Time-resolved electronic phase transitions in manganites

The dynamics of first-order electronic phase transitions in complex transition metal oxides are not well understood but are crucial in understanding the emergent phenomena of electronic phase separation. We show that a manganite system reduced to the scale of its inherent electronic charge-ordered insulating and ferromagnetic metal phase domains allows for the direct observation of single electronic phase domain fluctuations within a critical regime of temperature and magnetic field at the metal-insulator transition.

Sequential therapy vs. standard triple therapies for Helicobacter pylori infection: a meta-analysis

BACKGROUND

As standard triple therapies of achieve unsatisfactory eradication of Helicobacter pylori, several alternative regimens have been proposed.

OBJECTIVES

To systematically evaluate whether sequential treatment eradicates H. pylori infection better than standard triple therapies and compare the risk of adverse events with these two regimens.

METHODS

We searched electronic databases up to February 2008 for studies evaluating the efficacy of the 10-day sequential therapy vs. standard triple regimens for eradication of H. pylori. The pooled risk ratios (RR) and 95% confidence intervals (95% CI) were calculated.

RESULTS

We identified 11 randomized trials, including eight full-text manuscripts and three abstracts. Pooled analysis demonstrated clear superiority of the sequential therapy over 7-day triple regimen with an RR of 1.23 (95% CI 1.19-1.27), and over 10-day triple regimen with a RR of 1.16 (95% CI 1.10-1.23). Adverse event rates were similar. For sequential therapy vs. 7-day triple therapies, RR = 0.96, 95% CI 0.70-1.31.

CONCLUSIONS

Sequential therapy was associated with a higher eradication rate of H. pylori compared with both 7-day triple regimen and 10-day triple regimen.

Sequential therapy vs. standard triple therapies for Helicobacter pylori infection: a meta-analysis

BACKGROUND

As standard triple therapies of achieve unsatisfactory eradication of Helicobacter pylori, several alternative regimens have been proposed.

OBJECTIVES

To systematically evaluate whether sequential treatment eradicates H. pylori infection better than standard triple therapies and compare the risk of adverse events with these two regimens.

METHODS

We searched electronic databases up to February 2008 for studies evaluating the efficacy of the 10-day sequential therapy vs. standard triple regimens for eradication of H. pylori. The pooled risk ratios (RR) and 95% confidence intervals (95% CI) were calculated.

RESULTS

We identified 11 randomized trials, including eight full-text manuscripts and three abstracts. Pooled analysis demonstrated clear superiority of the sequential therapy over 7-day triple regimen with an RR of 1.23 (95% CI 1.19-1.27), and over 10-day triple regimen with a RR of 1.16 (95% CI 1.10-1.23). Adverse event rates were similar. For sequential therapy vs. 7-day triple therapies, RR = 0.96, 95% CI 0.70-1.31.

CONCLUSIONS

Sequential therapy was associated with a higher eradication rate of H. pylori compared with both 7-day triple regimen and 10-day triple regimen.

Tunable metallicity of the La5/8Ca3/8MnO3(001) surface by an oxygen overlayer

We studied the surface structure of La_{5/8}Ca_{3/8}MnO_{3}(001) thin films using in situ scanning tunneling microscopy (STM). Atomically resolved STM images reveal that a (sqrt[2]xsqrt[2])R45;{ degrees } reconstructed surface and a (1x1) surface can be converted back and forth through adsorption and desorption of oxygen at the surface. The electrical properties of the surfaces are investigated by scanning tunneling spectroscopy. I-V curves clearly show that the presence of an oxygen overlayer renders the surface insulating while the (1x1) surface without the oxygen overlayer is metallic.

Enhanced sensitivity to group II mGlu receptor activation at corticostriatal synapses in mice lacking the familial parkinsonism-linked genes PINK1 or Parkin

