Biomedical subjects

H Y Lin

Publications and source records attributed to H Y Lin.

At least 37 records · Page 2Linked to original sources

PubMed2001

Functions of the conserved anionic amino acids and those interacting with the substrate phosphate group of phosphoglucose isomerase.

Phosphoglucose isomerase catalyzes the isomerization between glucose 6-phosphate and fructose 6-phosphate in cytoplasm, and functions as autocrine motility factor and neuroleukin outside the cells. A phosphoglucose isomerase from Bacillus stearothermophilus (pgiA) was subjected to mutagenesis study to address the catalytic function of the conserved anionic residues and those probably interacting with the phosphate group of substrates. The results suggest that Glu290 works concertedly with His311 as a general acid-base pair to initiate the isomerization step, and Glu150 assists the base function of His311. The conserved loop structure consisting of Gly205-Gly206-Arg207 plays a critical role for the recognition of substrates.

Amino Acid Substitution↗

PubMed2001

Determination of the maximum specific uptake capacities for glucose and oxygen in glucose-limited fed-batch cultivations of Escherichia coli.

A simple pulse-based method for the determination of the maximum uptake capacities for glucose and oxygen in glucose limited cultivations of E. coli is presented. The method does not depend on the time-consuming analysis of glucose or acetate, and therefore can be used to control the feed rate in glucose limited cultivations, such as fed-batch processes. The application of this method in fed-batch processes of E. coli showed that the uptake capacity for neither glucose nor oxygen is a constant parameter, as often is assumed in fed-batch models. The glucose uptake capacity decreased significantly when the specific growth rate decreased below 0.15 h(-1) and fell to about 0.6 mmol g(-1) h(-1) (mmol per g cell dry weight and hour) at the end of fed-batch fermentations, where specific growth rate was approximately 0.02 h(-1). The oxygen uptake capacity started to decrease somewhat earlier when specific growth rate declined below 0.25 h(-1) and was 5 mmol g(-1) h(-1) at the end of the fermentations. The behavior of both uptake systems is integrated in a dynamic model which allows a better fitting of experimental values for glucose in fed-batch processes in comparison to generally used unstructured kinetic models.

Culture Media↗

PubMed2001

Thyroid hormone promotes serine phosphorylation of p53 by mitogen-activated protein kinase.

L-Thyroxine (T(4)) nongenomically promotes association of mitogen-activated protein kinase (MAPK) and thyroid hormone receptor TRbeta1 (TR) in the cell nucleus, leading to serine phosphorylation of the receptor. The oncogene suppressor protein, p53, is serine phosphorylated by several kinases and is known to interact with TRbeta1. We studied whether association of p53 and TR is modulated by T(4) and involves serine phosphorylation of p53 by MAPK. TR-replete 293T human kidney cells were incubated with a physiological concentration of T(4) for 10-90 min. Nuclear fractions were immunoprecipitated and the resulting proteins separated and immunoblotted for co-immunoprecipitated proteins. Activated MAPK immunoprecipitates of nuclei from T(4)-treated cells accumulated p53 in a time-dependent manner; T(4) and T(4)-agarose were more effective than T(3). T(4)-induced nuclear complexing of p53 and MAPK was inhibited by PD 98059 (PD) and U0126, two MAPK kinase (MEK) inhibitors, and was absent in cells treated with MEK antisense oligonucleotide and in dominant negative Ras cells. T(4) also caused nuclear co-immunoprecipitation of TRbeta1 and p53, an effect also inhibited by PD. Nuclear complexing of p53 and MAPK also occurred in HeLa cells, which lack functional TR. Constitutively activated MAPK caused phosphorylation of a recombinant p53-GST fusion protein in vitro; thus, p53 is a substrate for MAPK. An indicator of p53 transcriptional activity, accumulation of the immediate-early gene product, c-Jun, was inhibited by T(4). This T(4) effect was reversed by PD, indicating that the transcriptional activity of p53 was altered by T(4)-directed MAPK-p53 interaction.

3T3 Cells↗

PubMed2001

Physiological responses to mixing in large scale bioreactors.

