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Biomedical subjects

J E Moore

Publications and source records attributed to J E Moore.

At least 181 records · Page 10Linked to original sources
PubMed1994

Pulsatile velocity measurements in a model of the human abdominal aorta under resting conditions.

Oscillations in near-wall velocity direction have been found to correlate with atherosclerotic plaque localization in the carotid sinus bifurcation. However, it remains unproven whether these conditions could account for the localization of the disease at other sites where atherosclerosis forms. The abdominal aorta is an important site of clinical disease in a relatively straight segment of artery. This study was initiated to quantify the velocity field in the abdominal aorta in order to determine if local differences in hemodynamic velocity directions could account for the localization of disease in this segment. Magnetic Resonance Imaging velocimetry was used to measure the pulsatile velocity profiles in an anatomically accurate in vitro model of the abdominal aorta. Velocities measured in the suprarenal aorta were laminar and reversed minimally, comparing well with theoretical solutions of Womersley flow (r = 0.96). The time-averaged velocity was +3.0 cm/s near-wall at a distance of 1 mm away from the wall. In the infrarenal aorta, the maximal velocities were skewed toward the anterior wall. At the posterior wall, velocity oscillated in direction and was retrograde for 82 percent of the cardiac cycle. The time-averaged velocity near the posterior wall was -12.5 cm/s as compared to +3.00 cm/s near the anterior wall. At the aortic bifurcation, the locations of maximal and minimal velocities in this slice were concentrated near the lateral posterior walls. This study quantifies the magnitude of low and oscillatory velocity that may exist in the abdominal aorta and suggests that there is a strong relationship between the velocities in the retrograde direction under resting conditions and the distribution of atherosclerotic plaque.

Aorta, Abdominal↗
PubMed1994

Hemodynamics in the abdominal aorta: a comparison of in vitro and in vivo measurements.

In vivo measurements of blood velocity profiles are difficult to obtain and interpret, since the parameters that govern the normally highly complex flow situation may not be fully quantified or understood at the time of measurement. In vitro flow models have been used often to better understand vascular hemodynamics. The assumptions made in the design of these models limit the applicability of the results. In this study, in vitro flow measurements made in a carefully designed model of the abdominal aorta were compared with in vivo measurements obtained with magnetic resonance imaging. In the suprarenal aorta, the velocity profiles were mostly forward and axisymmetric in both the in vitro and in vivo cases. In the infrarenal aorta, there was extensive flow reversal noted near the posterior wall in both cases. In the aortic bifurcation, two peaks of flow reversal were noted near the lateral posterior walls, and M-shaped velocity profiles were observed in late diastole. The in vitro and in vivo measurements exhibited good qualitative agreement. The in vitro model was accurate in modeling the in vivo hemodynamics of the abdominal aorta. The complex phenomena observed in vivo were explained on the basis of knowledge gained from the in vitro study.

Adult↗
PubMed1993

Calcium accumulation by organelles within Myxicola axoplasm.

1. 45Ca2+ accumulation into inulin-inaccessible compartments within cytoplasm from the giant axon of Myxicola infundibulum was measured as a function of free calcium, pH, and time. Accumulation reached a maximum after 1 h and remained stable for at least 3 h. 2. At 0.5, 5, and 50 microM [Ca2+], in the presence of 1 mM ATP or 5 mM succinate, steady-state calcium uptake had a bell-shaped dependence on pH with a maximum near pH 7. Uptake was abolished by the proton uncoupling reagent carbonyl cyanide p-trifluoromethoxy-phenylhydrazone (FCCP, 4 micrograms ml-1). 3. Uptake of the membrane permeant cation, [14C]-tetraphenylphosphonium (TPP+), also had a bell-shaped dependence on pH with a maximum pH approximately 7, suggesting a pH dependence of the electrical potential of a membrane enclosed cytoplasmic compartment. Cyanide (2 mM) inhibited TPP+ uptake. 4. Inositol 1,4,5-trisphosphate (IP3, 10 microM), reduced steady-state calcium accumulation by 20-22% at 0.5 microM free calcium, pH 7 (P < 0.01, n = 16) and at 5 microM free calcium, pH 8 (P < 0.0005, n = 35). No effects of IP3 were found at other pH or calcium concentrations. 5. Neither guanosine 5'-triphosphate (GTP) nor inositol 1,3,4,5-tetrakisphosphate (IP4) had an effect on calcium uptake (5 microM [Ca2+], pH 8). 6. At 0.5 microM free calcium; vanadate (10 microM) inhibited 20-30%, of the 45Ca2+ accumulation, thapsigargin (33 nM) inhibited 20-30%, and cyanide (2 mM) plus oligomycin B (2 micrograms ml-1), or valinomycin (1 microM), inhibited 70-80%. The fraction of uptake sensitive to thapsigargin fell as the free calcium increased; however, the sensitivity of uptake to cyanide plus oligomycin B was approximately 80% for 0.5, 5.0, and 50 microM [Ca2+]. 7. Thapsigargin had no additional inhibiting effect in the presence of cyanide plus oligomycin B. IP3 had no effect in the presence of cyanide plus oligomycin B or other mitochondrial inhibitors. 8. Results suggest the presence of both mitochondrial (70-80%) and non-mitochondrial (20-30%) calcium pools in this system (at 0.5-5.0 microM Ca2+). The apparent non-mitochondrial uptake (sensitive to thapsigargin, or IP3) is not detectable in the presence of mitochondrial inhibitors. We interpret these results as evidence of functional communication between mitochondrial and non-mitochondrial calcium stores.

