Diagnostic contribution of individual components of adrenal function tests to diagnose canine hyperadrenocorticism.

There is limited information regarding the value of constitutive components of the ACTH stimulation test (ACTHST) and low-dose dexamethasone suppression test (LDDST) including serum baseline cortisol (BC), difference between post-ACTH stimulation cortisol (PC) and BC (ΔACTHC), cortisol concentration 4h after dexamethasone administration (4HC), difference between 4HC and BC (Δ4C), and the difference between cortisol concentration 8h after dexamethasone administration and 4HC (Δ8C). Therefore, the objective of this study was to determine if these components can predict hyperadrenocorticism, pituitary-dependent hyperadrenocorticism (PDH), or functional adrenocortical tumor (FAT) in dogs. Cortisol concentrations were normalized, as fold change (FC), to the PC reference interval upper limit. A total of 1267 dogs were included, with hyperadrenocorticism diagnosed in 537 (PDH, n=356; FAT, n=28; undetermined, n=153) and excluded in 730. The area under the receiver operating curves for BC, ΔACTHC, 4HC, Δ4C, and Δ8C to predict hyperadrenocorticism were 0.76 (95% confidence interval (CI), 0.73-0.79), 0.91 (95% CI, 0.89-0.93), 0.83 (95% CI, 0.80-0.87), 0.55 (95% CI, 0.50-0.60), and 0.67 (95% CI, 0.62-0.72), respectively. A diagnostic limit of ≥0.78 FC for ΔACTHC had excellent sensitivity (1.00; 95% CI, 0.74-1.00), but poor specificity (0.67; 95% CI, 0.64-0.71), to predict FAT in dogs with a positive ACTHST. A diagnostic limit of ≥-0.26 FC for Δ4C had excellent sensitivity (1.00; 95% CI, 0.79-1.00), but poor specificity (0.21; 95% CI, 0.18-0.26), to predict FAT in dogs with a positive LDDST. In hyperadrenocorticoid dogs that have positive ACTHST or LDDST results, ΔACTHC or Δ4C, respectively, could be used to exclude FAT.

Effect of clinical signs, endocrinopathies, timing of surgery, hyperlipidemia, and hyperbilirubinemia on outcome in dogs with gallbladder mucocele.

Gallbladder mucocele (GBM) is a common extra-hepatic biliary syndrome in dogs with death rates ranging from 7 to 45%. Therefore, the aim of this study was to identify the association of survival with variables that could be utilized to improve clinical decisions. A total of 1194 dogs with a gross and histopathological diagnosis of GBM were included from 41 veterinary referral hospitals in this retrospective study. Dogs with GBM that demonstrated abnormal clinical signs had significantly greater odds of death than subclinical dogs in a univariable analysis (OR, 4.2; 95% CI, 2.14-8.23; P<0.001). The multivariable model indicated that categorical variables including owner recognition of jaundice (OR, 2.12; 95% CI, 1.19-3.77; P=0.011), concurrent hyperadrenocorticism (OR 1.94; 95% CI, 1.08-3.47; P=0.026), and Pomeranian breed (OR, 2.46; 95% CI 1.10-5.50; P=0.029) were associated with increased odds of death, and vomiting was associated with decreased odds of death (OR, 0.48; 95% CI, 0.30-0.72; P=0.001). Continuous variables in the multivariable model, total serum/plasma bilirubin concentration (OR, 1.03; 95% CI, 1.01-1.04; P<0.001) and age (OR, 1.17; 95% CI, 1.08-1.26; P<0.001), were associated with increased odds of death. The clinical utility of total serum/plasma bilirubin concentration as a biomarker to predict death was poor with a sensitivity of 0.61 (95% CI, 0.54-0.69) and a specificity of 0.63 (95% CI, 0.59-0.66). This study identified several prognostic variables in dogs with GBM including total serum/plasma bilirubin concentration, age, clinical signs, concurrent hyperadrenocorticism, and the Pomeranian breed. The presence of hypothyroidism or diabetes mellitus did not impact outcome in this study.

