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Biomedical subjects

G Xu

Publications and source records attributed to G Xu.

At least 163 records · Page 9Linked to original sources
PubMed2000

Treatment of urinary calculi with ureteroscopy and Swiss lithoclast pneumatic lithotripter: report of 150 cases.

PURPOSE: To present our clinic experience with the Swiss Lithoclast pneumatic lithotripter in the endoscopic management of urinary calculi. PATIENTS AND METHODS: From August 1994 to December 1997, 145 patients with ureteral calculi and 5 patients with urethral calculi were treated with the Swiss Lithoclast. RESULTS: In the ureteral stone group, ureteroscopic addressing of the stones was successful in 133 patients. In 27 patients, the stones were partially fragmented and remained in situ or were pushed back to the calices. They were subsequently treated successfully with SWL. Stones were fragmented in a single session in 101 cases. Complications associated with the procedure included five perforations and four urinary tract infections. All of the five urethral stone patients were treated successfully with pneumatic lithotripsy. The overall successful fragmentation rate thus was 70.7% (106 of 150) and 88.7% (133 of 150) in combination with adjuvant SWL. CONCLUSIONS: We have found Swiss Lithoclast pneumatic lithotripsy to be a safe, effective, and economical treatment method for urinary calculi. If combined with other modalities such as SWL, this treatment will be even more effective.

Adolescent↗
PubMed2000

Immunohistochemical studies on vascular endothelial growth factor and platelet endothelial cell adhesion molecule-1/CD-31 in islet transplantation.

Neovascularization may be necessary for better and longer function of transplanted islets. Vascular endothelial growth factor (VEGF) is known to be one of the most important factors of angiogenesis. Recently, VEGF was reported to be expressed in islets of normal pancreas. We studied the expression of VEGF and neovascularization related peptides in transplanted islets. To determine the angiogenic microcapillary, immunochemical staining was performed for Factor VIII-related antigen (von Willebrand factor [vWF]) and platelet endothelial cell adhesion molecule-1/CD31 (PECAM-1), both of which are known as markers of the angiogenic microvessel. Transplantable islets were isolated from Lewis rats (8-10 weeks of age) by discontinuous dextran gradient after collagenase digestion. Seven to twelve hundred islets were injected into the portal vein (IPV group, n = 7) or transplanted into subnephrocapsular cavity (SNC, n = 12) of the same descent rats. In the IPV group, the liver was resected 1 hour, 1 week, or 4 weeks after transplantation (Tx). In the SNC group, the kidney was resected 1, 3, 7, or 28 days after Tx. Each tissue was fixed in formaldehyde and embedded in paraffin. Serial 4-microm slices were immunostained for insulin, VEGF, PECAM-1, or vWF using specific antibodies. In IPV group, insulin-positive cells were VEGF positive as were in the normal pancreas at all time points. Islets of 1 hour after Tx were barely PECAM-1 positive as were in normal pancreas, but islets became weakly stained at 7 and 28 days after Tx. In vWF staining, transplanted islets showed stronger staining than those in the normal pancreas. In SNC group, VEGF was also stained in insulin-positive cells at 1, 3, 7, and 28 days. In PECAM-1 staining, islets of 1 day after Tx were barely stained as were in normal pancreas. However, the staining was increasingly enhanced from 3 to 7 days and then appeared weakened at 28 days after Tx. In vWF staining, islets were always vWF positive, as was seen in IPV group. This study revealed that PECAM-1 appeared in islets after islet Tx, suggesting that neovascularization occurs within the islet grafts. On the other hand, VEGF of transplanted islet did not obviously vary with time. Enhancement of the neovascularization may lead to better results of islet Tx.

Animals↗
PubMed2000

Expression and canalicular localization of two isoforms of the ClC-3 chloride channel from rat hepatocytes.

