Biomedical subjects

L Peña

Publications and source records attributed to L Peña.

At least 37 records · Page 2Linked to original sources

PubMed1998

Binding of sodium salicylate by beta-cyclodextrin or 2,6-di-O-methyl-beta-cyclodextrin in aqueous solution.

Speed of sound and conductivity experiments have been done at 298.15 K to study the encapsulation process of sodium salicylate (NaSA) by beta-cyclodextrin (beta-CD) and 2,6-di-O-methyl-beta-cyclodextrin (DIMEB) in aqueous solutions. Since the concentration of the salicyclic form (HSA), coming from the hydrolysis of SA-, is negligible at biological pH, the binding process studied in this work is that of the SA- species. The stoichiometries of the complexes DIMEB: SA- and beta-CD:SA- have been found to be 1:1, as usually determined for most CD:drug complexes. Their association constants and their ionic molar conductivities at infinite dilution have been obtained by fitting the experimental conductivity data with a nonlinear regression method (NLR). For that purpose, a model based on that of Gelb and co-workers has been used. From the values of K beta-CD:SA- = (105 +/- 15)M-1 and KDIMEB:SA- = (140 +/- 20)M-1 obtained, the bioavailability of the salicylate drug in the complexed form has been discussed.

Anti-Inflammatory Agents, Non-Steroidal↗

PubMed1998

[The relation of Helicobacter pylori with dysplasia and stomach neoplasms in Costa Rica].

Occurrence of the bacterium Helicobacter pylori was compared for two Costa Rican sites with contrasting levels of gastric cancer incidence, Poás (incidence 15.13%) and Puriscal (83.53%). A sample of 185 adults of similar age and sex proportions was studied in each site, using both H. pylori antiserum tests and gastroscopy to collect two biopsies per case. No clear association between H. pylori and gastric cancer was found.

Adult↗

PubMed1997

Clinical and pathological prognostic factors in canine mammary tumors.

In the present study, clinical and reproductive variables and pathological features were evaluated as prognostic factors in canine mammary tumor disease. Seventy-four female dogs free of distant metastases at diagnosis were followed-up during a period of 18 months after the surgical excision of mammary nodules. Age at presentation, tumor size, lymph node involvement, histological malignant grade and nuclear grade were proven to act as variables able to predict the overall survival time in dogs with mammary neoplasms. Disease free survival time was associated to the age, the presence of multiple malignant tumors, tumor size and ulceration of the skin.

Age Factors↗

PubMed1996

Immunocytochemical detection of growth factors (PDGF and TGF beta) in equine chronic pneumonia.

The roles played by platelet-derived growth factor (PDGF) and transforming growth factor beta (TGF beta) in the development of pulmonary fibrosis in equine chronic pneumonia varied greatly. Macrophages, epithelial cells and fibroblasts were identified as a source of PDGF, the principal role of which was related to its mitotic effect on epithelial cells, and particularly on fibroblasts in the final phase of the disease. TGF beta was detected in epithelial cells in all three phases of the disease and in fibroblasts in the last phase. However, the role of TGF beta in this pulmonary disease is not clear because its expression in the cytoplasm of fibroblasts in areas of strong collagenation during the last phase was weak. Nonetheless, it was responsible for the production and release of collagen during the stage of total fibrosis.

Animals↗

PubMed1996

Immunohistological study of IgA, IgG and IgM in endoscopic biopsies of dogs with plasmacytic-lymphocytic colitis.

The results of a histological and immunohistochemical study of endoscopic colon biopsies of dogs with plasmacytic-lymphocytic colitis are reported. The histological study revealed that a characteristic infiltrate rich in lymphocytes and plasma cells was seen within the lamina propria in all the biopsies. The immunohistochemical investigation suggests that IgG is the major antibody in the immune response of dogs with plasmacytic-lymphocytic colitis.

Animals↗

PubMed1996

[Felodipine in the treatment of essential arterial hypertension in elderly patients].

