Biomimetic coating of magnesium alloy for enhanced corrosion resistance and calcium phosphate deposition

Degradable metals have been suggested as biomaterials with revolutionary potential for bone-related therapies. Of these candidate metals, magnesium alloys appear to be particularly attractive candidates because of their non-toxicity and outstanding mechanical properties. Despite their having been widely studied as orthopedic implants for bone replacement/regeneration, their undesirably rapid corrosion rate under physiological conditions has limited their actual clinical application. This study reports the use of a novel biomimetic peptide coating for Mg alloys to improve the alloy corrosion resistance. A 3DSS biomimetic peptide is designed based on the highly acidic, bioactive bone and dentin extracellular matrix protein, phosphophoryn. Surface characterization techniques (scanning electron microscopy, energy dispersive X-ray spectroscopy and diffuse-reflectance infrared spectroscopy) confirmed the feasibility of coating the biomimetic 3DSS peptide onto Mg alloy AZ31B. The 3DSS peptide was also used as a template for calcium phosphate deposition on the surface of the alloy. The 3DSS biomimetic peptide coating presented a protective role of AZ31B in both hydrogen evolution and electrochemical corrosion tests.

Molecular characterization of the pseudorabies virus UL2 gene

A 948-bp sequence of the UL2 gene was amplified from the pseudorabies virus (PRV) Becker strain genome using polymerase chain reaction, and the gene identity was confirmed through further cloning and sequencing. Bioinformatic analysis indicated that the PRV UL2 gene encodes a putative polypeptide with 315-amino acid residues. Its encoding protein, designated UL2, has a conserved uracil-DNA glycosylase (UDG)_F1 domain, which is closely related to the herpesvirus UDG family and is highly conserved among its counterparts encoded by UDG genes. Multiple nucleic acid and amino acid sequence alignments suggested that the product of PRV UL2 has a relatively higher homology with UL2-like proteins of Alphaherpesvirinae than that of other subfamilies of Herpesviridae. In addition, phylogenetic analysis showed that PRV UL2 had a close evolutionary relationship with members of Alphaherpesvirinae, especially members of the genus Varicellovirus of bovine herpesvirus 1 and bovine herpesvirus 5. Antigen prediction indicated the presence of several potential B-cell epitopes in PRV UL2. In addition, secondary structure and 3-dimensional structure prediction revealed that PRV UL2 consisted predominantly of an α-helix. Taken together, these results provide molecular biological insight for the further study of the function and mechanism of UL2 during PRV infection.

People who live in a cold climate: thermal adaptation differences based on availability of heating

Are there differences in thermal adaptation to cold indoor environments between people who are used to living in heating and non-heating regions in China? To answer this question, we measured thermal perceptions and physiological responses of young men from Beijing (where there are indoor space heating facilities in winter) and Shanghai (where there are not indoor space heating facilities in winter) during exposures to cold. Subjects were exposed to 12°C, 14°C, 16°C, 18°C, 20°C for 1 h. Subjects from Beijing complained of greater cold discomfort and demonstrated poorer physiological acclimatization to cold indoor environments than those from Shanghai. These findings indicate that people's chronic indoor thermal experience might be an important determinant of thermal adaptation.

Iptakalim ameliorates monocrotaline-induced pulmonary arterial hypertension in rats

OBJECTIVES

We sought to investigate the experimental therapeutic effects and mechanisms of iptakalim, a new adenosine triphosphate (ATP)-sensitive potassium channel (K(ATP)) opener, on monocrotaline (MCT)-induced pulmonary arterial hypertension (PAH) and right heart ventricle remodeling in rats.

METHODS

Rats were injected with a single dose (50 mg/kg, ip) of MCT and given iptakalim (1, 3, and 9 mg/kg·per d, orally [po]) or saline for 28 days. The hemodynamic and morphometric parameters were assessed. Tissue and plasma samples were collected for histological and molecular analysis.

RESULTS

Treatment with iptakalim at daily oral doses of 1, 3, and 9 mg/kg from the day of MCT injection attenuated the high right ventricle systolic pressure (RVSP) and the increased weight ratio of right ventricle (RV) to left ventricle (LV) plus septum (S) (RV/(LV+S)), decreased heart rate (HR) and decreased mean arterial pressure (MAP), inhibited the RV myocardial tissue cell apoptosis, and the RV myocardial cell B-type natriuretic peptide (BNP) protein expression. Iptakalim also decreased the serum levels of nitric oxide (NO), endothelin 1 (ET-1), BNP, and the levels of NO, ET-1, and tumor necrosis factor-alpha (TNF-α) in the lung tissue.

