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J Xu

Publications and source records attributed to J Xu.

At least 1,207 records · Page 67Linked to original sources
PubMed1992

Widespread differentiation stage-specific expression of the gene encoding phosphoprotein p19 (metablastin) in mammalian cells.

p19 is a highly conserved 19 kD cytosolic protein that undergoes phosphorylation in response to diverse extracellular factors in mammalian cells. Its expression is abundant in brain and testis and is developmentally regulated. To gain insights regarding its function, we analyzed the expression of p19 mRNA in a variety of cell types during induction of differentiation. Murine erythroleukemia cells showed a moderate increase followed by a marked decrease in the abundance of p19 mRNA during induction of differentiation. In murine C2 myoblasts and primary fetal rat osteoblasts, p19 mRNA was abundant in replicating cells and decreased to undetectable levels during differentiation. In resting human peripheral blood lymphocytes, p19 mRNA was virtually undetectable but was strongly induced during blast transformation of both B and T cells. In rat liver, p19 mRNA was abundant on embryonic day 17 and decreased during early postnatal development. Upon fractionation of adult rat liver cells by centrifugal elutriation, p19 mRNA was not detected in hepatocytes while a low level was observed in a fraction enriched in non-parenchymal epithelial cells. CCl4-induced liver regeneration resulted in induction of p19 mRNA in hepatocytes. Primary cultures of embryonic and neonatal rat brain were analyzed by indirect immunofluorescence using co-staining with stage-specific markers. p19 expression was restricted to immature neurons and oligodendrocyte precursors. In contrast to the other cell types examined, the neuronal and glial precursors that express p19 were shown, using BrdU labeling, to be postmitotic both in primary culture and in vivo. The data demonstrate widespread, stage-specific expression of p19 and suggest that the protein exerts a general, lineage-independent function during induction of differentiation of mammalian cells. In view of the available evidence on the stimulation of serine phosphorylation of p19 by several growth factors, our working hypothesis is that phosphorylation of p19 may be involved in the mechanism by which growth factors control cell differentiation.

Animals↗
PubMed1992

Receptor-linked hydrolysis of phosphoinositides and production of prostacyclin in cerebral endothelial cells.

The receptor agonist-mediated hydrolysis of phosphoinositides and production of prostacyclin were studied in murine cerebral endothelial cells (MCEC). Of 11 neurotransmitters and neuromodulators examined, carbachol, noradrenaline (NE), bradykinin, and thrombin significantly increased 3H-inositol phosphate accumulation in the presence of LiCl (20 mM). The maximal stimulation of [3H]inositol monophosphate ([3H]IP1) reached approximately 11, 11, seven, and four times the basal levels for carbachol, NE, bradykinin, and thrombin, respectively. The EC50 values of IP1 accumulation for carbachol and NE were 34 and 0.16 microM, respectively. The muscarinic antagonists, atropine and pirenzepine, blocked the carbachol-induced IP1 accumulation with Ki values of 0.3 and 30 nM, respectively. The adrenergic antagonist, prazosin, blocked NE-induced IP1 accumulation with a Ki of 0.1 nM. The calcium ionophore A23187, histamine, glutamate, vasopressin, serotonin, platelet activating factor, and substance P did not stimulate IP1 accumulation. A23187, bradykinin, and thrombin stimulated prostacyclin release to approximately four, four, and two times the basal levels, respectively, whereas carbachol and NE had little effect upon prostacyclin release. These results suggest that the activation of phospholipase C and of phospholipase A2 in MCEC are regulated separately.

Animals↗
PubMed1992

Stimulation of fetal rat lung cell proliferation in vitro by mechanical stretch.

On the basis of in vivo animal studies and on experiments of nature, it has been suggested that fetal breathing movements are essential for normal lung growth in utero. To study this hypothesis in vitro, we examined the effect of mechanical stretch on proliferation of fetal rat lung cells maintained in organotypic culture to provide a three-dimensional matrix. Initial studies demonstrated that stretch-mediated effects on cell division and DNA synthesis in such cultures were influenced by cell inoculation density, fetal calf serum concentration, and by the amplitude, frequency, periodicity, and duration of the applied stretch. After a 48-h exposure to an intermittent stretch pattern (5% elongation, 60 stretches/min for 15 min of each hour), cell number increased 10% (P less than 0.05), cell doubling time was reduced from 71 to 55 h (P less than 0.05), [3H]thymidine incorporation into DNA increased 61% (P less than 0.01), and the [3H]thymidine-labeling index increased 2.8-fold (P less than 0.001) compared with nonstretched controls. This effect did not appear to be mediated by prostaglandins or leukotrienes because the prostaglandin synthase inhibitors ibuprofen (2.5-50 microM) or BW 755C (5 microM), leukotriene biosynthesis inhibitors BW 755C (5 microM) or MK-886 (0.3 microM), and leukotriene D4 receptor antagonist MK-571 (0.3 microM) did not block stretch-mediated effects. We conclude that mechanical forces act directly to stimulate fetal rat lung cell growth and that these results are compatible with a significant role for fetal breathing in normal fetal lung growth.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Computerized plotting of low skin impedance points.

