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Biomedical subjects

S Sarkar

Publications and source records attributed to S Sarkar.

At least 19 recordsLinked to original sources
PubMed2006

Can neutrophil responses in very low birth weight infants predict the organisms responsible for late-onset bacterial or fungal sepsis?

OBJECTIVE: To examine neutrophil counts and various neutrophil indices in preterm very low birth weight (VLBW) newborn infants (birth weight <1500 g) with culture-proven late-onset sepsis to determine whether the neutrophil responses could predict the responsible infectious agent. STUDY DESIGN: Neutrophil parameters were examined during episodes of culture-proven sepsis in a cohort of 1026 VLBW infants, born over a 6-year period and admitted to two different neonatal intensive care units. Revised reference ranges of Mouzinho et al. for circulating neutrophil counts in VLBW infants were used to define the abnormal neutrophil indices. RESULTS: One hundred sixty-two of 1026 (15.8%) VLBW infants had blood culture-proven late-onset infection. Infections included Gram-positive bacteria (113/162, 70%), Gram-negative bacteria (30/162, 18%) and fungi (19/162, 12%). Of the 162 sepsis episodes, only nine (5.5%) were associated with neutropenia (absolute total neutrophil (ATN) <1100/mm3). Six of the 30 (20%) infants with Gram-negative bacterial sepsis were neutropenic compared to 2.6% infants with Gram-positive bacterial sepsis and none with fungal sepsis (odds ratio: 11; 95% confidence interval: 2.6, 47.3). Neutrophil counts and various neutrophil indices were similar in infants with late-onset Gram-positive bacterial and fungal sepsis; but total white blood cells, and ATN count were significantly lower (P = 0.004 and 0.001, respectively) in infants with late-onset Gram-negative bacterial sepsis. CONCLUSIONS: In VLBW infants, common organisms causing infection have different effects on neutrophil responses. Occurrence of neutropenia during evaluation of sepsis in sick VLBW infants is more common with Gram-negative bacterial infection.

Diagnosis, Differential↗
PubMed2006

The mechanical properties of infrainguinal vascular bypass grafts: their role in influencing patency.

When autologous vein is unavailable, prosthetic graft materials, particularly expanded polytetrafluoroethylene are used for peripheral arterial revascularisation. Poor long term patency of prosthetic materials is due to distal anastomotic intimal hyperplasia. Intimal hyperplasia is directly linked to shear stress abnormalities at the vessel wall. Compliance and calibre mismatch between native vessel and graft, as well as anastomotic line stress concentration contribute towards unnatural wall shear stress. High porosity reduces graft compliance by causing fibrovascular infiltration, whereas low porosity discourages the development of an endothelial lining and hence effective antithrombogenicity. Therefore, consideration of mechanical properties is necessary in graft development. Current research into synthetic vascular grafts concentrates on simulating the mechanical properties of native arteries and tissue engineering aims to construct a new biological arterial conduit.

Anastomosis, Surgical↗
PubMed2006

Perceptual wind-up in the human oesophagus is enhanced by central sensitisation.

BACKGROUND: Oesophageal acid infusion induces enhanced pain hypersensitivity in non-acid exposed upper oesophagus (secondary hyperalgesia) in patients with non-cardiac chest pain, thus suggesting central sensitisation contributes to visceral pain hypersensitivity in functional gut disorders (FGD). Perceptual wind-up (increased pain perception to constant intensity sensory stimuli at frequencies>or=0.3 Hz) is used as a proxy for central sensitisation to investigate pain syndromes where pain hypersensitivity is important (for example, fibromyalgia). AIMS: Wind-up in central sensitisation induced human visceral pain hypersensitivity has not been explored. We hypothesised that if wind-up is a proxy for central sensitisation induced human visceral pain hypersensitivity, then oesophageal wind-up should be enhanced by secondary hyperalgesia. METHODS: In eight healthy volunteers (seven males; mean age 32 years), perception at pain threshold to a train of 20 electrical stimuli applied to the hand and upper oesophagus (UO) at either 0.1 Hz (control) or 2 Hz was determined before and one hour after a 30 minute lower oesophageal acid infusion. RESULTS: Wind-up occurred only with the 2 Hz train in the UO and hand (both p=0.01). Following acid infusion, pain threshold decreased (17 (4)%; p=0.01) in the UO, suggesting the presence of secondary hyperalgesia. Wind-up to the 2 Hz train increased in the UO (wind-up ratio 1.4 (0.1) to 1.6 (0.1); p=0.03) but not in the hand (wind-up ratio 1.3 (0.1) and 1.3 (0.1); p=0.3) CONCLUSION: Enhanced wind-up after secondary oesophageal hyperalgesia suggests that visceral pain hypersensitivity induced by central sensitisation results from increased central neuronal excitability. Wind-up may offer new opportunities to investigate the contribution of central neuronal changes to symptoms in FGD.

