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Biomedical subjects

A Gupta

Publications and source records attributed to A Gupta.

At least 37 records · Page 2Linked to original sources
PubMed2006

Chordoid meningioma, an uncommon variant of meningioma: a clinicopathologic study of 12 cases.

AIMS: The study has been undertaken to document the clinicopathological features of 12 cases of chordoid meningioma, operated at All India Institute of Medical Sciences during 1996 to June 2005. METHODS: Clinical information was retrieved from the records of our Neurosurgery Department. The cases were stained with H&E, Periodic Acid Schiff (PAS) with and without diastase, mucicarmine, giemsa, toluidine blue, alcian blue, reticulin and Masson trichrome. Immunohistochemistry for pancytokeratin, epithelial membrane antigen, vimentin, glial fibrillary acidic protein, MIB-1, Leucocyte common antigen (LCA), CD-3 and CD-20 was done in all cases. RESULTS: The age ranged from 12-67 years (mean 34.2 years) and three of them occurred in < 18 years. Male to female ratio was 1:1.4. The duration of symptoms varied from 3.5 months to 5 years (mean 14.1 months). No systemic symptoms were noted. The location of tumor in eight cases was in the supratentorial and rest four in the infratentorial compartments. Interestingly, two cases were in intraventricular location, one in the lateral ventricle and other in the fourth ventricle. Microscopic examination showed lobulation with chordoid elements constituting > 95% of the entire tumor area in 11 of the total 12 cases. In one case, chordoid pattern constituted about 30% of the total tumor area; the rest was predominant meningothelial (60%). Mild to severe lymphoplasmacytic cell infiltrate was present in all cases. The histochemical stains showed the pattern of acidic mucin and interestingly revealed the presence of mast cells both in connective tissue stroma and epithelial cell islands. The inflammatory infiltrate was B-cell predominant. MIB-1 labeling index was low (< 2%) in all cases except two, which showed LI of 6% and 8%. Strong diffuse immunoreactivity for vimentin and focal positivity for epithelial membrane antigen was noted in all cases. CONCLUSIONS: Chordoid meningiomas are predominantly tumors of young adults with predilection for supratentorial location. Intraventricular location, absence of systemic manifestations despite the presence of abundant B-lymphocytes, presence of mast cells and low MIB-1 LI are some of the interesting findings in the present series, which need documentation. Hence, larger number of cases with adequate follow-up data need to be studied further to establish the clinical significance of this variant.

Adolescent↗
PubMed2006

Stanmore non-invasive growing arthrodesis endoprosthesis in the reconstruction of complicated total knee arthroplasty: A case report.

As the number of primary and revision arthroplasties performed each year increases, the complexity of the reconstructive efforts also increases. A case of a patient with a total knee arthroplasty complicated with infection, deficient extensor mechanism, bone loss and limb shortening of 5.5 cm is reported. We describe an alternative surgical technique of reconstruction of the knee and lengthening of the limb using the Stanmore Non-Invasive Growing-Distal Femoral Prosthesis. The prosthesis had a magnetic disc attached to a gearbox. The generation of an external electromagnetic field caused the magnetic disc to rotate and lengthen the prosthesis. This reconstructive technique has not been described in the literature.

Anti-Bacterial Agents↗
PubMed2006

Postoperative seizures after extratemporal resections and hemispherectomy in pediatric epilepsy.

OBJECTIVES: To estimate frequency and risk factors for acute postoperative seizures (APOS) within the first week after extratemporal cortical resection (ETR) and hemispherectomy (HS) in children and to assess the predictive value of APOS on long-term seizure outcome in this group. METHODS: The authors conducted a retrospective analysis of children (< 18 years), who underwent ETR or HS for intractable epilepsy between 1995 and 2002. APOS features and seizure outcome after ETR or HS were obtained at 6, 12, and 24 months. Univariate logistic regression was used for risk factors of APOS and life table analysis and log rank tests for seizure outcome at 0 to 6, 6 to 12, and 12 to 24 months. RESULTS: Of 132 patients, 34 (26%) had APOS. APOS were more frequent after ETR (26/71) than HS (8/61) (p < 0.01). APOS, irrespective of their timing, number, semiology, or other perioperative complications, were an independent predictor of poor postoperative seizure outcome at 2 years (p < 0.001). The estimated odds of postoperative Engel class I outcome in the APOS vs non-APOS categories was 0.27 (73% less likely) for 0- to 6-month, 0.22 (78% less likely) for 6- to 12-month, and 0.13 (87% less likely) for the 12- to 24-month intervals. CONCLUSIONS: Acute postoperative seizures (APOS) occur in 26% children, and the risk is higher after extratemporal cortical resection than hemispherectomy. APOS predict a poor postoperative seizure outcome at 6, 12, and 24 months. This study is useful for counseling families after epilepsy surgery. It also suggests that APOS may not be discounted as "benign" in research studies that evaluate seizure outcomes after epilepsy surgery.

