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Membrane Function (membrane + function)
Selected AbstractsImpact of selected inborn errors of metabolism on prenatal and neonatal developmentIUBMB LIFE, Issue 6 2010Sabine Illsinger Abstract In general, data regarding maturational processes of different metabolic pathways in the very vulnerable fetal and neonatal period are rare. This review is to substantiate the impact of selected inborn errors of metabolism on this critical period of life and their clinical manifestation. Significant adaptation of mitochondrial/energy-, carbohydrate-, lysosomal-, and amino acid-metabolism occurs during early prenatal and neonatal development. In utero, metabolic environment has an impact on the development of the fetus as well as fetal organ maturation. Defects of distinct metabolic pathways could therefore already be of significant relevance in utero and for clinical manifestations in the early fetal and neonatal period. Disturbances of these pathways may influence intrauterine growth and health. Production of a toxic intrauterine milieu, energy-deficiency, modification of membrane function, or disturbance of the normal intrauterine expression of genes may be responsible for fetal compromise and developmental disorders. Three categories of metabolic disorders will be discussed: the "intoxication type" (classical galactosemia, ornithine transcarbamylase deficiency, and "maternal phenylketonuria"), the "storage type" (Morbus Niemann Pick type C), and the "energy deficient type" (including long-chain fatty acid oxidation disorders, pyruvate dehydrogenase deficiency, and respiratory chain defects). For these disorders, the pathophysiology of early manifestation, special aspects regarding the prenatal and neonatal period, and diagnostic as well as therapeutic options are presented. © 2010 IUBMB IUBMB Life, 62(6): 403,413, 2010 [source] Maintaining clearance in peritoneal dialysisNEPHROLOGY, Issue 6 2001David W Johnson SUMMARY: Numerous studies have now established that there is a strong association between small solute clearance and improved outcomes in peritoneal dialysis (PD) patients. Preservation of both renal and peritoneal clearances is therefore of paramount importance, although very few trials have satisfactorily addressed this critical issue. Observational studies have suggested that the groups most at risk of loss of residual renal function are women, non-whites, diabetic patients, patients with congestive cardiac failure, patients who experience frequent episodes of peritonitis and, possibly, patients treated with automated PD (APD). There have been no controlled trials of renoprotective therapies in PD patients, but reasonable strategies for preventing renal functional decline include avoidance of nephrotoxins and infection, maintenance of adequate blood pressure, abstinence from smoking and possibly administration of angiotensin-converting enzyme inhibitors and/or calcium channel blockers. In contrast, peritoneal small solute removal can be maximized by augmenting fill volume, increasing exchange frequency and using either long-dwell continuous ambulatory PD (CAPD) or short-dwell (APD) therapies to suit individual patients' transport characteristics. Tidal PD may additionally increase solute clearance, although studies have reported conflicting findings. Preservation of membrane function may be achieved by minimizing episodes of peritonitis and avoiding hypertonic glucose exchanges. Newer peritoneal dialysates, such as icodextrin, amino acids, bicarbonate-buffered solutions and aldehyde-poor fluids, are more biocompatible in experimental models of PD, but their long-term clinical safety and efficacy have not yet been established by clinical trials. Moreover, no trials have demonstrated an independent effect of peritoneal clearance on patient outcomes. Further studies determining the relative value of renal and peritoneal clearances are therefore urgently required in order to optimize dialytic adequacy for PD patients. [source] Influence of organotin compounds on phosphatidylserine membranesAPPLIED ORGANOMETALLIC CHEMISTRY, Issue 3 2004José A. Teruel Abstract Organotin compounds are widely distributed toxicants. They are membrane-active molecules with broad biological toxicity. We have studied the interaction of tributyltin and triphenyltin with phosphatidylserine model membranes using differential scanning calorimetry, infrared spectroscopy and X-ray diffraction techniques. Organotin compounds produced a broadening of the gel to the liquid-crystalline phase transition of the phospholipid and a shifting of the phase transition temperature to lower values. Infrared spectroscopy experiments showed that tributyltin exerted a fluidizing effect on the apolar part of the bilayer, and that both tributyl- and triphenyltin interact with the interfacial region of the bilayer, making the carbonyl groups less accessible to water. As seen by X-ray diffraction experiments, organotin