Sol Particle Immunoassay (SPIA)

We describe the use of inorganic (metal) colloidal particles as a label for immunoassays. Dose-response curves for human placental lactogen (HPL) and human chorionic gonadotrophin (HCG) were obtained with sandwich immunoassays, using conjugates consisting of antibody-coated colloidal gold or silver particles. Several techniques were used to measure the amount of bound conjugate, viz. colorimetry and carbon rod atomic absorption spectrophotometry (CRAAS). At higher antigen concentrations the results of the assay could be read by the naked eye.

Using gold particles as label and CRAAS as detection method, we found a detection limit for a sandwich HPL sol particle immunoassay (SPIA) of 1,4 pmol/l, which was equal to that of an optimalized competitive radioimmunoassay. When using a colorimeter the detection limit for HPL of this SPIA was 5,4 pmol/l, which was superior to that of a corresponding sandwich enzyme-immunoassay (EIA). HPL and HCG were also simultaneously determined, using micro-titration plates, coated with a mixture of anti-HPL and anti-HCG, and a mixture of silver particle anti-HPL conjugate and gold particle anti-HCG conjugate. CRAAS was used to measure the bound amount of silver and gold conjugate. This simultaneous assay requires more work in order to obtain better sensitivities.     

肝细胞生长因子诱导实验性视网膜脱离的病理机制研究

目的 观察肝细胞生长因子（HGF）对视网膜色素上皮（RPE）细胞屏障功能的影响以及RPE内过度表达HGF导致视网膜脱离（RD）的病理机制。 方法 编码HGF（AdCMV.HGF）、绿色荧光蛋白（Ad CMV.GFP）的E1/E3缺失的腺病毒载体，以5×10⁴ 噬斑形成单位（pfu）/眼注射到成年有色兔的视网膜下。检查注射后3、7、14、28 d时的眼底及组织病理变化,利用免疫组织化学和酶联免疫吸附试验（ELISA）方法检测HGF在视网膜和玻璃体的表达水平。 结果 对照组注射Ad CMV.GFP眼显示GFP几乎仅表达于PRE单核细胞层，AdCMV.HGF注射眼在注射点处的PRE细胞出现强的HGF免疫阳性反应。玻璃体内HGF的表达水平在注射7 d后达到最高峰、28 d后降低到基础水平。在HGF的表达期内AdCMV.HGF注射眼出现慢性RD和脉络膜慢性炎症。在RD区域，视网膜下的空间内可见增生性的RPE细胞，部分实验兔眼还产生多层的细胞膜结构。 结论 RPE内过度表达的HGF能引发慢性浆液性RD，同时伴有视网膜下RPE增生。提示HGF可能作为治疗RD的作用靶点。(中华眼底病杂志，2007，23：193-197)     

Results of specific hyposensitization in children with pollinosis

Hyposensitization was carried out in 120 children aged 5 to 15 years with proven sensitivity to various pollen for 3 to 5 years before the start of the season. By reason of the results of intracutaneous tests 90 patients were treated with mixed pollen allergen and 30 patients with grass pollen allergen. A retrospective study was undertaken on the base of a questionnaire. Every year after the season duration and severity of symptoms as well as consumption of medicine were registered. The total success of hyposensitization amounted to 70.8% and this result varied on the one hand in dependence of the duration of disease on the other hand in dependence of the duration of treatment. A more inconvenient result was seen in those children who suffered from asthmatic symptoms exclusively compared to patients with hay fever. Local side effects resulted sporadically in 71.5% and systemic side effects in 15.7% by subcutaneous injection of depot-pollen allergen. Despite of extensive and not indifferent mode of treatment, hyposensitization should be performed in a correct way as soon as possible after exact indication.     

UV light-induced autofluorescence of full-length Abeta-protein deposits in the human brain

The formation of amyloid plaques is a hallmark of Alzheimer's disease (AD). Amyloid plaques and vascular amyloid deposits in cerebral amyloid angiopathy (CAA) consist of the beta-amyloid protein (Abeta) in association with other proteins. These Abeta-deposits can be visualized by thioflavin S, Congo red staining, silver staining methods and immunohistochemistry. Senile plaques also have been shown to exhibit blue autofluorescence. Here we report that UV light-induced autofluorescence is restricted to full-length Abeta-containing amyloid plaques and is also seen in blood vessels affected by CAA. Different types of samples from AD and control cortices were examined: native samples, formalin-fixed paraffin and polyethylene glycol-embedded tissue sections. These samples were viewed with a fluorescence microscope under UV light excitation (360 - 370 nm). By emitting blue fluorescence (>420 nm), amyloid plaques and blood vessels affected by CAA were detected in AD and CAA samples. Combination with immunofluorescence against anti-Abeta1-42, anti-Abeta17-24, and anti-Abeta8-17 demonstrated co-localization of the autofluorescent deposits with full-length Abeta containing Abeta-deposits. N-terminal truncated Abeta-deposits, such as the fleecy amyloid, do not exhibit autofluorescence. In doing so, Abeta-autofluorescence is a suitable method for screening native tissue samples for full-length Abeta-deposits. In contradistinction to conventional and immunohistochemical procedures, detection of plaques and CAA by autofluorescence enables the recognition of full-length Abeta-deposits in the human brain without any chemical interaction whatsoever on the part of Abeta.     

