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Biomedical subjects

S Roy

Publications and source records attributed to S Roy.

At least 613 records · Page 34Linked to original sources
PubMed1989

Murine MHC polymorphism and T cell specificities.

The major histocompatibility complex (MHC) genes are polymorphic in mouse and man. The products of these genes are receptors for peptides, which while bound, are displayed to T lymphocytes. When bound peptides from antigens are recognized by T lymphocytes, an immune response is initiated against the antigens. This study assessed the relation of the polymorphic MHC molecules to their peptide specificity. The results indicate that although an individual of the species has a limited ability to recognize antigens, the species as a whole has broad reactivity. This rationalizes the extreme polymorphism observed.

Animals↗
PubMed1989

Molecular characterization of a new immunoglobulin superfamily protein with potential roles in opioid binding and cell contact.

A purified opioid-binding protein has been characterized by cDNA cloning. The cDNA sequence predicts an extracellularly located glycoprotein of 345 amino acids. This protein does not possess a membrane-spanning domain but contains a C-terminal hydrophobic sequence characteristic of membrane attachment by a phosphatidylinositol linkage. It displays homology to the immunoglobulin protein superfamily, featuring three domains that resemble disulfide-bonded constant regions. More specifically, the protein is most homologous to a subfamily of proteins which includes the neural cell adhesion molecule (NCAM) and myelin-associated glycoprotein (MAG) and one subgroup of the tyrosine kinase growth factor receptors comprising the platelet-derived growth factor receptor (PDGF R), the colony-stimulating factor 1 receptor (CSF-1 R) and the c-kit protooncogene. These sequence homologies suggest that the protein could be involved in either cell recognition and adhesion, peptidergic ligand binding or both.

Amino Acid Sequence↗
PubMed1989

Ultrastructural study of micro-blood vessels in human brain tumors and peritumoral tissue.

Ultrastructural and tracer studies have demonstrated that vasogenic edema, a serious complication of brain tumor is the result of increased permeability of tumor vessels. However, not much information is available on the alterations in the vessels in the peritumoral areas. Therefore, we studied the ultrastructural changes in the tumor micro-blood vessels (MBVs) in 20 cases of glioma and compared these with the changes in the peritumoral MBVs in 10 of these cases. The tumor MBVs showed remarkable structural changes, viz, increase in pinocytotic vesicles, large vacuoles and microvilli in the endothelial cells, varying degrees of endothelial attenuation and fenestration, an occasional partially or completely opened-up junction and some pale and edematous endothelial cells, which can adequately explain their increased permeability. The peritumoral MBVs also showed evidence of increased permeability in the form of increased pinocytotic vesicles, large vacuoles and microvilli associated with pale and edematous cytoplasm of some endothelial cells. Thickened multilayered basement membrane, absence of ensheathment of capillary basement membrane by astrocytic cell processes and widened perivascular space were observed in both tumoral and peritumoral MBVs. An interesting observation was that in the peritumoral MBVs, the pinocytotic vesicles were most conspicuously seen on the abluminal side of the endothelial cells often fused with the abluminal plasma membrane. Although a static study like this cannot indicate any definite direction of movement of fluid, we feel that the occurrence of reverse pinocytosis is a distinct possibility in the peritumoral MBVs and that it may be an important means of resorption of edema fluid.

Basement Membrane↗
PubMed1989

Design and in vitro evaluation of dapsone-loaded micropellets of ethyl cellulose.

A controlled-release dosage form was manufactured by dispersing ethyl cellulose sol in acetone into a medium of mineral oil. Dapsone was used as the model drug. The powdered drug was dispersed in the ethyl cellulose sol, and the formulation variables affecting the production of the discrete and spherical micropellets and their size distribution were investigated. The percentage of SPAN 80 in the formulation affected the yield and physical properties of the micropellets. The in vitro drug release followed first-order diffusion-controlled dissolution. More than 85% of the drug was released over 5 hr for all formulation batches, with delayed release over the drug dissolution profile.

Capsules↗
PubMed1989

Sequential expression and cooperative interaction of c-Ha-ras and c-erbB genes in in vivo chemical carcinogenesis.

