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Biomedical subjects

S M Lewis

Publications and source records attributed to S M Lewis.

At least 235 records · Page 13Linked to original sources
PubMed1976

The relationship between total red cell volume, plasma volume and venous haematocrit.

Total red cell volume (TRCV) and plasma volume (PV) have been measured in 130 cases including 65 polycythaemic patients and 65 patients with a wide variety of disorders. Patients with gross splenomegaly were excluded from the study. The regression of TRCV on venous haematocrit (VHct) was found to be curvilinear, a single exponential function providing a good approximation ( r=0.92, P less than 0.001). No significant difference was found between the mean PVs of the polycythaemic and control groups (40.97 and 42.94 ml/kg respectively) although a slight but highly significant negative correlation was observed between PV and VHct (r = 0.47, P less than 0.001). This most marked for patients with VHcts below 0.30, for whom a separate plot yielded a correlation coefficient of 0.75. Total blood volume (TBV) and VHct were found to be positively correlated (r = 0.57, P less than 0.001) as would be expected from the TRCV and PV data. The significance of these findings is discussed.

Blood Volume↗
PubMed1976

Intercellular contacts between erythroid precursors in the bone marrow in dyserythropoiesis.

The ultrastructure of the cellular interfaces between erythroid precursors has been studied in both congenital and acquired dyserythropoiesis. The types of cell-to-cell contacts found included highly convoluated interdigitating septate-like junctions as well as apparent confluence of the cellular membranes of adjacent erythroid cells. Such findings are not characteristic of the intercellular relationships found in the normal erythroblastic islands. The erythroid plasma membrane modifications are possibly related to the changes in the plasma membranes of erythroid cells known to occur in dyserythropoiesis and their presence may well contribute to the ineffective erythropoiesis with intramedullary cell destruction which characterizes many dyserythropoietic states.

Bone Marrow↗
PubMed1976

Quantitative studies of splenic erythropoiesis in polycythaemia vera and myelofibrosis.

A quantitative scanning method employing cyclotron-produced 52Fe has been developed to assess splenic erythropoiesis in patients with myeloproliferative disorders. In 12 patients with myelofibrosis splenic uptake of 52Fe was from 5.0% to 48% of the injected dose. Although a single patient with classical polycythaemia vera had a minor uptake of 2.8% of six other patients with this diagnosis showed no concentration of isotope in the splenic area. The fraction of 52Fe in the spleen of four patients with 'transitional' myeloproliferative disorders characterized by a high red cell mass, hypercellular bone marrow and a leucoerythroblastic blood film varied from 5% to 41%. No clear relationship was noted between the degree of splenic erythropoiesis as defined by this technique and the level of haemoglobin, the degree of splenomegaly, the effectiveness of erythropoiesis of traditional 59Fe surface counting. If splenectomy is considered in patients with myelofibrosis splenic 52Fe quantitation will provide more precise data on the contribution of splenic erythropoiesis than 59Fe surface counting alone.

Erythropoiesis↗
PubMed1976

Purified azure B as a reticulocyte stain.

A comparison has been made between reticulocyte preparations stained with purified azure B and with several commerically available batches of brilliant cresyl blue and new methylene blue. Marked variations were observed in the composition and staining performances of the various batches of the two commerically available dyes. Although there were no significant differences in reticulocyte counts obtained with these two dyes, varying amounts of an extraneous, particulate dye deposit were present in these preparations, making accuracte counting both tedious and timeconsuming. Purified azure B, on the other hand, gave reproducibly stained, deposit-free preparations. Reticulocyte counts obtained from azure B preparations correlated almost exactly with those determined using new methylene blue. Purified azure B is therefore recommended as a convenient reticulocyte stain for routine use.

Azure Stains↗
PubMed1976

Rate of clearance by the spleen of heat-damaged erythrocytes.

