Silastic Implants Research Articles

Systematic Review and Meta-Analysis of Outcomes in Type 1 Thyroplasty Comparing Silastic to Gore-Tex.

Type 1 Thyroplasty is a well-established procedure used for medializing an immobile vocal fold. Silastic and Gore-Tex are the two most common materials used to accomplish this, but comparative data on their relative efficacy are scarce. We sought to compare outcomes between Silastic and Gore-Tex implants via systematic review and meta-analysis for unilateral vocal fold immobility. We collected available data from PubMed, Embase, and Web of Science on demographics, maximum phonation time (MPT), voice handicap index (VHI-10/30) score, and any other relevant metrics encountered before comparatively evaluating differences in outcomes. The search yielded 1,534 records with 55 manuscripts ultimately included. There were 41 unique studies that utilized Silastic for a total of 1038 patients. There were 13 unique studies that utilized Gore-Tex for a total of 245 patients. The pooled mean increase in MPT for Silastic patients was 7.8 s (+1.3 SMD) compared with 5.7 s for Gore-Tex (+1.6 SMD). There was significant publication bias present in both analyses. The pooled mean change in VHI-30 with Silastic was -45.4 (62.2%, -2.09 SMD) compared with -51.6 (73.5%, -1.1 SMD) with Gore-Tex. The pooled mean change in VHI-10 with Silastic was -15.6 (54%, -0.46 SMD) compared with -11.6 (43%, -0.86 SMD) with Gore-Tex. There was no significant publication bias present in VHI outcomes. Silicone and Gore-Tex implants provide adequate and comparable results in TT1. The data supporting this conclusion are limited by follow-up, diversity in outcomes, limited data availability, and publication bias. Future research should be dedicated to comparing implants in a well-randomized environment. Laryngoscope, 2024.

Low Contact Strategy to Measure Flutamide’s Effects on Territorial Aggression in C57BL/6J Male Mice

While numerous factors contribute to mouse behavior, biological drivers are paramount to many regulatory processes that undergird behavior. In particular, the sex hormone testosterone plays a key role in the regulation of aggression, physical activity, mating, and other behaviors known to be influenced by the presence of an experimenter. Due to this experimenter bias, strategies that minimize direct and frequent contact with research animals are needed to reduce any undesirable effects. The purpose of this research was to explore the effects of an androgen receptor antagonist (Flutamide) on territorial aggression in male C57BL/6J mice utilizing a low contact technique for chemical delivery. It was hypothesized that the introduction of an androgen receptor inhibiting substance under a low contact delivery strategy would result in effective reduction of the territorial aggression response in mice introduced to an unknown male mouse in the home cage environment, mimicking similar blunting responses characterized in previous work evaluating aggression in rodents. Silastic (Dow Corning, Midland, MI) implants were used as the lower contact delivery strategy for drug administration. This strategy allowed minimal contact with the experimental technician and eliminated the need for daily contact required for the commonly used injection strategies employed elsewhere. A series of aggression trials before, 24, 96, and 192 hours after Flutamide implantation were conducted in three groups of mice. Control mice (n=4) received 100% Cholesterol-containing implants, low exposure mice (n=5) received 80% Cholesterol/20% Flutamide-containing implants, and high exposure mice (n=5) received 100% Flutamide-containing implants. Each aggression trial consisted of introducing a foreign mouse to an experimental mouse’s home cage for an 8-minute period. The time to initial aggression and the total number of aggressions over the 8 minutes was quantified. The time to initial aggression was unaffected by flutamide administration throughout the study [F(26,91) =0.37, p=0.864]. The total number of aggressions were significantly affected by flutamide exposure [F(28,82) = 2.90, p=0.029]. Follow-up post hoc testing indicated a significant reduction in aggression in both the low and high dose groups 24 (low: p = 0.001; high = 0.001) and 96 (low: p = 0.009; high = 0.012) hours after implantation compared to the control at the same time points. The use of Silastic implants to deliver the anti-androgenic compound was a valuable technique that reduced research animal contact with experimental technicians. This technique can be modified for prolonged exposure by lengthening the implant or increasing the diameter of the Silastic tubing. This anti-androgen exposure methodology requiring less interaction reduces the confounding variables that impact mouse behavior and could prove beneficial to observe and study other androgen-related behaviors including physical activity and mating. All funding for this research was provided by the Union University Department of Biology. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Acoustics and aerodynamic effects following glottal and infraglottal medialization in an excised larynx model

