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S Hsieh

Publications and source records attributed to S Hsieh.

At least 37 records · Page 2Linked to original sources
PubMed1995

Structure and regulation of the ALS gene.

The mouse ALS gene spans at least 6 kb. It contains 2 exons which encode a protein highly homologous to human and rat ALS. It was localized to mouse chromosome 17 by flourescent in situ hybridization. The 5' flanking region lacks a TATA box but contains GC boxes that may be recognised by transcription factors such as Spl. Hepatic ALS mRNA is decreased in rats following hypophysectomy, and restored by stimulated ALS promoter activity in a rat hepatoma cell line, but not in 3T3-F442A mouse preadipocyte fibroblasts, suggesting that utilisation of the ALS promoter is cell-type specific. The rat hepatoma system is a promising system to study the regulation of ALS gene expression, and the signalling pathways of CH regulation.

Animals↗
PubMed1995

Stimulus-driven or autonomous shift or attention?

Hsieh and Allport studied shifts of attention in semantic space, using a semantic monitoring task based on rapid, serial, visually presented sequences of words. They reported that following a shift of criterion, accuracy of semantic monitoring dropped abruptly to a low level, then gradually recovered to reach the preshift level over successive stimuli in the sequence. They further examined the nature of the recovery of accuracy following a shift of criterion. Despite the striking results they obtained, some problems of their design remained. Hence, the current research replicated Hsieh and Allport's experiments with some modifications and showed that a shift of semantic criterion in a rapidly presented sequence indeed appears to be stimulus-driven rather than an autonomous process.

Adult↗
PubMed1995

Set-shifting aptitude in Parkinson's disease: external versus internal cues.

A modified version of the odd-man-out test was used to investigate set-shifting aptitude in 12 patients with Parkinson's disease. We asked subjects to execute in alternation two different sorting rules over successive items. External and internal cueing conditions were employed. Patients with Parkinson's disease were impaired on the tasks with internal cues but were normal on the tasks with external cues. Moreover, the shift costs were consistently larger for the shift to the easier task than the shift to the more difficult task. These findings indicated that the model of 'Supervisory Attentional System' may not be sufficient to explain the data as Brown and Marsden (1988) originally suggested.

Aged↗
PubMed1995

Ifosfamide/carboplatin/etoposide chemotherapy in patients with metastatic non-small cell lung cancer.

We have evaluated the combination of ifosfamide, carboplatin, and etoposide (ICE) along with mesna in 46 patients with stage IV non-small cell lung cancer. Treatment consisted of ifosfamide (1.25 g/m2/d with mesna) and etoposide (80 mg/m2/d) given intravenously on days 1 to 3 and carboplatin (300 mg/m2) given intravenously on day 1 every 4 weeks. Eligibility criteria included measurable disease; adequate hematologic, hepatic, and renal functions; no prior chemotherapy; and an Eastern Cooperative Oncology Group performance status (PS) of 0 to 3. Two patients were lost to follow-up and one had received prior chemotherapy, leaving 43 patients evaluable for response and toxicities. There were 27 male and 16 female patients. Twenty-three patients had a PS of 0 or 1 and 20 had a PS of 2 or 3. Eighteen patients had received prior radiotherapy. There were two complete responses and nine partial responses. The response rate was 35% in PS 0 or 1 patients and 15% in PS 2 or 3 patients. The most frequent toxicity was myelosuppression; 44% of patients experienced grade 3 or 4 leukopenia and 14%, grade 3 or 4 thrombocytopenia. Patients receiving prior radiation were significantly more prone to develop leukopenia (P = .01). Five patients developed leukopenic fever, and three died of sepsis. Gastrointestinal toxicities were mostly mild. No neurologic or genitourinary toxicities were observed. The median length of survival was 209 days for patients with a PS of 0 or 1 and 123 days for the entire group. The 1-year survival rate was 22% and 19%, respectively, in these two patient subgroups. ICE is an active regimen in patients with metastatic non-small cell lung cancer and a good PS. Myelosuppression is the major dose-limiting toxicity. Hematopoietic growth factors may be indicated in subsequent studies, especially in patients who had prior radiation therapy. The therapeutic effect of ICE on patients with a poor PS remains unsatisfactory and requires further investigation.

Adult↗
PubMed1994

Recombinant human insulin-like growth factor (IGF)-binding protein-6 inhibits IGF-II-induced differentiation of L6A1 myoblasts.

