Comparative study on determination of plasma thyroid hormones by chemiluminescence and electrochemiluminescence immunoassay methods in sheep

The aim of this study was to compare plasma thyroid hormone concentrations by both chemiluminescence (CLIA) and electrochemiluminescence immunoassay (ECLIA) methods in sheep. Blood samples were taken from the jugular vein of 25 clinically healthy, non-pregnant adult ewes. The plasma was analyzed to determine thyroxine (T₄), tri-iodothyronine (T₃), free thyroxine (fT₄) and free tri-iodothyronine (fT₃) concentrations. The data from this study indicates, there were significant differences in the T₄ (P < 0.0001), T₃(P < 0.01) and fT₃(P < 0.01) concentrations between the two methods, and the levels of these hormones were higher when using the ECLIA method. In determining thyroid hormones using the CLIA and ECLIA methods, significant positive correlations were found between T₄ and fT₄ (P < 0.001, r = 0.703; P < 0.0001, r = 0.806) also between T₃ and fT₃ (P < 0.0001, r = 0.922; P < 0.0001, r = 0.923) concentrations, respectively. The linear regression analysis of these hormones showed that the CLIA and ECLIA results were significantly correlated (T₄ (P < 0.01, r = 0.583), T₃ (P < 0.0001, r = 0.898), fT4 (P < 0.0001, r = 0.796) and fT₃ (P < 0.0001, r = 0.898).     

Relationship between plasma thyroid hormones and some biochemical parameters in Iranian Sarabi calves

The thyroid gland has some important endocrine hormones that regulate basal metabolism in various tissues of domestic animals. Thyroid hormones have a central role in animals’ development and their tissue functions. In this study, the relationship between the plasma thyroxine (T₄), triiodothyronine (T₃), free thyroxine (fT₄), free triiodothyronine (fT₃), triglyceride, cholesterol, glucose, total protein, and albumin concentrations as well as albumin/globulin ratio in different ages of Iranian Sarabi calves was investigated. Blood samples were collected from the jugular vein of 47 clinically healthy calves free from internal and external parasites (grouped according to their age—1–14 days, 1–2, and 3–6 months) in early of winter. The level of thyroid hormones was determined by chemiluminescence, and other parameters were measured by spectrophotometry using commercial kits. Our data from this study indicates that there was no significant difference and correlation in all the studied parameters between age groups and sexes. But we found a significant correlation between plasma T₄ and total protein (P < 0.05, r = 0.600), T₄ and albumin (P < 0.05, r = 0.575), T₃ and fT₃ (P < 0.05, r = 0.610), T₃ and total protein (P < 0.01, r = 0.725), T₃ and glucose (P < 0.01, r = 0.685), and fT₄ and fT₃ (P < 0.05, r = 0.609) concentrations as well as between total protein and albumin/globulin ratio (P < 0.01, r = −0.783).     

Changes in blood β-hydroxybutyrate and glucose concentrations during dry and lactation periods in Iranian Holstein cows

Clinical and subclinical ketoses are important metabolic diseases in dairy cattle during early lactation and are associated with losses in milk production and several other periparturient diseases. Limited information is available regarding the prevalence of clinical and subclinical ketoses in dairy herds in Iran. The objectives of this study were (1) to detect serum β-hydroxybutyrate (BHB) and glucose concentrations during pre- and postparturition periods, (2) to investigate the correlation between the blood concentrations of BHB and glucose pre- and postpartum, and (3) to establish a cutoff point of blood BHB concentration for detection of subclinical ketosis (SCK) in Iranian Holstein cow. In the present study, blood BHB and glucose concentrations of 13 Iranian Holstein cows (4–6 years old) from three commercial dairy herds were measured at 60, 30, and 7 days before and 30 and 60 days after calving. Cows had the highest concentration of BHB and the lowest concentration of glucose at 30 days postpartum period, which were significantly (p < 0.05) different from the prepartum period. High negative correlation coefficients (p < 0.05) were observed between serum BHB and glucose concentrations at 7 days prepartum (r = −0.84) and 30 days postpartum (r = −0.76) periods. The distribution of blood BHB concentrations seemed to suggest a cutoff point of 1,200 μmol/l to distinguish healthy cows from cows with SCK. At this cutoff point, 15.4% of cows had serum BHB concentration higher than the cutoff point of 1,200 μmol/l. The results of this study showed that the concentration of blood BHB during lactation is significantly higher than in the dry period, possibly due to higher energy demands of animals at this time, and the peak prevalence of SCK occurs in the first month after calving.     

