A worldwide study of white matter microstructural alterations in people living with Parkinson's disease.

The progression of Parkinson's disease (PD) is associated with microstructural alterations in neural pathways, contributing to both motor and cognitive decline. However, conflicting findings have emerged due to the use of heterogeneous methods in small studies. Here we performed a large diffusion MRI study in PD, integrating data from 17 cohorts worldwide, to identify stage-specific profiles of white matter differences. Diffusion-weighted MRI data from 1654 participants diagnosed with PD (age: 20-89 years; 33% female) and 885 controls (age: 19-84 years; 47% female) were analyzed using the ENIGMA-DTI protocol to evaluate white matter microstructure. Skeletonized maps of fractional anisotropy (FA) and mean diffusivity (MD) were compared across Hoehn and Yahr (HY) disease groups and controls to reveal the profile of white matter alterations at different stages. We found an enhanced, more widespread pattern of microstructural alterations with each stage of PD, with eventually lower FA and higher MD in almost all regions of interest: Cohen's d effect sizes reached d = -1.01 for FA differences in the fornix at PD HY Stage 4/5. The early PD signature in HY stage 1 included higher FA and lower MD across the entire white matter skeleton, in a direction opposite to that typical of other neurodegenerative diseases. FA and MD were associated with motor and non-motor clinical dysfunction. While overridden by degenerative changes in the later stages of PD, early PD is associated with paradoxically higher FA and lower MD in PD, consistent with early compensatory changes associated with the disorder.

Ex Vivo Vascular Imaging and Perfusion Studies of Normal Kidney and Tumor Vasculature.

This work describes a comprehensive study of the vascular tree and perfusion characteristics of normal kidney and renal cell carcinoma. Methods: Nephrectomy specimens were perfused ex-vivo, and the regional blood flow was determined by infusion of radioactive microspheres. The vascular architecture was characterized by micronized barium sulphate infusion. Kidneys were subsequently sagitally sectioned, and autoradiograms were obtained to show the perfusate flow in relation to adjacent contact X-ray angiograms. Vascular resistance in defined tissue compartments was quantified, and finally, the tumor vasculature was 3D reconstructed via the micro-CT technique. Results show that the vascular tree of the kidney could be distinctly defined, and autoradiograms disclosed a high cortical flow. The peripheral resistance unit of the whole perfused specimen was 0.78 ± 0.40 (n = 26), while that of the renal cortex was 0.17 ± 0.07 (n = 15 with 114 samples). Micro-CT images from both cortex and medulla defined the vascular architecture. Angiograms from the renal tumors demonstrated a significant vascular heterogeneity within and between different tumors. A dense and irregular capillary network characterized peripheral tumor areas, whereas central parts of the tumors were less vascularized. Despite the dense capillarity, low perfusion through vessels with a diameter below 15 µm was seen on the autoradiograms. We conclude that micronized barium sulphate infusion may be used to demonstrate the vascular architecture in a complex organ. The vascular resistance was low, with little variation in the cortex of the normal kidney. Tumor tissue showed a considerable vascular structural heterogeneity with low perfusion through the peripheral nutritive capillaries and very poor perfusion of the central tumor, indicating intratumoral pressure exceeding the perfusion pressure. The merits and shortcomings of the various techniques used are discussed.

Family History and Risk of Renal Cell Carcinoma: A National Multiregister Case-Control Study.

PURPOSE: Our purpose was to investigate the association between family history of renal cell carcinoma (RCC) and RCC risk. MATERIALS AND METHODS: RCC cases diagnosed in Sweden between 2005 and 2014 and 10 matched controls were identified using the Renal Cell Cancer Database Sweden, with linkage to the Multigeneration Register and the Swedish Cancer Registry. The association between a family history of RCC and RCC was investigated, overall and by sex and age groups. RESULTS: Among 9416 RCC cases, 294 (3.1%) had 1 or more parent or sibling (first-degree relative [FDR]) with RCC. Median age at diagnosis for cases with an affected FDR was 65 years (IQR 59-71) and 68 years (IQR 60-75) for all cases. The proportion of women was significantly higher among familial RCC compared to sporadic RCC (44.6% vs 38.5%, P = .035). RCC was twice as likely with 1 or more FDR with RCC (OR 1.9; CI 1.65-2.16). Stratified analysis showed an OR of 2.4 for women (CI 1.93-2.92) and 1.6 for men (CI 1.35-1.93). Two or more FDRs was associated with a sixfold increased risk (95% CI 2.37-15.5). Familial RCC was strongly associated with bilateral and multifocal tumors (OR 5.5; CI 2.36-13.0, OR 3.5; CI 1.89-6.49). CONCLUSIONS: In this Swedish data set, 3.1% of RCC patients have 1 or more FDR diagnosed with RCC. There was no statistical difference in median age between sporadic RCC and familial RCC. Having 1 or more FDR with RCC approximately doubles the risk of RCC with a higher risk increase for women than for men. People with 2 FDRs with RCC constitute a small high-risk group that may benefit from screening.