Oenocyte and prothoracic gland activity inManduca sexta under varying photoperiod and light conditions

Summary Manduca sexta larvae were subjected to diapause-inducing and diapause-preventing photoperiods, using two types of fluorescents (Indorsun and Blacklight-blue). The oenocytes, prothoracic glands (PTG) and ecdysone levels were examined in 3-day-old 5th instar larvae, 2-day-old and 10-day-old pupae. Our results indicate that oenocytes and PTG cells tend to be more active under long photoperiods while oenocytes only are active under short photoperiods in pupae in diapause. UV light has a definite effect on oenocytes while PTG cells seem to be unaffected. Ecdysone and ecdysterone levels vary with PTG and oenocyte activity at the pupal stage. The significance of these findings is discussed.This work was supported by a research associateship to L.M. by the People's Republic of China and a grant from NSERC to B.J.R.P.     

Regional vascular reactivity in rats with Guérin carcinoma (GC)

Summary Increased sensitivity to phenylephrin and a decreased one to isoproterenol has been found in regional vascular beds of GC implanted rats. Circulatory sympathetic reflex adaptation, alfa- and beta-adrenergic stimulation or blockade provoked a uniform response pattern: i.e. increase in vascular resistance of GC.     

Regional vascular reactivity in rats with Guérin carcinoma (GC).

Increased sensitivity to phenylephrin and a decreased one to isoproterenol has been found in regional vascular beds of GC implanted rats. Circulatory sympathetic reflex adaptation, alfa- and beta-adrenergic stimulation or blockade provoked a uniform response pattern: i.e. increase in vascular resistance of GC.     

Role played in man by myelinated fibers of different diameters for the evocation of a nociceptive flex reflex and the accompanying pain sensation]

Using simultaneous recordings we have made in Man a comparative study of: the sural nerve afferent volley, the nociceptive flexor reflex of a muscle of the lower limb and the associated painful sensation. Two types of stimulations were used, a single short duration electric stimulus, and a train of electric shocks (100/sec). With a single stimulus, the nociceptive flexor reflex and the painful sensation develop only when A delta fibers are recruited. On the other hand, when the stimulations are given by trains the nociceptive flexor reflex and the painful sensation can develop with a stimulus sub-liminar to the threshold of A delta fibers, when A alpha fibers are recruited. When the stimulus activate both A alpha and A delta fibers, the flexion reflex and the pain disappear when a selective blockade of the A delta group is exerted by means of Lidocain.     

Nagel on reduction

This paper attempts a critical reappraisal of Nagel's (1961, 1970) model of reduction taking into account both traditional criticisms and recent defenses. This model treats reduction as a type of explanation in which a reduced theory is explained by a reducing theory after their relevant representational items have been suitably connected. In accordance with the deductive-nomological model, the explanation is supposed to consist of a logical deduction. Nagel was a pluralist about both the logical form of the connections between the reduced and reducing theories (which could be conditionals or biconditionals) and their epistemological status (as analytic connections, conventions, or synthetic claims). This paper defends Nagel's pluralism on both counts and, in the process, argues that the multiple realizability objection to reductionism is misplaced. It also argues that the Nagel model correctly characterizes reduction as a type of explanation. However, it notes that logical deduction must be replaced by a broader class of inferential techniques that allow for different types of approximation. Whereas Nagel (1970), in contrast to his earlier position (1961), recognized the relevance of approximation, he did not realize its full import for the model. Throughout the paper two case studies are used to illustrate the arguments: the putative reduction of classical thermodynamics to the kinetic theory of matter and that of classical genetics to molecular biology.     

Evolution in time of transmitter release at frog neuromuscular junction]

It has previously been shown that the unitary quantal end-plate potentials observed at synapses blocked by low Ca++ high Mg++ ringer, belong to distinct clusters according to their amplitude, time to peak and latency characteristics. These clusters correspond probably to distinct releasing units dispersed along the presynaptic terminal branches. The distribution versus time of the occurence of unitary potentials belonging to one latency cluster has been studied over long lasting evoked nerve activity (stimulation frequencies: 1 to 10 Hz). It was observed that transmitter release at one releasing site is statistically periodic with emitting periods separated by rest periods. At a given end-plate the period of emitting activity seems to be independent from one emitting site to another.     

Piroxicam-induced analgesia: Evidence for a central component which is not opioid mediated

Piroxicam is a nonsteroidal anti-inflammatory drug with a potent analgesic effect. In order to establish whether the analgesic action of Piroxicam has a central component, we studied the effect of the drug on the nociceptive orbicularis oculi reflexes evoked by electrical stimulation of the cornea and supraorbital nerve in healthy subjects. Piroxicam significantly suppressed the corneal reflex and R3 component of the blink reflex by 28% (p<0.05) and 50% (p<0.01), respectively. This effect was not reversed by the i.v. injection of naloxone. Beta-endorphin levels did not change. Piroxicam administration induces distinct inhibitory changes in nociceptive reflexes, which suggests that the analgesic action of the drug has a central component. The ineffectiveness of naloxone, and the lack of beta-endorphin changes, indicate that this central action is independent of the opioid system; other pain regulatory systems are probably involved.     

