Biochemical and biophysical research communications
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Biochem. Biophys. Res. Commun. · Oct 1998
Case ReportsDiagnosis of mitochondrial disease: assessment of mitochondrial DNA heteroplasmy in blood.
Mitochondrial DNA (mtDNA) mutations are an important cause of neurological disease. The identification of causative mtDNA mutations may be particularly troublesome in blood where there are often low levels of mutant mtDNA. This is evident from a recent study in which heteroplasmic mtDNA mutations in cytochrome c oxidase genes were incorrectly thought to be linked to Alzheimer's disease. ⋯ Whilst there was no consistent decrease in the level of mtDNA heteroplasmy, we observed the coamplification of a novel mtDNA pseudogene from DNA samples extracted by a simple 'boiling' procedure using primers designed to screen for the tRNALeu(UUR) A3243G mutation. This pseudogene was readily amplified from DNA extracted from rho degrees (mtDNA-less) cells, confirming its nuclear location. We believe that mtDNA pseudogenes may therefore present significant difficulties in the accurate identification of pathogenic heteroplasmic mtDNA mutations in blood.
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Biochem. Biophys. Res. Commun. · Sep 1998
Autoxidation of pyridoxalated hemoglobin polyoxyethylene conjugate.
Hemoglobin-based therapeutics are currently in clinical trials in the United States and abroad as blood replacement solutions, nitric oxide scavengers, and radiation sensitizers. The potency of the therapeutics may be influenced by the oxidation state of the iron in the heme moiety. The oxidation state is dependent upon the physical environment of the molecule and is influenced by parameters such as the chemical nature of the hemoglobin therapeutic and its formulation. ⋯ The oxidation events were shown to be biphasic and were similar to those observed for purified human hemoglobin (HbAo). The initial fast oxidation events were modeled with first order rate constants at 37 degrees C and determined to be 0.022 hr-1 and 0.025 hr-1 for PHP and HbAo, respectively. The autoxidation of PHP was shown to be independent of concentration from approximately 5 to 100 mg/mL.
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Biochem. Biophys. Res. Commun. · Aug 1998
Activation of alphav beta3 integrin on human osteoclast-like cells stimulates adhesion and migration in response to osteopontin.
Integrins mediate cell adhesion and can induce different cellular responses, including changes in intracellular pH, changes and oscillation in intracellular free calcium, and protein phosphorylation on tyrosine. During bone resorption, the integrin alphav beta3 regulates adhesion of osteoclasts to bone extracellular matrix proteins, such us osteopontin (Opn). Adhesion via alphav beta3 is followed by osteoclast polarization onto the bone surface and by the onset of bone resorption. ⋯ Activation of alphav beta3 increased the efficiency of GCT23 adhesion to Opn by 2-fold. Furthermore, haptotactic migration on Opn was also enhanced about 40% compared to control. We propose that changes in the activation state of alphav beta3 may be a regulation point for osteoclasts during bone resorption.
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Biochem. Biophys. Res. Commun. · May 1998
An intestinal bacterial metabolite of ginseng protopanaxadiol saponins has the ability to induce apoptosis in tumor cells.
Our previous study demonstrated that the in vivo anti-metastatic effect induced by oral administration of ginseng protopanaxadiol saponins was mediated by their metabolic component M1, and that the growth, invasion and migration of tumor cells were inhibited by M1 but not by ginsenosides. Here we investigated the inhibitory mechanism of M1 on the growth of tumor cells. M1 inhibited the proliferation of B16-BL6 mouse melanoma cells in a time- and dose-dependent manner, with accompanying morphological changes at the concentration of 20 microM. ⋯ Fluorescence microscopy revealed that dansyl M1 entered the cytosol and quickly reached the nuclei (approximately 15 min). Western blot analysis revealed that M1 rapidly up-regulated the expression of p27Kip1, but down-regulated the expression of c-Myc and cyclin D1 in a time-dependent manner. Thus, the regulation of apoptosis-related proteins by M1 is responsible for the induction of apoptotic cell death, and this probably leads to the anti-metastatic activity in vivo.
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Biochem. Biophys. Res. Commun. · Mar 1998
Increased pentosidine, an advanced glycation end product, in plasma and synovial fluid from patients with rheumatoid arthritis and its relation with inflammatory markers.
Pentosidine is an advanced glycation end product (AGE) formed by combined processes of glycation and oxidation (glycoxidation) between carbohydrate-derived carbonyl group and protein amino group. Recent studies demonstrated the increased pentosidine levels not only in diabetic patients with hyperglycemia but also in normoglycemic uremic patients due to increased oxidative stress. Rheumatoid arthritis (RA) is a state of increased oxidative stress associated with chronic inflammation. ⋯ Among markers of inflammation and matrix destruction, pentosidine levels in plasma from RA patients were correlated with the levels of C-reactive protein (CRP), erythrocyte sedimentation rate, white blood cell count, and platelet count. Multiple stepwise regression analysis reveals an independent influence of CRP on plasma pentosidine levels. In conclusion, pentosidine levels are significantly higher in plasma and synovial fluid from RA patients and may be useful as a biomarker of chronic inflammation in RA patients.