Secretory component as the mucosal transport receptor: separation of physicochemically analogous human IgA fractions with different receptor-binding capacities

This paper describes the separation and characterization of several IgA fractions from the same human monoclonal source, based on their ability to bind secretory component (SC). The study was undertaken to elucidate features of the immunoglobulin-binding site for SC, and to examine the dependence of mucosal transport on IgA-SC interaction. Enrichment or depletion of SC-binding activity was accomplished on an affinity adsorbant made with SC from human colostral whey. The affinity-purified human IgA fractions contained IgA polymers and were 77% active in rebinding to the adsorbant; this activity was diminished significantly by direct radioiodination. The non-adherent IgA fractions contained both polymer and monomer, and were only 8% active in rebinding to the adsorbant. When the polymer and monomer components were separated from each other, the non-adherent polymer was found to resemble the affinity-purified fraction by all criteria examined including J-chain content, except that the SC-binding capacity was greater than five-fold lower. These findings have two implications for the SC-binding site on human IgA: first, the presence of J-chain is insufficient to bestow IgA with SC-binding activity; second, a critical tyrosine participates in maintaining the SC-binding region, possibly on the IgA heavy chain. The relationship between SC binding and mucosal transport was tested in the rat hepatobiliary model. All radiolabeled human IgA fractions were captured rapidly from blood by the rat liver, but only the SC-binding fractions underwent substantial intact transport to bile (greater than 70% of the injected dose). Even though a nominal proportion of the SC-non-adherent IgA appeared in bile (4-15% of the dose), most IgA in these fractions was rapidly degraded within the liver. Thus, only a small amount of monomeric and polymeric IgA can use alternative receptors to get to bile by diversion from the degradative pathway. Polymeric IgA can undergo efficient transport across the cell, strictly conditional on a high binding capacity for SC. This demonstrates that membrane SC is the receptor conferring specificity on the mucosal-transport pathway.

Periductal fibrosis and lipocytes (fat-storing cells or Ito cells) during biliary atresia in the lamprey

Transmission and scanning electron microscopy were utilized to follow the degeneration of bile ducts of lampreys (Petromyzon marinus L.) during metamorphosis. The convoluted bile ducts of larval lampreys are surrounded by rich sinusoids, but this intimate biliovascular relationship is lost during metamorphosis because the bile duct degeneration is accompanied by the development of thick periductal fibrosis. Lipocytes, which are present not only in the parenchyma but also in the interstitial tissue of the liver, increase in number in the periductal fibrous tissue, and their processes are directly opposed to collagen fibrils. Fibrillar materials in the dilated cisternae of the rough endoplasmic reticulum and the nuclear envelope of lipocytes are believed to be excreted by exocytosis in a manner similar to such excretion by fibroblasts. The findings suggest that lipocytes are responsible for the periductal fibrosis during biliary atresia in lampreys. This animal might prove to be an interesting model in which to study the biology and fibrogenic potential of lipocytes.

Cross-reactivity of metocurine, atracurium, vecuronium and fazadinium with IgE antibodies from patients unexposed to these drugs but allergic to other myoneural blocking drugs

An inhibition assay was used to determine quantitatively the allergenic cross-reactivity of some myoneural blocking drugs not yet released for use in Australia, in the sera of patients who had experienced anaphylactic reactions to neuromuscular blocking drugs. Two of the compounds, metocurine and atracurium were highly cross-reactive with the currently used myoneural blockers; fazadinium was weakly cross-reactive and vecuronium intermediate in potency between these two extremes. From these results, we predict that anaphylactic reactions to these compounds, and particularly to metocurine and atracurium, will occur in some patients allergic to the currently used neuromuscular blocking agents.

Lymph cysts or lymphocoele: a case report

A patient with a lymph cyst of the thigh following sulfuric acid burns of both feet is presented. It was diagnosed by percutaneous lymphangiography with Ethiodal. Omentopexy was performed with success. A complication of hernia of small intestine into the thigh was corrected by herniorraphy. Omentopexy is an excellent modality to improve lymph flow. Awareness of hernia post operatively may limit its use.

