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H Ekert

Publications and source records attributed to H Ekert.

At least 37 records · Page 2Linked to original sources
PubMed1976

Studies on the altered electrophoretic type of the factor VIII related antigen.

A distinct sub-group of von Willebrand's disease is characterized by an electrophoretically faster mobility of the factor VIII related antigen. Some of the physico-chemical properties of this variant antigen were investigated in this communication. The effect of temperature was tested by heating aliquots (0.5 ml) for 20 minutes at 45 degrees C, 56 degrees C and 65 degrees C. The variant was found to be denatured at 56 degrees C while the control was denatured at 65 degrees C. The effect of pH was tested by assessing the quantity (Laurell technique) and electrophoretic mobility (two dimensional immunoelectrophoresis) of the antigen in a variety of buffers ranging in pH from 7.0 to 9.5. The quantity of antigen was variable both among variants and controls and the electrophoretic mobility of the variant antigen was faster at all pH's. Molecular weight differences between the variant and controls were not detected since the chromatographic profile of the variant was similar to that of the controls in Sepharose 6 B using a 0.02 M Tris-NaCL buffer at pH 7.0. The affinity of the antigen for human antibody was heterogeneous although the variant exhibited less affinity for one of the human antibodies but not the other. The inhibitory effect was more pronounced in serum than in plasma. Purified IGG, however, did not show any inhibition, as the residual antigen assayed by the Laurell technique, was similar to the expected values. This would imply that non-IgG plasmatic factors could also play a part in the observed inhibition.

Antigen-Antibody Reactions↗
PubMed1976

Family studies of patients with reduced ristocetin aggregation and abnormalities of factor VIII and/or platelet function.

Factor VIII procoagulant activity (VIIIc), antigen (vWa), mobility of the antigen on two dimensional immunoelectrophoresis and platelet function were studied in 9 families with reduced ristocetin induced platelet aggregation rate (RIPA) and/or deficiency of plasma factor(s) required for ristocetin aggregation of washed normal platelets (vWf). the families could be subdivided into 4 groups. Group I showed dominant inheritance and reduced levels of VIIIc and vWa characteristic of typical von Willebrand's disease. All patients had reduced vWf and in 7 of 10 RIPA was reduced. Group II showed normal levels of VIIIc but reduced vWa. All showed reduced vWf but RIPA was reduced in one patient only. There was a good correlation between vWf and vWa and VIIIc in both groups. The bleeding time correlated with vWf in group I but not group II. Group III showed normal or nearly normal VIIIc and vWa but there was an increased mobility of vWa compared to normals and to groups I and II. RIPA was markedly reduced as was the vWf in one patient. Group IV is represented by one child with a strong family history of bleeding, who had reduced RIPA and defective platelet release reaction. The vWf in this child was normal and the ratio between VIIIc and vWa was similar to that seen in carriers of haemophilia. This spectrum of abnormalities of ristocetin aggregation justifies the use of the term 'von Willebrand's syndrome'.

Animals↗
PubMed1976

Evidence of stem-cell competition in children with malignant disease. A controlled study of hypertransfusion.

In a prospective, randomized controlled study, 30 children who were receiving chemotherapy for malignant disease and who were anaemic and neutropenic, were randomized: 18 to receive transfusion to a Hb of 10-12 g/dl (group A) and 12 to receive moderate hypertransfusion to a Hb of 14-16 g/dl (group B). Children in group B had a significantly more rapid rise in polymorph count, lower incidence of infection, and lower incidence of interruption to chemotherapy. The findings of this study provide evidence for the existence of a common stem cell in human marrow, at least for erythroid and myeloid cell lines, and demonstrate that the concept of "stem-cell competition" derived from animal experiments has a human counterpart which is clinically significant.

Adolescent↗
PubMed1976

Improved prognosis in disseminated histiocytosis.

The prognosis for children with disseminated histiocytosis, previously considered poor, has improved dramatically with the application of modern principles of chemotherapy. Fourteen children with histiocytosis were staged clinically as follows: those without organ dysfunction, stage I; those with organ dysfunction, stage II; and histologically (B, benign and M, malignant). They were treated with either oral chlorambucil or combination chemotherapy with vinblastine and other agents. Clinical staging was of value in predicting response to treatment and prognosis, while histologic staging was of less value. Thirteen of the 14 children responded to treatment and are alive 4 to 67 months (median 12 months) after diagnosis. Two of these relapsed on treatment, and they have responded to a change in therapy. Two children relapsed after stopping treatment and were reinduced with reintroduction of similar therapy. Initial response to treatment suggests a favourable outcome, for children who initially responded to treatment but relapsed subsequently responded to either reintroduction of the same treatment or a change in treatment.

Adolescent↗
PubMed1976

Assessment of the value of factor VIII procoagulant and antigen ratio in the diagnosis of carriers of haemophilia.

The detection rate of carriers of haemophilia was evaluated using the ratio of factor VIII procoagulant activity (VIIIc) to factor VIII antigen (VIIIag). In normals the corelation coefficient of VIIIc to VIIIag was 0.82. In 15 obligatory carriers of haemophilia whose VIIIc and VIIIag levels were studied in the authors' labotatory there was no correlation between VIIIc and VIIIag and the ratio of VIIIc to VIIIag was below the lowest normal value in 12 (80%). In all five obligatory carriers whose VIIIc levels were estimated in the referring institution and VIIIag levels in the authors' laborary the ratio was below the lowest normal value. In 17 sisters of haemophiliacs studied here or referred for estimation of VIIIag only, an abnormal ratio was found in seven. Of 25 mothers of haemophilic children without a family history of haemophilia carriers is close to that expected on theoretical grounds but the interpretation of the results is complicated by the small numbers of patients all of whose studies were performed entirely in the authors' laboratory. In two normal individuals, one of who was on a contraceptive pill, there were no fluctuations of the ratio of VIIIc to VIIIag during the menstrual cycle. In one obligatory carrier with a normal ratio there was also no fluctuation. It is concluded here that a measurement of the ratio of VIIIc to VIIIag is a valuable adjuvant in genetic counselling in haemophilia.

