Giant pigment granules in dermal melanocytes of rat scrotal skin

Summary Giant melanosomes, ellipsoidal (1.5 m×1.3 m) or spherica (1.1 m–1.4 m in diameter) exist in the scrotal skin of the black pelted Long Evans rat. They are longer and wider than normal stage IV melanosomes (0.7 ×0.4 m) found in theses dermal melanocytes.The authors acknowledge with gratitude, the technical assistance of Evelyn Ann Flynn. This work was supported by grant AM 20669-16 from the National Institute of Arthritis, Metabolism, and Digestive Diseases, USPHS.     

Failure of somatostatin to influence experimental tumor cell growth in vivo and in vitro

Summary The influence of somatostatin on tumor cell growth was studied in vivo in mice (sarcoma 180 ascites tumor and Lewis lung tumor) and in vitro on nontransformed and polyoma-transformed cell lines. 4 or 20 g/100 g of cyclic somatostatin and 4 g/100 g of linear protamin Zn-bound somatostatin were injected s.c. twice daily in the in vivo study. Cyclic somatostatin (1, 4 or 10 g/ml) was added twice daily to the cell cultures. Somatostatin administration influenced neither the survival of animals nor the growth rate of cultured cell lines. *** DIRECT SUPPORT *** A2025117 00011     

Dopamine and cerebral cortical blood flow in the rat

Summary Dopamine topically applied to the cerebral cortex (1–20 g/ml) or administered i.v. (0.5–64 g/kg/min) has no effects on cerebral cortical blood flow in the rat.     

The levels of metallothionein-like proteins in animal tissues

Summary The level of metallothionein-like proteins was determined in different tissues of 6 animal species. The highest concentrations were found in pig and rat tissues. The organs richest in metallothionein-like proteins included: kidneys (101–305 g/g), intestine (127–257 g/g) and liver (54–496 g/g).Studies performed under the Polish-American agreement 05-009-2 with National Institute for Occupational Safety and Health, PHS, USA.     

The enhanced induction of metallothionein by zinc,its half-life in the marine fishPleuronectes platessa,and the influence of stress factors on metallothionein levels

Summary Intraperitoneal injection of zinc raised levels of a hepatic metallothionein-like species. Assuming that this species was metallothionein (MT) then levels were raised from approximately 20 g/g to 300 g/g in 7 days, and levels thereafter remained high for the next 4 weeks. The half-lives of the protein in liver and kidney from starved fish, measured using in vivo incorporation of³⁵S cysteine at 11°C, were approximately 27 days and 32 days respectively. The following agents failed to stimulate synthesis of MT in plaice: stress (due to catching), endotoxin, dexamethasone, cortisol and turpentine.     

Il punto nella terminologia matematica greca

Summary In this note we claim that the two words and , which were used in Greece to indicate the geometrical point, had both been introduced in the scientific language in the first half of the IV^th century B.C., and that they became popular independently of each other in two different cultural circles, those of philosophy and of mathematics, respectively.We propose therefore, in contrast to a conjecture by Heiberg, a new explanation for the predominance of during the golden age of Greek mathematics and for the resurgence of during the period of decadence.

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Memoria presentata da A. Seidenberg     

Adrenocortical metabolism and plasma corticosterone in soman intoxicated rabbits

Summary The organophosphate neurotoxin soman produced impairments in adrenocortical RNA and protein metabolism. Fasciculate and reticular cell RNA and protein contents were supporessed with sublethal to acutely lethal dosages (20, 30 and 40 g/kg, s.c.) during the acute excitatory phase of intoxication and at 6–8 h post injection. All three dosages produced ca 90% inactivation of plasma cholinesterase. A transient elevation of plasma corticosterone occurred with 20 g/kg soman whereas there was a protracted increase with 30 g/kg. Corticosterone was not significantly elevated with 40 g/kg, but death occurred at 13±4 min. Thus, the magnitude and/or nature of soman-induced metabolic impairments does not appear to prevent adrenal activation.Supported by US Army Medical Research and Development Command Contract DAMD 17-81-C-1202.     

Repercussions de l'hyperthyroïdie sur le contenu total en ADN du cervelet de rat âgé de 6 et 35 jours. Effets comparés de la LT3 et de la DLT4

Summary The total cerebellar proteins RNA and DNA contents from DLT4- and LT3-treated rats was studied at 6 and 35 days of age. The effect of injections of 5 g/j of DLT4 is comparable to that of 25 g of LT3 at birth, followed by 0.5 g every 2 days. On the other hand, injection of 0.5 g of LT3 every 2 days does not induce any significant modification of the total DNA contents in the cerebellum.     

