Slavec Zvonka Zapanic: New Method of Identifying Family Related Skulls, In: Forensic Medicine, Anthropology, Epigenetics, mit Vorworten von Gertrude Hauser, Eugen Strouhal, Igor Grdina, Springer, Wien, New York, ISBN 3-211-22044-5, 2004 (255 Seiten, 101 Abbildungen, EUR 69.- Hardcover).

Пpoвoдилocь oпpeдeлeниe oбшeй хyвcтвитeльнocти caмoк мышeй C 57/BL/6J в вoзpacтe oт 4 дo 24 мecяцeв к yкopaхивaюшeмy жизнь дeйcтвию 1400 R, пpи oблyхeнии 10 paвными дpoбнымqi хacтями, пpихeм cpaвнивaлиcь 5 гипoтeз, кoтopыe пытaютcя oбъяcнить cнижeниe хyвcтвитeльнocти измeнeниeм в вepoятнoй пpoдoлжитeльнocти жизни co cтapeниeм. Coкpaшeния вepoятнoй пpoдoлжитeльнocти жизни paвнялиcь 148 дням y мышeй в вoзpacтe 120 днeй, нo oни paвнялиcь 30-днeвнoмy coкpaшeнию пpи oблхeнии в вoзpacтe 9 мecяцeв. Tpи нaибoлee cтapыe гpyппы (450, 540 и 730 днeй), пoдвepгнyтыe иccлeдoвaнaиию, oбнapyжили нoминaльныe пoвышeния вepoятнoй пpoдoлжитeqlьнocти жизни, paвныe 53–65 дням. Эти нaблюдeния нe мoгyт быть oбъяcнeны нeдocтaтoхным вpeмeнeм для выявлeния пoвpeждeния, тoждecтвoм cтapeния и лyхeвoгo пopaжeния, или жe ceлeктивными cдвигaми в пoпyляюии, oбycлoвлeнными cильным cмepтeльным эффeктoм излyхeния или нopмaльным изнocoм. Bepoятнee вceгo, хтo cтapeниe cнижaeт хyвcтвитeльнocть к внeдpeнию нeкoтopых бoлeзнeй, нeзaвиcимo oт “вpeмeни, нeoбхoдoимoгo для выpaжeния”, пpихeм вoзмoжнo, хтo paдиoaктивнoe oблyeниe дaжe oкaзывaeт извecтй тepaпeвтихecкий зффeкт нa cтapых бoльных живoтных.

Metabolite selection for machine learning in childhood brain tumour classification

MRS can provide high accuracy in the diagnosis of childhood brain tumours when combined with machine learning. A feature selection method such as principal component analysis is commonly used to reduce the dimensionality of metabolite profiles prior to classification. However, an alternative approach of identifying the optimal set of metabolites has not been fully evaluated, possibly due to the challenges of defining this for a multi-class problem. This study aims to investigate metabolite selection from in vivo MRS for childhood brain tumour classification. Multi-site 1.5 T and 3 T cohorts of patients with a brain tumour and histological diagnosis of ependymoma, medulloblastoma and pilocytic astrocytoma were retrospectively evaluated. Dimensionality reduction was undertaken by selecting metabolite concentrations through multi-class receiver operating characteristics and compared with principal component analysis. Classification accuracy was determined through leave-one-out and k-fold cross-validation. Metabolites identified as crucial in tumour classification include myo-inositol (P < 0.05, $\text{◂,▸}\text{AUC}=0.81\pm 0.01$), total lipids and macromolecules at 0.9 ppm (P < 0.05, $\text{◂,▸}\text{AUC}=0.78\pm 0.01$) and total creatine (P < 0.05, $\text{◂,▸}\text{AUC}=0.77\pm 0.01$) for the 1.5 T cohort, and glycine (P < 0.05, $\text{◂,▸}\text{AUC}=0.79\pm 0.01$), total N-acetylaspartate (P < 0.05, $\text{◂,▸}\text{AUC}=0.79\pm 0.01$) and total choline (P < 0.05, $\text{◂,▸}\text{AUC}=0.75\pm 0.01$) for the 3 T cohort. Compared with the principal components, the selected metabolites were able to provide significantly improved discrimination between the tumours through most classifiers (P < 0.05). The highest balanced classification accuracy determined through leave-one-out cross-validation was 85% for 1.5 T ¹H-MRS through support vector machine and 75% for 3 T ¹H-MRS through linear discriminant analysis after oversampling the minority. The study suggests that a group of crucial metabolites helps to achieve better discrimination between childhood brain tumours.     

