Fast synthesis of ultrathin ZnO nanowires by oxidation of Cu/Zn stacks in low-pressure afterglow.

The synthesis of ultrathin, single-crystalline zinc oxide nanowires was achieved by treating in a flowing microwave plasma oxidation process, zinc films coated beforehand by a sputtered thin buffer layer of copper. The aspect ratio of the nanowires can be controlled by the following experimental parameters: treatment duration, furnace temperature, oxygen concentration. An average diameter of 6 nm correlated with a mean length of 750 nm can be reached with a fairly high surface number density for very short treatments, typically less than 1 min. The oxidized samples are characterized by means of SEM, XRD, SIMS, HRTEM and EDX techniques. Structural characterization reveals that these nanowires are single-crystalline, with the wurtzite phase of ZnO. Nanowires are only composed of ZnO without copper particles inside or at the end of the nanowires. Temperature-dependent photoluminescence measurements confirm that ZnO nanowires are of high crystalline quality and thin enough to produce quantum confinement.

Comparison of polyclonal antibody sera for early prophylaxis following cardiac transplantation.

In order to test different polyclonal antibody regimes as early prophylaxis against cardiac rejection, 42 patients (ages 30 to 60 years) transplanted at the University of Michigan from December 1986 to August 1988 were randomized to receive antithymocyte globulin (ATGAM, Upjohn, n = 19) or antilymphoblast globulin (MALG, University of Minnesota, n = 23). Cyclosporine (CYA), steroids, and azathioprine (AZA) administration was similar in all randomized patients during early prophylaxis. CYA was begun preoperatively and maintained at a serum level of 250-300 ng/ml. After an initial steroid taper, patients were maintained on 0.3 mg/kg/day. AZA was begun after polyclonal prophylaxis at 1-2 mg/kg. All patients received either ATGAM or MALG for 7 days or until the serum CYA reached 250 ng/ml. Although sex, pretransplant hemodynamics, follow-up length, total drug dose, mortality (one per group), postoperative white blood cell and lymphocyte counts did not differ between groups, MALG significantly delayed the first rejection episode as compared to ATGAM (35 +/- 4 vs 22 +/- 3 days, P less than 0.05). Additionally, there was decreased rejection during follow-up for the MALG group with 1.5 +/- 0.2 rejections per patient as compared to 2.3 +/- 0.3 with ATGAM. Furthermore, the significant infection rate with MALG was only half that of the ATGAM group (6/23 vs 11/19) (P less than 0.05). The beneficial effect of MALG may be due to immune-specific differences in its polyclonal spectrum.

Cytoimmunologic monitoring and heart transplantation.

Cytoimmunologic monitoring (CIM) combines morphological quantitation of activated lymphocytes and immunoblasts with immunophenotyping of peripheral blood in an effort to identify patients at risk for heart transplant rejection. In this study, CIM and endomyocardial biopsy (EMB) results were correlated in 55 paired blood and tissue specimens obtained from 18 heart transplant patients after operation. We found that 83% of patients with rejection and 81% of patients without rejection had increased levels of morphological activated lymphocytes. Multiple other criteria for determining levels of activation were used without improving the sensitivity or specificity. The use of CD4:CD8 ratios to discriminate between activation caused by rejection and those from viral infections and other inflammatory conditions yielded a sensitivity of 43% and specificity of 56%. The presence of activation markers such as I2, TAC, and T9 did not correlate with either CIM or EMB findings. CD4:CD8 alone was not predictive of cardiac rejection as increased, normal, and decreased CD4:CD8 ratios were seen in patients with and without rejection. Other measurements such as percentage of activated lymphocytes, total lymphocyte count, and whole blood cell count did not correlate with EMB or immunophenotypic findings. These results indicate that neither CIM, as currently conducted, nor immunophenotyping alone is sensitive or specific enough to substitute for EMB in screening for tissue rejection.

Methylprednisolone pulsing of heart transplant patients in the home.

Methylprednisolone pulsing is the first form of treatment used to reverse acute moderate rejection in heart transplant patients at the University of Michigan, Ann Arbor. Before May 1986, patients who needed administration of medications to be pulsed were admitted to the hospital. With our increasing number of transplant patients, lack of hospital beds, and efforts toward cost containment, a new system was established. From June 1986 to April 1988, 53 heart transplantations were performed in 40 adults and 13 children. Home care agency nurses received in-service training by the heart transplant clinical specialist. Insurance companies were contacted directly to obtain financial approval when it was not considered a covered benefit. Of 47 episodes of rejection, 45 were successfully treated in the home with resolution, whereas hospital admission was required in two cases of rejection episodes for successful resolution. There were marked financial savings, increased patient satisfaction, no patient infections, and minimal side effects, which included hypertension in five patients, headaches in two patients, and difficulty gaining venous access in two patients. Most problems were easily handled by telephone communication. Therefore, after a 22-month experience with administration of methylprednisolone pulses in the home, we believe that this is a satisfactory method of treating patients. It is cost-effective, has minimal side effects, and leads to increased patient satisfaction.