Many aspects of the biology and effective therapy of proliferative scars remain undefined, in part due to a lack of an accurate, practical, reproducible, and economical animal model for systematically studying hypertrophic scars. This study was designed to investigate whether hypertrophic scar formation could be induced in guinea pigs by removal of the panniculus carnosus alone, and by a combination of the removal of the panniculus carnosus with application of coal tar afterwards. Whole thickness skin excision or deep partial thickness injury was used to create the lesions on intact skin. Different anatomic locations were tested in different groups. Scars thus developed were examined morphologically by light microscopy and electron microscopy (TEM and SEM) and biochemically by measuring the activity of glucose-6-phosphate dehydrogenase (G6PD) to check whether these scars had morphological and biochemical properties specific to hypertrophic scars. The albino guinea pigs used in this study were divided into three groups. Removal of the panniculus carnosus was performed from the ventral aspect of the torso in animals in groups I and II. On the skin overlying the area of panniculectomy, circular skin excision was performed in group I, and deep partial thickness burn injury was inflicted in group II, to see whether wounds would heal with hypertrophic scars. In group III, dorsal aspect of the torso were used and wounds were produced by circular skin excisions followed by panniculectomy on both sides but coal tar was applied to only one side. Tissue samples were taken from the scars that were hypertrophic in appearance, and from normal scars and normal skin for comparison. Light and electron microscopic examinations and G6PD activity measurements were performed on these samples. While hypertrophic scar development was not seen in group I and group II, scars with morphological and biochemical properties specific to hypertrophic scars developed in one third of animals in group III after healing of the wounds treated with coal tar. In conclusion, it is shown that it is possible to develop experimental hypertrophic scars in guinea pigs with morphological and biochemical properties similar to those of human proliferative scars. Therefore this model is a new, practical, and economical experimental animal model to study proliferative scars, although improvements are needed to increase yield.
Surgical procedures for correction of craniofacial deformities resulted in unavoidable and extensive blood loss in small children and infants. Almost all of the patients undergoing these procedures will undergo a blood transfusion either during or immediately after the operation. A retrospective review of 30 patients who underwent craniofacial surgery was performed in this study to determine the magnitude of transfusion required for craniofacial surgery, document transfusion morbidity, and identify variables associated with the transfusion. The mean estimated blood loss was 566.8 mL, the mean intraoperative transfusion was 394.8 mL, the mean postoperative transfusion was 103.2 mL, and the mean total transfusion was 505 mL. The mean operative time was 450 minutes, the mean preoperative hemoglobin and the mean postoperative hemoglobin before hospital discharge were 11.6 g/dL and 10.3 g/dL, respectively. Craniofacial surgical procedures involve extensive scalp dissection and calvarial and facial bone osteotomies in patients with a low total blood volume. Every medical and surgical strategy for minimizing the need for blood transfusion should be considered.
Extravasation of vesicant antineoplastic agents such as doxorubicin into the skin or subcutaneous tissues may result in loss of the full thickness of the skin or underlying structures. Several treatment methods have been advocated but none has demonstrated any superiority to the others. The authors designed a controlled animal study in 88 rats to test three methods of early treatment of extravasation of the vesicant antineoplastic agent doxorubicin. The first step of the study included 48 Sprague-Dawley rats. All animals received intradermal injections of 1 mg doxorubicin superficially to the panniculus carnosus in the dorsum. The rats were then divided into four groups of 12 rats each, as follows: group 1, no treatment; group 2, immediate intradermal injection of 0.1 ml saline to the same site; group 3, immediate intradermal injection of 10 microg granulocyte macrophage-colony stimulating factor (GM-CSF) in 0.1 ml saline to the same site; group 4, immediate intradermal injection of 10 microg granulocyte-colony stimulating factor (G-CSF) in 0.1 ml saline to the same site. During the next 6 weeks the rats were observed for the development of necrosis. Ulcers developed and reached maximum size two weeks after the injections. The largest ulcers according to area were observed in group 1 and the mean value was 21.25 mm (p < 0.05). Although wound areas were significantly smaller in the saline group than in the control group and the mean value was 7.58 mm (p < 0.05), the smallest lesions were observed in groups 3 and 4, and the mean values were 1.08 mm and 0.83 mm respectively (p < 0.05). There was statistically no difference with regard to mean ulcer area between groups 3 and 4. During the second step of the experiment, the remaining 40 Sprague-Dawley rats were used. Groups containing 10 rats each were designed similarly after all animals received intradermal injections of 1 mg doxorubicin into the back. On the 10th day after the injection, the entire area of the ulcer together with the underlying panniculus carnosus was excised for pathological examination and for determination of glucose 6-phosphate dehydrogenase (G6PD) activity. On microscopic examination, the extravasated ulcer consisted of a large area of ischemic necrosis. There was marked damage to small blood vessels in the form of fibrinoid necrosis and vasculitis. Injured vessel counts were higher in the control group (group 1; p < 0.05). No difference was observed in G6PD activity between the groups. The authors conclude that both saline and tissue growth factors (GM-CSF and G-CSF) are useful for the early treatment of doxorubicin extravasation; however, GM-CSF and G-CSF are more beneficial.
Despite the fact that cyanoacrylates, a group of rapidly polymerizing adhesives, are used widely in general surgery, neuroradiology, otolaryngology, and plastic surgery, scientific data on histopathological changes resulting from the deposition of -butyl-2-cyanoacrylate (NBCA), a new-generation cyanoacrylate derivative, in human tissues is based largely on experimental observations in animals and sporadic postmortem studies in humans. The authors report the consecutive pathological findings of a patient who underwent surgery for facial hemangioma after percutaneous injection of NBCA for devascularization of a lesion, and underwent additional surgery 1 and 6 months after the initial operation for the removal of the residual NBCA cast from the injection site. Acute inflammatory findings after injection of NBCA and the development of a chronic granulomatous foreign body reaction support the histological findings of experimental animal studies and postmortem examinations on humans. Additionally, their findings support the proposed hypothetical sequence of events for the recanalization of cyanoacrylate-embolized vascular structures.
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