Pubertal growth and epiphyseal fusion

Hormonal Control of Bone Architecture Throughout the Lifespan: Implications for Fracture Prediction and Prevention

BACKGROUND

Skeletal modeling in childhood and adolescence and continuous remodeling throughout the lifespan are designed to adapt to a changing environment and resist external forces and fractures. The flux of sex steroids in men and women, beginning from fetal development and evolving through infancy, childhood, puberty, young adulthood, peri/menopause transition, and postmenopause, is critical for bone size, peak bone mass, and fracture resistance.

OBJECTIVE

This review will highlight how changes in sex steroids throughout the lifespan affect bone cells and the consequence of these changes on bone architecture and strength.

METHODS

Literature review and discussion.

RESULTS

The contributions of estrogen and testosterone on skeletal development have been difficult to study due to the reciprocal and intertwining contributions of one on the other. Although orchiectomy in men renders circulating testosterone absent, circulating estrogen also declines due to testosterone being the substrate for estradiol. The discovery of men with absent estradiol or resistance to estrogen and the study of mouse models led to the understanding that estrogen has a larger direct role in skeletal development and maintenance in men and women. The mechanistic reason for larger bone size in men is incompletely understood but related to indirect effects of testosterone on the skeleton, such as higher muscle mass leading to larger mechanical loading. Declines in sex steroids during menopause in women and androgen deprivation therapies in men have profound and negative effects on the skeleton. Therapies to prevent such bone loss are available, but how such therapies can be tailored based on bone size and architecture remains an area of investigation.

CONCLUSION

In this review, the elegant interplay and contribution of sex steroids on bone architecture in men and women throughout the lifespan is described.

Evidence of weight loss in junior female judo athletes affects their development

Purpose

The facile manipulation of body weight in junior athletes has the potential to pose significant risks to their lifelong health. In judo, which is a weight class sport, pre-competition weight loss is widespread even among juniors, but information on the current situation is scarce, especially for female athletes, for whom it is important to provide adequate nutrition and enhance bone mass during the growth period, and the details of the current situation are not clear. Therefore, the purpose of this study was to determine the actual weight loss during the growth period in junior female judo athletes and its subsequent impact on their health.

Methods

The survey was a cross-sectional survey of junior female judo athletes in Japan using a questionnaire. Participants were asked to respond via an online questionnaire about their weight, height, weight loss experience, menstruation, competition results, and other lifestyle.

Results

51.8% of subjects experienced weight loss for competition during their junior high school years (ages 12-15). Those who experienced weight loss during secondary sexual characteristics were found to be significantly shorter in current height than those who did not (p < 0.05). Weight loss during secondary sexual characteristics did not affect current menstrual cycle. There was no significant difference in competition results due to the experience of weight loss during junior high school (χ 2 = 4.485, df = 3, n.s.).

Conclusions

These findings suggest that weight loss during the growth spurt phase may adversely impact normal development. It also suggested that weight loss during the junior high school years may not be a strategy to bring about better competition results. These observations indicate the need for education on appropriate class selection and weight control for junior athletes in weight class competitions.

Aromatase inhibitors: a useful additional therapeutic option for slowing down advanced bone age in boys with growth hormone deficiency

INTRODUCTION

Aromatase inhibitors (AIs) have been used to slow down estrogen-dependent skeletal maturation in pubertal boys with short stature. In the literature, few data evaluate the effectiveness and safety of AIs in boys with growth hormone deficiency (GHD). This study aimed to evaluate the auxologic effects and short-term laboratory profiles of combined AI and rhGH therapy for 1 year in adolescent males with GHD.

SUBJECTS AND METHODS

Male subjects between the ages of 10 and 16 with GHD from two different centers were included in the study. Patients were divided into two groups: (i) those who only used recombinant human growth hormone (rhGH) therapy (Group I; G-I) and (ii) those who also used AI therapy (anastrozole or letrozole) along with rhGH (Group II; G-II).

RESULTS

Forty-one patients (G-I, 46%; G-II, 54%) were included in the study. All the subjects had isolated GHD. At the beginning of the treatment, the chronological ages (CAs) of the patients in the G-I and G-II groups were 11.8 (10.9-13.7) and 12.8 (12.0-14.3) years, respectively. The ratios of bone age (BA)/CA for the two groups were 0.8 (0.8-0.9) and 1.0 (0.9-1.1), respectively (p < 0.001). After the treatment, the height standard deviation (SD) scores and predicted adult height (PAH) significantly increased from baseline in all subjects in the G-I and G-II groups (p < 0.001; p < 0.001, respectively). There was no significant change in the ratio of BA/CA post-therapy in the G-I group (p = 0.1), while there was a significant decrease in the G-II group (p < 0.001). The growth velocities of the patients in the G-I and G-II groups were 9.1 (7.4-10.1) cm/year [1.5 (0.8-5.0) SD score] and 8.7 (7.5-9.9) cm/year [1.1 (0.3-3.1) SD score], respectively (p = 0.6). While post-therapy serum testosterone concentrations were seen to increase in the G-II group, none of the patients exhibited hematocrit above 50 percent, and the fasting glucose concentrations were normal.

CONCLUSIONS

When used in addition to rhGH therapy in boys with GHD and advanced BA, AIs were observed to slow down the tempo of BA maturation after 1 year, compared to those who received rhGH treatment alone. AI therapy was found to be safe during the 1-year observation period and thus could be considered for preserving growth potential in these patients.

Secular trends and regional pattern in body height of Austrian conscripts born between 1961 and 2002

The human growth process is influenced not only by genetic factors but also by environmental factors. Therefore, regional differences in mean body heights may exist within a population or a state. In the present study, we described and evaluated the regional trends in mean body heights in the nine Austrian provinces over a period spanning more than four decades. Body height data of 1734569 male conscripts born in Austria with Austrian citizenship between 1961 and 2002 were anonymized and analyzed. From 1961 to 2002 birth cohorts, an overall increase in the mean body height of Austrian recruits was observed, although regional differences were evident. Regions with shorter body heights in the 1961-1963 birth cohorts showed a particularly pronounced increase in mean body heights. Meanwhile, the course of body height growth in the capital city, Vienna, was striking, where the highest body heights were documented for the 1961-1963 birth cohorts. In Vienna, mean body heights continued to decline until the 1984 birth cohort and increased again from the 1988 birth cohorts. In addition to economic factors, increased stress factors in an urban environment and a form of urban penalty are discussed as causes.

Anterior knee laxity is greater in athletic females who attain menarche at a younger age

PURPOSE

Females with above-average anterior knee laxity values are at increased risk of anterior cruciate ligament (ACL) injury. The purpose of this study was to examine the effects of menarche age (MA) and menarche offset on anterior knee laxity in young, physically active women.

METHODS

Anterior knee laxity (KT-2000) and menstrual characteristics (per self-report) were recorded in 686 Slovenian sportswomen from team handball, volleyball and basketball club sports (average years sport participation: 7.3 ± 3.6 years). Females were stratified into four groups based on their self-reported age at menarche: 9-11, 12, 13 and 14+ years. Anterior knee laxity was compared across MA groups using a univariate analysis of variance (ANOVA) with Bonferroni correction, with and without controlling for factors that could potentially differ between groups and influence anterior knee laxity. Females were then stratified into four groups based on the number of years they were away from their age at onset of menarche. Groups were compared using a univariate ANOVA with Bonferroni correction, with and without controlling for factors that differed between groups and could influence anterior knee laxity.

RESULTS

Anterior knee laxity was greater in females who attained menarche at 12 years of age (6.4 ± 1.5 mm) or younger (6.6 ± 1.6 mm) compared to 14 years of age or older (5.8 ± 1.2 mm) (p < 0.001; partial η2 = 0.032). Anterior knee laxity was 0.7-1.4 mm greater in females who were 5 or more years away from menarche compared to those who were within 2 years of menarche (5.8 ± 1.3 mm; p < 0.001).

CONCLUSION

Anterior knee laxity is greater in females who attained menarche at a younger age and in females who are 5 or more years postmenarche. Age of menarche represents a critical pubertal event that is easy for women to recall and may provide important insights into factors that moderate anterior knee laxity, a risk factor for ACL injury in women.

LEVEL OF EVIDENCE

Level IV.

