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PubMed2002

Hormone-dependent fluctuations of pressure pain threshold and tactile threshold of the temporalis and masseter muscle.

In order to better objectify reported pain and disturbed sensation, psychophysical parameters as pressure pain threshold (PPT) and tactile threshold (TT) have been introduced in pain research. The present study evaluated fluctuations of these parameters, obtained using an algometer (PPT) and von Frey hairs (TT), in relation to fluctuations in female reproductive hormones. Ten students not using oral contraceptives and eight students using oral contraceptives participated in the study. In addition, seven male students served as a control group. During two menstrual cycles, the PPT and TT of the masseter and temporalis muscles, as well as from the hand, were obtained twice per week. At the end of the study the values were evaluated in relation to the different phases of the menstrual cycle, by means of a linear mixed model. The TT appeared very reproducible within subjects and did not fluctuate over time. Scores on the left temporalis muscle appeared significantly higher than that on the right side. In all subjects the PPT tended to be higher on the left side, while in students using oral contraceptives, the PPT values of the temporalis muscle were significantly higher in the menstrual phase, and lower in the follicular phase. A significant correlation between the PPT of the temporalis muscle and the TT of the overlying skin was observed.

Adult↗
PubMed2003

Blood lactate disappearance dynamics in boys and men following exercise of similar and dissimilar peak-lactate concentrations.

Characteristically, children recover faster than adults from various types of exercise. The purpose of the present study was to explain the children's faster recovery, in part, by addressing lactate (La) removal and comparing La disappearance dynamics in the two age groups following exercise of both similar and dissimilar peak blood-lactate concentration values ([La]pk). The subjects were 14 prepubertal boys and 12 men of similar peak oxygen consumption, normalized for body mass. All subjects performed 30 s supra-maximal cycling (Wingate anaerobic test [WAnT]). [La]pk was 10.7 +/- 1.9 and 14.7 +/- 1.7 mmol x l(-1) for the boys and men, respectively (p < 0.001). The men were later retested in shortened versions of the WAnT so as to attain [La]pk values (10.5 +/- 0.7 mmol x l(-1)) comparable to those achieved by the boys. [La]pk lag time following the boys' standard WAnT was similar to that found in the men following the shortened WAnT (5.0 +/- 2.6 vs 5.7 +/- 1.3 min, respectively), but considerably shorter than that following the men's 30s-WAnT (7.6 +/- 2.1 min; p < 0.05). The La disappearance dynamics were closely matched between groups following the matched [La]pk WAnTs. [La] half-life was similar under all conditions (ca. 20 min). It is concluded that prepubertal boys are characterized by a lower [La]pk and a shorter time lag before reaching it, following 30-s supra-maximal cycling exercise. However, boys' La disappearance dynamics are not different from that of men.

Adolescent↗
PubMed2002

Estrogen receptor alpha expression in normal human breast epithelium is consistent over time.

If increased expression of estrogen receptor alpha (ER) in benign breast epithelium increases susceptibility to breast cancer, such overexpression should be stable over time. There are no published data regarding this important aspect of ER expression in breast epithelium. We examined the temporal consistency of ER expression in the normal breast tissue of 28 women who had 2 separate breast surgical procedures, at least 6 months apart (mean interval, 2.8 years). Paraffin embedded breast tissue blocks containing an adequate sample of normal breast epithelium and no cancer, were sectioned and processed using the 6F11 antibody and standard immunohistochemical techniques. The ER labelling index (ER LI) was calculated by counting a mean of 2,000 epithelial cells. The median ER LI at first sampling was 13.6 and at second sample 15.5, with R(2) = 0.34 and p = 0.001. The ER LI was categorized into high and low values, using a threshold of 10. Twenty-four women (85.7%) showed concordance of high and low expression between the 2 samples (p = 0.002). There were 11 women who were premenopausal at both time points. Among them, much of the variation in ER LI was explained by differences in the menstrual cycle day at the time of sampling and adding the day of cycle to the regression model substantially improved the correlation between first and second labeling indices. These data suggest that ER expression of normal breast tissue is fairly consistent over time and support the notion that overexpression of ER in normal epithelium is a constant feature of the high risk breast.

