PubMed Health⌕ Search

Biomedical subjects

S Sharp

Publications and source records attributed to S Sharp.

At least 19 recordsLinked to original sources
PubMed2002

Sequence of Plasmodium falciparum chromosomes 1, 3-9 and 13.

Since the sequencing of the first two chromosomes of the malaria parasite, Plasmodium falciparum, there has been a concerted effort to sequence and assemble the entire genome of this organism. Here we report the sequence of chromosomes 1, 3-9 and 13 of P. falciparum clone 3D7--these chromosomes account for approximately 55% of the total genome. We describe the methods used to map, sequence and annotate these chromosomes. By comparing our assemblies with the optical map, we indicate the completeness of the resulting sequence. During annotation, we assign Gene Ontology terms to the predicted gene products, and observe clustering of some malaria-specific terms to specific chromosomes. We identify a highly conserved sequence element found in the intergenic region of internal var genes that is not associated with their telomeric counterparts.

Animals↗
PubMed2002

Complete genome sequence of the model actinomycete Streptomyces coelicolor A3(2).

Streptomyces coelicolor is a representative of the group of soil-dwelling, filamentous bacteria responsible for producing most natural antibiotics used in human and veterinary medicine. Here we report the 8,667,507 base pair linear chromosome of this organism, containing the largest number of genes so far discovered in a bacterium. The 7,825 predicted genes include more than 20 clusters coding for known or predicted secondary metabolites. The genome contains an unprecedented proportion of regulatory genes, predominantly those likely to be involved in responses to external stimuli and stresses, and many duplicated gene sets that may represent 'tissue-specific' isoforms operating in different phases of colonial development, a unique situation for a bacterium. An ancient synteny was revealed between the central 'core' of the chromosome and the whole chromosome of pathogens Mycobacterium tuberculosis and Corynebacterium diphtheriae. The genome sequence will greatly increase our understanding of microbial life in the soil as well as aiding the generation of new drug candidates by genetic engineering.

Bacterial Proteins↗
PubMed2002

The genome sequence of Schizosaccharomyces pombe.

We have sequenced and annotated the genome of fission yeast (Schizosaccharomyces pombe), which contains the smallest number of protein-coding genes yet recorded for a eukaryote: 4,824. The centromeres are between 35 and 110 kilobases (kb) and contain related repeats including a highly conserved 1.8-kb element. Regions upstream of genes are longer than in budding yeast (Saccharomyces cerevisiae), possibly reflecting more-extended control regions. Some 43% of the genes contain introns, of which there are 4,730. Fifty genes have significant similarity with human disease genes; half of these are cancer related. We identify highly conserved genes important for eukaryotic cell organization including those required for the cytoskeleton, compartmentation, cell-cycle control, proteolysis, protein phosphorylation and RNA splicing. These genes may have originated with the appearance of eukaryotic life. Few similarly conserved genes that are important for multicellular organization were identified, suggesting that the transition from prokaryotes to eukaryotes required more new genes than did the transition from unicellular to multicellular organization.

Base Sequence↗
PubMed2001

Influence of culture system and medium enrichment on sulfotransferase and sulfatase expression in male rat hepatocyte cultures.

