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Biomedical subjects

R Roy

Publications and source records attributed to R Roy.

At least 37 records · Page 2Linked to original sources
PubMed2004

Microscale and molecular assessment of impacts of nickel, nutrients, and oxygen level on structure and function of river biofilm communities.

Studies were carried out to assess the influence of nutrients, dissolved oxygen (DO) concentration, and nickel (Ni) on river biofilm development, structure, function, and community composition. Biofilms were cultivated in rotating annular reactors with river water at a DO concentration of 0.5 or 7.5 mg liter(-1), with or without a combination of carbon, nitrogen, and phosphorus (CNP) and with or without Ni at 0.5 mg liter(-1). The effects of Ni were apparent in the elimination of cyanobacterial populations and reduced photosynthetic biomass in the biofilm. Application of lectin-binding analyses indicated changes in exopolymer abundance and a shift in the glycoconjugate makeup of the biofilms, as well as in the response to all treatments. Application of the fluorescent live-dead staining (BacLight Live-Dead staining kit; Molecular Probes, Eugene, Oreg.) indicated an increase in the ratio of live to dead cells under low-oxygen conditions. Nickel treatments had 50 to 75% fewer 'live' cells than their corresponding controls. Nickel at 0.5 mg liter(-1) corresponding to the industrial release rate concentration for nickel resulted in reductions in carbon utilization spectra relative to control and CNP treatments without nickel. In these cases, the presence of nickel eliminated the positive influence of nutrients on the biofilm. Other culture-dependent analyses (plate counts and most probable number) revealed no significant treatment effect on the biofilm communities. In the presence of CNP and at both DO levels, Ni negatively affected denitrification but had no effect on hexadecane mineralization or sulfate reduction. Analysis of total community DNA indicated abundant eubacterial 16S ribosomal DNA (rDNA), whereas Archaea were not detected. Amplification of the alkB gene indicated a positive effect of CNP and a negative effect of Ni. The nirS gene was not detected in samples treated with Ni at 0.5 mg liter(-1), indicating a negative effect on specific populations of bacteria, such as denitrifiers, resulting in a reduction in diversity. Denaturing gradient gel electrophoresis revealed that CNP had a beneficial impact on biofilm bacterial diversity at high DO concentrations, but none at low DO concentrations, and that the negative effect of Ni on diversity was similar at both DO concentrations. Notably, Ni resulted in the appearance of unique bands in 16S rDNA from Ni, DO, and CNP treatments. Sequencing results confirmed that the bands belonged to bacteria originating from freshwater and marine environments or from agricultural soils and industrial effluents. The observations indicate that significant interactions occur between Ni, oxygen, and nutrients and that Ni at 0.5 mg liter(-1) may have significant impacts on river microbial community diversity and function.

Biofilms↗
PubMed2004

Decision making and modes of death in a tertiary neonatal unit.

AIMS: To study the frequency and reason for withdrawal/withholding of life sustaining treatment (LST) and do not resuscitate (DNR) orders in infants who died in a tertiary neonatal unit. METHODS: Infants who died at Homerton University Hospital between January 1998 and September 2001 were studied by retrospective analysis of patient records. RESULTS: The case notes of 71 (84%) of 85 infants who died were studied. Mode of death was withdrawal of LST in 28 (40%), DNR in 11 (15%), withholding of LST in two (3%), and natural in 30 (42%) infants. Withdrawal of LST was discussed with the parents of 39 seriously ill infants; 28 (72%) parents agreed. There was no difference in birth weight and gestational age of babies whose parents agreed or refused withdrawal of LST. White and Afro-Caribbean parents and those from the Indian subcontinent (20 of 23) were more likely to agree to withdrawal of LST than Black African or Jewish (eight of 16, p = 0.015) parents. The median age at withdrawal of LST was 4 days (range 1-57). The median duration between discussion and the parents agreeing to withdrawal of LST was 165 minutes (range 30-2160), and median duration between withdrawal of LST and death was 22 minutes (range 5-210). The most common reason for withdrawal of LST was complications of extreme prematurity (68%). CONCLUSION: The most common mode of death was withdrawal of LST, and the most common reason was complications of extreme prematurity. The ethnic and cultural background of the parents influenced agreement to withdrawal of LST.

Age Factors↗
PubMed2003

"Amnion Bank"--the use of long term glycerol preserved amniotic membranes in the management of superficial and superficial partial thickness burns.