Adult↗
PubMedDate not supplied

Identification and characterization of the sulfate precipitate in GI147211C IV formulation.

GI147211, a water soluble analog of camptothecin, is currently being investigated for the treatment of cancer as a topoisomerase I inhibitor. Precipitate was observed in some samples of a stability lot of the IV clinical formulation after being stored at 5 degrees C for one month. The precipitate was identified as the sulfate salt of GI147211 by various techniques including Environmental Scanning Electron Microscope/Energy Dispersive X-ray (ESEM/EDX) and Ion Chromatography (IC). The cause of the precipitation was proven to be from the presence of residual sulfate ions in ammonium sulfate treated glass vials that were suspected to be improperly washed. The solubility product (Ksp) of the sulfate salt was determined in 5% dextrose solution adjusted to pH 3.5 at 5 degrees C to mimic the clinical formulation and refrigerated storage conditions. The Ksp was also determined at 15 and 33 degrees C to determine the temperature effect on the constant. The stoichiometry of the sulfate salt was determined by solubility experiments using HPLC and IC to be 2:1 (base/salt). Based on the stoichiometry, the Ksp was calculated to be 3.04 x 10(-12), 9.27 x 10(-12) and 9.96 x 10(-11) M3 at 5 degrees C, 15 degrees C and 33 degrees C, respectively. Using the Ksp values, the sulfate threshold in GI147211 Injection when GI147211 sulfate precipitates was determined to be 1.3, 3.8 and 41 ppm at 5, 15 and 33 degrees C, respectively. Further experiments demonstrated that using the proper cleaning techniques the sulfate level in the treated vials was reduced to < 1.3 ppm. The washing cycles for the vials used for clinical supplies were thereafter modified so that the sulfate precipitate would no longer be an issue.

Antineoplastic Agents↗
PubMed1989

Longitudinal assessment of responses by triathletes to swimming, cycling, and running.

Fourteen triathletes (eight male, six female) were tested four times (in February, May, August, and October) to monitor adaptations to training for a triathlon (1.9-km swim, 90.3-km bike, 21.1-km run). VO2max was measured during treadmill running (TR), cycle ergometry (CE), and tethered swimming (TS). Lactate threshold (LT), defined as the VO2 at a lactate concentration of 4 mM, was determined during TR and CE. In all sessions, TS VO2max was less than TR and CE (P less than 0.05), and CE was less than TR (P less than 0.05). Means for Session I were 57.4, 53.4, and 48.3 ml.min-1.kg-1 for TR, CE, and TS, respectively. Corresponding values for Session IV were 58.4, 56.0, and 47.8 ml.min-1.kg-1. The only significant increase in VO2max was for CE (5%). VO2 at the LT increased from Session I to IV for both TR (6%) and CE (10%); the LT for TR was at a higher VO2 than for CE in all sessions. The percent VO2max at LT for TR in Sessions I and IV was 80 and 85%, respectively. Analogous values for CE were 72 and 76%. The minimal increases in VO2max suggest that subjects had reached their potential in this parameter. Improvements in race performance were probably attained through peripheral adaptations, as suggested by increases in the VO2 at LT. The occurrence of the LT at a lower percent VO2max in cycling than in running suggests that the triathletes had greater potential for improvement in cycling.

Adult↗
PubMed1987

Exercise performance and ventilatory response in the menstrual cycle.

We investigated the effects of the luteal phase of the menstrual cycle, as compared with the follicular phase, on ventilatory response (VR) and exercise performance in eight normally menstruating, non-athletic women. Subjects were studied near the predicted mid-point of each phase which was later documented by serum progesterone level. Resting VR to hypercapnia was greater, and VR to hypoxia tended to be greater in the luteal phase than in the follicular phase, but the increases in VRs were unrelated to progesterone level. There were no differences in maximal oxygen uptake, maximal duration of exercise, maximal heart rate, work efficiency, maximal ventilation (VE), anaerobic (ventilatory) threshold, gas exchange, cardiac output, or oxygen delivery. The PaCO2 was lower, and pHa tended to be higher during exercise. VE per unit CO2 output (VE/VCO2) was increased. R values (VCO2/VO2) were less, and maximal lactate values tended to be less, suggestive of increased dependence on fat for energy metabolism. At a given workload, exercise VE was unchanged due to the effect of less CO2 output at a given VO2 (lower R), balancing increased VE/VCO2. We conclude that, although ventilatory parameters are altered by the menstrual cycle, there is no overall effect on maximal exercise performance.

