Biomedical subjects

A Sengupta

Publications and source records attributed to A Sengupta.

At least 37 records · Page 2Linked to original sources

PubMed2001

In vitro bond strengths of resin modified glass ionomer cements and composite resin self-cure adhesives: introduction of an adhesive system with increased bond strength and inhibition of decalcification.

This study evaluated the shear bond strength and adhesive remnant index of 5 self-cure adhesives to comparatively evaluate a new adhesive system. Extracted human incisors were randomly divided into 7 test groups of 20 each. Incisor mesh-backed brackets were bonded to the tooth specimens in each group with their respective adhesive according to the manufacturer's instructions. The specimens were thermocycled for 2 weeks at temperatures from 5 degrees to 55 degrees C to simulate oral conditions and debonded using an Instron machine. Acceptable bond strength parameters were present with the Contacto No-Mix (composite resin containing glass ionomer 8.75 MPa) and Fuji Ortho SC with acid conditioning (6.98 MPa). Contacto No-Mix had a higher bond strength (11.2 MPa) when microetching and Megabond were employed than when these adjuncts were not employed. When FUJI Ortho SC specimens were conditioned with polyacrylic acid, they showed a higher bond strength (6.98 MPa) than when bonded to unetched teeth (5.41 MPa). In test 3, EXPT-fluoride adhesive (AF) demonstrated a higher bond strength (13.44 MPa) than both resin composite Contacto No-Mix (8.8 MPa, GAC 7.4 MPa) and FUJI Ortho SC (5.41 MPa). Expt AF (Test 3) and Concise had equal bond strengths, however, the former can potentially release fluoride from the glass ionomer. Although the Ex

Adhesiveness↗

PubMed2001

Functional domains of yeast plasmid-encoded Rep proteins.

Both of the Saccharomyces cerevisiae 2 microm circle-encoded Rep1 and Rep2 proteins are required for efficient distribution of the plasmid to daughter cells during cellular division. In this study two-hybrid and in vitro protein interaction assays demonstrate that the first 129 amino acids of Rep1 are sufficient for self-association and for interaction with Rep2. Deletion of the first 76 amino acids of Rep1 abolished the Rep1-Rep2 interaction but still allowed some self-association, suggesting that different but overlapping domains specify these interactions. Amino- or carboxy-terminally truncated Rep1 fusion proteins were unable to complement defective segregation of a 2 microm-based stability vector with rep1 deleted, supporting the idea of the requirement of Rep protein interaction for plasmid segregation but indicating a separate required function for the carboxy-terminal portion of Rep1. The results of in vitro baiting assays suggest that Rep2 contains two nonoverlapping domains, both of which are capable of mediating Rep2 self-association. The amino-terminal domain interacts with Rep1, while the carboxy-terminal domain was shown by Southwestern analysis to have DNA-binding activity. The overlapping Rep1 and Rep2 interaction domains in Rep1, and the ability of Rep2 to interact with Rep1, Rep2, and DNA, suggest a model in which the Rep proteins polymerize along the 2 microm circle plasmid stability locus, forming a structure that mediates plasmid segregation. In this model, competition between Rep1 and Rep2 for association with Rep1 determines the formation or disassembly of the segregation complex.

DNA↗

PubMed2001

Family treatment and medication dosage reduction in schizophrenia: effects on patient social functioning, family attitudes, and burden.

The effects of 2 family intervention programs (supportive family management [SFM], including monthly support groups for 2 years; or applied family management [AFM], including 1 year of behavioral family therapy plus support groups for 2 years), and 3 different neuroleptic dosage strategies (standard, low, targeted) on social functioning of patients with schizophrenia. their relatives' attitudes, and family burden were examined. AFM was associated with lower rejecting attitudes by relatives toward patients and less friction in the family perceived by patients. Patients in both AFM and SFM improved in social functioning but did not differ, whereas family burden was unchanged. Medication strategy had few effects, nor did it interact with family intervention. The addition of time-limited behavioral family therapy to monthly support groups improved family atmosphere, but did not influence patient social functioning or family burden.

Adult↗

PubMed2001

Modulation of DMBA induced genotoxicity in bone marrow by quercetin during skin carcinogenesis.