Comparative study on the determination of serum thyroid hormones by two methods of immunoassay in broiler breeder poultry

Variations in blood thyroid hormone concentrations give an indirect indication of changes in thyroid gland activity; therefore, selecting a suitable method to determine these hormones is crucial. The aim of this study was to compare serum thyroid hormone concentrations (i.e. T₄, T₃, fT₄ and fT₃) using chemiluminescence immunoassay (CLIA) and enzyme-linked immunosorbent assay (ELISA) methods in broiler breeders. This study was carried out on 30 blood samples from randomly selected 45-week-old broiler breeders. Blood samples were collected in summer from the wing vein of birds by using disposable syringes. The separated serum was analysed to determine thyroxine (T₄), triiodothyronine (T₃), free thyroxine (fT₄) and free triiodothyronine (fT₃) concentrations using the mentioned methods. Data were processed in excel and statistical analysis was carried out using SPSS/ver17 software. Our data from this study indicates there was a significant difference in the T₄ (P < 0.0001), fT₄ (P < 0.01) and fT₃ (P < 0.05) concentrations between the two methods and that the levels of these hormones were higher when using the CLIA method, except for fT₃. The linear regression analysis of these hormones showed that the CLIA and ELISA results were significantly correlated only for fT₄ (P < 0.0001, r = 0.798) concentration. In conclusion, determination of the thyroid hormones using the CLIA method had an acceptable performance of higher sensitivity and precision and was more appropriate than the ELISA method for clinical application and investigation in poultry.     

Influence of sympatho-vagal balance on airway responsiveness in athletes

The increased prevalence of airway hyper-responsiveness (AHR) observed among athletes suggests that high-level training may contribute to the development of AHR. We investigated the possible influence of the sympatho-vagal balance on this phenomenon in 40 athletes and 10 sedentary controls. Each subject filled out a respiratory questionnaire, had a methacholine challenge, and measurements were made of their baseline plasma catecholamines [epinephrine (E), norepinephrine (NE) and dopamine (DA)] as a reflection of sympathetic tone, and their heart rate variability (SDNN: standard deviation of all normal-to-normal intervals) as an indicator of parasympathetic tone. The athletes had a 45% prevalence of AHR (defined as PC₂₀ < 16 mg/ml, where PC₂₀ is the concentration of methacholine inducing a 20% fall in the forced expiratory volume in 1 s, FEV₁) with a mean PC₂₀ of 21.2 mg/ml compared with 10% prevalence (mean PC₂₀: 74.4 mg/ml) in sedentary subjects (P < 0.01). Plasma catecholamine values were not significantly different between the two groups (all P > 0.05), but the estimated parasympathetic tone was higher in athletes (P=0.01). When data from all subjects were analyzed together, plasma E and NE correlated with PC₂₀ (r=0.39, P=0.005 and r=0.29, P < 0.005) but DA and SDNN did not (both P > 0.05). However, the ratios E/SDNN, NE/SDNN and DA/SDNN showed significant correlations with PC₂₀ (r=0.42, P < 0.01; r=0.33, P < 0.005 and r=0.31, P < 0.05, respectively). This study suggests that the sympatho-vagal balance may contribute to the increased AHR in the population studied but this influence alone cannot explain the higher prevalence of AHR in athletes. Accepted: 26 July 2000     

Relationship between the blood thyroid hormones and lipid profile in Moghani sheep; influence of age and sex

The aim of this study was to determine the correlation between thyroid hormones and lipid profile in blood of Iranian Moghani sheep in different ages and sexes. Blood samples were taken from the jugular vein of 260 clinically healthy and nonpregnant animals in eight age groups (1–14 days, 1–2, 2–3, 3–6, 6–12, 12–24, 24–48, and  > 48 months) in autumn. The plasma was analyzed to determine thyroxine (T₄), triiodothyronine (T₃), free thyroxine (fT₄), free triiodothyronine (fT₃), cholesterol, triglyceride, high-density lipoprotein (HDL-cholesterol), low-density lipoprotein (LDL-cholesterol) and very low-density lipoprotein (VLDL-cholesterol) concentrations. According to our data from Moghani sheep, an increase in age results in significant decreases in the plasma concentrations of T₄, T₃, fT₄, fT₃, cholesterol, and HDL-cholesterol (P < 0.05) but no gender-dependent significant differences in the studied parameters were found.     

