Peter M. Burkholder

Cadmium, a metallic inhibitor of antibody-mediated immunity in mice.

Chronic administration of cadmium chloride to B10-A-2R mice was discovered to severely depress the numbers and to delay the onset of appearance of splenic IgG and IgM plaque-forming cells (PFC) following injection of sheep erythrocytes. A recovery period of at least 1 month following cessation of administration of CdCl2 resulted in no increase in IgM PFC and only a minimal increase in IgG PFC. An apparent cadmium-induced splenomegaly was also noted in the intoxicated mice. Application of immune adherence and rosetting techniques as well as immunofluorescence to study the cellular morphology of these spleens indicated that the cell type most responsible for the increased spleen size had Fc and complement receptors as well as surface or cytoplasmic immunoglobulins. Populations of polymorphs and macrophages were not found to significantly contribute to the hyperplasia observed.

Ultrastructural changes in renal proximal tubules after chronic organic and inorganic mercury intoxication

Adult male rats were intoxicated daily with CH/sub 3/HgCl and HgCl/sub 2/ (1.0 mg/kg BW). Kidneys were sampled for electron microscopic and histochemical evaluation as well as neutron activation analysis between 1 day and 6 weeks of the experimental period. Ultrastructural changes were confined primarily to the pars recta segment of proximal tubules. HgCl/sub 2/ induced epithelial changes, observed at 5 days, consisted of apical vacuolation, mitochondrial swelling with dilation of cristae and calcinosis. Marked increase in lysosomal profiles, formation of membranous cytosomes and isolated cellular necrosis were observed afer 14-21 days of CH/sub 3/HgCl intoxication. Electron microscopic histochemical studies demonstrated mercury within mitochondria, lysosomes, microbodies, cytomembranous profiles and on cellular membrane structures. Neutron activation analysis demonstrated highest kidney total mercury levels after 5 days (HgCL/sub 2/) and 6 weeks (CH/sub 3/HgCl) intoxication.

An ultrastructural study on the blood-brain barrier dysfunction following mercury intoxication.

SummaryMethyl mercuric chloride (CH3HgCl) was administered in a single intraperitoneal injection to adult male rats at a dosage of 10 mg/kg body weight. Horseradish peroxidase was systemically injected into these animals at various time intervals following methyl mercury administration. Horseradish peroxidase activity as demonstrated by 3,3′-diaminobenzidene conjugation was used as a tracer to study blood-brain barrier dysfunction induced by methyl mercury. Permeation of tracer into the parenchyma of the central nervous system was observed ultrastructurally as early as 4–6 hrs following methyl mercury administration. Examination of capillary regions in the calcarine cortex and cerebellum at this time also revealed many endothelial cells with mitochondrial injury, increased pinocytotic transport of tracer, and in several instances, widening of lateral leaflet spaces without disruption of tight junctions. 6 hrs after the intoxication, many astrocytic end-feet abutting these injured capillaries displayed swelling and tracer accumulation. Horseradish peroxidase activity could be localized within neuronal and glial elements after 10–12 hrs of methyl mercury treatment. A newly developed electron microscopic histochemical technique utilizing an ammonium sulfide reaction was also employed to study the distribution of mercury within the blood-brain barrier structures. Localization of mercury corresponded with observed sites of cellular injury and tracer extravasation. It is believed that the observed blood-brain barrier dysfunction was due to the impairment of endothelial cells and astrocytic end-feet by mercury ions.

Recurrent Membranoproliferative Glomerulonephritis with Glomerular Properdin Deposition in Allografts

Abstract Two children with renal allografts developed membranoproliferative glomerulonephritis that was histopathologically similar to their original disease. Recurrent disease was diagnosed in bio...

Focal sclerosing glomerulonephropathy with hyalinosis: A clinical and pathologic analysis of the disease in children

A retrospective clinicopathologic study was made of 17 children with focal sclerosing glomerulonephropathy with segmental hyalinosis (FSGNH). Renal morphologic changes include segmental glomerular sclerosis with local hyaline, eosinophilic deposits. Segmental glomerular deposits of IgM, IgG, C3, and C4 were commonly observed. Ultrastructural evaluation revealed small paramesangial as well as large and small local subendothelial glomerular capillary electrodense deposits. Inital symptoms were mixed nephritic/nephrotic manifestations or proteinuria. Serum B1C was normal. Persistent hypertension and renal failure occurred early. Corticosteroid therapy was of no apparent, benefit. Five patients with serial renal biopsies showed histologic progression from minimal glomerular alterations that would have been interpreted as minimalchange glomerulonephropathy to FSGNH and finally chronic glomerulonephritis. FSGNH appears to be a specific glomerulonephropathy that may initially present as steriod-resistant nephrotic syndrome with minimal glomerular alterations and progress to chronic end-stage glomerulonephritis.

Vesicoureteral reflux nephropathy Evidence for immunologically mediated glomerular injury

Abstract A retrospective clinicopathologic analysis was done on 8 patients with bilateral vesicoureteral reflux, bacteriuria, and renal failure. Although none of the patients had a history of glomerulonephritis, quantitative urinary protein excretion of the 6 patients examined exceeded 2.3 Gm. per day and was greater than 5.2 Gm. per day in 4. Examination of the resected kidneys revealed an interstitial nephritis consistent with chronic pyelonephritis along with significant degrees of glomerular sclerosis. In addition, a granular deposition of immunoglobulin M and complement was seen in glomeruli of all 5 cases examined by immunofluorescence microscopy, and 2 cases had subendothelial electron dense deposits along glomerular capillary walls. The heavy proteinuria along with the deposition of immunoglobulin M and complement along glomerular capillary walls suggests that the terminal renal disease associated with vesicoureteral reflux has a component of glomerular injury possibly related to immunologic mechanisms.

Inhibition of mixed leukocyte culture responses in cadmium-treated mice

Previous studies have documented inhibition of antibody-mediated immunity by exposure of experimental animals to heavy metals. To date, very little is known of possible effects of heavy metal ions on cellular-mediated immunity. The mixed leukocyte culture (MLC) assay was used in this study to evaluate the effects on lymphocyte blastogenic response of chronic exposure of mice to cadmium (2 mg CdCl2/kg body wt/day). Spleen cells from two strains of mice treated with CdCl2 were unable to respond as effectively as control normal spleen cells to stimulation with allogeneic leukocytes. Furthermore, X-irradiated splenocytes from the cadmium-stressed animals were less effective than splenocytes from control normal mice as stimulator cells in the MLC reaction. This comparative decrease in T-lymphocyte reactivity could not be attributed to loss of lymphocyte viability or to decrease in ability of lymphocytes from cadmium-treated animals to incorporate tritiated thymidine. Although spleen cells from cadmium-intoxicated mice responded poorly to stimulation with allogeneic leukocytes, they were capable of responding to a mitogenic stimulus. Possible explanations for these observations are discussed.

Pressure-flow relationships and pathological changes during renal preservation

The renal pedicle of one kidney from each of four dogs was ligated for one hour. The contralateral kidney served as a control. Both kidneys were removed and perfused using the “Belzer” technique. Pressure-flow relationships were determined and biopsy samples taken. The vasculature was then injected with silicone rubber. Perfusion resistance, vascular filling with silicone rubber and observations made by electron microscopy were compared.