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[Mechanism of watershed soil erosion control by vegetation].

From the view of hydrodynamics, this paper studied the acting mechanism of tree, grass and forest litter on slope runoff velocity and kinetic energy. The results showed that slope runoff head loss was related to slope gradient, forest density, net rainfall intensity and slope length. The relationship of water head loss with the distance among trees and the diameter at the ground of tree was Eoc (D/b)4/3. The grass on slope turned to be curved with s flowing, and thus, increased the bottom resistance of flow, and reduced the shearing stress of soil surface. Therefore, silt-carrying capacity decreased dramatically. The analysis of actually measured materials of each rainfall, runoff and sediment, and the comparison of Qiaozi eastern gully and Qiaozi west gully in Tianshui city of Gansu Province showed that under same precipitation condition, the runoff, sediment yield, flood peak discharge and maximum sediment transport rate in treated watershed was less than those in untreated watershed, suggesting that vegetation was obviously beneficial to water reservation and water and soil conservation.

Conservation of Natural Resources↗

Intersegmental elbow joint load during pushup.

Intersegmental loading pattern on the elbow joint during a push-up exercise was investigated. Electromagnetic motion sensors and a piezoelectric force plate were used to simultaneously record upper extremity motion and forces on nine healthy male subjects during push-ups in six different hand positions. Peak axial forces exerted on the elbow joint averaged 45 percent of the body weight. Peak torque to produce elbow flexion was 2305.9 N-cm, or 56 percent of maximal isometric extensor torque. The results of this analysis give insight to the biomechanics of a normal elbow and to its load carrying capacity.

Adult↗

New method of tracing blood hemoglobin concentration to hematocrit ratio for monitoring plasma dilution and osmotic origin shifts in blood.

Blood hemoglobin concentration and hematocrit are probably the most widely used parameters for outpatient and inpatient examination. In addition to their inherent significance for evaluation of blood viscosity and oxygen carrying capacity, these parameters are traditionally used as tracers of plasma dilution. Blood test derived results are conventionally recorded on multiple pages in patient's medical records making dynamical investigations tedious and time-consuming. In addition, research results describing plasma dilution by means of hemoglobin or hematocrit are presented in a clinically unpractical way. A new method, referred to as HBS Graphics (patent pending--USA serial # 60/712809) is introduced for the first time in this article. This method of evaluation of dynamical hemoglobin concentration, hematocrit and mean corpuscular hemoglobin concentration value deploys interfering parameter shifts for the evaluation of plasma dilution in relation to osmotic dynamics. The HBS Graphics complements two coordinate systems--hemoglobin concentration and hematocrit--with incorporated mean corpuscular hemoglobin concentration value specific trends referred to as radiating lines. Isosmotic plasma dilution and erythrocyte volume shifts follow radiating lines, while osmotic shifts induce intertrend shifts. This article also reviews other methods of tracing plasma dilution by means of blood hemoglobin concentration and hematocrit dynamics.

Blood Volume Determination↗

A study of placental umbilical cord whole blood transfusion in 72 patients with anemia and emaciation in the background of cancer.

In the under-resourced world, transfusion to advanced oncological patients involves two major problems, i.e., (a) transfusion transmitted disease, and (b) infrastructural deficiency. Many hospitals cannot cope with the specialized requirements of immunocompromised cancer victims, for instance, leucoreduction, selective apheresis, irradiation of the blood, viral inactivation of the blood by solvent and/or detergent treatment or photochemical inactivation using psoralen or long wavelength ultraviolet light and cytomegalovirus safe blood. The exorbitant cost of red blood cell (RBC) substitutes like hemoglobin-based oxygen carriers or perflurocarbon emulsions, liposome encapsulated hemoglobin, is simply unacceptable for an average oncological patient in the developing world. Moreover, it should be underscored that none of the total blood functions are replaced by any available so-called blood substitute, the primary function of which is oxygen delivery and volume expansion only. A more accurate term should be red cell substitute. Cord blood, because of its rich mix of fetal and adult hemoglobin, platelet and white blood cell (WBC) count, and plasma filled with cytokine and growth factors--as well as its hypoantigenic nature and altered metabolic profile--has all the potential of a real and safe alternative to adult blood during emergencies or any etiology of blood loss. In the present series, the collection of cord blood varied from 54 ml-128 ml, mean 82 ml +/- 7.6 ml SD; mean packed cell volume 48 +/- 4.1% SD; mean percent hemoglobin concentration 16.4 g/dl +/- 1.6 g/dl SD. Not a single case of immunological or non immunological reaction has been encountered so far after transfusion of cord blood to cancer patients with percent of hemoglobin 8 g/dl or less. It appears that the medical fraternity can safely use this precious gift of nature-- which is free from infection, hypoantigenic with altered metabolic profile, filled with growth factors and cytokine-filled plasma, and has the potential of a higher oxygen carrying capacity than adult blood--as an emergency source of blood for the management of advanced cancer cases with anemia.

