Effects of intraocular rifampicin on retinal ganglion cell structure:a stereological and histopathological study

AIM:To determine the histopathological changes of rifampicin applied intravitreally on retinal ganglion cells by means of stereological and histopathological methods.METHODS:For this study twenty-four New Zealand adult rabbits were divided into four groups(n=6 for each group).50μg/0.1mL(group 1),100μg/0.1mL(group 2),150μg/0.1mL(group 3) and 200μg/0.1mL(group 4),rifampicin were injected into the vitreous of the right eyes of animals,their left eyes were used as control(group 5).After the 28thday of application,animals were anesthetised with xylazine(8mg/kg,IM) and then their eyes were enucleated immediately.Patterns were taken away and eyes were prepared for both stereological and electromicroscopic observation.RESULTS:Depending on the high dose of rifampicin,some histopathological changes such as cytoplasmic dilatation and damaged membrane were observed on the electromicroscopic level.Using quantitative examination,which was done at the light microscopic level,it was shown that the number of neurons decreased linearly as rifampicin dose increased when compared with the control group.CONCLUSION:Based on these findings,low-dose rifampicin(50μg/0.1mL) may be useful for treatment of the ocular diseases.

Is obstructive sleep apnea syndrome a risk factor for pulmonary thromboembolism？

Background In many studies, obstructive sleep apnea （OSA） has been shown to be an independent risk factor for cardiovascular disease. Conversely, there are few reports establishing possible relation between OSA and venous thromboembolism （VTE）. In this study, the aim is to evaluate OSA via polysomnography in patients with pulmonary embolism and drawing the attention of clinicians to the presence of obstructive sleep apnea syndrome （OSAS） may be a risk factor for pulmonary embolism. Methods Fifty consecutive patients who were diagnosed with pulmonary embolism （PE） were evaluated prospectively for OSAS. Polysomnographic examination was conducted on 30 volunteer patients. The frequency of OSAS in PE was determined and PE cases were compared to each other after being divided into two groups based on the presence of a major risk factor. Results The study consisted of a total of 30 patients （14 females and 16 males）. In 56.7% of the patients （17/30）, OSAS was determined. The percent of cases with moderate and severe OSAS （apnea hipoapnea index 〉15） was 26.7% （8/30）. Patients who had pulmonary thromboembolism （PTE） without any known major VTE risk （n=20）, were compared to patients with VTE risk factors （n=10）, and significantly higher rates of OSAS were seen （70% and 30% respectively; P=0.045）. The mean age of the group with major PE risk factors was lower than the group without major PE risk factors （52 years old and 66 years old, respectively; P=0.015）, however, weight was greater in the group with major PE risk factors （88 kg and 81 kg, respectively; P=-0.025）. By multivariate Logistic regression analysis, in the group without any visible major risk factors, the only independent risk factor for PE was OSAS （P=0.049）. Conclusions In patients with PTE, OSA rates were much higher than in the general population. Moreover, the rate for patients with clinically significant moderate and severe OSA was quite high. PTE patients with OSA symptoms （not syndromes） and without known major risk factor should be examined for OSA. There seems to be a relationship between OSA and PTE. However, whether this relationship is a causal relationship or a relationship due to common risk factors or long-term complications of OSA is not clear. Further comprehensive studies on those special topics are needed to clarify these points.