Efficiency dip observed with InGaN-based multiple quantum well solar cells.

The dip of external quantum efficiency (EQE) is observed on In(0.15)Ga(0.85)N/GaN multiple quantum well (MQW) solar cells upon the increase of incident optical power density. With indium composition increased to 25%, the EQE dip becomes much less noticeable. The composition dependence of EQE dip is ascribed to the competition between radiative recombination and photocurrent generation in the active region, which are dictated by quantum-confined Stark effect (QCSE) and composition fluctuation in the MQWs.

Performance enhancement using a non-uniform vertical electric field and polymer networks for in-plane switching of multi-pretilt, vertically aligned liquid crystal devices.

A simple and reproducible alignment method for fabricating vertically aligned (VA) liquid crystal (LC) cells with a multi-pretilt structure is developed. A non-uniform vertical electric field is employed in the LC/monomer mixed cells during the photocuring process, and two pretilt domains with a functional small pretilt angle (∼1.6°) in the stabilized VA LC/polymer cells are achieved. The enhanced electro-optical performance of the cell driven by an in-plane switching field is demonstrated. Compared to the pure cell, the 2 wt.% pretilt angle cell shows 36%, 64%, and 76% improvement in the optical switch, the gray-level rise time, and the gray-level fall time responses, respectively, which are obtained at a low driving voltage (≤12 V). When applied to LC devices, the proposed method not only effectively benefits the LC molecular alignment, but it also significantly boosts the electro-optical performance.

Influence of psychological intervention on patients undergoing spinal anesthesia: a randomized trial.

OBJECTIVE: The aim of this study is to evaluate the effects of positive intervention on the anxiety and the physiological and psychological aspects among preoperative and post-surgical patients with spinal anesthesia. PATIENTS AND METHODS: A randomized trial was conducted with an intervention group (n=58) and a control group (n=59). In the intervention group, the patients were well-informed of the details during spinal anesthesia. Multiple methods were performed to control anxiety before surgery, and nurses were not allowed to discuss the condition during surgery. Anesthesiologists were invited to visit patients to avoid excessive anxiety. RESULTS: The intervention group showed lower scores of State-Trait Anxiety Inventory (STAI) (p<0.05) than the control group 24 hours post-operation. Physiological indices such as systolic blood pressure, low frequency (LF) power, high frequency (HF) power and ration of LF/HF showed better surgery recovery (p<0.05) than the control group. The length of post-anesthesia care unit stay was also significantly shortened in the intervention group (p=0.001) compared with the control group. Positive intervention may alleviate the anxiety in surgical patients receiving spinal anesthesia and improve the physiological and psychological outcomes clinically. CONCLUSIONS: Our results provide evidence indicating that proper intervention can be promoted clinically to improve the satisfaction and quality of life of patients undergoing spinal anesthesia.

Solar energy harvesting scheme using syringe-like ZnO nanorod arrays for InGaN/GaN multiple quantum well solar cells.

Syringe-like ZnO nanorod arrays (NRAs) synthesized by a hydrothermal method were applied as the light-harvesting layer on InGaN-based multiple quantum well (MQW) solar cells. Theoretical calculations show that the NRAs with an abrupt shrinkage of tip diameter can further suppress surface reflectance in comparison with the flat NRAs. InGaN-based MQW solar cells with the syringe-like NRAs exhibit greatly improved conversion efficiencies by 36%. These results are attributed to the improved flatness of the refractive index profile at the air/device interface, which results in enhanced light trapping effect on the device surface.

Transgenic expression of murine chemokine decoy receptor D6 by islets reveals the role of inflammatory CC chemokines in the development of autoimmune diabetes in NOD mice.

