PubMed Health⌕ Search

Biomedical subjects

K Numazaki

Publications and source records attributed to K Numazaki.

At least 73 records · Page 4Linked to original sources
PubMed1990

Resistance to infection by HIV-1 of peripheral blood mononuclear cells from HIV-1-infected patients is probably mediated by neutralizing antibodies.

We have investigated whether PBMC of HIV-1-seropositive subjects are as susceptible to in vitro infection by HIV-1 as are PBMC from seronegative controls. Accordingly, stimulated PBMC from 19 HIV-1-infected subjects were inoculated with four different variants of HIV-1. None of these cultures produced either detectable quantities of viral reverse transcriptase activity or p24 Ag following inoculation with HIV-1. In contrast, in five of six cases in which these PBMC were depleted of B cells by antibody plus complement prior to viral inoculation, the presence of viral reverse transcriptase and p24 Ag was detected. The presence of normal levels of CD4-Ag at the surface of the CD4+ cells in these populations was established by flow cytometry. Analysis by an immunoblot assay revealed that anti-HIV antibodies were present in the sera obtained from these infected donors; in addition, 7 of 10 culture fluids derived from the nondepleted PBMC were shown to contain virus-neutralizing antibodies. Cultures which were depleted of B cells did not contain detectable levels of antiviral antibodies. Confirmation that the virus produced by the PBMC which had been depleted of B cells was of the strain used to infect the cultures, rather than that which initially caused patient infection, was provided on the basis of differential susceptibility to antibody neutralization. These results suggest that antibodies produced by B cells in cultures of PBMC from seropositive donors may restrict infection by HIV-1 of such cultures under laboratory conditions.

Adult↗
PubMed1990

Infection of human thymic lymphocytes by HIV-1.

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.

Cells, Cultured↗
PubMed1989

Chlamydia trachomatis infections in infants.

In recent years considerable progress has been made in understanding chlamydial infections. The spectrum of pediatric Chlamydia trachomatis infection includes neonatal inclusion conjunctivitis, infantile pneumonia, occasional respiratory or genital tract infections in older children and sexually transmitted diseases in adolescents. The role of maternal chlamydial infection in prematurity and in perinatal death is currently an area of active study. We outline the current knowledge of the biologic characteristics of C. trachomatis, the epidemiologic features of chlamydial infection, and the clinical aspects, diagnosis and treatment of neonatal chlamydial infections.

Chlamydia Infections↗
PubMed1989

Replication of measles virus in cultured human thymic epithelial cells.

Measles virus can replicate in cultures of both infantile and fetal human thymic epithelial cells. Virus-induced cytopathology including syncytium formation was first evident around 24 hr after viral inoculation of these cultures. At the same time, the cultures began to lose their characteristic thymus-like organizational structure. Viral antigens were detected in infected cells by indirect immunofluorescence, and the presence of progeny virions was demonstrated in culture fluids.

Animals↗
PubMed1989

Replication of cytomegalovirus in human thymic epithelial cells.

Cytomegalovirus (CMV) has often been cited as a cause of immune suppression in children, yet little is known of the mechanisms through which this agent might affect immune function. We have succeeded in using CMV to productively infect cultured human fetal and infantile thymic epithelial (TE) cells. Morphological changes were apparent by 2-4 days after viral inoculation. CMV-related early antigen (EA) and late antigen (LA) were detected by immunofluorescence after 8 days, and progeny infectious CMV was recovered from culture media after 12-17 days. TE cells that reacted with monoclonal antibodies specific for keratin and for GQ ganglioside were predominant throughout the culture period. In contrast, infection by CMV resulted in a significant decrease in numbers of cells reactive with monoclonal antibodies specific for mesoderm-derived components. Inoculation of TE cells with CMV also caused a diminution in levels of detectable interleukin-1 (IL-1)-related antigen by 17 days after infection.

Animals↗
PubMed1989

Infection of cultured human thymic epithelial cells by human immunodeficiency virus.

We have succeeded in growing the HTLV-IIIB strain of human immunodeficiency virus type 1 (HIV-1) in cultured human thymic epithelial (TE) cells. Expression of the HIV-1 proteins p17 and p24 was detected by immunofluorescence and reached a peak at 3 days after infection. Antigen capture and reverse transcriptase assays were used to detect HIV-1 in culture fluids, with positive results also being realized. The infection was cytolytic; cellular disarrangement, increased numbers of Hassall's corpuscles, and giant cells first appeared in monolayers of TE cells at 2 days after inoculation. By 4 days these changes were increased, and by 7 days, retraction and involution of TE cells were evident. The infection of TE cells by HIV-1 was blocked by preincubation with monoclonal OKT4A antibodies directed against CD4 target molecules.