ObjectiveThis study aimed to investigate the impact of the implant’s vertical location during Type 1 Thyroplasty (T1T) on acoustics and glottal aerodynamics using excised canine larynx model, providing insights into the optimal technique for treating unilateral vocal fold paralysis (UVFP).MethodsMeasurements were conducted in six excised canine larynges using Silastic implants. Two implant locations, glottal and infraglottal, were tested for each larynx at low and high subglottal pressure levels. Acoustic and intraglottal flow velocity field measurements were taken to assess vocal efficiency (VE), cepstral peak prominence (CPP), and the development of intraglottal vortices.ResultsThe results indicated that the implant's vertical location significantly influenced vocal efficiency (p = 0.045), with the infraglottal implant generally yielding higher VE values. The effect on CPP was not statistically significant (p = 0.234). Intraglottal velocity field measurements demonstrated larger glottal divergence angles and stronger vortices with the infraglottal implant.ConclusionThe findings suggest that medializing the paralyzed fold at the infraglottal level rather than the glottal level can lead to improved vocal efficiency. The observed larger divergence angles and stronger intraglottal vortices with infraglottal medialization may enhance voice outcomes in UVFP patients. These findings have important implications for optimizing T1T procedures and improving voice quality in individuals with UVFP. Further research is warranted to validate these results in clinical settings.

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.

Fabrication of silastic testosterone enanthate implants to achieve virilizing levels of serum testosterone in swine

The aim of this study was to create a continuous drug delivery system that would yield serum testosterone levels in sexually mature, female pigs consistent with serum testosterone levels of human transgender men. Testosterone enanthate was mixed with medical grade silicone at a ratio of 20 % by weight, placed in silastic tubing to cure at room temperature for 24 h, then removed from the tubing mold and stored at 4 °C until surgical implantation. Testosterone enanthate oxidizes at high temperatures which is why the implants had to be stored cold. Each implant was 9 cm long and contained 0.56 g of testosterone enanthate. A minimum of one implant (0.56 g testosterone enanthate) and a maximum of four implants (2.24 g testosterone enanthate) were placed in the cervical subcutaneous fat of each pig. After implantation, serum testosterone was assessed over 40 days. Silastic testosterone enanthate implants increase serum testosterone and maintain it in a relatively constant state in a dose-dependent manner for ∼ 21–25 days post-implantation.•Effective method for subcutaneous delivery of large quantities of testosterone or testosterone metabolites in compact implants to large animal biomedical model species.•Maintains increased circulating testosterone levels for up to 3, 4 weeks post-implantation in pigs.

SAT415 Development Of A Novel, Preclinical Swine Model Of Transgender Men To Assess Testosterone Impact On Insulin Sensitivity And Whole-Body Metabolism

