The effects of guanine and cytosine variation on dinucleotide frequency and amino acid composition in the human genome

Summary One hundred twelve human DNA sequences were analyzed with respect to dinucleotide frequency and amino acid composition. The variation in guanine and cytosine (G+C) content revealed: (1) at 2–3 and 3-1 doublet positions CG discrimination is attenuated at high G+C, but TA disfavor is enhanced, and (2) several amino acids are subject to G+C change. These findings have been reported in part for collections of sequences from various species. The present study confirms that in a single organism-the human-the G+C effects do exist. Aspects of the argument that connects G+C with protein thermal stability are also discussed.     

Acidic fibroblast growth factor prevents death of hippocampal CA1 pyramidal cells following ischemia.

Ischemic insult induces neuronal death in the CA1 subfields of the hippocampus which are designated generally as the most vulnerable brain region. Recent studies have shown that acidic and basic fibroblast growth factors are potent trophic factors that support the survival of neurons in many brain regions including the hippocampus. Here we demonstrate that continuous infusion of acidic fibroblast growth factor into the lateral cerebral ventricles beginning 2 days before ischemia prevents the death of the CA1 pyramidal cells in the hippocampus of gerbils. Furthermore, delayed continuous administration of acidic fibroblast growth factor starting 5 min after ischemia is equally protective. The results suggest a possible physiological function for acidic fibroblast growth factor in the normal support of hippocampal CA1 pyramidal cells and neurons in some other brain regions in considering the broad spectrum of responsive neurons.     

Expression of intermediate filaments and other special markers by testicular germ cell tumors. With reference to embryogenesis.

Distribution of intermediate filament proteins (IFs) and several special markers was studied in 39 testicular germ cell tumors and 8 embryos and foetuses. The similarity and difference between development of germ cell tumor and embryogenesis were immunohistochemically investigated. Seminoma and embryonal carcinoma, as tumoral counterparts of undifferentiated germ cells, were characterized by little IF expression. This study revealed that the maturing and differentiating process in germ cell tumor is different from normal embryonal development and the tumor cells showed leaping maturing steps in tumorigenesis. Immunostaining for IFs helped to discover the further differentiation occurring in embryonal carcinoma and to demonstrate heterogeneous elements in non-seminoma germ cell tumors, which sometimes might not be apparent by light microscopical observation of H&E staining section. According to the findings, two patterns in mixed germ cell tumors are suggested; i.e., combined and diffuse types. The mechanism of tumorigenesis of the two types is supposed to be different. Clinically, the prognosis of most patients with testicular germ cell tumor is fairly good because of the improved chemotherapies that are dependent on histological diagnosis.     

Monoclonal antibodies that depress a specific subset of multiple components of the glutathione-induced response ofHydra

Summary Reduced glutathione evokes a feeding response, the tentacle-ball formation inHydra japonica. This response consists of at least 5 components (R1–R5). We raised 6 monoclonal antibodies (mAbs), each of which depressed a specific subset of these components, and we also examined the immunocytochemical localization of antigens with these mAbs at light microscopic level. The 2 mAbs that depressed R2 and R4 bound to the cnidocils of the desmoneme and the stenotele nematocytes; the 3 mAbs that depressed R5 bound to the apical surface adjacent to the cnidocils of the nematocytes; and the 2 mAbs that depressed R1 and R3 bound to the apical spot structures of unidentified cells in the ectoderm.Together with the specificity of the action of the mAbs on the behavioral response, the correspondence between the effects on the response and the structures visualized with these mAbs suggests that these structures include components of the receptor-effector system relevant to chemoreception.     

To what extent does a minimal atherosclerotic plaque alter the arterial wall shear stress distribution? A model study by an electrochemical method

An electrochemical surface shear stress measurement was applied to a model of very thin unilateral arterial stenosis (height of 1/8 of the model pipe diameter with very smooth surface). Three dimensional wall shear stress distribution was measured under steady flow field from a relatively low Reynolds number, Re = 270, to a high Reynolds number, Re = 1200. There was a characteristic high and low wall shear distribution pattern around the stenosis. There were also remarkable high shear stress areas on the opposite wall and both side walls of the stenosis. It was clearly shown that three dimensional structure of the flow field, hence, the wall shear stress distribution, is affected by a minimal change on the arterial wall.     

Insulin uptake by rat liver endothelium studied in fractionated liver cell suspensions

Summary Cellular distribution of insulin receptors was studied in fractionated rat liver cell suspensions using ¹²⁵1-insulin and a visual probe consisting of latex beads covalently linked to insulin (minibeads). Fractionation was done on metrizamide gradients which yielded two cellular fractions. The large cell fraction consisted mostly of hepatocytes and the small cell fraction consisted of 37% endothelial cells as well as Kupffer cells. The magnitude of insulin uptake by the endothelium-rich small cell fraction was at least double that of the uptake by the hepatocyte-rich fraction. The minibead technique demonstrated that in the small cell fraction only endothelial cells, and not Kupffer cells, were responsible for the insulin uptake. Our findings suggest that liver endothelium may be responsible for the uptake of circulating insulin and its transport to hepatocyte. This emphasizes the presence of a tissue-blood barrier in the liver.Abbreviations PRS phosphate-buffered saline - SEM scanning electron microscopy - TEM transmission electron microscopy