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Biomedical subjects

A Das

Publications and source records attributed to A Das.

At least 91 records · Page 5Linked to original sources
PubMed2001

Neuropathological complications of infective endocarditis : study of autopsy material.

78 autopsy proven cases of infective endocarditis (IE) seen during 1983 to 1995 were retrospectively reviewed. The brain was available for examination in 44 cases. In the remaining cases, brain was not examined because examination of it was not requested due to lack of neurological findings. Brain lesions were observed in 35 out of 44 cases of IE. Assuming remaining 34 cases to be without brain lesions, the brain involvement in IE would be 44.87% (35 out of 78 cases). Mean age of all cases of IE and those with brain lesions was similar i.e. 26.5+/-16.6 years and 26.6+/-13.06 years respectively. Largest number of cases with neuropathological lesions were associated with normal valve IE (48.57%). Mitral valve was most commonly involved in cases with CNS complications (57.14%) (p<0.05). The various types of brain lesions were infarction (68.57%), haemorrhage (57.14%), cerebral micro-abscess (31.42%) and focal meningitis (14.28%). More than one type of lesion was observed in 19 cases, indicating complicated nature of brain lesions in fatal cases of IE. Left sided middle cerebral artery (MCA) territory was the commonest site of infarction and haemorrhage. Staphylococcus aureus appeared to be the most common organism in fatal cases of IE. Normal valve IE with or without CNS complications constitutes a significant group in India and is different from the west as far as the predisposing conditions are concerned.

Adolescent↗
PubMed2001

Visual performance of rigid gas permeable contact lenses in patients with corneal opacity.

PURPOSE: To evaluate the visual performance of rigid gas permeable (RGP) contact lenses in patients with nebular and nebulo-macular corneal opacity and correlate the improvement in visual acuity with other visual parameters. METHODS: In a prospective study, visual performance of RGP contact lenses was evaluated in eyes with corneal opacity involving the pupillary area. The baseline visual acuity and other visual parameters with glasses were compared with those recorded with RGP contact lenses. The visual functions evaluated were visual acuity, contrast sensitivity, glare acuity, and mesopic vision. Binocular status with RGP contact lenses was assessed. All patients were followed up for 3 months. RESULTS: Twenty-eight eyes (26 patients) with nebular or nebulo-macular corneal opacity were included in this study. All eyes (100%) achieved significantly better visual performance with RGP contact lenses than with glasses (P< 0.0020). Visual acuity of 6/9 or better was achieved in 50% of patients with RGP contact lenses compared to none with glasses. RGP contact lenses improved the visual acuity by 0.27 decimals over the baseline value with glasses, butthe improvement for mesopic vision and glare acuity was significantly lower at 0.15 and 0.06 decimals respectively. Similarly, contrast sensitivity did not improve to the same extent as visual acuity. Stereopsis was present only in patients with best corrected visual acuity of 6/9 or better with RGP lenses. CONCLUSION: RGP contact lenses improved the visual acuity and other visual performance in patients with reduced vision due to nebular or nebulo-macular corneal opacity. However, contrast sensitivity, glare acuity, and mesopic vision did not improve to the same extent as visual acuity.

Adolescent↗
PubMed2001

Safety of three toothbrushes.

PURPOSE: To assess the oral soft tissue safety and tolerability of two electric toothbrushes, the Crest Spin Brush and Colgate ActiBrush, and one manual toothbrush, the Oral B 40. MATERIALS AND METHODS: A total of 104 subjects were enrolled in this single center, randomized, examiner-blind parallel study over a 4-wk test period. Subjects were randomized to treatment and were instructed to brush in their normal manner, twice per day for 60 s. A detailed oral soft tissue examination and interview were conducted by a trained clinician at baseline, 3 days and 4 wks to assess clinical signs and symptoms associated with use of the toothbrushes. RESULTS: Over the 4-wk period, a total of 19 subjects (18% of the study population) were observed for signs/symptoms. The adverse events were distributed across test groups with 12 subjects in the Oral B 40 group, 4 subjects in the Crest Spin Brush group, and 3 subjects in the Colgate ActiBrush group experiencing at least one adverse event. All adverse events were mild in severity indicating the general safety of all three toothbrushes. The most frequently encountered event was localized gingivitis. The Oral B 40 test group was observed with more adverse events when compared to the Crest Spin Brush and Colgate ActiBrush at 4 wks but not at 3 days. The proportion of subjects experiencing an adverse event in the Crest Spin Brush test group was similar to that of Colgate ActiBrush group. All three toothbrushes were generally well tolerated by subjects enrolled in the study with the Crest Spin Brush and Colgate ActiBrush being the best tolerated. CLINICAL SIGNIFICANCE: The results of this study indicated that abnormal oral soft tissue findings were distributed among the treatment groups, indicating that daily use of an electric toothbrush is at least as safe as a manual toothbrush.

