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At least 19 recordsLinked to original sources
PubMed1991

Differential expression of beta amyloid protein precursor (APP) and tau mRNA in the aged human brain: individual variability and correlation between APP-751 and four-repeat tau.

We investigated the relationship between the differential expression of beta amyloid protein precursor (APP) and tau mRNA, and the extent of beta and tau deposition in three regions from each of the 38 aged brains obtained from consecutive autopsied cases. Remarkable variabilities were noted in the ratios of APP-770/-751/-695 and four-repeat tau among elderly individuals. There was no consistent alteration in the APP differential expression among beta plaque (-), (+), and (++(-) ) groups. Also, no differences in the four-repeat tau ratios were noted among tangle (-), (+), and (++) groups. Despite these great individual variabilities, APP-751 was found to be well-correlated with four-repeat tau. It is possible that APP-751 and four-repeat tau are increasing during aging, while APP-695 and three-repeat tau are decreasing.

Aged↗
PubMed1990

Amyloid beta-protein precursor (APP) of cultured cells: secretory and non-secretory forms of APP.

Overproduction or aberrant catabolism of the predicted amyloid beta-protein precursor (APP) is suspected as the cause of amyloid deposition in Alzheimer's disease and Down's syndrome brains. For possible in vitro experiments of amyloid formation, we have examined the expression of APP in various cultured cells. We found two types of APP producing cell lines. PC12h (rat pheochromocytoma) and HL-60 (human acute promyelocytic leukemia) cells produce a secretory form that is released into the culture medium, while Bu-17 (human glioma) cells synthesize only a non-secretory form that accumulates at the cell surface. APP immunoreactivity on the latter cells was detected at the tips of cell processes or growth cones. These observations indicate that the nonsecretory form of APP may play a role in cell contact or adhesion.

Alzheimer Disease↗
PubMed2026

Smartphone Apps for Preventing Adolescent Health Problems Among Health Care Professionals: Systematic Search and Quality Assessment.

BACKGROUND: Health care professionals must consider multiple dimensions of prevention when consulting with adolescents. Identifying risky behaviors early in adolescence is crucial for reducing both morbidity and mortality. General practitioners are increasingly eager to incorporate digital tools for prevention into their consultations with adolescents; however, the relevance and clinical validity of these digital tools are not always established or well-known. Consequently, primary care professionals require guidance and support in selecting relevant mobile health (mHealth) tools. OBJECTIVE: The aim of this study is to identify relevant and useful digital apps to help primary care professionals detect at-risk adolescents across all recommended areas of prevention: orthopedics, mental health, substance abuse, risk behaviors, sexual health, vaccinations, social relationships, and nutrition. METHODS: A systematic review of smartphone apps, with an analysis of content quality, was carried out by 4 researchers using the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) checklist. The App Store and Google Play Store platforms were surveyed. The inclusion criteria were as follows: free of charge, date of last update, availability in French or English, relevance of the preventive approach to adolescents, and scientific validation. Four health care professionals assessed the apps: 2 selected the apps relevant to health care professionals, then 3 analyzed these apps using the French version of the Mobile App Rating Scale (MARS-F). Intraclass correlation coefficient, model (2,1) (2-way random effects, absolute agreement, single measures); standard error of measurement; and mean absolute error were also calculated. RESULTS: A total of 976 apps were identified, 49 of which had disappeared from the platforms prior to analysis. Nine apps were retained. Seven (0.72%) were included after evaluation using the MARS-F: 2 on mental health and 5 on sexual health (including 3 on contraception only). The mean MARS-F interrater score ranged from 2.5/5 to 3.8/5. The global MARS-F score demonstrated a pooled SD of 0.60 and an intraclass correlation coefficient (2,1) of 0.0003, resulting in a calculated standard error of measurement of 0.60. The average discrepancy between raters was a mean absolute error of 0.53. CONCLUSIONS: No similar studies have been identified in the literature that specifically focus on mobile apps designed to support health care professionals in delivering preventive care to adolescents. Of the 8 areas of prevention identified as relevant for adolescents, only 3 are addressed by the apps validated through our methodology (5 focus on sexual health). Consequently, current apps are insufficient to support health care professionals in their overall preventive work with adolescents. Such a review should be conducted systematically prior to the development of any new tool to prevent duplication and channel creative efforts toward truly innovative digital solutions. Furthermore, a thorough analysis of relevant, recommended websites is essential, as these resources complement the use of mobile apps designed for health care professionals.

