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Biomedical subjects

L Contreras

Publications and source records attributed to L Contreras.

At least 37 records · Page 2Linked to original sources
PubMed1994

Macrophage response to experimental implantation of polypropylene prostheses.

We have assessed the macrophage response to polypropylene mesh (Marlex) implanted into the abdominal wall of New Zealand white rabbits, using RAM-11, a monoclonal antibody specific for rabbit macrophages. The response diminishes during the course of the first 90 days after implantation, although the presence of other cell types typical of foreign-body reactions increases. We have also confirmed the high degree of integration of the biomaterial into the wall achieved after 9 weeks. This has been determined using light and scanning electron microscopy. Likewise, we have observed the formation of numerous adhesions between the polypropylene mesh and the viscera of the abdominal cavity.

Animals↗
PubMed1994

[Non ulcerative dyspepsia: relationship of symptomatology, gastritis and Helicobacter pylori].

BACKGROUND: histological alterations of gastric mucosa and its colonization by Helicobacter pylori are postuled to be implicated in the pathogenesis of non ulcer dyspepsia. AIM: to study the possible relationships between histological gastritis and Helicobacter pylori in non ulcer dyspepsia symptomatology. PATIENTS AND METHODS: fifty four patients (39 females) with non ulcer dyspepsia whose ages ranged from 17 to 68 years were subjected to an upper GI endoscopy with gastric mucosa biopsy samples for histological study and microbiological identification of Helicobacter pylori. Gastrointestinal complains were blindly quantified using a scored questionnaire. RESULTS: thirty one subjects (57.4%) had Helicobacter pylori in their gastric mucosa. There was acute inflammatory activity in 26 of the 31 patients with Helicobacter pylori (81%) and 15 of 23 without Helicobacter (65%). The median score of symptoms was 7 (range 2-13) in patients with Helicobacter and 6 (range 2-10) in patients without Helicobacter. CONCLUSIONS: there were no significant differences in gastric mucosa acute inflammatory activity and non ulcer dyspepsia symptomatology between patients with or without Helicobacter pylori colonization of gastric mucosa.

Adolescent↗
PubMed1993

Modulation of proliferation kinetics in human squamous cell carcinomas of the head and neck.

OBJECTIVE: Proliferation of tumor clonogens during a course of conventional head and neck radiotherapy serves to compromise ultimate tumor control. Biologic strategies that attempt to alter tumor proliferation kinetics using cytostatic or antiproliferative agents may therefore prove valuable by limiting tumor cell repopulation during therapy. DESIGN: Three human squamous cell carcinoma (SCC) cell lines, derived from primary head and neck cancers, have been characterized in vitro via flow cytometric analysis of proliferation kinetics, and in vivo via tumor xenograft growth evaluation in athymic mice. RESULTS: The antiproliferative agent alpha-difluoromethylornithine (DFMO), an inhibitor of polyamine biosynthesis, induced growth inhibition of these SCCs in culture and when administered orally to athymic mice harboring SCC tumor xenografts. Cell cycle kinetic analysis via flow cytometry revealed that DFMO induced a lengthening of in vitro tumor cell potential doubling times. Similarly, DFMO administered continuously via the drinking water to athymic mice harboring human SCC xenografts induced a prolongation of in vivo tumor volume doubling. CONCLUSIONS: These data indicate that biologic agents, such as DFMO, can alter SCC growth kinetics and may prove useful in designing new therapeutic strategies for rapidly proliferating tumors such as those that occur in the head and neck.

Animals↗
PubMed1993

[Breast biopsy with fine needle. Evaluation of a new method].

A new methodology to obtain tissue samples from breast tumors through fine needle aspiration is described. This consists of a screwdriver like movement of the needle and continuous aspiration. The tissue is embedded in a blood clot, fixed in 10% formalin and routinely processed for histopathological study. From March 1987 to March 1990 this technique was applied in 84 patients. Ten did not have conventional histopathological study. The 74 patients studied had 76 tumors. Six cases (7.9%) had "unsatisfactory" specimens and nine (11.8%) only allowed cytological diagnosis. The 61 remaining samples (80.3%) were considered "sufficient" for histopathological study. The new methodology had a sensitivity of 95.5% specificity of 100% and positive predictive value of 100%. In this series there were no false positive cases.

