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Biomedical subjects

K Xu

Publications and source records attributed to K Xu.

At least 235 records · Page 13Linked to original sources
PubMed1992

[Facilitatory effect of Pinellia ternata lectin on quantal release of acetylcholine from nerve terminals].

Pinellia ternata lectin (PTL) extracted from the rhizome of Pinellia ternata Briet by porcine thyroglobulin-Sepharose 4B column exhibits hemagglutination activity and carbohydrate binding specificity for mannan. Here we reported the effects of PTL on the resting membrane potential of muscle fiber and on the release of acetylcholine (ACh) from the motor nerve terminals in the phrenic nerve diaphragm preparations of mice. The results showed that PTL increased the frequency of miniature end-plate potential (MEPP). In 30 min after the treatment of the preparation with lectin 100 micrograms.ml-1, the frequency of MEPP reached 20 times higher than that of the control. Addition of mannan 1 mg.ml-1 restored the raised discharge of MEPP to its control level immediately. Similar to the effect of PTL on MEPP frequency, the amplitude and mean quantal content of end-plate potential also increased after PTL. At 100 micrograms.ml-1, the lectin depolarized the muscle membrane slightly, while at 10 micrograms.ml-1 no effect on the membrane potential was found. These results were interpreted as the intracellular Ca2+ elevation due to a permeability increase of the nerve terminal to ions after PTL.

Acetylcholine↗
PubMed1992

Diagnostic value of serum gamma-glutamyl transferase isoenzyme for hepatocellular carcinoma: a 10-year study.

Serum gamma-glutamyl transferase (GGT) was separated into nine to 11 isoenzyme bands (designated as GGT I-XI) by vertical slab electrophoresis on polyacrylamide gradient gel. The diagnostic value of GGT isoenzyme II (GGT II) for hepatocellular carcinoma (HCC) was studied, and the results were as follows: 1) GGT II was positive in 90% of 90 cases of HCC, and negative in most patients with acute and chronic viral hepatitis, extrahepatic tumors, in pregnant women, and in healthy controls; 2) the positive rate of GGT II assay was higher than that of alkaline phosphatase isoenzyme I (ALP I), alpha-fetoprotein (AFP), and alpha 1-antitrypsin (AAT) in 101 cases of HCC. In cases in which the AFP was greater than 50 ng/ml or less than 50 ng/ml, the positive rates of GGT II were 70.8% and 75-100%, respectively; 3) of 14 cases of small-size HCC, the positive rate of GGT II was 78.6%, which was higher than that of AFP (50%), AAT (28.6%), and ALP I (0%); 4) of 62 cases that were false-positive for GGT II assay, 24.2% developed into HCC during a follow-up of 2.1-20 months. In subjects with persistent and recurrent positivity of GGT II, 86.7% and 22.2%, respectively, developed HCC. No patient with temporal positivity of GGT II developed HCC. The results show that GGT II can be applied as an additional marker for HCC, and is valuable not only for the diagnosis of clinical HCC, but for the detection of small or subclinical HCC. Periodic follow-up with assay of GGT II in patients at high risk for HCC may predict the development of hepatoma.

Biomarkers, Tumor↗
PubMed1992

[Stability of shuang huanglian aerosol].

The contents of chlorogenic acid and baicalin in shuang huanglian aerosol were determined by HPLC. The process of chemical kinetics of the aerosol was studied by constant temperature acceleration tests, and the stability of the drug predicted. The results appeared close to those from the stored sample method. pH changes during degradation of the drug were also observed.

Aerosols↗
PubMed1991

[Study on morbidity and relative factors of postmenopausal osteoporosis in 340 women in Chengdu].

In this cross-sectional study, the radius bone mineral content (BMC) of 340 postmenopausal women (mean age: 53; mean years since menopause: 5.56) were assessed by single photon absorptiometry (SPA) for determining prevalence rate of postmenopausal osteoporosis in Chengdu, and some factors relative to BMC were investigated. Eighty-five of 340 postmenopausal women were diagnosed osteoporosis by SPA. The prevalence rate, which increases with year since menopause and age, is 25%. There is significant increase in prevalence after the age of 60 years or 5 years since menopause. Sixteen factors were analysed by STEPWISE REGRESSION. The variables selected were serum calcium(SCa), serum alkaline phosphatase (SAkP), urine calcium (UCa), urine hydroxypoline (UH), age, and Para. Fisher DISCRIMINANT ANALYSIS was used for diagnosis with these variables, the accuracy of diagnosis being 75.2%. Our study showed that postmenopausal osteoporosis is a common disease in Chengdu. High SCa, UH, age and low SAkP level may be risk factors of osteoporosis.

Adult↗
PubMed1991

Experimental borderline lepromatous leprosy with intraneural erythema nodosum leprosum in a mangabey monkey (Cercocebus atys).

