Complete next-to-leading order QCD corrections to the photon structure functions F2 gamma (x,Q2) and FL gamma (x,Q2).
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Journal Article↗
Biomedical subjects
J Smith
Publications and source records attributed to J Smith.
Non-invasive detection of malignancy by identification of unusual CD44 gene activity in exfoliated cancer cells.
OBJECTIVE: To investigate non-invasive detection of cancer by testing for unusual CD44 gene activity in a clinical sample as an indicator of exfoliated tumour cells. DESIGN: Case-control study. SUBJECTS: 44 unselected, consecutive patients with bladder cancer and 46 people with no evidence of neoplasia. MAIN OUTCOME MEASURE: Presence or absence of large CD44 gene products containing exon 6 derivatives in urine samples. RESULTS: Novel abnormalities in the pattern of expression of this gene, seen specifically in tumour tissue, led to cloning of a newly recognised coding region in it (exon 6). This was tested as a probe for detection of exfoliated malignant cells in naturally voided urine. CD44 gene products extracted from the urine and amplified with polymerase chain reaction contained predicted electrophoretic band of 735 base pairs in 40 of the 44 patients with bladder cancer (sensitivity 91%). Products from 38 of the 46 people with no evidence of neoplasia showed no such band (specificity 83%). CONCLUSIONS: Unusual activity of the CD44 locus in neoplasia and malignancy is confirmed, and techniques for the analysis of such activity can enable non-invasive investigation of patients for primary or recurrent bladder cancer or for other tumours that shed neoplastic cells into body fluids.
Adult↗
Folate-deficiency-induced homocysteinaemia in rats: disruption of S-adenosylmethionine's co-ordinate regulation of homocysteine metabolism.
In a recent hypothesis [Selhub and Miller (1992) Am. J. Clin. Nutr. 55, 131-138], we proposed that homocysteinaemia arises from an interruption in S-adenosylmethionine's (AdoMet) coordinate regulation of homocysteine metabolism. The present study was undertaken to test a prediction of this hypothesis, that homocysteinaemia due to folate deficiency results from impaired homocysteine remethylation due to the deficiency and impaired synthesis of AdoMet, with the consequent inability of this metabolite to function as an activator of homocysteine catabolism through cystathionine synthesis. Rats were made folate-deficient by feeding them with a folate-free amino-acid-defined diet supplemented with succinylsulphathiazole. After 4 weeks, the deficient rats exhibited a 9.8-fold higher mean plasma homocysteine concentration and a 3.2-fold lower mean hepatic AdoMet concentration compared with folate-replete controls. Subsequent supplementation for 3 weeks of the folate-deficient rats with increasing levels of folate in the diet resulted in graded decreases in plasma homocysteine levels, accompanied by graded increases in hepatic AdoMet levels. Thus plasma homocysteine and hepatic AdoMet concentrations were inversely correlated as folate status was modified. In a second experiment, the elevation of plasma homocysteine in the deficient rats was found to be reversible within 3 days by intraperitoneal injections of ethionine. This effect of ethionine is thought to be exerted through S-adenosylethionine, which is formed in the liver of these rats. Like AdoMet, S-adenosylethionine is an activator of cystathionine beta-synthase and will effectively promote the catabolism of homocysteine through cystathionine synthesis. In crude liver homogenates of the rats treated with ethionine, cystathionine beta-synthase activity was 3-fold higher than that measured in homogenates from vehicle-treated controls.
Animals↗
ICAM-1 expression on human brain microvascular endothelial cells.
There is evidence that leukocytes play an important role in mediating tissue injury during acute ischemic stroke. Endothelial cell adhesive molecules such as ICAM-1 are required for the migration of leukocytes into the brain. Using an Elisa, we compared the expression of ICAM-1 by human brain microvascular endothelial cells with human umbilical vein endothelial cells. There was constitutive surface expression of ICAM-1 on both brain and umbilical vein endothelial cells. With cytokine (IL-1 beta or TNF) or lipopolysaccaride stimulation, ICAM-1 surface expression increased to a greater extent on brain than on umbilical vein endothelial cells. Dexamethasone at doses up to 100 microM had no effect on inhibiting cytokine-mediated upregulation of ICAM-1 on human brain microvascular endothelial cells.
