Evaluation of the photocontact allergenic potential of 6-methylcoumarin in the guinea pig

6-Methylcoumarin was tested in a new animal model developed for the predictive evaluation of photocontact allergenic potential. Negative results were obtained and these are discussed with respect to inherent limitations of the animal model.     

羟基脲致下肢溃疡一例

报告1例由羟基脲不良反应引起的下肢溃疡。患者女,82岁,既往原发性血小板增多症15年,长期口服羟基脲治疗。5年前出现下肢溃疡。查体可见双踝周多发性浅溃疡伴网状色素减退,周围皮肤肿胀。诊断:下肢溃疡(羟基脲不良反应)。给予布洛芬缓释胶囊、盐酸莫西沙星片口服,生理盐水、硫酸阿米卡星注射液、地塞米松磷酸钠注射液混合后外用,溃疡创面基本愈合,伴白色萎缩。     

A new animal model for contact dermatitis: the hairless guinea pig.

Allergic and irritant contact reactions were evaluated in the recently identified hairless guinea pig, Crl:IAF(HA)BR, a mutant from the Hartley strain. The cutaneous changes were observed macro- and microscopically. The irritant contact dermatitis was induced by croton oil, 2,4-dinitrochlorobenzene (DNCB), or anthralin. Both hairless and hairy guinea pigs developed similar reactions to these chemicals. The density of the epidermal Langerhans cells (LC) of hairless guinea pigs was significantly higher than that in the hairy strain. Allergic contact sensitization was easily induced with DNCB. Photoallergic contact sensitization was also induced with tetrachlorosalicylanilide (TCSA) but not with tribromosalicylanilide (TBS). However, by administration of cyclophosphamide before sensitization, positive photocontact responses were seen with TBS. These results indicate that hairless guinea pigs can be used as animal models for investigation of immunologic and nonimmunologic contact reactions.     

深部克柔念珠菌感染豚鼠模型的建立及致病性初步研究

目的建立深部克柔念珠菌感染的豚鼠模型,并对其进行致病性研究。方法采用皮下注射曲安奈德和腹腔注射环磷酰胺诱导豚鼠进入免疫抑制状态后,静脉注射克柔念珠菌悬液,使豚鼠发生深部克柔念珠菌感染;与免疫正常组(对照组)豚鼠比较,观察两组死亡情况和脏器的组织载菌量,并进行统计学分析。结果免疫抑制组(实验组)豚鼠的死亡从感染后1d开始,3～4d达到高峰,至第6天止,其死亡率是正常组的10倍(P<0.01);各脏器的组织载菌量明显高于对照组(P<0.05);在检查的4种脏器中,最为易感的是肾脏,最不易感的是肝脏,各脏器间易感的差异有显著性(P<0.01)。结论本实验能有效诱导豚鼠的免疫抑制状态,明显增加豚鼠体内发生深部克柔念珠菌感染的概率;豚鼠的死亡率和组织载菌量是客观反映豚鼠体内真菌感染情况的敏感观察指标。用上述方法成功建立的深部克柔念珠菌感染豚鼠模型可用于后续抗真菌药体内抗真菌活性的研究。     

Evaluation of electrical stimulation for ischemic wound therapy: a feasibility study using the lapine wound model

Chronic wounds are a major secondary complication for many people with impaired mobility. Electrical stimulation (ES) has been recommended as a adjunctive therapy, however optimal treatment paradigms have not been established. Our group seeks to determine the basic mechanisms underlying ES wound therapy, an area where understanding is currently limited. A feasibility study was carried out to develop the Ahn/Mustoe lapine wound model for systematic investigation of the effects of electrical stimulation on ischemic wound therapy. A standardized surgical procedure incorporated a hybrid stimulation system comprising an implantable mini-stimulator and surface electrodes, with creation of repeatable ischemic wounds. Twenty mature male New Zealand white rabbits (3 kg weight) were employed to evaluate the effects of two empirically selected stimulation paradigms applied continuously for 7–21 days, using each animal as its own control. Outcomes measures included transcutaneous blood gas levels, histology, total RNA content and analysis of α2 (I) collagen (COL-I), type IV collagen (COL-IV), α1 (V) collagen (COL-V), and vascular endothelial growth factor (VEGF) expression using real-time quantitative PCR. All markers for stimulated wounds showed increased activity relative to non-stimulated control wounds between 7 and 14 days following injury, with peak activity at 14 days. By 21 days post-injury, all activity had returned to near baseline level. VEGF and COL-IV levels were found to be significantly higher for pattern A (110 μs pulse width) compared to pattern B (5 μs pulse width) at 14 days, implying that pattern A may be more effective at promoting angiogenesis. All wounds were fully re-epithelialized by 10 days post-injury. Both COL-I and COL-V showed statistically significant (P < 0.05) increased activity between day 7 and day 14 for pattern A, potentially indicating a continued effect on matrix remodeling. The early closure of all wounds implies that the rabbit ear model may not be valid for chronic wound studies.     

