Impact of electronic reminder systems on hepatitis C screening in primary care.

Screening for hepatitis C virus (HCV) was recommended in 2012 by the Centers for Disease Control (CDC) for the population born between 1946 and 1965. Reminder systems are effective at promoting HCV screening, but the yield of positive tests among various population subgroups and the linkage to specialty HCV treatment is not well understood. We sought to determine: (i) the effect of the CDC recommendation alone, and the effect of an electronic medical record (EMR) reminder on the proportion of the population screened; (ii) the yield of positive HCV tests as screening strategies have evolved, and according to a patient's history of serum aminotransferase testing; (iii) the proportion of positive cases followed up for HCV treatment. This retrospective cohort study included 60 000 primary care patients at a northeast US academic medical centre serving an urban and rural population in which an EMR reminder was instituted in 2014. Results demonstrated an increase in proportion tested for HCV from 12% prior to the CDC recommendation to 37% after the reminder system. The yield of positive HCV antibody (HCV Ab) tests decreased from 7% in the "case-finding" era to 1.6% after the EMR reminder prompted screening of a lower risk population (P < .001). Patients with a history of abnormal aminotransferase tests had a fivefold higher rate of positive HCV Ab testing (6.7% vs 1.5%, P < .001). Ninety per cent of patients with confirmed HCV infection were seen in specialty care.

Tardive dyskinesia presenting as gastrointestinal disorder.

Tardive dyskinesia is an involuntary movement disorder characterized by choreoathetoid movements, tics, grimaces, and dystonia secondary to the prolonged use of neuroleptic medication. The characteristic abnormal movements associated with tardive dyskinesia involve orofacial muscle dyskinesias as well as the limbs and trunk. Involvement of the respiratory musculature and esophagus has rarely been reported. The authors describe a case of tardive dyskinesia presenting with gastrointestinal symptoms. This case illustrates that neuroleptic side effects and the syndrome of tardive dyskinesia need to be considered in the assessment of gastrointestinal complaints in patients with long-term neuroleptic exposure.

Fulminant hepatic failure.

Fulminant hepatic failure is a devastating complication of viral hepatitis, hepatotoxic exposures, and a variety of other acute liver diseases. Although this syndrome is associated with high mortality, liver transplantation can be life saving. This article discusses the medical management of fulminant hepatic failure and emphasizes complications, determinants of survival, and patient selection for liver transplantation.

Fatigue is highly associated with poor health-related quality of life, disability and depression in newly-diagnosed patients with inflammatory bowel disease, independent of disease activity.

BACKGROUND: Fatigue is common in Crohn's disease (CD) and ulcerative colitis (UC). Data on fatigue in newly diagnosed patients are unavailable. AIM: To report prevalence of fatigue in newly diagnosed CD and UC patients and examine its association with health-related quality of life (HRQOL), depression and disability. METHODS: The Ocean State Crohn's and Colitis Area Registry (OSCCAR) is a statewide cohort of newly diagnosed inflammatory bowel disease patients in Rhode Island. Fatigue was assessed using the Functional Assessment of Chronic Illness Therapy-Fatigue Scale. Patients were administered instruments measuring HRQOL, overall disability and work impairment, and depression. RESULTS: Fatigue was prevalent in 26.4% of 220 subjects. Cohen's d effect sizes for fatigue were large: Short-Form 36 Health Survey mental health component (CD 1.5, UC 1.4) and physical health component (CD 1.4, UC 1.4), EuroQol-5D valuation of current health state (CD 1.2, UC 1.0), Inflammatory Bowel Disease Questionnaire (CD 1.9, UC 1.6) and Patient Health Questionnaire depression scale (CD 1.8, UC 1.7). Fatigued patients reported more work impairment (Score difference: CD 29.5%, UC 23.8%) and activity impairment (score difference: CD 32.3%, UC 25.7%) on the Work Productivity and Activity Impairment Questionnaire. Fatigue's association with all scores remained highly significant despite controlling for disease activity. CONCLUSIONS: Fatigue is strongly associated with poor HRQOL, disability and depression similarly in CD and UC even when controlling for disease activity. Fatigue's association with a wide range of patient-reported outcome measures suggests that monitoring fatigue is a simple way to screen for overall disruption in patient life.

