Basophil differentiation, heterogeneity, and functional implications.

Basophils, rare granulocytes, have long been acknowledged for their roles in type 2 immune responses. However, the mechanisms by which basophils adapt their functions to diverse mammalian microenvironments remain unclear. Recent advancements in specific research tools and single-cell-based technologies have greatly enhanced our understanding of basophils. Several studies have shown that basophils play a role in maintaining homeostasis but can also contribute to pathology in various tissues and organs, including skin, lung, and others. Here, we provide an overview of recent basophil research, including cell development, characteristics, and functions. Based on an increasing understanding of basophil biology, we suggest that the precise targeting of basophil features might be beneficial in alleviating certain pathologies such as asthma, atopic dermatitis (AD), and others.

Mechanistic analysis of carbon-carbon bond formation by deoxypodophyllotoxin synthase.

Deoxypodophyllotoxin contains a core of four fused rings (A to D) with three consecutive chiral centers, the last being created by the attachment of a peripheral trimethoxyphenyl ring (E) to ring C. Previous studies have suggested that the iron(II)- and 2-oxoglutarate-dependent (Fe/2OG) oxygenase, deoxypodophyllotoxin synthase (DPS), catalyzes the oxidative coupling of ring B and ring E to form ring C and complete the tetracyclic core. Despite recent efforts to deploy DPS in the preparation of deoxypodophyllotoxin analogs, the mechanism underlying the regio- and stereoselectivity of this cyclization event has not been elucidated. Herein, we report 1) two structures of DPS in complex with 2OG and (±)-yatein, 2) in vitro analysis of enzymatic reactivity with substrate analogs, and 3) model reactions addressing DPS's catalytic mechanism. The results disfavor a prior proposal of on-pathway benzylic hydroxylation. Rather, the DPS-catalyzed cyclization likely proceeds by hydrogen atom abstraction from C7', oxidation of the benzylic radical to a carbocation, Friedel-Crafts-like ring closure, and rearomatization of ring B by C6 deprotonation. This mechanism adds to the known pathways for transformation of the carbon-centered radical in Fe/2OG enzymes and suggests what types of substrate modification are likely tolerable in DPS-catalyzed production of deoxypodophyllotoxin analogs.

Prognostic significance of surgery and radiotherapy in elderly patients with localized prostate cancer: establishing and time-based external validation a nomogram from SEER-based study.

OBJECTIVE: Prostate cancer (PC) is a significant disease affecting men's health worldwide. More than 60% of patients over 65 years old and more than 80% are diagnosed with localized PC. The current choice of treatment modalities for localized PC and whether overtreatment is controversial. Therefore, we wanted to construct a nomogram to predict the risk factors associated with cancer-specific survival (CSS) and overall survival (OS) in elderly patients with localized PC while assessing the survival differences in surgery and radiotherapy for elderly patients with localized PC. METHODS: Data of patients with localized PC over 65 years were obtained from the Surveillance, Epidemiology, and End Results (SEER) database. Univariate and multivariate Cox regression models were used to determine independent risk factors for CSS and OS. Nomograms predicting CSS and OS were built using multivariate Cox regression models. The consistency index (C-index), the area under the subject operating characteristic curve (AUC), and the calibration curve were used to test the accuracy and discrimination of the prediction model. Decision curve analysis (DCA) was used to test the potential clinical value of this model. RESULTS: A total of 90,434 patients over 65 years and diagnosed with localized PC from 2010 to 2018 were included in the study. All patients were randomly assigned to the training set (n = 63,328) and the validation set (n = 27,106). Univariate and multivariate Cox regression model analysis showed that age, race, marriage, T stage, surgical, radiotherapy, prostate-specific antigen (PSA), and Gleason score (GS) were independent risk factors for predicting CSS in elderly patients with localized PC. Age, race, marriage, surgery, radiotherapy, PSA, and GS were independent risk factors for predicting OS in elderly patients with localized PC. The c-index of the training and validation sets for the predicted CSS is 0.802(95%CI:0.788-0.816) and 0.798(95%CI:0.776-0.820, respectively). The c-index of the training and validation sets for predicting OS is 0.712(95%:0.704-0.720) and 0.724(95%:0.714-0.734). It shows that the nomograms have excellent discriminatory ability. The AUC and the calibration curves also show good accuracy and discriminability. CONCLUSION: We have developed new nomograms to predict CSS and OS in elderly patients with localized PC. After internal validation and external temporal validation with reasonable accuracy, reliability and potential clinical value, the model can be used for clinically assisted decision-making.

