Neuroma formation and abnormal afferent nerve discharges after partial beak amputation (beak trimming) in poultry

Following partial amputation of the beak recordings were taken of the electrical activity from single afferent fibers of the intramandibular nerve. A total of 192 single afferent fiber units were isolated of which 47 were classified as nociceptors, with an abnormal pattern of discharge, and 89 were abnormal spontaneously active units. Following amputation neuromas were developing by 15 days after surgery and they were well formed by 20 to 30 days. The presence of neuromas together with abnormal spontaneous activity originating from them raise serious welfare questions concerning beak trimming.     

The regeneration of newt limbs deformed in nature

Summary The regeneration of abnormal limbs from a wild newt population was examined. The abnormalities were: mirror symmetrical reduplications of digit parts, deformed wrists, or limbs with supernumerary digits. Normal regeneration resulted after amputation of the abnormal parts, regardless of the original deformity. The results suggest that the abnormalities are probably the result of local trauma to the limbs.     

The regeneration of newt limbs deformed in nature

The regeneration of abnormal limbs from a wild newt population was examined. The abnormalities were: mirror symmetrical reduplications of digit parts, deformed wrists, or limbs with supernumerary digits. Normal regeneration resulted after amputation of the abnormal parts, regardless of the original deformity. The results suggest that the abnormalities are probably the result of local trauma to the limbs.     

Response of the ampullae of Lorenzini to static combined electric and thermal stimuli in Scyliorhinus canicula.

The effect of long-lasting electric currents on the Lorenzinian ampullae at constant temperatures between and 25 degrees C was investigated in the dogfish (Scyliorhinus canicula). Steady state neural impulse patterns in single afferent units were analyzed by plotting interval length histograms and computing mean values and standard deviations for currents between -100 and +100 nA. The mean values depended on temperature and on current strength; the relative standard deviations remained almost constant (ca. 20--30%). Negative currents, inserted at the orifice of the ampullary canal led to higher, and positive currents to lower, steady impulse rates in the whole temperature range investigated here. This static component of electrosensitivity again disappeared at higher currents (of 50 nA and more; electric overstimulation). The maximum static response was two orders of magnitude less than the maximum dynamic component of electroreception. The electrosensitivity depended on temperature: the ampullae were most sensitive to electric currents between 13 and 19 degrees C. The maximal neural activity at 19 degrees C was not shifted to higher or lower temperatures by electric stimulation. A constant equivalent of electric and thermal stimulation throughout the tested temperature and current range could not be found.     

Nachweis einer physiologischen Spontanaktivität in Einzelfasern des N. opticus der Katze

Summary Spike potentials were recorded with metal micro-electrodes from single fibers in the intracranial part of the cat's optic nerve with the retina left completely intact. All units studied as yet showed a marked spontaneous activity irrespective of differences in their response to light stimuli. The spontaneous activity in the intracranial part of the optic nerve could be suppressed reversibly by increasing the intraocular pressure up to 200 mm Hg. Thus spontaneous activity has been verified as a normal feature of the retina. A spontaneous firing rate of 22±11/s after 1 h dark adaptation was found in altogether 12 well-isolated fiber units.     

Regeneration induced in the forelimbs by treatment with vitamin A in the froglets ofRana breviceps

Summary Young froglets ofRana breviceps do not possess the power to regenerate forelimbs after amputation through metacarpals. However, 5 min immersion of limb stumps in an oily solution of 150,000 IU vitamin A palmitate immediately after amputation, and once on each of the 3 subsequent days, induced definite though hypomorphic regeneration in 100% cases.Acknowledgments. This research was supported by a grant from the Council of Scientific and Industrial Research, India.     

An efficient method for purification of cuprozinc superoxide dismutase from bovine erythrocytes

Cuprozinc superoxide dismutase (Cu,Zn-SOD) was isolated from bovine erythrocytes by pH-controlled ammonium sulfate-methanol extraction (ASME extraction). Adjustment of the pH of a suspension of the lysed red cells in the presence of ammonium sulfate (90% saturation) to pH 5.0, followed by partition with an equal amount of methanol, resulted in isolation of the enzyme with specific, activity of greater than 2000 units/mg of protein. Further purification using DEAE-cellulose column chromatography gave a highly purified Cu,Zn-SOD showing a single band on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Using this procedure about 14 mg of pure Cu,Zn-SOD with a specific activity of 4728 units/mg of protein can be recovered from one liter of bovine blood. The enzyme was characterized and the results obtained were in agreement with earlier reports. This procedure appears, therefore, to be a convenient method for isolating the enzyme.     

