Large-scale growth of Cu2ZnSnSe4 and Cu2ZnSnSe4/Cu2ZnSnS4 core/shell nanowires

We present a fast and simple protocol for large-scale preparation of quaternary Cu(2)ZnSnSe(4) (CZTSe), as well as CZTSe/Cu(2)ZnSnS(4) (CZTS) core/shell nanowires using CuSe nanowire bundles as self-sacrificial templates. CuSe nanowire bundles were synthesized by reacting Cu(2 - x)Se nanowire bundles with sodium citrate solution. CZTSe nanowires were prepared by reacting CuSe nanowire bundles with Zn(CH(3)COO)(2) and SnCl(2) in triethylene glycol. X-ray diffraction (XRD) and selected area electron diffraction studies show that stannite CZTSe is formed. The formed CZTSe nanowire bundles have diameters of 200-400 nm and lengths of up to hundreds of micrometers. CZTSe/CZTS nanocable bundles with similar morphologies were grown by the addition of some elemental sulfur to the reaction system for growth of CZTSe bundles. The stannite CZTSe/kesterite CZTS core/shell structure of the grown nanocables was confirmed by XRD and high-resolution transmission electron microscope investigation. The influence of S/Se molar ratio in the reaction system on the crystallographic structures and optical properties of CZTSe/CZTS nanocables was studied. The obtained CZTSe/CZTS core/shell nanocable bundles show broad and enhanced optical absorption over the visible and near-infrared region, which is promising for use in photovoltaic applications.

Spin bottleneck in resonant tunneling through double quantum dots with different Zeeman splittings

We investigated the electron transport property of the InGaAs/GaAs double quantum dots, the electron g factors of which are different from each other. We found that in a magnetic field, the resonant tunneling is suppressed even if one of the Zeeman sublevels is aligned. This is because the other misaligned Zeeman sublevels limit the total current. A finite broadening of the misaligned sublevel partially relieves this bottleneck effect, and the maximum current is reached when interdot detuning is half the Zeeman energy difference.

Disruption of nNOS-PSD95 protein-protein interaction inhibits acute thermal hyperalgesia and chronic mechanical allodynia in rodents

BACKGROUND AND PURPOSE

Post-synaptic density protein 95 (PSD95) contains three PSD95/Dosophilia disc large/ZO-1 homology domains and links neuronal nitric oxide synthase (nNOS) with the N-methyl-D-aspartic acid (NMDA) receptor. This report assesses the effects of disruption of the protein-protein interaction between nNOS and PSD95 on pain sensitivity in rodent models of hyperalgesia and neuropathic pain.

EXPERIMENTAL APPROACH

We generated two molecules that interfered with the nNOS-PSD95 interaction: IC87201, a small molecule inhibitor; and tat-nNOS (residues 1-299), a cell permeable fusion protein containing the PSD95 binding domain of nNOS. We then characterized these inhibitors using in vitro and in vivo models of acute hyperalgesia and chronic allodynia, both of which are thought to require nNOS activation.

KEY RESULTS

IC87201 and tat-nNOS (1-299) inhibited the in vitro binding of nNOS with PSD95, without inhibiting nNOS catalytic activity. Both inhibitors also blocked NMDA-induced 3',5'-cyclic guanosine monophosphate (cGMP) production in primary hippocampal cultures. Intrathecal administration of either inhibitor potently reversed NMDA-induced thermal hyperalgesia in mice. At anti-hyperalgesic doses, there was no effect on acute pain thresholds or motor coordination. Intrathecal administration of IC87201 and tat-nNOS also reversed mechanical allodynia induced by chronic constriction of the sciatic nerve.

CONCLUSIONS AND IMPLICATIONS

nNOS-PSD95 interaction is important in maintaining hypersensitivity in acute and chronic pain. Disruption of the nNOS-PSD95 interaction provides a novel approach to obtain selective anti-hyperalgesic compounds.

