The decrease in population bone lead levels in Canada between 1993 and 2010 as assessed by in vivo XRF.

Objective and Approach: A study, conducted in Toronto, Canada, between 2009 and 2011, measured the bone lead concentrations of volunteers aged 1-82 years using in vivo x-ray fluorescence (XRF) technology. MAIN RESULTS: Bone lead levels were lower compared to Ontario in vivo XRF studies from the early 1990s. In adults, the slope of tibia lead content versus age was reduced by 36-56%, i.e. bone lead levels for a given age group were approximately half compared to the same age group 17 years prior. Further, bone lead levels of individuals fell over that time period. In 2010, an average person aged 57 years had a bone lead level approximately 1/3 less than their bone lead level age 40 years in 1993. Using this data, the half-lives of lead in the tibia were estimated as 7-26 years. Tibia lead levels were found to be low in children. The reduction in bone tibia content in children was not significant (p = 0.07), but using data from additional north eastern US studies, there is evidence that childhood tibia stores are lower than in the 1990s. SIGNIFICANCE: In vivo XRF analysis shows that there has been a reduction in the level of lead in bone in Canada over the last two decades. Public health measures have been very successful in reducing ongoing exposure to lead and in reducing bone lead stores.

Age and sex influence on bone and blood lead concentrations in a cohort of the general population living in Toronto.

OBJECTIVE: To study the age and sex influence on bone and blood lead concentrations in a cohort of the general population living in Toronto. APPROACH: A 109Cd K x-ray fluorescence (KXRF) measurement system was used from 2009 to 2011 in a study that measured the bone lead (Pb) concentration of 263 environmentally exposed individuals residing in Toronto, Ontario, Canada. Tibia (cortical bone) and calcaneus (trabecular bone) lead contents were measured in 134 males and 129 females between 1 and 82 years of age. Whole blood Pb concentration was measured by TIMS (thermal ionization mass spectrometer). Tibia (Ti) and calcaneus (Cal) Pb were examined versus the age of participants, taking into account uncertainties in bone Pb measurement values. MAIN RESULTS: No significant sex differences were observed in any of the age categories. Participants older than 50 years of age demonstrated the highest concentrations of Pb in their blood, tibia, and calcaneus bones. SIGNIFICANCE: In most of the previous publications, uncertainty was not considered in the regression model of bone Pb and age. However, in this paper, we adjusted the bone Pb values for the uncertainty level. This had a significant influence in regression models of bone Pb and thus we recommend that uncertainty be considered in future studies.

Effects of centrifugal and roller pumps on survival of autologous red cells in cardiopulmonary bypass surgery.

BACKGROUND: Either a roller pump or a centrifugal pump can be used in the extracorporeal circuit during surgery with cardiopulmonary bypass. In this study, we assessed the effect of these two pumps on the 24-h post-transfusion survival values of autologous red blood cells (RBC). STUDY DESIGN AND METHODS: Fourteen male patients subjected to extracorporeal bypass procedures were studied. In seven patients, the autologous red cells were collected following the cardiopulmonary bypass procedure using the roller pump, and in seven patients, autologous red cells were collected following the cardiopulmonary procedure using the centrifugal pump. The 24-h post-transfusion survival values of the autologous RBC were measured using the 51 disodium chromate/99m technetium double isotope procedure. The effects of the extracorporeal bypass procedures using the roller pump and the centrifugal pump were also assessed by the measurements of hematocrit, platelet count, plasma hemoglobin, and serum lactate dehydrogenase levels. RESULTS: The 51 disodium chromate 24-h post-transfusion survival values of the autologous RBC were similar whether the roller pump or the centrifugal pump was used in the extracorporeal circulation, as were the hematocrit, platelet count, plasma hemoglobin and serum lactate dehydrogenase levels. CONCLUSION: The 24-h post-transfusion survival values of autologous RBC, measured by the 51 disodium chromate/99m technetium double isotope procedure, were not significantly different, whether the roller pump or the centrifugal pump was used in the extracorporeal circuit using membrane oxygenators during cardiopulmonary surgical procedures.

