Control of the hypothalamus-pituitary-adrenal axis in young and older rats injected with thyroxine.

Administration of T4 on alternate weeks for 30 weeks at a dosage which does not alter body weight depresses basal serum corticosterone levels in older rats (575 days), but not in young animals (260 days). Similar serum corticosterone response to HPA axis stimulation occurs regardless of age or T4 injection.     

Failure to identify 'thrombocytolysin' (a spasmogenic factor released from platelets immunoreaction) with anaphylatoxin

Horse platelets release an unidentified smooth muscle contracting substance after lysis by antiserum and complement. Since the active factor (thrombocytolysin) does not produce tachyphylactic response of the guinea-pig ileum it seems that it is not related to anaphylatoxins.     

Failure to identify ‘thrombocytolysin’ (a spasmogenic factor released from platelets by immunoreaction) with anaphylatoxin

Summary Horse platelets release an unidentified smooth muscle contracting substance after lysis by antiserum and complement. Since the active factor (thrombocytolysin) does not produce tachyphylactic response of the guinea-pig ileum it seems that it is not related to anaphylatoxins.     

Mécanisme d'action du chloramphénicol dans l'inhibition de la production d'anticorps induite par de différents types d'antigènes

Summary Chloramphenicol (CAF) administered to rabbits during the whole period of immunization, is able to suppress almost completely the antibody response against horse serum albumin and globulins (HSA, HSG) andEscherichia coli: on the other hand, it does not inhibit antibody response to heterologous RBC. The possible mechanism of the inhibiting action of the CAF in antibody response to HSA, HSG andE. coli is discussed, and some hypotheses are put forward on the possible reasons for the different behaviour of CAF on the immune response induced by heterologous RBC.     

Effect of sodium butyrate on the interferon sensitivity of normal or cells transformed by murine sarcoma virus]

Sodium butyrate enhances the sensitivity of MSV transformed murine cells to interferon, but does not influence the response of normal cells. Sodium butyrate might act in transformed cells by restoring the different elements of the cytoskeletal system.     

Platelet aggregation following electrical stimulation

Summary It was demonstrated that the previous in vitro electrical stimulation of human and rat platelet-rich plasma does not modify the subsequent response of platelets to the aggregating activity of ADP, thrombin, thrombofax or adrenaline. This is interesting in view of the fact that the electrical stimulation can induce clot retraction.Acknowledgments. We thank Mr Renzo Ferronato for his technical assistance and Miss Maria Tommasini for her secretarial aid.     

Platelet aggregation following electrical stimulation

It was demonstrated that the previous in vitro electrical stimulation of human and rat platelet-rich plasma does not modify the subsequent response of platelets to the aggregating activity of ADP, thrombin, thrombofax or adrenaline. This is interesting in view of the fact that the electrical stimulation can induce clot retraction.     

Treatment of mice with monosodium,glutamate does not inhibit a subsequent response to gold thioglucose

Summary Neonatal mice were injected with monosodium glutamate (MSG) followed 10 days later by treatment with gold thioglucose (GTG). Weight gain, food consumption and body lipid determinations were made. Results indicated that pretreatment with MSG does not block subsequent response to GTG and the resulting changes are similar to those induced by GTG alone.     

Treatment of mice with monosodium glutamate does not inhibit a subsequent response to gold thioglucose

Neonatal mice were injected with monosodium glutamate (MSG) followed 10 days later by treatment with gold thioglucose (GTG). Weight gain, food consumption and body lipid determinations were made. Results indicated that pretreatment with MSG does not block subsequent response to GTG and the resulting changes are similar to those induced by GTG alone.     

Étude de la compétition antigénique chez des souris thymectomisées à la naissance

Summary The injection of horse red blood cells into the mouse 4 days before immunization with sheep red blood cells produces an inhibition of the primary response against sheep red blood cells. If the animal is thymectomized at birth, this antigenic competition does not occur. These findings do not permit a choice between the two hypotheses about antigenic competition.     

Effect of glucagon administration on serum calcium and inorganic phosphorus in the freshwater mud eel,Amphipnous cuchia

Summary Glucagon injection inAmphipnous cuchia evokes a decreased level of serum calcium on day 1 which progresses till day 3. This response declines after day 5. The serum inorganic phosphorus level does not show any significant change.     

Effect of testosterone on the hypothalamic-pituitary-gonadal axis of pinealectomized and pineal-intact male rats.

Previous studies indicate that steroid hormones alter pineal biochemistry, and it has been suggested that at least part of the negative feedback effect of steroid hormones on pituitary gonadotropin release may be mediated by the pineal gland. In this study, pinealectomy did not alter the inhibitory effect of testosterone on neuroendocine-gonadal activity in the male rat, suggesting that the pineal gland does not mediate the response of the rat hypothalamic-pituitary axis to testosterone.     

