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Biomedical subjects

K Christiansen

Publications and source records attributed to K Christiansen.

At least 109 records · Page 6Linked to original sources
PubMed1981

Systemic infection with Trichosporon cutaneum in a patient with acute leukemia: report of a case.

A case of disseminated infection with Trichosporon cutaneum, a fungus that causes white piedra, is described. The patient, a 58-year-old barber with acute leukemia, had fever, myalgias and skin lesions. He was receiving cytotoxic drug therapy and prednisone, was severely neutropenic and was being treated with broad spectrum antibiotics. Blood cultures and a biopsy of the skin lesion grew T. cutaneum. He died despite amphotericin B therapy. At autopsy, widespread infection with T. cutaneum was present. T. cutaneum is another fungus capable of causing widespread systemic disease in the immunocompromised host.

Amphotericin B↗
PubMed1981

Microvillus membrane vesicles from pig small intestine. Purity and lipid composition.

Microvillus membrane vesicles from pig small intestine were isolated by a method based on hypotonic lysis, Mg2+-aggregation of contaminants and differential centrifugation. The purity of the membrane vesicles were established by measuring the activity of marker enzymes and the RNA and DNA content. The membranes were found free of contamination by other subcellular membrane fragments, except for a minor contamination with basolateral plasma membranes. The lipid composition was established and, based on weight percentage, the membrane contained neutral lipids, phospholipids, neutral glycolipids and gangliosides in the weight ratio of 18 : 50 : 29 : 2%. The amount of individual phospholipids and glycolipids were quantitated. Phosphatidylethanolamine, -choline, -serine, -inositol and sphingomyelin made up 17, 17, 6, 5 and 5%, respectively of the total lipid. The major glycolipids were two monohexosylceramides containing glucose and galactose as the carbohydrate component, a dihexosylceramide containing galactose as the only carbohydrate component and two pentahexosylceramides containing fucose, galactose, glucose and hexosamine (either N-acetylglucosamine or N-acetylgalactosamine) in the molar ratio of 1 : 2 : 1 : 1.

Alkaline Phosphatase↗
PubMed1981

Reconstitution of purified amphiphilic pig intestinal microvillus aminopeptidase. Mode of membrane insertion and morphology.

Pig intestinal microvillus aminopeptidase (EC 3.4.11.2) was reincorporated into lipid membranes by using either beta-octyl glucoside or sodium deoxycholate. The results showed that for this enzyme the deoxycholate-dialysis method was the preferable one. By using this method, microvillus aminopeptidase was inserted almost quantitatively into either phosphatidylcholine vesicles or microvillus-lipid vesicles. By proteolytic treatment of the vesicles, by probing the aminopeptidase with an inhibitory antibody and by monitoring the positioning of the anchor with the aid of [125I]iodonaphthyl azide, it was demonstrated that the catalytically active part was located outside the liposomes and the anchoring peptide(2) was associated with the membrane. Electron-microscopic observation on this model system demonstrated a dimeric symmetrical structure of aminopeptidase (dimensions about 13.5 nm X 5.5 nm) separated by a 5 nm gap from the membrane. This distance corresponds to a molecular weight of 2000-5000 for this junctional segment of the anchor connecting the intramembrane part of the anchor with the catalytically active main part of the aminopeptidase.

Aminopeptidases↗
PubMed1980

Metal sensitivity causing loosened joint prostheses.

Metal sensitivity, as measured by an in-vitro assay on peripheral blood lymphocytes, was evaluated in patients with failed joint prostheses. Lymphocyte transformation to chromium, cobalt, and nickel was measured in 24 patients having revision surgery for a painful or loose prosthesis and compared with that in 11 patients who had a successful hip prothesis in situ for at least 2 years previously. A positive response (lymphocyte stimulation index greater than 3) to at least one of the metals was found in 71% of the revision group compared to 9% of controls (P < 0.01). The positive correlation between prosthesis failure and in-vitro metal sensitivity suggests that cell-mediated immunity to metals to metals may play a role in prosthesis failure. Furthermore, this simple in-vitro test may provide the basis of a useful diagnostic test for an often difficult clinical problem.

