Biomedical subjects

Y Tang

Publications and source records attributed to Y Tang.

458 records · Page 26Linked to original sources

PubMedDate not supplied

Immune responses to a recombinant human immunodeficiency virus type 1 (HIV-1) gpl60 vaccine among adults with advanced HIV infection. Massachusetts gp160 Working Group.

OBJECTIVE: To assess immunogenicity of recombinant human immunodeficiency virus type 1 (HIV-1) envelope vaccine (rgp160) in late HIV infection. STUDY DESIGN/METHODS: HIV-infected volunteers (n = 142), with CD4+ T lymphocyte counts of <400/mm3, were enrolled in a dose-comparison, open-label trial with stratification by CD4+ cell count, randomization to a primary series at two dose levels, and a sub-group receiving interferon-gamma (IFN-gamma) as an adjuvant. Subjects received booster doses of vaccine over a follow-up period of 18-28 months. RESULTS: At 6 and 12 months, 36% and 38% of participants, respectively, had new or augmented antibody titers (> or =4-fold increase) against one or more gpl60 epitopes (C1, V3, C41, 448C). Delayed-type hypersensitivity (DTH) to intradermal gpl60, initially not present in any participant, developed after immunization in 41%, with higher prevalence in participants receiving the lower dose of vaccine. Both antibody and skin test responses occurred in 20-25% of vaccine recipients. Virtually all antibody and skin test responses occurred in participants with initial CD4+ cell counts of >100 cells/mm3. IFN-gamma had no significant effect on immune response. Immunization was well tolerated. Trends in CD4+ cell count, clinical events, and laboratory findings correlated with baseline CD4+ T lymphocyte count stratum and not with immunization regimen. Opportunistic conditions occurred at expected rates. Viral load trends (p24 antigen in all participants and viral RNA by reverse transcription-polymerase chain reaction in a subset of 26 participants) did not correlate with immunization regimen. CONCLUSION: Immunization of patients with advanced HIV infection with rgpl60 resulted in new and augmented humoral and DTH responses, without unexpected significant adverse events or evident clinical benefits attributable to immunization.

AIDS Vaccines↗

PubMedDate not supplied

Characterization of a small round virus associated with the poult enteritis and mortality syndrome.

A small round virus (SRV) identified and isolated in our laboratory from intestinal samples of poults affected with the poult enteritis and mortality syndrome was further characterized. The SRV was propagated in turkey embryos and purified by differential and isopycnic ultracentrifugation. The size of the SRV was 30-32 nm in diameter. The buoyant density of the SRV in cesium chloride was between 1.34 and 1.36 g/cm3. It was resistant to chloroform treatment, stable at pH 3.0, and resistant to heat treatment. Attempts to propagate the SRV in turkey embryo kidney, turkey kidney, Caco-2, Vero, and BGM-70 cells were unsuccessful. Analysis of the SRV capsid proteins by sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed three polypeptides with molecular weights of 34.5, 31, and 28 kD. Genome analysis of the SRV showed that the SRV had a single-strand RNA genome about 7500 nucleotides in length. Reverse transcription-polymerase chain reactions (RT-PCRs) with primers specific to conserved sequences of enteroviruses yielded products with expected sizes. However, sequence analysis of the RT-PCR products showed that there was no similarity between the sequences and that of enteroviruses. RT-PCR with primers specific to the 3' end of a SRV RNA genome yielded products with expected sizes. These products were sequenced and found to contain 669 nucleotides, excluding the polyadenylated tail. Sequence analysis indicated that the SRV shared 38.18% amino acid identity in the C-terminal capsid precursor protein and 41.26% nucleotide identity of the 3' end of turkey astrovirus RNA genome (Genbank accession no. Y15936). We concluded that the SRV is a member of the astrovirus family.

Amino Acid Sequence↗

PubMedDate not supplied

Expansion of hepatic and hematopoietic stem cells utilizing mouse embryonic liver explants.

Ex vivo embryonic liver explant culture is a novel and attractive approach to obtain abundant hepatic and hematopoietic stem cells. Gene therapy of autologous hepatic and hematopoietic stem cells represents an alternative therapeutic approach to liver transplantation for genetic and metabolic disorders. In this study we characterize the growth and differentiation of hepatic stem cells utilizing embryonic liver cultures. Day 9.5 liver buds are microdissected and cultured under specific conditions. Modulation of growth conditions by addition of hepatocyte growth factor, Flt-3 ligand, and stem cell factor leads to enrichment of hepatic progenitor cells in embryonic liver explants. Under these conditions, we also demonstrate the role of a novel marker PRAJA-1 to identify hepatic stem cells and transitional hepatocytes. Utilization of dexamethasone enhanced pseudolobule formation with increased hepatocytic and biliary differentiation. Transforming growth factor-beta leads to enrichment of biliary cells in the culture. Gut formation is enhanced in the presence of interleukin-3 and blood formation by increasing the mesodermal tissue in these cultures. We also show increased retroviral-mediated expression of the green fluorescent protein expression in the expanded hepatic and hematopoietic stem cells under different culture conditions. Thus, the embryonic liver explant culture is an attractive source for hepatic progenitors and is a possible step towards generating nontumorigenic immortalized hepatocytes with possible transplantation applications.

