Surface-plasmon-enhanced light emitters based on InGaN quantum wells

Since 1993, InGaN light-emitting diodes (LEDs) have been improved and commercialized, but these devices have not fulfilled their original promise as solid-state replacements for light bulbs as their light-emission efficiencies have been limited. Here we describe a method to enhance this efficiency through the energy transfer between quantum wells (QWs) and surface plasmons (SPs). SPs can increase the density of states and the spontaneous emission rate in the semiconductor, and lead to the enhancement of light emission by SP-QW coupling. Large enhancements of the internal quantum efficiencies (eta(int)) were measured when silver or aluminium layers were deposited 10 nm above an InGaN light-emitting layer, whereas no such enhancements were obtained from gold-coated samples. Our results indicate that the use of SPs would lead to a new class of very bright LEDs, and highly efficient solid-state light sources.

Gene silencing in DNA damage repair

Silencing of DNA repair genes plays a critical role in the development of the cancer because these genes, functioning normally, would prevent the accumulation of mutations leading to carcinogenesis. Epigenetic gene silencing is an alternative mechanism to genetic gene aberration, inactivating those genes in cancer. DNA methylation and histone modification are the major factors for epigenetic regulation of gene expression. Here, we describe recent advances in understanding of epigenetic silencing of DNA repair genes and their epigenetic mechanisms involving DNA methylation and histone modification.

Differentiation of thyroid nodules using Tl-201 scintigraphy quantitative analysis and fine-needle aspiration biopsy

We studied the differentiation of thyroid nodules using fine-needle aspiration biopsy (FNA) and Tl-201 scintigraphy quantitative analysis. One-hundred and thirty-one thyroid nodules were examined: 83 follicular lesions (58 benign and 25 malignant lesions) and 48 non-follicular lesions (8 benign and 40 malignant lesions). During Tl-201 scintigraphy examinations, an early and a delayed image were acquired 10 and 120 min after an intravenous injection, respectively. The T/N ratio (counts of nodular lesion/counts of contralateral normal thyroid tissue) of each image was calculated quantitatively. We assessed the ability of the Tl-201 scintigraphy and of the FNA analysis to differentiate benign and malignant lesions and determined the cut-off levels for the assays. For the follicular lesions, the area under the ROC (Receiver Operating Characteristic) curve (Az) for the Tl-201 scintigraphy data was greater than that for the FNA data. For the non-follicular lesions, the Az for the FNA data was greater than that for the Tl-201 scintigraphy data. We set cut-off levels at 1.370 for follicular lesions, and 1.070 for non-follicular lesions. The sensitivity and specificity were 76% and 82.7% for follicular lesions, and 90% and 87.5% for non-follicular lesions, respectively. The overall accuracy of the analysis was 84.0%.

Percutaneous sclerotherapy for venous malformations using polidocanol under fluoroscopy

This retrospective study evaluated the safety and efficacy of using polidocanol with X-ray fluoroscopy for percutaneous sclerotherapy of venous malformations of the limbs, head, and neck. The subjects were 16 of 18 patients who presented to our department with venous malformations. Two patients were excluded because they were unlikely to benefit from the treatment. Of the 16 included in the study, 1 could not be treated because of inaccessibility, and another was lost to follow-up. Among the 14 cases that we were able to follow-up, 11 cases had had pain as their primary symptom. Following treatment, this symptom remained unchanged in 1 patient, was improved in 4, and had disappeared in 6; however, there was a recurrence of pain for 3 of these patients. Two patients had sought treatment for cosmetic purposes; following treatment, the lesion disappeared in one and showed a significant reduction in the other. The remaining patient presented with a primary symptom of mouth bleeding, which disappeared following treatment. There were no critical complications. Percutaneous sclerotherapy of venous malformations using polidocanol is safe and effective, and permits repeat treatments. The efficacy is especially good for resolving pain, and complications are minor. It is desirable to use fluoroscopy for these procedures

Septicaemia and arthritis in pigs experimentally infected with Pasteurella multocida capsular serotype A

