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Biomedical subjects

P S Sastry

Publications and source records attributed to P S Sastry.

At least 19 recordsLinked to original sources
PubMed2004

Fingerprint classification using a feedback-based line detector.

We present a fingerprint classification algorithm in this paper. This algorithm classifies a fingerprint image into one of the five classes: Arch, Left loop, Right loop, Whorl, and Tented arch. We use a new low-dimensional feature vector obtained from the output of a novel oriented line detector presented here. Our line detector is a co-operative dynamical system that gives oriented lines and preserves multiple orientations at points where differently oriented lines meet. Our feature extraction process is based on characterizing the distribution of orientations around the fingerprint. We discuss three different classifiers: support vector machines, nearest-neighbor classifier, and neural network classifier. We present results obtained on a National Institute of Standards and Technology (NIST) fingerprint database and compare with other published results on NIST databases. All our classifiers perform equally well, and this suggests that our novel line detection and feature extraction process indeed captures all the crucial information needed for classification in this problem.

Journal Article↗
PubMed2000

Apoptosis and the nervous system.

Apoptosis is now recognized as a normal feature in the development of the nervous system and may also play a role in neurodegenerative diseases and aging. This phenomenon has been investigated intensively during the last 6-7 years, and the progress made in this field is reviewed here. Besides a few in vivo studies, a variety of neuronal preparations from various parts of the brain, the majority of which were primary cultures, and some cell lines have been investigated. Several apoptosis-inducing agents have been identified, and these include lack of neurotrophic support, neurotransmitters, neurotoxicants, modulators of protein phosphorylation and calcium homeostasis, DNA-damaging agents, oxidative stress, nitric oxide, and ceramides. The precise signaling cascade is not well established, and there are lacunae in many suggested pathways. However, it appears certain that the Bcl family of proteins is involved in the apoptotic pathway, and these proteins in turn affect the processing of interleukin-1beta converting enzyme (ICE)/caspases. The available evidence suggests that there may be several apoptotic pathways that may depend on the cell type and the inducing agent, and most of the pathways may converge at the ICE/caspases step.

Animals↗
PubMed2000

Transmissible spongiform encephalopathies and the 'rogue share-holder protein' hypothesis.

Transmissible spongiform encephalopathies(TSEs) or prion diseases are a closely related group of diseases, whose exact etiology is unknown, but is generally accepted to be related to protease-resistant prion protein PrP. PrPc is normally present in cells and its disease counterpart PrPsc is postulated to occur due to a rare stochastic change. The selfish gene hypothesis is a generally well accepted concept in evolutionary biology. Genes can be likened to the board of a company and proteins can be likened to share-holders. Here it is being hypothesized that a rogue share-holder protein's 'selfish' replicatory tendency might be the explanation for TSEs. The present hypothesis predicts existence of other examples of rogue share-holder protein and also predicts that examples would be found in lower life-forms as well.

Animals↗
PubMed2000

Ex vivo expanded allogeneic cord blood progenitor cell transplantation with a non-myeloablative conditioning regimen would cure autoimmune diseases.

Loss of self-tolerance is the basis for autoimmune disease. Autologous as well as allogeneic stem cell transplantation is increasingly being considered and used for therapy of autoimmune disease. Non-myeloablative conditioning has been shown in the context of malignant diseases to be feasible. Cord blood transplantation has been associated with significantly less graft-versus-host disease (GVHD) than other forms of allotransplantation. Ex-vivo expansion of this limited resource is increasingly becoming feasible. It is being hypothesized that ex-vivo expanded cord blood progenitor cell transplantation using a non-myeloablative conditioning regimen would be curative in autoimmune diseases.

Autoimmune Diseases↗
PubMed1999

Role of feedback in mammalian vision: a new hypothesis and a computational model.

This paper presents a novel hypothesis on the function of massive feedback pathways in mammalian visual systems. We propose that the cortical feature detectors compete not for the right to represent the output at a point, but for exclusive rights to abstract and represent part of the underlying input. Feedback can do this very naturally. A computational model that implements the above idea for the problem of detection is presented and based on that we suggest a functional role for the thalamo-cortical loop during perception of lines. We show that the model successfully tackles the so called Cross problem. Based on some recent experimental results, we discuss the biological plausibility of our model. We also comment on the relevance of our hypothesis (on the role of feedback) to general sensory information processing and recognition.

Algorithms↗
PubMed1999

Adoptive immunotherapy for cutaneous T-cell lymphomas.

