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Biomedical subjects

G Mendoza

Publications and source records attributed to G Mendoza.

At least 19 recordsLinked to original sources
PubMed1994

Multiple astrocyte transcripts encode nigral trophic factors in rat and human.

The recent discovery of glial cell line-derived neurotrophic factor (GDNF) identified a novel trophin that selectively increases survival of substantia nigra dopaminergic neurons, which degenerate in Parkinson's disease. Our previous studies indicated that GDNF RNA can be amplified from cultured rat nigral type 1 astrocytes and from rat striatum in vivo, implying local as well as target trophic support. The current study establishes the regional pattern of GDNF RNA expression in adult human brain. Reverse transcription-polymerase chain reaction (RT-PCR) analysis revealed the highest expression of GDNF mRNA in the human caudate, with low levels in the putamen and no detectable message in the nigra, suggesting that GDNF is a target-derived factor in humans. We also report the isolation of two additional GDNF-related cDNAs, termed astrocyte-derived trophic factors (ATF), which apparently result from differential RNA processing. Sequence analysis of rat ATF-1 revealed a 78-bp deletion corresponding to a loss of 26 amino acids within the prepro region of the predicted GDNF protein. The RNA processing events responsible for ATF-1 formation in rat brain are conserved in humans; we report the isolation of a full-length human ATF-1 homologue. We identified a second alternative transcript, human ATF-2; the transcript encodes a protein which differs in its first 18 amino acids from the predicted mature GDNF and ATF-1 proteins and shares the terminal 115 residues with the other two forms. To begin assessing the biologic significance of multiple transcript expression we characterized the actions of COS-expressed GDNF and ATF-1 cDNAs.(ABSTRACT TRUNCATED AT 250 WORDS)

Activating Transcription Factor 1↗
PubMed1994

Hepatic myelopathy: a rare complication of portacaval shunt.

Myelopathy is a rare complication of chronic liver disease associated with extensive portal-systemic shunt of blood. Its main clinical feature is a spastic paraparesis without sensory or sphincteric impairment. We describe 3 patients who presented hepatic myelopathy following the performance of a portacaval shunt.

Adult↗
PubMed1992

Frequent semen collection and sperm reserves of the male Angora goat (Capra hircus).

Semen was collected from six mature and sexually rested Angora bucks at one-hour intervals five times a day on each of 5 consecutive days in the breeding season. There was a marked decline in semen volume (P less than 0.001), sperm concentration (P less than 0.05) and number of spermatozoa (P less than 0.001) on consecutive days. Successive ejaculates within days differed only in number of spermatozoa (P less than 0.001). The following year at the beginning of the breeding season, the weights of testes and epididymides and the reserves of spermatozoa in these parts were examined after slaughter of the six bucks. The mean number of spermatozoa in the paired testes, capita, corpora and caudae of the epididymides were (22.8 +/- 1.24) x 10(9), (9.4 +/- 1.19) x 10(9), (3.4 +/- 0.22) x 10(9) and (35.0 +/- 2.21) x 10(9), respectively. Epididymal reserves of spermatozoa were correlated with testicular weight (r = 0.50, P = 0.01) and number of spermatozoa in the testes (r = 0.42, P = 0.07), but not with epididymal weight. The daily production of spermatozoa per animal in the breeding season was estimated to be 4.0-6.4 x 10(9).

Animals↗
PubMed1990

Rabies reference vaccine for use as a regional standard for Latin America and the Caribbean countries.

A candidate rabies reference vaccine of suckling mouse brain (SMB) origin was prepared and standardized at the Pan American Zoonoses Center (PAHO/WHO) and evaluated in a collaborative study involving seven laboratories. On the basis of three different tests, its potency, immunogenicity, and stability were demonstrated to be satisfactory. The vaccine was proposed for consideration of the Latin American and Caribbean countries as a regional standard to determine the potency of SMB vaccines, the most widely used in the Region.

Animals↗
PubMed1984

Two fertile Turner women in a family.

Two fertile women, mother and daughter, both presenting sex chromosomal mosaicism (45,X/46,XX/47,XXX and 45,X/46,Xr(X] are reported. The mechanisms through which a Turner women can eventually be fertile are discussed.

Abortion, Spontaneous↗
PubMed1982

Effect of orally administered cimetidine on histamine- and antigen-induced bronchospasm in subjects with asthma.

Previous studies concerning the effect of cimetidine, a histamine H2 receptor antagonist, on histamine- or antigen-induced bronchoconstriction have yielded conflicting results. Therefore, we examined the effects of cimetidine on sensitivity to both histamine- and antigen-induced bronchospasm in 12 subjects with mild asthma (baseline FEV1 greater than 70% predicted). Bronchial challenges with inhaled histamine or antigen were performed 2 h after a single dose of 300 mg cimetidine or placebo orally administered in a random, double-blind manner on separate days. The provocative concentration of antigen or histamine that produced a 20% decline in FEV1 from the postdiluent control value (PC20) was determined and log transformed. Plasma cimetidine concentrations 2 h after oral administration (mean, 1.5 microgram/ml; range, 0.9 to 2.4 mirograms/ml) were above the minimal concentration required for suppression of gastric acid secretion. No difference was noted in FEV1, specific airway conductance, or partial expiratory flow rates after cimetidine compared with that after placebo, indicating the lack of any bronchospastic effect of cimetidine in the absence of histamine or antigen challenge. However, mean log PC20 of histamine (but not of antigen) was significantly less after cimetidine than after placebo (p less than 0.05), indicating that cimetidine augmented histamine-(but not antigen-) induced bronchospasm. Four of 12 subjects exhibited a significant (greater than or equal to fourfold) decline in PC20 for histamine after cimetidine compared with that after placebo but no subject demonstrated a significant (greater than or equal to tenfold) decline in PC20 of antigen. No relationship was apparent between baseline sensitivity to histamine and cimetidine effect on histamine sensitivity in individual subjects. We conclude that in subjects with mild asthma, cimetidine in the usual recommended orally administered dose can increase sensitivity to bronchospasm induced by histamine but not by antigen. These findings suggest that cimetidine in this dose has a blocking effect on H2 receptors in airway smooth muscle but that this effect is not sufficient to alter the net impact of immunologic release of mediators on the airways.

Adult↗
PubMed1981

Chronic vitamin A intoxication. A multisystem disease that could reach epidemic proportions.

Two patients seen in a six-month period had a diffuse, multisystem disorder characterized by edema of the extremities and face, rash, bone pain and tenderness, symptoms of increased intracranial pressure, and hypercalcemia. Both had been receiving extraordinarily high doses of vitamin A for some time. Serum vitamin A concentrations were markedly elevated, and serum vitamin D concentrations were normal. The history of excessive vitamin administration was only elicited following the detection of hypercalcemia. This is a potential complication of the administration of unregulated food supplements, stressing the need for complete dietary histories in the evaluation of multisystem disorders, with or without hypercalcemia.

Bone and Bones↗