Medullary nephrocalcinosis associated with long-term furosemide abuse in adults

BACKGROUND

The use of furosemide is well recognized as a predisposing factor of nephrocalcinosis in infants. Although furosemide is widely used for various medical conditions in adults, its association with nephrocalcinosis in adults is not well established.

METHODS

We studied 18 consecutive adult patients (male:female ratio 1:17, age range 21-59 years) who habitually took furosemide to control weight or oedema for long periods of time (range 3-25 years). The daily dose of continuous intake of furosemide ranged from 40 to 2800 mg. Nephrocalcinosis was evaluated using renal ultrasonography (US), computed tomography (CT), or kidney biopsies.

RESULTS

Renal US and CT revealed bilateral nephrocalcinosis of the medullary pyramids in 15 (83.3%) out of 18 patients. The duration of furosemide abuse was similar between nephrocalcinosis positive (NC(+)) and nephrocalcinosis negative (NC(-)) groups. The daily dose of furosemide was nearly 10 times higher in the NC(+) group (range 120-2800 mg, mean 538 mg) than the NC(-) group (range 40-80 mg, mean 67 mg). All patients showed variable degrees of renal insufficiency and there was no difference in creatinine clearance between the NC(+) and NC(-) groups (P>0.05). Kidney biopsies performed in three patients showed focal tubulo-interstitial fibrosis and atrophy and calcifications were observed in outer medullary tubulo-interstitium.

CONCLUSIONS

Long-term furosemide abuse can cause medullary nephrocalcinosis in adults, and the risk of developing of nephrocalcinosis seems to be correlated with the daily dose of furosemide. We suggest that long-term furosemide abuse should be suspected in adult patients when medullary nephrocalcinosis is incidentally detected by US or CT.

Elevated uric acid increases blood pressure in the rat by a novel crystal-independent mechanism

An elevation in circulating serum uric acid is strongly associated with the development of hypertension and renal disease, but whether uric acid has a causal role or whether it simply indicates patients at risk for these complications remains controversial. We tested the hypothesis that uric acid may have a causal role in the development of hypertension and renal disease by examining the effects of mild hyperuricemia in rats. Mild hyperuricemia was induced in rats by providing a uricase inhibitor (oxonic acid) in the diet. Hyperuricemic rats developed elevated blood pressure after 3 weeks, whereas control rats remained normotensive. The development of hypertension was prevented by concurrent treatment with either a xanthine oxidase inhibitor (allopurinol) or a uricosuric agent (benziodarone), both of which lowered uric acid levels. Blood pressure could also be lowered by reducing uric acid levels with either allopurinol or oxonic acid withdrawal. A direct relationship was found between blood pressure and uric acid (r=0.75, n=69), with a 10-mm Hg blood pressure increase for each 0.03-mmol/L (0.5-mg/dL) incremental rise in serum uric acid. The kidneys were devoid of urate crystals and were normal by light microscopy. However, immunohistochemical stains documented an ischemic type of injury with collagen deposition, macrophage infiltration, and an increase in tubular expression of osteopontin. Hyperuricemic rats also exhibited an increase in juxtaglomerular renin and a decrease in macula densa neuronal NO synthase. Both the renal injury and hypertension were reduced by treatment with enalapril or L-arginine. In conclusion, mild hyperuricemia causes hypertension and renal injury in the rat via a crystal-independent mechanism, with stimulation of the renin-angiotensin system and inhibition of neuronal NO synthase.

Effects of cysteine on the pharmacokinetics of intravenous phenytoin in rats with protein-calorie malnutrition

