De Novo Membranous Glomerulonephritis

Abstract Context.—Recurrent and de novo glomerulonephritis is an important cause of renal allograft failure, but estimates of its prevalence vary widely. One reason for such variability is the inconsistency with which electron microscopy and immunofluorescence are used in assessing renal allograft biopsies. Objective.—To determine the prevalence of immune-complex deposits in all renal allograft biopsies performed during a 1-year period and to correlate their presence with clinical data. Design.—Our center accessioned a total of 118 renal allograft biopsies during 1 year from 88 patients. All biopsies were examined by both electron microscopy and immunofluorescence in addition to conventional light microscopy. Patient and donor characteristics were obtained as well as follow-up data for a minimum of 26 months after the index biopsy. Results.—Eight cases of immunoglobulin (Ig) A nephropathy were found (recurrent in 7 and de novo in 1). There were 9 instances of what we designate “IgM-positive immune deposits” without specific features of a recognized glomerulonephritis. To the best of our knowledge, the latter has not hitherto been described and may be part of a heterogeneous group of glomerulopathies. Other unexpected findings included de novo fibrillary glomerulonephritis and de novo membranous glomerulonephritis, the latter occurring at 3 months after engraftment. Conclusions.—A high proportion (19.5%) of unselected renal allograft biopsies show immune-complex deposits both with and without a recognized glomerulopathy. These require both electron microscopy and immunofluorescence for detection. IgM-positive deposits of uncertain etiology are relatively frequent.

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The Morphology of the Rat Kidney Following Folic Acid Administration

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100067996 ◽

1970 ◽

Vol 28 ◽

pp. 200-201

Author(s):

Aline Byrnes ◽

Elsa E. Ramos ◽

Minoru Suzuki ◽

E.D. Mayfield

Keyword(s):

Folic Acid ◽

De Novo ◽

Specific Activity ◽

Rat Kidney ◽

Present Report ◽

Intracellular Localization ◽

Male Rats ◽

Renal Hypertrophy ◽

Electron Microscopic ◽

Biochemical Alterations

Renal hypertrophy was induced in 100 g male rats by the injection of 250 mg folic acid (FA) dissolved in 0.3 M NaHCO3/kg body weight (i.v.). Preliminary studies of the biochemical alterations in ribonucleic acid (RNA) metabolism of the renal tissue have been reported recently (1). They are: RNA content and concentration, orotic acid-c14 incorporation into RNA and acid soluble nucleotide pool, intracellular localization of the newly synthesized RNA, and the specific activity of enzymes of the de novo pyrimidine biosynthesis pathway. The present report describes the light and electron microscopic observations in these animals. For light microscopy, kidney slices were fixed in formalin, embedded, sectioned, and stained with H & E and PAS.

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Early ossicle growth in the regenerating disc of a brittle star

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100169559 ◽

1994 ◽

Vol 52 ◽

pp. 364-365

Author(s):

M. Shlepr ◽

R. L. Turner

Keyword(s):

Cell Membrane ◽

Light Microscopy ◽

De Novo ◽

Current Model ◽

Syncytium Formation ◽

Brittle Star ◽

Intracellular Location ◽

Limited Volume ◽

Tissue Calcification

Calcification in the echinoderms occurs within a limited-volume cavity enclosed by cytoplasmic extensions of the mineral depositing cells, the sclerocytes. The current model of this process maintains that the sheath formed from these cytoplasmic extensions is syncytial. Prior studies indicate that syncytium formation might be dependent on sclerocyte density and not required for calcification. This model further envisions that ossicles formed de novo nucleate and grow intracellularly until the ossicle effectively outgrows the vacuole. Continued ossicle growth occurs within the sheath but external to the cell membrane. The initial intracellular location has been confirmed only for elements of the echinoid tooth.The regenerating aboral disc integument of ophiophragmus filograneus was used to test the current echinoderm calcification model. This tissue is free of calcite fragments, thus avoiding questions of cellular engulfment, and ossicles are formed de novo. The tissue calcification pattern was followed by light microscopy in both living and fixed preparations.

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