Red Blood Cell Size Research Articles

Evidence for linkage of red blood cell size and count: Genome‐wide scans in the Framingham Heart Study

Red blood cell (RBC) count and size are major criteria for evaluating anemia and related hematology disease diagnoses. While environmental factors influence RBC count (RBCC) and size, mean corpuscular volume (MCV), and mean corpuscular hemoglobin (MCH), studies have indicated that each of these measures has a substantial genetic component. So far, no linkage analysis or genome scan has been reported. We carried out 10 cM genome-wide scans on RBCC, MCV, and MCH in a community-based Caucasian cohort, the Framingham Heart Study, using 325 pedigrees with 1,144 individuals genotyped and phenotyped. Using variance-component linkage methods, heritabilities were estimated as 56, 52, and 52% after covariate adjusted for RBCC, MCV, and MCH, respectively. For RBCC, we found a maximum LOD score of 3.2 on chromosome 19, 24 cM (7.0 Mbp). Near this region, there lie a few important candidate genes, including erythropoietin receptor and erythroid Krüppel-like factor. For linkage analyses for MCV and MCH, there were coinciding maximized LOD scores on chromosome 11, 9 cM (5.2 Mbp) with values of 3.8 and 3.6, respectively. Under the peak resides the hemoglobin beta cluster - several beta-like genes, which are important candidates for RBC size. In subsequent analyses, we excluded individuals with low MCV to assess the possible influence of beta-thalassemia carriers, and there continued to be evidence for linkage in the same region on chromosome 11p15 (LOD scores of 2.6 and 2.7 for MCV and MCH, respectively). For MCV, we also identified a new region on chromosome 6q24 with a LOD score of 2.9. These findings suggest that further studies are warranted to identify potential causal genetic variants for RBC size and count and related erythrocyte indices.

Predicting iron and folate deficiency anaemias from standard blood testing: the mechanism and implications for clinical medicine and public health in developing countries

BackgroundDeveloping countries have high prevalence of diseases, but facilities to diagnose and treat them are limited. We must use available resources in ways not needed where there are sophisticated equipment and trained staff. Anaemia is common; iron deficiency affects health and productivity; folate deficiency in pregnant women causes foetal abnormalities. Few developing countries can measure serum folate or ferritin, but standard automated blood analyses are widely available and can help predict folate and iron deficiency. The RDW-CV% (coefficient of variation of the red cell width) measures the variability in the size of red blood cells (RBC) in routine automated analysis of blood cells, but is seldom reported. Levels of RDW-CV% and haemoglobin (Hb) can predict iron deficiency anaemia.Method and resultsI have written a computer model based on the standard mechanism for blood formation and destruction. This shows that before anaemia develops and during recovery, there are both normal and abnormal RBC (small in iron deficiency and large in folate deficiency) in the circulation. The model calculates the abnormality in the RDW-CV% in standard automated blood analyses. In early iron deficiency and during recovery the full blood count shows the Hb near the lower limit of normal, a low MCV and a high RDW-CV%. A similar pattern, but with a higher MCV, develops in folate deficiency. Folate deficiency is often brief and may not cause anaemia. The high RDW-CV% may persist for three months.ConclusionThis long footprint could be medically useful for detecting folate deficiency and so limiting foetal damage in individuals and communities. Few clinicians or public health workers know about RDW-CV%. Standard blood reports for clinical use should include the RDW-CV% and note the possible significance of abnormal values.

Valores da Amplitude de Distribuição do Tamanho dos Eritrócitos (RDW) em eqüinos Puro Sangue Inglês (PSI) submetidos a exercícios de diferentes intensidades

O presente estudo foi delineado para avaliar as alterações nos valores da amplitude de distribuição do tamanho dos eritrócitos (RDW) e do volume globular médio (VGM) em eqüinos PSI submetidos a exercícios de diferentes intensidades. Foram colhidas amostras de sangue de 60 eqüinos, PSI, sendo 30 machos e 30 fêmeas, distribuídos nos seguintes grupos: eqüinos de 24 a 36 meses de idade não submetidos a treinamento e após um período de 12 meses de treinamento; eqüinos de 36 a 48 meses de idade em fase de treinamento, antes e após o trote e antes e após o galope. As amostras foram processadas no contador automático de células Cell-Dyn 3500R (Abbott Diagnostic). Os valores médios obtidos para o RDW aumentaram significativamente após o trote e galope, demonstrando ocorrer alteração no grau de anisocitose porém os valores do VGM não apresentaram alterações nesses mesmos momentos.

