Intracellular Accumulation (intracellular + accumulation)

Distribution by Scientific Domains
Distribution within Medical Sciences

Kinds of Intracellular Accumulation

  • increased intracellular accumulation


  • Selected Abstracts


    The role of taurine in diabetes and the development of diabetic complications

    DIABETES/METABOLISM: RESEARCH AND REVIEWS, Issue 5 2001
    Svend Hime Hansen
    Abstract The ubiquitously found ,-amino acid taurine has several physiological functions, e.g. in bile acid formation, as an osmolyte by cell volume regulation, in the heart, in the retina, in the formation of N -chlorotaurine by reaction with hypochlorous acid in leucocytes, and possibly for intracellular scavenging of carbonyl groups. Some animals, such as the cat and the C57BL/6 mouse, have disturbances in taurine homeostasis. The C57BL/6 mouse strain is widely used in diabetic and atherosclerotic animal models. In diabetes, the high extracellular levels of glucose disturb the cellular osmoregulation and sorbitol is formed intracellularly due to the intracellular polyol pathway, which is suspected to be one of the key processes in the development of diabetic late complications and associated cellular dysfunctions. Intracellular accumulation of sorbitol is most likely to cause depletion of other intracellular compounds including osmolytes such as myo -inositol and taurine. When considering the clinical complications in diabetes, several links can be established between altered taurine metabolism and the development of cellular dysfunctions in diabetes which cause the clinical complications observed in diabetes, e.g. retinopathy, neuropathy, nephropathy, cardiomyopathy, platelet aggregation, endothelial dysfunction and atherosclerosis. Possible therapeutic perspectives could be a supplementation with taurine and other osmolytes and low-molecular compounds, perhaps in a combinational therapy with aldose reductase inhibitors. Copyright 2001 John Wiley & Sons, Ltd. [source]


    Fermentative production of l -glycerol 3-phosphate utilizing a Saccharomyces cerevisiae strain with an engineered glycerol biosynthetic pathway,

    BIOTECHNOLOGY & BIOENGINEERING, Issue 3 2008
    A. Popp
    Abstract Interest in l -glycerol 3-phosphate (l -G3P) production via microbial fermentation is due to the compound's potential to replace the unstable substrate dihydroxyacetone phosphate (DHAP) in one-pot enzymatic carbohydrate syntheses. A Saccharomyces cerevisiae strain with deletions in both genes encoding specific l -G3Pases (GPP1 and GPP2) and multicopy overexpression of l -glycerol 3-phosphate dehydrogenase (GPD1) was studied via small-scale (100 mL) batch fermentations under quasi-anaerobic conditions. Intracellular accumulation of l -G3P reached extremely high levels (roughly 200 mM) but thereafter declined. Extracellular l -G3P was also detected and its concentration continuously increased throughout the fermentation, such that most of the total l -G3P was found outside the cells as fermentation concluded. Moreover, in spite of the complete elimination of specific l -G3Pase activity, the strain showed considerable glycerol formation suggesting unspecific dephosphorylation as a mechanism to relieve cells of intracellular l -G3P accumulation. Up-scaling the process employed fed-batch fermentation with repeated glucose feeding, plus an aerobic growth phase followed by an anaerobic product accumulation phase. This produced a final product titer of about 325 mg total l -G3P per liter of fermentation broth. Biotechnol. Bioeng. 2008;100: 497,505. 2008 Wiley Periodicals, Inc. [source]


    The sulphonylurea glibenclamide inhibits multidrug resistance protein (MRP1) activity in human lung cancer cells

    BRITISH JOURNAL OF PHARMACOLOGY, Issue 3 2001
    La Payen
    Glibenclamide, a sulphonylurea widely used for the treatment of non-insulin-dependent diabetes mellitus, has been shown to inhibit the activities of various ATP-binding cassette (ABC) transporters. In the present study, its effects towards multidrug resistance protein 1 (MRP1), an ABC efflux pump conferring multidrug resistance and handling organic anions, were investigated. Intracellular accumulation of calcein, an anionic dye substrate for MRP1, was strongly increased by glibenclamide in a dose-dependent manner in MRP1-overexpressing lung tumour GLC4/Sb30 cells through inhibition of MRP1-related calcein efflux. By contrast, glibenclamide did not alter calcein levels in parental control GLC4 cells. Another sulphonylurea, tolbutamide, was however without effect on calcein accumulation in both GLC4/Sb30 and GLC4 cells. Glibenclamide used at 12.5 ,M was, moreover, found to strongly enhance the sensitivity of GLC4/Sb30 cells towards vincristine, an anticancer drug handled by MRP1. Efflux of carboxy-2,,7,-dichlorofluorescein, an anionic dye handled by the ABC transporter MRP2 sharing numerous substrates with MRP1 and expressed at high levels in liver, was also strongly inhibited by glibenclamide in isolated rat hepatocytes. In summary, glibenclamide reversed MRP1-mediated drug resistance likely through inhibiting MRP1 activity and blocked organic anion efflux from MRP2-expressing hepatocytes. Such effects associated with the known inhibitory properties of glibenclamide towards various others ABC proteins suggest that this sulphonylurea is a general inhibitor of ABC transporters. British Journal of Pharmacology (2001) 132, 778,784; doi:10.1038/sj.bjp.0703863 [source]


    Induction of apoptosis by A3 adenosine receptor agonist N6 -(3-iodobenzyl)-adenosine-5,- N -methylcarboxamide in human leukaemia cells: a possible involvement of intracellular mechanism

    ACTA PHYSIOLOGICA, Issue 2 2010
    P. Mlejnek
    Abstract Aim:, The sensitivity of cancer cells which exhibit multi-drug resistance phenotype to A3 adenosine receptor (A3AR) agonist N6 -(3-iodobenzyl)-adenosine-5,- N -methylcarboxamide (IB-MECA) was studied. Methods:, To establish direct relationship between P-glycoprotein (P-gp, ABCB1 and MDR1) expression and IB-MECA induced cell death, a straightforward method for precise estimation of intracellular level of this A3AR agonist was developed. Results:, We subjected three human leukaemia cell lines HL-60, K562 and K562/HHT to treatment with micromolar concentrations of IB-MECA. Although all cell lines used expressed A3AR, there was a large difference in their sensitivity to IB-MECA. While HL-60 and K562 cells were almost equally sensitive, the K562/HHT cells, which exhibit a multi-drug resistance phenotype because of overexpression of P-gp, were significantly more resistant. We found that the intracellular level of IB-MECA in K562/HHT cells was approx. 10 times lower than those in HL-60 or K562 cells. Inhibitors of P-gp, including cyclosporine A (CsA) and verapamil (Vpa), increased the intracellular level of IB-MECA and reversed the resistance of K562/HHT cells to this drug. Accordingly, shRNA-mediated down-regulation of P-gp significantly increased the intracellular level of IB-MECA in K562/HHT cells which simultaneously exhibited reduced resistance to this A3AR agonist. In addition, an in vitro enzyme-based assay provided evidence that IB-MECA might serve as a substrate for P-gp. Conclusion:, Our results suggest that P-gp overexpression prevents cells from IB-MECA induced apoptosis despite the A3AR expression. Pro-apoptotic effect of IB-MECA seemed to strongly depend on its intracellular accumulation rather than on its interaction with A3AR. [source]


