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Biomedical subjects

S Chakravorty

Publications and source records attributed to S Chakravorty.

30 records · Page 2Linked to original sources
PubMed1993

Value of a single Widal test in the diagnosis of typhoid fever.

Results of a single Widal test in patients with bacteriologically confirmed typhoid fever (116), clinically suggestive but culture negative fever (170) and non-typhoidal febrile illness (98) and in normal control children (54) were analysed. Positive Widal test (antibody titre against S. typhi O antigen of 1:160) was recorded in 61.2 per cent of patients with bacteriologically confirmed typhoid fever and in 58.8 per cent with culture negative but clinically suggestive typhoid fever. In contrast, the same titre was observed in 10.2 per cent patients with other febrile illnesses of known etiology and in 1.8 per cent of normal children. Differences in the positivity of Widal test in patients with bacteriologically confirmed typhoid fever and clinically suggestive but culture negative fever were highly significant (P < 0.000001) when compared to that of patients with non-typhoidal febrile illnesses and normal controls. High specificity and positive predictive value in 1:160 dilution makes the Widal test acceptable as a diagnostic tool.

Antibodies, Bacterial↗
PubMed1992

Effect of endosulfan (thiodan) on vitellogenesis and its modulation by different hormones in the vitellogenic catfish Clarias batrachus.

This programme was planned in order to study the reproductive dysfunction caused by endosulfan in the fish Clarias batrachus with special reference to vitellogenesis. Vitellogenin was measured by radioimmunoassay. Endosulfan caused a drastic reduction in the plasma vitellogenin which was partially reversed by estradiol-17 beta (E2) in intact and ovariectomized fish. Hormones in combination were more effective than any single hormone in overcoming the impact of endosulfan. Triiodothyronine (T3), ovine luteinizing hormone releasing hormone (oLHRH) were effective in minimizing the effect of endosulfan whereas cortisol (F) and ovine somatotropic hormone (oStH) did not reduce the effect of endosulfan. Amongst the combined hormone treatments, E2 + oLHRH and E2 + T3 were the most potent in overcoming the effect of endosulfan on vitellogenesis.

Animals↗
PubMed1989

Malignant mesothelioma in the young (with prosthetic aortic valve an unusual association).

A case of malignant mesothelioma (MM) in a 15 year old boy is reported. He had a prosthetic aortic valve implanted in 1980 at our centre for rheumatic aortic regurgitation. Fever, weight loss and chest pain as initial symptoms suggested possibility of prosthetic valve endocarditis. Dysphagia as another initial symptom was interesting and caused further diagnostic dilemma. Role of Computerised Tomography (CT) scan in diagnosis of MM is highlighted.

Adolescent↗
PubMedDate not supplied

The association of suicide attempts and comorbid depression and substance abuse in psychiatric consultation patients.

Substance abuse has been associated with attempted suicide and suicide. Few studies have examined the prevalence and associations of combined depression and substance abuse in suicide attempters. A chart review study of 1136 adult general hospital patients referred for psychiatric consultation between 1995 and 1998 was conducted to assess this further. Among 371 cases with self-harm, 311 (84%) attempted suicide. Suicide attempters were younger and diagnosed more often with comorbid substance abuse than patients without self-harm. Depressive disorders were found in 59% and substance abuse disorders in 46%. Comorbid depression and substance abuse was the most frequent category in suicide attempters, i.e., in 37%. Self-reported suicide intent was associated with increasing age, male gender, and comorbid depression and substance abuse. The suicide rate in suicide attempters was 322 per 100,000 patient-years, and 131 per 100,000 in consultation patients without self-harm. It is concluded that comorbid depression and substance abuse is associated with attempted suicide in psychiatric consultation patients. Suicide attempters should be thoroughly assessed for substance abuse. The increased suicide rate in psychiatric consultation patients with and without suicide attempts warrants further research.

Adult↗
PubMedDate not supplied

Improved AMBER torsional parameters for the N-N rotational barrier in diacylhydrazines.

The structure and rotational barrier for substituted diacylhydrazines are of significant interest given the role this functionality plays in peptidomimetics and ecdysone agonists, the latter of which have application as extremely selective insecticides. Ab initio calculations show that the lowest energy conformations are typically nonplanar with essentially perpendicular nitrogen lone pairs. Molecular mechanics calculations using the AMBER force field in MacroModel yield minima and rotational barriers that are both quantitatively and qualitatively inconsistent with the ab initio results. In this work the AMBER N-N rotational barriers for all configurations of the parent, methyl and di-methyl substituted diformylhydrazines have been fitted to MP2/6-31 + G relative energies. The resulting AMBER torsional parameters have been validated by calculating the rotational barriers for N-t-butyl substituted diformylhydrazine, dibenzoylhydrazine and an azadipeptide. In each case the new AMBER rotational barriers compare favorably with the corresponding MP2 calculated rotational barriers.

Ecdysone↗
PubMedDate not supplied

Diversity and coverage of structural sublibraries selected using the SAGE and SCA algorithms.

