Risk factors for infective endocarditis.
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Aged↗
Biomedical subjects
R P Adams
Publications and source records attributed to R P Adams.
Emergency department hypertension and regression to the mean.
STUDY OBJECTIVE: To evaluate the importance of regression to the mean in the assessment of asymptomatic hypertension in the emergency department. METHODS: This was an historical cohort study of patients in the adult ED of a large urban teaching hospital. THe main outcome was changed in diastolic blood pressure (DBP). Subjects were 195 consecutive hypertensive patients with two sets of vital signs. Patients with specified acute conditions potentially associated with abnormal blood pressure were excluded, as were patients given vasoactive medications. RESULTS: A statistical formula was used to predict the average blood pressure for hypertensive patients, using the observed mean and standard deviation of an all-patient sample. Given a threshold of 90 mm Hg, the expected mean DBP for hypertensive patients was 102.7 mm Hg, compared with an observed value of 104.5 mm Hg. Given an observed correlation coefficient of .73 between first and second measurements, a formula for regression to the mean predicted a spontaneous blood pressure decline of 7.2 mn Hg. A mean decline if 11.6 mm Hg was observed. The decline of 4.4 mm Hg more than expected among asymptomatic hypertensives was similar to the spontaneous decline of 3.7 mm Hg observed in the all-patient sample. CONCLUSION: Patients who present with asymptomatic hypertension in the ED on average experience a spontaneous decline in blood pressure after they arrive. Most of this effect can be explained by regression to the mean. A small amount of this drop may represent attenuation of an initial alerting reaction.
Adult↗
Interim and archival preservation of plant specimens in alcohols for DNA studies.
Three plant species, spinach, juniper and broccoli, were stored in different alcohol solutions, and the DNAs were examined to determine changes in the quality and quantity of DNA over time. The smallest changes in the genomic DNA were found in the samples stored in the lower mol wt alcohols (100% methanol and 100% and 95% ethanol) and when proteinase (Pronase E) was used in the extraction procedure. After 11 months of storage in ethanol, excellent yields of high mol wt DNA were obtained, but only when the procedure utilized Pronase E. The use of proteinase was found to be essential to obtain DNA from preserved specimens of spinach and broccoli. This appears to explain the previous reports of failures to obtain DNA from alcohol-preserved specimens. Vacuum infiltration of ethanol resulted in better DNA preservation than passive infiltration of ethanol.
Alcohols↗
The effects of plant polysaccharides and buffer additives on PCR.
A survey of the inhibitory effects of various plant polysaccharides on PCR amplification of a 974-bp section of rbcL in spinach revealed that most of the polysaccharides tested (arabinogalactan, carrageenan, dextran, gum guar, gum karaya, gum locust bean, inulin, mannan, pectin, starch and xylan) were not inhibitory. In contrast, two of the acidic polysaccharides (dextran sulfate and gum ghatti) were inhibitory. The addition of 0.5% Tween 20 reversed the inhibitory effects of gum ghatti (polysaccharide:DNA ratio of 500:1). The inhibitory effect of dextran sulfate (50:1) could be reversed by the addition of Tween 20 (0.25% or 0.5%), DMSO (5%) or polyethylene glycol 400 (5%), but none of these three additives were effective at a 100:1 ratio of dextran sulfate/DNA.
Biotechnology↗
A simple technique for removing plant polysaccharide contaminants from DNA.
A survey of the inhibitory effects of various plant polysaccharides on DNA restrictions (HindIII and EcoRI) revealed that neutral polysaccharides (arabino-galactan, dextran, gum guar, gum locust bean, beta-glucan, inulin, laminaran, mannan and starch) were not very inhibitory. In contrast, acidic polysaccharides (carrageenan, dextran sulfate, gum ghatti, gum karaya, pectin and xylan) were very inhibitory, even at low concentrations. The Elutip-d (RPC-5 type resin) was evaluated for removal of the inhibitory polysaccharides. Used alone or in combination with a phenol/chloroform wash, it proved effective in removing the polysaccharide so that HindIII digestion was possible, except in the cases of carrageenan and dextran sulfate. In addition, the genomic DNA extracts from live oak (Quercus virginiana) and magnolia (Magnolia grandiflora) were sufficiently purified so that the DNAs could be restricted with both EcoRI and HindIII.
DNA↗
Effect of hyperoxia on substrate utilization during intense submaximal exercise.
