壳聚糖在眼科疾病治疗中的应用

壳聚糖,是一种生物学性优良的多糖类化合物,具有无毒性、生物降解性、组织相容性、理化性质稳定等特性。本文就壳聚糖作为人工泪液、医用粘弹剂、药物缓释系统载体、抗纤维增生药物等的应用进行简要的介绍。     

Laser tissue welding in ophthalmic surgery

Laser welding of ocular tissues is an alternative technique or adjunct to conventional suturing in ophthalmic surgery. It is based on the photothermal interaction of laser light with the main components of the extracellular matrix of connective tissues. The advantages of the welding procedure with respect to standard suturing and stapling are reduced operation times, lesser inflammation, faster healing and increased ability to induce tissue regeneration. The procedure we set up is based on the use of an infrared diode laser in association with the topical application of the chromophore Indocyanine Green. Laser light may be delivered either continuously or in pulses, thus identifying two different techniques that have been applied clinically in various types of transplants of the cornea. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

A review of allograft ophthalmic tissue in eye surgery

Transplanting human tissue to the front of the eye has been practiced for over 100 years. Contiguous corneal layers may be transplanted separately (lamellar keratoplasty) or together (full thickness or penetrating keratoplasty). The former methods are gaining in popularity, replacing full thickness transplants. Reasons for transplantation and current practice and techniques are described with respect to their impact on vision, and associated adverse events.     

Optimal patch use in a stochastic environment

This paper considers an animal foraging on prey which are distributed in well-defined patches. It is assumed that the environment may be stochastic and that the animal can gain information on patch type as it forages. The foraging policy which maximises mean reward rate for the environment is characterised in terms of a function of state called the potential function. This policy is shown to be given by the rule: continue foraging on the present patch while the potential is positive, when the potential falls to zero move on to the next patch. Let r denote the current reward rate on a patch and let γ denote the maximum mean reward rate for the environment. It is shown that r ? γ if it is optimal to leave. Conditions which ensure r < γ are also given. For a large class of environments the optimal policy is stated in terms of a revised reward rate r?, and is given by the rule: continue on the present patch while $\text{r}\text{?}\text{> γ}$, when r? falls to γ move on to the next patch. Finally, it is shown that the stay time on a patch is a decreasing function of γ.     

The use of miniplates in craniomaxillofacial surgery

Miniplates were used in craniomaxillofacial surgery for fixation in the skull, maxilla, and/or mandible in 74 patients with minimal or no intermaxillary wiring. Procedures included forehead and orbital repositioning, frontofacial advancement, Le Fort III and particularly Le Fort I osteotomies, as well as mandibular osteotomies and fracture repair. The miniplates provided stable fixation and, compared with other techniques, improved airway safety. The complication rate was low: there were no infections, but two plates (1 percent) became exposed in the buccal sulcus. Although application of miniplates lengthened surgery and increased the cost of the procedure, the savings in intensive care monitoring more than offset these costs. The stability of fixation minimizes the opportunity to reposition the fragments postoperatively with training elastics. Therefore, meticulous technique is mandatory, with particular emphasis on passive fitting of the plates and precise drilling of screw holes.     

Complications of regional anesthesia for ophthalmic surgery.

Ocular regional anesthesia can be accomplished with either a peribulbar or retrobulbar approach. Each has advantages and disadvantages. Complications can be vision-threatening or life-threatening. Positioning the eye in neutral gaze when retrobulbar block is executed and using a needle no longer than 31 mm are effective strategies to reduce the incidence of serious complications.     

The natural histidine-containing dipeptide Nalpha-acetylcarnosine as an antioxidant for ophthalmic use

