Standardisation of 31phosphorus-nuclear magnetic resonance spectroscopy determinations of high energy phosphates in humans

A procedure is described for standardising the determination of adenosine 5-triphosphate and phosphocreatine concentration ([ATP] and [PC], respectively, in absolute arbitrary units) in human muscle by nuclear magnetic resonance (NMR) spectroscopy. The individual ³¹phosphorus (²¹P)-NMR spectra obtained on equal hemispherical tissue volumes (muscle plus skin and fat) were corrected for the thickness of the skin and of the subcutaneous fat. The volumes investigated were standardised using an external reference. The procedure described made possible the comparison of high energy phosphate concentrations among different subjects. It was applied to the assessment of [ATP] and [PC] in four groups of sedentary subjects (children, and adults aged 20–35, 35–50 and over 50 years), and in a group of athletes (volleyball players). The [ATP] and [PC] were not statistically different in the groups investigated.     

Examination of Streptococcus mutans for immunoglobulin G Fc reactivity.

Representative strains of oral streptococci were tested for Fc immunoglobulin G (IgG) reactivity by two different techniques, agglutination of rabbit-IgG sensitized sheep erythrocytes and uptake of human and rabbit 125I-radiolabeled IgG. None of the S. mutans serotypes a through e reacted with the Fc region of either human or rabbit IgG. Additionally, other streptococci such as S. sanguis, S. salivarius, S. faecalis, and S. mitis failed to show appreciable Fc reactivity as assayed by these techniques. The group A, C, and G streptococci, previously shown to possess Fc reactivity, proved to be reactive in these experiments, as did a protein A-containing strain of Staphylococcus aureus.     

Frequency of the erythrogenic toxin B and C genes (speB and speC) among clinical isolates of group A streptococci.

DNA probes corresponding to the internal region of the erythrogenic toxin B and C genes, speB and speC, were used in hybridization studies with clinical isolates of Streptococcus pyogenes to determine the frequency of occurrence of these genes in a large population of group A streptococci. More than 500 strains from different geographical locations throughout the world were used in this study. The results from colony-lift hybridization experiments indicated that the frequency of occurrence of each toxin gene among all of these strains was 100% for speB and 50% for speC. Division of these strains into subgroups of general group A strains and strains associated with scarlet fever or rheumatic fever resulted in a frequency of occurrence of speC of about 50% for all subgroups. The speC gene was found to be more frequently associated with serotype M2, M4, and M6 strains and less frequently associated with serotype M1, M3, and M49 strains. The results from a similar study with the speA gene have been previously reported (C.-E. Yu and J.J. Ferretti, Infect. Immun. 57:3715-3719, 1989).     

Expression of gtfS is essential for normal insoluble glucan synthesis by Streptococcus downei.

The gtfI and gtfS genes of Streptococcus downei were investigated to determine the contribution of the respective enzymes to glucan production in the presence and absence of other glucosyltransferases. Extracts of Escherichia coli expressing cloned gtfS produced a short linear dextran from sucrose which could act as a primer for insoluble glucan synthesis when mixed with extracts of a strain expressing recombinant gtfI. To elucidate the contribution of gtfS to glucan production by S. downei, a mutant was constructed by insertionally inactivating gtfS. S. downei (gtfS mutant) colonies exhibited a marked phenotypic change on sucrose-containing media and a decreased ability to adhere to glass and produced no detectable water-insoluble glucan. These experiments confirm that expression of gtfS is essential for normal insoluble glucan synthesis by S. downei.     

Human mini-chromosomes in mouse embryonal stem cells

We have introduced human mini-chromosomes of 4 Mb and approximately 15 Mb in size into mouse embryonal stem cells. Although these human mini- chromosomes are stable in hamster and chicken cells, they re-arrange or segregate aberrantly in the embryonal stem cells and are rapidly lost in the absence of selection. However, one of the mini-chromosomes re- arranged, acquired mouse centromeric sequences and was then stably maintained for at least 60 population doublings in culture. This mini- chromosome, which is 4 Mb in size, is a candidate for a mouse germ line chromosome vector.      

Percutaneous nephrostomy - recovered renal-function in 50 obstetric and gynecologic patients undergoing percutaneous nephrostomy

Percutaneous nephrostomy (PN) will rapidly correct renal failure due to ureteral obstruction. Complications of the procedure are few and the procedure can be quickly accomplished on an outpatient basis using local anesthesia. A retrospective review of fifty patients who underwent PN led to derivation of a formula which predicts the expected degree of correction of renal function. Measurement of renal intracalyceal pressures at the time of PN was not helpful in predicting-outcome.     

Factor V Leiden and G20210A prothrombin mutation and the risk of subclavian vein thrombosis in patients with breast cancer and a central venous catheter.

BACKGROUND: To analyze the influence of the prothrombotic gene mutation factor V G1691A (factor V Leiden) and prothrombin G20210A on the risk of a first episode of catheter-related deep venous thrombosis (DVT) in a group of patients with breast cancer treated with chemotherapy. PATIENTS AND METHODS: Between January 1999 and February 2001, the occurrence of a first symptomatic DVT was investigated in a cohort of 300 consecutive patients with locally advanced or metastatic breast cancer treated at a single institution with fluorouracil-based chemotherapy, administered continuously through a totally implanted access port. A nested case-control study included 25 women (cases) with catheter-related DVT and 50 controls without DVT matched with cases for age, identical chemotherapy, stage of disease and prognostic features. The G1691A factor V and G20210A prothrombin mutation genotypes were analyzed. RESULTS: Five cases [20%; 95% confidence interval (CI) 9% to 39%)] and two controls (4%; 95% CI 1% to 14%) were heterozygous carriers of G1691A factor V (P = 0.04). The age-adjusted odds ratio for catheter-related DVT was 6.1 (95% CI 1.1-34.3). Only one patient (case) had the G20210A prothrombin gene mutation. Time from start of chemotherapy infusion to DVT was not significantly different between patients with (median 31 days) and without (median 43 days) G1691A factor V mutation (P = 0.6). CONCLUSIONS: Factor V Leiden carriers with locally advanced or metastatic breast cancer have an increased risk of developing catheter-related DVT during chemotherapy.