Antigens, CD↗
The Caulobacter crescentus holdfast: identification of holdfast attachment complex genes.
Caulobacters are biofilm bacteria that attach to surfaces via a holdfast, an adhesive expressed at discrete cell surface sites. We have described a cluster of at least three genes involved in the adhesive attachment of the holdfast of Caulobacter crescentus CB2A to the cell, analyzing the sequence of two genes, hfaAB. Here we report hfaC and a fourth open reading frame, hfaD. hfaC predicts a protein of 41 kDa homologous to ATP-binding transport-related proteins, with ChvD of Agrobacterium tumefaciens as best match. HfaD is predicted to be 28 kDa with three membrane spanning regions. hfaA, hfaC, and hfaD were expressed in Escherichia coli; Western analysis with antisera against a holdfast-enriched preparation indicated HfaA was likely holdfast-associated. Cumulative findings predict HfaA and HfaB are developmentally regulated and one or both enhance hfaC transcription, HfaA is a mediator of adhesion, possibly between holdfast and a membrane-bound HfaD, and HfaC mediates export of an unidentified component required for holdfast attachment.
Amino Acid Sequence↗
A controlled study of ranitidine for the prevention of recurrent hemorrhage from duodenal ulcer.
BACKGROUND: Hemorrhage is the most common complication of duodenal ulcer disease, but there is little information about the effectiveness and safety of long-term maintenance therapy with histamine H2-receptor blockers. METHODS: We conducted a double-blind study in patients with endoscopically documented hemorrhage from duodenal ulcers. Patients were randomly assigned to maintenance therapy with ranitidine (150 mg at night) or placebo and were followed for up to three years. Endoscopy was performed at base line (to document that the ulcers had healed), at exit from the study, and when a patient had persistent ulcer symptoms unrelieved by antacids or had gastrointestinal bleeding. Symptomatic relapses without bleeding were treated with ranitidine; if the ulcer healed within eight weeks, the patient resumed taking the assigned study medication. RESULTS: The two groups were similar at entry, which usually occurred about three months after the index hemorrhage. After a mean follow-up of 61 weeks, 3 of the 32 patients treated with ranitidine had recurrent hemorrhage, as compared with 12 of the 33 given placebo (P < 0.05). Half the episodes of recurrent bleeding were asymptomatic. One patient in the ranitidine group withdrew from the study because of asymptomatic thrombocytopenia during the first month. CONCLUSIONS: For patients whose duodenal ulcers heal after severe hemorrhage, long-term maintenance therapy with ranitidine is safe and reduces the risk of recurrent bleeding.
Double-Blind Method↗
Readability of the childhood immunization information forms.
OBJECTIVE: To compare the reading level required to understand childhood immunization information forms with the reading grade level of an inner-city parent/caretaker population. DESIGN: Descriptive study (parents/caretakers). SETTING: Inner-city pediatric clinic. PARTICIPANTS: One hundred fifty English-speaking, low-income parent/caretakers. INTERVENTIONS: None. MEASUREMENTS/MAIN RESULTS: The reading level of our parent population ranged from grades 2.9 to 13.3, with a median grade level of 6.90. The reading levels required for the three vaccine information pamphlets issued in 1992 by the Centers for Disease Control and Prevention (Atlanta, Ga) averaged 11.1 (approximately at the level of a high school junior). Eighty-six percent of our parents/caretakers did not have a reading level sufficient to cope with the easiest of the forms. CONCLUSIONS: The vaccine information pamphlets require a reading level beyond the capability of the vast majority of our parent population. Therefore, the goal of informed consent clearly is not being met.
Adolescent↗
False positive results in a neuroblastoma screening programme.
