What rate of infusion of intravenous nutrition solution is required to stimulate uptake of amino acids by peripheral tissues in depleted patients?

We examined the effect of varying the quantities (0, 0.1, 0.2, 0.3, and 0.4 gN.kg-1.[day]-1) of nitrogen input on N balance, 3-methylhistidine (3MH) excretion, plasma amino acid concentration and the net flux of amino acids across the leg in depleted patients requiring parenteral nutrition. The calorie-to-nitrogen ratio was 140 to 1 (kcal:1 gN) and consequently the patients received varying amounts of calories (8, 14, 28, 42, and 56 kcal.kg-1.[day]-10. There was negative nitrogen balance and net loss of amino acids from the limb during fasting. An infusion of 0.2 gN.kg-1.[day]-1 of IVN reversed the net catabolic process and resulted in equilibrium of peripheral total amino acid flux and of tyrosine flux without a decrease in 3MH excretion. Net uptake of total amino acids and tyrosine in peripheral tissues was achieved with 0.4 gN.kg-1.[day]-1 and 56 kcal.kg-1.[day]-1. This was associated with a fivefold increase in 3MH excretion (p less than 0.01), indicating that net anabolism occurred with increased protein turnover. Fifty per cent of the amino acids taken up by peripheral tissues during infusions of 0.4 gN.kg-1.[day]-1 was due to the uptake of glutamate (Glu) and 20% was due to the uptake of branched chain amino acids (BCAA). Plasma Glu concentration, [Glu], did not increase with increasing IVN infusion, but BCAA concentrations did. Although the mean plasma [Glu] did not change with IVN infusion, there was an independent effect of plasma [Glu] (p less than 0.0001) and of N input (p less than 0.0001) on Glu flux, indicating that even at high infusion rates the maximal capacity of peripheral tissues to take up Glu had not been reached.

Hepatic microvascular changes associated with development of liver fibrosis and cirrhosis

Quantitative data defining basic microvascular parameters are needed for better understanding of the relationship between liver blood flow and function under normal and pathological conditions. The present study was undertaken to quantitate the following microvascular parameters: flow velocities in sinusoids and terminal hepatic venules; the range of sizes of terminal hepatic vessels; and acinar sizes in both normal rat livers and during the development of liver cirrhosis. Fibrosis and cirrhosis were induced by either weekly administration of carbon tetrachloride (CCl4) or by choline-deficient diet. Microcirculation was observed using intravital epifluorescent video microscopy and recorded on a videotape for subsequent analysis. It was found that even early stages of liver disease, when only mild hepatic fibrosis was present, are associated with profound changes in the hepatic microvasculature. These changes include the appearance of highly fluorescent cells in the liver parenchyma (mainly in the areas where collagen is being deposited), a marked dilatation of the terminal hepatic venules, an increase in hepatic venous outflow, and appearance of sinusoids with very high flow velocities. As fibrosis progresses to cirrhosis, the proportion of these "fast sinusoids" increases from 7% in fibrotic livers to 33% in cirrhotic livers. These results demonstrate the presence of functional intrahepatic shunts in cirrhotic livers and support the hypothesis that hyperdynamic splanchnic circulation may be an important factor in the etiology of portal hypertension in liver disease.

Anaphylaxis following administration of papaveretum. Case report: Implication of IgE antibodies that react with morphine and codeine, and identification of an allergenic determinant

IgE antibodies that reacted with morphine and codeine were detected in the serum of a subject who experienced a life-threatening anaphylactic reaction following the administration of Omnopon-Scopolamine (papaveretum-hyoscine). Hapten inhibition studies with morphine and a number of structurally-related analogues revealed that morphine and codeine were the most potent inhibitors of IgE binding to a morphine-solid phase. Nalorphine, meperidine, and methadone were also good inhibitors of IgE binding, but naltrexone, buprenorphine, and fentanyl proved to be poor inhibitors. From a detailed examination of structure-activity relationships, the authors conclude that the important structural features of the morphine allergenic (that is, IgE binding) determinant comprises the cyclohexenyl ring with a hydroxyl group at C-6 and, most important of all, a methyl substituent attached to the N atom. The authors' findings suggest that morphine analogues administered to such a patient may provoke clinical anaphylaxis. Hyoscine reacted weakly with IgE antibodies in the subject's serum, but this was thought to be due to weak cross-reaction between this compound and morphine.