The effects of cysteine on the pharmacokinetics of phenytoin and one of its metabolites, 5-(p-hydroxyphenyl)-5-phenylhydantoin (pHPPH) were investigated after intravenous administration of phenytoin, 25 mg/kg, to control rats (4-week fed on 23% casein diet) and rats with PCM (protein-calorie malnutrition, 4-week fed on 5% casein diet) and PCMC (PCM with oral cysteine supplementation, 250 mg/kg, twice daily starting from the fourth week). In rats with PCM and PCMC, the phenytoin hydroxylation (to form pHPPH) activities were significantly smaller (164, 103 and 95.3 pmol/min per mg protein for the control rats, and rats with PCM and PCMC, respectively) than that in control rats. In rats with PCMC, the intrinsic clearance of phenytoin, CL(int) was significantly slower than those in control rats and rats with PCM (0.175, 0.131 and 0.044 ml/min). The above data suggested that the formation of pHPPH could be reduced in rats with PCM and PCMC. This was supported by significantly smaller 24-h urinary excretion of pHPPH (54.7, 35.6 and 32.5% of intravenous dose of phenytoin) in rats with PCM and PCMC than that in control rats. In rats with PCM, the maximum velocity (0.344, 0.203 and 0.196 microg/min), apparent volume of distribution in central compartment (44.4, 65.4 and 72.2 ml/kg) of phenytoin, and total area under the plasma concentration-time curve from time zero to time infinity (609, 714 and 1210 microg min/ml), renal clearance (20.5, 13.4 and 4.67 ml/min per kg) and 24-h urinary excretion (54.7, 35.6 and 32.5% of intravenous dose of phenytoin) of pHPPH were not returned to control levels by cysteine supplementation (rats with PCMC). This could be mainly due to the fact that the phenytoin hydroxylation activity in rats with PCMC was not returned to control level.

Hypokalemia induces renal injury and alterations in vasoactive mediators that favor salt sensitivity

We investigated the hypothesis that hypokalemia might induce renal injury via a mechanism that involves subtle renal injury and alterations in local vasoactive mediators that would favor sodium retention. To test this hypothesis, we conducted studies in rats with diet-induced K+ deficiency. We also determined whether rats with hypokalemic nephropathy show salt sensitivity. Twelve weeks of hypokalemia resulted in a decrease in creatinine clearance, tubulointerstitial injury with macrophage infiltration, interstitial collagen type III deposition, and an increase in osteopontin expression (a tubular marker of injury). The renal injury was greatest in the outer medulla with radiation into the cortex, suggestive of an ischemic etiology. Consistent with this hypothesis, we found an increased uptake of a hypoxia marker, pimonidazole, in the cortex. The intrarenal injury was associated with increased cortical angiontensin-converting enzyme (ACE) expression and continued cortical angiotensin II generation despite systemic suppression of the renin-angiotensin system, an increase in renal endothelin-1, a decrease in renal kallikrein, and a decrease in urinary nitrite/nitrates and prostaglandin E(2) excretion. At 12 wk, hypokalemic rats were placed on a normal-K+ diet with either high (4%)- or low (0.01%)-NaCl content. Despite correction of hypokalemia and normalization of renal function, previously hypokalemic rats showed an elevated blood pressure in response to a high-salt diet compared with normokalemic controls. Hypokalemia is associated with alterations in vasoactive mediators that favor intrarenal vasoconstriction and an ischemic pattern of renal injury. These alterations may predispose the animals to salt-sensitive hypertension that manifests despite normalization of the serum K+.

Vascular endothelial growth factor (VEGF121) protects rats from renal infarction in thrombotic microangiopathy

BACKGROUND

Renal thrombotic microangiopathy, typified by the hemolytic uremic syndrome, is associated with endothelial cell injury in which the presence of cortical necrosis, extensive glomerular involvement, and arterial occlusive lesions correlates with a poor clinical outcome. We hypothesized that the endothelial survival factor vascular endothelial growth factor (VEGF) may provide protection.

METHOD

Severe, necrotizing, thrombotic microangiopathy was induced in rats by the renal artery perfusion of antiglomerular endothelial antibody, followed by the administration of VEGF or vehicle, and renal injury was evaluated.

RESULTS

Control rats developed severe glomerular and tubulointerstitial injury with extensive renal necrosis. The administration of VEGF significantly reduced the necrosis, preserved the glomerular endothelium and arterioles, and reduced the number of apoptotic cells in glomeruli (at 4 hours) and in the tubulointerstitium (at 4 days). The prosurvival effect of VEGF for endothelium may relate in part to the ability of VEGF to protect endothelial cells from factor-induced apoptosis, as demonstrated for tumor necrosis factor-alpha (TNF-alpha), which was shown to be up-regulated through the course of this model of renal microangiopathy. Endothelial nitric oxide synthase expression was preserved in VEGF-treated rats compared with its marked decrease in the surviving glomeruli and interstitium of the antibody-treated rats that did not receive VEGF.

CONCLUSIONS

VEGF protects against renal necrosis in this model of thrombotic microangiopathy. This protection may be mediated by maintaining endothelial nitric oxide production and/or preventing endothelial cell death.

Dissociation between clearances of small and middle molecules in incremental peritoneal dialysis

OBJECTIVE

To evaluate the peritoneal clearance of middle molecules in comparison with the peritoneal clearance of small molecules in incremental peritoneal dialysis (PD).

