Interaction of silicate dust with erythrocyte ghost membrane: in vitro studies

Composition of the erythrocyte ghost membrane obtained from slate-dust-lysed and hypotonically lysed erythrocytes were compared in vitro. The protein and cholesterol contents were unaltered, whilst phospholipid and glycosamine contents decreased significantly in the slate-dust-lysed preparation of erythrocyte ghost membrane. Na+, K+-ATPase activity remained unchanged, whilst acetylcholinesterase activity was decreased slightly by slate dust treatment. Further, binding of silicic acid, dissolving out of slate dust, was observed with a component of erythrocyte ghost membrane protein having molecular weight around 90 000 daltons. The significance of the findings is discussed.

Aldose and aldehyde reductases in human tissues

Immunochemical characterizations of aldose reductase and aldehyde reductases I and II, partially purified by DEAE-cellulose (DE-52) column chromatography from human tissues, were carried out by immunotitration, using antisera raised against the homogenous preparations of human and bovine lens aldose reductase and human placenta aldehyde reductase I and aldehyde reductase II. Anti-aldose antiserum cross-reacted with aldehyde reductase I, anti-aldehyde reductase I antiserum cross-reacted with aldose reductase and anti-aldehyde reductase II antiserum precipitated aldehyde reductase II, but did not cross-react with aldose reductase or aldehyde reductase I from all the tissues examined. DE-52 elution profiles, substrate specificity and immunochemical characterization indicate that aldose reductase is present in human aorta, brain, erythrocyte and muscle; aldehyde reductase I is present in human kidney, liver and placenta; and aldehyde reductase II is present in human brain, erythrocyte, kidney, liver, lung and placenta. Monospecific anti-alpha and anti-beta antisera were purified from placenta anti-aldehyde reductase I antiserum, using immunoaffinity techniques. Anti-alpha antiserum precipitated both aldehyde reductase I and aldose reductase, whereas anti-beta antibodies cross-reacted with only aldehyde reductase I. Based on these studies, a three gene loci model is proposed to explain the genetic interrelationships among these enzymes. Aldose reductase is a monomer of alpha subunits, aldehyde reductase I is a dimer of alpha and beta subunits and aldehyde reductase II is a monomer of delta subunits.

The binding of silica to proteins from plasma and lungs of rat: in vitro

Silica dissolving out from the slate dust was found to bind with plasma protein and purified bovine serum albumin. At 24 h of incubation at 37 degrees C binding affinity of silica (microgram of silica bound/mg of protein) with plasma protein and bovine serum albumin was found to be 0.59 and 0.44, respectively. By molecular exclusion chromatography using Sephadex G-200, silica binding protein of plasma was determined to be of mol. wt. around 67000. Similar proteins having silica binding capacity (mol. wt. 70000 and 85000) were also found in rat lung but these proteins unlike their plasma counterpart were glycoprotein in nature. Polyacrylamide gel electrophoresis of plasma and protein rich lung fraction show that proteins upon binding with silica undergo mobility changes. Significance of the existence of silica binding protein in plasma and lung of rat in relation to silica toxicity is discussed.

Biochemical studies on the toxicity of hematite dust

Biochemical alterations in guinea pig lungs caused by hematite dust were followed at 150 days after intratracheal administration of the dust. In vivo dust exposure caused a significant increase in mitochondrial protein content and cytochrome c oxidase activity whereas diaphorase activity remained unaltered. Mitochondria from the exposed animals were apparently in a swollen state and their contraction profile upon the addition of ATP reflected permeability changes. However, in vitro dust caused no significant alterations. Significant increases in glycogen content along with an insignificant decrease in glycogen phosphorylase activity were also observed in hematite-treated guinea pig lungs. Decrease in drug-metabolizing enzymes such as aniline hydroxylase and tyrosine aminotransferase activities were also evident in the postmitochondrial fraction of the siderotic lungs. [3H]Leucine-incorporation studies showed increased protein synthesis in the postmitochondrial fraction. Increase in protein synthesis in mitochondria was only marginal whereas in whole homogenate it decreased considerably. Experiments employing dust tagged with radioactive iron indicated the rapid mobilization of iron from lung and its distribution to various organs. The presence of iron-binding protein was confirmed by employing Sephadex gel-filtration techniques.