Paléotempératures indiquées par l'analyse isotopique de fossiles du crétacé inférieur des Hautes-Alpes (France)

Summary Paleotemperature determinations were made by the oxygen isotope method on 20 Belemnoids, 5 Aptychi and a Nautilus beak from the Lower Cretaceous of the Dévoluy area of the Hautes-Alpes (France). The data derived show a well-defined trend from higher temperatures in the Berriasian to a climatic minimum in the Barremian followed by a rise to the Albian maximum, previously observed elsewhere in Europe. The Aptychi are shown to be useful paleotemperature indicators utilizable in conjunction with Belemnoids. A Sequanian Aptychus gave a high temperature reading, indicating that the climate steadily cooled from Upper Jurassic times into the Barremian. The single Nautilus beak gave a result suggesting that this group of fossils may also prove valuable in similar studies in the future. The paleotemperature data also showed (by the stratigraphic position of the relevant Belemnoids) that the Aptian is either very attenuated or absent in the Dévoluy.     

17 Beta-estradiol-sensitivity of cultured myometrial cells

The estrogen sensitivity of cells cultured from the rat myometrium was studied by growing the cells in the absence or presence of 1 nM 17 beta-estradiol. Following a time lag of approximately 10 days, exposure to estrogen resulted in increased incorporation of radiothymidine by the cells. Estrogen treatment also decreased isoproterenol-dependent and GTP-dependent adenylate cyclase activity, but had no effect on basal activity. These cultured cells have been shown previously to have some properties of uterine smooth muscle. The effects estrogen has in vitro, therefore, may reflect important properties in vivo that account for the mechanism by which the sex steroid decreases the sensitivity of the myometrium to isoproterenol.     

Pralidoxime prevents certain teratogenic effects induced by bidrin in quail embryos]

Bidrin treatment of quail embryos results in axial anomalies as well as malformations of the beak and the limbs. Whereas the administration of pralidoxime to teratogen-treated embryos prevents the appearance of the axial anomalies, the morphogenesis of the beak and limbs remains profoundly altered.     

Discharge pattern analysis suggests existence of a low-threshold calcium channel in cold receptors

Summary The regular periodic activity patterns of mammalian cold receptors have been quantitatively studied. Analysis of the timing of either single impulses or impulse groups demonstrated that the periodic receptor process is maintained independently of impulse generation and continues to operate under conditions when afferent impulses are not initiated. These results imply that the underlying conductances must be operational at threshold potentials related to impulse generation. In addition to temperature, the periodic process is considerably sensitive to calcium, which affects mainly the probability of impulse generation during each cycle. Reduction of external calcium and application of calcium entry blockers with relative selectivity for low-threshold calcium channels are similarly effective in modulating cold receptor activity. The data imply the existence of a low-threshold calcium conductance at the sensory terminal.     

Discharge pattern analysis suggests existence of a low-threshold calcium channel in cold receptors.

The regular periodic activity patterns of mammalian cold receptors have been quantitatively studied. Analysis of the timing of either single impulses or impulse groups demonstrated that the periodic receptor process is maintained independently of impulse generation and continues to operate under conditions when afferent impulses are not initiated. These results imply that the underlying conductances must be operational at threshold potentials related to impulse generation. In addition to temperature, the periodic process is considerably sensitive to calcium, which affects mainly the probability of impulse generation during each cycle. Reduction of external calcium and application of calcium entry blockers with relative selectivity for low-threshold calcium channels are similarly effective in modulating cold receptor activity. The data imply the existence of a low-threshold calcium conductance at the sensory terminal.     

Spontaneous miniature potentials in primary afferent fibres

Summary Intracellular recording from primary afferent fibres of the isolated frog spinal cord revealed the existence of spontaneous synaptic activity, related probably to the firing of presynaptic inhibitory fibres.     