Abstract Disclosure: N. Mahabir: None. I. Ahmad: None. T. Wright: None. G. Ten Have: None. N. Deutz: None. A.E. Newell-Fugate: None. The effects oftestosterone therapy on peripheral insulin sensitivity in transgender men areequivocal due to heterogeneity of the population, short term patientfollow-up, and small cohort sizes. Most research has found testosterone therapyto decrease or have no effect on insulin sensitivity, but in one studytransgender men had increased insulin sensitivity. We have found thatshort-term, virilizing doses of testosterone in female pigs suppress circulatinginsulin levels. The objective of the current study was to develop a long-term,preclinical model of transgender men to assess insulin sensitivity and whole-bodymetabolism. A swine model of transgender men is superior to other models,because pigs closely mimic human cardiometabolic physiology and their largebody size permits longitudinal sampling and interventional procedures. Togenerate stable, long-term serum testosterone (TEST) concentrations in femalepigs, we fabricated testosterone silastic implants at the following doses:placebo (30 mm, n=1) or 15 mm (n=2), 30 mm (n=2), 60 mm (n=2), or 120 mm (n=1)TEST. Eight sexually mature female pigs were administered 14 days of progestin(Altrenogest) which was withdrawn on day 15. On day 16, 400 I.U. of pregnantmare serum gonadotropin and 200 I.U of human chorionic gonadotropin (PG600®,Merck Animal Health) were administered intramuscularly to stimulatefolliculogenesis and ovulation. Pigs had estrus detection performed dailythroughout the study and came into estrus 3-7 days post PG600® injection.Twenty-four hours post-estrus, implants were surgically placed subcutaneously,blood was taken, and biopsies of subcutaneous white adipose tissue werecollected from the incision site for baseline assessment of mitochondrialoxygen flux (Oroboros) and proteomic measurement of mitochondrial and insulinpathway abundance. After implant placement, fasted blood was collected at 24,48, 72 hours and every three days thereafter for six weeks. During weeks 2-6post-implantation, continuous glucose monitoring was performed (Freestyle Libre3). Twenty-four hours prior to study completion, a catheter was placed in thecranial vena cava and an intravenous glucose tolerance test was performed (0,5, 10, 20, 30, 40, 50, 60 min). The next morning fasted blood was collected (time0) and a stable isotopic tracer bolus was administered to measure whole bodyproduction of glycerol, branched chain amino acids, branched chain keto acids, and β-hydroxyβ-methylbutyric acid. After tracer bolus, blood was collected at 10, 20, 40, 60and 120 minutes. At 120 minutes post-bolus, tissues were collected for isotopiccompound measurement, mitochondrial function assays, and insulin signalingpathway assessment. This translational swine model will help uncover themechanistic effects of testosterone therapy on insulin sensitivity and whole-bodymetabolism in female to male transitioning patients. Presentation: Saturday, June 17, 2023

Cardiovascular Safety and Benefits of Testosterone Implant Therapy in Postmenopausal Women: Where Are We?

We discuss the CV safety and efficacy data for subcutaneous testosterone therapy (STT) in postmenopausal women. We also highlight new directions and applications of correct dosages performed in a specialized center. To recommend STT, we propose innovative criteria (IDEALSTT) according to total testosterone (T) level, carotid artery intima-media thickness, and calculated SCORE for a 10-year risk of fatal cardiovascular disease (CVD). Despite all the controversies, hormone replacement therapy (HRT) with T has gained prominence in treating pre and postmenopausal women in the last decades. HRT with silastic and bioabsorbable testosterone hormone implants has gained prominence recently due to its practicality and effectiveness in treating menopausal symptoms and hypoactive sexual desire disorder. A recent publication on the complications of STT, looking at a large cohort of patients over seven years, demonstrated its long-term safety. However, the cardiovascular (CV) risk and safety of STT in women are still controversial.

Correction of a Visible Silastic Implant Using the Dual-layered Capsular Flaps.

Alloplastic implants used for dorsal augmentations can induce surgical and cosmetic complications. One of these cosmetic complications is when the implant is visible through the skin. In these cases, it is recommended to use an autologous soft tissue to reinforce the area between the skin and the implant. Recently, a patient visited our institute complaining of a previously inserted silastic implant being visible through the skin. Based on the implant, we hypothesized that the surrounding soft tissue might have formed 2 capsular layers, and the implant might have separated from the capsular. During the revision rhinoplasty, we peeled off the 2 capsular layers and used them to reinforce the area between the implant and skin without harvesting autologous tissue. This procedure had a satisfactory surgical outcome and a shorter operative time than harvesting autologous tissue. Here, we describe our experience and share lessons from this case.

Hormonal and genotoxic estrogen-androgen carcinogenesis in the NBL rat prostate: A role for aromatase.

