Enteric oxalate nephropathy in the renal allograft: an underrecognized complication of bariatric surgery.

Enteric hyperoxalosis is a recognized complication of bariatric surgery, with consequent oxalate nephropathy leading to chronic kidney disease and occasionally end-stage renal failure. In patients with prior gastrointestinal bypass surgery, renal allografts are also at risk of oxalate nephropathy. Further, transplant recipients may be exposed to additional causes of hyperoxalosis. We report two cases of renal allograft oxalate nephropathy in patients with remote histories of bariatric surgery. Conservative management led to improvement of graft function in one patient, while the other patient returned to dialysis. Interpretation of serologic, urine and biopsy studies is complicated by oxalate accumulation in chronic renal failure, and heightened excretion in the early posttransplant period. A high index of suspicion and careful clinicopathologic correlation on the part of transplant nephrologists and renal pathologists are required to recognize and treat allograft oxalate nephropathy. As the incidence of obesity and pretransplant bariatric surgery increases in the transplant population, allograft oxalate nephropathy is likely to be an increasing cause of allograft dysfunction.

Acute kidney injury with cryoglobulinemic peritubular neutrophilic capillaritis.

BACKGROUND: Neutrophil predominant capillaritis and interstitial inflammation is an uncommon renal biopsy finding, with a broad differential diagnosis. CASE: A 77-year-old woman presented with a complicated history including vasculitis, cryoglobulinemia, malaise, and systemic symptoms, which progressed to acute kidney injury. Renal biopsy demonstrated prominent neutrophilic capillaritis with interstitial inflammation, and fibrinoid deposits in medullary capillaries and interstitium. Glomeruli showed membranoproliferative glomerulonephritis, but no crescents or necrosis. DISCUSSION: We interpret the capillary and interstitial changes as evidence of cryoglobulin-associated vasculitis, and discuss the differential diagnosis of this uncommon histologic pattern of renal pathology, including other vasculitides, infection, ischemia-infarction, collagen vascular disease, and antibody-mediated allograft rejection, among others.

cis-diamminedichloroplatinum(II) nephrotoxicity: tubular function after rescue with sodium diethyldithiocarbamate in rats.

Sodium diethyldithiocarbamate (DDTC) administered following cis-diamminedichloroplatinum(II) (DDP) has been reported to attenuate structural renal damage and elevation of blood urea nitrogen in rats. Since DDP damages primarily proximal tubular epithelium in this species, we compared proximal tubular function, glomerular function, and histology in male Sprague-Dawley rats treated with DDP followed by either DDTC or 0.9% NaCl solution (NS) rescue. Male Sprague-Dawley rats received a single i.p. injection of DDP (7.5 mg/kg)-mannitol (75 mg/kg)-NaCl (67.5 mg/kg). Forty-five min later, rats were given i.p. injections of either DDTC (750 mg/kg) dissolved in 0.5 ml of NS (DDP + DDTC group; ten rats) or 0.5 ml NS (DDP + NS group; nine rats); additional rats received either DDTC only (DDTC group; six rats) or no treatment (untreated control group; six rats). All groups were sacrificed 5 days later by ether anesthesia and exsanguination. Compared to the untreated control group, the DDTC group had slightly lower mean blood urea nitrogen at sacrifice [12.5 +/- 0.5 (S.E.) versus 15.4 +/- 0.8 mg/dl; p less than 0.025 by unpaired Student's t test]; there was no difference in serum creatinine. The DDP + DDTC group had no diarrhea and no presacrifice deaths in contrast to diarrhea and three presacrifice deaths in the DDP + NS group. Blood urea nitrogen was also lower in the DDP + DDTC group at sacrifice (187 +/- 30 versus 383 +/- 39 mg/dl; p less than 0.005). However, weight loss and serum creatinine were not different. Structural acute tubular necrosis was marked in both DDP groups but was less severe in the DDP + DDTC group than in the DDP + NS group. Proximal tubular function was indexed by the uptake of the organic base N-[14C]methyl nicotinamide (NMN) and the organic acid p-aminohippurate in renal cortical slices incubated 90 min in Cross and Taggart medium. NMN uptake (expressed as slice to medium ratio) was slightly lower in the DDTC group than in untreated controls (4.1 +/- 0.2 versus 5.0 +/- 0.2; p less than 0.025). Marked depression of p-aminohippurate and NMN uptake occurred in both DDP + DDTC and DDP + NS groups. There was no difference in NMN uptake, but depression of p-aminohippurate uptake was slightly less severe in the DDP + DDTC group (5.3 +/- 0.7 versus 3.1 +/- 0.3; p less than 0.005). We conclude that DDTC rescue attenuates structural DDP injury in this animal model. DDP-mediated proximal tubular dysfunction was only marginally attenuated by DDTC; glomerular filtration rate, as indexed by serum creatinine, was not protected. DDTC attenuation of DDP toxicity may be mediated in part via reducing volume depletion due to DDP-associated diarrhea.

