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Biomedical subjects

S Das

Publications and source records attributed to S Das.

At least 343 records · Page 19Linked to original sources
PubMed1996

Laparoscopic complications in markedly obese urologic patients (a multi-institutional review)

OBJECTIVES: Significant obesity is considered to be a relative contraindication to laparoscopic surgery. This study reviews the complications encountered in massively obese patients undergoing urologic laparoscopic surgery. METHODS: Body mass index (BMI) was used as an objective index to indicate massive obesity. Eleven institutions compiled retrospective data on 125 patients having a BMI greater than 30. Procedures performed included 76 pelvic lymph node dissections, 14 nephrectomies, 7 bladder neck suspensions, and 28 miscellaneous procedures. RESULTS: For the group as a whole, the mean BMI was 35.1 (range 30.1 to 57.2). Mean operative time was 202 minutes (range 60 to 480). Conversion to open surgery occurred in 15 of the 125 patients (12%). Complication rates (minor and major) were 22% (27 occurrences in 125 patients) intraoperatively and 26% (33 occurrences in 125 patients) postoperatively. The major complications included 2 trocar injuries to abdominal wall vessels, 1 bladder injury, 3 peripheral nerve injuries, 1 dysrhythmia, 1 deep vein thrombosis, 1 wound seroma, 1 nephrocutaneous fistula, 1 incisional hernia, and 1 death. CONCLUSIONS: In this review, complication rates for urologic laparoscopic surgery on massively obese patients were higher than in the general population undergoing laparoscopic surgery (0.3% to 21%).

Adolescent↗
PubMed1996

A dose-response study of the effect of flutamide on benign prostatic hyperplasia: results of a multicenter study.

OBJECTIVES: The objective of this study was to evaluate efficacy, safety, and dose-response profiles of four dosing schemes of flutamide over 24 weeks. METHODS: Patients were randomized to receive one of the following five treatment regimens for a period of 24 weeks: placebo capsule, flutamide capsules 125 mg twice daily, 250 mg once daily, 250 mg twice daily, and 250 mg three times daily. Patients were then evaluated at baseline (0 weeks) and at 4, 6, 12, 18, and 24 weeks after the start of treatment, and 8 weeks after the end of treatment (32 weeks). Evaluation of efficacy was performed by noting changes in urine flow rate, residual urine volume, symptom score, prostate volume, and prostate-specific antigen level. A total of 372 patients were enrolled into the study at 32 centers (14 centers in the United States and 18 international centers). RESULTS: Baseline peak urinary flow rate and percent change from baseline in maximum flow rate showed a dose-related increase at 4 and 6 weeks; this increase was significant in the 250 mg three times daily group. At later time points, no significant differences between the flutamide and placebo groups were observed, largely because of the decreasing number of evaluable patients. At 4 and 6 weeks, 25% of patients in the 250 mg three times daily group had more than 3 cc/s increase in uroflow compared to about 10% of placebo patients (P < 0.05). All flutamide-treated groups had a significant decrease in prostate volume from baseline to the last treatment visit compared to placebo and this reduction was dose related (in comparison to placebo: P < 0.05 for 125 mg twice daily and P < 0.001 for all other treatment arms). Median decrease for the flutamide-treated groups ranged from 6% to 23% at 12 weeks and from 14% to 29% at 24 weeks. All treatment groups showed a subsequent increase in prostate volume after treatment was stopped. Furthermore, there was a significant reduction in residual urine volume at 24 weeks only in the 250 mg three times daily group. It increased following cessation of therapy. Urinary symptoms at 6, 12, 18, and 24 weeks did not show any significant difference between placebo and any flutamide dose group. The most common adverse events were nipple and breast tenderness (42% to 52%), diarrhea (29% to 34%), and gynecomastia (14% to 19%). Each of these adverse events had a significantly higher incidence in all flutamide dose groups compared with placebo, but none appeared to occur in a dose-related fashion. Sixteen percent of patients in the placebo group and 25% to 39% of patients in flutamide groups were discontinued due to diarrhea (12% to 17%) or nipple and breast tenderness (4% to 8%). A total of 1% to 3% of patients in various treatment arms discontinued due to deranged liver enzymes (1% for placebo); and 1% to 4% due to impotence (1% for placebo). CONCLUSIONS: Flutamide reduced the prostate volume in a dose-related fashion and resulted in an increase in peak flow rate at 4 weeks (3% for 250 mg three times daily, P value < 0.05), but the early positive effects did not maintain statistical significance due to an increasing number of dropouts due to adverse events. Effect on postvoid residual volume was observed only at the highest dose and at 24 weeks (median reduction, 23 mL, P < 0.05). Despite volume reduction and early improvement in peak flow rate, there were no significant differences in urinary symptoms among the placebo and flutamide groups. Higher incidences of diarrhea, breast tenderness, and gynecomastia, however, were the main limiting factors in this study and until these problems are overcome, the role of flutamide in the management of benign prostatic hyperplasia remains investigational.

