Scalable Superior Chemical Sensing Performance of Stretchable Ionotronic Skin via a π-Hole Receptor Effect

Skin-attachable gas sensors provide a next-generation wearable platform for real-time protection of human health by monitoring environmental and physiological chemicals. However, the creation of skin-like wearable gas sensors, possessing high sensitivity, selectivity, stability, and scalability (4S) simultaneously, has been a big challenge. Here, an ionotronic gas-sensing sticker (IGS) is demonstrated, implemented with free-standing polymer electrolyte (ionic thermoplastic polyurethane, i-TPU) as a sensing channel and inkjet-printed stretchable carbon nanotube electrodes, which enables the IGS to exhibit high sensitivity, selectivity, stability (against mechanical stress, humidity, and temperature), and scalable fabrication, simultaneously. The IGS demonstrates reliable sensing capability against nitrogen dioxide molecules under not only harsh mechanical stress (cyclic bending with the radius of curvature of 1 mm and cyclic straining at 50%), but also environmental conditions (thermal aging from -45 to 125 °C for 1000 cycles and humidity aging for 24 h at 85% relative humidity). Further, through systematic experiments and theoretical calculations, a π-hole receptor mechanism is proposed, which can effectively elucidate the origin of the high sensitivity (up to parts per billion level) and selectivity of the ionotronic sensing system. Consequently, this work provides a guideline for the design of ionotronic materials for the achievement of high-performance and skin-attachable gas-sensor platforms.

Enhanced Selectivity of MXene Gas Sensors through Metal Ion Intercalation: In Situ X-ray Diffraction Study

Gas molecules are known to interact with two-dimensional (2D) materials through surface adsorption where the adsorption-induced charge transfer governs the chemiresistive sensing of various gases. Recently, titanium carbide (Ti₃C₂T _x) MXene emerged as a promising sensing channel showing the highest sensitivity among 2D materials and unique gas selectivity. However, unlike conventional 2D materials, MXenes show metallic conductivity and contain interlayer water, implying that gas molecules will likely interact in a more complex way than the typical charge transfer model. Therefore, it is important to understand the role of all factors that may influence gas sensing. Here, we studied the gas-induced interlayer swelling of Ti₃C₂T _x MXene thin films and its influence on gas sensing performance. In situ X-ray diffraction was employed to simultaneously measure dynamic swelling behavior where Ti₃C₂T _x MXene films displayed selective swelling toward ethanol vapor over CO₂ gas. Results show that the controlling sodium ion concentration in the interlayers is highly important in tuning the swelling behavior and gas sensing performance. The degree of swelling matched well with the gas response intensity, and the highest gas selectivity toward ethanol vapor was achieved for Ti₃C₂T _x sensing channels treated with 0.3 mM NaOH, which also displayed the largest amount of swelling. Our results demonstrate that controlling the interlayer transport of Ti₃C₂T _x MXene is essential for enhancing the selective sensing of gas molecules.

Edge-Functionalized Graphene Nanoribbon Chemical Sensor: Comparison with Carbon Nanotube and Graphene

With growing focus on the use of carbon nanomaterials in chemical sensors, one-dimensional graphene nanoribbon (GNR) has become one of the most attractive channel materials, owing to its enhanced conductance fluctuation by quantum confinement effects and dense, abundant edge sites. Due to the narrow width of a basal plane with one-dimensional morphology, chemical modification of edge sites would greatly affect the electrical channel properties of a GNR. Here, we demonstrate for the first time that chemically functionalizing the edge sites with aminopropylsilane (APS) molecules can significantly enhance the sensing performance of the GNR sensor. The resulting APS-functionalized GNR has a sensitivity ((Δ R/ R_b)_max) of ∼30% at 0.125 ppm nitrogen dioxide (NO₂) and an ultrafast response time (∼6 s), which are, respectively, 7- and 15-fold enhancements compared to a pristine GNR sensor. This is the fastest and most sensitive gas-sensing performance of all GNR sensors reported. To demonstrate the superiority of the GNR-APS sensor, we compare its sensing performance with that of APS-functionalized carbon nanotube (CNT) and reduced graphene oxide (rGO) sensors prepared in identical synthesis conditions. Very interestingly, the GNR-APS sensor exhibited 30- and 93-fold enhanced sensitivity compared to the CNT-APS and rGO-APS sensors. This might be attributed to highly active edge sites with superior chemical reactivity, which are not present in CNT and rGO materials. Density functional theory clearly shows that the greatly enhanced gas response of GNR with edge functionalization can be attributed to the higher electron densities in the highest occupied molecular orbital levels of GNR-APS and incorporation of additional adsorption sites. This finding is the first demonstration of the importance of edge functionalization of GNR for chemical sensors.

