Novel Role for Cardiolipin as a Target of Therapy to Mitigate Myocardial Injury Caused by Venoarterial Extracorporeal Membrane Oxygenation

BACKGROUND

Cardiolipin is a mitochondrial-specific phospholipid that maintains integrity of the electron transport chain (ETC) and plays a central role in myocardial ischemia/reperfusion injury. Tafazzin is an enzyme that is required for cardiolipin maturation. Venoarterial extracorporeal membrane oxygenation (VA-ECMO) use to provide hemodynamic support for acute myocardial infarction has grown exponentially, is associated with poor outcomes, and is under active clinical investigation, yet the mechanistic effect of VA-ECMO on myocardial damage in acute myocardial infarction remains poorly understood. We hypothesized that VA-ECMO acutely depletes myocardial cardiolipin and exacerbates myocardial injury in acute myocardial infarction.

METHODS

We examined cardiolipin and tafazzin levels in human subjects with heart failure and healthy swine exposed to VA-ECMO and used a swine model of closed-chest myocardial ischemia/reperfusion injury to evaluate the effect of VA-ECMO on cardiolipin expression, myocardial injury, and mitochondrial function.

RESULTS

Cardiolipin and tafazzin levels are significantly reduced in the left ventricles of individuals requiring VA-ECMO compared with individuals without VA-ECMO before heart transplantation. Six hours of exposure to VA-ECMO also decreased left ventricular levels of cardiolipin and tafazzin in healthy swine compared with sham controls. To explore whether cardiolipin depletion by VA-ECMO increases infarct size, we performed left anterior descending artery occlusion for a total of 120 minutes followed by 180 minutes of reperfusion in adult swine in the presence and absence of MTP-131, an amphipathic molecule that interacts with cardiolipin to stabilize the inner mitochondrial membrane. Compared with reperfusion alone, VA-ECMO activation beginning after 90 minutes of left anterior descending artery occlusion increased infarct size (36±8% versus 48±7%; P<0.001). VA-ECMO also decreased cardiolipin and tafazzin levels, disrupted mitochondrial integrity, reduced electron transport chain function, and promoted oxidative stress. Compared with reperfusion alone or VA-ECMO before reperfusion, delivery of MTP-131 before VA-ECMO activation reduced infarct size (22±8%; P=0.03 versus reperfusion alone and P<0.001 versus VA-ECMO alone). MTP-131 restored cardiolipin and tafazzin levels, stabilized mitochondrial function, and reduced oxidative stress in the left ventricle.

CONCLUSIONS

We identified a novel mechanism by which VA-ECMO promotes myocardial injury and further identify cardiolipin as an important target of therapy to reduce infarct size and to preserve mitochondrial function in the setting of VA-ECMO for acute myocardial infarction.

Circulating Proteome Analysis Identifies Reduced Inflammation After Initiation of Hemodynamic Support with Either Veno-Arterial Extracorporeal Membrane Oxygenation or Impella in Patients with Cardiogenic Shock

In-hospital mortality associated with cardiogenic shock (CS) remains high despite the use of percutaneous assist devices. We sought to determine whether support with VA-ECMO or Impella in patients with CS alters specific components of the plasma proteome. Plasma samples were collected before device implantation and 72 h after initiation of support in 11 CS patients receiving ECMO or Impella. SOMAscan was used to detect 1305 circulating proteins. Sixty-seven proteins were changed after ECMO (18 upregulated and 49 downregulated, p < 0.05), 38 after Impella (10 upregulated and 28 downregulated, p < 0.05), and only eight proteins were commonly affected. Despite minimal protein overlap, both devices were associated with markers of reduced inflammation and increased apoptosis of inflammatory cells. In summary, ECMO and Impella are associated with reduced expression of inflammatory markers and increased markers of inflammatory cell death. These circulating proteins may serve as novel targets of therapy or biomarkers to tailor AMCS use.