Adult↗
PubMed1992

Restoration of malonyl-CoA sensitivity of soluble rat liver mitochondria carnitine palmitoyltransferase by reconstitution with a partially purified malonyl-CoA binding protein.

Solubilization of rat liver mitochondria in 5% Triton X-100 followed by chromatography on a hydroxylapatite column resulted in the identification of malonyl-CoA binding protein(s) distinct from a major carnitine palmitoyltransferase activity peak. Further purification of the malonyl-CoA binding protein(s) on an acyl-CoA affinity column followed by sodium dodecyl sulfate gel electrophoresis indicated proteins with Mr mass of 90 and 45-33 kDa. A purified liver malonyl-CoA binding fraction, which was devoid of carnitine palmitoyltransferase, and a soluble malonyl-CoA-insensitive carnitine palmitoyltransferase were reconstituted by dialysis in a liposome system. The enzyme activity in the reconstituted system was decreased by 50% in the presence of 100 microM malonyl-CoA. Rat liver mitochondria carnitine palmitoyltransferase may be composed of an easily dissociable catalytic unit and a malonyl-CoA sensitivity conferring regulatory component.

Animals↗
PubMed1991

Patterns of electromyographic activity in subjects with different skeletal facial types.

Integrated electromyographic activity of masseter and anterior temporal muscles was recorded using bipolar surface electrodes in 33 young adults. Subjects were skeletally classified according to ANB angle reading corrected both for maxillary position and rotation of the jaw. Postural activity for both muscles was higher in Class III subjects than in Class I and Class II, whereas in Class I and II subjects activity was similar. During swallowing, masseter muscle activity in Class III subjects was higher than Classes I and II, whereas anterior temporal muscle activity was not different between Classes III and I. During maximal voluntary clenching, activity was not different among classes. High correlations between electromyographic activity and corrected ANB angle as well as with overjet were observed. Skeletal classification used in the present study may have clinical relevance regarding treatment and prognosis, as well as in the assessment of the relationship between muscular activity and craniofacial characteristics.

Adolescent↗
PubMed1991

[Epidemiology of fractures in Chile].

Bone fractures represented 3.3% of diagnosis among 1,003,267 patients discharged from National Health System Hospitals in Chile during 1985. Among 73,534 certified deaths, 1.2% followed fractures. Significantly higher rates were observed in males; after age 75, fractures were more common in females. Rates per 100,000 for different fractures were: radio-cubital 45.4, shine and fibula 41, ankle 28.1, humerus 25.3, and hip 23.5. Among males the figures were shine and fibula 66.2, radius and cubitus 64.9, face 37.5 and ankle 37.1. Among females, hip 28.2, radius and cubitus 26.3, ankle 19.3 and humerus 16.5. Hip fracture is clearly related to age, the incidence raising from below 60 per 100,000 under age 60 to 617 in females and 330 in males above that age. Other fractures that increase with age include radius and cubitus, shine and fibula, ankle, humerus and femur.

Adolescent↗
PubMed1991

[Neurologic involvement in Reiter's disease. Report of 2 cases].

Neurologic involvements is a rare complication of Reiter syndrome. It may precede other manifestations and constitutes a cause of death. We report 2 cases. The first, an 18 year-old male developed arthritis, fever, balanitis and sacroileitis 2 months after non gonococcal urethritis. He received phenylbutazone and local steroids without improvement. Logic dysphagia, diplopia with bilateral paralysis of the IV and VI cranial nerves and generalized absent reflexes developed gradually 2 weeks after admission. Methylprednisolone pulses failed to improve the patient's condition and plasmapheresis was associated to near complete remission after 6 exchanges. The other patient, a 31 year old male started out with alternating lower extremity paresis. One month later, urethritis, conjunctivitis, arthritis and sacroileitis appeared. The electromyogram was characteristic of axon sensorimotor polyneuropathy. Administration of naproxen was associated to complete improvement within 2 weeks. Neither patient had shown evidence of recurrence after a 5 year follow up period.

Adolescent↗
PubMed1990

Characterization of a low molecular weight protein of the ATP synthetase complex from beef heart and rat liver mitochondria with a high affinity monoclonal antibody.

