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Published in Ken Addley, MCQs, MEQs and OSPEs in Occupational Medicine, 2023
Best fit. Carboxyhaemoglobin concentrations are typically less than 10% in smokers. Carbon monoxide results in the oxyhemoglobin dissociation curve shifting to the left impairing oxygen delivery to the tissues. Carbon monoxide is a by-product of incomplete combustion of carbon fuels. Carbon monoxide is generated in the human body by the catabolism of heme and results in the normal baseline human carboxyhemoglobin level of 0.4–1%.
Neuroanatomy and Brain Perfusion in Functional Somatic Syndromes
Published in Peter Manu, The Psychopathology of Functional Somatic Syndromes, 2020
Functional magnetic resonance imaging was used by investigators from Vanderbilt University, Nashville, Tennessee, to study central nervous system changes during painful stimulation in patients with irritable bowel syndrome (Mertz et al., 2000). The technique measured the ratio of oxyhemoglobin to deoxyhemoglobin, which was considered a marker for the local blood flow and metabolic activity. The activated area produced a magnetic resonance signal of higher intensity and allowed the precise definition of the activated anatomical site. The subjects recruited for the study included 16 patients with irritable bowel syndrome (14 women and two men with a mean age of 33 years) and 18 age- and gender-matched healthy individuals. The control subjects were free of abdominal pain and other complaints attributable to the gastrointestinal tract. Organic disease was ruled out in all participants by history and physical examination, comprehensive laboratory testing, and sigmoidoscopy or other endoscopic procedures.
The Respiratory System and Its Disorders
Published in Walter F. Stanaszek, Mary J. Stanaszek, Robert J. Holt, Steven Strauss, Understanding Medical Terms, 2020
Walter F. Stanaszek, Mary J. Stanaszek, Robert J. Holt, Steven Strauss
The process by which oxygen passes from the alveoli into the bloodstream and carbon dioxide passes from the bloodstream into the alveoli is diffusion. Once the carbon dioxide from the blood reaches the alveoli, it is forced up and out. through the respiratory passages during expiration (Figure 9.2). The oxygen that has entered the bloodstream is carried to cells throughout the body by the protein molecule called hemoglobin. The term oxyhemoglobin refers to the molecule of hemoglobin when it is combined with oxygen.
Comparative effectiveness among available treatments in difficult-to-treat port-wine stains (PWS): a Network Meta-Analysis of observational evidence
Published in Journal of Dermatological Treatment, 2023
Sirinda Jamjanya, Voraphol Vejjabhinanta, Krittai Tanasombatkul, Phichayut Phinyo
From the principle of selective photothermolysis, the best treatment for PWS should be a laser set to damage the hemoglobin determined by wavelength, appropriate energy to heat red blood cells and vessel endothelium, and a pulse duration equal to or less than the thermal relaxation time of vessels with a diameter of about 20 µm (45). The absorption coefficient of oxyhemoglobin also affects the response to treatment. The oxyhemoglobin absorption peaks at 418, 452, and 577 nm, whereas 577 nm induces a better penetration depth (0.5 mm) and less absorption by melanin. The 585 nm wavelength found similar vascular absorption but had deeper penetration (1.2 mm) (46). Theoretically, longer wavelengths, a larger spot size, higher fluence, and a longer pulse duration tend to increase treatment efficacy (31). In difficult-to-treat PWS, the deeper and more ectatic vessels may respond better to a longer pulse duration (more than 0.45 ms). The optimum pulse duration for most PWS, which have a diameter of 20–150 µm (18,47) should be set between 1 and 10 msec (48,49).
Understanding persistent breathlessness: impact on patients and optimal approaches to symptomatic reduction – an overview
Published in Expert Review of Respiratory Medicine, 2023
Diana H. Ferreira, Slavica Kochovska, Vanessa N. Brunelli, David C. Currow
Because persistent breathlessness is subjective, self-report is the required measure [55]. Clinically, tools may assist in identifying people with persistent breathlessness and assessing its impact. However, such tools need to be complemented with discussions on severity, consequences and meaning of breathlessness for each person. Breathlessness may be accompanied by dysfunctional breathing, such as an increased respiratory rate, use of accessory muscles or decreased oxyhemoglobin saturation. While signs may reflect the severity of the underlying disease(s), they cannot reflect the experience of breathlessness. Given the disparities between what is seen and felt, breathlessness ratings vary widely between clinicians and patients [56,57]. People often report not feeling breathless, because they have adapted their lives to avoid breathing discomfort by forgoing activities [58,59]. Objective measures such as lung volumes and standardized, self-paced, exercise-capacity tests (e.g. 6-minute walk test [6-MWT], sit-to-stand test) have been used to try to provide an indication of breathlessness severity and its impact on function. However, concordance between objective measures and subjective breathlessness is surprisingly low, with self-reported measures of breathlessness being a better predictor of health-related outcomes [49]. The 3-minute constant rate stair stepping (3-MST) and shuttle walking tests (3-MWT) were recently recommended over self-paced exercise tests because they allow quantification of breathlessness to a standardized exercise level [60].
Co-delivery of carbonic anhydrase IX inhibitor and doxorubicin as a promising approach to address hypoxia-induced chemoresistance
Published in Drug Delivery, 2022
Muhammad Umair Amin, Sajid Ali, Muhammad Yasir Ali, Dominik C. Fuhrmann, Imran Tariq, Benjamin S. Seitz, Eduard Preis, Jana Brüßler, Bernhard Brüne, Udo Bakowsky
The determination of hemolysis was based on the extent of erythrocyte destruction and release of hemoglobin because of their interaction with different formulations. Free hemoglobin in the presence of atmospheric oxygen is converted to oxyhemoglobin which can be detected spectrophotometrically. The results of the hemolysis assay are shown in Figure 8(b), where free Dox, MSNPs, and Dox-MSNPs have shown hemolytic effects. The destruction of erythrocytes is attributed to the surface density of the silanol group of MSNPs (Bharti et al., 2015). On the other hand, CA-IX enzyme inhibitor-loaded liposomes have shown lower hemolytic effects. In the lipid coated formulations, the hemolytic effects of free Dox and MSNPs were significantly masked because of the biocompatible nature of liposomes.