Contaminant risks from biosolids land application: contemporary organic contaminant levels in digested sewage sludge from five treatment plants in Greater Vancouver, British Columbia.

This study examines the potential for environmental risks due to organic contaminants at sewage sludge application sites, and documents metals and various potential organic contaminants (volatile organics, chlorinated pesticides, PCBs, dioxins/furans, extractable petroleum hydrocarbons, PAHs, phenols, and others) in current production biosolids from five wastewater treatment plants (WWTPs) within the Greater Vancouver Regional District (GVRD). There has been greater focus in Europe, North America and elsewhere on metals accumulation in biosolids-amended soil than on organic substances, with the exception of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans. Another objective, therefore, was to evaluate the extent to which management of biosolids re-use based on metal/metalloid levels coincidentally minimizes environmental risks from organic contaminants. Historical-use contaminants such as chlorophenols, PCBs, and chlorinated pesticides were not detected at environmentally relevant concentrations in any of the 36 fresh biosolids samples, and appear to have virtually eliminated from sanitary collection system inputs. The few organic contaminants found in freshly produced biosolids samples that exhibited high concentrations relative to British Columbia and Canadian soil quality benchmarks included p-cresol, phenol, phenanthrene, pyrene, naphthalene, and heavy extractable petroleum hydrocarbons (HEPHs--nCl9-C34 effective carbon chain length). It was concluded that, with the exception of these petroleum hydrocarbon constituents or their microbial metabolites, the mixing of biosolids with uncontaminated soils during land application and based on the known metal concentrations in biosolids from the Greater Vancouver WWTPs investigated provides adequate protection against the environmental risks associated with organic substances such as dioxins and furans, phthalate esters, or volatile organics. Unlike many other organic contaminants, the concentrations of petroleum hydrocarbon derived substances in biosolids has not decreased within the last decade or more in the WWTPs studied, and--unlike persistent chlorinated compounds--the associated PAHs and other hydrocarbon constituents merit careful consideration, especially in the context of repeated land-application of biosolid.

Role of myocardial temperature measurement in monitoring the adequacy of myocardial protection during cardiac surgery.

Inadequate myocardial protection continues to be encountered despite improved methods of cardioplegia delivery. Although myocardial temperature is commonly monitored to assess the adequacy of cardioplegia delivery, its relationship to the metabolic status of the myocardium has not been investigated. We prospectively reviewed patients who underwent valvular heart surgery with blood (n = 47) or crystalloid (n = 48) cardioplegia and continuous measurement of intraoperative myocardial tissue pH and temperature. We previously demonstrated a high correlation (r = 0.99) between extracellular myocardial pH, levels of intracellular hydrogen ion concentration, and a lowering of tissue ATP during coronary occlusion. Clinically, optimal metabolic protection was defined as the absence of myocardial tissue acidosis during the period of aortic occlusion as quantified by a temperature-corrected integrated mean pH of 6.8 or greater, which has been shown to be predictive of a favorable postoperative outcome. Age, bypass time, myocardial temperature, myocardial tissue pH at the onset of aortic occlusion, cross-clamp time, and volume of cardioplegia were not significantly different between blood and crystalloid groups. Linear regression analysis demonstrated no significant correlation between mean myocardial tissue pH and the corresponding mean myocardial temperature in either group during aortic occlusion. There was also no correlation between the mean myocardial tissue pH and volume of cardioplegia delivered in both groups. These data demonstrate wide intercardiac and intracardiac variability in the degree of regional tissue acidosis encountered during of hypothermic cardioplegia. Cardioplegia delivery guided by measurement of myocardial temperature or by standardized protocol did not prevent the occurrence of tissue acidosis and thus, did not ensure optimal metabolic protection of the heart. In 95 patients undergoing valvular heart surgery with cold blood or crystalloid cardioplegia, there was no correlation between myocardial tissue pH and mycardial temperature or between myocardial tissue pH and volume of cardioplegia administered. Temperature is a poor indicator of the metabolic state of the myocardium.