PAUF functions in the metastasis of human pancreatic cancer cells and upregulates CXCR4 expression

Pancreatic cancer is characterized by early metastatic spread, but the process of tumor cell dissemination is largely unknown. In this study we show that the soluble protein pancreatic adenocarcinoma upregulated factor (PAUF) has an important role in the metastasis and progression of the disease. Variations in the level of PAUF, either by overexpression or knockdown, resulted in altered migration, invasion and proliferation capacity of pancreatic cancer cells. Moreover, depletion of PAUF in metastatic cells dramatically abrogated the spread of the cells to distant organs in an orthotopic xenograft mouse model. PAUF elicited the activation of the extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK) and AKT intracellular signaling cascades and consequently their downstream transcription factors in an autocrine manner. Genome-wide expression analysis revealed that C-X-C chemokine receptor type 4 (CXCR4) expression was induced by PAUF overexpression but was repressed by PAUF knockdown. The PAUF-mediated increase in cancer cell motility was attenuated by the CXCR4 inhibitor, AMD3100, or by anti-CXCR4 antibody. Furthermore, immunohistochemical analysis of pancreatic tumor tissues clearly showed a significant positive correlation between PAUF and CXCR4 expression. Collectively, these findings indicate that PAUF enhances the metastatic potential of pancreatic cancer cells, at least in part, by upregulating CXCR4 expression.

Optimal strategies for best management practice placement in a synthetic watershed

It is significant to arrange suitable design and placement of best management practices (BMPs) for reaching the aim that can not only satisfy environmental quality standards, but also decrease the total cost of BMPs. This study applied WinVAST model to predict watershed responses. The objective of this work was to discuss both the economic costs and benefits of BMPs and the control efficiency of discharge and pollutant exports, and to create some suitable standards for the optimal BMPs placement strategies. It is significant to find an optimal number and location of BMPs. In the case study herein, the number of BMPs including a detention pond and a grassy swale would be better to be given by four. The number of BMPs should also be determined by the environmental standards. Moreover, the result shows that the optimal location of BMPs placement is in the downstream area near the outlet and on the mainstream of the catchment. When the BMPs are set in these regions, it cannot only reduce the peak flow and peak pollutant exports, but also have slow time to peak watershed responses.

Observation of strong electron dephasing in highly disordered Cu93Ge4Au3 thin films

We report the observation of strong electron dephasing in a series of disordered Cu93Ge4Au3 thin films. A very short electron dephasing time possessing very weak temperature dependence around 6 K, followed by an upturn with further decrease in temperature below 4 K, is found. The upturn is progressively more pronounced in more disordered samples. Moreover, a lnT-dependent, but high-magnetic-field-insensitive, resistance rise persisting from above 10 K down to 30 mK is observed in the films. These results suggest a nonmagnetic dephasing process which is stronger than any known mechanism and may originate from the coupling of conduction electrons to dynamic defects.

Ultralong single-wall carbon nanotubes

Since the discovery of carbon nanotubes in 1991 by Iijima, there has been great interest in creating long, continuous nanotubes for applications where their properties coupled with extended lengths will enable new technology developments. For example, ultralong nanotubes can be spun into fibres that are more than an order of magnitude stronger than any current structural material, allowing revolutionary advances in lightweight, high-strength applications. Long metallic nanotubes will enable new types of micro-electromechanical systems such as micro-electric motors, and can also act as a nanoconducting cable for wiring micro-electronic devices. Here we report the synthesis of 4-cm-long individual single-wall carbon nanotubes (SWNTs) at a high growth rate of 11 microm s(-1) by catalytic chemical vapour deposition. Our results suggest the possibility of growing SWNTs continuously without any apparent length limitation.

