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Biomedical subjects

L Peña

Publications and source records attributed to L Peña.

47 records · Page 3Linked to original sources
PubMed1992

The ergonomic challenge of repetitive motion with varying ergonomic stresses. Characterizing supermarket checking work.

Many jobs leading to a risk of cumulative trauma do not have highly stereotyped motions. This study developed and employed a novel method of ergonomic characterization to describe quantitatively the actions associated with grocery checking. Fifty workers were videotaped for three 15-minute segments each. Eight object types were selected to represent the variety of items in a supermarket. Nine types of motion were coded for each of the eight objects for 10 replications for each subject. The motions coded were: grip type (power versus pinch), wrist flexion, wrist extension, radial deviation, ulnar deviation, supination, pronation, body (lumbar) flexion, and drag versus lift. The results were then weighted according to relative frequency of the object type. In this manner, an ergonomic risk index can be assigned to each specific object type. This method permits identification of objects presenting the greatest risk. It also allows specificity of preventive interventions (object redesign, work practice change) as well as providing a quantitative measure to evaluate work station redesign. Furthermore, it has the potential of quantitatively describing the risk of each individual worker.

Cumulative Trauma Disorders↗
PubMed1991

Flow cytometric analysis of oestrogen receptors in relation to histopathologic characteristics of DMBA-induced mammary tumours in rats.

Experimental DMBA (7,12-dimethylbenzanthracene)-induced mammary tumours in Sprague-Dawley rats are studied. Percentages of the distinct types of adenocarcinomas (Stevens et al. 1965) were as follows: type A (poorly-differentiated), 8.8%; type B (well-differentiated), 65.5%; type C (atrophic), 15.5% and type D (secretory), 5.4%. 51% of the mammary adenocarcinomas were seen to be positive to oestradiol receptors by means of flow cytometry; type A adenocarcinomas were found to be the most frequent positive tumours (88.9% positive cases) whereas the last adenocarcinomas to appear (type D) were negative. These results suggest that the oestradiol-sensitivity of DMBA-induced mammary adenocarcinomas decreases as the post tumour-induction period lengthens.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1990

Transformed tomato plants express a satellite RNA of cucumber mosaic virus and produce lethal necrosis upon infection with viral RNA.

Tomato plants transformed with a single copy of a tomato necrosis causing satellite RNA of cucumber mosaic virus (CMV) express the satellite sequence, but the plants show no disease symptoms and have a normal appearance. Upon challenge infection of the F1 progeny with a CMV strain free of any detectable encapsidated satellite the plants accumulated single and double-stranded forms of satellite RNA and developed lethal necrosis.

Blotting, Northern↗
PubMed1990

Intermediate filaments in DMBA-induced mammary adenocarcinomas in rats.

Experimental DMBA (7,12-dimethylbenzanthracene)-induced mammary tumours in rats were studied. Microscopic examination revealed a high rate of adenocarcinomas (95.3% in 148 mammary tumours studied). An immunohistochemical study of cytoskeleton intermediate filaments (I.F.) showed cytokeratins in neoplastic epithelial cells; myoepithelial cells expressed cytokeratins, vimentin and desmin. Finally we propose the immunocytochemical localization of desmin as a useful method to recognize myoepithelial proliferation areas in mammary tumours.

Adenocarcinoma↗
PubMed1979

A comparative study of two diets in the treatment of primary exogenous obesity in children.

One hundred four children, six to fourteen years of age, with primary exogenous obesity were randomly distributed in order to be subjected to two different diets, ketogenic (low carbohydrate) and hypocaloric, for eight weeks. Body weight, serum triglycerides, cholesterol, a glucose tolerance test, blood glucose and plasma insulin determination were performed before and after both diets. The results revealed significant differences in body weight and triglyceride concentrations with the two diets although they were more remarkable with the ketogenic diet. There were significant differences in the fasting insulin levels, insulinogenic index, and insulin concentration after a glucose tolerance test in the patients subjected to a ketogenic diet.

Adolescent↗
PubMed1977

Incontinentia pigmenti achromians (Ito's hypomelanosis).

A 2-year-old Mexican girl had hypochromic lesions characteristic of incontinentia pigmenti achromians on the right half of the body. Extra cutaneous alterations were: dacryostenosis, bilateral genu valgus,ataxic gait, language retardation, hydrocephaly and abnormal electroencephalogram. Electron microscopy showed numerous Langerhans cells in the epidermis.

Adult↗
PubMedDate not supplied

H-ras immunohistochemical expression and molecular analysis of urinary bladder lesions in grazing adult cattle exposed to bracken fern.

Chronic ingestion of bracken fern (Pteridium spp.) by cattle produces upper alimentary tract and urinary bladder tumours causing a syndrome called bovine enzootic haematuria (BEH). Previous studies demonstrated ptaquiloside-DNA adducts and mutations in the h-ras gene in ileal epithelial cells of bracken fern-fed calves. Systematic inspection of the bladder mucosa of grazing cattle (n=126) from bracken-fern areas was carried out in a slaughterhouse. Of the 126 slaughterhouse cattle, 46 showed macroscopical lesions of the bladder. These bladders, together with six others known to have BEH, were examined histopathologically and by H-ras immunohistochemistry. Thirteen affected bladders were also examined by H-ras molecular analysis to detect mutations. Macroscopical and histological study of urinary bladder lesions found at the slaughterhouse revealed chronic cystitis (34.1%) and tumours (2.4%). There was significantly increased immunohistochemical expression of H-ras (P<0.05) in chronic cystitis (H-ras=53.24%) and bladder tumours (H-ras=63.60%) as compared with normal urinary bladders (H-ras=4.32%). A silent mutation (D38D) was detected in one animal with a mixed bladder tumour. The prevalence of urinary bladder lesions (chronic cystitis and tumours) obtained at the slaughterhouse was higher than expected. This study demonstrates that close inspection of urinary bladders of adult grazing cows is necessary to prevent possible human exposure to bracken-fern carcinogens. The absence of mutations in the codons of h-ras studied did not exclude the presence of polymorphisms in other regions of the gene (promoter or regulation sequences) or in other genes (belonging or not to the ras family) that significantly affect the H-ras protein.

Animals↗
PubMedDate not supplied

Relation between habitual diet and canine mammary tumors in a case-control study.

In the present case-control study several dietary and nutritional factors were investigated to determine if a relationship exists between diet and development of mammary tumors in female dogs. Control female dogs (n = 86) were compared with a case group of dogs (n = 102) with dysplasias or tumors of the mammary gland. A questionnaire providing information on the dog's body conformation and dietary and reproductive histories was answered by the owners. Serum selenium and retinol concentrations and the fatty acid profile in subcutaneous adipose tissue were analyzed as indicators of nutritional status. Obesity at 1 year of age and 1 year before the diagnosis of mammary nodules was found to be significantly related to a higher prevalence of mammary tumors and dysplasias. The intake of homemade meals (compared to that of commercial foods) was also significantly related to a higher incidence of tumors and dysplasias. Other significant risk factors were a high intake of red meat, especially beef and pork, and a low intake of chicken. The subcutaneous fatty acid profile and the serum selenium concentration were not significantly different in the cases and the controls, with the exception of C18:1 fatty acid (oleic acid) content, which was significantly higher in the cases than in healthy controls. Serum retinol concentration was significantly lower in the cases than in the controls. In the multivariate analysis, older age, obesity at 1 year of age, and a high red meat intake were independently and significantly associated with the risk of developing mammary tumor and dysplasias.

Animals↗