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Biomedical subjects

R J Rose

Publications and source records attributed to R J Rose.

At least 91 records · Page 5Linked to original sources
PubMed1996

Genetic influences on blood pressure with the cold-pressor test: a twin study.

OBJECTIVES: To determine the genetic and environmental contributions to resting blood pressure, the level of blood pressure during the cold-pressor test and the increase in blood pressure with the cold-pressor test in an adult cohort of normotensive twins. DESIGN AND METHODS: Ninety-one monozygotic and 41 dizygotic normal twin pairs were recruited by advertisement. The mean age was 34 +/- 14 years (mean +/- SD). Systolic blood pressure (SBP), diastolic blood pressure (DBP) and heart rate were measured continuously at the finger (using a Finapres device) and verified at the upper arm oscillometrically (using a Dinamap device) every minute. The cold-pressor test was conducted by immersing the non-dominant hand into cold (< 4 degrees C) water for 2 min. Statistical analysis was performed by using the SPSS program; parameters of the quantitative genetic models were estimated by path-analysis techniques using the LISREL 8 program. RESULTS: Heritability estimates of additive genetic effects were statistically significant for SBP and DBP but not for heart rate during rest and during the cold-pressor test. Furthermore, the path analysis indicated shared as well as specific genetic components both for the blood pressure level at rest and for that during the cold-pressor test. However, the genetic influences on the blood pressure level at rest and on the increase in blood pressure during the cold-pressor test (the blood pressure level during the cold-pressor test minus that during rest) were entirely independent of one another. CONCLUSIONS: A significant genetic covariation exists for SBP and DBP during rest and during the cold-pressor test, as well as a significant genetic variation that is specific to the cold-pressor stress condition. These findings suggest that different genes or sets of genes contribute to blood pressure regulation during rest and to blood pressure reactivity to cold-pressor stress.

Adult↗
PubMed1996

Effect of a warm-up on energy supply during high intensity exercise in horses.

The VO2(max) in racehorses is approximately double that of elite human athletes and the rate of increase in VO2 at the onset of high intensity exercise is much greater than in man. The kinetics of gas exchange are affected by a warm-up prior to exercise in humans, there being a greater aerobic contribution to high intensity exercise after warm-up. Our hypothesis was that a warm-up would increase aerobic energy delivery in racehorses during high intensity exercise. Thirteen fit Standardbred racehorses ran to fatigue at 115% of VO2(max) on a treadmill at 10% slope. Prior to acceleration, horses were exercised either for 5 min at 50% VO2(max) followed by 5 min walk, or walked for 2 min. Samples of expired gas were collected every 10 s during the run for determination of VO2 and VCO2 and measurement of maximal accumulated oxygen deficit (MAOD). Blood lactate concentration was measured 5 min post exercise. We found that with a warm-up, horses had faster kinetics of gas exchange and a greater proportion of their total energy requirement was supplied by aerobic sources. The aerobic contribution to total energy requirement with and without warm-up was, respectively, 79.3 +/- 1.0% and 72.4 +/- 1.7% (P < 0.01). There was also a higher MAOD (P < 0.01) in horses that had not been given a warm-up (mean +/- s.e.m. 34.7 +/- 2.6 and 47.3 +/- 2.6 mLO2eq/kg bwt with and without a warm-up respectively). However, there were no significant differences in total run time or estimated total energy expenditure between the 2 protocols. We concluded that during high intensity exercise to fatigue lasting 1 to 2 min, more than 70% of energy supply is from aerobic energy sources and that this contribution is even greater when the horses have received a warm-up.

Animals↗
PubMed1996

Redistribution of cardiac output in response to heat exposure in the pony.

Radioactive microspheres were used to measure cardiac output and blood flow to most major tissues in 4 ponies at rest in thermoneutral (16 degrees C/60% RH) and mildly hot (41 degrees C/34% RH) environments. In response to heat stress there were increases in cardiac output (2-fold), respiratory frequency (5-fold), blood flow to the skin of the body (3-fold), and limbs (50%), respiratory muscles (2-fold) and the upper respiratory tract (3-fold). Ponies were able to maintain body temperature in the hot environment by increasing blood flow to the tissues involved in heat dissipation, while blood flow to all other tissues remained stable. This was achieved by increasing the cardiac output without need for reduction of blood flow to other tissues.

Animals↗
PubMed1996

Changes in maximum oxygen uptake during prolonged training, overtraining, and detraining in horses.

