Biomedical subjects

J Steele

Publications and source records attributed to J Steele.

At least 73 records · Page 4Linked to original sources

PubMed1986

Subdivision of daughter strains of bacille Calmette-Guérin (BCG) according to secreted protein patterns.

In order to identify proteins secreted by live organisms, daughter strains of the Bacillus Calmette-Guérin (BCG) were grown for 4-7 d in a defined medium containing [35S]methionine. Secreted components were then separated by polyacrylamide gel electrophoresis under both denaturing and non-denaturing conditions, and analysed by autoradiography and in an Ambis beta-scanner. The results indicate that BCG daughter strains can be subdivided into two groups according to their secretion of a 46 kDa protein dimer consisting of two similar 23 kDa subunits. High-producer strains (Japanese, Brazilian and Russian) secrete very large quantities of this material, which constitutes approximately 23% of all secreted protein. These findings correlate with earlier studies in which degradation products of the protein dimer may have been identified, and with the data from patterns of cell wall lipids.

Bacterial Proteins↗

PubMed1986

Prevalence and specificity of the enhancing effect of three types of interleukin 2 on T cell responsiveness in 97 lepromatous leprosy patients of mixed ethnic origin.

Peripheral blood mononuclear cells from 97 predominantly lepromatous leprosy patients and 11 control subjects were tested in a lymphoproliferative assay for response to Mycobacterium leprae (whole and sonicated), and sonicated M. vaccae, M. tuberculosis, and M. scrofulaceum, in the presence and absence of three types of interleukin 2 (IL-2) (crude, purified, and recombinant). IL-2 enhanced the response to sonicated M. tuberculosis and M. leprae organisms more often in patients than in control subjects, but not significantly so and only in a minority of patients. This effect was significantly more common (though still only found in a minority of 46%) using M. leprae organisms as antigen, than when using sonicates of M. leprae (19%) or M. vaccae (19%). However it was nearly as frequent using sonicated M. tuberculosis, or M. scrofulaceum. Thus in only nine patients was the effect specific to M. leprae. Enhancement by IL-2 could not be related to the type of IL-2 used, the dose of antigen, or the amount of endogenous IL-2 released by the cells tested. Similarly it was not related to the extent to which IL-2 caused increased background proliferation in control wells, which occurred to an equal extent using cells from control subjects, nor was it related to the extent of antigen-driven proliferation. The data have also been analysed in relation to duration of disease (50 years to a few weeks) and ethnic origin. No correlations have been revealed. Thus enhancement by IL-2 of the lymphoproliferative response to mycobacterial antigens does occur using cells from lepromatous leprosy patients, but it is found in a minority of patients, it is not specific to M. leprae, and can occur with cells from normal donors.

Antigens, Bacterial↗

PubMed1986

Vitamin D3, gamma interferon, and control of proliferation of Mycobacterium tuberculosis by human monocytes.

Previous studies have shown that recombinant interferon gamma (IFN-gamma), crude T cell supernatants, or appropriate T-cell lines can cause total inhibition of the growth of M. tuberculosis inside murine peritoneal macrophages. In similar experiments with human monocytes much smaller effects are seen. This could be due to the relative immaturity of these cells. Because dihydroxy vitamin D3 (1,25-(OH)2 D3) can cause phenotypic differentiation of immature leukemic lines into macrophage-like cells, we have explored the possibility that exposure to cholecalciferol metabolites in vitro might increase the ability of monocytes to control proliferation of M. tuberculosis, or cause monocytes to mature into cells able to respond appropriately to IFN-gamma. Incubation of monocytes with three cholecalciferol metabolites induced anti-tuberculosis activity to an extent that correlated with their binding affinities to the intracellular receptor protein for the derivatives. 1,25-(OH)2 D3 also primed monocytes for phorbol myristate acetate-triggered reduction of nitroblue tetrazolium. The effects were additive rather than synergistic with those of IFN-gamma. Monocytes incubated with IFN-gamma developed 25-OH D3 1-hydroxylase activity, detected by conversion of tritiated 25-(OH) D3 to a more polar metabolite which coeluted with 1,25-(OH)2 D3 on straight and reverse-phase HPLC. The latter is a more active form in vivo. These findings help to explain claims for the efficacy of vitamin D in the treatment of some forms of tuberculosis, and also the occasional finding of raised serum calcium, and disturbed vitamin D metabolism in these patients.

