Correlations between APOE4 allele and regional amyloid and tau burdens in cognitively normal older individuals.

The correlations between apolipoprotein epsilon 4 (APOE4) status and regional amyloid, tau, and cortical thickness in cognitively normal elderly are not fully understood. Our cross-sectional study aimed to compare regional amyloid/tau burden, and cortical thickness according to APOE4 carrier status and assess correlations between APOE4 and Alzheimer's disease (AD)-related biomarker burdens. We analyzed 185 cognitively normal participants from the Alzheimer's Disease Neuroimaging Initiative (ADNI) cohort. Participants aged 55-90 with normal cognitive function were divided into amyloid ß-positive (Aß+) APOE4 carriers (group 1, n = 27), Aß+ APOE4 non-carriers (group 2, n = 29), and Aß- normal controls (group 0, n = 129). We compared amyloid depositions, tau depositions, and cortical thickness among the three groups and assessed correlations between APOE4 existence and imaging biomarkers adjusted for age and sex. The participants in group 2 were older than those in the other groups. The regional amyloid/tau standardized uptake value ratios (SUVRs) did not differ between groups 1 and 2, but the amyloid/tau SUVRs in most regions were numerically higher after adjusting for age difference. APOE4 allele had robust correlations with increased amyloid burden in the fronto-temporo-parietal cortical areas after adjustment for age and sex, but it had weaker and mixed correlations with the regional tau burden and did not have significant correlation with cortical thickness. We identified that the presence of APOE4 allele might be more highly associated with amyloid deposition than with other AD-related biomarkers such as tau or cortical thickness in cognitively normal elderly.

Nicardipine Effects on Renal Function During Spine Surgery.

STUDY DESIGN: Single-center, prospective, randomized, and single-blinded clinical trial was conducted in patients (n=64) undergoing anterior or posterior spinal interbody fusion. OBJECTIVE: To investigate the renal protective effect of nicardipine during deliberate hypotension for spine surgery by measuring creatinine clearance (Ccr), serum cystatin C, urine output, and fractional excretion of sodium (FENa). SUMMARY OF BACKGROUND DATA: Deliberate hypotension during spine surgery may result in ischemic tissue damage of the kidney. Nicardipine is reported to dilate the renal artery and increase glomerular filtration rate. Previous studies reported the renal protective effect of nicardipine during cardiac surgery under cardiopulmonary bypass and robot-assisted laparoscopic surgery. MATERIALS AND METHODS: Patients were randomized to receive nicardipine (nicardipine group, n=32) or normal saline (control group, n=32). Deliberate hypotension of mean arterial pressure at 50-65 mm Hg was maintained during surgery. Ccr, serum cystatin C, urine output, and FENa were measured before surgery, after surgery, and postoperative day 1 (POD1). The RIFLE (risk, injury, failure, loss, and end stage renal disease) criteria of the patients were evaluated. RESULTS: In the nicardipine group, Ccr at POD1 was increased compared with that after surgery. In both groups, serum cystatin C at POD1 was decreased compared with that before surgery and urine output at POD1 was decreased compared with that after surgery. FENa at POD1 in the control group was higher than that in the nicardipine group and was increased compared with that after surgery. Using RIFLE criteria, 6 patients in the control group and 2 patients in the nicardipine group were classified as having acute kidney injury. CONCLUSIONS: Nicardipine increased Ccr and attenuated the increase in FENa at POD1 in patients undergoing spine surgery under deliberate hypotension.

Ocular vestibular evoked myogenic potentials induced by air-conducted sound in patients with acute brainstem lesions.

OBJECTIVE: The ocular vestibular-evoked myogenic potential (oVEMP), a recently documented otolith-ocular reflex, is considered to reflect the central projections of the primary otolithic afferent fibers to the oculomotor nuclei. The aim of our study is to define air-conducted sound oVEMP abnormality in patients with acute brainstem lesions and to determine the brainstem structures involved in the generation of oVEMPs. METHODS: In response to air-conducted tone burst sounds (ACS), oVEMP was measured in 52 patients with acute brainstem lesions. Individualized brainstem lesions were analyzed by means of MRI-based voxel-wise lesion-behavior mapping, and the probabilistic lesion maps were constructed. RESULTS: More than half (n=28, 53.8%) of the patients with acute brainstem lesions showed abnormal oVEMP in response to ACS. The majority of patients with abnormal oVEMPs had lesions in the dorsomedial brainstem that contains the medial longitudinal fasciculus (MLF), the crossed ventral tegmental tract (CVTT), and the oculomotor nuclei and nerves. CONCLUSION: MLF, CVTT, and the oculomotor nuclei and nerves appear to be responsible for otolith-ocular responses in the brainstem. SIGNIFICANCE: Complemented to cervical VEMP for the uncrossed otolith-spinal function, oVEMP to ACS may be applied to evaluate the crossed otolith-ocular function in central vestibulopathies.