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Biomedical subjects

T C Pearson

Publications and source records attributed to T C Pearson.

At least 145 records · Page 8Linked to original sources
PubMed1990

A retrospective study of apparent and relative polycythaemia: associated factors and early outcome.

Thirty four consecutive patients (31 male, 3 female) with raised PCV (males greater than 0.51, females greater than 0.47) and normal red cell mass (apparent polycythaemia) and with normal red cell mass but a low plasma volume (relative polycythaemia) were studied retrospectively. Male sex, smoking, hypertension and diuretic therapy were found to be associated factors while obesity and excessive alcohol consumption were less clearly linked. Only three patients (all males) were negative for all these factors. Approximately 15% of patients had arterial hypoxaemia. There was no difference in the incidence of these factors in the two sub-groups. Possible mechanisms relating these factors to the raised PCV are discussed. Preliminary follow-up data show that in approximately one third of the patients the PCV returns to normal and that this is most likely in those patients with a normal recumbent PCV (at the time of the blood volume study). In one third the PCV continues to be raised, and the remainder have only intermittently raised PCV. As a result of this study, prospective studies of the incidence of hypoxaemia in these patients and of the PCV outcome with and without correction of associated factors are planned.

Adult↗
PubMed1989

Correlation of prostate-specific antigen and technetium-99m HMDP bone imaging.

For an evaluation of the clinical utility of prostate-specific antigen (PSA), 32 prostatic carcinoma patients (ages 54-76) and 13 nonprostatic carcinoma patients (ages 60-70) underwent PSA measurements and bone imaging. At the time of bone imaging, each patient's PSA value was measured by a monoclonal immunoradiometric assay. All 13 nonprostatic carcinoma patients (11 bronchogenic, 1 colon, and 1 urinary bladder) gave normal PSA values, although 6 had metastatic bone disease. The 32 prostatic cancer patients were divided into 2 groups of 16 each; PSA levels in Group 1 were abnormal (greater than or equal to ng/ml): PSA levels in Group 2 were normal (less than 4 ng/ml). In Group 1, bone images of 14 patients showed bone metastases; 6 of the 14 showed progression of metastases in a 6- to 12-month period. Two patients in Group 1 were negative for skeletal metastases. Twelve patients in Group 2 were negative for skeletal metastases; bone imaging in 1 showed regression of skeletal metastases; and 3 patients had unchanged bone lesion(s). The data indicate that PSA measurements may enhance bone imaging interpretation and provide valuable clinical monitoring of prostatic carcinoma. In the case of a patient with positive bone imaging and an unknown primary, PSA measurements may definitively determine if metastases originated from prostatic carcinoma.

Aged↗
PubMed1989

Primary thrombocythaemia: diagnostic criteria and a simple scoring system for positive diagnosis.

Forty new patients with elevated platelet counts (greater than 600 x 10(9)/l) and without palpable splenomegaly were assigned to diagnostic groups defined by essentially conventional criteria after 3 months follow up: Proliferative (17), reactive (17) or unclassified (six). Mean platelet volume (MPV), platelet distribution width (PDW), platelet nucleotide ratio (ATP:ADP), unstimulated BFU-E derived colony formation from peripheral blood, spleen scan and clinical ischaemia were assessed at the outset, with a view to defining diagnostic criteria for distinguishing primary thrombocythaemia from reactive thrombocytosis. All except the first variable were significantly associated with diagnostic group (P less than 0.05). A simple scoring system was devised: enlarged spleen on scan, or presence of BFU-E, each scored 2; elevated PDW (greater than 2 SD from mean), elevated ATP:ADP (greater than 4 SD from mean) or presence of clinical ischaemia, each scored 1. Score totals greater than or equal to 3 predicted primary thrombocythaemia, and totals less than 3 suggested reactive thrombocytosis (predictive value 89%). The system correctly predicted diagnosis in four out of four (probably six out of six) patients whose diagnosis was not apparent initially, and thus whose results were not used in constructing the scoring system. Exclusion of BFU-E from the system resulted in only one incorrect prediction in this group.

Blood Platelets↗
PubMed1989

Intravenous immunoglobulin therapy in thrombocytopenic infectious mononucleosis.