The expression of sulfotransferase and steroid sulfatase was studied in rat liver using the most promising culture models of hepatocytes, including monolayer culture with a pyruvate (30 mM) enriched medium, co-culture with rat epithelial cells from primitive biliary origin and collagengel sandwich culture. In the latter, addition of dexamethasone (1 microM) to the medium was examined. Phenol sulfotransferase enzymes (SULT1) were studied by measuring activities towards 4-methylphenol and estradiol, hydroxysteroid sulfotransferase (SULT2A) activity was determined towards dehydroepiandrosterone (DHEA). Microsomal steroid sulfatase activity was measured towards estrone sulfate. Western blot analysis was carried out using polyclonal antibodies raised against rat phenol sulfotransferase SULT1A1 (ASTIV), estrogen sulfotransferase SULT1E1 (EST) and hydroxysteroid sulfotransferase (HST). SULT2A activity towards DHEA was maintained at a high level during the whole culture time. In the co-culture it even reached the level of freshly isolated cells. Addition of pyruvate had no positive effect on the activity measured in monolayer cultures. High SULT1A1 activity towards 4-methylphenol was found in the co-culture system. In the monolayer culture, the activity initially decreased with 35% but was then kept at a constant level, while in the sandwich culture low activities were measured. For dexamethasone, an inducing effect on the various SULT activities could not be detected. Independently of the culture model used, the SULT1E1 activity towards estradiol decreased to 20% and 5% of the initial activity after four and seven days of culture, respectively. Microsomal steroid sulfatase activity was best maintained in collagengel sandwich cultures. During the first four days in culture it retained 73% of the initial activity, afterwards it decreased to 40% of the activity found in freshly isolated hepatocytes, irrespective of the culture conditions. High expectations exist for collagengel sandwich cultures, however, in our study the results were rather disappointing. Monolayer is a suitable culture model for short-term purposes. For long-term in vitro biotransformation studies, co-culture is preferred but is rather complex.

Albumins↗
PubMed2000

The BCSH guideline on addressograph labels: experience at a cardiothoracic unit and findings of a telephone survey.

In 1998 we implemented a BCSH recommendation that addressograph labels should not be used on blood transfusion specimen tubes. Over a 12-month period before the ban was introduced our laboratory received 5964 red cell transfusion requests, 182 (3.1%) of which contained an error in the identification details (ID) supplied on the request form and/or specimen. Three of these errors were of the 'wrong patient' type, i.e. the sample belonged to a different patient from the one whose ID appeared on the specimen tube and request form. Over the 12 months after the ban was introduced 511 (8. 1%) of 6326 requests contained a labelling error, an increase in error rate of 165%; no wrong-patient errors were identified, however. In a survey, seven (29.2%) of 24 transfusion laboratories in the UK accepted specimens labelled with addressograph stickers; in four of these cases a local blood transfusion committee had agreed that the BCSH guideline should not be followed. We believe the BCSH guideline is valid; its implementation, however, has major financial and workload implications, which probably explains why many hospitals apparently do not comply with it.

Blood Banks↗
PubMed1999

Estradiol formation by human osteoblasts via multiple pathways: relation with osteoblast function.

The importance of estrogens in bone metabolism is illustrated by the accelerated bone loss and increase in osteoporotic fractures associated with postmenopausal estrogen deficiency. In this study, the expression and activity of the enzymes involved in estrogen metabolism in human osteoblastic cells were investigated in relation to differentiation of these cells. PCR reactions using mRNA from an in vitro differentiating human cell line (SV-HFO) were performed to assess mRNA expression of the enzymes aromatase, different subtypes of 17beta-hydroxysteroid dehydrogenase (17beta-HSD), and steroid sulfatase. Aromatase, sulfatase, and 17beta-HSD type 2 and 4 were found to be expressed throughout differentiation. Expression of 17beta-HSD type 3, however, was relatively weak, except for early time points in differentiation. Type 1 17beta-HSD expression was not detected. Aromatase activity decreased during differentiation, as was demonstrated by the conversion of androstenedione (A) and testosterone (T) into estrone (E(1)) and estradiol (E(2)), respectively. The 17beta-HSD isozymes catalysing a reductive reaction convert androstenedione and estrone into testosterone and estradiol, respectively. Their activity declined with differentiation. Analysis of 17beta-HSD activity indicated both oxidative (E(2) to E(1); T to A) and reductive (E(1) to E(2); A to T) metabolism at all stages of osteoblast differentiation. Both activities declined as cells moved toward a differentiating mineralizing phenotype. However, the oxidative reaction was increasingly in favor of the reductive reaction at all times during differentiation. Sulfatase activity, as demonstrated by the conversion of estrone-sulfate into estrone, was constant during differentiation. In conclusion, we have demonstrated that all enzymes necessary for estrogen metabolism are expressed and biologically active in differentiating human osteoblasts. The activity of aromatase and 17beta-HSD was found to be dependent on the stage of cell differentiation. In addition, human osteoblasts effectively convert estradiol into estrone. The efficacy of osteoblasts to synthesize estradiol may determine the ultimate change in rate of bone turnover after menopause, as well as the development of osteoporosis. Moreover, the enzymes involved in the metabolism of estradiol may form a target for intervention.