Depletion of SMN protein in mesenchymal progenitors impairs the development of bone and neuromuscular junction in spinal muscular atrophy

Spinal muscular atrophy (SMA) is a neuromuscular disorder characterized by the deficiency of the survival motor neuron (SMN) protein, which leads to motor neuron dysfunction and muscle atrophy. In addition to the requirement for SMN in motor neurons, recent studies suggest that SMN deficiency in peripheral tissues plays a key role in the pathogenesis of SMA. Using limb mesenchymal progenitor cell (MPC)-specific SMN-depleted mouse models, we reveal that SMN reduction in limb MPCs causes defects in the development of bone and neuromuscular junction (NMJ). Specifically, these mice exhibited impaired growth plate homeostasis and reduced insulin-like growth factor (IGF) signaling from chondrocytes, rather than from the liver. Furthermore, the reduction of SMN in fibro-adipogenic progenitors (FAPs) resulted in abnormal NMJ maturation, altered release of neurotransmitters, and NMJ morphological defects. Transplantation of healthy FAPs rescued the morphological deterioration. Our findings highlight the significance of mesenchymal SMN in neuromusculoskeletal pathogenesis of SMA and provide insights into potential therapeutic strategies targeting mesenchymal cells for the treatment of SMA.

Standing Tall: Do Height-Based Accountability Incentives Predict Artificial Increases in Measured Height Among Sailors in the U.S. Military?

INTRODUCTION

The objective of this study was to investigate the changes in men's and women's measured height in response to weight gain above standards for the U.S. Navy and to quantify associated distortions in body mass index (BMI). We expected that some servicemembers would manipulate their measured height to comply with service standards.

MATERIALS AND METHODS

The study was a retrospective observational study. The data were housed in the Person-Event Data Environment, an individual-level administrative registry from the United States Department of Defense. All participants were active-duty U.S. Navy sailors aged 21-50 during the years 2010-2019. The main outcomes were height and weight as recorded during twice-yearly physical fitness assessments and BMI calculated as: height in pounds × 703/(height in inches)2. We assessed whether weight gain above standards was associated with an increase in height at the subsequent height-weight assessment.

RESULTS

Among the 489,020 sailors, individuals were nearly 1.5 times as likely to measure taller when they gained weight that put them above military height-weight standards as compared to those who continued to remain within standards. Men were more often out of standards and therefore their measured height increased during subsequent assessments more often than women. Increases in height depressed measures of BMI slightly.

CONCLUSIONS

Among U.S. sailors, taller height was correlated with surpassing height-based weight limits, where taller individuals were allowed to weigh more and still meet professional weight standards. Results underscore that current height-weight accountability standards may distort behavior, leading servicemembers to manipulate measurements rather than improve job-relevant fitness. Instead, greater reliance on fitness-based measures of health, such as fitness tests, may hold promise for upholding servicemember readiness. Our results highlight that when stakes are attached to a measure, individuals may work to raise their performance using strategies that are misaligned with the policy intent.

Relationship between testosterone-estradiol ratio and some anthropometric and metabolic parameters among Nigerian men

Background

Alterations in sex hormone levels are implicated in the regulation of metabolic processes in men. In recent years, the prevalence of metabolic disorders, such as obesity, insulin resistance, and type 2 diabetes, has risen in Nigeria. In men, these disorders may be associated with the ratio of serum testosterone to estradiol levels. Therefore, we investigated the relationship between the testosterone-estradiol (T/E2) ratio, anthropometry, and metabolic parameters in Nigerian men.

Method

Eighty-five adult men were recruited for this study. Participants' data such as age, weight, height, BMI, and waist circumference were collected. Plasma total testosterone and estradiol levels, as well as metabolic parameters such as fasting blood sugar, creatinine, urea, HDL cholesterol, total cholesterol, and triglycerides levels, were determined. The data were analyzed using SPSS version 25 software.

Results

Anthropometric parameters such as weight, height, BMI, and waist circumference showed a negative correlation with plasma T/E2 (r = -0.265, -0.288, -0.106, -0.204; p = 0.007, 0.004, 0.167, 0.061 respectively). However, the T/E2 ratio showed a positive correlation with the metabolic parameters such as fasting blood sugar, HDL cholesterol levels, plasma creatinine, and urea (r = 0.219, 0.096, 0.992, 0.152; p = 0.022, 0.192, <0.001, 0.082 respectively), while there were negative correlations with total cholesterol and triglycerides levels (r = -0.200, -0.083; p = 0.034, 0.226 respectively).

Conclusion

These findings show that there are significant correlations between the T/E2 ratio and weight, height, fasting blood sugar, creatinine, and urea, while there are no significant correlations between T/E2 ratio and BMI, waist circumference, HDL-cholesterol, and triglycerides.

Morphologic aspects of the cervical (C3 to C7) annular epiphysis: a skeletal study

BACKGROUND CONTEXT

The annular epiphysis (AE) is a peripheral ring of cortical bone that forms a secondary ossification center in the superior and inferior surfaces of vertebral bodies (VBs). The AE is the last ossification site in the skeleton, typically forming at about the 25th year of life. The AE functions jointly with vertebral endplates to anchor the intervertebral discs to the VBs.

PURPOSE

To establish accurate data on the sizes of the AE of the cervical spine (C3-C7); to compare the ratios between areas and the ratios of the AE to VBs; to compare the ratios between the superior and inferior VB surface areas; and to compare AE lengths between the posterior and anterior midsagittal areas.

STUDY DESIGN

Measurement of 424 cervical spines (C3-C7) obtained from the skeletal collection of the Natural History Museum, Cleveland, Ohio (USA).

METHODS

The sample was characterized by sex, age, and ethnic origin. The following measurements were recorded for each vertebra: (1) the surface area of the VBs and the AE, (2) the midsagittal anterior and posterior length of the AE, (3) the ratios between the AE and VB surface areas, and (4) the ratios between the superior and inferior disc surface areas.

RESULTS

The study revealed that the AE and VBs in men were larger than in women. With age, the AE and VBs became larger; the ratio between the AE and VB surface was ∼0.5 throughout the middle to lower cervical spine. The ratio of superior to inferior VBs was ∼0.8. We found no differences between African Americans versus European Americans or between the anterior versus the posterior midsagittal length of the AE of the superior and inferior VBs.

CONCLUSION

The ratios between the superior and inferior VBs is ≥0.8, and the ratio is the same for the entire middle to lower spine. Thus, the ratio between the superior and inferior VBs to the AE is ≥ 0.5. Men had larger AEs and VBs than women did, with both VBs and AEs becoming larger with age. Knowing these relationships are important so that orthopedic surgeons can best correct these issues in young patients (<25 years old) during spine surgery. The data reported here provide, for the first time, all the relevant sizes of the AE and VB. In future studies, AEs and VBs of living patients can be measured with computed tomography.

CLINICAL SIGNIFICANCE

The ER location and function are clinically significant showing any changes during life that might lead to clinical issues related to intervertebral discs such as intervertebral disc asymmetry, disc herniation, nerve pressure, cervical osteophytes and neck pain.

Using change in predicted adult height during GnRH agonist treatment for individualized treatment decisions in girls with central precocious puberty

OBJECTIVES

It is important to understand what variables influence change in predicted adult height (PAH) throughout GnRHa treatment for central precocious puberty (CPP) to individualize treatment decisions and optimize care.

METHODS

Changes in PAH, chronological age (CA), bone age (BA), BA/CA, and height velocity (HV) were evaluated in girls with CPP throughout treatment with leuprolide acetate (n=77). A second analysis focused on changes in the 3 years preceding the first observed BA of ≥12 years. Relationships were characterized using plot inspection and linear mixed-effects analyses. Association between treatment duration and last assessed PAH was examined using multiple linear regression models.

RESULTS

BA/CA and HV showed a nonlinear change during treatment, with the largest changes and improvement in PAH observed in the first 6-18 months. Rate of BA advancement tended to decrease more slowly in girls initiating treatment at a younger BA. On-treatment change in PAH was predicted by concurrent BA/CA change, HV, and BA, as well as CA at treatment initiation. Last assessed PAH was positively associated with longer treatment durations (primary/exploratory models cut-offs of ≥33/≥55 months).

CONCLUSIONS

These findings support individualized monitoring during GnRHa treatment. Initial response should be interpreted with caution until 6-18 months after treatment initiation and failure should not be assumed based on continued bone maturation in girls starting therapy at a younger age. Treatment cessation should not be automatically based on a diminishing change in PAH or HV, as ongoing treatment may result in continued increase or maintenance of PAH.

