Liver-specific FGFR4 knockdown in mice on an HFD increases bile acid synthesis and improves hepatic steatosis

Nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disease with increased risk in patients with metabolic syndrome. There are no FDA-approved treatments, but FXR agonists have shown promising results in clinical studies for NAFLD management. In addition to FXR, fibroblast growth factor receptor FGFR4 is a key mediator of hepatic bile acid synthesis. Using N-acetylgalactosamine-conjugated siRNA, we knocked down FGFR4 specifically in the liver of mice on chow or high-fat diet and in mouse primary hepatocytes to determine the role of FGFR4 in metabolic processes and hepatic steatosis. Liver-specific FGFR4 silencing increased bile acid production and lowered serum cholesterol. Additionally, we found that high-fat diet-induced liver steatosis and insulin resistance improved following FGFR4 knockdown. These improvements were associated with activation of the FXR-FGF15 axis in intestinal cells, but not in hepatocytes. We conclude that targeting FGFR4 in the liver to activate the intestinal FXR-FGF15 axis may be a promising strategy for the treatment of NAFLD and metabolic dysfunction.

Characterization of Viral Insulin-Like Peptides Reveals Unique White Adipose Tissue Specific Characteristics

The members of the insulin superfamily are well conserved across the evolution tree. We recently showed that four viruses in the Iridoviridae family possess genes that share high similarity with human insulin and IGF-1. By chemically synthesizing single chain (sc, IGF-1 like) forms of these viral insulin/IGF-1 like peptides (VILPs), we previously showed that sc VILPs have insulin/IGF properties in vitro and in vivo. However, characteristics of double chain (dc, insulin-like) VILPs remain unknown. In this study, we characterized dc forms of VILPs for Grouper iridovirus (GIV), Singapore grouper iridovirus (SGIV) and Lymphocystis disease virus-1 (LCDV-1). We showed that GIV and SGIV dcVILPs bind to both isoforms of human insulin receptor (IR-A, IR-B) and they bind to IGF-1R with a higher affinity than human insulin. These dcVILPs stimulate receptor phosphorylation and post-receptor signaling in vitro and in vivo. LCDV-1 dcVILP stimulated a weak response in in vitro signaling experiments, although we could not determine binding competition. Both GIV and SGIV dcVILPs stimulated glucose uptake in mice. In vivo infusion experiments in awake mice revealed that while insulin (2.5 mU/kg/min) and GIV dcVILP (125 mU/kg/min) stimulate a comparable glucose uptake in heart, skeletal muscle and brown adipose tissue, GIV dcVILP stimulates ~2 fold higher glucose uptake in white adipose tissue (WAT) compared to insulin. This is due to increased Akt phosphorylation and glucose transporter type 4 (GLUT4) expression compared to insulin specifically in WAT. Taken together, these results show that dc GIV and SGIV dcVILPs are active members of the insulin superfamily with unique characteristics. This observation evokes questions about their potential roles in human disease including diabetes and cancer. Elucidating the mechanism of tissue specificity for GIV dcVILP will help us to better understand insulin action and design new analogues that specifically target the tissues.

Oxidative stress causes heart failure with impaired mitochondrial respiration

Elderly people insidiously manifest the symptoms of heart failure, such as dyspnea and/or physical disabilities in an age-dependent manner. Although previous studies suggested that oxidative stress plays a pathological role in the development of heart failure, no direct evidence has been documented so far. In order to investigate the pathological significance of oxidative stress in the heart, we generated heart/muscle-specific manganese superoxide dismutase-deficient mice. The mutant mice developed progressive congestive heart failure with specific molecular defects in mitochondrial respiration. In this paper, we showed for the first time that the oxidative stress caused specific morphological changes of mitochondria, excess formation of superoxide (O(2)(*)(-)), reduction of ATP, and transcriptional alterations of genes associated with heart failure in respect to cardiac contractility. Accordingly, administration of a superoxide dismutase mimetic significantly ameliorated the symptoms. These results implied that O(2)(*)(-) generated in mitochondria played a pivotal role in the development and progression of heart failure. We here present a bona fide model for human cardiac failure with oxidative stress valuable for therapeutic interventions.

