The stabilization of ferrous iron by a toxic β-amyloid fragment and by an aluminum salt

Aluminum is a recognized neurotoxin in dialysis encephalopathy and may also be implicated in the etiology of neurodegenerative disease, particularly Alzheimer's disease. Alzheimer's disease is suspected to be associated with oxidative stress, possibly due to the pro-oxidant properties of β-amyloid present in the senile plaques. The underlying mechanism by which this occurs is not well understood although interactions between amyloid and iron have been proposed. The presence of low molecular weight iron compounds can stimulate free radical production in the brain. This study provides a possible explanation whereby both aluminum and β-amyloid can potentiate free radical formation by stabilizing iron in its more damaging ferrous (Fe²⁺) form which can promote the Fenton reaction. The velocity, at which Fe²⁺ is spontaneously oxidized to Fe³⁺ at 37°C in 20 mM Bis–Tris buffer at pH 5.8, was significantly slowed in the presence of aluminum salts. A parallel effect of prolongation of stability of soluble ferrous ion, was found in the presence of β-amyloid fragment (25–35). Ascorbic acid, known to potentiate the pro-oxidant properties of iron, was also capable of markedly stabilizing ferrous ions.     

Respiratory viruses in adult liver transplant recipients.

BACKGROUND: The contribution of respiratory viruses to respiratory disease in adult liver transplant (LT) recipients has not been studied. We performed a prospective audit to document the incidence of respiratory syncytial viruses ([RSVs], parainfluenza virus, influenza virus, and adenovirus) after LT, and to determine their contribution to respiratory disease in this setting. METHODS: Consecutive adult recipients were followed for 8 months after LT. Throat swabs were collected weekly for up to 12 weeks after LT, and virological surveillance was performed using conventional techniques (direct immunofluorescence and cell culture). A polymerase chain reaction assay for RSV was subsequently performed on selected specimens. Clinical data, including episodes of respiratory disease, were also recorded. RESULTS: During the study period, 51 patients received 53 LT. Five patients died, but no viruses were isolated from these patients at any stage. A total of 323 swabs were examined by conventional techniques and yielded 35 viral isolates (10.8%). Herpes simplex virus (type 1) accounted for 33 isolates, none of which were associated with respiratory disease. Two of 323 swabs (0.62%), in 2 patients, yielded respiratory viruses (both RSV); both patients had self-limiting, mild, upper respiratory tract symptoms. In these 2 patients, the polymerase chain reaction assay was more sensitive than conventional techniques and was able to detect extended RSV excretion. Of 51 recipients, 31 (61%) were always negative for viruses. Of 51 recipients, 10 developed respiratory failure, but no respiratory viruses were isolated from any of these patients. CONCLUSIONS: Respiratory viruses are rarely isolated from adult recipients after LT and are not associated with serious morbidity or with mortality. Routine surveillance for respiratory viruses in this patient population is not justified on the basis of this study.     

Collapsin-1/semaphorin-III/D is regulated developmentally in Purkinje cells and collapses pontocerebellar mossy fiber neuronal growth cones

Most axons in the CNS innervate specific subregions or layers of their target regions and form contacts with specific types of target neurons, but the molecular basis of this process is not well understood. To determine whether collapsin-1/semaphorin-III/D, a molecule known to repel specific axons, might guide afferent axons within their cerebellar targets, we characterized its expression by in situ hybridization and observed its effects on mossy and climbing fiber extension and growth cone size in vitro. In newborn mice sema-D is expressed by cerebellar Purkinje cells in parasagittal bands located medially and in some cells of the cerebellar nuclei. Later, sema-D expression in Purkinje cells broadens such that banded expression is no longer prominent, and expression is detected in progressively more lateral regions. By postnatal day 16, expression is observed throughout the cerebellar mediolateral axis. Collapsin-1 protein, the chick ortholog of sema-D, did not inhibit the extension of neurites from explants of inferior olivary nuclei, the source of climbing fibers that innervate Purkinje cells. In contrast, when it was applied to axons extending from basilar pontine explants, a source of mossy fiber afferents of granule cells, collapsin-1 caused most pontine growth cones to collapse, as evidenced by a reduction in growth cone size of up to 59%. Moreover, 63% of pontine growth cones arrested their extension or retracted. Its effects on mossy fiber extension and its distribution suggest that sema-D prevents mossy fibers from innervating inappropriate cerebellar target regions and cell types.     