Transvalvular Unloading Mitigates Ventricular Injury Due to Venoarterial Extracorporeal Membrane Oxygenation in Acute Myocardial Infarction

Whether extracorporeal membrane oxygenation (ECMO) with Impella, known as EC-Pella, limits cardiac damage in acute myocardial infarction remains unknown. The authors now report that the combination of transvalvular unloading and ECMO (EC-Pella) initiated before reperfusion reduced infarct size compared with ECMO alone before reperfusion in a preclinical model of acute myocardial infarction. EC-Pella also reduced left ventricular pressure-volume area when transvalvular unloading was applied before, not after, activation of ECMO. The authors further observed that EC-Pella increased cardioprotective signaling but failed to rescue mitochondrial dysfunction compared with ECMO alone. These findings suggest that ECMO can increase infarct size in acute myocardial infarction and that EC-Pella can mitigate this effect but also suggest that left ventricular unloading and myocardial salvage may be uncoupled in the presence of ECMO in acute myocardial infarction. These observations implicate mechanisms beyond hemodynamic load as part of the injury cascade associated with ECMO in acute myocardial infarction.

Tools for assessing health research partnership outcomes and impacts: a systematic review

OBJECTIVE

To identify and assess the globally available valid, reliable and acceptable tools for assessing health research partnership outcomes and impacts.

METHODS

We searched Ovid MEDLINE, Embase, CINAHL Plus and PsycINFO from origin to 2 June 2021, without limits, using an a priori strategy and registered protocol. We screened citations independently and in duplicate, resolving discrepancies by consensus and retaining studies involving health research partnerships, the development, use and/or assessment of tools to evaluate partnership outcomes and impacts, and reporting empirical psychometric evidence. Study, tool, psychometric and pragmatic characteristics were abstracted using a hybrid approach, then synthesized using descriptive statistics and thematic analysis. Study quality was assessed using the quality of survey studies in psychology (Q-SSP) checklist.

RESULTS

From 56 123 total citations, we screened 36 027 citations, assessed 2784 full-text papers, abstracted data from 48 studies and one companion report, and identified 58 tools. Most tools comprised surveys, questionnaires and scales. Studies used cross-sectional or mixed-method/embedded survey designs and employed quantitative and mixed methods. Both studies and tools were conceptually well grounded, focusing mainly on outcomes, then process, and less frequently on impact measurement. Multiple forms of empirical validity and reliability evidence was present for most tools; however, psychometric characteristics were inconsistently assessed and reported. We identified a subset of studies (22) and accompanying tools distinguished by their empirical psychometric, pragmatic and study quality characteristics. While our review demonstrated psychometric and pragmatic improvements over previous reviews, challenges related to health research partnership assessment and the nascency of partnership science persist.

CONCLUSION

This systematic review identified multiple tools demonstrating empirical psychometric evidence, pragmatic strength and moderate study quality. Increased attention to psychometric and pragmatic requirements in tool development, testing and reporting is key to advancing health research partnership assessment and partnership science. PROSPERO CRD42021137932.

A187 CHOLESTATIC LIVER DISEASE AND BRAIN DYSFUNCTION: ROLE OF THE ARYL HYDROCARBON RECEPTOR

Background

Cholestatic liver disease is associated with immune-mediated inflammatory liver injury. This disorder is also associated with brain dysfunction and behavioural changes, notably fatigue, depression and social withdrawal. The mechanisms leading to these central nervous system abnormalities are unknown, however, they are associated with neuroinflammation. Microglia and astrocytes are two glial populations that play key roles in neuroinflammation. Activated glia display morphological changes, secrete cytokines, and mediate electrophysiological changes, altering the normal functioning of the brain. The aryl hydrocarbon receptor (AhR) is a transcription factor involved in the immune response. AhR is present on glia and its’ activation has been shown to reduce neuroinflammation. The role of the AhR in cholestatic liver disease has yet to be examined.

Aims

To study the function of the AhR in a model of cholestic liver disease. We will test the hypothesis that activation of AhR in the brain will reduce neuroinflammation and behavioral deficits observed in cholestatic mice.

Methods

Male C57Bl/6J mice had cholestasis induced by bile duct ligation (BDL); comparisons were made to sham-operated controls. Mice were tested for social interaction with a 4-week old juvenile in their home cage and the number of social interaction attempts quantified. Next, mice were euthanized, brains were removed and processed for immunohistochemistry. Brain sections were stained for markers of microglia (IBA-1) and astrocytes (GFAP). Microglia were counted and astrocyte activation was qualitatively assessed. PCR was used to quantify gene expression of AhR and its downstream gene targets (eg. CYP1A1) in mice that recived treatment with beta-napthoflavone (BNF), an AhR agonist, or in vehicle treated controls.

