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Biomedical subjects

P M Kumar

Publications and source records attributed to P M Kumar.

13 recordsLinked to original sources
PubMed2006

Bilateral cerebellar infarction: a rare complication of scorpion sting.

INTRODUCTION: Complications following scorpion sting are common in India and can be fatal. Stroke following scorpion sting is a rare complication and can occur by various mechanisms such as hypertension, hypotension, DIC, myocarditis and venom-induced vasculitis. We present a rare case of extensive cerebellar infarction following scorpion sting, which has rarely been reported in medical literature. OBJECTIVES: To study the clinical profile of two patients presenting with an acute onset of cerebellar symptoms following a scorpion sting. To evaluate the possible causes of the stroke and to study the relation of their symptoms to the scorpion sting. METHODS: Two young women presented with a history of acute onset of dysarthria, ataxia and incoordination following scorpion sting. They did not have any known risk factors for stroke. They had cerebellar type of dysarthria and cerebellar signs on both sides along with incoordination. A CT-scan of the brain showed bilateral extensive cerebellar infarctions. They were investigated for other causes of stroke without any positive results. With treatment the patients made a gradual but complete recovery. CONCLUSION: Since there was no evidence of hypertension, hypotension, myocarditis or disseminated intravascular coagulation, we can conclude that the patients had suffered a thrombotic stroke caused by the vasculotoxic action of the scorpion venom.

Acute Disease↗
PubMed2004

Marek's disease is a natural model for lymphomas overexpressing Hodgkin's disease antigen (CD30).

Animal models are essential for elucidating the molecular mechanisms of carcinogenesis. Hodgkin's and many diverse non-Hodgkin's lymphomas overexpress the Hodgkin's disease antigen CD30 (CD30(hi)), a tumor necrosis factor receptor II family member. Here we show that chicken Marek's disease (MD) lymphoma cells are also CD30(hi) and are a unique natural model for CD30(hi) lymphoma. Chicken CD30 resembles an ancestral form, and we identify a previously undescribed potential cytoplasmic signaling domain conserved in chicken, human, and mouse CD30. Our phylogeneic analysis defines a relationship between the structures of human and mouse CD30 and confirms that mouse CD30 represents the ancestral mammalian gene structure. CD30 expression by MD virus (MDV)-transformed lymphocytes correlates with expression of the MDV Meq putative oncogene (a c-Jun homologue) in vivo. The chicken CD30 promoter has 15 predicted high-stringency Meq-binding transcription factor recognition motifs, and Meq enhances transcription from the CD30 promoter in vitro. Plasma proteomics identified a soluble form of CD30. CD30 overexpression is evolutionarily conserved and defines one class of neoplastic transformation events, regardless of etiology. We propose that CD30 is a component of a critical intracellular signaling pathway perturbed in neoplastic transformation. Specific anti-CD30 Igs occurred after infection of genetically MD-resistant chickens with oncogenic MDV, suggesting immunity to CD30 could play a role in MD lymphoma regression.

Amino Acid Sequence↗
PubMed2000

A rapid technique for screening of lovastatin-producing strains of Aspergillus terreus by agar plug and Neurospora crassa bioassay.

The success of strain improvement programme depends on the number of isolates that can be screened after mutagenic treatment. A technique to rapidly screen large number of high-yielding isolates was developed. The 'agar plug' method that utilizes the anti-fungal property of lovastatin to produce a zone of inhibition against Neurospora crassa was not only economical but also less labour-intensive. We were able to isolate a high-yielding strain, the productivity of which increased by 138% as compared to the parent strain in the submerged fermentation process.

Agar↗
PubMed1979

Carcinoma of the neck in young children: a light and electron microscopic study.

Two neck tumours in young children with similar clinical features were compared using light and electron microscopy. Both tumours consisted of uniform sheets of epithelial-like cells and there were scattered stromal elements in one. Tonofilaments in sheets or bundles reminiscent of squamous epithelium were striking in the epithelial cells. Intercellular junctions were frequent but true desmosomes were not seen. Most cells contained a few secretory droplets. Occasional secretory cells, foam cells and cilia were observed. Since these tumours were not sited superficially they are unlikely to have been derived from skin epithelium. An origin in branchial sinus remnants capable of differentiation towards squamous and ciliated epithelia is suggested.

Child, Preschool↗
PubMed1978

Bone metastasizing renal tumor of childhood: morphological and clinical features, and differences from Wilms' tumor.

A bone metastasizing primary renal tumor of childhood is described, and five cases are presented. Although all five cases were originally diagnosed as nephroblastomata, there appear to be sufficient histological, ultrastructural and clinical differences to suggest that these tumors should comprise a separate and distinct entity. Using the data from the Manchester Children's Tumor Registry, the incidence of this tumor was found to be 2.3% of all primary renal neoplasms in childhood.

Bone Neoplasms↗
PubMed1978

Sorghum proteinase inhibitors: purification and some biochemical properties.

