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Biomedical subjects

S Short

Publications and source records attributed to S Short.

At least 37 records · Page 2Linked to original sources
PubMed1996

Intracellular location of cysteine transport activity correlates with productive processing of antigen disulfide.

Activation of CD4+ T cells requires processing of exogenous protein antigens by antigen-presenting cells (APC). A macrophage hybridoma and B cell lymphoma were comparable in their ability to process hen egg lysozyme (HEL), which involves reduction of its disulfide bonds. The intracellular levels of cysteine and glutathione, major physiological thiols, based on protein content were similar within these cell lines. In addition, the cysteine transport pathway in viable cells was assessed by 35S-cystine uptake. For macrophages, the majority of the radioactivity resided in high density subcellular fractions of Percoll gradients that comigrated with lysosomal beta-galactosidase (beta-gal). Besides the lysosomes, low density fractions cosedimenting with endosomes incorporated the radiolabel in the B cells. Both peaks of radioactivity disappeared when the B cells were incubated with unlabeled carboxymethyl-cysteine (CM-cysteine), a specific competitor of the plasma membrane CG transport system. The distinct gradient profiles of radiolabel uptake in the cells correlated with a difference in their capacity to process the transferrin-lysozyme conjugate (TF-HEL). TF-HEL was significantly more stimulatory than HEL in inducing a HEL-specific T cell response with the B cells as the APC. However, the potencies of TF-HEL and HEL were similar when the macrophages were the APC. Thus, the intracellular location of cysteine transport activity may be cell lineage-dependent, and its presence may, in part, determine whether an organelle is a productive site of processing antigens with disulfide bonds that is necessary for CD4+ cell activation.

Antigen Presentation↗
PubMed1996

Defective antigen processing correlates with a low level of intracellular glutathione.

Previously, we reported that Chinese hamster ovary (CHO) cells transfected with murine mouse major histocompatibility complex class II genes, exhibit a unique antigen (Ag) processing defect whereby these cells are impaired in processing only Ag with disulfide bonds. Here, we examined various aspects of the intracellular reducing environment in the CHO cells to understand the underlying mechanism causing the defect. A cell hybrid generated by the fusion of CHO cells and L cell fibroblasts was used for comparison due to their competency in processing Ag. The transport pathway of cysteine within the CHO cells appeared normal. However, these cells had a significantly lower level of glutathione, a major physiological reducing thiol, compared to the cell hybrid. Treatment of the CHO cells with N-acetyl-L-cysteine did not augment their glutathione content nor their ability to process Ag. When the cell hybrid was treated with L-buthionine-(S,R)-sulfoximine (BSO), which significantly decreased their glutathione level, the hybrid poorly processed hen egg lysozyme (HEL) and ovalbumin, which have disulfide bonds. In contrast, BSO treatment did not affect the capacity of the hybrid to process pigeon cytochrome c and carboxymethylated HEL, which lack disulfide bonds. Therefore, low intracellular glutathione levels in antigen-presenting cells correlated with defective processing of Ag with disulfide bonds, indicating that this thiol may be a critical factor in regulating productive Ag processing.

Acetylcysteine↗
PubMed1996

Palliation of symptomatic adrenal gland metastases by radiotherapy.

Whilst adrenal metastases are common in patients with metastatic disease, they are rarely symptomatic. We present a series of seven patients with painful adrenal metastases who were seen in one centre over an 18-month period. All responded to palliative radiotherapy with a reduction in pain.

Adrenal Gland Neoplasms↗
PubMed1995

A newly described possible complication of lymphangioma circumscriptum.

Lymphangioma circumscriptum is a rare disorder of lymphatic channels, the cause of which is poorly understood. It is an unpleasant, but benign, condition conventionally managed by wide local excision, which provides symptom control and often prevents recurrence. No long term complications and no association with squamous cell carcinoma have been previously documented. We present a 20-year-old patient with lymphangioma circumscriptum involving the vulval and perianal areas, which recurred after surgery and seems to have predisposed to squamous cell carcinoma 11 years after presentation.

Adult↗
PubMed1995

Identification of a silencer module which selectively represses cyclic AMP-responsive element-dependent gene expression.