Animals↗

PubMedDate not supplied

Age-related change of the neuronal number in the human medial vestibular nucleus: a stereological investigation.

An unbiased stereological method was used to assess the effect of aging on the number of neurons in the human medial vestibular nucleus. We studied 13 normal brainstem specimens (age at death from 40 to 93 years) that were part of a prior study that counted neuronal profiles and used a correction factor to estimate the number of neurons in the human vestibular nucleus. On average, we found 151.10(3) (CV = 0.15) neurons in the medial vestibular nucleus, which is 18% more than that in the prior study. Regression analysis showed a significant decrease in the number of neurons with aging. This age-related neuronal loss in the vestibular nucleus could have important functional implications regarding the well-known deterioration in balance that occurs with aging.

Adult↗

PubMedDate not supplied

Clonal outgrowths of T and B cells in SCID mice reconstituted with cells from mice with MAIDS.

Murine acquired immunodeficiency syndrome (MAIDS), induce in mice by a defective murine retrovirus (BM5def), is characterized by development of severe immunodeficiency and polyclonal lymphoid proliferation which progress to yield oligoclonal populations of T and B cells. Oligoclonal populations transferred to SCID mice grew as clonal CD4+ T cell or B cell lineage transplants having one or more unique clonal integrations of BM5def. In some cases, spleens of single donor mice were shown to contain both B cell and T cell lineage clones that could be transferred individually after separation and were clonally unrelated. Successful transplants were obtained from oligoclonal populations as early as 63 days after infection. Mouse strains both sensitive or moderately resistant to MAIDS yielded clonal transplants.

Animals↗

PubMedDate not supplied

Upregulation of Gfi-1, a gene involved in IL-2-independent growth of T cells, in a murine retrovirus-induced immunodeficiency syndrome.

BACKGROUND: A prominent feature of retrovirus-induced immunodeficiency in mice (MAIDS) is early polyclonal activation of CD4+ T cells followed by the appearance of monoclonal lymphomas marked by clonal proviral integrations. These events appear to occur independent of interleukin-2 (IL-2), suggesting the activity of an alternative growth-promoting pathway. We studied the possible contributions to T cell expansion of a gene, Gfi-1, previously shown to confer IL-2 independence to rat T cell lymphomas. MATERIALS, RESULTS, CONCLUSIONS: We studied 17 mice with MAIDS that had clonal populations of T cells. Proviral integrations at Gfi-1 were detected in two animals. These integrations were associated with enhanced transcription of Gfi-1. Unexpectedly, elevated levels of Gfi-1 transcripts were also observed in four T cell lymphomas without detectable integrations at this locus. This suggests that IL-2-independent T cell growth in MAIDS may be driven by transcriptional activation of Gfi-1 by proviral insertion or transactivation.

Animals↗

PubMedDate not supplied

In vitro study of nicotine release from smokeless tobacco.

Four brands (Copenhagen Snuff, Skoal Bandit Classic, Skoal Wintergreen Long Cut, and Skoal Wintergreen Fine Cut) of smokeless tobacco products were tested for their rate of nicotine release into artificial saliva via direct contact or through a dialysis bag. Nicotine was determined by reversed-phase liquid chromatography. When samples were in direct contact with artificial saliva, most of the nicotine was released from the tobacco in the first minute. Nicotine release from Skoal Bandit Classic, marketed as smokeless tobacco in a sachet, was slower with the sachet intact than without the sachet. When smokeless tobacco and artificial saliva were placed inside a dialysis bag, nicotine release was much slower and primarily depended upon the permeability of the dialysis membrane. Although total nicotine was lowest for Skoal Bandit Classic, little difference was seen in nicotine release rates among the brands tested. When smokeless tobacco was placed in dialysis bags with artificial saliva outside, a significant difference was seen in rates of nicotine migration through the membrane. In this model, nicotine release from Copenhagen Snuff was much faster than from Skoal Bandit Classic with or without the sachet. This difference may be related to the pH of the smokeless tobacco products.

Absorption↗

PubMedDate not supplied

Morphological evidence for the location of calcitonin gene-related peptide (CGRP) immunoreactivity in rat lymphocytes.

Calcitonin gene-related peptide (CGRP) is widely distributed in sensory neurons and nerve fibers. It was shown recently in our laboratory that there was CGRP-immunoreactivity (CGRP-ir) in extract of rat lymphocyte of thymus and mesenteric lymph node by radioimmunoassay and reversed-phase HPLC. The aim of this study was to detect the CGRP-ir location in the rat lymphocyte by immunocytochemical method. Single cells isolated from thymus and mesenteric lymph node of male Wistar rat (200-250 g) were suspended in RPMI-1640 medium. After adhesion to plate wall and through nylon wool fiber columns, T cell-riched suspension was obtained. Immunocytochemical ABC method was performed in cell suspension, the specific antiserum (1:200 diluted) was rabbit anti-human CGRP. The cells were examined under light microscope after smeared on glass slide by Shandon Cytospin. The results showed that some lymphocytes were CGRP-ir positive. The positive granules were seen as ring, plaque, cap or spot distributing on the surface or inside the cell. The results indicate that CGRP-ir may be located in some rat T lymphocytes. This work provides new information about the interaction between the nervous and the immune systems. The functional significance of CGRP located in lymphocytes needs to be further studied.

Animals↗