Animals↗
PubMed1993

Determinants of forage quality in Pensacola bahiagrass and Mott elephantgrass.

Our objective was to determine animal responses and forage characteristics that could explain the greater forage quality of 'Mott' dwarf elephantgrass (Pennisetum purpureum Schum.) than that of 'Pensacola' bahiagrass (Paspalum notatum Flugge). Both grasses were harvested after 5 wk of regrowth in June and September. Sheep fed Mott hays had greater (P = .001) voluntary intake of digestible OM (DOM) than did those fed Pensacola, but voluntary intake of ash-free NDF (NDFa) did not differ (P = .21) between grasses. When hays were fed at equal NDFa intakes, sheep fed Mott chewed at a greater (P = .002) rate during eating, spent less (P = .028) time ruminating per unit OM intake, and had smaller (P = .006) prefeeding digesta pools of total and indigestible NDFa. Mott hays had greater N and K and smaller NDFa concentrations. Mott had greater (P = .001) epidermis and smaller (P = .001) sclerenchyma proportions in leaf blades, and leaf epidermis of Mott was more digestible (P = .011) in vitro. For both grasses, hays harvested in June had greater (P = .011) voluntary intake of DOM and shorter (P = .082) mean retention time of small ruminal digesta particles (< 1.18 mm) than did those harvested in September. Within grasses, there were no seasonal differences in NDFa concentration in hay, or in leaf anatomy. A less fibrous leaf structure and a more readily digested leaf epidermis may have accounted for the greater DOM intake of Mott than of Pensacola, but the greater DOM intake of hays harvested in June than of those harvested in September was not explained by measured forage characteristics.

Animal Feed↗
PubMed1992

Open heart surgery: intensive care component, clinical profile and costs over one year.

A profile of 333 patients admitted to the intensive therapy unit, Waikato Hospital, over one year ending 30 June 1990, is presented. A close costing of a representative sample of 30 of those patients was done. The average cost of their intensive care stay was $2948 per patient. Twenty-four of the patients cost an average $2200 and the other six cost an average $5700.

Adolescent↗
PubMed1992

Pulsatile flow visualization in the abdominal aorta under differing physiologic conditions: implications for increased susceptibility to atherosclerosis.

The infrarenal abdominal aorta is a common site for clinically significant atherosclerosis. As has been shown in other susceptible locations, vessel geometry, flow division rates, and pulsatility may result in hemodynamic conditions which influence the preferential localization of disease in the abdominal aorta segment. Pulsatile flow visualization was performed in a glass model of the aorta constructed from measurements of angiograms and cadaver aortas. Flow rates and pulsatile waveforms were varied to reflect typical physiological conditions. Under normal resting conditions, the flow patterns in the infrarenal aorta were more complex than those in the suprarenal location. Time varying vortex patterns appeared at the level of the renal arteries and propagated through the infrarenal aorta into the common iliac arteries. A region of oscillating velocity direction extended from the renal arteries to the aortic bifurcation along the posterior wall. Dye became trapped along the posterior wall, requiring several cardiac cycles for clearance. In contrast, there was rapid clearance of the dye in the anterior aorta. Under postprandial conditions, the flow patterns in the aorta were basically unchanged. Simulated exercise conditions created laminar hemodynamic features very different from the resting conditions, including a decrease in dye residence time. This study reveals significant time-dependent variations in the hemodynamics of the abdominal aorta under differing physiologic conditions. Hemodynamic factors such as low wall shear stress, oscillating shear direction, and high particle residence time may be related to the clinically seen preferential plaque localization in the infrarenal aorta.

Angiography↗
PubMed1991

Fluid and particulate retention times in sheep as influenced by intake level and forage morphological composition.

