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Biomedical subjects

M M Garcia

Publications and source records attributed to M M Garcia.

At least 55 records · Page 3Linked to original sources
PubMed1995

Growth of a microprolactinoma to a macroprolactinoma during estrogen therapy.

Following presentation and diagnosis, microprolactinomas usually follow a benign course and rarely progress to macroprolactinomas. However, clinically significant enlargement of prolactinomas during pregnancy, presumably related to estrogen stimulation, has been reported. This report describes a patient with amenorrhea and hyperprolactinemia and a microadenoma by computed tomography scan who developed a macroprolactinoma within 10 months after being placed on estrogen therapy. We propose that exogenous estrogen administration in this patient most likely promoted growth from a microprolactinoma to a macroprolactinoma. This case emphasizes the primary role of dopaminergic agonist therapy in the management of pathological hyperprolactinemia and suggests that estrogen therapy should not be casually given to patients with known prolactinomas to avoid the possibility of promoting tumor growth. A correlate of this approach is that caution regarding estrogen therapy should also be exercised in patients with idiopathic hyperprolactinemia who might have an occult microprolactinoma which could grow following estrogen stimulation. If estrogen treatment is deemed necessary, dopaminergic agonist therapy should also be used prophylactically to prevent potential tumor growth due to estrogen. The patient should then be carefully monitored with periodic serum PRLs and for the development of clinical manifestations suggesting pituitary growth. An imaging study should be performed when there is a significant increase in serum PRL or the development of new clinical manifestations.

Amenorrhea↗
PubMed1995

Humoral immune responses in acute schistosomiasis mansoni: relation to morbidity.

An analysis of 25 individuals simultaneously exposed to cercariae of Schistosoma mansoni showed that morbidity (measured by the clinical/sonographic index) was more severe in patients with high-level egg output, irrespective of age or intensity of water contact. High levels of IgM and IgG antibodies to keyhole limpet hemocyanin and of IgA antibody to soluble egg antigen were documented predominantly during the acute phase of illness. Increased levels of these antibodies and of IgM antibody to soluble egg antigen correlated positively with morbidity after adjustment for age and intensity of water contact.

Acute Disease↗
PubMed1995

Protein shift and antigenic variation in the S-layer of Campylobacter fetus subsp. venerealis during bovine infection accompanied by genomic rearrangement of sapA homologs.

Campylobacter fetus subsp. venerealis isolated from a case of human vaginosis was inoculated into the uterus of a C. fetus-negative heifer. Isolates obtained weekly from the vaginal mucus exhibited variations in high-molecular-mass-protein profiles from that of the original inoculum, which had a dominant 110-kDa S-layer protein. Immunoblots of the weekly isolates with monoclonal antibody probes against the 110-kDa S-layer protein and other C. fetus S-layer proteins demonstrated antigenic shifts. Genomic digests of the isolates probed with a 75-mer oligonucleotide of the conserved sapA region also indicated that antigenic variation of the S-layer is accompanied by DNA rearrangement.

Animals↗
PubMed1995

Comparisons of antibiotic combinations to control Pseudomonas aeruginosa in bovine semen.

Raw semen experimentally contaminated with 10(6) Pseudomonas aeruginosa cells per milliliter was processed for use in artificial insemination (AI) using three different antibiotic combinations: a) gentamicin, lincomycin, spectinomycin and tylosin (GLST) directly added to contaminated raw semen followed by dilution with whole milk or egg yolk Tris containing GLST; b) penicillin, streptomycin, lincomycin, spectinomycin and minocycline (PSLSM) in whole milk used to dilute the contaminated raw semen followed by further dilution with glycerolated milk containing PSLSM; and c) penicillin, streptomycin, lincomycin and spectinomycin (PSLS) used with egg yolk Tris diluent in the same way as PSLSM and milk. Diluted semen was incubated at 35 degrees C for 5 or 40 min before cooling commenced. To assess the efficacy of the antibiotics in controlling P. aeruginosa, diluted semen samples were cultured for the organism before and after freezing. The GLST antibiotics added to raw semen and milk reduced the counts of P. aeruginosa before or after freezing. When egg yolk Tris was used, GLST inhibited the organism as indicated by its low growth in culture before freezing and absence of growth from samples after freezing. With PSLSM and PSLS treatments, the organism was recovered in milk and egg yolk Tris processed semen both before and after freezing. However, incubation at 35 degrees C for 40 min prior to cooling, compared to incubation of 5 min, appeared to reduce the bacterial counts after freezing.

