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Biomedical subjects

X Cui

Publications and source records attributed to X Cui.

At least 37 records · Page 2Linked to original sources
PubMed1995

[Analysis of 100 cases of precancerous laryngeal lesions].

Hundred cases of precancerous laryngeal lesions were analysed on the basis of clinical pathology. The results showed that there was close relationship between the precancerous laryngeal lesions and voice abuse and long-term heavy smoking. The pathology showed epithelial hyperplasis and mild to severe atypical hyperplasia (heterotype). Scanning electronmicroscopy revealed that the more severe the degree of the epithelial heterotype, the more pleomorphic the shape of cell morphology, margin. Twenty cases had malignant changes later, and the rate of malignant change was high in those with atypical hyperplasia. Some lesions which were taken for polyps clinically and pathologycally could also have malignant changes, so more attention should be paid to these lesions during clinical management.

Adolescent↗
PubMed1994

Spinal serotonin IA and IC/2 receptors mediate supraspinal mu opioid-induced analgesia.

Intracerebroventricular (i.c.v.) injection of highly selective mu opioid receptor agonist ohmefentanyl (OMF) to rats produced dose-dependent antinociception as assessed with the tail flick test. This analgesia could be blocked by intrathecal (i.t.) injection of the 5-HT1A receptor antagonist spiperone or the 5-HT1C/2 receptor antagonist mianserin, but not by the 5-HT2 receptor antagonist 1-NP or the 5-HT3 receptor antagonist ICS 205-930. The results suggest that the descending 5-HT system is involved in mediating spinal mu opioid analgesia via spinal 5-HT1A and 5-HT1C/2 receptors.

Analgesia↗
PubMed1994

Inhibition of the phosphoenolpyruvate:lactose phosphotransferase system and activation of a cytoplasmic sugar-phosphate phosphatase in Lactococcus lactis by ATP-dependent metabolite-activated phosphorylation of serine 46 in the phosphocarrier protein HPr.

Lactococcus lactis takes up lactose and the nonmetabolizable lactose analogue, thiomethyl-beta-galactoside (TMG), via the phosphoenolpyruvate:sugar phosphotransferase system (PTS) which couples sugar transport to sugar phosphorylation. Earlier studies had shown that TMG-phosphate, previously accumulated in L. lactis cells, is rapidly dephosphorylated in the cytoplasm and effluxes from the cells upon addition of glucose and that glucose inhibits further uptake of TMG. We have developed a vesicular system to analyze this regulatory mechanism and have used electroporation to shock proteins and membrane-impermeable metabolites into the vesicles. Uptake of TMG was dependent on an energy source, effectively provided by intravesicular phosphoenolpyruvate at low concentrations or extravesicular phosphoenolpyruvate at high concentrations. TMG uptake into osmotically shocked vesicles was only weakly inhibited, and expulsion of preaccumulated TMG was only slightly stimulated upon addition of glucose. Intravesicular (but not extravesicular) wild-type HPr of Bacillus subtilis completely restored the regulatory behavior observed in vivo when glucose was present in the external medium. Glucose could be replaced by intravesicular (but not extravesicular) fructose 1,6-diphosphate, gluconate 6-phosphate, or 2-phosphoglycerate, but not by other phosphorylated metabolites, in agreement with the allosteric activating effects of these compounds on HPr(Ser) kinase measured in vitro. Intravesicular mutant HPr(S46A) protein could not promote regulation of lactose permease activity when electroporated into the vesicles regardless of the presence or absence of glucose or the various phosphorylated metabolites, but the HPr(S46D) mutant protein promoted regulation, even in the absence of glucose or a metabolite, and HPr(H15A) was more effective than the wild-type protein in promoting regulation. Intravesicular wild-type and H15A HPrs, but not the S46A or S46D mutant proteins, were found to be phosphorylated by ATP under the conditions which promoted TMG efflux. In toluenized vesicles, the conditions which promoted TMG efflux also promoted TMG-P hydrolysis. These results establish for the first time that HPr serine phosphorylation by the ATP-dependent metabolite-activated HPr kinase regulates the expulsion of intracellular sugar-phosphate as well as the uptake of sugar via the PTS in L. lactis.

Adenosine Triphosphate↗
PubMed1994

ATP-dependent phosphorylation of serine-46 in the phosphocarrier protein HPr regulates lactose/H+ symport in Lactobacillus brevis.

