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Results for “Carrying Capacity”

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At least 37 records · Page 2Linked to original sources
PubMed2001

Assessment of newly developed perfluorocarbon emulsion: oxygen carrying capacity as the blood substitute in vivo.

This study provides the evaluation of oxygen carrying capacity of the novel perfluorocarbon emulsion (Neo-PFC) produced by the new emulsifying technology named High Pressure Process. For the performance comparison of oxygen carrying abilities of Neo-PFC and a representative PFC emulsion, the oxidation states of cerebral tissues in substituted animals were measured by near-infrared spectrometry. After the 70% exchange transfusion of whole blood of rats by Neo-PFC and Fluosol-DA, fractional inspired oxygen (FiO2) was gradually decreased from 100% to 0%. As the control experiments, the blood was substituted by Krebs Ringer bicarbonate buffer containing 3% BSA. When the blood of rats was substituted by Neo-PFC, Cyt. ox., a terminal enzyme in mitochondrial respiratory chain maintained fully oxidized state with FiO2 values between 100 to 40%. By contrast, in the models substituted by Fluosol-DA and BSA-buffer. Cyt. ox. was gradually reduced with FiO2 values below 60% and 80%, respectively. This specific advantage of Neo-PFC was explained by its higher oxygen solubility in arterial blood. The novel PFC emulsion prepared by the new emulsifying technology is a potential basis for blood substitutes.

Animals↗
PubMed1988

Experimental evaluation of the antibiotic carrying capacity of a muscle flap into a fibrotic cavity.

A study was undertaken to determine the antibiotic carrying capacity of a transferred muscle flap into a fibrotic cavity using a tissue cage model in rabbits. Blood and chamber fluid antibiotic levels were determined after intramuscular hindlimb gentamicin injection up to 56 days following muscle transfer. This study suggests that muscle flaps increase the concentration of antibiotics that can be achieved within a fibrotic cavity. The measurable peak level decreases with time, probably due to increased scarring around the muscle. This model should enable the study of many different classes of antibiotics with different protein binding and other administration schedules using multiple timed doses or a combination of agents.

Animals↗
PubMed1994

Subsistence ecology and carrying capacity in two Papua New Guinea populations.

This article examines the mechanisms of subsistence adaptation of two Papua New Guinea populations, the Metroxylon sago-depending lowland Gidra and the taro-monoculture Mountain Ok, surviving in low population densities of 0.5 and 1.4 persons per km2. Observation of the groups' land use systems strongly suggests that their population densities have not been far below the carrying capacity, although the territory of each population is markedly heterogeneous. Both groups have maintained their sustainable food production not only for resource management but also for survival at a population level, either expanding their territory or changing the sustainable level in tandem with changes of subsistence system.

Adult↗
PubMed1978

[The load carrying capacity of the teeth of the human jaw].

Three different methods of measurement are used to objectify the maximum load-carrying capacity of individual pairs of teeth. For these, use is made of a mechanical, electric, and elastooptic measuring instrument. The measurement results obtained using the mechanical and electric instruments are largely identical. They are in the neighborhood of 20 kgf and 50 kgf for incisors and molars, respectively, of male subjects. The results obtained for female test subjects were lower by an average of 10 kgf. The mechanical and electric measuring instruments may be used for the examination of a larger number of test subjects as well as under pathological conditions.

Dental Stress Analysis↗
PubMed1982

[Experimental investigations of the axial load carrying capacity of the long bones using Steinmann-pins (author's transl)].

This paper reports the results of experimental investigations of the axial load carrying capacity of the long human bones. These investigations were conducted using a commercial high precision materials testing machine. Force-transmission was effected by Steinmann-pins or screws drilled transversely into the various long bones. The measured loading capacities are reported for various sections of the long bones. Their importance in regard to biomechanics, application and dimensioning of compression osteosyntheses by external fixation is discussed in length.

Bone Nails↗
PubMed1993

[Oxygen carrying capacity of totally artificial red cell substitute--liposome embedded heme--in hemorrhagic beagle dogs].

Liposome embedded heme (L/H) was produced by embedding synthesized lipid-heme in liposomes. The oxygen carrying capacity of this totally artificial oxygen carrier was evaluated in dogs. Under controlled ventilation, 30ml/kg of blood was drawn. Thirty minutes after bleeding, 30mg/kg of the L/H solution was intravenously injected in group I (n = 6) and the same volume of normal saline solution was injected in group II (n = 7). No transfusion was performed in group III (n = 7). In group I, mixed venous O2 tension (PvO2), O2 transport (TO2) and O2 consumption (VO2) increased significantly compared with those observed before injection of the L/H (p < 0.05). PvO2 kept higher level compared with group II until 90 minutes after injection of the L/H (p < 0.05). Following the L/H injection, TO2 by the dogs' Hb was 187ml/min and that by the L/H was 43ml/min. VO2 from the dogs' Hb was 51ml/min and that from the L/H was 16ml/min. Thus TO2 by the L/H provided 19% of the total TO2 and VO2 from the L/H provided 24% of the total VO2. Thus, this exchange transfusion experiment show that the L/H has ability as an oxygen carrier to bind and to transport oxygen to the tissues.