Electrosprayed Particles Loaded with Kartogenin as a Potential Osteochondral Repair Implant

The restoration of cartilage damage is a slow and not always successful process. Kartogenin (KGN) has significant potential in this space-it is able to induce the chondrogenic differentiation of stem cells and protect articular chondrocytes. In this work, a series of poly(lactic-co-glycolic acid) (PLGA)-based particles loaded with KGN were successfully electrosprayed. In this family of materials, PLGA was blended with a hydrophilic polymer (either polyethyleneglycol (PEG) or polyvinylpyrrolidone (PVP)) to control the release rate. Spherical particles with sizes in the range of 2.4-4.1 µm were fabricated. They were found to comprise amorphous solid dispersions, with high entrapment efficiencies of >93%. The various blends of polymers had a range of release profiles. The PLGA-KGN particles displayed the slowest release rate, and blending with PVP or PEG led to faster release profiles, with most systems giving a high burst release in the first 24 h. The range of release profiles observed offers the potential to provide a precisely tailored profile via preparing physical mixtures of the materials. The formulations are highly cytocompatible with primary human osteoblasts.

A 3D printed mimetic composite for the treatment of growth plate injuries in a rabbit model

Growth plate injuries affecting the pediatric population may cause unwanted bony repair tissue that leads to abnormal bone elongation. Clinical treatment involves bony bar resection and implantation of an interpositional material, but success is limited and the bony bar often reforms. No treatment attempts to regenerate the growth plate cartilage. Herein we develop a 3D printed growth plate mimetic composite as a potential regenerative medicine approach with the goal of preventing limb length discrepancies and inducing cartilage regeneration. A poly(ethylene glycol)-based resin was used with digital light processing to 3D print a mechanical support structure infilled with a soft cartilage-mimetic hydrogel containing chondrogenic cues. Our biomimetic composite has similar mechanical properties to native rabbit growth plate and induced chondrogenic differentiation of rabbit mesenchymal stromal cells in vitro. We evaluated its efficacy as a regenerative interpositional material applied after bony bar resection in a rabbit model of growth plate injury. Radiographic imaging was used to monitor limb length and tibial plateau angle, microcomputed tomography assessed bone morphology, and histology characterized the repair tissue that formed. Our 3D printed growth plate mimetic composite resulted in improved tibial lengthening compared to an untreated control, cartilage-mimetic hydrogel only condition, and a fat graft. However, in vivo the 3D printed growth plate mimetic composite did not show cartilage regeneration within the construct histologically. Nevertheless, this study demonstrates the feasibility of a 3D printed biomimetic composite to improve limb lengthening, a key functional outcome, supporting its further investigation as a treatment for growth plate injuries.

Strategies to Convert Cells into Hyaline Cartilage: Magic Spells for Adult Stem Cells

Damaged hyaline cartilage gradually decreases joint function and growing pain significantly reduces the quality of a patient’s life. The clinically approved procedure of autologous chondrocyte implantation (ACI) for treating knee cartilage lesions has several limits, including the absence of healthy articular cartilage tissues for cell isolation and difficulties related to the chondrocyte expansion in vitro. Today, various ACI modifications are being developed using autologous chondrocytes from alternative sources, such as the auricles, nose and ribs. Adult stem cells from different tissues are also of great interest due to their less traumatic material extraction and their innate abilities of active proliferation and chondrogenic differentiation. According to the different adult stem cell types and their origin, various strategies have been proposed for stem cell expansion and initiation of their chondrogenic differentiation. The current review presents the diversity in developing applied techniques based on autologous adult stem cell differentiation to hyaline cartilage tissue and targeted to articular cartilage damage therapy.

How do bones grow? A mathematical description of the mechanobiological behavior of the epiphyseal plate

Growth modulation is an emerging method for the treatment of skeletal deformities originating in the long bones or the vertebral bodies. It requires the controlled application of mechanical loads to the affected bone, causing an alteration of the growth and ossification process occurring in a cartilaginous region called epiphyseal growth plate or physis. In order to avoid the possibility of under- or over-correction, quantification of the applied forces is necessary. Pursuing this goal, here we propose a phenomenological model of mechanobiological effects on the epiphyseal growth plate, based on the observed similarity between the mechanobiologically induced growth and viscoelastic material behavior. The model incorporates mechanical loading effects on growth direction, growth rate and ossification speed; it also allows to evaluate the occurrence of transient effects. Model consistency was tested against a rather large set of experiments existing in the literature. A generic simplified geometrical model of bones was established for this. Analytical solutions for growth and ossification evolution were obtained for different loading conditions, allowing to test the ability of the model to describe bone growth under various kinds of mechanical loading conditions. Model-predicted changes regarding epiphyseal growth plate thickness as well as longitudinal growth speed are consistent with experiments in which static tension or compression were applied to long bones. Results suggest that when the mechanical load is sinusoidally variable, conflicting data existing in the literature could be explained by a previously unconsidered effect of the the applied load initial phase. The model can accurately fit data regarding torsional loads effects on growth. Mechanobiological data for humans is very scarce. For this reason, when possible, the model parameters values were estimated, for the proposed generic geometry, after growth measurements in animal models available in the literature. Although it is not possible to assert their validity for humans, the proposed model along with the obtained parameters values give a rational foundation to be used in more advanced computational studies.

Growth improvement following antiretroviral therapy initiation in children with perinatally-acquired HIV diagnosed in older childhood in Zimbabwe: a prospective cohort study

BACKGROUND

Children who initiate antiretroviral therapy (ART) before age 5 years can recover height and weight compared to uninfected peers, but growth outcomes are unknown for children initiating ART at older ages. We investigated factors associated with growth failure at ART initiation and modelled growth by age on ART.

METHODS

We conducted secondary analysis of cohort of children aged 6-15 years late-diagnosed with HIV in Harare, Zimbabwe, with entry at ART initiation in 2013-2015. Factors associated with height-for-age (HAZ), weight-for-age (WAZ) and BMI-for-age (BAZ) z-scores <- 2 (stunting, underweight and wasting respectively) at ART initiation were assessed using multivariable logistic regression. These outcomes were compared at ART initiation and 12 month follow-up using paired t-tests. HAZ and BAZ were modelled using restricted cubic splines.

RESULTS

Participants (N = 302; 51.6% female; median age 11 years) were followed for a median of 16.6 months (IQR 11.0-19.8). At ART initiation 34.8% were stunted, 34.5% underweight and 15.1% wasted. Stunting was associated with age ≥ 12 years, CD4 count < 200 cells/μl, tuberculosis (TB) history and history of hospitalisation. Underweight was associated with older age, male sex and TB history, and wasting was associated with older age, TB history and hospitalisation. One year post-initiation, t-tests showed increased WAZ (p = 0.007) and BAZ (p = 0.004), but no evidence of changed HAZ (p = 0.85). Modelling showed that HAZ and BAZ decreased in early adolescence for boys on ART, but not girls.

CONCLUSION

Stunting and underweight were prevalent at ART initiation among late-diagnosed children, and HAZ did not improve after 1 year. Adolescent boys with perinatally acquired HIV and late diagnosis are particularly at risk of growth failure in puberty.

ERα/β/DMP1 axis promotes trans-differentiation of chondrocytes to bone cells through GSK-3β/β-catenin pathway

Estrogen-induced premature closing of the growth plate in the long bones is a major cause of short stature after premature puberty. Recent studies have found that chondrocytes can directly trans-differentiate into osteoblasts in the process of endochondral bone formation, which indicates that cartilage formation and osteogenesis may be a continuous biological process. However, whether estrogen promotes the direct trans-differentiation of chondrocytes into osteoblasts remains largely unknown. Chondrocytes were treated with different concentrations of 17β-estradiol, and Alizarin Red staining and alkaline phosphatase activity assay were used to detected osteogenesis. Specific short hairpin RNA and tamoxifen were used to block the estrogen receptor (ER) pathway and osteogenic marker genes and downstream gene expression were detected using real-time quantitative polymerase chain reaction, western blot, and immunohistochemistry staining. The findings showed that 17β-estradiol promoted the chondrocyte osteogenesis in vitro, even at high concentrations. In addition, blocking of the ERα/β pathway inhibited the trans-differentiation of chondrocytes into osteogenic cells. Furthermore, we found that dentin matrix protein 1 (DMP1), which is a direct downstream molecular of ER, was involved in 17β-estradiol/ER pathway-regulated osteogenesis. As well, glycogen synthase kinase-3 beta (GSK-3β)/β-catenin signal pathway also participates in ERα/β/DMP1-regulated chondrocyte osteogenesis. The GSK-3β/β-catenin signal pathway was involved in ERα/β/DMP1-regulated chondrocyte osteogenesis. These findings suggest that ER/DMP1/GSK-3β/β-catenin plays a vital role in estrogen regulation of chondrocyte osteogenesis and provide a therapeutic target for short stature caused by epiphyseal fusion.