Humans↗
PubMed1992

Role of amyloid precursor protein (APP): study with antisense transfection of human neuroblastoma cells.

The function of amyloid precursor protein (APP) was investigated in human neuroblastoma La-N-1 cells by stable transfection with a DNA construct encoding antisense APP mRNA. Levels of APP mRNA, as well as proteins, were reduced by 80-90% in antisense APP transfected (ASAT) cells. ASAT cells exhibited three main features as a result of APP gene expression deprivation: (1) a 30% reduction in cell proliferation, (2) reduced cell adhesion that could be reversed by the addition of La-N-1 conditioned media as a source of secreted APP, and (3) a two- and four-fold increase in neurite-bearing cells suggesting that cellular APP may be involved in neurite extension. The first two features confirm previously reported functions for APP in proliferation and adhesion of non-neuronal cell types but the use of neuroblastoma cells in this study disclose a novel role for cellular APP in neurite extension.

Amyloid beta-Protein Precursor↗
PubMed1992

Identification and differential expression of a novel alternative splice isoform of the beta A4 amyloid precursor protein (APP) mRNA in leukocytes and brain microglial cells.

The gene for the beta A4-amyloid precursor protein (APP) consists of 19 exons which code for a typical N- and O-glycosylated transmembrane protein with four extracellular domains followed by the transmembrane domain and a short cytoplasmic domain. The beta A4-amyloid sequence is part of exons 16 and 17. Several APP isoforms can be generated by alternative splicing of exons 7 and 8, encoding domains with homologies to Kunitz-type protease inhibitors and the MRC OX-2 antigen, respectively. The mechanism by which the pathological beta A4 is generated is unknown, it is however a critical event in Alzheimer's disease and is distinct from the normally occurring cleavage and secretion of APPs within the beta A4 sequence. We report here for the first time considerable APP mRNA expression by rat brain microglial cells. In addition we showed by S1 nuclease protection and polymerase chain reaction analysis of reverse transcribed RNA (RT-PCR) that T-lymphocytes, macrophages, and microglial cells expressed a new APP isoform by selection of a novel alternative splice site and exclusion of exon 15 of the APP gene. This leads to a transmembrane, beta A4 sequence containing APP variant, lacking 18 amino acid residues close to the amyloidogenic region. The use of this novel alternative splice site alters the structure of APP in close proximity to the beta A4 region and thus may determine a variant, potentially pathogenic processing of leukocyte-derived APP in brain.

Amyloid beta-Protein Precursor↗
PubMed1991

Expression patterns of beta-amyloid precursor protein (beta-APP) in neural and nonneural human tissues from Alzheimer's disease and control subjects.

Both neural and nonneural human tissues from patients with or without Alzheimer's disease (AD) were surveyed to detect the presence of the beta-amyloid protein and its precursors. This was accomplished using polyclonal and monoclonal antibodies to epitopes in the 695 amino acid long beta-APP (i.e., beta-APP695), as well as in related beta-APPs. Immunoreactivity in beta-APP in brain was prominent in senile plaques, extraneuronal tangles, and neurons. Outside the brain, beta-APP staining was seen in neurons and satellite glial cells of the dorsal root, enteric and trigeminal ganglia, the adeno- and neurohypophysis, megakaryocytes, and adrenal gland in samples from patients with AD and those without AD. Western blots of neocortex revealed three major proteins with apparent molecular masses of 105, 115, and 125 kDa in the insoluble membrane-associated fractions, while two broad bands with a molecular weight centered at about 100 and 120 kDa were detected in soluble fractions. In addition, the pituitary and adrenal glands as well as cardiac muscle revealed prominent immunobands in membrane-associated fractions. Notably, other nonneural tissues were devoid of beta-APP immunoreactivity. Thus, the beta-APPs are detectable only in a limited number of nonneural tissues. Taken together, these data suggest that beta-APPs produced in the brain are sources of beta-APP peptides that accumulate as senile plaques in AD.

