APOE in non-Alzheimer amyloidoses: transmissible spongiform encephalopathies

We have identified a member of the VEGF family by computer-based homology searching and have designated it VEGF-D. VEGF-D is most closely related to VEGF-C by virtue of the presence of N- and C-terminal extensions that are not found in other VEGF family members. In adult human tissues, VEGF-D mRNA is most abundant in heart, lung, skeletal muscle, colon, and small intestine. Analyses of VEGF-D receptor specificity revealed that VEGF-D is a ligand for both VEGF receptors (VEGFRs) VEGFR-2 (Flk1) and VEGFR-3 (Flt4) and can activate these receptors. However. VEGF-D does not bind to VEGFR-1. Expression of a truncated derivative of VEGF-D demonstrated that the receptor-binding capacities reside in the portion of the molecule that is most closely related in primary structure to other VEGF family members and that corresponds to the mature form of VEGF-C. In addition, VEGF-D is a mitogen for endothelial cells. The structural and functional similarities between VEGF-D and VEGF-C define a subfamily of the VEGFs.     

The impact of treatment time and smoking on local control and complications in T1 glottic cancer

Low frequency impedance measurements of pure egg lecithin (phosphatidylcholine) bilayers have revealed the presence of four layers which can be attributed to the acyl chain, carbonyl, glycerol bridge and phosphatidylcholine regions of the lecithin molecule. Measurements on bilayers formed in the presence of unoxidised-cholesterol revealed that cholesterol molecules were located in the hydrocarbon region of the bilayer with its hydroxyl groups aligned with the carbonyl region of the lecithin molecules. Measurements of oxidised-cholesterol lecithin bilayers revealed that these molecules protruded less into the hydrocarbon region and their polar hydroxyl group aligned with the glycerol bridge region of the lecithin molecule.     

Uric acid, a natural scavenger of peroxynitrite, in experimental allergic encephalomyelitis and multiple sclerosis

Uric acid, the naturally occurring product of purine metabolism, is a strong peroxynitrite scavenger, as demonstrated by the capacity to bind peroxynitrite but not nitric oxide (NO) produced by lipopolysaccharide-stimulated cells of a mouse monocyte line. In this study, we used uric acid to treat experimental allergic encephalomyelitis (EAE) in the PLSJL strain of mice, which develop a chronic form of the disease with remissions and exacerbations. Uric acid administration was found to have strong therapeutic effects in a dose-dependent fashion. A regimen of four daily doses of 500 mg/kg uric acid was required to promote long-term survival regardless of whether treatment was initiated before or after the clinical symptoms of EAE had appeared. The requirement for multiple doses is likely to be caused by the rapid clearance of uric acid in mice which, unlike humans, metabolize uric acid a step further to allantoin. Uric acid treatment also was found to diminish clinical signs of a disease resembling EAE in interferon-gamma receptor knockout mice. A possible association between multiple sclerosis (MS), the disease on which EAE is modeled, and uric acid is supported by the finding that patients with MS have significantly lower levels of serum uric acid than controls. In addition, statistical evaluation of more than 20 million patient records for the incidence of MS and gout (hyperuricemic) revealed that the two diseases are almost mutually exclusive, raising the possibility that hyperuricemia may protect against MS.     

Independent origin of multiple foci of prostatic intraepithelial neoplasia: comparison with matched foci of prostate carcinoma

