Blood pressure and metabolic effects of 18-oxo-cortisol in sheep

18-Oxo-cortisol (18-oxo-F) has been isolated from the urine of subjects with primary aldosteronism. This study examines the pressor, mineralocorticoid and glucocorticoid effects of 18-oxo-F in conscious sheep--a well studied species for the assessment of the pressor effect of steroid hormones. 18-oxo-F (24 mg/day i.v. for 5 days, n = 3) increased mean arterial pressure MAP (64 +/- 2 mmHg control and 75 +/- 6 mmHg on day 5 P less than 0.001). There was no change in heart rate. Plasma [K+] decreased from a control of 4.3 +/- 0.1 mmol/l control to 2.9 +/- 0.3 mmol/l on day 5 (P less than 0.001). Urinary Na+ excretion decreased on the first infusion day (233 +/- 18 mmol/day control and 124 +/- 20 mmol/day on infusion day 1 P less than 0.001). Urinary K+ excretion was reduced on days 1, 4 and 5 of the infusion. Thus in sheep, 18-oxo-F increased blood pressure associated with in vivo evidence of mineralocorticoid activity.     

Effect of stress on the cardiovascular system activity in operators of predominantly mental work at different times of the day and the working week

The heart rate and systolic and diastolic blood pressures (HR, BP_s, and BP_d, respectively) were measured in controllers of electricity distribution at the beginning and end of 12-h shifts. Hemodynamic parameters were calculated. The stress was assessed with a five-point scale. It was found that the stress of mental work of the operator type activated the functioning of the cardiovascular system (CVS). The CVS reaction was more pronounced and interactive during the first shifts in each block than during the second shifts. The CVS reaction was more pronounced and interactive during day shifts than during night shifts. An increase in stress during the first day shifts was accompanied by a decrease in HR and an increase in minimum BP_d during the shift, in the absence of a BP_s reaction. The minimum levels of all three parameters (HR, BP_s, and BP_d) were increased during the first night shifts, which indicates that the effectiveness of CVS activation in the nighttime was decreased as compared to the daytime. The BP_d is specifically sensitive to the work stress of controllers: its reaction to an increase in stress is classic during the first shifts and inverted during the second night shifts. This reflects exhaustion of adaptation reserves. The HR showed attenuated reactivity during the daytime, but not during the nighttime, when it reacted in the classic way.     

Physiological effects of dynamic hand work in subjects of different age and sex

Thirty untrained subjects (group 1: 10 female, 20-30 years; group 2: 10 female, 36-46 years; group 3: 10 males, 20-30 years) performed dynamic hand work on a hand-grip dynamometer at loads varying from 20 to 100% MVC and three different working frequencies (20, 40, and 60 cpm). The mechanical muscle activity, the iEMG and the R-R interval were measured throughout the exercise. Before and after each exercise, the maximal hand-grip force (MVC) was determined together with the iEMG and the R-R interval. With the loads increasing gradually, the mean values of the duration of the contraction phase and of the iEMG of the four muscles increased in all test groups, but the duration of the rest phase and R-R interval decreased. Through an Analysis of Variance, evidence of systematic differences between the test groups was significant for the R-R interval only, while the effects of the loads (with exception of the rest phase) and of the working frequency proved significant for all parameters. The MVC, the iEMG and the R-R interval measured before and after the exercise did not show significant differences. This indicates that the exercise was not fatiguing.     

Physiological effects of dynamic work on a bicycle ergometer combined with different types of static contraction.

The effects on heart rate, oxygen uptake, and pulmonary ventilation of muscular exercises, including both dynamic contractions, either simple or combined, were studied in 4 male subjects, aged 21 to 23 years. The dynamic work consisted in cycling on an ergometric bicycle at three power levels: 40, 80, and 100 W. The static work consisted in pushing against, pulling and holding with the arms a 6, 9, 12, or 18 kg load. The physiological effects are expressed as cardiac cost (delta HR), oxygen cost (delta VO2) and ventilation cost (delta V). The physiological cost of the combined work increases according to the cycling power and to the isometric load developed. A statistical analysis shows that the costs of combined work are not different from the sum of the costs of the static and dynamic contractions measured separately. Thus, the physiological responses to the combinations investigated are of an additive type.     