The naturally occurring compound Nalpha-acetylcarnosine is proposed as a prodrug of L-carnosine that is resistant to enzymatic hydrolysis by carnosinase. Eyes of rabbits were treated with 1% Nalpha-acetylcarnosine, L-carnosine, or placebo and extracts of the aqueous humor from the anterior eye chamber were analyzed for imidazole content by reverse-phase analytical high performance liquid chromatography (HPLC) and thin-layer (TLC) and ion-exchange chromatographic techniques. Topical administration of pure L-carnosine to the rabbit eye did not lead to accumulation of this compound in the aqueous humor over 30 min in concentration exceeding that in the placebo-treated matched eye. Nalpha-Acetylcarnosine showed dose-dependent hydrolysis in its passage from the cornea to the aqueous humor, releasing L-carnosine after l5-30 min of ocular administration of the prodrug in a series of therapeutic modalities: instillation < or = subconjunctival injection < or = ultrasound-induced phoresis. Different treatment techniques showed excellent toleration of 1%Nalpha-acetylcarnosine by the eye. Once in the aqueous humor, L-carnosine might act as an antioxidant and enter the lens tissue when present at effective concentrations (5-l5 mM). The advantage of the ophthalmic prodrug Nalpha-acetylcarnosine and its bioactivated principle L-carnosine as universal antioxidants relates to their ability to give efficient protection against oxidative stress both in the lipid phase of biological membranes and in aqueous environments. Nalpha-Acetylcarnosine is proposed for treatment of ocular disorders that have a component of oxidative stress in their genesis (cataracts, glaucoma, retinal degeneration, corneal disorders, ocular inflammation, complications of diabetes mellitus, and systemic diseases).     

The use of human deceased donor skin allograft in burn care

Burns are tissue wounds caused by thermal, electrical, chemical cold or radiation injuries. Deep injuries lead to dermal damage that impairs the ability of the skin to heal and regenerate on its own. Skin autografting following burn excision is considered the current gold standard of care, but lack of patient’s own donor skin or unsuitability of the wound for autografting may require the temporary use of dressings or skin substitutes to promote wound healing, reduce pain, and prevent infection and abnormal scarring. These alternatives include deceased donor skin allograft, xenograft, cultured epithelial cells and biosynthetic skin substitutes. Allotransplantation is the transplantation of cells, tissues, or organs, sourced from a genetically non-identical member of the same species as the recipient. Human deceased donor skin allografts represent a suitable and much used temporizing option for skin cover following burn injury. The main advantages for its use include dermoprotection and promotion of reepithelialisation of the wound and their ability to act as skin cover until autografting is possible or re-harvesting of donor sites becomes available. Disadvantages of its use include the limited abundance and availability of donors, possible transmission of disease, the eventual rejection by the host and its handling storing, transporting and associated costs of provision. This paper will explore the role of allograft skin in burn care, defining the indications for its use in burn management and the future potential for allograft tissue banking.     

Optimal patch use and metapopulation dynamics

Summary We compared the metapopulation dynamics of predator—prey systems with (1) adaptive global dispersal, (2) adaptive local dispersal, (3) fixed global dispersal and (4) fixed local dispersal by predators. Adaptive dispersal was modelled using the marginal value theorem, such that predators departed patches when the instantaneous rate of prey capture was less than the long-term rate of prey capture averaged over all patches, scaled to the movement time between patches. Adaptive dispersal tended to stabilize metapopulation dynamics in a similar manner to conventional fixed dispersal models, but the temporal dynamics of adaptive dispersal models were more unpredictable than the smooth oscillations of fixed dispersal models. Moreover, fixed and adaptive dispersal models responded differently to spatial variation in patch productivity and the degree of compartmentalization of the system. For both adaptive dispersal and fixed dispersal models, localized (stepping-stone) dispersal was more strongly stabilizing than global (island) dispersal. Variation among predators in the probability of dispersal in relation to local prey density had a strong stabilizing influence on both within-patch and metapopulation dynamics. These results suggest that adaptive space use strategies by predators could have important implications for the dynamics of spatially heterogeneous trophic systems.     

The use of venous allografts in vascular surgery

Biochemical, morphological and biomechanic study of various veins which were taken from 54 patients without trophic disorders during phlebectomy and kept for 7 days was made. 2% solution of neutral formalin and isotonic buffer solution (Henx solution) was used; results of the study show, that conserved veins can be used for grafting in arterial reconstructive surgery in cases of absence of autogenous vein material. Optimal period of conservation is 1 day.     

The use of modified sutures in plastic surgery

SUMMARY: Modified sutures have been developed and are currently being used in closed and open facial rejuvenation procedures. In addition, these sutures have applications in body contouring procedures and wound closure. The indications and efficacy of these sutures continue to evolve.     

