Biomedical subjects

C M Lin

Publications and source records attributed to C M Lin.

At least 19 recordsLinked to original sources

PubMed2001

Interleukin-10-induced T cell unresponsiveness can be reversed by dendritic cell stimulation.

The secretion of immunosuppressive factors like interleukin-10 (IL-10), either by tumor cells or by tumor-infiltrating leukocytes, has been recognized as one of the mechanisms involved in tumor immunological escape and a serious obstacle for successful immunotherapy. Therefore, any therapeutic attempts aimed at inducing antitumor immunity in tumor-bearing hosts must overcome this immunosuppressive state. This study aimed to determine whether dendritic cell (DC) immunization, a promising approach to induce antitumor immunity, could break IL-10-induced anergic state in CD4+ T cells, essential cells in generating tumor-specific immunity. We found that the ability of DC to reverse IL-10-induced anergic state in human CD4+ T cells is dependent on the IL-10 concentration that T cells have been exposed to and the degree of DC maturation. The efficacy of mature DC in reversing T cell anergy can be mimicked by higher cell numbers of immature DC. In addition, activated T cells induced by DC stimulation are sensitive to IL-10 treatment. Collectively, our results suggest the use of mature DC and the necessity of antagonizing the action of tumor-derived IL-10 in immunotherapy of cancer with DC immunization.

CD4-Positive T-Lymphocytes↗

PubMed2001

Anterior mediastinal tumour identified by intraoperative transesophageal echocardiography.

PURPOSE: To report a child with anterior mediastinal tumour misdiagnosed as pericardial effusion who had been sent to the operating theatre for drainage. After induction of general anesthesia she developed cardio-respiratory collapse. The diagnosis was made with the aid of transesophageal echocardiography (TEE). CLINICAL FEATURES: A 14-yr-old girl suffered from cough and intermittent fever for one month before admission. Four days before admission, she became orthopneic and was admitted to the intensive care unit. Precordial echocardiography showed an anterior and posterior echolucent space between the pericardium and epicardium that was thought to be a pericardial effusion. She was sent to the operating room for emergency drainage. After induction of general anesthesia, breath sounds were not heard on the left side of the chest. The patient developed increasing hypoxemia and hypotension despite cardiocentesis. A TEE determined that an anterior mediastinal mass was the cause of her hypoxemia and hypotension. The tumour was debulked and the patient made an uneventful postoperative recovery. CONCLUSION: In this case, the correct diagnosis of an anterior mediastinal mass was made with TEE. The place of TEE may be indicated in patients with unexplained hypoxemia and hypotension.

Child↗

PubMed2001

Dehydroepiandrosterone sulfate (DHEAS) suppresses P2X purinoceptor-coupled responses in PC12 cells.

Some steroids rapidly alter neuronal excitability through interaction with neurotransmitter-gated ion channels in addition to their well-known genomic effects via intracellular steroid receptors. Such effects were found in GABA receptor, nicotinic receptors, yet not investigated in P2X purinoceptors. In this study, the effects of dehydroepiandrosterone sulfate on the P2 purinoceptor was investigated. Results show that dehydroepiandrosterone sulfate acutely inhibits P2X purinoceptor functions in PC12 cells. Dehydroepiandrosterone sulfate suppressed ATP-induced cytosolic free calcium concentration ([Ca(2+)](i)) rise, cytosolic free sodium concentration ([Na(+)](i)) rise, and dopamine secretion in the presence of external calcium, but had no effect on ATP-induced [Ca(2+)](i) rise in the absence of external calcium or on UTP-induced [Ca(2+)](i) rise in the absence or presence of external calcium. Our data show that dehydroepiandrosterone sulfate exerted its effect on P2X, but not on the P2Y purinoceptors found in PC12 cells. Estradiol and estrone have similar effects on P2X purinoceptor, but dehydroepiandrosterone and progesterone do not.

Adenosine Triphosphate↗

PubMed2001

Glutamine metabolism in sepsis and infection.