Development of standard tests to examine viscoelastic properties of blood of experimental animals for pediatric mechanical support device evaluation.

We investigated the applicability of measuring the viscoelasticity of bovine, ovine, and porcine whole blood for the evaluation of sublethal damage to red blood cells (RBCs). An increase in blood viscosity and elasticity without changes in hematocrit and plasma viscosity would signify a decrease in RBC deformability. Blood viscoelasticity was assessed using a Vilastic Scientific viscoelastometer. Due to the natural absence of RBC aggregation and small RBC size in normal bovine and ovine blood, viscoelastic properties are less readily detected. However, we found that adjustment of blood hematocrit to a standard level of 40-50% allows for sensitive assessment of viscoelasticity in these blood types demonstrating a marked non-Newtonian behavior mostly related to RBC deformability. Porcine blood showed a pronounced non-Newtonian behavior at all tested hematocrit values, which makes it rheologically comparable to human blood. Both viscosity and elasticity were elevated after blood exposure to a uniform mechanical stress. RBCs rigidified by heat exposure demonstrated a loss of viscoelasticity dependence on shear rate. Measurements of blood viscoelasticity can be meaningful in bovine, ovine, and, especially, porcine blood, and can be used for evaluation of sublethal blood damage during in vitro and animal trials of heart-assist devices.

Blood Viscosity and its Relationship to Iron Deficiency, Symptoms, and Exercise Capacity in Adults With Cyanotic Congenital Heart Disease

This study sought to determine the relationship between blood viscosity and iron deficiency and their impact on symptoms and exercise function in adults with cyanotic congenital heart disease. Iron deficiency is believed to raise whole blood viscosity in cyanotic congenital heart disease, although available data are inconsistent. Thirty-nine cyanotic adults were prospectively assessed for iron deficiency (transferrin saturation < or =5%), hyperviscosity symptoms, and exercise capacity. Same-day measurement of whole blood viscosity and hematocrit (Hct) adjusted viscosity (cells resuspended in autologous plasma to Hct of 45%) was performed at shear rates ranging from 0.277 s(-1) to 128.5 s(-1). Viscosity did not differ between patients with iron deficiency (n = 14) and those without (n = 25). Whole blood viscosity correlated with Hct (r = 0.63, p < 0.001 at low shear and r = 0.84, p < 0.001 at high shear) but not with red blood cell size or iron indices. Hyperviscosity symptoms were independent of iron indices but directly correlated with increased Hct-adjusted viscosity (r = 0.41, p = 0.01). Exercise capacity did not differ in iron-deficient patients. However, peak oxygen consumption was higher in those with Hct > or = 65% (12.6 +/- 3.4 ml/kg/m2 vs. 9.8 +/- 2.6 ml/kg/m2, mean +/- SD, p = 0.036) despite higher whole blood viscosity in these same individuals (p < 0.01 for all shear rates). Iron deficiency is common in cyanotic adults but does not alter viscosity. Hyperviscosity symptoms are associated with a higher Hct-adjusted viscosity independent of cell size or iron stores. Higher Hct is associated with better exercise capacity. Further work to understand the origin of hyperviscosity symptoms is warranted.

Defocusing microscopy: An approach for red blood cell optics

Thin transparent objects (phase objects) can become visible in a bright-field light microscope, if the microscope is slightly defocused. Thick transparent objects, like red blood cells (RBC), are seen because some of their parts are always out of focus. By applying our recently developed defocusing microscopy technique to RBC, we are able to interpret RBC bright-field light microscopy images, an old standing problem. From the average image contrast we obtain RBC shape, size, and refractive index. From contrast fluctuations caused by the flicker phenomenon, we obtain RBC bending modulus and cytoplasm viscosity.

