Quantitative histomorphometric analysis of gonadal steroid receptor distribution in the normal human endometrium through the menstrual cycle

The aim of this study was to test the hypothesis that the distribution of oestrogen receptor beta (ER) and androgen receptor (AR) are related to cell proliferation or correlated with the expression of progesterone receptor (PR) or oestrogen receptor alpha (ER) in the normal human endometrium. Immunohistochemical distribution of immunoreactive ER in well-characterised menstrual cycle biopsy samples was lowest in proliferative endometrial glands, highest in early secretory phase glands and maintained at ~20% throughout the rest of the menstrual cycle and was closely correlated with stromal AR and stromal ER expression. Stromal ER was not significantly altered until the menstrual phase of the cycle and was not correlated with the expression of any other antigen in the stroma or endometrial glands except stromal AR. By contrast, glandular AR immunoreactivity was below 5% early in the cycle, increased during the secretory phase and showed strong expression just before menstruation. PR and Ki-67 expression showed strong positive correlations, indicating that PR may be a potent regulator of endometrial proliferation. These data suggest that glandular ER expression is closely associated with a functional secretory role whereas glandular ER and PR are associated with proliferation; glandular AR expression may be the switch required for menstruation.     

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.     

Importance of an appropriate visual presentation for avoiding a misconception of the menstrual cycle

Family planning, the prevention of unwanted pregnancy, and women’s reproductive health are topics that have received close attention for decades. It would therefore be fair to assume that there exists a good knowledge of the menstrual cycle. However, it is clear that many people have various misconceptions about the menstrual cycle and fertile days or ovulation, and that this process is still largely taught with the aid of materials and images that have not changed for many years. We investigated the effect of moving away from the usual teaching practice of using a 28-day diagram showing ovulation on the 14th day. A total of 184 students from three different high schools, aged between 17 and 18, participated in this research. The students who were taught using three diagrams showing different durations of the menstrual cycle showed a significantly better adoption of the facts and concepts compared to the students who were taught using a diagram of the average 28-day cycle. Our results confirmed that it is highly important to use appropriate visual displays in the teaching of the menstrual cycle and that it is essential to enhance the visual literacy of students and teachers.     

Global asymptotic stability of the size distribution in probabilistic models of the cell cycle

Probabilistic models of the cell cycle maintain that cell generation time is a random variable given by some distribution function, and that the probability of cell division per unit time is a function only of cell age (and not, for instance, of cell size). Given the probability density, f(t), for time spent in the random compartment of the cell cycle, we derive a recursion relation for _n(x), the probability density for cell size at birth in a sample of cells in generation n. For the case of exponential growth of cells, the recursion relation has no steady-state solution. For the case of linear cell growth, we show that there exists a unique, globally asymptotically stable, steady-state birth size distribution, _*(x). For the special case of the transition probability model, we display _*(x) explicitly.This work was supported by the National Science Foundation under grants MCS8301104 (to J.J.T.) and MCS8300559 (to K.B.H.), and by the National Institutes of Health under grant GM27629 (to J.J.T.).     

Physiological variation in estradiol and brain function: a functional magnetic resonance imaging study of verbal memory across the follicular phase of the menstrual cycle

Women frequently complain of memory problems at times in their reproductive lives that are associated with changes in estrogen concentration (e.g. around menopause and childbirth). Further, behavioural studies suggest that memory performance may fluctuate across the menstrual cycle. For example, performance on verbal tasks has been reported to be greatest during phases associated with high estrogen concentrations whereas the opposite has been reported with visuo-spatial tasks. The biological basis of these reported effects remains poorly understood. However, brain imaging studies into the effects of estrogen therapy in postmenopausal women suggest that estrogen modulates the metabolism and function of brain regions sub-serving memory. Furthermore, we have recently reported that acute suppression of ovarian function in young women (with a Gonadotropin Hormone Releasing Hormone agonist) is associated with decreased activation in left prefrontal cortex, particularly the left inferior frontal gyrus (LIFG), during successful verbal memory encoding. We therefore investigated whether physiological variation in plasma estradiol concentration is associated with differences in activity of the LIFG during successful verbal encoding. We hypothesised that higher plasma concentrations of estradiol would be associated with increased brain activity at the LIFG and improved recall performance. Although we did not find a significant relationship between plasma estradiol concentration and verbal recall performance, we report a positive correlation between brain function and estradiol concentration at the LIFG.     

