Renal adenomatosis

Adenomatosis is a rare lesion of unknown etiology, defined as multiple (usually 5 or more) adenomas in one kidney. A case of renal adenomatosis in a 68-year-old woman treated previously for urolithiasis, who underwent nephrectomy because of the nonfunctional left kidney is reported. Apart from multiple adenomas, numerous hyperplastic lesions involving single tubules were present in the resected kidney. Both adenomas and hyperplastic lesions exhibited the expression of alpha-methylacyl-coenzyme A racemase (AMACR). Renal adenomatosis is worth special attention, since renal papillary adenomas are suggested as precursor lesions of papillary renal cell carcinoma that show similar AMACR expression.

Origins of Isolated Tubule Microperfusion Methodology

Understanding of renal function has been facilitated by the technique of perfusion of isolated renal tubule segments in vitro. The basic technology originated in the Laboratory of Kidney and Electrolyte Metabolism of the National Institutes of Health in the early 1960s and then was expanded to apply a variety of analytical methods to single tubules.

Effect of furosemide on calcium and magnesium transport in the rat nephron

Superficial tubules were perfused in vivo to determine the effect of intraluminal furosemide on electrolyte transport in the loop of Henle and distal tubule of the rat with special reference to calcium and magnesium reabsorption. in vivo perfusion of single tubules allowed us the opportunity to investigate separate electrolyte transfers with altering the corticomedullary concentration gradient within the kidney. Intraluminal furosemide (3 X 10(-6) and 3 X 10(-5) M) resulted in proportionately greater calcium and magnesium inhibition relative to sodium and chloride in Henle's loop. Furosemide had little effect on transport function within the perfused superficial distal tubule. Distal calcium and magnesium reabsorption was dependent on their respective deliveries to this segment. Parathyroid hormone increased fractional calcium and magnesium reabsorption in Henle's loop and the distal tubule in the presence of intraluminal furosemide. These results are consistent with a luminal effect of furosemide in the loop of Henle that inhibits calcium and magnesium transport to a greater degree than sodium chloride. Intraluminal ethacrynic acid (10(-4) M) or its cysteine complex had no effect on electrolyte transport in the perfused rat nephron.

Determination of Na-K-ATPase activity in single segments of the mammalian nephron

A micromethod for the determination of Na-K-ATPase in discrete segments of nephrons from rabbit, rat, and mouse kidneys is described. To facilitate tubule microdissection, the kidneys were perfused with collagenase after it had been verified that collagenase had no effect on ATPase activity. Individual tubule segments were dissected under stereomicroscopic observation, exposed to a hypotonic environment followed by rapid freezing, and incubated in 1 microliter assay medium. Enzyme activity was determined by direct measurement of labeled inorganic phosphate release by the hydrolysis of [gamma-32P]ATP and was expressed as a function of tubule length. This method is technically simple enough to permit simultaneous measurement of the enzyme in large numbers of tubules and sufficiently sensitive to determine its activity in each region of the nephron. Correlation of Na-K-ATPase activity in single tubules with functional measurements obtained in the corresponding segment of the nephron with the perfused tubule or micropuncture techniques should help define the role of this enzyme in tubular ion transport.

THE MORPHOGENESIS OF BASAL BODIES AND ACCESSORY STRUCTURES OF THE CORTEX OF THE CILIATED PROTOZOAN TETRAHYMENA PYRIFORMIS

Dividing cells of Tetrahymena pyriformis were observed by transmission electron microscopy for signs of morphogenesis of cortical structures. The earliest stage of basal body development observed was of a short cylinder of nine single tubules connected by an internal cartwheel structure. This is set perpendicular to the mature basal body at its anterior proximal surface under the transverse microtubules and next to the basal microtubules. Sequential stages show that the single tubules become triplet tubules and that the "probasal bodies" then elongate and tilt toward the organism's surface while maintaining a constant distance of 75–100 mµ with the "parent." The new basal body after it is fully extended contacts the pellicle, and then assumes a parallel orientation with and moves anterior to the parent basal body. The electron-opaque core in the lumen of the basal body and accessory structures around its outer proximal surface appear after the developing basal body has elongated. These accessory structures associating with their counterparts from other basal bodies and with the longitudinal microtubules may play a role in the final positioning of basal bodies and thus in the maintenance of cortical patterns. Observations on a second sequence of basal body formation suggest that the oral anlage arises by multiple duplication of somatic basal bodies.