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Biomedical subjects

J Hofman

Publications and source records attributed to J Hofman.

At least 55 records · Page 3Linked to original sources
PubMed1982

Anaphylactic histamine release during inhibition of the proteolytic and kinin-forming system in experimental animals.

The experiments were carried out on immunized guinea-pigs. Histamine concentration in the blood and the lung tissue, the plasma prekallikrein and kininogen levels, kininase and fibrinolytic activity were determined. The examinations were made before antigen challenge, during anaphylactic reaction and after pharmacological inhibition of proteolysis. As protease inhibitors--Trasylol and EACA were used. The inhibition of the kinin and fibrinolytic systems by Trasylol and EACA did not markedly affect the allergic symptoms and did not change the high level of blood and lung tissue histamine. These experiments suggest that activation of the kinin system is not essential for the initiation of the immediate response but is the consequence of immunological release of histamine and other mediators.

Anaphylaxis↗
PubMed1982

Direct radioimmunoassays for "aldosterone" and "18-hydroxycorticosterone" in unprocessed urine, and their use in screening to distinguish primary aldosteronism from hypertension.

For distinguishing primary aldosteronism from essential hypertension, we use simple direct radioimmunoassays for "aldosterone" (aldosterone and other materials that react with the antibody to aldosterone) and "18-hydroxycorticosterone" (similarly) in unprocessed urine. Patients with primary aldosteronism have high values for "aldosterone." This diagnosis can be validated by assays of further urine samples from the same person and by additional direct assays for "18-hydroxycorticosterone." In none of 65 urine samples from 26 patients with primary aldosteronism were both "aldosterone" and "18-hydroxycorticosterone" values within their reference intervals. However, a few "aldosterone" and "18-hydroxycorticosterone" values for patients with essential hypertension and normal aldosterone excretion were also (moderately) increased. Thus, when high values are found, true aldosterone values must be estimated by extraction and chromatography, to eliminate false positives. The "aldosterone" and "18-hydroxycorticosterone" values by our procedure are much higher than the corresponding values for urinary free aldosterone and 18-hydroxycorticosterone. Although not identified, the immunoactive materials are probably metabolites of aldosterone and 18-hydroxycorticosterone.

18-Hydroxycorticosterone↗
PubMed1981

Antigen-induced histamine release from mast cells and basophils after hydrocortisone and disodium cromoglycate treatment.

The effect of drugs applied in the treatment of allergic diseases such as hydrocortisone and disodium cromoglycate-Intal on the release of histamine during immediate allergic response was investigated. Experiments carried out on guinea-pigs showed that after hydrocortisone administration the blood histamine level fell, whereas the histamine concentration in the lung tissue varied, depending on the time of the drug administration in relation to the antigen challenge. Disodium cromoglycate give before induction of an asthma attack in guinea-pigs lowered the histamine level in the blood and in the lung tissue homogenates. Investigations were also carried out on isolated rat mast cells and human basophils. The stabilizing effect of hydrocortisone was much weaker than that of disodium cromoglycate especially regarding mastocytes. It was found that the extent of histamine release from mastocytes and basophils depends on the concentration of the drugs applied and on the type of antigen used for induction of cell degranulation.

Allergens↗
PubMed1981

Regulation of antibody response to SRBC. II. Effect of a non-specific stimulation.

The ratio of individual 78 isotypes after primary and secondary immunization with SRBC was studied in the strain with a normal formation of IgG antibodies (A/J) and in the strain which responds predominantly by formation of IgM antibodies and only by a low IgG antibody response (C57BL/10ScSn, hereafter referred to as B10). The greatest differences were found in the amount of PFC which produce the IgG2a isotype. In B10 mice the IgG2a/IgM ratio is more than 100 times lower than in A/J mice. The so-called "natural antibodies" to SRBC were detected in both strains and were only of the IgM class; they were slightly higher in B10 mice. Using haemagglutination inhibition test we did not find greater differences between SRBC and erythrocytes of B10 mice than between SRBC and erythrocytes of A/J mice which might explain the lower levels of IgG antibodies after immunization with SRBC. T lymphocytes play an important role for the IgM-IgG switch. This activity of T lymphocytes can be partially substituted by certain substances like LPS or even CFA. We attempted therefore to influence the level of IgG in B10 mice by administration of 10 micrograms of LPS i.p. simultaneously with SRBC. In the high responder strain A/J the administration of LPS led predominantly to an increase in IgG-producing PFC, while the amount of IgM increased only slightly. The effect of LPS on B10 mice was somewhat different. It increased the level of IgG to such an extent that it was comparable to the level seen in A/J mice; however, it also increased the number of IgM-producing PFC so that the final ratio of IgG/IgM remained low in B10 mice.

Animals↗
PubMed1980

Phenol-extracted lipopeptidopoly-saccharide (LPPS) complex from Listeria monocytogenes.

Endotoxin phenol extraction method with subsequent ultracentrifugation and/or chromatographic analysis on Sepharose 2 B column were used to obtain biologically active isolate that turned out to contain polysaccharide, peptide and lipid fractions. The raw phenol extract formed 15% and the LPPS complex, obtained from it by ultracentrifugation, 0.17% of bacterial biomass. The LPPS complex contained 11 amino acids representing about 11% of its dry weight. Similarly as in factor Ei and in analogous extracts isolated by other authors the prevailing amino acids were glutamic acid, aspartic acid and lysine. The LPPS complex contained 1.26% of hexosamine, further hexoses, methyl pentoses and ribose. KDO was not detected. Further this complex consisted of 3% of freely-bound and 5% of firmly-bound lipids, beta-hydroxymyrist acid was not detectable. The composition of fatty acids in the firmly-bound lipid fraction of the LPPS complex differed quantitatively from that both in factor Ei and bacterial cell bodies. The tightness of lipid bonds during purification and the biological role of the Listeria lipids are discussed. On the basis of detected chemical and biological properties, both compatible and incompatible with peptidoglycan, a specific character of endotoxin-like isolates from L. monocytogenes is assumed.