Chronic tubulointerstitial nephritis caused by recurrent myoglobinuria.

A 42-year-old man with McArdle's disease had numerous episodes of pigmenturia, but had only one proved episode of acute renal failure that required dialysis. A renal biopsy performed one month after complete recovery from that nephrotoxic event showed severe tubulointerstitial fibrosis. These findings suggest that, while acute renal failure may be an infrequent complication, repeated episodes of myoglobinuria may initiate subclinical nephrotoxic insults, resulting in chronic tubulointerstitial nephritis.

Herpes simplex type 1 hepatitis in renal transplantation.

Herpes simplex is a rare but usually fatal cause of acute hepatitis in adults. Most previously reported cases have occurred in debilitated or immunosuppressed patients. We report two additional fatal cases that occurred in renal transplant recipients. In case 1, there is evidence that the allograft may have been the initial nidus of infection. In case 2, dissemination from a genital infection occurred and failed to respond to vidarabine therapy that was started early in the clinical course. We also review the literature concerning previously reported cases of herpes hepatitis.

Evidence for hypothalamic control of the diurnal rhythms in prolactin and melatonin in the fetal sheep during late gestation.

We have investigated the effect of surgical disconnection of the fetal hypothalamus and pituitary (HPD) on generation of the daily rhythm in fetal plasma melatonin and PRL concentrations under long and short photoperiods. Fetal HPD or a sham operation was carried out at around 110 days gestation. Ewes carrying either HPD fetal sheep (n = 10) or intact fetal sheep (n = 12) were exposed to a long light (LL; 16 h of light and 8 h of darkness) or a short light (SL; 8 h of light and 16 h of darkness) regimen for the remainder of gestation. All ewes were subjected to a 24-h blood-sampling experiment (13 samples collected between 0900-0900 h the following day) between 135-140 days gestation, and fetal and maternal plasma melatonin and PRL concentrations were measured using specific RIAs. The hormonal data were analyzed using multifactorial analysis of variance and cosinor analysis. There was an increase in maternal melatonin concentrations during the dark phase in each lighting regimen in ewes carrying HPD or intact fetal sheep. In the SL regimen, there was also a significant increase in fetal melatonin concentrations during the dark phase in the HPD and intact groups. Under LL conditions, however, fetal melatonin concentrations were only consistently increased during the dark phase in the intact, not the HPD, group. The 24-h mean fetal plasma concentrations of PRL were significantly higher (P < 0.001) in both intact and HPD fetuses in the LL (intact, 111.0 +/- 22.0 pg/ml; HPD, 37.6 +/- 7.3 pg/ml) than in the SL regimen (intact, 37.8 +/- 18.4 pg/ml; HPD, 6.7 +/- 4.3 pg/ml). There was also a significant interaction (P < 0.001) between the effects of fetal surgical treatment and time of day on fetal PRL concentrations. In the intact group, fetal PRL concentrations were significantly higher (P < 0.05) at 1300 and 1700 h than between 0300-0700 h in both lighting conditions. Cosinor analysis also identified a significant rhythm in 8 of the 12 fetal PRL profiles in the intact group. In contrast, in the HPD group, there was no significant effect of time of day on fetal PRL in either the LL or SL regimen, and cosinor analysis only identified a significant rhythm in 2 of the 10 fetal PRL profiles in this group. We have, therefore, demonstrated that in the fetal sheep, HPD resulted in abolition of the diurnal melatonin rhythm under LL conditions and in the loss of the diurnal PRL rhythm under LL and SL conditions.(ABSTRACT TRUNCATED AT 400 WORDS)

Photoperiodic history and hypothalamic control of prolactin secretion before birth.