Association between serum cortisol and progesterone concentrations and the infiltration of immune cells in the endometrium of gilts with vaginal discharge

The objective of the study was to investigate an association between serum cortisol and progesterone (P₄) concentrations and the distribution of immune cells in the endometrium of the gilts with vaginal discharge. Genital organs from 39 Landrace×Yorkshire crossbred gilts culled owing to vaginal discharge problem were collected from two commercial swine herds in Thailand. The estrous stage and gross pathology were examined. Blood samples were collected from the jugular vein prior to being slaughtered. Serum P₄ and cortisol were analyzed by means of enzyme immunoassay. The samples observed were in inactive (n = 4), follicular (n = 10), and luteal (n = 25) phases. They, afterwards, were processed in hematoxylin and eosin sections. The endometrium of the gilts was histologically divided into three layers, i.e., epithelial, subepithelial connective tissue, and glandular connective tissue layers. Immune cells, i.e., lymphocytes, neutrophils, eosinophils, macrophages, and plasma cells, in each layer were quantified under a light microscope (×400). The results revealed that mean serum cortisol was 430.6 ± 68.3 nmol/l. Serum P₄ varied by ovarian status. Serum P₄ of the gilts in the luteal phase was higher than those in the follicular phase (88.3 ± 7.7 versus 20.6 ± 6.2 nmol/l, P < 0.05). As for the endometrium condition, the gilts were classified into acute/subacute endometritis (n = 13), chronic endometritis (n = 9), and normal endometrium (n = 17). Neutrophils were the main local immune cells in the epithelial layer. Lymphocytes were the dominant population in the subepithelial and glandular connective tissue layers. Generally, the serum cortisol tended to negatively correlate with lymphocytes in the subepithelial connective tissue layer (r = −0.28, P = 0.081). In the gilts with acute/subacute endometritis, no correlation among serum cortisol, P₄, and immune cells was observed. In chronic endometritis gilts, only a negative correlation was remarked between P₄ and epithelial lymphocytes (r = −0.83, P = 0.010), epithelial neutrophils (r = −0.79, P = 0.019), and subepithelial neutrophils (r = −0.73, P = 0.025). In the gilts with normal endometrium, P₄ negatively correlated with subepithelial neutrophils (r = −0.55, P = 0.022) while positively correlated with subepithelial macrophages (r = 0.54, P = 0.024) and subepithelial eosinophils (r = 0.60, P = 0.011).     

Lipid and lipoprotein profiles, cardiovascular fitness, body composition, and diet during and after resistance, aerobic and combination training in young women

The purpose of this study was to evaluate the effects of various modes of training on the time-course of changes in lipoprotein-lipid profiles in the blood, cardiovascular fitness, and body composition after 16 weeks of training and 6 weeks of detraining in young women. A group of 48 sedentary but healthy women [mean age 20.4 (SD 1) years] were matched and randomly placed into a control group (CG, n=12), an aerobic training group (ATG, n=12), a resistance training group (RTG, n=12), or a cross-training group that combined both aerobic and resistance training (XTG, n=12). The ATG, RTG and XTG trained for 16 weeks and were monitored for changes in blood concentrations of lipoprotein-lipids, cardiovascular fitness, body composition, and dietary composition throughout a 16 week period of training and 6 weeks of detraining. The ATG significantly reduced blood concentrations of triglycerides (TRI) (P < 0.05) and significantly increased blood concentrations of high-density lipoprotein-cholesterol (HDL-C) after 16 weeks of training. The correlation between percentage fat and HDL-C was 0.63 (P < 0.05), which explained 40% of the variation in HDL-C, while the correlation between maximal oxygen uptake (V˙O_2max) and HDL-C was 0.48 (P < 0.05), which explained 23% of the variation in HDL-C. The ATG increased V˙O_2max by 25% (P < 0.001) and decreased percentage body fat by 13% (P < 0.05) after 16 weeks. Each of the alterations in the ATG had disappeared after the 6 week detraining period. The concentration of total cholesterol (TC), TRI, HDL-C and low density lipoprotein-cholesterol in the blood did not change during the study in RTG, XTG and CG. The RTG increased upper and lower body strength by 29% (P < 0.001) and 38%, respectively. The 6 week detraining strength values obtained in RTG were significantly greater than those obtained at baseline. The XTG increased upper and lower body strength by 19% (P < 0.01) and 25% (P < 0.001), respectively. The 6 week detraining strength values obtained in XTG were significantly greater than those obtained at baseline. The RTG, XTG and CG did not demonstrate any significant changes in either V˙O_2max, or body composition during the training and detraining periods. The results of this study suggest that aerobic-type exercise improves lipoprotein-lipid profiles, cardiorespiratory fitness and body composition in healthy, young women, while resistance training significantly improved upper and lower body strength only. Accepted: 9 April 2000     

