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PubMed2000

Contrast Agents for Cardiac Angiography: Osmolality and Contrast Complications.

Radiographic contrast agents have undergone a tremendous evolution over the past several decades. The creation of contrast agents with greater iodine carrying capacity and lower osmolality has improved imaging quality and reduced complications, including nausea, vomiting, congestive heart failure, and cardiac rhythm abnormalities. Whether differences exist among agents in terms of thrombotic complications remains controversial. Several characteristics including potential complications, toxicity, and cost must factor into the decision to use a particular contrast agent in cardiac procedures.

Journal Article↗
PubMed2000

Targeted synthetic gene delivery vectors.

Synthetic gene delivery vehicles have made significant progress in the past decade in demonstrating strong potential for targeted delivery to specific cells, low toxicity and immunogenicity and large carrying capacity. However, significant advances must still be made to increase the efficiency of both polymer and lipid vehicles. Furthermore, techniques to generate more effective targeting moieties for a variety of cell types, as well as means to consistently assemble vectors containing these targeting ligands, are areas for further improvement. This review focuses on significant recent advances in generating a number of novel targeted vectors, and discusses progress in the development of new genetic and chemical systems to enhance the targeting, assembly and biocompatibility of synthetic vectors.

Animals↗
PubMed2001

[Biomechanical studies on two thoracolumbar implants in cadaveric spine].

The aim of these studies was to evaluate the biomechanical characteristics of two devices and provide information for clinical choice. In vitro cadaveric spine testing which consisted of the stability test and the yield strength test was performed. In hemicorpectomy model, the AF was stiffer than the Kaneda in flexion, extension and left lateral bending (P < 0.01). In total corpectomy model, the AF was stiffer than the Kaneda in flexion, left lateral bending and axial rotation (P < 0.01). The average values of yield strength(M) for the Kaneda, the AF and the intact were 477.3 kg, 544.4 kg and 493.6 kg resectively. The stability of the AF is superior to that of the Kaneda. In total corpectomy, the Kaneda is significantly unstable in axial rotation. Both devices restore effectively load carrying capacity of the spine.

Adult↗
PubMed2001

A study report of 174 units of placental umbilical cord whole blood transfusion in 62 patients as a rich source of fetal hemoglobin supply in different indications of blood transfusion.

BACKGROUND: In the animal kingdom, even herbivorous animals swallow the placenta after the birth of the baby (for example, the cow). In the human system, we do not know about the proper utilization of the placenta and membranes although there are suggestions regarding this on the basis of research on placental umbilical cord blood stem cells as an alternative to bone marrow transplantation. In this present series of placental umbilical cord whole blood transfusions, we wanted to examine the safety aspect of other components of cord blood transfusion, e.g., fetal RBC, growth factors and cytokine filled plasma, etc., in different indications of blood transfusion, from the pediatric to the geriatric age group, in malignant and non-malignant disorders affecting our patients. METHODS: One hundred and seventy-four units of umbilical cord whole blood were collected aseptically from the umbilical vein after caesarean section in standard pediatric blood transfusion bags, after the removal of the baby from the operative field and after confirming the stable condition of the mother. The volume of cord blood varied from 50 ml to 140 ml with a mean of 86 ml+/-16 ml. RESULTS AND ANALYSIS: The cord blood was transfused immediately (within three days of collection) to 62 patients from nine years to 78 years of age, of whom 32 were suffering from varying stages and grades of malignancy from 1 April 1999 till date i.e., 11 Aug 2000, after obtaining adequate consent and following the precautions of standard blood transfusion protocol. The remaining 30 patients included patients suffering from thalassemia major, aplastic anemia, systemic lupus erythematosus, chronic renal failure, rheumatoid arthritis, ankylosing spondylitis and a geriatric group of patients with benign prostatic hypertrophy. All have tolerated the procedure without any immunological or non-immunological reactions. CONCLUSION: On the basis of our experience with 174 units of placental umbilical cord whole blood transfusion in malignant and non-malignant conditions (within three days of collection and preservation at 1-6 degrees C in a refrigerator), we are of the opinion that this is a safe transfusion protocol which takes advantage of the safety of nature's finest biological sieve, i.e., the placenta, as an alternative to adult whole blood transfusion. It also has the advantage of a higher oxygen carrying capacity of fetal hemoglobin in addition to many growth factors and other cytokine filled cord blood plasma along with its hypoantigenicity.

