The activation of red blood cell transketolase in groups of patients especially at risk from thiamin deficiency

Erythrocyte transketolase activation by thiamin diphosphate has been studied in elderly patients with moderate or severe chronic dementia, acute alcoholic admissions and chronic alcoholics with evidence of brain damage, mostly of the Wernicke-Korsakoff type. Significantly more patients in each group than controls showed abnormal activation of transketolase, not only by 0.3 mM thiamin diphosphate (TDP) but also in further activation by increase to 3 mM. This indicated the presence in a proportion of the alcoholic and the demented patients of an abnormal enzyme variant, similar to that previously found in vitro. The modified transketolase activation test may warn not only of marginal thiamin deficiency but also independently, of susceptibility to brain damage in patients at risk.     

An assessment of the delayed hypersensitivity reaction to methylated bovine serum albumin in the mouse and its use in the evaluation of drug effects on cell mediated immune reactions

A delayed hypersensitivity (DH) reaction is induced by a sensitizing intradermal injection of methylated bovine serum albumin (MBSA) into the abdomen of mice and a subsequent challenge injection of MBSA into the hind paw. Paw volume increase is measured by mercury plethysmography. The conditions for sensitization have been investigated. Sensitization with a 0.25% MBSA emulsion resulted in a small but significant swelling of the paw following the challenge injection. The magnitude of the footpad response to the challenge injection was increased if the antigen administered in the sensitizing injection was emulsified with Freund's incomplete adjuvant. Incorporation ofMycobacterium butyricum in the emulsion greatly increased the footpad response if added at doses of 0.05 and 1 mg per animal. A higher dose (4 mg), however, resulted in a lower response. The time course of development of the delayed hypersensitivity reaction has been studied. An 8-day interval between sensitization and challenge resulted in a greater delayed hypersensitivity response than a shorter (3-day) or longer (15-, 21-, 28-day) interval. Cyclophosphamide (250 mg kg^–1) administered 3 days prior to the sensitizing injection of MBSA produced a modest enhancement of the DH reaction.On the basis of these studies a protocol for conducting the DH reaction to MBSA was established and the activity of drugs on processes underlying the sensitization phase of the reaction or processes underlying the elicitation phase of the reaction have been examined. Steroid and immunosuppressant drugs were found to inhibit the DH footpad response when dosed during the sensitization whereas several specific-anti-rheumatic and immunoactive compounds were without effect. Indomethacin and sudoxicam inhibited the DH reaction if dosed during the elicitation of the reaction but other non-steroidal anti-inflammatories tested did not significantly reduce the response. The clinically used anti-rheumatic drugsd-penicillamine and levamisole did not inhibit the elicitation phase of the DH response but niridazole at 100 mg kg^–1 did reduce the inflammatory response.This paper has been presented in part as a poster presentation to the British Pharmacological Society, 4–6 January 1978.     

Relationship between production of epidermal growth factor receptors, gene amplification, and chromosome 7 translocation in variant A431 cells

Synthesis of the epidermal growth factor (EGF) receptor has been analyzed in a series of variant A431 human epidermoid carcinoma cell clones reported to contain different amounts of EGF binding sites. The amount of EGF receptor protein, quantitated by immunoaffinity chromatography, and EGF receptor mRNA, quantitated by cDNA hybridization, were closely correlated to the extent of EGF receptor gene amplification. This correlation existed in variants selected for reduced EGF receptors and in revertants from those variants with increased EGF receptors. There was also a correlation between the frequency of translocation of chromosome 7, containing the EGF receptor gene, and EGF receptor protein. These results support gene amplification as the mechanism enhancing A431 cell EGF receptor protein and determining growth responses.     

