I know your face but can't remember your name: Age-related differences in the FNAME-12NL.

OBJECTIVE: The Face-Name Associative Memory test (FNAME) has recently received attention as a test for early diagnosis of Alzheimer's disease. So far, however, there has been no systematic investigation of the effects of aging. Here, we aimed to assess the extent to which the FNAME performance is modulated by normal ageing. METHOD: In a first step, we adapted the FNAME material to the Dutch population. In a second step, younger (n = 29) and older adults (n = 29) were compared on recall and recognition performance. RESULTS: Significant age effects on name recall were observed after the first exposure of new face-name pairs: younger adults remembered eight, whereas older adults remembered a mean of four out of twelve names. Although both age groups increased the number of recalled names with repeated face-name exposure, older adults did not catch up with the performance of the younger adults, and the age-effects remained stable. Despite of that, both age groups maintained their performance after a 30-min delay. Considering recognition, no age differences were demonstrated, and both age groups succeeded in the recognition of previously shown faces and names when presented along with distractors. CONCLUSIONS: This study presents for the first time the results of different age groups regarding cross-modal associative memory performance on the FNAME. The recall age effects support the hypothesis of age-related differences in associative memory. To use the FNAME as an early cognitive biomarker, further subscales are suggested to increase sensitivity and specificity in the clinical context.

Physical and biological performance of a novel block copolymer nerve guide.

Although the ability to regenerate is evident in the nervous system, lesioned neurites are unable to cross gaps in neuronal pathways. In order to bridge gaps, guiding cues are essential to direct neurite regrowth. To overcome many of the shortcomings of polymer-based nerve guides, we developed a bioresorbable nerve guide composed of a novel trimethylene carbonate-caprolacton block copolymer (TMC-CL). Pore formation was controlled by using special solvent/precipitation media compositions in combination with the pore forming agent poly ethylene glycol (PEG). NMR spectroscopy, shear force-, compression-, and permeation assays were used for conduit characterization. The polymer conduit has a semipermeable wall with submicron pores to allow free metabolite/drug exchange. In order to investigate the principle of temporally controlled expression of therapeutic proteins in nerve guides, Neuro-2a cells were genetically engineered to express the reporter gene product green fluorescent protein (GFP) under the control of the Tet-On system. When these transduced cells were encapsulated in nerve guides, GFP expression could be induced for days by adding the antibiotic tetracycline derivative doxycycline to the nerve guide environment. Furthermore, encapsulated dorsal root ganglia (DRG) produced long neurites in vitro. In subsequent in vivo experiments, nerve guides filled with Schwann cells (SC) were implanted into lesioned spinal cords of adult rats. Regeneration of spinal cord axons into nerve guides was promoted by co-implanted Schwann cells. The data suggest that the novel TMC-CL nerve guides provide a promising tool for neuroregeneration.

Curative resection is the single most important factor determining outcome in patients with pancreatic adenocarcinoma.

BACKGROUND: Mortality rates associated with pancreatic resection for cancer have steadily decreased with time, but improvements in long-term survival are less clear. This prospective study evaluated risk factors for survival after resection for pancreatic adenocarcinoma. METHODS: Data from 366 consecutive patients recorded prospectively between November 1993 and September 2001 were analysed using univariate and multivariate models. RESULTS: Fifty-eight patients (15.8 per cent) underwent surgical exploration only, 97 patients (26.5 per cent) underwent palliative bypass surgery and 211 patients (57.7 per cent) resection for pancreatic adenocarcinoma. Stage I disease was present in 9.0 per cent, stage II in 18.0 per cent, stage III in 68.7 per cent and stage IV in 4.3 per cent of patients who underwent resection. Resection was curative (R0) in 75.8 per cent of patients. Procedures included pylorus-preserving Whipple resection (41.2 per cent), classical Whipple resection (37.0 per cent), left pancreatic resection (13.7 per cent) and total pancreatectomy (8.1 per cent). The in-hospital mortality and cumulative morbidity rates were 2.8 and 44.1 per cent respectively. The overall actuarial 5-year survival rate was 19.8 per cent after resection. Survival was better after curative resection (R0) (24.2 per cent) and in lymph-node negative patients (31.6 per cent). A Cox proportional hazards survival analysis indicated that curative resection was the most powerful independent predictor of long-term survival. CONCLUSION: Resection for pancreatic adenocarcinoma can be performed safely. The overall survival rate is determined by the radicality of resection. Patients deemed fit for surgery who have no radiological signs of distant metastasis should undergo surgical exploration. Resection should follow if there is a reasonable likelihood that an R0 resection can be obtained.

