Pharmacological preconditioning by diazoxide downregulates cardiac L-type Ca2+ channels

BACKGROUND AND PURPOSE

Pharmacological preconditioning (PPC) with mitochondrial ATP-sensitive K⁺ (mitoK_ATP) channel openers such as diazoxide, leads to cardioprotection against ischaemia. However, effects on Ca²⁺ homeostasis during PPC, particularly changes in Ca²⁺ channel activity, are poorly understood. We investigated the effects of PPC on cardiac L-type Ca²⁺ channels.

EXPERIMENTAL APPROACH

PPC was induced in isolated hearts and enzymatically dissociated cardiomyocytes from adult rats by preincubation with diazoxide. We measured reactive oxygen species (ROS) production and Ca²⁺ signals associated with action potentials using fluorescent probes, and L-type currents using a whole-cell patch-clamp technique. Levels of the α_1c subunit of L-type channels in the cellular membrane were measured by Western blot.

KEY RESULTS

PPC was accompanied by a 50% reduction in α_1c subunit levels, and by a reversible fall in L-type current amplitude and Ca²⁺ transients. These effects were prevented by the ROS scavenger N-acetyl-L-cysteine (NAC), or by the mitoK_ATP channel blocker 5-hydroxydecanoate (5-HD). PPC signficantly reduced infarct size, an effect blocked by NAC and 5-HD. Nifedipine also conferred protection against infarction when applied during the reperfusion period. Downregulation of the α_1c subunit and Ca²⁺ channel function were prevented in part by the protease inhibitor leupeptin.

CONCLUSIONS AND IMPLICATIONS

PPC downregulated the α_1c subunit, possibly through ROS. Downregulation involved increased degradation of the Ca²⁺ channel, which in turn reduced Ca²⁺ influx, which may attenuate Ca²⁺ overload during reperfusion.     

Collection of pluripotential hematopoietic stem cells by cytapheresis

Successful complete hematopoietic reconstitution (CHR) using nonleukemic peripheral stem cells (PSC) after marrow ablation has been reported in animals but not man. Previous studies of cytapheresis products from humans, as a prelude to use for CHR, have documented the presence of committed myeloid (CFU-GM) and erythroid (BFU-E) precursors. We have examined mononuclear cell (MNC) products collected on the Fenwal CS3000 Blood Cell Separator for these plus the more primitive mixed (granulo-, erythro-, mono-, and megakaryocytic) cell colony-forming units (CFU-GEMM) and for various lymphocytic subpopulations (LSP). One to two-hour products contained 36 +/- 7 CFU- GEMM/10(6) MNC (mean +/- SE, n = 8) or 490 +/- 131/ml product. This compared favorably with blood (23 +/- .4/10(6) MNC or 46 +/- 8/ml, n = 14) and bone marrow (146 +/- 58/10(6) MNC, n = 12). Collection efficiency for E-rosette-positive cells approximated that for total lymphocytes and was variable for other LSP. Recovery of CFU-GEMM after freezing in 10% dimethylsulfoxide at a controlled rate and storage in liquid N2 was 54% +/- 8% (n = 8). Cytapheresis collection of large numbers of pluripotent hematopoietic precursors and demonstration of adequate recovery of these after cryopreservation, both previously unreported, are significant steps toward eventual CHR using nonleukemic PSC.     

Life Satisfaction and Subsequent Physical,Behavioral, and Psychosocial Health in Older Adults

Policy Points

• Several intergovernmental organizations (Organisation for Economic Co‐operation and Development, World Health Organization, United Nations) are urging countries to use well‐being indicators (e.g., life satisfaction) in addition to traditional economic indicators when making important policy decisions.
• As the number of governments implementing this new approach grows, so does the need to continue evaluating the health and well‐being outcomes we might observe from policies aimed at improving life satisfaction.
• The results of this study suggest that life satisfaction is a valuable target for policies aiming to enhance several indicators of psychosocial well‐being, health behaviors, and physical health outcomes.