BACKGROUND: Felodipine is a calcium channel inhibitor with high vascular selectivity. AIM: To study the effectiveness of felodipine in the treatment of essential hypertension in subjects older than 64 years old. PATIENTS AND OUTCOME: Fifty subjects were studied. After a washout period of four weeks, subjects received a placebo for two weeks followed by the active drug given in an initial dose of 5 mg/day, adjusted to 10 and 20 mg every 21 days if normal blood pressure levels were not attained. RESULTS: Compared to the placebo period, Felodipine treatment reduced blood pressure from 173 +/- 7.5/102 +/- 3.3 mm Hg to 158 +/- 6.3/91 +/- 4.2 mm Hg. There was no orthostatic reduction of blood pressure, and 87% of subjects attained systolic and diastolic pressure levels below 140 and 90 mm Hg respectively. Adverse reactions (edema, cephalea and flushing) were reported by 38% of subjects and in three, the drug was discontinued. There were no changes in laboratory parameters during the treatment period. Quality of life improved during treatment in the items of concentration, health status perception, mood, physical condition, depression, effects of hypertension on life events and initiative. CONCLUSIONS: Felodipine is effective in the treatment of elders with essential hypertension.

Aged↗

PubMed1995

Clinical characteristics of 16 cystic fibrosis patients with the missense mutation R334W, a pancreatic insufficiency mutation with variable age of onset and interfamilial clinical differences.

We present the genotype/phenotype correlation analysis for 16 cystic fibrosis (CF) patients who carry mutation R334W. Current age and age of diagnosis was significantly higher in the R334W/any-mutation group (P < 0.05 and P < 0.01), compared with the delta F508/delta F508 group. A slightly, but not significantly, worse lung function was found in the R334W/any-mutation group, when compared with the delta F508/delta F508 patients. The proportion of patients with lung colonization with bacterial pathogens was slightly, but not significantly, higher in the R334W/any-mutation group (71.4%), compared with the delta F508/delta F508 or R334W/delta F508 groups (55.5%). None of the R334W patients had meconium ileus but 60% were pancreatic insufficient (PI), a significantly lower proportion (P << 0.001) than delta F508/delta F508 patients. Two R334W/N1303K compound heterozygous sisters of three sibs with genotype R334W/delta F508 showed interfamilial discordant clinical data for lung and pancreatic function. The data provided here for mutation R334W demonstrate that this mutation is responsible for a less severe form of CF than delta F508. Interfamilial differences for PI and lung function suggest that other factors, viz. genetic, environmental and medical, contribute to the wide spectrum of clinical differences observed in CF patients with the same CF transmembrane conductance regulator genotypes.

Age of Onset↗

PubMed1995

DNA flow cytometry of canine mammary tumours: the relationship of DNA ploidy and S-phase fraction to clinical and histological features.

The DNA ploidy status and S-phase fraction (SPF) of benign proliferative lesions (BPL) and malignant tumours (MT) in the mammary glands of dogs were determined by flow cytometric analysis and the results were related to their clinical and histological features. Seven (14.3 per cent) of 49 BPL and 16 (48.5 per cent) of 33 primary MT had aneuploid G0,1 peaks (P < 0.001). Hypodiploid G0,1 peaks were found in one BPL and in five primary MT. The DNA ploidy status of primary MT was not found to be associated with their size, nodal status, grade of histological malignancy or nuclear grade. In several cases there was intra-tumour heterogeneity in ploidy status independent of histological heterogeneity. The SPF was significantly higher in 27 primary MT than in 45 BPL when diploid and aneploid cases were combined for comparison (P < 0.05), but not when only diploid cases were compared. Among the primary MT the SPF was higher in aneuploid than in diploid tumours (P < 0.05) and it was higher in five MT from five dogs with regional disease than in 22 MT from 19 dogs with local disease (P < 0.05). The SPF was positively correlated with the grade of histological malignancy (P < 0.05) but not with nuclear grade.

Animals↗

PubMed1995

Eosinophilic gastroenteritis syndrome in a dog.

We performed a clinical and pathological study of a 5 year old female mongrel dog (Drahthaar) with eosinophilic gastroenteritis. The animal was presented with vomiting and was reported to have had bloody diarrhoea for 4 months. The lesions were in atypical locations: in the fundus of the stomach, the ileocaecal valve and the rectum, near the anal sphincter. The lesions in the stomach wall were particularly severe and included severe fibroplasia, especially in the muscle layer and submucosa. Fibroplasia was less visible in the other locations. The presence of eosinophilic granulomatous masses led us to suspect a possible parasitic infection, although some authors note that this pathological condition may have an allergic aetiology.

Animals↗

PubMed1995

Immunocytochemical study of type IV collagen and laminin in canine mammary tumours.

