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J H Liu

Publications and source records attributed to J H Liu.

At least 73 records · Page 4Linked to original sources
PubMed2000

Highly regioselective synthesis of 3,4-disubstituted 1H-pyrrole.

A highly regioselective method for the synthesis of 3, 4-disubstituted 1H-pyrroles has been developed employing the ipso-directing property of a trimethylsilyl group. As a key starting material in this study, the known 3,4-bis(trimethylsilyl)-1H-pyrrole (3), was protected with carefully chosen groups, namely tert-butoxycarbonyl, N,N-dimethylaminosulfonyl, p-toluenesulfonyl, and triisopropylsilyl. A highly regioselective monoiodination of these 1-protected pyrroles was achieved by reaction with iodine-silver trifluoroacetate at low temperatures. Subsequent palladium-catalyzed cross-coupling reactions afforded 1-protected-4-substituted 3-trimethylsilyl-1H-pyrroles, which again underwent further room-temperature ipso-iodination and palladium-catalyzed cross-coupling reactions to provide symmetrical and unsymmetrical 1-protected-3,4-disubstituted 1H-pyrroles. Deprotection of 1-(tert-butoxycarbonyl) and 1-(N, N-dimethylaminosulfonyl) groups was found to be nontrivial. The 1-(p-toluenesulfonyl) protecting group was eventually proved to be superior to other protection groups, because it was readily removed after stepwise ipso monoiodinations and palladium-catalyzed cross-coupling reactions.

Pyrroles↗
PubMed2000

Chronic neutropenia mediated by fas ligand.

Chronic neutropenia, often associated with rheumatoid arthritis, is a characteristic finding in large granular lymphocyte (LGL) leukemia. The mechanism of neutropenia is not known. Normal neutrophil survival is regulated by the Fas-Fas ligand apoptotic system. We hypothesized that neutropenia in LGL leukemia is mediated by dysregulated expression of Fas ligand. Levels of Fas ligand in serum samples from patients with LGL leukemia were measured with a Fas ligand enzyme-linked immunosorbent assay. The effects of serum from patients with LGL leukemia on apoptosis of normal neutrophils were determined by flow cytometry and morphologic assessment. High levels of circulating Fas ligand were detected in 39 of 44 serum samples from patients with LGL leukemia. In contrast, Fas ligand was undetectable in 10 samples from healthy donors. Serum from the patients triggered apoptosis of normal neutrophils that depended partly on the Fas pathway. Resolution of neutropenia was associated with disappearance or marked reduction in Fas ligand levels in 10 of 11 treated patients. These data suggest that high levels of Fas ligand are a pathogenetic mechanism in human disease. (Blood. 2000;95:3219-3222)

Apoptosis↗
PubMed2000

Spiral CT versus MRI in neonatal airway evaluation.

Magnetic resonance imaging has become the standard means of imaging pediatric airway obstruction due to vascular anomalies. However, magnetic resonance imaging requires a long acquisition time and is prone to motion artifacts. The development of spiral or helical computed tomography provides an alternative imaging modality for evaluating pediatric airway obstruction. We present the case of a neonate with a double aortic arch which initially was not identified on magnetic resonance imaging but was visualized with spiral computed tomography. If suspicion of an intra-thoracic abnormality is high, spiral computed tomography may be a useful adjunct or replacement to magnetic resonance imaging.

Airway Obstruction↗
PubMed2000

[Effects of different loading exercises on endogenous sex hormones and their metabolites].

