Gas chromatographic assay of cellular fatty acids and alcohols for the identification of Mycobacterium species

Ten mycobacterial species obtained from 141 cultures isolated from clinical specimens were studied. The cultures were grown on solid medium and then analysed-after saponification, methylation, extraction with organic solvent and washing of the organic phase--by capillary gas-liquid chromatography for fatty acid and secondary alcohol composition. The absence of secondary alcohols was characteristic of M. genavense, M. tuberculosis and the following Mycobacterium species with specific branched-chain fatty acids allowing their direct identification: M. gordonae, M. kansasii and M. marinum. The presence of secondary alcohols was characteristic of M. avium, M. phlei, M. scrofulaceum, M. terrae and M. xenopi. In the case of M. xenopi direct identification was made possible by the presence of a specific alcohol.

Complete in vitro prosthesis endothelialization induced by artificial extracellular matrix

This report presents our research on the conditions necessary to substain optimal in vitro prosthetic endothelialization using human endothelium cultures. Human vein endothelial cells were seeded at a concentration of 3 x 10(5)/cm2 in a gelatinized Dacron patch graft coated with a commercial collagen film, using a solution of fibrin glue. Endothelium adhesion, proliferation, and survival were measured by [3H]thymidine incorporation, after 7 days of incubation. Finally, the morphology of prosthetic endothelialization was analyzed by scanning electron microscopy. We observed that the Dacron patch grafts coated with collagen film were able to promote endothelialization better than the prostheses coated with highly concentrated collagen solution or gelatin. We therefore concluded that the collagen film that supports endothelial cell adhesion and proliferation uniformly covers the entire synthetic endoluminal surface of the Dacron graft, thus preventing endothelial cell alterations induced by direct contact with the synthetic prosthetic surface.

Development of horse polyclonal antiserum inhibiting all in vitro biological functions of human IFN-gamma

Following a standard immunization protocol with recombinant human interferon-gamma (IFN-gamma), a horse polyclonal antiserum was obtained and evaluated for its ability to interfere with multiple IFN-gamma activities in vitro. Data obtained show that polyclonal horse antiserum neutralizes the antiproliferative activity of IFN-gamma, inhibits the binding of IFN-gamma to cellular receptors, and can up-regulate HLA-DR antigen expression and interfere with its antiviral activity. The broad neutralizing capacity of horse polyclonal antiserum has been assessed on cell lines which differ as to origin and sensitivity to IFN-gamma. Moreover, we observed that this antiserum could inhibit the binding of radiolabeled IFN-gamma to its cellular receptor, its subsequent internalization into the target cell, and its antiviral activity. As it is able to inhibit all the biological activities of IFN-gamma, this antiserum might provide new therapeutic approaches to diseases with evidence of activated cell-mediated immunity.

Isolation and chemoantibiotic resistance of Ureaplasma urealyticum in HIV-1 infected patients

The presence of Ureaplasma urealyticum was evaluated on 1912 vaginal and urethral swabs from HIV-1 seronegative (HIV-) inpatients (210) and outpatients (503) suffering from acute urethritis or vaginitis; asymptomatic HIV- outpatients (201); and asymptomatic HIV-1 seropositive (HIV+) inpatients (120). The study reported an increased frequency of Ureaplasma urealyticum isolates in asymptomatic HIV+ compared to asymptomatic HIV- subjects. As expected, the frequency of Ureaplasma urealyticum isolates increased in symptomatic HIV- subjects. Strains of Ureaplasma urealyticum resistant to ciprofloxacin, tetracycline and minocycline were more frequently isolated in HIV+ (34.1%) than HIV- (3.8%) subjects; on the other hand, only 1 out of 704 (0.1%) strains isolated from outpatients was resistant to ciprofloxacin. We found no association in HIV+ patients between Ureaplasma urealyticum infection and CD4 count or HIV-1 p24 antigenemia.