External chest compression in acute asthma: a preliminary study

The technique of external chest compression to assist expiration has been used in asthmatic patients for some years, but it has not been described in detail in the medical literature. We describe a method for assisted expiration and its apparent value in the emergency treatment of asthma. The technique requires further evaluation to determine its role in the resuscitation of asthmatics.

Urban envenomation

Over a 12-year period, 61 patients were admitted to a metropolitan hospital on 67 occasions with envenomation from snakes, spiders, ticks or bees. We describe the epidemiology of the bites and the patient's response to treatment. First aid was used in only 50% of patients with potentially-lethal bites. All patients who developed severe envenomation showed symptoms within 30 minutes, and all patients survived.

Constancy of air-oxygen mixtures in intensive care

The performance of ten high-flow Bird blenders (3M Company) was assessed to ascertain the stability of the oxygen delivery both over time and within a single respiratory cycle. Blended oxygen concentrations were assessed for both continuous low flow and for intermittent flow with variable tidal volumes as is seen with mechanical ventilation. Studies were repeated after the addition of a high flow bleed from the blender via a T-piece. We observed clinically significant variations in the oxygen concentrations delivered by several blenders when the relationship between air and oxygen supply pressures varied. This variability was greatest when the air and oxygen pressures were nearly equal. When the line pressures were stable, mixed oxygen concentrations were constant but variations in oxygen delivery were found within individual breath cycles. This could be explained by postulating that at the initiation of flow from the blender a small pocket of unblended gas (pure air or pure oxygen) was issued by the blender before the balancing mechanism stabilised to deliver the desired oxygen concentration. This variability of oxygen delivery may have considerable impact on the measurement of oxygen consumption using the open circuit technique. The addition of a high flow bleed completely ablated this blender-derived variation in oxygen delivery.

The optimization of renal function in acute illness

The development of acute renal failure increases the morbidity, the mortality and the duration of hospital stay of all patients who are treated in intensive-care units. Consequently, the prevention of renal failure, and especially that of oliguric acute renal failure, has a high priority in the management of patients who are seriously-ill. The identification of risk factors, the pretreatment of patients who are in high-risk categories and the maintenance of adequate hydration, oxygenation, cardiac output and renal blood flow are the first-line priorities in management. The use of loop diuretic agents, mannitol and dopamine, separately or in combination, probably are effective prophylactic measures. They also may have therapeutic benefit in the maintenance of a non-oliguric state in the presence of acute renal failure, although there is less scientific support for this role. Such manoeuvres are worthy of trial before an oliguric state is accepted. They are more likely to be efficacious if they are instituted early.

Acute anaphylactic reactions

Anaphylactic shock may be provoked by a diverse group of substances and stimuli, which range from large molecular weight proteins and small drug molecules to some colloids, emulsions and even exercise. The underlying mechanism may be immunological or non-immunological but, regardless of the mechanism, the physiological effects and the observable symptoms of anaphylaxis are due to the release of potent pharmacologically-active mediators, including histamine. Although a number of predisposing factors are recognized, the appearance of most of the reactions cannot be predicted. Reactions occur suddenly and dramatically and progress rapidly. Cardiovascular collapse is the most common life-threatening clinical feature, while bronchospasm is the most difficult to treat. The primary aim of treatment should be to treat the underlying cause and to improve cellular oxygenation. The pharmacological agent of choice for treatment is adrenaline. It is direct-acting and is effective for both bronchospasm and cardiovascular collapse. It is imperative that the provoking substance or stimulus be identified in patients and there is no substitute for a carefully-gathered and detailed case history in the diagnosis of anaphylaxis. Patients should be issued with some form of warning identification together with written details concerning their reaction.

Profound reversible myocardial depression after anaphylaxis

Profound myocardial depression developed in 2 patients after severe anaphylactic reactions following the induction of anaesthesia in 1 case and a bee-sting in the other. Neither patient had pre-existent cardiac disease. In both patients haemodynamic assessment, radionuclide ventriculography, and two-dimensional echocardiography confirmed the clinical impression of profound systolic myocardial dysfunction. Haemodynamic stability was attained by intra-aortic balloon counterpulsation, which was probably life-saving in both cases. Cardiac function improved rapidly although some contractile depression persisted for several days. At follow-up both patients had normal cardiac function with no evidence of underlying heart disease.