Severe infection causes marked derangements in the flow of glutamine among organs, and these changes are accompanied by significant alterations in regional cell membrane transport and intracellular glutamine metabolism. Skeletal muscle, the major repository of glutamine, exhibits a twofold increase in glutamine release during infection, which is associated with a significant increase in endogenous glutamine biosynthesis. Despite an increase in glutamine synthetase activity in skeletal muscle, the intracellular glutamine pool becomes depleted, indicating that release rates exceed rates of synthesis. Simultaneously, the circulating pool of glutamine does not increase, indicating accelerated uptake by other organs. The liver appears to be the major organ of glutamine uptake in severe infection; studies in endotoxemic rodents have shown net hepatic glutamine uptake to increase by as much as 8- to 10-fold. This increase is due partially to increases in liver blood flow, but also to a three- to fourfold increase in hepatocyte System N activity in the liver. Cytokines and glucocorticoids mediate the increased uptake of glutamine by the liver in septic states as well as other compounds. Sepsis does not appear to induce an increase in System N gene expression, indicating that the increase in hepatic glutamine transport observed during severe infection is probably regulated at the protein level. The bowel displays a decrease in glutamine utilization during sepsis, a response that may be related to the decrease in circulating insulin-like growth factor-1 (IGF-1) levels that is characteristic of sepsis. Recent studies suggest that IGF-1 has a direct effect on stimulating glutamine transport across the gut lumen and thus may represent a therapeutic avenue for improving gut nutrition during severe infection. The cells of the immune system (lymphocytes, macrophages) are also major glutamine consumers during inflammatory states in which cell proliferation is increased. Under these conditions, glutamine availability can become rate limiting for key cell functions, such as phagocytosis and antibody production.

Animals↗

PubMed2001

Destruction of Escherichia coli O157:H7 and Salmonella enteritidis in cow manure composting.

Application of cow manure and composted manure in agricultural practice could potentially cause contamination of foodstuffs with pathogenic bacteria such as Salmonella Enteritidis and Escherichia coli O157:H7. In this study, rifampicin-resistant (RifR) E. coli O157:H7 and Salmonella Enteritidis at a level of 7 log CFU/g of raw compost feed were used to determine the effect of a bench-scale composting system on their survival. RifR E. coli O157:H7 was not detected after 72 h of composting at 45 degrees C, and RifR Salmonella Enteritidis was not detected after 48 h. The use of selective media for enrichment failed to recover in the composting samples held at 45 degrees C for 96 h. However, the pathogens showed no change in bacterial numbers when the composting system was held at room temperature. Thus, properly composted manure can be safely used in food crop production while minimizing the likelihood of microbial contamination.

Animals↗

PubMed2001

Pneumopericardium after bronchoscopic carbon dioxide laser surgery--a case report.

A female baby sustained pneumopericardium after bronchoscopic CO2 laser surgery for tracheal stenosis. Perioperative pneumopericardium though rare is a life-threatening condition in babies. The symptoms are usually not specific such as hypotension, bradycardia, muffled heart sound, cardiovascular collapse, etc. The causes and clinical findings of pneumopericardium were reviewed, as are the radiographic features so as to differentiate the condition from pneumomediastinum. Early recognition of pneumopericardium is important, because emergent pericardiocentesis may be required if there is clinical evidence of cardiac tamponade.

Bronchoscopy↗

PubMed2001

Hemodynamic responses of thiopental and propofol in different-aged patients during endotracheal intubation.