The level of expression of several cellular protooncogenes is examined at different stages of 7,12-dimethylbenzanthracene (DMBA)-induced tumor development in hamster buccal pouch epithelium (HBPE). Results presented demonstrate overexpression of c-Ha-ras gene at a very early stage of tumor development, and this elevated level of expression of the gene persists throughout the tumorigenesis process. The expression of the cellular protooncogene c-erbB, on the other hand, can be detected only after 8-10 weeks of DMBA treatment of the tissue and increases with the progression of the disease. The overexpression of c-erbB gene can be correlated with the stage of extensive proliferation and subsequent invasion of the HBPE cells into the underlying connective tissue. This sequential pattern of stage-specific expression of the two cellular protooncogenes can be observed in (i) treated tissues, (ii) stage-representative cultured cells, and (iii) NIH 3T3 transformants derived with DNA from HBPE cells. The low-level expression of c-myc and c-sis genes detected in control tissues remains unaffected, while c-fos gene activity cannot be detected at any stage of tumor development. The overexpression of c-Ha-ras gene alone in HBPE cells derived from tissues treated for 5 weeks (DM5) is not sufficient to induce tumors in athymic mice, whereas expression of c-Ha-ras and c-erbB genes at later stages of tumor development (DM10 and HCPC cells) induce histopathologically defined epithelial cell carcinoma in athymic mice within 2-3 weeks. The sequential overexpression of c-Ha-ras and c-erbB genes in a stage-specific manner and their cooperative interaction in the DMBA-induced in vivo oral carcinogenesis have been demonstrated.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1989

Comparative efficacy and safety of cefmetazole or cefoxitin in the prevention of postoperative infection following vaginal and abdominal hysterectomy.

We evaluated three 1-g doses of cefmetazole in comparison with the standard three 2-g doses of cefoxitin for prophylaxis in vaginal or abdominal hysterectomy to determine efficacy and safety. The antibiotics were administered intravenously 30-90 min before the incision and were followed with additional intravenous doses 8 and 16 h or 6 and 12 h later, respectively. The patients received povidone-iodine vaginal preparations before surgery; vaginal packs, when used, contained no antibiotic agents. Vaginal cultures were obtained before the vaginal preparation, at the time of discharge from hospital and when there was a suggestion of operative site infection. The activity of both antibiotics against these organisms was tested. Patient demographic characteristics and surgical procedures were similar in each treatment group. The difference between the primary failure rates with the two antibiotics (2 of 35 (5.7%) with cefmetazole and 2 of 16 (12.5%) with cefoxitin) did not reach statistical significance, and results were similar for the two routes of hysterectomy. Cefmetazole was more active than cefoxitin against the majority of the aerobic and anaerobic organisms recovered, although approximately 20-30% of the isolates showed resistance, or intermediate sensitivity, generally to both antibiotics.

Adult↗
PubMed1989

Prehepatic beta-cell secretion during the intravenous glucose tolerance test in humans: application of a combined model of insulin and C-peptide kinetics.

A previously introduced method by which prehepatic beta-cell secretion is calculated in vivo from plasma measurements of insulin and C-peptide was applied to data derived from iv glucose tolerance tests performed in normal women. Prehepatic secretory rates calculated using the combined model appeared biphasic in nature after glucose injection. Basal insulin secretion was 63.9 +/- 9.8 pmol/min. The duration of first phase was approximately 5 min, with secretion reaching a peak of 2033 +/- 342 pmol/min. The first phase was followed by a significant refractory period in which the secretory rate fell below basal values. The magnitude of second phase secretion was small relative to first phase secretion and appeared pulsatile in nature. Total integrated insulin secretion was 22.2 +/- 2.7 nmol, of which first phase accounted for 32%, and second phase accounted for the remaining 68%. Total incremental integrated secretion was 10.6 +/- 1.4 nmol, accounting for approximately half of the total insulin secretion. Proportions of first and second phase secretion changed to 66.5% and 33.5%, respectively, with incremental data. This study shows that the combined model of insulin and C-peptide is capable of estimating prehepatic insulin secretion from the iv glucose tolerance test and may provide a useful tool to measure secretion in vivo under various pathological conditions.

Adult↗
PubMed1989

Nuclear morphometric analysis of non-Hodgkin's lymphoma.

Nuclear morphometric data on resin-embedded sections have been utilized to classify 50 cases of non Hodgkin's lymphoma (NHL) and to compare with morphological classification. Nuclear morphometric parameters studied were maximum diameter (Dmax), area, perimeter, form factor (FF) and nuclear contour index (NCI). The first three are determinants of the size, and the latter two indicate the shape of nuclei. Based on Dmax, small (4.5-5.5 microns), intermediate (5.5-7.0 microns) and large (7.0-12.0 microns) cell lymphomas were identified, which correlate with the low, intermediate and high grade lymphomas respectively of the Working Formulation. Determination of form factor further helped to subclassify these cases into lymphomas of B cell other than of follicular centre cell origin (FF = 0.7-1.0), follicular centre cell lymphomas (FF = 0.55-0.75) and T-cell lymphomas (FF less than 0.55). Pleomorphism factor is an objective assessment of the degree of morphological pleomorphism and is generally proportional to the grade of malignancy.

