Inhibition of phorbol myristate acetate and phytohemagglutinin stimulation of human lymphocytes by 13-cis-retinoic acid and ethyl etrinoate

Summary The retinol analogues 13-cis-retinoic acid and ethyl etrinoate inhibit the mitogenic activity of phorbol myristate acetate and phytohemagglutinin on human lymphocytes. This inhibitory effect is greater against the stimulation with phorbol myristate acetate than with phytohemagglutinin.This work was supported by a grant from the National Cancer Institute of Canada. We would like to thank Hoffmann-La Roche, Canada, for providing the 13-cis-retinoic acid and the ethyl etrinoate.     

Protein digestion in the sea gooseberryPleurobranchia bachei A. Agassiz (Ctenophora: Tentaculata)

Summary Peaks of proteolytic activity of pharyngeal juice occur at pH 5.75 and pH 7.5. The proteases responsible for digestion include a tryptic alkaline protease and a thiol-activated acid protease which is probably cathepsin B. Levels of proteolytic activity parallel those of other carnivorous invertebrates which feed on zooplankton.This study was supported by operating grants from the National Research Council of Canada.We are grateful to Betsy Sweeney for her technical assistance.     

Effect of benzimidazole on nicotinamide adenine dinucleotide phosphate phosphomonosterase activity in wheat leaves

Summary Nicotinamide adenine dinucleotide phosphate phosphomonoesterase was isolated and partially purified from wheat (Triticum aestivum L. var. Selkirk) leaves. The enzyme hadK _NADP value of 1.4×10^–4 M and a pH optimum of 5.9.In vitro activity of this enzyme was unaffected by precursors of NAD (nicotinamide and nicotinic acid) or cytokinis (kinetin and benzimidazole). However, when detached wheat leaves were treated with solutions of these compounds, the precursors lowered the specific activity while the cytokinins enhanced the activity. It is suggested that spatial separation and compartmentation of the enzyme and its substrate NADP account for the similar effect of benzimidazole on both.This work was supported by a grant No. A2698 from the National Research Council, Canada.     

Properties of a calcium-dependent apyrase in the saliva of the blood-feeding bug,Rhodnius prolixus

Summary The saliva of the blood-feeding bugRhodnius prolixus contains at least 11 proteins, and has Ca²⁺-dependent apyrase activity. The activity has a broad pH optimum between pH 7 and 9, and is inhibited by Mg²⁺. Polyacrylamide gel electrophoresis and gel filtration suggest the possibility of at least 2 enzymes responsible for the activity.This work was supported by the National Science and Engineering Research Council of Canada. We are grateful to D. F. Mettrick for use of equipment, and to R. Hewson for invaluable assistance.     

Nicotine and ascorbic acid effects on cold-restraint ulcers in rats

Summary Rats were orally administered 1-ascorbic acid, nicotine, 1-ascorbic acid and nicotine, or distilled water for 10 days. Following this treatment they were fasted for 24 h and then restrained in a cold environment for 2h. Nicotine alone produced significantly more gastric ulcers than any other treatment. 1-Ascorbic acid increased ulceration relative to controls. The combined effects of 1-ascorbic acid and nicotine resulted in reduced ulcer incidence and severity. It appears that 1-ascorbic acid and nicotine do not act synergistically to augment stress-induced gastric ulcer. Supported by Natural Sciences and Engineering Research Council of Canada grant No. A 6312.     

Induction of deoxyribonucleic acid degradation inEscherichia coli by ozone

Summary Cell survival and deoxyribonucleic acid (DNA) degradation were measured for wild-typeEscherichia coli B251 cells after exposure to different concentrations of ozone. The results show that extensive breakdown of DNA occurs after ozonation and that the extent of ozone-induced DNA degradation generally correlates with the colony-forming ability of the cells.We thank Dr M.J. d'Aoust for supplying laboratory facilities. This work was jointly sponsored by the National Research Council of Canada, the Ministère de l'Education du Québec, and funds from the Université de Montréal. One of us (C.H.) acknowledges a postgraduate scholarship from the NRC of Canada.     

Apparent arylsulfatase A activity in excretory fluids

Summary Arylsulfatase activity has been demonstrated in rat and human parotid and submandibular saliva indicating that oral bacteria are not the only source of salivary sulfatase activity. Activity was also observed in human sweat, tears and in snake venom.Acknowledgments. We extent appreciation to Drs.C. Dawes andK. Abe for assistance in saliva collection, to Dr.K. W. Stewart who provided fresh snake venoms and to Dr.E. T. Pritchard in whose laboratory this study was conducted. Supported by grant Nr. MT 3536 from MRC of Canada.     