Comparison of the effects of transfusions of cryopreserved and liquid-preserved platelets on hemostasis and blood loss after cardiopulmonary bypass.

OBJECTIVE: The aim of the study was to compare the clinical effects and hemostatic efficiency of transfusions of platelets preserved in the frozen state for as long as 2 years with transfusions of platelets preserved in the conventional manner for as long as 5 days in patients undergoing cardiopulmonary bypass. METHODS: Seventy-three patients were prospectively randomly assigned to receive transfusions of cryopreserved or liquid-preserved platelets. Nonsurgical blood loss was measured during and after the operation. Bleeding time, hematologic variables, and the bleeding time site shed blood were assayed before cardiopulmonary bypass and at 30 minutes and 2, 4, and 24 hours after transfusion. In vitro platelet function tests were conducted on platelets obtained from healthy volunteers. RESULTS: No adverse sequelae of the transfusions were observed. Blood loss and the need for postoperative blood product transfusions were lower in the group receiving cryopreserved platelets. Lower posttransfusion platelet increments and a tendency toward decreased platelet survival were observed in patients receiving cryopreserved platelets. Hematocrit and plasma fibrinogen were significantly higher in this group, and the duration of intubation was shorter. In vitro, cryopreserved platelets demonstrated less aggregation, lower pH, and decreased response to hypotonic stress but generated more procoagulant activity and thromboxane. CONCLUSIONS: (1) Cryopreserved platelet transfusions are superior to liquid-preserved platelets in reducing blood loss and the need for blood product transfusions after cardiopulmonary bypass. (2) The reduction in blood loss in the patients receiving cryopreserved platelet transfusions after cardiopulmonary bypass probably reflects improved in vivo hemostatic function of cryopreserved platelets. (3) Some in vitro measures of platelet quality (aggregation, pH, hypotonic stress) may not reflect in vivo quality of platelet transfusions after cardiopulmonary bypass, whereas other in vitro measures (platelet procoagulant activity and thromboxane) do.

Continuous perfusion of donor hearts in the beating state extends preservation time and improves recovery of function.

OBJECTIVES: Improving methods of donor heart preservation may permit prolonged storage and remote procurement of cardiac allografts. We hypothesized that continuous, sanguineous perfusion of the donor heart in the beating, working state may prolong myocardial preservation. METHODS: We developed a portable perfusion apparatus for use in donor heart preservation. Contractile, metabolic, and vasomotor functions were monitored simultaneously in an isolated swine heart. The metabolic state was monitored by myocardial tissue pH. Vasomotor function was assessed in isolated coronary ring chambers. Hearts were randomized into 3 groups: group I (n = 5), cardioplegic arrest, 12-hour storage at 4 degrees C with modified Belzer solution, and 2-hour sanguineous reperfusion in the working state; group II (n = 6), 12-hour continuous perfusion in the beating working state, 30 minutes of arrest (to simulate re-implantation time), and 2 hours of reperfusion, as above; group III (n = 7), coronary ring control hearts. RESULTS: At 2 hours of reperfusion, left ventricular developed pressure in group II was higher than in group I (mean +/- standard deviation: 90 +/- 6 mm Hg, 53 +/- 15 mm Hg, P = .005). Significantly less myocardial edema was observed in group II than in group I (73% +/- 4%, 80% +/- 1% water content, P = .01). Significantly less myocardial acidosis was noted in group II than in group I during preservation (pH 7.3 +/- 0.01, 6.1 +/- 0.03, P < .001) and reperfusion (pH 7.3 +/- 0.008, 6.8 +/- 0.05, P < .001). Coronary endothelial vasomotor function was better preserved in group II than in group I as evidenced by dose-response relaxation of coronary rings to 10(-8) mol/L bradykinin (37%, 55% delta baseline, P = .01). CONCLUSION: This new method extends the current preservation limit and avoids time-dependent ischemic injury, thereby allowing for distant procurement of donor organs.