Convergent and parallel activation of low-conductance potassium channels by calcium and cAMP-dependent protein kinase.

K+ channels, which have been linked to regulation of electrogenic solute transport as well as Ca2+ influx, represent a locus in hepatocytes for the concerted actions of hormones that employ Ca2+ and cAMP as intracellular messengers. Despite considerable study, the single-channel basis for synergistic effects of Ca2+ and cAMP on hepatocellular K+ conductance is not well understood. To address this question, patch-clamp recording techniques were applied to a model liver cell line, HTC hepatoma cells. Increasing the cytosolic Ca2+ concentration ([Ca2+]i) in HTC cells, either by activation of purinergic receptors with ATP or by inhibition of intracellular Ca2+ sequestration with thapsigargin, activated low-conductance (9-pS) K+ channels. Studies with excised membrane patches suggested that these channels were directly activated by Ca2+. Exposure of HTC cells to a permeant cAMP analog, 8-(4-chlorophenylthio)-cAMP, also activated 9-pS K+ channels but did not change [Ca2+]i. In excised membrane patches, cAMP-dependent protein kinase (the downstream effector of cAMP) activated K+ channels with conductance and selectivity identical to those of channels activated by Ca2+. In addition, cAMP-dependent protein kinase activated a distinct K+ channel type (5 pS). These data represent the differential regulation of low-conductance K+ channels by signaling pathways mediated by Ca2+ and cAMP. Moreover, since low-conductance Ca(2+)-activated K+ channels have been identified in a variety of cell types, these findings suggest that differential regulation of K+ channels by hormones with distinct signaling pathways may provide a mechanism for hormonal control of solute transport and Ca(2+)-dependent cellular functions in the liver as well as other nonexcitable tissues.

Liver transplantation for fulminant hepatic failure.

In conclusion, the availability of liver transplantation has dramatically advanced the management of fulminant hepatic failure. A major responsibility of the gastroenterologist/hepatologist involved in the care of patients with liver failure is early decision making regarding likelihood of spontaneous recovery and consideration toward referral to a transplantation center. In particular, patients with exposure to drugs or toxins (other than acetaminophen); patients with presumed non-A, non-B hepatitis; children or older patients; patients with prolonged jaundice; profoundly jaundiced patients; or patients with severe coagulopathy should be given the highest consideration for urgent transplantation. Supportive care should take into account the potential complications of bleeding, sepsis, cerebral edema, renal failure, and respiratory failure. Such complications are the major limiting factors that prevent patients with fulminant hepatic failure from undergoing liver transplantation and contribute to the majority of postoperative deaths among patients who undergo transplantation. If these issues are heeded, and in light of emerging therapeutic modalities and surgical innovations, it is anticipated that ongoing improvement of the overall outcome of patients with fulminant hepatic failure will continue to be seen.

Alanine uptake activates hepatocellular chloride channels.

Cells involved in the retrieval and metabolic conversion of amino acids undergo significant increases in size in response to amino acid uptake. The resultant adaptive responses to cell swelling are thought to include increases in membrane K+ and Cl- permeability through activation of volume-sensitive ion channels. This viewpoint is largely based on experimental models of hypotonic swelling, but few mammalian cells experience hypotonic challenge in vivo. Here we have examined volume regulatory responses in a physiological model of cell-swelling alanine uptake in immortalized hepatocytes. Alanine-induced cell swelling was followed by a decrease in cell volume that was temporally associated with an increase in membrane Cl- currents. These currents were dependent both on alanine concentration and Na+, suggesting that currents were stimulated by Na+-coupled alanine uptake. Cl- currents were outwardly rectifying, exhibited an anion permeability sequence of I- > Br- > Cl-, and were inhibited by the Cl- channel blocker 5-nitro-2-(3-phenylpropylamino)benzoic acid, features similar to those reported for a widely distributed class of volume-sensitive anion channels evoked by experimental hypotonic stress. These findings suggest that volume-sensitive anion channels participate in adaptive responses to amino acid uptake and provide such channels with a new physiological context.

