Pattern of menstrual cycle length in south Indian women: a prospective study.

Data on 8,308 menstrual cycles from 1,740 South Indian women prospectively recorded were analyzed to identify the effect of age on menstrual cycle length. The distribution was skewed to the right with the mean (SD) cycle length of 31.8 (6.7) days. The range of 25-40 days constituted 10-82 per cent of menstrual cycle lengths. In no age group did 28-day cycles occur in more than 9 per cent of women. Variability as measured by the standard deviation was high among those below 19 years of age, stabilized during 25-39 years, and then increased in women aged 40 years or more. The findings are discussed in the light of other studies and possible implications in fertility control programs.     

Pattern of menstrual cycle length in South Indian women: A prospective study

Abstract

Data on 8,308 menstrual cycles from 1,740 South Indian women prospectively recorded were analyzed to identify the effect of age on menstrual cycle length. The distribution was skewed to the right with the mean (SD) cycle length of 31.8 (6.7) days. The range of 25–40 days constituted 10–82 per cent of menstrual cycle lengths. In no age group did 28‐day cycles occur in more than 9 per cent of women. Variability as measured by the standard deviation was high among those below 19 years of age, stabilized during 25–39 years, and then increased in women aged 40 years or more. The findings are discussed in the light of other studies and possible implications in fertility control programs.     

The resting frontal alpha asymmetry across the menstrual cycle: a magnetoencephalographic study

Gonadotropic hormones play an important role in the regulation of emotion. Previous studies have demonstrated that estrogen can modulate appetitive (approach/positive) and aversive (avoidance/negative) affective behaviors during the menstrual cycle. Frontal alpha asymmetry (a measure of relative difference of the alpha power between the two anterior hemispheres) has been associated with the trait and state reactivity of different affective styles. We studied the pattern change of frontal alpha asymmetry across the menstrual cycle. 16 healthy women participated in this resting magneto-encephalographic (MEG) study during the peri-ovulatory (OV) and menstrual (MC) phases. Our results showed significant interaction of resting MEG alpha activity between hemispheric side and menstrual phases. Difference in spontaneous frontal alpha asymmetry pattern across the menstrual cycle was also noted. Relatively higher right frontal activity was found during the OV phase; relatively higher left frontal activity was noted during the MC phase. The alteration of frontal alpha asymmetry might serve a sub-clinical correlate for hormonal modulation effect on dynamic brain organization for the predisposition and conceptualization of different affective styles across the menstrual cycle.     

Human sex ratio as a function of the timing of insemination within the menstrual cycle: a review

A review of the beliefs and research results on the influence of the time of insemination on the sex ratio is presented. The ancient Greek notion that more males were produced by early postmenstrual insemination was supported as late as the early 1900s, although, by then, that belief was not uncontested. The view soon changed to the one of Dechman in which midcycle insemination favored the birth of males because of the deterioration of the ovum and other dominance/submission arguments. There were also some 20th century writers who recommended premenstrual insemination for producing male offspring. More recent thinking, taking advantage of new knowledge in reproductive physiology, holds that insemination immediately prior to ovulation favors males, whereas earlier insemination favors females. Artifical insemination of women 3 or more days before ovulation has been reported to result in an excess of females, while natural insemination during the same time-frame produced an excess of males. More clinical research, utilizing a uniform methodology for determining the time of ovulation, is needed to elucidate the relationship between the date of insemination, menstrual-cycle day, and sex outcome to the sex ratio. Possible causes for natural variations in the sex ratio should also be investigated.     

Women's behavioural engagement with a masculine male heightens during the fertile window: evidence for the cycle shift hypothesis

Previous research suggests that women may alter their behaviour during the fertile window of the menstrual cycle to attract a mate who has traits that indicate high-quality genes. We tested whether fertile women demonstrate greater behavioural engagement with a masculine compared to a less masculine male. The test was performed using a quiz show paradigm, in which a male host asked female participants general knowledge questions. The masculinity of the host was varied between participants. Women's performance on the quiz, as well as their romantic attraction to the host, was examined in relation to women's estimated cycle phase and host masculinity. Fertile compared to nonfertile women were more romantically attracted to the host and were faster to answer his questions, but only when he was portrayed as masculine. The results of the study are interpreted as being in keeping with Gangestad and Thornhill's cycle shift hypothesis (Menstrual cycle variation in women's preferences for the scent of symmetrical men. Proceedings of the Royal Society of London B: Biological Sciences, 1998;265:727–733. doi:10.1098/rspb.1998.03801998).     

