Biomedical subjects

L Yang

Publications and source records attributed to L Yang.

At least 451 records · Page 25Linked to original sources

PubMed1998

Transjugular intrahepatic portosystemic shunt: effect of bile leak on smooth muscle cell proliferation.

PURPOSE: To evaluate the effect of bile on smooth muscle cell (SMC) proliferation in vitro and in vivo in a porcine transjugular intrahepatic portosystemic shunt (TIPS) model. MATERIALS AND METHODS: In vitro, SMCs explanted from porcine thoracic aorta were cultured with standard techniques. After initial pilot studies, they were subcultured in one of three groups: 1% porcine serum plus 1% bile, 10% porcine serum plus 1% bile, and 10% porcine serum. Cells were harvested at 3, 10, or 14 days, and DNA, protein, and disintegrations per minute (an indicator of proliferation) were measured. In vivo, TIPS creation was successful in 45 swine. All pigs were euthanized at 10-16 days. The proliferative response within the stent was histologically quantified and correlated for evidence of bile leak. RESULTS: In pilot studies, 2.5%-10.0% bile solutions caused 100% SMC mortality by 3 days. In the presence of 1% bile (with or without porcine serum), both DNA and protein production decreased significantly compared with that in porcine serum alone (P < .05). In vivo, 13 of 45 specimens (29%) showed bile leak at gross or microscopic examination. SMC proliferation was less overall in animals with versus those without bile leak (difference not significant). CONCLUSION: These data suggest that the proliferative response in a TIPS is not primarily due to bile leak. Bile leak may promote thrombosis, but it appears to inhibit myointimal proliferation.

Animals↗

PubMed1998

Differential translocation of protein kinase C isozymes by phorbol esters, EGF, and ANG II in rat liver WB cells.

The protein kinase C (PKC) family represents an important group of enzymes whose activation is associated with their translocation from the cytosol to different cellular membranes. In this study, the spatial distribution of PKC-alpha, -delta and -epsilon in rat liver epithelial (WB) cells has been examined by Western blot analysis after subcellular fractionation. Cytosolic, membrane, nuclear, and cytoskeletal fractions were obtained from cells stimulated with phorbol 12-myristate 13-acetate (PMA), angiotensin II (ANG II), or epidermal growth factor (EGF). PMA caused most of the PKC-alpha, -delta and -epsilon initially present in the cytosol to be transported to the membrane and nuclear fractions. In contrast, both ANG II and EGF induced only a minor translocation of PKC-alpha to the membrane fraction but caused a statistically significant membrane-directed movement of PKC-delta and -epsilon. Translocation of PKC-delta and -epsilon to the nucleus induced by ANG II and EGF was transient and quantitatively smaller than that induced by PMA. PKC-delta and -epsilon were present in the cytoskeleton of resting cells, but although PMA, ANG II, and EGF caused some changes in their content, these were variable, suggesting that the cytoskeleton fraction was heterogeneous. PKC depletion inhibited ANG II-induced mitogenesis and the sustained activation of Raf-1 and extracellular regulated protein kinase (ERK). However, although PKC depletion inhibited EGF-induced mitogenesis, the maximum EGF-induced activation of the ERK pathway was only slightly retarded. We hypothesize that PKC-delta and -epsilon are involved in mitogenesis via both ERK-dependent and ERK-independent mechanisms. These results support the notion that specific PKC isozymes exert spatially defined effects by virtue of their directed translocation to distinct intracellular sites.

Angiotensin II↗

PubMed1998

Regulation of myosin heavy chain gene expression after short-term diaphragm inactivation.

