Biomedical subjects

Jeffrey R Henegar

Publications and source records attributed to Jeffrey R Henegar.

4 recordsLinked to original sources

PubMed2003

Glomerular calcification in hypercalcemic nephropathy.

Hypercalcemic nephropathy has been classified as a tubulointerstitial renal disease. The presence of glomerular pathologic findings attributable to hypercalcemia has been observed in only a few patients and therefore has been considered an unusual finding. In the current study, calcium deposition within glomeruli was investigated in 2 patients with extreme elevations in serum calcium levels and hypercalcemic nephropathy. The study material consisted of a renal biopsy specimen from a 31-year-old woman (patient 1) who had T-cell lymphoma/leukemia and a serum calcium level of 20.2 mg/dL (5.0 mmol/L) and autopsy kidney specimens from a 19-year-old woman (patient 2) who was being evaluated for primary hyperparathyroidism and a calcium level of 18.4 mg/dL (4.6 mmol/L). The renal biopsy specimen for patient 1 exhibited calcium deposits present in the glomerular capillary basement membranes, where they were associated with segmental sclerosing lesions (21% of glomeruli). Nine percent of the cortical tubules contained calcifications. In patient 2, calcium was found in the mesangial areas in 95% of glomeruli, filling the Bowman space in 7% of glomeruli, or associated with capillary basement membranes and segmental sclerosing lesions (12% of glomeruli). Fifteen percent of cortical tubules, 4% of outer medullary tubules, and 40% of inner medullary tubules were calcified. In neither case was there immunofluorescence or electron microscopic evidence of primary glomerular disease. Thus, glomerular calcification may exceed that occurring in the cortical and outer medullary tubules and may play a significant role in the loss of renal function in hypercalcemic nephropathy. Glomerular calcinosis may also be recognized as an additional cause of segmental glomerulosclerosis and nephrotic range proteinuria in patients with extremely high levels of serum calcium.

Adult↗

PubMed2002

Cytochrome P450 2B1 mediates oxidant injury in puromycin-induced nephrotic syndrome.

BACKGROUND: Reactive oxygen metabolites (ROM) are important mediators of puromycin aminonucleoside (PAN) induced minimal change nephrotic syndrome (NS) in rats. We have recently shown that cytochrome P450 (CYP) is a significant source of catalytic iron in this model of glomerular injury. The current study was designed to identify the CYP isozyme(s) in the rat glomeruli and explore the role of the specific isozyme(s) in PAN-induced minimal change NS. METHODS: NS was induced in rats by a single intravenous injection of PAN. Animals were sacrificed at different time points for variety of biochemical assays including Western blot, immunohistochemistry and reverse transcription-polymerase chain reaction (RT-PCR). Ultrastructural histochemistry was utilized to study hydrogen peroxide (H2O2) generation in the kidney. RESULTS: Several CYP isozymes were tested and CYP2B1 was localized exclusively in the rat glomeruli but not in the tubules. Treatment with PAN resulted in the generation of H2O2 in the glomerular basement membrane with significant loss of CYP2B1 content accompanied by a marked increase in the catalytic iron. CYP2B1 inhibitors cimetidine and piperine significantly reduced H2O2 generation, and prevented the loss of CYP2B1 content and the increase in the catalytic iron. CYP2B1 inhibitors also provided significant protection against PAN induced proteinuria. The induction of heme oxygenase and ferritin also was observed in the glomeruli in PAN-treated rats. Both cimetidine and piperine reduced the up-regulation of these proteins. CONCLUSION: Our data indicate that CYP2B1 plays an important role in PAN induced NS by serving as a site for ROM generation and a significant source of catalytic iron.

Animals↗

PubMed2002

Apoptosis in the left ventricle of chronic volume overload causes endocardial endothelial dysfunction in rats.

The hypothesis is that chronic increases in left ventricular (LV) load induce oxidative stress and latent matrix metalloproteinase (MMP) is activated, allowing the heart to dilate in the absence of endothelial nitric oxide (NO) and thereby reduce filling pressure. To create volume overload, an arteriovenous (A-V) fistula was placed in male Sprague-Dawley rats. To decrease oxidative stress and apoptosis, 0.08 mg/ml nicotinamide (Nic) was administered in drinking water 2 days before surgery. The rats were divided into the following groups: 1) A-V fistula, 2) A-V fistula + Nic, 3) sham operated, 4) sham + Nic, and 5) control (unoperated); n = 6 rats/group. After 4 wk, hemodynamic parameters were measured in anesthetized rats. The heart was removed and weighed, and LV tissue homogeneates were prepared. A-V fistula caused an increase in heart weight, lung weight, and end-diastolic pressure compared with the sham group. The levels of malondialdehyde (MDA; a marker of oxidative stress) was 6.60 +/- 0.23 ng/mg protein and NO was 6.87 +/- 1.21 nmol/l in the LV of A-V fistula rats by spectrophometry. Nic treatment increased NO to 13.88 +/- 2.5 nmol/l and decreased MDA to 3.54 +/- 0.34 ng/mg protein (P = 0.005). Zymographic levels of MMP-2 were increased, as were protein levels of nitrotyrosine and collagen fragments by Western blot analysis. The inhibition of oxidative stress by Nic decreased nitrotyrosine content and MMP activity. The levels of tissue inhibitor of metalloproteinase-4 mRNA were decreased in A-V fistula rats and increased in A-V fistula rats treated with Nic by Northern blot analysis. TdT-mediated dUTP nick-end labeling-positive cells were increased in A-V fistula rats and decreased in fistula rats treated with Nic. Acetylcholine and nitroprusside responses in cardiac rings prepared from the above groups of rats suggest impaired endothelial-dependent cardiac relaxation. Treatment with Nic improves cardiac relaxation. The results suggest that an increase in the oxidative stress and generation of nitrotyrosine are, in part, responsible for the activation of metalloproteinase and decreased endocardial endothelial function in chronic LV volume overload.

Animals↗

PubMed2001

Functional and structural changes in the kidney in the early stages of obesity.

The purpose of this study was to examine the histologic and functional changes that occur in the kidney in the early stages of obesity caused by a high-fat diet. Lean dogs (n = 8) were fed a standard kennel ration, and obese dogs (n = 8) were fed the standard kennel ration plus a supplement of cooked beef fat each day for 7 to 9 wk or 24 wk. Body weights were 58 +/- 5% greater and kidney weights were 31 +/- 7% greater in obese dogs, compared with the average values for lean dogs. Plasma renin activity and insulin concentrations were both 2.3-fold greater in obese dogs, compared with lean dogs. Obesity was associated with a mean arterial pressure increase of 12 +/- 3 mmHg, a 38 +/- 6% greater GFR, and a 61 +/- 7% higher renal plasma flow, compared with lean dogs. The glomerular Bowman's space area was significantly greater (+41 +/- 7%) in dogs fed the high-fat diet, compared with lean animals, mainly because of expansion of Bowman's capsule (+22 +/- 7%). There was also increased mesangial matrix and thickening of the glomerular and tubular basement membranes and the number of dividing cells (proliferating cell nuclear antigen-stained) per glomerulus was 36 +/- 8% greater in obese dogs, compared with lean dogs. There was also a trend for glomerular transforming growth factor-beta1 expression, as estimated by semiquantitative immunohistochemical analysis, to be elevated with the high-fat diet. Therefore, a high-fat diet caused increased arterial pressure, hyperinsulinemia, activation of the renin-angiotensin system, glomerular hyperfiltration, and structural changes in the kidney that may be the precursors of more severe glomerular injury associated with prolonged obesity.

Analysis of Variance↗