Integrin cell adhesion molecules in endometrium of fertile and infertile women throughout menstrual cycle

Integrins (ITGs) are ubiquitous cell adhesion molecules that undergo dynamic alterations during the normal menstrual cycle in human endometrium. The distribution of four different subunits, viz. alpha 4, alpha 6, beta 3 and beta 4 in human endometrial tissue at different stages of the menstrual cycle was studied using immunohistochemical, enzyme immunoassay and SDS-PAGE/Western blot techniques. The specificity of each mAb to their respective ligands viz., laminin (Ln), fibronectin (Fn) and vitronectin (Vn) was done by cell adhesion assays. Both alpha 6 and beta 4 subunits (Ln receptors) expressed primarily on the glandular epithelium, while glandular, stromal and luminal cells expressed predominantly alpha 4 (Fn receptor) and beta 3 (Vn receptor). The appearance of alpha 4 and beta 3 ITG subunits was found to be cell and cycle specific. The levels of both alpha 6 and beta 4 increased throughout the menstrual cycle, while beta 3 subunit appeared abruptly on cycle day 19/20. The immunostaining for alpha 4 and beta 3 was absent in 90% of infertile women. The timing of expression of alpha 4 and beta 3, the two cycle--dependent ITGs framed the putative window of implantation and suggests a role in the diagnosis of infertility. In conclusion, the absence of alpha 4 and beta 3 ITG expression in the endometrium of infertility subjects during mid luteal phase may be associated with defects in uterine function. The defective uterine receptivity may be an unrecognised cause of infertility in these group of women.     

Temperament and ovarian reproductive hormones in women: evidence from a study during the entire menstrual cycle

Personality and temperament were hypothesized to function as important factors affecting life history strategies. Recent research has demonstrated the association between temperamental traits and reproduction in humans, however, the underlying mechanisms are still poorly understood. This study presents evidence for an association between temperamental traits and woman's fecundity, as indicated by levels of ovarian steroid hormones during the menstrual cycle. On a large sample of urban, reproductive age women (n = 108) we demonstrated that activity, endurance and emotional reactivity are associated with levels of estrogen and with a pattern of change of progesterone levels. Women high in activity, high in endurance and low in emotional reactivity had up to twice as high estradiol levels and more favorable progesterone profiles as women low in activity, low in endurance and high in emotional reactivity. The temperamental traits we measured highly overlap with extraversion, neuroticism and negative emotionality that were reported to correlate with reproductive success. Our findings thus suggest a possible explanation for these relationships, linking personality and women's reproductive success through a hormonal pathway.     

Redistribution of adhering junctions in human endometrial epithelial cells during the implantation window of the menstrual cycle

The human uterine epithelium is characterised by remarkable plasticity with cyclic changes in differentiation that are controlled by ovarian steroid hormones to optimise conditions for embryo implantation. To understand whether and how cell-cell adhesion is affected, the localisation of junction proteins was studied throughout the menstrual cycle. Expression patterns were examined by immunofluorescence in 36 human endometrial specimens of different cycle stages. Antibodies against the desmosomal proteins desmoplakin 1/2 (Dp 1/2) and desmoglein 2 (Dsg 2), the adherens junction proteins E-cadherin and β-catenin and also the common junctional linker protein plakoglobin showed a strong subapical staining during the proliferative phase until the early luteal phase (day 20). In the mid- to late luteal phase, however, these junctional proteins redistributed over the entire lateral plasma membranes. In contrast, tight junction proteins (ZO-1, claudin 4) remained at their characteristic subapical position throughout the menstrual cycle. mRNA levels of Dp 1/2, E-cadherin and ZO-1 obtained by real time RT-PCR were not significantly changed during the menstrual cycle. The observed redistribution of desmosomes and adherens junctions coincides with the onset of the so called implantation window of human endometrium. We propose that this change is controlled by ovarian steroids and prepares the endometrium for successful trophoblast invasion.     

