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M L Bravo

Publications and source records attributed to M L Bravo.

At least 19 recordsLinked to original sources
PubMed2005

Mutation rates at Y chromosome specific microsatellites.

A collaborative work was carried out by the Spanish and Portuguese ISFG Working Group (GEP-ISFG) to estimate Y-STR mutation rates. Seventeen Y chromosome STR loci (DYS19, DYS385, DYS389I and II, DYS390, DYS391, DYS392, DYS393, DYS437, DYS438, DYS439, DYS460, DYS461, DYS635 [GATA C4], GATA H4, and GATA A10) were analyzed in a sample of 3,026 father/son pairs. Among 27,029 allele transfers, 54 mutations were observed, with an overall mutation rate across the 17 loci of 1.998 x 10(-3) (95% CI, 1.501 x 10(-3) to 2.606 x 10(-3)). With just one exception, all of the mutations were single-step, and they were observed only once per gametogenesis. Repeat gains were more frequent than losses, longer alleles were found to be more mutable, and the mutation rate seemed to increase with the father's age. Hum Mutat 26(6), 520-528, 2005. (c) 2005 Wiley-Liss, Inc.

Age Factors↗
PubMed2001

Autosomal STR genetic variation in negroid Chocó and Bogotá populations.

Genetic data for eight autosomal STRs were obtained from two different population samples from Colombia: the European Mestizo population of Bogotá and the African descent population of the Chocó region. The STRs were analysed in a multiplex system that includes the STR markers CSF1PO, TPOX, TH01, VWA, D13S317, D7S820, D16S539 and D5S818. Separation of the fragments and fluorescent detection was carried out in an ABI 310 DNA sequencer and the typing was made by comparison with sequenced allelic ladders. Exact tests were used for testing linkage between the loci and for Hardy-Weinberg equilibrium. Significant differences were found between both populations for all the loci.

Alleles↗
PubMed2000

Autosomal, mtDNA, and Y-chromosome diversity in Amerinds: pre- and post-Columbian patterns of gene flow in South America.

To evaluate sex-specific differences in gene flow between Native American populations from South America and between those populations and recent immigrants to the New World, we examined the genetic diversity at uni- and biparental genetic markers of five Native American populations from Colombia and in published surveys from native South Americans. The Colombian populations were typed for five polymorphisms in mtDNA, five restriction sites in the beta-globin gene cluster, the DQA1 gene, and nine autosomal microsatellites. Elsewhere, we published results for seven Y-chromosome microsatellites in the same populations. Autosomal polymorphisms showed a mean G(ST) of 6.8%, in agreement with extensive classical marker studies of South American populations. MtDNA and Y-chromosome markers resulted in G(ST) values of 0.18 and 0.165, respectively. When only Y chromosomes of confirmed Amerind origin were used in the calculations (as defined by the presence of allele T at locus DYS199), G(ST) increased to 0.22. G(ST) values calculated from published data for other South American natives were 0.3 and 0.29 for mtDNA and Amerind Y chromosomes, respectively. The concordance of these estimates does not support an important difference in migration rates between the sexes throughout the history of South Amerinds. Admixture analysis of the Colombian populations suggests an asymmetric pattern of mating involving mostly immigrant men and native women.

Africa↗
PubMed1999

Multiple sclerosis: association to HLA DQalpha in a tropical population.

Studies performed in subtropical populations have found significant association between the phenotype multiple sclerosis (MS) and the major histocompatibility complex (MHC). We present the results of a case-control study conducted on a tropical population (Antioquia, Colombia) in order to detect a possible association between MS and HLA DQalpha (HLA DQA1*) alleles. Forty chromosomes belonging to MS patients were compared to two sets of controls (40 and 910 chromosomes, respectively). The HLA DQA1*0101 and DQA1*0102 alleles were found in a significantly higher proportion among the cases than among the controls, whereas the HLA DQA1*0103 allele was found in a significantly lower proportion of the cases. These results suggest that the association of HLA DQA1*0101, DQA1*0102 and DQA1*0103 to the MS phenotype found in Caucasian subtropical populations remains in individuals with MS inhabiting the tropics. This finding could mean that the major genetic component associated to the MHC in subtropical populations is the same in the tropics.

