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Biomedical subjects

S K Sengupta

Publications and source records attributed to S K Sengupta.

At least 19 recordsLinked to original sources
PubMed2006

Synthesis, spectroscopic, thermal and antifungal studies on lanthanum(III) and praseodymium(III) derivatives of 1,1-diacetylferrocenyl hydrazones.

A series of new coordination complexes of La(III) and Pr(III) with hydrazones, derived from 1,1-diacetylferrocene and different aromatic acid hydrazides have been synthesized and characterized by elemental analyses, electrical conductance, magnetic moment, IR, (1)H NMR, UV-vis spectra and molar conductance. The thermal behaviour of the complexes under non-isothermal condition was investigated by TG and DTG techniques. The antifungal activity of hydrazones and their corresponding complexes were also investigated.

Antifungal Agents↗
PubMed2006

Photoconductive optically driven deformable membrane under high-frequency bias: fabrication, characterization, and modeling.

The fabrication and characterization of an optically addressable deformable mirror for a spatial light modulator are described. Device operation utilizes an electrostatically driven pixelated aluminized polymeric membrane mirror supported above an optically controlled photoconductive GaAs substrate. A 5 mum thick grid of patterned photoresist supports the 2 mum thick aluminized Mylar membrane. A conductive ZnO layer is placed on the backside of the GaAs wafer. Similar devices were also fabricated with InP. A standard Michelson interferometer is used to measure mirror deformation data as a function of illumination, applied voltage, and frequency. The device operates as an impedance distribution between two cascaded impedances of deformable membrane substrate, substrate, and electrode. An analysis of device's operation under several bias conditions, which relates membrane deformation to operating parameters, is presented.

Journal Article↗
PubMed2006

Real-time holographic deconvolution techniques for one-way image transmission through an aberrating medium: characterization, modeling, and measurements.

We propose and demonstrate a new photorefractive real-time holographic deconvolution technique for adaptive one-way image transmission through aberrating media by means of four-wave mixing. In contrast with earlier methods, which typically required various codings of the exact phase or two-way image transmission for correcting phase distortion, our technique relies on one-way image transmission through the use of exact phase information. Our technique can simultaneously correct both amplitude and phase distortions. We include several forms of image degradation, various test cases, and experimental results. We characterize the performance as a function of the input beam ratios for four metrics: signal-to-noise ratio, normalized root-mean-square error, edge restoration, and peak-to-total energy ratio. In our characterization we use false-color graphic images to display the best beam-intensity ratio two-dimensional region(s) for each of these metrics. Test cases are simulated at the optimal values of the beam-intensity ratios. We demonstrate our results through both experiment and computer simulation.

Journal Article↗
PubMed2006

Optically driven microelectromechanical-system deformable mirror under high-frequency AC bias.

A new, optically addressed deformable mirror device is demonstrated. The device consists of a pixellated metalized polymeric membrane mirror supported above an optically addressed photoconductive substrate. A conductive transparent ZnO layer is deposited on the back side of the substrate. A very high-frequency AC bias is applied between the membrane and the back electrode of the device. The membrane is deformed when the back of the device is illuminated because of impedance and bias redistribution between two cascaded impedances. We fabricated, demonstrated, and modeled the operation of this device.

Journal Article↗
PubMed2005

Organophosphorus derivatives containing piperazine dithiosemicarbazones as chemotherapeutants against fungal pathogens of sugarcane.

Five novel organophosphorus derivatives have been synthesized by the reactions of O,O-diethylchlorophosphate with piperazine dithiosemicarbazones. The derivatives have been characterized on the basis of analyses and spectral (IR, 1H NMR) data. Fungicidal activities of these derivatives against Colletotrichum falcatum, Fusarium oxysporum, and Curvularia pallescence have been evaluated. The screening results have been correlated with the structural features of the tested compounds. Organophosphorus derivatives containing 1,4-bis(4-chlorobenzaldehyde)piperazine dithiosemicarbazone and 1,4-bis(4-methoxybenzaldehyde)piperazine dithiosemicarbazone proved to be more active than some prevalent commercial synthetic fungicides.

Ascomycota↗
PubMed1999

Adult head and neck lymphomas in Papua New Guinea: a retrospective study of 70 cases.

BACKGROUND: During a 10-year period (1986-95), 70 adult Papua New Guineans with head and neck lymphomas were seen in the 18 years-and-above age group. METHODS: The clinical information was obtained from the medical records section of the Port Moresby General Hospital. Relevant treatment modalities and the follow-up data were acquired from the National Cancer Centre, Angau Memorial Hospital, Lae. RESULTS: Of a total of 227 adult lymphomas recorded in a 10-year period, 70 cases were seen in the head and neck region. Non-Hodgkin's lymphoma constituted 56 cases, which included seven cases of adult Burkitt's-like lymphoma. Fourteen cases of Hodgkin's lymphoma were recorded. CONCLUSIONS: In Papua New Guinea, malignant lymphomas primarily affecting the head and neck region were seen in 30.8% of all lymphomas. This constitues 2.8% of all malignancies in this region. These lymphomas appear to be more aggressive at this site. Proper tissue diagnosis and combination chemoradiotherapy are the key factors in its management.

Adolescent↗
PubMed1998

Paediatric head and neck lymphomas in Papua New Guinea: a review and analysis of 67 cases.