HIV p17 enhances lymphocyte proliferation and HIV-1 replication after binding to a human serum factor

OBJECTIVE

To analyse the role of recombinant HIV-1 protein p17 in the modulation of cell activity.

METHODS

Peripheral blood mononuclear cells (PBMC) obtained from healthy donors were cultured in the presence or absence of p17 with mitogens such as phytohaemagglutinin or interleukin-2 and their response assayed by cell proliferation. Cross-linking experiments were employed to investigate the presence of a binding between p17 and factor(s) present in human serum. An immunoenzymatic assay for p24 antigen detection was used to analyse the effect of the addition of exogenous p17 to cultures of PBMC infected with HIV-1 in vitro.

RESULTS

Purified recombinant p17 protein at a concentration of 0.25 microg/ml significantly increased the proliferation of preactivated PBMC obtained from healthy donors. This effect was obtained by binding p17 to factor(s) present in human serum and observed on both CD4+ and CD8+ T cells. Recombinant p17 also induced an increased rate of HIV-1 replication, probably due to enhanced T-cell proliferation. The activity of p17 protein was inhibited by anti-p17 antibodies generated by injecting recombinant p17 in rabbits, but not by human antibodies generated during the natural course of HIV infection.

CONCLUSION

Characterization of the human factor(s) and identification of the interacting p17 epitope(s) will improve our understanding of the mechanisms used by HIV to efficiently replicate in our organisms.

Lack of polarized type 1 or type 2 cytokine profile in asymptomatic HIV-1-infected patients during a two-year bimonthly follow-up

The production of type 1 (interferon or IFN-gamma) and type 2 (interleukin or IL-4 and IL-10) cytokines by mitogen-stimulated peripheral blood mononuclear cells (PBMCs) obtained from asymptomatic human immunodeficiency virus-seropositive (HIV+) patients untreated with any antiviral, antibacterial or antimycotic drugs, and from healthy individuals, was evaluated by quantitative ELISA. Patients who were HIV+ were characterized by the absence of abnormal cytokine production. The level of each cytokine differed among individuals in the same group with intersubject variations greater for HIV+ patients than for healthy individuals. The longitudinal evaluation of IFN-gamma, IL-4 and IL-10 production showed intrasubject variations which were particularly marked in HIV+ patients. Accordingly, HIV+ patients and, to a lesser extent, healthy individuals were characterized by a wide spectrum of possible profiles, which were confined to type 0 phenotype. In HIV+ patients no correlation was found between each cytokine level and the number of CD4+ T cells, not even in those with a falling CD4+ T-cell count and clinical symptoms.

Contribution of CD4+, CD8+CD28+, and CD8+CD28- T cells to CD3+ lymphocyte homeostasis during the natural course of HIV-1 infection

The relationship between the number of circulating CD4+ T cells and the presence of particular CD8+ T cell subsets was analyzed by flow cytometry on PBL from asymptomatic HIV-1-infected patients whose specimens were collected every 2 mo for a total period of 32 mo. Only slight variations were detected in the absolute number of lymphocytes and percentage of CD3+ lymphocytes, whereas both CD4+ and CD8+ T cell subsets showed wide intrapatient variation. Variations in the number of CD8+CD28+ cells paralleled those of the CD4+ T cell subset in each patient tested, while the presence of CD8+CD28- T cells correlated inversely with CD4+ and CD8+CD28+ T cells. These data show that changes in the number of circulating CD4+-and CD8+CD28+ T cells are strongly related to the presence of CD8+CD28- T cells in these patients. Insight into the significance of CD8+CD28- T cell expansion will allow us to understand the mechanisms and significance of the HIV-1- driven change in CD4+CD8+ T cell homeostasis and the basic immunopathology of HIV disease.

