Vascularized tissue on mesh-assisted platform (VT-MAP): a novel approach for diverse organoid size culture and tailored cancer drug response analysis

This study presents the vascularized tissue on mesh-assisted platform (VT-MAP), a novel microfluidic in vitro model that uses an open microfluidic principle for cultivating vascularized organoids. Addressing the gap in 3D high-throughput platforms for drug response analysis, the VT-MAP can host tumor clusters of various sizes, allowing for precise, size-dependent drug interaction assessments. Key features include capability for forming versatile co-culture conditions (EC, fibroblasts and colon cancer organoids) that enhance tumor organoid viability and a perfusable vessel network that ensures efficient drug delivery and maintenance of organoid health. The VT-MAP enables the culture and analysis of organoids across a diverse size spectrum, from tens of microns to several millimeters. The VT-MAP addresses the inconsistencies in traditional organoid testing related to organoid size, which significantly impacts drug response and viability. Its ability to handle various organoid sizes leads to results that more accurately reflect patient-derived xenograft (PDX) models and differ markedly from traditional in vitro well plate-based methods. We introduce a novel image analysis algorithm that allows for quantitative analysis of organoid size-dependent drug responses, marking a significant step forward in replicating PDX models. The PDX sample from a positive responder exhibited a significant reduction in cell viability across all organoid sizes when exposed to chemotherapeutic agents (5-FU, oxaliplatin, and irinotecan), as expected for cytotoxic drugs. In sharp contrast, PDX samples of a negative responder showed little to no change in viability in smaller clusters and only a slight reduction in larger clusters. This differential response, accurately replicated in the VT-MAP, underscores its ability to generate data that align with PDX models and in vivo findings. Its capacity to handle various organoid sizes leads to results that more accurately reflect PDX models and differ markedly from traditional in vitro methods. The platform's distinct advantage lies in demonstrating how organoid size can critically influence drug response, revealing insights into cancer biology previously unattainable with conventional techniques.

Engineering choroid plexus-on-a-chip with oscillatory flow for modeling brain metastasis

The human brain choroid plexus (ChP) is a highly organized secretory tissue with a complex vascular system and epithelial layers in the ventricles of the brain. The ChP is the body's principal source of cerebrospinal fluid (CSF); it also functions as a barrier to separate the blood from CSF, because the movement of CSF through the body is pulsatile in nature. Thus far, it has been challenging to recreate the specialized features and dynamics of the ChP in a physiologically relevant microenvironment. In this study, we recapitulated the ChP structure by developing a microfluidic chip in accordance with established design rules. Furthermore, we used image processing and analysis to mimic CSF flow dynamics within a rlcking system; we also used a hydrogel containing laminin to mimic brain extracellular matrix (ECM). Human ChP cells were cultured in the ChP-on-a-chip with in vivo-like CSF dynamic flow and an engineered ECM. The key ChP characteristics of capillaries, the epithelial layer, and secreted components were recreated in the adjusted microenvironment of our human ChP-on-a-chip. The drug screening capabilities of the device were observed through physiologically relevant drug responses from breast cancer cells that had spread in the ChP. ChP immune responses were also recapitulated in this device, as demonstrated by the motility and cytotoxic effects of macrophages, which are the most prevalent immune cells in the ChP. Our human ChP-on-a-chip will facilitate the elucidation of ChP pathophysiology and support the development of therapeutics to treat cancers that have metastasized into the ChP.

U-IMPACT: a universal 3D microfluidic cell culture platform

The development of organs-on-a-chip has resulted in advances in the reconstruction of 3D cellular microenvironments. However, there remain limitations regarding applicability and manufacturability. Here, we present an injection-molded plastic array 3D universal culture platform (U-IMPACT) for various biological applications in a single platform, such as cocultures of various cell types, and spheroids (e.g., tumor spheroids, neurospheres) and tissues (e.g., microvessels). The U-IMPACT consists of three channels and a spheroid zone with a 96-well plate form factor. Specifically, organoids or spheroids (~500 μm) can be located in designated areas, while cell suspensions or cell-laden hydrogels can be selectively placed in three channels. For stable multichannel patterning, we developed a new patterning method based on capillary action, utilizing capillary channels and the native contact angle of the materials without any modification. We derived the optimal material hydrophilicity (contact angle of the body, 45-90°; substrate, <30°) for robust patterning through experiments and theoretical calculations. We demonstrated that the U-IMPACT can implement 3D tumor microenvironments for angiogenesis, vascularization, and tumor cell migration. Furthermore, we cultured neurospheres from induced neural stem cells. The U-IMPACT can serve as a multifunctional organ-on-a-chip platform for high-content and high-throughput screening.

Ethmoidal and maxillary nerve block versus systemic opioid administration during rhinoscopy in dogs: a non-randomised clinical trial

OBJECTIVES

This study aimed to evaluate the clinical effects of ethmoidal and maxillary nerve blocks during rhinoscopy in dogs.

MATERIALS AND METHODS

Fourteen dogs underwent rhinoscopy. Under general anaesthesia with isoflurane, ethmoidal and maxillary nerve blocks were applied bilaterally using 2% lidocaine before rhinoscopy in eight dogs (EM group). Six dogs were premedicated with hydromorphone (0.05 mg/kg) as a substitute for local nerve block (H group). During rhinoscopy, the heart rate, arterial blood pressure and end-tidal isoflurane concentration were recorded. The vaporizer setting was adjusted to increase the end-tidal isoflurane concentration when reflex movement was caused by nasal stimulation.

RESULTS

The H group, compared to the EM group, had an increase in HR that was 18 beats/minute (95% CI: 11 to 26) higher, an increase in SAP that was 22 mmHg (12 to 31) higher, an increase in MAP that was 15 mmHg (7 to 23) higher, an increase in DAP that was 12 mmHg (5 to 19) higher, and an increase in end-tidal isoflurane concentration that was 0.4% (0.3 to 0.5) higher. Head movement due to endoscope insertion was observed in 5/6 dogs (83.3%) in the H group and 1/8 dogs (12.5%) in the EM group (odds ratio, 0.029; ra95% CI, 0.001-0.574).

