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Biomedical subjects

B López

Publications and source records attributed to B López.

At least 37 records · Page 2Linked to original sources
PubMed2000

Mechanisms of increased susceptibility to angiotensin II-induced apoptosis in ventricular cardiomyocytes of spontaneously hypertensive rats.

Previous findings have shown that hypotensive doses of losartan prevent the excess of apoptosis present in the hypertrophied left ventricle of adult spontaneously hypertensive rats (SHR). This study was designed to determine whether angiotensin II facilitates apoptosis in cardiomyocytes of adult SHR. Primary cultures of ventricular cardiomyocytes from 30-week-old normotensive Wistar-Kyoto rats (WKY) and SHR with left ventricular hypertrophy were exposed to 10(-)(9) mol/L angiotensin II for 24 hours. Apoptotic cells were assessed by terminal deoxynucleotidyl transferase assay and confirmed by Annexin V detection. The expression of Bax-alpha, Bcl-2, p53, and caspase-3 proteins was assessed by Western blot assays. The expression of BAX gene was assessed by Northern blot. Angiotensin II increased (P<0.01) cardiomyocyte apoptosis, and this effect was higher (P<0.001) in SHR cells than in WKY cells. Whereas losartan (10(-7) mol/L) blocked the apoptotic effect of the octapeptide in cells from the two strains of rats, PD123319 (10(-7) mol/L) inhibited angiotensin II-mediated apoptosis only in SHR cells. Angiotensin II stimulated (P<0.01) Bax-alpha protein, and this effect was higher (P<0.01) in SHR cells than in WKY cells. Angiotensin II did not modify Bcl-2, p53, and BAX mRNA in cells from the two strains of rats. Angiotensin II induced a similar increase (P<0.05) in the ratio caspase-3/procaspase-3 (an index of caspase-3 activation) in cardiomyocytes from the two strains of rats. The present in vitro results indicate that SHR cardiomyocytes exhibit enhanced susceptibility to angiotensin II-induced apoptosis. Ligand binding to angiotensin II type 1 and type 2 receptors leading to changes in posttranscriptional processing of Bax-alpha and accumulation of this proapoptotic protein may be involved in the abnormal response of SHR cardiomyocytes. These data support a role for angiotensin II in apoptosis observed in the left ventricle of these rats.

Angiotensin II↗
PubMed2000

[Biochemical diagnosis of hypertensive myocardial fibrosis].

A substantial increase in fibrillar collagen has been observed in the left cardiac ventricle of animals and humans with arterial hypertension. Hypertensive myocardial fibrosis is the result of both increased collagen types I and III due to the fact that its synthesis by fibroblasts and myofibroblasts is stimulated and its extracellular collagen degradation unchanged or decreased extracellular collagen degradation. Hemodynamic and non-hemodynamic factors may be involved in the disequilibrium between collagen synthesis and degradation that occurs in hypertension. As shown experimentally and clinically, an exaggerated rise in fibrillar collagen content promotes abnormalities of cardiac function, contributes to the decrease in coronary reserve and facilitates alterations in the electrical activity of the left ventricle. Although microscopic examination of cardiac biopsies is the most reliable method for documenting and measuring myocardial fibrosis, the development of non-invasive methods to indicate the presence of myocardial fibrosis in hypertensive patients would be useful. We have therefore applied a biochemical method based on the measurement of serum peptides derived from the tissue formation when synthesized and degradation of fibrillar collagens to monitor the turnover of these molecules in rats with spontaneous hypertension and patients with essential hypertension.

Endomyocardial Fibrosis↗
PubMed1999

Epidemiological study of Streptococcus pneumoniae carriers in healthy primary-school children.

