High circulating concentrations of estradiol are anabolic for bone mass and strength in an adult male to female transgender mouse model.

The effects of gender affirming hormone therapy (GAHT) on bone microarchitecture and fracture risk in adult transgender women is unclear. To investigate the concept that skeletal integrity and strength in trans women may be improved by treatment with a higher dose of GAHT than commonly prescribed, we treated adult male mice with a sustained, high dose of estradiol. Adult male mice at 16 weeks of age were administered ~1.3 mg estradiol by silastic implant, implanted intraperitoneally, for 12 weeks. Controls included vehicle treated intact females and males. High-dose estradiol treatment in males stimulated the endocortical deposition of bone at the femoral mid-diaphysis, increasing cortical thickness and bone area. This led to higher stiffness, maximum force, and the work required to fracture the bone compared to male controls, while post-yield displacement was unaffected. Assessment of the material properties of the bone showed an increase in both elastic modulus and ultimate stress in the estradiol treated males. Treatment of male mice with high dose estradiol was also anabolic for trabecular bone, markedly increasing trabecular bone volume, number and thickness in the distal metaphysis which was accompanied by an increase in the histomorphometric markers of bone remodelling, mineralizing surface/bone surface, bone formation rate and osteoclast number. In conclusion, a high dose of estradiol is anabolic for cortical and trabecular bone in a male to female transgender mouse model, increasing both stiffness and strength. These findings suggest that increasing the current dose of GAHT administered to trans women, while considering other potential adverse effects, may be beneficial to preserving their bone microstructure and strength.

Estradiol increases cortical and trabecular bone accrual and bone strength in an adolescent male-to-female mouse model of gender-affirming hormone therapy.

The effects of gender-affirming hormone therapy on the skeletal integrity and fracture risk in transitioning adolescent trans girls are unknown. To address this knowledge gap, we developed a mouse model to simulate male-to-female transition in human adolescents in whom puberty is first arrested by using gonadotrophin-releasing hormone analogs with subsequent estradiol treatment. Puberty was suppressed by orchidectomy in male mice at 5 weeks of age. At 3 weeks post-surgery, male-to-female mice were treated with a high dose of estradiol (~0.85 mg) by intraperitoneal silastic implantation for 12 weeks. Controls included intact and orchidectomized males at 3 weeks post-surgery, vehicle-treated intact males, intact females and orchidectomized males at 12 weeks post-treatment. Compared to male controls, orchidectomized males exhibited decreased peak bone mass accrual and a decreased maximal force the bone could withstand prior to fracture. Estradiol treatment in orchidectomized male-to-female mice compared to mice in all control groups was associated with an increased cortical thickness in the mid-diaphysis, while the periosteal circumference increased to a level that was intermediate between intact male and female controls, resulting in increased maximal force and stiffness. In trabecular bone, estradiol treatment increased newly formed trabeculae arising from the growth plate as well as mineralizing surface/bone surface and bone formation rate, consistent with the anabolic action of estradiol on osteoblast proliferation. These data support the concept that skeletal integrity can be preserved and that long-term fractures may be prevented in trans girls treated with GnRHa and a sufficiently high dose of GAHT. Further study is needed to identify an optimal dose of estradiol that protects the bone without adverse side effects.

The Utility of Preclinical Models in Understanding the Bone Health of Transgender Individuals Undergoing Gender-Affirming Hormone Therapy.

PURPOSE OF REVIEW: To summarise the evidence regarding the effects of gender-affirming hormone therapy (GAHT) on bone health in transgender people, to identify key knowledge gaps and how these gaps can be addressed using preclinical rodent models. RECENT FINDINGS: Sex hormones play a critical role in bone physiology, yet there is a paucity of research regarding the effects of GAHT on bone microstructure and fracture risk in transgender individuals. The controlled clinical studies required to yield fracture data are unethical to conduct making clinically translatable preclinical research of the utmost importance. Novel genetic and surgical preclinical models have yielded significant mechanistic insight into the roles of sex steroids on skeletal integrity. Preclinical models of GAHT have the potential inform clinical approaches to preserve skeletal integrity and prevent fractures in transgender people undergoing GAHT. This review highlights the key considerations required to ensure the information gained from preclinical models of GAHT are informative.