The guinea pig as a model for predicting photoallergic contact dermatitis

This report describes modifications in the techniques used for both the induction and elicitation of photoallergic contact dermatitis (PACD) in the guinea pig. These changes have improved the reliability of this animal as the model of choice for screening chemicals or products for (heir tendency to produce PACD.
The induction period consists of 15 exposures of the test substance to shoulder skin that has been abraded with a nylon brush rotating at 13,000 rpm. One hour later, the KM site is irradiated with broadband UVA from a source having some irradiance below 320 nm (UVA/b). The animals receive 450 J/cm² of UVA during the three-week induction period. The elicitation (challenge) test is repeated fur two consecutive days. Each day, the test material, if a liquid, is applied to two sties even 30 lo 60 min for 6 h; then one of the sites receives 20 J/cm² of UVA.
These photo-induction and photo-elicitation procedures have demonstrated that low-level concentrations (0.25% range) of 6-melhyl coumarin or musk ambrette will both induce and elicit PACD in the guinea pig. This report adds more evidence that the induction of PACD in the guinea pig is dependent on broadband UVA.     

Quantitative and objective evaluation of wound debriding properties of collagenase and fibrinolysin/desoxyribonuclease in a necrotic ulcer animal model

Proteolytic enzymes have been used for wound debridement for many years. The two enzymes most widely used in Europe are fibrinolysin/desoxyribonuclease and collagenase. Despite their frequent use, very few placebo-controlled studies comparing the enzymes with vehiculum only, or with each other, are available. In a specially developed necrotic ulcer animal model, combined with a computer image analysis technique to measure necrotic and total wound surface areas quantitatively, we assessed the wound-cleansing properties of fibrinolysin/DNase oleogel, collagenase ointment, saline-soaked gauze control treatment, and new galenic formulations of collagenase, including placebos. The average relative area of necrotic tissue present in the wound after 1 week was 31% for collagenase ointment and 56% for fibrinolysin/DNAse oleogel ( P = 0.0037). Collagenase gel was significantly ( P = 0.0007) better in removing necrosis than placebo (gel only). Fibrinolysin/DNAse was not significantly more effective than the three placebo or control treatments (placebo film, placebo gel, saline-soaked gauzes). We conclude that collagenase is a suitable enzyme for wound debridement, but we were not able to detect clinical efficacy of fibrinolysin/DNAse in this model. Received: 5 September 1997 / Accepted: 14 November 1997     

Measurement of skin-fold thickness in the guinea pig

The rabbit has been used for decades for predictive testing of skin irritancy, but in recent years, the guinea pig has been suggested as an alternative, especially for assessment of one of the components of the irritant reaction: edema (fluid accumulation). A method based on skin-fold measurements with Harpenden calipers has been developed and modified. In previous papers, experience with sodium lauryl sulphate, nonanoic acid and industrial solvents was reported. The present results concern the use of cutting fluids, buffered and unbuffered acid and alkaline solutions, formalin and dimethyl sulfoxide. This inexpensive and comparatively unsophisticated method afforded clear dose-response relationships and good discriminating power. The only exception was the acid and alkaline solutions, where no changes in skin-fold thickness were observed despite their documented irritant potential. The appearance of erythema (visual scoring) and the increase in skin-fold thickness, and their relationship, are discussed with some illustrative examples. The method described is now well standardized and is suited for predictive testing of the edema-inducing capacity of chemicals and products.     

光动力学疗法对豚鼠光老化治疗作用的研究

目的探讨5-氨基酮戊酸(ALA)联合强脉冲光(IPL)的光动力学疗法(PDT)对豚鼠光老化模型的影响,并摸索合适的5-ALA治疗浓度。方法以模拟日光光源(SSR)建立豚鼠光老化模型,10%、20%5-ALA联合IPL治疗,每3周一次,共3次。观察真皮细胞外基质(胶原纤维、弹力纤维)的改变。结果豚鼠以亚红斑量SSR照射13周,光照部位真皮浅层出现了典型的光化性弹力纤维变性损害。经10%5-ALA联合IPL治疗后,上述改变明显改善,而20%5-ALA联合IPL可进一步加重损伤。结论光动力疗法对光老化有一定改善作用,选择合适的5-ALA治疗浓度很重要。     

生精障碍动物模型研究进展

男性不育的发病率在近些年来呈现上升的趋势。在男性不育的患者中,很大一部分为特发性不育,大多表现为无明确病因的少精、无精子症。通过建立理想的生精障碍动物模型,有助于研究男性不育的发病机制,并为临床上的诊治提供帮助。本文对国内外学者通过不同方法建立的生精障碍动物模型进行了综述。     

The regeneration of substance P-containing nerve fibers in the process of burn wound healing in the guinea pig skin

The regeneration of substance P (SP)-containing nerve fibers in the process of burn wound healing in the guinea pig skin has been studied by immunohistochemistry. SP-like immunoreactivity, which was specifically localized in neural elements of intact skin, was found to disappear in the burn wound including its margin on day 2 post burn. The SP-containing nerve fibers were first detected in periods later than day 2 post burn, and the regeneration seemed to occur in association with regeneration of blood vessels at the wound margins. These nerve fibers gradually increased in number and acquired maximum density on day 14 post burn. In addition, such renewed fibers showed sprouting to form a dense network, which has never been observed in intact skin, in the upper granulation tissue just beneath the regrowing epidermis. Following that peak period, the density of the fibers gradually decreased to less than that of controls. The characteristic process of regeneration of SP-containing nerve fibers, having a peak period of fiber density at least in burn wound healing, appeared similar to that of the regeneration of sympathetic catecholaminergic nerve fibers reported previously.     