To obtain information on the Streptococcus pneumoniae carrier state in Spanish children, 332 healthy 6-year-old children from nine primary schools in northern Spain were screened. Thirty-six percent of the children had positive cultures yielding 128 strains. Seventy-one strains belonged to 14 serogroup/serotypes, the most frequent being 19, 23, 3, 24 and 11. Fifty-seven strains were nontypeable. The identification of strains with equivocal results was confirmed at species level by means of hybridisation with a specific probe, pneumolysin-mediated agglutination and a pathogenicity test in mice. Sixty-four percent of strains showed resistance to penicillin, 22% of these also being resistant to cefotaxime. More than 40% of the strains were resistant to trimethoprim-sulfamethoxazole, tetracycline and erythromycin. Twenty percent of the erythromycin-resistant strains were susceptible to clindamycin. Two strains were resistant to rifampicin and one strain was resistant to ofloxacin. All strains were susceptible to vancomycin. Previous antibiotic administration and having siblings under the age of 2 years correlated with the carriage of pneumococcus. There was no correlation with the carriage of antibiotic-resistant strains, or a record of previous infections, previous hospital admissions or having relatives with chronic respiratory disease.

Animals↗
PubMed1999

Changes in polyamines and ethylene during the development and ripening of eggplant fruits (Solanum melongena).

The levels of free polyamines in the endocarpium of eggplants (Solanum melongena) cv. Black Nite were studied during fruit growth and ripening. Other parameters such as weight and volume variation, respiratory intensity, ethylene production, and sugar content were determined. The polyamines found were putrescine and spermidine, with a higher amount of the former. No spermine, agmatine, or cadaverine were found during the development and ripening period of eggplant. At the beginning of fruit development, the levels of putrescine and spermidine observed were 1.67 nmol/g of fresh tissue. Putrescine levels peaked at 17.4 nmol/g of fresh tissue on the ninth day after petal fall, decreasing later to the initial levels. No significant changes in spermidine were observed during the growth period of the fruit. Beginning 9 days after petal fall, there was a rapid increase in fruit weight and volume, which coincided with the maximum content of free polyamines. At the same growth stage, total sugar content was maximum. Ethylene production decreased rapidly from 14.23 to 1.5 microL/kg.h and remained low during the whole growth period.

Ethylenes↗
PubMed1999

Comparative analysis of quantification of viral load in patients infected with hepatitis C virus: quantiplex HCV RNA assay and amplicor monitor assay.

OBJECTIVE: two standardized techniques, Quantiplex HCV RNA 2.0 (bDNA) and Amplicor Monitor, were evaluated for the quantification of hepatitis C virus (HCV) load. Our objectives were: 1) to determine the relationship between viral load and genotype, and 2) to evaluate viral load in serial serum samples and in patients with normal or slightly elevated liver enzyme values in an area with a high prevalence of genotype 1. RESULTS: the viral loads detected with the two methods correlated significantly (r = 0.7, p < 0.0001), but viral load was smaller with the Monitor than with the Quantiplex assay, and was independent of genotype. The Monitor/Quantiplex ratio was lower in patients with a non-1 genotype than in patients with genotype 1b. Virological characteristics were similar in patients with normal or slightly elevated enzyme levels and in patients with elevated enzyme values. Neither method showed a relationship between viral load and age, sex, duration of the infection, mode of transmission, or histological activity index. CONCLUSION: viral load was not dependent on genotype. Measurement of viral load in a single serum sample adequately reflected the viral load measured in several serum samples from patients with chronic HCV infection. Patients with normal liver enzyme levels are not good candidates, in virological terms, for treatment with interferon.

Adolescent↗
PubMed1998

Plants used in Guatemala for the treatment of protozoal infections. I. Screening of activity to bacteria, fungi and American trypanosomes of 13 native plants.

Extracts were prepared from 13 native plants used for the treatment of protozoal infections. Activity against bacteria and fungi was demonstrated by dilution procedures; Trypanosoma cruzi was evaluated in vitro against epimastigote and trypomastigotes and in vivo against trypomastigotes. In active extracts, toxicity was evaluated by Artemia salina nauplii, oral acute toxicity (1-5 g/kg) and oral and intraperitoneal subacute toxicity in mice (500 mg/kg). From the plants screened, six showed activity (< or = 2 mg/ml) against bacteria, three against yeasts, five against Microsporum gypseum and five against T. cruzi in vitro and/or in vivo. In vitro and in vivo activity was demonstrated by Neurolaena lobata and Solanum americanum; in vitro or in vivo activity was shown by Acalypha guatemalensis, Petiveria alliacea and Tridax procumbens. Toxicity studies showed that extracts from S. americanum are toxic to A. salina (aqueous, 160 ppm). None showed acute or oral toxicity to mice; S. americanum showed intraperitoneal subacute toxicity.

