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Biomedical subjects

E Hegyi

Publications and source records attributed to E Hegyi.

At least 19 recordsLinked to original sources
PubMed1991

In vitro effects of hematopoietic growth factors on the proliferation, endoreplication, and maturation of human megakaryocytes.

A liquid culture technique was used to study regulation of human megakaryocytopoiesis in vitro. Low-density cells from adult bone marrow were cultured in the presence of normal plasma, plasma from patients with aplastic marrows (AP), recombinant human granulocyte-macrophage colony-stimulating factor (rhGM-CSF) and interleukin-3 (IL-3). Megakaryocytes (MK) were studied at day 10 of culture by a two-color staining technique using a pool of monoclonal antibodies for their identification and propidium iodide to label DNA. Their ploidy distribution was analyzed by flow cytometry. In some experiments cytoplasmic maturation was also studied by ultrastructural techniques. Normal plasma provides a low number of MK with a ploidy distribution including 8 N and 16 N MK. AP promoted in a dose-dependent manner proliferation of MK and some batches favored endoreplication. This effect was clearly demonstrated when ploidy distribution was compared between normal plasma and AP on parallel marrow cultures. However, ploidy distribution was shifted toward low values compared with uncultured MK. rhGM-CSF had no significant effect on these two parameters. In contrast, rhIL-3 from 0.1 U/mL to 100 U/mL had a proliferative effect but was unable to induce endoreplication. Furthermore, when associated with AP it totally abrogated the effect of AP on endoreplication because in most experiments more than 90% of MK were 2 N and 4 N. This effect was also observed when rhIL-3 was added after 7 days of culture (when it has little proliferative effects). Studies of the maturation of MK grown with rhIL-3 indicate that the majority were small mature cells synthesizing alpha-granules and demarcation membranes. The effect of AP on MK proliferation and endoreplication was not related to IL-6 because its IL-6 content was identical to that of normal plasma and its neutralization did not modify these parameters. In conclusion, this study indicates that liquid culture technique in association with flow cytometry could be a powerful tool in identifying the humoral regulators of human megakaryocytopoiesis.

Anemia, Aplastic↗
PubMed1991

Developmental changes in human megakaryocyte ploidy.

Megakaryocytes (MK) obtained from the differentiation of MK colony-forming units (CFU-MK) were grown from fetal liver, cord blood, and adult marrow in liquid culture containing aplastic plasma. Ploidy distribution was studied by a double-staining technique and flow cytometry and MK maturation by ultrastructural techniques. Cultured MK from fetuses and neonates were small sized (about 10 microns) in comparison to adult MK. They were mature cells that contained large membrane complexes as previously found in vivo. Only 2N and 4N MK were usually present in 8- to 10-week-old fetus cultures; 8N MK were detected at 20 weeks of gestation and in neonates. Higher ploidy classes were present in culture from adults but with a much lower frequency than in marrow. Therefore, a progressive shift to higher ploidy and an increase in MK size were observed simultaneously during development. Interleukin 3 (IL-3) increased MK proliferation as in adults but abrogated MK ploidization of 20-week-old fetus culture. The present results suggest that the changes occurring during ontogenesis are related to intrinsic MK modifications because no inhibitor of MK ploidization could be detected in fetal cultures.

Aging↗
PubMed1990

Regulation of human megakaryocytopoiesis: analysis of proliferation, ploidy and maturation in liquid cultures.

A liquid culture technique associated with either double staining and flow cytometry or electron microscopy was used to study human megakaryocytopoiesis. During development from the embryo to the adult, a progressive increase in ploidy classes associated with an enhancement of megakaryocyte (meg) size was observed. Granulocyte-macrophage colony-stimulating factor had no effects on adult marrow cultures. In contrast, interleukin (IL) 3 induced a marked proliferation, but was unable to promote polyploidization. Furthermore, it abrogated the effects on endomitosis of aplastic plasma (AP). This negative effect on polyploidization of IL-3 could be partially dissociated from its effects on proliferation by a delayed addition in culture. AP acted on both proliferation and endoreplication, which was not due to the main hematopoietic growth factors, including IL-6. A synthesis of IL-6 was detected by in situ hybridization in cultured cells including megs which also express receptors for IL-6. These results suggest that terminal meg differentiation may be regulated by an autocrine IL-6 loop, and that megakaryocytopoiesis may be independently regulated at early and late stages of differentiation.

Autoradiography↗
PubMed1990

[Propolis allergy].

The incidence of propolis contact sensitivity was 1.2-3.3% among 7483 hospital patients during the period 1981-1987, while the prevalence among 1,558 healthy volunteers was 0.64%. A group of 26 patients with contact allergy to propolis was challenged with identified substances isolated from propolis. The mixture of 3-methyl-2-butenylester (3M2B) and 3-methyl-3-butenylester (3M3B) from caffeic acid caused a positive reaction in 7 patients, and in 5 of 9 patients there was a positive reaction to the mixture of 3M2B and 3M3B from diacetyl-caffeic acid. Among the 19 patients challenged with the flavonoid group, 3 had positive reactions, and individual derivatives of cinnamic acid caused positive reactions in 3 and 4 patients each. When five components taken from poplar buds were tested, the one that provoked the largest number of positive reactions was the methanol component (15 of 19 patients). The results show that propolis contact allergy is not caused by one main allergen, but by several allergens varying in chemical composition; the presence of these in propolis depends on the nature of the source plant and the place and time of collection by the bees.

