Potent and selective inhibition of the structurally homologous proteases of coagulation poses challenges for drug development. Hematophagous organisms frequently accomplish this by fashioning peptide ...inhibitors combining exosite and active site binding motifs. Inspired by this biological strategy, we create several EXACT inhibitors targeting thrombin and factor Xa de novo by linking EXosite-binding aptamers with small molecule ACTive site inhibitors. The aptamer component within the EXACT inhibitor (1) synergizes with and enhances the potency of small-molecule active site inhibitors by many hundred-fold (2) can redirect an active site inhibitor's selectivity towards a different protease, and (3) enable efficient reversal of inhibition by an antidote that disrupts bivalent binding. One EXACT inhibitor, HD22-7A-DAB, demonstrates extraordinary anticoagulation activity, exhibiting great potential as a potent, rapid onset anticoagulant to support cardiovascular surgeries. Using this generalizable molecular engineering strategy, selective, potent, and rapidly reversible EXACT inhibitors can be created against many enzymes through simple oligonucleotide conjugation for numerous research and therapeutic applications.
Unfractionated heparin (UFH), the standard anticoagulant for cardiopulmonary bypass (CPB) surgery, carries a risk of post-operative bleeding and is potentially harmful in patients with ...heparin-induced thrombocytopenia-associated antibodies. To improve the activity of an alternative anticoagulant, the RNA aptamer 11F7t, we solved X-ray crystal structures of the aptamer bound to factor Xa (FXa). The finding that 11F7t did not bind the catalytic site suggested that it could complement small-molecule FXa inhibitors. We demonstrate that combinations of 11F7t and catalytic-site FXa inhibitors enhance anticoagulation in purified reaction mixtures and plasma. Aptamer-drug combinations prevented clot formation as effectively as UFH in human blood circulated in an extracorporeal oxygenator circuit that mimicked CPB, while avoiding side effects of UFH. An antidote could promptly neutralize the anticoagulant effects of both FXa inhibitors. Our results suggest that drugs and aptamers with shared targets can be combined to exert more specific and potent effects than either agent alone.
The purpose is to study the age trajectory of hand-grip strength after the age of 45 years.
In this study, we use data from three large nationwide population-based surveys of Danes aged 45 to 102 ...years with a total of 8342 participants with grip-strength measurements and up to 4 years of follow-up. Grip strength was measured by using a portable hand dynamometer.
Grip strength declines throughout life for both males and females, but among the oldest women, the longitudinal curve reaches a horizontal plateau. The course of the decline is estimated by using full information in the longitudinal data and is found to be almost linear in the age span of 50 to 85 years. In this age span, mean annual grip-strength loss is estimated to be 0.59 (0.02) (SE) kg for men and 0.31 (0.01) kg for women.
This study confirms the previously reported grip-strength decline with increasing age. Estimates were obtained by using full-information methods from large population-representative studies. Equations of expected grip strength, as well as tables with sex-, age-, and height-stratified reference data, provide an opportunity to include grip-strength measurement in clinical care in similar populations.
Known limitations of unfractionated heparin (UFH) have encouraged the evaluation of anticoagulant aptamers as alternatives to UFH in highly procoagulant settings such as cardiopulmonary bypass (CPB). ...Despite progress, these efforts have not been totally successful. We take a different approach and explore whether properties of an anticoagulant aptamer can complement UFH, rather than replace it, to address shortcomings with UFH use. Combining RNA aptamer 11F7t, which targets factor X/Xa, with UFH (or low molecular weight heparin) yields a significantly enhanced anticoagulant cocktail effective in normal and COVID-19 patient blood. This aptamer-UFH combination (1) supports continuous circulation of human blood through an
membrane oxygenation circuit, as is required for patients undergoing CPB and COVID-19 patients requiring extracorporeal membrane oxygenation, (2) allows for a reduced level of UFH to be employed, (3) more effectively limits thrombin generation compared to UFH alone, and (4) is rapidly reversed by the administration of protamine sulfate, the standard treatment for reversing UFH clinically following CPB. Thus, the combination of factor X/Xa aptamer and UFH has significantly improved anticoagulant properties compared to UFH alone and underscores the potential of RNA aptamers to improve medical management of acute care patients requiring potent yet rapidly reversible anticoagulation.
