Determination of microplastics in sediment, water, and fish across the Orange-Senqu River basin.

Microplastics are increasingly recognised as posing a significant environmental threat across systems. Their pervasive presence in freshwater poses a serious concern, given the heavy reliance of both humans and biodiversity on healthy, functioning freshwater ecosystems. Acknowledgment of the potential risks led the transboundary Orange-Senqu River Commission (ORASECOM) to include sampling for microlitter (primarily microplastics) in riverine sediment, surface water, and fishes, across Southern Africa as part of the third Joint Basin Survey (JBS3) in 2021.

Reaction dynamics and residue identification of haemoglobin modification by acrolein, a lipid-peroxidation by-product.

Background: Lipid hydroperoxides decompose to reactive aldehydes, such as acrolein. Measurement of oxidative stress markers in the clinic could improve risk stratification for patients.

Methods: To aid the development of diagnostic oxidative stress markers, we defined the acrolein modifications of haemoglobin using mass spectrometry.

Molecular basis of a redox switch: molecular dynamics simulations and surface plasmon resonance provide insight into reduced and oxidised angiotensinogen.

Angiotensinogen fine-tunes the tightly controlled activity of the renin-angiotensin system by modulating the release of angiotensin peptides that control blood pressure. One mechanism by which this modulation is achieved is via angiotensinogen's Cys18-Cys138 disulfide bond that acts as a redox switch. Molecular dynamics simulations of each redox state of angiotensinogen reveal subtle dynamic differences between the reduced and oxidised forms, particularly at the N-terminus.

31° South: The physiology of adaptation to arid conditions in a passerine bird.

Arid environments provide ideal ground for investigating the mechanisms of adaptive evolution. High temperatures and low water availability are relentless stressors for many endotherms, including birds; yet birds persist in deserts. While physiological adaptation probably involves metabolic phenotypes, the underlying mechanisms (plasticity, genetics) are largely uncharacterized.

Plasma levels of soluble VEGF receptor isoforms, circulating pterins and VEGF system SNPs as prognostic biomarkers in patients with acute coronary syndromes.

Background: Development of collateral circulation in coronary artery disease is cardio-protective. A key process in forming new blood vessels is attraction to occluded arteries of monocytes with their subsequent activation as macrophages. In patients from a prospectively recruited post-acute coronary syndromes cohort we investigated the prognostic performance of three products of activated macrophages, soluble vascular endothelial growth factor (VEGF) receptors (sFlt-1 and sKDR) and pterins, alongside genetic variants in VEGF receptor genes, VEGFR-1 and VEGFR-2.

Seasonal behavioral responses of an arid-zone passerine in a hot environment.

Many arid-zone animals have to forage under extremely hot conditions to maintain water and energy balance. The effect of high air temperatures (T) on the behavioral patterns of small endothermic animals-characterized by their high energy and water demands-will provide a valuable framework for understanding species vulnerability to climate warming. We determined the seasonal behavioral responses to changes in T in a~10-g arid-zone passerine, the rufous-eared warbler (Malcorus pectoralis), in the Karoo semi-desert, South Africa.

The effect of simvastatin and bezafibrate on bile composition and gall-bladder emptying in female non-insulin-dependent diabetics.

Female non-insulin-dependent diabetics have a high prevalence of gallstones. Treatment of hyperlipidaemia in these patients may modify the risk. Seventeen female non-insulin-dependent diabetics (age 35-65) were treated with simvastatin (n = 10) or bezafibrate (n = 7) and had the cholesterol saturation index (CSI) of bile and gall-bladder emptying measured before and after 3 months therapy.

Effect of phospholipase C on cholesterol solubilization in model bile. A concanavalin A-binding nucleation-promoting factor from human gallbladder bile.

Human bile contains a phospholipase C activity. To examine its pathophysiological importance, the effect of phospholipase C on the dynamics of lipid solubilization and nucleation (cholesterol crystal formation) were investigated in model bile. Phospholipase C from gallbladder bile from patients with gallstones was partially purified by competitively eluting from a concanavalin A (con A)-Sepharose (Sigma, St.

Nucleation of cholesterol crystals from native bile and the effect of protein hydrolysis.

Nucleation time represents the terminal step in in vitro studies examining bile lithogenicity. Because of the concern that residual microcrystals, left after ultracentrifugation, may be responsible for the rapid nucleation time of gallbladder bile from patients with cholesterol gallstones, we have included a final filtration step. However, we found this procedure to considerably lengthen the nucleation time of abnormal biles.

Comparative analysis of cholesterol transport in bile from patients with and without cholesterol gallstones.

Aggregation of cholesterol-phospholipid vesicles in supersaturated biles precedes cholesterol crystal formation. In this study we examined the relationship between the percentage of cholesterol carried by vesicles and/or their composition and the propensity to form cholesterol crystals (nucleation time). Bile (common bile duct, gallbladder and T-tube) was obtained from patients with and without gallstones.