Alzheimer Disease↗
PubMed1991

Regulatory region of human amyloid precursor protein (APP) gene promotes neuron-specific gene expression in the CNS of transgenic mice.

The accumulation of beta-amyloid protein in specific brain regions is a central pathological feature of Alzheimer's disease (AD). The 4 kd beta-amyloid protein derives from a larger amyloid precursor protein (APP) by as yet unknown mechanisms. In the absence of a laboratory animal model of AD, transgenic mice expressing various APP gene products may provide new insights into the relationship between APP and beta-amyloid formation and the pathogenesis of AD. beta-amyloid accumulation in AD brain may result from interactions between APP and other molecules. Such interactions are likely to be developmentally regulated and tissue-specific. A transgenic mouse model of AD, therefore, would aim for APP transgene expression that mimics the endogenous APP gene. As an initial step in developing an animal model, we have identified a 4.5 kb DNA fragment from the 5' end of the human APP gene, which mediates neuron-specific gene expression in the CNS of transgenic mice, using E. coli lacZ as a reporter gene. Detectable levels of transgene expression are found in most neurons but not in glial and vascular endothelial cells. The expression pattern of this reporter gene closely resembles the distribution of endogenous APP mRNA in both the human and mouse CNS.

Alzheimer Disease↗
PubMedDate not supplied

APP-collagen interaction is mediated by a heparin bridge mechanism.

The amyloid precursor protein (APP) is a glycoprotein consisting of at least four isoforms derived from a single gene by a process of alternative splicing. The membrane-bound forms of APP have been suggested to have adhesive properties and to mediate neural cell adhesion. Previous studies have demonstrated the ability of Fab' fragments of antibodies to extracellular domains of APP to inhibit neural cell binding to a collagen substrate, suggesting a physiological role for the collagen-binding properties of APP. The binding of APP has been demonstrated to be specific for type IV collagen, and no binding to other extracellular matrix components, including fibronectin and laminin, was detected. The APP-collagen binding appeared to be mediated by a heparin-bridge mechanism, since the binding was abolished by the addition of excess heparan or heparinase. These results were observed by both a homogenate-collagen binding assay and a cell-surface adhesion assay, thus providing further evidence for the adhesion role of APP. They also pose the question of the possible role of the heparin-binding properties of APP in the genesis of the neuritic plaques characteristic of Alzheimer's disease.

Alzheimer Disease↗
PubMed1992

The effect of C-terminus and N-terminus iodination on avian pancreatic polypeptide (APP) binding to its chicken brain receptor.

In previous studies, membranes from chicken gastrointestinal tissues failed to bind appreciable levels of 125I-APP labeled at the C-terminus. In order to address the suggestion that this was due to steric hindrance of the critical C-terminus, N-terminally labeled 125I-APP was utilized in in vitro membrane binding assays. Membranes from chicken cerebellum and spleen specifically bound N-terminally iodinated APP, while those from gastrointestinal tissues including pancreas, mucosal and muscle layers of duodenum and proventriculus did not. Cerebral cortex membranes also failed to specifically bind Bolton-Hunter labeled 125I-APP. Liver membranes, which previously were shown to bind C-terminally iodinated APP with low affinity, also did not specifically bind N-terminally labeled preparations. It is concluded that the inability of membranes from gastrointestinal tissues and brain regions other than cerebellum to bind 125I-APP is not an artifact of location of iodine placement on the molecule and that both the N- and C-termini may be important for receptor binding. It is also concluded that liver APP binding sites may be structurally distinct from those in the cerebellum, and that gastrointestinal tissues may not be direct targets for APP action.