Adolescent↗
PubMed2006

Ultrasound biomicroscopic quantification of the change in anterior chamber angle following laser peripheral iridotomy in early chronic primary angle closure glaucoma.

AIMS: To prospectively evaluate by ultrasound biomicroscopy (UBM) and gonioscopy the anterior chamber angle widening following laser peripheral iridotomy (LPI) in eyes with early chronic primary angle closure glaucoma (CACG). METHODS: A total of 55 eyes of 55 patients with CACG presenting with less than 180 degrees peripheral anterior synechiae (PAS) were enrolled in the study. Angles were assessed by gonioscopy (Shaffer's grading) and UBM, before and 4 weeks after LPI. The angle opening distance at 250 and 500 microm from the scleral spur (AOD 250 and AOD 500) was computed. Results were analysed using the Wilcoxon signed-rank test. RESULTS: In the quadrant with LPI, the mean gonioscopy grade increased significantly from 0.45 to 1.45 (P<0.001) and the mean AOD 250 and AOD 500 increased from 38.5+/-25.9 to 83.5+/-48.4 microm (P<0.001) and 110.2+/-80.9 to 170.6+/-83.4 microm (P<0.001), respectively. The angles widened significantly in the opposite quadrant on UBM (AOD 250: 48.8+/-31.5-82.7+/-43.9 microm, P<0.001; AOD 500:117.2+/-65.5-172.2+/-81.7 microm; P<0.001), but the median gonioscopy grade remained unchanged. CONCLUSIONS: LPI significantly widened the anterior chamber angle in the quadrant with LPI and the quadrant furthest away in patients of CACG with established glaucomatous damage. This change was much better appreciated by the UBM than gonioscopy.

Adult↗
PubMed2006

A spin triplet supercurrent through the half-metallic ferromagnet CrO2.

In general, conventional superconductivity should not occur in a ferromagnet, though it has been seen in iron under pressure. Moreover, theory predicts that the current is always carried by pairs of electrons in a spin singlet state, so conventional superconductivity decays very rapidly when in contact with a ferromagnet, which normally prohibits the existence of singlet pairs. It has been predicted that this rapid spatial decay would not occur if spin triplet superconductivity could be induced in the ferromagnet. Here we report a Josephson supercurrent through the strong ferromagnet CrO2, from which we infer that it is a spin triplet supercurrent. Our experimental set-up is different from those envisaged in the earlier predictions, but we conclude that the underlying physical explanation for our result is a conversion from spin singlet pairs to spin triplets at the interface. The supercurrent can be switched with the direction of the magnetization, analogous to spin valve transistors, and therefore could enable magnetization-controlled Josephson junctions.

Journal Article↗
PubMed2006

Relevance of rodent models of intravenous MDMA self-administration to human MDMA consumption patterns.

RATIONALE: Despite decades of research specifying harmful effects produced by 3,4-methylenedioxymethamphetamine (MDMA; a principal component of 'ecstasy' pills), young people (and adults) continue to use it. In an attempt to model human MDMA consumption patterns, preclinical investigators have sought to establish reliable patterns of intravenous MDMA self-administration in rodents. OBJECTIVE: The objective of this report is to offer a critical review of published data (including our own novel findings) that reveal MDMA self-administration in rodents. RESULTS: The data indicate that MDMA serves as a reinforcer in rodents, though the responses are not similar to those previously reported for psychostimulants (i.e., cocaine). Important differences between rodent models and human use patterns include frequency of dosing and dosage exposure, routes of administration, tolerance that develops to MDMA after repeated exposure, polydrug use in humans but not by rodents, limits on the repertoire of behaviors that can be exhibited by rodents undergoing IV self-administration procedures, and the question of neurotoxicity as it relates to models of self-administration. CONCLUSIONS: While MDMA is not as potent a reinforcer as other drugs of abuse, the fact remains that young people and adults continue to use the drug, and therefore, additional research is needed to determine why drugs with low reinforcing effects continue to be abused.

Animals↗
PubMed2006

The enigmatic origin of subfrontal schwannomas: report of a case without hyposmia.

Subfrontal schwannomas are rare intracranial tumors. Most of them are associated with hyposmia/anosmia. The source of origin of these tumors is still incompletely understood. We report a 23-year-old male who presented with recurrent focal motor seizures, but had no hyposmia. The tumor was completely removed by a subfrontal approach. Relevant literature has been reviewed.

Adult↗
PubMed2006

Evaluation of community-based serologic screening for identification of chronic Salmonella typhi carriers in Vietnam.