Thromboelastography in Dogs with Chronic Hepatopathies.

BACKGROUND: The coagulation status of dogs with liver disease is difficult to predict using conventional coagulation testing. HYPOTHESIS/OBJECTIVES: To evaluate thromboelastography (TEG) results and associations with conventional coagulation results and indicators of disease severity and prognosis in dogs with chronic hepatopathies (CH). ANIMALS: Twenty-one client-owned dogs. METHODS: Dogs with CH were prospectively (10 dogs) and retrospectively (11 dogs) enrolled from 2008 to 2014. Kaolin-activated TEG was performed and compared with reference intervals by t-tests or Mann-Whitney tests. Correlation coefficients for TEG results and conventional coagulation and clinicopathologic results were determined. Significance was set at P < .05. RESULTS: Dogs with CH had significant increases in R (5.30 min vs 4.33 min), K (3.77 min vs 2.11 min), and LY30 (4.77% vs 0.68%) and decreased angles (55.3° vs 62.4°). G value defined 9 of 21, 7 of 21, and 5 of 21 dogs as normocoagulable, hypercoagulable, and hypocoagulable, respectively. G and MA were correlated with fibrinogen (r = 0.68, 0.83), prothrombin time (PT; r = -0.51, -0.53), and activated partial thromboplastin time (aPTT; r = -0.50, -0.50). K was correlated with PT (r = 0.75) and protein C activity (r = -0.92). Angle was correlated with aPTT (r = -0.63). Clinical score was correlated with PT (r = 0.60), MA (r = -0.53), and R (r = -0.47). Dogs with hyperfibrinolysis (LY30 > 3.04%; 5 of 21) had significantly higher serum transaminase activities. Dogs with portal hypertension had significantly lower G, MA, and angle and prolonged, K, R, and PT. CONCLUSIONS AND CLINICAL RELEVANCE: Dogs with CH have variable TEG results. Negative prognostic indicators in CH correlate with hypocoagulable parameters on TEG. Hyperfibrinolysis in dogs with CH is associated with high disease activity.

Thromboelastographic Evaluation of Dogs with Acute Liver Disease.

BACKGROUND: Given the liver's pivotal role in hemostasis and fibrinolysis, the coagulopathy accompanying hepatic disease is complex. HYPOTHESIS/OBJECTIVES: To prospectively evaluate kaolin-activated thromboelastography (TEG) in dogs with acute liver disease (ALD) and compare with plasma-based coagulation tests. ANIMALS: Twenty-one dogs with a diagnosis of ALD based on recent onset of clinical signs accompanied by increases in serum bilirubin concentration and alanine aminotransferase activity. METHODS: Clinical presentation, CBC, serum biochemistry, platelet count, prothrombin time (PT), activated partial thromboplastin time (aPTT), and TEG analysis were evaluated in 21 dogs with a subset also having fibrinogen, antithrombin (AT) activity, protein C (PC) activity, d-dimers, and von Willebrand's factor (vWF) activity analyzed. A PT >1.5 times the upper limit of normal defined acute liver failure (ALF). RESULTS: Dogs with ALD had mean increases in R, K, LY30, PT, aPTT, and vWF activity, and decreases in angle, maximal amplitude (MA), G, AT activity, and PC activity. The TEG results defined dogs as hypocoagulable (11/21), normocoagulable (8/21), or hypercoagulable (2/21). Increases in LY30 defined 8/21 dogs as hyperfibrinolytic. Hypocoagulable and hyperfibrinolytic dogs had lower fibrinogen and PC activity than dogs without these abnormalities. Overall, ALF dogs had greater increases in K and LY30, and decreases in MA, G, and PC activity than dogs with less severe hepatic impairment. Results for MA and LY30 were positively correlated with serum bilirubin concentration and white blood cell count, and negatively correlated with serum cholesterol concentration. CONCLUSIONS AND CLINICAL IMPORTANCE: ALD dogs have a range of coagulation abnormalities that trend toward hypocoagulability and hyperfibrinolysis as functional impairment occurs.