compounds were unable to change the bilayer macroscopic organization of the phospholipid, but they were able to reduce the long-range order of the multibilayer system and to disorder the packing of the phospholipid molecules. The observed interaction between organotin compounds and phosphatidylserine membranes promotes physical perturbations that could affect membrane function and may mediate some of their toxic effects. Copyright © 2004 John Wiley & Sons, Ltd. [source] Nutritional manipulation and psychiatric conditions: focus on mood and cognitionACTA NEUROPSYCHIATRICA, Issue 1 2003W. J. Riedel In this paper, several experimental models of human depression and cognitive dysfunction, which are designed specifically to mimic the proposed mechanisms of action of many nutritional supplements, are illustrated. These mechanisms of interest are antioxidant effects, glucose utilization, neuronal membrane function and neurotransmitter effects, with particular reference to nutrient-based amino acid manipulations of neurotransmission, such as tryptophan depletion. It is concluded that the application of experimental human models of altered mood and cognitive function may illuminate substantially the quest for nutritional enhancement of human mood and cognitive function. [source] Effects of mild aerobic physical exercise on membrane fluidity of erythrocytes in essential hypertensionCLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 5-6 2003Kazushi Tsuda Summary 1.,The present study was undertaken to investigate the effects of aerobic physical exercise on membrane function in mild essential hypertension. 2.,Hypertensive patients were divided into an exercise group (n = 8) and a non-exercise (control) group (n = 8). Physical exercise within the intensity of the anaerobic threshold level was performed twice a week for 6 months. Membrane fluidity of erythrocytes was examined by means of electron paramagnetic resonance (EPR) and spin-labelling methods before and after the trial period in both groups. 3.,After physical exercise, blood pressure decreased significantly. 4.,Compared with the non-exercise group, in the exercise group both the order parameter (S) and the peak height ratio (ho/h -1) in the EPR spectra of erythrocytes were significantly reduced (S, 0.717 ± 0.004 vs 0.691 ± 0.008, respectively (n = 8), P < 0.05; ho/h -1, 5.38 ± 0.06 vs 4.89 ± 0.06, respectively (n = 8), P < 0.05). These findings indicated that exercise increased membrane fluidity and improved the membrane microviscosity of erythrocytes. 5.,There was no direct correlation between blood pressure reduction and the exercise-induced increase in membrane fluidity of erythrocytes. 6.,In the non-exercise (control) group, blood pressure and membrane fluidity were not changed after a 6 month follow-up period. 7., The results show that aerobic physical exercise increased erythrocyte membrane fluidity and improved the rigidity of cell membranes in hypertensive patients. The improvement of rheological properties of erythrocytes may explain, in part, the cellular mechanisms for the beneficial effects of physical exercise in hypertension. [source] Aplasia cutis congenita, congenital heart lesions, and frontonasal cysts in four successive generationsCLINICAL GENETICS, Issue 6 2007RG Rodrigues We report a family with four known generations of individuals in the maternal family tree with aplasia cutis congenita (ACC) of the scalp, congenital heart lesions, brachydactyly, and frontonasal cysts. This is the first reported finding of craniofacial, digital, and cardiac abnormalities associated with ACC, likely representing a new variant of the autosomal dominant hidrotic ectodermal dysplasia subtype. These rare disorders are characterized by common anomalies of at least two elements of the ectoderm and its appendages, namely the skin, teeth, hair, nails, and sweat glands. These patients also frequently have chronic dental problems with early loss of teeth, and recurrent lung, ear, and nose infections secondary to a defect in mucous membrane function. The clinical findings in these patients are delineated and compared to patients with other forms of ectodermal dysplasia in the literature. [source] DROUGHT STRESS: Comparative Time Course Action of the Foliar Applied Glycinebetaine, Salicylic Acid, Nitrous Oxide, Brassinosteroids and Spermine in Improving Drought Resistance of RiceJOURNAL OF AGRONOMY AND CROP SCIENCE, Issue 5 2010M. Farooq Abstract Worldwide rice productivity is being threatened by increased endeavours of drought stress. Among the visible symptoms of drought stress, hampered water relations and disrupted cellular membrane functions are the most important. Exogenous use of polyamines (PAs), salicylic acid (SA), brassinosteroids (BRs), glycinebetaine (GB) and nitrous oxide (NO) can induce abiotic stresses tolerance in many crops. In this time course study, we appraised the comparative role of all these substances to improve the drought tolerance in rice (Oryza sativa L.) cultivar Super-Basmati. Plants were subjected to drought stress at four leaf stage (4 weeks after emergence) by maintaining soil moisture at 50 % of field capacity. Pre-optimized concentrations of GB (150 mg l,1), SA (100 mg l,1), NO (100 ,mol l,1 sodium nitroprusside as NO donor), BR (0.01 ,m 24-epibrassinolide) and spermine (Spm; 10 ,m) were foliar sprayed at five-leaf stage (5 weeks after emergence). There were two controls both receiving no foliar spray, viz. well watered (CK1) and drought stressed (CK2). There was substantial reduction in allometric response of rice, gas exchange and water relation attributes by drought stress. While drought stress enhanced the H2O2, malondialdehyde (MDA) and relative membrane permeability, foliar spray of all the chemicals improved growth possibly because of the improved carbon assimilation, enhanced synthesis of metabolites and maintenance of tissue water status. Simultaneous reduction in H2O2 and MDA production was also noted in the plants treated with these substances. Drought tolerance was sturdily associated with the greater tissue water potential, increased synthesis of metabolites and enhanced capacity of antioxidant system. Of all the chemicals, foliar spray with Spm was the most effective followed by BR. [source] Nitrosative stress induced cytotoxicity in Giardia intestinalisJOURNAL OF APPLIED MICROBIOLOGY, Issue 3 2003D. Lloyd Abstract Aims: To investigate the antigiardial properties of the nitrosating agents: sodium nitrite, sodium nitroprusside and Roussin's black salt. Methods and Results: Use of confocal laser scanning microscopy and flow cytometry indicated permeabilization of the plasma membrane to the anionic fluorophore, DiBAC4(3) [bis(1,3-dibutylbarbituric acid) trimethine oxonol]. Loss of plasma membrane electrochemical potential was accompanied by loss of regulated cellular volume control. Changes in ultrastructure revealed by electron microscopy and capacity for oxygen consumption, were also consequences of nitrosative stress. Roussin's black salt (RBS), active at micromolar concentrations was the most potent of the three agents tested. Conclusions: These multitargeted cytotoxic agents affected plasma membrane functions, inhibited cellular functions in Giardia intestinalis and led to loss of viability. Significance and Impact of the Study: Nitrosative damage, as an antigiardial strategy, may have implications for development of chemotherapy along with suggesting natural host defence mechanisms. [source] Metabolic syndrome and mitochondrial function: Molecular replacement and antioxidant supplements to prevent membrane peroxidation and restore mitochondrial function,JOURNAL OF CELLULAR BIOCHEMISTRY, Issue 6 2007Garth L. Nicolson Abstract Metabolic syndrome consists of a cluster of metabolic conditions, such as hypertriglyeridemia, hyper-low-density lipoproteins, hypo-high-density lipoproteins, insulin resistance, abnormal glucose tolerance and hypertension, that,in combination with genetic susceptibility and abdominal obesity,are risk factors for type 2 diabetes, vascular inflammation, atherosclerosis, and renal, liver and heart disease. One of the defects in metabolic syndrome and its associated diseases is excess cellular oxidative stress (mediated by reactive oxygen and nitrogen species, ROS/RNS) and oxidative damage to mitochondrial components, resulting in reduced efficiency of the electron transport chain. Recent evidence indicates that reduced mitochondrial function caused by ROS/RNS membrane oxidation is related to fatigue, a common complaint of MS patients. Lipid replacement therapy (LRT) administered as a nutritional supplement with antioxidants can prevent excess oxidative membrane damage, restore mitochondrial and other cellular membrane functions and reduce fatigue. Recent clinical trials have shown the benefit of LRT plus antioxidants in restoring mitochondrial electron transport function and reducing moderate to severe chronic fatigue. Thus LRT plus antioxidant supplements should be considered for metabolic syndrome patients who suffer to various degrees from fatigue. J. Cell. Biochem. 100: 1352,1369, 2007. © 2007 Wiley-Liss, Inc. [source] Photodynamic Effects of Antioxidant Substituted Porphyrin Photosensitizers on Gram-positive and -negative Bacteria,PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 2 2003Helena Ashkenazi ABSTRACT Photodynamic treatment of the gram-negative bacteria Escherichia coli B and Acinetobacter baumannii and the gram-positive bacterium Staphylococcus aureus was performed using two newly devised and synthesized antioxidant carrier photosensitizers (antioxidant carrier sensitizers-2 [ACS-2] and antioxidant carrier sensitizers-3 [ACS-3]), which are butyl hydroxy toluene and propyl gallate substituted haematoporphyrins, respectively. It was found that ACS-2 is less reactive than other photosensitizers previously used for the same purpose, whereas ACS-3 is very effective against the multidrug-resistant