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S Sharp

Publications and source records attributed to S Sharp.

At least 37 records · Page 2Linked to original sources

Neurone-specific enolase and Sangtec 100 assays during cardiac surgery: Part I--The effects of heparin, protamine and propofol.

Neurone-specific enolase (NSE) and Sangtec 100 (S-100) (Sangtec Medical, Sweden) assays are designed for clotted samples, but when studying cerebral damage following cardiac surgery, perioperative samples will contain heparin and/or protamine. The lipid emulsion propofol is also frequently used during cardiac surgery and could affect the assays. We, therefore, studied the effects of heparin, protamine and propofol on the accuracy of NSE and S-100 assays in five healthy patients. Blood samples were taken and divided into four groups: normal saline was added to group A; heparin to group B; heparin followed by protamine to group C; and propofol to group D. NSE and S-100 concentrations were measured for all samples. Neither heparin, protamine nor propofol affected the accuracy of S-100 and NSE assays; therefore, samples can be taken throughout operations involving cardiopulmonary bypass without influencing the results.

Anesthetics, Intravenous↗

Neurone-specific enolase and Sangtec 100 assays during cardiac surgery: Part III--Dose haemolysis affect their accuracy?

Neurone-specific enolase (NSE) and Sangtec 100 (S-100) are useful for detecting cerebral damage during cardiopulmonary bypass (CPB). However, red cells contain NSE, and the haemolysis frequently caused by CPB could produce a false rise in NSE; S-100 is not found in red cells and should not be affected. We, therefore, compared the effects of haemolysis on NSE and S-100 to see if correction was necessary and possible. From seven patients, serial dilutions of haemolysed red cells were added to plasma (1/64-1/2048), measured for absorption at 540 nm and assayed for NSE and S-100. S-100 concentrations showed no change with haemolysis. Measured NSE increased significantly with haemolysis > 1/512 (an increase of 6.6 micrograms/ml): a correction formula is presented. In 39/48 patients after CPB, mean haemolysis was < 1/256 and would not need any correction. NSE and S-100 assay can, therefore, be used throughout CPB, which allows both glial and neuronal damage to be studied.

Artifacts↗

Heterogeneous expression of sulphotransferases in periportal and perivenous hepatocytes prepared from male and female rat liver.

Sulphotransferase (ST) is a family of enzymes responsible for metabolism and detoxication of endobiotics and xenobiotics. We investigated the hepatic acinar distribution of three sulphotransferases: phenol sulphotransferase (PST), oestrogen sulphotransferase (EST), and hydroxysteroid sulphotransferase (HST) in male and female rat livers by measurement of enzyme activities in isolated periportal and perivenous hepatocytes. The distribution was confirmed by immunohistochemistry. EST activity was located predominantly in the perivenous hepatocytes in male rats but not in female rats, where residual activity is catalysed by another ST. HST activity was not significantly different in periportal and perivenous hepatocytes in either male or female rats. For PST, a more widespread distribution was observed, with slight predominance in the periportal regions. The results indicate heterogeneous distribution of ST isoenzymes in the periportal and perivenous hepatocytes isolated from male and female rat livers.

Animals↗

Egg-sharing in assisted conception: ethical and practical considerations.

The present acute shortage of eggs for donation cannot be overcome unless adequate guidelines are set to alleviate the anxieties regarding payments, in cash or kind, to donors. The current Human Fertilisation and Embryology Authority (HFEA) guidelines do not allow direct payment to donors but accept the provision of lower cost or free in vitro fertilization (IVF) treatment to women in recognition of oocyte donation to anonymous recipients. Egg-sharing achieved in this way enables two infertile couples to benefit from a single surgical procedure. However, the practical guidelines related to this approach are ill-defined at the present time leading to some justifiable uncertainty. A pilot study was therefore undertaken in order to establish the place of egg-sharing in an assisted conception programme. The current HFEA guidelines on medical screening of patients, counselling, age and rigid anonymity between the donor and recipient were followed. The study involved 55 women (25 donors and 30 recipients) in 73 treatment cycles involving fresh and frozen-thawed embryos. Donors were previous IVF patients who, regardless of their ability to pay, shared their eggs equally with matched anonymous recipients. They paid only for their consultations and tests right up to the point of being matched with a recipient. The sole recipient paid the cost applicable in egg donation of a single egg collection, although both received embryo transfers. The results indicate that although the recipients were older than the donors (41.4 +/- 0.9 versus 31.6 +/- 0.5 years), and there was no difference in the mean number of eggs allocated, the percentage fertilization rates, or the mean number of embryos transferred, there were more births per patient amongst recipients than amongst donors (30 versus 20%). We conclude that providing the donors are selected carefully, this scheme whereby a sub-fertile donor helps a sub-fertile recipient is a very constructive way of solving the problem of the shortage of eggs for donation. There are also the advantages of including a group of women who would otherwise be denied treatment. Problems related to 'patient coercion' can, in our view, be fully overcome by the application of strict common-sense safeguards. The ideal of pure altruism is not without its medical and moral risk. The success of egg-sharing depends on shared interests and a degree of altruism between the donor, the recipient and the centre. The current HFEA guidelines should be applauded for enabling a highly effective concept of mutual help to develop.

