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Biomedical subjects

J Segovia

Publications and source records attributed to J Segovia.

At least 73 records · Page 4Linked to original sources
PubMed1993

[Etiologic diagnosis of pneumonia in HIV-AIDS patients. Usefulness of fibrobronchoscopy].

AIM: to assess the usefulness of fiberoptic bronchoscopy in the etiologic diagnosis of pulmonary infiltrates in patients with AIDS. PATIENTS AND METHODS: in 25 patients with AIDS and pneumonia, 31 fiberoptic bronchoscopies with bronchoalveolar lavage were performed; in 11 occasions, a transbronchial biopsy was also performed. RESULTS: in 24 of the 31 procedures (77%) an etiologic diagnosis was made. There were 7 false negative results; in two of these patients, a repeated examination allowed an etiologic diagnosis. The etiologies of the infiltrates were pyogenic bacteria in 14 cases. Pneumocystis carinii in 9, mycobacteria in 3, cytomegalovirus in one and a lymphocytic interstitial pneumonia in one. In 5 patients, the association of two or more etiological agents was observed. Except one case, all patients had a good response to specific treatments. There were no complications attributed to the bronchoscopic procedure. CONCLUSIONS: fiberoptic bronchoscopy and bronchoalveolar lavage are safe and effective procedures for the etiologic diagnosis of pulmonary infiltrates in patients with AIDS.

AIDS-Related Opportunistic Infections↗
PubMed1991

Striatal glutamic acid decarboxylase immunoreactivity is increased after dopaminergic deafferentation: densitometric analysis.

Several lines of evidence suggest that dopamine exerts a chronic inhibitory action on GABAergic cells in the striatum, and striatal glutamic acid decarboxylase (GAD) mRNA levels are increased after ipsilateral dopaminergic denervation. In the present study we have used GAD immunocytochemistry to assess whether dopaminergic denervation results in an increase in GAD protein synthesis. In three 6-hydroxydopamine-lesioned animals, there was a perceptible increase in the density of GAD-immunoreactive (ir)staining on the side ipsilateral to the lesion. Computer-assisted densitometric analysis showed a significant increase in GAD-ir staining in the ipsilateral striatum compared to the contralateral (control) side. These data suggest that removal of striatal dopaminergic innervation results in an increase in the amount of immunoreactive GAD, the rate limiting enzyme in the synthesis of GABA.

Afferent Pathways↗
PubMed1991

Transplants of fetal substantia nigra regulate glutamic acid decarboxylase gene expression in host striatal neurons.

Lesions of the dopaminergic innervation to the striatum result in increased activity of glutamic acid decarboxylase (GAD) and increased GAD mRNA in striatal GABAergic neurons. Here we show that solid transplants of dopamine-containing fetal mesencephalic tissue placed adjacent to the striatum can completely reverse the elevation of GAD mRNA in the striatum of adult rats with complete lesions of the nigrostriatal dopamine projections. The ability of the fetal transplants to re-establish control over gene expression in host target neurons indicates that there is a significant transneuronal influence of the transplanted neurons. Furthermore, striatal GAD mRNA levels appear to be a good marker of the functional impact of dopamine-producing transplants.

Animals↗
PubMed1991

Health status and health practices--Alameda and beyond.

Using the population of St John's, Newfoundland, we did a constructive replication of previous studies testing the association between health practices and health status. A telephone questionnaire was applied to all adults in a probabilistic sample of households (3300 subjects, 85% response rate). Several health practices and preventive behaviours indexes were developed and tested. An additive index of six practices (breakfast, sleeping, drinking, smoking, weight and exercise) using the Alameda County definitions, and an additive score of five practices (excluding breakfast and with revised definitions for smoking, drinking and exercise) were analysed using log-linear models; there was association between the indexes and self-assessed health status when controlling for sex, age and education, with the exception of the six-practice index in males. The association between these two indexes and several variables and constructs of health status showed that the best relationships were with self-assessed health status and with a construct including variables measuring subjective health.

Adult↗
PubMed1990

Parallel increases in striatal glutamic acid decarboxylase activity and mRNA levels in rats with lesions of the nigrostriatal pathway.

Adult male rats were lesioned with 6-hydroxydopamine in order to destroy the nigrostriatal dopaminergic projections. In rats with such a lesion, we found a parallel increase in glutamic acid decarboxylase (GAD) activity and GAD mRNA in the striatum ipsilateral to the lesion at 4 weeks and 4 months after the lesion. These observations support the proposal that nigral dopaminergic neurons exert a tonic inhibitory control over the striatal GABAergic neurons. Our observations also suggest that the dopaminergic neurons can inhibit gene expression in striatal GABAergic neurons and that the enhanced striatal GAD activity following lesions of the dopaminergic projections is due to 'de novo' synthesis of the enzyme.

Animals↗
PubMed1989

Effect of dopaminergic denervation and transplant-derived reinnervation on a marker of striatal GABAergic function.

