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Biomedical subjects

A Garza

Publications and source records attributed to A Garza.

At least 19 recordsLinked to original sources
PubMed2000

Spatial control of cell differentiation in Myxococcus xanthus.

Myxococcus xanthus develops species-specific multicellular fruiting bodies. Starting from a uniform mat of cells, some cells enter into nascent fruiting body aggregates, whereas other cells remain outside. The cells within the fruiting body differentiate from rods into spherical, heat-resistant spores, whereas the cells outside the aggregates, called peripheral cells, remain rod-shaped. Early developmentally regulated genes are expressed in peripheral cells as well as by cells in the fruiting bodies. By contrast, late developmental genes are only expressed by cells within the nascent fruiting bodies. The data show that peripheral cells begin to develop, but are unable to express genes that are switched on later than about 6 h after the start of development. All of the genes whose expression is limited to the fruiting body are dependent on C-signaling either directly or indirectly, whereas the genes that are equally expressed in peripheral rods and in fruiting body cells are not. One of the C-signal-dependent and spatially patterned operons is called dev, and the dev operon has been implicated in the process of sporulation. It is proposed that expression of certain genes, including those of the dev operon, is limited to the nascent fruiting body because fruiting body cells engage in a high level of C-signaling. Peripheral cells do less C-signaling than fruiting body cells, because they have a different spatial arrangement and are at lower density. As a consequence, peripheral cells fail to express the late genes necessary for spore differentiation.

Artificial Gene Fusion↗
PubMed2000

Domestic violence in a university emergency department.

BACKGROUND: We attempted to determine the prevalence and demographics of domestic violence (DV) among male and female patients in a university emergency department (ED). METHODS: The validated Index of Spouse Abuse (ISA) was used. Patients aged 18 years or older seen during 28 randomly selected 4-hour shifts were eligible. RESULTS: Of the 97 participants in the study, 57 were female. One man and 3 women were victims of present physical DV, with 1 male and 2 female victims of present nonphysical abuse. Three of the 40 men and 22 of the 57 women had been victims of past physical violence. One man and 15 women had been victims of past nonphysical abuse. Alcohol use, suicidal ideation, family history, and psychiatric history were all strongly correlated with DV. CONCLUSIONS: The prevalence of DV past was significantly higher in the females. Present violence was more rare and less than that reported in other ED studies.

Adult↗
PubMed1999

Ethnicity affects the postprandial regulation of glycogenolysis.

We investigated the effect of nutrient intake on glucose metabolism in normal Mexican-Americans (n = 6) and European-Americans (n = 6). Subjects were studied after an 18-h fast and after 5-6 h of ingestion of hourly meals that supplied 6.35 or 12.75 micromol glucose. kg(-1). min(-1). Endogenous glucose production (EGP), gluconeogenesis (GNG), and glycogenolysis (GLY) were estimated by mass isotopomer analysis with [U-(13)C]glucose infusions. Fasting EGP, GNG, and GLY did not differ between the groups. Food ingestion lowered the molar rate of GNG by only 31%. However, while consuming the lower quantity of nutrients, Mexican-Americans had higher plasma glucose (P < 0.05), a 39% higher rate of EGP (P < 0.05), and a 68% (P < 0.025) higher rate of GLY than the European-Americans. At the higher intake, EGP and GLY were suppressed completely in both groups. There was a linear relationship between insulin concentrations, EGP, and GLY in both groups, but the slope of the line was significantly (P < 0.05) greater in the European-Americans. We conclude that the sensitivity of GLY to nutrient intake differs between ethnic groups and that this may play a role in the increased predisposition of Mexican-Americans to type II diabetes.

Adult↗
PubMed1999

Childhood vaccines: an update.

Immunizations are the best weapon against diseases that once devastated children, but far too few kids are getting them as needed. To help you protect your pediatric patients, we present the newest guidelines on which vaccines to give, when and how to give them, and to whom.

Adolescent↗
PubMed1998

Injection of T-cell receptor peptide reduces immunosenescence in aged C57BL/6 mice.

Previous studies established that retrovirally infected young mice produced large amounts of autoantibodies to certain T-cell receptor (TCR) peptides whose administration diminished retrovirus-induced immune abnormalities. C57BL/6 young (4 weeks) and old (16 months) female mice were injected with these same synthetic human TCR V beta 8.1 or 5.2 peptides. Administration of these autoantigenic peptides to old mice prevent immunosenescence, such as age-related reduction in splenocyte proliferation and interleukin-2 (IL-2) secretion. TCR V beta peptide injection into young mice had no effect on T- or B-cell mitogenesis and IL-4 production while modifying tumour necrosis factor-alpha (TNF-alpha), IL-6, and interferon-gamma (IFN-gamma) secreted by mitogen-stimulated spleen cells. TCR V beta injection also retarded the excessive production of IL-4, IL-6 and TNF-alpha induced by ageing. These data suggest that immune dysfunction and abnormal cytokine production, induced by the ageing process, were largely prevented by injection of selected TCR V beta CDR1 peptides.

