Estrogen oversees the maintenance of the female genetic program in terminally differentiated gonochorists

The sexual plasticity of the gonads is not retained after the completion of sex differentiation in vertebrates, except in some hermaphroditic species. Here, we report that the depletion of estradiol-17β (E2) by aromatase inhibitors (AI) for up to six months resulted in a functional female-to-male sex reversal in sexually-mature adults of two gonochoristic fish species, Nile tilapia and medaka. The sex-reversed fish showed a typical male pattern of E2 and androgen levels, secondary sexual characteristics, and male-like sex behavior, producing fertile sperm. Conversely, co-treatment of E2 inhibited AI-induced sex reversal. In situ hybridization of medaka gonads during AI-induced sex reversal indicated that cysts on the dorsal side of the adult ovaries are the origin of germ cells and Sertoli cells in the newly formed testicular tissue. Gonochoristic fish maintain their sexual plasticity until adulthood and E2 plays a critical role in maintaining the female phenotype.

CCN3 protein participates in bone regeneration as an inhibitory factor

CCN3, a member of the CCN protein family, inhibits osteoblast differentiation in vitro. However, the role of CCN3 in bone regeneration has not been well elucidated. In this study, we investigated the role of CCN3 in bone regeneration. We identified the Ccn3 gene by microarray analysis as a highly expressed gene at the early phase of bone regeneration in a mouse bone regeneration model. We confirmed the up-regulation of Ccn3 at the early phase of bone regeneration by RT-PCR, Western blot, and immunofluorescence analyses. Ccn3 transgenic mice, in which Ccn3 expression was driven by 2.3-kb Col1a1 promoter, showed osteopenia compared with wild-type mice, but Ccn3 knock-out mice showed no skeletal changes compared with wild-type mice. We analyzed the bone regeneration process in Ccn3 transgenic mice and Ccn3 knock-out mice by microcomputed tomography and histological analyses. Bone regeneration in Ccn3 knock-out mice was accelerated compared with that in wild-type mice. The mRNA expression levels of osteoblast-related genes (Runx2, Sp7, Col1a1, Alpl, and Bglap) in Ccn3 knock-out mice were up-regulated earlier than those in wild-type mice, as demonstrated by RT-PCR. Bone regeneration in Ccn3 transgenic mice showed no significant changes compared with that in wild-type mice. Phosphorylation of Smad1/5 was highly up-regulated at bone regeneration sites in Ccn3 KO mice compared with wild-type mice. These results indicate that CCN3 is up-regulated in the early phase of bone regeneration and acts as a negative regulator for bone regeneration. This study may contribute to the development of new strategies for bone regeneration therapy.

Age and gender patterns of thyroid cancer incidence in Ukraine depending on thyroid radiation doses from radioactive iodine exposure after the Chornobyl NPP accident

The objective of this study was to investigate the thyroid cancer incidence in a whole territory of Ukraine and to clear up its age and gender patterns depending on average regional (oblast) thyroid doses from radioactive iodine due to the Chornobyl accident. MATERIALS AND METHODS. On the basis of average accumulated thyroid doses from radioactive iodine the geographical regions of Ukraine with low and high average thyroid doses were identified for a comparative analysis performance. Methods of descriptive epidemiology were used.

RESULTS

The level and dynamics of thyroid cancer incidence were analyzed in different gender and age groups (both for attained age and age at the moment of the Chornobyl accident). Results of this study confirmed the radiation excess of thyroid cancer in individuals who were children and adolescents in 1986. Some excess was observed in elder age groups too. Especial situation was observed in female age group 40-49 at the moment of the Chornobyl accident i.e. the age-specific thyroid cancer incidence rates were significantly higher in "high exposure" regions comparing with "low exposure" ones during all years of observation within 1989-2009.

CONCLUSIONS

A probable radiation excess of thyroid cancer was suggested not only in children and adolescents but also in adult age groups. In elder age groups this excess was less expressed and manifested after a longer period of time. The origin of the phenomenon in female age group of 40-49 is unclear now. Hypothesis of combined effect of radiation and natural changing of hormonal status in this age should be checked in the future studies.

