Black patients with chronic hepatitis C have a lower sustained viral response rate than non-Blacks with genotype 1, but the same with genotypes 2/3, and this is not explained by more frequent dose reductions of interferon and ribavirin*.

In previous hepatitis C virus (HCV) treatment studies, Black patients not only had a lower sustained viral response (SVR) rate to interferon and ribavirin (RBV) than non-Black patients but also a higher frequency of HCV genotype 1 (GT-1) infection. The aim of this community-based study was to determine whether Black patients have a lower SVR rate independent of genotype. We prospectively enrolled 785 patients (24.8% Black, 71.5% White, 3.7% others) who received interferon alpha-2b 3 MU three times weekly + RBV 1000-1200 mg/day for 24 weeks (GT-2/3) or 48 weeks (GT-1). Black patients were more commonly infected with GT-1 (86.8%vs 64.8%, P < 0.001) and less frequently had an SVR compared with non-Black patients (8.4%vs 21.6%, P < 0.001). Within GT-1, Black patients had a lower SVR rate than non-Black patients (6.1%vs 14.1%, P = 0.004) but not within GT-2/3 (50.0%vs 36.5%, P = 0.47). Black patients had lower baseline haemoglobin levels (14.8 vs 15.3 g/dL, P < 0.001) and neutrophil counts (2900 vs 4100/mm(3), P < 0.001) and required more frequent dose reductions of RBV (29.8%vs 18.5%, P < 0.001) and interferon (4.7%vs 1.6%, P = 0.012). However, dose reductions were not associated with lower SVR rates while early treatment discontinuations were (2.9%vs 25.7%, P < 0.001). Independent predictors of SVR were GT-1 [odds ratio (OR) 0.33; 95% confidence interval (CI) 0.20-0.55; P < 0.001], Black race (OR 0.45; 95% CI 0.22-0.93; P = 0.030), and advanced fibrosis, stages 3 + 4 (OR 0.53; 95% CI 0.31-0.92; P = 0.023). In conclusion, Black patients infected with HCV GT-1 (but not GT-2/3) have a lower SVR rate than non-Black patients. This is not explained by their lower baseline haemoglobin levels and neutrophil counts that lead to higher rates of ribavirin and interferon dose reductions.

Bromfenac (Duract)-associated hepatic failure requiring liver transplantation.

Bromfenac sodium (Duract) is a phenylacetic acid-derived nonsteroidal anti-inflammatory agent introduced in the United States in 1997 and withdrawn in 1998. We describe the first case of fulminant hepatic failure associated with this agent treated successfully with liver transplantation. Similarities to hepatotoxicity with related agents is discussed.

Increased urinary F2-isoprostane excretion in alcoholic liver disease.

Free radical-induced lipid peroxidation (LP) is thought to be important in alcoholic liver disease (ALD), however, direct demonstration of increased LP in patients with ALD has been difficult. Quantification of F2-isoprostanes (F2-isoP), prostanoids produced by peroxidation of arachidonic acid, in plasma and urine are sensitive and specific indices of LP in vivo. To determine if LP is increased in ALD, 24-h urinary excretion of F2-isoPs were measured in 10 patients hospitalized because of ALD. The mean urinary excretion of the F2-isoP in the ALD patients' urine was 9.6+/-3.5 ng/mg creatinine, which was significantly elevated compared to controls' urinary excretion, which was 1.7+/-0.2 ng/mg creatinine (p<.01). The urinary excretion of F2-isoP decreased to 3.6+/-1.1 ng/mg creatinine as the patients improved clinically with abstinence over the 1-month period. These data suggest that lipid peroxidation, as assessed by this noninvasive method, is increased in patients with acute ALD and decreases with time as the patients improve clinically with abstinence.

The isoprostanes: unique prostaglandin-like products of free-radical-initiated lipid peroxidation.

