The lactate dehydrogenase activity and isoenzyme pattern of normal and hypokinetic human tendons

Summary The LDH specific activity and the LDH isoenzyme pattern of eleven pairs of different normal tendons were compared with hypokinetic tendons. The LDH specific activity of hypokinetic tendons was 13–66% of the specific activity of normal tendons. The isoenzyme pattern of hypokinetic tendons altered in such a way that — with one exception — the ratio of LDH-5 and LDH-4 decreased and the ratio of LDH-1, LDH-2, and LDH-3 increased and, as a consequence, the amount of the M subunit decreased.     

Systematic review on the treatment of deceased organ donors

Background

Currently, there is no consensus on which treatments should be a part of standard deceased-donor management to improve graft quality and transplantation outcomes. The objective of this systematic review was to evaluate the effects of treatments of the deceased, solid-organ donor on graft function and survival after transplantation.

猕猴急性脑缺血大脑细胞及线粒体内几种酶活性和cAMP的变化

给10只猕猴结扎4根动脉造成急性脑缺血15分钟及30分钟后,大脑细胞线粒体内的磷酸肌酸激酶活性增高,但缺血达60分时酶活性较15分钟的降低。线粒体内的异柠檬酸脱氢酶活性降低,缺血时间越长,降低越明显。大脑细胞浆内的乳酸脱氢酶活性开始增高以后降低。缺血15分钟后大脑皮层组织中的cAMP含量减少,30分钟后又升高。对上述改变的可能机制作了讨论。     

Lactate dehydrogenase isoenzymes in tumours of the nervous system

Summary The variations in the isoenzymes of lactic acid dehydrogenase have been studied in a series of tumours of the nervous system. From these the ratio of heart muscle component to skeletal muscle component (the H/M ratio) has been calculated and compared with the H/M ratio of a variety of regions of normal brain. Oligodendrogliomata were found to have a very high H/M ratio. There was a decrease in the ratio with increasing degrees of de-differentiation of all tumours studied. However the H/M ratio does not appear directly related to the rate of growth irrespective of the tissue of origin of the tumour. Tumours derived from different tissues appear to have their own range of ratios. Tumour cyst fluids showed similar ratios to their parent tumours.     

Acetaldehyde production and other ADH-related characteristics of aerobic bacteria isolated from hypochlorhydric human stomach

BACKGROUND: Acetaldehyde is a known local carcinogen in the digestive tract in humans. Bacterial overgrowth in the hypochlorhydric stomach enhances production of acetaldehyde from ethanol in vivo after alcohol ingestion. Therefore, microbially produced acetaldehyde may be a potential risk factor for alcohol-related gastric and cardiac cancers. This study was aimed to investigate which bacterial species and/or groups are responsible for acetaldehyde formation in the hypochlorhydric human stomach and to characterize their alcohol dehydrogenase (ADH) enzymes. METHODS: After 7 days of treatment with 30 mg of lansoprazole twice a day, a gastroscopy was performed on eight volunteers to obtain hypochlorhydric gastric juice. Samples were cultured and bacteria were isolated and identified; thereafter, their acetaldehyde production capacity was measured gas chromatographically by incubating intact bacterial suspensions with ethanol at 37 degrees C. Cytosolic ADH activities, Km values, and protein concentration were determined spectrophotometrically. RESULTS: Acetaldehyde production of the isolated bacterial strains (n = 51) varied from less than 1 to 13,690 nmol of acetaldehyde/10(9) colony-forming units/hr. ADH activity of the strains that produced more than 100 nmol of acetaldehyde/10(9) colony-forming units/hr (n = 23) varied from 3.9 to 1253 nmol of nicotinamide adenine dinucleotide per minute per milligram of protein, and Km values for ethanol ranged from 0.65 to 116 mM and from 0.5 to 3.1 M (high Km). There was a statistically significant correlation (r = 0.64, p < 0.001) between ADH activity and acetaldehyde production from ethanol in the tested strains. The most potent acetaldehyde producers were Neisseria and Rothia species and Streptococcus salivarius, whereas nearly all Stomatococcus, Staphylococcus, and other Streptococcus species had a very low capacity to produce acetaldehyde. CONCLUSIONS: This study demonstrated that certain bacterial species or groups that originate from the oral cavity are responsible for the bulk of acetaldehyde production in the hypochlorhydric stomach. These findings provide new information with the respect to the local production of carcinogenic acetaldehyde in the upper digestive tract of achlorhydric human subjects.     

Molecular Control of the Hyaluronan Biosynthesis

Hyaluronan (HA) is the only unsulfated glycosaminoglycan (GAG) composed of repeating units of D-glucuronic acid and N-acetylglucosamine. The amount and the molecular weight of HA are important factors that regulate the physiology and pathology in several mammalian tissues. In fact hydrated HA makes ECM an ideal environment in which cells can move and proliferate. HA interacting with several receptors at the cellular level plays a critical role in signal transduction responses. The control of the HA synthesis is therefore a critical aspect in ECM and cells biology, but so far the information about this question is scanty. The synthesis of HA is due to several enzymes activities which not only involves its synthetic enzymes on the membranes of the cells (HA synthases 1, 2, 3, isoforms) but also the cytoplasmatic enzymes producing the UDP-sugar precursors. The UDP-sugars availability in cytoplasm is a critical point for the GAG synthesis and it seems to affect particularly the HA production. Eventually, the activity control of the enzymes involved in HA metabolism is obtained throughout both enzyme amount and their postsynthetic covalent modification, as phosphorylation. In fact, it was recently reported that HA synthase 3 may be phosphorylated after specific stimuli, and an increasing body of evidence supports the idea that the synthetic pathway of HA may be carefully regulated in all steps.