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Sex matters in the establishment of murine tendon composition and material properties during growth.

ABSTRACT: The existence of sex-based differences in tendon and ligament injury rates has led investigators to test the hypothesis that sex plays a significant role in modulating tendon and ligament composition and material properties. To date, no studies have attempted to characterize how such differences develop during the course of normal tissue maturation and growth. Thus, the primary aim of the present study was to use a murine model to test the hypothesis that sex-based differences in the normal age-related development of tendon composition and material properties exist by assessing these parameters in the Achilles and tail tendons from 4-, 6-, 9-, 12-, and 15-week-old male and female C57Bl/6J mice. Despite significantly lower levels of total collagen content in females subsequent to sexual maturity (p<0.0001), as well as a significant effect of sex on glycosaminoglycan content (p<0.0001), Achilles tendon elastic modulus was not compromised in females. Female Achilles tendons did exhibit a significantly higher failure strain (p=0.0201) and strain energy density (p=0.0004) than did males, as well as a trend toward higher ultimate strength (p=0.0556). In contrast to the high load-bearing environment of the Achilles tendon site, sex did not have a statistically significant effect on any compositional or material property in the low load-bearing tendon fascicles of the tail. These data support recent studies by others, which suggest that male and female tendons have a differential adaptational response to their local mechanical loading environment.

SUBMITTER: Mikic B

PROVIDER: S-EPMC2845721 | biostudies-literature | 2010 May

REPOSITORIES: biostudies-literature

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Sex matters in the establishment of murine tendon composition and material properties during growth.

Mikic Borjana B Amadei Elizabeth E Rossmeier Kerri K Bierwert LouAnn L

Journal of orthopaedic research : official publication of the Orthopaedic Research Society 20100501 5

The existence of sex-based differences in tendon and ligament injury rates has led investigators to test the hypothesis that sex plays a significant role in modulating tendon and ligament composition and material properties. To date, no studies have attempted to characterize how such differences develop during the course of normal tissue maturation and growth. Thus, the primary aim of the present study was to use a murine model to test the hypothesis that sex-based differences in the normal age- ...[more]

PMID: 19950332

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Project description:BackgroundAutistic individuals frequently experience social communication challenges. Girls are diagnosed with autism less often than boys even when their symptoms are equally severe, which may be due to insufficient understanding of the way autism manifests in girls. Differences in the behavioral presentation of autism, including how people talk about social topics, could contribute to these persistent problems with identification. Despite a growing body of research suggesting that autistic girls and boys present distinct symptom profiles in a variety of domains, including social attention, friendships, social motivation, and language, differences in the way that autistic boys and girls communicate verbally are not yet well understood. Closely analyzing boys' and girls' socially-focused language during semi-structured clinical assessments could shed light on potential sex differences in the behavioral presentation of autistic individuals that may prove useful for identifying and effectively supporting autistic girls. Here, we compare social word use in verbally fluent autistic girls and boys during the interview sections of the ADOS-2 Module 3 and measure associations with clinical phenotype.MethodsSchool-aged girls and boys with autism (N = 101, 25 females; aged 6-15) were matched on age, IQ, and parent/clinician ratings of autism symptom severity. Our primary analysis compared the number of social words produced by autistic boys and girls (normalized to account for differences in total word production). Social words are words that make reference to other people, including friends and family.ResultsThere was a significant main effect of sex on social word production, such that autistic girls used more social words than autistic boys. To identify the specific types of words driving this effect, additional subcategories of friend and family words were analyzed. There was a significant effect of sex on friend words, with girls using significantly more friend words than boys. However, there was no significant main effect of sex on family words, suggesting that sex differences in social word production may be driven by girls talking more about friends compared to boys, not family. To assess relationships between word use and clinical phenotype, we modeled ADOS-2 Social Affect (SA) scores as a function of social word production. In the overall sample, social word use correlated significantly with ADOS-2 SA scores, indicating that participants who used more social words were rated as less socially impaired by clinicians. However, when examined in each sex separately, this result only held for boys.LimitationsThis study cannot speak to the ways in which social word use may differ for younger children, adults, or individuals who are not verbally fluent; in addition, there were more autistic boys than girls in our sample, making it difficult to detect small effects.ConclusionsAutistic girls used significantly more social words than boys during a diagnostic assessment-despite being matched on age, IQ, and both parent- and clinician-rated autism symptom severity. Sex differences in linguistic markers of social phenotype in autism are especially important in light of the late or missed diagnoses that disproportionately affect autistic girls. Specifically, heightened talk about social topics could complicate autism referral and diagnosis when non-clinician observers expect a male-typical pattern of reduced social focus, which autistic girls may not always exhibit.

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Sex matters in the establishment of murine tendon composition and material properties during growth.

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Sex matters in the establishment of murine tendon composition and material properties during growth.

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