AIMS/HYPOTHESIS: Autoimmune diabetes results from a progressive destruction of insulin-producing beta cells in the pancreatic islets by chemokine-attracted lymphocytes. Because islet cells in NOD mice produce chemokines during the development of autoimmune diabetes, we investigated the role of inflammatory CC chemokines in disease progression in these mice. METHODS: We generated a transgenic NOD mouse model that overproduces the inflammatory CC chemokine decoy receptor D6 in pancreatic islets. RESULTS: The frequency of diabetes and insulitis scores of transgenic mice were decreased significantly, compared with non-transgenic control littermates. Transgenic expression of D6 (also known as Ccbp2) did not affect systemic lymphocyte development or alter: (1) the T cell subsets such as T helper (Th)1, Th2 and T regulatory cells; or (2) antigen-presenting cells such as dendritic cells or macrophages. The percentages and numbers of T and B lymphocytes were decreased significantly in the pancreas. Activation status, autoantigen-specific proliferation and diabetogenicity of lymphocytes were also markedly reduced. CONCLUSIONS/INTERPRETATION: Inflammatory CC chemokines play a critical role in the development of autoimmune diabetes. Transgenic expression of D6 in pancreatic islets of NOD mice reduced this pathogenic process by suppressing activation of autoreactive lymphocytes and by reducing migration of lymphocytes to the pancreas.

Transgenic expression of haem oxygenase-1 in pancreatic beta cells protects non-obese mice used as a model of diabetes from autoimmune destruction and prolongs graft survival following islet transplantation.

AIMS/HYPOTHESIS: Haem oxygenase 1 (HO-1) has strong anti-apoptotic, anti-inflammatory and antioxidative effects that help protect cells against various forms of immune attack. We investigated whether transgenic expression of Ho-1 (also known as Hmox1) in pancreatic beta cells would protect NOD mice from autoimmune damage and prolong graft survival following islet transplantation. METHODS: To evaluate the protective effect of beta cell-specific HO-1 in autoimmune diabetes, we used an insulin promoter-driven murine Ho-1 construct (pIns-mHo-1) to generate a transgenic NOD mouse. Transgene expression, insulitis and the incidence of diabetes in mice were characterised. Lymphocyte composition, the development of T helper (Th)1, Th2 and T regulatory (Treg) cells, T cell proliferation and lymphocyte-mediated disease transfer were analysed. The potential effects of transgenic islets and islet transplantation on apoptosis, inflammation and the generation of reactive oxygen species (ROS) and reactive nitrogen species (RNS) were evaluated. RESULTS: Transgenic mice showed less severe insulitis and a lower incidence of diabetes than non-transgenic control littermates. Lymphocyte composition and functions were not affected. Islets from transgenic mice expressed lower levels of proinflammatory cytokines/chemokines, proapoptotic gene expression and amounts of ROS/RNS, and were more resistant to TNF-α- and IFN-γ-induced apoptosis. Islet grafts from transgenic mice also survived longer in diabetic recipients than control islets. CONCLUSIONS/INTERPRETATION: Transgenic overexpression of Ho-1 in beta cells protected NOD mice from diabetes and delayed the autoimmune destruction of islet grafts, providing valuable insight into the development of better strategies for clinical islet transplantation in patients with type 1 diabetes.

Preoperative Evaluation of Patients with Hemifacial Spasm by Three-dimensional Time-of-Flight (3D-TOF) and Three-dimensional Constructive Interference in Steady State (3D-CISS) Sequence.

PURPOSE: The purpose of this study was to investigate and evaluate the accuracy and the preoperative diagnostic value of high-resolution magnetic resonance imaging (MRI) techniques, three-dimensional time-of-flight (3D-TOF) and three-dimensional constructive interference in steady state (3D-CISS) sequence, solely or in combination for the detection of the relationship between the facial nerve and adjacent vessels in patients with hemifacial spasm (HFS). METHODS: A total of 95 patients with primary HFS were subject to 3D-TOF and 3D-CISS MRI. The MR images were then used to evaluate the anatomical neurovascular relationships, and the results were compared with the surgical findings. We categorized the neurovascular relationship into three types: compression, contact, and neighboring or distant. Compression and/or contacts between root exit zone (REZ) and vessels were defined as positive, whereas neighboring or distant was considered to be negative. RESULTS: 3D-TOF combined with 3D-CISS assessment showed that 94 of 95 patients had artery compression or contact at REZ, whereas the remaining patient had compression at the peripheral branch of the facial nerve but not at REZ. The positive rates and the overall accuracy were 98.95 and 100 %, respectively, for the 3D-TOF combined with 3D-CISS assessment; 92.63 and 93.68 %, respectively, for the 3D-TOF assessment; and 85.26 and 86.32 %, respectively, for the 3D-CISS assessment. The positive rates and overall accuracy for the 3D-TOF combined with 3D-CISS assessment was significantly higher than those for the 3D-TOF or 3D-CISS assessment. CONCLUSIONS: Combination of 3D-TOF with 3D-CISS imaging well delineates the relationship between the facial nerve and adjacent vessels in terms of increased positive rates and accuracy.

