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Biomedical subjects

S H Hsu

Publications and source records attributed to S H Hsu.

At least 55 records · Page 3Linked to original sources
PubMed1994

Functional expression and site-directed mutagenesis of a synthetic gene for alpha-bungarotoxin.

In order to explore the structure-function relationships of the curare mimetic alpha-neurotoxins we have constructed and cloned a synthetic gene for Bungarus multicinctus alpha-bungarotoxin which is expressed in Escherichia coli. The recombinant alpha-bungarotoxin is expressed as a fusion protein with alpha-bungarotoxin linked to the COOH-terminal end of the T7 Gene 9-encoded coat protein. After treatment of the fusion protein with Factor Xa protease, a recombinant alpha-bungarotoxin is released that co-migrates with authentic alpha-bungarotoxin upon reverse-phase high performance liquid chromatography and ion-exchange chromatography. Final yields of active recombinant alpha-bungarotoxin were about 0.4 mg/liter of starting bacterial culture. The recombinant alpha-bungarotoxin contains 10 additional residues linked to the NH2-terminal Ile of the alpha-bungarotoxin sequence due apparently to the inaccessibility of the engineered cleavage site to Factor Xa. Nevertheless, the recombinant alpha-bungarotoxin is capable of binding to the nicotinic acetylcholine receptor with an apparent affinity that is only decreased approximately 1.7-fold from that of authentic alpha-bungarotoxin. Alanine substitution of a residue, Asp30, highly conserved among alpha-neurotoxins and previously suggested to play a key role in receptor recognition, resulted in a recombinant alpha-bungarotoxin whose receptor binding activity is indistinguishable from authentic alpha-bungarotoxin.

Alanine↗
PubMed1994

Role of viscoelasticity in tube model of airway reopening. I. Nonnewtonian sols.

This investigation used a previously described bench-top device (Gaver et al., J. Appl. Physiol. 69: 74-85, 1990) to examine the role of nonnewtonian and viscoelastic fluids on events at reopening of a closed flexible tube. Aqueous sodium alginate solutions with and without calcium chloride and sodium dodecyl sulfate in desired concentrations provided fluids with a wide range of surface tensions, storage and loss moduli, and nonnewtonian steady shear viscosity. Dimensionless analysis, using the shear rate-dependent viscosities, was applied to reduce reopening pressure-meniscus velocity data to a master curve. With regard to fluid properties, we found that 1) fluid elasticity strongly changes the pressure-velocity relationship, causing flow instability at higher meniscus velocities; 2) decreasing surface tension gives rise to a smaller yield pressure for reopening; and 3) whereas larger tubes are easier to open, smaller tubes produce additional shear thinning of the lining fluid. These results suggest that, for both the upper (large) and lower (small) airways, nonnewtonian and viscoelastic properties of the mucosal fluid modify the time of closure and rate of reopening.

Alginates↗
PubMed1993

Analysis of a large kindred with Blau syndrome for HLA, autoimmunity, and sarcoidosis.

