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Biomedical subjects

T C Pearson

Publications and source records attributed to T C Pearson.

At least 181 records · Page 10Linked to original sources
PubMed1984

A pilot study of epidoxorubicin (NSC 256942) in combination treatment of acute leukaemia and non-Hodgkin's lymphoma.

Epidoxorubicin (EDX) was administered to a group of 26 patients with acute leukaemia or lymphoma, replacing either daunorubicin or doxorubicin (DXR) as a component of multiple-chemotherapy regimens. In 10 patients with acute non-lymphocytic leukaemia treated at presentation, 5 complete and 4 partial remissions were obtained. All patients with lymphoma of different types responded at least partially: in a group of 14 cases, 8 in relapse and 6 at presentation, there were 10 complete and 4 partial remissions. It is of interest that such results were obtained in patients of high median age with dosages of EDX much lower than those employed for DXR.

Acute Disease↗
PubMed1983

Erythroid colony formation in primary proliferative polycythaemia, idiopathic erythrocytosis and secondary polycythaemia: sensitivity to erythropoietic stimulating factors.

This is a study of in vitro production of erythropoietic colonies from peripheral blood and bone marrow of normal subjects and patients with different polycythaemic conditions. Proliferative stimuli included: 1. Fetal calf serum (FCS) only. 2. FCS plus a source of erythropoietic-stimulating activity (ESA). 3. FCS + ESA + erythropoietin (Ep). It was found that normal subjects and patients with secondary polycythaemia (SP) exhibited full colony growth only in the presence of both ESA and Ep, while patients with primary proliferative polycythaemia (PPP) showed colony production with FCS alone, further enhanced in the presence of ESA and Ep. A group of patients with idiopathic erythrocytosis (IE), namely with an increase of red cell mass not accompanied by other signs of myeloproliferative disorder, and without underlying cause, showed a heterogeneous response to ESA which in some patients was significantly greater than in normal subjects or in SP patients. It appears therefore that sensitivity of erythropoietic colony formation to Ep and ESA may be helpful in differentiating among various forms of polycythaemia; this study also establishes the heterogenicity of the IE group.

Bloodletting↗
PubMed1983

Association of bacterial carbohydrate-specific cold agglutinin antibody production with immunization by group C, group B type III, and Streptococcus pneumoniae type XIV streptococcal vaccines.

Rabbits immunized with group B type III, group C, and Streptococcus pneumoniae type XIV streptococcal vaccines developed autoantibodies reactive with autologous and isologous erythrocytes and human O-positive erythrocytes at reduced temperatures. The cold agglutinin antibodies were present in both the immunoglobulin M (IgM) and IgG fractions of group C streptococcal antiserum and in the IgM fraction of group B type III and S. pneumoniae type XIV antisera. BALB/c, CF1, and local strains of mice immunized with group B type III and S. pneumoniae type XIV streptococcal vaccines also produced a cold agglutinin antibody reactive with rabbit and human erythrocytes. The cold agglutinin antibodies were reactive with saccharide compounds representative of the determinants present on the individual bacterial carbohydrate structures, individual vaccine preparations, and isolated polysaccharides. The group C antibodies in rabbits were reactive with sugar ligands in the following order: N-acetylgalactosamine greater than melibiose greater than lactose greater than galactose greater than glucose. Group B type III and S. pneumoniae type XIV cold agglutinin antibodies in rabbit antisera, however, displayed reactivities different from group C antibodies and from each other. Group B type III antibodies reacted with galactose greater than lactose greater than N-acetylgalactosamine greater than glucose greater than rhamnose; S. pneumoniae type XIV antibodies reacted with lactose greater than melibiose greater than galactose greater than glucose greater than N-acetylgalactosamine. The same relative ligand specificity was observed for the cold agglutinin antibodies in S. pneumoniae type XIV mouse antisera. The cold agglutinin antibodies in group B type III and S. pneumoniae type XIV antiserum reacted with erythrocytes at higher temperatures (up to 31 degrees C) than did group C antibodies (up to 14 degrees C). In addition, S. pneumoniae type XIV antibodies did not discriminate between I- or i-bearing human erythrocytes to a significant extent. The results obtained provide substantial evidence that autoreactive cold agglutinin antibodies produced by immunization with these vaccines represent subpopulations of bacterial carbohydrate-specific antibodies that cross-react with mammalian carbohydrate structures.

Agglutinins↗
PubMed1982

Trapped plasma in the microhematocrit.

