Biomedical subjects

M M Garcia

Publications and source records attributed to M M Garcia.

At least 37 records · Page 2Linked to original sources

PubMed1998

Adherence of Bilophila wadsworthia to cultured human embryonic intestinal cells.

Adherence of Bilophila wadsworthia to the cultured human embryonic intestinal cell line, Intestine 407 (Int 407), varied among the strains tested from strongly adherent (76-100% cells positive for one or more adherent bacteria) to non- or weakly adherent (0-25% positive cells). Although negative staining revealed that infrequent cells of an adherent strain, WAL 9077, the adherent type-strain, WAL 7959, and a non-adherent strain, WAL 8448, expressed loosely associated fimbrial structures, a role for these structures in adhesion could not be confirmed with either scanning or thin-section electron micrography. Ruthenium red staining of thin-section preparations and subsequent electron microscopy failed to reveal an extensive extracellular polysaccharide layer. SDS-PAGE analysis of crude outer membrane fractions of WAL 9077 and WAL 8448 demonstrated clear differences in their major and minor outer membrane protein components. Thus, we postulate that the adherence of B. wadsworthia to Int 407 cells is mediated by an outer membrane or cell wall component.

Journal Article↗

PubMed1998

Drugs of abuse and immediate-early genes in the forebrain.

A diverse array of chemical agents have been self administered by humans to alter the psychological state. Such drugs of abuse include both stimulants and depressants of the central nervous system. However, some commonalties must underlie the neurobiological actions of these drugs, since the desire to take the drugs often crosses from one drug to another. Studies have emphasized a role of the ventral striatum, especially the nucleus accumbens, in the actions of all drugs of abuse, although more recent studies have implicated larger regions of the forebrain. Induction of immediate-early genes has been studied extensively as a marker for activation of neurons in the central nervous system. In this review, we survey the literature reporting activation of immediate-early gene expression in the forebrain, in response to administration of drugs of abuse. All drugs of abuse activate immediate-early gene expression in the striatum, although each drug induces a particular neuroanatomical signature of activation. Most drugs of abuse activate immediate-early gene expression in several additional forebrain regions, including portions of the extended amygdala, cerebral cortex, lateral septum, and midline/intralaminar thalamic nuclei, although regional variations are found depending on the particular drug administered. Common neuropharmacological mechanisms responsible for activation of immediate-early gene expression in the forebrain involve dopaminergic and glutamatergic systems. Speculations on the biological significance and clinical relevance of immediate-early gene expression in response to drugs of abuse are presented.

Amphetamines↗

PubMed1998

A two focal plane method for digital quantification of nuclear immunoreactivity in large brain areas using NIH-image software.

In principle, digital acquisition of cell-count data from serially-sectioned immunocytochemical material is a straightforward enterprise. First, a serial brain section is magnified by use of a microscope interfaced to a computer. Then, using appropriate hardware and software, a digital image is captured, and cellular profiles of interest are segmented from background objects according to mean grayscale intensity and pixel area. Ideally, the cells of interest would be uniformly distinguishable from other objects or areas of the image, with respect to grayscale intensity and size. However, due to non-uniformity in background staining of neuropil, immunocytochemical material often departs markedly from this ideal situation. As a consequence, determining grayscale intensity and cell size cutoff values which separate cells of interest from background becomes laborious and arbitrary. This problem can be diminished by increasing the magnification of the digitized image, which increases the figure-ground resolution of the image. However, high-magnification images make tissue navigation difficult and require that multiple images be captured. This paper describes a two focal plane procedure for obtaining cell counts from nuclear-stained immunocytochemistry material. This procedure allows the capturing and cell counting of relatively low-magnification images with high digital figure-ground resolution.

Animals↗

PubMed1997

Protein kinase C in central auditory pathways of the rat.