OBJECTIVES: To determine the utility of screening anti-Vi antibodies to detect chronic Salmonella Typhi carriers in an endemic community. METHODS: We conducted a community-based serologic survey for anti-Vi antibodies to identify chronic Salmonella Typhi carriers in a typhoid endemic region in Vietnam. RESULTS: We tested sera from 3209 (67.2%) of 4772 eligible adults. The median age was 37 years (range 20-92), 57.3% were female, 4.6% reported a history of typhoid fever and 0.3% reported typhoid vaccination. Anti-Vi antibody titers tested in Vietnam were < 1:40 in 2759 (86.0%), 1:40 in 194 (6.0%), 1:80 in 168 (5.2%), 1:160 in 57 (1.8%), and > or = 1:320 in 31 (1.0%). On re-testing in the USA, an additional 19 sera with titers > or = 1:160 were identified. We collected 589 rectal swabs from 103 (96.3%) of 107 persons with Vi antibody titers > or = 1:160 and 183 swabs from 33 persons with antibody titers < 1:80. No Salmonella Typhi was isolated. CONCLUSIONS: Community-based serologic screening is a feasible, but impractical method for identifying chronic Salmonella Typhi carriers. Background levels of anti-Vi antibody titers in this endemic area may be high despite a low prevalence of chronic carriers.

Adult↗
PubMed2006

[Suggestion for a new, patient-oriented epilepsy classification].

The recent proposal by the ILAE Task Force for Epilepsy Classification is a multiaxial, syndrome-oriented approach. Epilepsy syndromes--at least as defined by the ILAE Task Force--group patients according to multiple, usually poorly defined parameters. As a result, these syndromes frequently show significant overlap and may change with patient age. We propose a five-dimensional and patient-oriented approach to epilepsy classification. This approach shifts away from syndrome orientation, using independent criteria in each of the five dimensions similarly to the diagnostic process in general neurology. The main dimensions of this new classification consist of (1) localizing the epileptogenic zone, (2) semiology of the seizure, (3) etiology, (4) seizure frequency, and (5) related medical conditions. These dimensions characterize all information necessary for patient management, are independent parameters, and include information more pertinent than the ILAE axes with regard to patient management. All cases can be classified according to this five-dimensional system, even at initial encounter when no detailed test results are available. Information from clinical tests such as MRI and EEG are translated into the best possible working hypothesis at the time of classification, allowing increased precision of the classification as additional information becomes available.

Epilepsy↗
PubMed2006

Hibernoma: MRI features in eight consecutive cases.

AIM: To describe the preoperative magnetic resonance imaging findings of eight histologically-proven cases of hibernoma. MATERIALS AND METHODS: The site, size, and signal characteristics of eight consecutive hibernomas were retrospectively assessed on T1-weighted spin-echo and short T1 inversion recovery (STIR)/fat-saturated T2-weighted fast spin echo magnetic resonance images. Four patients also had gadolinium-enhanced fat-saturated T1-weighted spin echo imaging. Patient age and sex, and duration of symptoms were recorded. RESULTS: Three female and five male patients with an average age 36 years (range 16-53 years) were included. Seven lesions occurred in the thigh, four in the anterior compartment and three in the posterior compartment. One lesion occurred superficial to the scapula. All cases demonstrated common magnetic resonance imaging findings of a well-defined, heterogeneous mass, slightly or clearly hypo-intense to subcutaneous fat on T1-weighted spin-echo images, with prominent thin low signal bands throughout the tumour. The lesions failed to fully suppress on STIR or fat-saturated T2-weighted images. Only one of the four contrast-enhanced studies demonstrated increased vascularity in the tumour. CONCLUSION: The MRI findings of a lesion that is diffusely slightly hypointense to surrounding subcutaneous fat, should prompt the operator to consider hibernoma in the differential diagnosis.

Adipocytes, Brown↗
PubMed2006

Raman scattering from high-frequency phonons in supported n-graphene layer films.

Results of room-temperature Raman scattering studies of ultrathin graphitic films supported on Si (100)/SiO2 substrates are reported. The results are significantly different from those known for graphite. Spectra were collected using 514.5 nm radiation on films containing from n = 1 to 20 graphene layers, as determined by atomic force microscopy. Both the first- and second-order Raman spectra show unique signatures of the number of layers in the film. The nGL film analogue of the Raman G-band in graphite exhibits a Lorentzian line shape whose center frequency shifts linearly relative to graphite as approximately 1/n (for n = 1 omegaG approximately 1587 cm-1). Three weak bands, identified with disorder-induced first-order scattering, are observed at approximately 1350, 1450, and 1500 cm-1. The approximately 1500 cm-1 band is weak but relatively sharp and exhibits an interesting n-dependence. In general, the intensity of these D-bands decreases dramatically with increasing n. Three second-order bands are also observed (approximately 2450, approximately 2700, and 3248 cm-1). They are analogues to those observed in graphite. However, the approximately 2700 cm-1 band exhibits an interesting and dramatic change of shape with n. Interestingly, for n < 5 this second-order band is more intense than the G-band.