    Dynamics of P2X7 receptor pore dilation: Pharmacological and functional consequences

    DRUG DEVELOPMENT RESEARCH, Issue 2-3 2001
    I.P. Chessell
    Abstract The biophysical and functional properties of the human P2X7 receptor, expressed recombinantly in HEK-293 cells or natively in THP-1 pro-monocytic cells, were investigated in the context of pore dilation and externalisation of mature interleukin 1, (IL1,). In HEK-293 cells, the agonist 2,- and 3,-O-(4-benzoylbenzoyl)-ATP (BzATP) caused concentration-dependent inward currents (EC50 59 ,M) and with prolonged application this agonist caused a gradual increase in inward current culminating in a plateau. This increase in current was associated with pore dilation, determined by intracellular accumulation of YO-PRO-1. BzATP displayed increased potency at the pore-dilated form of the P2X7 receptor (EC50 17 ,M), and positive correlations between apparent receptor density and speed of pore dilation were observed. A monoclonal antibody selectively blocked current mediated by the nave receptor, while currents through pore-dilated receptors were not significantly affected, which together suggest a conformational change at the level of the receptor during the dilation event. The release of mature IL1, from THP-1 cells was independent of P2X7 -mediated cell lysis, as determined by study of lactate dehydrogenase release. Moreover, using conditions designed to minimise pore dilation (using buffers containing 2 mM Ca2+ and 1 mM Mg2+), BzATP caused significant release of IL1,, but without concomitant YO-PRO-1 accumulation, indicating pore dilation is not required for IL1, release. In addition, short (4-min) incubation of THP-1 cells with BzATP (terminated by enzymatic degradation of BzATP using apyrase) resulted in significant quantities of IL1, release some 60 min later, suggesting commitment of cells to release IL1, can be triggered with only brief receptor ligation. These findings suggest that receptor expression and ligation time are critical factors for selecting multiple functional states of P2X7. Drug Dev. Res. 53:60,65, 2001. 2001 Wiley-Liss, Inc. [source]


    Enhancement of the NAD(P)(H) Pool in Saccharomyces cerevisiae

    ENGINEERING IN LIFE SCIENCES (ELECTRONIC), Issue 4 2008
    A. Knepper
    Abstract Asymmetric biosyntheses allow for an efficient production of chiral building blocks. The application of whole cells as biocatalysts for asymmetric syntheses is advantageous because they already contain the essential coenzymes NAD(H) or NADP(H), which additionally can be regenerated in the cells. Unfortunately, reduced catalytic activity compared to the oxidoreductase activity is observed in many cases during whole-cell biotransformation. This may be caused by low intracellular coenzyme pool sizes and/or a decline in intracellular coenzyme concentrations. To enhance the intracellular coenzyme pool sizes, the effects of the precursor metabolites adenine and nicotinic acid on the intracellular accumulation of NAD(H) and NADP(H) were studied in Saccharomyces cerevisiae. Based on the results of simple batch experiments with different precursor additions, fed-batch processes for the production of yeast cells with enhanced NAD(H) or enhanced NADP(H) pool sizes were developed. Supplementation of the feed medium with 95,mM adenine and 9.5,mM nicotinic acid resulted in an increase of the intracellular NAD(H) concentration by a factor of 10 at the end of the fed-batch process compared to the reference process. The final NAD(H) concentration remains unchanged if the feed medium was solely supplemented with 95,mM adenine, but intracellular NADP(H) was increased by a factor of 4. The effects of NADP(H) pool sizes on the asymmetric reduction of ethyl-4-chloro acetoacetate (CAAE) to the corresponding (S)-4-chloro-3-hydroxybutanoate (S-CHBE) was evaluated with S.,cerevisiae,FasB,His6 as an example. An intracellular threshold concentration above 0.07,mM NADP(H) was sufficient to increase the biocatalytic S-CHBE productivity by 25,% compared to lower intracellular NADP(H) concentrations. [source]


    Genetically engineered Pseudomonas: a factory of new bioplastics with broad applications

    ENVIRONMENTAL MICROBIOLOGY, Issue 10 2001
    Elas R. Olivera
    Summary New bioplastics containing aromatic or mixtures of aliphatic and aromatic monomers have been obtained using genetically engineered strains of Pseudomonas putida. The mutation (,) or deletion (,) of some of the genes involved in the ,-oxidation pathway (fadA,, fadB,,fadA or ,fad,BA mutants) elicits a strong intracellular accumulation of unusual homo- or co-polymers that dramatically alter the morphology of these bacteria, as more than 90% of the cytoplasm is occupied by these macromolecules. The introduction of a blockade in the ,-oxidation pathway, or in other related catabolic routes, has allowed the synthesis of polymers other than those accumulated in the wild type (with regard to both monomer size and relative percentage), the accumulation of certain intermediates that are rapidly catabolized in the wild type and the accumulation in the culture broths of end catabolites that, as in the case of phenylacetic acid, phenylbutyric acid, trans -cinnamic acid or their derivatives, have important medical or pharmaceutical applications (antitumoral, analgesic, radiopotentiators, chemopreventive or antihelmintic). Furthermore, using one of these polyesters (poly 3-hydroxy-6-phenylhexanoate), we obtained polymeric microspheres that could be used as drug vehicles. [source]


    Examination of intravenous and intra-CSF protein delivery for treatment of neurological disease

    EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 6 2009
    Kim M. Hemsley
    Abstract Mucopolysaccharidosis type IIIA is a neurodegenerative lysosomal storage disorder characterized by progressive loss of learned skills, sleep disturbance and behavioural problems. Absent or greatly reduced activity of sulphamidase, a lysosomal protein, results in intracellular accumulation of heparan sulphate. Subsequent neuroinflammation and neurodegeneration typify this and many other lysosomal storage disorders. We propose that intra-cerebrospinal fluid protein delivery represents a potential therapeutic avenue for treatment of this and other neurodegenerative conditions; however, technical restraints restrict examination of its use prior to adulthood in mice. We have used a naturally-occurring Mucopolysaccharidosis type IIIA mouse model to determine the effectiveness of combining intravenous protein replacement (1 mg/kg) from birth to 6 weeks of age with intra-cerebrospinal fluid sulphamidase delivery (100 ,g, fortnightly from 6 weeks) on behaviour, the level of heparan sulphate-oligosaccharide storage and other neuropathology. Mice receiving combination treatment exhibited similar clinical improvement and reduction in heparan sulphate storage to those only receiving intra-cerebrospinal fluid enzyme. Reductions in micro- and astrogliosis and delayed development of ubiquitin-positive lesions were seen in both groups. A third group of intravenous-only treated mice did not exhibit clinical or neuropathological improvements. Intra-cerebrospinal fluid injection of sulphamidase effectively, but dose-dependently, treats neurological pathology in Mucopolysaccharidosis type IIIA, even when treatment begins in mice with established disease. [source]


    Microglial glutamate uptake is coupled to glutathione synthesis and glutamate release

    EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 4 2006
    Mikael Persson
    Abstract The physiological function of microglial glutamate uptake has been debated as it is about 10% of that measured for astrocytes. This study addresses how glutamate, taken up from the extracellular space, is utilized by microglia. It was found that purified rat microglia incubated for 60 min with 3H-glutamate had an increased intracellular accumulation of 3H-glutamate after 12 h incubation with tumour necrosis factor alpha (TNF-,) but not after incubation with lipopolysaccharide (LPS). Furthermore, LPS- but not TNF-,-treated cells showed an increased efflux of 3H-labelled compounds, presumably glutamate through the XC, system and treatment with LPS or TNF-, increased the microglial glutathione concentrations and led to an increased incorporation of 3H-glutamate into glutathione. Depending on the stimuli, 3,6% of the total labelled contents were found in the form of glutathione and 25,35% in the form of glutamate. These results show that microglial glutamate uptake is directly coupled to glutathione synthesis and release of glutamate and/or glutamate metabolites. Additionally, the increased glutathione contents after LPS or TNF-, treatment were able to reduce microglial cell death after H2O2 challenge, showing a potential (self)-protective function for microglial glutamate transporter expression and glutathione synthesis. [source]


    Glycation of low-density lipoprotein results in the time-dependent accumulation of cholesteryl esters and apolipoprotein B-100 protein in primary human monocyte-derived macrophages

    FEBS JOURNAL, Issue 6 2007
    Bronwyn E. Brown
    Nonenzymatic covalent binding (glycation) of reactive aldehydes (from glucose or metabolic processes) to low-density lipoproteins has been previously shown to result in lipid accumulation in a murine macrophage cell line. The formation of such lipid-laden cells is a hallmark of atherosclerosis. In this study, we characterize lipid accumulation in primary human monocyte-derived macrophages, which are cells of immediate relevance to human atherosclerosis, on exposure to low-density lipoprotein glycated using methylglyoxal or glycolaldehyde. The time course of cellular uptake of low-density lipoprotein-derived lipids and protein has been characterized, together with the subsequent turnover of the modified apolipoprotein B-100 (apoB) protein. Cholesterol and cholesteryl ester accumulation occurs within 24 h of exposure to glycated low-density lipoprotein, and increases in a time-dependent manner. Higher cellular cholesteryl ester levels were detected with glycolaldehyde-modified low-density lipoprotein than with methylglyoxal-modified low-density lipoprotein. Uptake was significantly decreased by fucoidin (an inhibitor of scavenger receptor SR-A) and a mAb to CD36. Human monocyte-derived macrophages endocytosed and degraded significantly more 125I-labeled apoB from glycolaldehyde-modified than from methylglyoxal-modified, or control, low-density lipoprotein. Differences in the endocytic and degradation rates resulted in net intracellular accumulation of modified apoB from glycolaldehyde-modified low-density lipoprotein. Accumulation of lipid therefore parallels increased endocytosis and, to a lesser extent, degradation of apoB in human macrophages exposed to glycolaldehyde-modified low-density lipoprotein. This accumulation of cholesteryl esters and modified protein from glycated low-density lipoprotein may contribute to cellular dysfunction and the increased atherosclerosis observed in people with diabetes, and other pathologies linked to exposure to reactive carbonyls. [source]


    Formation of cholesterol-enriched structures by aberrant intracellular accumulation of ATP-binding cassette transporter A1

    GENES TO CELLS, Issue 8 2008
    Arowu R. Tanaka
    ATP-binding cassette transporter A1 (ABCA1) is a key transporter associated with excess cellular lipid efflux. Here, we report that in HEK293 cells ABCA1 functions in intracellular compartments along the endocytic pathway. Inhibition of ABCA1-GFP degradation with proteasome inhibitors induced the internalization of ABCA1 and the formation of intracellular round-shaped structures, designated "A1 bodies". Importantly, cholesterol was selectively accumulated in A1 bodies, and this depended on the cholesterol efflux activity of ABCA1. Treatment with either lactacystin or acetylated LDL, which reduces proteasome activity, resulted in internalization of ABCA1 in mouse peritoneal macrophages. By performing array analysis on macrophages treated with these reagents, we identified Rab4 as a key protein involved in the internalization and aberrant accumulation of ABCA1 in HEK cells. Treatment of the cells with proteasome inhibitors inhibited the degradation of Rab4, and Rab4 over-expression induced the formation of small A1 bodies. Furthermore, A1 bodies formation was substantially inhibited by silencing of the endogenous Rab4 gene. Taken together, our findings suggest that the endocytic ABCA1 possesses cholesterol efflux activity, and thus the cellular control of post-endocytic sorting, retention or recycling of functional ABCA1 in the endocytic vesicles, which is in part regulated by Rab4, is important for cholesterol metabolism in living cells. [source]


    Novel mechanism of antibodies to hepatitis B virus in blocking viral particle release from cells,