An altered glutamatergic input at corticostriatal synapses has been shown in experimental models of Parkinson's disease (PD). In the present work, we analyzed the membrane and synaptic responses of striatal neurons to metabotropic glutamate (mGlu) receptor activation in two different mouse models of inherited PD, linked to mutations in PINK1 or Parkin genes. Both in PINK1 and Parkin knockout ((-/-)) mice, activation of group I mGlu receptors by 3,5-DHPG caused a membrane depolarization coupled to an increase in firing frequency in striatal cholinergic interneurons that was comparable to the response observed in the respective wild-type (WT) interneurons. The sensitivity to group II and III mGlu receptors was tested on cortically-evoked excitatory postsynaptic potentials (EPSPs) recorded from medium spiny neurons (MSNs). Both LY379268 and L-AP4, agonists for group II and III, respectively, had no effect on intrinsic membrane properties, but dose-dependently reduced the amplitude of corticostriatal EPSPs. However, both in PINK1(-/-) and Parkin(-/-) mice, LY379268, but not L-AP4, exhibited a greater potency as compared to WT in depressing EPSP amplitude. Accordingly, the dose-response curve for the response to LY379268 in both knockout mice was shifted leftward. Moreover, consistent with a presynaptic site of action, both LY379268 and L-AP4 increased the paired-pulse ratio either in PINK1(-/-) and Parkin(-/-) or in WT mice. Acute pretreatment with L-dopa did not rescue the enhanced sensitivity to LY379268. Together, these results suggest that the selective increase in sensitivity of striatal group II mGlu receptors represents an adaptive change in mice in which an altered dopamine metabolism has been documented.

Autophagic and apoptotic cell death in amniotic epithelial cells

The aim of this paper is to determine if autophagic cell death is associated with apoptosis and whether it participates in the process of term amniotic rupture. Forty pieces of fresh term amnions, including twenty from a position near the margin of the placentas and twenty from the margin of the naturally ruptured part of the placentas in term gestation were collected, respectively. The amnions were examined by scanning electron microscopy (SEM) and amniotic epithelial (AE) cells were examined by transmission electron microscopy (TEM). Autophagic and apoptotic cell death (PCD) were assayed by laser scanning confocal microscopy (LSCM) or flow cytometry using monodansylcadaverin (MDC) and propidium iodide (PI) stain. BCL(2) and BAX were examined by immunoblotting. Under SEM the amniotic epithelia appeared normal in the position near the placenta. They had an atrophied appearance in the margin of their natural broken parts. In the AE cells PCD was divided into three subtypes by TEM: autophagic cell death with positive stains of MDC and PI; apoptotic cell death; and the mixed type. Quantitative detection showed that there were more death cells, including autophagic and apoptotic, in the AE cells near the ruptured parts than near the placentas. An increased expression of BAX and a decreased expression of BCL(2) protein in the AE cells near the broken margin were observed. Apoptotic and autophagic cell death by the intrinsic pathway are the basic event in the AE cell and they are involved in the cause of membrane rupture of the human amnion in term gestation.

Solubilization and Pharmacokinetic Behaviors of Sodium Cholate/Lecithin-Mixed Micelles Containing Cyclosporine A

The purpose of this study was to investigate the solubilization capacity of sodium cholate/lecithin-mixed micelles and to evaluate the potential of mixed micelles as a carrier of cyclosporine A for intravenous infusion. The mixed micelles were prepared by coprecipitation technique. The formulation components and preparation procedures, which may affect the solubilization of cyclosporine A, were studied. The dilution stability of cyclosporine A-containing mixed micelles was investigated. Pharmacokinetic behaviors of mixed micelles in rabbits after intravenous infusion were compared with Sandimmun. Results showed the strategies to increase the solubility of cyclosporine A include lowering the molar ratio of sodium cholate to lecithin, increasing the concentration of lecithin, and reducing the ionic strength of the dispersion medium and temperature. The largest solubility was found to be 5.42 +/- 0.16 mg/ml. The leakage of mixed micelles in 5% glucose (5.84%) was much less than that in saline solution (36.7%). The relative bioavailability of mixed micelles versus Sandimmun was 112 +/- 20%, and statistical analysis demonstrated both preparations were bioequivalent. Sodium cholate/lecithin-mixed micelles are promising carriers in the intravenous delivery of cyclosporine A, considering their capability of large-scale production and low-toxic property.

Reemergent metal-insulator transitions in manganites exposed with spatial confinement

The metal-insulator transition is characterized as a single peak in the temperature-dependent resistivity measurements; exceptions to this have never been seen in any single crystal material system. We show that by reducing a single crystal manganite thin film to a wire with a width comparable to the mesoscopic phase-separated domains inherent in the material, a second and robust metal-insulator transition peak appears in the resistivity versus temperature measurement. This new observation suggests that spatial confinement is a promising route for the discovery of emergent physical phenomena in complex oxides.

