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Biomedical subjects

L Torres

Publications and source records attributed to L Torres.

At least 37 records · Page 2Linked to original sources
PubMed2001

[Knowledge about sexuality and sex behavior in university students with visual impairment: need of educational materials].

The objective of this study was to identify the knowledge about sexuality (including STD/HIV/AIDS), the sexual practices more frequents and sexuality education sources in a group of students with visual impairments. A self administered questionnaire was utilized in 50 students with visual impairment. Descriptive statistics were utilized. Seventy six percent (76.0%) of the participants presented a high knowledge about sexuality and 22.0% presented moderated knowledge. The no penetrative sexual practice more frequent was corporal caress (82.0%) and the penetrative was penis-vagina (74.0%). The source of sexuality education most common was the conferences (83.9%). Although, in general, the knowledge about sexuality was high, there are "gaps" in them. There is the need to develop educational materials adapted to the needs of the studied population.

Adult↗
PubMed2000

[Resistance of Mycobacterium tuberculosis in Zaragoza, Spain (1993-1997) and related factors].

BACKGROUND: To know the frequency of resistance of Mycobacterium tuberculosis in a general hospital and the related factors. PATIENTS AND METHOD: Transversal study of the sensitivity of Mycobacterium tuberculosis in the Hospital Miguel Servet (Zaragoza, Spain) between 1993-1997; the proportions method was used to study the susceptibility. Statistical analysis of conventional tests and significance level at p < 0.05 were performed. RESULTS: Four hundred and twenty height patients with culture-positive to Mycobacterium tuberculosis were studied; 136 (31.8%) were HIV+, 121 (28.3%) were HIV and in 171 (39.9%) this situation was unknown. In 47 patients (10.9%) the strains isolated were resistant at least to one drug. Primary resistance was 5.9% (22 patients) and acquired resistance was 42.4% (25 patients). Primary resistance in HIV+ patients was 9. 2% and in HIV patients was 7.5%; acquired resistance in HIV+ patients was greater than in HIV patients (51.8% vs 42.8%). When we compared the resistances between both HIV+ and HIV patients we did not find significant differences. Twenty isolates (4.7%) were resistant to more than one drug and 10 (2.3%) were resistant to at least isoniazid and rifampin. The risk factors for acquired resistance were alcohol (odds ratio [OR] = 2.65; 95% CI, 1.24-5.65), drugs users (OR = 2.33; 95% CI, 1.05-5.17), previous episodes of tuberculosis (OR = 109.40; 95% CI, 15.02-796.43) and homeless (OR = 3.75; 95% CI, 1.26-11.17); we did not find significant differences between the different risk factors according to primary resistance. CONCLUSIONS: On one study, the resistance of M. tuberculosis is similar to other described in Spain. We haven't found significant differences between both seropositive and seronegative patients. The risk factors for acquired resistance were alcoholism, drug users, previous episodes of tuberculosis and homeless.

Adult↗
PubMed2000

Vitamin A deficiency causes oxidative damage to liver mitochondria in rats.

Mitochondrial damage in rat liver induced by chronic vitamin A-deficiency was studied using three different groups of rats: (i) control rats, (ii) rats fed a vitamin A-free diet until 50 d after birth and (iii) vitamin A-deficient rats re-fed a control diet for 30 d. No statistical difference in body weight and food intake was found between control and vitamin A-deficient rats. Liver GSH concentration was similar in both groups. However, in vitamin A-deficient rats, the mitochondrial GSH/GSSG ratio was significantly lower and the levels of malondialdehyde (MDA) and 8-oxo-7, 8-dihydro-2'-deoxyguanosine (oxo8dG) were higher when compared to control rats. These values were partially restored in re-fed rats. The mitochondrial membrane potential of vitamin A-deficient rats was significantly lower than in control rats and returned to normal levels in restored vitamin A rats. Two populations of mitochondria were found in vitamin A-deficient rats according to the composition of membrane lipids. One population showed a similar pattern to the control mitochondria and the second population had a higher membrane lipid content. This report emphasizes the protective role of vitamin A in liver mitochondria under physiological circumstances.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed2000

Prosthetic valve endocarditis caused by Mycoplasma hominis.

Mycoplasma hominis endocarditis is extremely uncommon and difficult to diagnose. Atypical growth characteristics in routine bacterial culture and an inability to demonstrate the organism using Gram staining can lead to a delayed diagnosis of Mycoplasma hominis infections, and the organism is often missed. This report describes a patient with Mycoplasma hominis prosthetic valve endocarditis. The microorganism was recovered from the mitral prosthesis but was missed in blood cultures. This finding suggests that Mycoplasma hominis should be considered in the differential diagnosis of culture-negative endocarditis.