Red blood cell size and the Fåhraeus–Lindqvist effect

The reason for the large interspecies variation in vertebrate red blood cell (RBC) size is poorly understood. To test the effect of RBC size on blood viscosity, blood samples from two vertebrates, the dog (Canis familiaris L., 1758) and the greater siren (Siren lacertina L., 1766), with extremely different RBC sizes were examined. In this study, we examined whether RBC size altered the relationship of viscosity and viscometer tube diameter, the well-known Fåhraeus–Lindqvist effect (FLE). We used a glass capillary viscometer that incorporates tubes with a diameter narrow enough to evoke the FLE. At similar RBC concentrations, viscosity of suspensions with the larger siren RBCs were greater than the viscosity of suspensions with the smaller dog RBCs. However, the relationship between viscosity and tube diameter is independent of RBC size. The results of this study allow us to conclude that the FLE is not related to RBC size. While packaging hemoglobin in RBCs appears adaptive by reducing blood viscosity through the FLE, RBC size does not contribute to the reductions in tube-relative viscosity.

Simultaneous determination of size and refractive index of red blood cells by light scattering measurements

We present a fast and accurate approach for simultaneous determination of both the mean diameter and refractive index of a collection of red blood cells (RBCs). The approach uses the peak frequency of the power spectrum and the corresponding phase angle obtained by performing Fourier transform on the measured angular distribution of scattered light to determine these parameters. Results on the measurement of two important clinical parameters, the mean cell volume and mean cell hemoglobin concentration of a collection of RBCs, are presented.

Evaluation of Red Blood Cells of Healthy Subjects and Patients with Myelodysplastic Syndrome

Atomic Force Microscopy (AFM) is a recent technique that allows evaluation of features in biological systems that could not be previously observed by other instruments. Red Blood Cells (RBC) have been extensively studied because of their relatively simple membrane structure, convenience of preparation and scanning [1]. As an ancillary way of confirming diagnoses, AFM has mostly been used to determine shape and size of RBCs, which are important indicators of some blood diseases or disordered erythropoiesis [2]. In Myelodysplastic Syndrome (MDS) hematopoiesis is inefficacious with consequent anemia that may evolve to acute leukemia. Genomic alterations lead to structural defects in the biomolecular network that forms the erythrocyte membrane. The deformation capability of the cells and their lifetime in circulation are diminished [5]. AFM allows us to observe in a controlled way the response of these membrane molecular networks under physical and chemical stimuli in many different physiological conditions, such as in air and liquids [6]. Using this technique, many new characteristics have been found in erythrocyte membranes that are still of undetermined significance [3,4]. The aim of our work is to compare membrane morphology of two groups of blood donors, that is, healthy subjects and patients with MDS. The images yielded by AFM confirm the structure of the erythrocytes and reveal interesting submicron features on the cell, suggesting a way to distinguish between RBCs from healthy donors and RBCs from patients with MDS.

Sideroblastic Changes Can Be Recognized in the Erythrogram.