Twenty thousand, eight hundred and twenty-nine babies were screened for neuroblastoma at 6 months of age by measuring homovanillic (HVA) and vanillylmandelic (VMA) acid in urine and rationing these to creatinine. Using a "cut off" of the mean + 3 SD, 10 were found to be positive. Two were found on evaluation to have neuroblastoma and in the remaining 8 the raised levels of HVA and/or VMA returned to normal. Only one of the 8 false positive babies was absolutely normal, most having a chronic disorder or illness. Utilising new centiles which relate HVA and VMA to creatinine, only 3 of the 8 would have remained positive, a false positive rate of 0.01%. The false negative rate would have remained unchanged.
Creatinine↗
Translational activity of mouse protamine 1 messenger ribonucleoprotein particles in the reticulocyte and wheat germ cell-free translation systems.
Protamine 1 mRNAs are inactivated by a block to the initiation of translation in early spermatids and are translationally active in late spermatids in mice. To determine whether translation of protamine 1 mRNAs is inhibited by a protein repressor, the translational activity of ribonucleoprotein particles and deproteinized RNAs were compared in the reticulocyte and wheat germ cell-free translation lysates. To isolate RNPs, cytoplasmic extracts of total testes were fractionated by large-pore gel filtration chromatography. Ribonucleoprotein particles in the excluded fractions stimulated synthesis of radiolabeled translation products for protamine 1 about twofold less effectively than deproteinized RNAs in the reticulocyte lysate, but were inactive in the wheat germ lysate. The ability of translationally repressed protamine 1 ribonucleoprotein particles to form initiation complexes with 80S ribosomes in the reticulocyte lysate was also measured. Protamine 1 ribonucleoprotein particles isolated by gel filtration and in unfractionated cytoplasmic extracts of early spermatids were nearly as active in forming initiation complexes as deproteinized mRNAs. The isolation of ribonucleoprotein particles in buffers of varying ionic strength, protease inhibitors, and several other variables had no major effect on the ability of protamine 1 ribonucleoprotein particles to form initiation complexes in the reticulocyte lysate. These results can be explained by artifacts in the isolation or assay of ribonucleoprotein particles or by postulating that protamine 1 mRNAs are inactivated by a mechanism that does not involve protein repressors, such as sequestration.
Animals↗
Pulmonary mechanics during respiratory distress syndrome in the prediction of outcome and differentiation of mild and severe bronchopulmonary dysplasia.
Pulmonary mechanics was prospectively and longitudinally studied in a cohort of 58 infants who suffered from respiratory distress syndrome. The aim was to determine if early compliance and resistance measurements had additional value to simple clinical variables in predicting poor outcome ie nonsurvival or severe bronchopulmonary dysplasia (BPD) at 28 days. Second, we wanted to determine whether and when the recently described type 1 (mild) BPD and type 2 (severe) BPD could be differentiated by means of lung function tests. In a logistic model, neither lung compliance nor pulmonary resistance at days 1 and 4 of life were selected as predictive variables. On the other hand, gestational age and the ventilatory index no. 1 (ventilator frequency x maximal inspiratory pressure) on day 3 were the best early predictors of poor outcome. Type 2 BPD was characterized by a lower lung compliance and a higher pulmonary resistance than type 1 BPD, although the differences were only significant at 28 days. In conclusion, pulmonary function tests were not helpful in the early prediction of poor outcome at 28 days. They might, however, be of value in the follow-up of BPD patients after 28 days.
Age Factors↗
Flat chest in survivors of bronchopulmonary dysplasia.
Pulmonary mechanics as well as chest wall width and depth were measured in 52 1-year-old survivors of newborn lung disease. Of the 52 patients examined, 22 had developed bronchopulmonary dysplasia (BPD). Chest wall depth was significantly less in the patients who survived with development of BPD compared with those who did not develop BPD. Pulmonary resistance and chest wall width-to-depth ratio were significantly increased in the patients with BPD. Because the chest wall of infants is highly compliant, we suggest that the flatter chest in patients with BPD could result from the abnormal pulmonary mechanics.
Bronchopulmonary Dysplasia↗
Radioactive end labeling to determine hydrolytic rates of nuclease mimics.
