PubMed Health⌕ Search

Biomedical subjects

R Sinha

Publications and source records attributed to R Sinha.

At least 19 recordsLinked to original sources
PubMed1995

High concentrations of the carcinogen 2-amino-1-methyl-6-phenylimidazo- [4,5-b]pyridine (PhIP) occur in chicken but are dependent on the cooking method.

Heterocyclic aromatic amines (HAAs) are mutagenic and carcinogenic compounds found in meats cooked at high temperatures. Although chicken is consumed in large quantities in the United States, there is little information on its HAA content. The objective of this study was to measure the five predominant HAAs (IQ, MeIQ, MeIQx, DiMeIQx, and PhIP) in chicken cooked by various methods to different degrees of doneness. Chicken breasts were panfried, oven-broiled, or grilled/barbecued. Whole chickens were roasted or stewed. Skinless, boneless chicken breasts were cooked to three degrees of doneness: just until done, well done, or very well done. High levels of PhIP (ranging from 12 to 480 ng/g cooked meat) were found in chicken breasts when panfried, oven-broiled, and grilled/barbecued but not in while roasted or stewed chicken. PhIP concentration increased in skinless, boneless chicken breast with longer cooking time, higher internal temperature, and greater degree of surface browning. PhIP concentration was also high in chicken breasts cooked with skin and bones. MeIQx and DiMeIQx levels increased with the degree of doneness, whereas IQ and MeIQ were not detectable in any of these chicken samples. Certain cooking methods produce PhIP, a known colon and breast carcinogen in rodents and possibly a human carcinogen, at substantially higher levels in chicken than has been reported previously in red meat.

Animals↗
PubMed1995

Effects of ethanol on the processing of low probability stimuli: an ERP study.

The effect of a moderate dose of ethanol on the processing of low probability task-relevant and task-irrelevant stimuli was investigated using event-related potentials (ERPs). Sixteen subjects received alcoholic and placebo beverages on alternate days. ERPs were recorded from 15 locations on the scalp. The subjects were asked to press a button upon detection of rare target stimuli embedded among frequent standard and rare "novel" stimuli. Ethanol 1) reduced the amplitude of P3 to novel stimuli, but not P3 to target stimuli, 2) did not affect the mismatch negativity, and 3) delayed P3 latency and reaction time independently. These results suggest that 1) the processing of rare task-irrelevant stimuli is more vulnerable to the effects of ethanol than is the processing of task-relevant stimuli, and 2) ethanol impacts stimulus evaluation time and response production stages of information processing.

Acoustic Stimulation↗
PubMed1995

Transvaginal endoscopic oophorectomy.

Four women underwent transvaginal endoscopic oophorectomy during vaginal hysterectomy. The adnexa were visualized with a laparoscope inserted into the upper vagina. Bilateral salpingo-oophorectomy or oophorectomy was carried out with standard laparoscopic instruments introduced through the vagina without a pneumoperitoneum; Endoloop sutures and bipolar electrocoagulation were used for hemostasis.

Fallopian Tubes↗
PubMed1995

Heterocyclic amine content in fast-food meat products.

Heterocyclic aromatic amines are sometimes formed during the cooking of muscle meats, and their mutagenic and carcinogenic effects are of potential concern in the aetiology of human cancer. In a large survey of the heterocyclic amine content of foods, fried or charbroiled hamburgers, fried chicken, chicken breast sandwiches, fish sandwiches and breakfast sausages were purchased from fast-food restaurants. At least three different chains were visited per product and samples from five stores from each chain were pooled. The solid-phase extraction and HPLC method was used to analyse pooled samples for heterocyclic amine content and mutagenic activity with the Ames/Salmonella assay. Samples were analysed in a blind study which also contained quality control samples of two types, one high and one low in heterocyclic amine content and mutagenic activity. Results from the fast-food products showed undetectable levels of heterocyclic amines in 10 of 17 samples and only low levels [< or = 1 ng/g total of 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx), 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) and 2-amino-3,4,8-trimethylimidazo[4,5-f]quinoxaline (DiMeIQx)] in the remaining samples. Compared with literature values based primarily on laboratory and home cooking conditions, fast-food meat products appear to contribute only a small percentage of the estimated daily dietary intake of heterocyclic amines.

