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Biomedical subjects

A Das

Publications and source records attributed to A Das.

At least 145 records · Page 8Linked to original sources
PubMed1999

Multicomponent penile prosthesis implantation under regional anesthesia.

Fourteen consecutive patients underwent placement of a multicomponent penile prosthesis under regional anesthesia using a pudendal nerve block. Results demonstrated the need for minimal administration of intraoperative narcotics, no major fluctuations in the blood pressure or pulse rate during intraoperative monitoring, and only 1 of 14 patients was converted to general anesthesia. Postoperatively, our results show that there was no urinary retention or cardiac side effects, adequate postoperative analgesia was obtained, and 13 of the 14 patients were discharged within 24 hours. This method was safe, effective, easily performed, and does not carry the associated morbidity of general or spinal anesthesia.

Anesthetics, Local↗
PubMed1999

The neurological manifestations of Nipah virus encephalitis, a novel paramyxovirus.

A novel Hendra-like paramyxovirus named Nipah virus (NiV) was the cause of an outbreak among workers from one abattoir who had contact with pigs. Two patients had only respiratory symptoms, while 9 patients had encephalitis, 7 of whom are described in this report. Neurological involvement was diverse and multifocal, including aseptic meningitis, diffuse encephalitis, and focal brainstem involvement. Cerebellar signs were relatively common. Magnetic resonance imaging scans of the brain showed scattered lesions. IgM antibodies against Hendra virus (HeV) were present in the serum of all patients. Two patients recovered completely. Five had residual deficits 8 weeks later.

Adult↗
PubMed1999

Prevention of visual loss in older adults.

The major causes of visual loss in older adults are cataracts, glaucoma, age-related macular degeneration, and diabetic retinopathy. Intensive research is ongoing for the prevention of these diseases. The present article updates different research studies and clinical trials aimed at prevention of visual loss in older adults.

Aged↗
PubMed1998

The D arm of tRNATyr is necessary and sufficient for import into Leishmania mitochondria in vitro.

Transfer RNAs are selectively imported from the cytoplasm into mitochondria of kinetoplastid protozoa such as Leishmania . The specific structural features of tRNA which determine selectivity are largely unknown. Using an in organello system from Leishmania , the import signals on tRNATyrand on a synthetic transcript which binds to the same receptor, were studied by deletion and reconstruction analyses. In both cases, short oligoribonucleotides (minihelices) containing the sequence UGGYAGAG were imported with high efficiency in the presence of ATP. This motif is present in the D arm of tRNATyr, as well as in the majority of imported Leishmania tRNAs. Deletion of the D arm, or a point mutation in the conserved motif, reduces importability. The import signal coincides with the binding site for the mitochondrial receptor TAB. tRNAGln, which is not imported, forms non-productive, TAB-independent complexes with the mitochondrial surface. However, the observation that the imported:bound ratio of the D arm minihelix is higher than that of the entire molecule suggests that the post-binding translocation step is constrained in terms of size or structural flexibility. Kinetic studies of minihelix import indicate stepwise insertion of the molecule into import channels.

Animals↗
PubMed1998

Plasma ferritin, premature rupture of membranes, and pregnancy outcome.

OBJECTIVE: The objective of this study was to determine whether plasma ferritin levels predict maternal or neonatal outcomes in women with preterm rupture of membranes at <32 weeks' gestation. METHODS: Plasma from 223 women with premature rupture of membranes at <32 weeks' gestation who had participated in a randomized antibiotic trial were analyzed for ferritin at random assignment and at delivery, and the results were compared with the development of clinical chorioamnionitis, latency until delivery, neonatal sepsis, and a composite adverse neonatal outcome variable. RESULTS: The mean plasma ferritin level rose from 19.2 +/- 29.1 microgram/L on admission to 38.3 +/- 54.3 microgram/L at delivery, with a mean latency of 9.3 +/- 14.6 days. Plasma ferritin levels were significantly higher at both times in mothers whose infants acquired sepsis than in those whose infants did not, especially at delivery (68.5 +/- 96.3 microgram/L vs 32.5 +/- 40.5 microgram/L, P =.01), and neonatal sepsis was 2 to 3 times more common among women with plasma ferritin levels above the median than among those with levels below the median. CONCLUSIONS: Among women with premature rupture of membranes at <32 weeks' gestation, plasma ferritin levels were significantly associated with neonatal sepsis. These data suggest that higher plasma ferritin levels may serve as a marker of infection among women with premature rupture of membranes; however, the clinical utility of plasma ferritin levels in predicting neonatal outcome appears limited.

