Monitoring rainwater and seaweed reveals the presence of (131)I in southwest and central British Columbia, Canada following the Fukushima nuclear accident in Japan.

Detailed analysis of (131)I levels in rainwater and in three species of seaweed (Fucus distichus Linnaeus, Macrocystis pyrifera, and Pyropia fallax) collected in southwest British Columbia and Bella Bella, B.C., Canada was performed using gamma-ray spectroscopy following the Fukushima nuclear power plant accident on March 11, 2011. Maximum (131)I activity was found to be 5.8(7) Bq/L in rainwater collected at the campus of Simon Fraser University in Burnaby, B.C. nine days after the accident. Concomitantly, maximum observed activity in the brown seaweed F. distichus Linnaeus was observed to be 130(7) Bq/kg dry weight in samples collected in North Vancouver 11 days following the accident and 67(6) Bq/kg dry weight in samples collected from the Bamfield Marine Sciences Centre on Vancouver Island 17 days following the accident. The (131)I activity in seaweed samples collected in southwest B.C. following the Fukushima accident was an order of magnitude less than what was observed following Chernobyl. Iodine-131 activity in F. distichus Linnaeus remained detectable for 60 days following the accident and was detectable in each seaweed species collected. The Germanium Detector for Elemental Analysis and Radioactivity Studies (GEARS) was modeled using the Geant4 software package and developed as an analytical tool by the Nuclear Science group in the Simon Fraser University Department of Chemistry for the purpose of these measurements.

Psychological correlates of vasectomy.

OBJECTIVE: To examine the thoughts and concerns of men contemplating vasectomy before speaking to a physician as well as their partner's role in reaching this decision. DESIGN: A questionnaire analysis using response rates, ANOVA, and regression analyses. SETTING: A large Midwestern teaching hospital. PATIENT(S): Visitors to the urology clinic of the hospital. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): [1] Questionnaire designed by authors. [2] Measures of self-concept, relationship satisfaction, and problem-solving abilities. RESULT(S): [1] Subjects had been considering vasectomy for an average of 1 year and were fairly certain of their decision. [2] Anxiety about vasectomy surgery was mostly driven by fear about pain and fear of the unknown. [3] Concerns about the finality of the procedure did not emerge as a big concern. [4] There is confusion about the reversibility of the procedure. [5] Subjects are better problem solvers and have a higher self-concept than people in general. CONCLUSION(S): Our findings demonstrate the need for adequate prevasectomy counseling, particularly in the area of postoperative expectations, as well as reversibility of the procedure.

Heavy metal music and adolescent suicidality: an empirical investigation.

This study investigated the relationship between preference for heavy metal music and vulnerability to suicide among 121 high school students. Heavy metal fans had less strong reasons for living (especially male fans) and had more thoughts of suicide (especially female fans). For a large majority, listening to music (all types) had a positive effect on mood. Overall, the results indicate that preference for heavy metal music among adolescents may be a "red flag" for increased suicidal vulnerability, but also suggest that the source of the problem may lie more in personal and familial characteristics than in any direct effects of the music. Implications for intervention and for future research are discussed.

Employee assistance programs: a worldwide perspective.

Once limited to U.S. corporations, employee assistance programs (EAPs) are now spreading around the world. The authors review global EAP trends and identify similarities and differences among EAPs in North America, Europe, Central and South America, the Asia-Pacific region, and the Caribbean. Through affiliations between international professional associations and services to multinational corporations, the EAP field is quietly creating globalized behavioral health services.

Modulation of coronary flow by left ventricular volume in the presence and absence of vasomotor tone.

This study was undertaken to determine the relationship between left ventricular (LV) volume and coronary flow in the presence and absence of coronary vasomotor tone in arrested dog hearts. We utilized an isolated, blood-perfused, potassium-arrested dog heart preparation with vascular vasomotor tone present (n = 5) or after maximal vasodilation with adenosine (n = 7). LV volume was controlled with a balloon while left and right coronary flows were recorded. Left and right coronary flows were plotted as a function of LV volume, and the degree of interdependency was quantitatively assessed by the slope of the linear regression and the correlation coefficient (r) between coronary flow and LV volume. With vasomotor tone present, both left (slope = 0.01 +/- 0.06 min-1) and right (slope = -0.01 +/- 0.01 min-1) coronary arterial flows were maintained relatively constant over a wide range of LV volumes. After maximal vasodilation, left coronary flow decreased linearly with LV volume loading (slope = -2.51 +/- 0.47 min-1, r2 = 0.96 +/- 0.02), whereas right coronary flow, similar to the response with tone present, did not change relative to control in most cases. We conclude that changes in coronary vasomotor tone may take place with LV volume loading to compensate for the mechanical vascular resistance changes secondary to myocardial stretch.

