Effects of hemoglobin concentration on hyperdynamic circulation associated with portal hypertension

BACKGROUND: Chronic anemia caused by different factors is a common complication in patients with portal hypertension, but attention has been rarely paid to its detrimental effect on hemodynamic status. This study was undertaken to investigate the effects of hemoglobin concentration on hyperdynamic disturbance associated with portal hypertension (PHT). METHODS: According to blood hemoglobin level of 120 g/L, 55 patients with portal hypertension were divided into two groups, anemic and nonanemic. Hemodynamic and clinical data of the patients were analyzed retrospectively. The data were analyzed separately according to the Child classification in an attempt to avoid the effects of differences on hepatic function. RESULTS: Compared with the nonanemic group, the anemic group had an increased cardiac output (7. 4 ± 1. 7 L/ min vs. 6.3+1.9 L/min, P =0. 028), free portal pressure (29. 1 ±3. 1 mmHg vs. 26.8 ±3.3 mmHg, P =0.012), a decreased mean arterial pressure (84.0 ± 10.7 mmHg vs. 97.1 ±12.0 mmHg, P<0.01), and systemic vascular resistance (866 ±215 dyn/s ·cm5 vs. 1207 ±317 dyn/s ·cm5, P <0.01). Similar results were obtained when Child A and Child B-C patients were analyzed separately. Multivariate logistic regression revealed that the concentrations of hemoglobin (standard coefficient =0.31, P=0.01) and albumin (standard coefficient =0.21, P=0.04) were independent factors influencing the systemic vascular resistance in PHT patients. CONCLUSIONS: Anemia aggravates the hyperdynamic circulation of portal hypertension. Hemoglobin concentration is an important variable for evaluating the degree of hemodynamic disturbance in PHT patients.     

Inhibitors of cell division reversibly modify hemoglobin concentration in human erythroleukemia K562 cells

The human leukemia K562 cell line can be induced by 20 micro M hemin to reversibly accumulate embryonic and fetal hemoglobins without any change in the rate of cell division. When we reduced the rate of cell division by glutamine starvation or addition of hydroxyurea, the cells increased by tenfold the basal hemoglobin level of 0.3-0.5 pg Hb/cell. The combined effects of hemin and inhibitors of cell division permitted K562 cells to attain levels of hemoglobin (26-34 pg Hb/cell) close to that found in normal red cells. This superinduction was reversible and cells could be recycled indefinitely. Furthermore, electrofocusing experiments show that the three primary hemoglobin species produced by these cells (Hb Gower 1, Hb Portland, and fetal Hb), were induced, or reinduced, synchronously by inhibitors of cell division but asynchronously by hemin. Differing effects of hemin and inhibitors of cell division were observed in the absence of irreversible differentiation and suggest different molecular mechanisms controlling globin gene expression.     

Rate of deoxygenation modulates rheologic behavior of sickle red blood cells at a given mean corpuscular hemoglobin concentration

Although the mean corpuscular hemoglobin concentration (MCHC) plays a dominant role in the rheologic behavior of deoxygenated density-defined sickle red blood cells (SS RBCs), previous studies have not explored the relationship between the rate of deoxygenation and the bulk viscosity of SS RBCs at a given MCHC. In the present study, we have subjected density-defined SS classes (i.e., medium-density SS4 and dense SS5 discocytes) to varying deoxygenation rates. This approach has allowed us to minimize the effects of SS RBC heterogeneity and investigate the effect of deoxygenation rates at a given MCHC. The results show that the percentages of granular cells, classic sickle cells and holly leaf forms in deoxygenated samples are significantly influenced by the rate of deoxygenation and the MCHC of a given discocyte subpopulation. Increasing the deoxygenation rate using high K+ medium (pH 6.8), results in a greater percentage of granular cells in SS4 suspensions, accompanied by a pronounced increase in the bulk viscosity of these cells compared with gradually deoxygenated samples (mainly classic sickle cells and holly leaf forms). The effect of MCHC becomes apparent when SS5 dense cells are subjected to varying deoxygenation rates. At a given deoxygenation rate, SS5 dense discocytes show a greater increase in the percentage of granular cells than that observed for SS4 RBCs. Also, at a given deoxygenation rate, SS5 suspensions exhibit a higher viscosity than SS4 suspensions with fast deoxygenation resulting in maximal increase in viscosity. Although MCHC is the main determinant of SS RBC rheologic behavior, these studies demonstrate for the first time that at a given MCHC, the rate of deoxygenation (hence HbS polymerization rates) further modulates the rheologic behavior of SS RBCs. Thus, both MCHC and the deoxygenation rate may contribute to microcirculatory flow behavior of SS RBCs.     

