Fine-Tuning the Performance of Ultraflexible Organic Complementary Circuits on a Single Substrate via a Nanoscale Interfacial Photochemical Reaction

Flexible electronics has paved the way toward the development of next-generation wearable and implantable healthcare devices, including multimodal sensors. Integrating flexible circuits with transducers on a single substrate is desirable for processing vital signals. However, the trade-off between low power consumption and high operating speed is a major bottleneck. Organic thin-film transistors (OTFTs) are suitable for developing flexible circuits owing to their intrinsic flexibility and compatibility with the printing process. We used a photoreactive insulating polymer poly((±)endo,exo-bicyclo[2.2.1]hept-ene-2,3-dicarboxylic acid, diphenylester) (PNDPE) to modulate the power consumption and operating speed of ultraflexible organic circuits fabricated on a single substrate. The turn-on voltage (V _on) of the p- and n-type OTFTs was controlled through a nanoscale interfacial photochemical reaction. The time-of-flight secondary ion mass spectrometry revealed the preferential occurrence of the PNDPE photochemical reaction in the vicinity of the semiconductor-dielectric interface. The power consumption and operating speed of the ultraflexible complementary inverters were tuned by a factor of 6 and 4, respectively. The minimum static power consumption was 30 ± 9 pW at transient and 4 ± 1 pW at standby. Furthermore, within the tuning range of the operating speed and at a supply voltage above 2.5 V, the minimum stage delay time was of the order of hundreds of microseconds. We demonstrated electromyogram measurements to emphasize the advantage of the nanoscale interfacial photochemical reaction. Our study suggests that a nanoscale interfacial photochemical reaction can be employed to develop imperceptible and wearable multimodal sensors with organic signal processing circuits that exhibit low power consumption.

Heterogeneous Functional Dielectric Patterns for Charge-Carrier Modulation in Ultraflexible Organic Integrated Circuits

Flexible electronics have gained considerable attention for application in wearable devices. Organic transistors are potential candidates to develop flexible integrated circuits (ICs). A primary technique for maximizing their reliability, gain, and operation speed is the modulation of charge-carrier behavior in the respective transistors fabricated on the same substrate. In this work, heterogeneous functional dielectric patterns (HFDP) of ultrathin polymer gate dielectrics of poly((±)endo,exo-bicyclo[2.2.1]hept-ene-2,3-dicarboxylic acid, diphenylester) (PNDPE) are introduced. The HFDP that are obtained via the photo-Fries rearrangement by ultraviolet radiation in the homogeneous PNDPE provide a functional area for charge-carrier modulation. This leads to programmable threshold voltage control over a wide range (-1.5 to +0.2 V) in the transistors with a high patterning resolution, at 2 V operational voltage. The transistors also exhibit high operational stability over 140 days and under the bias-stress duration of 1800 s. With the HFDP, the performance metrics of ICs, for example, the noise margin and gain of the zero-V_GS load inverters and the oscillation frequency of ring oscillators are improved to 80%, 1200, and 2.5 kHz, respectively, which are the highest among the previously reported zero-V_GS -based organic circuits. The HFDP can be applied to much complex and ultraflexible ICs.

Heterogeneous Glioma Cell Invasion Under Interstitial Flow Depending on Their Differentiation Status