Differentiation of Induced Pluripotent Stem Cells Into Chondrocytes: Methods and Applications for Disease Modeling and Drug Discovery

Induced pluripotent stem cell (iPSC) technology allows pathomechanistic and therapeutic investigation of human heritable disorders affecting tissue types whose collection from patients is difficult or even impossible. Among them are cartilage diseases. Over the past decade, iPSC-chondrocyte disease models have been shown to exhibit several key aspects of known disease mechanisms. Concurrently, an increasing number of protocols to differentiate iPSCs into chondrocytes have been published, each with its respective (dis)advantages. In this review we provide a comprehensive overview of the different differentiation approaches, the hitherto described iPSC-chondrocyte disease models and mechanistic and/or therapeutic insights that have been derived from their investigation, and the current model limitations. Key lessons are that the most appropriate differentiation approach is dependent upon the cartilage disease under investigation and that further optimization is still required to recapitulate the in vivo cartilage. © 2022 American Society for Bone and Mineral Research (ASBMR).

gp130/STAT3 signaling is required for homeostatic proliferation and anabolism in postnatal growth plate and articular chondrocytes

Growth of long bones and vertebrae is maintained postnatally by a long-lasting pool of progenitor cells. Little is known about the molecular mechanisms that regulate the output and maintenance of the cells that give rise to mature cartilage. Here we demonstrate that postnatal chondrocyte-specific deletion of a transcription factor Stat3 results in severely reduced proliferation coupled with increased hypertrophy, growth plate fusion, stunting and signs of progressive dysfunction of the articular cartilage. This effect is dimorphic, with females more strongly affected than males. Chondrocyte-specific deletion of the IL-6 family cytokine receptor gp130, which activates Stat3, phenocopied Stat3-deletion; deletion of Lifr, one of many co-receptors that signals through gp130, resulted in a milder phenotype. These data define a molecular circuit that regulates chondrogenic cell maintenance and output and reveals a pivotal positive function of IL-6 family cytokines in the skeletal system with direct implications for skeletal development and regeneration.

Slipped capital femoral epiphysis with hypopituitarism in adults: A case report and literature review

RATIONALE

Slipped capital femoral epiphysis (SCFE) is a common disease in pediatric orthopedics. Most research on SCFE has focused on high-risk groups or the whole population, and studies focusing on adult SCFE patients are rare. In the present study, we report the case of an adult patient with SCFE.

PATIENT CONCERN

A 37-year-old man presented to our clinic with persistent pain that was poorly localized to both hips, groin regions, and thighs for more than 1 year.

DIAGNOSES

A bilateral hip X-ray examination was performed, and the femoral epiphyses were found to be unfused on both sides. Low levels of growth hormone (GH), insulin-like growth factor-1 (IGF-1), triiodothyronine (T3), thyroxine (T4), follicle-stimulating hormone, luteinizing hormone, estradiol, and testosterone, and high levels of thyroid-stimulating hormone, prolactin, and cortisol.

INTERVENTIONS

Hormone-substitution therapies (levothyroxine sodium to treat hypothyroidism and testosterone enanthate to treat hypogonadism) were prescribed. Total hip arthroplasty was performed to treat femoral epiphysis slippage.

OUTCOMES

After 6 months of postoperative follow-up, the patient's gait improved significantly, and bilateral hip pain was relieved.

LESSONS

When treating adults with SCFE, clinicians must be alert to endocrine disorders. Comprehensive imaging evaluation is crucial for the accurate diagnosis and selection of an appropriate treatment.

Heterozygosity of the major histocompatibility complex predicts later self-reported pubertal maturation in men

Individual variation in the age of pubertal onset is linked to physical and mental health, yet the factors underlying this variation are poorly understood. Life history theory predicts that individuals at higher risk of mortality due to extrinsic causes such as infectious disease should sexually mature and reproduce earlier, whereas those at lower risk can delay puberty and continue to invest resources in somatic growth. We examined relationships between a genetic predictor of infectious disease resistance, heterozygosity of the major histocompatibility complex (MHC), referred to as the human leukocyte antigen (HLA) gene in humans, and self-reported pubertal timing. In a combined sample of men from Canada (n = 137) and the United States (n = 43), MHC heterozygosity predicted later self-reported pubertal development. These findings suggest a genetic trade-off between immunocompetence and sexual maturation in human males.

Impact of early hypothalamic-pituitary-gonadal axis maturation on prostate cancer: cross-sectional analysis of a Veterans affairs cohort

Background

It has been hypothesized that earlier onset of puberty, and thus a more prolonged exposure to high androgen levels, increases risk of prostate cancer development. Our objective was to determine whether earlier age of first shave and height, as surrogates of pubertal onset, were associated with risk of prostate cancer diagnosis.

Methods

A prospectively collected outcomes registry of patients presenting for a prostate biopsy at the Charlie Norwood Veterans Affair Medical Center in Augusta, GA between July 1995 and June 2016 was utilized. The associations between age of first shave and height, each, and risks of a positive prostate biopsy, high grade cancer, and high volume disease were evaluated using univariable and multivariable logistic regression analysis, controlling for baseline patient demographic and oncologic characteristics.

Results

Our cohort included 2,456 patients. Biopsies were positive in 1,257 (51.2%) patients, of whom 293 (23.3%) and 407 (32.4%) had high grade and volume disease, respectively. Median age of first shave was 17.0 years (interquartile range 16.0–19.0) and height was 177.7 cm (172.8–182.9). On multivariable analysis, later of age of first shave was significantly associated with increased odds of a positive prostate biopsy (odds ratio for >18 versus <16 years: 5.34, P=0.02) and taller patients had significantly increased odds of high grade cancer (odds ratio for 175–180 versus <175 cm: 7.46, P=0.037).

Conclusions

Amongst patients presenting for a prostate biopsy, those with a later age of first shave and taller height have an increased risk of a positive prostate biopsy and high grade prostate cancer, respectively.

Impairment of Cyclo-oxygenase-2 Function Results in Abnormal Growth Plate Development and Bone Microarchitecture but Does Not Affect Longitudinal Growth of the Long Bones in Skeletally Immature Mice

OBJECTIVE

Despite the general awareness that cyclo-oxygenase-2 (COX-2) is crucial for endochondral ossification, the role of COX-2 in skeletal development is largely unknown. We hypothesized that inhibition or genetic loss of COX-2 leads to impaired growth plate development and consequently impaired postnatal development of the long bones.

DESIGN

Skeletally immature (5 weeks old) B6;129S-Ptgs2^tm1Jed/J wildtype mice were treated for 10 weeks with celecoxib (daily oral administration 10 mg/kg) or placebo and compared with B6;129S-Ptgs2^tm1Jed/J homozygous knockout mice (n = 12 per group).

RESULTS

Fifteen weeks postnatally, no significant difference in growth plate (zone) thickness was found between groups. However, significantly higher proteoglycan content and lower expression levels of collagen type II and X staining in the growth plates of celecoxib-treated mice, and to a lesser extent in COX-2 knockout mice. In addition, a significantly decreased cell number and cell size were observed in the hypertrophic zone of the growth plates of both experimental groups. Micro-computed tomography analysis of the subchondral bone region directly beneath the growth plate showed significantly higher bone density and trabecular thickness, following celecoxib treatment. Despite the detected differences in growth plate extracellular matrix composition and subchondral bone morphology, no difference was found in the length of the tibia in celecoxib-treated mice or COX-2 knockout mice.

CONCLUSIONS

Genetic loss of COX-2 or treatment with celecoxib did not result in detectable differences in gross murine formation of the tibia or femur. However, there were notable phenotypic features detected in the maturation of the growth plate (hypertrophic zone and subchondral bone) as a result of the celecoxib treatment.