The amount of trapped plasma in the microhematocrit red blood cell column of samples from 25 normal individuals and 102 patients was investigated. The mean value for the normal individuals was 1.53%, and the mean values for the samples from the patient groups ranged from 1.41% to 1.82%. These groups included patients with sickle cell disease, iron deficiency, and hereditary spherocytosis. There was an inverse correlation between trapped plasma and the MCH in the samples from patients with iron-deficiency (MCH less than or equal to 25.0 pg). These findings have relevance to the determination of the PCV and derived red blood cell indices.

Anemia, Hypochromic↗
PubMed1982

PCV measurement in the management of polycythaemic patients.

The PCV of samples from normal individuals and polycythaemic patients being treated by venesection were measured using the microhaematocrit corrected for trapped plasma, radio-isotope dilution, the Coulter 'S' and Coulter 'S Plus'. There was no significant difference between the two manual methods for either the normal individuals or the polycythaemic patients. The Coulter S and S Plus gave lower values for PCV compared with the corrected microhaematocrit, particularly for the polycythaemic patients. The underestimation of the PCV by the Coulter instruments for the polycythaemic group was significantly related to the MCH and MCV. The under-estimation was approximately 6.4% and 7.4% at an MCH of 20 pg by the Coulter S and S Plus respectively. These findings have relevance to the management of polycythaemia by venesection if the effectiveness of treatment is monitored by measuring the PCV by a Coulter instrument.

Blood Cell Count↗
PubMed1982

Platelet size: no correlation with migraine or monoamine oxidase activity.

A Coulter Model "S Plus" counter has been used to study platelets from 39 migrainous patients between attacks, six during attacks, eight with active cluster headache and 26 controls. None of the patient groups showed any abnormality in platelet size profile. There was no correlation between platelet monoamine oxidase activity and mean platelet volume in any of the groups.

Adult↗
PubMed1982

Exchange transfusion in life-threatening sickling crises.

Five patients are reported with sickle cell syndromes (HbSS, HbSC and HbSthal) in whom rapid exchange transfusion led to resolution of life-threatening infarctive crises. The technique appears to be of value in the management of severe complications of sickle cell syndromes.

Adult↗
PubMed1981

Cerebral blood flow and blood viscosity in patients with polycythaemia secondary to hypoxic lung disease.

Blood viscosity, cerebral blood flow (CBF) and cerebral oxygen carriage (CBF X arterial oxygen content) were measured in 12 patients with polycythaemia secondary to hypoxic lung disease. CBF and cerebral oxygen carriage were both significantly higher than in a comparative group of 20 patients with raised packed cell volumes and normal lung function. The patients with secondary polycythaemia then underwent venesection and their mean packed cell volume fell from 0.613 to 0.495. This led to a consistent reduction in blood viscosity, which fell by 44% at a low shear rate (0.67/s) and 33% at a high shear rate (0.91/s). CBF rose by 21% (p less than 0.01), but cerebral oxygen carriage did not significantly increase in the group as a whole. Four of the patients with secondary polycythaemia had complained of episodes of confusion before venesection, which improved considerably once the packed cell volume had been lowered. Headache was relieved in a further two patients and none of the subjects was adversely affected by venesection. It was not possible, however, to show a correlation between symptomatic improvement and an increase in cerebral oxygen carriage.

Aged↗
PubMed1981

Viscosity and iron deficiency in treated polycythaemia.

An in vitro study of the effect of red-cell changes due to iron deficiency on whole-blood viscosity has been made on samples from patients with polycythaemia treated by venesection. When the PCV of the samples was adjusted to a standard value of 0.45, whole-blood viscosity was unrelated to decreasing MCH. In contrast, when samples were adjusted to a standard Hb concentration of 14 g/dl, whole-blood viscosity rose exponentially with decreasing MCH. This increase in whole-blood viscosity was shown to be a function of the increasing PCV that accompanies the falling MCH at this standard Hb value. It is suggested that in polycythaemia not due to hypoxia, hyperviscosity can be satisfactorily corrected by venesection controlled by monitoring the PCV alone. Other consideration may apply in hypoxic polycythaemia and these are discussed.

Blood Viscosity↗
PubMed1980

Effect of high haematocrit on alertness.

Patients with high-normal or above-normal haematocrit were found to have impaired alertness when compared with a control group matched for age and occupation. On retesting the controls had improved alertness scores attributable to a practice effect; but the patients, when retested after reduction of haematocrit by venesection, had improved significantly more than the controls. Improvement in alertness correlated very well with the increase in cerebral blood flow which followed venesection. Levels of venous haematocrit that are generally accepted as normal may not necessarily be optimum.

Adult↗
PubMed1980

Management of relative polycythaemia: studies of cerebral blood flow and viscosity.

