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Biomedical subjects

R Lopez

Publications and source records attributed to R Lopez.

At least 91 records · Page 5Linked to original sources
PubMed1994

Are the associations between Alzheimer's disease and polymorphisms in the apolipoprotein E and the apolipoprotein CII genes due to linkage disequilibrium?

Allele frequencies for polymorphisms in the apolipoprotein E and the apolipoprotein CII genes were determined in subjects of Ashkenazi Jewish origin with late-onset Alzheimer's disease and in unaffected control subjects from the same ethnic group. A significant association was observed between late-onset Alzheimer's disease and the epsilon 4 (112Cys-->Arg) allele of apolipoprotein E; however, no association was detected with apolipoprotein CII. These results suggest that the association with epsilon 4 is probably not due to linkage disequilibrium.

Aged↗
PubMed1994

In vitro sequence-dependent synergistic effect of suramin and camptothecin.

Suramin, a hexasulphonated naphthylurea with activity in prostatic cancer, possesses a wide variety of antitumour mechanisms of action, one of which is the inhibition of topoisomerase II. In this in vitro study, suramin was combined with the topoisomerase I inhibitor, camptothecin. Several suramin concentrations (0.2-3000 microM) were combined with camptothecin (0.4 pM-20 microM) in MCF-7 and PC3 human cancer cell line cultures. In addition, we studied the topoisomerase II and I gene expression by northern blot analysis, and the cell cycle distribution by flow cytometry, after exposure to suramin. While there was only an additive effect when suramin and camptothecin were added simultaneously, a remarkable synergism was obtained when camptothecin was added after a 3-day exposure to suramin. Topoisomerase II and I gene expression and the number of cells in S phase were significantly reduced after exposure to suramin. In conclusion, interaction of suramin with camptothecin is schedule-dependent and can be synergistic. These findings might help in identifying optimal combinations of suramin or other topoisomerase II inhibitors, with topoisomerase I inhibitors.

Camptothecin↗
PubMed1994

A predictive model for fetal lung maturity employing gestational age and test results.

Most laboratory tests for fetal lung maturity (FLM) are optimized to exclude false-negative predictions of absence of respiratory distress syndrome (RDS), with a reciprocal low predictive value for maturity. The authors employed FLM Surfactant/Albumin Ratio (FLM S/A) test results to construct a predictive model for FLM that included the obstetric estimates of gestational age. The charts of 388 newborns were abstracted and reviewed. The clinical outcome was the gold standard of the multivariate logistic analysis. Both the obstetric estimates of gestational age and the test result were significant predictors of the clinical outcome (P values of < .0002 and .001, respectively). The prediction rule for RDS as a function of both of these variables allows for adjustment of the test cutoffs, so that there is a consistent probability of RDS at the cutoff FLM S/A result for different gestational ages. Fetal lung maturity probability reporting may facilitate clinical decision-making.

Albumins↗
PubMed1994

Intraocular blastomycosis: case report and review.

Intraocular infection due to Blastomyces dermatitidis is rare, and only 10 cases have previously been reported. Manifestations of ocular blastomycosis can range from keratitis to panophthalmitis, and it is often difficult to diagnose ocular blastomycosis early. We report the case of a 45-year-old man who had disseminated blastomycosis that involved the lungs, skin, and ocular uvea and who was successfully treated with systemic and local antifungal therapy. We also review the literature describing the spectrum of clinical findings due to intraocular blastomycosis.

Amphotericin B↗
PubMed1994

Comparison of Irlen scotopic sensitivity syndrome test results to academic and visual performance data.

UNLABELLED: Irlen has defined a condition called Scotopic Sensitivity Syndrome (SSS) that is associated with reading problems. According to Irlen, SSS can be treated by the use of colored filters, but there is disagreement about the existence of SSS and the efficacy of colored filter therapy. METHODS: Thirty-nine children participated in the study: 24 were academically normal, nine had specific reading problems, and six had problems in multiple academic areas. SSS levels and preferred overlay colors were determined. Optometric test data were also available for each subject. RESULTS: No significant relationships were found between academic classification and degree of SSS. There were also no significant relationships between preferred overlay color and any other variables. There was, however, a significant tendency for subjects with higher SSS levels to be candidates for vision therapy and to derive greater benefit from the colored overlays. CONCLUSIONS: Many questions about the use of colored filters for the treatment of reading problems remain unanswered. Among these are questions dealing with whether the M-pathway anomalies found in some dyslexics are also present to a lesser degree in other cases of reading disabilities, and how colored filters could re-balance the M- and P-pathways. Is it the color of the filter itself that is critical, or is it the change in luminance or contrast produced by the filter that seems to make it easier for some subjects to read? More research will be needed to answer these questions.

