Background & Aims Hepatocellular ballooning is a key finding in nonalcoholic steatohepatitis (NASH). It is conventionally defined by hemotoxylin and eosin (H&E) staining showing enlarged cells with rarefied cytoplasm and recently by changes in the cytoskeleton. Fat droplets are emerging as important organelles in cell metabolism. To address a possible relation between fat droplets and ballooning, we studied fat staining, H&E, and keratin 18 staining in human NASH. Methods Sequential staining and high resolution imaging were used to study freshly prepared cryo-sections from 10 patients with histologically confirmed steatohepatitis using oil red O for fat droplet identification, H&E to identify ballooning, and anti-K18 to confirm cytoskeletal changes. High resolution images were captured at each stage using the Aperio Scanscope. To provide ultrastructural correlation, glutaraldehyde-fixed specimens were studied using transmission electron microscopy (TEM) with serial sectioning for localization of ballooned cells by light microscopy and TEM in identical specimens. Results Serial staining consistently demonstrated that hepatocellular ballooning is associated with fat droplet accumulation evident by oil red O positivity and depletion of cytoplasmic keratin 18 with K-18 positive Mallory-Denk bodies (MDB). TEM confirmed the association between osmium stained fat droplets, MDB formation and cellular enlargement and suggested droplet-associated dilation of the endoplasmic reticulum. Conclusion These results indicate a relationship between cellular ballooning, fat droplet accumulation and cytoskeletal injury in NASH. We speculate that injury to multiple organelles including fat droplets and endoplasmic reticulum contribute to this characteristic finding.

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Study DesignRetrospective comparative study.PurposeTo compare the incidence of proximal junctional kyphosis (PJK) between transverse process hooks (TPHs) and pedicle screws (PSs) at the upper instrumented vertebrae (UIV) following adult spinal deformity (ASD) surgery.Overview of LiteratureThe choice of UIV implant type may be important for avoiding PJK; however, few comparative clinical studies have evaluated the incidence of PJK according to the type of UIV implant used in ASD surgery.MethodsWe retrospectively reviewed 39 consecutive patients with ASD (mean age, 67 years; mean follow-up period, 41 months) who underwent corrective surgery between 2009 and 2013. TPH was used in 17 patients and PS in 22 patients. PJK was defined as the presence of a UIV or UIV±1 fracture, or a change in the proximal junctional angle (PJA) of >20°. Data of patients with TPH and PS were compared.ResultsThe TPH group had a PJK incidence of 17.6% compared with 27.3% in the PS group (p =0.47). In the TPH group, PJK was a result of UIV fracture in one patient, UIV−1 fracture in one patient, and ligamentous failure in one patient. In the PS group, six patients developed PJK because of UIV fracture. No differences in radiographic parameters were found between the two groups. After analyzing the PJA data in the patients with PJK, the changes in PJA were significantly higher in the PS group than in the TPH group (19.0°/5.0°, p =0.04).ConclusionsOur results show that using TPH as a UIV implant may not prevent PJK; however, using TPH as the UIV anchor may prevent vertebral collapse if cases of UIV fracture. The increased risk of UIV fracture collapse in the PS group may be a result of a higher mechanical load on UIV when using PS.

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