Search PubMed⌕ Search

Biomedical subjects

P Das

Publications and source records attributed to P Das.

At least 19 recordsLinked to original sources
PubMed2006

Ultraviolet-visible-near infrared and mid-Fourier transform infrared spectroscopic studies of intermolecular interaction in cholesteryl oleyl carbonate in mesophases.

Ultraviolet-visible-near infrared (UV-Vis-NIR) and Fourier transform infrared (FTIR) spectroscopic studies are presented of molecular association between like molecules of cholesteryl oleyl carbonate, each containing suitable pi-donor (steroid ring C=C) and pi-acceptor (C-O single bonds united with a C=O bond to give a carbonate group) moieties. Frequency shifts and intensity enhancements of donor and acceptor oscillators appear to be governed by reduced mass, vibronic coupling constants, and a few other parameters such as relative change in force constants, etc. Donor-acceptor complex formation is characterized not only by the appearance of new bands in the mid-FTIR spectrum but also by the emergence of a new, intense electronic band centered at approximately 3700 cm(-1), the so-called charge-transfer band, in the UV-Vis-NIR spectrum. This band is strong in the smectic-A and solid phases, but progressively diminishes when temperature is raised to realize the upper end of the cholesteric phase and eventually the isotropic phase. Also, a new, small electronic band at approximately 360 nm, only seen in the entire thermal range of the cholesteric phase, is attributed to the Lifshitz-van der Waals interaction between pretransitional smectic-A domains existing in the cholesteric phase. It is argued that mesophases may owe their thermodynamic stability to both Lifshitz-van der Waals and vibronic coupling (or electron-phonon coupling in extended systems such as smectics and solids) interactions.

Journal Article↗
PubMed2006

Computed tomography screening for lung cancer in Hodgkin's lymphoma survivors: decision analysis and cost-effectiveness analysis.

BACKGROUND: Hodgkin's lymphoma patients have an elevated risk of developing lung cancer and may be targeted for lung cancer screening. We used a decision-analytic model to estimate the potential clinical benefits and cost-effectiveness of computed tomography (CT) screening for lung cancer in Hodgkin's lymphoma survivors. MATERIALS AND METHODS: We developed a Markov decision-analytic model to compare annual low-dose CT screening versus no screening in a hypothetical cohort of patients diagnosed with stage IA-IIB Hodgkin's lymphoma at age 25, with screening starting 5 years after initial diagnosis. We derived model parameters from published studies and the Surveillance, Epidemiology and End Results (SEER) Program, and assumed that stage-shift produces a survival benefit. RESULTS: Annual CT screening increased survival by 0.64 years for smokers and 0.16 years for non-smokers. The corresponding benefits in quality-adjusted survival were 0.58 quality-adjusted life-years (QALYs) for smokers and 0.14 QALYs for non-smokers. The incremental cost-effectiveness ratios for annual CT screening compared with no screening were $34 100/QALY for smokers and $125 400/QALY for non-smokers. CONCLUSIONS: Our analysis suggests that if early promising results for lung cancer screening hold, CT screening for lung cancer may increase survival and quality-adjusted survival among Hodgkin's lymphoma survivors, with a benefit and incremental cost-effectiveness ratio for smokers comparable to that of other recommended cancer screening strategies.

Aged↗
PubMed2006

Long-term results of abdominal salvage surgery following restorative proctocolectomy.