BACKGROUND: Prostate carcinoma usually is heterogeneous and multifocal, with diverse clinical and morphologic manifestations. Understanding of the molecular basis for this heterogeneity is limited, particularly for the putative precursor, high grade prostatic intraepithelial neoplasia (PIN). In this study, the authors attempted to determine the genetic relation between multiple foci of PIN and matched foci of carcinoma, and whether they are independent in origin. METHODS: The distribution and prevalence of allelic imbalance at 6 microsatellite polymorphic markers on chromosomes 7q, 8p, 8q, and 18q were examined in 84 microscopically excised PIN foci (mean, 1.6 foci/case) and 95 foci of prostate carcinoma (mean, 1.8 foci/case) from 52 completely embedded, mapped whole mount prostates. RESULTS: PIN contained a lower overall proportion of allelic imbalance than matched prostate carcinoma foci for the 6 polymorphic microsatellite markers (65% vs. 82%), but this difference was not significant. The rate of allelic imbalance in PIN was similar to that in prostate carcinoma at 5 of 6 loci studied; the exception, D18S34 (18q12.2-12.3), had a significantly lower rate of allelic imbalance in PIN than in prostate carcinoma (19% vs. 52%), suggesting that genetic alterations in this chromosomal region may be important in carcinogenesis. Of 22 cases with allelic imbalance in at least 1 focus of PIN and 1 focus of prostate carcinoma, 21 informative cases (95%) showed a similar pattern of allelic imbalance at > or = 1 markers in the matched PIN and prostate carcinoma foci. Significant genetic heterogeneity was observed in both PIN and prostate carcinoma. Allelic imbalance was observed in at least 1 focus in 11 of 25 cases with multiple foci of PIN (44%) and 20 of 25 cases with multiple foci of prostate carcinoma (80%). There was no significant correlation between allelic imbalance and pathologic stage or tumor grade. CONCLUSIONS: Our findings indicate that multiple foci of PIN arise independently within the same prostate. This observation suggests that a field effect underlies prostatic neoplasia. Multiple foci of prostate carcinoma also often arise independently, lending additional support for this hypothesis. The strong genetic similarities between PIN and prostate carcinoma strongly suggest that evolution and clonal expansion of PIN may account for the multifocal etiology of carcinomas.     

Mutation frequency declines during spermatogenesis in young mice but increases in old mice

Five percent of live-born human offspring will have a genetic disorder. Of these, 20% are because of germ-line de novo mutations. Several genetic diseases, such as neurofibromatosis and Duchenne muscular dystrophy, are associated with a high percentage of de novo germ-line mutations. Until recently, a direct analysis of spontaneous mutation frequencies in mammalian germ cells has been prevented by technical limitations. We have measured spontaneous mutation frequencies in a lacI transgene by using enriched populations of specific spermatogenic cell types. Similar to previously published results, we observed a lower mutation frequency for seminiferous tubule cell preparations, which contain all stages of spermatogenesis, relative to somatic tissues. We made the unexpected observation of a decline in mutation frequency during spermatogenesis, such that the mutation frequencies of type B spermatogonia and all subsequent stages of spermatogenesis are lower than the frequency for primitive type A spermatogonia. In addition, spermatogenic cells from old mice have significantly increased mutation frequencies compared with spermatogenic cells from young or middle-aged mice. Finally, the mutation frequency was observed to increase during spermiogenesis in postreplicative cell types when spermatogenic cells were obtained from old mice.     

Cytotoxicity of bile in human Hep G2 cells and in primary cultures of rat hepatocytes

There has been increasing interest in the development of a hepatocyte bioreactor for the treatment of acute hepatic failure; however, little is known about the effect of hepatocyte byproducts on the viability of the cells in the bioreactor environment. We investigated the effects of increasing concentrations of bile on the growth and viability of the human hepatoma cell line Hep G2 and on the cytochrome P-450 content and dependent mixed function oxidase (MFO) activities, reduced glutathione (GSH) content, and glutathione S-transferase (GST) activity of primary cultures of rat hepatocytes. Our purpose was to determine whether or not it would be necessary to pretreat the plasma from patients with acute liver failure to remove elevated bile concentrations which might be toxic to the hepatocytes in an artificial liver device. Bile was found to inhibit Hep G2 cell growth at concentrations as low as 0.1% and to decrease viability at concentrations above 0.5%. The cytochrome P-450 and GSH contents and the activities of the MFO system and of GST were decreased in the primary cultures of hepatocytes following 24 h treatment with concentrations of bile at and above 0.5%. The MFO activities associated with different cytochrome P-450 isoenzymes decreased to different extents in the presence of bile with the O-dealkylation of pentoxyresorufin being more labile than that of ethoxyresorufin. Our data indicate that elevated bile concentrations are cytotoxic to liver cells, and it may be necessary to pretreat patient plasma to decrease its bile content to protect the cells during the clinical operation of a hepatocyte bioreactor device.     

