P8 Contributions of neural crest and paraxial mesoderm to craniofacial morphogenesis in the chick embryo.
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Journal Article↗
Biomedical subjects
S Thomas
Publications and source records attributed to S Thomas.
Effect of ecNOS polymorphisms and coronary artery disease upon exhaled nitric oxide.
Exhaled nitric oxide (eNO) is thought to arise principally from the airway epithelium. NO regulates smooth muscle tone, and abnormal activity of NO synthase has been implicated in coronary artery disease (CAD). Polymorphisms of endothelial constitutive NO synthase (ecNOS) may affect NO generation and be associated with CAD. It was hypothesised that a polymorphism, such as the ecNOS intron 4 polymorphism (ecNOS4a), affects the levels of eNO via airway epithelial NOS. eNO levels were measured in 53 patients with ischaemic chest pain who had previously been genotyped for ecNOS polymorphisms, with sample enrichment for the ecNOS4a allele. Subjects were also assessed for two other ecNOS polymorphisms (T-786C substitution in the promoter region, and G5557T in exon 7), variably associated with vascular disease. Those homozygous for the 'a' allele (ecNOS4a/a) had a lower mean eNO (9.0 ppb) than those who were heterozygous (ecNOS4a/b, 13.6 ppb), who in turn had a lower level than those homozygous for the wild-type ecNOS4b/b (16.1 ppb). No association of eNO levels was found with the other polymorphisms. Levels of eNO remained significantly lower in the ecNOSa/a subjects than in the ecNOSa/b and ecNOSb/b subjects, even when controlled for angiographic CAD, and smoking habit. In addition, all subjects with CAD had a significantly lower mean eNO (12.1 ppb) than subjects without angiographic CAD (19.9 ppb). In this selected population low levels of eNO were thus associated with presence of the ecNOS4a allele and also with CAD.
Administration, Oral↗
Aminoborohydrides. 14. Lithium aminoborohydrides in the selective reduction or amination of alkyl methanesulfonate esters.
Lithium aminoborohydride (LAB) reagents initiate the amination or reduction of alkyl methanesulfonate esters, as dictated by reaction conditions. Alkyl methanesulfonate esters treated with unhindered LABs provide tertiary amines in excellent yield. Reduction to the corresponding alkane is achieved using a hindered LAB reagent or by forming the highly reactive Super-Hydride reagent in situ using LAB and a catalytic amount of triethylborane. The reduction methodology disclosed herein is a safe and convenient alternative to existing synthetic methods. [reaction: see text]
Journal Article↗
Two week rule for cancer referrals. Reducing waiting times from diagnosis to treatment might be more effective.
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Humans↗
Early enteral feeding versus "nil by mouth" after gastrointestinal surgery: systematic review and meta-analysis of controlled trials.
OBJECTIVE: To determine whether a period of starvation (nil by mouth) after gastrointestinal surgery is beneficial in terms of specific outcomes. DESIGN: Systematic review and meta-analysis of randomised controlled trials comparing any type of enteral feeding started within 24 hours after surgery with nil by mouth management in elective gastrointestinal surgery. Three electronic databases (PubMed, Embase, and the Cochrane controlled trials register) were searched, reference lists checked, and letters requesting details of unpublished trials and data sent to pharmaceutical companies and authors of previous trials. MAIN OUTCOME MEASURES: Anastomotic dehiscence, infection of any type, wound infection, pneumonia, intra-abdominal abscess, length of hospital stay, and mortality. RESULTS: Eleven studies with 837 patients met the inclusion criteria. In six studies patients in the intervention group were fed directly into the small bowel and in five studies patients were fed orally. Early feeding reduced the risk of any type of infection (relative risk 0.72, 95% confidence interval 0.54 to 0.98, P=0.036) and the mean length of stay in hospital (number of days reduced by 0.84, 0.36 to 1.33, P=0.001). Risk reductions were also seen for anastomotic dehiscence (0.53, 0.26 to 1.08, P=0.080), wound infection, pneumonia, intra-abdominal abscess, and mortality, but these failed to reach significance (P>0.10). The risk of vomiting was increased among patients fed early (1.27, 1.01 to 1.61, P=0.046). CONCLUSIONS: There seems to be no clear advantage to keeping patients nil by mouth after elective gastrointestinal resection. Early feeding may be of benefit. An adequately powered trial is required to confirm or refute the benefits seen in small trials.
