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Biomedical subjects

J Rodriguez

Publications and source records attributed to J Rodriguez.

At least 127 records · Page 7Linked to original sources
PubMed1996

Cytogenetic Monitoring of Farmers exposed to pesticides in Colombia.

We have monitored 30 pesticide-exposed workers and 30 matched controls for expression of chromosome aberrations (CA) and sister chromatid exchanges (SCE) in their lymphocytes. Peripheral blood cultures were set up within 3 hr after the collection of samples, and four cultures were set up from each donor. For CA analysis, 100 complete metaphase cells from each donor were evaluated. For the SCE assay, 50 complete metaphase cells from each donor were analyzed. The CA and SCE data were analyzed for differences between the two groups using the chi 2 and the Student's t-test, respectively. From the CA analysis it was obvious that the overwhelming majority of aberrations were chromatid breaks and isochromatid breaks; therefore, only these data are presented and used for statistical analysis. Isochromatid breaks were counted as two breaks each and chromatid breaks as one in calculating the total chromatid break frequencies. Statistical evaluation of the data indicates that there is no significant difference (p > 0.05; chi 2 test) between the exposed and the nonexposed groups based on chromatid breaks per 100 cells (1.2 +/- 0.3 and 1.5 +/- 0.2, respectively) and total chromatid breaks per 100 cells (1.7 +/- 0.3 and 2.1 +/- 0.2, respectively). No significantly difference between the two groups (p > 0.05, Student's t-test) was observed with SCE frequencies (5.0 +/- 1.1 and 4.8 +/- 0.9, respectively). Linear regression analysis indicates that the data were not influenced by age, cigarette smoking, or alcohol consumption. It is assuring that the exposure conditions among these Indian farmers have not caused detectable increases of chromosome damage using standard assays; this suggests the lack of serious long-term health problems. However, periodic monitoring of such exposed populations should be conducted using the same or other more sensitive assays. In addition, other populations with exposure to different types of pesticides in Colombia should also be investigated.

Adolescent↗
PubMed1996

Variation in the response of T cells to concanavalin A after in vitro exposure to benzo[A]pyrene and 2-aminofluorene.

The ability of the polycyclic aromatic hydrocarbon (PAH), benzo[a]pyrene (BP) and its metabolites to be immunosuppressive has been well documented by many investigators. The arylamine, 2-aminofluorene (AF) and its metabolic intermediates have not been as widely studied in this regard. Here, we investigate the effect of BP, 3-hydroxy-BP (3-OH-BP), AF, N-hydroxy-AF (N-OH-AF) and acetyl-AF (AAF) on T-cell proliferation using the T-cell mitogen, Concanavalin A (ConA). These compounds as well as BP-7, 8-diol-9, 10-epoxide (BPDE) were also used to determine their effect on T-cell-mitogen binding. Both AF and BP are substrates for the P-450 and flavin-containing monooxygenase enzyme system, which can be induced with beta-naphthoflavone (beta NF). We incubated beta nF with BP and AF to determine the effect of a P-450 inducer on BP and AF mediated-ConA suppression. Here we demonstrate that BP, 3-OH-BP, AF, and AAF are able to suppress the proliferative response to ConA, while N-OH-AF cannot. Further, we show that BP, 3-OH-BP, BPDE, AF and N-OH-AF do not alter the ability of ConA to bind the mitogen receptor of splenic T-cells, indicating an intracellular mechanism for suppression. Studies with beta NF indicate that this P-450 inducer enhances the anti-proliferative effect of BP, while it abolishes this effect of AF.

Animals↗
PubMed1996

Endocrine characterization of primary mediastinal lymphoma.

Because of the characteristic presentation of primary mediastinal large cell lymphoma (PMLCL) in young females its known origin from thymic B-cells, there might be a role in lymphomagenesis for estrogen receptors as well as for known neuroendocrine thymic mediators. A retrospective review of all patients with diffuse large cell lymphoma seen at our institution from January 1985 to January 1994 revealed 75 consecutive cases with a diagnosis of PMLCL. Through retrieval from our pathologic archives and requests to outside pathologists, we recovered and analyzed 17 biopsy specimens for the presence of the following hormone receptors: estrogen, beta endorphin, prolactin, T3, growth hormone, and leutinizing hormone. None of the specimens stained for any of the reagents. The most plausible explanation is that PMLCL tissues are devoid of these hormonal receptors and thus these receptors do not seem to play a role in the pathogenesis of PMLCL.

Biopsy↗
PubMed1996

Serological reactivity to a synthetic analog of phenolic glycolipid I and early detection of leprosy in an area of low endemicity.

A total of 23,863 individuals living in an area of low endemicity for leprosy were tested by enzyme-linked immunosorbent assay with a semisynthetic analogue of the phenolic glycolipid I antigen of Mycobacterium leprae. The proportion found positive was 3.86% which was significantly higher than that in a sample of a population known to be free of leprosy. Clinical examinations as well as Mitsuda and skin smear tests were organized for those defined as seropositive. The proportion of individuals with lepromin reactions of less than 3 mm increased 18.9% per serological interval as antibodies rose though it was not statistically significant. As a result of the clinical and bacteriological examinations, 2 cases with clinical signs and heavy bacillary load were found, whereas acid-fast bacilli were demonstrated in 2 other individuals without clinical manifestations of leprosy. The usefulness of the system for control purposes is discussed.