bacterium A. baumannii, causing its complete eradication at a low fluence (,7.5 J/cm) of blue light (407,420 nm) and a low concentration (10 ,M). At a higher fluence (,37.5 J/cm) complete eradication of E. coli B can be obtained under the same conditions. Furthermore, X-ray microanalysis and ultrastructural changes indicate that ACS-3, especially in the case of photodynamic treatment of A. baumannii, interferes with membrane functions and causes the inactivation of the bacterium. ACS-3 may be suggested as a specific photosensitization agent for photoinactivation of gram-negative bacteria. [source] Cell Subpopulation-related Volumetric Parameters: a Complementary Tool of the Modified Hypo-osmotic Swelling Test on Model of Boar SpermatozoaREPRODUCTION IN DOMESTIC ANIMALS, Issue 5 2000A. Petrounkina Content It is a general property of the intact animal cell to swell rapidly in response to hypo-osmotic conditions. The modified hypo-osmotic swelling test (HOS-test) is an indicative test to evaluate the integrity of the plasma membrane by means of an electronic cell counter, based on the relative increase of the cell volume in response to hypo-osmotic conditions. In this study the relationships between the osmotically induced changes of the cell volume of boar spermatozoa as determined by cell counter and the integrity of the membrane as determined by propidium iodide staining (PI) were studied. Boar sperm cell volume distributions were measured under iso-osmotic (300 mosmolar) conditions and after a hypo-osmotic stress (150 mosmolar). The relative volume shift of mean and modal volume were calculated as a proportion coefficient of modal and mean values of the cell volume distributions by transition from iso-osmotic to hypo-osmotic conditions. The volumetric parameters related to the different cell subpopulations were derived from the different peaks of cell volume distributions. PI-staining techniques were used for comparison. The values of the volume shift and of derived percentages of the osmotically inactive cells were correlated negatively and positively, respectively (p < 0.05) with the percentage of the PI-stained cells. This correlation indicates that a relationship exists between membrane functions of the different cell compartments (sperm head and tail) due to the circumstance that the increase of the cell volume in the HOS-test is associated with the morphological changes in the tail and the PI-staining is associated with the membrane integrity and permeability of the head region. The advantage of computer-assisted volume measurement is that a large number of cells (5000,50 000 spermatozoa) can be measured and evaluated during one procedure and in a very short time. The relative volume shift is a quantitative continuous parameter characterizing the osmotic reactivity and membrane functional competence of a cell population and of subpopulations within one ejaculate. This parameter could be useful to evaluate membrane functional competence rapidly and sensitively. Inhalt Es ist eine generelle Eigenschaft membranintakter tierischer Zellen, mit einer Volumenzunahme auf eine hypoosmotische Belastung zu reagieren. Der auf der relativen Vergrößierungdes Zellvolumens basierende modifizierte hypoosmotischeSchwelltest ist ein indikativer Test zur Beurteilung der Membranintegrität mittels eines elektronischen Partikelzählers. In dieser Studie wurden die Zusammenhänge zwischen der mittels der Propidiumjodid-Färbung bestimmten Zellmembranintegrität und den osmotisch induzierten Veränderungen des Zellvolumens von Eberspermien untersucht. Volumenverteilungen von Eberspermien wurden unter isoosmotischen (300 mosmolar) und hypoosmotischen (150 mosmolar) Bedingungen gemessen. Die relative Volumenverschiebung der modalen und mittleren Werte der Volumenverteilung wurde als Quotient aus Modalwerten der Zellvolumenverteilungen und des mittleren Zellvolumens beim Übergang von isotonen zu hypotonen Bedingungen berechnet. Die auf verschiedene Subpopulationen bezogenen volumetrischen Parameter werden aus den originalen Volumenverteilungen berechnet. Der Betrag der Zellvolumenzunahme und die aus den Volumenverteilungen bestimmten Anteile an Zellen mit beschädigter Geißielmembran korrelierten signifikant negativ bzw. positiv (p < 0,05) mit dem Anteil an den Zellen mit beschädigter Kopfmembran, der sich aus der Propidiumjodid-Färbung ergab. Es wird geschlossen, daßi im Verhalten zwischen den Membranen der verschiedenen Zellkompartimente (Spermienkopf und-Geißiel) ein Zusammenhang besteht. Die beschriebene Methode ermöglicht die Analyse großier Zellpopulationen (5.000,50.000 Zellen). Die relative Volumenverschiebung stellt einen quantitativen kontinuierlichen Parameter dar, der den Membranzustand der Eberspermien einer Spermatozoenpopulation und Subpopulationen innerhalb eines Ejakulates charakterisiert. Diese Parameter können zur schnellen und sensitiven Beurteilung der Membranzustandes eingesetzt werden. [source] | |||||||||||||