STUDY DESIGN

Peritoneal clearances of creatinine and beta2-microgloblulin (B2M) were compared in 57 continuous ambulatory PD patients on full dose of 4 exchanges, and 54 incremental PD patients with 2 or 3 exchanges over 24 hours. Clearances were also compared when there were changes in the PD regimen, such as in the number of exchanges and the duration of the dwell time.

SETTING

Tertiary-care university hospital.

RESULTS

Peritoneal creatinine clearance increased almost linearly with the increase in the number of exchanges. In contrast, peritoneal clearance of B2M was 9.1 +/- 3.6 L/week, 8.8 +/- 4.4 L/week, and 7.9 +/- 2.5 L/week with 2,3, and 4 exchanges, respectively, per day, amounts that were not different from each other. Peritoneal clearance of B2M did not change when there was an increase in the number of dialysate exchanges from 2 to 3 and from 3 to 4 over a period of 24 hours; whereas the peritoneal clearance of creatinine increased. Peritoneal clearance of B2M almost doubled, from 5.4 +/- 2.7 L/week with 2 exchanges over 12 hours per day, to 9.5 +/- 4.4 L/week with the same 2 exchanges over 24 hours. The creatinine clearance did not change.

CONCLUSION

In contrast to peritoneal clearance of small molecules, such as creatinine, which was dependent on the number of dialysate exchanges, peritoneal clearance of middle molecules, such as B2M, depended mainly on the total dwell hours of PD and not on the number of exchanges of peritoneal dialysate in incremental PD. This might be another advantage of incremental PD, since peritoneal clearance of middle molecules in incremental PD over 24 hours can be comparable to that in full dose PD.

Intravenous immunoglobulin protects against experimental thrombotic microangiopathy

BACKGROUND

Intravenous immunoglobulin (IVIG) has been utilized in several forms of vasculitis and has many potential mechanisms of action, including the inhibition of C3 activation. We have previously demonstrated that IVIG can reduce glomerular injury in a model of membranous nephropathy mediated by C5b-9 [1]. C5b-9 has also been shown to mediate the thrombotic microangiopathy (TMA) induced by antibody to glomerular endothelial cells leading to a hemolytic uremic syndrome-type lesion [2].

METHODS

To test the hypothesis that IVIG might be effective in treating antibody-induced TMA, male uninephrectomized rats underwent right renal artery perfusion with goat anti-rat glomerular endothelial cell (GEN) antibody (20 mg/kg). Sheep IgG (200 mg/kg) was administered either 30 minutes before the renal artery perfusion (group I, N = 6) or 30 minutes postperfusion (group II, N = 9). A third control group received phosphate-buffered saline (PBS; group III, N = 12). A survival biopsy was performed at 15 minutes, and the animals were sacrificed on day 2.

RESULTS

There were no significant differences in proteinuria or hematocrit between the groups. Animals pretreated with IVIG had significantly improved survival and renal function, which was associated with a decrease in glomerular C3 deposition. The protective effect of IVIG was abolished if the administration was delayed 30 minutes after perfusion.

CONCLUSIONS

IVIG is effective in reducing injury in experimental TMA only if given prophylactically. The effect is mediated by inhibition of local intraglomerular complement activation.

Bioequivalence of clarithromycin tablet formulations assessed in Korean males

AIM

Determination of the bioequivalence of 2 clarithromycin tablet formulations manufactured in Korea.

PATIENTS AND METHODS

Twenty-four healthy male Korean volunteers received each of the 2 clarithromycin formulations at a dose of 250 mg in a 2 x 2 crossover study. There was a one-week washout period between doses. Plasma concentrations of clarithromycin were monitored by high-performance liquid chromatography over a period of 12 hours after administration. AUCinf (the area under the plasma concentration-time curve from time zero to time infinity) was calculated using the linear-log trapezoidal method. Cmax (maximum plasma drug concentration) and Tmax (time to reach Cmax) were compiled from the plasma concentration-time data. Analysis of variance was carried out using logarithmically transformed AUCinf and Cmax and untransformed Tmax.

RESULTS

The point estimates and 90% confidence intervals for AUCinf (parametric) and Cmax (parametric) were 0.971 (0.886 approximately 1.063) and 0.982 (0.868 approximately 1.107), respectively, satisfying the bioequivalence criteria of the European Committee for Proprietary Medicinal Products and the US Food and Drug Administration guidelines. The corresponding value of Tmax was 0.000 (-0.250 approximately 0.250).