Glioblastoma (GBM) is the most common and lethal type of malignant brain tumor. A deeper mechanistic understanding of the invasion of heterogeneous GBM cell populations is crucial to develop therapeutic strategies. A key regulator of GBM cell invasion is interstitial flow. However, the effect of an interstitial flow on the invasion of heterogeneous GBM cell populations composed of glioma initiating cells (GICs) and relatively differentiated progeny cells remains unclear. In the present study, we investigated how GICs invade three-dimensional (3D) hydrogels in response to an interstitial flow with respect to their differentiation status. Microfluidic culture systems were used to apply an interstitial flow to the cells migrating from the cell aggregates into the 3D hydrogel. Phase-contrast microscopy revealed that the invasion and protrusion formation of the GICs in differentiated cell conditions were significantly enhanced by a forward interstitial flow, whose direction was the same as that of the cell invasion, whereas those in stem cell conditions were not enhanced by the interstitial flow. The mechanism of flow-induced invasion was further investigated by focusing on differentiated cell conditions. Immunofluorescence images revealed that the expression of cell-extracellular matrix adhesion-associated molecules, such as integrin β1, focal adhesion kinase, and phosphorylated Src, was upregulated in forward interstitial flow conditions. We then confirmed that cell invasion and protrusion formation were significantly inhibited by PP2, a Src inhibitor. Finally, we observed that the flow-induced cell invasion was preceded by nestin-positive immature GICs at the invasion front and followed by tubulin β3-positive differentiated cells. Our findings provide insights into the development of novel therapeutic strategies to inhibit flow-induced glioma invasion. Impact statement A mechanistic understanding of heterogeneous glioblastoma cell invasion is crucial for developing therapeutic strategies. We observed that the invasion and protrusion formation of glioma initiating cells (GICs) were significantly enhanced by forward interstitial flow in differentiated cell conditions. The expression of integrin β1, focal adhesion kinase, and phosphorylated Src was upregulated, and the flow-induced invasion was significantly inhibited by a Src inhibitor. The flow-induced heterogeneous cell invasion was preceded by nestin-positive GICs at the invasion front and followed by tubulin β3-positive differentiated cells. Our findings provide insights into the development of novel therapeutic strategies to inhibit flow-induced glioma invasion.

Correction to: Comprehensive genetic analyses using targeted next-generation sequencing and genotype-phenotype correlations in 53 Japanese patients with osteogenesis imperfecta

The original article has been corrected.

Ultralow-Noise Organic Transistors Based on Polymeric Gate Dielectrics with Self-Assembled Modifiers

In this study, ultralow 1/f noise organic thin-film transistors (OTFTs) based on parylene gate dielectrics modified with triptycene (Trip) modifiers were fabricated. The fabricated OTFTs showed the lowest 1/f noise level among those of previously reported OTFTs. It is well known that 1/f noise causes degradation of signal integrity in analog and digital circuits. However, conventional OTFTs still possess high 1/f noise levels, and the factors that strongly affect 1/f noise are still ambiguous. In this work, the effect of gate dielectric surface on 1/f noise was investigated. First, by comparing OTFTs composed of various channel lengths, we revealed that contact resistance did not affect 1/f noise. Second, we compared parylene OTFTs with and without a self-assembled Trip modifier layer in terms of 1/f noise and trap density of states (Trap DOS). The experiments revealed that a specific Trip modifier layer suppresses the shallow Trap DOS in the OTFTs, leading to a low 1/f noise. Moreover, the 1/f noise level and Trap DOS of various kinds of OTFTs were comprehensively compared, which highlighted that the 1/f noise of OTFTs strongly depends on the gate dielectric surface. Finally, detailed analysis of the gate dielectric interface led us to conclude that the disorder of gate dielectrics and the crystalline quality of semiconductor films are related to shallow Trap DOS, which correlates with 1/f noise.

Comprehensive genetic analyses using targeted next-generation sequencing and genotype-phenotype correlations in 53 Japanese patients with osteogenesis imperfecta

To elucidate mutation spectrum and genotype-phenotype correlations in Japanese patients with OI, we conducted comprehensive genetic analyses using NGS, as this had not been analyzed comprehensively in this patient population. Most mutations were located on COL1A1 and COL1A2. Glycine substitutions in COL1A1 resulted in the severe phenotype.

INTRODUCTION

Most cases of osteogenesis imperfecta (OI) are caused by mutations in COL1A1 or COL1A2, which encode α chains of type I collagen. However, mutations in at least 16 other genes also cause OI. The mutation spectrum in Japanese patients with OI has not been comprehensively analyzed, as it is difficult to identify using classical Sanger sequencing. In this study, we aimed to reveal the mutation spectrum and genotype-phenotype correlations in Japanese patients with OI using next-generation sequencing (NGS).

METHODS

We designed a capture panel for sequencing 15 candidate OI genes and 19 candidate genes that are associated with bone fragility or Wnt signaling. Using NGS, we examined 53 Japanese patients with OI from unrelated families.