Amines↗
PubMed1995

Lower levels of urinary 2-amino-3,8-dimethylimidazo[4,5-f]-quinoxaline (MeIQx) in humans with higher CYP1A2 activity.

Heterocyclic aromatics amines (HAAs), such as 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx), are metabolically activated by cytochrome P4501A2 (CYP1A2) and N-acetyltransferase (NAT2). We examined the relationship between CYP1A2 and NAT2 activity and the excretion of total unconjugated MeIQx in 66 healthy subjects. The subjects ate a control diet for 7 days containing lean ground beef cooked at low temperature. On day 8, they were tested for CYP1A2 and NAT2 activity by caffeine phenotyping. On the evening of day 8, subjects consumed lean ground beef cooked at high temperature containing 9.0 ng of MeIQx/g of meat. The subjects ate 3.1-4.0 g meat/kg body wt. Twelve-hour urine samples were collected and MeIQx was measured by gas chromatography-mass spectrometry. Using linear regression analyses, we found that higher CYP1A2 activity was associated with lower levels of total unconjugated MeIQx in the urine (P = 0.008) when adjusted for amount of meat eaten, while NAT2 activity showed no relationship with the latter. This suggest that a greater percentage of MeIQx is converted to metabolites such as the N-hydroxy derivative when CYP1A2 activity is higher. This finding supports the concept that inter-individual variation is CYP1A2 activity may be relevant for cancers associated with exposure to HAAs.

Adult↗
PubMed1994

Pan-fried meat containing high levels of heterocyclic aromatic amines but low levels of polycyclic aromatic hydrocarbons induces cytochrome P4501A2 activity in humans.

Heterocyclic aromatic amines (HAAs) are formed when meat juices are pyrolyzed. In humans HAAs are activated in vivo by cytochrome P4501A2 (CYP1A2) and N-acetyltransferase (NAT2) to mutagens or carcinogens. While activity of NAT2 is noninducible, exposure to cigarettes, polycyclic aromatic hydrocarbons, and cruciferous vegetables has been shown to induce CYP1A2 activity in humans. To date, it is unknown if pan-fried meat, which is consumed at high levels in the United States, is capable of inducing CYP1A2. In order to address this issue, we measured CYP1A2 and NAT2 activities in 66 healthy nonsmokers (33 males and 33 females) in a controlled metabolic feeding study. The study was designed to minimize the influence of known inducers of CYP1A2. Subjects consumed meat pan-fried at a low temperature (100 degrees C) for 7 days followed by 7 days of meat pan-fried at a high temperature (250 degrees C). The low temperature-cooked meat had undetectable levels of HAAs while the high temperature-cooked meat contained high amounts of HAAs [9.0 ng/g of 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx), 2.1 ng/g of 2-amino-3,7,8-trimethylimidazo[4,5-f]quinoxaline (DiMeIQx), and 32.8 ng/g of 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP)]. In contrast, total polycyclic aromatic hydrocarbon content was similar in both meat samples (10.7 ng/g in low temperature-cooked meat and 10.1 ng/g in high temperature-cooked meat). At the end of each period, subjects were tested for CYP1A2 and NAT2 enzyme activity by caffeine metabolism phenotyping. NAT2 activity remained unchanged throughout the study while CYP1A2 activity increased in 47 of 65 (72%) of the subjects after consuming high temperature-cooked meat (P < 0.0002), suggesting induction by some compound(s) formed during high temperature cooking. If HAAs are shown to be human carcinogens in epidemiological studies, then meat cooked at high temperatures may pose an increased cancer risk because it contains both inducers of CYP1A2 and procarcinogens MeIQx, DiMeIQx, and PhIP known to be activated by this enzyme.

Carcinogens↗
PubMed1994

Assessment of recovery of electrophysiological and neuropsychological functions in chronic alcoholics.

