An immunohistochemical and ultrastructural comparison of the effects of 2-bromo-α-ergocryptine on intrasellar and transplanted rat pituitaries

Summary Following 2 weeks of administration of 2-bromo--ergocryptine, a marked decrease was observed in prolactin immunoreactivity of the grafted pituitaries, whereas no reduction was noted in the intrasellar pituitaries. No evidence of crinophagy was revealed by electron microscopy in prolactin cells of 2-bromo--ergocryptine-treated rats.Acknowledgments. This work was supported in part by the Medical Research Council of Canada (grant MA-6349). The excellent technical assistance of Mrs Cynthia Edwards and secretarial help of Mrs Wanda Wlodarski are gratefully acknowledged.     

Transplantation and ‘cross-transplantation’ of free muscle grafts in the rat

Zusammenfassung Nachweis, dass ein frei transplantierter Rattenmuskel besser regeneriert, wenn er 14 Tage vor der Transplantation denerviert wurde.

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Work performed during an exchange between the Czechoslovak and US Academies of Sciences and supported in part by a grant from the MDAA.     

In vitro dopaminergic neuroprotective and in vivo antiparkinsonian-like effects of Δ3,2-hydroxybakuchiol isolated from Psoralea corylifolia (L.)

Cocktail recipes containing Psoralea corylifolia seeds (PCS) are used to empirically treat Parkinson disease. A PCS isolate Δ³,2-hydroxybakuchiol (BU) can inhibit dopamine uptake in dopamine transporter (DAT) transfected Chinese hamster ovary (CHO) cells, and dopamine reuptake blockade may provide an alternative approach for ameliorating parkinsonism. Here, we assessed the potential dopaminergic neuroprotective, and antiparkinsonian-like activity of BU. BU sample size was increased by using a scale-up extraction paradigm. Pharmacologically, BU significantly protected SK-N-SH cells from 1-methyl-4-phenylpyridinium (MPP⁺) insult, produced striking inhibitory actions on dopamine/norepinephrine uptake and WIN35,428 binding in synaptosomes on in vivo administration, and significantly preventing poor performance on rotarod and dopaminergic loss in substantia nigra in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mice. BU acts by protecting dopaminergic neurons from MPP⁺ injury and preventing against MPTP-induced behavioral and histological lesions in the Parkinson’s disease (PD) model, possibly by inhibiting monoamine transporters. These findings suggest that BU could be meaningful in PD treatment. Received 14 January 2009; received after revision 22 February 2009; accepted 10 March 2009     

The effects of vitamin A nutritional status on microsomal lipid peroxidation and α-tocopherol level in rat liver

Summary In vitamin A-deficient rats, liver glutathione peroxidase activity was decreased, -tocopherol content was strongly enhanced, but microsomal liquid peroxidation remained unchanged.     

‘Holding’ and ‘endorsing’ claims in the course of scientific activities

My principal aims are to show that holding, adopting and endorsing (definitions of which I provide) are distinct cognitive attitudes that may be taken towards claims at different moments of scientific activities, and that none of them are reducible to acceptance (as defined by Jonathan Cohen); to explore in detail the differences between holding and accepting, using the controversies about GMOs to provide illustrations; and to draw some implications pertinent to democratic decision-making concerning public policies about science and technology, and to the responsibilities that scientists thereby incur.     

In vitro effects of 1,2,3,4-tetrahydro-β-naphtylamine (THNA) on succinate oxidation by rat liver homogenates

Riassunto Il consumo di ossigeno e la decolorazione del Bleu di Metilene dovuti all'ossidazione del succinato da parte di omogenati di fegato di ratto, appaiono nettamente aumentati in presenza di-tetraidronaftilammina. Viene prospettata la eventualità che tale sostanza sia in grado di esercitare un'azione attivante «diretta» sul sistema succino-deidrogenasico.     

Spectrin and calpain: a ‘target’ and a ‘sniper’ in the pathology of neuronal cells

It is well documented that activation of calpain, a calcium-sensitive cysteine protease, marks the pathology of naturally and experimentally occuring neurodegenerative conditions. Calpain-mediated proteolysis of major membrane-skeletal protein, αII-spectrin, results in the appearance of two unique and highly stable breakdown products, which is an early event in neural cell pathology. This review focuses on spectrin degradation by calpain within neurons induced by diverse conditions, emphasizing a current picture of multi-pattern neuronal death and a recent success in the development of spectrin-based biomarkers. The issue is presented in the context of the major structural and functional properties of the two proteins.Received 7 March 2005; received after revision 22 April 2005; accepted 13 May 2005     

‘Working in a new world’: Kuhn,constructivism, and mind-dependence

In The Structure of Scientific Revolutions, Kuhn famously advanced the claim that scientists work in a different world after a scientific revolution. Kuhn's view has been at the center of a philosophical literature that has tried to make sense of his bold claim, by listing Kuhn's view in good company with other seemingly constructivist proposals. The purpose of this paper is to take some steps towards clarifying what sort of constructivism (if any) is in fact at stake in Kuhn's view. To this end, I distinguish between two main (albeit not exclusive) notions of mind-dependence: a semantic notion and an ontological one. I point out that Kuhn's view should be understood as subscribing to a form of semantic mind-dependence, and conclude that semantic mind-dependence does not land us into any worrisome ontological mind-dependence, pace any constructivist reading of Kuhn.     

