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Biomedical subjects

G Uretzky

Publications and source records attributed to G Uretzky.

At least 19 recordsLinked to original sources
PubMed2005

Ischaemia or reperfusion: which is a main trigger for changes in nitric oxide mRNA synthases expression?

OBJECTIVE: To investigate alterations in endothelial nitric oxide synthase and inducible nitric oxide synthase mRNA expressions and nitric oxide release in the myocardium during ischaemia/reperfusion and determine whether these changes are ischaemic and/or reperfusion dependent. MATERIALS AND METHODS: Isolated rat hearts were perfused by a modified Langendorff system. Following 1 h of global cardioplegic ischaemia, left ventricle haemodynamic parameters were recorded at baseline and during 30 min of reperfusion. Levels of endothelial, inducible nitric oxide synthases mRNA expression and nitric oxide release were measured at baseline, after ischaemia and at 30 min of reperfusion. RESULTS: Global cardioplegic ischaemia caused a significant depression of left ventricular function and a decrease of coronary flow. Postischaemic intensities of the endothelial nitric oxide synthase mRNA bands were significantly lower than at baseline (P < 0.01). There were no significant differences in endothelial nitric oxide synthase mRNA band intensities immediately after ischaemia compared to the end of reperfusion, nor between the intensities of inducible nitric oxide synthase mRNA bands at baseline, at end of ischaemia and at end of reperfusion. Nitric oxide in the myocardial effluent was below detectable levels at all measured points. CONCLUSION: Ischaemic injury causes down-regulation of endothelial nitric oxide synthase mRNA expression, which is then associated with reduction of coronary flow during reperfusion, representing one possible mechanism of ischaemia/reperfusion injury. We did not find expected elevations of inducible nitric oxide synthase mRNA expression during ischaemia or reperfusion and we suggest that ischaemia/reperfusion injury is not associated with nitric oxide overproduction.

Animals↗
PubMed2003

Technical aspects of harvesting the radial artery with the harmonic scalpel.

BACKGROUND: Harvesting the radial artery (RA) with ultrasonic dissection with the Harmonic Scalpel reduces spasm induced by surgical handling. Topical exposure to phentolamine methanesulphonate (Regitine) exerts an additional effect of vasodilatation. METHODS: Between January and December 2002, the RA was harvested as a pediculated vessel with the Harmonic Scalpel in 145 consecutive patients undergoing myocardial revascularization. A fasciotomy of the pedicle was performed after harvest ing. A composite graft with the reverse free RA on the in situ left internal thoracic artery (ITA) was prepared before the construction of distal coronary anastomoses. The RA was then placed in a syringe filled with Regitine (0.07 microg/mL) for 10 minutes. \par RESULTS: The mean number of grafts/patient was 3.0. The mean number of RA anastomoses was 2.0/patient. Left ITA free flow was 105 +/- 34 mL/min. Regitine increased the RA free flow from 60 +/- 35 mL/min to 82 +/- 30 mL/min (P <.05). Fourteen patients underwent postoperative coronary angiography. All RA anastomoses were patent. CONCLUSION: The compound effect of RA harvesting with the Harmonic Scalpel and topical treatment with the alpha- blocking agent Regitine increases the RA free flow and significantly decreases intraoperative spasticity.

Aged↗
PubMed2003

Midterm results of routine bilateral internal thoracic artery grafting.

BACKGROUND: Skeletonized dissection of the internal thoracic artery (ITA) decreases the occurrence of sternal devascularization, thus decreasing the risk of postoperative sternal complications in patients undergoing bilateral ITA grafting. METHODS: From April 1996 to July 1999, 1000 consecutive patients underwent bilateral skeletonized ITA grafting. Of the 770 male and 230 female patients, 420 were older than 70 years, and 312 had diabetes. RESULTS: Operative mortality was 3.3%. Follow-up (40-78 months) revealed 79 late deaths, and the Kaplan-Meier 6-year survival rate was 88%. Cox regression analysis revealed increased overall mortality (early and late) in patients with preoperative congestive heart failure (risk ratio [RR], 2.13; 95% confidence interval [CI], 1.31-3.45), in patients with peripheral vascular disease (RR, 5.52; 95% CI, 3.31-9.19), and in patients older than 70 years (RR, 2.18; 95% CI, 1.37-3.47). Early postoperative morbidity included sternal infection (2.2%), cerebrovascular accident (1.6%), and perioperative myocardial infarction (1%). Multiple regression analysis showed repeat operation (odds ratio [OR], 7.5; 95% CI, 1.77-31.6) and chronic obstructive pulmonary disease (OR, 3.6; 95% CI, 1.27-10.75) to be independent predictors of sternal infection. During follow-up, angina returned in 95 patients, 24 of whom required reintervention (20 cases of percutaneous balloon angioplasty and 4 reoperations). Postoperative coronary angiography performed in 87 patients revealed an ITA patency rate of 91%. CONCLUSIONS: Bilateral skeletonized ITA grafting is associated with satisfactory early and midterm results. We do not recommend the use of this surgical technique in patients with chronic obstructive pulmonary disease.