Animals↗
PubMedDate not supplied

APP-695 transcript prevalence is selectively reduced during Alzheimer's disease in cortex and hippocampus but not in cerebellum.

We previously found a selective loss of the brain specific APP-695 transcript in Alzheimer's disease (AD) cortex, which results in a 2.5-fold increase in the APP-751/APP-695 transcript ratio in AD (9). Here we report a similar increase in APP-751/APP-695 mRNA ratio in AD hippocampus. However, the cerebellum had a 6-fold lower ratio, which does not change in AD. The APP-695 mRNA species is greatly decreased (3-4-fold) in mRNA from AD cortex and hippocampus, whereas the APP-751 mRNA species is essentially unchanged. Considering hippocampal neuron loss and cortical neuron loss and atrophy, the data presented may be compatible with increased APP-751 mRNA and decreased APP-695 mRNA prevalence in remaining neurons in AD. A possible relationship between a high APP-751/APP-695 ratio and amyloid pathology is discussed.

Adult↗
PubMed2026

Smartphone apps for obesity management: A systematic review using self-determination theory.

BACKGROUND: While bariatric surgery and pharmacotherapy are effective treatments for obesity, ongoing supportive care remains a challenge. Smartphone applications (apps) may assist with symptom management, but their effectiveness and practical use in obesity treatment is unclear. This review evaluated the effectiveness, acceptability, and feasibility of these apps in supporting individuals following obesity treatment. To better understand how these apps may promote sustained engagement and behaviour change, their design was analysed using Self-Determination Theory (SDT). METHODS: A systematic search was conducted across MEDLINE, Embase, PsycINFO, CINAHL, Web of Science, SCOPUS, and CENTRAL databases. Eligible studies included randomised and non-randomised interventions involving adults (≥18 years) with obesity (BMI ≥ 30 kg/m2) who had undergone bariatric surgery or pharmacotherapy. Interventions had to include an app designed to support post-treatment symptom management. Findings were synthesised narratively, and app features were mapped to SDT constructs of autonomy, competence, and relatedness. RESULTS: Five studies (three RCTs, two cohort studies) involving 1,133 participants were included (female: 78 %; median age: 47.63 years). Most apps targeted post-bariatric surgery care; only one focused on pharmacotherapy. Common features included tracking, reminders, and education, supporting autonomy and competence. Relatedness features such as communication and peer support were least represented. Two studies reported improvements in weight-related outcomes and one in medication adherence. Effects on quality of life, self-efficacy, and healthcare utilisation were not significant. Patient satisfaction was reported in one study, with 95 % expressing positive feedback, though formal assessments of feasibility and acceptability were limited. CONCLUSION: Smartphone apps show potential to support obesity management, particularly after bariatric surgery. While some evidence suggests benefits for weight loss and adherence outcomes, the limited studies and variability of reporting prevent conclusive observations in other outcomes. Future app development should integrate behavioural theory to address psychological needs, nutritional risks and promote holistic self-management beyond weight control.

Female↗
PubMed1992

Linkage and mutational analysis of familial Alzheimer disease kindreds for the APP gene region.