Androgens are generally thought to cause prostate cancer, but the data from animal studies suggest that they must be aromatized to estrogen and act in concert with genotoxic estrogen metabolites. The objective of this study was to determine whether treatment with testosterone (T) combined with a nonestrogenic estrogen metabolite and a nongenotoxic estrogenic compound would all be necessary and sufficient for the induction of a high incidence of prostate cancer in the susceptible NBL rat strain. NBL rats were treated with low-dose testosterone via slow-release Silastic implants and with the marginally estrogenic genotoxic catechol estrogen 4-hydroxyestradiol (4OH-E2) and the nongenotoxic estrogen 2-fluoroestradiol (2F-E2) and in one experiment the aromatase inhibitor letrozole via custom-made slow-release pellets. Animals were euthanized 52 weeks after implantation and their pituitaries and prostate complexes weighed and fixed in formalin. Hematoxylin and eosin (H&E)-stained step sections were prepared and examined microscopically for proliferative lesions. Animals treated with 2F-E2, with or without the other compounds, had enlarged pituitaries demonstrating its estrogenicity. Animals treated with T, with or without the other compounds, had enlarged prostates consistent with its androgenicity. Rats treated with T plus 2F-E2 and 4OH-E2 developed a high incidence of prostatic cancer (89%), while, surprisingly, rats treated with T plus only 2F-E2 also had a high incidence of prostate cancer (95%) contradicting our initial hypothesis. To test whether the formation of E2 from T by aromatase could lead to estrogen genotoxicity and prostate carcinogenesis we then rats treated with T and 2F-E2 also with letrozole and found that it reduced prostate cancer incidence by about 50%. These findings indicate that long-term treatment with a nongenotoxic estrogen (2F-E2) and T as well as uninhibited prostatic aromatase activity generating genotoxic E2 are all required for induction of a high incidence of prostatic adenocarcinomas in NBL rats. These and previous data indicate that androgen receptor-mediated action, estrogen receptor mediation, and estrogen genotoxicity are all required and sufficient for hormonal carcinogenesis in the NBL rat prostate. Interference with the estrogen genotoxicity is a potential approach to prostate cancer chemoprevention.

Removal of six levonorgestrel silastic subcutaneous implants twenty-five years after insertion

Removal of six levonorgestrel silastic subcutaneous implants twenty-five years after insertion

Effects of perinatal exposure to bisphenol A on induction of prostate cancer in Sprague Dawley rats by MNU and testosterone

Perinatal and neonatal exposure to bisphenol A (BPA) has been linked to enhancement of prostate carcinogenesis in rats induced by combined treatment with estradiol and testosterone, but human data are lacking. This study aimed to determine the effects of perinatal BPA exposure on induction of prostate cancer in rats by sequential treatment with N-methyl-N-nitrosamine (MNU) and continuous low dose administration of testosterone. Pregnant Sprague Dawley rats were exposed to BPA administered by subcutaneous Alzet minipumps at doses of 2.5 or 25 µg/kg body weight/day from gestational day 9 until postnatal day 28 when pups were weaned providing exposure of offspring in utero and via the mother’s milk. At 10–12 weeks of age, one male offspring per litter was treated with an intraperitoneal injection of MNU after hormonal stimulation of prostatic cell proliferation followed two weeks later by subcutaneous insertion of Silastic implants containing testosterone until the termination of the study 57–58 weeks after MNU injection. The perinatal BPA exposure did not significantly affect the incidence of prostate carcinomas which was slightly lower in exposed rats (33–23 %) than in control animals (40 %). Carcinomas in all accessory sex glands combined were also insignificantly less frequent in exposed (46–48 %) than in control rats (60 %). The incidence of malignant tumors at any site in the body was significantly lower in exposed rats (81–65 %) than in controls (93 %). In conclusion, perinatal BPA exposure did not significantly modify prostate cancer induction by MNU plus testosterone in rats, unlike the enhancement of prostate carcinogenesis induced by treatments involving estradiol administration. Which of the two models of prostate carcinogenesis is more relevant for the human situation is unclear at present.