Cell Nucleus↗
PubMed1989

Acute effect of anhydrous glycerol on peripheral nerve: an experimental study.

Percutaneous retrogasserian glycerol rhizotomy has shown encouraging results in the treatment of trigeminal neuralgia. An experimental study was undertaken using a rat sciatic nerve model to elucidate the mechanism of action of anhydrous glycerol and to study the acute changes which develop within one week. Extraneural glycerol was applied in 20 adult Wistar rats. Groups of five animals were sacrificed at days 1, 3, 5 and 7 respectively. The sciatic nerve of the opposite limb in the same animals was used as a control. The nerve were examined with light and electron microscopy including a morphometric study to assess the type of fibres affected. The specific pattern of involvement of larger and medium sized myelinated fibres with relative preservation of unmyelinated fibres was noted.

Animals↗
PubMed1989

Primitive neuroectodermal tumours of the central nervous system--an electron microscopic & immunohistochemical study.

A series of 75 poorly differentiated neoplasms of the central nervous system viz., medullo-blastoma, cerebral neuroblastoma, pineoblastoma and ependymoblastoma were studied by light microscopy (LM), electron microscopy (EM) and immunohistochemistry (IH). Although the predominant cells constituting these tumours appeared to be undifferentiated cells by LM and EM, many others showed evidence of differentiation into glial, neuronal or ependymal cell lines by EM and IH. It is therefore, concluded that all these neoplasms are best considered as primitive neuroectodermal tumours and these may be classified as such in neuro-oncology. They may be subclassified further on the basis of differentiation into one or more cell lines.

Brain Neoplasms↗
PubMed1989

Medullomyoblastoma. A case report.

A case of medullomyoblastoma was studied by light and electron microscopy and by immunohistochemistry. It showed glial and neuronal differentiation in the medulloblastoma areas and rhabdomyoblastic differentiation in the intervening areas.

Cerebellar Neoplasms↗
PubMed1989

[Spiramycin].

Chemotherapeutic agents appear to offer a great potential in the treatment of periodontal disease in conjunction with root planning and/or surgical approach. One of these chemotherapeutic agents is spiramycin. The aim of this paper is to review some data about the spiramycin in vitro, in vivo, the effects of spiramycin on plaque control and some interesting hypothesis on action of spiramycin.

Dental Plaque↗
PubMed1989

Pelvic abscesses in postmenopausal women.

Seventeen postmenopausal women with pelvic abscesses were cared for at the Los Angeles County-University of Southern California Women's Hospital during the past eight years. Nine had experienced either postmenopausal bleeding or uterine instrumentation, or both, within the prior six months. Findings from physical examination and various laboratory and roentgenologic studies did not significantly help in improving the accuracy of preoperative diagnosis. In four, the abscess was associated with intra-abdominal pathologic conditions, and six had poorly controlled adult onset diabetes mellitus. Transfusion was required in eight patients. Two patients had a prolonged hospital stay because of pulmonary and septic complications. One patient had carcinoma of the ovary while another had carcinoma of the cervix uteri that was undiagnosed preoperatively. Our conclusion is that about one-half of postmenopausal patients with pelvic and tubo-ovarian abscesses have postmenopausal bleeding. The remainder may have associated intra-abdominal infective pathologic findings or a malignant condition of the genital tract. Expeditious surgical treatment should be undertaken.

Abscess↗
PubMed1988

A monoclonal antibody that inhibits opioid binding to rat brain membranes.

To understand the structure-function relationship and to probe the molecular characteristics of the purified opioid receptor, monoclonal antibodies (mab) were raised against a purified opioid receptor protein. After intensive screening of almost 1500 hybridoma cell lines, only 7 clones were shown to have very high immunoreactivity against the purified receptor. Moreover, out of these 7 clones, only 2, 3B4F11 and 3A27G, were found to inhibit the ligand binding property of the mu-opioid receptor. The mab 3B4F11 was found to inhibit 3H-diprenorphine binding to the purified receptor in a dose dependent manner with a maximal inhibition of 100% achieved with 20 micrograms of the antibody. Likewise, Fab fragments prepared from the mabs 3B4F11 inhibited 3H-diprenorphine binding to P2 membranes in a dose-dependent manner. In addition, it was found that the binding of 3H-DAGO, 3H-DPDPE and 3H-EKC was inhibited with approximately equal potency, suggesting that the Fabs prepared from the mab 3B4F11 interact with all 3 receptor types.

3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cycloh↗