RESULTS

Pathogenic mutations were detected in 43 out of 53 individuals. All mutations were heterozygous. Among the 43 individuals, 40 variants were identified including 15 novel mutations. We found these mutations in COL1A1 (n = 30, 69.8%), COL1A2 (n = 12, 27.9%), and IFITM5 (n = 1, 2.3%). Patients with glycine substitution on COL1A1 had a higher frequency of fractures and were more severely short-statured. Although no significant genotype-phenotype correlation was observed for bone mineral density, the trabecular bone score was significantly lower in patients with glycine substitutions.

CONCLUSION

We identified pathogenic mutations in 81% of our Japanese patients with OI. Most mutations were located on COL1A1 and COL1A2. This study revealed that glycine substitutions on COL1A1 resulted in the severe phenotype among Japanese patients with OI.

Orientation analysis of pentacene molecules in organic field-effect transistor devices using polarization-dependent Raman spectroscopy

Pentacene, an organic molecule, is a promising material for high-performance field effect transistors due to its high charge carrier mobility in comparison to usual semiconductors. However, the charge carrier mobility is strongly dependent on the molecular orientation of pentacene in the active layer of the device, which is hard to investigate using standard techniques in a real device. Raman scattering, on the other hand, is a high-resolution technique that is sensitive to the molecular orientation. In this work, we investigated the orientation distribution of pentacene molecules in actual transistor devices by polarization-dependent Raman spectroscopy and correlated these results with the performance of the device. This study can be utilized to understand the distribution of molecular orientation of pentacene in various electronic devices and thus would help in further improving their performances.

Renewable Wood Pulp Paper Reactor with Hierarchical Micro/Nanopores for Continuous-Flow Nanocatalysis

Continuous-flow nanocatalysis based on metal nanoparticle catalyst-anchored flow reactors has recently provided an excellent platform for effective chemical manufacturing. However, there has been limited progress in porous structure design and recycling systems for metal nanoparticle-anchored flow reactors to create more efficient and sustainable catalytic processes. In this study, traditional paper is used for a highly efficient, recyclable, and even renewable flow reactor by tailoring the ultrastructures of wood pulp. The "paper reactor" offers hierarchically interconnected micro- and nanoscale pores, which can act as convective-flow and rapid-diffusion channels, respectively, for efficient access of reactants to metal nanoparticle catalysts. In continuous-flow, aqueous, room-temperature catalytic reduction of 4-nitrophenol to 4-aminophenol, a gold nanoparticle (AuNP)-anchored paper reactor with hierarchical micro/nanopores provided higher reaction efficiency than state-of-the-art AuNP-anchored flow reactors. Inspired by traditional paper materials, successful recycling and renewal of AuNP-anchored paper reactors were also demonstrated while high reaction efficiency was maintained.

Antibacterial effect of bactericide immobilized in resin matrix

OBJECTIVE

Biomaterials with anti-microbial properties are highly desirable in the oral cavity. Ideally, bactericidal molecules should be immobilized within the biomaterial to avoid unwanted side-effects against surrounding tissues. They may then however loose much of their antibacterial efficiency. The aim of this study was to investigate how much antibacterial effect an immobilized bactericidal molecule still has against oral bacteria.

METHODS

Experimental resins containing 0, 1 and 3% cetylpyridinium chloride (CPC) were polymerized, and the bacteriostatic and bactericidal effects against Streptococcus mutans were determined. Adherent S. mutans on HAp was quantitatively determined using FE-SEM and living cells of S. mutans were quantified using real-time RT-PCR. The amount of CPC released from the 0%-, 1%- and 3%-CPC resin sample into water was spectrometrically quantified using a UV-vis recording spectrophotometer.

RESULTS

UV spectrometry revealed that less than 0.11 ppm of CPC was released from the resin into water for all specimens, which is lower than the minimal concentration generally needed to inhibit biofilm formation. Growth of S. mutans was significantly inhibited on the surface of the 3%-CPC-containing resin coating, although no inhibitory effect was observed on bacteria that were not in contact with its surface. When immersed in water, the antibacterial capability of 3%-CPC resin lasted for 7 days, as compared to resin that did not contain CPC.