Heparin causes platelet dysfunction and induces fibrinolysis before cardiopulmonary bypass.

BACKGROUND: Platelet dysfunction and increased fibrinolysis are the most important etiologic factors in the hemostatic defect observed following the institution of cardiopulmonary bypass. This study examined the effects of heparin per se, administered before the institution of cardiopulmonary bypass, on platelet function and fibrinolysis. METHODS: Sampling was performed in 55 patients undergoing cardiac operations before and 5 minutes after the routine administration of heparin, before the institution of cardiopulmonary bypass. RESULTS: Heparin administration resulted in a significant prolongation of the bleeding time (from 6.3 +/- 2.1 to 12.6 +/- 4.9 minutes; p < 0.00001), a significant reduction in the level of shed blood thromboxane B2 (from 1,152 +/- 669 to 538 +/- 187 pg/0.1 mL; p = 0.00002), and an increase in the plasma levels of plasmin (from 11.8 +/- 9.7 to 125.4 +/- 34.8 U/L; p < 0.0001) and D-dimer (from 571.3 +/- 297.1 to 698.5 +/- 358.6 micrograms/mL; p = 0.05). There were no significant differences before and after heparin administration in the plasma levels of fibrinogen, plasminogen, tissue plasminogen activator, antiplasmin, antithrombin III, and von Willebrand factor. CONCLUSIONS: Heparin, independent of cardiopulmonary bypass, causes both platelet dysfunction and increased fibrinolysis. The use of an alternative anticoagulant or a lower dose of heparin in conjunction with heparin-coated surfaces might improve the hemostatic balance during open heart operations.

Intraoperative assessment of the stunned versus infarcted myocardium with the simultaneous use of transesophageal echocardiography and the measurement of myocardial pH: two case studies.

The ability to differentiate intraoperatively between myocardial stunning, which is reversible, and irreversible myocardial infarction has major implications because it provides a rational approach to the use or withholding of ventricular assist devices in patients with severe postcardiotomy ventricular dysfunction. Two illustrative cases are presented.

Metabolic correlates of myocardial stunning and the effect of cardiopulmonary bypass.

In order to study the metabolic consequences of myocardial stunning, repeated coronary occlusions were performed in dogs. The production of CO2, adenosine triphosphate (ATP), phosphocreatine (PCr), and inorganic phosphate (Pi) by myocardial cells was assessed, along with extracellular and intracellular pH. Our results indicate that regional coronary artery occlusion reduces the ability of the myocardium to produce H+ and CO2 and to replenish ATP post ischemia. These alterations, then, represent the hallmark of metabolic viability during periods of ischemic insult. Decreases in PCr and Pi were completely eliminated during reperfusion and, therefore, are ot reflective of myocardial stunning. When normothermic cardiopulmonary bypass (CPB) is instituted and the coronary artery is occluded three times with reperfusion between each occlusion, alterations in myocardial H+ and high energy phosphates are identical to those observed using only repetitive coronary occlusion. Systemic hypothermia during CPB does not protect against myocardial stunning; however, it is anticipated that interventions that prevent the reduction in H+ and ATP levels may overcome the effects of myocardial stunning that occur during cardiac surgery.

Oxygen cost of stress development in hypertrophied and failing hearts from the spontaneously hypertensive rat.