Adult↗
PubMed2001

Screening for high- and moderate-risk drinking during pregnancy: a comparison of several TWEAK-based screeners.

PURPOSE: This study investigated the use of the TWEAK and nine alternative screeners for predicting high-risk and moderate-risk drinking during pregnancy. METHOD: The analysis was based on self-reports from 404 lifetime drinkers who presented for an initial visit at nine prenatal clinics in Washington, DC. Data were collected anonymously by having women directly enter their responses onto an audio, computer-assisted interview that was programmed onto a laptop computer. Pregnancy risk drinking status was based on both average daily volume of intake and frequency of drinking 3+ drinks in a day. Each of the alternative screeners was constructed by adding one additional risk indicator to the TWEAK, and three different scoring options were explored. RESULTS: Using thresholds of 2 points for high-risk drinking and 1 point for moderate-risk drinking, the TWEAK demonstrated a sensitivity and specificity of 70.6% and 73.2% for high-risk drinking and a sensitivity and specificity of 65.6% and 63.7% for any (high- or moderate-) risk drinking during pregnancy. None of the alternative screeners resulted in significant improvement, but the addition of current smoking status showed enough promise to warrant further testing in larger samples. CONCLUSIONS: Despite some loss in sensitivity and specificity, the TWEAK, in its original or a modified form, can be extended to measures of high-risk drinking that incorporate infrequent heavy intake and can be used to test for moderate- as well as high-risk drinking. Because identification of moderate-risk drinkers substantially increases the pool of women targeted for intervention, cost implications must be considered in designing appropriate interventions.

Adult↗
PubMed2001

Holmium laser resection of the prostate (HoLRP): 2-year follow-up data.

PURPOSE: The aim of this study was to evaluate the 2-year clinical outcome of patients who underwent holmium laser resection of the prostate (HoLRP) for management of benign prostatic hyperplasia (BPH). MATERIALS AND METHODS: All patients who underwent HoLRP before October 1995 were contacted by mail. Each patient completed an American Urological Association (AUA) symptom score index, a questionnaire, and a urinary flow rate. The questionnaire was used to evaluate the frequency of complications, incontinence, recatheterization, and patient satisfaction. RESULTS: Two hundred twelve patients were contacted and 168 responded. Of these, 100 patients successfully completed all three investigations and had all preoperative information available. Mean length of follow-up was 27.5 months (range 24 to 34 months). Mean peak urinary flow was 21.6 mL/s (range 6 to 34 mL/s), mean voided volume was 348 mL (range 146 to 1,387 mL), and mean AUA symptom score index was 6.8 (range 0 to 27). Eighty-eight percent of patients stated they would have HoLRP again for management of their BPH. The perioperative recatheterization rate was 9%. Reoperation rate with a minimum of 2 years of follow-up was 5%; three patients required a bladder neck incision and two patients required a revision HoLRP. Urethral strictures occurred in 4% of patients, and 1% of patients had persistent incontinence requiring pads. CONCLUSIONS: Medium-term clinical results of HoLRP confirm that patient satisfaction is excellent, with complication rates similar to those historically reported for transurethral resection of the prostate (TURP). The HoLRP technique is an effective and durable surgical alternative to standard TURP.

Aged↗
PubMed2001

Efficacy of topical and systemic itraconazole as a broad-spectrum antifungal agent in mycotic corneal ulcer. A preliminary study.

PURPOSE: To evaluate the efficacy of topical (1%) and systemic itraconazole against common fungi such as Aspergillus and other filamentous fungi that cause mycotic corneal ulcer. METHODS: A prospective randomised, controlled study was done in 54 clinically suspected cases of fungal keratitis of which 44 were culture proven. Half the cases (n=27) with superficial involvement were treated with only topical itraconazole (1%) and the other half were treated with both topical and systemic itraconazole. RESULTS: Aspergillus, Penicillium and Fusarium were the most common fungi isolated. The ulcer resolved in 42 eyes (77%) and 12 eyes (23%) did not respond well to treatment. Four of 12 non-responding eyes were caused by Fusarium species. CONCLUSION: Itraconazole, given either topically or systemically, is effective in treating mycotic corneal ulcers.

Administration, Oral↗
PubMed2000

GreA and GreB proteins revive backtracked RNA polymerase in vivo by promoting transcript trimming.