Adult↗

Optimal lead selection for detection of ST segment shifts.

A comparison was made to determine the ability of optimal sets of 2-6 unipolar leads and a normal Holter lead set to estimate ST potential distributions changes induced by balloon inflation during angioplasty. The performance of these lead sets was compared to measurements observed in recorded 32-lead body surface maps. Unipolar lead potentials were estimated using a linear, least mean squared error estimator of the total body surface map. The correlation between maximum ST potential change in the body surface map and that predicted by the unipolar lead sets ranged from 0.84-0.93. The correlation between maximum ST segment change measured from the body surface map and measured from the Holter leads was 0.29. Therefore, shifts in ST segment potentials can accurately be estimated from a small number of unipolar leads. In contrast, current bipolar ambulatory recording techniques may introduce significant bias to such estimates.

Angioplasty, Balloon, Coronary↗

Design, production and characterization of antibodies discriminating between the phenol- and monoamine-sulphating forms of human phenol sulphotransferase.

1. Phenol sulphotransferases (PSTs) are important enzymes in xenobiotic and endobiotic detoxication, and a key component of the body's chemical defence mechanism. 2. Human phenol-(P-PST) and monoamine-(M-PST) sulphating forms of PST share 93% amino acid sequence identity, and to date the various antibodies produced against PSTs all recognize both enzymes. 3. We have identified two peptides based on the cDNA-derived amino acid sequences of human P-PST and M-PST, which elicited for the first time antibodies capable of discriminating between these highly homologous enzymes. 4. These antibodies represent valuable tools for studying the expression, distribution and function of human phenol sulphotransferases.

Amino Acid Sequence↗

Preparation and characterization of anti-peptide antibodies directed against human phenol and hydroxysteroid sulphotransferases.

Sulphotransferases (STs) catalyze the sulphation and, in general, detoxication of a large number of xenobiotics and endogenous compounds. A total of six synthetic peptides derived from the cDNA-derived amino acid sequences of the human phenol-sulphating form of phenosulphotransferase (P-PST) and human hydroxysteroid sulphotransferase (HST)--three from each sequence--were separately conjugated to the carrier protein keyhole limpet hemocyanin, and used to immunize rabbits. One successful antibody preparation was produced from among the P-PST peptides, and two from the HST peptides. On immunoblot analysis following SDS/PAGE, the anti-P-PST antibodies recognized two major forms of phenol ST in man, P-PST and the monoamine-sulphating form of PST, M-PST, and the two antibody preparations against HST recognized the human HST. These experiments demonstrate that it is possible to design specific antibodies against human sulphotransferases based on their amino acid sequences.

Adjuvants, Immunologic↗

Sulfation of endogenous compounds and xenobiotics--interactions and function in health and disease.

Sulfation is a major detoxication mechanism for endogenous compounds and xenobiotics performed by a family of sulfotransferase isoenzymes. Understanding the normal cellular functions of these different sulfotransferases and the way in which endogenous and exogenous factors are able to influence their activity and expression will provide us with the information necessary to develop novel therapeutic strategies for conditions where sulfation may be implicated. This concept is discussed and is illustrated by examples including adverse drug reactions, fetal development and cancer.

Amino Acid Sequence↗

Immunohistochemical localisation of hydroxysteroid sulphotransferase in human breast carcinoma tissue: a preliminary study.

Understanding the function and regulation of the metabolism of steroid hormones by breast tumours will be instrumental to the development of novel treatments for this widespread disease. We have examined the expression of hydroxysteroid sulphotransferase, an enzyme which inactivates many steroids, in particular androgens, in normal breast tissue and in six ductal-type mammary carcinomas using immunohistochemistry. The enzyme is not expressed in the epithelial cells which line the normal breast duct, but is present in significant amounts in neoplastic cells, suggesting that the gene encoding this protein is activated at some stage of the neoplastic transformation. The implications of this finding for the role of steroid metabolism in breast cancer are discussed.