Regulation of cation-selective channels in liver cells.

In liver cells, cation-selective channels are permeable to Ca2+ and have been postulated to represent a pathway for receptor-mediated Ca2+ influx. This study examines the mechanisms involved in the regulation of these channels in a model liver cell line. Using patch-clamp recording techniques, it is shown that channel open probability is a saturable function of cytosolic [Ca2+], with half-maximal opening at 660 nm. By contrast, channel opening is not affected by membrane voltage or cytosolic pH. In intact cells, reduction of cytosolic [Cl-], a physiological response to Ca2+-mobilizing hormones and cell swelling, is also associated with an increase in channel opening. Finally, channel opening is inhibited by intracellular ATP through a mechanism that does not involve ATP hydrolysis. These findings suggest that opening of cation-selective channels is coupled to the metabolic state of the cell and provides a positive feedback mechanism for regulation of receptor-mediated Na+ and Ca2+ influx.

Mechanisms and functional role of intracellular pH regulation in hepatocytes.

Intracellular pH influences and is influenced by a diverse array of hepatocellular processes. It is regulated by the concerted action of three plasma membrane H+/HCO3- transporters that serve to buffer against both acidic (Na+/H+ exchange, Na+/HCO3- cotransport) and basic (Cl-/HCO3- exchange) metabolic challenges. The responsiveness of hepatocytes to these challenges is augmented by a regulatory interplay between pH-mediated changes in Vm and electrogenic Na+/HCO3- cotransport to maintain pHi and Vm within a range optimized to serve liver function. The cost is expenditure of metabolic energy to sustain increased activity of the Na+/K+ pump. The benefit is a dynamic servomechanism well-suited to the metabolic demands of hepatocytes, which may be found in future studies to be employed in other metabolically active epithelia as well.

Enzyme-linked sandwich immunoassay for insulin using laser fluorimetric detection.

Human serum samples are assayed for insulin by an enzyme-linked sandwich immunoassay. Horseradish peroxidase is used as an enzyme label for antibody, and enzyme activity is measured by means of the fluorogenic substrate, p-hydroxyphenylacetic acid. The product is detected by excitation of fluorescence with the 325-nm line of a continuous-wave helium/cadmium ion laser on line with reverse-phase high-pressure liquid chromatography. The incubation period is 90 min and the limit of detection of insulin is 30 pM, corresponding to 5 microunits/ml. This method correlates highly with radioimmunoassay, with coefficient of correlation r = 0.95.

Na(+)-Ca2+ exchange in cultured rat hepatocytes: evidence against a role in cytosolic Ca2+ regulation or signaling.

Plasma membrane Na(+)-Ca2+ exchange contributes importantly to the regulation of cytosolic Ca2+ concentration ([Ca2+]i) in excitable cells. Despite extensive study in excitable tissues, the role of this transporter in the regulation of [Ca2+]i in hepatocytes is unknown, and conflicting information has been reported regarding the presence of Na(+)-Ca2+ exchange in hepatocyte plasma membrane vesicles. We have therefore assessed the role of Na(+)-dependent Ca2+ transport in the regulation of [Ca2+]i in rat hepatocytes in primary culture under basal conditions and after exposure to vasopressin, a hormone that elevates [Ca2+]i. Ca2+ efflux, measured using 45Ca, did not differ in the presence or absence of extracellular Na+, either under basal conditions or in response to vasopressin. [Ca2+]i, measured using the Ca2(+)-sensitive dye fura-2, was not altered by transient or prolonged exposure to Na(+)-free media or by exposure to ouabain in concentrations sufficient to produce a five-fold elevation in intracellular Na+ concentration. The [Ca2+]i response to vasopressin was also unaffected by Na+ removal or ouabain. By contrast, in cultured rat cardiac myocytes, cells that possess Na(+)-Ca2+ exchange, transient or prolonged Na+ removal as well as ouabain exposure produced greater than fivefold increases in [Ca2+]i compared with controls. We conclude that Na(+)-Ca2+ exchange does not contribute to the regulation of [Ca2+]i in hepatocytes.