We performed an immunohistochemical study of the basement membrane (BM) proteins laminin and type IV collagen in 35 canine mammary tumours, histologically classified according to the World Health Organization's suggested classification. Laminin and type IV collagen were seen in extracellular locations but only laminin was present in epithelial and myoepithelial cells and chondrocytes. The BM was always continuous in adenomas and fibroadenomas. In the 20 malignant tumours studied, the basement membrane was continuous in one, discontinuous in five, and virtually absent in 14. When present, the BM of malignant tumours varied in width and distribution in the same area. The benign and malignant mixed tumours did not have BM separating epithelial and newly-formed mesenchymal structures. In areas of abundant myoepithelial cells in complex and mixed tumours, both benign and malignant, there were groups of BM fragments which differed in length and thickness and occasionally formed tangles. We have called these 'membranous thickets'. Our results indicate that myoepithelial cells are the main source of the BM proteins laminin and type IV collagen in canine mammary tumours.

Adenocarcinoma↗

PubMed1994

A faster-acting and more potent form of tissue plasminogen activator.

Current treatment with tissue plasminogen activator (tPA) requires an intravenous infusion (1.5-3 h) because the clearance of tPA from the circulation is rapid (t 1/2 approximately 6 min). We have developed a tPA variant, T103N,N117Q, KHRR(296-299)AAAA (TNK-tPA) that has substantially slower in vivo clearance (1.9 vs. 16.1 ml per min per kg for tPA in rabbits) and near-normal fibrin binding and plasma clot lysis activity (87% and 82% compared with wild-type tPA). TNK-tPA exhibits 80-fold higher resistance to plasminogen activator inhibitor 1 than tPA and 14-fold enhanced relative fibrin specificity. In vitro, TNK-tPA is 10-fold more effective at conserving fibrinogen in plasma compared to tPA. Arterial venous shunt models of fibrinolysis in rabbits indicate that TNK-tPA (by bolus) induces 50% lysis in one-third the time required by tPA (by infusion). TNK-tPA is 8- and 13-fold more potent in rabbits than tPA toward whole blood clots and platelet-enriched clots, respectively. TNK-tPA conserves fibrinogen and, because of its slower clearance and normal clot lysis activity, is effective as a thrombolytic agent when given as a bolus at a relatively low dose.

Animals↗

PubMed1994

Personal history, training, and worksite as predictors of back pain of nurses.

Back pain among nurses is a common problem. Prior studies of this problem have been based on cross-sectional or retrospective data. This 18-month prospective study involving nurses newly graduated from nursing school investigated personal, worksite, and training factors associated with future risk of back pain. Each nurse underwent a preliminary interview and periodic follow-ups to identify those with back injuries. Contingency tables and logistic regression analyses demonstrated that prior significant back pain episodes (evidenced by previous job changes because of back pain, frequent medication use, etc.) were associated with increased future risk. Training at nursing school or on the job did not have a protective effect. This pilot study therefore suggests factors useful in placement and counseling of new nurses and indicates the need for further implementation of mechanical lift assist device use.

Accidents, Occupational↗

PubMed1994

Expression of fibronectin and its integrin receptor alpha 5 beta 1 in canine mammary tumours.

Fibronectin and its integrin receptor alpha 5 beta 1 were studied by immunohistochemical methods in five normal canine mammary glands, four dysplastic glands and 18 mammary tumours. The aim of the study was to evaluate the possible changes in the alpha 5 beta 1 integrin receptor and its ligand fibronectin in relation to the metastatic capacity of canine mammary neoplasms. The immunostaining of alpha 5 beta 1 was very uniform in the hyperplastic glands but uneven in the mammary tumours. The expression of alpha 5 and beta 1 was diminished in metastatic tumours but there were some alpha 5-positive cells with pronounced features of malignancy and immaturity. Stromal fibronectin was increased in most cases and cytoplasmic staining of fibronectin was observed in epithelial and myoepithelial cells in mammary neoplasms but not in normal or dysplastic mammary tissue. There was no relationship between the content of alpha 5 beta 1 and the expression of fibronectin in canine mammary tumours.

Animals↗

PubMed1994

Subject-based rating of hand-wrist stressors.

