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Biomedical subjects

N Choudhury

Publications and source records attributed to N Choudhury.

At least 19 recordsLinked to original sources
PubMed2006

Smooth muscle of telokin-deficient mice exhibits increased sensitivity to Ca2+ and decreased cGMP-induced relaxation.

Cyclic nucleotides can relax smooth muscle without a change in [Ca2+]i, a phenomenon termed Ca2+ desensitization, contributing to vasodilation, gastrointestinal motility, and airway resistance. The physiological importance of telokin, a 17-kDa smooth muscle-specific protein and target for cyclic nucleotide-induced Ca2+ desensitization, was determined in telokin null mice bred to a congenic background. Telokin null ileal smooth muscle homogenates compared to wild type exhibited an approximately 30% decrease in myosin light-chain phosphatase (MLCP) activity, which was reflected in a significant leftward shift (up to 2-fold at pCa 6.3) of the Ca2+ force relationship accompanied by an increase in myosin light-chain phosphorylation. No difference in the Ca2+ force relationship occurred in telokin WT and knockout (KO) aortas, presumably reflecting the normally approximately 5-fold lower telokin content in aorta vs. ileum smooth muscle. Ca2+ desensitization of contractile force by 8-Br-cGMP was attenuated by 50% in telokin KO intestinal smooth muscle. The rate of force relaxation reflecting MLCP activity, in the presence of 50 microM 8-Br-cGMP, was also significantly slowed in telokin KO vs. WT ileum and was rescued by recombinant telokin. Normal thick filaments in telokin KO smooth muscles indicate that telokin is not required for filament formation or stability. Results indicate that a primary role of telokin is to modulate force through increasing MLCP activity and that this effect is further potentiated through phosphorylation by cGMP in telokin-rich smooth tissues.

Actin Cytoskeleton↗
PubMed2005

4 years' experience of head and neck tuberculosis in a south London hospital.

In a south London department of otorhinolaryngology and head and neck surgery, 33 cases of tuberculosis were diagnosed in 4 years. The most common presentation was cervical adenitis (58%) and in some cases the initial investigations suggested malignant disease. Most of the patients were of non-British origin but none proved to be HIV seropositive. Fine-needle aspiration was positive for tuberculosis in 7 of 19 patients. 21 patients required a surgical procedure for diagnosis.

Adult↗
PubMed2005

Effect of pre-storage gamma irradiation on red blood cells.

BACKGROUND & OBJECTIVE: The irradiation of blood components has received increased attention due to increasing categories of patients eligible to receive such blood to prevent transfusion-associated graft versus host disease. Irradiation leads to enhancement of storage lesions, which could have deleterious effects when such blood is transfused. The aim of the present study was to assess the biochemical changes during conventional preservation of irradiated and non-irradiated whole blood. METHODS: Ten units of whole blood were taken from healthy donors and divided into two parts. One aliquot was subjected to gamma irradiation and then stored under conventional blood banking conditions. Sampling was done from these irradiated and non-irradiated blood bags and tests for free plasma haemoglobin, plasma potassium and lactate dehydrogenase (LDH) were performed. RESULTS: A progressive increase in the mean values of plasma Hb, K+ and LDH was seen in both the groups. The increase was statistically significant. INTERPRETATION & CONCLUSION: Our findings indicated that the gamma irradiation of blood resulted in increased plasma haemoglobin, potassium and LDH. These biochemical changes might not have clinical significance when irradiated blood is transfused to a select group of patients. There is a need for further in vivo studies to follow up the consequences of transfusion of irradiated blood in patients.

Blood Preservation↗
PubMed2004

Epistaxis and oral anticoagulant therapy.

Epistaxis in the anticoagulated patient poses a complicated management problem, which requires interdisciplinary collaboration. The aetiology of the majority of cases of epistaxis remains idiopathic, but an ageing population and the prevalence of ischaemic heart disease and peripheral vascular disease has meant that there are increasing numbers of patients on long term oral anticoagulant therapy. This has led to a concomitant increase in the incidence of complications experienced. We have reviewed the available relevant literature and guidelines in the current management practice in this scenario. In light of this, we propose a more standardised algorithm for the management of epistaxis in this challenging group of patients.

