Aquaporin-4 Functionality and Virchow-Robin Space Water Dynamics: Physiological Model for Neurovascular Coupling and Glymphatic Flow.

The unique properties of brain capillary endothelium, critical in maintaining the blood-brain barrier (BBB) and restricting water permeability across the BBB, have important consequences on fluid hydrodynamics inside the BBB hereto inadequately recognized. Recent studies indicate that the mechanisms underlying brain water dynamics are distinct from systemic tissue water dynamics. Hydrostatic pressure created by the systolic force of the heart, essential for interstitial circulation and lymphatic flow in systemic circulation, is effectively impeded from propagating into the interstitial fluid inside the BBB by the tightly sealed endothelium of brain capillaries. Instead, fluid dynamics inside the BBB is realized by aquaporin-4 (AQP-4), the water channel that connects astrocyte cytoplasm and extracellular (interstitial) fluid. Brain interstitial fluid dynamics, and therefore AQP-4, are now recognized as essential for two unique functions, namely, neurovascular coupling and glymphatic flow, the brain equivalent of systemic lymphatics

Identification of the transcriptional regulatory gene of histidase and urocanase in Pseudomonas aeruginosa -Regulation of histidase and urocanase expression-

Pseudomonas aeruginosa is a typical opportunistic bacterial pathogen that can grow under poor nutrient conditions. Histidine utilization as a sole source of carbon and nitrogen is a distinctive feature of P.aeruginosa, which decompose and utilize a variety of nutrients and complex compounds using various catabolite pathways. When wild-type P.aeruginosa PAO1 cells were cultured in minimal medium P (MMP) containing 20mM histidine, synthesis of histidase and urocanase was detected in crude extract at 3186±118 (U/mg-proteins) and 243±3 (10-3 U/mg-proteins), respectively. It was determined that the synthesis of these enzymes was induced by histidine because limited enzyme synthesis was observed in MMP containing 20mM of glutamate. In contrast, PAO4399, the spontaneous mutant of PAO1, can synthesize histidase and urocanase sufficiently under the nutrient conditions of MMP containing histidine or glutamate. A nucleotide sequence analysis of PAO4399 showed a C to G transition at nt 441 of the PA5105 gene, with this mutation causing an amino acid change of the tyrosine codon (TAC) Tyr 147 to stop codon (TAG). In the case of PAO4816, the knockout mutant strain of PAO1 with an inserted gentamicin (Gm)-cassette in the PA5105 gene, the cells grown in MMP containing 20mM of histidine or glutamate synthesized histidase and urocanase constitutively, in the same manner as PAO4399. The PA5105 gene product is highly homologous with the hutC gene product of Pseudomonas putida, which regulates histidase and urocanase gene expression. These findings support the role of the PA5105 gene of P.aeruginosa PAO1 as a repressor-type hutC gene that regulates histidase and urocanase synthesis under histidine-dependent nutrient conditions

The LKB1 Tumor Suppressor as a Biomarker in Mouse and Human Tissues

Germline mutations in the LKB1 gene (also known as STK11) cause the Peutz-Jeghers Syndrome, and somatic loss of LKB1 has emerged as causal event in a wide range of human malignancies, including melanoma, lung cancer, and cervical cancer. The LKB1 protein is a serine-threonine kinase that phosphorylates AMP-activated protein kinase (AMPK) and other downstream targets. Conditional knockout studies in mouse models have consistently shown that LKB1 loss promotes a highly-metastatic phenotype in diverse tissues, and human studies have demonstrated a strong association between LKB1 inactivation and tumor recurrence. Furthermore, LKB1 deficiency confers sensitivity to distinct classes of anticancer drugs. The ability to reliably identify LKB1-deficient tumors is thus likely to have important prognostic and predictive implications. Previous research studies have employed polyclonal antibodies with limited success, and there is no widely-employed immunohistochemical assay for LKB1. Here we report an assay based on a rabbit monoclonal antibody that can reliably detect endogenous LKB1 protein (and its absence) in mouse and human formalin-fixed, paraffin-embedded tissues. LKB1 protein levels determined through this assay correlated strongly with AMPK phosphorylation both in mouse and human tumors, and with mRNA levels in human tumors. Our studies fully validate this immunohistochemical assay for LKB1 in paraffin-embedded formalin tissue sections. This assay should be broadly useful for research studies employing mouse models and also for the development of human tissue-based assays for LKB1 in diverse clinical settings

