Large Sex Differences Research Articles

Female zebra finches do not sing yet share neural pathways necessary for singing in males.

Adult female zebra finches (Taeniopygia guttata), which do not produce learned songs, have long been thought to possess only vestiges of the forebrain network that supports learned song in males. This view ostensibly explains why females do not sing-many of the neural populations and pathways that make up the male song control network appear rudimentary or even missing in females. For example, classic studies of vocal-premotor cortex (HVC, acronym is name) in male zebra finches identified prominent efferent pathways from HVC to vocal-motor cortex (RA, robust nucleus of the arcopallium) and from HVC to the avian basal ganglia (Area X). In females, by comparison, the efferent targets of HVC were thought to be only partially innervated by HVC axons (RA) or absent (Area X). Here, using a novel visually guided surgical approach to target tracer injections with precision, we mapped the extrinsic connectivity of the adult female HVC. We find that female HVC shows a mostly male-typical pattern of afferent and efferent connectivity, including robust HVC innervation of RA and Area X. As noted by earlier investigators, we find large sex differences in the volume of many regions that control male singing (male > female). However, sex differences in volume were diminished in regions that convey ascending afferent input to HVC. Our findings do not support a vestigial interpretation of the song control network in females. Instead, our findings support the emerging view that the song control network may have an altogether different function in nonsinging females.

Sex Differences in Aerobic Fitness in Top-Class Soccer Referees.

Castagna, C, Bizzini, M, D'Ottavio, S, and Araújo Póvoas, SC. Sex differences in aerobic fitness in top-class soccer referees. J Strength Cond Res 32(11): 3216-3221, 2018-The aim of this study was to assess the aerobic-fitness differences between male and female top-class soccer field referees (FRs). This with the purpose to provide cutoff values useful for training prescription in female FRs. Forty female top-class FRs (age 34.18 ± 3.50 years and 5 ± 3.9 years international refereeing experience) and 52 male FRs (age 38.4 ± 3.3 years and 5 ± 3.5 years international refereeing experience) candidates in the preliminary open list developed by the FIFA Refereeing Department for the 2014 and 2015 World Cup Tournaments, participated in the study. The FRs were tested for aerobic fitness under laboratory conditions with a progressive speed treadmill test until exhaustion. Female FRs showed to possess, on average, lower (large effect) levels of aerobic fitness and performance compared with their male counterparts. The female FRs' V[Combining Dot Above]O2max (48.1 ± 4.4 ml·kg·min) was 7% (large effect) lower than the male FRs (51.9 ml·kg·min). Peak treadmill speed was 11% lower (large effect) in female FRs (16.27 ± 0.94 vs. 14.64 ± 0.96 km·h). The receiver operating characteristic curve analysis enabled cutoff values (47.8 ml·kg·min for V[Combining Dot Above]O2max) that may be used as preliminary cues to guide physiological selection and training prescription in female FRs aiming to officiate male-soccer matches. Only 2.5% of the female FRs showed V[Combining Dot Above]O2max higher than the mean values of male FRs when using the scaled notation (0.68). Female FRs aiming to officiate male competitions should consider training intensities at anaerobic threshold speed (13 km·h, 95% heart rate max) when developing aerobic fitness. Given the very large sex differences in aerobic performance, strength/power training should be proposed to perspective female top-class FRs.

Analysis of Human Brain Structure Reveals that the Brain “Types” Typical of Males Are Also Typical of Females, and Vice Versa