Thirteen standardbred horses were trained as follows: phase 1 (endurance training, 7 wk), phase 2 (high-intensity training, 9 wk), phase 3 (overload training, 18 wk), and phase 4 (detraining, 12 wk). In phase 3, the horses were divided into two groups: overload training (OLT) and control (C). The OLT group exercised at greater intensities, frequencies, and durations than group C. Overtraining occurred after 31 wk of training and was defined as a significant decrease in treadmill run time in response to a standardized exercise test. In the OLT group, there was a significant decrease in body weight (P < 0.05). From pretraining values of 117 +/- 2 (SE) ml.kg-1.min-1, maximal O2 uptake (VO2max) increased by 15% at the end of phase 1, and when signs of overtraining were first seen in the OLT group, VO2max was 29% higher (151 +/- 2 ml.kg-1.min-1 in both C and OLT groups) than pretraining values. There was no significant reduction in VO2max until after 6 wk detraining when VO2max was 137 +/- 2 ml.kg-1.min-1. By 12 wk detraining, mean VO2max was 134 +/- 2 ml.kg-1.min-1, still 15% above pretraining values. When overtraining developed, VO2max was not different between C and OLT groups, but maximal values for CO2 production (147 vs. 159 ml.kg-1.min-1) and respiratory exchange ratio (1.04 vs. 1.11) were lower in the OLT group. Overtraining was not associated with a decrease in VO2max and, after prolonged training, decreases in VO2max occurred slowly during detraining.

Animals↗
PubMed1995

Intrapair differences in personality and cognitive ability among young monozygotic twins distinguished by chorion type.

We evaluated placentation effects on behavioral resemblance of 44 pairs of monozygotic (MZ) twin children. Tested at ages 4-6, the twins' zygosity and placental type had been determined at their delivery. The sample included 23 monochorionic (MC) and 21 dichorionic (DC) MZ twin pairs: DC-MZ twins result from separation of blastomeres within 72 h of ovulation; MC-MZ twins arise from later duplication of the inner cell mass. Twins were individually administered the McCarthy Scales of Cognitive Ability, while their mothers separately rated each cotwin on an individualized 280-item form of the Personality Inventory for Children (PIC). Absolute differences between MC-MZ cotwins were smaller than those between DC-MZ cotwins for all 20 PIC scales, significantly so for 3 of 4 factor scales, 8 of 12 clinical scales, and 2 of 4 validity/screening scales from the PIC; in contrast, no consistent differences in intrapair resemblance of mono- and dichorionic MZ twins were found for the McCarthy Scales. The chorion differences found in the PIC data cannot be due to genetic differences, because all pairs are monozygotes; nor are they associated with differences in parity, gestational age, birth weight, maternal education, palmar dermatoglyphic asymmetry, or maternal knowledge of chorion type. We interpret our findings as suggestive evidence that variation in timing of embryological division, with effects on MZ twins' placental vasculature, has significant consequences for some dimensions of their behavioral development, as well.

Child↗
PubMed1995

Comparison of bronchoalveolar lavage findings and measurements of gas exchange during exercise in horses with poor racing performance.

Twenty-four Thoroughbred and twelve Standardbred racehorses aged between 2 and 6 years, presented for reported poor racing performance, underwent clinical exercise testing. During the last 10 s of exercise at each speed throughout an incremental speed exercise test on a treadmill inclined at a 10% slope, samples of arterial blood and expired gases were collected. Maximum oxygen uptake and the partial pressures of oxygen and carbon dioxide in arterial blood were determined. These values were compared between the two breeds of horses and also with reference to cytological findings of bronchoalveolar lavage samples, including neutrophil, erythrocyte and haemosiderophage percentage and the total nucleated cell concentration. The results revealed an inverse relationship (Spearman R = -0.45, p < 0.05) between the total nucleated cell count in bronchoalveolar lavage samples and arterial oxygen partial pressure during exercise at 11 m.s(-1). This result suggests that subclinical pulmonary disease may be a more important cause of poor racing performance than previously thought. Also of note was a positive correlation (Spearman R = 0.50, p < 0.05) between maximum oxygen uptake and the percentage of erythrocytes.

Journal Article↗
PubMed1995

The effects of tonicity, glucose concentration and temperature of an oral rehydration solution on its absorption and elimination.