Lactobacillus brevis takes up lactose and the nonmetabolizable lactose analogue thiomethyl beta-galactoside (TMG) by a permease-catalyzed lactose/H+ symport mechanism. Earlier studies have shown that TMG, previously accumulated in L. brevis cells, rapidly effluxes from the cells upon addition of glucose, and that glucose inhibits further uptake of TMG. We have developed a vesicular system to analyze this regulatory mechanism and have used electroporation to shock proteins and membrane-impermeant metabolites into the vesicles. Uptake of TMG was dependent on an energy source, effectively provided by intravesicular ATP or extravesicular arginine. TMG uptake into these vesicles was not inhibited, and preaccumulated TMG did not efflux from them upon addition of glucose. Intravesicular but not extravesicular wild-type phosphocarrier protein HPr of Bacillus subtilis restored regulation. Glucose could be replaced by intravesicular (but not extravesicular) fructose 1,6-bisphosphate, gluconate 6-phosphate, or 2-phosphoglycerate, but not by other phosphorylated metabolites, in agreement with the allosteric activating effects of these compounds on HPr(Ser) kinase measured in vitro. Intravesicular serine-46-->alanine mutant HPr cold not promote regulation of lactose permease activity when electroporated into the vesicles with or without glucose or the various phosphorylated metabolites, but the serine-46-->aspartate mutant HPr promoted regulation, even in the absence of glucose or a metabolite. HPr(Ser-P) appears to convert the lactose/H+ symporter into a sugar uniporter. These results establish that HPr serine phosphorylation by the ATP-dependent metabolite-activated HPr kinase regulates lactose permease activity in L. brevis. A direct allosteric mechanism is proposed.

Adenosine Triphosphate↗
PubMed1994

A chromosome painting method for human sperm chromosomes using fluorescent in situ hybridization.

A method of chromosome painting on human sperm chromosomes using fluorescent in situ hybridization (FISH) is introduced. Sperm chromosome slides were prepared after in vitro fertilization of hamster eggs with human spermatozoa. The slides were treated by RNase A before FISH. Chromosome 4 was clearly and specifically painted in a majority of sperm-derived metaphase plates after an application of whole chromosome painting DNA probes of this chromosome. This is the first report of successful painting on human sperm chromosomes.

Animals↗
PubMed1994

Binding to and killing of human renal epithelial cells by hemolytic P-fimbriated E. coli.

Acute pyelonephritis is a common invasive infection frequently caused by E. coli that possess P-fimbriae and secrete hemolysin. We have examined the role of P fimbriae and hemolysin in the killing of putative target cells of acute pyelonephritis, that is, human renal epithelial cells (HRPTEC). Cultures of HRPTEC were overlaid with (1) a prototypic pyelonephritogenic E. coli (CFT073) which expresses both P fimbriae and hemolysin; (2) its hemolysin-negative isogenic mutant (CFT073hlyD::TnphoA); or (3) a prototypic nonpyelonephritogenic fecal E. coli (FN414) which is negative for both P fimbriae and hemolysin. CFT073 and CFT073hlyD::TnphoA but not FN414 adhered to HRPTEC, as demonstrated by electron microscopy and direct counting. Adherence was diminished by antisera directed against P fimbriae and by a monoclonal antibody recognizing the epithelial receptor for P fimbriae. CFT073 was significantly more cytolethal for HRPTEC than its hemolysin-negative mutant. The bacteria-free filtrate of CFT073 was both hemolytic and cytolethal whereas that of CFT073hyD::TnphoA was not hemolytic and was significantly less cytolethal. Finally, we demonstrated that CFT073 passed through monolayers of HRPTEC at a higher rate than CFT073hlyD::TnphoA, indicating that hemolysin damages HRPTEC, facilitating passage of bacteria through the epithelial barrier. With HRPTEC and a pyelonephritogenic strain of E. coli we have reproduced in vitro bacterial attachment and toxin delivery by P fimbriae and hemolysin, factors epidemiologically associated with acute pyelonephritis in patients.

Bacterial Adhesion↗
PubMed1994

Regulation of the glucose:H+ symporter by metabolite-activated ATP-dependent phosphorylation of HPr in Lactobacillus brevis.

