[Dynamic changes in abnormal afferent activities following peripheral nerve injury]

Peripheral nerve injury by chronic compression caused a decrease in conductive velocity or a delay in the transmission of the action potential, later blocking it completely following demyelination of the damaged nerve region. Abnormal firing activities were recorded from the injured peripheral nerve fibers after the 6-7th postoperative day. There were different patterns of abnormal firing from fibers. Regular tonic ectopic firings with high frequency were always recorded from A beta fibers. A delta/C fibers, however, had burst or irregular spikes. A single antidromic shock to the damaged region sometimes induced ectopic spikes following the expected one. The demyelinated region of the damaged nerve was very sensitive to both tetraethylammonium, a K+ channel blocker, and noradrenaline. The authors suggest that new ion channels or receptors, absent in normal, form in the damaged region.

Molecular analysis of an alcohol dehydrogenase-encoding genomic clone (adh2) from rice

An alcohol dehydrogenase-encoding gene was isolated from a rice genomic library. The coding region was sequenced, and the gene was identified as adh2. The nucleotide sequence of this gene contains an open reading frame which is interrupted by nine introns. Sequences that are important for eukaryotic gene expression, e.g. the TATA box, polyadenylation signal, intron/exon junction and putative splicing branch sites, are found in the expected locations in the rice adh2. A sequence related to the hexanucleotide core of regulatory elements identified in anaerobically induced plant genes is also present in the 5' region of the rice adh2.

[Coriaria lactone-induced epileptiform activity in the hippocampal slices of rat]

Coriaria lactone (CL) is an active constituent of a medicinal herb used as psychosolytic in traditional Chinese medicine. Recently it has been found that CL appears to act as a convulsant agent. Subsequently both acute and chronic epilepsy models caused by CL have been established successfully. In order to observe further the epileptogenic effects of CL in vitro, the hippocampal slice technique was used in experiments with 36 slices. The results are as follows: Addition of CL to the perfusion bathing the slices of rat hippocampus increased evoked-response in body layer of CA1 in a dose-dependent manner, and induced epileptiform burst. CL augmented population spike of CA1 pyramidal neurons triggered by either orthodromic stimulus (through synapses) or antidromic stimulus (direct effect on the axon of CA1 pyramidal cells) without alteration of presynaptic fiber volley and field-EPSP, and there was no significant change in latency of burst. Finally GABA had a weak effect on CL-induced epileptiform activity. These observations suggest that CL probably has a direct effect on the soma of pyramidal neurons, CL-induced epileptiform burst may be a result of altering the innate capacity of burst and increasing the intrinsic excitability of pyramidal cell membranes.

What is natural fertility? The remodeling of a concept

This paper applies three log-linear models to Louis Henry's original 1961 natural fertility data in order to test various assumptions leading to ways of obtaining a standard natural fertility schedule through explicit modeling. "The models specify that births follow an independent Poisson distribution for each age interval of each population. All parameters are estimated through an iterative maximum-likelihood procedure." The author suggests that the model selected provides better estimates of the standard natural fertility function than previous models.

An alternative purging method: controlling the composition-dependent interaction in an analysis of rates

The purging method controlling for the composition-group interaction developed by Clogg and his associates has proven useful in demographic research. This article proposes an alternative method, partial CD purging, that controls the interaction between composition and the dependent variable. The purged rates from this new method are invariant to changes in the marginal distribution of composition, but those from the earlier purging method are not. Mathematical relationships between the proposed method and other techniques are also explored.

Effect of barbiturate treatment on post-ischemic protein biosynthesis in gerbil brain

The effect of barbiturate treatment on post-ischemic cerebral protein biosynthesis was studied in gerbils subjected to 5 min transient occlusion of carotid arteries followed by 2 h or 48 h recirculation. Ischemia induced a remarkable decline of amino acid incorporation into brain proteins in most forebrain structures. The initial inhibition recovered to near normal after 2 days recirculation in all regions except the vulnerable CA1 sector. Barbiturate treatment, which previously has been shown to prevent delayed neuronal death in CA1 sector, did not ameliorate the initial inhibition of protein synthesis but it significantly improved subsequent recovery, especially in the vulnerable CA1 sector of hippocampus. These observations indicate that delayed neuronal death in CA1 sector of hippocampus results from selective failure of post-ischemic recovery and not from selective ischemic injury of the protein synthesizing machinery. This explains that delayed neuronal death can be prevented by therapeutic interventions which are initiated during the post-ischemic recirculation phase.

Genome-specific repetitive sequences in the genus Oryza

Repetitive DNA sequences are useful molecular markers for studying plant genome evolution and species divergence. In this paper, we report the isolation and characterization of four genome-type specific repetitive DNA sequences in the genus Oryza. Sequences specific to the AA, CC, EE or FF genome types are described. These genome-type specific repetitive sequences will be useful in classifying unknown species of wild or domestic rice, and in studying genome evolution at the molecular level. Using an AA genome-specific repetitive DNA sequence (pOs48) as a hybridization probe, considerable differences in its copy number were found among different varieties of Asian-cultivated rice (O. sativa) and other related species within the AA genome type. Thus, the relationship among some of the members of AA genome type can be deduced based on the degree of DNA sequence similarity of this repetitive sequence.

