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Biomedical subjects

S Subramanian

Publications and source records attributed to S Subramanian.

At least 19 recordsLinked to original sources
PubMed2004

Tailored sinc pulses for uniform excitation and artifact-free radio frequency time-domain EPR imaging.

A method to generate shaped radiofrequency pulses for uniform excitation of electron spins in time-domain radio frequency (RF) electron paramagnetic resonance (EPR) imaging is presented. A commercial waveform generator was integrated with the transmit arm of the existing time-domain RF-EPR spectrometer to generate tailored excitation pulses with sub-nano second resolution for excitation with a 90 degrees flip-angle. A truncated sinc [sin(x)/x] pulse, tailored to compensate for the Q-profile (RF frequency response) of the resonator, was shown to yield images from phantom objects as well as in vivo images, with minimal distortion. These studies point to the advantages in using shaped sinc pulses to achieve improved uniform excitation over a relatively wide bandwidth region in time-domain RF-EPR imaging (RF-FT-EPRI).

Animals↗
PubMed2004

Synthesis, Fourier transform infrared and Raman spectra, assignments and analysis of N-(phenyl)- and N-(chloro substituted phenyl)-2,2-dichloroacetamides.

N-(phenyl)-2,2-dichloroacetamide (NPA) and N-(chloro substituted phenyl)-2,2-dichloroacetamides of the configuration XyC6H(5-y)-NHCO-CHCl2 (where, X = Cl and y = 1, 2 and 3) were synthesised and the Fourier transform infrared (FTIR) and Fourier transform Raman (FT-Raman) spectra of the compounds were recorded and analysed. The FTIR spectra of all the compounds were recorded in a Bruker IFS 66V spectrometer in the range of 4000-400 cm(-1) and the FT-Raman spectra were also recorded in the same instrument in the region 3500-100 cm(-1). The variation of an amide bond (-NHCO-) parameters with the substitution of the chlorine atom in the phenyl group and the mixing of different normal modes are discussed with the help of potential energy distribution (PED) calculated through normal co-ordinate analysis.

Acetamides↗
PubMed2004

FTIR and FTR spectral studies of 2-amino-6-bromo-3-formylchromone.

FTIR and FT-Raman spectra of 2-amino-6-bromo-3-formylchromone (ABFC) have been recorded, using Bruker IFS 66V spectrometer. A detailed vibrational spectral analysis carried out and assignments of the observed bands have been proposed on the basis of fundamentals, overtones and combinations, by assuming C(S) point group symmetry. A normal coordinate analysis has been performed to characterise the vibrational fundamentals in terms of potential energy distribution (PED).

Bromine↗
PubMed2004

The dynamics of Wuchereria bancrofti infection: a model-based analysis of longitudinal data from Pondicherry, India.

This paper presents a model-based analysis of longitudinal data describing the impact of integrated vector management on the intensity of Wuchereria bancrofti infection in Pondicherry, India. The aims of this analysis were (1) to gain insight into the dynamics of infection, with emphasis on the possible role of immunity, and (2) to develop a model that can be used to predict the effects of control. Using the LYMFASIM computer simulation program, two models with different types of immunity (anti-L3 larvae or anti-adult worm fecundity) were compared with a model without immunity. Parameters were estimated by fitting the models to data from 5071 individuals with microfilaria-density measurement before and after cessation of a 5-year vector management programme. A good fit, in particular of the convex shape of the age-prevalence curve, required inclusion of anti-L3 or anti-fecundity immunity in the model. An individual's immune-responsiveness was found to halve in approximately 10 years after cessation of boosting. Explanation of the large variation in Mf-density required considerable variation between individuals in exposure and immune responsiveness. The mean life-span of the parasite was estimated at about 10 years. For the post-control period, the models predict a further decline in Mf prevalence, which agrees well with observations made 3 and 6 years after cessation of the integrated vector management programme.

Adolescent↗
PubMed2004

Vector survival and parasite infection: the effect of Wuchereria bancrofti on its vector Culex quinquefasciatus.

