Chemometric Models for Quantification of Carbamazepine Anhydrous and Dihydrate Forms in the Formulation

Carbamazepine (CBZ) exists in anhydrous and dihydrate forms. These forms differ in their solubility, dissolution rate, and subsequently in their oral bioavailability. The objective of this study is to develop multivariate chemometric models for estimation of the low level of carbamazepine dihydrate (CBZ-DH) in the CBZ formulations containing excipients of the commercial formulation. The selected excipients were mixed in proportions to make sample matrices ranging from 0% to 50% CBZ-DH. Fourier transform infrared (FTIR), near infrared (NIR), and hyperspectral imaging data were mathematically pretreated before the development of partial least square and principal component analysis regression models. The developed partial least squares regression and principal component analysis models demonstrated predictability of CBZ and CBZ-DH by multiple scattering correction and standard normal variate processing methods. Among the spectroscopic techniques used the model performance parameters such as root-mean-square error, standard error, and bias were found to be low for NIR compared to FTIR. The treated data have shown better model fitting than without treatment, which was demonstrated by correlation coefficient of 0.9778, 0.9824, and 0.9852 for FTIR, NIR, and hyperspectral imaging, respectively. Furthermore, the predicted values were found to be very close to the selected low level of independent samples having 5% CBZ-DH in tablet formulation.     

Crystallization of Cyclophosphamide Monohydrate During Lyophilization

The purpose of this study was to investigate the phase behavior of cyclophosphamide (CPA) during various stages of lyophilization, with special emphasis on obtaining crystalline CPA monohydrate (CPA-MH) in the lyophilized product. Subambient differential scanning calorimetry and low-temperature X-ray diffractometry (LTXRD) were used to study the phase behavior of CPA solution (3.7% w/v). In situ lyophilization in LTXRD chamber was used to monitor the phase transitions occurring during the drying stages. Finally, the implications of these findings were confirmed by freeze-drying the aqueous solution in a laboratory-scale freeze-dryer. The results suggested that CPA remains amorphous during freeze concentration, with a T_g' of ?50°C. However, its crystallization as CPA-MH can be induced by annealing the frozen solution between ?5°C and ?10°C. In situ lyophilization in LTXRD showed that the CPA-MH crystallized during annealing, rapidly dehydrated during primary drying, thereby causing structural collapse. The dehydration of CPA-MH can be prevented by lowering the escaping tendency of water molecules from the crystal lattice of CPA-MH by maintaining the chamber pressure to 300, 400, or 500 mTorr. This study highlights the relationship of process parameters used during lyophilization with the solid form of lyophilized CPA.     

利用环介导等温扩增技术检测新型隐球菌

目的：建立一种快速检测新型隐球菌的方法。方法根据新型隐球菌的18 S rRNA基因序列设计内外引物各一对,在不同温度下对新型隐球菌进行环介导等温扩增,以探明环介导等温扩增法检测新型隐球菌最适宜的温度。对新型隐球菌、其他几种常见引起脑膜炎的病原菌以及部分种类的念珠菌进行扩增,以研究环介导等温扩增技术检测隐球菌的特异性。将新鲜培养的新型隐球菌稀释后加入非隐球菌感染患者的脑脊液中,模拟脑膜炎感染后的脑脊液环境,以研究环介导等温扩增技术检测新型隐球菌的敏感性。结果环介导等温扩增法检测新型隐球菌在60℃～65℃条件下均能实现良好扩增。环介导等温扩增法对其他病原菌的检测结果均为阴性,仅新型隐球菌的检测结果为阳性,特异性达到100%。用环介导等温扩增法从脑脊液中检测新型隐球菌的最低检出限为102 CFU/ml。用环介导等温扩增技术检测新型隐球菌性脑膜炎,能节省培养及传统鉴定的时间,从DNA的提取至反应结束在2～3h内即可完成,大大减少了诊断所需时间。结论环介导等温扩增是一种灵敏度高,特异性强,耗时短,且操作简便的检测新型隐球菌感染的方法。     

Increased Salt Intake Decreases Diet-Induced Thermogenesis in Healthy Volunteers: A Randomized Placebo-Controlled Study

High salt intake ranks among the most important risk factors for noncommunicable diseases. Western diets, which are typically high in salt, are associated with a high prevalence of obesity. High salt is thought to be a potential risk factor for obesity independent of energy intake, although the underlying mechanisms are insufficiently understood. A high salt diet could influence energy expenditure (EE), specifically diet-induced thermogenesis (DIT), which accounts for about 10% of total EE. We aimed to investigate the influence of high salt on DIT. In a randomized, double-blind, placebo-controlled, parallel-group study, 40 healthy subjects received either 6 g/d salt (NaCl) or placebo in capsules over 2 weeks. Before and after the intervention, resting EE, DIT, body composition, food intake, 24 h urine analysis, and blood pressure were obtained. EE was measured by indirect calorimetry after a 12 h overnight fast and a standardized 440 kcal meal. Thirty-eight subjects completed the study. Salt intake from foods was 6 g/d in both groups, resulting in a total salt intake of 12 g/d in the salt group and 6 g/d in the placebo group. Urine sodium increased by 2.29 g/d (p < 0.0001) in the salt group, indicating overall compliance. The change in DIT differed significantly between groups (placebo vs. salt, p = 0.023). DIT decreased by 1.3% in the salt group (p = 0.048), but increased by 0.6% in the placebo group (NS). Substrate oxidation indicated by respiratory exchange ratio, body composition, resting blood pressure, fluid intake, hydration, and urine volume did not change significantly in either group. A moderate short-term increase in salt intake decreased DIT after a standardized meal. This effect could at least partially contribute to the observed weight gain in populations consuming a Western diet high in salt.     

Comparison of high-dose and low-dose corticosteroid therapy for refractory Mycoplasma pneumoniae pneumonia in children

Background

Mycoplasma pneumoniae pneumonia (MPP) is generally a self-limiting disease, but it may become refractory. It is thought that refractory MPP is linked to the excessive immunologic responses of the host. Consequently, the use of adjunctive systemic corticosteroids may have beneficial effects. In this study, we compared the effects of high- and low-dose corticosteroid therapy in a pediatric population with refractory MPP.