Can clinical anaphylaxis to anaesthetic drugs be predicted from allergic history?

The incidence of a history of allergy, atopy or asthma is greater in patients who undergo life-threatening clinical anaphylaxis to anaesthetic drugs. However, because the incidence is low, the presence of such a history is not a reliable predictor of the likelihood of a reaction in an individual patient, and does not indicate that the patient should be investigated or pretreated, or that the selection of drug(s) be altered to reduce the likelihood of a reaction.

Nonparenchymal liver cells and granulomas during lamprey biliary atresia

Transmission (thin sections and freeze-fracture replicas) and scanning electron microscopy were used to describe the nonparenchymal liver cells during the seven (1-7) stages of metamorphosis in the sea lamprey, Petromyzon marinus L., when bile ducts and canaliculi degenerate. The biliary atresia is accompanied by an increased diameter of fenestrae in the endothelium, an active phagocytosis by Kupffer cells in the sinusoids, and large lipid inclusions in perisinusoidal lipocytes (fat-storing or Ito cells). Plasma-like cells and foci of nonparenchymal cells (granulomas) are present in the liver interstitium during at least four stages of metamorphosis. The fenestrae in the sinusoidal wall are wider (up to 2.8-micron diameter) than normally reported for vertebrate livers but are likely a reflection of the morphogenetic and physiological events and consequences of the biliary atresia. Kupffer cells are involved in an extensive erythrophagocytosis, the storage of iron, and perhaps the incorporation of cellular components from hepatocytes. Lipocytes are the vitamin A-storing cells of the transforming liver and may be responsible for some perisinusoidal fibrosis. Granulomas are present during stages 3-6 and are focal areas where mononuclear leukocytes (lymphocytes and plasmalike cells), macrophages, and neutrophils have infiltrated the hepatic parenchyma. The function of the granulomas is not known; but their presence may be related to the porous nature of the sinusoidal wall, the tissue degeneration, and/or the physiological change (e.g., bile stasis) during biliary atresia.

Drugs as allergens: the molecular basis of IgE binding to thiopentone

Using an immunoassay developed for the detection of thiopentone-reactive IgE antibodies, the combining site specificities of such antibodies found in sera of patients who experienced life-threatening anaphylactic reactions to the drug were studied. The antibody combining sites from one patient were complementary to the region of the thiopentone molecule containing a thio group at position 2 of the barbiturate ring. The allergenic determinant recognized by IgE antibodies from another patient encompassed a secondary pentyl group and an ethyl group attached to position 5 on the other side of the barbiturate ring. Thus, it is already clear that there is more than one allergenic determinant on the thiopentone molecule with the capacity to provoke IgE formation and drug-induced allergic reactions.

Detection of thiopentone-reactive IgE antibodies following anaphylactoid reactions during anaesthesia

A radioimmunoassay was developed to detect IgE antibodies to the anaesthetic induction agent thiopentone. Significant levels of thiopentone-reactive IgE antibodies were found in the sera of two patients who had experienced life-threatening anaphylactoid reactions following administration of the drug. Inhibition experiments revealed that cross-reactivity occurs between the drug-reactive IgE antibodies and four barbiturate analogues pentobarbitone, phenobarbitone, barbitone and methohexital. The assay should supplement skin testing for the detection of patients with potentially lethal sensitivity to thiopentone.

Antigenic similarity between the protein neurotoxin alpha-bungarotoxin and neuromuscular blocking drugs

The snake neurotoxins alpha-bungarotoxin (alpha-BGT) and beta-bungarotoxin (beta-BGT) which act at the neuromuscular junction, were found to bind to IgE antibodies directed against neuromuscular blocking (NMB) drugs in the sera of two patients who had experienced lifethreatening anaphylactic reactions to succinylcholine. alpha-BGT inhibited IgE-binding to a choline-Sepharose solid support in one patient better than the NMB drug alcuronium, choline, triethylcholine and beta-BGT. IC50s for alpha-BGT and succinylcholine were 16 and 10 nmol respectively for one patient and 34 and 6.0 nmol for the other. Recognition of the NMB drugs and alpha-BGT by the same antibody is the first demonstration of an antigenic similarity between these drugs and the protein toxin.

