The effects of injection of amphetamine on female insemination in the black blow fly, Phormia regina (Diptera: Calliphoridae)

Abstract. An earlier study on the blowfly Phormia regina (Meigen) demonstrated that the injection of amphetamine (12 μg) depletes biogenic amine levels in the CNS. In the present study, P. regina females were injected with amphetamine (12 μg), each female was placed with three males and insemination success was determined. Amphetamine inhibited female insemination by 43.3% at 2–90 min post-injection and by 70% at 10–60 min post-injection. At 180–270 min post-injection, there was no significant inhibition of female insemination. This study indicates a possible role in insects for the biogenic amines in female insemination.     

Record performances at the Boston Marathon: Biometeorological factors

Air temperature and relative humidity have long been suspected of affecting the performance of marathon runners. Though these factors are important in their extremes, we show that other factors are even more indicative of race performances. Performances of the top 3 finishers in the last 30 Boston Marathons were correlated with hourly meteorological data for each race day. These 90 individual performances were classified as: record breaking performances (31), average performances (35), and unusually slow performances (24). The factors that help predict record breaking and unusually slow performances are: (i) wet bulb temperature, (ii) percent sky cover, and (iii) presence or absence of a light precipitation. Record breaking performances are characterized by a wet bulb temperature of <7.8°C, and 100% sky cover. A light drizzle is also conducive to better performances. On the other hand, unusually low performances are accompanied by a wet bulb temperature of >7.8°C, and a sky cover of 50% or less. No light, precipitation was recorded on any of the unusually slow race days. A graphic analysis clearly shows these relationships to exist. In addition, a multiple regression analysis confirms the importance of these variables. The authors advise that these are reliable predictors; however, when considering marathon races held in various geographical regions and differing climatic regimes, the exact numerical thresholds used here may not apply.     

The structure of the metal-nucleotide complex substrate for yeast hexokinase

A comparison has been made of the kinetic parameters obtained with yeast hexokinase using Mg²⁺ or Ni²⁺ as metal ion activator and ATP or tubercidin-5′-triphosphate as nucleotide substrate. It is concluded that the relative specificity of the enzyme for MgATP^2? does not involve a contribution arising from an interaction of the metal ion with the purine ring of the nucleotide.     

Changes in cerebral blood flow during a migraine attack.

Regional cerebral blood flow studies during a typical prodromal phase of a migraine attack in a young woman showed a global decrease of cerebral blood flow in the carotid artery territory. These studies were repeated during the subsequent headache phase of the same attack and hemispheric blood flow increased considerably. Ergotamine tartrate was then administered intramuscularly which brought definite relief of symptoms but no change in cerebral blood flow. Carotid angiography performed immediately afterwards showed retrograde filling of the proximal portion of the basilar artery, which suggested that the brain stem was the site of hyper-perfusion. These findings illustrate certain features underlying both the pathophysiology of migraine itself and its response to ergotamine preparations.