A proposal for further standardization of red blood cell glucose 6-phosphate dehydrogenase determinations.

A number of factors were identified which influence the determination of red blood cell glucose 6-phosphate dehydrogenase (G6PD). White blood cells were effectively removed from whole blood by filtration, resulting in a mean reduction of G6PD activity of greater than 1.0 U/g Hb. Optimal enzyme activity was found using haemolysates with a Hb concentration in the range 0.4-1.2 g/dl. At a constant temperature of 30 degrees C, maximum linear rate of activity was achieved between the 10th and 20th min after initiation of the reaction. As a result of these findings, modifications to standardize the assay system were introduced. The new method exhibits excellent precision (CV less than 2.0%) with normal samples, and 95% reference ranges of 7.00-11.15 U/g Hb for adult females and 7.05-10.75 U/g Hb for adult males.

Microcomputer data handling for the Phoenix system.

A modified Phoenix data processing system has been introduced into the laboratories at the Manchester Royal Infirmary. Specifications for the design and installation of microcomputers to link automated instruments to this host computer are described. The operation and data manipulation facilities of the microcomputer are included. It is concluded that these devices aid the management of data within the department and improve the quality of service.

Comparative studies of a new commercial kit for the estimation of vitamin B12 in serum.

A commercial kit method (Technia Diagnostics) for the estimation of serum vitamin B12 claiming certain practical advantages was examined. Analytical and clinical performance were compared with a non-commercial radioisotope B12 method, previously compared to other commercial radioisotope B12 methods. The kit's analytical performance in our hands was satisfactory, although the within-batch precision and recovery of added cyanocobalamin were disappointing. Clinical performance was comparable with the non-commercial B12 method. Establishment of suitable reference ranges as a prerequisite to diagnostic use is apparent.

Comparison of liquid and dried sodium citrate as the anticoagulant for Thrombotest and prothrombin time estimations.

Samples which are taken for the Quick one-stage prothrombin time estimation for the control of patients receiving oral anticoagulant treatment are by convention taken into liquid sodium citrate anticoagulant. Dried sodium citrate has been rejected on the grounds that excessive haemolysis causes activation of clotting factors and therefore falsely short clotting times. Tests were performed with both liquid and dried sodium citrate as an anticoagulant for prothrombin time and Thrombotest. No clinically significant difference between the values given by the two anticoagulants was observed.

An abnormal fibrinogen with delayed fibrinopeptide A release.

Investigation of the family of a patient presenting with haematuria revealed seven cases in three generations showing a prolonged thrombin clotting time. A dysfibrinogenaemia was confirmed when purified fibrinogen from an affected member of the family was shown to also exhibit a prolonged thrombin clotting time. No molecular abnormality could be demonstrated using electrophoretic and immunological techniques. However, using a specific radioimmunoassay to fibrinopeptide A a major defect has been localized to a delay in the rate of release of this peptide by thrombin when the abnormal fibrinogen is converted to fibrin. This case of dysfibrinogenaemia has been tentatively designated fibrinogen Manchester.

An evaluation of commercial radioisotope methods for the determination of folate and vitamin B12.

Five commercial kits for the determination of folate and six kits for the determination of vitamin B12 were investigated. Their performance has been compared with microbiological methods for the two vitamins and with a non-commercial radioisotopic method for B12. The results show the importance of the determination of the reference range for an individual laboratory for each method. The precision of the kits varied appreciably, as did their performance using specimens from patients with different haematological disorders. In particular, certain kits failed to detect all patients with pernicious anaemia. The relative accuracy of the kits was assessed. Various factors which should be taken into account in the final selection of a satisfactory kit are discussed.

Immunotherapy alone vs no maintenance treatment in acute myelogenous leukaemia.

Forty-one adult patients with acute myelogenous leukaemia entered remission induced by daunorubicin and cytosine arabinoside, and subsequently received 6 weeks' consolidation therapy with cyclophosphamide plus 6-thioguanine. They were then randomized to either immunotherapy consisting of intradermal BCG plus allogeneic cells or to "no maintenance". Patients receiving immunotherapy had significantly longer remission (P = 0.039) and survival from remission (P = 0.044) as assessed by the log-rank test. The median duration of first remission for 21 patients receiving immunotherapy was 35.14 weeks, compared with 19.71 weeks for 20 patients on no maintenance, and the median survival from remission was doubled in patients receiving immunotherapy. The value of adequate consolidation chemotherapy is confirmed by the comparatively long first remissions in both groups compared with our previous trials, whilst avoidance of maintenance chemotherapy possibly allowed frequent second remissions and similar post-relapse survival in patients from both treatment arms.

Evaluation of the Hematrak differential leucocyte counter.

The main objectives of the evaluation were to: (1) assess accuracy and precision of cell recognition, (2) establish 'reference ranges' and compare with existing ranges, (3) assess machine reliability and suitability for normal working patterns. The accuracy and precision of the instrument were found to be acceptable, within the limits imposed by counting 100 cells in a wedge smear. Reference ranges compared well with established ranges with the exception of monocytes and eosinophils. the instrument was initially evaluated over a 12-week period and has been in routine use for 18 months durng which time it has been found to be very reliable. It has fitted in with the laboratory working patterns without causing any changes in work flow.

Felty's syndrome.

An unusual case is presented in which a patient complained of oral ulceration and soreness of the mouth and throat. The results of clinical and laboratory investigations are reported and it was concluded that these oral symptoms were associated with Felty's Syndrome. After treatment of oral infection and a dental clearance the patient was virtually symptom-free for five months. The patient had a relapse and was admitted to hospital for treatment of overwhelming infection. Splenectomy was performed without sustained benefit and the patient died six weeks later.

Active immunotherapy in acute myelogenous leukaemia and the induction of second and subsequent remissions.

One hundred and ninety-one adults with acute myelogenous leukaemia were treated with combination chemotherapy consisting of daunorubicin and cytosine arabinoside (Barts III). Sixty-three patients achieved remission and were admitted to one of 3 trials of active immunotherapy: immunotherapy alone, immunotherapy and maintenance chemotherapy or neither of these. All patients had weekly clinical and blood examination and monthly marrow examination. Reinduction chemotherapy was given as soon as relapse was diagnosed in the marrow. The most striking observation was that immunotherapy was associated with easy and repeated reinduction of remission and marked prolongation of survival after first relapse when compared with immunotherapy plus chemotherapy. The possible reasons for this and the value of immunotherapy are discussed in relation to the third trial still in progress which includes 2 maintenance arms, immunotherapy alone and surveillance only.