Nanomaterials as matrices for enzyme immobilization

Nanomaterials constitute novel and interesting matrices for enzyme immobilization. While their high surface to volume ratio is an obvious advantage, their Brownian motion can impact the behavior of enzymes immobilized on these matrices. Carbon nanotubes, superparamagnetic nanoparticles, and mesoporous materials constitute some important classes of matrices. Such immobilized enzyme systems have been used in both aqueous and low water media for biocatalysis and resolution of racemates. This overview examines the behavior of enzymes immobilized on nanomaterials and discusses the results reported with such biocatalyst preparations.     

Selective modulation of antioxidant enzyme activities in host tissues during Rickettsia conorii infection

The involvement of oxidative mechanisms in the pathogenesis of rickettsiosis was investigated using infection of C3H/HeN mice with sub-lethal and lethal infectious doses of Rickettsia conorii, the causative agent of Mediterranean spotted fever. Microscopic examination of tissues at 48 and 96 h post-infection revealed characteristic pathologic features and the presence of rickettsiae in the endothelium of infected tissues. Activities of key antioxidant enzymes, namely glutathione peroxidase, glutathione reductase, glucose-6-phosphate dehydrogenase, and superoxide dismutase, at these times exhibited a pattern of differential and selective modulation in brain, lungs, and testes of mice infected with viable organisms, whereas heat-inactivated or sonically disrupted rickettsiae had no effect. Of these, most significant changes were evident in the lungs of infected animals. Adaptive alterations in oxidant-scavenging enzymes occurred in apparent correlation with the dose and duration of infection. Treatment with an antioxidant, alpha-lipoic acid, protected against infection-induced oxidative injury via regulation of antioxidant enzyme activities and maintenance of reduced glutathione levels. These results suggest the involvement of regulatory enzymes of glutathione redox and superoxide scavenging systems in the antioxidant response during in vivo infection, the extent of which varies with the titer of viable rickettsiae in different organs of the host.     

Alpha-crystallin-incorporated collagen matrices as an aid for dermal wound healing

This study evaluated the effects of noncovalently incorporated crystallin into the collagen matrix for dermal wound-healing processes in rats. Crystallin-incorporated collagen matrix (CIC) showed better healing when compared to wounds treated with collagen matrix (CS) and without collagen (CR). Biochemical parameters and histological analysis revealed that increased wound contraction enhanced cell proliferation and efficient radical scavenging in the CIC group. The higher shrinkage temperature of CIC films when compared to CS groups suggested increased hydrothermal stability for the former material. An in vitro release study of CIC has showed sustained and time-dependent release of crystallin from the collagen matrix. These results demonstrate the possibility of using crystallin as therapeutic protein in the wound-healing process.     

生肌玉红胶原海绵修复创面损伤

背景：生肌玉红胶原海绵能显著促进创面愈合。 目的：观察生肌玉红胶原海绵对兔皮肤创面愈合的影响。 方法：在新西兰白兔背部制造3处全层皮肤缺损创面,分别以生肌玉红胶原海绵、贝复剂(重组碱性成纤维细胞生长因子外用溶液)、生理盐水修复。观察各组创面愈合时间、创面愈合率,检测创面修复组织内成纤维细胞数、血红素氧化酶1、转化生长因子β1 mRNA与蛋白及增殖细胞核抗原蛋白表达。 结果与结论：与贝复剂、生理盐水比较,生肌玉红胶原海绵可显著促进成纤维细胞增殖(P < 0.05),增加创面血红素氧化酶1、转化生子因子β1及增殖细胞核抗原的表达(P < 0.05),提高创面愈合率(P < 0.05),缩短创面愈合时间(P < 0.05)。证实生肌玉红胶原海绵能够促进创面修复,其作用机制可能是通过提高创面血红素氧化酶1、转化生长因子β1表达促进细胞增殖,增加成纤维细胞等创面修复细胞。     

Effects of chronic hypoxia and dietary restriction on myocardial enzyme activities.

Enzyme activities were measured in homogenates of left and right ventricles of guinea pigs after 14 and 28 days' exposure to 400 mmHg barometric pressure. All animals developed anorexia and right ventricular hypertrophy. Two control groups of animals were used, one free fed and the other restricted to the amount of food chosen by the hypobaric group. The factorial design of the experiment allowed some distinction between the effects of anorexia, hypertrophy, and hypoxia. Dietary restriction was associated with a decrease in glycogen phosphorylase, hexokinase, and succinate dehydrogenase activity and an increase in the M-subunits of lactate dehydrogenase. Myocardial hypertrophy was associated with an increase in the activity of the enzymes of the glycolytic pathway down as far as phosphoglycerate kinase and an increase in the M-subunits of lactate dehydrogenase. Chronic hypoxia seemed specifically to be associated with an increase in the H-subunits of lactate dehydrogenase and possibly a slight transient increase in succinate dehydrogenase activity. Mixing studies indicated that changes in enzyme activities were likely to be due to changes in enzyme concentrations.     

