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Biomedical subjects

S H Lin

Publications and source records attributed to S H Lin.

At least 181 records · Page 10Linked to original sources
PubMed1994

Starburst dendrimers: enhanced performance and flexibility for immunoassays.

Starburst dendrimers are novel, water-soluble polymeric materials, with a well-defined composition and structure. In our application, we used dendrimers composed of poly(amidoamine) groups to which we coupled several specific antibodies, to investigate potential formats based on radial partition immunoassay. The coupled antibodies have retained their stability and immunological binding after coupling, both in solution and when immobilized onto a solid support. On the basis of our feasibility studies with model systems, we conclude that immunoassays can be developed with performance equivalent to or better than that in many established systems. By application of a mixture of the dendrimer-coupled antibody and the analyte of interest to the solid phase, we have investigated the performance characteristics of solution-phase immunoassays. Our experiments demonstrate enhanced sensitivity for creatine kinase MB isoenzyme (CKMB), thyrotropin, and myoglobin assays and reduced instrumental analysis time for the CKMB assay.

Creatine Kinase↗
PubMed1993

Time resolution of fluorescence changes observed in titrations of fluorescein 5'-isothiocyanate-modified Na,K-ATPase with monovalent cations.

Equilibrium fluorometric titrations of fluorescein 5'-isothiocyanate-modified Na,K-ATPase with cations have usually been interpreted by assuming that an enhancement reports the conformational change from E2 to E1. We report time resolution of the fluorescence change into three phases when fluorophore-modified enzyme is mixed with the chloride salt of either sodium or choline in a stopped-flow instrument. The first phase is an increase in fluorescence within the dead time of the instrument that is also observed when fluorescein 5'-isothiocyanate (FITC) reacted with lysine is substituted for fluorescein-labeled enzyme. The other two phases occur on millisecond and second time scales. Three phases are also observed when fluorophore-modified enzyme preincubated in KCl is mixed with NaCl, but in this case the slowest phase is absent when choline chloride replaces NaCl. The two faster effects in phases one and two can be eliminated either by controlling the ionic strength or by anti-fluorescein antibody. Labeling the enzyme with fluorescein 5'-isothiocyanate in the presence of its substrate, adenosine 5'-triphosphate, practically eliminates the slowest effect. These results demonstrate that fluorescein reports three events that occur on three different time scales. The fastest phase reports the ionic strength jump of unbound fluorophore. The intermediate phase reports the ionic strength jump of fluorescein at "antibody-accessible" sites [Abbott, A. J., Amler, E., & Ball, W. J., Jr. (1991) Biochemistry 30, 1692-1701]. Only the slowest phase reports the enzyme conformational change implicated in transport.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Rearrangement of bcl-2 genes in malignant lymphomas in Chinese patients.

BACKGROUND: Only a small percentage of Asian patients with non-Hodgkin lymphoma may have follicular type disease. According to molecular analysis done recently, the incidence of rearrangement of bcl-2 gene in patients with follicular lymphoma was lower in Japan than in the United States, suggesting possible geographic or racial differences between Asian and Western populations. The current study was undertaken to obtain data from Taiwan to compare with data from Japan, Hong Kong, and Western countries. METHODS: Using probes of genomic 5' bcl-2, major breakpoint region (mbr) and minor breakpoint cluster region (mcr) for the breakpoint cluster region of the bcl-2 gene, genomic DNA samples from 55 patients with B-cell lymphoma (17 with follicular type and 38 with diffuse type) were analyzed by Southern blot analysis. RESULTS: Eleven patients had bcl-2 gene rearrangement, including 9 of 17 (52.9%) patients with follicular lymphoma and 2 of 38 (5.3%) patients with diffuse B-cell lymphoma. Nine patients had the breakpoint located within the mbr, one at both the mbr and the 5' bcl-2 regions, and the other had bcl-2 translocation with involvement of the mcr. DNA fragment of bcl-2 was found to comigrate with JH genes in all patients with follicular lymphoma and diffuse lymphoma who had bcl-2 rearrangement at mbr. The remaining patient who had bcl-2 translocation at mcr had no comigration with JH, Jk, or C lambda genes. CONCLUSIONS: Despite the low incidence of follicular lymphoma in Chinese patients, the incidence of bcl-2 gene involvement was higher in patients from Taiwan than in those from Japan and Hong Kong, but similar to the incidence of those from Western countries.

