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Biomedical subjects

K E Klein

Publications and source records attributed to K E Klein.

At least 19 recordsLinked to original sources
PubMed1995

Thyroid function in non-growth hormone-deficient short children during a placebo-controlled double blind trial of recombinant growth hormone therapy.

GH treatment in GH-deficient children has been reported to cause decreases in serum T4 and TSH and an increase in serum T3. We sought to determine whether GH treatment alters thyroid function in non-GH-deficient short children. Twenty children (18 boys) were followed for 12 months while receiving either GH (Humatrope, Eli Lilly; 0.074 mg/kg, sc, 3 times/week; n = 9) or placebo (n = 11). Total T4, free T4, T3, and TSH were measured every 6 months and in 12 children also at 1, 2, 3, and 9 months. A TRH test and measurement of nocturnal TSH surge were performed at baseline and after 6 months of treatment in 19 subjects. There were no significant differences at baseline in the clinical features between the placebo and GH groups. Total T4, free T4, T3, and TSH levels did not significantly differ between the placebo and GH groups at baseline and at 1, 2, 3, 6, 9, and 12 months. There were no significant differences between the two groups in TSH response to TRH or nocturnal TSH surge. Although an early transient effect of GH treatment could not be excluded, we conclude that GH treatment for 12 months does not produce sustained alterations in thyroid function in non-GH-deficient children.

Body Height↗
PubMed1992

Problem solving and suicidality among prison inmates: another look at state versus trait.

This research examines the relationships between means-ends problem solving and suicidality among adult male prison inmates in light of new evidence based on inpatient and college student populations suggesting that state, rather than trait, vulnerabilities may be responsible for problem-solving deficits and differences. Using the Means-Ends Problem-Solving Procedure (MEPS) with 93 state prison inmates, we found that among inmates with a history of parasuicide, current suicidality did not affect problem-solving performance. We further found that among nonsuicidal inmates, parasuicide history had no effect on problem solving or affect-suicidality measures. Although these results support new research suggesting that trait problem-solving deficits are not causally linked to suicidality, they raise questions about the potentially unique relationships among suicidality, problem solving, depression, and hopelessness in incarcerated populations.

Adult↗
PubMed1986

Hemodynamic response to LBNP following 2 hours HDT (-6 degrees).

Central hemodynamics have been determined during stepwise decreasing LBP in head-down tilt (HDT) of -6 degrees. Measurements were performed on eight healthy volunteers using right heart catheterization. During LBNP, pressures in the right atrium, pulmonary artery, and pulmonary capillary (preload) decreased in parallel with the increase of negative pressure applied to the lower part of the body. Similarly, stroke volume and cardiac output decreased with increasing negative pressure. Heart rate moderately increased (30%) as well as total peripheral resistance. The left ventricular function curve was shifted downward and to the left during LBNP indicating hypovolemia with no evidence of decreased contractility. Cardiac dimensions determined by echocardiography changed in a similar way as those obtained by invasive measurements. There was a very close correlation between stroke volume determined by thermodilution and by echocardiography. Plasma norepinephrine and dopamine tended to increase at the end of LBNP. Echocardiography proved a useful and reliable approach to hemodynamic measurement during LBNP and is recommended for analysis of hemodynamic parameters during zero G and Gz simulation.

Adult↗
PubMed1984

Central hemodynamics during zero gravity simulated by head-down bedrest.

Central hemodynamics during head-down tilt of -6 degrees lasting for 2 h were studied using catheterization of the pulmonary artery. M-mode echocardiography was performed simultaneously. Significant increases occurred for pressures in the right atrium, pulmonary artery in pulmonary wedge position, and for pulmonary vascular resistance. Cardiac and stroke volume index, heart rate, mean arterial pressure, and total systemic resistance remained constant throughout the exposure time. Constancy was also observed for echocardiographic measures of cardiac dimensions. It is concluded that head-down tilt leads to an increase of preload without any evidence of disturbed left ventricular function. No distinct time course of hemodynamic variables could be seen. Echocardiography proved a useful method to study cardiovascular adaptations during head-down tilting.

Adaptation, Physiological↗
PubMed1983

Flight, flight duty, and rest times: a comparison between the regulations of different countries.

Flight time, flight duty limitations, and rest requirements are compared between the regulations from nine different countries. Twelve factors are identified which played a role in formulating restrictions and criteria. Duration of flight duty and crew augmentation are the factors considered by most countries; time of day, night flight, night sleep, and time zones are the factors least considered. Conformity exists in the necessity to prescribe maximum permissible flight or duty times and minimum rest requirements on a daily basis. Agreement was also observed in grading the standards according to more or less fatiguing conditions. Six out of nine regulations define night hours, but fail to agree upon beginning, end, and duration of night. All countries but one limit flying hours on a monthly and yearly basis, although the limits diverge. A brief outline of the German provisions is presented as an example for a compact and practicable regulation.

Australia↗
PubMed1983

A model for prediction of resynchronization after time-zone flights.

Utilizing experimental data from three flight studies, a concept was developed which allows appraising average resynchronization for any day after arrival in a new time-zone. The course of adaptation is nonlinear and can be mathematically represented by an exponential function. The model predicts higher initial resynchronization rates when more time zones are crossed, but total time for complete reentrainment is essentially the same and, thus is independent of the number of time-zones. The equation derived from experimental data is converted into an e-function and the resulting time constants are presented as they evolved for different functions and flight directions.

Aerospace Medicine↗
PubMed1977

Athletic endurance training - advantage for space flight?: The significance of physical fitness for selection and training of spacelab crews.

While intensive physical exercise has been part of the conditioning of astronauts and consmonauts for spaceflights, its benefits have been questioned. After reviewing the pertinent literature, it is concluded that the morphological and functional changes obtained with athletic endurance training are rather specific and of no general advantage for the tolerance to space stresses. Particularly during gravitational loads, in the relaxed subject, these changes allow a more pronounced shift of fluid into the lower extremities, with the possible consequence of a reduced tolerance. This unfavourable response, obviously, is accentuated through immersion and weightlessness. The aerobic work capacity is also more impaired in athletes. Based on these conclusions, recommendations for crews and passengers of future Spacelab missions are given with respect to selection and pre-and in-flight physical exercise.

Acceleration↗
PubMed1976

Air operations and circadian performance rhythms.

This paper reviews experimental results and pertinent data from the literature on circadian behavioural rhythms and their modifications through various factors. It relates them to the operation of aircrews "round the clock" and on transmeridian routes and discusses some possibilities of an appropriate scheduling.

Aerospace Medicine↗
PubMed1975

[Behavior of the human organism in time zone flights. 2. Sequelae of desynchronization].

The responses of the human organism to time zone flights are reviewed. The physical and biological principles which are connected with dysrhythmic phenomena following shifts of environmental time cues are demonstrated. Quantity and quality of desynchronotic symptoms of psychophysiological functions are described and their significance for performance ability and health of the air traveller, in particular with respect to the possibility of pathogeneous effects, are discussed.

Aerospace Medicine↗