We investigated whether the fetal lamb can construct a photoperiodic history in utero. We measured the fetal PRL response to a 12-h photoperiod in intact fetal sheep and in fetal sheep after hypothalamo-pituitary disconnection (HPD), following exposure of the ewe to either a long (16 h L) or short (8 h L) photoperiod for 50 days in early pregnancy. Ewes were maintained on either a long light (LL, n = 20) or a short light (SL, n = 19) regimen from 57 days gestation until fetal HPD (pre-LL, n = 7; pre-SL, n = 7) or sham surgery (pre-LL, n = 13; pre-SL, n = 12) was performed at 99-113 days gestation. All ewes were housed in a 12-h photoperiod from surgery until 140 days gestation. In HPD fetal sheep previously exposed to SL, fetal PRL concentrations were significantly higher (P < 0.05) after 20 days in the 12-h L regimen than previously (0-5 days, 3.2 +/- 0.6 ng/ml; 21-25 days, 5.6 +/- 1.4 ng/ml). In the HPD fetal sheep previously exposed to LL, however, fetal PRL concentrations significantly decreased (P < 0.05) after 5 days exposure to the 12-h L regimen (6.7 +/- 2.9 ng/ml) and remained low throughout the remaining study period (31-35 days, 1.7 +/- 0.5 ng/ml). In contrast, in the sham group there was no effect of photoperiodic history on the gestational age profile of fetal PRL, and PRL concentrations increased significantly (F = 22.4, P < 0.001) in fetal sheep previously exposed to either SL or LL. Fetal PRL concentrations were significantly higher (P < 0.05) after 121 days gestation in the 12-h L regimen in all sham fetal sheep (<110 days, pre-SL 6.4 +/- 0.3 ng/ml, pre-LL 12.0 +/- 3.3 ng/ml; 121-125 days, pre-SL 20.0 +/- 3.9 ng/ml, pre-LL 25.9 +/- 4.4 ng/ml). TRH (50 microg) was administered i.v. to all fetal sheep at 130-134 days gestation. There was a significant fetal PRL response to TRH in both the HPD (F = 20.9, P < 0.001) and sham (F = 31.3, P < 0.001) groups. There was no difference, however, in the PRL response to TRH in fetal sheep previously exposed to SL or LL in either the HPD or sham groups. The maximum percentage changes in PRL occurred at +10 min after TRH administration in the HPD (pre-SL, 421 +/- 75%; pre-LL, 555 +/- 76%) and sham groups (pre-SL, 394 +/- 68%; pre-LL, 369 +/- 59%). In summary, therefore, we have demonstrated that there is an effect of photoperiodic history on the PRL response to an intermediate photoperiod in utero in HPD fetal sheep. It appears, however, that the effect of photoperiodic history on PRL secretion in intact fetal sheep is either masked or suppressed by the stimulatory effect of factors associated with an increase in gestational age acting at the fetal hypothalamus.

Melatonin and the light-dark cycle separately influence daily behavioral and hormonal rhythms in the pregnant ewe and sheep fetus.

We have studied the effects of independently altering the time of darkness and the phase of the daily melatonin rhythm during a 12-h photoperiod on the diurnal rhythms of fetal breathing movements (FBMs), low voltage electrocortical activity, and maternal and fetal plasma concentrations of PRL. Thirteen pregnant ewes were pinealectomized at 99-100 days gestation and held under a normal lighting regime (12-h photoperiod, lights off at 1900 h) until 135 days gestation. All ewes were then exposed to an altered lighting regime (12-h photoperiod, lights off at 1100 h) until 145 days gestation. Six of these ewes were infused with melatonin (12-15 micrograms/h iv) from 1100 h for 12 h each day between 125 and 135 days gestation while in the normal lighting regime, and from 1900 h while in the altered lighting regime. The remaining seven ewes were infused with saline at corresponding times. Infusion of melatonin produced a significant daily rhythm in maternal and fetal melatonin concentrations; concentrations were highest throughout the 12-h infusion period in each lighting regime. In the normal lighting regime (i.e. lights off at 1900 h) the peak incidence of FBM occurred at between 1000 and 1300 h in the ewes infused with saline or melatonin. Under the altered lighting conditions there was no 24-h variation in the incidence of FBMs in the saline-infused group, but a significant daily variation was present in the melatonin-infused group with peak incidence occurring at 1900-2200 h. The daily variation in maternal PRL concentrations was not affected by changes in the time of onset of melatonin infusion but was different in each of the two lighting regimes. In the normal lighting regime, PRL concentrations were highest at 2100 h (56.2 +/- 21.6 ng/ml) whereas in the altered lighting conditions the peak in maternal PRL occurred at 1700 h (90.4 +/- 25.1 ng/ml). The daily variation in fetal PRL concentrations was also not affected by changes in the time of onset of melatonin infusion but was different in the two lighting regimes; in the normal lighting regime, fetal PRL reached a peak (13.0 +/- 3.7 ng/ml) at 0100-0300 h whereas in the altered lighting regime the peak (29.2 +/- 9.8 ng/ml) occurred at 1700-2100 h. We have presented evidence therefore that the daily melatonin rhythm may entrain the daily rhythm in fetal breathing activity.(ABSTRACT TRUNCATED AT 400 WORDS)