An Ultrastable Ionic Chemiresistor Skin with an Intrinsically Stretchable Polymer Electrolyte

Ultrastable sensing characteristics of the ionic chemiresistor skin (ICS) that is designed by using an intrinsically stretchable thermoplastic polyurethane electrolyte as a volatile organic compound (VOC) sensing channel are described. The hierarchically assembled polymer electrolyte film is observed to be very uniform, transparent, and intrinsically stretchable. Systematic experimental and theoretical studies also reveal that artificial ions are evenly distributed in polyurethane matrix without microscale phase separation, which is essential for implementing high reliability of the ICS devices. The ICS displays highly sensitive and stable sensing of representative VOCs (including toluene, hexane, propanal, ethanol, and acetone) that are found in the exhaled breath of lung cancer patients. In particular, the sensor is found to be fully operational even after being subjected to long-term storage or harsh environmental conditions (relative humidity of 85% or temperature of 100 °C) or severe mechanical deformation (bending to a radius of curvature of 1 mm, or stretching strain of 100%), which can be an effective method to realize a human-adaptive and skin-attachable biosensor platform for daily use and early diagnosis.

Metallic Ti3C2Tx MXene Gas Sensors with Ultrahigh Signal-to-Noise Ratio

Achieving high sensitivity in solid-state gas sensors can allow the precise detection of chemical agents. In particular, detection of volatile organic compounds (VOCs) at the parts per billion (ppb) level is critical for the early diagnosis of diseases. To obtain high sensitivity, two requirements need to be simultaneously satisfied: (i) low electrical noise and (ii) strong signal, which existing sensor materials cannot meet. Here, we demonstrate that 2D metal carbide MXenes, which possess high metallic conductivity for low noise and a fully functionalized surface for a strong signal, greatly outperform the sensitivity of conventional semiconductor channel materials. Ti₃C₂T_x MXene gas sensors exhibited a very low limit of detection of 50-100 ppb for VOC gases at room temperature. Also, the extremely low noise led to a signal-to-noise ratio 2 orders of magnitude higher than that of other 2D materials, surpassing the best sensors known. Our results provide insight in utilizing highly functionalized metallic sensing channels for developing highly sensitive sensors.

Tunable Volatile-Organic-Compound Sensor by Using Au Nanoparticle Incorporation on MoS2

Controlling the charge concentrations of two-dimensional (2D) materials is a critical requirement for realizing versatility and potential application of these materials in high-performance electronics and sensors. In order to exploit the novel chemical-sensing characteristics of 2D materials for sensitive and selective sensors, various functionalization methods are needed to ensure efficient doping of channels based on 2D materials. In the present study, the gas-sensing performance of MoS₂ has been significantly enhanced by controlled Au nanoparticle functionalization. By using the difference in reduction potential between the Au precursor and MoS₂ work functions, MoS₂ prepared by chemical exfoliation process was decorated with nanoparticles with sizes of tens of nanometers. The n-doping effect of Au nanoparticles was observed, that is, these particles were found to have facilitated in electron charge transfer from Au to MoS₂. The controlled n-doping effect enables the tuning of the sensing of hydrocarbon-based volatile organic compounds (VOCs) and oxygen-functionalized compounds by MoS₂. A significant step has therefore been made with this study toward solving the limitations imposed by previous MoS₂-based sensors, which mostly produce a single response to various VOC analytes. This controllable chemical doping process for tuning the VOC-sensing performance of MoS₂ can eventually be used in early detection using multichannel sensing systems that have different responses and recognize patterns for target analytes.

Superior Chemical Sensing Performance of Black Phosphorus: Comparison with MoS2 and Graphene

Superior chemical sensing performance of black phosphorus (BP) is demonstrated by comparison with MoS2 and graphene. Dynamic sensing measurements of multichannel detection show that BP displays highly sensitive, selective, and fast-responsive NO2 sensing performance compared to the other representative 2D sensing materials.

The Sparing Effect of Low-Dose Esmolol on Sevoflurane during Laparoscopic Gynaecological Surgery

This double-blind, randomized, placebocontrolled study evaluated the sparing effect of esmolol on sevoflurane during laparoscopic gynaecological surgery in 54 patients between December 2009 and May 2010. The concentration of sevoflurane required to maintain adequate anaesthesia was determined. Patients received either a 0.5 mg/kg esmolol intravenous loading dose followed by infusion of 30 μg/kg per min or an identical volume of normal saline (placebo). During surgery the input concentration of sevoflurane was adjusted every 5 min to maintain systolic blood pressure within 15% of baseline and bispectral index at 50–60. Infusion of esmolol resulted in an 18.2% decrease in mean sevoflurane input concentration. Patients receiving esmolol had an earlier discharge from the postanaesthetic care unit and a lower mean fentanyl dose. In conclusion, intraoperative esmolol infusion decreased both the requirement for sevoflurane and postoperative administration of fentanyl.

The analysis of lacquer crack in the assessment of myopic choroidal neovascularization

OBJECTIVE

The aim of this study was to clarify the characteristic findings in myopic choroidal neovascularization (CNV) and the relationship with lacquer crack (LC).

