5′-Nucleotidase activity in liver homogenates of rats treated with CCl4, colchicine,cycloheximide, emetine,ethanol, ethionine and 5-fluorotryptophan

Summary 5-Nucleotidase activity, an enzyme marker of the plasma membranes, increases in female rat liver homogenates following ethionine administration, while homogenates from males show no changes. Treatment with CCl₄, colchicine, cycloheximide, emetine, ethanol and 5-fluorotryptophan does not significantly modify the 5-nucleotidase activity of liver homogenates of either female or male rats.     

β-Methyl carboline,a benzodiazepine inverse agonist,attenuates the effect of triazolam on the circadian rhythm of locomotor activity

Summary The benzodiazepine triazolam, the benzodiazepine inverse agonist, -methyl carboline (-CCM) or both, were administered to adult male hamsters under conditions of constant light. When given alone, triazolam induced phase advances in the circadian activity rhythm of about 90 min, while -CCM when given alone, had no effect on phase of the activity rhythm. However, when triazolam and -CCM were given at the same time, the magnitude of the phase advances induced by triazolam were attenuated to about 30 min. These data, in conjunction with previous results, provide pharmacological evidence for a GABAergic system involved in the regulation of a central circadian pacemaker.     

Presenilin-dependent regulated intramembrane proteolysis and γ-secretase activity

Inhibiting the production of amyloid-β by antagonising γ-secretase activity is currently being pursued as a therapeutic strategy for Alzheimer’s disease (AD). However, early pre-clinical studies have demonstrated that disruption of presenilin-dependent γ-secretase alters many presenilin-dependent processes, leading to early lethality in several AD model organisms. Subsequently, transgenic animal studies have highlighted several gross developmental side effects arising from presenilin deficiency. Partial knockdown or tissue-specific knockout of presenilins has identified the skin, vascular and immune systems as very sensitive to loss of presenilin functions. A more appreciative understanding of presenilin biology is therefore demanded if γ-secretase is to be pursued as a therapeutic target. Herein we review the current understanding of γ-secretase complexes; their regulation, abundance of interacting partners and diversity of substrates. We also discuss regulation of the γ-secretase complexes, with an emphasis on the functional role of presenilins in cell biology. Received 25 July 2008; received after revision 24 November 2008; accepted 10 December 2008     

Anti herpes simplex virus activity of lactoferrin/lactoferricin – an example of antiviral activity of antimicrobial protein/peptide

One of the most common viral infections in humans is caused by the herpes simplex virus (HSV). It was first effectively treated in the 1970s with the introduction of acyclovir, which is still the most commonly used treatment. Naturally occurring antimicrobial proteins and peptides have also been shown to possess antiviral activity against HSV. This review will focus on the anti-HSV activity of one such protein, lactoferrin, and a small peptide fragment from its N-terminal domain, lactoferricin. Both components have been shown to effectively block entry of HSV into the host cell. In addition to blocking HSV entry, the peptides appear to have immune stimulatory activity, although this is still somewhat controversial. Mode of action studies and knowledge about the anti-HSV activity of lactoferricin have also been successfully employed in the design of new, more specific HSV blockers. Received 25 May 2005; received after revision 24 August 2005; accepted 6 September 2005     

Influence of sex,developmental time and food onβ-N-acetylglucosaminidase activity in the rice weevilSitophilus oryzae L.

Summary The effects of some biological parameters on -N-acetylglucosaminidase activity have been investigated inS. oryzae. There is no significant influence of sex and developmental time on the enzyme activity level, which appears in contrast to be greatly influenced by food (wheat or sorghum). Sorghum contains competitive inhibitors which are almost completely removed after dialysis. Fasting relieves this inhibition very quickly, suggesting that inhibitors act directly at the gut level.     

Effects of duration of gonadectomy,sex and age on adrenal steroid 5α-reductase activity in the rat

Summary Within 6–8 weeks, gonadectomy in male and female rats leads to an increase in adrenal 5-steroid reductase activity. However, long-term post-orchiectomy enzyme activity decreases to the control level and this effect is not related to the age of animals.Supported in part by grant No.564/VI from Polish Academy of Sciences. Generous gift of hormones applied in these studies from The Upjohn Company, Kalamazoo, Michigan, USA is acknowledged.     

Dopamine-β-Hydroxylase activity in serum of developing rats

Summary After birth, the activity of dopamine--hydroxylase in rat serum increased up to 14 days maximal level and decreased gradully to reach a low level at 42 days which was about 14% of the activity of maximal activity at 14 days.     

Dopamine-β-hydroxylase activity in stroke-prone spontaneously hypertensive rats

Summary Dopamine--hydroxylase (DBH) activity was higher in the serum, the mesenteric artery and the cerebral cortex of 4-week-old stroke-prone spontaneously hypertensive rats (SHRSP), and lower in the nucleus tractus solitarii than it was in spontaneously hypertensive rats (SHR).The authors wish to thank Prof. Masao Sano (Nagoya University) for his aid in dissecting the nucleus tractus solitarii and the locus coeruleus.     