SIGNIFICANCE

These results demonstrated that the bactericidal molecule still possessed significant contact bacteriostatic activity when it was immobilized in the resin matrix.

Severe mandibuloacral dysplasia caused by novel compound heterozygous ZMPSTE24 mutations in two Japanese siblings

Mandibuloacral dysplasia (MAD) is a rare autosomal recessive progeroid syndrome, characterized by mandibular hypoplasia, acroosteolysis affecting distal phalanges and clavicles, delayed closure of the cranial sutures, atrophic skin, and lipodystrophy. Recently, mutations in lamin A/C (LMNA) and zinc metalloprotease (ZMPSTE24), involved in post-translational processing of prelamin A to mature lamin A, have been identified in MAD kindreds. We now report novel compound heterozygous mutations in exon 1 (c.121C>T; p.Q41X) and exon 6 (c.743C>T; p.P248L) in ZMPSTE24 in two Japanese sisters, 7- and 3-year old, with severe MAD and characteristic facies and atrophic skin. The older sister had lipodystrophy affecting the chest and thighs but sparing abdomen. Their parents and a brother, who were healthy, had heterozygous mutations. The missense mutation, P248L, was not found in 100 normal subjects of Japanese origin. The mutant Q41X was inactive in a yeast halo assay; however, the mutant P248L retained near normal ZMPSTE24 activity. Immunoblots demonstrated accumulation of prelamin A in the patients' cell lysates from lymphoblasts. The lymphoblasts from the patients also revealed less intense staining for lamin A/C on immunofluorescence. We conclude that ZMPSTE24 deficiency results in accumulation of farnesylated prelamin A, which may be responsible for cellular toxicity and the MAD phenotype.

Gene Profiles during Root Canal Treatment in Experimental Rat Periapical Lesions

The purpose of this study was to profile gene expression in periapical lesions during root canal treatment (RCT). Periapical lesions were induced experimentally by exposing the pulp in Sprague-Dawley rats. After 3 wk, the animals received root canal filling (RCF) and were sacrificed 1 or 4 wk later. From the periapical tissues, total RNA was extracted and processed for cDNA-microarray analysis. The lesions were histologically and radiographically confirmed to expand 4 wk after pulp exposure (inflammation phase) and to stabilize 4 wk after RCF (healing phase). In approximately 30,000 genes on the microarray, 203 genes were up-regulated to more than 5-fold (e.g., IL-1beta), and 864 genes were down-regulated to less than 20% of baseline level (e.g., caspase 8) in inflammation phase. Compared with inflammation phase, we found that 133 genes were up-regulated (e.g., IL-1alpha) and 50 genes were down-regulated (e.g., defensin alpha5) in healing phase. Corresponding to the gene expression profiles, accumulation of IL-1alpha and IL-1beta was observed in the periapical lesions by immunohistochemistry. These gene profiles might be useful in diagnosing the healing process of periapical lesions.

Identification of the type II Na(+)-Pi cotransporter (Npt2) in the osteoclast and the skeletal phenotype of Npt2-/- mice

We previously reported that a type II sodium phosphate (Na(+)-Pi) cotransporter (Npt2) protein is expressed in osteoclasts and that Pi limitation decreases osteoclast-mediated bone resorption in vitro. We also demonstrated that mice homozygous for the disrupted Npt2 gene (Npt2-/-) exhibit a unique age-dependent bone phenotype that is associated with significant hypophosphatemia. In the present study, we sought to identify the Npt2 cDNA in mouse osteoclasts and characterize the impact of Npt2 gene ablation on osteoclast function and bone histomorphometry. We demonstrate that the osteoclast Npt2 cDNA sequence is identical to that of the proximal renal tubule and, thus, not an isoform or splice variant thereof. Histomorphometric analysis revealed that, at 25 days of age, Npt2-/- mice exhibited a reduction in osteoclast number and eroded perimeters, relative to wild-type mice. Moreover, although the number of metaphyseal trabeculae was reduced in 25-day-old Npt2-/- mice, trabecular bone volume was normal due to increased trabecular width. At 115 days of age, the decrease in osteoclast index persisted in Npt2-/- mice relative to wild-type littermates. However, mineralizing and osteoblast surfaces and bone formation rates were increased, and, although trabecular number was still reduced, trabecular bone volume was higher than that of wild-type mice. These data demonstrate a link between osteoclast activity and trabecular development in young Npt2-/- mice, and suggest that an age-related adaptation to Npt2 deficiency is apparent in osteoclast and osteoblast function and bone formation.