Biochemical mechanisms in asbestos toxicity

The alarming hazardous nature of asbestos makes it the foremost among toxic fugitive dusts. The biochemical mechanisms responsible for the diverse biological effects of asbestos, such as fibrosis, asbestos bodies, pleural plaques, respiratory difficulty, cancer, and cytotoxicity, are being studied in this laboratory. As asbestosis progresses in guinea pigs, along with reticulum formation, lysosomal enzymes are released from membrane-bound latent state to active free form, initiating degradative changes. Considerable alterations take place in the pulmonary metabolic machinery. Mitochondria in lung cells were found to be important loci for the toxic effect of asbestos. A profile of mitochondrial activity, in control and asbestotic animals, revealed specific enzymic changes such as increased cytochrome c oxidase during the disease. The functional organization of mitochondria was also altered, since the organelles from asbestotic lungs were swollen as measured by spectrophotometry. Glutamate dehydrogenase activity of mitochondria became exposed in asbestosis. The maleate dehydrogenase shunt which is involved in transport of the redox potential across the membrane was enhanced in cytosol and mitochondria. The involvement of microsomal enzymes in asbestosis was indicated by alterations in glucose-6-phosphatase and tyrosine transaminase and aniline hydroxylase. Changes in the biotransformational capacity of lung, due to asbestos, could be an important aspect in toxicity, especially the carcinogenic effect. Considerable alterations were encountered in the levels of different phospholipids and in mucopolysaccharide constituents. On the basis of the above, the molecular mechanisms in asbestos toxicity are explained as an integrated model. Interactions of dust constituents with those of membranes and the ensuing metabolic adjustments are thus important in the etiology of asbestosis.

Lung mitochondria in experimental asbestosis

Alterations in lung mitochondria were followed in guinea pigs at different periods after a single intratracheal injection of chrysotile dust. Cytochrome c oxidase and succinic dehydrogenase activities showed gradual increase after 90 days, whereas monoamine oxidase remained unaffected throughout the study. There was an increase in glutamate dehydrogenase activity in postmitochondrial as well as in mitochondrial fractions, the latter being accompanied by decreased latency of the enzyme. Mitochondria from asbestotic lung appeared to be more swollen than in normal animals at and after 90 days of exposure. There were fluctuations in the contents of different phospholipids as a result of asbestosis. Beyond 90 days, collagen and mucopolysaccharides also increased. The results confirm the contention that pulmonary mitochondria are among the major target sites in asbestosis.

Relationship between solubility and hemolytic effects of toxic dusts

Two varieties of native and chemically treated slate dust were tested in vitro for their hemolytic effects and the extent of silicic acid dissolution in various physiological fluids. The extent of hemolysis was found to be proportional to the degree of dissolution of dust constituents. Membrane lysis by the dust appeared to be prevented by coating it with polyvinyl pyrrolidone, serum proteins and pulmonary lavage lipids. The significance of the findings is discussed.

Pesticide (hexachlorocyclohexane) inhibition of growth and nitrogen fixation in blue-green algae Anabaenopsis raciborskii and Anabaena aphanizomenoides

The effects of the pesticide hexachlorocyclohexane (HCH) on the nitrogen fixing blue-green algae Anabaenopsis raciborskii and Anabaena aphanizomenoides commonly found as blooms in fish ponds were studied. These algae were very sensitive to HCH, and a distinct decrease in growth rate was observed on prolonged incubation. Lower concentrations (10 microgram/ml) were algistatic and higher concentrations (60 microgram/ml) were algicidal. The inhibition of nitrogen fixation indicated that the presence of HCH might affect overall nitrogen economy of inland waters.

Synergistic effects of hydralazine and alpha- or beta-adrenergic blockers: the role of plasma renin activity

Intravenous hydralazine, 0.15, 0.30 or 0.60 mg/kg, was administered to 11 supine hypertensives on two occasions: once after pretreatment with intravenous propranolol, 0.1 mg/kg, and once after pretreatment with intravenous placebo. The average fall in mean arterial pressure for each dosage of hydralazine was no different with or without propranolol, even though propranolol inhibited rises in plasma renin activity and pulse due to hydralazine. However, in each of four patients who had high supine baseline plasma renin activity, propranolol enhanced the fall in blood pressure caused by hydralazine. A second group of patients was given an infusion of 0.01 or 0.02 mg/kg per minute phentolamine, which did not change baseline blood pressure. Subsequent administration of intravenous hydralazine, 0.15 mg/kg, resulted in a fall in blood pressure which was larger than previously observed with intravenous hydralazine alone, regardless of supine baseline plasma renin activity. These data are consistent with the hypothesis that reflex catecholamine release interferes with the hypotensive effect of intravenous hydralazine. Pretreating with propranolol weakens homeostatic defenses against hydralazine such as rises in pulse rate and plasma renin activity. However, propranolol appears to enhance the alpha-adrenergic effect of released catecholamines, and the antihypertensive response to hydralazine is unaltered. In patients with high supine plasma renin activity, propranolol potentiates the fall in blood pressure induced by hydralazine, perhaps because the hypertension in such patients is renin dependent.