The GreA and GreB proteins of Escherichia coli show a multitude of effects on transcription elongation in vitro, yet their physiological functions are poorly understood. Here, we investigated whether and how these factors influence lateral oscillations of RNA polymerase (RNAP) in vivo, observed at a protein readblock. When RNAP is stalled within an (ATC/TAG)(n) sequence, it appears to oscillate between an upstream and a downstream position on the template, 3 bp apart, with concomitant trimming of the transcript 3' terminus and its re-synthesis. Using a set of mutant E.coli strains, we show that the presence of GreA or GreB in the cell is essential to induce this trimming. We show further that in contrast to a ternary complex that is stabilized at the downstream position, the oscillating complex relies heavily on the GreA/GreB-induced 'cleavage-and-restart' process to become catalytically competent. Clearly, by promoting transcript shortening and re-alignment of the catalytic register, the Gre factors function in vivo to rescue RNAP from being arrested at template positions where the lateral stability of the ternary complex is impaired.

Bacterial Proteins↗
PubMed2000

Ionizing radiation down-regulates p53 protein in primary Egr-1-/- mouse embryonic fibroblast cells causing enhanced resistance to apoptosis.

In this study, we sought to investigate the mechanism of the proapoptotic function of Egr-1 in relation to p53 status in normal isogenic cell backgrounds by using primary MEF cells established from homozygous (Egr-1(-/-)) and heterozygous (Egr-1(+/-)) Egr-1 knock-out mice. Ionizing radiation caused significantly enhanced apoptosis in Egr-1(+/-) cells (22.8%; p < 0.0001) when compared with Egr-1(-/-) cells (3.5%). Radiation elevated p53 protein in Egr-1(+/-) cells in 3-6 h. However, in Egr-1(-/-) cells, the p53 protein was down-regulated 1 h after radiation and was completely degraded at the later time points. Radiation elevated the p53-CAT activity in Egr-1(+/-) cells but not in Egr-1(-/-) cells. Interestingly, transient overexpression of EGR-1 in p53(-/-) MEF cells caused marginal induction of radiation-induced apoptosis when compared with p53(+/+) MEF cells. Together, these results indicate that Egr-1 may transregulate p53, and both EGR-1 and p53 functions are essential to mediate radiation-induced apoptosis. Rb, an Egr-1 target gene, forms a trimeric complex with p53 and MDM2 to prevent MDM2-mediated p53 degradation. Low levels of Rb including hypophosphorylated forms were observed in Egr-1(-/-) MEF cells before and after radiation when compared with the levels observed in Egr-1(+/-) cells. Elevated amounts of the p53-MDM2 complex and low amounts of Rb-MDM-2 complex were observed in Egr-1(-/-) cells after radiation. Because of a reduction in Rb binding to MDM2 and an increase in MDM2 binding with p53, p53 is directly degraded by MDM2, and this leads to inactivation of the p53-mediated apoptotic pathway in Egr-1(-/-) MEF cells. Thus, the proapoptotic function of Egr-1 may involve the mediation of Rb protein that is essential to overcome the antiapoptotic function of MDM2 on p53.

Adaptor Proteins, Signal Transducing↗
PubMed2000

Induction of apoptosis in glioma cell lines by TRAIL/Apo-2l.

TRAIL/Apo-2L, a novel cytokine, is a member of the tumor necrosis factor (TNF) family and serves as an extracellular signal triggering apoptosis. TRAIL/Apo-2L is capable of killing various transformed cells but not unstimulated primary T cells. In this study, five human glioma cells (U87, U118, U178, U563, and A172) were examined for their susceptibility to the apoptotic effects of TRAIL/Apo-2L. TRAIL/Apo-2L cDNA was isolated by RT-PCR, and recombinant TRAIL/Apo-2L protein was purified by the pMAL-c2 system (New England Biolabs, Beverly, MA). Exposure of A172 cells to bacterially expressed soluble TRAIL/Apo-2L fusion protein at a concentration of 1 microg/ml resulted in significant cell death over a 24-h period. Three experiments were performed to suggest that the TRAIL/Apo-2L killing was through the induction of apoptosis of A172 target cells. In addition, the expression of TRAIL/Apo-2L in different glioma cells was found to be variable, and TRAIL/Apo-2L-induced apoptosis was in a cell type-dependent manner. Some correlation between the susceptibility to TRAIL/Apo-2L and the expression level of one of its cognate receptors, DR4, was observed. In addition, cycloheximide worked synergistically with TRAIL/Apo-2L to induce apoptosis in glioma cells.