Findings of average differences between females and males in the structure of specific brain regions are often interpreted as indicating that the typical male brain is different from the typical female brain. An alternative interpretation is that the brain types typical of females are also typical of males, and sex differences exist only in the frequency of rare brain types. Here we contrasted the two hypotheses by analyzing the structure of 2176 human brains using three analytical approaches. An anomaly detection analysis showed that brains from females are almost as likely to be classified as “normal male brains,” as brains from males are, and vice versa. Unsupervised clustering algorithms revealed that common brain “types” are similarly common in females and in males and that a male and a female are almost as likely to have the same brain “type” as two females or two males are. Large sex differences were found only in the frequency of some rare brain “types.” Last, supervised clustering algorithms revealed that the brain “type(s)” typical of one sex category in one sample could be typical of the other sex category in another sample. The present findings demonstrate that even when similarity and difference are defined mathematically, ignoring biological or functional relevance, sex category (i.e., whether one is female or male), is not a major predictor of the variability of human brain structure. Rather, the brain types typical of females are also typical of males, and vice versa, and large sex differences are found only in the prevalence of some rare brain types. We discuss the implications of these findings to studies of the structure and function of the human brain.

Infants’ looking times in a dynamic mental rotation task: Clarifying inconsistent results

In adults, the paper-and-pencil Mental Rotation Test (MRT) consistently produces large sex differences favouring men. In contrast, sex effects in response times in the mental rotation task are small or absent. In recent years, a number of studies using different stimuli and experimental approaches investigated sex differences in mental rotation in infants with inconsistent results. The goal of the present study was to examine on the basis of a sufficient statistical power (a) whether infants aged 5–6 (N = 208) or 9–10 months (N = 168) are able to use mental rotation in a habituation task with complex and dynamic 3D cube figures rotated in depth; (b) whether there were sex differences present, (c) whether looking times at 5–6 months can predict looking times at 9–10 months, and finally, (d) whether 9-month-olds’ looking times during mental rotation depend upon their crawling ability.Our data suggest that the habituation paradigm is suited to reveal mental rotation in 5- to 6-month-old infants (although the effects are small) but not in older ones. Moreover, we obtained no evidence for sex differences, we found no stability of looking times across infancy, and obtained no evidence suggesting an effect of crawling experience on mental rotation ability. More studies based on sufficiently large sample sizes are needed to evaluate mental rotation and possible sex differences in infancy.

Development and predictors of mental ill-health and wellbeing from childhood to adolescence.

The aim is to investigate the (1) longitudinal development in mental ill-health and wellbeing from ages 11 to 14, (2) predictors of changes in mental health outcomes, and (3) sex and reporter differences. Data are taken from 9553 participants in the Millennium Cohort Study, with both mental ill-health (parent- and self-report) and wellbeing outcomes of the cohort members measured at ages 11 and 14. A range of childhood socio-demographic, human capital, family and wider environment risk and protective factors are investigated. Wellbeing has weak stability and mental ill-health has moderate stability between ages 11 and 14 and large sex differences emerge in all the mental health outcomes investigated, with girls experiencing lower wellbeing and greater symptoms of mental illness at age 14. Raw associations between outcomes, and differences in their predictors, indicate varying patterns emerging for parent- and self-reported mental ill-health, with parent-reported symptoms in childhood a poor predictor of both self-reported wellbeing and depressive symptoms in adolescence. Investigating the emergent sex differences in prevalences highlights childhood risk and protective factors at this age that are more salient in females, including family income, school connectedness, cognitive ability, whereas peer relationships and bullying were equally relevant for mental health development in both males and females. Low-moderate stability of mental health outcomes stresses the importance of the transition period for mental health, highlighting an intervention window at these ages for prevention. Socio-economic status is associated with mental health development in females but not in males at this age, highlighting a sex-specific vulnerability of deprivation associated with poorer mental health in adolescent females.