Adult↗
PubMed1998

The preterm prediction study: risk factors for indicated preterm births. Maternal-Fetal Medicine Units Network of the National Institute of Child Health and Human Development.

OBJECTIVE: Preterm births occur for many different reasons. Most efforts to identify risk factors for preterm births either ignore cause and consider preterm births as a single entity or examine risk factors for spontaneous preterm births. We performed this study to examine risk factors for indicated preterm births, which constitute more than one quarter of all preterm births. STUDY DESIGN: The study included 2929 women evaluated at 24 weeks' gestation at 10 centers. Information was gathered about demographic factors, socioeconomic status, home and work environments, drug and alcohol use, and medical history. In addition vaginal samples were evaluated for fetal fibronectin and bacterial vaginosis and cervical length was measured by transvaginal ultrasonography. Associations with indicated preterm birth were evaluated by univariate tests and by multivariable analysis with logistic regression. RESULTS: Of the women studied at 24 weeks' gestation 15.3% were delivered of their infants at <37 weeks' gestation. Of these deliveries, 27.7% were indicated preterm births. Risk factors in the final multivariable model were, in order of decreasing odds ratios, mullerian duct abnormality (odds ratio 7.02), proteinuria at <24 weeks' gestation (odds ratio 5.85), history of chronic hypertension (odds ratio 4.06), history of previous indicated preterm birth (odds ratio 2.79), history of lung disease (odds ratio 2.52), previous spontaneous preterm birth (odds ratio 2.45), age >30 years (odds ratio 2.42), black ethnicity (odds ratio 1.56), and working during pregnancy (odds ratio 1.49). Alcohol use in pregnancy was actually associated with a lower risk of indicated preterm birth (odds ratio 0.35). CONCLUSION: The risk factors found in this analysis tend to be different from those associated with spontaneous preterm birth.

Adolescent↗
PubMed1998

Study of ethmoid sinus involvement in multibacillary leprosy.

The nasal mucosal involvement in lepromatous leprosy is well recognized. Currently interest has centred around the involvement of paranasal sinuses in leprosy. They act as a reservoir and constant source of reinfection to the nasal mucosa. In the present prospective study 25 untreated patients with multi-bacillary leprosy were included. Clinical examination, computed tomography (CT) scan of paranasal sinuses, ethmoid sinus endoscopy and biopsy were carried out in all patients, to investigate the involvement of the paranasal sinuses in leprosy. Ethmoid sinus involvement was noted in 20 patients on CT scan. Bilateral involvement was more common (65 per cent). Anterior ethmoids were more commonly affected (65 per cent). On ethmoid sinus endoscopy abnormal mucosa was noted in 17 patients (68 per cent). Ethmoid sinus biopsy was confirmative in 16 patients (64 per cent). Statistically significant correlation was found between CT findings, sinus endoscopy and sinus biopsy findings.

Adolescent↗
PubMed1998

Surface chemical studies of Thiobacillus ferrooxidans with reference to copper tolerance.

A strain of Thiobacillus ferrooxidans was adapted to grow at higher concentrations of copper by single step culturing in the presence of 20 g/L (0.314 mol/L) cupric ions added to 9K medium. Exposure to copper results in change in the surface chemistry of the microorganism. The isoelectric point of the adapted strain (pI = 4.7) was observed to be at a higher pH than that of the wild unadapted strain (pI = 2.0). Compared to the wild strain, the copper adapted strain was found to be more hydrophobic and showed enhanced attachment efficiency to the pyrite mineral. The copper adsorption ability of the adapted strain was also found to be higher than that of the wild strain. Fourier transform infrared spectroscopy of adapted cells suggested that a proteinaceous new cell surface component is synthesized by the adapted strain. Treatment of adapted cells with proteinase-K, resulted in complete loss of tolerance to copper, reduction in copper adsorption and hydrophobicity of the adopted cells. These observations strongly suggest a role played by cell surface modifications of Thiobacillus ferrooxidans in imparting the copper tolerance to the cells and bioleaching of sulphide minerals.

Acidithiobacillus thiooxidans↗
PubMed1998

Construction of transposon Tn3phoA: its application in defining the membrane topology of the Agrobacterium tumefaciens DNA transfer proteins.