Six trained males [mean maximal O2 uptake (VO2max) = 66 ml X kg-1 X min-1] performed 30 min of cycling (mean = 76.8% VO2max) during normoxia (21.35 +/- 0.16% O2) and hyperoxia (61.34 +/- 1.0% O2). Values for VO2, CO2 output (VCO2), minute ventilation (VE), respiratory exchange ratio (RER), venous lactate, glycerol, free fatty acids, glucose, and alanine were obtained before, during, and after the exercise bout to investigate the possibility that a substrate shift is responsible for the previously observed enhanced performance and decreased RER during exercise with hyperoxia. VO2, free fatty acids, glucose, and alanine values were not significantly different in hyperoxia compared with normoxia. VCO2, RER, VE, and glycerol and lactate levels were all lower during hyperoxia. These results are interpreted to support the possibility of a substrate shift during hyperoxia.
Adult↗
Effect of different incremental exercise protocols on the determination of lactate and ventilatory thresholds.
The aerobic threshold (AeT) determined from ventilatory curves occurs at the same oxygen uptake and is independent of the rate of increase of power output in an incremental exercise test. On the other hand, it has been proposed that the AeT determined from blood lactate curves and the anaerobic threshold (AnT) determined from ventilatory curves may vary depending on the exercise protocol. Seven healthy subjects performed two incremental exercise tests to evaluate the effect of the rate of power increment on the AeT and the AnT determined from the break points in both ventilatory and venous blood lactate curves. The protocols on the cycle ergometer consisted of increments of 15 W every min (slow) or every 0.25 min (fast). When the results were expressed as the corresponding oxygen uptake, neither the lactate AeT (slow = 2.662 +/- 0.395 1/min; fast = 2.577 +/- 0.392 1/min; P greater than 0.05) nor the ventilatory AeT (slow = 2.737 +/- 0.426 1/min; fast = 2.583 +/- 0.555 1/min; P greater than 0.05) was significantly affected by the protocols. The lactate AnT (slow = 3.675 +/- 0.610 1/min; fast = 3.683 +/- 0.610 1/min; P greater than 0.05) and the ventilatory AnT (slow = 3.635 +/- 0.665 1/min; fast = 3.823 +/- 0.645 1/min; P greater than 0.05) were also not significantly affected by the protocols. The oxygen uptake corresponding to a blood lactate concentration of 2 mM was significantly higher for the fast protocol (slow = 3.235 +/- 0.735 1/min; fast = 4.005 +/- 0.643 1/min; P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)
Adult↗
Water and ion shifts in skeletal muscle of humans with intense dynamic knee extension.
Six subjects performed one-legged dynamic knee-extension. Blood samples were drawn from the femoral artery and vein, and muscle biopsies were obtained from the quadriceps muscle. Leg blood flow was measured by the thermodilution technique, and 3H-inulin was infused for determination of extra- and intracellular muscle water shifts. During the submaximal work load (S) muscle lactate increased, whereas muscle pH remained almost constant; after maximal exercise (M) the values markedly increased for lactate and decreased for pH. Except for a release of lactate from the exercising muscles, K was continuously released throughout S, and this release increased during M. Immediately when the muscles relaxed, the K release was converted to a K re-uptake. The calculated K loss, based on v- a and flow values, agreed with the decrease in muscle K content from 458 mmol/kg dw at rest to 414 mmol/kg dw at exhaustion (P less than 0.05), as analyzed on the muscle biopsies. Muscle water content increased during S mainly because of an increased extracellular H2O, whereas during M the largest increase occurred in intracellular H2O (H2Oi). Because of the simultaneous K loss and H2Oi increase in the exercising muscle the intracellular [K] was calculated to decrease from 165 mM at rest to 129 mM at exhaustion. This decrease and an increase in extracellular [K] from 4.5 mM at rest to greater than 6.0 mM at exhaustion affects the muscle membrane excitability. Muscle fatigue may thus not only be caused by changes within the cell, affecting energy metabolism or actin-myosin reaction, but may be located at the membrane protecting the cell against overload.
Body Water↗
Dynamic knee extension as model for study of isolated exercising muscle in humans.
In an attempt to approach a system of isolated exercising muscle in humans, a model has been developed that enables the study of muscle activity and metabolism over the quadriceps femoris (QF) muscles while the rest of the body remains relaxed. The simplest version includes the subject sitting on a table with a rod connecting the ankle and the pedal arm of a bicycle ergometer placed behind the subject. Exercise is performed by knee extension from a knee angle of 90 to approximately 170 degrees while flywheel momentum repositions the relaxed leg during flexion. Experiments where electromyographic recordings have been taken from biceps femoris, gastrocnemius, tibialis anterior, and other muscles in addition to QF indicate that only the QF is active and that there is an equal activation of the lateral, medial, and rectus femoris heads relative to maximum. Furthermore, virtually identical pulmonary O2 uptake (Vo2) during and without application of a pressure cuff below the knee emphasizes the inactivity of the lower leg muscles. The advantages of the model are that all external work can be localized to a single muscle group suitable for taking biopsies and that the blood flow in and sampling from the femoral vein are representative of the active muscles. Thus all measurements can be closely related to changes in the working muscle. Using this model we find that a linear relationship exists between external work and pulmonary Vo2 over the submaximal range and the maximal Vo2 per kilogram of muscle may be as much as twice as high as previously estimated.