CONCLUSION

These results indicate that the 2 medications of clarithromycin are bioequivalent and, thus, may be prescribed interchangeably.

Measurement of the midrapidity transverse energy distribution from square root of [(s)NN] = 130 GeV Au + Au collisions at RHIC

The first measurement of energy produced transverse to the beam direction at the Relativistic Heavy-Ion Collider at Brookhaven National Laboratory is presented. The midrapidity transverse energy density per participating nucleon rises steadily with the number of participants, closely paralleling the rise in charged-particle density, such that <E(T)>/<N(ch)> remains relatively constant as a function of centrality. The energy density calculated via Bjorken's prescription for the 2% most central Au+Au collisions at square root[s(NN)] = 130 GeV is at least epsilon(Bj) = 4.6 GeV/fm(3), which is a factor of 1.6 larger than found at sqrt[s(NN)] = 17.2 GeV ( Pb+Pb at CERN).

Hyperuricemia exacerbates chronic cyclosporine nephropathy

BACKGROUND

Hyperuricemia frequently complicates cyclosporine (CSA) therapy. The observation that longstanding hyperuricemia is associated with chronic tubulointerstitial disease and intrarenal vasoconstriction raised the hypothesis that hyperuricemia might contribute to chronic CSA nephropathy.

METHODS

CSA nephropathy was induced by the administration of CSA (15 mg/kg/day) for 5 and 7 weeks to rats on a low salt diet (CSA group). The effect of hyperuricemia on CSA nephropathy was determined by blocking the hepatic enzyme uricase with oxonic acid (CSA-OA). Control groups included rats treated with vehicle (VEH) and oxonic acid alone (OA). Histological and functional studies were determined at sacrifice.

RESULTS

CSA treated rats developed mild hyperuricemia with arteriolar hyalinosis, tubular injury and striped interstitial fibrosis. CSA-OA treated rats had higher uric acid levels in association with more severe arteriolar hyalinosis and tubulointerstitial damage. Intrarenal urate crystal deposition was absent in all groups. Both CSA and CSA-OA treated rats had increased renin and decreased NOS1 and NOS3 in their kidneys, and these changes are more evident in CSA-OA treated rats.

CONCLUSION

An increase in uric acid exacerbates CSA nephropathy in the rat. The mechanism does not involve intrarenal uric acid crystal deposition and appears to involve activation of the renin angiotensin system and inhibition of intrarenal nitric oxide production.

Effects of yukmi, an herbal formula, on the liver of senescence accelerated mice (SAM) exposed to oxidative stress

The effects of yukmi (Decoction of six plants including rehmannia), an herbal formula, were studied on liver oxidant damage induced by paraquat (PQ) administered intravenously in the senescence accelerated mice (SAM-P/8). The activities of superoxide dismutase (SOD) and catalase as two major antioxidant enzymes and lipid peroxidation levels were determined for six days. Data show that the activities of hepatic SODs and catalase were increased by oral administration of yukmi extracts following PQ pretreatment. Herbal medicine effectively blocked the PQ-induced effects on liver malondialdehyde (MDA) levels. For the histopathological changes in SAM-P/8 liver, yukmi extracts inhibited PQ-induced damage to the hepatic mitochondria and their membranes. Data suggest that yukmi extracts may be useful in protecting against oxidative damage.

Genomic clustering of tRNA-specific adenosine deaminase ADAT1 and two tRNA synthetases

Human tRNA-specific adenosine deaminase (hADAT1) specifically converts A37 in the anticodon loop of human tRNA(Ala) to inosine via a hydrolytic deamination mechanism. The enzyme is related to a family of RNA editing enzymes (ADARs) specific for pre-mRNA, and it has been cloned based on its sequence homology to the catalytic domain of ADARs. In the present study we have analyzed the 5'-flanking sequence of the murine ADAT1 gene, revealing that the first transcribed exon is located 1.1 kb downstream from the polyadenylation site of lysyl tRNA synthetase (KARS). The close proximity is conserved in the human genome with an intergenic distance of 5.5 kb. We determined the complete cDNA sequence as well as exon/intron organization of murine KARS. Significant sequence similarities between KARS and ADAT1 are apparent within their substrate interaction domains. Radiation hybrid panel analysis mapped human ADAT1 and human KARS to region q22.2--22.3 of Chromosome (Chr) 16 with alanyl tRNA synthetase (AARS) positioned centromeric to the KARS and ADAT1 genes. 16q22--24 has recently been recognized as a susceptibility candidate locus for several autoimmune inflammatory diseases. The clustering of three tRNA specific genes, of which two are specific for tRNA(Ala), may indicate their evolutionary relatedness or common factors involved in regulating their expression.