Adult↗
PubMed2005

Method to predict isthmus location in ventricular tachycardia caused by reentry with a double-loop pattern.

BACKGROUND: During electrophysiologic study, induction and mapping of clinical reentrant ventricular tachycardia can be difficult. Hence, analysis of sinus-rhythm electrograms for reentry localization is of potential clinical relevance. Herein is described a method of sinus-rhythm electrogram shape analysis, that does not require arbitrary threshold values, for localization of double-loop reentrant circuits that drive clinical tachycardias. METHODS AND RESULTS: Reentrant ventricular tachycardia was induced by premature stimulation in 23 postinfarction canine hearts 4-5 days after left anterior descending (LAD) ligation. Sinus-rhythm activation maps were constructed from bipolar electrograms acquired at 196-312 sites in the epicardial border zone. The timing of all electrogram peak deflections during one cycle of sinus rhythm was determined, and the mean (MPD) and deviation (DPD) were taken, respectively, as estimates of the time of activation wavefront crossing, and the duration of local electrical activity. These variables were then mapped on a computerized grid. The line of most uniform and sharp MPD gradient predicted the propagation direction through the double-loop reentrant circuit isthmus that would occur upon tachycardia induction. The sharpest transitions in DPD bounding this line predicted the positions of arcs of block that would border the reentrant circuit isthmus during tachycardia. The actual and estimated isthmuses overlapped by a mean of 84.1 +/- 3.8%. In six experiments lacking inducible reentrant tachycardia, no line of sharp MPD gradient was present in the MPD maps. CONCLUSIONS: Analysis of multiple sinus-rhythm deflections can localize the reentrant ventricular tachycardia isthmus without introduction of arbitrary threshold points and peak choices that may lead to error.

Algorithms↗
PubMed1992

Differential mobilization of leucocyte and lymphocyte subpopulations into the circulation during endurance exercise.

A total of 14 healthy subjects [means (SD): 27.6 (3.8) years; body mass 77.8 (6.6) kg; height 183 (6) cm] performed endurance exercise to exhaustion at 100% of the individual anaerobic threshold (Th(an)) on a cycle ergometer (mean workload 207 (55) W; lactate concentrations 3.4 (1.2) mmol.l-1; duration 83.8 (22.2) min, including 5 min at 50% of individual Th(an)). Leucocyte subpopulations were measured by flow cytometry and catecholamines by radioimmunological methods. Blood samples were taken before and several times during exercise. Values were corrected for plasma volume changes and analysed using ANOVA for repeated measures. During the first 10 min of exercise, of all cell subpopulations the natural killer cells (CD3-CD16/CD56+) increased the most (229%). Also CD3+CD16/CD56+ (84%), CD8+CD45RO- (69%) cells, eosinophils (36%) and monocytes (62%) increased rapidly during that time. CD3+, CD3+HLA-DR+, CD4+CD45RO+, CD4+CD45RO-, CD8+CD45RO+ and CD19+ cells either did not increase or increased only slightly during exercise. Adrenaline and noradrenaline increased nearly linearly by 36% and 77% respectively at 10 min exercise. The increase of natural killer cells and heart rates between rest and 10 min of exercise correlated significantly (r = 0.576, P = 0.031). We conclude that natural killer cells, cytotoxic, non-MHC-restricted T-cells, monocytes and eosinophils are mobilized rapidly during the first minutes of endurance exercise. Both catecholamines and increased blood flow are likely to contribute this effect.

Adult↗
PubMed2002

Mobilization and oxidative burst of neutrophils are influenced by carbohydrate supplementation during prolonged cycling in humans.