METHODS

In all, 66 consecutive myopic CNV patients treated with photodynamic therapy and/or intravitreal anti-vascular endothelial growth factor injection in one eye were reviewed. Data from fluorescein angiography (FA) and indocyanine green angiography (ICGA), obtained simultaneously using the Heidelberg retina angiograph 2 (HRA2), were analyzed.

RESULTS

LCs were associated with a relatively large extent (≥3000 μm) of peripapillary choroidal atrophy and a dark rim, the proliferation of retinal pigment epithelial cells surrounding the neovascular membrane was accompanied by a small extent. Myopic CNV usually developed in the LC area surrounded by tiny crack fragments. In all, 35 patients with LCs received FA and ICGA at least twice during follow-up. LC progression was observed in nine (25.7%) treated eyes and six (23.1%) non-CNV fellow eyes. Crack fragments progressed in three distinct forms such as elongation, branching, or bridging pattern. Newly diagnosed myopic CNV was reported in 18 treated eyes and 3 fellow eyes. Progression of LCs and development of CNV occurred simultaneously in eight eyes. By multivariate Cox's regression, a statistically significant association was observed between recurrence of myopic CNV and the absence of a dark rim on ICGA.

CONCLUSIONS

The HRA2 instrument affords detailed high-resolution images of FA and ICGA. Notably, recurrence of myopic CNV developed in areas surrounded by new small crack fragments and LCs are considered to be important in the development of myopic CNV.

Axial length and intraoperative posterior vitreous detachment as predictive factors for surgical outcomes of diabetic vitrectomy

AIMS

To evaluate the relationship of axial length (AXL), intraoperatively assessed posterior vitreous detachment (PVD) status, and surgical outcomes of diabetic vitrectomy.

METHODS

Retrospective, consecutive case series. Clinical records were reviewed for 115 eyes (50 males, 65 females) with more than a 6-month follow-up who underwent diabetic vitrectomy from a single surgeon. Thirty-three eyes had vitreous haemorrhage, 37 had tractional retinal detachment (TRD) threatening the macula, 43 had TRD involving the macula, and two had neovascular glaucoma. AXL was measured preoperatively by ultrasonography, and PVD status was classified intraoperatively: broad vitreo-retinal adhesion as no PVD, PVD at the macular area with attachment at the disc as incomplete PVD, and complete PVD.

RESULTS

Forty-four eyes had no PVD, 23 had incomplete PVD, and 48 had complete PVD. A majority of the no PVD group had macula off TRD (97.7%), whereas vitreous haemorrhage (68.7%) predominated in the complete PVD group. Longer AXLs were noted in the complete PVD group compared with the no PVD and incomplete PVD groups (ANOVA in three groups P=0.0001). Univariate analysis showed that AXL had an influence on anatomical success (P=0.02). Multiple logistic regression analysis yielded that PVD status is a significant predictor of the final best corrected visual acuity (BCVA)>20/100, and BCVA>20/40 (P=0.01, P=0.02).

CONCLUSIONS

Intraoperatively assessed PVD status is a prognostic factor for functional outcomes of diabetic vitrectomy. Shorter AXL was associated with lesser PVD. In eyes with a lack of PVD, careful timing and decision of surgery are mandatory.

Objective evaluation of cataract progression associated with a high dose intravitreal triamcinolone injection

PURPOSE

To investigate the progression of cataract after a high dose (25 mg) intravitreal triamcinolone acetonide injection in patients with macular oedema secondary to diabetes and retinal vein occlusion.

METHODS

This prospective interventional case series study included 38 patients (76 eyes) with diabetic retinopathy or retinal vein occlusion diagnosed with clinical examination and fluorescein angiography. The patients were treated with 25 mg IVTA in their one eye with macular oedema and the fellow eyes served as a control. Patients were asked to return the next day and weekly for 1 month and monthly thereafter by 6 months post-operative. The progression of the cataract using photographic evaluation according to the Lens Opacities Classification System III was documented and statistical analysis was done using the Kaplan-Meier survival analysis and the log-rank test.

RESULTS

Among the 38 treated eyes, there was an increase of cataract degree by 1 grade at the end of 6 months in 10 patients. The types of progressed cataract were PSC in seven patients, cortical in six patients, and nuclear sclerosis in one patient. Six months after the injections, there was a significantly higher rate of progression of PSC (P=0.023, log-rank test) and cortical opacities (P=0.011) in the treated group while the progression of nuclear cataract was not significantly different between the treated eye and the control eye.

CONCLUSION

A high-dose (25 mg) intravitreal triamcinolone acetonide injection induces the progression of cortical and posterior subcapsular opacity in patients with diabetic macular oedema and retinal vein occlusion.