Idiopathic Interstitial Pneumonia with Increased Serum Levels of Cancer-Associated Antigens, CA19-9 and SLX

We report a case of idiopathic interstitial pneumonia (IIP) with elevated serum levels of carbohydrate antigen 19-9 (CA19-9) and sialyl Lewisx-i (SLX). A 67-year-old Japanese woman was admitted to our hospital with a fever, dry cough and dyspnea on exertion. She had previously been admitted and had then been diagnosed as IIP. The serum level of SLX, measured by radioimmunoassay (RIA), was markedly elevated (120 U/mL; cut-off, < 38 U/mL). The serum level of CA19-9, measured by RIA, was at a slightly high level (46 U/mL; cut-off, < 40 U/mL). The values of CA19-9 and SLX were changed during her clinical course. These cancer-associated antigens were immunohistochemically expressed on the hyperplastic bronchiolar epithelium, on the surface epithelium cells of microscopic honeycombing and on exudates in air space. Repeated damage to the lungs may have forced these antigens of the markers into the blood circulation, which may have resulted in the elevated serum levels of CA19-9 and SLX observed in this patient

Testing the External Shock Model of Gamma-Ray Bursts using the Late-Time Simultaneous Optical and X-ray Afterglows

We study the ``normal'' decay phase of the X-ray afterglows of gamma-ray bursts (GRBs), which follows the shallow decay phase, using the events simultaneously observed in the R-band. The classical external shock model -- in which neither the delayed energy injection nor time-dependency of shock micro-physics is considered -- shows that the decay indices of the X-ray and R-band light curves, $\alpha_{\rm X}$ and $\alpha_{\rm O}$, obey a certain relation, and that in particular, $\alpha_{\rm O}-\alpha_{\rm X}$ should be larger than -1/4 unless the ambient density increases with the distance from the central engine. For our selected 14 samples, we have found that 4 events violate the limit at more than the 3$\sigma$ level, so that a fraction of events are outliers of the classical external shock model at the ``normal'' decay phase.Comment: Accepted for publication in ApJL. 12 page, 2 figures, 2 table

Prevalence and predictors of direct discharge home following hospitalization of patients with serious adverse events managed by the rapid response system in Japan: a multicenter, retrospective, observational study

Aim: The rapid response system (RRS) is an in-hospital medical safety system. To date, not much is known about patient disposition after RRS activation, especially discharge home. This study aimed to investigate the prevalence, characteristics, and outcomes of patients with adverse events who required RRS activation. Methods: Retrospective data from the In-Hospital Emergency Registry in Japan collected from April 2016 to November 2020 were eligible for our analysis. We divided patients into Home Discharge, Transfer, and Death groups. The primary outcome was the prevalence of direct discharge home, and independently associated factors were determined using multivariable logistic regression. Results: We enrolled 2,043 patients who met the inclusion criteria. The prevalence of discharge home was 45.7%; 934 patients were included in the Home Discharge group. Age (adjusted odds ratio [AOR] 0.96; 95% confidence interval [CI], 0.95-0.97), malignancy (AOR 0.69; 95% CI, 0.48-0.99), oxygen administration before RRS (AOR 0.49; 95% CI, 0.36-0.66), cerebral performance category score on admission (AOR 0.38; 95% CI, 0.26-0.56), do not attempt resuscitation order before RRS (AOR 0.17; 95% CI, 0.10-0.29), RRS call for respiratory failure (AOR 0.50; 95% CI, 0.34-0.72), RRS call for stroke (AOR 0.12; 95% CI, 0.03-0.37), and intubation (AOR 0.20; 95% CI, 0.12-0.34) were independently negative, and RRS call for anaphylaxis (AOR 15.3; 95% CI, 2.72-86.3) was positively associated with discharge home. Conclusion: Less than half of the in-hospital patients under RRS activation could discharge home. Patients' conditions before RRS activation, disorders requiring RRS activation, and intubation were factors that affected direct discharge home