Adolescent↗

Control and prevention of rabies in animals: paradigm shifts.

Animal management is the keystone of any modern programme for the prevention and control of rabies. Historically, "animal control" for local elimination of disease was largely equated with population reduction. However, with relatively few exceptions, culling alone has not led to effective control of rabies. In most documented examples of effective control of rabies in the 20th century, an integrated management approach was used that included public education, responsible stewardship of animal populations, manipulation of the population carrying capacity of the local habitat, and vaccination strategies. Globally, the greatest burden on human health that is attributable to this zoonosis is caused by uncontrolled rabies in dogs. Where political willingness, biomedical infrastructure, and economic stability permit the sustained use of control measures (e.g. stray animal removal and mandatory parenteral vaccination), canine rabies has been significantly suppressed and even eliminated over large geographical areas. Examples include many island nations, most of North America, Europe, and increasingly in South America. Despite the effectiveness of such proven control techniques, however, their implementation in parts of Asia, Africa, and elsewhere has been limited, primarily because of a lack of dedicated resources and intersectoral cooperation, and also because of the burden of high-density populations of dogs. Implementation is often complicated by cultural and social factors, e.g. reluctance to cull apparently ownerless, nuisance animals that are suspected to have been exposed to rabies, partly on the basis of religious beliefs). Attempts to modify animal fertility (such as the encouragement of voluntary spay-neuter programmes or individual chemical contraception, and the extension of such actions to animals in the community) may provide ancillary support in line with other traditional methods of control of canine rabies. With the identification of complex situations in which wildlife rabies persists despite the elimination of canine rabies, e.g. in North America and Europe, cats can pose a significant public health risk requiring consideration of alternative approaches. In any model system, the threat of translocation of infected animals, unintentional or otherwise, provides a strong rationale for the creation of barriers to prevent reintroduction or exacerbation of the disease, and the maintenance of a minimum body of expertise related to surveillance, diagnosis, and the enactment of mitigating measures. While control activities have traditionally focused upon certain Carnivora species, bats represent another worldwide rabies reservoir. Indiscriminate killing of bats and destruction of roosts was once the norm, but such activities are not sanctioned by reputable organizations today. Even vampire bats, responsible for substantial effects on health and agricultural losses in the New World (Mexico to Argentina), should be targeted only by specific control applications, rather than by more widespread, unconventional, non-specific methodology. Bats should be excluded from human living quarters. Implementing measures to prevent bats from gaining access to homes should occur at an appropriate time when the bats are absent, especially to avoid sealing the non-flying young within a building. Although great progress has been made during the past four decades in the induction of herd immunity among free-ranging carnivores via oral vaccination against rabies, similar novel solutions have not been readily applied to bat populations. Given these challenges, new paradigm shifts are eagerly anticipated as additional biotechnological applications (including contraceptives and anticoagulants) are developed to deal with domestic animals and wildlife.

Animals↗

Gender differences in hemorheological parameters of coronary artery disease patients.

