More than 80 loss-of-function (LOF) mutations in the SLC6A8 creatine transporter (hCRT1) are responsible for cerebral creatine deficiency syndrome (CCDS), which gives rise to a spectrum of neurological defects, including intellectual disability, epilepsy, and autism spectrum disorder. To gain insight into the nature of the molecular defects caused by these mutations, we quantitatively profiled the cellular processing, trafficking, expression, and function of eight pathogenic CCDS variants in relation to the wild type (WT) and one neutral isoform. All eight CCDS variants exhibit measurable proteostatic deficiencies that likely contribute to the observed LOF. However, the magnitudes of their specific effects on the expression and trafficking of hCRT1 vary considerably, and we find that the LOF associated with two of these variants primarily arises from the disruption of the substrate-binding pocket. In conjunction with an analysis of structural models of the transporter, we use these data to suggest mechanistic classifications for these variants. To evaluate potential avenues for therapeutic intervention, we assessed the sensitivity of these variants to temperature and measured their response to the proteostasis regulator 4-phenylbutyrate (4-PBA). Only one of the tested variants (G132V) is sensitive to temperature, though its response to 4-PBA is negligible. Nevertheless, 4-PBA significantly enhances the activity of WT hCRT1 in HEK293T cells, which suggests it may be worth evaluating as a therapeutic for female intellectual disability patients carrying a single CCDS mutation. Together, these findings reveal that pathogenic SLC6A8 mutations cause a spectrum of molecular defects that should be taken into consideration in future efforts to develop CCDS therapeutics.

DNA levels were measured in the spinal cords of Lewis rats during the development of and recovery from experimental allergic encephalomyelitis (EAE). Spinal cord DNA was first increased 11 days after immunizing the rats with guinea pig myelin and rose to levels four times that of the Freund's adjuvant controls at day 14, then subsided after day 22. Spinal cord DNA was still 150% of control levels 60 days after immunization. These DNA changes were compared with fluctuations in spinal cord acid proteinase in the same animals. Acid proteinase activity in EAE spinal cord increased later than the rise in DNA and attained a level of 170% of control at days 15-17, then subsided. Spinal cord DNA was higher in rats immunized with whole myelin than in those administered equivalent amounts of purified myelin basic protein. Furthermore DNA was higher in spinal cords of rats immunized with a larger dose of myelin (1.0 mg) than with a lower amount (0.5 mg). Various protease inhibitors including pepstatin, nitrophenyl p-guanidino benzoate, polylysine, and dipropionyl rhein, previously shown to protect Lewis rats against EAE, suppressed the increase of DNA in the spinal cord. Measurement of DNA increases in the spinal cord of EAE animals provides a convenient reproducible measurement of the severity of inflammation in the CNS and provides an objective criterion for assessment of the efficacy of various agents screened as possible therapeutic treatment for multiple sclerosis.

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Background and Hypothesis: Cementless femoral fixation in total hip arthroplasty (THA) has increased in prevalence worldwide. However, cementless fixation in elderly patients is controversial due to the risk of periprosthetic fracture and/or femoral component loosening. We evaluated the effect of age on implant survivorship in patients ≥75 versus <75 years of age. Intraoperative fracture, mortality, and revision cause also were evaluated.     Project Methods: 532 cementless THAs performed with consistent surgical, perioperative, and rehabilitation protocols by one surgeon between 2011 and 2018 were retrospectively reviewed. Patients with less than two years follow-up were excluded. 84 patients were ≥75 and 448 were <75 years of age. Average follow-up was 44±12 months (p=0.965). Revision rate, intraoperative fracture, 90-day mortality, and overall mortality were compared with p<0.05 considered statistically significant.     Results: In the ≥75 group there were more females (70.2% vs. 59.2%, p=0.067), more ASA-PS class 3-4 (76.2% vs. 46.2%, p<0.001), and lower BMI (28.6±5.7 vs. 31.3±6.9, p<0.001). Patients <75 had more hip dysplasia (p=0.023) and patients ≥75 had more kidney disease (p<0.001). Revision rates between the ≥75 and <75 groups (1.2%, 1.8%) were not different (p=1.000). Moreover, there was no difference in femoral component revision (<75 = 62.5%, ≥75 = 0.0%, p=0.444) with all femoral revisions due to infection not fracture or loosening. Intraoperative fracture (<75 = 0.9%, ≥75 = 1.2%, p=0.578), 90-day-mortality (one in the younger group, none in the older group, p=1.000), overall mortality (10 in the younger, 4 in the older group, p=0.253), and mean months between surgery and death (p=0.694) did not differ in younger and older patients.     Conclusion and Potential Impact: Older patients had comparable implant survivorship compared to younger patients using cementless femoral fixation. In addition, there were no differences in risk for mortality or intraoperative fracture. These findings provide evidence for the safety and durability of cementless THA in elderly patients ≥75 years of age.