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Biomedical subjects

L Chu

Publications and source records attributed to L Chu.

At least 19 recordsLinked to original sources
PubMed2005

Upregulation of T-bet expression in peripheral blood mononuclear cells during Vogt-Koyanagi-Harada disease.

AIM: To test the hypothesis that T-bet expression is altered in patients with Vogt-Koyanagi-Harada (VKH) disease. METHODS: Peripheral blood was withdrawn from 16 VKH patients before and after immunosuppressive treatment and from 16 healthy individuals. IFN-gamma, IL-2, and IL-4 in the serum and the supernatants of peripheral blood mononuclear cells (PBMC) cultured with or without phytohaemagglutinin (PHA) were measured by ELISA. T-bet mRNA and protein expression in PBMC cultured with or without PHA was detected by RT-PCR and western blot, respectively. RESULTS: The level of IFN-gamma, but not IL-2 and IL-4, was significantly higher in the supernatants of stimulated PBMC in patients than in controls. A significantly increased T-bet mRNA was found in VKH patients during an active uveitis episode, but not in quiescent patients, compared to controls. T-bet protein was detectable in VKH patients during an active uveitis episode, but not in quiescent patients nor in the healthy controls. Stimulation of PBMC with PHA resulted in a marked upregulation of T-bet mRNA and protein expression for both patients and controls with no significant difference between the two groups. CONCLUSIONS: Upregulation of T-bet may be associated with the development of a Th1 mediated immune response in VKH disease.

Adult↗
PubMed2002

Effects of androstenedione on long term potentiation in the rat dentate gyrus. Relevance for affective and degenerative diseases.

We studied the effects of the androgenic hormone androstenedione, a 17-ketosteroid, on long term potentiation (LTP) in the dentate gyrus (DG) of intact, urethane anesthetized rats. Intravenous injection of 10mg of the hormone dissolved in Nutralipid produced a significant increase of the population spike (PS), but not of the excitatory post-synaptic potentials (EPSPs). The results are discussed in terms of the potential enhancement that androstenedione may have on some aspects of memory processes as reported for other androgenic steroids. Also noted are the plausible beneficial effects of the hormone on depression as well as in recovery following both central and peripheral neural injury.

Action Potentials↗
PubMed2001

Initial structure-activity relationship of a novel class of nonpeptidyl GnRH receptor antagonists: 2-arylindoles.

A nonpeptidyl GnRH receptor antagonist (1), with a unique 2-arylindole core, was identified through the Merck in-house screening for binding affinity on the rat GnRH receptor. SAR studies directed toward the alkoxy-ethanolamine and 2-aryl groups resulted in a simpler lead structure with improved activity. This compound 50 exhibits a 60-fold improvement in binding activity over our initial lead 1.

Animals↗
PubMed2001

Industrial choices for protein production by large-scale cell culture.

Traditional barriers to large-scale mammalian culture have now been addressed, with the standard stirred-tank reactor emerging as industry's technology of choice. The issues of adapting cells to suspension culture, shear sensitivity and oxygen supply have been largely resolved. But for many low-volume and specialty applications, such as the production of viral vaccines and gene therapies, reactor technology remains diversified, with reactor types ranging from roller bottles to stacked plates and hollow fibers.

Animals↗
PubMed2001

Positive inotropic effect of alpha 1-adrenoceptor stimulation in dog ventricular myocardium.

Stimulation of cardiac alpha1-adrenoceptors elicits a positive inotropic effect (PIE) in ventricular myocardium of most mammalian species, but not that of the dog. Stimulation of alpha1-adrenoceptors by phenylephrine did not affect the contractile force in isolated dog ventricular trabeculae under control conditions at 0.5 Hz at 37 degrees C. Phenylephrine, however, induced a definite PIE under experimental conditions at a low frequency (0.1 Hz) and low temperature (29 degrees C). Endothelin-1 and angiotensin II, the Gq protein-coupled receptors (GqPCR) of which are coupled to Gq protein-mediated stimulation of phosphoinositide (PI) hydrolysis as phenylephrine, did not affect the contractile force under control conditions either. But they did produce PIE at 0.1 Hz at 29 degrees C. These findings indicate that stimulation of receptors that are coupled to acceleration of PI hydrolysis has the potential to produce a PIE, but the expression of the effect of stimulation of GqPCR including alpha1-adrenoceptors is prevented at signaling processes that are susceptible for stimulation frequency and experimental temperature in dog ventricular myocardium.

