Targeting stopwords for quality assurance of SNOMED-CT.

Objective: We assess the potential of exploiting stopwords in biomedical concept names to complete the logical definitions of concepts that are not sufficiently defined.

Methods: Concepts containing stopwords are selected from the Disorder hierarchy of Systematized NOmenclature of MEDicine (SNOMED-CT). SNOMED-CT consists of two types of concepts: Fully Defined (FD) concepts which are sufficiently defined and Partially Defined (PD) concepts which are not sufficiently defined.

Blood oxygen saturation measured in the presence of a mixture of cyclopropane, sulfur hexafluoride, and ethane.

Some anesthetic gases interfere with the determination of blood O2 values. We evaluated, for its potential for such interference, a gas mixture containing (v/v) approximately 70% ethane, 20% sulfur hexafluoride, and 10% cyclopropane, as is currently used in trace amounts to determine ventilation-perfusion (v/Q) ratios. Normal human blood samples were first tonometered with control gas mixtures containing (v/v): (1) 20.

Operation Everest II: neuromuscular performance under conditions of extreme simulated altitude.

The force output of the ankle dorsiflexors was studied during a 40-day simulated ascent of Mt. Everest in a hypobaric chamber; both electrically activated and maximal voluntary contractions (MVCs) were employed. The purpose of this study was to establish whether, under conditions of progressive chronic hypoxia, there was a decrease in muscle force output and/or increased fatigability.

Symptomatology during hypoxic exposure to flame-retardant chamber atmospheres.

Hypoxia was studied in 12 men during 63-h exposures to 17 and 13% O2, with the subjects serving as their own controls by repeating the measurements in 21% O2. All test atmospheres were contaminated with 0.9% CO2 to simulate the condition of living aboard submarines.

Operation Everest II: comparison of four instruments for measuring blood O2 saturation.

The bias and precision of four different methods for determining O2 saturation (SO2) were evaluated during a study of hypobaric hypoxia conducted with seven male subjects exposed progressively over a 40-day period to simulated altitudes from sea level (760 Torr) to 8,840 m (240 Torr). SO2 of arterial and mixed venous blood samples were measured with the Instrumentation Laboratory 282 CO-oximeter (CO-OX), the Radiometer ABL-300 (ABL), and the Lex-O2-Con-K (LEX). Noninvasive measurements of arterial SO2 were made with a Hewlett-Packard 47201A ear oximeter (EAR-OX).

Acute mountain sickness at 4500 m is not altered by repeated eight-hour exposures to 3200-3550 m normobaric hypoxic equivalent.

A lightweight device, designed to supply inspired air at 12.8% O2 concentration (PO2 equivalent to 3960 m altitude) by recirculating a portion of each expired breath after CO2 removal, was tested at sea-level for its ability to induce altitude acclimation. Twelve young men (experimental group) breathed from the device for 7.

Effect of dexamethasone on symptoms of acute mountain sickness at Pikes Peak, Colorado (4,300 m).

In a previous controlled study, dexamethasone (DEX) was shown to prevent acute mountain sickness (AMS) during exposure to simulated high altitude. To determine the effect of DEX during actual altitude exposure, 16 young men were treated with either DEX (4 mg every 6 h) or placebo for 48 h prior to and 48 h after being rapidly transported from sea level to the summit of Pikes Peak, CO (4,300 m). Symptoms of AMS were evaluated twice daily at Pikes Peak using the Environmental Symptoms Questionnaire and a clinical assessment.

Respiratory response and muscle function during isometric handgrip exercise at high altitude.

The purpose of this investigation was to determine if the hyperventilatory response to fatiguing isometric exercise at sea level could predict resting ventilation and acute mountain sickness (AMS) at 4300 m altitude. Exercise consisted of four successive endurance handgrips held to complete fatigue at 40% of maximum isometric handgrip strength (MHS). There was no relationship between the magnitude or pattern of exercise-induced hyperventilation at sea level and the severity of AMS later at altitude.

The influence of cardiorespiratory fitness on the decrement in maximal aerobic power at high altitude.

There are conflicting reports in the literature which imply that the decrement in maximal aerobic power experienced by a sea-level (SL) resident sojourning at high altitude (HA) is either smaller or larger for the more aerobically "fit" person. In the present study, data collected during several investigations conducted at an altitude of 4300 m were analyzed to determine if the level of aerobic fitness influenced the decrement in maximal oxygen uptake (VO2max) at HA. The VO2max of 51 male SL residents was measured at an altitude of 50 m and again at 4300 m.

Procedures for the measurement of acute mountain sickness.

Although acute mountain sickness (AMS) has been studied for well over a century, a standard measure or index of the degree of illness for use in experimental research does not exist. This paper outlines a definition and procedures for an operational measurement of AMS using the Environmental Symptoms Questionnaire (ESQ). After 58 men completed over 650 ESQs during a stay of 1-3 weeks atop Pike's Peak (4300 m), factor analysis produced nine distinct symptom groups, with two factors representing AMS.

Height, weight, percent body fat, and indices of adiposity for young men and women entering the U.S. Army.

The purpose of this investigation was to describe the height (H), weight (W), and percent body fat (%BF) of young men and women (ages 17-35 years) entering the U.S. Army and to determine an index of adiposity that fit criteria described in the literature.

Phenytoin: ineffective against acute mountain sickness.

Phenytoin sodium was evaluated for its effect on the development and intensity of acute mountain sickness (AMS) because of its ability to reduce intracellular Na+ concentrations in brain and thereby minimize any tendency to increase cellular volume, a hypothetical cause of AMS. Six men aged 19-35 were exposed to approximately 4600 m altitude in a hypobaric chamber for 52 h on two occasions separated by 10 d at sea level. Subjects received wither phenytoin or placebo for 18 h before (700 mg, divided dose) and throughout (100 mg t.

Isometric fatigue induced by different levels of rhythmic exercise.

Three subjects were trained in leg extensor isometric contractions and in cycling. They then cycled for three consecutive bouts, each of 2.75 min at a constant level of VO2, from 20 to 80% VO2 max.

Influence of posture on isometric fatigue.

The isometric strength of four trained subjects was unaltered by changes in posture. But the endurance of an isometric contraction held to fatigue at 25 and 40% of the maximum voluntary contraction (MVC) was 20% greater in the sitting than in the recumbent posture. This difference was abolished when the exercise was performed with the arm's circulation arrested.

Comparison of physiological responses of women and men to isometric exercise.

The volunteers for this study were 83 women, aged 19-65 yr, drawn from several different occupations. Three minutes after exerting maximal handgrip strength (MVC) each subject held a tension of 40 percent MVC to fatigue. Blood pressures and heart rates were measured before, during, and after the endurance of contraction.

Differentiated ratings of perceived exertion during physical conditioning of older individuals using leg-weight loading.

Use of leg weights for physical conditioning was evaluated in 8 middle-aged male Ss; four Ss of similar age served as a control group. Pre- and post-training evaluation consisted of heart rate and oxygen uptake responses to five submaximal work loads which involved either level walking or cycling. Differentiated ratings of perceived exertion elicited for each work load were: a local muscular rating; a central or cardio-pulmonary rating; and an over-all or general rating.

The assessment of the static component in rhythmic exercise.

A new approach has been devised to assess the "static component" of dynamic exercise. This technique involves the measurement of the isometric endurance of muscles which have just taken part in rhythmic exercise and depends on the repeatability of trained subjects in isometric effort. The premise is that isometric endurance will be inversely related to the static component of the preceeding dynamic exercise.