Comet assay responses in human lymphocytes are not influenced by the menstrual cycle: a study in healthy Indian females

The single-cell gel electrophoresis or Comet assay measures qualitative and quantitative DNA damage in single cells. Its simplicity and non-invasive nature has made it widely accepted for the monitoring of human genotoxicity, employing peripheral blood lymphocytes. Factors, such as gender, age, and dietary and smoking habits are known to affect the Comet assay responses in lymphocytes. However, there is no information regarding the influence of the menstrual cycle on the results of the assay in lymphocytes of females.A study was therefore undertaken among 18 healthy Indian female volunteers to assess the effect of the menstrual cycle on Comet assay responses. During a complete menstrual cycle, only minor changes were observed in the basal levels of DNA damage in the lymphocytes as evident by Comet parameters, such as tail length (μm), tail DNA (%) and Olive tail moment (arbitrary units).To assess the effect of the estrogen 17β-estradiol (at physiological concentrations of 0.5, 1.0 and 2.0 nM) on the Comet assay responses, an in vitro study was conducted in the human lymphocyte cell line JM-1 and the breast cancer cell line MCF-7. As was evident from the Comet parameters, a significant (p < 0.01) concentration-dependent increase in the level of DNA damage was observed in the MCF-7 cells while no significant change was found in the JM-1 cells.The results indicate that the menstrual cycle does not influence the Comet assay responses in lymphocytes; hence, these can serve as a model for monitoring genotoxicity in females.     

A detailed model and Monte Carlo simulation for predicting DIP genome length distribution in baculovirus infection of insect cells

Baculoviruses have enormous potential for use as biopesticides to control insect pest populations without the adverse environmental effects posed by the widespread use of chemical pesticides. However, continuous baculovirus production is susceptible to DNA mutation and the subsequent production of defective interfering particles (DIPs). The amount of DIPs produced and their genome length distribution are of great interest not only for baculoviruses but for many other DNA and RNA viruses. In this study, we elucidate this aspect of virus replication using baculovirus as an example system and both experimental and modeling studies. The existing mathematical models for the virus replication process consider DIPs as a lumped quantity and do not consider the genome length distribution of the DIPs. In this study, a detailed population balance model for the cell‐virus culture is presented, which predicts the genome length distribution of the DIP population along with their relative proportion. The model is simulated using the kinetic Monte Carlo algorithm, and the results agree well with the experimental results. Using this model, a practical strategy to maintain the DIP fraction to near to its maximum and minimum limits has been demonstrated.     

Constructing normalcy and discrepancy indexes for birth weight and gestational age using a threshold regression mixture model

Birth weight and gestational age are important measures of a newborn's intrinsic health, serving both as outcome measures and explanatory variables in health studies. The measures are highly correlated but occasionally inconsistent. We anticipate that health researchers and other scientists would be helped by summary indexes of birth weight and gestational age that give more precise indications of whether the birth outcome is healthy or not. We propose a pair of indexes that we refer to as the birth normalcy index or BNI and birth discrepancy index or BDI. Both indexes are simple functions of birth weight and gestational age and in logarithmic form are orthogonal by construction. The BNI gauges whether the birth weight and gestational age combination are in a normal range. The BDI gauges whether birth weight and gestational age are consistent. We present a three-component mixture model for BNI, with the components representing premature, at-risk, and healthy births. The BNI distribution is derived from a stochastic model of fetal development proposed by Whitmore and Su (2007, Lifetime Data Analysis 13, 161-190) and takes the form of a mixture of inverse Gaussian distributions. We present a noncentral t-distribution as a model for BDI. BNI and BDI are also well suited for making comparisons of birth outcomes in different reference populations. A simple z-score and t-score are proposed for such comparisons. The BNI and BDI distributions can be estimated for births in any reference population of interest using threshold regression.     

The distribution,life cycle and production of Leptophlebia vespertina (L.) (Ephemeroptera) in a lowland lake

Oak Mere, the water body studied, is a moderately productive base-poor lowland lake. It has zones of submerged marginal vegetation growing on sand at the south-west end and on peat at the north-east end. The distributions of L. vespertina and other macroinvertebrates are described in relation to these two distinct areas. Laboratory experiments on behaviour and survival are described in an attempt to explain the patterns of distribution. The seasonal distribution, variations in population density, spatial distribution variance in relation to mean density, life cycle, length-weight relationship, growth and biomass of L. vespertina are then described during two years at the sandy south-west end. The data are used to estimate annual production. Distribution, life cycle, growth and production are compared with populations in water bodies of lower conductivity in the British Isles and Scandinavia.     