Controlled trial of the effect of cycloalliin on the fibrinolytic activity of venous blood

Cycloalliin is a natural constituent of onion, sulphur-containing but odourless. It was synthesised for this randomised double-blind study; its effect on fibribolytic activity and platelet aggregability was tested in venous blood from 18 male volunteers. It increased the former to a highly significant degree but had no effect on the latter. It was well tolerated and harmless in the single oral dosage used.

[Determination of the primary structure of alfalfa mosaic virus (strain S) coat protein. II. Complete sequence of the protein (author's transl)]

The alfalfa mosaic virus protein was submitted to the action of cyanogen bromide. Four peptides were isolated. Study of these peptides allowed us to determine the order. Then protein was submitted, after S-carboxymethylation or S-aminoethylation, to the action of different proteolytic enzymes: trypsin, chymotrypsin, thermolysin and papain. The peptides issued from these different hydrolysis were separated on Dowex 50 X4 and Dowex 1 X2, and their amino acid composition was determined. The use of classical methods of sequence determination, of mass spectrometry and for one case the use of a sequencer, lead to the obtention of the primary structure of all the tryptic peptides. The studies of chymotryptic, thermolytic and papainic hydrolysates, and of cyanogen bromide rupture, allowed us to isolate the overlapping peptides which were necessary for the reconstitution of the complete proteic chain.

Intrahepatic arterial infusion of combination of mitomycin-C and 5-fluorouracil in treatment of primary and metastatic liver carcinoma

Improvement in drug response and reduction of toxicity were observed after continuous intrahepatic arterial infusion of mytomycin-C (MMC) and 5-fluorouracil (5-FU) in 15 of 26 patients with primary or metastatic carcinoma of the liver. Serum bilirubin values of 10 mg/100 ml absence of ascites, extreme cachexia and impending hepatic failure were used as the criteria for admission of these patients into the study. The patients were given MMC in a dose of 0.08 mg/kg on day 1,5-FU in a dose of 8-10 mg/kg on days 2-5, and MMC on day 6. This schedule was reinitiated on days 8 and 15 for total mean duration of 18 days. Maintenance therapy was carried out by the administration of these drugs at induction dosage alternated each week as a single 24 hourly intravenous infusion. Objective response to combination therapy was defined as decrease of at least 50% in the liver size and in the abnormal levels of serum alkaline phosphatase and glutamic oxaloacetic transaminase (SGOT), and near normal levels of serum bilirubin for a minimum period of 2 months. The duration of objective response ranged from 3-16 months with a median of 8.2 months. The median survival time for the responders was 7.2 months for patients with primary carcinoma and 9.4 months for patients with metastatic carcinoma of the liver as compared to 2 months for patients who failed to respond to the treatment. Five out of 12 patients who were refractory to MMC or 5-FU by intravenous infusion responded to the present combination drug therapy. Of four patients who died during induction therapy, three had liver failure and the fourth suffered pulmonary embolism. These studies provide evidence that combination therapy with MMC and 5-FU increases the survival time of patients with hepatic cancer, presumably due to the synergistic action of these drugs which permits the use of a low dosage schedule and has less toxic effects.