Aging↗
PubMed1997

Failure of HPV E6 to rapidly degrade p53 in human HeLa x PNET cell hybrids.

The ability of the E6 protein from high risk human papillomaviruses (HPVs) to degrade p53 via the ubiquitin pathway plays a major role in the development of cervical carcinomas. We have previously generated cell hybrids between a p53 null peripheral neuroepithelioma (PNET) cell line and a cervical carcinoma HeLa cell line which exhibits efficient E6-mediated degradation of p53. All of the resulting hybrids expressed HPV 18 E6 from the HeLa parent and some of the hybrids additionally expressed HPV 16 E6. Surprisingly, in spite of abundant E6 expression, the hybrids expressed relatively high steady-state levels of the wild-type p53 protein. We then examined the hybrids to determine whether other components of the E6-mediated degradation pathway were missing or nonfunctional. Specifically, we determined that the E6-associated protein (E6-AP), essential for E6-mediated degradation, was expressed. We further verified that these hybrids had a functional ubiquitination pathway, which suggests that this phenomenon is not due to a general defect in this pathway. We therefore conclude that other unidentified, possibly cell-specific factors can play a role in the E6-mediated degradative process and may act to inhibit this process.

DNA Damage↗
PubMed1997

Analysis of autoantibodies to T-cell receptors among HIV-infected individuals: epitope analysis and time course.

Individuals seropositive for human immunodeficiency virus type 1 (HIV) express elevated levels of autoantibodies (AAbs) directed against recombinant T-cell receptors (TCRs) and synthetic peptide epitopes duplicating beta chain markers. We performed longitudinal studies of anti-TCR AAbs in HIV-1-infected individuals, making comparisons with uninfected sera and sera from other individuals infected with a nonviral agent. We determined levels of autoantibodies by titration using enzyme-linked immunosorbent assay (ELISA) and developed a means for characterizing "autoantibody CDR recognition spectrotypes" for individual sera. Antibody levels against certain defined synthetic epitopes were substantially elevated in HIV-infected subjects relative to reactivities by control groups. Individual sera showed relatively high AAb levels to a subset of CDR1 peptide epitopes. Two patients who subsequently developed AIDS showed particular reactivity to Vbeta2.1, 8.1, 10.1, and 22.1 epitopes. Our results show that production AAbs to TCR Vbeta epitopes is a general consequence of HIV infection. The response is individual but shows some restriction and shifts in AAb subpopulations often occur with time.

Adult↗
PubMed1997

Binding of human IgG myeloma proteins to autologous T-cell receptor determinants.

IgG myeloma proteins (MPs) produced by monoclonal plasma cells derived from B2 lymphocytes have been reported to bind to various autoantigens but the binding generally has been of low affinity. Moreover, T cells from some multiple myeloma patients can respond specifically to idiotypes of their own paraproteins. We analyzed the capacity of more than 20 human IgG MP to bind, a recombinant single-chain molecule containing complete V beta 8.1 and V alpha 1 structures, sets of synthetic peptide epitopes corresponding to a complete TCR beta chain, and a set of CDR1 epitopes corresponding to 24 human V beta gene products, and intact monoclonal T cells. Two of 20 MPs bound strongly to the recombinant TCR. Five of the same set, including these, bound to a synthetic epitope corresponding to the CDR1 segment. On a mass basis, the binding was approximately 1000-fold greater than that of pooled polyclonal IgG. The binding activity was confined to the Fab fragment and was specifically inhibitable by appropriate peptide determinants. Spectrotypic analysis using a set of CDR1 epitopes indicated that individual proteins showed characteristic binding patterns ranging from highly specific to relatively promiscuous. Highly reactive MPs also bound to TCR on intact cells in immunocytofluorescence by flow cytometry. These results are consistent with the relatively frequent occurrence of autoantibodies to TCR determinants and indicate that MPs can be derived from this autoantibody subset.

Amino Acid Sequence↗
PubMed1997

Hepatitis update.

Explore the source record for details and available documents.

Hepatitis, Viral, Human↗
PubMed1994

Neuron-specific enolase expression during eye development in the chicken embryo.