Adolescent↗
PubMed2001

Oxygen therapeutics--current concepts.

PURPOSE: In an effort to develop agents that enhance the oxygen-delivery capability of blood without the risks associated with allogeneic blood transfusions, several products are undergoing development and clinical trials. These oxygen transport agents can be divided into two main groups, perfluorocarbon (PFC) emulsions and modified hemoglobin solutions. SOURCE: Articles from the literature on the development and clinical trials of oxygen therapeutic agents were reviewed. PRINCIPAL FINDING: PFCs are synthetic fluorinated hydrocarbons that increase dissolved oxygen in the fluid phase of the blood without binding the oxygen molecule. They enhance oxygen delivery significantly and may be used to augment the technique of intraoperative autologous donation. Two PFC products have been tested in Phase III clinical trials. Hemoglobin-based oxygen carriers (HBOCs) are either cross-linked or microencapsulated hemoglobin molecules. Modification of the human hemoglobin molecule with intra- and inter-molecular cross-linking eliminates renal toxicity and improves the oxygen dissociation characteristics of the molecule. These modifications are necessary because stroma-free hemoglobin (Hb) does not release oxygen in the physiologic range and dissociates into dimers which can be rapidly filtered by the kidney, leading to renal toxicity. In addition to human Hb, bovine hemoglobin is another source of raw material for HBOC products. Recombinant human Hb has also been produced, using an E. coli expression system, for HBOC manufacturing. Four cross-linked hemoglobin products have been tested in Phase III clinical trials. CONCLUSION: While no product has yet been approved for clinical use, preliminary studies with oxygen therapeutics show promising results, with effective oxygen carrying capacity and acceptable side effect profiles. In the future, the formation of a hybrid product which combines the best features from several of the products currently undergoing development may yield the ideal oxygen therapeutic agent.

Aspirin↗
PubMed2001

Safety and efficacy of o-raffinose cross-linked human hemoglobin (Hemolink) in cardiac surgery.

PURPOSES: There are currently two major classes of oxygen therapeutics: hemoglobin based oxygen carriers (HBOCs) and synthetic perfluorocarbons (PFCs). This review focuses on the use of o-raffinose cross-linked human hemoglobin (Hb raffimer) in cardiac surgery. SOURCE: The literature on HBOCs was reviewed and the development and clinical trials on Hb raffimer were outlined. PRINCIPAL FINDING: The benefits of HBOCs include avoidance of known viruses, pathogens and cross-matching; increased stability and storage time; and efficient oxygen delivery to tissues. The limitations of HBOCs include binding the endogenous vasodilator, nitric oxide, thereby resulting in transient hypertension, esophageal dysfunction and abdominal discomfort. The short half-lives of these products makes them best suited to situations of acute anemia. Hb raffimer is prepared from outdated red blood cells, cross-linked with o-raffinose, a polyaldehyde obtained through the oxidation of the trisaccharide raffinose. The Hb is covalently cross-linked (beta-beta) within the 2,3 DPG binding pocket to form a stable 64 kDa tetramer. At this time, a total of over 500 patients have been enrolled and more than 300 patients have been treated with Hb raffimer. Preliminary analysis of data from recent Phase II & III clinical trials of Hb raffimer in routine coronary artery bypass grafting surgery suggest that the product is well tolerated and may facilitate avoidance of allogeneic blood product transfusion in this surgical setting. CONCLUSION: The converging evidence from clinical studies with HBOCs has demonstrated that these products have the potential to provide hemoglobin and oxygen carrying capacity to tissues in times of acute anemia during surgery. It is anticipated that Hb raffimer will be used to facilitate intraoperative autologous donation and emerge as an important alternative to allogeneic blood transfusion during cardiac surgery.

Cardiac Surgical Procedures↗
PubMed2001

Utilizing image processing techniques to compute herbivory.

