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Metabolic Features (metabolic + feature)

Distribution by Scientific Domains

Medical Sciences	75%

Selected Abstracts

Induction of CD44 cleavage in articular chondrocytes

ARTHRITIS & RHEUMATISM, Issue 5 2010
Nobunori Takahashi
Objective The hyaluronan receptor CD44 provides chondrocytes with a mechanism for sensing and responding to changes in the extracellular matrix. The purpose of this study was to document the fragmentation and loss of CD44 and to determine the likely mechanisms involved. Methods A polyclonal anti-CD44 cytotail antibody was generated to detect CD44 fragmentation by Western blot analysis. Chondrocytes were isolated from human or bovine articular cartilage. Primary articular chondrocytes were treated with interleukin-1, (IL-1,), hyaluronan oligosaccharides, or phorbol myristate acetate or were passaged and subcultured in monolayer to induce dedifferentiation. Conditions that altered the capacity of CD44 to transit into lipid rafts, or pharmacologic inhibitors of metalloproteinase or ,-secretase activity were used to define the mechanism of fragmentation of CD44. Results Chondrocytes from osteoarthritic cartilage exhibited CD44 fragmentation as low molecular mass bands, corresponding to the CD44-EXT and CD44-ICD bands. Following dedifferentiation of chondrocytes or treatment of primary chondrocytes with hyaluronan oligosaccharides, IL-1,, or phorbol myristate acetate, CD44 fragmentation was enhanced. Subsequent culture of the dedifferentiated chondrocytes in 3-dimensional alginate beads rescued the chondrocyte phenotype and diminished the fragmentation of CD44. Fragmentation of CD44 in chondrocytes was blocked in the presence of the metalloproteinase inhibitor GM6001 and the ,-secretase inhibitor DAPT. Conclusion CD44 fragmentation, consistent with a signature pattern reported for sequential metalloproteinase/,-secretase cleavage of CD44, is a common metabolic feature of chondrocytes that have undergone dedifferentiation in vitro and osteoarthritic chondrocytes. Transit of CD44 into lipid rafts may be required for its fragmentation. [source]

Studies of relationships between the GLUT10 Ala206Thr polymorphism and impaired insulin secretion

DIABETIC MEDICINE, Issue 7 2005
C. S. Rose
Abstract Aims This study aimed to investigate if the previously observed association between the GLUT10 Ala206Thr polymorphism and variation in fasting and oral glucose-induced serum insulin concentrations could be replicated in a large-scale population-based cohort of Danish whites. Methods The GLUT10 Ala206Thr polymorphism was genotyped in a case-control study of 880 Type 2 diabetic patients and 4372 glucose-tolerant control subjects. The latter group was also enrolled in an assessment of fasting and post-OGTT circulating levels of plasma glucose and serum insulin in relation to genotype. The variant was genotyped by analysis of PCR-generated primer extension by matrix-assisted laser desorption/ionization time-of-flight analysis. Results The Ala206Thr variant was equally frequent among Type 2 diabetic patients and glucose-tolerant subjects (P = 0.9) and there was no difference in the distribution of genotype groups (P = 1.0). In the 4372 glucose-tolerant subjects there was no statistically significant association between the polymorphism and levels of fasting and post-oral glucose tolerance test plasma glucose and serum insulin along with the insulinogenic index and the homeostasis model of assessment for insulin resistance and insulin secretion. Likewise, in an age-stratified subgroup comprising 1264 subjects, we observed no relationships between the GLUT10 polymorphism and the selected metabolic features. Conclusions The GLUT10 Ala206Thr polymorphism is not associated with Type 2 diabetes in the Danish population. Furthermore, in the present large-scale cohort, the polymorphism does not associate with phenotypes such as fasting and oral glucose-induced levels of plasma glucose and serum insulin. [source]

Serum ghrelin, leptin and resistin levels in adolescent girls with polycystic ovary syndrome

JOURNAL OF OBSTETRICS AND GYNAECOLOGY RESEARCH (ELECTRONIC), Issue 4 2008
Aysun Bideci
Abstract Aim:, The aim of the present study was to investigate the levels of leptin, resistin and ghrelin in polycystic ovary syndrome (PCOS), and to assess their possible correlations with the hormonal and metabolic features of PCOS. Methods:, Sixteen obese (ObPCOS) and 12 lean (LeanPCOS) subjects with PCOS and 19 obese control subjects were enrolled in the study. Results:, Ghrelin, leptin and resistin concentrations were similar between groups when body mass index (BMI) was used as a covariate (P > 0.05). Mean androgen, SHBG, luteinizing hormone (LH) levels and luteinizing hormone/follicle-stimulating hormone (LH/FSH) ratio tended to be similar between polycystic ovary syndrome (PCOS) groups. However, when compared with the control group, SHBG was lower and androgen, LH levels and LH/FSH ratio were higher in the PCOS groups. Free testosterone levels significantly correlated with resistin (r = ,0.38), SHBG correlated significantly with body mass index (BMI) (r = ,0.45) and resistin (r = ,0.67), LH/FSH ratio was significantly correlated with ghrelin (r = ,0.52) and estradiol (E2) levels (r = 0.51). Conclusion:, ObPCOS and LeanPCOS groups having higher LH/FSH ratios and lower SHBG levels suggest that there could be factors other than adiposity responsible for the clinical features of PCOS patients. In the light of our results, those factors can be suggested as ghrelin and E2 for the elevated LH/FSH ratio and resistin for the lowered SHBG. [source]

A single nutrient feed supports both chemically defined NS0 and CHO fed-batch processes: Improved productivity and lactate metabolism

BIOTECHNOLOGY PROGRESS, Issue 5 2009
Ningning Ma
Abstract A chemically defined nutrient feed (CDF) coupled with basal medium preloading was developed to replace a hydrolysate-containing feed (HCF) for a fed-batch NS0 process. The CDF not only enabled a completely chemically defined process but also increased recombinant monoclonal antibody titer by 115%. Subsequent tests of CDF in a CHO process indicated that it could also replace the hydrolysate-containing nutrient feed in this expression system as well as providing an 80% increase in product titer. In both CDF NS0 and CHO processes, the peak lactate concentrations were lower and, more interestingly, lactate metabolism shifted markedly from net production to net consumption when cells transitioned from exponential to stationary growth phase. Subsequent investigations of the lactate metabolic shift in the CHO CDF process were carried out to identify the cause(s) of the metabolic shift. These investigations revealed several metabolic features of the CHO cell line that we studied. First, glucose consumption and lactate consumption are strictly complementary to each other. The combined cell specific glucose and lactate consumption rate was a constant across exponential and stationary growth phases. Second, Lactate dehydrogenase (LDH) activity fluctuated during the fed-batch process. LDH activity was at the lowest when lactate concentration started to decrease. Third, a steep cross plasma membrane glucose gradient exists. Intracellular glucose concentration was more than two orders of magnitude lower than that in the medium. Fourth, a large quantity of citrate was diverted out of mitochondria to the medium, suggesting a partially truncated tricarboxylic acid (TCA) cycle in CHO cells. Finally, other intermediates in or linked to the glycolytic pathway and the TCA cycle, which include alanine, citrate, isocitrate, and succinate, demonstrated a metabolic shift similar to that of lactate. Interestingly, all these metabolites are either in or linked to the pathway downstream of pyruvate, but upstream of fumarate in glucose metabolism. Although the specific mechanisms for the metabolic shift of lactate and other metabolites remain to be elucidated, the increased understanding of the metabolism of CHO cultures could lead to future improvements in medium and process development. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009 [source]