Frequency-agile rf notch filter that uses photorefractive two-beam coupling

We describe a novel rf signal-filtering system based on photorefractive two-beam coupling implemented as a notch-filter transfer function for rf signals. By using a locally generated signal, the notch location in frequency can be tuned over a wide rf spectral band.

Intermediate-term outcome of renal retransplants in the cyclosporine era

To determine the influence of selected parameters on intermediate-term outcome of renal retransplants, univariate and multiple regression analyses were performed on all 100 consecutive cyclosporine treated retransplants performed between 1984 and 1990 (mean follow up, 4.6 +/- 2.3 years). Actual 1 year and actuarial 5 year graft survivals were higher in living compared with cadaver donor transplants (84% and 79% vs 69% and 56%, respectively; p < 0.05). Among cadaver donor transplant recipients, allografts with immediate early function had better 1 and 5 year graft survivals when compared with those with delayed function (81% and 62% vs 59% and 38%, respectively; p < 0.05). Recipients with acute rejection had inferior 1 year and 5 year graft survivals when compared with rejection free patients (65% and 35% vs 80% and 57%, respectively; p < 0.05). Graft survival time of primary transplants was also a significant predictor of retransplant outcome with 1 and 5 year graft survivals of 50% and 36%, respectively, in patients in whom primary grafts survived less than 3 months, compared with 75% and 58% in those in whom grafts survived longer than 3 months (p < 0.05). Recipient age, race, renal disease, and levels of panel reactive antibodies had no effect on intermediate-term outcome. In a multiple regression analysis, delayed graft function, acute rejection, and primary graft survival time less than 3 months correlated inversely with long-term survival of retransplants (multiple r = 0.65). A total of 39 grafts were lost due to rejection (22), sepsis (6), graft nonfunction (5), death with a functioning graft (4), noncompliance (1), and recurrent renal disease (1).(ABSTRACT TRUNCATED AT 250 WORDS)

Erythrocytosis after renal transplantation. A prospective analysis

A prospective analysis of all cyclosporine treated renal transplants performed between 1987 and 1990 was performed to determine the incidence and etiologic factors of post transplant erythrocytosis (PTE) and its effect on short-term outcome. PTE developed in 25 (8.1%) recipients (mean age, 41 +/- 10 years). PTE occurred more frequently in men (12.8%) than women (1.6%) (p < 0.001), diabetic patients (22.9%) than nondiabetic patients (6.2%) (p < 0.001), and rejection-free recipients (11%) compared with those with early rejection (4%) (p < 0.05) but was independent of recipient race and donor source. Sixteen patients in whom PTE subsequently developed had pretransplant hematocrits above 30%. PTE occurred most frequently in the first year posttransplant (range, 2-29 months). Serum erythropoietin levels were inappropriately elevated in all patients (mean, 24 +/- 2.2 mU/ml), but serum iron, folate, and B12 levels were all normal. Mean serum creatinine and creatinine clearance were 1.7 +/- 0.5 mg/dl and 58 +/- 20 ml/min, respectively. Twenty-three patients underwent phlebotomy (mean, 3.5 +/- 0.5 units) and six had PTE-related complications. In 14 patients, PTE persisted with hematocrit of 53 +/- 1.5% (range, 51-56) compared with 57 +/- 2.6% (range, 54-64) at the time of PTE onset. In conclusion, PTE occurs primarily in the first year posttransplant and is characterized by inappropriate elevation of erythropoietin. Predictors for PTE include male gender, diabetes mellitus, pretransplant hematocrit above 30%, absence of rejection, and excellent renal allograft function.

The influence of mode of dialysis pretransplantation on long-term renal allograft outcome

To determine the influence of the need and the mode of dialysis prior to transplantation on long-term renal allograft survival and subsequent renal function, all 662 consecutive cyclosporine-treated renal transplants (484 cadaver and 178 living-related donors), performed between 1983 and 1989 were retrospectively analyzed. Recipients were divided into 3 groups as follows: group I and II recipients underwent hemodialysis and peritoneal dialysis, respectively, prior to transplantation; group III patients were transplanted without dialysis. All groups were similar with respect to demographic and immunologic characteristics, apart from a higher proportion of diabetic and White patients in both cadaver and living-related group III recipients and a fewer number of blood transfusions among living-related group III recipients. A trend toward a decreased incidence of dialysis dependence in the early posttransplant period was noted among cadaver donor recipients in group III (20%) when compared to group I and II patients (36% and 26%, respectively). The incidence of rejection episodes was similar in all groups. No difference in 1- and 5-year patient survival was noted among all recipient groups. Actual 1-year graft survivals in groups I, II, and III were similar (73%, 72%, and 74%, respectively, for cadaver donor; and 86%, 89%, and 91%, respectively for living-related donor recipients). Likewise, actuarial 5-year graft survivals were not significantly different (53%, 51%, and 67%, respectively, for cadaver donor; and 75%, 69%, and 82%, for living-related donor recipients). Renal function, as assessed by serum creatinine concentration, was similar and stable in all recipient groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Optical image processing by matched amplification

