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PubMedDate not supplied

The AaDO2 and venous admixture at varying inspired oxygen concentrations in chronic obstructive pulmonary disease.

The alveolar to arterial oxygen pressure difference (AaDO2) and pulmonary venous admixture (Qs/Qt) were measured in 32 patients with chronic obstructive pulmonary disease during right heart catheterization at inspired oxygen concentrations (FIO2) of 21, 24, 28, 35, and 40%. Patients without chronic hypercapnia (PaCO2 is less than 45 torr, group A) had Qs/Qt less than 25% while breathing room air; their AaDO2 rose at a rate of 3 torr for each percent increase in FIO2. In those with chronic hypercapnia (PaCO2 greater than 44 torr., (group B), THE Qs/Qt was always greater than 24% during air breathing and the AaDO2 rose at a rate of 5 torr for each percentage increase in FIO2. These changes should be considered in the interpretation of the AaDO2 in patients with COPD in whom the FIO2 is changed during the course of therapy. The Qs/Qt fell curvilinearly with increasing FIO2 but the rates of fall were quantitatively different in groups A and B. A physiological explanation for the changes in Qs/Qt and ADO2 which result from changes in FIO2 is presented.

Arteries↗
PubMed1989

Prediction of arterial oxygen partial pressure from intrapulmonary venous admixture.

A short program was developed to predict the PaO2 at a given FIO2 by using arterial and mixed venous blood gas data obtained at an FIO2 of 1.0. Our program resolves Adair's equation and the shunt equation inversely, on the assumption that intrapulmonary venous admixture and the arteriovenous oxygen content difference remain constant during the study. The study was conducted on 19 patients with respiratory failure who were intubated and mechanically ventilated. According to linear regression analysis, regression coefficients of 0.91 and 0.97 were obtained between the measured PaO2 values and those estimated by the arterial/alveolar oxygen tension ratio (PaO2/PaO2) and our program, respectively (n = 23). The PaO2 values were predicted more accurately by our program than those calculated by PaO2/PaO2. Because our program is simple enough to be carried out with a pocket computer, it may be helpful in a bedside decision of lowering FIO2, especially in patients who require a high FIO2 level to maintain sufficient arterial oxygenation.

Blood Gas Analysis↗
PubMed1990

Reduced venous admixture in hemorrhagic hypovolemia: maintenance of arterial oxygenation by selective pulmonary vascular collapse.

In nine anesthetized and ventilated swine, a microcomputer calculated cardiac output, venous admixture (Qsp/Qt) and physiologic deadspace (VD/VT) every 20 sec, utilizing dual oximetry and a gas exchange analyzer. After lung injury with ethchlorvynol (ECV), animals were bled 40% blood volume over 40 min. Mean cardiac output decreased 7.0 to 2.2 L/min (p less than .05) accompanied by a decrease in mean Qsp/Qt from 0.28 to 0.14 (p less than .05) and an increase in mean VD/VT from 0.39 to 0.54 (p less than .05). Arterial Hgb saturation (Sao2) increased from 88 +/- 7% to 90 +/- 6%. On regression of all data points for each variable, Qsp/Qt had a positive correlation with cardiac output (r = .90), mean arterial pressure (MAP, r = .87), mean pulmonary artery pressure (MPAP, r = .86), and mixed venous Hgb saturation (Svo2, r = .89, p less than .001). VD/VT had an inverse correlation with cardiac output (r = -.90), MAP (r = -.82), Qsp/Qt (r = -.83), MPAP (r = -.77), and Svo2 (r = -.92, p less than .001). The decreasing Qsp/Qt and increasing VD/VT, with decreasing pulmonary perfusion pressures, were attributed to selective loss of perfusion to alveoli with low ventilation/perfusion ratios.

Animals↗
PubMed1990

Continuous, in vivo pulmonary venous admixture from fiberoptically measured hemoglobin saturations.

In six anesthetized swine, pulmonary venous admixture (Qsp/Qt) was calculated by four methods: a) Qsp/Qt 1, fiberoptically measured arterial and mixed venous Hgb saturation (SaO2 and SvO2), PaO2 and PvO2 derived from saturations; b) Qsp/Qt 2, fiberoptically measured SaO2 and SvO2, PaO2 and PvO2 measured by blood gas analysis; c) Qsp/Qt 3, PaO2 and PvO2 measured by blood gas analysis, SaO2 and SvO2 derived from tensions; d) Qsp/Qt 4, SaO2 and SvO2 measured by bench oximetry, PaO2 and PvO2 derived from saturations. Input from the fiberoptic catheters was fed into a computer programmed to calculate Qsp/Qt 1 every 20 sec. Fifty-eight of these values were compared with simultaneously calculated Qsp/Qt 2, 3, and 4. There was no difference between fiberoptic and derived SaO2 or fiberoptic and cooximetric SvO2. Correlations and slopes for Qsp/Qt 1 with Qsp/Qt 2, 3, and 4 were significant (p less than .05). Comparing mean differences, Qsp/Qt 1 was significantly different only from Qsp/Qt 3 (p less than .01). We conclude that dual oximetry reliably tracks Qsp/Qt.