Potential recovery of electrophysiological and neuropsychological functions was investigated in alcoholics completing treatment and controls. Event-related potentials (ERPs) and neuropsychological tests were administered initially and repeated 14 months later. Alcoholics were classified as resumers or abstainers based on consumption patterns before retest. Resumers (n = 28), abstainers (n = 44), and controls (n = 44) differed significantly on ERP measures. No test-retest or group x test-retest interactions were found, indicating little recovery or change in ERPs over time. Differences between groups could not be attributed to family history factors. For neuropsychological efficiency (Accuracy/Time) measures, significant group differences were found. All groups improved from test to retest, with resumers showing the greatest improvement. Analysis of the separate efficiency components indicated resumers' improvement was due to a decrease in performance time, whereas accuracy scores remained significantly impaired. Whether the continued deficits in ERPs and neuropsychological performance at retest is a permanent effect of alcohol abuse, or would remit over longer periods of time, or reflects premorbid deficits, remains to be investigated.

Adult↗
PubMed1994

Effects of ethanol on the acoustic startle reflex in humans.

The effect of ethanol on human sensorimotor reactivity was assessed by examining the acoustic startle response. Twelve healthy normal subjects participated in a startle reflex experiment in which placebo or ethanol were given on separate days. Three types of startle probes were used. They consisted of pulse-alone bursts of white noise at 108 dB(A) and 99 dB(A) to explore startle reactivity, and of a 108 dB(A) pulse preceded by a 85 dB(A) prepulse stimulus (prepulse+pulse) to assess prepulse inhibition. Startle amplitude was larger to the 108 dB(A), compared to the 99 dB(A) pulse-alone probes. The prepulse stimulus significantly reduced the amplitude of the startle reflex elicited by the subsequent 108 dB(A) stimulus. The amplitude of the startle response was dramatically reduced by acute ethanol. The effects of ethanol on prepulse inhibition could not be assessed because the startle response was too small in the ethanol condition.

Acoustic Stimulation↗
PubMed1994

Importance of supplemental vitamin C in determining serum ascorbic acid in controls from a cervical cancer case-control study: implications for epidemiological studies.

Classification of individuals by their vitamin C intake was investigated in 493 control subjects from a cervical cancer case-control study. The influence of dietary and supplemental sources of vitamin C, as well as demographic and life-style factors, on serum ascorbic acid were examined. Usual dietary intakes of vitamin C were determined from a food frequency questionnaire and recent intakes from a 24-hour recall taken at the time of blood collection. Vitamin supplement information was obtained at both times. In a regression analysis, the factors found to predict serum ascorbic acid were total recent vitamin C intake, an indicator variable for supplement use, body mass index, number of cigarettes smoked per day, race, education, and age. Higher levels of serum ascorbic acid were found among older nonsmoking highly educated leaner white women. Consideration of supplements, in addition to dietary sources of vitamin C, improved correlation coefficients between serum ascorbic acid and usual vitamin C intake from 0.19 to 0.32 and between serum ascorbic acid and recent intake from 0.36 to 0.56. Furthermore, whereas only a twofold difference between the first and fourth quartiles of serum ascorbic acid was observed using recent dietary vitamin C without supplements, this range increased to sixfold with addition of supplement data. Epidemiological studies should consider use of total vitamin C intakes from supplement and food sources to permit accurate classification of individuals.

Adult↗
PubMed1994

Comparative evaluation of serological tests in Indian kala-azar.

Data on 41 kala-azar patients were collected and the series of serological tests employed to diagnose the disease were compared depending upon their sensitivity and specificity indices. The indirect fluorescent antibody test (IFAT) was found to be 100% sensitive and specific. The direct agglutination test (DAT) involving detection of agglutinating antibodies against Leishmania donovani was 97.2% efficient. The enzyme-linked immunosorbent assay (ELISA) had a specificity of 75% while other tests such as counter-immunoelectrophoresis (CIEP), aldehyde and the Sia water test ranged from 84.3 to 97.2% in efficiency. On the basis of the costs and ease of the tests, the use of DAT along with CIEP is highly recommended for early detection of kala-azar.

Agglutination Tests↗
PubMed1992

Long-term test-retest reliability of event-related potentials in normals and alcoholics.

The long-term test-retest reliability of event-related potentials (ERP) measures was examined in a group of 44 controls and 71 chronic alcoholics, retested after an average of 14 months. Correlational analyses revealed moderately significant test-retest correlations for visual and auditory target N1, N2, and P3 amplitudes, with significant correlations for N1, N2 and P3 latencies. Controls and alcoholics produced similar test-retest correlations for visual and auditory ERP measures. Men and women produced equally stable ERP measures over time. Overall N1 and P3 amplitudes were most reliable in both groups followed by N2 amplitude, N1 and N2 latency, and P3 latency. The stability of ERP measures found in this study over a 14-month period in both normals and chronic alcoholics supports the use of ERPs in the study of normal and disordered cognitive functioning.

