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In addition to amyloid β and tau protein pathology, Alzheimer's disease (AD) is characterized by dysregulation of the inflammatory response. The main objective of this study was to find out how the concentrations of immune mediators (cytokines and chemokines) differ between AD, patients with mild cognitive impairment (MCI), and healthy controls (HC) in two different types of samples, cerebrospinal fluid (CSF) and plasma. We also wanted to determine the cytokine profile for each group. Using the Bio-Plex Pro Human Cytokine 48-Plex Screening Panel, we determined the levels of 35 cytokines in CSF and 47 in plasma samples. Twenty-nine AD, 35 MCI, and 40 HC CSF and 102 AD, 37 MCI, and 10 HC plasma samples were analyzed. In the plasma samples, only 4 cytokines differed significantly between the groups (CTACK, IL-12 (p40), IL-4, IL1Rα), whereas analysis of the CSF samples revealed significantly different levels of 15 immune mediators (IL-1β, IL-1α, IL-3, IL-4, IL-7, IL-16, IL-17A, IL-18, IFN-γ, GRO-α, MIP-1β, CTACK, TNF-α, IL-2Rα, IP-10). Most of the mediators whose levels differed significantly were increased in the AD group ; only IP-10 had the highest levels in the MCI group. CSF analysis showed that the AD group was characterized by a pro-inflammatory profile and a higher rate of an adaptive immune response. Higher levels of predominantly pro-inflammatory cytokines (IL-1β, IL-18, MIG, EOTAXIN, MIP-1α, MIP-1β, TNF-β) were associated with higher levels of cognitive deficits. This study has shown that measurement of immune mediators in CSF, but not in plasma, may be a good strategy to track the immune response during disease progression and could be a promising tool for evaluating potential future immune and anti-inflammatory interventions.

Emerging experimental evidence suggests that the spread of tau pathology in the brain in human neurodegenerative disorders reflects the propagation of misfolded tau along neuroanatomically connected brain regions, with the first changes seen in the brainstem and entorhinal cortex spreading trans-synaptically along specific pathways to other brain regions. Most of the in vivo spreading of tau has been shown in transgenic mouse models that overexpress mutated or wild-type human tau. The use of genetic models of familial Alzheimer's disease (AD) may not represent the complete picture of the disease in humans. Therefore, other types of animal models relevant to the sporadic form, which represents over 95 % of all AD cases, must be developed. In the study, we aimed to characterize possible pathological changes and the propagation of different forms of tau species in non-transgenic 3-4 months-old wild-type Wistar rats after a single unilateral injection of human tau oligomers and tau fibrils into the medial entorhinal cortex (mEC). We determined whether tau fibrils and tau oligomers would induce neurofibrillary changes and propagate like AD and whether this tau-related pathology would correlate with cognitive impairment. We injected human tau fibrils and tau oligomers stereotaxically into the mEC and examined the distribution of tau-related changes at different time points (4, 8, and 11 months post-injection) using antibodies AT8 for early phosphorylation and MC1 for aberrant conformation of tau. Colocalization was performed with the synaptophysin antibody to analyze whether inoculated tau proteins enter synapses and affect their decay. We observed that tau oligomers and tau fibrils exhibit different effects in terms of the ability to propagate tau-related changes. Both variants of inoculated tau proteins rapidly spread via anterograde axonal transport to the hippocampus and various parts of the neocortex, including the primary motor and somatosensory areas. Rats inoculated with human tau fibrils showed, as early as 4 months after inoculation, a spread of phosphorylated tau protein at the AT8 epitopes throughout the brain and faster propagation of neurofibrillary changes than with human tau oligomers. The severity of tau changes after inoculation of human tau oligomers and tau fibrils correlated with impairments in spatial working memory and cognition, as measured by the T-maze, novel object recognition, and object location tests. We concluded that this non-transgenic rat model of tauopathy, especially when using human tau fibrils, demonstrates rapidly developing pathologic alterations in neurons and synapses together with cognitive and behavioral changes through the anterograde and retrograde spreading of neurofibrillary degeneration. Therefore, it represents a promising novel model for experimental studies of primary and secondary tauopathies, especially AD.

People with specific TREM2 gene variants are more prone to develop Alzheimer's disease (AD). The TREM2 receptor regulates the number of myeloid cells, phagocytosis, and the inflammatory response via interacting with apolipoproteins and amyloid. Higher TREM2 expression has been found to protect against AD. When TREM2 activity increases, the activity of genes involved in the activation of microglia cells decreases. This can improve the efficiency of phagocytosis. When TREM2 is highly expressed and the inflammasome is activated, the results are not always congruent. Therefore, this study aimed to discover how sTREM2 levels in CSF and plasma samples relate to other indices of AD pathology. We examined 98 AD plasma samples, 35 plasma samples of subjects with mild cognitive impairment (MCI), 11 healthy controls (HC) plasma samples, as well as 155 AD CSF samples, 90 MCI CSF samples, and 50 HC CSF samples. CSF sTREM2 levels were higher in the AD group than in the MCI and HC groups, in contrast to plasma sTREM2. This shows that CSF sTREM2 levels could be used to distinguish between healthy and AD patients. CSF sTREM2 levels were significantly correlated with neurofibrillary changes, cognitive decline, and inflammasome activity in AD patients. While our findings are consistent with previous research, future studies will need to include more patients and employ standardized methodological approaches to add CSF sTREM2 to the list of biomarkers for AD.