Anastomosis, Surgical↗
Vpr is preferentially targeted by CTL during HIV-1 infection.
The HIV-1 accessory proteins Vpr, Vpu, and Vif are essential for viral replication, and their cytoplasmic production suggests that they should be processed for recognition by CTLs. However, the extent to which these proteins are targeted in natural infection, as well as precise CTL epitopes within them, remains to be defined. In this study, CTL responses against HIV-1 Vpr, Vpu, and Vif were analyzed in 60 HIV-1-infected individuals and 10 HIV-1-negative controls using overlapping peptides spanning the entire proteins. Peptide-specific IFN-gamma production was measured by ELISPOT assay and flow-based intracellular cytokine quantification. HLA class I restriction and cytotoxic activity were confirmed after isolation of peptide-specific CD8(+) T cell lines. CD8(+) T cell responses against Vpr, Vpu, and Vif were found in 45%, 2%, and 33% of HIV-1-infected individuals, respectively. Multiple CTL epitopes were identified in functionally important regions of HIV-1 Vpr and Vif. Moreover, in infected individuals in whom the breadth of HIV-1-specific responses was assessed comprehensively, Vpr and p17 were the most preferentially targeted proteins per unit length by CD8(+) T cells. These data indicate that despite the small size of these proteins Vif and Vpr are frequently targeted by CTL in natural HIV-1 infection and contribute importantly to the total HIV-1-specific CD8(+) T cell responses. These findings will be important in evaluating the specificity and breadth of immune responses during acute and chronic infection, and in the design and testing of candidate HIV vaccines.
Amino Acid Sequence↗
[Erectile dysfunction: prevalence and effects on the quality of life: the Boxmeer study].
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Erectile Dysfunction↗
3-(4-Fluoropiperidin-3-yl)-2-phenylindoles as high affinity, selective, and orally bioavailable h5-HT(2A) receptor antagonists.
The development of very high affinity, selective, and bioavailable h5-HT(2A) receptor antagonists is described. By investigation of the optimal position for the basic nitrogen in a series of 2-phenyl-3-piperidylindoles, it was found that with the basic nitrogen at the 3-position of the piperidine it was not necessary to further substitute the piperidine in order to obtain good binding at h5-HT(2A) receptors. This meant the compounds no longer had high affinity at the IKr potassium channel, an issue with previous series of 2-aryl-3-(4-piperidyl)indoles. Improvements could be made to oral bioavailability in this series by reduction of the pK(a) of the basic nitrogen, by adding a fluorine atom to the piperidine ring, leading to 3-(4-fluoropiperidin-3-yl)-2-phenyl-1H-indole (17). Metabolic studies with this compound identified oxidation at the 6-position of the indole as a major route in vitro and in vivo in rats. Blocking this position with a fluorine atom led to 6-fluoro-3-(4-fluoropiperidin-3-yl)-2-phenyl-1H-indole (22), an antagonist with 0.06 nM affinity for h5-HT(2A) receptors, with bioavailability of 80% and half-life of 12 h in rats.
Animals↗
Aminoborohydrides. 12. Novel tandem S(N)Ar amination-reduction reactions of 2-halobenzonitriles with lithium N,N-dialkylaminoborohydrides.
A novel tandem amination-reduction reaction has been developed in which 2-(N,N-dialkylamino)benzylamines are generated from 2-halobenzonitriles and lithium N,N-dialkylaminoborohydride (LAB) reagents. These reactions are believed to occur through a tandem S(N)Ar amination-reduction mechanism wherein the LAB reagent promotes halide displacement by the N,N-dialkylamino group, and the nitrile is subsequently reduced. This one-pot procedure is complimentary to existing synthetic methods and is an attractive synthetic tool for the nucleophilic aromatic substitution of halobenzenes with less nucleophilic amines. The (N,N-dialkylamino)benzylamine products of this reaction are easily isolated after a simple aqueous workup procedure in very good to excellent yields.