Endocarditis, Bacterial↗
PubMed2000

Reduced mRNA abundance of the main enzymes involved in methionine metabolism in human liver cirrhosis and hepatocellular carcinoma.

BACKGROUND/AIMS: It has been known for at least 50 years that alterations in methionine metabolism occur in human liver cirrhosis. However, the molecular basis of this alteration is not completely understood. In order to gain more insight into the mechanisms behind this condition, mRNA levels of methionine adenosyltransferase (MAT1A), glycine methyltransferase (GNMT), methionine synthase (MS), betaine homocysteine methyltransferase (BHMT) and cystathionine beta-synthase (CBS) were examined in 26 cirrhotic livers, five hepatocellular carcinoma (HCC) tissues and ten control livers. METHODS: The expression of the above-mentioned genes was determined by quantitative RT-PCR analysis. Methylation of MAT1A promoter was assessed by methylation-sensitive restriction enzyme digestion of genomic DNA. RESULTS: When compared to normal livers MAT1A, GNMT, BHMT, CBS and MS mRNA contents were significantly reduced in liver cirrhosis. Interestingly, MAT1A promoter was hypermethylated in the cirrhotic liver. HCC tissues also showed decreased mRNA levels of these enzymes. CONCLUSIONS: These findings establish that the abundance of the mRNA of the main genes involved in methionine metabolism is markedly reduced in human cirrhosis and HCC. Hypermethylation of MAT1A promoter could participate in its reduced expression in cirrhosis. These observations help to explain the hypermethioninemia, hyperhomocysteinemia and reduced hepatic glutathione content observed in cirrhosis.

Carcinoma, Hepatocellular↗
PubMed2000

Identification of argininosuccinate lyase as a hypoxia-responsive gene in rat hepatocytes.

BACKGROUND/AIMS: The differential oxygenation of periportal and perivenous hepatocytes has been demonstrated as a major determinant in the zonated expression of certain metabolic pathways in the liver. We have searched for novel genes whose expression could be modulated by hypoxia in cultured rat hepatocytes. METHODS: Primary cultures of rat hepatocytes were incubated under normoxic (21% oxygen) or hypoxic (3% oxygen) conditions for 6 h. Differences in gene expression under both conditions were analyzed using the technique of differential display by means of PCR. RESULTS: We have identified the enzyme argininosuccinate lyase (ASL) as being downregulated by hypoxia. ASL is a cytosolic protein which participates in urea metabolism. ASL expression was time-dependently reduced in hypoxia. Hypoxia modulated the responses of this gene to the two main hormonal signals which induce ASL mRNA: glucocorticoids and cAMP. ASL mRNA levels decreased in response to ATP-reducing agents. CoCl2 mimicked the effect of hypoxia, suggesting the implication of a hemoprotein in this response. Hypoxia did not affect ASL mRNA stability, indicating that this effect occurs at the transcriptional level. CONCLUSIONS: Our observations suggest that differences in oxygen levels across the hepatic parenchyma could participate in the zonated expression of ASL.

Adenosine Triphosphate↗
PubMed2000

Utility of the BACTEC Myco/F lytic medium for the detection of mycobacteria in blood.

This study aims to evaluate the performance of a new vial (Myco/F Lytic) for the detection of mycobacteria from blood specimens. This vial is monitored in the BACTEC 9000 blood culture system. We compared it with the traditional method routinely used in our laboratory, which is a lysis-centrifugation based procedure. Of 275 samples tested in parallel by both methods, 23 from 20 patients grew mycobacteria (18 Mycobacterium avium complex, 4 M. tuberculosis and 1 M. simiae); 11 isolates were recovered using both systems, 12 were isolated with the Myco/F Lytic medium only, and none were isolated using the traditional method only (p < 0.05). Blood was the diagnostic sample for 12 patients with the Myco/F Lytic system and only 7 with the traditional system. The mean time to detection of mycobacteria with Myco/F Lytic medium was 17 days, whereas it was 44 days with the traditional method (p < 0.001). Identification by DNA probes was performed directly from the Myco/F Lytic bottle. Myco/F Lytic is a rapid, simple, safe and highly reliable diagnostic method for the detection of mycobacteria in blood.

Bacteremia↗
PubMed2000

Tourette's syndrome and neurofibromatosis type 1.

The case of an 11-year-old male with clinical features compatible with a diagnosis of Tourette's syndrome and neurofibromatosis type 1 is reported. Magnetic resonance imaging revealed bilateral pallidal hyperintensities, which may be related to the tic disorder.

Child↗
PubMed2000

Liver-specific methionine adenosyltransferase MAT1A gene expression is associated with a specific pattern of promoter methylation and histone acetylation: implications for MAT1A silencing during transformation.