Protein fusion with the Escherichia coli alkaline phosphatase is used extensively for the analysis of the topology of membrane proteins. To study the topology of the Agrobacterium T-DNA transfer proteins, we constructed a transposon, Tn3phoA. The transposon mobilizes into plasmids at a high frequency, is stable after transposition, can produce phoA translational fusions and can be used for the analysis of protein topology directly in the bacterium of interest. For studies on the DNA transfer proteins, an Agrobacterium strain deficient in phoA under our experimental conditions was constructed by chemical mutagenesis. A plasmid containing virB and virD4 was used as a target for mutagenesis. Twenty-eight unique phoA-positive clones that mapped to eight virB genes were isolated. Multiple insertions throughout VirB1, VirB5, VirB7, VirB9 and VirB10 indicated that these proteins primarily face the periplasm. Insertions in VirB2, VirB6 and VirB8 allowed the identification of their periplasmic domains. No insertions were found in VirB3, VirB4 and VirB11. These proteins either lack or have a short periplasmic domain. No insertions mapped to VirD4 either. To study VirD4 topology, targeted phoA fusions and random lacZ fusions were constructed. Analysis of the fusion proteins indicated that VirD4 contains a single periplasmic domain near the N-terminus, and most of the protein lies in the cytoplasm. A hypothetical model for the T-DNA transport pore is presented.

Agrobacterium tumefaciens↗
PubMed1998

Effect of intravesical capsaicin and vehicle on bladder integrity control and spinal cord injured rats.

PURPOSE: To determine the acute effect of intravesical capsaicin on bladder mucosal integrity in normal and spinal cord injured (SCI) rats. MATERIALS AND METHODS: Intravesical reagents were instilled in 5 groups of age and weight matched female rats: 1) control + normal saline solution (NSS), 2) control + ethanol (EtOH), 3) control + capsaicin/EtOH, 4) SCI + NSS, 5) SCI + capsaicin/EtOH. Intravesical instillations were performed 4 weeks after a standard T10 SCI. Intravesical capsaicin (1 mM.) was dissolved in 30% EtOH/NSS. The animals (n = 3 each group) were sacrificed at 30 minutes, 24 hours, 72 hours, and 7 days after intravesical instillation. Whole bladders were harvested, fixed in 10% buffered formalin, and paraffin embedded. Tissue blocks were blind coded and sectioned (5 microns thickness) for histopathological analysis. All sections were initially stained with hematoxylin and eosin (H & E). Specific staining for mucin carbohydrate moieties included periodic acid-Schiff (PAS) and alcian blue. Also, immunohistochemical staining for GP51 (a urinary glycoprotein) was performed. RESULTS: Control and SCI rats exhibited similar bladder mucosal histology by H & E and mucin specific stains. Instillation of saline demonstrated no effect on bladder histology, whereas instillation of intravesical capsaicin induced a profound acute effect of thinning of the epithelium, submucosal edema, and diminished presence of GP51. EtOH produced similar pathological findings, but to a lesser degree than capsaicin. Intravesical capsaicin demonstrated a similar effect in both control and SCI animals. The peak effect was seen after 30 minutes and continued for 24 hours. Partial recovery was noted after 72 hours and complete recovery was evident by 1 week. CONCLUSIONS: The control and SCI rats demonstrated a histologically similar mucosa and glycosaminoglycan layer. The effect of saline instillation on the mucosa was negligible. Intravesical capsaicin dissolved in 30% ethanol/NSS had a profound effect on the bladder urothelium submucosa that was more pronounced than that seen with the ethanol vehicle alone in normal animals.

Administration, Intravesical↗
PubMed1998

A cost analysis of long term antibiotic prophylaxis for spontaneous bacterial peritonitis in cirrhosis.

OBJECTIVE: The aim of this study was to perform a cost analysis of different strategies of long term antibiotic prophylaxis for spontaneous bacterial peritonitis (SBP) in patients with cirrhosis and ascites. The study involved a cost analysis using a decision analysis model and patients with cirrhosis and ascites who are at risk for developing SBP. METHODS: Two different strategies of antibiotic prophylaxis were compared with a "no prophylaxis" strategy in patients with cirrhosis and ascites using a decision analysis model. In strategy I, antibiotic prophylaxis was administered in all patients with cirrhosis and ascites and in strategy II, patients were stratified into a low risk and a high risk group on the basis of serum bilirubin and ascitic fluid protein levels; only patients in the high risk group received antibiotic prophylaxis. The cost per patient treated for 1 yr was the outcome measure compared in the different strategies. Clinical input probabilities and ranges used were obtained by searching the MEDLINE database for English language articles. Cost estimates were obtained from a university hospital setting. Cost analysis was done with a societal perspective, and only direct costs were taken into account. Sensitivity analyses were performed to evaluate the effect of variations in the key clinical probabilities and cost estimates ranging from a best case to a worst case scenario on the outcome measure. RESULTS: The estimated cost per patient treated in strategy I, strategy II, and strategy III (the strategy of "no prophylaxis") were $1311, $1123, and $3509, respectively. Over a broad range of clinical and cost variables, the strategy of risk stratification and restriction of antibiotic prophylaxis to the subgroup of patients with cirrhosis and ascites who were at high risk for SBP (as identified by serum bilirubin >2.5 mg/dl and ascitic fluid protein <1 g/dl) was the most favored strategy. However, when the cost of prophylaxis was low or the probability of a primary episode of SBP was at the lower end of the range reported in the literature, administering antibiotic prophylaxis to all patients with cirrhosis and ascites was the least costly strategy. CONCLUSION: This cost analysis indicates that antibiotic prophylaxis particularly when restricted to a subgroup of patients who, by simple laboratory parameters, are identified to be at high risk for SBP, is very cost-effective in the prevention of SBP in patients with cirrhosis and ascites.

