Crystal Structure of LysB4, an Endolysin from Bacillus cereus-Targeting Bacteriophage B4

Endolysins are bacteriophage-derived enzymes that hydrolyze the peptidoglycan of host bacteria. Endolysins are considered to be promising tools for the control of pathogenic bacteria. LysB4 is an endolysin produced by Bacillus cereus-infecting bacteriophage B4, and consists of an N-terminal enzymatic active domain (EAD) and a C-terminal cell wall binding domain (CBD). LysB4 was discovered for the first time as an Lalanoyl-D-glutamate endopeptidase with the ability to breakdown the peptidoglycan among B. cereus-infecting phages. To understand the activity of LysB4 at the molecular level, this study determined the X-ray crystal structure of the LysB4 EAD, using the full-length LysB4 endolysin. The LysB4 EAD has an active site that is typical of LAS-type enzymes, where Zn2+ is tetrahedrally coordinated by three amino acid residues and one water molecule. Mutational studies identified essential residues that are involved in lytic activity. Based on the structural and biochemical information about LysB4, we suggest a ligand-docking model and a putative endopeptidase mechanism for the LysB4 EAD. These suggestions add insight into the molecular mechanism of the endolysin LysB4 in B. cereus-infecting phages.

Clinical characteristics of diabetic ketoacidosis in users and non-users of SGLT2 inhibitors

AIM

This study investigated the clinical characteristics of diabetic ketoacidosis (DKA) and compared the DKA characteristics between patients treated with and without SGLT2 inhibitors.

METHODS

Data were collected from patients aged ≥ 18 years admitted for DKA at nine centres in Korea between September 2014 and April 2017. The electronic medical records of these subjects were retrospectively reviewed. Based on their history of medications taken before admission, subjects were classified as either users or non-users of SGLT2 inhibitors and their clinical characteristics of DKA were compared.

RESULTS

During the study, the main subtype of DKA episodes (n = 523) was identified as type 2 diabetes (51%). Average hospitalization duration was 11 days, and average intensive care unit (ICU) time was 2.5 days. The in-hospital mortality rate was 3%, but no users of SGLT2 inhibitors died during DKA treatment. In patients taking SGLT2 inhibitors (n = 15), DKA manifested at 124 days, on average, after starting the inhibitors (range: 7-380 days). Also, SGLT2 inhibitors users had significantly lower plasma glucose levels (413 mg/dL) compared with non-users (554 mg/dL), and longer ICU stays (4 vs. 2 days; P = 0.019).

CONCLUSION

In this report of recent data on the clinical features of DKA in Korea, patients using SGLT2 inhibitors needed longer treatment in ICUs compared with non-users and had lower levels of blood glucose, whereas DKA associated with SGLT2 inhibitors was rare.

Silencing of ATPase family AAA domain-containing protein 2 inhibits migration and invasion of colorectal cancer cells

Colorectal cancer is one of the most common malignant tumors with a high rate of distant metastasis, postoperative recurrence and mortality. ATPase family AAA domain-containing protein 2 (ATAD2), a member of ATPase family, is highly expressed in various cancers, including colorectal cancer. However, whether ATAD2 plays a role in the migration and invasion of colorectal cancer cells remains unknown. In this study, we established ATAD2 knockdown in colorectal cancer cell lines by RNA interference and found that silencing of ATAD2 inhibited the migration and invasion ability of Caco-2 and SW-480 cells. Moreover, ATAD2 silencing suppressed epithelial-mesenchymal transition (EMT), and reduced the expression and enzymatic activity of matrix metalloproteinases (MMPs) in Caco-2 and SW-480 cells. In summary, our results suggest that silencing of ATAD2 inhibits migration and invasion of colorectal cancer cells by suppressing EMT and decreasing the activity of MMPs. Hence, ATAD2 could be considered as a novel molecular marker of metastatic colorectal cancer, and it may provide new insights for clinical diagnosis and treatment of colorectal cancer.

Long-term immunogenicity and immune persistence of live attenuated and inactivated hepatitis a vaccines: a report on additional observations from a phase IV study

Both live attenuated (HA-L) and inactivated (HA-I) hepatitis A vaccine were licensed for routine use in China. Although phase 1, 2 and 3 clinical studies of both vaccines have been completed, further systematic evaluation of their immunogenicity and immunological persistence under phase 4 clinical studies in a wide range of conditions and involving large populations is necessary. A phase IV clinical trial (NCT02601040) was performed in 9000 participants over 18 months of age. Geometric mean concentrations (GMCs) and seroconversion rates (SRs) were compared at five time points during 3 years for 1800 individuals among them. The SRs of HA-L and HA-I were 98.08% (95% CI 95.59%-99.38%) and 99.64% (95% CI 98.93%-100.00%) respectively 28 days after administration of the first dose, and remained at 97.07% (95% CI 94.31%-98.73%) or above and 96.73% (95% CI 94.07%-98.42%) or above respectively during the following 3 years. The GMCs for both the HA-L and HA-I groups showed that both vaccines elicited high anti-HAV titres, considerably more than the threshold of protection needed against HAV infection in humans, and these titres were sustained. Hence, both HA-I and HA-L vaccines could provide an excellent long-term protective effect, and supported the routine use of both vaccines.

