Pharmacological characterization of adrenoceptors mediating contractile and relaxant responses to noradrenaline in the longitudinal muscle of guinea-pig ileum

Mechanical responses to noradrenaline (NA) were recorded in longitudinal muscle strips from the terminal and intermediate regions (3-10 cm and 30-40 cm from the ileo-caecal junction, respectively) of the guinea-pig ileum. NA(0.16-1,600 microM) produced a concentration-dependent contraction in the terminal ileum with the EC50 value of 11.9 +/- 4.3 microM (n = 5). In the intermediate ileum, NA produced relaxation at concentrations ranging from 0.016 microM to 1.6 microM. Responses to NA at 16 microM varied among preparations: no noticeable change in tension, a moderate relaxation and a small contraction. At higher concentrations, NA produced contractile responses and their peak tension increased in a concentration-dependent manner. The contractile effect of NA in the terminal ileum remained unaltered after treatment with propranolol (1.4 microM) or yohimbine (1.1 microM), or a combination of these drugs. In the intermediate ileum, the relaxant effect of NA was markedly reduced or abolished by propranolol (1.4 microM). Yohimbine (1.1 microM) had little effect on NA-induced relaxation. The contractile effect of NA in both the terminal ileum and intermediate ileum was inhibited by prazosin (1.1 microM), so that the contractions were converted to relaxation or markedly reduced. Propranolol abolished the relaxant response induced by NA at 0.16 microM, but did not inhibit those induced by NA at 1.6 microM. Methoxamine (0.16-1,600 microM) produced a concentration-dependent contraction in both the terminal ileum and the intermediate ileum. The EC50 was 93.5 +/- 28.5 microM (n = 8) in the terminal ileum and 83.3 +/- 27.7 microM (n = 10) in the intermediate ileum. There was no significant difference between the values. The results showed that NA is capable of producing contraction or relaxation in the longitudinal muscle layer of the terminal and intermediate regions of the guinea-pig ileum. The contraction, which is mediated by alpha 1-adrenoceptors, predominates in the terminal ileum, but relaxation, which is mediated by beta-adrenoceptors and uncharacterized adrenoceptors, predominates in the intermediate ileum.

Metabolic requirements for induction of contact hypersensitivity to immunotoxic polyaromatic hydrocarbons

Experiments were performed to define the metabolic requirements for induction of contact hypersensitivity to polyaromatic hydrocarbons (PAHs), environmental xenobiotics that are both immunotoxic and carcinogenic. Evidence that conversion of the parent compound to a reactive metabolite was necessary for the development of contact hypersensitivity included the fact 1) that contact hypersensitivity to the polyaromatic hydrocarbon dimethylbenz(a)anthracene (DMBA) only occurred in strains of mice that could metabolize the compound, 2) that among the PAHs, only those that could induce aryl hydrocarbon hydroxylase, the rate-limiting enzyme in the PAH metabolic pathway, were immunogenic, and 3) that inhibitors of PAH metabolism reduced DMBA contact hypersensitivity. Cells from the XS52 Langerhans cell-like dendritic cell line were able to metabolize the PAH benzo(a)pyrene to its diol, quinone, and phenol metabolites. GM-CSF augmented benzo(a)pyrene metabolism in XS52 cells. Finally, in vivo depletion of CD8+, but not CD4+, T cell populations inhibited contact hypersensitivity to DMBA. The implications of these experiments are that at least for some contact allergens, the metabolic status of the host is a key determinant of individual susceptibility to the development of allergic contact dermatitis, and the metabolic pathway of an individual hapten may have ramifications for the T cell subpopulation-CD4 or CD8-that is activated.