Phosphoinositide 3-kinase catalytic subunit deletion and regulatory subunit deletion have opposite effects on insulin sensitivity in mice

Studies ex vivo have shown that phosphoinositide 3-kinase (PI3K) activity is necessary but not sufficient for insulin-stimulated glucose uptake. Unexpectedly, mice lacking either of the PI3K regulatory subunits p85alpha or p85beta exhibit increased insulin sensitivity. The insulin hypersensitivity is particularly unexpected in p85alpha-/- p55alpha-/- p50alpha-/- mice, where a decrease in p110alpha and p110beta catalytic subunits was observed in insulin-sensitive tissues. These results raised the possibility that decreasing total PI3K available for stimulation by insulin might circumvent negative feedback loops that ultimately shut off insulin-dependent glucose uptake in vivo. Here we present results arguing against this explanation. We show that p110alpha+/- p110beta+/- mice exhibit mild glucose intolerance and hyperinsulinemia in the fasted state. Unexpectedly, p110alpha+/- p110beta+/- mice showed a approximately 50% decrease in p85 expression in liver and muscle. Consistent with this in vivo observation, knockdown of p110 by RNA interference in mammalian cells resulted in loss of p85 proteins due to decreased protein stability. We propose that insulin sensitivity is regulated by a delicate balance between p85 and p110 subunits and that p85 subunits mediate a negative role in insulin signaling independent of their role as mediators of PI3K activation.

ErbB2 is required for muscle spindle and myoblast cell survival

Signaling mediated by ErbB2 is thought to play a critical role in numerous developmental processes. However, due to the embryonic lethality associated with the germ line inactivation of erbB2, its role in adult tissues remains largely obscure. Given the expression of ErbB2 at the neuromuscular junction, we have created a muscle-specific knockout to assess its role there. This resulted in viable mice with a progressive defect in proprioception due to loss of muscle spindles. Interestingly, a partial reduction of ErbB2 levels also reduced the number of muscle spindles. Although histological analysis of the muscle revealed an otherwise normal architecture, induction of muscle injury revealed a defect in muscle regeneration. Consistent with these observations, primary myoblasts lacking ErbB2 exhibit extensive apoptosis upon differentiation into myofibers. Taken together, these results illustrate a dual role for ErbB2 in both muscle spindle maintenance and survival of myoblasts.

Molecular cloning of the human rad gene: gene structure and complete nucleotide sequence

We have isolated and sequenced human genomic DNA clones encoding the Ras-related GTP-binding protein, Rad. The gene spans 3.75 kb and consists of five exons and four introns. Translation initiates from the first of two in-frame methionine residues in the second exon. Several potential transcription cis-elements were revealed throughout the 1.7 kb 5'-flanking region, including 'E box' and CArG binding sites for regulators of transcription in muscle.

Signal transduction pathways for interleukin 4 and insulin in human hepatoma cells

IRS-1 has been found to relay the signals from the receptors for insulin, insulin-like growth factor-1, growth hormone, and many cytokines for the downstream effects in the various cell types tested. For interleukin 4 signaling, most studies were performed on hematopoietic cells and cell lines transfected with rat liver IRS-1 cDNA. In a liver cell lineage, IRS-1 expression has been found to be increased in hepatoma cells and hepatocytes in regenerating liver. To elucidate the possible function and the signal transduction pathway for interleukin 4, in comparison with insulin, in liver cells, we used the Hep 3B hepatoma cell line as a model system. Following insulin and interleukin 4 stimulation, rapid tyrosyl phosphorylation of IRS-1 occurred. Interleukin 4, but not insulin, stimulated the tyrosine phosphorylation of JAK1 and, to a lesser extent, JAK2. In contrast to the other cell types, the association of IRS-1 and Grb2 through the SH2 of Grb2 was demonstrated after IL-4 and insulin stimulation of the Hep3B hepatoma cells. Both insulin and interleukin 4 stimulated tyrosine phosphorylation and the enzyme activity of Erk1 kinase. Our results indicate that interleukin 4 and insulin might modulate hepatic cell growth and differentiation through many different or common pathways for the activation of JAK kinases and the usage of IRS-1 as a docking protein. The binding of IRS-1 with Grb2 after IL-4 as well as insulin stimulation may lead to MAP kinase activation, probably through the Grb2/sos/p21ras pathway.

Shock as a complication of cancer

Shock is a syndrome in which multiple etiologies converge on a pathway of response which, although preservative and compensatory early on, rapidly becomes irreversible and fatal. The mechanisms of this response are under intense investigation, though little therapeutic improvement has accompanied our understanding. The patient with malignancy is at risk for developing shock both as a result of his disease and therapy for his disease, yet he is by no means alone in his vulnerability. Technologic advances may still bring more effective support to the shock patient, while immunologic advances may ultimately provide support to the shock patient, while immunologic advances may ultimately provide answers and cure.