Prolonged, strenuous exercise may lead to suppressive effects on the immune system, which might be responsible for a greater susceptibility to opportunistic infections. The aim of this study was to examine the influence of carbohydrate substitution (CHS) during prolonged, strenuous exercise on neutrophil granulocytes and their oxidative burst (intracellular oxidation of dihydrorhodamine(123) to rhodamine(123) after induction by formylized 1-methionyl-1-leucyl-1-phenylalanin) using flow cytometry. In three trials different concentrations of CHS (placebo compared to 6% and 12% CHS; 50 ml.kg(-1)) were given randomly to 14 endurance trained cyclists [mean (SD) age 25 (5) years, maximal oxygen uptake 67 (6) ml.min(-1).kg(-1)] cycling for 4 h in a steady state at 70% of their individual anaerobic threshold. Blood samples were taken before, immediately after cessation, 1 h and 19 h after exercise. A significant rise in neutrophil counts was observed immediately after cessation and 1 h after exercise with a return to normal rest values 19 h after exercise for all three conditions ( P<0.001). The relative proportions of rhodamine(123)+ neutrophils were significantly diminished in all three conditions 1 h after exercise ( P<0.01), while the mean fluorescence intensity was lowest in the placebo trial and differed significantly to the 12% CHS trial ( P=0.024) and almost significantly to the 6% CHS trial ( P=0.052). In conclusion, these data suggest a beneficial effect of CHS on the neutrophil oxidative burst and a possible attenuation of the susceptibility to infections, presumably due to the reduction of metabolic stress in prolonged, strenuous exercise.

Adult↗
PubMed1994

Three-dimensional echocardiography for quantitative left ventricular wall motion analysis: a method for reconstruction of endocardial surface and evaluation of regional dysfunction.

A method for quantitative LV wall motion analysis based on 3-D reconstruction of the LV endocardial surface is presented. The reconstruction is based on a minimum of three transthoracic apical 2-D cineloops of the LV, digitally transferred from the ultrasound scanner to a computer. Images are obtained by rotating the transducer around the LV long axis. Endocardial borders are traced with an automatic edge detection algorithm with manual correction. These borders are used with a specially designed computer algorithm for reconstruction of LV cavity 3-D shape, and LV volumes, ejection fraction, and endocardial surface area can be determined. The end-diastolic and end-systolic endocardial surfaces are compared for analysis of regional wall motion. A threshold value is selected to discriminate between normal and abnormal wall motion. Regional wall motion abnormalities are displayed in a bull's eye plot, and the corresponding endocardial surface area is expressed in percent of the total endocardial area. Phase analysis is performed from reconstruction of the endocardial surface throughout the cardiac cycle, and displays regions with abnormal wall motion as being out of phase with LV volume variation. Thus, LV 3-D reconstruction performed by this method can be used for quantitative analysis of wall motion in several clinical situations, and due to the simplicity of processing the data, can be useful outside the research laboratory.

Echocardiography↗
PubMed2004

Thyroid status and endothelium-dependent vasodilation in skeletal muscle.

Cardiovascular dysfunction is characteristic of both hypo- and hyperthyroidism. Endothelium-dependent dilation of conductance vessels is impaired in hypothyroidism but augmented in hyperthyroidism. We hypothesized that these alterations in dilation extend into the resistance vasculature of skeletal muscle. To test this hypothesis, rats were made hypothyroid with propylthiouracil (Hypo; n = 13) or hyperthyroid with triiodothyronine (Hyper; n = 9) over 3-4 mo. Compared with euthyroid controls (Eut; n = 14), Hypo rats were characterized by reduced skeletal muscle oxidative capacity and blunted growth; Hyper rats exhibited increased muscle oxidative capacity and left ventricular hypertrophy (P < 0.05 for all effects). Vasodilation to the endothelium-dependent agent acetylcholine ( approximately 2 x 10(-4) M) in skeletal muscle was determined in situ. Conductance in certain muscles increased from control [e.g., soleus: 0.98 +/- 0.15 (Eut), 0.79 +/- 0.14 (Hypo), and 1.06 +/- 0.24 ml.min(-1).100 g(-1).mmHg(-1) (Hyper); not significant among groups] to acetylcholine [1.91 +/- 0.21 (Eut), 2.28 +/- 0.26 (Hypo), and 2.15 +/- 0.33 ml.min(-1).100 g(-1).mmHg(-1) (Hyper); P < 0.05 vs. control values for all groups] but did not differ among groups. Expression of mRNA for the endothelial isoform of nitric oxide synthase in resistance vessels isolated from various muscles was similarly unchanged with alterations in thyroid status [e.g., soleus 1A arterioles: 33.15 +/- 0.58 (Eut), 32.73 +/- 0.27 (Hypo), and 32.80 +/- 0.54 (Hyper) cycles at threshold; not significant]. These data suggest that endothelium-dependent dilation of resistance vasculature in skeletal muscle is unchanged in both hypo- and hyperthyroidism. These data also emphasize the importance of examining resistance vasculature to improve understanding of effects of chronic disease on integrated cardiovascular function.