Release of the medial collateral ligament to improve flexion in post-traumatic elbow stiffness

Contracture of the collateral ligaments is considered to be an important factor in post-traumatic stiffness of the elbow. We reviewed the results of isolated release of the medial collateral ligament in a series of 14 patients with post-traumatic loss of elbow flexion treated between 1998 and 2002. There were nine women and five men with a mean age of 45 years (17 to 76). They were reviewed at a mean follow-up of 25 months (9 to 48). The operation was performed through a longitudinal posteromedial incision centred over the ulnar nerve. After decompression of the ulnar nerve, release of the medial collateral ligament was done sequentially starting with the posterior bundle and the transverse component of the ligament, with measurement of the arc of movement after each step. If full flexion was not achieved the posterior half of the anterior bundle of the medial collateral ligament was released.

At the latest follow-up, the mean flexion of the elbow improved significantly from 96° (85° to 115°) pre-operatively to 130° (110° to 150°) at final follow-up (p = 0.001). The mean extension improved significantly from 43° (5° to 90°) pre-operatively to 22° (5° to 40°) at final follow-up (p = 0.003). There was a significant improvement in the functional outcome. The mean Broberg and Morrey score increased from a mean of 54 points (29.5 to 85) pre-operatively to 87 points (57 to 99) at final follow-up (p < 0.001). All the patients had normal elbow stability.

Our results indicate that partial surgical release of the medial collateral ligament is associated with improved range of movement of the elbow in patients with post-traumatic stiffness, but was less effective in controlling pain.

The mitotic checkpoint kinase NEK2A regulates kinetochore microtubule attachment stability

Loss or gain of whole chromosome, the form of chromosome instability commonly associated with cancers is thought to arise from aberrant chromosome segregation during cell division. Chromosome segregation in mitosis is orchestrated by the interaction of kinetochores with spindle microtubules. Our studies show that NEK2A is a kinetochore-associated protein kinase essential for faithful chromosome segregation. However, it was unclear how NEK2A ensures accurate chromosome segregation in mitosis. Here we show that NEK2A-mediated Hec1 (highly expressed in cancer) phosphorylation is essential for faithful kinetochore microtubule attachments in mitosis. Using phospho-specific antibody, our studies show that NEK2A phosphorylates Hec1 at Ser165 during mitosis. Although such phosphorylation is not required for assembly of Hec1 to the kinetochore, expression of non-phosphorylatable mutant Hec1(S165) perturbed chromosome congression and resulted in a dramatic increase in microtubule attachment errors, including syntelic and monotelic attachments. Our in vitro reconstitution experiment demonstrated that Hec1 binds to microtubule in low affinity and phosphorylation by NEK2A, which prevents aberrant kinetochore-microtubule connections in vivo, increases the affinity of the Ndc80 complex for microtubules in vitro. Thus, our studies illustrate a novel regulatory mechanism in which NEK2A kinase operates a faithful chromosome attachment to spindle microtubule, which prevents chromosome instability during cell division.

Sustained expression of hepatocyte nuclear factor-6 leads to loss of pancreatic beta-cells by apoptosis

Hepatocyte nuclear factor-6 (HNF-6) is the ONECUT-homeodomain transcription factor that is enriched in liver and also present in pancreas and central nervous system. It is expressed in the pancreatic bud at E10.5. In adult pancreas, its expression is restricted to the exocrine pancreas and duct cells. Since duct cells are thought to be precursors of endocrine cells and HNF-6 is involved in the regulation of the expression of HNF-4alpha and -1beta, genes that cause maturity onset diabetes of the young (MODY), we hypothesized that the sustained expression of HNF-6 would affect beta-cell function. We generated transgenic mice over-expressing human HNF-6 using the mouse insulin I promoter (MIP). We obtained one female founder in which the transgene had been incorporated into two sites; the chromosome (Ch) 14 and the X chromosome. The integration site of the latter was within centromeric heterochromatin and the transgene was inactivated. Studies on mice in which the transgene was integrated into Ch14 showed beta-cell specific defects functionally and pathologically. The insulin secretory response to glucose and arginine in the in situ-perfused pancreas was also significantly impaired in these mice. Immunohistochemical analysis revealed that the islets were smaller and had an abnormal architecture with an inverted ratio of alpha- and beta-cells resulting from beta-cell loss to 30% by 6-wk of age. The decreased number of beta-cells was quantified first time by fluorescent activated cell sorting using entire pancreata from the transgenic mice crossed with MIP-green fluorescent protein (GFP) mice. This severe loss of beta-cells involved programmed cell death.