Leafy spurge (Euphorbia esula L. sensu lato) is a perennial weed species common to the north-central United States and southern Canada. The plant is a foreign species toxic to cattle. Spurge infestation can reduce cattle carrying capacity by 50 to 75 percent [1]. University of Wyoming Entomology doctoral candidate Vonny Barlow is conducting research in the area of biological control of leafy spurge via the Aphthona nigriscutis Foudras flea beetle. He is addressing the question of variability within leafy spurge and its potential impact on flea beetle herbivory. One component of Barlow's research consists of measuring the herbivory of leafy spurge plant specimens after introducing adult beetles. Herbivory is the degree of consumption of the plant's leaves and was measured in two different manners. First, Barlow assigned each consumed plant specimen a visual rank from 1 to 5. Second, image processing techniques were applied to "before" and "after" images of each plant specimen in an attempt to more accurately quantify herbivory. Standardized techniques were used to acquire images before and after beetles were allowed to feed on plants for a period of 12 days. Matlab was used as the image processing tool. The image processing algorithm allowed the user to crop the portion of the "before" image containing only plant foliage. Then Matlab cropped the "after" image with the same dimensions, converted the images from RGB to grayscale. The grayscale image was converted to binary based on a user defined threshold value. Finally, herbivory was computed based on the number of black pixels in the "before" and "after" images. The image processing results were mixed. Although, this image processing technique depends on user input and non-ideal images, the data is useful to Barlow's research and offers insight into better imaging systems and processing algorithms.

Algorithms↗
PubMed2001

High viscosity plasma expanders: Volume restitution fluids for lowering the transfusion trigger.

Hemorheological studies lead to the axiom that high plasma viscosity is detrimental and that it is beneficial to lower blood viscosity, a precept embodied in the practice of hemodilution, where improved perfusion is attributed to the lowering of blood viscosity. Hemodilution is limited by the transfusion trigger, hemoglobin content of blood of about 7-8 g/dl, which indicates when further volume replacements must restore oxygen carrying capacity with red blood cells (RBC). However, oxygen consumption and delivery are not compromised upon passing this landmark. The reduced blood viscosity does not transmit adequate pressure to the capillaries, causing functional capillary density (FCD) to decrease, jeopardizing organ function through the inadequate extraction of products of metabolism from the tissue by the capillaries. Studies in hemorrhagic shock show that survival is primarily determined by the maintenance of FCD and secondarily by tissue oxygenation. FCD is maintained as hematocrit is reduced beyond the transfusion trigger by increasing plasma viscosity, which transmits systemic pressure to the capillaries and induces vasodilatation through the increased shear stress dependent release of vasodilators. Consequently the transfusion trigger is also a "viscosity trigger" indicating when blood and plasma viscosity are too low. In this condition increasing plasma viscosity is beneficial and extends the transfusion trigger reducing the use of blood transfusions.

Animals↗
PubMed2001

Advances in fluid resuscitation of hemorrhagic shock.

The optimal fluid for resuscitation in hemorrhagic shock would combine the volume expansion and oxygen-carrying capacity of blood without the need for cross-matching or the risk of disease transmission. Although the ideal fluid has yet to be discovered, current options are discussed in this review, including crystalloids, colloids, blood and blood substitutes. The future role of blood substitutes is not yet defined, but the potential advantages in trauma or elective surgery may prove to be enormous.

Blood Substitutes↗
PubMedDate not supplied

[Aerodynamic characteristics of the human right lung bronchial tree].

A new method of studying the aerodynamical characteristics of normal right bronchial tree in 17 natural preparations is described. The authors have found that 24 to 44 per cent of the total airflow entering the right main bronchus pass through the upper lobe bronchus, 9-26 per cent through the middle lobe bronchus and 38-56 per cent through the lower lobe bronchus. The data obtained show good agreement with the volume of the corresponding lobe expressed as percentage to the total right lung volume. Bronchial tree preparations differ greatly in their carrying capacities due to their corresponding aerodynamical resistances (+50% +25%). The relationship between resistance coefficient of the bronchial tree preparations and their geometrical parameters has been found.

Airway Resistance↗
PubMed1975

Intraoperative prebleeding in man: effect of colloid hemodilution on blood volume, lung water, hemodynamics, and oxygen transport.

