The morphology, number, and distribution of a large population of confirmed displaced amacrine cells in the adult cat retina

The presence of a large population of some 730,000 displaced amacrines is confirmed in the ganglion cell layer of the cat retina. These cells correspond to the microneurons of Hughes and Wieniawa-Narkiewicz (Nature 284:468-470, '80) and the bar-cells of Hughes (J. Comp. Neurol. 197:303-339, '81): a population of profiles of which the majority had previously been presumed to be glia (Stone: J. Comp. Neurol. 12:337-352, '65; J. Comp. Neurol 180:753-772, '78; Hughes: J. Comp. Neurol. 163: 107-128, '75). A sample of such nonganglion cells was identified by Nissl criteria in an area of retina subsequently subjected to serial sectioning and electron microscopy. Such cells form synapses with other processes in the inner plexiform layer. Members of each morphological subclass were found to bear synapses. In some instances, synapses occurred both onto and from the soma and processes of a cell, which is strong evidence for their being displaced amacrines, or preferably, "amacrines of the ganglion cell layer." In confirmation of their amacrine nature, it was established that the microneurons and bar-cells survive optic nerve section for up to 2.5 years. Ganglion cells underwent retrograde degeneration and completely disappeared in a much shorter time. Injection of kainic acid, a neurotoxin, into an eye whose optic nerve had been cut over 2 years previously resulted in the pyknosis of all morphologically classified microneurons and bar-cells without influence on conventional glial cells. These results further support the conclusion that microneurons and bar-cells are neurons and that they collectively form the displaced amacrine population of the cat ganglion cell layer. The topographic distribution of the displaced amacrines resembles that of the ganglion cells in form; their density peaks at 4,500-5,000 cells mm-2 in the area centralis and falls to less than 1,000 mm-2 in peripheral retina. A ganglion cell distribution map based on the latest morphological criteria derived from this study confirms that there are 170,000 ganglion cells in the cat retina. Displaced amacrines form some 80% of the total neuron population of the cat ganglion cell layer. The large population magnitude of these confirmed displaced amacrines implies their nonectopic origin and now provides a fresh insight into the ontogeny of the cat retinal ganglion cell layer.     

Translation and psychometric validation of the traditional Chinese version of patient-reported outcomes measurement information system Pediatric-25 Profile version 2.0 (PROMIS-25) in Chinese Children with Cancer in Hong Kong

Quality of Life Research - To translate and cross-cultural validate the PROMIS Pediatric-25 Profile 2.0 (PROMIS-25) into traditional Chinese, and to investigate its psychometric properties in...     

松果体区病灶直线加速器放射外科的剂量分布探讨

通过运用仿真人体模型对松果体区靶病灶直线加速器多聚弧照射的监测，论证直线加速器作为放射外科工具治疗颅内病变的科学性，探讨有关辐射参数对剂量分布的影响。作者认为，直线器放射外科可实现与伽玛马相似的剂量分布，同是神经外科安全有效的治疗技术，准直器孔径越小，照射范围越大，则剂量梯度即越大，剂量分布越理想；靶区最大剂量对上器孔径有相当高的依赖性，本文还就合理的照射弧范围及边缘处方剂量作了讨论。     

Morphine-induced metabolic changes in human brain. Studies with positron emission tomography and [fluorine 18]fluorodeoxyglucose

Morphine sulfate effects (30 mg, intramuscularly) on cerebral glucose utilization and subjective self-reports were examined in 12 polydrug abusers by positron emission tomography and [fluorine 18]fluorodeoxyglucose in a double-blind placebo-controlled crossover study. During testing, subjects sat with eyes covered, listening to white noise and "beep" prompts. Morphine significantly reduced glucose utilization by 10% in whole brain and by about 5% to 15% in telencephalic areas and the cerebellar cortex, assuming no contribution of hypercapnia. When the contribution of PaCO2 (45 minutes after morphine was administered) was partialled out, significant morphine-induced reductions persisted in whole brain and six cortical areas. Irrespective of morphine, left-greater-than-right asymmetry occurred in the temporal cortex, and an interaction between hemisphere and drug was noted in the postcentral gyrus. In most cases, effects on glucose utilization were not significantly related to measures of euphoria.     

Cigarette smoking enhances the elimination of quinine

The pharmacokinetics of a single dose (600 mg) of quinine sulphate were examined in a group of non-smokers (n = 10) and in heavy cigarette smokers (n = 10). The mean (+/- s.d.) oral clearance of quinine in smokers (0.189 +/- 0.075 1 h(-1) kg(-1)) was significantly greater than in non-smokers (0.107 +/- 0.045 1 h(-1) kg(-1) , P < 0.01). The unbound clearance of quinine which reflects activity of the drug-metabolizing enzyme, was considerably greater (1.5-fold) in the smokers than in the non-smoker subjects. The mean elimination half-life of quinine in smokers was 7.5 +/- 1.4 (s.d.) h, significantly shorter (P < 0.005) than the mean value in non-smokers (12.0 +/- 3.1 h). These results suggest that cigarette smoking enhances the elimination of quinine. The clinical significance of these findings is unknown but they indicate the need for caution in the administration of quinine to patients who are heavy cigarette smokers.     

An approach to preventing methotrexate prescribing errors in rheumatoid arthritis

Methotrexate is an effective treatment for rheumatoid arthritis and is fairly well tolerated by patients when used appropriately. However, errors do occur due to a lack of awareness of the normal dosage range and potentially serious dose related side effects of methotrexate among physicians, pharmacists, and nurses. The approach taken by one hospital to prevent methotrexate prescribing errors includes daily monitoring of methotrexate by a pharmacist, building caution flags in the order loading program of the pharmacy computer system, and educating healthcare professionals to heighten awareness when prescribing, dispensing, and administering methotrexate for rheumatoid arthritis. At the hospital, since the institution of these policies and education of pharmacists, nurses, and physicians, there have been no incidents of methotrexate prescribing errors.