A theoretical model for respirator cartridge service life for binary systems: application to acetone/styrene mixtures.

A theoretical model, developed previously to assess respirator cartridge service life, was applied to various acetone/styrene binary assault systems. Experimental data, collected for several binary mixtures differing only with respect to the concentration of each of the two compounds, were interpreted in terms of the model. Styrene concentrations varied from 228 to 1578 ppm; the range of acetone concentrations was 92-985 ppm. The specific influence of the compound assault concentrations on respirator cartridge service life was carefully characterized, as break-through curves were generated for both acetone and styrene for each of several different binary systems. Specifically, experimental data for each system were used to determine values of the following theoretical parameters: k'1, tau 1, k'2, tau 2, and Am. These parameters were employed with the theory to generate complete theoretical breakthrough curves and to determine the time-dependence of the weight of each compound adsorbed by the respirator cartridge carbon bed. An interesting phenomenon observed for the acetone/styrene systems was the displacement (from the carbon) of previously adsorbed acetone molecules by styrene molecules. Acetone breakthrough was observed first in each of the systems studied. Following the onset of this breakthrough, the acetone breakthrough concentration was enhanced by the displacement of acetone from the carbon bed by the adsorption of styrene. The theoretical model accurately predicts both this enhancement and the associated breakthrough characteristics of styrene. In addition, the theory is capable of predicting the ratio of the number of displaced acetone molecules to the corresponding number of displacing styrene molecules. For these studies, this ratio ranged from 0.3 to 0.7. The service life of respirator cartridges exposed to acetone/styrene mixtures depends on the assault concentration of each compound and is significantly influenced (shortened) by the displacement phenomenon.

Beta receptor density in human lymphocyte membranes: changing with aging?

The number of beta adrenergic binding sites (Bmax) in human lymphocyte membranes has been reported to decrease, remain the same, or increase with age. In order to address this issue, we used two highly specific beta receptor ligands with lymphocytes from healthy aged (range: 51-90 years) and young (19-39 years) subjects in two separate studies. Because depression can reduce Bmax, potential aged subjects were excluded if they had high scores on tests for depression. Bmax was higher in the aged group of each study (33% higher in the first, p less than .01, and 72.5% in the second, p less than .02); the results were similar in both studies. Antagonist affinity did not differ between young and aged groups in either study. We suggest that some of the discrepancies in the literature could be due to differences in age ranges used or to inclusion of depressed subjects in prior studies.

Inhibition of alpha-ketoglutarate dehydrogenase activity by a distinct population of autoantibodies recognizing dihydrolipoamide succinyltransferase in primary biliary cirrhosis.

Sera from patients with primary biliary cirrhosis contain autoantibodies that recognize mitochondrial proteins. Five of the target autoantigens have now been identified as enzymes of three related multienzyme complexes: the pyruvate dehydrogenase complex, the branched chain alpha-ketoacid dehydrogenase complex and the alpha-ketoglutarate dehydrogenase complex. Each complex consists of component enzymes designated E1, E2 and E3. In this report, we confirm that primary biliary cirrhosis sera react with dihydrolipoamide succinyltransferase, the E2 component of alpha-ketoglutarate dehydrogenase complex. Seventy-three of 188 (39%) primary biliary cirrhosis sera reacted with alpha-ketoglutarate dehydrogenase complex-E2 when immunoblotted against purified alpha-ketoglutarate dehydrogenase complex; one of these sera also reacted with the E1 component. In addition, primary biliary cirrhosis sera possessing alpha-ketoglutarate dehydrogenase complex-E2 reactivity specifically inhibited enzyme function of alpha-ketoglutarate dehydrogenase complex. Enzyme activity was not affected by primary biliary cirrhosis sera that contained autoantibodies to pyruvate dehydrogenase complex-E2 and/or branched chain alpha-ketoacid dehydrogenase complex-E2, which lacked alpha-ketoglutarate dehydrogenase complex-E2 reactivity. Furthermore, affinity-purified primary biliary cirrhosis sera against alpha-ketoglutarate dehydrogenase complex-E2 inhibited only alpha-ketoglutarate dehydrogenase complex activity but did not alter enzyme activity of either pyruvate dehydrogenase complex or branched chain alpha-ketoacid dehydrogenase complex. Finally, alpha-ketoglutarate dehydrogenase complex-E2 specific affinity-purified antisera did not react on immunoblot with any component enzymes of pyruvate dehydrogenase complex or branched chain alpha-ketoacid dehydrogenase complex.(ABSTRACT TRUNCATED AT 250 WORDS)

