Biomedical subjects
Publications and source records attributed to M Tremblay.
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"Methods based on survival probabilities are often used for estimating net migration by age over a given period, and the bias introduced by these methods [has] been discussed by many authors. This note shows that the results obtained in this respect by Wunsch and Termote (and used by Courgeau as well) under the hypothesis of an even distribution of migrants over the period, are actually valid for another assumption." (SUMMARY IN ENG AND SPA)
We have succeeded in infecting human thymic lymphocytes with both the HIV-IIIB laboratory strain of HIV-1 as well as with a clinical isolate of this virus. Thymic lymphocytes were at least as susceptible to infection by HIV-1 as were cord blood lymphocytes, but appeared to display somewhat greater resistance to the cytopathic effects of the virus. As measured variously by each of indirect immunofluorescence for detection of viral p17, antigen capture assay for the presence of viral p24 in culture fluids, and levels of viral reverse transcriptase activity in culture fluids, infection of thymic lymphocytes could be detected as early as 2 days after infection by HIV-1, and persisted through at least 14 days of tissue culture maintenance. These findings suggest that thymic lymphocytes may be susceptible to infection by HIV-1 in vivo, and may also be relevant to our understanding of HIV-1-induced pathogenesis, particularly in pediatric populations.
We have examined 3 different EBV-carrying B cell lines, in terms of ability to be super-infected by the human immunodeficiency virus (HIV-1), and have followed these lines, after infection by HIV-1, over a period of 3 months. We found significant variation among different HIV-1 strains in terms of the multiplicity of infection required to initiate infection in these EBV-positive cell lines. Persistent infection by HIV-1 in the absence of detectable cytopathic effects could be demonstrated, as evaluated by a variety of techniques, including reverse transcriptase assay and immunofluorescence. The results indicate also that all of these cell lines produced progeny HIV-1 intermittently, with large amounts of virus production on some days but not others. In contrast, they were all able to continuously express p24.
Infection of a newly described human T lymphoid cell line, CEM-CL10, with three different variants of HIV-1 resulted in cytopathic effects followed by cell lysis. Following primary lytic infection, proviral DNA could not be detected by Southern blot analysis in the outgrowth of the surviving CEM-CL 10 cells 60 days after initial exposure to HIV-1. These surviving cells could be further grown as a separate line, derived from CEM-CL10, and were found to be resistant to subsequent infection by HIV-1. A marked decrease in CD4 antigen expression was observed in these latter cells but not of the CD3 and transferrin receptor antigens. This decline in cell surface CD4 expression was correlated with both an absence of specific CD4 mRNA and with changes in structure of the CD4 gene. Both the HIV-1-sensitive CEM-CL10 cell line and its CD4(-), HIV-1-resistant derivative line, will be made available to interested investigators.
Patients with acquired immunodeficiency syndrome (AIDS) commonly suffer from opportunistic infections associated with members of the herpes virus family. To investigate whether certain of these other viruses might have an effect on the ability of the human immunodeficiency virus type 1 (HIV-1) to replicate, we coincubated peripheral blood mononuclear cells (PBMC) from nine HIV-1-seropositive donors with live preparations of various herpes viruses. In seven of nine cases, exposure of PBMC to preparations of either HSV-1, HSV-2, or CMV stimulated the cells to become active producers of HIV-1, as determined by reverse transcriptase activity and by the presence of infectious progeny virus. This increased production of HIV-1 particles appeared to be a consequence of mitogenic proliferation and of herpes virus-encoded transacting factors. These results supplement earlier findings on the molecular activation of the HIV-1 genome by both HSV and CMV genetic elements and point to a possible role for these viruses in the pathogenesis and ultimate clinical outcome of HIV-1 infections.
It is known that speed and accuracy in recognizing words are constrained by their frequency of occurrence ("frequency effect"). This study bears on the diachrony of the word frequency effect. Our postulates in this respect were (1) that a significant frequency effect should be present throughout adulthood, irrespective of age, and (2) that the magnitude of this effect should be greater among the elderly. Twenty young and 20 older healthy adults were submitted to a lexical decision experiment. Results confirmed our first postulate but invalidated the second one, that is, significant frequency effects were found in both groups but these effects were documented to be of identical magnitude. An attempt is made at explaining the latter result from a theoretical standpoint. The former is interpreted as further evidence that senescence (normal aging) does not interfere with passive, automatic and unconscious mental processes. Moreover, it is suggested that--if observed among otherwise apparently healthy elderly adults--modifications of the frequency effect might be taken as a cognitive marker of disease.
How 3'-azido-3'-deoxythymidine (AZT) affects the ability of three different variants of HIV-1 to infect a line of EBV-transformed B cells was studied. Susceptible cells were pretreated with three different concentrations of AZT (1, 5, and 10 microM) for 4 h before viral inoculation and were maintained after infection in drug-containing medium. Establishment of viral infection was assessed by indirect immunofluorescence for viral antigens and by antigen capture assay carried out on culture fluids. AZT completely blocked infection in one of the HIV-1 variants studied; in the other two, treatment of cells with AZT significantly delayed the appearance of progeny virus.
We determined whether drug-resistant variants of HIV-1 could be isolated from the peripheral blood mononuclear cells of 20 individuals with HIV infection (Centers for Disease Control groups II and III) on long-term zidovudine (AZT) therapy. Toward this end, zidovudine (10 microM) has been included in the tissue culture medium used to isolate HIV-1. Under these circumstances, virus with a zidovudine-resistant phenotype was successfully obtained in five out of 20 cases. This property of drug resistance appeared to be stable, and did not disappear upon extended replication of such virus in the absence of drug pressure. Drug-resistant virus could also be isolated from these subjects on subsequent occasions, but was not present in samples obtained prior to therapy. Replication of these zidovudine-resistant isolates in tissue culture was inhibited by each of four other nucleoside analogues. Thus, other drugs may be useful in controlling selective zidovudine-resistant variants of HIV-1.