This paper investigates a cohort of 2187 laboratory reared Culex quinquefasciatus fed on 69 human volunteers, including 59 persons with different levels of Wuchereria bancrofti microfilariae and 10 without microfilaria. Mosquitoes were followed until death. Mosquito survival was analysed in relation to the level of microfilaria in the human and larval count in the dead mosquito. Vector mortality during the extrinsic incubation period (12 days post-engorgement) was significantly higher in mosquitoes fed on microfilaraemic volunteers (50%) than in those fed on amicrofilaraemics (29%). Both the percentage infected and the geometric mean parasite density was significantly higher among mosquitoes which died before 13 days (45% infected and 10 larvae per infected mosquito) than those surviving beyond 13 days (39% and 2.2), suggesting a parasite loss of more than 80% during the extrinsic incubation period. A large proportion (62%) of the mosquitoes that died during the early of phase of parasite development were infected (36% in low, 26% in medium and 90% in high human Mf-density). Survival analysis showed that the parasite load in mosquitoes and the human Mf-density for a given parasite load are independent risk factors of vector survival. Overall, the hazard of dying was found to be 11-15 times higher among mosquitoes fed on microfilaraemic volunteers than those fed on amicrofilaraemics. The hazard doubles for every increase of about 60-70 parasites in the vector. As a consequence of the parasite-induced reduction in vector survival, the transmission success of the parasite is reduced. The implication of the results on control/elimination of lymphatic filariasis using mass-drug administration is discussed.

Animals↗
PubMed2004

Role of modified CDC miniature light-traps as an alternative method for sampling adult anophelines (Diptera: Culicidae) in the National Mosquito Surveillance Programme in India.

The efficiency of modified CDC miniature light-traps for sampling adult mosquitoes was evaluated in comparison with indoor resting, outdoor resting, indoor man-landing and outdoor man-landing collections in the hilly district of Koraput, Orissa, India. Overall, light-traps captured 78% of adult mosquitoes collected by all methods. Of the 16 anopheline species recorded in the study area, light-traps effectively sampled 13, contributing about 72% of the total anophelines collected by all methods. Light-traps also caught a large number of female Culex vishnui Theobald (96%). As fully-fed mosquitoes were predominant (82%) and caught alive, light-traps can be used to catch large numbers of vector mosquitoes for studies on vector prevalence, distribution, vector incrimination and also for laboratory bioassays. Light-trap and indoor resting collections revealed similar seasonal trends in numbers of Anopheles culicifacies Giles, A. fluviatilis James, A. jeyporiensis James, A. vagus Doenitz, and A. splendidus Koidzumi. Age-structure of the samples did not vary significantly between the two methods. Light-traps could be used as an alternative to daytime indoor resting collections to monitor the seasonal fluctuations in the abundance and parity rates of these species. The light-trap collections correlated with indoor and outdoor man-landing collections of A. jeyporiensis and the outdoor man-landing collections of A. maculatusTheobald in measuring seasonal trends. Light-trap collections can thus be used as a substitute for man-landing collections of A. jeyporiensis and A. maculatus.

Animals↗
PubMed2004

Anti-diabetic activity of Eugenia jambolana seed kernels on streptozotocin-induced diabetic rats.

The present study evaluated the hypoglycemic activity of different parts of Eugenia jambolana seeds such as whole seed, kernel, and seed coat on streptozotocin-induced diabetic rats. Administration of the ethanolic extract of kernel at a concentration of 100 mg/kg of body weight significantly decreased the levels of blood glucose, blood urea, and cholesterol, increased glucose tolerance and levels of total proteins and liver glycogen, and decreased the activities of glutamate oxaloacetate transaminase and glutamate pyruvate transaminase in experimental diabetic rats. Whole seed showed a moderate hypoglycemic effect, and seed coat did not show any hypoglycemic effect. The hypoglycemic efficacy was compared with that of glibenclamide, a standard hypoglycemic drug.

