Masticatory loading and soft-tissue plasticity in the mammalian circumorbital region

Abstract only availableMasticatory loading is the key to understanding the plasticity or epigenetic responses of many of the soft and hard tissues of the mammalian skull. Diet-induced variation in the magnitude and/or frequency of masticatory loads influences the organization, functional adaptation and postnatal development of craniofacial systems. While experimental work exists concerning masticatory stress as a determinant of maxillomandibular form, similar research concerning the mammalian circumorbital region of soft-tissue structures remains sparse. Indeed, controversy remains over the function of the circumorbital region, specifically whether the postorbital region in primates and other mammals is responsive to biomechanical loading. This hinders our understanding of evolutionary transformations during primate origins, where the earliest primates evolved a bony postorbital bar from an ancestor with a soft-tissue structure along the lateral orbital margin. To fill this gap, we examined the postorbital microanatomy of white rabbits (Oryctolagus cuniculus). Rabbits exhibit a masticatory complex and feeding behaviors like primates, yet retain a primitive circumorbital region similar to their common ancestor. To address the plasticity and function of soft tissues of the lateral orbital wall, three cohorts of 10 rabbits each were raised from weaning (1 month old) to adulthood (6 months old) on diets of different mechanical properties (under-use, control, over-use). Once sacrificed, tissues were collected from the left lateral orbital wall. Dissections revealed that, rather than the anticipated postorbital ligament, rabbits instead exhibit fibrocartilage. Samples were analyzed histologically and immunohistochemically for general anatomy, fibril architecture, collagen expression/organization, and protein abundance using Western Blot analysis. Preliminary data suggests that collagen fibers are aligned differently, with an overexpression of collagen in the over-use dietary cohort versus both the control and under-use groups. In sum, these experimental findings suggest that the postorbital fibrocartilage is mechanically responsive, which contrasts with the non-masticatory nature of bony elements in the circumorbital region.Life Sciences Undergraduate Research Opportunity Progra

Should we modulate the neonatal microbiome and what should be the goal?

Peer reviewe

The role of docosahexaenoic acid in stress reprogramming and behavior

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT AUTHOR'S REQUEST.] The role of DHA (Docosahexaenoic acid [22:6(n-3)]) is known to play an important role in complex behaviors such as learning and memory, anxiety and depression. The work presented in this dissertation examines the role of DHA on sex-specific outcomes in two stress paradigms, social isolation in adulthood and chronic variable stress during pregnancy. In an animal model of early prenatal stress, reprogramming occured disproportionally in males, without an effect on females, and DHA enrichment provides a buffer against male-specific reprogramming in response to prenatal stress. Similarly, social isolation during adulthood results in sex-specific anxiety- and depressive-like phenotypes, which are reversed by DHA enrichment. males exhibited elevated anxiety-like behavior and anhedonia with parallel changes in gene expression patterns in the nucleus accumbens and ventral tegmental area, while DHA-enrichment reverses the male-specific anxiety-like behavior and anhedonia following social isolation and induces contrasting gene expression patterns in the nucleus accumbens and ventral tegmental area. Interestingly, DHAenrichment exhibited no disruptive or beneficial effect on females in either mouse model of stress, highlighting the possibility that the stress - diet axis exhibit separate mechanisms in males and females. These studies provide evidence that DHA enrichment during development, at least in part, regulates response to stress in a sex-specific manner by inducing sex-specific gene expression patterns that may lead the downstream expression of sex-specific behaviors

Effects of developmental bisphenol A exposure on reproductive-related behaviors in California mice (Peromyscus californicus): a monogamous animal model.

