A5007218876- melanin and skin pigmentation
- Skin Protection and Aging
- Biochemical Analysis and Sensing Techniques
- Advanced Proteomics Techniques and Applications
- Signaling Pathways in Disease
- Metabolomics and Mass Spectrometry Studies
- Mass Spectrometry Techniques and Applications
- RNA Interference and Gene Delivery
- Olfactory and Sensory Function Studies
- Cutaneous Melanoma Detection and Management
- Genomics, phytochemicals, and oxidative stress
- Phytochemicals and Antioxidant Activities
- RNA regulation and disease
- Diabetes, Cardiovascular Risks, and Lipoproteins
- Clinical Laboratory Practices and Quality Control
- T-cell and B-cell Immunology
- Telomeres, Telomerase, and Senescence
- Lipoproteins and Cardiovascular Health
- Renal Transplantation Outcomes and Treatments
- Viral Infectious Diseases and Gene Expression in Insects
- Hyperglycemia and glycemic control in critically ill and hospitalized patients
- Biosimilars and Bioanalytical Methods
- Dye analysis and toxicity
- Cancer-related Molecular Pathways
- Immunotherapy and Immune Responses
Leiden University Medical Center
2013-2024
Amsterdam University Medical Centers
2024
Vrije Universiteit Amsterdam
2024
Hospital Clínic de Barcelona
2021
Umm al-Qura University
2021
Université de Yaoundé I
2021
University of Bamenda
2021
Bezmiâlem Vakıf Üniversitesi
2021
Benue State University
2021
Charles University
2011
Tyrosinase (EC 1.14.18.1) exhibits unusual kinetic properties in the oxidation of monohydric phenol substrates consisting a lag period that increases with increasing substrate concentration. The cause this is an autocatalytic process dependent on generation dihydric substrate, which acts as activator enzyme. Experiments N-substituted (N-methyldopamine,N-acetyldopamine) demonstrate oxygen consumption retarded N-acetyl substituted material due to diminished rate cyclization. uptake exhibited...
Abstract BACKGROUND Direct and calculated measures of lipoprotein fractions for cardiovascular risk assessment suffer from analytical inaccuracy in certain dyslipidemic pathological states, most commonly hypertriglyceridemia. LC-MS/MS has proven suitable multiplexed quantification phenotyping apolipoproteins. We developed provisionally validated an automated assay apolipoprotein (apo) A-I, B, C-I, C-II, C-III, E simultaneous qualitative apoE phenotypes. METHODS used 5 value-assigned human...
Background: The melanoma susceptibility locus cyclin-dependent kinase inhibitor 2A encodes two unrelated cell growth inhibitors, p16 and alternative reading frame (ARF). In fibroblasts, both proteins are implicated in cellular senescence, a key barrier to tumor development. coding sequence is more often mutated families than the ARF sequence. To investigate role of melanocytes, we assessed aspects growth, apoptosis, immortalization melanocytes cultured from patients, whom had inactive...
Melanin synthesis is an oxygen-dependent process that acts as a potential source of reactive oxygen species (ROS) inside pigment-forming cells. The the lighter variant melanin, pheomelanin, consumes cysteine and this may limit capacity cellular antioxidative defense. We show tyrosine-induced melanogenesis in cultured normal human melanocytes (NHM) accompanied by increased production ROS decreased concentration intracellular glutathione. Clinical atypical (dysplastic) nevi (DN) regularly...
Protein mass spectrometry (MS) is an enabling technology that ideally suited for precision diagnostics. In contrast to immunoassays with indirect readouts, MS quantifications are multiplexed and include identification of proteoforms in a direct manner. Although widely used routine measurements drugs metabolites, the number clinical MS-based protein applications limited. this paper, we share our experience aim take away concerns have kept laboratory medicine from implementing quantitative MS....
A combination of techniques, including high-performance liquid chromatography (HPLC), spectrophotometric measurements, and a novel method for quantifying melanosome morphology, were applied to the analysis melanin content composition in highly pigmented (Fitzpatrick type V VI) human skin. We found that total epidermal is significantly elevated photoexposed VI skin (approximately 1.6 x), while individual components suggests pheomelanin increases only slightly, whereas...
Clinically actionable quantification of protein biomarkers by mass spectrometry (MS) requires analytical performance in concordance with quality specifications for diagnostic tests. Laboratory-developed tests should, therefore, be validated accordance EN ISO 15189:2012 guidelines medical laboratories to demonstrate competence and traceability along the entire workflow, including selected standardization strategy phases before, during, after proteolysis. In this study, bias imprecision a...
Implementation of quantitative clinical chemistry proteomics (qCCP) requires targeted approaches, usually involving bottom-up multiple reaction monitoring-mass spectrometry (MRM-MS) with stable-isotope labeled standard (SIS) peptides, to move toward more accurate measurements. Two aspects qCCP that deserve special attention are (1) proper calibration and (2) the assurance consistent digestion. Here, we describe evaluation tryptic digestion efficiency by monitoring various signature missed...
The goal of this investigation was to correlate the melanin content in human pigmentary cells with generation UVB-induced photoproducts and examine relationship between removal photoproducts. Cultured melanocytes from light-skinned individuals synthesized less produced more cyclobutane pyrimidine dimers 6-4 upon UVB exposure than did black skin. Tyrosine-stimulated melanogenesis provided protection against DNA damage both cell types. In another set pigmented lines a ratio eumelanin...
The observed correlation between ultraviolet light incidence and skin color, together with the geographical apportionment of reflectance among human populations, suggests an adaptive value for pigmentation skin. We have used Affymetrix U133a v2.0 gene expression microarrays to investigate profiles a total 9 melanocyte cell lines (5 from lightly pigmented donors 4 darkly donors) plus their respective unirradiated controls. In order reveal signatures selection in loci bearing on humans, we...
The pheo/eumelanin ratio of cultured normal human melanocytes is distinct from the observed for same cells in vivo where they are close contact with keratinocytes. To study possible involvement keratinocytes control melanogenesis, we compared quantitatively and qualitatively melanin production melanocyte mono-cultures, melanocyte-keratinocyte co-cultures pigmented reconstructed epidermis. Pheomelanin eumelanin contents were assessed by high-performance liquid chromatography electrochemical...