Lactobacillus brevis takes up glucose and the nonmetabolizable glucose analog 2-deoxyglucose (2DG), as well as lactose and the nonmetabolizable lactose analoge thiomethyl beta-galactoside (TMG), via proton symport. Our earlier studies showed that TMG, previously accumulated in L. brevis cells via the lactose:H+ symporter, rapidly effluxes from L. brevis cells or vesicles upon addition of glucose and that glucose inhibits further accumulation of TMG. This regulation was shown to be mediated by a metabolite-activated protein kinase that phosphorylase serine 46 in the HPr protein. We have now analyzed the regulation of 2DG uptake and efflux and compared it with that of TMG. Uptake of 2DG was dependent on an energy source, effectively provided by intravesicular ATP or by extravesicular arginine which provides ATP via an ATP-generating system involving the arginine deiminase pathway. 2DG uptake into these vesicles was not inhibited, and preaccumulated 2DG did not efflux from them upon electroporation of fructose 1,6-diphosphate or gluconate 6-phosphate into the vesicles. Intravesicular but not extravesicular wild-type or H15A mutant HPr of Bacillus subtilis promoted inhibition (53 and 46%, respectively) of the permease in the presence of these metabolites. Counterflow experiments indicated that inhibition of 2DG uptake is due to the partial uncoupling of proton symport from sugar transport. Intravesicular S46A mutant HPr could not promote regulation of glucose permease activity when electroporated into the vesicles with or without the phosphorylated metabolites, but the S46D mutant protein promoted regulation, even in the absence of a metabolite. The Vmax but not the Km values for both TMG and 2DG uptake were affected. Uptake of the natural, metabolizable substrates of the lactose, glucose, mannose, and ribose permeases was inhibited by wild-type HPr in the presence of fructose 1,6-diphosphate or by S46D mutant HPr. These results establish that HPr serine phosphorylation by the ATP-dependent, metabolite-activated HPr kinase regulates glucose and lactose permease activities in L. brevis and suggest that other permeases may also be subject to this mode of regulation.

Adenosine Triphosphate↗
PubMed1994

[Effect of anti-fibronectin-serum on fertilization capacity of human spermatozoa].

Using the in vitro penetration test, we initially studied effects of anti-fibronectin (FN)-serum on fertilization capacity of human spermatozoa. Owing to the coincubation of anti-FN-serum in a heterologous system (human spermatozoa and zona-free gold hamster oocyte), a certain increase was found in the penetration rate at a low concentration of anti-FN-serum. The penetration rate in the treated group was 20% higher than that in the control group at an anti-FN-serum concentration of 10 microliters/ml (P < 0.05), but at a higher concentration of anti-FN-serum, the penetration rate was not affected. The results suggest that anti-FN-serum can improve the fertilization capacity of human spermatozoa, help to treat the unexplained infertility, and increase the repregnancy rate of vasovasotomy.

Animals↗
PubMed1994

[Cloning of T7 lysozyme gene and construction of the vector for transgenic plants resistant to bacterial infection].

DNA were extracted from bacteriophage T7 and digested partially with Ava II. T7 lysozyme gene was obtained by PCR. DNA sequence analysis showed that the nucleotide sequence of T7 lysozyme gene was 99.5% homologous with the reported sequence and its deduced amino acid sequence was the same as reported. DNA fragment encoding the signal peptide of the pathogenesis-related protein 1b(PR-1b) from tobacco and cecropin (Shiva-I) gene cloned in pUC19 were modified by PCR. The PR-1b signal peptide gene was fused respectively to the 5' terminals of T7 lysozyme gene and expression vector, so that T7 lysozyme gene and Shiva-I gene could express simultaneously in transgenic plants and the two gene products could be secreted to extracellular space.

Amino Acid Sequence↗
PubMed1993

Use of human renal proximal tubule cell cultures for studying foscarnet-induced nephrotoxicity in vitro.

Foscarnet is an antiviral agent used for the treatment of cytomegalovirus retinitis and acyclovir-resistant herpes simplex virus infections in AIDS patients. Renal impairment has been reported for many patients treated with foscarnet. We have studied the effects of foscarnet on the viability (estimated by neutral red inclusion) and ultrastructure of cultures of human renal proximal tubule cells (HRPTC) isolated from the kidneys of five cadavers and cultured. The degree of foscarnet-induced toxicity was dose dependent and varied among the HRPTC cultures. The data obtained by using the in vitro system of HRPTC mimic the data of the clinical trials in that there is a dose-dependent individual variation among human cases in response to foscarnet treatment. Thus, these cultures are extremely well-suited to investigations of the mechanism of toxicity at the subcellular level.

Adolescent↗
PubMed1993

Differential behaviour in pancreas and heart of two coxsackievirus B3 variants.

In order to characterize viral kinetics and pathogenic properties of two intratypic variants of coxsackievirus B type 3, Balb/c mice were intraperitoneally inoculated and serial samples harvested from days 2 to 28. Although both CB3o (amyocarditic) and CB3m (myocarditic) variants induced similar early infectivity titres in pancreas, only the latter led to severe acinar necrosis, followed in turn by patent viraemia and subsequent focal myocarditis. Nevertheless, when both variants were inoculated in cultured cardiac cells, neither infectivity nor cell death rate differed noticeable. Therefore, our findings indicate that overt myocarditis is not attributable to contrasting cardiomyocyte susceptibility to the tested variants but rather to prior viral events in pancreatic tissues.

