Lysis of zoopathogenic fungi by streptomycetes

The cell walls of the yeast cell phases of Histoplasma capsulatum, Blastomyces dermatitidis, and Sporothrix schenckii were lysed by enzymes formed during the growth of Streptomyces spp. Mycelial elements of H. capsulatum were not lysed by the streptomycetes.

Comparative physiologial studies of the yeast and mycelial forms of Histoplasma capsulaum: uptake and incorporation of L-leucine

l-Leucine entered the cells of both morphological forms of Histoplasma capsulatum by a permease-like system at low external concentrations of substrate. However, at levels greater than 5 x 10(-5)m l-leucine, the amino acid entered the cells both through a simple diffusion-like process and the permease-like system. The rate of the amino acid diffusion into yeast and mycelial forms appeared to be the same, whereas the initial rate of accumulation through the permease-like system was 5 to 10 times faster in the mycelial phase than it was in the yeast phase. The Michaelis constants were 2.2 x 10(-5)m in yeast phase and 2 x 10(-5)m in mycelial phase cells. Transport of l-leucine at an external concentration of 10(-5)m showed all of the characteristics of a system of active transport, which was dependent on temperature and pH. Displacement or removal of the alpha-amino group, or modification of the alpha-carboxyl group abolished amino acid uptake. The process was competitively inhibited by neutral aliphatic side-chain amino acids (inhibition constants ranged from 1.5 x 10(-5) to 6.2 x 10(-5)m). Neutral aromatic side-chain amino acids and the d-isomers of leucine and valine did not inhibit l-leucine uptake. These data were interpreted to mean that the l-leucine transport system is stereospecific and is highly specific for neutral aliphatic side-chain amino acids. Incorporation of l-leucine into macromolecules occurred at almost the same rate in both morphological forms of the fungus. The mycelial phase but not the yeast phase showed a slight initial lag in incorporation. In both morphological forms the intracellular pool of l-leucine was of limited capacity, and the total uptake of the amino acid was a function of intracellular pool size. The initial rate of l-leucine uptake was independent of the level of intracellular pool. Both morphological forms deaminated and degraded only a minor fraction of the accumulated leucine.

Double nuclear magnetic resonance observation of electron exchange between ferri- and ferrocytochrome c

Cyanide-inhibited electron exchange between ferri- and ferrocytochrome c molecules has been observed by nuclear magnetic resonance. Irradiation of a partially reduced protein solution at resonance frequencies arising from protons of the oxidized state results in a decrease in the absorption due to the corresponding protons of the reduced state. The experiment quantitates the hyperfine shifts observed in this system and can be used to identify hitherto unassignable resonances. Analysis of the shifts suggests that an aromatic side chain ring lies near the edge of the heme ring.

Amino acid transport by the filamentous fungus Arthrobotrys conoides

Uptake of l-valine by germinated spores of Arthrobotrys conoides has all the characteristics of a system of transport that requires an expenditure of energy by the cells. It is dependent on temperature and has an energy of activation of 16,000 cal/mole. Uptake is optimal at pH 5 to 6. l-Valine accumulated against a concentration gradient and is not lost from the cells by leakage or exchange. The process requires energy supplied by the metabolic reactions that are inhibited by catalytic amounts of 2,4-dinitrophenol and azide. The kinetics of the system are consistent with a mechanism of transport that depends on a limited number of sites on the cell surface, and the Michaelis constant for the system is 1.5 x 10(-5) to 7.5 x 10(-5)m. Modification of the amino or carboxyl group abolishes l-valine uptake. The process is competitively inhibited by d-valine, glycine, and other neutral amino acids (K(i) = 1.5 x 10(-5) to 4.0 x 10(-5)m), indicating a lack of stereospecificity, and also indicating that aliphatic side chain is not required for binding with the carrier. The transport system has less affinity for acidic amino acids (glutamic and aspartic acids) than neutral amino acids, and a greater affinity for basic amino acids (histidine, lysine, and arginine). The range of affinity is in the order of 100, as measured in terms of K(i) values for various compounds. The data presented provide suggestive evidence that the uptake by A. conoides of all amino acids except proline is mediated by a single carrier system that possesses an overall negative charge.

Metabolism of valine by the filamentous fungus Arthrobotrys conoides

Uptake of valine by Arthrobotrys conoides was an active process and was independent of its incorporation into cellular protein. Chemical fractionation of cells supplied with (14)C-l-valine for different time intervals revealed that the amino acid initially entered a pool of metabolic intermediates and was extractable with cold trichloroacetic acid. After a 4-min interval, some intracellular valine was incorporated into cell proteins, but most underwent metabolic transformation to a variety of products that included carboxylic acids and other amino acids. Carbon derived from valine was not localized in the lipid or nucleic acid fraction of cells, but some was completely oxidized and recovered as metabolic (14)CO(2). Autoradiograms of paper and thin-layer chromatograms of acid hydrolysates of cellular protein identified the following amino acids as having originated from valine: glutamate, aspartate, alanine, and leucine. Similar analysis of cold trichloroacetic acid extracts established that (14)C supplied as l-valine had been transformed also to alpha-ketoisovalerate, isobutyrate, propionate, succinate, malate, oxalacetate, pyruvate, and alpha-ketoglutarate. Pathways for transformation of the carbon skeleton of valine to various metabolic products are proposed.

A comparative study of early vs. delayed laparoscopic cholecystectomy in acute cholecystitis

Aims and Objectives: To compare the outcome in early vs. delayed laparoscopic cholecystectomy in terms of frequency of intra-operative and postoperative complications and to determine the rate and reasons for conversion. Materials and methods: A prospective randomized clinical trial was performed in the Department of Surgery at BP Koirala Institute of Health Sciences from February 2003 to June 2004 in all patients with the diagnosis of acute calculus cholecystitis. Results: Out of 145 cases, 50 cases were included in our study where 12 (24%) patients were males and 38 (76%) were females (M:F=1:3.16). The mean (SD) age of patients in early and delayed groups were 42.68 yrs. (14.18) and 40.26 yrs. (11.62) respectively. The mean (SD) duration of symptoms in early successful and converted groups were 109.24 hrs. (43.66) and 132 hrs. (49.96) respectively and the mean (SD) duration of symptoms in delayed successful and converted groups were 15.36 months (13.88) and 41 months (40.73) respectively. In early group, 17 (68%) patients had total leukocyte count more than 10,000/cmm and they had ultrasound findings suggestive of acute cholecystitis. Out of 25 patients in early group, seven had jaundice and ten had deranged liver function in the preoperative period. In early group 4 (16%) patients; and in delayed group 3 (12%) had to be converted to open cholecystectomy (P=1.00). In early group 10 (40%) and in delayed 5 (20 %) cases had intra-operative complications (P=0.122). The total hospital stay was longer in the delayed group. The postoperative hospital stay in early and delayed converted groups were higher than early and delayed successful group (P=0.081, P=0.082). Conclusion: Both early and delayed laparoscopic cholecystectomy is possible and safe in the treatment of acute cholecystitis. Key words: Acute cholecystitis, Laparoscopic cholecystectomy, Conversion doi: 10.3126/kumj.v7i1.1759       Kathmandu University Medical Journal (2009), Vol. 7, No. 1, Issue 25, 16-20