Red Cell Membrane Defects Research Articles

Augmentation of skin flap survival by parenteral pentoxifylline

One prime factor implicated in flap necrosis is diminished blood flow. A known corollary of morbid ischaemia is an energy-dependent reduction in red blood cell deformability associated with an increase in whole blood viscosity. The newly available drug pentoxifylline is alleged to improve this red cell membrane defect in the low flow state, thereby improving the rheologic characteristics of blood. We studied its effect in a flap model with an ischaemic component and also measured changes in blood viscosity. A caudally-based dorsal flap in a rat model was used. Control (saline-treated) animals exhibited 74.8±9.8% flap survival. Three groups of animals were treated at different times with pentoxifylline with respect to date of surgery; all groups showed a statistically significant increase in flap survival compared to controls, ranging from 92.3 to 94.3% (p <.01). Simultaneous viscometric measurements with a cone-plate viscometer were performed. The observed increases in flap survival did not, as suggested by other investigators, correlate dependably with viscosity reduction. Reasons for this are discussed.

The Common Anemias

LIKE fever, anemia is a sign of It has many causes, most of them quite rare. In this article, advances in our understanding of only three of most common forms of anemia will be discussed. These are thalassemia, iron deficiency, and, for want of a better name, the anemia of chronic disease. I do not wish to slight either importance or interesting nature of advances in understanding of other anemias. However, such disorders as sickle cell anemia; hemolytic anemias caused by membrane defects of red blood cells, enzyme deficiencies, or antibodies; megaloblastic anemias; myelodysplastic anemias; and paroxysmal nocturnal hemoglobinuria will not be discussed here. The collective frequency with which these disorders occur does not approach that of thalassemia, iron deficiency, and anemia of chronic disease (Fig 1). THE THALASSEMIAS The inclusion of thalassemia among most common of anemias may

Aplastic anaemia: an analysis of 174 patients.

The authors summarize their experience with 174 patients with aplastic anaemia (AA) with particular reference to course, prognostic factors, conversion to other blood disorders, treatment and outcome. Aplastic anaemia was defined as pancytopenia and a hypocellular marrow at some time during the illness. Seven patients terminated with acute leukaemia, 8 developed haematological features of sideroblastic anaemia and 5 showed a red cell membrane defect commonly found in paroxysmal noctural haemoglobinuria. Complete recovery occurred in only 4 patients; 70 others showed a partial remission with some residual haematological abnormality in peripheral blood. Eighteen of these had spontaneous remission. Remission was brief in 27 patients who died; only 32 patients remained in partial remission. Twenty-five per cent. of the patients with AA run an acute course and die within 6 months of the time of diagnosis. The remainder run a subacute or chronic course, punctuated in some cases by a transient remission, but in others by a conversion to other related haematological disorders. An acute course is suggested by a rapid onset of symptoms, a falling neutrophil count, a haemoglobin level less than 5 g/dl and a very low platelet count. A chronic course is likely in those patients who have a slow onset of symptoms, a stable neutrophil count and a Hb level in excess of 5 g/dl. The authors' experience shows that the disease runs either of the 2 courses irrespective of the supportive therapy.

Partial Albinism and Immunodeficiency: Ultrastructural Study of Haemophagocytosis and Bone Marrow Erythroblasts in one Case

The ultrastructural study in one case of a new syndrome transmitted as an autosomal recessive character, associating partial albinism and immunodeficiency, with autosomal recessive transmission, is presented. The pathological findings resembled those found in cases of familial haemophagocytic reticulosis. The mononuclear phagocyte system was activated in the skin, liver and bone marrow. Phagocytosis of erythrocytes and platelets was intense in the liver and the bone marrow. Atypical intererythroblastic junctions were observed in the bone marrow in association with erythroblastophagocytosis by the macrophages. In the presence of the patient's serum, red blood cells from the patient could be phagocyrosed in vitro, using phagocytes from healthy donors. These findings are suggestive of a red cell membrane defect linked to a serological factor, acting together to induce erythrophagocyrosis. The peripheral heamophagocytosis, in addition to phagocytosis of erythroblasts in the bone marrow, appear to be the main cause of acute pancytopenia in this disease. In addition, the previously described abnormalities (i. e. capping of con A receptors on polymorphonuclear leucocytes, T cell helper and cytoroxic defects, abnormal pigment transfer by melanocytes) and the erythroblastic synartesis suggest that there is a widespread cell membrane defect in this disease.

Hemolytic disorders associated with a primary red cell membrane defect.

Hemolytic disorders associated with a primary red cell membrane defect.

Mediterranean stomatocytosis: A possible red cell membrane defect

Stomatocytes are red cells in which the usual central pale area becomes elongated, so that the cell has the appearance of a pair of lips forming a mouth. In cases referred to as showing 'stomatocytosis' more than 10% of the red cells are stomatocytes. The authors searched for such cases over 18 mth., after one of them had gained the impression that stomatocytosis was frequently seen in Mediterranean migrants to Australia. The haematological investigation of 50 such cases was described and included family studies which suggested its inheritance as an autosomal dominant. Thirty-five had haemoglobin concentrations within the normal range, the remainder having mild to moderate anaemia, the lowest haemoglobin being 8g./100 ml. The anaemia appeared to be haemolytic in type. Thrombocytopenia was observed in 20 of 30 cases where platelet counts were performed, varying from 38- to 130,000mm.³. Reticulocytes varied from 2.2 to 7.4% in 19 of 26 cases, and slight splenomegaly in 10 out of 13 cases examined. Splenectomy was undertaken in one anaemia case with good result. Most patients presented to their doctors with a variety of complaints, none of which were clearly haematological. Acyltransferase activity was measured in 3 cases and significant reduction observed. It is possible that stomatocytosis may be caused by an abnormal red cell lipid partem resulting at least in part from a lowered level of acyltransferase. However, incubation of normal compatible red cells for 24hr. with plasma from patients with stomatocytosis did not induce stomatocyte formation and conversely stomatocytosis was not reversed when incubated for 24hr. at 37° in normal plasma. The plasma and red cells of 6 cases were analysed for sodium and potassium concentration and no evidence was found of the increased potassium/sodium flux across the red cell membrane such as has been described in two previously published studies of stomatocytosis.