Rho family GTPases regulate VEGF-stimulated endothelial cell motility

Migration of endothelial cells induced by vascular endothelial growth factor (VEGF) is a critical step in angiogenesis. Stimulation of motility by growth factors such as VEGF requires interaction with the signal transduction pathways activated by the extracellular matrix (ECM). Here we demonstrate that the Rac GTPase is the critical intersection activated by type 1 collagen ECM and VEGF during stimulation of endothelial cell motility. To analyze the role of the Rho family GTPases in VEGF-stimulated endothelial cell chemotaxis and ECM-stimulated haptotaxis, we transduced the respective fusion proteins in human foreskin dermal endothelial cells using a Tat peptide from the human immunodeficiency virus Tat protein. VEGF signaling required Rac activation during chemotaxis, and Rac and Cdc42 were activated during haptotaxis on type I collagen. Similar to VEGF, Rac activation induced an increase in endothelial cell stress fiber and focal adhesion. Surprisingly, Rho activation was not present in collagen-induced haptotaxis or stimulation of chemotaxis by VEGF, although Rho induced stress fibers and focal adhesions similar to Rac activation. The result of constitutive Rho activation was an inhibition of haptotaxis. Thus, Rac is required and sufficient for the activation of endothelial cell haptotaxis and VEGF-stimulated chemotaxis.

Estrogen deficiency induces bone loss by enhancing T-cell production of TNF-alpha

Estrogen deficiency induces bone loss by upregulating osteoclastogenesis by mechanisms not completely defined. We found that ovariectomy-enhanced T-cell production of TNF-alpha, which, acting through the TNF-alpha receptor p55, augments macrophage colony-stimulating factor-induced (M-CSF-induced) and RANKL-induced osteoclastogenesis. Ovariectomy failed to induce bone loss, stimulate bone resorption, or increase M-CSF- and RANKL-dependent osteoclastogenesis in T-cell deficient mice, establishing T cells as essential mediators of the bone-wasting effects of estrogen deficiency in vivo. These findings demonstrate that the ability of estrogen to target T cells, suppressing their production of TNF-alpha, is a key mechanism by which estrogen prevents osteoclastic bone resorption and bone loss.

Cleavage and phosphorylation of XRCC4 protein induced by X-irradiation

We report the p35 and p60 forms of XRCC4 protein, appearing in human leukemia MOLT-4 or U937 cells following X-irradiation or hyperthermia. p35 appeared in conjunction with the cleavage of DNA-dependent protein kinase catalytic subunit (DNA-PKcs) and the fragmentation of internucleosomal DNA, and was suppressed by Ac-DEVD-CHO. p35 was also produced in vitro by treating MOLT-4 cell lysate with recombinant caspases, suggesting that p35 was a caspase-cleaved fragment of XRCC4 in apoptotic cell death. p60 was sensitive to treatment with phosphatase or wortmannin and was undetectable in M059J cells deficient in DNA-PKcs. However, p60 was found in ataxia-telangiectasia cells after irradiation. These results indicated p60 as a phosphorylated form of XRCC4, requiring DNA-PKcs but not ataxia-telangiectasia mutated (ATM).