Severe haemorrhagic thrombocytopenia in infectious mononucleosis with positive Epstein-Barr virus (EBV) serology remains a threatening clinical problem. Although rare, fatalities have been reported. We present clinical, haematological and serological details of two patients with diffuse bleeding associated with this disease who failed conventional steroid treatment and who both responded promptly and effectively to infusions of intravenous immunoglobulin (i.v. Ig). A platelet immunofluorescence test was used to detect platelet antibodies in acute and recovery phase patient sera against autologous recovery platelets and against normal allogeneic group O platelets. In one patient, indirect immunofluorescence using recovery platelets detected an IgG platelet autoantibody with acute phase autologous serum. No platelet antibody was detected in the second patient. The data presented demonstrate that response to i.v. Ig is independent of serological detection of platelet autoantibodies. Therapy with i.v. Ig should be considered in any case of haemorrhagic thrombocytopenia associated with EBV infection shown to be refractory to steroid treatment.

Adult↗
PubMed1989

Pulse oximetry in sickle cell disease.

The place of pulse oximetry in monitoring arterial oxygen saturation in sickle cell disease has been evaluated. In four admissions of patients with sickle cell anaemia with varying degrees of arterial haemoglobin oxygen desaturation, pulse oximetry was compared with a simultaneous assessment of oxygen saturation by arterial blood gas measurement and oxygen dissociation curve (ODC) analysis. Close agreement was found between the oxygen saturation measured by pulse oximetry and that calculated from the measured arterial partial pressure of oxygen (PaO2) with reference to the patient's own ODC. Calculation of oxygen saturation by the blood gas analyser assuming a normal ODC was erroneous. Pulse oximetry is an accurate and effective non-invasive method for monitoring the arterial oxygen saturation in sickle cell disease.

Anemia, Sickle Cell↗
PubMed1988

Use of splenic volume estimation to distinguish primary thrombocythaemia from reactive thrombocytosis.

Splenic volume was measured by visual assessment of planar images of the spleen, and also by single photon emission computerised tomography (SPECT) using 99mtechnetium tin colloid, in a group of 33 patients with primary thrombocythaemia (PT) or reactive thrombocytosis. Volumes greater than 337 cm3 correlated strongly though not absolutely with PT, all patients with volumes greater than this figure being in the PT group. Simple visual assessment of planar images by an experienced observer matched measured splenic volumes very closely.

Adult↗
PubMed1987

Polycythaemia and thrombocythaemia in the elderly.

The investigation of elderly patients presenting with raised PCV values has been described. Suitable clinical and laboratory investigation enables the separation of those with a raised red cell mass (RCM) into three groups: primary proliferative polycythaemia (PPP), secondary polycythaemia and idiopathic erythrocytosis. Those patients with a raised PCV but normal RCM either have apparent polycythaemia (normal plasma volume) or relative polycythaemia (low plasma volume). PPP is a clonal disorder with a peak incidence in the elderly. It commonly presents with vascular occlusive symptoms/signs involving larger vessels, both arterial and venous. The microvasculature may also be involved, particularly when there is associated thrombocythaemia. Effective treatment is required to minimize the future vascular occlusive incidence and diminish the complication rate of surgery if it is ever required. Both the PCV and the platelet count, if elevated, should be adequately controlled. 32P is probably the simplest treatment and is very effective, but venesection and intermittent low-dose busulphan is equally satisfactory in the co-operative patient with good peripheral veins. Secondary polycythaemia may arise from a variety of causes, particularly from arterial hypoxaemia and renal lesions. Occasionally, more than one pathology is identified in the elderly patient. Lung disease is the most common cause of hypoxaemia. Venesection may be indicated in those patients with excessively raised PCV values. The term idiopathic erythrocytosis should only be used for patients who have been adequately investigated. These patients most commonly present with ischaemic or vascular occlusive symptoms/signs. Relative polycythaemia may be caused by fluid loss, but generally the origin of the low plasma volume is not established. Apparent polycythaemia may represent a physiological variant or a stage before the development of a definitely raised RCM. The management of idiopathic erythrocytosis, and relative and apparent polycythaemia, should initially involved removal of known risk factors if present (e.g. hypertension) with the addition of venesection in selected patients. Reactive thrombocytosis in the elderly is most commonly due to malignant disease of chronic infection. The high platelet count is usually asymptomatic, and antiplatelet therapy is rarely required. Primary thrombocythaemia (PT) is a clonal myeloproliferative disorder similar to PPP. The finding of splenomegaly, abnormal platelet morphology or function helps to separate PT from reactive thrombosis. PT most commonly presents with digital or transient cerebral ischaemia or haemorrhage.(ABSTRACT TRUNCATED AT 400 WORDS)

Aged↗
PubMed1987

Rheology of the absolute polycythaemias.

