Expression of South East Asian Ovalocytic Band 3 Disrupts Erythroblast Cytokinesis and Reticulocyte Maturation

Southeast Asian Ovalocytosis results from a heterozygous deletion of 9 amino acids in the erythrocyte anion exchange protein AE1 (band 3). The report of the first successful birth of an individual homozygous for this mutation showed an association with severe dyserythropoietic anemia. Imaging of the proband’s erythrocytes revealed the presence of band 3 at their surface, a reduction in Wr(b) antigen expression, and increases in glycophorin C, CD44, and CD147 immunoreactivity. Immunoblotting of membranes from heterozygous Southeast Asian Ovalocytosis red cells showed a quantitative increase in CD44, CD147, and calreticulin suggesting a defect in reticulocyte maturation, as well as an increase in phosphorylation at residue Tyr359 of band 3, and peroxiredoxin-2 at the membrane, suggesting altered band 3 trafficking and oxidative stress, respectively. In vitro culture of homozygous and heterozygous Southeast Asian Ovalocytosis erythroid progenitor cells produced bi- and multi-nucleated cells. Enucleation was severely impaired in the homozygous cells and reduced in the heterozygous cells. Large internal vesicular accumulations of band 3 formed, which co-localized with other plasma membrane proteins and with the autophagosome marker, LC3, but not with ER, Golgi or recycling endosome markers. Immunoprecipitation of band 3 from erythroblast cell lysates at the orthochromatic stage showed increased interaction of the mutant band 3 with heat shock proteins, ubiquitin and cytoskeleton proteins, ankyrin, spectrin and actin. We also found that the mutant band 3 forms a strong interaction with non-muscle myosins IIA and IIB, while this interaction could not be detected in wild type erythroblasts. Consistent with this, the localization of non-muscle myosin IIA and actin was perturbed in some Southeast Asian Ovalocytosis erythroblasts. These findings provide new insights toward understanding in vivo dyserythropoiesis caused by the expression of mutant membrane proteins.

Maxillary osteotomies

In the past decade, biological studies on the maxilla have led to variations in established maxillary osteotomy techniques. Three of these surgical innovations are presented with illustrative case histories.

The value of a simple medical questionnaire in dentistry

A short specific medical questionnaire was given to 1125 new patients attending for their initial examination at the Perth Dental Hospital. A positive history was given by 398 patients. A wide variety of conditions was revealed and the dental significance is discussed. The extent of the information provided illustrates that the simple questionnaire is valuable in exposing conditions which may affect dental treatment.

Teeth and infective endocarditis

Despite a lack of certain knowledge regarding the role of the teeth in the aetiology of endocarditis, antibiotic prophylaxis should be given before gingival blood vessels are opened in cases of rheumatic heart disease. Much higher doses are required in patients with prosthetic heart valves. Full clearance of the teeth should be considered when a patient has already had an attack of endocarditis or where a prosthetic heart valve has been placed. Strict oral health is required in patients at risk.