Adolescent↗
PubMed1993

Structure and function of C-CAM1. The first immunoglobulin domain is required for intercellular adhesion.

Cell-CAM105 proteins (also called C-CAM) are epithelial cell adhesion molecules of the immunoglobulin (Ig) superfamily. The sequences of C-CAM are highly homologous to those of human carcinoembryonic antigen (CEA)-family proteins. In previous studies using baculoviral vectors, we showed that expression of the L-form cell-CAM105 (also called C-CAM1) in insect cells resulted in cell aggregation (Cheung, P. H., Thompson, N. L., Earley, K., Culic, O., Hixson, D., and Lin, S. H. (1993) J. Biol. Chem. 268, 6139-6146). This result indicates that the insect-cell system is suitable for studying the adhesion function of C-CAM. Since C-CAM1 contains four extracellular Ig-domains, the structural features directly responsible for C-CAM1 adhesion function were investigated by site-directed deletion and expression in the baculovirus/insect cell system. Results from these studies indicated that the first Ig domain located in the NH2-terminal of C-CAM plays a crucial role in intercellular adhesion. Site-directed deletion producing mutants lacking the second, third, or fourth Ig domains had no effect on the adhesion function. In addition, adhesion function was retained when both the third and fourth Ig domains were deleted, although the adhesion activity was reduced to half that in control cells. However, simultaneous deletion of the second, third, and fourth domains abolished adhesion, suggesting that these domains affect the accessibility of the binding site localized in the first domain. In our previous studies, we showed that the cytoplasmic domains of C-CAM play a significant role in the isoforms' adhesion activity since expression of a C-CAM isoform containing only 6 instead of 71 amino acids intracellularly failed to show the adhesion phenotype (Cheung, P. H., Culic, O., Qiu, Y., Earley, K., Thompson, N., Hixson, D. C., and Lin, S.-H. (1993) Biochem. J. 295, in press). These results together suggest that both the cytoplasmic domain and the first N-terminal Ig-like domain are required for C-CAM-mediated cell adhesion activity.

Adenosine Triphosphatases↗
PubMed1993

The cytoplasmic domain of C-CAM is required for C-CAM-mediated adhesion function: studies of a C-CAM transcript containing an unspliced intron.

Cell-CAM105 (also named C-CAM) is a cell surface glycoprotein involved in intercellular adhesion of rat hepatocytes. It has four extracellular immunoglobulin (Ig) domains, a transmembrane domain and a cytoplasmic domain and therefore is a member of the Ig supergene family. We have characterized multiple cDNAs of the C-CAM genes in rat intestine. Sequence analyses showed that rat intestine contained not only the previously reported L-form and S-form C-CAMs (renamed C-CAM1 and C-CAM2 respectively) but also a new isoform, C-CAM3. The C-CAM3 transcript codes for a polypeptide with a truncated C-terminus that lacks 65 amino acids from the previously reported C-CAM1 cytoplasmic domain. Unlike C-CAM1, C-CAM3 did not mediate cell adhesion when expressed in insect cells using the baculoviral expression system. Thus the extra 65 amino acids in the cytoplasmic domain of C-CAM1 are important for adhesion phenotype when expressed in insect cells. Although C-CAM1 and C-CAM2 are encoded by different genes, sequence analysis suggests that C-CAM3 is probably derived from alternative splicing of the C-CAM1 gene. To examine this possibility, we have determined the exon organization of the C-CAM1 gene. C-CAM3 differed from C-CAM1 by the presence of a single unspliced intron which contained a stop codon immediately after the regular splice junction. As a result, translation of C-CAM3 terminates at the point where C-CAM1 and C-CAM3 sequences diverge. To investigate the expression of C-CAM1, C-CAM2 and C-CAM3 in different tissues, we used an RNAase-protection assay to simultaneously assess the levels of expression of these transcripts. Using total RNA prepared from various tissues, we showed that expression of C-CAM3 was tissue-specific, and the C-CAM3 transcript accounted for about 25% of the transcripts derived from the C-CAM1 gene. However, further analysis revealed that C-CAM3 transcript was not present in cytosolic RNA, rather it was enriched in nuclear RNA prepared from hepatocytes. Although C-CAM3 cDNA contains the polyadenylation signal and is polyadenylated, these results indicate that C-CAM3 is probably an incomplete spliced product of C-CAM1 gene.