Apoptosis↗
PubMed2000

Antiflow of K(0)(s) mesons in 6A GeV Au + Au collisions

We have measured the sideward flow of neutral strange ( K(0)(s)) mesons in 6A GeV Au+Au collisions. A prominent antiflow signal is observed for an impact parameter range ( b less, similar7 fm) which spans central and midcentral events. Since the K(0)(s) scattering cross section is relatively small in nuclear matter, this observation suggests that the in-medium kaon vector potential plays an important role in high density nuclear matter.

Journal Article↗
PubMed2000

Sideward flow in Au+Au collisions between 2A and 8A GeV

Using the large acceptance Time Projection Chamber of experiment E895 at Brookhaven, measurements of collective sideward flow in Au+Au collisions at beam energies of 2A, 4A, 6A, and 8A GeV are presented in the form of in-plane transverse momentum and the first Fourier coefficient of azimuthal anisotropy v(1). These measurements indicate a smooth variation of sideward flow as a function of beam energy. The data are compared with four nuclear transport models which have an orientation towards this energy range. All four exhibit some qualitative trends similar to those found in the data, although none show a consistent pattern of agreement within experimental uncertainties.

Journal Article↗
PubMed2000

Genetic transformation of Coccidioides immitis facilitated by Agrobacterium tumefaciens.

Agrobacterium tumefaciens was used to facilitate genetic transformation of Coccidioides immitis. A gene cassette containing the gene encoding hygromycin phosphotransferase (hph) was cloned into a T-DNA vector plasmid and introduced into A. tumefaciens, and the resultant strain was used for cocultivation with germinated arthroconidia. This procedure produced numerous colonies 60- to >500-fold more resistant to hygromycin than untransformed mycelia. Both polymerase chain reaction and Southern blot analysis of the transformants indicated that all contained hph, usually as a single genomic copy. A transformation frequency of 1 per 10(5) arthroconidia was obtained by varying the germination time prior to cocultivation and altering the bacterium: fungus ratio. This approach requires no special equipment that might complicate biocontainment. Furthermore, transformation does not require digestion of fungal cell walls, further simplifying this procedure. A. tumefaciens-facilitated transformation should make possible the development of tagged mutagenesis and targeted gene disruption technology for C. immitis and perhaps other fungi of medical importance.

Agrobacterium tumefaciens↗
PubMed2000

The functional role of basic patch, a structural element of Escherichia coli transcript cleavage factors GreA and GreB.

The transcript cleavage factors GreA and GreB of Escherichia coli are involved in the regulation of transcription elongation. The surface charge distribution analysis of their three-dimensional structures revealed that the N-terminal domains of GreA and GreB contain a small and large basic "patch," respectively. To elucidate the functional role of basic patch, mutant Gre proteins were engineered in which the size and charge distribution of basic patch were modified and characterized biochemically. We found that Gre mutants lacking basic patch or carrying basic patch of decreased size bind to RNA polymerase and induce transcript cleavage reaction in minimally backtracked ternary elongation complex (TEC) with the same efficiency as the wild type factors. However, they exhibit substantially lower readthrough and cleavage activities toward extensively backtracked and arrested TECs and display decreased efficiency of photocross-linking to the RNA 3'-terminus. Unlike wild type factors, basic patch-less Gre mutants are unable to complement the thermosensitive phenotype of GreA(-):GreB(-) E. coli strain. The large basic patch is required but not sufficient for the induction of GreB-type cleavage reaction and for the cleavage of arrested TECs. Our results demonstrate that the basic patch residues are not directly involved in the induction of transcript cleavage reaction and suggest that the primary role of basic patch is to anchor the nascent RNA in TEC. These interactions are essential for the readthrough and antiarrest activities of Gre factors and, apparently, for their in vivo functions.

Amino Acid Sequence↗
PubMed2000

Muscle abnormalities in juvenile dermatomyositis patients: P-31 magnetic resonance spectroscopy studies.