17-Hydroxysteroid Dehydrogenases↗
PubMed1999

Contrast agent neurotoxicity presenting as subarachnoid hemorrhage.

A patient developed signs, symptoms, and radiologic findings compatible with acute subarachnoid hemorrhage after receiving a large dose of heparin and intravascular contrast medium for coronary angiography and stent placement. Subsequent CT indicated the subarachnoid enhancement was due to contrast. Neurotoxicity from contrast agents is well-known, however this is an unusual report of toxicity mimicking subarachnoid hemorrhage clinically and radiologically.

Aged↗
PubMed1999

Randomised controlled trial of follow up care in general practice of patients with myocardial infarction and angina: final results of the Southampton heart integrated care project (SHIP). The SHIP Collaborative Group.

OBJECTIVE: To assess the effectiveness of a programme to coordinate and support follow up care in general practice after a hospital diagnosis of myocardial infarction or angina. DESIGN: Randomised controlled trial; stratified random allocation of practices to intervention and control groups. SETTING: All 67 practices in Southampton and south west Hampshire, England. SUBJECTS: 597 adult patients (422 with myocardial infarction and 175 with a new diagnosis of angina) who were recruited during hospital admission or attendance at a chest pain clinic between April 1995 and September 1996. INTERVENTION: Programme to coordinate preventive care led by specialist liaison nurses which sought to improve communication between hospital and general practice and to encourage general practice nurses to provide structured follow up. MAIN OUTCOME MEASURES: Serum total cholesterol concentration, blood pressure, distance walked in 6 minutes, confirmed smoking cessation, and body mass index measured at 1 year follow up. RESULTS: Of 559 surviving patients at 1 year, 502 (90%) were followed up. There was no significant difference between the intervention and control groups in smoking (cotinine validated quit rate 19% v 20%), lipid concentrations (serum total cholesterol 5.80 v 5.93 mmol/l), blood pressure (diastolic pressure 84 v 85 mm Hg), or fitness (distance walked in 6 minutes 443 v 433 m). Body mass index was slightly lower in the intervention group (27.4 v 28.2; P=0.08). CONCLUSIONS: Although the programme was effective in promoting follow up in general practice, it did not improve health outcome. Simply coordinating and supporting existing NHS care is insufficient. Ischaemic heart disease is a chronic condition which requires the same systematic approach to secondary prevention applied in other chronic conditions such as diabetes mellitus.

Angina Pectoris↗
PubMed1999

Kinetic properties of human dopamine sulfotransferase (SULT1A3) expressed in prokaryotic and eukaryotic systems: comparison with the recombinant enzyme purified from Escherichia coli.

Sulfation, catalyzed by members of the sulfotransferase enzyme family, is a major metabolic pathway which modulates the biological activity of numerous endogenous and xenobiotic chemicals. A number of these enzymes have been expressed in prokaryotic and eukaryotic systems to produce protein for biochemical and physical characterization. However, the effective use of heterologous expression systems to produce recombinant enzymes for such purposes depends upon the expressed protein faithfully representing the "native" protein. For human sulfotransferases, little attention has been paid to this despite the widespread use of recombinant enzymes. Here we have validated a number of heterologous expression systems for producing the human dopamine-metabolizing sulfotransferase SULT1A3, including Escherichia coli, Saccharomyces cerevisiae, COS-7, and V79 cells, by comparison of Km values of the recombinant enzyme in cell extracts with enzyme present in human platelets and with recombinant enzyme purified to homogeneity following E. coli expression. This is the first report of heterologous expression of a cytosolic sulfotransferase in yeast. Expression of SULT1A3 was achieved in all cell types, and the Km for dopamine under the conditions applied was approximately 1 microM in all heterologous systems studied, which compared favorably with the value determined with human platelets. We also determined the subunit and native molecular weights of the purified recombinant enzyme by SDS-PAGE, electrospray ionization mass spectrometry, dynamic light scattering, and sedimentation analysis. The enzyme purified following expression in E. coli existed as a homodimer with Mr approximately 68,000 as determined by light scattering and sedimentation analysis. Mass spectrometry revealed two species with experimentally determined masses of 34,272 and 34,348 which correspond to the native protein with either one or two 2-mercaptoethanol adducts. We conclude that the enzyme expressed in prokaryotic and eukaryotic heterologous systems, and also purified from E. coli, equates to that which is found in human tissue preparations.