Der Feinbau des Oogenotop bei Cestoden

Zusammenfassung Die Stätte der Eibildung (Oogenotop, GöNNERT 1962) wird für mehrere Spczies der Klasse der Cestoden beschrieben.Der Oogenotop der Cestoden umfaßt die zuleitenden Genitalwcge (Oviduct, Vagina, Receptaculum seminis, Vitelloduct und Ovo-Vitelloduct), den Ootyp mit Mehlisscher Drüse und die ableitenden Genitalwege (Uteringang und Uterus), sowie X-Zellen, die wahrscheinlich Neuronen darstellen und zur Steuerung der Funktionen bei der Eibildung notwendig sind.Die Mehlissche Drüse besteht aus zwei Zellarten: 1. seröse Drüsenzellen in der Nähe des Ootyp, 2. muköse Drüsenzellen im peripheren Bereich der Drüse. Die Einmündungszone der beiden Drüsentypen ist bei den einzelnen Spezies unterschiedlich. Für beide Drüsentypen wird die Anordnung der Zellelemcnte und der Funktionsrhythmus beschrieben.Die artspezifischen Sonderbildungen werden gesondert aufgeführt.Verzeichnis der in den Abbildungen gebrauchten Abkürzungen B Basalmembran - Bk Befruchtungskanal - C Cuticula - Do Dotterzelle - Ds Dotterstock - Dz Drüsenzelle - E Embryo - Ef Ergastoplasma - Ei Ei - Em Embryophore - Epz Epithelzelle - Ez Ernährungszelle - Flz Flimmerzelle - Gl Grundlamelle - K Zellkern - L Lumen - M Mensur - Mb Myoblast - Md muköse Drüsenzelle(n) - Mf Muskelfaser - Mz Muskelzelle - Nl Nucleolus - O Ovar - Oc Ovicapt - Od Oviduct - Oo Ootyp - Oos Ootypschaltstück - Ovd Ovo-Vitelloduct - Or Oocytenreservoir - Oy Oocyte - Oy ₁ Zygote - R Reservesulbstanz - Rs Receptaculum seminis - S Sekret - Sd seröse Drüsenzelle - Sf Sekretionsfortsatz - Sk Sklerotinschale - Sp Spermien - Spt Spermioduct - Ss Schalensubstanz - Uk Uterinkapsel - Ut Uterus - Ug Uteringang - Vc Vitellocapt - Vd Vitelloduct - Vds Vitelloductschaltstück - Vres Dotterzellenreservoir - Vg Vagina - X X-Zelle - Zw Zellwand Verzeichnis der Abkürzungen von Namen der untersuchten Spezies Amp Amphiptyches urna - Avi Avitellina centripunctata - Bot Bothridium pithonis - Car Caryophyllaeus laticeps - Dav Davainea proglottina - Dil Dipylidium caninum - Dip Diphyllobothrium latum - Ech Echeneibothrium maculatum - Egr Echinococcus granulosus - Emu Echinococcus multilocularis - Eut Eutetrarhynchus ruficollis - Hym Hymenolepis diminuta - Hyd Hydatigera taeniaeformis - Ich Ichthyotaenia percae - Kha Khawia iowensis - Mon Moniezia expansa - Nem Nematotaenia dispar - Pro Progamotaenia zschokkei - Sti Stilesia hepatica - Tae Taenia pisiformis - Tri Triaenophorus nodulosus Mit 22 Textabbildungen     

Influences of a dietary supplement in combination with an exercise and diet regimen on adipocytokines and adiposity in women who are overweight

The influence of a proprietary blend of modified cellulose and cetylated fatty acids (Trisynex™, Imagenetix, Inc., San Diego, CA 92127, USA) on adipocytokine and regional body composition responses to a weight loss program was examined. Twenty-two women (Supplement group (S) (n = 11): age = 36.8 ± 7.2 years; weight = 87.1 ± 6.2 kg; % body fat = 43.4 ± 4.1; Placebo group (P) (n = 11): age = 38.3 ± 6.8 years; weight = 86.9 ± 4.7 kg; % body fat = 44.3 ± 2.0) completed an 8-week placebo-controlled, double-blind study consisting of a caloric restricted diet and cardiovascular exercise. Body composition and serum insulin, leptin, and adiponectin were assessed at pre-, mid-, and post-intervention. From pre- to post-intervention, significant decreases (P < 0.05) were observed for body weight (S: 87.1 ± 6.2–77.9 ± 5.1 kg; P: 86.9 ± 4.7–82.7 ± 3.8 kg) (P < 0.05 S vs. P), % body fat (S: 43.4 ± 4.1–36.1 ± 3.6; P: 44.3 ± 2.0–40.6 ± 1.2) (P < 0.05 S vs. P), leptin (S: 28.3 ± 3.5–16.2 ± 2.6 ng ml⁻¹; P: 29.4 ± 3.2–19.9 ± 1.1 ng ml⁻¹) (P < 0.05 S vs. P), and insulin (S: 7.3 ± 0.8–5.1 ± 0.2 mU l⁻¹; P: 7.7 ± 0.9–5.1 ± 0.3 mU l⁻¹). Serum adiponectin increased (P < 0.05) (S: 12.2 ± 2.4–26.3 ± 3.0 μg ml⁻¹: 12.6 ± 2.0–21.8 ± 3.1 μg ml⁻¹) (P < 0.05 for S vs. P). Supplementation with a proprietary blend of modified cellulose and cetylated fatty acids during an 8-week weight loss program exhibited favorable effects on adipocytokines and regional body composition.     