Aged↗
PubMed1996

Women's satisfaction with traditional and reduced antenatal visit schedules.

OBJECTIVE: to ascertain: (i) which demographic, obstetric, maternity care, practical and attitudinal variables, and which variables relating to social support and life problems predict satisfaction with traditional antenatal visit schedules; and (ii) which of these variables predict satisfaction with reduced antenatal visit schedules. DESIGN: a secondary analysis of data from the Antenatal Care Project (a randomised controlled trial comparing two schedules of routine antenatal visits). SETTING: three hospitals and their community sites in south-east London. PARTICIPANTS: 1882 pregnant women, that is all those who took part in the Antenatal Care Project, on whom maternity record data were available, and who returned their antenatal questionnaire. INTERVENTION: participants were randomly allocated to follow either the traditional schedule of 13 routine antenatal visits, or a reduced schedule of seven visits for nulliparous women and six visits for multiparous women. MEASUREMENTS: a questionnaire developed specifically for the Antenatal Care Project. Also some data extracted from women's maternity records. FINDINGS: women satisfied with reduced schedules were more likely to live in rented accommodation, and to have a caregiver who both listened and encourage them to ask questions than women not satisfied with reduced schedules. Women satisfied with the reduced schedules were less likely to be depressed in pregnancy than those not satisfied with reduced schedules. Women satisfied with the traditional schedule were more likely to have their general practitioner involved in their antenatal care, and to receive social support from relatives than those not satisfied with the traditional schedule. Initial preferences and expectations were also associated with satisfaction. KEY CONCLUSIONS AND IMPLICATIONS FOR PRACTICE: (i) groups most likely to be satisfied with traditional or reduced antenatal visit schedules cannot be easily identified. It is therefore necessary to talk to women individually, and tailor care to their particular preferences; (ii) social support for depressed women needs to be safeguarded if reduced schedules are to be introduced; (iii) improving the psychosocial quality of antenatal care may be a good strategy for making reduced visit schedules more acceptable to pregnant women.

Adult↗
PubMed1996

A repeated element in the regulatory region of the MNK gene and its deletion in a patient with occipital horn syndrome.

Occipital horn syndrome (OHS), an X-linked connective tissue disorder, has recently been shown to result from mutations in the Menkes disease gene (MNK), which encodes a copper-transporting ATPase. By Southern analysis we detected a small deletion in a region 5' to the MNK gene in one patient with OHS. Genomic clones from an unaffected individual were isolated and sequenced, revealing three tandem 98 bp repeats situated upstream of the reported transcription start site, and analysis of the patient's DNA showed a deletion of one of the repeats. The deletion is likely to be responsible for the disease in this patient, as it was not observed in 110 unaffected individuals analyzed, and no other mutation in the patient was detected by RT-PCR and chemical cleavage mismatch analysis or by cDNA sequence analysis. The deletion is associated with a dramatic decrease in expression of a chloramphenicol acetyltransferase reporter gene, implicating the repeat sequences in regulation of MNK expression, although a quantitative analysis of MNK mRNA from a cell line derived from the patient shows no detectable reduction. Other experiments revealed no effect on the site of transcription initiation, termination or on splicing.

Adenosine Triphosphatases↗
PubMed1996

Role of thyroid hormone in the morphological differentiation and maturation of astrocytes: temporal correlation with synthesis and organization of actin.