Effects of different tonicities, glucose concentrations and temperatures of an oral rehydration solution (ORS) on its uptake and elimination in resting horses were studied. Fluid and electrolyte deficits similar to those occurring during prolonged exercise were induced by the administration of 1 mg/kg bwt of frusemide i.m., 3 h prior to the ORS. Fluid was administered via nasogastric tube at a volume equivalent to 4% bodyweight, which approximated diuretic induced losses. The uptake of fluid was evaluated by changes in haematocrit (PCV) and plasma total protein concentration (TP). Changes in electrolyte balance were studied by measurements of plasma and urinary electrolyte concentrations while changes in bodyweight, urine volume and faecal water content were used to estimate retention of the administered fluids. Changes in acid base status were assessed from venous blood bicarbonate values. Fluid tonicity had a major effect on the uptake and elimination of the ORS. The hypertonic fluid (628 mOsm/kg bwt) was less rapidly absorbed and resulted in more rapid fluid and electrolyte excretion than the isotonic (314 mOsm/kg bwt) and hypotonic (water) fluids. The inclusion of glucose did not enhance the absorption of the ORS, although fluids containing higher concentrations of electrolytes resulted in more rapid elimination of fluid in urine. There was a direct relationship between higher concentrations of sodium in the ORS, plasma sodium values and osmolality. Fluid temperature (5, 21 and 37 degrees C) had no demonstrable effect on absorption of the ORS and elimination of fluids post administration. We concluded that while glucose concentration and fluid temperature have minimal effects on fluid absorption and elimination, fluid tonicity was a key element in the uptake and elimination of orally administered fluid. These findings are likely to be of relevance when administering ORS in association with exercise.

Absorption↗
PubMed1995

Equine sweat composition: effects of adrenaline infusion, exercise and training.

Significant alterations in plasma electrolyte concentrations have been reported in horses following prolonged exercise, resulting from loss of hypertonic sweat. Sweat was collected from 10 horses undergoing a 10 week training programme; 5 at moderate intensity, to speeds of 10 m/s and 5 at low intensity, to speeds of 5 m/s. Sweat was collected from 2 sites in response to a submaximal exercise test (30 min at 50% VO2max and during an adrenaline infusion (dose mean +/- s.d.; 0.3 +/- 0.05 g/kg over 30 min). Sweat samples were analysed for sodium, chloride, potassium, protein, magnesium, calcium and urea concentrations. Sweat produced in response to exercise and adrenaline infusion was hypertonic and showed no significant differences in composition following training. However, the [NaCl] of sweat rose with increased duration of sweating. Sweat produced in response to adrenaline infusion was more dilute than that produced in response to exercise, which may be related to sympathetic outflow during exercise.

Animals↗
PubMed1995

Maximal accumulated oxygen deficit in thoroughbred horses.

Thoroughbred horses have a high aerobic capacity, approximately twice that of elite human athletes. Whereas the aerobic capacity of horses can be accurately measured, there have been no measurements of anaerobic capacity. The aim of this study was to determine whether maximal accumulated O2 deficit (MAOD) could be measured in horses and used as an estimate of anaerobic capacity, as in human athletes. Six fit Thoroughbred horses were used with the exercise protocol utilizing a treadmill set at a 10% incline. O2 uptake VO2 was measured via an open-flow system for seven submaximal speeds (3-9 m/s), and maximal VO2 (135 +/- 3 ml.kg-1.min-1) was determined. The horses performed three tests at 105 and 125% and six tests at 115% of maximal VO2. The MAOD test was performed with the treadmill accelerated rapidly from 1.5 m/s (mean acceleration time 8 s) to the calculated speed (11-14 m/s). VO2 was measured every 10 or 15 s, and the test ended when the horse no longer kept pace with the treadmill. The mean run times were 165, 98, and 57 s for intensities of 105, 115, and 125% maximal VO2. The mean MAOD values were 31 +/- 2, 30 +/- 1, and 32 +/- 2 (SE) ml O2 eq/kg for the three intensities (P > 0.05). The proportion of energy derived from aerobic and anaerobic sources was calculated from the difference between calculated O2 demand and the VO2 curve. There was no correlation between MAOD and maximal VO2.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Effect of treadmill incline and speed on metabolic rate during exercise in thoroughbred horses.