The regulation of prolactin receptor messenger ribonucleic acid levels in the sheep liver before birth: relative roles of the fetal hypothalamus, cortisol, and the external photoperiod.

We have investigated the separate actions of hypothalamo-pituitary disconnection (HPD), with or without cortisol administration, and changes in the external photoperiod on the regulation of the levels of messenger RNA (mRNA) encoding long (PRLR1) and short (PRLR2) forms of PRL receptor in the liver of the fetal lamb. In pregnant Merino ewes (n = 20), the hypothalamus and pituitary were surgically disconnected in 13 fetuses (HPD group), and fetal vascular catheters were implanted in the HPD group and in an additional 7 fetuses (intact + saline group) between 104-120 days gestation (d). Fetal sheep in the HPD group were infused with either cortisol (3.5 mg/4.8 ml saline/24 h; HPD + F; n = 5) or saline for 5 days between 134-141 d, and saline was also infused in the intact group within the same gestational age range. A second group of pregnant ewes (n = 12) was kept in a 12-h light, 12-h dark cycle from 70 d until implantation of fetal vascular catheters between 106-120 d, after which ewes were allocated to either a long photoperiod (16 h of light, 8 h of darkness; LL group; n = 6) or a short photoperiod (8 h of light, 16 h of darkness; SL group; n = 6) regimen. Circulating cortisol concentrations were higher (P < 0.05) in the intact fetal sheep (18.7 +/- 3.8 nmol/liter) than in the HPD + saline group (1.5 +/- 0.6 nmol/liter), and were further increased (P < 0.05) in the HPD + cortisol group (97.4 +/- 23.7 nmol/liter). Fetal PRL concentrations were lower (P < 0.05) in the HPD + saline (10.6 +/- 4.3 ng/ml) and HPD + cortisol (5.6 +/- 2 ng/ml) groups compared with those in the intact group (38.9 +/- 6.8 ng/ml). The levels of hepatic PRLR mRNA were higher (P < 0.05) in the intact (PRLR1, 27.4 +/- 6.1; PRLR2, 17.7 +/- 2.5) and HPD + cortisol (PRLR1, 23.4 +/- 0.4; PRLR2, 15.3 +/- 3.0) groups than in the HPD + saline group (PRLR1, 10.6 +/- 1.8; PRLR2, 8.9 +/- 1.8) at 140/141 d. The mean plasma PRL concentration in the LL group (70 +/- 9 ng/ml) was higher (P < 0.05) than that in the SL group (34 +/- 15 ng/ml), whereas the levels of hepatic PRLR1 mRNA (LL group, 4.6 +/- 0.9; SL group, 4.3 +/- 0.8) and PRLR2 mRNA (LL group, 3.4 +/- 0.4; SL group, 3.0 +/- 0.5) at 140-141 d were not different. These data indicate that cortisol acts directly or indirectly to maintain hepatic PRLR mRNA levels in the sheep fetus during late pregnancy. In contrast, changes in the external photoperiod and circulating PRL concentrations in the sheep fetus do not directly alter PRLR expression in the fetal liver. These studies provide further insight into the role that the PRL axis may play in the transduction of signals about the external environment to the fetus as it prepares for the transition to extrauterine life.

Modification of experimental nephrotoxicity with fish oil as the vehicle for cyclosporine.