Neuron-specific enolase has been used by others as a marker for the identification of cells of presumed neural crest origin in the human eye. The contributions of neural crest to the ocular tissues have been studied most definitively in the chicken embryo. The developing chicken eye was therefore chosen to further investigate the usefulness of neuron-specific enolase as a neural crest marker. Chicken embryos of various development stages were processed for the immunohistochemical localization of neuron-specific enolase with two different specific antisera. The nerve fiber layer of the neural retina and the optic nerve reacted positively. The first weak staining was found at day 10; it became rapidly stronger during the next 2 days. A positive reaction was also observed in the ciliary ganglion. In contrast, no staining was found in tissues of known neural crest origin. Cornea, sclera, trabecular tissues and iris stroma remained negative throughout the developmental stages studied. Therefore, neuron-specific enolase can not be used as a reliable marker of neural crest derived cells, at least in the chicken embryo. Unexpectedly the lens epithelium showed moderate neuron-specific enolase activity beginning on day 5. alpha-Enolase is an important crystallin in the lens of some species, particularly the turtle. It has also been demonstrated to be present in the chicken lens in a fairly high concentration. It is possible, that neuron-specific or gamma-enolase has a similar role in the chicken lens.

Animals↗
PubMed1994

Immunohistochemical visualization of fibrin in anterior chamber angle after YAG laser capsulotomy.

Hematoxylin and eosin staining of rabbit eyes after YAG laser anterior capsulotomy showed amorphous substances at the anterior chamber angle. The amorphous substances were identified as fibrin by immunohistochemical methods. This finding indicated that the obstruction of aqueous humor flow by fibrin could be responsible for the elevation of intraocular pressure following YAG laser anterior capsulotomy.

Animals↗
PubMed1992

Biologic markers in hospital workers exposed to low levels of ethylene oxide.

Operators of hospital sterilizers that use ethylene oxide were studied to determine if there was a relationship between exposure and a battery of biological markers. A total of 73 workers from nine hospitals in the United States (U.S.) and one hospital in Mexico City was evaluated for ethylene oxide exposure during four months prior to collection of peripheral blood. The frequency of hemoglobin adducts (p = 0.0006) and sister-chromatid exchanges (SCEs) (p = 0.002) increased with cumulative exposure to ethylene oxide in U.S. subjects when controlling by regression analysis for various confounding factors, including cigarette smoking. Hemoglobin adducts, but not SCEs, were also increased in Mexican subjects (p = 0.0012). Chromosomal micronuclei showed no consistent relationship with exposure. The U.S. study participants were classified by four-month cumulative exposure levels of 10 ppm-h (n = 8), greater than 0 to 32 ppm-h (n = 32) and greater than 32 ppm-h (n = 11) of ethylene oxide exposure. The group with an exposure of greater than 32 ppm-h had an increased frequency of hemoglobin adducts (p = 0.002) and SCEs (p = 0.0001) compared to the nonexposed group. The estimated mean of the 8-h time-weighted average (8-h TWA) exposure levels for the highest U.S. exposure group (greater than 32 ppm-h) was 0.16 +/- 0.007 ppm (mean +/- SD). A similar exposure-related differential was observed in the Mexican subjects for hemoglobin adducts (p = 0.04) but not for SCEs. The latter finding may have been due to longer shipping times for the specimens in the cytogenetic assays. The estimated mean of the 8-h TWA exposure levels for the highest Mexican exposure group (greater than 32 ppm-h) was 0.48 +/- 0.08 ppm. This study is the third to suggest that exposures less than the U.S. OSHA standard of 1 ppm 8-h TWA result in biochemical and biologic changes. It is not known whether these changes may be indicative of increased risk of disease; however, they do appear to reflect exposure to relatively low levels of ethylene oxide. The exact meaning of these changes is unknown.

Adult↗
PubMed1990

Comparison of tartrate resistant acid phosphatase in a giant cell bone tumor and a spleen infiltrated with hairy cells.

Acid phosphatase (E.C.3.1.3.2) in a giant cell bone tumor and a spleen infiltrated with hairy cells was extracted by citrate buffer and then by 0.3 mol/L NaCl. The cationic acid phosphatase in the crude extract was isolated by CM-cellulose chromatography, and further separated by high pressure liquid chromatography. The majority of the tartrate resistant acid phosphatase in the hairy cell spleen was unabsorbed on CM-cellulose and was insensitive to iron. A much larger portion of the acid phosphatase in the bone tumor, than in the spleen, was cationic and was eluted from the column by 0.8 mol/L NaCl. The cationic acid phosphatase was further separated into consecutive peaks of acid phosphatases with different sensitivity to iron. A major portion of acid phosphatase in the giant cell bone tumor was enhanced by iron, while the amounts of iron-enhanced and iron-insensitive acid phosphatase were about the same in the spleen. The differences of the phosphatases in these two types of pathologic specimens indicate the occurrence of two types of enzymes with different biological significance.

Acid Phosphatase↗