Animals↗
PubMed1989

An investigation into the role of porcelain thickness in determining the load-carrying capacity of porcelain laminates.

The effect of specimen thickness on the strength of dental porcelain has been investigated. It has been shown that for core, dentine and combinations of these porcelains, the shell strength decreases with increasing thickness. Consequently, the load carrying capacity does not increase as much as might be expected with thicker sections. Possible reasons for this phenomenon and methods of limiting this effect are discussed.

Dental Porcelain↗
PubMed2000

[The influence on oxgen-carrying capacity of procine hemoglobin while attached PEG to increase its total molecular weight].

Increasing the total molecular weight of hemoglobin through PEG modification has been proved to be a better choice in prolonging vascular retention time. As a long, linear, hydrophilic molecular, PEG exerts significant influence on the oxygen-carrying properties of porcine hemoglobin (pHb) when attached. PEG-hemoglobins exhibit a wide range of differences in their properties depending on which molecular weight PEG is selected, how many PEGs are bound and whether the allosteric cofactors exist or not. Furthermore, DBBF intracross-linked pHbs are bound to various active PEG. As a result, with the combination of the three methods: DBBF intracross-linking, allosteric cofactors involving and PEG conjugating, a tetramer stable and high oxygen-carrying capacity pHb derivitive with large molecular weight is obtained.

Animals↗
PubMed1992

The role of oxygen-carrying capacity in myocardial ischemia.

Myocardial ischemia results when myocardial oxygen demand exceeds oxygen supply. The oxygen content of blood is only one of several interdependent variables influencing myocardial oxygen supply. The impetus for assessing the contribution of the oxygen content of blood to myocardial ischemia, and thus the need to treat anemia, stems from current concern about the risks associated with blood transfusion and the recognition that hemodilution has protean effects on the oxygen-carrying capacity of blood. The rheological changes that accompany hemodilution favorably influence the delivery of oxygen to the tissues and have the capacity to at least partially compensate for the decrease in blood oxygen content during hemodilution. However, nonrheological compensatory mechanisms (e.g., cardiac effects) also influence oxygen delivery and may profoundly influence the adequacy of tissue oxygenation. Furthermore, occlusive vascular lesions that restrict blood flow to the tissues also profoundly influence tissue oxygenation. The evidence in the myocardium and in systemic tissues indicates that considerable degrees of normovolemic hemodilution are well tolerated in physiological settings. In contrast, coexisting disease such as coronary artery stenosis may limit the patient population that benefits from normovolemic hemodilution. Unfortunately, well-controlled prospective studies of normovolemic hemodilution in patients with severe vascular or cardiac disease have not yet been conducted. As we progress to that point, it will be especially important to critically examine studies that use anesthetized or revascularized preparations. Results obtained under controlled conditions of hemodilution may not apply to postoperative anemia in awake patients with coronary artery disease who are experiencing the stress of surgery.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1981

[Oxygen tension in skeletal muscle in patients with reduced O2-carrying capacity (author's transl)].

In 10 patients (age: 31--72 years) oxygen supply of skeletal muscle was measured by pO2-multiwire technique. All patients suffered from chronic renal failure of differing etiologies and from chronic renal anemia. In muscle tissue 1,128 different O2-tensions were registered and the results were expressed as pO2-histograms. Seven of these pO2-histograms show a normal distribution, three are shifted to the left to lower O2-tensions. Therefore the microcirculation in the skeletal muscle of patients with chronic reduced O2-carrying capacity is largely undisturbed. The microcirculation is able to increase with exercise as shown by a shift to the right in the PO2-histogram. The use of the pO2-multiwire electrode is largely devoid of risk to the patient. Important pathological features may be demonstrated.

Carbon Dioxide↗
PubMed1982

The effect of changes in blood oxygen-carrying capacity on ventilation volume in the rainbow trout (Salmo gairdneri).

1. Changes in ventilation volume (Vg) of rainbow trout caused by hypercapnia, hypoxia and anaemia were measured directly by collection of expired water. 2. Exposure to hypercapnic water (PCO2 range 0.5-2 kPa) increased Vg (by up to four times) by augmenting ventilatory stroke volume; breathing frequency remained constant. O2 added to the inspired water in maintained hypercapnia reduced Vg at all but the highest level of PCO2. 3. Vg increased when blood oxygen content was decreased by exposure to normoxic hypercapnia, but addition of O2 to the water increased blood oxygen content and Vg decreased. 4. When blood oxygen-carrying capacity was depressed by hypoxia or anaemia, Vg increased as it did during normoxic hypercapnia. 5. We suggest that ventilatory responses to low levels of hypercapnia, to hyperoxic hypercapnia, to hypoxia, and to anaemia in trout are related to changes in levels of blood oxygen content under these conditions.

