The mechanism(s) of cholesterol-effect on processing and transport of APP protein

Peptid amiloid-β (Aβ), središnja molekula u patogenezi Alzheimerove bolesti, nastaje amiloidogenim cijepanjem proteina APP β-sekretazom u endosomima, dok cijepanje proteina APP na staničnoj membrani α-sekretazom sprečava nastanak ovog patološkog peptida. Nakupljanje peptida Aβ u mozgu otkriveno je ne samo u Alzheimerovoj bolesti nego i u bolesti Niemann-Pick tipa C (NPC), nasljednoj neurodegenerativnoj bolesti nakupljanja lipida. U ovom radu smo pokazali da je povećana razina peptida Aβ u stanicama NPC posljedica povećanog cijepanja proteina APP enzimom β-sekretaza uzrokovanog nakupljanjem kolesterola. Nadalje, pokazali smo da je internalizacija proteina APP nužna za nastanak peptida Aβ, te da u stanicama NPC zbog nakupljanja kolesterola u kasnim endosomima / lizosomima dolazi do poremećaja u transportu proteina APP u endocitoznom putu. Naime, u stanicama NPC smo detektirali ubrzanu internalizaciju i usporeno recikliranje proteina APP na površinu stanice što uzrokuje njegovo nakupljanje u ranim / reciklirajućim endosomima, centralnom mjestu stvaranja peptida Aβ. Ovim istraživanjem smo pokazali da povišena razina kolesterola može biti pokretač patoloških procesa u Alzheimerovoj bolesti jer potiče smještaj proteina APP u endosomima što rezultira njegovim povećanim amiloidogenim cijepanjem i nastankom peptida Aβ

Croatian Dialectological Research – scera, danas, jutra

Hrvatska je dijalektologija 20. st. opisana kao genetskolingvistička disciplina; temelj je takvoga dijalektološkoga istraživanja mjesni govor. Hrvatski su dijalektolozi, u težnji za sustavnim prikazom hrvatskih organskih idioma, vođeni razlikovnim jezičnim činjenicama, usmjeravali svoje opise na nevarijabilne dijelove jezičnoga sustava orijentiravši se tako na strukturalistički pristup opisa mjesnoga govora kao homogenoga sustava. Odgovore na teorijske izazove na koje nailazi hrvatska dijalektologija 21. stoljeća možemo potražiti u metodama koje nam pružaju kvantitativna ili varijacijska sociolingvistika. Ono što se u hrvatskoj dijalektologiji još u potpunosti ne iskorištava jesu i mogućnosti koje u istraživanju svih jezičnih razina, ali i pristupu postojećih istraživanja i razmjeni podataka, može pružiti digitalna tehnologija.Croatian dialectology of the 20th century is defined as a discipline of genetic linguistics. The basis for this kind of research is organic idiom, a complete implementation of a linguistic system in a small space. In the pursuit of a systematic presentation of Croatian organic idioms the Croatian dialectologists focused on unvariable linguistic parts of system and on the structuralist approach to the description of the local idiom as a homogeneous system. The answers to the theoretical challenges encountered in Croatian dialectology of the 21st century can be found in the methods provided by quantitative or variational sociolinguistics. Also, Croatian dialectology does not fully exploit the opportunities offered by digital technology

Croatian dialectological reseearch - ščera, danas, jutra

Hrvatska je dijalektologija 20. st. opisana kao genetskolingvistička disciplina; temelj je takvoga dijalektološkoga istraživanja mjesni govor. Hrvatski su dijalektolozi, u težnji za sustavnim prikazom hrvatskih organskih idioma, vođeni razlikovnim jezičnim činjenicama, usmjeravali svoje opise na nevarijabilne dijelove jezičnoga sustava orijentiravši se tako na strukturalistički pristup opisa mjesnoga govora kao homogenoga sustava. Odgovore na teorijske izazove na koje nailazi hrvatska dijalektologija 21. stoljeća možemo potražiti u metodama koje nam pružaju kvantitativna ili varijacijska sociolingvistika. Ono što se u hrvatskoj dijalektologiji još u potpunosti ne iskorištava jesu i mogućnosti koje u istraživanju svih jezičnih razina, ali i pristupu postojećih istraživanja i razmjeni podataka, može pružiti digitalna tehnologija.Croatian dialectology of the 20th century is defined as a discipline of genetic linguistics. The basis for this kind of research is organic idiom, a complete implementation of a linguistic system in a small space. In the pursuit of a systematic presentation of Croatian organic idioms the Croatian dialectologists focused on unvariable linguistic parts of system and on the structuralist approach to the description of the local idiom as a homogeneous system. The answers to the theoretical challenges encountered in Croatian dialectology of the 21st century can be found in the methods provided by quantitative or variational sociolinguistics. Also, Croatian dialectology does not fully exploit the opportunities offered by digital technology