We examined the effect of treadmill speed and incline on O2 uptake (VO2), CO2 production, heart rate (HR), plasma lactate concentration, economy of locomotion, stride frequency, and stride length. A further aim was to examine the relationships between HR and VO2 and lactate and VO2 and whether these relationships vary with alterations in treadmill incline. The experiment was a latin square design, using five horses and five treadmill inclines (0, 2.5, 5.0, 7.5, and 10.0%). Fit Thoroughbred horses exercised for 4 min at 3 m/s at 0% slope, after which the treadmill was set to the allocated incline. Speeds tested ranged from 1 to 13 m/s. The relationships of VO2 and CO2 production with speed were curvilinear at 0 and 2.5% and linear at 5, 7.5, and 10% inclines. There was a linear relationship of HR and speed with a significant effect of incline. The plasma lactate concentration increased exponentially with speed, and there was a significant effect of incline. Stride length increased linearly and stride frequency increased in a curvilinear manner with speed but there was no effect of incline. There were linear relationships of HR with VO2 and HR with VO2 when expressed as percentage of maximum VO2 and maximum HR that were not affected by incline. The O2 cost of exercise on a 10% incline was approximately 2.5 times that for exercise on the flat. The strong relationship between the percentages of maximum HR and maximum VO2 indicates that over a wide range of exercise intensities the relative VO2 can be accurately predicted from measurements of HR.

Animals↗
PubMed1995

Selective brain cooling in the horse during exercise and environmental heat stress.

Five horses were exercised on a treadmill [to central blood temperature (Tcore) approximately 42.5 degrees C]. Three of those horses were heated at rest in a climate room (53 degrees C, 90% relative humidity) (to Tcore approximately 41.5 degrees C). Temperatures were measured in the rectum, hypothalamus (Thyp), cerebrum, and cavernous sinus (Tsinus), on the skin of the head and midside, and Tcore. When Tcore increased above 38.5 degrees C, Thyp remained 0.6 +/- 0.1 degree C (SE) lower during heat exposure and 1 +/- 0.2 degrees C lower during exercise. During heat exposure, Tsinus was 2.2 +/- 0.4 degrees C below Tcore, and during exercise, Tsinus was 5 +/- 0.9 degrees C below Tcore. Upper respiratory tract bypass during exercise in one horse resulted in substantial reductions in Tcore-Thyp to 0.4 +/- 0.3 degrees C and Tcore-Tsinus to 0.9 +/- 0.2 degrees C. Thus the horse, a species without a carotid rete, can selectively cool the brain during exercise or heat exposure; this occurs, at least in part, via cool blood within the cavernous sinus, presumably resulting principally from cooling of venous blood within the upper respiratory tract.

Animals↗
PubMed1995

Common genetic influences on BMI and age at menarche.

Genetic influences on variability of body weight and onset of menarche are well known. To investigate the genetic and environmental contributions to the association of body weight with onset of menarche, we studied Finnish twins from consecutive birth cohorts (the FinnTwin16 study) ascertained from the national population registry, which identifies nearly 100% of all living twins. Baseline questionnaires were mailed to the twins within 60 days of their sixteenth birthday and later to older sibs of the twins. Pairwise response rates (approximately 85% across gender and zygosity) and 30 months of data collection yielded results from 1283 twin pairs. The questionnaires included a survey of health habits and attitudes, a symptom checklist, MMPI personality scales, and a survey of relationships with parents, peers, and the co-twin. Age at menarche was reported by 468 monozygotic (MZ) girls, 378 girls from like-sex dizygotic (FDZ) pairs, 434 girls from opposite-sex (OSDZ) pairs, and 141 older female sibs of the twins. The one-month test-retest reliability of age at menarche in an independent sample (N = 136) of 16-year-olds from a national survey was 0.96. Girls from OSDZ pairs had a significantly higher mean age at menarche (13.33 yr) than FDZ girls (13.13 yr) (difference, 0.20 yr; 95% confidence interval, 0.05-0.35). The MZ correlation for age at menarche was 0.75, the DZ correlation was 0.31, and the sib-twin correlation was 0.32. A bivariate twin analysis of age at menarche and body mass index (wt/ht2) indicated that 37% of the variance in age at menarche can be attributed to additive genetic effects, 37% to dominance effects, and 26% to unique environmental effects. The correlation between additive genetic effects on age at menarche and body mass index was 0.57, indicating a substantial proportion of genetic effects in common.

Adolescent↗
PubMed1994

Replication of asymmetry of a-b ridge count and behavioral discordance in monozygotic twins.