Child↗
PubMed1994

Taxonomical, clinical and pathological findings in moradilla (Lobelia-like) poisoning in sheep.

Each year during late winter and spring, grazing sheep and cattle in the State of Tamaulipas in northeastern Mexico develop toxicoses which have been empirically associated to consumption of a toxic plant locally known as moradilla. This investigation was undertaken to determine whether moradilla was a toxic plant not yet reported in Tamaulipas or was an unrecognized species of the Lobelaceae or Campanulaceae family. Taxonomic determination of moradilla plants collected from February to April showed that it was a species of Lobelia. Five alkaloids were identified by thin-layer chromatography in the mature stages of moradilla, while only 1 and 3 alkaloids were found in the growing and flowering stages of this plant, respectively. The alkaloids were not affected by making silage, drying in hay or freezing. Experimental intoxication of sheep with moradilla caused clinical signs and pathologic changes identical to those previously described for lobelia toxicosis. It was concluded that Lobelia berlandieri was the cause of moradilla toxicosis in grazing cattle and sheep of northeastern Mexico.

Animals↗
PubMed1993

Neoadjuvant chemotherapy and radiotherapy in locally advanced esophagus carcinoma: long-term results.

PURPOSE: A prospective study with neoadjuvant chemotherapy and radiotherapy in patients with locally advanced esophagus carcinoma for evaluating: toxicity, response rate, pattern of recurrence, and survival after a long follow-up. METHODS AND MATERIALS: Between 1983-1988, 40 patients with locally advanced squamous cell carcinoma of the thoracic esophagus were entered into a prospective trial of neoadjuvant chemotherapy and radiotherapy. Eight patients (20%) were Stage II and 32 patients (80%) were Stage III, according to American Joint Committee staging criteria. Neoadjuvant chemotherapy consisted of two cycles with cisplatin (120 mg/m2 day 1), vindesine (3 mg/m2 days 1, 8, 15, and 22) and bleomycin (10 mg/m2 days 3 to 6). Second cycle was initiated on day 29. Radiation therapy was administered 2-4 weeks after completion of chemotherapy, with a total dose on tumor of 60 Gy. RESULTS: Two patients died from treatment-related toxicity. Complete response was observed in 20 patients (53%) and symptomatic improvement in 31 patients (82%). The median survival was 11 months, with an actuarial survival at 1 year of 45%, 3 year 20%, and 5 years 15%. Significantly (p < 0.05) longer survival was observed in patients with Stage II (median survival 18 months) vs. Stage III (median survival 10 months). The pattern of failure was predominantly local/regional (62%). CONCLUSION: This treatment scheme is an effective and tolerable regimen but long-term survival was poor.

Adult↗
PubMed1993

Local secretory IgA in dogs with low systemic IgA levels.

Low plasma IgA concentrations are commonly found in clinically normal dogs. In order to ascertain the relative importance of local and systemic IgA concentrations as factors determining the absence of clinical signs, IgA concentrations in plasma and tears were assayed in clinically normal dogs with a deficiency of IgA (10.33 +/- 0.63 mg/dl). The IgA levels in tears (25.28 +/- 1.91 mg/dl) did not differ significantly from those of control dogs or from previously published data for dogs. Thus, low systemic levels did not imply a significant reduction in local IgA levels. The absence of clinical signs in dogs with low plasma IgA concentrations may therefore be explained by the presence of normal secretory levels and an effective immune response against local pathogens.

Age Factors↗
PubMed1993

Parental smoking and risk of childhood brain tumors.

Data from a large, population-based, case-control study were analyzed to assess the role of parental smoking in childhood brain tumors. Parents of 361 cases, newly diagnosed between January 1, 1977 and December 31, 1981 and ascertained from eight Surveillance, Epidemiology, and End Results (SEER) program registries, and 1,083 controls had been interviewed. No significant differences in risks were found to be associated with maternal or paternal smoking at any time (odds ratio (OR) = 0.92 for mothers and 1.06 for fathers), during the year of birth of the child (which included both the prenatal and postnatal periods) (ORs = 0.84 for < 1 pack/day and 1.0 for > or = 1 pack/day for mothers, and 0.68 for < 1 pack/day and 1.07 for > or = 1 pack/day for fathers), or 2 years before the child was born, i.e., the pre-conception period (ORs = 0.75 for < 1 pack/day and 1.01 for > or = 1 pack/day for mothers, and 0.90 for < 1 pack/day and 1.15 for > or = 1 pack/day for fathers). Mothers were also specifically asked if they smoked during the pregnancy, and no association was found compared with never smokers (OR = 1.08, 95% confidence interval (CI) 0.80-1.45) or for ever-smokers who continued to smoke during pregnancy compared with those who stopped smoking during pregnancy (OR = 1.15, 95% CI 0.75-1.78). Finally, no significant increase in risk of brain tumors was found for the child's passive exposure to parental smoking during the period from birth to diagnosis of the brain tumor in the case. The lack of an effect of parental smoking was observed for both the major histologic types and locations of brain tumors. These findings and those from earlier studies provide no support for the hypothesis that parental cigarette smoking influences the risk of brain tumors in children.