Metabolic requirements for induction of contact hypersensitivity to immunotoxic polyaromatic hydrocarbons

Experiments were performed to define the metabolic requirements for induction of contact hypersensitivity to polyaromatic hydrocarbons (PAHs), environmental xenobiotics that are both immunotoxic and carcinogenic. Evidence that conversion of the parent compound to a reactive metabolite was necessary for the development of contact hypersensitivity included the fact 1) that contact hypersensitivity to the polyaromatic hydrocarbon dimethylbenz(a)anthracene (DMBA) only occurred in strains of mice that could metabolize the compound, 2) that among the PAHs, only those that could induce aryl hydrocarbon hydroxylase, the rate-limiting enzyme in the PAH metabolic pathway, were immunogenic, and 3) that inhibitors of PAH metabolism reduced DMBA contact hypersensitivity. Cells from the XS52 Langerhans cell-like dendritic cell line were able to metabolize the PAH benzo(a)pyrene to its diol, quinone, and phenol metabolites. GM-CSF augmented benzo(a)pyrene metabolism in XS52 cells. Finally, in vivo depletion of CD8+, but not CD4+, T cell populations inhibited contact hypersensitivity to DMBA. The implications of these experiments are that at least for some contact allergens, the metabolic status of the host is a key determinant of individual susceptibility to the development of allergic contact dermatitis, and the metabolic pathway of an individual hapten may have ramifications for the T cell subpopulation-CD4 or CD8-that is activated.

Ethnic differences in the biological consequences of alcohol abuse: a comparison between south Asian and European males

Twenty-two South Asian men and 32 European men who had abused alcohol for at least 1.5 years were studied at the time of admission for detoxification to an Alcohol and Drug Dependency unit. The self-confessed average alcohol consumption during the preceding 3 months was similar in the South Asians (mean 383 g/day) and Europeans (mean 435 g/day) but the total duration of alcohol abuse was significantly shorter in South Asians (geometric mean 7.4 years) than Europeans (geometric mean 13.1 years). The geometric mean values for the concentration of carbohydrate-deficient transferrin in the serum were similar in the two ethnic groups. However, the red cell distribution width, the percentages of HbA1a+b, HbA1c and total HbA1 in red cell lysates and the activities of gamma-glutamyl transpeptidase, aspartate aminotransferase and alanine aminotransferase in the serum were all significantly higher in the South Asians than Europeans. The data suggest that South Asian men who abuse alcohol may be more susceptible to alcohol-related liver damage and acetaldehyde-mediated haemoglobin modification than European men who abuse alcohol to a similar extent for a considerably longer period.

Polyamine induced Z-conformation of native calf thymus DNA

Conformational isomerization of native calf thymus DNA under the influence of spermine, spermidine and putrescine was monitored by UV absorption and immunospecific anti-Z-DNA antibodies. Immunological data indicated increased binding of anti-Z-DNA antibodies to polyamine-perturbed conformations of native DNA and double stranded poly(dG-dC). In the absence of polyamines, anti-Z-DNA antibodies did not bind to either polymers. Analysis of UV absorption studies indicates a left handed conformation of nDNA in the presence of polyamines. Moreover, we observed total aggregation of DNA in the presence of spermine on prolongued incubation. These perturbations in conformation were dependent on polyamine concentration. The results clearly suggest that certain regions of nDNA are sensitive to elevated levels of polyamines and are capable of undergoing B-->Z transition.

Macrophages are a major source of acetaldehyde in circulating acetaldehyde-albumin complexes formed after exposure of mice to ethanol

C57BL mice were depleted of macrophages by an intravenous injection of liposome-encapsulated dichloromethylene diphosphonate (DCMDP), and control mice were uninjected or injected with empty liposomes. One day after injection, a proportion of the DCMDP-treated and control mice was continuously exposed to ethanol vapor for 4 days. Albumin fractions were separated from the sera of both ethanol-unexposed and ethanol-exposed animals and tested for cytotoxicity against a monolayer of A9 cells using two indicators of cytotoxicity: detachment of adherent cells and a decrease in the ability of cells to reduce tetrazolium. The results show that, in mice exposed to ethanol, macrophages are a major source of the acetaldehyde in circulating cytotoxic acetaldehyde-albumin complexes and presumably also of free acetaldehyde.