Direct visualization of the phosphorylated epidermal growth factor receptor during its internalization in A-431 cells

Epidermal growth factor (EGF) rapidly stimulates receptor autophosphorylation in A-431 cells. After 1 min the phosphorylated receptor can be identified at the plasma membrane using an anti-phosphotyrosine antibody. With further incubation at 37 degrees C, approximately 50% of the phosphorylated EGF receptor was internalized (t1/2 = 5 min) and associated with the tubulovesicular system and later with multivesicular bodies, but not the nucleus. During this period, there was no change in the extent or sites of phosphorylation. At all times the phosphotyrosine remained on the cytoplasmic side of the membrane, opposite to the EGF ligand identified by anti-EGF antibody. These data indicate that (a) the tyrosine-phosphorylated EGF receptor is internalized in its activated form providing a mechanism for translocation of the receptor kinase to substrates in the cell interior; (b) the internalized receptor remains intact for at least 60 min, does not associate with the nucleus, and does not generate any tyrosine-phosphorylated fragments; and (c) tyrosine phosphorylation alone is not the signal for receptor internalization.

Insertion of difficult nasogastric tubes through a nasoesophageally placed endotracheal tube

A technique is described to facilitate the insertion of NG tubes with the aid of nasoesophageal insertion of an endotracheal tube. This technique is particularly useful in comatose and anesthetized patients. The equipment utilized is easily assembled and readily available. We have found this method to be easier and more successful than those previously described.

Hemodynamic oxygen transport and 2,3-diphosphoglycerate changes after transfusion of patients in acute respiratory failure

The goals of management of patients with respiratory failure include improving arterial oxygenation with PEEP and red cell transfusion to maintain oxygen carrying capacity, both of which contribute to improving tissue oxygen delivery. However, standard CPD-stored blood is rapidly depleted of 2,3 diphosphoglycerate (2,3 DPG) and ATP, with resultant inadequacy of the red cell oxygen transport function. In 15 patients requiring mechanical ventilation with PEEP whose initial Hct less than or equal to 35%, we studied the effect of transfusion of 7 ml/kg of CPD-stored packed red blood cells on hemodynamic and oxygen delivery variables, pulmonary venous admixture (QA/QT), and erythrocytic P50, 2,3 DPG and ATP concentrations. Hemodynamics were not significantly altered by transfusion. 2,3 DPG decreased significantly from 14.5 +/- 1.1 to 13.1 +/- 1.5 mcmol/g Hb (mean +/- SD, p less than 0.05). There was no significant change in P50 or ATP. QA/QT rose significantly, from 20.1 +/- 7.8 to 28.9 +/- 12.3% (mean +/- SD, p less than 0.02). In our patients, an increase in arterial oxygen content obtained by transfusion was not followed by any associated decrease in cardiac work, as implied by solution of equations for oxygen delivery and oxygen consumption. The rise in QA/QT is undesirable in patients requiring PEEP, since it complicates management of their mechanical ventilatory support.

Dopamine administration in oliguria and oliguric renal failure

Oliguric renal failure significanlty worsens the prognosis of many critical illnesses, particularly in patients with respiratory failure. In 52 patients, a continuous infusion of dopamine, 1.5-2.5 micrograms/kg . min, was administered when creatine clearance (Ccr) fell below 40 ml/min and urinary output was less than 1 ml/kg . h despite normal intravascular volume. In 18 patients, a continuous infusion of furosemide (3-5 mg/kg . day) was also administered. Daily, two 3-h collections of urine and blood specimens were obtained to determine Ccr, osmolar clearance (Cosm), free water clearance (CH2O) and excreted fraction of filtered sodium (FENa); one collection was made during dopamine infusion and one while the infusion was suspended. Cardiac output and pulmonary venous admixture were also measured. The authors obtained 199 urine collections in 52 patients; considering the aggregate patient pouplation, urinary output increased by 42.3% (30.2 +/- 3.45 (SEM) ml/h), on dopamine infusion. Cosm, FENa, and Ccr were also higher on dopamine. CH2O and hemodynamic variables were not altered by dopamine infusion. When patients were startified on the basis of mechanical ventilatory support, Ccr and furosemide administration, dopamine infusion essentially caused the same changes in the variables studied as described for the aggregate patient population. Diuresis and sodium excretion increased significantly on dopamine even in those patients receiving furosemide infusion. The authors conclude that fluid and osmolar load can be eliminated more effectively in critically ill patients with continuous infusion of 1.5-2.5 micrograms/kg . min of dopamine.