Protein kinase C is an important intracellular signaling molecule. Many of its ten isoforms are highly expressed in brain, and protein kinase C has been implicated in the regulation of the activity of receptors of several major neurotransmitters, including glutamate, acetylcholine, glycine, and gamma-aminobutyric acid. These neurotransmitters and their receptors are present in central auditory pathways, suggesting their role in auditory signal processing. Although they may be important modulators of the function of these neurotransmitter receptors, the distribution of protein kinase C isoforms in central auditory systems has not been well characterized. By using immunocytochemistry with specific antibodies, we studied the distribution of immunoreactivity of four isoforms of protein kinase C, betaI, betaII, gamma, and gamma, in central auditory systems of rat brain. Each of these protein kinase C isoforms was found to have a unique distribution in the auditory brainstem and cortex, supporting a role for these isoforms of protein kinase C in different aspects of auditory sensory processing.

Animals↗

PubMed1997

Protein kinase C in central vestibular, cerebellar, and precerebellar pathways of the rat.

The protein kinase C family of enzymes is composed of at least ten different isoforms that display a variety of distinct biochemical specificities. Many of these isoforms are highly expressed in brain, and some show regional specificity in their distribution, suggesting that they may serve specific functions. By using immunocytochemistry to localize the betaI, betaII, gamma, or delta isoforms of protein kinase C in the central vestibular system of the adult rat, we found the vestibular ganglion and its peripheral and central processes of the eighth nerve to be heavily labeled with protein kinase C betaI immunoreactivity. Labeled axons and terminals were also found in all four vestibular nuclei. Some neurons of the vestibular ganglion were weakly stained with the antibody to protein kinase C betaII, as were scattered axons in the eighth nerve, and scattered axons and terminals were found in all four vestibular nuclei among weakly labeled neurons. A few axons in the vestibular portion of the eighth nerve were labeled with protein kinase C gamma immunoreactivity, and neurons of the spinal, lateral, and superior vestibular nuclei were heavily decorated with synapses, presumably derived from Purkinje neurons, which were also strongly immunoreactive. Neurons of the medial vestibular nucleus were not as heavily innervated. With the antibody to protein kinase C delta, we found scattered, weakly immunoreactive neurons in the vestibular portion of the eighth nerve. Myelinated fiber bundles of the spinal vestibular nucleus contained moderate numbers of labeled axons, and the other vestibular nuclei were well innervated by protein kinase C delta axons and terminals. Most of these probably derive from Purkinje cells, which were labeled in longitudinal bands interspersed with bands of labeled basket cells. These data suggest that particular protein kinase C isoforms play specific roles in vestibular and cerebellar function.

Animals↗

PubMed1997

Characterization of monoclonal antibodies for the rapid detection of foodborne campylobacters.

The specificity of 97 monoclonal antibodies (MAbs) to the Campylobacter jejuni Lior serogroup 6 reference strain was assessed using an indirect enzyme linked immunosorbent assay (ELISA). Four MAbs, M316, M337, M357 and M637, reacted with whole cells of the C. jejuni, C. coli and C. lari reference strains of the 20 most common Lior serogroups and 25 recent C. jejuni and C. coli isolates, and did not react with most of the 42 other Campylobacter and non-Campylobacter spp. tested. Immunoblot analysis revealed that MAbs M337 and M357 reacted with a protein component with molecular mass of approximately 62 kiloDaltons (kDa) while M316 and M637 reacted with protein components of approximately 92 and 31 kDa, respectively. The detection limit of M357 in an indirect ELISA was 10(5) colony forming units. These four highly specific MAbs may be useful reagents of an immunoassay for the rapid detection of thermophilic campylobacters in foods and clinical samples.

Antibodies, Monoclonal↗

PubMed1997

Substantia innominata: a notion which impedes clinical-anatomical correlations in neuropsychiatric disorders.

