Effect of obstructive jaundice on wound healing. An experimental study in rats

The effect of obstructive jaundice on wound healing was investigated in an experimental study of gastric and abdominal wounds in rats after ligation and division of the common bile duct. The healing of a parietal defect in these animals showed histologic evidence of delayed healing compared with controls. The bursting strength of the abdominal incision was also decreased, but not that of the stomach. These findings suggest that the biochemical changes in the wounds of jaundiced animals interfere with wound repair. The possible causes of this delay in healing and its clinical implications require further investigation.     

Effect of sildenafil on wound healing: an experimental study

Purpose  

We aimed to investigate the effect of sildenafil on the healing process of abdominal wall wound in rats.     

Effect of rapamycin on wound healing: an experimental study

The aim of this study was to investigate the effects of rapamycin (RAPA) on the healing of bladder and abdominal wound closures. Fourteen male Sprague Dawley rats were randomized to receive either RAPA (3 mg/d) or placebo. A midline laparotomy was performed. The bladder was cut and closed with 4-0 Vicryl in a double layer. The fascia was closed with 0 nylon suture, and the skin closed with a subcuticular 2-0 nylon suture. The mean RAPA level was 9.1 ng/mg. Eosinophil and neutrophil infiltration, and the presence and degree of myofibroblast proliferation were significantly higher in the bladder, fascia, and dermis of the control group. Lymphocyte infiltration was similar in each group. Mean microvessel density as well as the percentage of cells expressing vascular endothelial growth factor in the bladder, fascia, and dermis were significantly lower among the RAPA group. Both proliferating cell nuclear antigen labeling indices for inflammatory cells in the fascia, dermal fibroblasts, and epithelial cells in the placebo group were significantly higher. No difference was observed for hydroxyproline levels in both the bladder and fascia between the groups. In conclusion, we found that RAPA treatment affected all steps of the wound healing process by decreasing the inflammatory cell number, angiogenesis, and myofibroblast proliferation, so the wound healing process was delayed and consequently the tensile strength of the wound decreased.     

An experimental study on pyogenic osteomyelitis with special reference to polymicrobial infections

The author used the following method to successfully devise a model of experimental osteomyelitis caused by two different bacteria. A 3-mm silk thread (No. 5) soaked in Staphylococcus aureus (1.0 X 10(4) CFU) and Pseudomonas aeruginosa (1.0 X 10(5) CFU) suspensions was dried under reduced pressure. The silk thread was inserted into the metaphysis of the right tibia of mice. Experimental osteomyelitis caused by these two species of bacteria was successfully produced in all the mice, and this infection was similar to osteomyelitis in man. After prior infection with S. aureus, P. aeruginosa (1.0 X 10(3) CFU) was inoculated directly into the tibia of mice during the acute and chronic stages of the S. aureus infection, and secondary infection by P. aeruginosa was confirmed in all the mice. Using this experimental model of osteomyelitis, the author administered an antibiotic that is effective against only S. aureus in mice and observed abrupt growth of P. aeruginosa to elucidate certain aspects of the bacterial replacement phenomena.     

The effect of local infection upon wound healing: an experimental study

Local infection was introduced into rat abdominal wounds using a 10(8) bacterial/ml inoculum. Three groups of infection were used: Staphylococcus aureus, Pseudomonas aeruginosa and a combination group of Escherichia coli and Proteus mirabilis. Infection was shown to delay healing as judged by bursting tests. Fibroblast proliferation was depressed at the wound edges but there was an increase in the total amount of hydroxyproline present. Small vessel angiogenesis was increased in areas of abscess formation but larger vessels were commonly blocked by thrombus or distorted by surrounding inflamed tissue. The possible causes of these effects are discussed.     

Jaundice and wound healing: an experimental study.

Obstructive jaundice was induced in rats by ligation and division of the common bile duct. The healing of a standard gastric incision and a parietal peritoneal defect in these animals showed histological evidence of delayed healing compared with controls. The bursting strength of the abdominal incision was also lowered, but not that of the stomach, probably because of the adhesions which reinforced the gastric incisions. Angiography did, however, reveal delay in angiogenesis in the gastric wounds of jaundiced animals. The possible causes of this delay in healing and its clinical implications require further investigations.     

Uraemic arterial disease. An experimental study with special reference to the effect of parathyroidectomy.

A histophatologic study of uraemic arterial lesions was performed in rats. They were made uraemic by 5/6 kidney resection, and the aorta and peripheral arteries were examined after intervals of up to 36 weeks. The characteristics of the arterial lesions were necrosis of medial smooth muscle cells and, in some cases, calcification of the media. The changes appeared first in the aorta, but after long uraemic periods also in peripheral arteries. The incidence and severity of necrosis and of calcification were assessed separately. Parathyroidectomy largely prevented the development of calcification, and to a lesser degree also smooth muscle cell necrosis. The results suggest that secondary hyperparathyroidism plays an important part in the development of uraemic arterial disease.     

