偏侧咀嚼对大鼠咬肌PGE_2影响的研究

目的研究偏侧咀嚼对咬肌PGE2水平的影响。方法将48只SD大鼠,随机分为4个实验组和相应的对照组,每组各6只。实验组大鼠拔除左侧上下颌磨牙,并分别处死于拔牙后3天、2周、4周和12周。各组大鼠双侧咬肌PGE2含量采用放射免疫技术检测。结果 实验组拔牙侧和非拔牙侧咬肌PGE2含量与对照组对应侧比较有明显增加(P0.01),其中以4周组增高最明显。除3天组外,拔牙侧咬肌PGE2含量明显高于非拔牙侧(P0.01)。结论 PGE2参与咬肌损伤过程,且在偏侧咀嚼不同时间里,对双侧咬肌损伤程度不同。     

Eating habits in older people in Greece: The role of age, dental status and chewing difficulties

The aim of this study was to investigate the role of age-related parameters on the dietary preferences in a Greek community-dwelling sample. 130 participants aged between 18 and 92 years were interviewed and clinically examined. Data were collected on their socio-demographic characteristics, their dental status, the oral complaints, their chewing difficulties and the frequency of eating a variety of food types. The results revealed that increasing age was associated with increased frequency of consumption of fish, grains and vegetables. Impaired dental status and chewing difficulties did not affect the frequency of eating meat and other “difficult to chew” food, but it was related to more frequent consumption of softer food (chicken, fish, grains, and dairy products). The older Greeks did not exclude any food type from their diet, because of dental impairment. To overcome chewing problems they used various preparing methods to consume their favorite food. The dietary patterns of the older participants adhere to the traditional Mediterranean diet greater than those of the younger ones, revealing the various cultural and social parameters which influence food selection.     

Sham feed or sham? A meta-analysis of randomized clinical trials assessing the effect of gum chewing on gut function after elective colorectal surgery

Purpose  Enhanced recovery programs aim to expedite gut function after elective colorectal surgery. Early oral feeding simulates gut function but is not always feasible. Gum chewing, a form of sham feed, is an alternative. We assessed current evidence for gum chewing and gut function. Study design  All randomized controlled trials (RCTs) between 1990 and 2008 comparing gum chewing with controls/placebo were analyzed irrespective of language, blinding, or publication bias. The Jadad scale was used to assess study quality. Endpoints were time to flatus/feces, postoperative complications, and hospital stay. Random and fixed models were employed to aggregate study endpoints and assess heterogeneity. Results  Six RCTs containing 256 patients were included. Significant heterogeneity was identified and random effects model was employed. Heterogeneity may be explained through variations in delivery of surgical care. Significant reductions in the time to flatus and time to feces were identified but no significant difference in hospital or in-hospital postoperative complications were found. Conclusions  Gum chewing significantly reduced time to flatus and feces; however, hospital stay and postoperative complications were not reduced. Significant study heterogeneity means that these results should be interpreted with caution. Presentation to European Society of Coloproctology Annual Scientific Meeting Malta September 2007 Presentation to West of Scotland Surgical Association Annual Scientific Meeting October 2007     

Difference in the Burst Patterns of Digastric and Mylohyoid Activities during Feeding in the Freely Behaving Rabbit

Burst patterns in the digastric, mylohyoid, and masseter muscles and the resultant jaw movement orbits during chewing and swallowing were investigated in the freely behaving rabbit. Activities in the posterior mylohyoid fibers consisted of two continuous bursts. Peaks in the first burst of the posterior fibers occurred in the middle part of opening and preceded the digastric burst. Peaks in the second burst occurred in the final part of opening and coincided with those in the working side of the digastric burst. After removal of the bilateral digastric muscles, the gape size during chewing was largely reduced in the final part of opening and in the early part of closing. The results suggest that (a) the digastric may have a role in opening the mandible widely beyond the rest position but may not have a major role in the control of the horizontal (mediolateral) jaw movement, (b) the posterior mylohyoid fibers may have a function as an elevator of the tongue in the early part of opening, and (c) the posterior mylohyoid fibers may have a function as a depressor of the jaw in the late part of opening. Electromyographic burst in the mylohyoid muscle began with marked activity in the mid-closing phase. The results support a role for the mylohyoid muscle as a leading muscle of swallowing. Swallowing events in the rabbit are easily distinguished from the activities of the mylohyoid muscle and the thyrohyoid muscle.     

Engineering of polymer–surfactant nanoparticles of doxycycline hydrochloride for ocular drug delivery

Abstract

Context: Physiologic barriers of the eye, short precorneal drug residence time and poor corneal penetration are the few reasons for reduced ocular bioavailability.

Objective: This study was aimed to develop novel polymer–surfactant nanoparticles of hydrophilic drug doxycycline hydrochloride (DXY) to improve precorneal residence time and drug penetration.

Materials and methods: Nanoparticles were formulated using emulsion cross-linking method and the formulation was optimized using factorial design. The prepared formulation was characterized for particle size, ζ potential, encapsulation efficiency, in vitro drug release and ex vivo drug diffusion studies. The antibacterial activity studies were also carried out against Escherichia coli and Staphylococcus aureus using the cup-plate method. In vivo eye irritation study was carried out by a modified Draize test in rabbits.

Results and discussion: The particle size was found to be in the range of 331–850?nm. About 45–80% of the drug was found to be encapsulated in the nanoparticles. In vitro release demonstrated sustained release profile. Lower flux values in case of nanoparticles as compared to DXY pure drug solution in ex vivo diffusion studies confirmed the sustained release. The nanoparticles were found to be significantly effective (p?<?0.001) than DXY aqueous solution due to sustained release of doxycycline from nanoparticles in both the E. coli and S. aureus strains. The formulation was found to be stable over entire stability period.

