Effects of nucleoside triphosphates on choleragen-activated brain adenylate cyclase.

To investigate the effects of nucleoside triphosphates on the activation of adenylate cyclase by choleragen and on the stability and catalytic function of the choleragen-activated enzyme, we treated samples of particulate preparation from bovine brain successively in three separate incubations with extensive washing between each step. In incubation I, choleragen and NAD were pesent to activte the adenylate cyclase. In incubation II, conditions were varied to assess enzyme stability.

Products of reaction catalyzed by purified rat liver guanylate cyclase determined by 31p NMR spectroscopy.

Products of the reactions catalyzed by highly purified preparations of soluble guanylate cyclase [GTP pyrophosphate-lyase (cyclizing), EC 4.6.1.

Elevation of lysosomal enzymes in primary Lewis lung tumor correlated with the initiation of metastasis.

Lysosomal enzymes were elevated about two-fold in primary s.c. Lewis lung carcinoma as compared with metastatic nodules in the lung.

Circular dichroism spectra show that repeating dinucleotide DNAs may form helices in which every other base is looped out.

We have found that the CD spectrum of poly [d(C-T)] undergoes a marked change upon protonation, taking on the unmistakable features of the spectrum of poly[d(C) x d(C+)]. The acid poly[d9C-T)] structure appears to be one in which each of the T residues is individually looped out of a helix formed by stacked C x C+ base pairs. We also present data for poly[d(C-A)] and review data for the other four possible repeating DNA dinucleotide sequences.

ADP-ribosyltransferase activity of mono- and multi-(ADP-ribosylated) choleragen.

Choleragen (cholera toxin) catalyzed the NAD-dependent auto-ADP-ribosyltation of its A1 peptide. The number of ADP-ribose moieties incorporated into ech A1 peptide was dependent on incubation conditions and time as well as toxin concentration. There was no evidence for the formation of poly(ADP-ribosylated) toxin.

Naloxone inhibits arginine vasotocin- (AVT) induced prolactin release in urethane-anesthetized male rats in vivo.

Arginine vasotocin (AVT) (1 microgram) elicited a two-fold increase in serum prolactin (Prl) levels 10 min following its i.v. injection into urethane-anesthetized adult male rats.

Effects of GTP on choleragen-catalyzed ADP ribosylation of membrane and soluble proteins.

Choleragen-dependent ADP ribosylation of soluble proteins from bovine thymus, using [32P]NAD as substrate, was increased 3- to 4-fold by GTP. The effect was specific for nucleoside triphosphate, with GTP approximately equal to ITP greater than CTP greater than ATP greater than UTP. Half-maximal enhancement was observed with 0.

The validity of the Modified Word Learning Test.

Inspected reports on 59 psychiatric patients who had completed the Modified Word Learning Test (MWLT), Memory for Designs Test, and the Wechsler Adult Intelligence Scale in order to assess the validity of the MWLT. It was found that MWLT scores were correlated with age, Verbal Scale and Full Scale IQs and Verbal-Performance Discrepancies. In additon, there was 61% agreement in classification with the Memory for Designs Test.

Influence of pinealectomy on corticotropin (ACTH).

Sensory deprivation produced by removing the eyes and olfactory bulbs in male rats allowed pinealectomy to markedly augment the post-adrenalectomy elevation of ACTH levels. Pineal removal or sensory deprivation separately did not have this effect. Thus, intact sensory input and an intact pineal gland are independently capable of restricting the post-adrenalectomy rise in ACTH levels.

Prostaglandins increase GTP hydrolysis by membranes from human mononuclear cells.

Both adenylate cyclase and GTPase activities in human mononuclear cell membranes were increased by prostaglandins. Adenylate cyclase activity, however, was enhanced by much lower concentrations of PGE1 (prostaglandin E1) than were required to increase GTPase. PGE2, PGA1, PGB1, and PGF1 alpha also stimulated GTPase activity.

Synthesis of proteins and RNA of the 60S ribosomal subunit in HeLa cells recovering from valine deprivation.

The synthesis of ribosomes in HeLa cells was studied during recovery from a 20-hour deprivation for valine. The rates of incorporation of labeled precursors into ribosomal pre-RNA, processed rRNA, total cellular proteins, and proteins of the 60S ribosomal subunit returned to normal or nearly normal levels immediately after restoration of valine to the medium. Specific proteins of the 60S ribosomal subunit, whose apparent net synthesis is reduced more than that of the other proteins of the 60S ribosomal subunit during valine deprivation, were no longer undersynthesized after valine was restored.