Exercise intensity and oxygen uptake kinetics in African-American and Caucasian women

The effect of exercise intensity on the on- and off-transient kinetics of oxygen uptake (VO₂) was investigated in African American (AA) and Caucasian (C) women. African American (n = 7) and Caucasian (n = 6) women of similar age, body mass index and weight, performed an incremental test and bouts of square-wave exercise at moderate, heavy and very heavy intensities on a cycle ergometer. Gas exchange threshold (LT_GE) was lower in AA (13.6 ± 2.3 mL kg⁻¹ min⁻¹) than C (18.6 ± 5.6 mL kg⁻¹ min⁻¹). The dynamic exercise and recovery VO₂ responses were characterized by mathematical models. There were no significant differences in (1) peak oxygen uptake (VO_2peak) between AA (28.5 ± 5 mL kg⁻¹ min⁻¹) and C (31.1 ± 6.6 mL kg⁻¹ min⁻¹) and (2) VO₂ kinetics at any exercise intensity. At moderate exercise, the on- and off- VO₂ kinetics was described by a monoexponential function with similar time constants τ _1,on (39.4 ± 12.5; 38.8 ± 15 s) and τ _1,off (52.7 ± 10.1; 40.7 ± 4.4 s) for AA and C, respectively. At heavy and very heavy exercise, the VO₂ kinetics was described by a double-exponential function. The parameter values for heavy and very heavy exercise in the AA group were, respectively: τ _1,on (47.0 ± 10.8; 44.3 ± 10 s), τ _2,on (289 ± 63; 219 ± 90 s), τ _1,off (45.9 ± 6.2; 50.7 ± 10 s), τ _2,off (259 ± 120; 243 ± 93 s) while in the C group were, respectively: τ _1,on (41 ± 12; 43.2 ± 15 s); τ _{2, on} (277 ± 81; 215 ± 36 s), τ _1,off (40.2 ± 3.4; 42.3 ± 7.2 s), τ _2,off (215 ± 133; 228 ± 64 s). The on- and off-transients were symmetrical with respect to model order and dependent on exercise intensity regardless of race. Despite similar VO₂ kinetics, LT_GE and gain of the VO₂ on-kinetics at moderate intensity were lower in AA than C. However, generalization to the African American and Caucasian populations is constrained by the small subject numbers.     

Blood gases and cardiovascular shunt in the South American lungfish (Lepidosiren paradoxa) during normoxia and hyperoxia

The South American lungfish (Lepidosiren paradoxa  ) has an arterial P_O2${\text{P}}_{{\text{O}}_2}$ (Pa_O2$\text{P}{\text{a}}_{{\text{O}}_2}$) as high as 70–100 mm Hg, corresponding to Hb–O₂ saturations from 90% to 95%, which indicates a moderate cardiovascular right to left (R–L) shunt. In hyperoxia (50% O₂), we studied animals in: (1) aerated water combined with aerial hyperoxia, which increased Pa_O2$\text{P}{\text{a}}_{{\text{O}}_2}$ from 78 ± 2 to 114 ± 3 mm Hg and (2) and aquatic hyperoxia (50% O₂) combined room air, which gradually increased Pa_O2$\text{P}{\text{a}}_{{\text{O}}_2}$ from 75 ± 4 mm Hg to as much as 146 ± 10 mm Hg. Further, the hyperoxia (50%) depressed pulmonary ventilation from 58 ± 13 to 5.5 ± 3.0 mL BTPS kg h⁻¹, and Pa_CO2$\text{P}{\text{a}}_{\text{C}{\text{O}}_2}$ increased from 20 ± 2 to 31 ± 4 mm Hg, while pHa became reduced from 7.56 ± 0.03 to 7.31 ± 0.09. At the same time, venous P_O2${\text{P}}_{{\text{O}}_2}$ (Pv_O2$\text{P}{\text{v}}_{{\text{O}}_2}$) rose from 40.0 ± 2.3 to 46.4 ± 1.2 mm Hg and, concomitantly, Pv_CO2$\text{P}{\text{v}}_{\text{C}{\text{O}}_2}$ increased from 23.2 ± 1.1 to 32.2 ± 0.5 mm Hg. R–L shunts were estimated to about 19%, which is moderate when compared to most amphibians.     