Aged↗
PubMed2002

Pretreatment with alpha-adrenergic blockers for prevention of radial artery spasm.

BACKGROUND: Radial artery (RA) conduits are prone to early vasospasm. Current intraoperative treatment with papaverine fails to inhibit postoperative RA constriction. Pretreatment with topical a-antagonist solutions can inhibit RA vasoconstriction and cause dilatation for a longer period than achieved with papaverine. METHODS: In 10 patients undergoing myocardial revascularization, the radial artery was harvested as a skeletonized vessel. A composite graft with reverse free RA on an in situ left internal thoracic artery was prepared before construction of distal coronary anastomoses. The RA pedicle was then put in a small syringe filled with Regitine (phentolamine methansulphonic, 0.07 mg/mL) ("Jacuzzi") and warmed by immersing the container in a warm saline bath for 8 to 15 minutes. The RA free flow was measured before and after topical treatment with Regitine. RESULTS: The mean number of grafts per patient was 2.9 (range 2 to 4). The mean number of radial anastomoses was 1.8 per patient. Left internal thoracic artery free flow was 110 +/- 29 mL/min. Regitine increased radial free flow from 49 +/- 35 to 77 +/- 30 mL/min (p < 0.01). Five patients underwent postoperative coronary angiography. All radial anastomoses were patent. CONCLUSIONS: Topical treatment of RA with Regitine increases RA free flow and is an effective intraoperative means of decreasing RA spasticity.

Adrenergic alpha-Antagonists↗
PubMed2001

Characterisation of acute myocardial ischaemia in a canine model based on principal component analysis of unipolar endocardial electrograms.

The study presents a method for identifying endocardial electrical features relevant to local ischaemia detection at rest. The method consists of, first, normalisation of electrograms to a uniform representation; secondly, the use of principal component analysis to reduce the dimensionality of the electrogram vector space; and, thirdly, a search for a classification axis that matches the degree of ischaemia present in the tissue. Left ventricular myocardial states were assessed by echocardiography and NOGA mapping in eight dogs at baseline and then immediately after, 5h after and 3 days after occlusion of the left anterior descending coronary artery. Five principal components were required to approximate electrograms with an average error of less than 10% of the peak-to-peak amplitude. Correlations of 0.77, 0.80 and 0.84 were obtained between the principal component-based parameters and the echocardiography scores at the three ischaemic stages, respectively. Expression of these parameters in the time domain showed that the major changes occurred in the depolarisation segment of the endocardial electrogram as well as in the ST-segment. In conclusion, the proposed method provides a suitable alternative co-ordinate system for the classification of ischaemic regions and highlights signal segments that change as a result of pathology.

Acute Disease↗
PubMed2001

Three-dimensional electromechanical mapping: imaging in the operating room of the future.