Estimating the prevalence of agitation in community-dwelling persons with Alzheimer's disease

To estimate the prevalence of, and develop norms for, significant agitation in community-dwelling persons with Alzheimer's disease (AD), the authors applied three different criteria to persons with AD (n=235) and normal elderly control subjects (NEC; n=64). The criteria were used to identify the minimum total score on the Cohen-Mansfield Agitation Inventory (CMAI) that represents significant or "excessive" agitation and to estimate its prevalence. The "ultraliberal" criterion resulted in 99.1% of persons with AD and 56.6% of NEC being classified as "excessively" disturbed. The "liberal" and "conservative" criteria classified 66.7% and 68.2% of persons with AD, and no NEC, as "excessively" disturbed. The authors conclude that the best estimate of prevalence of excessive agitation in this population is 67.5%, and that individuals with CMAI scores of 0 to 14 probably should not be considered to have excessive agitation.     

Brain MRI hippocampal volume and prediction of clinical status in a mild cognitive impairment trial

Mild Cognitive Impairment (MCI) is considered a transitional stage in the pathogenesis of Alzheimer’s disease; however, not all MCI patients progress to clinically defined AD or decline at identical rates. Hippocampal atrophy, as measured by Magnetic Resonance Imaging (MRI), may be a marker for hippocampal pathology in patients with MCI and predict a more rapid deterioration to clinical AD. In this study, we used MRI data from an ongoing MCI clinical trial to determine whether MRI hippocampal volume at baseline was associated with cognitive and functional performance in MCI subjects and whether it predicted those individuals who were more likely to develop AD. We performed correlational analyses between the MRI hippocampal volumes at study entry and the subjects’ concurrent performance on neuropsychological measures and clinical ratings. Larger hippocampal volume was associated with better performance on tests of memory, general cognition, and overall clinical ratings. Further analyses suggested that a smaller baseline hippocampal volume may be associated with a higher risk of developing clinical AD. As the trial is still ongoing, these results require confirmation once the trial is completed. In summary, these data suggest that MRI hippocampal volume may be a useful correlate of disease severity in MCI subjects and a prognostic indicator of subsequent AD.     

Age at onset is associated with disease severity in Lewy body variant and Alzheimer's disease

This study investigated the influence of age at onset on cognitive performance, neuropathological and neurochemical features in autopsy-confirmed sporadic Lewy body variant (LBV) and in Alzheimer's disease (AD). We compared 28 early-onset (< or = 70 years) LBV subjects with 28 matched late-onset (> 70 years) subjects. Similarly, we examined the same features in 89 early onset AD and 89 matched late onset AD patients. Patients with early onset LBV and early onset AD declined more rapidly, had more neuritic plaques, and greater neocortical cholinergic loss compared to late onset LBV and late onset AD subjects. Taken together, these results suggest that for both LBV and AD, earlier age at onset may predict a more aggressive disease course.     

Mnemonic deficits in animals depend upon the degree of cholinergic deficit and task complexity

The role of cholinergic basal forebrain (CBF) neurons in mnemonic behaviors was investigated using the immunotoxin 192IgG-saporin. We assessed two routes of immunotoxin administration: intracerebroventricular (ICV) and intraparenchymal (INTRA). INTRA lesions of the medial septum (MS) and/or the nucleus basalis magnocellularis (NBM) were compared with ICV-lesions, INTRA-phosphate-buffered saline injected, and naive controls. The INTRA-NBM/MS and ICV NBM/MS lesions produced a similar depletion of choline acetyltransferase activity of 80% across all CBF projections. Water maze performance was similarly impaired for ICV- and INTRA-NBM/MS animals during various phases of testing, whereas animals with individual lesions of the NBM or MS performed at the level of controls. In contrast to the allocentric demands of water maze performance, the egocentric-based T-maze task revealed a vast group difference between the ICV- and the INTRA-NBM/MS animals. INTRA-NBM/MS animals showed a severe deficit in the non-match- and match-to-position version, whereas again, animals with single lesions were unimpaired. In addition, a dichotomy between animals with complete cholinergic deafferentation was observed in the inhibitory avoidance task. ICV-NBM/MS showed a diminished retention for the aversive stimulus while the INTRA-NBM/MS animals remembered well. During plus maze testing, only the INTRA-NBM/MS animals had a reduced level of anxiety. Although non-CBF regions may have been differently affected by the two routes of immunotoxin administration, global measures of arousal, motivation, and motor initiation did not reveal a different behavioral pattern. Our findings suggest that a dynamic interplay exists between the degree of cholinergic deficit and task demands revealing different types of mnemonic impairments.     

Assessing Alzheimer's disease patients with the Cohen-Mansfield Agitation Inventory: scoring and clinical implications.

We explored the applicability of the standard scoring of the Cohen-Mansfield Agitation Inventory (CMAI), a widely used nursing-home derived instrument, to community-dwelling persons with Alzheimer's disease (AD). Item responses to the CMAI were gathered from participants in two large clinical studies, one of which specifically included patients with behavioral disturbances. Confirmatory factor analysis in these two groups of well-characterized AD patients suggested that conventional CMAI subscoring did not adequately describe the responses of these two groups. Exploratory factor analysis indicated that the four CMAI subscores, based on a verbal-physical and aggressive-non-aggressive conceptualization of behavioral disturbance, did not fit community dwelling persons with AD. Based on cross-sectional and longitudinal analyses, there was suggestive evidence for three behavioral clusters, but these clusters did not achieve statistical significance Overall, the CMAI seemed best suited to describe the overall level rather than the specific subtypes of behavioral dyscontrol in community-dwelling persons with AD.