The cyclic AMP (cAMP)-inducible promoter from the rat lactate dehydrogenase A subunit gene (LDH A) is associated with a distal negative regulatory element (LDH-NRE) that represses inherent basal and cAMP-inducible promoter activity. The element is of dyad symmetry, consisting of a palindromic sequence with two half-sites, 5'-TCTTG-3'. It represses the expression of an LDH A/chloramphenicol acetyltransferase (CAT) reporter gene in a dose-dependent, orientation- and position-independent fashion, suggesting that it is a true silencer element. Uniquely, it selectively represses cAMP-responsive element (CRE)-dependent transcription but has no effect on promoters lacking a CRE sequence. The repressing action of LDH-NRE could be overcome by cotransfection with LDH A/CAT vector oligonucleotides containing either the LDH-NRE or CRE sequence. This suggests that the reversal of repression was caused by the removal of functional active, limiting transacting factors which associate with LDH-NRE as well as with CRE. Gel mobility shift, footprinting, and Southwestern blotting assays demonstrated the presence of a 69-kDa protein with specific binding activity for LDH-NRE. Additionally, gel supershift assays with anti-CREB and anti-Fos antibodies indicate the presence of CREB and Fos or antigenically closely related proteins with the LDH-NRE/protein complex. We suggest that the LDH-NRE and CRE modules functionally interact to achieve negative modulation of cAMP-responsive LDH A transcriptional activity.

Animals↗
PubMed1995

Role of TNF alpha in the induction of antigen induced arthritis in the rabbit and the anti-arthritic effect of species specific TNF alpha neutralising monoclonal antibodies.

OBJECTIVE: To investigate the role of tumour necrosis factor alpha (TNF alpha) in the development of antigen induced arthritis (AIA) in rabbits. METHODS: Monoclonal antibodies to rabbit TNF alpha were developed in rats and were used to detect TNF alpha in synovial fluid by enzyme linked immunosorbent assay and to localise it in tissue sections of synovium and cartilage from rabbits up to 21 days after induction of AIA. An antibody which neutralised TNF alpha activity in vitro was injected into rabbits to block TNF alpha action in vivo in AIA. Joint swelling, leucocyte infiltration into synovium and proteoglycan loss from cartilage were measured and compared with a control group, which were injected with sterile saline. RESULTS: Monoclonal antibodies to purified rabbit TNF alpha were prepared in rats and two were selected which were able to neutralise rabbit TNF alpha in a cytotoxicity bioassay. TNF alpha was detected in significant concentrations (21.7 (SE 0.5) pg/ml) in the arthritic joint fluid of rabbits with AIA only at one day after induction and it was then also sparsely localised in cells of the synovium, but from day 3 onwards it was localised more strongly in the deep zone of articular cartilage. Injection of anti-TNF monoclonal antibody R6 over three days into rabbits with AIA reduced joint swelling and leucocyte infiltration into joint fluid and decreased the expression of CD11b and CD18 on cells in the joint fluid. However, there was no significant reduction in the loss of proteoglycan from articular cartilage, although the joint fluid at three days contained a lower glycosaminoglycan content. The antibody R6 gave most effect at a dose of 0.6 mg/kg and there was no increase in its effectiveness at a fivefold greater dose (3.0 mg/kg). Treatment over 10 days gave a more complete suppression of joint swelling, but did not result in any less proteoglycan loss from cartilage. Treatment for five days with a 16 day follow up gave a significant reduction in swelling for several days beyond the treatment, but the swelling then slowly returned, until by day 21 there was no significant difference in joint swelling and there was also no recovery of cartilage proteoglycan content. A rabbit anti-rat immunoglobulin response was detected at 21 days, which may have limited the long term effectiveness of the antibody. CONCLUSIONS: In AIA in rabbits, TNF alpha was only detected in synovial fluid at one day after induction and there was only limited cellular localisation of TNF alpha in synovium and cartilage from three days. However, neutralising TNF alpha with a monoclonal antibody was effective in suppressing inflammatory changes in the joint during the acute onset of AIA, but it had little effect on the loss of proteoglycan from cartilage. The results suggest that blocking inflammation and synovitis with anti-TNF alpha may be more easily achieved than preventing damage to articular cartilage.

Animals↗
PubMed1994

Analysis of the rat lactate dehydrogenase A subunit gene promoter/regulatory region.

The rat lactate dehydrogenase (LDH) A subunit gene promoter contains a putative AP-1 binding site at -295/-289 bp, two consensus Sp1 binding sites at -141/-136 bp and -103/-98 bp, and a single copy of a consensus cyclic AMP-responsive element (CRE) at -48 to -41 bp upstream of the transcription initiation site. Additionally, an as yet unidentified silencer element is located within the -1173/-830 bp 5'-flanking region. Transient transfection analyses of a -1173/+25 bp LDH A-chLoramphenicol acetyltransferase fusion gene has indicated a complete inability of the promoter fragment to direct basal or forskolin-induced transcription. Deletion of the -1173/-830 bp sequence restored basal and cyclic AMP (cAMP)-inducible activity. Point mutations in the Sp1 binding sites of a -830/+25 bp promoter fragment reduced basal but not the relative degree of cAMP-inducible activity. cAMP-regulated transcriptional activity was dependent upon an 8 bp CRE, -TGACGTCA-, located at the -48/-41 bp upstream region. Mutations in the CRE abolished cAMP-mediated induction and reduced basal activity by about 65%. The CRE binds a 47 kDa protein which has previously been identified as CRE binding protein (CREB)-327, an isoform of the activating transcription factor/CREB transcription factor gene family. Co-transfection of a vector that expresses the catalytic subunit of cAMP-dependent protein kinase stimulates LDH A subunit promoter activity suggesting that cAMP induces LDH A subunit gene expression through phosphorylative modification of CREB-327. This study emphasizes a fundamental role of several modules including Sp1 and CREB binding sites in regulating basal and cAMP-mediated transcriptional activity of the LDH A gene.