Insulin-like growth factor-binding protein-6 (IGFBP-6) is an O-linked glycoprotein that binds insulin-like growth factor-II (IGF-II) with marked preferential affinity over IGF-I. Recombinant human IGFBP-6 (rhIGFBP-6) was synthesized by COS-7 monkey kidney cells that were transiently transfected with a eukaryotic expression vector into which a complementary DNA for IGFBP-6 modified for optimal translation had been inserted. rhIGFBP-6 was similar to IGFBP-6 purified from human cerebrospinal fluid with respect to IGF binding and O-glycosylation. The effect of rhIGFBP-6 on IGF-induced L6A1 myoblast differentiation was studied using creatine kinase activity as an index of differentiation. rhIGFBP-6 inhibited differentiation initiated by IGF-II in a dose-dependent manner, inhibition was complete when rhIGFBP-6 was present in a slight molar excess. In contrast, rhIGFBP-6 had no effect on IGF-I-induced differentiation, even when coincubated in a 5-fold molar excess. These results are consistent with the preferential affinity of IGFBP-6 for IGF-II. As cell association and proteolysis have been associated with the potentiation, rather than the inhibition, of IGF action by IGFBPs, we investigated whether they occurred in the L6A1 myoblast system. After incubation of L6A1 myoblasts with rhIGFBP-6, IGFBP-6 was recovered from the medium, but not from cell lysates or extracellular matrix. In addition, [125I]IGFBP-6 did not bind to myoblast monolayers, and there was no evidence that proteolysis had occurred. Together, these results indicate that rhIGFBP-6 remains intact and soluble and, hence, inhibits IGF-II-induced differentiation. The fidelity of the IGFBP-6 expression system used for these studies will enable us to use this system to determine how structural modifications of the protein affect the modulation of IGF action by IGFBP-6.

Animals↗
PubMed1994

Shifting attention in a rapid visual search paradigm.

A method is introduced for studying shifts of attention in semantic space, testing 56 subjects in four experiments on a semantic monitoring task based on rapid, serial, visually presented (RSVP) word-sequences. Following a cue to shift attention, accuracy of semantic monitoring drops abruptly to a low level, then gradually recovers to reach preshift levels over successive stimuli in the RSVP sequence. Using this method, we compared two kinds of criterion-shifts, one requiring a set-reversal ('reversal shifts'), the other involving a shift between orthogonally defined categories ('orthogonal shifts'); no differences were found. We have also examined the difference in a shift between two different processing domains (semantic vs typographic) compared with a shift of criterion within the same processing domain. The results showed no differences for within- vs between-domain shifts. Finally, we studied the time-course of a semantic attention shift. Execution of a semantic shift did not follow an internally controlled time-course but was a direct function of the rate of stimulus presentation. No evidence was found for the operation of a 'supervisory attentional system' independent of external stimulus triggering.

Attention↗
PubMed1993

Binding of mutants of human insulin-like growth factor II to insulin-like growth factor binding proteins 1-6.

A family of six specific insulin-like growth factor binding proteins (IGFBPs) modulates the biological actions of the insulin-like growth factors, IGF-I and IGF-II. In the present study, we determined the binding affinity of purified human IGFBPs 1-6 for recombinant human IGF-II mutants whose binding to IGF-I, IGF-II/mannose 6-phosphate, and insulin receptors was previously reported (Sakano, K., Enjoh, T., Numata, F., Fujiwara, H., Marumoto, Y., Higashihashi, N., Sato, Y., Perdue, J. F., and Fujita-Yamaguchi, Y. (1991) J. Biol. Chem. 266, 20626-20635). Of the regions studied, the most important determinants of IGF-II binding to the IGFBPs were A-domain residues 48-50 and B-domain residue 26. Substitution of residues 48-50 with the analogous residues from human insulin (Thr-Ser-Ile) reduced binding to IGFBP-1, -5, and -6 more than 50-fold and to IGFBP-4 by 15-50-fold; binding to IGFBP-2 and -3 was reduced 6-12-fold. The same substitution markedly reduced binding to the IGF-II/mannose 6-phosphate receptor but not to IGF-I or insulin receptors. Although substitution of residues 54 and 55 with the analogous residues from IGF-I (Arg-Arg) abolished binding to the IGF-II/mannose 6-phosphate receptor, binding to IGFBPs was not substantially affected. Substitution of Phe26 with Ser or Leu, which decreased binding to the IGF-I and insulin receptors, reduced binding to IGFBP-1 and -6 up to 80-fold, but had lesser effects on the other IGFBPs. [Leu27]IGF-II and [Leu43]IGF-II, which had a more markedly reduced affinity for the IGF-I and insulin receptors than did [Ser26]IGF-II, were bound by the IGFBPs with relatively unchanged affinity compared with IGF-II. Thus, the determinants of IGF-II binding to IGFBPs partially overlap those for the IGF-II/mannose 6-phosphate receptor and overlap those for the IGF-I receptor to a lesser extent. IGFBP-1 and IGFBP-6 are most sensitive to changes in IGF-II structure, although IGFBP-1 binds IGF-I and IGF-II with equal affinity, whereas IGFBP-6 has a marked preferential binding affinity for IGF-II. IGF-II mutants with selective impairment in recognition by specific IGFBPs or receptors will provide a useful tool for dissecting the role of the different IGF binding macromolecules in the mediation of IGF-II actions.