Adult↗
PubMed1998

Increased prevalence of cysticercosis and taeniasis among professional fried pork vendors and the general population of a village in the Peruvian highlands. Cysticercosis Working Group in Peru.

Two different populations in Saylla, a Peruvian village near Cusco, known for chicharrones, a local pork dish, were surveyed by serology and stool examination to determine the prevalence and epidemiologic characteristics of Taenia solium infection. Group I (n=43), the chicharroneros, were members of families professionally devoted to the making and selling of chicharrones, and Group II (n=102) was a sample of the general population of the same village. Unlike people in Group I, general villagers only occasionally prepare or sell this food product, and then only to their neighbors or relatives. The prevalence of taeniasis was extremely high (8.6%) for the chicharroneros and 3% for the general villagers. Seroprevalence for cysticercosis by immunoblot was similarly high in both groups (23.3% and 23.8%, respectively). Being female, older than 30, and having daily contact with pork were factors strongly associated with a positive serologic result for cysticercosis in the chicharroneros, whereas males were more frequently seropositive in the general villagers group. Antibody reaction to more antigen bands in immunoblots and neurologic symptoms were more common among the chicharroneros. Also, in the general villagers group, seroprevalence increased with each exposure factor, ranging from 9.4% in individuals who did not raise pigs to 50% in the small subgroup that raised pigs, butchered their own animals, sold pork, and sold chicharrones, suggesting that these activities are related to increased risk for tapeworm or larval infection.

Adolescent↗
PubMed1997

Cytoprotective activity in the gastric mucosa of rats exposed to carbon tetrachloride-induced liver injury.

The present study was undertaken to evaluate the cytoprotective activity in the gastric mucosa of rats subjected to CCl4-induced liver injury. Response of gastric mucosa to absolute ethanol insult or acid (pylorus ligation) after CCl4 challenge was analyzed. Intraperitoneal administration of CCl4 increased plasma AST and ALT, but liver protein and glycogen levels were decreased; in addition, gastric acid secretion was significantly increased with respect to control animals (1541 +/- 266 vs. 629 +/- 25 mu eq H+; p < 0.001). Microscopical gastric erosions were observed in 3/10 animals after CCl4 challenge. Pylorus-ligated as well as CCl4-challenged rats developed increased susceptibility to gastric lesions, compared to control (lesion indices: 4.6 +/- 0.20 vs 2.8 +/- 0.13; p < 0.05), while showing increased resistance to absolute ethanol-induced gastric damage (30.4 +/- 11.2 vs 89.7 +/- 9.7 mm, p < 0.01). PGE2 levels in the gastric mucosa were not influenced by exposure to CCl4. Ultrastructural studies revealed the presence of continuous ethanol-resistant and apparently more adherent layer of mucus in CCl4-challenged animals. Morphological evaluation revealed an increase in Alcian blue-stained mucus. A dual condition of enhanced sensitivity to HCl with increased tolerance to ethanol was observed in gastric mucosa of CCl4-treated animals. These observations could be explained by the amount and/or composition of protective mucus layer in the gastric mucosa.

Animals↗
PubMed1997

[Paternity analysis: experience in Colombia].

BACKGROUND: Cases of dubious paternity may be resolved analyzing appropriate genetic markers in them. AIM: To report the experience of a Colombian University in resolving cases of dubious paternity. SUBJECTS AND METHODS: Fourteen serologic and electrophoretic genetic markers, that had a high probability of exclusion were analyzed in 349 cases of uncertain paternity. RESULTS: In 50 cases, paternity was excluded and in 34, paternity was attributed with a probability over 0.99. In 85 cases, the paternity index was between 19 and 100, that classifies paternity as probable and in 179 cases, the analysis was inconclusive. CONCLUSIONS: These genetic markers may be useful in the first approach to a paternity in investigation.

Colombia↗
PubMed1996

Polymorphisms and phyletic relationships of the Paisa community from Antioquia (Colombia).

The allelic frequencies of 14 polymorphic loci were obtained for the Paisa community (Antioquia, Colombia) and compared with those of Caucasoids, Negroids and Amerindians as an approach to better understand its ancestral origin. Data pertaining to Caucasoids included Basques, Spaniards and Jews, historically assumed to be the ancestors of Paisas. These comparisons suggested that the Paisa community is a Caucasoid group with very low Amerindian or Negroid contributions. Spaniards or Basques and, to a lesser extent, Sephardims seem to have been their most probable ancestors.