OBJECTIVE: To determine whether HLA and autoimmunity contribute to the pathogenesis of Blau syndrome (familial granulomatous arthritis, uveitis, and rash) and evaluate whether this condition is related to sarcoidosis. DESIGN: Large family survey. SETTING: General community, Green Bay, Wis, and two tertiary care medical centers in Philadelphia, Pa. PARTICIPANTS: Thirty-six family members and spouses from a large kindred with Blau syndrome. SELECTION PROCEDURES: Volunteer and convenience sample. INTERVENTIONS: None. MEASUREMENTS AND RESULTS: Ten affected and many unaffected subjects were personally examined. Medical records and previous biopsy reports and specimens, when available, were reviewed. Two affected subjects had skin biopsies performed and three affected adult subjects were tested with Kveim skin-test reagent. Serologic and genomic class I and class II HLA typing was performed on 27 affected and unaffected subjects. All 13 living affected subjects and the one obligate carrier had the following assays performed; antinuclear antibody titer, rheumatoid factor, serum angiotensin converting enzyme level, quantitative immunoglobulins of the IgG, IgM, and IgA classes, and clinical chemistry profiles. Several had complete blood cell counts and erythrocyte sedimentation rates performed. Four affected subjects, one possibly affected subject, and one obligate carrier were newly identified. Flexion contractures of the fingers and toes (camptodactyly) were found, for the first time, to be a phenotype characteristic. Earlier onset and worsening of symptoms in succeeding generations (anticipation) were observed. Sixteen HLA haplotypes were identified. No conclusive evidence for linkage between these haplotypes and phenotype expression could be demonstrated. All 13 affected subjects, however, carried the DR2 (DR beta 1*1501) and/or DR4 (DR beta 1*0401) allele. There was no evidence of hypercalcemia, hypergammaglobulinemia M, rheumatoid factor production, or abnormal blood cell counts. Two affected subjects had low-titer antinuclear antibody screening tests, five had mild to moderately elevated IgG and/or IgA levels, two had raised serum angiotensin converting enzyme levels, and three had mild elevation of the erythrocyte sedimentation rate. All three subjects tested with Kveim skin-test reagent showed no reactivity by visual inspection. Both subjects who had had skin biopsies performed had evidence of granulomatous inflammation. CONCLUSIONS: This family's illness is distinct from both classic and early-onset sarcoidosis. There is minimal evidence for autoimmunity and systemic inflammation. Camptodactyly should be added to the list of syndrome-defining characteristics. Although HLA haplotypes do not appear to segregate with affected subjects, HLA-DR2 and HLA-DR4 subtypes may play a permissive role in phenotype expression. This family represents a unique opportunity to define the molecular mechanisms involved in the initiation of arthritis and uveitis in humans. Genetic linkage studies to determine the chromosomal location of the Blau syndrome gene are in progress.

Adolescent↗
PubMed1993

Psychophysical modelling of lifting capacity of Chinese males using strength variables.

This study used the psychophysical approach to determine the maximum acceptable weight of lift (MAWL) for 12 young Chinese male subjects, and used strength variables as predictors to develop prediction models. Each subject performed 12 different lifting tasks involving three lifting heights and four lifting frequencies. The results showed that both the dynamic and static models developed in this study could predict the MAWL with a reasonable degree of accuracy. However, a comparison of the models revealed that the use of the dynamic model resulted in less PRESS (PRediction Error Sum of Squares) statistics and higher [Formula: see text] values than the static model. Isoinertial 1.83 m maximum strength (T1) and the isoinertial elbow-height strength, tested on an incremental weightlifting machine, were found to be the best screening test. This was different from a previous study that recommended T1 as the most promising single screening test for Occidentals.

Journal Article↗
PubMed1993

Reappraisal of skeletal tuberculosis: role of radiological imaging.

Skeletal tuberculosis (TB) can present with a broad spectrum of variable clinical manifestations which may cause diagnostic difficulties. To further elucidate these possible diagnostic pitfalls, 14 cases of bacteriologically or histologically proven skeletal TB, which were initially diagnosed otherwise, are reviewed. In five cases with lumbar or midthoracic spinal involvement, concomitant traumatic history and degenerative radiological changes were the main reasons for not suspecting the possibility of skeletal TB. A differential diagnosis between TB and metastatic lesions can be difficult in the very early stage when X-ray images usually have a low contrast and are not sharp. In nine cases with bone and joint involvement, a long-lasting discharging sinus led the clinician to an initial impression of septic arthritis; sometimes concomitant gouty arthritis can mask the clinical manifestations of skeletal TB. In five cases, minor erosive lesions over the peripheral margin of the involved bone were the earliest findings on the plain X-ray films and were overlooked. To facilitate the early diagnosis of skeletal TB and to avoid the possibility of complications in the management of patients, medical practitioners should be familiar with the usual forms of the condition and the wide variety of clinical manifestations.

Adult↗
PubMed1992

Demonstration of passenger leukocytes in a case of Epstein-Barr virus posttransplant lymphoproliferative disorder using restriction fragment length polymorphism analysis.