BACKGROUND: Three-dimensional electromechanical mapping has previously been shown to be a clinically important tool for cardiac imaging and intervention. We hypothesized that this technology may be beneficial as an intraoperative modality for assessing cardiac hemodynamics and viability during cardiac surgery. We report here the use of this technology as an imaging modality for intraoperative cardiac surgery. METHODS: The tip of a locatable catheter connected to an endocardial mapping and navigating system is accurately localized while simultaneously recording local electrical and mechanical functions. Thus the three-dimensional geometry of the beating cardiac chamber is reconstructed in real time. The system was tested on 6 goats that underwent acute dynamic cardiomyoplasty and on 5 dogs that underwent left anterior descending (LAD) coronary artery ligation. RESULTS: The electromechanical mapping system provided an accurate three-dimensional reconstruction of the beating left ventricle during cardiomyoplasty. After the wrapping procedure, significant end-diastolic area reduction was noted in the base and mid parts of the heart (948 +/- 194 mm2 vs 1245 +/- 33 mm2, p = 0.021; and 779 +/- 200 mm2 vs 1011 +/- 80 mm2, p = 0.016). The area of the cross-section of the apex did not change during the operation. Acute infarcted tissue was characterized 3 days after LAD ligation by concomitant deterioration in both electrical and mechanical function. CONCLUSIONS: By providing both a clear view of the anatomical changes that occur during cardiac surgery, and an accurate assessment of tissue viability, electroanatomic mapping may serve as an important adjunct tool for imaging and analysis of the heart during cardiac surgery

Animals↗
PubMed2001

Novel thermoregulation system for enhancing cardiac function and hemodynamics during coronary artery bypass graft surgery.

BACKGROUND: Myocardial ischemia, arrhythmias, and coagulopathies are associated with postoperative hypothermia. This study assessed the efficacy of a novel thermoregulation system in alleviating these events during coronary artery bypass graft (CABG) surgery. METHODS: Elective CABG surgery patients were randomized into either Allon thermoregulation (AT, n = 40) or routine thermal care (RTC, n = 20) groups in whom the maintenance of normothermia during the nonbypass phases of the operation was compared. The AT used patients' rectal temperature as reference data to monitor the maintenance of the water temperature circulating at 37 degrees C in a garment. Rectal temperature, patient hemodynamics, and cardiac-specific troponin I (cTnI) levels were assessed at the induction of anesthesia, 30 minutes into surgery, at discontinuation of bypass, end of surgery, and 2 hours postoperatively. RESULTS: Body temperature was higher in the AT group compared to the RTC group at all five time points. Cardiac index (CI) (L/min) was higher in the AT group, 2.5 +/- 0.5, 2.6 +/- 0.5*, 3.2 +/- 0.6*, 3.3 +/- 0.5*, 3.1 +/- 0.7 at the respective time points, compared to the RTC group, 2.3 +/- 0.6, 2.1 +/- 0.2, 2.6 +/- 0.7, 2.7 +/- 0.7, 2.7 +/- 0.7 (*p < 0.05). Systemic vascular resistance (SVR) (dyne x s)/cm5) was consistently lower in the AT patients. Enzyme levels were elevated in both groups but were less so in the AT patients. CONCLUSIONS: The AT system can efficiently maintain normothermia. The beneficial effects are expressed by reduced SVR, elevated CI, and lower levels of cTnI, which may show a possible attenuation of myocardial injury.

Adult↗
PubMed2001

Detailed endocardial mapping accurately predicts the transmural extent of myocardial infarction.

OBJECTIVES: This study delineates between infarcts varying in transmurality by using endocardial electrophysiologic information obtained during catheter-based mapping. BACKGROUND: The degree of infarct transmurality extent has previously been linked to patient prognosis and may have significant impact on therapeutic strategies. Catheter-based endocardial mapping may accurately delineate between infarcts differing in the transmural extent of necrotic tissue. METHODS: Electromechanical mapping was performed in 13 dogs four weeks after left anterior descending coronary artery ligation, enabling three-dimensional reconstruction of the left ventricular chamber. A concomitant reduction in bipolar electrogram amplitude (BEA) and local shortening indicated the infarcted region. In addition, impedance, unipolar electrogram amplitude (UEA) and slew rate (SR) were quantified. Subsequently, the hearts were excised, stained with 2,3,5-triphenyltetrazolium chloride and sliced transversely. The mean transmurality of the necrotic tissue in each slice was determined, and infarcts were divided into <30%, 31% to 60% and 61% to 100% transmurality subtypes to be correlated with the corresponding electrical data. RESULTS: From the three-dimensional reconstructions, a total of 263 endocardial points were entered for correlation with the degree of transmurality (4.6 +/- 2.4 points from each section). All four indices delineated infarcted tissue. However, BEA (1.9 +/- 0.7 mV, 1.4 +/- 0.7 mV, 0.8 +/- 0.4 mV in the three groups respectively, p < 0.05 between each group) proved superior to SR, which could not differentiate between the second (31% to 60%) and third (61% to 100%) transmurality subgroups, and to UEA and impedance, which could not differentiate between the first (<30%) and second transmurality subgroups. CONCLUSIONS: The degree of infarct transmurality extent can be derived from the electrical properties of the endocardium obtained via detailed catheter-based mapping in this animal model.

