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Biomedical subjects

R M Rowan

Publications and source records attributed to R M Rowan.

At least 19 recordsLinked to original sources
PubMed1990

Evaluation of a prototype for a reference platelet counter.

A semiautomated single channel aperture-impedance particle counter was developed as a prototype for a reference platelet count for assigning values to reference preparations used in automated blood cell counts. The instrument is equipped with sheath flow and an aperture orifice of 50 microns in diameter and 60 microns in length to eliminate non-axial flow and minimise coincidence errors. Use of fixed volume and red blood cell:platelet ratios obviate dilution errors. The counter was assessed in accordance with the International Committee for Standardization in Haematology protocol for evaluation of automated blood cell counters. The counter provided a high level of linearity and precision, accurate coincidence correction, controlled volume, stability and negligible carryover.

Erythrocyte Count↗
PubMed1990

Surrogate materials for calibration and control: the use of latex particles as calibrants for red cell volume measurements.

Latex particles, including BCR Certified Reference Material CRM 166a, have important applications for checking linearity and for calibrating aperture-impedance instruments used to determine red-cell volumes. Studies performed on Coulter Counters, e.g. the ZBi/C1000, ZM/C256 and Model S Plus IV, using a series of three different mono-sized latex particles have shown linearity but non-zero intercepts. This emphasizes the importance of calibrating instruments at more than one point. Latex particles also have an important role in calibration of red-cell volume measurements provided that a relative latex: red-cell shape factor has been assigned when the instrument is calibrated with fresh blood. Such relative shape factors are independent of latex particle size but need to be specific for instrument type and probably also for the orifice and diluent to be used. Nevertheless latex calibrants can serve an important role in standardizing red-cell volume measurements.

Calibration↗
PubMed1986

T4: T8-lymphocyte ratios in human bone marrow: the effect of sampling technique.

Marrow aspirate and trephine biopsy T4 : T8-lymphocyte ratios were compared with peripheral blood values. To do this, a new technique for harvesting marrow cells from trephine biopsies is described. Results show that blood and trephine ratios did not overlap. Marrow aspirate ratios were intermediate suggesting that peripheral blood contamination was causing aspirate T4 : T8 ratios to be falsely elevated.

Adolescent↗
PubMed1985

Cyclical neutropenia and T8 lymphocyte mediated stimulation of granulopoiesis.

A 33-year-old female with cyclical neutropenia and a reciprocally cycling T8 (suppressor/cytotoxic) lymphocytosis was investigated. T8 lymphocytes ranged between 1.4 and 5.6 X 10(9)/l and a significant proportion (50-75%) were preactivated (1a+). Fc gamma receptors were detected in only a minority (7-10%). Functional studies on the lymphocytes indicated that despite their phenotype, little natural killer and reduced suppressor activities were present. Anti-granulocyte antibodies were not detectable in the serum. Production of colony stimulating activity (CSA) was assessed in the patient and control subjects' lymphocytes. Using a methylcellulose marrow culture system, the CSA production by the patient's lymphocytes was markedly increased compared with the control. Monoclonal antibody cytotoxic experiments confirmed that the T8 lymphocytes were responsible. As peaks of circulating T8 lymphocytes were synchronous with granulopoietic activity in the marrow, the above findings may represent a homeostatic mechanism which is attempting to compensate for an underlying stem cell defect.

Adult↗
PubMed1979

Assessment of the Coag-a-Pet Dual Channel in the routine haemostatic laboratory.

The Coag-a-Pet Dual Channel is an instrument which automatically records coagulation test end-points utilizing a photo-optical clot detection system. The instrument and its operation are described in detail. The capability of the instrument to perform tests of oral anticoagulant control, basic coagulation profiles and one-stage factor assays is assessed. In terms of precision and accuracy, the instrument performs well in carrying out the one-stage prothrombin time, Thrombotest, activated partial thromboplastin time using an automated APTT reagent but not kaolin, and one-stage factor assays. The thrombin clotting time can not be measured on this instrument. The instrument is most suitable for batched repetitive tests, reducing observer error and improving laboratory efficiency.

Blood Coagulation Factors↗
PubMed1979

The Coulter Counter Model S Plus--the shape of things to come.