Defibrination with ancrod in experimental chronic immune complex nephritis

The role of fibrin deposition in experimental (crescentic) nephritis in rabbits, due to chronic immune complex deposition induced by BSA, has been studied. Fibrin deposition was prevented and in such animals crescent formation inhibited, suggesting that, as in experimental nephritis due to anti-GBM antibodies, fibrin deposition plays a major pathogenetic role in epithelial cell proliferation. However, in defibrinated animals, mesangial and endothelial cell proliferation, polymorpho-nuclear leucocyte infiltration and impairment of renal function could still occur. These studies are further evidence that defibrination may be of benefit in the treatment of rapidly progressive glomerulonephritis in man.     

Molecular epidemiology of HIV-1 variants in the global AIDS pandemic: an update

The picture of HIV-1 genetic diversity in the global pandemic continues to evolve. Identification of new variants, including circulating and unique recombinant forms, recognition of new outbreaks and of changes in established epidemics, and characterization of growing numbers of full-length genomes provide a view of high dynamism and increasing complexity. The pervasive role of recombination as a major driving force in the generation of diversity in the HIV-1 pandemic is becoming evident, and is particularly visible in areas in which different genetic forms meet, referred to as "geographic recombination hotspots". The importance of superinfection and its impact on HIV-1 diversification and propagation is surfacing, although restrictions to superinfection are also apparent. Genetic diversity within subtypes is increasing over time and new geographically localized lineages deriving from point introductions are being recognized. Characterization of such variants may be of relevance to vaccine development and may allow the detection of intrasubtype recombination and superinfection. Recent studies supporting the correlation of HIV-1 clades to immune responses and to drug resistance-associated mutations lend increasing relevance to the role of molecular epidemiology as an essential tool in combating the AIDS pandemic. However, knowledge on the global HIV-1 genetic diversity and its implications is still far from adequate and a major scaling up of efforts is needed.     

No association between CHRNA7 microsatellite markers and attention-deficit hyperactivity disorder.

Attention-deficit hyperactivity disorder (ADHD) is a highly heritable, common psychiatric disorder of childhood that probably involves several genes. There are several lines of evidence suggesting that the nicotinic system may be functionally significant in ADHD. First, nicotine promotes the release of dopamine and has been shown to improve attention in adults with ADHD, smokers, and nonsmokers. Second, ADHD is a significant risk factor for early initiation of cigarette smoking in children and maternal cigarette smoking appears to be a risk factor for ADHD. Finally, animal studies in rats and monkeys also suggest that nicotine may be involved in attentional systems and locomotor activity. The nicotinic system has previously been studied in schizophrenia where the neuronal nicotinic acetylcholine receptor alpha 7 subunit gene (CHRNA7) has been implicated in decreased P50 inhibition and attentional disturbances in patients with schizophrenia and in many of their nonschizophrenic relatives. Three known microsatellite markers (D15S165, D15S1043, and D15S1360) near the nicotinic acetylcholine alpha 7 receptor gene, CHRNA7, were studied in 206 ADHD parent-proband trios of children aged 5-16 with ADHD according to DSM-IV criteria. Children with known major medical or psychiatric conditions or mental retardation (IQ < 70) were excluded from the study. Markers D15S165 and D15S1360 were in linkage disequilibrium. The extended Transmission Disequilibrium Test analyses demonstrated no evidence that variation at the microsatellite markers D15S1360, D15S1043, and D15S165 influences susceptibility to ADHD. However, it remains possible that the CHRNA7 gene and other nicotinic system genes may be involved in conferring susceptibility to ADHD.     

PTOV-1, a novel protein overexpressed in prostate cancer,shuttles between the cytoplasm and the nucleus and promotes entry into the S phase of the cell division cycle

