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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

[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↗
PubMed1995

Coloanal anastomosis: are functional results better with a pouch?

PURPOSE: Different studies have shown that low colorectal and coloanal anastomosis often yield poor functional results. The aim of the present study was to investigate whether a colonic reservoir is able to improve functional results. METHODS: Thirty-eight consecutive patients subjected to low anterior resection were randomized following rectal excision in two groups. One (n = 19) had a stapled straight coloanal anastomosis, and the other (n = 19) had a 10-cm stapled colonic pouch low rectal anastomosis. Median anastomotic distance above the anal verge was 3.38 +/- 0.56 cm and 2.14 +/- 0.36 cm in both groups, respectively. Continence alterations, urgency, tenesmus, defecatory frequency, anal resting and maximum voluntary squeezing pressures, and maximum tolerable volume were evaluated one year later. RESULTS: One patient died of pulmonary embolism, and seven presented with a recurrence and were excluded from the study. Stool frequency was greater than three movements per day in 33.3 percent of cases with a reservoir and in 73.3 percent of those with a straight coloanal anastomosis (P < 0.05). Maximum tolerable volume was significantly greater in patients with a reservoir (335 +/- 195) than in those without (148 +/- 38) (P < 0.05). There were no significant differences in other variables studied. CONCLUSIONS: This study shows that some aspects of defecatory function after rectal excision could improve with a colonic reservoir.

Aged↗
PubMed1995

Influence of joint laxity on scaphoid kinematics.

Excessively lax wrists more frequently become symptomatic if overloaded or injured than normal joints. Whether this is the consequence of biological or mechanical factors or both remains unknown. This study evaluates the relationship between the degree of joint laxity and scaphoid kinematic behaviour during radio-ulnar deviation of the wrist in 60 normal volunteers. There is a significant linear relationship between the direction of scaphoid rotation and the amount of wrist joint laxity. During lateral deviation of the wrist, joints that are more lax have a scaphoid rotating mainly along the sagittal plane of flexion and extension, with little lateral deviation. In contrast, the scaphoid of volunteers with decreased laxity rotate mostly along the frontal plane of radioulnar deviation with minimal flexion extension. These results support the concept of increased out-of-plane scaphoid rotation as a factor of increased vulnerability during over-work or injury.

Adult↗
PubMed1995

Fibroblast responses to cytokines are maintained during aging.

Impaired wound healing in older individuals may result from a global deficit of fibroblast activity or a decreased response of aged fibroblasts to stimulation by inflammatory cytokines. Twenty-eight fibroblast cell strains were developed from normal human skin aged 3 days to 84 years. Mitogenic response to cytokines, epidermal growth factor, tumor necrosis factor-alpha, platelet-derived growth factor or fetal bovine serum was determined using a 4-hour 3H-thymidine incorporation assay. Synthesis of collagen and noncollagen proteins was determined basally and in response to transforming growth factor-beta using a 6-hour 3H-proline incorporation assay. Neither the mitogenic response to cytokine stimulation (p > 0.3) nor the synthesis of collagen and noncollagen protein after transforming growth factor-beta stimulation (p > 0.4) varied with the age of the cell donor. Individual cell lines' response to cytokine stimulation varied widely, reflecting differences commonly seen in patients' wound-healing abilities. Cellular responses to wound-healing cytokines are preserved as people age. Abnormalities in wound healing in older patients may be the result of altered immune initiation of healing or the cumulative result of concomitant disease.

Adolescent↗
PubMed1995

Primary lymphoma of the liver mimicking metastatic liver disease.

Primary lymphoma of the liver is rare. In the 50 previously reported cases in the literature, computed tomography usually showed a solitary, bulky hypodense area in the liver. We report a case of primary lymphoma of the liver presenting multiple lesions in the liver and clinical and biochemical evidence suggestive of metastatic adenocarcinoma of the liver.

Adenocarcinoma↗