Disease Entities as Natural Kinds
Lawrie Reznek in The Nature of Disease, 1987
The reason, I think, why there is not a determinate number of substances (even though they fall into natural kinds), is that substances do not form a higher-order natural kind. And hence we cannot examine the natures of the substances to examine which are and which are not different substances. To make this point clearer, I think that we can argue that there is a determinate number of elements. This is because elements do form a higher-order natural kind - they all share a common type of nature, namely, electronic structure or atomic number. It is this that enables us to say that deuterium is merely a different form of the same element of hydrogen, because it shares with hydrogen its electronic structure, or the number of protons in the nucleus. (It is a different isotopic natural kind because it has a different number of nucleons in its nucleus.) So it is because elements constitute a higher-order natural kind that we can defend the idea that there is a determinate number of them, while conversely it is because substances do not form a higher-order natural kind that there is not.
Radioactivity and Radiotracers
Graham Lappin, Simon Temple in Radiotracers in Drug Development, 2006
Whilst the number of protons in the atomic nucleus is fixed for any given element, the number of neutrons can vary. The number of protons (Z) plus the number of neutrons (N) in the nucleus defines the atomic mass (A). Thus A=Z+N. Atoms of the same element with different numbers of neutrons are known as isotopes. Thus isotopes of the same element will have the same value for Z but a different atomic mass (A). (Frederick Soddy introduced the term isotope in 1914 and received a Nobel Prize in 1921).1 Take hydrogen for example. The atom of the most abundant isotope of hydrogen (99.99%) has one proton (Z=1) and one electron but no neutrons (N=0) and hence it has an atomic mass of one (A=1). Deuterium (0.015% natural abundance) on the other hand has one proton (Z =1) and one neutron (N=1) and hence has an atomic mass of two (A=2). Isotopes are denoted by prefixing the atomic mass in superscript and the atomic number in subscript, thus . Hydrogen, for example is represented by the symbol . Deuterium is represented by . A third configuration of hydrogen exists where the nucleus contains two neutrons (-tritium). (For completeness, isotopes of hydrogen above tritium are known but they have very short half-lives (2.7) and therefore are not relevant here).
Normal Values for Cadmium in Human Tissues, Blood, and Urine in Different Countries
Lars Friberg, Tord Kjellström, Carl-Gustaf Elinder, Gunnar F. Nordberg in Cadmium and Health: A Toxicological and Epidemiological Appraisal, 2019
In human placenta, the average cadmium concentration has been reported to be in the order of 20 to 150 μg/kg dry weight, which corresponds to about 3 to 24 μg/kg on a wet weight basis.12,13,82,97 Thürauf et al.98 reported almost ten times higher values, but since deuterium background correction was not reported as being used during the analysis, the actual concentration may well be lower. Piscator,79 using a spectrographic method, arrived at an average of 10 μg/kg wet weight. Roels et al.82 and Copius-Peereboom et al.12 noticed that women smoking 15 to 25 cigarettes per day had almost twice the cadmium concentration (83 μg/kg dry weight) compared to nonsmoking women (46 μg/kg dry weight).
Deuterium Depleted Water Inhibits the Proliferation of Human MCF7 Breast Cancer Cell Lines by Inducing Cell Cycle Arrest
Published in Nutrition and Cancer, 2019
Kamal Yavari, Lida Kooshesh
Deuterium is the heavier stable isotope of hydrogen. Since 1992, great importance has been attached to the deuterium content in water. It has been known for decades there exist strong mass differences between hydrogen and deuterium and their different masses cause these isotopes to behave differently in chemical reactions. The concentration of deuterium is about 150 ppm (over 16 mM/L) in regular water and 12–14 mM/L in living organisms. In order to reveal the possible role of naturally occurring D in living organisms, the replacement of regular water with deuterium-depleted water (DDW) in a range from 25 to 125 ppm was investigated in cell cultures. As a control of these experiments, regular water (150 ppm) was considered to compare the effects of decreasing the amount of dutrium in biological systems.
HDX-MS study on garadacimab binding to activated FXII reveals potential binding interfaces through differential solvent exposure
Published in mAbs, 2023
Saw Yen Ow, Eugene A. Kapp, Vesna Tomasetig, Anton Zalewski, Jason Simmonds, Con Panousis, Michael J. Wilson, Andrew D. Nash, Matthias Pelzing
All the measurements described above were repeated to create a triplicate dataset (n = 3). Evaluation of significance from the differential kinetics of deuteration was intrinsic to the study of garadacimab via the measurement of pre-/post binding along the Fc section of the molecule (between Phe-270 and Val-271, and Ile-386 and Leu-407, containing the solvent-exposed Met-261 and the Asn-Gly motif at Asn-393) as these regions were not expected to interact with β-FXIIa. The significant difference between the free and the complexed state was determined to be ±0.15 units of deuterium at a 99.7% confidence interval (3× standard deviation; Figures S5 and S6), indicating that a differential uptake of ≤0.15 units of deuterium was not considered significant.40 This value was therefore used to evaluate the significance of the subsequent deuterium kinetics datasets. The average hydrogen back-exchange was assessed using maximally labeled cytochrome C model protein as per the guidance white paper,40 and determined to be ~36% (see Supplementary methods M2 and M3, Figure S7 for additional detail).19,40,41
ALSUntangled No. 47: RT001
Published in Amyotrophic Lateral Sclerosis and Frontotemporal Degeneration, 2019
Richard Bedlack
RT001 is an orally administered compound being developed by the pharmaceutical startup company Retrotope (1) for patients with Friedreich’s ataxia, an inherited neurodegenerative disease. The company website suggests broad potential usefulness in other neurodegenerative disorders including ALS. Chemically, RT001 is a modified polyunsaturated fatty acid (PUFA) with an omega-6 structure (1). Two of the normal hydrogen atoms have been replaced with deuterium atoms (D-PUFA). Mechanistically, this change allows it to reduce the oxidative stress-induced damage in a unique way as described below. RT001 is not FDA-approved yet for any disease and is currently only available through Retrotope’s clinical trials and expanded access programs. An expanded access program for PALS was recently created (2).
Related Knowledge Centers
- Atom
- Helium
- Nuclear Magnetic Resonance
- Radioactive Decay
- Tritium
- Hydrogen
- Atomic Nucleus
- Heavy Water
- Microwave Spectroscopy
- Deuterium Nmr