Adult↗
Dodecandrin, a new ribosome-inhibiting protein from Phytolacca dodecandra.
Dodecandrin, a newly discovered ribosome-inhibiting protein, has been isolated and purified from the leaves of the African endod plant, Phytolacca dodecandra. Dodecandrin has a molecular weight of approx. 29 000. It cross-reacts with antiserum prepared against pokeweed antiviral protein from Phytolacca americana and exhibits similar requirements for antiribosomal activity. It is more basic than pokeweed antiviral protein, and comparison of the first 30 amino-terminal residues of the two proteins reveals 83% homology. This level of homology is greater than that between pokeweed antiviral protein and pokeweed antiviral protein S, another antiviral protein found in P. americana. Such conservatism in sequence, coupled with the high efficiency of the proteins in deactivating ribosomes and with their abundance in plant tissue, suggests that they serve an important function in the life of the plant, probably as a defense against infection.
Immunodiffusion↗
Effect of hyperoxia on metabolic and catecholamine responses to prolonged exercise.
The use of inspired gas mixtures with an oxygen fraction in excess of 0.3 has been associated with a decrease in the gas exchange ratio (R) during prolonged work in humans. It had been hypothesized that the lower R was due to a lower plasma catecholamine concentration caused by the hyperoxia (Med. Sci. Sports 10: 167-170, 1978). We tested this hypothesis by measuring changes in plasma epinephrine and norepinephrine when the subjects were switched from breathing air to 60% O2 (and vice versa) during 40 min of cycle ergometer exercise at 67% maximal oxygen uptake (VO2max). The subject breathed one gas mixture for the first 30 min and was switched to the other in the last 10 min. The order was reversed in the second test. The switch in gas mixtures from air to 60% O2 resulted in a significant reduction in R, heart rate, minute ventilation, blood lactate concentration, and plasma epinephrine concentration (P less than 0.05). The plasma norepinephrine concentration (0.1 greater than P greater than 0.05) and the plasma free fatty acid concentration were not significantly changed. Although the direction of the epinephrine change was consistent with the change in R, the epinephrine change was quantitatively small (20 pg/ml) and of questionable physiological significance. This suggests a direct effect of PO2 on cellular metabolism as one cause of the change in R when the subjects were switched from air to 60% O2.
Epinephrine↗
O2 transport during two forms of stagnant hypoxia following acid and base infusions.
Cardiac output and mean arterial pressure were decreased in two groups of 16 anesthetized paralyzed dogs ventilated by pump. Pericardial tamponade was used in one group, and hemorrhagic hypotension was used in the other. After a 30-min control period and 30 min of circulatory shock by either method, 0.3N HCl was infused into half the dogs in each group and 1.0N NaHCO3 into the other half so that pH was separated by 0.3-0.4 units. The slope of the line relating O2 uptake to total O2 transport (blood flow X arterial O2 concentration) was used to evaluate how well the tissues extracted O2 relative to O2 supply. During the initial shock period before infusion, the slope of the line relating O2 uptake of left hindlimb skeletal muscle to total O2 transport in the limb was almost twice as great as that for the whole body. Acid infusion increased the slope of the whole-body line but did not alter that for the hindlimb. Base infusion, on the other hand, decreased the slope of the line for the limb during hemorrhagic shock but had no other effect. We concluded that acid either improved the distribution of a limiting blood supply to nonmuscle organ systems, or increased tissue capillary PO2 and O2 diffusion by decreasing hemoglobin O2 affinity (HOA), or both. The effect of an increased HOA with base infusion was noticeable in hindlimb skeletal muscle only when volume depletion by hemorrhage presumably greatly increased the normally short intercapillary diffusion distance in muscle.
Animals↗
Total and hindlimb oxygen deficit and "repayment" in hypoxic anesthetized dogs.