OBJECTIVE: To characterize metabolic abnormalities in the muscles of children with the juvenile variant of dermatomyositis (JDM) by the use of noninvasive P-31 magnetic resonance spectroscopy (MRS). METHODS: Thirteen patients with JDM (ages 4-16 years) were studied. Biochemical status was evaluated with P-31 MRS by determining the concentrations of the high-energy phosphate compounds, ATP and phosphocreatine (PCr), ratios of inorganic phosphate (Pi) to PCr (Pi:PCr ratio), levels of free cytosolic ADP, and phosphorylation potentials (PPs) during rest, exercise, and recovery. RESULTS: Significant metabolic abnormalities were observed in the thigh muscles of 10 severely affected patients during rest, 2 graded levels of exercise, and recovery. Mean ATP and PCr levels in the muscles of JDM patients were 35-40% below the normal control values (P < 0.003). These data, along with elevated Pi:PCr ratios, higher ADP levels, and abnormal values for PPs, indicated defective oxidative phosphorylation in the mitochondria of diseased JDM muscles. MRS findings were normal in 2 additional patients who had improved with prednisone treatment and in 1 patient who had no muscle weakness (amyopathic variant of JDM). CONCLUSION: JDM patients can be monitored with noninvasive P-31 MRS without sedation. Biochemical defects in energy metabolism are concordant with the weakness and fatigue reported by JDM patients. Quantitative MRS data are useful for evaluating patients and optimizing drug treatment regimens.

Adolescent↗
PubMed2000

Cost-effectiveness of different strategies of cytomegalovirus prophylaxis in orthotopic liver transplant recipients.

Cytomegalovirus (CMV) is an important cause of morbidity and mortality in liver transplant recipients and several different strategies of CMV chemoprophylaxis are in practice. A cost-effective analysis was performed to compare these strategies. A hypothetical cohort of liver transplant recipients was followed up for a year posttransplantation in a Markov model, as they made possible transitions to different states of health with respect to CMV infection and disease. Different strategies of chemoprophylaxis were compared. Cost per patient, yield in terms of gain in quality-adjusted stages, amount of time spent in the state of CMV disease, and CMV-related mortality were the outcome measures compared. Oral ganciclovir administered universally to all transplant recipients was the most favored strategy. Restricting prophylaxis to defined high-risk groups or extending the duration of prophylaxis beyond 3 months did not improve cost-effectiveness. The strategy of short-term, oral ganciclovir-based chemoprophylaxis for CMV in liver transplant recipients is cost-effective by current standards of healthcare interventions.

Administration, Oral↗
PubMed2000

Immobilization stress-induced changes in brain acetylcholinesterase activity and cognitive function in mice.

In the present study, the effect of acute and chronic immobilization stress on brain acetylcholinesterase (AChE) enzyme activity and cognitive function in mice was investigated. Mice were immobilized by strapping for 150 min. One group of mice were only immobilized once (acute stress) while in another group mice were immobilized (150 min) daily for 5 consecutive days (chronic stress). Specific AChE enzyme activity (micromol min(-1)mg(-1)) was estimated by a spectrophotometric method in the whole brain of mice subjected to acute and chronic stress. In the acute stress group, AChE activity (0.24922 +/- 0.011) in the detergent-soluble fraction was found to be significantly decreased in comparison to the control group (0.33561 +/- 0.022). Chronic stress did not cause any significant change in AChE activity in the detergent-soluble fraction. In the salt-soluble fraction, AChE activity was significantly decreased only in the chronic stress group (0.08791 +/- 0.011) as compared to the control group (0.12051 +/- 0.011). A passive avoidance test was used to assess cognitive function. The transfer latency time (TLT) from a light to dark chamber was recorded in the control and acute stress groups (30 min after immobilization is over) on day 1 (Trial I) and the following day (Trial II). The acute stress group showed an increase (178%) in TLT from Trial I to Trial II, which was significantly higher than that of the non-stress control group (75%). In the chronic stress group, Trial I was undertaken 30 min after the last immobilization, i.e. on day 5 and 24 hr later, Trial II. However, the chronically stressed mice showed an increase (70%) in TLT similar to the control group. Thus this study shows that acute immobilization stress may enhance cognitive function in mice which may be attributed to a decrease in AChE activity leading to an increase in cholinergic activity in the brain.

Acetylcholinesterase↗
PubMed2000

Dissimilatory Fe(III) oxide reduction by Shewanella alga BrY requires adhesion.

The Derjaguin-Landau-Verwey-Overbeek (DLVO) theory was used to examine the relationship between adhesion and dissimilatory Fe(III) oxide reduction. Adhesion of Shewanella alga BrY to hydrous ferric oxide (HFO) was correlated with ionic strength and thus was accurately described by the DLVO theory. Reduction of insoluble HFO was also correlated with KCl concentration. In contrast, there was no correlation between soluble Fe(III) reduction and ionic strength. A correlation between HFO reduction rate and adhesion to HFO was observed. These results provide direct evidence that adhesion is requisite for Fe(III) oxide reduction in the absence of soluble electron shuttles.

Bacterial Adhesion↗