Adenosine Triphosphatases↗
PubMed1993

Cell-CAM105 isoforms with different adhesion functions are coexpressed in adult rat tissues and during liver development.

The rat hepatocyte cell adhesion molecule cell-CAM105 has recently been shown to be composed of at least two isoforms. Expression of the two isoforms in different tissues and during fetal liver development in rats was studied by RNase protection using a probe which could specifically and simultaneously detect both isoforms. This probe revealed protected fragments of expected lengths for the L-form and the S-form in RNA samples isolated from various adult rat tissues. High levels of the L-form and S-form messages were detected in liver and intestine, moderate levels were detected in lung, and weak signals were detected in muscle, kidney, and spleen. In liver development studies, the messages for cell-CAM105 showed a major increase on the first day after birth compared to the fetal stage, and both isoform messages were proportionally increased. These results indicate that both cell-CAM105 isoforms may have function(s) related to hepatocyte differentiation. To study the adhesion function of cell-CAM105 isoforms, full-length cDNAs for these isoforms were expressed in insect cells. The insect cells expressing the L-form cell-CAM105 were found to aggregate. However, expression of S-form cell-CAM105 did not support cell aggregation. These results indicate that L-form, but not S-form, cell-CAM105 directly mediates the cell adhesion function.

Adenosine Triphosphatases↗
PubMed1993

Clinical and pathological studies on peripheral neuropathy of six Chinese patients with lung cancer: morphometric evaluation of the sural nerve on biopsy.

We attempted to elucidate the nature of the nerve fiber degeneration and clinical features of six Chinese patients with lung cancer preceded by sensory disturbances, with special emphasis put on the morphometric analysis of the nerve fibers of the sural nerve obtained on biopsy. The patients were all male and ranged from thirty-nine to sixty-seven years of age on admission. They all complained of paresthesia as the initial symptom in the distal portion of both extremities, two to seventy-two months prior to the diagnosis of the cancer. The paresthesia was slowly progressive and mild to moderate in severity without obvious subjective sensory loss. Four patients showed diminished Achilles reflex and decreased vibration sensation at the lateral malleolus. Morphometric evaluation of the sural nerve revealed that the loss of myelinated and unmyelinated fibers was not frequent and the increase in the density of the small myelinated fibers was prominent, suggesting the presence of axonal atrophy. Therefore, it was concluded that the histologic findings of our patients are different from those found in subacute carcinomatous sensory neuropathy associated with lung cancer that is well established clinically and histologically, and are compatible with those of axonal atrophy, partly related to unknown remote effects of cancer.

Adult↗
PubMed1993

Conformation dependence of antipeptide antibodies: characterization of cell-CAM105 isoform-specific antipeptide antibodies using proteins expressed in insect cells with baculoviral vectors.

