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Biomedical subjects

L Greither

Publications and source records attributed to L Greither.

11 recordsLinked to original sources
PubMed1996

[Morphologic and functional changes in thrombocytes after deep freezing with DMSO].

BACKGROUND: During the past decade much work has been carried out towards establishing the optimum method for cryopreservation of platelets. Among the various cryoprotectants dimethyl sulfoxide (DMSO) has been shown to be the most effective. This report describes ultrastructural and functional changes of platelets during the deep-freezing process with DMSO. MATERIALS AND METHODS: Single-donor platelet concentrates were cryopreserved in liquid nitrogen by use of DMSO. Before, during and after the freezing process samples were taken for analysis of ultrastructure and platelet function. RESULTS: While after isolation and addition of DMSO a normal ultrastructure of platelets could be observed, clear signs of beginning cell necrosis were detected after thawing and resuspension in autologous plasma. Fibrinogen-binding capacity and platelet aggregation were significantly diminished. CONCLUSIONS: Although cryopreserved platelets are characterized by hemostatic effects in vivo, it seems conceivable that these effects could be improved by further development of platelet-freezing techniques.

Blood Platelets↗
PubMed1993

Effects of tumor necrosis-factor on primary human leukemia cells: ultrastructural changes.

We investigated the ultrastructural effects of recombinant tumor necrosis factor alpha (TNF) on primary leukemia cells of 8 patients (4 cases of acute myelogenous leukemia and 4 cases of chronic myelogenous leukemia) as well as on bone marrow cells of 1 normal control. The cells were kept in liquid culture for up to 92 h in the presence of up to 10,000 U/ml of recombinant human TNF without adding colony-stimulating factors. Under these conditions the concentration of viable leukemic cells decreased by 14 to 53%, compared to control cultures. In acute myelogenous leukemia, all cases to some degree developed an enlargement of mitochondria; in 2 cases prominent cytoplasmic processes, and in 2 cases cytoplasmic vacuoles were observed. In chronic myelogenous leukemia, an enlargement and deformation of all cell types was observed to varying degrees. In the normal bone marrow sample only minor cytoplasmic changes occurred. In all cultures apoptotic changes were rarely observed and--if present--were observed also in cultures without TNF. When the DNA of leukemic cells treated with TNF was separated on agarose, no fragments characteristic of apoptosis were visible. Our results demonstrate that TNF does not induce direct cytotoxicity or apoptosis in acute or chronic myeloid leukemias and are compatible with the notion that some leukemic cells may be activated or stimulated by TNF. The mitochondrion appears to be one of the primary targets of TNF. Electron microscopy is useful for monitoring the changes induced by TNF.

Apoptosis↗
PubMed1992

TNF induces cytoplasmic vesicles in actinomycin D-treated K 562 cells.

We report here that tumor necrosis factor alpha (TNF) induces peculiar cytoplasmic vesicles in the human erythromyeloid leukemia cell line K 562, sensitized to the cytotoxic action of TNF by a treatment with the inhibitor of transcription actinomycin D. These vesicles are well delineated ultrastructurally. The formation of these vesicles is characteristic for the combination of actinomycin D with TNF and precedes the changes of apoptosis and cellular disintegration. These vesicles correspond to an intermediate step in the cytotoxicity caused by TNF and may indicate that reactive metabolites are involved in the mechanism of action of TNF.

Cell Division↗
PubMed1991

White cell depletion of single-donor platelet preparations by a new adsorption filter.

A newly developed adsorption filter has been evaluated for the removal of white cells (WBCs) from platelet concentrates. It consists of surface-modified polyester fibers and can be used at the patient's bedside. WBC mean removal rate was 98.8 +/- 0.9 percent, and platelet recovery was 99.0 +/- 0.7 percent. The aggregation curves (ADP, collagen) and hypotonic shock response of platelets were not influenced by the filtration, and the plasma electrolyte and lactate dehydrogenase concentrations were unaffected. Transmission and scanning electron micrographs showed no difference in platelet ultrastructure before and after filtration. Determination of posttransfusion platelet recovery did not reveal any significant difference from that of nonfiltered platelets. The tested filter seems to be a suitable device for WBC depletion of single-donor platelet concentrates at the bedside.