Adrenergic alpha-1 Receptor Agonists↗
PubMed2001

Effects of alcohol on blood pressure and production of vascular aldosterone and corticosterone.

AIMS: The aims of this study were to search for the role of alcohol in blood pressure regulation in rats and to investigate the effects of alcohol on the production of vascular aldosterone and corticosterone. METHODS: Male Wistar rats received alcohol 0.7 g x kg(-1) x day(-1) (alcohol-treated group 1) or 1.4 g x kg(-1) x day(-1) (alcohol-treated group 2) or 2.1 g x kg(-1) x day(-1) (alcohol-treated group 3), orally, for 3 months, and blood pressure was monitored by a pressure transducer. Systolic blood pressure increased in Wistar rats treated with alcohol compared to control rats. Mesenteric artery perfusion ex vivo was performed and pressor responses to norepinephrine were determined. The pressor responses to norepinephrine in mesenteric arteries treated with alcohol were significantly increased. The perfusate from the mesenteric arteries was collected and applied to a Sep-Pak C 18 cartridge column for reverse-phase high-performance liquid chromatography and aldosterone and corticosterone levels were determined by radioimmunoassay, aldosterone was decreased but corticosterone was increased in the perfusate from arteries treated with alcohol. RESULTS: Reverse transcriptase polymerase chain reaction showed that alcohol inhibited the expression of 11beta-HSD2 and CYP11B2 mRNA in mesenteric arteries. CONCLUSIONS: These results reveal that alcohol is able to induce hypertension and provide evidence that alcohol inhibits the transcriptions of both 11beta-HSD2 and CYP11B2 in the vasculature, leading to lower aldosterone and higher corticosterone production in vessels, and increased vasoconstrictor responses to norepinephrine.

11-beta-Hydroxysteroid Dehydrogenase Type 2↗
PubMed2000

Functional analysis of gapped microbial genomes: amino acid metabolism of Thiobacillus ferrooxidans.

A gapped genome sequence of the biomining bacterium Thiobacillus ferrooxidans strain ATCC23270 was assembled from sheared DNA fragments (3.2-times coverage) into 1,912 contigs. A total of 2,712 potential genes (ORFs) were identified in 2.6 Mbp (megabase pairs) of Thiobacillus genomic sequence. Of these genes, 2,159 could be assigned functions by using the WIT-Pro/EMP genome analysis system, most with a high degree of certainty. Nine hundred of the genes have been assigned roles in metabolic pathways, producing an overview of cellular biosynthesis, bioenergetics, and catabolism. Sequence similarities, relative gene positions on the chromosome, and metabolic reconstruction (placement of gene products in metabolic pathways) were all used to aid gene assignments and for development of a functional overview. Amino acid biosynthesis was chosen to demonstrate the analytical capabilities of this approach. Only 10 expected enzymatic activities, of the nearly 150 involved in the biosynthesis of all 20 amino acids, are currently unassigned in the Thiobacillus genome. This result compares favorably with 10 missing genes for amino acid biosynthesis in the complete Escherichia coli genome. Gapped genome analysis can therefore give a decent picture of the central metabolism of a microorganism, equivalent to that of a complete sequence, at significantly lower cost.

Amino Acids↗
PubMed2000

Biphasic inotropic response to endothelin-1 in the presence of various concentrations of norepinephrine in dog ventricular myocardium.

The present study was undertaken to investigate the interaction between endothelin-1 (ET-1) and norepinephrine (NE) on contractile regulation in dog ventricular myocardium. ET-1 alone did not elicit any inotropic response in isolated dog ventricular trabeculae (37 degrees C, 0.5 Hz). In the presence of NE at a high concentration (10(-7) M), ET-1 (10(-8) M) elicited a long-lasting negative inotropic effect, while in the presence of NE at a moderate concentration (3 x 10(-8) M) it produced a biphasic inotropic effect: a sustained positive inotropic effect subsequent to a short-lasting negative inotropic effect. In the presence of a lower concentration (10(-9) M) that affected scarcely the basal force of contraction, ET-1 produced a pronounced positive inotropic effect in association with negative lusitropic and negative clinotropic effects in a concentration-dependent manner subsequent to a small transient negative inotropic effect. The presented results indicate that not only the extent, but also the quality of the inotropic response to ET-1 is determined by the level of NE in the biophase. The crosstalk of ET-1 with NE may play a crucial role in pathophysiological regulation of cardiac contractility in intact dog ventricular myocardium.