Uraemic myocardial disease. An experimental study, with special reference to the effect of parathyroidectomy

A histopathological study of the myocardium was performed in rats made uraemic by a 5/6 kidney resection. The examinations were performed after intervals up to 36 weeks. Uraemia caused focal myocardial necroses, the incidence and severity of which were related to the length and severity of the uraemic state. In the myocardium of some animals intracellularly located calcifications were found. The calcifications usually appeared only in the necrotic areas. The coronary arteries showed only slight or moderate arteriosclerosis without severe obturation of the lumens and the genesis of the necroses is suggested to be factors other than ischaemia or hypoxia. Since secondary hyperparathyroidism might be one such factor, the effect of prior parathyroidectomy was studied. Parathyroidectomy prevented the development of calcifications but not the development of necrosis. However, the significance of secondary hyperparathyroidism in the development of myocardial necroses cannot be fully evaluated from the present study. The protecting effect of parathyroidectomy was probably counterbalanced by the deleterious effect of further elevated serum phosphate levels in the parathyroidectomized animals.     

Bone cement and wound healing. An experimental study in the rat.

The local effect of methyl methacrylate on wound healing was studied in rats using viscose cellulose sponges. A 7 mm diameter cylindrical section was removed from the sponges, filled with freshly prepared bone cement or left empty in controls. Two sponges were implanted subcutaneously into each rat. The concentrations of DNA, RNA-ribose, nitrogen, hydroxyproline, uronic acids and hexosamines of the sponges were determined 5, 10 and 21 days postoperatively. The concentrations of collagen and glycosaminoglycans were similar in experimental and control samples and only small differences were detected in the amounts of DNA. It was concluded that methyl methacrylate bone cement did not have any practical harmful effects on wound healing.     

Differential depressant and electrophysiologic cardiotoxicity of local anesthetics: an experimental study with special reference to lidocaine and bupivacaine

In 15 pigs lidocaine and bupivacaine were injected into the left anterior descending (LAD) coronary artery to investigate the cardiotoxic effects of these drugs. Anesthesia was maintained by a continuous intravenous pentobarbital infusion and ventilation was controlled. Aortic, pulmonary arterial, right atrial, and left ventricular pressures, a standard 12 lead ECG, cardiac output, and great cardiac venous blood flow were recorded. The local anesthetics were administered at body temperature over approximately 10 sec in a random, crossover fashion at the following equipotent anesthetic doses: bupivacaine, 0.25, 0.5, 1, 2, and 4 mg; lidocaine, 1, 2, 4, 8, and 16 mg. The hemodynamic effects were short-lived, peaking about 5 sec after drug infusion. At the highest dose, both drugs decreased left ventricular dP/dT by 28% (P less than 0.001) and aortic blood pressure by 12% (lidocaine) and 8% (bupivacaine) (P less than 0.001 and P less than 0.01). Heart rate, cardiac output, and coronary venous blood flow did not change. Thus, the cardiodepressant ratio between the two drugs was comparable with their local anesthetic the two drugs was comparable with their local anesthetic potency ratio (bupivacaine/lidocaine, 4:1). Seven animals died in ventricular fibrillation within 1 min after 4 mg bupivacaine dose. All animals given 16 mg lidocaine survived. Ventricular fibrillation was preceded by progressive widening of the QRS complexes recorded over the area perfused by the LAD. The ECG changes after 16 mg lidocaine were of the same magnitude as those recorded after 1 mg bupivacaine. In five of the surviving animals 32 and 64 mg lidocaine were injected intracoronarily after termination of the crossover study.(ABSTRACT TRUNCATED AT 250 WORDS)     

An experimental endoscopic study on intestinal ischemic lesions in dogs with special reference to fluorescence endoscopy

In order to clarify the pathophysiology of intestinal ischemic lesions and to make a useful method for the prediction of fate of the ischemic bowel, we devised an experimental model to produce the disorder. Microbarium of 0.5 micrometer in diameter was injected into a branch of the superior mesenteric artery of adult mongrel dogs. The severity of the ischemic lesions depended on the amount of microbarium injected, and lesions could be classified into three types; transient, stricturing and gangrenous, similar to clinical cases. Endoscopic examination was performed, accompanied with fluorescence endoscopy. Fluorescein could not be observed in all types soon after microbarium injection. In the transient type, fluorescein was observed after only a few days in an evenly distributed pattern. However in the stricturing type, the appearance of fluorescein was delayed, and an irregular pattern was observed in about 1 week. The submucosal blood flow was measured by hydrogen clearance method. The fluorescence endoscopic findings were nearly compatible with changes of submucosal blood flow. Fluorescence endoscopy is easily performed and appears to be highly useful in the differentiation of these three types of ischemia in the early stages.