Cyclosporine-associated renal dysfunction is well recognized. While renal vasoconstriction appears to be a major pathogenic factor, the precise mechanism responsible for the altered hemodynamics is unclear. To investigate whether alterations in renal eicosanoid metabolism could be involved, we substituted fish oil rich in eicosapentaenoic acid (EPA), an inhibitor of cyclooxygenase metabolites, for the conventional olive oil cyclosporine vehicle. Male rats were pretreated with 1.0 cc fish oil or olive oil by gavage. After 14 days, cyclosporine (12.5 mg/cc vehicle) was added to the oil and animals received cyclosporine 50 mg/kg for an additional 14 days. Pair-fed control animals received fish oil or olive oil alone. Glomerular filtration rate (GFR) was severely reduced in the cyclosporine-in-olive-oil (CSA + OO) group (0.28 +/- .05 ml/min/100 g) vs. olive oil (OO) controls (0.70 +/- .04) (P less than 0.001). While GFR was reduced in the cyclosporine-in-fish oil group (CSA + FO) vs. fish oil (FO) controls (0.47 +/- .07 vs. 0.74 +/- .04), it was significantly higher than in the CSA + OO group (P less than 0.05). Trough whole-blood cyclosporine levels were not significantly different in the two groups. While CSA + OO appeared to elevate renal cortical content of thromboxane B2 (65.7 +/- 7.3 pg/mg tissue vs. 46.9 +/- 5.3 for OO), both the CSA + FO and FO groups had reduced levels (31.1 +/- 2.7 and 29.5 +/- 2.3, respectively). In addition, there was a striking reduction in proximal tubular vacuolar changes in the CSA +/- FO vs. CSA + OO group. We conclude that the use of EPA-rich fish oil as the vehicle for cyclosporine results in improved renal function and morphology and is associated with depressed renal cortical levels of vasoconstrictor thromboxane B2.

Cyclosporine-induced acute renal dysfunction in the rat. Evidence of arteriolar vasoconstriction with preservation of tubular function.

Dose-related cyclosporine-induced renal dysfunction is the most frequent adverse effect noted with this exciting immunosuppressive drug. To investigate pathogenetic factors involved, we studied renal tubular function and afferent arteriolar morphology during severe experimental cyclosporine-induced reduction in glomerular filtration rate. Pair-fed male rats were given cyclosporine 50 mg/kg or olive oil vehicle alone by gavage for periods of 3-14 days. Glomerular filtration rate declined progressively, reaching a nadir of 0.18 +/- .05 ml/min/100 g vs. .86 +/- .03 ml/min/100 g in controls at 14 days (P less than 0.001). Despite the severe reduction in glomerular filtration rate there was no difference in fractional sodium excretion, fractional lithium excretion, enzymuria, or in vitro renal cortical slice uptake of tetraethylammonium in cyclosporine and vehicle-treated animals. Light microscopy showed vacuolar changes without evidence of tubular necrosis at 7 and 14 days in cyclosporine-treated rats. Progressive decline in the diameter of the afferent arteriole was noted by scanning electron microscopy. By day 14 the lumenal diameter of afferent arterioles from cyclosporine-treated animals was 8.9 +/- 0.4 micron vs. 13.5 +/- 0.4 micron in controls (P less than 0.05). We conclude that afferent arteriolar vasoconstriction rather than direct tubular injury is a major pathogenetic factor in experimental cyclosporine nephrotoxicity.

Clinically relevant doses and blood levels produce experimental cyclosporine nephrotoxicity when combined with nitric oxide inhibition.

Cyclosporine (CsA) administration and nitric oxide (NO) blockade promote similar chronic renal hemodynamic alterations in rats. We evaluated various clinical CsA doses under conditions of NO blockade using L-NAME (N-nitro L-arginine methyl ester). Groups of Sprague-Dawley rats kept on a normal salt (+NaCl) or low-salt (-NaCl) diet were given CsA 7.5 mg/kg, 2.5 mg/kg, or vehicle (VH) for 21 days. CsA or VH treatment was preceded by one week of L-NAME and continued for three weeks. Inulin clearance, CsA blood level, and weekly blood pressure change were assessed at 28 days. Marked CsA dose dependent reductions in GFR in -NaCl animals (P < 0.01 versus VH + L-NAME) and +NaCl animals (P < 0.05 versus VH + L-NAME, +NaCl) as well as blood pressure elevations (P < 0.01 versus VH + L-NAME at 28 days) occurred in groups concurrently treated with CsA and L-NAME. In addition, Impaired renal function and morphologic lesions in rats (CsA 2.5 mg/kg) receiving L-NAME or CsA alone demonstrated CsA blood levels within the therapeutic range of human renal transplant patients. VH groups treated with L-NAME alone produced blood pressure elevations but were spared of renal functional or morphological alterations. Primary renal morphologic lesions in CsA treated animals included proximal tubule collapse and vacuolization and, less frequently, interstitial edema and vacuolization of interstitial cells. Unique to rats treated simultaneously with CsA and L-NAME were vascular abnormalities consisting of endothelial and arteriolar medial hyperplasia and occasional acute medial necrosis. In conclusion, acute CsA nephrotoxicity can be enhanced by simultaneous NO blockade, suggesting NO has a protective effect in CsA-induced nephropathy. These results can be achieved with a drug exposure profile that correlates with clinical therapy.