Centrality dependence of charged particle multiplicity in Au-Au collisions at square root of (s)NN = 130 GeV

We present results for the charged-particle multiplicity distribution at midrapidity in Au-Au collisions at square root of [s(NN)] = 130 GeV measured with the PHENIX detector at RHIC. For the 5% most central collisions we find dN(ch)/d eta(vertical line eta = 0) = 622+/-1(stat)+/-41(syst). The results, analyzed as a function of centrality, show a steady rise of the particle density per participating nucleon with centrality.

Post-cyclosporine-mediated hypertension and nephropathy: amelioration by vascular endothelial growth factor

Recent studies have demonstrated a role for microvascular and tubulointerstitial injury in some models of salt-sensitive hypertension. We utilized a model of post-cyclosporin A (CsA) nephropathy and hypertension to test the hypothesis that treatment with an angiogenic factor aimed at ameliorating the microvascular and renal injury would prevent the development of hypertension. CsA was administered with a low-salt diet for 45 days, resulting in a renal lesion characterized by afferent arteriolopathy, focal peritubular capillary loss, and tubulointerstitial fibrosis. Rats were then placed on a high-salt diet and randomized to receive either vascular endothelial growth factor (VEGF(121)) or vehicle for 14 days. Placement of rats with established CsA nephropathy on a high-salt diet results in the rapid development of salt-sensitive hypertension. VEGF(121) treatment resulted in lower blood pressure, and this persisted on discontinuing the VEGF. VEGF(121) treatment was also associated with a decrease in osteopontin expression, macrophage infiltration, and collagen III deposition and markedly stimulated resolution of the arteriolopathy (20.9 +/- 7.8 vs. 36.9 +/- 6.1%, VEGF vs. vehicle, P < 0.05). In conclusion, CsA-associated renal microvascular and tubulointerstitial injury results in the development of salt-sensitive hypertension. Treatment of animals with established CsA nephropathy with VEGF reduces the hypertensive response and accelerates histological recovery. The vascular protective effect of VEGF may be due to the improvement of arteriolopathy. Angiogenic growth factors may represent a novel strategy for treating CsA-associated hypertension and renal disease.

Effects of cysteine on the pharmacokinetics and pharmacodynamics of intravenous and oral azosemide in rats with protein-calorie malnutrition

The effects of cysteine on the pharmacokinetics and pharmacodynamics of azosemide were investigated after intravenous (10 mg/kg) and oral (20 mg/kg) administration to male Sprague-Dawley rats fed on 23% protein diet (control rats), and 5% protein diet with (rats with PCMC) or without (rats with PCM) oral cysteine (250 mg/kg, twice daily for the fourth week) for 4 weeks. After intravenous administration to rats with PCMC, some pharmacokinetic parameters restored fully or more than the level of control rats; the time-averaged nonrenal clearance (2.70 versus 2.32 ml/min/kg) and apparent volume of distribution at steady state (160 versus 189 ml/kg) were comparable to those in control rats, however, the terminal half-life (34.7 versus 57.2 min) and mean residence time (73.3 versus 99.3 min) were significantly shorter, area under the plasma concentration-time curve from time zero to time infinity (AUC, 1930 versus 2680 microg min/ml) was significantly smaller, and time-averaged renal (2.24 versus 1.21 ml/min/kg) and total body (CL, 4.98 versus 3.65 ml/min/kg) clearances were significantly faster than those in control rats. This could be mainly due to significantly faster renal clearance and at least partly due to increased cytochrome P450 1A2 activity by cysteine supplementation. After intravenous administration to rats with PCMC, the total amount of 8-hr urinary excretion of unchanged azosemide was significantly greater (457 versus 305 microg/g body weight), however, the 8-hr urine output (15.3 versus 31.1 ml/g kidney) was not significantly different between control rats and rats with PCMC. This could be due to the fact that urine output seemed to reach an upper plateau from 10 mg/kg dose of azosemide in rats.

