Synaptic activity protects against AD and FTD-like pathology via autophagic-lysosomal degradation.

Changes in synaptic excitability and reduced brain metabolism are among the earliest detectable alterations associated with the development of Alzheimer's disease (AD). Stimulation of synaptic activity has been shown to be protective in models of AD beta-amyloidosis. Remarkably, deep brain stimulation (DBS) provides beneficial effects in AD patients, and represents an important therapeutic approach against AD and other forms of dementia. While several studies have explored the effect of synaptic activation on beta-amyloid, little is known about Tau protein. In this study, we investigated the effect of synaptic stimulation on Tau pathology and synapses in in vivo and in vitro models of AD and frontotemporal dementia (FTD). We found that chronic DBS or chemically induced synaptic stimulation reduced accumulation of pathological forms of Tau and protected synapses, while chronic inhibition of synaptic activity worsened Tau pathology and caused detrimental effects on pre- and post-synaptic markers, suggesting that synapses are affected. Interestingly, degradation via the proteasomal system was not involved in the reduction of pathological Tau during stimulation. In contrast, chronic synaptic activation promoted clearance of Tau oligomers by autophagosomes and lysosomes. Chronic inhibition of synaptic activity resulted in opposite outcomes, with build-up of Tau oligomers in enlarged auto-lysosomes. Our data indicate that synaptic activity counteracts the negative effects of Tau in AD and FTD by acting on autophagy, providing a rationale for therapeutic use of DBS and synaptic stimulation in tauopathies.

Sclerotic fibroma-like dermatofibroma: an uncommon distinctive variant of dermatofibroma.

Dermatofibroma (DF) is a common benign cutaneous tumor with many variants based on alterations in the morphology and composition of its diverse elements. One very infrequent type is sclerotic fibroma-like DF (SF-DF). We report 7 new cases of SF-DF. In addition, their main clinicopathological and immunohistochemical features were compared with 14 unselected common DFs and with 3 sclerotic fibromas (SFs). Microscopically, the 7 cases of SF-DFs showed an unencapsulated, well-circumscribed, hypocellular central nodule with thick collagen bundles arranged in a storiform pattern with prominent clefts. The overlying epidermis was attenuated. The periphery of this nodule was more cellular with histopathologic features of common DF. The 7 SF-DFs patients were 4 women and 3 men with a mean (+/-SD) age of 44.8 (+/-15.5) years. These 7 patients were younger than those suffering from SFs [71.0 (+/-17.3) years; (p=0.04)] and older than those presenting common DFs [30.5 (+/-12.3) years; (p=0.03)]. Immunohistochemically, spindle cells in all 7 SF-DFs were negative for CD34 and CD99. On the contrary, the 3 cases of SF were positive for CD34 and CD99. All of the common DFs were negative for CD34 and only 4 (28.6%) of them were positive for CD99. In conclusion, SF-DF is an uncommon variant of DF with similar clinicopathological and immunohistochemical features. SF-DF shares certain histopathologic features with SF but they are immunophenotypically different. Therefore, both entities should be differentiated.

Use of computer-aided detection (CAD) tools in screening mammography: a multidisciplinary investigation.

We summarise a set of analyses and studies conducted to assess the effects of the use of a computer-aided detection (CAD) tool in breast screening. We have used an interdisciplinary approach that combines: (a) statistical analyses inspired by reliability modelling in engineering; (b) experimental studies of decisions of mammography experts using the tool, interpreted in the light of human factors psychology; and (c) ethnographic observations of the use of the tool both in trial conditions and in everyday screening practice. Our investigations have shown patterns of human behaviour and effects of computer-based advice that would not have been revealed by a standard clinical trial approach. For example, we found that the negligible measured effect of CAD could be explained by a range of effects on experts' decisions, beneficial in some cases and detrimental in others. There is some evidence of the latter effects being due to the experts using the computer tool differently from the intentions of the developers. We integrate insights from the different pieces of evidence and highlight their implications for the design, evaluation and deployment of this sort of computer tool.

Elicitation and representation of expert knowledge for computer aided diagnosis in mammography.

OBJECTIVES: To study how professional radiologists describe, interpret and make decisions about micro-calcifications in mammograms. The purpose was to develop a model of the radiologists' decision making for use in CADMIUM II, a computerized aid for mammogram interpretation that combines symbolic reasoning with image processing. METHODS: In Study 1, eleven radiologists were asked to 'think out loud' as they interpreted 20 sets of calcifications. Participants used 159 terms to describe calcifications. We used these data to design a scheme with 50 descriptors. In Study 2, ten radiologists used the scheme to describe 40 sets of calcifications. We assessed the capacity of the terms to discriminate between benign and malignant calcifications, testing them against radiologists' assessments of malignancy and follow-up data. RESULTS: The descriptors that were found to be the most discriminating in Study 2 were included in CADIMUM II's knowledge base. They were represented as arguments for either a benign or a malignant diagnosis. These arguments are the central component of the decision support provided by the system. Other components are: image processing algorithms for the detection and measurement of calcifications and a set of rules that use the measures to decide which of the arguments apply to a given set of calcifications. CONCLUSIONS: Preliminary evaluations of the CADMIUM II prototype reinforce the value of representing explicitly decision making processes in computer aided mammography and of deriving these processes from image processing measurements. Decision support is presented here at a level of description that is both relevant and meaningful to the user.