Cardiac function and arteriovenous oxygen difference during exercise in obese adults

The purpose of this study was to assess cardiac function and arteriovenous oxygen difference (a-vO₂ difference) at rest and during exercise in young, normal-weight (n = 20), and obese (n = 12) men and women who were matched for age and fitness level. Participants were assessed for body composition, peak oxygen consumption (VO_2peak), and cardiac variables (thoracic bioimpedance)—cardiac index (CI), cardiac output (Q), stroke volume (SV), heart rate (HR), and ejection fraction (EF)—at rest and during cycling exercise at 65% of VO_2peak. Differences between groups were assessed with multivariate ANOVA and mixed-model ANOVA with repeated measures controlling for sex. Absolute VO_2peak and VO_2peak relative to fat-free mass (FFM) were similar between normal-weight and obese groups (Mean ± SEE 2.7 ± 0.2 vs. 3.3 ± 0.3 l min⁻¹, p = 0.084 and 52.4 ± 1.5 vs. 50.9 ± 2.3 ml kg FFM⁻¹ min⁻¹, p = 0.583, respectively). In the obese group, resting Q and SV were higher (6.7 ± 0.4 vs. 4.9 ± 0.1 l min⁻¹, p < 0.001 and 86.8 ± 4.3 vs. 65.8 ± 1.9 ml min⁻¹, p < 0.001, respectively) and EF lower (56.4 ± 2.2 vs. 65.5 ± 2.2%, p = 0.003, respectively) when compared with the normal-weight group. During submaximal exercise, the obese group demonstrated higher mean CI (8.8 ± 0.3 vs. 7.7 ± 0.2 l min⁻¹ m⁻², p = 0.007, respectively), Q (19.2 ± 0.9 vs. 13.1 ± 0.3 l min⁻¹, p < 0.001, respectively), and SV (123.0 ± 5.6 vs. 88.9 ± 4.1 ml min⁻¹, p < 0.001, respectively) and a lower a-vO₂ difference (10.4 ± 1.0 vs. 14.0 ± 0.7 ml l00 ml⁻¹, p = 0.002, respectively) compared with controls. Our study suggests that the ability to extract oxygen during exercise may be impaired in obese individuals.     

The identification of a VH subgroup allotypic specificity,y30, which differentiates the y33 allele into two variants. Implications for rabbit VH gene organization and evolution

A new anti-allotype Ab,^∥ designated anti-y30, was produced by immunizing rabbits of the VH genotype a²x³²y³³/a²x³²y³³ with purified IgG from $\text{a}{}^1\text{x}{}^{\mathrm{?}}\text{y}{}^{33}\text{a}{}^1\text{x}{}^{\mathrm{?}}\text{y}{}^{33}$ rabbits suppressed for al Ig synthesis. Genetic analysis of 200 rabbits representing 12 heavy chain (VH-CH) haplotypes indicated that y30 was controlled by the heavy chain chromosomal region and was expressed in rabbits of the VH haplotype a¹x^?y³³ but not of theVH haplotypes a¹x^?y^?, a²x³²y³³ or a³x³²y^?. Thus, some rabbits express y33 with y30 whereas others express y33 without y30. By immunodiffusion, radioimmunoassay and sequential precipitation techniques, y30 and y33 were found to be co-expressed on most of the IgG molecules from $\text{a}{}^1\text{x}{}^{\mathrm{?}}\text{y}{}^{33}\text{a}{}^1\text{x}{}^{\mathrm{?}}\text{y}{}^{33}$ rabbits suppressed for the al allotype. Also, when newborn $\text{a}{}^1\text{x}{}^{\mathrm{?}}\text{y}{}^{\mathrm{?}}\text{a}{}^1\text{x}{}^{\mathrm{?}}\text{y}{}^{33}$ rabbits were injected at birth with either anti-y33 or anti-y30 Ab, both allotypic specificities were initially suppressed and subsequently escaped suppression in unison. From this, we suggest that two variants of the y³³ allele exist, y^33,30 and y³³,?; an inhibition of radioprecipitation assay indicated that the y33 specificity was qualitatively similar in both variants. These allelic variants, presumably representing differences in amino acid sequence, may hve resulted from an ancestral recombinational event within a VH Cistron prior to gene duplication and expansion into present day VH subgroups. The highly restricted association observed between genetic markers of the a,x, and y VH subgroups argues against recombination between the VH subgroups.     