Adult↗
PubMed1993

Effect of anthelmintic treatment on the allergic reactivity of children in a tropical slum.

It is well known that helminthic infection can cause a polyclonal stimulation of the synthesis of IgE, which is dependent on interleukin-4 (IL-4) production, and it has been suggested that this can modulate the expression of allergic reactivity in tropical populations. We evaluated the effect of regular anthelmintic treatment, for a period of 22 months, on certain aspects of the allergic reactivity of children in a slum area of Caracas, Venezuela, where helminths are endemic. The treatment (Oxantel-Pyrantel; Quantrel) effectively eliminated intestinal helminthic infection and resulted in a significant decrease in the initially elevated total serum IgE levels. IL-4 was detectable in the serum, and a significant reduction in IL-4 was also observed after treatment. In contrast, both the immediate-hypersensitivity skin-test reactivity and serum levels of specific IgE antibody against environmental allergens were markedly increased in the treated children. In a group of children who were also evaluated in the same slum, but who declined treatment, a substantial increase in helminthic infection occurred, which was related to an acute deterioration of the socioeconomic conditions of Venezuela over the course of our study period. This was paralleled by a considerable increase in total IgE levels in these children and a decrease in the skin-test reactivities and specific IgE levels. The application of Prausnitz-Küstner passive transfer tests and analysis of specific IgE antibody levels indicated that the polyclonal stimulation of IgE synthesis by helminthic parasites results in mast cell Fc epsilon receptor saturation and suppression of specific IgE antibody synthesis. This inhibition of allergic reactivity is reversible by anthelmintic treatment.

Adolescent↗
PubMed1993

Analysis of the c-FOS gene on chromosome 14 and the promoter of the amyloid precursor protein gene in familial Alzheimer's disease.

The c-FOS gene product, a putative transacting transcriptional regulator of the amyloid precursor protein (APP) gene, is a candidate locus for the familial Alzheimer's disease (FAD) mutation on chromosome 14 (FAD14). In light of this functional relationship, we investigated the nucleotide sequence and segregation of c-FOS and the nucleotide sequence of the 5' APP promoter. Single-stranded conformational polymorphisms (SSCPs) in the c-FOS gene revealed that c-FOS closely cosegregates with the FAD14 gene but does not show allelic association with FAD. A conservative third-position T-->C mutation was demonstrated in exon 2 (codon 84) of c-FOS, and a C-->G substitution was detected at -209 bp in the 5' promoter of APP. Neither were unique to FAD and are unlikely to be pathogenic or secondary modifiers of the FAD phenotype. We conclude that the c-FOS open reading frame is probably not the site of the FAD14 locus, but we cannot exclude the existence of modifier loci on chromosome 21.

Adult↗
PubMed1992

Cloning of a gene from Bacillus cereus with homology to the mreB gene from Escherichia coli.

We have cloned and sequenced a gene coding for a putative shape-determining protein (MreB) highly homologous to the mreB gene product of Escherichia coli. The amino acid (aa) identity was 53% and the similarity 72%. The gene is expressed early in the logarithmic phase. The aa sequence comparison showed that the protein, like the E. coli MreB, has structural similarity to actin and heat-shock protein Hsc70 encoded by a new super-gene family.

Amino Acid Sequence↗
PubMed1992

Long-term results of vitrectomy and perfluorocarbon gas for the treatment of severe proliferative vitreoretinopathy.

The results of 87 patients who underwent vitrectomy, scleral buckling, and injection of perfluorocarbon gas in one eye each for proliferative vitreoretinopathy of grade C3 (marked, involving three quadrants) or worse were studied. The retinas of 60 of the 87 patients (69%) were attached posterior to the scleral buckle one month after disappearance of the gas, with the initial reattachment rate being inversely proportional to the severity of proliferative vitreoretinopathy. Follow-up data ranging from six to 106 months were available on 54 eyes with attached retinas. Final visual acuity in those patients ranged from light perception to 20/40 and was not related to severity of proliferative vitreoretinopathy or duration of reattachment. Thirty-eight of the 54 patients (70%) had a visual acuity of 20/400 or better. Twenty-nine of the 37 patients (78%) with retinas attached 24 months or longer had the same or better visual acuity than at six months postoperatively. Macular pucker was observed in 16 of the 54 eyes (30%) and was the most frequently seen long-term retinal complication affecting visual acuity.

Adolescent↗