Animals↗
PubMed2001

Hemodynamic evaluation of descending aortomyoplasty versus intra-aortic balloon pump performed in normal animals: an acute study.

OBJECTIVE: Aortomyoplasty is a surgical procedure that aims to induce hemodynamic benefits similar to those of the intra-aortic-balloon-pump (IABP). The objective of this study was to compare the coronary blood flow augmentation and afterload reduction produced by IABP and descending aortomyoplasty counterpulsation. METHODS: From a series of fifteen mongrel dogs (18-35 kg), eight underwent acute descending aortomyoplasty and seven had IABP application. Left anterior descending (LAD) coronary artery blood flow was measured using a Doppler flow probe. Left ventricular pressure in addition to aortic pressures both proximal and distal to either the aortomyoplasty site or the IABP position were monitored continuously. All experiments were acute and performed in normal hearts. RESULTS: Descending aortomyoplasty induced a 27% increase in the LAD blood flow integral during assisted beats (14.0+/-6 ml/min integral compared to 10.8+/-4 ml/min integral in unassisted beats [P<0.001]). This was comparable to an 18% rise in the LAD blood flow integral during IABP counterpulsation (from 8.6+/-3 ml/min to 10.2+/-4 ml/min [P<0.001]). Conversely, while IABP counterpulsation reduced the left ventricular afterload by 16% (from 102+/-23 mmHg to 86+/-26 mmHg [P<0.001]), descending aortomyoplasty did not result in afterload reduction. CONCLUSIONS: Descending aortomyoplasty produces coronary blood flow augmentation comparable to that achieved by the IABP. This may be important for end-stage ischemic patients. However, afterload reduction achieved by the IABP was not reproduced during descending aortomyoplasty counterpulsation. The surgical technique of descending aortomyoplasty should be modified to attain afterload reduction, thus improving treatment for congestive heart failure patients.

Cardiomyoplasty↗
PubMed2001

Protamine cardiotoxicity and nitric oxide.

OBJECTIVES: The purpose of this study is to assess the role of the nitric oxide (NO) pathway in protamine-induced cardiotoxicity and to formulate a possible explanation for this adverse effect. METHODS: Isolated rat hearts were perfused by Krebs--Henseleit (KH) solution using a modified Langendorff model. They were randomized into three groups: A, 40 min perfusion with KH solution; B, 20 min perfusion with KH solution and 20 min with protamine; C, as B but Ng-monomethyl-L-arginine (L-NMMA), a non-selective inhibitor of the NO pathway, was added during 40 min of the perfusion period. Left ventricular (LV) function was measured every 10 min. NO and tumor necrosis factor-alpha (TNF) were detected in the effluent from the coronary sinus (CS) and in the supernatant of the cardiac myocytes culture. Nitric oxide synthases (NOS) mRNA levels were determined in groups A and B from LV samples at baseline and after 40 min of perfusion. RESULTS: We found that protamine at a dose of 12 microg/ml causes significant depression of LV function (decreased peak systolic pressure to 22.5+/-3.2% and dP/dt max to 22.9+/-3.1%). L-NMMA did not prevent protamine cardiotoxicity. NOS mRNA was not detected from LV samples in any group. The NO in the effluent from the CS and from the supernatant of the cardiomyocytes culture was below detectable levels. However, a significant amount of TNF was measured in the effluent from the CS (108+/-17 pg/min for group B and 117+/-13 pg/min for group C) and in the supernatant of the cardiomyocytes culture (65+/-21 pg/ml). CONCLUSIONS: This study suggests that direct protamine-induced cardiotoxicity does not depend on the NO pathway. Our finding that protamine induced TNF release by cardiomyocytes can shed new light on the understanding of protamine cardiotoxicity.

Animals↗
PubMed2001

A novel thermoregulatory system maintains perioperative normothermia in children undergoing elective surgery.