Describing individual variation in local sweating during exercise in a temperate environment

It has been previously demonstrated that the individual variation in whole-body sweat rate is described by differences in each participant’s heat balance status. It was hypothesized that the individual variation in local sweat rate of the forehead (LSR_head) and forearm (LSR_arm) would be similarly described using a whole-body heat balance approach, specifically the ratio of evaporation required for heat balance relative to the maximum evaporation possible (i.e. E _req:E _max). Twelve males cycled at 60% [(V)\dot]\textO _{2 \textmax} \dot{V}{\text{O}}_{{ 2 {\text{max}}}} for 60 min at 24.9 ± 0.5°C, 31 ± 14% relative humidity. Rectal (T _re) and aural canal (T _au) temperatures as well as mean skin temperature ( [`(T)]<sub>\textsk</sub> \bar{T}_{\text{sk}} ), metabolic energy expenditure (M) and rate of external work (W) were measured throughout. In addition, whole-body sweat rate at steady state (WBSR<sub>ss</sub>) was estimated using the change in body mass over the last 15 min of exercise, with LSR<sub>head</sub> and LSR<sub>arm</sub> estimated using technical absorbent patches applied between the 50th and 55th minute. WBSR<sub>ss</sub> significantly correlated with M–W (r = 0.66, P = 0.021), E <sub>req</sub> (r = 0.69, P = 0.013) and E <sub>req</sub>:E <sub>max</sub> (r = 0.87, P < 0.001); LSR<sub>head</sub> was significantly correlated with E <sub>req</sub>:E <sub>max</sub> (r = 0.82, P = 0.001), but not M–W (r = 0.31, P = 0.328) or E <sub>req</sub> (r = 0.38, P = 0.227); and LSR<sub>arm</sub> significantly correlated with E <sub>req</sub> (r = 0.62, P = 0.031) and E <sub>req</sub>:E <sub>max</sub> (r = 0.78, P = 0.003) but not M–W (r = 0.56, P = 0.059). None of WBSR<sub>ss</sub>, LSR<sub>head</sub> or LSR<sub>arm</sub> significantly correlated with any variations in T <sub>re</sub>, T <sub>au</sub> or [`(T)]_\textb \bar{T}_{\text{b}} (i.e. 0.8T _re + 0.2 [`(T)]_\textsk \bar{T}_{\text{sk}} ). Secondary analyses also demonstrated that both LSR_head (r = 0.79, P = 0.002) and LSR_arm (r = 0.89, P < 0.001) correlated with WBSR_ss. In conclusion, the individual variation in WBSR_ss, LSR_head and LSR_arm is described by the ratio of E _req relative to E _max.     

Opening–closing pattern of four pericardial prostheses: results from an in vitro study of leaflet kinematics

Pericardial and porcine stented aortic valves have different leaflet kinematics. To study the biomechanics of a prosthesis thoroughly, the in vitro setting is the most appropriate. The aim of our study was to find out whether the prosthesis design in which the pericardial sheet is outside the stent post might influence the opening and closing patterns of the leaflets. Four pericardial prostheses (Magna Ease [MG] 21, Trifecta [TRI] 21, Soprano-Armonia [SA] 20 and Mitroflow [MF] 23) that fitted aortic roots with a native annulus diameter of 2.1 cm were implanted and their leaflet kinematics was studied by a high-speed digital camera. In the opening phase, MG showed the shortest RVOT and the highest RVOVI, with values of 12 ± 2 and 209 ± 17 ms, respectively. The RVOT of MG was significantly shorter than that of MF (p < 0.01), but not than that of TRI (p = 0.286). Both TRI and SA showed similar opening patterns (TRI: RVOT of 15 ± 3 ms and RVOVI of 132 ± 25 ms; SA: 17 ± 2 ms and 126 ± 19 ms), without statistically significant difference. Conversely, MF showed the slowest profile, with an RVOT of 23 ± 3 ms and an RVOVI of 94 ± 8 ms (Table 1; Fig. 3). The opening/closing profile is not influenced by the position of the pericardial leaflets, but depends on other intrinsic structural characteristics related to the material used for the stent and leaflets. Moreover, the kinematics does not affect the valve performance.

Table 1 Kinematics and hydrodynamic results, reported as means and standard deviations, evaluated over the tested heart samples