Sex differences in romantic attachment among Chinese: A meta-analysis

Although several studies support evolutionary perspectives on sex differences in romantic attachment, these sex differences in East Asia remain controversial. To estimate the effect size of sex differences in romantic attachment among Chinese adults, a meta-analysis of sex differences was conducted in the present study. This meta-analysis was based on 111 samples using the Chinese version of the Experiences in Close Relationships Scale and its revised version. The findings suggest that the effect size of sex differences in romantic attachment among Chinese adults is relatively small. Overall, females demonstrated higher anxiety and avoidance than males, with substantial between-study heterogeneity. Sex differences were largest in community samples, with higher avoidance and lower anxiety in males. There were smaller sex differences in college student samples, with higher anxiety and avoidance in females. The degree of sex differences also varied across geographical regions, with high-stress and high-fertility reproductive environments showing smaller sex differences in general and larger sex differences in extreme conditions. Sex differences in anxiety increased linearly with age, whereas those in avoidance remained unchanged. The results support evolutionary perspectives of sex differences in romantic attachment, which assume that the average sex differences in romantic attachment styles should be relatively small in most populations, and many possible factors might moderate such differences. The heterogeneity and limitations of the current findings and directions for future research on sex differences in romantic attachment are discussed.

Liver cancer mortality trends in South Africa: 1999\u20132015

BackgroundIn South Africa (SA), liver cancer (LC) is a public health problem and information is limited.MethodsJoinpoint regression analysis was computed for the most recent LC mortality data from Statistics South Africa (StatsSA), by age group, sex and population group. The mortality-to-incidence ratios (MIRs) were calculated as the age-adjusted mortality rate divided by the age-adjusted incidence rate.ResultsFrom 1999 to 2015, the overall LC mortality significantly decreased in men (− 4.9%) and women (− 2.7%). Overall a significant decrease was noted in black African men aged 20–29 and 40–49 years, and white women older than 60 years but mortality rates increased among 50–59 and 60–69 year old black African men (from 2010/2009–2015) and women (from 2004/2009–2015). The mortality rates increased with age, and were higher among blacks Africans compared to whites in all age groups - with a peak black African-to-white mortality rate ratio of six in men and three in women at ages 30–39 years. The average MIR for black African men and women was 4 and 3.3 respectively, and 2.2 and 1.8 in their white counterparts. Moreover, decreasing LC mortality rates among younger and the increase in rates in older black Africans suggest that the nadir of the disease may be near or may have passed.ConclusionsFindings of population-age subgroup variations in LC mortality and the number of underdiagnosed cases can inform surveillance efforts, while more extensive investigations of the aetiological risk factors are needed. Impact: There was a large race, sex and age differences in trends of LC mortality in SA. These findings should inform more extensive evaluation of the aetiology and risk factors of LC in the country in order to guide control efforts.

Looking behind the score: Skill structure explains sex differences in skilled video game performance.

Some have explained large sex differences in visuospatial abilities by genetic adaptations to different roles in primitive hunter-gatherer societies and the interaction of innate biological differences and environmental factors. We explored the extent to which variations in behavior and acquired skills can provide alternative accounts for sex differences in the performance of a complex spatially-demanding video game (Space Fortress). Men and women with limited video game experience were given 30 hours of training, and latent curve analyses examined the development of their ship control performance and behavior. Men had significantly better control performance than women before and after training, but differences diminished substantially over the training period. An analysis of participants’ joystick behaviors revealed that initially men and women relied on different patterns of control behaviors, but changes in these behaviors over time accounted for the reduced sex differences in performance. When we controlled for these differences in behavior, sex effects after training were no longer significant. Finally, examining the development of control performance and control behaviors of men and women categorized as initially high and low performers revealed the lower-performing women may have been controlling their ship using an approach that was very different from the men and higher-performing women. The potential problems of analyzing men and women’s spatial performance as homogenous groups are discussed, as well as how these issues may account for sex differences in skilled video game performance and perhaps other domains involving spatial abilities.

Development of sex differences in math achievement, self-concept, and interest from grade 5 to 7

Sex differences in mathematics achievement have been a controversial topic in educational psychology for a long time. This study sheds light on the developmental aspects of sex differences in math achievement and domain-specific motivational variables such as self-concept and interest. Using a Reciprocal Effects Model (REM), we analyzed 2,342 German fifth to seventh grade students who participated in a large-scale longitudinal study. Math self-concept was validated as a consistent predictor of subsequent achievement and interest for both sexes, supporting the self-enhancement part of the REM using test-scores and teacher-assigned grades. However, math achievement affects subsequent self-concept inconsistently (i.e., the skill development part). Although the bivariate relationships between the constructs were homogeneous across sex and over time, there were large sex differences in the motivational constructs, but not in the achievement measure regardless of achievement measures. The present findings underline the importance of considering both the mean and the covariance structure when describing sex differences in academic achievement. In addition, they also stress the impact of motivational constructs on educational achievement, which also have implications for sex-specific intervention programs in general.