Small loading and strengthening exercises were performed by 22 athletes(11 males and 11 females). The levels of serum hormones and their urinary metabolites were detected. The results showed that the serum levels of testosterone(T), free testosterone(FT) and 17-OH-progesterone(17-OHP) in male athletes exhibited no conspicuous changes. The excretion of their urinary androsteroids was significantly increased after exercises(P < 0.05), but significantly decreased in the recovery period(P < 0.05). After small loading exercises, their serum levels of T and FT revealed no obvious changes except those of 17-OHP which evidently increased in female athletes(P < 0.05); whereas the excretion of their urinary steroid hormones declined promptly after the exercises and in the recovery period (all P < 0.05). After strengthening exercises, the serum levels of T, FT and 17-OHP decreased distinctly in female athletes (all P < 0.05), the excretion of their urinary steroid hormones raised clearly after training and in the recovery period(P < 0.05). Therefore, it is suggested that the secretion and metabolism of sex hormones in the organism are influenced by the loading quality of sports during training, and sexual difference exists simultaneously.

17-alpha-Hydroxyprogesterone↗
PubMed2000

Lack of mutations of BCL6 and BCL10 genes in mucosa-associated lymphoid tissue lymphomas of the orbital adnexa.

Knowledge regarding the molecular pathogenesis and progression of mucosa-associated lymphoid tissue (MALT) lymphomas of ocular adnexa is limited. Eleven cases of ocular MALT lymphoma were analyzed by clonal rearrangement of antigen receptor genes using Southern blot hybridization. Polymerase chain reaction-single stranded conformational polymorphism analysis and DNA sequencing was utilized to analyze the mutations of BCL6 and BCL10 genes. Clonal rearrangement of immunoglobulin heavy genes was found in all 11 patients. No point mutation was found in BCL6 or BCL10 genes in any of the samples analyzed. We suggest that mutations of BCL6 and BCL10 genes are rare in low-grade MALT lymphoma of ocular adnexa and are unlikely to be involved in the pathogenesis of the disease. But the role of alterations of both BCL6 and BCL10 genes in the disease progression of low-grade MALT lymphoma require additional study.

Adaptor Proteins, Signal Transducing↗
PubMed2000

IL-2 induces the association of IL-2Rbeta, lyn, and MAP kinase ERK-1 in human neutrophils.

IL-2, first identified as a T cell growth factor, has been proven to activate many cell types including polymorphonuclear neutrophils (PMN3). However, the mechanisms involved in PMN activation, especially the signaling pathways used by the IL-2R, are currently unknown. Here we demonstrate that IL-2 has the ability to induce protein tyrosine kinases in human PMN, and we provide the first evidence that lyn kinase is activated and physically associated with MAP kinase/ERK1. Co-immunoprecipitation experiments with anti-IL-2Rbeta and Western blotting with anti-p53/56lym revealed that lyn protein was present in IL-2R precipitates and that the association of lyn with IL-2Rbeta was markedly elevated by IL-2 stimulation. Furthermore the activity of lyn kinase, evaluated by an in vitro kinase assay with enolase as a substrate, increased following IL-2 stimulation. Another important finding was that, upon IL-2 activation, MAPK/ERK1 was also phosphorylated in PMN. A direct association between lyn and ERK1 was initially demonstrated by co-immunoprecipitation/Western blotting and then definitively proven by the use of a GST-ERK1 fusion protein. We showed that ERK1 binds lyn only in IL-2 stimulated PMN, but not in unstimulated PMN. These results suggest that IL-2 can promote the association of lyn protein tyrosine kinase with IL-2Rbeta as well as the direct binding of MAPK/ERK1 to lyn. The signaling pathway utilized by human PMN in response to IL-2 may thus involve the association of lyn with IL-2Rbeta and the activation process also triggers the recruitment and activation of a specific ERK.

Cells, Cultured↗
PubMed2000

Outpatient cochlear implantation in the pediatric population.

Studies have shown that the incidence of complications in pediatric cochlear implant surgery is related to the age of the child, with a higher complication rate in younger patients. Consequently, many surgeons advocate admitting these children overnight. We began our pediatric cochlear implant program starting in June 1991 using the Nucleus 22-channel cochlear implant. To date, 65 children have undergone implantation, all on an outpatient basis. To evaluate safety, complication rate, and patient satisfaction, we gave the parents of the patients a questionnaire survey to complete. All patient charts were also retrospectively reviewed. More than 90% of parents surveyed responded that they were satisfied with the outpatient treatment of their children. There were no perioperative complications or readmissions. Cochlear implantation can be safely and effectively performed on an outpatient basis without an increase in morbidity. Day surgery reduces hospital costs at least $2500.