Life cycle assessment of district heat distribution in suburban areas using PEX pipes insulated with expanded polystyrene

Goal, Scope and Background

Combined heat and power (CHP) is a strategy aimed at reducing the impact of the energy sector on the climate by more efficient use of the energy content of the fuel. The implementation of CHP requires the utilisation of the heat produced. Space heating by means of district heating is one possible use for such heat. In countries such as Sweden, where district heating is already extensively used, many multiapartment buildings are connected to district heating. For increased use, the distribution systems will have to expand into suburbs with single family homes. However, the environmental impact and cost of the district heat distribution system increase when the pipe networks are extended into such areas. This is due to the production and installation of longer pipe networks and increased heat losses from the system. Attempts have been made to find new types of pipe constructions in order to lower the costs of connecting single family homes to district heating. These should be evaluated from an environmental perspective. The EPSPEX system is a distribution system intended for suburban areas. This system consists of cross-linked polyethylene (PEX) pipes in insulating blocks of expanded polystyrene (EPS). This paper presents a life cycle assessment of the EPSPEX district heat distribution system. In a second scenario, sub-stations were added. The results indicate areas that require improvement and provide a basis for comparison with other types of district heat distribution systems.

Methods

Production, network construction and use of the district heat system were studied by means of life cycle methodology, employing specific data for the EPSPEX system and generic data for upstream impacts of the materials used. The system constructed in Vråen, Värnamo, Sweden, in 2002 was studied. The district heating used in Vråen is mainly based on biofuels. The functional unit was the use of one metre of an EPSPEX district heating system over a period of one year. The expected system life was 30 years. The results were characterised as global warming potential, acidification potential, eutrophication potential and the use of finite resources, as well as weighted by EPS 2000, ExternE and EcoIndicator 99. No external review was performed, but a reference group of district heating experts familiar with the practice has reviewed the study.

Results

Heat losses are clearly the main environmental impact in all characterisations and weightings (71–92% of the total impact), despite the fact that the heat production studied was mainly based on biomass combustion, generally perceived to be environmentally friendly. Of the system components, the production of EPS insulation blocks had the largest environmental impact.

Discussion

This impact, however, is compensated for by the fact that the need to produce less heat leads to a lower level of emissions. Several characterisation methods revealed that the production and combustion of diesel for excavating the pipe trench has a significant environmental impact. The jointing brass swaged coupling used for the PEX fluid pipes has a surprisingly high impact in terms of acidification and EPS 2000, considering the small amount of brass in the system.

Conclusions

The life cycle environmental impact is dominated by the heat production needed to compensate for heat losses from the system, despite the fact that the EPSPEX system is relatively well insulated compared to a conventional district heating system. It is possible to shut down the heating circuit and only use the hot tap water circuit during the summer months; this reduces the heat losses and is an advantageous feature of the system. The second largest environmental impact of the EPSPEX system arises from the production of the EPS insulation blocks. A decrease in nitrogen oxide emissions, especially those caused by the excavation and filling of pipe trenches, would be beneficial. A rough comparison has been made with available literature data for conventional DN25 twin pipes. The results indicate that the environmental impact of the EPSPEX system is probably lower. However, the pipes are not identical, as the water delivery capacity of the conventional pipe is slightly lower.

Recommendations and Perspectives

In Sweden, new types of pipes are being developed for district heating in suburban areas, and there is a need for an environmental comparison between such new alternatives and previous results for conventional polyurethane insulated steel pipes. This study reveals that biofuels, although perceived to be environmentally friendly, must be used with caution in order to ensure a satisfactory environmental performance. Heat loss from district heating should be minimized also when biofuels are used. The most immediate way to reduce such environmental impact is to increase the insulation. The environmental trade-off between lower heat losses achieved by the use of more insulation and the production of greater amounts of insulation material should be further studied.

     

Modeling the distribution of a wide‐ranging invasive species using the sampling efforts of expert and citizen scientists

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