Enhancement of FK506 nephrotoxicity by sodium depletion in an experimental rat model.

FK506 can show efficacy in transplant rejection even after other immunosuppressive drugs have been ineffective. However, the lack of a suitable animal model has hindered the study of FK nephrotoxicity, which has been noted as a common adverse effect in human trials. In this paper, we report a model of chronic FK nephrotoxicity in which renal structure and function are worsened by sodium depletion. Pair-fed male Sprague-Dawley rats were given FK (6 mg/kg p.o.) or vehicle for 21 days on a low-salt or normal diet. There was no significant difference in body weight between FK and vehicle groups. The FK whole-blood trough levels (3-10 ng/ml) in rats are similar to those in FK treated transplant patients. In sodium-depleted rats, FK clearly decreased GFR (0.09 +/- 0.03 ml/min/100 g vs. 0.94 +/- 0.06 ml/min/100 g in the vehicle group, P < 0.01), urinary osmolarity (UOsm, P < 0.01) and plasma magnesium (P < 0.01) and increased plasma creatinine (Pcr, P < 0.01), fractional excretion of magnesium (P < 0.01), urine volume (P < 0.01), plasma renin activity (PRA, P < 0.05), and alanine aminopeptidase (AAP, P < 0.05) as compared with those in the vehicle group. Salt depletion significantly potentiated these functional changes as compared with those in the normal salt group (GFR, UOsm, Pcr, PRA, and AAP of the low salt group vs. those of the normal salt group, P < 0.05 by ANOVA). In the sodium-depleted rats, the main lesion in the rat kidneys was focal collapse and vacuolization in proximal tubules, but there was also significant interstitial fibrosis. In contrast, no injury was observed in the sodium-replete rat kidneys. In conclusion, an experimental model of FK nephrotoxicity in sodium-depleted rats has been developed that is characterized by reduced GFR and structural damage to the proximal tubule accompanied by interstitial fibrosis. Sodium depletion appears to potentiate these changes at blood levels similar to those achieved in patients receiving FK.

Membranous nephropathy associated with chronic immune thrombocytopenic purpura in childhood.

Membranous nephropathy has been associated with many autoimmune diseases. We describe a child with membranous nephropathy associated with chronic immune thrombocytopenic purpura (ITP) and Coombs'-positive hemolytic anemia. After 3 years of ITP, the patient developed nephrotic syndrome during a flare of ITP. A biopsy specimen showed membranous nephropathy. Treatment with corticosteroids led to improvement of the thrombocytopenia and resolution of the proteinuria. Two years later, the patient again developed thrombocytopenia and proteinuria. Both conditions resolved after treatment with corticosteroids. This case suggests that ITP can cause membranous nephropathy.

Renal mitochondrial integrity during continuous gentamicin treatment.

Rats were given gentamicin over a period of 21 days. At 5, 10, 14 and 21 days renal cortical mitochondria were isolated, and respiratory and Ca2+ transport functions and cytochrome concentrations were determined. The mitochondrial data were correlated with indicators of deteriorating renal function and tissue gentamicin accumulation. During the first 10 days of chronic gentamicin treatment, mitochondrial cytochrome oxidase and cytochrome c concentrations declined significantly. This decline was followed by a partial spontaneous recovery by days 14 and 21. Cytochrome b concentration was not significantly different from normal. Parallel with the cytochrome concentration changes, State 3 respiratory activities with all substrates studied and the rates of Ca2+ accumulation declined during the first 10 days and recovered spontaneously thereafter. It is concluded that chronic gentamicin treatment leading to renal failure inhibits mitochondrial energy-linked functions, which inhibition is induced by rate-limiting synthesis of those mitochondrial respiratory chain enzymes coded outside the mitochondrion.

Renal oncocytoma.