Results

BDL mice made significantly fewer attempts to interact with the juvenile as compared to controls (P&lt;0.05). We also observed a significant increase in IBA-1 immunoreactive cell numbers in both the CA1 region of the hippocampus and the hypothalamic paraventricular nucleus (PVN, P&lt;0.05). BDL mice also displayed marked increases in GFAP+ staining in the PVN, but not the CA1, in contrast to sham controls. Lastly, we found that BNF significantly upregulated CYP1A1 (P&lt;0.05) in the liver and prefrontal cortex of mice. We are currently examining whether BNF can reduce neuroinflammation and improve decreased social interaction in cholestatic mice.

Conclusions

Cholestatic liver damage was associated with impaired social behavior. Further, glial activation, an indicator of neuroinflammation was increased in components of the limbic system associated with the response to stress, learning, and memory. Future experiments will address whether activation of the AhR will ameliorate neuroinflammation and behavioral changes observed in mice with cholestatic liver injury.

Funding Agencies

CCC, CIHR

Left Ventricular Unloading Increases the Coronary Collateral Flow Index Before Reperfusion and Reduces Infarct Size in a Swine Model of Acute Myocardial Infarction

Background Unloading the left ventricle and delaying reperfusion reduces infarct size in preclinical models of acute myocardial infarction. We hypothesized that a potential explanation for this effect is that left ventricular (LV) unloading before reperfusion increases collateral blood flow to ischemic myocardium. Methods and Results Acute myocardial infarction was induced by balloon occlusion of the left anterior descending artery for 120 minutes in adult swine, followed by reperfusion for 180 minutes. After 90 minutes of occlusion, animals were assigned to 30 minutes of continued occlusion (n=6) or to 30 minutes of support with either an Impella CP (n=4) or venoarterial extracorporeal membrane oxygenation (n=5) with persistent occlusion. The primary end point was measures of microcirculatory blood flow including the collateral flow index (CFI) during left anterior descending artery occlusion as (P_w-RA)/(P_a-RA), where P_a, P_w, and RA are aortic, coronary wedge, and right atrial pressure, respectively. Infarct size was quantified using triphenyltetrazolium chloride. Compared with continued occlusion, Impella, not venoarterial extracorporeal membrane oxygenation, reduced infarct size relative to the area at risk. Before reperfusion, Impella reduced LV stroke work by 25% and increased the CFI by 75%, but venoarterial extracorporeal membrane oxygenation did not. Among all groups, the change in CFI between 90 and 120 minutes correlated inversely with the change in LV stroke work (r²=0.44, P=0.01) and infarct size (r²=0.41, P=0.02). Conclusions We report for the first time that 30 minutes of LV unloading during coronary occlusion increases the CFI, which correlates inversely with LV stroke work and infarct size. Venoarterial extracorporeal membrane oxygenation failed to increase the CFI and did not reduce infarct size.

Abstract 589: Left Ventricular Unloading and Delayed Coronary Reperfusion Protects the Structural and Functional Integrity of Mitochondrial Complex 1 in a Preclinical Model of Acute Myocardial Infarction

Background: Mitochondrial Complex 1 (MC1) plays a key role in energy metabolism during myocardial ischemia-reperfusion injury (M-IRI). Disruption of MC1 promotes reactive oxygen species (ROS) generation and myocardial damage. We recently reported that first reducing left ventricular (LV) workload using a trans-valvular pump and delaying coronary reperfusion, known as Primary Unloading (PU), reduces infarct size in preclinical models of M-IRI. The Door to Unload Pilot Trial recently demonstrated the safety and feasibility of PU in patients with ST-segment elevation myocardial infarction (STEMI), however the cardioprotective mechanisms of PU remain poorly understood. We hypothesized that compared to immediate reperfusion (IR); PU preserves mitochondrial function in M-IRI.

