[Observation of paired-pulse depression in CA1 region of hippocampal slices from coriaria lactone-kindled rats]

Paired-pulse depression (PPD) technique was used to investigate the potency of recurrent synaptic inhibition mediated by GABA in area CA1 of 54 hippocampal slices from coriaria lactone (CL)-kindled and control rats. When paired stimuli were sent to the axon of CA1 pyramidal cell and Schaffer collaterals, the effect of population spike PPD lasted about 40-60ms; no significant change was observed on PPD potency between kindled and control groups (P = 0.06, 2-way ANOVA). The results indicate that the GABA-ergic synaptic inhibition seemed not to play a key role in the maintenance of the chemical kindling induced by CL.

Effects of oxidizing and reducing analogs of acetylcholine on neuronal nicotinic receptors

The synthesis and pharmacological characterization of dithiobisacetylcholine and dithiobis-N,N-dimethyl-4-acetylpiperazinium (two oxidizing analogs of acetylcholine), as well as those of their reduced counterparts, are described. Both the oxidizing and reducing analogs stimulate nicotinic receptors in the chick retina and block the binding of 125I-labeled neuronal bungarotoxin to retinal homogenates (IC50 values of 2 x 10(-6) to 6 x 10(-5) M). Both oxidizing compounds reverse the physiological effects of reduction by dithiothreitol on nicotinic function in intact chick retina, when applied for 2 sec (EC50 values of about 10(-5) M). This effect is selective, insofar as neither agent alters the effects of dithiothreitol treatment on receptors for N-methyl-D-aspartate. Reoxidation takes place at the disulfide located near the nicotinic receptor agonist binding site, inasmuch as reoxidation by these agents prevents affinity alkylation by bromoacetylcholine, and occupation by the competitive antagonist d-tubocurarine prevents reoxidation. Unlike thiocholine, a weak agonist with a free sulfhydryl that, paradoxically, is reported to oxidize nicotinic receptors in electroplax, the reduced forms, mercaptoacetylcholine and N,N-dimethylamino-4-mercaptoacetylpiperazinium, have no direct redox effects on retinal receptors, but they do protect the receptors against reduction by dithiothreitol.

Endothelin-1 stimulates contraction and ion transport in the rat colon: different mechanisms of action

Endothelin-like immunoreactivity has been detected in all regions of the rat gastrointestinal tract. In the present study, we studied the effect of endothelin-1 (ET-1) on muscle contraction and ion transport in the rat colon. Isometric tension was recorded in colonic muscle strips oriented along their longitudinal axis. The effect of ET-1 on ion transport was investigated by assessing changes in short-circuit current in segments of muscle-stripped rat colon in Ussing chambers. ET-1 induced concentration-dependent contraction of the colon (EC50, 3 nM). The concentration-response curve to ET-1 was not modified by the neuronal blocker tetrodotoxin (0.1 microM) or by atropine (1 microM). Pretreatment of colon muscle strips with the calcium channel blockers diltiazem (0.1 microM) or nicardipine (1 microM) had no effect on the contractile response to ET-1. Furthermore, the response was not affected by removal of extracellular calcium. In the ion transport studies, serosal addition of ET-1 produced a transient, bumetanide (chloride secretion inhibitor) -sensitive, increase in transepithelial short-circuit current. The maximal increase was 107 +/- 13 microA/sq. cm, with an EC50 of 2.5 nM. The increase in short-circuit current evoked by ET-1 was not significantly affected by 1 microM atropine, but was reduced by 50% (P less than .05) by 1 microM tetrodotoxin, or removal of extracellular calcium. We conclude that ET-1 stimulates smooth muscle directly, whereas its effect on epithelial chloride secretion is mediated in part via the enteric nerves. Moreover, the effect of ET-1 in these two systems can be differentiated on the basis of sensitivity to extracellular calcium.