Prevalence of twitching motility in Pseudomonas aeruginosa isolated from medical facilities -Prevalence of TM in P. aeruginosa isolated from medical facilities-

Pseudomonas aeruginosa is an opportunistic bacterial pathogen, the infection system of which includes the possession of type IV pili. Type IV pili-dependent twitching motility (TM) is important for attachment to the epithelium and biofilm formation. Accordingly, there is a close relationship between the expression of pili and infection through intermediate biofilm formation. However, not all isolated strains of P. aeruginosa carry the pili-motility function. In this study, we isolated P. aeruginosa strains from various medical facilities and determined the TM prevalence. A total of 27 strains were isolated from bathrooms and nursing station sinks, 52% of which possessed clear TM ability. The strength of the TM ability differed by strain, with 15% indicating a marked ability. These results support the possibility that some of P. aeruginosa strains isolated from medical facilities can act as causative organisms of infection

Characterization of Acinetobacter clinical isolates

Members of the genus Acinetobacter are typical opportunistic bacterial pathogens that can survive for a long term even on inanimate surfaces. Acinetobacter species have natural and acquired antibiotic resistance mechanisms that provide resistance against a broad range of antimicrobial agents. Between April 2010 and March 2011, 6 clinical Acinetobacter sp. strains were isolated from expectoration or aspiration sputum samples in a local medical treatment-type hospital in Osaka prefecture. The antibiotic susceptibility breakpoint test showed that all the 6 isolates were ciprofloxacin-resistant. Strain AHU-70, which was identified as A.baumannii by 16S rRNA sequencing and polymerase chain reaction detection of the blaOXA-51-like gene, showed high levels of resistance to ciprofloxacin by the minimum inhibitory concentration (MIC) test. Preliminary research in Japan, based on nationwide susceptibility surveillance of ciprofloxacin against A.baumannii isolates showed that approximately 90% of the isolates were ciprofloxacin-susceptible. Given these results, further strain level identification of isolates is required to determine whether resistance to ciprofloxacin is an overall trait of these bacteria in the sampled local area or is restricted to a specific strain within particular hospitals

Structural basis of Sec-independent membrane protein insertion by YidC

[プレスリリース]バイオサイエンス研究科膜分子複合機能学研究室の塚崎智也准教授らの研究グループが、タンパク質を細胞膜に組み込むメカニズムを解明しました（2014/04/17）Newly synthesized membrane proteins must be accurately inserted into the membrane, folded and assembled for proper functioning. The protein YidC inserts its substrates into the membrane, thereby facilitating membrane protein assembly in bacteria; the homologous proteins Oxa1 and Alb3 have the same function in mitochondria and chloroplasts, respectively1, 2. In the bacterial cytoplasmic membrane, YidC functions as an independent insertase and a membrane chaperone in cooperation with the translocon SecYEG3, 4, 5. Here we present the crystal structure of YidC from Bacillus halodurans, at 2.4 Å resolution. The structure reveals a novel fold, in which five conserved transmembrane helices form a positively charged hydrophilic groove that is open towards both the lipid bilayer and the cytoplasm but closed on the extracellular side. Structure-based in vivo analyses reveal that a conserved arginine residue in the groove is important for the insertion of membrane proteins by YidC. We propose an insertion mechanism for single-spanning membrane proteins, in which the hydrophilic environment generated by the groove recruits the extracellular regions of substrates into the low-dielectric environment of the membrane