In vivo effects of vitamin C on the cytotoxicity of post-ethanol serum

The consumption of alcohol is followed by the development in the serum of a non-dialysable cytotoxic activity against A9 cells. This cytotoxicity has been previously shown to reside mainly in unstable acetaldehyde-albumin complexes from which cytotoxic acetaldehyde molecules can be transferred to target cells. The cytotoxicity developing in serum albumin 8 hr after seven healthy volunteers drank 84 g ethanol over 45 min was abolished when the same volunteers were pre-treated with 1 g vitamin C daily for 3 days prior to alcohol consumption. The cytotoxicity was measured against A9 cells using two different indicators: (i) detachment of adherent cells and (ii) a decrease in the ability of cells to reduce tetrazolium. These data suggest that the administration of vitamin C may be useful in limiting those aspects of alcohol toxicity mediated by circulating acetaldehyde.

Correlations between acetaldehyde-modified haemoglobin, carbohydrate-deficient transferrin (CDT) and haematological abnormalities in chronic alcoholism

Serum levels of carbohydrate-deficient transferrin (CDT), the proportions of eight haemoglobin fractions separated by cation exchange liquid chromatography, indices of liver function and various haematological parameters were determined in most of a group of 49 chronic alcoholics who had misused alcohol for at least the preceding 3 months and in 15 healthy non-alcoholic control subjects. The percentages of alcoholics giving abnormally high values for gamma-glutamyl transferase (GGT) activity, CDT levels, GGT activity or CDT levels or both, and aspartate aminotransferase (AST) activity were, respectively, 73.0, 71.0, 87.1 and 64.4. The percentages of patients giving abnormally high values for the proportion of HbA1a, proportion of HbA1ach, proportion of HbA1a or HbA1ach or both, MCH, MCV and red cell distribution width (RDW) were, respectively, 46.8, 25.5, 55.3, 55.3, 36.2 and 29.8. Reduced values for the red cell folate concentration, lymphocyte count and platelet count were found in 36.2%, 6.4% and 17.0%, respectively, of the alcoholics. When compared with the control subjects, the group of alcoholics showed statistically significant increases in the mean values for the MCV, MCH, MCHC and RDW and statistically significant decreases in the mean values for the haemoglobin distribution width (HDW) and the logarithms of the holo-transcobalamin II concentrations and the platelet count. The logarithms of the CDT values correlated directly with the MCV and MCH and inversely with the logarithms of the lymphocyte or platelet counts and the HDW, suggesting but not proving that the haematological changes in chronic alcoholism may be at least partly related to defective glycosylation of the constituents of developing blood cells or, possibly, of haemopoietic growth factors.(ABSTRACT TRUNCATED AT 250 WORDS)

Reaction of 14C-acetaldehyde with whole blood in vitro: further evidence for the formation of unstable complexes with plasma proteins and red cells

When heparinised whole blood was incubated with 5, 10, 45 or 180 microM 14C-acetaldehyde for 1 hr, an average of 33%, 34%, 33% and 41%, respectively, of the radioactivity was associated with red cells and the remainder with plasma. Although 71-80% of the radioactivity in the plasma was TCA-precipitable, only 0.9-3.1% was non-dialysable after 48 hr of dialysis, indicating that much of the acetaldehyde was reversibly bound to protein. When blood was incubated with 10-180 microM 14C-acetaldehyde for 1 hr and the plasma subjected to Sephacryl S300 gel filtration, 0.3-1.9% of the added radioactivity was found in the albumin and IgG fractions; this radioactivity is presumed to reside in both unstable and stable acetaldehyde-protein adducts. Plasma derived from whole blood which was incubated with 5-180 microM acetaldehyde and dialysed for 24 hr displayed cytotoxic activity against A9 cells. These data indicate that when 14C-acetaldehyde is incubated with whole blood, even at concentrations as low as 5-10 microM, a substantial proportion of the radioactive molecules form unstable cytotoxic adducts with plasma proteins and a much smaller proportion form stable adducts. Blood cells (mainly red cells) that were incubated with 14C-acetaldehyde were able to transfer radioactivity to cocultured K562 cells, supporting the possibility that not only acetaldehyde-modified plasma proteins but also acetaldehyde-modified blood cells may transport acetaldehyde and be cytotoxic in vivo.