Animals↗
PubMed1997

Bound iron admixture prevents the spontaneous generation of peroxides in total parenteral nutrition solutions.

BACKGROUND: Parenteral administration of iron is a matter of controversy because it is feared that it could contribute to oxidative reactions. The aim of this study was to verify if irondextran participates in the redox reactions occurring in total parenteral nutrition (TPN) solutions. METHODS: Irondextran was compared with different forms of iron in the interaction with peroxides. Hydroperoxide levels were measured by a colorimetric technique in TPN solutions, in presence of varying sources (FeCl2, FeSO4, irondextran, iron sorbitol) and concentrations (0-0.8 mM) of iron. The consumption and inhibition of peroxide generation were tested by analyzing the effect of iron on different sources of peroxides (H2O2, tert-butyl and cumen hydroperoxide). The free radicals produced under conditions of a Fenton-like reaction were measured by the oxidation of scopoletin. And the proportion of Fe3+ freed by both bound-iron sources was counted by measuring the masking effect on the thiol function of cysteine. RESULTS: Free-iron admixture to parenteral nutrition induces the formation of free radicals, whereas sources of bound-iron inhibit the generation of peroxides in parenteral nutrition without implying a Fenton-like reaction. CONCLUSION: For patients requiring iron supplementation, bound-iron should be added during the preparation of TPN solutions, because it protects against the spontaneous generation of peroxides.

Colorimetry↗
PubMed2004

Putative ancestral origins of chromosomal segments in individual african americans: implications for admixture mapping.

Theoretically, markers that distinguish European from West African ancestry can be used to examine the origin of chromosomal segments in individual African Americans. In this study, putative ancestral origin was examined by using haplotypes estimated from genotyping 268 African Americans for 29 ancestry informative markers spaced over a 60-cM segment of chromosome 5. Analyses using a Bayesian algorithm (STRUCTURE) provided evidence that blocks of individual chromosomes derive from one or the other parental population. In addition, modeling studies were performed by using hidden real marker data to simulate patient and control populations under different genotypic risk ratios. Ancestry analysis showed significant results for a genotypic risk ratio of 2.5 in the African American population for modeled susceptibility genes derived from either putative parental population. These studies suggest that admixture mapping in the African American population can provide a powerful approach to defining genetic factors for some disease phenotypes.

Black or African American↗
PubMed2004

Roughening of the interfaces in (1+1) -dimensional two-component surface growth with an admixture of random deposition.

We simulate competitive two-component growth on a one-dimensional substrate of L sites. One component is a Poisson-type deposition that generates Kardar-Parisi-Zhang (KPZ) correlations. The other is random deposition (RD). We derive the universal scaling function of the interface width for this model and show that the RD admixture acts as a dilatation mechanism to the fundamental time and height scales, but leaves the KPZ correlations intact. This observation is generalized to other growth models. It is shown that the flat-substrate initial condition is responsible for the existence of an early nonscaling phase in the interface evolution. The length of this initial phase is a nonuniversal parameter, but its presence is universal. We introduce a method to measure the length of this initial nonscaling phase. In application to parallel and distributed computations, the important consequence of the derived scaling is the existence of the upper bound for the desynchronization in a conservative update algorithm for parallel discrete-event simulations. It is shown that such algorithms are generally scalable in a ring communication topology.

Journal Article↗
PubMed2005

Admixtures to d-wave gap symmetry in untwinned YBa2Cu3O7 superconducting films measured by angle-resolved electron tunneling.

We report on an ab anisotropy of Jc parallel b/Jc parallel a approximately/= 1.8 IcRn parallelb/IcRn parallel a approximately/= 1.2 and in ramp-edge junctions between untwinned YBa2Cu3O7 and s-wave Nb. For these junctions, the angle theta with the YBa2Cu3O7 crystal b axis is varied as a single parameter. The RnA(theta) dependence presents twofold symmetry. The minima in IcRn at theta approximately/= 50 degrees suggest a real s-wave subdominant component and negligible d(xy)-wave or imaginary s-wave admixtures. The IcRn(theta) dependence is well fitted by 83% dx2-y2-, 15% isotropic s-, and 2% anisotropic s-wave order parameter symmetry, consistent with deltab/deltaa approximately/= 1.5.

