Testican in human blood

Testican is a highly conserved, differentially expressed gene product of unknown function. Since testican is expressed by human endothelial cells and includes a signal sequence, it was our hypothesis that testican protein would be present in blood. We have developed chicken antibodies specific for testican sequence near the N-terminal and identified a 130-kDa form of testican in human plasma. This is much larger than the calculated molecular weight of the encoded polypeptide, suggesting glycosylation of this plasma protein, and large forms of recombinant testican produced in culture were found to include chondroitin sulfate. The 130-kDa form of testican is unstable in plasma. It is converted to smaller stable forms by separable plasma factors that can be blocked by certain serine protease inhibitors. Testican size conversion may be important in its functional activation or decay. One testican domain has strong homology to thyropin-type cysteine protease-inhibitors. Thus, testican may have a function related to protease inhibition in the blood.     

Red blood cells augment leukocyte rolling in a virtual blood vessel

Leukocyte rolling and arrest on the vascular endothelium is a central event in normal and pathological immune responses. However, rigorous estimation of the fluid and surface forces involved in leukocyte-endothelial interactions has been difficult due to the particulate, non-Newtonian nature of blood. Here we present a Lattice-Boltzmann approach to quantify forces exerted on rolling leukocytes by red blood cells in a "virtual blood vessel." We report that the normal force imparted by erythrocytes is sufficient to increase leukocyte binding and that increases in tangential force and torque can promote rolling of previously adherent leukocytes. By simulating changes in hematocrit we show that a close "envelopment" of the leukocyte by the red blood cells is necessary to produce significant changes in the forces. This novel approach can be applied to a large number of biological and industrial problems involving the complex flow of particulate suspensions.     

Best practices in regulation of blood and blood products

The need for blood regulation arises from the inherent risks of blood transfusion, which are minimized through implementation of standards. Regulatory oversight is advocated by the World Health Organization (WHO) as an essential element of any blood system to ensure such standards are met. The WHO Blood Regulators Network has developed "Assessment Criteria for National Blood Regulatory Systems" that describe the legal authority and functions of a fully competent blood regulator. The core functions include licensing and/or registration of blood establishments, marketing approval of blood products, oversight of all associated substances and devices, control of clinical trials, access to an independent laboratory for product assessments, lot release, and hemovigilance systems. Regulatory policy-making for blood safety is needed to address emerging threats, to consider the risks and benefits of new products and technologies, and to respond to adverse events. Structured policy-making processes are essential to ensure that decisions are science-based, with appropriate consideration of relevant economic and social factors. Decision making is especially challenging in situations of scientific uncertainty, where prudent precautionary measures may be appropriate based on assessments of risk and feasibility of meaningful interventions. There is international interest in finding a common framework for addressing blood safety decisions.     

Mechanotransduction in blood cells

Blood cells are subjected to various mechanical forces; including pressure, flow, shear force, gravity, and forces acting against them with varying stiffness (eg. blood vessel wall). Scientists have discovered that these forces have profound effects on cellular growth, differentiation, secretion of cytokines, cell death, and migration. These processes are called mechanotransduction, a conversion of mechanical forces to biochemical signals. In this article the author reviews biophysical forces that affect biological functions of blood cells and their responses in normal physiology and pathophysiology. Although input (forces) and output (cellular responses) have been well studied by utilizing recently developed various force-generating devices, the molecular mechanism of mechanotransudction is still a mystery. This is because reconstructing molecular interaction in the presence of mechanical forces in vitro is highly challenging and until now the molecular dynamics involved in structural changes caused by these forces are largely unknown. Nevertheless, the author has reviewed a few examples of potential structural effects on the molecular mechanism of mechanotransduction.     

Common origins of blood and blood vessels in adults?

After embryonic development, the vast majority of cells are differentiated and all organs are in place. Growth of the organism then ensues and continues until adulthood, whereupon cell division largely ceases. In some tissues, notably the bone marrow, skin, and gut, cell proliferation continues throughout life to replace cells lost by attrition. This regeneration is fueled by rare, long-lived, and largely quiescent stem cells that give rise to committed progenitors, which in turn generate large numbers of fully differentiated cells. Mounting evidence suggests that such cells can significantly contribute to tissue repair and regeneration in adults and may therefore prove beneficial for autologous cell and gene therapies. This review focuses on the potential of adult stem cells to give rise to hematopoietic and vascular cells. We discuss evidence that a highly purified population of adult stem cells, termed SP cells, serves as a hematopoietic progenitor and can contribute to vascular regeneration after injury. We also discuss the potential relationship of these cells to the embryonic hemangioblast.     