Les manifestations électriques consensuelles de l'activité rétinienne chez l'homme (Electrorétinographie binoculaire)

Summary Binocular Electroretinography in man shows that the elective light-stimulation of one retina produces a normal Electroretinogramm at the stimulated, ipsilateral eye, furthermore a bioelectric consensual response at the contralateral eye. This latter response consists in a positive deflection, corresponding to increased electropositivity under the corneal electrode. A close synchronism exists between the consensual response and the secondary rise (c-potential) of the ipsilateral Electroretinogramm. The consensual response does not appear to be of pupillary or oculomotor origin, but can probably be identified with thec-potential, the significance of which will have to bee reexamined, as well as the problem of the efferent innervation of the retina.     

Cellular responses to mild heat stress

Since its discovery in 1962 by Ritossa, the heat shock response has been extensively studied by a number of investigators to understand the molecular mechanism underlying the cellular response to heat stress. The most well characterized heat shock response is induction of the heat shock proteins that function as molecular chaperones and exert cell cycle regulatory and anti-apoptotic activities. While most investigators have focused their studies on the toxic effects of heat stress in organisms such as severe heat stress-induced cell cycle arrest and apoptosis, the cellular response to fever-ranged mild heat stress has been rather underestimated. However, the cellular response to mild heat stress is likely to be more important in a physiological sense than that to severe heat stress because the body temperature of homeothermic animals increases by only 1–2°C during febrile diseases. Here we provide information that mild heat stress does have some beneficial role in organisms via positively regulating cell proliferation and differentiation, and immune response in mammalian cells.Received 14 May 2004; received after revision 2 August 2004; accepted 16 August 2004     

Anomalous stability of insulin at very high pressure

Insulin is unaffected by pressures of 48,000 b in the solid state at room temperature, as elucidated both by spectroscopic measurements and bioassay. Its compression curve is reversible. The presence of water does not alter this property. Of a number of other proteins investigated insulin appears to be unique with regard to its pressure stability. The relative rigidity of the molecule combined with its small size may account for some of these properties.     

The response of Ca-mediated action potentials and contractile activity in mammalian ventricular myocardium towards alkalosis.

Alkalosis (pH 7.8) produced by reduction of CO2 concentration augmented both upstroke velocity of Ca action potentials and isometric contractile force of mammalian heart muscle. If the increase of pH to 7.8 was achieved by a raise of HCO3 concentration (with simultaneous reduction of CO2 concentration), the positive inotropic response was not accompanied by an augmented Ca current. Obviously, the well-known positive inotropic effect of alkalosis does not only depend upon the enhancement of transmembrane Ca influx during excitation, but can be mediated alone by affecting intracellular Ca movements as well.     

Synthesis of S-lactoyl-glutathione using glyoxalase I bound to sepharose 4B

Summary Glyoxalase I bound to Sepharose 4B was used for synthesis of S-lactoyl-glutathione. The bound enzyme does not lose its activity during several months storing and can be used many times for synthesis of S-lactoyl-glutathione. This reaction product can be used as a substrate for glyoxalase II without any further purification.This work was supported by VI Department Medical Sciences of the Polish Academy of Science.     

Newton’s De gravitatione: a review and reassessment

The widely accepted supposition that Newton’s De gravitatione was written in 1684/5 just before composing the Principia is examined. The basis for this determination has serious difficulties starting with the failure to examine the numerical estimates for the resistance of aether. The estimated range is not nearly nil as claimed but comparable with air at or near the earth’s surface. Moreover, the evidence provided most likely stems from experiments by Boyle, Hooke, and others in the 1660s and does not use evidence available in the late 1684. The document supports Newton’s contention that the aether medium incorporates very large voids thereby proving that body and space differ but does by no means completely reject its corporeal nature or eliminate its resistance. Newton’s use of the term inertia provides no conclusive evidence for a late date as often claimed and his definition of gravitas is difficult to reconcile with a late one.     

The role of Sonic hedgehog in neural tube patterning

In the developing neural tube of vertebrate embryos, many types of neural and nonneuronal cells differentiate in response to the secreted signalling molecule, Shh. Shh shows a spatially restricted pattern of expression in cells located at the ventral midline, yet governs the differentiation of diverse cell types throughout the ventral half of the neural tube. Here, we describe how the distinct fate assumed by cells in response to Shh is dependent upon their position with respect to both the dorso-ventral and anterior-posterior axes of the neural tube and describe the ways in which a single factor, Shh, is able to pattern the developing nervous system. We first discuss the evidence that Shh does impose ventral identity on cells in the neural tube, then focus on the role of a graded Shh signal in patterning the neural tube and finally discuss the interaction of Shh with other factors that affect its signalling outcome.