Impaired angiogenesis in the aging kidney: vascular endothelial growth factor and thrombospondin-1 in renal disease

We investigated the relationship of changes in the microvasculature to age-related structural and functional changes in the kidney to determine whether there was evidence of impaired angiogenesis and whether the loss of microvasculature could be accounted for by changes in the local production of angiogenic or antiangiogenic factors. Glomerular and peritubular capillary number, density, and endothelial cell proliferation were determined in aging (24 months; n = 9) and young (3 months; n = 8) rat kidneys and correlated with renal functional and structural changes and alterations in renal expression of vascular endothelial growth factor (VEGF) and thrombospondin-1 (TSP-1). Aging rats showed a focal decrease in both peritubular capillary (peritubular capillary staining, 5.4% +/- 1.8% versus 11.3% +/- 2.0% per 100 tubules; rarefaction index, 10.6% +/- 4.6% versus 0.6% +/- 0.1%, aging versus young rats; P < 0.05 and P: < 0.001, respectively) and glomerular capillary loops (27.3 +/- 6.9 versus 50.7 +/- 7.4/glomerulus, aging versus young rats; P < 0.001). The number of proliferating endothelial cells was decreased in aging rats compared with young rats (glomerular, 0.04 +/- 0.01 versus 0.15 +/- 0.03 positive cells/glomerular cross-section; peritubular, 0.7 +/- 0.2 versus 4.3 +/- 2.6 positive cells/mm(2); P < 0.05). In the aging kidney, VEGF expression was focally increased in the cortex compared with young rats, whereas a profound decrease was observed in the outer and inner medulla (total area of VEGF expression, 19.2% +/- 11.4% versus 39.3% +/- 7.6%; P < 0.05). Tubular VEGF expression correlated with peritubular capillary density (r(2) = 0.57; P < 0.01) and inversely correlated with tubular osteopontin (r(2) = -0.55; P < 0.05) and macrophage infiltration (r(2) = -0.64; P < 0.01). TSP-1 staining was increased in the glomeruli and tubulointerstitium of the aging rats. Glomerular TSP-1 score correlated inversely with glomerular capillary number (r(2) = -0.89; P < 0.001). Tubulointerstitial TSP-1 also correlated with percentage of positive staining of peritubular capillary (r(2) = -0.59; P < 0.001). Glomerular capillary number showed significant correlation with glomerulosclerosis score, as well as with 24-hour urinary protein excretion. Peritubular capillary density also inversely correlated with interstitial fibrosis score and urinary protein excretion. In conclusion, glomerular and peritubular capillary loss in the aging kidney correlate with alterations in VEGF and TSP-1 expression and also with the development of glomerulosclerosis and tubulointerstitial fibrosis. These findings suggest that impaired angiogenesis associated with progressive loss in renal microvasculature may have a pivotal role in age-related nephropathy.

Expression of cytochrome P-450s and glutathione S-transferases in the rat liver during water deprivation: effects of glucose supplementation

Pharmacokinetic profiles of therapeutic agents change in dehydrated animals. The present study was designed to determine the expression of xenobiotic-metabolizing enzymes in the rat liver and the effect of glucose supplementation during water deprivation. Deprivation of water intake, which reduced food intake, resulted in no significant change in the cytochrome P-450 1A2, 2B1/2, 2C11 and 3A1/2 expression. Cytochrome P-450 2E1, however, was three-fold induced with an increase in the mRNA. Rehydration of 48-h water-deprived rats for the next 24 h with free access to foods restored the P-450 2E1 level to that of the control, although rehydration with 20% food supply failed to normalize the P-450 2E1 expression. Water deprivation caused a reduction in the plasma insulin level, which was prevented by rehydration with a sufficient food supply. The plasma insulin level was inversely related to the P-450 2E1 expression. Glucose feeding instead of foods during dehydration prevented P-450 2E1 induction in the absence of recovering the plasma insulin level. Western blot analysis revealed that the hepatic rGSTA2 level was 30% decreased in dehydrated rats, whereas the rGSTA3, M1 and M2 expression was not affected. Suppression of rGSTA2 accompanied a reduction in the mRNA. Glucose feeding further reduced rGSTA2 expression. The data indicated that expression of major P-450s and glutathione S-transferases, except P-450 2E1, was not greatly affected by water deprivation and that the P-450 2E1 induction and a decrease in plasma insulin resulted from the reduction in food intake but not from dehydration per se. Glucose supplementation restored P-450 2E1 expression but further suppressed rGSTA2 expression during water deprivation.