Brain tissue heterotopic in the adrenal gland in a child: a scarce case report.

Heterotopic brain tissue is rare and has not been reported. Our center made the first report. 4 years and 2 months old Girl presented with a cystic mass in the right adrenal gland 2 weeks after right upper abdominal pain. The operation was successful, and the diagnosis was confirmed by postoperative pathology. 6 months after the procedure, the incision healed well without recurrence. This case report has a detailed diagnosis and treatment process and satisfactory examination results. It can provide a reference for diagnosing and treating clinical HBT and reduce the risk of misdiagnosis and mistreatment.

Structural Element of Vitamin U-Mimicking Antibacterial Polypeptide with Ultrahigh Selectivity for Effectively Treating MRSA Infections.

Antimicrobial peptides (AMPs) exhibit mighty antibacterial properties without inducing drug resistance. Achieving much higher selectivity of AMPs towards bacteria and normal cells has always been a continuous goal to be pursued. Herein, a series of sulfonium-based polypeptides with different degrees of branching and polymerization were synthesized by mimicking the structure of vitamin U. The polypeptide, G2 -PM-1H+ , shows both potent antibacterial activity and the highest selectivity index of 16000 among the reported AMPs or peptoids (e.g., the known index of 9600 for recorded peptoid in "Angew. Chem. Int. Ed., 2020, 59, 6412."), which can be attributed to the high positive charge density of sulfonium and the regulation of hydrophobic chains in the structure. The antibacterial mechanisms of G2 -PM-1H+ are primarily ascribed to the interaction with the membrane, production of reactive oxygen species (ROS), and disfunction of ribosomes. Meanwhile, altering the degree of alkylation leads to selective antibacteria against either gram-positive or gram-negative bacteria in a mixed-bacteria model. Additionally, both in vitro and in vivo experiments demonstrated that G2 -PM-1H+ exhibited superior efficacy against methicillin-resistant Staphylococcus aureus (MRSA) compared to vancomycin. Together, these results show that G2 -PM-1H+ possesses high biocompatibility and is a potential pharmaceutical candidate in combating bacteria significantly threatening human health.

A Ferric-Superoxide Intermediate Initiates P450-Catalyzed Cyclic Dipeptide Dimerization.

The cytochrome P450 (CYP) AspB is involved in the biosynthesis of the diketopiperazine (DKP) aspergilazine A. Tryptophan-linked dimeric DKP alkaloids are a large family of natural products that are found in numerous species and exhibit broad and often potent bioactivity. The proposed mechanisms for C-N bond formation by AspB, and similar C-C bond formations by related CYPs, have invoked the use of a ferryl-intermediate as an oxidant to promote substrate dimerization. Here, the parallel application of steady-state and transient kinetic approaches reveals a very different mechanism that involves a ferric-superoxide species as a primary oxidant to initiate DKP-assembly. Single turnover kinetic isotope effects and a substrate analog suggest the probable nature and site for abstraction. The direct observation of CYP-superoxide reactivity rationalizes the atypical outcome of AspB and reveals a new reaction manifold in heme enzymes.

A fetal fraction enrichment method reduces false negatives and increases test success rate of fetal chromosome aneuploidy detection in early pregnancy loss.