Escherichia coli fed-batch cultivations at 22 m3 scale were compared to corresponding laboratory scale processes and cultivations using a scale-down reactor furnished with a high-glucose concentration zone to mimic the conditions in a feed zone of the large bioreactor. Formate accumulated in the large reactor, indicating the existence of oxygen limitation zones. It is suggested that the reduced biomass yield at large scale partly is due to repeated production/re-assimilation of acetate from overflow metabolism and mixed acid fermentation products due to local moving zones with oxygen limitation. The conditions that generated mixed-acid fermentation in the scale-down reactor also induced a number of stress responses, monitored by analysis of mRNA of selected stress induced genes. The stress responses were relaxed when the cells returned to the substrate limited and oxygen sufficient compartment of the reactor. Corresponding analysis in the large reactor showed that the concentration of mRNA of four stress induced genes was lowest at the sampling port most distant from the feed zone. It is assumed that repeated induction/relaxation of stress responses in a large bioreactor may contribute to altered physiological properties of the cells grown in large-scale bioreactor. Flow cytometric analysis revealed reduced damage with respect to cytoplasmic membrane potential and integrity in cells grown in the dynamic environments of the large scale reactor and the scale-down reactor.

Acetic Acid↗

PubMed2001

The dilemma of "to-be or not-to-be": needs and expectations of the Taiwanese cadaveric organ donor families during the pre-donation transition.

There has been little study of the Chinese cadaveric donor family's decisions to donate organs within the Chinese cultural framework. A convenience sample of 25 cadaveric donor family members (12 men, 13 women) who gave their consent to donation at National Taiwan University Hospital agreed to participate in this study and completed in-depth interviews. Data were analyzed by a three-steps within-method qualitative triangulation method. The factors influencing the donor family's decisions to donate organs, the needs of donor families, and their expectations of health care providers during the pre-donation transition--the critical period of time between signing a donation and consent to organ harvesting--were examined. The background context and a conceptual framework were further developed to discuss and depict this phenomenon. This project aims to broaden the horizon on organ donation and contribute to the understanding of some of the psychodynamic issues in the Chinese family in Taiwan.

Adult↗

PubMed2001

Computer-aided prototype system for nose surgery.

Rhinoplasty, or surgery to reshape the nose, is one of the most common of all plastic-surgery procedures. Rhinoplasty can enhance a patient's appearance and self-confidence, may also correct a birth defect or injury, or help relieve some breathing problem. In this paper, we present a three-dimensional (3-D) surgical simulation system, which can assist surgeons in planning rhinoplasty procedures. This system employs computer graphics and image-processing techniques for the simulation of a rhinoplasty. Although the presented algorithms themselves are not new, the proposed system exploits the new idea to apply 3-D morphing for rhinoplasty, and simulation results are useful for the physicians. According to patients' expectation of what they would like their noses to look like, our system simulates expected results. Our tools provide quantitative measurements of a nose structure. Using these quantitative results, surgeons can arrange appropriate preoperative plans for patients. Finally, experimental results and experiences are reported to evaluate the usefulness of the proposed system.

Computer Simulation↗

PubMed2001

Gender differences in the relationships of serum uric acid with fasting serum insulin and plasma glucose in patients without diabetes.

OBJECTIVE: To explore gender differences in the relationship of serum uric acid levels with fasting serum insulin and fasting plasma glucose concentrations among an adult Chinese nondiabetic population in Kinmen, Taiwan. METHODS: A total of 7,483 nondiabetic subjects (4,265 women, 3,218 men, aged 30 to 89 years) were involved in a community based epidemiologic study. Those with known or newly diagnosed diabetes were excluded. Overnight fasting blood samples were drawn for serum uric acid, glucose, insulin, lipid, and other biochemical measurements. Demographic and clinical variables including body mass index (weight/height2), waist-to-hip ratio, and blood pressure were measured and documented during face-to-face interviews with structured questionnaires. RESULTS: Stratified analyses revealed that (1) serum uric acid levels were positively associated with hyperinsulinemia and HOMA-insulin resistance in both men and women after adjusting for hypertriglyceridemia, hypertension, obesity, and plasma glucose levels; and (2) serum uric acid levels were more strongly associated with hyperinsulinemia and plasma glucose levels in women than in men. CONCLUSION; Hyperuricemia was positively associated with hyperinsulinemia among patients of both sexes without diabetes. Elevated levels of uric acid should alert physicians to the possibility of insulin resistance. The serum uric acid level was associated with insulin resistance and plasma glucose levels more strongly in females than in males in our study population.

Adult↗

PubMed2001

Cystitis glandularis mimics bladder cancer--three case reports and literature review.

