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18 recordsLinked to original sources
PubMed1978

In vitro histamine and serotonin release by radiographic contrast media (RCM). Complement-dependent and -independent release reaction and changes in ultrastructure of human blood cells.

Peripheral leucocytes and platelets from twenty healthy volunteers were incubated in vitro with radiographic contrast media (diatrizoate-Hypaque, iothalamate-Conray and iodipamide-Cholografin) under varying conditions. All radiographic contrast media (RCM) were able to induce histamine release from peripheral leucocytes and the release reaction was dose-dependent. There were individual differences in the sensitivity of leucocytes to different RCM. The highest values (up to 80% histamine release) were found with high concentrations (0.07-0.3 M) of diatrizoate. The addition of normal human serum (NHS) to the reaction mixture led to a further increase in histamine release (P is less than 0.01), probably due to complement activation. The mechanism seems to be mediated by proteins of the alternative pathway, because serum depleted of complement components (factor B, factor D, properdin) did not show this synergistic effect. IgG-depleted serum, however, was able to show the augmented release reaction. Washed platelets incubated with RCM released serotonin in a dose- and time-dependent reaction. The most powerful serotonin-releasing RCM was found to be iodipamide, which produced a release reaction in all people investigated at concentrations of 0.04-0.09 M, while diatrizoate and iothalamate were effective only in half of the tested individuals at high concentrations (0.3 and 0.2 M respectively). The addition of plasma proteins to the reaction mixture inhibited the serotonin release quantitatively. There was no difference in inhibitory potency between autologous and heterologous plasma or serum; sera depleted of various complement components showed similar effects as NHS. The serotonin release was not due to platelet lysis, as determined by the concentration of lactic dehydrogenase present in the supernatant during serotonin release. Incubation of the leucocytes with RCM produced ultrastructural changes, including degranulation of basophils, aggregation of platelets and infiltration of the aggregates by polymorphonuclear leucocytes. The most prominent changes were observed when complement was present in the reaction mixture.

Basophils↗
PubMed1978

Specific immunosuppression of experimental autoimmune myasthenia gravis by denatured acetylcholine receptor.

Specific immunosuppression of experimental autoimmune myasthenia gravis (EAMG) was achieved by the use of a denatured preparation of the acetylcholine receptor (AcChoR) that did not in itself induce the disease. Torpedo californica AcChoR was irreversibly denatured by complete reduction and carboxymethylation in 6 M guanidine hydrochloride. Rabbits immunized with reduced carboxymethylated receptor (RCM-AcChoR) produced antibodies that reacted with both RCM-AcChoR and intact AcChoR. The specificity of anti-RCM-AcChoR antibodies is different from that of anti-AcChoR antibodies because the former are directed to only part of the antigenic determinants present in the intact receptor. RCM-AcChoR, which by itself is completely nonmyasthenic, was shown to be capable of both preventing the onset of EAMG and of reversing the clinical symptoms in myasthenic rabbits. In all cases the therapeutic effect of RCM-AcChoR administration on EAMG was accompanied by a change in the immunological specificity of the antibodies. The crossreactivity between AcChoR and RCM-AcChoR and the nonpathogenicity of RCM-AcChoR appear to be crucial in governing the specific immunosuppressive effects of RCM-AcChoR on EAMG.

Acetylcholine↗
PubMed2026

Potential Contribution of DES (p.Leu88Met) and MYH7 (p.Arg787His) Variants to Familial Restrictive Cardiomyopathy.

BACKGROUND: Restrictive cardiomyopathy (RCM) is a rare, severe cardiac disease with a heterogeneous genetic basis. Both genetic and nongenetic factors contribute to RCM pathogenesis. Identifying the underlying molecular causes is important for diagnosis and family screening. In this study, we investigated the genetic basis of RCM in a 52-year-old woman with a family history of RCM and heart disease. METHODS: Genetic predisposition was evaluated using whole-exome sequencing (WES). Candidate variants identified in the proband were validated by Sanger sequencing and interpreted using bioinformatics tools and the American College of Medical Genetics and Genomics/Association for Molecular Pathology (ACMG/AMP) guidelines. RESULTS: Two heterozygous missense variants were identified: a novel DES c.262C > A (p.Leu88Met) variant and a previously reported MYH7 c.2360G > A (p.Arg787His) variant. The DES variant was absent from population databases and was classified as a variant of uncertain significance, whereas the MYH7 variant has been reported in the cardiomyopathy spectrum, primarily in hypertrophic cardiomyopathy. Although both variants may be relevant to the participant's phenotype, their contribution remains uncertain without segregation and functional studies. CONCLUSION: These findings expand the spectrum of DES and MYH7 variants observed in cardiomyopathy and highlight the need for further segregation and functional analyses to clarify their clinical significance in RCM. Identifying the genetic basis of RCM in this family may improve screening strategies and guide clinical management.