Evaluation of a new automated affinity-chromatographic method for the measurement of glycated hemoglobin.

A new automated affinity-chromatographic method for the rapid determination of glycated hemoglobin is described. It has a four min cycle time, does not measure the labile fraction of glycosylated hemoglobin and is not interfered with by abnormal hemoglobins.     

Spectrin-haemoglobin crosslinkages associated with in vitro oxidant hypersensitivity in pathologic and artificially dehydrated red cells

S ummary . Protein crosslinkages are apparent at 215000–250000 daltons in electrophoregrams of membranes from hydrogen peroxide treated erythrocytes (British Journal of Haematology , 48 ,435, 1981). Hydrogen peroxide is also capable of inducing crosslinkages of identical molecular weights in stage I and II (red) ghosts and in a mixture of purified spectrin and haemoglobin, but not in white ghosts or in either spectrin or haemoglobin alone. Autoradiographic studies using ¹⁴C-methae-moglobin and ³²P-spectrin confirm the involvement of spectrin and haemoglobin in this reaction. The alpha chains of both proteins are more reactive than the corresponding beta chains: 3 times more reactive in the case of spectrin and 10 times more reactive in haemoglobin. The reaction is almost totally inhibited by NaCN and partially inhibited by N-ethylmaleimide. Direct addition of malondialdehyde to a spectrin-haemoglobin mixture does not result in protein crosslinkage. Metabolic depletion (40 h), in vivo ageing and sucrose dehydration of fresh, normal cells enhance the reaction considerably, whereas in vitro rehydration of xerocytes normalizes their H₂O₂ sensitivity.     

Accurate and independent measurement of volume and hemoglobin concentration of individual red cells by laser light scattering

Cell volume (MCV) and hemoglobin concentration (MCHC) are the red cell indices used to characterize the blood of patients with anemia. Since the introduction of flow cytometric methods for the measurement of these indices, it has generally been assumed that the values derived by these instruments are accurate. However, it has recently been shown that a number of cellular factors, including alterations in cellular deformability, can lead to inaccurate measurement of cell volume by these automated instruments. Because cell hemoglobin concentration and hematocrit are computed from the measured values of cell volume, accuracy of these indices is also compromised by inaccurate determination of cell volume. A recently developed experimental flow cytometric method based on laser light scattering, which can independently measure volume and hemoglobin concentration, has been used in the present study to measure MCV and MCHC of density- fractionated normal and sickle red cells, hydrated and dehydrated normal red cells, and various pathologic cells. We found that the new method accurately measures both volume and hemoglobin concentrations over a wide range of MCV (30 to 120 fL) and MCHC (27 to 45 g/dL) values. This is in contrast to currently available methods in which hemoglobin concentration values are accurately measured over a more limited range (27 to 35 g/dL). In addition, as the experimental method independently measures volume and hemoglobin concentration of individual red cells, it allowed us to generate histograms of volume and hemoglobin concentration distribution and derive coefficient of variation for volume distribution and standard deviation of hemoglobin concentration distribution. We have been able to document that volume and hemoglobin concentration distributions can vary independently of each other in pathologic red cell samples.     

育龄妇女血清铁蛋白、平均红细胞体积和平均红细胞血红蛋白量测定分析

为了探讨血清铁蛋白(SF)、平均红细胞体积(MCV)和平均红细胞血红蛋白量(MCH)检测在育龄妇女缺铁性贫血(IDA)诊断中的价值，对1314例育龄妇女(其中孕妇869例，非孕妇445例)外周血SF、MCV、MCH进行检测，其中对Hb＜110g/L的157例孕妇、Hb＜120g/L的111例非妊娠妇女及1046例非IDA对照组进行比较，并对869例孕妇按孕周分为妊娠早期组248例，中期组345例和晚期组276例进行比较。结果显示：①与对照组比较，IDA孕妇组和IDA非孕妇组的SF、MCH、MCV均显著下降(P＜0．01)。②妊娠早期组、中期组及晚期组比较，SF随孕周增加而减少，均有显著性差异(P＜0.01)；MCV、MCH未有显著性差异。认为SF、MCV、MCH降低是IDA的特征性改变，其检测有助于IDA的鉴别诊断，定期监测妇女血清SF对早期发现铁缺乏有重要意义。     

