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Biomedical subjects

T C Pearson

Publications and source records attributed to T C Pearson.

At least 163 records · Page 9Linked to original sources
PubMed1986

Intermittent hypoxia in patients with unexplained polycythaemia.

The aetiology of polycythaemia is unclear in up to 30% of patients. Twenty patients with unexplained polycythaemia were investigated to see whether they had an intermittent hypoxic stimulus to erythropoiesis that was undetected by conventional investigations for hypoxic secondary polycythaemia. Overnight polygraphic sleep studies showed that five patients had prolonged nocturnal hypoxaemia. Their arterial oxygen saturation was below 92%, the level at which appreciable hypoxic stimulation of erythropoiesis occurs, for 26-68% of the time for which they were studied. Considerable evidence is accumulating that intermittent hypoxia is a potent stimulus to erythropoiesis, and clinicians should consider the possibility of nocturnal hypoxia in patients with unexplained polycythaemia. Appropriate investigation will lead to the correct diagnosis of polycythaemia secondary to hypoxia in some cases previously regarded as idiopathic, and treatment may then be planned accordingly.

Adult↗
PubMed1986

Determination of serum immunoreactive erythropoietin in the investigation of erythrocytosis.

We assessed the diagnostic value of determinations of serum levels of immunoreactive erythropoietin in 90 patients referred for the investigation of a raised packed red-cell volume (hematocrit) and possible erythrocytosis (a red-cell volume greater than that predicted by weight, body-surface area, or both). The mean values for erythropoietin were 16 mIU per milliliter (range, 8 to 22) in patients with polycythemia rubra vera (n = 24), 30 mIU per milliliter (range, 14 to 123) in patients with secondary erythrocytosis (n = 12), 27 mIU per milliliter (range, 13 to greater than 400) in patients with erythrocytosis of unknown origin (n = 19), and 25 mIU per milliliter (range, 18 to 35) in normal controls (n = 25). The values in the patients with polycythemia rubra vera were lower than those in the other three groups (P less than 0.01, P less than 0.05, and P less than 0.0001, respectively). In subjects with an increased packed red-cell volume but without erythrocytosis (n = 35), the levels of serum erythropoietin were the same as those in normal controls. Among patients with erythrocytosis with an unknown cause, abnormally high serum erythropoietin levels were found in 3 of 19 subjects, and in 1 of these 3 the abnormality was intermittent. Thus, measurement of serum erythropoietin in a single sample may be misleading and may not have high discriminatory value in distinguishing between polycythemia rubra vera and secondary erythrocytosis. This assay is useful in identifying patients with secondary erythrocytosis who have inappropriate erythropoietin secretion.

Adult↗
PubMed1986

Primary thrombocythaemia treated with busulphan.

Thirty-seven patients with primary thrombocythaemia (PT) treated with busulphan have been followed for periods up to 25 years. Reduction of the platelet count to less than 400 X 10(9)/l resolved vascular occlusive symptoms, but haemorrhagic symptoms often remained unaltered. Cox regression analysis indicated that there were only two prognostically important presenting features; age had a strong inverse correlation with survival and vascular occlusive symptoms correlated with a better survival. Median duration of survival on treatment was 9 X 8 years. The number of deaths was 2 X 1 times that of a comparable control group, with deaths from myelofibrosis markedly increased. Deaths from thrombosis and malignant diseases, including leukaemia, were not significantly different from the number expected, which emphasizes the efficacy and the relative safety of busulphan for the long-term treatment of PT. Progression of PT into myelofibrosis occurred in 24% of cases and 9% became polycythaemic. Two additional cases of "thrombocythaemia' with a Philadelphia chromosome (and no overt evidence of chronic granulocytic leukaemia) are also presented.

Adult↗
PubMed1986

Whole blood viscosity in polycythaemia: the effect of iron deficiency at a range of haemoglobin and packed cell volumes.

