Fibrin-induced release of platelet serotonin

Human platelets were reacted with polymerized fibrin formed from human fibrinogen. The platelets adhered to the fibrin particles and this adhesion was followed by the release of serotonin from prelabeled platelets. The adhesion of platelets to fibrin was not inhibited by adenosine or prostaglandin E1. However, the subsequent Ca2+-dependent release of platelet serotonin was completely inhibited by these compounds. After the initial platelet-fibrin interaction, ADP and serotonin released from activated platelets may lead to additional platelet aggregation and release. Therefore, in addition to clot stabilization, fibrin serves as an initiator of the platelet release reaction. This in turn initiates the self-amplifying process of platelet aggregation.     

Diurnal periodicity of mitotic activity, DNA synthesis and duration of mitosis in mouse bone marrow cells

A clear diurnal rythm of the mitotic activity and DNA synthesis was observed in the cells of myeloid and erythroid series of mouse bone marrow, maximum number of mitoses and DNA-synthesising cells coincided in time and occurred during day and night hours minimum--during morning and evening hours. A rise in the mititic activity was due to the increase in the number of dividing cells but not to the increase in duration of mitosis.     

Multimode field theory explanation of kinks in the characteristics of DH lasers

A detailed field theory for DH lasers is developed. Two transversal modes are taken into account, and the theory is able to account for kinks in the light-current characteristics even for ideal lasers.     

Composition of uropygial gland secretions of birds of prey

The chemical composition of the uropygial gland secretion of five species of birds of prey was investigated by gas liquid chromatography-mass spectroscopy technique, and the results are discussed from the chemotaxonomical point of view. The secretion is a complex mixture of monoester waxes, the fatty acids of which are mainly dimethyl-branched, with the first substituent in 2 position and the other near the methyl end of the molecule. Mono-, trimethyl-, and unbranched fatty acids also are observed. The wax alcohols are mainly mono- and dimethyl-substituted. Unbranched alcohols and traces of trimethyl-substituted alcohols also were detected. Chemotaxonomically, the birds of prey differ from all orders hitherto investigated. The degree of substitution increases from theFalconidae to theAccipitridae.     

Altered calcium channel currents in Purkinje cells of the neurological mutant mouse leaner

Mutations of the alpha1A calcium channel subunit have been shown to cause such human neurological diseases as familial hemiplegic migraine, episodic ataxia-2, and spinocerebellar ataxia 6 and also to cause the murine neurological phenotypes of tottering and leaner. The leaner phenotype is recessive and characterized by ataxia with cortical spike and wave discharges (similar to absence epilepsy in humans) and a gradual degeneration of cerebellar Purkinje and granule cells. The mutation responsible is a single-base substitution that produces truncation of the normal open reading frame beyond repeat IV and expression of a novel C-terminal sequence. Here, we have used whole-cell recordings to determine whether the leaner mutation alters calcium channel currents in cerebellar Purkinje cells, both because these cells are profoundly affected in leaner mice and because they normally express high levels of alpha1A. In Purkinje cells from normal mice, 82% of the whole-cell current was blocked by 100 nM omega-agatoxin-IVA. In Purkinje cells from homozygous leaner mice, this omega-agatoxin-IVA-sensitive current was 65% smaller than in control cells. Although attenuated, the omega-agatoxin-IVA-sensitive current in homozygous leaner cells had properties indistinguishable from that of normal Purkinje neurons. Additionally, the omega-agatoxin-IVA-insensitive current was unaffected in homozygous leaner mice. Thus, the leaner mutation selectively reduces P-type currents in Purkinje cells, and the alpha1A subunit and P-type current appear to be essential for normal cerebellar function.     

Tips in diagnosing fetal skeletal anomalies

Target set size refers to the number of preexisting connections a studied word has to closely related concepts in long-term memory. The purpose of this investigation was to determine whether target set size influences feeling-of-knowing (FOK) ratings. The results showed that ratings were higher for targets connected to smaller sets, as compared with those connected to larger sets. Comparable effects were obtained with the use of different encoding strategies, including concreteness classifications and vowel naming, and with both meaningfully and phonologically related test cues. These findings indicate that FOKs are sensitive to competition between concepts linked to the target and that this sensitivity is independent of encoding strategy and type of test cue. Response time measures indicated that FOKs are sensitive to competition that arises when concepts are activated in parallel, whereas recall is more sensitive to competition that arises during sampling associated with search. Implications for various cue-based and target-based explanations of FOK effects are discussed.