Antenatal depiction of the fetal ear with three-dimensional ultrasonography.

OBJECTIVE: To evaluate the feasibility of examining the fetal ear with three-dimensional ultrasound. METHODS: In 125 pregnancies between 19 and 38 weeks of gestation, fetal ears were evaluated by three-dimensional ultrasound. The volume images with surface rendering were analyzed to depict the morphology, lying axis, orientation, and cranial location of the fetal ears. RESULTS: Three-dimensional images of one or both ears were successfully reconstructed in 105 fetuses. Among them, 18 fetuses had anomalous ears. The anomalous ears, including microtia, low-set ear with slope axis, abnormal ear orientation, and edematous ear, were confirmed after delivery. Three-dimensional ultrasound consistently displayed fetal ear abnormalities with greater accuracy and clarity. CONCLUSION: Because anomalous ears may be a part of complex fetal malformations, it is important to recognize ear abnormalities. Due to the complexity of the fetal ear, three-dimensional ultrasound offers more important information than two-dimensional ultrasound, which simply gives auricular geometry. We suggest that three-dimensional ultrasound can be used better to examine the fetal ear and may prove to be useful for prenatal diagnosis and genetic counseling.

Rapid photometric determination of free and esterified 3 alpha-hydroxy fecal bile acids.

A rapid, precise, and accurate photometric method for determining free and esterified fecal 3 alpha-hydroxy bile acids is described. Feces are homogenized and (a) extracted with boiling absolute ethanol, or (b) lyophilized and extracted with chloroform:methanol 2:1 (v/v). Hydrolyzed and nonhydrolyzed crude extracts are prepared and aliquots treated with a reagent containing nitro blue tetrazolium (NBT), 3 alpha-hydroxysteroid oxidoreductase, beta-nicotinamide adenine dinucleotide (beta-NAD) and diaphorase. The reagent first oxidizes bile acid 3 alpha-hydroxyls to 3-oxo groups and 3 beta-hydrogen is transferred to beta-NAD yielding beta-NADH. beta-NADH in turn reduces NBT (yellow) to its diformazan (blue). Absorbance is measured at 540 nm and is proportional to the 3 alpha-hydroxy bile acid titer of fecal extract aliquots. Fecal pigments present in crude extracts do not interfere with the assay since they absorb minimally at 540 nm.

The determination and excretion of individual human fecal bile acids.

A fluorometric method, using resazurin, for the analysis of individual fecal bile acids separated by thin layer chromatography of crude fecal extracts is described. The method is precise and accurate. The assay was used to investigate the constancy of excretion of individual fecal bile acids in small random stool samples collected over three weeks in six humans. Relatively small but significant variations were found in each case, most were random but one was progressive.

Thin-layer separation and quantification of bile acids.

A method has been developed for quantification of total free and conjugated bile acids separated on silica gel HR coated thin-layer chromatography plates. Aliquots of bile acid solutions are applied to channeled plates which are developed with either ethyl acetates: isooctane:glacial acetic acid 10:10:2 v/v for free bile acid separation, or chloroform:methanol:glacial acetic acid:water 130:50:4:8 V/V for conjugated bile acid separation. Bile acids are determined directly in serial areas of silica gel by treating gel areas suspended in tris buffer with resazurin reagent. The method is quantitative and as little as 0.1 microgram of bile acid is readily determined. Application of the method to determinations of bile acids in crude fecal extracts is described.

Portacaval shunt and measurement of canine bile acid enterohepatic circulation: effects of cholecystectomy.

Studies were made of the usefulness of serial serum bile acid determinations in dogs with end-to-side portacaval shunt for determining relative rates of bile acid enterohepatic circulation (EHC). Studies in intact and cholecystectomized dogs with shunt showed that bile acid EHC in fasting cholecystectomized animals was about three times faster than in intacts. As expected, feeding greatly increased EHC in intacts, but caused smaller but definite increases in cholecystectomized animals. Cholecystokinin (Kinevac) administration caused transient increases in intact dog bile acid EHC, but had no effect in cholecystectomized animals. These results confirm most previous studies and demonstrate that the method is sensitive and useful for comparing rates of bile acid enterohepatic circulation under different circumstances.