The relative affinity of recombinant dihydrolipoamide transacetylase for autoantibodies in primary biliary cirrhosis.

In normal individuals there is an adaptive immune response to a foreign antigen in which antibodies of increasing affinity are produced with time. This is not always true of an autoimmune response. However, because only a limited number of autoantigens have been cloned or purified, this issue has not been studied well. In primary biliary cirrhosis the predominant manifestation of autoimmunity is antimitochondrial antibodies that react with dihydrolipoamide transacetylase. The availability of recombinant dihydrolipoamide transacetylase and the development of a rapid and reproducible enzyme-linked immunosorbent assay for autoantibodies has allowed us to address the affinity of autoantibodies using thiocyanate inhibition. Thiocyanate is a chaotropic compound known to inhibit antigen-antibody binding in a concentration-dependent manner. We used this property to inhibit the binding by enzyme-linked immunosorbent assay of human recombinant dihydrolipoamide transacetylase with serum autoantibodies from 55 patients with primary biliary cirrhosis. The relative affinity and serum autoantibody titers were then compared with the histological stage of the liver biopsy sample. Interestingly, we found a considerable heterogeneity of relative affinities. These relative affinities did not correlate with the histological stage or the serum titer of antimitochondrial antibodies. However, the ability of serum autoantibodies to inhibit intact primary biliary cirrhosis enzyme activity was found to correlate highly (R2 = 0.751) with the relative affinity. Thus there are profound differences between patients with respect to qualitative expression of autoantibodies. The significance of this data will be unclear until more is determined regarding the nature of the epitope that drives T cells and leads to B-cell responses.

Primary biliary cirrhosis. Inhibition of pyruvate dehydrogenase complex activity by autoantibodies specific for E1 alpha, a non-lipoic acid containing mitochondrial enzyme.

Antimitochondrial antibodies (AMA) are serologically characteristic of patients with PBC. Four Ag recognized by AMA have been recently identified, including protein X and the acyltransferases of three related multienzyme complexes: the pyruvate dehydrogenase complex (PDC), the branched-chain alpha-ketoacid dehydrogenase complex, and the alpha-ketoglutarate dehydrogenase complex. Each of these enzymes contains one or more lipoyl moieties as part of a major functional site. In addition, epitope mapping has suggested that the AMA target is this lipoic acid-binding region. In this report we demonstrate that sera from patients with PBC also recognize the E1 component (pyruvate dehydrogenase, EC 1.2.4.1) of PDC. PDC-E1 is composed of alpha and beta-chains. Reactivity with the 41 kD alpha chain was detected in 80 of 120 (66%) PBC sera by immunoblotting against purified PDC-E1; 2 of 120 sera also demonstrated reactivity with the 34 kD beta chain. In contrast, sera from patients with SLE, chronic active hepatitis, or progressive sclerosing cholangitis as well as sera from healthy volunteers did not react with PDC-E1. Furthermore, affinity-purified PBC sera against PDC-E1 alpha were able to inhibit PDC enzyme activity, whereas control sera could not. PDC-E1 alpha is now the fifth mitochondrial autoantigen of PBC to be identified. Similar to the four previously identified autoantigens, AMA appear to be directed to a functional site of PDC-E1 alpha inasmuch as they are able to inhibit enzyme function. However, PDC-E1 alpha is also unique in that it is the first identified mitochondrial autoantigen which does not contain lipoic acid.

Antimitochondrial antibodies of primary biliary cirrhosis recognize dihydrolipoamide acyltransferase and inhibit enzyme function of the branched chain alpha-ketoacid dehydrogenase complex.

