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Biomedical subjects

E Kelemen

Publications and source records attributed to E Kelemen.

At least 73 records · Page 4Linked to original sources
PubMed1980

Macrophages are the first differentiated blood cells formed in human embryonic liver.

Up to 70% of free, intravascular hemopoietic cells belonged to the macrophage series in half-thin sections prepared from the liver of a 4.5 week old human embryo (fertilization age) and 50 to 10% were found in the liver sinusoids up to the end of the 7th week. The number of apparent macrophage precursors could reach 10% of cells of the series. Intravascular macrophage clusters were discovered; the majority of contributing cells were phagocytic. The percentage of circulating macrophages in smears was only 0.5% or less during the investigated time period. Peak values for yolk sac macrophages did not exceed 10% of intravascular cells, and apparently followed peak values found in the liver. In half-thin sections large, pale, endodermally located hemocytoblasts of the definitive series also appeared during the 5th gestational week, but the amount of these cells was less than 5%. Their relation to the intrasinusoidal macrophage has not been proved till now. So, the first differentiated definitive blood cells apparently formed in, or at least preferentially attracted to the liver are not definitive erythroblasts, but macrophages.

Cell Differentiation↗
PubMed1978

Ontogeny of human neutrophil granulocyte alkaline phosphatase.

Human embryonic neutrophils (N) in the liver (from 8.5 mm crown-rump length) are alkaline phosphatase (AP) negative during the first trimester of pregnancy. Early bone marrow granulocytes (from eleventh to sixteenth weeks of gestation) behave similarly. Only a small percentage of slightly AP positive cells could be found. Occasional cells with strong NAP reaction appear in the second trimester. NAP positivity greatly increases in the third trimester and term-babies have a somewhat higher than normal NAP activity in circulating blood. Unlike NAP reaction, naphthol-AS-D-chloroacetate esterase and peroxidase reactions are positive even in the earliest (AP negative) neutrophils.

Alkaline Phosphatase↗
PubMed1977

Chronic idiopathic myelofibrosis. A reversible disease?.

A patient with chronic idiopathic myelofibrosis was subjected to splenectomy 1 year after diagnosis. As a clinically unexpected finding, lymph node biopsy suggested the presence of non-Hodgkin lymphoma. The patient was subjected to intensive combined cytostatic therapy. In the following months, signs and symptoms of myelofibrosis regressed remarkably. The patient died 31 months after splenectomy in massive gastrointestinal bleeding. At post-mortem, myelofibrosis could not be detected in three bone marrow areas and a regular, fat-containing, hypercellular marrow was present. The nature of the previous lymph noede pathology was reconsidered, and angioimmunoblastic lymphadenopathy was diagnosed.

Antineoplastic Agents↗
PubMed1977

Specific thrombopoietic inhibition by syngeneic platelet homogenates.

Injections of 1 to 2.5 X 10(8) syngeneic, uninjured platelets did not diminish the circulating platelet count nor the bone marrow megakaryocyte content in mice, and did not influence the incorporation of 75selenomethionine into circulating platelets. However, platelet homogenates, prepared by repeated freezing and thawing of identical amounts of syngeneic paltelets induced a dose-dependent thrombocytopenia along with a diminution on bone marrow megakaryocyte content, and a decrease in 75 selenomethionine incorporation. Other circulating blood cell counts were not diminished after platelet homogenates, and three intravenous doses of homogenates prepared from 0.7 to 1 X 10(5) syngeneic buffy coat cells failed to influence circulating platelet count or 75 selenomethionine incorporation.

Animals↗
PubMed1976

Intimate contact between human yolk sac endoderm and haemopoietic precursor cells.

Although the localization of embryonic haemopoietic cells in the endodermal epithelium of the human yolk sac had been discovered several decades ago, the nature and significance of the localization were dubious, and it was supposed that light microscopic pictures represent technical artifacts. Our ultamicrographs now demonstrate that at 16--26 mm CR-length there is an intimate contact between yolk sac endoderm and free haemopoietic precursor cells: apart from interdigitations various types of intercellular contact could be discovered. These contacts, especially the gap-like ones with associated electron dense cytoplasmic areas speak for intercellular communication, i.e., the role of endoderm in early human embryonic haematopoiesis appears likely. The demonstrability of these contacts, however, does not mean that endodermal associations are indispensable for haemopoietic differentiation.

Endoderm↗
PubMed1976

Absolute alkaline phosphatase positive and negative neutrophil counts in chronic granulocytic leukemia.

Absolute counts for the alkaline phosphatase positive (AP+) fraction of potentially AP+ neutrophils were measured cytochemically during the course of chronic granulocytic leukaemia (CGL), from the clinical onset of the disease. In a previous study of different kinds of severe granulocytopenia, the AP positivity of circulating neutrophils appeared to indicate a kinetic parameter. Early release of mature, non-stored bone marrow granulocytes apparently furnished more AP+ neutrophils, whereas release of stored cells furnished more AP- cells. If we consider enzyme activity to indicate a kinetic parameter, its differential diagnostic usefulness would be less than generally supposed. One hundred and forty eight determinations in 74 CGL patients showed that low AP values are valid for CGL statistically, especially between the 2nd to 5th years of clinical disease, but normal or higher counts of circulating AP+ fraction of mature neutrophils could be found in one fourth of advanced cases (blastic metamorphosis excluded), and even more (17/37) in the earliest period of the CGL process. A similar tendency appears to be detectable in the absolute counts for circulating AP- cells.

Alkaline Phosphatase↗