The timing of the cognitive cycle

We propose that human cognition consists of cascading cycles of recurring brain events. Each cognitive cycle senses the current situation, interprets it with reference to ongoing goals, and then selects an internal or external action in response. While most aspects of the cognitive cycle are unconscious, each cycle also yields a momentary "ignition" of conscious broadcasting. Neuroscientists have independently proposed ideas similar to the cognitive cycle, the fundamental hypothesis of the LIDA model of cognition. High-level cognition, such as deliberation, planning, etc., is typically enabled by multiple cognitive cycles. In this paper we describe a timing model LIDA's cognitive cycle. Based on empirical and simulation data we propose that an initial phase of perception (stimulus recognition) occurs 80-100 ms from stimulus onset under optimal conditions. It is followed by a conscious episode (broadcast) 200-280 ms after stimulus onset, and an action selection phase 60-110 ms from the start of the conscious phase. One cognitive cycle would therefore take 260-390 ms. The LIDA timing model is consistent with brain evidence indicating a fundamental role for a theta-gamma wave, spreading forward from sensory cortices to rostral corticothalamic regions. This posteriofrontal theta-gamma wave may be experienced as a conscious perceptual event starting at 200-280 ms post stimulus. The action selection component of the cycle is proposed to involve frontal, striatal and cerebellar regions. Thus the cycle is inherently recurrent, as the anatomy of the thalamocortical system suggests. The LIDA model fits a large body of cognitive and neuroscientific evidence. Finally, we describe two LIDA-based software agents: the LIDA Reaction Time agent that simulates human performance in a simple reaction time task, and the LIDA Allport agent which models phenomenal simultaneity within timeframes comparable to human subjects. While there are many models of reaction time performance, these results fall naturally out of a biologically and computationally plausible cognitive architecture.     

Variations in the concentrations of androstenedione in peripheral plasma of women the day and during the menstrual cycle

The target tissues (e.g., hypothalamus, pituitary, uterus and vagina) of mature female ovariectomized rats show selective uptake of radioactivity in one hour after the injection of 6,7, ³H-estradiol-17β in a dose of 0.1 μg per 100 g body weight. Injection of 100 μg norethindrone or norgestrel per 100 g body weight 15 min before or 15 min after the administration of tritiated estradiol reduced the radioactivity in most target tissues, and also in the non-target tissues to a lesser extent. The uptake of radioactivity in the pituitary and uterus is reduced more by norethindrone than by norgestrel treatment when these Steroids were injected 15 min after estradiol-17β injection. It appears that there exists a competitive inhibition of estradiol-17β by these contraceptive Steroids in the rat. It is speculated that such competition with estradiol-17β may be an inherent property of the 17-substituted 19-nortestosterone group of Steroids.     

The presence of endometrial cells in cervical smears in relation to the day of the menstrual cycle and the method of contraception

The presence of endometrial cells in cervical smears was studied in a large series of women participating in a population screening program for cervical cancer, in relation to different time periods of the menstrual cycle and to the method of contraception practiced. In the total group of women studied, endometrial cells were present in an average of 12% of the cervical smears. In women who were menstruating cyclically, the percentage of cervical smears containing endometrial cells was not age dependent. Only in women over 52 years was a lower number of endometrium-positive cervical smears found: in postmenopausal women, 0.6% of smears were found to contain endometrial cells. In menstruating women, the frequency of endometrial cells in cervical smears was highest during the menses. After day four, through the proliferative phase, the percentages of cervical smears containing endometrial cells markedly decreased. During the secretory phase, an average of 2% of the smears contained endometrial cells; in the premenstrual phase (after day 25), the percentages of endometrial cell-positive smears rose again. When related to the method of contraception practiced, significant differences in the percentages of cervical smears with endometrial cells appeared. In women using oral hormonal contraceptives, the average numbers of smears containing endometrial cells for the whole cycle as well as for each period of the cycle were significantly lower. This phenomenon might be due to endometrial atrophy on the basis of prolonged use of oral hormonal contraceptives. In women wearing an intrauterine device, at any moment the frequencies of smears with endometrial cells present were significantly higher than the values found in women using any other method of contraception or not using contraceptives. The evaluation of cells originating from the endometrium requires considerable experience. The identification of endometrial cells can be made with greater confidence when the cytologist is aware of the exact date of the menstrual cycle and of the impact on the presence of endometrial cells in cervical smears caused by different methods of contraception.     

The distribution of events in the human menstrual cycle

Daily reports of 85 married couples concerning their sexual behaviour for about 3 menstrual cycles per couple were organized according to menstrual events by using six techniques of aggregation. While there were some similarities among the different displays, including an apparent peak about 6 days before mid-cycle, different methods of aggregation produce widely different frequency curves. It is concluded that there is no single method of display of events of the menstrual cycle which will fit all investigations.     