The effects of acute normovolemic hemodilution on lung water, blood volume, hemodynamics, and oxygen transport were studied. The subjects were six patients undergoing major operations, with prebleeding and hemodilution under fluoroxene and nitrous oxide anesthesia. The menatocrit was reduced form 43 to 25 percent in one step, with simultaneous infusion of Plamanate and lactated Ringer's solution. Blood volume was expanded by 5 percent by the hemodilution. The major compensation was a striking rise in cardiac output to 161 percent. Systemic oxygen transport (CO times arterial O2 content) increased despite the marked fall in oxygen-carrying capacity, and the arteriovenous O2 content difference decreased. Lung water the aveolararterial (A-a) oxygen differences were reduced. The procedure was well tolerated by this group of selected patients and homologous blood utilization was reduced.

Adult↗
PubMedDate not supplied

Anterior ischemic optic neuropathy and dialysis: role of hypotension and anemia.

The pathogenesis of anterior ischemic optic neuropathy (AION) primarily involves interference with the posterior ciliary artery blood supply to the prelaminar optic nerve. Uremic patients often have coexisting pathology such as hypotension (decreased blood delivery), or hypertension, atherosclerosis (increased resistance to blood supply), and anemia (low blood oxygen carrying capacity), predisposing them to AION. We describe a 49-year-old patient on dialysis for many years. He had long-standing hypotension, worsened during each dialysis treatment. He awoke one morning at age 48 complaining of blurred vision in the left inferior field. Based on the clinical course, funduscopic and fluorangiographic examination and visual field defects, AION was diagnosed. Nine months after the loss of vision in the left eye, vision in the right eye became blurred and worsened over the next 24 hours. The diagnosis of AION in the right eye was made. At the last examination ten months later, the patient, still amaurotic, was given a very poor prognosis for further recovery of the visual defects. Surprisingly, very few cases of AION have been reported in chronic uremic patients on dialysis: to the best of our knowledge, only 12 including ours. Most of these cases share some features, including hypotension above all and anemia as common risk factors. Neither the type of dialysis treatment (hemo-, peritoneal dialysis) nor sex seem to have any influence on the occurrence of AION. Uremic children can be affected. What is striking in the three published pediatric cases is that they all had polycystic kidney disease. Treatment of AION in all 12 cases consisted of a combination of steroids, i.v. saline, blood transfusions and rhEpo. AION was more frequently bilateral and irreversible, ending in permanent amaurosis. In conclusion, this study aims to stress that most cases of AION occurring in chronic uremic patients on dialysis have some common features, including hypotension above all and anemia as common risk factors.

Anemia↗
PubMed2001

[Runoff loss ways of nutrients in non-irrigated farmland in Hefei outskirts].

Taking non-irrigated flatlands in Hefei outskirts as experiment observation areas, yellow brown soil as selected soil type, and < 3 degrees as ground slope, the time of runoff development, runoff quantities, and silt carrying capacity under different rainfall intensity were observed on the non-irrigated farmlands with different kinds of crops such as grain, oil, cotton and vegetables, and with different coverage for continuous 3 years. Based on the observation, water and soil samples were collected and analyzed. The results showed that the loss way of the surface soil and nutrients in non-irrigated flatlands was obviously different from that on the sloping fields and on the upland. Over 98% of available N, P, and K nutrient loss were run off by chemical erosion. Physical erosion was the main way of the surface soil and organic matter loss, and 96.14% of total organic loss was caused by physical erosion.

Ecology↗
PubMed2001

Myocardial ischemia. Monitoring to diagnose ischemia: how do I monitor therapy?

Diagnosis of myocardial ischemia requires integration of ECG, pulmonary artery pressures, and TEE data. ST depression of 1 mV or elevation of 2 mV remains the mainstay of diagnosis of ischemia. Increases of pulmonary artery pressures of 5 mm Hg are common but not reliably diagnostic of ischemia. Transesophageal echocardiography is the most sensitive monitor of ischemia, where the spectra of SWMA evolve. Diastolic dysfunction (elevations in LVEDP) is a more sensitive marker of ischemia, but requires measurement of several Doppler patterns. After diagnosis, treatment should include optimization of hemodynamics (beginning with beta-blockers and nitrates), anesthesia, and oxygen-carrying capacity (e.g., normothermia, oxygen saturation, hematocrit more than 28%).

