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Biomedical subjects

M G Nelson

Publications and source records attributed to M G Nelson.

18 recordsLinked to original sources
PubMed1988

Red cell pyrimidine 5' nucleotidase deficiency: determination of nucleotidase activity and nucleotide content using HPLC.

The hereditary deficiency of erythrocyte pyrimidine 5' nucleotidase has been investigated using an HPLC anion-exchange procedure designed to measure both red cell nucleotide content and enzymic activity. Red cell nucleotide profiles were determined using a low pH phosphate buffer salt-gradient system in 20 min, whereas a low pH buffer alone permitted the determination of enzymic activity with each of six different nucleotide substrates in less than 4 min. Both the red cell nucleotide profiles and the enzymic activity of haemolysates from two affected brothers and their children agreed well with previously published values. This unified approach should prove useful for detailed studies of deficiencies involving isoenzymes of pyrimidine nucleotidase.

5'-Nucleotidase↗
PubMed1979

Intralaboratory quality control of hematology. Comparison of two systems.

Two systems for quality control have been compared, viz., the whole-blood control preparation method and the algorithm method using the geometric moving average XB and a new estimator Y. The system involving whole-blood controls has the advantage of simplicity of operation, but the economic cost of commercial preparations is often high. The algorith system has the advantage that results of all the test samples are used in the calculation; to some extent, this provides a buffer against random variation. The number of count-outs in a given channel is related to the precision of the channel, which in turn is a function of the number of determinations and calculations required for that result. An error of around 1% is introduced into the result each time a calculation is performed. A successful quality control scheme should contain elements of both control preparation and algorithm methods.

Erythrocyte Count↗
PubMed1972

An evaluation of the Celloscope 401 electronic blood cell counter.

For counting erythrocytes the instrument was precise, with a mean coefficient of variation of 1.21%. Erythrocyte counts showed close agreement with results obtained on a Coulter A electronic counter of proven accuracy. When the Celloscope 401 was modified by the manufacturers to eliminate electrical interference from other laboratory equipment, satisfactory precision and accuracy for white cell counting was obtained. Using cetrimide diluent the coefficient of variation was 1.6% but when using saponin/saline diluent the coefficient of variation was 3.5%. For leucocyte counting there was close agreement between duplicate tests performed on the Celloscope 401 and the Coulter S. The instrument was capable of satisfactory precision and accuracy in platelet counting, provided that the sedimentation method was used to obtain a platelet-rich plasma. The best results were obtained if a two-step dilution was carried out with a first dilution in 10% EDTA and a second in 2.5 mM cocaine in water. Using this method the precision study indicated a coefficient of variation of 3.11%. Close agreement was obtained between platelet counts on the Celloscope 401 when compared with the results obtained either by phase-contrast microscopy or using another electronic counter. Allowing for predilution and duplicate counts on each sample, the rate of throughput was approximately 32 samples per hour. Throughout the test period, the instrument remained electronically and mechanically stable.

Blood Cell Count↗
PubMed1972

Data processing in haematology.

The output from a Coulter model S is captured by a specially designed silent interface which visualizes the results, automatically prints the data on a continuous paper roll and transmits the information to a card punch located in a data processing room. Further requested test data and patient identification data are subsequently added manually to the punch card. The completed deck of cards is used in an off-line batch mode on a dedicated laboratory computer to format report documents, produce ward listings, and quality control information. A punch card off-line method is also described for blood group and related data.

Autoanalysis↗
PubMed1970

An evaluation of the Fisher Hem-Alyzer.

The Fisher Hem-Alyzer is a multitest sequential discrete analyser with automatic printout of digitized results on paper tape. The instrument is well designed, soundly constructed, and reliable in routine use. Cross contamination from the sampler probe or between the cuvettes is minimal. Accuracy and precision are both highly satisfactory. Although the standard rate of throughput is 32 specimens per hour the instrument can be used at irregular intervals to analyse smaller batches or even individual specimens. In a routine daily service the Hem-Alyzer was capable of handling a workload of 200 specimens per day, requiring three hours of laboratory technician time. The Hem-Alyzer produces only three parameters. By not determining the packed cell volume it is not possible to incorporate the derived indices (MCV and MCHC) into the system and this, in the long term, is bound to be a disadvantage.

Autoanalysis↗
PubMed1969

An evaluation of the autoanalyzer SMA-4.

The Technicon AutoAnalyzer SMA-4 has been systematically evaluated. Carry-over from the sample cups was found to be within an acceptable range. The precision and accuracy of the four parameters determined by the instrument have been investigated. The haemoglobin results were found to be accurate. There was good agreement with leucocyte counts performed on the model A Coulter electronic cell counter. After certain modifications had been made in the manifold, satisfactory degrees of accuracy were also obtained for the erythrocyte counts. Although the determination of the haematocrit by conductance is influenced by a variety of factors, the mean coefficient of variation was found to be 0.83% and 95% of the results agreed within +/- 2% of those obtained by the microhaematocrit centrifugation method.A logistic assessment of the SMA-4 when it was put into routine use indicated the need to select blood samples without excess anticoagulant, to calibrate the instrument before each run, to test for instrumental drift, to use a rapid method of correcting stoppages, and, if concurrent reporting is carried out, to employ the part-time services of a second operator. The presence of dust in the environment was found to have a deleterious effect on both the mechanical and electronic components of the system requiring preventive maintenance. It should be possible, by interfacing an analogue-digital converter and automatic punch, to produce data compatible with records.

Analog-Digital Conversion↗
PubMed1969

Punch card data processing in haematology.

A method of processing haematological laboratory data based on the IBM 870 system is described. As the cards are being punched with the identification particulars of the patient and source of the sample, a worksheet is automatically generated on which the tests are indicated. The results of the laboratory tests are recorded by the technician on the worksheet and reproduced on the punch cards which are subsequently used for the automatic printout of the results on self-adhesive preprinted labels. The resulting report is clear and legible and is transferred onto the request/report document. The data processing is carried out by clerk/typists who have been trained as punch card operators. The present workload of approximately 2,000 items of information obtained from some 170 samples per day is handled by one punch card operator in less than three hours. The punch cards are manipulated in a sorter for quality control purposes and are stored for subsequent retrieval of information.

Hematology↗
PubMed1965

Simultaneous free and bound radioactive vitamin B-12 urinary excretion test.

The absorption of vitamin B(12) following the simultaneous administration of (58)Co B(12) and a complex of (57)Co B(12) with human gastric juice was assessed by measurement of urinary excretion of radioactivity. Sixteen control subjects, 13 patients with pernicious anaemia, and four who had had total gastrectomy were studied. The method proved a reliable means of detecting those with intrinsic factor deficiency.

Anemia, Pernicious↗