Although prolonged diaphragm denervation (DNV) produces myofiber atrophy and a loss of type I myosin heavy chain (MHC) expression, short-term DNV leads to significant diaphragm hypertrophy. The purpose of this study was to explore the regulation of MHC isoform expression and muscle remodeling during DNV hypertrophy of the diaphragm. Both unilateral and bilateral DNV led to similar changes, with a significant increase in total RNA content and muscle mass but no change in dry-to-wet weight ratio. Sarcomere number was also increased in diaphragm myofibers after DNV ( approximately 20%), suggesting an adaptive response to muscle stretch. There was hypertrophy of type I myofibers and increased coexpression of type I and type II MHCs within single myofibers by immunocytochemistry as well as increased type I MHC (25-46%) and decreased type IIb MHC (14-39%) by SDS-PAGE. Contractility parameters were also consistent with a type II-to-type I MHC phenotype transformation. Importantly, DNV-induced modulation of MHC isoform mRNA transcript levels did not correspond to changes in their cognate proteins, suggesting a major degree of posttranscriptional control. We conclude that DNV hypertrophy of the diaphragm is associated with reciprocal changes in type I and type II MHC isoforms that are directly opposed to the type I-to-type II MHC phenotype transformation reported in the diaphragm DNV atrophy model. Furthermore, in contradistinction to most hypertrophy models, control of MHC gene expression and myofibrillar remodeling after short-term DNV appears to entail major involvement of posttranscriptional regulatory mechanisms.

Animals↗

PubMed1998

Resistance of pleural mesothelioma cell lines to apoptosis: relation to expression of Bcl-2 and Bax.

A failure of normal apoptosis, often due to mutant p53, may contribute to the formation of a cancer and to its resistance to therapy. Mesothelioma, an asbestos-induced tumor, is highly resistant to therapy but generally expresses wild-type p53. We asked whether mesothelioma was resistant to apoptosis and whether resistance was associated with altered expression of the antiapoptotic protein Bcl-2 or proapoptotic protein Bax. We found that three mesothelioma cell lines (1 with wild-type p53) were highly resistant to apoptosis induced by oxidant stimuli (asbestos, H2O2) or nonoxidant stimuli (calcium ionophore) compared with primary cultured mesothelial cells. By immunostaining, one of these three lines expressed Bcl-2 but only during mitosis. By immunoblotting, 3 of 14 additional mesothelioma lines (9 of 14 with wild type p53) expressed Bcl-2 but all 14 of 14 expressed the proapoptotic Bax, giving a low ratio of Bcl-2 to Bax. We conclude that mesothelioma cell lines are resistant to apoptosis and that the failure in apoptosis is not explained by Bcl-2 but by other mechanisms that counteract the proapoptotic effect of Bax.

Animals↗

PubMed1998

A murine skeletal muscle ischemia-reperfusion injury model: differential pathology in BALB/c and DBA/2N mice.

Ischemia-reperfusion injuries can occur with diseases such as myocardial infarction and stroke and during surgical procedures such as organ transplantation and correction of aortic aneurysms. We developed a murine model to mimic abdominal aortic aneurysm repair with cross-clamping of the aorta distal to the renal artery. After model development, we compared the normal complement BALB/c mouse with the C5-deficient DBA/2N mouse. To assess quantitative differences, we measured neuromuscular function up to 72 h after ischemia with a subjective clinical scoring system, as well as plasma chemistries, hematology, and histopathology. There were significant increases in clinical scores and creatine phosphokinase, lactate dehydrogenase, and muscle histopathology scores in BALB/c mice compared with those in DBA/2N mice and sham-surgery mice. Muscle histopathology scores of the cranial tibialis and quadriceps correlated well with clinical signs, creatine phosphokinase, and lactate dehydrogenase, and indicated the greatest pathology in these muscle groups. We developed a murine model of skeletal muscle ischemia-reperfusion injury that can utilize the benefits of murine genetic and transgenic models to assess therapeutic principles of this model. Additionally, we have shown a significant reduction in clinical signs, plasma muscle enzyme concentrations, and muscle pathology in the C5-deficient DBA/2N mouse in this model.

Animals↗

PubMed1998

Diaphragm sarcolemmal injury is induced by sepsis and alleviated by nitric oxide synthase inhibition.