Radioactive end labeling can be used to determine the hydrolytic rates of nuclease mimics on moderate to long lengths of RNA or DNA. However, the reliability of end labeling as an assay can vary depending on how well the unincorporated label is removed from the labeled RNA or DNA products. Therefore, gel filtration, acid precipitation, membrane diafiltration, and paper chromatography were tested to determine which technique was the most effective at such separation. The results in order of decreasing contamination by [gamma-32P]ATP were gel filtration (40%), acid precipitation (5%), diafiltration (2%), and paper chromatography (1%); and, in order of decreasing loss of RNA, were acid precipitation (30%), diafiltration (11%), gel filtration (10%), and paper chromatography (1%). In order for the resultant radioactive counts to be linearly proportional to the number of cleavage sites, the total ATP in the end-labeling reaction should be in excess of 5'-hydroxyl ends by a factor of 10 or more. Interference by nuclease mimics in the end-labeling reaction should be accounted for by including the mimics when developing a standard curve based on known concentrations of 5'-hydroxyl ends.
Chromatography, Gel↗
The effects of fibroblast growth factors in long-term primary culture of dystrophic (mdx) mouse muscle myoblasts.
A reliable method for the primary culture of undifferentiated skeletal muscle cells is a prerequisite for the success of therapeutic strategies for Duchenne and Becker muscular dystrophies involving gene therapy. We have developed conditions for the long-term culture of both dystrophic and normal mouse muscle explants and have now successfully cultured both dystrophic and nondystrophic muscle satellite cells continuously for up to 18 months with minimal loss of stem cell phenotype and retention of the expression of muscle cell markers and the ability to fuse at high serum levels. Optimal culture conditions depend on both the age of the animal and the type of muscle explanted, but the majority of skeletal muscle explants produce large numbers of satellite cells within 4-10 days of explanting when cultured in Dulbecco's modified Eagle's medium/Ham's F12 medium supplemented with high levels of fetal calf serum (10-20%). A small proportion of explants will produce outgrowth when placed into serum-free medium and assay of the conditioned medium from these explants shows that they release large amounts of FGF-like activity(s) when compared to nonoutgrowing explants. This process can be augmented by the addition of acidic, but not basic, FGF. Cultures of both dystrophic and nondystrophic muscle grow predominantly as monomorphic rounded cells which stain positively with antibodies specific for skeletal fast muscle actin, myosin, and desmin. In the absence of substantial fibroblast cell contamination, these cells frequently form end-to-end connections and, under permissive conditions, they will fuse to form characteristic myotubes. A major difference observed between dystrophic and normal skeletal muscle explants was the reduction in fibroblast-like cell outgrowth of dystrophic explants.
Animals↗
Doxycycline reduction of F-actin content of human neutrophils and fibroblasts.
We and others have shown that tetracyclines inhibit leukocyte adherence, migration, and phagocytosis, functions presumed to involve actin microfilament metabolism. In this study we investigated the influence of a tetracycline (doxycycline, Dc) on neutrophil and fibroblast actin metabolism. Human neutrophils and fibroblasts were pretreated with Dc or cytochalasin B (cB), stimulated with either the chemotactic peptide FMLP or phorbol myristate acetate (PMA), and the changes in phalloidin conjugate, associated F-actin were followed microscopically or quantified fluorometrically. Doxycycline suppressed, in a dose-related manner, the rise in F-actin content of neutrophils that normally follows their activation with either FMLP or PMA. Cytochalasin B had a similar affect on actin microfilament synthesis. Incubation of fibroblasts in Dc led to a loss of actin microfilaments and caused flattened adherent cells to round up and detach. Both Dc and cB also inhibited Con A-induced acceptor capping on neutrophils, a phenomenon known to be dependent on the presence of intact actin microfilaments. The data show that both Dc and cB influence actin metabolism and suggest they do so by differing mechanisms.
Actins↗
Interference by lubricating jelly in ELISA assay for pepsin in gastric juice samples.
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Cellulose↗
A randomized trial of intravenous heparin in conjunction with anistreplase (anisoylated plasminogen streptokinase activator complex) in acute myocardial infarction: the Duke University Clinical Cardiology Study (DUCCS) 1.