Treatment of Short Stature with Aromatase Inhibitors: A Systematic Review and Meta-Analysis

The objective of the study is to determine the risks and benefits of treating idiopathic short stature (ISS) with aromatase inhibitors (AIs). We comprehensively searched PubMed, Embase, and the China National Knowledge Infrastructure between establishment year and January 31, 2020. Mean difference (MD)/Standardized mean differences (SMD) with 95% confidence intervals (CI) of individual studies were pooled using fixed or random effects models. Subgroup and sensitivity analyses were also performed. Publication bias was estimated using funnel plots and Egger tests. Fourteen studies including 388 participants were included. The meta-analysis results showed that AIs significantly increased final height (MD=2.46, 95% CI: 0.8-4.12) and predicted adult height (MD=0.34, 95% CI: 0.11-0.57). Changes in bone age (MD=-0.1, 95% CI: -0.86-0.66) and bone mineral density (MD=-0.05, 95% CI: -0.19-0.1) were not different between intervention and control group. AI significantly increased testosterone level (SMD=2.01, 95% CI: 0.8-3.23) and reduced estradiol level (SMD=-1.13, 95% CI: -1.87 to -0.40); The intervention and control group had no significant differences in the levels of high-density lipoprotein-cholesterol (SMD=-0.31, 95%CI: -0.68-0.06) and IGF-1 (SMD=0.7, 95% CI: -0.66-2.06) levels. Adverse events were more frequent in the intervention group than in the control group (odds ratio=3.12, 95% CI: 1.44-6.73). In conclusion, both AI monotherapy and AI combination therapy can increase predicted adult height and testosterone levels.

A collagen extraction and deuterium oxide stable isotope tracer method for the quantification of bone collagen synthesis rates in vivo

The development of safe and practical strategies to prevent weakening of bone tissue is vital, yet attempts to achieve this have been hindered by a lack of understanding of the short-term (days-weeks) physiology of bone collagen turnover. To address this, we have developed a method to quantify bone collagen synthesis in vivo, using deuterium oxide (D₂ O) tracer incorporation techniques combined with gas chromatography pyrolysis isotope-ratio mass spectrometry (GC-pyrolysis-IRMS). Forty-six male and female rats from a selectively bred model ingested D₂ O for 3 weeks. Femur diaphyses (FEM), tibia proximal (T-PRO), and distal (T-DIS) epiphyses-metaphyses and tibia mid-shaft diaphyses (T-MID) were obtained from all rats after necropsy. After demineralisation, collagen proteins were isolated and hydrolysed and collagen fractional synthetic rates (FSRs) determined by incorporation of deuterium into protein-bound alanine via GC-pyrolysis-IRMS. The collagen FSR for the FEM (0.131 ± 0.078%/day; 95% CI [0.106-0.156]) was greater than the FSR at T-MID (0.055 ± 0.049%/day; 95% CI [0.040-0.070]; p < 0.001). The T-PRO site had the highest FSR (0.203 ± 0.123%/day; 95% CI [0.166-0.241]) and T-DIS the lowest (0.027 ± 0.015%/day; 95% CI [0.022-0.031]). The three tibial sites exhibited different FSRs (p < 0.001). Herein, we have developed a sensitive method to quantify in vivo bone collagen synthesis and identified site-specific rates of synthesis, which could be applicable to studies of human bone collagen turnover.

Physical deviation and precocious puberty among school-aged children in Leshan City: an investigative study

Objective

We investigated physical deviation and precocious puberty among school-aged children in Leshan City, to provide a theoretical basis for the management of precocious puberty in children.

Methods

We selected 12 primary schools of Leshan City using a cluster random sampling method and conducted physical examinations among healthy students aged 4 12 years. A total of 11,000 students were recruited (5502 boys and 5498 girls). We measured body mass index (BMI), and participants were tested for precocious puberty according to the Tanner stages and standard maps. Nutritional status was also evaluated.

Results

Obese and overweight children accounted for a high proportion of participants; the prevalence of underweight was the lowest. The prevalence of obesity among boys was higher than that in girls. Precocious puberty was mainly observed in girls, particularly those age 7 years old. The prevalence of precocious puberty among overweight and obese children was higher than that in children with normal weight.

Conclusion

We identified a significant sex difference in precocious puberty among children in Leshan City. Overweight and obesity may be associated with precocious puberty.

The NIMH Intramural Longitudinal Study of the Endocrine and Neurobiological Events Accompanying Puberty: Protocol and rationale for methods and measures

Delineating the relationship between human neurodevelopment and the maturation of the hypothalamic-pituitary-gonadal (HPG) axis during puberty is critical for investigating the increase in vulnerability to neuropsychiatric disorders that is well documented during this period. Preclinical research demonstrates a clear association between gonadal production of sex steroids and neurodevelopment; however, identifying similar associations in humans has been complicated by confounding variables (such as age) and the coactivation of two additional endocrine systems (the adrenal androgenic system and the somatotropic growth axis) and requires further elucidation. In this paper, we present the design of, and preliminary observations from, the ongoing NIMH Intramural Longitudinal Study of the Endocrine and Neurobiological Events Accompanying Puberty. The aim of this study is to directly examine how the increase in sex steroid hormone production following activation of the HPG-axis (i.e., gonadarche) impacts neurodevelopment, and, additionally, to determine how gonadal development and maturation is associated with longitudinal changes in brain structure and function in boys and girls. To disentangle the effects of sex steroids from those of age and other endocrine events on brain development, our study design includes 1) selection criteria that establish a well-characterized baseline cohort of healthy 8-year-old children prior to the onset of puberty (e.g., prior to puberty-related sex steroid hormone production); 2) temporally dense longitudinal, repeated-measures sampling of typically developing children at 8-10 month intervals over a 10-year period between the ages of eight and 18; 3) contemporaneous collection of endocrine and other measures of gonadal, adrenal, and growth axis function at each timepoint; and 4) collection of multimodal neuroimaging measures at these same timepoints, including brain structure (gray and white matter volume, cortical thickness and area, white matter integrity, myelination) and function (reward processing, emotional processing, inhibition/impulsivity, working memory, resting-state network connectivity, regional cerebral blood flow). This report of our ongoing longitudinal study 1) provides a comprehensive review of the endocrine events of puberty; 2) details our overall study design; 3) presents our selection criteria for study entry (e.g., well-characterized prepubertal baseline) along with the endocrinological considerations and guiding principles that underlie these criteria; 4) describes our longitudinal outcome measures and how they specifically relate to investigating the effects of gonadal development on brain development; and 5) documents patterns of fMRI activation and resting-state networks from an early, representative subsample of our cohort of prepubertal 8-year-old children.

Evaluation of impaired growth plate development of long bones in skeletally immature mice by antirheumatic agents

Restriction of physical growth and development is a known problem in patients with juvenile idiopathic arthritis (JIA). However, the effect of medical treatment for JIA on skeletal growth in affected children has not been properly investigated. We, therefore, hypothesize that naproxen and methotrexate (MTX) affect endochondral ossification and will lead to reduced skeletal development. Treatment of ATDC5 cells, an in vitro model for endochondral ossification, with naproxen or MTX resulted in increased chondrogenic but decreased hypertrophic differentiation. In vivo, healthy growing C57BL/6 mice were treated with naproxen, MTX, or placebo for 10 weeks. At 15 weeks postnatal, both the length of the tibia and the length of the femur were significantly reduced in the naproxen- and MTX-treated mice compared to their controls. Growth plate analysis revealed a significantly thicker proliferative zone, while the hypertrophic zone was significantly thinner in both experimental groups compared to their controls, comparable to the in vitro results. Micro-computed tomography analysis of the subchondral bone region directly below the growth disc showed significantly altered bone microarchitecture in naproxen and MTX groups. In addition, the involvement of the PTHrP-Ihh loop in naproxen- and MTX-treated cells was shown. Overall, these results demonstrate that naproxen and MTX have a profound effect on endochondral ossification during growth plate development, abnormal subchondral bone morphology, and reduced bone length. A better understanding of how medication influences the development of the growth plate will improve understanding of endochondral ossification and reveal possibilities to improve the treatment of pediatric patients.