    HEPATOLOGY, Issue 3 2010
    Avidan U. Neumann
    Antibodies are thought to exert antiviral activities by blocking viral entry into cells and/or accelerating viral clearance from circulation. In particular, antibodies to hepatitis B virus (HBV) surface antigen (HBsAg) confer protection, by binding circulating virus. Here, we used mathematical modeling to gain information about viral dynamics during and after single or multiple infusions of a combination of two human monoclonal anti-HBs (HepeX-B) antibodies in patients with chronic hepatitis B. The antibody HBV-17 recognizes a conformational epitope, whereas antibody HBV-19 recognizes a linear epitope on the HBsAg. The kinetic profiles of the decline of serum HBV DNA and HBsAg revealed partial blocking of virion release from infected cells as a new antiviral mechanism, in addition to acceleration of HBV clearance from the circulation. We then replicated this approach in vitro, using cells secreting HBsAg, and compared the prediction of the mathematical modeling obtained from the in vivo kinetics. In vitro, HepeX-B treatment of HBsAg-producing cells showed cellular uptake of antibodies, resulting in intracellular accumulation of viral particles. Blocking of HBsAg secretion also continued after HepeX-B was removed from the cell culture supernatants. Conclusion: These results identify a novel antiviral mechanism of antibodies to HBsAg (anti-HBs) involving prolonged blocking of the HBV and HBsAg subviral particles release from infected cells. This may have implications in designing new therapies for patients with chronic HBV infection and may also be relevant in other viral infections. (HEPATOLOGY 2010;) [source]


    The dual EGFR/HER-2 tyrosine kinase inhibitor lapatinib sensitizes colon and gastric cancer cells to the irinotecan active metabolite SN-38

    INTERNATIONAL JOURNAL OF CANCER, Issue 12 2009
    Melissa J. LaBonte
    Abstract Members of the human epidermal receptor (HER) family are frequently associated with aggressive disease and poor prognosis in multiple malignancies. Lapatinib is a dual tyrosine kinase inhibitor targeting the epidermal growth factor receptor (EGFR) and HER-2. This study evaluated the therapeutic potential of lapatinib, alone and in combination with SN-38, the active metabolite of irinotecan (CPT-11), in colon and gastric cancer cell lines. Concentration-dependent antiproliferative effects of both lapatinib and SN-38 were observed in all colon and gastric cancer cell lines tested but varied significantly between individual cell lines (lapatinib range 0.08,11.7 ,M; SN-38 range 3.6,256 nM). Lapatinib potently inhibited the growth of a HER-2 overexpressing gastric cancer cell line and demonstrated moderate activity in gastric and colon cancer cells with detectable HER-2 expression. The combination of lapatinib and SN-38 interacted synergistically to inhibit cell proliferation in all colon and gastric cancer cell lines tested. Cotreatment with lapatinib and SN-38 also resulted in enhanced cell cycle arrest and the induction of apoptosis with subsequent cellular pharmacokinetic analysis demonstrating that lapatinib promoted the increased intracellular accumulation and retention of SN-38 when compared to SN-38 treatment alone. Finally, the combination of lapatinib and CPT-11 demonstrated synergistic antitumor efficacy in the LoVo colon cancer mouse xenograft model with no apparent increase in toxicity compared to CPT-11 monotherapy. These results provide compelling preclinical rationale indicating lapatinib to be a potentially efficacious chemotherapeutic combination partner for irinotecan in the treatment of gastrointestinal carcinomas. 2009 UICC [source]


    Novel inhibitors targeted to methionine aminopeptidase 2 (MetAP2) strongly inhibit the growth of cancers in xenografted nude model

    INTERNATIONAL JOURNAL OF CANCER, Issue 1 2005
    Eunyoung Chun
    Abstract Inhibition of angiogenesis is emerging as a promising strategy for the treatment of cancer. In our study reported here, the effects of 4 highly potent methionine aminopeptidase 2 (MetAP2) inhibitors, IDR-803, IDR-804, IDR-805 and CKD-732 (designed by structure-based molecular modeling), on angiogenesis and tumor growth were assessed. Concentrations of these inhibitors as low as 2.5 nM were able to inhibit the growth of human umbilical vein endothelial cells (HUVEC) by as much as 50%, arresting growth in the G1 stage of mitosis. An intracellular accumulation of p21WAF1/Cip1 protein was also observed. Furthermore, at higher concentrations (25 nM) of these 4 MetAP2 inhibitors, a significant induction of apoptosis was apparent in the same HUVEC cultures. As a result of these findings, the possible anticancer effects of these inhibitors were examined, utilizing the SNU-398 hepatoma cell line. Interestingly, pretreatment with these inhibitors led to an increased number of apoptotic cells of up to 60% or more, compared to untreated controls. Moreover, utilizing an in vivo xenografted murine model, these inhibitors suppressed the growth of engrafted tumor. In conclusion, these 4 inhibitory compounds potently exert an antiangiogenic effect to inhibit the growth of cancers in vivo and could potentially be useful for the treatment of a variety of cancers. 2004 Wiley-Liss, Inc. [source]


    ABCG2 overexpression in colon cancer cells resistant to SN38 and in irinotecan-treated metastases

    INTERNATIONAL JOURNAL OF CANCER, Issue 6 2004
    Laurent Candeil
    Abstract Overcoming drug resistance has become an important issue in cancer chemotherapy. Among all known mechanisms that confer resistance, active efflux of chemotherapeutic agents by proteins from the ATP-binding cassette family has been extensively reported. The aim of the present study was to determine the involvement of ABCG2 in resistance to SN38 (the active metabolite of irinotecan) in colorectal cancer. By progressive exposure to increasing concentrations of SN38, we isolated 2 resistant clones from the human colon carcinoma cell line HCT116. These clones were 6- and 53-fold more resistant to SN38 than the HCT116-derived sensitive clone. Topoisomerase I expression was unchanged in our resistant variants. The highest resistance level correlated with an ABCG2 amplification. This overexpression was associated with a marked decrease in the intracellular accumulation of SN38. The inhibition of ABCG2 function by Ko143 demonstrated that enhanced drug efflux from resistant cells was mediated by the activity of ABCG2 protein and confirmed that ABCG2 is directly involved in acquired resistance to SN38. Furthermore, we show, for the first time in clinical samples, that the ABCG2 mRNA content in hepatic metastases is higher after an irinotecan-based chemotherapy than in irinotecan-naive metastases. In conclusion, this study supports the potential involvement of ABCG2 in the development of irinotecan resistance in vivo. 2004 Wiley-Liss, Inc. [source]


