Search PubMed⌕ Search

Biomedical subjects

V Gupta

Publications and source records attributed to V Gupta.

At least 163 records · Page 9Linked to original sources
PubMed1998

Adaptive variations of undulatory behaviors in larval lamprey: comparison of swimming and burrowing.

In larval lamprey, movements and muscle activity during swimming and burrowing behaviors were compared. Burrowing consisted of two components: an initial component in which the head was driven into the burrowing medium; and a final component in which the animal pulled the rest of its body into the burrowing medium. The initial component of burrowing was characterized by large undulatory movements and rhythmic muscle burst activity that were similar in form to those during fast swimming, but more intense. During the initial component of burrrowing, burst durations, burst amplitudes, and burst proportions of motor activity were larger than those during swimming, while cycle time was slightly shorter than during swimming. Intersegmental phase lags and right-left phase values were similar for swimming and initial burrowing. The final component of burrowing was characterized by sharp, long-duration flexures on one side of the body, sometimes followed by similar flexures on the other side. Each flexure was produced by long-duration, large-amplitude muscle burst activity on the same side of the body or several shorter sequential bursts with slightly smaller amplitudes. During the final component of burrowing, burst durations and burst amplitudes of motor activity were much larger than those during swimming or during the initial component of burrowing. It is suggested that the motor patterns for swimming and the initial component of burrowing are produced by a common spinal locomotor network. The final component of burrowing may use some of the same neurons in the spinal locomotor networks, but the networks are probably configured differently than the situation during swimming.

Adaptation, Physiological↗
PubMed1998

Identification of polymorphic mutant alleles of CaMDR1, a major facilitator of Candida albicans which confers multidrug resistance, and its in vitro transcriptional activation.

CaMDR1 (Candida albicans Multi Drug Resistance) encodes a major facilitator whose expression in Saccharomyces cerevisiae confers resistance to several unrelated drugs. We describe here the identification and molecular characterization of seven mutant alleles of CaMDR1 (CaMDR1-1 to 1-7). The complete sequencing of CaMDR1 alleles revealed several in-frame point mutations leading to a change in amino-acid residues where insertion/replacement of an aspartate residue in a serine-asparagine-aspartate-rich domain was most noteworthy. Interestingly, these alleles showed a distinct drug resistance profile. The expression of CaMDR1, or of its alleles, in C. albicans cells was enhanced by benomyl, methotrexate and several other unrelated drugs, and was more pronounced in at least one of the azole-resistant clinical isolates.

Alleles↗
PubMed1998

Primary cutaneous aspergillosis: our experience in 10 years.

We describe nine patients with primary cutaneous aspergillosis who were diagnosed during the 10-year period between 1987 and 1996. All except one were adults. Seven of those nine cases had an immunocompromised state. Among the immunocompromised patients, six had burn wounds and one was a renal transplant recipient. Aspergillus flavus was isolated from seven patients and A. fumigatus from one, and in one other case the species could not be determined. Three patients who had total burn surface area of more than 70% died. The other patients responded well to extensive surgical debridement with or without institution of oral itraconazole.

Adult↗
PubMed1998

Social capital, income inequality, and firearm violent crime.

Studies have shown that poverty and income are powerful predictors of homicide and violent crime. We hypothesized that the effect of the growing gap between the rich and poor is mediated through an undermining of social cohesion, or social capital, and that decreased social capital is in turn associated with increased firearm homicide and violent crime. Social capital was measured by the weighted responses to two items from the U.S. General Social Survey: the per capita density of membership in voluntary groups in each state; and the level of social trust, as gauged by the proportion of residents in each state who believed that "most people would take advantage of you if they got the chance". Age-standardized firearm homicide rates for the years 1987-1991 and firearm robbery and assault incidence rates for years 1991-1994 were obtained for each of the 50 U.S. states. Income inequality was strongly correlated with firearm violent crime (firearm homicide, r = 0.76) as well as the measures of social capital: per capita group membership (r = -0.40) and lack of social trust (r = 0.73). In turn, both social trust (firearm homicide, r = 0.83) and group membership (firearm homicide, r = -0.49) were associated with firearm violent crime. These relationships held when controlling for poverty and a proxy variable for access to firearms. The profound effects of income inequality and social capital, when controlling for other factors such as poverty and firearm availability, on firearm violent crime indicate that policies that address these broader, macro-social forces warrant serious consideration.