	TRI	SA	MG	MF	ANOVA	TRI versus SA	TRI versus MG	TRI versus MF	SA versus MG	SA versus MF	MG versus MF
					p Value	p Value	p Value	p Value	p Value	p Value	p Value
ET (ms)						1.0	1.0	1.0	1.0
RVOT (ms)	15 ± 3	17 ± 2	12 ± 2	23 ± 3	<0.01	1.0	0.286	<0.01	0.03	<0.01	<0.01
SVCT (ms)	247 ± 14	231 ± 15	256 ± 26	241 ± 11	0.170	0.463	0.853	0.931	0.213	1.0	1.0
RVCT (ms)	35 ± 19	52 ± 13	32 ± 17	52 ± 4	0.07	0.474	1.0	0.494	0.236	1.0	0.247
TVCT (ms)	283 ± 10	283 ± 19	289 ± 10	293 ± 11	0.584	1.00	1.0	1.0	1.0	1.0	1.0
RVOVI (ms?1)	132 ± 25	126 ± 19	209 ± 17	94 ± 8	<0.01	0.959	<0.01	0.02	<0.01	0.07	<0.01
SVCVI (ms?1)	?0.9 ± 0.3	?1.1 ± 0.4	?0.57 ± 0.1	?0.55 ± 0.1	<0.01	1.0	0.353	0.292	0.045	0.04	1.0
RVCVI (ms?1)	?16 ± 4	?10 ± 2	?18 ± 6	?10 ± 1	<0.01	0.396	1.0	0.513	0.025	1.0	0.03
Δp (mmHg)	6.7 ± 3.6	10.6 ± 5.5	15.2 ± 7.9	10.7 ± 6.1	<0.01	0.01	<0.01	0.01	0.04	1.0	<0.01
EOA (cm2)	2.2 ± 1.2	1.7 ± 0.9	1.5 ± 0.8	1.7 ± 0.9	<0.01	0.03	<0.01	0.01	0.261	0.617	0.11
El  %	7.3 ± 1	11.9 ± 1	15.4 ± 2	11.8 ± 3	<0.01	<0.01	<0.01	<0.01	0.04	1.00	0.03
CO (L/min)	3.1 ± 0.4	2.8 ± 0.5	3.1 ± 0.3	3.0 ± 0.5	0.534	0.282	0.792	0.702	0.106	0.552	0.559

ET ejection time, RVOT rapid valve-opening time, SVCT slow valve-closing time, RVCT rapid valve-closing time, TVCT total valve-closing time, RVOVI rapid valve-opening velocity index, SVCVI slow valve-closing velocity index, RVCVI rapid valve-closing velocity index, Δp mean pressure drop, EOA effective orifice area, El % energy loss, CO cardiac output

     

Réponse adrénergique à l'exercice musculaire intense chez le sujet sédentaire en fonction de l'emotivité et de l'entrainement

Résumé Sept sujets masculins sédentaires ont effectué sur une bicyclette ergométrique des exercices musculaires intenses (80% de la consommation maximale d'oxygène), soit d'une courte durée (15 min), soit pendant le temps nécessaire pour atteindre l'épuisement (durée moyenne égale à 47±2 min).Les catécholamines plasmatiques ont été dosées par une méthode originale avant le début de l'exercice et pendant la dernière minute de course. L'adrénaline et la noradrénaline sont, dans ce protocole, extraites séparément du plasma et dosées chacune dans des éluats distincts par une méthode fluorimétrique de haute sensibilité. Cette technique permet de déceler des concentrations aussi faibles que 15 ng par litre de plasma.Il apparaÎt une différence de réponse très importante selon l'émotivité des sujets, révélée par la prédominance de la sécrétion d'adrénaline au repos et à l'exercice (rapport NA/A<1).Chez les sujets non émotifs (rapport NA/A>1 au repos), l'adrénalinémie et la noradrénalinémie augmentent proportionnellement à la durée de l'exercice. Les variations de noradrénalinémie sont plus élevées que celles d'adrénalinémie; cependant, les taux d'adrénaline sont corrélés à ceux de noradrénaline, ce qui suggère une stimulation parallèle et coordonnée des glandes médullo-surrénales et du système nerveux orthosympathique.Chez les sujets émotifs (rapport NA/A<1 au repos), l'appréhension de l'épreuve provoque la dissociation des réponses adrénalinique et noradrénalinique: alors que la libération de noradrénaline ne semble pas altérée par l'anxiété du sujet, la sécrétion d'adrénaline s'élève déjà avant l'épreuve et devient massive au début de celle-ci, puis reste sensiblement constante jusqu'à l'épuisement.L'entraÎnement (deux exercices intenses par semaine pendant deux mois) s'accompagne chez les non émotifs d'une réduction très marquée de la libération de noradrénaline pendant l'exercice épuisant. Dans les mÊmes conditions, la réponse médullo-surrénalienne n'est pas significativement modifiée.Ces résultats montrent que la réponse adrénergique varie en fonction de l'intensité de l'épreuve et paraÎt très adaptée aux besoins de l'organisme pendant celle-ci; ceci suggère que les catécholamines jouent un rÔle très important chez l'homme dans la régulation de l'homéostasie lors de l'exercice intense. Cependant, à cette sécrétion spécifique ajustée, se superpose, chez les sujets émotifs, une stimulation médullo-surrénalienne très intense qui semble essentiellement d'origine psychologique.E.R.A. 330, CNRS, Exercice musculaire     