Results: M-IRI was induced by balloon occlusion of the left anterior descending artery for 120 minutes in adult swine followed by reperfusion for 180 minutes. After 90 minutes of occlusion, animals were assigned to 30 minutes of continued occlusion (IR, n=5) or 30 minutes of support with an Impella CP pump (PU, n=5) with persistent occlusion before reperfusion. Compared to IR, PU reduced LV stroke work by 38.4% (p=0.047) and infarct size by 41.3±5.6% (p=0.0052). Compared to IR, PU preserved gene and protein expression of specific MC1 subunits (NDUFA8 and NDUFS3). Using the Agilent Seahorse Platform, we identified that compared to IR, PU preserved function of MC1 and ATP production in mitochondria isolated from the infarct zone by 82.45±12.8% (p=0.0040, IR vs PU). Compared to IR, PU reduced levels of ROS and preserved mitochondrial membrane potential. Next, we studied the activation state of MC1 and observed that compared to IR alone, PU increased the ratio of activated A form versus de-activated D form from 2.79 ± 0.29 to 7.58 ± 0.80 (p=0.005) levels of MC1 within the infarct zone.

Conclusion: We report for the first time that compared to IR, mechanically unloading the LV and delaying reperfusion protects the structural and functional integrity of mitochondrial complex 1. These findings provide new insight into the cardioprotective mechanisms of Primary Unloading and support the development of novel therapeutic approaches to improve clinical outcome for patients with STEMI.

Abstract 586: VA-ECMO Increases Urinary Levels of the Biomarker Kidney Injury Marker-1 (KIM-1) in a Preclinical Model of Acute Myocardial Infarction

Background: Acute kidney injury (AKI) is associated with increased morbidity and mortality in patients with acute myocardial infarction (AMI). Use of trans-valvular pumps and veno-arterial extracorporeal membrane oxygenation (VA-ECMO) for patients with AMI is growing. Trans-valvular pumps transfer rotational kinetic energy to blood and generate flow from the left ventricle into the ascending aorta. VA-ECMO drains blood from the venous system and returns oxygenated blood into the descending aorta, thereby increasing systemic perfusion. The impact of these support strategies on renal blood flow and function remains poorly understood. We hypothesized that compared to a trans-valvular pump, VA-ECMO is associated with increased renal injury in AMI.

Methods and Results: Adult male swine were subjected to left anterior descending artery occlusion for 90 minutes followed by either immediate reperfusion (IRI), trans-valvular pumping (Impella CP) or VA-ECMO starting 30 minutes before reperfusion, or sham-operated controls (n=4/group). Compared to IRI, urinary levels of the biomarker kidney injury molecular 1 (KIM-1) were increased by VA-ECMO, not Impella. Inflammatory factors IL6 and IL1beta were increased by VA-ECMO, not Impella in both plasma and cortex tissue by ELISA analysis. KIM-1 protein expression for precursor KIM-1 and the extracellular domain (soluble) of KIM-1, as well as STAT3, HIF1alpha were analyzed by Western blot. Compared to sham, IRI and VA-ECMO reduced levels of soluble KIM-1 and increased levels of the KIM-1 protein precursor, pSTAT3 and HIF1a in the renal cortex. Impella had no impact on these protein levels.

Conclusion: This is first study to identify that VA-ECMO, not Impella, increases urinary levels of KIM-1 , a highly sensitive biomarker of acute kidney injury. The shedding of KIM-1 extracellular domain from the renal cortex is associated with systemic inflammatory response. These findings may identity novel approaches to limit renal injury in AMI patients requiring mechanical circulatory support.

Mechanical Left Ventricular Unloading to Reduce Infarct Size During Acute Myocardial Infarction: Insight from Preclinical and Clinical Studies

Acute myocardial infarction (AMI) remains a leading cause of morbidity and mortality. Pioneering preclinical work reported by Peter Maroko and Eugene Braunwald in 1971 identified oxygen supply and demand are primary determinants of myocardial infarct size in the setting of a heart attack. Since the 1950s, advances in mechanical engineering led to the development of short-term circulatory support devices that range from pulsatile to continuous flow pumps. The primary objective of these pumps is to reduce native heart work, enhance coronary blood flow, and sustain systemic perfusion. Whether these pumps could reduce myocardial infarct size in the setting of AMI became an intense focus for preclinical investigation with variable animal models, experimental algorithms, and pump platforms being tested. In this review, we discuss the design of these preclinical studies and the evolution of mechanical support platforms and attempt to translate these experimental methods into clinical trials.