Biological activity of RE-1 silencing transcription factor (REST) towards distinct transcriptional activators.

The zinc finger protein RE-1 silencing transcription factor (REST) is a transcriptional repressor that represses neuronal genes in non-neuronal tissues. We have analyzed the ability of REST and the REST mutants, RESTDeltaN and RESTDeltaC lacking either the N-terminal or C-terminal repression domains of REST, to inhibit transcription mediated by distinct transcriptional activator proteins. For this purpose we have designed an activator specific assay where transcription is activated as a result of only one distinct activation domain. In addition, binding sites for REST were inserted in the 5'-untranslated region or at a distant position downstream of the polyadenylation signal. The results show that REST or the REST mutants containing only one repression domain were able to block transcriptional activation mediated by the transcriptional activation domains derived from p53, AP2, Egr-1, and GAL4. Moreover, REST, as well as the REST mutants, blocked the activity of the phosphorylation-dependent activation domain of Elk1. However, the activity of the activation domain derived from cAMP response element binding protein 2 (CREB2), was not inhibited by REST, RESTDeltaN or RESTDeltaC, suggesting that REST is able to distinguish between distinct transcriptional activation domains. Additionally, the activator specific assay, together with a positive-dominant mutant of REST that activated instead of repressed transcription, was used in titration experiments to show that REST has transcriptional repression and no transcriptional activation properties when bound to the 5'-untranslated region of a gene.

Biological activity of mammalian transcriptional repressors.

Research on the regulation of transcription in mammals has focused in recent years mainly on the mechanism of transcriptional activation. However, transcriptional repression mediated by repressor proteins is a common regulatory mechanism in mammals and might play an important role in many biological processes. To understand the molecular mechanism of transcriptional repression, the activity of eight mammalian repressors or repressor domains was investigated using a set of model promoters in combination with two different transcriptional detection methods. The repressors studied were: REST, the thyroid hormone receptors alpha and beta, the zinc finger protein NK10 containing a 'krüppel-associated box' (KRAB), repressor domains derived from the proteins Egr-1, Oct2A and Dr1 and the repressor/activator protein YY1. Here we show that the repressor domains of REST, Egr-1, the thyroid hormone receptors alpha< and beta and NK10 were transferable to a heterologous DNA-binding domain and repressed transcription from proximal and distal positions. Moreover, these repressor domains also blocked the activity of a strong viral enhancer in a 'remote position'. Thus, these domains are 'general' transcriptional repressor domains. The 'krüppel-associated box' was the most powerful repressor domain tested. In contrast, the repressor domains derived from Oct2A and Dr1 were inactive when fused to a heterologous DNA-binding domain. The repressor domain of YY1 exhibited transcriptional repression activity only in one of the transcriptional assay systems. The recruitment of histone deacetylases to the proximity of the basal transcriptional apparatus was recently discussed as a mechanism for some mammalian transcriptional repressor proteins. Here we show here that histone deacetylase 2, targeted to the reporter gene via DNA-protein interaction, functions as a transcriptional repressor protein regardless of the location of its binding site within the transcription unit.

The human transcriptional repressor protein NAB1: expression and biological activity.

The zinc finger protein early growth response 1 (Egr-1) is a transcriptional activator involved in the regulation of growth and differentiation. Egr-1 has a large activating domain and three zinc finger motifs that function as a DNA binding region. We show here that a third functional domain of the Egr-1 protein, localized between the extended activation domain and the zinc finger DNA binding region, acts as a transcriptional repressor domain when fused to a heterologous DNA binding domain (DBD). Through protein-protein interaction this inhibitory domain of Egr-1 brings the transcriptional corepressor NAB1 in close proximity to the transcription unit. NAB1 is expressed ubiquitously in human cell lines as shown by RNase protection mapping. Overexpression studies revealed that NAB1 is able to completely block transcription mediated by Egr-1. In addition, the transcriptional repression activity of a fusion protein containing the inhibitory domain of Egr-1 and the DBD of the yeast transcription factor GAL4 was increased by overexpression of NAB1. A fusion protein consisting of the DBD of GAL4 and the coding region of human NAB1 repressed transcription from model promoters with engineered upstream GAL4 binding sites. The GAL4-NAB1 fusion protein functioned from proximal and distal positions indicating that NAB1 displays transcriptional repressor activity at any position within the transcription unit. Thus, the biological function of the inhibitory domain of Egr-1 is solely to provide a docking site for NAB1 via protein-protein interaction.