The distribution of low skin impedance points (LSIP) was studied on 68 subjects with a computer system designed for the measurement of skin impedance. The results demonstrated that LSIPs were basically distributed along the 14 channels, the overwhelming majority located right on or within 5 mm bilaterally to their courses. LSIPs were found in the area between every two channels only in a few cases. Moreover, there was no marked natural fluctuation of skin impedance in the human body and the distribution of LSIPs was considerably stable, which could be plotted on any day in the experiment. It is clear that such particular distribution of LSIPs along channels was really a biological phenomenon, not an experimental error. However, the distribution of low skin impedance was not an uninterrupted solid line but a series of LSIPs basically along the channel course. The method used in this work was accurate, reliable and repeatable which has upgraded the measurement of LSIPs to a new level. Under certain conditions, skin impedance can be used as an objective index in channel research.

Adult↗
PubMed1992

[Photoocclusion analysis for the reduction of occlusal table dimension of the pontics].

50 cases of mandibular dentitions with normal morphology and occlusion are analyzed by using photoocclusion. The occlusal surfaces of the molars are divided into four regions buccolingually. That are the buccal inclines and lingual inclines of the buccal and lingual cusps of the molars. The relationship of sigma epsilon value among these four regions is 3:5:2:0 respectively. This indicates that it is effective to get force reduction by adjusting the buccal incline of the pontic in fixed bridge restoration.

Biomechanical Phenomena↗
PubMed1992

[Research on sterilization of pathogens by high electrostatic voltage method].

An experimental research has been carried out on the sterilization of four kinds of pathogens by high electrostatic method along with an inquiry into the influence of voltage waveform and the treated time on sterilization. It is concluded that pathogens can be killed efficiently by corona discharge field.

Candida albicans↗
PubMed1992

[Studies of distribution of subtypes of transferrin, group-specific component, alpha 1-antitrypsin in gastric cancer patients from Shanghai area].

The genetic polymorphism of transferrin (Tf) and alpha 1-Antitrypsin (alpha 1-AT) in 202 gastric cancer patients and 202 controls in Shanghai Hans were analyzed by isoelectric focusing. In transferrin, the phenotype frequency of C1C1 and gene frequencies of c1 and c2 were 0.3713, 0.5718 and 0.4109 respectively in gastric cancer patients, and 0.5149, 0.6782 and 0.2970 separately in controls. The frequencies of the c1c1 phenotype and the C1 gene increased significantly (p < 0.01) among the controls, while the frequency of the C2 gene greatly increased (p < 0.01) among the patients. The frequencies of the C2C2 in gastric cancer patients and controls were 0.2228 and 0.1436 respectively, showing a significant difference between them (p < 0.05). The genetic polymorphisms of group-specific component (Gc) in 200 gastric cancer patients and 200 controls in Shanghai Hans were studied with isoelectric focusing followed by immunofixation. The Gc1F1F phenotype frequency and 1Fgene frequency were 0.22 and 0.4375 in gastric cancer patients, and 0.14 and 0.3600 in controls, respectively. The frequencies of the Gc1F1F phenotype and the 1F gene were significantly increased (p < 0.05) among the patients. In alpha 1-Antitrypsin, there was no significant difference in phenotype frequencies and gene frequencies between the patients and controls. The data reported here indicate that the gastric cancer is associated positively with TfC2 and Gc1F, and negatively with TfC1. These facts support the notion that cancerogenesis is a multi-step process controlled by multifactorial inheritance.

Adult↗
PubMed1992

Utilization of the protoplast fusion technique to explore directional altering lincomycin producing microorganism.