Calelectrin in human blood cells

Calelectrin is a new calcium-binding protein isolated from the cholinergic nerve terminals of the electric organ of Torpedo marmorata, which is widely distributed in nervous tissues and selectively binds to membranes, self-aggregates, and promotes calcium-induced membrane aggregation as a function of calcium concentration. We now show by immunofluorescence and immune blotting procedures that this protein is also present in human blood cells. Immunofluorescence demonstrates calelectrin in all human leucocytes, including mononuclear cells, but not in platelets or in erythrocytes. The immunofluorescence indicates an exclusively cytoplasmic location of calelectrin with a diffuse distribution and no primary association with the cytoskeleton or the cell membranes. SDS-polyacrylamide gel electrophoresis with immune blotting of fractionated blood cells (thrombocytes, mononuclear cells, granulocytes and erythrocytes) reveals the presence of a single protein crossreactive with calelectrin from Torpedo marmorata in the granulocyte and mononuclear cell fractions only. Human calelectrin has a molecular weight similar to Torpedo calelectrin (approximately 34-35 kD) and also binds to membranes in a Ca(2+)-dependent manner. Our results have several implications: (1) Calelectrin is conserved during evolution between the fish Torpedo marmorata and humans; (2) its expression in neural and mesenchymal cells points to an important functional role of the protein; (3) its absence from platelets excludes the hypothesis that it is a necessary participant in exocytosis per se and suggests some other function in Ca(2+)-triggered processes.     

The role of blood flow and microRNAs in blood vessel development

The circulatory system is the first organ system that develops during embryogenesis, and is essential for embryo viability and survival. Crucial for developing a functional vasculature are the specification of arterial-venous identity in vessels and the formation of a hierarchical branched vascular network. Sprouting angiogenesis, intussusception, and flow driven remodeling events collectively contribute to establishing the vascular architecture. At the molecular level, arterial-venous identity and branching are regulated by genetically hardwired mechanisms involving Notch, vascular endothelial growth factor and neural guidance molecule signaling pathways, modulated by hemodynamic factors. MicroRNAs are small, non-coding RNAs that act as silencers to fine-tune the gene expression profile. MicroRNAs are known to influence cell fate decisions, and microRNA expression can be controlled by blood flow, thus placing microRNAs potentially at the center of the genetic cascades regulating vascular differentiation. In the present review, we summarize current progress regarding microRNA functions in blood vessel development with an emphasis on studies performed in zebrafish and mouse models.     

The inheritance of blood groups in the blood group system B in cattle

The mode of inheritance of blood groups in man and animals has been a matter of discussion as long as investigations in this field have been performed.A series of aberrations from the usual transmission of genes controlling the blood groups of the system B of cattle is presented. These data offer a contribution to the assumption that the blood groups are controlled by linked genes.On leave from the Faculty of Agriculture, University of Cairo, Egypt, U.A.R.     

Detection of prions in blood

Prion diseases are caused by an unconventional infectious agent termed prion, composed mainly of the misfolded prion protein (PrP(Sc)). The development of highly sensitive assays for biochemical detection of PrP(Sc) in blood is a top priority for minimizing the spread of the disease. Here we show that the protein misfolding cyclic amplification (PMCA) technology can be automated and optimized for high-efficiency amplification of PrP(Sc). We show that 140 PMCA cycles leads to a 6,600-fold increase in sensitivity over standard detection methods. Two successive rounds of PMCA cycles resulted in a 10 million-fold increase in sensitivity and a capability to detect as little as 8,000 equivalent molecules of PrP(Sc). Notably, serial PMCA enables detection of PrP(Sc) in blood samples of scrapie-afflicted hamsters with 89% sensitivity and 100% specificity. These findings represent the first time that PrP(Sc) has been detected biochemically in blood, offering promise for developing a noninvasive method for early diagnosis of prion diseases.     