Adult↗
PubMed1976

Vincristine toxicity unrelated to dose.

Four children with vincristine toxicity unrelated to dose are described. Fever, haematological toxicity, and abdominal distension occurred 2-7 days after vincristine was given. Convulsions occurred 6-8 days after vincristine in all 4. Inappropriate secretion of antidiuretic hormone was thought to have occurred in 3 patients. 2 patients died during the acute toxicity phase. Necropsy findings did not show neuronal changes which could be directly ascribed to vincristine.

Child↗
PubMed1976

Platelet release abnormality associated with a variant of von Willebrand's disease.

A family with a platelet release abnormality (PRA) is described. The only son also showed a reduced rate of platelet aggregation in response to ristocetin, markedly reduced levels of von Willebrand's factor (vWf, ristocetin cofactor), and increased mobility of factor VIII-like antigen, features which were suggestive of von Willebrand's disease (vWd). No inhibition of vWf was found in his plasma. Family studies showed no evidence of vWd in the mother. The father's investigations showed a low rate of ristocetin aggregation on one of the two occasions when it was tested and low vWf on two of four occasions. Despite repeated testing, the findings in the father did not conclusively rule out the possibility of mild vWd, and it was impossible to determine whether the vWd in the son was inherited or arose as a mutation. The findings in this family suggest a possible relationship between abnormalities of the factor VIII complex and defective platelet function.

Blood Cell Count↗
PubMed1976

Immune function at diagnosis in relation to responses to therapy in acute lymphocytic leukemia of childhood.

Tests of immune capacity were performed on blood from 49 children with newly diagnosed, untreated acute lymphocytic leukemia, and relation to prognosis was determined. Patients were treated with multiple-drug therapy and prophylactic cranial irradiation. Median follow-up time was 16 mo (range 10--37 mo). Principal unfavorable findings at diagnosis were absolute numbers of T lymphoid cells outside the range 850--2500/mul blood, absence of whole blood responses to phytohemagglutinin in vitro, a low titer of complexed antibody, and the presence in serum of free leukemic blast cell membrane antigen. Fourteen patients showed two or more unfavorable findings at diagnosis. Eleven of these have died. Four of the remaining 35 patients have died. A shorter duration of first remission was found among patients with abnormal numbers of T cells at diagnosis. The findings suggest that the immunologic capacity of the patient at diagnosis is an important determinant in responses to therapy.

Adolescent↗
PubMed1975

Ristocetin in the diagnosis of von willebrand's disease: a comparison of rate and percent of aggregation with levels of the plasma factor(s) necessary for ristocetin aggregation.

Percent aggregation and the aggregation rate of platelet rich plasma (PRP) in response to ristocetin (1.75 mg/ml) were measured in 20 normals and 16 patients with von Willebrand's disease (v Wd), with and without the addition of acetylsalicylic acid (ASA). Percent aggregation did not clearly distinguish between normals and patients with vWd. Aggregation rate was normal in only 2 of 16 patients, and after incubation of PRP with ASA 1 of these 2 remained normal. The corrective effect of dilutions of platelet poor plasma (PPP) on the ristocetin response of washed platelets (von Willebrand's factor, vWf) was measured in 21 normals and 12 patients with vWd. All patients with vWd had abnormal levels. There was a significant correlation between aggregation rate and vWf in patients with vWd but not in normals. Both tests appear to measure closely related defects, and the aggregation rate is as specific as the vWf level for the diagnosis of clinically affected patients.

Antigens↗
PubMed1975

Intermittent chemotherapy and immunotherapy with BCG in remission maintenance of children with acute lymphocytic leukemia: effects upon immunological function.

Twelve children with acute lymphocytic leukemia who had been in complete remission on continuous chemotherapy for at least 12 months, were treated with intermittent courses of chemotherapy alternating with BCG inoculation during the drug-free intervals. Measurements were made of leukocyte populations in blood and bone marrow leukemic blastogenic responses of blood lymphoid cells to phytohemmagglutinin and soluble leukemic blast cell membrane antigen. Antibody titers to a soluble leukemic blast-cell membrane-derived antigen were determined. Comparison was made with similar measurements during a second phase of intermittent chemotherapy without BCG inoculation (phase II). Two children showed bone-marrow relapse and two developed central nervous system leukemia during the study. Rises in blood and bone-marrow lymphoid cell numbers were found during both phases of the study. Blastogenic responses to phytohemagglutinin, depressed at the start of the study following at least 12 months of continuous chemotherapy, rose during intermittent chemotherapy and BCG and remained within normal ranges during phase II. Antibody titers and blastogenic responses to leukemia blast-cell membrane antigens increased in eight of twelve and six of seven children respectively during the BCG phase and were maintained during phase II. Only one child showed further increases in phase II. The combination of BCG and intermittent chemotherapy may increase leukemia-associated immunity in some patients with acute lymphocytic leukemia in remission. The separate contributions of either BCG or intermittent chemotherapy in producing this effect cannot be determined by this study.

Antibodies, Neoplasm↗