Piroxicam-induced analgesia: evidence for a central component which is not opioid mediated.

Piroxicam is a nonsteroidal anti-inflammatory drug with a potent analgesic effect. In order to establish whether the analgesic action of Piroxicam has a central component, we studied the effect of the drug on the nociceptive orbicularis oculi reflexes evoked by electrical stimulation of the cornea and supraorbital nerve in healthy subjects. Piroxicam significantly suppressed the corneal reflex and R3 component of the blink reflex by 28% (p < 0.05) and 50% (p < 0.01), respectively. This effect was not reversed by the i.v. injection of naloxone. Beta-endorphin levels did not change. Piroxicam administration induces distinct inhibitory changes in nociceptive reflexes, which suggests that the analgesic action of the drug has a central component. The ineffectiveness of naloxone, and the lack of beta-endorphin changes, indicate that this central action is independent of the opioid system; other pain regulatory systems are probably involved.     

Cardiomyocyte growth and sarcomerogenesis at the intercalated disc

Cardiomyocytes grow during heart maturation or disease-related cardiac remodeling. We present evidence that the intercalated disc (ID) is integral to both longitudinal and lateral growth: increases in width are accommodated by lateral extension of the plicate tread regions and increases in length by sarcomere insertion within the ID. At the margin between myofibril and the folded membrane of the ID lies a transitional junction through which the thin filaments from the last sarcomere run to the ID membrane and it has been suggested that this junction acts as a proto Z-disc for sarcomere addition. In support of this hypothesis, we have investigated the ultrastructure of the ID in mouse hearts from control and dilated cardiomyopathy (DCM) models, the MLP-null and a cardiac-specific β-catenin mutant, cΔex3, as well as in human left ventricle from normal and DCM samples. We find that the ID amplitude can vary tenfold from 0.2 μm up to a maximum of ~2 μm allowing gradual expansion during heart growth. At the greatest amplitude, equivalent to a sarcomere length, A-bands and thick filaments are found within the ID membrane loops together with a Z-disc, which develops at the transitional junction position. Here, also, the tops of the membrane folds, which are rich in αII spectrin, become enlarged and associated with junctional sarcoplasmic reticulum. Systematically larger ID amplitudes are found in DCM samples. Other morphological differences between mouse DCM and normal hearts suggest that sarcomere inclusion is compromised in the diseased hearts.     

Non-A non-B hepatitis virus: demonstration of a double antigenic and structural kinship with hepatitis B virus

Major antigenic identity has been demonstrated by immunodiffusion between the Ag described by Shirachi and confirmed by us (NANB/e) in the serum on non A non B hepatitis and the HBe/3 specificity of hepatitis B virus (HBV). A second Ag (NANB/c) linked to the core of a new virion morphologically similar to HBV and also associated with ADN polymerase activity as recently described, has been identified and purified from an infected liver. This NANB/c Ag also cross reacts with HBc Ag. These results confirm that HBV and the NANB virus defined here belong to the same new class of DNA viruses.     

Existence of different populations of unitary evoked postsynaptic potentials at the frog neuromuscular junction]

The postsynaptic response to monoquantic evoked transmitter release (mean quantal content about 0.3) has been studied at temperatures from 10 to 23 degrees C. The delay between nerve stimulation (1 to 10 Hz) and the unitary postsynaptic potentials fluctuates by steps. The existence of preferential delay sites can always be detected (mean number 13.5 +/- 3.1). Identical delay unitary postsynaptic potentials often shows identical amplitude and identical time to peak. These results suggest that few emitting sites are preferentially activated along the nerve terminal at low level release during long lasting stimulation. The "single process" assumption used in statistical studies of transmitter release is probably oversimplified.     

Different biological behavior of AKR lymphoma cells from primary and metastatic tumors

AKR lymphoma cells derived from primary s.c. tumors (PT) and cells from their metastases (MT) were inoculated into recipient mice in order to compare their malignant behavior. A higher malignant potential of MT compared to PT cells was found. The results support the hypothesis that metastasis is a process of selection of cells possessing a potential to metastasize, which preexist in the primary tumor. In the model used, both the selection of 'variants' of malignancy and the assay of malignancy were as close as possible to natural tumor progression.     

Ricerche fisiologiche sulla distribuzione periferica del nervo depressore aortico destro nel cane

Summary The periferal distribution of the right aortic nerve has been studied in physiological experiments on the dog. It has been found that after section of both Hering's nerves and left vago-depressor trunk and after denervation of the baroceptor area ofMuratori-Nonidez lying at the root of the right subclavian artery, the electrical stimulation of one splancnic nerve or the intravenous injection of adrenaline still produces a reflex bradycardia; moreover the cooling of the vagus nerve still results in a rise of the blood pressure. It is inferred that a group of baroceptor fibres of the right aortic nerve originate from areas situated in the aortic region.     