Opposite effects of one and three injections of cortisone or thyroxine on intestinal lactase activity in suckling mice

Summary A single injection of cortisone or thyroxine to 8-day-old suckling mice initiates a temporary decrease of lactase activity. On the contrary, 3 injections of cortisone or thyroxine provoke a significant increase of lactase activity. It appears that the mechanism which controls the postnatal development of lactase in suckling animals is more complex than expected.Supported by grant MA-5969 from the Medical Research Council of Canada to D. M. C. M. is a recipient of a studentship from MRC of Canada.     

Effects of cortisone and thyroxine on intestinal trehalase activity in infant mouse

Summary Cortisone acetate (25 g/g b.wt/day) administration to 8-day-old suckling mice induces a premature increase of trehalase activity along the entire small intestine. On the other hand, thyroxine (1 g/g b.wt/day) is unable to provoke a precocious increase of trehalase activity. Trehalase appears to be the only brush border membrane disaccharidase controlled solely by glucocorticoid hormones during the postnatal maturation of the intestine.Supported by grant MA-5969 from the Medical Research Council of Canada to D.M. C.M. is a recipient of a studentship from MRC of Canada.     

Relationship of ornithine decarboxylase activity to HCG induced androgen production by rabbit testis

Summary In the rabbit testicular ornithine decarboxylase activity and androgen content as well as serum androgens were increased 4 h after the injection of HCG. D,L-a-difluoromethylornithine (a-DFMO) alone or together with HCG inhibited enzyme activity although testicular and serum androgens were significantly increased aftera-DFMO and HCG. These data suggest that ODC activity is not required for testicular androgen production.This work was supported by the Medical Research Council of Canada, MT 4192.     

The effect of dietary amino acids on the growth of tumors

Summary In C3H mice, a direct dose response relationship between tumor growth and dietary amino acid is seen for fibrosarcoma and mammary carcinoma, extending over a range the lower limit of which is defined by the minimum amino acid requirements, and the upper limit by the amino acid level found in most stock diets.Supported by Medical Research Council of Canada.     

Effects of precocene II and juvenile hormone III on the activity of neurosecretory A-cells inOncopeltus fasciatus

Summary Application of precocene II, topically or by contact method, appears to inhibit the synthetic activity of neurosecretory A-cells of the pars intercerebralis ofOncopeltus fasciatus. Treatment of precocene-treated insects with JH III apparently stimulates the secretory activity of these cells.Supported by National Research Council of Canada grant No. A4669.We thank Dr G. B. Staal, Zoecon Corporation, Palo Alto, California, for the gift of precocene II.     

Effects of a mammalian cholesterol biosynthesis inhibitor on adipocyte ultrastructure and metamorphosis inRhodnius prolixus (Hemiptera)

Summary A potent inhibitor of cholesterol biosynthesis in rodents [BMVA; 5-(4-biphenylyl)-3-methylvaleric acid] inhibits metamorphosis of 4th stage larvae of the blood-sucking bugRhodnius prolixus.This work was supported in part by grants from the National Research Council of Canada awarded to Warner-Lambert Research Institute, Mississauga, Ontario.     

Electrical impedance of daminozide- and calcium-treated McIntosh apples

Summary Daminozide [butanedioc acid mono-(2-2-dimethylhydrazide)] applied in the field reduced the electrical impedance of McIntosh apple fruit at harvest and after storage. Vacuum infiltration with calcium chloride (CaCl₂) increased the impedance whether fruit were treated with daminozide or not.Acknowledgment. This investigation was supported by the National Research Council, Canada, and the Ontario Ministry of Agriculture and Food.     

N-(5′-Phosphopyridoxyl)-4-aminobutyric acid: a stable bisubstrate adduct inhibitor of rat brain 4-aminobutyric acid aminotransferase

Summary N-(5-Phosphopyridoxyl)-4-aminobutyric acid, a stable adduct of pyridoxal phosphate and 4-aminobutyric acid, has been shown to be a potent inhibitor of rat brain 4-aminobutyric acid aminotransferase (GABA-T) with a K_i of 1.4 M.Acknowledgments. This work was supported in part by the United Parkinson Foundation, l'Association Canadienne l'Ataxie de Friedreich, and the Medical Research Council of Canada.     

