[Comparative study on Sichuan yak pericardium and Australian cattle pericardium].

Currently, as the key raw material of artificial biological heart valve, bovine pericardium is mainly depend on import and has become a "bottleneck" challenge, greatly limiting the development of domestic biological heart valve. Therefore, the localization of bovine pericardium is extremely urgent. In this study, the pericardium of Sichuan yak was compared with that of Australian cattle in terms of fundamental properties and anti-calcification performance. The results demonstrated that the appearance and thickness of yak pericardium were more advantageous than the Australian one. Sichuan yak pericardium and Australian cattle pericardium had comparable performance in shrinkage temperature, mechanical test and anti-calcification test. This study preliminarily verifies the feasibility of substitution of Australian cattle pericardium by Sichuan yak pericardium and promotes the progression of bovine pericardium localization with data support.

Disruption of regional homogeneity in the brains of chronic methamphetamine users.

Previous studies have reported evidence supporting structural and functional alterations in the brains of methamphetamine (MA) users. The aim of the present study was to extend current knowledge regarding brain function(s) in MA users by examining regional homogeneity (ReHo). Chronic MA users (51 male, 46 female), who were undergoing supervised abstinence for 12 to 621 days, and 79 healthy controls (43 male, 36 female) underwent resting-state functional brain magnetic resonance imaging. Voxel-wise whole-brain scale group differences in ReHo were examined. The mean ReHo values of significant clusters were extracted, and linear regression was used to identify factors that contributed to these mean ReHo values. MA users exhibited lower ReHo values in the left orbital part of the inferior frontal gyrus extending to the left insula and left temporal pole, left amygdala, and left fusiform gyrus. MA users also exhibited greater ReHo values in the bilateral pre- and postcentral gyri and right cerebellum. Characteristics of MA use, including duration, duration of abstinence from MA, and age at onset of MA use, demonstrated no reliable contribution to ReHo of the significant clusters. Findings of the present study demonstrated that chronic MA use was associated with regional specific disruption of ReHo, which is relatively independent of structural and functional alterations and, apparently, does not recover after relatively long-term abstinence. This disruption may underlie overall neurocognitive deficits in MA users, which is difficult to recover.

[Study of No Observed Adverse Effect Level of Nickel and Its Preliminary Evaluation Biocompatibility].

The purpose of this study was to investigate the NOAEL of the nickel ion and provide with basic data for the biological evaluation of those medical devices containing nickel. Five groups SD rats were repeatedly exposed during 14 d respectively to nickel at first stage doses of 4.9, 3.7, 2.5 mg/(kg.d), and the second stage doses of 1.2, 0.25 mg/(kg.d) by the intravenous route. The results showed that the NOAEL of nickel ion is 0.25 mg/(kg.d) for SD rats, and the result was verified by subchronic systemic toxicity test of nickel alloy. The threshold of toxicological concern (TTC) of nickel is 150 µg/d (based on application of 100-fold uncertainty factor and a body weight of 60 kg)deduced by these data.

Gray-matter structure in long-term abstinent methamphetamine users.

BACKGROUND: Previous studies of brain structure in methamphetamine users have yielded inconsistent findings, possibly reflecting small sample size and inconsistencies in duration of methamphetamine abstinence as well as sampling and analyses methods. Here we report on a relatively large sample of abstinent methamphetamine users at various stages of long-term abstinence. METHODS: Chronic methamphetamine users (n = 99), abstinent from the drug ranging from 12 to 621 days, and healthy controls (n = 86) received T1-weighted structural magnetic resonance imaging brain scans. Subcortical and cortical gray-matter volumes and cortical thickness were measured and the effects of group, duration of abstinence, duration of methamphetamine use and onset age of methamphetamine use were investigated using the Freesurfer software package. RESULTS: Methamphetamine users did not differ from controls in gray-matter volumes, except for a cluster in the right lateral occipital cortex where gray-matter volume was smaller, and for regions mainly in the bilateral superior frontal gyrui where thickness was greater. Duration of abstinence correlated positively with gray-matter volumes in whole brain, bilateral accumbens nuclei and insulae clusters, and right hippocampus; and with thickness in a right insula cluster. Duration of methamphetamine use correlated negatively with gray-matter volume and cortical thickness of a cluster in the right lingual and pericalcarine cortex. CONCLUSIONS: Chronic methamphetamine use induces hard-to-recover cortical thickening in bilateral superior frontal gyri and recoverable volumetric reduction in right hippocampus, bilateral accumbens nuclei and bilateral cortical regions around insulae. These alternations might contribute to methamphetamine-induced neurocognitive disfunctions and reflect a regional specific response of the brain to methamphetamine.

Factors affecting the occurrence of psychotic symptoms in chronic methamphetamine users.