Animals↗
PubMed1998

Soft salt-mannitol agar-cloxacillin test: a highly specific bedside screening test for detection of colonization with methicillin-resistant Staphylococcus aureus.

The early detection of colonization with methicillin-resistant Staphylococcus aureus (MRSA) of patients in intensive-care units is an essential step in the strategy for preventing MRSA epidemics. In this study, tubes containing soft salt-mannitol agar with cloxacillin (6 microg/ml) (SSMAC) were prepared for inoculation of clinical samples at patients' bedsides by personnel of an intensive-care unit. A total of 1,914 swabs from different sample sites of 81 patients were dipped into SSMAC tubes, and after 24 h of incubation (in an incubator located near the intensive-care unit), an evident color change was considered by the intensive-care-unit personnel to be an MRSA alarm. Sixty-three (3.3%) SSMAC tubes were considered positive for MRSA, 1,827 (95.4%) were considered negative, and 24 (1.2%) were considered intermediate. Compared with values for parallel conventional surveillance cultures for MRSA, excluding tubes with intermediate results, the SSMAC test had a sensitivity of 72.7%, a specificity of 99.2%, a positive predictive value of 76.2%, and a negative predictive value of 99.0%. When intermediate tubes were considered positive, the corresponding values were 75.3, 98.2, 63.2, and 99.0%, respectively. The sensitivity and specificity values of the test to identify MRSA-colonized patients were 89.4 and 100%, respectively. Oropharyngeal and naris specimens were the most reliable samples for MRSA detection. False-negative results were frequent in bronchial aspirates with low (< 10(3) to 10(6) CFU/ml) MRSA counts. False-positive results were mainly due to methicillin-resistant Staphylococcus haemolyticus. The SSMAC tube is a useful, rapid, and inexpensive tool for the early identification of MRSA-colonized patients and, consequently, for the implementation of measures to prevent the spread of MRSA.

Adult↗
PubMed1998

Rapid screening tests for determining in vitro susceptibility of herpes simplex virus clinical isolates.

The susceptibility of human herpes simplex virus (HSV) to acyclovir (ACV) was determined with the use of a single dose of the drug (1 and 2 micrograms of ACV per ml for HSV-1 and HSV-2, respectively) in two rapid assays: a rapid cytopathic effect inhibitory assay (Rapid CIA) and a rapid dye uptake assay (Rapid DUA). These tests allow the simultaneous determination of virus titer and susceptibility to ACV at a determined viral concentration (100 50% tissue culture infective doses and 100 50% dye uptake units). These tests were compared with a conventional susceptibility assay (dye uptake assay) and showed similar results. Indeterminate results with the Rapid CIA appeared in 3 of 30 samples. With the use of both Rapid CIA and Rapid DUA, we were able to determine the susceptibility of 100% of the isolates. The rapid tests, unlike conventional assays, are able to provide susceptibility results within 3 days after the virus has been isolated from a clinical specimen and could thus play a direct role in therapeutic decisions.

Acyclovir↗
PubMed1997

Case-based learning of plans and goal states in medical diagnosis.

We introduce a case-based system, BOLERO, that learns both plans and goal states. The major aim is that of improving the performance of a rule-based diagnosis system by adapting its behavior using the most recent information available about a patient. On the one hand BOLERO gets knowledge from cases in the form of diagnostic plans that are represented as sequences of decision steps. The advantages of this representation include: (1) retrieval and adaptation of parts of plans (steps) appropriate to the current problem state; (2) generation of new plans not previously available in memory; and (3) learning from experience, both from successful or failed plans. On the other hand, since goal states are sets of final diagnosis likelihoods they are not known beforehand, i.e. goal states are not defined and the system has to learn to recognize them. For this reason BOLERO has a case-based method that uses solutions of past cases to recognize a diagnostic state as a goal state of a new planning problem. BOLERO and a rule-based system are integrated into a meta-level architecture in which we emphasize the collaboration of both systems in solving problems. The rule-based system executes the plans generated by BOLERO. As a consequence of the execution of plans, the rule-based system furnishes BOLERO with new information with which BOLERO can generate a new plan to adapt the reasoning process of the rule-based system into correspondence with the recent available data. All the methods have been designed to be useful for medical diagnosis and have been tested in the domain of diagnosing pneumonia.