Twenty-five caesarean-derived, colostrum-deprived (CDCD) pigs and 18 specific pathogen-free pigs, aged 8 to 14 weeks, were inoculated intranasally or intratracheally with Pasteurella multocida capsular serotype A, isolated from a severe pneumonic lesion in a growing pig. The pigs were killed for necropsy on day 6 or 14 post-inoculation (PI) or, in the case of the only fatally infected animal, examined at the time of death. One CDCD pig, inoculated intratracheally with 5 ml of a bacterial suspension containing 1.7x10(9) colony-forming-units/ml, died of septicaemia on day 1 PI. Histological lesions such as severe pleuropneumonia, thrombi in glomerular capillaries, haemorrhage of the spleen, and abscesses in the tonsillar crypts were observed. The organism was recovered from a number of sites and its antigens were detected immunohistochemically in the pneumonic lesions, blood vessels of the tissues, and tonsillar crypts in the dead pig. Pneumonia, pleural adhesions and suppurative arthritis in the extremital joints were observed grossly in 3/29, 8/29 and 7/29 intratracheally inoculated pigs, respectively. In intranasally inoculated pigs, no macroscopical abnormalities were seen; histologically, however, exudative bronchopneumonia and fibrinous pleurisy were observed in 9/14 and 4/14 pigs, respectively. No significant changes were seen in the tissues of uninfected control pigs. The organism was recovered from the lesions and P. multocida type A antigen was demonstrated immunohistochemically. The organism was rarely recovered from the liver, spleen or lymph nodes (bronchopulmonary or mesenteric). The results suggest that P. multocida capsular serotype A alone can cause not only pneumonia in pigs but also septicaemia or arthritis.

Thoracic Tumors Treated with CT-guided Radiofrequency Ablation: Initial Experience

PURPOSE

To determine the effectiveness of computed tomography (CT)-guided radiofrequency (RF) ablation of malignant thoracic tumors.

MATERIALS AND METHODS

CT-guided RF ablations of 99 malignant thoracic tumors (3-80 mm in largest diameter; mean, 19.5 mm) were performed in 35 patients in 54 sessions. Ablation was performed with an RF generator by using a single internally cooled electrode. Tumors were both primary (three lesions) and secondary (pulmonary or pleural metastases, 96 lesions). Follow-up was 1-17 months (mean, 7.1 months). Follow-up CT and histopathologic examinations were evaluated. Univariate analysis was performed with the Fisher exact test, and Welch t test was used to evaluate differences between group means. P <.05 represented a significant difference. The maximal diameter of each residual tumor or local recurrence or the proportion of primary lesions of pulmonary metastatic tumors with recurrence after RF ablation were analyzed. Complications, management, and outcomes of the complications were recorded.

RESULTS

The appearance of each ablation zone, including the target tumor and surrounding normal lung parenchyma, showed involution at follow-up CT. Local recurrence was demonstrated histopathologically or radiologically in nine tumors. The other 90 tumors showed no growth progression at follow-up CT. Probable complete coagulation necrosis obtained with initial RF ablation was achieved in 91% (90 of 99) of the tumors. The mean maximal diameter of the nine tumors (19.6 mm +/- 7.7 [SD]) was not significantly different (P =.994) from that of the other 90 tumors (19.5 mm +/- 13.0). Primary lesions of those nine metastatic tumors varied and did not demonstrate a specific tendency. Complications included pneumothorax, fever higher than 37.5 degrees C, hemoptysis, cough, pleural effusion, abscess formation, and hemothorax. The overall complication rate was 76% (41 of 54 sessions).

CONCLUSION

RF ablation seems to be a promising treatment for malignant thoracic tumors.

Decrease in cortical benzodiazepine receptors in symptomatic patients with leukoaraiosis: a positron emission tomography study

BACKGROUND AND PURPOSE

[11C]flumazenil (FMZ), a ligand that selectively binds to the central benzodiazepine receptor in the neuronal membrane, is useful for evaluating neuronal viability in a positron emission tomography (PET) scan. Using this ligand, we investigated whether there was a correlation between neuronal integrity in various brain structures and dementia in patients with leukoaraiosis.

METHODS

Twelve patients with extensive leukoaraiosis on magnetic resonance imaging were divided into groups of patients with or without dementia. Based on a 2-compartment, 2-parameter model that included metabolite-corrected arterial input and PET-measured cerebral radioactivity, the distribution volume of FMZ (FMZ-V(d)) was calculated in various regions of interest by nonlinear curve fitting. Additionally, tracer kinetic analysis was applied for voxel-by-voxel quantification of FMZ-V(d), and data analysis was performed by statistical parametric mapping.