Comparative neuroanatomical investigations in primates and non-primates have helped disentangle the anatomy of the basal forebrain region known as the substantia innominata. The most striking aspect of this region is its subdivision into two major parts. This reflects the fundamental organizational scheme for this portion of the forebrain. According to this scheme, two major subcortical telencephalic structures, i.e. the striatopallidal complex and extended amygdala, form large diagonally oriented bands. The rostroventral extension of the pallidum accounts for a large part of the rostral subcommissural substantia innominata, while the sublenticular substantia innominata is primarily occupied by elements of the extended amygdala. Also dispersed across this region is the basal nucleus of Meynert, which is part of a more or less continuous collection of cholinergic and non-cholinergic corticopetal and thalamopetal cells, which stretches from the septum diagonal band rostrally to the caudal globus pallidus. The basal nucleus of Meynert is especially prominent in the primate, where it is sometimes inappropriately applied as a synonym for the substantia innominata, thereby tacitly ignoring the remaining components. In most mammals, the extended amygdala presents itself as a ring of neurons encircling the internal capsule and basal ganglia. The extended amygdala may be further subdivided, i.e. into the central extended amygdala (related to the central amygdaloid nucleus) and the medial extended amygdala (related to the medial amygdaloid nucleus), which generally form separate corridors both in the sublenticular region and along the supracapsular course of the stria terminalis. The extended amygdala is directly continuous with the caudomedial shell of the accumbens, and to some extent appears to merge with it. Together the accumbens shell and extended amygdala form an extensive forebrain continuum, which establishes specific neuronal circuits with the medial prefrontal-orbitofrontal cortex and medial temporal lobe. This continuum is particularly characterized by a prominent system of long intrinsic association fibers, and a variety of highly differentiated downstream projections to the hypothalamus and brainstem. The various components of the extended amygdala, together with the shell of the accumbens, are ideally structured to generate endocrine, autonomic and somatomotor aspects of emotional and motivational states. Behavioral observations support this proposition and demonstrate the relevance of these structures to a variety of functions, ranging from the various elements of the reproductive cycle to drug-seeking behavior. The neurochemical and connectional features common to the accumbens shell and the extended amygdala are especially relevant to understanding the etiology and treatment of neuropsychiatric disorders. This is discussed in general terms, and also in specific relation to the neurodevelopmental theory of schizophrenia and to the neurosurgical treatment of neuropsychiatric disorders.

Animals↗

PubMed1997

DNA fingerprinting of Campylobacter fetus using cloned constructs of ribosomal RNA and surface array protein genes.

DNA fragments coding for the ribosomal RNA and the surface array proteins of Campylobacter fetus have been cloned from a genomic library constructed in Escherichia coli. They were used in the molecular characterization of C. fetus (subsp. fetus; subsp. venerealis) strains by restriction fragment length polymorphism (RFLP) method. Ribotyping results showed that all strains of the two subspecies can be classified under one ribogroup implying very close relatedness. The sapA gene DNA marker, however, discriminated all the strains regardless of the subspecies when chromosomal DNA was restricted with HindIII, HaeIII, XbaI or EcoRV. These results illustrate that the sapA probe is potentially useful in fingerprinting C. fetus strains and in determining the relationships of strains for epidemiological purposes.

Animals↗

PubMed1997

Humoral immune responses in patients with acute Schistosoma mansoni infection who were followed up for two years after treatment.

Eighteen patients with acute Schistosoma mansoni infection were followed up for 2 years after treatment with praziquantel or oxamniquine. Cure rates, clinical features, abdominal ultrasonographic findings, and specific humoral responses were determined at 2-, 6-, and 24-month follow-ups. Fourteen patients (77.8%) were considered parasitologically cured. Levels of IgA antibody to soluble egg antigen (SEA) and IgM antibody to keyhole limpet hemocyanin (KLH) became negative or decreased to the cutoff level for chronic infection 2 months after treatment, while levels of IgG antibody to KLH declined between 12 and 24 months after treatment. Levels of IgM and IgG antibodies to saline worm adult protein as well as IgM and IgG antibodies to SEA remained positive during the follow-up period. Discrete lymph node enlargement and hepatomegaly were still present in six of the eight cured children 2 years after treatment, while complete regression was observed in adults. In our group of patients, in addition to presenting with more intense clinical manifestations, children were cured less often and had slower abatement of symptomatology after treatment than adults.

Abdomen↗

PubMed1997

Specific detection and confirmation of Campylobacter jejuni by DNA hybridization and PCR.