CONCLUSION

These results indicate that iptakalim prevents MCT-induced PAH and RV remodeling and its mechanisms are related to inhibiting the pathological increases in NO, ET-1, BNP, and TNF-α, and Iptakalim may be a promising candidate for the treatment of PAH.

Perceived parenting and risk for major depression in Chinese women

BACKGROUND

In Western countries, a history of major depression (MD) is associated with reports of received parenting that is low in warmth and caring and high in control and authoritarianism. Does a similar pattern exist in women in China?

METHOD

Received parenting was assessed by a shortened version of the Parental Bonding Instrument (PBI) in two groups of Han Chinese women: 1970 clinically ascertained cases with recurrent MD and 2597 matched controls. MD was assessed at personal interview.

RESULTS

Factor analysis of the PBI revealed three factors for both mothers and fathers: warmth, protectiveness, and authoritarianism. Lower warmth and protectiveness and higher authoritarianism from both mother and father were significantly associated with risk for recurrent MD. Parental warmth was positively correlated with parental protectiveness and negatively correlated with parental authoritarianism. When examined together, paternal warmth was more strongly associated with lowered risk for MD than maternal warmth. Furthermore, paternal protectiveness was negatively and maternal protectiveness positively associated with risk for MD.

CONCLUSIONS

Although the structure of received parenting is very similar in China and Western countries, the association with MD is not. High parental protectiveness is generally pathogenic in Western countries but protective in China, especially when received from the father. Our results suggest that cultural factors impact on patterns of parenting and their association with MD.

Recent advances in the field of 16-membered macrolide antibiotics

The continuing emergence of bacterial resistance has provided an incentive for recent intensified research on macrolide antibiotics. Belonging to the macrolide family, 16-membered macrolides also experience a renewed interest in further exploration. The medicinal potential of 16-membered macrolides in search for new antibacterials stems from some advantages over 14-membered macrolides, such as gastrointestinal tolerability, structural flexibility, and lack of inducible resistance. Thus, compared with abundant articles on various 14-membered macrolide derivatives in the literature, this review will highlight some representative 16-membered macrolide antibiotics and their recently discovered analogs. Furthermore, the action and resistance mechanisms of 16-membered macrolide antibiotics will be elucidated as well to assist the drug design.

A comparison of the thermal adaptability of people accustomed to air-conditioned environments and naturally ventilated environments

It has been reported previously that people who are acclimated to naturally ventilated (NV) environments respond to hot and warm environments differently than people who are acclimated to air-conditioned (AC) environments. However, it is not clear whether physiological acclimatization contributes to this discrepancy. To study whether living and working in NV or AC environments for long periods of time can lead to different types of physiological acclimatization, and whether physiological acclimatization has an important influence on people's responses of thermal comfort, measurements of physiological reactions (including skin temperature, sweat rate, heart rate variability, and heat stress protein 70) and thermal comfort responses were conducted in a 'heat shock' environment (climate chamber) with 20 people (10 in the NV group and 10 in the AC group). The results showed that the NV group had a significantly stronger capacity for physiological regulation to the heat shock than the AC group. In other words, the NV group did not feel as hot and uncomfortable as the AC group did. These results strongly indicate that living and working in indoor thermal environments for long periods of time affects people's physiological acclimatization. Also, it appears that long-term exposure to stable AC environments may weaken people's thermal adaptability.

PRACTICAL IMPLICATIONS

This study examined the psychological and physiological differences of thermal adaptability of people used to air-conditioned environments and naturally ventilated environments. The results suggested that long-term exposure to stable air-conditioned environments may weaken people's thermal adaptability. Therefore, it might be advantageous for people to spend less time in static air-conditioned environments; this is not only because of its possible deleterious impact on people's physiological adaptability, but also because the air-conditioners' high-energy consumption will contribute to the effects of global warming.