The enhancement of nuclear receptor transcriptional activation by a mouse actin-binding protein, alpha actinin 2

The p160 coactivators, steroid receptor coactivator 1, glucocorticoid receptor interacting protein 1 (GRIP1) and the activator of thyroid and retinoic acid receptor, have two activation domains, AD1 and AD2, which transmit the activation signal from the DNA-bound nuclear receptor to the chromatin and/or transcription machinery. In screening for mammalian proteins that bind the AD2 of GRIP1, we identified a mouse actin-binding protein, alpha actinin 2 (mACTN2). mACTN2 was expressed in the heart, skeletal muscle, lung, brain and testis, but there was no expression in the spleen, liver or kidney. Interestingly, the expression level of mACTN2 in the developing embryo depended on the embryonic stage. We further demonstrated that mACTN2 could enhance two transactivation activities of GRIP1, which in turn could enhance the homodimerization of mACTN2. Importantly, mACTN2 not only served as a primary coactivator for androgen receptor, estrogen receptor and thyroid receptor activities, but also acted synergistically with GRIP1 to enhance these nuclear receptor (NR) functions. However, the NR binding motif, LXXLL, conserved in mACTN2 and other actinin family proteins, might be a dispensable domain for its coactivator roles in NRs. These findings suggested that mACTN2 might play an important role in GRIP1-induced NR coactivator functions.

Cannabinoids and pain

Cannabinoids have been used to treat pain for many centuries. However, only during the past several decades have rigorous scientific methods been applied to understand the mechanisms of cannabinoid action. Cannabinoid receptors were discovered in the late 1980s and have been found to mediate the effects of cannabinoids on the nervous system. Several endocannabinoids were subsequently identified. Many studies of cannabinoid analgesia in animals during the past century showed that cannabinoids block all types of pain studied. These effects were found to be due to the suppression of spinal and thalamic nociceptive neurons, independent of any actions on the motor systems. Spinal, supraspinal and peripheral sites of cannabinoid analgesia have been identified. Endocannabinoids are released upon electrical stimulation of the periaqueductal gray, and in response to inflammation in the extremities. These observations and others thus suggest that a natural function of cannabinoid receptors and their endogenous ligands is to regulate pain sensitivity. The therapeutic potential of cannabinoids remains an important topic for future investigations, with previous work suggesting utility in clinical studies of cancer and surgical pain. New modes of delivery and/or new compounds lacking the psychotropic properties of the standard cannabinoid ligands offer promise for cannabinoid therapeutics for pain.

Endocannabinoids in pain modulation

Five major approaches have been employed to determine the role of endocannabinoids in pain modulation: (1) studies of various markers of endocannabinoid action aimed at determining whether the necessary cannabinoid biochemical machinery is present in those brain areas that control pain sensitivity; (2) administration of exogenous cannabinoids to determine whether endocannabinoid action at appropriate sites would lead to a loss of pain sensitivity; (3) administration of compounds that would affect endocannabinoid action such as antagonists and transport inhibitors to determine whether drug-induced preterbation of cannabinoid action would alter pain sensitivity; (4) studies of genetically altered animals aimed at determining whether pain responses or responses to cannabinergic drugs are altered; and (5) studies that measure the release of endocannabinoids. Converging evidence from each of these research areas indicates that endocannabinods function to control pain in parallel with endogenous opioids but via different mechanisms.

The effects of St John's wort (Hypericum perforatum) on human cytochrome P450 activity

BACKGROUND

St John's wort (Hypericum perforatum) is a popular over-the-counter dietary supplement and herbal remedy that has been implicated in drug interactions with substrates of several cytochrome P450 (CYP) isozymes. The effect of St John's wort on CYP activity in vivo was examined with a probe drug cocktail.

METHODS

Twelve healthy subjects (5 female, 7 male) completed this 3-period, open-label, fixed schedule study. Tolbutamide (CYP2C9), caffeine (CYP1A2), dextromethorphan (CYP2D6), oral midazolam (intestinal wall and hepatic CYP3A), and intravenous midazolam (hepatic CYP3A) were administered before, with short-term St John's wort dosing (900 mg), and after 2 weeks of intake (300 mg 3 times a day) to determine CYP activities.

