Targeting cardiomyocyte ADAM10 ectodomain shedding promotes survival early after myocardial infarction.

After myocardial infarction the innate immune response is pivotal in clearing of tissue debris as well as scar formation, but exaggerated cytokine and chemokine secretion with subsequent leukocyte infiltration also leads to further tissue damage. Here, we address the value of targeting a previously unknown a disintegrin and metalloprotease 10 (ADAM10)/CX3CL1 axis in the regulation of neutrophil recruitment early after MI. We show that myocardial ADAM10 is distinctly upregulated in myocardial biopsies from patients with ischemia-driven cardiomyopathy. Intriguingly, upon MI in mice, pharmacological ADAM10 inhibition as well as genetic cardiomycyte-specific ADAM10 deletion improves survival with markedly enhanced heart function and reduced scar size. Mechanistically, abolished ADAM10-mediated CX3CL1 ectodomain shedding leads to diminished IL-1ß-dependent inflammation, reduced neutrophil bone marrow egress as well as myocardial tissue infiltration. Thus, our data shows a conceptual insight into how acute MI induces chemotactic signaling via ectodomain shedding in cardiomyocytes.

Synthesis of 13C Labeled Vitamin D Metabolites for Their Use in LC-MS/MS: Valuable Tools for Cancer Research and Other Applications.

BACKGROUND/AIM: Simultaneous assessment of various vitamin D metabolites in human biofluids by liquid chromatography tandem mass spectrometry (LC-MS/MS) represents a new promising tool for the differential diagnosis of vitamin D-related diseases. Particularly, besides 25(OH)VD2/3, low-abundant medicinally relevant vitamin D metabolites, such as 24,25(OH)2VD2/3, 1,25(OH)2VD2/3, and 1,24,25(OH)3VD2/3, along with their 3-epi-derivatives have to be considered. MATERIALS AND METHODS: The assessment of these metabolites by LC-MS/MS requires the development of calibration and reference standards, that is, their labeling with multiple deuterium-, or even better, 13C- atoms. RESULTS: Overall, 10 13C-labeled vitamin D metabolites have been chemically synthesized and obtained in good yield and high purity. CONCLUSION: Access to a wide variety of 13C-labeled highly pure vitamin D metabolites enables the advancement of LC-MS/MS applications towards a better understanding of differential diagnosis of vitamin D-related diseases.

Efficient synthesis of 3-TBDMS-11α,25-dihydroxyvitamin D3 and D2 ethers.

Vitamin D deficiency might cause a wide variety of human disorders. As a prerequisite for appropriate diagnosis and therapy, medicinally relevant vitamin D metabolites have to be assayed most accurately and with high specificity. It has been demonstrated, that vitamin D conjugates, linked via a hydroxyl group at C11, might be promising for the development of highly specific antibodies to be employed in competitive protein binding assays. The connective synthesis of 3-TBDMS-11α,25-dihydroxyvitamin D3 and D2 ethers in 500 mg scale, starting from vitamin D2, is described. For installation of a hydroxyl group at C11 a sequence of Pd(OAc)2 mediated oxidation of an enone, epoxidation and subsequent epoxide ring opening was applied to obtain a suitable CD-ring precursor, that was connected with an A-ring diphenylphosphine oxide by Wittig-Horner reaction. Finally, an appropriate side chain was installed, respectively.

Optimization of Chemical Syntheses of Vitamin D C3-Epimers.

Due to the widespread impact of vitamin D on human health, the development of appropriate assays to detect deficiency of all vitamin D metabolites of pharmacological interest is being continuously improved. Although over 50 naturally-occurring metabolites of vitamin D are known to date, only very few are routinely detected in commercially available assays. This is particularly true regarding C3-epimers of vitamin D3 and D2, which not only may interfere in analytical measurements with other metabolites of interest, but also have controversial and not yet fully understood physiological functions. In this study we optimized a synthetic method to obtain various vitamin D3 and D2 C3-epimers in order to make them available in gram quantities for further evaluation and for their use in assay development or drug discovery. Particularly, the inversion of the C3-OH group at the A-ring of vitamin D2, which, in turn, serves as a suitable starting material for most of chemical syntheses of vitamin D metabolites, can be converted to the corresponding C3-epimer under so-called "Mitsunobu conditions". Thus, the C3-OH group is converted into the corresponding ester by treatment with an aromatic acid, subsequent addition of an azodicarboxlate and triphenylphoshine, leading to the corresponding ester, concomitant to the inversion of the stereogenic center at C3. Reduction or saponification of the resulting ester finally leads to the corresponding C3-epimer, that may serve as starting material for a wide variety of vitamin D3 and D2 C3-epimers.

Development of efficient chemical syntheses of vitamin D degradation products.

In recent years it has been recognized that vitamin D deficiency is associated with a wide range of diseases, including various types of cancers. Due to the enormous medical importance of vitamin D and its metabolites, their status in blood serum has to be accurately measured. Thus, the metabolites actually used as reference standards and also others of relevant biological activity have to be provided for validation and continuous improvement of appropriate diagnostic devices. Efficient chemical syntheses of vitamin D derivatives described in the literature are herein proven in a comparative study and applied to the synthesis of some of the most relevant natural metabolites as representative examples.