Cystitis glandularis is an uncommon proliferative disorder of the mucus-producing glands within the mucosa and submucosa of urinary bladder epithelium. We report three cases with gross hematuria on first presentation. Both sonography and computer tomography revealing bladder tumor and transurethral resection was performed in all three cases. Cystitis glandularis was confirmed by pathology. Short-term follow-up of sonography and cystoscopy showed good results.

Adult↗

PubMed2001

Steroid allergy: report of two cases.

Corticosteroid preparations have anti-inflammatory and immunosuppressive properties and are widely used in the treatment of asthma and allergic disorders. Steroids themselves, however, can induce hypersensitivity reactions. The number of reports on contact allergy or anaphylactic reactions is increasing. Steroid hypersensitivity should be considered in any patient whose dermatitis becomes worse with topical steroid therapy, or in patients who develop systemic allergic reactions after the use of systemic steroids. The diagnosis can be confirmed by skin testing, in vitro evidence of specific IgE, oral or parenteral challenge, or an allergic patch test. The latter may be positive within 20 min, which indicates immediate contact urticaria, or at 72 to 96 h, which indicates delayed contact hypersensitivity. In this article we report two cases of steroid allergy. Case 1 was a 5-year-old asthmatic boy with an anaphylactic reaction to steroids and aspirin. Case 2 was a 2-year-old boy with atopic dermatitis and steroid contact urticaria. Both cases 1 and 2 showed positive results to triamcinolone, dexamethasone, hydrocortisone, and methylprednisolone in the immediate skin allergy test. Case 2 had immediate contact urticaria to hydrocortisone and clobetasone butyrate. Case 1 had a positive systemic allergic reaction to cortisone acetate, prednisolone, and dexamethasone on the oral steroid challenge test, and also had aspirin induced angioedema and urticaria 10 min after challenge with 50 mg aspirin.

Adrenal Cortex Hormones↗

PubMed2001

Tentative surgical repair of leaking filtering bleb with amniotic membrane transplantation--a case report.

To repair a traumatic leaking cystic bleb in a 50-year-old male patient who had received multiple glaucoma filtering surgeries with the application of mitomycin-C, an amniotic membrane covered over the leaking bleb and sutured it to the adjacent conjunctiva with 10-0 nylon was done. The anterior chamber gradually formed after the amniotic membrane transplantation (AMT) and intraocular pressure returned to the level before trauma. Three weeks after the operation, the amniotic membrane was removed. No more leakage from the bleb was observed during four months follow-up. However, another bleb revision surgery was performed later to repair recurrent bleb leakage. Although conjunctival advancement or free conjunctival autograft have been reported to repair leaking bleb successfully, the simple primary method of using AMT is still encouraged in repair of a ruptured bleb with tentative maintenance of adequate filtration.

Amnion↗

PubMed2001

Comparison of hand-assisted laparoscopic nephroureterectomy with open surgery for upper urinary tract tumor.

Herein we report on our initial experience in performing nephroureterectomy by hand-assisted laparoscopic surgery, and compare the results with those performed by traditional open methods. From December 2000 to September 2001, 10 patients with upper urinary tract tumors underwent hand-assisted laparoscopic nephroureterectomy. Except for one patient who required elective conversion to open surgery due to renal vein injury, this cohort of 9 patients was compared to a group of 35 patients who had received traditional open nephroureterectomy over the last 2 years. Demographic, intraoperative and postoperative data were compared retrospectively. These two groups were similar in age, body mass index, operation time and time to postoperative oral intake. However, the hand-assisted laparoscopy group was found to have significantly less blood loss, less need for parenteral narcotic and a shorter length of time needed for postoperative hospitalization than the open group. Thus, in this report we have demonstrated hand-assisted laparoscopic nephroureterectomy to be a safe and efficacious treatment of malignant urinary collecting tumors. We believe the benefits of this minimally invasive surgery make it a viable alternative technique for management of upper urinary tract tumor.

Adult↗

PubMed2001

[Contents of total flavonoids in Rhizoma Arisaematis].

OBJECTIVE: Comparing the contents of total flavonoides of Rhizoma Arisaematis, which collected in different time, regions, different varieties and processed. METHOD: Determining the contents by ultraviolet spectro-photometry. RESULT AND CONCLUSION: The contents were found in the following sequence: 1. the end of July, the begin of July, August, September; 2. Beijing, Shanxi, Sichuan, Anhui; 3. Arisaema erubenscens, A. heterophyllum, A. amurense; 4. unprocessed product, processed product.

