PubMed Health⌕ Search

Biomedical subjects

R Lopez

Publications and source records attributed to R Lopez.

At least 91 records · Page 5Linked to original sources
PubMed1995

Durability of the Carpentier-Edwards porcine bioprosthesis: role of age and valve position.

The durability (structural deterioration-free interval) after valve implantation with the first-generation Carpentier-Edwards porcine bioprosthesis has been investigated. From 1978 through 1984, 420 patients (175 male, 245 female) underwent valve replacement with the Carpentier-Edwards standard bioprosthesis. Mean age was 50.6 years (range, 13 to 77 years). Isolated mitral valve replacement (MVR) was performed in 198 patients (47.1%), aortic valve replacement (AVR) in 136 (32.4%), and double valve replacement (DVR) in 86 (20.5%). Hospital mortality was 32 patients (7.6%), 7.5% for MVR, 5.1% for AVR, and 11.6% for DVR. Mean follow-up was 10.8 years (range, 9 to 15 years) and is 96.2% completed. Reoperation for structural deterioration was required in 143 patients. Actuarial curve free from structural deterioration at 15 years is 33.0% +/- 6.5% for MVR, 62.0% +/- 5.1% for AVR, and 44.2% +/- 8.2% for DVR (p < 0.03). Durability of the CE bioprosthesis for MVR was 101.6 +/- 34.5 months, 92.9 +/- 26.4 for AVR, and 84.3 +/- 25.3 for DVR (p = not significant). The regression logistic analysis between age at the time of surgery and durability of the bioprosthesis showed no correlation for the MVR group, but with the following predictive formula for AVR and DVR groups of patients older than 30 years" durability = 46.05 + 0.818 x age, for AVR (r2 = 0.43); durability = 15.81 + 1.122 x age, for DVR (r2 = 0.52). In conclusion, we have found a significant difference in the behavior of the CE porcine bioprosthesis between the mitral and aortic position.(ABSTRACT TRUNCATED AT 250 WORDS)

Actuarial Analysis↗
PubMed1995

The focal cone electroretinogram.

The focal cone electroretinogram (ERG) in monkey retina has been examined with a 3 deg pulse of laser light (544 and 633 nm) centered on a 25 deg steady white rod saturating field. The stimuli were viewed simultaneously through a slit lamp and corneal contact lens. Cone ERGs were studied at different eccentricities from the fovea and compared with full-field corneal and intraretinal ERGs. The cone ERG is maximum at the fovea. There are two components to the on- (b-wave) and off- (d-wave) response, one slower, more long wavelength sensitive and more foveally oriented than the faster response. This makes the foveal cone ERG slower and more longer wavelength sensitive than the perifoveal ERG. This difference disappears at high rates (> 20 Hz) of stimulation. The foveal cone ERG is larger and slower than that of more peripheral retina. The slowness appears to be due to a subcomponent of the response which is especially prominent in the fovea and has a slightly greater long wavelength sensitivity than the more peripherally generated ERG. It may depend on a unique difference in L-M cone bipolar systems or in L-M cone interactions that are more prominent near the fovea.

Animals↗
PubMed1995

Retroviral gene transfer into retinal pigment epithelial cells followed by transplantation into rat retina.

In this preliminary report, we describe a technique for gene transfer into the retina using a retrovirus vector. We transferred the bacterial LacZ gene and the neomycin-resistance gene into pigmented wild-type rat retinal pigment epithelial (RPE) cells in culture. The RPE culture was exposed to retrovirus, and infected cells were selected with a neomycin analog (G418). The LacZ gene product was detected by X-Gal histochemistry in 95-100% of drug-resistant cells. These genetically labeled cells were transplanted into the subretinal space of two 15- to 25-day-old albino RCS rats, which have an inherited retinal degeneration syndrome. The retinas were fixed and stained with X-Gal at 3 and 6 weeks after transplantation. At both time points, pigmented, LacZ-containing cells were seen in the subretinal space. Further, there were several rows of photoreceptor nuclei in the transplant area of the approximately 2-month-old rats, while in the control contralateral eye the photoreceptor nuclei were virtually absent, as for untreated animals, suggesting that the transplanted LacZ-marked, wild-type RPE cells may have helped preserve photoreceptors. The technique for gene transfer into RPEs followed by transplantation thus provides a means for gene therapy in organisms with a genetic defect in RPE cells.

Animals↗
PubMed1995

A standard water provocative test for dogs anaesthetized with acepromazine-ketamine.

Administration of 60 ml/kg of water to anaesthetized dogs increased intraocular pressure; this reached its maximum at 15 min after ingestion, except in young dogs, whose maximum was attained at 10 min. Pressure fell back close to original levels by 60 min. Pressure increases in females and young dogs were greater than those of males and adults, respectively.

Acepromazine↗
PubMed1995

Portal vein patency in candidates for liver transplantation: MR angiographic analysis.