Lymphocytic populations of the posttransplant lymphoproliferative disorder in a completely matched renal allograft and a recipient's regional lymph node were examined, using restriction fragment length polymorphism analysis with probe YNH24 to the variable number tandem repeat D2S44. The donor's DNA was found in lymphocytes extracted from both the grafted kidney and the recipient's lymph node 26 days after engraftment. In both these organs, the results of in situ hybridization with a terminally biotin-labeled oligonucleotide probe to the Not I tandem repeat region of the Epstein-Barr virus (EBV) genome, as well as those of Southern blot hybridization to the EBV nuclear antigen region of the EBV genome, were positive. These findings confirmed the presence of the donor's lymphocytes ("passenger leukocytes") in the host nodal tissue in human renal transplantation and implicated EBV as playing a role in the development of posttransplant lymphoproliferative disorder. It is speculated that the EBV proliferative stimulus contributed to the recipient and the donor lymphocyte expansions. Alternatively, the proliferation of both lymphocyte populations could result from a mutual stimulation by minor histocompatibility or other antigens.

Cell Division↗
PubMed1992

Prolonged remission of accelerated phase Philadelphia chromosome negative chronic myeloid leukemia following autologous recovery of normal hematopoietic elements after busulfan/cyclophosphamide and allogeneic marrow transplantation.

We describe here a patient with accelerated phase Philadelphia chromosome (Ph1) negative chronic myelogenous leukemia without BCR gene rearrangement, who received an allogeneic bone marrow transplant following a conditioning regimen consisting of busulfan (BU) and cyclophosphamide (CY). Hematopoiesis was restored following splenectomy performed 1 month post-transplant. There were no distinguishing cytogenetic differences between donor and host. Five years post-transplant the patient relapsed with the original disease. Restriction fragment length polymorphism (RFLP) studies performed at that time exhibited host specific DNA markers suggesting recurrent leukemia of host origin. RFLP analysis of the cells cryopreserved immediately post-transplant also revealed all cells to be of host origin. This patient experienced 5 years of remission with autologous hematopoietic recovery from an aggressive myeloproliferative disorder after high dose BU and CY without engraftment of donor hematopoietic cells.

Adult↗
PubMed1991

An investigation for determining the optimum length of chopsticks.

Chopsticks are one of the most simple and popular hand tools ever invented by humans, but have not previously been investigated by ergonomists. Two laboratory studies were conducted in this research, using a randomised complete block design, to evaluate the effects of the length of the chopsticks on the food-serving performance of adults and children. Thirty-one male junior college students and 21 primary school pupils served as subjects for the experiment. The results showed that the food-pinching performance was significantly affected by the length of the chopsticks, and that chopsticks of about 240 and 180 mm long were optimal for adults and pupils, respectively. Based on these findings, the researchers suggested that families with children should provide both 240 and 180 mm long chopsticks. In addition, restaurants could provide 210 mm long chopsticks, considering the trade-offs between ergonomics and cost.

Journal Article↗
PubMed1991

Influence of the mobile phase on salmon calcitonin analysis by reversed-phase liquid chromatography.

The retention properties of calcitonins on a reversed-phase column are examined using salmon calcitonin as the model compound. The effect of the concentration of organic modifier, buffer strength, pH of the mobile phase, and ion-pair reagent are studied. In the absence of an ionic modifier in the eluent the calcitonin peak shapes are not symmetrical. The addition of 0.1% trifluoroacetic acid (TFA), however, results in good peak characteristics without the need to add nonvolatile salts. The retention of the calcitonins was found to be very sensitive to the concentration of the organic modifier (acetonitrile) present in the mobile phase. A change of pH between 2 and 5 has only a slight effect of the k' of salmon calcitonin, but the k' increases significantly at higher pH values. The addition of a phosphate buffer to the mobile phase and an increase in the buffer concentration (0-0.2 M) causes a decrease in the retention of salmon calcitonin. Evidence shows that reproducible, quantitatively measurable data can be obtained using reversed-phase chromatography if the ion-pairing reagent and organic modifier concentrations are carefully controlled. The system also shows a good selectivity for the calcitonin series. Therefore, both highly selective methods (qualitative) as well as quantitative methods for analytical, pharmaceutical, and manufacturing use can be developed by adjusting the high-performance liquid chromatography (HPLC) conditions as discussed.

Amino Acid Sequence↗
PubMed1988

Determination of a new inotropic agent in human plasma by high-performance liquid chromatography.

