Improving temperature characteristics of GaN-based ultraviolet laser diodes by using InGaN/AlGaN quantum wells.

Temperature characteristics of GaN-based laser diodes are investigated. It is noted that the characteristic temperature of the threshold current (T0) decreases with decreasing lasing wavelength for GaN-based LDs. The performance deteriorates seriously for UV LDs at high temperature. It is ascribed to the increase of carriers escaping from quantum wells due to the lower potential barrier height. In this Letter, AlGaN is used as the barrier layer in UV LDs instead of GaN to improve the temperature characteristic of the threshold current and slope efficiency by increasing the potential barrier height of quantum wells. Based on this structure, a high output power of 4.6 W is obtained at the injection current of 3.8 A; its lasing wavelength is 386.8 nm.

Mesoporous silica nanoparticles with chiral pattern topological structure function as "antiskid tires" on the intestinal mucosa to facilitate oral drugs delivery.

The weak adhesion between nanocarriers and the intestinal mucosa was one of the main reasons caused the failure in oral delivery. Inspired by the "antiskid tires" with complex chiral patterns, mesoporous silica nanoparticles AT-R@CMSN exhibiting geometrical chiral structure were designed to improve the surface/interface roughness in nanoscale, and employed as the hosting system for insoluble drugs nimesulide (NMS) and ibuprofen (IBU). Once performing the delivery tasks, AT-R@CMSN with rigid skeleton protected the loaded drug and reduced the irritation of drug on gastrointestinal tract (GIT), while their porous structure deprived drug crystal and improved drug release. More importantly, AT-R@CMSN functioned as "antiskid tire" to produce higher friction on intestinal mucosa and substantively influenced multiple biological processes, including "contact", "adhesion", "retention", "permeation" and "uptake", compared to the achiral S@MSN, thereby improving the oral adsorption effectiveness of such drug delivery systems. By engineering AT-R@CMSN to overcome the stability, solubility and permeability bottlenecks of drugs, orally administered NMS or IBU loaded AT-R@CMSN could achieve higher relative bioavailability (705.95% and 444.42%, respectively) and stronger anti-inflammation effect. In addition, AT-R@CMSN displayed favorable biocompatibility and biodegradability. Undoubtedly, the present finding helped to understand the oral adsorption process of nanocarriers, and provided novel insights into the rational design of nanocarriers.

Room temperature continuous-wave operated 2.0-W GaN-based ultraviolet laser diodes.

Temperature characteristics of near-UV laser diodes (LDs) with a lasing wavelength of 384 nm are investigated. The characteristic temperature of threshold current (T0) of the UV LDs is low. Thus, the performance of the UV LDs under continuous wave (CW) operation is not as good as under pulsed operation especially at a high injection current. In addition, it is found that self-heating is a key factor for CW characteristics of the UV LDs, where suppression of the self-heating by using thick waveguide layers can increase the critical current of thermal rollover of the UV LD's operation. A high CW output power of 2.0 W is achieved for an InGaN near-UV LD with the n-side down on a sub-mount, whose threshold current density is 1.27 kA/cm2 and the highest wall plug efficiency (WPE) is approximately 15.9% at an injection current of 1.2 A.

Comparative effect of ciprofloxacin and moxifloxacin on the modulation of bile acid profiles and gut microbiota in rats

Abstract Fluoroquinolones are an important class of antimicrobial agents to manage infectious diseases. However, knowledge about how host bile acids are modified by fluoroquinolones is limited. We investigated and compared the impact of fluoroquinolones on circulating bile acid profiles and gut microbiota from in vivo studies. We administered ciprofloxacin (100 mg/kg/day) or moxifloxacin (40 mg/kg/day) orally to male Wistar rats for seven days. Fifteen bile acids (BAs) from the serum and large intestine were quantified by HPLC-MS/MS. The diversity of gut microbiota after ciprofloxacin and moxifloxacin treatment was analyzed using high-throughput, next-generation sequencing technology. The two fluoroquinolone-treated groups had different BA profiles. Ciprofloxacin significantly reduced the hydrophobicity index of the BA pool, reduced secondary BAs, and increased taurine-conjugated primary BAs in both the serum and large intestine as compared with moxifloxacin. Besides, ciprofloxacin treatment altered intestinal microbiota with a remarkable increase in Firmicutes to Bacteroidetes ratio, while moxifloxacin exerted no effect. What we found suggests that different fluoroquinolones have a distinct effect on the host BAs metabolism and intestinal bacteria, and therefore provide guidance on the selection of fluoroquinolones to treat infectious diseases.

Mechanical intestinal obstruction due to isolated diffuse venous malformations in the gastrointestinal tract: A case report and review of literature.