Administration, Oral↗
PubMed2003

Cord blood from collection to expansion: feasibility in a regional blood bank.

This article reviews the various aspect of the experimental phase preceding the establishment of an umbilical cord blood (UCB) bank within a regular blood bank, a situation totally different from that of de novo establishing a cord blood bank having human and financial resources. An ethically approved two-year study has been conducted to determine the technical feasibility, and the practical problems that might be encountered such as public compliance, the additional workload, introduction of new activities ranging from collection and processing to progenitor expansion, infectious disease testing, development of a quality control system, record keeping and documentation, development of specific procedures and definitions of requirements. The cost benefit aspect, which will ultimately depend on the frequency of units release, was not considered in this study.

Blood Banking↗
PubMed2003

Transmission of filarial infection through blood transfusion.

Microfilariae can be transmitted by blood transfusion and they may be circulated in the recipient's blood but they do not develop into adult worms. Mortality associated with transfusion associated filarial infection is not documented but it may give rise to morbidity in transfusion recipients in terms of allergic reaction. The present study was carried out to investigate the association of post transfusion reactions and filarial infections in an endemic area. About 11,752 transfusion recipients were followed up and in 15 months period, 47 (0.4%) post transfusion reactions (PTR) were reported. Routine investigations for post transfusion reaction were carried out in all 47 patients and their respective blood donor. Moreover, blood culture, microfilaria detection by concentration technique, filarial antibody and antigen detection (both by ELISA) were done in all subjects. Out of 47 patients showing post transfusion reaction, 29 (61.7%) patients developed allergic reaction. Eighteen (38.3%) patients having allergic reaction did not have previous history of blood transfusion and 14 (29.8%) of them received transfusion from blood donors who was either positive for microfilaria, filarial antigen or antibody. Microfilaremia was demonstrated in 4 (8.5%) patients and 5 (10.6%) blood donors. Microfilaria was concurrently present in 2 patients and their respective donors. Filarial antibody was detected in 27 (56.5%) patients and 26 (55.3%) blood donors but microfilaria was detected in 3 (6.4%) and 4 (8.5%) subjects, respectively. Antigen detection test correlated with microfileraemic state of subjects. The result shows that transfusion associated filarial infection may be a probable cause for transfusion-associated morbidity in endemic areas. In 14 (29.8%) patients having allergic reactions, the probable cause was transfusion-associated filarial infection. Filarial antigen detection test was found to be more useful in detecting infections. Blood donors with active history of filarial infection should be deferred from donating blood. Filarial antigen detection test may be employed as screening test for blood donors, if possible.

Animals↗
PubMed2001

Adsorption of Lennard-Jones fluid mixture in a planar slit: a perturbative density functional approach.

A simple perturbative density functional approach is employed to investigate the adsorption behavior of a model Lennard-Jones fluid confined in a slitlike pore. Adsorption of one-component fluid as well as two-component fluid mixtures in varying pore sizes has been investigated. The results on the density profiles and the excess adsorption obtained from this theory are found to be in overall good agreement with the available computer simulation results. The results are also compared with the same from some recent weighted density based calculations.

Journal Article↗
PubMed2001

Transfusion transmitted diseases.

Transfusion transmitted disease (TTD) is a major challenge to the transfusion services all over the world. The problem of TTD is directly proportionate to the prevalence of the infection in the blood donor community. In India, hepatitis B/C, HIV, malaria, syphilis, cytomegalo virus, parvo-virus B-19 and bacterial infections are important causes of concern. Hepatitis B and C infections are prevalent in India and carrier rate is about 1-5% and 1%, respectively. Post transfusion hepatitis B/C is a major problem in India (about 10%) because of low viraemia and mutant strain undetectable by routine ELISA. HIV prevalence among blood donors is different in various parts of the country. It may not be so alarming as projected by some agencies. In one study from north India, confirmed HIV positivity was found in 0.2/1000 blood donor. Post transfusion CMV is difficult to prevent but use of leukocyte filters may help to reduce it significantly. Parvo virus B-19 infection in blood donors is 39.9% which may increase morbidity in multitransfused or immunocompromised patients. Current symphilis tests may not be sensitive but it should be continued to exclude high-risk donors. Malaria is a real problem for India due to the lack of a simple and sensitive screening test. Incidence of bacterial contamination is greatly reduced due to improved collection/preservation techniques and use of antibiotics in patients. However, proper vigilance and quality control is needed to prevent this problem. Total dependence of altruistic repeat voluntary donors and use of sensitive laboratory tests may help Indian blood transfusion services to reduce incidences of TTDs.