The hydrolysis of bile acid conjugates.

Studies were made of a) the relationship of bile acid structure and analytical recoveries (measured by 3-hydroxysteroid oxidoreductase) following vigorous alkaline hydrolysis of bile acid conjugates and b) the relationship of structure and hydrolysis time of taurine- and glycine bile acid conjugates in a reaction catalyzed by glycocholic acid hydrolase. Alkaline hydrolysis resulted in good recoveries of hydroxy and 7 and 12- oxo-bile acids but poor recoveries of 3-oxo-bile acids. Borohydride reduction of the 3-oxo-acids prevented these losses. Complete enzymatic hydrolysis of glycine conjugated bile acids was about five times more rapid than that of taurine conjugates. Hydrolysis of conjugates containing oxo groups was slow. Borohydride reduction of oxo-acids corrected this and did not inhibit enzymatic hydrolysis. It was concluded that both vigorous alkaline and enzymatic hydrolysis are satisfactory in bile acid assays if borohydride reduction is instituted before the hydrolytic step. However, due to the presence of possible enzyme inhibitors and solubility difficulties, strong alkaline hydrolysis is preferable to enzymatic hydrolysis in fecal bile acid determinations at this time.

Comparative studies of the effects of fasting on bile salt pool sizes of hamsters and rats.

Comparative studies of the effects of fasting on the total bile salt pool sizes of intact and cholecystectomized hamsters and rats were made. Rats, a species which has no gallbladder, are able to maintain the size of their total bile salt pool during 24, 48 and 72 hour fasts by an undetermined effective mechanism. Intact hamsters fasted 24, 48 and 72 hrs maintained and even increased the size of their bile salt pool. Bile salt conservation was effected by storage of the salts in the gallbladder, and to some extent, the small intestine. Cholecystectomized hamsters apparently lack any mechanism to effect bile salt conservation during fasting since their bile salt pool size decreased precipitously during 24 and 48 hr fasts.

Effects of sphincterectomy on bile acid enterohepatic circulation in dogs.

Relative rates of bile enterohepatic circulation (EHC) and bile acid pool distribution were compared in intact and sphincterectomized dogs with portacaval shunt. There was no significant difference in the rates of EHC or in the bile acid pool distribution in the groups of animals. Feeding and cholecystokinin administration caused similar increases in bile acid EHC rates in sphincterectomized and intact animals. It was concluded that the sphincter of Oddi has little or no effect on these aspects of bile acid metabolism in dogs.

Rapid analysis of human fecal bile acids.

A rapid, accurate, precise method for determining human fecal bile acids is reported. Feces are homogenized and then briefly extracted with boiling absolute ethanol. A portion of the extract is evaporated to dryness and the residue heated with mild alkali to hydrolyze bile acid 3 alpha-hydroxyl esters. Aliquots of hydrolyzed crude extract are treated with resazurin reagent which effects a series of enzyme catalyzed reactions in which bile acid free 3 alpha-hydroxyls are first oxidized to 3-oxo-groups in a reaction catalyzed by 3 alpha-hydroxysteroid dehydrogenase. Resulting protons are transferred to beta-nicotinamide adenine dinucleotide, yielding reduced beta-nicotinamide adenine dinucleotide (beta-NADH). beta-NADH then reduces nonfluorescent resazurin to fluorescent resorufin in a reaction catalyzed by diaphorase. Developed fluorescence, which is proportional to the extract aliquots bile acid content, is excited at 565 nm and read at 580 nm, wavelengths which lie in a spectral region in which there is minimal fecal pigment absorption. 3-Oxo-bile acids and bile acid 3 alpha-sulfates are extracted in the procedure but reduction and/or solvolysis is necessary before quantification.

Canine bile acid enterohepatic circulation.

The enterohepatic circulation (EHC) of bile acids has been studied in fasting dogs with portacaval shunt maintained in the steady state. In such animals the rate of EHC is proportional to systemic blood bile acid concentration. Bile acid EHC was irregular (20 to 100% variation) when measured at 15 minute or hourly intervals. Studies showed that the variations persisted in cholecystectomized and sphincterectomized animals. The irregularities were enhanced by bethanechol chloride which increases intestinal peristalsis and suppressed by diphenoxylate HCl which slows peristalsis. The variations appear to arise from irregular patterns of intestinal peristalsis. This phenomenon may explain some variations in blood bile acid concentration observed in patients with liver disease.