Amino Acid Sequence↗
PubMed1993

Ethnic and gender differences in drug users' perceived need for treatment.

Little is known about ethnic and gender variation in drug users' perceived need for treatment or about the predisposing factors that might account for such variation. Among 1,170 drug-using arrestees in Los Angeles, perceived need for treatment is positively related to these predisposing factors: self-reported drug dependence, attitude toward treatment for drug use, and occurrence of drug-related problems other than dependence. Self-reported drug dependence is higher among women and accounts for the greater perceived need reported by women. Hispanics are less likely to perceive a need for treatment. Among daily drug users, both Hispanics and Africans Americans are less likely to do so. These ethnic differences are not explained by self-reported drug dependence or any other predisposing factor. Implications for treatment referral, intake, and counseling are discussed.

Adolescent↗
PubMed1993

Methadone maintenance and needle/syringe sharing.

Drug users who inject drugs while in treatment share needles/syringes less often than users not in treatment. This relationship may reflect treatment processes, such as cognitive or normative change, by which treatment clients are influenced to lower their HIV infection risk. However, reduced needle/syringe sharing among treatment clients may instead be simply a collateral result of reduced injection frequency. In this sample of injection drug users, those who continued to inject while in methadone maintenance treatment reported less sharing than users not in methadone maintenance. This relationship persisted after injection frequency and drug-user background characteristics were controlled. Efforts to identify explanatory treatment processes were, however, not successful.

Adult↗
PubMed1993

Trends in self-reported HIV risk behavior: injection drug users in Los Angeles.

This article reviews trends in HIV risk behaviors across serial samples of Los Angeles injection drug users interviewed between 1987 and 1991. All indicators are based on self-reported behavior during the year before the interview. Findings show persistent drug-related risk behaviors. No decrease has occurred in needle sharing with strangers/acquaintances or at shooting galleries. No increase has occurred in self-reported avoidance of needle sharing for as long as 1 year. The only exception to this pattern is a significant increase in bleach use among injection drug users who share needles. Findings are mixed regarding sex-related risk behaviors. Drug users have not reduced their yearly number of sex partners, but condom use has become more prevalent among nonmonogamous drug users. We conclude that preventive education will need to adopt new strategies for addressing persistent risk behaviors while at the same time reinforcing favorable trends that have already begun.

Adult↗
PubMed1992

Alteration by site-directed mutagenesis of the conserved lysine residue in the consensus ATP-binding sequence of the RecB protein of Escherichia coli.

The RecB and RecD subunits of the RecBCD enzyme of Escherichia coli contain amino acid sequences similar to a consensus mononucleotide binding motif found in a large number of other enzymes. We have constructed by site-directed mutagenesis a lysine-to-glutamine mutation in this sequence in the RecB protein. The mutant enzyme (RecB-K29Q-CD) has essentially no nuclease or ATP hydrolysis activity on double-stranded DNA, showing the importance of RecB for unwinding double-stranded DNA. However, ATP hydrolysis stimulated by single-stranded DNA is reduced by only about 5-8-fold compared to the wild-type, nuclease activity on single-stranded DNA is reduced by less than 2-fold, and the nuclease activity of the RecB-K29Q-CD enzyme requires ATP. The effects of the RecB mutation suggest that the RecD protein hydrolyzes ATP and can stimulate the RecBCD enzyme nuclease activity on single-stranded DNA.

Adenosine Triphosphatases↗
PubMed1991

Human immunodeficiency virus glycoprotein (gp120) infused into rat brain induces interleukin 1 to elevate pituitary-adrenal activity and decrease peripheral cellular immune responses.