Cloning and functional expression of a liver isoform of the small conductance Ca2+-activated K+ channel SK3.

Small conductance Ca2+-activated K+ (SK) channels have been cloned from mammalian brain, but little is known about the molecular characteristics of SK channels in nonexcitable tissues. Here, we report the isolation from rat liver of an isoform of SK3. The sequence of the rat liver isoform differs from rat brain SK3 in five amino acid residues in the NH3 terminus, where it more closely resembles human brain SK3. SK3 immunoreactivity was detectable in hepatocytes in rat liver and in HTC rat hepatoma cells. Human embryonic kidney (HEK-293) cells transfected with liver SK3 expressed 10 pS K+ channels that were Ca2+ dependent (EC(50) 630 nM) and were blocked by the SK channel inhibitor apamin (IC(50) 0.6 nM); whole cell SK3 currents inactivated at membrane potentials more positive than -40 mV. Notably, the Ca2+ dependence, apamin sensitivity, and voltage-dependent inactivation of SK3 are strikingly similar to the properties of hepatocellular and biliary epithelial SK channels evoked by metabolic stress. These observations raise the possibility that SK3 channels influence membrane K+ permeability in hepatobiliary cells during liver injury.

Purinergic-independent calcium signaling mediates recovery from hepatocellular swelling: implications for volume regulation.

Swelling of hepatocytes and other epithelia activates volume-sensitive ion channels that facilitate fluid and electrolyte efflux to restore cell volume, but the responsible signaling pathways are incompletely defined. Previous work in model HTC rat hepatoma cells has indicated that swelling elicits ATP release, which stimulates P2 receptors and activates Cl(-) channels, and that this mechanism is essential for hepatocellular volume recovery. Since P2 receptors are generally coupled to Ca(2+) signaling pathways, we determined whether hepatocellular swelling affected cytosolic [Ca(2+)], and if this involved a purinergic mechanism. Exposure of HTC cells to hypotonic media evoked an increase in cytosolic [Ca(2+)], which was followed by activation of K(+) and Cl(-) currents. Maneuvers that interfered with swelling-induced increases in cytosolic [Ca(2+)], including extracellular Ca(2+) removal and intracellular Ca(2+) store depletion with thapsigargin, inhibited activation of membrane currents and volume recovery. However, the swelling-induced increases in cytosolic [Ca(2+)] were unaffected by either extracellular ATP depletion with apyrase or blockade of P2 receptors with suramin. These findings indicate that swelling elicits an increase in hepatocellular Ca(2+), which is essential for ion channel activation and volume recovery, but that this increase does not stem from activation of volume-sensitive P2 receptors. Collectively, these observations imply that regulatory responses to hepatocellular swelling involve a dual requirement for a purinergic-independent Ca(2+) signaling cascade and a Ca(2+)-independent purinergic signaling pathway.

Regulation of hepatic Na(+)-HCO3- cotransport and pH by membrane potential difference.