RESULTS

The presence of dementia was associated with a reduced FMZ-V(d) in widespread areas of the cerebral cortex, including the bilateral frontopolar and frontal/insular areas, the left temporo-occipital border areas, and the left marginal cortical areas.

CONCLUSIONS

Differences in neuronal integrity in the cerebral cortex might determine whether patients with leukoaraiosis become symptomatic or not.

Neurons but not glial cells show reciprocal imprinting of sense and antisense transcripts of Ube3a

The human UBE3A gene shows brain-specific partial imprinting, and lack of a maternally inherited allele causes Angelman syndrome (AS), which is characterized by neurobehavioral anomalies. In several AS model mice, imprinted Ube3a expression is detected predominantly in the hippocampus, cerebellar Purkinje cells and the olfactory bulb. Therefore, imprinting of mouse Ube3a is thought to be region-specific with different levels of silencing of the paternal Ube3a allele in different brain regions. To determine cell types of imprinted Ube3a expression, we analyzed its imprinting status in embryonic brain cells by using primary cortical cell cultures. RT-PCR and immunofluorescence were performed to determine the allelic expression of the gene. The Ube3a gene encodes two RNA transcripts in the brain, sense and antisense. The sense transcript was expressed maternally in neurons but biallelically in glial cells in the embryonic brain, whereas the antisense transcript was expressed only in neurons and only from the paternal allele. Our data present evidence of brain cell type-specific imprinting, i.e. neuron-specific imprinting of Ube3a in primary brain cell cultures. Reciprocal imprinting of sense and antisense transcripts present only in neurons suggests that the neuron-specific imprinting mechanism is related to the lineage determination of neural stem cells.

CpG methylation of MGMT and hMLH1 promoter in hepatocellular carcinoma associated with hepatitis viral infection

Inactivations of DNA repair genes, O(6)-methylguanine-DNA methyltransferase (MGMT) and hMLH1, by promoter hypermethylation have been reported in several types of primary human neoplasia. This epigenetic inactivation mechanism remains elusive in hepatocellular carcinoma (HCC). To investigate the relation between the expression of MGMT and hMLH1 and the CpG methylation within their promoters in HCCs with or without hepatitis viral infection, we performed immunohistochemistry and urea/bisulphite sequencing on 46 HCCs, corresponding noncancerous tissues, and 20 normal liver tissues. MGMT- and hMLH1-negative HCCs were 60.9% (28 out of 46) and 21.8% (10 out of 46), respectively. HCCs lacking both proteins were 10.9% (five out of 46). The frequency and extent of CpG methylation in the MGMT promoter increased along with hepatitis viral infection and pathological progression. MGMT-negative tumours showed very frequent and widespread methylation in the promoter compared with MGMT-positive tumours. Half of the hMLH1-negative HCCs showed promoter hypermethylation. These data suggested that MGMT gene silencing in a subset of HCCs was likely caused by epigenetic alteration, such as promoter hypermethylation, and that the promoter hypermethylation silenced the hMLH1 gene in half of the hMLH1-negative tumours. A correlation between the promoter methylation status and viral infection, although it was weak, intimated that hepatitis viral infections could play a role in the CpG methylation of the MGMT promoter.

Effect of non-aqueous phase liquid on biodegradation of PAHs in spilled oil on tidal flat

Biodegradation rates of polycyclic aromatic hydrocarbons (PAHs) in spilled oil stranded on tidal flats were studied using model reactors to clarify the effects of NAPL on the biodegradation of PAHs in stranded oil on tidal flat with special emphasis on the relationship between dissolution rates of PAHs into water and viscosity of NAPL. Biodegradation of PAHs in NAPL was limited by the dissolution rates of PAHs into water. Biodegradation rate of chrysene was smaller than that for acenaphthene and phenanthrene due to the smaller dissolution rates. Dissolution rates of PAHs in fuel oil C were smaller those in crude oil due to high viscosity of fuel oil C. Therefore, biodegradation rates of PAHs in fuel oil C were smaller than those in crude oil. Biodegradation rates of PAHs in NAPL with slow decrease rate like fuel oil C were slower than those in NAPL with rapid decrease like crude oil. The smaller decrease rate of fuel oil C than crude oil was due to higher viscosity of fuel oil C. Therefore, not only the dissolution rate of PAHs but also the decrease rates of NAPL were important factors for the biodegradation of PAHs.