Bacterial Infections↗
PubMed2001

Differential patterns of development: the interaction of birth weight, temperament, and maternal behavior.

A short-term longitudinal study of 83 families compared patterns of development between full-term small for gestational age (SGA) and normal birth weight (NBW) infants. Data were collected on infant temperament and maternal interaction at 3 and 6 months, and infant developmental outcomes at 6 months in order to investigate relationships between infant and maternal behavior, and developmental outcomes as a function of birth weight. Findings revealed few differences between SGA and NBW groups. However, the relations between infant temperament and maternal behavior varied as a function of birth weight and home environment. Specifically, more positive home environments were associated with higher ratings of maternal behavior and lower levels of infant negative reactivity for SGA but not for NBW infants. In addition, higher negative reactivity was related to lower performance on both the mental and psychomotor scales of the Bayley Scales of Infant Development (BSID), with stronger associations reported for SGA infants than for NBW infants.

Birth Weight↗
PubMed2000

True HIV seroprevalence in Indian blood donors.

The National AIDS Control Organization (NACO), the apex body for controlling AIDS in India, projected that HIV seroprevalence would increase from 7/1000 in 1995 to 21.2/1000 in 1997. A high incidence (8.2%) of HIV was observed in blood donors. This study was carried out to find out the true HIV positivity in Indian blood donors. Blood donors from our centre were followed for more than 5 years to determine the true HIV seroprevalence and our result was compared with similar studies from India. Voluntary and relative blood donors who visited the SGPGIMS, Lucknow, since 1993 to June 1998 were included. They were screened for HIV 1/2 by ELISA kits (WHO approved). First-time HIV-positive samples were preserved frozen for further study (stage-I). They were repeated in duplicate and retested with other kits. If found positive, the sample was labelled as ELISA positive (stage-II). ELISA-positive samples were confirmed by Western Blot (WB) at stage-III. A total of 65 288 donors were included and 834 (12.8/1000) were reactive at stage-I. But 1.1/1000 donors were found to be ELISA positive at stage-II, and 0.28/1000 donors were positive by WB at stage-III. The 'seropositivity' rate from the NACO was significantly (P < 0.001) higher than our study. There were five similar Indian studies and seropositivity rate varied from 0.72/1000 (using ELISA and WB) to 5.5/1000 (using ELISA alone). The 'seropositivity' rate from the NACO was significantly (P < 0.001) higher than all these studies. HIV seroprevalence in the present study is lower (P < 0.001) than other Indian figures. The present and other studies confirmed that the projected HIV seroprevalence (82/1000) in Indian blood donors was high. The NACO result was based on one-time ELISA screening reports from zonal blood testing centres which also receive samples from paid donors donating in commercial blood banks. The HIV prevalence of blood donors (and national prevalence) is to be reassessed.

AIDS Serodiagnosis↗
PubMed2000

Blood loss in orthotopic liver transplantation: a retrospective analysis of transfusion requirements and the effects of autotransfusion of cell saver blood in 164 consecutive patients.