Acetylcholine↗
PubMed2001

Diurnal variations of post-exercise parasympathetic nervous reactivation in different chronotypes.

The purpose of this study was to investigate the diurnal variation and chronotype differences, i.e., in morning-types and evening-types, in post-exercise vagal reactivation. Twelve healthy male college students who were classified as morning-type (6) and evening-type (6), based on responses to a questionnaire, participated in this study. Postexercise vagal reactivation was assessed as the time constant of the beat-by-beat heart rate decrease for the first 30 sec after exercise (T30) at an intensity lower than the ventilatory threshold. The subjects performed 3-min cycle ergometer exercise at an intensity corresponding to 80% of the ventilatory threshold after a 1 min warm-up exercise in the morning (7:00 - 8:00) and evening (17:00 - 18:00) to obtain the T30. A significant interaction (chronotype-by-time) effect was found for T30. The morning value of the T30 in evening-type subjects was significantly larger than their evening value and the morning value in morning-type subjects. There was no significant interaction effect for heart rate and oxygen uptake during exercise. These results suggest that diurnal variation in post-exercise vagal reactivation is different between morning-type and evening-type, and post-exercise vagal reactivation in evening-type individuals is sluggish in the morning.

Adult↗
PubMed2002

Endometrial volume and thickness measurements predict pituitary suppression and non-suppression during IVF.

BACKGROUND: The aim of this prospective study was to evaluate the usefulness of three-dimensional (3D) ultrasound measurement of endometrial volume and thickness as a predictor of pituitary suppression and non-suppression following GnRH agonist administration for IVF. METHODS: A total of 144 women undergoing 164 IVF cycles had transvaginal ultrasound measurement of their endometrial volume and thickness following 8-14 days of buserelin acetate administration. Serum estradiol concentrations were measured on the same day. Receiver operating characteristic (ROC) curve analysis was used for statistics. A ROC curve was produced for each of four estradiol thresholds commonly used by clinics to diagnose pituitary suppression (100, 150, 200, 250 pmol/l). From each curve, endometrial volume and thickness thresholds that best predicted pituitary suppression and, separately, non-suppression were selected and the associated sensitivity, specificity, positive and negative predictive values were reported. RESULTS: The area under the curve (AUC) was consistently higher (better test) for 3D volume than thickness estimation for all four estradiol thresholds, although it was only significantly different when a threshold of 200 pmol/l was used. The AUC increased towards 1.0 (perfect test) for both volume and thickness measurement as the selected estradiol threshold increased. Very different volume and thickness thresholds were optimal depending on whether the aim of the test was to predict pituitary suppression or non-suppression. CONCLUSIONS: 3D endometrial volume estimation provides a new tool, alongside endometrial thickness measurement, to diagnose pituitary suppression and non-suppression during IVF. Different endometrial thresholds must be selected depending upon whether the priority is to identify pituitary suppressed, or arguably more importantly, non-suppressed cycles.

Adult↗
PubMed1996

Non-invasive measurement of left ventricular volumes and function by gated positron emission tomography.