Peripheral blood-derived endothelial cells (pBD-ECs) are an attractive tool for cell therapies and tissue engineering, but have been limited by their low isolation yield. We increase pBD-EC yield via ...administration of the chemokine receptor type 4 antagonist AMD3100, as well as via a diluted whole blood incubation (DWBI).
Porcine pBD-ECs were isolated using AMD3100 and DWBI and tested for EC markers, acetylated LDL uptake, growth kinetics, metabolic activity, flow-mediated nitric oxide production and seeded onto titanium tubes implanted into vessels of pigs.
DWBI increased the yield of porcine pBD-ECs 6.6-fold, and AMD3100 increased the yield 4.5-fold. AMD3100-mobilized ECs were phenotypically indistinguishable from nonmobilized ECs. In porcine implants, the cells expressed endothelial nitric oxide synthase, reduced thrombin-antithrombin complex systemically and prevented thrombosis.
Administration of AMD3100 and the DWBI method both increase pBD-EC yield.
PURPOSE: Studies of younger individuals have suggested an association between ACE genotype and physical and cognitive performance. Using a longitudinal study of elderly twins we studied the ...association between ACE genotype and physical and cognitive functioning and survival in old age.
METHODS: Participants were 684 twins aged 73+ years from the 1997 and 1999 surveys of the Longitudinal Study of Aging Danish Twins. Cognitive skills were assessed by the MMSE, while physical abilities were determined through self-report in 1997 and through both self-report and measurement of performance in two physical tasks in 1999. Survival status was obtained through linkage with a national death register.
RESULTS: Neither physical nor cognitive performance was associated with ACE genotype at baseline in 1997, or at follow-up in 1999. For participants in both surveys longitudinal changes in these skills did not depend on ACE genotype. The relative risk of dying was increased in II compared with the DI and DD genotype with relative risks of 1.6 (95 percent confidence intervals 1.1–2.5) and 1.3 (0.8–2.1), respectively.
CONCLUSION: We found no substantial effects of ACE genotype on physical and cognitive performance, or rate of change among elderly. Persons with the D allele may have a lower mortality at older ages.
Genetic-evolutionary theories of aging predict that the genetic variance for fitness traits increases with age, while epidemiological-gerontological theories predict an increase in the environmental ...variance for most traits. In this study we examine the age trajectories of the genetic and environmental variance in physical functioning in a sample of 4731 Danish twins aged 70+ who are being followed longitudinally every second year with up to four assessments completed. A biometric growth model (Neale and McArdle, 2000) was applied to a validated physical ability score. The model included an overall level effect, a rate of linear change effect, and residual effects. The best-fitting model was a sex-specific model including additive genetic and nonshared environmental factors affecting level and rate of change and only nonshared environmental factors affecting the wave-specific levels. For both sexes there is an approximate doubling of both the total variance and the genetic variance in the physical ability score over the four waves and, hence, a rather stable heritability. However, the heritability is approximately.10 for males and.30 for females in all four waves. The heritability of level and slope showed a similar pattern:.11-14 in males and.35-.39 in females. The increase in both additive genetic variance and environmental variance is in agreement with genetic-evolutionary and epidemiological-gerontological theories of aging, respectively. The present study suggests that overall level of strength may be a better phenotype for future molecular genetic studies on physical functioning in the elderly than rate of change, because rate of change is vulnerable to sample attrition due to mortality and dropout and because four waves were needed to be able to detect a heritability for rate of change of the same magnitude as the heritability for level of physical functioning.
Seven anticoagulants besides unfractionated heparin have been used for human cardiopulmonary bypass (CPB), mainly in patients with heparin-induced thrombocytopenia. The collective experience with ...these alternative anticoagulants provides a perspective on current efforts aimed at improving CPB anticoagulation. Unfortunately, each alternative currently lacks a standard dosing schedule and a reliable method of monitoring the adequacy of its anticoagulant effect during CPB. Most also lack proven antidotes. Thus, unfractionated heparin remains the anticoagulant of choice for standard CPB.
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