The neuropathologic hallmarks of Alzheimer's disease (AD) include the following key features: amyloid plaques, neurofibrillary tangles (NFTs ; composed of abnormally phosphorylated tau proteins), glial responses, and synaptic and neuronal loss. Across the AD continuum, Aβ plaques are thought to be the earliest pathological changes that are followed by tau NFTs accumulation, inflammation, synaptic degeneration, and neuronal loss. Neurodegeneration and synapse loss are the best correlates of clinical symptoms. Around 20% of the peptides and proteins in CSF are derived from the brain. The concentration of brain-derived peptides and proteins is the highest in the ventricles and decreases as it flows to the subarachnoid spaces. Blood testing is less invasive than CSF testing and can easily be performed in a variety of settings and at repeated intervals. Blood-based biomarkers, reflecting proteins originating from the brain, are typically present at low concentrations because of dilution in the volume of blood ; biomarkers present in the blood may also undergo additional proteolytic cleavage by proteases in plasma. CSF total tau protein (t-tau) measures the intensity of neurodegeneration in AD but is not a disease-specific marker. T-tau is increased in the CSF of patients with AD dementia and some other neurological conditions whereas phosphorylated tau (p-tau) in CSF measures the amount of tau that is phosphorylated, a variant of tau found in NFTs. In AD, p-tau in CSF is increased. On the other hand, CSF amyloid (Aβ42) is decreased in AD and is thought to reflect the aggregation and deposition of the protein in the brain. Neuronal/astrocyte-derived exosomes in AD have increased content of Aβ42, p-tau181, p-tau396, t-tau, BACE-1, APP, complement effector proteins, IL1β, IL-6, TNF-α, cathepsin D, LAMP-1, ubiquitinylated proteins, AACT, RAS suppressor protein, GP1B, whereas the content of neurogranin, neuromodulin, SNAP-25, synaptotagmin, synaptopodin, synaptophysin, complement regulatory proteins, neurotrophic and growth factors is decreased. Plasma brain-derived exosomes, either neuronal or astrocytic, have multiple potential roles. Harmful actions include the spreading of amyloid and tau pathological changes, mediating neuron-to-neuron propagation of both amyloid and tau oligomers, and induction of neuronal apoptotic pathways. Beneficial actions include binding of extracellular Aβ42 and promoting its degradation, neutralizing Aβ-induced disruption in synaptic plasticity, carrying nucleic acids with gene expression regulating abilities, and serving as therapeutic vehicles of drug delivery for AD. The current inconsistency between the extraction of exosomes and detection procedures of exosome cargos is one of the main limitations of exosome-related studies.

Introduction The main goal of this study was to evaluate the effect of nusinersen treatment in patients with spinal muscular atrophy (SMA) on cerebrospinal fluid (CSF) S100 calcium-binding protein B (S100B) levels. We were also interested in determining whether CSF S100B protein is associated with genetic biomarkers of SMA, scores on the Hammersmith Functional Motor Scale Expanded (HFMSE), and The Children’s Hospital of Philadelphia Infant Test of Neuromuscular Disorders (CHOP-INTEND) scales for the assessment of motor functions in SMA patients, as well as type and duration of SMA. Materials and Methods The study involved Thirty SMA patients at the University Hospital Centre Zagreb. Before administering nusinersen, CSF samples were obtained from patients via lumbar puncture. Using Enzyme-Linked Immunosorbent Assay (ELISA), the CSF S100B concentration was measured. We used the CHOP-INTEND and the HFMSE instruments to evaluate motor functions in SMA patients. The Multiplex Ligation-dependent Probe Amplification (MLPA) technique was utilized for all genetic analyses. SPSS version 19.0.1 (SPSS, Chicago, Illinois, United States) was used for statistical data analysis. Due to the non-normal distribution of the data, non-parametric tests were utilized. Results The levels of CSF S100B did not change significantly in SMA patients treated with nusinersen. In addition, there was no association between S100B levels and scores on the HFMSE and CHOP-INTEND scales or genetic biomarkers of SMA (the number of copies of the NAIP gene and the number of copies of the 7th exon of the SMN2 gene). The S100B levels of patients with distinct types of SMA were identical. However, S100B levels were positively correlated with disease duration. Discussion/Conclusion S100B protein did not exhibit the characteristics of an informative biological marker for the therapeutic response of patients with SMA during nusinersen therapy, as nusinersen administration had no effect on S100B levels. Also, no association between S100B protein and SMA genetic biomarkers was established. Nonetheless, S100B values were positively correlated with disease duration.