The rate of uptake in the spleen of heat-damaged red blood cells labelled with 99mTc has been measured by radioisotope scanning in 38 patients. The values obtained for the half-clearance time into the spleen using this method have been compared with the values obtained simultaneously by blood sampling for the rate of loss of radioactivity from the circulation. It was found that the uptake into the spleen was approximately three times faster than the measured rate of loss of radioactivity from the blood. The reasons for this are discussed and it is suggested that the scanning technique is more reliable as a measure of this aspect of splenic function.

Cell Movement↗
PubMed1975

Quantitative measurement of splenic and hepatic red-cell destruction.

A method has been developed by means of which independent measurement can be made of the amount of red-cell destruction occurring in the spleen and the liver. The technique involves a standard red-cell survival study and surface-counting measurements together with quantitative scanning of the spleen and liver with 113mIn colloid in order to calibrate the surface counter. The rate of destruction in each organ is obtained by fitting the measured uptake curve for the organ to a theoretical uptake curve by computer. In addition, if whole body counting is also performed, the amount of red-cell destruction occurring in the rest of the reticuloendothelial system may be deduced. Results are given for measurements on a series of 11 patients.

Chromium Radioisotopes↗
PubMed1975

The use of an image analysing computer for the quantitation of red cell morphological characteristics.

Measurements of integrated optical density and projected area of red cells have been made on Romanowsky-stained blood films from 25 subjects using an image analysing computer. Close correlation was observed between mean cell projected area and MCV and between mean cell integrated optical density and MCH. Mean values for the quotient of cell integrated density/cell projected area (mean cell colour density) correlated with MCHC. Varieties of cell area and colour density correlated subjectively with anisocytosis and anisochromasia, and histograms of these parameters demonstrated dual populations. The clinical application of these findings is discussed.

Anemia↗
PubMed1975

The ultrastructure of dyserythropoiesis in aplastic anaemia.

Electron microscopy of erythropoiesis in aplastic anaemia has demonstrated some unique features of dyserythropoiesis at the ultrastructural level, which contribute to understanding of the morphological features which are seen in the light microscope. The findings provide further evidence for the presence of qualitative defects in erythropoiesis in aplastic conditions. The alterations seen included bi- and multinucleated cells, intercellular bridges containing microtubules, internuclear chromatin bridges, irregular nuclear shapes, juxta-nuclear and peripheral cisternal structures, ringed sideroblasts, a diversity of intranuclear inclusions, nuclear clefts in both eu- and heterochromatin, and a variety of anomalies of the nuclear membrane. The significance of the occurrence of these anomalies in aplastic anaemia is considered and the role of the nuclear membrane and of endoplasmic reticulum in the pathogenesis of aplastic anaemia is discussed.

Adult↗
PubMed1975

A transmission electron microscope study of the effects of ion etching on cells.

The effects of ion etching on blood cells have previously been studied by scanning electron microscopy. This present study by transmission electron microscopy was undertaken to evaluate the effects of the etching process on the cells. Critical point dried preparations were made, etched and subsequently processed and embedded in Araldite. Examination of thin sections of erythrocytes revealed disintegration of the plasma membrane; the residual membrane destruction products formed the tips of cones produced by long etching times. The effect of etching varied in erythrocytes in the same preparation. Nucleated cells showed a similar disintegration of the plasma membrane, but membranes of mitochondria, granules, vesicles and vacuoles did not exhibit effects of etching comparable to those of the plasma membranes. After treatment with a number of different fixatives, erythrocytes on carbon-coated copper grids were also etched and examined directly in a high voltage electron microscope at 1 MV. The effects were comparable to those seen in thin sections. To study the etch rates of biological materials, the resonant frequencies of quartz crystals were measured after application of thin films of albumen and cholesterol and again after these had been etched. the ratio of the frequency changes indicated that the etch rate of albumen was approximately 2-5 times that of cholesterol. The results are discussed in the light of theories of the mechanisms involved in ion etching.

Cell Membrane↗
PubMed1975

An evaluation of some commerical Romanowsky stains.

The staining properties of 43 commerical Romanowsky-type stains have been studied. Considerable differences in the appearance of stained blood films were observed with different batches of these stains, the staining of red cells being particularly variable. Attempts have been made to correlate staining patterns with stain composition as revealed by thin-layer chromatography and sulphated ash analyses. In this way it has been possible to define some essential requirements for satisfactory staining.

