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Genetics
Published in Manoj Ramachandran, Tom Nunn, Basic Orthopaedic Sciences, 2018
Peter Calder, Harish Hosalkar, Aresh Hashemi-Nejad
Chromosomes are composed of DNA, ribonucleic acid (RNA), polysaccharides and histone and non-histone proteins. Normally chromosomes cannot be seen under a light microscope, but during cell division they become condensed, allowing visualization at 1000× magnification. Chromosomes are thin thread-like structures that have a short p arm and a long q arm separated by a constriction known as the centromere (Figure 2.1). The chromosomes have three basic shapes depending on the centromere location. Metacentric chromosomes have p and q arms of approximately equal length, e.g. chromosome 1. Submetacentric chromosomes have p and q arms of differing lengths, e.g. chromosome 6. In acrocentric chromosomes, the centromere is near one end and, therefore, there is a very small p arm and a correspondingly longer q arm, e.g. chromosome 13.
Molecular Biology
Published in John C Watkinson, Raymond W Clarke, Louise Jayne Clark, Adam J Donne, R James A England, Hisham M Mehanna, Gerald William McGarry, Sean Carrie, Basic Sciences Endocrine Surgery Rhinology, 2018
Michael Kuo, Richard M. Irving, Eric K. Parkinson
Each DNA molecule is packaged into a chromosome by complex folding of the DNA around proteins. Diploid human cells contain 22 pairs of autosomes (1 to 22) and a pair of sex chromosomes (XX or XY) that determines the sex of the organism. One of each pair of chromosomes is maternally inherited and the other is paternally inherited. Each chromosome has a distinctive shape, size and banding pattern, but have the common appearance of two arms apparently separated by a constriction. The centromere is microscopically recognizable as the central constriction separating the chromosome into a long arm (q for queue) and a short arm (p for petit), but its biological role lies in anchoring the chromosome to the mitotic spindle for segregation during cell division. The ends of the chromosomes are capped by telomeres, which are specialized structures containing unique simple repetitive sequences. They maintain the structural integrity of the chromosome and provide a solution for complete replication of the extreme ends of the chromosome. The conventional nomenclature for chromosomal locus assignment is given by the chromosome number, followed by the arm and finally the position on the arm, for example, 3p21 indicates position 21(two-one) on the short arm of chromosome three.
Rheumatology
Published in Fazal-I-Akbar Danish, Essential Lists of Differential Diagnoses for MRCP with diagnostic hints, 2017
Patterns of staining of ANA:1 Homogeneous: a SLE.2 Speckled: a MCTD.b Sjögren’s syndrome.3 Nucleolar: a Systemic sclerosis.4 Centromere: a CREST syndrome.
Recent innovations in the screening and diagnosis of systemic sclerosis-associated interstitial lung disease
Published in Expert Review of Clinical Immunology, 2023
Ashima Makol, Vivek Nagaraja, Chiemezie Amadi, Janelle Vu Pugashetti, Elaine Caoili, Dinesh Khanna
Autoantibodies represent the serologic hallmark of SSc, well-studied as diagnostic and prognostic markers of disease-related complications. They have also been shown to be associated with ILD in patients with known SSc. Among these, the autoantibody most often associated with the presence of ILD is ATA [34,63–66]. Additionally, anti Th/To ribonucleoprotein antibodies and anti PM/Scl have also been shown to be associated with ILD, though these antibodies are not as highly prevalent in SSc [67,68]. In two large multi-center cohorts, the Canadian Scleroderma Research Group registry and the German Network for Systemic Scleroderma Registry, the presence of Anti-SSA/Ro was found to be associated with at least a two-fold increased odds of ILD [69,70]. On the contrary, anti-centromere antibodies appear to be ‘relatively protective’ and associated with decreased likelihood of progressive ILD [34,71]. While these antibodies carry an association with the presence of ILD, they are not unique to lung-specific disease activity and also correlate with extrapulmonary SSc complications. Therefore, the use of blood-based biomarkers alone cannot replace gold-standard HRCT to evaluate for ILD. While we recommend that all patients with SSc be screened for ILD, there still exists some variation in practice pattern, with some clinicians and patients choosing to defer HRCT imaging. In these situations, elevated levels of these ILD-associated autoantibodies can be used as a risk stratification tool and when present should signal a higher risk of ILD in patients with SSc prompting HRCT acquisition.
Upper gastrointestinal vascular ectasia: an under-recognized complication of systemic sclerosis
Published in Scandinavian Journal of Rheumatology, 2021
R Shukla, R Warner, P Whorwell, AL Herrick
GAVE has been reported to be associated with high body mass index, a history of systemic hypertension, low diffusing capacity of the lungs for carbon monoxide, and reduced frequency of pulmonary fibrosis on computed tomography scan (1, 3). There is also an association with autoantibodies. Several studies have now highlighted the strong negative correlation between anti-Scl70 and anti-U1-RNP antibodies and GAVE in SSc (1, 3). A EUSTAR case–control study (1) found that anti-RNA polymerase III (a risk factor for vascular complications of SSc including renal crisis) was associated with GAVE, but this association was not observed in the SCOT trial (3). Both of our patients were anti-centromere antibody positive. Although anti-centromere antibody is also associated with a vascular phenotype in patients with SSc, anti-centromere was not found to be associated with GAVE (3).
Hair straightening products and the risk of occupational formaldehyde exposure in hairstylists
Published in Drug and Chemical Toxicology, 2020
Mohamed A. Aglan, Ghada N. Mansour
The local genotoxic effect of FA is attributed to its ability to dissolve in mucosal tissue at the site of contact due to its high-water solubility and its interaction with proteins and other macromolecules (Medinsky and Bond 2001). According to ATSDR (Agency for Toxic Substances and Disease Registry (ATSDR) 2010) FA itself “not its metabolite” is capable of directly reacting with DNA and producing genotoxic effects in portal-of-entry tissues, especially when biotransformation capacities are exceeded. In order to explain how FA reaches the blood to elicit toxic effects although it is a highly reactive gas, Zhang et al. (2010) claimed that, interaction of FA with human haemato-poietic stem cells circulating in the blood and/or interaction of FA with primitive pluripotent stem cells in nasal/oral passages, lastly, FA in aqueous solution is converted mostly to methanediol (the hydrated form of FA) that may travel through the blood where it is in equilibrium with reactive FA which once generated, can react with cellular macromolecules producing toxic injuries. Iarmarcovai et al. (2007) reported an increase in centromere-positive micronuclei with a single centromere in MN frequency in PBL obtained from pathologists and anatomists exposed to FA and claimed that impaired chromosome migration may contribute to aneuploidy following prolonged exposure to FA. This is can be supported by a human bio-monitoring study which reported increased frequencies of centromere-positive MN (induction of aneuploidy) in workers exposed to FA (Orsière et al. 2006).