Mice Lacking Platelet-Derived Growth Factor D Display a Mild Vascular Phenotype

Platelet-derived growth factor D (PDGF-D) is the most recently discovered member of the PDGF family. PDGF-D signals through PDGF receptor β, but its biological role remains largely unknown. In contrast to other members of the PDGF family of growth factors, which have been extensively investigated using different knockout approaches in mice, PDGF-D has until now not been characterized by gene inactivation in mice. Here, we present the phenotype of a constitutive Pdgfd knockout mouse model (Pdgfd^-/-), carrying a LacZ reporter used to visualize Pdgfd promoter activity. Inactivation of the Pdgfd gene resulted in a mild phenotype in C57BL/6 mice, and the offspring was viable, fertile and generally in good health. We show that Pdgfd reporter gene activity was consistently localized to vascular structures in both postnatal and adult tissues. The expression was predominantly arterial, often localizing to vascular bifurcations. Endothelial cells appeared to be the dominating source for Pdgfd, but reporter gene activity was occasionally also found in subpopulations of mural cells. Tissue-specific analyses of vascular structures revealed that NG2-expressing pericytes of the cardiac vasculature were disorganized in Pdgfd^-/- mice. Furthermore, Pdgfd^-/- mice also had a slightly elevated blood pressure. In summary, the vascular expression pattern together with morphological changes in NG2-expressing cells, and the increase in blood pressure, support a function for PDGF-D in regulating systemic arterial blood pressure, and suggests a role in maintaining vascular homeostasis.     

Mercury in blood cells—Altered elemental profiles

The study was composed of 27 persons that displayed vague symptoms similar to those of the victims of Minamata and Iraq. Skew distributions of mercury were observed in individual erythrocytes and neutrophil granulocytes when measured by PIXE. Mercury could not be detected in the platelets. The erythrocytes also displayed lowered concentrations of magnesium and zinc, together with increased concentrations of calcium and strontium. The neutrophils displayed decreased concentrations of magnesium and zinc and increased concentrations of calcium, strontium, and iron. The presence of mercury and the altered elemental profiles in the erythrocytes and the neutrophil granulocytes are suggested as early signs of exposure.     

Transformation of Penicillium chrysogenum by a vector containing a mitochondrial origin of replication

Summary In order to establish a transformation system for P. chrysogenum autonomously replicating vectors were constructed using mitochondrial DNA sequences from the fungus. A physical map of the mt DNA of a production strain was established using ten different restriction enzymes. Unexpectedly, the mt DNA of this strain proved to be significantly smaller than that of a second strain from a culture collection (27 kb versus 49 kb). Various fragments representing about 71% of the 27 kb mt DNA were cloned and, at first, preselected for replicating activity in an intermediate host (Saccharomyces cerevisiae). Two of these fragments also promoted autonomous replication in P. chrysogenum, which was confirmed by isolation of bulk DNA and transfer into E. coli. For selection of transformants in P. chrysogenum the prokaryotic kanamycin resistance gene was used which increased about twofold the resistance against G418. Present address: Institut für Biotechnologie, Fachgebiet Mikrobiologie, Techn. Universität Berlin, Seestr. 13, D-1000 Berlin 65     

Cholesteryl ester transfer protein is secreted by Hep G2 cells and contains asparagine-linked carbohydrate and sialic acid

A cholesteryl ester transfer protein (CETP) of apparent Mr 74,000 has recently been purified from human plasma. Cholesteryl ester transfer activity was found to accumulate in the medium of cultured Hep G2 cells. The transfer activity was removed by immunoprecipitation with specific antibodies to the plasma CETP. Sodium dodecyl sulfate gel electrophoresis of immunoprecipitates prepared from the medium of cells pulsed with [35S]methionine revealed a broad specific band of protein of Mr 72,000 to 76,000; by contrast, immunoprecipitates of cellular homogenates showed a sharp specific band of Mr 58,000. The Mr 72,000 to 76,000 band disappears, concomitant with the appearance of lower Mr products, upon neuraminidase or glycopeptidase F treatment of medium immunoprecipitates or of purified CETP. The results indicate that liver cells have the capacity to synthesize and secrete CETP. The CETP peptide acquires asparagine-linked carbohydrate and sialic acid during intracellular processing.     

N-Deacetylation of 2-acetamido-2-deoxy-hexosecontaining oligosaccharides and polysaccharides by calcium in liquid ammonia

N-Deacetylation of 2-acetamido-2-deoxy-hexose residues is accomplished in liquid ammonia containing calcium. Oligosaccharides, lacto-N-fucopentaose II and lacto-N-difucohexaose I, containing 3,4-disubstitutedN-acetylhexosamine residues are quantitativelyN-deacetylated. When applied to polysaccharides, however, only partialN-deacetylation was achieved.Author for correspondence. AXRD     

Determination of the serological sex-specific (Sxs) antigen (“H-Y antigen”) in birds and mammals using high-titer antisera and a sensitive urease ELISA

Summary A rapid, sensitive, and reproducible enzyme-linked immunosorbent assay (ELISA), for the detection of the serological sex-specific (Sxs) antigen (formerly termed H-Y antigen; see Introduction), is described. This assay uses bovine lestes extract as the solid phase antigen, and high-titer anti-Sxs antisera and a urease-conjugated anti rat-IgG as the first and second antibody respectively. The urea containing substrate causes a pH shift in a positive reaction, which in turn is visualized by the use of bromocresol purple as a pH indicator. The method, and some representative applications of it, are described in detail.     

Effect of structured lipid-enriched total parenteral nutrition in rats bearing yoshida sarcoma

The efficacy of structured lipid, a triacylglycerol of medium and long chain fatty acids, as an element of nutritional support therapies in cancer cachexia was investigated. Using the Yoshida sarcoma to induce cachexia, male Sprague Dawley rats (90 g) were injected subcutaneously with tumor cells (n = 17) or sterile saline (n = 16). Seven days later, rats were randomized to two intravenous diets for 3 days at 220 kcal/kg body weight/d, including 2 g nitrogen/kg body weight/d and 39% of total calories as either structured lipid or long chain triglyceride. Nitrogen balance, tumor growth rate, energy metabolism, and plasma albumin and free fatty acid levels were measured, and whole-body protein kinetics and liver, muscle, and tumor fractional protein synthetic rates were evaluated by adding (14)C-leucine to the diet during the last 4 hours of feeding. Nitrogen balance improved (P < .05) in both tumor and control rats receiving structured lipid-enriched total parenteral nutrition, and was also greater in tumor rats compared with controls. There were no differences in tumor growth or protein kinetics between diet groups. Albumin was lower (P < .05) in tumor rats, but significantly higher in both tumor and control rats given structured lipid-enriched total parenteral nutrition. Free fatty acid was significantly higher in tumor rats versus controls. Whole-body protein kinetics were similar among the four groups. Liver weight, liver weight to body weight ratio, and liver protein synthetic rate were higher in tumor rats. Also, liver weight to body weight ratio was lower in tumor and control animals given structured lipid-enriched total parenteral nutrition. Muscle protein synthetic rate was significantly lower in tumor rats, but higher in tumor and control rats given long chain triglyceride-enriched total parenteral nutrition. The nutritional benefits of structured lipid-enriched total parenteral nutrition favor support of host tissue without promoting tumor growth.