Acta biologica et medica Germanica最新文献

Contents of relevant metabolites as well as incorporation of 14C from intravenously injected radioglucose in amino acids and proteins of selected brain areas from control and spontaneously hypertensive rats were investigated at appropriate times during the early life period. Adult SH-rats--26 to 28 weeks--differed from controls in having higher contents of glucose in cortex and hypothalamus, and in the latter region only of lactate and total alpha-amino-N. Accumulation of 14C was increased slightly over control activities in cortex and pontine-medullary area, but significantly in the hypothalamus. During the critical phase of rising blood pressure--8th to 15th week--, the incorporation of glucose-14C in hypothalamic amino acids of SH-rats increased markedly over puberty phase related activity levels of control animals. Flux of 14C to hypothalamic proteins exhibited similar stimulation and time pattern of protein synthesis. The results are interpreted as evidence for stimulation of the cerebral glucose metabolism in SH-rats, especially in the hypothalamus, during the phase of developmental hypertension over puberty period metabolism of control rats.

In 5- and 105-day-old rats the influence of intraperitoneally administered cations (Na+, K+, NH4+) and anions (Cl-, HCO3-) on the age-dependent distribution- and elimination processes of LiCl (0.3 mmol Li+/100 g b.wt., i.p.) were determined. After an acute load of sodium ions the renal elimination of lithium is increased and the half life (t 1/2 serum) is shortened. Compared with increased dosages of NaHCO3 equal doses of NaCl are more effective. Interactions in kidney between lithium and definite anions were observed on the bicarbonate ion only. The administrations of KCl or NH4Cl have no important consequences on lithium kinetics. Although the transport of lithium in kidney does not occur by the Na+K+-pump, renal and extrarenal interactions between sodium and lithium ions seem to exist. The expulsion of lithium out of the ICR by an extensive sodium load (decrease of VdLi+) may precede the observed inhibition on renal lithium reabsorption or both processes occur simultaneously.

The influence of acidic pH on the infectivity and neuraminidase activity of human, equine and avian type A influenza virus strains has been studied. Following exposure to pH 3 human and equine strains lost their infectivity completely, whereas all investigated strains of the subtypes Hav6N2 and Hav7Neq2 retained a certain amount of infectivity. In contrast to human and equine strains the avian strains retained also 38% of their original neuraminidase activity after acidic treatment. Partial retention of infectivity and the relative stability of the neuraminidase following exposure to acidic pH are supposed to be linked together in avian influenza virus strains implicating neuraminidases for their ability to prevent the aggregation of virions.

An indirect two-site binding enzyme immunoassay has been developed to quantify the pregnancy associated globulin (PAG) in rats. Anti-PAG from guinea pig is adsorbed to solid phase and binds serum-PAG, which then reacts with its remaining free determinants with anti-PAG from rabbit. Sheep anti-rabbit IgG, labeled with horse radish peroxidase (HRP), binds to the rabbit anti-PAG antibody and the enzymic activity of the solid phase is measured by incubation with the appropriate chromogenic substrate. The optical density is directly related to the quantity of PAG to be measured. Reproducible results are obtained in the range from 5 to 200 micrograms/l. The test detects 12 fmoles of PAG. Female rats show a 1000-fold higher serum level of PAG than male rats. Strain differences of the distribution of the PAG serum concentration were only found between male rats.

D-glucose reduces the outflow of manganese from pancreatic beta-cells in analogy to what has previously been reported for 45Ca. The decrease can be accounted for by an enhanced intracellular sequestration. The effect of D-glucose on manganese fluxes seems to be restricted to inhibition of the efflux; no stimulation of the influx being noted. The glucose-dependence of manganese uptake is hyperbolic with half maximal stimulation between 5 and 6 mM D-glucose.

Antibodies to normal Wistar rat islet cells are often found in newly diagnosed diabetic BB rats. It was tested if antibodies in BB rats bind to cells from a cloned insulin-producing, rat-insulinoma cell line, RIN 5F, using a protein A-radioligand assay for islet cell surface antibodies. A close correlation was found between the binding of antibodies to islet cells and to RIN 5F cells. Islet cell surface antibodies reactive with RIN 5 F cells were determined in two litters of BB rats, born by diabetic, islet cell surface antibody positive parents. A high incidence (85%) of diabetes was found among 13 offsprings, the mean age of onset being 88 days. At 44 days of age before diabetes was diagnosed, 95% of 20 offsprings were islet cell surface antibody positive. There was no difference in antibody-levels between diabetic and non-diabetic rats. It is concluded that BB rats have circulating antibodies reactive with surface determinants on the RIN-5F insulin-producing cell line. There was a high prevalence of islet cell surface antibodies among young, yet unaffected BB rats.

Differences in specific activities of elastase, myeloperoxidase, and lysozyme were found between polymorphonuclear leukocytes (PMNs) and macrophages of various species, between PMNs derived from different anatomic sites and between macrophages isolated in different ways. The percentage of extracellular release of lysosomal enzymes during immunological phagocytosis depends on the receptors in the phagocyte membrane which were stimulated by binding of a ligand. These differences may reflect various functional activities of separate populations of phagocytes.

Adrenaline causes aggregation of human blood platelets through stimulation of alpha-adrenoceptors resembling the alpha 2-type. Alpha-adrenoceptor blocking agents inhibit specifically the adrenaline-induced platelet reactions. The adrenaline-induced aggregation of human blood platelets was inhibited specifically by adrenergic neuron blocking agents such as guanoxan, guanclofine and guanethidine. Guanoxan (I50 = 0.6 mu mol/l) was about three orders of magnitude more effective than guanethidine, guanclofine occupied a median position. The compounds tested inhibited the ADP- and collagen-induced aggregation at relatively high concentrations. This is probably due to non-specific membrane effects. The known alpha-adrenolytic effect of guanoxan is believed to be mediated mainly by alpha 2-adrenoceptors.