Quercetin incorporated collagen matrices for dermal wound healing processes in rat

We have been developing antioxidants incorporated collagen matrix as a novel biomaterial for various biomedical applications. In this study we made use of quercetin incorporated collagenous matrix for dermal wound healing in rat. Quercetin incorporated collagen (QIC) treated groups were compared with control and collagen (CS) treated animals. QIC treated animal showed a better healing when compared to control and CS treated wound. The biochemical parameters like hydroxyproline, protein, uronic acid content in the healing wound, revealed that there is an increase in proliferation of cells in quercetin treated groups when compared to CS group and there is considerable increase in wound contraction when compared to CS treated group. In addition we adapted the antioxidant assay using 2,2'-azobisisobutryonitrile (AIBN) to assess in vitro antioxidant activity of QIC. The antioxidant studies indicate QIC quench the radicals more efficiently. These results suggested that quercetin incorporated collagen matrix could be a novel dressing material for dermal wound healing.     

慢性溃疡创面床准备的疗效

目的 观察创面床准备埘慢性溃疡创而的疗效.方法 2000年9月至2005年4月本院本科室的107例慢性溃疡创面入选患者,随机分为试验组(n=58)和对照组(n=49).前者采用创面床准备方法 进行创面处理,对照组采用传统创而处理方法 ,比较两组患者的住院大数、组织病理变化、创面情况变化及手术失败率.结果 试验组的住院天数(35.1±26.8)d较对照组(49.7±32.9)d短(P<0.05).HE染色发现试验组创而组织变化朝有利于愈合的方向发展.试验组和对照组的换药后白愈率分别为26%(15/58)和10%(5/49)(P<0.05);植皮术手术失败率分别为9%(3/33)和23%(6/26)(P>0.05);皮瓣转移术失败率分别为0%(0/10)和44%(8/18)(P<0.05).结论 创而床准备方法 是慢性溃疡一种有效和科学的创面处理手段,可促进较小创面愈合.经创面床准备后选择手术覆盖创而可减少手术失败率,加快创面愈合.     

Functional modulation of shoulder girdle stability

We have previously reported that electrical stimulation of the ulnar nerve at group I strength evokes reflex excitation of the trapezius muscle in normal human subjects. In the present study this reflex has been evoked while subjects were performing a number of different tasks. When subjects performed a task involving a high degree of manual dexterity, the reflex was larger. On the other hand, when subjects performed a task that can be achieved with virtually no movement of the hand or wrist musculature, the reflex does not appear to show any task dependency. These results support the view that in delicate tasks of the hand, such compensatory reflexes are more important than in basic mechanisms such as lifting an object. The functional consequences of these findings and their significance in relation to the possibility that these task-related reflex gain changes produce intention tremor is discussed.     

Modelling of chronic wound healing dynamics

Following chronic wound area over time can give a general overview of wound healing dynamics. Decrease or increase in wound area over time has been modelled using either exponential or linear models, which are two-parameter mathematical models. In many cases of chronic wound healing, a delay of healing process was noticed. Such dynamics cannot be described solely with two parameters. The reported study deals with two-, three-, and four-parameter models. Assessment of the models was based on weekly measurements of 226 chronic wounds of various aetiologies. Several quantitative fitting criteria, i.e. goodness of fit, handling missing data and prediction capability, and qualitative criteria, i.e. number of parameters and their biophysical meaning were considered. The median of goodness of fit of three- and four-parameter models was between 0.937 and 0.958, and the median of two-parameter moels was 0.821 to 0.883. Two-parameter models fitted wound area over time significantly (p=0.001) worse than three- and four-parameter models. The criterion handling missing data provided similar results, with no significant difference between three- and four-parameter models. Median prediction error of two-parameter models was between 111 and 746; three-parameter models resulted in an error of 64 to 128, and finally four-parameter models resulted in the highest prediction error of 407 and 238. Based on the values of quantitative fitting criteria obtained, three parameters were chosen as the most appropriate. Based on qualitative criteria, the delayed exponential model was selected as the most general three-parameter model. It was found to have good prediction capability and in this capacity it could be used to help physicians choose the most appropriate treatment for patients with chronic wounds after an initial three-week observation period, when the median error increase of fitting is 74%.     

Biomimetic LBL structured nanofibrous matrices assembled by chitosan/collagen for promoting wound healing

This paper reports the fabrication of biomimetic nanofibrous matrices via co-electrospinning of polycaprolactone (PCL)/cellulose acetate (CA) and layer-by-layer self-assembly (LBL) of positively charged chitosan (CS) and negatively charged Type Ⅰ collagen on the nanofibrous matrix. FE-SEM images indicate that the average fiber diameter increased from 392 to 541 nm when the coating bilayers varied from 5 to 20.5. Besides, the excellent biocompatibility and enhanced attachment and spreading of normal human dermal fibroblasts (NHDFs) of prepared nanofibrous mats are confirmed by MTT and SEM results. Furthermore, the LBL structured (CS/collagen)_n nanofibrous mats greatly improve the cell migration in vitro, promote re-epithelialization and vascularization in vivo, and up-regulate the expression of collagen Ⅳ and α-tubulin, as well as the Integrin β1 and phosphorylation of focal adhesion kinase (FAK) at Tyr-397. The levels of expressed protein are significantly enhanced with increasing coating bilayers via immunohistochemistry and western blotting analyses. Collectively, these results suggest that the LBL structured biomimetic nanofibrous matrices may enhance cell migration and further promote the skin regeneration by up-regulating the secretion of ECM protein and triggering Integrin/FAK signaling pathway, which demonstrate the potential use of the nanofibrous mats to rapidly restore the structural and functional properties of wounded skin.     

