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Biomedical subjects

H Geiger

Publications and source records attributed to H Geiger.

At least 145 records · Page 8Linked to original sources
PubMed1973

C2 deficiency. Development of lupus erythematosus.

The study of serum from a patient with C2 deficiency is described. The patient had an episode of pneumococcal meningitis at 5 mo of age with seizures and transient hemiparesis and apparent purpuric skin lesions. He was first admitted to the University of Minnesota Hospitals at 10 yr of age following the discovery of proteinuria accidentally by his mother. Since then he has been admitted repeatedly to this hospital with numerous clinical findings including arthralgia, recurrent abdominal pain, proteinuria, membranous nephropathy, malar butterfly rash, seizures, personality aberrations, and recurrent fever. In June 1971, the patient developed positive DNA and DNP antibodies and positive LE cells. When the C profile was studied before and after recognition of lupus, C1q, C1s, and C4 dropped. C3 levels were elevated as were C5, C6, and C7, C3 proactivator had been reduced in the patient even before he developed lupus. Also because of a traumatic renal biopsy leading to a perirenal hematoma, he required surgery and a blood transfusion. 1 h after blood transfusion, a C2 titer of 23 hemolytic units was detected. Almost immediately levels of C3, C5, C6, and C7 dropped, C8 and C9 remained elevated. The addition of C2 from normal blood permitted dramatic activation of C3. These findings support the view that the rare deficiency in production of C2 predisposes to serious susceptibility to infection, vascular and mesenchymal disease as well as to renal disease and a lupus syndrome.

Antibodies↗
PubMed1973

The association of respiratory infection, recurrent hematuria, and focal glomerulonephritis with activation of the complement system in the cold.

The study of the activation of C3, C5, and C7 associated with the conversion of C3 in the serum of a 9-yr old girl after incubation at 0 degrees C for 6-8 h without utilization of C1, C4, and C2 is described. The patient has upper respiratory infections associated with recurrent gross hematuria, focal glomerulonephritis, and transient renal insufficiency. Histological lesions demonstrated the presence of B1c globulin IgA and properdin in the glomeruli. The activation of complement (C) in the cold requires the patient's IgA. Removal of IgA from the serum by immunoadsorption prevents activation and conversion of C3. Bactericidal and phagocytic activity is also impaired after incubation. C3 proactivator (C3PA) level is reduced before and after incubation. Properdin level drops after incubation. These findings suggest that the activation of C3 which is demonstrable in vitro may be a continuous process in vivo.

Child↗
PubMed1972

C1r deficiency: an inborn error associated with cutaneous and renal disease.

The studies of sera from two siblings with C1r deficiency are described. The brother (18 yr old) has shown clinical manifestations resembling lupus erythematosus for 5 yr, and the sister (24 yr old) has had arthralgia and recurrent episodes of rhinobronchitis since early childhood. Three siblings have died: one brother died at age 12 with symptoms similar to the disease of the male patient studied here, and two other siblings died in infancy, probably from infection. The low hemolytic C1 activity of the patients could be restored by the addition of purified C1r to their sera. Bactericidal activity and immune adherence were found to be impaired. When alternate pathways of the complement system were studied, both sera permitted activation of terminal components with endotoxin and cobra venom factor. These findings support the view that an alternate pathway for activation of the terminal portion of the complement cascade exists which does not utilize the conventional pathway operating through the usual early components.

Adolescent↗
PubMedDate not supplied

Influence of diuresis on enzymuria.

Urinary excretion of renal brush border enzymes may serve as an early marker of renal injury. However, the distinction between physiological and pathological levels remains controversial, since enzymuria is affected by physiological parameters. To clarify the influence of diuresis, we investigated the urinary excretion of alanine-aminopeptidase (AAP; EC 3.4.11.2) as function of diuretic state. 17 healthy volunteers of both sexes were subjected to protocols with sudden or prolonged water load preceded and followed by a thirst period. Urinary excretion of AAP was measured using an enzyme kinetic assay. As expected AAP excretion increased with urine flow, the increments diminished yielding an overall excretion pattern that resembled saturation kinetics. This function is described by a mathematical model. This model assumes, that AAP is released in proximal tubules at a constant rate and reabsorbed or inactivated in the distal tubule and collecting duct. Non-linear fits of the model equation to our data allowed two parameters, chi and mu, to be defined. Chi describes the rate of AAP release independent of urinary flow, and mu the ratio of distal tubular reabsorption or inactivation. If a substrate is not reabsorbed at all, mu approximates zero. Since mu fitted for AAP differed significantly from zero, this indicates reabsorption or inactivation of AAP in the distal nephron. Therefore, our study supports the theory of flow-dependent reabsorption or inactivation of AAP in the distal nephron.

Adult↗
PubMedDate not supplied

Transdifferentiation of distal but not proximal tubular epithelial cells from human kidney in culture.

Human renal proximal and distal (thick ascending limb and early distal convoluted tubule) epithelial cells have been isolated according to their specific antigen expression. The cells were well characterized by flow cytometry, enzyme cytochemistry and electron microscopy and cultured for up to 3 months. Cultured tubular cells coexpressed cytokeratin and vimentin as intermediate filament proteins. While primary isolated cells, proximal as well as distal, revealed the phenotypic characteristics of their nephron origin, cultured distal cells showed the tendency to dedifferentiate/transdifferentiate. Distal cells lost their characteristic expression of Tamm-Horsfall glycoprotein and started de novo expression of the proximal marker proteins aminopeptidase M, gamma-glutamyl transferase and dipeptidyl peptidase IV. The expression of these antigens by distal cells could be shown by flow-cytometric analysis and fluorescence microscopy. Enzyme activity assays revealed the activity of aminopeptidase M, gamma-glutamyl transferase and dipeptidyl peptidase IV, but not of the proximal marker enzyme alkaline phosphatase. This antigenic shift could not be prevented in different culture media, and the original phenotype could not be restored. Cultured cells displayed characteristic hormonal stimulation patterns indicative of their proximal and distal origins, as shown by activation of adenylate cyclase by different peptide hormones. These results indicate that distal tubular cells possibly transdifferentiate to a more proximal phenotype in view of loss of the distal marker enzyme Tamm-Horsfall protein and de novo expression of proximal marker enzymes like dipeptidyl peptidase IV and aminopeptidase M.

Alkaline Phosphatase↗