Bran extracts from pigmented rice seeds inhibit tumor promotion in lymphoblastoid B cells by phorbol ester

Using flow cytometry, we quantitatively evaluated anti-tumor-promoting activity of rice bran extracts by measuring inhibition of Epstein-Barr virus early-antigen activation (EBV-EA) induced by the tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA). This assay measures anti-tumor-promoting activity and cytotoxicity of target substances using the same batch of cells. Using this short-term procedure, we have determined the anti-tumor-promoting activity of 70% ethanol-water extracts of bran (outer layer) from seeds of five pigmented rice cultivars: Jumlalocal-1, DZ 78, Elwee, LK1-3-6-12-1-1, and LK1A-2-12-1-1. The results show that, compared to an extract from the non-pigmented white cooking rice variety Chuchung, the extracts from the pigmented varieties strongly inhibited phorbol ester-induced tumor promotion in marmoset lymphoblastoid cells B95-8 in vitro. These findings may facilitate development and use of new health-promoting rice varieties.

Role of NADP+-dependent isocitrate dehydrogenase (NADP+-ICDH) on cellular defence against oxidative injury by gamma-rays

PURPOSE

To investigate the regulation of NADPH-producing isocitrate dehydrogenase (ICDH) in cytosol (IDPc) and mitochondria (IDPm) upon gamma-ray irradiation, and the roles of IDPc and IDPm in the protection against cellular damage induced by gamma-ray irradiation.

MATERIALS AND METHODS

Changes of IDPc and IDPm proteins upon gamma-ray irradiation to NIH3T3 cells were analysed by immunoblotting. To increase or decrease the expression of IDPc or IDPm, NIH3T3 cells were stably transfected with mouse IDPc or IDPm cDNA in either the sense or the antisense direction. The transfected cells with either increased or decreased IDPc or IDPm were exposed to gamma-rays, and the levels of reactive oxygen species generation, protein oxidation and lipid peroxidation were measured.

RESULTS

Both IDPc and IDPm activities were induced by gamma-ray in NIH3T3 cells. Cells with decreased expression of IDPc or IDPm had elevated reactive oxygen species generation, lipid peroxidation and protein oxidation. Conversely, overproduction of IDPc or IDPm protein partially protected the cells from oxidative damage induced by gamma-ray irradiation.

CONCLUSIONS

The protective role of IDPc and IDPm against gamma-ray-induced cellular damage can be attributed to elevated NADPH, reducing equivalents needed for recycling reduced glutathione in the cytosol and mitochondria. Thus, a primary biological function of the ICDHs may be production of NADPH, which is a prerequisite for some cellular defence systems against oxidative damage.

Enhanced expression of transglutaminase 2 in anterior polar cataracts and its induction by TGF-beta in vitro

BACKGROUND/AIMS

Transglutaminase activity has long been implicated in the cataract formation. However, the precise mechanism of how it is produced and involved in this process remains unclear. Here the authors sought to examine whether transglutaminase 2 (TGase 2) is expressed in lens epithelial cells from patients with anterior polar cataracts, to determine whether TGase 2 expression is induced by transforming growth factor (TGF-beta) in cultured lens epithelial cells, and to determine whether TGase 2 participates in the crosslinking of fibronectin in lens epithelial cells in vitro.

METHODS

Lens epithelial cells from anterior polar cataracts, nuclear cataracts, and non-cataractous clear lenses were examined for the expression of TGase 2 using reverse transcription-polymerase chain reaction, western blot analysis, and immunohistochemical analysis. The modulation of extracellular TGase 2 activity by TGF-beta was measured by the formation of fibronectin polymers and the incorporation of fluorescein cadaverine into extracellular matrix proteins. The effect of TGase 2 overexpression was analysed by immunofluorescence staining and western blot analysis of human lens epithelial (HLE) B-3 cells transiently transfected with TGase 2 gene.

RESULTS

The expression of TGase 2 mRNA and its protein was markedly enhanced in lens epithelial cells from patients with anterior polar cataracts. Treatment of HLE B-3 cells with TGF-beta caused an increase in TGase 2 protein, its extracellular activity, and the crosslinking of fibronectin. Transient transfection of HLE B-3 cells with the TGase 2 gene led to the increased production of fibronectin monomers and polymers.

CONCLUSIONS

This study shows that TGase 2 is overexpressed in lens epithelial cells from anterior polar cataracts and that TGF-beta may be a causative factor in the induction of TGase 2. The enhanced expression of TGase 2 might cause the accumulation and crosslinking of the extracellular matrix proteins and might play a part in anterior polar cataract development.

