Fatty acids as trophic biomarkers in vitellogenic females in an impounded tropical river

Fatty acids have been used in marine biogeochemistry as food chain biomarkers, but in freshwater these studies are rare. In order to evaluate the fatty acid potential as biomarkers in freshwater, their profile was analyzed during vitellogenesis in two fish species, in both waterfall and reservoir environments of the Paraiba do Sul River Basin. Detrivorous Hypostomus affinis and omnivorous Geophagus brasiliensis seem to elongate and desaturate polyunsaturated fatty acids (PUFA) and transfer them to the ovaries` phospholipids. Waterfall Geophagus brasiliensis have more highly unsaturated fatty acids in the liver, but in the reservoir, accumulation mainly occurs in muscle and ovary triglycerides, suggesting trophic opportunism and a plasticity during vitellogenesis. In Hypostomus affinis, PUFA alteration occurs only in the reservoir, suggesting a high phytoplankton occurrence. Eutrophication and water speed is reflected in Hypostomus affinis ovaries by higher PUFAn3 and bacterial fatty acids. As in marine environments, analysis of mono- and polyunsaturated fatty acids during vitellogenesis can be used as a tool in food chain studies in freshwater.

Carbohydrate metabolism during exercise in females : effect of reduced fat availability

This study examined the effect of reduced plasma free fatty acid (FFA) availability on carbohydrate metabolism during exercise. Six untrained women cycled for 60 minutes at approximately 58% of maximum oxygen uptake after ingestion of a placebo (CON) or nicotinic acid (NA), 30 minutes before exercise (7.4 ± 0.5 mg·kg⁻¹ body weight), and at 0 minutes (3.7 ± 0.3 mg·kg⁻¹) and 30 minutes (3.7 ± 0.3 mg·kg⁻¹) of exercise. Glucose kinetics were measured using a primed, continuous infusion of [6,6-²H] glucose. Plasma FFA (CON, 0.86 ± 0.12; NA, 0.21 ± 0.11 mmol·L⁻¹ at 60 minutes, P < .05) and glycerol (CON, 0.34 ± 0.05; NA, 0.10 ± 0.04 mmol·L⁻¹ at 60 minutes, P < .05) were suppressed throughout exercise. Mean respiratory exchange ratio (RER) during exercise was higher (P < .05) in NA (0.89 ± 0.02) than CON (0.83 ± 0.02). Plasma glucose and glucose production were similar between trials. Total glucose uptake during exercise was greater (P < .05) in NA (1,876 ± 161 μmol·kg⁻¹) than in CON (1,525 ± 107 μmol·kg⁻¹). Total fat oxidation was reduced (P < .05) by approximately 32% during exercise in NA. Total carbohydrate oxidized was approximately 42% greater (P < .05) in NA (412 ± 40 mmol) than CON (290 ± 37 mmol), of which, approximately 16% (20 ± 10 mmol) could be attributed to glucose. Plasma insulin and glucagon were similar between trials. Catecholamines were higher (P < .05) during exercise in NA. In summary, during prolonged moderate exercise in untrained women, reduced FFA availability results in a compensatory increase in carbohydrate oxidation, which appears to be due predominantly to an increase in glycogen utilization, although there was a small, but significant, increase in whole body glucose uptake.

Body image ideal among males and females: sociocultural influences and focus on different body parts

Past research has obtained mixed findings in relation to gender differences and other factors that shape ideal body image. The current study was designed to investigate these differences further, using a digital body image program to assess body image individually. As expected, females desired a body that was smaller than their current size, whereas males were split between wanting a smaller and larger body. The perceived messages from peers and parents were consistent with the individual's ideal image. Gender differences were also found with ratings of attractiveness and effectiveness. Females rated messages from peers and parents as more important than did males. For both males and females, opposite sex peers were the most important influences, and parents the least important.

