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Biomedical subjects

P Ramanathan

Publications and source records attributed to P Ramanathan.

At least 19 recordsLinked to original sources
PubMed2002

HIV-1 viral protein R compromises cellular immune function in vivo.

HIV-1 viral protein R (Vpr) is a virion-associated gene product that profoundly affects T cell proliferation, induces apoptosis and can affect cytokine production in part through interfering with NF-kappa B-mediated transcription from host cells. Collectively, these effects support that Vpr could influence immune activation in vivo. However, this effect of Vpr has not been explored previously. Here we examined the effect of Vpr expression in an in vivo model system on the induction of antigen-specific immune responses using a DNA vaccine model. Vpr co-vaccination significantly altered the immune response to co-delivered antigen. Specifically, in the presence of Vpr, inflammation was markedly reduced compared to antigen alone. Vpr reduced antigen-specific CD8-mediated cytotoxic T lymphocyte activity and suppressed T(h)1 immune responses in vivo as evidenced by lower levels of IFN-gamma. In the presence of Vpr, there is a profound shift in isotype towards a T(h)2 response as determined by the IgG2a:IgG1 ratio. The data support that Vpr compromises antigen-specific immune responses and ultimately effector cell function, thus confirming a strong selective advantage to the virus at the expense of the host.

AIDS Vaccines↗
PubMed2002

Evaluation of mosquitocidal activity of Annona squamosa leaves against filarial vector mosquito, Culex quinquefasciatus Say.

Methanolic extract of leaves of A. squamosa was tested for mosquitocidal effect against C. quinquefasciatus. A liquid mosquito insecticide formulation was prepared with the extract (1, 3 and 5 %w/w) using deodorized kerosene as solvent and investigated for its knock-down and 24 hr mortality. The extract formulation produced dose dependent activity, exhibited significantly shorter knock down KD50 and KD90 values and produced significant mortality. The results suggest the potential mosquitocidal effect of A. squamosa on C. quinquefasciatus.

Animals↗
PubMed2000

Nocardia asteroides pericarditis in association with HIV.

This case report describes Nocardia pericarditis in a newly diagnosed human immunodeficiency virus (HIV) patient as an initial manifestation. Previously, two cases of Nocardia pericarditis were reported in patients with established HIV infection. To our knowledge this is the first case of Nocardia pericarditis as an initial manifestation of HIV infection. This case substantiates and emphasizes the importance of identifying Nocardia as an infectious cause of pericarditis in patients with acquired immunodeficiency. Long-term survival may be achieved with a combined medical and surgical approach.

AIDS-Related Opportunistic Infections↗
PubMed1993

Bone scans in neuroblastoma.

Eighty-Six patients of neuroblastoma ranging in age from four months to 15 years were studied with 99m Tc-MDP for total skeletal survey over a period of seven years (1983-1990). The diagnosis of neuroblastoma was based on bone marrow examination, FNAC, lymph node biopsy, histopathology. Bone imaging was performed three hrs. after intravenous administration of 99m Tc-MDP. Out of 86 patients, 45 patients had positive bone scan showing osseous concentration in 122 sites and extraosseous concentration in 34 sites. Seven patients had liver metastases. None of these liver metastases showed concentration of MDP. Fourteen patients underwent surgery for the primary tumour at the time of bone scanning. Ten patients were studied at the time of follow up, of which four patients showed good response as bony metastases were not demonstrated on bone scintigraphy and X-rays. In conclusion, bone scan is an useful test in neuroblastoma in delineating the bony metastases and also in assessing the efficacy of chemotherapy in these patients.

Abdominal Neoplasms↗
PubMed1992

Utility of technetium-t-butyl isonitrile (99mTc-TBI) myocardial imaging in coronary artery disease.

99mTc-t-butyl isonitrile is a useful agent for myocardial perfusion imaging. The superior physical advantages of technetium over 201thallium make larger doses possible for imaging. Accumulation in the myocardium is unidirectional in that once attached it does not leave the myocardium and hence two separate injections are needed for rest and stress imaging. High liver uptake frequently conceals the inferior wall and high early uptakes make immediate post-injection imaging almost impossible at least up to 45-60 min. This agent, however, was seen to accurately identify under-perfused areas and distinguish between ischaemia and infarct in our patients. Agreement with 201Tl and with GBP study of regional wall motion was excellent. While its individual sensitivity and specificity are quite high at 82.6 and 90.9%, in combined GBP studies the sensitivity rose to 93.4%. It is concluded that Tc-TBI is a valuable agent for myocardial perfusion scintigraphy, especially in a developing country like India where Tc-MIBI cannot be routinely used, since it is expensive, and where regular supplies of 201Tl are also not always feasible due to the high cost of importing. 99mTc-TBI can be made cheaply here and in a select population, notably in those with left anterior descending and circumflex coronary artery disease, it can provide valuable information.