Adult↗
PubMed1992

Humoral antibody response in Leishmania tropica infection.

A small epidemic of Leishmania tropica infection was detected in Rajasthan, India. Most cases were in the 21-25 years age group and were possibly related to outdoor activity. Nearly one third of the patients had more than five lesions, the maximum number of lesions being confined to the face, neck and extremities. As determined by ELISA, 90% cases had leishmania antibodies with an OD range of 0.8-1.1. The serum of 60% of patients was positive by CIEP against L. tropica promastigote soluble antigen. By immunofluorescence, 96% persons were positive when L. tropica promastigotes were used as the substrate. The prevalence of infection with L. tropica appears to be much higher than that reported earlier.

Adolescent↗
PubMed1992

Detection of leishmania antigen in kala azar patients using monoclonal antibodies.

Twenty-one monoclonal antibodies were produced against promastigote antigens of Leishmania donovani. Five monoclonal antibodies (Hyb.17, 6, 5, 4 and 2) identifying molecules associated with various L. donovani antigenic determinants ranging from 42-116 kDa were selected as 'capture antibodies' and compared with specific anti-leishmania antisera for detection of circulating leishmania antigens in kala azar patients' sera in a competitive-enzyme-linked immunosorbent assay system (ELISA). The anti-leishmania antisera could detect circulating antigen in 30% of kala azar cases while out of the five monoclonals, Hyb.17 could effectively detect circulating leishmania antigen in 85.4%. The efficacy of Hyb.6 was however low (31.7%). The antigens recognized by these monoclonal antibodies in the western blot assay could possibly represent the ones circulating in sera of patients suffering from kala azar. A cocktail of these monoclonal antibodies may be more useful than the conventional polyclonal antisera in detection of circulating antigen for clinical diagnosis of kala azar.

Animals↗
PubMed1991

Use of in vitro method to assess different brands of anti-leishmanial drugs.

Reports in the literature indicate the use of animal models for testing newer anti-leishmanial drugs in vivo. However, in certain established cell lines and macrophages in vitro models have the advantage over the in vivo system of simplicity and speed with which the results can be obtained. A simple in vitro system using peritoneal exudate macrophages of BALB/c mice infected with Leishmania donovani promastigotes has been tested for its use in determining the efficacy of several new drugs. Two well-established drugs, amphotericin B and sodium stibogluconate, as expected, could kill the intracellular parasites effectively. Two relatively new drugs not routinely used against leishmania, rifampicin and metronidazole at concentrations of 20 micrograms/ml and 10 micrograms/ml, respectively, were also able to kill the intracellular leishmania parasites effectively. Critical factors for drug testing in vitro have been elucidated: the most important being the temperature of incubation after infection.

Animals↗
PubMed1990

Quantification of tremor with a digitizing tablet.

Handwriting and drawing are commonly employed in the clinical assessment of tremor. These tasks have been quantified heretofore by subjective rating schemes, which are incapable of providing precise measures of the amplitude and frequency of tremor. A commercially-available digitizing tablet and personal computer can be interfaced so as to reliably record any pathologic tremor that is induced by writing or drawing. Numerical differentiation and spectral analysis can be used to conveniently quantify the amplitude and frequency of tremor. However, digitizing tablets lack sufficient sensitivity to measure physiologic tremor.

Handwriting↗
PubMed1990

Post-testicular antifertility effects of Abrus precatorius seed extract in albino rats.

Oral administration of a 50% ethanol extract of Abrus precatorius seeds (250 mg/kg) in albino rats for 30 and 60 days induced an absolute infertility in males which was reversible. Suppression of sperm motility in the cauda epididymis was the most pronounced effect of the treatment. Such treatment may affect the oxidative/energy metabolism of the cauda epididymis. Histological and histocytometric observations in testis and parareproductive tissues appeared normal while the protein, sialic acid, acid phosphatase and succinic dehydrogenase levels were significantly depleted.

Acid Phosphatase↗