Hepatocytes possess several mechanisms for membrane acid-base transport, which work in concert to maintain intracellular pH (pHi) in a narrow physiological range, despite metabolic processes that produce and consume substantial quantities of H+ and HCO3-.Na(+)-H+ and Cl(-)-HCO3- exchangers contribute to recovery from intracellular acidosis and alkalosis, respectively, but are largely inoperative at physiological values of pHi. Recent studies indicate that hepatocytes also possess a mechanism for coupled transport of Na+ and HCO3- across the basolateral membrane. This appears to be the dominant pathway for membrane acid-base transport operative under basal conditions, mediates influx of Na+ and HCO3-, and is an important contributor to recovery from intracellular acidosis. In this review, the properties of hepatic Na(+)-HCO3- cotransport are described with emphasis on its effects on pHi and Na+ homeostasis and on the possible role of membrane potential difference as a signal modulating the rate of HCO3- influx and pHi of hepatocytes through effects on this transporter.

Transmembrane electrical potential difference regulates Na+/HCO3- cotransport and intracellular pH in hepatocytes.

We have examined the hypothesis that a regulatory interplay between pH-regulated plasma membrane K+ conductance (gK+) and electrogenic Na+/HCO3- cotransport contributes importantly to regulation of intracellular pH (pHi) in hepatocytes. In individual cells, membrane depolarization produced by transient exposure to 50 mM K+ caused a reversible increase in pHi in the presence, but not absence, of HCO3-, consistent with voltage-dependent HCO3- influx. In the absence of HCO3-, intracellular alkalinization and acidification produced by NH4Cl exposure and withdrawal produced membrane hyperpolarization and depolarization, respectively, as expected for pHi-induced changes in gK+. By contrast, in the presence of HCO3-, NH4Cl exposure and withdrawal produced a decrease in apparent buffering capacity and changes in membrane potential difference consistent with compensatory regulation of electrogenic Na+/HCO3- cotransport. Moreover, the rate of pHi and potential difference recovery was several-fold greater in the presence as compared with the absence of HCO3-. Finally, continuous exposure to 10% CO2 in the presence of HCO3- produced intracellular acidification, and the rate of pHi recovery from intracellular acidosis was inhibited by Ba2+, which blocks pHi-induced changes in gK+, and by 4-acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic acid, which inhibits Na+/HCO3- cotransport. These findings suggest that in hepatocytes, changes in transmembrane electrical potential difference, mediated by pH-sensitive gK+, play a central role in regulation of pHi through effects on electrogenic Na+/HCO3- cotransport.

Vasopressin increases cytosolic sodium concentration in hepatocytes and activates calcium influx through cation-selective channels.

A variety of hormonal agonists activate transmembrane Na+ and Ca2+ flux in hepatocytes, but the responsible mechanisms are poorly understood. We employed microfluorimetric and patch clamp recording techniques in hepatocytes to determine the effect of the hormone vasopressin on cytosolic Na+ concentration ([Na+]i) and to identify the transmembrane Na+ transport pathways activated by this agonist. Under basal conditions, [Na+]i, measured using the Na(+)-sensitive fluorophore sodium-binding benzofuran isophthalate, averaged 12.1 +/- 1.6 mM. Exposure to vasopressin rapidly increased [Na+]i by 8.3 +/- 0.9 mM. This increase was attributable to activation of Na+ influx. It occurred in the absence of solutes co-transported with Na+ and was not associated with activation of Na+/H+ antiport. In cell-attached membrane patches, vasopressin activated ion channels that carried inward positive current at the resting membrane potential. Further characterization in excised membrane patches revealed two classes of ion channels, with conductances of 16.0 +/- 2.8 and 30.9 +/- 3.1 picosiemens, respectively. Single channel currents reversed near 0 mV, and ion substitution studies demonstrated that each channel type was permeable to Na+, Ca2+, and K+ but not Cl-. These observations in hepatocytes indicate that vasopressin increases [Na+]i and activates cation-selective channels, which likely accounts for vasopressin-activated Na+ and Ca2+ influx.

Plasma membrane H(+)-HCO3- transport in rat hepatocytes: a principal role for Na(+)-coupled HCO3- transport.