Objectives of this study were 1) to measure small-particle and liquid mean retention time (MRT) of 12 grass hays similar in NDF (61.3 +/- 1.9% NDF) but differing in morphological composition and to relate passage rates to proportions of blade, sheath and stem and 2) to evaluate the influence of MRT of small and large blade and stem fractions and large sheath fractions, in addition to morphological composition, on intake and digestibility of the 12 hays. In each of two periods, 24 sheep (wethers) were offered one of 12 hays at three consecutive levels of feeding: (L1) ad libitum, allowing 15% refusal; (L2) restricted to 100% of hay consumed ad libitum by an individual wether during L1; and (L3) 1.8% of BW on a DM basis. Hays offered included two sorghum-sudan, four barley, four oat and two pearl millet. Marked particles were pulse-dosed in L2 and L3. Large and small particles of stem and leaf were extracted with neutral detergent and marked with Cr or rare earth metals. Marked large and small stem particle MRT generally were longer (P less than .05) than those of corresponding large and small blade particles. Large sheath particles generally had an intermediate (P less than .05) MRT between those of large stem and blade particles. Mean retention times of marked fractions were lower (P less than .05) in L2 than in L3. Small particle MRT in L2 was longer than MRT for liquid, though correlations were high (r = .74 to .86, P less than .01). Large particles were retained longer than small particles. Particle size, morphology, and percentage of stem in the forage influenced the mean retention time. Use of representative samples of all fractions fed to measure retention times may lead to a better understanding of ruminal function and to improvements in explanations of intake regulation, because marked fractions do not behave identically for all forages.

Animal Feed↗
PubMed1990

Intake and digestibility by wethers as influenced by forage morphology at three levels of forage offering.

Animals on pasture do not always have the opportunity for ad libitum consumption. Our objectives were to determine effects of intake level on digestibility of 12 grass hays, and to relate differences in intake and digestibility to proportions of leaf blade, leaf sheath and stem. In each of two periods, 24 wethers were offered one of 12 hays at three consecutive levels of feeding: (L1) ad libitum, allowing 15% refusal; (L2) restricted to 100% of hay consumed ad libitum by individual wether during L1; and (L3) 1.8% of BW on a DM basis. Hays offered included two sorghum-sudan, four barley, four oat and two pearl millet. Hays were similar in NDF concentration but differed in morphological composition Organic matter intake averaged 1.99 +/- .04, 1.79 +/- .04 and 1.52 +/- .01% of BW for L1, L2 and L3, respectively. Organic matter digestibilities averaged 71.8 +/- .55 72.4 +/- .60 and 72.3 +/- .65% for L1, L2 and L3, respectively. Intake SEM within hays were lower with restricted intakes (L3), whereas the opposite was observed for the SEM for digestibility. Forage morphological composition within feeding level influenced intake and digestibility by altering diet selection capabilities of wethers. Wethers did not consume equal NDF amounts, ranging form .95 to 1.47% of BW, because hays differed in morphological composition. Ash-free ADF and 72% sulfuric acid lignin were higher (P less than .01) in stem than in blade or sheath. In vivo digestibilities measured under restricted feeding conditions were related more closely (P less than .05) to in vitro estimates of digestibility than were digestibilities measured under ad libitum conditions (r = .72, .79 and .85 for L1, L2 and L3, respectively). This study demonstrates that variation in morphological characteristics of forages may account for part of the difference in voluntary intake of forages of similar chemical composition. New knowledge in this area will be valuable in developing improved forage quality prediction procedures.

Animal Feed↗
PubMed1989

Flow patterns in the abdominal aorta under simulated postprandial and exercise conditions: an experimental study.

Specific hemodynamic factors have been shown to be associated with atherosclerotic plaque localization at the human carotid bifurcation. Flow field characteristics may also determine plaque distribution in the abdominal aorta. We therefore characterized flow patterns in a glass model abdominal aorta that included its major branches under conditions of steady flow. Outflow resistances of the celiac, superior mesenteric, renal, inferior mesenteric, and iliac arteries were varied to produce flow distributions consistent with rest, the postprandial state, and vigorous lower limb exercise. Flow patterns were visualized with three colors of dye injected simultaneously through capillary tubes at selected locations and recorded as still photographs and by cinephotography on videotapes. Under resting conditions a large region of flow separation and stagnation occurred at the posterior wall of the aorta directly opposite the orifices of the superior and inferior mesenteric arteries. Similar separation regions were observed during the simulated postprandial state but diminished markedly when distal outflow was increased to levels consistent with exercise. In the highly susceptible infrarenal aortic segment, beginning about 2 cm below the renal artery orifices, multiple secondary flow patterns with three to four counterrotating vortex formations were observed under both resting and postprandial conditions but disappeared in the exercise state. Secondary flow patterns were not noted in the suprarenal abdominal aorta, which is usually relatively spared. Such features have been related to plaque localization elsewhere, and the disappearance of these patterns with increased flow velocity during exercise is consistent with the previously noted protective effect of unidirectional laminar high-flow states. The beneficial effects of physical fitness programs may be related in part to these hemodynamic modifications.