Cells, Cultured↗

PubMed1986

Responsiveness to live M. tuberculosis, and common antigens, of sonicate-stimulated T cell lines from normal donors.

Live mycobacteria are more efficient vaccines against mycobacterial disease than killed ones. A possible explanation is the existence of important protective antigens released by live bacilli, which are not present in any significant quantity in dead ones. Conversely, internal mycobacterial antigens may be irrelevant to protection if not released by live bacilli. We show here, using T cell lines derived by limiting dilution from the peripheral blood of normal donors stimulated with sonicated BCG, that a variable percentage of sonicate responsive T cells is unable to respond to live M. tuberculosis. The possibility that such lines have an immunopathological, rather than protective role, is discussed.

Antigens, Bacterial↗

PubMed1986

Activation of macrophages to inhibit proliferation of Mycobacterium tuberculosis: comparison of the effects of recombinant gamma-interferon on human monocytes and murine peritoneal macrophages.

When cultured in 20% heat-inactivated human serum, human monocytes from seven donors were not on average significantly different from non-activated murine peritoneal cells (cultured simultaneously and in an identical manner) in their ability to inhibit BCG and, when calculated relative to growth of bacilli in the same medium without macrophages, to enhance the growth of Mycobacterium tuberculosis. Recombinant gamma-interferon caused marked inhibition of virulent M. tuberculosis by murine (BALB/c) peritoneal macrophages. This effect was seen, whether the cells were cultured in 10% fetal calf serum or in 20% heat-inactivated normal human serum, with or without the addition of iron supplements. However, unlike murine cells, the addition of crude lymphokine or recombinant gamma-interferon to human monocytes caused only weak inhibition of M. tuberculosis, and in some instances, gamma-interferon caused enhancement of growth of the bacilli. Monocytes were only slightly more effective if precultured for 4-8 days before the addition of the activating stimulus. This relative failure to develop anti-mycobacterial mechanisms occurred in spite of the activation of the cells as shown by a massive increase in reduction of nitro-blue tetrazolium inducible by phorbol myristate acetate.

Animals↗

PubMed1986

Quantitative transcervical uterine cultures in asymptomatic women using an intrauterine contraceptive device.

Quantitative transcervical uterine cultures were obtained in 100 asymptomatic women using intrauterine contraceptive devices for varying periods. Twenty women using barrier forms of contraception served as controls. Cultures were obtained safely and satisfactorily without trauma to either the endocervix or endometrium. It was found that normal uterine sterility was significantly compromised in women using an intrauterine contraceptive device. The number of intrauterine organisms cultured was associated with neither the type of intrauterine contraceptive device (Cu-7, Lippes Loop, Saf-T-Coil) nor the duration of use (less than one month to greater than five years).

Adult↗

PubMed1985

A simple method for the solubilisation of reduced NBT, and its use as a colorimetric assay for activation of human macrophages by gamma-interferon.

We describe a simple method by which the insoluble blue formazan dye produced by the reduction of nitro blue tetrazolium can be dissolved without heating using potassium hydroxide and dimethyl sulphoxide. This modification enhances the sensitivity and increases the applications of tests performed using the microELISA method and removes variations caused by uneven cell monolayers. It also allows quantification of NBT reduced by cells adherent to coverslips or in larger wells or Petri dishes, and can be used as a sensitive assay for macrophage activation by gamma-interferon.