Effect of quercetin was studied on DMBA induced skin carcinogenesis in young adult Swiss albino mice. Quercetin was administered continuously with the diet (2%) for four weeks and chromosomal aberration, a predictor of future cancer risk, studied in the bone marrow cells at different time intervals. Significant reduction of chromosomal aberration was observed in bone marrow after four weeks (P< 0.02). The reduction was first evident after 96 hrs though it was not significant at this stage. Significant decrease occurred from the 21st day onward when quercetin was given in concomitance with 7,12-dimethylbenz[a]anthracene (DMBA) indicating a definite protective effect of quercetin on chromosomal aberration.

9,10-Dimethyl-1,2-benzanthracene↗

PubMed2000

Treatment of dysthymia and minor depression in primary care: A randomized controlled trial in older adults.

CONTEXT: Insufficient evidence exists for recommendation of specific effective treatments for older primary care patients with minor depression or dysthymia. OBJECTIVE: To compare the effectiveness of pharmacotherapy and psychotherapy in primary care settings among older persons with minor depression or dysthymia. DESIGN: Randomized, placebo-controlled trial (November 1995-August 1998). SETTING: Four geographically and clinically diverse primary care practices. PARTICIPANTS: A total of 415 primary care patients (mean age, 71 years) with minor depression (n = 204) or dysthymia (n = 211) and a Hamilton Depression Rating Scale (HDRS) score of at least 10 were randomized; 311 (74.9%) completed all study visits. INTERVENTIONS: Patients were randomly assigned to receive paroxetine (n = 137) or placebo (n = 140), starting at 10 mg/d and titrated to a maximum of 40 mg/d, or problem-solving treatment-primary care (PST-PC; n = 138). For the paroxetine and placebo groups, the 6 visits over 11 weeks included general support and symptom and adverse effects monitoring; for the PST-PC group, visits were for psychotherapy. MAIN OUTCOME MEASURES: Depressive symptoms, by the 20-item Hopkins Symptom Checklist Depression Scale (HSCL-D-20) and the HDRS; and functional status, by the Medical Outcomes Study Short-Form 36 (SF-36) physical and mental components. RESULTS: Paroxetine patients showed greater (difference in mean [SE] 11-week change in HSCL-D-20 scores, 0.21 [0. 07]; P =.004) symptom resolution than placebo patients. Patients treated with PST-PC did not show more improvement than placebo (difference in mean [SE] change in HSCL-D-20 scores, 0.11 [0.13]; P =.13), but their symptoms improved more rapidly than those of placebo patients during the latter treatment weeks (P =.01). For dysthymia, paroxetine improved mental health functioning vs placebo among patients whose baseline functioning was high (difference in mean [SE] change in SF-36 mental component scores, 5.8 [2.02]; P =. 01) or intermediate (difference in mean [SE] change in SF-36 mental component scores, 4.4 [1.74]; P =.03). Mental health functioning in dysthymia patients was not significantly improved by PST-PC compared with placebo (P>/=.12 for low-, intermediate-, and high-functioning groups). For minor depression, both paroxetine and PST-PC improved mental health functioning in patients in the lowest tertile of baseline functioning (difference vs placebo in mean [SE] change in SF-36 mental component scores, 4.7 [2.03] for those taking paroxetine; 4.7 [1.96] for the PST-PC treatment; P =.02 vs placebo). CONCLUSIONS: Paroxetine showed moderate benefit for depressive symptoms and mental health function in elderly patients with dysthymia and more severely impaired elderly patients with minor depression. The benefits of PST-PC were smaller, had slower onset, and were more subject to site differences than those of paroxetine.

Aged↗

PubMed2000

Mechanism of neurofibrillary degeneration and pharmacologic therapeutic approach.