Liver transplantation is associated with excessive blood loss. In order to identify factors influencing blood loss and to provide a basis for a pilot study to evaluate recombinant activated factor VII as a haemostatic agent, a retrospective study was performed in 164 consecutive patients with cholestatic or noncholestatic liver disease, who underwent orthotopic liver transplantation at a single centre between 1989 and 1996. Transfusion of allogeneic and autologous (cell saver) blood was used as a measurement of blood loss. Transfusion requirements were associated with age, gender, primary disease, Child-Pugh classification, serum levels of activated partial thromboplastin time, antithrombin III, urea and creatinine, platelet number, year of transplantation, length of cold ischaemia time and autologous blood transfusion. Of these variables, Child-Pugh classification (P = 0.001), urea (P = 0.0007), year of transplantation (P = 0.002), cold ischaemia time (P = 0.01) and autologous blood transfusion (P < 0.0001) were independent predictors of transfusion requirements by multivariate analysis. Thus, blood loss and transfusion requirements depend primarily on the severity of liver disease, quality of the donor liver, experience of the transplantation team and use of autologous (cell saver) blood transfusion. These findings emphasize the need for appropriate drug therapy and a critical reappraisal of current transfusion policy.

Adult↗
PubMed2000

Transfusion safety in developing countries and the Indian scenario.

The AIDS pandemic has brought into focus the importance of safe blood transfusion. The management of an effective transfusion service is an expensive endeavour even in the most developed countries, and is therefore a monumental challenge for developing countries with limited budgets and other priorities. HIV prevalence in the Indian population has shown a steady rise from 0.5% in 1990 to 1.2% in 1997 with the highest prevalence in cities. When the HIV infection was discovered in India in 1986, the health authorities set up the National AIDS Control Organisation (NACO) with a primary focus on ensuring a safe blood supply. NACO was funded by the World Bank and technically supported by WHO. The supreme Court of India has also taken up the issue of blood safety by banning paid donations by the end of 1997 and established the autonomous National Blood Transfusion Council and the State Transfusion Councils. The Drugs Controller of India and State F.D.A. have issued licences to all blood banks to streamline them after all requirements are met. However, there are a number of blood banks which are operating without licences. While India collects three million units of blood, barely 10% is available as blood components, and only a percentage of the blood is being screened for infectious markers. Nevertheless, there is a general recognition that an improved transfusion service is required in India.

Blood Transfusion↗
PubMed1999

Growth stimulation by serum in Entamoeba histolytica is associated with protein tyrosine dephosphorylation.

Very little protein tyrosine phosphorylation was observed in growing (exponential-phase) Entamoeba histolytica cells by immunoblotting and quantitative immunofluorescence. After 1 h of serum deprivation, two proteins (42 and 38 kDa in SDS-PAGE) were tyrosine phosphorylated and two more proteins (96 and 63 kDa) also showed tyrosine phosphorylation when examined after 4 h of serum deprivation. Intense enhancements of anti-phosphotyrosine immunofluorescence levels were observed during this period of serum withdrawal. Membrane-associated tyrosine kinase activity reached a peak (3.5-fold increase) 1 h after serum deprivation and decreased thereafter reaching a basal level by 2 h of serum deprivation. Interestingly, tyrosine kinase activities remained unaffected by serum stimulation (2-60 min) of serum-deprived cells. Also, during this period of serum stimulation tyrosine phosphorylated proteins of serum-deprived cells were dephosphorylated. Tyrosine phosphatase activities were suppressed during serum deprivation and on serum addition to serum-deprived cells tyrosine phosphatase activities increased significantly. Our data attest that protein tyrosine phosphorylation was associated with growth inhibition of E. histolytica and serum stimulation of E. histolytica produced tyrosine phosphatase activation and protein tyrosine dephosphorylation.

Animals↗
PubMed1998

Monounsaturated oils do not all have the same effect on plasma cholesterol.

Evidence assembled here indicates that when olive oil forms a major part of dietary fat in controlled human experiments, total and LDL-cholesterols are somewhat higher than when the same amount of fat is one of the modern predominantly monounsaturated oils: low erucic rapeseed or high oleic sunflower oil. Oils rich in monounsaturated fatty acids thus do not all have the same effect on plasma cholesterol. This phenomenon is explicable by consideration of the content of other fatty acids and the non-saponifiable fractions of the different monounsaturated oils. It helps to explain the discrepancy that has existed between the classic experiments (using olive oil), which found monounsaturated oils 'neutral', and some of the more recent experiments which found them more cholesterol-lowering than carbohydrates. Four published meta-analyses are reviewed. The three which included most of the published experiments show that monounsaturated fatty acids (MUFA) have less plasma cholesterol-lowering effect than polyunsaturated fatty acids.

