Forensic autopsy-confirmed thrombosis-related deaths: the danger in the bones.

Thrombosis is a potentially life-threatening condition related to roughly a quarter of all deaths globally. Many of these deaths occur inside healthcare facilities due to possibly preventable causes. Therefore, understanding the etiological factors involved in excessive thrombosis may significantly contribute to the successful identification, management and education of people who have an increased risk of thrombosis. We performed a retrospective file-audit of all forensic autopsy reports conducted at the Free State Forensic Pathology Mortuary in Bloemfontein, South Africa, over 10 years. We collected the age at death, gender and ethnicity of each person included in the study. The presence and location of the thrombosis and any underlying disorder or disease were noted. The overall prevalence of thrombosis for the total study population was 0.97%. Pulmonary embolisms (PE's) were much more common than coronary thromboses. Most PE's had known contributory risk factors, where coronary thrombosis-related deaths occurred suddenly without known risk factors. Bone fractures were the most prominent risk factor associated with PE's. Females of African descent had a consistently high prevalence of thrombosis after the age of 30 years. Males of European descent showed an unexpected peak in prevalence during the 4th decade. Since most deaths occurred in patients with conditions known to contribute to venous thrombosis, we conclude that intensified public awareness efforts are required in our region to assist the general public in identifying risk factors for thrombosis, thereby decreasing the burden this potentially preventable disorder places on society.

HLA major allele group frequencies in a diverse population of the Free State Province, South Africa.

BACKGROUND: Human Leucocyte Antigens (HLA) play a vital role in disease pathogenesis and transplant rejection. HLA-typing is a useful tool in predicting disease progression and to identify potential organ donors. Due to human migration and known ethnic variation, frequent targeted HLA sequencing of specific populations is crucial to increase their representation in global reference panels. MATERIALS AND METHODS: We performed a retrospective file audit of all HLA-typings done in our setting from 2005-2019. We discuss data for the major HLA-A, HLA-B, HLA-C, and HLA-DRB1 allele groups. RESULTS: Overall, the most common allele groups were HLA-A∗02, HLA-B∗15, HLA-C∗07 and HLA-DRB1∗03. For the African descent group, the most common alleles were HLA-A∗30, HLA-B∗15, HLA-C∗07 and HLA-DRB1∗03. For the European descent group, the most common alleles were HLA-A∗02, HLA-B∗07, HLA-C∗07 and HLA-DRB1∗15. For the mixed ancestry group, the most common allele groups were HLA-A∗02, HLA-B∗15, HLA-C∗02 and HLA-DRB1∗13. HLA-B∗44 was identified as the most common allele group in patients with renal failure. DISCUSSION AND CONCLUSION: The significant variation within the HLA frequencies between the different ethnic groups highlights the value of population-specific HLA-typing. Furthermore, the identification of HLA-B∗44 as a prominent HLA in our renal failure population warrants in-depth investigation of this group.

Molecular suitability of the chacma baboon in human-targeted Von Willebrand factor directed studies.

BACKGROUND: Von Willebrand factor (VWF) has a central role in primary haemostasis and is a popular pharmaceutical target in the prevention and treatment of disorders such as acute coronary syndrome and thrombotic thrombocytopenic purpura. We have evaluated numerous possible treatments targeting VWF in the chacma baboon. Unfortunately, no data exist regarding the molecular similarity of the chacma baboon and human VWF protein, resulting in limited translatability of results. METHODS: Sanger sequencing was performed of the functionally vital VWF exon 28. The sequences were then compared to the human reference sequence. RESULTS: The baboon and human VWF amino acid sequences were 99.1% similar, with only 4 radical amino acid changes found. No radical amino acid changes were found within the functionally vital areas of the amino acid sequence. CONCLUSION: The chacma baboon VWF is similar enough to the human to produce reliable and translatable pre-clinical results with human-targeted anti-VWF agents.

Lifestyle Change Alone Sufficient to Lower Cholesterol in Male Patient With Moderately Elevated Cholesterol: A Case Report.

Background. Cardiovascular disease is a major cause of deaths. Elevated cholesterol levels to above the normal reference range is a major risk factor for developing cardiovascular disease. Current guidelines recommend the use of cholesterol-lowering drugs to lower cholesterol levels to within the normal reference range. However, the American Heart Association further recommends a change in lifestyle in managing cholesterol levels. Thus, cholesterol-lowering drugs may not be needed if a lifestyle-change alone is sufficient in lowering cholesterol levels to within normal ranges. Unfortunately, limited examples exist in academic literature to illustrate the effectiveness of lifestyle change alone in lowering of cholesterol levels. Case report. We report a case of a 33-year-old man, with moderately elevated cholesterol levels and a family history of cardiovascular disease. Method. The man followed an altered healthy fat diet accompanied with moderate exercise for 6 weeks, without the addition of cholesterol-lowering agents. Results. At the 6-week follow-up, he was able to decrease his total cholesterol by 40.25% and low-density lipid cholesterol by 52.8%, to within normal ranges. The cholesterol levels remained within normal ranges after 6 months. Conclusion. This case illustrates that in some individuals, lifestyle change alone is sufficient to lower moderately elevated cholesterol levels.

