Search PubMed⌕ Search

Biomedical subjects

F Lopez

Publications and source records attributed to F Lopez.

At least 73 records · Page 4Linked to original sources
PubMed1994

Geographic independence of HTLV-I and HTLV-II foci in the Andes highland, the Atlantic coast, and the Orinoco of Colombia.

To clarify the ethnic specificity of human T cell leukemia virus type I (HTLV-I) and type II (HTLV-II) carriers among Colombian native Indians, we investigated the geographic distribution of HTLV-I and HTLV-II seroprevalence among the isolated ethnic groups of Mongoloid origin in the Andes highlands and the Atlantic coast of Colombia. HTLV-I carriers were found in 1.6% (1/62 samples) of Inga, 8.5% (5/59) of Kamsa, and 0% (0/55) of Cumbal Indians who live in the Andes highlands at 3000 m above sea level. On the other hand, HTLV-II carriers were found in 4.1% (5/123) of Wayuu Indians, who live in the Guajira region of the Atlantic coast of Colombia at a distance of 1000 km from the Andes highlands. This ethnic specificity of HTLV-II was similarly observed among Guahibo Indians in the Orinoco. The seroprevalence of HTLV-I and HTLV-II was mutually exclusive among Inga, Kamsa, and Wayuu Indians. These results suggest that HTLV-I and HTLV-II may have evolved among Mongoloid populations and been independently transmitted among two different lineages of Colombian native Indians, Andes highlanders and Atlantic coast lowlanders.

Adolescent↗
PubMed1994

Identification by 2D-page analysis of salt-stress induced proteins in radish (Raphanus sativus).

The response of Raphanus sativus to salinity has been investigated. Salt-responsive proteins were detected by comparative 2D-PAGE analysis. Three polypeptides of 22, 28 and 28.5 kDa were isolated and subjected to microsequencing. The P22 possesses homology with members of the Kunitz family of trypsin inhibitor; the P28.5 is homologous to ascorbate peroxidase of several plant species while P28 did not exhibit significant homology with sequences archived in available databases.

Amino Acid Sequence↗
PubMed1994

Role of Kupffer cells in neutrophil activation and infiltration following total hepatic ischemia and reperfusion.

This study was designed to examine the role of Kupffer cells in polymorphonuclear neutrophils (PMN) activation and infiltration after severe total hepatic ischemia. Male rats pretreated with either normal saline (NS group; n = 58) or gadolinium chloride (7 mg/kg; GC group, n = 57) for 2 days were subjected to 90 min total hepatic ischemia. In addition to 7-day survival rate, aspartate aminotransferase (AST), PMN liver infiltration, plasma myeloperoxidase (MPO), and interleukin-1 (IL-1) levels were serially measured from the end of ischemia to 360 min after reperfusion. Survival rate of the GC group significantly improved to 67% (P < 0.01), whereas that of the NS group remained at 20%. Extremely high AST levels (5,372 +/- 231 IU/liter) were obtained in the NS group, which correlated with the degree of hepatic necrosis. Very high IL-1 (270.3 +/- 91.2 pg/ml) and MPO (1.7 +/- 0.4 U/ml) levels were also seen in the NS group. The GC group significantly inhibited increases in AST, IL-1, and MPO levels as well as PMN infiltration in the liver compared to the NS group (P < 0.05). Our study demonstrated that Kupffer cell activation has an important role in the development of reperfusion injury after total hepatic ischemia through IL-1 release, and PMN activation and infiltration.

Animals↗
PubMed1993

Flow cytometric estimation of poly(A)+ RNA by fluorescent in situ hybridization.

A method for the detection of poly(A)+ RNA in cell suspensions by in situ hybridization and flow cytometry is described. The hybridizing properties of oligothymidylate o(dT) was well preserved after coupling to fluorescein. This fluorescent oligonucleotide was used as a probe to determine the poly(A)+ RNA content of fixed HL60 leukemic cells by flow cytometry. Labeling was considerably reduced by treating the cells with RNAse, and by competitive hybridization with either poly(U) or free poly(A). Labeling was also decreased in a time-dependent fashion by incubating the cells with actinomycin D prior to fixation. This method represents an improvement on the methods measuring total RNA and could be of value in investigations on the effect of drugs on RNA metabolism.

Dactinomycin↗
PubMed1993

Effect of nimodipine, diltiazem and BAY K 8644 on the behavioural and neurochemical changes associated with naloxone-precipitated withdrawal in the rat. A comparison with clonidine.