Antibodies, Monoclonal↗
PubMed1989

Infection of cultured human fetal pancreatic islet cells by rubella virus.

A high incidence of insulin-dependent diabetes mellitus (IDDM) has been reported in children and young adults previously afflicted with congenital rubella syndrome (CRS). The authors have studied the effect of rubella virus infection on human pancreatic islet cells in tissue culture. These experiments were performed with the use of both monolayers and free-floating human fetal islets of Langerhans tissue. Levels of production of immunoreactive insulin by islet cells that had been infected by rubella virus were lower than those observed in control cultures, under conditions of high glucose concentration (11.1 mmol/L) in the medium. The presence of rubella viral antigens in human pancreatic beta and non-beta cells was demonstrated by double-label immunofluorescence. These results suggest that rubella virus can infect human pancreatic islet cells and that such infection may lead to significant reductions in levels of secreted insulin.

Antigens, Viral↗
PubMed1989

Effects of infection by HIV-1, cytomegalovirus, and human measles virus on cultured human thymic epithelial cells.

A tissue culture system for the growth of human fetal and infantile thymic epithelial (TE) cells has been established and characterized. We have investigated the effects of infection of these cells by human cytomegalovirus (CMV), measles virus, and human immunodeficiency virus type-1 (HIV-1). In the case of CMV, morphological changes were apparent by 2-4 days after viral inoculation of infantile TE cells. CMV-related antigens were detected by immunofluorescence after 12 days, and progeny infectious CMV was recovered from culture media after 18 days. Following infection by measles virus, distinctive, multinucleated giant TE cells appeared in both cultures of fetal and infantile TE cells. Measles virus-inoculated TE cells displayed an altered phenotype, as revealed by reaction with monoclonal antibodies with specificity for a variety of TE markers. Finally, infection of TE cells by HIV-1 resulted in cellular disarrangement, increased numbers of Hassall's corpuscles, and multinucleated giant cells. An increase in the number of cells reactive with monoclonal antibodies, specific for Hassall's corpuscles, was observed in the case of cells infected by either measles virus or HIV-1. These findings suggest that a variety of different viruses can successfully infect thymic epithelial tissue. Because of the important role of the thymus in development of the immune system, it is reasonable to conclude that viral infection of thymic tissue might play an important role in virus-mediated suppression of immune responsiveness.

Acquired Immunodeficiency Syndrome↗
PubMed1988

Effect of co-incubation with cytomegalovirus on growth of interleukin 2-dependent lymphocytes.

We have tested the ability of human cytomegalovirus (CMV) to interfere with the interleukin-2 (IL-2)-dependent proliferation of T lymphocytes in long-term tissue culture. The results indicate that CMV was able to establish an apparently abortive infection in approximately 40% of such cells, although productive viral replication could not be detected, and was able to impede cellular proliferation almost completely. The addition of high concentrations of exogenous IL-2 to cultures of CMV co-incubated cells was not readily able to overcome the anti-proliferation inhibitory effect induced by this virus. Exposure to CMV led to an approximate 50% decrease in the number of cells which expressed Tac Ag, or IL-2 receptor, at the cell surface.

Cell Division↗
PubMed1988

Viral infection of human fetal islets of Langerhans. Replication of human cytomegalovirus in cultured human fetal pancreatic islets.

Tissue monolayer cultures of human fetal islets of Langerhans were infected with human cytomegalovirus (CMV). On the fourth day after inoculation, morphologic changes of monolayers were observed, including rounding up and floating of many cells. In addition, after this time CMV late antigen (LA) was detected in the inoculated cells. On the seventh day, CMV was recovered from the culture medium, and infected beta cells were identified by use of a double-label antibody technique. However, CMV apparently did not cause direct destruction of beta cells nor did infection by CMV lead to changes in production of insulin as measured by radioimmunoassay. Thus, despite the fact that CMV can successfully infect a variety of cells in fetal islets of Langerhans, the absence of a significant effect on beta cells does not support the notion that congenital CMV infection is involved in the origin of insulin-dependent diabetes mellitus.