Elliptical polarization and nonorthogonality of stabilized Zeeman laser output

This paper gives both theoretical and experimental proof of elliptical polarization and nonorthogonality of Zeeman laser output. It verifies that the polarized modes of the output have 4-7 degrees orthogonal error which is induced by anisotropy in the laser cavity. A new formula for calculation of this orthogonal error has been derived which also provides a way to measure the anisotropy of the laser cavity. We also discuss the influence of nonorthogonality on the spectrum of the laser.

Ischemic threshold of brain protein synthesis after unilateral carotid artery occlusion in gerbils

The threshold of the relation between regional cerebral blood flow and regional cerebral protein synthesis was investigated in gerbils submitted to a 1-hour occlusion of the left common carotid artery. Blood flow was measured with [131I]iodoantipyrine and protein synthesis with [14C]leucine using double-tracer autoradiography and trichloroacetic acid wash-incubation for removal of nonincorporated tracer radioactivity. Specific activity of blood and brain leucine and [14C]leucine incorporation into brain proteins was also measured by conventional high-performance liquid chromatography to validate the autoradiographic approach. In control gerbils, gray matter blood flow ranged between 180 and 220 ml/100 g/min and fractional amino acid incorporation was approximately 80%. Unilateral carotid artery occlusion resulted in graded ischemia with blood flow between 10 and 100 ml/100 g/min. Regional cerebral protein synthesis gradually declined at blood flows of less than 100 ml/100 g/min and approached 0 at a blood flow of 40 ml/100 g/min. This threshold for complete suppression of protein synthesis is much higher than that for maintenance of tissue energy state and suggests that the size of an infarct after focal ischemia is determined by the suppression of protein synthesis rather than by the breakdown of energy metabolism.

Effect of autologous clot embolism on regional protein biosynthesis of monkey brain

Focal cerebral ischemia was produced in monkeys by injection of autologous clots into the left internal carotid artery. Regional protein synthesis was studied 2 hours after embolism by autoradiographic and biochemical evaluation of [3H]phenylalanine incorporation into brain proteins, and the results were correlated with electrophysiologic (electroencephalogram, evoked potentials) and light microscopic observations. Ischemic territories were clearly identified on autoradiograms as sharply demarcated areas with reduced radioactivity. The localization of regions with reduced protein biosynthesis correlated with the early postembolic suppression of evoked potentials but not with the (improved) functional state and the morphologic alterations at the end of the experiment. Suppression of amino acid incorporation, in consequence, is a long-lasting event that allows documentation of the initial embolic impact for at least 2 hours irrespective of the subsequent recovery process.

Presence of the atrial natriuretic factor (ANF) in human ascitic fluid

Presence of atrial natriuretic factor (ANF)-like material was demonstrated by radioimmunoassay in ascitic fluid of 14 patients with cirrhosis of the liver. Immunoreactive ANF concentrations (M +/- SEM) were 2.4 +/- 0.5 fmol/ml in ascites, significantly lower (p less than 0.001) than the corresponding plasma concentrations of 15.5 +/- 2.6 fmol/ml. High performance gel permeation chromatography and reverse phase high performance chromatography of the ascitic ANF immunoreactivity showed correspondence to the alpha human ANF (99-126). ANF levels in ascites were significantly (p less than 0.01) correlated to levels in plasma (r = 0.66).

Resistance to hypoglycemia of cerebellar transplants in the rat forebrain

Prolonged insulin-induced hypoglycemia causes widespread loss of neurons and permanent brain damage with irreversible coma. Although the deprivation of carbohydrate stores affects all brain regions, the breakdown of energy metabolism and cessation of protein synthesis occur predominantly in the cerebral cortex, caudoputamen and hippocampus. The cerebellum, brain stem and hypothalamus are largely resistant. Following transplantation of the cerebellar anlage of rat fetuses (day 15 of gestation) into the caudoputamen of adult rats, the grafts were allowed to differentiate for a period of 8 weeks. The host animals were then subjected to 30 min of severe hypoglycemia with isoelectric EEG ('coma'). In contrast to the surrounding vulnerable brain structures, protein synthesis was fully preserved within the cerebellar transplant. Grafting of fetal forebrain cortex to the same location did not result in escape from hypoglycemic cell injury. This indicates that resistance to hypoglycemia is part of the programmed differentiation of the cerebellum and develops irrespective of its location and functional integration within the nervous system.