Inhibition of histamine-N-methyltransferase activity by neuromuscular blocking drugs

On the basis of previous findings that histamine-N-methyltransferase (HMT) activity can be significantly enhanced or inhibited by a number of analogues of histamine and drugs containing dialkylaminoalkyl moieties, we investigated whether the neuromuscular blocking drugs alcuronium, d-tubocurarine, decamethonium, succinylcholine, gallamine and pancuronium each of which contain quaternary ammonium groups, influence the activity of HMT. Our findings showed that all six drugs significantly inhibited HMT activity in the concentration range 10(-7)-10(-3) M with alcuronium being the most potent inhibitor (I.D.50 = 2 X 10(-6) M). Activities at these concentrations reveals that alcuronium, pancuronium, d-tubocurarine and gallamine are more potent inhibitors than two of the most potent histamine analogue inhibitors, N tau-methylhistamine and 2-methylhistamine. Alcuronium proved to be of similar potency to the dimaprit analogue, SKF 91488 regarded as one of the most potent HMT inhibitors known. The structurally similar and chemically least complex straight chain neuromuscular blocking compounds, succinylcholine and decamethonium proved to be the least potent inhibitors.

Preventing hepatitis B in health care workers

Exposure to hepatitis B virus (HBV) infection is a potentially serious occupational hazard for health care workers. Data indicate an increased risk of HBV infection in health care workers. This risk appears to be related to the frequency of contact with patients' blood and exposure to high risk patient populations. Strategies available for preventing HBV infection in the health care setting include HBV vaccine, which is the most efficacious and practical strategy. In view of the potential consequences of HBV infection, health care employers have a responsibility to provide education, serological testing and vaccination. Health care workers have a responsibility to use these programs, and to assess their own risk of infection.

Disulfiram-induced hepatitis. Report of two cases and review of the literature

Two cases of disulfiram-induced hepatitis are presented. Both cases had prompt recurrence of abnormal liver function tests after rechallenge with small doses of the drug. All cases of disulfiram-induced hepatotoxicity reported in the English literature are reviewed.

A role for the spleen in the appearance of IgM in the bile of rats injected intravenously with horse erythrocytes

The i.v. injection of the particulate antigens horse red blood cells (HRBC) and Salmonella enteritidis into rats results in the appearance of high levels of IgM agglutinating antibody in the serum and bile. This is in contrast to the appearance of specific IgA antibodies in bile after the injection of antigen into the Peyer's patches. At the height of the response, a fivefold to 10-fold increase in total IgM was found in bile, whereas there was no increase in IgA or in total protein levels. The biliary IgM was not associated with secretory component. Studies aimed at revealing the source of the IgM showed that neither immunized nor nonimmunized rats were able to transport 131I-rat IgM, but both groups were equally efficient at transporting 125I-rat IgA. Furthermore, specific anti-HRBC antibody could not be detected in the bile of rats that were injected with a high titer serum, indicating that blood is unlikely to be the source. Splenectomy of rats at the time of the injection of antigen, at 3 days after immunization had abrogated the biliary response, and at 5 days resulted in rapid decline in existing specific antibody level. Involvement of the spleen was additionally implicated when it was shown that injection of animals with immune spleen cells gave rise to specific antibodies in serum and bile. On the basis of these experiments, it is proposed that antigen entering the blood stream can stimulate a population of cells in the spleen that emigrates to the liver, where the cells localize and secrete IgM into bile.

A role for the spleen in the appearance of IgM in the bile of rats injected intravenously with horse erythrocytes

The i.v. injection of the particulate antigens horse red blood cells (HRBC) and Salmonella enteritidis into rats results in the appearance of high levels of IgM agglutinating antibody in the serum and bile. This is in contrast to the appearance of specific IgA antibodies in bile after the injection of antigen into the Peyer's patches. At the height of the response, a fivefold to 10-fold increase in total IgM was found in bile, whereas there was no increase in IgA or in total protein levels. The biliary IgM was not associated with secretory component. Studies aimed at revealing the source of the IgM showed that neither immunized nor nonimmunized rats were able to transport 131I-rat IgM, but both groups were equally efficient at transporting 125I-rat IgA. Furthermore, specific anti-HRBC antibody could not be detected in the bile of rats that were injected with a high titer serum, indicating that blood is unlikely to be the source. Splenectomy of rats at the time of the injection of antigen, at 3 days after immunization had abrogated the biliary response, and at 5 days resulted in rapid decline in existing specific antibody level. Involvement of the spleen was additionally implicated when it was shown that injection of animals with immune spleen cells gave rise to specific antibodies in serum and bile. On the basis of these experiments, it is proposed that antigen entering the blood stream can stimulate a population of cells in the spleen that emigrates to the liver, where the cells localize and secrete IgM into bile.

