The H2TH-like motif of the Escherichia coli multifunctional protein KsgA is required for DNA binding involved in DNA repair and the suppression of mutation frequencies

[Background] DNA oxidatively damaged by reactive oxygen species is repaired by base excision repair (BER) pathway proteins, with DNA glycosylases removing damaged or mismatched bases in the first step of BER. KsgA is a multifunctional protein that exhibits the activities of two enzymes, DNA glycosylase and rRNA dimethyltransferase. The structure-function relationship of the KsgA protein in cellular DNA repair remains unclear because the domains required for KsgA to recognize DNA have not been identified. [Purpose] To clarify the mechanisms by which KsgA recognizes damaged DNA and to identify the DNA-binding site, which exists in KsgA. [Methods] A structural analysis and in vitro DNA-protein binding assay were performed. The C-terminal function of the KsgA protein was investigated in vitro and in vivo. [Results] The 3D conformations of KsgA, MutM, and Nei were compared at UCSF Chimera. The root mean square deviation of KsgA (214-273) and MutM (148-212) and that of KsgA (214-273) and Nei (145-212) were 1.067 and 1.188 Å, both less than 2 Å, suggesting that the C terminal of KsgA is spatially similar to the H2TH domains of MutM and Nei. The full-length KsgA protein and KsgA lacking 1-8 or 214-273 amino acids were purified and used in gel mobility shift assays. KsgA exhibited DNA-binding activity, which was lost in the C-terminally deleted KsgA protein. Spontaneous mutation frequency was measured using a mutM mutY ksgA-deficient strain, and the results obtained showed that the mutation frequency was not suppressed by KsgA lacking the C-terminal region, whereas it was in KsgA. To assess dimethyltransferase activity, kasugamycin sensitivity was assessed in wild-type and ksgA-deficient strains. Plasmids carrying the full-length ksgA gene and C-terminal deletion gene were introduced into ksgA-deficient strains. KsgA lacking the C terminus restored dimethyltransferase activity in the ksgA-deficient strain as well as KsgA. [Conclusion] The present results confirmed that one enzyme exhibited two activities and revealed that the C-terminal (214-273) amino acids of KsgA were highly similar to the H2TH structural domain, exhibited DNA-binding activity, and inhibited spontaneous mutations. This site is not essential for dimethyltransferase activity

Sol–gel-entrapped pH indicator for monitoring pH variations in cementitious materials:

Sensors for pH evaluation of concrete were made by a sol–gel process with alizarin yellow as pH indicator. The optical absorbance was measured with a visible spectrophotometer coupled with optical fibers. Results showed that the sensors had good reversibility, reproducibility, and fast response time

Case report: Autonomic and endocrine response in the process of brain death in a child with hypoxic-ischemic brain injury

BackgroundThe causes of brain death include cerebral herniation and brainstem ischemia. Neuroendocrine failure or a series of autonomic nervous system disorders are clinically recognized in the transition to brain death among patients with critical brain injuries. An accurate evaluation of these physiologic instabilities and biomarkers is essential to assess the severity and prognosis of pediatric brain injury as well as to initiate supportive care. This case report presents a detailed evaluation of the autonomic nervous system and endocrine function during the transition to brain death in infantile hypoxic-ischemic brain injury by analyzing the heart rate variability and endocrine status.Case PresentationA 1-year-old previously healthy boy went into cardiac arrest after choking on a toy at home. Although spontaneous circulation returned 60 min after cardiopulmonary resuscitation, no cerebral activity or brainstem reflexes were observed after 18 hospital days. The heart rate variability was assessed by analyzing the generic electrocardiogram data. Rapid spikes or drops in the total power of the heart rate variability, accompanied by a cortisol surge, as well as an alternating surge of high- and low-frequency domain variables were detected in the process of brain death.ConclusionThe heart rate variability assessment combined with endocrine provides a better understanding of the clinical course of patients undergoing brain death. It accurately detects the loss of brainstem function, which allows physicians to provide the appropriate supportive care

Computed tomographic arteriography in the diagnosis of hepatocellular carcinoma.

Computed tomographic arteriography (CTA) was performed in 30 patients with hepatocellular carcinoma (HCC). Detection of HCC by CTA was compared with that of conventional celiac or hepatic arteriography. CT scanning was performed immediately, 30 seconds and 1 min after an injection of 5 to 10 ml of contrast medium into the common or proper hepatic artery. Repeated infusions allowed whole liver sections to be visualized. HCC was localized in 28 of the 30 patients by conventional arteriography, with CTA detecting the masses in 27 of the 28 patients. CTA imaging presented the tumor mass in 1 of the 2 patients missed by arteriography. Conventional arteriography delineated the boundaries of HCC in 15 (50%) of the 30 patients. CTA clearly delineated the masses in 26 (87%) of the 30 patients including 11 patients in which the tumor borders were obscure by conventional arteriography. HCC lesions smaller than 1 cm in diameter were detected only by CTA in 6 (20%) of the patients. It was concluded that CTA is both useful and necessary in the demarcation of small HCC masses.</p