Comparative mutational analysis of cis-acting RNA signals for translational frameshifting in HIV-1 and HTLV-2

Human immunodeficiency virus type 1 (HIV-1) and human T cell leukemia virus type II (HTLV-2) use a similar mechanism for -1 translational frameshifting to overcome the termination codon in viral RNA at the end of the gag gene. Previous studies have identified two important RNA signals for frameshifting, the slippery sequence and a downstream stem-loop structure. However, there have been somewhat conflicting reports concerning the individual contributions of these sequences. In this study we have performed a comprehensive mutational analysis of the cis-acting RNA sequences involved in HIV-1 gag-pol and HTLV-2 gag-pro frameshifting. Using an in vitro translation system we determined frameshifting efficiencies for shuffled HIV-1/HTLV-2 RNA elements in a background of HIV-1 or HTLV-2 sequences. We show that the ability of the slippery sequence and stem-loop to promote ribosomal frameshifting is influenced by the flanking upstream sequence and the nucleotides in the spacer element. A wide range of frameshift efficiency rates was observed for both viruses when shuffling single sequence elements. The results for HIV-1/HTLV-2 chimeric constructs represent strong evidence supporting the notion that the viral wild-type sequences are not designed for maximal frameshifting activity but are optimized to a level suited to efficient viral replication.

Hairless mouse epidermal antioxidants and lipid peroxidation assessed by He-Ne laser

BACKGROUND AND OBJECTIVE

To evaluate the possibility of oxygen radical damage in the skin after He-Ne laser irradiation according to dose intensity and time.

STUDY DESIGN/MATERIALS AND METHODS

The He-Ne laser (lambda = 632.8, 10 mW) was used on the skin of mice with 1, 3, and 5 joule (J/cm2) dose rates for 1, 5, and 7 days in each case, and the results were compared with normal and anesthetic nonirradiated skins. The efficacy was determined by the formation of thiobarbituric acid-reactive substances (TBARS) in a 10-minute period and expressed as a concentration of malondialdehyde (MDA) from the lipid peroxidation of epidermal tissue, and total superoxide dismutases (SODs) and catalase activities, correlated with histologic biopsies.

RESULTS

Data from epidermal SODs, catalase activity and the degree of lipid peroxidation at low-power radiation showed that repeated exposure had led to the induction of free radical damage and of epidermal changes as confirmed by microscopic study. The application of the He-Ne laser at 1, 3, and 5 J intensity for 5 days caused a gradual increase in the SODs and catalase activities, while the levels of TBARS were slightly decreased in the mouse epidermis. However, these patterns were reversed after 3 and 5 J irradiations for 5 and 7 days laser treatment. Furthermore, microscopic examinations revealed that the laser-irradiated skin changed the release of stratum granule from epidermis to hair follicle, and produced blood vessel thrombosis of the dermal capillary plexus.

CONCLUSION

The presence of lipid peroxidation in the hairless mouse skin after exposure to He-Ne laser energy intensity of over 3 J for over 5 days was demonstrated. This lipid peroxidation could have been generated from oxygen free radicals. The histologic and oxidative enzymatic correlations on lipid peroxidation in the skin have provided a better understanding of He-Ne laser therapy-tissue interactions. It is possible to take advantage of these findings to evaluate pathologic skin conditions and effective laser dosage more efficiently.

Bioequivalence of two aceclofenac tablet formulations after a single oral dose to healthy male Korean volunteers

A bioequivalence study of aceclofenac tablets (test formulation: Dong-A, reference formulation: Airtal) was conducted in 16 healthy male Korean volunteers who received each medicine at a dose of 100 mg in a 2 x 2 crossover study. There was a one-week washout period between the doses. Plasma concentrations of aceclofenac were monitored by high-performance liquid chromatography over a period of 24 hours after the administration. AUCinf (the area under the plasma concentration-time curve from time zero to time infinity) was calculated by the linear-log trapezoidal method. Cmax (maximum plasma drug concentration) and tmax (time to reach Cmax) were compiled from the plasma concentration-time data. Analysis of variance was carried out using logarithmically transformed AUCinf and Cmax, and non-transformed tmax. There were no significant differences between the medications in AUCinf and Cmax. The point estimates and 90% confidence intervals for AUCinf (parametric) and Cmax (parametric) were 1.04 (0.93 to approximately 1.17) and 0.99 (0.91 to approximately 1.08), respectively, satisfying the bioequivalence criteria of the European Committee for Proprietary Medicinal Products and the US Food and Drug Administration Guidelines. The corresponding value for tmax was 0.75 (0.00 to approximately 1.00). Moreover, the modified Pitman-Morgan's adjusted F-test indicated that the bioavailabilities of aceclofenac in the 2 medications were comparable regarding intra- and interindividual variability. Therefore, these results indicate that the 2 medications of aceclofenac are bioequivalent and, thus, may be prescribed interchangeably.

