The effect of topical parasympathomimetics on corneal epithelial healing in rabbits

Corneal wound healing is an important process that involves interaction between the different corneal cell layers, growth factors, and environmental conditions. More powerful therapies for the treatment of delayed epithelial wound healing are still being proposed. The objective of this study is to investigate the effects of the direct-acting parasympathomimetic agents on the healing process of corneal epithelium in rabbits. The corneal epithelial defects, 10 mm in diameter, were created in 32 eyes of 16 island rabbits by combination of chemical debridement using n-heptanol and mechanical scraping. Animals were randomly divided into four groups. Groups 1, 2 and 3 were treatment groups; each group consisted of four rabbits (8 eyes). The animals in these groups were treated with topical 1% acetylcholine (ACh), 2% pilocarpine, and 0.75% carbachol drops respectively. In group 4, four rabbits (8 eyes) were used as control group and left for spontaneous healing. The length and area of the defect were measured at days 3,6,9,12,15,18 and 22 after wounding. Areas of the photographically documented fluorescein-stained defects were measured by planimetry. All eyes in the treatment groups reepithelialized completely. The duration for reepithelialization in Groups 1 and 2 was 12 days, and 18 days for Group 3. In the control group reepithelialization occurred within 22 days. The healing rates of corneal epithelium were statistically significantly faster in all treatment groups as compared with the control group at all times (p=0.0001 to 0.0279). Although the rates of wound healing varied, all of the parasympathomimetics used in the present study were found to facilitate wound healing. Our results indicate that direct-acting cholinergic agents, especially ACh and pilocarpine, may have an important therapeutic role in the treatment of severe corneal epithelial injury.     

Age-dependent stimulation by atrium explants or nerve growth factor of nerve fibre outgrowth from cocultured embryonic rat sympathetic ganglia

Whole sympathetic superior cervical ganglia of 14- and 15-day-old rat embryos were cultured in a collagen gel medium for 24 h with or without explants of heart atrium from the same animals or from newborn rats. The extent of nerve fibre outgrowth was estimated by counting the number of nerve fibres crossing each arc of a sector drawn in the microscope ocular. Only few nerve fibres extended from the ganglia of the 14-day-old embryos cultured in the pure control medium. Addition of exogenous nerve growth factor did not stimulate the poor growth. While the growth of nerve fibres in the presence of atrium explants of newborn rats did not significantly differ from that in cultures without any target tissue, the presence of atrium explants of the same, 14-day-old, embryo resulted in clearly enhanced fibre outgrowth from the ganglia, which was inhibited by antiserum to the nerve growth factor. The ganglia of 15-day-old embryos cultured without target tissue in the control medium produced only sparse fibre outgrowth which was excessively increased by exogenous nerve growth factor. Coculture with atrium explants of 15-day-old embryos or newborn rats produced an increased overall nerve fibre growth, as well as predominance of those fibres growing toward the target tissue. The growth-promoting effect of the atrium of 15-day-old embryos was only partially prevented by antiserum to the nerve growth factor, while that elicited by newborn rat atrium was totally inhibited.(ABSTRACT TRUNCATED AT 250 WORDS)     

Corticosterone does not cause testicular toxicopathology in the rat: relevance to methylxanthines, ACTH and stress.

1. Methylxanthines, ACTH and stress are well known to produce testicular pathology (e.g. seminiferous tubule atrophy). Methylxanthines, ACTH and stress alter hormone secretion, particularly from the pituitary-adrenocortical system. Consequently, it has recently been suggested that there may be a causal relationship between changes in endogenous physiological adrenocortical secretions, particularly corticosterone, and testicular pathology. 2. This study tested the hypothesis that corticosterone mediates the testicular effects of both methylxanthine treatment and stress. Corticosterone was administered daily by subcutaneous injection to groups of 10 male rats at dose levels of 2 or 20 mg kg-1 in propylene glycol (1 ml kg-1) for 1 month (the shortest duration of methylxanthine or ACTH exposure known to produce testicular pathology). The highest dose of corticosterone resulted in plasma concentrations that closely matched values resulting from stress (200-700 ng ml-1) compared with controls (< 25 ng ml-1). 3. The highest dose of corticosterone caused reduced body weight gain, lower thymus, adrenal, seminal vesicle and prostate weights, but did not induce any testicular pathology. 4. That a high, but physiologically relevant, dose of corticosterone did not cause testicular pathology in this experiment excludes this steroid in the direct aetiology of methylxanthine, ACTH and stress-induced testicular pathology. Other steroids secreted from the adrenal, in combination with corticosterone, may be involved.     

Finite element analysis of the effects of thermal obturation in maxillary canine teeth.

OBJECTIVE: The purpose of the present study was to determine the distribution and level of temperature, in a model of a maxillary canine, the surrounding periodontal tissues, and the bones, during a System B heat obturation technique simulation. STUDY DESIGN: The temperature distribution was determined by using a three-dimensional finite element analysis. The tooth was assumed to have undergone an endodontic treatment before the application. Heat applications of 200 degrees C and 100 degrees C were considered. RESULTS: By using the virtual model and the simulation technique, the maximum temperature in the periodontal ligament was found to be 43.5 degrees C. CONCLUSIONS: Within the assumptions and the limitations of the study, it was determined that the simulation of System B technique created no potentially harmful levels of temperature throughout the maxillary canine model.     

Experience with and outlook for the use of cisplatin in the combined therapy of osteogenic sarcoma

The effectiveness of cis-diammine-dichloroplatinum (cisplatinum, platidiam, DDP) alone or as a component of combined treatment was evaluated in 85 patients with osteogenic sarcoma. The said drugs were used as adjuvants following radical surgery (group I-18 cases), in combined treatment of solitary and single lung metastases (group 2-7 cases) and in 60 patients with advanced tumors (group 3). An analysis of long-term results showed response in 30.8% in group 3. In group 2, application of chemotherapy plus surgery was followed by remissions of 2-46+-month duration (mean-13.9 months). In group I, 78.7% are expected to survive metastasis-free more than 12 months. Toxicity was moderate, with nausea and vomiting (87.1%), myelosuppression (52.8%), nephrotoxicity (48.6%) and alopecia (75.7%) being the most common side-effects.     

Two large French pedigrees with non syndromic sensorineural deafness and the mitochondrial DNA T7511C mutation: evidence for a modulatory factor

Hearing impairment is the most frequent sensory defect in children, with a genetic basis in about 50% of cases. Several point mutations and deletions in mitochondrial DNA (mtDNA) have been identified in non-syndromic sensorineural hearing loss (NSSNHL). Beside the frequent A1555G mutation, a number of mutations in tRNAs have been reported recently, but their incidence remains unknown. We identified the T7511C mutation in the tRNASer(UCN) gene in two French families with isolated deafness. Maternal transmission was obvious in both. The 15 patients with hearing impairment exhibited a variable disease phenotype in terms of onset, severity, and progression. T7511C was present in all the patients screened. Homoplasmic and heteroplasmic levels were observed and did not correlate with the severity of the disease. T7511C was also present in 12 hearing offspring of the oldest deaf mothers, confirming the existence of modulatory factors. Our data suggest that this mtDNA mutation should be screened for in all cases of familial NSSNHL compatible with maternal transmission.