Phase-related Differences Research Articles

Diurnal preference, sleep habits, circadian sleep propensity and melatonin rhythm in healthy human subjects

After 24-h sleep deprivation, 33 healthy young subjects entered the 10/20 min ultra-short sleep–wake schedule for 26 h. Melatonin rhythm was hourly assessed simultaneously. Results indicated that morning preference was significantly correlated with habitual sleep onset ( r=−0.41, P=0.04), habitual sleep offset ( r=−0.52, P=0.002), melatonin peak time ( r=−0.36, P=0.04), and sleep propensity onset time ( r=−0.36, P=0.04). The intervals between habitual sleep mid-point and melatonin peak time and between habitual sleep mid-point and sleep propensity onset time were significantly longer in morning-preference subjects than in evening-preference subjects ( P<0.05). These findings suggest that the variance of diurnal preference may be related to differences in phase relations between habitual sleep timing and the circadian pacemaker.

Concomitant mandibular and head-neck movements during jaw opening-closing in man.

To test the hypothesis of a functional relationship between the human mandibular and cranio-cervical motor systems, head-neck movements during voluntary mandibular movements were studied in 10 healthy young adults, using a wireless optoelectronic system for three-dimensional (3D) movement recording. The subjects, unaware of the underlying aim of the study, were instructed to perform maximal jaw opening-closing tasks at fast and slow speed. Movements were quantified as 3D movement amplitudes. A consistent finding in all subjects was parallel and coordinated head-neck movements during both fast and slow jaw opening-closing tasks. Jaw opening was always accompanied by head-neck extension and jaw closing by head-neck flexion. Combined movement and electromyographic recordings showed concomitant neck muscle activity during head-neck movements, indicative of an active repositioning of the head. No differences in 3D movement amplitudes could be seen with respect to speed. The head movement was 50% of the mandibular movement during jaw opening, but significantly smaller (30-40%), during the jaw closing phase. In repeated tests, the 3D movement amplitudes of the concomitant head movements were less variable during slow jaw movement and during the jaw opening phase, than during fast and jaw closing movements, suggesting speed- and phase-related differences in the mechanisms controlling the integrated mandibular and head-neck motor acts. The present results give further support to the concept of a functional trigeminocervical coupling during jaw activities in man.

Immunohistochemical distribution of follistatin in dominant and subordinate follicles and the corpus luteum of cattle.

The study was done to quantitatively characterize the distribution of follistatin in ovarian follicles and corpora lutea at specific stages of development. Transrectal ultrasonography was used to monitor the growth of individually identified follicles from 2 days before ovulation until the day of ovariectomy on Day 3 of wave 1 (n = 8), Day 6 of wave 1 (n = 6), Day 1 of wave 2 (n = 6), or after onset of proestrus, at least 17 days postovulation (n = 7). Days of ovariectomy represent the growing, early-static, late-static, and regressing phases of the dominant follicle of wave 1, respectively. Subordinate (n = 24), preselection (n = 15), and preovulatory (n = 6) follicles and corpora lutea (n = 31) were also analyzed. Follistatin was localized using immunohistochemical labeling of paraffin sections, and relative amounts were quantitated using densitometric analysis. Follistatin was distributed in the perinuclear cytoplasm of granulosa and luteal cells but not in theca cells. Dominant follicles contained more (p < 0.05) follistatin than corresponding subordinate follicles. The amount of follistatin was maximal during the mid-growing phase of the dominant follicle and decreased thereafter (p < 0.05). Among the corpora lutea, the maximal amount was detected at mid-diestrus (Day 11 postovulation). Less than half of luteal cells displayed the stain for follistatin; positively stained luteal cells were located in close proximity to blood capillaries. Follistatin was not detectable in the corpus luteum during metestrus (Day 3 postovulation) or proestrus (Day >/= 17 postovulation). In summary, the degree of immunohistochemical expression of follistatin was phase specific for both follicles and corpora lutea. The most intense staining in follicles was associated with the period of functional dominance and in corpora lutea was seen during the phase of maximal development. Significant phase-related differences in follistatin expression provide rationale for the hypothesis that follistatin is involved in the final stages of follicle and luteal gland development in cattle.