Homicide↗
PubMed1998

Balloon angioplasty for the treatment of coronary in-stent restenosis: immediate results and 6-month angiographic recurrent restenosis rate.

OBJECTIVES: The purpose of this prospective study was to evaluate the immediate results and the 6-month angiographic recurrent restenosis rate after balloon angioplasty for in-stent restenosis. BACKGROUND: Despite excellent immediate and mid-term results, 20% to 30% of patients with coronary stent implantation will present an angiographic restenosis and may require additional treatment. The optimal treatment for in-stent restenosis is still unclear. METHODS: Quantitative coronary angiography (QCA) analyses were performed before and after stent implantation, before and after balloon angioplasty for in-stent restenosis and on a 6-month systematic coronary angiogram to assess the recurrent angiographic restenosis rate. RESULTS: Balloon angioplasty was performed in 52 patients presenting in-stent restenosis. In-stent restenosis was either diffuse (> or =10 mm) inside the stent (71%) or focal (29%). Mean stent length was 16+/-7 mm. Balloon diameter of 2.98+/-0.37 mm and maximal inflation pressure of 10+/-3 atm were used for balloon angioplasty. Angiographic success rate was 100% without any complication. Acute gain was lower after balloon angioplasty for in-stent restenosis than after stent implantation: 1.19+/-0.60 mm vs. 1.75+/-0.68 mm (p=0.0002). At 6-month follow-up, 60% of patients were asymptomatic and no patient died. Eighteen patients (35%) had repeat target vessel revascularization. Angiographic restenosis rate was 54%. Recurrent restenosis rate was higher when in-stent restenosis was diffuse: 63% vs. 31% when focal, p=0.046. CONCLUSIONS: Although balloon angioplasty for in-stent restenosis can be safely and successfully performed, it leads to less immediate stenosis improvement than at time of stent implantation and carries a high recurrent angiographic restenosis rate at 6 months, in particular in diffuse in-stent restenosis lesions.

Angioplasty, Balloon, Coronary↗
PubMed1998

Efficacy of diode laser for managing diabetic macular oedema.

PURPOSE: To evaluate the effect of photocoagulation for diabetic macular oedema using Diode laser in a prospective randomized fashion and comparing its effects with the Argon green laser. METHODS: 40 eyes with focal and diffuse oedema were randomly treated with Diode and 40 eyes were treated with Argon green. Following investigations were performed: visual acuity, fundus evaluation, flourescein angiography and visual fields. RESULTS: 79% treated with Diode had partial to complete regression of oedema and so also 82% with Argon green at six months post laser. CONCLUSIONS: There was no difference in improvement or worsening of visual acuity between the two lasers. This study is of importance as it has been the first prospective randomized study of its kind using Diode laser in diabetic macular oedema.

Diabetes Mellitus, Type 2↗
PubMed1998

Management of presumed intraocular tuberculosis: possible role of the polymerase chain reaction.

PURPOSE: A highly selective technique of polymerase chain reaction (PCR) was performed for detection of Mycobacterium tuberculosis from aqueous samples of 45 patients to evaluate its role in initiating antituberculosis treatment in patients with presumed intraocular tuberculosis. METHODS: Forty-five patients were divided into three groups. Group I included 17 patients of presumed intraocular tuberculosis, group II 13 disease controls and group III had 15 normal controls. Patients with positive PCR were offered antituberculosis chemotherapy and followed up for a minimum of 18 months. RESULTS: Ten patients in group I, 3 in group II and none in group III were positive for Mycobacterium tuberculosis by PCR. Ten patients with positive PCR for Mycobacterium tuberculosis (8 in group I and 2 in group II) were treated with antituberculosis chemotherapy and all showed resolution of inflammation without any recurrence over 18 months of follow-up. Two PCR positive patients treated with steroids alone, however, did not show complete resolution and had recurrent attacks. CONCLUSION: These results suggest that antituberculosis treatment in PCR positive patients leads to resolution of inflammation and elimination of recurrences, most likely by eliminating Mycobacterium tuberculosis from the intraocular tissues.

