High altitude influence on the level and turn-over time of cardiac norepinephrine in rats

Summary In rats exposed to an altitude, of 2,900 meters the level of endogenous cardiac norepinephrine decreases after the 5th day of exposure. The turner-over time of the amine proceeds in 3 steps which are probablyrelated to periods of stress and adaptation: initial increase, important decrease from the 5th day and return to a normal value from the 12 th day.     

Sexual differences in the development of plasma thyroxine levels in the embryo and young chick]

Plasma thyroxine (T4) levels were separately ascertained in male and female embryo and young chicken from the 12th day of incubation till the 4th day after hatching by the thyroxine binding globulin technique. In both sexes, plasma T4 reach a peak the 20th day of incubation, but values are significantly higher in females. A sharp decrease occurred thereafter, plasma T4 tending toward adult values the 4th day after hatching.     

Electrophoretic profiles of proteins and glycoproteins of chick embryo fibroblasts during development]

The variations of proteins and glycoproteins of Chick embryo fibroblasts are studied during development. This investigation is carried out using polyacrylamide disc gel electrophoresis in SDS. Two glycoproteins of high apparent molecular weight (250,000 and 200,000) undergo quantitative modification: they increase from the 8th to 12th day of development and then remain unchanged to the 16th day. They are cell surface components as suggested by fluorescamine labelling and trypsin sensitivity. The results are discussed in terms of relationship between tumor- and embryo cells.     

Moult inhibition in the insectDysdercus cingulatus (Insecta: Heteroptera) by the cerebral glands of the millipedeJonespeltis splendidus (Myriapoda,Diplopoda)

Summary Implantation of 2 pairs of cerebral glands of the diplopodJonespeltis into the newly-moulted 4th or 5th instar nymphs of the insectDysdercus delayed the moulting of these insects for a fairly long time. Implantation of cerebral glands into 1-day old 5th instars postponed the subsequent moult for a shorter period, whereas implantation of cerebral glands into 2-day old 5th instars had no effect. These observations suggested that a neurosecretory factor from the cerebral glands inhibited moulting in this insect, and in the case of 5th instar nymphs there was a critical period before which implanted glands were effective in moult inhibition.Acknowledgments. Prof. V.K.K. Prabhu is thanked for suggesting the topic and for guidance. The University of Kerala is thanked for the fellowship awarded. The laboratory facilities afforded are also gratefully acknowledged.     

Autoradiographic study of proliferative activity and cell migration in the adrenal cortex in fetal and neonatal rats]

On the 20th day of fetal life the cell proliferation is higher in the zona glomerulosa. The fate of marked cells in each cell compartment shows centripetal migration. Their displacement, from the 20th day of pregnancy up to five days post-partum, while at that time the adrenal growth is slowered down, suggests a real migration.     

Demonstration of a basal lamina in cocultures of thyroid cells and embryonal swine skin cells]

Porcine thyroid and embryo skin cells were isolated and cultured. Cultures from each kind of cells, as well as cocultures were fixed twice a week for electron microscopy. On day 8th a basal lamina like material appears only in the cocultures, along the basal plasmalemma of the reassociated thyroid cells. This amorphous material increases up to day 17th.     

Estrogenic inhibition of testicular growth by R2858 in preweanling rats

Daily injections of physiologic doses of R2858 into preweanling rats from the 10th to the 19th day of age resulted in reduced testicular growth compared to controls. Body weights and other organ weights were unaffected. Leydig cells were smaller and less numerous, and showed distinct changes in ultrastructural morphology. Results of this study suggest that alpha-fetoprotein permits normal testicular development during postnatal life.     

Ontogenetic analysis of the theta rhythm during paradoxical sleep in rats]

In the rat, an ontogenetic study of theta rhythm during paradoxical sleep shows a clear evolution between the 14th and the 30th postnatal day. During this period, its mean frequency increases from 5 to 7 cycles per second, and its spectrum shows significant changes. These parameters (mean frequency and spectral components) of the theta rhythm could be a useful index of brain maturation in the rat.     

Development of thermoregulation in the newborn lesser bushbaby (Galago senegalensis moholi,Smith 1839)

Summary The temperature-regulating system in bushbabies operates from the 1st day of life. The postnatal metabolism decreases from the 5th (2.9 ml O₂/g·h) to the 140th day (0.7 ml O₂/g·h) to the level of the adults.This work was undertaken with the aid of the Deutsche Forschungsgemeinschaft and Prof. Dr. E.Kulzer.     

Permissivity of the rat (Rattus rattus) of Guadeloupe with regard to Schistosoma mansoni and evidence for migration of adult schistosomes to the lungs]

In contrast to the laboratory Rat, the Rat (Rattus rattus) of Guadeloupe is a favorable host for the life cycle of S. mansoni: the parasite population is maintained at a high level (between 8 and 16% in this host until the 16th week and reproduces normally). The evolution of the parasitose is marked, shortly after the 8th week, by a transfer of schistosomes from the liver to the lungs.     

The Work of Tschirnhaus, La Hire and Leibniz on Catacaustics and the Birth of the Envelopes of Lines in the 17th Century

The aim of this paper is to examine the work of Tschirnhaus, La Hire and Leibniz on the theory of caustics, a subject whose history is closely linked to geometrical optics. The curves in question were examined by the most eminent mathematicians of the 17th century such as Huygens, Barrow and Newton and were subsequently studied analytically from the time of Tschirnhaus until the 19th century.Leibniz was interested in caustics and the subject probably inspired him in his discovery of the concept of envelopes of lines.     