Journal Article↗
PubMed2006

High-throughput evaluation of non-swellable controlled release matrix tablets.

Drug release from controlled-release (CR) matrix tablets involves the permeation and diffusion of water through the system. In this study, a new methodology is proposed for the measurement of water permeation and simultaneous drug release from the inert, non-swellable CR matrix tablet of diltiazem (DLT) and a correlation is made between these two processes. Cylindrical matrices were readily prepared by direct compression of pellets obtained by extrusion-spheronization. Water transport was studied using tritiated water (HTO) as a permeant in a Franz-diffusion cell and simultaneously drug release was measured. Further, dissolution was performed on USP XXI/XXII dissolution apparatus I using demineralized water. Matrices showed a steady water-uptake up to 6 h and the steady state for HTO permeation lasting from 6-h to 24-h Flux of water permeated and flux of drug released correlated well. Thus, HTO permeation through the matrix tablet and the proposed methodology can be used as a tool and/or surrogate marker for evaluation of controlled release matrix tablets. This methodology can be coined as "high-throughput" in terms of amount of labor and resources required in comparison to that of dissolution.

Delayed-Action Preparations↗
PubMed2006

Removal of Cr (VI) from aqueous solutions by Acacia nilotica bark.

Removal of hexavalent Cr from aqueous solutions by bark of Acacia nilotica L. was studied in batch process. Different parameters of adsorption viz. effect of pH, effect of dose and effect of contact time were studied. The percentage removal of Cr (VI) from synthetic sample was found to be 89.0 and 93.1% for 1.0 mm and 0.3 mm Acacia bark carbon (ABC) respectively and 60.9% and 68.1% for 1.0 mm and 0.3 mm Acacia bark untreated (ABU) respectively, in 30 min contact time. The optimum pH for both adsorbents was found to be 2.0 and adsorption equilibrium was found to be 30 min. for both adsorbents. The adsorption process was found to follow first order rate mechanism as well as Freundlich isotherm.

Acacia↗
PubMed2006

Low HIV-1 incidence among married serodiscordant couples in Pune, India.

Unlike commercial sex workers and patients attending sexually transmitted infection (STI) clinics, married couples are not typically targeted for HIV risk reduction programs in India. Thus, married partners of HIV-infected persons are at particularly high risk for HIV infection. Between September 2002 and November 2004, 457 HIV-1 sero-discordant, married couples were enrolled in a one-year prospective study of HIV transmission in Pune, India. The HIV incidence among uninfected partners was 1.22 per 100 person-years (95% CI 0.45-2.66), which is much lower than what has been previously reported among discordant couples in Africa. This may be due to higher rates of condom use, lower rates of STIs and higher CD4 T lymphocyte counts, among the Indian HIV sero-discordant couples.

Adult↗
PubMed2006

Expression of CD34 as a novel marker for glioneuronal lesions associated with chronic intractable epilepsy.

The spectrum of glioneuronal lesions underlying intractable epilepsies includes malformative pathologies like focal cortical dysplasia (FCD); and neoplastic lesions like gangliogliomas (GG) and dysembryoplastic neuroepithelial tumours (DNT). These may occur either singly or as dual lesions, having simultaneous presence of both elements. Currently, the relationship between the malformative and neoplastic glioneuronal lesions is poorly understood. Recently, CD34, a stem cell marker transiently expressed during early neurulation, has been identified in these tumours. This study was undertaken to (i) evaluate the role of CD34 as a diagnostic marker for glioneuronal lesions of epilepsy, namely, GG, DNT and FCD, and (ii) attempt to define the relationship among these lesions, using CD34 as a marker. Tissues resected from 47 patients with intractable epilepsy due to glioneuronal lesions (GG, FCD, DNT) were studied. These were evaluated for CD34 expression, using immunohistochemistry. Dysplastic or atypically differentiated neural precursors which could not be identified on routine haematoxylin and eosin (H&E) staining were highlighted by CD34 immunostaining. The pattern of immunostaining was diffuse in GGs, unlike FCDs, wherein cells were present singly or in small clusters. However, cases of DNT and control tissue were largely CD34-immunonegative. Based on these findings, we propose a possible common origin of GG and FCD, from a bipotent precursor that undergoes abnormal glioneuronal development, while DNTs possibly have a different origin. The CD34-immunoreactive cells represent dysplastic or undifferentiated neural precursors, which may signify a valuable marker for the diagnostic evaluation of neoplastic and/or malformative pathologies in patients with intractable epilepsy.

Adolescent↗