Hepatic Autophagy Deficiency Compromises Farnesoid X Receptor Functionality and Causes Cholestatic Injury.

Autophagy is important for hepatic homeostasis, nutrient regeneration, and organelle quality control. We investigated the mechanisms by which liver injury occurred in the absence of autophagy function. We found that mice deficient in autophagy because of the lack of autophagy-related gene 7 or autophagy-related gene 5, key autophagy-related genes, manifested intracellular cholestasis with increased levels of serum bile acids, a higher ratio of tauromuricholic acid/taurocholic acid in the bile, increased hepatic bile acid load, abnormal bile canaliculi, and altered expression of hepatic transporters. In determining the underlying mechanism, we found that autophagy sustained and promoted the basal and up-regulated expression of farnesoid X receptor (Fxr) in the fed and starved conditions, respectively. Consequently, expression of Fxr and its downstream genes, particularly bile salt export pump, and the binding of FXR to the promoter regions of these genes, were suppressed in autophagy-deficient livers. In addition, codeletion of nuclear factor erythroid 2-related factor 2 (Nrf2) in autophagy deficiency status reversed the FXR suppression. Furthermore, the cholestatic injury of autophagy-deficient livers was reversed by enhancement of FXR activity or expression, or by Nrf2 deletion. Conclusion: Together with earlier reports that FXR can suppress autophagy, our findings indicate that autophagy and FXR form a regulatory loop and deficiency of autophagy causes abnormal FXR functionality, leading to the development of intracellular cholestasis and liver injury.

Clear cell renal cell carcinoma with a syncytial-type multinucleated giant tumor cell component: implications for differential diagnosis.

A component of syncytial-type multinucleated tumor giant cells is uncommon in clear cell renal cell carcinoma, and the histogenesis, incidence, and clinical implications of this finding are not well understood. We retrieved 13 such tumors from our pathology archives in patients with a median age of 60years, comprising 1.5% of clear cell renal cell carcinomas. Stage was typically pT4 or pT3 (each 38%). Microscopically, all tumors included a component of low-grade clear cell renal cell carcinoma with usual features. Syncytial-type giant tumor cells possessed voluminous cytoplasm, usually granular and eosinophilic, and numerous nuclei similar to those of the mononuclear tumor cells. Transition between areas of mononuclear and multinucleated cells was sometimes abrupt. Other findings included necrosis (77%), hyaline globules (46%), emperipolesis (46%), and intranuclear cytoplasmic invaginations (23%). Immunohistochemical staining typically revealed both mononuclear and multinucleated cells to be positive for carbonic anhydrase IX, CD10, epithelial membrane antigen, vimentin, and cytokeratin AE1/AE3 and negative for ß human chorionic gonadotropin, TFE3, cathepsin K, cytokeratin 7, cytokeratin 20, HMB45, CD68, smooth muscle actin, and S100. Most patients with available information (7/9) were alive with metastatic disease at the most recent follow-up. Syncytial-type giant cells are an uncommon finding associated with aggressive clear cell renal cell carcinomas. Despite the unusual appearance of this tumor component, its immunoprofile supports an epithelial lineage and argues against trophoblastic, osteoclast-like, or histiocytic differentiation. Reactivity for typical clear cell renal cell carcinoma antigens facilitates discrimination from giant cells of epithelioid angiomyolipoma or other tumors, particularly in a biopsy specimen or a metastatic tumor.

Electron microscopic analysis of a spherical mitochondrial structure.

Mitochondria undergo dynamic structural alterations to meet changing needs and to maintain homeostasis. We report here a novel mitochondrial structure. Conventional transmission electron microscopic examination of murine embryonic fibroblasts treated with carbonyl cyanide m-chlorophenylhydrazone (CCCP), a mitochondrial uncoupler, found that more than half of the mitochondria presented a ring-shaped or C-shaped morphology. Many of these mitochondria seemed to have engulfed various cytosolic components. Serial sections through individual mitochondria indicated that they formed a ball-like structure with an internal lumen surrounded by the membranes and containing cytosolic materials. Notably, the lumen was connected to the external cytoplasm through a small opening. Electron tomographic reconstruction of the mitochondrial spheroids demonstrated the membrane topology and confirmed the vesicular configuration of this mitochondrial structure. The outside periphery and the lumen were defined by the outer membranes, which were lined with the inner membranes. Matrix and cristae were retained but distributed unevenly with less being kept near the luminal opening. Mitochondrial spheroids seem to form in response to oxidative mitochondrial damage independently of mitophagy. The structural features of the mitochondrial spheroids thus represent a novel mitochondrial dynamics.

Malignant Brenner tumor of the ovary with transformation to trabecular carcinoid: an immunocytochemical and electron microscopic study.