PTOV1 was recently identified as a novel gene and protein during a differential display screening for genes overexpressed in prostate cancer. The PTOV1 protein consists of two novel protein domains arranged in tandem, without significant similarities to known protein motifs. By immunohistochemical analysis, we have found that PTOV1 is overexpressed in 71% of 38 prostate carcinomas and in 80% of samples with prostate intraepithelial neoplasia. High levels of PTOV1 in tumors correlated significantly with proliferative index, as assessed by Ki67 immunoreactivity, and associated with a nuclear localization of the protein, suggesting a functional relationship between PTOV1 overexpression, proliferative status, and nuclear localization. In quiescent cultured prostate tumor cells, PTOV1 localized to the cytoplasm, being excluded from nuclei. After serum stimulation, PTOV1 partially translocated to the nucleus at the beginning of the S phase. At the end of mitosis, PTOV1 exited the nucleus. Transient transfection of chimeric green fluorescent protein-PTOV1 forced the entry of cells into the S phase of the cell cycle, as shown by double fluorescent imaging for green fluorescent protein and for Ki67, and also by flow cytometry. This was accompanied by greatly increased levels of cyclin D1 protein in the transfected cells. These observations suggest that overexpression of PTOV1 can contribute to the proliferative status of prostate tumor cells and thus to their biological behavior.     

Effects of a brisk walk on lipoprotein lipase activity and plasma triglyceride concentrations in the fasted and postprandial states

This study aimed to determine whether changes in plasma heparin-releasable lipoprotein lipase (LPL) activity following a brisk walk were associated with decreases in fasting and/or postprandial triglyceride (TG) concentrations. Two groups of pre-menopausal women participated. In one group (fasting study group, n=10), TG concentrations and post-heparin plasma LPL activity were measured in the fasted state on two occasions: ~18 h after a 2-h treadmill walk at 50% maximal oxygen uptake (exercise trial); and after a day of no exercise (control trial). The other group (postprandial study group, n=9) undertook two oral fat tolerance tests (blood samples taken fasting and for 6 h after a high-fat meal), with plasma LPL activity measured 6 h after meal ingestion. Pre-conditions were the same as for the fasting study group (i.e. control and prior exercise). Prior exercise reduced fasting TG concentrations by 23 (7)% (fasting study group) [mean (SEM)] and by 18 (9)% (postprandial study group) (both P<0.05), and the postprandial TG response by 23 (6)% (postprandial study group) (P<0.01). Plasma LPL activity was not significantly increased by exercise in either the fasting or postprandial study groups. However, exercise-induced changes in both fasting and postprandial LPL activity were significantly correlated with the respective exercise-induced changes in fasting TG concentration and the postprandial TG response (r=−0.70 and −0.77 respectively, P<0.05 for both). These data suggest that increased LPL activity may contribute to the hypotriglyceridaemic effect of moderate exercise, although other mechanisms are also likely to be involved. Electronic Publication     

Identification of 21 novel glucokinase (GCK) mutations in UK and European Caucasians with maturity-onset diabetes of the young (MODY)

Maturity-onset diabetes of the young (MODY) resulting from mutations in the glucokinase (GCK) gene accounts for approximately 20% of MODY in the UK. We have performed fluorescent single stranded conformation polymorphism (F-SSCP) analysis or direct sequencing of the GCK gene in 212 patients referred as part of a research cohort or for diagnostic molecular genetic testing. Mutation screening has identified 43 different mutations in 61 individuals, of which 21 are novel. This report details the mutations identified and their associated clinical features.     

Ischemia-reperfusion in humans. Appearance of xanthine oxidase activity.

We evaluated effluent blood from extremities of human patients undergoing reconstructive surgical treatment, which is routinely accompanied by upper-extremity exsanguination and application of a tourniquet, resulting in total interruption of arterial blood flow to one upper extremity. After tourniquet release (reperfusion), there were immediate increases in the plasma levels of xanthine oxidase activity, uric acid, and histamine in the ipsilateral limb and much smaller increases, if any, in levels of the same materials in plasma obtained from the contralateral extremity. There was no detectable xanthine dehydrogenase activity in plasma from either limb. Plasma also contained evidence of products consistent with the formation of oxygen-derived free radicals, namely, the appearance predominantly in the reperfused limb of hemoglobin and fluorescent compounds. These data indicate for the first time in humans that ischemia-reperfusion events are associated with the appearance of xanthine oxidase activity and its products in the plasma effluent.