Azure Stains↗
PubMed1975

Awake baboon's ventilatory response to venous and inhaled CO2 loading.

Steady-state ventilatory responses to CO2 in trained awake baboons were studied to determine the response to a venous CO2 load. CO2 was loaded either directly into the venous blood through an arteriovenous shunt or by addition to the inhaled air. The two modes of loading were adjusted to produce the same increase in minute volume. Minute volume, tidal volume respiratory frequency, end-tidal PCO2, PaCO2, and pHa were measured. PaCO2 and PETCO2 increased the same amount during the two modes of CO2 loading; thus, the response to changes in arterial PCO2, deltaVE/deltaPaCO2, was the same. I conclude that the ventilatory response to venous CO2 loading occurs only through the change in mean arterial PCO2 and thus it is unlikely that there are any important venous CO2 receptors.

Animals↗
PubMed1975

A procedure for assaying commercial samples of eosin.

A simple, rapid and inexpensive assay method for the colored components of commercial samples of eosin is described. Samples are dissolved in dilute aqueous ammonia and absorbance measurements made at wavelengths of 492 nm, 512 nm, and 518 nm. The concentrations of fluorescein, tribomofluorescein and eosin are derived by solution of simulataneous equations in three unknowns. The validity of the method has been confirmed by recovery experiments. Mean recoveries of fluorescein, tribromofluorescein and eosin were 99.1%, 100.2% and 98.8% respectively. Seventeen commercial samples have been assayed by this procedure. Concentrations of fluorescein, tribromofluorescein and eosin ranged from 0.00%-0.82%, 4.34%-29.92% and 44.89%-82.82% respectively. The sodium concentrations of the same samples were measured by atomic absorption spectrophotometry and found to range from 0.10% to 6.13%. The presence of free halide (Br-, Cl-, or both) was demonstrated. These observations, together with color variations in the samples, indicate that in commercial products eosin is in the form of both the free acid and sodium salt. Volatile matter accounted for 1.68%-16.11% of the samples.

Chromatography, Thin Layer↗
PubMed1975

Metal contaminants in commercial thiazine dyes.

The iron, potassium, sodium and zinc content of commercial samples of the thiazine dyes azure A (C.I. 52005), azure B (C.I. 52010), azure C (C.I. 52002), methylene blue (C.I. 52015), new methylene blue (C.I. 52030), polychrome methylene blue, thionine (C.I. 52000) and toluidine blue (C.I. 52040) have been determined by atomic absorption spectrophotometry. The metal concentration varied widely in the 38 samples examined--iron, potassium, sodium and zinc together comprised between 0.02% and 25.35% of individual samples.

Chromatography, Ion Exchange↗
PubMed1975

The purification of methylene blue and azure B by solvent extraction and crystallization.

Detailed schemes are described for the preparation of purified methylene blue and azure B from commercial samples of methylene blue. Purified methylene blue is obtained by extracting a solution of the commercial product in an aqueous buffer (pH 9.5) with carbon tetrachloride. Methylene blue remains in the aqueous layer but contaminating dyes pass into the carbon tetrachloride. Metal salt contaminants are removed when the dye is crystallized by the addition of hydrochloric acid at a final concentration of 0.25 N. Purified azure B is obtained by extracting a solution of commercial methylene blue in dilute aqueous sodium hydroxide (pH 11-11.5) with carbon tetrachloride. In this pH range, methylene blue is unstable and yields azure B. The latter passes into the carbon tetrachloride layer as it is formed. Metal salt contaminants remain in the aqueous layer. A concentrated solution oa azure B is obtained by extracting the carbon tetrachloride layer with 4.5 X 10(-4)N hydrobromic acid. The dye is then crystallized by increasing the hydrobromic acid concentration to 0.23 N. Thin-layer chromatography of the purified dyes shows that contamination with related thiazine dyes is absent or negligible. Ash analyses reveal that metal salt contamination is also negligible (sulphated ash less than 0.2%).

Azure Stains↗