Stimulation of Osteogenesis in Bone Defects Implanted with Biodegradable Hydroxyapatite Composed of Rod-Shaped Particles under Mechanical Unloading

The aim of this study was to evaluate the influence of mechanical unloading on the repair of bone defects with implantation of biodegradable bone substitutes. Spherical granules of biodegradable hydroxyapatite composed of rod-shaped particles (RHA) or beta-tricalcium phosphate composed of rod-shaped particles (RTCP) were implanted into a bone defect created in the distal end of the right femur of 8-week-old Wistar rats. Two, 6, 10, and 22 weeks after implantation, part of the sciatic nerve in the thigh was resected and exposed to mechanical unloading for 2 weeks. Then, 4, 8, 12 and 24 weeks after implantation, repair of the bone defect was analyzed. As a control, the bone defect without implantation of ceramic granules was also analyzed. Both RHA and RTCP tended to be reduced, but the reduction was not obvious during the experimental period. At 12 and 24 weeks after implantation, the amount of newly formed bone in the animal implanted with RHA was significantly greater than that at 4 weeks after implantation, but that in the animal implanted with RTCP or without implantation was not significantly different. The number of osteoclasts in the region implanted with RHA was significantly larger than that of the region implanted with RTCP or without implantation at 12 and 24 weeks. The activities of alkaline phosphatase in osteoblasts and tartrate-resistant acid phosphatase in osteoclasts were remarkably increased in the bone defects with implantation compared with those in the bone defects without implantation. These results suggested that RHA stimulated osteogenesis and osteoclastogenesis even after 2 weeks of mechanical unloading, and that RHA could be expected to improve the repair of bone defects in patients under the condition of skeletal unloading.

Development of prostate cancer in a patient with primary hypogonadism: intratumoural steroidogenesis in prostate cancer tissues

Intratumoural steroidogenesis may play a significant role in the progression of prostate cancer (PC) in the context of long-term ablation of circulating testosterone (T). To clarify the mechanism accounting for the progression of PC in a 74-year-old man who had undergone bilateral orchiectomy when he was 5 years old, we performed immunohistochemical studies of androgen receptor (AR) and steroidogenic enzymes in the prostate. We also measured steroid hormone levels in the serum and prostate, as well as mRNA levels of genes mediating androgen metabolism in the prostate. Positive nuclear staining of AR was detected in malignant epithelial cells. The levels of androstenedione (Adione), T, and 5-alpha dihydrotestosterone (DHT) in the serum of the patient were similar to those in PC patients receiving neoadjuvant androgen deprivation therapy (ADT), but were higher in the patient's prostate than in PC patients not receiving ADT. The gene expression of CYP17A1 and HSD3B1 was not detected, whereas that of STS, HSD3B2, AKR1C3, SRD5A1, and SRD5A2 was detected. Moreover, cytoplasmic staining of HSD3B2, AKR1C3, SRD5A1, and SRD5A2 was detected in malignant epithelial cells. Hence, in the present case (a man with primary hypogonadism), steroidogenesis in PC tissues from adrenal androgens, especially dehydroepiandrosterone sulphate, was the mechanism accounting for progression of PC. This mechanism might help elucidate the development of castration-resistant PC.

Accelerated bone formation on photo-induced hydrophilic titanium implants: an experimental study in the dog mandible

OBJECTIVES

The purpose of this study was to investigate the effect of photo-induced hydrophilic titanium dioxide (TiO₂) on serum fibronectin (sFN) attachment, and further to evaluate initial osseointegration responses in the dog mandibles.

MATERIALS AND METHODS

To apply the anatase TiO₂ film, plasma source ion implantation (PSII) method followed by annealing was employed for the titanium disks and implants, which were then illuminated with UV-A for 24 h for the experimental groups. Non-deposited titanium disks and implants were prepared for the control group. Surface characterization was performed using the interferometer and contact angle analyzer. The attachments of sFN were evaluated using fluorescence emission analysis. Thereafter both groups of implants were placed in the mandible of six beagle dogs. Bone response was investigated with histological and histomorphometrical analyses after periods of 2 and 4 weeks.

RESULTS

The experimental groups exhibited strong hydrophilicity under UV-A illumination and showed significant improvement in sFN attachment. And further, the experimental implants enhanced the bone formation with the bone-to-implant contact of 42.7% after 2 weeks of healing (control: 28.4%).

CONCLUSIONS

The combined applications of plasma fibronectin and PSII to produce hydrophilic titanium surfaces could accelerate early osseointegration.

Near-field optical mapping of quantum Hall edge states

We report on the mapping of quantum-Hall edge states by quasiresonant photovoltage measurements using a near-field scanning optical microscope. We have observed fine structures near sample edges that shift inward with an increase in magnetic field in accordance with the shift of the positions of the quantum-Hall edge states. We have found a transition from the weak disorder regime where compressible-incompressble strips are visible to the strong disorder regime where fluctuations smear out incompressible strips.