Journal Article↗
PubMed2002

Admixture analysis of smooth pursuit eye movements in probands with schizophrenia and their relatives suggests gain and leading saccades are potential endophenotypes.

Abnormalities during a smooth pursuit eye movement task (SPEM) are common in schizophrenic patients and their relatives. This study assessed various components of SPEM performance in first-degree unaffected relatives of schizophrenic patients. One hundred individuals with schizophrenia, 137 unaffected first-degree relatives, and 69 normal controls completed a 16.7 degrees/s SPEM task. Smooth pursuit gain, catch-up saccades (CUS), large anticipatory saccades, and leading saccades (LS) were identified. Groups were compared with parametric and admixture analyses. Schizophrenic patients performed more poorly than unaffected relatives and normals on gain, CUS, and LS. Unaffected relatives were more frequently impaired than normals only on gain and LS. Relatives of childhood-onset and adult-onset probands had similar impairments. Gain and frequency of leading saccades may be genetic endophenotypes in childhood-onset and adult-onset schizophrenia.

Adolescent↗
PubMed1994

Patient-controlled epidural analgesia with sufentanil following caesarean section: the effect of adrenaline and clonidine admixture.

Sixty patients, scheduled for Caesarean section were randomly allocated to receive by the epidural route in a double-blind fashion one of the following patient-controlled analgesia mixtures for the relief of postoperative pain: sufentanil 2 micrograms.ml-1 in 0.9% sodium chloride, sufentanil 2 micrograms.ml-1 + adrenaline 2.5 micrograms.ml-1, or sufentanil 2 micrograms.ml-1 + clonidine 3 micrograms.ml-1. Patient-controlled analgesia settings were a basal infusion rate of 2.5 ml.h-1, an incremental dose of 2.5 ml, a lockout interval of 10 min and a 1-h limit of 10 ml. Whereas patient demographics and pain scores between the groups were not different, the 24-h consumption of sufentanil was significantly lower in the groups receiving a combination (167.5 SD 45 and 139.1 SD 31.9 micrograms for the adrenaline and clonidine groups respectively) as compared to the plain sufentanil regimen (208.2 SD 38.9 micrograms). Although sufentanil requirements were the lowest in the clonidine admixture group, there were no differences with regard to sedation as compared to the plain sufentanil group. The quality of sleep appeared to be significantly better in the sufentanil/adrenaline group despite a significantly lower degree of sedation and higher incidence of pruritus. Treatment of pruritus with naloxone did not seem to influence the quality of analgesia.

Adult↗
PubMed1975

Changes of EEG and pulmonary venous admixture during a protein load in patients with cirrhosis.

21 patients with cirrhosis of the liver and 24 control patients were studied before and after a protein load (120 g protein per day during one week). An EEG was recorded and a visual assessment of frequency pattern was performed. Venous admixture was estimated during hyperoxia. According to the EEG frequency pattern the patient group with cirrhosis was subdivided into those with EEG slowing after the protein load (n = 7) and those without (n = 14). The following results were obtained: 1) Resting arterial blood gases did not change in either group. 2) There was a significant increase of the AaD02 (difference between alveolar p02 and peripheral arterial p02) in cirrhotics and controls. 3) The increase in AaD02 was significantly larger in those cirrhotics showing EEG slowing compared to those without EEG - slowing or to the controls. 4) Fractional venous admisture increased significantly in those cirrhotics showing EEG slowing. There was no significant change in those patients who did not show EEG changes or in the controls.

Blood Pressure↗
PubMed1984

Stability of cefsulodin in aqueous buffered solutions and some intravenous admixtures.

The stability of cefsulodin in aqueous solutions of various pH values, buffer concentrations, ionic strengths and intravenous admixtures were studied using a stability-indicating high-pressure liquid chromatography method. The pH range of optimum stability was determined to be 3.2-5.7. Cefsulodin was more stable on the acidic and less on the alkaline side as compared with most of the other cephalosporins such as cefoxitin (pH range of optimum stability approximately 4-7). In 5% dextrose and 0.9% sodium chloride injection, cefsulodin was stable (at least 90% potent) for about 1, 17 and at least 60 days at 24 degrees, 5 degrees and -10 degrees C, respectively.

Buffers↗
PubMed1989

Kinetics of bacterial growth in simple intravenous solutions and admixtures.

