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CTP Synthetase (CtpS) is a universally conserved and essential metabolic enzyme. While many enzymes form small oligomers, CtpS forms large-scale filamentous structures of unknown function in prokaryotes and eukaryotes. By simultaneously monitoring CtpS polymerization and enzymatic activity, we show that polymerization inhibits activity, and CtpS's product, CTP, induces assembly. To understand how assembly inhibits activity, we used electron microscopy to define the structure of CtpS polymers. This structure suggests that polymerization sterically hinders a conformational change necessary for CtpS activity. Structure-guided mutagenesis and mathematical modeling further indicate that coupling activity to polymerization promotes cooperative catalytic regulation. This previously uncharacterized regulatory mechanism is important for cellular function since a mutant that disrupts CtpS polymerization disrupts E. coli growth and metabolic regulation without reducing CTP levels. We propose that regulation by large-scale polymerization enables ultrasensitive control of enzymatic activity while storing an enzyme subpopulation in a conformationally restricted form that is readily activatable.

The extracts from Psoralea corylifolia Linn. (P. corylifolia) seeds have been shown to display antitumor activity. To date, the prospects of this plant and its active compounds in the treatment of non-small-cell lung cancer (NSCLC) have not been thoroughly studied. In this study, we identified a novel psorachromene compound that displays selective cytotoxic effects on all NSCLC cells tested, including NSCLC cells harboring epidermal growth factor receptor (EGFR) activation mutants (H1975L858R/T790M and H1975-MS35L858R/T790M/C797S ). Psorachromene induces G1 arrest in NSCLC cells harboring wild-type EGFR but induces apoptosis in NSCLC cells harboring activating EGFR mutations. Psorachromene inhibits activated EGFR signaling and kinase activity and suppresses tumor growth of implanted H1975-MS35L858R/T790M/C797S cells in nude mice. Molecular docking analysis revealed that psorachromene could form stronger bonds with mutant EGFR than wild-type EGFR, which might account for the greater cytotoxic effects observed in NSCLC cells harboring activating EGFR mutations (H1975 and H1975-MS35) than wild-type EGFR (A549). In conclusion, it is suggested that psorachromene is an attractive agent to be further explored for its use in the treatment of NSCLC patients harboring EGFR L858R/T790M/C797S. [ABSTRACT FROM AUTHOR]

Background: The CTLA4 gene is involved in the activity of T cells., Aim: To determine the association between Graves' disease (GD) susceptibility and CT60 polymorphism of the CTLA4 gene., Patients: 189 children with GD and 620 healthy controls., Methods: We determined the genotype with restriction fragment length polymorphism and compared results., Results: Genotype G/G was significantly associated with GD (odds ratio [OR] = 1.71, 95% confidence interval [CI] 1.20-2.44, Pc = 0.006); however, allele A could reverse its effect. Allele G was significantly more frequent (OR = 1.61, 95% CI 1.18-2.19, Pc = 0.0049) but allele A (OR = 0.62, 95% CI 0.46-0.85, Pc = 0.0049) and phenotype A (OR = 0.58, 95% CI 0.41-0.83, Pc = 0.006) were less frequent in patients with GD than in controls., Conclusion: The CT60 SNP was associated with susceptibility to GD. The G allele increased the risk of GD.

Background: The incidence of type 1 diabetes (T1D) is increasing rapidly worldwide, predominantly in younger individuals. We developed a checklist of all symptoms of T1D reported in the literature and compared the completeness of the recording of symptoms at initial presentation before and after the checklist was adopted., Methods: We retrospectively reviewed the records of patients newly diagnosed with T1D from January 1, 1979 through September 30, 2006 to assess the presenting features and test the usefulness of a symptom checklist in evaluating the history on presentation. The checklist was incorporated into the records as of October 1, 1994., Results: Of the 304 patients identified, 130 (43%) had checklists in the charts. There were 146 (48%) boys, 98 (32%) who were diagnosed under the age of 6 years, and 198 (65%) presented with diabetic ketoacidosis (DKA). Records with a checklist noted diabetic symptoms that were subtle and easily ignored more often than records without the checklist. As compared with those diagnosed at an older age, patients diagnosed at < or = 6 years were more likely to be male, have DKA and a shorter symptom duration, and report more episodes of preceding viral infection and dyspnea. Patients with DKA also had a shorter symptom duration., Conclusions: A diabetic symptom checklist was helpful in identifying clinical diabetic symptoms and signs which were otherwise easily ignored. Younger children were more likely to have a shorter symptom duration and a higher incidence of DKA.

Background: Type 2 diabetes mellitus (T2DM) in children and adolescents is increasing in incidence worldwide. It is the leading type of newly diagnosed diabetes in Taiwan among school children. T2DM is associated with metabolic syndrome in adults, so we tried to find out if these metabolic disorders are present in children., Methods: From 1989 to 2003, 22 children and adolescents were diagnosed with T2DM in our hospital. Their ages ranged from 8.8 to 17.0 (11.7+/-2.3) years; 6 of them were boys. We compared their clinical characteristics with those of 42 healthy and 237 obese children and adolescents. Physical examination was performed and plasma glucose and serum cholesterol, triglycerides, uric acid, creatinine, HDL-cholesterol, and insulin levels were measured and LDL-cholesterol was calculated. Demographic and laboratory data were compared among the T2DM, obese and control groups., Results: The female: male ratio among the patients was 2.7: 1; 18% were overweight and 68% obese, and 64% had acanthosis nigricans. There were no significant differences between the T2DM and obese groups in terms of biochemistry profiles except for the higher plasma glucose in the T2DM group. Children with T2DM had higher levels of cholesterol and triglycerides but lower levels of HDL-cholesterol compared with healthy children. Among obese children without T2DM, the levels of glucose, triglycerides, uric acid, insulin, HOMA-IR were higher than in the healthy group, and HDL-cholesterol levels were lower., Conclusions: Children with T2DM or obesity should be evaluated for metabolic disorders.