Anemia↗
PubMed1999

A follower load increases the load-carrying capacity of the lumbar spine in compression.

STUDY DESIGN: An experimental approach was used to test human cadaveric spine specimens. OBJECTIVE: To assess the response of the whole lumbar spine to a compressive follower load whose path approximates the tangent to the curve of the lumbar spine. SUMMARY OF BACKGROUND DATA: Compression on the lumbar spine is 1000 N for standing and walking and is higher during lifting. Ex vivo experiments show it buckles at 80-100 N. Differences between maximum ex vivo and in vivo loads have not been satisfactorily explained. METHODS: A new experimental technique was developed for applying a compressive follower load of physiologic magnitudes up to 1200 N. The experimental technique applied loads that minimized the internal shear forces and bending moments, made the resultant internal force compressive, and caused the load path to approximate the tangent to the curve of the lumbar spine. RESULTS: A compressive vertical load applied in the neutral lordotic and forward-flexed postures caused large changes in lumbar lordosis at small load magnitudes. The specimen approached its extension or flexion limits at a vertical load of 100 N. In sharp contrast, the lumbar spine supported a load of up to 1200 N without damage or instability when the load path was tangent to the spinal curve. CONCLUSIONS: Until this study, an experimental technique for applying compressive loads of in vivo magnitudes to the whole lumbar spine was unavailable. The load-carrying capacity of the lumbar spine sharply increased under a compressive follower load, as long as the load path remained within a small range around the centers of rotation of the lumbar segments. The follower load path provides an explanation of how the whole lumbar spine can be lordotic and yet resist large compressive loads. This study may have implications for determining the role of trunk muscles in stabilizing the lumbar spine.

Adult↗
PubMed1998

Acute hypercapnia increases the oxygen-carrying capacity of the blood in ventilated dogs.

OBJECTIVE: To test the hypothesis that PaCO2 levels generated during permissive hypercapnia may enhance arterial oxygenation, when ventilation is maintained. DESIGN: Prospective study. SETTING: Research laboratory in a hospital. SUBJECTS: One group of eight mongrel dogs (four male; four female). INTERVENTIONS: The dogs were anesthetized (30 mg/kg iv pentobarbital), intubated, and cannulated in one femoral artery and vein. While paralyzed with 0.1 mg/kg/hr iv vecouronium bromide, all subjects were ventilated with room air. Anesthesia was maintained, using 2 to 3 mg/kg/hr iv pentobarbital. Arterial hypercapnia at the levels generated during permissive hypercapnia was produced by stepwise increases in the dry, inspired Pco2 (PiCO2) (0, 30, 45, 60 and 75 torr [0, 4, 6, 8, and 10 kPa]; 15 mins each). MEASUREMENTS AND MAIN RESULTS: Blood gas profiles were determined at each level of hypercapnia. The minute volume was maintained at the baseline level during all exposures. Arterial hypercapnia produced gradual and significant increases in the hemoglobin concentration. These increases were approximately 6%, 7%, 11%, and 14% at PiCO2 of 30, 45, 60, and 75 torr (4, 6, 8, and 10 kPa), respectively (p < .05; repeated analysis of variance followed by Dunnett multiple comparisons test). In parallel, the oxygen content increased by approximately 6%, 7%, 11%, and 13%, respectively. During hypercapnic trials, the PaO2 remained at the normal range, whereas the dry, inspired PO2 (PiO2) was reduced from 150 to 138 torr (20 to 18.4 kPa). The average PaO2 at the highest investigated level of arterial hypercapnia was at a normal range. The hemoglobin concentration and oxygen content returned to baseline values 30 mins after hypercapnic trials. The PaCO2 and pH became normalized 15 mins after hypercapnic trials. Indirect evidence for a similar response to hypercapnia in humans is presented. CONCLUSIONS: Permissive hypercapnia due to inhaled CO2 increases oxygen-carrying capacity in dogs. The PaO2 remains at normal range even at a PiCO2 of 75 torr (10 kPa). The benefits of these effects during permissive hypercapnia, due to controlled hypoventilation, warrants investigation.

Acute Disease↗
PubMed2003

Glove powder's carrying capacity for latex protein: analysis using the ASTM ELISA test.

Glove donning powders carry latex proteins and disperse them into the workplace environment. We have used the ASTM D6499 ELISA to quantify the amount of latex antigen bound to and carried by glove powders. We could differentiate between a small amount of protein actually bound to the powders and a larger amount carried by the powder. Enhanced binding of a major allergen, Hev b 5, to the starch powders was demonstrated by Western blot. The D6499 ELISA is able to measure total latex antigen, soluble and powder bound, simultaneously without the need to centrifuge the samples.

Enzyme-Linked Immunosorbent Assay↗