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J Roy

Publications and source records attributed to J Roy.

At least 73 records · Page 4Linked to original sources
PubMed1997

Role of tyrosine kinases in extracellular matrix-mediated modulation of arterial smooth muscle cell phenotype.

Fibronectin (FN) promotes the modulation of freshly isolated arterial smooth muscle cells (SMCs) from a contractile to a synthetic phenotype by interacting with integrins on the cell surface. This process is characterized by a structural and functional transformation of the cells, including a reorganization of the cytoskeleton, the formation of a large secretory apparatus, and the acquisition of proliferative capacity. In this study we have investigated the role of integrin signaling through tyrosine kinases in the structural changes that occur in SMCs during primary culture on FN. A gradual increase in phosphotyrosine staining in focal adhesions and a concomitant increase in tyrosine phosphorylation of proteins including focal adhesion kinase were observed. In contrast, cells seeded on laminin formed few focal adhesions, and tyrosine phosphorylation of proteins was less than in cells cultured on FN. Treatment of cells cultured on FN with the tyrosine kinase inhibitor genistein strongly suppressed focal adhesion formation, cell spreading, and cytoskeletal reorganization. In addition, electron microscopic analysis demonstrated that the phenotypic modulation was slowed down. These results indicate that the ability of extracellular matrix components to promote a change in the phenotypic properties of SMCs depends on the assembly of focal adhesions with associated tyrosine kinase activity.

Actins↗
PubMed1997

Phenotypic modulation of smooth muscle cells after arterial injury is associated with changes in the distribution of laminin and fibronectin.

Earlier in vitro studies suggest opposing roles of laminin and fibronectin in regulation of differentiated properties of vascular smooth muscle cells. To find out if this may also be the case in vivo, we used immunoelectron microscopy to study the distribution of these proteins during formation of intimal thickening after arterial injury. In parallel, cell structure and content of smooth muscle alpha-actin was analyzed. The results indicate that the cells in the normal media are in a contractile phenotype with abundant alpha-actin filaments and an incomplete basement membrane. Within 1 week after endothelial denudation, most cells in the innermost layer of the media convert into a synthetic phenotype, as judged by loss of actin filaments, construction of a large secretory apparatus, and destruction of the basement membrane. Some of these cells migrate through fenestrae in the internal elastic lamina and invade a fibronectin-rich network deposited on its luminal surface. Within another few weeks a thick neointima forms, newly produced matrix components replace the stands of fibronectin, and a basement membrane reappears. Simultaneously, the cells resume a contractile phenotype, recognized by disappearance of secretory organelles and restoration of alpha-actin filaments. These findings support the notion that laminin and other basement membrane components promote the expression of a differentiated smooth muscle phenotype, whereas fibronectin stimulates the cells to adopt a proliferative and secretory phenotype.

Actins↗
PubMed1997

Markers of radioresistance in squamous cell carcinomas of the head and neck: a clinicopathologic and immunohistochemical study.

PURPOSE: The lack of accurate criteria to predict the response to radiotherapy for individual patients with squamous cell carcinoma of the head and neck (HN-SCC) remains a major problem. The purpose of this study was to investigate the role of several biologic tumor markers to complement clinical prognostic factors in the assessment of response to radiotherapy in SCCs. PATIENTS AND METHODS: p53, ki-67, c-erb B-2, heat-shock protein-27 (HSP-27), and glutathione S transferase (GSTpi) were evaluated by immunohistochemistry on biopsies from 101 patients treated for head and neck cancer by radical radiotherapy. Expression of each marker was correlated with local control and survival using Kaplan-Meier curves. A Cox regression multivariate analysis was also performed that included all clinical and immunohistochemical variables. RESULTS: Expression of p53 and low cell proliferation allowed identification of patients whose tumors did not respond to radiation. Patients with p53-expressing tumors displayed a relative risk (RR) of 3.78 for not being controlled by radiotherapy compared with patients with p53-negative tumors. For tumors with a high growth fraction (ki-67 > 20%) the RR was 0.25 compared with tumors with a low growth fraction (ki-67 < 20%). When p53 expression and cell proliferation were considered simultaneously in a Cox model, the association with resistance to radiation was significant (P = .000004). The RR for resistance with one (p53 staining or ki-67 < 20%) or two (p53 staining and ki-67 < 20%) unfavorable markers was, respectively, 3.8 and 14.87. CONCLUSION: Patients whose tumor expressed p53 with low growth fraction (ki-67 < 20%) had a strong probability not to respond to radiation therapy. Similarly, absence of p53 expression with a high cell proliferation predicted an excellent outcome after radiotherapy even for patients with advanced disease. Prediction of the outcome of radiotherapy would eventually facilitate the early choice of an adequate treatment.