Transgenic Organisms Meet Redox Bioimaging: One Step Closer to Physiology

SIGNIFICANCE

Redox signaling is a common mechanism in the cellular response toward a variety of stimuli. For analyzing redox-dependent specific alterations in a cell, genetically encoded biosensors were highly instrumental in the past. To advance the knowledge about the importance of this signaling mechanism in vivo, models that are as close as possible to physiology are needed. Recent Advances: The development of transgenic (tg) redox biosensor animal models has enhanced the knowledge of redox signaling under patho(physio)logical conditions. So far, commonly used small animal models, that is, Caenorhabditis elegans, Drosophila melanogaster, and Danio rerio, and genetically modified mice were employed for redox biosensor transgenesis. However, especially the available mouse models are still limited.

CRITICAL ISSUES

The analysis of redox biosensor responses in vivo at the tissue level, especially for internal organs, is hampered by the detection limit of the available redox biosensors and microscopy techniques. Recent technical developments such as redox histology and the analysis of cell-type-specific biosensor responses need to be further refined and followed up in a systematic manner.

FUTURE DIRECTIONS

The usage of tg animal models in the field of redox signaling has helped to answer open questions. Application of the already established models and consequent development of more defined tg models will enable this research area to define the role of redox signaling in (patho)physiology in further depth. Antioxid. Redox Signal. 29, 603-612.

Loss of PHD3 in myeloid cells dampens the inflammatory response and fibrosis after hind-limb ischemia

Macrophages are essential for the inflammatory response after an ischemic insult and thereby influence tissue recovery. For the oxygen sensing prolyl-4-hydroxylase domain enzyme (PHD) 2 a clear impact on the macrophage-mediated arteriogenic response after hind-limb ischemia has been demonstrated previously, which involves fine tuning a M2-like macrophage population. To analyze the role of PHD3 in macrophages, we performed hind-limb ischemia (ligation and excision of the femoral artery) in myeloid-specific PHD3 knockout mice (PHD3^−/−) and analyzed the inflammatory cell invasion, reperfusion recovery and fibrosis in the ischemic muscle post-surgery. In contrast to PHD2, reperfusion recovery and angiogenesis was unaltered in PHD3^−/− compared to WT mice. Macrophages from PHD3^−/− mice showed, however, a dampened inflammatory reaction in the affected skeletal muscle tissues compared to WT controls. This was associated with a decrease in fibrosis and an anti-inflammatory phenotype of the PHD3^−/− macrophages, as well as decreased expression of Cyp2s1 and increased PGE2-secretion, which could be mimicked by PHD3^−/− bone marrow-derived macrophages in serum starvation.

Redox Imaging Using Cardiac Myocyte-Specific Transgenic Biosensor Mice

RATIONALE

Changes in redox potentials of cardiac myocytes are linked to several cardiovascular diseases. Redox alterations are currently mostly described qualitatively using chemical sensors, which however do not allow quantifying redox potentials, lack specificity, and the possibility to analyze subcellular domains. Recent advances to quantitatively describe defined redox changes include the application of genetically encoded redox biosensors.

OBJECTIVE

Establishment of mouse models, which allow the quantification of the glutathione redox potential (E_GSH) in the cytoplasm and the mitochondrial matrix of isolated cardiac myocytes and in Langendorff-perfused hearts based on the use of the redox-sensitive green fluorescent protein 2, coupled to the glutaredoxin 1 (Grx1-roGFP2).

METHODS AND RESULTS

We generated transgenic mice with cardiac myocyte-restricted expression of Grx1-roGFP2 targeted either to the mitochondrial matrix or to the cytoplasm. The response of the roGFP2 toward H₂O₂, diamide, and dithiothreitol was titrated and used to determine the E_GSH in isolated cardiac myocytes and in Langendorff-perfused hearts. Distinct E_GSH were observed in the cytoplasm and the mitochondrial matrix. Stimulation of the cardiac myocytes with isoprenaline, angiotensin II, or exposure to hypoxia/reoxygenation additionally underscored that these compartments responded independently. A compartment-specific response was also observed 3 to 14 days after myocardial infarction.

CONCLUSIONS

We introduce redox biosensor mice as a new tool, which allows quantification of defined alterations of E_GSH in the cytoplasm and the mitochondrial matrix in cardiac myocytes and can be exploited to answer questions in basic and translational cardiovascular research.