Three-dimensional observations of the hepatic arterial terminations in rat, hamster and human liver by scanning electron microscopy of microvascular casts

The arterial terminations were studied by scanning electron microscopy of microvascular casts in rat, hamster and human livers. Important species differences were observed. In the rat, frequent anastomoses between the terminal hepatic arterioles and portal venules were observed, whereas a few arterioles terminated directly into sinusoids. On the contrary, no arterioportal venous anastomoses were demonstrated in the hamster and human livers. In these latter species, all arterioles terminated into sinusoids adjacent to the portal tracts. No intralobular arterioles were observed in any species.

Assays for, and cross-reactivities of, IgE antibodies to the muscle relaxants gallamine, decamethonium and succinylcholine (suxamethonium)

Two radioimmunoassays have been developed to detect IgE antibodies to succinylcholine, decamethonium and gallamine in the sera of patients who have experienced life-threatening anaphylactoid reactions following administration of a muscle relaxant drug. They involve the coupling of choline and its ethyl analogue, triethylcholine to activated Sepharose. A high degree of cross-reactivity was shown to occur between drug-reactive IgE antibodies and 6 muscle relaxants as well as choline and triethylcholine. Results suggest that the specificities of the IgE antibodies are directed towards quaternary or tertiary ammonium ions on the drugs that bind the antibodies. Molecular models of these compounds support the structure-activity relationships determined in the inhibition studies.

Skin testing in the preoperative diagnosis of anaesthetic allergy

Intradermal testing is a valid manoeuvre for the determination of the drug responsible for an anaphylactoid reaction during anaesthesia. It does not fill criteria for a screening test and will have limited use in the preoperative diagnosis of anaesthetic allergy unless a high risk group is selected.

In vitro diagnosis and studies on the mechanism(s) of anaphylactoid reactions to muscle relaxant drugs

By covalently coupling alcuronium, d-tubocurarine and the pancuronium analogue, vecuronium, and using the resultant complexes in radioimmunoassays with patients' sera, we have found high levels of drug-reactive IgE antibodies in some subjects who reacted to these muscle relaxants. This is the first demonstration of IgE antibodies to such compounds. Assays were also developed for the detection of drug-reactive IgE antibodies to the muscle relaxant drugs succinylcholine, decamethonium and gallamine. They involved the coupling of choline and its ethyl analogue, triethylcholine to activated Sepharose. Results of direct binding and inhibition experiments and correlations with clinical findings demonstrated that the assays are relevant to the detection of succinylcholine-, decamethonium- and gallamine-reactive IgE antibodies in patients who experienced adverse reactions to these drugs. Quantitative inhibition studies revealed that IgE antibodies from most patients cross-reacted with all muscle relaxants tested, other quaternary ammonium compounds and some pharmacologically unrelated drugs including promethazine, morphine, neostigmine and pentolinium. Results showed that the specificities of the IgE antibodies are directed towards quaternary or tertiary ammonium ions on the drugs that bind the antibodies. As these ions occur widely in man's environment in drugs, cosmetics, disinfectants, foods and industrial materials, it seems possible that sensitization of patients may occur without previous exposure to muscle relaxant drugs. Thus, we now have assays that will detect antibodies to all six muscle relaxant drugs --alcuronium, d-tubocurarine, pancuronium, succinylcholine, decamethonium and gallamine-- and, for the first time since the work on penicillins, drug-specific IgE antibodies have been found in large numbers of patients and the allergenic determinants have been identified.