Introduction: Alzheimer's disease (AD) and mild cognitive impairment (MCI) are characterized by different phases of cognitive decline. In AD, there is a progressive impairment of acquired cognitive abilities while subjects with MCI show less severe cognitive disturbances. Cognitive dysfunction develops as a result of the complex interactions between multiple genetic, epigenetic, developmental, and environmental factors. Among many genes involved in cognition is the gene coding for catechol- O-methyltransferase (COMT), the enzyme responsible for the degradation of dopamine, resulting in the modulation of dopaminergic function. Therefore, COMT genetic variants were studied in various dementias characterized by cognitive loss. The aim of the study was to evaluate the possible association between COMT rs6269 and COMT rs4680 polymorphisms and cognitive decline in subjects with AD and MCI. Methods: Cognitive deterioration was assessed with the Mini-Mental State Examination (MMSE) and the Clock Drawing test (CDT) scores in 193 patients with AD and 269 subjects with MCI. COMT rs6269 and COMT rs4680 (Val158Met) were genotyped using the real-time PCR. Multiple linear regressions and Kruskal Wallis ANOVA were used to detect the association of the COMT rs6269 or COMT rs4680 genotypes with cognitive decline. Results: Multiple linear regression showed that COMT rs6269 was significantly associated with MMSE and CDT scores and these effects were affected by diagnosis and COMT rs6269 genotypes and age. In contrast, multiple linear regression revealed that COMT rs4680 was not significantly associated with MMSE or CDT scores, and the only significant effects were found for age and diagnosis. To further evaluate the effect of COMT polymorphisms on cognition, all subjects were subdivided into AA, GA, or GG genotype carriers of the COMT rs6269 or COMT rs4680, respectively, and according to MMSE or CDT scores. Carriers of the GG genotype of the COMT rs6269 had significantly (p=0.007) lower CDT scores than AA carriers, while other genotype groups did not differ significantly according to the CDT or MMSE scores. Conclusion: Although COMT rs4680 (Val158Met) was reported to be related to cognitive loss in various neuropsychiatric disorders, present results revealed a significant association between the other COMT polymorphism, rs6269, with cognitive deterioration in dementia.

Prema jednom od mnogih različitih i neusklađenih pogleda na fenomen svijesti, ključna razlika između stanja mozga u kojima smo svjesni i onih u kojima nismo jest u tome što sva svjesna stanja uključuju elemente neke vrste pamćenja. Anoetička (neznalačka) svijest ne zna ništa o prošlosti i budućnosti, nije dostupna introspekciji, odnosno meta-reprezentaciji, a temelji se na proceduralnom pamćenju. Noetička (znalačka) svijest temelji se na semantičkom pamćenju, tj. sadrži činjenice o općim zakonima, pravilima i konceptima, ne zahtjeva ekplicitnu samosvjesnost i ne omogućuje mentalno putovanje kroz vrijeme. Autonoetička svijest je najviši oblik svijesti o samome sebi u sadašnjem trenutku i u odnosu na vlastitu prošlost i budućnost. Njezino je uporište u epizodičkom pamćenju, te nam jedino ona daje osjećaj kontinuiteta jastva, ali također i mogućnost mentalnog putovanja u vlastitu prošlost i budućnost. Zbog navedene povezanosti pamćenja i svijesti smatra se da bi nam bolje razumijevanje neuronskih mreža koje posreduju pojedine vrste pamćenja mogle omogućiti i bolji uvid u različite vrste svijesti.

U predavanju je najprije dan kratki povijesni pregled glavnih spoznaja o otkrićima povezanim s razumijevanjem svijesti (René Descartes, Hans Berger, Frédéric Bremer, Giuseppe Moruzzi i Horace Magoun, Alf Brodal, Mircea Steriade, Rodolfo Llinas, Edward Jones, Marcus Raichle, Michael Greicius, Randy Buckner). Zatim su opisane dvije glavne dimenzije svijesti (budnost i svjesnost), njihov predmnijevani biološki aparat (retikulska formacija i pridružene jezgre te ascendentni retikulski aktivacijski sustav, opće i specifične talamičke jezgre, talamokortikalne oscilacije, kortikokortikalne mreže i čvorišta) i glavni poremećaji. Na kraju su još opisani neki miljokazi u razvitku svijesti čovjeka, dan detaljniji opis temeljna mreža (default network), sposobnost mentalnog putovanja kroz vrijeme (mental time travel) i teorija uma (theory of mind). Navedene teme je predavač nastojao staviti u kontekst i objasniti važnost njihovog razumijevanja u svakodnevnom radu pedagoga.