BACKGROUND: Body heat loss during anaesthesia may result in increased morbidity, particularly in high-risk populations such as children. To avoid hypothermia, a novel thermoregulatory system (Allon) was devised. We tested the safety and efficacy of this system in maintaining normothermia in children undergoing routine surgical procedures. METHODS: The system consists of a computerized body, which receives continuous afferent data, i.e. core (rectal) temperature. These data are then compared with a preset temperature (37 degrees C) and a microprocessor heating/cooling unit warms/cools the temperature of circulating water in a garment that is specially designed to allow maximal coverage of body surface area, without impingement on the surgical field. Water temperature to the garment was limited to a maximum of 39.5 degrees C. Continuous perioperative monitoring of skin and rectal temperature, heart rate and blood pressure was performed. Postoperative shivering and adverse effects were also assessed. RESULTS: The Allon system was used in 38 patients aged 3 months to 14 years undergoing surgery under general anaesthesia lasting more than 30 min. Fifty to 80% body surface area was covered by the garment. Mean operative and postoperative core temperatures were 36.9 +/- 0.5 degrees C and 36.7 +/- 0.5 degrees C, respectively. Intraoperative skin temperatures were maintained at 34.4 +/- 2.7 degrees C. The average core- to-periphery intraoperative gradient was 2.9 +/- 4.9 degrees C. Postoperative shivering was absent in 36 cases and mild in two cases. No device-related adverse effects were observed. CONCLUSIONS: Perioperative thermoregulation using the Allon system is safe and effective in maintaining body temperature within a narrow range in children undergoing brief surgical procedures.

Adolescent↗
PubMed2001

Three-dimensional endocardial impedance mapping: a new approach for myocardial infarction assessment.

Precise identification of infarcted myocardial tissue is of importance in diagnostic and interventional cardiology. A three-dimensional, catheter-based endocardial electromechanical mapping technique was used to assess the ability of local endocardial impedance in delineating the exact location, size, and border of canine myocardial infarction. Electromechanical mapping of the left ventricle was performed in a control group (n = 10) and 4 wk after left anterior descending coronary artery ligation (n = 10). Impedance, bipolar electrogram amplitude, and endocardial local shortening (LS) were quantified. The infarcted area was compared with the corresponding regions in controls, revealing a significant reduction in impedance values [infarcted vs. controls: 168.8 +/- 11. 7 and 240.7 +/- 22.3 Omega, respectively (means +/- SE), P < 0.05] bipolar electrogram amplitude (1.8 +/- 0.2 mV, 4.4 +/- 0.7 mV, P < 0. 05), and LS (-2.36 +/- 1.6%, 11.9 +/- 0.9%, P < 0.05). The accuracy of the impedance maps in delineating the location and extent of the infarcted region was demonstrated by the high correlation with the infarct area (Pearson's correlation coefficient = 0.942) and the accurate identification of the infarct borders in pathology. By accurately defining myocardial infarction and its borders, endocardial impedance mapping may become a clinically useful tool in differentiating healthy from necrotic myocardial tissue.

Algorithms↗
PubMed2000

[Videothorascopic sympathectomy (VATS) for palmar hyperhidriosis:summary of a clinical trial and surgical results].

Palmar hyperhidriosis is not a life-threatening disease but leads to loss in the quality of life. Conservative treatment is ineffective and major surgery involves perioperative complications and esthetic impairment. From 1992 to 1998 we treated 156 patients with palmar hyperhidriosis using a single port, drainless videothoracoscopic procedure with almost no complications.

Adolescent↗
PubMed2000

The efficacy of intraoperative internal intercostal nerve block during video-assisted thoracic surgery on postoperative pain.