Higher white blood cell counts and band forms in newborns delivered vaginally compared with those delivered by cesarean section

The authors retrospectively reviewed complete blood counts in the medical records of all babies admitted to a normal newborn nursery from January through December 1989. The subjects consisted of 326 babies who were delivered vaginally (VgD) and 138 who were delivered by Cesarean section (CS). All blood samples were drawn by warmed or unwarmed heel sticks or by venipuncture. The subject's age at the time of blood drawing was similar in both VgD and CS groups (13.4 vs. 13.9 hours, P = 0.51). The number of total leukocytes, neutrophils, band forms, and platelets was significantly higher in VgD newborns than in CS newborns. The mean and standard error of the mean for each of these blood counts (each per microliter) were 23.9 x 10(9) +/- 0.33 versus 21.1 x 10(9) +/- 0.6, 14.6 x 10(9) +/- 0.26 versus 12.8 x 10(9) +/- 0.39, 1.18 x 10(9) +/- 0.08 versus 0.82 x 10(9) +/- 0.08, and 304 x 10(9) +/- 4.1 versus 286 x 10(9) +/- 0.6, respectively (P values for the first three comparisons were all less than 0.005). However, there was no difference between the two groups with regard to hemoglobin, hematocrit, and absolute number of lymphocytes, eosinophils, basophils, and monocytes (P > 0.5). It was speculated that the higher leukocyte, neutrophil, and band counts in VgD babies are the consequences of physical stress and periodic hypoxia, which are more frequent and prolonged with VgD compared with CS delivery. The authors suggest that the mode of delivery should be considered when interpreting blood counts in neonates.

Diamond-Blackfan anemia associated with Treacher-Collins syndrome

We describe a 2-year-old girl with a rare combination of congenital red cell aplasia or Diamond-Blackfan anemia (DBA) and Treacher-Collins syndrome (TCS). The anemia is only marginally responsive to high-dose corticosteroid, and the child is transfusion dependent. There is no one in the family affected with either DBA or TCS. A hypothesis is advanced that the simultaneous occurrence of the dysmorphism and erythroid agenesis in this case may have been the consequences of an insult to the fetus at the critical stage of development of maxillomandibular structure and the stage of primitive erythroid cell migration from the yolk sac to the fetal liver and bone marrow.

Possible role of macrophages in the pathogenesis of ethanol-induced bone marrow damage

Adherent-cell-depleted human marrow cells (MC) were cultured on their own or co-cultured with monolayers of blood-monocyte-derived macrophages or marrow-derived adherent cells with and without 2 mg ethanol/ml for 24 h. The incorporation of 3H-thymidine and 3H-leucine by MC cultured on their own was not significantly influenced by ethanol. By contrast, the incorporation of both radiolabelled compounds was significantly lower in MC from the co-cultures containing ethanol than from those not containing ethanol. This effect was mediated by a diffusible factor produced by macrophages in the ethanol-containing cultures and was independent of intercellular contact. Supernatants from ethanol-containing cultures of marrow-derived adherent cells displayed cytotoxic activity against A9 cells due to the presence of unstable acetaldehyde-albumin complexes. Ethanol inhibited rather than stimulated nitrite production in the MC/marrow-derived adherent cell co-culture system, suggesting that macrophage-derived nitric oxide did not play a role in causing the observed ethanol-related effects. The data indicate that, in the presence of ethanol, macrophages cause inhibition of the incorporation of 3H-thymidine and 3H-leucine into overlying MC, at least partly by oxidizing ethanol to acetaldehyde and releasing some of the potentially cytotoxic acetaldehyde thus formed extracellularly. Bone marrow macrophages may therefore play an important role in the pathogenesis of alcohol-related marrow damage in vivo.

Evidence that long-term survival of concordant xenografts is achieved by inhibition of antispecies antibody production

Antibody and complement have been shown to be of primary importance in the rejection of hamster heart xenografts by rats. Very high anti-hamster antibody titers were detected at the time of rejection of hamster hearts transplanted into untreated or T cell deficient rats. This study demonstrates a method of inhibiting this antibody production by pulse therapy with cyclophosphamide (CyP) and continuous cyclosporine treatment, resulting in a median survival of the hamster heart of greater than 100 days. Controls and CsA-treated rats reject the transplanted hamster heart in a median of 3 days. CyP as a sole therapy resulted in a median survival of 14 days. Prolonged CyP therapy when combined with CsA was associated with increased death among rat recipients due to infection. Antispecies antibody production was suppressed during CyP and CsA therapy and did not recur after cessation of CyP therapy. Cessation of CsA therapy at 60 and 100 days posttransplantation resulted in subsequent rejection of the xenografts (median survival after cessation of therapy of 11 and 19.5 days, respectively) and was associated with production of rat anti-hamster antibodies.