A J-shaped relation of BMI and stroke: Systematic review and dose-response meta-analysis of 4.43 million participants

BACKGROUND AND AIM

Many studies have shown increased risk of stroke with greater adiposity as measured by body mass index (BMI), but questions remain about the shape of the dose-response relation. We conducted a systematic review and meta-analysis of prospective studies to clarify the strength and shape of the dose-response relation between BMI and risk of stroke.

METHODS AND RESULTS

PubMed and Embase databases were searched for articles published up to May 11, 2018. Random-effects generalized least-squares regression models were used to estimate study-specific dose-response association, and restricted cubic splines were used to model the association. We included reports of 44 prospective cohort studies describing 102 466 incident cases among 4 432 475 participants. With a 5-unit increment in BMI, the summary relative risk for stroke incidence was 1.10 (95% confidence interval, 1.06 to 1.13; I² = 88.0%). The dose-response relation was J-shaped (P_{non-linearity} <0.001). The risk was not increased at the low BMI range (<24 kg/m²), but was increased within the high BMI range (>25 kg/m²).

CONCLUSION

Both overweight and obesity increase the risk of stroke with a J-shaped dose-response relation, and the nadir of the curve was observed at BMI 23-24 kg/m².

De novo mutations of STXBP1 in Chinese children with early onset epileptic encephalopathy

To detect syntaxin-binding protein 1 (STXBP1) mutations in Chinese patients with early onset epileptic encephalopathy (EOEE) of unknown etiology. Targeted next-generation sequencing was used to identify STXBP1 mutations in 143 Chinese patients with EOEE of unknown etiology. A filtering process was applied to prioritize rare variants of potential functional significance. Then Sanger sequencing was employed to validate the parental origin of the variants. Detailed clinical and genetic data were collected for 9 STXBP1-positive patients. Eight de novo heterozygous STXBP1 mutations were identified in 9 patients; 5 were novel mutations (c.1155delC, c.1030-1G>A, c.217G>C, c.268G>C, c.1480_1481 insT) and 3 were previously reported (c.1216C> T, c.1217G>A [2 cases], c.875G>A). Two patients had Ohtahara syndrome and 1 had West syndrome at onset, whereas the other 6 presented with EOEE that did not fit a specific recognized epilepsy syndrome. Six of these patients later evolved to West syndrome. All but 2 cases were prescribed more than 2 antiepileptic drugs (AEDs) plus other regimens. Four subjects showed good responses to levetiracetam (LEV) alone or in combination with other AEDs, and one case (1/3) achieved complete freedom from seizures with a ketogenic diet (KD). All patients exhibited severe to profound global developmental delay. Five novel heterozygous de novo STXBP1 mutations were discovered in patients with EOEE from China. STXBP1 mutational analysis should be performed in cases of EOEE of unknown etiology. LEV as monotherapy or adjunctive therapy with other regimens, as well as KD should be considered for management of this patient group.

Measuring Attitudes About End-of-Life Care: Evaluation of a Modified Version of the Hospice Philosophy Scale

The Hospice Philosophy Scale (HPS) is the only scaled instrument that measures health professionals’ attitudes about end-of-life care consistent with the hospice philosophy. This study tested the properties of a modified version of the HPS to provide preliminary validation data on internal consistency, convergent validity, and factorability in a broad population of adults. A cross-sectional telephone survey designed to assess the general population’s attitudes regarding hospice use was administered. exploratory factor analysis elicited an eight-item instrument (HPS-8). The HPS-8 produced a Cronbach’s alpha of .73 and demonstrated sufficient convergent validity, including positive associations with a scale measuring the importance of relevant end-of-life issues ( r = .41, p < .001), a personal preference for hospice (ρ = .36, p < .001), and, among those who had experienced hospice care, satisfaction with hospice care (ρ = .28, p < .01). Our evidence suggests the HPS-8 is a reliable and valid instrument for use with a general adult population.

A Novel Tetrameric Assembly Configuration in VV2_1132, a LysR-Type Transcriptional Regulator in Vibrio vulnificus

LysR-type transcriptional regulators (LTTRs) contain an N-terminal DNA binding domain (DBD) and a C-terminal regulatory domain (RD). Typically, LTTRs function as homotetramers. VV2_1132 was identified in Vibrio vulnificus as an LTTR that is a homologue of HypT (also known as YjiE or QseD) in Escherichia coli. In this study, we determined the crystal structure of full-length VV2_1132 at a resolution of 2.2 Å, thereby revealing a novel combination of the domains in the tetrameric assembly. Only one DBD dimer in the tetramer can bind to DNA, because the DNA binding motifs of the other DBD dimer are completely buried in the tetrameric assembly. Structural and functional analyses of VV2_1132 suggest that it might not perform the same role as E. coli HypT, indicating that further study is required to elucidate the function of this gene in V. vulnificus. The unique structure of VV2_1132 extends our knowledge of LTTR function and mechanisms of action.