Unexpected long-term retention of subcutaneous beeswax implants and additional notes on dose and composition from four testosterone implant studies

Experimental manipulations of testosterone have advanced our understanding of the hormonal control of traits across vertebrates. Implants are commonly used to supplement testosterone and other hormones to organisms, as they can be readily scaled to produce desired hormone levels in circulation. Concerns about pharmacological (i.e. unnatural) doses of traditional silastic implants led to innovation in implant methods, with time-release pellets and beeswax implants proposed as solutions. A study comparing silastic, time-release pellets, and beeswax implants found the latter to be most effective in delivering a physiologically relevant dose. One proposed advantage to subcutaneous beeswax implants is that they are expected to degrade within the body, thus removing the obligation to recapture implanted individuals in the field. However, few studies have reported on dosage and no published literature has examined the assumption that beeswax implants readily degrade as expected. Here we present time-release androgen data in relation to implants containing varying levels of testosterone from four separate implant studies. In addition, we report long-term persistence of subcutaneous implants, including two cases of implants being retained for > 2 years. Finally, we offer recommendations on the composition and implementation of beeswax implants to aid the pursuit of minimally invasive and physiologically relevant manipulations of circulating hormones.

Optimizing the Lip Aesthetic Ratio Using Surgically Placed Silastic Implants for Lip Augmentation

Introduction: Lip augmentation can be achieved using dermal fillers, biological tissues (fat, fascia, scar tissue, Alloderm), and a permanent soft silastic implant. Patients choosing the permanent lip implant were evaluated for aesthetic outcome, patient satisfaction, complications, and the use of dermal fillers postoperatively. Materials and Methods: Retrospective review of lip implant augmentation was performed in a single private practice. Analysis of aesthetic outcomes, adverse effects, methodology to determine optimal lip implant size, surgical technique caveats, and the use of dermal fillers before and after lip implant placement was carried out. Aesthetic outcomes and patient satisfaction were assessed by direct patient questioning and surgeon observation. Results: A total of 100 lip implant augmentation patients with 192 implants (92 combined upper and lower lips, 4 upper lip only, 4 lower lip only) were placed by the author between May 2011 and September 2021. From a patient satisfaction standpoint, 97% were happy with the final lip augmentation outcome. There was a complication incidence of 8%, with implant asymmetry the most common. Some patients (7%) underwent dermal fillers, both polymethylmethacrylate to the vermillion border and hyaluronic acid filler to the bulk of the lip to provide additional lip enhancement. Discussion: Silastic lip implant satisfies the following factors for lip augmentation: precise, accepted by the host, modifiable, natural feel, readily reversible, and permanency. The author’s quantitative method uses primarily the “golden ratio” (1:1.62) as the most impactful metric of size determination of the upper and lower lip followed by two-third incisor dental show. Most patients (94%) used lip dermal fillers prior to surgery to assess satisfaction with lip augmentation. Our results revealed larger lip implant size placement (4- and 5-mm diameter implants) compared with the largest study published. Lip bulk augmentation with hyaluronic acid fillers injected superficial to the implant capsule may be performed safely after permanent lip implant placement to achieve the patients’ desired outcome. It is best to be an advanced filler injector and to use a microcannula for filler placement. Conclusions: The soft silastic lip implant procedure is a simple surgical procedure with a high patient satisfaction rate and low complication rate. Knowledge of lip aesthetic mathematical ratios and degree of dental show is imperative. Additional lip enhancement to lip bulk and vermillion border using both temporary and permanent dermal fillers may be performed safely after permanent lip implant placement to achieve the patients’ desired outcome.