Antimitochondrial antibodies (AMA) recognizing the acetyltransferase (E2) of the pyruvate dehydrogenase (PDH) complex have been previously well-documented and the immunodominant epitope mapped. In this study, we demonstrate that sera from patients with primary biliary cirrhosis (PBC) react with another lipoic acid containing acyltransferase enzyme, namely the E2 of the branched chain alpha-ketoacid dehydrogenase (BCKD) complex. Indeed, 85/120 (71%) sera from patients with PBC reacted with BCKD-E2 by immunoblotting against purified BCKD complex. In contrast, sera from patients with chronic active hepatitis or progressive sclerosing cholangitis as well as sera from healthy volunteers did not react with any component enzymes of the BCKD complex. More importantly, BCKD enzyme activity was inhibited after incubation of the BCKD complex with either PBC sera against BCKD-E2 or with affinity purified antisera to BCKD-E2. Enzyme activity was unaltered by control sera or with PBC sera that reacted with PDH-E2 but not BCKD-E2. Furthermore, immunoblots of purified mitochondria probed with PBC sera absorbed with BCKD-E2 demonstrated that BCKD-E2 and PDH-E2 are each recognized by distinct AMA populations which do not cross-react. In addition, affinity purified PBC sera against BCKD-E2 did not react with PDH-E2 nor inhibit PDH enzyme activity, thus providing further evidence that BCKD-E2 and PDH-E2 are recognized by separate AMA. These data further suggest that the BCKD-E2 epitope recognized by AMA contains, or is close to, a functional domain of this enzyme. The availability of cDNA clones encoding BCKD-E2 and PDH-E2 will allow the study of how key metabolic enzymes may be involved in the immunology and pathology of PBC.

Lymphocyte beta-adrenoceptor/effector complex in aging and dementia of the Alzheimer type.

We examined density (Bmax), affinity (Kd), and norepinephrine (NE)-stimulated cyclic adenosine monophosphate (cAMP) generation of the beta-adrenergic receptor on lymphocytes in patients with dementia of the Alzheimer type (DAT, n = 13), in normal aged controls (AGED, n = 27), and in young controls (YOUNG, n = 21). Bmax (fmol/mg protein; mean +/- SD) was significantly lower in YOUNG (48.0 +/- 18.7) than in either AGED (64.8 +/- 22.3) or DAT (63.6 +/- 19.5, p less than 0.05). Receptor sensitivity, i.e., the fold increase of stimulated over basal cAMP generation (S/B), was higher in DAT (8.3 +/- 5.2) than in AGED (5.5 +/- 2.3) or YOUNG (5.4 +/- 2.6, p less than 0.07). This difference was due to a significant increase in S/B in female but not male DAT patients compared with AGED (p less than 0.05). There were no differences in levels of circulating NE between DAT and AGED, nor between sexes. Thus, the present data suggest that in this model of the postsynaptic beta-adrenergic receptor/effector complex, receptor sensitivity was increased in women with DAT.

Autoantibodies of primary biliary cirrhosis recognize dihydrolipoamide acetyltransferase and inhibit enzyme function.

Autoantibodies against mitochondria occur in the sera of patients with primary biliary cirrhosis (PBC) with characteristic reactivity to an inner membrane protein of approximately 74 kDa. To precisely define these autoantigens, we recently cloned and sequenced a rat liver cDNA (pRMIT) that encodes for all of the epitopes recognized by Ig to the 74-kDa autoantigen. In the present study we have used this recombinant probe as a tool, in addition to purified enzymes, to demonstrate by immunoblotting that the 74-kDa mitochondrial autoantigen is dihydrolipoamide acetyltransferase (EC 2.3.1.12), the core protein of the pyruvate dehydrogenase complex. Furthermore, and of particular interest, inhibition of pyruvate dehydrogenase enzyme activity was demonstrated after incubation with sera from patients with PBC but not from normal volunteers or patients with chronic active hepatitis. Such inhibition was abrogated by absorption of the PBC sera with an expressing subclone of pRMIT, designated pRMIT-603. Identification of dihydrolipoamide acetyltransferase as the target of autoimmunity in PBC provides a reagent that can be used to determine mechanisms by which this molecule is recognized. It will allow study of whether autoimmune reactivity, at the humoral or T cell level, is the basis for the pathogenesis of PBC. Additionally, such data present evidence of functional inhibition of a critical metabolic enzyme. Dihydrolipoamide acetyltransferase is well-known to mitochondrial biochemistry and, similar to identified autoantigens in other autoimmune diseases, is highly conserved in evolution.