The effect of aging on pacing strategies of cross-country skiers and the role of performance level

BackgroundThe participation of master cross-country (XC) skiers in training and competition has increased during the last decades; however, little is known yet about whether these athletes differ from their younger counterparts in aspects of performance such as pacing. Therefore, the aim of the present study was to examine the combined effect of age and performance (race time) on pacing in cross-country (XC) skiing. We analyzed all finishers (n = 79,722) in ‘Vasaloppet’ from 2012 to 2017, the largest cross-country skiing race in the world, classified according to their race time into 10 groups: 3-4 h, 4-5 h, ..., 12-13 h.ResultsA trivial main effect of sex on total pace range was observed (p < 0.001, η2 = 0.002), where women (44.1 ± 10.2%) had larger total pace range than men (40.9 ± 11.8%). A large main effect of performance group on total pace range was shown (p < 0.001, η2 = 0.160), where the smallest total pace range was 21.8 ± 1.9% (3-4 h group) and the largest 50.1 ± 9.9% (10-11 h group). A trivial sex×performance group interaction on total pace range was found (p < 0.001, η2 = 0.001) with the largest sex difference in pacing shown in 9-10 h group. A trivial and small main effect of age was found in women (p < 0.001, η2 = 0.005) and men (p < 0.001, η2 = 0.011), respectively, where the masters had smaller total pace range than their younger counterparts. A trivial age group×performance group interaction on total pace range was observed in both women (p < 0.001, η2 = 0.008) and men (p < 0.001, η2 = 0.006) with smaller differences among age groups in the faster performance groups.ConclusionsIn summary, master XC skiers adopted a relatively even pacing independently from their race time and the differences in pacing from the younger XC skiers were more pronounced in the slower masters. These findings suggest that exercise attenuates the decline of performance in master XC skiers as shown by the similar pacing strategies between fast master XC skiers and their younger counterparts.

Is oxidative stress involved in the sex-dependent response to ochratoxin A renal toxicity?

Ochratoxin A (OTA) is a mycotoxin considered the most powerful renal carcinogen in rodents and classified as a possible human carcinogen. Though its mechanism of action is still unknown, indirect DNA reactivity mediated by oxidative stress has been hypothesized to play an important role. Moreover, large sex-differences have been observed in carcinogenicity studies, male rats being more sensitive than females. Male and female F344 rats were administered (p.o.) with bicarbonate or 0.5 mg OTA/kg b.w. for 7 days; or with bicarbonate, 0.21 or 0.5 mg OTA/kg b.w. for 21 days. Total glutathione (tGSH) and oxidized glutathione (GSSG) levels, glutathione S-transferase (GST) and superoxide dismutase (SOD) activities were analysed in kidneys. The standard alkaline comet assay was used in combination with Formamidopyrimidine-DNA glycosylase (Fpg) to detect oxidized DNA bases in kidney. No biologically relevant sex-differences were observed in all the oxidative-stress related parameters analysed. Indeed, no relevant oxidative-stress related response was observed between treated animals and controls. In accordance with the similar OTA levels and histopathological changes between both sexes observed previously in the same animals, and with other oxidative-stress related parameters measured by others, results support that there are no differences between sexes in the oxidative stress response to OTA.