Endotoxemia is associated with impaired diaphragm contractility, and increased nitric oxide (NO) production has recently been implicated in this phenomenon. However, the precise nature of sepsis-related alterations in diaphragm myofiber function remains unclear. We tested the hypothesis that enhanced NO synthesis during sepsis produces diaphragm sarcolemmal injury with attendant abnormalities of myofiber membrane electrophysiology. Two different rat sepsis models were employed: acute (4 h) intraarterial endotoxin (LPS; 20 mg/kg) and subacute (24 h) peritonitis induced by cecal ligation and perforation (CLP). Diaphragm damage occurred after both LPS and CLP, as indicated by hyperpermeability of myofibers to a low molecular weight tracer dye, which is normally unable to penetrate the sarcolemma. Sarcolemmal injury was significantly correlated with reductions in the resting membrane potential (Em) of single diaphragm myofibers. Western analysis revealed increased diaphragmatic expression of the inducible isoform of NO synthase (iNOS) after LPS and CLP. An inhibitor of NOS activity, LNMMA, significantly decreased morphologic as well as electrophysiologic signs of myofiber membrane injury and dysfunction. Therefore, we conclude that both acute endotoxemia and subacute peritonitis models of sepsis lead to significant sarcolemmal damage and altered Em in diaphragm myofibers. These changes appear to be mediated, at least in part, through the pathway of increased nitric oxide production.

Animals↗

PubMed1998

Transurethral prostate vaporization using an oval electrode in 82 cases of benign prostatic hyperplasia.

OBJECTIVE: To present our initial experience in transurethral vaporization of the prostate (TVP) using an oval electrode for the treatment of benign prostatic hyperplasia (BPH). METHODS: A total of 82 patients underwent TVP procedures with the oval electrode. The newly designed oval-shaped electrode can work with a High Frequency Electrosurgery Unit. Prostate gland tissue was vaporized through an Fr 24 percutaneous nephroscope transurethrally. The operation procedure was similar to transurethral resection of the prostate (TURP) or transurethral laser prostatectomy (TULP). Power setting ranged from 240 W to 320 W. Local vaporization temperature reached 120 degrees C. RESULTS: Urination was recovered in all 82 patients after TVP. Mean post-treatment International Prostate Symptom Score (I-PSS) reduced from 27.10 to 5.05; mean bladder residual urine volume dropped from 147.71 ml to 33.2 ml; and mean urine flow rate (MFR) increased from 4.45 ml/s to 14.57 ml/s (P < 0.01). The initial results of short-term follow-up were excellent. CONCLUSIONS: TVP with the oval electrode is easy to perform and causes less hemorrhage and few complications. It especially benefits elderly and/or critically-ill patients. We believe that TVP with our oval electrode is feasible with low risk.

Aged↗

PubMed1998

[Reconstruction of esophagus by microsurgical technique in forty-five cases].

Reconstruction and repair of atresia or defect of the upper portion of esophagus is difficult. From November 1980 to December 1997, forth-five cases, consisting 35 males and 10 females, were treated with microsurgical technique. The 45 patients fell into the following groups as esophageal atresia of various causes in 21 cases, anastomotic fistula or stenosis following reconstruction of esophagus in 7 cases and late carcinoma of esophagus in 17 cases. The types of reconstruction consisted of transfer of free jejunum with its lower portion carrying a vascular pedicle in 24 cases, free transfer of jejunal graft in 15 cases, free vascularized jejunal graft in 2 cases and free vascularized tubular skin graft in 4 cases. After a follow-up of 6-19 months besides eight cases died from late esophageal carcinoma, thirty-seven cases were survived and could take food by mouth. All of the benign cases could return to work. In patients having late esophageal carcinoma, the operative procedure could improve the life quality and facilitate chemotherapy and radiotherapy.

Adolescent↗

PubMed1998

Fast assay and mini-purification of protein by high performance membrane affinity chromatography.

Several affinity ligands of protein A, human immunoglobulin G, iminodiacetate (IDA)-Cu2+, and cibacron blue F3GA were coupled to GMA-modified cellulose membrane matrices. We prepared the columns based on the membrane supports in high performance membrane affinity chromatography (HPMAC). Next we evaluated nonspecific adsorption of proteins on the membrane media. The rapid assay of proteins on the affinity columns based on membrane supports was achieved. It was observed that the affinity columns based on membrane supports provided good reproducibility, high separation efficiency, and low pressure drop of the column. The columns with the membrane media could also be used for purification of proteins.

