muramidase and Nephrosis

In previous studies, we have demonstrated that the low molecular weight protein lysozyme can be used as a renal-selective drug carrier for delivery of the angiotensin-converting enzyme (ACE) inhibitor captopril. Typically, such macromolecular drug-targeting preparations are administered intravenously. In the present study, we investigated the fate of captopril-lysozyme following subcutaneous administration, a convenient route for long-term treatment. The absorption from the subcutaneous injection site and renal uptake of lysozyme were determined by gamma scintigraphy in rats. Bioavailability, renal accumulation, and stability of the captopril-lysozyme conjugate were evaluated by high performance liquid chromatography analysis and by ACE activity measurements. Lysozyme was absorbed gradually and completely from the subcutaneous injection site within 24 h and accumulated specifically in kidneys. After subcutaneous injection of the captopril-lysozyme conjugate, higher renal captopril levels and lower captopril-lysozyme levels in urine indicated the improved renal accumulation in comparison with intravenous administration of the conjugate, as well as its stability at the injection site. After both treatments, captopril-lysozyme conjugate effectuated renal ACE inhibition, whereas plasma ACE was not inhibited. In conclusion, our results demonstrate that we can use the subcutaneous route to administer drug delivery preparations like the captopril-lysozyme conjugate.

Topics: Angiotensin-Converting Enzyme Inhibitors; Animals; Antibiotics, Antineoplastic; Captopril; Doxorubicin; Drug Delivery Systems; Injections, Subcutaneous; Kidney; Male; Muramidase; Nephrosis; Proteinuria; Radionuclide Imaging; Radiopharmaceuticals; Rats; Rats, Wistar

Puromycin aminonucleoside nephrosis (PAN) results in a marked increase in the fractional clearance of albumin. The increase in the fractional clearance of [(3)H]albumin to approximately 0.045, as measured both in vivo and in the isolated perfused rat kidney (IPK) with PAN, occurs without an accompanying equivalent increase in glomerular capillary wall size selectivity as previously measured with dextrans. This is very similar to the marked increase in albuminuria seen with kidneys treated with inhibitors of endocytosis by the tubular epithelium, particularly lysine (T. M. Osicka, L. M. Pratt, and W. D. Comper. Nephrology 2: 199-212, 1996). The similarity is further established that, like in the presence of lysine, [(3)H]albumin excreted in urine from rats with PAN is essentially intact whereas, in both in vivo and IPK control experiments, excreted [(3)H]albumin is heavily degraded. The same observations have also been made for (3)H-labeled anionic horseradish peroxidase. These observations suggest that the significant albuminuria that occurs in PAN is primarily post-glomerular basement membrane in origin.

Topics: Albuminuria; Animals; Horseradish Peroxidase; Kidney; Male; Metabolic Clearance Rate; Muramidase; Nephrosis; Puromycin Aminonucleoside; Rats; Rats, Sprague-Dawley

The hydroxyl radical scavengers dimethylthiourea (DMTU), sodium benzoate, and dimethylsulfoxide (DMSO) were administered to rats before doxorubicin hydrochloride (ADR) (5 mg/kg, IV) to probe the role of free radicals in mediating proteinuria in doxorubicin hydrochloride nephrosis (AN). Because ADR stimulates free radical production, the role of renal glutathione was also evaluated; glutathione metabolism is involved in tissue detoxification processes. DMTU administration to rats with AN caused a significant (p less than 0.01) reduction in their proteinuria after 7 days (52.84 +/- 13.21 mg/24 hours) when they were compared with ADR controls (155.81 +/- 20.16 mg/24 hours). In similar fashion, their urine albumin excretion was also significantly reduced when compared with that of ADR controls (11.13 +/- 2.75 mg/24 hours vs 32.08 +/- 4.14 mg/24 hours; p less than 0.01). DMTU-treated rats also had significantly (p less than 0.001) reduced urinary protein and albumin excretion at 14 days when compared with rats that received ADR alone. The urinary excretion of lysozyme and N-acetyl-glucosaminidase, markers of renal tubular injury, were significantly increased after 7 or 14 days in rats with AN, despite DMTU treatment. Creatinine clearance was significantly reduced (p less than 0.05) in rats receiving ADR alone (0.223 +/- 0.011 ml/min/100 gm) when compared with that in normal controls (0.331 +/- 0.027 ml/min/100 gm) or DMTU-treated rats (0.289 +/- 0.035 ml/min/100 gm). Unlike DMTU, neither sodium benzoate nor DMSO reduced proteinuria in rats with AN.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Acetylglucosaminidase; Albuminuria; Animals; Benzoates; Benzoic Acid; Creatine; Dimethyl Sulfoxide; Disease Models, Animal; Doxorubicin; Free Radical Scavengers; Glomerular Filtration Rate; Glutathione; Hydroxides; Hydroxyl Radical; Injections, Intravenous; Kidney Cortex; Male; Muramidase; Nephrosis; Proteinuria; Rats; Rats, Inbred Strains; Thiourea