Adolescent↗
PubMed2000

Systematic management of chyle fistula: the Southwestern experience and review of the literature.

Postoperative cervical chyle fistula after neck dissection is a complication with potentially serious morbidity. Once it is recognized, treatment decisions to optimize patient care can be difficult. Different management strategies have been advocated on the basis of institutional and personal experience. In this study we comprehensively review the published protocols and retrospectively review our experience in the management of 15 patients with chyle fistula. All patients in this study were given a trial of nonoperative management with nutritional modification, pressure dressings, and closed drainage. Medical management ultimately failed in 3 patients (20%). Two patients had prolonged courses of medical management with associated complications. An analysis of our data supports early operative intervention if the peak 24-hour drainage is greater than 1000 mL without a prompt response to medical management. Persistent low-output drainage after 10 days is associated with a prolonged management course and treatment-related complications. Optimal treatment of these patients is unclear.

Adult↗
PubMed2000

The experimental investigation of ultrasonic properties for a sonicated contrast agent and its application in biomedicine.

The ultrasonic properties of a promising ultrasound (US) contrast agent, named SDA (sonicated dextrose albumin) are reported in this paper. SDA is a suspension of stable microencapsulated gas bubbles with average diameter 2.0 microm prepared from sonicated dextrose albumin. The ultrasonic linear and nonlinear parameters, such as acoustic velocity, sound attenuation and acoustic nonlinearity parameter B/A of SDA, as a function of its bubble concentration from 1.0 x 10(7) to 2.05 x 10(8) microbubbles/mL in the frequency range of 2-6 MHz are measured in vitro. The sound attenuation coefficients over 2-6 MHz are linearly proportional to the bubble concentration and frequency. It is important to point out that the acoustic nonlinearity parameter B/A for SDA has a very large value that nonlinearly increases with the increase of bubble concentration.

Albumins↗
PubMed2000

One-year results of the vesta system for endometrial ablation.

STUDY OBJECTIVE: To compare a distensible multielectrode balloon for endometrial ablation with electrosurgical ablation performed by a combined resection-coagulation technique. DESIGN: Randomized, prospective trial (Canadian Task Force classification I). Setting. Eight centers. PATIENTS: Women with menorrhagia validated with a standardized pictorial blood loss assessment chart (PBAC), without intracavitary organic uterine disease, who failed or poorly tolerated medical therapy. Intervention. Results in 122 patients treated by Vesta and 112 treated surgically, evaluable at 1 year, were compared, with success defined as monthly blood loss of less than 80 ml and avoidance of additional therapy. MEASUREMENTS AND MAIN RESULTS: Pretreatment PBAC scores for patients treated by Vesta and resection or rollerball were 535+/-612 and 445 +/- 313, respectively; at 1 year they were 18+/-37 and 28+/-60, respectively. With PBAC below 75 as the definition of success, 86.9% of Vesta-treated patients were successful compared with 83.0% treated by rollerball or resection. Total amenorrhea, defined as no visible bleeding and no use of protective products, was 31.1% and 34. 8%, respectively. None of the outcome comparisons between treatments showed statistical difference. Complications in both groups were few and minor. Most (86.6%) Vesta procedures were carried out with paracervical block with or without intravenous sedation in an office or outpatient setting, compared with 79.7% epidural or general anesthesia for rollerball or resection. CONCLUSION: The Vesta system of endometrial ablation is equally effective and safe as classic resectoscopic methods. Potential advantages include avoidance of fluid and electrolyte disturbance associated with intravasation of distending media, and ability to perform the procedure under local anesthesia in an office setting with less total operating time.