CLINICAL SIGNIFICANCE

Compared with administration of 0.05 mg/kg hydromorphone, concurrent block of the ethmoidal and maxillary nerves can reduce the cardiovascular response, reflex movement and anaesthetic requirement during rhinoscopy in dogs.

AB0339 EFFICACY, PHARMACOKINETICS AND SAFETY BETWEEN CT-P13 AND CHINA-APPROVED INFLIXIMAB: 54 WEEK RESULT FROM A PHASE III RANDOMIZED CONTROLLED TRIAL IN CHINESE PATIENTS WITH ACTIVE RHEUMATOID ARTHRITIS

Background

CT-P13 is an approved biosimilar to EU-approved and US-licensed Infliximab (INX) for the indications of rheumatoid arthritis (RA), adult and paediatric Crohn’s disease, adult and paediatric ulcerative colitis, ankylosing spondylitis, psoriatic arthritis and psoriasis.

Objectives

The purpose of this study was to demonstrate equivalence of efficacy and compare PK and safety profiles of CT-P13 and China-approved INX.

Methods

In this randomized, double blinded, multicenter, parallel-group, phase III study, patients with active RA who had been responding inadequately to methotrexate for at least 3 months, were randomized to receive either CT-P13 or China-approved INX. Patients were treated with doses of 3 mg/kg at Weeks 0, 2, 6, then every 8 weeks up to Week 54. Prior to dosing at Week 30, patients randomized to China-approved INX underwent a second randomization either to continue China-approved INX or to switch to CT-P13 at Week 30. Results of patients who underwent transition to CT-P13 were included in the China-approved INX group. The primary efficacy endpoint was change in DAS28 (CRP) from baseline to Week 14, which was analyzed using an analysis of covariance. Equivalence was determined if the 90% CI for the estimate of treatment difference was entirely contained within the predefined equivalence margin of -0.6 to 0.6.

Results

270 patients were randomly assigned to 2 treatment groups in a 1:1 ratio (136 and 134 patients in the CT-P13 and China-approved INX groups, respectively) and 184 patients completed the study. The least square mean change (standard error) of DAS28 (CRP) from baseline to Week 14, -1.566 [0.1419] and -1.547 [0.1491], was similar between the CT-P13 and China-approved INX groups, respectively. The 90% CI for the estimate of treatment difference (-0.29, 0.25) was contained within the predefined equivalence margin, which demonstrated therapeutic equivalence between the groups. The mean actual values for DAS28 (CRP) decreased from baseline to Week 54 and were similar between the groups (Figure 1). Additional efficacy endpoints, including ACR responses (ACR20 at Week 14; 60.6%, 54.8% and at Week 54; 65.1%, 60.6% in the CT-P13 and China-approved INX groups, respectively), EULAR responses, CDAI, and SDAI, were similar between the groups, even after switching at Week 30. During the study, mean serum INX concentrations were similar between the groups. Between Weeks 14 and 22, mean (percent coefficient of variation) AUCτ were 11156333.615 (44.796) ng·h/mL and 11462884.280 (51.057) ng·h/mL, and Cmax,ss were 66577.2 (31.4) ng/mL and 66356.1 (21.0) ng/mL in the CT-P13 and China-approved INX groups, respectively, which were similar between the groups. Most treatment-emergent AEs were grade 1 or 2 in intensity. One malignancy was reported in the CT-P13 group and no deaths were reported. The proportions of patients with anti-drug antibodies were similar between the groups, even after switching at Week 30. The overall safety profile of CT-P13 was comparable to that of China-approved INX and no new safety issues were observed (Table 1).

Table 1.

Summary of Safety Results

Number of patients (%)CT-P13 (N=136)China-approved Infliximab (N=133)Treatment-emergent AEsTotal115 (84.6%)107 (80.5%)Related97 (71.3%)86 (64.7%)Treatment-emergent serious AEsTotal17 (12.5%)12 (9.0%)Related10 (7.4%)6 (4.5%)Infusion related reaction/ hypersensitivity/anaphylactic reactionsTotal(=Related)20 (14.7%)19 (14.3%)InfectionsTotal45 (33.1%)43 (32.3%)Related36 (26.5%)40 (30.1%)

Note: Summary is presented for the safety population who received at least 1 dose (full or partial) of study drug.

Conclusion

The study demonstrated that efficacy of CT-P13 is equivalent to that of China-approved INX. Also, the PK and safety profiles of CT-P13 were comparable to those of China-approved INX. No loss of efficacy or difference in safety or immunogenicity was observed after switching from China-approved INX to CT-P13 at Week 30.

Disclosure of Interests

Jonathan Kay Consultant of: Boehringer Ingelheim GmbH; Pfizer Inc.; Samsung Bioepis; Sandoz Inc., Grant/research support from: Pfizer Inc. (paid to UMass Chan Medical School), Xiaofeng Zeng Grant/research support from: Celltrion, Inc, Lin Chen Grant/research support from: Celltrion, Inc, Kaijiang Tang Grant/research support from: Celltrion, Inc, guixiu shi Grant/research support from: Celltrion, Inc, Lin Liu Grant/research support from: Celltrion, Inc, Lijun Wu Grant/research support from: Celltrion, Inc, Yi Liu Grant/research support from: Celltrion, Inc, Jiankang Hu Grant/research support from: Celltrion, Inc, Shengyun Liu Grant/research support from: Celltrion, Inc, Zheng Yi Grant/research support from: Celltrion, Inc, Sung Hyun Kim Employee of: Celltrion, Inc, YunJu Bae Employee of: Celltrion, Inc, JeeHye Suh Employee of: Celltrion, Inc, Seungjin Rhee Employee of: Celltrion, Inc, SeulGi Lee Employee of: Celltrion, Inc, Chankyoung Hwang Employee of: Celltrion, Inc