Animals↗
PubMed1999

Efficient and stable transduction of cardiomyocytes after intramyocardial injection or intracoronary perfusion with recombinant adeno-associated virus vectors.

BACKGROUND: The delivery of recombinant genes to cardiomyocytes holds promise for the treatment of a variety of cardiovascular diseases. Previous gene transfer approaches that used direct injection of plasmid DNA or replication-defective adenovirus vectors have been limited by low transduction frequencies and transient transgene expression due to immune responses, respectively. In this report, we have tested the feasibility of using intramyocardial injection or intracoronary infusions of recombinant adeno-associated virus (rAAV) vectors to program transgene expression in murine cardiomyocytes in vivo. METHODS AND RESULTS: We constructed an rAAV containing the LacZ gene under the transcriptional control of the cytomegalovirus (CMV) promoter (AAVCMV-LacZ). We then injected 1x10(8) infectious units (IU) of this virus into the left ventricular myocardium of adult CD-1 mice. Control hearts were injected with the AdCMV-LacZ adenovirus vector. Hearts harvested 2, 4, and 8 weeks after AAVCMV-LacZ injection demonstrated stable beta-galactosidase (beta-gal) expression in large numbers of cardiomyocytes without evidence of myocardial inflammation or myocyte necrosis. In contrast, the AdCMV-LacZ-injected hearts displayed transient beta-gal expression, which was undetectable by 4 weeks after injection. Explanted C57BL/6 mouse hearts were also perfused via the coronary arteries with 1.5x10(9) IU of AAVCMV-LacZ and assayed 2, 4, and 8 weeks later for beta-gal expression. beta-Gal expression was detected in <1% of cardiomyocytes at 2 weeks after perfusion but was detected in up to 50% of cardiomyocytes 4 to 8 weeks after perfusion. CONCLUSIONS: Direct intramyocardial injection or coronary artery perfusion with rAAV vectors can be used to program stable transgene expression in cardiomyocytes in vivo. rAAV appears to represent a useful vector for the delivery of therapeutic genes to the myocardium.

Animals↗
PubMed1999

Sulfhemoglobin formation in human erythrocytes by cystalysin, an L-cysteine desulfhydrase from Treponema denticola.

Cystalysin, isolated from the oral pathogen Treponema denticola, is an L-cysteine desulfhydrase (producing pyruvate, ammonia and hydrogen sulfide from cysteine) that can modify hemoglobin and has hemolytic activity. Here, we show that enzymatic activity of recombinant cystalysin depends upon stochiometric pyridoxal phosphate. The enzyme was not functional as an L-alanine transaminase, and had a strong preference for L-cysteine over D-cysteine. Cystalysin preferred small alpha-L-amino acids as substrates or inhibitors and was far more active towards L-cysteine than towards the other standard amino acids that undergo pyridoxal phosphate-dependent beta-elimination reactions (serine, threonine, tryptophan and tyrosine). Cystalysin tolerated small modifications to the carboxylate of L-cysteine (i.e., the methyl and ethyl esters of L-cysteine were good substrates), but the smallest possible peptide with an N-terminal cysteine, L-cysteinylglycine, was a very poor substrate. These results, combined with the implicit requirement for a free amine for pyridoxal phosphate-dependent reactions, imply that cystalysin cannot catabolize cysteine residues located within peptides. Cystalysin has Michaelis-Menten kinetics towards L-cysteine, and there was little or no inhibition by ammonia, H2S, pyruvate and acetate. Human erythrocytes incubated with H2S or with cystalysin and cysteine primarily accumulated sulfhemoglobin and methemoglobin, along with minor amounts of choleglobin and protein aggregates. Erythrocytes retained the ability to reduce methemoglobin in the presence of H2S. Cystalysin could not modify hemoglobin when beta-chloroalanine was the substrate, indicating an absolute requirement for H2S production. Cystalysin appears to be an unregulated L-cysteine catabolizing enzyme, with the resulting H2S production being essential to the atypical hemolytic activity.