Kako bi preživjeli i stvorili bilo koji oblik društvene organizacije, moramo razumjeti djelovanje i namjere drugih osoba. Učenje oponašanjem temelj je kulture čovjeka, a djeca imitiraju odrasle u puno većoj mjeri nego drugi čovjekoliki majmuni. Stoga i podučavanje treba biti prvenstveno ono putem vlastitog primjera (npr. ako želite da dijete ne puši, onda nećete pred njim pušiti i govoriti mu da je to štetno). Iako odavno znamo kako djeca većinom nesvjesno usvajaju aktivnosti, navike, vokabular i ideje članova zajednice u kojoj žive, danas znamo da je većina takvih aktivnosti posredovana sustavima „zrcalnih“ neurona u moždanoj kori čeonog i tjemenog režnja koji se aktiviraju već samim gledanjem određenih aktivnosti drugih osoba (izreka „što majmun vidi, to majmun radi” još više vrijedi i za ponašanje čovjeka) ; takva aktivnost se npr. može snimiti u Brocinom motoričkom području za govor, dok dijete gleda druge osobe kako govore. Na temelju tih i drugih rezultata smatra se da je Brocino motoričko područje za govor nastalo i lateraliziralo se povećanjem susjednog područja neurona specijaliziranih za izvođenje pokreta (gestikulaciju) dominantne (desne) ruke. Djeca s poremećajima iz autističnog spektra, što danas uključuje i djecu s Aspergerovim sindromom, ne mogu „čitati” namjere drugih osoba ili ih razumiju pogrešno, imaju odstupanja u društvenoj komunikaciji i interakciji te atipičnosti u obilježjima općeg ponašanja i interesa. Djeca najbolje uče kad su uključena u aktivnosti za koje misle da su korisne u svakodnevnom životu, odnosno da su važne u društvenom/kulturnom kontekstu. Stoga im treba što češće ukazivati na korist naučenog sadržaja, a što više aktivnosti staviti u društveni/kulturni kontekst, npr.: - vježbanje govornih i komunikacijskih vještina kroz debate kakve se mogu vidjeti na televiziji ; - vježbanje sposobnosti pisanja i izražavanja kroz npr. izdavanje školskog lista ; - učenje kroz kontakte sa stručnjacima i znanstvenicima u lokalnoj zajednici ; - učenici mogu doći i na njihovo radno mjesto npr. tijekom aktivnosti u Tjednu mozga. Nova znanja se bolje pamte ako se nadovezuju na prethodno usvojena ; još je od Aristotela poznata činjenica da sposobnost učenja novoga zavisi od prethodnog znanja, jer je nove činjenice potrebno asocirati tj. povezati s onima koje su otprije poznate i stabilne u vlastitom mentalnom okruženju. Učenje je uspješnije ako učitelj pažljivo analizira prethodno znanje učenika o nekom sadržaju i upotrijebi ga kao polaznu točku za objašnjavanje novoga („building blocks of knowledge”). Podučavanje treba započeti od većih, općepoznatih i konkretnih činjenica, a zatim nadovezivati sitnije, manje poznate i apstraktne. Što je više različitih načina usvajanja i obrade određenog sadržaja, veća je i vjerojatnost njegovog kasnijeg prisjećanja (sinestezija) ; najmanje trećinu vremena treba rezervirati za ponavljanje i provježbavanje. Od najranije dobi djeca razvijaju strategije da bi si pomogla riješiti probleme na koje nailaze (tzv. preferirani kognitivni stil), npr. složeni prostorni problem čitanja karte može se riješiti korištenjem vidno-prostornih (smjer i mjesto na koje treba doći se kodira prostorno) ili verbalnih sposobnosti (prostorna informacija s kodira u instrukcije o skretanju korak po korak) ; većinom djevojčice preferiraju verbalni kognitivni stil i njime će riješiti taj zadatak verbalno iako je taj postupak u ovom slučaju manje učinkovit. Učitelj pomaže izravno (eksplicitno) ukazujući djetetu što je važno ili neizravno pomažu mu da samo dođe do odgovora ; u zavisnosti od starosti i sposobnosti učenika, u idealnom bi slučaju učitelji trebali postepeno smanjivati svoj utjecaj i pružanje podrške u rješavanju problema, tako da učenici preuzimaju sve veću odgovornost za vlastito učenje i napredovanje. Pritom djecu ne treba pohvaljivati i nagrađivati zato što su sama po sebi jako „pametna“ i „inteligentna“, pa su brzo i bez napora riješila određene zadatke i probleme, već ih treba pohvaljivati za učinjeni trud! Nekoliko je istraživanja provedenih još 2004. godine pokazalo da su ovakva djeca s vremenom sve više zaostajala jer su se sve manje trudila i hvatala ukoštac sa sve težim gradivom, te „odabirala“ samo ona područja i zadatke koji su im išli bolje, da bi na kraju ispitivanog