To date cardiac positron emission tomography (PET) studies have focussed on the measurement of myocardial blood flow, metabolism and receptors while left ventricular (LV) function and dimensions have been derived from other modalities. The main drawback of this approach is the difficulty of data co-registration, which limits clinical interpretation. The aim of this study was to evaluate whether it is possible to measure absolute cardiac volumes, and consequently LV function parameters such as ejection fraction, and wall motion with gated PET. Nineteen patients underwent a PET scan and planar radionuclide ventriculography (MUGA) within 9+/-9 days. A 9-min scan (16 gates/cardiac cycle) was acquired after inhalation of 3 MBq/ml of oxygen-15 labelled carbon monoxide at the rate of 500 ml/min over 4 min using a multislice PET camera. Noise reduction was performed on the gated image to enhance the definition of the ventricles before reslicing to the short-axis view. A threshold value was used to detect the edge of the LV at each gate. LV volumes at each gate were estimated by summing the volume of voxels within the LV boundary. PET measurements of LV volumes were as follows: LV end-diastolic volume ranged from 72 to 233 ml and LV end-systolic volume ranged from 24 to 203 ml. Phantom experiments supported the validity of this approach for estimating volumes. LV ejection fraction measured with MUGA was 38.4%+/-16.3% (range 15%-71%) and that measured with PET was 39.6%+/-17.7% (range 9%-72%) (P=NS). The LV ejection fraction measurements were highly correlated (r2=0.824). These results indicate that: (1) absolute end-diastolic and end-systolic volumes can be quantified using gated PET and (2) LV ejection fraction can be accurately measured by gated PET simultaneously with the other physiological PET parameters.

Coronary Disease↗
PubMed1980

The ventilatory responses of conscious dogs to isocapnic oxygen tests. a method of exploring the central component of respiratory drive and its dependence on O2 and CO2.

Conscious unrestrained dogs trained to breathe through a respiratory mask or, after chronic tracheostomy, through a cuffed endotracheal tube were studied in an altitude chamber operated in such a way that end-tidal PO2 was maintained at 100, 75 or 60 Torr. Each hypoxic experiment was completed within 1 h of the onset of hypoxia. At all levels of oxygenation, resting pulmonary ventilation (V), obtained from the tidal volume (VT) and ventilatory period (T), and alveolar gas tensions (PAO2, PACO2) were measured cycle-by-cycle before and during isocapnic O2-tests (IOT) at various steady levels of alveolar PCO2 ranging from 30 to 48 Torr. For this, PCO2 in the inspired gas before and during IOT was adjusted so that PACO2 remained unchanged in the course of the first few breaths which followed the switch to hyperoxia. In analysing the transient changes of V in the course IOT, it was considered that an apnoea occurred when there was no measurable deflection on the integrated pneumotachogram past a duration twice the control T from the beginning of the last recorded ventilatory cycle. (1) Control V vs. PACO2 relationships showed classic positive interaction between hypercapnia and hypoxia; (2) during IOT at PAO2 of 100, 75 or 60 Torr, an apnoea occurred, V invariably falling to zero, provided that PACO2 was below 38-35 Torr according to the level of oxygenation; (3) above that threshold PACO2 value, the residual minimum ventilation (Vres) observed during IOT was linearly related to PACO2; (4) Vres vs. PACO2 relationships showed negative interaction between hypercapnia and hypoxia. It is concluded that (a) through isocapnic O2-tests, both the peripheral and central components of the ventilatory drive can be quantitatively estimated; (b) in conscious dogs, the pulmonary ventilation appears to be entirely driven by afferent activity from the arterial chemoreceptors, even in eucapnic normoxia; (c) the lower minimum ventilation seen in the course of O2-tests from a hypoxic rather than a normoxic background is still observed at PACO2 above normal, thus cannot be due only to hypocapnia related to preceding hypoxic hyperventilation must be caused by a central respiratory inhibition directly or indirectly related to depressant effect of even moderate hypoxia.

Animals↗
PubMed2006

Incidence and prediction of ovarian hyperstimulation syndrome in women undergoing gonadotropin-releasing hormone antagonist in vitro fertilization cycles.

