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Biomedical subjects

H J Avenarius

Publications and source records attributed to H J Avenarius.

At least 19 recordsLinked to original sources
PubMed1992

Effect of recombinant human granulocyte colony-stimulating factor (rhG-CSF) on circulating platelets.

The effect on platelets of rhG-CSF was studied in 20 healthy volunteers with the thrombometer, a specially developed device which is described in detail. Additionally, conventional aggregation tests were performed. Low doses of rhG-CSF enhance functional platelet activity, as shown by significant acceleration of the occlusion of the thrombometer channel. Similar results were found in conventional aggregation tests utilizing collagen for induction. At G-CSF concentrations of 0.1 and 1.0 ng/ml the time to response was significantly accelerated and the maximum response was observed in a higher proportion of platelets. However, the second phase of aggregation induced by epinephrine was significantly inhibited by 1.0 ng/ml G-CSF. The activation of platelets may be beneficial in thrombocytopenia, but it may also increase platelet turnover and platelet loss. Further investigation is needed to clarify the mechanism by which G-CSF exerts its effects on platelets.

Adult↗
PubMed1990

[Thrombocyte function and thrombocyte-associated immunoglobulins in patients with systemic lupus erythematosus and chronic polyarthritis].

The investigation of in vitro platelet functions from patients with SLE and rheumatoid arthritis (RA) revealed a distinctly reduced aggregation mass after both collagen und ADP induction. The platelet serotonin contents were significantly decreased in both groups. An "aspirin-like" platelet defect could be excluded by finding a normal malonyldialdehyde release of patients' platelets upon thrombin stimulation. Significantly increased platelet associated IgG was also detected, whereas platelet associated IgM remained within normal limits. These results are interpreted as indicating an ongoing platelet release reaction induced by IgG platelet antibodies, which induce the observed impairment of platelet functions and may also lead to the release of proinflammatory platelet mediators.

Arthritis, Rheumatoid↗
PubMed1990

[Comparison of thrombocyte concentrates of the cell separator AS 104 with preparations of the cell separator CS 3000 (Fenwal)].

Platelet concentrates of the cell separator AS 104 (Fresenius) are compared with those of the cell separator CS 3000 (Fenwal). At each cell separator two platelet preparation protocols and at CS 3000 additionally a WBC preparation protocol was analysed. Platelet counts before and after cellapheresis as well as separation efficiencies show no significant differences between the separation protocols (A, B) and the two cell separators. Platelets of varying volumes show different separation efficiencies. While in WBC concentrates the separation efficiencies of platelets continuously increase from small (2fl) to large (20 fl) platelets, the efficiencies in platelet concentrates decrease in volume range 2 fl-8 fl, and increase in range 8 fl-20 fl. There are no differences between the cell separators. The efficiencies of platelets with 2 fl and 4 fl volumes differ significantly (p less than 0.001) between the protocols A and B of AS 104. After WBC-donation, platelet loss of donors corresponds with platelet yields of the concentrates for the platelet volume range 2 fl-20 fl. Compared with the calculated platelet loss of donors after platelet donation more small platelets with 2 fl-8 fl volumes are found in platelet concentrates. The yields of platelets with 10 fl-20 fl volumes are in accordance with donor's platelet loss.

Blood Transfusion↗
PubMed1990

[Significance of thrombocyte-collagen interaction in arterial laceration].

The interaction of platelets with the extracellular matrix (i.e., collagen) has been the subject of intensive research in the past 25 years. With today's knowledge it is possible to explain why blood loss is minimal in cases of arterial rupture. As discussed earlier, a direct interaction of platelets with collagen was suspected for cellular thrombogenesis in arterial injuries. The first step in this interaction is a loose adhesion of platelets onto mature collagen with activation of the platelets. This is followed by aggregation and activation of the platelets through adhesins, which interact with special glycoproteins of the platelet's surface. At the same time, fibrinogenesis is started and facilitated by expression of platelet-factor 3 from the membrane surface of the platelet, so the production of thrombin is acclerated. The activation of platelets induces mobilization of calcium from the dense tubular system, which is needed for almost all reactions in arterial thrombogenesis. Exogene and platelet-endogene factors are responsible for the platelet activation. The further activation of platelets is maintained by thromboxane A2 and thrombin. The regulation of platelet aggregation is controlled by cAMP and prostacyclin. These well-documented findings are the reason for the very rapid arterial thrombogenesis in cases of arterial rupture combined with a special "fingertrap mechanism" of the scissorlike structure of the adventitia. Therefore, severe hemorrhage is prevented. Even in microvascular lesions the platelet-collagen interaction will be found, so this mechanism must also be considered in the pathophysiology of traumatic compartment syndrome and lung contusion.

Animals↗
PubMed1979

Spontaneous cell-mediated cytotoxicity (SCMC) associated with lymphocytes negative for acid alpha-naphthyl acetate esterase (ANAE) activity.