Clinical features and treatment outcomes of vancomycin-intermediate <Emphasis Type="Italic">Staphylococcus aureus</Emphasis> (VISA) and heteroresistant vancomycin-intermediate <Emphasis Type="Italic">Staphylococcus aureus</Emphasis> (hVISA) in a tertiary care institution in Singapore

This retrospective case–control study was undertaken to review the clinical features associated with heteroresistant vancomycin-intermediate Staphylococcus aureus (hVISA) and vancomycin-intermediate S. aureus (VISA) infections and the local impact they have on clinical outcome. Compared with vancomycin-susceptible S. aureus (n = 30), hVISA and VISA infections (n = 10) are found to be associated with a longer period of prior glycopeptide use (P = 0.01), bone/joint (P < 0.01) and prosthetic infections (P = 0.04), as well as treatment failure, as evidenced by longer bacteremic (P < 0.01) and culture positivity (P < 0.01) periods. This was observed to have resulted in longer hospital length of stay (P < 0.01) and total antibiotic therapy duration (P = 0.01). There was, however, no significant difference in the overall patient mortality or the hospitalization cost (P = 0.12) in both groups. Clinicians should be cognizant of the association between hVISA/VISA with high bacterial load deep-seated infections. We recommend targeted and even universal screening for hVISA/VISA in methicillin-resistant S. aureus (MRSA) infections.     

Periparturient rise in fecal egg counts associated with prolactin concentration increase in French Alpine dairy goats

Previous data on periparturient relaxation of immunity during gastrointestinal nematode infection in goats are scarce and conflicting; one study carried out in fiber (Angora) goats showed a positive association of fecal egg counts with prolactin concentrations around parturition, whereas the two other available studies dealing with dairy goats, gave divergent results. The objectives of the study were thus to assess the occurrence of a periparturient rise in fecal egg counts in dairy goats and to examine a possible relationship between the level of milk production and the intensity of the periparturient rise. A total of 28 French Alpine grazing dairy goats naturally infected with Teladorsagia, Trichostrongylus, and Oesophagostomum were allocated into two groups according to their reproductive status; group 1 (n = 7) consisted of nonpregnant lactating animals in the 3^rd month of lactation, whereas group 2 (n = 21) was composed of dry goats at 6 weeks before term. Fecal egg counts, pepsinogen and phosphate blood concentrations, blood eosinophil counts, and prolactin concentrations were individually monitored at weekly intervals for 12 weeks (from midwinter to early spring). The mean fecal egg counts were significantly higher in pregnant goats during the 2 weeks before (668 versus 242 eggs per gram of feces (epg), P < 0.05) and the 2 weeks after (962 versus 279 epg, P < 0.01) parturition as compared with nonpregnant lactating animals. No significant difference was seen in the composition of larval cultures between the two groups of animals, with Oesophagostomum infective larvae being found predominantly, particularly at the time of parturition. Pepsinogen and phosphate concentrations as well as blood eosinophil counts were similar between the two groups throughout the survey and indicated a moderate larval challenge. The mean prolactin concentration measured in pregnant goats was significantly higher (P < 0.01) at the time of parturition (298 versus 130 ng ml⁻¹) and at 4 weeks after parturition (387 versus 193 ng ml⁻¹) than that determined in nonpregnant animals. Furthermore, a significant correlation (r _s = 0.30, df = 79; P < 0.01) between fecal egg counts and prolactin concentrations was recorded for the pregnant goats during the 4-weeks period around parturition. Received: 2 April 1998 / Accepted: 8 June 1998     

Relationship Between Eosinophilia and Levels of Chemokines (CCL5 and CCL11) and IL-5 in Bronchoalveolar Lavage Fluid of Patients With Mustard Gas-Induced Pulmonary Fibrosis