Renal oncocytoma is a rare tumor of probable proximal tubular origin characterized by uniform cells with abundant, granular, brightly eosinophilic cytoplasm containing numerous mitochondria. The tumor is benign clinically and can be distinguished from renal cell carcinoma.

Bis (2,3-dibromopropyl) phosphate nephrotoxicity: effect of sex and CoCl2 pretreatment.

Bis (2,3-dibromopropyl) phosphate (BIS-BP) is one of two identified metabolites of Tris (2,3-dibromopropyl) phosphate (TRIS-BP). We have previously shown that BIS-BP is more acutely nephrotoxic than TRIS-BP. We now report the effect of sex and inhibition of drug metabolism on BIS-BP toxicity. Compared to male rats, age-matched female rats developed less severe and extensive structural damage after BIS-BP. Renal dysfunction, as indexed by serum creatinine and in vitro renal cortical uptake of para-aminohippurate and N-(14C) methylnicotinamide was similar in males and females. Pretreatment of males with the drug metabolism inhibitor, cobaltous chloride, reduced both functional and structural evidence of BIS-BP toxicity. In separate studies, there was no difference in the distribution of radiolabel in male and female rats three days after administration of 14C-TRIS-BP. These studies showing that female rats are resistant to acute BIS-BP structural damage may explain the previously reported lack of carcinogenicity of TRIS-BP in female rats. The reduction of BIS-BP toxicity by CoCl2 suggests that unidentified, nephrotoxic metabolites exist and are responsible for part of the nephrotoxicity of BIS-BP.

Effect of phenobarbital and cimetidine on experimental cyclosporine nephrotoxicity: preliminary observations.

Cyclosporine is metabolized by the hepatic microsomal cytochrome P-450 mixed function oxidases. To determine the effects of inducers and inhibitors of this enzyme on nephrotoxicity, male Fischer 344 rats were treated with cyclosporine in doses of 25 mg/kg and 40 mg/kg by daily gavage for 14 days. Groups of animals were given phenobarbital 75 mg/kg i.p., cimetidine 75 mg/kg i.p., or .9% saline i.p. for 3 days prior to starting cyclosporine and throughout therapy. Animals treated with the oil vehicle for cyclosporine served as controls. Animals receiving cyclosporine together with phenobarbital hat better preservation of glomerular filtration rate than did other cyclosporine-treated animals. Cimetidine did not enhance cyclosporine nephrotoxicity. Direct tubular toxicity was not evident using cortical slice transport of tetraethylammonium, fractional excretion of sodium and light microscopy as markers. If phenobarbital protects from cyclosporine nephrotoxicity because of its enzyme inducing action, it would follow that the parent drug and not a toxic metabolite mediates renal dysfunction. Based on the decreased glomerular filtration rate in the absence of overt tubular damage the major mechanism of cyclosporine nephrotoxicity is probably related to vascular or glomerular effects of the drug.

Myeloid bodies in the renal tubules of humans: relationship to gentamicin therapy.

Ultrastructural changes in renal proximal tubule lysosomes, including the formation of myeloid bodies, occur reliably with gentamicin administration in experimental animals. The present study reviewed the electron microscopic tubular morphology of renal biopsies and nephrectomies performed in our institution over a 2-year period. The frequency of myeloid bodies and their relation to drug therapy and selected clinical features were determined. Myeloid bodies were found in the proximal tubules of 19 of 109 cases that were judged adequate for study. On review of the drug histories of these 19 patients, 15 had received gentamicin within 6 weeks of biopsy or nephrectomy. None of the 90 patients without myeloid bodies had received the drug within 6 weeks of tissue examination. Of 4 patients with myeloid bodies who had not received gentamicin, 1 had received chloroquin and 3 had received drugs with no known or suspected capacity to induce myeloid bodies. The presence of myeloid bodies in proximal tubules did not appear to be related to the total dose of gentamicin, duration of therapy, or serum drug concentration. Clinical evidence of gentamicin nephrotoxicity was present in only 1 case.

Concurrent spindle cell peripheral pulmonary carcinoid tumor and Merkel cell tumor of the skin.

To our knowledge this is the first reported case of concurrent Merkel cell (trabecular carcinoma) tumor and peripheral pulmonary carcinoid tumor. Both tumors are considered to neuroendocrine in nature. The significance of concurrent neuroendocrine tumors is described with respect to multiple endocrine neoplasia syndrome variants and possible pathophysiology.