Adult↗
PubMed2006

A study of the role of multiple site blood cultures in the evaluation of neonatal sepsis.

BACKGROUND: The optimal number of blood cultures needed to document sepsis in an ill neonate has undergone little critical evaluation. Multiple site cultures may improve pathogen detection if intermittent bacteremia occurs, or if a low density of bacteria is present in the blood. We hypothesized, however, that bacterial clearance is slower and bacteremia more continuous in septic neonates, so that a single site blood culture should be sufficient to accurately document true septicemia. OBJECTIVE: To determine the need for multiple site blood cultures in the evaluation of neonates for sepsis. DESIGN/METHODS: Clinical data were prospectively collected for 216 neonates who had 269 pairs of blood cultures taken from two different peripheral sites for the evaluation of possible sepsis. A minimum of 1 ml of blood was obtained from the two peripheral sites within 15-30 min of each other. Based on prior retrospective data, we determined that 203 infants would need to have two site blood cultures to demonstrate a significant improvement in pathogen detection at an alpha of 0.05 and a beta of 0.20 (80%) power. RESULTS: A total of 186 culture pairs were taken for evaluation of early-onset sepsis in 186 neonates, while 83 pairs were drawn for evaluation of late-onset sepsis in 43 neonates. In all, 21 neonates from the late-onset group were evaluated more than once, and 12 neonates were evaluated for both early- and late-onset sepsis. In all, 20 (9.2%) of 216 neonates had 22 episodes of culture-proven sepsis at a median age of 18 days. All neonates with positive cultures had the same organism with a similar sensitivity pattern obtained from the two different peripheral sites. The other 196 study neonates had negative blood cultures from both sites. The single episode of early-onset sepsis was caused by Listeria monocytogenes, while all remaining episodes were late-onset with the following organisms: Staphylococcus epidermidis (7), methicillin-resistant Staphylococcus aureus (MRSA) (3), combined MRSA and Candida albicans (2), Candida albicans alone (2), late-onset Group B beta-hemolytic Streptococcus (GBS) (2), Klebsiella pneumoniae (2), Enterococcus fecalis (1), Escherichia coli (1), and Serratia marcescens (1). Since no infant grew organisms from only one of the two sites, the data indicate that the diagnosis of sepsis would have been made correctly in all infants with a single site culture. CONCLUSIONS: Two site blood cultures for the initial evaluation of neonatal sepsis do not have a better yield in pathogen detection. Sepsis in neonates can be detected with no loss of accuracy with a single site blood culture with blood volume of>or=1 ml.

Bacteremia↗
PubMed2006

Management of neonatal abstinence syndrome in neonatal intensive care units: a national survey.

AIMS: To determine the monitoring and treatment of neonatal abstinence syndrome (NAS) in neonatal intensive care units (NICUs) following opiate or polydrug exposure in utero. METHODS: A pretested questionnaire was distributed via email to the chiefs of the neonatology divisions with accredited Fellowship programs in Neonatal-Perinatal Medicine in the United States. RESULTS: Of the 102 individuals contacted, 75 participated in the survey. In all, 41 of the respondents (54.5%) have a written policy regarding the management of neonatal NAS. The method of Finnegan is the most commonly used abstinence scoring system (49 of 75, 65%), while only three respondents use the Lipsitz tool. Opioids (tincture of opium, or morphine sulfate solution) are used most commonly for management of both opioid (63% of respondents) and polydrug (52% of respondents) withdrawal, followed by phenobarbital (32 % of respondents) for polydrug withdrawal and methadone (20% of respondents) for opioid withdrawal. In all, 53 respondents (70%) use phenobarbital, and 19 (25%) use intravenous morphine to control opioid withdrawal seizures, while 61 (81%) use phenobarbital in cases of polydrug withdrawal seizures. Only 53 respondents (70%) always use an abstinence scoring system to determine when to start, titrate, or terminate pharmacologic treatment of neonatal NAS. CONCLUSION: The management of neonatal psychomotor behavior consistent with withdrawal varies widely, with inconsistent policies to determine its presence or treatment. Only about half of NICUs have written guidelines for the management of NAS, which may preclude effective auditing of this practice. Educational interventions may be necessary to ensure changes in clinical practice.