Adult↗
PubMed2000

Influence of acute normovolaemic haemodilution on the dose-response and time-course of action of atracurium.

BACKGROUND: Acute normovolaemic haemodilution is a common method to save and avoid homologous blood transfusion during surgery. The aim of this study was to evaluate the influence of acute isovolaemic haemodilution on the dose-response and time-course of action of atracurium. METHODS: We studied 25 patients undergoing acute isovolaemic haemodilution during surgery and 25 patients not receiving haemodilution as a control group. All patients were ASA grade I and aged 18-54 yr. The haemodilution patients underwent major elective plastic surgery with an anticipated surgical blood loss of more than 600 ml, and the control patients underwent elective superficial plastic surgery with an anticipated surgical blood loss of less than 200 ml. Anaesthesia was induced with thiopental 4-6 mg/kg and fentanyl 2-4 microg/kg i.v., and maintained with 60% nitrous oxide in oxygen. After stabilization of anaesthesia, acute isovolaemic haemodilution in the haemodilution group was achieved by drainage of venous blood and an i.v. infusion of lactated Ringer's solution, and 6% dextran, during which haematocrit and haemoglobin decreased from 45.1% to 25.8% and from 147.2 g/l to 91.2 g/l, respectively. When anaesthesia was stable in the control group and haemodilution was completed in the haemodilution group, neuromuscular function was assessed by measuring with accelerography the response of the adductor pollicis muscle to supramaximal train-of-four (TOF) stimuli every 12 s to the ulnar nerve at the wrist via surface electrodes. The dose-response relationships of atracurium in the two groups were determined by the cumulative dose-response technique. RESULTS: The results showed that during haemodilution, the dose-response curve of atracurium was shifted to the left in a parallel fashion and the potency of atracurium was increased. In patients undergoing haemodilution, ED50, ED90 and ED95 of atracurium were decreased by 25-33%, and duration of action was increased by 21-48% following administration of the same dose (mg/kg), as compared with patients not undergoing haemodilution. CONCLUSION: We concluded that the patients undergoing acute isovolaemic haemodilution were about 30% more sensitive to neuromuscular blockade of atracurium and had a longer duration after administration of the same dose (microg/kg) than the control patients. Care must be taken with this problem when atracurium is used as a muscle relaxant during acute haemodilution.

Adolescent↗
PubMed2000

Clinicopathological features of aggressive large granular lymphocyte leukaemia resemble Fas ligand transgenic mice.

Fas ligand triggers cell death after interaction with its receptor Fas. Altered expression of Fas has been associated with lymphoproliferation and autoimmune disorders in both mice and man. Apoptosis of lung and liver tissue is seen in Fas ligand transgenic mice. It is not known whether constitutive expression of Fas ligand can cause a similar human disease. Four patients with aggressive large granular lymphocyte (LGL) leukaemia involving lung and liver were studied. All four patients were severely ill with pulmonary involvement. Two patients presented with hypoxia and were oxygen dependent; the other two patients had severe pulmonary hypertension. Lung biopsies showed interstitial infiltration by leukaemic LGL. The infiltrating lymphocytes expressed both Fas and Fas ligand, whereas normal pneumocytes expressed only Fas. Similar findings were observed in liver biopsies from these patients. Features mimicking the pathological changes of graft-versus-host disease were observed, including pneumocyte apoptosis. All four patients had high levels of circulating Fas ligand. Successful treatment with oral methotrexate or 2-chlorodeoxyadenosine was associated with disappearance or marked reduction of circulating Fas ligand. These results suggest that dysregulated expression of Fas ligand can lead to human disease with pathological features resembling graft-versus-host disease.

Adult↗
PubMed2000

Single-stage laryngotracheal reconstruction in children: a review of 200 cases.