RESULTS

Short-term administration of St John's wort had no effect on CYP activities. Long-term St John's wort administration caused a significant (P <.05) increase in oral clearance of midazolam from 121.8 +/- 70.7 to 254.5 +/- 127.8 and a corresponding significant decline in oral bioavailability from 0.28 +/- 0.15 to 0.17 +/- 0.06. In contrast to the >50% decrease in the area under the plasma concentration-time curve (AUC) when midazolam was administered orally, long-term St John's wort administration caused a 20% decrease in AUC when midazolam was given intravenously. There was no change in CYP1A2, CYP2C9, or CYP2D6 activities as a result of St John's wort administration.

CONCLUSION

Long-term St John's wort administration resulted in a significant and selective induction of CYP3A activity in the intestinal wall. St John's wort did not alter the CYP2C9, CYP1A2, or CYP2D6 activities. Reduced therapeutic efficacy of drugs metabolized by CYP3A should be anticipated during long-term administration of St John's wort.

Bioavailability and bioequivalence: an FDA regulatory overview

Bioavailability and/or bioequivalence studies play a key role in the drug development period for both new drug products and their generic equivalents. For both, these studies are also important in the postapproval period in the presence of certain manufacturing changes. Like many regulatory studies, the assessment of bioavailability and bioequivalence can generally be achieved by considering the following three questions. What is the primary question of the study? What are the tests that can be used to address the question? What degree of confidence is needed for the test outcome? This article reviews the regulatory science of bioavailability and bioequivalence and provides FDA's recommendations for drug sponsors who intend to establish bioavailability and/or demonstrate bioequivalence for their pharmaceutical products during the developmental process or after approval.

Identification of a new class of molecules, the arachidonyl amino acids, and characterization of one member that inhibits pain

In mammals, specific lipids and amino acids serve as crucial signaling molecules. In bacteria, conjugates of lipids and amino acids (referred to as lipoamino acids) have been identified and found to possess biological activity. Here, we report that mammals also produce lipoamino acids, specifically the arachidonyl amino acids. We show that the conjugate of arachidonic acid and glycine (N-arachidonylglycine (NAGly)) is present in bovine and rat brain as well as other tissues and that it suppresses tonic inflammatory pain. The biosynthesis of NAGly and its degradation by the enzyme fatty acid amide hydrolase can be observed in rat brain tissue. In addition to NAGly, bovine brain produces at least two other arachidonyl amino acids: N-arachidonyl gamma-aminobutyric acid (NAGABA) and N-arachidonylalanine. Like NAGly, NAGABA inhibits pain. These findings open the door to the identification of other members of this new class of biomolecules, which may be integral to pain regulation and a variety of functions in mammals.

Radiation response modification following molecular inhibition of epidermal growth factor receptor signaling

The epidermal growth factor receptor (EGFR) has emerged as a central molecular target for modulation in cancer therapeutics. The correlation between overexpression of EGFR and clinically aggressive malignant disease renders EGFR a promising therapy target for many epithelial tumors, which represent approximately two thirds of all human cancers. Although the initial impetus for examining EGFR signal interruption as an anticancer strategy involved proliferative growth inhibition, more recent studies now confirm the capacity of EGFR down-regulation to modify apoptosis, invasion capacity, angiogenesis, DNA damage repair, and cellular response to radiation and selected chemotherapy agents. The favorable interaction profile for EGFR blocking agents combined with radiation and/or chemotherapy has stimulated clinical trials in diverse anatomic sites including head and neck, colorectal, pancreas, and lung. Among the most well studied and promising current agents for EGFR signal modulation are C225 and ZD1839. C225 is a chimeric monoclonal antibody to the EGFR (extracellular domain), whereas ZD1839 is a selective inhibitor of the EGFR-tyrosine kinase (cytoplasmic domain). The spectrum of cellular and biological effects that follow molecular blockade of the EGFR is enlarging and reflect the central role of this receptor in regulating epithelial cell behavior. Molecular inhibition of EGFR signaling in combination with radiation represents a highly promising investigational arena. A preview of current translational research efforts and early clinical trials focused primarily on radiation interaction is provided herein.