Adenosine Diphosphate↗
PubMed1991

[Storage of thrombocyte concentrates: ultrastructural and functional changes].

Optimal storage of platelet concentrates is still an unsolved problem. The present paper demonstrates changes in morphology and function of stored platelets. Transmission microscopy reveals a loss of organelles as well as a progredient destruction of cell membranes during storage. At the same time in vitro aggregability is clearly diminished. Therefore, further investigations seem to be necessary to improve storage conditions of platelets.

Blood Component Transfusion↗
PubMed1991

[Preparation of leukocyte-depleted thrombocyte concentrate: in-vitro testing of a new filtration system (PL 100)].

A newly developed filter-system (PL 100) for the removal of leukocytes from platelet concentrates was tested. It removes contaminating leukocytes by 99.7 +/- 0.6%. The platelet loss was calculated as 25.7 +/- 9.5%. The filtration process does not influence the filtered platelets; plasma-electrolytes, LDH-concentrations, platelet aggregation curves and serotonin-release remain constant. In addition, platelet ultrastructure is not influenced by the filtration. In spite of the high platelet loss, the tested filter-system seems to be a suitable alternative to the conventional methods for the removal of contaminating leukocytes from platelet concentrates.

Blood Platelets↗
PubMed1990

[Production of leukocyte-poor thrombocyte concentrates: results with a new kind of filter system].

A newly developed filter-system (Sepacell PL) for the removal of leukocytes from single donor platelet concentrates was tested. It removes contaminating leukocytes by 99.9%, the platelet loss was calculated as less than 1%. Platelet ultrastructure and function do not seem to be altered by the filtration. Therefore, the tested filter system seems to be a suitable device for leukocyte depletion of single donor platelet concentrates. Further clinical studies, however, are necessary to prove the efficiency of the filter system in preventing alloimmunization in vivo.

Blood Transfusion↗
PubMedDate not supplied

Prolymphocytic leukemia with suppressor T-cell phenotype: report of two cases.

The clinical course of two patients with prolymphocytic leukemia of the suppressor T-cell phenotype is presented. Diagnosis was established by specific monoclonal antibody tests, cytochemical, ultrastructural and cytogenetic studies. The bone marrow showed a diffuse infiltration with medium sized lymphocytes displaying a prominent nucleolus. Both patients presented with pronounced splenomegaly, diffuse lymphnode involvement, leukocytosis, thrombocytopenia and anemia. One of them was refractory to chemotherapy using CHOP, Asparaginase, IMVP16, and irradiation to the spleen. He benefited from prednimustin and repeated leukaphereses, without reaching complete remission (C.R.). The second patient achieved a C.R. of 4 months duration with CHOP-Bleomycin. Survival was 16 and 11 months respectively.

Female↗
PubMedDate not supplied

Repeated blast crisis (BC) of changing morphology, immunologic phenotype and cytogenetics in chronic myeloid leukemia (CML).

The clinical course of a 66 year old male with CML who experienced several " relapse " BC of changing morphology, immunologic phenotype and cytogenetics is reported. The first BC was of lymphoblastic phenotype, the second of myeloid, the third again of lymphoblastic, and the fourth, terminal BC was not further characterized or treated. Whereas a phenotypic switch from lymphoblastic to myeloid has been documented twice, the sequence of myeloid followed by a lymphoblastic BC has, to our knowledge, not been reported so far. Lymphoblastic BC responded to a combination of vindesine/prednisone and 6-mercaptopurin. Myeloid BC was controlled by an AML-type induction regimen consisting of daunorubicin and cytosine arabinoside. This unusual case demonstrates that relapse BC is not necessarily of the same morphologic and phenotypic lineage as the preceding BC. Moreover, treatment should be adjusted to the predominant cell type in order to prolong survival.

Aged↗