Pharmacokinetic comparison of three delivery systems for subcutaneous testosterone administration in female mice

Transmasculine individuals are often prescribed testosterone (T) for masculinizing hormone therapy. Mouse models mimicking transmasculine T therapy require reliable long-term T administration. The objectives of this study were three-fold, namely, to compare: 1) the release dynamics of three different subcutaneous delivery systems of T enanthate administration (subcutaneous injections, commercially available pellets, and silastic implants) over a 6-week period in postpubertal C57BL/6N mice, 2) to compare the timing for T levels in plasma to return to baseline and cyclicity to resume after cessation of T between injections and pellets, 3) to utilize silastic implants to achieve sustainable increase in T levels utilizing T enanthate and crystalline T. All three modes of T administration resulted in an increase in T levels in plasma. Pharmacokinetic analyses showed a similar overall exposure to T enanthate over 6 weeks (integrated area) for, subcutaneous injection (0.45 mg two times per week and 0.90 mg one time per week), pellet (5 mg 60-day release), and silastic implant (5 mg 21 week) groups. Crystalline T had lower solubility and a decreased integrated area compared to T enanthate, even when implanted at a higher dosage, indicating different pharmacokinetic profiles based on type of T formulation when utilizing the same silastic delivery method. Surgical removal of pellets and silastic tubing led to a quick drop in T levels and resumption of estrous cyclicity, while cessation of injections required a long washout period for T levels to drop and estrous cycles to resume. Sustained elevation in T levels was achieved for at least 21 weeks with silastic implants. As all three delivery methods are able to elevate T levels in female mice for at least 6 weeks, choice of T administration method should be based on outcomes of interest and study design.

Concepts in Hip Implant Body Contouring: Patient Evaluation & Implant Fabrication

Introduction: One of the most requested aesthetic procedures is body contouring using liposuction. Adjunctive procedures using fat grafting can provide enhancement in most body areas, commonly used in both gluteal and hip augmentation. Performing processing and enrichment to optimize fat transfer survival can avoid the use of body implants. When there is insufficient fat for the desired degree of augmentation, silastic implant placement is an alternative treatment. Much has been written in the medical cosmetic literature regarding gluteal and breast implants, but nothing in terms of hip silastic implants. Material and Methods: Hip implant patient selection, the body frame analysis, associated enhancing body contouring procedures, implant design and fabrication, and implant surgical placement are analyzed. In 3 different cosmetic surgery practices, methods of patient analysis and the process of creating a custom hip implant is presented. Techniques and protocols in the use of fat grafting in association with both gluteal and hip implants are elucidated. Results: The minimally manipulating fat maneuvers to increase fat survival are detailed. This paper defines the process of planning, designing, and fabricating a custom hip implant with significant patient input. By definition, patient-specific or custom implants can be any shape, size, and projection. The patient and surgeon provide the implant fabrication company a paper tracing of the surface area of the proposed implant along with the maximum projection. Engineering creates a 2-dimensional drawing using a computational software for intelligent system design or CAD. The implants are fabricated with input from the surgeon on silastic durometer, implant alterations to lower weight and enhance ease of folding for placement, and shape. Caveats and pitfalls in surgical planning, implant design, fabrication, and surgical placement are identified. Discussion: Body contouring using ultrasound liposuction may provide the desired aesthetic result. When augmentation is requested, fat transfer is the preferred initial procedure. If there is an insufficient volume of fat to augment both the buttocks and hip area, hip fat grafting is preferred to avoid a hip alloplastic implant. The reason for this treatment recommendation is to avoid the hip implant with a higher risk profile. Once the indication for the hip implant is confirmed, usually because of either inadequate presence of fat or a desired maximum hip projection that cannot be attained by fat grafting alone, the body shape analysis is finalized. Conclusion: Custom silastic hip implants are designed, fabricated, and surgically placed to provide the patient desired cosmetic hip augmentation.