Cystathionine gamma-Lyase↗
PubMed1999

Hemoxidation and binding of the 46-kDa cystalysin of Treponema denticola leads to a cysteine-dependent hemolysis of human erythrocytes.

Cystalysin, a 46-kDa protein isolated from the cytosol of Treponema denticola, was capable of both cysteine dependent hemoxidation and hemolysis of human and sheep red blood cells. The activities were characteristic of a cysteine desulfhydrase. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and Western immunoblotting analysis of the interaction of cystalysin with the red blood cells revealed an interaction of the protein with the red blood cell membrane. Substrates for the enzyme (including L-cysteine and beta-chloroalanine) enhanced the interaction, which occurred with both whole red blood cells as well as with isolated and purified red blood cell ghosts. SDS-PAGE and western immunoblotting employing anti-hemoglobin serum revealed that, during the hemoxidative events, the hemoglobin molecule associated with the red blood cell membrane, forming putative Heinz bodies. Spectrophotometric analysis of the hemoxidative events (cystalysin + cysteine + red blood cells) revealed a chemical modification of the native hemoglobin to sulfhemoglobin and methemoglobin. Hemoxidation also resulted in the degradation of both the red blood cell alpha- and beta-spectrin. The results presented suggest that the interaction of cystalysin with the red blood cell membrane results in the chemical oxidation of the hemoglobin molecule as well as an alteration in the red blood cell membrane itself.

Bacterial Proteins↗
PubMed1999

Cystalysin, a 46-kDa L-cysteine desulfhydrase from Treponema denticola: biochemical and biophysical characterization.

A 46-kDa hemolytic protein referred to as cystalysin, from Treponema denticola ATCC 35404, was characterized and overexpressed in Escherichia coli LC-67. Cystalysin lysed erythrocytes, hemoxidized hemoglobin to sulfhemoglobin and methemoglobin, and removed the sulfhydryl and amino group from selected S-containing compounds (e.g., cysteine) producing H2S, NH3, and pyruvate. With L-cysteine as substrate, cystalysin obeys Michaelis-Menten kinetics. Cystathionine and s-aminoethyl-L-cysteine were also substrates. Several of the small alpha amino acids were found to be competitive inhibitors of cystalysin. The enzymatic activity was increased by beta-mercaptoethanol and was not inhibited by the proteinase inhibitor TLCK (N alpha-p-tosyl-L-lysine chloromethyl ketone), pronase, or proteinase K, suggesting the functional site was physically protected or located in a small fragment of the polypeptide. We hypothesize that cystalysin is a pyridoxal-5-phosphate-containing enzyme with the activity of an alphaC-N and betaC-S lyase (cystathionase). Since high amounts of H2S have been reported in deep periodontal pockets, this metabolic enzyme from T. denticola may also function in vivo as an important virulence molecule.

Cystathionine gamma-Lyase↗
PubMed1999

An audit of measuring equipment in elderly care.

Accurate monitoring of weight and height is a vital element of nutritional assessment. Specialist equipment may be required for older patients. Accuracy depends upon calibration and maintenance of equipment.

Aged↗
PubMed1999

Genetic alterations in ERBB2-amplified breast carcinomas.

Amplification of the ERBB2 oncogene has recently received attention as a target for antibody-based therapies and as a predictor of response to adjuvant chemotherapy. Modification of treatment strategies based on ERBB2 status has led to further interest in the genetic alterations that accompany ERBB2 gene amplification or overexpression. In this study, chromosome alterations that are associated with ERBB2 amplification were defined by comparative genomic hybridization (CGH). Additionally, fluorescence in situ hybridization (FISH) was used to validate gene amplification, and protein expression was detected immunohistochemically. ERBB2-amplified tumors as detected by FISH, immunohistochemistry (IHC), or CGH had twice as many CGH-defined chromosomal alterations (means of 11.8, 11.0, and 12.7, respectively) as the nonamplified tumors (means of 6.8, 7.0, and 5.6, respectively). ERBB2 positivity correlated with the total number of genetic events. A wide spectrum of copy number gains and losses was seen by CGH in all of the tumors. An increased number of losses of 18q and gains of 20q was found in ERBB2-positive tumors. Other common aberrations for all of the tumors were copy number gains of 1q (58%), 8q (52%), 20q (30%), and losses of 18q (39%), 13q (39%), and 3p (33%). A high degree of concordance was observed among the three methods in 33 primary breast cancers. The concurrence for ERBB2 detection between FISH and IHC was 90%, between FISH and CGH was 82%, and between IHC and CGH was 84%. This study shows that breast tumors showing erbB2 overexpression or gene amplification are genetically distinct from erbB2-negative tumors. These differences may relate to the mechanisms underlying altered response to adjuvant therapies and may define the responsiveness to erbB2-directed immunotherapy.