BACKGROUND: This study evaluated outcomes of patients who underwent abdominal salvage ileal pouch redo surgery and identified factors associated with pouch failure following restorative proctocolectomy. METHODS: Data on patients who underwent abdominal salvage surgery in a tertiary referral centre between 1985 and 2003 were collected. Outcomes studied included failure of salvage and bowel function of patients with an intact intestine. RESULTS: One hundred and twelve patients underwent 117 pouch salvage procedures for ulcerative colitis (86), indeterminate colitis/ulcerative colitis (eight), indeterminate colitis/Crohn's disease (three), familial adenomatous polyposis (ten) and other conditions (five). The most common indications for pouch salvage were intra-abdominal sepsis (45 patients), anastomotic stricture (13) and retained rectal stump (35). Median follow-up was 46 (range 1-147) months. Twenty-four patients (21.4 per cent) experienced pouch failure, the incidence of which increased with time. The pouch failed in all patients with Crohn's disease. Successful salvage at 5 years was significantly associated with non-septic (85 per cent) rather than septic (61 per cent) indications (P = 0.016). Frequency of night-time defaecation and faecal urgency improved after salvage surgery (P = 0.036 and P = 0.016 respectively at 5-year follow-up; n = 32). CONCLUSION: Abdominal salvage surgery was associated with a failure rate of 21.4 per cent. A successful outcome was less likely when the procedure was carried out for septic compared with non-septic indications. The rate of pouch failure increased with length of follow-up.

Adolescent↗
PubMed2006

Butachlor degradation in tropical soils: effect of application rate, biotic-abiotic interactions and soil conditions.

The degradative characteristics of butachlor (N-Butoxymethyl-2-chloro-2',6'-diethyla- cetanilide) were studied under controlled laboratory conditions in clay loam alluvial (AL) soil (Typic udifluvent) and coastal saline (CS) soil (Typic endoaquept) from rice cultivated fields. The application rates included field rate (FR), 2-times FR (2FR) and 10-times FR (10FR). The incubation study was carried out at 30 degrees C with and without decomposed cow manure (DCM) at 60% of maximum water holding capacity (WHC) and waterlogged soil condition. The half-life values depended on the soil types and initial concentrations of butachlor. Butachlor degraded faster in AL soil and in soil amended with DCM under waterlogged condition. Microbial degradation is the major avenue of butachlor degradation from soils.

Acetanilides↗
PubMed2006

Vector control in leishmaniasis.

Indoor residual spraying is a simple and cost effective method of controlling endophilic vectors and DDT remains the insecticide of choice for the control of leishmaniasis. However resistance to insecticide is likely to become more widespread in the population especially in those areas in which insecticide has been used for years. In this context use of slow release emulsified suspension (SRES) may be the best substitute. In this review spraying frequencies of DDT and new schedule of spray have been discussed. Role of biological control and environment management in the control of leishmaniasis has been emphasized. Allethrin (coil) 0.1 and 1.6 per cent prallethrin (liquid) have been found to be effective repellents against Phlebotomus argentipes, the vector of Indian kalaazar. Insecticide impregnated bednets is another area which requires further research on priority basis for the control of leishmaniasis. Role of satellite remote sensing for early prediction of disease by identifying the sandflygenic conditions cannot be undermined. In future synthetic pheromons can be exploited in the control of leishmaniasis.

Allethrins↗
PubMed2005

Electrophysiological and behavioral phenotype of insulin receptor defective mice.