Blood Pressure↗
PubMed1975

What is the mechanism of carbon monoxide toxicity?

The probable toxic action is CO is on the cellular respiration, in which CO competes with O2 for cytochrome a3. Our studies indicate that a relatively high concentration of COHb (50%) does not interfere with the O2-carrying capacity of the blood. The dissolved CO in plasma, which is necessary for CO to enter the tissue, probably occurs when the exchange takes place between alveolar air and the blood in the lungs. This would explain why the central nervous system could be impaired when COHb levels are below 10% and death could occur at 35%.

Aerospace Medicine↗
PubMed2001

Runaway social games, genetic cycles driven by alternative male and female strategies, and the origin of morphs.

Analysis of evolutionarily stable strategies (ESS) and decade-long field studies indicate that two color morphs of female side-blotched lizards exhibit density- and frequency-dependent strategies. Orange females are r-strategists: they lay large clutches of small progeny that are favored at low density. Conversely, yellow females are K-strategists: they lay small clutches of large progeny that are favored when carrying capacity is exceeded and the population crashes to low density. Interactions among three male morphs resembles a rock-paper-scissors (RPS) game. Fertilization success of males depends on frequency of neighboring morphs. Orange males usurp territory from blue neighbors and thereby mate with many females. However, orange males are vulnerable to cuckoldry by sneaky yellow males that mimic females. The yellow strategy is thwarted in turn by the mate-guarding strategy of blue. Sinervo and Lively (1996) developed a simple asexual model of the RPS game. Here, we model the dynamics of male and female morphs with one- and two-locus genetic models. Male and female games were considered in isolation and modeled as games that were genetically coupled by the same locus. Parameters for payoff matrices, which describe the force of frequency-dependent selection in ESS games, were estimated from free-ranging animals. Period of cycles in nature was 5 years for males and 2 years for females. Only the one locus model with three alleles (o, b, y) was capable of driving rapid cycles in male and female games. Furthermore, the o allele must be dominant to the y allele in females. Finally, the amplitude of male cycles was only reproduced in genetic models which allowed for irreversible plasticity of by genotypes, which is consistent with hormonally-induced changes that transform some males with yellow to dark blue. We also critique experimental designs that are necessary to detect density- and frequency-dependent selection in nature. Finally, runaway ESS games are discussed in the context of self-reinforcing genetic correlations that build and promote the formation of morphotypic variation.

Alleles↗
PubMedDate not supplied

[Problems in brain protection].

The main aim of intensive care in acute head injury and in the postoperative period is to prevent, detect, and revert a secondary neuronal injury. To maintain the optimum systemic and cerebrovascular functions can substantially promote this aim achievement. There are some new neuroprotective interventions that are currently under investigation. Although the major focus of recent cerebral protection researches has been on the development of receptor-specific drugs, this effort has resulted in better outcomes. At present, patients are well served by using more traditional techniques to prevent and treat cerebral ischemic events. Initial therapy should include interventions to improve cerebral perfusion and the oxygen-carrying capacity of blood. Once this is accomplished, measures should be made to monitor blood glucose concentrations and to treat fever. General anesthetic choice may be of great importance in monitoring intracranial pressure and seizure activity. However, if direct cerebral protection is desired, a barbiturate should be the anesthetic of choice. All these measures should increase the chance of patients to neurologically recover following hypoxia and ischemia.

Blood Glucose↗
PubMed2002

Workshop 2 (synthesis): driving forces and incentives for change towards sustainable water development.

Water is a key resource in attaining sustainability--in social and economic development as well as in the long-term carrying capacity of the planet's life support systems, but consensus on the meaning and priority of these terms is still needed. Amongst the key points identified for water professionals: it is necessary to challenge compartmentalisation in water policy and management; water management strategies must focus clearly on the interdependence of the environment and socio-economic development; water professionals have a key role but must package the information and insight they can provide in a way that is attractive to intended recipients such as policy makers.

Commerce↗