Selection des travailleurs en ambiance chaude

Résumé Chez 57 sujets les résultats d'épreuves d'ergospirométrie en ambiance normale sont comparés à ceux de cinq épreuves effectuées en chantier à température élevée. On n'observe aucune relation significative entre l'aptitude physique en ambiance normale mesurée par la consommation maximum d'O₂, le régime stable limite selon Petit et coll. ou la V_{O 2}/170 et la tolérance à la chaleur estimée en chantier. Un exercise effectué à température ordinaire ne suffit donc pas pour prédire la tolérance à un effort à haute température; il peut cependant servir à une présélection.Les critères de sélection sont ensuite recherchés en étudiant les réactions physiologiques lors d'épreuves d'ergospirométrie en ambiance chaude. Cette dernière consiste en un exercice d'intensité modérée (11 O₂/mn), d'une durée prolongée pendant 1/2 h, dans une ambiance très chaude (t _s 46 °C;t _h 35 °C). Dans ces conditions, la température centrale n'est pas toujours représentative de la contrainte thermique et la fréquence cardiaque paraît constituer un critère préférable parce que plus sélectif et plus limitatif.La valeur absolue de la fréquence cardiaque fournit un témoin synthétique de la contrainte globale entraînée conjointement par le travail musculaire et l'ambiance chaude. L'adaptation à ces deux sollicitations cardio-vasculaires n'est pas nécessairement parallèle et pour chaque individu on peut en préciser les modalités. La fréquence cardiaque mesurée pendant un exercice physique en ambiance normale précise les possibilités circulatoires musculaires. L'évolution du pouls en fonction de rhyperthermie apprécie la tolérance à la contrainte thermique.     

Blood HbO<Subscript>2</Subscript> and HbCO<Subscript>2</Subscript> Dissociation Curves at Varied O<Subscript>2</Subscript>, CO<Subscript>2</Subscript>, pH, 2,3-DPG and Temperature Levels

New mathematical model equations for O₂ and CO₂ saturations of hemoglobin (S_HbO2 and S_HbCO2) are developed here from the equilibrium binding of O₂ and CO₂ with hemoglobin inside RBCs. They are in the form of an invertible Hill-type equation with the apparent Hill coefficients _KHbO2 and K_HbCO2 in the expressions for S_HbO2 and S_HbCO2 dependent on the levels of O₂ and CO₂ partial pressures (P_O2 and P_CO2), pH, 2,3-DPG concentration, and temperature in blood. The invertibility of these new equations allows P_O2 and P_CO2 to be computed efficiently from S_HbO2 and S_HbCO2 and vice-versa. The oxyhemoglobin (HbO₂) and carbamino-hemoglobin (HbCO₂) dissociation curves computed from these equations are in good agreement with the published experimental and theoretical curves in the literature. The model solutions describe that, at standard physiological conditions, the hemoglobin is about 97.2% saturated by O₂ and the amino group of hemoglobin is about 13.1% saturated by CO₂. The O₂ and CO₂ content in whole blood are also calculated here from the gas solubilities, hematocrits, and the new formulas for S_HbO2 and S_HbCO2. Because of the mathematical simplicity and invertibility, these new formulas can be conveniently used in the modeling of simultaneous transport and exchange of O₂ and CO₂ in the alveoli-blood and blood-tissue exchange systems.     

Non-invasive haemodynamic assessments using Innocor™ during standard graded exercise tests

Cardiac output (Q) and stroke volume (V _S) represent primary determinants of cardiovascular performance and should therefore be determined for performance diagnostics purposes. Since it is unknown, whether measurements of Q and V _S can be performed by means of Innocor™ during standard graded exercise tests (GXTs), and whether current GXT stages are sufficiently long for the measurements to take place, we determined Q and V _S at an early and late point in time on submaximal 2 min GXT stages. 16 male cyclists (age 25.4 ± 2.9 years, body mass 71.2 ± 5.0 kg) performed three GXTs and we determined Q and V _S after 46 and 103 s at 69, 77, and 85% peak power. We found that the rebreathings could easily be incorporated into the GXTs and that Q and V _S remained unchanged between the two points in time on the same GXT stage (69% peak power, Q: 18.1 ± 2.1 vs. 18.2 ± 2.3 l min⁻¹, V _S: 126 ± 18 vs. 123 ± 21 ml; 77% peak power, Q: 20.7 ± 2.6 vs. 21.0 ± 2.3 l min⁻¹, V _S: 132 ± 18 vs. 131 ± 18 ml; 85% peak power, Q: 21.6 ± 2.4 vs. 21.8 ± 2.7 l min⁻¹, V _S: 131 ± 17 vs. 131 ± 22 ml). We conclude that Innocor™ may be a useful device for assessing Q and V _S during GXTs, and that the adaptation of Q and V _S to exercise-to-exercise transitions at moderate to high submaximal power outputs is fast enough for 1 and 2 min GXT stage durations.     