Neuronal degeneration in the striatum of the groggy rat: a new mutant with a movement disorder.

A new mutation displaying abnormal movement was obtained in the progeny of a female Wistar rat which had been given 10 mg/kg methylnitrosourea at an early stage of the gestational period. Genetic studies revealed that the character is inherited by an autosomal single recessive gene, and we designated this mutation groggy (gene symbol gr). The abnormal movement of the groggy rat was first apparent around postnatal day 15, while the histological studies revealed the appearance of numerous necrotic neurons in the striatum of the groggy rat on postnatal days 60 and 120.     

Spontaneous miniature potentials in primary afferent fibres.

Intracellular recording from primary afferent fibres of the isolated frog spinal cord revealed the existence of spontaneous synaptic activity, related probably to the firing of presynaptic inhibitory fibres.     

Pharmacologic therapeutic window of pramiracetam demonstrated in behavior, EEG, and single neuron firing rates

Following oral or intravenous administration, a representative cognition activator drug, pramiracetam sulfate, is shown to have a pharmacologic therapeutic window at three different levels of study: learned behavior, gross EEG activity of the frontal cortex and hippocampus, and firing rate of single hippocampal neurons.     

Neuropeptides in pelvic afferent pathways

Summary Neurochemical and pharmacological experiments have raised the possibility that several neuropeptides including, vasoactive intestinal polypeptide (VIP), peptide histidine isoleucine amide (PHI), substance P, calcitonin gene-related peptide (CGRP), neurokinin A, cholecystokinin (CCK) and opioid peptides may be transmitters in afferent pathways to the pelvic viscera. These substances are widely distributed in: 1) nerve fibers in the pelvic organs, 2) visceral afferent neurons in the lumbosacral dorsal root ganglia and 3) at sites of afferent termination in the spinal cord. Double, staining immunocytochemical techniques have shown that more than one peptide can be localized in individual visceral afferent neurons and that neuronal excitatory (VIP, substance P, CCK) and inhibitory peptides (leucine enkephalin) can coexist in the same afferent cell. Studies with the neurotoxin, capsaicin, indicate that peptidergic afferent pathways are, involved in the initiation of central autonomic reflexes as well as peripheral axon reflexes which modulate smooth muscle activity, facilitate transmission in automatic ganglia and trigger local inflammatory responses.     

Pharmacologic therapeutic window of pramiracetam demonstrated in behavior,EEG, and single neuron firing rates

Summary Following oral or intravenous administration, a representative cognition activator drug, pramiracetam sulfate, is shown to have a pharmacologic therapeutic window at three different levels of study: learned behavior, gross EEG activity of the frontal cortex and hippocampus, and firing rate of single hippocampal neurons.     

Neuropeptides in pelvic afferent pathways

Neurochemical and pharmacological experiments have raised the possibility that several neuropeptides including, vasoactive intestinal polypeptide (VIP), peptide histidine isoleucine amide (PHI), substance P, calcitonin gene-related peptide (CGRP), neurokinin A, cholecystokinin (CCK) and opioid peptides may be transmitters in afferent pathways to the pelvic viscera. These substances are widely distributed in: 1) nerve fibers in the pelvic organs, 2) visceral afferent neurons in the lumbosacral dorsal root ganglia and 3) at sites of afferent termination in the spinal cord. Double staining immunocytochemical techniques have shown that more than one peptide can be localized in individual visceral afferent neurons and that neuronal excitatory (VIP, substance P, CCK) and inhibitory peptides (leucine enkephalin) can coexist in the same afferent cell. Studies with the neurotoxin, capsaicin, indicate that peptidergic afferent pathways are involved in the initiation of central autonomic reflexes as well as peripheral axon reflexes which modulate smooth muscle activity, facilitate transmission in automatic ganglia and trigger local inflammatory responses.     

Unexpected features of the interaction between individual primary afferents and spinal motoneurones

Summary Simultaneous intracellular recording from spinal motoneurone and dorsal root fibres afferent to it in the isolated amphibian cord revealed a specific correlation between the slow spontaneous depolarizing activity in motoneurones and primary afferents.