Isolation of HTLV-1 from an aggressive form of ATL in a Romanian patient not at risk of infection and with seronegative family members

We present the clinical, virological and haematochemical data of a 22 year old patient from Romania with Adult T Cell Leukaemia (ATL). Viral isolation in peripheral mononuclear blood cells (PMBC), detection of DNA sequences of HTLV-1 by Polymerase Chain Reaction (PCR) and of antibodies by Elisa and Western blot were performed. The patient does not belong to any risk group and additionally all members of her family are seronegative for HTLV-1, the aetiological agent of ATL. The role of viral infection remains open.

T cells from individuals in advanced stages of HIV-1 infection do not proliferate but express activation antigens in response to HIV-1-specific antigens

Like T cells from healthy subjects, those of HIV-1-infected patients are capable of expressing activation antigens on their surface after antigenic or mitogenic stimulation, but their proliferative activity is strongly reduced or even absent, especially in patients with advanced stages of the disease. The characteristic of expressing activation antigens in response to different stimuli in the absence of cell proliferation is shared by CD4+ and CD8+ T-cell subsets from HIV-1-infected patients. The number of T cells capable of expressing CD25 and CD71 in response to HIV-1-related antigens but not of proliferating increased significantly with the progression of the disease, but the number of T cells capable of expressing the two activation antigens in response to the classic tetanus toxoid recall antigen decreased. The higher numbers of T cells capable of responding to HIV-1-related antigens in conjunction with a reduction in the number of T cells responding to recall antigens may explain the occurrence of different infections, including opportunistic microorganisms, during the more advanced stages of HIV-1 infection. Because the increase in the number of HIV-1 antigen-responding T cells (defined by CD25 and CD71 activation antigen expression) is a characteristic of symptomatic HIV-1-infected patients, expression (by flow cytometry) of these activation antigens on T cells in response to HIV-1 antigens could be used as a new marker of disease progression.

In-vitro study of the synergy between beta-lactam antibiotics and glycopeptides against enterococci

The synergy between glycopeptides and beta-lactams was studied using different techniques such as broth macrodilution, killing curves and agar dilution combined with agar diffusion. Two glycopeptide-resistant enterococci isolated from different clinical samples were used. Results showed different effects with significant changes in MICs. Antibacterial activity was related to the concentration of glycopeptide and beta-lactam for Enterococcus faecalis 8253, while for Enterococcus faecium 8072 a paradoxical effect was observed. With this strain, the best synergic effect was detected at teicoplanin concentrations of 1-4 mg/L, but antibacterial activity was reduced at concentrations of 8, 16 and 32 mg/L. No synergic effect was observed with vancomycin. The combination of agar dilution with agar diffusion techniques may constitute a simple method for routine detection of synergic effects between glycopeptides and beta-lactams.

Flow cytometric analysis of activation markers on stimulated T cells and their correlation with cell proliferation

The expression of activation antigens, namely CD25, CD69, CD71, and HLA-DR on T cells from 15 healthy individuals stimulated with different mitogens and specific antigens was evaluated by immunofluorescence assay and flow cytometric analysis and compared with cell proliferation as a function of [3H]thymidine incorporation. CD69 was the earliest expressed antigen on stimulated cells, while HLA-DR was the latest. Regardless of the stimulus used, lymphocytes expressing CD25 and CD71 were always more numerous than cells expressing CD69 and HLA-DR. Variations in the proportion of CD4+ and CD8+ T cells expressing each activation marker were observed with different antigenic stimuli. The expression of each activation marker showed overall agreement with the [3H]thymidine incorporation assay in discriminating between positive and negative immune response. However, no correlation was observed between the percentage of CD25-, CD69-, CD71-, and HLA-DR-positive T cells and the amount of [3H]thymidine incorporation. Moreover, low doses of mitogens and antigens as well as short time of stimulation were sufficient to induce T cells to express activation antigens but not to proliferate. Our data show that results obtained by flow cytometry and [3H]thymidine incorporation may differ qualitatively, at least under certain conditions; this suggests that the 2 assays are complementary, and when combined, may gives a clearer understanding of events leading to efficient cell-mediated immune response.

