By Peter Laird, MD
The long awaited Lufkin DaVita bleach murder case is on the verge of commencing with the early salvos by the prosecution and the defense coming to light in a recent hearing on the admissibility of evidence. (here) An immediate question that arises out of an early report is what is 3-chlorotyrosine and why is it an important part of the prosecution evidence?
“The court needs to understand that at no time did the state or prosecution find bleach in blood, but instead found 3-chlorotyrosine,” Deaton said.
In addressing Deaton’s issues with the research’s validity, Angelina County District Attorney Clyde Herrington chronicled the death of one of Saenz’s alleged victims, a man the prosecutor said entered the dialysis center in good shape but did not leave that way.
“He was carried by his wife that morning (to the center). He was in good spirits. He laughed, he joked, he ate a boiled egg. He’s doing fine and the next thing you know, he’s unconscious,” Herrington said. “He died three to four months later.”
“Massive levels” of 3-chlorotyrosine were present in the man’s body, Herrington said. Defense team member Thomas W. Deaton attributed the patient’s 3-chlorotyrosine level to a “massive infection.”
There is no pathogneumonic test for bleach infusion. (A sign or symptom that is so characteristic of a disease that it makes the diagnosis). The prosecution and the defense have already started to square off over the issue of 3-chlorotyrosine allegedly found in some of the alleged victims of Kimberly Saenz. 3-cholortyrosine is not an ordinary blood test performed in a doctors office or in a dialysis clinic. It is a very obscure research tool for elucidating exposure to chlorinating agents. There are only a handful of clinical studies measuring both the natural levels of 3-chlorotyrosine as a marker of inflammation and infections for instance.
Neutrophilic polymorphonuclear leukocytes (neutrophils) are highly specialized for their primary function, the phagocytosis and destruction of microorganisms. When coated with opsonins (generally complement and/or antibody), microorganisms bind to specific receptors on the surface of the phagocyte and invagination of the cell membrane occurs with the incorporation of the microorganism into an intracellular phagosome. There follows a burst of oxygen consumption, and much, if not all, of the extra oxygen consumed is converted to highly reactive oxygen species. In addition, the cytoplasmic granules discharge their contents into the phagosome, and death of the ingested microorganism soon follows. Among the antimicrobial systems formed in the phagosome is one consisting of myeloperoxidase (MPO), released into the phagosome during the degranulation process, hydrogen peroxide (H2O2), formed by the respiratory burst and a halide, particularly chloride. The initial product of the MPO-H2O2-chloride system is hypochlorous acid, and subsequent formation of chlorine, chloramines, hydroxyl radicals, singlet oxygen, and ozone has been proposed. These same toxic agents can be released to the outside of the cell, where they may attack normal tissue and thus contribute to the pathogenesis of disease. This review will consider the potential sources of H2O2 for the MPO-H2O2-halide system; the toxic products of the MPO system; the evidence for MPO involvement in the microbicidal activity of neutrophils; the involvement of MPO-independent antimicrobial systems; and the role of the MPO system in tissue injury. It is concluded that the MPO system plays an important role in the microbicidal activity of phagocytes.
There is only one study I am aware of at this point looking at naturally occuring 3-chlorotyrosine levels in dialysis patients by Dr. Himmlefarb.
Oxidative stress has been implicated in the cardiovascular complications that affect chronic renal failure patients on hemodialysis, though the physiologically relevant pathways mediating oxidative damage are poorly understood. It is known, however, that hemodialysis activates neutrophils, a well-characterized source of hydrogen peroxide and myeloperoxidase. The phagocyte-derived myeloperoxidase-hydrogen peroxide-chloride system generates hypochlorous acid, which reacts with tyrosine residues of proteins to form 3-chlorotyrosine. To explore the role of activated phagocytes in oxidative stress in chronic renal failure, we used 3-chlorotyrosine as a specific marker of myeloperoxidase activity. Utilizing isotope dilution gas chromatography-mass spectrometry, we compared 3-chlorotyrosine levels in plasma proteins of five patients on chronic hemodialysis therapy with those of age- and sex-matched healthy controls. The oxidized amino acid was present in the plasma proteins of 4 of the hemodialysis patients (3.5 +/- 0.8 micromol per mol tyrosine) but was undetectable in the healthy subjects. Therefore, one pathway for oxidative stress in hemodialysis patients appears to involve hypochlorous acid generated by the myeloperoxidase system of activated phagocytes. We also examined intradialytic 3-chlorotyrosine levels using membranes that activate white blood cells and the alternative pathway of complement. Hemodialysis increased plasma myeloperoxidase and the expression of CD11b/CD18 by circulating phagocytes, but failed to demonstrably increase 3-chlorotyrosine levels. 3-chlorotyrosine was detectable in 12 of 19 samples in total, with significant intrasubject variability. Our observations suggest that oxidants generated by myeloperoxidase contribute to the increased oxidative stress observed in renal-failure patients but do not damage plasma proteins during the hemodialysis procedure itself.
This complex little known clinical entity is suddenly thrust on the stage of a prominent murder case where it may promise more confusion than clarity. One of the questions immediately present is how well will the jurors correlate studies on chlorine gas in rats causing 3-chlorotyrosine levels compared to complex dialysis patients with multiple co-morbid conditions where naturally occurring 3-chlorotyrosine levels are already documented and applying that as evidence to proof of murder. This is only the beginning of a very long, complex case.