Aorta, Abdominal↗
PubMed1989

Dietary interaction of cane molasses with source of roughage: intake and lactation effects.

Effects of cane molasses at 0, 4, and 8% of DM in complete mixed diets were evaluated when molasses was fed to lactating dairy cows with cottonseed hulls, alfalfa haylage, or both combined. Thirty-six mature Holstein cows from mid to late lactation were used in a partially balanced incomplete block design with three 28-d periods. Variables measured were DM intake, milk yield, and composition. With cottonseed hull diets (30% of DM), molasses improved milk yield, milk fat percentage, solids-corrected milk, and feed efficiency. Dry matter intake was not affected by molasses. With alfalfa haylage diets (35% of DM), 8% molasses depressed actual milk yield and solids-corrected milk, DM intake, milk fat percentage, milk protein percentage, and feed efficiency. Milk fat percentage was increased with 4% molasses. With 65% alfalfa haylage diets, most variables measured were unaffected by molasses; however, with 8% molasses, DM intake increased and milk protein percentage decreased. In diets with both roughages combined, molasses did not affect any variable measured; however, these diets gave highest solids-corrected milk yields. Results show clearly that molasses effects depend on percentage molasses and type and amount of roughage in the diet.

Animal Feed↗
PubMed1988

Differences between psychotic and nonpsychotic patients on content dimensions of the MMPI Sc scale.

This study examined elevated MMPI Sc scores among psychotic and nonpsychotic patients to determine whether homogeneous item-content dimensions could clarify the precise meaning of elevations on scale Sc. A total of 45 psychotic patients were compared with 56 nonpsychotic psychiatric patients on the Harris and Lingoes subscales of the Sc scale. All subjects had T-score elevations on scale Sc greater than or equal to 70. The two criterion groups did not differ on overall scale Sc scores, but a distinctive pattern of subscale scores emerged that discriminated the samples. Psychotic patients obtained significantly higher scores on subscales measuring bizarre thinking and perceived loss of control over impulses and emotions. Conversely, nonpsychotics endorsed significantly more items on subscales concerned with symptoms of depression, anxiety, and thinking difficulties. These data suggest that homogeneous item-content dimensions of the Sc scale provide a means for distinguishing between psychotic and nonpsychotic patients who otherwise appear similar on overall scale Sc.

Adult↗
PubMed1987

Lay person use of automatic external defibrillation.

The ability of lay persons to learn and retain defibrillation skills using an automatic external defibrillator (AED) was assessed. Thirty-four family members of cardiac arrest survivors were trained in CPR techniques and defibrillation, and evaluated for performance of skills immediately following training and at six-week and three-month follow-ups. All but two were successfully trained to complete three cycles of CPR interspersed with three defibrillatory shocks in an average of four minutes with the first shock delivered in an average of two minutes. Although there were decrements in the speed and quality of performance at each follow-up period (P less than .01), we conclude that most lay persons can learn to operate an AED safely and under simulated conditions provide defibrillatory shocks an average of eight minutes faster than typical response times of emergency medical technicians. These results suggest that AEDs can be placed in many homes of patients at high risk for cardiac arrest.

Adult↗
PubMed1986

Empirically derived pain-patient MMPI subgroups: prediction of treatment outcome.

Fifty-seven male chronic pain patients admitted to an inpatient multimodal pain treatment program at a Midwestern Veterans Administration hospital completed the MMPI, Profile of Mood States (POMS), Tennessee Self-Concept Scale (TSCS), Rathus Assertiveness Schedule (RAS), activity diaries, and an extensive pain questionnaire. All patients were assessed both before and after treatment, and most also were assessed 2-5 months prior to treatment. No significant changes occurred during the baseline period, but significant improvements were evident at posttreatment on most variables: MMPI, POMS, TSCS, RAS, pain severity, sexual functioning, and activity diaries. MMPI subgroup membership, based on a hierarchical cluster analysis in a larger sample, was not predictive of differential treatment outcome. Possible reasons for comparable treatment gains among these subgroups, which previously have been shown to differ on many psychological and behavioral factors, are discussed.

Behavior Therapy↗
PubMed1986

Home placement of automatic external defibrillators among survivors of ventricular fibrillation.

We performed a study to determine how many patients at highest risk for an episode of ventricular fibrillation (those who have already survived such an event) are potential candidates for automatic external defibrillator placement and accepting of such a device in their homes. All VF survivors in King County, Washington, during 1984 were screened for possible enrollment in the study. Of 95 survivors of out-of-hospital VF, 63 (66%) were eligible and of 47 patients approached, 38 (81%) agreed to participate in the study. These findings suggest that approximately half (product of 66% and 81% acceptance rate equals 53%) of VF survivors potentially could use automatic external defibrillators.

Electric Countershock↗