Conventional detection and confirmation methods for Campylobacter jejuni are lengthy and tedious. A rapid hybridization protocol in which a 1,475-bp chromogen-labelled DNA probe (pDT1720) and Campylobacter strains filtered and grown on 0.22-micron-pore-size hydrophobic grid membrane filters (HGMFs) are used was developed. Among the environmental and clinical isolates of C. jejuni, Campylobacter coli, Campylobacter jejuni subsp. doylei, Campylobacter lari, and Arcobacter nitrofigilis and a panel of 310 unrelated bacterial strains tested, only C. jejuni and C. jejuni subsp. doylei isolates hybridized with the probe under stringent conditions. The specificity of the probe was confirmed when the protocol was applied to spiked skim milk and chicken rinse samples. Based on the nucleotide sequence of pDT1720, a pair of oligonucleotide primers was designed for PCR amplification of DNA from Campylobacter spp. and other food pathogens grown overnight in selective Mueller-Hinton broth with cefoperazone and growth supplements. All C. jejuni strains tested, including DNase-producing strains and C. jejuni subsp. doylei, produced a specific 402-bp amplicon, as confirmed by restriction and Southern blot analysis. The detection range of the assay was as low as 3 CFU per PCR to as high as 10(5) CFU per PCR for pure cultures. Overnight enrichment of chicken rinse samples spiked initially with as little as approximately 10 CFU/ml produced amplicons after the PCR. No amplicon was detected with any of the other bacterial strains tested or from the chicken background microflora. Since C. jejuni is responsible for 99% of Campylobacter contamination in poultry, PCR and HGMF hybridization were performed on naturally contaminated chicken rinse samples, and the results were compared with the results of conventional cultural isolation on Preston agar. All samples confirmed to be culture positive for C. jejuni were also identified by DNA hybridization and PCR amplification, thus confirming that these DNA-based technologies are suitable alternatives to time-consuming conventional detection methods. DNA hybridization, besides being sensitive, also has the potential to be used in direct enumeration of C. jejuni organisms in chicken samples.

Animals↗

PubMed1997

Disease risks to animal health from artificial insemination with bovine semen.

Two of the major goals of artificial insemination of domesticated animals are to achieve continuous genetic improvement and to prevent or eliminate venereal disease. In comparison with natural service, fewer males are needed to artificially inseminate the same number of females and to produce the same number of offspring. However, there are risks associated with artificial insemination, which has the potential to disseminate genetic defects and also to spread infectious disease nationally and internationally. This paper focuses on the risk of six specific diseases which are transmitted in bull semen and outlines the appropriate measures to prevent these risks.

Animals↗

PubMed1997

Comparative effects of nabumetone, sulindac, and ibuprofen on renal function.

OBJECTIVE: Nonsteroidal antiinflammatory drugs (NSAID) have been associated with hemodynamically mediated acute renal failure. There appear to be differences among NSAID in producing this effect. We compare renal effects of ibuprofen, sulindac, and nabumetone. METHODS: Seventeen women over age 56 receiving hydrochlorothiazide and fosinopril for hypertension who had osteoarthritis requiring NSAID received 3 different NSAID to evaluate potential varying renal effects. In an investigator blinded randomized study, patients received nabumetone, sulindac, or ibuprofen for 1 month with intervening 2 week control periods. After each period renal function was assessed by inulin and para-aminohippurate clearances and urinary prostaglandins were measured. RESULTS: No overall statistical differences among the NSAID were observed. However, there were clinically meaningful differences during ibuprofen therapy: 4 patients developed a clinically significant decrease in renal function; during sulindac therapy one of these also developed a clinically significant decrease in renal function. During nabumetone there were 0 episodes of clinically significant decrease in renal function. Using Gomez equations, glomerular hydrostatic pressure and afferent and efferent arteriolar resistances were estimated. None changed overall during any intervention. However, the 4 patients who developed decreased renal function while taking ibuprofen were analyzed separately. Glomerular hydrostatic pressure decreased 15%; afferent arteriolar resistance increased 85%. These changes were associated with marked decreases in vasodilatory prostaglandins compared to patients receiving ibuprofen who did not develop decreases in renal function. CONCLUSION: There are differences in effect on renal function among NSAID. These can be correlated with specific alterations in suppression of the cyclooxygenase system cascade and related to changes in the hemodynamic control of glomerular filtration.

Anti-Inflammatory Agents, Non-Steroidal↗

PubMed1996

Chronic morphine decreases calbindin D28k immunoreactivity in a subset of cerebellar Purkinje neurons of rat brain.