Assessment of protein permeability in normal human systemic circulation

Vascular permeability to oncotic agents is an important determinant of transvascular fluid flux (J) and systemic fluid balance. In this study, a technique was developed to measure protein reflection coefficients (omega) for albumin (Alb), immunoglobulin (Ig) G, and IgM in the intact human systemic circulation to evaluate the role of vascular protein permeability in health and disease. A mathematical model was developed to calculate omega in the forearm circulation from changes in venous hematocrit and protein concentration that occur during edema formation. Assumptions required for the model were validated in an initial set of experiments in normal subjects when edema was induced by inflating a pneumatic cuff on the upper arm. A second series of experiments assessed omega for Alb, IgG, and IgM in men (n = 7) and in women in the follicular (n = 5) and luteal (n = 4) phases of the menstrual cycle. There was an increasing trend in omega with molecular size in aggregated subjects [omega Alb = 0.81 +/- 0.12 (SE), omega IgG = 0.88 +/- 0.12, omega IgM = 0.92 +/- 0.18; P = 0.088]. These values were consistent with those obtained with in vitro preparations. omega values were lower in women in the luteal than in the follicular phase (P = 0.047). We conclude that the assumptions required for this model can be achieved in the intact forearm circulation and that there are menstrual phase-related differences in vascular protein permeability in normal women.

The application of positron emission tomography to the study of the normal menstrual cycle.

Positron emission tomography (PET) was used to investigate regions of the brain that are selectively affected during different phases of the normal menstrual cycle. A total of 10 healthy 18-29 year old female volunteers had PET measurements of brain glucose metabolism between days 5 and 9 of the follicular phase when plasma concentrations of oestradiol and progesterone were relatively low and between days 5 and 8 of the luteal phase when plasma concentrations of oestradiol and progesterone were relatively high. Automated algorithms were used to align the PET images in each individual, transform them into the coordinates of a brain atlas, control for variations in whole brain measurements and compute t-score maps of phase-related differences in regional glucose metabolism. The mid-follicular phase was associated with significantly higher glucose metabolism in thalamic, prefrontal, temporoparietal and inferior temporal regions. The mid-luteal phase was associated with significantly higher glucose metabolism in superior temporal, anterior temporal, occipital, cerebellar, cingulate and anterior insular regions. While this study should be considered to be exploratory, it provides normative data for future studies and illustrates how PET can be used to help characterize relationships between phases of the female life cycle, temporally related disorders and local functions of the living human brain.

Effects of menstrual phase on nicotine, alcohol, and caffeine intake in smokers.

To determine whether cigarette smoking and other drug use are affected by menstrual phase, daily diaries rating menstrual symptomatology, smoking, and alcohol and caffeine intake in female smokers were examined. Women with premenstrual symptomatology were excluded. Menstrual symptomatology peaked during menses and was accounted for primarily by symptoms indicative of physical discomfort. Smoking did not differ as a function of menstrual phase, nor did there emerge any systematic intrasubject correlation between symptomatology and smoking. Alcohol and caffeine intake also failed to show phase-related differences. It was concluded that substance intake is highly stable across the menstrual cycle in female smokers.

Mood effects of alcohol and expectancies across the menstrual cycle

To examine menstrual cycle phase variations in alcohol absorption and mood before and after drinking alcohol, 96 volunteer female heavy drinkers, unaware they were in a menstrual cycle study, were randomly assigned to 12 equal-sized groups with controls for the effects of alcohol, expectancy, and menstrual cycle phase. Alcohol subjects received sufficient alcohol to raise their blood alcohol level to .07 mg %. Mood, assessed with the Profile of Mood States, did not differ across menstrual cycle phases at baseline, failing to support the notion of menstrual phase-related moods. The only mood changes were a Beverage by Trials interaction on the Vigor and Confusion scales and a main effect for trials on the Tension-Anxiety and Vigor scales. Peak intoxication level did not differ across phases. The present findings of an absence of menstrual cycle phase-related differences in mood or alcohol absorption support social learning theory and suggest that phasic variations in mood are socially learned. They also suggest the need for systematic study of methodologic factors in this research area.

Influence of the menstrual cycle and oral contraceptives on thermoregulatory responses to exercise in young women.