Cosmetic Surgery in Iran: Sociodemographic Characteristics of Cosmetic Surgery Patients in a Large Clinical Sample in Tehran

Sociodemographic characteristics of cosmetic surgery patients are less studied in developing countries. Examining sociodemographic characteristics of cosmetic surgery patients in clinical settings can help surgeons identify their potential patients and highlights marketing opportunities for medical institutions. We conducted this study to determine the sociodemographic details of a large clinical sample from Tehran, Iran. The aim of this study was to present the demographic characteristics of Iranian patients undergoing cosmetic procedures. Tehran was selected from Iran as its most populated city and center of most medical facilities. The present study aimed to examine the sociodemographic characteristics of a large clinical sample (N = 744 patients; 900 cosmetic procedures) who underwent cosmetic surgery in Tehran, Iran. These surgeries were performed by 3 well-known plastic surgeons in Tehran. Sociodemographic details were gathered using patient’s cases and phone interview. A previously published questionnaire with modification was used. Findings suggest that most of the patients (90.7%) are women. Rhinoplasty (61.3%), facial fat injection (6.7%), blepharoplasty (6.3%), facelift (4.0%), and breast augmentation (3.8%) were the top 5 cosmetic procedures in the present sample. Approximately half of the sample (49.6%) was single, and most of married patients (80%) had children. A large number of patients (37.2%) were between 30 and 39 years old. In addition, a considerable proportion of the sample reported university education and being currently employed. This is the first study to document sociodemographic details in a large clinical sample from Iran as an understudied setting. We used insights from evolutionary psychology to explain the large sex differences in the number of cosmetic surgeries. In addition, we compared the findings with existing evidence from the United States and Saudi Arabia. Limitations and future directions are also discussed.

What factors may contribute to sex differences in childhood obesity prevalence in China?

Previous studies in China showed large sex differences in childhood overweight and obesity (OW/OB) rates. However, limited research has examined the cause of these sex differences. The present study aimed to examine individual and parental/familial factors associated with sex differences in childhood OW/OB rates in China. Variables associated with child weight status, beliefs and behaviours, and obesity-related parenting practices were selected to examine their sex differences and association with a sex difference in child OW/OB outcomes using logistic regression analysis. Cross-sectional data analysis using the 2011 China Health and Nutrition Survey. Children aged 6-17 years (n 1544) and their parents. Overall child OW/OB prevalence was 16·8 %. Adolescent boys (AB; 12-17 years) were about twice as likely to be overweight/obese as adolescent girls (AG; 15·5 v. 8·4 %, P<0·05). AB more likely had energy intake exceeding recommendations, self-perceived underweight, underestimated their body weight and were satisfied with their physical activity level than AG. AG more likely practised weight-loss management through diet and self-perceived overweight than AB. Mothers more likely identified AG's weight accurately but underestimated AB's weight. Stronger associations with risk of childhood OW/OB were found in boys than girls in dieting to lose weight (OR=6·7 in boys v. 2·6 in girls) and combined maternal and child perception of the child's overweight (OR=35·4 in boys v. 14·2 in girls). Large sex differences in childhood obesity may be related to the sex disparities in weight-related beliefs and behaviours among children and their parents in China.

Heterosexual male and female disparities in HIV infection at the end of an epidemic: HIV infection among persons who inject drugs in New York City, 2001–2005 and 2011–2015

BackgroundWe examined whether sex disparities (heterosexual male:female) in HIV infection continue to persist at the “end of the HIV epidemic” among persons who inject drugs (PWID) in New York City (NYC). An “end of the epidemic” was operationally defined as 1) prevalence of untreated HIV infection <5%, and 2) estimated HIV incidence <0.5/100 person-years. MethodsPWID were recruited from persons entering substance use treatment programs at Mount Sinai Beth Israel in 2001–2005 and 2011–2015. A structured interview was administered, and HIV and HSV-2 testing was conducted. Incidence was estimated using newly diagnosed cases of HIV. Disparity analyses compared prevalence of HIV, of untreated HIV, HIV risk behaviors, and estimated HIV incidence. ResultsBy 2011–2015, both heterosexual male and female PWID met the two criteria for an “end of the epidemic,” and there were no significant differences in the prevalence of untreated HIV infection. A large sex difference remained in estimated HIV incidence. In 2013–2015, estimated HIV incidence was 2.8/10,000 PY for males and 7.1/10,000 PY for females. Females had greater risk for HIV on several factors. ConclusionWhile NYC has reached an “end of the epidemic” for both heterosexual male and female PWID, sex disparities persist, particularly differences in HIV incidence. Eliminating the sex disparities may require a greater focus on factors associated with sexual transmission.

