[A kindling model of epilepsy induced by intraperitoneal injection of coriaria lactone in rats]

Fifty adult male Sprague-Dawley rats were divided into five groups. Intraperitoneal injections of various doses of coriaria lactone (CL, 0.75, 1.25, 1.75, and 2.0 mg/kg) and normal saline were given respectively per 2 days. The behavior of the rats was observed and the ECoG was recorded by telemetric method. The results of experiments show that a kindling model of epilepsy can be established by intraperitoneal injection of CL in rats. This chronic experimental model is of value for application because it is easily established and the rate of being kindled is relatively high, but the mortality is low, and the kindling effect can last well. The model can avert the pathological change caused by artificial injury to brain, so it is advantageous to the research on neurochemistry and ultrastructure. In our experimental condition, it is optimal to select 1.25 mg/kg or 1.75 mg/kg as the dosage of CL for establishing kindling model.

Determination of intracellular pH and PCO2 after metabolic inhibition by fluoride and nitrilotriacetic acid

Mean intracellular pH (pHi) and PCO2 (PiCO2) have been analysed based on pH and total CO2 measurements in tissue homogenates. Tissues were sampled from undisturbed worms (Sipunculus nudus), squid (Illex illecebrosus), trout (Salmo gairdneri), toads (Bufo marinus), and rats. Homogenate metabolism was inhibited by the addition of potassium fluoride and nitrilotriacetic acid (NTA). Model calculations revealed that the influence of dilution, medium buffers, and contamination by extracellular fluids was negligible. In white muscle tissue the resulting pHi values were virtually the same as found in studies using DMO (dimethyloxazolidinedione). If large fractions of mitochondria were present (e.g. in heart muscle), DMO derived pHi values were considerably higher, probably representing overestimates. Homogenate derived pHi values are concluded to represent the effective mean pHi by taking into account pH gradients, and the volumes and buffering of cellular compartments. High time resolution and small variability make this method especially useful to assess rapid changes in pHi, e.g. in exercising animals.

Acid and ion transfer across the gills of fish: mechanisms and regulation

This review examines the mechanisms and regulation of ion and acid transfers across the gills, focussing on freshwater fish. Apical ion-exchange mechanisms (i.e., [Formula: see text] and [Formula: see text] exchange) are shown to play an important though not exclusive role in acid–base transfers. Under some circumstances, for example when either [Formula: see text] or [Formula: see text] but not H+ levels in plasma are elevated, a second mechanism of acid–base transfer then becomes apparent. This mechanism is thought to involve diffusion of acid–base relevant and "strong" ions through paracellular channels. Factors that affect acid–base transfers across the gills include the external [NaCl] and the nature of the acid–base disturbance, the latter being at least as important as the magnitude of the disturbance. Catecholamines are shown to play an important role in the regulation of acid–base transfers across the gills, acting largely through activation of β-adrenergic receptors. Current evidence, nonetheless, suggests that other elements (e.g., α-receptors, adrenergic and cholinergic neurons) may also be involved.

Localization of calcitonin gene-related peptide in the small intestine of various vertebrate species

Calcitonin gene-related peptide (CGRP) was found extensively in the small intestine of both non-mammalian and mammalian vertebrates using radioimmunoassay and immunocytochemistry. By radioimmunoassay, the levels of CGRP in rats, mice, chickens, bullfrogs and rainbow trout were found to range from 91.5 to 419.1 ng/g tissue. To localize CGRP in the small intestine, we used three different tissue preparations for immunocytochemistry: whole-mount preparations, and frozen and Paraplast sections. The combination of three tissue preparations made it easier to visualize the three-dimensional structure and reduced the possibility of missing the immunoreaction. Immunoreactive cell bodies were found in the plexi in the mammalian species. Dense and regular networks of CGRP fibers were observed in the smooth muscle layers, when examined in whole-mount preparations. In non-mammalian species, however, immunoreactive cell bodies could not be detected, although immunoreactive fibers were present, forming less dense and regular networks. Our results indicate that CGRP-immunoreactive fibers are present in the smooth muscle layers of the intestine from fish to mammals, suggesting that CGRP may be involved in regulating gastrointestinal smooth muscles in vertebrates.

[Studies on the mutagenicity of amrinone and milrinone]

The mutagenicity of domestic new drugs amrinone and milrinone were studied by Ames test, micronucleus test of mouse bone marrow and chromosome aberration assay in CHO cells. The results were as follows: neither amrinone nor milrinone was mutagenic in the Ames test; in chromosome aberration assay, both gave positive results; in mouse micronucleus test, amrinone gave a positive result when mice were exposed to 0.8 LD50 dose, but milrinone gave a negative result. These results suggested that amrinone and milrinone did not induce gene mutation, but amrinone induced chromosome damage both in vitro and in vivo, while the chromosome-damaging activity of milrinone in vitro may be minimized by biodetoxication in vivo.