Neurofibrillary degeneration is a key histopathological brain lesion of Alzheimer disease (AD) and related neurodegenerative disorders such as frontotemporal dementia and Parkinsonism linked to chromosome 17 (FTDP-17), commonly referred to as tauopathies. Microtubule associated protein (MAP) tau, which is a major MAP of a normal mature neuron is abnormally hyperphosphorylated in tauopathies and is the major protein subunit of paired helical filaments (PHF)/straight filaments (SF) which accumulate in the soma (as neurofibrillary tangles) and dystrophic neurites (as neuropil threads and as dystrophic neurites surrounding the beta-amyloid core in neuritic plaques in AD) of the affected neurons. Unlike normal tau which stimulates assembly and stabilizes microtubules, the abnormally hyperphosphorylated tau inhibits assembly and disrupts microtubules. The abnormally hyperphosphorylated tau competes with tubulin/microtubules in associating with normal tau, MAP1 and MAP2. This sequestration of normal MAPs by the abnormal tau results in the breakdown of the microtubules. The association of the abnormal tau with normal tau and not with MAP1 or MAP2 results in the formation of tangles of tau filaments. All these toxic properties of the abnormally hyperphosphorylated tau are eliminated by its enzymatic dephosphorylation. Activities of phosphoseryl/phosphothreonyl protein phosphatases (PP)-2A and PP-1 which can dephosphorylate the abnormal tau to a normal-like state are compromised in AD brain. Dephosphorylation by PP-2A and PP-2B and to a lesser extent by PP-1 restores the normal microtubule assembly promoting activity in AD P-tau in vitro. Neurofibrillary tangles of PHF isolated from AD brain are also dissociated on in vitro dephosphorylation with PP-2A, and the tau released by this treatment can stimulate microtubule assembly. Thus, it appears that the abnormal hyperphosphorylation of tau leads to neurodegeneration through breakdown of the microtubule network and that the abnormal tau on association with normal tau forms neurofibrillary tangles of tau filaments i.e. PHF/SF. Increase in tau phosphatase activity is a promising approach to inhibit neurofibrillary degeneration and thereby the diseases characterized by this lesion.

Alzheimer Disease↗

PubMed2000

Engineering aspects of enzymatic signal transduction: photoreceptors in the retina.

Identifying the basic module of enzymatic amplification as an irreversible cycle of messenger activation/deactivation by a "push-pull" pair of opposing enzymes, we analyze it in terms of gain, bandwidth, noise, and power consumption. The enzymatic signal transduction cascade is viewed as an information channel, the design of which is governed by the statistical properties of the input and the noise and dynamic range constraints of the output. With the example of vertebrate phototransduction cascade we demonstrate that all of the relevant engineering parameters are controlled by enzyme concentrations and, from functional considerations, derive bounds on the required protein numbers. Conversely, the ability of enzymatic networks to change their response characteristics by varying only the abundance of different enzymes illustrates how functional diversity may be built from nearly conserved molecular components.

Animals↗

PubMed2000

Optimal tests for no contamination in reliability models.

Inferences on mixtures of probability distributions, in general, and of life distributions, in particular, are receiving considerable importance in recent years. The likelihood ratio procedure of testing for the null hypothesis of no contamination is often very cumbersome and lacks its usual asymptotic properties. Recently, SenGupta (1991) has introduced the notion of an 'L-optimal' test for such testing problems. The idea is to recast the original several parametric hypotheses representation of the null hypothesis in terms of only a single hypothesis involving an appropriately chosen parametric function. This approach is shown to be both mathematically elegant and operationally simple for a quite general class of mixture distributions which contains, in particular, all mixtures of the one-parameter exponential family and also a very rich subclass of mixtures useful in life-testing and reliability analysis. It is also illustrated through two examples--one based on real-life data and the other on a simulated sample.

Likelihood Functions↗

PubMed2000

Influences of graded dose of melatonin on the levels of blood glucose and adrenal catecholamines in male roseringed parakeets (Psittacula krameri ) under different photoperiods.

Effects of daily evening (just before the onset of darkness in a 24 h light dark cycle) administration of graded doses (25, 50, or 100 microg/100 g body wt./day for 30 days) of melatonin on the concentrations of blood glucose and adrenal catecholamines were studied in sexually active male roseringed parakeets under natural (NP; approximately 12L: 12D) and artificial long (LP; 16L: 8D) and short (SP; 8L: 16D) photoperiods. Blood samples and adrenal glands were collected from each bird during the mid-day on the following day of the last treatment. The concentrations of glucose in blood and epinephrine (E) and norepinephrine (NE) in the adrenals were measured. The results of the study indicated that exogenous melatonin induces hypo- or hyperglycemia depending on the dose of hormone administered as well as to the length of photoperiod to which birds were exposed. The levels of E and NE in the adrenals were shown also to vary in relation to photoperiod and the dose of melatonin administered. But the nature of the influence of melatonin becomes different under altered photoperiodic conditions. It appears that short photoperiods are more effective than long photoperiods as a modulator of glycemic and adrenal catecholaminergic responses to exogenous melatonin. A statistically significant correlation between the levels of blood glucose and that of E and NE in the adrenals was found in the control birds, but not in the melatonin treated birds. The results suggested that the responses of blood glucose and adrenal catecholamines to the treatment with melatonin in the roseringed parakeets may not be dependent on each other.

Adrenal Glands↗

PubMed2000

PTSD and utilization of medical treatment services among male Vietnam veterans.