Some extracellular matrix elements as markers of ‘capillary tunnels’ in hypertrophied rat heart

We studied the distribution of the extracellular matrix proteins fibronectin (FN) and laminin (LM) in the hypertrophied hearts of spontaneously hypertensive rats (SHR), using an immunofluorescence method with specific antibodies. The immunohistochemical reaction was positive in the cytoplasm of some hypertrophied cardiomyocytes. The results showed that FN and LM can be used as markers for tunnels, i.e. intracardiocytic invaginations of the sarcolemma. The tunnels observed contained capillaries.     

Quantitative investigation of the P and N loss in the rat liver when using various media in the ‘freeze-substitution’ technique

Résumé Les auteurs ont examiné les possibilités de diminution du contenu en azote et phosphore et de la masse sèche au cours de la congelation-dissolution des tissus. La diminution la plus marquée a été observée après l'usage de méthanol. Tandis qu'avec l'acétone elle est insignifiante.     

Occurrence of ‘partially acid-fast’ cells in cultures of genusStaphylococcus and genusMicrococcus

Résumé Lorsqu'on applique aux populations des genresStaphylococcus etMicrococcus une coloration semblable à celle deMachiavello, on obtient des cellules différemment colorées.Ce caractère « partiellement acido-résistant » diffère du caractère tinctorial de l'acido-résistance vraie.

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These studies were done with the aid of the Medical Research Council of Canada. Grant MA-729, 1962.     

Antiproliferative effects of 4′, 5′-unsaturated adenine nucleosides on leukemia L 1210 cells in vitro

Summary Several 4, 5-unsaturated adenine nucleosides were shown to have antiproliferative activity against L 1210 leukemia cells in vitro. The active nucleosides were cytotoxic to the L 1210 cells as demonstrated by Trypan Blue uptake. The cytotoxicity was not induced by alterations in the ribonucleoside and deoxyribonucleoside triphosphate levels of the L 1210 cells.     

Enterohepatic cycling of O-(β-hydroxyethyl) rutosides and their biliary metabolites in the rat

Summary O-(-Hydroxyethyl)rutosides are shown to undergo reabsorption from the intestine following their secretion in bile.Acknowledgment. The authors wish to thank Mr P. B. Wood and Mr S. D. Godfrey for skilled technical assistance and Zyma, S. A., Nyon, Switzerland, for financial support.     

Effect of dexamethasone on Fc γ receptor expression in foetal and neonatal rat gut

Summary When injected into 12-day-old suckling rats, dexamethasone caused a precocious disappearance of Fc receptors from enterocytes of the proximal small intestine. However, dexamethasone appeared to be necessary for the maintenance or production of such receptors in foetal rat gut cultured in vitro.Supported by an award from the Science and Engineering Research Council.     

Effect of tea consumption on the levels ofα-ketoglutarate and pyruvate dehydrogenase in rat brain

Summary Administration of tea to rats fed on a normal diet results in a marked drop in brain levels of total thiamine as well as of -ketoglutarate and pyruvate dehydrogenase activities. The patterns of decrease in both enzyme activities are similar to that of total thiamine content; they drop to about 65% of the control at 14–20 weeks after continuous consumption of tea.Supported by a grant from the International Foundation for Science (IFS), Sweden.     

Pineal ‘synaptic’ ribbon numbers and melatonin synthesis of rat are resistant to guanethidine sympathectomy

Chemical sympathectomy is widely used to study the impact of the noradrenergic system on neuronal and neuroendocrine circuits. We tested the effects of intraperitoneal injections of guanethidine, an adrenergic neuron blocking agent, on selected functional parameters of the rat pineal gland which are known to be under sympathetic influence. The reliability of the method was demonstrated by the clear enophthalmus developed by experimental animals. However, neither the numbers of synaptic ribbons nor melatonin synthesis differed between treated and control rats, both parameters exhibiting the nocturnal increase seen in intact animals. These results are in striking contrast to those obtained upon chemical sympathectomy with 6-hydroxydopamine or surgical superior cervical ganglionectomy. We conclude that guanethidine is not capable of sufficiently removing noradrenergic influence from the rat pineal gland, and that this substance is thus inferior to other experimental methods of sympathectomy.     

Influence of drugs and neocortical spreading depression on hippocampal ‘arousal reaction’

Zusammenfassung In leichter Barbiturat- oder Chloralosenarkose wird die-Aktivität im Hippocampus, durch äussere oder retikulare Stimulierung induziert, von einer desynchronisierten Hippocampus-Aktivität abgelöst. Die Amplitude dieser durch Anästhetika hervorgerufenen langsamen hohen Wellen wird während der neocortikal sich ausbreitenden Depression reversibel verkleinert.     

Effect of 3,5,3′-tri-iodothyronine on cellular growth and oxygen consumption in neonatal rat brain

Summary The effect of thyroid deficiency and treatment with tri-iodothyronine (T₃) on oxygen consumption by neonatal (6-day-old and 15-day-old) rat brain was examined using glutamate, -hydroxybutyrate, succinate and ascorbate+TMPD as substrates. The respiration rates decreased significantly in 15-day-old hypothyroid pups. Treatment of normal and of hypothyroid pups with T₃ resulted in a significant increase in the respiration rate at both ages. Respiration rates with glucose as the substrate were not affected under these conditions.