The discovery of IsoPs as products of nonenzymatic lipid peroxidation has opened up new areas of investigation regarding the role of free radicals in human physiology and pathophysiology. The quantification of IsoPs as markers of oxidative stress status appears to be an important advance in our ability to explore the role of free radicals in the pathogenesis of human disease. An important need in the field of free-radical medicine is information regarding the clinical pharmacology of antioxidant agents. Because of the evidence implicating free radicals in the pathogenesis of a number of human diseases, large clinical trials are planned or underway to assess whether antioxidants can either prevent the development or ameliorate the pathology of certain human disorders. However, data regarding the most effective doses and combination of antioxidant agents to use in these clinical trials is lacking. As mentioned previously, administration of antioxidants suppresses the formation of IsoPs, even in normal individuals. Thus, measurement of IsoPs may provide a valuable approach to define the clinical pharmacology of antioxidants. In addition to being markers of oxidative stress, several IsoPs possess potent biological activity. The availability of additional IsoPs in synthetic form should broaden our knowledge concerning the role of these molecules as mediators of oxidant stress. Despite the fact that considerable information has been obtained since the initial report of the discovery of IsoPs [6], much remains to be understood about these molecules. With continued research in this area, we believe that much new information will emerge that will open up additional important new areas for future investigation.

Identification of free radical formation and F2-isoprostanes in vivo by acute Cr(VI) poisoning.

We previously reported the detection of a carbon-centered radical adduct of alpha-(4-pyridyl 1-oxide)-N-tert-butylnitrone (POBN) in the bile of rats acutely poisoned with Cr(VI) utilizing an electron spin resonance spin-trapping technique. These former studies suggested that the free radical metabolite was derived from a polyunsaturated fatty acid. The present studies were undertaken to further characterize this radical adduct and to determine whether its formation is associated with enhanced lipid peroxidation in vivo. This report demonstrates that electron spin resonance (ESR) spectra with hyperfine coupling constants aN of 15.71 G and of 2.90 G were present in bile from Cr(VI)-poisoned rats. We found out that virtually identical ESR spectra were obtained when authentic POBN-pentyl radical adducts generated from the reaction of POBN with either pentylhydrazine or linoleic or arachidonic acid with lipoxygenase were added to bile. The hyperfine coupling constants for the POBN-pentyl radical adducts added to bile were as follows: aN = 15.85 G and = 2.60 G for the reaction between pentylhydrazine and POBN; aN = 15.72 G and = 2.61 G for the reaction between arachidonic acid, lipoxygenase, and POBN; and aN = 15.85 G and = 2. 85 G for the reaction between linoleic acid, lipoxygenase, and POBN. In addition, the formation of this radical adduct was associated with lipid peroxidation as quantified by increases in F2-isoprostane levels in bile. These studies, therefore, provide additional evidence that acute Cr(VI) poisoning is associated with enhanced generation of F2-isoprostanes in vivo and tentatively identify the radical species that is produced as the POBN-pentyl radical adduct.

Experience with neoral versus sandimmune in primary liver transplant recipients.

We compared results using Neoral versus Sandimmune, each in combination with steroid and azathioprine immunosuppression, in primary liver transplantation recipients. There were 15 patients in each group with similar demographic distributions. Intravenous cyclosporine was stopped at 4.3 +/- 1.9 days in the Neoral group vs 7.8 +/- 4.9 days in the Sandimmune group. (P < 0.025). Cyclosporine levels in the first 10 days were higher (mean 306 ng/ml vs 231 ng/ml) in the Neoral group than the Sandimmune group (P < 0.05). The Neoral dose was less than the Sandimmune dose (mean 5.5 ng/kg per day vs 7.9 ng/kg per day) to achieve these levels in that time period (P < 0.05). Two patients (13%) experienced three episodes of biopsy-proven rejection in the Neoral group compared to nine patients (60%) with 12 episodes of rejection in the Sandimmune group (P < 0.025). Incidences of neurological and renal complications were similar between the groups. Infections requiring treatment were also similar. Liver function, renal function, and marrow function, evaluated at days 7, 14, 21, 28, and 2, 4, 6, and 12 months post-transplant, were not different between the groups. In summary, shorter use of intravenous cyclosporine and quicker stabilization of trough cyclosporine levels was achieved with Neoral than with Sandimmune. In the early post-transplant period, higher levels with lower doses were achieved with Neoral than with Sandimmune. In our experience, the incidence of rejection was lower with Neoral than with Sandimmune. There were similar lengths of hospitalization, mortality, adverse events, retransplantation, and similar liver, renal, and marrow function up to 1 year post-transplantation. Because of this experience, we continued to use Neoral in a total of 59 primary liver transplant recipients. We have not used intravenous cyclosporine in the last 44 patients. Follow-up was a mean of 11.4 months, ranging from 1 to 27 months. The incidence of rejection was 24% in these 59 patients compared to our historical experience of 70% using Sandimmune.

