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Biomedical subjects

S M Lewis

Publications and source records attributed to S M Lewis.

At least 217 records · Page 12Linked to original sources
PubMed1978

Splenic red cell pooling: a diagnostic feature in polycythaemia.

Total red cell volumes and splenic red cell pools were measured in 31 patients with polycythaemia. 22 had polycythaemia vera (PV), 12 of whom had clinically detectable splenomegaly, and nine patients had secondary polycythaemia (PS). The mean red cell pool was 192.8 ml (SD 126.6) in PV (all cases), and 130.9 ml (SD 28.4 ml) in PV without splenomegaly; it was 61.1 ml (SD 8.3 ml) in PS. When expressed relative to spleen size (in cm), differences were even more striking: PV (all cases)--mean 13.7 ml/cm (SD 4.3); PV without splenomegaly--mean 12.7 ml/cm (SD 2.2); PS--mean 6.6 ml/cm (SD 1.2). Measurement of splenic red cell pool thus appears to be a valuable diagnostic tool for distinguishing between PV and PS. The findings point to the presence in PV of a splenic structural abnormality which is not simply an effect of the increased circulating red cell mass.

Adult↗
PubMed1978

Localization and role of calcium in the erythrocyte coat: effects of enzymes and storage.

The effects of various treatments on erythrocyte shape, surface, cell coat and calcium binding sites have been investigated by means of high voltage electron microscopy (HVM), scanning electron microscopy (SEM) and conventional electron microscopy (TEM). Papain caused the formation of small blisters within the cellular surface as well as crenation and 'budding' of the erythrocytes. After neuraminidase treatment, long filaments were observed to radiate from the surface of the erythrocyte. The other enzymes investigated, RNA'se DNA'se, phospholipase, protease and trypsin, produced no demonstrable effect on the cellular structure, nor (with the possible exception of trypsin) on the cell coat as seen by subsequent staining with ruthenium red. Putative calcium binding sites on and in the erythrocyte membrane were demonstrated. Following incubation with radioactive calcium, activity was found in the erythrocyte membranes. Calcium binding could be reduced by prior treatment of the erythrocyte with EDTA, neuraminidase, and to a lesser extent, by papain and trypsin. Other enzymes had no demonstrable effect. Stored erythrocytes showed a progressive diminution in calcium binding over a period of up to 4 weeks.

Binding Sites↗
PubMed1978

Polycythaemia vera-transformation to myelofibrosis and subsequent reversal.

A woman aged 67 who developed polycythaemia vera 21 years ago has been seen regularly since the diagnosis was first made. She was treated initially with pyrimethamine and then for 10 years by repeated venesections. After a 4 year period when her myeloproliferative disease was considered to be transitional a complete transformation to myelofibrosis occurred. She was treated by splenic irradiation and later with alkylating agents in an attempt to give her symptomatic relief from massive splenomegaly. Repeated and massive haemorrhage from gastro-oesophageal varices was treated initially by percutaneous transhepatic sclerosis of the gastro-oesophageal collateral vessels. A subsequent dacron mesocaval jump graft operation was successful in preventing further haematemesis and melaena. During the last year transformation back to polycythaemia vera has occurred. The evolution of her myeloproliferative disease has been fully documented by detailed blood counting, bone marrow aspirates and trephine biopsies, blood volume studies and other radioisotope investigations including the quantitation of functional erythropoietic tissue with 52Fe.

Aged↗
PubMed1978

Staining properties and stability of a standardised Romanowsky stain.

An evaluation of the standardised Romanowsky stain of Marshall et al. has been made in a routine haematology laboratory. It was noted that this stain had several advantages over the May-Grünwald Giemsa stain used in most British laboratories. These advantages include ease and speed of preparation, a shorter staining time, and reproducibility of results. These results are described in detail. The stability of the stock stain solution and of the 'working' stain (stock + buffer) has been studied by, respectively, thin-layer chromatography and visible spectroscopy. No change was detected in the composition of the stock solution at ambient temperature over a period of six months. Stability was unaffected by the composition of the container (polyethylene, PyrexTM, or soda-glass) or by daylight. The 'working' solution was stable for 3 hours. Thereafter a precipitate is formed, consisting of thiazine dyes and eosin in a molar ratio of approximately 2:1.

