Optimised cantilever biosensor with piezoresistive read-out.

We present a cantilever-based biochemical sensor with piezoresistive read-out which has been optimised for measuring surface stress. The resistors and the electrical wiring on the chip are encapsulated in low-pressure chemical vapor deposition (LPCVD) silicon nitride, so that the chip is well suited for operation in liquids. The wiring is titanium silicide which-in contrast to conventional metal wiring-is compatible with the high-temperature LPCVD coating process.

Environmental sensors based on micromachined cantilevers with integrated read-out

An AFM probe with integrated piezoresistive read-out has been developed and applied as a cantilever-based environmental sensor. The probe has a built-in reference cantilever, which makes it possible to subtract background drift directly in the measurement. Moreover, the integrated read-out facilitates measurements in liquid. The probe has been successfully implemented in gaseous as well as in liquid experiments. For example, the probe has been used as an accurate and minute thermal sensor and as a humidity sensor. In liquid, the probe has been used to detect the presence of alcohol in water.

Erythropoietin deficiency in acute crescentic glomerulonephritis and in total bilateral renal cortical necrosis.

Six patients with acute renal failure, in five cases due to acute crescentic glomerulonephritis and in one case due to total bilateral renal cortical necrosis, were studied. All had serum erythropoietin (EPO) concentrations in the normal range, despite a relatively severe anaemia. Half-life and plasma clearance of intravenously injected recombinant human erythropoietin (rhEPO) were determined. The results indicate that the lack of compensatory increase in serum EPO to the anaemic stimulus is not due to increased catabolism, but to decreased synthesis of the renal hormone. Two patients were treated with rhEPO (Eprex). In marked contrast to untreated controls, both patients responded with vigorous reticulocytosis and normalization of haemoglobin levels while they were still in severe renal failure. These results are similar to our previous findings in patients with acute renal failure due to tubular necrosis. Under all three conditions the defective EPO synthesis is probably the dominant pathogenetic factor for the largely aregeneratory anaemia of prolonged cases, and for the sluggish restoration of red cell mass during recovery of renal function. It is concluded that defective synthesis of EPO is not only a permanent and irreversible feature of severe chronic renal failure, but that it is also present, usually in a transient and reversible form, in different types of acute renal failure.

Erythropoietin deficiency in acute tubular necrosis.

Serum erythropoietin (EPO) concentrations were markedly depressed relative to the degree of anaemia in 10 patients with acute tubular necrosis, and remained low long after restoration of excretory renal function as estimated by glomerular filtration rate. Evidence is presented that the low serum EPO level is due to defective synthesis and not to increased catabolism. It is suggested that the predominantly are generatory anaemia found in prolonged cases of acute tubular necrosis, and the slow restoration of red cell mass during recovery, are due to the deficient synthesis of EPO. A positive erythropoietic response in a therapeutic trial with recombinant human erythropoietin (rhEPO) appears to support this hypothesis.

Vital indication for erythropoietin in a chronic haemodialysis patient. A case report.

A markedly anaemic, haemodialysis patient with a mixed deficiency of erythropoietin (EPO) and iron developed a life-threatening worsening of anaemia during an episode of severe rectal bleeding. Despite frequently recurring episodes of considerable ischaemic cardiac pain, the patient's religious conviction did not permit blood transfusion. Consequently, combination therapy with both recombinant human EPO (rhEPO) and oral iron was instituted. In this haemodialysis patient, the vitally significant replacement therapy of rhEPO and iron was followed by a steady and uncomplicated restoration of subnormal hematocrit and complete disappearance of cardiac ischaemia.

Response to erythropoietin in anaemic haemodialysis patients.