Cholesterol↗
PubMed1998

Serological monitoring of thalassaemia major patients for transfusion associated viral infections.

A total of 39 patients with thalassaemia major who received multiple blood transfusions were followed up clinically and serologically for 3 successive years (1993, 1994, 1995). They were screened for hepatitis B surface antigen (HBsAg), and antibodies to hepatitis B core (HBc-total), hepatitis C virus (HCV), human immunodeficiency virus I and II (HIV-I/II) and cytomegalovirus (CMV-total). In spite of transfusing HBsAg screened (by third generation ELISA) blood from voluntary non-remunerated donors, there was a significant increase of HBsAg positivity (P < 0.001) from 17.9 per cent (1993) to 35.9 per cent (1994) to 69.2 per cent (1995). This was probably due to the prevalence of undetectable HBV infection in the population. Anti HBc was present in 17 (43.6%), 14 (35.9%) and 16 (41%) patients in consecutive years. An increase in the units of blood transfused was observed every year. Blood units were not screened for anti HCV antibodies but a gradual increase in positivity [9 (23%), 12 (30.7%) and 14 (35.9%) patients] was seen in consecutive years. Anti-HIV antibodies were found in a 16 yr old male who was included in the study without any clinical evidence of AIDS. Anti CMV antibody was found in 30 (76.9%), 32 (82%) and 29 (74.3%) patients without any apparent clinical infection. Some patients showed change of antibody pattern (from negative to positive or vice versa) and a few patients showed inconsistent results probably due to immune modulation. Recruitment of 'repeat' non-remunerated voluntary blood donors may reduce the risk of high HBV transmission.

Adolescent↗
PubMed1997

Expression of recombinant human ceruloplasmin--an absolute requirement for splicing signals in the expression cassette.

We report the successful expression of recombinant human ceruloplasmin which was made possible by inclusion of splicing signals in the expression vector. Ceruloplasmin cDNA expressed from the vector pNUT in baby hamster kidney cells gave protein yields of 0.03 mg/l which increased to 15 mg/l with splicing signals present. The defect in expression from the intronless cDNA is due to complete retention of ceruloplasmin mRNA in cell nuclei. The block to cytoplasmic export is alleviated by splicing signals, allowing full expression of the mRNA.

Animals↗
PubMed1997

Comparison of plasma lipids and vitamin E in young and middle-aged subjects on potato crisps fried in palmolein and highly oleic sunflower oil.

We previously found no difference in healthy young adults' plasma cholesterols between palmolein and olive oil as the major dietary lipid, although the former is high in palmitic acid (16:0) but the latter in oleic acid (18:1 cis). In the experiment reported here we compared the effects of palmolein against another monounsaturated oil, highly oleic sunflower oil (HOSO), on plasma cholesterol in both young and middle-aged healthy adults. The test oils were provided as frying oil of potato crisps (150 g/day in men; 100 g/day in women) against low-fat background diets in free-living motivated volunteers. The design was a randomised double-blind 4-week/3-week crossover trial. Compliance was monitored with continuous dietary diaries and by measuring (fasting) plasma lipid fatty-acid pattern. Plasma lipids and vitamin-E compounds were measured at the start and twice at the end of each test period. In combined young plus older subjects (n = 42) mean plasma total and low-density-lipoprotein cholesterol (LDL-c) values were both 7% (significantly) lower on HOSO than on palmolein, but because high-density-lipoprotein cholesterol (HDL-c) was also 5% lower, the LDL-c/HDL-c ratio was only 3% lower on HOSO than on palmolein. The difference between the present results with HOSO and previous results with olive oil both compared against palmolein suggest that olive oil is associated with higher plasma cholesterols than other monounsaturated oils. In both the young and older subgroup, LDL-c was lower on HOSO but because HDL-c moved down too in the young subgroup, the LDL-c/HDL-c ratio was lower on HOSO only in the older subjects. Palmolein has an unusual pattern of E vitamins, with a high content of tocotrienols, notably the gamma-isomer. Unlike alpha-tocopherol however, there was no sign of these tocotrienols in subjects' plasmas.

Adult↗