Preparation and characterization of co-processed starch/MCC/chitin hydrophilic polymers onto magnesium silicate

It was aimed to investigate the compressibility, compactibility, powder flow and tablet disintegration of a new excipient comprising magnesium (Mg) silicate co-processed (5%–85% w/w) onto chitin, microcrystalline cellulose (MCC) and starch as the hydrophilic polymers of interest. Initially, the mechanism of tablet disintegration was studied by measuring water infiltration rate, moisture sorption, swelling capacity and hydration ability. Moreover, the powders compression behavior was carried out by applying Kawakita model of compression analysis in addition to porosity and radial tensile strength measurements. In vitro drug release of compacts made of 400?mg ibuprofen and 300?mg of the hydrophilic polymers containing 30% w/w Mg silicate co-precipitate was investigated in phosphate buffer (pH 7.8). This work demonstrated that the incorporation of Mg silicate to the hydrophilic polymers lead to the improvement of powder flowability, compactibility, stability (with regard to storage conditions), compacts crushing strength, and disintegration time in addition to faster drug release. The overall findings are practically advantageous in the context of finding a low cost and multifunctional co-processed excipient of natural origins.     

Mechanical and Biological Properties of a Biodegradable Mg‐Zn‐Ca Porous Alloy

Objectives

As promising alternative to current metallic biomaterials, the porous Mg scaffold with a 3‐D open‐pore framework has drawn much attention in recent years due to its suitable biodegradation, biocompatibility, and mechanical properties for human bones. This experiment's aim is to study the mechanical properties, biosafety, and osteogenesis of porous Mg‐Zn alloy.

Methods

A porous Mg‐2Zn‐0.3Ca (wt%) alloy was successfully prepared by infiltration casting, and the size of NaCl particles was detected by a laser particle size analyzer. The microstructure of the Mg‐2Zn‐0.3Ca alloy was characterized by the stereoscopic microscope and Sirion Field emission scanning electron microscope. X‐ray computerized tomography scanning (x‐CT) was used to create the 3‐D image. The degradation rate was measured using the mass loss method and the pH values were determined together. The engineering stress–strain curve, compressive modulus, and yield strength were tested next. The bone marrow stromal cells (BMSC) were cultured in vitro. The CCK‐8 method was used to detect the proliferation of the BMSC. Alkaline phosphatase (ALP) and alizarin red staining were used to reflect the differentiation effects. After co‐culturing, cell growth on the material's surface was observed by scanning electron microscope (SEM). The cell adhesion was tested by confocal microscopy.

Results

The obtained results showed that by using near‐spherical NaCl filling particles, the porous Mg alloy formed complete open‐cell foam with a very uniform size of pores in the range of 500–600 μm. Benefitting from the small size and uniform distribution of pores, the present porous alloy exhibited a very high porosity, up to 80%, and compressive yield strength up to 6.5 MPa. The degradation test showed that both the pH and the mass loss rate had similar change tendency, with a rapid rise in the early stage for 1–2 day's immersion and subsequently remaining smooth after 3 days. In vitro cytocompatibility trials demonstrated that in comparison with Ti, the porous alloy accelerated proliferation in 1, 3, 5, and 7 days (P < 0.001), and the osteogenic differentiation test showed that the ALP activity in the experimental group was significantly higher (P = 0.017) and has more osteogenesis nodules. Cell adhesion testing showed good osteoconductivity by more BMSC adhesion around the holes. The confocal microscopy results showed that cells in porous Mg‐based alloy had better cytoskeletal morphology and were larger in number than in titanium.

Conclusions

These results indicated that this porous Mg‐based alloy fabricated by infiltration casting shows great mechanical properties and biocompatibilities, and it has potential as an ideal bone tissue engineering scaffold material for bone regeneration.

     

帕金森大鼠黑质外液和红细胞内Mg2+含量的变化

目的:观察帕金森病(PD)大鼠中脑黑质外液及红细胞内Mg~(2+)浓度的改变。方法:采用6-羟基多巴(6-OHDA)损毁制备偏侧PD大鼠模型24只,分4组各6只,分别于造模后第7、14、21、28天采集大鼠动脉血中的红细胞,采用微透析技术收集中脑黑质细胞外液,火焰原子吸收光谱法测定红细胞内和黑质细胞外液Mg~(2+)含量。选5只健康大鼠作为对照组,进行相同测定。结果:各时点PD组红细胞内Mg~(2+)含量均显著低于对照组(P<0.05),且随病程延长而逐渐下降(P<0.05);但PD组中脑黑质细胞外液Mg~(2+)含量仅在第21、28天明显低于对照组(P<0.05)。结论:Mg~(2+)缺乏与PD的发生及病程进展有一定关联。     