Orientation and Mechanical Properties of Extrusion Cast PA 12 Films in Biaxial Stretching Process

The levels in biaxial orientations and mechanical properties of stretched extrusion cast polyamide 12 films were investigated with birefringence, wide angle X-ray diffraction (WAXD) pole figure and mechanical testing. Introduction of a pseudo-orthogonal crystalline symmetry enabled the calculation of White-Spruiell biaxial orientation factors using WAXD pole figure data. The orientation was uniaxial or biaxial depending on the stretch ratios along two principal stretching directions that are the machine direction (MD) and the transverse direction (TD). According to the WAXD pole figure patterns, planar alignments of hydrogen bonded layers were formed with respect to the film surface from most of the stretched films. Balanced stretching at higher stretch ratios enhanced the planarity. It was found that the mechanical properties (tensile strength and elongation at break) of the films had a close correlation with the out-of-plane birefringences.

Society of pediatric liver transplantation: Current registry status 2011-2018

BACKGROUND

SPLIT was founded in 1995 in order to collect comprehensive prospective data on pediatric liver transplantation, including waiting list data, transplant, and early and late outcomes. Since 2011, data collection of the current registry has been refined to focus on prospective data and outcomes only after transplant to serve as a foundation for the future development of targeted clinical studies.

OBJECTIVE

To report the outcomes of the SPLIT registry from 2011 to 2018.

METHODS

This is a multicenter, cross-sectional analysis characterizing patients transplanted and enrolled in the SPLIT registry between 2011 and 2018. All patients, <18 years of age, received a first liver-only, a combined liver-kidney, or a combined liver-pancreas transplant during this study period.

RESULTS

A total of 1911 recipients from 39 participating centers in North America were registered. Indications included biliary atresia (38.5%), metabolic disease (19.1%), tumors (11.7%), and fulminant liver failure (11.5%). Greater than 50% of recipients were transplanted as either Status 1A/1B or with a MELD/PELD exception score. Incompatible transplants were performed in 4.1%. Kaplan-Meier estimates of 1-year patient and graft survival were 97.3% and 96.6%. First 30 days of surgical complications included reoperation (31.7%), hepatic artery thrombosis (6.3%), and portal vein thrombosis (3.2%). In the first 90 days, biliary tract complications were reported in 13.6%. Acute cellular rejection during first year was 34.7%. At 1 and 2 years of follow-up, 39.2% and 50.6% had normal liver tests on monotherapy (tacrolimus or sirolimus). Further surgical, survival, allograft function, and complications are detailed.

Gram-negative infection as an unusual cause of endocarditis in a hemodialysis patient

Gram-negative endocarditis is rare and it has high mortality if there is a delay in diagnosis and treatment. Gram-negative organisms should be considered in the differential diagnosis of IE in hemodialysis patients. Central lineassociated bloodstream infections (CLABSIs) can be prevented by following sterile measures during catheter insertion and proper management of catheter site.

PlantMirnaT: miRNA and mRNA integrated analysis fully utilizing characteristics of plant sequencing data

miRNA is known to regulate up to several hundreds coding genes, thus the integrated analysis of miRNA and mRNA expression data is an important problem. Unfortunately, the integrated analysis is challenging since it needs to consider expression data of two different types, miRNA and mRNA, and target relationship between miRNA and mRNA is not clear, especially when microarray data is used. Fortunately, due to the low sequencing cost, small RNA and RNA sequencing are routinely processed and we may be able to infer regulation relationships between miRNAs and mRNAs more accurately by using sequencing data. However, no method is developed specifically for sequencing data. Thus we developed PlantMirnaT, a new miRNA-mRNA integrated analysis system. To fully leverage the power of sequencing data, three major features are developed and implemented in PlantMirnaT. First, we implemented a plant-specific short read mapping tool based on recent discoveries on miRNA target relationship in plant. Second, we designed and implemented an algorithm considering miRNA targets in the full intragenic region, not just 3' UTR. Lastly but most importantly, our algorithm is designed to consider quantity of miRNA expression and its distribution on target mRNAs. The new algorithm was used to characterize rice under drought condition using our proprietary data. Our algorithm successfully discovered that two miRNAs, miRNA1425-5p, miRNA 398b, that are involved in suppression of glucose pathway in a naturally drought resistant rice, Vandana. The system can be downloaded at https://sites.google.com/site/biohealthinformaticslab/resources.

Protective effects of peroxiredoxin 6 overexpression on amyloid β-induced apoptosis in PC12 cells

Oxidative stress triggered by amyloid beta (Aβ) accumulation contributes substantially to the pathogenesis of Alzheimer's disease (AD). In the present study, we examined the involvement of the antioxidant activity of peroxiredoxin 6 (Prdx 6) in protecting against Aβ25-35-induced neurotoxicity in rat PC12 cells. Treatment of PC12 cells with Aβ25-35 resulted in a dose- and time-dependent cytotoxicity that was associated with increased accumulation of intracellular reactive oxygen species (ROS) and mitochondria-mediated apoptotic cell death, including activation of Caspase 3 and 9, inactivation of poly ADP-ribosyl polymerse (PARP), and dysregulation of Bcl-2 and Bax. This apoptotic signaling machinery was markedly attenuated in PC12 cells that overexpress wild-type Prdx 6, but not in cells that overexpress the C47S catalytic mutant of Prdx 6. This indicates that the peroxidase activity of Prdx 6 protects PC12 cells from Aβ25-35-induced neurotoxicity. The neuroprotective role of the antioxidant Prdx 6 suggests its therapeutic and/or prophylactic potential to slow the progression of AD and limit the extent of neuronal cell death caused by AD.