Genetic and environmental contributions to age at menarche: Interactive effects of father absence and LIN28B

Substantial research and theory over a number of years have linked father absence to earlier age at menarche (AAM). More recent work has centered on explaining the relative genetic and environmental contributions to this correlation. The purpose of the current study was to evaluate the combined effects of father absence and variation in the LIN28B gene on AAM. A sample of 300 women (age 18–25) successfully genotyped for two LIN28B single nucleotide polymorphisms (SNPs; rs364663 and rs314273) were used to test gene-environment interaction models. Results for both SNPs were consistent with the hypothesis that father absence would attenuate later AAM associated with LIN28B. Genetic index analysis of combined LIN28B SNPs showed that girls with at least one copy of the T/T genotype had later AAM if they were father present. Study strengths and the implications of GxE research for life history models are discussed.     

High and low frequency electroacupuncture analgesia are mediated by different types of opioid receptors at spinal level: a cross tolerance study

Previous studies have shown that rats subjected to low or high frequency electroacupuncture (EA) stimulation release enkephalins or dynorphins respectively to produce analgesia. This conclusion was tested in the present study by using cross tolerance technique for further analysing their receptor mechanisms. The main results were as follows: (1) In rats subjected to 2 Hz EA for 6 h, there was a gradual decrease in the analgesic effect, leading to a state of tolerance to 2 Hz EA analgesia. These rats, however, still responded to 100 Hz EA. Likewise, rats made tolerant to 100 Hz EA were still effective to 2 Hz EA stimulation, showing not significant cross tolerance between 2 Hz and 100 Hz EA analgesia. (2) Rats made-tolerant to 100 Hz EA analgesia showed a diminished response to intrathecal dynorphin A (1-13), a kappa agonist, whereas the analgesic effect of the delta agonist [D-Pen2, D-pen5] enkephalin (DPDPE) remained intact. (3) Rats made tolerant to 2 Hz EA analgesia showed a cross tolerance to DPDPE, but not to dynorphin A (1-13). Results obtained from aforementioned cross tolerance studies suggest that 2 Hz and 100 Hz EA analgesia are mediated by delta and kappa opioid receptors, respectively, at the spinal cord of the rat.     

Childhood asthma in adult life: a further study at 28 years of age.

A group of 323 subjects who had wheezed in childhood and 48 control subjects of the same age were studied prospectively from 7 to 28 years of age. A classification system based on wheezing frequency was found to correlate well with clinical and spirometric features of airway obstruction. The amount of wheezing in early adolescence seemed to be a guide for severity in later life with 73% of those with few symptoms at 14 continuing to have little or no asthma at 28 years. Similarly 68% of those with frequent wheezing at 14 still suffered from recurrent asthma at 28 years. Most subjects with frequent wheezing at 21 continued to have comparable asthma at 28 years. Of those with infrequent wheezing at 21, 44% had worsened at 28 years. Women fared better than men between 21 and 28 with 19% having worse symptoms compared with 28% of men. Treatment at all ages was generally inadequate. The number of smokers among those with asthma was of concern.     

The effects of different levels of heat production induced by diathermy and eccentric work on thermoregulation during exercise at a given skin temperature.