Objective Therefore, this study was designed to analyze the bronchoalveolar lavage (BAL) fluid concentrations of IL-5, RANTES (CCL5) and eotaxin (CCL11) and also to examine the relationship between the percentage and absolute number of the BAL eosinophils and these measured chemokines in patients with sulfur mustard (SM) gas-induced pulmonary fibrosis (PF). Patients Fifteen veterans with mustard gas-induced PF and 14 normal veterans as control group. Intervention Pulmonary function tests, tests for D_LCO, computed tomography scans of the chest, analyses of BAL fluids for RANTES (CCL5), eotaxin (CCL11), and IL-5 were performed in all cases. Results Eosinophilic alveolitis was the predominant feature (p < 0.0001). There were significant differences in CCL5, CCL11, and IL-5 levels of BAL fluid between patients with PF and controls (p < 0.0001, p < 0.0001, and p = 0.001, respectively). The concentrations of CCL5 and CCL11 showed positive correlations with percentage (r = 0.57 and p = 0.03; r = 0.52 and p = 0.04, respectively) and absolute counts (r = 0.54 and p = 0.04, r = 0.53 and p = 0.04, respectively) of BAL eosinophils. There were significant positive correlations between the concentrations of IL-5 and the proportion and total cell number of eosinophils in BAL (r = 0.67 and p = 0.01; r = 0.59 and p = 0.02, respectively) too. Conclusion A significant correlation between BAL CCL5, CCL11, and IL-5 levels and eosinophils in patients with pulmonary fibrosis due to SM gas inhalation has been demonstrated, suggesting that these C–C chemokines and IL-5 contribute to the recruitment of eosinophils cells in the lung in these victims.     

Peripheral and brachial blood pressure during standardized occupation-related tests in normotensive and mild hypertensive men and women

We investigated the usefulness of peripheral blood pressure (BP) measurement in the assessment of strain in occupational physiology. Our hypothesis was that the brachial and peripheral BP reflect physiologically different events under various occupation-related demands in normotensive (NT) and hypertensive (HT) people. A group of 20 female and 20 male subjects with unmedicated mild hypertension that had been diagnosed by ambulatory blood pressure monitoring [awake time systolic/diastolic BP (BP_s/BP_d) 142.9 (SD 11.3)/86.4 (SD 6.2) mmHg] and 40 NT matched by age and sex [BP_s/BP_d 120.0 (SD 9.8)/75.6 (SD 5.9) mmHg] attended a laboratory session to undertake mental arithmetic tasks, a fingergrip test and submaximal cycle ergometry. Brachial and peripheral BP as well as heart rate were measured using a sphygmomanometer and an continuously automatic blood pressure measuring device on the finger, respectively. The peripheral BP_s was higher than brachial BP_s, BP_d was similar for peripheral and brachial BP except during cycle ergometry. Associations between the levels of brachial and peripheral BP depended on demands and did not explain more than 42% of the common variance. The highest correlations between the two BP methods were observed during habituation, recovery and mental demands, and weak correlations during cycle ergometry. For peripheral BP_s and BP_d we found significant correlations in all phases of the test (r=0.58 to 0.86, P < 0.001), also in ergometry (NT r=0.62, P < 0.001, HT r=0.53, P < 0.001), in contrast to the brachial BP. Peripheral BP differentiated the two BP groups (57.5%–72.5% correctly classified) which had been grouped by daily measurement of brachial BP, but brachial BP was superior in this respect with 65.0%–87.5% being correctly classified. These results supported the suggestion that the combined measurement of peripheral and brachial BP provides complementary information regarding physiological changes in NT and HT in different situations. Accepted: 30 August 1999     

Effects of glucose ingestion at the onset of moderate-intensity, prolonged exercise in women as compared to men

To test glucose tolerance during exercise, the effects of oral glucose ingestion (0.5 g · kg⁻¹) on plasma glucose and hormonal responses (insulin, catecholamines) were investigated in 11 women [mean (SEM) age 21.6 (1.3) years] and 10 men [22.0 (0.3) years] during cycle ergometer exercise (30 min at 60% maximum oxygen consumption, V˙O_2max). The two groups exhibited similar V˙O_2max values, when expressed per kg of lean body mass. Venous blood samples (5 ml) were withdrawn immediately before the exercise, during the exercise (at 3, 5, 10, 15 and 30 min) and at the 30th min of the recovery period. Glucose was ingested orally between the 2nd and the 3rd min of the exercise. As compared to men, plasma glucose concentrations were lower in women during exercise (P < 0.05 at 3, 15 and 30 min) and at the 30th min of the recovery period (P < 0.001), while plasma insulin concentrations were higher in women during exercise (P < 0.05 at 3, 15 and 30 min). The ratio of the area under the curve for glucose over the area under the curve for insulin was lower in women during exercise (P < 0.0002). A linear relationship between glucose and insulin concentrations was found only for women during exercise (r = 0.615, P < 0.0001). No gender difference was observed for the catecholamine concentration during exercise. In conclusion, this study postulates that an oral glucose load given at the onset of a prolonged and moderate exercise bout induced lesser plasma glucose and greater insulin concentrations in women as compared to men. These data argue in favour of a greater glucose tolerance in women during exercise. Accepted: 5 June 1999     