Adult↗
PubMed1990

Immunogold probing of platelet factor 4 in different ploidy classes of rat megakaryocytes sorted by flow cytometry.

Different ploidy classes of rat megakaryocytes were sorted by flow cytometry from highly purified perfusion-fixed megakaryocyte cell suspensions prepared by sequential centrifugal elutriation and Percoll gradient centrifugation. Sorted cell populations were studied for the localization of platelet factor 4 (PF-4) probed with the monoclonal antibody 2E7 in order to clarify the relevance of PF-4 localization to the cytoplasmic and nuclear development of megakaryocytes. The relative numbers of labeled alpha granules and labeled alpha granule-related small vesicular structures (AGR-SVS) were quantitated using the gold-labeled antibody detection method and correlated with DNA content and cytoplasmic maturation in individual megakaryocytes. We determined that the stage of cytoplasmic maturation exerted a significant effect on the proportion of labeled alpha granules and labeled AGR-SVS. A significant interaction effect of stage and ploidy class resulted in the stage effect on proportion of labeled alpha granules being significant only in two of the three ploidy classes. The least mature cells present within each ploidy group exhibited PF-4 labeling mostly in SVS that were not related to alpha granules. During subsequent cytoplasmic maturation, more of the labeled SVS were seen related to alpha granules, with more of the mature alpha granules themselves becoming labeled. Polyploidization also affected the proportion of labeled AGR-SVS. Our data suggest that SVS play a role in the intramegakaryocytic transport of PF-4 into alpha granules. These data provide evidence of the complexity of megakaryocytic differentiation involving both cytoplasmic maturation and nuclear endoreduplication as reflected in PF-4 expression.

Animals↗
PubMed1989

Ultrastructural localization of platelet factor 4 in rat megakaryocytes and platelets by gold-labeled antibody detection.

The pattern of distribution of platelet factor 4 (PF-4) was studied in rat platelets and megakaryocytes following immunohistochemical labeling with a monoclonal antibody (2E7) specific for PF-4 and visualization by a protein A-gold complex. We observed a heterogeneity in PF-4 expression among alpha granules with a minority of them being unlabeled by immunoelectron microscopy, a pattern similar in both mature, circulating platelets and developing megakaryocytes. Furthermore, the majority of the labeled alpha granules in both cell types displayed a unique, eccentric localization of the PF-4 that was mainly over the nucleoid region within each granule. This localization is similar to the microtubular localization in alpha granules reported previously for von Willebrand factor and yet distinct from the reported random distribution of fibrinogen. We also observed significant labeling of small vesicular structures in developing megakaryocytes that may be involved in the transport of PF-4 and its packaging in platelet alpha granules. This new information is important in relating patterns of PF-4 biogenesis in megakaryocytes to conditions of alpha granular dysfunction in platelets.

Animals↗
PubMed1988

Hereditary angioedema in Czechoslovakia. Clinical, immunological, genetic and therapeutic studies of 16 families.

The analysis of the findings in 16 families with hereditary angioedema detected in Czechoslovakia over the years 1975-1986 is being presented. In 14 families C1-inhibitor deficiency and in two families afunction of C1-inhibitor was established. Of the total number of 175 examined family members C1-inhibitor defect was registered in 66 subjects (60 with deficiency and 6 with afunction), and of these 48 suffered from clinical symptoms of edematous attacks affecting the skin, larynx, intestine and urinary tract, whereas 18 subjects were asymptomatic. Genealogical studies confirmed that the defect is inherited as an autosomal dominant trait. In 16 patients long-term prophylactic treatment with Danol was introduced. The effective minimum dosage was tested individually for each patient.

Angioedema↗
PubMed1987

Epidemiology of nickel allergy.

In 2400 consecutive patients at 8 clinics in 5 countries, nickel hypersensitivity was found in 176 cases (7.3%), 19 male (2.1%) and 157 female (10.5%). The incidence ranged from 15 to 38 cases in 300 patients of every department (5.0% Sofia to 12.7% Erfurt). 60.6% of the nickel positives were schoolgirls or younger than 25 years. The exposure time was 3 years, in 49% 1 year or shorter. Most cases (75%) are not occupationally acquired, but due to costume jewelry (31.8%), wrist watches (23.3%), metal clothing buckles (3.4%) including jeans buttons. Job dependent nickel dermatitis is often (36/51 cases) linked with wet work. Atopic dermatitis was found in 8.3% of female nickel allergy. Nickel positivity without a dermatitis history was seen in 9/176 cases (5%). Nickel allergy will become a sex-indifferent phenomenon in Europe, because of the changing customs of adornment.

Dermatitis, Contact↗
PubMed1979

[Development tendencies of the contact allergy].

The development tendencies of the contact allergy in the given catch-area in the years 1948-1977 are studied here by the help of a systematic examination of the dynamics concerning the hypersensitivity of the population. By means of patch tests applied to 15685 patients/6864 men and 8821 women/reactors are checked up towards 15 contact allergens/hexavalent and trivalent chromium, nickel, cobalt, procaine, paraphenylenediamine, neomycine, mercury bichloride, resorcinol, camomile, paraben mixture, formaldehyde, balsam of Peru, turpentine oil, rubber chemicals, and the connections between the percentage of the reactors and the alterations in the technology of the production as well as of the degree and effektiveness of the preventive measures and of the introduction of new remedies, cosmetics and necessaries for daily use are being determined. At the same time this study and the results achieved by analysis are the basis for preventive measures to be taken according to the characteristics of the contact allergens and in proportion to the possibility of taking such measures.

Allergens↗