DES↗
PubMed1979

Histamine release and complement changes following injection of contrast media in humans.

Mechanisms responsible for allergic-like reactions following administration of radiographic contrast media (RCM) are unclear. Aortic root blood specimens were obtained sequentially in 6 subjects following injection of RCM into the pulmonary artery during cardiac catheterization. In 5 subjects, elevated plasma histamine levels (up to 80 ng/ml) occurred within minutes. Levels of C3, C4, factor B, and total hemolytic complement activity were decreased in the same specimens. No hemodynamic or clinical abnormalities were noted. These findings support the concept that RCM can liberate histamine in vivo in humans. Complement alterations may be related to localized RCM-protein interaction. It is unclear whether complement changes are related to the RCM-induced allergic mediator release.

Adult↗
PubMed1978

Increased in vitro histamine release by radiographic contrast media in patients with history of incompatibility.

This study was designed to compare in vitro leucocyte histamine release in patients with a history of previous radiographic contrast media (RCM) reactions and normal controls. Peripheral leucocytes of ten patients with a positive history of RCM imcompatibility and nineteen normal volunteers were stimulated in vitro with different RCM in different concentrations and the amount of histamine released was measured in the supernatant. There was a significant increase in histamine release induced by RCM in low doses (0.02-0.1 M) in the patients as compared to the normals. At the high doses (0.2-0.3 M), no significant differences were found. Leucocytes from four of the patients were stimulated preferentially by the dye responsible for the incompatibility. Six patients showed no such preference. The increased "releasability" of the patients' leucocytes could not be transferred by serum. Normal leucocytes, when incubated with serum from "high releasing" patients did not show increased histamine release after stimulation with the respective dye. It is suggested that an excessive non-immunological response of basophil leucocytes to RCM stimulation might, in part, account for the adverse clinical reactions observed. Furthermore, leucocyte histamine release might be a useful diagnostic tool for detecting patients with a high risk of developing contrast media reactions.

Adult↗
PubMed2025

Exploring the c.406 C > T variant in TNNI3 gene: pathogenic insights into restrictive cardiomyopathy.

BACKGROUND: Restrictive cardiomyopathy (RCM) is a rare cardiac disorder characterized by diastolic dysfunction and myocardial stiffness, frequently associated with genetic variants. We aimed to explore the genetic basis of RCM in a diagnosed patient through comprehensive genetic analysis. METHODS: Whole exome sequencing (WES) was conducted on the proband, followed by Sanger sequencing for variant confirmation and familial segregation analysis. In silico tools and structural protein modeling were employed to assess the functional impact of the identified variant. RESULTS: The c.406 C > T variant, classified as likely pathogenic, results in a truncated TNNI3 protein. Bioinformatics analysis highlighted significant structural disruptions, likely impairing sarcomere function. The patient presented with growth retardation, progressive dyspnea, and echocardiographic findings consistent with RCM. Both parents were heterozygous carriers, supporting an autosomal recessive inheritance pattern. The homozygosity of the novel variant identified in this study is a critical factor in the genotype-phenotype correlation observed in this case. CONCLUSION: This study identified the novel c.406 C > T variant in TNNI3 as a potential pathogenic driver of RCM, emphasizing the critical role of genetic evaluations in early diagnosis and management of inherited cardiomyopathies. Further studies are warranted to explore therapeutic interventions targeting TNNI3-related pathologies.

Humans↗
PubMed1978

Nonimmunologic complement activation in normal human serum induced by radiographic contrast media.