Comparison of Commercially Available Blood Collection Tubes Containing Sodium Citrate and Hirudin in Platelet Aggregation Testing.

BACKGROUND Platelet reactivity assessment is an important tool in both the causal determination of bleeding diathesis as well as in the evaluation of the efficacy of anti-platelet therapy in patients at risk of thrombosis. Sodium citrate is the most widely used anticoagulant for hemostasis investigations. However, some doubt exists over the suitability of sodium citrate in platelet function testing. Hirudin has been suggested as a superior replacement. Nevertheless, only 1 study compared citrated and hirudin treated samples with light transmission aggregometry. Therefore, limited evidence exists to conclusively prove the supremacy of hirudin over sodium citrate in light transmission aggregometry. The aim of our study was to compare citrated and hirudin treated samples, collected in commercially available blood collection tubes, using the 5 most common agonists, with light transmission aggregometry. MATERIAL AND METHODS Blood was obtained from 20 healthy volunteers. Platelet counts were performed on platelet-rich plasma. Light transmission aggregometry was performed within 4 h of sample collection using ADP, collagen, arachidonic acid, epinephrine, and ristocetin as agonists. RESULTS Platelet counts for the respective anticoagulants did not differ significantly. ADP-induced aggregation was comparable between the samples. However, among all the agonists, hirudin-treated platelets had significantly weaker aggregatory responses. CONCLUSIONS Commercially available sodium citrate should remain the anticoagulant of choice for routine platelet function testing in our setting. However, the time limitation associated with the use of sodium citrate in platelet function testing remains a concern. Thus, alternative anticoagulants should still be explored.

Comparison of common platelet receptors between the chacma baboon (Papio ursinus) and human for use in pre-clinical human-targeted anti-platelet studies.

Anti-platelet agents play a central part in the treatment and prevention of acute thrombotic events. Discriminating animal models are needed for the development of novel agents. The chacma baboon has been extensively used as a model to evaluate anti-platelet agents. However, limited data exist to prove the translatability of this species to humans. We aimed to determine the suitability of the chacma baboon in preclinical human targeted GPIIb/IIIa, GPIbα and P2Y12 studies. Light-transmission platelet aggregometry (LTA), whole blood impedance aggregometry, receptor number quantification and genomic DNA sequencing were performed. Baboon ADP and arachidonic acid-induced LTA aggregation results differed significantly from human values, even at increased concentrations. LTA ristocetin-induced agglutination was comparable between species, but baboon platelets needed twice the concentration of ristocetin to elicit a similar response. Citrated baboon blood had significantly less aggregation than humans when evaluated with impedance aggregometry. However, hirudinised baboon whole blood gave similar aggregation as humans at the same agonist concentrations. GPIIb, GPIIIa and GPIbα numbers were significantly more on the baboon platelets. None of the amino acids deemed vital for receptor function, ligand binding or receptor inhibition, were radically different between the species. However, a conservative change in a calcium-binding region of GPIIb may render the baboon platelets more sensitive to calcium-binding agents. The chacma baboon may be used for the evaluation of human-targeted GPIIb/IIIa-, GPIbα- and P2Y12-inhibiting agents. However, the best anticoagulant, optimal agonist concentrations, increase in receptor number and sequence differences must be considered for any future studies.

The Cape Chacma baboon is not suitable for evaluating human targeted anti-GPVI agents.

An effective and safe anti-platelet drug is central to the management of patients with acute coronary syndrome (ACS). Glycoprotein VI (GPVI) is currently regarded as a potential target for novel anti-platelet agents due to its collagen-binding potential. Development of anti-thrombotics is associated with testing in animals. We have previously successfully evaluated anti-platelet drugs in the Cape Chacma baboon (Papio ursinus). However, various anti-GPVI agents did not have an effect on baboons when evaluated in our arterial thrombosis model. To evaluate the suitability of baboons for GPVI studies, we performed collagen-induced platelet aggregation, GPVI quantification and DNA sequencing. Baboon platelets needed double the amount of collagen compared to human platelets to illicit proper aggregation. GPVI quantification was unsuccessful due to non-binding of monoclonal antibodies. Sequencing of the GPVI gene revealed 36 SNPs leading to 14 amino acid changes, as well as a 9 bp deletion causing a 3 amino acid deletion. Several of the amino acid changes were within the ligand binding region of GPVI, causing limited binding of humanized anti-GPVI antibodies to the baboon platelets. Therefore, the baboon was deemed not suitable to evaluate human targeted anti-GPVI agents.