A 33-yr follow-up of peak oxygen uptake and related variables of former physical education students

Åstrand, Per-Olof, Ulf Bergh, and ÅsaKilbom. A 33-yr follow-up of peak oxygen uptake and relatedvariables of former physical education students. J. Appl. Physiol. 82(6): 1844-1852, 1997.In 1949, 27 female and 26 male physical education students were studied at amean age of 22 and 25 yr, respectively. They were restudied in 1970 and1982. Measurements included oxygen uptake, heart rate, and pulmonaryventilation during submaximal and maximal exercise on a cycle ergometerand treadmill. After 21 yr, peak aerobic power was significantlyreduced, from 2.90 to 2.18 l/min and from 4.09 to 3.28 l/min for womenand men, respectively. After another 12 yr, the 1970 maxima were notreduced further. From 1949 to 1982 there was a decrease in peak heartrate from 196 to 177 beats/min in women and from 190 to 175 beats/minin men (P < 0.05). Highest pulmonaryventilation did not change significantly. At an oxygen uptake of 1.5 l/min, the heart rate was the same in 1949 as in 1982. In conclusion,the physical fitness level of the subjects was well above average forthese ages. From 1970 to 1982 there was no decline in the average peakaerobic power, a finding possibly related to increased habitualphysical activity.

     

A comparison of normalization methods for high density oligonucleotide array data based on variance and bias

MOTIVATION: When running experiments that involve multiple high density oligonucleotide arrays, it is important to remove sources of variation between arrays of non-biological origin. Normalization is a process for reducing this variation. It is common to see non-linear relations between arrays and the standard normalization provided by Affymetrix does not perform well in these situations. RESULTS: We present three methods of performing normalization at the probe intensity level. These methods are called complete data methods because they make use of data from all arrays in an experiment to form the normalizing relation. These algorithms are compared to two methods that make use of a baseline array: a one number scaling based algorithm and a method that uses a non-linear normalizing relation by comparing the variability and bias of an expression measure. Two publicly available datasets are used to carry out the comparisons. The simplest and quickest complete data method is found to perform favorably. AVAILABILITY: Software implementing all three of the complete data normalization methods is available as part of the R package Affy, which is a part of the Bioconductor project http://www.bioconductor.org. SUPPLEMENTARY INFORMATION: Additional figures may be found at http://www.stat.berkeley.edu/~bolstad/normalize/index.html     

Thermoregulatory shivering during exercise

Three subjects with lowered internal body temperatures performed brief bouts of bicycle ergometer exercise at 150 and 200 W. Oxygen uptake during exercise was consistently greater than that required by the working muscles, the increase being the result of the additional cost of shivering. Increases in metabolism during exercise above control levels were inversely proportional to internal temperature (with skin temperature constant) below a given internal temperature threshold. Observations of intense shivering during exercise which is proportional to lowered internal temperature in the same manner as during rest provides further evidence against the concept of a decrease in the thermoregulatory set point during exercise in man.     

Endocrine and behavioral traits in low-avoidance Sprague-Dawley rats

In the present series of experiments, we have examined the endocrine profile of two stable colonies of Sprague-Dawley rats, here labeled Stock A, and Stock B, differing markedly in their ability to acquire a conditioned avoidance response. On separate occasions, the animals were subjected to five daily sessions (approximately 20 trials per 15 min session) of conditioned avoidance training, measurements of startle reactivity to an auditory stimulation and open-field spontaneous locomotor activity observations. The experiments were concluded by taking blood samples for later analysis of plasma glucose and plasma levels of the following hormones: insulin, gastrin, CCK, glucagon, somatostatin, oxytocin and corticosterone. The low-performing Stock B animals were characterized by [1] being more reactive to sensory stimulation: higher startle amplitude and shorter startle latency; [2] having higher plasma insulin and corticosterone levels, whereas plasma gastrin and oxytocin were significantly lowered and a strong tendency for a decrease also in plasma CCK. There were no differences in spontaneous locomotor activity between the two substrains. Taking total variability in avoidance performance into account, there was a statistically significant positive correlation between plasma oxytocin, as well as gastrin, levels and avoidance performance. The evidence obtained here, and in other laboratories, suggests that the Stock B animals display hormonal changes indicative of a submissive-defensive reaction pattern. Thus, the avoidance acquisition deficits displayed by the present Sprague-Dawley stocks A and B, are in all probability caused by emotional reactions when challenged with external stimuli requiring active responding.