Aged↗
PubMed1979

Utilization of endogenous diacylglycerol for the synthesis of triacylglycerol, phosphatidylcholine and phosphatidylethanolamine by lipid particles from baker's yeast (Saccharomyces cerevisiae).

The activity of the enzymes diacylglycerol acyltransferase (EC 2.3.1.20), cholinephosphotransferase (EC 2.7.8.2) and ethanolaminephosphotransferase (EC 2.7.8.1) have been measured in a lipid particle preparation from baker's yeast (Saccharomyces cerevisiae) with endogenous 1,2-diacylglycerol as substrate. For all three enzymes the rate of diacylglycerol utilization was established with respect to substrate and Mg2+ concentration. Neither of the enzyme activities was stimulated significantly by addition of diacylglycerols. The conversion of diacylglycerol into triacylglycerol in the presence of CDP-choline and CDPethanolamine, and the synthesis of phospholipids in the presence of acyl-CoA either added or generated in situ were studied. Neither CDPcholine nor CDPethanolamine had an effect on triacylglycerol synthesis. Exogenous acyl-CoA had no effect on either choline- or ethanolaminephosphotransferase activity. However, when the necessary substrates for formation of acyl-CoAs in situ (ATP, CoA, Mg2+ and free fatty acids) were added a decrease in both cholinephosphotransferase and ethanolaminephosphotransferase activity was observed. This inhibition was shown to be due to ATP and might explained as a result of chelation of the Mg2+, a necessary activator of both the choline- and the ethanolaminephosphotransferase.

Acetyl Coenzyme A↗
PubMed1978

Triacylglycerol synthesis in lipid particles from baker's yeast (Saccharomyces cerevisiae).

Triacylglycerol synthesis has been studied in a lipid particle preparation of baker's yeast (Saccharomyces cerevisiae), and compared with the synthesis in other subcellular fractions. Fatty acid-CoA ligase (AMP) (EC 6.2.1.3) activity and sn-glycerol 3-phosphate acyltransferase activity (EC 2.3.1.15) were present in all the subcellular fractions tested but the highest specific activities of both enzymes were observed with the lipid particle fraction. The products of the glycerol 3-phosphate acylation indicate that triacyglycerol synthesis proceeds through the phosphatidic acid pathway. However, only a small and nearly constant amount of lysophosphatidic acid was found with the lipid particle fraction while the other subcellular fraction produced lysophosphatidic and phosphatidic acid with a more pronounced precursor/product relationship. Triacylglycerol synthesis from endogenous diacylglycerol present in the lipid particle was also demonstrated.

Acylation↗
PubMed1975

Membrane-bounded lipid particles from beef heart acylglycerol synthesis.

The site for the synthesis of triacylglycerol in heart muscle has been the subject of this study. Acyl-CoA synthetase and glycerophosphate acyltransferase, enzymest necessary for the synthesis of triacylglycerol, have been found to be associated to membrane-bounded lipid particles. The acylglycerol synthesizing enzymes exhibit higher activities in the membrane-bounded lipid particles than in the mitochondrial or microsomal fractions. Futhermore, the lipid particles have the greater capacity for synthesis of diacylglycerols and triacylglycerols, whereas monoacylgly cerols are the major neutral lipid product in both the mitochondrial and the microsomal fractions. The results indicate that the membrane-bounded lipid particle may be the site for the synthesis as well as for the storage of intracellular triacylglycerol of the heart.

Animals↗
PubMed1968

Improved method for the preparation of malonyl coenzyme A.

Malonyl coenzyme A is synthesized by transacylating S-malonyl-N-decanoyl cysteamine with coenzyme A. A simplified procedure for the preparation of S-malonyl-N-decanoyl cysteamine, using cysteamine as starting material, is described.

Coenzyme A↗