Prenatally detected tumor mass in the adrenal gland.

BACKGROUND/PURPOSE: Screening programs using urinary vanillylmandelic acid have detected neuroblastomas in early infancy with some success. With the widespread use of ultrasonography in modern obstetric practice, use of ultrasonography to screen for fetal neuroblastoma seems to be reasonable and practical. METHODS: Seven fetuses had suprarenal masses detected by maternal ultrasound scan at 32 to 37 weeks' gestation between 1993 and 1998. They were delivered normally if the pregnancy was uncomplicated, especially if it was without maternal preeclampsia or fetal hydrops. Each mass was further confirmed by ultrasound scan, computed tomography, or magnetic resonance imaging in the neonatal period. Tumor excision was performed at the age of 6 to 38 days of life. RESULTS: The size of the masses measured ranged from 2.0x2.0 cm to 4.5x4.5 cm. The diagnosis was adrenal hemorrhage in 1 neonate, Evan's stage I neuroblastoma in 3, and stage IV-S neuroblastoma in 3. All of the specimens with a diagnosis of neuroblastoma showed a favorable histology by the Shimada classification system. Infants with stage I disease were treated with tumor excision only, and they had survived without disease by 14, 18, and 25 months of follow-up. One infant with stage IV-S neuroblastoma was treated further with minimal chemotherapy and has survived without disease at the 66-month follow-up examination. Another child with stage IV-S neuroblastoma has survived with local recurrence and increasing liver metastasis and was still on chemotherapy at the 2-month follow-up examination. The third child with stage IV-S disease presented with massive hepatomegaly and bone marrow involvement, and disseminated intravascular coagulopathy had developed. The patient died on the 5th day of life without surgical intervention. CONCLUSIONS: The increasing use of obstetric ultrasonography has made the prenatal screening of neuroblastomas possible. The prognosis of infants with a suprarenal mass may be improved with this early detection and early surgical intervention.

Clinical experience of posterior urethral valves.

Nine patients with posterior urethral valves were seen at Chang Gung Memorial Hospital from 1985 to 1992. The age at presentation ranged from five days old to 28 years old. The presenting symptoms and signs included abdominal distension, urinary tract infection, respiratory distress, urinary ascites, and weak stream. Patients were examined by voiding cystourethrography and ultrasonography. Surgical management of these patients included primary valve ablation (three cases), cutaneous vesicostomy plus delayed valve ablation (five cases) and primary valve ablation with delayed ureteral reimplantation (one case). For small infants with posterior urethral valves (five cases), temporary vesicostomy and delayed valve ablation offers excellent results in preventing iatrogenic urethral stricture. However, for older children and young adults, the recommended treatment is primary valve ablation. For seven patients with nadir serum creatinine < 1.0 mg/dL, the renal function remained within the normal range, yet during follow-up, one case had renal insufficiency. Vesicoureteral reflux was found in five cases. Spontaneous resolution was noted in two cases after valve ablation, and three cases were controlled with prophylactic antibiotics. The experience of our series suggests that primary valve ablation may be traumatic to the neonatal urethra and temporary diversion would allow greater renal recovery during the neonatal period. With newer delicate instruments, valve ablation may be performed earlier and as a one-stage operation in the future.

[Penile revascularization: report of 4 cases].

From February to June in 1989, 4 patients consulted our ward with the complaint of impotence. After each patient's history and physical examination were taken, a series of tests were administered which included hepatic and renal function, blood sugar, cholesterol, triglyceride, testosterone, prolactin level, nocturnal penile tumescence (NPT), duplex sonography, cavernosography, and internal pudendal arteriography. The results of these tests suggested vasculogenic impotence and penile revascularization was attempted. In 2 patients the Michal-II method was used. The second patient was treated with the Virag-V method. In the fourth patient, the Michal-II method was combined with the administration of the Virag-V method. After 6 months of follow-up, objective tests such as NPT and a Duplex scanning examination showed moderate improvement in the patients who received the Virag-V method, alone or in combination with the Michal-II method. Subjectively, all the patients except the one who received just the Virag-V method, felt improvement in erection angle, penetration, and satisfaction. We conclude that penile revascularization may be a more noninvasive, physiological alternative to penile prosthesis for some cases of vasculogenic impotence.