Benefit of endurance training in elderly people over a short period is reversible

 The present study assessed daily activity, physical capacity and body composition in 11 initially sedentary healthy subjects [5 men and 6 women, mean age 62.8 (SD 2.7) years] before training (T_o), after completion of 7 (T_7w) and 14 (T_14w) weeks of training, and again 6 (T_6m) and 12 (T_12m) months after training. The mean daily activity index decreased from T_7w to T_12m reaching a lower level than at T_o [T_12m − T_o = −1.5 (SD 4.6) units, P = 0.18]. Mean maximal oxygen uptake (V˙O_2max) and its corresponding mean power output (W˙ _max) were increased by 12.5 (SD 6.6)% (P = 0.003) and 22.8 (SD 12.8)% (P = 0.003), respectively, at T_14w, and returned to their T_o levels within 1 year. Mean body mass (m _b) remained stable until T_6m but increased significantly by 2.6 (SD 3.7)% from T_6m to T_12m (P < 0.05). Mean fat mass (m _f, from bioelectrical impedance analysis measurements) tended to decrease [−2.0 (SD 4.2)%, P = 0.10] during the training period but increased by 7.8 (SD 10.9)% between T_6m and T_12m (P < 0.05). The mean fat free mass did not vary during the study period (P = 0.81) but magnetic resonance imaging (MRI) showed that mean thigh muscle volume decreased between T_7w and T_12m to less than at T_o [T_12m − T_o = −2.3 (SD 3.6)%, P = 0.05]. Therefore, this study confirmed the favourable effects of endurance training on the physical capacity and body composition of elderly people, but demonstrated that the training programme would have to be continued to maintain the training-related benefits (i.e. increased V˙O_2max and W˙ _max) which would otherwise be lost within 1 year. After training, m _b and m _f were found to be increased. Furthermore, a fast and reproducible MRI protocol was validated for study of small intra-individual variations in tissue volumes in longitudinal studies. Accepted: 7 September 1999     

Influence of ultra-long-term fatigue on the oxygen cost of two types of locomotion

The aim of this study was to examine the effects of fatigue induced by a 65-km ultramarathon on the oxygen cost of running (C_r) and cycling (C_cycl). The day before and immediately after the race, a group of nine well-trained male subjects performed two sub-maximal 4-min exercise bouts: one cycling at a power corresponding to 1.5 W · kg⁻¹ body mass on an electromagnetically braked ergometer, and one running at 11 km · h⁻¹ on a flat asphalt roadway. Before oxygen cost determinations, the subjects performed 12 “ankle” jumps at a given frequency that was fixed by an electronic metronome (2.5 Hz). From the non-fatigued to the fatigued condition, there was a significant increase in minute ventilation for both running (P < 0.01) and cycling (P < 0.0001). Significant changes were also found in respiratory exchange ratio both for running (P=0.01) and cycling (P < 0.0001). However, running and cycling differed in that C_cycl increased significantly by [mean (SD)] 24.2 (11.5)% (P < 0.001), suggesting an alteration of muscle efficiency, while C_r did not change with fatigue [186.8 (14.1) mlO₂ · kg⁻¹ · km⁻¹ vs 186.8 (18.7) mlO₂ · kg⁻¹ · km⁻¹]. In addition, contact times during hopping increased significantly from 0.173 (0.019) ms to 0.194 (0.027) ms (P < 0.01). Analysis of the factors that determine C_r indicate that the subjects modified their movement pattern in order to decrease the mechanical cost of running in such long-term fatigue conditions. Accepted: 7 August 2000     

Relevance of individual characteristics for thermoregulation during exercise in a hot-dry environment