Mice lacking beta3 integrins are osteosclerotic because of dysfunctional osteoclasts

Osteoclasts express the alphavbeta3 integrin, an adhesion receptor that has been implicated in bone resorption and that is therefore a potential therapeutic target. To assess the role of this heterodimer in skeletal development in vivo, we engineered mice in which the gene for the beta3 integrin subunit was deleted. Bone marrow macrophages derived from these mutants differentiate in vitro into numerous osteoclasts, thus establishing that alphavbeta3 is not necessary for osteoclast recruitment. Furthermore, the closely related integrin, alphavbeta5, does not substitute for alphavbeta3 during cytokine stimulation or authentic osteoclastogenesis. beta3 knockout mice, but not their heterozygous littermates, develop histologically and radiographically evident osteosclerosis with age. Despite their increased bone mass, beta3-null mice contain 3.5-fold more osteoclasts than do heterozygotes. These mutant osteoclasts are, however, dysfunctional, as evidenced by their reduced ability to resorb whale dentin in vitro and the significant hypocalcemia seen in the knockout mice. The resorptive defect in beta3-deficient osteoclasts may reflect absence of matrix-derived intracellular signals, since their cytoskeleton is distinctly abnormal and they fail to spread in vitro, to form actin rings ex vivo, or to form normal ruffled membranes in vivo. Thus, although it is not required for osteoclastogenesis, the integrin alphavbeta3 is essential for normal osteoclast function.

Granulocyte macrophage-colony stimulating factor reciprocally regulates alphav-associated integrins on murine osteoclast precursors

The integrins alphavbeta3 and alphavbeta3 are expressed reciprocally during murine osteoclastogenesis in vitro. Specifically, immature osteoclast precursors, in the form of bone marrow macrophages, contain exclusively alphavbeta5, surface expression of which declines with commitment to the osteoclast phenotype, while levels of alphavbeta3 increase concomitantly. The distinct functional significance of alphavbeta5 is underscored by the integrin's capacity, unlike alphavbeta3, to mediate both attachment and spreading on ligand, of marrow macrophages, suggesting alphavbeta3 negotiates initial recognition, by osteoclast precursors, of bone matrix. Northern analysis demonstrates changes in the two beta-subunits, and not alphav, are responsible for these alterations. Treatment of early precursors with granulocyte-macrophage colony stimulating factor (GM-CSF) leads to alterations in beta3 and beta5 mRNA and alphavbeta5 and alphavbeta3, paralleling those occurring during osteoclastogenesis. Nuclear run-on and message stability studies demonstrate that while GM-CSF treatment of precursors alters beta5 transcriptionally, the changes in beta3 arise from prolonged mRNA t1/2. Similar to GM-CSF treatment, the rate of beta5 transcription falls during authentic osteoclastogenesis. In contrast to cytokine-induced alphavbeta3, however, that attending osteoclastogenesis reflects accelerated transcription of the beta3-subunit. Thus, while GM-CSF may participate in modulation of alphavbeta5 during osteoclast differentiation, signals other than those derived from the cytokine must regulate expression of alphavbeta3.

The inwardly rectifying potassium channel subunit Kir2.2v (KCNJN1) maps to 17p11.2-->p11.1

Inwardly rectifying K+ (Kir) channels play important roles in various cellular functions in excitable and non-excitable cells. We recently cloned the human genes encoding the Kir channel subunits Kir2.2v (KCNJN1) and Kir2.2 (KCNJ12). However, the physiological role of Kir2.2v has not yet been clarified. Fluorescence in situ hybridization analysis of human metaphase chromosomes assigned both genes to 17p11.2-->p11.1. The presence of hybridization signals in the paracentromeric regions of both chromosomes 17 from two Smith-Magenis syndrome (SMS) patients indicated that Kir2.2v and Kir2.2 are not located within the minimum critical region of this syndrome.

Kir2.2v: a possible negative regulator of the inwardly rectifying K+ channel Kir2.2

We have cloned the human genes encoding the inwardly rectifying K+ (Kir) channel subunits, Kir2.2 (hKir2.2) and its variant, termed hKir2.2v. When expressed in Xenopus oocytes, hKir2.2 produced strong inwardly rectifying K+ currents, whereas the expression of hKir2.2v did not elicit significant currents. Coexpression of hKir2.2v with hKir2.2 showed an hKir2.2v inhibition of hKir2.2 K+ currents, indicating that it acts as a negative regulator of hKir2.2 channel activity. Mutational analysis of hKir2.2v and studies of chimeras between hKir2.2 and hKir2.2v suggest that the intracellular C-terminal region of hKir2.2v participates in the negative regulation of the hKir2.2v channel activity.