OBJECTIVE: We reviewed our experience with pediatric single-stage laryngotracheal reconstruction (SSLTR) to identify factors that affect postoperative outcomes, including the need for reintubation and tracheostomy. STUDY DESIGN: Retrospective chart review was done. RESULTS: In total, 190 children underwent 200 SSLTRs; 29% were reintubated, and 15% required postoperative tracheostomy. Currently, 96% are decannulated. The use of anterior and posterior costal cartilage grafting, age less than 4 years, sedation for more than 48 hours, a leak pressure around the endotracheal tube at greater than 20 cm H2O, and moderate/severe tracheomalacia significantly increased the rate of reintubation. The duration of stenting did not affect outcomes. Children with anterior and posterior grafts and those with moderate or severe tracheomalacia were more likely to need a postoperative tracheostomy. CONCLUSION: SSLTR can be effective for the treatment of pediatric laryngotracheal stenosis. Diligent preoperative assessment of the patient and the patient's airway and close postoperative care are important to the success of this operation.

Adolescent↗
PubMed2000

Circadian variations of prostaglandins in the rabbit aqueous humor.

Forty-eight young adult New Zealand albino rabbits were entrained to a daily 12-hr light and 12-hr dark cycle. Under a constant dark environment, rabbits were sacrificed at 4-hr intervals, beginning at 2 hr before the accustomed lights-on period. Eight rabbits were used for each of the 6 time points within 24 hr. Aqueous humor and vitreous humor samples were collected. Samples from one eye of each rabbit were assayed for prostaglandins D2, E2, and F2alpha by enzyme immunoassay. Total protein concentrations in the samples were also determined. Concentrations of prostaglandins D2 and F2alpha in the aqueous humor were found to vary in a consistent pattern. The prostaglandin F2alpha concentration increased in the early subjective light period, remained high in this period, and decreased in the subjective dark period. The prostaglandin D2 concentration was elevated only in the early subjective light period. No significant change of aqueous humor prostaglandin E2 level was found. Total protein concentration in the aqueous humor varied in a similar pattern as the aqueous humor prostaglandin F2alpha, indicating a close association between the permeability of protein across the blood-aqueous barrier and the endogenous prostaglandin F2alpha level. In the vitreous humor, concentrations of all three prostaglandin subtypes remained unchanged, as did the total protein concentration. However, vitreous humor concentrations of prostaglandin D2 and F2alpha were significantly higher than their concentrations in the aqueous humor.

Animals↗
PubMed2000

Preoperative carcinoembryonic antigen level as an independent prognostic factor in colorectal cancer: Taiwan experience.

BACKGROUND: Preoperative carcinoembryonic antigen (CEA) level is considered as a factor predictive of survival in colorectal cancer patients. Patients with normal (<5 ng/ml) or lower preoperative CEA levels were reported to have significantly longer survival. This study was carried out in an effort to evaluate the prognostic significance of preoperative CEA levels of patients with colorectal cancer in Taiwan. METHODS: Between 1990 and 1994, 218 patients with histologically confirmed colorectal cancers were evaluated retrospectively at the Veterans General Hospital-Taipei. All the patients had undergone potentially curative surgery. Patients with metastatic diseases were not included. 5-Fluorouracil-based adjuvant chemotherapy was administered if the patients had Dukes' C disease. Reference to the Dukes' classification was according to the classical criteria described in 1932 for carcinoma of the rectum and adapted for use in colonic tumors. Data on gender, age, degree of tumor differentiation, location of the tumor, tumor size, lymph node metastasis, penetration of the bowel wall and preoperative CEA levels were analyzed to determine their association with survival. Blood samples for CEA measurement were taken a few days before operation and were analyzed using the radioimmunoassay method. Multivariate analysis by Cox's proportional hazards regression model was performed to determine the most important predictors of survival among all of the possible variables. RESULTS: By univariate analysis, the size of the tumor (p = 0.012), lymph node metastases (p = 0.007), penetration of the bowel wall (p < 0.001) and preoperative CEA levels (p < 0.001) were found to be significant prognostic factors, while gender, age, degree of tumor differentiation and location of the tumor were not significant. By multivariate Cox analysis, lymph node metastases (p = 0.003), penetration of the bowel wall (p = 0.0001) and preoperative CEA levels (p = 0.0001) were found to be independent prognostic factors in colorectal cancer patients. CONCLUSIONS: The data from our study indicate that in addition to lymph node metastases and penetration of the bowel wall, the preoperative CEA levels are also an independent prognostic factor in non-metastatic colorectal cancer patients after curative surgery. This could serve as an appropriate modification to the initial Dukes' scheme in colorectal cancer.