Amino Acid Sequence↗
PubMed1998

Biology and function of the reversible sulfation pathway catalysed by human sulfotransferases and sulfatases.

Sulfation and sulfate conjugate hydrolysis play an important role in metabolism, and are catalysed by members of the sulfotransferase and sulfatase enzyme super-families. In general, sulfation is a deactivating, detoxication pathway, but for some chemicals the sulfate conjugates are much more reactive than the parent compound. The range of compounds which are sulfated is enormous, yet we still understand relatively little of the function of this pathway. This review summarises current knowledge of the sulfation system and the enzymes involved, and illustrates how heterologous expression of sulfotransferases (SULTs) and sulfatases is aiding our appreciation of the properties of these important proteins. The role of sulfation in the bioactivation of procarcinogens and promutagens is discussed, and new data on the inhibition of the sulfotransferase(s) involved by common dietary components such as tea and coffee are presented. The genetic and environmental factors which are known to influence the activity and expression of human SULTs and sulfatases are also reviewed.

Amino Acid Sequence↗
PubMed1998

Microsomal steroid sulfatase: interactions with cytosolic steroid sulfotransferases.

Net sulfation of 4-methylumbelliferone in intact hepatocytes is regulated, in part, by substrate cycling between sulfotransferases (SULT) and arylsulfatases (ARS). Thus, ARS have the potential to influence rates of net sulfate conjugation of a variety of compounds in intact cells via interaction with SULT. Unlike ARSA and ARSB, which are lysosomal, steroid sulfate sulfatase (ARSC, also known as STS) is localized exclusively in the endoplasmic reticulum (ER). The present study was designed to assess the existence and extent of substrate cycling between steroids and their sulfate conjugates through ARSC and SULT, and also to initiate studies of the topology of the catalytic site of ARSC in the rat liver ER. Addition of rat liver microsomes to cytosol and 3'-phosphoadenosine 5'-phosphosulfate (PAPS) reduced rates of sulfation of dehydroepiandrosterone (DHEA) by SULT, and similarly hydrolysis of DHEA sulfate (DHEAS) was reduced when recombinant human hydroxysteroid SULT was added to rat liver microsomes in the presence of PAPS. There was no evidence for ARSC latency in the presence of detergent at either 4 or 37 degrees C, indicating that facilitated transport of steroid sulfates across the ER membrane may not be required for ARSC activity. The effect of proteases on ARSC activity in intact and disrupted microsomes was determined and compared with effects on components of the glucose-6-phosphatase system known to be localized on the lumenal and cytoplasmic surfaces of the ER. In contrast to the components of the glucose-6-phosphatase system, activity of ARSC in both intact and disrupted microsomes was substantially more resistant to protease inactivation. Our results indicate that substrate cycling of steroids and their sulfates does occur, and suggest that the active site of ARSC may be located within the ER membrane.

Animals↗
PubMed1998

Cartilage protective agent (CPA) Ro 32-3555, a new matrix metalloproteinase inhibitor for the treatment of rheumatoid arthritis.

CPA was well tolerated at all dose levels (10-150 mg) following single oral dose administration to healthy male volunteers. There was no relationship between the intensity, duration and number of adverse events reported and the dose of CPA. There was a dose-related increase in exposure as measured by AUC0-infinity and Cmax. Administration of 10 mg CPA following food resulted in a delayed tmax, and a significant decrease in Cmax but not AUC0-infinity.