Effects of risperidone on information processing and attention in first-episode schizophrenia

Risperidone appears to have a beneficial effect in several areas of cognitive function in schizophrenic patients. In previous studies, however, the clinical characteristics of the subjects differed between studies, and were heterogeneous even in single study. Most of the subjects were previously exposed to different kinds of neuroleptics and some of them were treatment-resistant. The aim of this study is to evaluate the effect of risperidone on attention and information processing in a homogeneous subgroup of schizophrenic patients, i.e. drug-naïve first-episode inpatients. In the patient group (n=17), cognitive tests and clinical assessments were performed before and after 8 weeks of risperidone treatment. The same cognitive tests were administered to the control group (n=24). The delay between test and retest was 8 weeks. Before treatment, the patient group performed significantly worse than control group on the tests measuring continuous attention, vigilance, and the speed of information processing. After treatment (the average dose of risperidone was 7.3mg/day), in spite of significant improvement of the clinical symptoms, the patients did not show any significant improvement or worsening in most of the items of these tests. The control group did not show any practice effect. These results suggest that first-episode schizophrenic patients have deficits in sustained attention and vigilance to visual stimuli, as well as the speed of information processing to visual and auditory stimuli, and these deficits are unrelated to clinical symptoms and remain stable during the early phase of treatment. This study did not receive pharmaceutical company financial support.

Structure-reactivity relationships in the pyridinolysis of N-methyl-N-arylcarbamoyl chlorides in dimethyl sulfoxide

Nucleophilic substitution reactions of N-methyl-N-arylcarbamoyl chlorides (YC(6)H(4)N(CH(3))COCl) with pyridines (XC(5)H(4)N) have been investigated in dimethyl sulfoxide at 45.0 degrees C. A striking trend in the selectivity parameters is that they are constant within experimental errors, rho(X) = -2.25 +/- 0.03, beta(X) = 0.42 +/- 0.01, and rho(Y) = 1.10 +/- 0.06, with changing reactivities of the electrophiles (deltasigma(Y)) and nucleophiles (deltasigma(X)), respectively, and this leads to a vanishingly small cross-interaction constant, rho(XY) approximately equals beta(XY) approximately equals 0. The rate data can be expressed in the Ritchie N(+) type equation. Based on this and other results, the mechanism of nucleophile (pyridine) addition to the resonance- stabilized carbocation is proposed. It has been shown from the definition of beta(XY) (and rho(XY)) together with the Marcus equation that the high intrinsic barrier, DeltaG(0), in the intrinsic-barrier controlled reaction series is a prerequisite for such reactions in which the cross-interaction vanishes and the N(+) relationship holds.

TGF-betas synthesized by RPE cells have autocrine activity on mesenchymal transformation and cell proliferation

The present study investigated the effects of transforming growth factor (TGF)-beta on retinal pigment epithelial (RPE) transformation in a simplified model and also whether or not TGF-beta exhibits similar proliferation effects on transformed RPE cells that it has on primary RPE cells. Furthermore, we examined the cell proliferation effects of RPE-conditioned medium (CM). A vertical wound measuring 2 mm in diameter was made on primary RPE monolayers. The expression of alpha-smooth muscle actin (SMA) by the cells located at the wound edges was observed using a confocal microscope under immunofluorescent staining. Cell proliferation was measured by incorporating 3H-thymidine into DNA. The presence of alpha-SMA was observed in the cells within the wound after treatment with TGF-beta2, while negative expression was observed in control cells. TGF-betas inhibited the proliferation of the primary cultures of RPE cells in a dose-dependent manner, but the spindle-shaped late-passaged RPE cells were not inhibited by these growth factors. The medium conditioned by RPE cells stimulated the proliferation of subconjunctival fibroblasts and inhibited the proliferation of primary RPE cells, in a manner similar to TGF-beta. These findings demonstrate that TGF-beta-stimulated RPE cells may evoke proliferative vitreoretinopathy through mesenchymal transformation and cell proliferation.

Translimbal approach for intravitreal injection in endophthalmitis after phacoemulsification

We describe a corneal limbal technique of intravitreal injection for use in cases in which it is difficult to confirm the position of the needle. Using this translimbal approach, the needle's position is easily identified and the intravitreal injection can be given using topical anesthesia. This technique is an option in eyes with a cloudy cornea or a large iridectomy.

Control of mitochondrial redox balance and cellular defense against oxidative damage by mitochondrial NADP+-dependent isocitrate dehydrogenase

Mitochondria are the major organelles that produce reactive oxygen species (ROS) and the main target of ROS-induced damage as observed in various pathological states including aging. Production of NADPH required for the regeneration of glutathione in the mitochondria is critical for scavenging mitochondrial ROS through glutathione reductase and peroxidase systems. We investigated the role of mitochondrial NADP(+)-dependent isocitrate dehydrogenase (IDPm) in controlling the mitochondrial redox balance and subsequent cellular defense against oxidative damage. We demonstrate in this report that IDPm is induced by ROS and that decreased expression of IDPm markedly elevates the ROS generation, DNA fragmentation, lipid peroxidation, and concurrent mitochondrial damage with a significant reduction in ATP level. Conversely, overproduction of IDPm protein efficiently protected the cells from ROS-induced damage. The protective role of IDPm against oxidative damage may be attributed to increased levels of a reducing equivalent, NADPH, needed for regeneration of glutathione in the mitochondria. Our results strongly indicate that IDPm is a major NADPH producer in the mitochondria and thus plays a key role in cellular defense against oxidative stress-induced damage.