Naturally occurring SLE anti-DNA antibodies recognize unique conformation on DNA-lysine photoadduct

Native calf thymus DNA has been covalently modified with lysine under UV-A light. Human autoantibodies on purification through affinity column of native DNA linked to polylysyl-Sepharose 4B showed almost equal recognition of DNA and photoadduct. The recognition of DNA-lysine photoadduct by the affinity-purified autoantibodies might be helpful in understanding their origin in SLE vis-à-vis the role of positively charged amino acids in the pathogenesis of autoimmune diseases.

Detection of high titres of Toxoplasma gondii antibodies in sera of patients with leprosy in Pakistan

Untreated and treated leprosy patients and their household contacts were screened for antibody to Toxoplasma gondii using antigen-coated latex particles. A significantly high level of seroprevalence (29.6%) was observed in the untreated leprosy patients compared to endemic controls (P < 0.01) with a mean reciprocal antibody titre of 20,007 +/- 3580 (n = 98) in seropositive patients. In treated patients seroprevalence dropped to 13.5%. Seroprevalence in a group of household contacts of leprosy patients was similar to that of control subjects from an endemic area but not exposed to leprosy (7.8% and 6.1% respectively), indicating that the increased seroprevalence in leprosy patients was not merely due to increased exposure related to socioeconomic factors. Antigenic cross-reactivity between T. gondii and Mycobacterium leprae antigens was ruled out by cross inhibition experiments carried out with soluble antigens from each of the organisms. We believe these antibodies may be induced by an increase in T. gondii load in leprosy due to a transient reactivation of latent T. gondii infections, as the antibodies in these leprosy patients were not associated with any sign of eye or lymphatic pathology related to toxoplasmosis.

In vitro effects of vitamin C, thioctic acid and dihydrolipoic acid on the cytotoxicity of post-ethanol serum

The serum of subjects consuming ethanol contains a non-dialysable cytotoxic activity, which is thought to reside in unstable acetaldehyde-protein adducts: the cytotoxic effects have been attributed to the transfer of acetaldehyde molecules from such adducts to target cells. When post-alcohol sera are incubated for 3 hr with ascorbic acid, thioctic acid or dihydrolipoic acid at a concentration of 10-500 micrograms/mL, their cytotoxicity against A9 cells is reduced. Post-alcohol sera incubated with these concentrations of thioctic acid or dihydrolipoic acid also had reduced cytotoxic activity against phytohaemagglutinin-transformed normal human lymphocytes. Studies with artificially produced [14C]acetaldehyde-125I-albumin complexes showed that treatment with thioctic acid or dihydrolipoic acid resulted in a reduced transfer of [14C]acetaldehyde to K562 cells. If these in vitro data also apply in vivo and if circulating acetaldehyde-protein adducts play a role in alcohol-mediated tissue damage, vitamin C and, to a greater extent, thioctic acid may have a beneficial effect in patients with acute and chronic alcohol toxicity.

Activation of the alternative pathway of complement is an important component of hyperacute rejection of rabbit hearts by human blood

Hyperacute discordant xenograft rejection can be simulated by blood perfused working isolated heart. The survival of the heart is dependent on its functional integrity, and the preparation is thus sensitive to early myocardial damage. Perfusion of rabbit hearts with human blood results in immediate graft destruction by a thrombotic process. Prevention of this process results in rapid rejection at about 20 min by the alternative pathway of complement.

