Faculty Bibliography

We report the case of a 52 year old man with a history of insulin-requiring diabetes and hepatitis B with cirrhosis who received an orthotopic liver transplant. One year later he developed renal colic and was found to have a 3 mm stone at the left ureterovesical junction. Numerous other stones formed and infrared spectroscopy analysis demonstrated all to be composed of 100% uric acid. Urine collections demonstrated a low urine pH of 5.1 without hyperuricosuria. His stones were effectively prevented with potassium citrate therapy. Few incidence data are available for uric acid stone occurrence in solid organ recipients. Calcineurin inhibitors are thought to often cause hyperuricemia on the basis of decreased urate excretion. However, this effect would not be expected to cause hyperuricosuria nor uric acid stones. This class of drugs may also be associated with low urine pH, perhaps on the basis of hypoaldosteronism, but the contribution of such a syndrome to uric acid stone formation is not established

Amyloid-associated protein (AA)-type systemic amyloidosis has been referred to as secondary amyloidosis because it is secondary to an associated inflammatory condition. It is extremely rare in patients with non-Hodgkin's lymphoma (NHL). Here we report an autopsy case of follicular small cleaved cell lymphoma with focal large B-cell lymphoma transformation in association with systemic AA-type amyloidosis. Formalin-fixed, paraffin-embedded tissues from autopsy and the patient's previous surgical specimen were studied by Congo red stain; electron microscopy; and immunostaining with antibodies against AA protein, P component, and kappa and lambda light chains. There was a marked AA amyloid deposition in the glomeruli of both kidneys, the retroperitoneal lymphoma mass, the blood vessels, the adrenal glands, and the adipose tissues. The patient's previous surgical specimens were negative for amyloid. We propose that this patient's systemic AA-type amyloidosis developed along the course of his NHL

The occupational risks for nephrolithiasis have not been widely studied. The published literature focuses on exposure to heat stress and toxic substances, not on the equally important behavioral risk factor of limited water consumption over many years. Urologic morbidity has been associated with suppressing the need to drink or void under restrictive work environments; however, no such studies link work related behavioral change with the development of kidney stones. This case report is the first to associate a restrictive work environment with limited fluid consumption, resulting in the development of nephrolithiasis

Microorganisms may have a role in the pathogenesis and prevention of kidney stones. The subjects of this review include nanobacteria, Oxalobacter formigenes, and lactic acid bacteria. Not reviewed here is the well-described role of infections of the urinary tract with Proteus species and other urease-producing organisms associated with struvite stone formation. Nanobacteria have been proposed to be very small (0.08-0.5 nm), ubiquitous organisms that could play a role in stone formation. The theory is that nanobacteria can nucleate carbonate apatite on their surfaces and thereby provide the nidus for stone formation. However, their existence remains uncertain and many investigators are openly skeptical. Recent investigations suggest that they are artifacts, and not actually living organisms, but their proponents continue to study them. O. formigenes is an obligate anaerobe which may be important in the prevention of stone formation. Its sole substrate for generation of ATP is oxalate. It may thereby metabolize its human host's dietary oxalate and diminish intestinal absorption and subsequent urinary excretion of oxalate. There is evidence that the organism's absence, perhaps sometimes due to courses of antibiotics, may be a cause of hyperoxaluria and stone formation. In early investigations, patients not colonized with the organism can be recolonized. Urinary oxalate can be diminished by accompanying an oxalate-containing meal with the organism. One study demonstrated that a preparation of lactic acid bacteria successfully reduced urinary oxalate excretion in 6 patients with calcium oxalate stones and hyperoxaluria. The mechanism of this effect is uncertain since these bacteria lacked the gene possessed by O. formigenes which codes for that organism's oxalate uptake mechanism. The author is currently completing a small randomized controlled clinical trial with this preparation in calcium stone-forming patients with idiopathic hyperoxaluria

Fourteen hemodialysis patients were selected to receive once every other week darbepoetin alfa in substitution for weekly subcutaneously administered epoetin alfa. All patients included in the analysis were male veterans over the age of 18 on established and unchanging doses of subcutaneous erythropoietin alfa and on hemodialysis for at least 3 months. All patients had sufficient iron stores, defined as serum ferritin concentrations of greater than 100 mcg/L. Patients were converted to darbepoetin alfa using the manufacturer's conversion chart. Doses of darbepoetin alfa were adjusted to maintain a hemoglobin concentration greater than 11 to 12 g/dL and a hematocrit greater than 33% to 36%. Patients were followed for 4 months and evaluated for efficacy. Hemoglobin, hematocrit, and serum ferritin levels were measured at baseline and repeated every month. Among the 12 patients completing the study, 12 dose increases of darbepoetin alfa were needed. Switching these 12 patients from erythropoietin alfa to darbepoetin alfa was projected to increase acquisition cost by more than $36,000, assuming that these patients remained on their current doses of darbepoetin alfa for 1 year. The authors concluded that darbepoetin alfa should not be used in patients with anemia caused by chronic renal failure who require hemodialysis until further studies support this use