Phospholipase C and diacylglycerol lipase in human gallbladder and hepatic bile.

A phospholipase C in bile, free of bacterial infection, has recently been identified from cholesterol gallstone patients. Because of the importance of phosphatidylcholine in solubilizing cholesterol in bile, this study further investigates the metabolism of phosphatidylcholine in delipidated gallbladder and common bile duct biles. Phospholipase C activity, as measured by the release of phosphoryl[3H]choline from the substrate 1,2-dipalmitoyl-sn-glycero-3-phospho [N-methyl-3H]choline, was identified in both hepatic and gallbladder biles.

Apolipoprotein localization in the human bile duct and gallbladder.

Apolipoproteins AI, AII and B were identified in the normal and pathological human bile duct and the gallbladder epithelium using an avidin-biotin immunoperoxidase technique. Small intestine and stomach sections served as positive and negative controls respectively. Staining was focal for apolipoproteins AI and AII, and continuous for apolipoprotein B.

The effect of ethanol on phospholipid metabolism in rat pancreas.

The phospholipid effect involves agonist-induced breakdown of phosphatidyl inositol (or polyinositides) generating second messengers followed by increased incorporation of 32P during the resynthetic phase of the cycle. Ethanol, an aetiological factor in pancreatitis, has been shown to have various effects on pancreatic secretion. In this study ethanol decreased the incorporation of 32P into phosphatidyl inositol but had no effect on the stimulated breakdown of prelabelled phosphatidyl inositol.

Identification of a phosphatidylcholine active phospholipase C in human gallbladder bile.

This study describes the identification of a phospholipase C activity against phosphatidylcholine in delipidated human gallbladder bile. All biles were obtained from cholesterol gallstone patients and were negative on bacterial culture. The biliary enzyme was inhibited by EDTA and had a pH optimum of between 7-8.

The effect of ethanol on enzyme synthesis and secretion in isolated rat pancreatic lobules.

This study investigates the effect of ethanol on enzyme synthesis and secretion in rat pancreatic lobules. Ethanol caused a dose-dependent inhibition of 3H-leucine incorporation into total protein. Examination of the time dependence showed that ethanol inhibited protein synthesis at each time point.

Biliary secretion of cefoperazone and its inter-relationship with bile acid transport in the rat.

Cefoperazone is a third generation cephalosporin which is secreted predominantly in bile. This study set out to examine the effect of stimulating bile choleresis on the biliary secretion of cefoperazone. Stimulation of both bile acid-dependent and independent bile flow (phenobarbitone pretreatment) hastened the peak appearance of a pulse of cefoperazone into bile.

Inhibition of biliary phospholipid and cholesterol secretion by cefoperazone.

The effect of cefoperazone, a third-generation cephalosporin, on biliary lipid secretion in rats was examined. Rats were anesthetized with ether and the mid-lumbar vein and common bile duct cannulated. Bile acid secretion was maintained by intravenous taurocholic acid infusion (28 mumol/hr).

The incorporation of [myo-2-3H] inositol into phosphatidyl inositol of stimulated rat pancreas.

The 'phospholipid effect' involves agonist induced breakdown of phosphatidyl inositol (PI) or its phosphorylated derivates with increased incorporation of 32P or [myo-2-3H] inositol during resynthesis. In rat pancreas pancreozymin and bethanecol resulted in the standard dose dependent increased incorporation of 32P into PI which was paralleled by increased amylase secretion. By contrast the incorporation of [myo-2-3H] inositol into PI was significantly decreased by pancreozymin whereas bethanecol had no effect.

Distribution of biliary cholesterol between mixed micelles and nonmicelles in relation to fasting and feeding in humans.

To further investigate the nonmicelle mode of cholesterol transport in human bile, we examined its levels in relation to fasting and feeding. T-tube bile samples were collected (for 30 min) every 4 h over a 24-h period. All patients (3 with cholesterol gallstones; 1 with pigment stone) had their T tube clamped for a minimum of 4 days before the study to allow the bile acid pool to replete.

Solubilisation of cholesterol in human bile.

Two non-disruptive separation techniques (gel filtration, and CsCl density gradient ultracentrifugation) were used to characterise the mode of cholesterol transport in human bile. Both methods showed that biliary cholesterol is solubilised as a high--Mr non-micelle (lipoprotein) complex as well as the mixed micelle. The lipoprotein complex was separated between the densities 1.

Lithocholate detoxification and biliary secretion in the rat.

To define the efficiency of hepatic detoxification, 14C lithocholate in combination with taurocholate was continuously infused intravenously into rats until steady-state. Quantitation of hepatic radiolabelled bile acid under these conditions showed only 11% of total liver bile acid was unmetabolised, indicating very efficient detoxification of lithocholate, in its most hepatotoxic state. Interestingly we found the rate for each bile acid to reach steady-state differed.