Antidiuretic effects of oxytocin in the Brattleboro rat

Summary The antidiuretic activity of oxytocin (OT) was measured in Brattleboro rats with congenital diabetes insipidus. A dose dependent antidiuretic response was found in animals receiving chronic infusions of 0.1 g/h, 1.0 g/h, and 5 g/h of OT. OT infused at the rate of 5 g/h over a 7-day period completely reversed the symptoms of diabetes insipidus. The results support the concept that OT serves as a weak agonist of vasopressin at the level of the kidney and at pharmacological levels exhibits antidiuretic activity.     

Preparation of isolated single cardiac cells from adult frog atrial tissue

Summary Isolated cardiac cells from bullforg atrial tissue can be readily prepared by digestion of intact fragments of atrial tissue with trypsin and collagenase. These isolated cells have dimensions of about 5 m in width and range in length from 300 m to over 500 m. Such isolated cells may prove useful for the investigation of contractile activity of cardiac muscle at the single cell level and at the sarcomere level within the single cell.This investigation was supported by U.S. Public Health Service, National Institutes of Health Grant No. HL 12426 and a Kansas Heart Association Grant-in-Aid.We wish to thank Dr.J. Sommers of Duke University Medical Center for doing electron microscopy of the isolated cells to confirm the single cell nature of the preparations.     

Central nicotinic receptor blockade inhibits emotionally conditioned pressor responses in rats

A conditioned stimulus previously paired with electric footshock produced an increase in blood pressure in conscious, freely moving rats. The conditioned pressor response was reproducible. Intracerebroventricular injection of the nicotinic receptor antagonists hexamethonium (1–10 g) or pentolinium (10 g) but not the muscarinic receptor antagonist methylatropine (3 g) produced an inhibition of the conditioned pressor response, whereas intraarterial injection of hexamethonium (10 g) did not affect the response. Intraventricular injection of the cholinesterase inhibitor physostigmine (3–10 g) produced an enhancement of the conditioned pressor response. These results are consistent with the possibility that central nicotinic receptors play a role in the expression of the emotionally conditioned pressor response in rats.     

Relationship between chlorophyll a content and protein content of invertebrate symbioses with algae or chloroplasts

Summary The chlorophyll a and protein contents of invertebrates containing autotrophic symbionts are indices of symbiont and host biomass, respectively, and the chlorophyll a content per unit protein is a good measure of symbiont: host ratio. For three different associations, the chlorophyll a content per unit protein is 0.01–0.02 g g^–1.The hydra andE. viridis were provided by M. H. Christopher and J. R. Turner. I thank Professor D. C. Smith, Dr J. B. Searle and Dr T. A. V. Rees for the valuable comments on drafts of this paper. This work was supported by research grants from S.E.R.C.     

The effect of clomiphene and cyclofenil upon pituitary LH and hypothalamic LH-Releasing-Factor content in the female rat

Zusammenfassung Der Effekt von Clomifenhydrogencitrat und von Cyclofenil auf den LH-Gehalt der Hypophyse und den LH-RF-Gehalt des Hypothalamus wurde an kastrierten, weiblichen Ratten untersucht, die mit Östradiol und Progesteron blockiert worden waren. Während die Injektion von Cyclofenil im Dosisbereich von 100 bis 600 g/Tier zu einem Abfall von sowohl LH als auch LH-RF führte, konnte bei Verabreichung von Clomifen nur bei der Gabe von 25 g/Tier eine signifikante Herabsetzung von LH und LH-RF beobachtet werden.     

The dopamine autoreceptor agonist B-HT 920 markedly stimulates sexual behavior in male rats

Summary B-HT 920, a selective agonist at dopamine (DA) autoreceptors, strongly increased the incidence of penile erections (PE) in male rats, an effect which was dose-related and antagonized by haloperidol. B-HT 920 at 100 and 200 g/kg i.p. significantly altered the copulatory pattern of sexually active male rats, reducing the number of mounts and intromissions as well as the latency to the first ejaculation, a stimulant effect which was confirmed in sluggish males at a dose of 100 g/kg.     

Disruption of mitochondrial function as the basis of the trypanocidal effect of trifluoperazine onTrypanosoma cruzi

Summary The tricyclic anti-calmodulin drug trifluoperazine (TFP) inhibited growth and motility of epimastigotes ofTrypanosoma cruzi, at concentrations lower than 100 M, and motility and infectivity of the bloodstream trypomastigote form at 200 M. Electron microscopy of TFP-treated epimastigotes showed that the major effect was at the mitochondrial level, with gross swelling and disorganization. The oligomycin-sensitive, mitochondrial ATPase was completely inhibited by 20 M TFP, and the same drug concentration caused a 60% decrease in intracellular ATP content. The results suggest that the trypanocidal effect of TFP may be related more to mitochondrial damage than to the well-known anticalmodulin effect of the drug.     