Animals↗
PubMed1995

A study on the effect of Pseudomonas aeruginosa in semen on bovine fertility.

Two experiments were done to demonstrate whether the presence of Pseudomonas aeruginosa in bovine semen could affect fertilization and/or early embryonic development. In the first experiment, superovulated heifers were inseminated with semen naturally contaminated with P. aeruginosa (ADRI 102) or clean semen and seven day-old embryos were collected nonsurgically. The endometrium of treated heifers appeared more sensitive to the flush procedures. In experiment 2, heifers were inseminated at synchronized estrus with semen experimentally contaminated with P. aeruginosa (ADRI 102) and processed in the same way as commercial semen with antibiotics (gentamicin, lincomycin, spectinomycin and tylosin) or processed without antibiotics added. Embryos were recovered at slaughter seven days later. In general, there was no significant reduction in fertility or development of embryos in vitro as a result of relatively high numbers of P. aeruginosa in bovine semen.

Animals↗
PubMed1995

Bactericidal effects of ozone at nonspermicidal concentrations.

A study was conducted to assess the use of ozone (O3) to control pathogens or contaminants of concern to animal breeders and regulatory officials. In separate experiments, samples of fresh bovine semen and Pseudomonas aeruginosa, Escherichia coli, or Campylobacter fetus subsp. venerealis were diluted with antibiotic-free milk (10(6) sperm and 10(6) organisms/mL of diluted semen), exposed in the previous day to a constantly monitored level of 5, 10, 15, or 20 micrograms/mL of O3 for 3-5 min. After 10 min at 30 degrees C, sperm motility was assessed and the samples cooled to 5 degrees C. Two and 18 h after the beginning of cooling, aliquots of each semen sample were evaluated for motility and cultured for organisms. Reductions were observed in P. aeruginosa and E. coli colony counts of 2 logs, and in C. fetus of 5 logs, after exposure for 2 h to O3 at a concentration of 5 micrograms/mL that had a moderate effect on sperm motility (reduction of 20%). Fewer than 100 colonies, i.e., a 4 logs reduction of all bacteria, were counted after dilution with ozonized-treated milk at 20 micrograms/mL of O3. However, this concentration of O3 reduced sperm motility by 50% 10 min after dilution. The results of these experiments indicate that a concentration and exposure time to O3 can be selected to reduce P. aeruginosa, E. coli, and C. fetus in contaminated bull semen diluted with milk while having only minimal effects on sperm motility.

Animals↗
PubMed1993

Chronic morphine increases calbindin D28k in rat striatum: possible NMDA receptor involvement.

The neuronal intracellular calcium-binding protein calbindin D28k is a neurochemical marker in the striatum, normally expressed in the matrix compartment and absent from the mu-opiate receptor-enriched striosomal (patch) compartment. Because chronic treatment with morphine has been reported to increase calcium levels in synaptosomes of rat striatum, we studied effects of morphine on calbindin immunoreactivity (ir) in rat brain, using immunocytochemistry. Treatment with morphine for 5 days increased calbindin-ir in the striatal matrix, and induced intense calbindin-ir in the patch compartment. Increased calbindin-ir in patches persisted through day 14 post-morphine. Co-administration of the NMDA receptor antagonist MK-801 blocked the morphine-induced increase in calbindin-ir in patches. We suggest that chronic morphine treatment may increase calcium and calbindin levels via increased glutamatergic transmission in striatum. These findings are consistent with reports that MK-801 inhibits tolerance to morphine, and provide a possible mechanism and anatomical substrate for this inhibition.