Chromatography, Thin Layer↗
PubMed1978

An analysis of blood specimen container leakage.

Procedures have been designed to test specimen containers for leakage, using blood and aqueous fluorescein solution as indicators. They have been used in a trial evaluation of a number of commercially available containers intended for medical specimens. Glass bijou bottles, evacuated container systems, and several types of plastic container showed no significant leakage rate with either blood or aqueous solution when they were tested at room temperature, but a large proportion of the plastic containers leaked after being subjected to -20 degrees. C. These would thus be suitable and satisfactory for blood count specimens but not for specimens of serum and other body fluids, which are usually stored frozen. With all types of container tested there was spontaneous discharge of contents (blood or aqueous solution) on opening in a proportion of them; thus no container at present available seems to be entirely free from hazard.

Blood Preservation↗
PubMed1978

Continuous distributions of specific ventilation recovered from inert gas washout.

We describe a new technique for recovering continuous distributions of ventilation (V) as a function of tidal ventilation/volume ratio (V/V0) from the nitrogen washout. The analysis yields a continuous distribution of V as a function of V/V0 represented as fractional ventilations of 50 compartments plus dead space. The procedure was verified by recovering known distributions from data to which noise had been added. Using an apparatus to control the subject's tidal volume and FRC, mixed expired N2 data gave the following results: a) the distributions of young, normal subjects were narrow and unimodal with a mean ln standard deviation of 0.56 plus or minus 0.13; b) those of subjects over age 40 were broader (ln SD 0.86 plus or minus 0.19) with more poorly ventilated units; c) patients with pulmonary disease of all descriptions showed enlarged dead space; d) patients with cystic fibrosis showed multimodal distributions with the bulk of the ventilation going to overventilated units; and e) patients with obstructive lung diseases fell into several classes, three of which are illustrated. These results suggest that our approach is well suited for clinical investigation.

Adult↗
PubMed1978

Emptying patterns of the lung studied by multiple-breath N2 washout.

Changes in the nitrogen concentration seen during the single-breath nitrogen washout reflect changes in relative flow (V) from units with differing ventilation/volume ratios (V/V0). The multiple-breath washout provides sufficient data for the V for units with varying V/V0 to be plotted as a function of the volume expired. Flow from the dead space may also be determined. In young normals the emptying patterns are narrow and unimodal throughout the alveolar plateau with little or no flow from the dead space at the end of the breath. Older normals show more flow from the dead space, particularly toward the end of the breath, and some show a high V/V0 mode early in the breath. Patients with obstructive lung disease have a high flow from the dead space which is present throughout the breath. A well ventilated mode at the end of the breath is seen in some obstructed subjects. Patients with cystic fibrosis showed a poorly ventilated mode appearing at the end of the breath as well as a very high dead space.

Adult↗
PubMed1978

Ultrastructural study of normal and leukaemic leucocyte processes.

Cellular processes of leucocytes from both normal and leukaemic subjects were studied at the ultrastructural level. By high voltage transmission electron microscopy without a metal coating, more surface features could be seen in the cells than were observed by either scanning electron microscopy or conventional transmission electron microscopy. The technique was shown to be especially useful as it allows direct visualisation of the cell surface structure at high resolution without artefact-inducing preparative processes. Demonstrating receptor sites with this technique opens up the possibility of studying lymphocyte microvilli in greater detail.

Binding Sites↗
PubMed1978

Standardization of Romanowsky stains. The relationship between stain composition and performance.

A panel of 17 eminent haematologists has assessed the performance of 5 Romanowsky stains prepared from pure component dyes, comparing the suitability and acceptability of these stains for the preparation of routine blood and bone-marrow films. It was found that the results obtained using the stain described by Marshall et al (1975) were comparable to those obtained using a modification of the stain described by Wittekind et al (1976). The performance of the 3 other stains was less acceptable. Variations in stain formulation have been correlated with stain performance.