Coronary Angiography↗
PubMed1991

Regional distribution study of brain perfusion and metabolic agents in normal and tumour bearing rat brains using autoradiographic technique.

Regional distribution of brain perfusion imaging agents, [131I]N,N,N'-trimethyl-N'-[2-hydroxy-3-methyl-5-iodobenzyl]1,3 propanediamine (HIPDM) and [131I]-N-isopropyl-p-iodoamphetamine (IMP), was compared with the distribution of patterns of [14C]L-methionine and [14C]D-glucose in normal and tumour bearing rat brains using autoradiographic technique. There was higher concentration of the radiopharmaceutical in grey than white matter in normal rat brain. Autoradiographs of brain tumour sections showed very low uptake of [131I]HIPDM and [131I]IMP as compared to normal brain tissue. There was moderate concentration of [14C]D-glucose and avid uptake of [14C]L-methionine in tumours. Autoradiographic study is useful for evaluating distribution patterns of radiopharmaceuticals.

Amphetamines↗
PubMed1990

Preparation and evaluation of 99mTc-t-butylisonitrile (99mTc-TBI) for myocardial imaging: a kit for hospital radiopharmacy.

A previous method was modified to obtain [99mTc(TBI)6]+ by reacting Zn(TBI)2Br2 directly with 99mTcO4- in the presence of Sn2+ ions. [Cu(TBI)4]Cl was next used as a source of TBI. On reaction with 99mTcO4- and Sn2+ ions for 3 min at 100 degrees C, [99mTc(TBI)6]+ product of radiochemical purity greater than 90% and yield greater than 70% was obtained. Data of biodistribution in rats (2-2.5% in heart) and biokinetics in rabbits were satisfactory. The kit formulation was found to be stable and also safe for administration.

Animals↗
PubMed1990

Visualization of suppressed thyroid tissue by technetium-99m-tertiary butyl isonitrile: an alternative to post-TSH stimulation scanning.

The autonomously functioning thyroid nodule (AFTN) is a discrete, nodular structure which operates independently of pituitary control and without relation to the remaining thyroid tissue. Presently, for the visualization of a suppressed thyroid lobe, a patient has to undergo the thyrotropin (TSH) stimulation test, which has several disadvantages. In this study we have used tertiary butyl isonitrile (99mTc-TBI), well known as a myocardial imaging agent, for visualization of the suppressed lobe. Thirteen of fourteen patients studied demonstrated a contralateral lobe on a 99mTc-TBI scan which was not visualized with a 99mTc0(4) or 131I scan. Although it is not possible to demonstrate the autonomous nature of the hyperfunctioning thyroid nodule using 99mTc-TBI, we conclude that it is feasible to use this agent to visualize the lobe without the TSH test.

Adult↗
PubMed1988

Clinical evaluation of 99mTc(V)-dimercapto succinic acid (DMSA) for imaging medullary carcinoma of thyroid and its metastasis.

99mTc(V)-DMSA kits developed by the Radiopharmaceutical Division, Bhabha Atomic Research Centre, have been evaluated for potential use in scanning medullary carcinoma of the thyroid and its metastases. There were 15 patients with proved medullary carcinoma and 6 patients with other differentiated thyroid carcinoma. Amongst the 15 patients with medullary carcinoma, 12 (80%) showed positive localisation either in the primary or one or more metastatic sites. None of the six patients with carcinoma other than medullary showed increased concentration of 99mTc(V)-DMSA. Of the 37 known metastatic sites in 15 patients with medullary carcinoma, 24 showed concentration of 99mTc(V)-DMSA (64.9%). In addition, 99mTc(V)-DMSA concentration was seen in 14 sites where no evidence of metastasis was revealed. The incidence of 99mTc(V)-DMSA concentration in soft tissue and bone metastasis was similar.

Adult↗
PubMed1987

Preparation and evaluation of 99mTc(V)-DMSA complex: studies in medullary carcinoma of thyroid.

Consequent to the promising results reported with 99mTc(V)-DMSA for imaging certain types of soft tissue tumors, we have developed methods to prepare this radiopharmaceutical in three ways: from freshly prepared reagents, through the use of a two component kit and use of the standard renal DMSA kit by a modified recipe. The 99mTc(V)-DMSA complex has been subjected to paper electrophoretic and chromatographic procedures and also biodistribution studies. The distinctly different behaviour of this new product compared to that of the well known renal DMSA complex has been clearly established. Scintiimaging in a preliminary clinical trial in patients with medullary carcinoma of the thyroid has been encouraging.