Adolescent↗
PubMed1996

[Surgery of the hypopharynx after radiotherapy].

Changes in surgical procedures for hypopharynx cancer after definitive radiotherapy are important since the use of pedicled myocutanous flaps and free digestive transplants. Postoperative course is improved and salvage surgery more frequent. From 1970 to 1990, 160 hypopharyngeal carcinomas were operated on after radiotherapy, 103 due to failures or complications after definitive irradiation and 57 metachronous cancers. During this period, the rate of lethal postoperative complications decreased from 25% to 8%. Crude survival rates are 51% at 1 year, 22% at 3 years and 15% at 5 years. Poor prognostic features are local extension, positive margins and extracapsular nodal spread. Postoperative deaths and failures in primary or neck account for 60% of the causes of death. Results of salvage surgery are unsatisfactory: the choice of definitive radiotherapy with surgery in reserve must be restricted to selected cases.

Aged↗
PubMed1996

[Surgery of the oropharynx after radiotherapy].

Over 40 years after the first commando procedures performed by M Dargent, surgical techniques such as mandibulotomy and myocutaneous flaps yield important changes in oropharyngeal surgery after definitive radiotherapy. Wide resections and simultaneous neck dissection are possible with good functional results. From 1970 to 1990, 250 patients with a carcinoma of the oropharynx were operated on after radiotherapy, 163 because of failure or complication of irradiation, 87 for a metachronous carcinoma occurred in an previously irradiated field. The postoperative mortality rate was 6%. The risk of carotid blow-up did not increase with the extension of the resection. Survival rates at 1, 3 and 5 years are 55%, 22%, 16% in salvage surgery and 69%, 36% and 24% in patients with metachronous cancer. Postoperative complications and failures in the primary and/or the neck account for 60% of causes of death. These results suggest that prior surgery of deeply ulcerative carcinoma of the oropharynx followed by radiotherapy is a better strategy than definitive radiotherapy with salvage surgery in reserve.

Aged↗
PubMed1995

Prognostic value of tumor regression during radiotherapy for head and neck cancer: a prospective study.

OBJECTIVE: Prospective evaluation of tumor regression during external irradiation for head and neck squamous cell carcinomas and its association with long-term local control. METHODS AND MATERIALS: Two hundred twenty-eight patients with histologically confirmed squamous cell carcinoma [oral cavity: 59 (26%), oropharynx: 65 (29%), hypopharynx: 37 (16%), larynx: 67 (29%)] were included between January 1986 and December 1990. Curative intent external irradiation delivered 65-70 Gy over a period of 7 weeks (five 2 Gy fractions per week). Tumor regression was evaluated clinically and endoscopically every week. RESULTS: Tumor regression, assessed at 2 weeks, was as follows: no response: 62 (30%), 25% response: 121 (59%); 50% response: 23 (11%). At 5 weeks, 9 (4%) patients showed 0-25% regression, 75 (33%) showed 50% regression, 115 (50%) showed 75% regression, and 29 (13%) showed complete regression. Median follow-up was 79 months (range: 6-96 months). The local control probability was 68% (62-74%) at 2 years, 65% (59-70%) at 5 years. Univariate analysis showed that, at 2 weeks, local control was significantly different between the nonresponders and the patients with 25% or greater response (p < 0.025) and that, at the fifth week, local control was very different between the major responders (75 and 100%) and the minor responders (0-50%) (p < 0.0001). Multivariate analysis (Cox Proportional Hazards Model) showed that the probability of local relapse was significantly and independently increased for minor regression at 5 weeks [Relative risk (RR) of failure was 2.3 (1.4-3.7)], for nonlaryngeal tumors [RR: 2.4 (1.3-4.5)], and for Stage T3-T4 [RR:2.4 (1.4-4)]. Three prognostic groups can, therefore, be proposed: 1) low risk of recurrence when regression > or = 75% and laryngeal tumor or T1-T2 tumors in other sites: 106 (46.5%) patients, 2-year local control probability: 84% (77-92%); 2) high risk of recurrence: regression < or = 50% and T3-T4 nonlaryngeal tumors: 44 (19%) patients, 2-year local control probability: 27% (13-41%); 3) intermediate risk of recurrence: 78 (34.5%) patients, 2-year local control probability: 69% (58-80%). CONCLUSION: The present study suggests that tumor regression during external radiotherapy is an independent predictive factor of local control in head and neck carcinomas.

Carcinoma, Squamous Cell↗
PubMed1995

Role of ligaments and facets in lumbar spinal stability.