This study investigated the effect of posttraumatic stress disorder (PTSD) on help-seeking for physical problems. Merging two large data sets resulted in a sample of 1773 male Vietnam veterans from white, black, Hispanic, Native Hawaiian, and Japanese American ethnic groups. Predictors of utilization included PTSD, other axis I disorders, and substance abuse. In analyses that adjusted only for age, PTSD was related to greater utilization of recent and lifetime VA medical services, and with recent inpatient care from all sources. Further analysis showed that the increased utilization associated with PTSD was not merely due to the high comorbidity between PTSD and other axis I disorders. The uniqueness of the association between PTSD and medical utilization is discussed in terms of somatization and physical illness.

Adult↗

PubMed2000

Improving the precision of primary care physician self-report of antidepressant prescribing.

BACKGROUND: Methods to select physicians most likely to benefit from educational interventions to improve the outcome of depression have not been adequately developed. OBJECTIVE: The purpose of this study was to identify a combination of primary care provider (PCP) self-report questions to improve the precision of PCP estimates of actual antidepressant prescribing as a potential tool for PCP selection. METHODS: The total number of new and refill antidepressant prescriptions written by 124 PCPs and actually filled at pharmacies over a 2-year period were matched with telephone survey results of these PCPs completed before the 2-year period. Multiple regression techniques were used to identify a set of variables that improved upon PCPs' self-report of prescriptions. RESULTS: The mean for PCP-reported antidepressant prescriptions written in the last week was 7.8 (+/-11.2). The average weekly prescriptions actually filled was 6.72 (+/-5.65). Most survey variables were significantly correlated with antidepressant prescriptions. The final model included 6 variables that explained 52% of the variance in prescriptions. In addition to PCP-reported number of antidepressants prescribed, average number of primary care patients seen per week and number of patients covered by managed care were directly related to the volume of prescriptions. PCP age, percentage of patients referred immediately without treatment, and mental health services being too far away were inversely related. CONCLUSIONS: PCP self-reports on antidepressant prescribing are reasonably accurate proxies of actual prescribing. The precision of estimates of actual prescribing can be improved by considering practice structural and financial characteristics.

Antidepressive Agents↗

PubMed2000

Predictors and outcomes of posttraumatic stress disorder in World War II veterans exposed to mustard gas.

Current posttraumatic stress disorder (PTSD) associated with participation in secret military tests of mustard gas during World War II was assessed in 363 male military veterans who were randomly sampled from a registry developed by the Department of Veterans Affairs. Current prevalence was 32% for full PTSD and 10% for partial PTSD. Prevalence of PTSD varied as a function of risk and protective factors, including volunteering, physical symptoms during the tests, and prohibited disclosure. Prediction of partial PTSD was weaker than prediction of full PTSD. Veterans with full PTSD reported poorer physical health, a higher likelihood of several chronic illnesses and health-related disability, greater functional impairment, and higher likelihood of health care use than those with no PTSD. Veterans with partial PTSD also had poorer outcomes than did veterans with no PTSD in a subset of these domains. There is discussion of the traumatic elements of experimental mustard gas exposure, vulnerability to PTSD, and the relevance of these findings to understanding the broad range of outcomes associated with PTSD.

Aged↗

PubMed2000

The relationship of aging and dysthymia in primary care.

The authors compared symptomatic and functional characteristics between older (age > or =60; n=91) and younger (age 18-59; n=125) primary care patients with dysthymia. Three of six significantly different depression symptoms were of moderate-to-large effect size, with the older group having a lower proportion reporting the symptom. The older group had a worse physical health function score but a better mental health function score. There appears to be a core of symptoms and functional impairment that generalizes across the age span. There are also significant age differences. Growing older appears to have an impact on the nature of what it means to have dysthymia.

Adult↗

PubMed2000

Gastric stromal tumours: a practical approach.

Recent findings on the pathological diversity of gastric stromal tumours and their unpredictable behaviour prompted us to review our series of 16 patients who had undergone surgery for these tumours from 1991 to 1998. There were 13 benign and 3 malignant lesions. The majority of patients presented with either upper gastrointestinal bleeding or anaemia alone (12 of 16). Endoscopy was an extremely useful diagnostic tool, revealing the lesion as an intraluminal protuberant tumour with or without ulcer in 10 cases and as an ulcer alone in 4 cases, and in 1 case features suggesting an extrinsic mass. All the patients in the series underwent surgery. We used staplers (AutosutureR TA 55) to excise the tumours in 7 cases, all of which on histological examination were benign with clear resection margins. Gastric resections were performed in 5 cases for either large tumours or those situated at the fundus or antrum and local excision of the remaining 4. The mean follow-up of these patients was 24 months. Two patients with malignant lesions died of irresectable recurrences, one 2 months and one 18 months after surgery. There have been no recurrences in the tumours diagnosed as benign on histology. Tumour size, position and the ability to apply the stapler leaving adequate margin below the tumour should be the determinants of extent and type of excision. Reliable determinants of behaviour are tumour size, grade and mitotic index.