It is often impractical to synthesize and test all compounds in a large exhaustive chemical library. Herein, we discuss rational approaches to selecting representative subsets of virtual libraries that help direct experimental synthetic efforts for diverse library design. We compare the performance of two stochastic sampling algorithms, Simulating Annealing Guided Evaluation (SAGE; Zheng, W.; Cho, S. J.; Waller, C. L.; Tropsha, A. J. Chem. Inf. Comput. Sci. 1999, 39, 738-746.) and Stochastic Cluster Analysis (SCA; Reynolds, C. H.; Druker, R.; Pfahler, L. B. Lead Discovery Using Stochastic Cluster Analysis (SCA): A New Method for Clustering Structurally Similar Compounds J. Chem. Inf. Comput. Sci. 1998, 38, 305-312.) for their ability to select both diverse and representative subsets of the entire chemical library space. The SAGE and SCA algorithms were compared using u- and s-optimal metrics as an independent assessment of diversity and coverage. This comparison showed that both algorithms were capable of generating sublibraries in descriptor space that are diverse and give reasonable coverage (i.e. are representative) of the original full library. Tests were carried out using simulated two-dimensional data sets and a 27 000 compound proprietary structural library as represented by computed Molconn-Z descriptors. One of the key observations from this work is that the algorithmically simple SCA method is capable of selecting subsets that are comparable to the more computationally intensive SAGE method.

Journal Article↗
PubMedDate not supplied

Nasal nitric oxide: a comparison of measurement techniques.

Nasal nitric oxide measurement may be a surrogate marker of upper airway inflammation. There is, however, no standardized measurement technique; and this led us to examine measurement techniques for acceptability and reproducibility. In five subjects we examined the flow dependence of nasal NO. In 13 healthy volunteers, nasal NO was measured on-line by five methods: 1) Tidal nasal and oral breathing: NO sampling during exclusive nasal followed by exclusive oral tidal breathing; 2) Fixed flow exhalation: NO sampling during exclusive nasal followed by exclusive oral exhalation at 100 mL/second from total lung capacity; 3) Nasal-oral aspiration: air aspirated from the mouth via both nares at 100 mL/second with glottis closure; 4) Aspiration from one nares: air aspirated from one nares at 3.3 mL/second using nitric oxide analyzer sample line with velum closure; 5) Nasal Insufflation: NO sampled at one nares as air insufflated into the other nares at a flow of 100 mL/second with velum closure. Acceptability of all methods was assessed by subjects and technicians. Nasal NO concentration showed a significant inverse correlation with transnasal flow rate. All methods showed excellent reproducibility as assessed by the intraclass correlation coefficient except tidal breathing, which showed highly variable breath-to-breath NO levels, although mean breath values were reproducible. Mean nasal NO concentrations with methods 1, 2, 3, 4, and 5 were 32.1, 50.2, 62.8, 1381, and 60.0 ppb, respectively. Velum closure was not always achieved in methods 4 and 5, whereas methods 1 and 2 required separate nasal and oral procedures. Method 5 had reduced acceptability. NO concentrations were similar with methods that used the same airflow (2, 3, and 5). Nasal NO can be sampled in different ways with excellent reproducibility. In view of the flow dependence of nasal NO, it is vital to use a constant flow rate, and lower airway NO contribution must be excluded or subtracted. The fixed flow exhalation appears to be the preferred method as it is highly reproducible and acceptable.

Analysis of Variance↗
PubMedDate not supplied

Reproducibility of acoustic rhinometry and rhinomanometry in normal subjects.

The reproducibility of nasal patency measurements was assessed by acoustic rhinometry and active rhinomanometry using previously described Toronto methodologies. Six subjects with normal upper airways were tested with both procedures on six separate occasions within a 2-month period. Topical decongestant was applied to minimize the effects of mucosal variation on the nasal airway. The mean coefficients of variation (mean +/- s.d; %) over time of the measurements were 8.1 +/- 4.1 and 9.7 +/- 5.2 for minimal unilateral cross-sectional area and 4.8 +/- 1.8 and 5.5 +/- 3.5 for nasal volume (0-5 cm) of the right and left sides, respectively. For active rhinomanometry, the mean coefficients of variation (mean +/- s.d.; %) over time of the measurements were 15.9 +/- 7.3, 12.9 +/- 4.6, and 8.5 +/- 2.8 for right, left and combined nasal airflow resistance. The intraclass correlation coefficient was 0.76, 0.70, and 0.96 for right, left, and combined nasal resistance, 0.91 and 0.87 for right and left minimal cross sectional area, and 0.86 and 0.69 for right and left nasal volumes, respectively, also confirming a high level of reproducibility for both methods. In conclusion, performed by an experienced operator under controlled circumstances, the reproducibility of both methods of nasal patency assessment compared favorably with many widely accepted clinical tests.

Acoustics↗
PubMedDate not supplied

Fatal atypical mycobacterial infection in a cardiac transplant recipient.

A 37-year-old female underwent heart transplantation for giant cell myocarditis. The patient died within three-and-a-half months of cardiac transplantation. Postmortem specimens from the heart and lung showed multiple necrotizing granulomas with numerous acid-fast bacilli. Polymerase chain reaction done on both the postmortem samples confirmed the presence of atypical mycobacterial infection. This fatal case of atypical mycobacteriosis in a cardiac transplant patient is reported for its rarity.

Adult↗