Protective effects of a magnesium magnetic isotope (Mg25)‐exchanging nanoparticle (25MgPMC16) on mitochondrial functional disorders in esmolol‐induced cardiac arrest in rats

1 In cardiac surgery, agents are needed to produce temporary cardiac arrest (cardioplegia). One of these agents is esmolol (ESM) which is a short‐acting selective beta‐1 adrenergic receptor antagonist and its overdose causes diastolic ventricular arrest. 2 The ²⁵MgPMC₁₆ (porphyrin adducts of cyclohexil fullerene‐C60) is known as a nanoparticle which has a cardioprotective effect when the heart is subjected to stressful conditions. 3 In this study, we aimed to confirm the deleterious effects of ESM overdose on cardiac mitochondria and identify any protective effects of ²⁵MgPMC₁₆ in male Wistar rats. Esmolol 100 mg kg^?1 (LD50 = 71 mg kg^?1) was injected intravenously (i.v.) into tail vein to induce cardiac arrest. This dose was obtained from an ESM dose–response curve which induces at least 80% arrest in rats. 4 ²⁵MgPMC₁₆ at three different doses (45, 90 and 224 mg kg^?1) was injected i.v. as pretreatment, eight hours before ESM injection. ²⁵MgCl₂ or ²⁴MgPMC₁₆ were used as controls. Following cardiac arrest, the heart was removed and the mitochondria extracted. Mitochondrial viability and the adenosine 5′‐diphosphate sodium salt hydrate/Adenosine 5′‐triphosphate disodium salt hydrate (ADP/ATP) ratio were measured as biomarkers of mitochondrial function. 5 Results indicate that ²⁵MgPMC₁₆ caused a significant increase in mitochondrial viability and decrease in ADP/ATP ratio. No significant changes were seen with ²⁴MgPMC₁₆ or ²⁵MgCl₂. It is concluded that cardiac arrest induced by ESM overdose leads to a significant decrease in mitochondrial viability and their ATP levels, whereas pretreatment by ²⁵MgPMC₁₆ can protect mitochondria by increasing ATP level through liberation of Mg into cells and the improvement of hypoxia.     

Biomarker for early renal microvascular and diabetic kidney diseases

Recognition of early stage of diabetic kidney disease, under common practice using biomarkers, namely microalbuminuria, serum creatinine level above 1?mg/dL and accepted definition of diabetic kidney disease associated with creatinine clearance value below 60?mL/min/1.73?m², is unlikely. This would lead to delay treatment associated with therapeutic resistance to vasodilator due to a defective vascular homoeostasis. Other alternative biomarkers related to the state of microalbuminuria is not sensitive to screen for early diabetic kidney disease (stages I, II). In this regard, a better diagnostic markers to serve for this purpose are creatinine clearance, fractional excretion of magnesium (FE Mg), cystatin C. Recently, renal microvascular disease and renal ischemia have been demonstrated to correlate indirectly with the development of diabetic kidney disease and its function. Among these are angiogenic and anti-angiogenic factors, namely VEGF, VEGF receptors, angiopoietins and endostatin. With respect to therapeutic prevention, implementation of treatment at early stage of diabetic and nondiabetic kidney disease is able to restore renal perfusion and function.     

Microstructure,mechanical and corrosion properties of Mg–Dy–Gd–Zr alloys for medical applications

In previous investigations, a Mg–10Dy (wt.%) alloy with a good combination of corrosion resistance and cytocompatibility showed great potential for use as a biodegradable implant material. However, the mechanical properties of Mg–10Dy alloy are not satisfactory. In order to allow the tailoring of mechanical properties required for various medical applications, four Mg–10(Dy + Gd)–0.2Zr (wt.%) alloys were investigated with respect to microstructure, mechanical and corrosion properties. With the increase in Gd content, the number of second-phase particles increased in the as-cast alloys, and the age-hardening response increased at 200 °C. The yield strength increased, while the ductility reduced, especially for peak-aged alloys with the addition of Gd. Additionally, with increasing Gd content, the corrosion rate increased in the as-cast condition owing to the galvanic effect, but all the alloys had a similar corrosion rate (～0.5 mm year^?1) in solution-treated and aged condition.     

