Parathyroid hormone stimulates adenylate cyclase in rat cerebral microvessels

We have studied the effect of parathyroid hormone (PTH) on adenylate cyclase of microvessels isolated from rat cerebral cortex. Native bovine (b) PTH-(1-84), the synthetic amino-terminal fragment bPTH-(1-34) and the synthetic analog [Nle8,Nle18,Tyr34]-bPTH- (1-34) amide stimulated adenylate cyclase in a dose-dependent manner with apparent ED50 values of 16 nM, 6.3 nM and 15 nM respectively. The stimulation by bPTH was greatly enhanced by guanosine triphosphate. The PTH antagonist, [Nle8,Nle18,Tyr34]-bPTH-(3-34) amide inhibited the action of bPTH-(1-84) and bPTH-(1-34). In summary, PTH stimulated adenylate cyclase in rat cerebral microvessels in a very similar manner to its stimulation in the renal cortex.

An evaluation of falls, syncope, and dizziness by prolonged ambulatory cardiographic monitoring in a geriatric institutional setting

Fifty-nine patients living in a geriatric residential setting underwent prolonged ambulatory cardiographic monitoring with the Holter monitor (AHM) as part of an investigation of falls, dizziness, and syncope. In 16 instances, cardiac arrhythmias were a contributing factor; in 12, the diagnostic AHM recordings were associated with unrevealing standard electrocardiographic (ECG) tracings. In 12 patients who had fallen, cardiac arrhythmias played a contributing role, but in only two of these cases was the ECG diagnostic. The value of the AHM for use in managing elderly patients, whose cardiac complaints may be vague, and especially in managing those who have sustained falls, is emphasized.

Diet and vitamin nutrition of the high esophageal cancer risk population in Linxian, China

In order to examine the nutritional status of the population of Linxian (in Henan, China) known to be at high risk for esophageal cancer (EC), we analyzed blood samples and conducted 3-day dietary surveys on 3 groups of normal adults, age 40-50, from Henan province. Two groups were from Linxian, where the EC mortality rate is about 138/100,000 (Group C, consisting of volunteers with a family history of EC, and Group NC, consisting of those who did not have a family history of EC). The third group, Group F, was from Fanxian, where the EC mortality rate is about 24/100,000. The average plasma retinol level was found to be about 0.27 micrograms/ml in all 3 groups; about 13%-20% of the individuals had a level less than 0.2 micrograms/ml. The average plasma carotene level of all 3 groups appeared to be adequate, ranging from 0.5-1.0 micrograms/ml. About 23% of the subjects in both Groups C and NC had low (less than 2 micrograms/ml) plasma ascorbate levels; in Group F, 16% had low ascorbate levels. Less than 12% of the individuals in each of the 3 groups had erythrocyte glutathione reductase activation coefficients less than 1.2, indicating a widely occurring riboflavin deficiency. Consumption of alcoholic beverages was not found to be a contributing factor to EC. The results of the present study reveal a deficiency of vitamins in the study populations, but do not indicate that the average nutritional status of the volunteers in Group C was worse than that of Groups NC and F with regard to vitamin A, ascorbate, and riboflavin.

Cognitive style and lateral eye movements

The lateral eye movement paradigm was employed to test the hypothesis that narrow categorizers, who are believed to be more analytic in information processing, make characteristic use of the left hemisphere, while broad categorizers, being more holistic, depend more on the right hemisphere. Data for narrow categorizers confirmed the hypothesis in that they tended to produce a majority of right shifts. Results from broad categorizers turned out to be less clear, although there was a tendency in the direction of left eye shift. Additionally, narrow categorizers made significantly more total LEMs than did broad categorizers. The results are discussed in terms of cerebral specialization underlying cognitive style.

Application of Linear and Nonlinear Graphs in Structural Synthesis of Kinematic Chains

Using graph theory and Polya’s theory of counting, the present paper performs structural synthesis and analysis of planar and three-dimensional kinematic chains. The Section 2 of the paper develops a mathematical model that permits one to perform structural analysis and synthesis of planar kinematic chains with kinematic elements such as revolute pairs, cam pairs, springs, belt-pulley, piston-cylinder, and gears. The theory developed is applied to enumerate eight-link kinematic chains with these kinematic elements. The Section 3 of the paper develops a mathematical model that permits one to perform structural analysis and synthesis of multi-loop spatial kinematic chains with higher and lower kinematic pairs. The theory developed is applied to enumerate all possible two-loop kinematic chains with or without general constraints.

Biosynthesis of 4-aminobenzoate in Escherichia coli

Two different mutations (pabA and pabB) affecting 4-aminobenzoate biosynthesis were obtained in strains of Escherichia coli lacking chorismate mutase and anthranilate synthetase activity, thus allowing study of the pathway of biosynthesis of 4-aminobenzoate by use of cell extracts of strains carrying the pab mutations. Two components with approximate molecular weights of 9,000 (component A) and 48,000 (component B) are concerned in the biosynthesis of 4-aminobenzoate from chorismate by E. coli. No diffusible intermediate compound could be detected.

The biogenesis of mitochondria. II. The influence of medium composition on the cytology of anaerobically grown Saccharomyces cerevisiae

Yeast cells grown anaerobically have been shown to vary in their ultrastructure and absorption spectrum depending upon the composition of the growth medium. The changes observed in the anaerobically grown cells are governed by the availability of unsaturated fatty acids and ergosterol and a catabolite or glucose repression. All the cells contain nuclear and plasma membranes, but the extent of the occurrence of vacuolar and mitochondrial membranes varies greatly with the growth conditions. Cells grown anaerobically on the least nutritive medium, composed of 0.5% Difco yeast extract-5% glucose-inorganic salts (YE-G), appear to contain little vacuolar membrane and no clearly recognizable mitochondrial profiles. Cells grown anaerobically on the YE-G medium supplemented with Tween 80 and ergosterol contain clearly recognizable vacuolar membrane and some mitochondrial profiles, albeit rather poorly defined. Cells grown on YE-G medium supplemented only with Tween 80 are characterized by the presence of large amounts of cytoplasmic membrane in addition to vacuolar membrane and perhaps some primitive mitochondrial profiles. When galactose replaces glucose as the major carbon source in the medium, the mitochondrial profiles within the cytoplasm become more clearly recognizable and their number increases. In aerobically grown cells, the catabolite repression also operates to reduce the total number of mitochondrial profiles. The possibility is discussed that cells grown anaerobically on the YE-G medium may not contain mitochondrial membrane and, therefore, that such cells, on aeration, form mitochondrial membrane from nonmitochondrial sources. A wide variety of absorption compounds is observed in anaerobically grown cells which do not correspond to any of the classical aerobic yeast cytochromes. The number and relative proportions of these anaerobic compounds depend upon the composition of the growth medium, the most complex spectrum being found in cells grown in the absence of lipid supplements.

Genetic analysis of mutant strains of Escherichia coli requiring p-aminobenzoic acid for growth

Mutant strains of Escherichia coli K-12 which required p-aminobenzoic acid for growth were isolated. The mutations were mapped by conjugation and by transduction, and two genes concerned with the biosynthesis of p-aminobenzoic acid were identified.