Subject-based rating (SBR) methods (eg, Borg Scales) have been applied to lifting and exertion estimation. SBR methods were applied to hand-wrist motions in this controlled experimental study of rapid motion. Seven normal volunteers performed lift actions with several combinations of wrist position (flexion-extension), repetition frequency, force, and grip type (precision vs power) using an experimental apparatus. Wrist position and frequency were confirmed using an electrogoniometer. Subjects rated the tasks along 5 scales. Analysis showed that grip type had the predominant effect on the subjective ratings, but the other factors were also rated. However, cycle times between 3 and 8 seconds were not well differentiated. The study indicates that SBR does validly reflect actual stressors and suggests that SBR may be useful for "screening" jobs for more intensive study.

Adult↗

PubMed1993

Supermarket checker motions and cumulative trauma risk.

The relationship between specific motions and symptoms consistent with upper extremity cumulative trauma disorders (UECTDs) was investigated in 50 supermarket checkers. Each completed a questionnaire concerning UECTD symptoms; four composite symptom indices were derived: any arm symptoms, hand-wrist-lower arm (S-DIST), upper arm, and symptoms specifically associated with carpal tunnel syndrome (S-SPC). Each participant was videotaped on at least two occasions while performing checking work. Analysis of these tapes assigned each subject a composite motion index for each of the following motions: wrist flexion, wrist extension, body (lumbar) flexion, pronation, grip type, and tendency to lift objects. "Positive" symptom status was defined by a score in the upper quartile for the symptom index. Relationships between an individual's motion indices and symptom indices were analyzed by determining the percent of subjects "positive" for symptoms in each quartile of motion index, by rank correlation, and by regression of symptom scores on principal components of motions. Trends toward relationship of wrist flexion and extension, lumbar flexion, and pronation with S-DIST and S-SPC were noted. Principal components regression confirmed that extension and flexion were related to these two symptom outcomes. This study suggests that postural loading can be determined on an individual basis in a meaningful fashion and that interventions that decrease such loading may be beneficial. It supports the role of certain repetitive motions as causes of UECTD symptoms.

Adult↗

PubMed1993

Tomato necrosis and the 369 nucleotide Y satellite of cucumber mosaic virus: factors affecting satellite biological expression.

To determine which factors can affect biological expression of the Y satellite RNA of cucumber mosaic virus (CMV) in tomato, three laboratories collaboratively exchanged their natural satellite variants, the corresponding recombinant DNA clones and helper virus strains, as well as tomato varieties, on which different observations previously reported were based. The effects of these materials and the influence of temperature on symptom expression were systematically studied. The results show that in a standardized tomato bioassay at 24 degrees C, the Y satellite, when supported by either CMV-1 or CMV-Y, did not induce tomato necrosis in the Rutgers variety but elicited a slower necrotic response in the Best of All variety that was variably lethal, as compared to the faster inevitably lethal response induced by a prototype necrogenic D satellite variant in both tomato varieties. At higher temperatures (26.5 to 32 degrees C) an extremely fast-killing necrosis caused by CMV-Y itself was observed. The study demonstrates that in experiments on virus symptom modulation induced by CMV satellites, the nature of the helper virus, host plant varieties, as well as the environmental conditions should be precisely defined, and the effects of each parameter change determined separately.

Mosaic Viruses↗

PubMed1992

Upper extremity symptoms in supermarket workers.

Upper extremity symptoms in supermarket workers, particularly those who performed checking using laser scanners, were evaluated using a questionnaire administered by trained interviewers to 124 supermarket workers. Summary indices of exposure (short-term and long-term) as well as indices of past personal illnesses and personal activities were employed. Outcome data were summarized by four composite symptom indices. Chi square and logistic regression analyses demonstrated that hours of checking work in the preceding 2 weeks and cumulative weighted years of work were associated with adverse upper extremity symptoms. Symptoms involved both the proximal and distal parts of the upper extremities.

Adult↗

PubMed1992

Immunocytochemical study of the diffuse neuroendocrine system cells in equine lungs.

This study was undertaken to investigate the presence of neuroendocrine cells (N.E.C.) by immunocytochemical means in equine lungs during three distinct evolutionary periods: fetal, neonatal and adult. The authors identified bombesin, somatostatin and calcitonin secretory cells. In the fetal lungs the N.E.C. were located in the interstitial tissue and exhibited greater immunoreactivity to bombesin than to the other two neuropeptides studied. A large number of calcitonin-producing cells and a smaller number of bombesin-positive cells were seen in the bronchial and bronchiolar epithelium of newborn Equidae. In the adult equine lungs far fewer N.E.C. were observed than in the earlier stages. Somatostatin-producing cells were not seen in neonatal or adult lung tissue.

Animals↗