瑞芬太尼复合丙泊酚静脉全麻与异氟醚吸入全麻在小儿眼科手术中比较

目的：比较瑞芬太尼复合丙泊酚静脉全麻用于小儿眼科手术麻醉的安全性、有效性及可控性。方法：选择择期眼科手术的小儿40例,随机分为两组：瑞芬太尼复合丙泊酚静脉全麻组（RP组）和异氟醚吸入全麻组（Ⅰ组）,每组20例。麻醉诱导采用咪唑安定0．05mg·kg^-1,丙泊酚2mg·kg^-1,维库溴胺0．1mg·kg^-1,观察组用瑞芬太尼2μg·kg^-1,对照组用芬太尼3μg·kg^-1,气管插管后机械通气,RP组麻醉维持采用静脉持续输注瑞芬太尼0．1μg·kg^-1min^-1和丙泊酚,Ⅰ组麻醉维持用异氟醚吸入,术中根据麻醉深度调整异氟醚吸入浓度和丙泊酚输注速度。观察围术期两组血流动力学变化、自主呼吸恢复、气管拔管和清醒的时间,苏醒后躁动和恶心呕吐的发生率。结果：两组病人平均动脉压（MAP）变化：两组T1、T2、T3、T4与T0比较,MAP明显降低（P〈0．05）,T5与T0比较,MAP无明显差异（P〉0．05）;组间比较,两组在T0、T1、T2、T3、T4、T5点,MAP无明显差异（P〉0．05）。两组病人心率（HR）变化：Ⅰ组：T3、T4、T5与T0比较,心率显著增快（P〈0．05）,RP组：T1、T2、T3、T4与T0比较,心率明显降低（P〈0．05）,T5与T0比较,心率变化无明显差异（P〉0．05）。组间比较,两组在T0心率无明显差异,T1、T2、L、T4、T5观察组与对照组比较,心率明显降低（P〈0．01）。麻醉苏醒时间比较：RP组与Ⅰ组比较,病人自主呼吸恢复时间、意识恢复时间和拔管时间均明显缩短（P〈0．05）。RP组术后躁动、恶心呕吐发生率,均低于Ⅰ组（P〈0．05）。结论：瑞芬太尼复合丙泊酚静脉全麻可为小儿眼科手术提供稳定血流动力学状态,快速苏醒,适用于小儿眼科手术麻醉。     

The use of conspecific reproductive success for breeding patch selection in terrestrial migratory species

Classical models of breeding habitat selection rarely deal with the question of information gathering for patch quality assessment. In this paper, we present two models comparing the fitness outcomes of behavioural strategies based on conspecific reproductive success as a cue to assess local environmental quality before selecting a new breeding habitat. The models deal with two phases of the life-cycle of a territorial migratory species: recruitment to a breeding population (model 1) and breeding site fidelity of subsequent breeding attempts (model 2). The first model shows that prospecting breeding patches before recruiting is the best strategy if the environment is predictable and contains a low proportion of good patches, even if it implies losing a breeding opportunity. The second model shows that dispersing after a breeding attempt according to the patch's breeding success rather than the individual's own success is the bests own success is the best strategy if the environment is patchy. These results underline the importance of studying the spatio-temporal variations of factors affecting reproductive success when considering the importance of habitat selection strategies based on conspecifics. Moreover, they allow the understanding of individual behaviour patterns observed in natural populations and their potential consequences at the metapopulation level.     

Rheology of sodium hyaluronate saline solutions for ophthalmic use

The aim of this work was to investigate the rheological properties of different saline solutions of sodium hyaluronate (NaHA) with special interest for medical applications. The experimental results were compared with literature data for commercial ophthalmic viscosurgical devices (OVDs) used in cataract surgery. We offer some tools to tailor the rheological behavior of OVDs for different purposes. We have investigated to which extent surgical requirements can be fulfilled by adjusting either the molecular weight of NaHA or its concentration, parameters that are in some respects equivalent but not in others. Furthermore, we demonstrate that moduli and complex viscosities of NaHA saline solutions are adequately falling on master curves, using either empirical or calculated shift factors, the latest ones being based on a modified Rouse model.