The molecular identities of functional chloride channels in hepatocytes are largely unknown. We examined the ClC-3 chloride channel in rat hepatocytes and found that mRNA for two different isoforms is present. A short form is identical to the previously reported sequence for rat ClC-3, and a long form contains a 176-bp insertion immediately upstream of the translation initiation site. This predicts a 58-amino acid NH(2) terminal insertion. Both long and short form mRNA was expressed in diverse tissues of the rat. Transient transfection of the long form in CHO-K1 cells resulted in currents with an I(-) > B(-) > Cl(-) selectivity sequence, outward rectification, and inactivation at positive voltages. Short form currents had identical ionic selectivity but displayed a more extreme outward rectification and showed no voltage-dependent inactivation. Immunofluorescence and immunoblots localized native ClC-3 preferentially but not exclusively to the canalicular membrane. We have therefore identified a new isoform of rat ClC-3 and shown that expression of both isoforms produces functional channels. In hepatocytes, ClC-3 is located in association with the canalicular membrane.

Animals↗
PubMed2000

Differences in the preparation and practice of male and female physicians from combined baccalaureate--MD degree programs.

OBJECTIVE: To account for age and premedical education in determining whether or not men and women medical school graduates differ significantly in opinions of their medical school preparation, in professional activities, and in personal qualities and values. METHODS: 727 graduates (1983-1987) of seven combined baccalaureate-MD degree programs were surveyed. Men's and women's responses were compared. RESULTS: Women graduates were more likely than men to work less than full time and to report less preparation in the basic sciences, less scholarly activity, and more concern about psychosocial issues. CONCLUSION: Differences between men and women graduates have persisted despite women's increased access to medical school. Even a special curriculum does not moderate these differences. We call on academic medicine to value humanism in health care, not just economics.

Analysis of Variance↗
PubMed2000

Ileal bile acid transport regulates bile acid pool, synthesis, and plasma cholesterol levels differently in cholesterol-fed rats and rabbits.

We investigated the effect of ileal bile acid transport on the regulation of classic and alternative bile acid synthesis in cholesterol-fed rats and rabbits. Bile acid pool sizes, fecal bile acid outputs (synthesis rates), and the activities of cholesterol 7alpha-hydroxylase (classic bile acid synthesis) and cholesterol 27-hydroxylase (alternative bile acid synthesis) were related to ileal bile acid transporter expression (ileal apical sodium-dependent bile acid transporter, ASBT). Plasma cholesterol levels rose 2.1-times in rats (98 +/- 19 mg/dl) and 31-times (986 +/- 188 mg/dl) in rabbits. The bile acid pool size remained constant (55 +/- 17 mg vs. 61 +/- 18 mg) in rats but doubled (254 +/- 46 to 533 +/- 53 mg) in rabbits. ASBT protein expression did not change in rats but rose 31% (P < 0.05) in rabbits. Fecal bile acid outputs that reflected bile acid synthesis increased 2- and 2.4-times (P < 0.05) in cholesterol-fed rats and rabbits, respectively. Cholesterol 7alpha-hydroxylase activity rose 33% (24 +/- 2.4 vs. 18 +/- 1.6 pmol/mg/min, P < 0.01) and mRNA levels increased 50% (P < 0.01) in rats but decreased 68% and 79%, respectively, in cholesterol-fed rabbits. Cholesterol 27-hydroxylase activity remained unchanged in rats but rose 62% (P < 0.05) in rabbits. Classic bile acid synthesis (cholesterol 7alpha-hydroxylase) was inhibited in rabbits because an enlarged bile acid pool developed from enhanced ileal bile acid transport. In contrast, in rats, cholesterol 7alpha-hydroxylase was stimulated but the bile acid pool did not enlarge because ASBT did not change. Therefore, although bile acid synthesis was increased via different pathways in rats and rabbits, enhanced ileal bile acid transport was critical for enlarging the bile acid pool size that exerted feedback regulation on cholesterol 7alpha-hydroxylase in rabbits.

Animals↗
PubMed2000

Regulation of 25- and 27-hydroxylation side chain cleavage pathways for cholic acid biosynthesis in humans, rabbits, and mice. Assay of enzyme activities by high-resolution gas chromatography;-mass spectrometry.