Greenland records of aerosol source and atmospheric lifetime changes from the Eemian to the Holocene

The Northern Hemisphere experienced dramatic changes during the last glacial, featuring vast ice sheets and abrupt climate events, while high northern latitudes during the last interglacial (Eemian) were warmer than today. Here we use high-resolution aerosol records from the Greenland NEEM ice core to reconstruct the environmental alterations in aerosol source regions accompanying these changes. Separating source and transport effects, we find strongly reduced terrestrial biogenic emissions during glacial times reflecting net loss of vegetated area in North America. Rapid climate changes during the glacial have little effect on terrestrial biogenic aerosol emissions. A strong increase in terrestrial dust emissions during the coldest intervals indicates higher aridity and dust storm activity in East Asian deserts. Glacial sea salt aerosol emissions in the North Atlantic region increase only moderately (50%), likely due to sea ice expansion. Lower aerosol concentrations in Eemian ice compared to the Holocene are mainly due to shortened atmospheric residence time, while emissions changed little.

Past climate changes in Greenland ice were accompanied by large aerosol concentration changes. Here, the authors show that by correcting for transport effects, reliable source changes for biogenic aerosol from North America, sea salt aerosol from the North Atlantic, and dust from East Asian deserts can be derived.

Abstract P4-02-10: Breast cancer surveillance in high-risk women with dynamic contrast-enhanced magnetic resonance imaging every 6 months: Results from a single institution study

Purpose: To develop a novel approach for early detection of breast cancer and examine molecular features of screen detected cancers in prospectively ascertained high-risk women undergoing semi-annual dynamic contrast-enhanced breast magnetic resonance imaging (DCE-MRI) for women at high genetic risk.

Background: Women with a personal or family history of breast cancer and genetic mutation carriers of BRCA1 and BRCA2 have a higher than normal risk of breast cancer. An intensified screening surveillance regimen is an early detection strategy in high-risk women. The American Cancer Society recommends annual DCE-MRI in addition to annual mammogram based off several pivotal screening studies that demonstrated improved sensitivity and cancer detection rates and decreased interval cancer rates with the addition of annual DCE-MRI. Questions remain regarding the optimal screening modality and interval regimen in these high-risk women.

Methods: Between 2004 and 2016, we assembled a prospective cohort of high-risk women undergoing semi-annual DCE-MRI and annual mammography. To be eligible, women had a lifetime breast cancer risk &gt;20% and/or tested positive for a pathogenic mutation using a cancer gene panel including BRCA1, BRCA2, CDH1, PALB2, CHEK2 and other cancer susceptibility genes in the DNA repair pathway. Somatic mutation events in screen-detected tumors were investigated using UW-OncoPlex cancer gene panel using DNA extracted from FFPE shavings.

Results: 295 women were recruited to the study; 44% of the study participants had pathogenic mutations in BRCA1 or BRCA2 genes. At a median follow-up of 3.3 years (range 0-12 years), 3 DCIS and 13 early stage invasive breast cancers were detected, of which 14 occurred in subjects with identifiable pathogenic mutations (11 BRCA1, 2 BRCA2, 1 CDH1). The incidence rate is 1.3% in all subjects, but 3.5 % per year in BRCA1 carriers. DCE-MRI identified all 13 invasive cancers at a mean size of 0.61 cm (range 0.1-1.0 cm); none had lymph node metastasis. No interval cancers occurred. In addition, 7 of the breast cancers were detected on DCE-MRI imaging obtained at the 6 months screening interval; they would be interval cancers if only annual screening were implemented. There was very little DNA for somatic mutation testing in the majority of cases. However, as expected, there was heterogeneity in the spectrum of mutations but the most commonly somatically mutated gene in the early cancers was TP53.

Conclusions: DCE-MRI every 6 months performed well for early detection of invasive breast cancer in high-risk women, accomplishing the ultimate goal of breast cancer screening—detecting node-negative, invasive tumors less than 1 cm. Semi-annual DCE-MRI performed especially well in BRCA1 mutation carriers at risk for the most aggressive subtype of breast cancer. Further interventional studies evaluating this novel screening approach are warranted to personalize breast cancer risk assessment and prevention.

Citation Format: Whitaker K, Guindalini R, Abe H, Sheeth D, Huo D, Hong S, Churpek J, Verp M, Obeid E, Zheng Y, Amico A, Yoshimatsu T, Olopade O. Breast cancer surveillance in high-risk women with dynamic contrast-enhanced magnetic resonance imaging every 6 months: Results from a single institution study [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P4-02-10.