BACKGROUND: Isolated gastrointestinal venous malformations (GIVMs) are extremely rare congenital developmental abnormalities of the venous vasculature. Because of their asymptomatic nature, the diagnosis is often quite challenging. However, as symptomatic GIVMs have nonspecific clinical manifestations, misdiagnosis is very common. Here, we report a case of isolated diffuse GIVMs inducing mechanical intestinal obstruction. A literature review was also conducted to summarize clinical features, diagnostic points, treatment selections and differential diagnosis in order that doctors may have a comprehensive understanding of this disease. CASE SUMMARY: A 50-year-old man presented with recurrent painless gastrointestinal bleeding for two months and failure to pass flatus and defecate with nausea and vomiting for ten days. Digital rectal examination found bright red blood and soft nodular masses 3 cm above the anal verge. Computed tomography showed that part of the descending colon and rectosigmoid colon was thickened with phleboliths in the intestinal wall. Colonoscopy exhibited bluish and reddish multinodular submucosal masses and flat submucosal serpentine vessels. Endoscopic ultrasonography showed anechoic cystic spaces within intestinal wall. The lesions were initially thought to be isolated VMs involving part of the descending colon and rectosigmoid colon. Laparoscopic subtotal proctocolectomy, pull-through transection and coloanal anastomosis and ileostomy were performed. Histopathology revealed intact mucosa and dilated, thin-walled blood vessels in the submucosa, muscularis, and serosa involving the entire colorectum. The patient recovered with complete symptomatic relief during the 52-mo follow-up period. CONCLUSION: The diagnosis of isolated GIVMs is challenging. The information presented here is significant for the diagnosis and management of symptoms.

The effect of food intake on the pk of rhein released from diacerein

Diacerein is a symptomatic slow-acting drug used for treating osteoarthritis. This drug is completely metabolized into the active metabolite rhein before reaching the systemic circulation. This study evaluated the effects of food on the pharmacokinetics of rhein released from diacerein in healthy Chinese subjects. This was a single-center, randomized, single-dose, open-label, two-period, cross-over study. Twenty-four healthy subjects were randomly selected to receive a single oral dose of 50 mg diacerein capsule in either fasted or fed state on two separate visits. Plasma samples were analyzed with LC-MS/MS. Pharmacokinetic parameters were calculated using WinNonlin software. In the fasted and fed states, the main pharmacokinetic parameters of diacerein capsule were as follows: Cmax were (4471 ± 936), (3225 ± 755) ng/mL, t1/2 were (4.22 ± 0.42), (4.19 ± 1.05) h, tmax were (2.61 ± 1.25), (3.81 ± 1.29) h, AUC0-24 h were (24223 ± 4895), (24316 ± 5856) h·ng/mL, and AUC0-∞ were (24743 ± 5046), (25170 ± 6415) h·ng/mL. The absorption rate of diacerein capsule was obviously delayed by food intake but the absorption degree remained unaffected.

Pharmacokinetics and safety of repirinast tablets in healthy Chinese subjects

ABSTRACT Repirinast is a new, synthetic, disodium cromoglycate-like antiallergic agent for oral administration in humans. This study evaluated the safety, tolerability and pharmacokinetics of repirinast tablets in healthy Chinese volunteers. This was a phase I, open-label, randomized, single- and multiple-dose study. Subjects were assigned to receive a single dose of repirinast tablet at either 150, 300, or 450 mg, or multiple doses of 150 mg twice daily for 5 days. Plasma samples were analyzed with LC-MS/MS. Pharmacokinetic parameters of active metabolite MY-1250 (deesterified repirinast) were calculated using non-compartmental analysis with WinNonlin software. Statistical analysis was performed using SPSS software. All adverse events (AEs) were mild and of limited duration. No serious adverse event (SAE), death or withdrawal from the study was observed. In the single-dose study, Cmax was reached at about 0.75 hour, and the mean t1/2 was approximately 16.21 hours. Area under curve (AUC) and Cmax increased with dose escalation, but dose proportionality was not observed over the range of 150 to 450 mg. In the multiple-dose study, the steady-state was reached within 3 days with no accumulation. Repirinast tablet was well tolerated in healthy Chinese subjects.

Expression of intestinal tight junction proteins in patients with non-alcoholic fatty liver disease.

BACKGROUND/AIMS: To investigate the expression of tight junction (TJ) proteins including Zonula occludens-1 (ZO-1), occludin and claudin-1 in intestinal epithelial cells in patients with non-alcoholic fatty liver disease (NAFLD) and study its potential association with the pathogenesis of NAFLD. METHODOLOGY: Twenty-eight NAFLD patients with elevated transaminase, 30 NAFLD patients with normal transaminase and 34 healthy volunteers were enrolled. Their biochemical characters were measured and the expression of ZO-1, occludin and claudin-1 proteins in intestinal epithelial cells was assessed by immunohistochemical analysis and its relationship with transaminase levels was also discussed. RESULTS: Significant differences were observed on the levels of BMI, TC, TG, FPG, ALT, and AST among the three groups. The levels in NAFLD patients with elevated transaminase were significantly higher than NAFLD patients with normal transaminase and the latter had higher levels than the volunteers. The expression of ZO-1 and occludin were significantly different among the three groups (chi2 = 14.210, p < 0.01; chi2 = 20.543, p < 0.01). The expression of ZO-1 and occludin decreased gradually from NAFLD with elevated transaminase to healthy volunteers (r = 0.386, p <0.01; r = 0.449, p < 0.01). In NAFLD patients, the levels of the expression of ZO-1 and occludin were negatively correlated with the transaminase level (r = -0.426, p < 0.01; r = -0.597, p < 0.01). The expression of claudin-1 was found among all the three groups but no statistical significance was observed among three groups (chi2 = 0.686, p = 0.953). CONCLUSIONS: The expression of TJ proteins in intestinal epithelial cells are closely related with the occurrence and development of NAFLD. The contribution of different TJ protein varies in maintaining barrier function.