Na(+)-coupled HCO3- transport has been demonstrated in the basolateral membrane of hepatocytes, but there is uncertainty regarding its stoichiometry or capacity compared with other mechanisms of H(+)-HCO3- transport. After preincubation in medium free of Na+, either in the presence or absence of HCO3(-)-CO2, rat hepatocytes in primary culture were reexposed to Na+ or HCO3(-)-CO2 alone or in combination. Transporter electrogenicity was assessed by measuring membrane potential difference (PD), and the relative capacities of Na(+)-coupled HCO3- transport, Cl(-)-HCO3- exchange, and Na(+)-H+ exchange were assessed by measuring the magnitude and rate of change of intracellular pH (pHi) using BCECF. In the absence of Na+, exposure to HCO3- alone had no consistent effect on PD or pHi. In the absence of HCO3-, reexposure to Na+ depolarized cells by 3 +/- 1 mV and caused an amiloride-inhibitable increase in pHi of 0.031 +/- 0.02 units/min. In the presence of HCO3-, reexposure to Na+ hyperpolarized cells by -14 +/- 5 mV and increased pHi at a rate of 0.133 +/- 0.11 units/min; both the hyperpolarization and alkalinization were inhibited by SITS but unaffected by amiloride. These changes in PD indicate that Na(+)-coupled HCO3- transport is electrogenic, consistent with coupling of more than one HCO3- to each Na+. Furthermore, SITS-inhibitable Na(+)-dependent alkalinization exceeds amiloride-inhibitable Na(+)-dependent alkalinization by an order of magnitude, suggesting that the transport capacity of Na(+)-coupled HCO3- transport exceeds that of Na(+)-H+ exchange.(ABSTRACT TRUNCATED AT 250 WORDS)

Severe hepatotoxicity associated with bromfenac sodium.

Subacute hepatitis and liver failure occurred in a 40-yr-old woman following a 1-month course of treatment with the nonsteroidal anti-inflammatory drug bromfenac. Serologies for hepatitis A, B, and C were negative, as were antinuclear antibodies and ceruloplasmin. A transjugular liver biopsy demonstrated submassive hepatic necrosis. The clinical course was complicated by encephalopathy, fluid retention, and spontaneous bacterial peritonitis, prompting consideration for liver transplantation. With supportive measures, jaundice and fluid retention resolved over a 3-month period. We conclude that prolonged use of bromfenac was the etiological agent in this case, and that this drug can cause severe hepatotoxicity resulting in liver failure.

Autocrine signaling through ATP release represents a novel mechanism for cell volume regulation.

Recovery of cell volume in response to osmotic stress is mediated in part by increases in the Cl- permeability of the plasma membrane. These studies evaluate the hypothesis that ATP release and autocrine stimulation of purinergic (P2) receptors couple increases in cell volume to opening of Cl- channels. In HTC rat hepatoma cells, swelling induced by hypotonic exposure increased membrane Cl- current density to 44.8 +/- 7.1 pA/pF at -80 mV. Both the rate of volume recovery and the increase in Cl- permeability were inhibited in the presence of the ATP hydrolase apyrase (3 units/ml) or by exposure to the P2 receptor blockers suramin and Reactive Blue 2 (10-100 microM). Cell swelling also stimulated release of ATP. Hypotonic exposure increased the concentration of ATP in the effluent of perfused cells by 170 +/- 36 nM in the presence of a nucleotidase inhibitor (P < 0.01). In whole-cell recordings with ATP as the charge carrier, cell swelling increased membrane current density approximately 30-fold to 16.5 +/- 10.4 pA/pF. These findings indicate that increases in cell volume lead to efflux of ATP through opening of a conductive pathway consistent with a channel, and that extracellular ATP is required for recovery from swelling. ATP may function as an autocrine factor that couples increases in cell volume to opening of Cl- channels through stimulation of P2 receptors.