Mars atmosphere. The imprint of atmospheric evolution in the D/H of Hesperian clay minerals on Mars.

The deuterium-to-hydrogen (D/H) ratio in strongly bound water or hydroxyl groups in ancient martian clays retains the imprint of the water of formation of these minerals. Curiosity's Sample Analysis at Mars (SAM) experiment measured thermally evolved water and hydrogen gas released between 550° and 950°C from samples of Hesperian-era Gale crater smectite to determine this isotope ratio. The D/H value is 3.0 (±0.2) times the ratio in standard mean ocean water. The D/H ratio in this ~3-billion-year-old mudstone, which is half that of the present martian atmosphere but substantially higher than that expected in very early Mars, indicates an extended history of hydrogen escape and desiccation of the planet.

Volatile, isotope, and organic analysis of martian fines with the Mars Curiosity rover.

Samples from the Rocknest aeolian deposit were heated to ~835°C under helium flow and evolved gases analyzed by Curiosity's Sample Analysis at Mars instrument suite. H2O, SO2, CO2, and O2 were the major gases released. Water abundance (1.5 to 3 weight percent) and release temperature suggest that H2O is bound within an amorphous component of the sample. Decomposition of fine-grained Fe or Mg carbonate is the likely source of much of the evolved CO2. Evolved O2 is coincident with the release of Cl, suggesting that oxygen is produced from thermal decomposition of an oxychloride compound. Elevated δD values are consistent with recent atmospheric exchange. Carbon isotopes indicate multiple carbon sources in the fines. Several simple organic compounds were detected, but they are not definitively martian in origin.

Thromboelastographic evaluation of dogs with congenital portosystemic shunts.

BACKGROUND: On plasma-based assays, dogs with congenital portosystemic shunts (CPSS) have changes in serum concentrations of both pro- and anticoagulant proteins, but how these abnormalities affect whole blood coagulation assays (eg, thromboelastography) are unknown. OBJECTIVES: To conduct kaolin-activated thromboelastography (TEG) analysis in dogs with CPSS and to compare TEG coagulation status with clinical presentation, routine serum biochemistry, and plasma-based coagulation tests. ANIMALS: Twenty-one client-owned dogs with CPSS confirmed by ultrasound examination or nuclear scintigraphy. METHODS: In a prospective study, signalment, clinical presentation, TEG analysis, CBC, serum biochemistry, and hemostatic tests (platelet count, prothrombin time [PT], activated partial thromboplastin time [aPTT], quantitative fibrinogen, antithrombin [AT] activity, protein C [PC] activity, d-dimers, and factor VIII activity) were analyzed in dogs with CPSS. RESULTS: Dogs with CPSS had significantly shorter K values and increased angle, maximum amplitude (MA), and G values compared with the reference population. On plasma-based coagulation testing, dogs with CPSS had significantly prolonged PT, lower platelet counts, lower AT and PC activities, and increased d-dimers and factor VIII activity. Evaluation of G value defined 9/21 dogs with CPSS as hypercoagulable. These dogs were more likely to have hepatic encephalopathy (HE) than CPSS dogs that had normal coagulation. CONCLUSIONS AND CLINICAL IMPORTANCE: TEG analysis detected hemostatic abnormalities consistent with a hypercoagulable state in some dogs with CPSS. The presence of a hypercoagulable state was 40 times more likely in dogs with symptomatic HE.

Portal vein thrombosis in 33 dogs: 1998-2011.