Cellular composition of cervical smears in relation to the day of the menstrual cycle and the method of contraception

The influence of the day of the menstrual cycle and the method of contraception on the cellular composition of cervical smears was investigated. The percentage of unsatisfactory smears during the first four days of the cycle was understandably very high, leaving only 80% of the smears of sufficient quality for cytologic diagnosis. The percentage of smears of insufficient quality during the remainder of the cycle was significantly higher in women using oral hormonal contraceptives. The percentages of smears containing endocervical columnar cells, a criterion for judging smears to be of high quality, differed significantly among women using different modes of contraception. The highest percentage of smears without endocervical columnar cells was found in women using oral contraceptives; during the first half of the cycle in these women, smears were of higher quality than during the second half of the cycle. In women not practicing contraception or using nonhormonal methods of contraception, the differences in cellular composition during the cycle, though significant, were too small to be of practical importance. Women using oral contraceptives thus have an increased risk for a potential false-negative diagnosis because of the higher percentage of smears of unreliable quality taken in these women. In women using oral hormonal contraceptives, smears should be taken during the first half of the cycle because of the higher percentage of smears of high quality in that period.     

The effect of training at a specific time of day: a review

This article focuses on physical performances after training at a specific time of day. To date, although the effect of time of day on aerobic performances appears to be equivocal, during anaerobic exercises, the effect of time of day has been well established with early morning nadirs and peak performances in the late afternoon. These diurnal rhythms can be influenced by several factors such as the regular training at a specific time of day. Indeed, regular training in the morning hours may increase the lower morning performances to the same or even higher level as their normal diurnal peak typically observed in the late afternoon by a greater increase of performance in the evening. However, regular training in the evening hours may increase the morning-evening (i.e., amplitude of the rhythm) difference by a greater increase of performance in the late afternoon. Therefore, adaptations to training are greater at the time of day at which training is regularly performed than at other times. Nevertheless, although modifications in resting hormones concentrations could explain this time-of-day specific adaptations, precise information on the underlying mechanisms is lacking.     

Effects of time of day, gender, and menstrual cycle phase on the human response to a water load

Estrogen and progesterone interference with renal actions of arginine vasopressin (AVP) has been shown. Thus we hypothesized that women will have a higher water turnover than men and that the greatest difference will be during the luteal phase of the menstrual cycle. Seven men (32 +/- 3 yr) and six women (33 +/- 2 yr) drank 12 ml water/kg lean body mass on different days at 0800 and at 2000 following 10 h of fast and a standardized meal at 0600 and 1800. Women participated on days 4-11 and 19-25 of the menstrual cycle. Initial urine and plasma osmolalities and urine flow rates were similar in all experiments. The cumulative urine voided over 3 h following the morning drink was less in men (73 +/- 12% of the water load) compared with women in either the follicular (100 +/- 3%) or luteal phases (102 +/- 10%) of the menstrual cycle. Nighttime values (30-43% of the water load) were lower in all experiments and were not different between sexes or menstrual cycle phases. Plasma AVP was higher at night and may contribute to this diurnal response. The data are generally consistent with the stated hypothesis; however, possibly owing to the greatly reduced urine flow in both sexes at night, a difference between sexes was not observed at that time.     

Tight junctions of human uterine epithelial cells change during the menstrual cycle: a morphometric study.

Tight junctions between luminal epithelial cells of the human uterus were studied by freeze-fracture electron microscopy. It was found that junctional complexity decreased during the menstrual cycle, and we explore how this finding may contribute to the role of the uterus in facilitating implantation.     

The dopaminergic inhibition of LH secretion during the menstrual cycle

To assess the potential inhibitory role of hypothalamic dopaminergic input on the LRF-LH system, the gonadotropin response to a dopamine receptor antagonist, metoclopramid (MCP, 10 mg iv bolus) was examined during different phases of the menstrual cycle in 12 women. In addition, the role of dopamine infusion on naloxone (opiate receptor antagonist) induced LH increments was examined. MCP induced an abrupt increase in circulating LH levels in the mid-luteal phases but not in the early and late follicular phase subjects. No significant changes in serum FSH levels were observed. Dopamine, when infused concomitantly with naloxone, completely suppressed the naloxone induced pulsatile increments of LH in mid-luteal subjects. These findings support the contention that an increased dopaminergic inhibition of LRF-LH system occurs during the high estrogen-progesterone phase of the menstrual cycle, and provide preliminary evidence that the inhibitory role of endogenous opioids on LRF release may involve the dopaminergic system.