The cell and tissues
Peate Ian, Dutton Helen in Acute Nursing Care, 2020
The centrosome is an area near the nucleus that contains a pair of rod-like structures called the centrioles. This area and the centrioles are associated with the process of cell division. They produce the mitotic spindle in dividing cells. The centrioles also form the basis of cilia and flagella. Cilia are typically found on the columnar epithelium of the lining of the respiratory tract. They are involved in the movement of dust particles and mucus up the respiratory tract. The only example found in humans of a cell with a flagellum is the sperm.
Radiation Hormesis in Cancer
T. D. Luckey in Radiation Hormesis, 2020
The operators can make no medical claims. Federal and state regulations are followed to limit daily exposures. Facilities are spartan. No personal attendants, nurses, or doctors make this a resort or medical atmosphere. The dust and walls assure exposure to gamma rays from uranium, radium, and progeny radionuclides as well as alpha rays from inhaled and absorbed radon and progeny. Wooden floors and a variety of seats with minimum lighting leave little to do but to read or make new friends during each hour’s visit underground. Thousands of testimonials emphasize relief from sinusitis, arthritis, bursitis, prostate swellings, and kindred ailments. Reservations must be made in summer time, not in winter. Data relating cancer mortality in smokers and nonsmokers are not convincing. Animal data and some human data suggest that smoke captures microparticulates of radon progeny from the air. This allows cilia and mucus to transport the larger particulates from bronchi and trachea into the intestinal tract where they are readily eliminated. Thus, one BEIR IV conclusion may be questioned for light smokers: “…most of the increased risk is in smokers in whom the risk is 10 or more times greater than that in nonsmokers.”Other conclusions were more cautious: “…the relevant data did not lead to a conclusive description of the interaction between radon daughters and cigarette smoking for the induction of lung cancer”; “Our review suggests that this issue has yet to be resolved”; and “More important, there cannot be enough evidence from epidemiological studies to acertain the effects at low doses.”
Understanding investigations in ENT
Rogan J Corbridge in Essential ENT, 2011
The lining of the nose is covered with ciliated respiratory epithelium. It is important that these cilia function properly so that secretions of the nasal cavity and sinuses are cleared. Both congenital and acquired conditions can lead to ciliary dysfunction. The saccharin taste test is used to test the ciliary clearance of a fragment of saccharin placed on the anterior end of the inferior turbinate. Ciliary action passes the saccharin backwards and eventually it is deposited into the oropharynx, whereupon the patient first notices the sweet taste. A clearance time of more than 20 minutes is considered abnormal. It is important to ensure that the patient can in fact taste saccharin, since a small number of normal people find this substance tasteless. Ciliary brushings taken from the nasal cavity, and transported in an appropriate medium, can be examined with electron microscopy to reveal both the structure and the beat frequency of the cilia. Abnormalities of either of these may lead to clinical disease.
An experimental and computational analysis of primary cilia deflection under fluid flow
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2014
Matthew E. Downs, An M. Nguyen, Florian A. Herzog, David A. Hoey, Christopher R. Jacobs
In this study we have developed a novel model of the deflection of primary cilia experiencing fluid flow accounting for phenomena not previously considered. Specifically, we developed a large rotation formulation that accounts for rotation at the base of the cilium, the initial shape of the cilium and fluid drag at high deflection angles. We utilised this model to analyse full 3D data-sets of primary cilia deflecting under fluid flow acquired with high-speed confocal microscopy. We found a wide variety of previously unreported bending shapes and behaviours. We also analysed post-flow relaxation patterns. Results from our combined experimental and theoretical approach suggest that the average flexural rigidity of primary cilia might be higher than previously reported (Schwartz et al. 1997, Am J Physiol. 272(1 Pt 2):F132–F138). In addition our findings indicate that the mechanics of primary cilia are richly varied and mechanisms may exist to alter their mechanical behaviour.
From the cytoplasm into the cilium: Bon voyage
Published in Organogenesis, 2014
Jarema Malicki, Tomer Avidor-Reiss
The primary cilium compartmentalizes a tiny fraction of the cell surface and volume, yet many proteins are highly enriched in this area and so efficient mechanisms are necessary to concentrate them in the ciliary compartment. Here we review mechanisms that are thought to deliver protein cargo to the base of cilia and are likely to interact with ciliary gating mechanisms. Given the immense variety of ciliary cytosolic and transmembrane proteins, it is almost certain that multiple, albeit frequently interconnected, pathways mediate this process. It is also clear that none of these pathways is fully understood at the present time. Mechanisms that are discussed below facilitate ciliary localization of structural and signaling molecules, which include receptors, G-proteins, ion channels, and enzymes. These mechanisms form a basis for every aspect of cilia function in early embryonic patterning, organ morphogenesis, sensory perception and elsewhere.
Primary ciliary dyskinesia: recent advances in epidemiology, diagnosis, management and relationship with the expanding spectrum of ciliopathy
Published in Expert Review of Respiratory Medicine, 2012
Human cilia were once thought merely to be important in respiratory mucociliary clearance, with primary ciliary dyskinesia (PCD) the sole manifestation of ciliary dysfunction. There are now known to be three types of cilia: primary, nodal and motile. Cilia are complex, likely involving more than 1000 gene products; in this review, recent advances in PCD genetics, and the potential relationships with genes causing other ciliopathies, are discussed. PCD is the most important respiratory disease, characterized by upper and lower airway infection and inflammation and disorders of laterality. Ciliary gene mutations are now known to cause single organ disease, as well as complex syndromes. The focus of the review is primarily PCD, in the context of the expanding ciliopathy spectrum. The authors consider the clinical situations in which ciliary disease should be considered, and the implications for specialist respiratory practice.
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