An image-processing technique, which we call matched amplification, is proposed and demonstrated. Analogous to the well-known technique of matched filtering, matched amplification manipulates an input image at its Fourier plane by using a Fourier transform of a reference image. In matched amplification, however, the Fourier components of the input image that matchthose of the reference image are amplified rather than attenuated as in the case of matched filtering. Owing to this amplification process, matched amplification is advantageous for applications that require cascadability, high energy efficiency of the processed image, or large intensity dynamic range of the input image. We show experimental results using photorefractive two-beam coupling in BaTiO(3) as the coherent amplification stage.

The influence of nephrectomy of the primary allograft on retransplant graft outcome in the cyclosporine era

The present analysis was undertaken to evaluate the influence of primary allograft nephrectomies on the early function, incidence of rejection, and short-term graft survival of subsequent renal retransplants. Among 95 consecutive cyclosporine treated retransplant recipients, 52 were retransplanted without primary allograft nephrectomy; 35 had removal of their primary grafts prior to retransplantation for fever and graft tenderness (30 patients) and persistent hematuria (5 patients); and 8 patients had an elective primary graft nephrectomy at the time of retransplantation. Demographic characteristics and immunosuppressive regimens were otherwise similar in all three groups. Nephrectomy of the primary allograft prior to retransplantation was associated with a significant subsequent rise in preformed cytotoxic antibody levels (57% having PRA greater than 30% compared with 33% in those with retention of primary grafts), a significantly higher incidence of delayed graft function among retransplants (63% compared with 30% in those who did not undergo primary allograft nephrectomy) and a trend toward decreased allograft survival in the subgroup who lost their primary allografts in the first year posttransplant. The incidence of acute rejection and 3-year posttransplant renal function in retransplants were not, however, influenced by nephrectomy of the primary allograft.

Causes of late renal allograft failure in the ciclosporin era

A single center experience of 514 ciclosporin-treated renal allografts which survived longer than 1 year was reviewed in order to analyze the causes of renal allograft loss beyond the 1st year post-transplantation and the contribution of selected parameters to long-term survival. 83 grafts were lost between 1 and 5 years with the most common causes of graft loss being chronic rejection (54%), death (14%), noncompliance (13%) and sepsis (11%). Actuarial 5-year graft survival rates, decaying from 100% at 1 year, of living related and cadaveric grafts were 88.6 and 79.5%, respectively. Parameters with a substantial influence on long-term survival included the quality of early graft function and incidence of acute rejection in the 1st year post-transplantation. A marker for long-term survival (> 5 years) was a significantly lower serum creatinine (177 mumol/l; < or = 2 mg/dl) at 1 year. We conclude that chronic rejection is responsible for the majority of late graft losses in the ciclosporin era as in the earlier azathioprine period.

Orthotopic hepatic transplantation in the dog

Orthotopic hepatic transplantation has become a well-established treatment modality for end-stage liver disease, and research in this field is constantly evolving. Of the 34 canine liver transplants performed in this study, 17 (50%) survived more than 3 days (mean survival time 15 days). Causes of perioperative death included hemorrhage (4), anesthetic complications (3), systemic anaphylaxis (3), portal vein thrombosis (3), hepatic venous outflow block (2), and hepatic artery thrombosis (2). Gentle handling with minimal dissection of the donor liver in situ resulted in a decreased incidence of hepatic venous outflow block. The incidence of biliary leak was similar irrespective of the method of biliary reconstruction, although the incidence of acute cholangitis was 56% in the cholecystoduodenostomy group compared with 0% in the choledochocholedochostomy cohort. Using celiac to common hepatic end-to-side arterial anastomosis with preservation of the gastroduodenal artery, thrombosis of the hepatic artery was encountered in four instances, an incidence similar to previously reported studies where end-to-end hepaticohepatic arterial anastomosis or donor aortic conduit was utilized. The incidence of postoperative intestinal intussusception was reduced from 40 to 0% in those who underwent transmesenteric intestinal plication following implantation of the liver. Among short-term survivors, sepsis was the most frequent noted complication (10), followed by intestinal intussusception (6), rejection (6), and gastrointestinal bleeding (1). Among recipient dogs that survived more than 3 days, rejection was the most common cause of graft loss (5), followed by biliary leak (4) and hepatic artery thrombosis (2).

Marchiafava-Bignami disease: serial changes in corpus callosum on MRI

Serial MRI findings of changes in corpus callosum lesions in two cases of Marchiafava-Bignami disease are presented. In both, MRI displayed diffuse swelling of the corpus callosum in the acute stage, thought to represent oedema and demyelination. In the chronic stage, in addition to atrophy of the corpus callosum with presumed focal necrosis, previously undescribed focal hypointensity on T2-weighted images, of unknown cause, was observed in the corpus callosum.