Thermoregulatory responses to exercise in relation to the phase of the menstrual cycle were studied in ten women taking oral contraceptives (P) and in ten women not taking oral contraceptives (NP). Each subject was tested for maximal aerobic capacity (VO2max) and for 50% VO2max exercise in the follicular (F) and luteal (L) phases of the menstrual cycle. Since the oral contraceptives would have prevented ovulation a quasi-follicular phase (q-F) and a quasi-luteal phase (q-L) of the menstrual cycle were assumed for P subjects. Exercise was performed on a cycle ergometer at an ambient temperature of 24 degrees C and relative air humidity of 50%. Rectal (Tre), mean skin (Tsk), mean body (Tb) temperatures and heart rate (fc) were measured. Sweat rate was estimated by the continuous measurement of relative humidity of air in a ventilated capsule placed on the chest, converted to absolute pressure (PH2Ochest). Gain for sweating was calculated as a ratio of increase in PH2Ochest to the appropriate increase in Tre for the whole period of sweating (G) and for unsteady-state (Gu) separately. The VO2max did not differ either between the groups of subjects or between the phases of the menstrual cycle. In P, rectal temperature threshold for sweating (Tre,td) was 37.85 degrees C in q-L and 37.60 degrees C in q-F (P < 0.01) and corresponded to a significant difference from Tre at rest. The Tre, Tsk, Tb and fc increased similarly during exercise in q-F and q-L. No menstrual phase-related differences were observed either in the dynamics of sweating or in G.(ABSTRACT TRUNCATED AT 250 WORDS)

Time-budgeting and foraging strategy of the stoplight parrotfish Sparisoma viride Bonnaterre, in Jamaica

Quantitative data on the ways in which the different phases of the stoplight parrotfish ( Sparisoma viride Bonnaterre) distribute their time among various activities in different habitats are presented. Individuals spent from 84–97% of their diurnal time swimming, feeding, and hovering. Additionally, large adults spent a significant amount of time sheltering among crevices. Phase-related differences in these activities are statistically significant, as are differences in duration and rates of change of the activities. Large individuals spent more time swimming, while small individuals spent more time hovering. In addition, large individuals performed longer bouts of activity and switched activities less frequently than small individuals. Adult males and females spent approximately equal proportions of time in each of the activity states. Stochastic analyses of behavioural sequences show second order Markov chain dependencies, suggesting that preceding activity states affect subsequent behaviour. Possible relationships between behavioural sequencing and the species foraging strategy are discussed, and it is suggested that the sequence of behavioural activities can provide an estimation of the distribution of food resources in the environment.

Octopamine distribution in solitarious and gregarious forms of the locust, Schistocerca Americana gregaria

The distribution of octopamine has been examined in the solitarious and gregarious forms of the locust, Schistocerca americana gregaria. No evidence was obtained of any phase-related differences in octopamine levels in nervous tissue or muscle. Octopamine values measured for whole heads agreed well with the sums of their component parts. The results are discussed in relation to previous claims of phase-related changes in octopamine levels.

Application of phase detection and averaging techniques in computer analysis of EEG records in the cat

Consistency of phase patterns in EEG records from the hippocampal system and midbrain reticular formation have been examined in the course of behavioral training in five cats with implated electrodes. These studies have involved novel application of computing techniques, including continuous measurement of phase and amplitude characteristics of single wave trains by digital filtering techniques, the use of cross-spectral analyses with calculation of complex transfer functions, and averaging of records during repeated behavioral performances with calculation of coherence functions in cross-spectral examinations. It was found that rhythmicity appeared in the computed average at the rate of the dominant EEG frequency as T-maze performance reached a high level, and was related to a reduction in scatter in phase patterns at high performance levels. Reversal of behavioral cues was associated with an immediate brief increase in rhythmicity of the average, then a decline followed by a progressive reemergence of rhymicity at the end of retraining. Continuous phase-and-amplitude examinations during delayed response performance indicated a rhythmic phase modulation on wave trains with an apparently single frequency appearing during periods of discrimination. Comparison of probability bounds in cross-spectral analysis with use of a polar coordinate display have indicated major differences in phase relations between different hippocampal regions between correct responses in certain circumstances, with consistency in different examinations. These findings are discussed in relation to a stochastic model of the cerebral system, with reference to the possible role of the wave process in handling and storage of information.