Methionine adenosyltransferase (MAT) is the enzyme that catalyzes the synthesis of S-adenosylmethionine (AdoMet), the main donor of methyl groups in the cell. In mammals MAT is the product of two genes, MAT1A and MAT2A. MAT1A is expressed only in the mature liver whereas fetal hepatocytes, extrahepatic tissues and liver cancer cells express MAT2A. The mechanisms behind the tissue and differentiation state specific MAT1A expression are not known. In the present work we examined MAT1A promoter methylation status by means of methylation sensitive restriction enzyme analysis. Our data indicate that MAT1A promoter is hypomethylated in liver and hypermethylated in kidney and fetal rat hepatocytes, indicating that this modification is tissue specific and developmentally regulated. Immunoprecipitation of mononucleosomes from liver and kidney tissues with antibodies mainly specific to acetylated histone H4 and subsequent Southern blot analysis with a MAT1A promoter probe demonstrated that MAT1A expression is linked to elevated levels of chromatin acetylation. Early changes in MAT1A methylation are already observed in the precancerous cirrhotic livers from rats, which show reduced MAT1A expression. Human hepatoma cell lines in which MAT1A is not expressed were also hypermethylated at this locus. Finally we demonstrate that MAT1A expression is reactivated in the human hepatoma cell line HepG2 treated with 5-aza-2'-deoxycytidine or the histone deacetylase inhibitor trichostatin, suggesting a role for DNA hypermethylation and histone deacetylation in MAT1A silencing.

Acetylation↗
PubMed2000

[Effects of environmental tobacco smoke on lower respiratory system of children under 5 years of age].

OBJECTIVE: To determine the effects of second-hand smoke in the respiratory system of children under 5 years old. METHODS: A cross sectional study of a total of 1,104 children under 5 years old. Information about respiratory symptoms and illness, family history of respiratory diseases, smoking habits of household members and housing conditions were assessed by home interviews with the children's parents. RESULTS: We studied 546 boys and 558 girls. Among 611 children exposed to second-hand smoke, 82% had respiratory problems (odds ratio = 1.64; 95% confidence interval: 1.21-2.20). Children whose parents were smokers at the time of the survey were more likely to experience wheezing than children of nonsmoking parents (odds ratio = 1.66; 95% confidence interval: 1.21-2.27), shortness of breath (odds ratio = 1.91; 95% confidence interval: 1. 36-2.67), morning and day time or night coughs (odds ratio = 1.58; 95% confidence interval: 1.09-2.28). The odds ratio for asthma, bronchitis and pneumonia was greater for children exposed to second-hand smoke (odds ratio = 1.60; 95% confidence interval: 1. 11-2.31). CONCLUSIONS: Maternal smoking, paternal smoking, family history of respiratory diseases, and housing conditions are considered risk factors for respiratory diseases in children.

Age Distribution↗
PubMed1999

Induction of TIMP-1 expression in rat hepatic stellate cells and hepatocytes: a new role for homocysteine in liver fibrosis.

Elevated plasma levels of homocysteine have been shown to interfere with normal cell function in a variety of tissues and organs, such as the vascular wall and the liver. However, the molecular mechanisms behind homocysteine effects are not completely understood. In order to better characterize the cellular effects of homocysteine, we have searched for changes in gene expression induced by this amino acid. Our results show that homocysteine is able to induce the expression and synthesis of the tissue inhibitor of metalloproteinases-1 (TIMP-1) in a variety of cell types ranging from vascular smooth muscle cells to hepatocytes, HepG2 cells and hepatic stellate cells. In this latter cell type, homocysteine also stimulated alpha 1(I) procollagen mRNA expression. TIMP-1 induction by homocysteine appears to be mediated by its thiol group. Additionally, we demonstrate that homocysteine is able to promote activating protein-1 (AP-1) binding activity, which has been shown to be critical for TIMP-1 induction. Our findings suggest that homocysteine may alter extracellular matrix homeostasis on diverse tissular backgrounds besides the vascular wall. The liver could be considered as another target for such action of homocysteine. Consequently, the elevated plasma levels of this amino acid found in different pathological or nutritional circumstances may cooperate with other agents, such as ethanol, in the onset of liver fibrosis.

Animals↗
PubMed1999

Functional magnetic resonance imaging study of frontal lobe activation during word generation in obsessive-compulsive disorder.

BACKGROUND: Functional imaging studies have demonstrated abnormal patterns of brain activity in obsessive-compulsive disorder, which consistently suggest the alteration of frontal lobe functioning. We performed a brain activation study in obsessive-compulsive disorder using a cognitive task involving the frontal lobes. METHODS: Twenty patients and 20 healthy control subjects were assessed with functional magnetic resonance imaging during a phonologically guided word generation task. The study analysis was based on the comparison of group average time-course functional changes occurring at the site of largest frontal cortex activation during alternating rest and task periods. RESULTS: In terms of relative signal changes, patients showed a significantly greater activation during word generation and a defective suppression of this activation during the following rest period. Both abnormal imaging findings significantly correlated with the severity of the clinical process assessed by the Yale-Brown Obsessive-Compulsive Scale. CONCLUSIONS: The results indicate that functional magnetic resonance imaging during cognitive challenge may be useful to reveal distinctive features of latent brain dysfunction in obsessive-compulsive disorder.