An open non-randomized clinical trial with recombinant human erythropoietin (rhEpo) was conducted in 10 chronic haemodialysis patients with considerable iron overload. Pretreatment serum erythropoietin levels were significantly decreased for the degree of anaemia (22.0 +/- 7.6 mUnits (U) ml-1). Initially all patients received 120 U kg-1 of rhEpo intravenously three times a week and after a period of 45 days the haematocrit rose from 25 +/- 3 to 36 +/- 5. A reduced dose of 30 U kg-1 was then instituted which stabilized the haematocrit at this level. The development of anti-erythropoietin antibodies to rhEpo could not be demonstrated. Endogenous serum erythropoietin levels remained unchanged during therapy with rhEpo. The serum ferritin concentration, which was initially 3118 +/- 1556 micrograms l-1, was significantly reduced to 2203 +/- 1299 micrograms l-1 after an 80-d treatment period. The side-effects in three patients included the occasional sensation of increased body heat without fever. In one previously hypertensive patient the antihypertensive therapy had to be temporarily increased, but otherwise both the mean diastolic and systolic blood pressure remained constant during the observation period. No clotting of arteriovenous fistulas occurred.

Frequency of hepatic cysts in adult polycystic kidney disease.

The frequency of hepatic cysts in patients with adult polycystic kidney disease (APKD) is usually considered to average about 33%, but with great, and hitherto largely unexplained, variations between different studies. Sixty-six consecutive patients with APKD were all subjected to CT scanning of the liver and of the kidneys. In confirmation of one previous study, a clearcut correlation was found between age (= duration of disease) and the frequency of hepatic cysts. It was furthermore found that cysts in the liver, as opposed to cysts in the kidneys, continue to grow and appear de novo even after institution of renal replacement therapy.

Recipient lymphocyte sensitivity to methylprednisolone affects cadaver kidney graft survival.

In 42 recipients of mixed-lymphocyte-culture (MLC) incompatible cadaver kidneys and conventional immunosuppressive treatment (azathioprine and steroids) the concentrations of methylprednisolone suppressing the in-vitro response of pretransplant lymphocytes to phytohaemagglutinin by 50% (ED50) were determined. 1-year graft survival was significantly higher in 21 recipients with methylprednisolone ED50 values below the median than in 21 patients with higher than median ED50s (86% v 29%; p less than 0.0002). Thus, the steroid sensitivity of recipients strongly influences the survival of MLC-mismatched kidneys. In 42 transplant recipients treated with cyclosporin and steroids, the effect of steroid sensitivity was also apparent (1-year graft survival 76% and 57% for recipients with low and high ED50, respectively), though not significant. Determination of the sensitivity to steroids may be valuable in determining which recipients can be given HLA-DR-mismatched kidneys and may serve as a guideline for determining the dose of steroids to be used.

Volume changes in polycystic kidneys during chronic dialysis and after renal transplantation.

Renal volume was determined by repeated CT scanning in 26 patients with adult polycystic kidney disease after institution of replacement therapy for terminal renal failure. Thirteen patients, treated for an average period of 6.7 years (SD 3.4, range 1.1-13.7), had a functioning necrokidney graft at the close of the study and had been grafted for 80.8% (SD 18) of the total treatment time. They showed a reduction of renal volume averaging 1.07% (SD 0.89) per month. Thirteen patients, treated for an average period of 5.7 years (SD 3.3, range 1.2-12.2), were on dialysis at the close of the study. Four had been on dialysis only, 9 had carried one or more (rejected) necrokidney grafts for 22.8% (SD 25) of the total treatment time. Three of them showed a significant increase in renal volume, whereas ten showed a decrease. The average change of renal volume in the entire group was -0.28% (SD 1.36) per month, significantly smaller than in the transplanted patients (p less than 0.01). It is concluded that polycystic kidneys shrink after successful grafting, whereas volume changes vary on dialysis treatment.

The impact of HLA-DR compatibility on cadaver kidney graft survival in a prospective study with special emphasis on the quality of typing.