Breast↗

Mobilisation of Ph-negative peripheral blood stem cells in CML with idarubicin and cytarabine.

Recent interest in autologous transplantation in chronic myeloid leukaemia (CML) has focused on attempts to select out putatively normal Ph-negative progenitor cells for subsequent reinfusion after high dose therapy. One way in which this may be achieved is by collecting peripheral blood stem cells (PBSCs) during the early regenerative phase following chemotherapy when Ph-negative cells seem to have a short term proliferative advantage. Data now suggest that it is possible to collect Ph-negative (and occasionally PCR negative) progenitor cells in a significant number of CML patients, a proportion of whom will go on to achieve a cytogenetic remission post-autografting. The durability of these remissions and the effect on long term survival remain to be established and at present this form of therapy should be reserved for those unsuitable for allogeneic transplantation who have failed to achieve a major cytogenetic response to interferon-alpha.

Cell Separation↗

Immunochemical characterisation of a dehydroepiandrosterone sulfotransferase in rats and humans.

A member of the rat liver hydroxysteroid sulfotransferase (ST) enzyme family metabolising dehydroepiandrosterone (DHEA) was purified from female rats and used to raise rabbit polyclonal antibodies. Characterisation of this antibody preparation demonstrated that it was specific for DHEA ST, and recognised a single 30-kDa protein on immunoblot analysis of rat liver cytosol which was expressed preferentially in female rat liver, and immunohistochemical localisation of the protein in female rat liver determined that DHEA ST was distributed homogeneously in the cytoplasm of hepatocytes. Examination of the extrahepatic expression of this protein showed it to be located predominantly in the liver, although a small amount of enzyme activity was found in the kidney which was not apparently subject to the same sex difference as the hepatic activity. Immunological analysis suggested that this activity was not due to the action of DHEA ST, but to another, unidentified ST isozyme. The antibody cross-reacted strongly with adult human liver DHEA ST, recognising a protein of 35 kDa on immunoblotting. Using this antibody preparation, the distribution of DHEA ST in mid-trimester human fetal tissues was examined, and it was shown that the enzyme is expressed in the adrenal and liver, but not to any significant extent in the kidney or lung. This antibody therefore provides a powerful tool for investigating the function of DHEA ST.

Adrenal Glands↗

Inhibition of human and rabbit liver steroid and xenobiotic UDP-glucuronosyltransferases by tertiary amine drugs--implications for adverse drug reactions.

1. To investigate the hypothesis that disruption of glucuronidation of endogenous compounds by drugs represents a potential mechanism for pathogenesis of adverse drug reactions, the effects of a range of tertiary amine and amide drugs (many with effects on sex hormone function) on steroid hormone and xenobiotic UDP-glucuronosyltransferase activities in human and rabbit liver microsomes were studied in vitro. 2. Chlorpromazine, amitriptyline, imipramine, promethazine and cyproheptadine were consistently the most potent inhibitors of the glucuronidation of testosterone, androsterone, oestriol and 1-naphthol, the steroid activities being more susceptible to inhibition (up to 90%). 3. Carbamazepine, diphenhydramine, sulphadimethoxine, dimenhydrinate and (+/-)-chlorpheniramine had little effect on the UDPGT activities measured. 4. The structural features within this group of compounds required for inhibitory potency were the presence of a rigid tricyclic ring (e.g. phenothiazine) and either a dimethylaminopropyl or a methylpiperidine side-chain. 5. The implications of these data for involvement of disruption of the normal cellular function of glucuronidation in the pathogenesis of frequently observed adverse side-effects associated with these compounds are discussed.

Amines↗

Glucuronidation of imipramine in rabbit and human liver microsomes: assay conditions and interaction with other tertiary amine drugs.

The present work confirms that rabbit liver microsomes afford a good in vitro model for studying the glucuronidation of drugs containing tertiary amino groups. Furthermore, the availability of the assay procedure described above will allow us to understand further the basis for the inter-species differences in the metabolism of tertiary amines, and will eventually aid in our identification of the UDPGT isozyme(s) responsible for the conjugation of these compounds in man.

Amines↗

Histologic comparison of regeneration in human intrabony defects when osteogenin is combined with demineralized freeze-dried bone allograft and with purified bovine collagen.