A large number of familial Alzheimer disease (FAD) kindreds were examined to determine whether mutations in the amyloid precursor protein (APP) gene could be responsible for the disease. Previous studies have identified three mutations at APP codon 717 which are pathogenic for Alzheimer disease (AD). Samples from affected subjects were examined for mutations in exons 16 and 17 of the APP gene. A combination of direct sequencing and single-strand conformational polymorphism analysis was used. Sporadic AD and normal controls were also examined by the same methods. Five sequence variants were identified. One variant at APP codon 693 resulted in a Glu-->Gly change. This is the same codon as the hereditary cerebral hemorrhage with amyloidosis-Dutch type Glu-->Gln mutation. Another single-base change at APP codon 708 did not alter the amino acid encoded at this site. Two point mutations and a 6-bp deletion were identified in the intronic sequences surrounding exon 17. None of the variants could be unambiguously determined to be responsible for FAD. The larger families were also analyzed by testing for linkage of FAD to a highly polymorphic short tandem repeat marker (D21S210) that is tightly linked to APP. Highly negative LOD scores were obtained for the family groups tested, and linkage was formally excluded beyond theta = .10 for the Volga German kindreds, theta = .20 for early-onset non-Volga Germans, and theta = .10 for late-onset families. LOD scores for linkage of FAD to markers centromeric to APP (D21S1/S11, D21S13, and D21S215) were also negative in the three family groups. These studies show that APP mutations account for AD in only a small fraction of FAD kindreds.

Adult↗
PubMed1992

Beta/A4 domain of APP: antigenic differences between cell lines.

The expression of amyloid precursor protein (APP) in olfactory neuroblasts has been examined with a panel of antibodies directed against varied regions of the APP molecule. The pattern of reactivity was compared to that in the transformed human glial cell line SVG, human cortical brain tissue, and in kidney epithelial 293 cells containing stably transfected and overexpressed human APP751. Antibodies directed against the C-terminus and extracellular domains of amyloid precursor protein (APP) react more strongly on immunoblot with transfected 293 cells and brain tissue than with olfactory neuroblasts (ON) or SVG cells. Antibodies directed against the beta/A4 region of APP show a contrasting pattern of reactivity, yielding greater reactivity with ON and SVG cells than with transfected 293 cells or brain tissue. Analysis of the APP transcripts using polymerase chain reaction indicates that ON and SVG both make predominantly APP770 and 751, as does the transfected 293 cell line. In the absence of any differences in APP transcripts among the cell lines, the difference in availability of the beta/A4 region appears likely to be due to posttranslational modification. These data therefore indicate that processing of APP varies among cell lines and thus may vary from tissue to tissue.

Amyloid beta-Protein Precursor↗
PubMed1991

Alzheimer's disease amyloid beta-clipping enzyme (APP secretase): identification, purification, and characterization of the enzyme.

Alzheimer's disease (AD) is the most frequent cause of dementia, although no genetic abnormality has been identified. Recent studies have elucidated the molecular defect in AD, including the abnormal deposition of amyloid beta peptide (beta/A4) in senile plaques of affected individuals. Normal brain contains the enzyme, APP secretase, which cleaves inside the beta/A4 portion of the precursor protein (APP); abnormal processing of APP occurs in AD brain. Until now, no evidence has been provided that APP secretase is an intracellular proteinase. We have now prepared two synthetic substrates of APP secretase, both of which contain the cleavage point and are much more sensitive than substrates previously available to identify APP secretase. Using these substrates, we found an intracellular proteinase that has APP secretase activity. This proteinase has been identified as cathepsin B.

Alzheimer Disease↗
PubMed1992

Species specificity and developmental patterns of expression of the beta amyloid precursor protein (APP) gene in brain, liver and choroid plexus in birds.

1. Human APP cDNA hybridized to a 3.5 kb mRNA in liver and brain RNA from chickens, pigeons, quail and ducks as well as in RNA from choroid plexus of chicken and quail. In contrast to all other species hitherto examined a 1.6 kb mRNA hybridizing to APP cDNA was found in abundant amounts in RNA from chicken and quail livers. 2. In the chicken, before hatching, the levels of APP mRNA in total RNA from liver and choroid plexus were higher than those in RNA from liver and choroid plexus of adults. However, RNA from the rest of the brain of chicken embryos contained less APP mRNA than RNA from brain of adults. 3. In the chicken, between 10 and 40 days after hatching, APP mRNA levels in RNA from liver were higher than adult levels, APP mRNA levels in RNA from choroid plexus were similar to adult levels and APP mRNA levels in RNA from the rest of brain were below the adult levels.

