Punctuated growth of InAs quantum dashes-in-a-well for enhanced 2-μm emission

InAs quantum dashes (Qdash) engineered to emit near 2 μm are envisioned to be promising quantum emitters for next-generation technologies in sensing and communications. In this study, we explore the effect of punctuated growth (PG) on the structure and optical properties of InP-based InAs Qdashes emitting near the 2-μm wavelength. Morphological analysis revealed that PG led to an improvement in in-plane size uniformity and increases in average height and height distribution. A 2 × boost in photoluminescence intensity was observed, which we attribute to improved lateral dimensions and structural stabilization. PG encouraged formation of taller Qdashes while photoluminescence measurements revealed a blue-shift in the peak wavelength. We proposed that the blue-shift originates from the thinner quantum well cap and decreased distance between the Qdash and InAlGaAs barrier. This study on the punctuated growth of large InAs Qdashes is a step toward realizing bright, tunable, and broadband sources for 2-μm communications, spectroscopy, and sensing.

Lack of association between ACE and bradykinin B2 receptor gene polymorphisms and ACE inhibitor-induced coughing in hypertensive Koreans

BACKGROUND & OBJECTIVE

Angiotensin converting enzyme (ACE) inhibitors are used widely in therapy for hypertension, congestive heart failure and myocardial infarction. However, coughing, one of their major adverse effects limits their use. It is documented that Asians are more liable to coughing than Europeans. The aim of this study was to investigate genetic polymorphism involved in ACE inhibitor-induced coughing.

METHODS

We monitored hypertensive subjects (n = 110) treated with ACE inhibitors, and tested for any associations between ACE inhibitor-induced coughing and polymorphisms in the genes for ACE and the bradykinin B2 receptor, which are suspected to be related to coughing.

RESULTS & DISCUSSION

We found no significant differences between the groups with coughing and without coughing in the frequency of ACE I/D (Insertion/Deletion) polymorphisms. One single nucleotide polymorphism was discovered in the promoter (-58T/C) and, one in intron-exon junction upsteam of exon 2 (-59C/A), of the bradykinin B2 receptor gene. However, no significant correlation was found between those genotypes or allele distributions and ACE inhibitor-induced coughing.

CONCLUSION

We found no significant links between polymorphisms of the ACE gene or bradykinin B2 receptor gene with ACE inhibitor-induced coughing in hypertensive Koreans. But, the topic remains controversial and requires more study.

Isoliquiritigenin inhibits cell proliferation by a heme oxygenase-dependent pathway in rat hepatic stellate cells

We evaluated whether the antiproliferative effects of isoliquiritigenin (ISL) on rat hepatic stellate cells (HSCs) are related to the induction of heme oxygenase 1 (HO-1) expression. ISL significantly inhibited serum- or growth factor-induced HSC proliferation. The inhibition of platelet-derived growth factor (PDGF)-induced proliferation by ISL was associated with the mitogen-activated protein kinase and phosphatidylinositol 3-kinase-Akt-p70 (S6K) pathways. ISL induced the expression of HO-1 in HSCs. Using the chemical inhibitor tin protoporphyrin, we also found that the inhibitory action of ISL on PDGF-induced proliferation is mediated by HO-1. These data suggest that HO-1 expression is responsible for the antiproliferative effect of ISL on HSCs.

2′,4′,6′-Tris(methoxymethoxy) chalcone attenuates hepatic stellate cell proliferation by a heme oxygenase-dependent pathway

Proliferation of hepatic stellate cells (HSCs) is central for the development of fibrosis during liver injury. We have shown previously that butein (3,4,2',4'-tetrahydroxychalcone) suppresses myofibroblastic differentiation of rat HSCs. Our aim in this study was to determine whether a new synthetic chalcone derivative, 2',4',6'-tris(methoxymethoxy) chalcone (TMMC) inhibits HSC proliferation induced by serum- or platelet-derived growth factor (PDGF). TMMC significantly inhibited growth factor-induced HSC proliferation. The inhibition of PDGF-induced proliferation by TMMC was associated with the phosphatidylinositol 3-kinase-Akt-p70(S6K) pathways. TMMC induced the expression of heme oxygenase 1 (HO-1) in HSCs. Using the chemical inhibitor tin protoporphyrin, we also found that the inhibitory action of TMMC on PDGF-induced proliferation is mediated by HO-1. Glutathione (GSH) depletion produced by TMMC activated extracellular signal-regulated kinase (ERK), which led to c-Fos expression and transactivation of activator protein 1 (AP-1) and HO-1 gene expression in the HSCs. These results demonstrate that TMMC preferentially activates ERK and that this activation leads to the transcriptional activation of AP-1 and consequently to HO-1 expression. HO-1 expression might be responsible for the antiproliferative effect of TMMC on HSCs.

The chalcone butein from Rhus verniciflua shows antifibrogenic activity

Butein is known to be the major component of the bark of Rhus verniciflua Stokes (Anacardiaceae). The aim of this work was to investigate the effects of butein on liver fibrosis induced by carbon tetrachloride (CCl4) in rats, and to explore its antifibrogenic mechanism. Butein (10 mg/kg/day or 25 mg/kg/day) showed a significant reduction of hydroxyproline and malondialdehyde levels in rats. The expression of alpha1(I) collagen and tissue inhibitor of metalloproteinase-1 (TIMP-1) mRNAs in liver was clearly reduced in a dose-dependent manner in rats given butein compared with control CCl4-treated rats. These data suggest the potential of butein to serve as an antifibrogenic agent by inhibition of collagen accumulation and lipid peroxidation, and by down-regulation of the expression of both alpha1(I) collagen and TIMP-1 mRNA.