Liver X receptor activation attenuates inflammatory response and protects cholinergic neurons in APP/PS1 transgenic mice

Alzheimer's disease (AD) is associated with beta-amyloid deposition, glial activation, and increased levels of the cytokines, as well as cholinergic dysfunction. Liver X receptor (LXR) has been found to inhibit the expression of pro-inflammatory genes. However, the effects of LXR activation on inflammatory response and on cholinergic system in AD are not yet clear. The present results revealed that LXR activation markedly attenuated several inflammatory markers and decreased microglial activation and reactive astrocytes in amyloid precursor protein (APP)/PS1 transgenic mice. Additionally, LXR activation significantly increased the number of cholinergic neurons in the medial septal regions and the basal nucleus of Meynert (NBM), and attenuated cognitive impairment. Furthermore, we observed that LXR activation inhibited the production of COX-2 and iNOS from Aβ(25-35)-induced microglia. LXR activation and nuclear factor kappa B (NF-κB) inhibitor PDTC both attenuated Aβ(25-35) induction of NF-κB activation. These results suggest that LXR agonists suppress the production of pro-inflammatory molecules, at least in part, by modulating NF-κB-signaling pathway. Collectively, these studies suggest that LXR agonists may have therapeutic significance in AD.

Mutational analysis of the Kir6.1 gene in Chinese hypertensive patients treated with the novel ATP-sensitive potassium channel opener iptakalim

Iptakalim is a novel K(ATP) opener with antihypertensive properties. The Kir6.1 gene is one of the candidate genes that may influence the response to iptakalim in hypertensive patients. We aimed to ascertain whether a mutation in the coding region of the Kir6.1 gene is present in Chinese Han hypertensive patients. The study population included 162 Chinese Han hypertensive patients (81 men and 81 women with a mean age of 55±9 years). Mutational analysis of the coding region of Kir6.1 was performed using PCR-SSCP and direct sequencing. No missense or nonsense mutations were found in these samples, while a single base pair substitution (C to T) at nucleotide position 111 in exon 2 of the coding region was noted in four patients (one female and three male), who were all heterozygous for the mutation. This C to T substitution did not result in an amino acid substitution (Ile37Ile, silent mutation). In the remaining 158 patients, no mutation was detected. The blood pressure of these four patients carrying the I37I polymorphism was well controlled by iptakalim. No mutation that alters the primary structure of Kir6.1 was detected in Chinese Han hypertensive patients. The results indicate that abnormality in the primary structure of Kir6.1 is not involved in the genetic pathogenesis of essential hypertension in Chinese Han hypertensive patients and has no effect on the BP response to iptakalim treatment.

Immunological features in patients with pneumonitis due to influenza A H1N1 infection

BACKGROUND

Pneumonitis induced by pandemic influenza A H1N1 has a potential to cause respiratory failure, which is a risk factor for death. The underlying immunopathological mechanisms, however, have not yet been fully elucidated.

PATIENTS AND METHODS

We investigated changes in plasma cytokines, T cell subsets, and C-reactive protein (CRP) in 16 hospitalized patients with pneumonia caused by 2009 H1N1 influenza infection. The patients were classified into a severe disease group and a mild disease group according to PaO2.

RESULTS

Cytokine profiles showed no changes in interferon gamma (IFN-gamma), interleukin 6 (IL-6), IL-8, or transforming necrosis factor alpha (TNF-alpha) levels throughout the observation period. Transforming growth factor beta (TGF-beta1) was overproduced in the severe group but not in the mild group. Accordingly, we also found some signs of pulmonary fibrosis during the recovery period. Elevated CRP levels and lymphopenia were common in both the severe and the mild group. After treatment, there was a significant elevation in lymphocytes in both groups, but a significant decrease in CRP in the mild group. Lymphocyte counts and CRP levels rapidly recovered to normal levels in all survivors posttreatment; otherwise it seemed to be related to poor prognosis.

CONCLUSIONS

Serial measurements of cytokines showed that only TGF-beta1 was overproduced, possibly in relation to the early use of corticosteroids, which may have downregulated immune responses to H1N1 infection. Pretreatment TGF-beta1 plasma concentrations and absolute lymphocyte counts were independent predictors of severity. However, the role of elevated TGF-beta1 in H1N1 infection-associated pulmonary fibrosis requires further investigation.

Increased levels of soluble vascular endothelial cadherin are associated with poor outcome in severe sepsis

Endothelial cells are thought to play a key role in sepsis pathogenesis: vascular endothelial damage occurs in severe sepsis and multiple organ dysfunction. Soluble vascular endothelial cadherin (VE-cadherin) levels were investigated in a prospective study involving 28 consecutive critically ill patients with or without severe sepsis who were admitted to surgical intensive care; 13 healthy age-matched volunteers were included as controls. Soluble VE-cadherin levels increased significantly in patients with severe sepsis compared with ill patients without severe sepsis and healthy controls. There was a significant linear correlation between soluble VE-cadherin levels and illness severity scores. Soluble VE-cadherin levels were significantly higher in patients who died compared with survivors. In vitro cell culture showed that serum from patients with severe sepsis greatly decreased VE-cadherin staining at intercellular junctions and total VE-cadherin expression in human umbilical cord vein endothelial cells. These findings suggest that endothelial cells play an important role in the poor outcome of patients with severe sepsis.