BACKGROUND: Portal vein thrombosis (PVT) has been reported infrequently in dogs. OBJECTIVES: To characterize the presentation, associated disease conditions, and outcome in dogs with PVT. ANIMALS: Client-owned dogs with a diagnosis of PVT and a complete medical record. METHODS: Records were retrospectively analyzed for presentation, history, physical examination, clinicopathologic data, diagnostic imaging, treatment, and outcome. RESULTS: Thirty-three dogs were included. Common clinical signs were vomiting, diarrhea, abdominal pain, ascites, and signs of hypovolemic shock. Associated disease conditions included hepatic (14/33), neoplastic (7/33), immune (5/33), and infectious (4/33) diseases, protein-losing nephropathy (3/33), hyperadrenocorticism (2/33), protein-losing enteropathy (1/33), and pancreatitis (1/33). Fourteen dogs were receiving glucocorticoids at the time of diagnosis. Twenty-nine dogs had at least 1 predisposing condition for venous thrombosis, and 11 had 2 or more. Thrombocytopenia (24/33), increased liver enzyme activity (23/33), and hypoalbuminemia (20/33) were common laboratory abnormalities. Clinical syndromes at the time of PVT diagnosis included shock (16/33), systemic inflammatory response syndrome (SIRS), (13/33) and disseminated intravascular coagulation (3/33). Twenty-four dogs had acute and 9 had chronic PVT. Multiple thrombi were found in 17/33 dogs. Nineteen dogs survived to discharge. Dogs treated with anticoagulant therapy were more likely, whereas those with acute PVT, multiple thromboses or SIRS were less likely to survive. CONCLUSIONS AND CLINICAL IMPORTANCE: Hepatic disease is a common pre-existing condition in dogs with PVT. PVT should be considered in dogs with risk factors for venous thrombosis presenting with abdominal pain, ascites, and thrombocytopenia. Studies evaluating anticoagulant therapy in the management of PVT are warranted.

cAMP-guanine exchange factor protection from bile acid-induced hepatocyte apoptosis involves glycogen synthase kinase regulation of c-Jun NH2-terminal kinase.

Cholestatic liver disorders are accompanied by the hepatic accumulation of cytotoxic bile acids that induce cell death. Increases in cAMP protect hepatocytes from bile acid-induced apoptosis by a cAMP-guanine exchange factor (cAMP-GEF)/phosphoinositide-3-kinase (PI3K)/Akt pathway. The aim of these studies was to identify the downstream substrate in this pathway and to determine at what level in the apoptotic cascade cytoprotection occurs. Since inhibitory phosphorylation of glycogen synthase kinase-3 (GSK) occurs downstream of PI3K/Akt and this phosphorylation has been implicated in cell survival, we conducted studies to determine whether GSK was downstream in cAMP-GEF/PI3K/Akt-mediated cytoprotection. Our results show that treatment of hepatocytes with the cAMP-GEF-specific analog, 4-(4-chlorophenylthio)-2'-O-methyladenosine-3',5'-cAMP, results in PI3K-dependent phosphorylation of GSK. Direct chemical inhibition of GSK in rat hepatocytes or human HUH7-NTCP cells with several structurally and functionally distinct inhibitors including bromoindirubin-3'-oxime (BIO), maleimides (SB216763, SB415286), thiadiazolidine derivatives, and LiCl attenuates apoptosis induced by glycochenodeoxycholate (GCDC). In addition, genetic silencing of the GSK ß isoform with small interfering RNA attenuates GCDC apoptosis in HUH7-NTCP cells. Adenoviral inhibition of the Rap1 blocks both cAMP-GEF-mediated cytoprotection against GCDC-induced apoptosis and Akt/GSK3ß phosphorylation. GCDC-induced phosphorylation of the proapoptotic kinase, c-Jun NH(2)-terminal kinase (JNK) is inhibited by GSK inhibition or cAMP-GEF activation. GCDC-induced apoptosis is accompanied by phosphorylation of the endoplasmic reticulum stress markers pIEF2α and IRE-1, and pretreatment with the cAMP-GEF analog or GSK inhibitors prevents this phosphorylation. Collectively, our results support the presence of a cAMP/cAMP-GEF/Rap1/PI3K/Akt/GSKß survival pathway in hepatocytes that inhibits bile acid-induced JNK phosphorylation.