Human skeletal muscle creatine transporter mRNA and protein expression in healthy, young males and females

The present study investigated whether there were any differences between males and females in respect to creatine transporter (CreaT) gene expression and/or total creatine (TCr) content in human vastus lateralis muscle. Skeletal muscle obtained from young healthy male (n = 13, age: 23.2 ± 5.0 years) and female subjects (n = 12, age: 21.7 ± 4.3 years) was analyzed for CreaT mRNA, CreaT protein and TCr content. Total CreaT protein content in the muscle was similar (p > 0.05) between the sexes. Two bands (~ 55 and 73 kDa) of the CreaT protein were detected in all muscle samples. Both the 55 and the 73 kDa bands were present in similar (p > 0.05) amounts in males compared with females. The 73 kDa band was in greater abundance (p < 0.05) than the 55 kDa band, irrespective of gender. In addition, CreaT mRNA expression relative to ß-actin mRNA and the TCr content (males: 117.8 ± 2.2, females: 125.3 ± 4.3 mmol.kg^–1 dry mass) were also unaffected (p > 0.05) by gender. These data demonstrate that gender does not influence skeletal muscle TCr content and CreaT gene expression in young human subjects.

On the borders of sexuality research: young people who have sex with both males and females

As D' Augelli and Grossman point out, there is an underrepresentation in LGB research of "youth who have had sexual experiences with both males and females." Indeed, Heath (2005) refers to the "silent B" in much GLBT research. And, Owens (1998, p. 55) discusses how heterosexism "formalizes a societal dichotomy of heterosexuality versus homosexuality with little room for bisexuals" in educational research. Most of the information on bisexuality has been obtained from studies with adult samples, and it is "unclear to what extent a separate bisexual cultural identity is consolidated during adolescence" (Ryan & Rivers, 2003, p.105). As Bryan, a 17-year-old bisexual young man in my research, declared: "It's simple bullshit logic! They don't have evidence of bi kids in schools because they don't want to find it and so don't write their research looking for it."

The effect of mood on opposite-sex judgments of males' commitment and females sexual intent

Gender differences in perceptions of sexual intent and commitment have been the subject of formal and informal inquiry for considerable time. One evolutionary theory, Error Management Theory (EMT), predicts that opposite-sex perceptions of female sexual intent and male commitment intent reflect intrinsic biases that minimize gender-specific evolutionary costs. The results supporting these hypotheses were obtained from subjects regardless of mood. We hypothesized that mood would influence ratings of sexual and commitment intent. Sixty participants (30 males, 30 females) were recruited and exposed to a positive and negative mood condition in counterbalanced groups using video stimuli. Preliminary analyses found an unexpected effect of order of mood induction, necessitating separate analyses of the Positive-Negative (PN) and Negative-Positive (NP) groups. Contrary to the original study, there were no gender effects. Positive moods led to increased ratings of both sexual and commitment intent across genders. Further, negative to positive mood-change was associated with significantly increased ratings. Both males and females attributed significantly higher sexual intent to same-sex rivals than themselves, but only males assessed themselves as having significantly higher commitment intent than same-sex rivals. The EMT model may require adaptation to acknowledge effects of variables such as mood on its predictions of gender-specific biases.

Does gymnastics training inhibit growth of females?