The pathology of cutaneous T-cell lymphomas is predominantly in the skin. Allogeneic bone-marrow transplantation results in graft-versus-host disease involving the skin in many cases. It has been suggested that it would be interesting to see the effect of allotransplantation, even though no series has been reported so far. Adoptive immunotherapy with donor lymphocyte infusions has been increasingly used to treat post-transplant relapse and even prevention. The present hypothesis suggests that infusion of human leucocyte antigen (HLA)-matched donor lymphocyte infusions would result in a graft-versus-leukemia/lymphoma (GVL) effect in these disorders. Therefore, clinical trials are suggested.

Graft vs Host Reaction↗
PubMed1999

Inhibition of TNF-alpha synthesis with thalidomide for prevention of acute exacerbations and altering the natural history of multiple sclerosis.

Multiple sclerosis (MS) is a common neurological disorder which has a relapsing/remitting course and is presently incurable. A variety of agents have been tried to prevent excerbations and alter the natural history of the disease. Tumor necrosis factor-alpha (TNF-alpha) has been implicated as the most important cytokine in the pathogenesis of MS. There is evidence that thalidomide is an agent which blocks production of TNF-alpha by a mechanism different from other agents. Hence it is hypothesized that using thalidomide as therapy would prevent acute exacerbations of MS as well as alter its natural history.

Disease Progression↗
PubMed1999

Prevention of progression in chronic myeloid leukemia by altering DNA methylation with a pyridoxine analogue.

Altered DNA methylation is one mechanism by which progression might occur in tumors. Progression in chronic myeloid leukemia (CML) was initially thought to be due to mutations. However, altered DNA methylation might be responsible for the same. An agent whose probable target is DNA methylation has been shown to improve hematopoiesis in CML. Pyridoxine is involved in methylation reactions. At present, the link between dietary factors like pyridoxine and cancer is somewhat tenuous. It is hypothesized that a suitable pyridoxine analogue might, by blocking DNA methylation, prevent progression in CML.

DNA Methylation↗
PubMed1997

Pulmonary microsporidial infection in a patient with CML undergoing allogeneic marrow transplant.

Very few cases of human microsporidial infection have been reported. The advent of AIDS has changed this. There is increasing recognition that microsporidia are important opportunistic pathogens. However, the number of cases reported in the non-HIV population is small. We report here a case of microsporidial infection in a female patient with chronic myeloid leukemia undergoing allogeneic bone marrow transplantation. There was also an associated fungal infection. The diagnosis could be reached only after postmortem and was confirmed by electron micrography. We suggest that transplant patients are another group of patients who are susceptible to this group of opportunistic pathogens.

Adult↗
PubMed1997

Gonadal function following ABVD therapy for Hodgkin's disease.

To assess the effect of combination chemotherapy with doxorubicin, bleomycin, viablastine, and decarbazine (ABVD) on gonadal function in patients treated for Hodgkin's disease, we assessed 38 male patients with Hodgkin's disease who were > 15 years of age and in complete remission for the development of secondary sexual characteristics, sexual habits, and fatherhood after treatment. Semen analysis and serum hormone level estimation of follicle-stimulating hormone (FSH), leutinising hormone (LH), and testosterone (T) were done in all cases. Twenty-six patients received ABVD therapy and 12 received a combination of ABVD with COPP or MOPP (cyclophosphamide or nitrogen mustard, vincristine, procarbazine, and prednisone). Radiation of the pelvic region was done in one case. Median time between completion of therapy and assessment of gonadal function was 34 months (range, 12-68 months). Secondary sexual characteristics developed normally in all patients. Azoospermia was seen in one patient from the ABVD group and 10 patients from the COPP/ABVD group (p < 0.001). Serum FSH levels were significantly higher in the COPP/ABVD group than in the ABVD group (23.5 versus 4.7 mlu/ml; p < 0.001) The levels were in the normal range in 23 patients from the ABVD group, as compared to four in the COPP/ABVD group (88.5% versus 33.3%; p < 0.001). Three patients treated with ABVD fathered children post-therapy. We conclude that ABVD is associated with relatively better preservation of gonadal function.

Adolescent↗
PubMed1997

Serum tumor necrosis factor for monitoring response of hepatic veno-occlusive disease to pentoxiphyllin--a case report.

Hepatic veno-occlusive disease (VOD) is the second most common cause of death after autologous bone marrow transplantation (ABMT). A patient with multiple myeloma undergoing ABMT developed classic features of hepatic VOD. He responded to treatment with pentoxiphyllin. Serum tumor necrosis factor (TNF) levels showed remarkable correlation with the severity of VOD and response to therapy.