PA612 Double Bubble Tubular Film Process – Processability and Structure Development

Biaxially oriented Polyamide 612 (PA612) films made by double bubble tubular film extrusion were characterized. The processing characteristics of the polymer in the double bubble process were investigated. The development of crystallinity and orientation in the films was clearly considered. First bubble PA612 films showed a low level of crystallinity (X = 7.7%). Differential scanning calorimetry (DSC) indicated that the first bubble PA 612 films experienced a considerable increase in glass transition temperature (Tg), cold crystallization temperature (Tc) and crystallinity during aging at room conditions. The second bubble films were more highly crystalline (X = 22 to 28%) with poorly grown β unit cells. The WAXD and SAXS patterns showed that the crystallites of double bubble PA612 films became more perfect by annealing in a boiling 20% formic acid solution, resulting in a well-developed triclinic α crystals coexisting with minor proportion of β phase. The WAXD and SAXS patterns indicated that crystallography planes and lamellae in the second bubble films were oriented depending on SBUR × SDDR (second blow-up ratio x second draw down ratio). White-Spruiell biaxial orientation factors were calculated with the WAXD pole figure data. The hydrogen bonding (0k0) planes of biaxial double bubble films were found by WAXD to be aligned parallel to the sheet surface before and after annealing.

Direct evidence of allele-specific binding of CTCF and MeCP2 to Tsix in a HPRT-deficient female F₁ hybrid mouse cell line

Mammalian dosage compensation requires silencing of one of the two X chromosomes in females and is controlled by the X inactivation center (Xic). Xic contains many of the regulatory elements for the mutual interplay of X-inactive specific transcript (Xist) and Tsix, the antisense counterpart of Xist. The regulatory elements control X chromosome inactivation (XCI) via the formation of DNA-DNA and DNA-protein complexes with cis- and trans-acting factors. However, the process-dependent regulation of Xist/Tsix by these elements in each XCI process remains largely unknown. In this study, a 6-thioguanine-resistant female F(1) hybrid mouse cell line (designated HOBMSKI2) was constructed from a cross between a female HPRT-deficient transgenic mouse (designated BM3) and a male wild type Mus spretus mouse (designated MS), which enabled the direct discrimination of both allele-specific expression of X-linked genes and allele-specific binding of proteins associated with XCI due to DNA polymorphisms between BM3 and MS. Using this cell line, we found that Tsix on the active X chromosome (Xa) was not expressed in somatic cells despite the fact that CTCF, which ensures Tsix expression in embryonic stem cells, was still bound to the 5' end of Tsix on Xa, implying that CTCF may function differently during each XCI process and its trans-activating activity for Tsix expression may be lost in the maintenance process. In addition, the monoallelic expression of Tsix on Xa was inhibited by epigenetic modification of the chromatin in the maintenance process, which was mediated by protein complexes recruited by MeCP2. The results indicate the value of HOBMSKI2 in directly detecting the allele-specific binding of CTCF and MeCP2 to the 5' end of Tsix. The HOBMSKI2 mouse line is a versatile and useful resource for studying the molecular mechanism of the XCI process.

Cloning and sequence analysis of the estA gene encoding enzyme for producing (R)-beta-acetylmercaptoisobutyric acid from Pseudomonas aeruginosa 1001

The estA gene encoding the enzyme that catalyzes the production of (R)-beta-acetylmercaptoisobutyric acid from (R,S)-ester from Pseudomonas aeruginosa 1001, was cloned in Escherichia coli and its nucleotide sequence was determined, revealing the presumed open reading frame encoding a polypeptide of 316 amino acid residues (948 nucleotides). The overall A + T and C + G compositions were 32.59% and 67.41%, respectively. The amino acid sequence of the estA gene product showed a significant similarity with that of the triacylglycerol lipase from Psychrobacter immobilis (38% identity), triacylglycerol lipase from Moraxella sp. (36% identity), and two forms of carboxyl esterases from Acinetobacter calcoaceticus (17% and 17% identities). The deduced amino acid sequences have a pentapeptide consensus sequence, G-X-S-X-G, having an active serine residue, and another active site, dipeptides H-G, located at 70-100 amino acids upstream of the G-X-S-X-G consensus sequence.

Artifact-resistant power-efficient design of finger-ring plethysmographic sensors

A miniaturized, telemetric, photoplethysmograph (PPG) sensor for long-term, continuous monitoring is presented in this paper. The sensor, called a "ring sensor," is attached to a finger base for monitoring beat-to-beat pulsation, and the data is sent to a host computer via a radio-frequency transmitter. Two major design issues are addressed: one is to minimize motion artifact and the other is to minimize the consumption of battery power. An efficient double ring design is developed to lower the influence of external force, acceleration, and ambient light, and to hold the sensor gently and securely on the skin, so that the circulation at the finger may not be obstructed. Total power consumption is analyzed in relation to characteristics of individual components, sampling rate, and CPU clock speed. Optimal operating conditions are obtained for minimizing the power budget. A prototype ring sensor is designed and built based on the power budget analysis and the artifact-resistive attachment method. It is verified through experiments that the ring sensor is resistant to interfering forces and acceleration acting on the ring body. Benchmarking tests with FDA-approved PPG and electrocardiogram reveal that the ring sensor is comparable to those devices in detecting beat-to-beat pulsation despite disturbances.

The crystal structure of the nitrogen regulation fragment of the yeast prion protein Ure2p

The yeast nonchromosomal gene [URE3] is due to a prion form of the nitrogen regulatory protein Ure2p. It is a negative regulator of nitrogen catabolism and acts by inhibiting the transcription factor Gln3p. Ure2p residues 1--80 are necessary for prion generation and propagation. The C-terminal fragment retains nitrogen regulatory activity, albeit somewhat less efficiently than the full-length protein, and it also lowers the frequency of prion generation. The crystal structure of this C-terminal fragment, Ure2p(97--354), at 2.3 A resolution is described here. It adopts the same fold as the glutathione S-transferase superfamily, consistent with their sequence similarity. However, Ure2p(97--354) lacks a properly positioned catalytic residue that is required for S-transferase activity. Residues within this regulatory fragment that have been indicated by mutational studies to influence prion generation have been mapped onto the three-dimensional structure, and possible implications for prion activity are discussed.