Animals↗
PubMed1993

Protein kinase C-delta in rat brain: association with sensory neuronal hierarchies.

Originally characterized as the calcium- and phospholipid-dependent protein kinases, the protein kinases C include at least eight separate isoforms, some of which are calcium-independent and all of which are highly enriched in brain. Of the calcium-independent isoforms, the delta subspecies of protein kinase C has the most restricted complement of lipid activators and substrate specificity, suggesting that it may have a unique role in cell signalling pathways. Using immunocytochemistry, we report that the distribution of protein kinase C-delta immunoreactivity in rat brain is also restricted, being present in all sensory systems. Moreover, it is found in alternating hierarchies of sensory pathways: in all sensory systems except auditory, it is found in first- and third-order neurons, while in the auditory system, it is found in second- and fourth-order neurons. Thalamocortical systems are intensely immunoreactive, including barrel fields of the rat parietal cortex. Outside of sensory systems, protein kinase C-delta is present in cerebellum within longitudinal stripes in Purkinje neurons, and in the caudate-putamen, it appears to be associated with the striosome (patch) compartment. In contrast to all other protein kinase C isoforms, protein kinase C-delta is absent from hippocampus. These findings suggest that protein kinase C-delta may have a unique role in signal transduction in the central nervous system (CNS), especially in sensory systems.

Animals↗
PubMed1993

Structural studies of the O-antigenic polysaccharide of Fusobacterium necrophorum.

The O-specific polysaccharide component of the lipopolysaccharide produced by Fusobacterium necrophorum is of the teichoic acid type, with repeating units connected by phosphoric diester linkages. Dephosphorylation of the polysaccharide by treatment with aqueous hydrogen fluoride yielded a carbohydrate composed of a trisaccharide linked to an acidic component. This product, and the polysaccharide, were investigated by chemical methods and 1H-, 13C-, 31P- and 15N-NMR spectroscopy and the former also by fast-atom-bombardment mass spectrometry. It is proposed that the polysaccharide is composed of repeating units having the following structure, in which Fuc represents fucose (6-deoxy-galactose), Am represents an acetamidino group and Sug 2,4-diamino-2,4,6-trideoxy-D-glucose ('bacillosamine') acetylated at the 2-position and acylated with a (S)-3-hydroxybutanoic acid at the 4-position. The acid was identified as a 2-amino-2-deoxy-2-C-methyl-pentonic acid (2-amino-2-methyl-3,4,5-trihydroxypentanoic acid). The configuration of this acid remains to be determined. [formula: see text]

Abscess↗
PubMed1993

Morphological response of Bilophila wadsworthia to imipenem: correlation with properties of penicillin-binding proteins.

The penicillin-binding protein (PBP) patterns of six strains of Bilophila wadsworthia were investigated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis and subsequent fluorography of membrane preparations labelled with [3H]benzylpenicillin. The PBP profiles among the strains were similar; generally, seven to nine PBP-reactive bands could be visualized; their molecular weights ranged from 31 to 137 kDa. The relative affinities of the PBPs of four strains of B. wadsworthia for imipenem were examined and correlated with the morphological responses of the cells to imipenem. Morphological changes were examined by light and electron microscopies. Light microscopy revealed that at low concentrations (less than the MIC), imipenem induced the formation of rounded and bulging cells; rarely, elongation without filamentation was observed. In the presence of imipenem at the MIC, spheroplast formation was observed. Scanning and transmission electron microscopies revealed round forms together with larger, multilobate cells in the presence of subinhibitory concentrations of imipenem, suggesting that new growth sites were initiated while cell division was inhibited. Peeling of the outer membrane was also seen. Spheroplasts were very large (up to 30 microns in diameter) and stable in aqueous solution. Inhibition of the PBPs could be seen in the presence of low imipenem concentrations.