Prognostic assessment of tumor regression after external irradiation for cervical cancer

From February 1980 to December 1986, 428 cases of cervical cancer in Stage I through IVA were given curative radiation therapy at Chang Gung Memorial Hospital, Taipei. All of them received external irradiation and intracavitary brachytherapy. The degree of tumor regression was assessed immediately before the first intracavitary brachytherapy treatment. Patients were classified at this time as having (a) no gross residual tumor, or (b) gross residual tumor. Factors found to be associated with tumor regression by logistic regression analysis were stage, age and hemoglobin level. Patients with advanced cancer (Stage III, IVA), young age (less than 40 years), and low hemoglobin level (less than 10 g/dl) had a low incidence of no gross residual tumor. Five-year survival rate was 77% in patients with no gross residual tumor and 31% in patients with gross residual tumor (p less than 0.001). This significant difference held true even when one compared these two groups stage for stage; the difference was 77% versus 41% (p less than 0.001) in Stage II and 72% versus 28% (p less than 0.001) in Stage III. The local relapse rate was 59% in the gross residual tumor groups, significantly greater (p less than 0.001) than the 12% found in the no gross residual tumor group. It was concluded that patients whose tumors did not regress after external pelvic irradiation tended to recur after intracavitary brachytherapy, most often locally. This would justify a more aggressive treatment to improve local tumor control in this subset of high risk patients.

Effect of timing of cyclosporine administration on recovery from renal ischemia in rats

The effect of timing of cyclosporine administration on functional recovery from renal ischemia was studied in Sprague-Dawley rats. Animals were given cyclosporine and subjected to renal ischemia by temporarily occluding both the renal artery and vein. Our data demonstrate no significant difference in serum creatinine among rats subjected to renal ischemia, cyclosporine, or cyclosporine-vehicle cremophor EL administration, or the control group. On the other hand, renal ischemia in combination with cyclosporine resulted in rapid and marked deterioration in renal function with serum creatinine peaking on Day 2. The most significant rise was in rats that received cyclosporine 4 hr prior to induction of renal ischemia (4.7 +/- 0.5 mg/dl), followed by those that received cyclosporine 4 and 24 hr postischemia (2.8 +/- 0.5 and 3.2 +/- 0.7 mg/dl, respectively). Cyclosporine administration 24 hr prior to renal ischemia resulted in the least elevation of the serum creatinine (2.1 +/- 0.5 mg/dl) and the earliest return to the baseline value. Our data suggest that the timing of cyclosporine administration in rats subjected to renal ischemia influences the extent of renal injury and the subsequent recovery of renal function.

Renal allograft outcome in the cyclosporine era: comparison between intermediate-term failure and long-term survival

A single center experience of 160 cyclosporine-treated renal allografts that survived longer than 1 year was reviewed in an attempt to analyze the contribution of selected parameters to long-term survival. Sixty-one grafts were lost between 1 and 5 years, with the remaining functioning for longer than 5 years. Parameters with a significant influence on long-term survival included both quality of early graft function, with 13% of long-term survivors having delayed function, compared to 52% among the short-term survival group, and the incidence of acute rejection in the first year posttransplant (31% in long-term survivors compared to 63% in the short-term survival group). A marker for long-term survival (greater than 5 years) was a lower serum creatinine at 1 year (1.9 +/- 0.1 mg/dl, compared with 2.6 +/- 0.2 mg/dl in the short-term survival group). Recipient race, original renal disease, number of transplants and/or transfusions, panel reactive antibodies, and human leukocyte antigens matching did not appear to influence long-term outcome.

Retrospective analysis of posttransplantation diabetes mellitus in black renal allograft recipients

OBJECTIVE

To study the incidence, outcome, and possible etiopathogenic factors involved in posttransplantation diabetes mellitus in cyclosporine-treated black renal allograft recipients.

RESEARCH DESIGN AND METHODS

One hundred thirty-eight nondiabetic black renal transplant recipients whose grafts survived greater than 1 yr were studied retrospectively.

RESULTS

Twenty-eight (20.3%) patients developed posttransplantation diabetes mellitus, 46 and 75% were diagnosed by 6- and 12-mo posttransplantation, respectively, and 46% were insulin dependent. Diabetes was more frequently encountered in older recipients and recipients of cadaveric kidneys but was independent of sex, number of transplants, incidence of acute rejection, percentage of body weight gain, steroid or cyclosporine dose, and use of beta-blockers and/or diuretics. Renal function was similar in the diabetic group compared with the control group. Actuarial 5-yr graft survival was 82% in the diabetic cohort compared with 78% in the control group, with chronic rejection accounting for all graft losses within the diabetic group.

CONCLUSIONS

Twenty percent of black cyclosporine-treated renal allograft recipients developed diabetes mellitus in the posttransplantation period. However, its presence did not appear to influence intermediate-term graft or patient survival.