The roles of phosphorus deficiency and low food intake in the preservation of renal function in uraemic rats

Summary While a diet deficient in phosphorus has a protective effect against kidney deterioration in uraemic rats, this effect, in fact, is more closely related to the reduction of food intake than tho the phosphorus load itself, even though the latter influenced the pattern of the renal lesions.Acknowledgment. This work was in part supported by a grant from the Association pour l'Utilisation du Rein Artificiel (AURA, Paris).     

Location of allatostatic centers in the pars lateralis regions of the brain of the Colorado potato beetle

Summary Selective lesions in the pars intercerebralis and pars lateralis areas of the brain of the adult Colorado potato beetle were produced by radiofrequency cautery. The effect of these lesions on the corpus allatum activity, determined by the short-term in vitro radiochemical assay, revealed that gland inhibitory centers are located in the pars lateralis.     

Metallothionein expression in the central nervous system of multiple sclerosis patients

Multiple sclerosis (MS) is a major chronic demyelinating and inflammatory disease of the central nervous system (CNS) in which oxidative stress likely plays a pathogenic role in the development of myelin and neuronal damage. Metallothioneins (MTs) are antioxidant proteins induced in the CNS by tissue injury, stress and some neurodegenerative diseases, which have been postulated to play a neuroprotective role. In fact, MT-I+II-deficient mice are more susceptible to developing experimental autoimmune encephalomyelitis (EAE), and treatment of Lewis rats with Zn-MT-II reduces EAE severity. We show here that, as in EAE, MT-I+II proteins were expressed in brain lesions of MS patients. Cells expressing MT-I+II were mainly astrocytes and activated monocytes/macrophages. Interestingly, the levels of MT-I+II were slightly increased in the inactive MS lesions in comparison with the active lesions, suggesting that MTs may be important in disease remission.     

Effects of low doses of ochratoxin A after intratesticular injection in the rat

Summary The toxic effect of various doses of ochratoxin A on the rat testis was investigated after a single intratesticular injection. At time of sacrifice (day 10) degenerating changes occur in the testicular tissues: seminiferous tubules dilatation, cytolysis of the seminiferous epithelium, hyperplasia of the interstitial tissue, vascular thrombosis. The relations between the blood supply disturbances and the observed lesions are discussed.     

Effects of low doses of ochratoxin A after intratesticular injection in the rat.

The toxic effect of various doses of ochratoxin A on the rat testis was investigated after a single intratesticular injection. At time of sacrifice (day 10) degenerating changes occur in the testicular tissues: seminiferous tubules dilatation, cytolysis of the seminiferous epithelium, hyperplasia of the interstitial tissue, vascular thrombosis. The relations between the blood supply disturbances and the observed lesions are discussed.     

Do prostaglandins mediate the somatostatin preventive effect on gastric lesion?

The inhibition of endogenous prostaglandin synthesis by indomethacin treatment blocks the somatostatin preventive effect on the gastric lesions induced in a stress model and has no preventive effect on an intragastric distension model.     

Pubertal changes in the medio-basal hypothalamic area after neonatal suprachiasmatic nucleus lesions in the rat

Summary In order to get more insight into the mechanism by which the onset of puberty is controlled, a developmental study on the displacement of catalase- and dopamine-containing cells in the hypothalamic region was done in rats which received a neonatal lesion of the suprachiasmatic nucleus. The displacement of cells is delayed after these lesions. However, the time lost at the beginning of the displacement is made up at the end of the migration.     

Do prostaglandins mediate the somatostatin preventive effect on gastric lesion?

Summary The inhibition of endogenous prostaglandin synthesis by indomethacin treatment blocks the somatostatin preventive effect on the gastric lesions induced in a stress model and has no preventive effect on an intragastric distension model.     

An alkaline protease in the delayed hypersensitivity skin lesions in the guinea-pigs.

An alkaline hemoglobinolytic protease was extracted from the delayed hypersensitivity skin lesions induced by bovine gamma-globulin as an antigen in the guinea-pig. The enzyme was heat-labile and inhibited by thiol-blocking reagents. The mol.wt. was more than 100,000 and optimal pH around 9.     