The olfactory bulb expresses one of the highest levels of insulin found in the brain. A high level of expression of the concomitant insulin receptor (IR) kinase is also retained in this brain region, even in the adult. We have previously demonstrated in a heterologous system that insulin modulates the voltage-dependent potassium channel, Kv1.3, through tyrosine phosphorylation of three key residues in the amino and carboxyl terminus of the channel protein. Phosphorylation also induces current suppression of the Kv1.3-contributed current in cultured olfactory bulb neurons (OBNs) of rodents. In order to explore the behavioral importance of this kinase-induced modulation of the channel for the olfactory ability of the animal, mice with a targeted-gene deletion of the insulin receptor were electrophysiologically and behaviorally characterized. Mice heterozygous for the insulin receptor kinase (IR+/-) gene performed the same as wild-type (+/+) mice when challenged with a traditional, non-learning-based task to test gross anosmia. There was also no significant difference across the two genotypes in tests designed to measure exploratory behavior or in a battery of systems physiology experiments designed to assess metabolic energy usage (locomotion, ingestive behaviors, weight, oxygen consumption, and respiratory quotient). Object memory recognition tests suggest that IR+/- mice have an impairment in recognition of familiarized objects; IR+/- mice demonstrate poor performance for both short-term (1 h) and long-term (24 h) memory tests in comparison to that of wild-type mice. Electrophysiological experiments indicate that mitral cell neurons cultured from both heterozygous and homozygous-null mice (IR+/- and IR-/-) have an decreased peak current amplitude compared with that recorded for wild-type (+/+) animals matched for days in vitro (DIV). These data indicate that the loss of one allele of the IR kinase gene modifies the electrical phenotype of the mitral cell neurons in the olfactory bulb without a change in gross olfactory ability. Given our findings that there are no significant changes in metabolic balance of the IR (+/-) mice but some impairment in memory retention, future experiments testing for specific olfactory behaviors or functional deficits in IR-/+ mice models of diabetes will need to either be tasks that do not require learning or will require a different model (such as diet-induced diabetes) that may evoke a stronger phenotype.

Animals↗
PubMed2005

Clinical course of thoracic cancers in Hodgkin's disease survivors.

BACKGROUND: Hodgkin's disease survivors have a high risk of subsequently developing thoracic cancers. Our goal was to evaluate the prognosis and treatment outcomes of thoracic cancers after Hodgkin's disease. PATIENTS AND METHODS: Thirty-three patients treated for Hodgkin's disease at Harvard-affiliated hospitals subsequently developed small-cell lung carcinoma, non-small-cell lung carcinoma (NSCLC) or mesothelioma. Information was obtained from medical records about the initial treatment for Hodgkin's disease, any salvage therapy, smoking history, and the stage, histology, treatment and survival for thoracic cancers. RESULTS: Of the 33 patients, 29 (88%) had a history of radiotherapy to the thorax, 17 (52%) had received alkylating chemotherapy, and 24 (73%) had a known history of smoking. The median time between diagnosis of Hodgkin's disease and diagnosis of thoracic cancer was 17.3 years (range 1.2-27.9 years). Among patients with NSCLC and a known stage, 85% presented with stage III or stage IV disease. Among patients whose treatment details were available, 40% underwent surgery, 40% received radiotherapy and 65% received chemotherapy. The median survival was 9 months (range 1-47 months). CONCLUSIONS: Most patients with thoracic cancers after Hodgkin's disease have a history of exposure to risk factors and present at an advanced stage. Patients with thoracic cancers after Hodgkin's disease have a poor survival.

Adolescent↗
PubMed2005

Leishmania donovani: effect of therapy on expression of CD2 antigen and secretion of macrophage migration inhibition factor by T-cells in patients with visceral leishmaniasis.

Visceral leishmaniasis (VL) commonly known as Kala-azar in India is one of the several clinically important infections, where Th1 sub-population of CD4+ T-cells, despite a pre-requisite, fails to express macrophage migration inhibition factor (MIF) and interferon-gamma which both activate the macrophage and coordinate the immune response to intra-cellular Leishmania sp. Expression of CD2 receptors before and after antileishmanial therapy on CD4+ T-cells of VL patients and their corresponding effect on MIF were examined. Before treatment the number of T-cells expressing CD2 was low which incorporated insignificant MIF response. The immunological reconstitution was, however, observed after treatment as manifested through upregulation of CD2+ T-cells with pronounced MIF generation response. The study, therefore, identifies a possible role of CD2 antigen in immunity to VL.

Animals↗
PubMed2005

Beta-amyloid deposition and tau phosphorylation in clinically characterized aged cats.