razdoblja bila u značajnom zaostatku u odnosu na skupinu djece koja su pohvaljivana za napor koji su uložili da bi savladali određeni sadržaj. iako treba težiti razumijevanju, a ne pukom memoriranju, ne smije se zanemariti važnost poznavanja činjenica neophodnih za rješavanje problema. Površno zapamćene informacije lako se zaboravljaju ; nasuprot tome, kada se nešto dobro razumije, teže se zaboravlja i može se bez poteškoća koristiti u raznim situacijama. Stupanj lakoće usvajanja i upamćivanja novih činjenica veći je što je dijete mlađe, pa nije iznenađujuće da npr. predškolci znaju više pokemona nego stvarnih životinja. Dakle, same činjenice ne predstavljaju problem, već njihova zanimljivost, te logičnost (sustavnost) usvajanja. Jedna od najboljih predskazujućih varijabli za budući uspjeh djeteta je njegova sposobnost nositi se s negativnim emocijama te je li ih u stanju prenijeti i podijeliti s osobama u koje ima povjerenja. Učitelj treba pozitivno (nagrađivanjem, a ne kažnjavanjem) poticati učenike na učenje, poticati ih na suradnju s drugim učenicima, te da im zadavati smislene zadatke putem autentičnih materijala. Unutarnji (interni) čimbenici učenja (npr. inteligencija) su individualni i visoko nasljedni, ali se nikad ne smije zaboraviti da je plastičnost dječjeg mozga ogromna i da su ovi čimbenici u stalnoj i neprekidnoj interakciji s okolinom, te da je stoga kod svakog učenika daljnji napredak uvijek moguć. Dopaminske mezolimbičke i mezokortikalne projekcije čine kostur univerzalnog sustava nagrade. U slučaju neispunjenja nekih zadanih ciljeva aktivaciju ovog sustava čovjek pokušava postići na neki drugi, obično predvidljiviji i lakše dostupan način ; npr. neispunjenje školskih ili radnih zadataka ili neki drugi neuspjeh često se „nadoknađuje“ prekomjernim jedenjem (displacement behavior) da bi se ipak postigao planirani stupanj nagrade/ugode, a koji je zbog nekog razloga izostao. Inteligentnija djeca u istim uvjetima brže dolaze do točnih odgovora, te mogu dulje odgađati ugodu (čine bolje dugoročne izbore). O svemu tome više u knjizi "Uvod u neuroznanost emocija i osjećaja", Zagreb: Naklada Ljevak (2020).

Introduction The purpose of this study was to examine the effect of nusinersen treatment on the concentration of total tau (t-tau) protein in cerebrospinal fluid (CSF) of patients with spinal muscular atrophy (SMA). SMA is an autosomal recessive disorder characterized by degeneration of the spinal cord anterior horn motoneurons, which is caused by homozygous deletion or mutation of the survival motor neuron 1 (SMN 1) gene. We also analyzed the association between CSF t-tau and genetic biomarkers of SMA (the number of copies of the 7th exon of the SMN2 gene and the number of copies of the NAIP gene), scores on measures for assessing motor functions, duration and type of SMA. Materials and Methods 30 patients with SMA types 1, 2, and 3 who were treated at the University Hospital Centre in Zagreb participated in the study. T-tau concentration in CSF was determined using Enzyme-Linked Immunosorbent Assay (ELISA) from lumbar puncture samples of CSF. Their motor function was measured using the Children's Hospital of Philadelphia Infant Test of Neuromuscular Disorders (CHOP-INTEND) and the Hammersmith Functional Motor Scale Expanded (HFMSE). Using the Multiplex ligation-dependent probe amplification technique (MLPA), genetic analyses were conducted. SPSS version 19.0.1 was utilized for statistical data analysis (SPSS, Chicago, IL, USA). Results After treatment with nusinersen, CSF t-tau levels decreased significantly. There were no statistically significant differences in CSF t-tau levels between SMA patients with various genetic biomarkers. In addition, there was no correlation between t-tau levels and scores on the COOP-INTEND and HFMSE scales. There was no association between CSF t-tau and SMA duration or subtype. Discussion/Conclusion CSF t-tau protein proved to be a prognostic and theragnostic biological marker of a successful response in patients with SMA, as its average values decreased in a statistically significant manner following administration of nusinersen. However, t-tau did not correlate with genetic biomarkers of SMA, motor function assessment scale scores, disease duration, or disease type.