Prolyl-4-hydroxylase domain 3 (PHD3) is a critical terminator for cell survival of macrophages under stress conditions

On a molecular level, cells sense changes in oxygen availability through the PHDs, which regulate the protein stability of the α-subunit of the transcription factor HIF. Especially, PHD3 has been additionally associated with apoptotic cell death. We hypothesized that PHD3 plays a role in cell-fate decisions in macrophages. Therefore, myeloid-specific PHD3(-/-) mice were created and analyzed. PHD3(-/-) BMDM showed no altered HIF-1α or HIF-2α stabilization or increased HIF target gene expression in normoxia or hypoxia. Macrophage M1 and M2 polarization was unchanged likewise. Compared with macrophages from WT littermates, PHD3(-/-) BMDM exhibited a significant reduction in TUNEL-positive cells after serum withdrawal or treatment with stauro and SNAP. Under the same conditions, PHD3(-/-) BMDM also showed less Annexin V staining, which is representative for membrane disruption, and indicated a reduced early apoptosis. In an unbiased transcriptome screen, we found that Angptl2 expression was reduced in PHD3(-/-) BMDM under stress conditions. Addition of rAngptl2 rescued the antiapoptotic phenotype, demonstrating that it is involved in the PHD3-mediated response toward apoptotic stimuli in macrophages.

Evaluation of a pharmacist-led, medicines education program for Aboriginal Health Workers

INTRODUCTION

The health of Indigenous Australians is exceptionally poor compared with that of non-Indigenous Australians. Cardiovascular diseases are the leading cause of death, the death rate being at least 2.7 times higher than the total Australian population. Indigenous Australians also experience underutilisation and reduced quality use of medicines. Aboriginal Health Workers (AHWs) are appropriate members of the healthcare team to provide information about medicines to the Indigenous community. However, despite having an expanding role in medicines management, AHWs have reported they do not have adequate appropriate education to support this role. Community pharmacists in localities with high Indigenous populations are well placed to provide medicines education to AHWs; however, to be successful in this role they need to develop their cultural awareness. The purpose of this study was to evaluate a culturally appropriate, pharmacist-led cardiovascular medicines education program for AHWs. Research questions included: What was the impact of the program on the pharmacists? What were the barriers and facilitators? Was the program useful and acceptable to the AHWs?

METHODS

Four educational units were developed in collaboration with AHWs. A purposive sample of community pharmacists from western New South Wales (NSW) attended training involving instruction in the delivery of the program and cultural awareness training. The pharmacists then recruited local AHWs and delivered the program. Evaluation, with respect to the pharmacists, involved a repeated measures, three-phase questionnaire and semi-structured, face-to-face, in-depth interview post-program. Feedback was obtained from the AHWs in the form of a brief survey, and an audit of the attendance at each session was performed.

RESULTS

Twelve pharmacists in 10 localities throughout western NSW delivered the program to a total of 47 AHWs. Statistically significant differences in the questionnaire responses, as a result of delivering the education, indicated the pharmacists felt better equipped to deal with Indigenous health issues (p = 0.002, Mann-Whitney U-test); they knew more AHWs in their area (p = 0.005, Mann-Whitney U-test); they felt more confident as educators of AHWs (p = 0.007, Mann-Whitney U-test); and more confident that they had the necessary resources to deliver this education (p = 0.005, Mann-Whitney U-test). The semi-structured interviews revealed that the experience of delivering the education improved pharmacists' confidence as educators and motivated them to develop sustainable relationships with AHWs. A significant barrier lay in the challenges associated with organizing the AHW education sessions, while an important facilitator was prior established relationships with local Aboriginal health services. Evaluation with respect to the AHWs revealed the program reached 80% (n = 47/59) of AHWs within the western NSW region. In total, 46% (n = 27) of AHW participants attended all four educational units and attendance at each educational unit was above 78% (n = 37) throughout. The AHWs reported that they found the program interesting and relevant and were enthusiastic for future collaboration with the pharmacists.

CONCLUSIONS

The desire to develop sustainable relationships was seen by all participants as the most positive aspect of the program.