Treatment with androgens plus estrogens cannot reverse sex differences in song and the song control nuclei in adult canaries

Adult treatments with testosterone (T) do not activate singing behavior nor promote growth of song control nuclei to the same extent in male and female canaries (Serinus canaria). Because T acts in part via aromatization into an estrogen and brain aromatase activity is lower in females than in males in many vertebrates, we hypothesized that this enzymatic difference might explain the sex differences seen even after exposure to the same amount of T. Three groups of castrated males and 3 groups of photoregressed females (i.e., with quiescent ovaries following exposure to short days) received either 2 empty 10 mm silastic implants, one empty implant and one implant filled with T or one implant filled with T plus one with estradiol (E2). Songs were recorded for 3 h each week for 6 weeks before brains were collected and song control nuclei volumes were measured in Nissl-stained sections. Multiple measures of song were still different in males and females following treatment with T. Co-administration of E2 did not improve these measures and even tended to inhibit some measures such as song rate and song duration. The volume of forebrain song control nuclei (HVC, RA, Area X) and the rate of neurogenesis in HVC was increased by the two steroid treatments, but remained significantly smaller in females than in males irrespective of the endocrine condition. These sex differences are thus not caused by a lower aromatization of the steroid; sex differences in canaries are probably organized either by early steroid action or by sex-specific gene regulation directly in the brain.

Sodium arsenite does not affect prostate carcinogenesis in a chemically-hormonally-induced rat model

There is epidemiologic evidence to suggest that arsenic exposure is associated with risk of prostate cancer incidence and mortality. There are no studies indicating that arsenic can induce prostate cancer in animals. We evaluated whether drinking water exposure to sodium arsenite would affect prostate carcinogenesis in a rat model that depends on long-term low dose treatment with testosterone. WU rats received a sequential treatment with the antiandrogen flutamide followed by a single androgen administration to stimulate prostatic cell proliferation during which a single injection of N-methyl-N-nitrosourea was given. Two weeks later the animals received subcutaneous slow release testosterone-containing silastic tubing implants and provided with drinking water containing 5 mg/L sodium arsenite or with control drinking water for the duration of the 64 week-long experiment. Arsenite provided in drinking water did not modify the induction of prostate cancer in this rat model compared to control rats or survival. It also did not affect the growth of the animals or their drinking water intake. This animal study with drinking water exposure to 5 mg/L sodium arsenite does not support the notion that arsenic enhances prostate carcinogenesis.

Post‐Pubertal Testosterone Implants Induce Hypertension in Female‐to‐Male Trans‐Sex Rat Model

IntroductionAndrogens induce increases in blood pressure (BP) and risk of cardiovascular diseases (CVDs) in females, as seen in polycystic ovary syndrome females. However, it is not clear whether treatment with gender‐affirming hormone therapy in trans‐men have an impact on their BP or risk of CVD. Therefore, the present study was undertaken to test the hypothesis that chronic androgen supplements (starting post pubertal) in a rodent model of transgender men, will increase BP and promote metabolic dysfunction.MethodsFemale SD rats were implanted with testosterone propionate (TP, 7.5 mg in 5 mm silastic tubes, replaced every 3 wks, n = 10) starting at 7 wks of age (post‐puberty) and compared to controls (empty silastic implants, n = 10). Rats were weighed weekly. Radiotelemetry transmitters were implanted at 13 wks of age (n = 5‐6/group) and mean arterial pressure (MAP) was measured at 15, 21 and 25 wks of age. Body composition was determined at 15, 21 and 23 wks of age and proteinuria was determined at 15 and 21 wks of age (n = 4/group). Serum testosterone was measured by LC/MS at 15 wks of age (n = 4/group). Oral glucose tolerance test was performed at 11 and 22 wks of age (n = 4/group).ResultsTP supplements increased serum testosterone at 15 wks of age by 30‐fold compared to female controls (6.4 ± 1.5 vs 0.2 ± 0.05 ng/ml, respectively; p<0.005). Body weight (BW) increased significantly in TP group compared to controls by 10 wks of age (241 ± 4 g vs 220 ± 2 g, respectively; p<0.05) and was sustained through 26 wks of age (311 ± 7 g vs 276 ± 5 g, respectively; p<0.05). Fat mass and fat mass/BW were similar between TP and controls. Lean mass was significantly higher in TP group compared to controls at 15, 21 and 23 wks of age (254 ± 7, 268 ± 12 and 273 ± 12 g vs 218 ± 6, 227 ± 5 and 229 ± 5 g, respectively; p<0.01); however, when factored for BW, there were no differences between TP and controls. Proteinuria was significantly higher in TP group compared to controls at 15 wks of age (4.9 ± 1.2 vs 2.1 ± 0.3 mg/24 h, respectively, p<0.05) and 21 wks of age (7.6 ± 1.1 vs 2.4 ± 0.5 mg/24 h, respectively, p<0.005). Importantly, MAP was increased significantly in TP group at 15 wks of age (112 ± 3 vs 106 ± 4 mmHg, p<0.05), 21 wks of age (114 ± 3 vs 105 ± 2 mmHg; p<0.05) and 24 wks of age (115 ± 3 vs 104 ± 2 mmHg, p<0.05), compared to controls, respectively. Oral glucose tolerance test at 11 and 22 wks of age was similar between groups.ConclusionTestosterone used in a form of sex‐affirming therapy in female rats induced increases in BP that are independent of adiposity or Insulin resistance and maybe associated to renal injury. Future studies should determine whether these changes are sustained with aging, and the mechanisms responsible for the increase in BP in the female‐to‐male trans‐sex model.