Scleral fixation technique using 2 corneal tunnels for a dislocated intraocular lens

Several techniques are used to reposition dislocated intraocular lenses (IOLs). Most place a suture loop around the end of the haptic. However, in cases of a dislocated capsular bag containing the IOL, a dislocated IOL with a large haptic, or a miotic pupil, it is not easy to see the haptic ends to place the suture loop. We describe a scleral fixation technique that uses 2 corneal tunnels. A double-armed 10-0 polypropylene suture loop can be introduced through 1 corneal tunnel and placed around any accessible part of the haptic with the help of a bent 26 gauge needle. This modified technique is an easy and effective way to reposition the IOL.

Mechanism of regulation of Na+ transport by angiotensin II in primary renal cells

BACKGROUND

Angiotensin II (Ang II) has a dose-dependent, biphasic effect on the activity of the Na+/H+ antiport system in the renal proximal tubule (RPT). The aim of the present study was to further delineate the signaling pathways involved in Ang II action.

METHODS

To examine Ang II signaling, 22Na+ uptake studies were conducted with a primary rabbit RPT cell culture system. The activation of phospholipase A2 (PLA2) was assessed by measuring the release of [3H]-arachidonic acid (AA), and changes in intracellular calcium levels were determined by means of confocal microscopy.

RESULTS

Low dosages of Ang II (<10-10 mol/L) stimulated Na+ uptake, whereas high dosages of Ang II (>10-10 mol/L) inhibited Na+ uptake. Ang II (>10-10 mol/L) also caused an increase in AA release associated with an increase in intracellular calcium. Not only did exogenous AA inhibit Na+ uptake, but two PLA2 inhibitors (mepacrine and AACOCF3) blocked the Ang II-mediated inhibition of Na+ uptake. However, the cytochrome P450-dependent epoxygenase inhibitor econazole also blocked the Ang II-induced inhibition of Na+ uptake. Inhibition of Na+ uptake was obtained by the metabolic product of the epoxygenase 5,6-EET. In turn, the inhibitory effect of 5,6-EET was blocked by indomethacin.

CONCLUSIONS

The results indicate the involvement of a calcium-dependent PLA2 in mediating the inhibitory effect of Ang II on Na+ uptake. The AA, which is released following PLA2 activation, acts indirectly, through its own metabolism, via a cytochrome P450 epoxygenase pathway and ultimately cyclooxygenase itself.

Inadvertent topical exposure to isocyanates caused damage to the entire eyeball

Isocyanates are part of a group of important chemicals necessary in the production of adhesives, synthetic rubbers, and a variety of plastics. They are known to have minimal toxic effects when administered locally. However, we experienced a case of damage involving the entire eyeball in a person who accidentally exposed his eye to isocyanates. The patient presented with inflamed conjunctiva, and shrunken cornea and sclera, with focal atrophic changes in the iris. The lens and vitreous were opacified. After removal of the lens and vitreous, there were large areas of atrophic retina and areas of retinal necrosis with holes. We found that locally absorbed isocyanates can cause damage to the entire eyeball. Therefore, we recommend that if there is any evidence of isocyanate penetration, early vitrectomy should be performed to help in determining the extent of retina damage and to decrease the amount of toxic substance in the vitreous.

Effect of IOP elevation on matrix metalloproteinase-2 in rabbit anterior chamber

To investigate changes in the level of matrix metalloproteinase-2 (MMP-2) in the anterior chamber of rabbit with intraocular pressure (IOP) elevation. The IOP was elevated with scleral encircling in 12 rabbits. In the control group (4 rabbits), IOP was not changed after scleral encircling, and in group 1 (4 rabbits) and 2 (4 rabbits), IOP was elevated about 10 and 20 mmHg respectively after scleral encircling. At 2 days after scleral encircling, aqueous sampling was performed and levels of MMP-2 were checked by Western blots and gelatin zymograms. The greater the IOP elevation, the more MMP-2 expression in the anterior chamber by Western blots and gelatin zymograms. The increase in MMP-2 expression in response to IOP elevation may have important implications for the IOP feedback control mechanism.

Massive suprachoroidal hemorrhage with retinal and vitreous incarceration; a vitreoretinal surgical approach

Suprachoroidal hemorrhage(SH) may cause the expulsion of the intraocular contents. Vitreous incarceration in the wound and retinal detachment with SH are extremely poor prognostic signs. Treatment modalities depend on the severity of eye damage. This particular patient had "kissing" hemorrhagic choroidal detachment which completely filled the vitreous cavity after cataract surgery. It seemed to be inoperable. Secondary surgery was delayed 3 days to lower IOP to normal levels. The eye underwent anterior drainage sclerotomy under constantly-maintained limbal or pars plana infusion fluid line pressure. The authors performed a pars plana vitrectomy, followed by perfluorocarbon liquid injection and a silicone oil tamponade. After this surgical approach, the patient attained an attached retina and a visual acuity of 5/200 at the 3 month follow-up.