Natural antibodies to interferon-gamma

Natural antibodies to interferon (IFN)-gamma were detected in the serum of virus-infected patients and also, at a low titre, in the serum of healthy subjects. The increased titre of antibodies to IFN-gamma in the sera of virus-infected patients, and its decrease with clinical resolution, indicate that these antibodies are related to viral infection and probably reflect IFN-gamma production as a result of antigenic stimulation in vivo. Natural antibodies to IFN-gamma were affinity purified and studied for their capability to interfere in vitro with the multiple activities of the lymphokine. Data obtained show that these human anti-IFN-gamma antibodies have no inhibitory effect on the antiviral and antiproliferative activity of IFN-gamma and do not interfere with the binding of the lymphokine to its specific cell receptor. Instead, they can inhibit the expression of HLA-DR antigens induced by IFN-gamma on U937 cells and interfere, in mixed lymphocyte culture, with the proliferation of lymphocytes and the generation of cytotoxic lymphocytes. Experiments in animal models suggest that natural antibodies to IFN-gamma may have a role in the immunoregulatory process limiting the intensity and/or duration of immune response. As they can interfere only with the immunomodulating activities of IFN-gamma, these antibodies might open up new therapeutic approaches to diseases with evidence of activated cell-mediated immunity.

Heat-killed Bacillus subtilis inhibits T-cell proliferative response to mitogens and recall antigens

Heat-killed vegetative forms of Bacillus subtilis were found to impair considerably the capacity of human T-lymphocytes to secrete interleukin-2 (IL-2) and to proliferate (in terms of [3H]thymidine incorporation) after phytohaemagglutinin (PHA) stimulation. B. subtilis was also found to interfere with T-cell proliferation induced by concanavalin A (Con A) and the recall antigen tetanus toxoid (TT). The suppressive activity was dependent on bacterial concentration, and was not ascribed to mitogen, medium-nutrient absorption or cell killing. Moreover, B. subtilis did not interfere with mitogen-induced IL-2 receptor expression on the T-cell surface. On the other hand, B. subtilis did not interfere with T-cell proliferation induced by phorbol myristate acetate (PMA) and ionomycin stimulation. All data obtained suggest the binding of B. subtilis subcomponents to- or very close to-the T-cell receptor (TCR). Identification and purification of the basic structure(s) or component(s) of B. subtilis with TCR antagonist activity in vitro will help to exploit different aspects of T-cell activity and development, and possibly, will provide a means of specific control or modification of the immune response.

Interferences of urinary tract infection in the measurement of urinary nitrous oxide

OBJECTIVES

To investigate the effective role of micro-organisms in producing N2O.

METHODS

The N2O in either urine samples inoculated with 24 microbial strains or urine samples from patients with urinary tract infections were measured.

RESULTS

Gram negative bacilli generally produced high amounts of nitrous oxide (N2O), whereas Gram positive cocci and yeasts did not. The production of N2O depends on the incubation time and follows exponential kinetics, reaching a plateau at 48 hours. Furthermore, the results of urinocultures agreed well with N2O concentrations found in urine samples: samples negative for bacteria were found to contain very low concentrations of N2O whereas those positive--for example, for Enterobacteriaceae--gave highest N2O values.

CONCLUSION

The urinary tract infections caused by Gram negative bacilli are important confounding factors in biological monitoring practices of exposure to inhalation anaesthetics. The current methods adopted to avoid these factors (urine acidification, storage of samples at 4 degrees C) are not good enough because of the relative acid tolerance of some strains and the production of N2O directly into the bladder.

