Atomic force microscopy reveals involvement of the cell envelope in biomechanical properties of sickle erythrocytes.

BACKGROUND: Intracellular hemoglobin polymerization has been supposed to be the major determinant for the elevated rigidity/stiffness of sickle erythrocytes from sickle cell anemia (SCA) patients. However, the contribution of the cell envelope remains unclear. RESULTS: In this study, using atomic force microscopy (AFM), we compared the normal and sickled erythrocyte surfaces for stiffness and topography. AFM detected that sickle cells had a rougher surface and were stiffer than normal erythrocytes and that sickle cell ghosts had a rougher surface (for both outer and inner surfaces) and were thicker than normal ghosts, the latter implying a higher membrane-associated hemoglobin content/layer in the sickle cell envelope. Compared to healthy subjects, the SCA patients had lower plasma lipoprotein levels. AFM further revealed that a mild concentration of methyl-ß-cyclodextrin (MßCD, a putative cholesterol-depleting reagent) could induce an increase in roughness of erythrocytes/ghosts and a decrease in thickness of ghosts for both normal and sickle cells, implying that MßCD can alter the cell envelope from outside (cholesterol in the plasma membrane) to inside (membrane-associated hemoglobin). More importantly, MßCD also caused a more significant decrease in stiffness of sickle cells than that of normal erythrocytes. CONCLUSIONS: The data reveal that besides the cytosolic hemoglobin fibers, the cell envelope containing the membrane-associated hemoglobin also is involved in the biomechanical properties (e.g., stiffness and shape maintenance) of sickle erythrocytes.

Hematopoietic Stem Cell Transplant for Sickle Cell Disease: PATIENT SELEction and Timing Based on Sickle Cell-Related Multiple Chronic Conditions.

Hematopoietic stem cell transplant (HSCT) is the only cure for patients with sickle cell disease (SCD). Although most SCD patients experience progressive end-organ damage and shortened lifespans, not all patients follow the same disease course, tempo, or outcome. Therefore, the dilemma facing physicians is weighing the selection of patients and timing for the procedure against donor type and transplant-related mortality and morbidity that go up with increasing age. On the other hand, the dilemma facing the patients and families is how acceptable HSCT that carries some mortality risks to them. We have analyzed the chronic conditions due to SCD in 449 patients to determine whether SCD-related multiple chronic conditions (MCC) can be risk-stratified to identify the group of patients predicted to not only have shortened lifespans but also functional limitation and poor quality of life so that these at-risk patients can be offered HSCT early and before MCC develops. We identified that the age of onset of the first SCD-related chronic conditions strongly predicted for the risks for disease-related MCC. SCD patients who suffered their first disease-related chronic condition before age 30 years developed MCC at a rate of 19.1 times faster than those at a later age. These patients are therefore high-risk patients and should be offered HSCT early in the course of their disease before multiple organ damage intervenes, even if matched-related donors are not available. This patient selection and timing approach provides a forum for an easy-to-understand and real-time discussion, including the choice of donor type, with SCD patients and families when considering HSCT.

Antibiotics to modify sickle cell disease vaso-occlusive crisis?

Despite the availability of hydroxyurea, the clinical use of the medication among patients with sickle cell disease (SCD) remains low in the United States. Given the high healthcare utilization cost, SCD requires new therapeutic approaches. Recent studies demonstrated bacterial overgrowth and dysbiosis-related intestinal pathophysiological changes in SCD. Intestinal microbes regulate neutrophil ageing. Aged and activated neutrophils contribute to the pathogenesis of vaso-occlusive crisis (VOC) in SCD. In this paper, we will review the pre-clinical and clinical data on how antibiotics might reduce the intestinal microbial density and influence the course of VOC. Based on these observations, we will discuss rationales for and potential challenges to antibiotic-based therapeutic approaches that may modify the clinical course of VOC in SCD.

Obesity and diabetes mellitus in patients with sickle cell disease.

Obesity and diabetes mellitus are prevalent among the African-American/Black population. They result in multiple chronic conditions that impact the quality and lifespan of the patients. Their occurrence in patients with sickle cell disease (SCD) will increase the risks for multimorbidity in these patients. We have carried out a chart survey of a cohort of 449 patients with SCD to determine the prevalence rates of obesity and diabetes mellitus in these patients. SCD patients were less likely to develop obesity and diabetes mellitus, compared to their peers of the same race/ethnicity. The lower prevalence rates were observed in those over the age of 6 years, irrespective of the gender of the patients. Their life-time probabilities for obesity and diabetes mellitus were also low. Within this group of SCD patients, obesity was associated with significantly higher prevalence of diabetes mellitus. The underlying reasons for our observed results of low prevalence rate of obesity in SCD remain speculative but may be related to reduced calorie intake, increased calorie use due to hypermetabolism, reduced intestinal absorption, or intestinal dysbiosis.

Case Report: Diffuse T wave inversions as initial electrocardiographic evidence in acute pulmonary embolism.

Acute pulmonary embolism (PE) is a life-threatening condition and is typically diagnosed by a combination of symptoms, clinical signs and imaging. Electrocardiogram may be helpful in diagnosis, and the most widely described pattern of occurrence is the so-called S 1Q 3T 3 pattern. Here, we describe the case of an African-American male who presented with typical chest pain, diffuse T wave inversions with serial troponin elevation. There was initial concern for Wellen's syndrome but was finally diagnosed as acute PE. This case underscores the necessity of vigilance and a lower threshold for PE work up even in patients presenting as acute coronary syndrome.