The growth of bacteria in intravenous solutions and admixtures has been studied under stationary conditions of incubation. All the solutions were inoculated with 100 organisms/ml, incubated at room temperature (27 degrees C) or (37 degrees C), with samples withdrawn at specified time intervals, and plated in quadruplicates. The simple intravenous (i.v.) solutions did not support significant growth (P greater than 0.05) of any of the micro-organisms. Growth in i.v. solutions containing 1% blood was very significant (P greater than 0.05), as demonstrated by the high apparent growth rate constants (K). The ratio of K for beta-lactamase producing bacteria (beta-lac+) over that for non-beta-lactamase producing bacteria (beta-lac-) was significant (P less than 0.05) at 37 degrees C compared to that at 27 degrees C. The higher K values for B. cereus in benzylpenicillin and cefuroxime solutions, respectively, compared to those in antibiotic-free solutions, may be attributable to hydrolysis of the drugs, while the low K values for B. subtilis in the same solutions may be attributed to the inhibitory effects of the drugs. In conclusion, minute quantities of blood in i.v. solution tend to cause bacteria to multiply rapidly. The presence of beta-lactamase producing species might, in addition, hydrolyse susceptible beta-lactam antibiotics which are common additives to i.v. fluids.

Bacillus↗
PubMed1990

Chemical stabilities of cefuroxime sodium and metronidazole in an admixture for intravenous infusion.

The chemical stabilities of cefuroxime sodium and metronidazole, when mixed together for intravenous infusion, were studied by high-performance liquid chromatography (HPLC). The critical factor in the stability of the admixture was the degradation of cefuroxime sodium. At 25 degrees C, cefuroxime degraded by first-order kinetics with a rate constant of 7.04 x 10(-2)/day and a t90 (time to reach 90% of the original concentration) of 36 h. At 4 degrees C the rate constant was 5.23 x 10(-3)/day with a t90 of 20 days, however, over the time-scale studied, the kinetics approximated to zero-order at this temperature. The mixture was also stable with respect to metronidazole, nitrite ion and appearance. A 7-day storage life at 4 degrees C can be given to the mixture.

Cefuroxime↗
PubMed2005

Allopatric origins of sympatric brook charr populations: colonization history and admixture.

Natural selection is presumed to be the driving force behind the occurrence of phenotypically and genetically divergent populations in sympatry within many north temperate freshwater fishes. If, however, these populations have different ancestral origins, history could also contribute to their divergence. We previously found evidence for the role of selection in the evolution of divergent outflow and inflow breeding populations of migratory brook charr (Salvelinus fontinalis) inhabiting postglacial Mistassini Lake (Quebec, Canada). Here, we show that these populations do not have a common origin, through the use of admixture and spatial analyses with seven microsatellite loci. Divergent populations clustered into two different population groups when compared to samples from surrounding drainages, although inflow populations appeared to be more admixed between the two population groups than the outflow population. These results are noteworthy since outflow and inflow populations were monomorphic at mitochondrial DNA (338-bp sequence of the control region) and are only moderately differentiated (mean F(ST) = 0.10). Colonization by two ancestral populations was also consistent with known outflow direction changes throughout lake formation. In addition to providing insight into how phenotypic divergence in sympatry may have been affected by the nature (i.e. timing and direction) of colonization of ancestral populations, our results also suggest that ancestral populations may have differed in their ability to colonize certain lake habitats.

Animals↗
PubMed2007

High intercontinental migration rates and population admixture in the sapstain fungus Ophiostoma ips.

Ophiostoma ips is a common fungal associate of various conifer-infesting bark beetles in their native ranges and has been introduced into non-native pine plantations in the Southern Hemisphere. In this study, we used 10 microsatellite markers to investigate the population biology of O. ips in native (Cuba, France, Morocco and USA) and non-native (Australia, Chile and South Africa) areas to characterize host specificity, reproductive behaviour, and the potential origin as well as patterns of spread of the fungus and its insect vectors. The markers resolved a total of 41 alleles and 75 haplotypes. Higher genetic diversity was found in the native populations than in the introduced populations. Based on the origin of the insect vectors, the populations of O. ips in Australia would be expected to reflect a North American origin, and those in Chile and South Africa to reflect a European origin. However, most alleles observed in the native European population were also found in the native North American population; only the allele frequencies among the populations varied. This admixture made it impossible to confirm the origin of the introduced Southern Hemisphere (SH) populations of O. ips. There was also no evidence for specificity of the fungus to particular bark beetle vectors or hosts. Although O. ips is thought to be mainly self-fertilizing, evidence for recombination was found in the four native populations surveyed. The higher genetic diversity in the North American than in the European population suggests that North America could be the possible source region of O. ips.

Alleles↗