Novel conformation-selective alpha-synuclein antibodies raised against different in vitro fibril forms show distinct patterns of Lewy pathology in Parkinson's disease

AIMS

The aim of this study was to test the hypothesis that different conformations of misfolded α-synuclein (α-syn) are present in Parkinson's disease (PD) brain.

METHODS

Using two previously characterized conformations of α-syn fibrils, we generated new conformation-selective α-syn monoclonal antibodies (mAbs). We then interrogated multiple brain regions in a well-characterized autopsy cohort of PD patients (n = 49) with these mAbs, Syn7015 and Syn9029.

RESULTS

Syn7015 detects Lewy bodies (LBs) and Lewy neurites (LNs) formed by pathological α-syn in all brain regions tested, and is particularly sensitive to LNs and small Lewy dots, inclusions believed to form early in the disease. Further, we observed colocalization between Syn7015 and an early marker of α-syn pathology formation, phospho-Ser129-α-syn, and a lack of extensive colocalization with markers of more mature pathology. In comparison, Syn9029 detects Lewy pathology in all regions examined, but indicates significantly fewer LNs than Syn7015. In addition, colocalization of Syn9029 with later markers of α-syn pathology maturation (ubiquitin and P62) suggests that the pathology detected by Syn9029 is older. Semiquantitative scoring of both LN and LB pathology in nine brain regions further established this trend, with Syn7015 LN scores consistently higher than Syn9029 LN scores.

CONCLUSIONS

Our data indicate that different conformations of α-syn pathology are present in PD brain and correspond to different stages of maturity for Lewy pathology. Regional analysis of Syn7015 and Syn9029 immunostaining also provides support for the Braak hypothesis that α-syn pathology advances through the brain.

Indications and Use of Hydrogen Peroxide during Microvascular Flap Reconstruction Surgery: A Literature and Procedural Use Review

Microvascular flap reconstruction surgery is a limb preservation procedure performed in an effort to maintain the integrity of the lower limb and avoid amputations. Individuals facing the prospect of amputation often have long-term diabetes with multiple comorbidities, including severe peripheral vascular disease; peripheral arterial disease; chronic ulcerations; and Charcot arthropathy. Long-term clinical research has shown that these patients are at much higher risk for secondary amputations after a first amputation is performed. According to Sohn et al, Charcot and ulcer groups had 4.1 and 4.7 amputations per 100 person-years, respectively. In patients younger than 65 years old at the end of follow-up, amputation risk, relative to patients with Charcot alone, was 7 times higher for patients with ulcer alone and 12 times higher for patients with Charcot and ulcer. Patients with infected hardware, suffering from acute ulcerative conditions, may also be candidates for this type of surgery due to extensive tissue loss secondary to infection. Microvascular flap reconstruction surgery is a highly technical surgery involving the use of orthoplastic techniques, which is performed under ×3.5 loupe magnification. Due to the inability to perform this procedure with the use of a tourniquet, visibility within the field is obfuscated from continuous blood flow along the dissected muscle belly. Hydrogen peroxide (H2O2) is an excellent alternative to tourniquet use. The use of H2O2 allows additional benefits, such as visual field clearance and antisepsis.

Growth of the rat somatic sensory cortex and its constituent parts during postnatal development

We have compared the size and arrangement of the primary somatic sensory cortex (SI) and its constituent parts in juvenile (1 week old) and mature (10-12 weeks old) rats using succinic dehydrogenase histochemistry and digital image analysis. Our goal was to determine whether some regions of the maturing cortex grow more than others. To this end, we examined (1) the growth of barrels and the surrounding (interbarrel) cortex, (2) the growth of the major somatic representations within SI, and (3) the overall growth of SI compared to the neocortex as a whole. With respect to the first of these issues, SI barrels and barrel-like structures grow more than the intervening cortex. The growth of these elements varies according to region: barrels in the head representation more than double in size, whereas the barrel-like structures in the paw representations increase by only about half this amount. The growth of the major somatic representations within SI is also heterogeneous, the representation of the head enlarging to a greater extent than the representations of the paws. Thus, the ratio of the total area of head representation to the combined paw representation is 15% greater in adults than in juveniles. Finally, the primary somatic sensory cortex grows to a somewhat greater extent than the neocortex as a whole. These observations demonstrate that postnatal cortical growth is not uniform; it varies among cortical barrels and the immediately surrounding (interbarrel) cortex, among the representations of different body parts, and between SI and the rest of the neocortex. As an explanation of this differential growth, we suggest that the neuropil of metabolically (and/or electrically) more active cortical regions grows to a greater extent during maturation than that of less active regions.