Phosphorylation regulates RNA binding by the human T-cell leukemia virus Rex protein

The Rex protein of human T-cell leukemia virus types I (HTLV-I) and II (HTLV-II) regulates the expression of the viral structural genes and is critical for viral replication. Rex acts by specifically binding to RNAs containing sequences of the R region of the 5' long terminal repeat. Two forms of Rex detected in HTLV-II-infected cells, p26rex and p24rex, differ in the extent of serine phosphorylation. Two-dimensional phosphopeptide analysis indicates that p26rex is extensively phosphorylated at multiple sites. Using a sensitive immunobinding assay, we show that the phosphorylation state of Rex determines the efficiency of binding of Rex to HTLV-II target RNAs. Thus, the phosphorylation state of Rex in the infected cell may be a switch that determines whether virus exists in a latent or productive state. These studies also suggest that phosphorylation of RNA-binding regulatory proteins is a more general mechanism of gene regulation.

[Ultrastructural observation of SC1001-sodium on brain neurons kindled seizures by coriaria lactone in rabbits]

The ultrastructural changes of hippocampus and cerebral cortex neurons were derived from the rabbits kindled by coriaria lactone and from the kindled rabbits after treatment with SC1001 Na. The results of experiment showed that the hippocampus and cerebral cortex neurons in the kindled group had some degenerative changes, such as the swelling mitochondria, dilated rough endoplasmic reticulum and Golgi complexes when the injuries of neurons were not serious, but the seriously injured neurons were subjected to rupture of the cell membrane and solution of most organella, with only a small amount of degenerative organella. In the group treated with SC1001 Na, the ultrastructure of brain neurons demonstrated a tendency of recreation to normal which showed that SC1001 Na had cured many of the degenerative brain cells. This suggested that active treatment is very important for the epileptic patients.

[Correlation among electrocardiogram, important risk factors of coronary artery diseases and coronary lesion in patients with chest pain]

Clinical and angiographic data from 103 patients with chest pain were evaluated to determine their correlation with ST-T abnormality in resting electrocardiogram. Univariate analysis suggested that male sex, hypertension, old myocardial infarction, severe coronary lesion, multiple vessel lesion and left ventricular wall motion abnormality significantly increase the likelihood of ST-T abnormality. Multivariate analysis suggested that male sex, hypertension and left ventricular wall motion abnormality were significant independent predictors of abnormal ST-T. It is essential to improve the electrocardiographic accuracy of diagnosing CAD so as to help clinical doctors in preventing and treating this disease.

Zeeman laser interferometer errors for high-precision measurements

We present a theoretical analysis of the errors of a Zeeman laser interferometer due to the nonorthogonally elliptic polarizations of laser modes. The polarizations make the measured Doppler frequency-shift signal become a modulated and nonharmonic signal and make the phase shift unstable and nonrepeatable when the signal is measured by a phasemeter. If the orthogonality error between two major axes of the laser polarizations is 6 degrees , the relative errors of the phasemeter output will exceed 200% when the measured phase shift is changed from -16.2 degrees to +3.5 degrees . We also introduce a way to eliminate the errors.

Pathophysiology of elevated ascites fluid cholesterol in malignant ascites. Increased ascites to serum relation of proteins and lipoproteins in patients with peritoneal carcinomatosis as compared to patients with cirrhosis of the liver

The existence of marked elevations of ascitic fluid cholesterol has been observed in patients with peritoneal carcinomatosis compared to patients with cirrhosis and has been found useful in differential diagnosis. This finding could be caused by an enhanced movement of plasma lipoproteins into the peritoneal cavity. To test this hypothesis we determined the fasting concentrations of total, high density lipoprotein (HDL)- and low density lipoprotein (LDL)-cholesterol, apolipoprotein-A1 (apo-A1) and apolipoprotein-B (apo-B) in serum and ascites of 17 patients with cirrhosis and 16 patients with peritoneal carcinomatosis. The movement of proteins from plasma to ascites was calculated from the ascites/serum concentration ratios of six different sized proteins with a molecular mass ranging from 54 kDa to 971 kDa. Mean values (mg/dl) for total cholesterol (92.6 vs. 21.0), HDL-cholesterol (15.6 vs. 1.8), LDL-cholesterol (63.4 vs. 16.1), apo-A1 (50.2 vs. 13.6) and apo-B (41.2 vs. 12.9) in ascites were significantly higher in peritoneal carcinomatosis than in cirrhosis. These differences could only partially be explained by the higher serum concentrations of these parameters in peritoneal carcinomatosis, but were mainly due to a lower selectivity for the movement of plasma proteins and lipoproteins into ascites (mean ascites/serum (A/S) ratio: 0.30-0.77) in peritoneal carcinomatosis as compared to cirrhosis (mean ascites/serum ratio: 0.11-0.21). In both groups about 85% of the total cholesterol in serum and ascites consisted of HDL- and LDL-cholesterol. These findings support the hypothesis that elevations in ascitic cholesterol in peritoneal carcinomatosis compared to cirrhosis are mainly caused by the increased movement of plasma HDL and LDL into the peritoneal cavity.