The Neonatal and Juvenile Pig in Pediatric Drug Discovery and Development

Pharmacotherapy in pediatric patients is challenging in view of the maturation of organ systems and processes that affect pharmacokinetics and pharmacodynamics. Especially for the youngest age groups and for pediatric-only indications, neonatal and juvenile animal models can be useful to assess drug safety and to better understand the mechanisms of diseases or conditions. In this respect, the use of neonatal and juvenile pigs in the field of pediatric drug discovery and development is promising, although still limited at this point. This review summarizes the comparative postnatal development of pigs and humans and discusses the advantages of the juvenile pig in view of developmental pharmacology, pediatric diseases, drug discovery and drug safety testing. Furthermore, limitations and unexplored aspects of this large animal model are covered. At this point in time, the potential of the neonatal and juvenile pig as nonclinical safety models for pediatric drug development is underexplored.

Bone tissue morphology of rat offspring lactationally exposed to polychlorinated biphenyl 169 and 155

Polychlorinated biphenyls (PCBs) are ubiquitous, persistent, organic pollutants also considered endocrine-disrupting chemicals. Our study examined the effects of lactational exposure to nondioxin-like PCB-155 and/or dioxin-like PCB-169 on longitudinal femur growth at the distal epiphyseal growth plate (EGP) in young rats at three different ages [postnatal days (PNDs) 9, 22, and 42]. After delivery, lactating rats were divided into four groups (PCB-169, PCB-155, PCB-155 + 169, and control) and administered PCBs intraperitoneally. The femurs of offspring were used to estimate growth rate (µm/day), and histomorphometric analysis on the distal femur included the thickness of the EGP and zones of proliferation and hypertrophy with calcification. Stereometry was used to determine trabecular bone volume density. In the PCB-169 and PCB-155 + 169 groups, PCB-169 affected longitudinal bone growth in the early postnatal period by interfering with chondrocytes in the EGP zone of proliferation and, to a lesser extent, the zone of hypertrophy. Morphometric alterations in EGP structure diminished until puberty. A slow growth rate persisted in the PCB-169 group until PND 42, while in the PCB-155 group, a fast growth rate between PNDs 9 to 22 was significantly reduced between PNDs 22 to 42. Sterometric assessment showed decreased trabecular bone volume in the PCB-155 + 169 group compared with that in the control on PND 9 and increased in the PCB-169 group compared with that in the PCB-155 group on PND 42. To summarize, studied PCB congeners exerted congener- and age-dependent effects on femur growth rate and its histomorphometric characteristics.

The current outcomes and future challenges in pediatric vascularized composite allotransplantation

PURPOSE OF REVIEW

We review the outcomes and future challenges associated with pediatric vascularized composite allotransplantation, including follow-up data from our bilateral pediatric hand-forearm transplantation.

RECENT FINDINGS

In 2015, the first heterologous pediatric upper extremity hand-forearm transplant was performed at the Children's Hospital of Philadelphia, and in 2019, the first pediatric neck reconstructive transplantation was performed in Poland. The 5-year follow-up of the pediatric upper extremity recipient demonstrates similar growth rates bilaterally, an increase in bone age parallel to chronologic age, and perhaps similar overall growth to nontransplant norms. The pediatric upper extremity recipient continues to make gains in functional independence. He excels academically and participates in various extracurricular activities. Future challenges unique to the pediatric population include ethical issues of informed consent, psychosocial implications, limited donor pool, posttransplant compliance issues, and greater life expectancy and therefore time to inherit the many complications of immunosuppression.

SUMMARY

Currently, we recommend pediatric vascularized composite allotransplantation (VCA) for bilateral upper extremity amputees, preferably on immunosuppression already, and those patients who would have the most potential gain not available through standard reconstructive techniques while being able to comply with postoperative immunosuppression protocols, surveillance, rehabilitation, and follow-up.

The growth plate: a physiologic overview

The growth plate is the cartilaginous portion of long bones where the longitudinal growth of the bone takes place. Its structure comprises chondrocytes suspended in a collagen matrix that go through several stages of maturation until they finally die, and are replaced by osteoblasts, osteoclasts, and lamellar bone.The process of endochondral ossification is coordinated by chondrocytes and a variety of humoral factors including growth hormone, parathyroid hormone, oestrogen, growth factors, cytokines, and various signalling pathways.Chondrocytes progress from a resting state to enter the phases of proliferation and hypertrophy. Under the influence of oestrogen, the proliferation of chondrocytes decreases as the resting chondrocytes are consumed. During the terminal phase of differentiation, cartilage is replaced by blood vessels and organized bone tissue, and once chondrocytes have died, the longitudinal growth of the bone ceases and the growth plate closes.The highly complex regulatory signals involved in this process are genetically determined, and genetic perturbations in any of the associated genes can result in abnormalities of bone growth. Hundreds of chondrodysplasias have been described, pointing to the complexity of the humoral control systems involved in endochondral ossification.While our knowledge of the mechanisms behind the various bone growth control systems is improving, a deeper understanding of the underlying processes could aid clinicians to better understand bone health and bone growth abnormalities. This review describes the current clinical research into the physiology of the growth plate. Cite this article: EFORT Open Rev 2020;5:498-507. DOI: 10.1302/2058-5241.5.190088.

Biochemical and histopathologic assessment of effects of acitretin on epiphyseal growth plate in rats

Introduction

Acitretin is a commonly used retinoid in dermatology. Although there are generally known side effects, the effects on the epiphyseal plaque and bone metabolism are not clear in the literature.

Aim

To histopathologically investigate the effects on the epiphyseal plate and assess variations in bone metabolism caused by acitretin.

Material and methods

Three groups were formed with 10 rats in each group. The 1^st group (n = 10, 5 male, 5 female) were administered 10 mg/kg/day oral acitretin solution and the 2^nd group (n = 10, 5 male, 5 female) were administered 3 mg/kg/day oral acitretin solution. The control group were given normal standard feed and water. Rats were sacrificed at the end of 4 weeks. The proximal tibias were excised and histopathologically and immunohistochemically assessed. Biochemical assessment was also carried out.

Results

Staining with haematoxylin-eosin found reductions in the epiphyseal plate in the 1^st and 2^nd group compared to the control group, though this situation was not statistically significant. Immunohistochemical studies did not encounter Type II collagen in the epiphyseal bone, proliferative zone and hypertrophic zone in the control group, low dose acitretin solution group and high dose acitretin solution group. Type II collagen was not observed in osteoids and osteoblasts. Type I collagen was not observed in the hypertrophic zone and proliferative zone of any group.

Conclusions

Our data show that though acitretin caused degeneration of the epiphyseal plate, it did not cause clear thinning and we identified no significant variations in bone metabolism markers.

Valproic Acid Impacts the Growth of Growth Plate Chondrocytes

A range of bone abnormalities including short stature have been reported to be associated with the use of antiepileptic drugs (AEDs) in children. Exactly how AEDs impact skeletal growth, however, is not clear. In the present study, rat growth plate chondrocytes were cultured to study the effects of AEDs, including valproic acid (VPA), oxcarbazepine (OXA), levetiracetam (LEV), lamotrigine (LTG), and topiramate (TPM) on the skeletal growth. VPA markedly reduced the number of chondrocytes by apoptosiswhile other AEDs had no effect. The apoptosis associated noncleaved and cleaved caspase 3, and caspases were increased by exposure to VPA, which up-regulated cyclooxygenase 2 (COX-2) mRNA and protein levels likely through histone acetylation. The COX-2 inhibitor NS-398 attenuated the effects of VPA up-regulating COX-2 expression and decreased VPA-induced caspase 3 expression. The use of VPA in children should be closely monitored or replaced, where appropriate, by AEDs which do not apparently affect the growth plate chondrocytes.

The impact of residual growth on deformity progression

Idiopathic scoliosis is a disease of the growing spine. Risk of progression and aggravation of disease are mainly dictated by the remaining growth and curve magnitude. Remaining growth can be estimated by repeated biometric measurements, tanner sign and bone age estimation. Puberty is the turning point in the natural history of this disease. The first two years following puberty are the turning point in the natural history of this disease since 90% of growth occurs during this period. Lateral olecranon radiograph is effective for estimating bone age during this phase. Growth acceleration is followed by a deceleration phase of three years where menarche occurs. Bone age during this phase is evaluated by hand X-rays and the Risser sign. Progression risk assessment of idiopathic scoliosis showed that a 30° curve at the beginning of puberty together with 20° to 30° curves with more than 10° of annual curve progression has a 100% risk of progression towards the 45° surgical threshold. In these patients, anticipation may be the key for effective treatment strategy. Treating these curves earlier than the surgical threshold before increased stiffness would lead to a better outcome.