Portal hypertension: pathophysiology, diagnosis, and treatment.

Portal hypertension (PH) is the result of increased vascular resistance in the portal circulation, increased portal venous blood flow, or both. In veterinary medicine, where portal pressure is seldom measured directly, the diagnosis of PH often is inferred from identification of associated complications including multiple acquired portosystemic shunts, ascites, and hepatic encephalopathy. Likewise, treatment of PH primarily is aimed at controlling these complications. The goal of this review is to provide an update on the pathophysiology, diagnosis, and treatment of PH. The review draws from information in the veterinary hepatology literature, reviews, and consensus statements in human hepatology and the literature on experimental models of PH.

Portal vein thrombosis in cats: 6 cases (2001-2006).

BACKGROUND: Portal vein thrombosis (PVT) in cats is sparsely reported. PURPOSE OF STUDY: To evaluate the clinical signs and diseases associated with PVT in cats. ANIMALS: 6 client-owned cats. METHODS: Medical records for cats with a portal vein thrombus diagnosed on abdominal ultrasound or at necropsy were reviewed. Signalment, historical data, underlying disorders, clinical findings, clinicopathologic and histopathologic data, diagnostic imaging findings, treatment, and outcome were recorded. RESULTS: All 6 cats identified with PVT also had hepatic disease. Evidence of a congenital portosystemic shunt was present in 3/6 cats. Two cats had primary or metastatic hepatic neoplasia. One cat had acute cholangitis, acute pancreatitis, and locally extensive acute centrilobular hepatic necrosis. Two cats were suspected to have acute thrombi and 4 cats had chronic thrombi. CONCLUSION AND CLINICAL SIGNIFICANCE: PVT might be an important concurrent finding in cats with hepatic disease.

Phosphoinositide 3-kinase, but not mitogen-activated protein kinase, pathway is involved in hepatocyte growth factor-mediated protection against bile acid-induced apoptosis in cultured rat hepatocytes.

We have previously shown that cAMP protects against hydrophobic bile acid-induced apoptosis in cultured rat hepatocytes through pathways dependent on activation of phosphoinositide 3-kinase and inhibition of mitogen activated protein kinase. Hepatocyte growth factor protects epithelial cells against apoptosis and activates both of these kinases in hepatocytes. We studied the effect of hepatocyte growth factor on glycochenodeoxycholate-induced apoptosis to determine whether hepatocyte growth factor protects hepatocytes against bile acid-induced apoptosis and whether the protective effect is mediated via phosphoinositide 3-kinase and/or mitogen-activated protein kinase pathways. Two-hour exposure of cultured rat hepatocytes to glycochenodeoxycholate resulted in apoptosis in 12.5 +/- 0.49% of the cells. Pretreatment with hepatocyte growth factor (50 ng/mL) decreased apoptosis by 50% to 70%. Hepatocyte growth factor cytoprotection was prevented by pretreatment with the phosphoinositide 3-kinase inhibitors, wortmannin (50 nmol/L) or Ly 294002 (40 micromol/L). Hepatocyte growth factor activated phosphoinositide 3-kinase dependent protein kinase B and mitogen-activated protein kinase. Pretreatment of hepatocytes with a mitogen-activated protein kinase inhibitor, U0126 (40 micromol/L) or an inhibitor of pp70(s6) kinase, rapamycin (100 nmol/L), had no effect on the growth factor's anti-apopotic effect. Treatment with hepatocyte growth factor resulted in mitogen-activated protein kinase-dependent phosphorylation of BAD on serine(112). In summary, hepatocyte growth factor protection against bile acid-induced apoptosis occurs via a phosphoinositide 3-kinase pathway and is not dependent on the mitogen-activated protein kinase pathway, phosphorylation of BAD on serine(112), or activation of p70(S6) kinase.

The detection of large HNO3-containing particles in the winter Arctic stratosphere.