The current study describes both Abeta and tau abnormalities that accumulate in the brains of aged (16-21 years), but not young (<4 years) clinically characterized cats. Diffuse plaques that were morphologically different from what is typically observed in the human brain could be detected with 4G8 (Abeta17-24) or an Abeta1-42-specific antibody but not with N-terminal Abeta or an Abeta1-40-specific antibody. SELDI-TOF mass spectrometry experiments indicated that cat brain Abeta consisted almost entirely of Abeta1-42. Markers of tau hyperphosphorylation (AT8 and PHF-1) labeled a subset of neurons in two aged animals. In the hilus of the hippocampus, a subset of AT8 positive neurons showed a sprouting morphology similar to that observed in human brain. Western blot analysis with antibodies against hyperphosphorylated tau indicated that tau is hyperphosphorylated in the aged cat and contains many of the same epitopes found in Alzheimer's disease (AD) brain. Thus, the aged cat brain develops AD-related lesions with important morphological and biochemical differences compared to human brain.

Aging↗
PubMed2005

Evaluation of a dot-immunoblot assay for detecting leishmanial antigen in naturally infected Phlebotomus argentipes (Diptera: Psychodidae).

A simple and highly reproducible dot-immunoblot assay was developed to detect leishmanial antigen in Phlebotomus argentipes that were naturally infected with Leishmania donovani. The test was sensitive to as little as 10 ng of antigenic protein (equivalent to the gut content of one laboratory-infected sandfly) and also appeared to be specific, in that it gave a positive result with some P. argentipes (the primary vector of L. donovani in India) and L. donovani but not with P. papatasi or other pathogens. When used to investigate a large number of sandflies collected from two areas of the Indian state of Bihar where visceral leishmaniasis is endemic, the assay appeared sufficiently sensitive and specific to detect the naturally infected insects. The simplicity, reproducibility, high sensitivity and high specificity of the assay should make it useful for field studies, particularly in determining the prevalence of sandfly infection, the local level of transmission, and the impact of vector-control programmes.

Animals↗
PubMed2005

Usefulness of the direct agglutination test in the early detection of subclinical Leishmania donovani infection: a community-based study.

The value of a direct agglutination test (DAT) in the detection of subclinical infections with Leishmania donovani has recently been investigated in the Indian state of Bihar, after the sensitivity and specificity of the test had been determined. When used to screen sera from 108 parasitologically confirmed cases of visceral leishmaniasis, 50 patients with active, non-leishmanial infection, and 641 healthy controls living close to, or distant from, an endemic area, the test was found to be 91.7% sensitive and 100% specific if a titre of 1:800 was used as the threshold for seropositivity. During a longitudinal clinical study in a rural, VL-endemic area of the Indian state of Bihar, the test was used, with 1:800 set as the threshold titre, to determine the baseline prevalence of infection with L. donovani among villagers who, though showing no symptoms of VL, had recently been febrile for at least 2 weeks. The 234 subjects of this study were either VL-case contacts [i.e. members of households in which there were active or cured VL cases (N=78)] or the members of control households with no cases or history of the disease (N=156). The results of DAT at the start of the study indicated that 49 (20.9%) of the subjects--29 (37.2%) of the VL-case contacts and 20 (12.8%) of the other subjects--were seropositive and therefore probably had subclinical infections with L. donovani. During the subsequent 9 months of follow-up, however, only eight of the subjects found seropositive at the start of the study--seven (24.1%) of the seropositive case contacts but only one (5.0%) of the other seropositives--developed symptomatic VL, all by month 6 of the follow-up. Compared with their neighbours, therefore, individuals who shared households with active or cured cases of VL appeared at greater risk not only of L. donovani infection (indicating focal transmission) but also of developing symptomatic disease once infected. Curiously, among the seropositive case contacts, those from the households that harboured active cases of VL at the baseline survey were less likely to develop symptomatic VL during the 9 months of follow-up than those from households that harboured only cured cases (18.8% v. 30.8%). The wide-spread use of DAT could allow the detection and early treatment of latent L. donovani infections and so contribute to the elimination of VL, at least as a public-health problem, from India.

Agglutination Tests↗