Plasma fibrinogen concentration, plasma and whole blood viscosity (WBV) are independent risk factors of coronary artery disease (CAD). Fibrinogen seems to be a relatively stronger risk factor for women than for men, but men are more endangered by higher hematocrit (Hct) and WBV than women are. We have previously reported that a theoretically optimal Hct value can be determined using Hct/WBV ratio in healthy subjects, hyperlipidemic and Raynaud's disease patients. Our aim was to examine whether Hct/WBV ratio is differently correlated with Hct in men and women with proven CAD. In a retrospective study we analysed the hemorheological data of 162 CAD outpatients (107 men and 55 women). Coronary angiography, echocardiography and impedance cardiography were performed. Hemorheological parameters (Hct, fibrinogen level, plasma viscosity, WBV), blood picture, serum lipid concentrations were determined and Hct/WBV ratio was calculated. Mean ages of male and female patients were similar (54.9 and 55.4 years, respectively), but men had significantly higher coronary angiography score than women. Mean left ventricular ejection fraction, stroke volume index and cardiac index showed no significant differences in men and women. Similarly, lipid concentrations, fibrinogen levels and plasma viscosities demonstrated no statistical differences. However, Hct, WBV and Hct/WBV ratios were significantly higher in male than in female patients (p < 0.00001; p < 0.00001 and p < 0.005, respectively). The most striking gender difference was found in the correlation between Hct/WBV ratio and cardiac index. Men older than 56 years showed negative, women positive correlation (r = -0.485, p = 0.01; r = 0.468, p = 0.006, respectively). This study demonstrates that Hct/WBV ratio as a rheological oxygen carrying capacity parameter is positively correlated with the cardiac index as it can be expected. However, the correlation is negative in elder men indicating an unhealthy relation between hemodynamic and hemorheologic parameters.

Aged↗

Liposome-embedded-heme as a totally artificial oxygen carrier.

To produce a totally artificial oxygen carrying substance, a synthetic iron-porphyrin (heme) complex that is analogous to the oxygen binding site (protoheme) of hemoglobin was embedded in the phospholipid bilayer of a liposome. The O2 carrying capacity of this liposome-embedded-heme (L/H) was examined by exchange transfusions in beagles. Six beagles were divided into two groups. In Group I, 15 ml/kg of blood was removed, and the same amount of L/H solution was injected intravenously. In Group II, 30 ml/kg of blood was withdrawn, and the same amount of the L/H solution was injected intravenously. The mean L/H concentration in the blood was 0.9 mM in Group I and 1.5 mM in Group II. The oxygen volume transported by 1 mM of the L/H at 1 L/min of cardiac output in Groups I and II were 15 and 17 ml/mM.L.min, respectively. The oxygen volume consumed from 1 mM of the L/H at 1 L/min of cardiac output in Groups I and II were 7.7 and 8.3 ml/mM.L.min, respectively. O2 volume transported by the L/H in Groups I and II were 8 and 15%, respectively. O2 volume consumed from the L/H in Groups I and II were 12 and 24%, respectively. Thus, this liposome-embedded-heme has the ability to combine with oxygen, to transport it to the tissue, and to release it in the tissue. The oxygen volumes transported by and consumed from the L/H were proportional to the L/H concentration in the blood.

Animals↗

Nonencapsulated hemoglobin-based red blood cell substitutes: an updated view.

The characteristics and properties of the nonencapsulated hemoglobin (Hb)-based materials which have been used as substitutes for red blood cells are reviewed. The chemical and physical criteria such as oxygen dissociation, oxygen carrying capacity, antigenicity, viscosity, and circulatory retention time are described. The critical issue of Hb purity assurance testing is examined. The methods of the analyses which should be used to evaluate the lipid purity, endotoxin levels, and protein profile of Hb solutions are described. Additionally, the various approaches to Hb isolation, purification, and production are examined.

Animals↗

Transfusion in the newborn.

Transfusion, either with whole blood or blood components is frequently needed in the neonatal intensive care. Certain aspects are very important to consider. Citrated blood is preferred to heparinized blood. Transfusion must be rational, either with whole blood or blood components. Whole blood is only indicated for repletion of blood volume, exchange transfusion and certain cases in which no blood component needed is available. To improve oxygen carrying capacity, to stop bleeding due to coagulation defect, thrombocytopenic bleeding due to depressed platelets production and to counter gram negative septicemia, blood component is indicated to obtain optimal effects with minimal side effects.