Animals↗
PubMed1993

Verification of the Acute Physiology and Chronic Health Evaluation scoring system in a Hong Kong intensive care unit.

OBJECTIVES: To validate the Acute Physiology and Chronic Health Evaluation (APACHE II) severity of illness scoring system in Chinese patients in a multidisciplinary intensive care unit (ICU) in Hong Kong. To audit the service and utilization of an ICU with a low ICU to hospital bed ratio. DESIGN: Prospective data collection and review. SETTING: A 12-bed multidisciplinary ICU within a 1,430-bed tertiary care university hospital. PATIENTS: Data from 1,573 of 1,814 consecutive patients admitted to the ICU from May 1988 to November 1990 were studied. The patients were all Chinese. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: The patients' clinical details and APACHE II scores were recorded on day 2 of admission and reviewed at hospital discharge or after death. The APACHE II scores, risk of death values, age, and length of ICU stay between survivors and nonsurvivors were compared by two-sample t-tests. Relationships between mortality and APACHE II score, risk of death, and results from previous studies were investigated using the Pearson product-moment coefficient and regression analysis. Predictive capacity of risk of death was assessed by receiver operating characteristic curve analysis. The hospital mortality rate for study patients was 36%. Survivors were younger, had shorter ICU stays, lower APACHE scores, and lower risk of death values than nonsurvivors (p < .001). There was close correlation (r2 = .81, .77, and .76 for all patients, operative group, nonoperative group, respectively) between APACHE II scores and predicted risk of death values. Risk of death was an accurate group predictor of death in all patients and in separate operative and nonoperative groups. Areas under the receiver operating characteristic curves were 0.89 (all patients), 0.85 (operative), and 0.88 (nonoperative). Neither the Apache II scores nor risk of death scores were sufficiently accurate to predict outcome of individual patients. There was close concordance between observed and predicted mortality of patient groups. Mortality ratio was 0.97 (all patients), 0.89 (operative group), and 1.02 (nonoperative group). Chronological age, per se, was not a good predictor of mortality. The audit of the ICU service showed a short length (4.2 days) of ICU stay and high bed occupancy (80%). Subgroups of low-risk, postoperative patients with good outcomes and poor-risk patients admitted after cardiopulmonary arrest with a high mortality rate were identified. CONCLUSIONS: The APACHE II scoring system was an accurate predictor of group outcome in a Chinese population, making it suitable for comparisons between countries. Application of the APACHE II scoring system in a clinical audit facilitates critical appraisal of an ICU service. Problems identified by the study were a shortage of ICU beds and delayed referrals of patients.

Adult↗
PubMed1991

Functional analysis of cis- and trans-regulatory elements of the lactate dehydrogenase A subunit promoter by in vitro transcription.

Using a transcription system from nuclear extracts of rat C6 glioma cells we have investigated the mechanism by which transcription from the lactate dehydrogenase A subunit (LDH) promoter is regulated via the cAMP-activated pathway. We demonstrated that the system accurately initiates transcription from the LDH promoter. Analysis of the competitive effects of linker-scanning mutants showed that the wild-type LDH promoter exhibited the highest competitive effect and reduced the rate of basal transcription, whereas LDH promoter fragments with a mutated cAMP-responsive element had little competitive activity. Cyclic AMP and the catalytic subunit of cAMP-dependent protein kinase stimulated the rate of transcription from the wild-type promoter, an effect which was inhibited by the catalytic subunit inhibitor protein. A beta-galactosidase-cAMP-responsive element binding protein fusion protein had no effect on the basal rate of transcription. Addition of beta-galactosidase-cAMP-responsive element binding protein together with cAMP or the catalytic subunit, however, enhanced the rate of transcription. The demonstrated regulatory effects indicate that the sensitivity of the transcription system makes it suitable for the functional analysis of homologous LDH and possibly heterologous transcription regulatory elements.

Animals↗
PubMed1991

Calcitonin gene-related peptide in the developing and aging thymus. An immunocytochemical study.