1. Nimodipine, diltiazem and BAY K 8644 decreased the incidence of wet dog shakes, teeth chattering, grooming and diarrhoea to a similar degree of clonidine. 2. Nimodipine, diltiazem and BAY K 8644 had no effect on changes in the serotonin metabolism induced by naloxone precipitated abstinence syndrome. 3. Clonidine decreased the ratio of serotonin turnover in the brain of morphine-dependent rats. 4. From these experiments it is concluded that nimodipine, diltiazem and BAY K 8644 exert their effects in preventing morphine withdrawal symptoms through a mechanism independent of the serotonergic system.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed1993

[Sexual attitudes and scenarios among students in France, Quebec, and Spain].

Sexual behaviors and attitudes were surveyed among 787, 17-21 years-old students in Lyon (France), Montreal (Quebec) and Salamanque and Madrid (Spain). Near 55% have had intercourse and oral sex in France, while this was the case of almost 80% in Quebec and only about 30% in Spain. Students from France and Quebec were younger at first intercourse, have had more sexual partners, and higher frequencies of intercourse and oral sex than those from Spain. Girls from Quebec have shown higher sexual permissiveness than other girls. Spanish students, particularly girls, consider their parents' sexual attitudes as far less permissive. Religiosity and church attendance seem to still put a strong damper, in Spain, on young people's sexual behaviors.

Adolescent↗
PubMed1993

[Risky sex and contraception in students in France, Quebec and Spain].

In the context of a transational study, 404 sexual active 17-21 years-old students living in Lyon (France), Montreal (Quebec) and Salamanque and Madrid (Spain) have answered a questionnaire dealing with their contraceptive patterns, their perceptions of AIDS and their risky sexual behaviors. Results show that each group uses a different contraceptive strategy. In France and in Quebec those who had their first intercourse before 17 years of age used oral contraceptive rather than the condom. As for AIDS girls from Quebec had a higher index of risky sexual behaviors (CASH) than French, but the opposite was true among boys, while both girls and boys from Spain adopted safer sexual behaviors. Multiple regression analysis shows that the CASH rests on different predictors according to each national context.

Acquired Immunodeficiency Syndrome↗
PubMed1993

Pyelic benign fibroepithelial polyp in childhood: a case report.

Intraluminal masses within the upper urinary tracts are rare, are almost always benign, and most commonly take the form of fibroepithelial polyps within the ureters. Only exceptionally are these lesions found within the renal pelvis and for that reason may cause diagnostic difficulty. We present a new case of fibroepithelial polyp of the renal pelvis treated successfully in our hospital.

Child↗
PubMed1992

Quantitation of resistance of leukemic cells to cytosine arabinoside from BrdUrd/DNA bivariate histograms.

The cytotoxicity of ara-C derives from an inhibition of DNA synthesis after incorporation of ara-CTP into DNA. The rate of DNA synthesis can be determined from the amount of bromodeoxy-uridine (BrdUrd) incorporated into cells after a short exposure to BrdUrd. We developed a computer program to quantify the inhibition of the rate of DNA synthesis by analysis of the distribution of BrdUrd/DNA. Inhibition was evaluated in ara-C-sensitive and resistant cells after incubation with different doses of ara-C. An index of resistance to ara-C (RI) was expressed as the ratio of the amount of BrdUrd incorporated into S phase cells incubated with ara-C to that incorporated in the absence of ara-C. In the ara-C-sensitive and resistant HL60 cells, a linear relationship between RI and log ara-C concentration was observed. Small numbers of slightly resistant cells in mixtures of ara-C-sensitive and resistant cells could be determined using this method, making it suitable for clinical use to test the resistance of leukemic cells to ara-C.

Bromodeoxyuridine↗
PubMed1992

Intercalation of anthracyclines into living cell DNA analyzed by flow cytometry.

Anthracyclines (ANT) are used in the treatment of leukemia and other cancers. These drugs have been shown to intercalate between the strands of DNA. In the present study, we show that the amount of ANT intercalated into DNA can be determined by measuring the fluorescence resonance energy transfer (FRET) between Hoechst 33342 (H33342) and ANT bound to DNA. The transfer efficiency was found to depend on the amount of disposable ANT but was independent of the amount of H33342 bound to DNA over a wide range of H33342 concentrations. The method was adapted for flow cytometric measurement of FRET in whole living cells and was used to evaluate the degree of intercalation of daunorubicin (DAU) and idarubicine (IDA) into DAU-sensitive and DAU-resistant leukemic cell lines. ANT intercalation into DNA was affected by factors which modify the intracytoplasmic concentration of ANT, and it was shown that the action of ANT and the resistance to ANT could not be attributed solely to the intercalative effect of the drugs. The method has advantages over previously described methods and represents a useful complementary tool in studies on the mode of action of ANT and the mechanisms of chemoresistance.

Benzimidazoles↗
PubMed1992

Sexual transmission of human T-lymphotropic virus type I in Peruvian prostitutes.