Detection of Mycoplasma genitalium from urethral swabs of human immunodeficiency virus-infected patients

Mycoplasma have been suggested as co-factors in the pathogenesis of acquired immune deficiency syndrome (AIDS). The prevalence of urethral infection by Mycoplasma genitalium was determined by polymerase chain reaction (PCR) with urethral swabs from 35 HIV-infected patients at different stages of the disease (all of them were heterosexual men). M genitalium was detected in 2 out of 19 non-AIDS (stage A and B) patients and in a similar proportion (1 out of 14; 7.1%) of samples from healthy individuals. A dramatic increase in the frequency of M. genitalium detection was observed in samples of AIDS (stage C) patients. In fact, 9 out of 16 (56.2%) specimens tested positive by PCR. We found no association in AIDS patients between M. genitalium infection and CD4 count, Human Immunodeficiency Virus (HIV) p24 antigenemia or opportunistic infection.

Detection and identification of Mycobacterium avium in the blood of AIDS patients by the polymerase chain reaction

One hundred fifty-three blood samples from patients positive for the human immunodeficiency virus (HIV) were analyzed by polymerase chain reaction (PCR) to detect the presence of Mycobacterium avium. Samples were collected from patients who also had blood cultures performed by a radiometric method. Blood samples were centrifuged on a Ficoll-Hypaque gradient to purify peripheral blood mononuclear cells. The purified cells were washed and incubated with a resin, boiled to release mycobacterial DNA, and then amplified. Polymerase chain reaction products were detected by a nonisotopic method. A 123 base-pair (bp) insertion sequence, namely IS6110, from Mycobacterium tuberculosis complex was also included in the reaction as an internal control of Taq polymerase activity to exclude the presence of enzyme inhibitors. This IS6110 fragment can be distinguished from the 383 bp target product on ethidium bromide-stained agarose gel and may also be used in a colorimetric assay. Such results were compared with the results of culture and indicated that the assay is as sensitive as bacteriological methods, though faster.

Characterization of T cell subsets involved in the production of IFN-gamma in asymptomatic HIV-infected patients

Cells capable of interferon (IFN)-gamma synthesis following mitogenic stimulation can be detected and quantified by a recently developed immunofluorescence assay and flow cytometric analysis. The production of IFN-gamma was investigated in a cohort of 20 asymptomatic human immunodeficiency virus (HIV)-seropositive patients with normal numbers of CD4+ lymphocytes, and in 10 healthy subjects. About 60% of asymptomatic stage A1 patients had increased percentages of blood lymphocytes capable of IFN-gamma synthesis, as compared to healthy subjects. The difference reflected the relatively higher numbers of CD8+ cells, in particular the CD8+ T cell subset lacking CD28 antigen expression. The strong correlation between the CD4+/CD8+ ratio and the CD8+CD28+/CD8+CD28- ratio suggests either a role for CD4+ cells in controlling the CD28+ phenotype or a role for CD8+CD28- cells in the decline of CD4+ lymphocytes. The peculiar ability of CD8+CD28- cells to produce high amounts of IFN-gamma, as compared to CD8+CD28+ cells, supports the hypothesis that the CD8+CD28- lymphocytes constitute a population that is functionally distinct from their double-positive counterparts.

IFN-gamma restores HIV- and non-HIV-specific cell mediated immune response in vitro and its activity is neutralized by antibodies from patients with AIDS

The addition of IFN-gamma to cultures of peripheral blood mononuclear cells (PBMCs) obtained from asymptomatic HIV-infected patients increased cell proliferation in response to HIV envelope synthetic peptides (Env), influenza A virus (VIRUS), and allogeneic lymphocytes (ALLO) but not to phytohaemagglutinin (PHA) stimulation. F(Ab)2 fragments of IgG purified from the sera of HIV-seropositive patients specifically interfered with IFN-gamma-induced cell proliferation in response to recall antigens. Neutralization of the lymphokine activity was found to be sustained by specific IFN-gamma antibodies. Data obtained demonstrate that IFN-gamma can restore the cell-mediated immunity of a number of asymptomatic HIV+ individuals in vitro, while IFN-gamma antibodies present in sera of patients with AIDS interfere with the activity of the lymphokine.