Adult↗

PubMed2000

Palatogenesis and potential mechanisms for clefting.

This review concentrates on mechanisms of palatogenesis. This includes theories of shelf elevation, the role of matrix and identification of molecules and growth factors, which have key roles. The areas where failure to develop could potentially lead to clefting are highlighted. A key part of shelf fusion is the breakdown of the medial edge epithelium, a process that is probably dependent on enzymes involved in matrix turnover. There is good evidence that the matrix metalloproteinases may provide a common link to the multiple genetic and environmental factors that are known to cause clefting.

Cleft Palate↗

PubMed2000

Pre-clinical toxicity evaluation of leaf-stalk extractive of Piper betle Linn. in rodents.

Studies on pre-clinical toxicity were undertaken to determine the haematological and biochemical changes after administration of alcoholic extract of leaf-stalk of P. betle in rats and mice. Acute and chronic toxicity experiments were performed on mice and rats according to WHO protocol. Different doses of plant extractive were administered for toxicity studies on short and long term basis. Haematological, biochemical profiles and enzymatic studies (transaminases and phosphatases) indicated that the drug (plant extractive) was devoid of toxicity.

Animals↗

PubMed2000

Influence of photoperiods on glycemic and adrenal catecholaminergic responses to melatonin administrations in adult male roseringed parakeets, Psittacula krameri Neumann.

Effects of daily (one hour prior to onset of darkness) injection of melatonin (25 micrograms/100 g body wt. for 30 days) on concentrations of blood glucose and adrenal catecholamines were studied in adult male roseringed parakeets, P. krameri under both natural (NP; about 12L:12D) and artificial long (LP; 16L:8D; lights were available in between 0600 and 2200 hrs) or short (SP; 8L:16D; lights were available between 0600 and 1400 hrs) photoperiodic conditions. The results indicate that neither LP, nor SP as such exerts any significant effect on blood glucose titre of control (vehicle of hormone administered) birds. Treatment with melatonin, however, induced hyperglycemia in both NP and LP bird groups, but hypoglycemia in SP birds. Unlike glycemic levels, amount of epinephrine (E) and norepinephrine (NE) in adrenals of control birds exhibited significant changes under altered photoperiods. A decrease in E and an increase in NE were noted in adrenals of both LP and SP birds. Exogenous melatonin in NP birds also caused a decrease in E and concomittant rise in NE levels. On the other hand, treatment of melatonin in both LP and SP bird groups resulted in an increase in the quantity of both E and NE compared to respective values in adrenals of melatonin injected NP birds. However, relative to the amount of E and NE in adrenals of placebo treated LP and SP birds, significant effect of melatonin treatment was observed only in SP birds. The results suggest that influences of exogenous melatonin on the levels of both blood glucose and adrenal catecholamines are largely modulated by short rather than long photoperiods.

Adrenal Glands↗

PubMed1999

Characterization of minor site probes for human serum albumin by high-performance affinity chromatography.

This study used high-performance affinity chromatography (HPAC) and immobilized human serum albumin (HSA) columns to examine the specificity and cross-reactivity of various compounds that have been proposed as markers for the minor binding sites of HSA. These agents included acetyldigitoxin and digitoxin as probes for the digitoxin site, phenol red as a probe for the bilirubin site, and cisor trans-clomiphene as markers for the tamoxifen site. None of these probes showed any significant binding at HSA's indole-benzodiazepine site. However, phenol red did bind at the warfarin-azapropazone site of HSA, and cis/trans-clomiphene gave positive allosteric effects caused by the binding of warfarin to HSA. Digitoxin and acetyldigitoxin were found to bind to a common, unique region on HSA; cis- and trans-clomiphene also appeared to interact at a unique site, although trans-clomiphene displayed additional direct competition with phenol red. From these results it was possible to develop a model that described the general relationship between these binding regions on HSA. This information should be useful in future studies that employ HPAC for characterizing the binding of HSA to other drugs or clinical agents.

Binding Sites↗