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).     

Effects of athletes’ muscle mass on urinary markers of hydration status

To determine if athletes’ muscle mass affects the usefulness of urine specific gravity (U _sg) as a hydration index. Nine rugby players and nine endurance runners differing in the amount of muscle mass (42 ± 6 vs. 32 ± 3 kg, respectively; P = 0.0002) were recruited. At waking during six consecutive days, urine was collected for U _sg analysis, urine osmolality (U _osm), electrolytes ( \mathop U\nolimits_{[\textNa ⁺ ]} {\mathop U\nolimits_{[{\text{Na}}^{ + } ]} }, \mathop U\nolimits_{[\textK ⁺ ]} {\mathop U\nolimits_{[{\text{K}}^{ + } ]} } and \mathop U\nolimits_{[\textCl ^- ]} {\mathop U\nolimits_{[{\text{Cl}}^{ - } ]} }) and protein metabolites (U _[Creatinine], U _[Urea] and U _{[Uric acid]}) concentrations. In addition, fasting blood serum osmolality (S _osm) was measured on the sixth day. As averaged during 6 days, U _sg (1.021 ± 0.002 vs. 1.016 ± 0.001), U _osm (702 ± 56 vs. 554 ± 41 mOsmol kg⁻¹ H₂O), U _[Urea] (405 ± 36 vs. 302 ± 23 mmol L⁻¹) and U _{[Uric acid]} (2.7 ± 0.3 vs. 1.7 ± 0.2 mmol L⁻¹) were higher in rugby players than runners (P < 0.05). However, urine electrolyte concentrations were not different between groups. A higher percentage of rugby players than runners (56 vs. 11%; P = 0.03) could be cataloged as hypohydrated by U _sg (i.e., >1.020) despite S _osm being below 290 mOsmol kg⁻¹ H₂O in all participants. A positive correlation was found between muscle mass and urine protein metabolites (r = 0.47; P = 0.04) and between urine protein metabolites and U _sg (r = 0.92; P < 0.0001). In summary, U _sg specificity to detect hypohydration was reduced in athletes with large muscle mass. Our data suggest that athletes with large muscle mass (i.e., rugby players) are prone to be incorrectly classified as hypohydrated based on U _sg.     

The effect of 48?weeks of aerobic exercise training on cutaneous vasodilator function in post-menopausal females

Skin blood flow (SkBF) and endothelial-dependent vasodilatation decline with ageing and can be reversed with exercise training. We tested whether 48 weeks of training could improve SkBF and endothelial function in post-menopausal females; 20 post-menopausal subjects completed the study. SkBF was measured by laser-Doppler flowmetry (LDF). Cutaneous vascular conductance (CVC) was calculated as LDF/blood pressure. Resting CVC was measured at 32°C and peak CVC at 42°C. Cutaneous endothelial-dependent and -independent vasodilatations were determined by the iontophoresis of acetylcholine (ACh) and sodium nitroprusside (SNP), respectively. All assessments described were performed at entry (week 0), and after 6, 12, 24, 36, and 48 weeks of training. Resting CVC measures did not change (P > 0.05) throughout the study. Peak CVC increased (P < 0.05) after 24 weeks (7.2 ± 1.2 vs. 11.6 ± 1.4 AU mmHg⁻¹) and at the 36- and 48-week assessments (13.0 ± 1.7 and 14.9 ± 2.1 AU mmHg⁻¹, respectively). Responses to ACh also increased (P < 0.05) at the 24-week assessment (5.1 ± 2.1 vs. 8.55 ± 2.3 AU mmHg⁻¹) and increased further at the 36 and 48-week assessments (11.6 ± 3.7 and 13.2 ± 3.9 AU mmHg⁻¹, respectively). Cutaneous responses to SNP increased (P < 0.05) after 36 weeks (8.7 ± 2.1 vs. 13.02 ± 2.23 AU mmHg⁻¹ at 36 weeks). VO_2max increased after 12 weeks (23.5 ± 0.7 vs. 25.4 ± 0.9 ml kg⁻¹ min⁻¹) and improved (P < 0.05) further throughout the study (31.6 ± 1.8 ml kg⁻¹ min⁻¹ at week 48). Aerobic exercise produces positive adaptations in the cutaneous vasodilator function to local heating as well as in cutaneous endothelial and endothelial-independent vasodilator mechanisms. Aerobic capacity was also significantly improved. These adaptations were further enhanced with progressive increases in exercise intensity.