Journal Article↗
Differential frequency-dependent regulation of transmitter release by endogenous nitric oxide at the amphibian neuromuscular synapse.
Nitric oxide (NO) is a potent neuromodulator in the CNS and PNS. At the frog neuromuscular junction (nmj), exogenous application of NO reduces neurotransmitter release, and NO synthases (NOSs), the enzymes producing NO, are present at this synapse. This work aimed at studying the molecular mechanisms by which NO modulates synaptic efficacy at the nmj using electrophysiological recordings and Ca(2+)-imaging techniques. Bath application of the NO donors S-nitroso-N-acetylpenicillamine (SNAP) and sodium nitroprusside decreased end plate potential (EPP) amplitude as well as the frequency of miniature EPPs but not their amplitude. Ca(2+) responses elicited in presynaptic terminals by single action potentials were unaffected by NO, but responses evoked by a short train of stimuli were increased. Tonic endogenous production of NO was observed as suggested by the increase in EPP amplitude by bath application of the NO scavenger hemoglobin and the neuronal NOS inhibitor 3-bromo-7-nitroindazole sodium salt. A soluble guanylate cyclase inhibitor, 6-anilino-5,8-quinolinedione (LY-83583), increased EPP amplitude and occluded the effects of the NO donor, suggesting that NO acts via a cGMP-dependent mechanism. High-frequency-induced depression was reduced in the presence of the NO scavenger but not by LY-83583. However, adenosine-induced depression was significantly reduced after bath perfusion of SNAP and in the presence of LY-83583. Our results indicate that NO regulates transmitter release and adenosine-induced depression via a cGMP-dependent mechanism that occurs after Ca(2+) entry and that high-frequency-induced synaptic depression is regulated by NO in a cGMP-independent manner.
Action Potentials↗
Combined use of growth rate correlated and growth rate independent promoters for recombinant glucoamylase production in Fusarium venenatum.
Fusarium venenatum JeRS 325, a strain which produces recombinant glucoamylase under control of a growth rate independent promoter was transformed with a plasmid carrying the Aspergillus niger glucoamylase gene under control of its own growth rate correlated promoter. Some disruption of the original recombinant genes occurred and at pH 5.8 the double transformant did not produce as much glucoamylase as JeRS 325 in batch culture. However, the double transformant still produced as much glucoamylase as JeRS 325 in fed-batch cultures, illustrating the potential for the combined use of growth rate independent and dependent promoters to improve production of recombinant proteins in fed-batch culture systems.
Aspergillus niger↗
Control of rheumatoid arthritis by oral tolerance.
OBJECTIVE: Previous randomized controlled trials for treatment of rheumatoid arthritis (RA) with acid-soluble chicken and bovine type II collagen (CII) have produced conflicting results. This randomized, double-blind, controlled trial examined the therapeutic effect of bovine CII tablets in RA. METHODS: CII tablets were prepared by adsorption onto a lactose base. Patients with a duration of RA of > or = 2 years and who had failed treatment with at least 1 slow-acting drug were recruited, provided that they had active arthritis. Patients were randomly assigned to receive either 0.05 mg, 0.5 mg, or 5 mg of CII or placebo daily for 6 months. All slow-acting drugs were stopped at least 4 weeks before starting CII, although prednisolone was permitted at dosages < 10 mg/day. Clinical assessments were performed at screening and at 0, 1, 4, 8, 12, 16, 20, and 24 weeks of treatment. RESULTS: Fifty-five patients were recruited. Initially, there were no significant differences in mean Disease Activity Scores between groups. At 24 weeks, there was a significant difference (P = 0.041, by Kruskal-Wallis analysis of variance); the major components of this difference were attributable to relatively large decreases in the 0.5 mg CII group (19% of initial values) and to minimal decreases in patients receiving placebo (3% of initial values). Twenty patients had American College of Rheumatology 20% responses; 11 of these were in the 0.5 mg CII group and 3 were in each of the other groups, a significant difference (chi2 = 14.6, P = 0.002). There was no significant difference in any clinical measure between the placebo, 0.05 mg CII, and 5 mg CII groups. There were no side effects associated with CII treatment. CONCLUSION: Treatment with 0.5 mg/day of bovine CII is well tolerated and produces small, but significant, disease improvement in RA. However, the therapeutic window is narrow. The difference between our results and those of other trials may relate to the dose, species, and formulation of the CII.