Identification and functional characterization of a novel, tissue-specific NAD(+)-dependent isocitrate dehydrogenase beta subunit isoform

To understand the interactions and functional role of each of the three mitochondrial NAD(+)-dependent isocitrate dehydrogenase (IDH) subunits (alpha, beta, and gamma), we have characterized human cDNAs encoding two beta isoforms (beta(1) and beta(2)) and the gamma subunit. Analysis of deduced amino acid sequences revealed that beta(1) and beta(2) encode 349 and 354 amino acids, respectively, and the two isoforms only differ in the most carboxyl 28 amino acids. The gamma cDNA encodes 354 amino acids and is almost identical to monkey IDHgamma. Northern analyses revealed that the smaller beta(2) transcript (1.3 kilobases) is primarily expressed in heart and skeletal muscle, whereas the larger beta(1) mRNA (1.6 kilobases) is prevalent in nonmuscle tissues. Sequence analysis of the IDHbeta gene indicates that the difference in the C-terminal 28 amino acids between beta(1) and beta(2) proteins results from alternative splicing of a single transcript. Among the various combinations of human IDH subunits co-expressed in bacteria, alphabetagamma, alphabeta, and alphagamma combinations exhibited significant amounts of IDH activity, whereas subunits produced alone and betagamma showed no detectable activity. These data suggest that the alpha is the catalytic subunit and that at least one of the other two subunits plays an essential supporting role for activity. Substitution of beta(1) with beta(2) in the co-expression system lowered the pH optimum for IDH activity from 8.0 to 7.6. This difference in optimal pH was analogous to what was observed in mouse kidney and brain (beta(1) prevalent; optimal pH 8.0) versus heart (beta(2) prevalent; pH 7.6) mitochondria. Experiments with a specially designed splicing reporter construct stably transfected into HT1080 cells indicate that acidic conditions favor a splicing pattern responsible for the muscle- and heart-specific beta(2) isoform. Taken together, these data indicate a regulatory role of IDHbeta isoforms in determining the pH optimum for IDH activity through the tissue-specific alternative splicing.

Protopanaxatriol ginsenosides inhibit glucose uptake in primary cultured rabbit renal proximal tubular cells by arachidonic acid release

Ginsenosides are involved in protective action against renal dysfunction and the regulation of renal functions. However, the effects of ginsenosides on glucose reabsorption are not yet known in renal proximal tubular cells. The aim of this study was to examine the effects of ginsenosides, protopanaxadiol (PD) saponin and protopanaxatriol (PT) saponin, on alpha-methyl-D-glucopyranoside (alpha-MG) uptake and its mechanism of action in primary cultured rabbit renal proximal tubular cells (PTCs). The alpha-MG uptake was inhibited by 90% by 0.5mM phloridizin and by removal of Na+ in the PTCs. These are typical characteristics described for the proximal tubule. To determine the time- and dose-dependent effects of PD and PT saponins on alpha-MG uptake, PTCs were incubated with different concentrations of PD and PT saponins (10-100 microg/ml) and for different time periods (from 10 min to 24 h). PT saponin (>/=50 microg/ml) from 30 min inhibited alpha-MG uptake; however, PD saponin did not alter the alpha-MG uptake at any doses and time periods. In the kinetic analysis of alpha-MG uptake, PT saponin produced a significant decrease in Vmax. The PT saponin induced inhibition of alpha-MG uptake was blocked by mepacrine, a phospholipase A2 inhibitor. In addition, PT saponin increased [3H] arachidonic acid release by 218% of that of control, and this effect was also completely blocked by mepacrine. In conclusion, PT saponin inhibited, in part, alpha-MG uptake through the phospholipase A2 signal pathway in primary cultured rabbit renal PTCs.

A signaling pathway for stimulation of Na+ uptake induced by angiotensin II in primary cultured rabbit renal proximal tubule cells