BACKGROUND: Video-assisted thoracic surgery (VATS) is widely used for many thoracic surgical procedures. Post-operative pain is less after VATS than after conventional thoracic surgery, but is still significant. The objective of this study was to assess the efficacy of thoracoscopic, internal intercostal nerve block in alleviating immediate postoperative pain. METHODS: Thirty-two patients underwent VATS bilateral sympathectomy for the treatment of hyperhidrosis. The patients were randomly divided into two groups with similar demographic and preoperative physiologic parameters. Group A (n = 16) was submitted to thoracoscopic, internal intercostal nerve blocks performed at T2, T3, and T4 intercostal levels using 3 cc of 0.5% bupivacain in each intercostal space. The injections were performed bilaterally, immediately after the sympathectomy, through the same port. Group B (n = 16) underwent bilateral thoracic sympathectomy without the block. During the immediate postoperative period, heart rate, blood pressure, respiratory rate, pain score, and analgesic requirements were monitored every 30 minutes. RESULTS: No morbidity was recorded in association with the thoracoscopic, internal intercostal nerve block. The mean heart rates (77 +/- 6 vs 89 +/- 12 beats per minute, p < 0.001), respiratory rates (15 +/- 2 vs 18 +/- 3 respirations per minute, p < 0.01), pain score (1.9 +/- 0.6 vs 2.7 +/- 0.5, p < 0.01), and postoperative analgesic requirements (20 +/- 18 vs 50 +/- 21 mg pethidine HCL, p < 0.001) were significantly lower in group A. There was no significant difference in blood pressures. CONCLUSIONS: Thoracoscopic, internal intercostal nerve block with bupivacain 0.5% during VATS is safe and effectively reduced the immediate postoperative pain and analgesic requirements.

Adolescent↗
PubMed2000

Hemodynamic changes and right heart support during vertical displacement of the beating heart.

BACKGROUND: Hemodynamic instability during heart displacement in off-pump multivessel coronary artery bypass grafting might be related to right heart dysfunction. The Enabler (HemoDynamics Systems Ltd, Upper Yoqneam, Israel) is a cannula pump that expels blood from the right atrium into the pulmonary artery. We studied the hemodynamic changes and the role of the enabler during heart displacement. METHODS: Nine anesthetized sheep were assessed for hemodynamic changes during 90-degree heart displacement with or without Enabler support. Hemodynamic parameters included cardiac output, systemic arterial blood pressures, and left and right heart filling pressures. RESULTS: Heart displacement caused a significant decrease in cardiac output and systemic blood pressure (46%+/-5%, p = 0.001; and 20%+/-5%, p = 0.009, respectively), with a concomitant 137%+/-24% (p = 0.003) increase in central venous pressure. No significant change in left atrial pressure was observed. Activation of the Enabler caused a significant increase in cardiac output and systemic blood pressure (67%+/-15%, p = 0.01; and 17%+/-7%, p = 0.04, respectively), as well as a decrease in central venous pressure by 49%+/-8% (p = 0.0001). CONCLUSIONS: Heart displacement causes hemodynamic instability mainly by right heart dysfunction. The Enabler significantly stabilized circulation during vertical displacement of the beating heart.

Animals↗
PubMed2000

Coping strategies, life style changes, and pessimism after open-heart surgery.

A mail questionnaire was completed by 171 patients two to 20 months after undergoing coronary artery bypass graft surgery (CABG). The post-CABG period was characterized by fewer working hours, a higher level of physical exercise, a reduction in smoking, and more appropriate nutritional habits, compared with the preoperation period. At the same time, the anxiety level of post-CABG patients was higher than that measured in a community sample. Post-CABG high psychological distress (anxiety and mood states) and low functional capacity were associated with high levels of pessimism and ineffective emotion-focused coping strategies. These results may be used by social workers in devising psychological interventions aimed at improving post-CABG patients' quality of life and bolstering their coping strategies.

Adaptation, Psychological↗
PubMed2000

Pharmacokinetics of vancomycin administered as prophylaxis before cardiac surgery.

Vancomycin concentrations in serum, tissues, and sternum, administered as prophylaxis to patients during coronary artery bypass surgery, were measured. Vancomycin (15 mg/kg) was administered to 15 patients 1 hour before skin incision. Blood, tissue, and sternum samples were collected before, during, and after bypass. The concentration in serum at the end of infusion was 55.1 +/- 22.8 microg/mL, the mean elimination half-life was 9 +/- 4 hours, the areas under the concentration-time curve (AUC) from 0 to 12 hours and from 0 to infinity were 90.6 +/- 25.1 and 289.7 +/- 86.5 microg/h per mL, respectively, the mean residence time (MRT) was 11.9 +/- 5.0 hours, the mean volume of distribution was 51.1 +/- 12.2 L, and the total clearance was 78.3 +/- 32.6 mL/min. Vancomycin concentrations in serum, tissues, and sternum during the operation were greater than the MIC90 for most staphylococci and ranged from 16 to 55 microg/mL in serum and from 4 to 39 microg/g in sternum and tissues.

Adult↗