Adolescent↗
PubMed1995

Rh--plasma iron binding capacity association. New evidence.

The relationship between Rh phenotypes and the total iron binding capacity (TIBC) of plasma was studied in a sample from Medellín, Colombia. In a previous report from Santiago, Chile, children carrying the C Rh specificity had a higher level of TIBC than those having the specificity. The same association was found in young people from Medellín.

Chile↗
PubMed1994

Gastrotoxic activity and inhibitory effects on gastric mucosal PGE2 production with different non-steroidal anti-inflammatory drugs: modifications induced by pretreatment with zinc acexamate.

Gastrotoxic activities of different non-steroidal anti-inflammatory drugs (NSAIDs) (diclofenac, indomethacin, ketoprofen, naproxen and piroxicam) administered per os were compared with their ability to inhibit gastric prostaglandin E2 (PGE2) synthesis in the rat. In a parallel study, effects of pretreatment with zinc acexamate (ZAC) were also assessed. NSAIDs invariably caused gastric mucosal damage and a decrease of PGE2 levels. A good correlation between the decrease of PGE2 levels and the index of gastric lesion (r = 0.41; p < 0.021) was observed when results obtained with the different NSAIDs were pooled. ZAC pretreatment significantly decreased the overall severity of lesions induced by NSAIDs. However, no correlation between gastric lesion index and depletion of PGE2 gastric levels was observed after treatment with ZAC (r = 0.012; p < 0.948). These data corroborate the hypothesis that preservation of the capability to synthesize endogenous PGs is of critical importance in the maintenance of gastric mucosal integrity. The gastroprotective action observed with ZAC involves alternative mechanisms other than modification of PGE2 levels.

Aminocaproates↗
PubMed1992

Morphological study of gastric lesions developing in the rat under several damaging conditions: modifications induced by pretreatment with zinc acexamate.

Lesions developing in the gastric mucosa of the rat after exposure to different gastric damaging agents (100 mg/kg aspirin, and 70% or 100% ethanol) were assessed by scanning electron microscopy. The severity of the lesions was quantified according to morphological criteria. Modifications in the severity of these lesions induced by pretreatment with zinc acexamate were also analyzed. The scanning electron microscope revealed that with the exception of absolute ethanol, which caused distinctive morphological features, lesions found under the different experimental agents shared a common pattern of progression. Ultrastructural lesions on surface epithelial cells preceded further alterations of parietal cells. After the integrity of the epithelial cells was lost, detachment of the parietal cells occurred, probably, through peptic digestion of the connections between cells and their extracellular matrices. Pretreatment of animals with zinc acexamate increased the presence of mucus on the gastric surface and significantly prevented the progression of lesions towards the severest stages. Ultrastructural damage of surface epithelial cells was not influenced by this treatment, but detachment of damaged cells was clearly diminished. These data confirm the protective effect of zinc acexamate against gastric aggressions. Moreover, our studies confirm the notion that mucus secretion and maintenance of continuity on the gastric lumen by surface epithelial cells is of critical importance in preventing the gastric damage induced in these experimental models.

Aminocaproates↗
PubMed1991

Experimental reactivation of chronic gastric lesions exposed to different aggressive conditions.

Experimental reactivation of chronic gastric lesions induced by acetic acid injection to the rat stomach was produced after exposure of the animals to different secondary damaging conditions. On day 18 after the initial injury, animals (n = 100) were distributed in five groups. One of them was used as control and the remainder were subjected to absolute ethanol, stress, pyloric ligation or aspirin. Measurements of gastric acid secretion were performed. Pyloric ligation resulted in the maximal rate of acid secretion. Computerized morphometric analysis of the gastric injuries showed a significant association (70%, p less than 0.01) of hemorrhagic lesions with the primary site of chronic injury in animals subjected to pyloric ligation. No significant association was observed after absolute ethanol (30%), aspirin (30%) or stress (35%). The presence of hemorrhage associated with the original gastric lesions was more dependent on the disorganization of the lamina propria and proliferation of chief cells in the margins of the mucosal scar than on the severity of extent of the chronic lesions. These results indicate that local conditions at the level of gastric mucosa together with an increased presence of acid in the gastric lumen provide favorable conditions for the reactivation of primary chronic lesions in the rat.