Antibiotic Prophylaxis↗
PubMed1998

Diospyrin, a bisnaphthoquinone: a novel inhibitor of type I DNA topoisomerase of Leishmania donovani.

Diospyrin is a plant product that has significant inhibitory effect on the growth of Leishmania donovani promastigotes. This compound inhibits the catalytic activity of DNA topoisomerase I of the parasite. Like camptothecin, it induces topoisomerase I mediated DNA cleavage in vitro. Treatment of DNA with diospyrin before addition of topoisomerase I has no effect. Preincubation of topoisomerase I with diospyrin before the addition of DNA in the relaxation reaction increases this inhibition. Our results suggest that this bis-naphthoquinone compound exerts its inhibitory effect by binding with the enzyme and stabilizing the topoisomerase I-DNA "cleavable complex." Diospyrin is a specific inhibitor of the parasitic topoisomerase I. It does not inhibit type II topoisomerase of L. donovani and requires much higher concentrations to inhibit type I topoisomerase of calf thymus. The potent inhibitory effect of diospyrin on type I DNA topoisomerase from L. donovani can be exploited for rational drug design in human leishmaniasis.

Animals↗
PubMed1998

Distinct domains of a nucleolar protein mediate protein kinase binding, interaction with nucleic acids and nucleolar localization.

Nopp44/46 is a phosphoprotein of the protozoan parasite Trypanosoma brucei that is localized to the nucleolus. Based on the primary sequence, Nopp44/46 appears to be a protein composed of distinct domains. This communication describes the relationship of these domains to the known functional interactions of the molecule and suggests that the amino-terminal region defines a novel homology region that functions in nucleolar targeting. We have previously shown that Nopp44/46 is capable of interacting with nucleic acids and associating with a protein kinase. Using in vitro transcription and translation, we now demonstrate that the nucleic acid binding function maps to the carboxy-terminal domain of the molecule, a region rich in arginine-glycine-glycine motifs. Our experiments reveal that a central region containing a high proportion of acidic residues is required for association with the protein kinase. Analysis of transfectants expressing epitope-tagged Nopp44/46 deletion constructs showed that the amino-terminal 96 amino acids allowed nuclear and nucleolar accumulation of the protein. This region of the molecule shows homology to several recently described nucleolar proteins. Deletion of a 27-amino-acid region within this domain abrogated nucleolar, but not nuclear, localization. These studies show that Nopp44/46 is composed of distinct modules, each of which plays a different role in molecular interactions. We suggest that this protein could facilitate interactions between sets of nucleolar molecules.

Amino Acid Sequence↗
PubMed1998

The preterm prediction study: the value of new vs standard risk factors in predicting early and all spontaneous preterm births. NICHD MFMU Network.

OBJECTIVES: This study was undertaken to determine the relationship between fetal fibronectin, short cervix, bacterial vaginosis, other traditional risk factors, and spontaneous preterm birth. METHODS: From 1992 through 1994, 2929 women were screened at the gestational age 22 to 24 weeks. RESULTS: The odds ratios for spontaneous preterm birth were highest for fetal fibronectin, followed by a short cervix and history of preterm birth. These factors, as well as bacterial vaginosis, were more strongly associated with early than with late spontaneous preterm birth. Bacterial vaginosis was more common--and a stronger predictor of spontaneous preterm birth--in Black women, while body mass index less than 19.8 was a stronger predictor in non-Black women. This analysis suggests a pathway leading from Black race through bacterial vaginosis and fetal fibronectin to spontaneous preterm birth. Prior preterm birth is associated with spontaneous preterm birth through a short cervix. CONCLUSIONS: Fetal fibronectin and a short cervix are stronger predictors of spontaneous preterm birth than traditional risk factors. Bacterial vaginosis was found more often in Black than in non-Black women and accounted for 40% of the attributable risk for spontaneous preterm birth at less than 32 weeks.

Cervix Uteri↗