Bacterial Proteins↗
PubMed1993

Shift in S-layer protein expression responsible for antigenic variation in Campylobacter fetus.

Campylobacter fetus strains possess regular paracrystalline surface layers (S-layers) composed of high-molecular-weight proteins and can change the size and crystalline structure of the predominant protein expressed. Polyclonal antisera demonstrate antigenic cross-reactivity among these proteins but suggest differences in epitopes. Monoclonal antibodies to the 97-kDa S-layer protein of Campylobacter fetus subsp. fetus strain 82-40LP showed three different reactivities. Monoclonal antibody 1D1 recognized 97-kDa S-layer proteins from all C. fetus strains studied; reactivity of monoclonal antibody 6E4 was similar except for epitopes in S-layer proteins from reptile strains and strains with type B lipopolysaccharide. Monoclonal antibody 2E11 only recognized epitopes on S-layer proteins from strains with type A lipopolysaccharide regardless of size. In vitro shift from a 97-kDa S-layer protein to a 127-kDa S-layer protein resulted in different reactivity, indicating that size change was accompanied by antigenic variation. To examine in vivo variation, heifers were genetically challenged with Campylobacter fetus subsp. venerealis strains and the S-layer proteins from sequential isolates were characterized. Analysis with monoclonal antibodies showed that antigenic reactivities of the S-layer proteins were varied, indicating that these proteins represent a system for antigenic variation.

Animals↗
PubMed1992

Glucocorticoid regulation of preproenkephalin gene expression in the rat forebrain.

The effects of glucocorticoids on the levels of preproenkephalin (PPE) mRNA in the rat forebrain were analyzed with in situ hybridization and dot blots. In adrenally-intact rats, high levels of PPE mRNA, as assessed by in situ hybridization, were localized in the caudate-putamen, nucleus accumbens, central amygdala, and ventrolateral ventromedial hypothalamus (VMHVL), and low levels in the hippocampus. After adrenalectomy, the density of PPE mRNA-positive cells and the level of PPE mRNA/cell were decreased in all regions except the hippocampus. Acute treatment with corticosterone (CORT) in adrenalectomized rats increased the level of PPE mRNA/cell in the caudate-putamen and VMHVL. In intact rats, chronic treatment with CORT increased the density of PPE mRNA-positive cells in the caudate-putamen and hippocampus, and the level of PPE mRNA/cell in the caudate-putamen and nucleus accumbens. The effect of chronic CORT treatment on PPE mRNA in the striatum, amygdala, hippocampus and mediobasal hypothalamus was assessed with dot blots. Chronic CORT treatment increased PPE mRNA levels in the caudate-putamen and hippocampus. There was a good correlation between results on the effect of chronic CORT treatment on PPE mRNA levels in intact rats, obtained from dot blots and in situ hybridization. Results from this study suggest that glucocorticoids are required for the maintenance of basal PPE mRNA levels in most regions of the rat forebrain. There is, however, considerable regional heterogeneity in the effect of glucocorticoid treatment on PPE mRNA levels in adrenalectomized and intact rats. Increased PPE mRNA levels in response to high circulating levels of glucocorticoids, e.g. in stress, may have important pathophysiological consequences.

Amygdala↗
PubMed1992

Molecular discrimination of Campylobacter coli serogroup 20 biotype I (Lior) strains.

Plasmid, protein and restriction endonuclease analysis (REA) profiles and multilocus enzyme electrophoresis were used to effect a molecular discrimination of twenty-seven Campylobacter coli serogroup 20, biotype 1 (Lior) strains. These strains were not outbreak-associated but were isolated from a number of different countries and different animal and environmental sources. Each of the techniques was able to discriminate, to various degrees, between the serogroup 20, biotype 1 strains. The choice of a particular technique depends to a large extent on the level of discrimination desired, the previous experiences of the investigator and on the laboratory facilities at hand. REA profiles demonstrated the greatest degree of discrimination between these strains. Plasmid and protein profiles could discriminate reasonably well. Multilocus enzyme electrophoresis (allozyme typing) and protein profiles may prove effective in subgrouping serogroup 20, biotype 1 strains.