BACKGROUND: Thiopental and propofol are 2 popularly used anesthetic induction agents that have different pharmacological and pharmacokinetic actions. It is not clear how the hemodynamic responses differ in different-aged patients using these 2 drugs for anesthetic induction. The aim of this study was to investigate the hemodynamic responses to propofol and thiopental of different-aged patients during endotracheal intubation. METHODS: Sixty patients, 20 to 83 years old, were included in this study. Patients were randomly divided into 6 groups according to age and different inductive anesthetics. Non-invasive blood pressure (NIBP) monitoring was performed every minute before anesthesia, during anesthetic induction with 5 mg.kg-1 thiopental or 2 mg.kg-1 propofol intravenously, and after intubation. RESULTS: Propofol induction produced a smaller mean arterial pressure increase immediately after intubation than did thiopental induction in adult and elderly groups (101.0 +/- 18.5 and 104.0 +/- 21.1 mmHg in the propofol groups vs. 138.3 +/- 17.1 and 138.9 +/- 16.1 mmHg in the thiopental groups at 1 minute after intubation, p < 0.001 and p = 0.001, respectively). Differences in heart rate between propofol and thiopental groups were found in young and adult groups (85.1 +/- 9.2 and 81.7 +/- 10.9 in the propofol groups vs. 94.5 +/- 9.9 and 95.0 +/- 14.0 beats per minute in the thiopental groups at 1 minute after intubation, p = 0.041 and p = 0.029, respectively). CONCLUSION: Propofol induction produced more stable hemodynamics after intubation in adult and elderly patients than did thiopental induction. Therefore, it is safer to use propofol for induction and intubation in adult and elderly patients.

Adult↗

PubMed2001

Combined conventional and jet ventilation in airway management in tracheal tumor.

Tumors on the carina are uncommon, and their anesthetic management can present a considerable challenge. The principle anesthetic consideration is ventilation and oxygenation in the face of an open airway. A 60-year-old man patient suffered a carinal tumor, which occupied 70% of the both main bronchi and bled spontaneously while coughing. Surgical resection and reconstruction were done. The carinal surgical approach was a right posterolateral thoracotomy, and the patient was placed in the left decubitus position. Because we could not insert the jet catheter past the mass, high frequency jet ventilation to ventilate the dependent lung could not be applied. Our choice was differential lung ventilation with a combination of conventional and high frequency jet ventilation modes to preserve oxygenation during tumor excision and tracheal reconstruction. An episode of desaturation was successfully treated during removal of tumor. The postoperative course was uneventful. The patient was sent to the intensive care unit after surgery and discharged on the 11th day. He received further combined chemotherapy and radiotherapy during his next admission. Fiberoptic examination on the 5 months later no evidence of recurrence. In summary, we described our airway management on carinal tumor excision, especially the tumor was so large that dependent lung jet ventilation could not employ.

High-Frequency Jet Ventilation↗

PubMed2001

Inadvertent hypothermia causes pulseless electrical activity in a patient during cervical spine surgery--a case report.

Recent studies have shown that hypothermia triples the incidence of major cardiac events. We present a happening in which a 71-year-old patient developed pulseless electrical activity (PEA) while he was undergoing cervical laminectomy for spinal stenosis in the sitting position. Thromboembolism or venous air embolism and acute myocardial infarction were respectively excluded by transesophageal echocardiography and cardiac enzymes analysis to be the causes of the cardiac event. The abnormal finding that stood out was low nasopharyngeal temperature (31 degrees C) during the procedure, which was thought to contribute to the development of the PEA episode.

Aged↗

PubMed2000

Cloning and functional characterization of a constitutively expressed nitrate transporter gene, OsNRT1, from rice.

Elucidating how rice (Oryza sativa) takes up nitrate at the molecular level could help improve the low recovery rate (<50%) of nitrogen fertilizer in rice paddies. As a first step toward that goal, we have cloned a nitrate transporter gene from rice called OsNRT1. OsNRT1 is a new member of a growing transporter family called PTR, which consists not only of nitrate transporters from higher plants that are homologs of the Arabidopsis CHL1 (AtNRT1) protein, but also peptide transporters from a wide variety of genera including animals, plants, fungi, and bacteria. However, despite the fact that OsNRT1 shares a higher degree of sequence identity with the two peptide transporters from plants (approximately 50%) than with the nitrate transporters (approximately 40%) of the PTR family, no peptide transport activity was observed when OsNRT1 was expressed in either Xenopus oocytes or yeast. Furthermore, contrasting the dual-affinity nitrate transport activity of CHL1, OsNRT1 displayed only low-affinity nitrate transport activity in Xenopus oocytes, with a K(m) value of approximately 9 mM. Northern-blot and in situ hybridization analysis indicated that OsNRT1 is constitutively expressed in the most external layer of the root, epidermis and root hair. These data strongly indicate that OsNRT1 encodes a constitutive component of a low-affinity nitrate uptake system for rice.

