Role of granular cells in the placement and distribution of synapses between ascending fibers and Purkinje cells of the rat cerebellum]

The study of rats irradiated during development shows that the establishment of the one-to-one relationship in the adult between climbing fibers and Purkinje cells which follows the immature multiply innervated stage mainly depends on granule cells formed before day 8. Climbing fibers ending upon a multiply innervated cell are intermingled on the same dendritic segments.     

Changes in the level of alpha1-macroglobulin in rats during Masugi nephritis]

Using chromatographic technique on "Sephadex G 200" associated to immunologic qualitative and quantitative techniques, the authors showed that the alpha1-macroglobulin is present in normal Rat urines. This protein is also present in urines obtained during the Masugi nephritis. The alpha1-macroglobulin concentration observed in the different urine samples is unrelated to the total proteinuria evolution. The results given allow us to discuss the mechanisms of the glomerular filtration.     

Characteristic changes of cerebellar proteins associated with cerebellar hypoplasia in jaundiced Gunn rats and the prevention of these by phototherapy

Summary In the cerebellar particulate fractions from Gunn rat homozygotes 3 protein bands with apparent mol.wts of 250,000, 50,000 and 33,000 in SDS-polyacrylamide gel disc electrophoresis underwent major changes, and phototherapy of the newborns could effectively prevent the changes.A part of this research was supported by grants from the Ministry of Education in Japan (No.448131) and the Japan Association for Maternal Welfare.     

Organization in "barrels" of layer-IV cells of the S1 cortex in the mouse: effects of lesions or deprivation of the mystacial vibrissa]

In newborn mice the mystacial pads of the upper lips were submitted to different destructive or functionally reducing procedures. The effects on the barrels of the somato-sensory cortex were judged in mature animals and classified into 3 categories: 1. the barrels were present and normal; 2. the cortex was devoid of barrel structures; 3. the barrels were disorganized. Only procedures which involved peripheral lesions, and not those which reduced only the functional level, produced effects as deep as absence or disorganization of the barrels.     

Desensitization by human chorionic gonadotropin (hCG): demonstration of a negative control of gonadotropin receptors by hCG at the level of testicular Leydig cells]

A single injection of hCG (500 IU) to intact and hypophysectomized prepubertal rat increases plasma testosterone levels and decreases hCG receptors in the testicular Leydig cells for 4 to 5 days. In intact animals testosterone exhibit a rapid increase within hours and a delayed paradoxical increase between 60 and 96 hours. In hypophysectomized animals the first peak is not present. In both intact and hypophysectomized rats hCG receptors are almost undetectable between 10 and 96 hours following hCG injection. Since receptor occupancy cannot account for this phenomenon it is concluded that hCG is exerting a negative control on its own receptors.     

Effect of cobaltous chloride on the blood sugar level and the islet cells in rats

Résumé L'effet de l'administration de chlorure de cobalt chez le rat normal est une hyperglycémie prononcée dans l'espace de quelques heures après l'injection. Il n'est pas possible de déceler des changements dans les cellules des îlots de Langerhans. Les noyaux des cellules ne montrent qu'une diminution faible après 24 h de l'injection.     

Mode of action at the cellular level of new thiopyrimidines with antimitotic properties]

New thiopyrimidine derivatives have been synthesized. Among them, several inhibit the multiplication of Chick embryo cells cultivated in vitro: they provoke strong nucleolar alterations, prevent the cells from entering into mitosis and can give rise to cell polyploidisation as to DNA.     

Production of Friend virus particles at the surface of cells synchronized by Ficoll gradient centrifugation]

Murine cells continuously producing Friend viral complex were synchronized by Ficoll gradient centrifugation. Cells were isolated from different parts of the gradient and counts of budding particles were performed on ultra-thin sections. No significant differences were noticed, suggesting that viral release is not related to cell cycle.     

Variation in the number and size of myelinated nerve fibers regenerated after repeated localized freezing of the sciatic nerve of rats]

The number and size of myelinated fibres have been determined in the nerve to medial head of the gastrocnemius muscle of Rats in which the sciatic nerve had been frozen locally 1 to 5 times at monthly intervals. The contralateral nerve was used as a control. When the measurements were made one month after the last freezing, the number of fibres increased progressively until the 3rd freezing, reaching about 220% of the normal value. No higher values were observed after 4 or 5 freezings. The mean diameter of fibres decreased with the number of operations. When the measurements were made 3, 6, 12 or 18 months after the 3rd freezing, the number of fibres decreased by about 30% between the 1st and the 3rd month and then stabilized. The mean diameter of fibres increased progressively. However, at the 18th month, the size of the myelinated fibres had not reached the normal value.     

Experimental study in rats to reduce carbon monoxide in the blood induced by cigarette smoke, by inhaling oxygen at atmospheric pressure]

When animals are exposed to cigarette smoke, the concentration of carbon monoxide in blood is rapidly increased, so that intensive inhalation tests cannot be carried out. A simple apparatus is described to expose Rats alternatively to cigarette smoke and to oxygen in order to reduce the concentration of carbon monoxide in the blood. This method makes it possible to increase the daily administration of smoke considerably; nevertheless, under such conditions, lung tumors were not observed.     

Modifications in the type distribution of muscle fibers induced by repeated local freezings the rat sciatic nerve]

In the Rat, after a localized freezing of the sciatic nerve inducing a complete denervation of the medial head of the gastrocnemius muscle, the reinnervation took place within 16-18 days under our experimental conditions. After only one freezing, a limited and stable "type-grouping" of muscle fibres is observed from 30 to 360 days. After 2 to 5 freezing repeated every three weeks, the muscular changes observed one month after the last freezing are much more pronounced than when only one freezing is performed. These changes consist of a progressive increase in the number of type I and type II C fibres. This transformation is not stable: 3 months after the 3rd freezing, the muscle pattern does not differ from that which is noted after a single freezing.     

On the mechanism of radiosensitization by iodine compounds at the molecular level

Riassunto L'alcool deidrogenasi del lievito irradiata con raggi X in soluzioni contenenti ioduro di sodio, acido 3-iodopropionico o ioduro di metile, è inattivata con un rendimento più elevato che in assenza di tali sostanze. L'effetto sensibilizzante dello ioduro di sodio e dell'acido iodopropionico è proporzionale alla loro concentrazione nell'ambito di 0–16 molecole di essi per molecola di enzima. L'alcool deidrogenasi irradiata in presenza di ioduro di sodio marcato con I¹³¹ non rivela la presenza di iodio legato alla sua molecola.     

Stimulation of the secretion of LH and FSH and increase in testicular weight at birth in rats]

The evolutions of serum LH and FSH concentrations and of testicular weight have been measured in the newborn Rat before, during and up to 24 hrs. after birth. A sudden and transient increase of LH and FSH is observed at birth. The testicular weight rises rapidly between 2 and 4 hrs.     

An hypothesis for the process of selection at the subcellular level leading to the appearance of new clones]

According to the hypothesis we propose, the stimulation of one lymphocyte by an antigen induces the simultaneous expression of a great diversity of immunoglobulins of different specificities. Each molecular species is associated with the corresponding mRNA within a subcellular structure: the ergastoplasmic cisterna. It has been shown that in some responding lymphocytes at an early stage of the immune response a few such cisternae are loaded with antibodies while most of the cisternae are synthesizing non specific immunoglobulins. The main point of our proposal is that the selective action of antigen bears on these cisternae and that the mRNA corresponding to the immunoglobulins fitting best to the antigen is transcribed to DNA which is then inserted into the genome. This cell and its progeny become thereafter a monospecific clone submitted to regulation as an element of the network.