The National Population Health Survey--its longitudinal nature

OBJECTIVES

This article discusses some of the benefits and challenges of data from a longitudinal panel as exemplified by the National Population Health Survey (NPHS).

DATA SOURCE

The NPHS collects both cross-sectional and longitudinal data from a sample of randomly selected individuals. The longitudinal sample will be reinterviewed every 2 years for up to 20 years. Two NPHS cycles have been completed: cycle 1 in 1994/95 and cycle 2 in 1996/97.

SUMMARY

Selected findings from the NPHS are presented to illustrate the benefits of longitudinal data. An overview of questionnaire content, collection methods follows, and sample design is provided. A summary of response rates is followed by a discussion of the methods used to maintain response and to adjust the survey weights in order to reduce nonresponse bias. Confidentiality, dissemination, inconsistencies in reporting, proxy reporting and changes in coding conventions are also discussed.

Lectin from Codium fragile ssp. tomentosoides conjugated to colloidal gold: a new histochemical reagent

A new histochemical reagent has been developed utilising a lectin from a marine alga for the first time. Colloidal gold was coupled to the N-acetyl-alpha-D-galactosamine specific lectin from the green alga Codium fragile ssp. tomentosoides. The lectin--gold conjugate bound to the membranes of blood-group A1 human erythrocytes which were used as a model system. The bound complex could be detected, readily, by transmission electron microscopy. This novel reagent incorporating a lectin of low molecular weight (15 kDa) has potential value for studies of cell-surface topography of a variety of tissues.

Production of 1,25-dihydroxyvitamin D3 and 24,25-dihydroxyvitamin D3 by growth zone and resting zone chondrocytes is dependent on cell maturation and is regulated by hormones and growth factors

1,25-Dihydroxyvitamin D3 [1,25-(OH)2D3] and 24,25-(OH)2D3 have been shown to promote chondrocyte proliferation and differentiation; resting zone chondrocytes respond primarily to 24,25-(OH)2D3, whereas growth zone chondrocytes respond primarily to 1,25-(OH)2D3. This study determined whether resting zone and growth zone cells produce 24,25-(OH)2D3 or 1,25-(OH)2D3; whether this production is regulated by 1,25-(OH)2D3 (10(-8) M), 24,25-(OH)2D3 (10(-7) M), dexamethasone (10(-7) M), or recombinant human transforming growth factor-beta 1 (11 ng/ml); and whether the metabolites produced are biologically active. Confluent fourth passage rat costochondral growth zone or resting zone chondrocytes were cultured in Dulbecco's Modified Eagle's Medium containing [3H]25-hydroxyvitamin D3 ([3H]25OHD3), 2% fetal bovine serum, and antibiotics. Metabolism of [3H]25OHD3 was measured by analyzing the lipid extracts of the conditioned medium and the cell layer for [3H]1,25OHD3, [3H]1,25-(OH)2D3, and [3H]24,25-(OH)2D3 using flow-through scintillation spectroscopy of HPLC eluates. Chemically synthesized radioinert vitamin D3 metabolites were used as standards, and their migration was determined by absorbance at 254 nm. To ensure that the radioactive peaks were 1,25-(OH)2D3 and 24,25-(OH)2D3, the fractions were rechromatographed into three other HPLC solvent systems. Biological activity was confirmed; the addition of HPLC-purified 1,25-(OH)2D3 produced by growth zone chondrocytes elicited a dose-dependent stimulation of alkaline phosphatase specific activity in growth zone cell cultures, but had no effect on the resting zone cells. There was a time-dependent increase in both [3H]1,25-(OH)2D3 and [3H]24,25-(OH)2D3 in the conditioned medium of both types of cultures. At 24 h, the percent conversion of [3H]25OHD3 to [3H]1,25-(OH)2D3 was 5.3 +/- 1.2, and the percent conversion to [3H]24,25-(OH)2D3 was 1.8 +/- 0.4 in growth zone chondrocyte cultures. No such effect was found in cultures freeze-thawed five times or without cells. When resting zone cells were cultured with [3H]25OHD3, the percent conversion to 1,25-(OH)2D3 and 24,25-(OH)2D3 was 4.5 +/- 1.0 and 1.7 +/- 0.4, respectively. The addition of dexamethasone significantly increased the percent production of 1,25-(OH)2D3 at 6 and 24 h and at 6 h by resting zone and growth zone cells, respectively, compared to the control values. Recombinant human transforming growth factor-beta 1 increased the percent production of 1,25-(OH)2D3 after 1 h in resting zone cells and, after 24 h, the production of 24,25-(OH)2D3 in growth zone cells. Radiolabeled 1,25-(OH)2D3 and 24,25-(OH)2D3 were not detected in the cell layer.(ABSTRACT TRUNCATED AT 400 WORDS)