An immunoblotting technique was developed to detect human lysozyme and lysozyme complexes in body fluids. The unoccupied binding capacity of proteins was demonstrated by addition of surplus lysozyme. The sensitivity of immunoblotting to the free enzyme in human albumin solution was less than 5 ng. In serum and pleural fluid, part of exogenous lysozyme was bound to alpha 2-macroglobulin (alpha 2-M). At high concentrations of lysozyme in leukemic sera, part of the enzyme formed an endogenous alpha 2-M complex. On the other hand, the formation of alpha 2-M complexes with exogenous lysozyme was especially striking in sera from nephrotic patients with elevated alpha 2-M. The findings corroborate with previous reports on lysozyme binding to purified alpha 2-M in vitro and suggest that the binding is concentration-dependent with respect to both reaction partners. In vivo the mechanism may provide a pathway for extrarenal lysozyme catabolism medicated by reticuloendothelial cells. No other binding proteins were seen in the present study: lysozyme did not bind to serum immunoglobulins in 35 samples with an immunoglobulin paraprotein, three samples with polyclonally elevated gamma-globulins, 20 other patient sera and 10 normal sera. Neither did lysozyme bind to urinary proteins in five samples from patients with myeloic leukemias nor in 10 samples from myeloma patients with urinary excretion of a monoclonal immunoglobulin light chain.

Topics: alpha-Macroglobulins; Humans; Immunoblotting; Immunologic Deficiency Syndromes; Leukemia, Myeloid; Muramidase; Nephrosis; Pleura; Pleurisy

Topics: Animals; Anions; Basement Membrane; Binding Sites; Kidney Glomerulus; Male; Muramidase; Nephrosis; Puromycin Aminonucleoside; Rats; Time Factors

Perfusion of rat kidneys with polycations (protamine sulfate, poly-L-lysine), resulted in glomerular epithelial alterations very similar to those observed in proteinuric states, particularly rat aminonucleoside nephrosis. Such changes did not occur after exposure to neutral or anionic macromolecules (poly-DL-alanine, myoglobin, heparin, poly-L-glutamic acid and ovalbumin). Morphigenetic factors in the polycation-induced lesion included retraction and flattening of foot processes, narrowing of filtration slits, formation of occluding junctions between foot processes and cell swelling. The associated suppression of histochemically demonstrable glomerular polyanion suggested that neutralization of cell surface anionic sites was an important factor in the causation of the lesion, which was reversible by reperfusion with heparin. Observations by freeze-fracture confirmed the similarity of the polycation-induced lesion to the epithelial changes in rat aminonucleoside nephrosis. Following exposure to polycations there was also "staining" of anionic sites on epithelial and endothelial cell membranes and glomerular basement membrane. Reperfusion of protamine-treated kidneys with heparin resulted in restoration of previously suppressed colloidal iron staining and the formation of spherical, electron-dense (heparin-protamine) complexes within the glomerular filter.

Topics: Animals; Arginine; Female; Freeze Fracturing; Heparin; Iron; Kidney Glomerulus; Microscopy, Electron; Muramidase; Nephrosis; Peptides; Polyamines; Polylysine; Protamines; Rats; Staining and Labeling

Topics: Albuminuria; Animals; Chromatography, Gel; Chromatography, Ion Exchange; Fibrin; Fibrinogen; Glomerular Filtration Rate; Glomerulonephritis; Humans; Immunoelectrophoresis; Kidney Transplantation; Molecular Weight; Muramidase; Nephrosis; Plasminogen; Rabbits; Streptokinase; Transplantation, Homologous; Uremia

Topics: Alkaline Phosphatase; Animals; Aspartate Aminotransferases; Electrophoresis, Disc; Enzymes; Glomerulonephritis; Glucuronidase; Kidney; L-Lactate Dehydrogenase; Leucyl Aminopeptidase; Muramidase; Nephrosis; Nucleosides; Proteinuria; Rabbits; Rats; Rats, Inbred Strains; Toxins, Biological

Topics: Age Factors; Alkaline Phosphatase; Amylases; Aspartate Aminotransferases; Child; Child, Preschool; Electrophoresis, Disc; Enzymes; Glomerulonephritis; Glucuronidase; Humans; Infant; Infant, Newborn; L-Lactate Dehydrogenase; Leucyl Aminopeptidase; Muramidase; Nephrosis; Posture; Proteinuria

Topics: Animals; Chromates; Kidney; Kidney Tubules; Mercury; Muramidase; Nephrectomy; Nephrosis; Rats; Uranium