Adsorption↗

PubMed1998

[Study of ozonization effects on mineral water components].

The disinfection effects of ozonization and its influences on chemical components of mineral water were investigated. The results showed that ozone at the level of 0.5 mg/L and with the exposure time of 5 minutes effectively destroyed bacteria in mineral water. High level ozone showed no strong influences on some beneficial components, such as strontium and metasilicate and on some main components, such as bicarbonate, hardness and alkalinity, but slightly elevated pH value. Ozonization reduced the contents of total dissolved solids and oxygen demand, and decomposed some reductive contaminants such as ammonia, cyanide and phenols. Ozonization will convert part of the bromide into hypobromite and bromate.

Escherichia coli↗

PubMed1998

[Regulative effects pentagastrin and somatostatin on growth of human gastric cancer cells in vitro].

In order to observe the regulative effects of pentagastrin (PG) and somatostatin (SS) on the growth of two human gastric cancer cell lines (HGC803 and HGC823) in vitro, we observed the effects of PG and SS on proliferation of human gastric cancer cells by means of MTT. The contents such as gastrin, insulin, and glucagon were determined by radioimmunoassay (RIA), and the hexosamine content was determined by Neuhaus' method. The results showed that the growth of the two human gastric cancer cell lines were obviously promoted by PG. On the contrary, the growth and secretion of gastrin and glucagon were inhibited by SS. In addition, the hexosamine content of human gastric cancer cells was significantly increased by PG (7.58 +/- 0.66 versus 4.20 +/- 0.39 pg/cell, (P < 0.05). But the hexosamine content was decreased by SS (2.62 +/- 0.29 versus 4.20 +/- 0.39 pg/cell, P < 0.05). These findings indicate that the growth of gastric cancer cells is regulated by PG and SS, nevertheless a host of problems need to be elucidated.

Cell Division↗

PubMed1998

Activity of platelet in patients with high level of LDL and the effect of LDL on platelet glycoproteins.

OBJECTIVE: To investigate the activity of platelet in patients with high level of low density lipoproteins (LDL) and the effect of LDL on platelet glycoproteins (GP). METHODS: Platelet glycoproteins, whose platelet were activated or unactivated, were measured by flow cytometry. RESULTS: The amount of the platelet membrane GP II b/III a in patients was not significantly different from that of the control when platelet was unactivated (P > 0.05); when platelet was activated by adenosine diphosphate (ADP), the amount of patients' platelet GP II b/III a was increased markedly in comparison with that in the control (P < 0.01). Having been preincubated with LDL, the platelets were activated by ADP and the amounts of GP II b/III a of patients group and the control were all increased obviously as compared with those in the platelets which were not incubated with LDL (P < 0.01; P < 0.01). There was no significant difference of the amount of granule membrane protein-140 (GMP-140) between patients and the control when platelet was activated by thrombin (P > 0.05). Having been preincubated with LDL, platelet was activated by thrombin, the amounts of GMP-140 on patients' and control platelet were all increased markedly (P < 0.01, P < 0.01). CONCLUSION: The activity of platelet in patients with high level of LDL is increased significantly. LDL can increase the expression of platelet glycoproteins.

Adult↗

PubMed1998

[Changes of thyroid and adrenocortical functions after bone marrow transplantation with MAC conditioning regimen in leukemia patients].

OBJECTIVE: To investigate the effect of MAC conditioning regimen on endocrine glands function in leukemia patients after bone marrow transplantation(BMT). METHODS: Thyroid and adrenocortical functions were assayed by radioimmunoassay (RIA) in 26 leukemia patients before and after BMT. RESULTS: All patients had normal thyroid and adrenocortical functions before BMT. As compared with that pre BMT, the median serum TSH levels were increased at 1, 3 and 6 months post BMT(P < 0.01). This thyroid dysfunctions were found in 7 of 26 patients, 6 of whom were recovered at 6 months post BMT. CONCLUSION: There was little effect of MAC conditioning regimen on adrenocortical function. Thyroid dysfunctions were found in 28% of the patients after BMT, and normalized in a short period without replacement therapy.