The epidemiology of HTLV-I infection in female prostitutes was studied in a survey of 395 prostitutes from Callao, Peru (the port city of Lima), 72 prostitutes from Iquitos, Peru (another port city on the Amazon River), and 510 prenatal clinic patients from Lima. Prostitutes reported a mean of 8.8 years (range, 1-39 years) of active prostitution and a mean of 205 sexual contacts during the month prior to the study. The percentage of prostitutes with HTLV-I antibody (21.8%) was significantly higher than patients attending a prenatal clinic (3.1%; P less than .0001). The prevalence of HTLV-I antibody increased steadily with age in prostitutes, but no age trend was noted in prenatal patients. By multiple logistic regression analysis, an independent association was found between HTLV-I seropositivity and a history of prostitution in Callao, age, and positive syphilis serology when all 977 study subjects were evaluated. When prostitutes alone were analyzed, the number of years of exposure as a practicing prostitute was associated with HTLV-I seropositivity after controlling for age. These data indicate a greatly increased risk of HTLV-I infection in prostitutes in Callao, Peru, and suggest an association between sexual activity and HTLV-I transmission.

Adolescent↗
PubMed1992

Effects of chronic treatment with ethanol and withdrawal of ethanol on levels of dopamine, 3,4-dihydroxyphenylacetic acid and homovanillic acid in the striatum of the rat. Influence of benzodiazepines, barbiturate and somatostatin.

Administration of ethanol for 40 days, at 10.53 +/- 0.25 g/kg/day did not modify levels of dopamine (DA) or 3,4-dihydroxyphenylacetic acid (DOPAC) in the striatum of the rat; however, the concentration of homovanillic acid (HVA) and the ratio of turnover were increased in a statistically significant way (P < 0.05). Twenty-four hours after withdrawal of ethanol appears as the central time of the ethanol-induced abstinence syndrome, showing noticeable decreases in levels of DA (P < 0.05) and DOPAC (P < 0.05), with respect to control and chronically ethanol-treated groups. The concentrations of DA, DOPAC and HVA and ratio of turnover values showed a tendency to return to control normal levels of 48 hr after ethanol withdrawal, although the differences still showed statistical significance (P < 0.05). The intraperitoneal injection of saline, the water soluble benzodiazepine midazolam, the barbiturate thiopental and somatostatin, in single doses, resulted in a noticeable increase in levels of DA, DOPAC and HVA and ratio of turnover values. The intraperitoneal injection of midazolam produced statistically significant decreases in levels of DOPAC and ratio of turnover values (P < 0.01) in rats 48 hr after withdrawal of ethanol, with respect to control and chronically ethanol-treated animals, in contrast to the absence of changes produced when injecting thiopental or somatostatin.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1992

The activation antigen CD69 is selectively expressed on CD8+ endomyocardium infiltrating T lymphocytes in human rejecting heart allografts.

We analyzed the presence of T-cell subsets (CD4/CD8) and the activation markers CD25 and CD69 in the cellular infiltrates of endomyocardium biopsies taken from transplanted human hearts. The results indicate that CD25 was present within specimens mainly infiltrated by CD4+ cells. In contrast, CD69 was found in infiltrated biopsies by CD8+ cells, as determined by single immunofluorescence. Double immunoenzymatic staining was used to investigate the cellular distribution of the activation markers studied in some representative cases. Thus, CD25 was found on both CD4+ and CD8+ cells while CD69 molecule was selectively expressed on CD8+ T-cell subset. These results suggest that CD69 is a surface molecule relevant to the CD8+ cell-mediated graft rejection events of allografted human hearts.

Antigens, CD↗
PubMed1992

Chronic low-dose alprazolam augments gamma-aminobutyric acid(A) receptor function.

After acute administration of low doses, alprazolam displays unusual behavioral and neurochemical characteristics. To determine whether chronic low-dose alprazolam has unique effects, we treated mice for 1-14 days with alprazolam 0.2 mg/kg per day and evaluated open-field activity, benzodiazepine receptor binding, t-butylbicyclophosphorothionate binding, and muscimol-stimulated chloride uptake. Open-field activity in treated mice was similar to that of control mice at each timepoint during alprazolam administration. Similarly, benzodiazepine receptor binding in vivo was unchanged in five brain regions. Benzodiazepine receptor binding in vivo was unchanged in five brain regions. Benzodiazepine binding in vitro in the cortex was unaffected by alprazolam treatment, as was t-butylbicyclophosphorothionate binding in the cortex. However, muscimol-stimulated chloride uptake was increased after 2 and 4 days of alprazolam compared with results after 1, 7, and 14 days. These results are consistent with prior reports of unusual effects of low-dose alprazolam and extend these findings to chronic administration.

Alprazolam↗