Adenocarcinoma↗
PubMed2000

Venous gangrene in a patient with adenocarcinoma of the lung.

Cancer-related thromboembolism is a severe but not uncommon paraneoplastic syndrome in mucinous cancer patients. However, cancer-induced venous gangrene is extremely rare and has never been reported in the English literature. Here, we present a case of lung cancer complicated with venous gangrene of the left foot. An elevated serum anticardiolipin level was detected during hospitalization, but the patient's clinical condition stabilized after heparinization. We suggest that in cancer patients, an elevated serum anticardiolipin antibody level might be a warning sign of an impending thrombotic event and that low-molecular-weight heparin is a sensible choice in treating this kind of cancer-related thromboembolism.

Adenocarcinoma↗
PubMed2000

Phase II study of oral tegafur-uracil and folinic acid as first-line therapy for metastatic colorectal cancer: Taiwan experience.

BACKGROUND: Tegafur-uracil has become an important regimen in the treatment of metastatic colorectal cancer. Tegafur is a prodrug that is converted to 5-fluorouracil (5-FU) and has been reported to be less toxic and to have a higher therapeutic index. The additional advantage of tegafur is oral administration, an important consideration to improve the quality of life in these patients. Tegafur in combination with uracil is thought to have greater anti-tumor activity due to the inhibitory effect of uracil on the degradation of 5-FU by hepatic dihydropyrimidine dehydrogenase. Tegafur with folinic acid has been reported with modest efficacy and acceptable toxicity. The purpose of this study was to evaluate the effectiveness and toxicity profile of oral tegafur-uracil plus folinic acid in Chinese patients with metastatic colorectal cancer. METHODS: Between May 1998 and August 1999, 40 patients with metastatic colorectal carcinoma were enrolled in this study. All the patients had to have measurable lesions. The initial dose of tegafur-uracil was 300 mg/m2/day for 28 days, followed by a 7-day rest period. Folinic acid was administered orally at a dose of 60 mg/day concurrently with tegafur-uracil. For patients with neutrophil count <1500/microl or a platelet count <100,000/microl after treatment, the treatment was postponed for a maximum of 2 weeks. After that time, if the neutrophil count was 1000-1500/microl and the platelet count was 70,000-100,000 microl, the dose of tegafur-uracil was reduced by 50%, and if lower values resulted, the treatment was discontinued. RESULTS: Forty patients received a total of 318 courses of treatment and a response rate of 32.5% (95% CI, 18-47%), including five complete remissions and eight partial remissions, was achieved. Toxicity was mild and generally tolerable. Gastrointestinal toxicities, including diarrhea, nausea and vomiting, were the major side effects. Seven incidences (17.5%) of grade 3-4 gastrointestinal toxicity were observed. Hematological toxicities were minimal with no evidence of severe (grade 3 or 4) leukopenia and thrombocytopenia. No episode of hepatic, renal, cardiac or neurological toxicity occurred. Two patients (5%) developed transient painful fissuring erythroderma over their palms and soles (the hand-foot syndrome). CONCLUSIONS: The data from our study indicate that oral tegafur-uracil plus folinic acid is an active and tolerable first-line treatment for Chinese patients with metastatic colorectal cancer, with the additional advantage of being easily administered at home.

Adenocarcinoma↗