Calbindin D28k is an intracellular calcium binding protein that is expressed in the cell bodies, nuclei, dendrites, and axons of nearly all Purkinje neurons of the rat cerebellum. Acute morphine administration has been reported to decrease the level of calbindin mRNA in extracts of whole rat cerebellum [75]. Using immunocytochemistry, we studied the effects of chronic morphine administration and morphine abstinence on levels of calbindin in cerebellar Purkinje neurons. Treatment of male rats for 5 days with either morphine injections (10 mg/kg s.c., twice daily) or subcutaneously implanted morphine pellets (75 mg/pellet, once daily) markedly decreased levels of calbindin immunoreactivity in long stretches of Purkinje cell bodies in various folia of cerebellum. After 7 days of abstinence from morphine, the number of calbindin-positive neurons was still significantly decreased, and at 14 days of abstinence, the number of labeled neurons continued to be below that in control rat brain. The effects of morphine in cerebellum were not antagonized by co-administration of the N-methyl-D-aspartate receptor antagonist, MK-801 (0.2 mg/kg, twice daily for 5 days). MK-801 alone also decreased the number of calbindin-positive cells, but in a different pattern from that of morphine. Our findings of decreased calbindin immunoreactivity in Purkinje neurons following chronic morphine administration and abstinence suggest that persistent alterations in intracellular calcium buffering may be associated with opiate tolerance and dependence in cerebellum.

Animals↗

PubMed1996

Electrophoretic and immunoblot analysis of Campylobacter fetus lipopolysaccharides.

Proteinase K-digested cell lysates from 25 Campylobacter fetus subspecies fetus and C. fetus subsp. venerealis strains were examined by SDS-PAGE and immunoblotting. Three SDS-PAGE lipopolysaccharide (LPS) profiles were observed. Two profiles were consistent with those previously reported for serogroup A and serogroup B and AB isolates and were distinguished by the relative mobility of bands in the O-chain region and by a strong reaction on immunoblots with homologous antisera. The third profile was similar but had faster migrating O-chain bands. Immunoblot reactions using homologous and heterologous adsorbed antisera showed that the O-antigen of the C. fetus subsp. fetus reference strain and other profile 2-type LPS strains was distinct from the O-antigens of strains with profile 1- or profile 3-type LPS. O-antigens of strains with profile 1- and profile 3-type LPS had shared epitopes. One strain had core components but no detectable O-antigens. Common core LPS antigens appear to be present in all strains and antibodies to common core LPS epitopes may be useful reagents for rapid detection of C. fetus.

Animals↗

PubMed1996

[Longitudinal study of the mother and child population in an urban region of southern Brazil, 1993: methodological aspects and preliminary results].

All babies born in the hospitals of the city of Pelotas, Brazil, in 1982 were studied soon after delivery and followed up prospectively during the first years of their lives. In 1993, this study was repeated with a similar methodology, with the aim of assessing eventual changes in the level of maternal and child health. All five maternity hospitals in the city were visited daily and the 5,304 babies born included in the study. They were weighed and measured, and their gestational age was assessed using the Dubowitz method. Their mothers were examined and interviewed regarding a large number of risk factors. The mortality of these children was studied through the surveillance of all hospitals, cemeteries and death registries, and all hospital admissions were also recorded. Two nested case-control studies were carried out to assess risk factors for mortality and hospital morbidity. A systematic sample of 655 children were examined at home at one and three months of age, and these infants, as well as another sample of 805 children including all low-birthweight babies were also examined at the ages of six and twelve months. Their psychomotor development was also assessed. Losses to follow-up were only 6.6% at twelve months. Relative to the 1982 indicators, perinatal mortality fell by about 30% and infant mortality by almost 50%. The median duration of breastfeeding increased from 3.1 to 4.0 months. On the other hand, there was little change in the prevalences of low birthweight or of length for age at twelve months. The article that refers this abstract describes the methodology of the study and forthcoming publications will present detailed results.

Birth Weight↗

PubMed1995

Charting of Jun family member proteins in the rat forebrain and midbrain: immunocytochemical evidence for a new Jun-related antigen.