Adolescent↗
PubMed1999

Scant XYqh- testicular cells with normal SRY was enough to differentiate bilateral testes in a 45,X/46,XYqh- patient.

OBJECTIVE: It has been established that in 45,X/46,XY individuals predominance of XY or XO gonadal cells determines gonadal differentiation. However, in some cases there is no concordance between the predominance of XY cells and testis differentiation. Here we describe the SRY findings in a patient bearing a 45,X/46,XYqh- karyotype. STUDY DESIGN: The patient presented two small testes (one with spermatogenesis), a male phenotype, and a predominant 45,X karyotype in leukocytes and gonadal cells. PCRs of SRY, ZFY and Yqh were performed on DNA from leukocytes and from left gonadal tissue. SRY-PCR products were purified and sequenced. RESULTS: A normal SRY sequence was found in both tissues. CONCLUSIONS: Despite the predominance of 45,X cells in gonads, some patients in whom SRY is normal can develop testes, probably due to the presence of alternative mechanisms involved in testicular differentiation; however, further gonadal development could be impaired.

Animals↗
PubMed1999

An atypical contiguous gene syndrome: molecular studies in a family with X-linked Kallmann's syndrome and X-linked ichthyosis.

BACKGROUND AND OBJECTIVE: Kallmann's syndrome (KS) is characterized by hypogonadotrophic hypogonadism in association with anosmia or hyposmia. This entity can be associated with X-linked ichthyosis (XLI) in a contiguous gene syndrome. Genetic defects have been demonstrated on the Xp22.3 region explaining the presence of one or both entities in affected individuals. In this report we describe the molecular findings in four patients, pertaining to a three generation family, with KS which was associated with XLI in two of them. MEASUREMENTS: Enzymatic activity of steroid sulphatase was measured in leucocytes. Polymerase chain reaction of the 14 exons of the Kallmann gene (KAL) and of the 5' and 3' extremes of the steroid sulphatase gene was performed in genomic DNA. PCR products of the 14 exons of the KAL gene were purified and sequenced. RESULTS: Absence of steroid sulphatase activity and a complete deletion of the STS gene were demonstrated in both patients with XLI. In all subjects, the 14 KAL gene exons amplified in a normal fashion; no mutation was documented after sequencing all exons. CONCLUSIONS: Although it has been proposed recently that the X-linked form of the disease accounts for the minority of patients with Kallman's syndrome, the pedigree chart of this family demonstrates this inheritance pattern. Various possibilities are mentioned in order to explain the absence of mutation in the KAL gene. The coexistence, in this family, of Kallman's syndrome individuals and patients with Kallman's syndrome and X-linked ichthyosis is discussed.

Adult↗
PubMed1999

Elevated expression of liver gamma-cystathionase is required for the maintenance of lactation in rats.

Liver gamma-cystathionase activity increases in rats during lactation; its inhibition due to propargylglycine is followed by a significant decrease in lactation. This is reversible by N-acetylcysteine administration. To study the role of liver gamma-cystathionase and the intertissue flux of glutathione during lactation, we used lactating and virgin rats fed liquid diets. Virgin rats were divided into two groups as follows: one group was fed daily a diet containing the same amount of protein that was consumed the previous day by lactating rats (high protein diet-fed rats); the other virgin group was fed the normal liquid diet (control). The expression and activity of liver gamma-cystathionase were significantly greater in lactating rats and in high protein diet-fed virgin rats compared with control rats. The total glutathione [reduced glutathione (GSH) + oxidized glutathione (GSSG)] released per gram of liver did not differ in lactating rats or in high protein diet-fed rats, but it was significantly higher in these two groups than in control virgin rats. Liver size and the GSH + GSSG released by total liver were significantly higher in lactating rats than in high protein diet-fed virgin rats, and this difference was similar to the amount of glutathione taken up by the mammary gland (454.2 +/- 36.0 nmol/min). The uptake of total glutathione by the lactating mammary gland was much higher than the uptakes of free L-cysteine and L-cystine, which were negligible. These data suggest that the intertissue flux of glutathione is an important mechanism of L-cysteine delivery to the lactating mammary gland, which lacks gamma-cystathionase activity. This emphasizes the physiologic importance of the increased expression and activity of liver gamma-cystathionase during lactation.

Acetylcysteine↗