Multimodality imaging of hypoxia in preclinical settings

Hypoxia has long been recognized to influence solid tumor response to therapy. Increasingly, hypoxia has also been implicated in tumor aggressiveness, including growth, development and metastatic potential. Thus, there is a fundamental, as well as a clinical interest, in assessing in situ tumor hypoxia. This review will examine diverse approaches focusing on the preclinical setting, particularly, in rodents. The strategies are inevitably a compromise in terms of sensitivity, precision, temporal and spatial resolution, as well as cost, feasibility, ease and robustness of implementation. We will review capabilities of multiple modalities and examine what makes them particularly suitable for investigating specific aspects of tumor pathophysiology. Current approaches range from nuclear imaging to magnetic resonance and optical, with varying degrees of invasiveness and ability to examine spatial heterogeneity, as well as dynamic response to interventions. Ideally, measurements would be non-invasive, exploiting endogenous reporters to reveal quantitatively local oxygen tension dynamics. A primary focus of this review is magnetic resonance imaging (MRI) based techniques, such as ¹⁹F MRI oximetry, which reveals not only hypoxia in vivo, but more significantly, spatial distribution of pO₂ quantitatively, with a precision relevant to radiobiology. It should be noted that preclinical methods may have very different criteria for acceptance, as compared with potential investigations for prognostic radiology or predictive biomarkers suitable for use in patients.

Tumor necrosis factor alpha increases epithelial barrier permeability by disrupting tight junctions in Caco-2 cells

The objectives of this study were to determine the effect of tumor necrosis factor alpha (TNF-alpha) on intestinal epithelial cell permeability and the expression of tight junction proteins. Caco-2 cells were plated onto Transwell microporous filters and treated with TNF-alpha (10 or 100 ng/mL) for 0, 4, 8, 16, or 24 h. The transepithelial electrical resistance and the mucosal-to-serosal flux rates of the established paracellular marker Lucifer yellow were measured in filter-grown monolayers of Caco-2 intestinal cells. The localization and expression of the tight junction protein occludin were detected by immunofluorescence and Western blot analysis, respectively. SYBR-Green-based real-time PCR was used to measure the expression of occludin mRNA. TNF-alpha treatment produced concentration- and time-dependent decreases in Caco-2 transepithelial resistance and increases in transepithelial permeability to the paracellular marker Lucifer yellow. Western blot results indicated that TNF-alpha decreased the expression of phosphorylated occludin in detergent-insoluble fractions but did not affect the expression of non-phosphorylated occludin protein. Real-time RT-PCR data showed that TNF-alpha did not affect the expression of occludin mRNA. Taken together, our data demonstrate that TNF-alpha increases Caco-2 monolayer permeability, decreases occludin protein expression and disturbs intercellular junctions.

Mechanism of the transforming growth factor-beta induction of fibronectin expression in hepatic stem-like cells

Transforming growth factor-beta1 (TGF-beta1) plays an important role in the fibrogenic process in the liver. The aim of the present study was to explore the action of TGF-beta1 on fibronectin expression in rat hepatic stem-like cells and the underlying mechanisms. The level of fibronectin expression was determined in hepatic stem-like cells (WB cells) before and after TGF-beta1 stimulation by RT-PCR and Western blot methods. Using immunogold transmission electron microscopy and the Western blot method, we observed the result of the expression and the distribution of cAMP, phosphorylated Smad3 and Smad7 before and after TGF-beta1 treatment. The levels of fibronectin expression in both mRNA and protein increased 4- to 5-fold after TGF-beta1 stimulation, reaching an optimum level after 8 h and then gradually falling back. Similarly, TGF-beta1 stimulation resulted in an increase of cAMP in WB cells, peaking at 8 h. After treatment with TGF-beta1 for 24 h, the expression of cAMP gradually decreased. In addition, we found that TGF-beta1 treatment also contributed to the increased expression and to changes in cellular distribution of phosphorylated Smad3 (translocation from the cytoplasm to the nucleus) and Smad7 (translocation from the nucleus to the cytoplasm) in WB cells. The present study demonstrates that TGF-beta is involved in the fibrogenic process in hepatic stem cells through up-regulation of fibronectin expression, and the mechanisms underlying this process may be associated with the activation of cAMP and Smad pathways.