Proposed signal transduction role for conserved CheY residue Thr87, a member of the response regulator active-site quintet

CheY serves as a structural prototype for the response regulator proteins of two-component regulatory systems. Functional roles have previously been defined for four of the five highly conserved residues that form the response regulator active site, the exception being the hydroxy amino acid which corresponds to Thr87 in CheY. To investigate the contribution of Thr87 to signaling, we characterized, genetically and biochemically, several cheY mutants with amino acid substitutions at this position. The hydroxyl group appears to be necessary for effective chemotaxis, as a Thr-->Ser substitution was the only one of six tested which retained a Che+ swarm phenotype. Although nonchemotactic, cheY mutants with amino acid substitutions T87A and T87C could generate clockwise flagellar rotation either in the absence of CheZ, a protein that stimulates dephosphorylation of CheY, or when paired with a second site-activating mutation, Asp13-->Lys, demonstrating that a hydroxy amino acid at position 87 is not essential for activation of the flagellar switch. All purified mutant proteins examined phosphorylated efficiently from the CheA kinase in vitro but were impaired in autodephosphorylation. Thus, the mutant CheY proteins are phosphorylated to a greater degree than wild-type CheY yet support less clockwise flagellar rotation. The data imply that Thr87 is important for generating and/or stabilizing the phosphorylation-induced conformational change in CheY. Furthermore, the various position 87 substitutions differentially affected several properties of the mutant proteins. The chemotaxis and autodephosphorylation defects were tightly linked, suggesting common structural elements, whereas the effects on self-catalyzed and CheZ-mediated dephosphorylation of CheY were uncorrelated, suggesting different structural requirements for the two dephosphorylation reactions.     

Induction of immunologic refractoriness in adults by meningococcal C polysaccharide vaccination

Thirty-four adults were vaccinated with 1/50 of the usual dose of meningococcal polysaccharide vaccine (1 microg of A, C, Y, and W135 polysaccharides, given intramuscularly). This dose was selected as a probe to assess B cell memory. The probe elicited meningococcal C bactericidal antibody responses in all 18 adults who had been vaccinated 4 years earlier with an investigational meningococcal A and C oligosaccharide-protein conjugate vaccine and in the majority of the 11 subjects vaccinated for the first time. In contrast, the responses of the 5 adults given a full dose of licensed polysaccharide vaccine 4 years earlier were <1/10 of those of the other 2 groups. Thus, adults previously given a full dose of meningococcal polysaccharide vaccine show evidence of immunologic refractoriness to group C polysaccharide, whereas refractoriness is not observed after conjugate vaccination. These findings have implications for the use of meningococcal polysaccharide vaccine when the risk of disease is low.     

Effect of catecholamine depletion on myocardial infarct size in dogs: role of catecholamines in ischemic preconditioning

OBJECTIVES: Cardioprotective adaptation to brief periods of ischemia and reperfusion is termed ischemic preconditioning (PC). Limitation of infarct size by preconditioning is associated with marked slowing of ischemic metabolism. The cause of metabolic slowing has not been determined but may involve either pro- or anti-adrenergic mechanisms. Hypothetically, adrenergic stimulation could signal the adaptive response. Alternatively, metabolic slowing during the sustained ischemic challenge could occur through a reduction in beta-adrenergic stimulation. This study was designed to test the role of cardiac norepinephrine (NE) in PC. METHODS: The effect of PC on myocardial infarct size was studied in control dogs and dogs depleted of catecholamines by pretreatment with reserpine (RES; 0.25 mg/kg i.v.). PC was induced by four cycles of 5 min of ischemia and 5 min of reperfusion. Infarcts were produced by 60 min of ischemia and 3 h of reperfusion. Cardiac NE depletion was verified by radioimmunoassay of tissue samples and by absence of hemodynamic response to a tyramine bolus (1.4 mg/kg) administered at the end of each experiment. Infarct size, expressed as percent of area at risk, was controlled for variation in collateral blood flow using analysis of covariance (ANCOVA). RESULTS: Adjusted mean infarct size was 25.5 +/- 3.2% in untreated controls vs. 19.1 +/- 3.3% in RES-treated controls (P = NS). PC limited infarct size in untreated dogs (7.4 +/- 1.8 vs. 25.5 +/- 3.2%; PC vs. control; P < 0.01) but not in RES-treated dogs (15.7 +/- 3.0% vs. 19.1 +/- 3.3%; RES + PC vs. RES; P = NS). Infarct size was larger in dogs with RES + PC than with PC alone, even though there was a trend toward a slight beneficial effect with RES alone. CONCLUSION: The cardioprotective effect of ischemic preconditioning cannot be explained entirely as an anti-adrenergic effect. On the contrary, adrenergic receptor stimulation may be required for the full expression of ischemic preconditioning in canine myocardium.