The scatter plots of red blood cells (RBC), called erythrogram produced by the ADVIA® 2120 cell counter gives a visual representation of RBC characteristics. Using a pair of threshold gates on each axis, nine areas are defined according to the cell volume and the hemoglobin (Hb) content. Normal RBC are distributed in the central quadrant. In diseases such as iron deficiency and thalassemia the erythrogram shows a characteristic pattern commonly used for diagnostic approach. We observed in patients, mainly with myeloid diseases with ringed sideroblasts (RS) in the bone marrow a particular erythrogram pattern with a broad distribution of the RBC and a marked variation in RBC size and hemoglobinization. From the central quadrant an abnormal RBC population shifts on an imaginary axis to the lower-left quadrant representing a tail advancing into the microcytic and hypochromic quadrants (Fig1). To confirm whether this particular erythrogram was predictive for bone marrow sideroblastic changes; we compared retrospectively the erythrogram of patients with RS to a group of myeloid diseases without RS. Between January 2004 and August 2005, 33 of 1973 cases with more than 15% of RS in the marrow were identified, 21/33 patients were evaluable (AML=2, MDS=13, MPS=1, MDS/MPS=3, non neoplasia=2). These patients were compared to 30 consecutive cases with myeloid diseases without RS (No RS) (AML=16, MDS=11, MPS=2, MDS/MPS=1). In addition to the erythrogram pattern, Hb, RBC indices, and bone marrow iron staining were analyzed in both groups. We defined two types of erythrogram pattern in respect of sideroblastic changes: a) typical (fig1) b) non typical: any other pattern (i.e. macrocytosis, fig 2). The erythrogram was typical in 17/21 patients with RS and in 0/30 patients with No RS (p<0.0001). The positive predictive value for sideroblastic changes was 100% and the negative predictive value was 88%. Despite the RBC indices comparison showed statistical significance in some variables, they were not specific enough to identify sideroblastic changes. In the group with RS, mean cell Hb was lower (median 30.8 versus 33.6pg), RBC distribution width was higher (19.3 versus 16.5%), the % of hypochromic RBC was higher (5.3 versus 0.9%) and Hb content of reticulocyte was lower (33 versus 37 pg) compared to No RS patients (p<0.05). This last index was particularly useful to rule out iron deficiency in RS group as a cause of hypochromic RBC changes, since in contrast to iron deficiency it was not decreased. In conclusion: sideroblastic changes can be recognized in the erythrogram. Indeed, despite myeloid diseases with RS are a heterogeneous group of diseases they have a common pattern of RBC distribution that can be considered as a kind of fingerprinting for sideroblastic changes with a high predictive value allowing a straightforward diagnostic approach in clinical practice. [Display omitted] [Display omitted]

Software (KEIO-IS2) for automatically tracking red blood cells (RBCs) with calculation of individual RBC velocities in single capillaries of rat brain

Confocal fluorescence microscopy offers the potential to visualize cells at high resolution in living animals. However, studies of tissue microcirculation in vivo are limited by inability to follow individual red blood cells (RBCs) moving heterogeneously in space and time. Here we present our software (KEIO-IS2), which, in combination with high-speed (125-1000 sec-1 shutter speed) confocal fluorescent microscopy, can quantitatively treat RBC flow in single capillaries. Urethane-anesthetized Wistar rats (n=26) received intravenous injection of FITC-RBCs so that bright particles were observable flowing on a dark background with the confocal microscope (Seylaz et al. JCBFM 19:863,1999). Images were recorded directly to computer in uncompressed AVI file format. The dimensions of the measurement region were 250 micron 300 micron, with a layer thickness of ca. 20 micron, and the cortex could be scanned vertically down to 100 micron in depth. The recording period was usually 10 sec at a frame rate of 1/250 sec. The recorded movies were analyzed with MATLAB® and KEIO-IS2 software, which can track individual, rapidly moving RBCs on the acquired confocal images. The program exploits the light intensity difference between the dark background and the light RBCs in the visual field of the microscope to detect the RBCs automatically. It is possible to specify several parameters, such as the scale, the minimal RBC size and flow velocity, and the intensity threshold value, to customize the software. The algorithm for RBC tracking is as follows. First a gray level thresholding is applied to each frame to differentiate RBCs from background brightness, then all particles having at least 8 connected pixels are recognized as RBCs. Displacement of the particles in subsequent frames is analyzed, and the software builds up the tracks of the moving RBCs frame-by-frame and calculates the velocities of individual RBCs (displacement over frame interval).The results can be exported for further statistical analysis. Some results of RBC tracking through single capillaries are shown in Fig. 1a (RBC velocities ranging from 0.3–7.0 mm/s) and 1b (RBC trackings, see also M. Tomita et al. (Brain'05)). Fig. 2 shows an RBC shower in an artery of 100 micron sliced at 20 micron thickness longitudinally at its center. We could calculate intravascular velocity profiles and wall shear rates. This software would also be applicable to labeled platelets and white blood cells, providing a powerful tool for hemorrheological studies in the brain microvasculature.

Dwarf and giant geckos from the cellular perspective: the bigger the animal, the bigger its erythrocytes?