Two different radiographic contrast media (RCM), iothalamate and iodipamide, induced the activation of several complement (C) components in normal, genetically C2-deficient and agammaglobulinemic human sera in vitro. This activation was dose dependent and demonstrable by a reduction in whole C as well as C4, C2, C3, and C5 hemolytic activities. C6, C8, and C9 hemolytic activities were unaffected. Concommitant with the loss of C3 hemolytic activity was the appearance of C3 proteolytic cleavage products that were identified by immunoelectrophoresis. Both the loss of C3 hemolytic activity and the production of C3 fragments occurred in the presence of 10 mM EDTA, indicating RCM-induced C3 cleavage occurred without participation of the multicomponent C3/C5 convertases of either the classical or alternative C pathways. Furthermore, loss of C3 hemolytic activity was not due to the direct alteration of the C3 molecule by RCM because purified C3 was unaffected upon incubation with RCM at a concentration that induced 80% reduction in the C3 hemolytic activity in normal human serum. Serum samples obtained from 40 patients, before and 30 min after undergoing i.v. pyelography, revealed no significant change in total hemolytic C activity; 34 patients received sodium and methylglucamine diatrizoate and six received sodium iothalamate. Hemolytic C3 levels were also determined for the six patients before and 30 min after administration of sodium iothalamate and no significant change in activity was detectable.

Agammaglobulinemia↗
PubMed1979

[Clinical and biological forms of cytochrome b5 reductase deficiency].

Twenty-four personal cases of recessive congenital methemoglobinemia (RCM) due to cytochrome b5 reductase deficiency are analysed. They can be divided into two categories: 1) RCM type I, in which cyanosis is the single clinical symptom; 2) RCM type II in which cyanosis is associated with severe mental retardation and bilateral athetosis. The enzyme deficiency is restricted to the red cell soluble cytochrome b5 reductase in RCM type I, whereas in the type II form the enzyme defect is generalized to all tissues, involving both the soluble and the microsomal forms of cytochrome b5 reductase. Different mutations occurring at the same locus might account for this heterogeneity. However the mechanism of brain damage in case of generalized deficiency of cytochrome b5 reductase is still unknown.

Brain Diseases↗
PubMed1978

Histamine release, complement consumption, and microvascular changes after radiographic contrast media infusion in rabbits.

The intravenous injection of RCM into rabbits produced dose-dependent changes in SAP, MVP, and RBCV, as well as plasma histamine and complement concentrations. After infusion of 8 ml/kg Hypaque-50, SAP dropped from 86 +/- 3 mm Hg to 50 +/- 3, MVP from 42 +/- 2 cm H2O to 26 +/- 3, and RBCV from 0.98 +/- 0.11 mm/sec to 0.37 +/- 0.13. The microvascular changes appeared 10 sec after injection and persisted for 10 to 40 min. During the course of the reaction it was observed that leukocytes adhered to the endothelial walls and red blood cells shrank and finally aggregated in the microvessels. The microvascular changes were accompanied by an increase in plasma histamine concentration, with an average of 44 ng/ml after 2 min, and a drop in total plasma CH50 by an average of 46%. Infusion of 8 ml/kg hyperosmolar saline solution (4.1 gm/dl or 1324 mOsm/L) produced initial changes in microvascular parameters which returned to normal within a few seconds. At the same time plasma histamine concentration increases slightly without changes in complement. It is concluded that the hyperosmolar properties of RCM may contribute to the initial hemodynamic changes observed after RCM infusion. However, the prolonged microcirculatory disturbances produced by RCM in rabbits appear to be a direct effect of the chemotoxicity of these compounds. Part of this chemotoxicity might result form initial release of vasoactive mediators such as histamine and activation of the complement system.

Animals↗
PubMed1979

Alteration of human blood cells and changes in plasma mediators produced by radiographic contrast media.

In vitro incubation of human blood cells with iodinated radiographic contrast media (RCM) produced marked effects which were dose-dependent: erythrocytes showed crenation which was reversible; neutrophil leukocytes released the lysosomal enzyme beta-glucuronidase; basophil leukocytes released histamine; and platelets released serotonin as well as beta-glucuronidase. The release reaction could not be attributed to cell lysis, as demonstrated by the release of the cytoplasmic enzyme lactic dehydrogenase (LDH). In normal human serum, RCM produced activation of the complement system with lysis of cells. This RCM-induced complement activation seemed to occur via the alternate pathway. Stabilizers and cations present in the clinically used RCM solutions did not produce any complement changes.