Bisphenol A (BPA), a pervasive, endocrine disrupting compound (EDC), acts as a mixed agonist-antagonist with respect to estrogens and other steroid hormones. We hypothesized that sexually selected traits would be particularly sensitive to EDC. Consistent with this concept, developmental exposure of males from the polygynous deer mouse, Peromyscus maniculatus, to BPA resulted in compromised spatial navigational ability and exploratory behaviors, while there was little effect on females. Here, we have examined a related, monogamous species, the California mouse (Peromyscus californicus), where we predicted that males would be less sensitive to BPA in terms of navigational and exploratory behaviors, while displaying other traits related to interactions with females and territorial marking that might be vulnerable to disruption. As in the deer mouse experiments, females were fed either a phytoestrogen-free CTL diet through pregnancy and lactation or the same diet supplemented with BPA (50 mg/kg feed weight) or ethinyl estradiol (EE) (0.1 part per billion) to provide a "pure" estrogen control. After weaning, pups were maintained on CTL diet until they had reached sexual maturity, at which time behaviors were evaluated. In addition, territorial marking was assessed in BPA-exposed males housed alone and when a control male was visible in the testing arena. In contrast to deer mice, BPA and EE exposure had no effect on spatial navigational skills in either male or female California mice. While CTL females exhibited greater exploratory behavior than CTL males, BPA exposure abolished this sex difference. BPA-exposed males, however, engaged in less territorial marking when CTL males were present. These studies demonstrate that developmental BPA exposure can disrupt adult behaviors in a sex- and species-dependent manner and are consistent with the hypothesis that sexually selected traits are particularly vulnerable to endocrine disruption and should be a consideration in risk assessment studies

Impact of Non-Valvular Non-Coronary Concomitant Procedures on Outcomes of Surgical Aortic Valve Replacement in Intermediate Risk Patients

Introduction: advanced age and concomitant procedures could increase the risk of perioperative complications during surgical aortic valve replacement (SAVR). We aimed to evaluate results of elderly patients undergoing SAVR and evaluate the impact of concomitant non-valvular, non-coronary procedures on the outcomes. Methods: A retrospective single-centre study, evaluating 464 elderly patients (mean age = 75.6 ± 4 years) undergoing either isolated-SAVR (I-SAVR = 211) or combined-SAVR (C-SAVR = 253) between 01/2007 and 12/2017. Combined-SAVR involved non-valvular, non-coronary procedures. Study endpoints are postoperative results concerning the VARC-II criteria, valve dysfunction, long-term freedom from redo-AVR and survival. Results: males were 52.8%. Patients had an intermediate risk profile (mean EuroSCORE-II (%) 5.2 ± 5). Postoperative results reported no significant differences in incidence of re-exploration for bleeding (6.6% vs. 6.7%, p = 1.0), stroke (0.9% vs. 0.4%, p = 0.59), dialysis (6.2% vs. 9.5%, p = 0.23) and pacemaker implantation (3.3% vs. 2.8%, p = 0.79) between I-SAVR and C-SAVR groups. Thirty-day (2.4% vs. 7.1% p = 0.03), one-year (5.7% vs. 13.8%, p = 0.003) and overall mortality (24.6% vs. 37.5%, p = 0.002) were lower in the isolated-SAVR group. Re-AVR was indicated in 1.7% of patients due to endocarditis. Conclusions: SAVR in elderly patients offers good outcomes with increased life quality and rare re-operation for structural valvular deterioration. Mortality rates were significantly higher when SAVR was combined with another “non-valvular, non-coronary” procedure

Measurements of exploratory and anxiety-like behaviors in EPM.

<p>a) Time spent in the open arms of the EPM. No difference was evident in time spent in the open arms between BPA- and EE-exposed males compared to CTL California mice males. In contrast, CTL female California mice spent more time in the open arms than BPA-exposed females and CTL males. ^a,bDifferences between maternal diets within sex (P<0.05), and ^*differences between sexes within maternal diet (P = 0.05). b) Proportion of time spent in open arms, c) Time spent immobile, d) Total number of entries in all arms, e) Distance travelled, and f) Velocity. None of these other measurements were affected by sex or maternal diet.</p

Barnes maze search strategy.

<p>The graph depicts the usage of random (yellow), serial (green), and direct (black) search strategies by CTL, EE-, and BPA-exposed males and females. During the seven d trial period, there were no consistent differences in search strategy based on maternal diet or sex.</p

Measurement of territorial marking in BPA-exposed California mice males compared to CTL males.

<p>There was no difference on d 0 between BPA-exposed and CTL males, who did not have any visual or other sensory contact. When BPA-exposed and CTL males were placed in the same cage with a barrier between them, BPA-exposed males exhibited a trend to engage in less territorial marking on the first d of exposure (P<0.07) and even more so seven ds later than CTL males (*, P<0.003).</p

Body weight measurements of California mice males and females exposed to BPA, EE, and CTL diet.

<p>Measurements of body weight from 30 to 90 ds of age indicated that in males developmental exposure to BPA or EE did not affect body weight gain. In contrast, females exposed to EE weighed less than CTL females, EE males, and BPA females (P<0.05).</p