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J Knaack

Publications and source records attributed to J Knaack.

At least 19 recordsLinked to original sources
PubMed1994

[Urea sensor for the continuous ammonium-selective enzymatic process control of the artificial kidney].

Presented is a flow-through method for continuous ammonium-selective enzymatic monitoring of the artificial kidney by means of a bioelectrochemical urea electrode. The urea is converted in an enzyme membrane by covalently bound urease and the ammonium ions are detected by a Nonactin-PVC-membrane. In addition to detailed data from the oxygen-independent solid-state contact sensor, curves are obtained on-line from the patient during the haemodialysis session. The advantages of the method are described in detail. Furthermore, the urea sensor can be used for measurements in heparinized blood.

Anti-Bacterial Agents↗
PubMed1985

The role of azathioprine reduction in late renal allograft failure.

A group of 123 patients who had functioning renal transplants for more than 5 years were studied to discover whether prolonged reduction of azathioprine could predispose to late allograft failure. From the point of entry into the study (5 years after transplantation), the 5-year cumulative graft survival among living-related-donor recipients was 91.7%, and among non-living-related-donor recipients it was 84.8%. The azathioprine dose was reduced in 21 patients, for medical reasons, below 100 mg/day for more than one year when serum creatinine was stable and less than 2 mg/dl. Eight patients subsequently required dialysis. In the control group of 35 patients (transplanted in the same years, with serum creatinine that was similar at the same time posttransplantation to that of those who had azathioprine reduced) only 1 patient required dialysis. The likelihood of dialysis was significantly greater in those who had azathioprine reduced compared with those who did not (chi 2 = 12.0, P less than 0.001). No patient who had azathioprine reduced because of low white cell counts or chronic hepatitis subsequently required dialysis. It was concluded that a prolonged reduction of the azathioprine dose may predispose to late allograft failure.

Adult↗
PubMed1984

Glomerular sclerosis in a renal isograft and identical twin donor. A family study.

Loss of renal mass has been associated with the development of glomerular sclerosis in animals and human beings. The pathophysiology of this renal injury is unknown, but glomerular sclerosis in animals can be aggravated or accelerated following exposure to nephrotoxic antibodies, puromycin aminoglycoside or renal irradiation. We describe here the outcome of the first renal transplant performed in the British Commonwealth. Glomerular sclerosis occurred in identical twins who were kidney donor and recipient, renal failure occurring 14 and 16 years after transplantation, respectively. Examination of these twins and all living immediate family members showed that six of the seven family members (both twins, their mother, and three sisters) had increased concentrations of circulating immune complexes, decreased total hemolytic complement, and low or borderline concentrations of C4. Only twins with single kidneys had detectable renal disease. Other preexisting causes of renal disease in these twins that would account for the glomerular sclerosis could not be identified. We suggest that a familial immune defect contributed to the development of glomerular sclerosis in these twins who were predisposed to renal disease due to loss of renal mass.

Adolescent↗
PubMed1984

The diagnostic and prognostic value of renal allograft biopsy.

