Petur Henry Petersen

• Professor Neuroscience
• University of Iceland

Background. Mild cognitive change is common with increasing age and may generate concern. Two stages of mild cognitive changes have been defined; subjective cognitive impairment and mild cognitive impairment (MCI), which is confirmed through cognitive testing. Individuals referred to the Landspítali memory clinic and diagnosed with mild cognitive i...

The microphthalmia-associated transcription factor (MITF) is a master transcription factor in melanocytes and plays equally important roles in mast cells. It is required for the generation, differentiation, and function of these cell types in vertebrates. Mitf is also expressed in the projection neurons of the olfactory bulb (OB), the mitral and tu...

Age-related decline occurs in most brain structures and sensory systems. An illustrative case is olfaction, where the olfactory bulb (OB) undergoes deterioration with age, resulting in reduced olfactory ability. Decline in olfaction is also associated with early symptoms of neurodegenerative diseases including Alzheimer’s disease (AD) and Parkinson...

Mast cells (MCs) are located in the meninges of the central nervous system (CNS), where they play key roles in the immune response. MC-deficient mice are advantageous in delineating the role of MCs in the immune response in vivo. In this study, we illustrate that a mutation in microphthalmia-associated transcription factor (Mitf) affects meningeal...

Background Cholinergic drugs are the most commonly used drugs for the treatment of Alzheimer’s disease (AD). Therefore, a better understanding of the cholinergic system and its relation to both AD-related biomarkers and cognitive functions is of high importance. Objectives To evaluate the relationships of cerebrospinal fluid (CSF) cholinergic enzy...

Objective To test if patients recovering from COVID-19 are at increased risk of mental morbidities and to what extent such risk is exacerbated by illness severity. Design Population-based cross-sectional study. Setting Iceland. Participants A total of 22 861 individuals were recruited through invitations to existing nationwide cohorts and a soci...

Background Understanding how dysregulation in lipid metabolism relates to the severity of Alzheimer‘s disease (AD) pathology might be critical in developing effective treatments. Objective To identify lipid species in cerebrospinal fluid (CSF) associated with signature AD pathology and to explore their relationships with measures reflecting AD-rel...

Background: Neuroinflammation has gained increasing attention as a potential contributing factor in the onset and progression of Alzheimer's disease (AD). The objective of this study was to examine the association of selected cerebrospinal fluid (CSF) inflammatory and neuronal degeneration markers with signature CSF AD profile and cognitive functi...

Neuroplasticity forms the basis for neuronal circuit complexity and differences between otherwise similar circuits. We show that the Microphthalmia-associated transcription factor (Mitf) plays a central role in intrinsic plasticity of olfactory bulb (OB) projection neurons. Mitral and tufted (M/T) neurons from Mitf mutant mice are hyperexcitable, h...

Background Neuroinflammation has gained increasing attention as a potential contributing factor in the onset and progression of Alzheimer‘s disease (AD). The objective of this study was to examine the association of selected cerebrospinal fluid (CSF) inflammatory and neuronal degeneration markers with signature CSF AD profile and cognitive function...

Background Neuroinflammation has gained increasing attention as a potential contributing factor in the onset and progression of Alzheimer‘s disease (AD). The objective of this study was to examine the association of selected cerebrospinal fluid (CSF) inflammatory and neuronal degeneration markers with signature CSF AD profile and cognitive function...

Neuroplasticity forms the basis for neuronal circuit complexity and can determine differences between otherwise similar circuits. Although synaptic plasticity is fairly well characterized, much less is known about the molecular mechanisms underlying intrinsic plasticity, especially its transcriptional regulation. We show that the Microphthalmia-ass...

Purpose The inflammatory markers chitinase-3-like protein 1 (CHI3L1) and chitotriosidase (CHIT1) have both been associated with cardiovascular complications. The aim of this preliminary observational study was to assess the roles and interaction of obstructive sleep apnea (OSA) severity and body mass index (BMI) with plasma CHI3L1 levels and CHIT1...

Although mast cell distribution has been described in both human and canine hearts, cardiac mast cells in mice have yet to be categorically localized. We therefore sought to describe mast cell distribution within the mouse heart and characterize their dependence on the Microphthalmia-associated transcription factor (Mitf). Cardiac mast cells were v...

Melanocytes are pigment producing cells derived from the neural crest. They are primarily found in the skin and hair follicles, but can also be found in other tissues including the eye, ear and heart. Here, we describe the distribution of pigmented cells in C57BL/6J mouse meninges, the membranes that envelope the brain. These cells contain melanoso...

Introduction: Acellular fish skin of the Atlantic cod (Gadus morhua) is being used to treat chronic wounds. The prevalence of diabetes and the comorbidity of chronic wounds is increasing globally. The aim of the study was to assess the biocompatibility and biological characteristics of acellular fish skin, important for tissue repair. Materials a...

Chitosan, the deacetylated derivative of chitin, is used as biomaterial in diverse settings. It is also found on pathogens and can be pro-inflammatory. Shorter derivatives of chitosan can be generated chemically or enzymatically - chitosan oligosaccharides (ChOS). There is variation in the chemical composition of ChOS, including size distribution,...

