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Biomedical subjects

G H Chen

Publications and source records attributed to G H Chen.

At least 19 recordsLinked to original sources
PubMed2002

Density matrix negativity for two oscillators in an Agarwal bath.

A system of two harmonic oscillators is placed in an Agarwal bath. The resulting quantum master equations are studied with the help of quantum characteristic functions. The density matrix positivity is investigated in view of the recent interest in searching for a sound quantum dissipation theory. An analytical criterion is derived for density matrix negativity for two uncoupled oscillators. It is found that, for an initial two-oscillator squeezed state with a real squeezing parameter s, density matrix negativity occurs for two uncoupled oscillators at temperatures lower than Planck's over 2 pi omega/(k(B) ln coth/s/) with omega the oscillator frequency and k(B) the Boltzmann factor. As a by-product an analytical expression is also obtained for determining the quantum separability of two uncoupled oscillators. The effects of interoscillator coupling on density matrix negativity are discussed.

Journal Article↗
PubMed2002

Primary resistance to antibiotics and its clinical impact on the efficacy of Helicobacter pylori lansoprazole-based triple therapies.

AIM: To evaluate Helicobacter pylori primary resistance and its clinical impact on the efficacy of two lansoprazole-based eradication triple therapies. METHODS: H. pylori-positive patients (n=228) were randomized to receive one of the 1-week regimens: lansoprazole 30 mg, clarithromycin 500 mg and amoxicillin 1 g (LAC), or lansoprazole 30 mg, clarithromycin 500 mg and metronidazole 500 mg (LMC), each given twice daily. H. pylori status was assessed by 13C-urea breath test and culture at diagnosis and by 13C-urea breath test 6 weeks after therapy. Antibiotic susceptibility was determined by E-test (n=98). RESULTS: The eradication rates with per protocol/ intention-to-treat analyses were: LAC (n=95/114) 83%/69% and LMC (n=96/114) 85%/72%. Primary resistance was 11% for clarithromycin, 41% for metronidazole and 0% for amoxicillin. Eradication in metronidazole-susceptible/-resistant strains was 85%/82% in LAC and 83%/63% in LMC. Significantly lower cure rates were observed in clarithromycin-resistant patients treated with LAC (95% vs. 0%, P < 0.001) and LMC (86% vs. 0%, P < 0.001). CONCLUSIONS: One-week LAC and LMC are similarly effective therapies. Clarithromycin resistance significantly affected H. pylori eradication in both regimens.

2-Pyridinylmethylsulfinylbenzimidazoles↗
PubMed2001

Salinity effect on mechanical dewatering of sludge with and without chemical conditioning.

The salinity levels of wastewater and sludge are relatively high in some coastal cities as they may use saline water for toilet flushing, and as such,the sludge dewaterability can be affected by it. The salinity effect on sludge dewaterability was therefore investigated through experimental testing of specific resistance in filtration (SRF), time to filter (TTF), and final solid content of sludge. SRF and TTF were determined using Buchner funnel tests. The final solid content was estimated by centrifuging the sludge at four levels of rotational speed. Sludge with three salinity levels (5,000, 10,000 and 20,000 ppm) were considered in this study. Coagulants such as alum, iron(II) sulfate, and organic polyelectrolytes were added to the sludgetostudythe dewaterability of such sludge with chemical conditioning. Experimental results show that doubling the salinity level of the sludge from 10,000 to 20,000 ppm shows not much change in SRF and TTF. Compared with the sludge without chemical conditioning, the addition of the coagulants to the sludge at a salinity level of 5,000 ppm drastically reduces its SRF and TTF. However, sludge with and without chemical conditioning at a salinity of 20,000 ppm has similar SRF and TTF. The final solid content of sludge increases almost linearly with salinity. Among the coagulants used in this study, the cationic polyelectrolyte is found to be better in improving sludge dewaterability, while iron(II) sulfate performs slightly better in enhancing the final solid content of the sludge.

Particle Size↗
PubMed2001

[Analysis of amino acids and vitamins in ginkgo biloba leaves].