Interspecific protoplast fusion between Streptomyces lincolnensis var. lincolnensis (LM gamma, CTC gamma, producing lincomycin) protoplast and Streptomyces aureofaciens (LM gamma, CTC gamma, producing chlorotetracycline) protpolast which had been treated with UV radiation 40 min for inactivation was performed with PEG 6000, the fusants were obtained by directly selecting from the regeneration plates containing CTC 50 micrograms/ml, the fusion frequency was about 9.05 x 10(-5). From many fusants, only 4 stable recombinants were obtained. These species produced antibiotics which are different from lincomycin and chlorotetracycline. Preliminary identification of the antibiotic synthesized by one of the recombinants suggests that its basic structure might be similar to that of lincomycin. The fermentation product of recombinant No. 2 showed new chromatographic spot which is similar to that of clindamycin. Though the products remain to be identified further, this strategy seems to be worthy of exploring for screening new antibiotics.

Anti-Bacterial Agents↗
PubMed1992

[The immunologic studies on experimental heterogeneous penetrating keratoplasty].

Using the experimental model of chicken-rabbit penetrating corneal grafting, micro-whole-blood 3H-TdR incorporation and ELISA the authors dynamically observed the functional state of cellular and humoral immunities for 10 weeks after operation. The results showed, (1) In both the homogroup and the hetero-group, the transformational degree of lymphocytes in peripheral blood increased, most obviously in the 3rd or 4th week postoperatively. (2) In the hetero-group, specific anti-corneal antibody appeared obviously in the serum during 2-8 weeks postoperatively. Combined with morphologic observation, it has proved that: (1) The immune rejection is mainly cellular mediated immunoresponse, meanwhile, the humoral immunoresponse also participates in it, and the humoral immunoresponse participates in the heterokeratoplasty more obviously. (2) Applying the micro-whole-blood 3H-TdR incorporation is capable of determining the immunologic state of the body after corneal transplantation. (3) Attention should be focused on the 3-4 week period postoperatively when immunosuppressive-agent is administered.

Animals↗
PubMed1992

[Effects of tetramethylpyrazine and ferulic acid alone or combined on vascular smooth muscle, blood viscosity and toxicity].

The experiments showed that both tetramethylpyrazine and ferulic acid relaxed the norepinephrine-induced spasmodic contraction of rabbit and rat aorta strips, increased the coronary flow of isolated guinea pig hearts and reduced the whole blood viscosity in rats. Evaluated with Burgi's equation, the combined effect of these 2 drugs was obviously potentiated, but the combined acute toxicity in mice was greatly reduced.

Animals↗
PubMed1992

Adenosine's role in the genesis of bradyarrhythmias induced by acute myocardial hypoxia.

A close or even causal relation between myocardial adenosine and bradyarrhythmias during acute myocardial hypoxia was testified in guinea pig, rabbit and dog mainly by using specific competitive antagonist and synchronous quantitative analysis of 3 variables: intensity of myocardial hypoxia, degree of endogenous adenosine increment and severity of bradyarrhythmias. Results disclosed: A) striking resemblance of the bradyarrhythmias with hypoxic origin to those caused by exogenous adenosine, B) same locality of A-V conduction block induced by both myocardial hypoxia and exogenous adenosine, C) precise parallelism among the above-listed 3 variables with very high correlativity (r = 0.99, P < 0.01), D) frequent accompaniment of reversal of hypoxic bradyarrhythmias through resupply of 21% O2 with normalization of preexisted increase in myocardial adenosine, E) satisfactory blockade of hypoxic bradyarrhythmias by adenosine's specific antagonist--aminophylline and their augmentation by adenosine's uptake inhibitor--dipyridamole, F) close similarity of the characteristic curve representing relation among the above 3 variables to that among intensity of myocardial hypoxia, degree of endogenous adenosine increment and amount of coronary blood flow in which adenosine's role as a mediator has been well documented and G) reproducible persistence of bradyarrhythmias during myocardial hypoxia irrespective of preliminary vagotomy and atropinization, denoting independence of the occurrence of such dysarrhythmias upon vagal drive, suggestive of a mechanism other than vagotonia. We advocated that hypoxia-induced bradyarrhythmias was caused by increment in endogenous adenosine.

Adenosine↗
PubMed1992

[Survey and treatment of the blind in Xinhui, Guangdong, China].