Using standard tissue culture techniques we cultured cells from 12 large choroidal melanomas to assess the capacity of pre-enucleation radiotherapy to decrease the viability of melanoma cells. Specimens from the six melanomas that received 40 Gy given in 20 daily fractions did not grow in tissue culture. Specimens from the six nonirradiated tumours did grow, with a mean in-vitro doubling time of 39.6 hours. The results show that the applied regimen of pre-enucleation radiotherapy decreased the viability of choroidal melanoma cells. Further study is needed to determine the correlation between the in-vitro characteristics of irradiated and nonirradiated choroidal melanomas.
When the patient's pleural space is filled with fluid, palliative treatment measures--thoracic drainage and pleurodesis--and diligent nursing care can help her breathe easier.
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Nuclear proteins were extracted from purified nuclei of human primary breast tumors (BrT) and bladder tumors and of human normal breast, kidney and lymphocytes by enzymatic treatment. SDS-Polyacrylamide gel electrophoresis of nuclear proteins from breast tumors showed different bands in the molecular weight zones from 25 to 220 kDa which were absent or present only as traces in normal breast tissue. Murine monoclonal antibodies (MAbs) have been produced using nuclear extracts of human primary breast tumors as immunogens. Approximately 2,000 hybridomas were generated from 5 hybridizations. According to their reactivity to BrT nuclear extracts and mammary carcinoma cell line MCF-7, seven hybridomas were selected and cloned. They were further characterized with histological immunoperoxidase assays of formaldehyde-fixed BrT paraffin tissue sections. MAb 6A3 particularly gave strong nuclear staining with all BrT specimens while MAb 1D8 showed both nuclear and cytoplasmic staining with only some of them. Specimens from mammoplasty did not react with these MAbs. Immunoblotting of BrT nuclear extracts as developed with MAbs 6A3 and 1D8 revealed major protein bands with molecular weight of 120 and 130 kDa. The potential use of these MAb-defined BrT-related nuclear proteins as markers for human breast cancer was suggested.
The first well documented case of acute pyogenic vertebral osteomyelitis presenting as the initial manifestation of Streptococcus sanguis endocarditis is reported. The importance of suspecting vertebral osteomyelitis in the presence of disc infection and the diagnostic value of imaging procedures are underlined.
Over a period of six months, we have followed a total of six different EBV-transformed B cell lines, each of which has been infected by the human immunodeficiency virus (HIV-1). The results indicate that all of these lines were initially able to produce progeny HIV-1, but that over time three of them ceased to produce infectious virus and two lines failed to elaborate significant levels of reverse transcriptase activity into the medium. We further found that two of the latter cell lines continued to express the viral antigens p17, p24 and/or gp41, as determined by indirect immunofluorescence assay, at times after progeny HIV-1 could no longer be detected. Those cell lines which continued to secrete progeny HIV-1 did so intermittently with large amounts of virus production on some days but not others. We further found that treatment of such cells with 3' azido-3'-deoxythymidine (AZT) completely inhibited production of progeny HIV-1.
The effect of cyclosporine A (CyA) on the ability of the human immunodeficiency virus type 1 (HIV-1) to infect the H-9 T-cell leukemic line, as well as interleukin-2 (IL-2)-grown human peripheral blood-derived lymphocytes, has been studied. Pretreatment of H-9 cells and human lymphocytes with CyA over 24 hours completely prevented viral infection over a 21-day period, whereas the addition of drug at two hours postinfection with HIV-1 had a significant inhibitory effect on viral replication and expression of the virus-specific antigens p17 and p24. However, if CyA was added at later times to these lymphocytic cells, this inhibitory effect was lost. Indeed, the removal of CyA from cultures that had been treated from two hours after infection led to the rapid production of progeny virus. HIV-1 was able to infect peripheral blood lymphocytes obtained from each of four kidney allograft recipients on long-term CyA antirejection therapy, as long as drug was not included in the culture medium. In addition, we asked what effect pretreatment with CyA of cells of the U-937 monocytic line and primary cultures of human monocytes/macrophages might have on infection by HIV-1. CyA had no demonstrable effect on the ability of HIV-1 to infect cells of either type.
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Several poliovirus and coxsackievirus isolates from environmental sources were compared with laboratory strains to determine their rate of inactivation by chlorine. All viruses were tested for up to 1,000 min in the presence of an initial free residual chlorine level of ca. 0.4 mg/liter. Coxsackievirus B5 (CB-5) isolates were found to be more resistant to chlorine than coxsackievirus B4 (CB-4), followed by poliovirus 1, 2, and 3 in order of decreasing resistance to chlorine. Environmental isolates of CB-5 were more resistant than the laboratory strain tested, and for two strains 12 and 22% of the input virus was still infectious after 100 min in the presence of free residual chlorine. Although CB-4 isolates were less resistant to chlorine than CB-5 isolates, after 1,000 min of contact 0.01% of the input virus was still infectious. Except for CB-5 isolates, isolates from environmental sources did not appear to be more resistant to chlorine than laboratory strains. Viruses isolated at different phases during the preparation of drinking water were not more resistant to chlorine and must thus have been protected by other mechanisms.