Red blood cell motions in high-hematocrit blood flowing through a stenosed microchannel

We investigated the behavior of red blood cells (RBCs) in a microchannel with stenosis using a confocal micro-PTV system. Individual trajectories of RBCs in a concentrated suspension of up to 20% hematocrit (Hct) were measured successfully. Results indicated that the trajectories of healthy RBCs became asymmetric before and after the stenosis, while the trajectories of tracer particles in pure water were almost symmetric. The asymmetry was greater in 10% Hct than in 20% Hct. We also investigated the effect of deformability of RBCs on the cell-free layer thickness by hardening RBCs using a glutaraldehyde treatment. The results indicated that deformability is the key factor in the asymmetry of cell-free layer thickness. Therefore, the motions of RBCs are influenced strongly by the Hct, the deformability, and the channel geometry. These results give fundamental knowledge for a better understanding of blood flow in microcirculation and biomedical microdevices.     

Epidermal growth factor in blood

The presence of receptors for epidermal growth factor (EGF) in a wide variety of human tissues and also some tumours indicates an as yet undefined role for EGF and it is therefore necessary to know precise concentrations in blood and other fluids. We have investigated the occurrence of EGF in the circulation and found that in platelet rich plasma, EGF levels were 51 +/- 5 pmol/l (mean +/- S.E.M., n = 6) while in platelet poor plasma levels were 2.9 +/- 0.9 pmol/1. In contrast, serum EGF was 37 +/- 7 pmol/l if separated at 30 min and rose to 117 +/- 5 pmol/l if separated at 270 min. Gel chromatography showed that all residual EGF immunoreactivity in platelet poor plasma resided in the high molecular weight form thought to be non biologically active. In serum, delay in separation resulted in an increase in the proportion of EGF immunoreactivity co-eluting with EGF standard. These results suggest that EGF in the circulation is associated with platelets and that the process of blood coagulation leads to release of free EGF.     

Gain-induced oscillations in blood pressure

 “Mayer waves” are long-period (6 to 12 seconds) oscillations in arterial blood pressure, which have been observed and studied for more than 100 years in the cardiovascular system of humans and other mammals. A mathematical model of the human cardiovascular system is presented, incorporating parameters relevant to the onset of Mayer waves. The model is analyzed using methods of Liapunov stability and Hopf bifurcation theory. The analysis shows that increase in the gain of the baroreflex feedback loop controlling venous volume may lead to the onset of oscillations, while changes in the other parameters considered do not affect stability of the equilibrium state. The results agree with clinical observations of Mayer waves in human subjects, both in the period of the oscillations and in the observed age-dependence of Mayer waves. This leads to a proposed explanation of their occurrence, namely that Mayer waves are a gain-induced oscillation. Received: 15 September 1997/Revised version: 15 March 1998     

Glucocorticoids in blood pressure regulation

Glucocorticoid excess is associated with hypertension in man and in animals. This type of hypertension is of rapid onset and independent of salt intake; it can be inhibited by glucocorticoid antagonists, such as RU486. In normal rats, RU486 blunts vascular reactivity to norepinephrine and angiotensin II. In normal rats on low-salt diet, it induces a fall in blood pressure of approximately 20 mm Hg, due to decreased vascular resistance. This suggests that in some conditions, endogenous glucocorticoids contribute to the maintenance of blood pressure by enhancing vascular reactivity.     

Study on blood constitutive parameters in different blood constitutive equations

A method is proposed to study the steady blood constitutive equation (BCE). With the method several BCEs are tested and Quemada, Bi-exponent and K-L equations are found to be well in agreement with the hemorheological characteristics of human and canine blood and these equations may be well used in hemorheology and hemodynamics. In addition, the potential clinical applications of some blood constitutive parameters (BCPs) are discussed. It is found that the hematocrit can significantly affect the BCPs: K(A) = alpha2/alpha1, Q(A) = eta0/eta(infinity), R(A) = etaA/eta(e) - 1, which means relative viscosities and they may be related to RBC aggregative level. Moreover, we also show that the parameters are related to the RBC aggregative strength and level.     

Microrheologic dysfunctions in blood during malaria

Among the Plasmodium variants that cause human malaria, vivax malaria is considered to be non-malignant. Recent research has indicated that severe vivax infection can turnout to be as pathological as falciparum. This review evidences microrheologic pathology in vivax malaria, similar to that as seen in malignant falciparum. The parasite invasion, internalization and growth in the RBC lead to membrane rigidification and progressive loss of deformability, rosetting and cytoadherence, enhanced aggregation, clumpy, non-deforming, sticky aggregates and chronic sedimentation profiles. A model that reflects the net effect of these changes is of clinical value to establish disease severity in specific malaria. In this respect an artificial neural network (ANN) model, implemented in malaria severity analysis, is discussed. Results of this model suggest that a good degree of severity classification (60 to 100%) can be achieved even with small sample size (malaria samples n = 12, normal = 10). With larger sample size, ANN may be very apt as microrheological model for severity analysis.     