Amino Acids↗
PubMed1978

Thymidine phosphorylation in wheat: analysis of phosphate transfer from ATP to thymidine.

Extracts of wheat (Triticum vulgare Vill. [Triticum aestivum L.] var. Lemhi) seedlings contain thymidine-phosphorylating activity with ATP, ADP, or AMP and nucleotide hydrolase activity (ATP --> --> AMP). The synthesis of [(32)P]dTMP exclusively from [alpha-(32)P]ATP with none detectable from [gamma-(32)P]ATP demonstrates the absence of thymidine kinase and the presence of nucleoside phosphotransferase as the only observable thymidine-phosphorylating enzyme.

Journal Article↗
PubMed1978

Effect of immunosuppressive agents on the blastogenic response of mouse spleen T and B lymphocytes. I. Culture conditions and the evaluation system.

A microplate culture system has been standardized for blastic transformation of lymphocytes, using various mitogens more or less specific to T lymphocytes (concanavalin A, phytohaemagglutinin, erythrogenic toxin) or B lymphocytes (lipopolysaccharides and their lipids A, pokeweed mitogen). The mitogen-stimulated lymphocyte activation was examined by the use of the nucleolar test determining the state of nucleolar RNA synthesis by morphologic criteria. In this introductory paper to a series of papers analyzing the specificity of action of the various chemical and biological immunosuppressive agents on the blastogenic responses of T and B lymphocytes, optimal concentrations of cells and blastogenic substances and other parameters were tested, and the kinetics of transformation was investigated in detail.

Animals↗
PubMed1978

Serum antitrypsin activity and alpha1 antitrypsin level in atopic bronchial asthma.

The aim of our investigations was to evaluate the behavior of the important proteolitic inhibitor--serum alpha1 antitrypsin in patients with atopic and non-atopic bronchial asthma. The inhibitor concentration was determined by means of the immunodiffusion method, and antitrypsin activity was evaluated using the synthetic substrate BAPNA. The investigations were carried out on 53 patients with bronchial asthma and on 13 healthy persons. It was found that in some patients with atopic asthma alpha1 antitrypsin level and antitrypsin activity were very low but this did not lower significantly the mean value of the whole group. The results presented suggest that a relative alpha1 antitrypsin deficiency, at least in some patients, can be considered as being one of the pathogenetic factors in atopic asthma. In addition, determination of serum antitrypsin activity may be of practical significance in differential diagnosis of bronchial spastic reactions of bacterial and allergic origins.

Asthma↗
PubMed1978

The relation between magnesium, blood histamine level and eosinophilia in the acute stage of the allergic reactions in humans.

Investigation of magnesium, blood histamine level and eosinophilia were carried out on 28 bronchial asthma patients during the exacerbation of asthma and in asymptomatic period of the disease. Control group consisted of 30 healthy persons. It was found that during asthma attack in the patients with atopic asthma magnesium level in blood and erythrocytes decreased which is correlated to the rise in histamine level and the number of eosinophils in blood. This relationship was less marked in patients with non-atopic asthma. Results obtained are a further confirmation of the role of magnesium ions in the pathomechanism of immediate allergic reactions in humans and its participation in the immunological release of histamine.

Acute Disease↗
PubMed1978

Blood histamine level and histamine content in the lung tissue in immediate immunological reactions in human and experimental animals.

The blood histamine level was determined in 66 patients with bronchial asthma and 25 guinea-pigs in whom the asthma attacks were induced by histamine or ovoalbumin inhalation after previous immunization of the animals. At the same time, histamine content of the lung tissue of the guinea-pigs was determined. It was found that in both humans and animals the level of blood histamine during immediate allergic reactions rises significantly. The extent of this rise depends on intensity of the reaction and time of determination. In asymptomatic period the blood histamine level did not differ from that of the control groups. Histamine concentration in the lung tissue of many of the animals increased during asthma attack but not in all cases was this increase correlated to the rise in blood histamine level. The reasons for these changes are discussed.

Animals↗
PubMed1977

Surface immunoglobulins on stimulated lymphocytes.

The effect of phytohaemagglutinin, lipopolysaccharide, lipid A and streptococcal erythrogenic toxin on the expression of surface immunoglobulins on nerborn piglet spleen lymphocytes was studied, using iodinated anti-pig Ig, L-, mu- or gamma-antisera. It has been concluded that only IgM is the surface immunoglobulin on non-stimulated as well as LPS-stimulated piglet lymphoid cells. An increase in the numberof labelled cells was observed after cultivation of piglet spleen cells with all the mitogens tested.

Animals↗
PubMed1977

[Development of arrangement and degradation of the system of rough endoplasmic reticulum in antibody-producing plasma cells].

During the immune response of the cells of murine omentum to horseradish peroxidase which had been administered intraperitoneally together together with endotoxin or endotoxoid acting as an adjuvans the plasma cells showed several different patterns of the rough endoplasmic reticulum [RER] system. Irregular to bizarre RER structures occurred plasma cells during the initial phase of the immune reaction only, whereas the plasma cells found at later stages had characteristic highly organized RER systems. The irregular "atypical" RER patterns have been regarded by some authorities as fully functional structures developed under the influence of a rapid differentiation of immunocompetent cells following administration of mitogens as well as due to a variously pronounced toxic influence of mitogens upon cell organelles. The possibilities of RER system degradation and the fate of antibodies which had not been discharged by the plasma cells has been discussed.

Animals↗