Radioisotope scintigraphy in the diagnosis of hepatic hydrothorax.

Background: Pleural effusion in cirrhotic patients (hepatic hydrothorax) may result from migration of ascitic fluid across defects in the diaphragm. Biochemical analysis of ascitic and pleural fluid provides only indirect information about the nature and origin of the effusion. The present study was performed in order to demonstrate the presence/absence of peritoneo-pleural communication by radioisotope imaging.

Oxidative damage of erythrocytes: a possible mechanism for premature hemolysis in experimental visceral leishmaniasis in hamsters.

Visceral leishmaniasis is accompanied by severe anemia and pancytopenia. Reactive oxygen species are known to contribute to the pathogenesis of several red blood cell (RBCs) disorders. The present study reveals the extent of oxidative stress and the efficacy of the primary antioxidant system in erythrocytes of hamsters in the progressive anemic response at different stages of leishmanial infection.

Interaction of ascorbate and alpha-tocopherol enhances antioxidant reserve of erythrocytes during anemia in visceral leishmaniasis.

Visceral leishmaniasis (V.L.) is associated with enhanced lipid peroxidation along with impaired function of antioxidant defense system in erythrocytes.

Role of porin of Shigella dysenteriae type 1 in modulation of lipopolysaccharide mediated nitric oxide and interleukin-1 release by murine peritoneal macrophages.

The ability of Shigella dysenteriae type 1 porin to induce the release of nitric oxide (NO) and interleukin-1 (IL-1) from peritoneal macrophages of mouse and to regulate lipopolysaccharide (LPS) and gamma interferon (IFN-gamma) mediated release of the two proinflammatory mediators was investigated. Porin released nitrite when added to macrophage cultures. A maximum of 3.

Altered calcium homeostasis and membrane destabilization in erythrocytes of hamsters infected with Leishmania donovani.

Homeostatic mechanisms regulating intracellular concentrations of Ca2+ at a low level are prerequisites for maintaining the integral and cytoskeletal structure of erythrocytes under normal physiological conditions. The present study was undertaken to assess the contribution of Ca2+ homeostasis in modifying red-cell stability in hamsters, during the anaemia caused by Leishmania donovani. Erythrocytes from the infected animals became increasingly fragile as infection progressed.

Mutation of a unique aspartate residue abolishes the catalytic activity but not substrate binding of the mouse N-methylpurine-DNA glycosylase (MPG).

N-Methylpurine-DNA glycosylase (MPG) initiates base excision repair in DNA by removing a variety of alkylated purine adducts. Although Asp was identified as the active site residue in various DNA glycosylases based on the crystal structure, Glu-125 in human MPG (Glu-145 in mouse MPG) was recently proposed to be the catalytic residue. Mutational analysis for all Asp residues in a truncated, fully active MPG protein showed that only Asp-152 (Asp-132 in the human protein), which is located near the active site, is essential for catalytic activity.

The single amino acid changes in the yeast mitochondrial S4 ribosomal protein cause temperature-sensitive defect in the accumulation of mitochondrial 15S rRNA.

Four different mutant alleles of a nuclear gene (MNA6), which lose mt 15S rRNA at nonpermissive temperature (36 degrees C), were previously generated by EMS mutagenesis of Saccharomyces cerevisiae. To understand the biochemical basis for the loss of 15S rRNA in these mutants, the wild-type and mutant alleles of the MNA6 gene were isolated and characterized. The DNA sequencing of the cloned MNA6 gene revealed that it has an open reading frame specifying a 486 amino acid polypeptide, which appears to be a yeast mt homologue of the S4 r-protein family.

Chemical and pharmacological evaluation of different ayurvedic preparations of iron.

Ayurvedic preparations of metallic iron commonly categorised as different 'putas' of 'Louha Bhasma' was chemically analysed and pharmacologically investigated in iron deficiency anemia. Atomic absorption spectral (AAS) study of different putas of Louha Bhasma revealed the presence of various proportions of important metals along with varied concentration of iron in it. The effect of a representative puta viz.

Nucleotide sequences surrounding the nonanucleotide promoter motif influence the activity of yeast mitochondrial promoter.

The highly conserved nonanucleotide (5'-TATAAGTAA[+2]) promoter sequence dictates initiation of gene-specific transcription by the mitochondrial (mt) RNA polymerase in yeast mitochondria. However, transcriptional efficiency of the nonanucleotide promoter in different mt genes varies severalfold. To explore the regulatory role of the promoter-proximal template sequence in mt transcription, different deletion, nucleotide (nt) substitution, and tandem promoter constructs were analyzed under in vitro transcription reaction conditions.

Activation of human O6-methylguanine-DNA methyltransferase gene by glucocorticoid hormone.

O6-methylguanine-DNA methyltransferase (MGMT), a ubiquitous DNA repair protein, removes the mutagenic DNA adduct O6-alkylguanine, which is synthesized both endogenously and after exposure to alkylnitrosamines and alkylating antitumor drugs such as 2-chloroethyl-N-nitrosourea (CNU). The MGMT gene is highly regulated in mammalian cells and its overexpression, observed in many types of tumor cells, is often associated with cellular resistance to CNU. Dexamethasone, a synthetic glucocorticoid hormone, was found to increase MGMT expression in HeLa S3 cells, concomitant with their increased resistance to CNU.

Regulation of expression of the DNA repair gene O6-methylguanine-DNA methyltransferase via protein kinase C-mediated signaling.

O6-Alkylguanine is the major mutagenic and cytotoxic DNA lesion induced by alkylating agents, including 2-chloroethyl-N-nitrosourea-based antitumor drugs. This lesion is repaired by O6-methylguanine-DNA methyltransferase (MGMT), the expression of which is highly variable in both normal tissues and in tumor cells. The promoter of the human MGMT gene was found to contain two putative activator protein (AP)-1 sites.