A sooty mangabey monkey (Cercocebus atys) was inoculated with Mycobacterium leprae and developed borderline lepromatous leprosy and intraneural erythema nodosum leprosum. Previously studied mangabeys have developed only disseminated lepromatous leprosy without reactions. This case broadens the spectrum of leprosy seen in experimentally inoculated animals and further characterizes the nonhuman primate model of leprosy.

Animals↗
PubMed1990

[Balloon angioplasty treatment of patients with Budd-Chiari syndrome].

Fourteen cases with membranous or segmental stenosis or obstruction of the inferior vena cava (11 cases) and the hepatic vein (3 cases) associated with Budd-Chiari syndrome were successfully treated by PTA. The average width of veins was increased from 2.5 mm to 14.9 mm. The average pressure of veins dropped from 21.2 +/- 1.9 mmHg of pre-PTA to 15.7 +/- 2.6 mmHg immediately after PTA. Significant improvement (p less than 0.001) was obtained. In 9 cases reexamined after PTA, the pressure of vein dropped further from 16.9 +/- 1.5 mmHg immediately after PTA to 10.4 +/- 2.1 mmHg. Thirteen cases were followed up for an average of 9 months (range 6-16 months). The complete recovery of clinical symptoms was seen in 7 cases. The symptoms were evidently improved in 5 cases. The symptoms was relieved in one patient. Re-stenosis of the inferior vena cava occurred in only one patient after 4 months of PTA. In conclusion, (1) PTA with balloon catheter is a safe and effective method of treatment, and the method is extensively appreciated for this syndrome. (2) The clinically effective results of treatment is obtained immediately after PTA for Budd-Chiari syndrome. (3) Brockenbrough method was considered to have good indication to the membranous as well as segmental obstruction of Budd-Chiari syndrome.

Adult↗
PubMed1990

Assessment of damage from implantation of microdialysis probes in the rat hippocampus with silver degeneration staining.

We used a sensitive silver degeneration staining method to study the effects of insertion of microdialysis probes in rat dorsal hippocampus and neocortex. Nine animals were sacrificed 24 h, 3 days or 7 days after implantation of dialysis tubing. Although mild neuronal cell death and small petechial hemorrhages were seen in close proximity to the implantation site, the striking finding was the presence of degenerating axons both adjacent to the implantation site and in remote sites such as the corpus callosum and contralateral hippocampus. The observed changes could alter brain function near or remote from the implantation site and should be considered in analysis of dialysis experiments.

Animals↗
PubMed1990

Lack of the blocking effect of cobrotoxin from Naja naja atra venom on neuromuscular transmission in isolated nerve muscle preparations from poisonous and non-poisonous snakes.

Neuromuscular transmission in the Chinese cobra Naja naja atra was not affected by its own toxin (cobrotoxin) at a concentration of as high as 100 microM, while in the frog a concentration of less than 0.1 microM cobrotoxin depressed the amplitude of the end-plate potential to less than 10% of its original value within 30 min or directly blocked the nerve-evoked muscle action potential. The lack of effect of cobrotoxin was also observed in the nerve-muscle preparations from a pit viper (Agkistrodon blomhoffii brevicaudus) and three species of non-poisonous snakes (Elaphe dione, Elaphe bimaculata and Elaphe rufodorsata). On the other hand, the snake preparations were sensitive to the blocking effect of D-tubocurarine and less sensitive to that of atropine, indicating that the nicotinic acetylcholine receptor is responsible for transmission between the nerve and the skeletal muscle of the snake. We suggest that the snake nicotinic cholinergic receptor lacks the cobrotoxin binding-site.

Action Potentials↗
PubMed1990

Antibodies to lipoarabinomannan antigen in sooty mangabey monkeys experimentally inoculated with Mycobacterium leprae.

IgG and IgM antibody levels to mycobacterial lipoarabinomannan (LAM) antigen were determined by ELISA in eight sooty mangabey monkeys (Cercocebus atys) prior to and at intervals after experimental inoculation with Mycobacterium leprae. High levels of anti-LAM IgG were present before inoculation and increased thereafter in the five mangabeys that developed lepromatous (LL) forms of leprosy; lower levels of anti-LAM IgG were observed in two mangabeys that developed indeterminate leprosy and tuberculoid/neuritic leprosy, respectively, and in a mangabey that was leprosy resistant. IgM anti-LAM levels were near zero before M. leprae inoculation in all eight animals, rose significantly in only three LL-leprosy-susceptible animals after inoculation, and returned to near zero in all animals within 3 years. Anti-LAM antibody levels appear to be potentially valuable as an indicator of leprosy susceptibility, and when measured longitudinally together with antibody levels to M. leprae-specific phenolic glycolipid-I antigen, as a means to detect preclinical M. leprae infections in high-risk individuals.

Animals↗
PubMed1989

Evidence for the progressive and adaptive nature of spontaneous transformation in the NIH 3T3 cell line.