A monoclonal antibody raised against beef heart mitochondria elicited a strong reaction on Western Blot with a 16 kD protein in preparations of beef heart mitochondria, ammonia particles, oligomycin sensitive ATPase and Complex V, in addition to showing a lesser affinity for the partially purified 30 kD ADP/ATP carrier. The antibody also reacted with a 17 kD protein in rat liver mitochondria and an enriched membrane vesicle fraction. The N-terminal sequence of the first twenty amino acids of both the beef heart and rat liver proteins contained significant homology. Comparison with results in the literature indicate that the proteins represent the delta subunit of the ATP synthetase complex. Further evidence suggests that the epitope for the antibody may reside at the C-terminal 30-40 amino acid residues of both proteins.

Amino Acid Sequence↗
PubMed1989

Photoaffinity labeling of hamster brown adipose tissue mitochondria by an [125I] coenzyme A derivative: differential interaction with the uncoupling protein and ADP/ATP carrier.

We have recently synthesized an azido [125I] CoA photolabel, N-(3-iodo-4-azidophenyl propionamide) cysteinyl-5-(2'thiopyridyl cysteine) CoA that specifically labeled the ADP/ATP carrier in beef heart mitochondria. In this study brown adipose tissue mitochondria were photolabeled with the azido [125I] ACT-CoA derivative with or without inhibitors. SDS gel electrophoresis and autoradiography of the separated proteins revealed exclusive photolabeling of two polypeptides corresponding to the ADP/ATP carrier and uncoupling protein. In the presence of carboxyatracytloside only the 32 kD UCP was labeled by [125I] ACT-CoA, whereas preincubation with GDP resulted in exclusive photolabeling of the 30 kD ADP/ATP carrier. Palmitoyl CoA but not palmitic acid inhibited photolabeling of both polypeptides.

Acyl Coenzyme A↗
PubMed1986

Reliable serology of Taenia solium cysticercosis with antigens from cyst vesicular fluid: ELISA and hemagglutination tests.

New levels of reproducibility and sensitivity have been achieved in the detection of anticysticercus antibodies in human sera by using cysticercus vesicular fluid as the source of antigens for both ELISA and hemagglutination assays. Reproducibility both between tests on a serum and between similar sera was significantly improved over typical results using antigens from whole parasite extracts. Sera collected from uninfected individuals in endemic areas gave somewhat elevated values over those collected in nonendemic areas. This necessitated the use of a higher threshold in endemic areas to avoid false positives. With the threshold appropriate for a nonendemic area, both ELISA and hemagglutination were sensitive enough to detect infection in 95% of cases. With the threshold value for sera from an endemic area, these sensitivities were reduced to 80%-90%. A prominent 103-Kd protein of vesicular fluid, not related to antigen B, elicited the strongest antibody response in neurocystercotic patients.

Antibodies↗
PubMed1982

Gastricsin and cathepsin D in normal and hypertrophic human prostates.

The relative contents of gastricsinogen, the inactive zymogen precursor of gastric gastricsin (EC 3.4.23.3), and cathepsin D (EC 3.4.23.5) in normal and benign hyperplasia of the prostate gland have been determined. Gastricsinogen levels are significantly lower (0.116 +/- 0.02 U/gm. wet tissue) in the hyperplastic than in normal prostates (0.65 +/- 0.06 U/gm.). Conversely, cathepsin D levels are higher in the diseased (0.705 +/- 0.17 U/gm.) as opposed to normal prostatic tissue (0.39 +/- 0.12 U/gm.). The average gastricsin-cathepsin D differences between the 2 tissues (0.26 +/- 0.025 for normal prostates and -0.59 +/- 0.057 SEM for hyperplastic tissue) are also significantly different (p less than 0.001). It is suggested that the simple determination of these 2 acid proteinases in prostate homogenates could be used as alternative and complementary marker enzymes for the study of the physiopathologic status of the prostate gland.

Acid Phosphatase↗
PubMed1980

Splenic abscess.

Fourteen cases of splenic abscess are reported and 159 cases previously cited in the literature are reviewed. The incidence, predisposing factors, pathogenesis, clinical features, bacteriology and radiologic findings are discussed. Infective endocarditis was the most common single antecedent infection. Hemoglobinopathies, non-penetrating abdominal trauma, and gastrointestinal malignancy appear to predispose the spleen to abscess formation. Emphasis is placed on clinical features and radiologic findings to aid practitioners in diagnosing this uncommon but often fatal infection. Also emphasized is the necessity for prompt surgical intervention when splenic abscess is suspected. An approach to the antimicrobial therapy in different clinical settings is outlined.

Abscess↗