Amyloid beta-Peptides↗
PubMed1992

Comparative studies on the effect of 4-APP(4-aminopyrazolopyrimidine) on hamster and rat adrenal cortex.

The study aimed to compare, by means of stereologic methods, the reactivity of the adrenal cortex of the hamster and the rat to prolonged treatment with 4-aminopyrazolo-(3,4d)pyrimidine (4-APP), a drug reducing hepatic secretion of plasma lipoprotein. Adult female hamsters, intact or cortisone suppressed, were administered i.p. daily with 0.5 mg 4-APP for 5 days while intact female rats received 1 mg of the drug per dose. 4-APP resulted in a loss of body weight, with the more profound effect in the hamster. In the rat 4-APP did not change the adrenal gland weight, the volume of the adrenocortical zones, the average volume of adrenocortical cells and the number of parenchymal cells in the gland. Moreover, serum ACTH and corticosterone levels in the rat remained unchanged. In the intact hamster 4-APP decreased the adrenal gland weight, the volume of the zona fasciculata and enhanced the serum cortisol level. In steroid suppressed hamsters 4-APP lowered the adrenal weight, the volume of fasciculata and reticularis zones, the average volume of the fasciculata cells and the number of parenchymal cells in the gland. These findings may suggest the direct inhibitory effect of low 4-APP doses on the hamster adrenal cortex and clearly demonstrate higher susceptibility of the hamster adrenal cortex, if compared with the rat, to 4-aminopyrazolo-pyrimidine.

Adenine↗
PubMedDate not supplied

Positive inotropic and electrophysiological effects of APP 201-533 can be explained by an increase of cardiac cyclic AMP.

The possible mechanism of action of the positive inotropic agent APP 201-533 [3-amino-6-methyl-5-phenyl-2(1H)-pyridinone] was investigated. In guinea pig papillary muscles, APP 201-533 increased force of contraction concentration dependently at 10(-4)-10(-3) M. The effect was associated with an abbreviation of contraction and relaxation time. In guinea pig papillary muscles partially depolarized with 22 mM K+, APP 201-533 in concentrations of 10(-4) and 10(-5) M restored slow action potentials, which were not influenced by cimetidine, propranolol, and prazosin but were blocked by the Ca2+ antagonist PY 108-068 and by carbachol in an atropine-sensitive manner. The concentration-effect curve of histamine was shifted to the left in the presence of APP 201-533. These actions can be explained by the increase in cardiac cyclic AMP level that was found in rabbit papillary muscles and guinea pig left atria treated with APP 201-533 due to the known phosphodiesterase inhibitory effect of pyridinones. APP 201-533 increased the inotropic potency of dihydroouabain in guinea pig papillary muscles. It seems possible that this effect is based on an increased Ca2+ sensitivity of myocardial contractile structures as described previously for APP 201-533.

Action Potentials↗
PubMed1991

The promoter activity of the gene encoding Alzheimer beta-amyloid precursor protein (APP) is regulated by two blocks of upstream sequences.

Transcriptional regulation of the gene encoding the amyloid precursor protein (APP) may play an important role in the formation of the amyloid depositions observed in Alzheimer disease and Down syndrome patients. To determine the promoter sequence requirements for the expression of the APP gene, we constructed plasmids containing different parts of the APP gene promoter fused to the bacterial chloramphenicol acetyl transferase (CAT) gene. Transfection of these constructs into Hela and PC12 cells revealed the presence of two blocks of regulatory sequences in the APP promoter. One block extending from about -600 to -460 bp acts as a positive regulator as its removal results in a substantial decrease in promoter activity. A second block of sequences extending from -450 to -150 bp acts like a negative regulator. We have also observed that a 38 mer synthetic oligonucleotide encompassing the region -489 to -452 of the APP promoter stimulated the activity of the heterologous TK promoter, suggesting that this region may be part of an enhancer-like element. In addition, our results suggest that the effects of various APP promoter domains on its activity may be cell specific.

Alzheimer Disease↗