槲皮素和原花青素对豚鼠白癜风模型黑素合成的影响

目的：明确槲皮素、原花青素单体对白癜风豚鼠皮肤黑素合成的影响。方法：利用过氧化氢构建38例豚鼠白癜风模型成功后,随机分为5组,分别给予乙醇（A组）、蒸馏水（B组）、0.1%8-甲氧补骨脂素（8-MOP）（C组）、0.5%槲皮素（D组）、0.1%原花青素（E组）以及0.3%原花青素（F组）外涂皮肤,其中C组用药1h后予日光照射10min。治疗期间,每2周拍摄记录豚鼠皮损色素沉着。40天后,处死全部模型并取被试区皮肤。肉眼下及HE染色观察皮肤基本病理改变;黑素颗粒染色法（Fontana-Masson法）检测含黑素颗粒细胞数量。结果：除A、B组外,其余4组在治疗期间均出现不同程度色素沉着。HE染色发现,与A、B组相比,其余4组皮肤厚度更厚,色沉较明显。Fontana-Masson法显示,与A、B组相比,其余4组黑素颗粒明显增多（P均<0.05）,其中,D、F组明显多于E组（P均<0.05）。结论：槲皮素以及原花青素单体对白癜风豚鼠模型的皮肤具有复色作用。     

The linear excisional wound: an improved model for human ex vivo wound epithelialization studies

Background/purpose: Wound healing is a complex process that involves multiple intercellular and intracellular processes and extracellular interactions. Explanted human skin has been used as a model for the re‐epithelialization phase of human wound healing. The currently used standard technique uses a circular punch biopsy tool to make the initial wound. Despite its wide use, the geometry of round wounds makes it difficult to measure them reliably. Methods: Our group has designed a linear wounding tool, and compared the variability in ex vivo human linear and circular wounds. Results: An F test for differences in variances demonstrated that the linear wounds provided a population of wound size measurements that was 50% less variable than that obtained from a group of matched circular wounds. This reduction in variability would provide substantial advantages for the linear wound technique over the circular wound punch technique, by reducing the sample sizes required for comparative studies of factors that alter healing. Conclusion: This linear wounding tool thus provides a method for wounding that is standardized, provides minimal error in wound gap measurements, and is easily reproducible. We demonstrate its utility in an ex vivo model for the controlled investigation of human skin wounds.     

Hyperbaric oxygen attenuates apoptosis and decreases inflammation in an ischemic wound model

The molecular mechanisms whereby hyperbaric oxygen (HBO) improves ischemic wound healing remain elusive. In this study, a rat model of wound ischemia was used to test the hypothesis that HBO enhances wound healing by modulating hypoxia-inducible factor-1alpha (HIF-1alpha) signaling. Male Sprague-Dawley rats underwent creation of a previously validated ischemic flap. Three groups underwent daily treatment: HBO (90 minutes, 2.4 atm); systemic administration of the free radical scavenger, N-acetylcysteine (NAC 150 mg kg(-1) intraperitoneal); control (neither HBO nor NAC). HBO treatment improved healing of the ischemic wounds. Analysis of ischemic wound tissue extracts demonstrated significantly reduced expression of HIF-1alpha, p53, and BNip3. Additionally, HBO increased expression of Bcl-2 while decreasing cleaved caspase-3. DNA fragmentation was abolished and the number of TUNEL-positive cells was reduced compared to the other groups. Vascular endothelial growth factor, cyclooxygenase-2, and neutrophil infiltration were reduced in ischemic wounds treated with HBO. These results indicate that HBO improves ischemic wound healing by downregulation of HIF-1alpha and subsequent target gene expression with attenuation of cell apoptosis and reduction of inflammation.     

A local lymph-node assay validation study of a structure-activity relationship model for contact allergens

A structure-activity relationship model for prediction of contact allergenic potential of chemicals had previously been developed. The model had been shown to be able to classify known allergens and non-allergens using data on physicochemical and reactivity parameters of functional groups by discriminant two-value multiple regression analysis. To investigate the model, six selected chemicals which had not been previously investigated for allergenicity were studied with both the model and a murine local lymph-node assay. The same compounds were predicted to be allergens (3-bromo-2-coumaranone, 1-nitrocyclohexene and -acryloyloxy-, -dimethyl--butyrolactone) and non-allergens (1-carbethoxy-4-piperidone, 6,7-dimethoxy-2-tetralone and 9-acetylanthracene) by both the model and the local lymph-node assay.