Distinct impacts of polar and nematic self-propulsion on active unjamming.

Though jamming transitions are long studied in condensed matter physics and granular systems, much less is known about active jamming (or unjamming), which commonly takes place in living materials. In this paper, we explore, by molecular dynamic simulations, the jamming-unjamming transition in a dense system of active semiflexible filaments. In particular, we characterize the distinct impact of polar vs nematic driving for different filament rigidities and at varying densities. Our results show that high densities of dynamic active filaments can be achieved by only changing the nature of the active force, nematic or polar. Interestingly, while polar driving is more effective at unjamming the system at high densities below confluency, we find that at even higher densities, nematic driving enhances unjamming compared to its polar counterpart. The effect of varying the rigidity of filaments is also significantly different in the two cases: While for nematic driving, lowering the bending rigidity unjams the system, we find an intriguing reentrant jamming-unjamming-jamming transition for polar driving as the filament rigidity is lowered. While the first transition (unjamming) is driven by softening due to reduced rigidity, the second transition (jamming) is a cooperative effect of ordering and coincides with the emergence of nematic order in the system. Together, through a generic model of self-propelled flexible filaments, our results demonstrate how tuning the nature of self-propulsion and flexibility can be employed by active materials to achieve high densities without getting jammed.

The AR in bone marrow progenitor cells protects against short-term high-caloric diet-induced weight gain in male mice.

We previously identified a novel pathway of testosterone action via the androgen receptor (AR) in bone marrow mesenchymal precursor cells (BM-PCs) to negatively regulate fat mass and improve metabolic function in male mice. This was achieved using our PC-AR Gene Replacement mouse model in which the AR is only expressed in BM-PCs and deleted in all other tissues. We hypothesise that the markedly reduced fat mass and increased insulin sensitivity of PC-AR Gene Replacements will confer protection from diet-induced overweight and obesity. To test this, 6-week-old male PC-AR Gene Replacements and controls (WT, global-AR knockouts (KOs)) were fed a chow or high-caloric diet (HCD) for 8 or 18 weeks. Following 8 weeks (short-term) of HCD, WT and Global-ARKOs had markedly increased subcutaneous white adipose tissue (WAT) and retroperitoneal visceral adipose tissue (VAT) mass compared to chow-fed controls. In contrast, PC-AR Gene Replacements were resistant to WAT and VAT accumulation following short-term HCD feeding accompanied by fewer large adipocytes and upregulation of expression of the metabolic genes Acaca and Pnlpa2. Following long-term HCD feeding for 18 weeks, the PC-AR Gene Replacements were no longer resistant to increased WAT and VAT adiposity, however, maintained their improved whole-body insulin sensitivity with an increased rate of glucose disappearance and increased glucose uptake into subcutaneous WAT. In conclusion, the action of testosterone via the AR in BM-PCs to negatively regulate fat mass and improve metabolism confers resistance from short-term diet-induced weight gain and partial protection from long-term diet-induced obesity in male mice.

The role of the androgen receptor in the pathogenesis of obesity and its utility as a target for obesity treatments.

Obesity is associated with hypothalamic-pituitary-testicular axis dysregulation in males. Here, we summarize recent evidence derived from clinical trials and studies in preclinical animal models regarding the role of androgen receptor (AR) signaling in the pathophysiology of males with obesity. We also discuss therapeutic strategies targeting the AR for the treatment of obesity and their limitations and provide insight into the future research necessary to advance this field.

Distinct roles of androgen receptor, estrogen receptor alpha, and BCL6 in the establishment of sex-biased DNA methylation in mouse liver.