The absolute polycythaemias include all patients who have a raised red cell mass. They may be divided by clinical and laboratory investigation into: primary proliferative polycythaemia (polycythaemia rubra vera), secondary polycythaemias, and idiopathic erythrocytosis. In vitro, the PCV is the single most important determinant of whole blood viscosity with the most marked effects at low shear rates. Yield stress is also dominantly influenced by PCV. Thus in the absolute polycythaemias, from whatever cause, whole blood viscosity and yield stress are high. However, flow conditions in vivo are much more complex than those usually used in in-vitro measurements. Under normal physiological conditions, whole blood viscosity probably does not determine flow in vivo. The observed in-vitro changes are only of relevance in vivo when local or general abnormalities of flow occur. In primary proliferative polycythaemia (PPP) and idiopathic erythrocytosis, presentation with ischaemia or thrombosis (either arterial or venous) is common, and the cerebral circulation is at particular risk. The incidence of vascular occlusion is positively correlated with the PCV. There is an inverse correlation between PCV and cerebral blood flow (CBF), with untreated patients having low CBF values. This is probably a 'physiological' change related to the increased oxygen carrying capacity at high PCV values. However, in many patients, cerebral oxygen carriage actually increases on reduction of the PCV to normal. This explains the improvement in cerebral ischaemic symptoms and mental performance which may be observed following treatment. Platelet contact and adhesion to the vessel wall are increased at high PCV values and, combined with the lower blood flow in both the arteries and veins, tend to favour thrombus formation. Ischaemia causes vessel dilatation but when this is maximal the high whole-blood viscosity demonstrated in vitro is a major determinant of flow. Hence in man and experimental animals, as demonstrated in the brain, the area of ischaemia or non-perfusion following arterial occlusion is greatest at high PCV values. Patients with polycythaemia due to hypoxic lung disease have a poor prognosis. The hypoxic pulmonary vasoconstriction combined with the high blood viscosity causes an increase in pulmonary vessel resistance. PCV reduction of 0.50-0.52 leads to an improvement in work performance and mental alertness, and reduction in pulmonary vascular resistance.(ABSTRACT TRUNCATED AT 400 WORDS)

Blood Flow Velocity↗
PubMed1987

Erythropoietic colonies in a serum-free system: results in primary proliferative polycythaemia and thrombocythaemia.

The formation of erythropoietic colonies from the peripheral blood of normal subjects, patients with primary proliferative polycythaemia (PPP) and primary thrombocythaemia (PT) was studied, using a chemically defined serum-free (S-) medium. Colony formation was markedly more prominent in the presence of burst-promoting activity (BPA) and erythropoietin (Ep) than with medium alone (P less than 0.001). In cultures using medium alone, significantly more PPP patients formed colonies than the control group (P less than 0.05). In the PT group this difference did not achieve statistical significance, but the mean BFU-E yield was significantly greater than in controls (P less than 0.05). In a separate series of experiments, parallel cultures in serum-containing (S+) and serum-free (S-) systems, in the presence of BPA and Ep did not show any significant difference in colony yield. The growth of 'endogenous' colonies in cultures with serum-free medium alone could be due to a peculiar sensitivity of erythropoietic progenitors to growth factors other than Ep.

Adult↗
PubMed1987

Prophylactic blood transfusion in maternal sickle cell syndromes.

An assessment of the benefits of prophylactic blood transfusion during 51 pregnancies in women with haemoglobin SS, haemoglobin SC and haemoglobin S-beta-thalassaemia in a retrospective study from 1978 to 1984 has failed to demonstrate any clear conclusions as to their efficacy. Of the transfused patients, 22% developed atypical red cell antibodies and 14% had immediate minor transfusion reactions. Our data show no significant difference in fetal or maternal outcome between those patients who were transfused prophylactically and those who were not. A prospective study to clarify the appropriate place of this important aspect of management in women with sickle cell disease in pregnancy is suggested.

Anemia, Sickle Cell↗
PubMed1987

Patterns of in vitro BFU-E proliferation in different forms of polycythaemia and in thrombocythaemia.

