Effect of disulfiram on turnover of 5-hydroxytryptamine in rat brain.

Effect of disulfiram on 5-hydroxytryptamine (5-HT) turnover was studied. Treatment with disulfiram caused increases in 5-HT and 5-hydroxyindoleacetic acid (5-HIAA) in rat brain. Under the same condition, activity of brain mitochondrial aldehyde dehydrogenase was reduced, however, supernatant aldehyde dehydrogenase and monoamine oxidase activities remained unchanged. Disulfiram had no effect on synthesis rate of 5-HT, but decreased metabolism of 5-HT. Moreover, disulfiram impaired transport of 5-HIAA from brain tissue.     

Effects of morphine on visual evoked responses recorded in five brain sites.

The effects of morphine on averaged evoked responses to visual stimulation were examined in specific brain structures relevant to pain, analgesia, tolerance and motor disturbances. Permanent electrodes (60 μ in diameter) were implanted stereotaxically in the central gray, mesencephalic reticular formation, caudate nucleus, parafasicular-centromedian complex and the lateral geniculate body as a control site. Visual evoked responses were obtained in unanesthetized, unrestrained rats prior to and following the administration of morphine in successive doses of 1, 5, 10 and 30 mg/kg and 1 mg/kg of naloxone (a morphine antagonist). The parafasicular-centromedian complex and the reticular formation exibited a progressive increase in response amplitude to increased dose of morphine. These effects were reversed by naloxone. In this study the parafasicular-centromedian complex was found to be the most sensitive structure to morphine, displaying the largest changes in response amplitude as a result of morphine administration.     

Stimulation of gastrin secretion from the perfused rat stomach by somatostatin antiserum

The effect of a high capacity somatostatin antiserum on antral gastrin secretion was examined in an isolated vascularly perfused rat stomach preparation. Infusion of somatostatin antiserum diluted 1:1 and 1:9 with Krebs buffer solution produced significant increases in gastrin secretion throughout the period of infusion. Neither infusion of somatostatin antiserum diluted 1:99 nor infusion of control rabbit serum had any effect on gastrin secretion. The data indicate that antral somatostatin excercises a continous restraint on gastrin secretion in the basal state.     

Critical importance of microsome concentration in mutagenesis assay with V79 Chinese hamster cells.

For optimum mutagensis in V79 Chinese hamster cells, the amount of liver postmitochondrial fraction in the assay was found to be of critical importance, depending on the chemicals being tested. Benzo[a]pyrene (BP) required lower (1-5%) concentrations of the liver 15 000 X g supernatant (S15) from methylcholanthrene pretreated rats for a maximum induction of cytotoxicity and mutagenicity, as determined by 8-azaguanine- and ouabain-resistance. A sharp peak of mutagenicity and cytotoxicity was induced by 7,8-dihydroxy-7,8-dihydrobenzo[a]pyrene (7,8-diol BP) at a concentration of 1% of the S15 fraction. Little or no response was induced by these compounds with the S15 concentrations of more than 10%. Similarly, aflatoxin B1 induced a sharp peak of mutagenicity and cytotoxicity at a concentration of 2% of the liver S15 fraction from Aroclor-pretreated rats. Under the same condition, non-carcinogenic aflatoxin G2 did not induce cytotoxicity and mutagenicity. Analysis of BP metabolites by high-pressure liquid chromatography indicates that with the 30% S15 fraction, more than 80% of BP was metabolized during the first 15 min, while with the 2% S15 fraction, 7,8-diol BP increased continuously throughout the 120-min incubation period, suggesting a strong metabolic competition to rapidly remove BP and 7,8-diol BP with a high concentration of the S15. In contrast with these compounds, N-nitrosodimethylamine induced mutagenicity and cytotoxicity which increased linearly in proportion to the increasing amount of the S15 fraction from phenobarbitone- and Aroclor-pretreated rats. Various nitrosamines with different lipophilicity were examined at a high (30%) and low (2%) concentration of the S15 fraction from Aroclor-pretreated rats, in which ratios of mutation frequencies at 30% and 2% correlated inversely with lipophilicity of the compound. This result suggests that the lipid solubility of test compounds may be one factor which determines the concentration of post-mitochondrial supernatant for optimum mutagenesis.     

Mitochondrial mutagenesis in Saccharomyces cerevisiae. III. Nitrous acid.

Nitrous acid (NA) induced mutations efficiently in mitDNA, conferring resistance to erythromycin and weakly induces mit- mutations. In some strains of yeast it also enhanced rho- mutations. The frequencies of nuclear and mitochondrial mutations induced with NA are compared.     

Effects of inorganic amendments (N,P and K) to soil on the rhizosphere microflora of antirrhinum plants infected withVerticillium dahliae Kleb

Summary A study of the inorganic amendments (N, P and K) to soil, and their effect on the rhizosphere microflora, as well as their relation to the control of wilt of antirrhinum plants caused byVerticillium dahliae Kleb. was done. Ammonium sulphate was the only chemical found to be significantly inhibitory toV. dahliae in vitro. Soil amendments (NPK) affected the rhizosphere microorganisms of the antirrhinum plants. Higher concentration of the chemicals were phytotoxic. It was further observed that ammonium sulphate, and the combined chemicals (NPK 25%) in soil delayed the senescence in healthy plants, suggests that chemical fertilisers affected the host plants directly. Addition of ammonium sulphate (0.25%), calcium nitrate (0.25%, 0.5%) combined NPK (0.25%) to soil caused considerable reduction in disease severity. It is assumed that this reduction may be caused by the (1) fungitoxic nature of the chemicali.e. ammonium sulphate, (2) antagonistic environment for the pathogen in the rhizosphere was boostedi.e. where calcium nitrate was added as soil amendments and (3) reduction in disease severity in soil-amended with combined NPK, may be due to the fact that antagonistic actinomycete population was boosted in the rhizosphere.     