    A Japanese case of Kindler syndrome

    INTERNATIONAL JOURNAL OF DERMATOLOGY, Issue 4 2000
    Yasushi Suga MD
    A 25-year-old Japanese woman presented with contracture of the fingers and toes, and difficulty in opening her mouth. Her grandparents are first cousins, but none of the other members of the family are affected. Bulla formation started at birth on areas of the skin that received pressure, and in infancy and early childhood the lesions were limited only to the acral areas. She also had bilateral, incomplete syndactylies involving all web spaces ( Fig. 1a). The formation of blisters ceased after the age of 15 years, but a generalized progressive poikiloderma then appeared with accompanying cutaneous atrophy of the skin of the neck, trunk, and extremities ( Fig. 1b). The patient experienced mild photosensitivity of the face and neck. At age 18 years, surgical removal of the webbing of all her fingers was performed. Oral examination showed atrophy of the buccal mucosa, and an inability to fully open the mouth. The patient also suffered from poor dentition and easily bleeding gums, but had no symptoms of esophageal dysfunction. Figure 1. Clinical manifestations of the patient with Kindler syndrome. (a) Dorsal surface of the patient's hands. Note the marked cutaneous atrophy with a severely wrinkled appearance on the dorsal surface of the hands, as well as the proximal fusion of the fingers. (b) Lower left leg of the patient. Atrophic thinning of the skin and poikiloderma with reticular pigmentation are evident Histology of separate biopsy specimens, taken from the poikilodermatous pretibial and trunk skin, showed classical features of poikiloderma, namely epidermal atrophy with flattening of the rete ridges, vacuolization of basal keratinocytes, pigmentary incontinence, and mild dermal perivascularization ( Fig. 2a). Interestingly, dyskeratotic cells ( Fig. 2b) and eosinophilic rounded bodies (colloid bodies) ( Fig. 2c) were frequently found at the basal keratinocyte layer and in the upper dermis, respectively. Pigment was also present in the upper epidermis. Figure 2. Hematoxylin and eosin staining of a biopsy specimen taken from pretibial skin. (a) Epidermal atrophy with flattening of the rete ridges. Note the dyskeratotic cells (arrowheads) and vacuolar degeneration of the basal layer in the epidermis. Bar = 50 ,m. (b) Higher magnification of dyskeratotic cells (arrowheads). Bar = 10 ,m. (c) Higher magnification of colloid bodies (arrowheads) in the superficial dermis. Bar = 10 ,m To rule out the possibility of a congenital epidermolysis bullosa, ultrastructural and immunofluorescence studies were performed. Ultrastructural studies demonstrated the reduplication of the basal lamina with branching structures within the upper dermis and cleavage between the lamina densa and the cell membrane of the keratinocytes ( Fig. 3a). The numbers of associated anchoring fibrils did not seem to be reduced, and colloid bodies and dyskeratotic cells were detected. Immunofluorescence studies with the antibody against type VII collagen (LH 7 : 2) were subsequently carried out. The results showed extensive broad bands with intermittently discontinuous and reticular staining at the dermo-epidermal junction (DEJ) ( Fig. 3b), whereas a linear distribution is typically seen in healthy tissue (data not shown). Interestingly, direct immunofluorescence studies revealed intracellular accumulation of immunoglobulin G (IgG), IgM, IgA, and C3 in colloid bodies under the basement membrane ( Fig. 3c). Figure 3. Ultrastructural and immunohistochemical findings of the patient with Kindler syndrome. (a) Ultrastructural study of the dermo-epidermal junction. The branching structures of the lamina densa (arrowheads) were frequently seen. The asterisks show the cleavage in the lamina lucida. Bar = 1 ,m. (b) Immunohistochemical studies with the antibody to type VII collagen (LH 7 : 2). An extensive broad band with reticular patterns is evident. Bar = 50 ,m. E, epidermis; D, dermis. (c) Direct immunofluorescence study. Intracytoplasmic deposition of IgM in the basal keratinocytes is evident (arrowheads). Bar = 50 ,m. E, epidermis; D, dermis [source]


    Melatonin protects against taurolithocholic-induced oxidative stress in rat liver

    JOURNAL OF CELLULAR BIOCHEMISTRY, Issue 5 2010
    Lorena Fuentes-Broto
    Abstract Cholestasis, encountered in a variety of clinical disorders, is characterized by intracellular accumulation of toxic bile acids in the liver. Furthermore, oxidative stress plays an important role in the pathogenesis of bile acids. Taurolithocholic acid (TLC) was revealed in previous studies as the most pro-oxidative bile acid. Melatonin, a well-known antioxidant, is a safe and widely used therapeutic agent. Herein, we investigated the hepatoprotective role of melatonin on lipid and protein oxidation induced by TLC alone and in combination with FeCl3 and ascorbic acid in rat liver homogenates and hepatic membranes. The lipid peroxidation products, malondialdehyde and 4-hydroxyalkenals (MDA,+,4-HDA), and carbonyl levels were quantified as indices of oxidative damage to hepatic lipids and proteins, respectively. In the current study, the rise in MDA,+,4-HDA levels induced by TLC was inhibited by melatonin in a concentration-dependent manner in both liver homogenates and in hepatic membranes. Melatonin also had protective effects against structural damage to proteins induced by TLC in membranes. These results suggest that the indoleamine melatonin may potentially act as a protective agent in the therapy of those diseases that involve bile acid toxicity. J. Cell. Biochem. 110: 1219,1225, 2010. Published 2010 Wiley-Liss, Inc. [source]


    Hypocalcemia in a critically ill patient

    JOURNAL OF VETERINARY EMERGENCY AND CRITICAL CARE, Issue 2 2005
    Tamara B. Wills DVM
    Abstract Objective: To present a case of clinical hypocalcemia in a critically ill septic dog. Case summary: A 12-year old, female spayed English sheepdog presented in septic shock 5 days following hemilaminectomy surgery. Streptococcus canis was cultured from the incision site. Seven days after surgery, muscle tremors were noted and a subsequent low serum ionized calcium level was measured and treated. Intensive monitoring, fluid therapy, and antibiotic treatment were continued because of the sepsis and hypocalcemia, but the dog was euthanized 2 weeks after surgery. New or unique information provided: Low serum ionized calcium levels are a common finding in critically ill human patients, especially in cases of sepsis, pancreatitis, and rhabdomyolysis. In veterinary patients, sepsis or streptococcal infections are not commonly thought of as a contributing factor for hypocalcemia. Potential mechanisms of low serum ionized calcium levels in critically ill patients include intracellular accumulation of calcium ions, altered sensitivity and function of the parathyroid gland, alterations in Vitamin D levels or activity, renal loss of calcium, and severe hypomagnesemia. Pro-inflammatory cytokines and calcitonin have also been proposed to contribute to low ionized calcium in the critically ill. Many veterinarians rely on total calcium levels instead of serum ionized calcium levels to assess critical patients and may be missing the development of hypocalcemia. Serum ionized calcium levels are recommended over total calcium levels to evaluate critically ill veterinary patients. [source]