Left ventricular mechanics in arrested dog heart: effects of ventricular interaction and vascular volumes.

The present study was designed to determine the effects of right heart pressure on the compliance of the left ventricle (LV). The studies were conducted on isolated, blood-perfused, potassium-arrested dog hearts with vasomotor tone either present (n = 5) or absent (n = 8). A balloon was used to control LV volume, whereas right heart (RHP) or coronary sinus (CSP) pressures were controlled via a column placed in the right heart or coronary sinus, respectively. Control of CSP independently of RHP allowed us to assess the relative contribution of coronary venous pressure to changes in LV compliance under conditions of elevated RHP. LV volume and compliance at a LV pressure of 15 mmHg (V15 and C15, respectively) were calculated to quantify the shift and slope changes of the LV pressure-volume (P-V) relationships. V15 and C15 decreased with vasomotor tone present from 52.8 +/- 1.4 ml and 1.7 +/- 0.1 ml/mmHg at control, to 43.3 +/- 2.1 ml and 1.4 +/- 0.1 ml/mmHg (P < 0.05) with RHP = 0 and 20 mmHg, respectively. Similar effects were obtained with vasodilation, but C15 was significantly lower relative to autoregulation but C15 was significantly lower relative to autoregulation (1.0 +/- 0.1 at control RHP, P < 0.05). Elevation of CSP with vasomotor tone resulted in an upward shift in the LV P-V relationship: V15 decreased from 53.4 +/- 2.1 at CSP = 0 mmHg to 50.9 +/- 1.6 ml at CSP = 20 mmHg (P < 0.05). After vasodilation there was no detectable shift in the LV P-V relationship with elevation of CSP.

Reduced collateral perfusion is a direct consequence of elevated right atrial pressure.

In the present study we determined quantitatively the effects of increased right atrial pressure (RAP) on coronary and collateral flows. In an isolated, blood-perfused, maximally vasodilated dog heart preparation in which the left ventricle was vented, we used the retrograde flow method to assess collateral flow. When RAP was elevated from 5 +/- 1 (control) to 13 +/- 1 and 23 +/- 1 mmHg, retrograde flow from the left circumflex coronary artery (which was open to atmospheric pressure) increased 29 +/- 8 and 97 +/- 21% relative to control while left anterior descending flow decreased 5 +/- 1 and 14 +/- 2%, respectively (P < 0.01; n = 7). The increase in retrograde flow could be due to 1) an increase in collateral flow due to increased pressure at the origin of the collaterals or 2) the elevated RAP (venous outflow pressure), which forces the antegrade collateral flow component in the retrograde direction. To distinguish between these possibilities we embolized the circumflex with 30-microns spheres to eliminate the antegrade flow component. After embolization there was no significant change in retrograde flow with elevated RAP, indicating that the second supposition was correct. We conclude that increased RAP 1) results in a reduction of flow to the collateral-dependent myocardium and 2) reduces perfusion of the unoccluded coronary vessel. Furthermore, we found that under conditions of varying venous outflow pressure, retrograde flow may not serve as a reliable index of collateral flow.

Pressure-flow characteristics of intramural and total coronary collateral networks.

The purpose of the present investigation was to determine the pressure-flow (PF) relationship of intramural collaterals and to determine whether their characteristics differ significantly from those of the total collateral network, defined as the epicardial plus intramural collateral network. Because a significant portion of the collateral flow is diverted away from the retrograde flow measurement, we embolized the coronary vessel on which the retrograde flow was measured with spheres of various sizes until the retrograde flow was maximized and retrograde flow diversion blocked. The PF relationship was obtained before and after the epicardial collaterals were cauterized to determine the characteristics of the total and intramural collateral network. PF data for the collateral circulations were obtained by changing the inflow pressure to all coronary vessels simultaneously and by measuring the retrograde flow while maintaining the retrograde outflow pressure at 0 mmHg. The PF characteristics of the total and intramural collateral circulations could be fitted by either a second-degree polynomial or linear equation. In both cases the pressure intercept crossed the origin of the axes. The average contribution of intramural collaterals to total retrograde flow was 58 +/- 5%. We conclude that the PF characteristics of intramural collaterals parallel those of the total collateral circulation.

Coronary and myocardial adaptations to high altitude in dogs.

The objective of this study was to determine whether exposure to high altitude (hypoxic hypoxemia) induces coronary and/or collateral growth. Fourteen mongrel dogs were maintained at a simulated altitude of 18,000 ft for 1 mo and 7 dogs maintained for 3 mo. Within 2 days after their sojourn, the following data were obtained at ambient pressure: pulmonary, right heart chamber, and wedge pressures as well as cardiac output. On an isolated heart preparation, coronary and collateral flows were determined; each vessel was injected with a different color tracer; and the heart was sliced, separated by perfusion territories, and examined for myocardial hypertrophy. We found that pulmonary artery pressures in altitude-adapted animals were higher compared with controls, and coronary flow per gram was increased after 1 mo of exposure but not different from control after 3 mo. Collateral flows were not significantly different from that of control animals, and biventricular hypertrophy occurred with right ventricular dominance. Comparing these results with those that we obtained previously from anemic animals, we favor the hypothesis that oxygen availability rather than blood flow velocity is most likely linked to vascular growth.