Adult↗
PubMed1997

Antilymphocyte globulin (ALG) or antithymocyte globulin (ATG) with methylprednisone and oxymethalone in aplastic anaemia.

From 1986 to 1994 we treated 26 patients of aplastic anaemia between 6 to 61 years age group with ATG/ALG, Methylprednisone and Oxymethalone. Five had very severe aplastic anaemia, 16 had severe and 5 nonsevere disease. Disease was associated with hepatitis in 5 patients and with pregnancy and drug use in 2 patients each. In others no cause could be ascertained. A total of 31 courses of treatment were given (range 1-3 courses per patient). Nine patients had complete response (34.62%) and 3 had partial response (11.54%) with an overall response rate of 46.16%. Four patients died within 2 months of starting the treatment. The median follow up was 24 months (range 6-102 months) with an overall survival probality of 45% at 2 yr. At the time of evaluation 12 patients have died, 9 are alive disease-free and 5 are alive with disease. The side effects associated with therapy were tolerable and did not require cessation of therapy in any patient. We conclude that ATG/ALG with Methylprednisone and Oxymethalone is beneficial to significant number of patients with aplastic anaemia.

Adolescent↗
PubMed1995

Rapid cytoreduction in childhood leukemic hyperleukocytosis by conservative therapy.

Childhood leukemic hyperleukocytosis poses a serious threat to life because of its associated metabolic complications. The present prospective trial utilized conservative management of childhood acute lymphoblastic leukemia with hyperleukocytosis (total white cell count equal or > 100 x 10(9)/L) by intravenous hydration, urinary alkalinization, and allopurinol presenting without severe life-threatening complications. The median reduction in WBC count was 81.51% (range: 66-98.8%) within a median period of 36 hours (range: 12-60 hours) following hospitalization. There were no failures or treatment related complications. Thus we conclude that in childhood acute lymphoblastic leukemia, hyperleukocytosis can be managed safely and effectively with intravenous hydration, urinary alkalinization, and allopurinol before starting any specific anti-leukemic chemotherapy avoiding risk-associated cranial irradiation, leukapheresis, and exchange transfusion.

Adolescent↗
PubMed1995

Purification and partial characterization of acyl carrier proteins from developing oil seeds of pisa (Actinodaphne hookeri) and ground nut (Arachis hypogaea).

Acyl carrier proteins (ACP) were purified to homogeneity in the active form from developing seeds of pisa (Actinodaphne hookeri) which synthesizes exclusively trilaurin and from ground nut (Arachis hypogaea) which synthesizes triacylglycerols containing long chain fatty acids. Two major isoforms of ACPs were purified from developing pisa seeds using DEAE-cellulose, Superose-6 FPLC and C4 reversed phase HPLC chromatographic methods. In contrast, only a single form of ACP was present in ground nut seeds which was purified by anion-exchange and activated thiol-Sepharose 4B affinity chromatography. The two isoforms of ACPs from pisa showed nearly the same specific activity of 6,706 and 7,175 pmol per min per mg protein while ground nut ACP showed a specific activity of 3,893 pmol per min per mg protein when assayed using E. coli acyl-ACP synthetase and [1-14C]palmitic acid. When compared with E. coli ACP, the purified ACPs from both the seeds showed considerable difference in their mobility in native PAGE, but showed similar mobility in SDS-PAGE under reducing conditions. In the absence of reducing agents formation of dimers was quite prominent. The ACPs from both the seed sources were acid- and heat-stable. The major isoform of pisa seed ACP and the ground nut ACP contain 91 amino acids with M(r) 11,616 and 1,228 respectively. However, there is significant variation in their amino acid composition. A comparison of the amino acid sequence in the N-terminal region of pisa and ground nut seed ACPs showed considerable homology between themselves and with other plant ACPs but not with E. coli ACP.

Amino Acid Sequence↗
PubMed1995

A soluble preparation from developing groundnut seeds (Arachis hypogaea) catalyzes de novo synthesis of long chain fatty acids.

A 100,000 x g supernatant fraction prepared from developing groundnut seeds (30-35 days after flowering) catalyzed the synthesis of fatty acids from [l-14C]acetate at a rate of 120nmoles of acetate incorporated per hr per gram fresh weight of tissue. 90% of this incorporated label was associated with fatty acids. The major fatty acids formed were stearic- (77%) and palmitic acids (14%) with 4% of oleic acid. The fatty acid synthetase activity was stable when stored at 0-4 degrees C for at least fifteen days. It is concluded from these results that acetyl-coA carboxylase and all the enzymes of fatty acid synthetase from developing groundnut seeds are soluble.

Arachis↗