Persistent inhibition of protein synthesis precedes delayed neuronal death in postischemic gerbil hippocampus

Regional cerebral protein synthesis was investigated in the Mongolian gerbil during recovery from forebrain ischemia produced by bilateral common carotid artery occlusion for 5 min. At various recirculation periods up to 72 h animals received a single dose of L-(3,5-3H)tyrosine and were killed 30 min later. Brains were processed for autoradiography using the stripping film technique. During the initial 30 min of recirculation autoradiographs revealed an almost complete inhibition of protein synthesis in all forebrain structures with the exception of the medio-dorsal thalamic nuclei. Between 30 min and 12 h of recirculation amino acid incorporation was completely restored in neurons of the cerebral cortex, basal ganglia, hippocampal CA3 and CA4 zones and the dentate gyrus. In CA1, early (90-min postischemia) and progressive recovery of a few irregularly dispersed neurons was observed, but the vast majority of pyramidal cells never regained their normal biosynthetic activity. Between 3 and 6 h of recirculation CA1 neurons showed faint labeling, followed by a secondary deterioration resulting in complete lack of incorporation within 12 h after restoration of blood flow. Autoradiographs at all subsequent time points exhibited persistent inhibition of protein synthesis in CA1 until neuronal necrosis occurred 2-3 days later. Thus, in contrast to ischemia-resistant cell populations with rapid progressive and complete restoration of protein synthesis, hippocampal neurons undergoing delayed necrosis are characterized by an early incomplete recovery immediately followed by a secondary persistent inhibition.

Regionally selective inhibition of cerebral protein synthesis in the rat during hypoglycemia and recovery

Regional cerebral protein synthesis was investigated in anesthetized, mechanically ventilated rats during progressive insulin-induced hypoglycemia and the recovery period following glucose infusion. Polysome profiles from precomatose animals with slow wave/polyspike EEG revealed a slight reduction of polyribosomes and a concurrent increase in monoribosomes, but autoradiographs showed a pattern of L-[3-3H]tyrosine incorporation indistinguishable from that of control rats. During the initial 30 min of insulin-induced isoelectric EEG ("coma"), autoradiographs showed a selective inhibition of protein synthesis in neurons and glial cells of the hippocampus and cerebral cortex, i.e., regions with high susceptibility for the development of hypoglycemic brain damage. Basal ganglia were less affected and areas with low vulnerability (hypothalamus, brainstem, and cerebellum) exhibited a normal pattern of amino acid incorporation. Using a flooding dose of L-[1-14C]valine (7.5 mmol/kg; 15 microCi/mmol), the rate of incorporation in cerebral cortex and cerebellum was found to be reduced to 2% and 80% of control values, respectively. Inhibition of protein synthesis was paralleled by a breakdown of polyribosomes and a concomitant increase in ribosomal subunits, indicating a block in peptide chain initiation. After 90 min of isoelectric EEG all brain structures with the exception of hypothalamus and area postrema showed an almost complete lack of amino acid incorporation. Glucose infusion after a 30-min period of hypoglycemic coma led to a partial restoration of cortical and hippocampal protein synthesis. Within 70-90 min of recovery, L-[1-14C]valine incorporation into neocortical and cerebellar proteins amounted to 47% and 125% of fasted controls.(ABSTRACT TRUNCATED AT 250 WORDS)

Regional impairment of protein synthesis in the rat brain during bicuculline-induced seizures

Protein synthesis was investigated in rats subjected to 30 min of bicuculline-induced seizures using biochemical and autoradiographic techniques. Incorporation studies were performed on freely convulsive animals following systemic administration of either a tracer dose of L-[1-14C]tyrosine or a flooding dose (7.5 mmol/kg) of L-[1-14C]valine. Using a tracer dose, amino acid incorporation was only moderately reduced (forebrain) or slightly enhanced (cerebellum/brainstem and spinal cord) but the specific radioactivity of [14C]tyrosine in the acid-soluble pool was increased 3- to 5-fold in experimental animals. After a flooding dose of [14C]valine the specific activity of the precursor amino acid was similar in control and convulsed animals. Under these conditions incorporation rates in forebrain and cerebellum/brainstem were reduced to 54 and 75%, respectively. Reduction of amino acid incorporation was even more pronounced in extraneural tissues, e.g. liver (6%), intestine (14%) and kidney (15%). Inhibition of protein synthesis in forebrain and cerebellum/brainstem was paralleled by a similar extent of polyribosome disaggregation in these regions (53 adn 78% of controls). In anaesthetized, mechanically ventilated rats, 30 min of seizure activity reduced forebrain polyribosomes to a similar extent (57%). Extraneural (hepatic) protein synthesis was also affected in physiologically controlled rats, but cerebellar polysomes were completely preserved. Autoradiographic studies using 3H-labelled amino acids were carried out to identify nerve cell populations most heavily affected. In freely convulsive rats both tracer dose and pool overloading revealed a similar regional pattern with preferential inhibition of amino acid incorporation in forebrain cortex, thalamus and the pyramidal cell layer of the hippocampus. These sites were also affected in the physiologically controlled animal, but the focal distribution of hippocampal and thalamic neurones with reduced protein synthesis differed from that in freely convulsive rats.