PURPOSE: To assess the accuracy of magnetic resonance (MR) angiography for evaluating portal vein patency in candidates for liver transplantation. MATERIALS AND METHODS: MR angiography was performed in the main portal vein and proximal confluence of the portal vein in 102 candidates for liver transplantation (64 male patients and 38 female patients aged 8 months to 74 years; mean age, 47 years). The MR angiographic results were compared with the surgical and histologic findings in the explanted liver and excised main portal vein. RESULTS: MR angiography depicted 10 portal vein clots, all of which were confirmed at transplantation. Ninety-two portal veins were patent at MR angiography, a finding that was confirmed at transplantation. One tiny chronic clot in a small, intrahepatic branch of the portal vein was not seen at MR angiography or transplantation. It was identified at histologic analysis of the explanted liver. CONCLUSION: MR angiography is accurate in the evaluation of portal vein patency.

Adolescent↗
PubMed1995

Farm-related fatalities among children in California, 1980 to 1989.

To evaluate farm-related deaths among children in California and to identify specific risk factors, this study used death certificate tapes to identify 40 farm-related deaths among children under age 15 in California for 1980 to 1989. Mortality rates and odds ratios for cause-specific unintentional farm deaths were calculated. While California's farm-related mortality rate was lower than those in the midwestern states studied, the rate for Hispanic boys was 70% higher than that for non-Hispanics. The odds of death from machinery (81.3), animals (10.1), electricity (5.2), and nontraffic motor vehicles (3.4) were significantly greater than those in nonfarm locations; those from drowning were significantly lower (0.2). Specific factors associated with the lower California mortality rate need to be identified.

Accidents↗
PubMed1995

Patch transplants of human fetal retinal pigment epithelium in rabbit and monkey retina.

PURPOSE: To transplant human fetal retinal pigment epithelium (RPE) into the subretinal space of rabbits and monkeys as an organized monolayer without artificial support. METHODS: The method involves dissecting small patches of cultured RPE monolayers in sheets (1 to 5 mm2), sucking them into a glass pipette and injecting them into the subretinal space after producing a bleb detachment of the neural retina. RESULTS: These patches unfold and survive as a quasi-monolayer under the reattached neural retina intimately associated with the host photoreceptors and phagocytizing host outer segment material. Graft rejection is observed in most rabbits at 1 month but not in monkeys at 3 months after transplantation. CONCLUSIONS: Monolayer patches of cultured human fetal RPE can be transplanted to the subretinal space, where they survive in contiguity with healthy host outer segments. In primates, but not in rabbits, host-graft rejection does not occur for at least 2 to 3 months.

Animals↗
PubMed1994

Evaluation of the exon predictions of the GRAIL software.

Identification of transcribed sequences within genomic regions has been a major rate-limiting step in the pursuit of genes. We have tested the ability of GRAIL 1 and GRAIL 2 to locate coding exons in the 41 longest human genomic sequences available in release 38 of the EMBL database. Of the total annotated exons GRAIL 1 correctly identified 68% of coding exons. GRAIL 2 correctly identified 71%. Of the 686 predictions made by GRAIL 1, 46.4% did not correspond to an annotated exon. The corresponding figures for GRAIL 2 were 556 and 30.5%. The GRAIL 2 software predicted as excellent a significantly higher proportion of the coding exons than did GRAIL 1, and also gave a significantly lower figure for false predictions. GRAIL 2 thus represents a significant improvement over GRAIL 1.

Exons↗
PubMed1994

The role of family history in risk of childhood brain tumors.

BACKGROUND: Although brain tumors are the second most frequent malignancy in children, relatively little is known about the role of family history in risk of these tumors. METHODS: Children under the age of 18 years (n = 361) in whom primary brain tumors were diagnosed were identified from eight United States population-based Surveillance, Epidemiology, and End Results registries and compared to matched controls (n = 1083) identified by random-digit dialing. Information regarding family history of birth defects or tumors was obtained, along with data on other potential risk factors, from interviews with the mothers and fathers of the index children. RESULTS: No significant differences were found in family history of epilepsy. However, moderate elevations in risk were observed for a history of birth defects in maternal relatives, particularly for female propositi. Significantly more mothers (odds ratio [OR] = 1.63, 95% confidence limits [CL] = 1.03, 2.57) and maternal female relatives (OR = 2.15, 95% CL = 1.14, 4.06) of cases than of controls were reported to have had birth defects. History of birth defects in maternal relatives was particularly associated with childhood brain tumors of "other" (not astrocytoma or medulloblastoma) histologic type (OR = 2.37, 95% CL = 1.25, 4.53) and infratentorial tumors (OR = 1.76, 95% CL = 1.06, 2.93). Slight excesses of tumors were observed in paternal relatives of children with astrocytomas (OR = 1.43, 95% CL 0.93, 2.20) or with infratentorial tumors (OR = 1.46, 95% CL 0.97, 2.20). Risk of childhood brain tumors did not increase with the number of relatives affected with brain tumors, breast cancer, leukemia or lymphoma, soft tissue sarcomas, or all of these tumor types combined (the Li-Fraumeni syndrome). CONCLUSIONS: These findings suggest a modest increase in risk of childhood brain tumors associated with maternal family history of birth defects. Family history of tumors does not appear to contribute appreciably to an increased risk of brain tumors in children.

Adolescent↗
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↗