Amino Acid Sequence↗

PubMed2000

T cell receptor binding kinetics and special role of Valpha in T cell development and activation.

The kinetics of the interaction between T cell receptor (TCR) and major histocompatibility complex (MHC) has an important role in determining thymocyte-positive and -negative selection in the thymus, as well as in T cell activation. The alpha chain of the TCR is the major player in determining how the TCR fits onto the MHC ligand, and thus has a major role in determining whether a T cell develops as class I or class II restricted. In this article, we summarize recent data from our laboratory and others on the role of polymorphism in the Valpha combining site in determining MHC class restriction, and on kinetic parameters in thymocyte selection.

Animals↗

PubMed2000

Bactericidal activity of isothiocyanate against pathogens on fresh produce.

The bactericidal activity of allyl and methyl isothiocyanate (AITC and MITC) was tested with a rifampicin-resistant strain of Salmonella Montevideo and streptomycin-resistant strains of Escherichia coil O157:H7 and Listeria monocytogenes Scott A. Iceberg lettuce inoculated with high (10(7) to 10(8) CFU/g) and low (10(3) to 10(4) CFU/g) concentrations of bacterial pathogens was treated with AITC and MITC in sealed containers at 4 degrees C for 4 days. AITC showed stronger bactericidal activity than MITC against E. coli O157:H7 and Salmonella Montevideo, whereas MITC showed stronger activity against L. monocytogenes than E. coli O157:H7 and Salmonella Montevideo. Up to 8-log reduction occurred with E. coli O157:H7 and Salmonella Montevideo on lettuce following treatment with vapor generated from 400 microl of AITC for 2 and 4 days, respectively. AITC was used to treat tomatoes inoculated with Salmonella Montevideo on stem scars and skin and apples inoculated with E. coli O157:H7 on stem scars. The bactericidal effect of AITC varied with bacteria species and exposure time. Salmonella Montevideo inoculated on tomato skin was more sensitive to AITC than that on stem scars. Treatment with vapor generated from 500 microl of AITC caused an 8-log reduction in bacteria on tomato skin but only a 5-log reduction on tomato stem scars. The bactericidal activity of AITC was weaker for E. coli O157:H7 on apple stem scars; only a 3-log reduction in bacteria occurred when 600 microl of AITC was used.

Dose-Response Relationship, Drug↗

PubMed2000

Antibacterial mechanism of allyl isothiocyanate.

Allyl isothiocyanate (AITC), a natural compound in plants belonging to the family Cruciferae, has been shown to have strong antimicrobial activity in liquid media as well as in its vapor form. To understand its antimicrobial mechanism, AITC was tested for bactericidal activities to Salmonella Montevideo, Escherichia coli O157:H7, and Listeria monocytogenes Scott A at different stages of growth and was compared with streptomycin, penicillin G, and polymyxin B, each of known antibacterial mechanisms. Bactericidal activities were determined by measuring bacterial viability and leakage of metabolites. To determine its effects on membrane permeability, beta-galactosidase activity was examined after exposure of E. coli K-12 strain 3.300 to the three antibiotics and to AITC. The two gram-negative bacteria, Salmonella Montevideo and E. coli O157:H7, were more sensitive to AITC and to polymyxin B than the gram-positive L. monocytogenes. AITC and polymyxin B were effective bactericidal agents to bacteria at all growth stages, whereas penicillin G and streptomycin did not exhibit bactericidal activity to stationary cells. High A260 and A280 values of cellular filtrate and beta-galactosidase activity were obtained after treatments of AITC and polymyxin B. These data indicated that AITC was most similar to polymyxin B with respect to its antibacterial effect on cell membranes and on leakage of cellular metabolites. Gaseous AITC caused metabolite leakages, measurable increases in 3-galactosidase activity, and reduction of viable bacteria. The effectiveness of AITC in inhibiting bacteria at all growth stages and its strong activity in vapor phase support its application in food preservation.