Expression of a partial synthetic human TNF cDNA in E. coli

A recombinant human tumour necrosis factor (rhTNF) cDNA was constructed. The TNF gene was isolated from a human genomic gene library. There are four exons in the TNF gene. The fourth exon codes for 140 amino acids of the TNF matured protein which is composed of 157 amino acids. A major portion of the fourth exon was isolated and then ligated to a synthesized DNA fragment coding for the remaining amino acids. The partial synthetic hTNF (rhTNF) cDNA thus generated was subcloned into a vector and successfully expressed in E. coli. 5-1 fermentator was used to produce rhTNF. About 20 g (wet weight) of bacterial pellet per liter medium and 10(6)-10(7) units of cytotoxicity to L929 cells per milliliter medium were obtained. rhTNF was purified by HPLC and dried with a freeze dryer. rhTNF with a purity of about 95% in the form of white powder was obtained. The sequence of ten amino acids at the amino terminus of the rhTNF was determined. The result showed that it was identical with that of the natural human TNF.

Observations of synaptic efficacy and paired-pulse facilitation in area CA1 of hippocampal slices from coriaria lactone-kindled rats

The changes of population spike(PS)/population excitatory postsynaptic potential (EPSP) slope relationship and paired-pulse facilitation (PPF) were primarily investigated with extracellular recording in stratum pyramidale to stimulation of Schaffer collaterals in CA1 region of hippocampal slices from coriaria lactone (CL)-kindled and control rats. The results were as follows: (1) neither spontaneous nor evoked epileptiform bursts were found in all hippocampal slices from CL-kindled and control rats; (2) the synaptic efficacy, expressed by the ratio of PS/EPSP slope, at low stimulation intensity ranging from 10-30% of its maximum was significantly increased on CL-kindled rats (P less than 0.05); and (3) although PPF was found in all slices, the PPF strength only at stimulation intensity of 10 and 20% of maximum was augmented remarkably in CL-kindled rats (P less than 0.002 and 0.024, respectively). According to the results from our previous work, we suggested that the increment of PS/EPSP slope ratio and PPF strength at low stimulation intensity may result from the potentiation of excitatory synaptic activity or/and the change of intrinsic excitability of pyramidal neurons.

[Ca2+ channels and the abnormal electrical activity of demyelinated nerve]

Peripheral nerve demyelination was produced in adult rats by placing loosely-constrictive ligatures around the common sciatic nerve. The postoperative behavior of these rats indicated that hyperalgesia, allodynia and possible spontaneous pain were produced. In the meantime, abnormal spontaneous afferent activities (ectopic firings)originating from the demyelinated region were recorded. Evidence showed that the application of Ca2+ and Ca2+ channel blockers modulated the abnormal activity of the injured nerve. Ca2+ facilitation was dependent on its concentration (in the range of 10-20 mol/L), while 40mol/L Ca2+ always abolished firing. Verapamil, as well as La3+, applied locally or i. v. (for verapamil) not only strongly inhibited the spontaneous ectopic firings, but also blocked discharges elicited by tetraethylammonium. It is suggested that newly formed Ca2+ channels on the naked axolemma are largely responsible for the abnormal afferent activities following demyelination of the nerve.

Effect of calcium antagonists on postischemic protein biosynthesis in gerbil brain

BACKGROUND AND PURPOSE

Prolonged inhibition of protein synthesis precedes delayed neuronal death in the CA1 sector of the hippocampus after transient cerebral ischemia. Organic calcium antagonists have been recommended for alleviation of ischemic neuronal damage. The present study was undertaken to investigate whether these drugs improve the recovery of protein biosynthesis after interruption of cerebral blood flow.

