Investigating child sexual abuse material availability, searches, and users on the anonymous Tor network for a public health intervention strategy

Tor is widely used for staying anonymous online and accessing onion websites; unfortunately, Tor is popular for distributing and viewing illicit child sexual abuse material (CSAM). From 2018 to 2023, we analyse 176,683 onion domains and find that one-fifth share CSAM. We find that CSAM is easily available using 21 out of the 26 most-used Tor search engines. We analyse 110,133,715 search sessions from the Ahmia.fi search engine and discover that 11.1% seek CSAM. When searching CSAM by age, 40.5% search for 11-year-olds and younger; 11.0% for 12-year-olds; 8.2% for 13-year-olds; 11.6% for 14-year-olds; 10.9% for 15-year-olds; and 12.7% for 16-year-olds. We demonstrate accurate filtering for search engines, introduce intervention, show a questionnaire for CSAM users, and analyse 11,470 responses. 65.3% of CSAM users first saw the material when they were children themselves, and half of the respondents first saw the material accidentally, demonstrating the availability of CSAM. 48.1% want to stop using CSAM. Some seek help through Tor, and self-help websites are popular. Our survey finds commonalities between CSAM use and addiction. Help-seeking correlates with increasing viewing duration and frequency, depression, anxiety, self-harming thoughts, guilt, and shame. Yet, 73.9% of help seekers have not been able to receive it.

Differentiation of placental trophoblast giant cells requires downregulation of p53 and Rb

Trophoblast giant cells in the rodent placenta form the outermost layer of the extraembryonic compartment, establish direct contact with maternal cells, and produce a number of pregnancy-specific cytokine hormones. Giant cells differentiate from proliferative trophoblasts as they exit the cell cycle and enter a genome-amplifying endocycle, a process we show involves decreased expression of the G1 checkpoint proteins p53 and Rb. Although p53 mRNA levels are unchanged in proliferative compared to differentiated trophoblasts, p53 protein levels are markedly reduced in giant cells. Forced expression of wild type p53 in trophoblasts inhibits differentiation, and expression of a dominant negative p53 peptide stimulates differentiation. Consistent with the loss of p53 protein, differentiated trophoblasts become resistant to apoptosis-inducing agents. Decreased expression of Rb is also detected during differentiation, and overexpression of Rb in trophoblasts inhibits giant cell differentiation. Although an increase in E2F activity would be expected with the loss of Rb, what is observed is an overall decrease in E2F DNA-binding complexes, a shift to new complexes, and a decrease in E2F-dependent gene expression in differentiating trophoblasts. Overall, these results indicate that the combination of a decrease in p53 and Rb represents a functionally important part of the transition of trophoblasts from a proliferative cell cycle to an endocycle in the giant cell differentiation programme.

Nodal regulates trophoblast differentiation and placental development

Nodal has been thought to be an embryo-specific factor that regulates development, but nodal is also expressed in the mouse placenta beginning at midgestation, specifically in the spongiotrophoblasts. In an insertional null nodal mutant, not only is embryonic development disrupted, but mouse placental development is also grossly altered with the loss of the diploid spongiotrophoblasts and labyrinth and an expansion of the polyploid giant cell layer. A hypomorphic mutation in nodal results in an expansion of the giant cell and spongiotrophoblast layers, and a decrease in labyrinthine development. Expression of nodal in trophoblast cell cultures is sufficient to inhibit trophoblast giant cell differentiation, demonstrating that nodal can act directly on trophoblasts. The mechanism of nodal action includes the inhibition of junB gene transcription. These results suggest that nodal may be involved in redirecting trophoblast fate towards the midgestational expansion of the labyrinth region while maintaining the thin layer of trophoblast giant cells and the underlying layer of spongiotrophoblasts that form the boundary between the maternal and extraembryonic compartments.

Expression of human alpha 2-adrenergic receptors in adipose tissue of beta 3-adrenergic receptor-deficient mice promotes diet-induced obesity

Catecholamines play an important role in controlling white adipose tissue function and development. beta- and alpha 2-adrenergic receptors (ARs) couple positively and negatively, respectively, to adenylyl cyclase and are co-expressed in human adipocytes. Previous studies have demonstrated increased adipocyte alpha 2/beta-AR balance in obesity, and it has been proposed that increased alpha 2-ARs in adipose tissue with or without decreased beta-ARs may contribute mechanistically to the development of increased fat mass. To critically test this hypothesis, adipocyte alpha 2/beta-AR balance was genetically manipulated in mice. Human alpha 2A-ARs were transgenically expressed in the adipose tissue of mice that were either homozygous (-/-) or heterozygous (+/-) for a disrupted beta 3-AR allele. Mice expressing alpha 2-ARs in fat, in the absence of beta 3-ARs (beta 3-AR -/- background), developed high fat diet-induced obesity. Strikingly, this effect was due entirely to adipocyte hyperplasia and required the presence of alpha2-ARs, the absence of beta 3-ARs, and a high fat diet. Of note, obese alpha 2-transgenic beta 3 -/- mice failed to develop insulin resistance, which may reflect the fact that expanded fat mass was due to adipocyte hyperplasia and not adipocyte hypertrophy. In summary, we have demonstrated that increased alpha 2/beta-AR balance in adipocytes promotes obesity by stimulating adipocyte hyperplasia. This study also demonstrates one way in which two genes (alpha 2 and beta 3-AR) and diet interact to influence fat mass.

Transgenic mice overexpressing the beta 1-adrenergic receptor in adipose tissue are resistant to obesity

The ratio of alpha- to beta-receptors is thought to regulate the lipolytic index of adipose depots. To determine whether increasing the activity of the beta 1-adrenergic receptor (AR) in adipose tissue would affect the lipolytic rate or the development of this tissue, we used the enhancer-promoter region of the adipocyte lipid-binding protein (aP2) gene to direct expression of the human beta 1 AR cDNA to adipose tissue. Expression of the transgene was seen only in brown and white adipose tissue. Adipocytes from transgenic mice were more responsive to beta AR agonists than were adipocytes from nontransgenic mice, both in terms of cAMP production and lipolytic rates. Transgenic animals were partially resistant to diet-induced obesity. They had smaller adipose tissue depots than their nontransgenic littermates, reflecting decreased lipid accumulation in their adipocytes. In addition to increasing the lipolytic rate, overexpression of the beta 1 AR induced the abundant appearance of brown fat cells in subcutaneous white adipose tissue. These results demonstrate that the beta 1 AR is involved in both stimulation of lipolysis and the proliferation of brown fat cells in the context of the whole organism. Moreover, it appears that it is the overall beta AR activity, rather than the particular subtype, that controls these phenomena.