Hilar biliary plexus in human liver. A comparative study of the intrahepatic bile ducts in man and animals

A comparative study of the hepatic bile ducts of man and laboratory animals was made by means of scanning electron microscopy of biliary tract casts. In man, the large intrahepatic bile ducts at the hilum have many irregular side branches and pouches which are all situated in one plane corresponding anatomically to the transverse fissure (porta hepatis). At the bifurcation, some of the side branches from two or three bile ducts communicate with each other. The anastomosing plexus so formed provides communications between the main bile ducts. Bile ducts of the rhesus monkey show a similar but less well developed structure. In the pig, many pouches are observed around not only large but also small bile ducts. No such structures are observed in dog, guinea pig, or rabbit bile ducts. These irregular side branches and pouches correspond to the "vasa aberrantia" and "parietal sacculi" described by L. S. Beale (The Liver. Lecture on the Principles and Practice of Medicine, p 47. London, Churchill, 1889), and they may store and modify bile. The plexus described in man in this report may provide an anatomical basis for incomplete biliary obstruction without cholestasis. A role in biliary atresia and in Caroli's disease is also raised.

The Sunnybrook Gallstone Study: a double-blind controlled trial of chenodeoxycholic acid for gallstone dissolution

The Sunnybrook Gallstone Study was a randomized, double-blind, controlled trial of chenodeoxycholic acid treatment over 2 years in 160 patients with radiolucent gallstones. Sixty-four patients received 750 mg daily, 53 received 375 mg daily and 43 received placebo. Total dissolution of gallstones occurred in 10.9% of patients on 750 mg daily, 13.2% of those on 375 mg daily and in no patient on placebo. The drug was tolerated well. Diarrhea severe enough to cause withdrawal from the study occurred in two patients. No patient developed clinically significant hepatotoxicity. Serum cholesterol rose 10% or more above baseline after 2 years in 33% of patients treated with chenodeoxycholic acid and in 30% of those on placebo. Cholecystectomy was performed in 10.9% of patients on 750 mg daily, 17% on 375 mg daily and 13.6% on placebo. Chenodeoxycholic acid given at these doses dissolved radiolucent gallstones safely but the efficacy was limited.

Nuclear magnetic resonance study of iron overload in liver tissue

Whole-tissue and homogenized samples of human liver were studied in a NMR spectrometer, T1 and T2 relaxation times were measured as a function of added inorganic or organic iron. When inorganic iron (Fe+3) was added, pronounced T1 and T2 shortening was noted. However, when organic iron, in the form of ferritin, was added, the amount of T1 and T2 relaxation enhancement was much reduced for the same amount of added iron. The in vitro ferritin results model the situation found in clinical studies of hemochromatosis. Only in cases of severe iron overload were significant decreases in relaxation times observed. The T2 relaxation time was the more reliable indicator of excessive levels of iron in the liver. The large range of T1 and T2 values encountered in normal volunteers precludes the use of MR to quantitatively measure iron levels in the liver. The T1 and T2 relaxation times measured at intervals for one individual tend to fluctuate as well, making the use of MR to follow the course of treatment of iron overload disorders unreliable.

Role of IgE in anaphylactoid reactions during anaesthesia

As diagnostic methods of detecting drug-specific IgE antibodies become more sophisticated, the evidence implicating specific IgE in anaesthetic allergy has increased. To implicate IgE in reactions, a history resembling anaphylaxis, the demonstration of drug-specific histamine release by intradermal testing and the demonstration of specific antibodies are necessary. Such evidence is seen in 70% of muscle relaxant reactors. Basophil histamine release studies suggest that histamine release is allergen-induced, not direct, and the final evidence necessary is to demonstrate the role of drug-specific antibodies in such histamine release.

Adverse responses to local anaesthetics

Progressive challenge was used to investigate twenty-seven patients with a history of an adverse response to local anaesthesia. True allergy was detected in only one patient. The method does not exclude reactions to additives and preservatives in local anaesthetics. If preservative-free local anaesthetics are used for subsequent exposure in patients with no response to progressive challenge, subsequent exposure is safe. The possibility that some of these patients may be reacting to preservatives in the solutions cannot be excluded by such testing. Where possible preservative-free local anaesthetic preparations should be used for subsequent anaesthesia.