Calcitonin gene-related peptide (CGRP) is known to block Con A and PHA induced T cell proliferation. As a first step in determining the role of this peptide in T cell education and function we have studied the distribution of CGRP within the developing mouse thymus using immunocytochemistry. CGRP-like immunoreactivity (CGRP-IR) was found in the thymic nerves in close proximity to blood vessels in the 17-day-old embryonic mouse thymus. A discrete population of small cells at the cortico-medullary junction also stained intensely for CGRP. As the mouse thymus reached maturity (three to eight weeks) CGRP innervation became more dense, with fibers running along the vasculature at the cortico-medullary boundary, then branching into the cortical and medullary regions. Some fibers were invested in the blood vessels while a large portion formed varicosities among the cells of the thymus. In the mature thymus, the small CGRP-IR cortico-medullary cells were more numerous, and CGRP-IR was also found in subcapsular and trabecular mast cells. The pattern of innervation remained the same in the aging mouse thymus (six months), but there appeared to be somewhat fewer cortico-medullary cells and an increase in mast cell number. In the aged (eighteen months) thymus, the small CGRP-IR cortico-medullary cells were rarely seen, but mast cells were more numerous, most of which stained positively for CGRP, in the connective tissue. Nerves containing CGRP-IR generally had the same distribution as in the younger mice but appeared somewhat truncated. The distribution of CGRP-IR nerves in the mouse thymus at different stages of development was similar to that reported for cholinergic (AChE-positive) nerves. Since the brain-stem vagal nuclei have been shown by retrograde transport studies to project to the thymus as well as to contain CGRP-IR neurons, our findings suggest that CGRP-IR thymic nerves may be derived from the vagus complex.

Aging↗
PubMed1990

Oligohydramnios sequence and renal tubular malformation associated with maternal enalapril use.

We present the case of a child who died of pulmonary hypoplasia as a result of the oligohydramnios sequence. The mother was taking enalapril, as well as propranolol and hydrochlorothiazide, for treatment of hypertension associated with systemic lupus erythematosus. Autopsy examination revealed severe renal tubular malformation. Correlation of animal data with previous case reports of neonatal anuria in association with maternal angiotensin converting enzyme inhibitors suggests that these agents may have a deleterious effect on fetal renal development and general well-being.

Amniotic Fluid↗
PubMed1989

Determination of selenium in human blood by high-performance liquid chromatography with fluorescence detection.

Selenium was determined in human whole blood or red cells by high-performance liquid chromatography (HPLC) using a new internal standard. The method provides a 0.15-ng detection limit, a between-day standard deviation of 1% at the 20-ng level, and a 3% within-day standard deviation at the 1-ng level. Samples were wet-ashed, and a selenium-diaminonaphthalene derivative was formed, followed by addition of tetraphenylnaphthacene internal standard, reverse-phase HPLC separation (10 min/run), and fluorescence detection. The detection limit was reduced by discrimination of fluorescence excitation of the selenium complex from the background using long-wavelength excitation (480 nm), removal of stray light in the excitation beam, and other optimizations described. Representative aliquots of frozen and thawed whole blood samples were obtained by using a nitric acid predigestion at ambient temperature. Procedures to validate the method included standard addition and neutron activation analysis.

Chromatography, High Pressure Liquid↗
PubMed1988

The effects of shift work on nurses: implications for Australian hospitals.

This review of Australian and international research on the effects of shift work on nurses reveals that there is neither a wide nor a growing body of information on shift work in nursing. Shift work in nursing has been the subject of only three substantial studies overseas, and none in Australia. Although research indicates that there are negative physiological, psychological and social consequences associated with shift work, it is not possible at the current time to favour any single shift or roster system, particularly in nursing where empirical research is wanting.

Australia↗
PubMed1986

Comparison of plasma alpha and gamma tocopherol levels following chronic oral administration of either all-rac-alpha-tocopheryl acetate or RRR-alpha-tocopheryl acetate in normal adult male subjects.

Vitamin E was administered orally (400 IU twice a day) to adult male humans for 28 days as either dl-alpha-tocopheryl acetate (all-rac-alpha-tocopheryl acetate) or d-alpha-tocopheryl acetate (RRR-alpha-tocopheryl acetate). Plasma alpha-tocopherol rose rapidly and fell at the same rate following cessation of supplementation with both forms of vitamin E. No significant differences in plasma alpha- or gamma-tocopherol levels were found between the two forms of vitamin E following their administration. The results confirm the currently accepted biopotencies of 1.0 IU/mg and 1.36 IU/mg, respectively for the two forms of vitamin E. Supplementation with either form of alpha-tocopheryl acetate resulted in depressing plasma gamma-tocopherol to less than 1/3 of initial levels; also the gamma/alpha ratio was depressed to less than 1/7 of the initial value. The study suggests that the gamma/alpha vitamin E ratio might also serve as a sensitive index of alpha-tocopherol ingestion.

Administration, Oral↗