Spermatogenesis rescue in a mouse deficient for the ubiquitin ligase SCF{beta}-TrCP by single substrate depletion.

beta-TrCP, the substrate recognition subunit of a Skp1-Cul1-F-box (SCF) ubiquitin ligase, is ubiquitously expressed from two distinct paralogs, targeting many regulatory proteins for proteasomal degradation. We generated inducible beta-TrCP hypomorphic mice and found that they are surprisingly healthy, yet have a severe testicular defect. We show that the two beta-TrCP paralogs have a nonredundant role in spermatogenesis. The testicular defect is tightly associated with cell adhesion failure within the seminiferous tubules and is fully reversible upon beta-TrCP restoration. Remarkably, testicular depletion of a single beta-TrCP substrate, Snail1, rescued the adhesion defect and restored spermatogenesis. Our studies highlight an unexpected functional reserve of this central E3, as well as a bottleneck in a specific tissue: a single substrate whose stabilization is incompatible with testicular differentiation.

Thymus Activity, Vitamin D, and Respiratory Infections in Adolescent Swimmers.

BACKGROUND: Several studies have identified associations between low vitamin D concentrations and risk of upper respiratory infections (URI). T lymphocytes have a major anti-viral role, are affected by vitamin D metabolism, and may mediate the link between vitamin D and URIs. Competitive swimmers have a relatively high rate of URIs, alongside a high prevalence of low vitamin D concentration. OBJECTIVES: To examine the associations linking T cell receptor excision circles (TREC, markers of thymus activity), circulating 25(OH)D concentrations and the effect of vitamin D supplementation, and URI symptoms in young competitive swimmers. METHODS: We tested 82 adolescent swimmers for serum 25(OH)D and TREC concentrations and found that 55 had vitamin D insufficiency. Randomized supplementation of either vitamin D3 or placebo was given for 12 winter weeks. URI symptoms were recorded weekly. The associations between TREC copy numbers, vitamin D and URI burden were examined. RESULTS: TREC concentrations decreased with the participants' age (r = -0.346, P = 0.003), with no significant between-gender difference. TREC concentrations did not materially differ among subjects with normal, insufficient or deficient vitamin D status, and were not affected by vitamin D supplementation. No significant correlations were found between TREC levels or their changes during the study period, and mean URI severity or duration. CONCLUSIONS: Thymus activity, represented by higher TREC levels, was not related to vitamin D concentrations or status, and was not affected by vitamin D supplementation in adolescent swimmers. TREC concentrations were not associated with URI severity or duration in this population.

Palliative Care in Early Dementia.

BACKGROUND: Palliative care is recommended for all people with dementia from diagnosis through end-of-life. However, palliative care needs and effective elements of palliative care are not well-defined for the earlier stages of dementia. OBJECTIVE: To systematically map current research on palliative care early in the disease trajectory of dementia. DESIGN: Scoping review of scientific literature. DATA SOURCES: PubMed, CINAHL, EMBASE, Cochrane, PsycINFO, Web of Science. REVIEW METHODS: We included studies published in English over the last decade (through March 2022) that focused on palliative care in early stages of dementia and targeted outcomes in palliative care domains. Two authors independently screened abstracts and full texts and scored the quality of included studies using tools by the Joanna Briggs Institute. RESULTS: Among the 77 papers reviewed, few addressed early stages of dementia specifically. We found that: 1) While "early" palliative care was not well-defined in the literature, evidence indicated that palliative care needs were present at or before diagnosis and across the trajectory. Notable opportunities for palliative care arise at 'tipping points' (i.e., when symptoms, functional status, or caregiving needs change). 2) Palliative care needs in early dementia include advocacy for goal-aligned care in the future, reassurance against the threat of negligence and abandonment by caregivers, planning for future scenarios of care (practical, individual, and relational needs), and establishing of long-term relationships with providers entrusted for care later in disease. 3) Elements of effective palliative care in early dementia could include dementia-specific ACP and goals of care discussions, navigation for building a network of support, provision of tools and resources for family, tailored care and knowledge of the person, and well-prepared dementia-care providers. The scarcity of palliative care studies aimed at early disease indicates a gap in the evidence in dementia care. CONCLUSION: The literature on palliative care in early dementia is sparse. Future studies should focus on assessment tools for optimizing timing of palliative care in early dementia, gaining better understanding of patient and family needs during early phases of disease, and providing training for providers and families in long-term relationships and communication around goals of care and future planning.

The Association Between Race and Place of Death Among Persons With Dementia.

CONTEXT: Little is known about racial differences in place of death for persons with dementia (PWD), who may be especially vulnerable to receiving care at end of life that is not concordant with their goals or that places higher burden on caregivers. OBJECTIVES: To determine if there are racial and ethnic differences in place of death among PWD. METHODS: We analyzed data from the nationally representative National Health and Aging Trends study. Participants were included if they had probable dementia as defined by a previously validated algorithm and died between 2012 and 2020. Race and ethnicity were self-reported. Place of death was obtained from post-mortem interviews with bereaved caregivers. RESULTS: The sample included 993 decedents with dementia (81.4% white; 11.0% black, 7.6% hispanic). A higher percentage of black and hispanic decedents died in the hospital (30.3% and 32.8%, respectively) compared to white decedents (19.0%). A higher percentage of white decedents died in the nursing home (31.0%) than black (22.4%) or hispanic decedents (15.0%) In adjusted analyses, black decedents had a higher odds of hospital death (AOR 1.50; 95% CI 1.01, 2.24) compared to white decedents, with similar trends found for hispanic decedents. CONCLUSION: We found racial and ethnic differences in location of death for PWD, with black and hispanic PWD more likely to die in the hospital compared to white PWD. More research is needed to determine if the differences found represent goal concordant care or rather lack of access to high quality of care at the end of life.