    Effect of the proton motive force inhibitor carbonyl cyanide- m -chlorophenylhydrazone (CCCP) on Pseudomonas aeruginosa biofilm development

    LETTERS IN APPLIED MICROBIOLOGY, Issue 4 2008
    A. Ikonomidis
    Abstract Aims:, Proton motive force (PMF) inhibition enhances the intracellular accumulation of autoinducers possibly interfering with biofilm formation. We evaluated the effect of the PMF inhibitor carbonyl cyanide- m -chlorophenylhydrazone (CCCP) on Pseudomonas aeruginosa biofilm development. Methods and Results:, Four epidemiologically unrelated P. aeruginosa isolates were studied. A MexAB-oprM overproducing strain was used as control. Expression of gene mexB was examined and biofilm formation after incubation with 0, 125 and 25 ,mol l,1 of CCCP was investigated. Mean values of optical density were analysed with one-way analysis of variance and t -test. Two isolates subexpressed mexB gene and only 25 ,mol l,1 of CCCP affected biofilm formation. Biofilms of the other two isolates and control strain PA140 exhibited significantly lower absorbance (P ranging from <001 to <005) with either 125 or 25 ,mol l,1 of CCCP. Conclusions:, The PMF inhibitor CCCP effect was correlated with the expression of MexAB-OprM efflux system and found to compromise biofilm formation in P. aeruginosa. Significance and Impact of the Study:, These data suggest that inhibition of PMF-dependent trasporters might decrease biofilm formation in P. aeruginosa. [source]


    Independent estimation of T*2 for water and fat for improved accuracy of fat quantification

    MAGNETIC RESONANCE IN MEDICINE, Issue 4 2010
    Venkata V. Chebrolu
    Abstract Noninvasive biomarkers of intracellular accumulation of fat within the liver (hepatic steatosis) are urgently needed for detection and quantitative grading of nonalcoholic fatty liver disease, the most common cause of chronic liver disease in the United States. Accurate quantification of fat with MRI is challenging due the presence of several confounding factors, including T*2 decay. The specific purpose of this work is to quantify the impact of T*2 decay and develop a multiexponential T*2 correction method for improved accuracy of fat quantification, relaxing assumptions made by previous T*2 correction methods. A modified Gauss-Newton algorithm is used to estimate the T*2 for water and fat independently. Improved quantification of fat is demonstrated, with independent estimation of T*2 for water and fat using phantom experiments. The tradeoffs in algorithm stability and accuracy between multiexponential and single exponential techniques are discussed. Magn Reson Med 63:849,857, 2010. 2010 Wiley-Liss, Inc. [source]


    Xylitol inhibition of anaerobic acid production by Streptococcus mutans at various pH levels

    MOLECULAR ORAL MICROBIOLOGY, Issue 4 2003
    H. Miyasawa
    Xylitol inhibits the glycolysis and growth of Streptococcus mutans. We studied the inhibitory effect of xylitol on the acid production of S. mutans at several pH levels under the strictly anaerobic conditions found in the deep layer of dental plaque. Xylitol inhibited the rate of acid production from glucose and changed the profile of acidic end products to formate,acetate dominance, with a decrease in the intracellular level of fructose 1,6-bisphosphate and an intracellular accumulation of xylitol 5-phosphate (X5P). These results were notable at pH 5.5,7.0, but were not evident at pH 5.0. Since the activity of phosphoenolpyruvate phosphotransferase for xylitol was greater at higher pH, it is suggested that xylitol could be incorporated more efficiently at higher pH and that the resultant accumulation of X5P could inhibit the glycolysis of S. mutans more effectively. [source]


    Neuroprotective effects of Triticum aestivum L. against ,-Amyloid-induced cell death and memory impairments

    PHYTOTHERAPY RESEARCH, Issue 1 2010
    Jung-Hee Jang
    Abstract ,-Amyloid (A,) is a key component of senile plaques, neuropathological hallmarks of Alzheimer's disease (AD) and has been reported to induce cell death via oxidative stress. This study investigated the protective effects of Triticum aestivum L. (TAL) on A,-induced apoptosis in SH-SY5Y cells and cognitive dysfunctions in Sprague-Dawley (SD) rats. Cells treated with A, exhibited decreased viability and apoptotic features, such as DNA fragmentation, alterations in mitochondria and an increased Bax/Bcl-2 ratio, which were attenuated by TAL extract (TALE) pretreatment. To elucidate the neuroprotective mechanisms of TALE, the study examined A,-induced oxidative stress and cellular defense. TALE pretreatment suppressed A,-increased intracellular accumulation of reactive oxygen species (ROS) via up-regulation of glutathione, an essential endogenous antioxidant. To further verify the effect of TALE on memory impairments, A, or scopolamine was injected in SD rats and a water maze task conducted as a spatial memory test. A, or scopolamine treatment increased the time taken to find the platform during training trials, which was decreased by TALE pretreatment. Furthermore, one of the active components of TALE, total dietary fiber also effectively inhibited A,-induced cytotoxicity and scopolamine-caused memory deficits. These results suggest that TALE may have preventive and/or therapeutic potential in the management of AD. Copyright 2009 John Wiley & Sons, Ltd. [source]


    Lung cyst: An unusual manifestation of Niemann,Pick disease

    RESPIROLOGY, Issue 1 2009
    Bruno G. BALDI
    Abstract: Niemann,Pick disease is a rare inherited autosomal recessive disorder, currently classified into six subtypes and characterized by the intracellular accumulation of sphingomyelin in the liver, spleen, lungs, bone marrow or brain. The main pulmonary abnormalities described in high-resolution computed tomography (HRCT) of the chest consist of thickening of the interlobular septa and ground-glass opacities. This case report describes a patient with subtype B Niemann,Pick disease characterized by cysts and ground-glass opacities that were detected on HRCT of the chest. [source]