Animals↗
PubMed1993

Schizophrenic delusions among Koreans, Korean-Chinese and Chinese: a transcultural study.

In this transcultural study of schizophrenic delusions among Koreans, Korean-Chinese and Chinese, many delusions were shown to be different among the three groups in their frequency and content and the differences could be explained by sociocultural and political factors. Delusional themes sensitive to influence by sociocultural or political situations and changes seem to be 'family', 'love affairs', 'religious matters', 'economic matters', 'specific physical damage' and 'political themes.' Delusions about 'family', 'love affair', 'being raped', 'religious matters' and 'economic and business matters' were most frequent in Koreans. Delusions of 'blood-relatedness', 'longevity' and 'political themes' were most frequent in Korean-Chinese. Delusions of 'bloodsucking and brain or viscera extracted' and 'poison or being pricked by poisoned needle' were most prominent in Chinese.

Adult↗
PubMed1993

[The role of hemorheologic disturbance in experimental acute pancreatitis].

The role of hemorheologic disturbance in experimental acute pancreatitis was studied in Wistar male rats. It was found that pancreatic duct obstruction with secretin stimulation could induce acute interstitial pancreatitis (AIP), but when high molecular dextran intravenous injection being added, acute necrotizing pancreatitis (ANP) was induced. The authors suggest that the high molecular dextran can increase blood viscosity, aggregation of erythrocytes and decrease erythrocyte deformability, which results in pancreatic microcirculatory disturbances and promotes progressive pancreatic necrosis. Hemorheologic disturbance is one of the key factors in the pathogenesis of ANP.

Acute Disease↗
PubMed1992

The bacteriocidal effects of transition metal complexes containing the NO+ group on the food-spoilage bacterium Clostridium sporogenes.

The chemical and molecular mechanism of toxicity of nitrite towards food-spoilage bacteria such as Clostridium botulinum or Clostridium sporogenes is not well understood. In order to discover the active species and explore its chemistry, a number of compounds related to nitrite were synthesized. Their bacteriocidal effects on C. sporogenes were investigated in Oxoid nutrient broth No. 2 growth medium at pH 7.0. Inhibition of cell growth, expressed as the concentration which causes 50% cell inhibition, was observed with nitrite at 10 mM, whereas [Fe4S3(NO)7]-(the anion of Roussin's black salt) and (Fe2(SCH2CH2OH)2(NO)4] (a water-soluble Roussin's red salt ester) were found to be effective at 0.001 mM and 0.005 mM, respectively, confirming previous reports that iron-sulphur-nitrosyl complexes are much more toxic to these organisms than nitrite itself. The nitroprusside anion, [Fe(CN)5NO]2- was found to be toxic at 0.030 mM and the corresponding chromium species, [Cr(CN)5NO]3-, at 0.1 mM. Therefore, on the basis of the number of NO groups present, the nitrosylcyano complexes are comparable in activity with the iron-sulphur-nitrosyl compounds. These results show that neither iron nor sulphur are essential for the bacteriostatic effect of the Roussin's type compounds. The property that all these compounds have in common is that they contain NO+. It is proposed that this is the active species responsible for the preservative effect of nitrite, and that a relationship may exist between the N-O stretching frequency, a measure of the NO+ character, and the toxicity of these NO(+)-containing complexes.

Clostridium↗
PubMed1992

Whole genome amplification from a single cell: implications for genetic analysis.

We have developed an in vitro method for amplifying a large fraction of the DNA sequences present in a single haploid cell by repeated primer extensions using a mixture of 15-base random oligonucleotides. We studied 12 genetic loci and estimate that the probability of amplifying any sequence in the genome to a minimum of 30 copies is not less than 0.78 (95% confidence). Whole genome amplification beginning with a single cell, or other samples with very small amounts of DNA, has significant implications for multipoint mapping by sperm or oocyte typing and possibly for genetic disease diagnosis, forensics, and the analysis of ancient DNA samples.

Base Sequence↗
PubMed1992

Gene-centromere linkage mapping by PCR analysis of individual oocytes.

We describe a general method of determining the recombination fraction between a polymorphic locus and the centromere in any species where single oocytes can be obtained. After removal of the first polar body, each oocyte is analyzed by PCR. The frequency of oocytes heterozygous at the polymorphic locus is used to estimate the recombination fraction. We estimate a recombination fraction of 0.15 between the mouse major histocompatibility complex (H-2) and the centromere of chromosome 17.

Animals↗