Comparison of formation of D2/E2-isoprostanes and F2-isoprostanes in vitro and in vivo--effects of oxygen tension and glutathione.

The isoprostanes (IsoPs) are bioactive prostaglandin-like compounds derived from the free-radical-catalyzed peroxidation of arachidonic acid in vitro and in vivo. IsoPs possessing either an F-type prostane ring (F2-IsoPs) or D/E-type prostane rings (D2/E2-IsoPs) are formed depending on whether IsoP endoperoxide intermediates undergo reduction or isomerization, respectively. Little, however, is known regarding factors influencing the formation of various classes of IsoPs, particularly D2/E2-IsoPs. Thus, studies were undertaken to examine the formation of D2/E2-IsoPs in relation to F2-Isops both in vitro and in vivo. In peroxidizing rat liver microsomes, the formation of D2/E2-IsoPs increased in a time- and oxygen-dependent manner and correlated with F2-IsoP generation and loss of precursor arachidonic acid, although the absolute amount of D2/E2-IsoPs formed exceeded by over 5-fold the levels of F2-IsoPs formed. Surprisingly, however, in liver tissue from rats exposed to an oxidant stress, levels of F2-IsoPs were up to 10-fold greater than those of D2/E2-IsoPs, suggesting that an endogenous process causes IsoP endoperoxide reduction in vivo. Addition of glutathione (GSH) to peroxidizing microsomes at concentrations from 0.01 to 5 mM increased the formation of F2-IsoPs at the expense of D2/E2-IsoPs. Boiling of microsomes did not alter the effect of GSH. Formation of D2/E2-IsoPs in liver tissue in vivo was greatly enhanced compared to F2-IsoPs in rats depleted of GSH. Thus, GSH modulates the formation of different classes of IsoPs in vitro and in vivo. Other thiols, including beta-mercaptoethanol, dithiothreitol, and cysteine, were able to substitute for GSH. These studies indicate that GSH promotes F2-IsoP formation and diminishes D2/E2-IsoP levels in vitro and in vivo by causing reduction of IsoP endoperoxides.

Nashville experience with liver transplantation in Veterans Administration patients.

In this study, we compared results of 28 liver transplants performed in 25 patients referred through the Veterans Administration with 82 transplants performed in 75 nonveteran patients. The evaluation and follow-up care was provided by the same team of physicians and nurses and the transplant procedure performed in the same hospital for both patient groups. There was a significantly greater incidence of hepatitis C and/or previous alcohol abuse in veteran compared with non-VA patients [23/25 (92%) vs 29/75 (39%); P < 0.05] and a greater incidence of native portal vein thrombosis [6/25 (24%) vs 2/75 (2.6%); P < 0.01], but no difference in Child's-Pugh score (10.8 vs 9.9) or UNOS listing status (mean status 2.7 vs 2.8). The increased incidence of native portal vein thrombosis did not appear to be solely related to previous alcohol abuse or hepatitis C, since only 1 of 29 (3.4%) non-VA patients with these etiologies had this finding. There was no difference in patient or graft survival between the VA and non-VA groups with overall actuarial 6-, 12-, and 18-month patient survival of 86, 84, and 83% and graft survival of 80, 78, and 77%. There was no difference in major complication rates but there was a significantly longer average hospital stay (27 +/- 31 vs 18 +/- 12 days; P < 0.05) in the VA compared with non-VA group. One patient with native portal vein thrombosis in the non-VA group developed portal vein thrombosis in the postoperative period. There was no documented recidivism in any patient with a history of prior substance abuse in either group. This study confirms that veteran patients have a higher incidence of hepatitis C and previous alcohol abuse as causes of liver disease, have a higher incidence of native portal vein thrombosis, and have longer mean hospital stays, but experience the same survival in the first 18 months compared with nonveteran patients.

Nonenzymatic free radical-catalyzed generation of thromboxane-like compounds (isothromboxanes) in vivo.