Adult↗
PubMed1997

Rapid screening of marketed paracetamol tablets: use of thin-layer chromatography and a semiquantitative spot test.

Evaluated is the use of thin-layer chromatography (TLC) to determine the quality of paracetamol tablets marketed in Bangladesh. The procedure was carried out using a cheap and rapid TLC method developed by the U.S. Food and Drug Administration. Reported also is a semiquantitative specific spot test for screening paracetamol tablets. The results obtained indicate that, of the 38 brands tested, three were spurious, while 11 were of borderline quality. In some cases, the results were also verified using the British Pharmacopoeia method. The simplified tests described in this article cannot replace the British Pharmacopoeia or U.S. Pharmacopoeia methods but can be employed as initial screening tests.

Acetaminophen↗
PubMed1997

Expression of caveolae on the surface of rat arterial smooth muscle cells is dependent on the phenotypic state of the cells.

Both after vascular injury and when established in vitro, arterial smooth muscle cells pass through a characteristic change in phenotype. This process includes a prominent structural reorganization with partial loss of myofilaments and formation of a large endoplasmic reticulum and Golgi complex. As a result, the cells lose their contractility and become able instead to divide and to secrete extracellular matrix components. In the present study, the expression of plasma membrane caveolae in rat arterial smooth muscle cells was studied in primary culture and during the formation of neointimal thickenings after balloon injury. Electron microscopic analysis revealed that the number of caveolae (identified as flask-shaped invaginations of the plasma membrane) was reduced when the cells converted from a contractile to a synthetic phenotype (as defined morphologically) and then increased again when they readopted a more differentiated state. However, immunoblotting analysis did not show any changes in the cellular content of caveolin (a major protein component of caveolae) during the 1st week in culture. At the same time, immunocytochemical staining demonstrated a shift in the localization of caveolin from small spot-like structures dispersed over the cell surface to vesicular structures in the perinuclear cytoplasm. These findings indicate that the transition of smooth muscle cells from a contractile to a synthetic phenotype involves a marked decline in the number of plasma membrane caveolae. In parallel, caveolin is internalized and redistributed to Golgi-associated vesicles in the perinuclear cytoplasm. In context of the rapidly increasing awareness of the importance of caveolae both in signal transduction and intracellular cholesterol transport, it seems likely that the variations in the number of caveolae may be significant for the functional differences between smooth muscle cells in different phenotypes.

Animals↗
PubMed1996

Low risk of perioperative infection without prophylactic antibiotics for transperineal prostate brachytherapy.

PURPOSE: To determine the incidence of postimplant infection in patients who are not given prophylactic antibiotics (ATBs). METHODS AND MATERIALS: One hundred thirty-one patients had computerized tomography (CT)-planned transperineal 125I implantation of the prostate from 1988 through 1995. One hundred fourteen of the patients did not receive prophylactic ATBs, 19 of whom required postimplant Foley catheter drainage for 1 day or more for acute urinary retention. RESULTS: The incidence of postimplant febrile episodes within 2 weeks of surgery among the patients who had not received prophylactic ATBs was 2 of 114 (2%). One of the two patients who developed postimplantation febrile episodes was treated successfully with ATBs as an outpatient. The second patient, who had a history of chronic lymphocytic leukemia (CLL) and immune suppression, developed E. coli sepsis and required intravenous antibiotics. Of 17 patients who received prophylactic ATBs, none had a postoperative febrile episode. CONCLUSION: We continue to refrain from routinely prescribing prophylactic ATBs unless there is some compelling circumstance including rheumatic heart disease, prosthetic devices, immune compromise, or a previous history of prostatitis.