Inhibition of rejection of hamster-to-rat heart xenografts

Prolonged survival of concordant organ xenografts as typified by hamster-to-rat heart transplants is difficult to produce. Studies have revealed that T cells are not primarily involved in rejecting such xenografts and that the rat recipients produce high titres of lytic anti-hamster antibodies. In this study, 200 hamster-to-rat cardiac xenografts performed in 30 different experiments revealed that cyclophosphamide (CyP) and cyclosporin A (CyA) could inhibit this antibody production. CyP alone was relatively ineffective in prolonging graft survival (the median survival time was 14 days versus 3 days in untreated controls). Combining CyP and CyA virtually abolished rejection in this model. Four critically timed doses of CyP combined with continuous CyA resulted in recipients not producing anti-hamster antibodies, despite cessation of CyP therapy, and prolonged graft survival time (median survival time was more than 100 days). Cessation of CyA at 60 and 100 days resulted in the rejection of the xenografts and the appearance of the rat anti-hamster antibodies. Xenografts in recipients given only one or two doses of CyP (and continuous CyA) had a median survival time of 7 and 12 days respectively. However xenograft rejection in rats given only 1 or 2 doses of CyP could be averted by complement depletion using a 3-week course of cobra venom factor (CoF) starting on day 4 or day 7 post-transplantation respectively. Discontinuation of CoF after 3 weeks did not result in graft rejection. These results showed that immunosuppressive therapies directed at inhibiting antibody production may be of value in preventing rejection of concordant xenografts. Short-term complement depletion could rescue xenografts from rejection such that rescued grafts appear to be accommodated.

Perfusion of rabbit hearts with human blood results in immediate graft thrombosis, a temporally distinct component of hyperacute rejection

Hyperacute discordant xenograft rejection can be simulated by a blood-perfused working isolated heart. The survival of the heart is dependent on its functional integrity, and the preparation is thus sensitive to early myocardial damage. Perfusion of rabbit hearts with human blood produces immediate graft destruction by a thrombotic process which is a distinct component of hyperacute rejection.

Antibodies against DNA-psoralen crosslink recognize unique conformation

The DNA-psoralen crosslink induced precipitating antibodies in rabbits with a titer of 1:102,400 by direct binding ELISA. The antiserum showed considerable binding with Z-DNA and calf thymus DNA brominated under high salt concentration which has been shown to attain Z-/analogous conformation. Inhibition experiments substantiated the results of direct binding assay. However, the affinity purified IgG showed high degree of specificity for the immunogen and did not recognize nDNA, Z-DNA and brominated DNA as inhibitor. Poly(dG.dC).poly(dG.dC)-psoralen photoadduct was found to be inhibitory. These results indicate that the antibodies are probably recognizing the unique conformation at the site of psoralen crosslinking. The DNA-psoralen crosslink showed significant binding with SLE sera known to have high levels of anti-native DNA antibodies. Affinity purified SLE-IgG in a competition assay pointed out the autoantibody recognition of altered conformation of DNA-psoralen crosslink.

Comparison of the generation of albumin-associated cytotoxic activity in supernatants from ethanol-containing cultures of human blood monocyte-derived macrophages and of two human hepatoma cell lines

The rates of oxidation of ethanol to acetate by human blood monocyte-derived macrophages and the two human hepatoma cell lines PLC/PRF/5 and Hep G2 were studied. The average rates obtained were, respectively, 621, 447 and 596 nmol/h/mg cellular protein. Cultures of these three cell types, containing known quantities of cellular protein per flask, were incubated with 0 or 2 mg ethanol/ml for 72 h and the culture supernatants subjected to affinity chromatography on blue sepharose CL-6B. Pure albumin fractions obtained in this way were adjusted to the same optical density and tested for cytotoxicity against A9 cells. The data showed that the albumin fractions obtained from ethanol-containing macrophage cultures were considerably more cytotoxic than those obtained from ethanol-containing cultures of PLC/PRF/5 and Hep G2 cells. It appeared that, for a given quantity of ethanol metabolised, considerably more acetaldehyde was released extracellularly by macrophages than by the two hepatoma cell lines and that this acetaldehyde bound to albumin to form cytotoxic acetaldehyde-albumin complexes. The data raise the possibility that macrophages are an important source of extracellular acetaldehyde and circulating acetaldehyde-albumin complexes in vivo.