Morphological changes and the molecular mechanisms associated with the maturation of astrocytes were studied under normal and thyroid hormone-deficient conditions using long-term (30 days) primary cultures derived from the neonatal rat brain. Immunocytochemical staining of cells with a monoclonal antibody specific to glial fibrillary acidic protein demonstrated for the first time that, similar to their maturation in vivo, astrocytes maintained in normal serum-containing medium can undergo complete maturation involving two distinct stages of morphological differentiation (from radial glia to flat polygonal cells with epithelioid morphology and then to mature process-bearing cells with stellate morphology). Deficiency of thyroid hormone delays the first step and totally blocks the second stage of differentiation in the maturation process. Comparative staining of normal and thyroid hormone-deficient astrocytes with filamentous actin-specific fluorescein isothiocyanate-phalloidin and quantitation of the various forms of intracellular actin using an improved DNase I assay demonstrated that maturation of astroglial cells is associated with characteristic alterations in the level of cytoskeletal and noncytoskeletal filamentous (F) actin. In particular, the maintenance of the epithelioid form of the hypothyroid astrocytes is associated with a progressive increase in the level of cytoskeletal F-actin and a concomitant decline in the level of non-cytoskeletal F-actin. Quantitation of actin mRNA by Northern blot analysis and studies on the rate of actin synthesis at various stages of differentiation showed that the initial transformation into the epithelioid form is associated with an increase in the rate of synthesis of actin and the expression of its mRNA, while the final transformation into the nature process-bearing form is correlated with a decline in these parameters. The results indicates that thyroid hormone plays an obligatory role in promoting the differentiation and maturation of astrocytes, and that during this process the hormone regulates the expression of actin and its intracellular organization in a way conducive to morphological differentiation.

Actins↗
PubMed1996

Sequences within a small yeast RNA required for inhibition of internal initiation of translation: interaction with La and other cellular proteins influences its inhibitory activity.

We recently reported purification, determination of the nucleotide sequence, and cloning of a 60-nucleotide RNA (I-RNA) from the yeast Saccharomyces cerevisiae which preferentially blocked cap-independent, internal ribosome entry site (IRES)-mediated translation programmed by the poliovirus (PV) 5' untranslated region (UTR). The I-RNA appeared to inhibit IRES-mediated translation by virtue of its ability to bind a 52-kDa polypeptide which interacts with the 5' UTR of viral RNA. We demonstrate here that the HeLa 52-kDa I-RNA-binding protein is immunologically identical to human La autoantigen. Moreover, I-RNA-mediated purified La protein. By using I-RNAs with defined deletions, we have identified sequences of I-RNA required for inhibition of internal initiation of translation. Two smaller fragments of I-RNA (16 and 25 nucleotides) inhibited PV UTR-mediated translation from both monocistronic and bicistronic RNAs. When transfected into HeLa cells, these derivatives of I-RNA inhibited translation of PV RNA. A comparison of protein binding by active and inactive I-RNA mutants demonstrates that in addition to the La protein, three other polypeptides with apparent molecular masses of 80, 70, and 37 kDa may influence the translation-inhibitory activity of I-RNA.

Autoantigens↗
PubMed1996

A novel species-specific tandem repeat DNA family from Sinapis arvensis: detection of telomere-like sequences.

DNA sequences representing a tandemly repeated DNA family of the Sinapis arvensis genome were cloned and characterized. The 700-bp tandem repeat family is represented by two clones, pSA35 and pSA52, which are 697 and 709 bp in length, respectively. Dot matrix analysis of the sequences indicates the presence of repeated elements within each monomeric unit. Sequence analysis of the repetitive region of clones pSA35 and pSA52 shows that there are several copies of a 7-bp repeat element organized in tandem. The consensus sequence of this repeat element is 5'-TTTAGGG-3'. These elements are highly mutated and the difference in length between the two clones is due to different copy numbers of these elements. The repetitive region of clone pSA35 has 26 copies of the element TTTAGGG, whereas clone pSA52 has 28 copies. The repetitive region in both clones is flanked on either side by inverted repeats that may be footprints of a transposition event. Sequence comparison indicates that the element TTTAGGG is identical to telomeric repeats present in Arabidopsis, maize, tomato, and other plants. However, Bal31 digestion kinetics indicates non-telomeric localization of the 700-bp tandem repeats. The clones represent a novel repeat family as (i) they contain telomere-like motifs as subrepeats within each unit; and (ii) they do not hybridize to related crucifers and are species-specific in nature.

Base Sequence↗
PubMed1996

A stimulatory role of cyclic adenosine 3',5'-monophosphate in follicle-stimulating hormone-activated mitogen-activated protein kinase signaling pathway in rat ovarian granulosa cells.

