Effects of prostaglandins and catecholamines on rat spleen adenylate cyclase in vitro

The results reported here show some characteristics of adenylate cylase (EC 4.6.1.1) derived from homogenates of rat spleen, and describe the in vitro stimulation of this enzyme by prostaglandins, nucleotides, and F- under conditions where cyclic nucleotide degradative pathways are effectively inhibited. Particulate fractions from rat spleen homogenates contain high adenylate cyclase activities, and the highest specific activity is recovered in a particulate fraction prepared by low speed (1200 X g) centrifugation. Activity found in all particulate fractions is stimulated by fluoride, prostaglandins E1 and E2, catecholamines, and purine nucleotides. No stimulation is caused by prostaglandins F1 alpha and F2 alpha. Stimulation by prostaglandin E1 and E2 is augmented by GTP and other purine nucleotides, and stimulation by the combination of GTP and prostaglandin E1 is equal to that caused by optimal fluoride concentrations. Stimulation caused by L-isoproterenol is additive to that caused by GTP but is not increased by GTP.     

Glucose-6-phosphate dehydrogenase in lichen planus skin

The apparent Michaelis constant (Km) for glucose-6-phosphate of the enzyme glucose-6-phosphate dehydrogenase has been measured in extracts prepared from biopsies of normal human skin and from both affected and apparently normal skin of patients with lichen planus. No differences of Km were found and starch gel electrophoresis of extracts from lichen planus lesions and normal controls showed similar patterns when stained for glucose-6-phosphate dehydrogenase activity. These results do not support the view that lichen planus is an inborn error of metabolism in which the structure of glucose-6-phosphate dehydrogenase of skin is affected.     

The Mark IV system for radionuclide computed tomography of the brain

The Mark IV scanning system is a simple four-sided arrangement of 32 independent detectors which rotate continously as a unit, detecting, processing, and displaying the reconstructed data while the study progresses. Detection is by single photon counting and is compatible with commercially available radionuclides. An empirical correction is applied for attenuation, difference in detector response, and scatter. It is a high-sensitivity device with approximately uniform resolution throughout the section plane. There is good reproducibility and accuracy for absolute quantification of radionuclide concentration in the brain. Clinical applications include scans of 99mTcO4, 99mTc-RBC, 123I-iodoantipyrine, 99mTc-diphosphonate, and 111In-DTPA.     

Uterine work in parturition

This paper presents a theoretical analysis relating work expended by the uterus to the synergistic relationship between intrauterine pressure (IUP) and cervical dilatation (CD). By utilizing a geometrical model for the fetal presenting part which is assumed to be in contact with the cervix, the changes in internal volume of the uterus with each contraction can be shown to be functionally related to cervical dilatation. Thus work, expressed in terms of foot-pounds, can be calculated using the integral of pressure times incremental volume. By simulating intrauterine pressure and cervical dilatation with continuous analytical wave forms, the alterations required in uterine work to dilate the cervix are calculated for various wave-form aberrations which are seen in clinical situations. The wave-form aberrations are applied to an elastic cervical model as well as a viscoelastic model. Using the principles of thermodynamics the areas of the fetouterine complex which absorb the work generated by the contractions are defined. It is shown that the efficiency of the contractions to dilate the cervix can be calculated by evaluating the work expended in these various areas of energy absorption. The purpose of this paper is to present the theory upon which clinical findings in obstetrics can be based so that conclusions drawn will be technically sound.     

Zinc contamination and misplaced p-n junctions in InP?GaInPAs d.h. lasers

A serious problem involving the use of Zn in the formation of GaxIn1?xPyAs1?y double-heterostructure lasers is identified. Contamination of epitaxial layer solutions from Zn is shown to result in misplaced p-n junctions in these devices. The improvement in the laser characteristics of devices having correctly placed p-n junctions is demonstrated.     

Effect of coronary thrombus age on fibrinogen uptake

A study was carried out to define the time limits during which an experimental coronary thrombus remains capable of incorporating fibrinogen. 131I-fibrinogen was given to intact anesthetized dogs at different time intervals, up to 67 hours, following the formation of a coronary thrombus by catheter-electrode. Radioactivity of the recovered thrombi as a whole and segmentally divided, was determined following variable time intervals of exposure to circulating fibrinogen and was expressed as thrombus/blood ratio. The results indicate that coronary thrombi formed in a normal coronary vessel remain capable of incorporating fibrinogen for at least eighteen hours, with no significant differences in the segmental distribution of radioactivity. These findings do not support the view that the recovery of isotopic fibrinogen, which was given after the onset of coronary symptoms, in thrombi from patients with myocardial infarction establishes that the thrombus was initiated after the ischemic process.     

Studies on the compositional changes in poppy capsule components during maturation and drying

Terminal and first-lateral capsules of Papaver somniferum L. were dissected on five occasions, starting at the fourth week following 50% flowering. Results showed that moisture contents were highest in the placentae and wall components, lowest in the seed, and intermediate in the stigmata rays, or ‘disc’, and upper stem fractions. Both terminals and laterals lost water rapidly during weeks 4 and 5, but less during weeks 6, 7 and 8. Laterals dried out later than terminals and were not sufficiently dry for storing in bulk at 16% moisture until 2 weeks after the terminals.

Analyses showed that thebaine, codeine and morphine contents of terminals were all greater in the wall than in the placentae, and that the levels in disc or stem were still less. If the seed is discounted, then the capsule wall accounts for around half the total dry matter yield and around two-thirds of the total morphine yield.     

The effect of zinc sulphate and of bicitropeptide on tetracycline absorption

The interaction between tetracyclines and di- and trivalent ions such as are contained in aluminium, magnesium, calcium, iron and zinc-containing salts or complexes or antacids is well documented. The potential for interaction between tetracyclines and zinc and bismuth salts is often not realised, but is emphasised by the findings reported here. The absorption of 250 mg phosphate-potentiated tetracycline hydrochloride was reduced by 75% when administered concurrently with 220 mg zinc sulphate. The absorption of 250 mg phosphate-potentiated tetracycline hydrochloride was reduced by 50% when administered concurrently with 10 ml bicitropeptide, a bismuth-protein complex. Tetracyclines should thus not be administered concurrently with zinc salts or bicitropeptide.     

Fletcher factor deficiency and myocardial infarction

The case of a patient who, while being treated for an acute myocardial infarction, was found to have Fletcher factor deficiency with a Fletcher factor concentration of less than 1% of normal is described. Fletcher factor deficiency is associated with defects in several interrelated systems, including clotting, fibrinolysis and kinin generation, all of which play a role in the pathogenesis and evolution of infarction. The development of myocardial infarction in a patient who had severe Fletcher factor deficiency emphasizes the importance of alternate pathways for activation of these systems.