Blood Component Transfusion↗

Identification of transferrin as a progression factor for ML-1 human myeloblastic leukemia cell differentiation.

We have previously demonstrated (Guan X.-P., Hromchak, R. A., and Bloch, A. (1989) Cancer Commun. 1, 111-115) that ML-1 human myeloblastic leukemia cells differentiate to monocyte/macrophage-like cells by the sequential action of competence and progression factors. Tumor necrosis factor-alpha, transforming growth factor-beta, and the phorbol ester tetradecanoylphorbol acetate were found to induce competence, whereas a 77-kDa glycoprotein (DF77) isolated from mitogen-stimulated human leukocyte-conditioned medium initiated progression. In this communication we show DF77 to be an isoform of human transferrin. Hemin or soluble iron complexes did not induce differentiation progression, suggesting that the participation of transferrin in ML-1 cell differentiation may not be related to its iron-carrying capacity.

Amino Acid Sequence↗

The hemodynamic response to hemorrhage in tumor-bearing animals.

Tumor-bearing rats submitted to hypovolemia have higher mortality rates than have non-tumor-bearing control rats. To determine the mechanisms underlying this sensitivity to hemorrhage, we studied Fischer-344 rats with subcutaneous methylcholanthrene-induced sarcoma (tumor burden, 10% body weight) to determine hematologic and blood volume alterations. Subsequently we used the same animal model in an unanesthetized condition to determine the sensitivity to hemorrhage and resuscitation, as well as vascular responsiveness to vasoactive agents. The rats were separated into two groups: control and tumor-bearing rats (TBR). Sensitivity to hemorrhage and resuscitation was determined by bleeding the conscious rats (15 ml/kg) and resuscitating them with 0.9% NaCl (45 ml/kg). Vascular responsiveness was determined after injection of varying doses of phenylephrine and nitroglycerin, with continuous measurement of mean arterial pressure (MAP). Rate of increase of MAP, maximum MAP, relative increase in MAP (maximum minus baseline), rate of recovery toward baseline MAP, and duration of the response were determined. There was a significant anemia in TBR, but blood volume was similar in both groups. Baseline MAP was significantly higher in control rats (125.3 +/- 8.1 mm Hg) compared with TBR (107.5 +/- 6.0 mm Hg). After hemorrhage, MAP in TBR reached significantly lower levels than in control rats. In addition, after saline resuscitation, MAP in TBR did not return to baseline levels, whereas MAP in control rats returned to prehemorrhage MAP. With nitroglycerin, MAP decreased to lower levels in TBR than in control rats. With phenylephrine, the maximum MAP reached was significantly higher, and the response to phenylephrine was maintained for a significantly longer period in control rats compared with TBR. We conclude that TBR are more sensitive to hypovolemic events in association with decreased oxygen-carrying capacity, profound hypotension, and altered overall vascular responsiveness to sympathetic stimuli.

Angiotensin II↗

Biomechanics of fracture risk prediction of the hip and spine by quantitative computed tomography.