With about 2 million cases of burns in India of which about 90% are superficial and superficial partial thickness burns, burn injuries present a major challenge to the scarce medical resources available. The main requirement in treating these burns is an economical, easy to apply, readily available dressing that will provide good pain relief, protect the wound from infection, promote healing, prevent heat and fluid loss, be elastic and non-antigenic and adhere well to the wound. It was in the quest of such an ideal dressing that the Burn Centre of the Army Hospital (Research and Referral) New Delhi, India has been using human amniotic membranes preserved long term in 85% glycerol for treating these wounds. The results of this quest have resulted in a protocol where these long term glycerol preserved membranes (some of which have now been preserved for about 2.5 years) are used for treating superficial and superficial thickness burns presenting at our center. This paper shows the excellent results obtained with the use of this extremely economical dressing and emphasizes the importance of establishing such "Amnion Banks" in all hospitals especially in developing countries.

Amnion↗
PubMed2003

Genetic analysis of growth traits in Muzaffarnagari sheep.

Data on 4112 Muzaffarnagari sheep, maintained at the Central Institute for Research on Goats, Makhdoom, Mathura, India, and recorded between 1976 and 1999, were analysed to study the growth-related traits and their genetic control. The average weights at birth, and at 12 months of age were 3.1 +/- 0.2 and 28.0 +/- 0.6 kg, respectively. The pre- and post-weaning average daily weight gains were 127.8 +/- 3.3 g and 49.4 +/- 1.6 g. and the associated growth efficiencies were 3.59 +/- 0.08 and 0.95 +/- 0.03. Significant differences associated with the year of lambing were observed in body weight, weight gain and efficiency in weight gain at different stages of growth. The lambs born in the dam's second parity were generally of heavier weight and higher daily weight gain than those born in other parities. Males were heavier and had a higher weight gain than females at almost all stages of growth and the differences tended to increase with age. Single-born lambs had a distinct advantage over those born in multiple births at all stages of growth. The heritabilities of all body weights, weight gains and efficiency in weight gains at different stages of growth were moderate (0.18-0.26), except for birth weight, which was of low heritability (0.068 +/- 0.01). The phenotypic and genetic correlations among the different body weights were positive and high, except for birth weight. The genetic correlation of the pre- and post-weaning average daily weight gains with body weights were high and positive.

Animal Husbandry↗
PubMed2003

Genetic resistance of Barbari and Jamunapari kids to natural infection with gastrointestinal nematodes.

An investigation was made in 252 Barbari and Jamunapari kids to assess their resistance to natural infection with gastrointestinal (GI) nematodes and to establish indicator traits for such resistance in Indian goats. The indicator traits, faecal egg counts (FEC) and packed cell volume (PCV) were affected by various genetic and non-genetic factors. There were no breed differences in the FEC or PCV at 3, 6 or 9 months of age. Jamunapari male kids had a higher FEC than the female kids at 6 months of age. However, Barbari female kids had a higher FEC than the respective male kids at 9 months of age. At 6 months of age in both breeds, the kids born in the spring (March-April) had a higher FEC than those born in the autumn (October-November). The FEC of kids at 9 months of age was higher than at 3 or 6 months of age. Sire had a significant effect on PCV at 6 and 9 months of age. The kids born in the autumn had a higher PCV than those born in the spring. The PCV of male Barbari kids differed significantly from that of female kids at all the ages. The correlation coefficient of FEC on both body weight and body weight gain was negative, and there was a loss of body weight in the individuals with a high FEC.

Age Factors↗
PubMed2003

Broad identification of bacterial type from pus by 1H MR spectroscopy.

BACKGROUND: Abscess formation is a common bacterial infection and requires an immediate antimicrobial approach for apposite treatment. Delay in patient treatment is usually a common feature, as the bacterial identification of clinical samples is based on the culture, which is a time-consuming exercise. The current study was aimed at developing an alternative technique with the potential for rapid bacterial group identification. MATERIALS AND METHODS: In the present study we performed ex vivo proton magnetic resonance spectroscopy of 40 pus samples collected from abscesses in different locations and the results have been retrospectively compared with the microorganism identified in the pus culture. In addition, the microbes obtained from the culture have been further subcultured and studied with magnetic resonance spectroscopy to identify the bacterial fingerprint in the pus sample seen on spectroscopy. RESULTS: On reviewing the spectra obtained from the various abscesses, they were found to be qualitatively similar for a particular bacterium. The similar spectral pattern of the pus with obligate aerobes/anaerobes and pure cultures of the same bacteria suggests its strict metabolism under in vivo and in vitro conditions, respectively. CONCLUSIONS: The characteristic metabolite pattern of obligate anaerobes may be used as a prototype for its rapid identification. This information may be of value for more appropriate clinical management of such cases.

Abscess↗
PubMed2003

Robustness and precision of an automatic marker detection algorithm for online prostate daily targeting using a standard V-EPID.