Functional anatomical site of intramural collaterals in dogs.

The objectives of the present study were to determine quantitatively whether the retrograde flow measurement reflects the total flow from collateral vessels or overestimates or underestimates collateral flow, and to determine the functional anatomical origin of intramural collaterals in the native dog heart. In an isolated heart preparation, three experimental procedures were used. 1) The left circumflex coronary artery was embolized with microspheres of different sizes; then retrograde flows and the peripheral coronary pressures were measured. 2) Epicardial collaterals were cauterized, and retrograde flows were measured before and after cautery. 3) Epicardial collaterals were cauterized followed by embolization of the circumflex coronary artery with different size spheres. We found that 1) the retrograde flow measurement underestimates the total collateral flow to the circumflex coronary artery by approximately 25%, 2) intramural collateral flow constitutes 58 +/- 3.5% of the retrograde flow measurement, 3) the antegrade component of blood flow that is not measured during a retrograde flow measurement is from the intramural collateral circulation, and 4) the functional site of origin of intramural collaterals is greater than 25 microns but less than 80 microns in diameter. We conclude that, in our preparation, retrograde flow underestimates total collateral flow, and that intramural collateral flow is a major component of retrograde flow in the native dog heart.

Coronary sinus pressure has a direct effect on gradient for coronary perfusion.

In previous work from this laboratory we demonstrated that the coronary pressure-flow relationship exhibits a zero pressure intercept in the absence of the influence of the collateral circulation. In the present study we determined the effect of varying coronary sinus pressures on coronary perfusion. Specifically, we investigated whether coronary flow would cease when the coronary inflow pressure equaled the coronary sinus pressure. The study was performed while inflow perfusion pressure to all coronary vessels was changed simultaneously in order to reduce the influence of the collateral circulation while coronary sinus outflow was measured. Coronary pressure-flow relationships were obtained for coronary sinus pressures of 0, 10, and 20 mmHg. The results demonstrate a strong correlation between perfusion pressure and coronary sinus pressure (r2 = 0.994 +/- 0.001), which passed through the origin. We conclude that coronary sinus pressures between 0 and 20 mmHg have a direct influence on coronary perfusion.

Microvascular occlusions promote coronary collateral growth.

The objective of this study was to examine whether myocardial ischemia without alterations in pressure gradients between large epicardial coronary arteries was a sufficient stimulus to produce coronary collateral growth and development. To accomplish this aim, we partially embolized the circumflex coronary perfusion territory with 25-microns diameter microspheres to produce multiple microvascular occlusions, sufficient to abolish or greatly attenuate coronary vasodilator reserve. The embolization procedure was performed in two groups of dogs during aseptic surgery. After the dogs recovered for 1-3 wk (short-term embolization) or 6-8 wk (long-term embolization), indexes of vascular growth were compared with a group of control animals in which all operative procedures were performed, except embolization. Retrograde blood flow, an index of collateral blood flow and coronary vascular resistance, was determined in an isolated beating empty heart preparation during coronary vasodilation with adenosine. Circumflex retrograde blood flow from the left anterior descending artery was increased from 0.09 ml.min-1.g-1 (sham) to 0.21 and 0.17 ml.min-1.g-1 in the short-term and long-term groups, respectively (P less than 0.05). Collateral blood flow from the septal artery was also increased from 0.03 ml.min-1.g-1 (sham) to 0.08 ml.min-1.g-1 (P less than 0.05) in the short-term group. Collateral contribution from the right coronary artery was not significantly altered in either group of embolization animals. The contributions of epicardial and intramyocardial collaterals to the total retrograde flow were also determined and were found to be different among the three experimental groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Intramural coronary collateral flow in dogs.

The objective of this study was to determine whether intramural collaterals contribute significantly to total retrograde flow (index of collateral flow). The left circumflex, left anterior descending, right, and septal coronary arteries were separately cannulated, and blood flows through these vessels were monitored on an isolated, blood-perfused beating heart preparation. Epicardial collaterals between the borders of the circumflex and right coronary perfusion territories were cauterized, and retrograde flow from the circumflex coronary artery was determined before and after cauterization. This procedure unmasked the intramural collateral flow component to retrograde flow. By occluding and unoccluding the coronary flows from the right, septal, and left anterior descending coronary arteries during these measurements, we were able to determine their contribution to epicardial and intramural collateral flow. We found that, after cauterization, an average of 58 +/- 3.6% of the total retrograde flow remained. The septal and left anterior descending coronary arteries contributed almost equally to this retrograde flow. We concluded that, because the epicardial collaterals were cauterized, the source of retrograde flow was from intramural collaterals and constituted about one-half of the measured retrograde flow in dogs with a native collateral circulation.