To investigate erythroid colony formation in polycythaemia of different types and in thrombocythaemia, a study was performed in 121 subjects, including 13 normal volunteers (N), 30 patients with Primary Proliferative Polycythaemia (PPP), 35 with Idiopathic Erythrocytosis (IE), 19 with Secondary Polycythaemia (SP), 10 with Primary Thrombocythaemia (PT) and 14 with Secondary Thrombocytosis (ST); BFU-E colony formation from peripheral blood samples was studied in the presence of medium only, medium plus a source of burst-promoting activity (BPA) and medium BPA, plus erythropoietin (Ep). In the presence of medium only, practically no colonies were seen in cultures from N and SP, while a variable number was observed in cultures from PPP, IE and PT. Significant differences between groups were as follows: N v PPP; IE v PPP; SP v PPP; N v PT; ST v PT. Such differences persisted in the presence of BPA, but disappeared when Ep was added to the cultures. Further experiments, plating non-adherent mononuclear cells in a chemically defined serum-free medium, confirmed the growth of tiny erythropoietic colonies from circulating stem cells of patients with PPP and PT, in the absence of BPA and EP. These results provide a useful criterion to differentiate PPP, as a group, from other types of polycythaemia; individual cases of IE may need further characterization.

Blood Proteins↗
PubMed1987

Zinc status in polycythaemia.

Zinc and iron status have been measured in three groups of polycythaemic patients managed by venesection: polycythaemia rubra vera, secondary polycythaemia and idiopathic erythrocytosis. Zinc status was assessed from the concentration of zinc in polymorphonuclear cells (PMN) and plasma. The mean PMN zinc value was lower than that of age-matched controls (polycythaemics 57.5 +/- 2.3 micrograms/10(10) PMN, n = 26; controls 68.9 +/- 5.2 micrograms/10(10) PMN, n = 9; means +/- SEM, p less than 0.05). The difference was most marked in polycythaemia rubra vera; the patients were iron-deficient. The reduced PMN zinc levels may indicate that polycythaemic patients managed by repeated venesection are zinc-deficient. This may contribute to some nonspecific symptoms of polycythaemia and to recurrent infections in the hypoxic patients.

Aged↗
PubMed1987

Avascular necrosis of the femoral head in sickle cell syndrome: a report of 5 cases.

The course and management of avascular necrosis of the femoral head (AVNFH) in six hips of 5 sickle cell syndrome patients (3 with Hb SS, 1 with Hb SC and 1 with Hb S/beta+-thalassaemia) are described. Two patients (aged 13 and 17 years) presented with Perthes- and osteochondritis dessicans-type lesions. These hips progressed to roller-bearing-type joints with good function and no pain following conservative management of weight restriction and rest. Three patients (aged 14, 22 and 30 years at original presentation) suffered whole-head necrosis. Initially, these 3 patients had four hip joints replaced, two cemented-stemmed types, one cemented double-cup and one uncemented hemi-arthroplasty. All four joints failed and were revised 21-61 months after the original operation. One of the revision hips has now failed and is awaiting further surgery. These results demonstrate that it is very difficult to achieve a successful hip arthroplasty in the sickle cell syndrome patient.

Adult↗
PubMed1987

Evaluation and treatment of early hemorrhage of the alimentary tract after selective shunt procedures.

The cause and treatment of early variceal bleeding in 15 patients who had undergone distal splenorenal shunt were reviewed. Eight of these patients were taken from a group of 91 who underwent selective shunts from July 1983 through June 1985 and had extensive preoperative and postoperative evaluation of shunt patency and pressure gradient. Seven patients operated upon before July 1983 were reviewed because they illustrate the cause, diagnosis, successful and unsuccessful management of bleeding after selective shunt. Urgent selective arteriography combined with shunt catheterization is the key diagnostic and therapeutic maneuver. Thrombosis of the shunt can be successfully managed by revising the anastomosis. Stenosis of the shunt can be successfully treated with balloon dilation or operative revision of the anastomosis. When renal vein hypertension (RVH) occurs, there might be inadequate decompression of the varices. A gradient of 10 millimeters of mercury or greater from left renal vein to vena cava is diagnostic. Measurements of 30 patients who had no bleeding and one patient with documented RVH show the gradient decreases over time. Treatment should be supportive until this adaptation occurs. Hemorrhage can also occur in patients with a patient shunt but without a significant pressure gradient. Inadequate decompression of the varices through the short gastric veins leading to the spleen has been proposed as one cause. Termed short gastric hypertension, this syndrome could be expected to parallel RVH because the venous collaterals will enlarge and eventually decompress the varices. Treatment should be aimed toward supporting the patient until this adaptation occurs. A small number of patients continue to bleed despite these therapeutic interventions but can sometimes be salvaged with a total shunt.

Catheterization↗