Aged↗
PubMed1996

Optimization of permanent 125I prostate implants using fast simulated annealing.

PURPOSE: Treatment planning of ultrasound-guided transperineal 125I permanent prostatic implants is a time-consuming task, due to the large number of seeds used and the very large number of possible source arrangements within the target volume. The goal of this work is to develop an algorithm based on fast simulated annealing allowing consistent and automatic dose distribution optimization in permanent 125I prostatic implants. METHODS AND MATERIALS: Fast simulated annealing is used to optimize the dose distribution by finding the best seed distribution through the minimization of a cost function. The cost function includes constraints on the dose at the periphery of the planned target volume and on the dose uniformity within this volume. Adjustment between peripheral dose and the dose uniformity can be achieved by varying the weight factor in the cost function. RESULTS: Fast simulated annealing algorithm finds very good seed distributions within 20,000 iterations. The computer time needed for the optimization of a typical permanent implant involving 60 seeds and 14 needles is approximately 15 min. An additional 5 min are necessary for isodose distribution computations and miscellaneous outputs. CONCLUSION: The use of fast simulated annealing allows for an efficient and rapid optimization of dose distribution. This algorithm is now routinely used at our institution in the clinical planning of 125I permanent transperineal prostate implants for early stage prostatic carcinoma.

Algorithms↗
PubMed1996

Six novel genes necessary for pre-mRNA splicing in Saccharomyces cerevisiae.

We have identified six new genes whose products are necessary for the splicing of nuclear pre-mRNA in the yeast Saccharomyces cerevisiae. A collection of 426 temperature-sensitive yeast strains was generated by EMS mutagenesis. These mutants were screened for pre-mRNA splicing defects by an RNA gel blot assay, using the intron- containing CRY1 and ACT1 genes as hybridization probes. We identified 20 temperature-sensitive mutants defective in pre-mRNA splicing. Twelve appear to be allelic to the previously identified prp2, prp3, prp6, prp16/prp23, prp18, prp19 or prp26 mutations that cause defects in spliceosome assembly or the first or second step of splicing. One is allelic to SNR14 encoding U4 snRNA. Six new complementation groups, prp29-prp34, were identified. Each of these mutants accumulates unspliced pre-mRNA at 37 degrees C and thus is blocked in spliceosome assembly or early steps of pre-mRNA splicing before the first cleavage and ligation reaction. The prp29 mutation is suppressed by multicopy PRP2 and displays incomplete patterns of complementation with prp2 alleles, suggesting that the PRP29 gene product may interact with that of PRP2. There are now at least 42 different gene products, including the five spliceosomal snRNAs and 37 different proteins that are necessary for pre-mRNA splicing in Saccharomyces cerevisiae. However, the number of yeast genes identifiable by this approach has not yet been exhausted.

Alleles↗
PubMed1996

Translocation (3;3) in a patient with thrombocytopenia and erythroid dysplasia.

We describe a case with a translocation between the two chromosomes 3 with breakpoints q21 and q26, associated with a unique constellation of hematologic abnormalities. Megakaryocytic dysplasia and peripheral thrombocytosis are the most common abnormalities associated with this chromosome abnormality. Our patient had acute myeloid leukemia (AML), thrombocytopenia, dyserythropoiesis, and an increased myeloid/erythroid ration but no mekakaryocytic dysplasia. Although multilineage involvement has been reported, erythrocyte dysplasia associated with thrombocytopenia and without megakaryocyte dysplasia appears to be extremely rare. Our case supports the speculation that #3 abnormalities with breakpoints q21 and q26 affect a pluripotent stem cell and suggests that megakaryocytic involvement may not be pathognomonic in hematologic abnormalities with t(3;3)(q21;26).