OBJECTIVE: To determine the incidence of ovarian hyperstimulation syndrome (OHSS) in a large series of GnRH antagonist-stimulated cycles and to assess the predictive value of E2 and the number of follicles on the day of hCG administration. DESIGN: Prospective cohort study of women undergoing IVF treatment with a GnRH antagonist protocol over a 2-year period. SETTING: Tertiary university hospital. PATIENT(S): One thousand eight hundred one patients who underwent 2,524 cycles. INTERVENTION(S): Multifollicular ovarian stimulation with recombinant FSH and GnRH antagonist for IVF-ICSI treatment. MAIN OUTCOME MEASURE(S): Incidence of OHSS in GnRH antagonist cycles, predictive value of E2, and number of follicles on the day of hCG for OHSS occurrence. RESULT(S): Fifty-three patients were hospitalized because of OHSS (2.1%; 95% confidence interval [CI]:1.6-2.8). Early OHSS presented in 31 patients (1.2%; 95% CI: 0.9-1.8), whereas the late type was a complication in 22 patients (0.9%; 95% CI: 0.5-1.3). Late OHSS cases compared with the early OHSS cases always occurred in a pregnancy cycle (100% vs. 40%); had higher probability of being severe (72.7% vs. 42%), and more often were related to a multiple pregnancy (40% vs. 0). Receiver operating characteristic curve analysis for several E2 concentrations and number of follicles with a diameter of > or =11 mm revealed that the predictive value of the optimal threshold of > or =13 follicles (85.5% sensitivity; 69% specificity) was statistically significantly superior to the optimal threshold of 2,560 ng/L for E2 concentrations (53% sensitivity, 77% specificity) in identifying patients at risk for OHSS. Considering that severe OHSS represents the most clinically significant pattern, the combination of a threshold of > or =18 follicles and/or E2 of > or =5,000 ng/L yields a 83% sensitivity rate with a specificity as high as 84% for the severe OHSS cases. CONCLUSION(S): Clinically significant OHSS still remains a limitation of multifollicular ovarian stimulation for IVF even with the use of GnRH antagonist protocols. The number of follicles can discriminate the patients who are at risk for developing OHSS, whereas E2 concentrations are less reliable for the purpose of prediction. There is more than ever an urgent need for alternative final oocyte maturation-triggering medication.

Adult↗
PubMed1980

Influence of exercise type, hydration, and heat on plasma volume shifts in men.

Four male Caucasians were studied during cycle ergometer exercise and stair stepping in a hot wet environment (32 degrees C db, 30 degrees C wb) after exertion was equated by matching heart rates during training. With each exercise, one session was conducted after 24 h of water deprivation, the other 50 min after ingestion of an amount of water equal to 1% body weight. Venous blood samples were obtained 24 h before each exercise and before and at 10-min intervals during each exercise. No changes in osmolality were found during stair stepping. A progressive osmoconcentration, however, occurred during cycling after dehydration and an initial osmoconcentration with little subsequent change accompanied ergometer exercise after hydration. This latter effect was due to a consistent osmodilution in all subjects, but occurring at different times during the session in each. All attained an osmolality of 290 mosmol/kg before dilution. Because this value is above the threshold of arginine vasopressin release, this hormone may have been responsible for the osmodilution. Therefore, the preexercise osmolality and the rate at which the threshold for vasopressin release is attained may determine whether osmodilution, osmoconcentration, or both occur during exercise.

Acclimatization↗
PubMed1996

Physical and physiological factors associated with success in the triathlon.

The physiological demands of sequential exercise in swimming, cycling and running are unique and require the triathlete to develop physical and physiological characteristics that are a blend of those seen in endurance swimming, cycling and running specialists. Elite triathletes are generally tall, of average to light weight and have low levels of body fat, a physique which provides the advantages of large leverage and an optimal power to surface area or weight ratio. Triathletes have high maximum oxygen uptake (VO2max) values, but VO2max may be on average marginally lower than values previously observed in endurance specialists. Although VO2max is a predictor of performance in triathletes of mixed abilities, it cannot be used to predict performance within homogenous groups of elite performers. Nevertheless, elite triathletes have significantly higher VO2max values than sub-elite triathletes and high VO2max levels are required for success in triathlons. The ability of the triathlete to exercise at a lower percentage of VO2max for a given submaximal workload may be especially important to triathlon success. This is influenced not only by VO2max itself, but also by anaerobic threshold and economy of movement. Anaerobic threshold, as indicated by either ventilatory threshold or lactate threshold, improves with triathlon training and when measured in the appropriate exercise mode has been related to swim, cycle and run performance in the triathlon. Economy of movement in swimming, cycling and running is also related to triathlon performance, and swimming economy in particular appears to be an area where triathletes could make large improvements. Future research should utilise experimental methodologies to investigate triathlon physiology, in particular, the influence of sequential exercise in different exercise modes on physiological function and examine the influence of different training interventions on triathlon physiology and performance.

Anaerobic Threshold↗