Crystallization and preliminary X-Ray diffraction analysis of glutaryl-7-aminocephalosporanic acid acylase from Pseudomonas sp. GK16

Glutaryl-7-aminocephalosporanicacid acylase from Pseudomonas sp. GK16 produces glutaryl-7-aminocephalosporanic acid, a key intermediate for the synthesis of cephem antibiotics. Sequence alignment suggests that the enzyme may belong to the N-terminal nucleophile hydrolase superfamily including penicillin G acylase. The enzyme is an (alphabeta)(2) heterotetramer of two nonidentical subunits. These subunits are derived from a nascent precursor polypeptide that is cleaved proteolytically through a two-step autocatalytic process upon folding. The enzyme has been crystallized using the vapor diffusion method. A bipyramidal crystal form was obtained from a solution containing polyethylene glycol (MW 3350) and calcium chloride. Complete diffraction data sets have been collected up to 2.8 A resolution. The crystal is tetragonal with the space group P4(1)2(1)2 or P4(3)2(1)2 and the unit cell parameters are a = b = 73.5 A, c = 380.3 A. Considerations of the possible values of V(m) account for the presence of a tetramer in the asymmetric unit.

Sustained formation of focal adhesions with paxillin in morphological differentiation of PC12 cells

Differentiation of PC12 cells triggered by nerve growth factor (NGF) is characterized by several well-defined events including induction of a set of neuron-specific genes, gain of membrane excitability, and morphological changes such as neurite outgrowth. Here we report that K252a, a protein kinase inhibitor, converts the proliferation signal of epidermal growth factor (EGF) into the morphological differentiation signal without inducing the sustained activation of ERK and the expression of neurofilament. Major effects of EGF/K252a, found also in the NGF-treated cells, are the sustained mobility shift of paxillin in SDS-PAGE and the promoted association of Crk-II with paxillin. These effects explain the prominent and robust development of peripheral focal adhesion assembly and stress fiber-like structures observed in the early stages of PC12 cell differentiation. These results suggest a model that cytoskeletal reorganization via focal adhesion assembly triggered by NGF provides a signal required for the morphological differentiation of PC12 cells.

Crystallization and preliminary crystallographic study of triple-helical DNA

Single crystals of d(CTCCT(S)CCGCGCG).d(CGCGCGGAG) have been grown by the vapor-diffusion method using 2-methyl-2,4-pentanediol as a precipitant. The crystals are tetragonal, space group P4(2), with unit-cell parameters a = b = 53.8, c = 43.1 A, and diffract to 1.8 A resolution at a synchrotron X-ray beamline. In the crystal, the asymmetric unit contains one copy of the construct. The two halves of the structure are related by non-crystallographic twofold symmetry. These observations are consistent with the conclusion that the sequences of the 12-mer and 9-mer oligonucleotides form a duplex DNA at one end and a triplex DNA at the other end.

Structure of a triple helical DNA with a triplex-duplex junction

Extended purine sequences on a DNA strand can lead to the formation of triplex DNA in which the third strand runs parallel to the purine strand. Triplex DNA structures have been proposed to play a role in gene expression and recombination and also have potential application as antisense inhibitors of gene expression. Triplex structures have been studied in solution by NMR, but have hitherto resisted attempts at crystallization. Here, we report a novel design of DNA sequences, which allows the first crystallographic study of DNA segment containing triplexes and its junction with a duplex. In the 1.8 A resolution structure, the sugar-phosphate backbone of the third strand is parallel to the purine-rich strand. The bases of the third strand associate with the Watson and Crick duplex via Hoogsteen-type interactions, resulting in three consecutive C(+).GC, BU.ABU (BU = 5-bromouracil), and C(+).GC triplets. The overall conformation of the DNA triplex has some similarity to the B-form, but is distinct from both A- and B-forms. There are large changes in the phosphate backbone torsion angles (particularly gamma) of the purine strand, probably due to the electrostatic interactions between the phosphate groups and the protonated cytosine. These changes narrow the minor groove width of the purine-Hoogsteen strands and may represent sequence-specific structural variations of the DNA triplex.

Promotion of skeletal muscle differentiation by K252a with tyrosine phosphorylation of focal adhesion: a possible involvement of small GTPase Rho

K252a, a protein kinase inhibitor, acts as a neurotrophic factor in several neuronal cells. In this study we show that K252a enhanced the differentiation of C2C12 myoblasts as well as tyrosine phosphorylation of several focal adhesion-associated proteins including p130(Cas), focal adhesion kinase, and paxillin. The tyrosine phosphorylation of these proteins, reaching a maximum at 30 min after K252a treatment, closely correlated with the colocalization of these proteins in focal adhesion complexes and the coimmunoprecipitation of these proteins with p130(Cas). In addition, K252a stimulated longitudinal development of stress fiber-like structures and cell-matrix interaction in postmitotic myoblasts and eventually formation of well-developed myofibrils in multinucleated myotubes. Herbimycin A, a potent inhibitor of Src family kinases, and cytochalasin D, a selective disrupting-agent of actin filament, completely inhibited K252a-induced tyrosine phosphorylation as well as myoblast differentiation. Similar inhibitory effect was observed in the cells scrape loaded with a Rho inhibitor, C3 transferase, and the treatment of K252a induced a rapid translocation of Rho. These results are consistent with the model that Rho-dependent tyrosine phosphorylation of focal adhesion-associated proteins plays an important role in skeletal muscle differentiation.