Large particles containing nitric acid (HNO3) were observed in the 1999/2000 Arctic winter stratosphere. These in situ observations were made over a large altitude range (16 to 21 kilometers) and horizontal extent (1800 kilometers) on several airborne sampling flights during a period of several weeks. With diameters of 10 to 20 micrometers, these sedimenting particles have significant potential to denitrify the lower stratosphere. A microphysical model of nitric acid trihydrate particles is able to simulate the growth and sedimentation of these large sizes in the lower stratosphere, but the nucleation process is not yet known. Accurate modeling of the formation of these large particles is essential for understanding Arctic denitrification and predicting future Arctic ozone abundances.

Quantum-cascade laser measurements of stratospheric methane and nitrous oxide.

A tunable quantum-cascade (QC) laser has been flown on NASA's ER-2 high-altitude aircraft to produce the first atmospheric gas measurements with this newly invented device, an important milestone in the QC laser's future planetary, industrial, and commercial applications. Using a cryogenically cooled QC laser during a series of 20 aircraft flights beginning in September 1999 and extending through March 2000, we took measurements of methane (CH(4)) and nitrous oxide (N(2)O) gas up to ~20 km in the stratosphere over North America, Scandinavia, and Russia. The QC laser operating near an 8-mum wavelength was produced by the groups of Capasso and Cho of Bell Laboratories, Lucent Technologies, where QC lasers were invented in 1994. Compared with its companion lead salt diode lasers that were also flown on these flights, the single-mode QC laser cooled to 82 K and produced higher output power (10 mW), narrower laser linewidth (17 MHz), increased measurement precision (a factor of 3), and better spectral stability (~0.1 cm(-1) K). The sensitivity of the QC laser channel was estimated to correspond to a minimum-detectable mixing ratio for methane of approximately 2 parts per billion by volume.

Cell swelling-induced translocation of rat liver Na(+)/taurocholate cotransport polypeptide is mediated via the phosphoinositide 3-kinase signaling pathway.

Cell swelling stimulates phosphoinositide 3-kinase (PI3K) and mitogen-activated protein kinase (MAPK) in hepatocytes, and the PI3K signaling pathway is involved in cAMP-mediated translocation of sinusoidal Na(+)/taurocholate (TC) cotransporter (Ntcp) to the plasma membrane. We determined whether cell swelling also stimulates TC uptake and Ntcp translocation via the PI3K and/or MAPK signaling pathway. All studies were conducted in isolated rat hepatocytes. Hepatocyte swelling induced by hypotonic media resulted in: 1) time- and medium osmolarity-dependent increases in TC uptake, 2) an increase in the V(max) of Na(+)/TC cotransport, and 3) wortmannin-sensitive increases in TC uptake and plasma membrane Ntcp mass. Hepatocyte swelling also induced wortmannin-sensitive activation of PI3K, protein kinase B, and p70(S6K). Rapamycin, an inhibitor of p70(S6K), inhibited cell swelling-induced activation of p70(S6K) but failed to inhibit cell swelling-induced stimulation of TC uptake. Because PD98095, an inhibitor of MAPK, did not inhibit cell swelling-induced increases in TC uptake, it is unlikely that the effect of cell swelling on TC uptake is mediated via the MAPK signaling pathway. Taken together, these results indicate that 1) cell swelling stimulates TC uptake by translocating Ntcp to the plasma membrane, 2) this effect is mediated via the PI3K, but not MAPK, signaling pathway, and 3) protein kinase B, but not p70(S6K), is a likely downstream effector of PI3K.

Ultrasonographic appearance and clinical findings in 14 dogs with gallbladder mucocele.