Cell-CAM105 proteins are hepatocyte adhesion molecules of the immunoglobulin superfamily. The two isoforms, L-form and S-form, are highly homologous. In their extracellular domains, only 16 amino acid substitutions are found scattered in the first immunoglobulin domain of 105 amino acids. Peptide sequences containing these differences are selected for production of antibodies. Isoform specificities of these antibodies were evaluated with proteins expressed in the baculovirus-insect cell system. In immunoblot and immunoprecipitation experiments, anti-C1 antibody, which was generated against a peptide sequence found only in the cytoplasmic domain of the L-form, reacted only with the L-form cell-CAM105 protein. Anti-N antibody, which was generated against a pentadecapeptide of the L-form, reacted with both the S- and L-isoforms. The lack of isoform specificity of anti-N is not surprising because there is only one amino acid substitution in this pentadecapeptide sequence. In contrast, S3, a S-form-specific pentadecapeptide with four amino acid substitutions was able to elicit antibody, anti-S3, specific for the S-isoform. With the commonly used immunoprecipitation procedures, only anti-C1 was able to precipitate cell-CAM105 from the liver membrane. Anti-N and anti-S3 could precipitate the proteins only after the liver membrane samples had been boiled in the presence of denaturing agents. Hydropathy analysis of these peptides revealed that both peptides N and S3 are more hydrophobic than peptide C1, suggesting that the peptide fragments N and S3 are probably not located on the surface of the protein. This may explain why boiling of the protein sample was necessary before anti-N and anti-S3 could precipitate the protein. The present study demonstrates that it is possible to produce isoform-specific antibodies for highly homologous proteins. Furthermore, we show that special sample treatment may be required to expose the antigenic sites.

Adenosine Triphosphatases↗
PubMed1993

Preparative mini-slab gel continuous elution electrophoresis: application for the separation of two isoforms of rat hepatocyte cell adhesion molecule, cell-CAM 105, and its associated proteins.

A simple method for performing continuous elution electrophoresis using a mini-slab-gel system has been developed. The high resolving power of this method provides a means to separate complex mixtures of proteins and recover individual peptides in high yields. Recoveries between 89 and 99% were achieved using a single percentage gel to separate a mixture of standard proteins radiolabeled with 125I. Peptide fragments between 2.5 and 60 kDa generated by CNBr digestion of albumin were isolated within 150 min. Application of continuous elution electrophoresis to the purification of proteins associated with the rat hepatocyte cell adhesion molecule, cell-CAM 105, resulted in complete separation of the two predominant isoforms and the purification of three immunologically unrelated proteins that were coisolated during immunoaffinity chromatography.

Adenosine Triphosphatases↗
PubMed1993

Transient kinetics of the interaction of actin with myosin subfragment-1 in the absence of nucleotide.

The kinetics of the association of actin with myosin subfragment-1 (S1) has been studied by using S1 labeled at the sulfhydryl group SH1 with 5-(iodoacetamido)fluorescein (S1-AF). Upon rapid mixing in a stopped-flow apparatus, the fluorescence intensity of the fluorescein moiety increased by 50%, followed by a slower increase that was well resolved. This slow phase of the fluorescence change could not be fitted to either a monoexponential or a biexponential function, but it could be fitted to a sum of three exponential terms yielding three observed first-order rate constants (lambda i). The dissociation of acto.-(S1-AF) was studied by displacement of S1-AF from the complex with native S1. The dissociation kinetics was characterized by a single rate constant (approximately 0.012 s-1 at 20 degrees C), and this constant was independent of S1 concentration. Together with previous equilibrium data that were obtained under identified conditions for formation of acto-subfragment-1 (Lin, S.-H., and H. C. Cheung. 1991. Biochemistry. 30:4317-4323), a six-state two-pathway model is proposed as a minimum kinetic scheme for formation of rigor acto.S1. In this model, unbound subfragment-1 exists in two conformational states (S1' and S1) which are in equilibrium with each other, one corresponding to the previously established low-temperature state and the other to the high-temperature state. Each subfragment-1 state can interact with actin to form a collision complex, followed by two isomerizations to form two acto-subfragment-1 states (A.S1' and A.S1). Both isomerizations were visible in stopped-flow experiments. Two special cases of the model were considered: 1) a rapid pre-equilibration of the initial collision complex with actin and S1, and 2) trace accumulation of the collision complex. The first case required that the three combinations of the three observed rate constants be independent of actin concentration. The data were incompatible with this approximation. The other special case required that the sum of the lambda i vary linearly with actin concentration and the other two combinations of lambda i vary with actin concentration in a quadratic fashion. The present data were in agreement with the second case. At 20 degrees C and in 60 mM KCl, 2 mM MgCl2, 30 mM 2-([-hydroxy-1,1-bis(hydroxymethyl)ethyl]amino)ethanesulfonic acid, and pH 7.5, the biomolecular association rate constants for the interaction of actin with S1' and S1 were 8.58 x 10(5) and 1.11 x 10(6) M-1 s-1, respectively.