OBJECTIVES: We designed a randomized trial to evaluate the effects of heparin administration in conjunction with anistreplase (anisoylated plasminogen streptokinase activator complex [APSAC]) on arterial patency and clinical end points. BACKGROUND: The role of conjunctive intravenous heparin therapy with APSAC has not been tested despite the recommendations that intravenous heparin should be used. METHODS: Four hours after APSAC administration, 250 patients with acute myocardial infarction were randomly assigned to receive 325 mg of either aspirin alone or aspirin and a continuous infusion of heparin (15 IU/kg body weight per h). Clinical ischemic events and bleeding complications were monitored. On hospital day 5, coronary arteriography and left ventriculography were performed. RESULTS: The primary end point of the trial (the combined outcome of death, reinfarction, recurrent ischemia and occlusion of the infarct-related artery) occurred in 42% of the heparin-treated group versus 43% of the group treated without heparin (p = 0.94). A patent infarct-related artery was present in 80% of the patients treated with heparin and in 73% of those treated without heparin (p = 0.26). Left ventricular function, as measured by ejection fraction, was well preserved in both groups (52% vs. 50.5%, respectively, p = 0.29). The overall bleeding rate was higher in patients with (32%) than without (17.2%) heparin (p = 0.006). CONCLUSIONS: Weight-adjusted intravenous heparin therapy after APSAC in acute myocardial infarction does not reduce the combined incidence of death, reinfarction, recurrent ischemia and occlusion of the infarct-related artery. Furthermore, withholding intravenous heparin therapy is associated with a 46% reduction in bleeding complications. Our findings do not support the addition of intravenous heparin after APSAC therapy, as currently recommended, and suggest that a strategy of withholding heparin is simpler and safer and does not place the patient at increased risk for ischemic complications after myocardial infarction.
Aged↗
Endothelial seeding of polytetrafluoroethylene femoral popliteal bypasses: the failure of low-density seeding to improve patency.
PURPOSE: We compared 66 seeded polytetrafluoroethylene and 53 autologous vein grafts to determine whether endothelial seeding could improve the patency of polytetrafluoroethylene femoral popliteal bypass grafts and to determine whether endothelial seeding could be performed consistently in multiple institutions. METHODS: Nine surgeons at four hospitals randomized patients to receive either a seeded polytetrafluoroethylene or a vein graft, but if no satisfactory vein (n = 26) existed, an "obligatory" seeded polytetrafluoroethylene graft was used. RESULTS: Scanning electron microscopy confirmed satisfactory initial attachment of endothelium on the discarded ends of the grafts. Patency was compared with the use of log rank analysis and revealed better patency in vein grafts at 30 months (vein = 91.6% +/- 4.1%; seeded polytetrafluoroethylene = 37.8% +/- 9.4%; p = 0.006). Failed grafts revealed anastomotic hyperplasia. CONCLUSIONS: (1) Vein graft patency was better than seeded polytetrafluoroethylene grafts; (2) seeding did not improve patency in below-the-knee bypasses as suggested by pilot studies; (3) the failure of seeded grafts was associated with anastomotic hyperplasia but not with the failure of initial endothelial attachment; and (4) each institution reported similar results.
Blood Vessel Prosthesis↗
P53 mutation in a series of epithelial ovarian cancers from the U.K., and its prognostic significance.
In an initial study of 20 fresh ovarian tumour samples, we compared the immunohistochemical positivity of staining of the p53 protein with the presence of missense mutations of the p53 gene. This revealed a prevalence of 50% with a perfect correlation between mutation and immunohistochemical staining. Detection of the p53 protein by immunohistochemistry was, therefore, used as a reliable indicator for the presence of P53 mutation, and was applied to a study of an archival series of 93 ovarian tumours. Positive immunostaining of the p53 protein was observed in 47% of this series. Cox regression was used to assess whether various clinical variables and P53 mutation were related to survival. As a result, it was found that positive staining of the p53 protein was independent of age, tumour differentiation, tumour type, though possibly not stage. There was some evidence that p53 positivity was associated with reduced survival after adjusting for other variables, but the result was not statistically significant.
Biomarkers, Tumor↗