Clinical and pathologic characteristics of nontyphoidal salmonella encephalopathy

OBJECTIVE

To investigate the clinical and pathologic characteristics of primary encephalopathy caused by nontyphoidal salmonellosis (NTS).

METHODS

Case records of six Japanese hospitals from 1994 to 1999 were reviewed. Eight cases of primary NTS encephalopathy were identified based on strictly defined criteria: 1) encephalopathic feature defined as altered state of consciousness, altered cognition or personality, or seizures; 2) detection of nontyphoidal Salmonella species in stool; 3) absence of other viral or bacterial infection associated with CNS abnormalities; and 4) absence of alternative explanation by underlying neurologic or systemic disease. Three patients died, three had severe sequelae, and two recovered completely. The authors analyzed their clinical course, neurologic symptoms, and histopathologic findings.

RESULTS

NTS encephalopathy was clinically characterized by diffuse and rapidly progressive brain dysfunction and circulatory failure that developed following enteritis. There was no evidence of severe dehydration or sepsis, and encephalopathy was rarely accompanied by abnormal laboratory data, except elevated CSF opening pressure, brain edema on CT, and slow waves on EEG. Pathologic findings included minimal ischemic damage and mild edema in the brain, microvesicular fatty change of the liver, severe enterocolitis but no evidence of dehydration, and no fatal organ damage including microvasculature and endothelial cells.

CONCLUSION

Noninfectious encephalopathy associated with nontyphoidal salmonella infection is a distinctive clinical entity that can be differentiated from Reye's syndrome and Ekiri.

A mandatory role for STAT4 in IL-12 induction of mouse T cell CCR5

IL-12 was recently shown to induce CCR5 on TCR-triggered mouse T cells. Considering that STAT4 is the most critical of IL-12 signaling molecules, this study investigated the role for STAT4 in the induction of CCR5 expression. IL-12R was induced by stimulation with anti-CD3 plus anti-CD28 mAb similarly on T cells from wild-type (WT) and STAT4-deficient (STAT4(-/-)) mice, but the levels of IL-12R induced on IFN-gamma-deficient (IFN-gamma(-/-)) T cells were lower compared with WT T cells. Exposure of TCR-triggered WT T cells to IL-12 induced CCR5 expression. In contrast, TCR-triggered STAT4(-/-) T cells failed to express CCR5 in response to IL-12. IL-12 stimulation induced detectable albeit reduced levels of CCR5 expression on IFN-gamma(-/-) T cells. Addition of rIFN-gamma to cultures of IFN-gamma(-/-) T cells, particularly to cultures during TCR triggering resulted in restoration of CCR5 expression. However, CCR5 expression was not induced in STAT4(-/-) T cells by supplementation of rIFN-gamma. These results indicate that for the induction of CCR5 on T cells, 1) STAT4 plays an indispensable role; 2) such a role is not substituted by simply supplementing rIFN-gamma; and 3) IFN-gamma amplifies CCR5 induction depending on the presence of STAT4.

Ocular absorption behavior of palmitoyl tilisolol, an amphiphilic prodrug of tilisolol, for ocular drug delivery

The objective of this study was to examine the ocular absorption behavior of an amphiphilic prodrug after instillation onto the cornea of rabbits. A micellar solution of O-palmitoyl tilisolol (PalTL), an amphiphilic prodrug, was prepared. After instillation of tilisolol (TL) and PalTL, the drug concentrations in the tear fluid, cornea, aqueous humor, iris-ciliary body, vitreous body, and blood were measured. In addition, in situ ocular absorption behavior was also evaluated. After instillation of TL, the concentration of TL in the tear fluid quickly decreased. After instillation of PalTL, prolonged retention and high concentrations of PalTL in tear fluid and the cornea were observed. In addition, more prolonged retention of the TL concentration after instillation of PalTL than after instillation of TL was observed in the cornea, aqueous humor, and iris-ciliary body. In situ experiments demonstrated that PalTL was mainly absorbed by the corneal route and the improvement effects of PalTL under in vivo conditions was due to an enhanced transit time of PalTL in ocular tissues. PalTL, an amphiphilic prodrug, exhibited increased retention in the precorneal area compared with the parent drug, TL, resulted in improved ocular absorption of the parent drug.