METHODS

Cerebral protein synthesis was measured biochemically and autoradiographically in gerbils submitted to 5 minutes of bilateral occlusion of the common carotid arteries followed by 2 hours or 2 days of recirculation. Flunarizine (25 mg/kg) or nimodipine (1.5 mg/kg) were applied intraperitoneally shortly after ischemia.

RESULTS

Treatment with either calcium antagonist did not markedly influence postischemic recovery of protein synthesis in the resistant regions of the brain and did not prevent the persisting inhibition in the vulnerable stratum pyramidale of the CA1 sector of the hippocampus.

CONCLUSIONS

The postischemic application of the organic calcium antagonists nimodipine and flunarizine does not promote postischemic recovery of protein synthesis. The beneficial effects of these drugs must, therefore, be based on other mechanisms.

Ischemic thresholds of cerebral protein synthesis and energy state following middle cerebral artery occlusion in rat

The ischemic threshold of protein synthesis and energy state was determined 1, 6, and 12 h after middle cerebral artery (MCA) occlusion in rats. Local blood flow and amino acid incorporation were measured by double tracer autoradiography, and local ATP content by substrate-induced bioluminescence. The various images were evaluated at the striatal level in cerebral cortex by scanning with a microdensitometer with 75 microns resolution. Each 75 x 75 microns digitized image pixel was then converted into the appropriate units of either protein synthesis, ATP content, or blood flow. The ischemic threshold was defined as the flow rate at which 50% of pixels exhibited complete metabolic suppression. One hour after MCA occlusion, the threshold of protein synthesis was 55.3 +/- 12.0 ml 100 g-1 min-1 and that of energy failure was 18.5 +/- 9.8 ml 100 g-1 min-1. After 6 and 12 h of MCA occlusion, the threshold of protein synthesis did not change (52.0 +/- 9.6 and 56.0 +/- 6.5 ml 100 g-1 min-1, respectively) but the threshold of energy failure increased significantly at 12 h following MCA occlusion to 31.9 +/- 9.7 ml 100 g-1 min-1 (p less than 0.05 compared to 1 h ATP threshold value; all values are mean +/- SD). In focal cerebral ischemia, therefore, the threshold of energy failure gradually approached that of protein synthesis. Our results suggest that with increasing duration of ischemia, survival of brain tissue is determined by the high threshold of persisting inhibition of protein synthesis and not by the much lower one of acute energy failure.(ABSTRACT TRUNCATED AT 250 WORDS)

2,4,5-trihydroxyphenylalanine in solution forms a non-N-methyl-D-aspartate glutamatergic agonist and neurotoxin

We have investigated the pharmacologic and neurotoxic properties of 2,4,5-trihydroxyphenylalanine [topa; the 6-hydroxylated derivative of 3,4-dihydroxyphenylalanine (dopa)] in central neurons. Application of solutions of topa to the chicken eyecup preparation results in glutamatergic responses mediated predominantly by non-N-methyl-D-aspartate receptors. Pharmacological activity depends upon oxidation in solution to a new compound. This compound is tentatively identified as topa quinone. Solutions of topa are toxic to cortical neurons in culture, and this toxicity is blocked by the non-N-methyl-D-aspartate antagonist 6-cyano-7-nitroquinoxaline-2,3-dione. These results suggest that production or accumulation of topa or its oxidation products might be involved in excitotoxicity, especially in dopaminergic neurons and their projection targets.

[Bulbar conjunctival microcirculation in schizophrenics]

A comparative observation on bulbar conjunctival microcirculation (BCM) between 38 schizophrenics and 38 normal controls was carried out. The results showed 95% abnormal BCM in schizophrenics. And among them, the moderate and severe abnormal BCM was 74%. And in all of the 14 investigated items, the general abnormalities were 50%. But in normal controls, abnormal BCM was 27%, and just a few of them appeared the general abnormalities, and no one suggested moderate and severe abnormal BCM. As compared the results obtained in schizophrenics with those in normal controls, we found 12 investigated items such as irregularity in diameter, dilatation and tortuosity of tiny vena; irregularity in diameter, stiff of tiny arteria; small hemorrhagic spot, brown pigmentation, red blood cells collected in tiny vena and capillary, small vascular density, speed of blood flow and arterio-venous ratio were statistically significant.