An algorithm for the daily localization of the prostate using implanted markers and a standard video-based electronic portal imaging device (V-EPID) has been tested. Prior to planning, three gold markers were implanted in the prostate of seven patients. The clinical images were acquired with a BeamViewPlus 2.1 V-EPID for each field during the normal course radiotherapy treatment and are used off-line to determine the ability of the automatic marker detection algorithm to adequately and consistently detect the markers. Clinical images were obtained with various dose levels from ranging 2.5 to 75 MU. The algorithm is based on marker attenuation characterization in the portal image and spatial distribution. A total of 1182 clinical images were taken. The results show an average efficiency of 93% for the markers detected individually and 85% for the group of markers. This algorithm accomplishes the detection and validation in 0.20-0.40 s. When the center of mass of the group of implanted markers is used, then all displacements can be corrected to within 1.0 mm in 84% of the cases and within 1.5 mm in 97% of cases. The standard video-based EPID tested provides excellent marker detection capability even with low dose levels. The V-EPID can be used successfully with radiopaque markers and the automatic detection algorithm to track and correct the daily setup deviations due to organ motions.

Algorithms↗
PubMed2002

Cerebellar hemangioblastoma simulating arachnoid cyst on imaging and surgery.

A case of posterior fossa hemangioblastoma simulating arachnoid cyst on imaging and peroperatively is presented. In vivo proton MR spectroscopy showed evidence of large lactate and resonance at 2.37 ppm not observed earlier in the cystic lesions, including arachnoid cyst. The demonstration of this resonance may help in characterization of these lesions that may be confused with arachnoid cysts on imaging and during surgery.

Adult↗
PubMed2002

Evaluation of single- and multiple-dose pharmacokinetics of synthetic conjugated estrogens, A (Cenestin) tablets: a slow-release estrogen replacement product.

A multiple-dose, placebo-controlled, randomized pharmacokinetic study was performed in 15 early (i.e., 1-3 years) postmenopausal women to evaluate the single and steady-state pharmacokinetics of 0.625 mg Cenestin (Synthetic Conjugated Estrogens, A) tablets, administered once daily for 90 days. Plasma concentration-time profiles for both total (conjugated and unconjugated) estrone and equilin, two major estrogens in Cenestin, were nearly superimposable between Day 1 (single dose) and Day 90 (multiple dose), indicating equivalent drug exposure from one dose to the next. For total estrone, the mean estimates of Cmax and AUC0-24 were 2.5 ng/ml and 35.0 ng x h/ml for Day 1 and 3.0 ng/ml and 39.8 ng x h/ml for Day 90, respectively. Similarly, Cmax and AUC0-24 mean values for total equilin were 1.4 ng/ml and 17.4 ng x h/ml after Day 1 and 1.5 ng/ml and 17.3 ng x h/ml after Day 90, respectively. The mean tmax value for total estrone was 8.3 hours on Day 1 and 8.6 hours on Day 90, indicating a slower rate of absorption. The average estimate for observed drug accumulation index for the 24-hour dosing interval was calculated to be 1.1 for total estrone and 1.0 for total equilin. These data, taken together, indicate a slow and steady rate of absorption, minimal drug accumulation at steady state, and consistent drug exposure between Cenestin doses.

Adult↗
PubMed2001

Mutation at active site lysine 212 to arginine uncouples the glycosylase activity from the lyase activity of human endonuclease III.

The human endonuclease III (hNTH1) is an important DNA glycosylase with associated abasic lyase activity. We previously demonstrated that the K212Q mutant was totally inactive, while the K212R mutant had reduced DNA glycosylase/lyase activity and could form a covalent complex with the substrate DNA upon reduction. We further characterized the biochemical properties of this K212R mutant protein. NH2- (N-) terminal sequencing in combination with mass spectrometry of the peptide-DNA adduct suggested that "opportunistic" lysine(s) in the lysine-rich N-terminal tail formed a Schiff base which might result in beta-elimination. However, simultaneous substitution of Lys-75 with Gln and deletion of first 72 residues in the N-terminal tail could not cause further alteration in the glycosylase reaction or beta-elimination event. Nonetheless, the time kinetics of K212R and its subsequent mutants showed glycosylase activity without any detectable AP-lyase activity during the first 10 min of the reaction. These results suggest that a single point mutation at the active site (K212R) uncoupled the glycosylase activity from the lyase activity. We propose that the uncoupled reaction carried out by K212R is a result of direct attack either by the nonionized form of the guanidino group of arginine which forms an unstable Schiff base that hydrolyzes prior to the beta-elimination event or by hydroxide ion to cleave the glycosylic bond. In either case this reaction is followed by a secondary beta-elimination event performed by random lysine residues primarily from the N-terminal tail region.

Amino Acid Substitution↗
PubMed2001

Detecting phase synchronization in a chaotic laser array.

Detection of phase synchronization of coupled chaotic oscillators is examined experimentally for the case of a linear laser array. Phase variables are computed by applying a Gaussian filter, peaked at a positive frequency, to the signal obtained from the intensity time series of the individual lasers. Relationships between different frequency components of the oscillator dynamics that are not otherwise apparent are unambiguously detected.

Journal Article↗