Distribution of Abeta peptide in whole blood

The measurement of amyloid beta peptides (Abeta) in blood and plasma is expected to be a useful biomarker as potential therapeutics designed to lower Abeta peptide enter clinical trials. Many reports have suggested that Abeta could bind to substances in blood that may influence the recovery of Abeta peptide in plasma, its detection by conventional ELISAs or the actual turnover and half-life of the peptide in blood. In this study we describe a process for analyzing total Abeta in whole blood and plasma using denaturing solid-phase extraction followed by reverse-phase HPLC linked to ELISA. Comparison of total Abeta peptide levels in whole blood and plasma from the same bleed showed that most of the Abeta peptide is captured in the plasma if the samples are first denatured. In contrast, plasma that was assayed without denaturation could show greater than 70% reduction in apparent total Abeta peptide. This suggested that there was a pool of Abeta peptide in non-denatured plasma that is occluded from detection by ELISA, perhaps by binding to plasma proteins.     

Small disturbance in arterial blood flow

The behaviour of a small disturbance in an arterial blood flow has been studied analytically. The growth equation governing growth or decay of a disturbance has been obtained and solved. The behaviour of wave amplitude has been investigated as the wave propagates in time. The application of results to the human arterial system shows that the shock waves are not expected under normal physiological conditions. In the case of a pathologically increased pressure rise at the root of aorta, shock-like transitions may develop in the periphery. It is observed that the friction effects are to resist the tendency of shock formation in arteries.     

Fate of blood meal iron in mosquitoes

Iron is an essential element of living cells and organisms as a component of numerous metabolic pathways. Hemoglobin and ferric-transferrin in vertebrate host blood are the two major iron sources for female mosquitoes. We used inductively coupled plasma mass spectrometry (ICP-MS) and radioisotope labeling to quantify the fate of iron supplied from hemoglobin or as transferrin in Aedes aegypti. At the end of the first gonotrophic cycle, approximately 87% of the ingested total meal heme iron was excreted, while 7% was distributed into the eggs and 6% was stored in different tissues. In contrast, approximately 8% of the iron provided as transferrin was excreted and of that absorbed, 77% was allocated to the eggs and 15% distributed in the tissues. Further analyses indicate that of the iron supplied in a blood meal, approximately 7% appears in the eggs and of this iron 98% is from hemoglobin and 2% from ferric-transferrin. Whereas, of iron from a blood meal retained in body of the female, approximately 97% is from heme and <1% is from transferrin. Evaluation of iron-binding proteins in hemolymph and egg following intake of (59)Fe-transferrin revealed that ferritin is iron loaded in these animals, and indicate that this protein plays a critical role in meal iron transport and iron storage in eggs in A. aegypti.     