In classic cholic acid biosynthesis, a series of ring modifications of cholesterol precede side chain cleavage and yield 5beta-cholestane-3alpha, 7alpha, 12alpha-triol. Side chain reactions of the triol then proceed either by the mitochondrial 27-hydroxylation pathway or by the microsomal 25-hydroxylation pathway. We have developed specific and precise assay methods to measure the activities of key enzymes in both pathways, 5beta-cholestane-3alpha, 7alpha, 12alpha-triol 25- and 27-hydroxylases and 5beta-cholestane-3alpha, 7alpha, 12alpha, 25-tetrol 23R-, 24R-, 24S- and 27-hydroxylases. The extracts from either the mitochondrial or microsomal incubation mixtures were purified by means of a disposable silica cartridge column, derivatized into trimethylsilyl ethers, and quantified by gas chromatography;-mass spectrometry with selected-ion monitoring in a high resolution mode. Compared with the addition of substrates in acetone, those in 2-hydroxypropyl-beta-cyclodextrin increased mitochondrial triol 27-hydroxylase activity 132% but decreased activities of the enzymes in microsomal 25-hydroxylation pathway (triol 25-hydroxylase and 5beta-cholestane-3alpha, 7alpha, 12alpha, 25-tetrol 23R-, 24R-, 24S- and 27-hydroxylases) 13;-60% in human liver. The enzyme activities in both pathways were generally 2- to 4-times higher in mouse and rabbit livers compared with human liver. In all species, microsomal triol 25-hydroxylase activities were 4- to 11-times larger than mitochondrial triol 27-hydroxylase activities but the activities of tetrol 24S-hydroxylase were similar to triol 27-hydroxylase activities in our assay conditions. The regulation of both pathways in rabbit liver was studied after bile acid synthesis was perturbed. Cholesterol feeding up-regulated enzyme activities involved in both 25- (64;-142%) and 27- (77%) hydroxylation pathways, while bile drainage up-regulated only the enzymes in the 25-hydroxylation pathway (178;-371%). Using these new assays, we demonstrated that the 25- and 27-hydroxylation pathways for cholic acid biosynthesis are more active in mouse and rabbit than human livers and are separately regulated in rabbit liver.

Animals↗
PubMed2000

Urethroscopic realignment of ruptured bulbar urethra.

PURPOSE: We evaluated the efficiency of early endoscopic realignment as primary therapy for bulbar urethral disruption after straddle injury. MATERIALS AND METHODS: From 1990 to 1999 we treated 16 men who had bulbar urethral disruption with endoscopic realignment. Followup included uroflowmetry and urethroscopy at 39 to 85 months. RESULTS: All 16 cases were successfully treated at a single session without intraoperative or postoperative complications. Only 2 patients required intermittent self-dilation once weekly and all were potent during followup. CONCLUSIONS: The results of this minimally invasive procedure are comparable to those of open surgery. It may be performed on an outpatient basis using only local anesthesia. Our results imply that this cost-effective therapy should be done as the initial step in most patients with bulbar urethral disruption.

Adolescent↗
PubMed2000

Hyperabsorption and retention of campestanol in a sitosterolemic homozygote: comparison with her mother and three control subjects.