Mothers, fathers, sons, and daughters: Are there sex differences in the organization of secure base behavior during early childhood

Recent empirical studies reporting sex differences in attachment relationships have prompted investigators to consider why and under what conditions such results might be observed. This study was designed to explore possibilities of identifying sex differences in the organization of attachment-relevant behavior during early childhood. Observations of 119 children (59 boys) with their mothers and (separately) with their fathers were completed and children were described using the AQS. Results indicated that girls and boys did not differ with respect to global attachment security but at more specific level analyses revealed differences between parents that reflected differences in the behaviors of girls vs. boys with mothers and fathers. Our findings contradict arguments from evolutionary psychologists claiming that sex differences in attachment organization arise during middle childhood. By adopting an attachment measure sensitive to the possibility of behavioral sex differences our data suggest that such differences may be detectable earlier in development. Moreover, these differences are subtle and nuanced and do not suggest large sex differences in attachment security per se.

Effects of Age and Sex on Hospital Readmission in Traumatic Brain Injury

ObjectiveTo investigate the effects of age and sex on 30-, 60-, and 90-day hospital readmission after acute hospital discharge for individuals with traumatic brain injury (TBI). DesignRetrospective cohort study. SettingAcute hospitals and postacute discharge settings. ParticipantsIndividuals (N=52,877) with Diagnosis Related Group codes of TBI, who were divided into 4 age groups: 18 to 40, 41 to 65, 66 to 75, and ≥76 years. InterventionsNot applicable. Main Outcome MeasuresAll-cause hospital readmission. ResultsSex differences in 30-, 60-, and 90-day hospital readmission were found among all age groups (P<.05 for all). The largest sex differences in hospital readmission were in the 2 oldest groups (66–75 and ≥76y). For both sexes, the oldest group (≥76y) had the highest adjusted 90-day readmission risk (eg, 90-d readmission: odds ratio, 2.32 [95% confidence interval, 2.01–2.69] for men; odds ratio, 1.96 [95% confidence interval, 1.59–2.43] for women). Among those readmitted within 90 days, the youngest group (18–40y) had the highest cumulative readmission percentage (35% for both sexes) within the first week of hospital discharge. ConclusionsAge and sex were significantly associated with hospital readmission during the first 90 days postdischarge in our TBI sample. Specifically, those aged 66 to 75 or ≥76 years had the highest readmission risk over 90 days for both sexes. The findings suggest that clinicians should consider age and sex in discharge planning and for the entire episode of care for the population with TBI.

Sex Differences in World-Record Performance: The Influence of Sport Discipline and Competition Duration.

The current review summarizes scientific knowledge concerning sex differences in world-record performance and the influence of sport discipline and competition duration. In addition, the way that physiological factors relate to sex dimorphism is discussed. While cultural factors played a major role in the rapid improvement of performance of women relative to men up until the 1990s, sex differences between the world's best athletes in most events have remained relatively stable at approximately 8-12%. The exceptions are events in which upper-body power is a major contributor, where this difference is more than 12%, and ultraendurance swimming, where the gap is now less than 5%. The physiological advantages in men include a larger body size with more skeletal-muscle mass, a lower percentage of body fat, and greater maximal delivery of anaerobic and aerobic energy. The greater strength and anaerobic capacity in men normally disappear when normalized for fat-free body mass, whereas the higher hemoglobin concentrations lead to 5-10% greater maximal oxygen uptake in men with such normalization. The higher percentage of muscle mass in the upper body of men results in a particularly large sex difference in power production during upper-body exercise. While the exercise efficiency of men and women is usually similar, women have a better capacity to metabolize fat and demonstrate better hydrodynamics and more even pacing, which may be advantageous, in particular during long-lasting swimming competitions.