STUDY DESIGN: The issue of segmental stability using finite element analysis was studied. Effect of ligament and facet (total and partial) removal and their geometry on segment response were studied from the viewpoint of stability. OBJECTIVES: To predict factors that may be linked to the cause of rotational instabilities, spondylolisthesis, retrospondylolisthesis, and stenosis. SUMMARY OF BACKGROUND DATA: The study provides a comprehensive study on the role of facets and ligaments and their geometry in preserving segmental stability. No previous biomechanical study has explored these issues in detail. METHODS: Three-dimensional nonlinear finite element analysis was performed on L3-L4 motion segments, with and without posterior elements (ligaments and facets), subjected to sagittal moments. Effects of ligament and facet (partial and total) removal and their orientations on segment response are examined from the viewpoint of stability. RESULTS: Ligaments play an important role in resisting flexion rotation and posterior shear whereas facets are mainly responsible for preventing large extension rotation and anterior displacement. Facet loads and stresses are high under large extension and anterior shear loading. Unlike total facetectomy, selective removal of facets does not compromise segmental stability. Facet loads are dependent on spatial orientation. CONCLUSIONS: Rotational instability in flexion or posterior displacement (retrospondylolisthesis) is unlikely without prior damage of ligaments, whereas instability in extension rotation or forward displacement (spondylolisthesis) is unlikely before facet degeneration or removal. The facet stress and displacement distribution predicts that facet osteoarthritis or hypertrophy leading to spinal stenosis is most likely under flexion-anterior shear loading. Selective facetectomy may restore spinal canal size without compromising the stability of the segment. A facet that is more sagittally oriented may be linked to the cause of spondylolisthesis, whereas a less transversely oriented facet joint may be linked to rotational instabilities in extension.

Biomechanical Phenomena↗
PubMed1995

[Management of laryngeal cancers].

With 5,000 cases yearly, laryngeal carcinomas account in France for the third of squamous cell cancers of the upper digestive and respiratory tract. The crude survival rate is 50% at 5 years. Carcinomas of vocal cords are often diagnosed as early stages if dysphonia leads the patients to the ENT specialist within 2 weeks. Cure of the primary is achieved in 90% of the early stages by radiotherapy with narrow fields or partial surgery, with a 80% 5 years survival rate. Advanced tumors are often treated by total laryngectomy and postoperative radiotherapy. Supra-glottic cancers (epiglottis) are more serious. Unilateral dysphagia or upper cervical neck node often delay early diagnosis. A total laryngectomy is the commonest treatment. The 5 years survival rate of 40% is due to local and/or regional failures and metachronous cancers in head and neck, and radiotherapy remains the two major treatments. Primary prevention is based upon suppression of tobacco and reduction of alcoholic consumption, secondary prevention on resection of leucoplakia and close follow-up of patients with chronic laryngitis.

Humans↗
PubMed1995

Characterization of the invertase from Pichia anomala.

Synthesis of invertase (EC 3.2.1.26) in Pichia anomala is controlled by the carbon source in the culture medium. The enzyme was purified to homogeneity from P. anomala cells fully derepressed for invertase synthesis and shown to be a multimeric glycoprotein composed of identical subunits with an apparent molecular mass of 86.5 kDa. The carbohydrate moiety accounts for approx. 30% of the total mass of the molecule and consists of manno-oligosaccharides N-linked to the polypeptide. Most of the characteristics of the enzyme analysed in this study were similar to those previously reported for other yeast invertases, with the remarkable exception of its thermal sensitivity which appears after 15 min incubation at temperatures above 32 degrees C.

Carbohydrates↗
PubMed1995

Effects of protein kinase C modulation on NMDA receptor mediated regulation of neurotransmitter enzyme and c-fos protein in cultured neurons.

The role of protein kinase C (PKC) in N-methyl-D-aspartate (NMDA) receptor-mediated biochemical differentiation and c-fos protein expression was investigated in cultured cerebellar granule neurons. The biochemical differentiation of glutamatergic granule cells was studied in terms of the specific activity of phosphate-activated glutaminase, an enzyme treatment in the synthesis of the putative neurotransmitter pool of glutamate. When the partially depolarized cells were treated with NMDA for the last 1 to 3 days (between 2 and 5 days in vitro), it elevated the specific activity of glutaminase. In contrast, NMDA had little effect on the activity of aspartate aminotransferase or of lactate dehydrogenase. Treatment of 10-day old granule neurons with NMDA also resulted in a marked increase in the immunocytochemically measured expression of c-fos protein. The increases in both the activity of glutaminase and the steady state level of c-fos protein were specific to the activation of NMDA receptors, as they were completely blocked by D,L-2-amino-5-phosphonovaleric acid. The specific stimulation of NMDA receptors in PKC-depleted granule neurons or in the presence of reasonably specific PKC inhibitors also produced significant elevation in the activity of glutaminase and the expression of c-fos protein. These increases were similar in magnitude to those observed in the granule neurons of the respective control groups. Our findings demonstrate that PKC is not directly involved in the NMDA receptor-mediated signal transduction processes associated with biochemical differentiation and c-fos induction in cerebellar granule neurons.

Animals↗