From the Phraseology of the Local Kajkavian Dialect of Đurđevac

U radu se, na temelju korpusa ekscerpiranog iz rječnika Opis i rječnik đurđevečkoga govora autora Jele Maresić i Vladimira Miholeka (2011), pomoću semantičko-konceptualnog pristupa analiziraju frazemi koji su grupirani u nekoliko koncepata: frazemi koji se odnose na čovjekov odnos prema jelu i piću (kojima je značenje frazema definirano glagolima jesti i piti), frazemi koji se odnose na čovjekovo stanje (kojima je značenje frazema definirano pridjevima pijan, žedan, gladan i sit) i frazemi koji se odnose na čovjekovu vanjštinu (kojima je značenje frazema definirano pridjevima mršav i debeo). Slijedeći postavke kognitivne semantike, nastojala se utvrditi motivacija frazema i sveza s frazemskim značenjem.Using the corpus excerpted from the dictionary Opis i rječnik đurđevečkoga govora [A Description and a Dictionary of the Local Kajkavian Dialect of Đurđevac] by Jela Maresić and Vladimir Miholek (2011), the paper adopts a conceptual semantic approach in order to analyze phraseological units grouped around several concepts: those related to human attitudes toward food and drink (the meaning of the phraseological unit is defined by the verbs to eat and to drink), those related to human condition (the meaning of the phraseological unit is defined by the adjectives drunk, thirsty, hungry, and full), and those related to human appearance (the meaning of the phraseological unit is defined by the adjectives thin and fat). In accordance with the cognitive semantics approach, an attempt is made to determine the motivation of phraseological units and the resultant meaning

Alzheimer’s disease: from molecular mechanism to early diagnosis

Alzheimerova bolest (AB) najčešći je oblik demencije. Iako je prošlo već sto godina od otkrića bolesti kao i otkrića glavnih patoloških lezija u mozgu bolesnika s AB, senilnih plakova i neurofi brilarnih snopića, još uvijek ne postoji primjerena terapija koja bi liječila bolest, usporila njenu progresiju ili spriječila njezin nastanak. S obzirom na to da promijenjen metabolizam prekursora proteina amiloid-β (APP) i promijenjena razina pepti da amiloid-β (Aβ) predstavljaju glavni uzrok nastanka Alzheimerove bolesti , razumijevanje njihovog mehanizma nastanka i razgradnje važno je za razvoj novih oblika liječenja ove bolesti . Razvoj novih dijagnosti čkih metoda koje će omogućiti rano i točno otkrivanje AB stoga je izuzetno važan. Smatra se da će razvoj bilo kojeg oblika intervencije AB imati najznačajniji učinak u najranijoj fazi bolesti kada promjene u mozgu nisu još tako značajne. Analiza razine triju proteina u likvoru (Aβ42, ukupnog tau i fosforiliranog oblika proteina tau) za sada je dala najbolje rezultate te je pokazala da se ovim testom mogu diferencijalno dijagnosti cirati osobe s AB, kao i nedementne osobe te osobe s blagim kogniti vnim poremećajem koje će u budućnosti napredovati u AB, stoga je cilj istraživanja biomarkera utvrditi promjene koje će otkriti AB u njenoj najranijoj fazi. Nadamo se da će različiti aspekti istraživanja Alzheimerove bolesti pridonijeti razvoju novih oblika liječenja i/ili prevencije ove još uvijek neizlječive bolesti .Alzheimer’s disease (AD) is the most common form of dementi a. Although the disease and its main pathological features, senile plaques and neurofi brillary tangles, have been discovered over 100 years ago, there is sti ll no adequate therapy that would treat, slow progression or prevent the genesis of Alzheimer’s disease. Since altered metabolism of the β-amyloid precursor protein (APP) and altered formati on of amyloid-β pepti de (Aβ) play a central role in the pathogenesis of Alzheimer’s disease, understanding their mechanism of formati on and clearance is important for designing new therapies for AD. Development of novel diagnosti c methods that will enable early and accurate diagnosis of AD is of high importance. It is esti mated that any new interventi on against AD will have its greatest eff ect if applied early in the pathogenesis of the disease, when the brain is not that much aff ected. Anaylsis of the three proteins in the cerebrospinal fl uid (CSF) (Aβ42, total tau and phoshotau) gave the best results unti l now and showed that this test could be used for diff erenti al diagnosis of AD as well as for diagnosis of non-demented individuals and mildly cogniti vely impaired (MCI) individuals who will progress to AD in the future. Thus, the goal of the biomarker research is to identi fy changes that will diagnose AD in its earliest stage. We hope that diff erent aspects of reserach on AD will generate novel therapies and/or will help in preventi ng Alzheimer’s disease