We have replicated an earlier study (Rose et al., Behav. Genet. 17, 125-140, 1987) relating dermatoglyphic asymmetry to intrapair discordance in a completely new sample of monozygotic (MZ) twins. Consistent results were observed for at least 31 of 37 Minnesota Multiphasic Personality Inventory (MMPI) scales tested in the two samples. Intrapair differences were confirmed to be greater in 28 MZ pairs with asymmetric palmar a-b ridge counts than in 29 MZ pairs with little or no a-b asymmetry for at least 15 scales. We also examined longitudinal stability over a 4 to 5-year period for six MMPI scales and found suggestive evidence in three scales for greater test-retest instability in twin pairs asymmetric for a-b ridge count. The results offer new evidence for our hypothesis that an asymmetric a-b ridge count may identify individuals who are poorly buffered from developmental noise, but analyses of symmetric and asymmetric a-b ridge counts in nontwin subjects are required to extend and test the hypothesis further.

Adult↗
PubMed1994

Gait and respiration in standardbred horses when pacing and galloping.

The relationship between gait and the respiratory response to exercise was examined in five standardbred racehorses which exercised on a treadmill at a pace and a gallop. After an initial warm-up, respiratory rate and stride frequency were measured after one and two minutes of treadmill exercise at 80 per cent of maximal oxygen consumption (VO2max), after one minute at 100 per cent VO2max and after two minutes at 100 per cent VO2max (galloping horses only). Exercise at 100 per cent VO2max continued until the horses showed signs of fatigue. Arterial blood was collected during exercise and when they were fatigued for the measurement of oxygen and carbon dioxide tensions, haemoglobin saturation and pH. Venous blood temperature was also recorded. The mean (SE) time to signs of fatigue was significantly (P < 0.05) less in the pacing horses (7.2 [0.4] minutes) than in the galloping horses (8.0 [0.4] minutes). The mean (SE) resting PCO2 was 47.7 (1.9) torr. During the pacing and galloping exercises at 80 per cent and 100 per cent VO2max the PCO2 remained in the range of 41.1 to 66.8 torr, despite concurrent hyperthermia and acidosis. The PCO2 during exercise was not significantly dependent on gait or exercise intensity. The PO2 was significantly higher in pacing horses during exercise at 80 per cent VO2max (111 [7] vs 96 [6] torr). The mean (SE) arterial blood pH decreased from 7.428 (0.025) during pacing at 5 m sec-1 to 7.250 (0.042) when the horses were fatigued.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Blood lactate disappearance after maximal exercise in trained and detrained horses.

The influence of training on blood lactate concentrations during treadmill exercise and a 40-minute inactive recovery period was examined in seven trained and seven detrained thoroughbred horses. Lactate concentrations were measured in venous blood collected at the end of each exercise state, and at intervals for 40 minutes afterwards. Measurements were made of maximum oxygen uptake (VO2max, ml kg-1 min-1), VLA4 (velocity at which blood lactate concentration was 4 mmol litre-1); LA8 (lactate concentration [mmol litre-1] during exercise at 8 m sec-1), peak lactate (highest lactate concentration after exercise), LA40 (lactate concentration 40 minutes after exercise), the time of peak lactate concentration (minutes after exercise) and the rate of disappearance of blood lactate (Rtd). The trained horses had a significantly lower LA8 (2.1 +/- 0.1 vs 6.5 +/- 1 mmol litre-1, P < 0.01), higher VLA4 (9.8 +/- 0.2 vs 5.8 +/- 0.6 m sec-1, P < 0.01) and higher VO2max (156.3 +/- 3.8 vs 107.1 +/- 3.9 ml kg-1 min-1, P < 0.001). The value of Rtd and the time of peak lactate concentration were not significantly different.

Animals↗
PubMed1994

A developmental genetic analysis of adult personality: extraversion and neuroticism from 18 to 59 years of age.

Developmental genetic analyses were conducted on Extraversion (E) and Neuroticism (N) scale scores from nearly 15,000 male and female Finnish twins, ages 18-53 at baseline, who were tested on 2 occasions, 6 years apart. Significant genetic effects on both traits were found, at all ages, in men and women, on each measurement occasion. For E, heritability was invariant across sex but decreased from late adolescence to the late 20s, with a smaller additional decrease at about 50 years of age. Heritability for N also decreased from late adolescence to late 20s and remained stable thereafter. For all ages after the early 20s, heritability of N was significantly higher among women. Means for E and N were sex-dependent and, apparently, influenced by cohort and time of assessment, as well as by age. There was little evidence of new genetic contributions to individual differences after age 30; in contrast, significant new environmental effects emerged at every age.

Adolescent↗