Structural requirements for marbox function in transcriptional activation of mar/sox/rob regulon promoters in Escherichia coli: sequence, orientation and spatial relationship to the core promoter

The promoters of the mar/sox/rob regulon of Escherichia coli contain a binding site (marbox) for the homologous transcriptional activators MarA, SoxS and Rob. In spite of data from footprinting studies, the marbox has not been precisely defined because of its degeneracy and asymmetry and seemingly variable location with respect to the -10 and -35 hexamers for RNA polymerase (RNP) binding. Here, we use DNA retardation studies and hybrid promoters to identify optimally binding 20 bp minimal marboxes from a number of promoters. This has yielded a more defined marbox consensus sequence (AYnGCACnnWnnRYYAAAYn) and has led to the demonstration that some marboxes are inverted relative to others. Using transcriptional fusions to lacZ, we have found that only one marbox orientation is functional at a given location. Moreover, the functional orientation is determined by marbox location: marboxes that are 15 or more basepairs upstream of the -35 hexamer are oriented opposite those closer to the -35 hexamer. Marbox orientation and the spacing between marbox and signals for RNP binding are critical for transcriptional activation, presumably to align MarA with RNP.

Neuregulin stimulates myogenic differentiation in an autocrine manner

During myogenesis, mononucleated myoblasts form multinucleated myotubes by membrane fusion. Efficiency of this intercellular process can be maximized by a simultaneous progress, with a time window, of other neighboring myoblasts in the differentiation program. This phenomenon has been described as the community effect. It proposes the existence of a molecule that acts as a differentiation-inducing signal to a group of identical cells. Here, we show that neuregulin is a strong candidate for this molecule in myoblast differentiation. The expression of neuregulin increased rapidly but transiently at early stage of differentiation of rat L6 cells. Neuregulin showed a potent differentiation-promoting activity in membrane fusion and expression of myosin heavy chain. The antibodies raised against neuregulin and its cognate receptor ErbB3, which were capable of neutralizing the signal pathway, inhibited myotube formation and expression of myosin heavy chain in both L6 cells and primary rat myoblasts. The progress of differentiation was mostly halted after the expression of myogenin and cell cycle arrest. These results suggest that the activation of an autocrine signaling of neuregulin may provide a basic mechanism for the community effect observed in the differentiation of the embryonic muscle cells.

Anatomical study of the maxillary tuberosity in Japanese men

The placement of dental implants in the molar region of the maxilla is often difficult because of the presence of the maxillary sinus. It has recently been postulated that the pillar of bone consisting of the maxillary tuberosity, the pterygoid process of the sphenoid bone, and the pyramidal process of the palatine bone, which is located at the posterior part of the maxilla, is suitable for fixing implants in the maxilla. In this study, we morphometrically examined the figure of the pillar of bone in dentate and edentulous maxillary bone specimens. The posterior part of the maxilla, including the pterygoid process of the sphenoid bone and pyramidal process of the palatine bone was embedded in polyester resin. Serial transverse sections 500 microns thick were prepared, and soft X-ray photographs were taken. Three-dimensional images of the pillar of bone were reconstructed from the contour in the soft X-ray images, and the height inclination angles, and volume of the pillar were measured. In dentulous specimens, the imaginary approximation line of the center of the gravity of the pillar of bone in the posterior part of the maxilla was inclined antero-posteriorly at an angle of 76.5 +/- 3.0 degrees from the anterior to posterior direction against the Frankfurt horizontal plane and bucco-palatally at 17.2 +/- 2.7 degrees to the medial direction against the sagittal plane. In edentulous specimens, the pillar of bone was inclined antero-posteriorly at 67.3 +/- 5.0 degrees against the Frankfurt horizontal plane and bucco-palatally at 14.1 +/- 2.1 degrees against the sagittal plane. The volume of the pillar of bone was greater in edentulous specimens than those in the dentulous specimens. The present results will enable setting up a standard for implant surgery dentulous specimens.

Zymogen proteolysis within the pancreatic acinar cell is associated with cellular injury

The pathological activation of digestive zymogens within the pancreatic acinar cell probably plays a central role in initiating many forms of pancreatitis. To examine the relationship between zymogen activation and acinar cell injury, we investigated the effects of secretagogue treatment on isolated pancreatic acini. Immunofluorescence studies using antibodies to the trypsinogen-activation peptide demonstrated that both CCK (10(-7) M) hyperstimulation and bombesin (10(-5) M) stimulation of isolated acini resulted in trypsinogen processing to trypsin. These treatments also induced the proteolytic processing of procarboxypeptidase A1 to carboxypeptidase A1 (CA1). After CCK hyperstimulation, most CA1 remained in the acinar cell. In contrast, the CA1 generated by bombesin was released from the acinar cell. CCK hyperstimulation of acini was associated with cellular injury, whereas bombesin treatment did not induce injury. These studies suggest that 1) proteolytic zymogen processing occurs within the pancreatic acinar cell and 2) both zymogen activation and the retention of enzymes within the acinar cell may be required to induce injury.

A novel DNA-binding motif in MarA: the first structure for an AraC family transcriptional activator

A crystal structure for a member of the AraC prokaryotic transcriptional activator family, MarA, in complex with its cognate DNA-binding site is described. MarA consists of two similar subdomains, each containing a helix-turn-helix DNA-binding motif. The two recognition helices of the motifs are inserted into adjacent major groove segments on the same face of the DNA but are separated by only 27 A thereby bending the DNA by approximately 35 degrees. Extensive interactions between the recognition helices and the DNA major groove provide the sequence specificity.