ContextSeveral intergovernmental organizations (Organisation for Economic Co‐operation and Development, World Health Organization, United Nations) are urging countries to use well‐being indicators (e.g., life satisfaction) in addition to traditional economic indicators when making important policy decisions. As the number of governments implementing this new approach grows, so does the need to continue evaluating the health and well‐being outcomes we might observe from policies aimed at improving life satisfaction.MethodsWe evaluated whether positive change in life satisfaction (between t₀;2006/2008 and t₁;2010/2012) was associated with better outcomes on 35 indicators of physical, behavioral, and psychosocial health and well‐being (in t₂;2014/2016). Data were from 12,998 participants in the University of Michigan''s Health and Retirement Study—a prospective and nationally representative cohort of US adults over age 50.FindingsParticipants with the highest (versus lowest) life satisfaction had better subsequent outcomes on some physical health indicators (lower risk of pain, physical functioning limitations, and mortality; lower number of chronic conditions; and higher self‐rated health) and health behaviors (lower risk of sleep problems and more frequent physical activity), and nearly all psychosocial indicators (higher positive affect, optimism, purpose in life, mastery, health mastery, financial mastery, and likelihood of living with spouse/partner; and lower depression, depressive symptoms, hopelessness, negative affect, perceived constraints, and loneliness) over the 4‐year follow‐up period. However, life satisfaction was not subsequently associated with many specific health conditions (i.e., diabetes, hypertension, stroke, cancer, heart disease, lung disease, arthritis, overweight/obesity, or cognitive impairment), other health behaviors (i.e., binge drinking or smoking), or frequency of contact with children, family, or friends.ConclusionsThese results suggest that life satisfaction is a valuable target for policies aiming to enhance several indicators of psychosocial well‐being, health behaviors, and physical health outcomes.     

Parastomal evisceration as an extremely rare complication of a common procedure

The creation of an abdominal stoma is a common procedure performed as part of the treatment for many conditions. Common complications include poor stoma siting, high output, skin irritation, ischaemia, retraction, parastomal hernia and prolapse. An extremely rare stoma complication is parastomal evisceration. We present a case of a 48-year-old woman who presented to us with parastomal evisceration as a late complication of a transverse colostomy. It is the second case reported as acomplication of this procedure but the first that occurred after such a long postoperative period (almost 18 months).     

Iron absorption from wheat flour: effects of lemonade and chamomile infusion

ObjectiveWe measured iron bioavailability of meals based on wheat flour consumed by a vulnerable population in Latin America.MethodsBioavailability of iron (ferrous sulfate) from fortified noodles, noodle soup, noodle soup eaten with lemonade sweetened with panela (unrefined whole cane sugar), bread alone, and bread consumed with a chamomile infusion sweetened with panela was studied using the double isotopic method in 13 women.ResultsIron bioavailabilities from bread, noodles, and noodle soup were not significantly different (7.4%, 6.3%, and 6.0%, respectively). Iron absorption from noodle soup was significantly higher when given with lemonade (11.0%) compared with absorption of the same meal without lemonade (P < 0.02) or with the absorption of noodles (P < 0.04). Iron absorption of bread given alone or with chamomile infusion sweetened with panela (8%) was not significantly different.ConclusionIron bioavailability of meals based on wheat flour, fortified with ferrous sulfate, is improved when given with lemonade. The consumption of this beverage may be an alternative to further increase the effectiveness of wheat flour fortification in preventing iron deficiency in low-income Latin American populations.     

Erythropoietin production by the fetal liver in an adult environment

To gain insight into the mammalian liver to kidney erythropoietin (Ep) switch, we heterotopically transplanted livers from preswitch, switched, and postswitch fetal and newborn lambs into normal adult sheep. Recipients' serum Ep and circulating reticulocyte levels were serially determined until rejection of the graft and compared with identical samples from sham-operated control adult ewes. Transplantation of preswitch and switched fetal livers caused an impressive rise in recipients' serum Ep activity and provoked a corresponding increase in reticulocytosis. In contrast, Ep activity and reticulocyte counts did not change from preoperative levels in adult ewes transplanted with postswitch livers or in the sham-operated controls. The production of Ep by the preswitch fetal liver in the adult environment was not dependent on the presence or absence of host kidneys and was stimulated by anemic hypoxia. These results suggest that the fetal liver is capable of producing relatively large amounts of Ep activity, and the production of Ep can be maintained in the adult environment in the presence of functional adult kidneys. This argues against suppression of liver Ep production by renal Ep, or some other factor in the postnatal environment, and suggests that the liver to kidney switch of Ep production during ontogeny may represent a genetically determined event.     