Pubertal changes in the medio-basal hypothalamic area after neonatal suprachiasmatic nucleus lesions in the rat

In order to get more insight into the mechanism by which the onset of puberty is controlled, a developmental study on the displacement of catalase- and dopamine-containing cells in the hypothalamic region was done in rats which received a neonatal lesion of the suprachiasmatic nucleus. The displacement of cells is delayed after these lesions. However, the time lost at the beginning of the displacement is made up at the end of the migration.     

The effects of lesions in several zones of the brain on cell multiplication in the glandular epithelium of the rat small intestine]

Radio-frequency lesions of tubero-infundibular region of the hypothalamus are followed by a significant increase of the mitotic rate in the small intestine glandular epithelium in rats. This increase does not occur when radio-frequency lesions are located in the anterior and posterior hypothalamus, in the dorsomedial thalamus and in the cerebral hemispheres.     

Similarity between the effects of suprachiasmatic nuclei lesions and of pinealectomy on gonadotropin release in ovariectomized,sulpiride-treated and melatonin-replaced rats

The aim of this study was to compare the effects of pineal indole treatments on LH and FSH release in pinealectomized and suprachiasmatic lesioned and ovariectomized rats rendered hyperprolactinemic by acute sulpiride treatment. pinealectomy or suprachiasmatic nuclei lesions in female rats both decreased plasma LH and FHS at 10, but not at 20 d after surgery, whereas the daily afternoon administration of melatonin effectively restored levels of both gonadotropins to control values. In ovariectomized rats, pinealectomy or suprachiasmatic nuclei lesions were ineffective in counteracting the high plasma levels of LH and FSH. However, sulpiride treatment in both pinealectomized and suprachiasmatic nuclei lesioned and castrated female rats significantly decreased the levels of LH and FSH, an effect which was counteracted by daily afternoon melatonin administration. Other pineal indoles tested, i.e., 5-hydroxy- and 5-methoxytryptophol, were ineffective in regulating gonadotropin levels. The results suggest that the pineal gland, through its hormone melatonin, can modulate gonadotropin secretion by acting on a dopamine mechanism independent of hypothalamic suprachiasmatic areas.     

Induction of chromosomal aberrations by the anthracycline antitumor antibiotics N,N-dimethyldaunomycin and aclacinomycin A

Summary The clastogenic effect of the anthracycline antitumor antibiotics, N,N-dimethyldaunomycin and aclacinomycin A, was studied in a murine hemopoietic cell line (Friend leukemia cells). A dose-dependent increase in chromatid lesions, i.e., achromatic lesions, chromatid breaks, chromatid deletions and triradial or quadriradial chromosomal exchange figures, was found. It appears that the clastogenicity of N,N-dimethyldaunomycin and aclacinomycin A is lower than that of the classic anthracycline, daunomycin, which is also a potent mutagen and carcinogen. The data demonstrate that the capacity of chemicals to induce point mutations and chromosomal aberrations may not necessarily be correlated: aclacinomycin A is devoid of mutagenic activity in bacterial (Salmonella typh.) and mammalian cell (HGPRT) mutagenesis assays, and is non-carcinogenic in rats. Nevertheless, it was now found to possess clastogenic activity.     

Induction of chromosomal aberrations by the anthracycline antitumor antibiotics N,N-dimethyldaunomycin and aclacinomycin A

The clastogenic effect of the anthracycline antitumor antibiotics, N,N-dimethyldaunomycin and aclarcinomycin A, was studied in a murine hemopoietic cell line (Friend leukemia cells). A dose-dependent increase in chromatid lesions, i.e., achromatic lesions, chromatid breaks, chromatid deletions and triradial or quandriradial chromosomal exchange fiqures, was found. It appears that the clastogenicity of N,N-dimethyldaunomycin and aclacinomycin A is lower than that of the classic anthracycline, daunomycin, which is also a potent mutagen and carcinogen. The data demonstrate that the capacity of chemicals to induce point mutations and chromosomal aberrations may not necessarily be correlated: aclacinomycin A is devoid of mutagenic activity in bacterial (Salmonella typh.) and mammalian cell (HGPRT) mutagenesis assays, and is non-carcinogenic in rats. Nevertheless, it was now found to possess clastogenic activity.     