The survival data of 151 consecutive cadaver kidneys transplanted by the two transplantation centres of Copenhagen from September 1, 1980 to September 30, 1982 with an observation period of at least 3 months have been analyzed. The HLA-DR types could not be established in 4 out of 130 donors. In most of the analyses only the well-defined antigens DR1, 2, 3, 4, 5, 7, and w8 were included. Inclusions of the DRw6, w9, and w10 antigens in the matching did not change the results. The one-year graft survival (GS) was 72.1% for 97 HLA-DR compatible kidneys as compared to 41.4% for 49 incompatible kidneys (p = .0007); this difference remained highly significant when stratified for the recipient status of pretransfusion, risk, and age. Non-transfused recipients had a fairly good GS but had received significantly better matched kidneys than the remaining recipients. The transfusion "effect" became barely significant (p = .054) when stratified for DR. There was no significant influence of donor or recipient DRw6-type as defined in this study. The GS was not significantly influenced by HLA-A, B matching, recipient antibody status, B cell cross-matches, transplant, or donor centre. Special efforts were made to assign the HLA-DR phenotypes of the recipients and donors as accurately as possible. In 39 cases, there was a discrepancy between the result of the acute DR-typing of the donor and the final result based on subsequent typings. The acute DR match had no influence on GS in these recipients whereas the final match had a significant influence in the same group, which in a way comprise a randomized trial. In the total material, the acute DR match still showed an influence on GS, but the significance decreased by a factor 20. This illustrates how the quality of DR typing may influence the results of the analyses. The overall GS (62.5%) was significantly (p = .05) better in this series than that (48.2%) in our preceding series, but it is uncertain whether this is due to better matching alone.

Involution of polycystic kidneys during replacement therapy of terminal renal failure.

Total kidney volume, i.e. the combined volume of both kidneys (TKV), was determined by computerized tomography (CT scanning) during replacement therapy of terminal renal failure in 12 patients with adult polycystic kidney disease. Mean TKV was 2 090 (872-3437) cm3 in six of 11 patients with both kidneys in situ, treated for 44 (28-59) months, and 1 184 (308-2761) cm3 in five, treated for 97 (75-130) months. The difference is not statistically significant (0.1 greater than p greater than 0.05). Two patients, treated for 89 and 130 months, had a TKV of 308 and 408 cm3, respectively, i.e. almost equal to the normal (303 cm3 (SD 29)). Six patients, five with both kidneys in situ and one unilaterally nephrectomized, were examined with two CT scans at an interval of 31 (17-46) months and all showed a significant decrease in TKV, averaging 0.77 (0.49-1.09) % per month of treatment. It is concluded that polycystic kidneys undergo involution during replacement therapy, but the gradual shrinkage may be difficult to verify by single volumetric measurements in patients treated for varying periods due to the large interindividual variation in TKV in adult polycystic kidney disease.

Volume of polycystic kidneys during reduction of renal function.

Total renal volume was measured by CT scanning in 43 patients with the adult form of polycystic kidney disease whose 24h endogenous creatinine clearance ranged from 8 to 130 ml/min. The total volume of the 2 kidneys increased from 1,212 (SD +/- 411) cm3 in patients with normal renal function to 2,053 (SD +/-698) cm3 in patients with severely decreased function, as compared to 497 (SD +/- 58) cm3 in persons without evidence of renal disease. Despite progression of the disease, the mean difference in size between the 2 kidneys remained constant and was significant only in patients with well-preserved renal function. In 23 of the 43 patients hepatic cysts and in 2 patients pancreatic cysts were demonstrable by CT scanning.

HLA-DR typing in cadaver kidney donors and recipients in Copenhagen.

Among 224 cadaver kidney transplantations performed since Spring 1977, successful DR typing of both donor and recipient could be done in 149 cases. Assessment of DR match grade and clinical data was done independently. The minimum observation time was 3 months and the time of follow up was 1 December, 1980. There was an effect of DR matching which became significant when only 1. transplants were considered and high risk recipients (i.e. diabetics) excluded. Transfusions were of minor importance on graft survival and the difference was only obvious in the first year after transplantation. Matching for HLA-A, B antigen had no obvious effect on graft survival in this material.

MLC compatibility, HLA-D and DR typing in cadaver kidney transplantations.

During a period of one year, spleen lymphocytes from cadaver kidney donors were cryopreserved for later investigations. The HLA-D types of 33 donors and the corresponding 39 recipients were determined in six experiments and the reactivities of the lymphocytes of the individual recipients towards those of the donors were assayed in MLC. The MLC experiments included a sufficient number of unrelated responders and stimulators to allow an estimate of the specific MLC reactivity by the stabilized relative response. A strong and significant correlation was found between specifically low reactivity of recipient lymphocytes against donor lymphocytes and graft survival. A correlation was also found between HLA-D compatibility and graft survival. DR typing was performed on the same donor-recipient pairs. In sixteen cases the DR typing of the recipients was initially a technical failure but successful when repeated on cryopreserved lymphocytes. There was a significant correlation between HLA-DR compatibility and graft survival. HLA-A, B matching and pretransplant blood transfusion did not significantly affect graft survival in this material.