An investigation has been carried out on the proteinase inhibitors of grain sorghum (Sorghum bicolor (L.) Moench). One of the inhibitors has been isolated in a pure form and characterized. The proteinase inhibitor was extracted from the acetone-defatted sorghum meal and purified by selective thermal denaturation, ammonium sulfate fractionation, Sephadex gel filtration and DEAE-cellulose chromatography (DEAE-preparation II). This preparation was demonstrated to be a mixture of three inhibitor components by polyacrylamide disc gel electrophoresis. Further resolution of this mixture into Inhibitors I to III was achieved by QAE-Sephadex chromatography. Sorghum Inhibitor III was homogeneous by the criteria of disc gel electrophoresis and has been more fully characterized. A molecular weight of 25,000 was obtained for Inhibitor III by gel filtration and was in agreement with the value calculated from the amino acid composition of the inhibitor. The N-terminal amino acid residue of Inhibitor III, a single chain protein, was isoleucine. Sorghum proteinase inhibitors inhibit specifically the serine proteinases and are inactive towards the other classes of proteinases. Inhibitor III is primarily a chymotrypsin inhibitor, whereas Inhibitors I and II inhibit both trypsin and chymotrypsin.

Amino Acids↗
PubMed1977

Chemical modification of a pepsin inhibitor from the activation peptides of pepsinogen.

The peptide comprising the first 16 amino acids of porcine pepsinogen, prepared from the activation mixture, has been modified by guanidination of its three lysine residues to form homoarginine residues. The modified peptide is a better pepsin inhibitor than is the native peptide; for 50% inhibition of the milk-clotting action of pepsin at pH 5.3, the molar ratio of peptide to pepsin required is 9 for the native inhibitor and only 2 for the guanidinated inhibitor. Stepwise removal by Edman degradation of the amino-terminal Leu-Fal-Homoarg residues from the guanidinated inhibitor decreased the activity slightly at the first step and markedly at the second and third steps. Thus, all of the amino-terminal sequence except the leucine residue is necessary for full activity.

Amino Acid Sequence↗
PubMed1976

Cooperative interactions of tetrahydrofolate with purified pig kidney serine transhydroxymethylase and loss of this cooperativity in L1210 tumors and in tissues of mice bearing these tumors.

Serine transhydroxymethylase (5,10-methylenetetrahydrofolate: glycine hydroxymethyl transferase, EC 2.1.2.1) purified 200-fold from pig kidneys showed cooperative interactions with tetrahydrofolate with a Hill coefficient (n value) of 3.9 and a substrate concentration at 50% of maximum velocity, the S(0.5) value, of 0.5 mM. The enzyme in mouse liver and kidney homogenates also showed cooperative interactions with tetrahydrofolate. However, the enzyme obtained from L1210 solid tumors of mice, and from livers and kidneys of mice inoculated with L1210 cells exhibited hyperbolic saturation kinetics and gave a Michaelis constant, Km, value of 0.5 mM for tetrahydrofolate. The interaction of serine with the enzyme from pig kidney, from tissues of normal or tumor-bearing mice, or from L1210 tumors was hyperbolic with a Km of 0.9 mM. The specific activities of the enzyme in the L1210 tumor and in mouse liver were 10-fold higher than in pig or mouse kidney. There was no significant change in the levels of the enzyme in mouse liver and kidney on inoculation with L1210 cells. These results suggest that a tumor can bring about biochemical changes in tissues that are distal to the tumor.

Allosteric Regulation↗
PubMed1974

An electron microscope study of mitochondrial DNA in spontaneous human tumours and chemically induced animal tumours.

MtDNA was extracted by a phenol method from transplanted and primary DAB induced hepatomata in male Wistar rats, normal rat liver, spontaneous human tumours (2 Wilm's tumours, one neuroblastoma and one adrenal carcinoma), as well as 2 specimens of normal human kidney, BNU induced "leukaemias" in mice and CHO fibroblasts in monolayer culture. The proportion of monomers, catenated dimers and oligomers, open dimers and small circles was determined by electron microscopy of the fractions comprising lower and middle DNA bands in a CsCl-EthBr gradient. Tumours were compared where possible with their normal tissue of origin. Open dimers were found in 2 Wilm's tumours and their attached "normal-looking" kidney tissue but not in normal, non-malignant kidney or any other tissue studied. In Wilm's tumours, the occurrence of open dimers is far from being an all-or-none phenomenon. Malignancy produced little change in the relative proportions of catenated dimers and oligomers in the tissues studied. Small circles were found associated with mtDNA from every tissue. Tumour mtDNA was not more heterogeneous in length than monomers from the corresponding normal tissue, neither was the mean length of tumour mtDNA significantly different from its corresponding normal mtDNA.

Adrenal Gland Neoplasms↗
PubMedDate not supplied

Effects of a purified low molecular weight tumour angiogenesis factor on cell morphology of bovine brain capillary endothelial cells growing on a native collagen substratum.

A tumour angiogenesis factor (TAF) (molecular weight = 300 daltons) purified from rat Walker sarcoma was tested for its effects on the interaction of bovine capillary endothelial cells (BCEC) with a native collagen substratum in vitro. BCEC growing on collagen appeared less flattened than they were on plastic. Within five minutes of TAF addition a shape change was induced from fusiform to polygonal (p less than 0.05) and the number of spherical cells increased (p less than 0.05), implying a general cell retraction from the collagen substratum. TAF added to BCEC in suspension increased the number of cells with surface microvilli at the expense of blebbed cells (p less than 0.0001). The effect was immediate and transient. When the other parameters of cell spreading on to collagen were analysed, no difference was observed between TAF-treated cells and controls. The significance of TAF induced morphological changes are discussed with reference to the effects of polypeptide or steroid growth factors on their target cells.

Angiogenesis Inducing Agents↗