No association of the POLI Thr706Ala polymorphism with the risk of cervical carcinoma

OBJECTIVE

To investigate the association of repair gene POLI genetic polymorphisms with cervical carcinoma.

MATERIALS AND METHODS

Four hundred sixty one cervical carcinoma patients and 628 normal women were randomly selected for this study. Single nucleotide polymorphisms (SNPs) (POLI Thr706Ala) were genotyped, and the epidemiological risk factor was assessed.

RESULTS

Compared with the POLI Thr706Thr genotype, neither POLI Thr706Ala nor POLI Ala706Ala elevated or decreased the risk of cervical carcinoma or cervical squamous cell carcinoma [ORs and 95% CIs 1.25(0.97-1.61), 1.11(0.67-1.83), 1.22(0.94-1.58), 1.06(0.63-1.78), respectively]. When analyzing the risk of the POLI Thr706Ala variant genotype for cervical carcinoma in different histological types or HPV infection status, very similar risk factors were observed for the squamous cell carcinoma group or the HPV positive group to the overall carcinoma. Regardless of sexual or reproductive histories, patients with the POLI Thr706Ala or POLI Ala706Ala genotype showed a significantly increased risk of cervical carcinoma.

CONCLUSION

The POLI Thr706Ala genotype was not associated with cervical carcinoma in a Chinese population, but we cannot exclude the possibility that the POLI polymorphism might be associated with sexual and reproductive history.

Expression of complement regulatory proteins in accommodated xenografts induced by anti-alpha-Gal IgG1 in a rat-to-mouse model

Anti-graft antibodies are often associated with graft rejection. Under special conditions, grafts continue to function normally even in the presence of anti-graft antibodies and complement. This condition is termed accommodation. We developed a xenograft accommodation model in which baby Lewis rat hearts are transplanted into Rag/GT-deficient mice, and accommodation is induced by repeated i.v. injections of low-dose anti-alpha-Gal IgG(1). The accommodated grafts survived a bolus dose of anti-alpha-Gal IgG(1), while freshly transplanted second grafts were rejected. To study the mechanism of anti-alpha-Gal IgG(1)-mediated accommodation, both real-time PCR and immunohistochemical staining revealed elevated expression of DAF, Crry and CD59 in the accommodated grafts. In vitro exposure of rat endothelial cells to anti-alpha-Gal IgG(1) also induced the up-regulation of DAF, Crry and CD59, as revealed by Western blot analyses, and was associated with an acquired resistance to antibody and complement-mediated lysis in vitro. Collectively, these studies suggest that the up-regulation of complement regulatory proteins may abrogate complement-mediated rejection and permit the development of xenograft accommodation.

A comparison of cardiovascular disease risk factor biomarkers in African Americans and Yoruba Nigerians

OBJECTIVE

Classical risk factors for coronary artery disease are changing in the developing world while rates of cardiovascular disease are increasing in these populations. Newer risk factors have been identified for cardiovascular disease, but these have been rarely examined in elderly populations and not those of developing countries.

METHODS

This study was a cross-sectional comparison from a longitudinal, observational, epidemiologic study in which participants are interviewed at three-year intervals. The sample included 1510 African Americans from Indianapolis, Indiana, and 1254 Yoruba from Ibadan, Nigeria. We compared anthropomorphic measurements; biomarkers of endothelial dysfunction (plasminogen activator inhibitor type 1 [PAI-1 and E-selectin), inflammation (C-reactive protein), and lipid oxidation (8-isoprostane); and levels of lipids, homocysteine, folate, and vitamin B12.

RESULTS

Cholesterol, triglycerides, and low-density lipoprotein cholesterol levels were higher in African Americans. For markers of endothelial dysfunction, E-selectin and homocysteine differed between men, and PAI-1 was higher in the Yoruba. C-reactive protein differed only in women, but 8-isoprostane was higher in the Yoruba.

CONCLUSION

Higher lipid levels in African Americans are consistent with their Western diet and lifestyle. Oxidative stress appears to be higher in the Yoruba than in African Americans, which may be secondary to dietary differences. Whether these differences in classical and emerging risk factors account for the different rates of cardiovascular disease, dementia, or other morbidities in these two populations remains to be determined.