Current status of genetic modulation of growth factors in wound repair

Growth factors are members of a large functional group of polypeptide regulatory molecules secreted by different cells. They are important players in orchestrating all stages of wound healing exerting their influence through autocrine and paracrine fashions within sites of injury and repair. They are mitogen, chemotactic, they regulate cell-cell interactions and influence synthesis and composition of extracellular matrix components. The use of growth factors to stimulate wound healing is a promising therapeutic approach to repair chronic tissue defects. The delivery of genetic material offers an attractive treatment modality to produce an appropriate amount of growth factor proteins within the wound site. Gene therapy might become a significant treatment modality for those wound healing pathologies refractory to other wound management approaches. This review discusses several methods of growth factor gene transfer into wound tissue.     

A comparison of tissue-engineered hyaluronic acid dermal matrices in a human wound model

The derivatives of hyaluronic acid (hyaluronan) have been extensively studied in the field of tissue engineering. Several forms of the material are available (benzyl esters of hyaluronic acid, HYAFF), with differing degradation profiles. This study compared 2 such products used for dermal regeneration (HYAFF p80 and HYAFF p100, the partial and total benzyl ester of hyaluronan, respectively), in a human model. In a prospective, randomized, controlled trial, 20 tattoos were tangentially excised and 1 of 2 hyaluronic acid-derived dermal matrices were applied to the wound bed. The partial ester was changed after 1 week and the total ester was kept for 2 weeks. After 2 weeks, cultured epidermal autograft was applied using the Laserskin method. Wounds were subsequently assessed by several modalities and by such features as rate of epithelialization, wound contraction, and histologic and immunohistologic appearances. Subtle differences were seen between the 2 groups, indicating that the total ester, which showed better clinical performance, could be used, especially in burns. This has the advantage of a single application for a 2-week period, rather than the comparison material, a partial ester, which requires weekly changing and degrades faster. Further, the method of epidermal grafting with a dermal substitute shows excellent results and adds to the armory for the treatment of both chronic and acute wounds.     

Autoantibodies to thyroid peroxidase in patients with chronic thyroiditis: effect of antibody binding on enzyme activities.

Using thyroid peroxidase (TPO), which was purified from the thyroid of patients with Graves' disease, we attempted to determine whether sera from patients with chronic thyroiditis contained antibodies to the enzyme. When the binding was tested by ELISA, sera from patients with chronic thyroiditis revealed high binding activities to TPO. When TPO was incubated with IgG from sera followed by treatment with protein A-Sepharose and centrifugation, the remaining TPO activities in the supernatant fraction were lower in most of the patients, as compared to normal controls. Moreover, IgG purified by DEAE-cellulose chromatography from sera in patients interfered with the TPO activities. Titres of anti-TPO antibodies correlated well with those of anti-microsome antibodies. These results indicate the presence of autoantibodies to TPO in sera of most patients with chronic thyroiditis and that TPO may be one component of microsome antigen complexes recognized by the autoantibodies. Studies on the inhibition of TPO by IgG isolated from sera of patients using guaiacol and iodide assays revealed that at least three epitopes of TPO molecule were recognized by autoantibodies and that the antigenic determinants on TPO molecule recognized by autoantibodies could be heterogeneous in patients.     

Glucose oxidase incorporated collagen matrices for dermal wound repair in diabetic rat models: a biochemical study

Impaired wound healing in diabetes is a well-documented phenomenon. Emerging data favor the involvement of free radicals in the pathogenesis of diabetic wound healing. We investigated the beneficial role of the sustained release of reactive oxygen species (ROS) in diabetic dermal wound healing. In order to achieve the sustained delivery of ROS in the wound bed, we have incorporated glucose oxidase in the collagen matrix (GOIC), which is applied to the healing diabetic wound. Our in vitro proteolysis studies on incorporated GOIC show increased stability against the proteases in the collagen matrix. In this study, GOIC film and collagen film (CF) are used as dressing material on the wound of streptozotocin-induced diabetic rats. A significant increase in ROS (p?相似文献   

Computer assisted evaluation of wound healing in chronic ulcers

The aim of this work was to present an efficient and objective method of wound healing assessment based on serial measurements of ulcer dimensions and calculation of wound margin advancement towards the center of the lesion. The method is implemented via computer software, which permits clinicians to perform necessary computations. The proposed method of wound assessment integrates pieces of work that have been published in the past into a user-friendly environment. The high accuracy of computations may help clinicians to make objective decisions in the management of difficult to heal ulcers.