Collateral influence on pressure-flow characteristics of coronary circulation.

The purpose of this study was to determine the role of the coronary collateral circulation on the shape of the coronary pressure-flow (P-F) relationship and its effects on the pressure at zero flow (PZF) or pressure intercept. We investigated the P-F characteristics of the coronary circulation under two conditions. 1) To minimize the influence of collaterals, we measured coronary flow by timed collections of coronary sinus outflow in 15 dog hearts, as perfusion pressure to all vessels was varied; 2) to maximize the effect of collaterals, we measured circumflex artery flow in six dog hearts, as perfusion pressure to only the circumflex coronary artery was varied and the pressure in the remaining vessels was maintained constant. We used an isolated heart preparation in which ventricular chamber and venous outflow pressures equalled atmospheric pressure and the vessels were maximally dilated with adenosine. In the first condition, the P-F relationship was curvilinear with a PZF of 0 mmHg; in the second condition, the P-F relationship was curvilinear with a PZF of 16 +/- 2 mmHg, and flow was retrograde at pressures below PZF. We conclude that in both conditions the curvilinearity of the coronary P-F relationship was the result of nonlinear elastic properties of blood vessels, not requiring the "waterfall" concept to be invoked, and that in the second condition the influence of collateral vessels produced the positive pressure intercept.

Regression and recovery of well-developed coronary collateral function in canine hearts after aorta-coronary bypass.

After restoration of antegrade blood flow by coronary artery bypass grafting to a region of myocardium supplied by well-developed collateral vessels, there is regression of collateral supply to that region. There is controversy as to how rapidly this regression occurs, how soon collateral flow might return after an acute occlusion of the bypass graft, and how effective pharmacologic agents such as nitroglycerin might be in accelerating this return. To investigate this problem, 14 canine hearts were collateralized by Ameroid occlusion of the left anterior descending coronary artery. Regression and recovery of well-developed collateral function were studied after opening and closing an aorta-coronary bypass. Before bypass, peripheral coronary pressure was 82 +/- 2 mm Hg, retrograde flow 63 +/- 7 ml/min, collateral flow 21 +/- 2 ml/min, and collateral resistance 0.96 +/- 0.13 mm Hg/ml/min. One hundred minutes of bypass perfusion significantly decreased peripheral coronary pressure by 27%, retrograde flow by 52%, and collateral flow by 42%, and significantly increased collateral resistance by 319%. When the bypass was acutely occluded for 30 minutes, collateral resistance decreased spontaneously by 37%. When intracoronary nitroglycerin was administered for 5 minutes immediately after bypass occlusion, collateral resistance rapidly decreased by 72%, but subsequent collateral regression was not alleviated. Increased flow through regressed collateral vessels during retrograde flow diversion was associated with a decrease in collateral resistance. Results demonstrate rapid but not instantaneous regression and recovery of mature collateral function in response to requirements of collateral-dependent myocardium. Regressed collateral vessels can be dilated by nitroglycerin. Flow-dependent changes in collateral vascular tone appear to be responsible for early regression and recovery of collateral function.

Pressure-flow characteristics of coronary collaterals in dogs.

In this study we utilized two methods to investigate the pressure-flow, P-F, relationship of the coronary collateral vessels in a beating, blood-perfused, isolated heart preparation. In the first method (free-flow method), 12 dog hearts were perfused at pressures ranging from 100 to 0 mmHg, whereas the retrograde flow (index of collateral flow) was measured on the circumflex coronary artery, LCA, against atmospheric pressure, first during autoregulation and then after maximum vasodilation. In the second method (back-pressure method), the back pressure to retrograde flow was varied from 0 to 100 mmHg, whereas the perfusion pressure to the remaining vessels was maintained constant at 100 mmHg. This procedure was performed on four hearts with and without embolization of the LCA by 25-microns spheres. The free-flow method demonstrated a linear P-F relationship with an average correlation coefficient, r, of 0.98. The pressure intercept was 1.7 +/- 1.2 mmHg. The back-pressure method yielded a relationship that was more curvilinear with an average pressure intercept of 13 mmHg without embolization and 38 mmHg with embolization. An analog of the coronary and collateral circulation was used to illustrate that, in the back-pressure method, changes in the coronary resistance at low pressures contributed to the nonlinearity of the collateral P-F characteristics and that the network formed between the collateral and coronary resistances was responsible for the higher pressure intercept value.