Improvement of Renal Function in Type 2 Diabetic Nephropathy

Background. Therapeutic failure in preventing renal disease progression in type 2 diabetic nephropathy (DN) is due to a failure in the early detection of DN by microalbuminuria and the inappropriate correction of renal hemodynamic maladjustment secondary to glomerular endothelial dysfunction. Methods. Thirty patients associated with normoalbuminuric type 2 DN were subject to the following studies: tubular function by means of fractional excretion of magnesium (FE Mg), vascular function by means of determining the circulating endothelial cell, VEGF, VEGF/TGF B ratio, and intrarenal hemodynamic studies. Results. FE Mg, circulating endothelial cells, and TGF B were abnormally elevated, and VEGF/TGF B ratio was decreased in these normoalbuminuric patients. The intrarenal hemodynamic study revealed a hemodynamic maladjustment characterized by a preferential constriction at the efferent arteriole and a reduction in peritubular capillary flow. Following treatment with vasodilators, a decrease in efferent arteriolar resistance and increase in peritubular capillary flow as well as glomerular clearance were observed. Conclusion. FE Mg appears to be a more sensitive marker than microalbuminuria for the early detection of DN. Increased endothelial cell injury is reflected by enhanced circulating endothelial cell loss in conjunction with the increased TGF B and the decreased ratio between VEGF and TGF B. This is further supported by the dysfunctioning glomerular endothelium, which is characterized by hemodynamic maladjustment and a reduction in the peritubular capillary flow. A correction of such hemodynamic maladjustment by multidrug vasodilators effectively improves renal perfusion and restores renal function in type 2 DN.     

Serum levels of polyunsaturated fatty acids are low in Chinese men with metabolic syndrome,whereas serum levels of saturated fatty acids,zinc, and magnesium are high

The purpose of this study was to examine the hypothesis that serum levels of phospholipid (PL) fatty acids (FA) and minerals are associated with the components of metabolic syndrome (MetS) in the Chinese population and the profiles of changes may differ from patients with MetS from Western countries. The levels of serum PL, FA, and minerals were examined in 201 subjects (52 with MetS and 149 healthy controls without any MetS components) in China. The saturated FA proportion in serum was significantly higher, whereas the proportion of total polyunsaturated FA (PUFA), n-3 and n-6 PUFA (22:6n-3: −16%, P = .006; 20:4n-6: −36%, P < .001), and estimated δ-5 desaturase were significantly lower in the MetS group compared with those that are not MetS. Subjects with MetS had higher levels of serum Zn (P = .037) and Mg (P < .001) than subjects without MetS. The proportion of n-3 PUFA was significantly negatively correlated with body mass index and waist circumference. In conclusion, serum PL FA composition and serum minerals in Chinese men with MetS differed significantly from that of healthy individuals, reflecting a decrease in n-3 and n-6 PUFA, especially 22:6n-3 and 20:4n-6, and an increase in saturated FA, magnesium, and zinc. These changes may reflect improper dietary intake in subjects with MetS, and dietary modification could be useful to prevent MetS and as an adjunctive therapy.     

亚低温对大鼠急性脑梗死后脑组织内Ca2+、Mg2+、EAA及血浆ET变化的影响

目的　探讨亚低温对大鼠急性脑梗死后脑组织内Ca2 + 、Mg2 + 、兴奋性氨基酸 (EAA)及血浆内皮素 (ET)变化的影响及意义。方法　将 48只SD大鼠随机分为亚低温组及对照组 ,各组再分为 4个亚组 ,每亚组 6只 ,应用改良线拴法制备大鼠大脑中动脉梗死模型 ;亚低温组大鼠给予亚低温治疗 ,而对照组不作亚低温处理。分别于缺血后 1h、2h、4h、8h处死 1亚组 ,检测缺血区脑组织内Ca2 + 、Mg2 + 、EAA及血浆ET含量。结果　亚低温组大鼠缺血区脑组织内Ca2 + 、Mg2 + 、EAA及血浆ET含量随着缺血时间的延长仅轻度升高 ,Mg2 + 含量的下降也不明显 ,与对照组同时段比较差异有显著性 (P <0 .0 1)。结论　亚低温能明显阻止实验大鼠脑缺血后缺血区脑组织内损伤性因子Ca2 + 、EAA和ET含量的增高及保护性因子Mg2 + 的下降 ,具有脑保护作用