Artificial Intelligence↗
PubMed1997

[Surgical treatment of diffuse hyperthyroid goiter. Experience at a hospital in Valdivia, Chile].

BACKGROUND: The choice of medical, radiation or surgical therapy for hyperthyroid diffuse goiter is still empirical. AIM: To report a retrospective analysis of the surgical treatment of hyperthyroid goiter in a Regional Hospital in Chile. PATIENTS AND METHODS: The charts of 64 patients, 54 female, aged between 15 and 57 years old, operated between 1985 and 1995 were analyzed. RESULTS: The indication for surgical treatment was failure of medical treatment in 59 patients and a big goiter causing mechanical compression in 3 patients. A subtotal thyroidectomy was done after an abbreviated surgical preparation. The mean weight of the resected glands was 65.9 g. Four patients had transient hypocalcemia and 4 had surgical wound seromas. After a mean follow up of 31 months, 77% of patients remain euthyroid, hyperthyroidism relapsed in 13.1% and 10% became hypothyroid. CONCLUSIONS: Surgical treatment of hyperthyroid goiter is safe but the percentage of hyperfunction relapse is high.

Adolescent↗
PubMed1996

Febrile ulceronecrotic Mucha-Habermann disease: a case report and review of the literature.

A 32-year-old male with febrile ulceronecrotic Mucha-Habermann disease (FUMHD) responsive to methotrexate is reported. This is a severe variant of pityriasis lichenoides et varioliformis acuta characterized by the acute onset of a widespread ulceronecrotic cutaneous eruption together with high fever and systemic involvement. To our knowledge, only 13 patients with FUMHD have been reported to date.

Adult↗
PubMed1994

Lactose maldigestion and milk intolerance: a study in rural and urban Mexico using physiological doses of milk.

Lactose digestion capacity after ingestion of physiological doses of milk and its effect on milk intolerance and consumption were studied in rural and urban populations from three regions of Mexico with different milk intakes. All subjects (n = 926) received two treatments: whole milk (240 mL for children and 360 mL for adults) and the same amount of 90% lactose-hydrolyzed milk; 72% of the subjects also received as a third treatment a water solution containing lactulose (8 g for children and 10 g for adults). Lactose maldigestion determined by a hydrogen breath test was detected in 2 to 43% of subjects (depending on age group) and was higher in subjects from central and southern Mexico than in subjects from northern Mexico (P < 0.01). Only the experience of major symptoms of intolerance affected milk consumption, and these symptoms were present in 0 to 11% of children > 4 y old and in 7 to 17% of the 13- to 60-y-old subjects. No significant differences were found in lactose maldigestion or milk intolerance between rural and urban populations, but milk consumption was higher in urban areas (P < 0.01). Milk consumption in our study was affected primarily by factors not related to the capacity to digest or tolerate the lactose in milk.

Adolescent↗
PubMed1994

[Humoral response to mycobacteria in patients with Crohn disease].

The recent recovery of Mycobacterium paratuberculosis from tissues of patients with Crohn's disease has highlighted the possible etiologic role of this microorganism in the disease. However, the immunological evidence generated by various groups supporting this hypothesis is as yet inconclusive. A specific antibody response might be masked in these patients by the wide antigenic homologies prevailing within the genus Mycobacterium. The present study was undertaken with the purpose of exploring the humoral response to M. paratuberculosis in patients with Crohn's disease, by means of a cross-absorption procedure recently proposed for unveiling the presence of specific antibodies in bovine paratuberculosis. Antibodies IgG to M. paratuberculosis were investigated by enzyme-linked immunosorbent assay in 90 serum samples from 17 patients with Crohn's disease, 23 patients with ulcerative colitis an 14 with other bowel diseases. Samples from 86 subjects without bowel disease (healthy individuals and patients with tuberculosis, mycobacterioses and fungal diseases) were also included as controls. The specificity of these antibodies was explored by the absorption of sera with an ubiquitous Mycobacterium (M. phlei). The results were compared to those obtained by similar ELISA tests employing M. avium or M. tuberculosis as antigens. A faint humoral response to M. paratuberculosis and M. tuberculosis was detected in patients with Crohn's disease. Cross-absorption with M. phlei did not disclose a specific response nor was an increase in antibody levels detected in patients studied periodically. Sera from patients with ulcerative colitis and other bowel diseases also showed a slight reaction to mycobacteria.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

A behavioral treatment program as a therapy in the control of primary hypertension.