The isoprostanes (IsoPs) are novel bioactive prostaglandin-like compounds produced in vivo by free radical-catalyzed peroxidation of arachidonyl-containing lipids. Previously, we have identified IsoPs containing F-type and D- and E-type prostane rings that are formed by reduction and rearrangement of IsoP endoperoxide intermediates, respectively. We now explore whether thromboxane B2 (TxB2)-like compounds, termed B2-isothromboxanes (B2-IsoTxs), are formed by rearrangement of IsoP endoperoxides. Detection of these compounds was carried out using a stable isotope dilution mass spectrometric assay originally developed for quantification of cyclooxygenase-derived TxB2. Incubations of arachidonic acid with Fe/ADP/ascorbate for 30 min in vitro generated a series of peaks representing putative B2-IsoTx at levels of 62.4 +/- 21.0 ng/mg arachidonate. Using various chemical modification and derivatization approaches, it was determined that these compounds contained hemiacetal ring structures and two double bonds, as would be expected for B2-IsoTx. Analysis of the compounds by electron ionization mass spectrometry yielded multiple mass spectra similar to those of TxB2. B2-IsoTxs are also formed esterified to phospholipids; oxidation of arachidonyl-containing phosphatidylcholine in vitro followed by hydrolysis resulted in the release of large amounts of these compounds. To explore whether B2-IsoTxs are also formed in vivo, a well characterized animal model of lipid peroxidation consisting of orogastric administration of CCl4 to rats was used. Levels of B2-IsoTx esterified in lipids in the liver increased 41-fold from 2.5 +/- 0.5 to 102 +/- 30 ng/g of liver. In addition, circulating levels of free compounds increased from undetectable (<5 pg/ml) to 185 +/- 30 pg/ml after CCl4, a 37-fold increase. Thus, we have provided evidence that IsoTxs constitute another novel class of eicosanoids produced in vivo nonenzymatically by free radical-catalyzed lipid peroxidation. These studies thus expand our understanding of products of lipid peroxidation formed in vivo from the free radical-catalyzed peroxidation of arachidonic acid.

Evidence of free radical-mediated injury (isoprostane overproduction) in scleroderma.

OBJECTIVE: Free radical-induced oxidative stress with consequent lipid peroxidation and resultant tissue damage has been suggested as a potential mechanism of the pathogenesis of scleroderma. However, because reliable measurement of lipid peroxidation in vivo is difficult, it has not been possible to adequately examine this hypothesis. We have previously described a series of bioactive prostaglandin F2-like compounds, termed F2-isoprostanes, produced in vivo in humans by the non-cyclooxygenase, free radical-catalyzed, peroxidation of arachidonic acid and have shown them to be a reliable measure of lipid peroxidation in vivo. In the present study, we determined whether scleroderma is associated with enhanced oxidative stress. METHODS: As a measure of oxidative stress, we determined urinary concentrations of a tetranor-dicarboxylic acid metabolite of F2-isoprostanes (F2IP-M) by mass spectrometry in 8 patients with scleroderma (representing a wide spectrum of disease, including limited disease with refractory digital ulceration or pulmonary hypertension, and diffuse disease) and in 10 healthy control subjects. RESULTS: F2IP-M concentrations were significantly higher in patients with scleroderma (mean +/- SEM 3.41 +/- 0.64 ng/mg of creatinine) than in healthy controls (1.22 +/- 0.14 ng/mg of creatinine) (P = 0.002). These elevations occurred in patients with limited disease and in those with diffuse disease. CONCLUSION: The increased level of urinary F2IP-M supports the hypothesis that free radical-induced oxidative injury occurs in scleroderma and provides a biologic marker whose relationship to disease activity and disease therapy may be important. These findings may also provide a rationale for exploring whether antioxidant therapy may influence the natural course of the disease.

Isoprostanes--prostaglandin-like compounds formed in vivo independently of cyclooxygenase: use as clinical indicators of oxidant damage.

F2-isoprostanes are prostanoids produced independently of cyclooxygenase by free radical-catalyzed peroxidation of arachidonic acid-containing lipids. Quantification of F2-isoprostanes from biologic fluids and tissues represents an important advance in the detection and measurement of lipid peroxidation in vivo. In addition, efforts to understand both the biophysical effects of isoprostane containing lipids and the biologic effects of free isoprostanes should lead to a better understanding of the mechanisms responsible for oxidant stress-related alterations in homeostasis. Continued application of F2-isoprostane measurement in experimental models of free radical-induced injury and human disease may allow better design and evaluation of antioxidant therapeutic strategies.