A bone-inductive protein, osteogenin, has been isolated from long bones of humans and offers promise as a grafting material. Studies, however, suggest that osteogenin must be combined with a bone-derived matrix in order to initiate bone differentiation. The purpose of this study was to determine if osteogenin combined with demineralized freeze dried bone allograft (DFDBA), a bone-derived matrix, and with a bovine tendon-derived matrix will enhanced regeneration of intrabony defects in humans. The tendon-derived matrix and DFDBA used alone served as controls. The ability of each material to form a new attachment apparatus was evaluated independently in submerged and nonsubmerged environments in 2 patient populations. Lymphocyte testing was performed to assess development of an immune reaction to osteogenin. The most apical level of calculus on the root served as the histologic reference point to measure regeneration. Biopsies were obtained at 6 months and regeneration was measured histomorphometrically by 2 blinded evaluators. Serial sections from 36 submerged defects in 8 patients and 50 nonsubmerged defects in 6 patients were submitted for statistical analysis. Mean results indicate that osteogenin combined with DFDBA significantly enhanced regeneration of a new attachment apparatus and component tissues in a submerged environment. DFDBA plus osteogenin and DFDBA alone formed significantly more new attachment apparatus and component tissues than either the tendon-derived matrix plus osteogenin or the tendon-derived matrix alone in both submerged and nonsubmerged environments. There were no significant differences between the tendon-derived matrix plus osteogenin and the tendon-derived matrix alone in either the submerged or nonsubmerged environment. Osteogenin does not impair normal lymphocyte blastogenesis at 6 months postsurgical challenge.

Alveolar Bone Loss↗

Purification and immunochemical characterization of a rat liver sulphotransferase conjugating paracetamol.

Paracetamol sulphotransferase (ST) was purified 250-fold from male rat liver, and the pure enzyme used to elicit antibodies in rabbit. The enzyme was active towards paracetamol at pH 9.0, as well as towards several commonly used drugs, and formed sulphates at both O- and N-atoms. Comparison of the substrate specificity of paracetamol ST with that of aryl sulphotransferases isolated by other workers suggested that we have purified a previously unknown isoenzyme of rat liver ST, although the difficulties of characterization of STs based on their substrate specificities is noted. The antibody preparation recognized only one polypeptide (Mr = 35,000) on immunoblot analysis of rabbit liver cytosol, corresponding to purified paracetamol ST. Analysis of the tissue distribution of this protein demonstrated that its expression was restricted to the liver, as was the enzyme activity. The observed sex difference in paracetamol ST (males greater than females) was determined by immunoblot analysis to be the result of reduced enzyme protein levels in females. In human liver cytosol, the antibody recognized two polypeptides, probably corresponding to M- and P-phenol STs, suggesting significant sequence similarity between rat and human phenol sulphotransferases.

Acetaminophen↗

The 5'-flanking sequences of Drosophila melanogaster tRNA5Asn genes differentially arrest RNA polymerase III.

Three tRNA5Asn genes have been subcloned from a tRNA gene cluster isolated from the cytogenetic locus 42A of Drosophila melanogaster. The three tRNAAsn genes, contained on plasmids pAsn6, pAsn7, and pAsn8, have identical mature tRNA coding regions but have different 5'- and 3'-flanking sequences. In vitro transcription in Drosophila Schneider S3 cell-free extracts showed the tRNAAsn genes had different transcription efficiencies. pAsn8 had a transcription efficiency of approximately 8 transcripts/gene/h, whereas pAsn6 was a less active template at 5 transcripts/gene/h. pAsn7 was the poorest template at 1.5 transcripts/gene/h. Exchanging 5'-flanking regions of the tRNAAsn genes showed that the differences in transcription efficiencies were attributable to the corresponding 5'-flanking region. Transcription of each of the tRNAAsn genes revealed a different optimum for KC1 concentration for each template which also was directly attributable to the corresponding 5'-flanking region. The "salt effect" is not related to the ability of the three tRNAAsn genes to sequester transcription factors as determined using the stable complex competition assay. Rather, this effect appears to be due to the ability of the respective 5'-flanking regions to interact with RNA polymerase III. The poorest transcription template, pAsn7, was a better competitor in the stable complex formation assay than either pAsn8 or pAsn6. We conclude that the pAsn7 stable complex binds and functionally arrests RNA polymerase III in the initiation reaction.

Animals↗