[Effects of SC1001-sodium on hippocampal kindled seizures by coriaria lactone in rabbits]

Healthy rabbits weighing 1.7-2.4 kg were used. According to Sawyer's atlas the stainless steel cannula and recording electrode were implanted into the left hippocampus of each animal. The kindling experiments were started one week after the surgical operation. For kindling, all animals received injection of 2 microliters of diluted solution containing 0.55 or 0.32 microgram of coriaria lactone (CL) every second day, through the single stainless steel cannula previously implanted in the hippocampus. Hippocampal EEG of all the animals was recorded by telemetric method and the behavior of them was observed at the same time. Eighteen fully kindled rabbits were separated into three groups. The SC1001 Na group of six rabbits was treated with SC1001 Na (100 mg/kg, i.m.), the PB Na group (six rabbits) received phenobarbital Na (30 mg/kg, i.m.), and the control group of six was treated with placebo (normal saline, i.m., in the same volume as that of the SC1001 Na injection); injections were administered once a day for two courses of treatment (one course of treatment was 1 week). The results of the experiment indicated that SC1001 Na (100 mg/kg) had certain effects on hippocampal kindled seizures induced by CL, but its curative effects were not more notable than those of PB Na (30 mg/kg).

[Observation of enzyme histochemistry and ultrastructure of brain in kindling rats with epilepsy induced by intraperitoneal injection of coriaria lactone]

Kindling model of epilepsy induced by intraperitoneal injection of Coriaria lactone (CL) was used in the experiment. The dose of CL was 1.25 mg/kg. Thirty rats in various periods of kindling were killed and the materials of cerebral cortex, hippocampus and cerebellum were drawn. The enzyme activities of AchE, NADHD, CCO, LDH, SDH, AcP, ANAE and AkP of these areas were observed with enzyme histochemical techniques. In another three kindled rats, two blank control rats and two NS control rats, the ultrastructure of neurons in hippocampus were observed. The results of experiments showed an increased activity of enzymes related to saccharometabolism and energy metabolism, indicating that the metabolism of brain in rats was increased by repeated kindling seizures. The mechanism of kindling seizure induced by CL may be related to inhibitory effect of CL on AchE activity of brain. The degeneration damage of brain neurons in kindled rats may result from using CL for a long time.

Quantitative morphological study of Langerhans cells by computerized image analysis

ATPase-stained normal and topical nitrogen mustard treated Langerhans cells (LC) in guinea pig epidermis were studied quantitatively and morphologically by computerized image analysis. Significant correlation and linear regression were found between the perimeter and square root of its area for both cytoplasm and nucleus; a theoretical basis was thus given for morphological identification of LC. The directly measured and derived geometric parameters indicated not only substantial alteration of cytoplasm morphology of post-treated LC such as cytoplasmatosis and dendrites reduction but also a potential change of nuclear size and functional status. We conclude that quantitative morphological analysis is an objective, precise and practical method for LC research.

[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.

[Variation of cAMP in cerebral cortex and hippocampus in seizure mice induced by coriaria lactone]

To study the relationship between cAMP and epilepsy, we investigated the effects of coriaria lactone (CL) on the levels of cAMP in cerebral cortex and hippocampus. Fifty normal WC1 mice were divided into 5 groups. All groups were injected with CL (2.5 mg/kg, i.m.), except the control group which was injected with NS. The concentrations of cAMP were measured after the animals had been immersed in liquid nitrogen to die at different phases of seizure development induced by CL (before seizures, in mild seizures, during severe seizures, and after severe seizures). The results indicated that the levels of cAMP in both cerebral cortex and hippocampus were significantly increased (1.73-fold and 1.33-fold) in severe seizure, and they continuously increased (1.85-fold and 1.45-fold) after severe seizures. On the other hand, no changes of cAMP were observed in mild seizures and before seizures. These data suggested that accumulation of cAMP is probably the result of seizure activity rather than the cause of seizure.

[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.