The presence of β-phenylethylamine,p-tyramine,m-tyramine and tryptamine in ganglia and foot muscle of the garden snail (Helix aspersa)

Summary The concentrations of -phenylethylamine,p-tyramine,m-tyramine,m-octopamine and tryptamine in the ganglia or foot muscle ofHelix aspersa range from <0.6 to 11 ng/g.p-Octopamine levels are higher in ganglia (327 ng/g) than in foot muscle (4.1 ng/g). Dopamine and 5-hydroxytryptamine range from 840 to 2710 ng/g while their acid metabolites, 3,4-dihydroxyphenylacetic acid, 3-methoxy-4-hydroxyphenylacetic acid and 5-hydroxyindoleacetic acid range from <20 to 130 ng/g.Acknowledgments. We thank Dr A.A. Boulton for helpful discus sion, Dr D.A. Durden for supervising the mass spectrometric analyses, Dr B.A. Davis for the synthesis of the deuterated standards, G.H. Wheatley, E.P. Zarycki and M. Mizuno for expert technical assistance, and Saskatchewan Health and the MRC of Canada for providing financial support.     

Effect of norepinephrine and vasopressin on carotid sinus baroreceptor activity in the anesthetized rabbit

Summary Norepinephrine (NE) 10^–6 M or vasopressin (VP) 12.5 U/ml were injected into the isolated carotid sinus of anesthetized rabbits. The sinus was exposed either to the arterial pressure or to a pressure controlled reservoir. Multifiber and single fiber recordings were made. Both NE and VP increased baroreceptor activity at all sinus pressures but decreased activity in a few fibers. The results are consistent with the drugs having their effects on smooth muscle fibers in the adventitia.Acknowledgments. This work was supported by grants from the Medical Research Council of Canada and the B.C. Heart Foundation. The authors are grateful to J. Sharp and D. Morton for their excellent assistance.     

Model systems demonstrating the volatile mutagenicity and carcinogenicity of sodium nitrite in rats

Summary Volatile mutagens derived from sodium nitrite buffered at various pH values or in the presence of human feces were detected using AmesSalmonella tester strain TA 1535 on petrie plates inverted over samples. Volatile mutagenicity increased as the pH decreased and was primarily a function of the nitrous acid produced from sodium nitrite and hydrogen ions. Sodium nitrite administered intracecally to 3 Wistar rats through surgically implanted cannula caused tumors (fibrosarcoma: 1/3 and squamous cell, 2/3). The possible role of nitrite-derived mutagens in GI cancer is discussed.The authors are grateful to Dr A. Carl MacDonald of the Dept. of Surgery, Dalhousie University for his advice and encouragement in this project.This work was supported by the National Cancer Institute of Canada.     

Effect of the juvenoid methoprene on the hemolymph composition of the cabbage maggotDelia radicum (Diptera: Anthomyiidae)

Summary Treatment of post-feeding larvae of the cabbage maggotDelia radicum with methoprene did not affect the capacity of the insect to pupate, but suppressed eclosion to the adult stage. The concentration of hemolymph trehalose was significantly decreased by methoprene treatment, although hemolymph protein and amino nitrogen levels were unaffected.19 December 1986The authors are grateful to D. C. Read of the Research Centre, Agriculture Canada, Charlottetown, P.E.I., Canada for supplying eggs ofD. radicum for the stock colony. TheD. radicum colony was maintained at the Agriculture Canada Research Station, St. John's West, Newfoundland, Canada. The sample of methoprene was donated by Zoecon Corp., Palo Alto, California, U.S.A. This research was supported by a grant from the Natural Sciences and Engineering Research Council of Canada (Operating grant A6679).     

Small lymphocyte production and lymphoid cell proliferation in mouse bone marrow

Summary In mice given³H-thymidine systemically during temporary circulatory occlusion of one hind limb, comparison of the labeling of rapidly-renewing small lymphocytes in the tibial marrows demonstrated that these cells were locally produced. Labeling by³H-thymidine infusion revealed that many marrow large lymphoid cells, presumptive small lymphocyte progenitors, had a marked proliferative activity and rapid turnover which varied according to cell size, was maximal in young mice and declined with increasing age.This work was supported by a grant from the Medical Research Council of Canada. The technical assistance of Mrs E. D. Watson is acknowledged.