Childhood Asthma in Low-Income Hispanic and Non-Hispanic White Families in a Rural State: The Impact-on-Family Scale

We measured the impact on family functioning reported by low-income Hispanic and non-Hispanic White parents of children (N = 415, mean age 8.7 years) with asthma living in a rural state. A number of factors were associated with impact, using the Impact-on-Family Scale (Stein & Jessop, 1985). In order of importance, the factors were number of school days missed, nighttime symptoms, number of as-needed medications, and Spanish version of the tool. These factors accounted for approximately 13 % of the variance in total impact score. There were no differences in impact score between urban and rural parents or by ethnicity. The findings indicate that perceived parental impact is not strongly associated with commonly measured demographic and morbidity measures. The relation of these data to the recommendations of the National Asthma Guidelines (National Heart, Lung, and Blood Institute, 1997) is discussed.     

New Principle of Closed System Centrifugation

Guest Editor's Introduction: Much of the early work on continuous flow centrifugation for the separation of blood components was done in the early 1950s in the laboratory of Dr. Cohn. The performance of these instruments and the effects on blood components were studied by teams of investigation under the directions of Tullis and Surgenor. This paper describes the basic components and the instruments developed by these efforts. The instrument was, then, manufactured by Arthur D. Little, Inc. and became known as the Cohn ADL Centrifuge. This paper was printed in Science vol. 124, page 792–797 (1956) and reprinted here with permission.     

针刺不同穴位对视网膜电图和皮层视觉诱发电位的影响

目的:观察针刺不同穴位对健康成人视网膜电图(ERG)和视觉诱发电位(VEP)的影响,探讨经穴功能的相对特异性。方法:33名志愿者参与本实验。以直径为1 cm装有导电膏的圆盘形表面电极放置于眼眶下缘皮肤表面(测ERG),或放置于正中线右旁开5 cm、耳上5 cm的枕部皮肤表面(测VEP)。视觉刺激的闪光频率为1次/s,光源与眼距离50 cm。受试者静卧,给予20次闪光刺激,同时用叠加仪将20次ERG、VEP反应进行平均加算,获得1次叠加结果。按同法记录3～5次反应作为针前基础值。然后刺激穴位,待出现针感时连接电子刺激器,给予电脉冲刺激,频率0.5 Hz,波宽0.2 ms,电针10 min后记录3～5次ERG、VEP作为针时值。测试穴位分别为光明、内关、足三里,每穴测试时间至少相隔3 d。结果:电针刺激光明穴对ERGb波振幅、VEP P100振幅的影响较大,变化是双向的,而电针刺激内关穴和足三里穴对ERGb波的振幅和VEP P100振幅的影响比较小,其差异十分显著(P0.01)。结论:电针胆经光明穴对ERG和VEP振幅的影响明显大于电针内关和足三里,提示不同穴位对ERG、VEP活动的影响具有相对的特异性。     

浅谈中西医结合治疗癌性疼痛

癌性疼痛是肿瘤最为常见的临床症状之一,如何有效地控制癌性疼痛,改善癌症病人的生活质量,延长生存期已成为全球关注的焦点。WHO调查认为:进展期癌症和终末期癌症病人约75%～90%以疼痛为主要临床症状,经过治疗90%的癌性疼痛可缓解。单纯运用西医的三阶梯镇痛疗法会导致病人药物成瘾性及较大的毒副作用;而单纯运用中医药疗法止痛效果不甚显著。因此,将中西医疗法结合运用到治疗癌性疼痛上,将成为今后癌症病人综合治疗的重要环节,尤其近年来中医学以其独特的理论体系,辨病辨证相结合,采用中药内服、外用、针灸等方法,对癌性疼痛的治疗研究取得了满意的进展。