OBJECTIVE: The increasingly dominant performance of smaller-sized female gymnasts and increased magnitude of training beginning at an early age have prompted public and medical concerns, especially from an auxological perspective. The objective of this review is to determine if gymnastics training inhibits growth of females. DATA SOURCES: An extensive research of MedLine (PubMed interface) along with cross-referencing was conducted using the Text and MeSH words "gymnastics" in combination with "growth," "maturation," "body height," "body weight," and "growth plate." Our analysis is limited to English articles only.
STUDY SELECTION: All published studies that included data related to the research questions were included. MAIN RESULTS: Although data from three historical cohort studies indicate that female gymnasts are short even before they begin training, clinical reports and cohort studies do suggest that some female gymnasts experience attenuated growth during training followed by catch-up growth during periods of reduced training or retirement. There is conflicting evidence whether the "catch-up" is complete. There were no studies reporting prevalence or incidence of inadequate growth. Three cohort studies provide evidence of reduced growth but training was not partitioned from other confounding factors in the gymnastics environment. Although there is a paucity of studies examining the link of dietary practices with diminished growth in female gymnasts, a review of related dietary literature indicates the potential for insufficient energy and nutrient intake among female gymnasts.
CONCLUSIONS: Elite level or heavily involved female gymnasts may experience attenuated growth during their years of training and competition followed by catch-up growth during reduced training schedules or the months following retirement. However, a cause-effect relation between gymnastics training and inadequate growth of females has not been demonstrated.

The effect of calcium supplementation on bone density in premenarcheal females: a co-twin approach

The age and developmental stage at which calcium supplementation produces the greatest bone effects remain controversial. We tested the hypothesis that calcium supplementation may improve bone accrual in premenarcheal females. Fifty-one pairs of premenarcheal female twins (27 monozygotic and 24 dizygotic; mean ± SD age, 10.3 ± 1.5 yr) participated in a randomized, single-blind, placebo-controlled trial with one twin of each pair receiving a 1200-mg calcium carbonate (Caltrate) supplement. Areal bone mineral density (aBMD) was measured at baseline and 6, 12, 18 and 24 months. There were no within-pair differences in height, weight, or calcium intake at baseline. Calcium supplementation was associated (P < 0.05) with increased aBMD compared with placebo, adjusted for age, height, and weight at the following time points from baseline: total hip, 6 months (1.9%), 12 months (1.6%), and 18 months (2.4%); lumbar spine, 12 months (1.0%); femoral neck, 6 months (1.9%). Adjusted total body bone mineral content was higher in the calcium group at 6 months (2.0%), 12 months (2.5%), 18 months (4.6%), and 24 months (3.7%), respectively (all P < 0.001). Calcium supplementation was effective in increasing aBMD at regional sites over the first 12–18 months, but these gains were not maintained to 24 months.

Short-term changes in endogenous estrogen levels and consumption of soy isoflavones affect working and verbal memory in young adult females

Estrogen is known to modulate certain cognitive functions, most notably improving working memory and verbal memory. Soy foods contain isoflavones, phytoestrogens structurally similar to estrogen that weakly bind to estrogen receptors.We investigated the effects of natural variations in estrogen levels and short-term dietary supplementation with soy isoflavones on cognitive function in 28 young women. Performance was examined across a range of cognitive tasks on three occasions during separate menstrual cycles: during a menses phase (low estrogen), during a luteal phase (highest estrogen), and once during a menses phase after a 3-day phytoestrogen-rich dietary intervention. Soy supplementation during menses led to an improvement in working memory and verbal memory. The menstrual cycle effects were mixed, with high estrogen improving performance on a verbal memory task but not on working memory. Our results suggest that soy phytoestrogens may improve working memory through estrogen-independent mechanisms.

Body image and body change strategies among adolescent males and females from Fiji, Tonga and Australia

The current study was designed to investigate the body image and body change strategies of adolescents from Fiji, Tonga and Australia. Participants were 628 Fijians, 463 Indo-Fijians, 598 Tongans and 535 European Australians. Adolescents completed measures of height, weight, body dissatisfaction, strategies to lose weight, increase weight and increase muscles. The results demonstrated that overweight adolescents were more dissatisfied with their bodies than those who were normal weight. Overweight Fijians and Tongans were more satisfied with their body than Indo-Fijian or Australian adolescents. Tongans, followed by Fijians and Indo-Fijians, were more likely to engage in strategies to lose weight, increase weight and increase muscles. These results are consistent with the focus in Fiji and Tonga on the value of the large body ideal, but may also reflect the recent focus on the attainment of a healthy body size.