We prospectively studied 89 patients to assess the diagnostic use of renal allograft biopsy in the first three months after transplantation. These biopsies were done in patients in whom diagnosis was not clear or clinical rejection was deemed to be severe. Clinical diagnosis at initial biopsy was compared with the morphological diagnosis. To determine if morphological data improved the prognostic usefulness of the clinical data, we performed multiple logistic regression relating clinical variables at initial biopsy and histological changes in the transplant to the outcome of 120 patients one year after biopsy. The clinical and morphological diagnosis differed in 41 of 89 patients (46%). Of 120 patients in the prognostic study, 35 returned to dialysis during the first year following transplantation. Using multiple logistic regression, a categorical variable that took into account both the serum creatinine and its rate of change before biopsy was the best clinical predictor of return to dialysis. Further increase in chi 2 occurred with type of donor, number of transfusions, and age. Using the clinical variables we produced an index, from 0 to 1 to predict outcome. Only 8 had index less than 0.2, of whom 7 returned to dialysis. The best morphological predictor of outcome was interstitial hemorrhage. Further increase in chi 2 was obtained with vascular endothelial proliferation, glomerular endothelial swelling, and glomerular necrosis. With an index derived from the morphological variables only 11 had index less than 0.2, of whom 9 returned to dialysis. Combining both clinical and morphological data, the best predictor of return to dialysis was interstitial hemorrhage, followed by creatinine, glomerular endothelial swelling, and type of donor. Using both clinical and morphological variables we produced another index to predict outcome. A group of 65 patients had index greater than 0.8, of whom 63 (94%) did not return to dialysis, and 18 patients had index less than 0.2, 17 of whom returned to dialysis. The remaining 12 patients in the dialysis group and 15 in the nondialysis group had indices greater than 0.2 less than 0.8. We conclude that a transplant biopsy yields important diagnostic and prognostic information. Unexpected diagnoses were made in 46% of cases. The addition of morphological data to the clinical data available at time of biopsy greatly improved the prediction of return to dialysis.

Biopsy↗
PubMed1981

Renal involvement in malignant histiocytosis. An immunoperoxidase marker study.

In two patients who had malignant histiocytosis, renal involvement was present at an early stage of their diseases and consisted clinically of proteinuria and renal failure. The associated renal lesion was characterized by a diffuse and global endocapillary hypercellularity of the glomeruli imputable to atypical cells occluding the capillary loops. Immunoglobulins were absent from this lesion. The atypical cells were positively identified by lysozyme immunoperoxidase study as malignant histiocytes. It is suggested that renal biopsy complemented by marker study could play a role in the diagnosis of malignant histiocytosis.

Aged↗
PubMed1979

Late hypertension following renal allotransplantation.

Post-transplant hypertension has been observed in 98 renal allograft recipients who had good renal function and whose follow-up was more than 15 months. The role of the original diseased kidneys as well as the role of the renal pressor system was studied with emphasis on late hypertension. Post-transplant hypertension was found to be a multifactorial phenomenon with frequency decreasing as a function of prolonged graft survival. Renal artery stenosis was an infrequent but significant cause of hypertension and was found in 10 of 29 arteriograms performed. Renin studies performed in 34 hypertensive patients and in a control group of 11 recipients showed that elevation of plasma renin activity and of plasma aldosterone level is frequent but difficult to interpret, particularly when a renal artery stenosis is observed. These investigations may be useful in recognizing the role of retained diseased kidneys in sustaining hypertension. Plasma aldosterone was found elevated in nearly all of the patients. The role of corticosteroids and the similarity of post-transplant hypertension, in some cases, with the one kidney model of experimental hypertension are discussed.

Adolescent↗
PubMed1978

Donor pretreatment in an unselected series of cadaver renal allografts.

In a single center, an unselected non-exclusion series of 78 consecutive cadaver renal allografts in 76 recipients was studied. Since 1971, using kidneys obtained from donors pretreated with large doses of cyclophosphamide and methylprednisolone, excellent clinical results with 2-year graft-survival of 70% 5-year graft survival of 66% have been obtained. The improvement in results is believed to be aided by the reduction in allograft immunogenicity due to short-term donor pretreatment. In this series, poor tissue-matching grades are notable, heavily transfused patients are few, 33 patients were high risk, and 43 patients were presensitized. In spite of these negative selection factors, the results obtained in this pretreated series, with 18% of graft losses due to rejection, are superior to those obtained in patients who did not receive pretreated allografts during the same time period, with 34% of graft losses due to rejection, and 2-year and 5-year graft survivals of 57% and 53%, respectively.

Adolescent↗
PubMed1976

Giant cell carcinoma of the lung. A light and electron microscopic study.