A modified histochemical procedure for nonspecific acid alpha-naphthyl acetate esterase (ANAE) activity in human lymphocytes was used to identify a subpopulation of E-rosette forming cells. Performing a one hour reaction at pH 6.5 the distinct dot-like staining pattern was almost exclusively observed on high affinity E-rosettes which sedimented readily in a regular Ficoll-Metrizoate gradient. By combining latex phagocytosis with staining for ANAE activity, a clear-cut distinction between mononuclear phagocytes and lymphocytes could be made. An attempt was undertaken to relate the ANAE marker on human lymphocytes to their functional capacity in spontaneous cell-mediated cytotoxicity (SCMC) reactions. Using as targets two allogeneic (K562,IGR3) and a xenogeneic cell line (L1210) it could be clearly demonstrated that high SCMC activity is mediated by ANAE negative mononuclear cells, whereas enrichment for ANAE positive lymphocytes resulted in a loss of SCMC.

Adult↗
PubMed1978

[Effector function of acute leukemias in "spontaneous" (SCMC) and antibody dependent cellular cytotoxicity-tests (ADCC) (author's transl)].

Blood lymphocytes from 13 untreated acute leukemia patients, 3 pre-leukemias 3 immunoblastic lymphadenopathias and one infectious mononucleosis showed significantly lower spontaneous (SCMC) and antibody-dependent cellular cytotoxicity (ADCC) against 51Cr-labeled allogeneic melanoma cells of the IGR3 cell line than effector lymphocytes from 20 age- and sex matched control persons. While control lymphocytes exhibited the highest cytotoxic activity after depletion of mononuclear phagocytes (Fraction FFF), followed by the "Ficoll" purified Fraction F and defibrinated whole blood, the reverse was true for acute leukemias: here, the highest cytotoxicity was found in whole blood followed by the lymphocyte fractions F and FFF. Comparatively high cytotoxicity was found with two leukemia patients who had received blood transfusions the day before testing. During the course of an acute erythroleukemia chemotherapy drastically reduced SCMC and ADCC activities. A therapeutical splenectomy, on the other hand, did not affect cellular cytotoxicity in the case of a hairy cell leukemia. The angioimmunoblastic lymphadenopathies showed strikingly high percentages of EA- and EAC-rosettes forming cells and showed a marked increase of SCMC and ADCC activities after elimination of mononuclear phagocytes from the effector cell population.

Acute Disease↗
PubMed1977

[Thrombophoresis II. Effects of thrombocyte separation on the blood donor (author's transl)].

The separation of approximately 75% of the platelets present in circulation and thrombocyte pool in healthy adult donors by continuous flow centrifugation lowers the mean thrombocyte concentration to 140 +/- 28 X 10(3)/microliter. A dangerous thrombocytopenia can not occur since the platelet count in the reinfused erythrocyte zone remains at around 88 X 10(3)/microliter. The reactive rise of the platelet count after separation, the extend of which depended on the total amount of harvested thrombocytes, reached values around 277 X 10(3)/microliter. The total thrombocyte yield exceeded the calculated yield by 30%, indicating emptying of a quiescent thrombocyte pool. Thrombopoietin activity could be demonstrated in donors' plasma at 12 and 24 hours after thrombophoresis.

Blood Cell Count↗
PubMed1977

[Investigations of the clinical course of acute myocardial infarction. I. The fibrinolytic treatment of acute myocardial infarction with streptokinase (author's transl)].

In 26 hospitals a study was carried out to investigate the influence of fibrinolytic therapy on mortality in hospital in acute myocardial infarction. The study was concerned with the question whether fibrinolytic therapy in acute myocardial infarction could lower the hospital mortality and whether fibrinolytic therapy should be recommended as an additional therapy for any type of hospital, irrespective individual differences in treatment. 483 out of 1463 patients were treated with streptokinase. These patients were randomized in two groups. Group I was treated in the usual way additionally streptokinase was given, group II without streptokinase. Both groups were similar regarding the course of illness and clinical data. It could be shown that the mortality was not significantly lowered by streptokinase. But in case of shock the mortality seemed to be lower after streptokinase, this difference not being significant.

Acute Disease↗
PubMed1977

[Investigations of the clinical course of acute myocardial infarction. II. Epidemiological facts (author's transl)].

1463 patients with acute myocardial infarction were treated in 26 hospitals in Northern Germany from June 1972 till August 1973. The time elapsed between onset of symptoms and admission to the regional hospital was similar in rural patients and those living in cities. 39% were admitted later than 12 hours after onset of symptoms. Having survived the prehospital phase the age of infarction did not influence the mortality. The treatment in the different hospitals was in no way standardized, except the treatment with streptokinase. Regarding this procedure, the following results can be presented. The overall mortality was 25.8%. Mortality was higher in cases of high age, preexisting myocardial failure, diabetes mellitus and in cases of shock and/or arrhythmia. Anterior wall infarction showed a higher mortality than posterior wall infarction. In this study the average results of treating 1463 patients with acute myocardial infarction treated in Northern Germany were presented.

Acute Disease↗
PubMed1976

[The diagnostic value of enzymes in cerebrospinal fluid (author's transl)].

The clinical value of enzyme activities in cerebrospinal fluid (CSF) should be proved by examination of GOT, GPT, LDH and CPK in blood and CSF of 115 unselected and 4 selected patients. Only the GOT showed a significant correlated increase in diffuse vascular diseases in both, serum and CSF. Discussing the literature the authors affirm, that only mechanical or functional lesion of the blood-brain-barrier will increase the enzyme activities in serum and CSF. The origin of these enzymes however is unknown till now.

Alanine Transaminase↗