In this review, we have made use of some simple engineering concepts to summarize current efforts relating QCT measures to bone density and strength. From a variety of in vitro experiments on cadaveric vertebrae and femora, it is evident that both apparent and ash densities are strong linear functions of QCT measures, with coefficients of determination ranging from 0.49 to 0.90 and relative errors from 44.9% to 7.1%. QCT data also can be used (with somewhat less confidence) to determine the compressive modulus (R2s from 0.36 to 0.68, relative errors from 45.0% to 35.5%) and compressive strength (R2s from 0.58 to 0.70, relative errors from 56.5% to 39.9%) of trabecular bone from the proximal femur and vertebral body. In cortical bone, material properties are only correlated weakly with QCT measures. Experiments designed to relate QCT data to failure loads for the proximal femur and vertebral body have been remarkably successful. Coefficients of determination have ranged from 0.32 to 0.93, with relative errors from 31.1% to 13.9%. However, when the in vitro failure loads determined in these experiments are compared against available estimates of in vivo loads on the spine and hip, it is apparent, at least in the elderly, that in vivo loads are relatively close to those that cause fracture in vitro. To assess the possibility of developing QCT-based clinical predictors of fracture risk for individual patients, we have introduced the concept factor of risk often used in engineering design to account for uncertainties in estimates of service loads and component strength. The factor of risk for a particular loading condition is defined as the ratio of expected service loads to the known failure loads. To extend this concept to densitometric fracture risk prediction in vivo, it is important to recognize that densitometric data must not only be used to predict the ultimate load carrying capacity of the region of interest, but that this ultimate load must then be compared to the forces expected in vivo under comparable loading conditions. One difficulty with this approach is that little is known about the in vivo forces that are associated with atraumatic age-related fractures of the hip and vertebrae and even less about the forces applied to the hip and spine during traumatic events such as falls. However, from available estimates of in vivo loads during bending and lifting, it is apparent that in the elderly, factors of risk for the spine can easily approach 1.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗

Effect of red blood cell rigidity on tumor blood flow: increase in viscous resistance during hyperglycemia.

Elevated glucose level and low pH have been shown to increase red blood cell (RBC) rigidity. This increased rigidity has been proposed as one factor which mediates the tumor blood flow (TBF) reduction during hyperglycemia by (a) causing RBC entrapment and hence increasing geometric resistance and (b) increasing viscous resistance to blood flow. However, due to the inability to measure these resistances in vivo in tumors directly, the relative contribution of RBC rigidity in TBF reduction has not been quantified. In the present study, blood flow resistance was measured in "tissue-isolated" mammary adenocarcinoma R3230AC perfused ex vivo with (a) normally deformable, (b) glutaraldehyde-hardened, and (c) glucose-incubated RBC suspensions. Flow resistance measured during tumor perfusion with Krebs-Henseleit buffer prior to and following perfusion with the glutaraldehyde-hardened RBC suspensions showed no significant change, suggesting constant geometric resistance and lack of RBC entrapment. Instead, our measurements indicated increased viscous resistance with loss of deformability due to glutaraldehyde and glucose incubation even though glucose incubation did not significantly alter the apparent blood viscosity measured in vitro. Thus, the TBF reduction during hyperglycemia may be due to subtle changes in RBC deformability. These results suggest the development of strategies to increase the delivery of drugs or oxygen must take into account any changes in intratumor viscous resistance. For example, the increase in the oxygen-carrying capacity of blood using RBC transfusion or fluorocarbon emulsions may be offset by the increase in viscous resistance and the corresponding reduction in TBF.

Adenocarcinoma↗

Fluid therapy in the PACU.

The goal of fluid therapy in the PACU setting is the restoration of blood volume and tissue perfusion. Choosing the type of fluid infusion depends on the preoperative, intraoperative, and postoperative condition of the patient. An understanding of the functional fluid compartments, the composition of body fluids and commercially available fluids, and the steps to evaluate fluid depletion allow one to determine the fluid needs of the patient. The orderly and expedient evaluation of fluid status of the postoperative patient involves the assessment of volume status, concentration status, composition status, and signs and symptoms of inadequate tissue perfusion. Recovery after surgery is a dynamic process, and fluid reassessment should be conducted periodically. Fluid challenges may be necessary in the hypovolemic patient or in patients with clear signs and symptoms of end-organ hypoperfusion. Weil and Rackow and Shoemaker provide useful approaches to fluid challenge guided by CVP and PAP monitoring. The decision of whether to use crystalloids or colloids for fluid resuscitation is complex, controversial, often determined by personal preference and concern over expense, and may be inconsequential as long as fluids are infused appropriate to the needs of the patient. There are disadvantages and advantages to both crystalloid and colloid fluid administration. As with any therapeutic intervention, there are complications with fluid administration, congestive heart failure and pulmonary edema being of more immediate concern. Finally, blood components are colloid-type solutions that should be reserved for specific patient problems. Red blood cells are indicated to increase oxygen-carrying capacity in patients with anemia. Platelets are used to treat bleeding associated with deficiencies in platelet number or function. Fresh frozen plasma is transfused to increase clotting factor levels in patients with demonstrated deficiency. A good understanding of fluid types available, of a systematic approach to evaluating fluid depletion, and of the indications for blood component therapy will allow one to make appropriate decisions when implementing fluid therapy in the PACU.