The contents of amino acids and 10 kinds of vitamins in ginkgo biloba leaves were analyzed via HPLC. The results shows that it contains 92.26 mg amino acids per gram leaves the rate of essential amino acids amount to total amino acids amount is 46.9% and the contents of Vc, Vpp, VE, VB6, PGA is 81.47 mg, 9.43 mg, 4.09 mg, 2.90 mg, 1.69 mg per gram leaves respectively. The present effective data will be helpful for further research in its chemical composition and comprehensive utilization.

Amino Acids↗
PubMed2001

High-level production of recombinant chicken cystatin by Pichia pastoris and its application in mackerel surimi.

A high level of the secreted form of recombinant chicken cystatin was expressed in Pichia pastoris X-33 by chromosomal integration of multiple copies of an expression cassette containing chicken cystatin under the control of glyceraldehyde-3-phosphate dehydrogenase promoter. The inhibition ability of the recombinant for papain-like proteinase was found to correspond to those of natural chicken cystatin. The recombinant cystatin substantially inhibited the proteolysis of myosin and gel softening, which consequently improved the gel properties of mackerel surimi.

Animals↗
PubMed2001

Expression of soluble form carp (Cyprinus carpio) ovarian cystatin in Escherichia coli and its purification.

A DNA encoding thioredoxin-mature carp ovarian cystatin (trx-cystatin) fusion protein was ligated into a pET-23a(+) expression vector and then transformed into Escherichia coli AD494(DE3) expression host. After induction by isopropyl beta-D-thiogalactopyranoside, a high level of the soluble form of recombinant trx-cystatin was expressed in the cytoplasm of E. coli. The recombinant trx-cystatin could be purified by Ni(2+)-NTA agarose affinity chromatography. The molecular mass (M) of the recombinant trx-cystatin was approximately 28 kDa composed of recombinant thioredoxin (16 kDa) and recombinant mature carp ovarian cystatin (12 kDa). Both recombinant trx-fused and mature carp ovarian cystatins were stable at pH 6-11. No obvious decrease in activity was observed even after 5 min of incubation at 60 degrees C. They exhibited papain-like protease inhibition activity comparable to that of the mature carp ovarian cystatin, which could inhibit papain and mackerel cathepsins L and L-like, but not cathepsin B.

Animals↗
PubMed2001

The effect of jejunal meal feeding on gastroesophageal reflux.

BACKGROUND: Postprandial gastric distention is frequently associated with transient lower esophageal sphincter relaxation and gastroesophageal reflux (GER). Since the role of nutrient perfusion into the jejunum in inducing GER is not well understood, we studied the effect of jejunal feeding on GER through a percutaneous gastrojejunal tube in patients with and without reflux esophagitis. METHODS: Nine stroke patients with reflux esophagitis were fed through a percutaneous gastrojejunal tube with either a liquid meal (2 kcal/2 ml/min) or saline for 2 h randomly on 2 separate days. An esophageal pH probe was placed 5 cm above the gastroesophageal junction to detect acid reflux. Six stroke patients without esophagitis were enrolled as controls. RESULTS: In both the patients with esophagitis and the controls, esophageal acid exposure (15.3% (4.9%-28.2%) versus 2.7% (0.0%-10.8%), P=0.003; 5.9% (0.5%-6.7%) versus 0.0% (0.0%-1.5%), P = 0.01) and events of acid reflux (5 (1-16) versus 2 (0-8), P = 0.02; 12 (3-17) versus 1 (0-4), P = 0.02) were significantly greater during jejunal meal feeding than during saline infusion. Furthermore, in the reflux patients, but not in the controls, acid clearance time was also greater during jejunal meal feeding than during saline infusion (2.9 min (0.5-9.6 min) versus 0.7 min (0.0-4.3 min), P = 0.04). CONCLUSIONS: We therefore conclude that jejunal nutrient infusion without gastric distention can induce GER in both patients with reflux esophagitis and controls. This implies that GER induced by jejununal nutrients may in part explain the incapability of jejunal tube feeding to prevent gastropulmonary aspiration in patients at risk.

Aged↗
PubMed2001

Small intestinal bacterial overgrowth versus antimicrobial capacity in patients with spontaneous bacterial peritonitis.