Sexual dimorphism in gene regulation, including DNA methylation, is the main driver of sexual dimorphism in phenotypes. However, the questions of how and when sex shapes DNA methylation remain unresolved. Recently, using mice with different combinations of genetic and phenotypic sex, we identified sex-associated differentially methylated regions (sDMRs) that depended on the sex phenotype. Focusing on a panel of validated sex-phenotype dependent male- and female-biased sDMRs, we tested the developmental dynamics of sex bias in liver methylation and the impacts of mutations in the androgen receptor, estrogen receptor alpha, or the transcriptional repressor Bcl6 gene. True hermaphrodites that carry both unilateral ovaries and contralateral testes were also tested. Our data show that sex bias in methylation either coincides with or follows sex bias in the expression of sDMR-proximal genes, suggesting that sex bias in gene expression may be required for demethylation at certain sDMRs. Global ablation of AR, ESR1, or a liver-specific loss of BCL6, all alter sDMR methylation, whereas presence of both an ovary and a testis delays the establishment of male-type methylation levels in hermaphrodites. Moreover, the Bcl6-LKO shows dissociation between expression and methylation, suggesting a distinct role of BCL6 in demethylation of intragenic sDMRs.

Genetic Knockout of the Serotonin Reuptake Transporter Results in the Reduction of Dendritic Spines in In vitro Rat Cortical Neuronal Culture.

Dysregulation of the serotonergic system has been reported to have a significant role in several neurological disorders including depression, autism and substance abuse disorders. Changes in the expression of the serotonin transporter (SERT) through polymorphisms in the regulatory regions of the SERT gene have been associated, but not yet been conclusively linked to, neuropsychiatric disorders. In turn, dendritic spine structure and function are critical for neuronal function and the disruption of dendritic spine formation at glutamatergic synapses is a hallmark of several neuropsychiatric disorders. To understand the effect of SERT depletion on dendritic spine formation, neuronal cultures were established from the cortex of postnatal day 0-1 SERT knockout (KO) rats. Cortical neurons were subsequently allowed to mature to 21 days in vitro, and dendritic spine density was assessed using immunocytochemical co-labelling of drebrin and microtubule associated protein 2. Genetic knockout of the SERT had a gene-dose effect on dendritic spine densities of cortical neurons. The results of this paper implicate SERT function with the formation of dendritic spines at glutamatergic synapses, thereby offering insight into the aetiology of several neuropathologies.

Molecular investigation of Coleopteran specific α-Amylase inhibitors from Amaranthaceae members.

α-Amylase inhibitors (α-AIs) target α-amylases and interfere with the carbohydrate digestion of insects. Among different classes of α-AIs, a knottin-type inhibitor from Amaranthus hypochondriacus (AhAI) was found to be specific against coleopteran storage pests. In this report, we have characterized three previously unidentified knottin-type α-AIs from various Amaranthaceae plants namely, Amaranthus hypochondriacus (AhAI2), Alternanthera sessilis (AsAI) and Chenopodium quinoa (CqAI). They contain a signal peptide, pro-peptide, and mature peptide. The mature peptides of the new α-AIs shared 68 to 78% identity with AhAI and have highly variable pro-peptide regions. Along with the cystine-knot fold, they showed conservation of reactive site residues. All recombinant α-AIs were successfully expressed in their active form and native state using an oxidative cytoplasmic environment. Inhibition studies against various amylases revealed that these inhibitors showed selective inhibition of coleopteran recombinant insect α-amylases viz., Tribolium castaneum, and Callosobruchus chinensis. Tribolium castaneum α-amylase inhibition potency was highest for AhAI2 (Ki ~ 15 µM) followed by AsAI (Ki ~ 43 µM) and CqAI (Ki ~ 61 µM). Interaction analysis of these inhibitors illustrated that the reactive site of inhibitors make several non-covalent interactions with the substrate-binding pocket of coleopteran α-amylases. The selectivity of these inhibitors against coleopteran α-amylases highlights their potential in storage grain pest control.

Tunneling nanotubes: A bridge for heterogeneity in glioblastoma and a new therapeutic target?