Humans↗
PubMed2006

Are newborns receiving premedication before elective intubation?

AIMS: To determine the extent and type of premedication used for elective endotracheal intubation in neonatal intensive care units (NICUs). METHODS: A pretested questionnaire was distributed via e-mail to the program directors of the neonatology divisions with accredited fellowship programs in Neonatal-Perinatal Medicine in the United States. RESULTS: Of the 100 individuals contacted, 78 (78%) participated in the survey. Only 34 of the 78 respondents (43.6%) always use any premedication for elective intubation. Nineteen respondents (24.4%) reported to have a written policy regarding premedication. Morphine or fentanyl was used most commonly (57.1%), with a combination of opioids and midazolam or other benzodiazepines used less frequently. Fourteen respondents (25%) also use muscle relaxants with sedation for premedication, but only nine respondents combined paralysis with atropine and sedation. CONCLUSION: Most neonatology fellowship program directors do not report always using premedication for newborns before elective endotracheal intubation despite strong evidence of physiologic and practical benefits. Only a minority of the NICUs has written guidelines for sedation, which may preclude effective auditing of this practice. Educational interventions may be necessary to ensure changes in clinical practice.

Analgesics, Opioid↗
PubMed2006

Aflatoxin B(1) contamination of parboiled rice samples collected from different states of India: A multi-centre study.

Under a multi-centre study conducted by the Indian Council of Medical Research, 1,511 samples of parboiled rice were collected from rural and urban areas of 11 states representing different geographical regions of India. These samples were analysed for contamination with aflatoxin B(1.) The presence of aflatoxin B(1) at levels=5 microg g(-1) was found in 38.5% of the total number of samples of the parboiled rice. About 17% of the total samples showed the presence of aflatoxin B(1) above the Indian regulatory limit of 30 microg kg(-1). No statistically significant difference in percentage of samples contaminated with >30 microg kg(-1) was observed between pooled rural (19.4%) and urban (14.5%) data. A median value of 15 microg kg(-1) of aflatoxin B(1) was observed in samples from Assam, Bihar and Tripura. In all other states surveyed the median value was <5 microg?kg(-1).

Aflatoxin B1↗
PubMed2006

Clients of sex workers in different regions of the world: hard to count.

OBJECTIVES: To estimate the proportion of the male population that reports having paid for sex in different regions. METHODS: Clients of sex workers were identified from representative samples of men asked in face-to-face interviews whether they had had sex in exchange for money or whether they had paid for sex, in the last 12 months. A total of 78 national household surveys and nine city based surveys were selected for inclusion. Where such surveys were not available, results of behavioural surveillance surveys and of research studies were also used. Using national estimates, a median percentage of men who reported paying for sex was calculated for each region. RESULTS: The median percentage of men who exchanged sex for money in the last 12 months in all regions was around 9-10%, with estimates from 13% to 15% in Central African region, 10 to 11% in Eastern and southern Africa, and 5-7% in Asia and Latin America. Estimates for men who paid sex were much lower at around 2-3% with ranges from 7% in the South African region to 1% in Asia and West Africa. CONCLUSIONS: Although errors of measurement and critical issues of definitions and interpretation exist, this compilation represents a first attempt to obtain reasonably coherent estimates of the proportion of men who were clients of sex workers at regional level. Large discrepancies between regions were found. Further improvements in national estimates will be critical to monitor coverage of HIV prevention programmes for sex workers and clients, and to improve estimates of national HIV infection prevalence levels in low and concentrated HIV epidemics.

Adolescent↗
PubMed2006

Study of trace elements in mixed saliva of caries free and caries active children.