Arisaema↗

PubMed2000

Thyroxine promotes association of mitogen-activated protein kinase and nuclear thyroid hormone receptor (TR) and causes serine phosphorylation of TR.

Activated nongenomically by l-thyroxine (T(4)), mitogen-activated protein kinase (MAPK) complexed in 10-20 min with endogenous nuclear thyroid hormone receptor (TRbeta1 or TR) in nuclear fractions of 293T cells, resulting in serine phosphorylation of TR. Treatment of cells with the MAPK kinase inhibitor, PD 98059, prevented both T(4)-induced nuclear MAPK-TR co-immunoprecipitation and serine phosphorylation of TR. T(4) treatment caused dissociation of TR and SMRT (silencing mediator of retinoid and thyroid hormone receptor), an effect also inhibited by PD 98059 and presumptively a result of association of nuclear MAPK with TR. Transfection into CV-1 cells of TR gene constructs in which one or both zinc fingers in the TR DNA-binding domain were replaced with those from the glucocorticoid receptor localized the site of TR phosphorylation by T(4)-activated MAPK to a serine in the second zinc finger of the TR DNA-binding domain. In an in vitro cell- and hormone-free system, purified activated MAPK phosphorylated recombinant human TRbeta1 (). Thus, T(4) activates MAPK and causes MAPK-mediated serine phosphorylation of TRbeta1 and dissociation of TR and the co-repressor SMRT.

Cell Line↗

PubMed2000

Fibroblast growth factor receptor 3 induces gene expression primarily through Ras-independent signal transduction pathways.

Fibroblast growth factor receptors (FGFR) are widely expressed in many tissues and cell types, and the temporal expression of these receptors and their ligands play important roles in the control of development. There are four FGFR family members, FGFR-1-4, and understanding the ability of these receptors to transduce signals is central to understanding how they function in controlling differentiation and development. We have utilized signal transduction by FGF-1 in PC12 cells to compare the ability of FGFR-1 and FGFR-3 to elicit the neuronal phenotype. In PC12 cells FGFR-1 is much more potent in the induction of neurite outgrowth than FGFR-3. This correlated with the ability of FGFR-1 to induce robust and sustained activation of the Ras-dependent mitogen-activated protein kinase pathways. In contrast, FGFR-3 could not induce strong sustained Ras-dependent signals. In this study, we analyzed the ability of FGFR-3 to induce the expression of sodium channels, peripherin, and Thy-1 in PC12 cells because all three of these proteins are known to be induced via Ras-independent pathways. We determined that FGFR-3 was capable of inducing several Ras-independent gene expression pathways important to the neuronal phenotype to a level equivalent of that induced by FGFR-1. Thus, FGFR-3 elicits phenotypic changes primarily though activation of Ras-independent pathways in the absence of robust Ras-dependent signals.

Animals↗

PubMed2000

Monitoring of genes that respond to overproduction of an insoluble recombinant protein in Escherichia coli glucose-limited fed-batch fermentations.

The cellular response of Escherichia coli to overproduction of the insoluble heterologous protein alpha-glucosidase of Saccharomyces cerevisiae during a glucose-limited fed-batch fermentation was analyzed on the transcriptional and the translational levels. After the induction of the tac-regulated overexpression of the recombinant model protein, a significant but transient increase of the mRNA levels of the heat shock genes lon and dnaK could be observed. The mRNA level of the gene coding for the inclusion body-associated protein IbpB showed the strongest increase and remained at a clearly higher level until the end of the fermentation. By contrast, the mRNA levels of htrA and ppiB were decreased after induction of the alpha-glucosidase overexpression. Analysis of the soluble cytoplasmic protein fraction 3 h after induction revealed increased levels of the chaperones GroEL, DnaK, and Tig and a decrease in the protein levels of the two ribosomal proteins S6 and L9, the peptidylprolyl-cis-trans-isomerase PpiB, and the sigma(38)-dependent protein Dps. Analysis of the aggregated protein fraction revealed a remarkably inhomogeneous composition of the alpha-glucosidase inclusion bodies. N-terminal sequencing and MALDI-TOF mass spectrometry identification showed that most of these spots are fragments of the heterologous alpha-glucosidase. Host stress proteins, like DnaK, GroEL, IbpA, IbpB, and OmpT, have been found to be associated with the alpha-glucosidase protein aggregates.