The effect of iron deficient red cells changes (MCH range 20.0-32.6 pg) on whole blood viscosity (WBV) at high and low shear rates (94.5 and 0.51 s-1), has been assessed at a wide range of standardized PCV (0.30-0.65) and standardized Hb values (10.0-22.0 g/dl). Particular attention was given to the precision of PCV measurement. At all PCV values there was no correlation between MCH and WBV, whereas at all Hb values there was a significant negative correlation between MCH and WBV. If the treatment of polycythaemia is by venesection, iron deficient red cell changes occur frequently. These changes are unimportant if control of the WBV is the objective of treatment, as long as the PCV is accurately measured. Alternatively, in the secondary polycythaemias, where oxygen saturation is reduced, the induction of iron deficient red cell changes could be regarded as disadvantageous since at a standard PCV of 0.50 the Hb and hence oxygen carrying capacity is reduced by approximately 11% between MCH values of 30 and 20 pg.

Blood Viscosity↗
PubMed1986

Screening tests for Sezary cells in cutaneous T-cell lymphomas.

Blood samples from normal individuals (n = 7), from patients with cutaneous T-cell lymphomas (Sezary syndrome = 7; mycosis fungoides = 18) and from patients with chronic benign skin disease (n = 8) were examined for the presence of Sezary cells. The samples were analysed using a Coulter model S Plus IV with a three Cell Population upgrade, and a Becton Dickinson FACS analyser; and the results were compared with those obtained from morphological examination of peripheral blood films. Using the FACS analyser a population of aneuploid cells was only identified in two out of eight patients with confirmed circulating Sezary cells. This was in contrast to the results from the Coulter S Plus IV which detected an abnormality in six out of the eight samples with confirmed circulating Sezary cells. These results indicate that leukocyte volume analysis is a useful, additional screening tool for the identification of Sezary cells.

Flow Cytometry↗
PubMed1986

Shunts for portal hypertension: MR and angiography for determination of patency.

Twenty-eight patients with selective and nonselective shunts for portal hypertension were evaluated using magnetic resonance (MR) imaging. Angiographic correlation was obtained in 25 patients. MR imaging enabled the detection of a patent shunt by visualizing the "flow void" phenomenon in 21 patients. Two patients had thrombosed shunts. In these 23 patients, there was no discrepancy between the findings from MR imaging and those from angiography. In the remaining five patients, there was an area of artifact in which no signal was noted, and the shunt could not be evaluated. In all five patients who had this artifact, steel coils were noted in the area of the phenomenon. Thus, MR imaging seems to be an accurate method for detecting shunt patency in all patients with shunts except those who have had prior embolization with steel coils.

Angiography↗
PubMed1985

Intravenous and oral demethoxydaunorubicin (NSC 256-439) in the treatment of acute leukemia and lymphoma: a pilot study.

Demethoxydaunorubicin (DMDR), a new anthracycline available both for intravenous and oral administration, was given in 14 cases of leukaemia, non-Hodgkin's lymphoma (NHL) and multiple myeloma (MM) replacing either daunorubicin (DNR) or doxorubicin (DOX) in conventional chemotherapy regimes. In acute leukaemia (6 myeloblastic and 1 common lymphoblastic) there were 5 complete (CR) and 2 partial (PR) remissions; one patient, previously brought into remission with a regime including i.v. DMDR was thereafter maintained in CR with oral DMDR. Among the patients treated with the oral DMDR, 2 NHL cases were treated; 1 patient had a sustained remission of 12 months so far, with DMDR alone; another patient had a CR with a combined regime. In MM, one patient with very advanced disease treated with i.v. DMDR/CHOP did not respond, but three cases treated with oral DMDR plus other drugs showed a partial remission. Toxic effects were limited to brief episodes of nausea and vomiting in a few i.v. treated patients; a prolonged bone marrow depression was observed in one case only. No cardiotoxic effect was recorded.

Acute Disease↗
PubMed1985

Acute biphenotypic leukaemia (myeloid and null-ALL type) supervening in a myelodysplastic syndrome.

An acute leukaemia was seen in a 72-year-old patient with a myelodysplastic syndrome (MDS) of 14 months duration, who had been treated only with steroids. The morphological appearance of the blast cells suggested a poorly differentiated cell type. Surface marker analysis, including double staining studies, showed the coexistence of a population of null acute lymphoblastic leukaemia (ALL) blast cells together with acute myeloid leukaemia type cells. No chromosomal alterations were detected. The change from a chronic MDS to an acute leukaemia of mixed (myeloid and null ALL) type suggests either transformation of a pre-existing abnormal clone or de novo appearance of two separate leukaemic clones.

Aged↗
PubMed1985

Treatment of primary proliferative polycythaemia by venesection and low dose busulphan: retrospective study from one centre.