FSH promotes the differentiation of ovarian follicular granulosa cells via a cAMP-dependent mechanism. Based upon the presence of a prominent phospholipid/diolein/Ca2+-independent myelin basic protein kinase activity in soluble extracts of proliferating immature rat granulosa cells, we determine whether this activity was attributable to the mitogen-activated protein kinases (MAPKs), one of the ubiquitous families of myelin basic protein kinases, and whether FSH acutely regulated the MAPKs in rat granulosa cells. Granulosa cells were obtained from large preantral follicles in ovaries of immature rats treated with 17beta-estradiol to promote granulosa cell proliferation. Exposure of granulosa cells, cultured overnight in serum-free medium containing 10 nM 17beta- estradiol, to 50 ng/ml FSH for 10 min promoted a 2- to 5- fold increase in MAPK activity. The effects of FSH were mimicked by forskolin and inhibited by the inhibitor of cAMP- dependent protein kinase H89, but were not inhibited by the tyrosine kinase inhibitor Ag-18. FSH also promoted increased phosphorylation of the 90-kDa ribosomal S6 protein kinase and phosphorylation of exogenous S6 protein. These results suggest that the cAMP-directed pathway by which FSH initiates granulosa cell differentiation includes activation of MAPKs.

Animals↗
PubMed1996

Effect of noise stress on some cardiovascular parameters and audiovisual reaction time.

A study of the effect of noise stress on some of the physiological parameters was carried out on healthy male workers of thermal power station (exposed to sound level 90-113 dBA) and compared with age and sex matched healthy controls (exposed to sound level 48-66 dBA). The parameters recorded were heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP), galvanic skin resistance (GSR), auditory and visual reaction time (ART and VRT) and audiogram. Significant impairment in audiogram at 3000 Hz and 4000 Hz, increase in HR, SBP, DBP and decrease in GSR, ART and VRT were recorded in workers who were exposed to noise stress. Also a higher prevalence of hypertension was observed in them and that they were at a higher risk of developing hypertension than the control group. It was also observed that these modifications are related to duration of exposure to noise stress. It is presumed that all the above extra auditory effects are due to activation of autonomic nervous system and hypothalamo-hypophyseal adrenal axis, and the resultant release of catecholamines from adrenal medulla due to noise stress.

Acoustic Stimulation↗
PubMed1996

Colloid cyst xanthogranuloma of the third ventricle--a case report.

A colloid xanthogranuloma of the third ventricle is described. Presenting features were symptoms of raised intracranial tensions and two episodes of seizures. The pathogenesis, clinical and radiological features, differential diagnosis and treatment of this rare benign lesion are briefly discussed.

Adolescent↗
PubMed1995

An ospA frame shift, identified from DNA in Lyme arthritis synovial fluid, results in an outer surface protein A that does not bind protective antibodies.

Passive immunization with murine or human Abs to outer surface protein A (OspA) can protect mice against Borrelia burgdorferi, but OspA Abs elicited during natural infection in mice or humans are unable to clear the spirochete from the infected host. To examine Ab binding by OspA during the course of human infection, we amplified the operon encoding full-length ospA and ospB from synovial fluids of a patient with chronic Lyme arthritis, the first such recoveries from human material, at four separate time points over 4.5 mo, and expressed OspA in Escherichia coli. OspA mAbs that passively protected mice from infection did not bind one of the expressed OspAs, because of a deletion in ospA that resulted in a frame shift and premature stop codon near the carboxyl terminus. However, expressed OspA from a later synovial fluid sample did not contain this deletion. Thus, although altered forms of OspA, which potentially can influence host immune effectiveness, do occur in the human host, they cannot be the only factors responsible for microbial persistence.

Adolescent↗
PubMed1995

Conformal radiation therapy with fixed shaped coplanar or noncoplanar radiation beam bouquets: a possible alternative to radiosurgery.