Alanine Transaminase↗
PubMed2004

Hypoglycemic effect of Aloe vera gel on streptozotocin-induced diabetes in experimental rats.

In the present study an attempt has been made to evaluate the presence of hypoglycemic activity in the alcoholic extract of Aloe vera gel. Effects of oral administration of A. vera extract at a concentration of 200 and 300 mg/kg of body weight on (a) normal fasted rats, (b) oral glucose-loaded rats, and (c) streptozotocin-induced diabetic rats have been studied. A. vera extract maintain the glucose homeostasis by controlling the carbohydrate metabolizing enzymes.

Administration, Oral↗
PubMed2004

Assessing density dependence in the transmission of lymphatic filariasis: uptake and development of Wuchereria bancrofti microfilariae in the vector mosquitoes.

Understanding density dependence in the transmission of lymphatic filariasis is essential for assessing the prospects of elimination. This study seeks to quantify the relationship between microfilaria (Mf) density in human blood and the number of third stage (L3) larvae developing in the mosquito vectors Aedes polynesiensis Marks and Culex quinquefasciatus Say (Diptera: Culicidae) after blood-feeding. Two types of curves are fitted to previously published data. Fitting a linearized power curve through the data allows for correction for measurement error in human Mf counts. Ignoring measurement error leads to overestimation of the strength of density dependence; the degree of overestimation depends on the accuracy of measurement of Mf density. For use in mathematical models of transmission of lymphatic filariasis, a hyperbolic saturating function is preferable. This curve explicitly estimates the Mf uptake and development at lowest Mf densities and the average maximum number of L3 that can develop in mosquitoes. This maximum was estimated at 23 and 4 for Ae. polynesiensis and Cx. quinquefasciatus, respectively.

Aedes↗
PubMed2004

Urocortin III, a brain neuropeptide of the corticotropin-releasing hormone family: modulation by stress and attenuation of some anxiety-like behaviours.

Following its discovery 20 years ago, corticotropin-releasing hormone (CRH) has been postulated to mediate both hormonal and behavioural responses to stressors. Here, we characterize and describe a behavioural role for the murine gene, UcnIII, which encodes a recently discovered CRH-related neuropeptide, urocortin III. We found that mouse UcnIII is expressed predominantly in regions of the brain known to be involved in stress-related behaviours, and its expression in the hypothalamus increases following restraint. In addition, we found that intracerebroventricular administration of mUcnIII stimulates behaviours that are associated with reduced anxiety, including exploration of an open field and decreased latency to enter the lit compartment of a dark-light chamber, but has no effect on the elevated-plus maze. Finally, we found that mUcnIII does not exert any effects on the hormonal stress response. Based upon our findings, UcnIII may be an endogenous brain neuropeptide that is modulated by stress and stimulates behaviours associated with reduced anxiety. In this capacity, UcnIII may attenuate stress-related behaviours, which may be useful both to help cope with stressful situations as well as to avoid pathology associated with excessive reaction to stressors.

Amygdala↗
PubMed2004

Hypoglycemic activity of inorganic constituents in Eugenia jambolana seed on streptozotocin-induced diabetes in rats.

Medicinal herbs used in indigenous medicines for the management of diabetes mellitus contain both organic and inorganic constituents. Some of these inorganic trace elements possess antidiabetic properties, which accounts for the activity of medicinal herbs. The aim of this study was to analyze the inorganic trace elements present in Eugenia jambolana seeds and to evaluate the hypoglycemic activity of the inorganic part of E. jambolana seeds on streptozotocin-induced diabetes. The seeds of E. jambolana seeds were reduced to ash and the inorganic elements present were assayed. The hypoglycemic efficacy of the inorganic part was tested by the glucose tolerance test on streptozotocin-induced diabetes. Elements such as zinc, chromium, vanadium, potassium, and sodium, possessing hypoglycemic activity, were present in the seed. The E. jambolana seed ash-treated diabetic rats exhibited normoglycemia and better glucose tolerance. The conclusion that the inorganic constituents might play a important role in the antidiabetic nature E. jambolana seeds was reached.