Eliciting a terminology for mammographic calcifications.

AIM: Two studies were carried out to establish, validate and assess descriptors for use in the differential diagnosis for mammographic calcifications. METHODS: In Study 1, eleven radiologists were asked to 'think out loud' as they interpreted 20 sets of calcifications. Participants used 159 terms to describe calcifications. We used this data to design a scheme with 50 descriptors. In Study 2, ten radiologists used the scheme to describe 40 sets of calcifications. We assessed the capacity of the terms to discriminate between benign and malignant calcifications, testing them against radiologists' assessments of malignancy and follow-up data. RESULTS: All descriptors were used by at least 5 radiologists. Five additional descriptors were required. With some exceptions, properties that discriminated between benign and malignant outcomes were highly correlated with radiologists' assessment of risk. Many descriptors have a fairly low sensitivity but high specificity. CONCLUSIONS: Our data suggest that radiologists consider a wide range of features than is included in existing reporting schemes. Our scheme allows a richer characterization of calcifications, potentially improving the reporting and understanding of these abnormalities.

Evidence for pigment epithelium-derived factor receptors in the neural retina.

PURPOSE: The neurotrophic activity of pigment epithelium-derived factor (PEDF), an extracellular factor present in the retina, is mediated by binding to cell-surface receptors in responsive cell cultures. In the present study, the expression of PEDF receptors in native neural retinas from adult steers was examined. METHODS: Binding reactions were performed with (125)I-PEDF and fluoresceinated PEDF using plasma membranes, detergent-soluble membrane proteins, or cryosections of retina from adult bovine eyes. Radioligand-binding and competition analyses were performed with a computer-assisted program. Ligand blot analysis of detergent-soluble membrane proteins was performed with (125)I-PEDF followed by autoradiography. Ligand-affinity column chromatography of detergent-soluble membrane proteins was performed with PEDF-coupled resin followed by SDS-PAGE. Binding of fluoresceinated PEDF to retina cryosections was detected by confocal microscopy. RESULTS: Radioligand-binding assays showed that (125)I-PEDF bound in a specific and saturable fashion to one class of sites on retina membranes (K(d) = 2.5-6.5 nM; maximum binding [B(max)] = 1-48 x 10(10) sites/retina). A peptide of 44 amino acids (44-mer), identified as the receptor-binding region of PEDF, competed efficiently for (125)I-PEDF binding to retina membranes with kinetics similar to the full-length PEDF. Ligand blot analysis and ligand-affinity chromatography revealed a specific and high-affinity PEDF-binding protein of approximately 85 kDa in retina plasma membranes. Confocal microscopy showed that fluorescein-conjugated PEDF stained exclusively the inner segments of photoreceptors and cells of the ganglion cell layer in retinal cryosections. CONCLUSIONS: Altogether, these data conclusively demonstrate the existence of PEDF receptors discretely distributed on the surface of cells from the adult neural retina of bovine eyes. Furthermore, they provide evidence for the direct action of PEDF on photoreceptor and ganglion cell neurons and an anatomic basis for studies to assess PEDF neurotrophic effects on the adult retina.

Combining decision support and image processing: a PROforma model.

This paper addresses two important problems in medical image interpretation:(1) integration of numeric and symbolic information, (2) access to external sources of medical knowledge. We have developed a prototype in which image processing algorithms are combined with symbolic representations for reasoning, decision making and task management in an integrated, platform-independent system for the differential diagnosis of abnormalities in mammograms. The prototype is based on PROforma, a generic technology for building decision support systems based on clinical guidelines. The PROforma language defines a set of tasks, one of which, the enquiry, is used as means of interaction with the outside world. However, the current enquiry model has proved to be too limited for our purposes. In this paper we outline a more general model, which can be used as an interface between symbolic functions and image or other signal data.

CADMIUM II: acquisition and representation of radiological knowledge for computerized decision support in mammography.

