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.