Animals↗
PubMed2004

Microcanalization in the epididymis to overcome ductal obstruction caused by chronic exposure to chromium - a study in the mature bonnet monkey (Macaca radiata Geoffroy).

In order to apprehend the toxic effects of chromium, an occupational/environmental pollutant, on the epididymis, adult bonnet monkeys were exposed to chromium (VI) in their drinking water at concentrations of 100, 200 and 400 p.p.m. for a chronic period of 180 days. At the end of the experimental period, testicles and segments of epididymis from control and treated monkeys were subjected to light microscopic (resin-embedded semi-thin sections) and transmission electron microscopic analyses. Among the various changes undergone by the epididymal epithelium, the present paper describes the origin of two different kinds of microcanals, probably caused by ductal obstruction. The first type of microcanal, which appears to provide passage for spermatozoa to bypass the obstructed main duct, is comparable with the one already reported in carbendazim-treated efferent ductules of the rat. The second type of microcanal, which is novel, consisted of a lumen in the epithelium enclosed by four to five cells, which are either modified basal cells, principal cells or a hitherto unknown cell type. This novel type of microcanal is suggested to be a device to entrap the spermatozoa which reach the core of the epithelium and may be a mechanism to prevent extravasation of sperm so as to avoid an autoimmune response of spermatic granuloma formation. Thus, the present study has shown that chronic exposure to chromium (VI) through drinking water can produce pathological manifestations in the epididymal epithelium but the epididymis, being a versatile organ, is capable of overcoming such adverse situations through novel devices.

Animals↗
PubMed2004

Health and aesthetic impacts of copper corrosion on drinking water.

Traditional research has focused on the visible effects of corrosion--failures, leaks, and financial debits--and often overlooked the more hidden health and aesthetic aspects. Clearly, corrosion of copper pipe can lead to levels of copper in the drinking water that exceed health guidelines and cause bitter or metallic tasting water. Because water will continue to be conveyed to consumers worldwide through metal pipes, the water industry has to consider both the effects of water quality on corrosion and the effects of corrosion on water quality. Integrating four key factors--chemical/biological causes, economics, health and aesthetics--is critical for managing the distribution system to produce safe water that consumers will use with confidence. As technological developments improve copper pipes to minimize scaling and corrosion, it is essential to consider the health and aesthetic effects on an equal plane with chemical/biological causes and economics to produce water that is acceptable for public consumption.

Copper↗
PubMed2003

Diverticular disease of the colon--on the rise: a study of hospital admissions in England between 1989/1990 and 1999/2000.

BACKGROUND: Diverticular disease emerged as a common problem in Western countries over the course of the 20th century. AIMS: To determine the time trends in diverticular disease for hospital admissions in England between 1989/1990 and 1999/2000 and population mortality rates from 1979 to 1999. METHODS: Hospital Episode Statistics were obtained from the Department of Health and mortality data from the Office for National Statistics. RESULTS: Between 1989/1990 and 1999/2000, annual age-standardized hospital admission rates for diverticular disease increased by 16% for males (from 20.1 to 23.2 per 100,000) and 12% for females (from 28.6 to 31.9 per 100,000). Female rates were significantly higher than male rates throughout the study period. The proportions of admissions with an operation increased by 16% for males (from 22.9% to 24.1%) and 14% for females (from 19.7% to 22.3%). Older patients were less likely to undergo operation than younger patients. In-patient case fatality rates and population mortality rates remained unchanged. CONCLUSIONS: Admission rates for diverticular disease increased over the study period. The proportion of patients who underwent operation increased, but in-patient and population mortality rates remained unchanged. With an ageing population, diverticular disease will become an increasingly important clinical problem in England.

Adult↗
PubMed2003

Impact of alphacypermethrin treated bed nets on malaria in villages of Malkangiri district, Orissa, India.