Immunocytochemistry was used to localize members of the Jun family of immediate-early genes in the forebrain and midbrain of non-stimulated male rats. Antibodies against specific peptide sequences of c-Jun (Ab-1 and Ab-2 from Oncogene Science) and against expressed proteins of JunB and JunD (both from Dr. R. Bravo) revealed widespread and unique distributions for each of these antigens. Charts were made of the distribution of each antigen, and extensive comparisons were made of previous results obtained using in situ hybridization to localize mRNAs for c-jun, junB and junD. Our results indicate a generally favorable comparison between immunoreactivity and distribution of mRNAs for JunB and JunD, but in the case of c-Jun, immunoreactivity and mRNA were comparable only with the Ab-1 antibody. Indeed, the immunocytochemical distribution of the antigen recognized by the c-Jun Ab-2 antibody was distinctly different from that of the other Jun proteins or mRNAs in the rat brain. This antibody (Ab-2) recognized a nuclear protein found extensively in the caudate-putamen, nucleus accumbens, layer II of the olfactory tubercle, the central nucleus of the amygdala, and the lateral division of the bed nucleus of the stria terminalis. Scattered labeled nuclei were found in a few other forebrain structures. Within the caudate-putamen, immunoreactivity was restricted to the matrix compartment, as determined by immunostaining of adjacent sections with the matrix-marker calbindin D28k. Western blots of caudate-putamen demonstrated that this antibody recognized a protein doublet of molecular masses approximately 37 and 34 kDa, distinct from the molecular masses of c-Jun, JunB and JunD. This unique neuroanatomical distribution and molecular mass suggests that this antibody recognizes a previously undescribed Jun-related antigen.

Animals↗

PubMed1995

Alterations in immediate-early gene proteins in the rat forebrain induced by acute morphine injection.

Injection of morphine (10 mg/kg) induced a complex immediate-early gene response in the rat forebrain, as detected with immunocytochemistry. The c-Fos protein was induced consistently in the dorsomedial caudate-putamen, the nucleus accumbens, and in midline and intralaminar nuclei of the thalamus. In some rats induction was also seen in the parietal and insular cortex and in lateral regions of the caudate-putamen. Induction was detectable, although weak, at 30 min, was maximal at 2 h, and was undetectable 3 h after injection. JunB was induced in the same regions of the caudate-putamen as found for c-Fos, but was not induced in the nucleus accumbens or thalamus. In the caudate-putamen, JunB induction was still present 3 h after injection. A considerably smaller induction of c-Jun was noted in the dorsomedial caudate-putamen and in deep neocortex. Expression of JunD was inhibited in intralaminar and midline thalamic nuclei. Increases in numbers of cells immunoreactive for a Jun-related antigen (Jra) were found in the caudate-putamen and nucleus accumbens. These results indicate a complex immediate-early gene response to acute morphine, suggesting that morphine activates or inhibits specific neurons and circuits in the forebrain.

Animals↗

PubMed1995

A detection assay for Campylobacter fetus in bovine semen by restriction analysis of PCR amplified DNA.

A rapid screening assay for Campylobacter fetus in bull semen was developed using the polymerase chain reaction (PCR) and restriction endonuclease analysis (REA) to complement isolation by culture. An oligonucleotide primer pair (C1/C2) from the hypervariable region of 16S rRNA of C. fetus was used to amplify a 362 base pair fragment by PCR. The PCR/REA assay, which is completed in 10 hours, detected as few as three C. fetus subsp. venerealis cells in experimentally infected raw bull semen and in semen diluted with milk or egg yolk Tris (EYT). All the strains tested, of both subspecies of C. fetus, were amplified, as were some other Campylobacter species. Restricting the amplified products by AluI differentiated C. fetus from the other organisms. There was no visible product generated by PCR from C. sputorum subsp. bubulus, a saprophytic organism found in the prepuce of bulls, or from seven other species of bacteria found in semen. A modification of the PCR assay, using another primer pair (C3/C2) and two temperature PCR cycling conditions, increased the probability of detecting C. fetus subsp. venerealis. PCR amplification followed by REA could be used to screen bovine semen rapidly for C. fetus. In most cases, sequencing of C1/C2 PCR generated products would be preferable for distinguishing between the two subspecies of C. fetus.

Animals↗