Summary Although evolutionary and ecological consequences of body size changes are relatively well understood, the proximate mechanisms of body size alteration at a cellular level are often surprisingly neglected, especially in vertebrates. The question of whether larger animals are made from larger cells is rarely tested in an explicit phylogenetic framework, i.e. among closely related species with known phylogeny. Here we explore the relationship between erythrocyte and body size in a small gecko family (Eublepharidae) exhibiting large body size variation. We found positive interspecific correlation of cell and body size. Assuming that size of other cell types changed in a similar way to red blood cell size, we can conclude than c. 15–20% of body size change in this group could be attributed to cell size variation. As larger cells are generally more frugal than smaller cells, we hypothesise that a macro‐evolutionary trade‐off exists between body complexity and energetic efficiency. We believe that knowing how particular animal lineages have solved this trade‐off during body size evolution will help us explain much of the variation in ecophysiological traits among clades as well as within them.

Cytomorphology and morphometry of small round-cell tumors in the region of the kidney

Small round-cell tumors (SRCTs), with malignant cell components measuring 10 m or less in diameter with scanty cytoplasm in alcohol-fixed smears, pose a diagnostic challenge at fine-needle aspiration cytology (FNAC), especially when they are situated in and around the kidney and need facilities such as electron microscopy, immunohistochemistry, tissue culture, and cytogenetics for their subtyping. A precise cytodiagnosis of SRCTs is important because a definite diagnosis is mandatory in preoperative diagnostic workup for presurgical chemotherapy in these cases. With this view in mind, an attempt has been made to diagnose SRCTs in the region of the kidney based on cytomorphology and morphometry alone so as to facilitate its diagnosis in a simple cytology laboratory of a developing country where facilities for auxiliary techniques are not easily available. Of 2,028 abdominal aspirates in a 12-yr period, 36 SRCTs were diagnosed in the region of the kidney by correlating with histology, radiology, and clinical features. The smears were studied for cellularity, morphology, pattern of cell arrangement, and smear background and morphometrically analyzed using an ocular micrometer. An aspirate with preponderant malignant round cells that were larger or double the size of red blood cells in air-dried smears or measured less than 10 micro in diameter in alcohol-fixed smears was considered as a small blue-cell tumor. Twenty-one were diagnosed as Wilms' tumor (WT), 10 were diagnosed as neuroblastoma (NB), 3 were ganglioneuroblastoma (GNB), 1 was a cellular congenital mesoblastic nephroma (CMN), and 1 was an adrenocortical carcinoma (ACC). Cell clusters with neuropil and cytoplasmic processes were diagnostic of NB, ganglion cells of GNB, and blastema with tubular differentiation in WT. Aspirates from CMN and ACC were considered as simulators/mimickers of SRCT because they had superficial resemblance to SRCT and their differentiating cytomorphological features observed at histology were too subtle to be noted at cytology. The latter were appreciated only on retrospective analysis after histological confirmation.Thus, morphometry in correlation with cytology, clinical history, physical findings, and radiological data is helpful in guided FNA for a definite diagnosis of SRCT in the region of the kidney. One needs to keep in mind the mimickers of small round-cell lesions at this anatomic site.

Effects of diethylene glycol butyl ether and butoxyethoxyacetic acid on rat and human erythrocytes

The toxicity of diethylene glycol butyl ether (DGBE), and its principal metabolite, butoxyethoxyacetic acid (BEAA), were assessed in vitro for rat and human red blood cells. Rat erythrocytes showed evidence of mild hemolysis when exposed to BEAA at concentrations of 5 or 10 mM for 4 h. BEAA treated rat red blood cells also showed evidence of sub-hemolytic damage: increased spherocytosis, a shift in distribution of cell size to larger cells, a significant increase in mean cellular volume, and a decrease in cellular deformability. However, DGBE had no effect on rat red blood cell morphology, cell size, hemolysis or deformability. There was no hemolysis when human red blood cells were exposed to DGBE or BEAA at the same concentrations. No changes in mean cellular volume, distribution of cell size, or morphologic appearance of human red blood cells were observed. No evidence for decreased deformability of human red blood cells exposed to DGBE or BEAA was found. In conclusion, BEAA has weak hemolytic activity and sub-hemolytic effects in vitro on rat erythrocytes, which is consistent with the finding of mild hemolysis when the parent compound DGBE is administered to rats by gavage. The absence of hemolysis or sub-hemolytic damage when human red blood cells were exposed to BEAA or DGBE in vitro indicates that it is unlikely that hemolysis will occur as a result of human exposure to DGBE.