Intracerebroventricular (i.c.v.) infusion of glycosylated recombinant gp120, the envelope protein of human immunodeficiency virus, in various doses (100 ng to 4 micrograms) resulted in detection of interleukin 1 (IL-1) activity in a high percentage (61%; 33 of 54) of rat brains, whereas IL-1 was very rarely detected in brains of animals infused with several control substances (4%; 1 of 28). To detect IL-1, clarified glial lysate of diencephalon plus brainstem was subjected to gel exclusion chromatography and fractions were assessed for thymocyte stimulation. IL-1 was seen 2, 6, and 24 hr postinfusion. i.c.v. gp120 also produced known effects of IL-1 in brain, elevating steroid concentration in plasma and decreasing cellular immune responses [natural killer (NK) cell activity and mitogenic response to Con A] of blood and splenic lymphocytes. When gp120 was infused together with alpha-melanocyte-stimulating hormone (20 ng), which blocks many biological actions of IL-1, gp120 no longer elevated steroids or decreased NK cell activity. After intravenous gp120, IL-1 was not found in brain or plasma, indicating that stimulation of IL-1 in brain by i.c.v. gp120 was not due to gp120 affecting infiltrating cells from blood or to elevated circulating IL-1. That induction of IL-1 in brain might have resulted from lipopolysaccharide (LPS) in the gp120 solution was ruled out by studies showing that (i) heating of the infusion solution, which does not affect the capacity of LPS to induce IL-1, eliminated the ability of gp120 infusion to induce brain IL-1, and (ii) gp120 induced IL-1 in brains of LPS-resistant C3H/HeJ mice. Injection of gp120 directly into the hippocampus stimulated IL-1 more readily than i.c.v. infusion. Thymocyte stimulation produced by active fractions of gp120-infused brains was blocked by monoclonal antibody to IL-1 receptors. These findings indicate that elevation of IL-1 in brain can result from infection with human immunodeficiency virus and may be responsible for certain abnormalities (e.g., elevated activity of pituitary-adrenal axis) seen in AIDS patients.

Animals↗
PubMed1991

Effect of dithiothreitol on the catalytic activity, quaternary structure and sulfonamide-binding properties of an extracellular carbonic anhydrase from Chlamydomonas reinhardtii.

Extracellular carbonic anhydrase from the unicellular green alga Chlamydomonas reinhardtii is an oligomeric protein containing subunits of 36 and 4 kDa which are joined by disulfide bonds to form higher molecular mass oligomers. In this study, the effect of dithiothreitol on some properties of the enzyme were examined. Dithiothreitol caused a 40% activation of the catalytic activity of the enzyme at low concentrations (0.1 mM), but an inactivation of about 85% of the catalytic activity at high (50 mM) concentrations. Chemical cross-linking of the enzyme with dimethyl suberimidate revealed the existence of oligomers containing up to three large subunits and at least two small subunits. Cross-linking analysis of dithiothreitol-treated carbonic anhydrase revealed that 0.1 mM dithiothreitol had no effect on the subunit composition of the enzyme, but 10 or 50 mM caused subunit dissociation, including the apparent complete dissociation of the small subunits from the large subunits. There was a characteristic enhancement of dansylamide fluorescence when this fluorescent sulfonamide bound carbonic anhydrase and the fluorescence enhancement was retained following the dithiothreitol-induced dissociation of the enzyme. These results indicate that disulfide bonds are essential for maintenance of the oligomeric structure of Chlamydomonas reinhardtii carbonic anhydrase, and that the small subunit may be necessary for enhancing catalysis, but not for the binding of sulfonamides to the enzyme.

Carbonic Anhydrases↗
PubMed1983

Biological assay for zinc availability in wheat germ.

Our objective was to develop a method to determine the bioavailability of zinc in wheat germ. Weanling rats were fed for 10 days a Zn-free diet supplemented with different levels of Zn, with or without 2% wheat germ. Zinc concentrations of either tibia or femurs were plotted directly against Zn added to the diet, giving two lines that were essentially parallel. A multiple regression model was used to obtain a common slope but different intercepts for the lines. The amount of available Zn was calculated by taking the ratio of the difference in intercepts to the common slope. The result showed that wheat germ contained 163.7 micrograms Zn/g, of which 86.7% was bioavailable to the rat.

Animal Feed↗
PubMed1978

Effect of protein A on the antistaphylococcal defence mechanisms of the murine lung.

The importance of IgG attached to protein A in the initial reaction of inspired Staphylococcus aureus and alveolar macrophages was studied by infecting unimmunized mice with aerosols of S. aureus strains 566 and Wood 46 with high and low protein A content. At 2, 4, and 8 hr after infection, the presence of IgG attached to S. aureus and rates of staphylococcal ingestion and killing by macrophages were determined. IgG was detected by staining of sections of the right lung with fluorescein-labeled goat antibody to mouse IgG. For S. aureus strain 566, 25%--40% of the total number of bacteria, as determined in equivalently sized subjacent sections stained by the Brown and Brenn tissue gram stain, contained attached IgG. A few S. aureus strain Wood 46 were surrounded by dimly fluorescing complexes. Since rates of bacterial ingestion and killing were similar for both strains in this in vivo model of infection, IgG binding to protein A does not affect the bactericidal capacity of alveolar macrophages.

Animals↗