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Biomedical subjects

D Slater

Publications and source records attributed to D Slater.

At least 19 recordsLinked to original sources
PubMed2004

Primary B-cell lymphoma of the skin: the Sheffield Lymphoma Group Experience (1984-2003).

The clinical presentation, treatment and outcome were retrospectively evaluated in a series of 66 patients with primary B-cell lymphoma of the skin, referred to the Sheffield lymphoma group (SLG) between 1984 and 2003. This is the largest series reported from the UK. The lymphoma database was searched and clinical records were reviewed. Absence of any detectable extracutaneous lesion and the expression of B-cell restricted antigens by neoplastic cells were the essential criteria for selection of cases. The cohort included 37 (56%) males and 29 (44%) females with a mean age of 59 years. The most commonly involved site was the trunk and the disorder typically showed non-aggressive clinical behaviour; the majority of the patients presented with stage I (82%) disease with a tendency to remain localised to a limited area of the skin. Follicular lymphoma was the most common histologic subtype (35%), the next most frequent was the diffuse large cell lymphoma (32%) whereas marginal zone lymphoma constituted 15%. The majority (47%) of patients were treated with radiotherapy for localised disease whereas chemotherapy was given in 20% of patients, with single agent chlorambucil being most frequently used. Surgical excision as the sole modality of treatment was adequate in 33%. Disease-free survival (DFS) was 91% at 1 year, 82% at 2 years and 60% at 5 years. DFS was significantly lower with older age (>45 years), leg lesions, generalised and multiple lesions, and for those treated with chemotherapy. The survival at 5 and 10 years was 80%. The histologic grade, leg involvement and the number of lesions were the most significant variables affecting overall survival. Only 7 patients died of lymphoma. In conclusion, primary cutaneous B-cell lymphoma represents a specific entity concerning clinical behaviour, response to treatment, and overall prognosis.

Adolescent↗
PubMed2001

Characterization of an antibody to the human melatonin mt1 receptor.

Melatonin acts via high affinity, G-protein coupled, seven transmembrane domain receptors. To precisely localize these receptors, antibodies were raised in chickens against a 15 amino acid fragment at the intracellular C-terminal region of the human melatonin receptor subtype mt1 (DSSNDVADRVKWKPS, mt(1338-352)). A chimeric form of the receptor with a hydrophilic Flag peptide (DYKDDDDK) in sequence with the extracellular N-terminus (Flag-mt1) was generated by polymerase chain reaction and expressed in mammalian cell lines. An IgY antibody (Y31), which gave high antibody titres by enzyme-linked immunosorbent assay, was used to localize Flag-mt1 in stably transfected cells by immunofluoresence. Flag-mt1 localization with Y31 was identical to that obtained with the M5 antibody directed against the Flag epitope and was mainly localized to the Golgi apparatus with some staining at the cell surface. No staining was seen in untransfected cells with either antibody. Y31 staining was abolished using antibody preabsorbed with peptide antigen. Y31 immunofluorescence in fetal human kidney sections was restricted to nephrogenic regions and matched that of 2-((125)I)iodomelatonin binding and mt1 gene expression by in situ hybridization. Y31 was used to immunoprecipitate biotinylated membrane proteins from Flag-mt1 stably transfected and untransfected CHO cells. Western blotting of immunoprecipitated proteins revealed two major bands specific to stably transfected cells, one at 63 kDa and one at 86 kDa. The first band almost certainly corresponds to the glycosylated form of Flag-mt1 and the second band to receptor dimers. Thus, Y31 antibody is suitable for use in detecting the human mt1 receptor subtype in tissues and in transfected cells.

Amino Acid Sequence↗
PubMed2001

The changing character of regulation: a comparison of Europe and the United States.

European and U.S. regulatory policies have changed considerably over the past 30 years. In Europe, since the mid-1980s, consumer and environmental regulation has become more politically salient and regulations have by and large become stricter. On the other hand, in the United States consumer and environmental issues have become less salient and contentious, and regulations have not become (comparatively) stricter. This apparent "flip-flop" of regulatory systems has not been analyzed in much detail to date. This perspective is an attempt to analyze some examples in which it has occurred and identifies one possible cause--namely, credibility.