Basophils↗
PubMed1978

Template-specific requirements for DNA synthesis by the Mason-Pfizer monkey virus DNA polymerase: unique aspects.

The biochemical properties of DNA polymerase purified from Mason-Pfizer monkey virus were studied, with respect to synthetic and natural template-primer utilization. Thes studies revealed the following new information about the Mason-Pfizer monkey virus enzyme: (a) Mason-Pfizer monkey virus polymerase was found to prefer template: primer molar nucleotide ratios of 2.5-5: 1 for optimal rates of synthesis with poly(C) .(dG)12-18 as template-primer. (b) Poly(A)-directed synthesis was stimulated by the addition of low concentrations of inorganic phosphate to the reaction mixture. (c) Poly(2' -O-methyl-cytidylate), poly(rCm), was the only template studied for which Mn2+ proved the preferred divalent cation. Combinations of divalent cations stimulated rather than inhibited poly(rCm)-directed poly(dG) synthesis by the Mason-Pfizer monkey virus enzyme. (d) Heteropolymeric regions of rabbit globin mRNA and avian myeloblastosis virus 70 S RNA could be copied by the Mason-Pfizer monkey virus polymerase with oligo(dT), oligo(U) or in the case of avian myeloblastosis virus RNA, endogenous primers. In all such studies, Mg2+ was the preferred divalent cation and a distinct preference for the DNA primer in the reverse transcription of natural RNAs was observed. These new findings necessitated comparative studies with the DNA polymerases from Rauscher murine leukemia virus and murine mammary tumor virus, as representative type C and type B retroviruses. Although the Mason-Pfizer monkey virus enzyme was found to share some properties in common with both type C and type B mammalian viral enzymes, certain of the above properties rendered it unique among the polymerases examined.

Animals↗
PubMed1977

Acute urticaria and bronchospasm following radiographic contrast media in a dog.

An immediate-type systemic reaction in a dog following intravenous radiographic contrast media (RCM) manifested by urticaria and wheezing on one occasion and urticaria alone on another occasion is described. This reactivity disappeared spontaneously and plans to study the mechanisms of such a reaction were not possible. If such reactivity is more persistent in certain other dogs, a model for study of immediate type reactivity to RCM would be available.

Acute Disease↗
PubMed1978

Efficacy of intravenous pretesting and antihistamine prophylaxis in radiocontrast media--sensitive patients.

Intravenous pretesting with radiocontrast media (RCM) was performed in 204 RCM-sensitive patients considered for repeat contrast radiography. Group 1 had vague histories of prior anaphylactoid reaction and negative pretests, and 2 of 41 (4.9%) had reactions upon contrast radiography. Groups 2 to 5 had definite histories of prior anaphylactoid reaction. Group 2 had the radiographic study cancelled: 18 of 21 (85.7%) had positive pretests. Group 3 had positive pretests and underwent contrast radiography, and 9 of 15 (60%) had reactions despite premedication. Group 4 (no premedication) and group 5 (diphenhydramine premedication) had negative pretests, but 11 of 53 (20.7%) and 3 of 71 (4.2%), respectively, developed reactions (p less than 0.001). The reaction frequency in group 3 (posivie pretest) of 12 of 18 (66.7%) was greater than that in groups 4 and 5 (negative pretest) combined (14 of 124 (11.3%), p less than 0.001). Intravenous pretesting identified a high-risk group and diphenhydramine premedication decreased the frequency of reaction in patients sensitive to radiocontrast media.

Contrast Media↗
PubMed1977

Purification and characterization of the DNA polymerase of human breast cancer particles.

