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Y Xie

Publications and source records attributed to Y Xie.

At least 415 records · Page 23Linked to original sources
PubMed1992

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.

Base Sequence↗
PubMed1992

[Construction and identification of vectors containing maize plasmid-like DNA S1 and reporter genes].

The reporter Gene GUS with CaMV 35S promoter was inserted into plasmid pBS[1] in reversal direction of integration, and two kinds of recombinant plasmids were obtained. These results were verified by restriction endonuclease analysis and southern hybridization. A piece of 10.8kb fragment containing NPT II reporter gene from digested pBI121.1 by BamHI and EcoRI was ligated together with 3.9 kb fragment of plasmid-like DNA S1. Then generate a recombinant plasmid pBIS5 was generated. These three vectors can be used to transform maize protoplasts. High frequency of transformation may be expected due to homology between plasmid-like DNA S1 and maize nuclear DNA.

DNA↗
PubMed1992

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.

Animals↗
PubMed1991

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.

6-Cyano-7-nitroquinoxaline-2,3-dione↗
PubMed1991

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)

Adenosine Triphosphate↗
PubMed1991

[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.

Acetylcholinesterase↗
PubMed1991

[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).

Animals↗
PubMed1991

[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.

Adult↗
PubMed1990

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.

Alcohol Dehydrogenase↗
PubMed1990

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.

Demography↗
PubMed1990

[Effect of reserpine on both CL seizures and cAMP levels in seizure mice brain].

Reserpine injection (1 mg/kg i.p.) could not only significantly reduce cAMP levels in both cerebral cortex and hippocampus in naive WC1 mice, but also potentiate the degree of seizures elicited by CL. Reserpine injection could significantly shorten CL-seizures latency and decrease its threshold, too. Reserpine pretreatment could also diminish CL seizure-induced accumulation of cAMP. These results indicated the cAMP level elevated by seizure activity was associated with monoamine neurotransmitter activity, and the seizure-induced accumulation of cAMP might take part in the process which eliminated the spread of seizure discharges and speeded up the termination of seizures.

Animals↗
PubMed1990

[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.

Animals↗
PubMed1990

[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.

Animals↗
PubMed1990

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.

Animals↗
PubMed1990

[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.

Action Potentials↗
PubMed1990

[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.

Animals↗