Journal Article↗
PubMed2001

Oxytocin antagonists: clinical and scientific considerations.

Preterm delivery is the largest cause of perinatal mortality and morbidity, yet the treatment of preterm labour has not been demonstrated to improve outcome. The reasons are numerous and complex, but they include a failure to understand the mechanism(s) of preterm labour, the multitude of different causes, the difficulty in diagnosis and the problems of outcome measurement in clinical trials. Recently, an oxytocin antagonist (atosiban) has been introduced into clinical practice in Europe. Although it may be an effective tocolytic, a beneficial effect on perinatal outcome has not been demonstrated. Atosiban has an effect at both oxytocin and vasopressin (V(1a)) receptors, which (assuming efficacy) raises the question as to whether oxytocin or vasopressin V(1a) antagonism is required for tocolysis. This review examines the rationale for tocolysis in preterm labour, the evidence for administration of atosiban and the role for oxytocin, vasopressin and their receptors in the onset of labour. Experimental Physiology (2001) 86.2, 297-302.

Female↗
PubMed2001

Model acquisition and invariant tracking of unknown materials in hyperspectral images.

We consider the problem of acquiring models for unknown materials in airborne 0.4-2.5 microm hyperspectral imagery and using these models to identify the unknown materials in image data obtained under significantly different conditions. The material models are generated with use of an airborne sensor spectrum measured under unknown conditions and a physical model for spectral variability. For computational efficiency, the material models are represented by using low-dimensional spectral subspaces. We demonstrate the effectiveness of the material models by using a set of material tracking experiments in HYDICE images acquired in forest and desert environments over widely varying conditions. We show that techniques based on the new representation significantly outperform methods based on direct spectral matching.

Journal Article↗
PubMed2001

Expression of cyclooxygenase enzymes in rat hypothalamo-pituitary-adrenal axis: effects of endotoxin and glucocorticoids.

Prostaglandins play a key role in mediating the hypothalamo-pituitary-adrenocortical (HPA) responses to immune insults. This study aimed to provide some insight into the relative contributions of the constitutive and inducible forms of cyclooxygenase (COX-1 and COX-2) to the generation of these prostanoids by examining the effects of (1) endotoxin treatment on the expression of COX-1 and COX-2 mRNAs in the various components of the HPA axis in control and glucocorticoid pretreated rats, and (2) selective inhibition of COX-2 on the production of corticosterone by adrenal tissue in vitro. Endotoxin caused a marked rise in COX-2 mRNA in the adrenal gland that was evident 3 and 6 h after the injection and was prevented by pretreatment with dexamethasone. It also induced a modest increase in COX-2 mRNA in the hypothalamus but not in the hippocampus or anterior pituitary gland. By contrast, COX-1 mRNA was largely unaffected by the drug treatments in all tissues studied. In vitro the selective COX-2 inhibitor SC-236 caused a marked reduction in adrenocorticotropic hormone-driven corticosterone release, as did the nonselective COX inhibitor, indomethacin. These results support a role of COX-2 in the manifestation of the HPA responses to endotoxin, particularly within the adrenal gland.

Animals↗
PubMed2000

Mutant torsinA, responsible for early-onset torsion dystonia, forms membrane inclusions in cultured neural cells.

Early-onset torsion dystonia is a hereditary movement disorder thought to be caused by decreased release of dopamine into the basal ganglia, without apparent neuronal degeneration. Recent cloning of the gene responsible for this disease, TOR1A (DYT1), identified the encoded protein, torsinA, as a member of the AAA+ superfamily of chaperone proteins and revealed highest levels of expression in dopaminergic neurons in human brain. Most cases of this disease are caused by a deletion of one glutamic acid residue in the C-terminal region of the protein. Antibodies generated against torsinA revealed expression of a predominant immunoreactive protein species similar to the predicted size of 37.8 kDa in neural, glial and fibroblastic lines by western blot analysis. This protein is N-glycosylated with high mannose content and not, apparently, phosphoryl-ated. Overexpression of torsinA in mouse neural CAD cells followed by immunocytochemistry, revealed a dramatically different pattern of distribution for wild-type and mutant forms of the protein. The wild-type protein was found throughout the cytoplasm and neurites with a high degree of co-localization with the endoplasmic reticulum (ER) marker, protein disulfide isomerase. In contrast, the mutant protein accumulated in multiple, large inclusions in the cytoplasm around the nucleus. These inclusions were composed of membrane whorls, apparently derived from the ER. If disrupted processing of the mutant protein leads to its accumulation in multilayer membranous structures in vivo, these may interfere with membrane trafficking in neurons.