Adults’ Sex Difference in a Dynamic Mental Rotation Task

Abstract. With the Mental Rotation Test (MRT), large and reliable sex differences are found. Used with children younger than about 9 or 10 years, MRT performance is at chance level. Simpler tasks used with younger children have revealed inconclusive results. Moore and Johnson (2008 , 2011 ) observed sex differences in infants using a habituation task with 3D cube figures rotating back and forth in depth through a 240° angle. Thereafter, female infants treated similarly the original figure and a mirror-image cube figure presented revolving through the previously unseen 120° angle, whereas male infants behaved as if they recognized the familiar object. In the present study, 256 adults participated in the MRT as well as in a modified two-alternative forced-choice dynamic version of the infants’ task. Sex differences were present for both tasks. More importantly, there was a positive correlation in performance across both tasks for both women and men. Since the new task turned out to be simpler, it might be suitable also for children. We present the first, although indirect, evidence that the sex effects reported by Moore and Johnson might indeed reflect early sex differences in mental rotation.

Relationship between Voided Urine Volume and Urinary ATP in Healthy Volunteers

Purpose: We examined the relationship between the urinary ATP level and the desire to void, voided urine volume, and urinary osmotic pressure. Materials and Methods: The subjects were 4 healthy volunteers (2 men and 2 women) without micturition disorders who were not taking any medications and had normal urinalysis findings. Over 2 - 3 days, they urinated into a clean cup a total of 20 times. The strength of the desire to void was classified (none, slight, moderate, or strong; scored from 1 to 4, respectively) and a voiding score was assigned at each urination, along with measurement of the voided volume, urinary ATP, urinary creatinine, and urinary osmotic pressure (one man). Results: Variation of the urinary ATP/creatinine ratio was large in both male and female subjects. The urinary ATP/creatinine ratio was lower in the 2 men compared with the 2 women. This ratio showed a significant negative correlation (R2 = 0.1577 and 0.1673, both p < 0.05) with the voided urine volume in the male subjects. However, there was no relationship between the urinary ATP/creatinine ratio and the voiding score or voided urine volume in the female subjects. Conclusions: The urinary ATP level may not be a clinically useful marker of bladder pathology. Both the present study and our previous studies identified a large sex difference in the urinary ATP/creatinine ratio, and this finding may be important when considering the causes of overactive bladder (OAB) in women. The mechanism underlying the increase in urinary ATP in women should be investigated to develop new therapies for OAB.

Temporal relationships between food acquisition and voluntary exercise in mice

Patterns of operant food acquisition in a closed economy and bouts of either voluntary wheel running (WR) or spontaneous locomotor activity in a standard condition (SC) with no wheel were examined in young adult male and female C57BL/6 mice across a range of nose poke prices (FUP) per food pellet. Both sexes showed vigorous WR or locomotor activity. At each FUP, WR groups had higher food intake than SC groups. Despite substantially higher mean body weight of males compared with females, intakes and activity did not differ by sex in the SC groups and males lost weight more rapidly as FUP increased. In contrast, WR males ran ∼33% further per day than females, increased their food intake (above that of SC counterparts) more than females, and lost less body weight than SC males. By parsing the night in four 3h epochs it was found that food intake declined progressively through the night in both WR and SC mice and that the hyperphagia of WR relative to SC groups was most evident early in the night, coincident with highest activity. No large or systematic sex differences were revealed in these temporal analyses. Analysis of data at 60s resolution showed that pellet acquisition occurred in many small or short bouts, the timing of which was either intercalated or concurrent with either locomotor activity or WR. The results show that increased eating due to WR occurs concurrently with maximum running, and with no evidence of delayed compensation.