[Studies on the relation of alkaloids in semen Strychni and its processing]

This paper reports the determination of strychnine and brucine in different parts of Semen Strychni (the seeds of Strychnos nux-vomica and S. pierriana), and makes a comparison of the contents between the crude forms and processed products of the two seeds. Based on the results, the authors have made some discussion about the relationship between the alkaloid distribution in Semen Strychni and its processing.

Correlation between catecholamine release and degree of acidotic stress in trout

Exhaustive exercise in freshwater (FW) and seawater (SW) rainbow trout resulted in a marked and acute increase of plasma catecholamines. Immediately after exercise, epinephrine and norepinephrine concentrations in FW trout were 69 and 15 times the resting level, respectively; in SW trout, they were 46 and 11 times the resting value, respectively. Over the 1st h of recovery, the magnitude of the catecholamine surge in FW animals was about twice that of their SW counterparts. Correlated with this was an extracellular pH disturbance in FW trout, which was approximately twice as severe as in SW trout. Indeed, both the magnitudes and time courses of the plasma catecholamine responses were matched to those of the acid-base disturbances. Linear correlations were found to exist between the immediate depression of blood pH and the corresponding increases in plasma epinephrine and norepinephrine. We conclude that catecholamines are released into the plasma in proportion to the magnitude of the acid-base disturbance. The higher postexercise levels of plasma catecholamines in FW trout vs. SW appear to be a response to the greater acid-base disturbance in the FW animals.

Parameters of exponentially damped sinusoids in noise and their application to the analysis of visual evoked potentials

The backward prediction and singular value (SV) truncation methods for estimating multiple exponentially damped real sinusoids in noise have been studied. The basic theory and algorithm are outlined, and the effect on the error of computational parameters, such as the sampling window, the sampling rate, the order of the prediction-error filter (PEF) and the truncated point of SV, were studied using simulated data. If the computational parameters are carefully chosen, the estimate of frequency and damping factor of a damped sinusoid is quite accurate (within a certain range of signal to noise (S/N) ratio). We use this method to estimate the parameters of visual evoked potentials (VEP) and then reconstructed them from estimated parameters according to the resonant model. The error between original VEP and the reconstructed waveform is within 5%. This method can be used in the analysis and recognition of various systems.

Alpha-factor-directed synthesis and secretion of beta-subunit of human choriogonadotropin (beta-hCG) in yeast S. cerevisiae

A couple of shuttle vectors (pYNA and pYNB), containing a sequence coding for the leader region of the alpha-factor precursor (alpha-factor leader sequence) and the origin of 2 micron circle, were constructed. The cDNA for the beta-hCG (145aa) was fused in phase to the 3'-end of the alpha-factor leader sequence and transformed into the yeast Saccharomyces cerevisiae. The yeast cells carrying this hybrid gene synthesized and secreted a protein with the immunoactivity of beta-hCG in an amount of 45 micrograms per liter of culture. The preliminary characterization of this protein is also reported in this paper.

Acid-base regulation following acute acidosis in seawater-adapted rainbow trout, Salmo gairdneri: a possible role for catecholamines

A fall in blood pH was induced by intra-arterial infusion of HCl in seawater-adapted rainbow trout (Salmo gairdneri). The acute acidosis resulting from HCl infusion caused a short-lived decrease in plasma bicarbonate concentration ([HCO3-]) and an increase in arterial CO2 tension (PaCO2). Erythrocyte pH and bicarbonate concentrations were not significantly altered by the infusion of acid. Injection of acid did, however, stimulate a branchial net H+ efflux which could be primarily accounted for by a net uptake of bicarbonate equivalent ions from the environmental water. Acid infusion of animals pre-treated with the beta-adrenergic blocking agent, propranolol, induced a similar pattern of change in plasma acid-base status. However, the recovery of plasma pH and restoration of plasma [HCO3-] were slower than in animals infused with acid alone. Red cell pH fell significantly in the face of plasma acidosis in the beta-blocked animals. Erythrocyte [HCO3-] showed a similar pattern of change to that of erythrocyte pH. Branchial net H+ efflux increased to a lesser extent following acid infusion in animals treated with propranolol. We conclude that catecholamines released into the bloodstream during periods of acute acidosis may play an important role in facilitating branchial H+ efflux in seawater-adapted rainbow trout.

Venous bridge used in free flap transfer for the lower leg in the presence of venous hypertension: a case report

Reconstruction with free flaps for the lower leg in the presence of venous thrombosis or venous hypertension has a high risk of failure. We describe the use of the contralateral leg for venous drainage through a pedicled skin bridge containing a tributary of the long saphenous vein. The recipient artery was a main artery of the ipsilateral leg. Two weeks later, once there was a well-established venous communication between flap and recipient site, the venous bridge was divided. Because the arterial inflow to the flap was not interrupted by the division of the skin bridge, the flap has good viability and good resistance to infection or ulceration 3 years later.