Animals↗
PubMed1999

Leptin receptor and neuropeptide Y gene expression in the sheep brain.

Leptin, a protein secretory product of adipocytes, is important in appetite control, energy balance and reproduction. In rodents, the physiological effects of leptin are centrally mediated, in part via the neuropeptide Y (NPY) system in the hypothalamus. The role of leptin in ruminants, where appropriate nutrition and reproductive status are of major economic concern, is largely unknown. To elucidate the function of leptin in sheep we have investigated putative sites of action for leptin in the brain and pituitary gland using both in-situ hybridization to detect expression of the signalling form of the leptin receptor (OB-Rb) and in-vitro autoradiography using (125I)leptin to detect sites of specific leptin binding. OB-Rb gene expression occurred in the hippocampus, cerebral cortex, preoptic area, stria terminalis and choroid plexus, and within the hypothalamus in the paraventricular (PVN), ventromedial (VHM) and arcuate (ARC) nuclei. OB-Rb gene expression in the ovine pituitary gland was not detected by in-situ hybridization. Sites of OB-Rb and NPY gene expression were compared using both in-situ hybridization on adjacent sections containing the arcuate and ventromedial nuclei, and dual in-situ hybridization on sections containing these areas. In serial sections, OB-Rb expression was found to correspond closely with that of NPY over the arcuate nuclei. Using dual in-situ hybridization, NPY expressing neurones in the arcuate nuclei were also positive for OB-Rb gene expression. Therefore, it appears that leptin may partly act via OB-Rb located on NPY neurones in the sheep hypothalamus as in the rodent.

Animals↗
PubMed1999

Expression of cyclo-oxygenase types-1 and -2 in human fetal membranes throughout pregnancy.

Human labour is associated with increased prostaglandin synthesis within the fetal membranes. We have studied the expression of the two isoforms of the central prostaglandin synthetic enzyme, cyclo-oxygenase (COX-1 and COX-2), in human fetal membranes throughout pregnancy, at mRNA, protein and activity levels. COX-1 mRNA expression was low in human amnion and chorion-decidua and did not change with gestational age. COX-2 mRNA expression in fetal membranes increased with gestational age, with significant up-regulation prior to the onset of labour and in association with labour. Protein concentrations of COX-1 did not change, whilst concentrations of COX-2 increased from the first to the third trimester. COX activity increased with gestational age and in association with labour, although prostaglandin production in fetal membranes collected after labour was reduced, suggesting reduced substrate supply. These data suggest that it is up-regulation of COX-2, rather than of COX-1, which mediates increased prostaglandin synthesis within the fetal membranes at term. Much of the increase in COX-2 expression precedes the onset of labour, suggesting that it is a cause, rather than a consequence, of labour.

Amnion↗
PubMed1998

Changes in the expression of the type-2 but not the type-1 cyclo-oxygenase enzyme in chorion-decidua with the onset of labour.

OBJECTIVE: To determine the relative expression of cyclo-oxygenase (COX)-1 and COX-2 in the chorion-decidual part of human fetal membranes following delivery at term and to identify any changes in expression associated with labour. METHODS: Fetal membranes were collected from 12 term pregnancies before labour following elective caesarean section and from 12 spontaneous vaginal deliveries. Expression of COX-1 and COX-2 mRNA was measured using a previously validated quantitative RT-PCR assay. RESULTS: COX-2 expression exceeded that of COX-1 by approximately eight-fold. COX-1 expression did not change but COX-2 expression was found to increase four-fold with labour. CONCLUSIONS: Chorion-decidua has the capacity to contribute to the increase in prostaglandin synthesis within the uterus associated with labour. As in the amnion, it is COX-2 and not COX-1 which is upregulated with labour. COX-2 selective anti-prostaglandins should therefore be as effective as nonselective drugs in inhibition of fetal membrane prostaglandin synthesis.

Cesarean Section↗