Antigens, Viral↗
PubMed1988

Infection of human thymic epithelial cells by human cytomegalovirus and other viruses: effect on secretion of interleukin 1-like activity.

Cultures of human thymic epithelial (TE) cells are able to produce a interleukin 1 (IL-1) like activity. This IL-1 activity can be detected either using mouse thymocytes in a traditional IL-1 assay, or using thymic lymphocytes obtained from cases of pediatric cardio-vascular surgery. Production of IL-1 activity by TE cells was found to be maximal between 3 and 4 weeks after culture initiation. Human thymocytes worked best as targets in an IL-1 assay, when these cells were derived from donors younger than 1 year of age. Infection of human TE cells by any of human cytomegalovirus, herpes simplex virus type 2, adenovirus 7, Coxsackie B1, and respiratory syncytial virus led to marked reductions in the ability of these cells to secrete measurable IL-1 activity. In the case of TE cells infected by cytomegalovirus, respiratory syncytial virus, and Coxsackie B1, this abrogation of production of IL-1 activity occurred in the absence of any obvious virus-induced cytopathic effect.

Cells, Cultured↗
PubMed1988

The effect of cyclosporine A on infection of susceptible cells by human immunodeficiency virus type 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.

CD4-Positive T-Lymphocytes↗
PubMed1988

Clinical and etiological studies of chlamydial conjunctivitis in Sapporo, Japan.

Chlamydia trachomatis was isolated from 21.5% (61/284 cases) of the patients with conjunctivitis seen in an eye clinic in Sapporo, Japan, during a recent 4-year period. The frequency was the highest in newborn babies and the 20- to 29-year-old age group. The early incidence of neonatal conjunctivitis suggested that transmission had occurred at delivery. Isolation by tissue culture is the most sensitive method for detection of this condition but the Micro Trak direct fluorescence antibody test is more practical. The detection of a specific IgG antibody and IgA antibody against chlamydia in human sera and in tears showed that patients with chlamydial conjunctivitis had the antibody before the onset of conjunctivitis.

Adolescent↗
PubMed1986

Relationship between Chlamydia trachomatis infection and elevated serum immunoglobulin M levels in premature infants.

Serum immunoglobulin M (IgM) antibodies to Chlamydia trachomatis and to human cytomegalovirus (CMV) were detected by enzyme-linked fluorescence assay and enzyme-linked immunosorbent assay, respectively in 19 premature infants with chronic lung diseases, in 43 extremely low birth weight premature infants and in 123 neonates with elevated serum IgM levels. Ten of the 19 premature infants with chronic lung diseases had elevated serum IgM levels, and five had IgM antibodies to Chlamydia trachomatis. Three of the 43 extremely low birth weight premature infants had elevated serum IgM levels, and two had IgM antibodies to Chlamydia trachomatis. Three of the 123 neonates with elevated serum IgM levels (excluding those with chronic lung diseases and extremely low birth weight) had IgM antibodies to CMV. These results suggest that chronic lung diseases in low birth weight infants might be caused by intrauterine Chlamydia trachomatis infection.

Antibodies, Bacterial↗
PubMed1986

Chronic respiratory disease in premature infants caused by Chlamydia trachomatis.

The relation between chronic respiratory disease and infection with Chlamydia trachomatis in premature infants was investigated to ascertain the aetiological importance of intrauterine C trachomatis infection and chronic respiratory disease in premature infants. Serum IgM antibodies against C trachomatis were determined by enzyme linked fluorescence assay. Sections of lung tissues obtained by biopsy and at necropsy were also tested for the presence of antigens using fluorescein conjugated monoclonal antibodies to C trachomatis. Of 16 sera from premature infants with chronic respiratory diseases clinically diagnosed as bronchopulmonary dysplasia or the Wilson-Mikity syndrome, five had IgM antibodies to C trachomatis L2 strain by enzyme linked fluorescence assay (titre greater than or equal to 1/500). Of 37 sera from premature infants with extremely low birth weights, two had IgM antibodies to C trachomatis. No specific IgM antibody was detected in 31 neonates who showed raised serum IgM concentrations but who did not have respiratory tract symptoms. C trachomatis was identified from two specimens of lung tissue obtained at necropsy from premature infants with chronic respiratory disease positive for IgM antibody. These findings indicate the aetiological importance of intrauterine C trachomatis infection in chronic respiratory disease in premature infants.

Chlamydia Infections↗