We measured the percent absorption, turnover, and distribution of campestanol (24-methyl-5alpha-cholestan-3beta-ol) in a sitosterolemic homozygote, her obligate heterozygous mother, and three healthy human control subjects. For reasons relating to sterol hyperabsorption, the homozygote consumed a diet low in plant sterols that contained campestanol at about 2 mg/day. The heterozygote and three control subjects were fed a diet supplemented with a spread that contained campestanol at 540 mg/day and sitostanol (24-ethyl-5alpha-cholestan-3beta-ol) at 1.9 g/day as fatty acid esters. Plasma campestanol concentrations determined by capillary gas-liquid chromatography were 0.72 +/- 0.03 mg/dl in the homozygote, 0.09 +/- 0.04 mg/dl in the heterozygote, and 0.05 +/- 0.03 mg/dl for the control mean. After simultaneous pulse labeling with [3alpha-(3)H]campestanol intravenously and [23-(14)C]campestanol orally, the maximum percent absorption measured by the plasma dual-isotope ratio method as a single time point was 80% in the homozygote, 14.3% in the heterozygote, and 5.5 +/- 4.3% as the mean for three control subjects. Turnover (pool size) values estimated by mathematical analysis of the specific activity versus time [3alpha-(3)H]campestanol decay curves were as follows: 261 mg in the homozygote, 27.3 mg in the heterozygote, and 12.8 +/- 7.6 mg in the three control subjects (homogygote vs. controls, P < 0.001). The calculated production rate (mg/24 h) equivalent to actual absorption in the presence of dietary sterols and stanols was 0.67 mg/day or 31% of intake in the homozygote, 2.1 mg/day or 0.3% of intake in the heterozygote, and 0.7 +/- 0.3 mg/day or 0.1% of intake in the three control subjects. However, the excretion constant from pool A (K(A)) was prolonged markedly in the homozygote, but was 100 times more rapid in the heterozygote and three control subjects.Thus, campestanol, like other noncholesterol sterols, is hyperabsorbed and retained in sitosterolemic homozygotes. However, campestanol absorption was only slightly increased in the sitosterolemic heterozygote and removal was as rapid as in control subjects.

Adolescent↗
PubMed2000

[3-D motion detection system of human hand].

This paper presents a 3-D motion detection system of human hand, which is based on ordinary video cameras. It includes two pickup cameras, calibration frame and landmark identification system. The DLT algorithm is used to reconstruct the 3-D motion trajectory of human hand. The paper also presents the principle of the system and some detection experiments, and the results showed the good performance of the system. It offers a useful tool for the human hand motion quality analysis and evaluation.

Adult↗
PubMed2000

Changes in coagulation and tissue plasminogen activator after the treatment of cerebral infarction with lumbrokinase.

This paper aimed to investigate the effect of lumbrokinase on the anticoagulation and fibrinolysis in treating cerebral infarction. Lumbrokinase was used in patients with cerebral infarction. Patients were randomly divided into treatment group (n = 31) and control group (n = 20). Single blind method was used in this investigation. The Chinese stroke score was used to evaluate the results of treatment before and after administration of lumbrokinase. Kaolin partial thromboplastin time (KPTT), prothrombin time (PT), fibrinogen content, vWF content were analyzed, and tissue plasminogen activator (t-PA) activity, plasminogen activator inhibitor (PAI) activity, D-dimer level were assayed. In both groups, the stroke score decreased after administration, but in the treatment group, it was more obvious. In the treatment group, KPTT was prolonged, t-PA activity and D-dimer level increased, while the content of fibrinogen decreased significantly. There were no significant changes of PT and PAI activity in both groups. It is concluded that lumbrokinase is beneficial to the treatment of cerebral infarction. The effect of lumbrokinase is related to the inhibition of intrinsic coagulation pathway and the activation of fibrinolysis via an increase of t-PA activity.

Aged↗
PubMed2000

Adjuvant chemotherapy following radical surgery for non-small-cell lung cancer: a randomized study on 70 patients.

OBJECTIVE: To evaluate the efficacy of adjuvant chemotherapy after radical surgery for non-small-cell lung cancer (NSCLC). METHODS: Seventy patients with NSCLC (stages I-III) undergoing radical surgery were randomized into two groups. Group 1 (n = 35): combination group, which received adjuvant chemotherapy with cyclophosphamide 300 mg/m2, vincristine 1.4 mg/m2, adriamycin 50 mg/m2, and lomustine 50 mg/m2 on day 1, and cisplatin 20 mg/m2 on days 1-5. The treatment was repeated every 4-6 weeks for 4 cycles, followed by oral administration of ftorafur (FT-207) 600-900 mg/d for 1 year. Group 2 (n = 35): surgery group, which received surgical treatment only. RESULTS: The overall 5-year survival rate was 48.6% in the combination group versus 31.4% in the surgery group, and difference between the two groups was not statistically significant (chi 2 = 3.09, P > 0.05). The 5-year survival rate for patients with stage III disease was 44% and 20.8% in the combination and surgery groups, respectively, showing a statistically significant difference (chi 2 = 5.28, P < 0.025). The 5-year survival rates of patients in stages I-II in the two groups were 60.0% and 54.5%, respectively, and were not significantly different (chi 2 = 0.03, P > 0.75). CONCLUSION: Postoperative adjuvant chemotherapy provides statistically significant improvement in the 5-year survival rate only in patients with stage III NSCLC.