The Coulter Counter Model S Plus is a 12 parameter haematological analyser designed for service use in haematology laboratories. Eight parameters are standard in current routine haematological practice; the seven parameters generated by the Model S and a platelet count. The method of platelet counting is unique. The remaining parameters are new and comprise the platelet-crit, the mean platelet volume and size distribution measurements for both platelets and red cells. A description of the instrument is given including differences from the Model S. The new parameters are discussed in detail. Instrument precision is assessed in terms of linearity, reproducibility, drift, carry-over and protein build-up. The results of all are impressive. Instrument accuracy is assessed in detail; white cell count, red cell count, haemoglobin concentration and mean corpuscular volume being compared with those values measured by the Model S; the Model S Plus haematocrit is compared with the microhaematocrit and platelet counts with those from the Thrombocounter C/Thrombofuge system. All correlations are very satisfactory. Normal values are defined for the new parameters. Instrument design and function are assessed and reagent consumption quoted. Cell control reagents have been evaluated. A realistic hourly throughput for the Model S Plus is 70-80 samples.

Automation↗
PubMed1977

Evaluation of a semi-automated platelet-counting system.

Coulter Electronics Ltd have produced a semi-automated platelet-counting system. Platelet-rich plasma may be obtained either by tube sedimentation or by means of the Thrombo-fuge, the latter being an instrument designed to produce accelerated sedimentation. The instrument is linear over the entire range of platelet counts, and machine reproducibility is good. Comparison of machine-rated with visual counts satisfied statistical evaluation. The technique can be handled by one operator and platelet counts can be achieved at the rate of 30 per hour by both methods although individual counts on the Thrombo-fuge may be obtained in approximately one-quarter of the time required for tube sedimentation. The throughput using the Thrombo-fuge could certainly be doubled were two sample plates supplied. Few problems were encountered during the evaluation and most could be avoided by meticulous technique. Visual counts must be performed when the sample haematocrit is greater than 50%-Discrepant counts have been obtained in patients with white cell counts exceeding 50 X 10(9)/1 and in patients with giant platelets. ESR elevation for any reason does not lead to serious discrepancy in results. The incidence of platelet clumping due to the presence of platelet agglutinins and of microclot formation due to inadequate mixing is probably much higher than is commonly thought, and certainly peripheral blood film scrutiny should never be omitted in patients with low counts. Careful examination of peripheral blood films must be combined with instrument counting for some time lest further causes of discrepant counting emerge.

Blood Platelets↗
PubMed1977

Myelomatosis.

Explore the source record for details and available documents.

Acute Kidney Injury↗
PubMed1976

An assessment of the clinical usefulness of plasma ribonuclease assays.

The usefulness of plasma ribonuclease assays was studied in (i) patients with possible protein deficiency, (ii) patients with myelomatosis, (iii) patients with carcinoma of the breast. In each group, the major factor associated with elevation of plasma ribonuclease was impairment of renal function. The assay was therefore of little value in the assessment of patients with myelomatosis or carcinoma of the breast. However, in the patients with possible protein deficiency and normal renal function, an elevation of plasma ribonuclease is, in general, associated with a decrease in serum albumin, transferrin and cholinesterase. Plasma ribonuclease may therefore be a useful parameter in the assessment of protein nutritional status.

Acute Kidney Injury↗
PubMed1975

Neisseria catarrhalis septicaemia in acute lymphoblastic leukaemia.

A case of septicaemia due to Neisseria catarrhalis occurring in an immunosuppressed individual is described. The clinical syndrome closely resembled that of N. meningitidis septicaemia. The potential pathogenicity in the immunosuppressed patient, of organisms usually considered harmless is stressed.

Acute Disease↗
PubMed1974

A further application of the nitroblue tetrazolium test.

The nitroblue tetrazolium (N.B.T.) test was performed on patients in whom a differential diagnosis of pulmonary thromboembolism or lobar pneumonia existed. The mean N.B.T. score in healthy subjects was 6.4% (range 1%-15%). Patients with uncomplicated pulmonary thromboembolism showed a mean N.B.T. value of 7.5% (range 3%-12%). In patients with lobar pneumonia the mean N.B.T. score was 42.4% (range 21%-85%). These results suggest that the N.B.T. test is of value in the differential diagnosis of pulmonary thromboembolism and lobar pneumonia.

Adolescent↗