Quantification of low density lipoprotein binding and cholesterol accumulation by single human fibroblasts using fluorescence microscopy.

Using fluorescence microscopy, we have quantified low density lipoprotein (LDL) binding by indirect immunofluorescence and cellular cholesterol with the fluorescent sterol-binding polyene, filipin, in individual cultured human fibroblasts from normal subjects and from patients with heterozygous and homozygous familial hypercholesterolemia. LDL binding by fibroblasts from heterozygous patients was about 40% of that of the normal cells, and cholesterol accumulation upon incubation with LDL was decreased to a similar degree. Most fibroblasts from homozygous patients bound no detectable LDL and only rare cells demonstrated any accumulation of cholesterol after incubation with LDL.

Acute effects of arginine vasotocin on plasma and pituitary levels of prolactin in the male rat: influence of urethane anesthesia.

The acute effects of arginine vasotocin (AVT), a putative pineal peptide, on plasma levels of prolactin were investigated in the unanesthetized, estrogen-progesterone-treated male rat. A 10-microgram s.c.

Effect of cell density on binding and uptake of low density lipoprotein by human fibroblasts.

The effect of cell density on low density lipoprotein (LDL) binding by cultured human skin fibroblasts was investigated. Bound LDL was visualized by indirect immunofluorescence. Cellular lipid and cholesterol were monitored by fluorescence in cells stained with phosphine 3R and filipin, respectively.

Sequential adsorption-electrophoresis: combined procedure for purification of calcium-dependent cyclic nucleotide phosphodiesterase.

A procedure for combined sequential affinity adsorption-electrophoresis has been devised. Its use for the rapid purification of a calcium-dependent cyclic nucleotide phosphodiesterase from bovine brain in high yield is described. In this procedure, proteins bound to a solid phase of calcium-dependent regulatory protein (CDR) linked to Sepharose 4B were electrophoretically eluted, concentrated, and separated, thus avoiding the large losses in activity incurred during attempts to purify further the phosphodiesterase eluted by conventional means.

Elevated blood pressure after pinealectomy in the rat.

Previous observations have suggested a role for the pineal gland in regulation of blood pressure. To investigate this possibility, pinealectomy was performed in prepubertal (43-day-old) and postpubertal (55-day-old) male rats. Systolic blood pressure (BP) was measured by the tail cuff method in conscious pinealectomized (Px) and sham pinealectomized (ShPx) rats at various times.

Arrest of cultured cells in the G1 phase of the cell cycle by indomethacin.

Indomethacin reversibly inhibited growth of rat hepatoma cells (HTC) and human diploid fibroblasts in the G1 phase of the cell cycle. Cytophotometric measurements showed that greater than 90% of cells incubated for 48 hr with indomethacin had a DNA content that corresponded to the G1 state. Synchronous growth of both the HTC and fibroblast cultures occurred after removal of drug as indicated by the sequence of changes in [3H]thymidine incorporation into DNA, cellular DNA content, mitotic index and cell number.

Effects of spermine on activity and stability of calcium-dependent guanosine 3',5'-monophosphate phosphodiesterase.

Spermine in micromolar concentrations decreased the basal activity of a guanosine 3',5'-monophosphate (cGMP) phosphodiesterase from bovine brain but had no effect in the presence of Ca2+ plus the calcium-dependent regulatory protein (CDR) which increased the activity of the enzyme 4- to 6-fold. Similar effects of spermine were observed on the enzyme at several stages of purification. Spermidine and putrescine were also inhibitory but higher concentrations were required.

Interaction of daily injections and subcutaneous reservoirs of melatonin on the reproductive physiology of female Syrian hamsters.

This study investigated the ability of continuously available melatonin (from sc melatonin-beeswax pellets that were implanted bi-weekly) in overcoming the antigonadotrophic action of single daily melatonin (25 microgram) injections given late in the light period to female Syrian hamsters kept in light:dark cycles of 14:10. The melatonin-beeswax pellets contained either 1, 50, 500 microgram, 1 or 10 mg melatonin and 25 mg beeswax. Daily melatonin injections into hamsters implanted with beeswax only caused vaginal acyclicity in 60% of the animals within 6 weeks.

Isolation and characterization of a cycloheximide-resistant mutant of Acanthamoeba castellanii Neff.

A cycloheximide-resistant mutant was isolated from the amoeba Acanthamoeba castellanii Neff. Drug resistance was found to be due to a ribosomal modification.