Anaphylaxis

The clinical syndrome of anaphylaxis may be produced by a number of mechanisms. The life-threatening clinical features are angioneurotic oedema, bronchospasm, cardiovascular collapse and pulmonary oedema. The initial treatment consists of general resuscitation plus adrenaline. In shock, colloid solutions should be used to restore blood volume. The pulmonary oedema that occurs is a membrane oedema, and should be treated with artificial ventilation, positive end expiratory pressure, and volume replacement. After a reaction, all available tests should be used to determine the cause, and the patient should be given a warning letter describing the evidence for attributing his reaction to the determined cause. (This should be done in addition to the provision of any identification bracelet.) Pharmacological pretreatment is a valid preventive manoeuvre, but is not 100% reliable.

Resuscitation in acute haemorrhage

While some of the details of resuscitation of the bleeding patient remain contentious, the basic principles are clear. Adequate resuscitation implies the prompt restoration of tissue oxygenation by achievement and maintenance of airway patency, adequate ventilation, cardiac rhythm and intravascular volume. The choice of fluid for primary resuscitation is considerably less important than the care with which it ought to be administered. The volume of fluid required for primary resuscitation varies and there is no well-defined endpoint against which to titrate fluid resuscitation. However, as the complications and mortality of shock are related to the degree and the duration of shock, definitive (usually surgical) intervention should be undertaken early if the clinical features of shock cannot be readily reversed or if the maintenance of clinically adequate perfusion cannot be achieved with the administration of less than 200 ml of fluid per hour.

Nifedipine in ulnar artery occlusion

With the introduction of the calcium channel blocker, Nifedipine, potent peripheral vasodilatation has been demonstrated. Its main action is on the peripheral arterioles and venules with decreased peripheral resistance. Calcium affects most smooth muscle cells of the peripheral arteries and arterioles. Any small increase in the radius of a peripheral vessel or collateral increases the blood flow by an increment of four square. It is not surprising, therefore, that the calcium entry blocker exerts a vasodilatory effect. That effect varies with the intensity of the disease in the vascular bed in the different patients.

Detection of IgE antibodies to suxamethonium after anaphylactoid reactions during anaesthesia

Choline covalently coupled to an insoluble support was used in a radioimmunoassay to detect IgE antibodies to suxamethonium in serum samples from patients who experienced life-threatening anaphylactoid reactions after receiving the drug. Direct binding and inhibition experiments and correlations with clinical findings showed that use of choline in such an assay is relevant to the detection of suxamethonium-reactive antibodies. IgE antibodies were found in 9 of 10 patients who reacted to suxamethonium and whose skin-tests to the drug were positive and in 8 other patients who had reactions to other muscle-relaxant drugs. The positive reactions in the latter group were probably due to cross-reacting antibodies that recognise quaternary ammonium groups on more than one muscle relaxant.

Complement activation during cardiopulmonary bypass by heparin-protamine interaction

Circulating concentrations of split products of the third complement factor (C3c and C3d) were measured in five patients before, during and after cardiopulmonary bypass. In all patients, C3d concentrations increased significantly in samples obtained after the administration of protamine sulphate. Similarly, circulating C3c was seen only in those samples obtained immediately after protamine administration. In vitro experiments demonstrated that activation of the complement system was attributable to the heparin-protamine complex, and was dose-dependent. The activation of complement was not associated with any clinically detectable adverse effects.

Significance of sequential changes in serum complement levels during acute anaphylactoid reactions

Reduced levels of complement fractions C3 and C4 and total hemolytic complement (CH50) are usually attributed to classical complement pathway activation. However, studies in 26 patients undergoing severe anaphylactoid reactions during general anesthesia suggest that these changes may equally reflect plasma dilution and protein redistribution. Twelve patients showed a dramatic fall in complement complexes which tended to resolve after 24 h; however, this fall was not usually associated with the detection of C3 breakdown products or antigen-antibody complexes. Measurement of complement levels is not a reliable index of activation or cleavage when there are dynamic shifts in plasma volume.