A new orally active inotropic agent, 6-[3,4-dihydro-3-methyl-(2H)-2-oxoquinozolinyl)]-4,5-dihydro-3- (2H)-pyridazinone (I), is currently under investigation. In support of clinical studies, a HPLC assay for the analysis of compound I in human plasma has been developed. The method involved a solid-phase extraction using C18 cartridge columns washed with methanol-water (20:80) and eluted with acetonitrile-water (70:30). The eluate was then extracted with dichloromethane. A reversed-phase alkylphenyl-bonded column was used as the analytical column. The mobile phase was a mixture of methanol, acetonitrile, 2-propanol and phosphate buffer (pH 4.6). A wavelength of 311 nm was used for detection. The limit of detection of the assay was 2 ng/ml, and the limit of quantitation was 5 ng/ml. A linear calibration range of 5 ng/ml to 1200 ng/ml was obtained with a correlation coefficient less than 0.99. The precision and accuracy were evaluated by analyzing samples of three different concentrations (n = 5), 40, 200 and 800 ng/ml in plasma. The coefficients of variation and the differences from nominal values were less than 10%. The average recovery for 5, 50 and 100 ng/ml of analyte in plasma was about 90%. This assay has been applied to clinical studies with satisfactory performance and to plasma of different species in preclinical studies.

Cardiotonic Agents↗
PubMed1988

Identification and quantitation of trenbolone in bovine tissue by gas chromatography-mass spectrometry.

Identification and quantitation of trace amounts of trenbolone in bovine tissue by capillary gas chromatography-mass spectrometry-selected-ion monitoring (GC-MS-SIM) has been developed. Three-phase liquid-liquid extraction using a mixture of water-acetonitrile-dichloromethane-hexane was utilized for the sample extraction from tissue. Target compounds were extracted from the tissue into the acetonitrile layer. The residue from this extraction was then subjected to solid-phase extraction by C18 and silica gel disposable cartridges using methanol-water and benzene-acetone as eluents. To overcome extensive matrix interferences, preparative reversed-phase high-performance liquid chromatographic separation was used with an octadecyl-bonded column using methanol-water as mobile phase for sample clean-up prior to GC-MS analysis. A structural analogue of trenbolone, 19-nortestosterone, was chosen as the internal standard for quantitation by GC-MS. The sample was co-injected with N,O-bis (trimethylsilyl) trifluoroacetamide-1-(trimethylsilyl) imidazole (95:5, v/v) for flash heater derivation. Identification and quantitation were simultaneously carried out by SIM of characteristic ions of the trimethylsilyl derivatives of trenbolone and 19-nortestosterone. The limit of detection for trenbolone and epitrenbolone was 0.5 ppb in muscle and liver tissue. A comparison of sensitivity and specificity between GC-MS under electron ionization in addition to positive- and negative-ion chemical ionization conditions using methane reagent gas is also discussed.

Animals↗
PubMed1986

Mixed-mode hydrophobic ion exchange for the separation of oligonucleotides and DNA fragments using HPLC.

Hydrophobic anion exchangers were formed by cobonding both ionic and hydrophobic ligands to silica gel. These phases were used to separate single-stranded oligonucleotides and double-stranded DNA restriction fragments. By varying the ratio of n-octyldimethylsilane and either 3-chloropropyldimethylsilane or 4-chlorobutyldimethylsilane added during silanization a series of mixed-ligand or mixed-mode stationary phases was created. Concentration and ratio of bonded ligands were determined using a new gas chromatography fluorination method. Total ligand coverage was found to approach 2.1 ligands nm-2 for n-octyldimethylsilane. Bonding reproducibility for mixed-mode phases was good. Nucleic acid separations were achieved under gentle mobile phase conditions by using the stationary phase as an easily modifiable variable.

Chromatography, Gas↗
PubMed1986

Quantitative retention relationships as a function of mobile and C18 stationary phase composition for non-cogeneric solutes.

Twelve non-homologous solutes with a wide range of functional groups were chromatographed on a series of well-characterized stationary phases with a range of methanol-water mobile phases. Retention correlations were found for quantum mechanically calculated molecular parameters. These parameters, the total molecular energy, and the maximal excess electronic charge difference, were found to be better descriptors of retention than the dipole moment or fragmental constants. The implication of these results in terms of retention mechanisms on reversed-phase materials are discussed.