Regulation of neuronal gene expression.

Humans as multicellular organisms contain a variety of different cell types where each cell population must fulfill a distinct function in the interest of the whole organism. The molecular basis for the variations in morphology, biochemistry, molecular biology, and function of the various cell types is the cell-type specific expression of genes. These genes encode proteins necessary for executing the specialized functions of each cell type within an organism. We describe here a regulatory mechanism for the expression of neuronal genes. The zinc finger protein REST binds to the regulatory region of many neuronal genes and represses neuronal gene expression in nonneuronal tissues. A negative regulatory mechanism, involving a transcriptional repressor, seems to play an important role in establishing the neuronal phenotype.

Inverse expression pattern of REST and synapsin I in human neuroblastoma cells.

The zinc finger protein REST is a repressor of neuronal genes in nonneuronal tissues. We have analyzed the expression of REST, together with the expression of a REST target gene, encoding synapsin I, in human neuroblastoma cells. It was found that REST and synapsin I are coexpressed in neuroblastoma cell lines, although the expression of REST was inversely proportional to the levels of synapsin I mRNA. Thus, increased expression of synapsin I was directly correlated with decreased expression of REST. These expression data are in excellent correlation with synapsin I promoter activity measured in neuroblastoma cells showing that an increase in the REST concentration switched off synapsin I promoter activity. We conclude that the concentration of REST determines the expression level of neuronal genes such as the synapsin I gene.

Biological activity and modular structure of RE-1-silencing transcription factor (REST), a repressor of neuronal genes.

The zinc finger protein RE-1-silencing transcription factor (REST)1 is a transcriptional repressor that represses neuronal genes in nonneuronal tissues. Transfection experiments of neuroblastoma cells using a REST expression vector revealed that synapsin I promoter activity is controlled by REST. The biological activity of REST was further investigated using a battery of model promoters containing strong promoters/enhancers and REST binding sites. REST functioned as a transcriptional repressor when REST binding motifs derived from the genes encoding synapsin I, SCG10, alpha1-glycine receptor, the beta2-subunit of the neuronal nicotinic acetylcholine receptor, and the m4-subunit of the muscarinic acetylcholine receptor were present in the promoter region. No differences in the biological activity of these REST binding motifs tested were detected. Moreover, we found that REST functioned very effectively as a transcriptional repressor at a distance. Thus, REST represents a general transcriptional repressor that blocks transcription regardless of the location or orientation of its binding site relative to the enhancer and promoter. This biological activity could also be attributed to isolated domains of REST. Both repressor domains identified at the N and C termini of REST were transferable to a heterologous DNA binding domain and functioned from proximal and distal positions, similar to the REST protein.

Enzyme sensor-FIA-system for on-line monitoring of glucose, lactate and glutamine in animal cell cultures.

Enzyme sensors for glucose, lactate and glutamine were connected via flow-injection analysis (FIA) devices to two different bioprocesses. They were used for on-line process control of perfused bioreactor systems containing mammalian cell lines producing a monoclonal antibody and recombinant interleukin-2. The biosensor system gives direct access to important process data which can be used as control parameters for long term cell cultivation systems.

Elimination of disturbing birefringence effects on faraday rotation.

The resolution of a practical Faraday effect device is limited by birefringence. The case where both Faraday effect and birefringence are small is treated. Aleans for obtaining a high degree of linearity between Faraday rotation and applied magnetic field are investigated. With a method requiring two nearly identical sensors, a very significant over-all improvement is achieved. A second method of compensation, which acts on the polarization of the incoming light, gives an improvement for low fields only. A slight mismatch between the two sensors may be almost completely offset by superimposing the first and second compensation methods.