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Notes: YBa2Cu3O7 films on sapphire substrates prepared by laser ablation show c-axis-oriented growth and critical temperatures as high as Tc(R=0)=90 K. Due to diffusion processes and the formation of a nonsuperconducting intermediate layer the critical current density Jc is comparatively low. To overcome these difficulties the sapphire substrates were covered by Zr(Y)O2 films acting as diffusion barriers. The preparation of these films was performed by laser ablation using a multitarget system. The structure and the surfaces of the films were characterized by x-ray diffraction and scanning electron microscopy, respectively. The transport properties of the superconductor films are similar to those on suited substrates. Critical current densities up to Jc (77 K)=5×105 A/cm2 were achieved. In order to gain information about the pinning mechanisms measurements of the dependencies of Jc on the orientation between the crystal c axis and the external magnetic fields were carried out using samples with different buffer layer thicknesses. From the received data no indication of pinning by point defects in addition to the intrinsic planar pinning mechanism was detected.

Notes: Abstract  Objectives: Resternotomy is a common part of cardiac surgical practice. Associated with resternotomy are the risks of cardiac injury and catastrophic hemorrhage and the subsequent elevated morbidity and mortality in the operating room or during the postoperative period. The technique of direct vision resternotomy is safe and has fewer, if any, serious cardiac injuries. The technique, the reduced need for groin cannulation and the overall low operative mortality and morbidity are the focus of this restrospective analysis. Methods: The records of 495 patients undergoing 546 resternotomies over a 21-year period to January 2000 were reviewed. All consecutive reoperations by the one surgeon comprised patients over the age of 20 at first resternotomy: M:F 343:203, mean age 57 years (range 20 to 85, median age 60). The mean NYHA grade was 2.3 [with 67 patients (I), 273 (II), 159 (III), 43 (IV), and 4 (V classification)] with elective reoperation in 94.6%. Cardiac injury was graded into five groups and the incidence and reasons for groin cannulation estimated. The morbidity and mortality as a result of the reoperation and resternotomy were assessed. Results: The hospital/30 day mortality was 2.9% (95% CI: 1.6%-4.4%) (16 deaths) over the 21 years. First (481), second (53), and third (12) resternotomies produced 307 uncomplicated technical reopenings, 203 slower but uncomplicated procedures, 9 minor superficial cardiac lacerations, and no moderate or severe cardiac injuries. Direct vision resternotomy is crystalized into the principle that only adhesions that are visualized from below are divided and only sternal bone that is freed of adhesions is sewn. Groin exposure was never performed prophylactically for resternotomy. Fourteen patients (2.6%) had such cannulation for aortic dissection/aneurysm (9 patients), excessive sternal adherence of cardiac structures (3 patients), presurgery cardiac arrest (1 patient), and high aortic cannulation desired and not possible (1 patient). The average postop blood loss was 594 mL (95% CI:558–631) in the first 12 hours. The need to return to the operating room for control of excessive bleeding was 2% (11 patients). Blood transfusion was given in 65% of the resternotomy procedures over the 21 years (mean 854 mL: 95% Cl 765–945 mL) and 41% over the last 5 years. Conclusions: The technique of direct vision resternotomy has been associated with zero moderate or major cardiac injury/catastrophic-hemorrhage at reoperation. Few patients have required groin cannulation. In the postoperative period, there was acceptable blood loss, transfusion rates, reduced morbidity, and moderate low mortality for this potentially high risk group.

Notes: Abstract  Objectives and Methods: Reoperations are an integral part of a cardiac surgeon's practice. We share our experience of 546 reoperations over the last 21 years to January 2000, with the focus directed towards the timing of reoperation, reducing the mortality and morbidity of reoperation and rereplacement aortic valve surgery, and understanding the important risk factors. In addition, the precise technical steps that facilitate careful successful explantation of various devices (allograft, stented and stentless xenografts, and mechanical valves) are detailed. Results: Optimal planned reoperation before deterioration to New York Heart Association Class III/IV levels and before unfavorable cardiac and comorbidity general system failure occurs has produced low mortality and morbidity as compared with first operation results. However, unfavorable delays and late rereferral result in mortality rates of up to 22% for emergency redo AVR for degenerated bioprostheses. Conclusion: Cardiac surgical units have the opportunity to establish a closer patient-surgeon relationship, which favors, when necessary, the optimal timing of reoperation. Knowledge of the more important risk factors and adherence to specific technical steps at explantation of various devices enhances satisfactory reoperation outcomes.

Notes: Objective To determine whether placental vascular endothelial growth factor (VEGF) is increased in pre-eclampsia.Design Prospective cohort study.Setting Royal Prince Alfred Hospital, Sydney, Australia.Sample Eleven normotensive women and eight women with pre-eclampsia matched for age and gestation.Methods Uterine artery Doppler ultrasound flow velocity profiles were recorded in the third trimester and resistance index calculated as (Vs-Vd)/Vs (Vs= peak systolic flow velocity, Vd= end diastolic flow velocity). Placental tissue at delivery was examined for VEGF distribution with avidin-biotin-peroxidase immunohistochemistry.Results Uterine resistance index [median (range)] was significantly increased in pre-eclamptic women (normotensive: 0.42 (0.36–0.51); pre-eclampsia: 0.59 (0.40–0.75); P= 0.005). Notching of the uterine artery waveform, consistent with a high resistance circulation, was evident in early diastole in five women with pre-eclampsia but only one normotensive woman (P= 0.013). Placental VEGF was increased in women with pre-eclampsia in the decidual trophoblast (normotensive: 34% (4–59) cells stained for VEGF; pre-eclampsia: 58% (15–95); P= 0.033) and in the villous syncytiotrophoblast (normotensive: VEGF count 1.4 arbitrary units (1.1–2.1); pre-eclampsia: 1.8 arbitrary units (1.4–2.2); P= 0.041). Analysis indicated that uterine artery resistance index was directly correlated with placental VEGF staining, mean arterial pressure and birthweight.Conclusions Abnormal uterine artery Doppler ultrasound flow velocity profiles in pre-eclampsia indicate increased uteroplacental resistance. The associated increase in placental VEGF may represent a compensatory mechanism attempting to restore blood flow towards normal.

Notes: YBa2Cu3O7−δ/Y0.3Pr0.7Ba2Cu3O7−δ /YBa2Cu3O7−δ Josephson junctions have been prepared by a multistep laser ablation process using an improved shadow mask technique. Junctions with barrier layer thicknesses larger than 12 nm exhibit current-voltage characteristics which are close to those predicted by the resistively shunted junction (RSJ) model. Under microwave irradiation, clear Shapiro steps, which could be well described by the RSJ model, occur in the current-voltage curves. From the exponential decrease of the critical current density with increasing barrier layer thickness, an order parameter decay length ξn of 21±4 nm at T=4.2 K has been determined for Y0.3Pr0.7Ba2Cu3O7−δ. The increase of the junction resistance with decreasing temperature indicates that the barrier layer dominates the junction properties.