Erythrocyte indexes, iron metabolism, and hyperhomocysteinemia in adults with cyanotic congenital cardiac disease

A high percentage of cyanotic adults (37%) with cyanotic congenital cardiac disease (CCD) presented with depleted iron stores (13 of 52) or latent iron deficiency (6 of 52), even in a CCD center in which cyanotic patient phlebotomy is mostly avoided. In many of these patients, hypochromia and microcytosis was frequent, whereas hyperchromia and macrocytosis were relatively common.Furthermore, 50% of patients presented with hyperhomocysteinemia, possibly related to folate or B vitamin deficiencies, which may increase red blood cell size and color, explaining the lack of microcytosis and hypochromia in many cyanotic patients with iron deficiency.

Reply to the letter to the editor submitted by Burkhardt et al.

In response to the letter of Burkhardt et al. (1), we concur with the authors of the letter that multi-angle light scatter can be used to establish the size and hemoglobin concentration of red blood cells (RBCs) that are isovolumetrically sphered in an appropriately formulated isotonic reagent (normal discoidal RBCs are sphered in such reagent). It is also clearly evident that knowledge of the cell size and hemoglobin content of RBCs is valuable in pointing towards RBC abnormalities. The key novelties illustrated by our work is the observations that in a carefully selected three dimensional (3D) space, the scatter signals from the 3 angular intervals of RBCs which were not sphered in the reagent did not fall close to the pre-calibrated grid of the 3D surface conserved to sphered RBCs. The abbreviation which was specifically used to refer to abnormally-shaped RBCs was AbnRBC as defined in the article Abstract on page 43. The term “AbnRBC” was not intended to refer to RBC abnormalities for cell size or hemoglobin concentration, as pointed out again on page 51 under Table 5 (note a) of our article. Thus, it was with specific reference to RBCs which were not sphered in both RBC reagents that we made our observations. In their letter, Burkhardt et al. (1) also suggest that our paper implies a discrete separation of sphered and non-sphered RBCs by the 3D method. This was not our intention and on review of our manuscript, it is difficult to understand why the authors of the letter feel that this is implied. In a situation analogous to cell volume and cell hemoglobin concentration, abnormalities in cellular shape are commonly a continuum of spectrum of magnitude rather than being compartmentalized populations. We have on hand, numerous instances in which samples containing AbnRBCs show cytometric events falling more distant from the calibrated 3D surface than is the case in normal bloods. In Figure 3 of our article, we show an example of a normal sample and a sample containing AbnRBCs. As clearly shown in Fig 3d, it was never suggested that AbnRBCs form a discrete cluster. For the proposed method to be of value, boundaries of abnormality have to be established which give reference ranges for normal RBCs. Six samples in Table 5 of our article contained AbnRBCs as shown and the results analyzed by the closest point finding software of the 3D method was compared to the blood smear results. Fairly good correlation was obtained between the two methods. Concerning schistocytes, at the time of writing the article, we were unaware of any 510(k) cleared reportable parameters pertaining to schistocyte counting derived from any of the Bayer systems. If the situation has been changed since and Bayer hematology instruments now can count and report schistocytes, thank you for informing us. On the last comment in the Letter, the authors refer to the CHr parameter as a “Gold Standard” for iron-deficiency state. To assert that the CHr is the gold standard, implying it being a reference method, is not only not supported in the literature, but is not indicated as such by any publication we can find by a recognized international laboratory standards group, such as ICSH or NCCLS. Therefore, we said that we planned to investigate this area further because the diagnostic threshold for iron deficiency seems to vary with the patient population (2, 3) and may not be reliable in individuals with elevated red cell MCV values (4) (Blood). The finding of alterations in the CHr in healthy individuals following extreme exercise also raises questions as to the specificity of the measurement (5). Perhaps, the claim of red cell parameters serving as a gold standard will require the combination of several measurements, such as both the CHr and the reticulocyte IRF (RNA content) (6). The term, anemia of chronic diseases, was used in our article to describe a broad spectrum of anemias associated with chronic disease state.