Fourteen dogs with enlarged gallbladders and immobile stellate or finely striated bile patterns on ultrasound are described. Smaller breeds and older dogs were overrepresented, with 4/14 Cocker Spaniels. Most dogs presented for nonspecific clinical signs such as vomiting, anorexia and lethargy. Abdominal pain, icterus and hyperthermia were the most common findings on physical examination. All dogs except one had serum elevation of total bilirubin and/or alkaline phosphatase, alanine aminotransferase and gamma glutamyl transferase. All dogs were diagnosed with a gallbladder mucocele upon histologic and/or macroscopic evaluation. Ultrasonographically, mucoceles are characterized by the appearance of the stellate or finely striated bile patterns and differ from biliary sludge by the absence of gravity dependent bile movement. On ultrasound, gallbladder wall thickness and wall appearance were variable and nonspecific. The cystic or common bile duct were normal sized in 5 dogs although all 5 had evidence of biliary obstruction at surgery or necropsy. Loss of gallbladder wall integrity and/or gallbladder rupture were present in 50% of the dogs, all located in the fundus. Gallbladder wall discontinuity on ultrasound indicated rupture whereas neither bile patterns predicted the likelihood of gallbladder rupture. Pericholecystic hyperechoic fat or fluid were suggestive of but not diagnostic for a gallbladder rupture. Cholecystectomy appears to be an appropriate treatment for mucoceles, if not to treat a gallbladder rupture, at least in most dogs to prevent it since gallbladder wall necrosis was identified by histology in 9 of 10 dogs. Mucosal hyperplasia was present in all gallbladders examined histologically. Positive aerobic bacterial culture was obtained from bile in 6 of 9 dogs. Cholecystitis was diagnosed histologically in 5 dogs and 4 dogs had signs of gallbladder infection solely upon bacterial bile culture. Gallbladder infection was not present with all the mucoceles suggesting that biliary stasis and mucosal hyperplasia may be the primary factors involved in mucocele formation. Based on the results of our study, we suggest two alternate courses of action in the presence of a distended gallbladder with an immobile ultrasonographic stellate or finely striated bile pattern: a cholecystectomy when clinical or biochemical signs of hepatobiliary disease are present or a medical treatment (antibiotics and choleretics) and patient monitoring by follow-up ultrasound examinations when the patient does not have clinical or biochemical abnormalities. An aerobic bile culture should be obtained in all patients, by ultrasound-guided fine needle aspirate or at surgery.

Role of the PI3K/PKB signaling pathway in cAMP-mediated translocation of rat liver Ntcp.

cAMP stimulates Na(+)-taurocholate (TC) cotransport by translocating the Na(+)-TC-cotransporting peptide (Ntcp) to the plasma membrane. The present study was undertaken to determine whether the phosphatidylinositol-3-kinase (PI3K)-signaling pathway is involved in cAMP-mediated translocation of Ntcp. The ability of cAMP to stimulate TC uptake declined significantly when hepatocytes were pretreated with PI3K inhibitors wortmannin or LY-294002. Wortmannin inhibited cAMP-mediated translocation of Ntcp to the plasma membrane. cAMP stimulated protein kinase B (PKB) activity by twofold within 5 min, an effect inhibited by wortmannin. Neither basal mitogen-activated protein kinase (MAPK) activity nor cAMP-mediated inhibition of MAPK activity was affected by wortmannin. cAMP also stimulated p70(S6K) activity. However, rapamycin, an inhibitor of p70(S6K), failed to inhibit cAMP-mediated stimulation of TC uptake, indicating that the effect of cAMP is not mediated via p70(S6K). Cytochalasin D, an inhibitor of actin filament formation, inhibited the ability of cAMP to stimulate TC uptake and Ntcp translocation. Together, these results suggest that the stimulation of TC uptake and Ntcp translocation by cAMP may be mediated via the PI3K/PKB signaling pathway and requires intact actin filaments.

Airborne laser infrared absorption spectrometer (ALIAS-II) for in situ atmospheric measurements of N2O, CH4, CO, HCl, and NO2 from balloon or remotely piloted aircraft platforms.