Breast Neoplasms↗
PubMed1999

[Experimental studies on improving heart preservation effect of Astragalus saponins].

OBJECTIVE: To observe the effect of heart preservation of Astragalus saponins (AS) in modified Euro-Collins solution (mEC) containing AS. METHODS: Wistar rats were randomly divided into mEC and AS group. After preserving isolated rat hearts 6 hours by simple cold storage with mEC and mEC containing AS respectively, Langendorff's isolated rat heart model was used to reperfuse for 30 minutes to study cardiac function after preservation and the effect of preventing oxygen free radical injury. RESULTS: To compare AS group with mEC group, cardiac function and coronary flow of the hearts after preservation were better than mEC group (P < 0.05), in AS group the water content of myocardium was decreased very significantly (P < 0.01), myocardial lactate dehydrogenase and creatine phosphokinase release were reduced greatly (P < 0.05 and P < 0.01), myocardial superoxide dismutase activity was increased very significantly (P < 0.01) and the content of lipid peroxide was decreased significantly (P < 0.05). CONCLUSION: AS could improve the effect of heart preservation of mEC solution, its mechanism might be associated with the effect of negative contractile strength and preventing oxygen free radical injury.

Animals↗
PubMed1999

[Determination of K, Na and Ca in alizarin by flame atomic absorption spectrophotometry].

This paper reports the development of the determination of trace metals K, Na and Ca in alizarin. The method is convenient to determine elements in alizarin by flame atom absorption spectrophotometry. The results show that the method has good precision and accuracy. The relative standard deviations of K, Na and Ca are 4.4%, 2.5% and 3.7%, respectively, and the rates of recovery are 97.5%, 98.3% and 98.1% respectively.

English Abstract↗
PubMed1998

Complications of axillary lymph node dissection for carcinoma of the breast: a report based on a patient survey.

BACKGROUND: Axillary lymph node dissection is commonly performed as part of the primary management of breast carcinoma. Its value in patient management, however, has recently been questioned. Few studies exist that document long term complications. METHODS: Four hundred thirty-two patients with Stage I or II breast carcinoma who were free of recurrence 2-5 years after surgery were identified. A cross-sectional survey was conducted to determine the prevalence of long term symptoms and complications as perceived by the patient, and patient and treatment factors that may have predicted complications were determined. Three hundred thirty of the 432 (76%) completed a mailed, self-administered questionnaire. In addition, the medical records of the 330 patients were reviewed. Patient and treatment factors were analyzed with logistic regression. RESULTS: Numbness was reported by 35% of patients at the time of the survey. Pain was noted in 30%, arm swelling in 15%, and limitation of arm movement in 8%. Eight percent reported episodes of infection or inflammation at some point since the diagnosis of breast carcinoma. The majority of symptoms were mild and interfered minimally with daily activities. Younger age (P=0.001) was associated with more frequent reporting of pain. Numbness was more common in younger patients (P=0.004) as well as in those with a history of smoking (P=0.012). There was a positive association of limitation of arm motion with adjuvant tamoxifen therapy (P=0.016). Arm swelling was associated with both younger age (P=0.004) and greater body surface area (P=0.008). Radiation therapy was associated with a higher frequency of infection or inflammation in the arm and/or breast (P=0.001). CONCLUSIONS: Mild symptoms, especially pain and numbness, are common 2-5 years after axillary lymph node dissection. The frequency of inflammation or infection in patients treated with radiation to the breast or chest wall after an axillary lymph node dissection may be greater than previously appreciated. Severe complications or symptoms that have a major impact on daily activities are uncommon. These findings should help health care providers and their patients with breast carcinoma weigh the pros and cons of axillary lymph node dissection.

Activities of Daily Living↗