Acetates↗
PubMed1990

Arthritis mutilans, tumoral calcinosis, Raynaud's phenomenon and Sjögren's syndrome.

We report a female patient who over 25 years developed a progressive deforming arthropathy involving both hands without anatomical or functional abnormalities of other joints. Raynaud's phenomenon, lung fibrosis and Sjögren's syndrome. She had multiple soft tissue and periarticular calcification particularly evident in the lower extremities, shoulders, hands, fingers and back.

Adult↗
PubMed1990

Effect of zinc acexamate and ranitidine on chronic gastric lesions in the rat.

Using the rat as an experimental model we have studied the healing of chronic gastric lesions and the modifications of these lesions by antiulcer agents. Gastric injuries were induced by submucosal injection of 0.05 ml of 5% acetic acid. Placebo, ranitidine (RNT) or zinc acexamate (ZAC) were administered orally. The evolution of gastric injuries was macro- and microscopically evaluated at 6, 12 and 21 days after acetic acid injection. The administration of either RNT (30 mg/kg) or ZAC (200 mg/kg) was followed by a marked improvement of the healing process with respect to control groups. The size of experimental ulcers at 21 days was 3.1 +/- 0.8 mm2 for the control group, 1.8 +/- 1.1 mm2 for RNT-treated animals and 0.3 +/- 0.6 mm2 for ZAC-treated rats (p less than 0.05, vs. control). A similar tendency was observed when lesions were microscopically analyzed. Indices of microscopical lesions (0-6) at 21 days were 3.8 +/- 0.8 for the control group, 3.0 +/- 0.8 for rats receiving RNT and 2.3 +/- 0.4 for rats receiving ZAC (p less than 0.05, vs. control). The statistical analysis of the distribution of microscopical indices of lesions showed significant differences in favour of ZAC at days 6 (p less than 0.01) and 21 (p less than 0.05). Our study indicates that the evolution of gastric damage induced by acid acetic injection was consistently better in rats treated with ZAC than in those receiving RNT. Data obtained in our experiments suggest that the blockade of H2 receptors does not guarantee the optimal healing of chronic gastric lesions induced in rats.

Acetates↗
PubMed1988

Development of a simple embedding procedure allowing immunocytochemical localization at the ultrastructural level.

Immunobed solution A is a water-soluble acrylic compound recently developed for immunocytochemical localization at the light microscopic level. In this study, we combined it with methyl methacrylate (MMA) to achieve sufficient hardness to obtain ultra-thin sections. Samples of platelets were dehydrated and embedded in the water-soluble acrylic mixture (WSAM). The embedding process was carried out at 4 degrees C and final polymerization was induced with either chemical (benzoyl peroxide) or physical (UV light) catalysts. Tubulin was localized at the ultrastructural level in sections embedded according to these two methods. Results were compared with those obtained in platelets processed in Lowicryl. Dehydration and embedding with the WSAM yielded a preservation of antigenicity similar to that obtained in Lowicryl. The new procedure benefits from the low temperature achieved during polymerization, providing good ultrastructural morphology and immunolocalization of protein antigens with the simplicity of a routine embedding procedure for light microscopy.

Acrylates↗
PubMed1988

Evaluation of cutaneous absorption and safety of idoxuridine after topical administration.

The absorption of a preparation of the antiviral drug 5-iodo-2'-deoxyuridine (idoxuridine or IDU] has been assessed in rats. A 40% w/v solution of 3H-IDU in dimethyl sulfoxide (DMSO) was topically applied to rats; cutaneous absorption was determined by morphometric evaluation of autoradiographic preparations of the skin. Passage of the drug to the bloodstream was followed using radioisotopic techniques. In addition, the potential irritative action of the same preparation of IDU was investigated in a more suitable animal model. A predictive guinea pig sensitization study was performed according to the Magnusson and Kligman method. 3H-IDU was detected in the epidermis of the rat 60 min after local application. However, it was not possible to determine noticeable levels of the radiolabelled drug in the circulating blood. Experiments on guinea pigs showed slight transient erythematous responses in three animals of the test group following first challenge, and in one animal of the test group and one of the control group, following the second challenge. The overall results of the sensitization test were negative. These results give experimental support for the safety of the IDU preparation studied.

Animals↗