OBJECTIVE: We and others have previously demonstrated that the size-selection enrichment method could remarkably improve fetal fraction (FF) in the early gestational age (GA, 12-13 weeks), suggesting that 9 or 10 weeks should not be used as a threshold for GA in size-selection noninvasive prenatal screening (NIPS). Here, we assessed whether this method was reliable for detecting fetal chromosomal aneuploidy at the earliest GA (6-8 weeks). METHODS: Size-selection NIPS for fetal chromosomal aneuploidy was applied to 208 pregnancy plasma samples (102 male and 106 female fetuses), while the 169 pregnancy samples with male fetuses also underwent standard NIPS. Multivariable linear regression models were used to evaluate the association between fold-change of FF and experimental factors. RESULTS: The sensitivity of the cell-free DNA (cfDNA) test in detecting aneuploidy was 100% when screened with FF enrichment, whereas the sensitivity of the same patients was only 62.5% (5/8) without FF enrichment. In the 102 pregnancy samples with male fetuses, FF increased from 6.1% to 15.7%, and the median increase in FF was 2.8-fold with enrichment. Moreover, there was a trend toward an increasing success rate of the cfDNA test from 6 to 13 weeks of gestation, especially when the test success rate reached 100% after 7 weeks with FF enrichment. Multivariate linear regression analysis demonstrated that a lower initial FF, shorter cfDNA size, increased body mass index (BMI), and later GA were all independent predictors of a higher fold-change of FF. Compared with ≤ 120 bp cfDNA fragments, the mean fold-change of FF differences was 0.820 for 121-125 bp, 0.229 for 126-130 bp, - 0.154 for 131-135 bp, - 0.525 for 136-140 bp and - 0.934 for > 140 bp (Ptrend < 0.0001), suggesting that fold-change of FF significantly decreased with cfDNA fragments > 125 bp. These results were statistically significant after adjusting for confounding factors in the models for fold-change of FF. CONCLUSIONS: The FF enrichment method is a reasonable strategy to detect fetal chromosomal aneuploidy in early pregnancy loss with reduced false negatives and increased test success rate after 7 weeks of GA and should be recommended for patients with early pregnancy loss.

Clinical and prognostic analysis of 42 children with malignant rhabdoid tumor of the kidney: a 7-year retrospective multi-center study.

OBJECTIVE: To discuss the clinical and prognostic indicators of pediatric malignant rhabdoid tumor of the kidney (MRTK), and to increase the understanding of the occurrence and development of MRTK. METHODS: From July 2014 to September 2021, all cases were confirmed by postoperative pathological examination. Among the 42 patients, there were 25 males and 17 females, with a median age of 10 (1-84) months. Abdominal mass or hematuria were the main clinical manifestations. Preoperative chemotherapy was performed in 9 cases (VC). The tumor stages were stage I-IV. Preoperative metastasis was found in 9 cases; the most common site was the lung. Postoperative patients received conventional chemotherapy, including VDACE regimen and UH-1 regimen. Among the 42 children in this group, survival at follow-up in this study was 26.2%(11/42). RESULTS: Preoperative anemia was found by univariate analysis, hypertension and hypercalcemia had shorter survival time. In addition, tumor-related factors had a significant impact on survival, with incomplete tumor resection, lymph node metastasis, stage III-IV had a lower survival rate. The impact of postoperative factors on survival included postoperative complications had a lower survival rate. The children were younger than 12 months, preoperative metastasis, no chemotherapy was performed after surgery was an independent risk factor for the prognosis of MRTK. CONCLUSION: The main clinical manifestations about MRTK were abdominal mass and hematuria. Preoperative chemotherapy did not significantly improve the prognosis. Postoperative chemotherapy can significantly improve the survival rate. Diagnosis depends on clinical manifestations, imaging, histopathology, immunohistochemistry and other comprehensive judgment. Age less than 12 months, preoperative metastasis, and no postoperative chemotherapy were independent risk factors for prognosis.

Biosynthesis of a New Fusaoctaxin Virulence Factor in Fusarium graminearum Relies on a Distinct Path To Form a Guanidinoacetyl Starter Unit Priming Nonribosomal Octapeptidyl Assembly.

