Effect of isoprenaline on dopamine receptors in the rabbit isolated renal artery

Summary The relaxant effects of isoprenaline on rabbit isolated renal artery and aorta were compared. The results suggest that although isoprenaline acts on -adrenoceptors in the aorta it stimulates dopamine receptors in the renal artery.     

Furocaulerpin,a new acetylenic sesquiterpenoid from the green algaCaulerpa prolifera

Summary Furocaulerpin, an acetylenic sesquiterpenoid possessing a furan ring, has been isolated from the marine algaCaulerpa prolifera, and its stereostructure elucidated mainly on the basis of physico-chemical data.This work was carried out in the frame work of the Progetto Finalizzato per l'Oceanografia e i Fondi Marini, CNR, Rome. Thanks are due to the Centro di Metodologie Chimico-Fisiche of the University of Naples (Mr I. Giudicianni) for the determination of PMR-spectra.     

Androgen levels in the rete testis fluid during sexual development

Summary The concentrations of testosterone (T) and 5-dihydrotestosterone were measured in fluid collected from the rete testis of immature and adult rats. The results indicate that adult levels of T are attained in the seminiferous tubules much earlier than in the peripheral circulation.This work was performed at the Worcester Foundation for Experimental Biology, Shrewsbury, Massachusetts, USA and supported by the National Institutes of Health through grants HD12641 and HD12642. We thank Dr B.V. Caldwell for antiserum to testosterone.     

Protein degradation in human T-lymphocytes

Summary Protein from resting or phytohemagglutinin-stimulated human peripheral blood T-lymphocytes, pulse-labeled in vitro for 1 h with³H-leucine, had a half-life of 30 h.     

9-α-hydroxyparthenolide,a novel antitumor sesquiterpene lactone fromAnvillea garcini (Burm.) DC1

Summary A novel sesquiterpene lactone, 9--hydroxyparthenolide (1) was isolated from a chloroform extract ofAnvillea garcini that was collected in Iran. The structure of1 was assigned on the basis of high field NMR decoupling experiments and other spectroscopic evidence. This -methylene lactone has shown significant activity in both the 9KB cell culture and P388 mouse leukemia test systems.The authors acknowledge the support of contract No. N01-CM-97296 from the National Cancer Institute and the use of the Purdue University Biochemical Magnetic Resonance Laboratory (NIH grant No. RR01077). This is paper 16 in the series Potential Antitumor Agents.     

A microanalysis of colloid osmotic pressure

Summary A needle type of colloid osmometer has been devised with special attachments which made it useable with 3-l samples. It has been used in oncometry of fresh water teleosts to give the following results: 5.1±1.0 mm Hg for goldfish, 5.2±0.71 mm Hg for carp, and 14.3±0.75 mm Hg for eel.This study was supported in part by Research Grant 387036 from the Ministry of Education of Japan.invited to National Institute of Physiological Sciences, Okazaki, Japan.     

Studies on muscle fibre splitting in skeletal muscle

Summary Autoradiographic, stereological and histological studies have been carried out to determine the origin of muscle fibre splitting which supposedly occurs during muscle hypertrophy. The results obtained clearly indicate that the supposedly split fibres are a transient response probably derived from satellite cells and are not derived from pre-existing fibres by true splitting. Similarly, increases in muscle fibre size are not achieved by recruitment of satellite structures as indicated by lack of myonuclear recruitment.Acknowledgment. This work was carried out with the aid of a grant from the Medical Research Council of Great Britain. The authors are grateful for the excellent technical assistance of Miss H. Caulton, M.J. Wild and M. Fenner.     

Purification of mouse liver thymidylate synthetase by affinity chromatography using 10-methyl-5,8-dideazafolate as the affinant

Summary Thymidylate synthetase (methylenetetrahydrofolate: 2-deoxyuridine-5-monophosphate C-methyltransferase; EC 2.1.1.45) from neonatal mouse liver has been purified 714-fold by affinity chromatography on aminohexylsepharose bound 10-methyl-5,8-dideazafolate.Supported by grant CA22754, awarded by the National Cancer Institute, DHEW.     

Complete replacement of serum in primary cultures of chick embryo brain cells by growth-promoting alpha-globulin

Summary Growth-promoting alpha-globulin (GPAG), a specific serum protein complex which induces mitotic activity in continually replicating metazoan cells in vitro, was shown in this study to support growth of astrocytes and mesenchymal cells as well as process formation of nerve cells isolated from cerebral hemispheres of chick embryos.     

Conduction velocity of peristaltic waves in the in vivo ureter: application of a new diameter gauge

Summary The conduction velocity of peristaltic movements of the canine ureter was measured under anaesthesia with a new type of diameter gauge using an image sensor. The peristaltic velocity was 34.1±6.2 mm/sec in 10 experiments. Noradrenaline at a low dosage of 1 g/kg i.v. reduced the resting diameter, increased the conduction velocity to 47–56 mm/sec, and approximately doubled the frequency of contraction. The application of acetylcholine also caused an increase in both frequency and conduction velocity (42–46 mm/sec). A plot of the conduction velocity against the mean period of peristaltic contraction was hyperbolic in shape.