Adult↗
PubMed1998

Follow-up care in general practice of patients with myocardial infarction or angina pectoris: initial results of the SHIP trial. Southampton Heart Integrated Care Project.

OBJECTIVE: We aimed to assess the effectiveness of a nurse-led programme to ensure that follow-up care is provided in general practice after hospital diagnosis of myocardial infarction (MI) or angina pectoris. METHODS: We conducted a randomized controlled trial with stratified random allocation of practices to intervention and control groups within all 67 practices in Southampton and South-West Hampshire, England. The subjects were 422 adult patients with a MI and 175 patients with a new diagnosis of angina recruited during hospital admission or chest pain clinic attendance between April 1995 and September 1996. Intervention involved a programme of secondary preventive care led by specialist liaison nurses in which we sought to improve communication between hospital and general practice and to encourage general practice nurses to provide structured follow-up. The main outcome measures were: extent of general practice follow-up; attendance for cardiac rehabilitation; medication prescribed at hospital discharge; self-reported smoking, diet and exercise; and symptoms of chest pain and shortness of breath. Follow-ups of 90.1 % of subjects at 1 month and 80.6% at 4 months were carried out. RESULTS: Median attendance for nurse follow-up in the 4 months following diagnosis was 3 (IQR 2-5) in intervention practices and 0 (IQR 0-1) in control practices; the median number of visits to a doctor was the same in both groups. At hospital discharge, levels of prescribing of preventive medication were low in both intervention and control groups: aspirin 77 versus 74% (P = 0.32), cholesterol lowering agents 9 versus 10% (P = 0.8). Conversely, 1 month after diagnosis, the vast majority of patients in both groups reported healthy lifestyles: 90 versus 84% reported eating healthy food (P = 0.53); 73 versus 67% taking regular exercise (P = 0.13); 89 versus 92% not smoking (P = 0.77). Take up of cardiac rehabilitation was 37% in the intervention group and 22% in the control group (P = 0.001); the median number of sessions attended was also higher (5 versus 3 out of 6). CONCLUSIONS: The intervention of a liaison nurse is effective in ensuring that general practice nurses follow-up patients after hospital discharge. It does not alter the number of follow-up visits made by the patient to the doctor. Levels of prescribing and reported changes in behaviour at hospital discharge indicate that the main tasks facing practice nurses during follow-up are to help patients to sustain changes in behaviour, to encourage doctors to prescribe appropriate medication and to encourage patients to adhere to medication while returning to an active life. These are very different tasks to those traditionally undertaken by practice nurses in relation to primary prevention, where the emphasis has been on identifying risk and motivating change. Assessment of the effectiveness of practice nurses in undertaking these new tasks requires a longer follow-up.

Adult↗
PubMed1997

3-D histo-radiographic comparison of surgical clearances of microcalcified lesions in breast localization biopsies.

There is controversy as to the value of the radiological or pathological estimation of surgical clearance of microcalcifying breast lesions. An important part of this issue has been addressed by coordinated three-dimensional radiographic and histological examination of a prospective consecutive series of 40 benign and malignant mammographically detected lesions in surgical breast biopsy specimens containing microcalcifications, including 20 cases of ductal carcinoma in situ. They were radiographed from four viewpoints by means of rotation in a radiolucent tetrahedral container. The planes of histological examination were then chosen to correspond to the radiographic view showing the minimum separation of the edge of the specimen and the outermost microcalcification. There was a close correlation (Spearman ranked) between the least tetrahedral radiographic distance and the corresponding histological distance separating the surgical margin of excision. There were, however, incompatible Wilcoxon signed ranking orders when comparing the least tetrahedral distance or the histological distance with all four single radiographic views, including the conventional specimen radiographic view. Two-dimensional specimen mammography and standardized histological examination are suboptimal and may thus have contributed to confusion as to the value of determining adequate surgical excision of ductal carcinoma in situ of the breast. Although labour-intensive, use of four-view radiography and choice of the appropriate plane of histological examination give a better correlation of the radiographic estimates of surgical clearance with histology than single-view specimen radiography and arbitrary histological sectioning.

Biopsy↗
PubMed1997

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↗