Fusarium graminearum is a pathogenic fungus causing huge economic losses worldwide via crop infection leading to yield reduction and grain contamination. The process through which the fungal invasion occurs remains poorly understood. We recently characterized fusaoctaxin A in F. graminearum, where this octapeptide virulence factor results from an assembly line encoded in fg3_54, a gene cluster proved to be involved in fungal pathogenicity and host adaptation. Focusing on genes in this cluster that are related to fungal invasiveness but not to the biosynthesis of fusaoctaxin A, we here report the identification and characterization of fusaoctaxin B, a new octapeptide virulence factor with comparable activity in wheat infection. Fusaoctaxin B differs from fusaoctaxin A at the N-terminus by possessing a guanidinoacetic acid (GAA) unit, formation of which depends on the combined activities of the protein products of fgm1-3. Fgm1 is a cytochrome P450 protein that oxygenates l-Arg to 4(R)-hydroxyl-l-Arg in a regio- and stereoselective manner. Then, Cß-Cγ bond cleavage proceeds in the presence of Fgm3, a pyridoxal-5'-phosphate-dependent lyase, giving guanidinoacetaldehyde and l-Ala. Rather than being directly oxidized to GAA, the guanidine-containing aldehyde undergoes spontaneous cyclization and subsequent enzymatic dehydrogenation to provide glycociamidine, which is linearized by Fgm2, a metallo-dependent amidohydrolase. The GAA path in F. graminearum is distinct from that previously known to involve l-Arg:l-Gly aminidotransferase activity. To provide this nonproteinogenic starter unit that primes nonribosomal octapeptidyl assembly, F. graminearum employs new chemistry to process l-Arg through inert C-H bond activation, selective C-C bond cleavage, cyclization-based alcohol dehydrogenation, and amidohydrolysis-associated linearization.

BesC Initiates C-C Cleavage through a Substrate-Triggered and Reactive Diferric-Peroxo Intermediate.

BesC catalyzes the iron- and O2-dependent cleavage of 4-chloro-l-lysine to form 4-chloro-l-allylglycine, formaldehyde, and ammonia. This process is a critical step for a biosynthetic pathway that generates a terminal alkyne amino acid which can be leveraged as a useful bio-orthogonal handle for protein labeling. As a member of an emerging family of diiron enzymes that are typified by their heme oxygenase-like fold and a very similar set of coordinating ligands, recently termed HDOs, BesC performs an unusual type of carbon-carbon cleavage reaction that is a significant departure from reactions catalyzed by canonical dinuclear-iron enzymes. Here, we show that BesC activates O2 in a substrate-gated manner to generate a diferric-peroxo intermediate. Examination of the reactivity of the peroxo intermediate with a series of lysine derivatives demonstrates that BesC initiates this unique reaction trajectory via cleavage of the C4-H bond; this process represents the rate-limiting step in a single turnover reaction. The observed reactivity of BesC represents the first example of a dinuclear-iron enzyme that utilizes a diferric-peroxo intermediate to capably cleave a C-H bond as part of its native function, thus circumventing the formation of a high-valent intermediate more commonly associated with substrate monooxygenations.

Transition of Conformation and Solubility in ß-Sheet-Structured Poly(l-cysteine)s with Methylthio or Sulfonium Pendants.

Poly(l-cysteine)s with methylthio pendants (PMTLCs) were synthesized by ring-opening polymerization of a new l-cysteine-based N-carboxyanhydride. The thioether bonds of PMTLC can be readily oxidized by H2O2 yielding water-soluble PMTLCOX. The methylthio groups can undergo an alkylation reaction using methyl iodide and a subsequent ion-exchange reaction yielding sulfonium-based polypeptides (PPLC-DMS-X, where X = I, BF4). PPLC-DMS-X showed upper critical solution temperature-type thermo- and oxidation-responsive properties in aqueous solutions. Both PMTLC and PPLC-DMS-X showed oxidation-induced ß-sheet to α-helix transitions. The absorbance of PPLC-DMS-I and methyl orange aqueous solution displayed a significant linear correlation with temperature, which makes the sulfonium-based polypeptides good candidates in the field of temperature sensors.

Single-Chain Nanoparticle-Based Coatings with Improved Bactericidal Activity and Antifouling Properties.