Outcomes analysis for 50 liver transplant recipients: the Vanderbilt experience.

Healthcare reform has mandated scrutiny of the fiscal aspects of patient care as well as medical outcomes. Therefore, we reviewed our experience with 50 liver transplant recipients from a multidisciplinary collaborative transplant team. From February 1991 to July 1994, of 175 patients referred, 75 were formally evaluated for transplantation; 56 (76%) of these patients were accepted for transplantation; 50 patients underwent 53 transplants. Operative mortality of 6 per cent, retransplantation rate of 6 per cent, 6-month actuarial survival of 88 per cent, 1-year survival of 86 per cent, and the 2 and 3-year survival of 83 per cent were unchanged over time. Quality of life evaluated by the Karnofsky Performance Status was a mean of 55 pretransplant, 72 at 3 months, 79 at 6 months, 84 at 1 year, 88 at 2 years, and 95 at 3 years, demonstrating improved general health and functional rehabilitation after transplantation. Psychosocial Adjustment to Illness Scale scores demonstrated significant improvement following transplantation, improving most dramatically in the vocation environment, domestic environment, and sexual relationship domains. Postoperative length of stay has declined with an average of 28 days in 1991, 22 days in 1992, 19 days in 1993, and 14 days in 1994. Average total hospital, organ procurement, and physician charges for the transplantation hospitalization was $165,000. Average 91-92 hospital charges were $154,000 and were reduced in 93-95 to $103,000 (P < .05). We found that charges and length of stay decreased over time, while the outcome and quality of patient care was maintained. We believe the collaborative practice, case management, and revised patient care protocols are responsible.

Demonstration of halothane-induced hepatic lipid peroxidation in rats by quantification of F2-isoprostanes.

BACKGROUND: Halothane can be reductively metabolized to free radical intermediates that may initiate lipid peroxidation. Hypoxia and phenobarbital pretreatment in Sprague-Dawley rats increases reductive metabolism of halothane. F(2)-isoprostanes, a novel measure of lipid peroxidation in vivo, were used to quantify halothane-induced lipid peroxidation in rats. METHODS: Rats were exposed to 1% halothane or 14% O(2) for 2 h. Pretreatments included phenobarbital, isoniazid, or vehicle. Rats also were exposed to halothane, enflurane, and desflurane at 21% O(2). Lipid peroxidation was assessed by mass spectrometric quantification of F(2)-isoprostanes. RESULTS: Exposure of phenobarbital-pretreated rats to 1% halothane at 21% O(2) for 2 h caused liver and plasma F(2)-isoprostane concentrations to increase fivefold compared to nonhalothane control rats. This halothane-induced increase was enhanced by 14% O(2), but hypoxia alone had no significant effect. Alanine aminotransferase activity at 24 h was significantly increased only in the 1% halothane/14% O(2) group. The effect of cytochrome P450 enzyme induction on halothane-induced F(2)-isoprostane production and liver injury was determined by comparing the effects of isoniazid and phenobarbital pretreatment with no pretreatment under hypoxic conditions. Halothane caused 4- and 11-fold increases in plasma and liver F(2)-isoprostanes, respectively, in non-pretreated rats, whereas isoniazid pretreatment had no effect. Phenobarbital pretreatment potentiated halothane-induced lipid peroxidation with 9- and 20-fold increases in plasma and liver F(2)-isoprostanes, respectively. Alanine aminotransferase activity was increased only in this group. At ambient oxygen concentrations, halothane but not enflurane or desflurane, caused F(2)-isoprostanes to increase. CONCLUSIONS: Specific halothane-induced lipid peroxidation was demonstrated in Sprague-Dawley rats using quantification of F(2)-isoprostanes and was increased by hypoxia and phenobarbital pretreatment, but not isoniazid pretreatment.

Excretion of F2-isoprostanes in bile: a novel index of hepatic lipid peroxidation.