Adolescent↗
PubMed1998

Normoxic wound fluid contains high levels of vascular endothelial growth factor.

OBJECTIVE: To examine the temporal integration of vascular endothelial growth factor (VEGF), which has been shown to be present in wound fluid, with the putatively related processes of wound fluid oxygen content, wound angiogenesis, and granulation tissue formation. SUMMARY BACKGROUND DATA: During cutaneous wound repair, new tissue formation starts with reepithelialization and is followed by granulation tissue formation, including neutrophil and macrophage accumulation, fibroblast ingrowth, matrix deposition, and angiogenesis. Because angiogenesis and increased vascular permeability are characteristic features of wound healing, VEGF may play an important role in tissue repair. METHODS: A ventral hernia, surgically created in the abdominal wall of female swine, was repaired using silicone sheeting and skin closure. Over time, a fluid-filled wound compartment formed, bounded by subcutaneous tissue and omentum. Ultrasonography was performed serially to examine the anatomy and dimensions of the subcutaneous tissue and wound compartment. Serial wound fluid samples, obtained by percutaneous aspiration, were analyzed for PO2, PCO2, pH, and growth factor concentrations. RESULTS: Three independent assays demonstrate that VEGF protein is present at substantially elevated levels in a wound fluid associated with the formation of abdominal granulation tissue. However, the wound fluid is not hypoxic at any time. Serial sampling reveals that transforming growth factor beta-1 protein appears in the wound fluid before VEGF. CONCLUSIONS: The results suggest that VEGF is a prominent regulator of wound angiogenesis and vessel permeability. A factor other than hypoxia, perhaps the earlier appearance of another growth factor, transforming growth factor beta-1, may positively regulate VEGF appearance in the wound fluid.

Abdominal Muscles↗
PubMed1997

A new treatment for severe pulmonary embolism: percutaneous rheolytic thrombectomy.

BACKGROUND: The rheolytic thrombectomy catheter has been specially designed to remove intravascular thrombus from coronary and peripheral arteries. It demonstrates a practical application of Bernoulli's principle relating to a low-pressure zone in the region of a high-velocity jet. In this device, this effect is created by direct high-pressure saline jets located at the tip. Thrombus is drawn into this region and, because of the large pressure difference, undergoes mechanical thrombolysis due to the powerful mixing forces. The resulting microparticles are aspirated through the same catheter and removed from the body. METHODS AND RESULTS: We report the use of this device in two patients presenting with severe pulmonary embolism and contraindications to thrombolytic therapy. The two procedures were successfully performed with an excellent immediate angiographic result at the site of the rheolytic thrombectomy. In both cases, the clinical improvement was maintained at follow-up with the same good angiographic result and a decrease to a normal level of the systolic pulmonary pressure. CONCLUSIONS: This preliminary results suggest that this easy technical method may be useful in the treatment of life-threatening pulmonary embolism in patients with absolute contraindications to thrombolytic therapy. A larger cohort of patients is necessary to determine whether this treatment should be proposed as an alternative to the use of fibrinolytics in selected patients.

Aged↗
PubMed1997

A model for binding of structurally diverse natural product inhibitors of protein phosphatases PP1 and PP2A.

Protein phosphatases play significant roles in signal transduction pathways pertaining to cell proliferation, gene expression, and neurotransmission. Serine/threonine phosphatases PP1 and PP2A, which are closely related in primary structure (approximately 50%), are inhibited by a structurally diverse group of natural toxins. As part of our study toward understanding the mechanism of inhibition displayed by these toxins, we have developed research in two directions: (1) The standardization of an assay to be used in acquisition of the structure--activity relationship of inhibition data is reported. This nonradioactive assay affords detection levels of molecular phosphate released from a phosphorylated hexapeptide in subnanomolar quantities. The comparison of our IC50 values of these inhibitors against corresponding literature data provided validation for our method. (2) Computational analysis provided a global model for binding of these inhibitors to PP1. The natural toxins were shown to possess remarkably similar three-dimensional motifs upon superimposition and van der Waals minimization within the PP1 active site.

Antifungal Agents↗
PubMed1997

Mechanism of increased sensitivity to etoposide in a mitomycin C-resistant human bladder cancer cell line.