Dual-function antibacterial surfaces have exhibited promising potential in addressing implant-associated infections. However, both bactericidal and antifouling properties need to be further improved prior to practical uses. Herein, we report the preparation and properties of a linear block copolymer coating (LP-KF) and a single-chain nanoparticle coating (NP-KF) with poly(ethylene glycol) (PEG) and cationic polypeptide segments. NP-KF with cyclic PEG segments and densely charged polypeptide segments was expected to display improved bactericidal and antifouling properties. LP-KF was prepared by the combination of ring-opening polymerization of N-carboxyanhydride (NCA) monomers and subsequent deprotection. NP-KF was prepared by intramolecular cross-linking of LP-KF in diluted solutions. Both LP-KF- and NP-KF-coated PDMS surfaces were prepared by dipping with polydopamine-coated surfaces. They showed superior in vitro bactericidal activity against both Staphylococcus aureus and Escherichia coli with >99.9% killing efficacy, excellent protein adsorption resistance, antibacterial adhesion, and low cytotoxicity. The NP-KF coating showed higher bactericidal activity and antifouling properties than its linear counterpart. It also showed significant anti-infective property and histocompatibility in vivo, which makes it a good candidate for implants and biomedical device applications.

Facile Synthesis of Imidazolium-Based Block Copolypeptides with Excellent Antimicrobial Activity.

Antimicrobial polypeptides are promising mimics of antimicrobial peptides (AMPs) with low risks of antimicrobial resistance (AMR). Polypeptides with facile and efficient production, high antimicrobial activity, and low toxicity toward mammalian cells are highly desirable for practical applications. Herein, triblock copolypeptides with chloro groups (PPGn-PCPBLGm) and different main-chain lengths were synthesized via an ultrafast ring-opening polymerization (ROP) using a macroinitiator, namely poly(propylene glycol) bis(2-aminopropyl ether), and purified or nonpurified monomer (i.e., CPBLG-NCA). PPGn-PCPBLGm with 90 amino acid residues can be readily prepared within 300 s. Imidazolium-based block copolypeptides (PPGn-PILm) were facilely prepared via nucleophilic substitution of PPGn-PCPBLGm with NaN3 and subsequent "click" chemistry. α-Helical PPGn-PILm can self-assemble into nanostructured and cationic micelles which displayed highly potent antimicrobial activity and low hemolysis. The top-performing material, namely PPG34-PIL70, showed low minimum inhibitory concentration (MIC) against both Gram-positive S. aureus and Gram-negative E. coli (25 µg mL-1). It also displayed low toxicity against mouse embryonic fibroblast (NIH 3T3) and human embryonic kidney (293T) cells at 2× MIC.

Bone marrow-derived mesenchymal stem cell-derived exosomal microRNA-208a promotes osteosarcoma cell proliferation, migration, and invasion.

A recent study has discovered that mesenchymal stem cells (MSCs) are recruited into tumors and MSC-derived exosomes in a novel mechanism of cell-to-cell communication in human cancers. Here, in this study, we explore the impact of the microRNA-208a (miR-208a)-enriched exosomes derived from bone marrow-derived mesenchymal stem cells (BMSCs) on osteosarcoma cells. Human osteosarcoma cells MG-63 and Saos-2 were exposed to BMSCs-derived exosomes treated with either miR-208a mimic or inhibitor. The MTT assay, transwell migration assay, and soft agar colony formation assay were used to evaluate the viability, migration, and clonogenicity of osteosarcoma cells. Bioinformatics analysis and dual-luciferase reporter gene assays validated the targeted relationship between miR-208a and PDCD4. Western blot assay was used to detect the expression of PDCD4 and related proteins in the ERK1/2 pathway in osteosarcoma cells. BMSCs communicated with osteosarcoma cells via exosomes. Ectopic expression of miR-208a was shown to increase the viability, migration, and clonogenicity of osteosarcoma cells. Analysis of the exosomal content identified miR-208a as a mediator of the exosomal effects on osteosarcoma cells in part via downregulation of PDCD4 and activating the ERK1/2 pathway. In summary, our study illuminates that BMSC-derived exosomal miR-208a enhances the progression of osteosarcoma.

Synthesis and Properties of Mono- or Diamine-Initiated Imidazolium-Based Cationic Polypeptides.