Cell Membrane Permeability↗

PubMed2000

Effects of VEGF121 and/or VEGF165 gene transfection on collateral circulation development.

BACKGROUND AND PURPOSE: Angiogenesis is regulated by various factors, including vascular endothelial growth factor (VEGF). Five isoforms of VEGF have been discovered: VEGF121, VEGF145, VEGF165, VEGF189, and VEGF206. The teleologic basis for the various VEGF isoforms remains unclear, but different VEGF isoforms may mediate distinct endothelial cell functions such as angiogenesis, vascular permeability, and differentiation. We sought to determine the effects of various VEGF isoforms on angiogenesis under ischemic conditions in rabbits. METHODS: The effects of VEGF121 and/or VEGF165 gene transfection on collateral circulation development in ischemic rabbit hindlimb muscles were investigated by using naked plasmids encoding VEGF121 or VEGF165 (pVEGF121 or pVEGF165), either individually or in combination. pCMV beta was used as the control plasmid. The femoral artery on one side of New Zealand White rabbits was ligated. Ten days later, the ischemic muscles received direct intramuscular injection of pVEGF121 (500 micrograms), pVEGF165 (500 micrograms), or pVEGF121 (250 micrograms) + pVEGF165 (250 micrograms) in experimental groups, while pCMV beta (500 micrograms) was used in the control group. Therapeutic effects were evaluated 30 days later by anatomic and physiologic analysis. RESULTS: Internal iliac angiography showed strong development of collateral circulation in all of the pVEGF-treated groups. In contrast, collateral arteries developed weakly in the control group. Combination treatment with both pVEGF121 and pVEGF165 did not result in additional improvement compared with pVEGF121 or pVEGF165 treatment alone (angiographic scores: pVEGF121 = 0.85 +/- 0.10; pVEGF165 = 0.81 +/- 0.11; pVEGF121 + pVEGF165 = 0.83 +/- 0.09; control = 0.53 +/- 0.09; p < 0.01). A favorable response in the development of circulation at the capillary level with pVEGF121 and/or pVEGF165 versus pCMV beta was also found. Blood pressure measurement and regional blood flow measurement using colored microspheres revealed similar results. CONCLUSIONS: Our results show that direct intramuscular injection of naked DNA encoding VEGF121 or VEGF165, individually or in combination, is an effective method for gene transfer in an animal model of ischemic limbs and results in augmented collateral vascular development and tissue perfusion.

Angiography↗

PubMed2000

Respiratory management after self-extubation.

BACKGROUND AND PURPOSE: Self-extubation is a potentially life-threatening event, but may also provide an opportunity to wean patients who should have been extubated earlier. The purpose of this study was to determine the risk factors for re-intubation after self-extubation. METHODS: The medical charts of 69 self-extubated patients treated in Shin Kong Hospital, Taipei, from September 1996 through August 1998 were reviewed. Demographic data, ventilator settings before self-extubation, arterial blood gas values, and the type of respiratory management used after self-extubation were examined to determine their association with re-intubation. RESULTS: Of the 69 self-extubated patients, 38 fared well without further ventilatory support after self-extubation. Four factors were associated with extubation outcome: 1) mean pre-extubation FiO2 (fraction of inspired oxygen), which was significantly higher in the re-intubated group (RI) than in the not re-intubated group (NRI) (0.48 vs 0.33, p = 0.002)--all self-extubated patients receiving an FiO2 of more than 0.40 were re-intubated; 2) PaO2/FiO2 (ratio of arterial oxygen tension to inspired oxygen concentration), which was lower in the RI group than in the NRI group (259.4 vs 346.4, p = 0.005); 3) requirement for assist/control ventilatory mode--patients needing this type of ventilatory support had a greater likelihood of reintubation than those requiring partial ventilatory support (odds ratio [OR], 3.790; confidence interval [CI], 1.055-13.621; p = 0.041); and 4) female sex (OR 0.188; CI 0.048-0.732; p = 0.016). CONCLUSIONS: About half of self-extubated patients may not require re-intubation. Pre-extubation FiO2, PaO2/FiO2, and ventilator mode, as well as gender, may be useful in determining the likelihood that a self-extubated patient will require re-intubation.