Combined Na(+)/Ca(2+) exchanger and L-type calcium channel block as a potential strategy to suppress arrhythmias and maintain ventricular function.

BACKGROUND: L-type calcium channel (LTCC) and Na(+)/Ca(2+) exchanger (NCX) have been implicated in repolarization-dependent arrhythmias, but also modulate calcium and contractility. Although LTCC inhibition is negative inotropic, NCX inhibition has the opposite effect. Combined block may, therefore, offer an advantage for hemodynamics and antiarrhythmic efficiency, particularly in diseased hearts. In a model of proarrhythmia, the dog with chronic atrioventricular block, we investigated whether combined inhibition of NCX and LTCC with SEA-0400 is effective against dofetilide-induced torsade de pointes arrhythmias (TdP), while maintaining calcium homeostasis and hemodynamics. METHODS AND RESULTS: Left ventricular pressure (LVP) and ECG were monitored during infusion of SEA-0400 and verapamil in anesthetized dogs. Different doses were tested against dofetilide-induced TdP in chronic atrioventricular block dogs. In ventricular myocytes, effects of SEA-0400 were tested on action potentials, calcium transients, and early afterdepolarizations. In cardiomyocytes, SEA-0400 (1 µmol/L) blocked 66±3% of outward NCX, 50±2% of inward NCX, and 33±9% of LTCC current. SEA-0400 had no effect on systolic calcium, but slowed relaxation, despite action potential shortening, and increased diastolic calcium. SEA-0400 stabilized dofetilide-induced lability of repolarization and suppressed early afterdepolarizations. In vivo, SEA-0400 (0.4 and 0.8 mg/kg) had no effect on left ventricular pressure and suppressed dofetilide-induced TdPs dose dependently. Verapamil (0.3 mg/kg) also inhibited TdP, but caused a 15±8% drop of left ventricular pressure. A lower dose of verapamil without effects on left ventricular pressure (0.06 mg/kg) was not antiarrhythmic. CONCLUSIONS: In chronic atrioventricular block dogs, SEA-0400 treatment is effective against TdP. Unlike specific inhibition of LTCC, combined NCX and LTCC inhibition has no negative effects on cardiac hemodynamics.

Intrathecal hydromorphone for postoperative analgesia after cesarean delivery: a retrospective study.

Despite compelling evidence for the safety and efficacy of intrathecal hydromorphone, the use of this opioid intrathecally for the pain management of patients undergoing cesarean delivery has not been widely accepted. The purpose of this retrospective study was to compare the reported efficacy and safety of pain management in women who received intrathecal hydromorphone (100 microg) vs in women who received intrathecal fentanyl (25 microg) or a local anesthetic for their cesarean delivery. The author hypothesized that intrathecal hydromorphone because of its known pharmacodynamics would provide better postoperative analgesia within the first 24 hours after cesarean delivery. The results of this retrospective chart review confirmed the hypothesis that intrathecal hydromorphone possesses the appropriate pharmacodynamics to facilitate optimal pain relief in patients undergoing cesarean delivery. It provided a comparable onset of effective pain relief, as well as a significantly prolonged duration of pain relief (P < .001) compared with intrathecal fentanyl or local anesthetic. Traditionally, intrathecal morphine was the opioid of choice for prolonged pain management during cesarean deliveries in which spinal anesthesia was selected. However, intrathecal hydromorphone was shown to be an effective and possibly even better substitute. Further research on intrathecal hydromorphone is needed.

Intrathecal hydromorphone for cesarean delivery: in search of improved postoperative pain management: a case report.

Currently, morphine and fentanyl are the most commonly used intrathecal opioids for the postoperative pain management of patients who underwent cesarean delivery. Unfortunately, the analgesic benefits of these 2 drugs tend to fall into different extremes based on lipid solubility. Intrathecal hydromorphone may provide more consistent analgesia because its lipid solubility falls between that of the other 2 opioids. A 22-year-old woman with a 39-week intrauterine pregnancy, gravida 2, para 1, came in for a scheduled second-time cesarean delivery. Her preoperative history included a morphine allergy discovered when administered intrathecally during her first cesarean delivery. Thus, in this case, preservative-free hydromorphone, 100 microg, was administered intrathecally as the opioid replacement for the spinal anesthetic. Intrathecal hydromorphone was found to have provided superior pain relief with fewer side effects in this patient, who received intrathecal morphine for the same surgery 2 years earlier. This case report supports an emerging hypothesis that intrathecal hydromorphone is not only safe but possibly more effective than other intrathecal opioids for pain management after cesarean delivery. The purpose of this case report is to encourage the development of more research regarding this use of intrathecal hydromorphone.

Long-range interactions and evolutionary stability in a predator-prey system.

