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J Hsuan

Publications and source records attributed to J Hsuan.

25 records · Page 2Linked to original sources
PubMed1991

Characterization of two 85 kd proteins that associate with receptor tyrosine kinases, middle-T/pp60c-src complexes, and PI3-kinase.

Affinity-purified bovine brain phosphatidylinositol 3-kinase (PI3-kinase) contains two major proteins of 85 and 110 kd. Amino acid sequence analysis and cDNA cloning reveals two related 85 kd proteins (p85 alpha and p85 beta), which both contain one SH3 and two SH2 regions (src homology regions). When expressed, these 85 kd proteins bind to and are substrates for tyrosine-phosphorylated receptor kinases and the polyoma virus middle-T antigen/pp60c-src complex, but lack PI3-kinase activity. However, an antiserum raised against p85 beta immunoprecipitates PI3-kinase activity. The active PI3-kinase complex containing p85 alpha or p85 beta and the 110 kd protein binds to PDGF but not EGF receptors. p85 alpha and p85 beta may mediate specific PI3-kinase interactions with a subset of tyrosine kinases.

Animals↗
PubMed1990

Expression of epidermal-growth-factor receptor in the K562 cell line by transfection. Altered receptor biochemistry.

The epidermal-growth-factor (EGF) receptor was expressed in the human erythroleukaemic cell line K562 by transfection of the receptor cDNA. EGF-receptor biochemistry appears altered in the K562 transfectants. Autophosphorylation of the K562 receptor is not stimulated substantially by EGF. Tyrosine kinase activity of the receptor is high in the absence of EGF, whereas receptor affinity for EGF is low. K562 cells are shown to lack mRNA for transforming growth factor alpha (TGF alpha). Therefore autocrine stimulation of the K562 receptor, at least by TGF alpha, does not explain the observed receptor biochemistry. The K562 receptor is phosphorylated at a single major site in intact cells, a threonine residue that may be Thr-669. Possible mechanisms of regulation of the EGF receptor in the K562 transfectants are discussed.

DNA↗
PubMed1990

A novel neutrophil chemoattractant generated during an inflammatory reaction in the rabbit peritoneal cavity in vivo. Purification, partial amino acid sequence and structural relationship to interleukin 8.

An inflammatory reaction was induced in vivo by injection of zymosan into the peritoneal cavity of the rabbit. The inflammatory exudate was found to contain oedema-inducing and neutrophil chemoattractant activity when assayed in rabbit skin in vivo, using 125I-albumin and 111In-neutrophils. This activity was additional to that of complement fragment C5a, which was removed by an affinity gel. Two chemoattractants were isolated by cation-exchange, gel-filtration and reversed-phase h.p.l.c. One of these, which ran as a single band of 6-8 kDa on SDS/PAGE, was subjected to N-terminal sequence analysis without reduction and alkylation of cysteine residues. Positive identification of 28 of the first 31 amino acids revealed a rabbit homologue of interleukin-8 (75% sequence identity with human interleukin-8). The demonstration of interleukin-8 as a major neutrophil chemoattractant in an inflammatory reaction in vivo provides the basis for further investigations into the role of this cytokine in the inflammatory process.

Amino Acid Sequence↗
PubMed1990

Proteolytic activation of protein kinase C-epsilon.

Proteolysis of native protein kinase C-epsilon (PKC-epsilon) is shown to occur through tryptic attack at multiple sites within the PKC-epsilon V2/V3 domain. Following initial cleavage of PKC-epsilon with trypsin, the kinase activity using a synthetic peptide substrate was found to be lipid/phorbol-ester independent, as observed for other members of this kinase family. Interestingly, there is also an increase in the histone kinase activity, indicating that there is an influence of the regulatory domain of the enzyme on substrate specificity. This is discussed in the context of alternatively spliced PKC-epsilon mRNAs that are shown to be present in brain and lung tissues.

Amino Acid Sequence↗
PubMedDate not supplied

Idiopathic sclerosing inflammation of the orbit: a case of steroid-responsive disease in a patient with auto-immune hemolytic anemia.

PURPOSE: Idiopathic sclerosing orbital inflammation (ISOI) has been categorized by some authors as a unique clinicopathologic entity, separate from the heterogeneous group of disorders known collectively as nonspecific orbital inflammation. Histologic similarity and clinical association with other fibrosclerosing conditions has been shown. The authors present a case of ISOI in conjunction with autoimmune hemolytic anemia. METHODS: A 59-year-old woman with a history of hemolytic anemia had left upper lid swelling, periocular pain, proptosis, and restriction of ocular motility. Magnetic resonance imaging (MRI) showed a homogeneously enhancing lateral orbital mass. Biopsy revealed dense fibrous connective tissue with a paucicellular infiltrate, consistent with ISOI, and treatment with prednisolone 60 mg/day was instituted. RESULTS: At 4-week review, the proptosis had settled and the patient regained full range of extraocular movements. At 14 months, the response was sustained and repeat MRI showed a 70% reduction in size of the mass. CONCLUSIONS: The first known case of ISOI and hemolytic anemia is presented. Despite dense fibrosis histologically, steroid responsiveness can be encountered in cases of ISOI. An early, aggressive approach to management is recommended, and corticosteroids should be considered as a treatment option.

Anemia, Hemolytic, Autoimmune↗
PubMedDate not supplied

Infectious keratitis in South Australia: emerging resistance to cephazolin.

PURPOSE: To analyze the microbiologic spectrum and patterns of resistance of infectious keratitis in patients treated at a tertiary hospital in South Australia. METHODS: Retrospective review of microbiology laboratory records of all patients with infectious keratitis who had corneal scrapings, from 1998 to 2003. All records were subsequently reviewed for Gram staining and culture results, as well as antibiotic sensitivity and resistance. RESULTS: Positive corneal cultures were obtained in 134 out of 211 patients who had corneal scrapings (63.5%). Coagulase negative Staphylococcus was the commonest pathogen identified (29.8% of positive cultures), followed by Staphylococcus aureus (18.7%), Pseudomonas aeruginosa (12.7%), Moraxella (6.7%), Streptococcus pneumonia (6.0%), and fungal keratitis (5.2%). In 43.3% of culture positive cases, the organisms were also identified in Gram stain, and in all these cases there was a full correlation between the two methods. In vitro sensitivities were highest for gentamicin. Fourteen cases (35%) of coagulase negative Staphylococcus were found to be resistant to cephazolin. No ciprofloxacin resistance was identified in all Pseudomonas isolates tested. CONCLUSIONS: Staphylococcus species continue to be the commonest causative organism for infectious keratitis; however, there is an emerging resistance to cephazolin, which is commonly used as the first-line antibiotic for Gram-positive cocci.

Adolescent↗