CADMIUM II is a system for the interpretation of mammograms. A novel aspect of the system is that it combines symbolic reasoning with image processing, in contrast with most other approaches, which use only image processing and rely on artificial neural networks (ANNs) to classify mammograms. A problem of ANNs is that the advice they give cannot be traced back to communicable diagnostic inferences. Our approach is to provide advice based on explicit knowledge about the diagnostic process. To this end, we have conducted a knowledge elicitation study which looked at the descriptors used by expert radiologists when making diagnostic decisions about mammograms. The analysis of the radiologists' reports yielded a set of salient diagnostic features. These were used to inform the advice provided by the symbolic decision making component of CADMIUM II.

Binding of pigment epithelium-derived factor (PEDF) to retinoblastoma cells and cerebellar granule neurons. Evidence for a PEDF receptor.

Pigment epithelium-derived factor (PEDF) has neuronal differentiation and survival activity on retinoblastoma and cerebellar granule (CG) cells. Here, we investigated the presence of PEDF receptors on retinoblastoma Y-79 and CG cells. PEDF radiolabeled with (l25)I remained biologically active and was used for radioligand binding analysis. The binding was saturable and specific to a single class of receptors on both cells and with similar affinities (K(d) = 1.7-3.6 nM, B(max) = 0.5-2.7 x 10(5) sites/Y-79 cell; and K(d) = 3.2 nM, B(max) = 1.1 x 10(3) sites/CG cell). A polyclonal antiserum to PEDF, previously shown to block the PEDF neurotrophic activity, prevented the (125)I-PEDF binding. We designed two peptides from a region previously shown to confer the neurotrophic property to human PEDF, synthetic peptides 34-mer (positions 44-77) and 44-mer (positions 78-121). Only peptide 44-mer competed for the binding to Y-79 cell receptors (EC(50) = 5 nM) and exhibited neuronal differentiating activity. PEDF affinity column chromatography of membrane proteins from both cell types revealed a PEDF-binding protein of approximately 80 kDa. These results are the first demonstration of a PEDF-binding protein with characteristics of a PEDF receptor and suggest that the region comprising amino acid positions 78-121 of PEDF might be involved in ligand-receptor interactions.

Contribution of phosphodiesterase isoenzymes and cyclic nucleotide efflux to the regulation of cyclic GMP levels in aortic smooth muscle cells.

Involvement of phosphodiesterase isoenzymes (PDEs) in guanosine-3',5'-cyclic monophosphate (cGMP) hydrolysis was analyzed in aortic smooth muscle cells. Four families of PDEs were separated from pig aorta: PDE1 (calcium-calmodulin-activated), PDE3 (cGMP-inhibited), PDE4 (adenosine 3',5'-cyclic monophosphate [cAMP]-specific), and PDE5 (cGMP-specific). Within this PDE complement, PDE1 and PDE5 mostly contributed to the hydrolysis of cGMP both in the presence and absence of calcium-calmodulin. The role of these isoenzymes in cGMP degradation was analyzed in primary cultures of porcine aortic smooth muscle cells after stimulation with sodium nitroprusside (SNP) or atrial natriuretic factor (ANF). Pretreatment with 10 microM zaprinast, a concentration that selectively inhibits PDE5, did not potentiate the SNP- or ANF-induced rise of cGMP, questioning the widespread opinion that only PDE5 accounts for cGMP hydrolysis in this tissue. Further evidence came from experiments assessing the effect of zaprinast or 3-isobutyl-1-methylxanthine at concentrations inhibiting both type 1 and type 5 isoenzymes, in which this potentiation was clearly seen. Contribution of cGMP egression to the control of intracellular cGMP levels after SNP or ANF stimulation was also investigated. Shortly after guanylate cyclase activation, extracellular cGMP levels surpassed intracellular levels. However, comparison of the amounts of cGMP extruded to the extracellular medium with those degraded by PDEs leads to the conclusion that efflux is of relatively minor importance in regulating intracellular cGMP levels. In cells made tolerant to SNP, selective PDE5 inhibition synergistically increased intra- and extracellular cGMP amounts after SNP stimulation. These results indicate a previously undescribed greater relevance of PDE5 after tolerance development in aortic smooth muscle cells.

Pigment epithelium-derived factor promotes the survival and differentiation of developing spinal motor neurons.