Minimal in vivo activation of CYP2C9-mediated flurbiprofen metabolism by dapsone

Dapsone has been shown to activate flurbiprofen 4'-hydroxylation by expressed CYP2C9 enzyme and in human liver microsomes. It has been suggested that this observation is due to substrate cooperativity on enzyme activity; however, the in vivo relevance of this observation is unknown. Thus, the purpose of this study was to evaluate whether dapsone can act cooperatively with flurbiprofen to activate the in vivo metabolism of flurbiprofen to 4'-hydroxyflurbiprofen. Twelve healthy subjects received single-dose flurbiprofen 50 mg on three occasions: alone (visit A); 2 h after a single dapsone 100-mg dose (visit B); and 2 h after the seventh daily dose of dapsone 100 mg (visit C). Concentrations of flurbiprofen and 4'-hydroxy flurbiprofen in plasma and urine and dapsone and N-acetyldapsone in plasma were determined by HPLC. Flurbiprofen pharmacokinetic parameters for the three visits were estimated by non-compartmental methods and compared in the absence and presence of dapsone. Flurbiprofen apparent oral clearance was increased by approximately 11% (P < 0.02) after dapsone 100 mg for 7 days. Dapsone plasma concentrations averaged 5 +/- 2 microM after a single dose and 11 +/- 4 microM after seven daily 100 mg doses. These dapsone plasma concentrations were within the range of concentrations producing activation of flurbiprofen metabolism by CYP2C9 in vitro. These results are consistent with the hypothesis that dapsone does influence flurbiprofen metabolism in vivo in a cooperative way to enhance metabolism. However, the magnitude of effect is substantially less than observed in vitro.

Extreme hypergastrinemia caused by atrophic gastritis and Helicobacter pylori infection--a case report

We present a case with extremely high serum gastrin induced by atrophic gastritis and Helicobacter pylori infection. The patient, a 95-year-old male, was diagnosed with idiopathic chronic diarrhea. During diagnostic work-up, his fasting serum gastrin was up to 2078 pg/mL. The secretin test was negative for gastrinoma. Octreotide scan showed no suspicious lesion except for diffuse faint uptake over the gastric antrum on the 48-hour-delay film. Gastric acidity test revealed achlorhydria. On histology examination, atrophic gastritis with Helicobacter pylori infection was found in the gastric body, but the antral mucus was normal with a slight increase in gastrin-secreting cells. To our knowledge, such extremely high serum gastrin induced by atrophic gastritis and Helicobacter pylori infection has never been reported before.

Clinical analysis and literature review of massive duodenal diverticular bleeding

A duodenal diverticulum (DD) appears in 2.5% of upper gastrointestinal (UGI) examinations and up to 22% of endoscopic retrograde cholangiopancreaticographies (ERCP) and autopsies. Most of these patients are asymptomatic, but the lesion is occasionally associated with bleeding, inflammation, perforation, obstruction of the duodenum or biliary-pancreatic duct (or both), fistula formation in the bile duct, and bezoar formation inside the diverticulum. A total of 816 patients have undergone ERCP examination at our institution since January 1987, and 100 (12.25%) of them have DD. Seven (7%) patients presented with bloody or tarry stools from massive UGI bleeding followed by shock. Only two could be diagnosed by UGI endoscopy preoperatively. The lesions were demonstrated in angiographic studies in another four cases. However, only one was correctly interpreted and one required reoperation after a correct repeat endoscopic finding. The lesions in the other two patients were identified by thorough exploration during laparotomy. The remaining case was diagnosed by intraoperative endoscopy via pyloroduodenotomy. Six underwent surgical intervention, and one was successfully treated by expectant treatment. Three (50%) had leakage from the duodenotomy but recovered uneventfully with conservative treatment. In conclusion, we believe that DD bleeding is more frequent than usually thought. A high index of suspicion should be raised in cases of UGI bleeding when more obvious and common causes have been excluded by routine endoscopy. Aggressive but careful endoscopic examination combined with accurate angiography can help us diagnose most of the cases preoperatively. Diverticulectomy is an effective surgical procedure, though it is associated with a considerable leakage rate. The morbidity is minimal if we can identify the lesion earlier and evacuate the lesion without delay.