Solid grafts of dopamine-containing fetal mesencephalon were placed adjacent to the striatum of rats with 6-hydroxydopamine lesions of ascending dopaminergic projections. These grafts resulted in a significant, although partial, reversal of the lesion-induced increase in striatal glutamic acid decarboxylase (GAD) when measured 3-4 months after the lesion. These results suggest that the grafted neurons can partly restore inhibitory control over striatal GABA neurons. In the same rats, the grafts partially reversed apomorphine-induced turning although amphetamine-induced turning was nearly abolished. It is likely that both apomorphine-induced behavior and striatal GAD activity reflect the sustained chronic influence of the graft on target neurons in striatum.

Amphetamine↗
PubMed1989

Tissue levels and in vivo release of tachykinins and GABA in striatum and substantia nigra of rat brain after unilateral striatal dopamine denervation.

Brain tissue levels and in vivo release of substance P (SP) and neurokinin A (NKA) and GABA were measured bilaterally in striatum and substantia nigra of the rat, after a unilateral 6-hydroxydopamine lesion of the nigro-striatal dopamine pathway. Sham injected animals served as controls. The dopamine denervation decreased the tissue levels of SP in striatum (-38%) ipsilateral to the lesion and in substantia nigra both ipsi- (-54%) and contralateral (-38%) to the lesion. NKA was not significantly changed in the striatum, but decreased (like SP) in the substantia nigra both ipsi- (-50%) and contralateral (-40%) to the lesion. GABA tissue levels increased in the denervated striatum (+20%) and remained unchanged in substantia nigra at both sides. The extracellular levels of SP, NKA and GABA were measured with microdialysis in vivo at basal conditions and during stimulation with potassium administered locally via the microdialysis probe. The stimulated release of SP and NKA in the substantia nigra ipsilateral to the lesion was compared to in sham operated animals reduced with 39% and 64%, respectively, while no change in SP or NKA release was detected in the striatum. The basal release of GABA in the striatum was increased with 296% and with 76% during stimulation in the dopamine denervated striatum, while no change in GABA basal or stimulated release was detected in the substantia nigra. We suggest that the increased GABA release in the dopamine denervated striatum may be due to a decreased dopamine mediated inhibition of local GABA neurons.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

An empirical analysis of the dimensions of health status measures.

The objective of this study is to verify empirically the existence of separate dimensions in the overall concept of health status by analyzing 10 variables included in a questionnaire that was applied to all adults in a simple random sample of households in St John's, Newfoundland. The response rate was 85% for a total of 3300 subjects. These data were analyzed by frequencies and by associations with sex, age and education. Nonparametric correlation, factor and cluster analyses on variables were used to verify if health status had identifiable dimensions. All these methods produced similar results showing five distinct factors. The first factor is composed of variables related to disease (disability/chronic conditions/worry about health); the second, to happiness (happiness/emotional); the third, to subjective appraisal of health (physical condition/comparative level of energy/self-rated health status). Finally, the fourth and fifth factors were single variables; restriction of normal activities and social contacts. An interesting finding was that self-rated health status was distributed with almost equal weight in both the first and third factors. A validation of the 10 variables and the 5 factors was undertaken by studying their association with health care utilization. Two measures of utilization were used; number of physicians' visits in a year and number of hospital days in a 4-year period. Number of chronic conditions, disability and self-rated health status were associated with both measures of utilization; factor 1 was the only summary construct showing association with utilization. This paper demonstrates that self-rated health status is valid as a single measure of overall health status in this sample, being associated with both disease and subjective assessment components.

Adult↗
PubMed1989

Hippocampal membranes contain a neurotrophic activity that stimulates cholinergic properties of fetal rat septal neurons cultured under serum-free conditions.

Primary cultures of fetal rat septal neurons were used to identify a membrane-associated cholinergic neurotrophic activity. Under serum-free culture conditions, approximately 98% of the septal cells are neurons, and approximately 6% of the neurons are cholinergic as determined immunocytochemically. Crude membranes prepared from rat hippocampal homogenates stimulate choline acetyltransferase (ChAT) activity in treated septal neurons. The membrane-associated trophic activity is apparent at lower protein concentrations than activity present in the soluble fraction and is unevenly distributed in various brain regions; it is highest in hippocampus and striatum and negligible in cerebellum. Membrane trophic activity is developmentally regulated, is heat and trypsin sensitive, and increases the rate of expression of ChAT in septal neurons. Upon gel filtration chromatography of a high-salt membrane extract, trophic activity elutes as a broad peak in the 500 kilodalton (kD) molecular mass range. Stimulation of septal neuronal ChAT activity by either crude membranes or partially purified preparations is not inhibited by antibodies against nerve growth factor (NGF), and its maximal activity is additive to maximally active doses of NGF. The results indicate that hippocampal membranes contain cholinergic neurotrophic activity which may be important for the development of septal cholinergic neurons.

Aging↗
PubMed1988

Pneumoconiosis in iron ore surface mining in Labrador.

A cross-sectional survey of the work force at an iron ore surface mine and beneficiation plant in Labrador identified cases with a radiologic diagnosis compatible with simple pneumoconiosis by the International Labour Organization (ILO) classification (1980). Their distribution by ILO categories 1, 2, and 3, after excluding those with confounding diagnoses for pneumoconiosis, was 30, 10, and 2 cases, respectively. ILO category was related to age, duration of current employment, and cumulative respirable dust and quartz levels, as well as to decrement in ventilatory function.

Adult↗