Thymus alteration in hepatic regeneration

Regional brain volume predicts response to methylphenidate treatment in individuals with ADHD

BACKGROUND

Despite the effectiveness of methylphenidate for treating ADHD, up to 30% of individuals with ADHD show poor responses to methylphenidate. Neuroimaging biomarkers to predict medication responses remain elusive. This study characterized neuroanatomical features that differentiated between clinically good and poor methylphenidate responders with ADHD.

METHODS

Using a naturalistic observation design selected from a larger cohort, we included 79 drug-naive individuals (aged 6-42 years) with ADHD without major psychiatric comorbidity, who had acceptable baseline structural MRI data quality. Based on a retrospective chart review, we defined responders by individuals' responses to at least one-month treatment with methylphenidate. A nonparametric mass-univariate voxel-based morphometric analysis was used to compare regional gray matter volume differences between good and poor responders. A multivariate pattern recognition based on the support vector machine was further implemented to identify neuroanatomical indicators to predict an individual's response.

RESULTS

63 and 16 individuals were classified in the good and poor responder group, respectively. Using the small-volume correction procedure based on the hypothesis-driven striatal and default-mode network masks, poor responders had smaller regional volumes of the left putamen as well as larger precuneus volumes compared to good responders at baseline. The machine learning approach identified that volumetric information among these two regions alongside the left frontoparietal regions, occipital lobes, and posterior/inferior cerebellum could predict clinical responses to methylphenidate in individuals with ADHD.

CONCLUSION

Our results suggest regional striatal and precuneus gray matter volumes play a critical role in mediating treatment responses in individuals with ADHD.

Significance of thymus differential ratio in immunologic status of graft tolerance

LEW with BDE-heart graft received 0 (control), 15, or 40 mg cyclosporine (CsA)/kg b. wt. per day. On postoperative days 3, 5, 7, 10, and 14 in four animals each weight and cell count of thymus and spleen were determined, and thymus and spleen cell subpopulations were examined with monoclonal antibodies. The same tests were performed in FiS heart graft recipients without immunosuppression and ungrafted LEW which received 15 or 40 mg CsA. We expressed alterations in thymocyte subpopulations by using the differentiation ratio (DR), i.e., differentiated in % of all T-cells and by the ratio of helper to suppressor/cytotoxic T-cells (Th-Ts/c). In graft rejection the thymus showed no significant change in DR or Th-Ts/c. However, in the CsA-induced graft tolerance DR was elevated and at the same time Th-Ts/c declined, both showing maximum values on days 5 and 7 and a return to normal thereafter. FiS graft recipients exhibited similar thymus alterations as tolerant recipients, but less marked. In CsA-treated ungrafted LEW, elevation of DR was slight after 15 mg but very strong after 40 mg CsA (93% on day 7), and it did not return to normal in the latter group. Th-Ts/c was decreased in these ungrafted animals, but not as strongly as in tolerant graft recipients. Such thymus alterations were not observed in graft rejection. Spleen weights were strongly increased in graft rejection and unchanged in graft tolerance. Splenic Ts/c and Th-Ts/s were increased in CsA-treated tolerant recipients but not in graft rejection. We conclude that elevation of DR and decline of thymic Th-Ts/c in the initial postoperative phase are indicators of graft tolerance in organ recipients.