BACKGROUND: The concept of tumour heterogeneity is not novel but is fast becoming a paradigm by which to explain part of the highly recalcitrant nature of aggressive malignant tumours. Glioblastoma is a prime example of such difficult-to-treat, invasive, and incurable malignancies. With the advent of the post-genomic age and increased access to next-generation sequencing technologies, numerous publications have described the presence and extent of intratumoural and intertumoural heterogeneity present in glioblastoma. Moreover, there have been numerous reports more directly correlating the heterogeneity of glioblastoma to its refractory, reoccurring, and inevitably terminal nature. It is therefore prudent to consider the different forms of heterogeneity seen in glioblastoma and how to harness this understanding to better strategize novel therapeutic approaches. One of the most central questions of tumour heterogeneity is how these numerous different cell types (both tumour and non-tumour) in the tumour mass communicate. RECENT FINDINGS: This chapter provides a brief review on the variable heterogeneity of glioblastoma, with a focus on cellular heterogeneity and on modalities of communication that can induce further molecular diversity within the complex and ever-evolving tumour microenvironment. We provide particular emphasis on the emerging role of actin-based cellular conduits called tunnelling nanotubes (TNTs) and tumour microtubes (TMs) and outline the perceived current problems in the field that need to be resolved before pharmacological targeting of TNTs can become a reality. CONCLUSIONS: We conclude that TNTs and TMs provide a new and exciting avenue for the therapeutic targeting of glioblastoma and that numerous inroads have already made into TNT and TM biology. However, to target TMs and TNTs, several advances must be made before this aim can become a reality.

Occupation Hazards - Pattern, Awareness and Preventive Measures among Welders from an Unorganized Sector in India.

INTRODUCTION: Welding is an occupation associated with tremendous physical and chemical hazards. In spite of the risk involved, usage of Personal Protective Gears (PPGs) among welders in developing countries has been reported to be poor, due to their limited awareness of occupational hazards. AIM: To assess morbidity pattern, awareness of occupational hazards and usage practices of protective gears among welders. MATERIALS AND METHODS: Cross-sectional study was conducted at welding sites from unorganized sector situated in and around Mangalore. A total of 155 welders chosen randomly from as many sites were interviewed at their workplace using a pilot tested structured interview schedule with both closed and open ended questions. Clinical examination of the participant and inspection of the work site was also done by the investigators. Statistical analysis used for analysis was Chi-Square test, unpaired t-test and ANOVA test. RESULTS: Working >8 hours a day was reported by 30 (19.4%) welders. Overcrowding was present at 10.3%, ventilation status was inadequate at 6.9% and exhaust ventilation was not present at 25.9% sites. Awareness about occupational health hazards associated with welding was present among 97(62.6%) welders. Periodicity of medical examination was associated with awareness of occupational hazards among welders (p=0.032). First aid kit was present at 60 (38.7%) sites. The most common morbidity over the past year was wounds 119 (76.8%). Non-usage of most essential protective gears such as face shields, masks or eye goggles was seen among 18 (11.6%) welders. Mean number of morbidities over the past one month was found to be more, in those welders doing continuous work of ≥6 hours (p=0.05), at sites with overcrowding (p=0.002) and at sites where >10 welders work together (p=0.031). CONCLUSION: The period prevalence of morbidity was high among the welders surveyed. Ignorance of health hazards associated with occupation and non-usage of protective gears was reported by number of them. Therefore, health education and safety policies need to be strengthened at welding sites.

Thrombomodulin Binding Selects the Catalytically Active Form of Thrombin.

Human α-thrombin is a serine protease with dual functions. Thrombin acts as a procoagulant, cleaving fibrinogen to make the fibrin clot, but when bound to thrombomodulin (TM), it acts as an anticoagulant, cleaving protein C. A minimal TM fragment consisting of the fourth, fifth, and most of the sixth EGF-like domain (TM456m) that has been prepared has much improved solubility, thrombin binding capacity, and anticoagulant activity versus those of previous TM456 constructs. In this work, we compare backbone amide exchange of human α-thrombin in three states: apo, D-Phe-Pro-Arg-chloromethylketone (PPACK)-bound, and TM456m-bound. Beyond causing a decreased level of amide exchange at their binding sites, TM and PPACK both cause a decreased level of amide exchange in other regions including the γ-loop and the adjacent N-terminus of the heavy chain. The decreased level of amide exchange in the N-terminus of the heavy chain is consistent with the historic model of activation of serine proteases, which involves insertion of this region into the ß-barrel promoting the correct conformation of the catalytic residues. Contrary to crystal structures of thrombin, hydrogen-deuterium exchange mass spectrometry results suggest that the conformation of apo-thrombin does not yet have the N-terminus of the heavy chain properly inserted for optimal catalytic activity, and that binding of TM allosterically promotes the catalytically active conformation.