Dual recognition of multiple signals in bacterial outer membrane proteins enhances assembly and maintains membrane integrity.

Outer membrane proteins (OMPs) are essential components of the outer membrane of Gram-negative bacteria. In terms of protein targeting and assembly, the current dogma holds that a 'ß-signal' imprinted in the final ß-strand of the OMP engages the ß-barrel assembly machinery (BAM) complex to initiate membrane insertion and assembly of the OMP into the outer membrane. Here, we revealed an additional rule that signals equivalent to the ß-signal are repeated in other, internal ß-strands within bacterial OMPs, by peptidomimetic and mutational analysis. The internal signal is needed to promote the efficiency of the assembly reaction of these OMPs. BamD, an essential subunit of the BAM complex, recognizes the internal signal and the ß-signal, arranging several ß-strands and partial folding for rapid OMP assembly. The internal signal-BamD ordering system is not essential for bacterial viability but is necessary to retain the integrity of the outer membrane against antibiotics and other environmental insults.

Symptomatic Liver Cyst Successfully Treated with Transgastric Drainage and Sclerotherapy Using Minocycline Hydrochloride.

A liver cyst is hepatic fluid-filled cavities often detected in clinical surveillances such as a health examination. Although the liver cyst is usually asymptomatic and observed without any therapeutic intervention, it can be symptomatic and needs treatment due to its enlargement, hemorrhage, and infection. A 74-year-old woman presented with upper abdominal pain and a huge liver cyst in the left lobe. Several examinations including image findings revealed that the symptom could be derived from the liver cyst. Although there is no definite guideline of treatment for symptomatic liver cysts, percutaneous ultrasound-guided drainage with sclerotherapy or surgery is often selected. Because of anatomical accessibility to the liver cyst and the patient's wish, we performed endoscopic transgastric drainage with insertion of both an internal stent and an external nasocystic tube. Sclerotherapy with minocycline hydrochloride was performed through the nasocystic tube, and the liver cyst shrunk completely without any complications. This is the first reported method of administering minocycline hydrochloride through a nasocystic tube, which can be a therapeutic option for patients with symptomatic liver cysts.

Low skeletal muscle mass and high visceral adiposity are associated with recurrence of acute cholecystitis after conservative management: A propensity score-matched cohort study.

BACKGROUND: Recurrent acute cholecystitis (RAC) can occur after non-surgical treatment for acute cholecystitis (AC), and can be more severe in comparison to the first episode of AC. Low skeletal muscle mass or adiposity have various effects in several diseases. We aimed to clarify the relationship between RAC and body parameters. METHODS: Patients with AC who were treated at our hospital between January 2011 and March 2022 were enrolled. The psoas muscle mass and adipose tissue area at the third lumbar level were measured using computed tomography at the first episode of AC. The areas were divided by height to obtain the psoas muscle mass index (PMI) and subcutaneous/visceral adipose tissue index (SATI/VATI). According to median VATI, SATI and PMI values by sex, patients were divided into the high and low PMI groups. We performed propensity score matching to eliminate the baseline differences between the high PMI and low PMI groups and analyzed the cumulative incidence and predictors of RAC. RESULTS: The entire cohort was divided into the high PMI (n = 81) and low PMI (n = 80) groups. In the propensity score-matched cohort there were 57 patients in each group. In Kaplan-Meier analysis, the low PMI group and the high VATI group had a significantly higher cumulative incidence of RAC than their counterparts (log-rank P = 0.001 and 0.015, respectively). In a multivariate Cox regression analysis, the hazard ratios of low PMI and low VATI for RAC were 5.250 (95% confidence interval 1.083-25.450, P = 0.039) and 0.158 (95% confidence interval: 0.026-0.937, P = 0.042), respectively. CONCLUSIONS: Low skeletal muscle mass and high visceral adiposity were independent risk factors for RAC.

Categorization of Escherichia coli outer membrane proteins by dependence on accessory proteins of the ß-barrel assembly machinery complex.

The outer membrane (OM) of gram-negative bacteria is populated by various outer membrane proteins (OMPs) that fold into a unique ß-barrel transmembrane domain. Most OMPs are assembled into the OM by the ß-barrel assembly machinery (BAM) complex. In Escherichia coli, the BAM complex is composed of two essential proteins (BamA and BamD) and three nonessential accessory proteins (BamB, BamC, and BamE). The currently proposed molecular mechanisms of the BAM complex involve only essential subunits, with the function of the accessory proteins remaining largely unknown. Here, we compared the accessory protein requirements for the assembly of seven different OMPs, 8- to 22-stranded, by our in vitro reconstitution assay using an E. coli mid-density membrane. BamE was responsible for the full efficiency of the assembly of all tested OMPs, as it enhanced the stability of essential subunit binding. BamB increased the assembly efficiency of more than 16-stranded OMPs, whereas BamC was not required for the assembly of any tested OMPs. Our categorization of the requirements of BAM complex accessory proteins in the assembly of substrate OMPs enables us to identify potential targets for the development of new antibiotics.

Experimental comparison of classification methods for key kinase identification for neurite elongation.

Kinases in a developing neuron play important roles in elongating a neurite with their complex interactions. To elucidate the effect of each kinase on neurite elongation and regeneration from a small set of experiments, we applied machine learning methods to synthetic datasets based on a biologically feasible model. The result showed the ridged partial least squares (RPLS) algorithm performed better than other standard algorithms such as naive Bayes classifier, support vector machines and random forest classification. This suggests the effectiveness of dimension reduction done in RPLS.