BACKGROUND: Spontaneous bacterial peritonitis (SBP) is a serious infection in cirrhotic patients with ascites. Both defects in the host defense mechanisms and the enhancement of the offensive factor (small intestinal bacterial overgrowth (SIBO)) may contribute to the development of SBP. Therefore, the aim of this study was to evaluate the role of SIBO versus various antimicrobial capacities in the pathogenesis of SBP in cirrhotic patients. METHODS: Forty-five cirrhotic patients were enrolled in this study. Bacterial overgrowth was evaluated by breath hydrogen test (BH2T). The hepatic reticuloendothelial system phagocytic index (HRESPI) was measured by intravenously injected colloid suspensions. RESULTS: The Child-Pugh scores in the SBP group were higher than in the non-SBP group (10.5 +/- 2.0 versus 8.0 +/- 1.8, P < 0.01). The ascitic protein concentration was significantly lower in the SBP group than in the non-SBP group (897 +/- 425 mg/l versus 1,325 +/- 453 mg/l, P < 0.01). Furthermore, the serum C3 concentration was lower in the SBP group than in the non-SBP group (43.1 +/- 13.6 ng/dl versus 73.2 +/- 26.4 ng/dl, P < 0.01). The serum C4 concentration was also lower in the SBP group than in the non-SBP group (12.4 +/- 4.0 ng/dl versus 16.9 +/- 6.6 ng/dl, P < 0.05). The incidence of SIBO was higher in the SBP group than in the non-SBP group (68.2% versus 17.4%, P < 0.01). HRESPI values were significantly higher in the two groups of cirrhotic patients than in the normal reference. However, there were no statistical differences in HRESPI between the two groups (8.4 +/- 2.8 min in the SBP group versus 7.9 +/- 2.8 min in the non-SBP group). CONCLUSIONS: The results of this study showed that the hepatic reticuloendothelial function is impaired in cirrhotic patients, but the degree of impairment does not differ between patients with and without previous history of SBP. Lower ascitic total protein, lower serum C3 and C4 concentrations, and presence of SIBO are all risk factors for SBP. Based on the results of our study, defects in the host defense mechanisms and the enhancement of the offensive factor (SIBO) may act in concert for the development of SBP.

Ascitic Fluid↗
PubMed2001

Efficacy of endoscopic isotonic saline-epinephrine injection for the management of active Mallory-Weiss tears.

Therapeutic endoscopy with isotonic saline-epinephrine (ISE) injection is a convenient and widely used procedure for hemostasis in upper gastrointestinal bleeding. We retrospectively evaluated 36 patients (from January 1996 to April 1999) who had been diagnosed with recent or active bleeding due to Mallory-Weiss tears in emergency endoscopic examination. The endoscopic hemostatic method with ISE injection was performed in 15 of 36 patients. The other 21 patients received conservative treatment with hemodynamic support. Patient's clinical data, laboratory data, transfusion requirements, endoscopic findings, and length of hospital stays were evaluated. Initial hemoglobin was significantly lower in the ISE group than the conservative treatment group (9.74 +/- 2.86 g/dL vs. 12.57 +/- 2.80 g/dL, respectively; p < 0.01). Mean transfusion requirements were significantly higher in the ISE group than the conservative treatment group (7.26 +/- 8.78 units vs. 2.85 +/- 6.21 units, respectively; p < 0.1). Patients in the ISE group were supposed to be having a more severe bleeding episode. Most patients achieved initial hemostasis in the ISE group and the conservative treatment group (93% and 95%, respectively). The rebleeding rate was also similar in both groups (1 in 15 in the ISE group and I in 21 in the conservative treatment group). There was no significant difference in length of hospital stay and rebleeding between these two groups (3.47 +/- 1.92 days vs. 2.47 +/- 1.47 days, respectively: p = 0.89). The endoscopic ISE injection is an inexpensive, simple, convenient therapeutic method and it can achieve initial hemostasis for active Mallory-Weiss tears.

Adult↗
PubMed2001

The correlation of depression and gastric dysrhythmia in functional dyspepsia.