A series of cationic polypeptide imidazolium conjugates were prepared by ring-opening polymerization (ROP) of γ-4-(3-chloropropoxycarbonyl)benzyl-L- glutamic acid-based N-carboxyanhydride (CPBLG-NCA) initiated by various mono- or diamine initiators and subsequent side-chain modification with high grafting efficiency. Rapid and controlled ROP was achieved by polymerizing CPBLG-NCA in a dichloromethane/NaHCO3/H2O solvent mixture with the amine initiators. The resulting polypeptides bearing imidazolium iodide pendants showed reversible upper critical solution temperature (UCST)-type thermoresponsive properties in both ethanol and DI water while the polypeptides with tetrafluoroborate counter-anions showed a UCST in phosphate buffer saline (PBS). The cloud point temperature (Tcp) in ethanol and aqueous solutions can be tuned by both molecular weight and the end- or linkage-groups in the main chain. The cationic polypeptides showed good antibacterial activity against Staphylococcus aureus and low hemolysis. Our results provide a facile and rapid ROP strategy to develop new families of stimuli-responsive polypeptides with tunable properties as well as antibacterial polypeptides with optimized selectivity.

Validation of PM2.5 model particle through physicochemical evaluation and atherosclerotic plaque formation in ApoE-/- mice.

PM2.5 particles are regarded as prominent risk factors that contribute to the development of atherosclerosis. However, the composition of PM2.5 is rather complicated. This study aimed to provide a model particle that simulates the behavior of actual PM2.5, for subsequent use in exploring mechanisms and major complications arising from PM2.5. To establish model particles of PM2.5, a series of monodisperse SiO2 microspheres with different average grain diameters were mixed according to the size distribution of actual PM2.5. The organic carbon (OC) was removed from PM2.5 and coated onto the SiO2 model particle, to formulate simulant PM2.5. Results showed that the size distribution of the model particle was highly approximate to that of the PM2.5 core. The polycyclic aromatic hydrocarbon (PAHs) composition profile of the simulated PM2.5 were approximate to PM2.5, and loading efficiency was approximately 80%-120%. Furthermore, compared to the control, SiO2-only model particle had negligible cytotoxicity on cell viability and oxidative stress of HUVECs, and marginal effect on the lipid metabolism and atherosclerotic plaque formation in ApoE-/- mice. In contrast, simulated PM2.5 exhibited similar cytotoxic and detrimental effects on lipid metabolism and atherosclerotic plaque formation with actual PM2.5. Traffic-related PM2.5 had negative effects on endothelial function and led to the formation of atherosclerosis via oxidative stress. The simulated PM2.5 simulated the outcomes of actual PM2.5 exposure. Here, we show that SiO2 particle model cores coated with OC could significantly assist in the evaluation of the effects of specific organic compositions bound on PM2.5, specifically in the context of environmental health and safety.

Fine Tuning of Core-Shell Structure of Hyaluronic Acid/Cell-Penetrating Peptides/siRNA Nanoparticles for Enhanced Gene Delivery to Macrophages in Antiatherosclerotic Therapy.

Hyaluronic-acid (HA)-coated LOX-1-specific siRNA-condensed cell-penetrating peptide (CPP) nanocomplexes (NCs) were developed for targeted gene delivery to macrophages and suppression of lipid accumulation. The HA coating facilitated the accumulation of nanoparticles at leaky endothelium overexpressing CD44 receptors and was further degraded by hyaluronidase (HAase) intraplaques for exposing the naked CPP NCs and achieving the ultimate location into macrophages. The surface coating of HA was verified by the increased particle size, inverted zeta potential, and TEM images. The targeting mechanism was studied on the established injured endothelium-macrophage coculture system, which revealed that modification of higher molecular weight HA and higher HA coating density on NCs, termed as NPs-3, improved the intracellular uptake of nanoparticles by macrophages. Macrophages internalized NCs via caveolae-mediated endocytosis pathway. Moreover, NPs-3 exhibited better cellular drug efficacy in preventing macrophage-derived foam cell formation than other preparations. Compared with NCs, HA decoration showed enhanced atherosclerotic-lesion-targeting efficiency, proven by results from ex vivo imaging. Furthermore, atheroprotective efficacy study in apoE-deficient mice showed that NPs-3 had the best potent efficacy, which was demonstrated by the fewest atherosclerotic lesions sizes and lipid accumulation, the lowest macrophage infiltration, and the lowest expression of monocyte chemoattractant protein-1 (MCP-1), respectively. Collectively, the HA-coated CPP NCs were promising nanocarriers for efficient macrophage-targeted gene delivery and antiatherogenic therapy.