Basic fibroblast growth factor stimulates angiogenesis in the hindlimb of hyperglycemic rats

Angiogenic growth factors including basic fibroblast growth factor (bFGF) have therapeutic value for chronic ischemia in nondiabetic animals. However, angiogenic therapy for chronic ischemia in a background of diabetes remains unexplored. In the present study, we evaluated the effects of exogenous bFGF on angiogenesis in streptozotocin-induced diabetic rats with ischemic and nonischemic limbs. We produced ischemia of the left lower limb by excising the superficial femoral artery. At 2 weeks, the rats received an intramuscular injection of vehicle (group A), 0.3 microg bFGF/day (group B), or 1 microg bFGF/day (group C), daily for 2 weeks. At 4 weeks, we assessed limb angiogenesis by skeletal muscle capillary density (cap/mm2) and capillary per muscle fiber ratio (cap/F) counts. Group C had significantly higher mean levels compared to group A for calf capillary density (P < 0.0024) and capillary per muscle fiber ratio in both thigh (P < 0.0015) and calf (P < 0.0001). There was a trend toward increased mean capillary per muscle fiber ratio with increasing dose. This trend was significant in the calf (P < 0.0015) and just missed statistical significance in the thigh. There was a similar trend in calf capillary density. We conclude that exogenous bFGF enhances angiogenesis and, possibly, collateral circulation in ischemic limbs of diabetic rats.

Inhibitors of the proteasome block the myogenic differentiation of rat L6 myoblasts

Myogenesis is characterized by membrane fusion and accumulation of muscle specific proteins. We have previously shown that nitric oxide acts as a messenger for membrane fusion. Here we show that inhibitors of the proteasome, such as lactacystin, reversibly block both the fusion of L6 myoblasts and the accumulation of muscle specific proteins, such as myosin heavy chain (MHC). The inhibitors also reversibly prevented the induction of the NF-kappaB activity, which is required for the expression of nitric oxide synthase (NOS). Moreover, the inhibition of the NF-kappaB activity occurred in parallel with that of the NOS activity upon treatment with increasing concentrations of lactacystin. While pyrrolidine dithiocarbamate, an inhibitor of NF-kappaB, blocked both membrane fusion and accumulation of MHC, N(G)-monomethyl-L-arginine, a specific inhibitor of NOS, inhibited only the fusion. These results suggest that the proteasome plays an essential role in the regulation of myogenic differentiation through the activation of NF-kappaB and that the target of NF-kappaB for the expression of muscle specific proteins is distinct from that for myoblast fusion.

Cryocrystallography and microspectrophotometry of a mutant (alpha D60N) tryptophan synthase alpha 2 beta 2 complex reveals allosteric roles of alpha Asp60

We have investigated the role of Asp60 of the alpha-subunit in allosteric communication between the tryptophan synthase alpha- and beta-subunits. Crystallographic and microspectrophotometric studies have been carried out on a mutant (alpha D60N) tryptophan synthase alpha 2 beta 2 complex which has no observable alpha-activity, but has substantial beta-activity. Single-crystal polarized absorption spectra indicate that the external aldimine is the predominant L-serine intermediate and that the amount of the intermediate formed is independent of pH, monovalent cations, and allosteric effectors. The three-dimensional structure is reported for this mutant enzyme complexed with indole 3-propanol phosphate bound to the alpha-site and L-serine bound to the beta-site (alpha D60N-IPP-Ser), and this structure is compared with that of the unliganded mutant enzyme (alpha D60N). In the complex, L-serine forms a stable external aldimine with the pyridoxal phosphate coenzyme at the active site of the beta-subunit. The conformation of the unliganded mutant is almost identical to that of the wild type enzyme. However, the structure of the mutant complexed with IPP and serine exhibits ligand-induced conformational changes much smaller than those observed previously for another mutant enzyme in the presence of the same ligands (beta K87T-IPP-Ser) [Rhee, S., Parris, K. D., Hyde, C. C., Ahmed, S. A., Miles, E. W., and Davies, D. R. (1997) Biochemistry 36, 7664-7680]. The alpha D60N-IPP-Ser alpha 2 beta 2 complex does not undergo the following ligand-induced conformational changes: (1) the closure of the alpha-subunit loop 6 (residues 178-191), (2) the movement of the mobile subdomain (residues 93-189) of the beta-subunit, and (3) the rotation of the alpha-subunit relative to the beta-subunit. These observations show that alpha Asp60 plays important roles in the closure of loop 6 and in allosteric communication between the alpha- and beta-subunits.

Cryo-crystallography of a true substrate, indole-3-glycerol phosphate, bound to a mutant (alphaD60N) tryptophan synthase alpha2beta2 complex reveals the correct orientation of active site alphaGlu49

The reversible cleavage of indole-3-glycerol by the alpha-subunit of tryptophan synthase has been proposed to be catalyzed by alphaGlu49 and alphaAsp60. Although previous x-ray crystallographic structures of the tryptophan synthase alpha2beta2 complex showed an interaction between the carboxylate of alphaAsp60 and the bound inhibitor indole-3-propanol phosphate, the carboxylate of alphaGlu49 was too distant to play its proposed role. To clarify the structural and functional roles of alphaGlu49, we have determined crystal structures of a mutant (alphaD60N) alpha2beta2 complex in the presence and absence of the true substrate, indole-3-glycerol phosphate. The enzyme in the crystal cleaves indole-3-glycerol phosphate very slowly at room temperature but not under cryo-conditions of 95 K. The structure of the complex with the true substrate obtained by cryo-crystallography reveals that indole-3-glycerol phosphate and indole-3-propanol phosphate have similar binding modes but different torsion angles. Most importantly, the side chain of alphaGlu49 interacts with 3-hydroxyl group of indole-3-glycerol phosphate as proposed. The movement of the side chain of alphaGlu49 into an extended conformation upon binding the true substrate provides evidence for an induced fit mechanism. Our results demonstrate how cryo-crystallography and mutagenesis can provide insight into enzyme mechanism.