Actins↗
PubMed1993

Student's exposure to volatile organic compounds while commuting by motorcycle and bus in Taipei City.

This study examined student's exposure to volatile organic compounds (VOCs) while commuting by bus and motorcycle in Taipei, Taiwan in the winter of 1992. A total of 19 target C5-C10 VOCs on three most frequently used commuting routes were collected on Tenax-GC adsorbent tubes. The VOCs were desorbed by thermal desorption method and analyzed by GC-MS. The most abundant VOC exposure experienced by commuters was to toluene. Several alkylated benzenes, such as propyl benzenes, ethyl-methyl-benzenes and trimethyl-benzenes, were relatively abundant on the roads in Taipei. The mean benzene concentration measured in buses was 173 micrograms/m3 and motorcycles. On the average, the commuters in Taipei experienced about three to eight times higher VOC concentrations than the commuters in Los Angeles, California. Higher VOC concentrations were measured on motorcycles than in buses. The VOC concentrations were not significantly different between morning and afternoon commutes, nor among the three commuting routes. VOC concentrations measured in classroom at three schools in downtown Taipei did not vary significantly on each sampling day. However, at each school the in-classroom VOC concentrations varied significantly over the six consecutive sampling days. The VOC concentrations measured on the roads were about five times higher than those measured in the school classrooms in the city. Moderate to high correlations were found among most of the measurements of the 19 VOCs. The survey questionnaire indicated that daily commuting time ranged from 45 minutes for elementary school students to 95 minutes for vocational school students.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1993

Cortisol levels, immune status, and mood in homosexual men with and without HIV infection.

OBJECTIVE: Alteration in cortisol levels has been reported in HIV infection and may be related to levels of psychiatric distress and immune function. The goals of this study were to assess cortisol levels in subjects with HIV infection and to determine whether stress-related activation of the hypothalamic-pituitary-adrenal (HPA) axis results in compromised immune function. METHOD: As part of a longitudinal study, the authors assessed urinary free cortisol levels of HIV-positive and HIV-negative homosexual men at four time points during a period of 2 years. Subjects' scores on the Hamilton depression and anxiety rating scales, medical stage of HIV infection, and CD4+ and CD8+ cell counts were also assessed. Repeated measures analysis of variance was used to determine whether subjects' cortisol levels at the four time points differed according to their serological status. Pearson correlation coefficients were computed to examine the relationships among mood ratings, cortisol levels, medical stages, and cell counts. RESULTS: Cortisol levels did not differ significantly between the HIV-positive and the HIV-negative subjects and were not associated with stage of medical illness in HIV infection. An association between cortisol level and depressed and anxious mood was found only at the first assessment. Cortisol level was not associated with CD4+ cell count in either group of subjects. CONCLUSIONS: There were no significant elevations of cortisol levels in the HIV-infected subjects, nor was there consistent evidence for stress-related activation of the HPA axis in either the HIV-positive or the HIV-negative subjects.

Adult↗
PubMed1993

[Home health care and the social supports for community-dwelling stroke patients].

The stroke survivors often suffer various degrees of disability and require some forms of assistance in their activities of daily living, and continuing care for the community-dwelling stroke survivors. This article includes three components to explain the needs of continuing care for the stroke survivors: the significance of continuing care for the stroke survivors, current problems of social support systems and future perspective on continuing care for the stroke survivors.

Cerebrovascular Disorders↗
PubMed1993

Serum osteocalcin and vitamin D in postmenopausal diabetic azotemics.