Three cases of giant cell carcinoma of lung and six other lung carcinomas with large atypical cell formation were studied by both light and electron microscopy. The giant cell carcinomas showed unique light and electron microscopic features, whereas large atypical cells from other lung carcinomas usually retained some ultrastructural characteristics of their cellular origin. The giant cell carcinoma is characterized by abundant mitochondria, a concentric whorl of tonofilament-like fibrils, and aggregates of several pairs of centrioles. The "phagocytic activity" of the giant cell carcinoma is more likely attributable to the so-called tumor cell-tumor cell or leukocyte-tumor cell emperipolesis. Giant cell carcinoma of lung may originate from a primitive multipotential cell in the distal bronchiole or be associated with a squamous, glandular, or clear cell pattern. Whether in pure or mixed form, this tumor should still be considered a specific entity because of its unique light and electron microscopic features and the fulminant clinical course it follows despite rate reported exceptions.

Adenocarcinoma, Bronchiolo-Alveolar↗
PubMed1976

Nonessential role of neutrophils as mediators of hyperacute cardiac allograft rejection in the rat.

The presence of neutrophils within the graft has been widely emphasized as a characteristic feature of hyperacute rejection, and analogies have been drawn to the Arthus reaction, in which neutrophils are essential mediators of tissue damage. To evaluate the role of neutrophils as mediators of graft destruction in hyperacute rejection, we studied a series of 16 heterotopic ACT strain rat cardiac allografts in skin-presenitized Lewis strain recipients, all of which recieved prior treatment with cyclophosphamide and methotrexate or heterologous rabbit antirat polymorphonuclear globulin. Fourteen recipients showed significant depression in levels of circulating neutrophils prior to transplant, and neutrophils were not detected in 13 allogrates at the time of functional rejection. There was no abrogation of hyperacute rejection in this series and the characteristic pattern of vacular and myocardial damage was not altered by the absence of neutrophils from the graft. Although the possibility that neutrophil-derived agents may contribute to late graft destruction cannot be excluded, this study has shown that neutrophils are neither essential nor specific participants in hyperacute allograft rejection in this model.

Animals↗
PubMed1976

[Results of television microscopy utilization in spermatology].

The use of television microscopy in insemination laboratories was tested by VEB Studio-technik on two insemination stations of the GDR. A transistorised remote-observation system is described as a tool providing a universal range of applications for long-time no-maintenance operation of selected microscopes. The system was found to add to the accuracy and objective value of optical microscopy for spermatological studies. TV microscopy also will improve job conditions for the personnel involved.

Animals↗
PubMed1975

Extensive intraglomerular fibrin deposition after renal transplantation: recovery without anticoagulation.

Acute renal failure developed in a 55-year-old man 6 days after he had received a cadaver renal allograft. This was associated with thrombocytopenia. Extensive intraglomerular fibrin deposition was seen in a renal biopsy specimen. He was treated with corticosteroids, azathioprine, cyclophosphamide and hemodialysis with regional heparinization but not with systemic anticoagulation. This was followed by complete recovery of both renal function and histologic damage despite the fact that he did not receive anticoagulant therapy. This suggests that treatment with anticoagulants may not be necessary for all patients with intraglomerular deposits of fibrin.

Acute Kidney Injury↗
PubMed1975

Antilymphocyte globulin in renal transplantation: Nephrotic syndrome and infection as possible complications.

During a two-year period, nine patients received equine antilymphocyte globulin (ALG) as part of their immunosuppressive therapy following cadaver renal transplantation. Of these, three patients (33%) developed nephrotic syndrome. A fourth patient had proteinuria greater than 3 gm/24 hr not attributable to recurrent disease or rejection. Of 32 other patients with cadaver renal allografts done during the same time, none had nephrotic syndrome and two (6%) had proteinuria greater than 3 gm/24 hr, both with biopsy evidence of rejection. This suggests an association between ALG therapy and risk for developing nephrotic syndrome, but the mechanism is not clear and deserves further investigation. During the first three months following transplantation, the nine patients treated with ALG had 20 infections, which seems to be more per patient than in our other transplant recipients.

Adolescent↗