Animals↗
PubMed1992

Differentiation of the subspecies of Campylobacter fetus by genomic sizing.

Campylobacter fetus subsp. fetus and C. fetus subsp. venerealis are currently differentiated by tolerance to glycine and by their epidemiology. Analysis of C. fetus DNA by pulsed-field gel electrophoresis, after digestion with the restriction endonucleases SmaI and SalI, was used to differentiate between the subspecies. All strains presently identified as C. fetus subsp. fetus had a genomic size of 1.1 Mb, whereas the majority of the C. fetus subsp. venerealis strains had a genomic size of 1.3 Mb. An additional group of strains, which were previously described as C. fetus subsp. venerealis biovar "intermedius" and were able to tolerate higher concentrations of glycine than the rest of the C. fetus subsp. venerealis strains, had an average genome size of 1.5 Mb. We suggest that pulsed-field gel electrophoresis may be useful as an additional aid in the differentiation of C. fetus strains at the subspecies level.

Campylobacter fetus↗
PubMed1992

Ultrastructure and molecular characterization of Fusobacterium necrophorum biovars.

The ultrastructural features and molecular components of 18 strains of Fusobacterium necrophorum biovars A, AB and B, isolated from animal and human infections, were examined by electron microscopy, multilocus enzyme electrophoresis (MEE) and by sodium dodecyl sulfate-gradient polyacrylamide gel electrophoresis (SDS-PAGE). High resolution scanning electron microscopy revealed that the strains possessed a convoluted surface pattern. Transmission electron microscopy showed that all strains possessed a cell wall structure typical of gram-negative bacteria. Bleb formation was not uncommon. Numerous extracellular materials, resembling lipopolysaccharide (LPS) fragments, surrounded cells of both human strains and biovar B animal strains. Biovar A field strains revealed capsules as stained by ruthenium red whereas a stock culture strain showed the capsule only when immunostabilized with hyperimmune serum. Starch gel electrophoresis showed all strains to possess adenyl kinase, glutamate dehydrogenases and lactate dehydrogenase; each enzyme migrated uniformly (monomorphic) among the strains and represented an electrotype. However, SDS-PAGE indicated differences in the protein profiles between all of the strains; the most distinctly different was a human isolate (FN 606). Silver staining to detect LPS showed extensive "ladder" patterns among the majority of biovar A strains but not in the animal biovar B strains. Immunoblotting of LPS with a rabbit antiserum prepared against phenol extracted LPS from a biovar A animal isolate (LA 19) suggested marked variability in the LPS antigens among the isolates studied.

Animals↗
PubMed1990

The effect of Mycoplasma bovis on fertilization processes in vitro with bull spermatozoa and zona-free hamster oocytes.

The effect of Mycoplasma bovis (Donetta strain) on the ability of bull spermatozoa to interact with zona pellucida-free hamster oocytes was studied in an in vitro assay. Ejaculates of semen from a fertile Holstein bull were used fresh on the day of collection (unextended semen) as well as diluted with egg yolk-citrate and used the following day (extended semen). The addition of M. bovis to both unextended and extended semen at a mycoplasma to sperm cell ratio of 10:1 significantly reduced sperm penetration rates and the mean number of sperm per penetrated egg. Similarly, the ability of spermatozoa to form pronuclei and the activation of penetrated oocytes were adversely affected by M. bovis. No apparent effect on sperm motility was detected. When M. bovis was added to the oocytes, there was a marked reduction in the sperm penetration rates and fertilization processes suggesting that the organism affects certain oocyte function(s). The results indicate that the presence of M. bovis in semen or in the female reproductive tract may affect fertilization. Moreover, the in vitro assay with hamster oocytes was found to be useful for demonstrating the effects of contaminating microbial agents on bovine fertilization processes.

Animals↗