Adolescent↗

PubMed1998

[Solid adsorption and stability of essential oil from pericarp of Gaultheria yunnaensis (Franch.) Rehd].

Experiments have been made on the solid adsorption and stability of the essential oil extracted from Gaultheria yunnanensis. The results show that among the chemical constituents of the oil, methyl salicylate accounts for 99.66%. Grain adsorbents of aluminum hydroxide gel have been proved useful in obtaining higher release rates of the oil at required temperatures as well as keeping the oil stable at room temperature.

Adsorption↗

PubMed1998

Evaluation of left ventricular function with cine magnetic resonance four chamber/multiple slice multiple phase sequence.

OBJECTIVE: To investigate the value of cine magnetic resonance(MR) in determination of cardiac function by using four chamber/multiple slice multiple phase (4CH/MSMP) sequence. METHODS: In 18 healthy subjects, several indices of left ventricular function were measured by using cine MR 4CH/MSMP sequence, and the correlation of the results was compared with ultrasound cardiography by t test. RESULTS: In the measurement of left ventricular short diameter, left ventricular posterior wall thickness, internal ventricular septum thickness, left ventricular end diastolic and end systolic volume, the values of cine MR 4CH/MSMP sequence correlated well with those of echocardiography. The gamma value was between 0.88 and 0.99. CONCLUSION: The cine MR 4CH/MSMP sequence may be considered an important noninvasive modality for accurate assessment of cardiac function.

Adult↗

PubMed1998

[GABA mediated inhibitory effect of amygdala on the activity of medial geniculate body neurons].

On 10 New Zealand white rabbits immobilized with Flaxedil, the inhibitory effect of amygdaloid stimulation on the responses of medial geniculate body (MGB) neurons to tone bursts and the involved neurotransmitter mechanism were investigated with microiontophoresis technique. The results showed that application of GABA could cause a suppression of spontaneous activity of MGB neurons while GABAA antagonist bicuculline had an opposite effect. Iontophoretic injection of GABA gave an inhibitory effect on MGB neurons similar to that caused by stimulating the amygdala or the auditory cortex behind the rhinal sulcus (ACBRS), and in particular, the GABA induced suppression could be completely antagonized by application of bicuculline. Taken together, these data suggested that GABA mediated the amygdaloid inhibitory effect. It seemed unlikely that glycine was involved in the effect, since strychnine, a glycine antagonist, could not affect the descending inhibition from ACBRS area.

Amygdala↗

PubMed1998

[The relationship between chromatographic retention value and grey model parameters].

The relationship between development parameter a, grey action variable u in the grey model GM(1,1) and parameters A,B which express the relation of k' and phi, that is, 1nk' = A + B phi have been studied. The functions of these two kinds of parameters which are a = -B lambda and u = B lambda eA[(1 - e-B lambda)(-1) - 1] are given. Therefore, it can predict the position of peaks and the possibility of separating the components in different mixtures. It verifies the experimental data, and gives out a proper method to amend equations. The results show that the function is fit for not only the research of chromatographic parameters of explosives but also the prediction of A,B values of other compounds.

Chromatography↗

PubMed1998

[Determination of HIgG in Human plasma by high performance membrane affinity chromatography(HPMAC)].

An assay technique for determination of Human IgG in human plasma has been developed by utilizing Protein A bound to the modified cellulose matrices based on the strong affinity between protein A and Fc region of IgG. The pH values of loading buffer and elution buffer were 7.0 and 2.3 respectively. The cartridge used was 20 mm x 4 mm i.d. and detection was carried out with a UV monitor at 280 nm. The non-specific adsorption of two kinds of media has been studied. The media without hexyldiamine arm gives very low non-specific adsorption BSA. The calibration curve showed a good linearity (correlation coefficient > 0.9992) in the injected amount range of 9-70 micrograms for HIgG. The total time for separation and determination was within 5 min and the total time of rapid assay was within 30 s. Relative standard deviations of peak areas were 1.5% (n = 5) and 3.6% (n = 3) for HIgG in standard solution and human plasma respectively.

Chromatography, Affinity↗