Telenzepine-sensitive muscarinic receptors on rat pancreatic acinar cells

To identify the muscarinic subtype present on the rat pancreatic acinar cell, we examined the effects of different muscarinic receptor antagonists on amylase secretion and proteolytic zymogen processing in isolated rat pancreatic acini. Maximal zymogen processing required a concentration of carbachol 10- to 100-fold greater (10(-3) M) than that required for maximal amylase secretion (10(-5) M). Although both secretion and conversion were inhibited by the M3 antagonist 4-diphenylacetoxy-N-methyl-piperidine (4-DAMP) (50% inhibition approximately 6 x 10(-7) M and 1 x 10(-8) M, respectively), the most potent inhibitor was the M1 antagonist telenzepine (50% inhibition approximately 5 x 10(-10) M and 1 x 10(-11) M, respectively). Pirenzepine, another M1 antagonist, and the M2 antagonist methoctramine did not reduce amylase secretion or zymogen processing in concentrations up to 1 x 10(-5) M. Analysis of acinar cell muscarinic receptor by PCR revealed expression of both m1 and m3 subtypes. The pancreatic acinar cell has a distinct pattern of muscarinic antagonist sensitivity (telenzepine >> 4-DAMP > pirenzepine) with respect to both amylase secretion and zymogen conversion.

Refinement and comparisons of the crystal structures of pig cytosolic aspartate aminotransferase and its complex with 2-methylaspartate

Two high resolution crystal structures of cytosolic aspartate aminotransferase from pig heart provide additional insights into the stereochemical mechanism for ligand-induced conformational changes in this enzyme. Structures of the homodimeric native structure and its complex with the substrate analog 2-methylaspartate have been refined, respectively, with 1.74-A x-ray diffraction data to an R value of 0.170, and with 1.6-A data to an R value of 0.173. In the presence of 2-methylaspartate, one of the subunits (subunit 1) shows a ligand-induced conformational change that involves a large movement of the small domain (residues 12-49 and 327-412) to produce a "closed" conformation. No such transition is observed in the other subunit (subunit 2), because crystal lattice contacts lock it in an "open" conformation like that adopted by subunit 1 in the absence of substrate. By comparing the open and closed forms of cAspAT, we propose a stereochemical mechanism for the open-to-closed transition that involves the electrostatic neutralization of two active site arginine residues by the negative charges of the incoming substrate, a large change in the backbone (phi,psi) conformational angles of two key glycine residues, and the entropy-driven burial of a stretch of hydrophobic residues on the N-terminal helix. The calculated free energy for the burial of this "hydrophobic plug" appears to be sufficient to serve as the driving force for domain closure.

Crystal structures of a mutant (betaK87T) tryptophan synthase alpha2beta2 complex with ligands bound to the active sites of the alpha- and beta-subunits reveal ligand-induced conformational changes

Three-dimensional structures are reported for a mutant (betaK87T) tryptophan synthase alpha2beta2 complex with either the substrate L-serine (betaK87T-Ser) or product L-tryptophan (betaK87T-Trp) at the active site of the beta-subunit, in which both amino acids form external aldimines with the coenzyme, pyridoxal phosphate. We also present structures with L-serine bound to the beta site and either alpha-glycerol 3-phosphate (betaK87T-Ser-GP) or indole-3-propanol phosphate (betaK87T-Ser-IPP) bound to the active site of the alpha-subunit. The results further identify the substrate and product binding sites in each subunit and provide insight into conformational changes that occur upon formation of these complexes. The two structures having ligands at the active sites of both alpha- and beta-subunits reveal an important new feature, the ordering of alpha-subunit loop 6 (residues 179-187). Closure of loop 6 isolates the active site of the alpha-subunit from solvent and results in interaction between alphaThr183 and the catalytic residue alphaAsp60. Other conformational differences between the wild type and these two mutant structures include a rigid-body rotation of the alpha-subunit of approximately 5 degrees relative to the beta-subunit and large movements of part of the beta-subunit (residues 93-189) toward the rest of the beta-subunit. Much smaller differences are observed in the betaK87T-Ser structure. Remarkably, binding of tryptophan to the beta active site results in conformational changes very similar to those observed in the betaK87T-Ser-GP and betaK87T-Ser-IPP structures, with exception of the disordered alpha-subunit loop 6. These large-scale changes, the closure of loop 6, and the movements of a small number of side chains in the alpha-beta interaction site provide a structural base for interpreting the allosteric properties of tryptophan synthase.

Importance of conserved and variable C-terminal residues for the activity and thermal stability of the beta subunit of tryptophan synthase

To assess the functional roles of helix 13 and of the conserved and variable residues in the C-terminal region (residues 378-397) of the tryptophan synthase beta subunit, we have constructed four C-terminal truncations and 12 point mutations. The effects of these mutations on kinetic and spectroscopic properties and thermal stability are reported here. The mutant beta subunits all form stable alpha2beta2 complexes that have been purified to homogeneity. The mutant alpha2beta2 complexes are divided into two classes on the basis of activity in the reaction of L-serine with indole to form tryptophan. Class I enzymes, which have mutations at Arg-379 or Asp-381 or truncations (384-397 or 385-397), exhibit significant activity (1-38% of wild type). Class II enzymes, which have mutations at Lys-382 or Asp-383 or truncations (382-397 or 383-397), exhibit very low activity (<1% of wild type). Although Class II enzymes have drastically reduced activity in the reaction of L-serine with indole and an altered distribution of enzyme-substrate intermediates in the reaction of L-serine with beta-mercaptoethanol, they retain activity in the reaction of beta-chloro-L-alanine with indole. Correlation of the results with the three-dimensional structure of the alpha2beta2 complex suggests that Lys-382 and Asp-383 serve important roles in a proposed "open" to "closed" conformational change that occurs in the reactions of L-serine. Because mutant beta subunits having C-terminal truncations (383-397 or 384-397) undergo much more rapid thermal inactivation at 60 degrees C than the wild type beta subunit, the C-terminal helix 13 stabilizes the beta subunit.