Actomyosin contractility drives bile regurgitation as an early response during obstructive cholestasis.

BACKGROUND & AIMS: A wide range of liver diseases manifest as biliary obstruction, or cholestasis. However, the sequence of molecular events triggered as part of the early hepatocellular homeostatic response in obstructive cholestasis is poorly elucidated. Pericanalicular actin is known to accumulate during obstructive cholestasis. Therefore, we hypothesized that the pericanalicular actin cortex undergoes significant remodeling as a regulatory response to obstructive cholestasis. METHODS: In vivo investigations were performed in a bile duct-ligated mouse model. Actomyosin contractility was assessed using sandwich-cultured rat hepatocytes transfected with various fluorescently labeled proteins and pharmacological inhibitors of actomyosin contractility. RESULTS: Actomyosin contractility induces transient deformations along the canalicular membrane, a process we have termed inward blebbing. We show that these membrane intrusions are initiated by local ruptures in the pericanalicular actin cortex; and they typically retract following repair by actin polymerization and actomyosin contraction. However, above a certain osmotic pressure threshold, these inward blebs pinch away from the canalicular membrane into the hepatocyte cytoplasm as large vesicles (2-8µm). Importantly, we show that these vesicles aid in the regurgitation of bile from the bile canaliculi. CONCLUSION: Actomyosin contractility induces the formation of bile-regurgitative vesicles, thus serving as an early homeostatic mechanism against increased biliary pressure during cholestasis. LAY SUMMARY: Bile canaliculi expand and contract in response to the amount of secreted bile, and resistance from the surrounding actin bundles. Further expansion due to bile duct blockade leads to the formation of inward blebs, which carry away excess bile to prevent bile build up in the canaliculi.

Natural product driven diversity via skeletal remodeling of caryophyllene ß-lactam.

(-)-ß-Caryophyllene was decorated with a privileged ß-lactam motif and subsequently converted into highly diverse scaffolds via remodeling of the ring system. The structures were defined by spectroscopic data, X-ray diffraction analysis, and experimental and calculated ECD data. Compound 19 displayed the most potent activity against the rice blast fungus, while 6 had a more potent α-glucosidase inhibition than the drug acarbose. These findings demonstrate a concise protocol to exploit natural product-driven diversity.

Polypeptide vesicles with densely packed multilayer membranes.

Multilamellar membranes are important building blocks for constructing self-assembled structures with improved barrier properties, such as multilamellar lipid vesicles. Polymeric vesicles (polymersomes) have attracted growing interest, but multilamellar polymersomes are much less explored. Here, we report the formation of polypeptide vesicles with unprecedented densely packed multilayer membrane structures with poly(ethylene glycol)-block-poly(γ-(4,5-dimethoxy-2-nitrobenzyl)-l-glutamate) (PEG-b-PL), an amphiphilic diblock rod-coil copolymer containing a short PEG block and a short hydrophobic rod-like polypeptide segment. The polypeptide rods undergo smectic ordering with PEG buried between the hydrophobic polypeptide layers. The size of both blocks and the rigidity of the hydrophobic polypeptide block are critical in determining the membrane structures. Increase of the PEG length in PEG-b-PL results in the formation of bilayer sheets, while using random-coil polypeptide block leads to the formation of large compound micelles. UV treatment causes ester bond cleavage of the polypeptide side chain, which induces helix-to-coil transition, change of copolymer amphiphilicity, and eventual disassembly of vesicles. These polypeptide vesicles with unique membrane structures provide a new insight into self-assembly structure control by precisely tuning the composition and conformation of polymeric amphiphiles.