The Airborne Laser Infrared Absorption Spectrometer II (ALIAS-II) is a lightweight, high-resolution (0.0003-cm(-1)), scanning, mid-infrared absorption spectrometer based on cooled (80 K) lead-salt tunable diode laser sources. It is designed to make in situ measurements in the lower and middle stratosphere on either a balloon platform or high-altitude remotely piloted aircraft. Chemical species that can be measured precisely include long-lived tracers N(2)O and CH(4), the shorter-lived tracer CO, and chemically active species HCl and NO(2). Advances in electronic instrumentation developed for ALIAS-I, with the experience of more than 250 flights on board NASA's ER-2 aircraft, have been implemented in ALIAS-II. The two-channel spectrometer features an open cradle, multipass absorption cell to ensure minimal contamination from inlet and surfaces. Time resolution of the instrument is

Role of protein phosphatases in cyclic AMP-mediated stimulation of hepatic Na+/taurocholate cotransport.

Cyclic AMP has been proposed to stimulate Na+/taurocholate (TC) cotransport in hepatocytes by translocating Na+/TC cotransport polypeptide (Ntcp) to the plasma membrane and to induce Ntcp dephosphorylation. Whether protein phosphatases 1 and 2A (PP1/2A) are involved in the regulation of Na+/TC cotransport by cAMP was investigated in the present study. Okadaic acid and tautomycin, inhibitors of PP1/2A, inhibited cAMP-mediated increases in TC uptake and cytosolic [Ca2+], and only tautomycin inhibited basal TC uptake. Removal of cAMP reversed cAMP-mediated increases in TC uptake and plasma membrane Ntcp mass. Okadaic acid alone increased Ntcp phosphorylation without affecting Ntcp mass in plasma membranes and homogenates. In the presence of okadaic acid, cAMP failed to increase plasma membrane Ntcp mass, induce Ntcp dephosphorylation, and decrease endosomal Ntcp mass. Phosphorylated Ntcp was detectable in endosomes isolated from okadaic acid-treated hepatocytes but not in endosomes from control and cAMP-treated hepatocytes. PP1 was found to be enriched in plasma membranes, whereas PP2A was mostly in the cytosol. Cyclic AMP did not activate either PP1 or PP2A, whereas okadaic acid inhibited primarily PP2A. These results suggest that 1) the effect of cAMP on Na+/TC cotransport is not mediated via either PP1 or PP2A; rather, cAMP-mediated signaling pathway is maintained by PP2A and inhibition of PP2A overrides cAMP-mediated effects, and 2) okadaic acid, by inhibiting PP2A, inhibits cAMP-mediated increases in Na+/TC cotransport by decreasing the ability of cAMP to increase cytosolic [Ca2+]. It is proposed that cAMP-mediated dephosphorylation of Ntcp leads to an increased retention of Ntcp in the plasma membrane, and okadaic acid, by inhibiting PP2A, inhibits cAMP-mediated stimulation of Na+/TC cotransport by reversing the ability of cAMP to increase cytosolic [Ca2+] and to induce Ntcp dephosphorylation.

Hepatocellular toxicosis associated with administration of carprofen in 21 dogs.

A diagnosis of hepatocellular toxicosis attributable to carprofen administration was made in 21 dogs on the basis of development of clinical signs and clinicopathologic abnormalities associated with hepatic disease and histopathologic documentation of hepatic necrosis. Clinical signs of toxicosis were anorexia, vomiting, and icterus. Hyperbilirubinemia and high serum activities of alanine transaminase, alkaline phosphatase, and aspartate transaminase were the most notable clinicopathologic abnormalities. In 7 of 9 dogs in which urinalyses were performed, abnormalities suggestive of renal tubular disease were detected. Clinical course of toxicosis was variable; however, most dogs had resolution of clinical signs and improvement or resolution of biochemical abnormalities with discontinuation of the drug and administration of supportive care. As with any medication, clients should be informed of possible adverse effects and reactions associated with administration of carprofen. In the event of those signs, clients should be instructed to immediately discontinue administration of carprofen to their dog and contact their veterinarian.