Chromosomes, Human, Pair 3↗
PubMed1996

Tumor control and morbidity following transperineal iodine 125 implantation for stage T1/T2 prostatic carcinoma.

PURPOSE: To quantify disease progression and morbidity following computer tomography (CT)-based transperineal iodine 125 prostate implantation. METHODS: Ninety-two patients with clinical stage T1 or T2, Gleason score 2 to 7/10, prostatic carcinoma had outpatient, CT-based transperineal 125I prostate implantation and were monitored for 1 to 7 years (median, 3). The prescribed minimum radiation dose was 140 to 160 Gy. Lymph node dissection and postimplantation prostatic biopsies were not routinely performed. RESULTS: In 46% of patients, radiation-related urinary symptoms were substantial enough at 1 month following implantation to require medication. Radiation-related urinary symptoms gradually resolved. Two years after implantation, 14% of patients had persistent urinary symptoms of Radiation Therapy Oncology Group (RTOG) > or = grade 2. Eight percent of patients underwent a transurethral resection of the prostate (TURP) within 2 years of implantation. Five patients developed radiation-induced rectal ulcerations. Of 56 patients who were sexually potent preimplantation, 86% retained potency at 3 years. Twenty-five patients had biochemical disease progression. The overall actuarial freedom from biochemical failure rate at 4 years following implantation was 63%. In Cox proportional hazards multivariate analysis, the strongest predictor of failure was prostate-specific antigen (PSA) level less than or greater than 10 ng/mL (P = .005), followed by Gleason score (2 to 4 v 5 to 7, P = .08) and stage (T1 v T2, P = .09). CONCLUSION: The 5-year biochemical freedom-from-progression rates following transperineal 125I implantation are comparable with those achieved with prostatectomy. The morbidity has decreased with increased physician experience.

Aged↗
PubMed1996

Treatment of essential thrombocythemia during pregnancy with interferon-alpha.

BACKGROUND: Only a few cases of essential thrombocythemia in pregnant women have been reported, and the management of this myeloproliferative disorder during pregnancy remains uncertain. We report a successful pregnancy in a patient who had essential thrombocythemia and who was treated with interferon-alpha, and we review the literature for the outcome of similar patients. CASE: A 32-year-old woman, gravida 4, para 3, aborta 0, presented at 18 weeks' gestation with two episodes of amaurosis fugax and an elevated platelet count of 2300 x 10(9)/L. The initiation of interferon-alpha led to a progressive fall of the platelet level, with no occurrence of thrombotic or hemorrhagic manifestations. Serial ultrasound examinations revealed normal fetal and placental development. The patient was delivered of a male infant at 37 weeks. Both child and placenta were normal on examination. CONCLUSION: Our case and the current available data suggest that interferon-alpha may be the best therapeutic option for pregnant patients with essential thrombocythemia in whom myelosuppression is required.

Adult↗
PubMed1996

[Prevention of second primary cancer with vitamin supplementation in patients treated for head and neck cancers].

Second primary cancers often occur in head and neck cancer patients successfully treated by radiation therapy. Experimental and epidemiological data suggest that these second primaries might be prevented by antioxidant vitamins, in particular beta-carotene and alpha-tocopherol. A randomized double-blind clinical trial is being conducted in Canada to determine whether vitamin supplementation with beta-carotene (30 mg/d) and alpha-tocopherol (400 IU/d) reduces the incidence of second primaries in head and neck cancer patients treated by radiation therapy.

Acetylcysteine↗
PubMed1996

[Incidence and risk factors of second primary cancers in patients treated for primary pharyngeal cancer].

About 13% of patients treated for a pharyngeal cancer suffer from a second primary cancer. Excessive consumptions of tobacco and/or alcohol are recognized as risk factors of second primary cancers in these patients. Epidemiologic studies suggest that antioxidant vitamins could have a protective effect on the occurrence of second primary cancers; however, this hypothesis should be confirmed by randomized clinical trials. A better knowledge of the risk factors of second primary cancers in patients with a pharyngeal cancer could help reducing the occurrence of second primary cancers and improving the follow-up of these patients.

Canada↗