The structure of human interferon-β: implications for activity

Interferons (IFNs) are potent extracellular protein mediators of host defence and homoeostasis. This article reviews the structure of human IFN-β (HuIFN-β), in particular in relation to its activity. The recently determined crystal structure of HuIFN-β provides a framework for understanding of the mechanism of differentiation of type I IFNs by their common receptor. Insights are generated by comparison with the structures of other type I IFNs and from the interpretation of existing mutagenesis data. The details of the observed carbohydrate structure, together with biochemical data, implicate the glycosylation of HuIFN-β, which is uncommon among type I IFNs, as an important factor in the solubility, stability and, consequently, activity of the protein. Finally, these structural implications are discussed in the context of the clinical use of HuIFN-β. Received 12 June 1998; received after revision 16 July 1998; accepted 16 July 1998     

Does the moon influence the predatory activity of mites?

Periodicity in predatory activity was observed in overwintered females ofTyphlodromus pyri Scheuten (Acari: Phytoseiidae). Chronobiometrical analysis revealed that an approximately circabiseptan (about-14-day) rhythm is statistically significant, with a striking depression around the full moon.     

A new indolic antiauxin, α-(5,7-dichloroindole-3-)isobutyric acid: its chemical synthesis and biological activity

Summary A new potent antiauxin, -(5,7-dichloroindole-3-)isobutyric acid has been synthesized and shown to inhibit auxin-mediated elongation ofAvena coleoptiles and to stimulate root growth of rice seedlings. Its activity is stronger than -(p-chlorophenoxy)isobutyric acid and is comparable to that of 2,3,5-triiodobenzoic acid, which are typical antiauxins.     

Changes in dopamineβ-hydroxylase activity of monkey plasma with age

Summary Plasma dopamine -hydroxylase activity of Japanese monkeys (Macaca fuscata fuscata) increased with age, and the developmental changes were similar to those of human beings. However, the adult level plasma DBH activity of various monkey species was much lower than that of human beings.We thank Dr.K. Nozawa, Dr.O. Takenaka and Mr.T. Shotake (Primate Research Institute, Kyoto University) for their help in collecting monkey blood samples.     

Effects of N2, O2′-dibutyril cyclic GMP on the nucleoside phosphotransferase activity of the retina of the chick embryos

Summary In the retina of the chick embryo, 2 different forms of nucleoside phosphotransferase take part in the phosphorylation of thymidine. One is an unstable form with higher molecular weight. The other with lower m. wt is a stable form. This paper shows that N², O²-dibutyril cyclic GMP causes a marked decrement of the activity of the unstable nucleoside phosphotransferase.     

Elevation of plasma dopamine-β-hydroxylase activity during insulin-induced hypoglycemia in man

Résumé Nous avons étudié l'activité de la dopamine--hydroxylase du plasma humain. Elle a été remarquablement accure par l'administration de grandes quantités d'insuline. Les corrélations entre cette activité et celle des systèmes nerveux sympathiques sont également discutées.     

Estrogenic activity and steric hindrance to coplanarity of alkyl substituted 4,4′-dimethoxystilbenes

Zusammenfassung Für eine Reihe Methyl- bzw. Äthylsubstituierter 4,4-Dimethoxystilbene ist die relative östrogene Wirksamkeit ermittelt worden. Dabei ergab sich eine Parallele zwischen der Aktivität und dem Grad der sterischen Hinderung, welche die Koplanarität der beiden Phenylkerne aufhebt. Maximale Wirksamkeit konnte auch mit Methyl-, nicht nur mit Äthylgruppen an der Doppelbindung erreicht werden.

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The contents of this paper have been reported in more detail in the thesis ofW. H. Laarhoven, Leiden (1959).     

β-alanine and α-L-alanine inhibit the exploratory activity of spontaneously hypertensive rats

Summary 1% -alanine and -L-alanine, when given for 7 days as the only drinking fluid, inhibited the exploratory activity of adult male spontaneously-hypertensive rats (SHR)_but not that of the normotensive Wistar-Kyoto rats (WKR). -Alanine decreased the taurine level in the liver of both strains and in the platelets of SHR. -Alanine decreased the taurine level in the liver of WKR and in the platelets of SHR.This study was supported by the Sigrid Jusélius Foundation.     

Increase in cystathionine β-synthase activity in the liver of rats treated withl-ethionine

Résumé Une seule injection d'éthionine (400 mg/kg) provoque une augmentation significative de l'activité de la cystathionine -synthase du foie de rat. La méthionine empêche l'effect de l'éthionine, tandis que l'actinomycine D, le cycloheximide, la méthionine sulfoximine, la méthionine sulfona et l'ATP ne le modifient pas. In vitro, l'éthionine n'a aucune influence sur l'activité de la cystathionine synthase hépatique.

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This work was supported by the Serbian Medical Research Foundation.     

Selective activity of morphine on the ‘EEG arousal reaction’ to painful stimuli

Résumé L'action de la morphine sur l'activité électrique cérébrale a été étudiée sur le lapin ni anesthésié ni curarisé. La réaction d'arrêt, qui se traduit par une désynchronisation du tracé EEG, consécutive à un stimulus douloureux (stimulation du nerf sciatique, pincement de l'oreille) est abolie par des doses de morphine qui n'influencent pas les modifications analogues du tracé EEG provoquées par les stimulations sensitives ou sensorielles (stimulation olfactive, acoustique ou tactile).Une telle spécificité, qui n'apparaît pas dans le cas de la scopolamine et des barbituriques (Pentobarbital), peut être mise en rapport avec l'action analgésique caractéristique de la morphine.