The aim of this study was to investigate the relevance of individual characteristics for thermoregulation during prolonged cycling in the heat. For this purpose, 28 subjects cycled for 60 min at 60% VO_2peak in a hot-dry environment (36 ± 1°C; 25 ± 2% relative humidity, airflow 2.5 m/s). Subjects had a wide range of body mass (99–43 kg), body surface area (2.2–1.4 m²), body fatness (28–5%) and aerobic fitness level (VO_2peak = 5.0–2.1 L/min). At rest and during exercise, rectal and mean skin temperatures were measured to calculate the increase in body temperature (ΔT _body) during the trial. Net metabolic heat production (M _NET) and potential heat loss (by means of evaporation, radiation and convection) were calculated. Although subjects exercised at the same relative intensity, ΔT _body presented high between-subjects variability (range from 0.44 to 1.65°C). ΔT _body correlated negatively with body mass (r = −0.49; P < 0.01), body surface area (r = −0.47; P < 0.01) and T_body at rest (r = −0.37; P < 0.05), but it did not significantly correlate with body fatness (r = 0.12; P > 0.05). ΔT _body positively correlated with the body surface area/mass ratio (r = 0.46; P < 0.01) and the difference between M _NET and potential heat loss (r = 0.56; P < 0.01). In conclusion, a large body size (mass and body surface area) is beneficial to reduce ΔT _body during cycling exercise in the heat. However, subjects with higher absolute heat production (more aerobically fit) accumulate more heat because heat production may exceed potential heat loss (uncompensability).     

Neuromuscular adaptation during prolonged strength training, detraining and re-strength-training in middle-aged and elderly people

Effects of a 24-week strength training performed twice weekly (24 ST) (combined with explosive exercises) followed by either a 3-week detraining (3 DT) and a 21-week re-strength-training (21 RST) (experiment A) or by a 24-week detraining (24 DT) (experiment B) on neural activation of the agonist and antagonist leg extensors, muscle cross-sectional area (CSA) of the quadriceps femoris, maximal isometric and one repetition maximum (1-RM) strength and jumping (J) and walking (W) performances were examined. A group of middle-aged (M, 37–44 years, n=12) and elderly (E, 62–77, n=10) and another group of M (35–45, n=7) and E (63–78, n=7) served as subjects. In experiment A, the 1-RM increased substantially during 24 ST in M (27%, P < 0.001) and E (29%, P < 0.001) and in experiment B in M (29%, P < 0.001) and E (23%, P < 0.01). During 21 RST the 1-RM was increased by 5% at week 48 (P < 0.01) in M and 3% at week 41 in E (n.s., but P < 0.05 at week 34). In experiment A the integrated electromyogram (IEMG) of the vastus muscles in the 1-RM increased during 24 ST in both M (P < 0.05) and E (P < 0.001) and during 21 RST in M for the right (P < 0.05) and in E for both legs (P < 0.05). The biceps femoris co-activation during the 1-RM leg extension decreased during the first 8-week training in M (from 29 ± 5% to 25 ± 3%, n.s.) and especially in E (from 41 ± 11% to 32 ± 9%, P < 0.05). The CSA increased by 7% in M (P < 0.05) and by 7% in E (P < 0.001), and by 7% (n.s.) in M and by 3% in E (n.s.) during 24 ST periods. Increases of 18% (P < 0.001) and 12% (P < 0.05) in M and 22% (P < 0.001) and 26% (P < 0.05) in E occurred in J. W speed increased (P < 0.05) in both age groups. The only decrease during 3 DT was in maximal isometric force in M by 6% (P < 0.05) and by 4% (n.s.) in E. During 24 DT the CSA decreased in both age groups (P < 0.01), the 1-RM decreased by 6% (P < 0.05) in M and by 4% (P < 0.05) in E and isometric force by 12% (P < 0.001) in M and by 9% (P < 0.05) in E, respectively, while J and W remained unaltered. The strength gains were accompanied by increased maximal voluntary neural activation of the agonists in both age groups with reduced antagonist co-activation in the elderly during the initial training phases. Neural adaptation seemed to play a greater role than muscle hypertrophy. Short-term detraining led to only minor changes, while prolonged detraining resulted in muscle atrophy and decreased voluntary strength, but explosive jumping and walking actions in both age groups appeared to remain elevated for quite a long time by compensatory types of physical activities when performed on a regular basis. Accepted: 2 May 2000     

The effects of drafting on stroking variations during swimming in elite male triathletes