Previous studies have identified human breast tumor particles possessing many of the features characteristic of RNA tumor viruses. In addition to the expected size (600 S) and density (1.16 g/ml) these include possession of an outer membrane and an inner one surrounding a "core" containing a DNA polymerase and a large-molecular-weight (70S) RNA possessing detectable homology to the RNAs of the mouse mammary tumor virus (MMTV) and of the Mason-Pfizer monkey virus (MPMV). We report here the purification and characterization of the DNA polymerase from the human breast cancer particles. Its key properties are very similar to those ofthe RNA-dependent DNA nucleotidyltransferase (reverse transcriptase) found in MMTV and MPMV. Thus like these viral enzymes, the purified human breast cancer DNA polymerase exhibits the following three features that together distinguish the known viral reverse transcriptases from normal cellular DNA polymerases: (i) a strong preference for oligo(dT)-poly(rA) over oligo(dT)-poly(dA) as a template for the synthesis of poly(dT); (ii) the acceptance of the highly specific oligo(dG)-poly(rCm) as a template for the formation of poly(dG); (iii) the ability to use a viral RNA (AMV) as a template to fashion a faithful DNA complementary copy; and (iv) its preference for Mg++ over Mn++. In summary, the data described here on the enzyme of the human breast cancer particles add further evidence of similarities to the viral agents associated with the corresponding malignancies in the mouse and monkey models. To date, an enzyme with these properties has not been detected in normal breast tissues or in benign tumors of the breast.

Breast Neoplasms↗
PubMed1977

The effect of magnesium and manganese ions on the structure and template activity for reverse transcriptase of polyribocytidylate and its 2'-0-methyl derivative.

The secondary structure of the hydrogen bonded hybrids polycytidylate-oligodeoxguanylate (poly(rC)-(dG)12-18 and poly (2'-oMe) cytidylate-oligodeoxyguanylate (poly (rCm)-(dG)12-18 was studied at several magnesium and manganese ion concentrations. These hybrids are effective template-primer complexes for the synthesis of poly(dG) by avian myeloblastosis virus (AMV) DNA polymerase under disparate ionic conditions. Circular dichroism spectra and thermal melting data were obtained as a function of ion concentration, including conditions that allow optimum rates of poly (dG) synthesis by each complex. These studies demonstrate that both hybrids can change conformation and stability depending on their ionic environment. Comparison of enzyme activity and physical data suggest that the polymerase recognizes particular secondary structure features. Changes in the activity of the AMV polymerase can be induced by varying the Mg++ and Mn++ concentrations alone and in combination. These variations in enzyme activity are correlated with observed changes in the base-stacking alignment of the synthetic template primers. The ions, therefore, seem to affect enzyme activity by altering the conformation of the polnucleotide complexes.

Avian Myeloblastosis Virus↗
PubMed1979

Biochemical and immunological properties of the reverse transcriptase associated with a hamster retrovirus.

Several properties of an RNA-directed DNA polymerase associated with a hamster retrovirus (HaRV) were examined and found to be similar to other polymerases from mammalian type-C viruses in that the enzyme (i) is more active with Mn2+ than Mg2+, (ii) uses the reverse transcriptase-specific poly(rCm).oligo(dG) template, (iii) possesses substantial endogenous polymerase activity and (iv) is strongly inhibited by homologous antisera and moderately inhibited by antisera directed against other type-C viruses. In contrast to previous reports of polymerases from other hamster viruses, HaRV polymerase is active in endogenous assays and the activity is associated with a 70,000 mol. wt. polypeptide in highly purified virions and with 70,000 and 85,000 mol. wt. polypeptides in fresh, unpurified virus. Only one major peak of polymerase activity eluted from DEAE-cellulose while subsequent elution of this peak from phosphocellulose produced two major peaks of polymerase activity. The mol. wt. of these two peaks were 70,000 and 85,000 by glycerol density-gradient sedimentation. The HaRV reverse transcriptase and p30 were found to be most closely related antigenically to other rodent retrovirus proteins.

Animals↗
PubMed1975

Experience with a new agar culture medium for demonstrating the presence of anaerobic bacteria.

In view of the fact that anaerobic diagnostics have become a matter of primary importance, the authors have developed the RCM medium with certain modifications. Owing to its good keeping quality, this medium can be used also on smaller laboratories for demonstrating the presence of anaerobic bacteria and for carrying out germ counts. It constitutes and adequate base for the anaerobic blood medium and for the Wilson-Blair medium, and also for the determination of the antibiotic resistance of the anaerobic bacteria. The sensitivity of this medium surpasses that of the thioglycollate medium, and is suitable in its carbohydrate-free form also for testing the strains for their sugar-fermentative capactiy. Our work was aimed at serving the anaerobic diagnostics of clinical laboratories, and at serving at the same time the method of demonstrating the presence of anaerobes becoming increasingle important in the food industry.

Agar↗