Administration, Oral↗
Nitric oxide protects the intestine from the damage induced by laparotomy and gut manipulation.
BACKGROUND: The intestine is highly susceptible to free radical-induced damage, and our earlier work has shown that surgical stress induces the generation of oxygen free radicals in enterocytes, resulting in intestinal damage along with ultrastructural changes. Since nitric oxide (NO) is an important mediator of gastrointestinal function, this study looked at the effect of NO on surgical stress-induced intestinal alterations. MATERIALS AND METHODS: Control rats and rats pretreated with the NO donor l-arginine were subjected to surgical stress by opening the abdominal wall and handling the intestine as done during laparotomy. Enterocytes were isolated and homogenate prepared, and the protection offered by l-arginine against damage due to surgical stress was determined and compared with normal controls. Protection to structural as well as functional aspects of the intestine was also examined. RESULTS: Intestinal manipulation affected intestinal structure as assessed by electron microscopy. Functional impairment of the enterocyte was also evident, with increased xanthine oxidase activity resulting in production of superoxide anion. This impairment is more dramatic in the crypt cells. Increased protease activity was also seen following laparotomy and handling. Pretreatment with the NO synthase substrate l-arginine prevented these damaging effects. Arginine protection was abolished in the presence of the NO synthase inhibitor NG-nitro-l-arginine methyl ester, indicating the role of NO. CONCLUSION: Stress in the small intestine due to any surgery can affect enterocyte structure and function. These damaging effects can be prevented by NO, an important modulator of cellular function.
Animals↗
Expression and conservation of processed copies of the RBMX gene.
RBMX and RBMY are members of an ancient pair of genes located on the sex chromosomes that encode RNA-binding proteins involved in splicing. These genes have differentiated and evolved separately on the X and Y Chromosomes. RBMY has acquired a testis-specific function, whereas, as shown here, RBMX is ubiquitously expressed and is subject to X inactivation. We have also found that multiple processed copies of RBMX are present in the human genome. RBMX-like sequences (RBMXLs) located on human Chrs 1, 4, 6, 9 (9p13 and 9p24), 11, 20, and X lack introns and thus probably result from retroposition events. We found RBMXLs to be conserved in primates and great apes at corresponding chromosomal locations, indicating that they arose prior to the divergence of human. Some of the RBMXLs show insertions, deletions, and stop codons, which would probably result in nonfunctional proteins. The RBMXL on Chr 20 is deleted in some individuals. Two of the largely intact RBMXLs, located on Chrs 1 and 9p13, are expressed in different tissues and may encode novel proteins involved in splicing in a tissue-specific manner. The RBMXL located at 9p13 is specifically expressed in testis, and to a lesser extent in brain, and may therefore play a role in testis function. This autosomal, testis-specific copy of RBMX could potentially compensate for RBMX that is presumably inactivated in male germ cells, in a manner analogous to autosomal retroposed copies of other X-linked genes.
Amino Acid Sequence↗
Expression and chromosomal mapping of the mouse smooth muscle calponin gene.
Smooth muscle calponin (Cnn1) is a multifunctional protein whose expression is tightly restricted to differentiated smooth muscle cell (SMC) lineages during embryonic and post-natal life. As such, Cnn1 represents an ideal locus from which to dissect out regulatory elements that control its expression and hence the mature SMC phenotype. Previous work has focused on the expression and chromosomal mapping of the rat and human Cnn1 orthologs. In this report, we describe a unique pattern of Cnn1 expression during the growth and differentiation of BC3H1 cells, a mouse cell line that has transcriptional characteristics of both smooth and skeletal muscle lineages. Actively growing BC3H1 cells exhibit Cnn1 mRNA expression, which is extinguished when these cells are induced to differentiate upon serum withdrawal. Replating differentiated BC3H1 cells restores steady-state Cnn1 mRNA levels. The down-regulation of Cnn1 mRNA during BC3H1 differentiation coincides with the induction of myogenin, a skeletal muscle transcription factor that is not present in SMC lineages. Results from cycloheximide and actinomycin D studies suggest the existence of a labile repressor protein(s) that destabilizes the pool of Cnn1 mRNA and/or silences transcription of the Cnn1 locus. Mapping of the mouse Cnn1 locus to Chr 9, which is homologous to human Cnn1 on 19p13.2 and rat Cnn1 on 8q, suggests no gross rearrangement of this locus in the BC3H1 cell line. These results are the first to show reversible expression of Cnn1 and demonstrate the utility of the BC3H1 muscle cell line as a model system for the further characterization of Cnn1 gene regulation.