The present study was carried out to find out the amount of cariogenic and cariostatic trace elements in mixed saliva. It was observed that Cu, Pb, Na showed significant variation in case of one surface as compared to caries free group. Between the non-caries and multiple caries group Cu, Pb, K showed no significant variation Zn showed highly significant variation.

Child↗
PubMed2006

Cervical screening during pregnancy.

UNLABELLED: A retrospective study done to assess the efficiency of cervical screening in the form of smear testing in pregnant population. We selected one hundred women who had undergone cervical screening during booking visit in one particular unit. Results of tests along with datas regarding age, parity and previous smear history was compiled. Results were compared with Western Health Board figures. 58% smears were normal, 6 % abnormal and 36% unsatisfactory. Although incidence unsatisfactory smears were very high, but incidence of abnormal cytology matched with standard. CONCLUSION: Pregnant women are no more likely than the general population to have a frankly abnormal smear. Despite its limitations we recommend antenatal screening does have a role in the absence of National Cervical Screening Programme.

Adult↗
PubMed2005

Segment-specific resistivity improves body fluid volume estimates from bioimpedance spectroscopy in hemodialysis patients.

Discrepancies in body fluid estimates between segmental bioimpedance spectroscopy (SBIS) and gold-standard methods may be due to the use of a uniform value of tissue resistivity to compute extracellular fluid volume (ECV) and intracellular fluid volume (ICV). Discrepancies may also arise from the exclusion of fluid volumes of hands, feet, neck, and head from measurements due to electrode positions. The aim of this study was to define the specific resistivity of various body segments and to use those values for computation of ECV and ICV along with a correction for unmeasured fluid volumes. Twenty-nine maintenance hemodialysis patients (16 men) underwent body composition analysis including whole body MRI, whole body potassium (40K) content, deuterium, and sodium bromide dilution, and segmental and wrist-to-ankle bioimpedance spectroscopy, all performed on the same day before a hemodialysis. Segment-specific resistivity was determined from segmental fat-free mass (FFM; by MRI), hydration status of FFM (by deuterium and sodium bromide), tissue resistance (by SBIS), and segment length. Segmental FFM was higher and extracellular hydration of FFM was lower in men compared with women. Segment-specific resistivity values for arm, trunk, and leg all differed from the uniform resistivity used in traditional SBIS algorithms. Estimates for whole body ECV, ICV, and total body water from SBIS using segmental instead of uniform resistivity values and after adjustment for unmeasured fluid volumes of the body did not differ significantly from gold-standard measures. The uniform tissue resistivity values used in traditional SBIS algorithms result in underestimation of ECV, ICV, and total body water. Use of segmental resistivity values combined with adjustment for body volumes that are neglected by traditional SBIS technique significantly improves estimations of body fluid volume in hemodialysis patients.

Algorithms↗
PubMed2005

Infrared optical properties and AFM of spin-cast chitosan films chemically modified with 1,2 Epoxy-3-phenoxy-propane.

Chemical modification of spin-cast chitosan films has been performed. This modification involves the attachment of 1,2 Epoxy-3-phenoxy-propane, commonly known as glycidyl phenyl ether (GPE), to the amine group of the chitosan molecule. Optical properties of modified films have been determined in the infrared region of the spectrum using spectroscopic ellipsometry, and are reported in this paper. Special attention is paid to the infrared region where the index of refraction and extinction coefficients from 750 to 4000 cm(-1) were determined. Difference plots of IR optical data before and after chemical modification were generated to confirm that modification had occurred. Optical modeling of infrared spectroscopic ellipsometry (IRSE) data with respect to chemical bond vibrations has also been performed. This modeling involved curve fitting of resonant chemical bond absorptions using Lorentz oscillators. These oscillator models allow for comparison of modified chitosan to unmodified chitosan. The purpose of this research was to determine infrared optical constants of chemically modified chitosan films This work shows that surface chemistry of biomaterials can be studied quite sensitively with spectroscopy ellipsometry, detecting as little as 100 ng/cm(2) of GPE.

Adsorption↗
PubMed2005

Interaction of arsenic with zinc and organics in a rice (Oryza sativa L.)--cultivated field in India.