Lipid peroxidation is believed to be an important mechanism of liver injury caused by some xenobiotics. However, it has been difficult to demonstrate and quantify this process in vivo. Moreover, little is known about the disposition of lipids oxidized in the liver. F2-isoprostanes are prostanoids produced by nonenzymatic free radical-catalyzed peroxidation of arachidonic acid esterified to phospholipids. Hydrolysis of F2-isoprostanes from phospholipids by phospholipases yields free F2-isoprostanes. Excretion of F2-isoprostanes, both free and esterified to phospholipids, was measured in bile after administration of CCl4. The concentration of lipid-esterified F2-isoprostanes in bile exceeded that of free F2-isoprostanes. CCl4 caused a dose-dependent increase in biliary F2-isoprostane excretion that correlated better with the increase in liver F2-isoprostanes than it did with the increase in plasma F2-isoprostanes. Pretreatment with colchicine ameliorated CCl4-liver injury but did not affect baseline or CCl4-induced biliary F2-isoprostane excretion. Administration of diquat to selenium-deficient rats, which causes hepatic and renal necrosis, was associated with a 13-fold elevation of plasma F2-isoprostanes. However, both hepatic F2-isoprostane concentrations and biliary F2-isoprostane excretion were increased only threefold. These data suggest that quantification of F2-isoprostane excretion in bile may provide a sensitive and quantitative index of hepatic lipid peroxidation.

Liver and kidney necrosis in selenium-deficient rats depleted of glutathione.

BACKGROUND: Selenium and glutathione have interrelated oxidant defense roles in vivo. Experiments were carried out to determine the effect of glutathione depletion in selenium-deficient rats. EXPERIMENTAL DESIGN: Selenium-deficient and control rats were injected with phorone to deplete glutathione. Histologic assessment of liver and kidney injury was performed at 24 hours. In another experiment, glutathione depletion, lipid peroxidation, and liver injury were measured for 12 hours after phorone administration to determine their relationships with one another. In a final experiment, selenoproteins were correlated with protection against lipid peroxidation and liver necrosis. Selenium-deficient rats were injected with vehicle alone and with 5, 10, or 25 micrograms of selenium/kg. Twelve hours later, selenoproteins were measured in some of the rats, and phorone was injected into others. Liver injury and lipid peroxidation were assessed 6 hours after the phorone injection. RESULTS: Twenty-four hours after phorone administration (125 mg/kg), centrilobular hepatic necrosis and renal tubular necrosis were evident in selenium-deficient rats but not in controls. The time-course experiment revealed that phorone (250 mg/kg) caused sharp decreases in liver and kidney glutathione levels in both groups within 2 to 4 hours. Lipid peroxidation, as assessed by F2 isoprostane concentrations, in selenium-deficient animals. Liver necrosis, indicated by a rise in plasma ALT, took place in selenium-deficient rats but not in controls. Selenium injections into selenium-deficient rats increased selenoprotein P concentrations from 4% of control to as high as 39% but had little effect on glutathione peroxidase activities. Six hours after phorone administration, rats that had received selenium had no rise in ALT, and the rises in F2 isoprostanes were abolished or attenuated. CONCLUSIONS: We conclude that depletion of glutathione in selenium-deficient liver and kidney leads to necrosis in those organs associated with evidence of lipid peroxidation. Protection against this injury by selenium correlates with selenoprotein P concentration in plasma but not with glutathione peroxidase activity in tissues or in plasma. These findings raise the possibility that selenoprotein P protects cell membranes against oxidant injury and that glutathione is involved in that protection.

Purification, characterization, and N-terminal amino acid sequence of the adenylyl cyclase-activating protease from bovine sperm.

We previously reported the extraction of a factor from bovine sperm that activated adenylyl cyclases of rat brain and human platelets, and identified it as a trypsin-like protease that was referred to as "ninhibin." This proteolytic activity was purified to near homogeneity from an alkaline extract of washed sperm particles by sequential chromatography on p-aminobenzamidine agarose and CM-Sephadex. Purification was greater than 100-fold with nearly 30% recovery of protease activity exhibiting a major band of approximately 40 kDa. An approximately 45-kDa form of the protease was also evident in crude extracts and was preferentially isolated when the enzyme was prepared in the presence of a mixture of protease inhibitors. The larger form of the protease was substantially less effective in stimulating adenylyl cyclase than was the smaller form; it is likely to be a zymogen form from which the smaller, more active form is derived. Purified forms of acrosin and ninhibin exhibited similar mobilities on PAGE, similar capacities for activating adenylyl cyclase, similar patterns of proteolytic fragmentation, and similar immunoblot patterns obtained with an antibody against purified bovine acrosin. More importantly, the N-terminal amino acid sequence of bovine ninhibin was found to be identical with that of bovine acrosin and caprine acrosin and more than 75% identical with porcine acrosin. The data support the conclusion that the adenylyl cyclase-activating protease previously referred to as ninhibin is, in fact, acrosin.