Purification and characterization of human NTH1, a homolog of Escherichia coli endonuclease III. Direct identification of Lys-212 as the active nucleophilic residue.

The human endonuclease III (hNTH1), a homolog of the Escherichia coli enzyme (Nth), is a DNA glycosylase with abasic (apurinic/apyrimidinic (AP)) lyase activity and specifically cleaves oxidatively damaged pyrimidines in DNA. Its cDNA was cloned, and the full-length enzyme (304 amino acid residues) was expressed as a glutathione S-transferase fusion polypeptide in E. coli.

Usage of non-canonical promoter sequence by the yeast mitochondrial RNA polymerase.

Prior work has demonstrated that a conserved nonanucleotide [5'-TATAAGTAA(+2)] promoter sequence is used by the mitochondrial [mt]1 RNA polymerase in Saccharomyces cerevisiae. However, the highly AT-rich yeast mt genome carries many other promoter-like sequences, but only a fraction of them are involved in gene-specific transcription. To examine the sequence variability of this nonanucleotide promoter motif, single or multiple nt substitutions were introduced into the canonical promoter sequence.

Specific interaction of wild-type and truncated mouse N-methylpurine-DNA glycosylase with ethenoadenine-containing DNA.

N-Methylpurine-DNA glycosylase (MPG), a ubiquitous DNA repair enzyme, is responsible for the removal of a wide variety of alkylated base lesions in DNA, e.g., N-alkylpurines and cyclic ethenoadducts of adenine, guanine, and cytosine.

Position-specific inhibition of yeast mitochondrial transcription by a poly(T) sequence.

The 3' flanking nucleotide(s) of the octanucleotide promoter sequence regulates transcriptional efficiency of some mitochondrial genes in Saccharomyces cerevisiae. To understand this regulation the in vitro transcriptional activity of various synthetic mitochondrial promoters carrying different 3' flanking sequences was examined. The results presented here demonstrate that consecutive thymidine residues, but no other polynucleotides or secondary structure, in the promoter-proximal non-transcribed DNA strand inhibited mitochondrial transcription.

Specific recognition of O6-methylguanine in DNA by active site mutants of human O6-methylguanine-DNA methyltransferase.

O6-Methylguanine-DNA methyltransferase (MGMT), a ubiquitous DNA repair protein, acts as a monomer in removing the mutagenic DNA adduct O6-alkylguanine (induced by alkylating carcinogens) via a stoichiometric reaction. The alkyl group is transferred without a cofactor to a specific cysteine acceptor residue of MGMT, Cys-145 in the case of human MGMT, containing 207 amino acid residues and thereby inactivates the protein. As a prelude to the investigation of the reaction mechanism of human MGMT by elucidation of its structure in free and substrate-bound forms via NMR spectroscopy and X-ray crystallography, two types of MGMT mutants were generated and characterized.

Unusual usage of noncomplementary dinucleotide primers by the yeast mitochondrial RNA polymerase.

The mitochondrial RNase P RNA gene in yeast Saccharomyces cerevisiae is transcribed from a variant mitochondrial promoter (SP). The sequence of this SP promoter [TATAAGAAG (+2)] differs from the conserved mitochondrial promoter sequence [TATAAGTAA (+2)] by-1T-->A and +2A-->G nucleotide substitutions. To determine the effect of these nucleotide alterations in mitochondrial promoter function, an in vitro transcription analysis was carried out.

Lipid peroxidation of erythrocytes in visceral leishmaniasis.

Lipid peroxidation of erythrocytes was studied in kala-azar patients having a considerable degree of anemia. Enhanced formation of oxidative metabolic products was observed in the erythrocytes of these patients. Decreased activities of the protective enzymes suggest impairment of the defense mechanism against peroxidative threat.

Murine splenocyte proliferation by porin of Shigella dysenteriae type 1 and inhibition of bacterial invasion of HeLa cell by anti-porin antibody.

The purified porin of Shigella dysenteriae type 1 showed strong mitogenic activity for murine splenocytes. Preincubation of S. dysenteriae type 1 with anti-porin antibody reduced the bacterial plaque formation in HeLa cell monolayers by 45%.

Expression of the mitochondrial RNase P RNA subunit-encoding gene from a variant promoter sequence in Saccharomyces cerevisiae.

Ribonuclease P (RNase P) is a common tRNA processing enzyme that removes the 5' leader sequence of precursor tRNAs. This activity is identified in yeast mitochondria as a separate enzyme from the nuclear RNase P. Like other RNase P enzymes, the mitochondrial (mt) RNase P is also a ribonucleoprotein composed of both RNA and protein subunits.

Purification of acid phosphatase I from germinating seeds of Vigna sinensis.

Acid phosphatase I (AP-I) is the major isoform of Vigna acid phosphatase. It is constitutively expressed in seed cotyledons during germination. AP-I was separated from other isoforms and purified to homogeneity by three simple purification steps; (NH4)2SO4 precipitation, and phosphocellulose and DEAE-cellulose column chromatography.

Elevated 2,3-diphosphoglycerate concentrations and alteration of structural integrity in the erythrocytes of Indian cases of visceral leishmaniasis.

The visceral leishmaniasis (VL) known as kala-azar in India is characterized by severe anaemia. The anaemia seems to be the result, at least in part, of the relatively short life-time of the erythrocytes, which have weakened cell membranes, possibly because of elevated concentrations of 2,3-diphosphoglycerate (2,3-DPG). There is a negative correlation (r = 0.