Conclusion: The developed formulation is safe and suitable for sustained ocular drug delivery.     

Protecting effect of caffeine against vinblastine (an anticancer drug) induced genotoxicity in mice

Vinblastine a DNA non-intercalating agent has wide application against several human neoplasms, and found to cause cytogenotoxicity. In this study, clastogenotoxicity of vinblastine (1.5?mg/kg b w) and its prevention by caffeine at different doses (25, 50 and 100?mg/kg b w) administered intraperitoneally was assessed in in vivo mice. It was found that micronucleus level had decreased significantly (up to 28.8%) in 100?mg caffeine treated group at 30?h post treatment. However, it did not exhibit protective effect against chromosomal aberration in spaermatogonial cells at 24?h post treatment. The frequencies of aberrant primary spermatocytes had decreased significantly in 25 and 100?mg caffeine at 4th week of post treatment. Similarly, in 100?mg of caffeine administered, abnormal sperm level had reduced (4.01%) significantly at 8th week post treatment. Thus, caffeine decreased the vinblastine induced chromosomal aberrations and mitotic index in bone marrow cells. In conclusion, this study shows that caffeine exerts protective effect against vinblastin induced cytogenotoxicity. Further studies on molecular mechanism are interesting in order to develop it as an effective drug in cancer chemotherapy.     

In vitro and in vivo ocular safety and eye surface permanence determination by direct and Magnetic Resonance Imaging of ion-sensitive hydrogels based on gellan gum and kappa-carrageenan

Gellan gum, kappa-carrageenan and alginates are natural polysaccharides able to interact with different cations that can be used to elaborate ion-activated in situ gelling systems for different uses. The interaction between fluid solutions of these polysaccharides and cations presents into the tear made these biopolymers very interesting to elaborate ophthalmic drug delivery systems. The main purpose of this study is to evaluate the ability of mixtures of these polymers to obtain ion-activated ophthalmic in situ gelling systems with optimal properties for ocular use. To achieve this purpose different proportion of the biopolymers were analyzed using a mixture experimental design evaluating their transparency, mechanical properties and bioadhesion in the absence and presence of simulated tear fluid. Tear induces a rapid sol-to-gel phase transition in the mixtures forming a consistent hydrogel. The solution composed by 80% of gellan gum and 20% kappa-carrageenan showed the best mechanical and mucoadhesive properties. This mixture was evaluated for rheological behavior, microstructure, cytotoxicity, acute corneal irritancy, ex-vivo and in vivo ocular toxicity and in vivo corneal contact time using Magnetic Resonance Images (MRI) techniques. Result indicates that the system is safe at ophthalmic level and produces an extensive ocular permanence higher than 6 h.     

Bioadhesive vaginal drug delivery of nystatin using a derivatized polymer: Development and characterization

Increasing incidence of resistance to azole antifungals has highlighted the importance of the use of alternative therapeutic agents such as nystatin for the treatment of vulvovaginal candidiasis. The aim of the present study was to develop and characterize locally acting, film formulation for the treatment of candidiasis using a derivatized natural polymer. Derivatization of natural polymer was carried out in order to introduce anionic character to an otherwise neutral polymer, so as to enhance its interaction with vaginal mucous membrane along with inheriting the biocompatibility and nonirritant characteristics of its parent polymer. A carboxymethyl derivative of fenugreek gum (CMFG) was prepared, and characterized by DSC, FTIR and X-ray diffraction studies. The derivatized gum was found to possess bioadhesive and film forming properties. A 3² factorial design was employed to formulate vaginal films and a response surface methodological approach was used to study the effect of formulation variables on film properties. Films containing 5% w/v polymer and 2% v/v glycerol exhibited optimum properties in vitro. The optimized drug loaded formulation was able to release 100% drug over a period of 5 h and followed Korsmeyer–Peppas kinetics. It was found to be non-irritant and nontoxic to vaginal mucosa and showed appropriate antifungal properties in vivo.     

Effects of guar gum supplementation on the lipid profile: A systematic review and meta-analysis of randomized controlled trials

Background and aimsGuar gum can be used as an adjuvant in the treatment of dyslipidemia. However, based on data from different studies, the effectiveness of this product is not uniform. Therefore, we conducted a dose–response meta-analysis between guar gum supplementation and lipid profile.Methods and resultsFive databases (Scopus, Web of Science, PubMed/Medline, Embase, and Google Scholar) were searched to identify relevant articles published up to July 2020. The weighted mean difference (WMD) was derived based on the random-effects model. Overall findings were generated from 25 eligible trials. Patients’ conditions included hyperlipidemia, diabetes, metabolic syndrome, hypertension, overweight, carotid endarterectomy, and menopausal women. Prescribed gum dose varied between 100 mg/d and 30 g/d for 1–24 months. Compared with control groups, guar gum supplementation decreased total cholesterol (TC) by −20.41 mg/dL (95% CI: −26.76 to −14.07; P < 0.001) and low-density lipoprotein-cholesterol (LDL-C) by −17.37 mg/dL (95% CI: −23.60 to −11.13; P < 0.001), but did not change triglycerides (TG) (WMD: −6.53 mg/dL, 95% CI: −16.03 to 2.97; P = 0.178) and high-density lipoprotein-cholesterol (HDL-C) (WMD: −0.62 mg/dL, 95% CI: −1.68 to 0.44, P = 0.252).ConclusionsGuar gum supplementation significantly reduced serum LDL-C and TC levels in patients with cardiometabolic problems, but had neutral effects on TG and HDL-C levels.