The aim of the present study was to examine the signaling pathways for a low dose of angiotensin II (ANG II) on Na+ uptake of primary cultured rabbit renal proximal tubule cells (PTCs) in hormonally defined serum-free medium. The results were as follows; ANG II (10(-11) M) stimulated the proliferation of PTCs. 10(-11) M ANG II stimulated Na+ uptake by 20%, whereas 10(-9) M ANG II inhibited it by 20% (p < 0.05). The stimulatory effect of 10(-11) M ANG II on Na+ uptake was inhibited by amiloride (10(-3) M) and by losartan (ANG II receptor subtype 1 antagonist, 10(-8) M) but not by PD123319 (ANG II receptor subtype 2 antagonist, 10(-8) M). Pertussis toxin (PTX, 50 ng/ml) prevented the ANG II-induced stimulation of Na+ uptake (p < 0.01). 8-Bromoadenosine 3', 5'-cyclic monophosphate (8-Br-cAMP, 10(-6) M) did not affect Na+ uptake. SQ 22536 (adenylate cyclase inhibitor, 10(-6) M) also did not change the ANG II-induced stimulation of Na+ uptake. ANG II did not stimulate cAMP production. In contrast, 12-O-tetradecanoylphorbol-13-acetate (TPA, 0.01 ng/ml) produced significant increase in Na+ uptake. When ANG II and TPA were added together to the PTCs, there was no additive effect on Na+ uptake. Staurosporine (calcium-dependant protein kinase C inhibitor, 10(-6) M) led to a complete inhibition of ANG II-induced stimulation of Na+ uptake. ANG II-treatment resulted in a 26% increase in total protein kinase C (PKC) activity. However, 10(-11) M ANG II did not change [Ca2+]i mobilization and [3H]-AA release while 10(-9) M ANG II increased both of them. In conclusion, the PTX-sensitive PKC pathway may be the main signaling cascade in the stimulatory effects of low dose of ANG II (10(-11) M) on Na+ uptake in the primary cultured rabbit renal proximal tubule cells in hormonally defined serum-free medium.

Radiation sensitivity of an Escherichia coli mutant lacking NADP+-dependent isocitrate dehydrogenase

Ionizing radiation induces the production of reactive oxygen species, which play an important causative role in radiation damage. NADP+-dependent isocitrate dehydrogenase (ICDH) in Escherichia coli produces NADPH, an essential reducing equivalent for the antioxidant system. The protective role of ICDH against ionizing radiation in E. coli was investigated in wild-type and ICDH-deficient strains. Upon exposure to ionizing radiation, the viability was lower and the lipid peroxidation was higher in mutant cells compared to wild-type cells. Activities of key antioxidant enzymes such as superoxide dismutase, catalase, glutathione reductase, and glucose-6-phosphate dehydrogenase were decreased by irradiation in both cells. Results suggest that ICDH plays an important role as an antioxidant enzyme in cellular defense against ionizing radiation.

Molecular mapping of the ge (s) gene controlling the super-giant embryo character in rice (Oryza sativa L.)

The giant-embryo character is useful for quality improvement in rice. Three alleles controlling embryo size have been reported at the ge locus. Based on trisomic analysis, this locus is known to reside on chromosome 7. The objective of the present study was to identify linkage between molecular markers and the ge (s) gene using an existing molecular map of rice and an F2 population derived from Hwacheongbyeo-ge (s) (super-giant embryo)/Milyang 23. The bulked-segregant method was used to screen 38 RFLPs and two microsatellite markers from rice chromosome 7. RZ395 and CDO497 flanked the ge (s) gene, at 2.4 cM and 3.4 cM, respectively. The two microsatellite markers, RM18 and RM10, were linked with ge (s) at 7.7 cM and 9.6 cM, respectively. The availability of molecular markers will facilitate selection of this grain character in a breeding program and provide the foundation for map-based gene isolation.

Molecular mapping of the ge (s) gene controlling the super-giant embryo character in rice (Oryza sativa L.)

The giant-embryo character is useful for quality improvement in rice. Three alleles controlling embryo size have been reported at the ge locus. Based on trisomic analysis, this locus is known to reside on chromosome 7. The objective of the present study was to identify linkage between molecular markers and the ge (s) gene using an existing molecular map of rice and an F2 population derived from Hwacheongbyeo-ge (s) (super-giant embryo)/Milyang 23. The bulked-segregant method was used to screen 38 RFLPs and two microsatellite markers from rice chromosome 7. RZ395 and CDO497 flanked the ge (s) gene, at 2.4 cM and 3.4 cM, respectively. The two microsatellite markers, RM18 and RM10, were linked with ge (s) at 7.7 cM and 9.6 cM, respectively. The availability of molecular markers will facilitate selection of this grain character in a breeding program and provide the foundation for map-based gene isolation.

Controlled release using a new bioerodible polyphosphazene matrix system

Polyphosphazenes possess polymer backbones consisting of nitrogen and phosphorous formally separated by alternating single and double bonds. Their potential for biomedical applications stems from the fact that polymers with a wide array of properties can be synthesized using the same starting compound, poly(dichlorophosphazene), through changes in side chain substituents, and that many of these compounds synthesized have been found to biodegrade to harmless products. In this article, studies of a novel monolithic bioerodible polyphosphazene matrix system for controlled drug delivery are presented. Poly(imidazole methylphenoxy)phosphazene is synthesized and shown to be bioerodible. The versatility of drug delivery devices fabricated using this polymer is shown through studies of release of macro-molecules and low molecular weight drugs. Initial histological evaluations of this particular polyphosphazene are also presented.