Detecting hepatocellular carcinoma in blood

Liquid biopsy is ideal for early diagnosis of cancer and for prognosis upon treatment. Wen et al. describe a methylated CpG tandems amplification and sequencing method to profile hypermethylated CpG islands genome-widely in cell-free DNA, and further identify high performance markers in blood for potential detection of early stage hepatocellular carcinoma.Early diagnosis is key to cancer prevention and treatment. When physiological consequences of cancer are observed it could be too late for the optimal treatment and therapy¹. Traditional biopsy has been widely used for diagnosis; however, it is difficult to frequently perform biopsy. In many cases it is impossible to perform biopsy of solid tumors grown in deep tissues. Cell-free nucleic acids (cfNAs) offer an alternative option. The presence of cfNAs in blood was described in 1948. However, cfNAs such as DNA, mRNA and microRNAs (miRNAs) were not recognized as potential disease biomarkers until recently because of the rapid advance of sequencing technologies^2,3,4. The apoptosis and necrosis of tumor tissues can lead to release of cell-free DNAs (cfDNAs) into the circulating system⁵; these cfDNAs contain crucial genetic and epigenetic information for early diagnosis if sensitive and accurate methods can be developed.Human hepatocellular cancer, one of the most lethal cancers, is characterized by progressive accumulation of epigenetic changes⁶, among which hypermethylation of cancer-associated DNA offers distinct markers for diagnosis. DNA methylation patterns could change throughout the cancer development stages. If the same DNA methylation changes could be monitored in cfDNA released by tumor one could trace the emergence of the cancer, monitor the progression, and predict effects of treatments. Despite these advantages, current cfDNA detection is significantly hampered by the lack of sensitivity because only a very small amount of cfDNA could be obtained from plasma and serum. cfDNA is also heavily fragmented (between 200∼400 bp), adding additional challenges.Faced with these challenges, Wen et al.⁷ invent methylated CpG tandems amplification and sequencing (MCTA-Seq), a method that takes advantage of the fact that CpG tandems are highly enriched in the CpG island-containing promoters of human genome. These CpGs are typically unmethylated but tend to gain hypermethylation in hepatocellular carcinoma (HCC)⁶. The cfDNAs released into circulation carry the same hypermethylation patterns, thereby providing accurate information of the presence of HCC in patients. In their new method, cfDNA is treated with bisulfite, during which non-methylated C (cytosine) is converted to U (uracil) while methylated C remains unaffected. They then use a pair of primers to specifically amplify DNA loci that contain hypermethylated CGCGCGG, a sequence frequently presented in CpG islands and tend to be methylated in cancer tissues. The focus on the CGCGCGG-containing loci may miss other potential markers; however, it offers the sensitivity required for methylation detection in cfDNA. Validation data of MCTA-Seq shows that it is highly reproducible and sensitive, with the detection limit down to as low as 7.5 pg (∼2.5 haploid genome equivalents). Existing biomarkers that are frequently hypermethylated in human cancers⁸, such as VIM, SEPT9, NDRG2 and RASSF1⁸, could be detected with high sensitivity by using MCTA-Seq. The method, although limited by the requirement of the CGCGCGG sequence content, is genome-wide and offers sufficient information about CpG island methylation changes in HCC.Wen et al. applied the new method to detect tumor-specific CGI methylation with plasma samples from HCC patients, cirrhosis patients, and normal individuals. Two types of biomarkers have been identified for early stage HCC diagnosis (Figure 1). Type I markers possess significantly higher methylated CGIs than cancer-free individuals. Type II markers are tissue-specifically methylated CGIs, which tend to be restricted to liver cells under normal circumstances but are released into the blood when malignance occurs. Type II markers dominate in the cfDNA at early stage of HCCs, making them sensitive signs of tumor emergence.Open in a separate windowFigure 1Hypermethylated cfDNA released into the blood can be detected with a new method. Cell-free DNA-containing hypermethylated CpG islands (mCGIs) circulating in the blood of heptocellular carcinoma patients can be detected for early diagnosis. These marker DNAs are released by either tumor cells undergoing apoptosis or necrosis (type I) or adjacent non-cancerous cells affected by tumor growth (type II).The new method and the use of marker combination shown by Wen et al. provide a new strategy for DNA methylation detection from cfDNA. It may have widely applicable potential not only in HCC but also a cohort of other cancer types.     

Heritabilities and quantitative trait loci for blood gases and blood pH in swine

Maintaining pH and blood gases in a narrow range is essential to sustain normal biochemical reactions. Decreased oxygenation, poor tissue perfusion, disturbance to CO₂ expiration, and shortage of HCO₃⁻ can lead to metabolic acidosis. This is a common situation in swine, and originates from a broad range of medical conditions. pH and blood gases appear to be under genetic control, and populations with physiological traits closer to the pathological thresholds may be more susceptible to developing pathological conditions. However, little is known about the genetic basis of such traits. We have therefore estimated phenotypic and genetic variability and identified quantitative trait loci (QTL) for pH and blood gases in blood samples from 139 F₂ pigs from the Meishan/Pietrain family. Samples were taken before and after challenge with Sarcocystis miescheriana , a protozoan parasite of muscle. Twenty-seven QTL influencing pH and blood gases were identified on nine chromosomes. Five of the QTL were significant on a genome-wide level; 22 QTL were significant on a chromosome-wide level. QTL for pH-associated traits have been mapped to SSC3, 18 and X. QTL associated with CO₂ have been detected on SSC6, 7, 8 and 9, and QTL associated with O₂ on SSC2 and SSC8. QTL showed specific health/disease patterns that were related to the physiological state of the pigs from day 0, to acute disease (day 14), convalescence (day 28) and chronic disease (day 42). The results demonstrate that pH and blood gases are influenced by multiple chromosomal areas, each with relatively small effects.