Carcinoma↗
PubMed1981

Pitfalls in the lateral imaging of the thyroid with pinhole collimators.

Imaging of the thyroid gland with pinhole collimators in the lateral projection is associated with the problem of count rate contribution from the contralateral lobe. In a series of experiments conducted using a thyroid-simulating phantom, the contribution of this nature was calculated. Radioisotopes of different energies such as 99mTc and 131I were used to see the effect of energy on this contribution. It was observed that the count rate contribution from the contralateral lobe to the lobe proximal to the collimator can be as high as 70% at a distance of 6 cm from the collimator. At distances more than 6 cm these contributions from the contralateral lobe are much more than this.

Iodine Radioisotopes↗
PubMed1980

Scan appearances in hydatid cysts of the liver: analysis of 55 cases.

Liver scans done at our Centre between 1964 and 1977 were analyzed with reference to hydatid cysts in liver. Among the approximately 7200 patients analyzed, there were 55 suspected to have hydatid cysts. The criteria adopted in screening the patients for hydatid cysts were based upon clinical findings and liver scan findings. The cases were analyzed with respect to their histologic findings, locations of cold areas in the liver, and correlation with Casoni's test. We found that 1) the cystic involvement was most often in the right lobe of the liver; 2) Casoni's test does not rule out or establish the presence of hydatidosis; 3) radioisotopic vascular studies done in some cases contributed to the diagnosis; 4) although a positive liver scan does not indicate the cause of the disease, the scans showing large and totally photon-deficient cold areas along with good general condition of the patients help in the diagnosis of hydatid cysts in the liver.

Colloids↗
PubMed1978

Efficacy of brain scanning in epilepsy of late onset.

Brain scans of 513 patients with epilepsy of late onset were analysed with reference to the patient's age and sex and to the nature of convulsion. Only 17 of them showed an abnormal concentration of radionuclide indicating a space-occupying lesion in the brain. The findings of those patients who had positive brain scans were correlated with EEG findings. It was found that the incidence of epilepsy of late onset is almost 3 times higher in males than in females and that the age cannot be considered as a criterion for screening the patients for brain scan investigations as far as epilepsy of late onset is concerned. In our opinion, the incidence of 3.3% is not too low. A positive brain scan finding calls for further investigation and helps in deciding the management and further line of treatment of the patients. Moreover, a normal scan rules out the presence of a space-occupying lesion and helps as a screening procedure.

Adult↗
PubMed1977

Frequency of inferior vena caval abnormalcy due to a juxtaposed pathology.

Radionuclide inferior vena cavagrams were done in 135 patients who had hepatomegaly, splenomegaly or a mass in the vicinity of the inferior vena cava (I.V.C.). 2-5mCi 66mTc phytate, 99mTc S colloid, 99mTc O4-, 99mTc-LIDA, 99mTc pyridoxyledene glutamate or 113mIn colloid were injected directly and rapidly into either a malleolar or a femoral vein while the patient lay supine under the 13.5'' detector head of a scinticamera. Rapid sequential scintiphotos were manually taken at approximately 1 sec. interval for 20-30 sec. Thus iliac vein, I.V.C., cardiopulmonary zone in infants, aorta and the arterial phase were visualized. 48% of these subjects had an abnormal I.V.C. and the depictions were interestingly varied, indicating that different patients responded in a different manner even to grossly similar pathologies. It became evident that this soft walled vessel could be compressed by both fluids and neoplastic tissue (Fig. 1, 2); the long I.V.C. channel could also be segmentally pushed away by a mass in its vicinity. (Fig. 2, 3, 4). An abnormal arterial flush usually differentiated between benign (Fig. 2) and malignant (Fig. 3) lesions, even when the mass was extra-hepatic (Fig. 4) and retiroperitoneal (Fig. 5). Such a systematic study of I.V.C. had not been possible earlier since the classical x-ray contrast inferior vena cavagram necessitates venous dissection, passage of a catheter, and the injection of large volume of fluid under an unphysiologically high pressure. The simplified radionuclide technique, however, permitted the study of neonates and critically ill subjects with massive ascites, while retaining a satisfactory reproducability.

Abdominal Muscles↗
PubMed1977

Radionuclide inferior vena cavagram.

Routine visualisation of the I.V.C. at the time of injection for hepatosplenic scintigraphy may sometimes yield useful information. 4 such instances are reported.

Child↗