Different action of alpha-methyl-DOPA on sleep and labyrinth learning in 2 inbred strains of mice]

In two inbred mice strains C 57 BR and C 57 BL/6 presenting the same type of sleep, but a different capacity of learning, Alpha-Methyl-Dopa (100 mg/kg) injected after every session, suppresses paradoxical sleep completely for 9 to 11 h. Maze-learning performance is retarded in C 57 BR mice, but facilitated in C 57 BL/6.     

Annual modulation experiments,galactic models and WIMPs

Our task in the paper is to examine some recent experiments (in the period 1996–2002) bearing on the issue of whether there is dark matter in the universe in the form of neutralino WIMPs (weakly interacting massive particles). Our main focus is an experiment performed by the DAMA group that claims to have found an ‘annual modulation signature’ for the WIMP. DAMA's result has been hotly contested by two other groups, EDELWEISS and CDMS, and we study the details of the experiments performed by all three groups. Our goal is to investigate the philosophic and sociological implications of this controversy. Particularly, using an innovative theoretical strategy suggested by (Copi, C. and L. M. Krauss (2003). Comparing interaction rate detectors for weakly interacting massive particles with annual modulation detectors. Physical Review D, 67, 103 507), we suggest a new way of resolving discordant experimental data (extending a previous analysis by (Franklin, A. (2002). Selectivity and discord. Pittsburgh: University of Pittsburgh Press). In addition, we are in a position to contribute substantively to the debate between realists and constructive empiricists. Finally, from a sociological standpoint, we remark that DAMA's work has been valuable in mobilizing other research teams and providing them with a critical focus.     

The instability of dietary iodine supply over time in an affluent society

In the Bernese region, where goiter was formerly endemic, alimentary salt has been supplemented by increasing amounts of potassium iodide (KI): 5, 10, 20 mg KI/kg in 1922, 1965 and 1980 respectively. Ioduria rose from <30 g I/g creatinine in 1920 to >100g I/g creatinine in the 1980s. In 1992 ioduria was estimated in 55 healthy volunteers (group A and individual B) and 234 thyroid carcinoma patients after thyroidectomy: hypothyroid patients with (C) and without thyroid remnants (D) and euthyroid patients on T4^** substitution (E). The arithmetic mean iodine excretion of the healthy volunteers in group A and individual B was found to be 87±40 g I/g creatinine. This is insufficient according to the recommendations of the WHO. In all groups, the iodine excretion reached the recommended level only in some members: 24% (A, B), 19% (C), 38% (D) and 81% (E).It was thought in the 1980s that in a formerly iodine-deficient society, iodinated salt would continue to provide an adequate supply of iodine. However, iodine intake in this affluent society has proved to be unstable. This can be attributed to modifications of eating habits, which include a reduction of total salt consumption, combined with a growing consumption of manufactured food of cosmopolitan origin, prepared using salt containing little or no iodine.     

Regulatory peptides in the respiratory system

Many regulatory peptides have been described in the respiratory tract of animals and humans. Some peptides (bombesin, calcitonin, calcitonin gene-related peptide) are localised to neuroendocrine cells and may have a trophic or transmitter role. Others are localised to motor nerves. Vasoactive intestinal peptide and peptide histidine isoleucine are candidates for neurotransmitters of non-adrenergic inhibitory fibres and may be cotransmitters in cholinergic nerves. These peptides may regulate airway smooth muscle tone, bronchial blood flow and airway secretions. Sensory neuropeptides (substance P, neurokinin A and B, calcitonin gene-related peptide) may contract airway smooth muscle, stimulate mucus secretion and regulate bronchial blood flow and microvascular permeability. If released by an axon reflex mechanism these peptides may be involved in the pathogenesis of asthma. Other peptides, such as galanin and neuropeptide Y, are also present but their function is not yet known.     

Regulatory peptides in the respiratory system

Summary Many regulatory peptides have been described in the respiratory tract of animals and humans. Some peptides (bombesin, calcitonin, calcitonin gene-related peptide) are localised to neuroendocrine cells and may have a trophic or transmitter role. Others are localised to motor nerves. Vasoactive intestinal peptide and peptide histidine isoleucine are candidates for neurotransmitters of non-adrenergic inhibitory fibres and may be cotransmitters in cholinergic nerves. These peptides may regulate airway smooth muscle tone, bronchial blood flow and airway secretions. Sensory neuropeptides (substance P, neurokinin A and B, calcitonin gene-related peptide) may contract airway smooth muscle, stimulate mucus secretion and regulate bronchial blood flow and microvascular permeability. If released by an axon reflex mechanism these peptides may be involved in the pathogenesis of asthma. Other peptides, such as galanin and neuropeptide Y, are also present but their function is not yet known.