A retrospective study of head and neck lymphomas in Papua Newguinean children between the age of 0 and 12 years for a 10-year period has been attempted. A total of 67 cases are recorded. This constitutes approximately 23% of all lymphomas seen during this period. There was a male predominance in all groups. Non-Hodgkin's lymphomas (NHL) comprised of 92% of which Burkitt's lymphomas (BL) predominate (64%). Almost 50% of these cases seen were in the age group of 5-8 years. In BL, cheek swelling and upper jaw involvement are the common modes of presentation, however, in 23% of cases advanced disease with multiple sites of involvement are noted. In other NHL cases, approximately 55% presented with cervical lymphadenopathy only, maxillary sinus was affected in four cases and orbit in two cases. Histological evaluation of NHL cases excluding BL revealed two high grade, nine intermediate grade and seven low grade tumours. Hodgkin's lymphoma (HL) comprised of 8%. All cases of HL presented with cervical lymphadenopathy. Standard therapeutic modalities for lymphomas with multidrug chemotherapy, surgery and radiotherapy were followed. Proper prognostic evaluation following the treatment had not been possible in view of poor patient compliance and lack of follow up.

Child↗
PubMed1996

Nasopharyngeal osteosarcoma as second malignant neoplasm in a post-treated unilateral retinoblastoma: report of a case and review of literature.

A rare case of osteosarcoma primarily originating in the nasopharynx of an 11-year-old Papua New Guinean female who received irradiation and multi-agent chemotherapy for unilateral non-hereditary retinoblasma is described. The relevant literature is briefly reviewed. The complex role of radiation, cytotoxic drugs and genes in the development of a second malignant neoplasm in association with retinoblasma is also discussed.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1994

Heterogeneity within the Epstein-Barr virus nuclear antigen 2 gene in different strains of Epstein-Barr virus.

DNA isolated from biopsies of endemic Burkitt's lymphoma (BL) from New Guinea was analysed for the presence of Epstein-Barr virus (EBV) sequences using the polymerase chain reaction. Primers were designed to amplify sequences within the Epstein-Barr virus nuclear antigen (EBNA) 1 and 2 genes. These analyses detected the EBNA1 sequence in all the biopsies studied. Additional sets of primers directed against the EBNA2 gene were used in order to categorize the EBV strains as A-type or B-type (39% A-type; 50% B-type; 5% A- and B-type; 5% untypeable). These results indicated that DNA sequence heterogeneity within the EBNA2 gene region may exist in different strains of EBV. The extent of DNA sequence heterogeneity among different strains of EBV was determined by sequencing of a region within the EBNA2 gene in a number of different A-type and B-type strains of EBV originating from Africa or New Guinea. The results demonstrated DNA sequence heterogeneity within the EBNA2 gene in different strains of EBV. This heterogeneity was more extensive among A-type strains than B-type strains of EBV.

Africa↗
PubMed1993

Surgical thyroid disease in Papua New Guinea.

A clinical and histopathological analysis was carried out on 376 thyroid specimens removed under various diagnoses from the surgical clinics of Papua New Guinea over a period of 11 years (1980-90). Solitary nodular goitre (solid and cystic) was the most common clinical diagnosis. Nineteen per cent of the solid and 35% of the cystic solitary nodular goitres were found to be malignant. Malignant goitres were confirmed histologically in 73.3% of the clinically diagnosed cases of malignancy. The presence of amyloid goitre (1.9%) posed a significant diagnostic and therapeutic problem due to its clinical features resembling that of malignant goitre. Hemithyroidectomy (lobectomy) was the most common surgical procedure employed for all unilateral thyroid lesions and partial or subtotal thyroidectomy was performed for benign and most malignant lesions.

Adolescent↗
PubMed1992

The spectrum of cancer in Papua New Guinea. An analysis based on the Cancer Registry 1979-1988.

Malignant tumors registered with the Tumour Registry of Papua New Guinea (PNG) from 1958-1988 were analyzed with emphasis on the variation of incidence with time and different regions. Cancer incidence was generally low in PNG. During this period, carcinoma of oral cavity, cervix, breast, and skin, hepatoma, and lymphoma were the most common types of malignant lesions detected. The incidence of carcinoma of the oral cavity has increased. Currently, it is more common in the Highlands region and is associated with the spread of betel nut chewing. A threefold increase in cervical carcinoma registration was observed nationally, with a sixfold increase in the Highlands region; this was attributed both to social changes and improved registration. The incidence of breast cancer has doubled, in keeping with better registration, but there is little interregional variation. The decline in registrations of hepatocellular carcinoma is artifactual. PNG is a high-incidence area for Burkitt lymphoma, but Hodgkin disease is rare. Both Burkitt and other non-Hodgkin lymphomas are uncommon in the Highlands. A decline in the incidence of squamous carcinoma of skin was observed that was associated with improved control of tropical ulcers. The incidence of stomach cancer is falling. The registered cancer incidence in PNG is low, even when compared with that in native people from other Pacific nations, such as Fijians and New Caledonian Melanesians. Preventive measures have been hitherto ineffective, with the exception of squamous carcinoma of skin.

Adult↗
PubMed1991

Gastric stenosis following the ingestion of car battery acid.

The acute consequences of the ingestion of corrosive substances include acute necrosis of the upper gastrointestinal tract, haemorrhage and perforation. Late complications include the development of stenotic lesions. A case of fibrous gastric stenosis following the ingestion of car battery acid is presented. Endoscopically, the appearances were consistent with gastric carcinoma.

Adult↗
PubMed1989

Road traffic accident fatalities in Port Moresby: a ten-year survey.

A retrospective analysis for a 10-year period (1976-1985) of Road Traffic Accident (RTA) fatalities was carried out in Port Moresby, the capital of Papua New Guinea. The majority of the victims were males and under the age of 45. Passengers formed the largest number, followed by pedestrians and drivers. Most fatal accidents occurred during the weekend. Analysis of injuries reveal head injury to be the dominant and possible cause of death in all three categories of victims. Multiple injuries involving many organs were more common in pedestrians and passengers than drivers. Factors contributing to the high rate of RTAs are discussed and measures to minimise the rate of such accidents have been suggested.

Accidents, Traffic↗