Should We Make More Bone or Not, As Told by Kisspeptin Neurons in the Arcuate Nucleus

Since its initial discovery in 2002, the neuropeptide Kisspeptin (Kiss1) has been anointed as the master regulator controlling the onset of puberty in males and females. Over the last several years, multiple groups found that Kiss1 signaling is mediated by the 7TM surface receptor GPCR54. Kiss1 mRNA is highly enriched in the basal medial and lateral subregions of the arcuate nucleus (ARC) in the medial basal hypothalamus. Thus, Kiss1^ARC neurons reside in a unique anatomical location ideal for sensing and responding to circulating steroid hormones as well as nutrients. Kiss1 expression is highly responsive to fluctuations of the gonadal hormone, estrogen, with nearly 90% of Kiss1^ARC neurons expressing the nuclear hormone estrogen receptor alpha (ERa). Here we review recent research that extends the function of Kiss1ARC neurons beyond the regulation of puberty and highlight their emerging, novel roles in controlling energy allocation, behavioral outputs, and sex-dependent bone remodeling in females. Indeed, some of these previously unknown functions for Kiss1 neurons are quite striking as exemplified by the remarkable increase in bone mass after manipulating estrogen signaling in Kiss1^ARC neurons. Taken together, we suggest that Kiss1^ARC neurons are highly sensitive to nutritional and hormonal cues that dictate energy utilization and reproduction.

Body Size and Tissue-Scaling Is Regulated by Motoneuron-Derived Activinß in Drosophila melanogaster

Correct scaling of body and organ size is crucial for proper development, and the survival of all organisms. Perturbations in circulating hormones, including insulins and steroids, are largely responsible for changing body size in response to both genetic and environmental factors. Such perturbations typically produce adults whose organs and appendages scale proportionately with final size. The identity of additional factors that might contribute to scaling of organs and appendages with body size is unknown. Here, we report that loss-of-function mutations in DrosophilaActivinβ (Actβ), a member of the TGF-β superfamily, lead to the production of small larvae/pupae and undersized rare adult escapers. Morphometric measurements of escaper adult appendage size (wings and legs), as well as heads, thoraxes, and abdomens, reveal a disproportional reduction in abdominal size compared to other tissues. Similar size measurements of selected Actβ mutant larval tissues demonstrate that somatic muscle size is disproportionately smaller when compared to the fat body, salivary glands, prothoracic glands, imaginal discs, and brain. We also show that Actβ control of body size is dependent on canonical signaling through the transcription-factor dSmad2 and that it modulates the growth rate, but not feeding behavior, during the third-instar period. Tissue- and cell-specific knockdown, and overexpression studies, reveal that motoneuron-derived Actβ is essential for regulating proper body size and tissue scaling. These studies suggest that, unlike in vertebrates, where Myostatin and certain other Activin-like factors act as systemic negative regulators of muscle mass, in Drosophila, Actβ is a positive regulator of muscle mass that is directly delivered to muscles by motoneurons. We discuss the importance of these findings in coordinating proportional scaling of insect muscle mass to appendage size.

[Clinical effect of letrozole in treatment of idiopathic short stature in adolescent boys]

OBJECTIVE

To evaluate the therapeutic effect and safety of letrozole in the treatment of adolescent boys with idiopathic short stature (ISS).

METHODS

A retrospective analysis was performed for the clinical data of 16 adolescent boys with ISS who had a bone age of ≥14 years. Among these boys, 8 were initially treated with recombinant human growth hormone (rhGH), followed by rhGH combined with letrozole during a bone age of 14-15.5 years. The other 8 boys were initially treated with rhGH combined with letrozole since their bone age was ≥14 years at diagnosis. Of the 16 boys, 16 were treated for not less than 6 months, 12 were treated for not less than 1 year, and 5 were treated for not less than 1.5 years. The increase in bone age, predicted adult height (PAH), final adult height, sex hormones, and adverse reactions after treatment were analyzed.

RESULTS

After 6 months, 1 year, and 1.5 years of treatment, median bone age was increased by 0 year, 0.5 year, and 0.5 year respectively, which was significantly lower than the increase in age (P<0.05). There was a significant increase in PAH after treatment (P<0.05). Seven boys reached final height, which was significantly higher than PAH before treatment (P<0.05). All the 16 boys had significant increases in luteinizing hormone, follicle-stimulating hormone, and testosterone levels after treatment (P<0.05), with a significant reduction in the estradiol level and a significant increase in the insulin level at 1 year of treatment (P<0.05). There was a significant increase in the insulin-like growth factor-1 level at 6 months and 1 year of treatment (P<0.05). There were no significant changes in blood glucose, blood lipids, uric acid, and the three indices for thyroid function as monitored during treatment (P>0.05).

CONCLUSIONS

In adolescent boys with ISS and a high bone age, rhGH combined with letrozole can safely and effectively delay the increase in bone age and improve PAH and final adult height, with little adverse effect.

[Clinical effect of letrozole in treatment of idiopathic short stature in adolescent boys]

OBJECTIVE

To evaluate the therapeutic effect and safety of letrozole in the treatment of adolescent boys with idiopathic short stature (ISS).

METHODS

A retrospective analysis was performed for the clinical data of 16 adolescent boys with ISS who had a bone age of ≥14 years. Among these boys, 8 were initially treated with recombinant human growth hormone (rhGH), followed by rhGH combined with letrozole during a bone age of 14-15.5 years. The other 8 boys were initially treated with rhGH combined with letrozole since their bone age was ≥14 years at diagnosis. Of the 16 boys, 16 were treated for not less than 6 months, 12 were treated for not less than 1 year, and 5 were treated for not less than 1.5 years. The increase in bone age, predicted adult height (PAH), final adult height, sex hormones, and adverse reactions after treatment were analyzed.

RESULTS

After 6 months, 1 year, and 1.5 years of treatment, median bone age was increased by 0 year, 0.5 year, and 0.5 year respectively, which was significantly lower than the increase in age (P<0.05). There was a significant increase in PAH after treatment (P<0.05). Seven boys reached final height, which was significantly higher than PAH before treatment (P<0.05). All the 16 boys had significant increases in luteinizing hormone, follicle-stimulating hormone, and testosterone levels after treatment (P<0.05), with a significant reduction in the estradiol level and a significant increase in the insulin level at 1 year of treatment (P<0.05). There was a significant increase in the insulin-like growth factor-1 level at 6 months and 1 year of treatment (P<0.05). There were no significant changes in blood glucose, blood lipids, uric acid, and the three indices for thyroid function as monitored during treatment (P>0.05).

CONCLUSIONS

In adolescent boys with ISS and a high bone age, rhGH combined with letrozole can safely and effectively delay the increase in bone age and improve PAH and final adult height, with little adverse effect.

Quality of Life in Adolescent Boys with Idiopathic Short Stature: Positive Impact of Growth Hormone and Aromatase Inhibitors

BACKGROUND

The combination of growth hormone (GH) and aromatase inhibitors (AI) improves linear growth in severely short adolescent boys; however, the effects of this intervention on quality of life (QoL) are unknown. This study assesses whether GH, AI, or their combination impacts the QoL of adolescent males with idiopathic short stature (ISS) from both the adolescent and the parent perspective.

METHOD

A randomized open-label comparator trial was conducted in 76 pubertal males with ISS who received AI, GH, or AI/GH for 24 months. The condition-specific Quality of Life in Short Stature Youth questionnaire was used to assess QoL.

RESULTS

QoL scores were low at baseline in the children's and parents' reports. Within-group testing showed that total QoL scores increased significantly at 24 months in the GH and AI/GH group but not the AI group in the children's report, whereas it increased in all of the groups in the parents' report. Increases in QoL scores were associated with an increase in height SDS.

CONCLUSIONS

Treatment with GH and AI/GH was associated with improved QoL scores as measured from both the patients' and the parents' perspectives, suggesting that the improved growth resulting from the use of these growth-promoting therapies has beneficial psychosocial effects in adolescent males with ISS followed for 24 months.

Early menarche is associated with lower adult lung function: A longitudinal cohort study from the first to sixth decade of life

BACKGROUND AND OBJECTIVE

Early menarche is increasing in prevalence worldwide, prompting clinical and public health interest on its links with pulmonary function. We aimed to investigate the relationship between early menarche and lung function in middle age.