Animals↗

PubMed1985

The effect of lymphokines on the ability of macrophages to protect mycobacteria from a bactericidal antibiotic.

Murine peritoneal macrophages protect Mycobacterium intracellular from amoxycillin added to the culture medium. This protective effect is enhanced by the addition of macrophage-activating lymphokines, although in the absence of amoxycillin these lymphokines cause macrophage-mediated inhibition of the organisms. Thus about 10 times more organisms survive exposure to 100 microgram/ml of amoxycillin for 3 days in the presence of lymphokine-activated macrophages than in their absence, whereas without amoxycillin the reverse is true. These findings suggest that in this in vitro system lymphokines cause stasis rather than kill of the organisms. The possibility that lymphokine-induced bacteriostasis protects mycobacteria from antibiotics in vivo is discussed.

Amoxicillin↗

PubMed1985

Incidence and prevalence of Down's syndrome--a discussion and report.

This paper seeks to demonstrate that a slow but steady rise in the Down's syndrome population can be expected. Studies concerned with Down's populations have been critically examined along with factors effecting such populations; i.e. better health care, changes in maternal child-bearing age, under-diagnosis and prenatal diagnosis. It is suggested that better health care and a reduction in under-diagnosis could create a recognized increase in the Down's syndrome population, but that the effect of changes in child-bearing age is questionable. The effect of prenatal diagnosis is less than might be anticipated and changes in public attitudes could reduce this effect even further. In view of conflicting data from many of the studies examined, a small investigation was carried out in the Sheffield and Buckinghamshire areas. Results from these surveys indicate a current overall incidence rate of 4.63 per 10 000 though there are differences between the two areas.

Adolescent↗

PubMed1985

I-A restricted activation by T cell lines of anti-tuberculosis activity in murine macrophages.

Tuberculosis and leprosy remain two of the world's most significant diseases. Immunity involves the activation of macrophages by lymphokines but the details are unknown because there has been no objective assay for the relevant effector function using human pathogens. We previously reported the use of tritiated-uracil uptake by surviving mycobacteria as a measure of the anti-mycobacterial effect of human monocytes. We describe here the use of a modification of this assay to measure control of the proliferation of Mycobacterium tuberculosis in murine peritoneal macrophages. A bacteriostatic effect can be induced in macrophages infected with M. tuberculosis, by adding small numbers of Ly 1 +2- T cells from in vitro lines derived from immunized mice. The phenomenon is dependent on compatibility at the I-A locus of the major histocompatibility complex (MHC) and mediated by soluble factors. Such T cells also recognise and activate macrophages infected with other mycobacterial pathogens. Thus, T cells recognising shared mycobacterial antigens are active. The findings have implications for MHC linked susceptibility to mycobacterioses and the hypothesized ability of cross-reactive environmental mycobacteria to abrogate or pre-empt the protective efficacy of subsequent BCG vaccination.

Animals↗

PubMed1983

Intravenous metronidazole in the newborn.

Twenty four neonates at high risk of anaerobic sepsis were treated with intravenous metronidazole, 7.5 mg/kg, 8 hourly, for a mean period of 5 days. The highest observed concentration after the first dose (mean +/- SD) 9.6 +/- 4.0 mg/l (56.1 +/- 23.4 mumol/l) was significantly lower (P less than 0.001) than the highest observed concentration after the final dose (mean +/- SD) 19.3 +/- 8.6 mg/l (112.7 +/- 50.2 mumol/l). The overall metronidazole half life was (mean +/- SD) 23.4 +/- 13.1 hours. The half life after the first dose (mean +/- SD) 21.9 +/- 10.1 hours was not appreciably different from the half life after the final dose (mean +/- SD) 21.6 +/- 12.4 hours. The concentrations of the major metabolite of metronidazole (20396RP) also rose appreciably during treatment. No side effects of metronidazole were noted and its extended half life in neonates suggests that less frequent dosage would be appropriate.

Bacterial Infections↗

PubMed1979