The aim of this study was to determine the effects of drafting behind another swimmer on the metabolic response and stroke characteristics. Six highly trained male triathletes performed two maximal 400-m swims, one in a drafting (D) and one in a non-drafting condition (ND). Their metabolic response was assessed by measuring the oxygen uptake (V˙O₂) and the blood lactate concentration at the end of each 400 m. Swimming velocity, stroke frequency, stroke length, and stroke index (velocity multiplied by stroke length) were recorded every 50 m. In the D and ND conditions, there was no difference in V˙O₂ [66.7 (1.7) ml · kg⁻¹ · min⁻¹ vs 65.6 (1.2) ml · kg⁻¹ · min⁻¹, respectively], however, the lactate concentrations were lower in D than in ND [9.6 (0.9) mM vs 10.8 (0.9) mM, respectively, P < 0.01]. In D, the performance [1.39 (0.02) m · s⁻¹ vs 1.34 (0.02) m · s⁻¹, respectively, P < 0.01] and the stroking parameters (i.e., stroke length and stroke index) increased significantly, while the stroke frequency remain unchanged. In D, a stable pace was maintained, while in ND, velocity decreased significantly throughout the 400 m. In D, the performance gains were related to the 400-m D velocity (r=0.78, P < 0.05), and to the body fat mass (BFM, r=0.99, P < 0.01). The stroke index in D was also related to BFM (r=0.78, P < 0.05). Faster and leaner swimmers achieved greater performance gains and stroke index when drafting. Thus, drafting during swimming increases the performance and contributes to the maintenance of stable stroking parameters such as stroke frequency and stroke length during a 400-m swim. Accepted: 10 April 2000     

Dose dependency of prednisolone tertiary-butylacetate (PTBA) treatment on the establishment and site predilection of Echinococcus multilocularis in an alternative definitive host model using Mongolian gerbil (Meriones unguiculatus)

Mongolian gerbils (Meriones unguiculatus) were orally inoculated with 10,000 protoscoleces of Echinococcus multilocularis per head after being divided into five groups (A–E). Each group was dosed with prednisolone tertiary-butylacetate (PTBA) as follows: A, 0 mg; B, 0.5 mg; C, 2 mg; D, 5 mg; and E, 10 mg/head. All animals were injected subcutaneously with control solvent or PTBA every other day from 6 days pre- to 6 days post-infection. Autopsy was performed at 7 days post-infection. Doses of PTBA and the number of worms recovered showed a positive correlation (r=0.929, P < 0.0001). In groups A, B and C, the predilection site of the worms in the small intestine could not be determined, while in group D the worms were found more in the anterior part. In group E, the predilection site was the anterior part, followed by the middle and the posterior parts of the small intestine (Fisher's test: P < 0.01). The number of worms recovered from the anterior and the middle part of the small intestine also correlated positively with PTBA dose (anterior part: r=0.930, P < 0.0001, middle part: r=0.917, P < 0.0001). All groups of the PTBA-treated animals showed significant loss of weight compared to the non-treated animals (P < 0.01). Received: 26 September 1999 / Accepted: 24 November 1999     

Subacute Inflammatory Activation in Subjects with Acute Coronary Syndrome and Left Ventricular Dysfunction

Several lines of evidence indicate that increased inflammatory cytokine levels can be used for risk prediction in patients with acute coronary syndrome (ACS). This study therefore aimed to evaluate correlations between levels of soluble interleukin (IL)-2 receptor (sIL-2r), IL-6, and IL-8 and in-hospital incidence of acute heart failure (AHF) and left ventricular (LV) systolic dysfunction in the subacute phase of ACS. In 48 consecutive patients with ACS, circulating levels of sIL-2r, IL-6, and IL-8 were ascertained 72–96 h after onset of symptoms. Clinical data, LV function, and in-hospital incidence of AHF were also evaluated. IL-8 levels were significantly higher in patients with pulmonary edema (1,829 ± 2,496 vs 456 ± 624 pg/ml, p < 0.05); sIL-2r, IL-6, and IL-8 levels were increased proportionally to Killip class (r = 0.35, p < 0.05; r = 0.48, r = 0.47, p < 0.01) and in patients with LV ejection fraction (LVEF) < 30%. Levels of sIL-2r were inversely related to LVEF in subjects with acute myocardial infarction (r = −0.51, p < 0.05). Soluble IL-2r and IL-8 levels were related to mitral regurgitation severity (r = 0.34, p < 0.05; r = 0.37, p < 0.05). Levels of sIL-2 were proportional to LV end-diastolic diameter (r = 0.49, p < 0.001) and LV end-systolic diameter (r = 0.58, p < 0.001). Number of cytokines with circulating values above upper level of normal was significantly correlated with Killip class and LVEF (r = 0.40, r = −0.38, p < 0.05). sIL-2r, IL-6, and IL-8 are increased in patients with ACS and systolic dysfunction or AHF. These data suggest that inflammatory cytokine activity detectable in peripheral blood may be useful in identifying subjects with a worse clinical course.