Optimization of fermentation conditions for the production of bacterial cellulose by a newly isolated Acetobacter sp. A9 in shaking cultures

The optimum fermentation conditions for the production of cellulose by a newly isolated Acetobacter sp. A9 were determined by shaken cultures. The strain was able to produce cellulose at 25-30 degrees C with a maximum at 30 degrees C. Cellulose production occurred at pH 4.5-7.5 with a maximum at pH 6.5. The improved medium composition was 4% (w/v) glucose, 0.1% (w/v) yeast extract, 0.7% (w/v) polypeptone and 0.8% (w/v) Na(2)HPO(4).12H(2)O. Under these culture conditions, 3.8 g/l cellulose was produced after 7 days of cultivation, although this strain produced only 2.2 g/l in the standard medium. The addition of ethanol to the improved medium enhanced cellulose production: in an improved medium containing 1.4% (v/v) ethanol, cellulose production was 15.2 g/l, which was about four times higher than that without ethanol. Addition of ethanol was found to eliminate the spontaneous mutation of Acetobacter sp. A9.

Stimulation of homologous recombination through targeted cleavage by chimeric nucleases

Chimeric nucleases that are hybrids between a nonspecific DNA cleavage domain and a zinc finger DNA recognition domain were tested for their ability to find and cleave their target sites in living cells. Both engineered DNA substrates and the nucleases were injected into Xenopus laevis oocyte nuclei, in which DNA cleavage and subsequent homologous recombination were observed. Specific cleavage required two inverted copies of the zinc finger recognition site in close proximity, reflecting the need for dimerization of the cleavage domain. Cleaved DNA molecules were activated for homologous recombination; in optimum conditions, essentially 100% of the substrate recombined, even though the DNA was assembled into chromatin. The original nuclease has an 18-amino-acid linker between the zinc finger and cleavage domains, and this enzyme cleaved in oocytes at paired sites separated by spacers in the range of 6 to 18 bp, with a rather sharp optimum at 8 bp. By shortening the linker, we found that the range of effective site separations could be narrowed significantly. With no intentional linker between the binding and cleavage domains, only binding sites exactly 6 bp apart supported efficient cleavage in oocytes. We also showed that two chimeric enzymes with different binding specificities could collaborate to stimulate recombination when their individual sites were appropriately placed. Because the recognition specificity of zinc fingers can be altered experimentally, this approach holds great promise for inducing targeted recombination in a variety of organisms.

Prevention of c-Jun/activator protein-1 activation and microsomal epoxide hydrolase induction in the rat liver by cysteine during protein-calorie malnutrition

Protein-calorie malnutrition (PCM), a major global health problem, arises during protein and/or energy deficit due to disease and nutritional inadequacy. To date, cellular adaptive responses and gene expression associated with PCM remain poorly understood. In view of the primary role of the liver in energy conversion, the present study was designed to investigate changes in hepatic morphology and molecular alterations during PCM. PCM caused marked decreases in the cytoplasmic eosinophilic content and nuclear shrinkage in the hepatocytes with a decrease in glutathione content. The nuclear activator protein-1 (AP-1) complex was activated in the liver of PCM rats. AP-1-binding activity of nuclear extracts produced from PCM rats was reduced by the presence of anti-c-Jun antibody. Microsomal epoxide hydrolase (mEH), a phase II detoxifying enzyme, was 4-fold induced, with a 20-fold increase in the mRNA level during PCM. In contrast to the PCM-induced changes in hepatic morphology, PCM rats supplemented with cysteine showed an increase in the GSH level and well-preserved hepatic structures with mild fat degeneration. Cysteine supplementation inhibited the activation of AP-1 and the induction of mEH in PCM rats. These results provided evidence: (i) that PCM alters liver morphology with a decrease in the glutathione level; (ii) that cysteine may serve as a key element responsible for preserving hepatic morphology and maintaining the glutathione level; and (iii) that cysteine was active in preventing the activation of AP-1 and mEH induction in the liver during PCM.