METHODS

The population-based Tasmanian Longitudinal Health Study (born 1961; n = 8583), was initiated in 1968. The 5th Decade follow-up data (mean age: 45 years) included age at menarche and complex lung function testing. The 6th Decade follow-up (age: 53 years) repeated spirometry and gas transfer factor. Multiple linear regression and mediation analyses were performed to determine the association between age at menarche and adult lung function and investigate biological pathways, including the proportion mediated by adult-attained height.

RESULTS

Girls reporting an early menarche (<12 years) were measured to be taller with greater lung function at age 7 years compared with those reporting menarche ≥12 years. By 45 years of age, they were shorter and had lower post-bronchodilator (BD) forced expiratory volume in 1 s (adjusted mean difference: -133 mL; 95% CI: -233, -33), forced vital capacity (-183 mL; 95% CI: -300, -65) and functional residual capacity (-168 mL; 95% CI: -315, -21). Magnitudes of spirometric deficits were similar at age 53 years. Forty percent of these total effects were mediated through adult-attained height.

CONCLUSION

Early menarche was associated with reduced adult lung function. This is the first study to investigate post-BD outcomes and quantify the partial role of adult height in this association.

Puberty: Normal physiology (brief overview)

Puberty is a defining phase of human development where growth ends and the ability to reproduce begins. An understanding of the events leading up to puberty highlights the fact that this is the culmination of a process of skeletal and gonadal activity that has been ongoing since conception. Although there is natural variation in the timing of events in and around puberty the basic underlying processes are common to all healthy human beings. This chapter is intended to outline the mechanisms underlying normal growth and development before and during puberty. By understanding normality the pathological processes that give rise to abnormalities of pubertal development can be understood more easily.

Human cytochrome P450 enzymes 5-51 as targets of drugs and natural and environmental compounds: mechanisms, induction, and inhibition - toxic effects and benefits

Cytochrome P450 (P450, CYP) enzymes have long been of interest due to their roles in the metabolism of drugs, pesticides, pro-carcinogens, and other xenobiotic chemicals. They have also been of interest due to their very critical roles in the biosynthesis and metabolism of steroids, vitamins, and certain eicosanoids. This review covers the 22 (of the total of 57) human P450s in Families 5-51 and their substrate selectivity. Furthermore, included is information and references regarding inducibility, inhibition, and (in some cases) stimulation by chemicals. We update and discuss important aspects of each of these 22 P450s and questions that remain open.

Age at Menarche and Blood Pressure in Pregnancy

Objectives

To investigate whether age at menarche is related to maternal blood pressure in pregnancy and, if so, whether obesity and insulin resistance can modify the associations.

Study Design

Analysis of data collected from 438 pregnant women from the longitudinal and prospective Cambridge Baby Growth Study.

Main Outcome

Testing associations between questionnaire-derived age at menarche and blood pressure measurements in pregnancy collected from hospital notes, and investigating whether any associations were altered by maternal pre-pregnancy body mass index (BMI) and insulin resistance.

Measures

Mean arterial blood pressure at four time points across pregnancy, age at menarche, (Homeostasis Model Assessment) insulin resistance around week 28 of pregnancy.

Results

For each increased year in age at menarche there was a drop in mean arterial blood pressure (mmHg) of 0.6 at 11.9 weeks, 0.9 at 31.4 and 37.0 weeks, and 0.4 at 38.8 weeks (a maximal difference of over 7 mmHg across extremes of AAM). Each association was attenuated by both maternal pre-pregnancy BMI and insulin resistance.

Conclusions

Age at menarche is negatively associated with future blood pressure in pregnancy, so those with the earliest age at menarche have the highest blood pressures. Either these associations may be mediated by links between age at menarche and obesity/insulin resistance, or there may be a confounder (e.g. systemic inflammation) that links age at menarche to each of them.

Postnatal ex vivo rat model for longitudinal bone growth investigations

BACKGROUND

Chondrocytes in the growth plate (GP) undergo increases in volume during different cascades of cell differentiation during longitudinal bone growth. The volume increase is reported to be the most significant variable in understanding the mechanism of long bone growth.

METHODS

Forty-five postnatal Sprague-Dawley rat pups, 7-15 days old were divided into nine age groups (P7-P15). Five pups were allocated to each group. The rats were sacrificed and tibia and metatarsal bones were harvested. Bone lengths were measured after 0, 24, 48, and 72 hours of ex vivo incubation. Histology of bones was carried out, and GP lengths and chondrocyte densities were determined.

RESULTS

There were significant differences in bone length among the age groups after 0 and 72 hours of incubation. Histological sectioning was possible in metatarsal bone from all age groups, and in tibia from 7- to 13-day-old rats. No significant differences in tibia and metatarsal GP lengths were seen among different age groups at 0 and 72 hours of incubation. Significant differences in chondrocyte densities along the epiphyseal GP of the bones between 0 and 72 hours of incubation were observed in most of the age groups.

CONCLUSION

Ex vivo growth of tibia and metatarsal bones of rats aged 7-15 days old is possible, with percentage growth rates of 23.87 ± 0.80% and 40.38 ± 0.95% measured in tibia and metatarsal bone, respectively. Histological sectioning of bones was carried out without the need for decalcification in P7-P13 tibia and P7-P15 metatarsal bone. Increases in chondrocyte density along the GP influence overall bone elongation.

Reduced body size of insular black-tailed deer is caused by slowed development

Adult body size correlates strongly with fitness, but mean body sizes frequently differ among conspecific populations. Ultimate, fitness-based explanations for these deviations in animals typically focus on community-level or physiological processes (e.g., competition, thermoregulation). However, proximate mechanisms underlying adaptive body size adjustments remain poorly understood. Adjustments in adult body size may result from shifts in growth-related life-history traits, such as the length of time to achieve adult body size (i.e., growth period) and how quickly the body increases in size (i.e., growth rate). Since insular populations often demonstrate dramatic shifts in adult body size, island populations represent a natural experiment by which to test the proximate mechanisms of size change. Here, using dental eruption patterns, we show that a dwarfed population of black-tailed deer (Odocoileus hemionus columbianus) experiences significant heterochronic shifts relative to mainland conspecifics. Namely, juvenile development slowed, such that teeth erupted ≥ 1 year later, but cranial growth suggested no concurrent adjustments in skeletal growth period. Thus, slowed growth rate, shown here with teeth, combined with unchanged growth period resulted in dwarfism, consistent with ultimate predictions for insular, resource-limited populations. Therefore, selection on body size may act on life-history traits that influence body size, rather than acting on body size directly.

Limb- and tendon-specific Adamtsl2 deletion identifies a role for ADAMTSL2 in tendon growth in a mouse model for geleophysic dysplasia

Geleophysic dysplasia is a rare, frequently lethal condition characterized by severe short stature with progressive joint contractures, cardiac, pulmonary, and skin anomalies. Geleophysic dysplasia results from dominant fibrillin-1 (FBN1) or recessive ADAMTSL2 mutations, suggesting a functional link between ADAMTSL2 and fibrillin microfibrils. Mice lacking ADAMTSL2 die at birth, which has precluded analysis of postnatal limb development and mechanisms underlying the skeletal anomalies of geleophysic dysplasia. Here, detailed expression analysis of Adamtsl2 using an intragenic lacZ reporter shows strong Adamtsl2 expression in limb tendons. Expression in developing and growing bones is present in regions that are destined to become articular cartilage but is absent in growth plate cartilage. Consistent with strong tendon expression, Adamtsl2 conditional deletion in limb mesenchyme using Prx1-Cre led to tendon anomalies, albeit with normal collagen fibrils, and distal limb shortening, providing a mouse model for geleophysic dysplasia. Unexpectedly, conditional Adamtsl2 deletion using Scx-Cre, a tendon-specific Cre-deleter strain, which does not delete in cartilage, also impaired skeletal growth. Recombinant ADAMTSL2 is shown here to colocalize with fibrillin microfibrils in vitro, and enhanced staining of fibrillin-1 microfibrils was observed in Prx1-Cre Adamtsl2 tendons. The findings show that ADAMTSL2 specifically regulates microfibril assembly in tendons and that proper microfibril composition in tendons is necessary for tendon growth. We speculate that reduced bone growth in geleophysic dysplasia may result from external tethering by short tendons rather than intrinsic growth plate anomalies. Taken together with previous work, we suggest that GD results from abnormal microfibril assembly in tissues, and that ADAMTSL2 may limit the assembly of fibrillin microfibrils.