Pigment epithelium-derived factor (PEDF) is a member of the serine protease inhibitor (serpin) superfamily that has been shown previously to promote the survival and/or differentiation of rat cerebellar granule neurons and human retinoblastoma cells in vitro. However, in contrast to most serpins, PEDF has no inhibitory activity against any known proteases, and its described biological activities do not appear to require the serpin-reactive loop located toward the carboxy end of the polypeptide. Because another serpin, protease nexin-1, has been shown to promote the in vivo survival and growth of motor neurons, the authors investigated the potential neurotrophic effects of PEDF on spinal cord motor neurons in highly enriched cultures and in vivo after injury. Here, it is shown that native bovine and recombinant human PEDF promoted the survival and differentiation (neurite outgrowth) of embryonic chick spinal cord motor neurons in vitro in a dose-dependent manner. A truncated form of PEDF that lacks approximately 62% of the carboxy end of the polypeptide comprising the homologous serpin-reactive loop also exhibited neurotrophic activities similar to those of the full-length protein. Furthermore, the data here showed that PEDF was transported retrogradely and prevented the death and atrophy of spinal motor neurons in the developing neonatal mouse after axotomy. These results indicate that PEDF exerts trophic effects on motor neurons, and, together with previous reports, these findings suggest that this protein may be useful as a pharmacologic agent to promote the development and maintenance of motor neurons. J. Comp. Neurol. 412:506-514, 1999. Published 1999 Wiley-Liss, Inc.

[Epidemic outbreak of acute food poisoning caused by pesticides]. / Brote epidémico de intoxicación aguda alimentaria por plaguicidas.

OBJECTIVES: 1) To identify the causes of the outbreak. 2) To adopt the appropriate measures to control it. DESIGN: Observational crossover study. SETTING: San Benito Health District in Jerez de la Frontera (Cádiz). PATIENTS AND OTHER PARTICIPANTS: Diners who attended a family celebration. MEASUREMENTS AND MAIN RESULTS: On Friday 11th March 1994 there was an outbreak of acute food poisoning. The clinical notes of 9 ill diners were checked; they and 7 unaffected diners answered epidemiological questionnaires. A proportional comparison was then made between those not exposed and those exposed to each one of the foods consumed at this celebration. The clinical picture showed: high level of the Creatine phosphokinase enzyme, general myalgias, vomiting or nausea and visual problems. The average incubation period was 7 hours. The odds ratios of the foods involved was calculated. Although this reached 4 in some cases, the significance tests were not significant in any case because of the study's low statistical power. In the investigation of the trophic chain of the game-birds eaten, the presence of nitrogen or phosphorus atoms, compatible with the pattern of fonofos in the pesticide used on the hunting estate where the birds came from, was isolated. CONCLUSIONS: Epidemiological, clinical and biological evidence was found, which places us before acute organophosphorus poisoning. Coordination between the different institutions involved was decisive in finding the cause of the outbreak.

Inotropic and chronotropic effects of 4-(4'-n-butylaniline)-7,8- dimethoxy-5H-pyrimido[5,4-b]indole in guinea-pig atria.

Cardiotonic effect of 4-(4'-n-butylaniline)-7,8-dimethoxy- 5H-pyrimido[5,4-b]indole (B11) was investigated in isolated cardiac tissue preparations. The action of this agent on force of contraction, beating frequency and cyclic nucleotide phosphodiesterase (PDE) activity was studied. Amrinone was used for comparison. B11 produced concentration-dependent (5 x 10(6)-1 x 10(-4)M) positive inotropic and positive chronotropic responses in guinea-pig atrial tissues. The potency of B11 was greater than that of amrinone. The cardiotonic effects of B11 were not modified by beta-adrenoceptor blockade. Carbachol inhibited the positive inotropic effect of B11. The activity of B11 was increased in desensitized left atrial tissues. B11 inhibited the activities of PDE isoenzymes (type I, II, IV and V) from dog heart ventricle and PDE type IV from guinea-pig heart ventricle nonselectively. It is concluded that B11 possesses potent positive inotropic activity in guinea-pig atria, and the effect is probably mediated by a non-selective inhibition of PDE activity.

New indole and triazino[5,4-b]indol-4-one derivatives: synthesis and studies as inotropics and inhibitors of blood platelet aggregation.

New triazino[5,4-b]indol-4-one derivatives carrying amino groups in position 3 were synthetized and tested as inotropic agents and inhibitors of platelet aggregation. 2h, 2p, 5p, and 6g are the most active as inotropic agents. Compounds were tested as inhibitors of platelet aggregation induced by adenosine 5'-diphosphate (ADP) and arachidonic acid (AA) (guinea pig whole blood). 2k, 2p, 5o, 6d, 6m, and 6o are the most active as inhibitors of the platelet aggregation induced by AA. 6d, 6h, and 6o are most active compounds also in the aggregation induced by ADP. Radioimmunoassay studies, following AA induced aggregation, measuring thromboxane B2 (TXB2) and prostaglandin E2 (PGE2) were carried out on compounds 2b, 2d, 2f, 2g, 2h, 2i, 2k, 2m, 2o, 2p, 2r, 5i, 5j, 5k, 5r, and 5f, which inhibit platelet aggregation induced by AA. None of the compounds tested turned out to be selective inhibitors. Compounds 2h and 2p showed both inotropic and platelet aggregation inhibiting activity.