Fetal hemoglobin-containing cells have the same mean corpuscular hemoglobin as cells without fetal hemoglobin: a reciprocal relationship between gamma- and beta-globin gene expression in normal subjects and in those with high fetal hemoglobin production

We have developed methodology that allows comparison of the mean corpuscular hemoglobin (MCH) of fetal hemoglobin (HbF)-containing red cells (F cells) with the MCH of non-F cells from the same individual. To do this, suspensions of peripheral blood erythrocytes and their internal contents are fixed with an imidodiester, dimethyl-3,3'-dithiobispropionimidate dihydrochloride (DTBP). Thereafter fixed cells are made permeable to antisera by treatment with Triton X-100 and isopropanol, reacted with a mouse monoclonal antibody (MoAb) against HbF, and then with fluorescein-conjugated antimouse IgG. No appreciable hemoglobin is lost during such manipulation. Red cells from a diversity of subjects were thus treated and examined microscopically, first by transmitted light and then by epifluorescence. A direct correlation between Coulter-derived MCH and mean absorbance of 415 nm transmitted light was found for 100 unfixed (r = 0.96) and for 100 antibody-treated fixed-permeabilized red cells (r = 0.99) among individuals selected so as to provide a range of Coulter MCH values between 20 and 35. Comparisons of microscopically derived MCH of F cells and non-F cells were statistically nondistinguishable (P greater than 0.05) in all subjects. Such comparisons included normal individuals (less than 1% F cells), SS patients (7% to 48% F cells), subjects with congenital anemia (22% to 65% F cells), individuals with heterocellular hereditary persistence of HbF (HPFH) (12% to 21% F cells), and heterozygotes for beta + thalassemia (11% to 31% F cells). We conclude that gamma- and beta-globin production within F cells is regulated in a reciprocal fashion both among normal individuals and among individuals with elevated HbF production.     

Pulse oximetry and factors associated with hemoglobin oxygen desaturation in children with sickle cell disease

The observation of low transcutaneous arterial oxygen saturation (SaO2) in otherwise well sickle cell patients has lead to questions about the interpretation of pulse oximetry values in these patients. We undertook a prospective study of children with sickle cell disease to (1) determine the prevalence of, and factors associated with, low transcutaneous SaO2 in clinically well patients, (2) develop an algorithm for the use of pulse oximetry in acutely ill patients, and (3) assess the accuracy of pulse oximetry in these patients. Eighty-six clinically well children with hemoglobin (Hb) SS had a lower mean transcutaneous SaO2 than 22 Hb SC patients and 10 control subjects (95.6% v 99.1% v 99.0%, respectively; p < .001). In Hb SS patients, a history of acute chest syndrome and age greater than 5 years were associated with lower transcutaneous SaO2 (mean 93.8% for those with a history of acute chest syndrome v 97.8% for those without a history of acute chest syndrome, and 94.0% for patients > 5 years old v 97.2% for those < or = 5 years old; P < .001). These associations were not seen in Hb SC patients. During acute illness, Hb SS patients with acute chest syndrome had transcutaneous SaO2 values that were less than 96% and at least 3 points lower than measurements made when they were well. A nomogram was designed to aid in the interpretation of transcutaneous SaO2 in acutely ill Hb SS patients when a comparison value is not available. The accuracy of pulse oximetry was shown by the correlation between SaO2 measured by pulse oximetry and calculated by using the patient's oxygen dissociation curve and PaO2 (r = .97). This study provides evidence that Hb oxygen desaturation is not a universal finding among children with sickle cell disease and identifies factors associated with Hb oxygen desaturation. We conclude that pulse oximetry may be useful to assess whether progressive pulmonary dysfunction begins at an early age in Hb SS patients, and to assess acutely ill patients for the presence of hypoxemia associated with acute chest syndrome.     