Psychologic factors in functional dyspepsia have been discussed in many previous articles. However, the relationship between depression and functional dyspepsia is still obscure. We investigated the impact of depression on clinical symptoms and gastric dysrhythmia in functional dyspepsia. Thirty-nine patients with functional dyspepsia and 18 healthy subjects were included. Patients were investigated with clinical symptoms assessment, Zung's self-rating depression scale, and electrogastrography. Patients with functional dyspepsia were divided into two groups: 21 patients with depression and 18 patients without depression. The depressed patients had similar total gastrointestinal symptom severity scores compared with the nondepressed patients, but with higher total symptom frequency scores (p < 0.05). With regards to symptoms, the depressed patients had higher abdominal fullness severity and frequency scores and nausea frequency scores. The patients with functional dyspepsia had a lower percentage of normal slow wave in both the fasting and fed states and a higher percentage of bradygastria in the fasting state and tachygastria in the postprandial state (p < 0.05). There was no significant difference in the percentage of bradygastria or tachygastria between the depressed and nondepressed patients. There was no correlation between the specific type of electrogastrographic abnormality and the presence or absence of depression in functional dyspepsia patients.

Adult↗
PubMed2001

Alveolar macrophage deactivation in murine septic peritonitis: role of interleukin 10.

Sepsis predisposes the host to a number of infectious sequelae, particularly the development of nosocomial pneumonia. Mechanisms by which sepsis results in impairment of lung antibacterial host defense have not been well defined. Alveolar macrophages (AM) represent important immune effector cells of the lung airspace. In this study, we examined the effects of cecal ligation and puncture (CLP) on murine AM function ex vivo, including the expression of proinflammatory cytokines and AM phagocytic activity. AM were harvested from mice subjected to a sham operation and CLP 24 h after laparotomy, adherence purified, and challenged with lipopolysaccharide (LPS) or left unstimulated. Both unstimulated and LPS-stimulated AM from mice subjected to CLP (CLP mice) produced significantly smaller amounts of proinflammatory cytokines tumor necrosis factor alpha and interleukin (IL-12) and C-X-C chemokines KC and macrophage inflammatory protein 2 than similarly treated AM from animals subjected to a sham operation. Furthermore, AM isolated from CLP mice displayed a marked impairment in phagocytic activity, as determined by flow cytometry, with this defect persisting to 48 h post-CLP. Induction of peritoneal sepsis syndrome resulted in a time-dependent increase in IL-10 in plasma and peritoneal fluid. Interestingly, the impairment in AM proinflammatory-cytokine production and phagocytic activity observed in AM from CLP mice was partially reversed by the in vivo neutralization of IL-10 prior to AM harvest. These observations suggest that abdominal sepsis syndrome results in significant impairment in AM effector cell function, which is mediated, in part, by sepsis-induced expression of IL-10.

Animals↗
PubMed2001

Selective inhibition of COX-2 improves early survival in murine endotoxemia but not in bacterial peritonitis.

Prostaglandins of the E series are believed to act as important mediators of several pathophysiological events that occur in sepsis. Studies were performed to evaluate the effect of cyclooxygenase (COX)-2-specific inhibition on the outcome in murine endotoxemia and cecal ligation and puncture (CLP). We observed a significant time-dependent upregulation of PGE(2) production in both blood and lung homogenates of mice administered lipopolysaccharide intraperitoneally, which was nearly completely suppressed by the administration of the COX-2 inhibitor NS-398. Treatment with NS-398 significantly improved early but not late survival in lipopolysaccharide-challenged mice. On the contrary, elevated PGE(2) levels were found in bronchoalveolar lavage fluid but not in plasma of mice subjected to CLP (21 gauge). Pretreatment with NS-398 failed to significantly improve survival in CLP mice. No significant differences were noted in plasma or lung homogenate proinflammatory cytokine levels or lung neutrophil sequestration between the NS-398-treated and control groups. These results demonstrate that selective COX-2 inhibition confers early but not long-term benefits without affecting the expression of proinflammatory cytokines or the development of lung inflammation.

Animals↗
PubMed2001

Effect of electrical stimulation on acupuncture points in diabetic patients with gastric dysrhythmia: a pilot study.