CD4+ and CD8+ lymphocytes of patients with AIDS synthesize increased amounts of interferon-gamma

Individual cells capable of interferon-gamma (IFN-gamma) synthesis are easily detected by immunofluorescence and flow cytometric analysis using an anti-IFN-gamma monoclonal antibody as specific reagent. By IFN-gamma flow cytometry assay, we demonstrated that HIV-seropositive patients, starting at the early stage of viral infection, generally have an increased percentage of lymphocytes potentially able to produce IFN-gamma, compared with healthy blood donors. IFN-gamma expression in patient lymphocytes was observed to increase with the progressive stages of HIV infection, with the highest figures occurring in stage C patients. Such increased IFN-gamma expression involved both CD4+ and CD8+ T cell subsets. Most interestingly, we found patients at the same stage of HIV infection who had similar numbers of total and CD4+ lymphocytes but highly different percentages of lymphocytes potentially capable of producing IFN-gamma.

Effect of galanin on growth hormone (GH) response to thyrotropin releasing hormone of rat pituitary GH-secreting adenomatous cells (GH1) in culture

The growth hormone (GH) releasing effect of thyrotropin-releasing hormone (TRH) and galanin, a 29-amino acid peptide widely distributed in mammalian CNS, alone or in combination was investigated in cultured rat pituitary tumor cells (GH1). TRH stimulated GH secretion in GH1 cells (maximal stimulation at the dose of 0.1 microM). Galanin alone had a significant GH inhibitory effect in GH1 cells at all the doses used. When the two peptides were administered in combination, no significant changes as compared to baseline levels were observed. The results of this study indicate that galanin has potent direct inhibitory effects on baseline and TRH-stimulated GH release from rat tumor cells.

Monoclonal antibodies against antigens exposed on the surface of vegetative forms and spores of Myxococcus virescens

Twelve monoclonal antibodies (mAbs) directed against cell-surface antigens of Myxococcus virescens cells were developed and partially characterized. All of them recognized multiple, diffuse proteic bands in Western blot and four were also reactive to living bacteria, as assessed by flow cytometry. The four latter mAbs recognized antigens common to a number of vegetative forms and spores. The selective expression of proteins recognized by mAbs on the microorganisms and the possible applications of mAbs to the study of myxobacterial cell interaction are discussed.

Purification of LamB proteins using continuous elution electrophoresis: a comparison with immunoaffinity chromatography

LamB is a membrane protein that allows the exposition of a foreign peptide on the surface of a recombinant E. coli cells. An immunopurified hybrid LamB protein has been used to elicit high-titre antibodies to a foreign epitope. Looking for a simpler purification procedure we have compared the traditional approach, which includes affinity chromatography, to continuous elution electrophoresis, in the purification of two different hybrid LamB proteins as foreign epitopes. The results obtained showed that both methods yielded the same purification, although the electrophoretic procedure had a higher yield. Continuous-elution electrophoresis could be a useful tool for the purification of membrane proteins.

A monoclonal antibody to the NH2-terminal region of human interferon-gamma inhibits its antiproliferative activity without affecting its internalization

MAb IGMB-15, an anti-hIFN-gamma MAb, neutralizes the antiproliferative activity of hIFN-gamma without affecting that of hIFN-alpha or hIFN-beta. The neutralizing capacity of MAb IGMB-15 is wide: it has been assessed on cell lines whose origin and sensitivity to hIFN-gamma differ. The binding of hIFN-gamma to its receptor and its subsequent internalization into the target cell were not influenced by the antibody. MAb IGMB-15 has been found to interact with hIFN-gamma in solution but not when the lymphokine was associated with its cell surface receptor, showing that the growth of certain cell lines can be inhibited at the cell membrane level. This finding is consistent with the existence of an accessory factor responsible for the antiproliferative activity of hIFN-gamma.