The thermal responses of two healthy male subjects have been studied at the same mean skin temperature (Tsk) during negative work, positive work and positive work in which additional heating was induced by diathermy. The results showed that for a given metabolic heat production (M) rectal (Tre) and oesophageal (Toes) temperatures were higher in negative work and positive work with diathermy than normal control experiments. In resting experiments with diathermy, Toes rose to the same level as when an equal amount of heat was produced metabolically by exercise. In negative work and positive work with diathermy sweat loss (Msw) was higher for a given M and Tsk than found for normal exercise, but in all three forms of work the relationship of Msw to total heat production (H) was identical. During positive work with and without diathermy the differences in Msw could be accounted for by using a previously developed model of relative sweating rate: %Msw = -constant + alphaTre (or Toes) + betaTsk. In negative work, removal of the difference between predicted and observed %Msw required the inclusion of a further factor into the equation based on muscle temperature. The results suggest that the core temperature in exercise rises to meet the requirements of heat dissipation mainly by stimulating Msw and establishing a heat transfer gradient from core to periphery and is not necessarily or uniquely related to M or to the rate of working. The study underlines the usefulness of negative work and diathermy as physiological tools for the further understanding of thermoregulation during exercise.     

Aerobic capacities and blood pressure responses of five different groups in North Sumatra and Aceh at different workloads

In five different groups consisting of athletes (TPG), high school students, men and women (HS), rural group (Arun), and a professional football group (Galatama), the VO2max was determined indirectly, using the cycle ergometer exercise test and Astrand's nomogram. Systolic and diastolic blood pressure was determined using a sphygnomanometer and measured after steady state was reached at each load. The aerobic capacities of the group below 20 years differ significantly between the TPG and all the other groups compared (P less than 0.01). Between the other groups there is a difference in VO2max, though significant differences were only found between the HS (men), Arun group and the HS (women) (P less than 0.01). In the group above 20 years the TPG group have the highest VO2max, and the differences when compared with the HS (men) and Arun groups were significant (P less than 0.01). In the Arun group above 30 years, though a lower values was found in the older age group, significant differences in VO2max were only found between the 30-39 years and the 40-49 years age group (P less than 0.01). Blood pressure responses to different workloads successfully confirmed the results reported by Astrand and Rodahl (1970) and Barnard et al. (1973), but no consistent relationship was found between aerobic capacities and systolic blood pressures.     

Size at birth,maternal nutritional status in pregnancy,and blood pressure at age 17: population based analysis.

OBJECTIVE: To assess the effect of size at birth, maternal nutrition, and body mass index on blood pressure in late adolescence. DESIGN: Population based analysis of birth weight corrected for gestational age, mother''s weight before pregnancy and weight gain in pregnancy, obtained from the Jerusalem perinatal study, and blood pressure and body mass index at age 17, available from military draft records. SETTING: Jerusalem, Israel. SUBJECTS: 10,883 subjects (6684 men and 4199 women) born in Jerusalem during 1974-6 and subsequently drafted to the army. MAIN OUTCOME MEASURES: Systolic and diastolic blood pressures measured at age 17 and their correlation with birth weight, size at birth, mother''s body mass index and weight gain during pregnancy, and height and weight at age 17. RESULTS: Systolic and diastolic blood pressures were significantly and positively correlated with body weight, height, body mass index at age 17, and with mother''s body weight and body mass index before pregnancy, but not with birth weight or mother''s weight gain in pregnancy. CONCLUSION: Variables reflecting poor intrauterine nutrition, including low maternal body mass index before pregnancy, poor maternal weight gain in pregnancy, and being born small for gestational age, were not associated with a higher blood pressure in late adolescence.     

The patterns of changes in physiological and psychophysiological indices in operators with a three-shift working day under various work conditions

In the pulp and paper industry, intense operator activity has been demonstrated to cause fatigue in bleachers and chlorinators at different times of shift work (day, evening, and night). In all the operators, the tests for sensorimotor coordination revealed an increase in the number of errors and changes in the index of coordination; in addition, in chlorinators, fatigue was accompanied by feeling unwell and low activity (the WAM test). The diurnal rhythm of physiological functions against the background of work activity was determined from changes in the body temperature (in bleachers), heart rate, blood pressure, and sensorimotor coordination. The presence of harmful chemical substances (chlorine and chlorine dioxide) in the air negatively influenced the psychophysiological state of the chlorinators.