Adult↗

PubMed2000

Anesthesia of CO2 laser surgery in a patient with Hunter syndrome: case report.

Hunter syndrome (mucopolysaccharidosis, type II; MPS II) is one of a heterogeneous group of recessively inherited mucopolysaccharide storage diseases. Patients with mucopolysaccharidosis show progressive involvement and derangement of many organs, especially upper airway anomalies, which are the major cause of perioperative death. In recent years, a CO2 laser is often applied to upper airway lesions. A 16-year-old patient suffering from Hunter syndrome was scheduled for CO2 laser surgery because of sleep apnea and respiratory stridor. Otolaryngological examination revealed bulging of the bilateral false cord with stenosis of the glottis. We adopted sevoflurane mask induction and high-frequency jet ventilation to overcome the perioperative airway problems. The anesthetic course was uneventful, and the patient was discharged 2 days after the operation.

Adolescent↗

PubMed1999

Mouse endostatin inhibits the formation of lung and liver metastases.

Angiogenesis is required for tumor formation. Several studies have demonstrated that tumor angiogenesis is regulated by a balance between proangiogenesis and antiangiogenesis factors and that this balance varies in different organ environments. To investigate whether expression of an angiogenesis inhibitor by cancer cells could alter this balance and prevent tumor formation in different organ environments, we engineered stable transfectants from RenCa mouse renal carcinoma cells and SW620 human colon carcinoma cells to constitutively secrete a mouse endostatin protein with c-myc and polyhistidine (His) tags. Production and secretion of the endostatin-c-myc-His fusion protein by endostatin-transfected cells were confirmed by immunofluorescence staining and Western blot analysis. The endostatin transfectants and control transfectants, stably transfected with a control plasmid, had similar in vitro growth rates compared with their parental cell lines. Conditioned medium from endostatin-transfected cells inhibited human umbilical vein endothelial cell proliferation by 36-51% compared with conditioned medium from control cells. After inoculation into mice, flank tumors from endostatin-transfected cells were 73-91% smaller than flank tumors from control cells after 3 weeks. Inoculation of a cell mixture containing 25% endostatin-transfected cells and 75% control cells resulted in inhibition of flank tumor formation as effective as after inoculation of 100% endostatin-transfected cells. Formation of lung metastases by RenCa endostatin-transfected cells and formation of liver metastases by SW620 endostatin-transfected cells were dramatically inhibited compared with formation of metastases by control cells. These findings demonstrate that endostatin can inhibit tumor formation in different organ environments and that gene delivery of endostatin into even a minority of tumor cells may be an effective strategy to prevent progression of micrometastases to macroscopic disease.

Animals↗

PubMed1999

Cutting edge: trimolecular interaction of TCR with MHC class II and bacterial superantigen shows a similar affinity to MHC:peptide ligands.

Bacterial superantigens such as Staphylococcus aureus enterotoxin A (SEA) are very potent stimulators of T cells. They bind to the Vbeta region of the TCR and to MHC class II, stimulating T cells at nanomolar concentrations. Using surface plasmon resonance measurements, we find that binding between the individual components of the complex (TCR-class II, TCR-SEA, SEA-class II) is very weak, but that the stability of the trimolecular complex is considerably enhanced, reaching an affinity similar to that found for TCR interactions with MHC:peptide ligand. Thus, the potency of SEA in stimulation of T cells is not due to particularly strong affinities between the proteins, but to a cooperative effect of interactions in the TCR-SEA-MHC class II trimolecular complex that brings the kinetics into a similar range to binding of conventional Ags. This range may be the optimum for T cell activation.

Animals↗