Comparison of the nucleotide sequence of cloned DNA coding for an apolipoprotein (apoVLDL-II) from avian blood and the amino acid sequence of an egg-yolk protein (apovitellenin I): equivalence of the two sequences

We have compared the amino acid sequences of two low-molecular-weight avian apoproteins: apoVLDL-II from very low-density lipoproteins of hen plasma and apovitellenin I from hen egg yolk. The sequence of White Leghorn apoVLDL-II was derived from the nucleotide sequence of cloned apoVLDL-II DNA (Chan et al., 1980). The sequenator was used to determine the amino acid sequence of apovitellinin I from two breeds of hen (White Leghorn and Australorp). The sequences from the two breeds were not only identical, but they also completely matched the predicted sequence derived from the apoVLDL-II DNA sequence. The identity reported here establishes that this protein is transported intact from the blood to the egg yolk.     

Effects of weaning age on mortality of colony-born Macaca nemestrina

In an effort to determine empirically the proper age for separation of pigtailed macaque (Macaca nemestrina ) infants from their dams in a large domestic breeding colony, we conducted a retrospective survey of 1,592 infants. Survivorship was highest for infants not separated from their dams at all and for those separated within the first four months of life. Survivorship was poor for animals separated during or after the fifth month. Thus, not weaning or weaning early are the most acceptable management strategies in terms of mortality risk. This result is paradoxical with regard to nutritional considerations, but appears to be related to a sensitive period in social development. The relative advantages and disadvantages of various weaning ages are discussed.     

Altered adenosine triphosphatase activities of natural actomyosin from rat hearts perfused with isoprenaline and ouabain

Perfused rat hearts were treated with isoprenaline (10^?6M) or ouabain (5.5 × 10^?6M). The phosphate contents of troponin-I and myosin P light chains were established by radiolabelling with ³²P; in the case of the light chains, direct chemical analysis of total and of specifically alkali-labile phosphate was also performed. Addition of isoprenaline caused phosphorylation of both troponin-I and myosin P light chains, reaching a maximum increment, after several minutes, of 1 mol/mol and 0.30 mol/mol, respectively. The Mg²⁺-ATPase activities, at saturating Ca²⁺ concentrations, of natural actomyosin isolated from treated hearts were significantly depressed, and an inverse correlation was established between the phosphate content of troponin-I and the V_max[Ca²⁺] of this ATPase activity. The Ca²⁺ sensitivity of the $\text{Ca}{}^{\mathrm{2+}}\text{Mg}{}^{\mathrm{2+}}\text{-ATPase}$ was also decreased. These changes were all reversed by an incubation permitting dephosphorylation of proteins by endogenous phosphatases.Treatment of hearts with ouabain caused no increment in troponin-I phosphorylation, but increased the P light chain phosphate content to a maximum of 0.30 mol/mol after some minutes. A positive correlation was evident between phosphate content of the light chains (in all experiments) and the maximum myosin Ca²⁺-ATPase activities. In addition, the V_max[ATP] of the $\text{Ca}{}^{\mathrm{2+}}\text{Mg}{}^{\mathrm{2+}}\text{-ATPase}$ of natural actomyosin was increased when light chain phosphorylation had occurred in the absence of troponin-I phosphorylation. P-light chain phosphorylation did not affect the Ca²⁺ sensitivity of $\text{Ca}{}^{\mathrm{2+}}\text{Mg}{}^{\mathrm{2+}}\text{-ATPase}$ activity.We suggest that the effects of phosphorylation of troponin-I are to diminish thin filament sensitivity to Ca²⁺, and to decrease the efficiency of the transduction process along neighbouring actin monomers, such that the number of actin-myosin crossbridge interactions is decreased even in the presence of Ca²⁺ excess. Phosphorylation of P light chains of myosin has an activating effect on myosin Ca²⁺-ATPase activity, as well as on the rate of cross-bridge formation.     

Stimulation by calmodulin of Ca2+ uptake and (Ca2+-Mg2+) ATPase activity in membrane fractions from ox neurohypophyses

Calmodulin stimulated ⁴⁵Ca²⁺ uptake into a plasma membrane enriched fraction from ox neurohypophysial nerve endings and into a microsome fraction. The ⁴⁵Ca²⁺ uptake and the (Ca²⁺-Mg²⁺) ATPase activity in the plasma membrane fraction exhibited similar pCa and calmodulin sensitivities, suggesting that the enzyme activity is the biochemical expression of a high affinity Ca²⁺ pump. Calmodulin thus seems to play a role in regulation of the intracellular free Ca²⁺ concentration in the neurohypophysis.