Heat treatment of incinerator retired sorbents containing heavy metals

Previous studies have indicated that an effective control technique for heavy metal emissions from incinerators is to use solid sorbents to capture metals by physical deposition and chemical adsorption. However, the adsorbed heavy metals on the retired sorbents could possibly cause secondary pollution if they are inadequately treated. The main objective of this study is to increase the stability of four heavy metals (Cu, Pb, Cr and Cd) on retired sorbents by heat treatment. The stability was based on the toxicity characteristic leaching procedure (TCLP) tests. The parameters evaluated included: (1) different temperatures (900, 1100 and 1300 degrees C); and (2) various heating times (20, 40 and 60 min). The results indicated that most of the leaching rates decreased with increasing temperature for the four toxic heavy metals. The heat treatment time did not regularly influence the stability of heavy metals, and affected it slightly when the temperature was controlled at 1300 degrees C.

Enhancement of p53-dependent gene activation by the transcriptional coactivator Zac1

A recently discovered potential tumor suppressor protein, Zac1, was previously shown to promote cell cycle arrest and apoptosis, and to act as a positive or negative transcriptional cofactor for nuclear receptors. Since these activities are common to Zac1 and p53, we tested for a functional interaction between these two proteins by investigating possible effects of Zac1 on the transcriptional activator function of p53. Zac1 specifically enhanced the activity of p53-responsive promoters in cells expressing wild type p53. The same promoters were not activated by Zac1 in cells lacking functional p53, but the Zac1 effect was restored by co-expression of p53. Zac1 bound to p53 and enhanced the activity of p53 or its N-terminal transcriptional activation domain fused to the DNA binding domain of Gal4. These results indicate that Zac1 served as a transcriptional coactivator for p53. The enhancement of p53 activity by Zac1 was much more dramatic in HeLa cells than in other cell lines tested. HeLa cells express human papillomavirus type 18 E6 protein which inactivates and causes the degradation of p53. Physical and functional interactions observed between Zac1 and E6 protein indicated that the dramatic activity of Zac1 in HeLa cells was due not only to Zac1's coactivator effect on p53, but also to the ability of Zac1 to reverse E6 inhibition of p53.

Homocysteine thiolactone induces apoptotic DNA damage mediated by increased intracellular hydrogen peroxide and caspase 3 activation in HL-60 cells

The cytotoxicity of homocysteine derivatives on chromosomal damage in somatic cells is not well established. The present study used reactive homocysteine derivative of homocysteine thiolactone (Hcy) to investigate its causal effect on apoptotic DNA injury in human promyeloid HL-60 cells. Our results demonstrated that Hcy induced cell death and features of apoptosis including increased phosphotidylserine exposure on the membrane surface, increased apoptotic cells with hypoploid DNA contents, and internucleosomal DNA fragmentation, all of which occurred in a time- and concentration-dependent manner. Hcy treatment also significantly increased intracellular reactive oxygen species H2O2, which coincided with the elimination of caspase 3 proenzyme levels and increased caspase 3 activity at the time of the appearance of apoptotic DNA fragmentation. Preincubation of Hcy-treated HL-60 cells with catalase completely scavenged intracellular H2O2, thus inhibiting caspase 3 activity and protecting cells from apoptotic DNA damage. In contrast, superoxide dismutase failed to inhibit Hcy-induced DNA damage. Taken together, these results demonstrate that Hcy exerted its genotoxic effects on HL-60 cells through an apoptotic pathway, which is mediated by the activation of caspase 3 activity induced by an increase in intracellular hydrogen peroxide.