Evolving Clinical Experiences in Aesthetic Hip Implant Body Contouring.

Hip augmentation increases the hip width utilizing fat transfer and/or subcutaneous implants, creating a more feminine hourglass shape. Custom hip implant surgery requires proper patient selection, correct body frame analysis, appreciation of hip aesthetics, understanding surgical anatomy, optimal aesthetic planning, a favorable implant design and fabrication, skilled surgical implant placement, diligent postoperative patient care, and proper complication management. The authors sought to evaluate the pioneering clinical experience with cosmetic custom hip silastic implants. A consecutive patient surgical series of patients seeking custom aesthetic hip implant surgery was tabulated. Similar hip analysis, implant design and fabrication, surgical technique, and postoperative follow-up were performed in 3 practices. The overall patient satisfaction rate (87%, 47 of 54 patients) was favorable. There was a total of 29 (54%) medical complications and 20 (37%) cosmetic complications (implant show). A total of 17 patients (31.5%) requested revision surgery secondary to implant show (n = 10) and an infected implant (n = 6). No patient experienced an acute implant infection, incisional scar hypertrophy, wound dehiscence, implant extrusion, parasthesias, muscle dysfunction, or hip joint injury. The utilization of hip implants represents a new type of body contouring implant that has some unique differences in anatomic location, implant design, and tissue pocket location. Their utilization is an evolving one in aesthetic body implants, for which clinical experience to date remains limited in number. The proper surgical placement, postoperative management, and treatment of complications to include revision surgery are essential to achieving a successful body contouring outcome.

Heterothermy as a mechanism to offset energetic costs of environmental and homeostatic perturbations

Environmental and biotic pressures impose homeostatic costs on all organisms. The energetic costs of maintaining high body temperatures (Tb) render endotherms sensitive to pressures that increase foraging costs. In response, some mammals become more heterothermic to conserve energy. We measured Tb in banner-tailed kangaroo rats (Dipodomys spectabilis) to test and disentangle the effects of air temperature and moonlight (a proxy for predation risk) on thermoregulatory homeostasis. We further perturbed homeostasis in some animals with chronic corticosterone (CORT) via silastic implants. Heterothermy increased across summer, consistent with the predicted effect of lunar illumination (and predation), and in the direction opposite to the predicted effect of environmental temperatures. The effect of lunar illumination was also evident within nights as animals maintained low Tb when the moon was above the horizon. The pattern was accentuated in CORT-treated animals, suggesting they adopted an even further heightened risk-avoidance strategy that might impose reduced foraging and energy intake. Still, CORT-treatment did not affect body condition over the entire study, indicating kangaroo rats offset decreases in energy intake through energy savings associated with heterothermy. Environmental conditions receive the most attention in studies of thermoregulatory homeostasis, but we demonstrated here that biotic factors can be more important and should be considered in future studies.