Co-operating with Helen Keller International (HKI) in 1987 and 1988, Zhongshan Ophthalmic Center made a large scale prevalent survey of the blind in Xinhui, Guangdong, China. Three screening methods were used in the project. The first was a house-to-house visit by ophthalmologists. The second was performed initially by trained country health workers and then checked by ophthalmologists. In the third one, the blind people were asked to come together to be examined by ophthalmologists. The second method was found to be the most effective. The survey revealed that the prevalent rate of blindness was 0.24% in the county. Of all the blind, 89% were over 50 years old, 73% were females. Cataract accounted for 47% of the blindness. Thirty percent of the blind from cataract received surgical treatment. The postoperative re-examination half a year later showed that the corrected visual acuity in 86% of the patients was more than 0.05.

Aged↗
PubMed1992

Inoculation of pigs with Streptococcus suis type 2 alone or in combination with pseudorabies virus.

Pigs (9 [+/- 1] weeks old) were inoculated with Streptococcus suis type 2, pseudorabies virus (PRV), or both. For each pig of groups A, B, and C the inoculum of S suis was 10(9) colony-forming units. For each pig of groups A, B, and D the inoculum of PRV was 5 x 10(3) TCID50 of either PRV strain 4892 (group A, n = 9) or PRV isolate B (group B, n = 9). The PRV strain 4892 is a highly virulent strain; isolate B causes mild clinical signs of infection in inoculated pigs. Group-C pigs (n = 9) were given S suis alone, and group-D pigs (n = 3) were inoculated only with PRV isolate B. Clinical signs of infection and development of lesions were readily seen in pigs of groups A, B, and C. Duration and severity of clinical signs of disease and lesions were reduced in pigs of group C, compared with those of the other 2 groups. Lesions, such as polyarthritis and fibrinous pericarditis, were more abundant and acute in the groups of pigs given mixed challenge exposure, compared with pigs inoculated exclusively with S suis type 2 (group C). The group of pigs inoculated with PRV isolate B alone did not manifest clinical signs of disease or lesions. Average daily gain for group-C pigs was higher, compared with that of other groups; the difference was statistically significant at P less than 0.02 and P less than 0.05 for groups B and D, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

[126 small gestational age infants. Clinical characteristics and long-term observation].

From January 1, 1987 through June 30, 1990, 126 infants of small gestational age (SGA) born in our hospital were studied prospectively. The incidence of SGA infant > or = 37 weeks was 71.4%. The incidence of very low birth weight infants was only 6.3%. The incidence of birth asphyxia in this group (14.9%) was 3 times higher than that in full term infants; this incidence showed negative correlation with gestational age and birth weight. The morbidity rates of hypoglycemia (25.7%) and polycythemia (10.1%) were much higher than those in AGA infants. Malformation was the major cause of death in SGA infants. The mortality rate of SGA infant was 5.6% and the mortality rate of SGA infant > or = 37 weeks was only 1.1%. The results of follow-up showed that the physical development was normal in about 90% of cases at 2 years of age, and only 2 cases had low motor development scale when they were one-year old.

Asphyxia Neonatorum↗
PubMed1992

[Determination of sugar components in wild and cultured sclerotia of Grifola umbellata (pers. ex Fr.) Pilat at different ages].

Our determination indicates that in both wild and cultured sclerotia of Grifola umbellata the contents of reducing sugar decrease with the growing years; the contents of Polysaccharide peak in the second year of growth; the contents of protein increase with the growing years; the contents of fat reaches maximum in the first year of growth; in cultured sclerotia ergosterol becomes highest in contents when the plant is two years old, while in wild sclerotia it remains lowest.

Ergosterol↗
PubMed1992

Comparative study of 99mTc-HM-PAO SPECT brain imaging, EEG and CT scanning in epileptic patients during the interictal period.

Forty patients with epilepsy in the interictal period were studied with 99mTc (HM-PAO) SPECT brain imaging, EEG and CT scanning. Four cases of generalized epilepsy had normal findings on EEG, SPECT imaging and CT scanning. Two cases of childhood benign partial seizures had abnormal EEG, but the SPECT brain imagings were normal. Regional hypoperfusions of various extents were found in 20 of the 34 patients with complex partial seizures. Among the 34 patients, 17 had abnormal EEG and 8 had abnormal CT scans. A good topographic concordance between regional HM-PAO hypofixation and EEG foci was found (39.1%). Localization of the lesion by SPECT imaging and CT scan was coincident in 5 cases (27.8%). The correlation between these three examination methods is discussed.

Adolescent↗