Geminus and the concept of mean motion in Greco-Latin astronomy

Conclusion Geminus account of lunar motion in chapter 18 of hisIntroductio astronomiae is, in our view, an important contribution to Greco-Latin astronomy because, in attempting to reconstruct arithmetically (the parameters of) the Moon's motion in longitude, he undermines the task astronomers had hitherto set for themselves. This undermining of a commonly acknowledged view of the purpose of astronomy is articulated in a whole new set of questions concerning the nature and place of both observation and mathematical reasoning in the science of the heavens. Yet, one must not overlook the fact thatGeminus reconstruction also indicates resources for addressing these questions. Of these resources, the most powerful proved to be the idea that irregular motion could be quantified as a systematic departure from a mean motion, and the idea that observational data could be organized and structured by means of genetic arithmetical reconstructions.But, since we limit our attention to extant treatises and decline to speculate about works or parts of works that have not survived, we must say that it would takePtolemy to discern the new direction for astronomy thatGeminus opened up and to pursue it. In part, this involved straightening out the conflated conception of mean motion in chapter 18 — the qua arithmetic mean daily displacement can only be anapparent lunar motion in longitude and not one the Moonreally makes, but the same need not be true of the qua periodic mean daily displacement — and determining its proper relation to real and apparent planetary motion. Indeed,Ptolemy's genius lay, we think, in seeing that even though, in assimilating Babylonian astronomy, earlier and contemporary Greco-Latin writers betrayed a confused, inconsistent, and unsophisticated grasp of the proper role of arithmetic, geometry, and observation in astronomical argument [seeBowen 1994], the solution lay in a mathematical reconstruction of the observed celestial motions, in which mean motion played an essential role.     

Metal accumulation inAgaricus bisporus: Influence of Cd and Cu on growth and tyrosinase activity

Summary To investigate heavy metal uptake in the common mushroomAgaricus bisporus, commercial cultures of the fungus were exposed to different amounts of copper ad cadmium. In contrast to copper, cadmium already exerted pronounced toxic effects at low concentrations (>10 M) in the compost and concomitantly enhanced the uptake of copper. Tyrosinase activity measured in the fruit bodies increased sharply, when small amounts of Cd (10 M) were added to copper-rich compost. Gel filtration experiments with crude extracts from fruit bodies demonstrated the absence of a low molecular weight metal binding protein.Acknowledgments. This work was supported by the Schweizerischer Nationalfonds grant 3.420–0.78 (to K.L.) and by Hauser Champignonkulturen AG. We are indepted to Dr D. Rast for helpful discussions.     

The length-tension diagram of single muscle fibres of the crayfish

Zusammenfassung An isolierten Muskelfasern vonAstacus fluviatilis wurde mittels Kaliumkontraktur die Spannung-Sarkomerlängenrelation untersucht. Maximale Faserspannung wird bei einer Sarkomerlänge von 10,5 entwickelt. Werden Fasern zu einer Sarkomerlänge von 16,5 gedehnt, so ist die Spannung nicht mehr messbar. Diese Sarkomerlänge ist etwas grösser als diejenige (14.45), die aus der Länge der dicken Filamente (3.95) und der optimalen Länge hervorgeht.     

Storage of irradiated human blood; a source of error in quantitative chromosome analysis

Summary Human whole blood was irradiated with 2.5 Gy of 220 kVp X-rays and stored before culture with 9.7 M BrdU and 19.4 or 38.7 M BrdU for 0, 24, 48 and 72 h. The frequency of dicentrics and ring chromosomes was determined in cells staining as first division (M1) metaphases with the fluorescence plus Giemsa technique. Storage had no influence on the observed aberration yields in 44 h cultures containing 9.7 M BrdU. In 66 h cultures at 19.4 M BrdU the observed yields after 2 and 3 days' storage were significantly lower as compared to cultures from fresh blood. No storage effect was revealed in 66 h cultures containing 38.7 M BrdU. In cases where cytogenetic radiation dosimetry has to be carried out using blood samples which have been in transit for 2–3 days, the findings are of relevance for a correct determination of the chromosome damage in M1 cells.     

Copper utilization during embryogenesis ofPalaemon lamarrei

Summary The pattern of copper utilization during the embryogenesis of the freshwater prawn,Palaemon lamarrei has been described. Throughout the incubation period, lasting for 14 to 16 days, the egg ofP. lamarrei is permeable to salts and against a concentration gradient, it absorbs 11 g of salt from the freshwater medium. Out of this total salt uptake, as much as 0.143 g is due to the absorption of copper. Intake of copper, as a function of incubation time, exhibited a more or less similar trend to that of total salt intake and this can be attributed to the increased synthesis of haemocyanin.