Butein suppresses myofibroblastic differentiation of rat hepatic stellate cells in primary culture

Hepatic stellate cells play a key role in the pathogenesis of hepatic fibrosis. In this study, we investigate the inhibitory effect of butein on the activation and proliferation of rat primary cultured hepatic stellate cells. Possible cytotoxic effects were measured on stellate cells and hepatocytes using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The effects of butein on the production of collagen and smooth muscle alpha-actin proteins were examined at the same concentration, by western blot. The effects of butein on alpha1(I) collagen, tissue inhibitor of metalloproteinase-1, and metalloproteinase-13 gene expression in activated stellate cells were investigated by measuring mRNA levels using reverse transcription polymerase chain reaction. The effect of butein on DNA synthesis was also determined. Butein, at a concentration of 1 microg mL(-1), reduced DNA synthesis without affecting cell viability, and downregulated smooth muscle alpha-actin and type-I collagen expression, and alpha1(I) collagen and tissue inhibitor of metalloproteinase-1 mRNA expression, while treatment with butein induced metalloproteinase-13 mRNA expression. These findings suggest that butein is a potent inhibitor of stellate cell transformation.

Aloe emodin suppresses myofibroblastic differentiation of rat hepatic stellate cells in primary culture

We have studied the inhibitory effect of aloe emodin on hepatic stellate cells activation and proliferation, as these cells play a key role in the pathogenesis of hepatic fibrosis. Rat hepatic stellate cells were activated by contact with plastic dishes, resulting in their transformation into myofibroblast-like cells. Primary hepatic stellate cells were exposed to aloe emodin (1-10 microg/ml). Possible cytotoxic effects were measured on stellate cells and hepatocytes using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The effects of aloe emodin on production of type I collagen and smooth muscle cell alpha-actin were examined at the same concentration, by quantitative immunoprecipitation. Antiproliferative effects were examined by bromodeoxyuridine incorporation. Aloe emodin at 10 microg/ml restored the morphological changes characteristic of activated primary stellate cells, reduced DNA synthesis to 95% of control hepatic stellate cells at 10 microg/ml without affecting cell viability, and inhibited type I collagen production and smooth muscle alpha-actin expression by 86.77% and 99%, respectively, which suggest that aloe emodin is a potent inhibitor of stellate cell transformation.

Curcumin inhibits collagen synthesis and hepatic stellate cell activation in-vivo and in-vitro

We previously demonstrated that curcumin, a well-known antioxidant, inhibits collagen deposition in carbon tetrachloride-induced liver injury in rats. The major effector cells responsibleforcollagensynthesis in the liver are activated hepatic stellate cells. In this study,we investigated the inhibitory effects of curcumin on the collagen synthesis and activation of rat hepatic stellate cells in-vitro, and on hepatic stellate cell activation in-vivo. The effects of curcumin on the production of collagen and smooth muscle alpha-actin proteins and of alpha1(I) collagen mRNA were studied in-vivo and in-vitro. The effect of curcumin on DNA synthesis was also determined in-vitro. In-vivo, treatment with curcumin reduced collagen deposition and smooth muscle alpha-actin-positive areas and lowered mRNA levels of type I collagen in the liver. In-vitro, curcumin at a concentration of 5 microg mL(-1) reduced DNA synthesis, and downregulated smooth muscle alpha-actin and type I collagen expression, and alpha1(I) collagen mRNA expression. We concluded that curcumin inhibits collagen synthesis and hepatic stellate cell activation in-vivo and in-vitro, and thus may prove a valuable anti-fibrogenic agent.

The field-matching problem as it applies to the peacock three dimensional conformal system for intensity modulation

PURPOSE

Intensity modulated beam systems have been developed as a means of creating a high-dose region that closely conforms to the prescribed target volume while also providing specific sparing of organs at risk within complex treatment geometries. The slice-by-slice treatment paradigm used by one such system for delivering intensity modulated fields introduces regions of dose nonuniformity where each pair of treatment slices abut. A study was designed to evaluate whether or not the magnitude of the nonuniformity that results from this segmental delivery paradigm is significant relative to the overall dose nonuniformity present in the intensity modulation technique itself. An assessment was also made as to the increase in nonuniformity that would result if errors were made in indexing during treatment delivery.

METHODS AND MATERIALS

Treatment plans were generated to simulate correctly indexed and incorrectly indexed treatments of 4, 10, and 18 cm diameter targets. Indexing errors of from 0.1 to 2.0 mm were studied. Treatment plans were also generated for targets of the same diameter but of lengths that did not require indexing of the treatment couch.

RESULTS

The nonuniformity that results from the intensity modulation delivery paradigm is 11-16% for targets where indexing is not required. Correct indexing of the couch adds an additional 1-2% in nonuniformity. However, a couch indexing error of as little as 1 mm can increase the total nonuniformity to as much as 25%. All increases in nonuniformity from indexing are essentially independent of target diameter.

CONCLUSIONS

The dose nonuniformity introduced by the segmental strip delivery paradigm is small relative to the nonuniformity present in the intensity modulation paradigm itself. A positioning accuracy of better than 0.5 mm appears to be required when implementing segmental intensity modulated treatment plans.

Estuarine Influences on a Continental Shelf Plankton Community

On the southeastern U.S. continental shelf, phytoplankton primary production and the densities of zooplankton, fish eggs, and fish larvae peak simultaneously in late summer and early fall. Some community response to irregular storm events is observed. However, the gross plankton community dynamics on this shelf are dominated by couplings with the local estuaries and shallow nearshore zone.