Clinical experience with high frequency jet ventilation

High frequency jet ventilation (HFJV) has been used in recent years in some forms of respiratory failure, where the presence of barotrauma limited the application of high peak inspiratory pressure. In the present report, the authors describe the clinical experience with 17 patients, who could not be supported with conventional mechanical support and were placed on HFJV. Rates of 100 breath/min, inspiratory/expiratory ratio of 1:2 and cannula size of 1.06--1.62 mm (18--14) gauge were used. Driving pressure required to maintain a PaCO2 of 40--45 torr was 14--45 psig; however, except in 2 patients who developed hemorrhagic tracheitis with subtotal obstruction of both mainstem bronchi, a driving pressure higher than 27 psig was never required, even when PEEP up to 32 cm H2O was used. Of 17 patients treated, 8 survived. In all cases, alveolar ventilation could be maintained within the desired range with high frequency ventilation, even in those patients who eventually died; mechanical support never provided better oxygenation or alveolar ventilation than high frequency ventilation. Hemodynamic function was essentially unchanged with high frequency ventilation; indeed, in three cases, inotropic support with dopamine could be discontinued after initiation of high frequency ventilation.

Technical aspects and clinical implications of high frequency jet ventilation with a solenoid valve

High frequency jet ventilation (HFJV) is an incompletely studied technique of mechanical respiratory support. The authors have built a ventilator based on a solenoid valve, that allows independent selection of respiratory rate and inspiratory/expiratory ratio. The ventilator can be synchronized to the heart rate. Humidification is provided by warm saline dripped in front of the injector nozzle, so that the jet stream itself acts as a nebulizer. Tube diameter, length, and deformability are fundamental determinants of inspiratory flow rate and wave form. Cannula kinking and inadequate humidification were the most significant sources of complications.

Pulmonary venous admixture during mechanical ventilation with varying FIO2 and PEEP

Many authors have indicated that high FIO2 (0.75-1.0) ventilation may increase pulmonary venous admixture. Reabsorption atelectasis is supposedly responsible for this adverse effect. The authors attempted to determine if increasing PEEP during high FIO2 ventilation could eliminate the detrimental influence of the latter. In 17 patients in respiratory failure, hemodynamic and respiratory variables were measured during ventilation with FIO2 0.50, 0.75, and 1.0 and PEEP varying from -3 to +5 cm H2O from baseline. Before exposure to FIO2 > 0.75, addition of PEEP resulted in a decrease of Qs/Qt from a mean of 26.6-21.9%. After exposure to FIO2 0.75-1.0, Qs/Qt remained at levels not different from baseline, even when PEEP 8 cm H2O above baseline was added. The authors conclude that ventilation with high FIO2 is not useful in determining Qs/Qt, and may prevent the improvement in pulmonary venous admixture associated with PEEP therapy.

Evaluation of an "in vivo" PaO2 and PaCO2 monitor in the management of respiratory failure

A commercially available gas-chromatograph (Sentorr Gas Analyzer, Ohio Medical Products, Madison, WI) was tested, featuring continuous measurement of in vivo PaO2 and PaCO2 by means of a thin, heparin-coated catheter, inserted through an indwelling arterial line. Gas tensions are displayed every 4 min. The probes had a tendency to break rather easily, and a considerable proportion of them was faulty. We measured 105 paired determinations of blood gases obtained from patients in respiratory failure requiring mechanical ventilation with a Corning IL 175 Analyzer and displayed by the Sentorr Gas Analyzer. A high correlation (p < 0.01) existed between the two sets of values, but an estimated error of 10-20% was found in the Sentorr data. After modifications of the respirator, changes of displayed values were already notable after 4 min and 90% completed by 8-12 min. The use of this device enabled us to considerably accelerate decision-making in the management of respiratory failure. Although techology still necessitates improvements, before widespread use of in vivo monitoring of PaO2 and PaCO2 is advisable, the concept has significant clinical potential and may represent a major advance in the management of respiratory failure.

Calcium chloride administration in normocalcemic critically ill patients

Ten normocalcemic critically ill patients who had experienced a decrease in cardiac index greater than or equal to 0.5 liter/min/m2 after incremental changes of PEEP received 7 mg/kg of CaCl2 as a slow iv bolus, followed by an infusion of 20 mg/kg CaCl2 over 60 min. Hemodynamic pressures and flow, oxygen uptake and transport, and blood chemistry variables were determined over a 120-min period. The results indicated that: (1) hemodynamic variables were not affected except for left ventricular stroke work index and mean blood pressure, which increased slightly; (2) both serum calcium and ionized calcium concentrations increased significantly, sometimes to dangerous levels; (3) colloid osmotic pressure and hemoglobin levels decreased slightly but consistently. In conclusion, CaCl2 administration failed to improve hemodynamic function depressed by PEEP. If CaCl2 can play a relevant role in the management of cardiovascular depression, further identification of appropriate doses and patients is necessary.