Evolving ecosystems often are dominated by spatially local dynamics, but many also include long-range transport that mixes spatially separated groups. The existence of such mixing may be of critical importance since research shows spatial separation may be responsible for long-term stability of predator-prey systems. Complete mixing results in rapid global extinction, while spatial systems achive long term stability due to an inhomogeneous spatial pattern of local extinctions. We consider the robustness of a generic evolving predator-prey or host-pathogen model to long-range mixing and find a transition to global extinction at nontrivial values implying that even if significant mixing already exists, a small amount of additional mixing may cause extinction. Our results are relevant to the global mixing of species due to human intervention and to global transport of infectious disease.

Estimating the total genetic diversity of a spatial field population from a sample and implications of its dependence on habitat area.

The total genetic diversity of a species is a key factor in its persistence and conservation. Because realistic sample sizes are far smaller than the total population, it is impractical to exhaustively characterize diversity of most populations. Here, we demonstrate the possibility of calculating the genetic diversity of a spatial population from a sample using genealogical models. We trace the history of a population by simulating the locations of the ancestors of a particular sample of the population backwards in time. We use this method to estimate the genetic diversity of the global population of Pseudomonas bacteria. The same results are obtained whether using a global sample or a subsample restricted to a particular geographic region (California). The results are also validated by comparing additional predictions of the model to the data. Furthermore, we use these results to show that the level of genetic diversity in a population depends strongly on the size of its habitat, much more strongly than does biodiversity as measured by the number of species. The strong dependence of diversity on habitat area has significant implications for conservation strategies.

Theory predicts the uneven distribution of genetic diversity within species.

Global efforts to conserve species have been strongly influenced by the heterogeneous distribution of species diversity across the Earth. This is manifest in conservation efforts focused on diversity hotspots. The conservation of genetic diversity within an individual species is an important factor in its survival in the face of environmental changes and disease. Here we show that diversity within species is also distributed unevenly. Using simple genealogical models, we show that genetic distinctiveness has a scale-free power law distribution. This property implies that a disproportionate fraction of the diversity is concentrated in small sub-populations, even when the population is well-mixed. Small groups are of such importance to overall population diversity that even without extrinsic perturbations, there are large fluctuations in diversity owing to extinctions of these small groups. We also show that diversity can be geographically non-uniform--potentially including sharp boundaries between distantly related organisms--without extrinsic causes such as barriers to gene flow or past migration events. We obtained these results by studying the fundamental scaling properties of genealogical trees. Our theoretical results agree with field data from global samples of Pseudomonas bacteria. Contrary to previous studies, our results imply that diversity loss owing to severe extinction events is high, and focusing conservation efforts on highly distinctive groups can save much of the diversity.

The role of trans-membrane signal transduction in turing-type cellular pattern formation.

The Turing mechanism (Phil. Trans. R. Soc. B 237 (1952) 37) for the production of a broken spatial symmetry in an initially homogeneous system of reacting and diffusing substances has attracted much interest as a potential model for certain aspects of morphogenesis (Models of Biological Pattern Formation, Academic Press, London, 1982; Nature 376 (1995) 765) such as pre-patterning in the embryo. The two features necessary for the formation of Turing patterns are short-range autocatalysis and long-range inhibition (Kybernetik 12 (1972) 30) which usually only occur when the diffusion rate of the inhibitor is significantly greater than that of the activator. This observation has sometimes been used to cast doubt on applicability of the Turing mechanism to cellular patterning since many messenger molecules that diffuse between cells do so at more-or-less similar rates. Here we show that Turing-type patterns will be able to robustly form under a wide variety of realistic physiological conditions though plausible mechanisms of intra-cellular chemical communication without relying on differences in diffusion rates. In the mechanism we propose, reactions occur within cells. Signal transduction leads to the production of messenger molecules, which diffuse between cells at approximately equal rates, coupling the reactions occurring in different cells. These mechanisms also suggest how this process can be controlled in a rather precise way by the genetic machinery of the cell.

Dynamics and genealogy of strains in spatially extended host-pathogen models.

We examine the dynamics of evolution in a generic spatial model of a pathogen infecting a population of hosts, or an analogous predator-prey system. Previous studies of this model have found a range of interesting phenomena that differ from the well-mixed version. We extend these studies by examining the spatial and temporal dynamics of strains using genealogical tracing. When transmissibility can evolve by mutation, strains of intermediate transmissibility dominate even though high-transmissibility mutants have a short-term reproductive advantage. Mutant strains continually arise and grow rapidly for many generations but eventually go extinct before dominating the system. We find that, after a number of generations, the mutant pathogen characteristics strongly impact the spatial distribution of their local host environment, even when there are diverse types coexisting. Extinction is due to the depletion of susceptibles in the local environment of these mutant strains. Studies of spatial and genealogical relatedness reveal the self-organized spatial clustering of strains that enables their impact on the local environment. Thus, we find that selection acts against the high-transmissibility strains on long time-scales as a result of the feedback due to environmental change. Our study shows that averages over space or time should not be assumed to adequately describe the evolutionary dynamics of spatially distributed host-pathogen systems.