In order to assess the effects of a Behavioral Treatment Program in the control of primary hypertension, twenty one unmedicated hypertensives were randomly allocated to three groups: first, a treatment group (BHG) receiving a Behavioral Treatment which included: deep muscle relaxation, peripheral temperature Biofeedback and anxiety management training; second, the placebo attention control group (PHG) and third, a control group of hypertensives too (CHG). Additionally, were compared with seven normotensives subjects (CNG). The post-treatment measures showed a significant reduction (p < 0.001) in systolic and diastolic values only in the (BHG). In a six months follow-up the (BHG) group still showed a significant reduction in the systolic and diastolic BP (p < 0.02; p < 0.01). Moreover individual variations in response to treatment were observed in this group, (BHG).

Adult↗
PubMed1993

Muir-Torre syndrome associated with a family history of hyperlipidemia.

The Muir-Torre syndrome is a rare disorder characterized by sebaceous neoplasms of the skin and multiple visceral malignancies. The syndrome appears to be a familial, autosomal dominant condition. We diagnosed this syndrome in a previously unreported patient and found a personal and family history of malignancies and hyperlipidemia. The association of Muir-Torre syndrome with a family history of hyperlipidemia, another autosomal dominant condition, has not been previously reported. The possible genetic relationship between the two disorders is discussed.

Aged↗
PubMed1993

Plants used in Guatemala for the treatment of dermatophytic infections. 2. Evaluation of antifungal activity of seven American plants.

From 52 plants screened for antifungal activity, 26 (50%) were active against dermatophytes. This paper reports further evaluation of seven American plants against four pathogenic fungi (Aspergillus flavus, Epidermophyton floccosum, Microsporum gypseum and Trichophyton rubrum), the part showing most activity, the best solvent and, in three cases, the minimal inhibitory concentration (MIC) against the fungus in pure culture. Antifungal activity was confirmed in all of the plants, but not all parts; the most active parts were the bark and leaves. The most active species were Byrsonima crassifolia, Cassia grandis, Gliricidia sepium and Malpighia glabra. Diphysa robinioides, Rhizophora mangle and Cassia occidentalis were less active. The most susceptible fungi were E. floccosum and T. rubrum; A. flavus was not susceptible. Ethanol was usually the best solvent and the MIC of C. grandis, C. occidentalis and D. robinioides was 50 micrograms/ml.

Antifungal Agents↗
PubMed1992

Humoral response to Mycobacterium tuberculosis in patients with human immunodeficiency virus infection.

The effect of the human immunodeficiency virus (HIV) on mycobacterial antibody production was investigated. Using an enzyme-linked immunosorbent assay (ELISA) for detecting IgG against Mycobacterium tuberculosis PPD, it was observed that individuals at risk of HIV infection show a pattern of humoral response to the tubercle bacillus similar to that previously found in the immunocompetent population not exposed to risk factors: 6 of 12 (50.0%) tuberculosis cases had elevated levels of antibodies to PPD and 27 of 30 (90.0%) asymptomatic individuals had antibody levels within the normal range. In an HIV-seropositive group without AIDS indicator diseases, 8 of 22 (36.4%) tuberculous patients had detectable mycobacterial antibodies whereas 156 of 164 (95.1%) non-tuberculous subjects did not. Among AIDS cases, only 1 of 20 (5.0%) patients with tuberculosis and none of 53 non-tuberculous subjects showed a positive result. The study evidenced an increasing humoral unresponsiveness to PPD in the progression of HIV infection to AIDS. Thus, a serodiagnostic method for detecting tuberculosis such as the ELISA here employed noticeably decreases its utility in the latency stage of the HIV infection, and it is practically useless in clinical AIDS.

AIDS-Related Opportunistic Infections↗