Niemann Pick type C cells show cholesterol dependent decrease of APP expression at the cell surface and its increased processing through the β-secretase pathway

The link between cholesterol and Alzheimer’s disease has recently been revealed in Niemann Pick type C disease. We found that NPC1-/- cells show decreased expression of APP at the cell surface and increased processing of APP through the β-secretase pathway resulting in increased C99, sAPPβ and intracellular Aβ40 levels. This effect is dependent on increased cholesterol levels, since cholesterol depletion reversed cell surface APP expression and lowered Aβ/C99 levels in NPC1-/- cells to the levels observed in wt cells. Finding that overexpression of C99, a direct gamma-secretase substrate, does not lead to increased intracellular Aβ levels in NPC1-/- cells vs. CHOwt suggests that the effect on intracellular Aβ upon cholesterol accumulation in NPC1-/- cells is not due to increased APP cleavage by gamma-secretase. Our results indicate that cholesterol may modulate APP processing indirectly by modulating APP expression at the cell surface and, thus, its cleavage by β-secretase

Novel amino-β-lactam derivatives as potent cholesterol absorption inhibitors

Two new trans-(3R, 4R)-amino-β-lactam derivatives and their diastereoisomeric mixtures were synthesized as ezetimibe bioisosteres and tested in in vitro and in vivo experiments as novel β-lactam cholesterol absorption inhibitors. Both compounds exhibited low cytotoxicity in MDCKII, hNPC1L1/MDCKII, and HepG2 cell lines and potent inhibitory effect in hNPC1L1/MDCKII cells. In addition, these compounds markedly reduced cholesterol absorption in mice, resulting in reduced cholesterol concentrations in plasma, liver, and intestine. We determined the crystal structure of one amino-β-lactam derivative to establish unambiguously both the absolute and relative configuration at the new stereogenic centre C17, which was assigned to be S. The pKa values for both compounds are 9.35, implying that the amino-β-lactam derivatives and their diastereoisomeric mixtures are in form of ammonium salt in blood and the intestine. The IC50 value for the diastereoisomeric mixture is 60 μM. In vivo, it efficiently inhibited cholesterol absorption comparable to ezetimibe

Use of cerebrospinal fluid biomarker analysis for improving Alzheimer's disease diagnosis in a non-specialized setting

Low levels of amyloid-β42 (Aβ42) and high total-tau (t-tau) or phosphorylated-tau (p181-tau) levels in cerebrospinal fluid (CSF) were shown to be characteristic for Alzheimer’s disease (AD) patients and for mildly cognitively impaired (MCI) or non-demented individuals who will progress to AD. The goal of this study was to evaluate the benefit of CSF biomarker testing in a setting with no specialized dementia centers, in order to improve the accuracy of AD diagnosis and to identify individuals with incipient AD. Using ELISA assay we analyzed CSF Aβ42, t-tau and p181-tau levels among clinically diagnosed non-demented individuals, AD patients and individuals with uncertain dementia (n=36). CSF cut-off values of low Aβ42 (≤530 pg/mL) and high t-tau (≥350 pg/mL) or p181-tau (≥52 pg/mL) were used to identify individuals with AD/ MCI-CSF profile, regardless of clinical diagnosis. APOE genotyping was performed using PCR-RFLP method. In accord with previous studies we detected significantly decreased levels of CSF Aβ42 and increased tau and p181-tau levels in clinically diagnosed AD group vs. non-demented controls. CSF profiling identified individuals with a typical AD/MCI-CSF pattern in clinically referred non-demented group (9%) and among patients with uncertain dementia (41.7%). APOE ε4-allele was associated with the CSF biomarker changes typical for AD. This study shows that in a non-specialized setting CSF biomarker testing may be used as a screening tool for improving the accuracy of AD diagnosis and for predicting individuals with incipient Alzheimer’s disease who need to receive further clinical follow-up