Developmental characteristics of histamine methyltransferase and phenylethanolamine-N-methyltransferase of rat brain

Summary The specific activity of histamine methyltransferase of rat brain increases rapidly from the 16th until the 25th day of gestation (7 days after birth). The specific activity of phenylethanolamine-N-methyl-transferase shows a rapid incrase during the 1st and the 2nd week after birth, the adult values being obtained by the end of the 2nd week.     

The role of orientation experiments in discovering mechanisms

Many types of experiments have been recognized in the literature. One important type we discuss in this article is the orientation experiment. While orientation experiments are like other types of experiments in that they are tests for causal relevance, they also have other qualities. One important (but not the only) goal of these experiments is to offer a rough, qualitative characterization of the mechanism responsible for a capacity of interest, effectively constraining future research. This makes them particularly useful during the early stages of investigation, when an explanandum-phenomenon has just been identified and several (often competing) hypotheses as to the qualitative character of the mechanism responsible for it are proposed. We illustrate our claims, and explicate a number of additional aims that orientation experiments can sometimes serve, by considering three case studies from different era's, namely the discovery of the mechanisms responsible for i) the capacity of eels to produce numbing sensations (17th and 18th century), ii) puerperal fever in Semmelweis' Vienna Maternity Hospital (19th century), and iii) the capacity of pigeons to home (20th century).     

A rediscovery of scientific collections as material heritage? The case of university collections in Germany

The purpose of this article is twofold: on the one hand, we present the outlines of a history of university collections in Germany. On the other hand, we discuss this history as a case study of the changing attitudes of the sciences towards their material heritage. Based on data from 1094 German university collections, we distinguish three periods that are by no means homogeneous but offer a helpful starting point for a discussion of the entangled institutional and epistemic factors in the history of university collections. In the 19th century, university collections were institutionalized and widely recognized as indispensable in research and teaching. During the 20th century, university collection became increasingly marginalized both on an institutional and theoretical level. Towards the end of the 20th century, the situation of university collections improved partly because of their reconsideration as material heritage.     

Die teratogene Wirkung von Äthylharnstoff und Nitrit bei Ratten

Summary Simultaneous peroral application of ethylurea and sodium nitrite to pregnant Sprague-Dawley rats, on the 9th and 10th days of gestation, causes embryotoxic and/or teratogenic effects. Each substance alone does not afflict the fetuses, whereas the combined addition to the food permits the formation of ethyl nitroso-urea in the digestive tract. The latter readily passes the placenta and develops the teratogenic effect. It is to be considered that teratogenic substances can occur from food constituents in the human organism also.     

Glutathione peroxidase in erythrocytes and plasma of rats during pregnancy and lactation

Summary The glutathione peroxidase activity in the plasma of rats on the 20th day of pregnancy was found to be 50% lower than in nulliparous control animals. During lactation, the level rose again but was still significantly different from that of the control rats on the 20th day post partum. The erythrocyte enzyme activity remained unchanged.Acknowledgments. We should like to thank Dr A. Wendel, Physiologisches Institut der Universität Tübingen, for his advice on carrying out the glutathione peroxidase assay.     

The sedative effects of nicotinamide on gerbil wheel-running activity

Summary The activity of 5 groups of gerbils was monitored over 22 days. 3 of the groups received daily injections of nicotinamide (125, 250 or 500 mg/kg) and a 4th group received saline. The 5th group was untreated. The results indicated that both the 250 and 500 mg/kg nicotinamide administrations greatly reduced the activity levels of the gerbils.This work was supported in part by Faculty Research Grant No. 82-6209 from the University of Alabama in Birmingham to J.M.B.     

Reversible impairment of hepatobiliary function induced by streptozotocin in the rat

The effect of streptozotocin (SZ) on hepatobiliary function was studied in rats on the 1st, 7th and 15th days of treatment. Serum glucose increased significantly on the 1st day, and then remained high. Bile flow, bile acids output and BSP biliary excretion were significantly decreased on the 1st day of treatment, whereas serum sorbitol dehydrogenase was increased. All the parameters tested apart from serum glucose tended to normalize with time. The results suggested a transient toxic effect of SZ on the hepatocyte.     

酶消化结合组织块培养法用于颞下颌关节盘组织工程细胞扩增的初步研究

目的采用酶消化结合组织块培养法对山羊颞下颌关节（temporomandibular joint，TMJ）盘细胞进行体外培养和扩增，探索TMJ关节盘细胞体外培养及扩增的新方法。方法在无菌条件下，切取一月龄山羊TMJ关节盘，剪至1．0mm^3的碎块，用0．25％胰酶、0．01％I型胶原酶消化关节盘组织块，将消化好的组织块置入6孔板中培养。在倒置显微镜下连续观察细胞的形态变化及贴壁率，甲苯胺蓝染色、I型胶原免疫组化染色进行细胞鉴定，测定其生长曲线。结果原代培养的关节盘纤维软骨细胞4天可观察到贴壁细胞，7天贴壁细胞逐渐增多，第10天时细胞彼此相连，铺满平底，细胞以梭形为主，部分多角形。传代后12小时贴壁率达90％，大部分为多角形，4～5天即可长满瓶底。甲苯胺蓝染色可见异染颗粒，胶原免疫纽化染色胞浆内可见棕黄色颗粒。结论酶消化结合组织块培养法培养的山羊TMJ关节盘细胞具有较强的增殖能力，可作为TMJ关节盘组织工程中获取大量原代细胞的实用方法。     

More on the need for circadian,circaseptan and circannual optimization of cyclosporine therapy

Summary Cyclosporine chronotherapy of pancreas-allotransplanted rats revealed, beyond a circadian stage-dependence of equal daily doses, further gain in graft function from doses varying from day to day with an about 7-day periodicity, the first highest dose being given on the 3rd or 5th day after surgery.