Cloning and pharmacological characterization of a fourth P2X receptor subtype widely expressed in brain and peripheral tissues including various endocrine tissues

We have isolated cDNA encoding a fourth member (P2X-4) of the ATP receptor P2X receptor family from a rat pancreatic islet cDNA library. Rat P2X-4 is a protein of 388 amino acids which shares 50%, 49%, and 47% identity with P2X-1, P2X-2, and P2X-3, respectively, and has two putative transmembrane segments. Rat P2X-4 mRNA is widely expressed in brain and peripheral tissues, including various endocrine tissues, and it is also expressed in various hormone-secreting cell lines. We have heterologously expressed the cloned P2X-4 in Xenopus laevis oocytes and have characterized its pharmacological properties. ATP, its analogs and ADP activate cation-selective ion channels. The order of agonist potency is ATP ADP 2-methyl- thioATP(2MeSATP) >> alpha beta-methelene-ATP (alpha betameATP). ATP-evoked currents are only partially blocked by suramin, reactive blue-2, or H2DIDS. The present study suggests that P2X-4, with pharmacological properties distinct from those of P2X-1+, P2X-2, and P2X-3, mediates extracellular ATP-induced biological effects in non-neuronal cells, including endocrine cells, as well as in neuronal cells.

Reconstitution of IKATP: an inward rectifier subunit plus the sulfonylurea receptor

A member of the inwardly rectifying potassium channel family was cloned here. The channel, called BIR (Kir6.2), was expressed in large amounts in rat pancreatic islets and glucose-responsive insulin-secreting cell lines. Coexpression with the sulfonylurea receptor SUR reconstituted an inwardly rectifying potassium conductance of 76 picosiemens that was sensitive to adenosine triphosphate (ATP) (IKATP) and was inhibited by sulfonylureas and activated by diazoxide. The data indicate that these pancreatic beta cell potassium channels are a complex composed of at least two subunits--BIR, a member of the inward rectifier potassium channel family, and SUR, a member of the ATP-binding cassette superfamily. Gene mapping data show that these two potassium channel subunit genes are clustered on human chromosome 11 at position 11p15.1.

Cloning and functional characterization of a novel ATP-sensitive potassium channel ubiquitously expressed in rat tissues, including pancreatic islets, pituitary, skeletal muscle, and heart

ATP-sensitive K+ (KATP) channels play a crucial role in coupling metabolic energy to the membrane potential of cells. We have isolated a cDNA encoding a novel member (uKATP-1) of the inward rectifier K+ channel family from a rat pancreatic islet cDNA library. Rat uKATP-1 is a 424-amino acid residue protein (M(r) = 47,960). Electrophysiological studies of uKATP-1 expressed in Xenopus laevis oocytes show that uKATP-1 is a weak rectifier and is blocked with Ba2+ ions. Single-channel patch clamp study of clonal human kidney epithelial cells (HEK293) transfected with uKATP-1 cDNA reveals that uKATP-1 closes in response to 1 mM ATP and has a single channel conductance of 70 +/- 2 picosiemens (n = 6), indicating that uKATP-1 is an ATP-sensitive inward rectifier K+ channel. In addition, uKATP-1 is activated by the KATP channel opener, diazoxide. RNA blot analysis shows that uKATP-1 mRNA is expressed ubiquitously in rat tissues, including pancreatic islets, pituitary, skeletal muscle, and heart, suggesting that uKATP-1 may play a physiological role as a link between the metabolic state and membrane K+ permeability of cells in almost every normal tissue. Since uKATP-1 shares only 43-46% amino acid identity with members of previously reported inward rectifier K+ channel subfamilies, including ROMK1, IRK1, GIRK1, and cKATP-1, uKATP-1 is not an isoform of these subfamilies and, therefore, represents a new subfamily of the inward rectifier K+ channel family having two transmembrane segments.