The mechanism of increased sensitivity to etoposide (VP-16) in a human bladder cancer cell line (J82/MMC-2), which is >9-fold more resistant to mitomycin C (MMC) compared with parental cells (J82/WT), was investigated. Colony formation assays, following 1 hr drug exposure, revealed that about a 2.2-fold higher concentration of VP-16 was required to kill 50% of the J82/WT cell line compared with J82/MMC-2. The MTT assays, following continuous drug exposure, also showed that the J82/MMC-2 cell line was significantly more sensitive to VP-16 compared with J82/WT. Accumulation of VP-16 was significantly higher in the J82/MMC-2 cell line compared with J82/WT at every drug concentration tested. Likewise, intracellular VP-16 retention was significantly higher in the J82/MMC-2 cell line compared with J82/WT when drug uptake was measured as a function of varying incubation time and at a fixed VP-16 concentration. The efflux of VP-16 from the J82/MMC-2 cell line was equivalent to that from J82/WT. In agreement with the results of drug uptake studies, the levels of VP-16-induced protein-DNA complexes were markedly higher in the J82/MMC-2 cell line compared with J82/WT. The catalytic activity of topoisomerase II (topo II) in 0.35 M NaCl nuclear extract of J82/WT cells was equivalent to that of J82/MMC-2. The levels of topo II mRNA were also comparable in these cells. Our results suggest that the mechanism responsible for the collateral sensitivity of the J82/MMC-2 cell line to VP-16 may be attributable to a relatively higher drug accumulation in this cell line compared with parental cells.

Antineoplastic Agents, Phytogenic↗
PubMed1997

Alterations in lipid composition and neuronal injury in primates following chronic aluminium exposure.

The effect of chronic aluminium exposure (25 mg/kg b.wt.) was studied on the lipid composition and various membrane-bound enzymes in different regions of monkey brain. Aluminium (Al) administration caused a significant decrease in the total lipid, glycolipid, and phospholipid content of primate brain. Cholesterol levels and the phospholipid to cholesterol ratio were, however, markedly increased as a consequence of Al administration, thereby indicating a loss of membrane integrity. This was further confirmed when Al treatment was found to have a significant effect on the various membrane-bound enzymes in terms of decreased activities of Na+ K+ ATPase and acetylcholinesterase, along with a decrease in the activity of the myelin-specific enzyme, 2' 3'-cyclic nucleotide phosphohydrolase.

Aluminum↗
PubMed1997

Positional MRI: a technique for confirming the site of leakage in cerebrospinal fluid rhinorrhoea.

We report confirmation of the site of leakage in two patients with spontaneous cerebrospinal fluid (CSF) rhinorrhoea by demonstrating CSF leaking on MRI. Both patients had midline anterior cranial fossa floor (cribriform plate/fovea ethmoidalis) dural-bone defects with arachnoid herniation with or without brain herniation into the upper part of the nasal cavity on MRI, which was subsequently confirmed surgically. Corresponding to the history of postural induction or aggravation of the rhinorrhoea, the CSF leak was demonstrated by the appearance of or increase in the sinonasal fluid collection by imaging the patient in the position of maximum leakage following initial images in the supine position.

Cerebrospinal Fluid Rhinorrhea↗
PubMed1997

Effects of a randomized health education intervention on aspects of reproductive health knowledge and reported behaviour among adolescents in Zimbabwe.

Unwanted teenage pregnancy and the attendant morbidity and mortality necessitate an understanding of the factors influencing adolescent sexuality and the implementation of programmes designed to improve their knowledge and reproductive behaviour. A randomized controlled study on reproductive health knowledge and behaviour was undertaken among adolescent pupils drawn from a multi-stage random cluster sample. A self-administered questionnaire was used to assess aspects of reproductive health knowledge and behaviour at baseline followed by a health education intervention, except for control schools. Results are based on 1689 responses made up of 1159 intervention and 530 control respondents. There was a significant increase in correct knowledge about aspects of menstruation in intervention as compared with control schools [odds ratio (OR) = 4.5, 95% confidence interval (CI) = 3.4-6.1). Significantly, (OR = 2.0, 95%CI = 1.1-3.9) more pupils from intervention than control schools scored correctly on practice relating to menstruation. Pupils from intervention schools were more likely (P < 0.001) to know that a boy experiencing wet dreams could make a girl pregnant and that a girl could get pregnant at her first sexual intercourse (OR = 1.4, 95%CI = 1.1-1.9). Knowledge of family planning was low in both groups at baseline but was high at five months follow-up in the intervention schools. The findings point to the need for early school-based reproductive health education programmes, incorporating correct information on reproductive biology and the subsequent prevention of reproductive ill health.