Sixty-five patients with primary proliferative polycythaemia (polycythaemia rubra vera) were followed during the period 1962-83 and analysed retrospectively. Primary control of PCV was by venesection only with low dose busulphan solely as required to keep the platelet count below 400 X 10(9)/l. Median survival was 11.1 years from diagnosis which is equal to or marginally better than with other reported regimens. Vascular causes of death were only a little higher than expected in a comparable normal population. Only deaths from acute leukaemia and myelofibrosis were significantly increased above the normal population incidence. There was no evidence to suggest that these transformations were busulphan induced. Analysis of the incidence of occlusive vascular lesions lends support to an earlier recommendation that the PCV level be maintained below 0.45. No support was found for the possible disadvantages of a predominantly venesection regimen, such as iron deficiency and reactive thrombocytosis. The case is put for this use of low dose busulphan. The data presented would warrant the future inclusion of this therapeutic regime as one limb of a controlled trial.

Adult↗
PubMed1985

Electrophoretic analysis of red blood cells in polycythaemia.

In contrast with previously published observations, this study has found no increase in the net negative surface charge of the red blood cells (RBC) from patients with various forms of polycythaemia when compared with normal subjects. Two sub-populations of RBCs with different electrophoretic mobilities (EPM), termed fast and slow, were present in samples from both patients and normal individuals. Frequently, the slow cell population in RBCs from patients with polycythaemia, particularly the apparent polycythaemia sub-group, was of a lower EPM and contained more cells than the corresponding population in normal subjects. The membrane-bound sialic acid content of RBCs from patients with primary proliferative polycythaemia, associated with iron deficient RBC changes, was increased if the results were expressed per unit volume of RBCs and decreased if the sialic acid concentration was presented per number of RBCs. These results imply that differences in surface charge of RBCs are of no value in discriminating between primary and secondary polycythaemia.

Electrophoresis↗
PubMed1984

The interpretation of measured red cell mass and plasma volume in patients with elevated PCV values.

Various formulae using both height and weight have been proposed to interpret measured red cell mass (RCM) and plasma volume (PV). This paper compares four different methods for evaluating these measurements in 50 males with PCV values above 0.51 and three different methods for evaluating results in 50 females with PCV values above 0.49. Overall there was close agreement in the RCM result expressions by all methods for both males and females except at extremes of height and/or weight. The incidence of absolute polycythaemia in both sexes was influenced by the width of the normal range. When this was taken into account overall the incidence of polycythaemia was similar, but in a small number of individuals there were discrepancies of interpretation. These individual patient differences establish that decisions regarding further investigations of a patient must not rest on a strict interpretation of a measured RCM. The various methods of measured PV interpretation gave dissimilar results--in particular by one of the male PV interpretation methods. The differences in the methods almost certainly reflect methodological discrepancies in the original techniques used to establish the normal values. The differences in result expression for PV would however lead to a different incidence of relative, low plasma volume, polycythaemia by the various techniques.

Adult↗
PubMed1984

Interpretation of measured red cell mass and plasma volume in males with elevated venous PCV values.

A method of interpretation of red cell mass (RCM) and plasma volume (PV) data is described. The results in 188 males with PCV's over 0.50 places the patients in 4 groups: true (absolute) polycythemias, relative (low plasma volume) polycythemias, high normal red cell mass (HNRCM) and 'physiological variant'. Absolute polycythemias were increasingly frequent at higher PCV levels but only reached 100% at a PCV of 0.60. They showed an 18% incidence in the lower PCV range of 0.500-0.519. Relative (low PV) polycythaemia was found in 18% of the patients with PCV values in the range 0.500 to 0.599. Although the HNRCM and 'physiological variant' types found mainly in the lower PCV ranges they occurred at the 0.54 level. While this method of interpretation of RCM and PV data is perhaps arbitrary, it does provide a basis for the proper study of the common group of patients with raised PCV levels in which classification, course and treatment are uncertain. In addition the findings suggest that both RCM and PV should be measured at all levels of PCV over 0.50; that relative (low PV) polycythaemia is a real entity but less common than sometimes believed; that diuretics do not have a notable part in its causation and that the common HNRCM, 'physiological variant' groups are incompletely understood and require further study.

Diuretics↗