Blood Transfusion↗

Malaria as anthropo-ecosystem (MAES): Part V. Self-regulation and stability of MAES.

In biological ecosystems, population tends to fluctuate above or below asymptotic level or the 'carrying capacity'. Self-regulation is achieved by extrinsic, that is, environmental limiting factors and intrinsic, that is, physiological and genetic factors. In Malaria Anthropo-Ecosystem (MAES) which is much more intricate and complex system, Plasmodium being endoparasite is required not only to interact with intrinsic factors of its vertebrate and invertebrate host but also to regulate itself to environmental factors to which its both the hosts are subjected. Attempt has been made to provide, on the basis of present knowledge, the probable explanation of self-regulatory mechanisms from molecular, cell, organ/organism, population/community levels of vertebrate and invertebrate hosts which give stability to MAES as a whole system.

Animals↗

Tumor radiocurability: relationship to intrinsic tumor heterogeneity and to the tumor bed effect.

Recent in vitro clonogenic assays of cells from human head and neck carcinomas recurring after fractionated irradiation showed that the mean radiation resistance was significantly greater than that of cells from unirradiated head and neck cancers. Analysis of these data using the linear-quadratic formalism of radiation inactivation indicates that such increased resistance was associated with a large decrease in the parameter describing cell killing by one-hit processes, while the parameter describing cell inactivation by two-hit processes was unchanged. These data suggest that head and neck carcinomas contained intrinsically radioresistant tumor subpopulations that were selected for during the fractionated radiation therapy. Consequently, we have generated a model of how the phenomenon of clonal intraneoplastic diversity might be related to the selection of radioresistant sub-populations. There is, however, an additional major modulating factor which may impact upon the proposed selection process, known as the tumor bed effect. This effect refers to the fact that solid tumors grow at slower rates and to decreased carrying capacities in radiation-damaged normal tissue stroma. We hypothesize that the tumor bed effect is a reflection of an altered, hostile microenvironment within which competition among neoplastic subpopulations for limited resources is increased. This then produces a situation leading to extinction of minority subpopulations within heterogeneous neoplasms, regardless of whether such populations are radioresistant. The final result of these selection/extinction processes will be dependent upon total dose, dose per fraction, overall time, and the initial partial volume percentages of radioresistant subpopulations.

Flow Cytometry↗

Transfusion and coagulation: an overview and recent advances in practice modalities. Part I: Blood banking and transfusion practices.

Increased sophistication in blood banking and transfusion practice has opened new directions in management of red cell mass and coagulation. The current trend in practice is to avoid absolute hemoglobin or hematocrit values, and to employ physiologic parameters to determine the need for transfusion. For red cell mass, those parameters include use of oximetry, particularly venous oximetry, calculation of oxygen-carrying capacity using cardiac outputs and arterial oxygen saturation, and the ability of each patient to increase cardiac output and/or maintain suitable arterial pressure with hemodilution. More exacting assessment of the coagulation profile, along with evidence that supports the critical circulating platelet and fibrinogen levels, permits judicious use of blood components.

Blood Banks↗

[The structuro-functional heterogeneity of an artificial oxygen carrier based on hemoglobin].

Pyridoxylated polymerized hemoglobin (PP-Hb) was fractionated by the method of high pressure liquid chromatography, Molecular weight distribution, oxygen carrying capacity and antigenic characteristics of separated fractions have been investigated. It was demonstrated that a fraction may be separated from the crude PP-Hb, which is greatly homogeneous if structural and functional characteristics are concerned, and also optimal according to the parameters investigated. So, by a corresponding fractionation method it is possible to overcome the main limitation for use of PP-Hb as an artificial oxygen carrier--its heterogeneity.

Blood Substitutes↗