To clarify the role of serum vitamin D and bone remodeling markers in postmenopausal diabetic azotemics, we designed a study involving 3 different postmenopausal patient groups. Group I consisted of 20 diabetic women with renal insufficiency who were not yet on dialysis therapy. Group II consisted of 15 age-matched nondiabetic women with comparable degrees of renal insufficiency. Group III consisted of 20 age-matched women with normal renal function. We investigated the overnight fasting serum 25 (OH) vit-D, 1,25(OH)2 vit-D3, osteocalcin (OC), bone isoenzyme of alkaline phosphatase (ALK-PB) and intact parathyroid hormone (I-PTH) levels in these cases. The serum I-PTH and OC levels were statistically significantly higher, whereas 1,25(OH)2vit-D3 were significantly lower in Group I and Group II patients than in Group III patients. We found no significant correlation between elevation of I-PTH and reduced 1,25(OH)2 vit-D3 levels in Group I and Group II patients. I-PTH levels correlated positively with OC in Group I and Group II patients. There was no significant difference in serum 25(OH) vit-D among these 3 groups of patients. We conclude that (1) serum OC level may serve as a good parameter in evaluating secondary hyperparathyroidism in postmenopausal azotemics with or without diabetes, (2) even in the presence of menopause, renal failure per se is the main factor in determining serum 1,25(OH)2 vit-D3 levels in diabetic azotemics.

Aged↗
PubMed1993

Captopril-induced agranulocytosis: a case report.

Captopril 12.5 mg twice daily was initially administered given to a woman with chronic renal failure and hypertension. Three weeks later, she developed chills, high fever and sore throat. Hemogram showed severe neutropenia; the white cell count showed 600/cu mm; bone marrow aspirate and biopsy revealed a paucity of myeloid series. Antineutrophil antibody was not detected in the serum. The neutrophil counts returned to normal after captopril was discontinued two weeks later. We recommend that the peripheral white blood cell count in patients whom captopril is prescribed must be carefully monitored in the first three months, particularly in those with impaired renal function.

Aged↗
PubMed1993

Immunoglobulin and T cell receptor beta chain gene rearrangements and Epstein-Barr viral DNA in tissues of Hodgkin's disease in Taiwan.

Nineteen patients with Hodgkin's disease (HD), representing 4 different subtypes, were examined for immunophenotype and immunogenotype. Quantitative immunophenotypic analysis of 13 cases revealed a predominance of Leu1 and Leu3 T cells in all subtypes, except in the case of HD lymphocytic-depression (HDLD). The positive rate of LeuM1 and Ki1 in Reed-Sternberg (RS) cells was 65% (11/17) and 73% (11/15), respectively. In DNA hybridization analysis, 5 of the 19 cases of HD were found to have gene rearrangements--immunoglobulin (Ig) gene rearrangements in 3 cases and T cell receptor beta chain (TCR beta) gene rearrangements in 2 cases. Epstein-Barr (EBV) DNA genomes were detected in 8 cases, including 2 of 5 cases which previously had been shown to contain clonal Ig and TCR beta gene rearrangements. By contrast, there were no detectable cytomegalovirus (CMV) DNA sequences in 19 cases of HD or 30 cases of non-Hodgkin's lymphoma (NHL). Although our findings differed somewhat from those obtained on Westerners, they suggest the presence of a monoclonal lymphoid population in HD patients and that the EBV is related to the etiology of HD.

DNA, Viral↗
PubMed1993

A survey on drug-related hospitalization in a community teaching hospital.

We retrospectively studied 2,695 patients admitted to the Department of Medicine over a 10-month period in 1990 to determine the incidence of drug-related hospitalization. A drug-related problem was identified as the primary cause of hospitalization in 109 (4.0%) admissions. The incidence was significantly greater in the elderly group as compared with the non-elderly group (5.2% vs 3.2%). Non-steroidal anti-inflammatory drugs, hypoglycemic agents, herbal medicine, adrenocorticosteroids and antihypertensive drugs were most often involved. The five most common adverse events were upper gastrointestinal tract bleeding, skin rashes, hypoglycemia, hypercorticism and hepatitis. Iatrogenic disease was fatal in 2 cases. Patients used drugs without medical supervision in 45 cases. In view of the increasing complexity of modern pharmacotherapy and the popularity of self-medication in our society, educational efforts should be enhanced for medical professionals and the general population to reduce the risk of drug-related hospitalization.

Adolescent↗