Animals↗
Multiple genetic alterations involved in the tumorigenesis of human cholangiocarcinoma: a molecular genetic and clinicopathological study.
PURPOSE: Cholangiocarcinoma (CC) is the second most common malignant tumor in the liver and the molecular genetic alterations involved in the tumorigenesis of CC have not been well studied. PATIENTS AND METHODS: The authors analyzed the loss of heterozygosity (LOH) in four tumor suppressor genes, including the adenomatous polyposis coli (APC) gene, the deleted in colon cancer (DCC) gene, the 8-hydroguanine-specific DNA glycosylase (OGG1) gene, and the p53 gene in 22 surgically resected primary CCs by using microdissection-based PCR amplification and direct DNA sequencing. RESULTS: A total of 19 (86.4%) out of 22 CCs exhibited genetic alterations, of which 11 (57.9%) and eight (42.1%) cases showed one and more than one gene alterations, respectively. The frequency of genetic alterations of the four genes studied ranged in order from high to low as APC (68.8%) > DCC (46.2%) > OGG1 (41.7%) > p53 (37.5%). Based on the pattern of altered genes and their correlation with clinical and pathological parameters, the genetic alterations were classified into three groups: group I: no detectable genetic alterations (n = 3, 13.6%); group II: LOH in APC and/or DCC (n = 9, 40.9%); and group III: LOH in OGG1 and/or p53 occurred separately or combined with LOH in APC and/or DCC (n = 10, 45.5%). The > or = 3-year survival rates between group II and group III are 88.9% and 30%, respectively (P < 0.05). No significant differences were found between genetic alterations and tumor size, tumor type, tumor invasion, TNM staging, and tumor differentiation (P > 0.05). CONCLUSION: Accumulation of multiple genetic alterations are involved in the tumorigenesis of CC, of which genetic alterations of APC and DCC occur at a relatively early stage, and of OGG1 and p53 occur at a relatively late stage during development of CC.
Aged↗
The use of mycophenolate mofetil suspension in pediatric renal allograft recipients.
Mycophenolate mofetil (MMF) is widely used to prevent acute rejection in adults after renal, cardiac, and liver transplantation. This study investigated the safety, tolerability, and pharmacokinetics of MMF suspension in pediatric renal allograft recipients. One hundred renal allograft recipients were enrolled into three age groups (33 patients, 3 months to <6 years; 34 patients, 6 to <12 years; 33 patients, 12 to 18 years). Patients received MMF 600 mg/m2 b.i.d. concomitantly with cyclosporine and corticosteroids with or without antilymphocyte antibody induction. One year after transplantation, patient and graft survival (including death) were 98% and 93%, respectively. Twenty-five patients (25%) experienced a biopsy-proven (Banff grade borderline or higher) or presumptive acute rejection within the first 6 months post-transplantation. Analysis of pharmacokinetic parameters for mycophenolic acid (MPA) and mycophenolic acid glucuronide showed no clinically significant differences among the age groups. The dosing regimen of MMF 600 mg/m2 b.i.d. achieved the targeted early post-transplantation MPA 12-h area under concentration-time curve (AUC0-12) of 27.2 microg h per ml. Adverse events had similar frequencies among the age groups (with the exception of diarrhea, leukopenia, sepsis, and anemia, which were more frequent in the <6 years age group) and led to withdrawal of MMF in about 10% of patients. Administration of MMF 600 mg/m2 b.i.d. is effective in prevention of acute rejection, provides predictable pharmacokinetics, and is associated with an acceptable safety profile in pediatric renal transplant recipients.
Adolescent↗