Pathogenesis of diquat-induced liver necrosis in selenium-deficient rats: assessment of the roles of lipid peroxidation and selenoprotein P.

A dose of diquat below the amount injurious to selenium-replete animals causes lipid peroxidation and massive liver necrosis in selenium-deficient rats. The current study was undertaken to characterize the lipid peroxidation with respect to the liver injury and to correlate the presence of several selenoproteins with the protective effect of selenium. Lipid peroxidation was assessed by measurement of F2 isoprostanes. Diquat caused an increase in liver and plasma F2 isoprotanes. A gradient of these compounds was detected across the liver in some animals, indicating that this organ was a source of some of the plasma F2 isoprostanes. A time-course experiment showed that liver F2 isoprostane concentration increased before plasma alanine transaminase (ALT) levels rose. Selenium-deficient rats were injected with selenium doses from 2 to 50 micrograms/kg and studied 12 hours later. A dose of 10 micrograms/kg or more prevented diquat-induced lipid peroxidation and liver injury. This dose increased plasma selenoprotein P substantially, and a dose-response was present. Liver cellular and plasma glutathione peroxidase activities remained below 2% of their values in control rats for all selenium doses. In selenium-deficient rats given diquat, hepatic lipid peroxidation precedes hepatic necrosis and could therefore be an important mechanism of the necrosis. Selenoprotein P levels were increased by selenium injections, which protected against diquat injury, but glutathione peroxidase activity was not increased. This is consistent with selenoprotein P being the mediator of the selenium effect.

Pumpless respiratory assistance using a membrane oxygenator as an artificial placenta: a preliminary study in newborn and preterm lambs.

Newborns suffering from severe respiratory difficulties and not responding to conventional methods have been successfully treated by extracorporeal circulation with a membrane oxygenator (ECMO). However, the technique needs a highly specialized staff, excellent laboratory support, and continuous surveillance of the procedure to prevent complications. In a series of experiments on newborn and preterm lambs, we have investigated a relatively simpler technique of respiratory support that involves a pumpless arteriovenous bypass by cannulating both umbilical arteries and the umbilical vein. A highly efficient microporous membrane oxygenator (MO) with very low resistance was selected. This type of perfusion that mimics the placental circulation, besides providing an additional amount of oxygen to the blood, has proven to be very effective for CO2 extraction. Before its application in humans, however, improvements in the catheters to be inserted in the umbilical vessels, some modifications in the design of the MO, and improvements in the blood compatibility of all foreign surfaces in contact with blood are needed.

Release of markedly increased quantities of prostaglandin D2 from the skin in vivo in humans following the application of sorbic acid.

BACKGROUND AND DESIGN: Sorbic acid is a preservative that can induce cutaneous vasodilation characterized by erythema, urticaria, and stinging when applied topically to humans. Previous studies have suggested that prostaglandins may mediate the vasodilation, but the prostaglandin responsible has not been established. Recently, we have shown that cutaneous erythema similar to that associated with the application of sorbic acid is induced by topical administration of methylnicotinate and is mediated by the release of prostaglandin D2 (PGD2) from the skin. Therefore, we examined whether the cutaneous vasodilation induced by sorbic acid is also mediated by this prostaglandin in humans. RESULTS: Topical application of 1% sorbic acid to the forearms of four human volunteers resulted in 250- to 620-fold increases in levels of PGD2 and 15- to 58-fold increases in levels of the metabolite of PGD2, 9 alpha,11 beta-PGF2, in blood drawn from the antecubital vein draining the treated sites. There were no increases in the release of the other vasodilatory prostaglandins, PGE2 or prostacyclin (PGI2). The release of PGD2 in response to topically applied sorbic acid occurred in a dose-dependent manner and was not accompanied by a release of histamine, suggesting that the release of PGD2 was not from the mast cell. CONCLUSIONS: The cutaneous vasodilation that occurs following the administration of sorbic acid is primarily due to a release of PGD2 from a cellular source in the skin.