Prazosin in acute anthracyclene cardiomyopathy

A 32-year-old woman with a 14-month history of acute lymphoblastic leukemia received 300 mg/sq m of doxorubicin. Shortly after the last course of therapy, congestive failure developed that was attributed to anthracyclene cardiomyopathy. Three weeks later, an acute septic episode was complicated by hypotension and low cardiac output. Adequate blood pressure and cardiac output were restored with a combined intravenous infusion of dopamine hydrochloride and nitroglycerine. Within 24 hours, oral therapy with prazosin and digitalis was initiated, and two days later, the intravenous infusions could be discontinued. Acute anthracyclene cardiomyopathy can be successfully treated with a combination of oral inotropic and vasodilating agents.

Unexpected giant "V" waves during pulmonary artery catheterization

Two cases of catheterization of the pulmonary artery, in which the hemodynamic findings were very different from the initial clinical diagnosis, are presented. The importance of verifying the adequate position and motion of the pulomonary artery catheters with two consecutive chest x-rays is discussed. In particular, attention is brought to the possible misinterpretation that occurs in patients with very elevated pulmonary artery mean pressure.

Rapid volume expansion in patients with interstitial lung diseases

Rapid administration of intravascular volume expanders is often necessary during anesthesia. Significant controversy still exists on the relative values of different volume expanders. Fifteen hypoxemic patients (Pao2 less than 70 torr on room air) were studied preoperatively. They were randomized into three groups. One group received 1.5 ml/kg of 25% salt-poor human albumin, a second group, 7 ml/kg of fresh frozen plasma; a third group, 7 ml/kg of 0.9% NaCl in water (normal saline). The infusions were given intravenously and completed in 20 minutes. Changes in hemodynamic pressures and flows, blood chemistries, and oxygen uptake and transport variables were studied. It was concluded that fresh frozen plasma afforded the greatest increase in cardiac output and oxygen availability with the least increase in left ventricular stroke work. Colloid osmotic pressure was more significantly increased by fresh frozen plasma than by salt-poor human albumin. Normal saline caused both a decrease in oxygen availability and colloid osmotic pressure. Pulmonary venous admixture increased to some extent in all patients receiving fresh frozen plasma or normal saline. In three patients, this increase was very marked and accompanied by severe arterial hypoxemia.

Unusual complications during pulmonary artery catheterization

Two unusual complications, encountered during pulmonary artery catheterization, are described. In both cases the catheter had been introduced percutaneously with the Seldinger technique. Inadvertent entry of the right pleural space occured in one case in which the catheter had been inserted into the internal jugular vein through a low cervical approach. The second complication was separation of the shaft of the introducer from the hub, with consequent risk of embolization. Possible means of preventing and treating these complications are discussed.

Long-term infusion of sodium thiopental: hemodynamic and respiratory effects

To establish the possible advantages of ultrashort acting barbiturates administered in continuous infusion as the only sedative agent for mechanically ventilated patients, sodium thiopental was given to 30 subjects for periods ranging from 2--14 days. Plasma levels were maintained at approximately 15 microgram/ml, using both laboratory determinations and clinical judgment. This technique proved effective for patients requiring either controlled ventilation or intermittent mandatory ventilation. None of the hemodynamic and respiratory variables studied was significantly altered during the infusion, with the exception of decreased heart rates. In view of these results, the technique is considered both expedient and safe for prolonged sedation of patients requiring ventilatory support.

Adverse effects of calcium administration. Report of two cases

Calcium chloride, 7 mg/kg, and calcium gluconate, 20 mg/kg, were administered to patients with low or low-normal levels of serum ionized calcium. Both patients had low blood pressure and cardiac index, and did not respond to digitalis, volume expansion, and beta-adrenergic stimulation with dopamine. Administration of calcium rapid increase of serum ionized calcium levels, decrease of serum potassium levels, and development of severe cardiac arrhythmias. Atrioventricular dissociation and further fall of cardiac index and blood pressure were common features of both cases. Administration of exogenous calcium can cause severe complications, even when theoretically indicated.