Influence of hemoglobin phenotype on the mean erythrocyte volume

The influence of the hemoglobin (Hgb) phenotype on mean erythrocyte volume was re-examined in the light of recent evidence indicating a poor correlation between manual and more precise automated methods of measurement. The present studies identified a 17.6% frequency of microcytosis in a population of nonanemic Black males, a value higher than previously appreciated. In addition, it was shown that the frequency of microcytosis was also a function of the Hgb phenotype. Thus, 9.4% of Hgb AA, 18.6% of AS and 26.5% of AC subjects had microcytic erythrocytes. The data presented are consistent with the hypothesis that both the alpha-gene complement and the beta-chain phenotype contribute to the erythrocytic mean corpuscular volume and that the frequency of microcytosis in a patient population is a function of both of these variables.     

Effects of hemoglobin concentration on deformability of individual sickle cells after deoxygenation

To assess the role of intracellular hemoglobin concentration in the deformability of sickle (HbSS) cells after deoxygenation, rheologic coefficients (static rigidity E and dynamic rigidity eta) of density- fractionated individual sickle erythrocytes (SS cells) were determined as a function of oxygen tension (pO2) using the micropipette technique in a newly developed experimental chamber. With stepwise deoxygenation, E and eta values showed no significant increase before morphologic sickling but rose sharply after sickling. In denser cells, continued deoxygenation led to steep rises of E and eta toward infinity, as the cell behaved as a solid. The pO2 levels at which rheologic and morphologic changes occurred for individual SS cells during deoxygenation varied directly with the cell density. The extent of recovery in E and eta during reoxygenation varied inversely with the cell density. These results provide direct evidence that the intracellular sickle hemoglobin (HbS) concentration of SS cells plays an important role in their rheologic heterogeneity in deoxygenation and reoxygenation. The elevations of eta during pO2 alteration were greater than those of E, especially for the denser cells, suggesting the importance of the elevated dynamic rigidity in initiating microcirculatory disturbances in sickle cell disease.     

Initial blood fetal hemoglobin concentration is elevated and is associated with prognosis in children with acute lymphoid or myeloid leukemia

Summary We examined the relationship between initial blood fetal hemoglobin (HbF) concentration and prognosis in 100 children with leukemia. HbF concentration was usually elevated and ranged between 0 and 19.5 g/l. Multivariate analysis showed that, in patients with acute lymphoblastic leukemia (ALL), each increment of 1 g/l in initial HbF concentration resulted in a 1.13-fold rise in the risk of death or relapse (95% confidence limits 1.01–1.25,P<0.05). In patients with myeloid leukemias, each increment of 1 g/l in HbF was associated with a 1.20-fold (1.05–1.37,P<0.02) rise in the risk of death or relapse. In the patients with myeloid leukemias the mean initial HbF concentration was also higher (3.4 g/l; 0.5–19.5 g/l) than in the patients with ALL (1.1 g/l; 0–18.7 g/l;P = 0.08). Our results indicate that the degree of increase in HbF synthesis is associated with the degree of malignancy: the more aggressive the disease, the more augmented is the synthesis of HbF.     

Dehydroepiandrosterone sulfate levels associated with decreased malaria parasite density and increased hemoglobin concentration in pubertal girls from western Kenya

In areas where Plasmodium falciparum malaria is endemic, parasite density, morbidity, and mortality decrease with increasing age, which supports the view that years of cumulative exposure are necessary for the expression of maximal protective immunity. Developmental changes in the host also have been implicated in the expression of maximal resistance. To further evaluate the contribution of host developmental factors in malaria resistance, we examined the relationship between P. falciparum parasitemia and pubertal development in a cross-sectional sample of 12-18-year-old schoolgirls from an area of intense transmission in western Kenya. Among pubertal girls, dehydroepiandrosterone sulfate (DHEAS) levels were significantly associated with decreased parasite density, even after adjustment for age. DHEAS levels also were related to increased hemoglobin levels, even after accounting for age and other determinants of hemoglobin level. These findings support the hypothesis that host pubertal development, independent of age and, by proxy, cumulative exposure, is necessary for maximal expression of resistance to malarial infection and morbidity, as assessed by hemoglobin level.