Addendum to "Regulation of the water channel aquaporin-1: isolation and reconstitution of the regulatory complex" [Cell Biol. Int. 2004(1):7-17

In a routine assay using atomic force microscopy (AFM) to image red blood cells (RBCs) under various experimental conditions, rapid increase in RBC size following exposure to water (up to a 21% increase in volume), or mastoparan (up to a 73% increase in volume) was demonstrated. The increase in size of RBCs following exposure to water was much lower when assessed by the AFM; however, this modest increase in RBC volume following exposure to water was undetectable by our light-scattering analysis. Although, 150% increase in light-scattering intensity was observed when RBCs were exposed to mastoparan (Fig. 5B; AbuHamdah et al., 2004), little change in light-scattering was detected following exposure to water. Similar to the increase in light-scattering following exposure to mastoparan, we were able to detect an increase in lightscattering when RBCs were exposed to tributyltin chloride (TBT), as previously reported by Ohkuma

A primer on anemia evaluation withcase presentations

Anemia represents a common problem encountered in daily clinical practice, affecting 3.4 million Americans. Hence, a structured approach to evaluating anemia is highly relevant in primary care. Multichannel automated analyzers have revolutionized the work of performing complete blood counts (CBCs). However, when interpreting results, clinicians must be aware of limitations encountered with these technologies, which can yield spurious red blood cell (RBC) values in certain clinical circumstances. Automated analyzers identify subpopulations of RBCs that are unexpectedly small or large or have unexpectedly low or high hemoglobin concentrations, thereby signifying aberrant RBC morphologies for review on peripheral blood smear. Results of various blood chemistries help to refine or confirm diagnostic considerations suggested by the CBC, reticulocyte count, and peripheral blood smear. Although tempo of anemia development may strongly support bleeding or hemolysis as the cause of anemia, kinetic changes in RBC mass, even due to these mechanisms, are often more subtle, suggesting possible underproduction causes of anemia. Abnormalities in white blood cell (WBC) counts, platelet counts, and WBC differentials may suggest disorders of trilineage hematopoiesis, although multiple competing factors may coexist, with certain factors affecting RBCs independent of those affecting WBCs and/or platelets. To focus diagnostic considerations, clinicians should consider anemia etiologies categorized by RBC size (mean cell volume, MCV) and morphology (eg, spherocytes, bite cells, schistocytes, target cells, teardrops). These categories include the microcytic, normocytic, and macrocytic anemias. Each of these categories are briefly reviewed, and case presentations are provided to illustrate specific points.

High-frequency backscatter and attenuation measurements of porcine erythrocyte suspensions between 30–90 MHz

There are now diagnostic ultrasonic imaging devices that operate at very high frequencies (VHF) of 20 MHz and beyond for clinical applications in ophthalmology, dermatology and vascular surgery. To be able to better interpret these images and to further the development of these devices, knowledge of ultrasonic attenuation and scattering of biologic tissues, such as blood, in the high-frequency range is crucial. VHF attenuation and backscatter experiments were made on porcine red blood cell (RBC) suspensions, for which much data on attenuation and backscatter can be found in the literature in the lower frequency range. Attenuation and backscatter at hematocrits of 6%, 10%, 15%, 20%, 25% and 30% from 30 to 90 MHz were measured using a modified substitution method that allows the utilization of focused transducers. The results show that the attenuation coefficient from all suspensions increased linearly with frequency and the backscatter coefficient for low hematocrit suspensions was found to have a maximum between 10% and 15%. At higher hematocrits, a decrease in the frequency-dependence was observed, possibly indicating that Rayleigh scattering is no longer valid because the wavelength in the VHF range is comparable to the size of a porcine RBC.

Microfluidic Control Using Colloidal Devices

By manipulating colloidal microspheres within customized channels, we have created micrometer-scale fluid pumps and particulate valves. We describe two positive-displacement designs, a gear and a peristaltic pump, both of which are about the size of a human red blood cell. Two colloidal valve designs are also demonstrated, one actuated and one passive, for the direction of cells or small particles. The use of colloids as both valves and pumps will allow device integration at a density far beyond what is currently achievable by other approaches and may provide a link between fluid manipulation at the macro- and nanoscale.