Tissue-specific modulation of cyclooxygenase-2 (Cox-2) expression in the uterus and the v. cava by estrogens and phytoestrogens

Cyclooxygenase 2 (Cox-2), an enzyme involved in prostaglandin production, is a key player in the development of pathologic changes, such as colorectal cancer, arteriosclerosis and thrombosis. In this study, we investigated the effects of estrogens, selective estrogen receptor modulators (SERMs), pure antiestrogens and phytoestrogens on the tissue-specific expression of Cox-2 in the uterus and the v. cava of ovariectomized female rats. Cox-2 expression could be detected in the uterine epithelium and in the endothelium of the v. cava. Cox-2 expression was time-dependently stimulated after administration of 17beta estradiol (E2) in the uterus. In the v. cava, E2 treatment resulted in a stimulated expression of the progesterone receptor (PR), a gene known to be regulated by E2, whereas Cox-2 was simultaneously down-regulated. Administration of the pure antiestrogen faslodex (Fas) had no effect on Cox-2 expression. In contrast, administration of tamoxifen (Tam) resulted in a decrease of Cox-2 expression in the v. cava but does not stimulate Cox-2 expression in the uterus. Interestingly, the same expression pattern of Cox-2 could be detected after dose-dependent administration of genistein (Gen). Here, down-regulation of Cox-2 could already be detected after administration of merely 0.5 mg/(kgBW) Gen, a dose where no effects on uterine weight were observed. In summary, our results demonstrate a reverse tissue-specific regulation of Cox-2 expression by estrogens in the v. cava and uterus indicating the existence of complex molecular mechanisms which have to be characterized in future studies. Remarkably, Tam and the phytoestrogen Gen, both share the ability to decrease the expression of Cox-2 in the v. cava without effecting its uterine expression. These observations may be of great importance with respect to potential beneficial or adverse effects of estrogens, SERMs and phytoestrogens on the cardiovascular tissue.     

Oral treatment with genistein reduces the expression of molecular and biochemical markers of inflammation in a rat model of chronic TNBS-induced colitis

Background  Inflammatory bowel disease (IBD) in humans has a high incidence in Europe and the USA, whereas in East Asia, incidence has been historically low. The risk of IBD appears to increase in Asian immigrants adopting western lifestyles, suggesting a strong link of environmental/dietary factors in the development of IBD. Exposure to high levels of isoflavones such as genistein (Gen) in traditional East Asian diets has been associated with a decreased risk of developing breast cancer and may also be beneficial for the prevention of IBD. Aim  In this study, the effect of orally administered genistein on the inflammatory response in the TNBS-induced chronic colitis rat model was investigated. Methods  Eighteen male Wistar rats, aged 12 weeks, were randomized to one of three groups (n = 6). Two groups received a 2,4,6-trinitrobenzenesulfonic acid (TNBS) enema, then were treated daily by oral gavage with either Gen (100 mg/kg b.w.) or vehicle, for 14 days. The last group served as a control group, not receiving the TNBS enema. At the end of the 14 days, animals were killed and tissues collected. Molecular and biochemical inflammatory markers in the colon, specifically cyclooxygenase-2 (COX-2) and myeloperoxidase (MPO), were analyzed. In addition, to assess the efficacy of Gen treatment, relative wet weights of the accessory sexual organs, specifically prostate and the seminal vesicle, were compared between the groups treated or not with Gen. Results  Wet weights of both prostates and seminal vesicles were significantly (P < 0.01) reduced upon Gen administration. In the colon, expression of COX-2 mRNA and protein was reduced (P < 0.05) in the Gen treatment group, as compared to the control group, whereas there was no significant inhibitory effect of Gen on the expression of proliferating cell nuclear antigen. In Gen treated animals colon wet weight was not altered, however a decrease in MPO activity (P < 0.01) was seen. Conclusion  These results may provide evidence that oral administration of Gen exerts beneficial anti-inflammatory effects in a rodent model of TNBS-induced chronic colitis. While the sample size of this study was small, it nevertheless might encourage the realization of larger blinded randomized controlled studies for the proof of concept.