Autoantibodies to mitochondria in systemic sclerosis. Frequency and characterization using recombinant cloned autoantigen.

Mitochondrial autoantibodies, a hallmark of primary biliary cirrhosis (PBC), have been widely described for many years in patients with systemic sclerosis, and there have been several reports of the concurrence of systemic sclerosis and PBC. However, there is very little information with respect to the significance of these autoantibodies or any definitive evidence that the antigens involved represent the mitochondrial autoantigens (M2 complex) described in PBC. We have cloned and sequenced a rat complementary DNA which encodes for all the epitopes recognized by autoantibodies to the major, or 70-kd, mitochondrial autoantigen in patients with PBC. Using this recombinant fused autoantigen, as well as by immunoblotting with human placental mitochondria, we tested for antimitochondrial antibody specificity in sera from 250 patients with systemic sclerosis. Nineteen sera (7.6%), including those from patients with CREST (calcinosis, Raynaud's phenomenon, esophageal dysmotility, sclerodactyly, telangiectasias) and diffuse scleroderma, had reactivity with human placental mitochondria proteins by immunoblot testing. All 19 sera reacted with the M2 complex. All sera that reacted with the 70-kd protein likewise reacted with the recombinant cloned autoantigen. The predominant autoantibody isotype to the 70-kd protein was IgG3. Interestingly, the 70-kd protein is 11% proline, an amino acid which is frequently preceded by hydrophobic amino acids.

A measurement of the process of adolescence: standardization and interpretation.

The Objective Measure of Ego Identity Status (Adams, Shea, & Fitch, 1979) was administered to 350 adolescents (12 to 18 years old) to test the Eriksonian theory of a developmental continuum from role diffusion to identity achievement. The results offer construct validity for the dynamic process proposed by Blos and Erikson, but do not support the categorization procedure as set forth by Adams, Shea, and Fitch. The OMEIS questionnaire lends itself to a qualitative and dynamic interpretation rather than to a quantitative and normative approach. It is suggested that the dynamic interpretation is more sensitive to the psychological reality of the developmental process.

Influence of dietary fatty acid concentration and geometric configuration on murine mammary tumorigenesis and experimental metastasis.

To investigate the influence of fatty acid geometric isomers on the growth and experimental metastasis of mammary tumors, mice were fed diets containing fat high in either cis or trans fatty acids. The cis fat was prepared to have a fatty acid composition similar to that of the trans fat; both were provided at 5 or 20% (by weight) of the diet. Line 168 mammary tumor cells were transplanted: 1) subcutaneously into female BALB/c mice to observe the effects of dietary fat on latency and local tumor growth, and 2) intravenously to observe influences on experimental metastasis. No differences in the latency or rate of primary tumor growth were observed among the groups fed the diets containing cis or trans fatty acids. In addition, there were no differences in fatty acid composition except the levels of trans-C18:1 in the primary tumor cells among the groups fed the experimental diets. Livers and spleens from animals fed both the 5 and 20% cis diet contained significantly more viable radiolabeled tumor cells than those fed the trans diets. Although body weight and composition were not significantly different among the groups, livers from animals fed the diets containing trans fatty acids were significantly heavier than those fed diets containing only cis fatty acids. Thus, trans fatty acids behaved similarly to cis fatty acids with respect to promotion of transplantable mammary tumor growth but trans fatty acids were less effective than cis fatty acids in promoting the blood-borne implantation and distant survival of the tumor cells.