Whole-body (WB) and hindlimb [(HL), paw excluded] O2 uptake (VO2) were measured in 26 anesthetized paralyzed dogs while they were ventilated with 9% O2-91% N2 for 15- and 30-min periods and with room air during recovery periods. Ten of the dogs were pretreated with 1 mg/kg propranolol (beta-Blockade). O2 deficit during hypoxia and the excess O2 used during recovery were obtained by assuming that VO2 would have followed the time course described by a line connecting prehypoxic and postrecovery VO2. Amounts of O2 deficit and excess were corrected for changes in O2 stores. O2 excess was seldom as great as O2 deficit in either WB or HL and the two quantities were not obviously related. The rate of HL O2 deficit accumulation decreased with time in hypoxia, whereas WB O2 deficit remained constant. All of HL VO2 was attributed to skeletal muscle so that WB O2 deficit and excess could be partitioned into muscle and nonmuscle portions. The rate of nonmuscle O2 deficit accumulation increased with time, but the nonmuscle portion of O2 excess decreased after the longer hypoxic period. beta-Blockade accentuated but did not change these qualitative relationships. We concluded that neither WB nor HL O2 deficits were fully matched by O2 excess and that regional patterns of O2 deficit accumulation and "repayment" did not necessarily parallel those for WB.
Adrenergic beta-Antagonists↗
A critical value for O2 transport in the rat.
Rat skeletal muscle O2 uptake (VO2) has been reported to be supply dependent even at normal blood flow rates. To find the point at which whole-animal VO2 became dependent on total O2 transport (TOT), intact anesthetized rats were ventilated under hypoxic, normoxic, and hyperoxic conditions while either normovolemic or hypovolemic. In this manner, TOT (cardiac output X arterial O2 content) was varied over a range of 5-80 ml . kg-1 . min-1 . VO2 was measured in a closed-circuit, double servospirometer system. O2 contents were measured in carotid artery and right heart blood. Arterial PCO2, pH, and rectal temperature were kept within normal limits. Above a TOT of 23 ml . kg-1 . min-1, reciprocal changes in O2 extraction and cardiac output maintained VO2 independently of TOT (VO2 = 17.9 +/- 1.3 ml . kg-1 . min-1). Below a TOT of 23 ml . kg-1 . min-1, Vo2 became linearly dependent upon TOT. For TOT between 5 and 16 ml . kg-1 . min-1, VO2 = 0.89 + 0.78 TOT (r = 0.98). These data indicate that above a critical TOT of approximately 23 ml . kg-1 . min-1, VO2 in anesthetized rats does not depend on TOT.
Animals↗
Oxygen uptake, acid-base status, and performance with varied inspired oxygen fractions.
Six subjects rode a bicycle ergometer on three occasions breathing 17, 21, or 60% oxygen. In addition to rest and recovery periods, each subject worked for 10 min at 55% of maximal oxygen uptake (VO2 max) and then to exhaustion at approximately 90% VO2 max. Performance time, inspired and expired gas fractions, ventilation, and arterialized venous oxygen tension (PO2), carbon dioxide tension (PCO2), lactate, and pH were measured. VO2, carbon dioxide output, [H+]a, and [HCO3-]a were calculated. Performance times were longer in hyperoxia than in normoxia or hypoxia. However, VO2 was not different at exhaustion in normoxia compared with hypoxia or hyperoxia. During exercise, hypoxia was associated with increased lactate levels and decreased [H+]a, PCO2, and [HCO3-]a. The opposite trends were generally associated with hyperoxia. At exhaustion, [H+]a was not different under any inspired oxygen fraction. These results support the contention that oxygen is not limiting for exercise of this intensity and duration. The results also suggest that [H+] is a possible limiting factor and that the effect of oxygen on performance is perhaps related to control of [H+].
Acid-Base Equilibrium↗
Ultra-violet treatment of contaminated irrigation water and its effect on the bacteriological quality of celery at harvest.
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Bacteria↗
Selecting a data abstracting service.
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Abstracting and Indexing↗
Gene flow versus selection pressure and ancestral differentiation in the composition of species: analysis of population variation of Juniperus ashei Buch. using terpenoid data.
Twenty-four populations of Juniperus ashei were sampled throughout the range of this taxon and the terpenoids of the foliage were analyzed by gas/liquid chromatography. Population differentiation was investigated by analysis of variance and numerical taxonomy. Three south Texas and one Mexican population clustered together with the rest of the taxon appearing fairly uniform. No evidence was found of hybridization or introgression with other taxa. Disjunct populations in Oklahoma and the Ozarks, which have been genetically isolated from the central population for thousands of years, showed no signs of differentiation nor genetic drift. The present pattern of distribution probably dates from the Pleistocene. The south Texas and Mexican populations appear to be the primitive elements of the species. Populational differences have apparently been maintained in adjacent populations in spite of seemingly large gene flow and conversely, chemical uniformity is being maintained in many disjunct populations where there is little or no gene flow.
Biological Evolution↗