Biotechnology↗

PubMed2000

Influence of controlled glucose oscillations on a fed-batch process of recombinant Escherichia coli.

The influence of glucose oscillations on cell growth and product formation of a recombinant Escherichia coli culture producing a heterologous alpha-glucosidase was studied in fed-batch cultures in a laboratory bioreactor. Glucose oscillations were created by an on/off-feeding mode in either fast cycles (1 min) or slow cycles (4 min) and compared to a process with constant glucose addition. The study indicates that glucose oscillations influence the product stability and the overgrowth of plasmid-free cells if such cultures are not performed under continuous pressure for selection of plasmid-containing cells. Although the glucose uptake capacity decreased after induction of the recombinant alpha-glucosidase in all cultures performed, the up-growth of plasmid-free cells during the production phase was strongly inhibited by fast oscillations. In contrast, plasmid-free cells grew up when constant feeding or slow cycles were applied. Our data suggest that the various feed protocols effect the specific carbon dioxide formation rate differently, with the highest production of carbon dioxide in the cultivations with fast cycles. In connection to product formation the initial alpha-glucosidase accumulation was the same in all cultures, but the stability of the product was significantly lower in the cultivation with slow cycles. Our results from laboratory experiments are discussed in relation to the mixing situation in large-scale bioreactors.

Bioreactors↗

PubMed2000

Negative fast atom bombardment ionization of aromatic sulfonic acids: unusual sample-matrix interaction.

The most intense ion(s) in negative ion fast atom bombardment (FAB) mass spectra of 2- and 4-benzaldehyde sulfonic acid (BSA) in glycerol or 3-nitrobenzyl alcohol matrix corresponds to a covalent association of the analyte with one or two matrix molecules accompanied by the elimination of a molecule of water. The molecular ion [M - H](-), however, is of low abundance. The identity of the resulting ions [M + nA - H(2)O - H](-) (where M is the analyte and A is the matrix) was confirmed by exact mass measurement using the peak matching technique. These covalent matrix-analyte complexes were not observed when the sulfonic acid functionality in BSA was substituted with COOH, NO(2), and OH or when the sulfonic acid was in salt form. These observations indicate that the free sulfonic acid group in BSA is responsible for the covalent adduct formation. To our knowledge, analyte-matrix covalent association in negative ion FAB spectra of BSA has not been reported previously.

Benzaldehydes↗

PubMed2000

Differential induction of tumor necrosis factor alpha and manganese superoxide dismutase by endotoxin in human monocytes: role of protein tyrosine kinase, mitogen-activated protein kinase, and nuclear factor kappaB.

A mutant Escherichia coli lipopolysaccharide (LPS) lacking myristoyl fatty acid markedly stimulates the activity of manganese superoxide dismutase (MnSOD) without inducing tumor necrosis factor alpha (TNFalpha) production by human monocytes (Tian et al., 1998, Am J Physiol 275:C740.), suggesting that induction of MnSOD and TNFalpha by LPS are regulated through different signal transduction pathways. The protein tyrosine kinase (PTK)/mitogen-activated protein kinase (MAPK) pathway plays an important role in the LPS-induced TNFalpha production. In the current study, we determined the effects of PTK inhibitors, genistein and herbimycin A, on the induction of MnSOD and TNFalpha in human monocytes. Genistein (10 microg/ml) and herbimycin A (1 microg/ml) markedly inhibited LPS-induced protein tyrosine phosphorylation, phosphorylation and nuclear translocation of MAPK (p42 ERK, extracellular signal-regulated kinase), and increases in the steady state level of TNFalpha mRNA as well as TNFalpha production. In contrast, at similar concentrations, genistein and herbimycin A had no effect on the LPS-induced activation of nuclear factor kappaB (NFkappaB) and induction of MnSOD (mRNA and enzyme activity) in human monocytes. In addition, inhibition of NFkappaB activation by gliotoxin and pyrrodiline dithiocarbamate, inhibited LPS induction of TNFalpha and MnSOD mRNAs. These results suggest that (1) while PTK and MAPK are essential for the production of TNFalpha, they are not necessary for the induction of MnSOD by LPS, and (2) while activation of NFkappaB alone is insufficient for the induction of TNFalpha mRNA by LPS, it is necessary for the induction of TNFalpha as well as MnSOD mRNAs.

Benzoquinones↗