Blood Cells↗
PubMed1977

Splenic red cell pooling in hairy cell leukaemia.

The splenic red cell volume has been measured directly by an isotope method with quantitative scanning in 10 patients with leukaemic reticuloendotheliosis (hairy cell leukaemia). The volume ranged between 211 and 726 ml (mean 410 ml, SD 158) and this constituted 15--48% (mean 28.1%, SD 9.5) of the total circulating red cell volume. This is an exceptionally large pool when compared with that found in myeloproliferative and lymphoproliferative disorders with the same degree of splenomegaly. It is consistent with the histological features which show marked red cell accumulation in the splenic cord areas. The red cell pooling in the spleen thus appears to be a significant factor in the anaemia and there was fairly good correlation between the percentage of improvement in the anaemia and the percentage of red cell volume contained in the spleen. By direct measurement of the splenic red cell pool, it is possible to predict the extent to which splenectomy will benefit the anaemia and this may also provide an indirect measure of the extent of bone marrow dysfunction in the causation of the anaemia.

Adult↗
PubMed1977

Erythroid hypoplasia in myelofibrosis: a feature associated with blastic transformation.

Four cases of myelofibrosis have shown a pattern which is usually found only where there is erythroid hypoplasia and in none of these was there evidence of extramedullary erythropoiesis. Three of these cases terminated in a blastic phase. The findings suggest that the occurrence of erythroid hypoplasia in myelofibrosis may be associated with blastic transformation--whether as a predisposing factor or as a secondary event is still speculative. This phenomenon is discussed in relation to the natural history of myelofibrosis.

Bone Marrow↗
PubMed1977

Haemocytometry by laser-beam optics: evaluation of the Hemac 630L.

Hemac is an automated blood counting system which is based on production of impulses from light scattered and diffracted by cells flowing past a laser beam. The pulses are processed electronically for cell counts and packed cell volume; haemoblobin is measured as cyanmethaemoglobin; absolute values are computed. On evaluation the precision was of the order of 2% for Hb and RBC, 2-8% for PVC, and 3% for WBC. When compared with other methods in the routine laboratory, PCV and absolute values gave divergent results, but PCV was found to correlate well with microhaematocrit corrected for trapped plasma. This suggests that Hemac may more closely reflect true values of PCV, MCV, and MCHC than other routine methods. Whether this "accuracy" is necessarily an advantage must be considered ietation of the blood count data, especially MCV, are discussed.

Animals↗
PubMed1977

The combined use of iron 52 and its contaminant iron 55 in studies of the bone marrow.

A liquid scintillation counting technique has been used to measure 55Fe incorporation into red blood cells with counting efficiencies of the order of 10% for 0.1 ml whole blood. Measurements have been carried out over a period of two weeks following the intravenous administration of the shortlived cyclotron produced 52Fe which contains 55Fe (half-life 2.6 years) as contaminant. 52Fe, with its short half-life of 8.2 hours and suitable gamma-ray emissions, is the isotope of choice for bone marrow imaging and short term ferrokinetic studies such as plasma clearance and early organ uptake of iron. However, long term iron utilization cannot be measured with this radionuclide alone. By exploiting the presence of 55Fe this limitation has now been overcome.

Adult↗
PubMed1976

The morphological classification of red cells using an image analysing computer.

Image analysis provides a potential method for automation in the examination of blood films. In order to assess the applicability of this technique to red cell morphology, a scheme has been defined for the classification of red cells into six categories, namely, round cells, elongated cells, tear drop poikilocytes, helmet cells, irregular cells and spherocytes. A study was carried out to determine the consistency which observers classified red cells according to this scheme. Measurements of area, perimeter, maximum diameter and integrated optical denisty of fixed, Romanowsky-stained red cells were made using an image analysing computer. A multivariate classifier based on parameters derived from these measurements, namely cell area and the quotients of integrated density over area, area over the square of perimeter and perimeter over maximum diameter was also used to classify red cells into the above categories. It was found that the inherent error of the machine-based classifier was of the same order as the degree of inconsistency encoutered between trained observers. The significance of these findings is discussed.

Computers↗