Adolescent↗
PubMed1997

Fractal analysis of surface EMG signals from the biceps.

Nonlinear analysis techniques are necessary to understand the complexity of the EMG. The purpose of the present study was to determine the fractal dimension of surface EMG obtained from the biceps brachii of normal subjects during isokinetic flexion-extension of the arm. The measurements were obtained with different loading conditions on the arm and for various rates of flexion-extension. Fractal dimensions of the surface EMG signals were calculated for each of these conditions. ANOVA results showed statistically significant differences between the fractal dimensions calculated for different loading conditions and rates of flexion-extensin (P < or = 0.005). Linear regression analysis showed a correlation coefficient of 0.99 between the fractal dimension and the load, and a correlation coefficient of 0.98 between the fractal dimension and the rate of flexion-extension. The results of the study show that the fractal dimension can be used along with other parameters to characterize the EMG signal.

Algorithms↗
PubMed1997

Characterization of a BMS-181174-resistant human bladder cancer cell line.

This study was undertaken to elucidate the mechanism of cellular resistance to BMS-181174, a novel analogue of mitomycin C (MMC), in a human bladder cancer cell line. The BMS-181174-resistant variant (J82/BMS) was established by repeated continuous exposures of parental cells (J82) to increasing concentrations of BMS-181174 (9-40 nM) over a period of about 17 months. A 2.6-fold higher concentration of BMS-181174 was required to kill 50% of J82/BMS cell line compared with J82. The J82/BMS cell line exhibited collateral sensitivity to 5-fluorouracil (5-FU), but was significantly more cross-resistant to MMC, melphalan, taxol, doxorubicin and VP-16. NADPH cytochrome P450 reductase and DT-diaphorase activities, which have been implicated in bioreductive activation of MMC, were significantly lower in the J82/BMS cell line than in J82. The cytotoxicity of BMS-181174, however, was not affected in either cell line by pretreatment with dicoumarol, which is an inhibitor of DT-diaphorase activity. These results argue against a role of DT-diaphorase in cellular bioactivation of BMS-181174, a conclusion consistent with that of Rockwell et al (Biochem Pharmacol, 50: 1239-1243, 1995). BMS-181174-induced DNA interstrand cross-link (DNA-ISC) frequency was markedly lower in J82/BMS cell line than in J82 at every drug concentration tested. The results of the present study suggest that cellular resistance to BMS-181174 in J82/BMS cell line may be due to reduced DNA-ISC formation. However, the mechanism of relatively lower BMS-181174 induced DNA-ISC formation in J82/BMS cell line than in parental cells remains to be clarified.

Antineoplastic Agents, Alkylating↗
PubMed1997

MR evaluation of CSF fistulae.

PURPOSE: To evaluate the role of MR imaging in the localisation of cerebrospinal fluid (CSF) fistulae. MATERIAL AND METHODS: A total of 36 consecutive unselected patients with either clinically proven CSF leakage (n=26) or suspected CSF fistula (n=10) were prospectively evaluated by MR. All MR examinations included fast spin-echo T2-weighted images in the 3 orthogonal planes. Thin-section CT was performed following equivocal or negative MR examination. MR and CT findings were correlated with surgical results in 33 patients. RESULTS: CSF fistula was visualised as a dural-bone defect with hyperintense fluid signal continuous with that in the basal cisterns on T2-weighted images. MR was positive in 26 cases, in 24 of which the fistula was confirmed surgically. In 2 patients the CSF leakage was directly demonstrated on MR. MR sensitivity of 80% compared favourably with the reported 46-81% of CT cisternography (CTC). No significant difference in MR sensitivity in detecting CSF fistula was found between active and inactive leaks CONCLUSION: MR is recommended as the first investigation for detecting a CSF fistula owing to its efficacy and to its freedom from the potential complications encountered with CTC.

Adolescent↗