The NIH 3T3 mouse cell line is widely used as a recipient of DNA from tumors to demonstrate the presence of transforming oncogenes. We show that these cells produce transformed foci spontaneously if kept in the confluent state for more than 10 days. The formation of foci depends on the type and concentration of bovine serum used in the medium and passage history of the cells. Cells maintained in continuous exponential multiplication in the subconfluent state by transfer every 2-3 days in medium with 10% calf serum failed to develop the capacity to produce foci in 2% calf serum, but those transferred the same way in 2% calf serum or in 10% fetal bovine serum, which is a less potent growth stimulant, did develop that capacity to an increasing degree over time. The number of transformed cells increased sharply with the time that a culture remained in the confluent state. There are several morphological types and degrees of transformation, which indicates that the underlying changes are varied and the process is progressive. The results also suggest that transformation occurs in a fraction of an entire cell population that is undergoing a physiological adaptation to moderate constraints on its growth.

Animals↗
PubMed1989

Amino acid sequence of a presynaptic neurotoxin, agkistrodotoxin, from the venom of Agkistrodon halys Pallas.

The amino acid sequence of a presynaptic neurotoxin, agkistrodotoxin (ATX) isolated from the venom of Agkistrodon halys Pallas, was determined by automated Edman degradation and the carboxypeptidase digestion of the S-carboxymethylated ATX and by sequence analyses of peptides produced with cyanogen bromide cleavage and with trypsin or staphylococcal V8 protease digestion of the S-carboxymethylated ATX. ATX consists of 122 amino acid residues, including the histidine residue and 14 half-cystine residues. The amino acid sequence of ATX is very similar to those of toxic phospholipases and the phospholipase subunits of presynaptic neurotoxins from snake venoms. The residues responsible for the toxic activity of the presynaptic neurotoxins are discussed.

Amino Acid Sequence↗
PubMed1989

[Studies on mechanism of carcinogenesis in cell culture. III. Butyric acid-induced phenotypic reversion of malignant transformed Syrian hamster lung cells (BHLB4)].

The MNNG transformed Syrian hamster lung fibroblast cell line (BHLB4) established in our laboratory was treated with 2.0 mmol/L butyric acid. We obtained a butyric acid-dependent partially reversed cell line (ButB4) similar to normal cells in morphology, membrane properties, proliferation rate, colony-forming ability on solid agar culture, etc. However, when transplanted into nude mice, this cell line's tumorigenicity remained intact. Detection of cAMP levels in the cytoplasm showed much higher levels in ButB4 cells than in transformed cells. Butyric acid activity is evidently associated with changes of cAMP. In addition to phenotypical analysis, the karyotypes of ButB4 and BHLB4 were analyzed in detail. It was found that the disomy rate of C15 was significantly increased in ButB4 cells (73%) as compared with BHLB4 cells (33%). These results show that butyric acid not only induces phenotypic reversion in BHLB4 cells directly, but can also selectively kill C15 monosomy cell clones, allowing rapid growth of C15 disomy cell clones. Butyric acid may also influence maintenance of the reversion phenotype.

Animals↗
PubMed1989

[Studies on cell surface fibronectin of transformed Syrian hamster lung cells induced by butyric acid].

In this paper, Fn was analysed qualitatively and quantitatively in three Syrian hamster cell lines, ie, nontransformed baby hamster lung fibroblasts cell line (BHL), a transformed cell line (BHLB4) and a butyric acid-induced phenotypically reversed cell line (ButB4) respectively. Fn was visualized on cell surface by means of indirect immunofluorescence technique. Immunofluorescence of Fn on the surface of BHL was bright with a stripe-like distribution, while that on the surface of BHLB4 was very dim or dispersed. On ButB4 cell surface, the intensity and distribution of immunofluorescence was similar to that on BHLB4 cells. Fn was isolated by affinity chromatography from the cell surface of the three cell lines. Its molecular weight was 250 kDa on SDS-polyacrylamide electrophoresis. The quantity of Fn isolated from surface of ButB4 was a bit lower than that from BHL, but was much higher than that from BHLB4. The result offers us a useful criterion for transformation and reverse transformation.

Animals↗
PubMed1989

The effect of macrophage-conditioned medium on metabolism of normal very low density lipoprotein by fibroblasts.

Triglyceride was accumulated saturably in cultivated human fibroblasts exposed to increasing concentration of normal very low density lipoprotein (N-VLDL). Characterization of binding and degradation of 125I-N-VLDL by the cells indicated a direct uptake of intact N-VLDL particles via the cell surface receptor. Competition of unlabelled N-VLDL and LDL with 125I-N-VLDL in fibroblasts suggested that LDL receptor may be involved in this process. An unsaturable triglyceride accumulation in fibroblast induced by macrophage-conditioned medium containing N-VLDL was also observed. Intracellular triglyceride content, in this case, is linearly correlated with the concentration of N-VLDL in the medium and results mainly from re-esterification of fatty acid produced by hydrolysis of VLDL-triglyceride by lipoprotein lipase of macrophage.

Boronic Acids↗