Studies of risk for psychotic symptoms in methamphetamine users have focused primarily on drug use immediately before symptoms had appeared. Here we assessed factors reflecting characteristics of lifetime methamphetamine use before the appearance of psychotic symptoms. Four hundred ninety-five methamphetamine users (322 men, 173 women) were studied with consideration of the following features of methamphetamine use: age of initiation, maximum single dose, number of uses at or near the maximum dose, longest period of daily use, average dosage during that period, number of heavy use periods, and number of sustained abstinence periods (>1 month). Use of drugs other than methamphetamine and family history of schizophrenia were also considered. Retrospective self-reports of psychotic symptoms were obtained on the Brief Psychiatric Rating Scale. Factors associated with the occurrence of initial psychotic symptom(s) were identified using logistic regression. Later age of initiation, more uses at maximal or near maximal dosage, and more periods of prolonged abstinence were identified as protective factors. We conclude that early methamphetamine use can promote psychotic symptoms, possibly by altering neurodevelopment, whereas long abstinence periods may protect by allowing recovery. Negative associations of the appearance of psychotic symptom(s) with frequent high-dose administration suggest protection through tolerance.

[Research on Endothelial Cytocompatibility of Magnesium Alloy].

In-stent restenosis is a main problem in the application of stents. It has been proved that rapid endothelialization of stents after implantation is the key point for solving the problem of restenosis. Recent years researchers focus on developing biodegradable magnesium alloy stents. The cytocompatibility is essential for the design of magnesium alloy stents. In this article, recent research about the endothelial cytocompatibility of magnesium alloy was reviewed, including methods, results, shortcomings and advice.

[In Vitro Cytotoxicity Study of Nickel Ion].

The purpose of this study was to investigate the cytotoxicity of the nickel ion and provide with basic data for the biological evaluation of those medical devices containing nickel. Seven cell lines were chosen. They were L929, h9c2(2-1), 293[HEK-293], hFOB1.19, THLE-3, H9 and IM-9 respectively. According to the principle of biological evaluation of medical devices, MTT method was chosen to test the cytotoxicity in different concentrations of nickel ion. For each cell line, the relative growth rate (RGR) was obtained and the cytotoxic grade was classified. Besides, IC50 values were calculated. As a result, it was found that the sensitivity was different among all cell lines. H9 was the most sensitive one, while the L929 was the most tolerant one. The concentration which is not above 1.25 mg/L was safe for all seven cell lines, because the cytotoxicity for all cells exposed in this concentration were not higher than grade 1. According to the criteria for medical devices, the concentrations not above 5 mg/L were safe for L929 cells. This result helps us to roughly assess the cytotoxicity and systematic toxicity caused by nickel contained in medical devices.

[The investigation of nickel dissolution from nitinol under different extraction conditions in biological tests].

The dissolution of nickel from nitinol alloy under different extraction conditions was investigated when biological tests of nitinol medical devices were carried out. It discussed the equivalence of these extraction conditions and found the best extraction conditions. In the experiment, two brands of nitinol were chosen and extracted under different extraction conditions according to GB/T 16886-12. Plasma emission spectrometer was used to analyse the concentration of nickel in extract liquid. The results show that there is no equivalence among these extraction conditions for nitinol materials. And it is suggested that (37 +/- 1) degree C, (72 +/- 2) h could be used as normal extraction condition and (70 +/- 2) degrees C, (24 +/- 2) h as accelerated extraction condition.

A novel calcium phosphate ceramic-magnetic nanoparticle composite as a potential bone substitute.

A magnetic field has been applied to accelerate bone healing for a long time. In this study, in order to combine the bone repair capability of calcium phosphate (CaP) ceramics with the magnetic field, a novel CaP ceramic-magnetic nanoparticle (CaP-MNP) composite was fabricated through integrating the superparamagnetic nanoparticles into the CaP ceramics. Two kinds of CaP ceramics were chosen: hydroxyapatite (HA) and HA/tricalcium phosphate (65/35, HT). The samples were cultured with Ros17/2.8 and MG63 cells respectively in vitro to evaluate the cell proliferation and differentiation via MTT and alkaline phosphatase activity tests. In order to find the influence of the magnetic materials on the expression of the bone morphological protein (BMP), the samples composited with BMP-2 were implanted subcutaneously in the fasciae of rat back muscles for 30 days. Compared with ordinary CaP ceramics, the results indicated that the CaP-MNP composite had good biocompatibility and was able to promote cell proliferation and differentiation significantly. The in vivo test showed that the expression of BMP-2 would be accelerated by HT composited with MNPs, and new bone-like tissue formation could be observed. Accordingly, it might be expected that this CaP-MNP composite could become a potential bone substitute or bone tissue engineering scaffold.

A pH-sensitive nano drug delivery system derived from pullulan/doxorubicin conjugate.

A novel pH-sensitive nanoparticle drug delivery system for doxorubicin (DOX) is prepared. Pullulan, a natural biocompatible polysaccharide, was partly carboxymethylized; hydrazine hydrate was condensed with the carboxyl groups forming hydrazide. The hydrazide was coupled with DOX through the formation of hydrazone bond. The chemical structure of the conjugate was determined by FTIR and (1)H NMR. The pullulan/DOX conjugate nanoparticles were formed through the aggregation of hydrophobic DOX. The size and morphology of prepared nanoparticles were characterized using dynamic light scattering and transmission electron microscope. The results showed that the nanoparticles were spherical and their size was less than 100 nm. The content of DOX in conjugate was 3.18 wt %. The investigation of the release behavior in vitro indicated that the DOX was released from nanoparticles faster at pH 5.0 (62% DOX released within 24 h) than at pH 7.4 (29% DOX released within 24 h). The in vitro cytotoxicity of pullulan/DOX conjugate nanoparticles was tested by the MTT assay.