BACKGROUND/AIMS: Abnormal gastric slow-wave frequencies have been observed in diabetic gastroparesis and are associated with impaired antral motor activity. In this study, we aimed at evaluating the effect of acupuncture on gastric slow waves in diabetic patients with symptoms suggesting gastric motor dysfunction. METHODS: Fifteen patients with type II diabetes who had had dyspeptic symptoms for more than 3 months were enrolled. Two acupuncture needles were inserted into the subjects' legs at the Zusanli points, and electrical stimulation (2-Hz pulses) was delivered for 30 min. Cutaneous electrogastrography was performed for 30 min at baseline, for 30 min during acupuncture, and for an additional 30 min after acupuncture. Serum gastrin, motilin, and human pancreatic polypeptide levels were also measured. RESULTS: There was a significant increase in the percentages of normal frequency during and after acupuncture (baseline vs. acupuncture and after acupuncture 21.99 +/- 19.38% vs. 45.93 +/- 19.72 and 48.92 +/- 19.56%; p < 0.01). In addition, the percentage of tachygastric frequency was decreased significantly during and after acupuncture. The dominant frequency was also changed significantly. There was an increase of serum human pancreatic polypeptide during acupuncture (baseline vs. acupuncture 56.96 +/- 27.64 vs. 73.11 +/- 22.37 pmol/l; p < 0.05). CONCLUSIONS: The results of this study revealed that electrical stimulation at the Zusanli points could increase the percentage of normal electrogastrography frequency and decrease the percentage of tachygastric frequency in diabetic patients. The data indicate that acupuncture may enhance the regularity of gastric myoelectrical activity in diabetic patients.

Acupuncture Points↗
PubMed2001

Unilateral concurrence of pyelocaliceal diverticula and intracapsular angiomyolipoma in the kidney of a cat.

A 7-month-old cat was examined for progressive abdominal distension. Radiography showed a fluid-containing cyst, which had subsequently ruptured as the result of a fall. Nephrectomy was performed, and examination revealed the coexistence of pyelocaliceal diverticula with a cystic intracapsular angiomyolipoma (mesenchymal hamartoma) in the left kidney. The diverticula were present on both cranial and caudal poles of the kidney and were lined by transitional epithelium. The hamartoma was characterized by the presence of multiple mesenchymal tissues, including thick-walled blood vessels, smooth muscle, and adipose tissue.

Angiomyolipoma↗
PubMed2001

Sepsis-induced immunosuppression: from bad to worse.

The sepsis syndrome is characterized by the acute release of a variety of inflammatory mediators, which often result in detrimental effects to the host. The release of these mediators is regulated and counterbalanced by the coordinated expression of antiinflammatory molecules. It is the balance between the expression of pro- and antiinflammatory mediators that often determines the magnitude of early tissue injury and subsequent risk of infectious complications. As our understanding of the pathophysiology of sepsis continues to evolve, we have gained a greater appreciation for the effects that sepsis and similar states of overwhelming stress have on host antimicrobial immunity. A number of functional defects in leukocytes isolated from sepsis patients have been characterized. These defects include diminished expression of important cell surface antigens, dysregulated cytokine production, alterations in antigen-presenting ability, and accelerated apoptosis. Impaired leukocyte function has important clinical ramifications, as high mortality rates have been observed in patients displaying evidence of sepsis-induced immune deactivation. In this article, we review the current literature supporting evidence of dysregulation of host immunity occurring during sepsis syndrome, characterize the underlying pathophysiology, and describe novel therapeutic interventions directed at augmenting host immunity during sepsis.

Adjuvants, Immunologic↗
PubMed2001

Hemolysis, elevated liver enzymes, and low platelet count (HELLP) syndrome with acute cortical blindness.

The coincidence of hemolysis, elevated liver enzymes, and low platelet count (HELLP) syndrome and cortical blindness is an uncommon but very dramatic event. We describe a case of HELLP syndrome complicating with acute cortical blindness before delivery. A 27 year-old woman, gravida 1, para 0, with normal medical history, was referred to our emergency department at the 33th week of gestation due to headache, vomiting, and blurred vision. The ophthalmologic examination showed intact pupillary light reflexes and normal ophthalmoscopic findings, but no light perception in either eye. Brain computed tomography showed normal findings. HELLP syndrome and preeclampsia was diagnosed based on the findings of hypertension and proteinuria as well as laboratory data. Prompt delivery was performed in order to achieve good maternal and neonatal outcomes.

Acute Disease↗