Cerebral blood flow has been shown to be reduced in a group of patients with high packed cell volume due to a reduced plasma volume (relative polycythaemia). 500 ml of intravenous Dextran 40 resulted in a significant fall in PCV and whole blood viscosity with a concomitant rise in cerebral blood flow (CBF). This effect, however, lasted less than 24 h. Oral fludrocortisone therapy (0.2 mg daily) resulted in no definite change in either PCV, viscosity or CBF. Venesection brought about a significant fall in PCV and whole blood viscosity with a significant rise in CBF. Of the methods used, venesection was the only practical long-term method of lowering PCV in this group of patients.

Aged↗
PubMed1980

Red cell mass, plasma volume and blood volume before and after venesection in relative polycythaemia.

Seven male patients with relative polycythaemia have had red cell mass, plasma volume and blood volume measurements made before and after venesection. The mean PCV prior to venesection was 0.522. Using a small volume (250 ml) serial venesection technique, in each the PCV was reduced to or below 0.45, the overall mean value being 0.431. Venesection resulted in a rise in plasma volume with no significant reduction in blood volume in six of the patients. Thus hypovolaemia does not occur in the majority of the patients. One patient did not increase his plasma volume on packed cell volume reduction. His blood volume fell by 15%. None of the patients developed any symptoms of hypovolaemia. To maintain the PCV at values less than 0.45, venesection was required on average once every 2 months. It is suggested that venesection of small volumes is an acceptable long-term method of lowering the PCV in patients with relative polycythaemia.

Aged↗
PubMed1980

Plasma and whole blood viscosity in treated primary polycythaemia.

Whole blood viscosity at a range of shear rates (230--0.77 s-1) and plasma viscosity have been measured in 39 patients with treated primary polycythaemia (idiopathic erythrocytosis and primary proliferative polycythaemia) and 30 age-matched normal individuals. There was a wider range of plasma viscosity and whole blood viscosity values at the same haematocrit (0.46), particularly at the lower shear rates, in the 'polycythaemic' group than the normal group. Hypochromic microcytic red cell changes present in 14 patients in the 'polycythaemic' group did not have any noticeable influence on whole blood viscosity at a given haematocrit value, since plasma protein factors override any possible effect of these red cell changes. The range of observed whole blood viscosity results in the 'polycythaemic' patients at the same haematocrit (0.46) was equivalent to the effect on whole blood viscosity of a rise in haematocrit from 0.41 to 0.51. Since there is such a range of whole blood viscosity at the same haematocrit, the haematocrit alone does not necessarily give a precise assessment of the viscosity of a whole blood sample. Since there is evidence from other publications that blood flow in vitro may be critically influenced by whole blood viscosity, this lack of precision should be considered when treating patients at risk of vascular occlusive episodes.

Adult↗
PubMed1980

Viscosity, cerebral blood flow and haematocrit in patients with paraproteinaemia.

It has been suggested that blood viscosity is involved in the control of cerebral blood flow (CBF) (Thomas et al. 1977a, b, Humphrey et al. 1979). CBF, using the intravenous Xenon133 technique, blood viscosity and haematocrit were measured in 21 patients with elevated viscosity due to paraproteinaemia and found to be the same as in normal subjects. However, the paraproteinaemic patients were anaemic with a mean haematocrit of 0.342. This degree of anaemia would normally be associated with a high CBF. The paraproteinaemic patients were then compared with a group of 10 anaemic patients with matched haematocrits but without paraprotein bands. The whole blood and plasma viscosities were significantly higher in the paraproteinaemic patients and the CBF was significantly lower. The haematocrit, and therefore oxygen carriage, was similar in the two groups. It is likely that in the anaemia of paraproteinaemia the expected increase in CBF did not occur because of the limiting factor of increased viscosity. This suggests that in this instance viscosity rather than oxygen carriage is a major determinant in the control of CBF. This is further emphasized by the better correlation between CBF and blood viscosity than between CBF and haematocrit. It seems likely that viscosity and oxygen carriage are independent variables in the control of CBF.

Aged↗
PubMed1980

Cerebral blood flow, haematocrit and viscosity in subjects with a high oxygen affinity haemoglobin variant.

The cerebral blood flow is low in primary polycythaemia, and it has been suggested that this is due to the increase in viscosity which accompanies the elevated haematocrit. In the present study cerebral blood flow has been measured by a non-invasive 133Xenon technique in six subjects with an elevated haematocrit secondary to a haemoglobin variant with increased oxygen affinity. Flow was significantly higher than normal and 81% higher than in 11 subjects of comparable age, matched for haematocrit and viscosity, but without the haemoglobin variant. In patients with this unusual type of polycythaemia, cerebral blood flow is high despite the elevated blood viscosity and the implications of these results are discussed.

Adult↗