Hepatic transport of fluorescent molecules: in vivo studies using intravital TV microscopy

Experiments were undertaken to evaluate the role of intravital epifluorescent TV microscopy in the study of the hepatic transport of sodium fluorescein and fluorescently labeled sodium glycocholate in rats and hamsters. It was found that the apparent sinusoid to canaliculus transport time for fluorescently labeled sodium glycocholate was only half of that for sodium fluorescein, 0.50 and 0.92 sec, respectively. The sinusoid to bile transport time was 35 sec for fluorescently labeled sodium glycocholate and 90 sec for sodium fluorescein. There were also marked differences in zonal clearance of these two substances. Sodium fluorescein was removed from Zone 1 much faster than from Zone 3, while fluorescently labeled sodium glycocholate was cleared at the same rate by hepatocytes in all three acinar zones. This study provides direct evidence that there are zonal differences in hepatic transport rates for certain compounds. It also demonstrates that epifluorescent TV microscopy has the potential to provide quantitative data on the transport rates of bile acids and other molecules into, through and out of the liver.

Human IgA as a heterovalent ligand: switching from the asialoglycoprotein receptor to secretory component during transport across the rat hepatocyte

Asialoglycoproteins are taken up by the rat liver for degradation; rat polymeric IgA is taken up via a separate receptor, secretory component (SC), for quantitative delivery to bile. There is negligible uptake of these ligands by the converse receptor, and only a low level of missorting of ligands to opposite destinations. The two pathways are not cross-inhibitable and operate independently (Schiff, J.M., M. M. Fisher, and B. J. Underdown, 1984, J. Cell Biol., 98:79-89). We report here that when human IgA is presented as a ligand in the rat, it is processed using elements of both pathways. To study this in detail, different IgA fractions were prepared using two radiolabeling methods that provide separate probes for degradation or re-secretion. Behavior of intravenously injected human polymeric IgA in the rat depended on its binding properties. If deprived of SC binding activity by affinity adsorption or by reduction and alkylation, greater than 80% of human IgA was degraded in hepatic lysosomes; radioactive catabolites were released into bile by a leupeptin-inhibitable process. If prevented from binding to the asialoglycoprotein receptor by competition or by treatment with galactose oxidase, human IgA was cleared and transported to bile directly via SC, but its uptake was about fivefold slower than rat IgA. Untreated human IgA was taken up rapidly by the asialoglycoprotein receptor, but depended on SC binding to get to bile: the proportion secreted correlated 1:1 with SC binding activity determined in vitro, and the IgA was released into bile with SC still attached. These results demonstrate that human IgA is normally heterovalent: it is first captured from blood by the asialoglycoprotein receptor, but escapes the usual fate of asialoglycoproteins by switching to SC during transport. Since the biliary transit times of native human and rat IgA are the same, it is probable that the receptor switching event occurs en route. This implies that the two receptors briefly share a common intracellular compartment.

Unexplained acute membrane pulmonary oedema related to anaesthesia

Five patients developed severe pulmonary oedema in relationship to elective anaesthesia and surgery. The oedema was due to increased capillary permeability in four patients and probably due to increased capillary permeability in the other. No cause could be found in any patient.

Convoluted bile ducts in the liver of the larval lamprey, Petromyzon marinus L

The three-dimensional structure of the bile ducts and their relationship to the blood vessels were studied in the larval lamprey by scanning electron microscopy of the intact tissue and of biliary and vascular casts. The intrahepatic gall bladder is situated in the cephalic portion of the liver and a cystic duct is connected to a straight intrahepatic common bile duct, which extends to the extrahepatic bile duct at the caudal end of the liver. Several smaller intrahepatic common bile ducts are connected directly to the intrahepatic common bile duct, are convoluted or serpiginous and are surrounded intimately by sinusoids. This arrangement enables the bile ducts to have increased surface area exposed to blood vessels. The functional significance of this arrangement is discussed with respect to the modification of bile through the transport of solutes and the similarity of this bilio-vascular relationship to the peribiliary vascular plexus of the mammalian liver.

Clinical observations on the pathophysiology and treatment of anaphylactic cardiovascular collapse

Observations in 205 patients with cardiovascular manifestations of anaphylactic shock confirmed the belief that adrenaline is the drug of first choice in management and that colloid solutions are preferable to crystalloid solutions in volume replacement. Arrhythmias and elevated filling pressures are more common in patients with cardiac disease but the sympathetic response appears to override the cardiac effects of histamine in healthy patients.