A new method of quantitating serum and urinary levels of 1,5-anhydroglucitol in insulin-dependent diabetes mellitus

A new method was developed for quantitating the serum and urinary levels of 1,5-anhydroglucitol (AG), a sensitive and informative marker of glycemic control. This method utilized a combination of ODS and pyranose oxidase-immobilized columns for HPLC, and monitored hydrogen peroxide production with an electrochemical detector. We applied this method to determine the serum and urinary AG levels in 15 patients with insulin-dependent diabetes mellitus (IDDM) as well as in control subjects. Baseline separation of AG from other sugars such as glucose and myoinositol was achieved. Quantitation of AG was achieved over the range from 0.2 ng to 0.3 micrograms based upon peak heights. The serum and urinary AG levels in the IDDM patients were 4.4 +/- 8.3 mg/l and 5.1 +/- 4.3 mg/day, respectively. We found that the urinary AG to serum AG ratio showed a linear correlation with the urinary glucose level in the IDDM patients (urinary glucose (y) vs. urinary AG to serum AG ratio (x): y = 9.071x-0.991; r = 0.968, P < 0.001). This method proved efficient and reliable for quantitating urinary AG. Since determination of both the AG and glucose levels in urine gives equivalent clinical information to the serum AG level, urinary monitoring could provide a valuable addition to the available methods for assessing the glycemic status of IDDM patients.

Intensification of galactosamine hepatotoxicity by polyriboinosinic acid-polyribocytidylic acid

The effects of polyriboinosinic acid-polyribocytidylic acid (poly IC) on galactosamine-induced liver cell injury in rats were studied. Treatment of rats with D-galactosamine-HC1 (400 mg/kg) increased their serum glutamate-oxaloacetate transaminase (E.C.2.6.1.1, GOT) activities, indicating that hepatocyte injury was induced by galactosamine. Rapid and intense elevations of serum GOT activities were observed when galactosamine (200 mg/kg) was administered simultaneously with poly IC (10 mg/kg) but not with poly I or poly C. Acute increase in serum GOT activities caused by the simultaneous administration of poly IC and galactosamine was prevented by the simultaneous administration of uridine (1 g/kg), which is known to inhibit the early biochemical alterations caused by the amino sugar in the hepatocyte. These findings suggest that poly IC intensifies the hepatotoxic effect of galactosamine in rats. This poly IC-induced sensitization was inhibited by pretreatment with poly IC (10 mg/kg) itself, when injected 24 hr before the administration of the hepatotoxin together with poly IC.

Association of macrophage activation with antitumor effect on rat syngeneic fibrosarcoma by Nocardia rubra cell wall skeleton

The antitumor activities of the cell wall skeleton (CWS) of Nocardia rubra were demonstrated for syngeneic fibrosarcoma (AMC-60) in ACI/N rats in regard to macrophage activation. In the 24-hr cytolytic test, activated macrophages which were fractionated from peritoneal exudate cells induced by i.p. injection of Nocardia CWS showed significant cytolytic activity for [125I]iododeoxyuridine-labeled tumor cells. Activated macrophages also strongly inhibited [3H]thymidine incorporation into the tumor cells during the 24-hr cytostatic test. When tumor cells were inoculated s.c. with activated macrophages in the Winn-type transfer assay, subsequent tumor growth was significantly inhibited. Repeated i.p. injection of the CWS seemed to enhance these antitumor activities of macrophages. The therapeutic effect of Nocardia CWS was assessed with the ascites tumor and with the solid tumor inoculated i.m. into the hind leg. In the former treatment, repeated i.p. injections completely prevented the accumulation of ascites fluid and resulted in prolongation of the survival period. The peritoneal macrophages harvested from these survivors had a strong cytolytic activity for tumor cells in the cytolytic test. In the latter treatment, repeated intratumoral injections inhibited the growth of primary tumor and prevented metastasis. Furthermore, peritoneal resident macrophages from these tumor-bearing rats treated intratumorally with the CWS were found to be cytolytic for tumor cells in the cytolytic test.