In vivo regulation of matrix vesicle concentration and enzyme activity during primary bone formation

In vivo regulation of matrix vesicles (MV) during primary bone formation was examined using tibial marrow ablation in rats as the experimental model. The effects of bone-bonding and nonbonding implants on the number of MV/micron 2 of matrix and the alkaline phosphatase (ALPase) and phospholipase A2 (PA2) activities of MV-enriched microsomes (MVEM) isolated from the healing bone were studied. MV concentration, ALPase, and PA2 were increased by bone-bonding implants by day 3 post-surgery; a similar effect was seen in the contralateral limb, but at a lower magnitude. Nonbonding implants had no effect at day 3 and decreased MV concentration and PA2 activity at later time points; the same behavior was observed in the contralateral limb. These results demonstrate that MVs are influenced in a differential manner by implant materials, both locally and systemically, and can be regulated during primary mineralization.

Differential regulation of prostaglandin E2 synthesis and phospholipase A2 activity by 1,25-(OH)2D3 in three osteoblast-like cell lines (MC-3T3-E1, ROS 17/2.8, and MG-63)

Both 1,25-(OH)2D3 and prostaglandin E2 (PGE2) stimulate alkaline phosphatase activity in MC-3T3-E1 cells. Previous studies, demonstrating a correlation between 1,25-(OH)2D3-dependent alkaline phosphatase and phospholipase A2 activities in matrix vesicles isolated from growth cartilage chondrocyte cultures, suggest that one mechanism of vitamin D action may be via autocrine or paracrine action of PGE2. Since most PGE2 is derived from arachidonic acid released by the action of phospholipase A2, we examined whether 1,25-(OH)2D3 stimulates phospholipase A2 activity in three osteoblastic cell lines: ROS 17/2.8 cells, MC-3T3-E1 cells, and MG-63 cells. 1,25-(OH)2D3-dependent alkaline phosphatase and phospholipase A2 activity were correlated with production of PGE2 and PGE1 in the MC-3T3-E1 cells. Alkaline phosphatase specific activity was enriched in the matrix vesicles produced by all three cell types and was stimulated by 1,25-(OH)2D3 at 10(-8) to 10(-7) M. Although phospholipase A2 specific activity was enriched in the matrix vesicles produced only by the ROS 17/2.8 cell cultures, stimulation of this enzyme activity was observed only in the MC-3T3-E1 cell cultures. The effects of 1,25-(OH)2D3 on phospholipase A2 were dose-dependent and were significant at 10(-8) to 10(-7) M. There was a significant increase in PGE2 production in the MC-3T3-E1 cell cultures only. Indomethacin reduced PGE2 production to base line values. Even at baseline, MC-3T3-E1 cells produced ten times more PGE2 than did the ROS 17/2.8 or MG-63 cell cultures. The effects of 1,25-(OH)2D3 on PGE1 were comparable to those on PGE2.(ABSTRACT TRUNCATED AT 250 WORDS)

Characterization of benzo[a]pyrene metabolites formed by 3-methylcholanthrene-induced goldfish, black bullhead and brown bullhead

Metabolites of BaP formed by 3-MC-induced goldfish (Carassius auratus), black bullhead (Ictalurus melas), brown bullhead (Ictalurus nebulus) and rat have been separated by HPLC. The main metabolites in both bullhead species and the rat were 3-hydroxy-BaP and BaP 9,10- and 7,8-dihydrodiols, whereas BaP 1,6- and 3,6-diones and 9- and 3-hydroxy-BaP predominated in the goldfish. Induced rat formed over 10 times as many total metabolites as the fish. No induction was observed in the 3-MC-treated brown bullheads kept at 7 degrees C. TCPO and alpha-naphthoflavone decreased metabolite production by 50 and 30%, respectively.