    Reduction of GAG storage in MPS II mouse model following implantation of encapsulated recombinant myoblasts

    THE JOURNAL OF GENE MEDICINE, Issue 11 2005
    Adelaide Friso
    Abstract Background Hunter syndrome, mucopolysaccharidosis type II (MPS II), is a X-linked inherited disorder caused by the deficiency of the enzyme iduronate-2-sulfatase (IDS), involved in the lysosomal catabolism of the glycosaminoglycans (GAG) dermatan and heparan sulfate. Such a deficiency leads to the intracellular accumulation of undegraded GAG and eventually to a progressive severe clinical pattern. Many attempts have been made in the last two to three decades to identify possible therapeutic strategies for the disorder, including gene therapy and somatic cell therapy. Methods In this study we evaluated the intraperitoneal implantation of allogeneic myoblasts over-expressing IDS, enclosed in alginate microcapsules, in the MPS II mouse model. Animals were monitored for 8 weeks post-implantation, during which plasma and tissue IDS levels, as well as tissue and urinary GAG contents, were measured. Results and conclusions Induced enzyme activity occurred both in the plasma and in the different tissues analyzed. A significant decrease in urinary undegraded GAG between the fourth and the sixth week of treatment was observed. Moreover, a biochemical reduction of GAG deposits was measured 8 weeks after treatment in the liver and kidney, on average 30 and 38%, respectively, while in the spleen GAG levels were almost normalized. Finally, the therapeutic effect was confirmed by histolochemical examination of the same tissues. Such effects were obtained following implantation of about 1.5 106 recombinant cells/animal. Taken together, these results represent a clear evidence of the therapeutic efficacy of this strategy in the MPS II mouse model, and encourage further evaluation of this approach for potential treatment of human beings. Copyright 2005 John Wiley & Sons, Ltd. [source]


    Alsin/Rac1 signaling controls survival and growth of spinal motoneurons

    ANNALS OF NEUROLOGY, Issue 1 2006
    Arnaud Jacquier MSc
    Objective Recessive mutations in alsin, a guanine-nucleotide exchange factor for the GTPases Rab5 and Rac1, cause juvenile amyotrophic lateral sclerosis (ALS2) and related motoneuron disorders. Alsin function in motoneurons remained unclear because alsin knock-out mice do not develop overt signs of motoneuron degeneration. Methods To generate an alsin loss-of-function model in an ALS-relevant cell type, we developed a new small interfering RNA electroporation technique that allows efficient knock down of alsin in embryonic rat spinal motoneurons. Results After small interfering RNA,mediated alsin knockdown, cultured motoneurons displayed a reduced apparent size of EEA1-labeled early endosomes and an increased intracellular accumulation of transferrin and L1CAM. Alsin knockdown induced cell death in 32 to 48% of motoneurons and significantly inhibited axon growth in the surviving neurons. Both cellular phenotypes were mimicked by expression of a dominant-negative Rac1 mutant and were completely blocked by expression of a constitutively active Rac1 mutant. Expression of dominant-negative or constitutively active forms of Rab5 had no such effects. Interpretation Our data demonstrate that alsin controls the growth and survival of motoneurons in a Rac1-dependant manner. The strategy reported here illustrates how small interfering RNA electroporation can be used to generate cellular models of neurodegenerative disease involving a loss-of-function mechanism. Ann Neurol 2006;60:105,117 [source]


    The accumulation of intracellular ITEGE and DIPEN neoepitopes in bovine articular chondrocytes is mediated by CD44 internalization of hyaluronan

    ARTHRITIS & RHEUMATISM, Issue 2 2006
    Jennifer J. Embry Flory
    Objective A dramatic loss of aggrecan proteoglycan from cartilage is associated with osteoarthritis. The fate of residual G1 domains of aggrecan is unknown, but inefficient turnover of these domains may impede subsequent repair and retention of newly synthesized aggrecan. Thus, the objective of this study was to determine whether ITEGE- and DIPEN-containing G1 domains, generated in situ, are internalized by articular chondrocytes, and whether these events are dependent on hyaluronan (HA) and its receptor, CD44. Methods ITEGE and DIPEN neoepitopes were detected by immunofluorescence staining of bovine articular cartilage chondrocytes treated with or without interleukin-1, (IL-1,). Additionally, purified ITEGE- or DIPEN-containing G1 domains were aggregated with HA and then added to articular chondrocytes, articular chondrocytes transfected with CD44,67, or COS-7 cells transfected with or without full-length CD44. Internalized epitopes were distinguished by their resistance to extensive trypsinization of the cell surface. Results Both ITEGE and DIPEN were visualized within the extracellular cell-associated matrix of chondrocytes as well as within intracellular vesicles. Following trypsinization, the intracellular accumulation of both epitopes was clearly visible. IL-1 treatment increased extracellular as well as intracellular ITEGE epitope accumulation. Once internalized, the ITEGE neoepitope became localized within the nucleus and displayed little colocalization with HA, DIPEN, or other G1 domain epitopes. The internalization of both ITEGE and DIPEN G1 domains was dependent on the presence of HA and CD44. Conclusion One important mechanism for the elimination of residual G1 domains following extracellular degradation of aggrecan is CD44-mediated co-internalization with HA. [source]


    Effects of bosentan, an endothelin receptor antagonist, on bile salt export pump and multidrug resistance,associated protein 2

    BIOPHARMACEUTICS AND DRUG DISPOSITION, Issue 1 2007
    Yuji Mano
    Abstract The bile salt export pump (BSEP/Bsep/ABCB11) and multidrug resistance-associated protein 2 (MRP2/Mrp2/ABCC2) are involved in bile acid-dependent and -independent bile secretion, respectively. It has been reported that bosentan, an endothelin receptor antagonist, inhibits Bsep, which may lead to cholestatic liver injury due to the intracellular accumulation of bile salts, while increasing bile salt-independent bile flow. Thus, in this study, the effects of bosentan on BSEP/Bsep and MRP2/Mrp2 were evaluated using membrane vesicles derived from Spodoptera frugiperda (Sf) 9 cells, which express these transporters. The adenosine 5,-triphosphate (ATP)-dependent uptake of 3H-taurocholic acid into membrane vesicles for BSEP/Bsep was inhibited by bosentan, and its IC50 values were 76.8 and 101 M for BSEP and Bsep, respectively. In contrast, bosentan stimulated the MRP2/Mrp2-mediated ATP-dependent vesicular transport of 3H-estradiol 17,-glucuronide by shifting the sigmoidal dependence of transport rate on substrate concentration to a more hyperbolic one. Collectively, these results suggest that bosentan inhibits BSEP in humans with a similar potency to rats, and that increased bile salt-independent flow in rats by bosentan is at least partly attributable to the activation of Mrp2. Copyright 2006 John Wiley & Sons, Ltd. [source]