The tauopathy of Alzheimer’s disease (AD) is first observed in the brainstem and entorhinal cortex, spreading trans-synaptically along specific pathways to other brain regions with recognizable patterns. Tau propagation occurs retrogradely and anterogradely (trans-synaptically) along a given pathway and through exosomes and microglial cells. Some aspects of in vivo tau spreading have been replicated in transgenic mice models expressing a mutated human MAPT (tau) gene and in wild-type mice. In this study, we aimed to characterize the propagation of different forms of tau species in non-transgenic 3–4 months old wild-type rats after a single unilateral injection of human tau oligomers and tau fibrils into the medial entorhinal cortex (mEC). We determined whether different variants of the inoculated human tau protein, tau fibrils, and tau oligomers, would induce similar neurofibrillary changes and propagate in an AD-related pattern, and how tau- related pathological changes would correlate with presumed cognitive impairment. We injected human tau fibrils and tau oligomers stereotaxically into the mEC and examined the distribution of tau- related changes at 3 days and 4, 8, and 11 months post-injection using antibodies AT8 and MC1, which reveal early phosphorylation and aberrant conformation of tau, respectively, HT7, anti- synaptophysin, and the Gallyas silver staining method. Human tau oligomers and tau fibrils exhibited some similarities and some differences in their ability to seed and propagate tau-related changes. Both human tau fibrils and tau oligomers rapidly propagated from the mEC anterogradely into the hippocampus and various parts of the neocortex. However, using a human tau-specific HT7 antibody, 3 days post-injection we found inoculated human tau oligomers in the red nucleus, primary motor, and primary somatosensory cortex, a finding not seen in animals inoculated with human tau fibrils. In animals inoculated with human tau fibrils, 3 days post-injection the HT7 antibody showed fibrils in the pontine reticular nucleus, a finding explained only by uptake of human tau fibrils by incoming presynaptic fibers to the mEC and retrograde transport of inoculated human tau fibrils to the brainstem. Rats inoculated with human tau fibrils showed as early as 4 months after inoculation a spread of phosphorylated tau protein at the AT8 epitopes throughout the brain, dramatically faster propagation of neurofibrillary changes than with human tau oligomers. The overall severity of tau protein changes 4, 8, and 11 months after inoculation of human tau oligomers and tau fibrils correlated well with spatial working memory and cognition impairments, as measured by the T-maze spontaneous alternation, novel object recognition, and object location tests. We concluded that this non-trangenic rat model of tauopathy, especially when using human tau fibrils, demonstrates rapidly developing pathologic alterations in neurons, synapses, and identifiable pathways together with cognitive and behavioral changes, through the anterograde and retrograde spreading of neurofibrillary degeneration. Therefore, it represents a promising model for future experimental studies of primary and secondary tauopathies, especially AD.

The role of metals in the pathogenesis of Alzheimer’s disease (AD) is still debated. Although previous research has linked changes in essential metal homeostasis and exposure to environmental heavy metals to the pathogenesis of AD, more research is needed to determine the relationship between metals and AD. In this review, we included human studies that (1) compared the metal concentrations between AD patients and healthy controls, (2) correlated concentrations of AD cerebrospinal fluid (CSF) biomarkers with metal concentrations, and (3) used Mendelian randomization (MR) to assess the potential metal contributions to AD risk. Although many studies have examined various metals in dementia patients, understanding the dynamics of metals in these patients remains difficult due to considerable inconsistencies among the results of individual studies. The most consistent findings were for Zn and Cu, with most studies observing a decrease in Zn levels and an increase in Cu levels in AD patients. However, several studies found no such relation. Because few studies have compared metal levels with biomarker levels in the CSF of AD patients, more research of this type is required. Given that MR is revolutionizing epidemiologic research, additional MR studies that include participants from diverse ethnic backgrounds to assess the causal relationship between metals and AD risk are critical.