Adult↗
PubMed2000

[The effects of exogenous p16 gene on proliferation and apoptosis of human nasopharyngeal carcinoma cell line CNE-2].

OBJECTIVE: To study the effects of exogenous p16 gene on proliferation and apoptosis of human nasopharyngeal carcinoma cell line CNE-2. METHODS: Exogenous p16 gene was transfected into CNE-2 cells by lipofectin. After G418 selection, we obtained p16 stably expressed NPC cell clones (CNE-2-p16), and compared it with the mock-transfected clones(CNE-2-vect). Cell cycle was determined by flow cytometry, and cell apoptosis was examined by fluorescent (Hoechst) staining and TUNEL. P16 protein and p53 protein were stained immunohistochemically with relevant antibodies. RESULTS: Exogenous p16 gene was successfully expressed by CNE-2 2 cells. The growth of CNE-2-p16 cells was inhibited significantly. In CNE-2-p16 cells, cycle arrest in G1 phase, with decrease in percentage of S phase cells. Apoptotic index of CNE-2-p16 was significantly increased. CNE-2-p16 cells were positive for p53 protein that it was negative in CNE-2 cells. CONCLUSION: Exogenous p16 inhibits proliferation and induces apoptosis of human nasopharyngeal cancer CNE-2 cell line. It may be related to the up-regulation of wild type p53 gene.

Apoptosis↗
PubMed2000

[Carcinogenesis effects of gastric and duodenal refluxate on esophageal mucosa].

OBJECTIVE: To investigate the effects of different refluxant on esophageal carcinogenesis in rats. METHODS: The animal models of gastroesophageal reflux (G), duodenoesophageal reflux (D) and duodenogastroesophageal reflux (DG) and no reflux as control (C) were made by operations. The rats in all of the groups were given carcinogen (methyl-n-amyl nitrosamine, MANA). They were killed at 4, 20, 26, 40-week, then their esophagi were taken to the morphologic study and the expression of p53, cyclinD(1), CDK(4) studied with immunohistochemical studies. RESULTS: At 4-week without carcinogen, most of rats in reflux groups displayed evidence of esophageal mucosal injury. The degree of mucosal injury in D group was greater than that in DG which was greater than that in G; and became severity with the time. At 40 weeks, the incidences of papillomas in group D, DG, G were 94.7%, 95.2%, 70.5%, respectively. All of them compared to the group C (38.5%) were significant difference. Only in both D and DG group, there were 24 with esophageal columnar metaplasia, 20 with dysplasia and 11 with cancer. The overexpression of p53, CDK(4), cyclin D(1) was seen in D and DG groups, while in G group, the overexpression of p53 and cyclin D(1) were seen only. CONCLUSION: Both of gastric juice and duodenal contents reflux can promote tumourgenesis of MANA on esophagi by changing the expression of cell cycle-related protein. The effect of duodenal contents is stronger. It may play an important role in tumourgenesis of gastroesophageal reflux disease.

Animals↗
PubMed2000

[Dural arterovenous fistula involving cavernous sinus].

OBJECTIVE: To study the pathogenesis and treatment of dural arteriovenous fistulas (DAVFS) involving the cavernous sinus. METHODS: 32 cases were embolized with particle by microcatheterization via endovascular approach and ervation by digital substraction angiography. Of the 32 cases, 14 were embolized by microsoils through superior petrosal sinus approach into the cavernous sinus. RESULTS: In 28 of the 32 cases the fistulas were completely embolized angiographically. The fistulas were partly embolized in 4 of the 32 cases. The carotid artery was compressed for 6 months. One week later, the fistula disappeared angiographically. No fistulas were found during the follow-up for 6 months to 8 years. CONCLUSION: Endovascular treatment of DAVFS involving the cavernous sinus is effective.