    Regulation of XBP-1 signaling during transient and stable recombinant protein production in CHO cells

    BIOTECHNOLOGY PROGRESS, Issue 2 2010
    Sebastian C. Y. Ku
    Abstract X-box binding protein 1 (XBP-1) is a key regulator of cellular unfolded protein response (UPR). The spliced isoform of XBP-1, XBP-1S, is a transcription activator, which is expressed only when UPR is induced. However, the impact of recombinant protein production on the regulation of XBP-1 signaling in CHO cells is not well understood. In this report, we cloned the Chinese hamster XBP-1 homolog to aid the investigation of the interplay between protein productivity, culture conditions, and endogenous XBP-1 signaling in CHO cells. Interestingly, expression of XBP-1S is detected in the non-producing and unstressed CHO-K1 cells. Transient expression of recombinant erythropoietin reveals a positive correlation between XBP-1 mRNA abundance and protein production level. However, such a correlation is not observed in batch cultivation of stable producing cell lines. The increased XBP-1 splicing is detected in late-phase cultures, suggesting that induction of XBP-1S may be a result of nutrient limitations or other environmental stresses rather than that of increased intracellular accumulation of recombinant proteins. Our data suggest that XBP-1 is a key determinant for the secretory capacity of CHO cells. Understanding its dynamic regulation hence provides a rational basis for cellular engineering strategies to improve recombinant protein secretion. 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2010 [source]


    Intracellular and plasma steady-state pharmacokinetics of raltegravir, darunavir, etravirine and ritonavir in heavily pre-treated HIV-infected patients

    BRITISH JOURNAL OF CLINICAL PHARMACOLOGY, Issue 5 2010
    Rob Ter Heine
    WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT , The combination of raltegravir, etravirine and ritonavir boosted darunavir is a potent antiretroviral regimen for patients who have been heavily pre-treated for HIV-infection. All these agents have to exert their action intracellularly. However, only little is known about the cellular pharmacology of these agents. WHAT THIS STUDY ADDS , We investigated the steady-state plasma and cellular pharmacokinetics of raltegravir, etravirine, darunavir and ritonavir and the observed distinct intracellular accumulation ratios indicated that these antiretroviral drugs have different affinity for the cellular compartment. AIM To study the steady-state plasma and intracellular pharmacokinetics of raltegravir, etravirine, darunavir and ritonavir in heavily pre-treated patients. METHODS Patients on a salvage regimen containing raltegravir, etravirine, darunavir and ritonavir were eligible for inclusion. During a 12 h dosing interval plasma and peripheral blood mononuclear cells were collected. Drug concentrations were measured using a validated LC-MS/MS assay and pharmacokinetic analysis was performed using non-linear mixed effect modelling. RESULTS Irregular absorption was observed with raltegravir and darunavir, which may be caused by enterohepatic cycling. Relative bioavailability of ritonavir was low, when compared with other ritonavir regimens. Raltegravir plasma pharmacokinetics showed wide interpatient variability, while intracellular raltegravir concentrations could not be detected (<0.001 mg l,1 in cell lysate). The intracellular to plasma ratios for etravirine, darunavir and ritonavir were 12.9, 1.32 and 7.72, respectively, and the relative standard error of these estimates were 16.3%, 12.3% and 13.0%. CONCLUSIONS The observed distinct intracellular accumulation indicated that these drugs have different affinity for the cellular compartment. The relatively high intracellular accumulation of etravirine may explain its efficacy and its previously described absence of PK,PD relationships in the therapeutic concentration range, when compared with other non-nucleoside reverse transcriptase inhibitors. Lastly, the intracellular concentrations of ritonavir seem sufficient for inhibition of viral replication in the cellular compartment in PI-naive patients, but not in patients with HIV harbouring PI resistance. [source]


    Cultured CD4T cells and primary human lymphocytes express hOATPs: intracellular accumulation of saquinavir and lopinavir

    BRITISH JOURNAL OF PHARMACOLOGY, Issue 6 2008
    O Janneh
    Background and purpose: Drug efflux tranporters (P-glycoprotein (P-gp), multidrug resistance-associated protein (MRP)) limit the cellular uptake of human immunodeficiency virus protease inhibitors but the contribution of influx transporters in cells that (over)express P-gp or MRP is less clear. Here, we studied the expression of one influx transporter system, human organic anion-transporting polypeptide (hOATP), in some T-cell lines (CEM, CEMVBL, CEME1000) and in peripheral blood mononuclear cells (PBMCs) and examined the effects of manipulation of influx/efflux transporters on the uptake of saquinavir and lopinavir. Experimental approach: The expression of hOATPs was studied by PCR. We used hOATP substrate or inhibitor (estrone-3-sulphate (E-3-S) or montelukast, respectively) and inhibitors of P-gp (XR9576) and MRP (MK571 and frusemide) to study functional interactions between influx and efflux transporters in the uptake of saquinavir and lopinavir. Lipophilicity of the drugs was measured by octanol/saline partition coefficient. Key results: CEM cells, their variants and PBMCs express various hOATP isoforms, with OATP3A1 detected in all of the cells. MK571, XR9576 and frusemide increased the uptake of saquinavir and lopinavir. E-3-S and montelukast reduced the uptake of saquinavir and lopinavir in some, but not all, of the cells. Pretreatment of the cells with MK571, XR9576 or frusemide, followed by E-3-S co-incubation reduced the cellular accumulation of saquinavir and lopinavir. Lopinavir is much more lipophilic than saquinavir. Conclusions and implications: Human OATPs, MRP, P-gp and lipophilicity determine the cellular uptake and retention of saquinavir and lopinavir. These data may have important implications for drug,drug interactions, drug safety and efficacy. British Journal of Pharmacology (2008) 155, 875,883; doi:10.1038/bjp.2008.320; published online 18 August 2008 [source]