Metal implants and polymeric devices for the application in the clinical treatment of orthopedic tissue injuries are increasingly coated with bioactive biomaterials derived from natural substances to induce desirable biological effects. Many metals and polymers used in biomaterials research show high affinity for endotoxins, which are abundant in t...

A mutation in the human cystatin C gene leads to familial cerebral amyloid angiopathy. This disease is known as "hereditary cerebral hemorrhage with amyloidosis-Icelandic type" or "hereditary cystatin C amyloid angiopathy." The mutant cystatin C protein forms aggregates and amyloid, within the central nervous system almost exclusively in connection...

Key roles of macroglia are inextricably coupled to specialized membrane domains. The perivascular endfoot membrane has drawn particular attention, as this domain contains a unique complement of aquaporin-4 (AQP4) and other channel proteins that distinguishes it from perisynaptic membranes. Recent studies indicate that the polarization of macroglia...

Biomaterials research has been expanding over the last decade, in part to provide improved medical devices for the treatment of orthopedic tissue injuries. In the quest to provide the best performance combined with low cost for medical implants, an increasing number of non-chemists have entered the field of biomaterials research without the profoun...

Chitooligosaccharides are of interest as potential drugs due to their bioactivity and water solubility. We compared the effect of acetylated and deacetylated chitooligomers (Hexamers) on short-term expansion (7 days) and osteogenic differentiation of bone-marrow derived, human mesenchymal stem cells in terms of gene expression, cytokine secretion a...

Human mesenchymal stem cells (hMSC) can be expanded in vitro and differentiated towards osteogenic, chondrogenic or adipogenic lineages, making them an attractive source for tissue engineering and regenerative medicine. Chitinase-like-proteins (CLPs) belong to the family 18 glycosyl hydrolases and are believed to play a role in inflammation and tis...

Expression of the water channel aquaporin-4 (AQP4) at the blood-brain interface is dependent upon the dystrophin associated protein complex. Here we investigated whether deletion of the Aqp4 gene affects the molecular composition of this protein scaffold and the integrity of the blood-brain barrier. High-resolution immunogold cytochemistry revealed...

AQP9 is an aquaglyceroporin that serves important functions in peripheral organs, including the liver. Reflecting the lack of AQP9 knockout mice, uncertainties still prevail regarding the localization and roles of AQP9 in the central nervous system. Here we present a comprehensive analysis of AQP9 gene expression in brain, based on a quantitative a...

It has long been a common view that neurons in the human central nervous system were not capable of self renewal. But in the mid-1990s scientists discovered that certain areas of the human brain do have the ability generate new neurons, at least under certain circumstances. It was subsecuently confirmed that the human central nervous system contain...

Neðst á síðunni er hægt að nálgast greinina í heild sinni með því að smella á hlekkinn View/Open It has long been a common view that neurons in the human central nervous system were not capable of self renewal. But in the mid-1990s scientists discovered that certain areas of the human brain do have the ability generate new neurons, at least under c...

Mammalian neural progenitor cells divide asymmetrically to self-renew and produce a neuron by segregating cytosolic Numb proteins primarily to one daughter cell. Numb signaling specifies progenitor over neuronal fates but, paradoxically, also promotes neuronal differentiation. Here we report that ACBD3 is a Numb partner in cell-fate specification....

Asymmetric cell division is an attractive means to diversify cell fates during development and for stem cells to balance self-renewal and differentiation. In Drosophila, two signaling pathways, one mediated by Numb and the other by Notch, play essential but antagonistic roles in enabling the two daughters to adopt different fates after a wide varie...

Aquaporins are a family of water channels found in animals, plants, and microorganisms. A subfamily of aquaporins, the aquaglyceroporins, are permeable for water as well as certain solutes such as glycerol, lactate, and urea. Here we show that the brain contains two isoforms of AQP9--an aquaglyceroporin with a particularly broad substrate specifici...

Sequence variation of a 250–bp (base pair) fragment of the mitochondrial cytochrome b gene has been studied using polymerase chain reaction and direct sequencing of 519 Atlantic cod Gadus morhua from Iceland and 78 cod from Greenland. Twenty-four variable nucleotide sites, mostly silent, define 34 haplotypes. The amount of variation is high (?C=0·7...

Neural progenitor cells in the developing neocortex change over time to produce different neurons, a phenomenon that is also observed in other regions of the nervous system. Mouse Numb (also known as m-numb) and Numbl (also known as numblike or Nbl) are redundant but essential in maintaining virtually all progenitor cells during early neurogenesis....

Many anatomical differences exist between males and females; these are manifested on a molecular level by different hormonal environments. Although several molecular differences in adult tissues have been identified, a comprehensive investigation of the gene expression differences between males and females has not been performed. We surveyed the ex...

Neurons in most regions of the mammalian nervous system are generated over an extended period of time during development. Maintaining sufficient numbers of progenitors over the course of neurogenesis is essential to ensure that neural cells are produced in correct numbers and diverse types. The underlying molecular mechanisms, like those governing...

We studied sequence variation of a fragment of the mitochondrial cytochrome b gene using polymerase chain reaction (PCR) and direct sequencing of 109 Atlantic cod (Gadus morhua) from the Baltic and 19 cod from the White Sea. Eight nucleotide substitutions define 12 haplotypes differing from each other by one to six substitutions. All mutations are...

Thesis (Ph. D.)--Yale University, 2004. Microfilm. s