Control of the Ca2+-triggered bioluminescence of Veretillum cynomorium lumisomes

Calcium ions can trigger an emission of light from Veretillum cynomorium lumisomes (bioluminescent vesicles) under conditions where they are not lysed. This process does not require a metabolically-linked source of energy, but is dependent upon the nature of the ions present inside and outside the vesicles. The Ca2+-triggered bioluminescence is stimulated by an asymmetrical distribution of cations or anions. Either high internal sodium or high external chloride is required for the maximal effect. When sodium is present outside the structure and potassium inside, the slow inward diffusion of calcium is decreased. Unbalanced diffusion of internal cations also stimulates the bioluminescence, suggesting control of the calcium influx by an electrochemical gradient. It is assumed that rapid outward diffusion of sodium or inward diffusion of chloride generates an electrical potential difference (inside negative) which drives the Ca2+-influx. With purified lumisomes it has been shown that Ca2+-triggered bioluminescence and calcium uptake (presumably net uptake) were correlated. In two instances uptake of the lipophilic cation dibenzyldimethylammonium has given direct evidence for the existence of a potential difference. With NaCl-loaded vesicles, it has not been possible to demonstrate an uptake of lipophilic cations but experiments with 22Na and 42D indicated a higher rate of sodium efflux, in accord with the proposed hypothesis.

GLC determination of caffeine in plasma using alkali flame detection

A rapid, specific, and sensitive GLC assay for caffeine in plasma was developed utilizing alkali flame-ionization detection. The procedure involves the addition of mepivacaine as an internal standard, alkalinization of the sample, and extraction with chloroform. Peak height ratio measurements produced linear standard curves in the 0.25-10.0-microgram/ml range. Absolute sensitivity from a 1.0-ml plasma sample was 0.1 microgram/ml. The relative standard deviation of a 2.0-microgram/ml pooled plasma standard run repeatedly over several months was 5.2%. The method is applicable to time-concentration studies in human and animal plasma following typical oral doses of caffeine.

Case reports and studies of paraneoplastic hypotension: abnormal low pressure baroreceptor responses

Intrathoracic stretch receptors regulate adjustments of the vasculature to gravitational changes and influence urinary water and solute excretion. Few reports of pathologic states involving interruption of these regulatory mechanisms have appeared. Two patients with orthostatic hypotenstion related to advanced intrathoracic carcinoma were studied, utilizing tilt-table examinations and immersion of the entire body in water to test the function of their intrathoracic baroreceptor reflex arcs. Both patients showed abnormalities of antidiuretic hormone level and sodium excretion as compared with normal controls. This suggests that total immersion is a safe and convenient test of the low-pressure baroreceptor system in patients with suspected dysfunction. Three patients are also reported whose charts were reviewed posthumously. Although they were not tested in the laboratory, their clinical data suggest that they too had been suffering from an interference with the transmission of impulses from the intrathoracic receptors.

Characterization and properties of Pholas luciferase as a metalloglycoprotein

The luciferase of the bioluminescent boring mollusc, Pholas dactylus, has been purified by a new method which includes centrifugation in cesium chloride gradients. Homogeneous preparations have been obtained and molecular weight determinations and subunit analysis support the idea that this preparation is an oxyluciferin-luciferase complex. The preparation catalyzes oxidation of ascorbic acid in presence of H2O2, and this peroxidase activitity has been used for characterization (thermal and pH stabilities, activity as a function of pH, isoelectric point, turnover number). The existence of two atoms of copper has been established and their involvement in the peroxidase activity indicated. Chemical analyses have shown that Pholad luciferase is a glycoprotein and the existence of glucosamine, fucose, mannose, and galactose residues has been demonstrated. The apparent buoyant dentisty (1.340), the sedimentation coefficient (10.7 S), the Stoke's radius (83 A), the partial specific volum (0.707), and the molecular weight (350,000) have been determined. The frictional ratio (flf0 = 1.8) derived from the Stoke's radius indicates that the molecule is asymmetric. The quaternary structure has been examined. Subunits of molecular weight 150,000 and 46,000 have been observed. The latter has electrophoretic properties identical with luciferin or oxyluciferin.

Force breeding, social disorder and mammary tumor formation in CBA/USC mouse colonies: a pilot study

If the newborn of a socially organized CBA/USC mouse colony are regularly removed (force breeding), the social order breaks dowm. There is fighting among the males and the young are lost due to neglect and injury by the females (cronism). A high incidence of mammary tumor formation is observed during the disorder of such formerly socialized groups. In the pilot study being reported, force breeding initiated at the sixth month of colony life eventually at the ninth month led to fighting and the loss of young by cronism. All 12 female colony members developed tumors during the subsequent 5 months. Meanwhile, tumors developed in only 8% of the same age Study Siblings and in 46% of Study Breeders maintained under rapid breeding conditions. Force breeding is a knowm moderately effective tumorigenic technique. Since tumors did not occur in the population cage until its social system broke down, this suggests that the combination of force breeding and social disorder-induced neuroendocrine changes is peculiarly favorable to tumor development.

The induction of acute and chronic cardiovascular disease in animals by psychosocial stimulation

It has been established that sustained emotional arousal can accompany the psychosocial stimulation induced by the social interaction of members of a social group as they compete for desiderata, such as food and water. This paper reviews the evidence that this arousal of neuronendocrine response patterns can, in turn, lead to disease states and to a fatal outcome. Various experimental observations in pigs, monkeys, baboons, tree shrews, and rodents demonstrate both acute and chronic disturbances of cardiovascular function. These conditions can lead to sudden death or to sustained high blood pressure with arteriosclerotic lesions in the heart and blood vessels. It is shown that when social pressure that has been maintained for a sufficiently long period is relieved, the organism does not revert to normal.

A model of psychosocial hypertension showing reversibility and progression of cardiovascular complications

The sequence of pathophysiological changes that can result from the stimulating effects of a sustained disturbance of the social environment was studied in ten colonies of socially deprived mice. Sixteen formerly isolated males were placed with 16 normal females in population cages consisting of seven intercommunicating boxes. Six of these socially disturbed 32-member colonies were terminated after periods of interaction ranging from 2 days to 9 months. The remaining four were terminated a month or more after the males had been returned to individual isolation. Indirect blood pressure measurements, body and heart weights, and sections of hearts and aortas were studied in the males. Following the shorter exposures, blood pressure reverted to normal in a few days. Exposure of 6 months or more were associated with unchanged body weights and sustained increases in heart weight and blood pressure readings. In addition, there was a significant development of aortic arteriosclerosis and myocardial fibrosis. These changes persisted despite prolonged return to isolation.

Impaired atrial receptor responses in dogs with heart failure due to tricuspid insufficiency and pulmonary artery stenosis

In a study of the effects of heart failure on the responses of cardiac receptors, ten dogs were subjected to tricuspid avulsion and pulmonary artery stenosis. One case of spontaneous heart failure was included in the series, and the electrical spike responses of atrial receptors to progressive changes in atrial stretch induced by infusion and hemorrhage were contrasted with those in normal control dogs. In the control dogs, the number of spikes per cycle increased very sharply with moderate, i.e., 5-10 cm H 2 O, venous pressure increments before reaching a maximum at 20 cm H 2 O. In the experimental dogs, the firing rate failed to increase to the same extent despite large increases in pressure. The resulting sets of curves exhibited a sharp dichotomy. This evidence for the impaired response of elements of the subendocardial receptor network is compatible with a decrease in the sensitivity of feedback mechanisms responsible for the regulation of sodium and water metabolism.