The effect of 1-alpha-hydroxycholecalciferol on the renal handling of phosphate in parathyroidectomized man.

In a previous investigation by our group it was suggested that the stimulating effect of 1-alpha-hydroxycholecalciferol (1-alpha-OH-D3) on the tubular reabsorption of phosphate is mediated via the parallel suppression of the parathyroid hormone (PTH). A direct effect of 1-alpha-OH-D3 on the renal tubule could however not be completely excluded. Therefore, the effect of 1-alpha-OH-D3 was studied in 5 totally parathyroidectomized patients, in whom concomitant suppression of PTH would not occur. TmP/GFR, i.e. the ratio between the maximal tubular reabsorption of phosphate (TmP) and the glomerular filtration rate (GFR), was used as an indicator of the renal handling of phosphate. Estimation of TmP/GFR was performed 1) when the patients were vitamin D depleted and hypocalcemic, and 2) after 14-27 days of treatment with 1-alpha-OH-D3 to obtain stable normocalcemia. In patients with absent parathyroid function, no effect of 1-alpha-OH-D3 on TmP/GFR could be demonstrated. It is therefore concluded that 1-alpha-OH-D3 exhbits no antiphosphaturic effect in the absence of PTH and that the previously demonstrated antiphosphaturic effect of 1-alpha-OH-D3 in man is mediated via a concomitant suppression of PTH.

Permanent withdrawal of prednisone in nekro-kidney transplantation.

Starting 2.5 (2.0-3.9) years after grafting prednisone (but not azathioprine) has been gradually reduced below the conventional maintenance dose of 10 mg per day in 43 and has up until now eventually been completely withdrawn in 23 out of 47 consecutive patients with a first nekro-kidney transplant, which was well functioning at 2 years after transplantation. There appeared to be an increased risk of rejection during reduction of prednisone from 10 to 2.5 mg per day, but 20 out of the 23 patients in whom prednisolone has by noe been completely withdrawn have maintained stable and normal graft function over an average period of 1.6 (0.1-3.0) years on zero prednisone.

Is renal osteodystrophy reversible?

In order to investigate the possible reversibility of renal osteodystrophy, eleven necrograft recipients were investigated six years after transplantation, when treatment with prednisone had been withdrawn for 1.5 years. Serum ionised calcium, phosphorus, alkaline phosphatases, PTH, skeletal radiography, Technetium polyphosphate (Tc-PP) bone scintigraphy and radial bone mineral content (BMC) were studied. Normal blood biochemistry, radiography and Tc-PP scintigraphy were found in nine (82%) of the patients, in contrast to the considerably higher frequency of abnormalities ordinarily found in haemodialysis patients. However, the radial BMC was significantly reduced (mean 13.5%) and identical with the BMC value in haemodialysis patients. We conclude that some regression of renal osteodystrophy may take place after a successful kidney transplantation, but that decreased mineralisation of the appendicular skeleton persists. Whether this latter finding is due to long-term steroid treatment or is an indicator of an irreversible component in renal osteodystrophy cannot be stated.

Long term survival and graft function after cadaver kidney transplantation.

During the period 1968-75 310 cadaver kidney transplantations were carried out; 261 first-time, 45 second-time and 4 third-time transplantations. Graft survival after 5 years was about 30% for both the first and the second transplant. Patient survival after 5 years was about 50%. No relationship could be found between match grade and graft survival whereas the patient survival was definitely better in the younger age groups. The major cause of graft loss was rejection, vascular and ureteral complications being less frequent. The main cause of lethal outcome was complications to the immunosuppressive therapy and to a lesser degree cardiovascular events and malignant disorders. Cadaver kidney transplantation is an acceptable treatment of chronical renal failure particularly in younger persons and in cases where dialysis treatment is difficult.