• Pet je glavnih skupina eksperimentalnih modela transgeneracijske traume: 1. Modeli odvajanja od majke. Mladunci eksperimentalnih životinja odvajaju se od svojih majki na određeno vrijeme tijekom ranog razvoja. Takvo iskustvo izaziva dugotrajne promjene u ponašanju i fiziološke promjene u potomstvu, uključujući promjene u reakcijama na stres, ponašanja nalik anksioznosti i oštećenje društvenih interakcija. Fizičko i emocionalno zanemarivanje osnovnih potreba djeteta ima enorman traumatski učinak na dijete, a neke od promjena uočene su i u više generacija što ukazuje na transgeneracijski prijenos učinaka traume iz ranog života. Isti ili sličan učinak odvajanju ima i nedostatna majčinska skrb. Odvajanje od majke tijekom prvog tjedna života izaziva hipermetilaciju promotora gena NR3C1 za glukokortikoidni receptor u hipokampusu miša), a ovakav traumatski stres traje, zajedno s abnormalnim ponašanjem, doživotno i prenosi se trangeneracijski (Creasey N. et al., Dev. Psychopathol., 2023). Pokazano je da je status metilacije NR3C1 gena za glukokortikoidni receptor adolescenata starih 10-17 godina bio pod utjecajem majčinog iskustva nasilja od intimnog partnera tijekom trudnoće (Radtke K. M. et al., Transl. Psychiatry, 2011). Na uzorku od 93.391 osobe pokazalo se da su djevojčice evakuirane tijekom Drugog svjetskog rata iz Finske u švedske udomiteljske obitelji imale kao odrasle osobe dvostruko veći rizik psihijatrijske hospitalizacije zbog poremećaja raspoloženja u odnosu na njihove sestre koje nisu bile evakuirane (Santavirta T. et al., JAMA Psychiatry, 2018). Primjena vanjskih stresora u kombinaciji s odvajanjem potomaka od majke smatra se jednim od najboljih životinjskih modela za proučavanje transgeneracijskog nasljeđivanja traumatskog stresa budući da ponovljivo utječe na nekoliko uzastopnih generacija. Takav model koristi kombinaciju svakodnevnog nepredvidivog (nasumičnog) odvajanja mladunaca miševa (F1) od njihove majke (F0), s istodobnim nepredvidivim (nasumičnim) izlaganjem majke stresu (F0) tijekom odvajanja (model of unpredictable maternal separation and unpredictable maternal stress, MSUS). Ova ponavljajuća i nepredvidiva traumatska iskustva tijekom postnatalnog razdoblja od prvog do četrnaestog dana mijenjaju ponašanje potomstva u tri generacije. Pretpostavlja se da F2 i F3 generacija miševa koje pokazuju ponašanja slična depresiji nisu posljedica promjena u majčinskoj skrbi budući da navedeno ponašanje ostaje i nakon udomljavanja. Također, F2 i F3 generacija miševa pokazuje manji otpor u istraživanju nepoznate okoline i sveukupno rizičnije ponašanje (Franklin T. B. et al., Biol. Psychiatry, 2010 ; Gapp K. et al., Nat. Neurosci. 2014). 2. Modeli uvjetovanja straha. Eksperimentalne životinje, često glodavci, izlažu se traumatskom događaju poput strujnog udara na podlogu kaveza ili izloženost predatoru (Unconditioned Stimulus, US), spregnuti u vremenu s određenim neutralnim objektom ili kontekstom (Conditioned Stimulus, CS). Životinje nakon toga pokazuju reakciju straha kad su izložene CS-u. Uvjetovanje strahom može dovesti do transgeneracijskih učinaka, pri čemu potomci pokazuju pojačane reakcije i strah u neopasnim situacijama te čak i u odsutnosti izravne izloženosti traumatskom događaju. Kad se miševi nauče bojati mirisa, npr. u jednom pokusu mirisa urina lisice, i njihovi potomci i sljedeća generacija rađaju se bojeći ga se. Gen za njušni receptor aktiviran tim mirisom specifično je demetiliran u zametnoj liniji, pa i ekspresija toga receptora u potomaka dovodi do puno bržeg uvjetovanja straha od navedenog mirisa (Szyf M., Nature, 2014). 3. Modeli kroničnog stresa: eksp. životinje se izlažu produljenim stresorima tijekom duljeg razdoblja (društvena izolacija, fizičko ograničavanje kretanja, izloženost nepredvidivim uzrocima stresa ne koje životinja ne može utjecati). Kronični stres dovodi do promjena u ponašanju povezanih s anksioznosti, depresijom i kognitivnim oštećenjima. U nekim istraživanjima su dokumentirani transgeneracijski učinci kroničnog stresa, s promjenjenim reakcijama na stres u više generacija. 4. Modeli društvenog poraza: U modelima društvenog poraza, životinje se izlažu ponovljenim epizodama agresije i poraza od strane dominantnih srodnika. Takav kronični društveni stresor izaziva niz fizioloških promjena i promjena u ponašanju kod poraženih životinja, uključujući povećanu anksioznost, socijalno povlačenje i promijenjenu regulaciju HHO i lučenje endokrinih žlijezda. Istraživanja ukazuju da i potomci socijalno poraženih životinja često pokazuju slične promjene, što ukazuje transgeneracijski prijenos. 