The impact of use of bed-nets treated with alphacypermethrin, at 20 mg (ai)/m2, in comparison to untreated nets or no nets on malaria vectors and malaria incidence was studied in tribal villages of Malkangiri district, Orissa state, India, which are highly endemic for falciparum malaria. Treated or untreated nets were supplied to the villagers in June 1999 and the nets were re-treated in September 1999, just before the rise in vector abundance and malaria incidence. The seasonal pattern of indoor resting Anopheles fluviatilis females was similar in all the three groups of villages before the start of intervention and the indoor resting catches were not significantly different between treatment-groups (two-way ANOVA, F = 1.53; d.f. = (2, 78); P = 0.2). During intervention, the indoor resting catches differed significantly among treatment groups (two-way ANOVA, F = 38.9; d.f.= (2, 66); P < 0.005). There was a 99% reduction in the indoor resting catches of An. fluviatilis in villages with treated nets and 61% reduction in villages with untreated nets compared with no-net villages. Comparison between villages with and without treated nets showed that there was 97% reduction in indoor resting catches in villages with treated nets. Pair-wise comparison showed that the reductions between villages with and without nets as well as between villages with treated and untreated nets were significant (Dunnett's C-test, P < 0.05). The indoor resting catches of Anopheles culicifacies did not differ significantly among the three groups of villages either before (F = 0.99; d.f. = (2, 121); P = 0.4) or during intervention (F = 0.21; d.f. = (2, 66); P = 0.8). Bioassay with 3 min exposure to treated bed nets showed 100% mortality of An. culicifacies for 2 months and with An. fluviatilis for 4.5 months after which tests were not carried out. In villages with treated nets, the Annual Parasite Incidence (API) significantly declined (P < 0.05) by about 65.7% and prevalence of infection among children (< 15 years) declined by 57.1%, whereas in villages with untreated nets, there was only 34% reduction in API and 13% in the prevalence of infection. In villages with treated nets, there was 48% reduction in API and 64% in prevalence of infection compared with villages with untreated nets. The impact of use of treated bed nets on other arthropod pests lasted for at least 1.5 months. After 1.5 months, observations on arthropod pests were not continued. The use rate of treated nets varied from 49.8 to 93.7% in three seasons and about 68.3% of treated bed nets and 60% of untreated nets were in good condition 1 year after distribution. Out of 489 users of treated net, five people complained of a burning sensation on the face (skin irritation) for 5 days following the distribution of treated nets. There were no other complaints of any discomfort in using the treated nets. The use of alphacypermethrin treated bed nets at 20 mg (ai)/m2 can be one of the options for reducing the vector abundance and incidence of malaria in this area.

Animals↗
PubMed2003

Insulin mimetic effects of macrocyclic binuclear oxovanadium complexes on streptozotocin-induced experimental diabetes in rats.

AIM: The vanadium complexes so far tested for their insulin mimetic effects are either mono- or binuclear and contain only acyclic ligands. The leaching or hydrolysis of vanadyl ions from these complexes is much easier, and hence they elicit side effects. In the present study, a new binuclear macrocyclic oxovanadium complex was synthesized, and its efficacy was studied on streptozotocin (STZ)-induced diabetic rats over a period of 30 days. METHODS: The insulin mimetic effect of the complex was tested on the blood sugar level in the STZ-diabetic rats and on the activities of the carbohydrate-metabolizing enzymes present in the liver. RESULTS: Administration of vanadium complex to STZ-induced diabetic rats decreased blood glucose levels from hyperglycaemic to normoglycaemic when compared to diabetic rats. The activity of carbohydrate-metabolizing enzymes such as hexokinase, glucose-6-phosphate dehydrogenase, glycogen synthase and glycogen content were increased to near normal in vanadium complex-administered diabetic rats. The biochemical studies such as assay of blood urea and glutamate oxaloacetate transaminases revealed that the complex is not toxic to the system. CONCLUSION: The nontoxic nature of this complex may be due to the presence of the vanadyl ions in an intact macrocyclic form. Further, the vanadyl ions present in the macrocyclic binuclear oxovanadium complex are very close to each other, and this may enhance the insulin mimetic activity by synergic effect.

Animals↗