Left ventricular isovolumic stress development and metabolic parameters were studied in 18-24-month-old spontaneously hypertensive rats (SHRs) and age-matched Wistar-Kyoto (WKY) rat controls using the isolated, isovolumic (balloon in left ventricle) buffer-perfused rat heart preparation. After WKY rats and all SHRs were compared, SHRs were divided into two groups: those animals with (SHR-F) and without (SHR-NF) evidence of heart failure. Hearts were perfused at 100 mm Hg using a constant pressure system at a temperature of 37 degrees C. In the baseline state, peak systolic pressure was greatest in the SHR-NF group and lowest in the SHR-F group. Peak midwall stress was greatest in the WKY group and, again, lowest in the SHR-F group. Oxygen consumption was lowest in the SHR-F group. When the oxygen cost of stress development was estimated by normalizing myocardial oxygen consumption by peak developed midwall stress, values were lowest in the WKY, greater in the SHR-NF, and greatest in the SHR-F group. Lactate production did not occur in the baseline state in any of the groups. Functional and metabolic responses to graded hypoxia, induced by changing the gas mixture of the perfusate from 95% to 50%, 25%, and 0% oxygen at perfusion pressures of 100 and 130 mm Hg, were studied. Increasing perfusion pressure generally resulted in small increases in peak systolic pressure and myocardial oxygen consumption but did not substantially reverse the contractile or metabolic deficit present in the SHR-F group.(ABSTRACT TRUNCATED AT 250 WORDS)

Myocardial glutathione depletion impairs recovery after short periods of ischemia.

Isolated, isovolumic rat hearts, perfused by Krebs-Henseleit buffer at constant coronary flow rate, were used to explore the hypothesis that endogenous cardiac glutathione provides protection against myocardial dysfunction associated with short periods of ischemia. Experimental animals were depleted of cardiac glutathione to 35% of control levels by intraperitoneal injections of diethylmaleate (DEM). Left ventricular pressure, coronary perfusion pressure, and glutathione levels were measured in control and experimental hearts after 60 minutes of oxygenated perfusion and after 20 minutes of global, no-flow ischemia and 30 minutes of reperfusion. With each protocol, both control and glutathione-depleted hearts received either standard buffer or one supplemented with 2 mM glutathione. Recovery of systolic function after ischemia-reperfusion was impaired in DEM-treated hearts compared with controls. In addition, the rise in perfusion pressure and chamber stiffness was also greater in DEM-treated hearts compared with controls. Recovery in glutathione-depleted hearts was improved when the reperfusate was supplemented with glutathione. In addition, the supplemented reperfusate prevented the decrease in compliance and the increase in coronary perfusion pressure in the glutathione-depleted hearts. Ischemia-reperfusion alone were not associated with a significant alteration in myocardial glutathione levels. Prewashout myocardial levels of glutathione were elevated after reperfusion with glutathione-supplemented buffer but fell to baseline levels after a short washout period. These studies demonstrate that endogenous glutathione is important in protection of myocardium from injury after ischemia-reperfusion, presumably by modifying levels of active oxygen intermediates. The smaller changes in left ventricular pressure and coronary resistance after administration of GSH probably reflects an extracellular mechanism because benefit is seen soon after reperfusion.

A microangiographic study of hematoma-associated flap necrosis and salvage with isoxsuprine.

Rat dorsal skin flaps predictably underwent full-thickness necrosis by 48 hours when hematoma had been placed beneath the flap. Microangiographic studies demonstrated failure of filling of the distal vasculature of these flaps. This was in marked contrast to the complete reestablishment of circulation in control flaps, overlying equal volumes of serum. The circulation of failing flaps overlying hematoma was restored with isoxsuprine given parenterally 1 hour preoperatively and every 4 hours for 24 hours postoperatively. This pharmacologic regimen gave consistent reestablishment of flap perfusion and flap survival. The toxic component of hematoma acts on the circulation to a skin flap. This may be at the same level of the vasculature as the vasodilating action of isoxsuprine.

Povidone-iodine and tensile strength of wounds in rats.

The present study was designed to test the hypothesis that povidone-iodine would inhibit the recovery of tensile strength in a healing wound. Clean, incised dorsal wounds in rats were soaked in 1% povidone-iodine solution for 15 minutes; control wounds were soaked in lactated Ringer's solution before closure. Tensile strength measurements and histologic studies were conducted at 1, 2, and 6 weeks. No statistical differences in the rate of gain of tensile strength or histological appearance were noted between control and experimental wounds. It is concluded that brief irrigation of clean incised wounds with povidone-iodine solution does not affect factors important in the recovery of tensile strength during would healing, such as fibroplasia and collagen cross-linking.