5. modeli prenatalnog stresa: modeli prenatalnog stresa uključuju izlaganje gravidnih životinja stresorima tijekom gestacije: fizičkom stresu, ograničavanju kretanja, izlaganju buci ili davanju tvari koje izazivaju stres (npr. kortikosterona). Dokazano je da prenatalni stres utječe na potomstva potomstvo te izaziva neurorazvojne promjene u migraciji neurona, sinaptogenezi, mijelinizaciji, a kasnije abnormalnosti ponašanja, povećanu osjetljivosti na stres i anksiozne poremećaje. Sve navedene promjene uočene su i u nekoliko generacija. Epigenetička regulacija odvija se i na transkripcijskoj i post-transkripcijskoj razini. Proces starenja svih stanica i tkiva uključuje rasprostranjene epigenetičke promjene. Gotovo sve neurodegenerativne bolesti, napose Alzheimeova bolest, povezane su s poremećenom epigenetičkom regulacijom. Reverzibilna narav epigenetičkih promjena obećavajući je terapijski cilj, a za bolje razumijevanje epigenetičkih procesa još uvijek su najveća prepreka metodološki problemi - skupoća opreme i nestandardiziranost postupaka. Tijekom starenja dolazi do sveukupnog smanjenja metilacije DNA, iako su neki pojedinačni geni hipermetilirani (npr. promotori BDNF i CREB gena). Sveukupna razina sniženja može se upotrebljavati za određivanje starosti (Horvathov epigenetički sat, Horvath S. Gen. Biol., 2013). Budući da pluripotentne stanice uspijevaju izbjeći promjene metilacije DNA povezane sa starenjem, reprogramiranje starih stanica može ih regenerirati (epigenetička rejuvenacija). Inicijalno je ireverzibilni inhibitor DNA metil-transferaze 1 (DNMT1) 5-azacitidin odobren od FDA 19. svibnja 2004. za mijelodisplastičke sindrome (kojima je uzrok hipermetilacija tumor-supresorskih gena), a zatim su mu proširene indikacije 2009, 2012 i 2014 za liječenje različitih zloćudnih tumora, uključujući akutnu mijeloičnu leukemiju. Time je otvoren put za istraživanje i registraciju i drugih spojeva koji djeluju na epigenetičke mehanizme u drugim bolestima i stanjima, npr. vjeruje se da bi se sprječavanjem hipometilacije APP gena moglo spriječiti povećano stvaranje amiloida  u prevenciji ne samo Alzheimerove bolesti nego možda i samog procesa starenja. U stadiju mladih spermatogonija histoni su hiperacetilirani, ali s vremenom se i ubikvitiniraju, a histone zamjenjuju protamini 1 i 2 u omjeru 1:1 ; takvo nuklearno zbijanje DNA karakteristika je zrelih spermija. Oko 5–15% histona otporno je na zamjenu protaminima i zadržava se i u zrelih spermija ; zadržani histoni nalaze se na genima važnima za razvoj, nekim poznatim utisnutim (imprinted) genima i lokusima mikroRNA gena, a sadrže i epigenetičke modifikacije H3K4 metilaciju (H3K4me3) i H3K27 metilaciju (H3K27me3). Mikro-RNA nastaju od svojih vlastitih gena (60%) ili od introna (oko 40% svih miRNA). U većini slučajeva su orijentirane u suprotnom smjeru od susjednih gena pa se transkribiraju kao neovisne jedinice, ali u nekim slučajevima se transkribiraju s genom domaćinom i funkcija im je vjerojatno povezana. Prva miRNA otkrivena je 1993. godine, a do danas ih je opisano oko 3000 (većina u mozgu). Skoro svaka miRNA može imati i po više stotina ciljnih mRNA. Oko 10% svih miRNA su male interferirajuće RNA (siRNA) koje se vežu za molekule glasničke RNA (mRNA) i sprječavaju njihovo prevođenje u proteine ili potiču njihovu razgradnju putem RISC kompleksa (RNA-induced silencing complex). S obzirom na činjenicu da se u razdoblju ranog embrijskog razvitka 5-7 dana u stadiju blastociste, kad je zametak velik samo 70-100 stanica, vrši opsežna demetilacija cijeloga genoma da bi se aktivirali geni koji daju stanicama svojstvo pluripotentnosti, zaključeno je da još uvijek nije jasno na koji se način održava prijenos epigenetičkih promjena u sljedeću/sljedeće generacije.

Background: The primary histological characteristic of Alzheimer's disease is the presence of neurofibrillary tangles, which are large aggregates of tau protein. Aging is the primary risk factor for the development of Alzheimer's disease, however, the underlying causes of tau protein aggregation and toxicity are unclear. Aims: Here we investigated tau aggregation and toxicity under the conditions of compromised protein homeostasis. Methods: We used heterologous expression of human tau protein in the unicellular eukaryote yeast Saccharomyces cerevisiae with evolutionarily conserved protein quality control pathways and examined tau-dependent toxicity and aggregation using growth assays, fluorescence microscopy, and a split luciferase-based reporter NanoBiT. Results: Tau protein expressed in yeast under mild proteotoxic stress, or in mutants with impaired pathways for proteotoxic stress response, did not lead to synthetic toxicity or the formation of obvious aggregates. Chronologically old cells also did not develop observable tau aggregates. Our examination of tau oligomerization in living cells using NanoBiT reporter suggests that tau does not form significant levels of oligomers under basal conditions or under mild proteotoxic stress. Conclusion: Together our data suggest that human tau protein does not represent a major burden to the protein quality control system in yeast cells.