A laboratory experiment on an Inceptisol with pH 7.6, organic carbon 6.8 g kg(-1), and 0.5 M NaHCO3 extractable arsenic 0.4 mg kg(-1) was conducted to study the interaction effect of graded levels of arsenic (0, 5, and 10 mg kg(-1)) with zinc (0, 10, and 20 mg kg(-1)) and organics (0, 1, and 2% on soil weight basis) separately on the mobilization of arsenic in soils. The results show that the amount of 0.5 M NaHCO3 extractable arsenic at pH 8.5 increased with the progress of submergence up to 35 days. However, the increase in arsenic concentration was correlated with decreasing application of graded levels of Zn as zinc sulfate. The intensity of reduction varied with varying levels of Zn, being higher (0.73-2.72 mg kg(-1)) in the treatment where Zn was at 10 mg kg(-1) and lower (0.70-1.08 mg kg(-1)) with Zn at 20 mg kg(-1) application. The amount of arsenic content in the soil significantly decreased with the application of varying levels of organics. However, such depressive effect was found more pronounced with well-decomposed farm yard manure than that of vermicompost. The results of field experiments showed that the grain yield between continuous flooding (4.84 t ha(-1)) and intermittent flooding up to 40 days after transplanting then continuous flooding (4.83 t ha(-1)) with the application of ZnSO4 at 25 kg ha(-1) did not vary. The lowest grain yield (3.65 t ha(-1)) was recorded in the treatment where intermittent flooding was maintained throughout the growth period without the application of Zn. The amount of arsenic content was, however, recorded much lower in the treatment where intermittent flooding throughout the growth period was maintained with ZnSO4.

Agriculture↗
PubMed2005

A possible mechanism of zero-crossing detection using the concept of the extended classical receptive field of retinal ganglion cells.

The extended classical receptive field (ECRF) of retinal ganglion cells has been modelled as a combination of three zero-mean Gaussians at three different scales that has been shown to be equivalent to a Biharmonic or Bi-Laplacian of Gaussian filter. It has also been shown that the ECRF can be approximated by a combination of Laplacian of Gaussian (LoG) and the Dirac-delta function. Zero-crossings detected with this operator are more informative than those detected by the traditional filters like LoG or Difference of Gaussians (DoG) that had been devised using the classical receptive field of the ganglion cells. We have also explained that such an additional information processing is not in contradiction with the recent experimental findings on the physiology of retinal ganglion cells.

Animals↗
PubMed2005

UV-vis-infrared optical and AFM study of spin-cast chitosan films.

Optical properties of spin-cast chitosan films have been determined in the infrared, visible, and ultraviolet region of the spectrum using spectroscopic ellipsometry. Optical constants for the UV-vis-near IR spectra from 130 to 1700 nm were determined using Cauchy dispersion forms combined with Lorentzian oscillator models in the absorptive shorter wavelength regions. Infrared index of refraction and extinction coefficients from 750 to 4000 cm(-1) were determined using ellipsometric data fits to dispersion models based on harmonic oscillators. This modeling determined that optical anisotropy was present and measurable over all wavelength regions of ellipsometric data. To obtain information on the micro- and nano-scale surface structure, tapping mode atomic force microscopy (AFM) imaging was employed to determine morphology and roughness information of dry spin-cast chitosan films.

Algorithms↗
PubMed2005

Structural changes of DNA induced by mono- and binuclear cancer drugs.

The structural features of the drug-DNA adducts resulted from treatment of DNA with the platinum based mononuclear drug cisplatin and the binuclear drug [{trans-PtCl(NH3)2}2H2N(CH2)4NH2]Cl2 or bis(platin) have been investigated by atomic force microscopy (AFM). Reduction in the contour length of the DNA fragments has been observed after cisplatin treatment while, compaction and aggregation are found to be the primary structural modifications following treatment with the binuclear drug. The intermolecular interaction upon bis(platin) treatment leads to observation of highly condense aggregates without a distinct sight of single isolated DNA molecule. These differences in drug binding indicate that unlike the mononuclear drug cisplatin, bis(platin) causes extensive interhelical/intermolecular cross-linking through its multiple linking sites. To our knowledge, this is the first report of a comparative AFM study to monitor the effects of a mono- and a binuclear platinum anti-cancer drug on DNA structure. These observations should provide clues towards explaining the distinct biological activities of the two drugs.

Aluminum Silicates↗