Chemical Phenomena↗
PubMed1986

Cells homozygous for two HLA-DR7-associated HLA-D specificities express highly similar DR molecules but different DQ molecules.

The Ia molecules expressed by cells homozygous for two distinct HLA-DR7-associated HLA-D specificities, Dw7S and Dw11L, were compared. The complete Ia phenotypes of these cells are DR7, DRw53, DQw2, Dw7S, DPw4 and DR7, DRw53, DQw3, Dw11L, DPw4, respectively. Immunofluorescence analysis revealed that three DQ-specific monoclonal antibodies (Leu-10, 33.1, and HK-19), which detect polymorphic DQ determinants that do not correspond to known serologic specificities, are nonreactive with DR7, Dw7S cells but are reactive with DR7, Dw11L cells. The DR molecules isolated from Dw7S and Dw11L cells are very similar and comigrate when analyzed together by two-dimensional gel electrophoresis. In contrast, the DQ molecules isolated from these cells are structurally distinct: the DQ beta chains of DQw2-bearing molecules from Dw7S cells are very basic, while those of DQw3-bearing DQ molecules from Dw11L cells are more acidic. The finding that two DR7, D-different cells express indistinguishable DR molecules and structurally distinct DQ molecules documents a unique pattern of Ia molecular organization which is different from those previously described for the DR2-, DR4-, or DRw8-associated HLA-D specificities.

Antibodies, Monoclonal↗
PubMed1986

HLA-D restriction of "naturally occurring" MLR suppressor cells in acquired common variable hypogammaglobulinemia.

Cells with capacity to suppress the mixed lymphocyte response (MLR) were detected in two patients with acquired common variable hypogammaglobulinemia (ACVH). No specificity with respect to the stimulating HLA type was observed. In one case of ACVH available for extensive study, there was evidence for HLA-D restriction of the suppressor cells. The patient's lymphocytes specifically suppressed the MLR of subjects who carried the same HLA-D type. Family studies confirmed that the suppressor activity was restricted to HLA-D, not DR, and segregated with the appropriate HLA haplotype. These observations suggest that an immune suppressor gene mapping in the HLA region may be involved in the pathogenesis of common variable hypogammaglobulinemia.

Agammaglobulinemia↗
PubMed1985

Immunochemical and genetic studies of Amb.t. V (Ra5G), an Ra5 homologue from giant ragweed pollen.

Giant ragweed pollen allergen Amb.t. V (Ra5G), a homologue of short ragweed pollen Amb.a. V (Ra5S), was isolated in ultrapure form from a 16-min extract of ragweed pollen by a combination of molecular sieving through an Amicon hollow fiber cartridge (H1P5), cation-exchange chromatography, and gel filtration. The size was found to be 4400 daltons (D) by amino acid analysis and 6000 D by SDS-PAGE, and the pI was 8.3 as determined by isoelectric focusing. There was no cross-reactivity detected between the two Amb. V antigens by immunodiffusion and IEP with the use of hyperimmune antisera raised against crude or highly purified antigens. Cross-reactivity between the two Amb. V antigens was further investigated by inhibition double antibody radioimmunoassay by using the sera of nine selected ragweed-allergic patients who had recently been immunized with either mixed short-giant ragweed pollen extract or with short ragweed extract alone and who had IgG antibodies (Ab) to Amb.t. V and generally to Amb.a. V. Unlabeled Amb.t. V did not inhibit the binding of 125I-Amb.a. V to the IgG Ab in any of the sera tested. Conversely, unlabeled Amb.a. V produced some inhibition of the binding of 125I-Amb.t. V to the patients' IgG Ab, primarily in those patients who had received immunotherapy with short ragweed alone. This weak cross-reactivity was probably a result of the primary structural homology between the two protein allergens. The sera from two groups of ragweed-allergic individuals were investigated for the presence of IgG and IgE Ab to Amb.t. V. The presence of IgG Ab was found to be associated both with previous (or current) immunotherapy with giant ragweed extract and with HLA-Dw2. The HLA association is of interest in view of the previously established association between Dw2 and response toward the homologue Amb.a. V. The result suggests the existence of a similar genetic control at the primary level of antigenic recognition of the two Amb. V antigens.

Allergens↗