Host cell reactivation capacity of different strains of E. coli B resistant or sensitive to ozone

Host cell reactivation capacity for ozonated or irradiated phage was determined for different strains of E. coli either more sensitive or resistant to ozone than the wild type strain. The results suggest that the ozr gene product could be involved in the same repair pathway for ozone-induced lesions on DNA as the polA gene. The possible involvement of a specific endonuclease for these lesions is also considered.     

Visually guided movement in the cat: difference in the effects of a bilateral lesion of the thalamic nucleus ventralis lateralis performed either before or after training]

Bilatéral lesions of the thalamic nucleus ventralis lateralis were performed in cats, either after [1] or before [2] training to reach a moving target with the forepaw. In situation [1], lesions were ineffective; in situation [2] the animal never reached normal scores. VL thus seems to be essential only in the acquisition phase of the tested visuomotor performance.     

An alkaline protease in the delayed hypersensitivity skin lesions in the guinea-pigs

Summary An alkaline hemoglobinolytic protease was extracted from the delayed hypersensitivity skin lesions induced by bovine -globulin as an antigen in the guinea-pig. The enzyme was heat-labile and inhibited by thiol-blocking reagents. The mol.wt was more than 100,000 and optimal pH around 9.We thank Prof. Hideo Hayashi and Yoshimasa Morino, Kumamoto University, for valuable discussions. This work was supported in part by grants from the Ministry of Education in Japan, the Naito Research Grant. Tokyo, and the Mitsukoshi Foundation, Tokyo.     

Lesions in suprachiasmatic nuclei simulate effects of pinealectomy on prolactin release in ovariectomized and sulpiride-treated female rats

Previous studies indicate that the pineal gland alters prolactin secretion, and it was suggested that at least part of the effect of the pineal hormone melatonin on prolactin release may be mediated by the hypothalamic structures. In this study, pinealectomy and lesions of the suprachiasmatic nuclei were found to alter serum levels of prolactin in the same direction, an effect that was counteracted by daily afternoon melatonin administration. Melatonin, but not other pineal indoles, also prevented sulpiride-induced prolactin secretion in pinealectomized or suprachiasmatic nuclei-lesioned and ovariectomized rats, which suggested that the pineal gland can modulate prolactin secretion by acting through a dopamine mechanism independent of hypothalamic suprachiasmatic structures.     

Antagonism by thyrotropin-releasing hormone (TRH) of pentobarbital-induced hypothermia in rats with brain lesions

Summary Anesthesia with a large dose of pentobarbital (55 mg/kg, i.p.) caused a sustained decrease in brain temperature (Tb), which was monitored with a probe placed in the midbrain reticular formation. The administration of TRH to the lateral ventricle antagonized this hypothermia. None of the acute surgeries examined in this paper (adrenal-demedullectomy, septal knife cuts, electrolytic lesions of the hypothalamus and midbrain knife cuts) had any essential effect on this antagonism by TRH. These results suggest that centrally-administered TRH exerts its effect on thermoregulation, at least in part, through brain structure(s) caudal to the midbrain.     

Antagonism by thyrotropin-releasing hormone (TRH) of pentobarbital-induced hypothermia in rats with brain lesions

Anesthesia with a large dose of pentobarbital (55 mg/kg, i.p.) caused a sustained decrease in brain temperature (Tb), which was monitored with a probe placed in the midbrain reticular formation. The administration of TRH to the lateral ventricle antagonized this hypothermia. None of the acute surgeries examined in this paper (adrenal-demedullectomy, septal knife cuts, electrolytic lesions of the hypothalamus and midbrain knife cuts) had any essential effect on this antagonism by TRH. These results suggest that centrally-administered TRH exerts its effect on thermoregulation, at least in part, through brain structure(s) caudal to the midbrain.