Intrahepatic arterial infusion of combination of mitomycin-C and 5-fluorouracil in treatment of primary and metastatic liver carcinoma

Improvement in drug response and reduction of toxicity were observed after continuous intrahepatic arterial infusion of mytomycin-C (MMC) and 5-fluorouracil (5-FU) in 15 of 26 patients with primary or metastatic carcinoma of the liver. Serum bilirubin values of 10 mg/100 ml absence of ascites, extreme cachexia and impending hepatic failure were used as the criteria for admission of these patients into the study. The patients were given MMC in a dose of 0.08 mg/kg on day 1,5-FU in a dose of 8-10 mg/kg on days 2-5, and MMC on day 6. This schedule was reinitiated on days 8 and 15 for total mean duration of 18 days. Maintenance therapy was carried out by the administration of these drugs at induction dosage alternated each week as a single 24 hourly intravenous infusion. Objective response to combination therapy was defined as decrease of at least 50% in the liver size and in the abnormal levels of serum alkaline phosphatase and glutamic oxaloacetic transaminase (SGOT), and near normal levels of serum bilirubin for a minimum period of 2 months. The duration of objective response ranged from 3-16 months with a median of 8.2 months. The median survival time for the responders was 7.2 months for patients with primary carcinoma and 9.4 months for patients with metastatic carcinoma of the liver as compared to 2 months for patients who failed to respond to the treatment. Five out of 12 patients who were refractory to MMC or 5-FU by intravenous infusion responded to the present combination drug therapy. Of four patients who died during induction therapy, three had liver failure and the fourth suffered pulmonary embolism. These studies provide evidence that combination therapy with MMC and 5-FU increases the survival time of patients with hepatic cancer, presumably due to the synergistic action of these drugs which permits the use of a low dosage schedule and has less toxic effects.

Carbon dioxide homeostasis during laparoscopy

Arterial blood gases were monitored in ten patients undergoing laparoscopy for diagnostic or sterilization procedure. During constant volume of ventilation, mean arterial co2 tension rose approximately 5 torr following insufflation of the peritoneal cavity with carbon dioxide. Arterial pH changes correlated well with arterial Pco2 changes. There was no significant change of oxygen tension in these patients.

Variability in structural carbohydrates and in vitro digestibility of forages. 3. Guar (Cyamopsis tetragonoloba)

Thirteen genotypes of guar (Cyamopsis tetragonoloba) were compared with the local variety for structural carbohydrates and in vitro digestibility. Neutral detergent fiber, acid detergent fiber, lignin, and acid insoluble ash varied 31.2 to 44.4, 26.1 to 37.4, 6.8 to 11.1, and .30 to 1.11%. Cellulose varied from 16.6 to 28.1% whereas hemicellulose content ranged between 3.6 and 9.2%. In vitro digestibility of dry matter ranged between 62.8 to 71.2% Variation in protein, mineral matter, and percentage of dry matter was from 12.7 to 19.7, 9.4 to 12.3, and 23.0 to 26.7. Neutral detergent fiber and lignin plus silica were correlated negatively with in vitro digestibility of dry matter. A genetic manipulation of breeding material can bring about a highly nutritive genotype of guar.

Clinical and Bacteriological Profiles of Blood Culture Positive Sepsis in Newborns

Neonatal infections currently cause about 1.6 million deaths annually in developing countries. Sepsis and meningitis is responsible for most of these deaths. This study was undertaken to determine the clinical presentations, bacteriological profiles and antibiotic sensitivity patterns of isolates from blood cultures of neonates admitted in a tertiary care hospital in Eastern Nepal. All blood culture reports (n=103) during January 2006 - February 2007 from newborns admitted in neonatal division at BP Koirala Institute of Health Sciences, Nepal were analyzed and antibiotic sensitivity patterns were studied. The positive blood culture was 20% (103/513). Most (97.1%) of the sepsis was caused by single organism, while polymicrobial aetiology was observed in 2.9% cases. Meningitis was documented in 9(8.7%) cases. Staphylococcus aureus (38.8%) and coagulase negative staphylococcus (CONS) (21.3%) are the commonest isolates in blood culture. Among gram-negative organisms, Klebsiella species (11.6%) and Enterobacter species (9.7%) were the leading cause of neonatal sepsis. Majority of newborns with neonatal sepsis presented with refusal to feeds (42.7%), fever (41.7%) and jaundice (41.7%). Most of the organisms showed sensitivity with amino glycosides (gentamicin and amikacin) and third generation cephalosporins. It is concluded that Staphylococcus aureus, CONS, and Klebsiella species remain the principal organisms causing neonatal sepsis and first line antibiotics like amino glycosides should be first choice of drugs. Key words: Blood culture, neonatal sepsis, antibiotic sensitivity. doi:10.3126/jnps.v27i2.1411   J. Nepal Paediatr. Soc. Vol.27(2) p.64-67