PURPOSE: Three-dimensional (3D) geometric conformation of the therapeutic dose volume to the shape of a target tissue volume is the motivation for both conformal radiotherapy and radiosurgery. Although noncoplanar arcs have a clear physical and geometric advantage over fixed fields for small spherical targets, those advantages are reduced for large or irregularly shaped targets where static fields can be individually shaped. We have developed a system that allows efficient and flexible design and reliable delivery of customized "bouquets" of fixed nonopposed coplanar or noncoplanar shaped fields, resulting in highly uniform dose distributions. This report describes our initial experience using beam bouquets to treat intracranial lesions. METHODS AND MATERIALS: Patients with primary (11) or metastatic (4) intracranial lesions with a maximum diameter less than approximately 6 cm, most of whom candidates for single-fraction radiosurgery, were treated with beam bouquets of four to eight nonopposed coplanar or noncoplanar beams. Doses ranged from 16-20 Gy in four fractions for recurrent lesions (8) to 45 to 68 Gy in 25 to 34 fractions for primary lesions (7). The patients were immobilized with custom foam head supports and face masks attached to a fixed base plate. Planning computed tomography scans were acquired, from which the physician developed the custom beam bouquet using 3D treatment-planning tools. The bouquet was designed based primarily on geometric concerns. The bouquet was subsequently modified to add wedge filters chosen by vector analysis of dose gradients to achieve uniform dose over the volume of beam crossfire. At the time of treatment, the isocenter was placed using the instructions provided by the treatment-planning system and pretreatment orthogonal port films were compared to digitally reconstructed radiographs (DRR) to assure proper isocenter placement. For several situations, the 3D dose distributions resulting from alternative coplanar and noncoplanar plans were compared. RESULTS: Each patient was treated without incident. Daily pretreatment port films showed excellent reproducibility of isocenter placement in 87% of setups. With short follow-up (0-12 months), two patients with recurrent glioblastoma experienced clinical deterioration 2 to 4 weeks following treatment. One had increased edema on scans and responded to steroids. Six patients clinically improved following radiation therapy. Review of alternative treatment plans reveals that the relative utility of coplanar vs. noncoplanar beams is likely dependent on the location of the lesion. Noncoplanar beam bouquets are likely preferable to coplanar beams when the target is located in the central regions of the head. Coplanar beams are likely adequate, and possibly preferable, for peripherally located targets. CONCLUSION: The biological advantages of fractionation and the physical advantages of radiosurgery are exploited with this approach. The use of multiple nonopposed coplanar or noncoplanar conformal wedged fields provides a uniform dose to the target and acceptable dose gradient at the target edge. This technique may prove to be an alternative to arc-based radiosurgery in some settings and has the potential advantages that fractionation should improve the therapeutic ratio, and each beam can be individually shaped to conform to irregularly shaped targets. Additional studies are underway to improve this system and better define its utility.

Adult↗
PubMed1995

Amphibian parathyroids: morphological and functional aspects.

Amphibians living partially or totally in a terrestrial environment are the first tetrapods to possess parathyroid glands. Purely aquatic amphibians and amphibian larvae lack these endocrine glands. The parathyroids develop at the time of metamorphosis. The parathyroid glands in caecilians consist of a single cell type, that of urodeles may be composed of basal (supporting) cells and suprabasal (chief) cells, and that of anurans of small and large chief cells. Parathyroid glands of caecilians and anurans lack connective tissue, blood vessels, and nerves. The parathyroid cells become activated in response to decreased blood calcium concentration and undergo changes indicating increased parathyroid hormone secretion. Increased blood calcium concentration suppresses secretory activity. Usually, parathyroidectomy elicits hypocalcemia in most amphibians. Such operations have no effect in lower urodeles. Parathyroid hormone administration provokes hypercalcemia in most amphibians. The parathyroids of caecilians have not been studied in detail. The urodeles and anurans exhibit seasonal changes in the parathyroid glands. These changes may be initiated by environmental stimuli such as light, temperature, or alterations in blood calcium levels caused by natural hibernation.

Animals↗
PubMed1995

Effects of methylene blue and LY83583 on neuronal nitric oxide synthase and NADPH-diaphorase.

Methylene blue and 6-anilino-5,8-quinolinedione (LY83583) have often been used as 'selective' inhibitors of soluble guanylyl cyclase. We report that in in vitro assays, both these compounds were potent inhibitors of rat cerebellar nitric oxide synthase activity. Methylene blue had an apparent Ki of 2.7 microM, while for LY83583 the Ki was 15.8 microM. Furthermore, methylene blue, but not LY83583, inhibited the NADPH-diaphorase histochemical reaction associated with nitric oxide synthase. Our results indicate that many of the effects of these drugs which have been attributed to inhibition of guanylyl cyclase, may derive from their direct inhibition of nitric oxide synthase activity instead.

Aminoquinolines↗