Adolescent↗
PubMed2000

[Iodine-125 labeled monoclonal antibody 3H11: in radioimmunoguided surgery for primary gastric cancer].

OBJECTIVE: To evaluate the clinical usefulness of iodine-125 labeled monoclonal antibody (MAb) 3H11 in radioimmunoguided surgery (RIGS) for patients with gastric cancer. METHODS: Thirty-five patients with primary gastric cancer were enrolled. Via endoscopy, iodine-125 labeled MAb 3H11 was injected into submucosa around the tumor. All patients underwent surgery 4 to 11 days after administration. Intraoperative radioimmunodetection was performed using a hand-held gamma-detecting probe. The counts of target sites were obtained, and tumor-to-normal tissue (T/NT) ratios were calculated. The T/NT ratio of 3.5:1 was taken as the lowest threshold value of positive gastric wall infiltration, and 3.0:1 for lymph node metastasis. Serial sections of those RIGS-positive lymph nodes, which were originally diagnosed as negative by routine histology, were made. Immunohistochemical staining was performed to detect the existence of lymphatic micrometastasis. RESULTS: Of thirty-five patients, 33 underwent RIGS successfully. The accuracy rate in detecting tumor infiltration of the incision margins was 97.0%, and the specificity 98.5%. In the group of patients with an interval of 6 to 8 days between injection and operation (n = 25), the RIGS results were satisfying. For the detection of lymphatic metastasis, the sensitivity of RIGS was 83.6%, the specificity 95.0%, and the accuracy 91.3%. The existence of lymphatic micrometastasis were verified immunohistochemically in 52.6% (10/19) of those RIGS positive but histologically negative lymph nodes. CONCLUSION: This study validates the use of iodine-125 labeled monoclonal antibody 3H11 for the intraoperative detection of carcinomatous lesions in gastric cancer.

Adult↗
PubMed2000

[Caspase 3 in the cytokines induced acute leukemia cell apoptosis].

OBJECTIVE: To explore the variation and significance of caspase 3 activity in the process of G-CSF and GM-CSF regulated NB4 cell apoptosis. METHODS: Cell morphology, flow cytometry and DNA fragmentation assay were used to demonstrate the apoptosis induced by G-CSF and GM-CSF. Caspase 3 activity was detected by spectrofluorometry, and its inhibition test by AC-DEVD-CHO. RESULTS: G-CSF could induce NB4 cell apoptosis, while GM-CSF could not. Caspase 3 activity was significantly higher in the apoptotic cells than in control cells. The G-CSF induced NB4 cell apoptosis was efficiently inhibited by AC-DEVD-CHO. CONCLUSIONS: G-CSF and GM-CSF exert different effects on the apoptosis of leukemic cells. G-CSF induced apoptosis of leukemic cells through activation of caspase 3.

Apoptosis↗
PubMed2000

[Regulation of telomerase activity in HL-60 and NB4 cells by arsenic trioxide].

OBJECTIVE: To investigate the regulation of telomerase activity in HL-60 and NB4 cells exposed to arsenic trioxide (As(2)O(3)). METHODS: Cell morphology, intracellular DNA distribution, bcl-2 expression and telomerase activity were evaluated in HL-60 and NB4 cells exposed to As(2)O(3) or ATRA. RESULTS: The differentiation induction of HL-60 and NB4 cells by low concentration of As(2)O(3) was weaker than that by ATRA, but downregulation effect of As(2)O(3) on telomerase activity was more strong and quick. Higher concentration of As(2)O(3) induced apoptosis in HL-60 or NB4 cells accompanied by more rapid down regulation of telomerase activity and bcl-2 expression. Neither As(2)O(3) nor ATRA showed direct inhibition effect on telomerase activity. CONCLUSION: The downregulation of telomerase activity by low concentration of As(2)O(3) in HL-60 and NB4 cells is the result of overlap of differentiation and apoptosis. There are similar mechanisms in the regulation of telomerase activity and apoptosis in different leukemia cells. Bcl-2 may play an important role in these mechanisms.

Apoptosis↗