Ovarian Brenner tumors are typically of surface epithelial-stromal origin; however, cases associated with mature cystic teratoma and/or struma ovarii possibly have a teratomatous derivation. Although argyrophil cells have been described in ovarian Brenner tumors and in urinary bladder epithelium, we are not aware of any previous reports of carcinoid arising from a malignant Brenner tumor of the ovary. In this study, we describe an 85-year-old woman who had a low-grade malignant Brenner tumor with progressive proliferation of neuroendocrine cells and transformation to trabecular carcinoid as demonstrated by immunocytochemistry and electron microscopy.

Bacterial adherence to surgical sutures: can antibacterial-coated sutures reduce the risk of microbial contamination?

BACKGROUND: Surgical site infections are associated with severe morbidity and mortality. The role of surgical sutures in the etiology of surgical site infection has been the objective of discussion for decades. This study used a standardized in vitro microbiologic model to assess bacterial adherence and the antibacterial activity of a triclosan-coated polyglactin 910 (braided) suture against selected Gram-positive and Gram-negative clinical isolates that may infect surgical wounds. STUDY DESIGN: Standardized cultures (2.0 log(10) colony forming units/mL and 5.0 log(10) colony forming units/mL of three clinical strains, Staphyllococcus aureus (methicillin-resistant S aureus [MRSA]), S epidermidis (biofilm-positive) and Escherichia coli (extended-spectrum beta-lactamase [ESBL]-producer) were inoculated to triclosan-coated and noncoated polyglactin 910 sutures to evaluate comparative adherence of bacterial isolates to the antibacterial coated and noncoated surgical sutures; to assess the impact of serum proteins (bovine serum albumin) on antibacterial activity of triclosan-coated suture; and to document the duration of antibacterial activity of the triclosan-coated material. Selected suture samples were prepared for scanning electron microscopy to demonstrate bacterial adherence. RESULTS: Substantial (p < 0.01) reductions in both Gram-positive and Gram-negative bacterial adherence were observed on triclosan-coated sutures compared with noncoated material. Pretreatment of surgical sutures with 20% BSA did not diminish antibacterial activity of the triclosan-coated braided device compared with noncoated suture (p < 0.01), and antibacterial activity was documented to persist for at least 96 hours compared with controls (p < 0.01). CONCLUSIONS: The in vitro model demonstrated a considerable reduction (p < 0.01) in Gram-positive and Gram-negative bacterial adherence to a triclosan-coated braided suture, which was associated with decreased microbial viability (p < 0.001). Because bacterial contamination of suture material within a surgical wound may increase the virulence of a surgical site infection, treating the suture with triclosan provides an effective strategy for reducing perioperative surgical morbidity.

Impact of selective antimicrobial agents on staphylococcal adherence to biomedical devices.

BACKGROUND: Infection of intravascular or implanted biomedical devices often involves biofilm-forming staphylococci that are recalcitrant to antimicrobial therapy. The present study investigated the activity of 6 antimicrobial agents against biofilm-forming and non-biofilm-forming strains of staphylococci adherent to the surface of selected biomedical devices. METHODS: Five clinical staphylococcal strains were selected for study in (1) antibiotic-lock model (ALM) and (b) vascular graft model (Dacron and expanded polytetrafluoroethylene [ePFTE]) devices. Test strains were inoculated for 30 minutes to stabilize microbial adherence and then exposed to antibiotic; the impact on bacterial adherence was assessed at 1, 2, 4, 7, and 10 days. RESULTS: Regarding ALM, daptomycin and rifampin were effective at eradicating staphylococcal adherence by day 4 (P<.01); linezolid and gentamicin by day 7 (P<.01); vancomycin by day 7; and ceftriaxone failed to eradicate staphylococcal adherence in 4 of 5 strains by day 10. Regarding ePTFE, daptomycin and linezolid eradicated staphylococcal adherence by day 2 (P<.01); rifampin by day 4 (P<.01); vancomycin and gentamicin by day 7 (P<.01); and ceftriaxone failed to eliminate staphylococcal adherence in 3 of 5 strains by day 10. Regarding Dacron, daptomycin and rifampin eradicated adherent strains by day 4 (P<.01); linezolid by day 7 (P<.01), and vancomycin, gentamicin, and ceftriaxone decreased staphylococcal adherence by 90%, 95%, and 78%, respectively, by day 10. COMMENTS: Daptomycin, rifampin, and linezolid demonstrated greater efficacy and speed in eradicating microbial adherence of staphylococcal isolates from selected devices compared with vancomycin, gentamicin, or ceftriaxone (P<.01). Further studies are warranted, however, to validate the clinical efficacy of daptomycin and linezolid in the treatment of biomedical device-associated infections.

Bednar tumor: report of a case with immunohistochemical and ultrastructural study.

A slowly growing tumor in the right shoulder of a 38-year-old white male, which felt like a superficial cystic mass, was studied. The spindle cells, which represented the main component of the tumor, were arranged in a typical storiform pattern and were positive for CD34 and focally for CD117. The pigmented cells were mostly found at the center of the storiform whorls and were negative for S-100 protein and HMB-45. Ultrastructurally, the tumor consisted predominantly of nondescript mesenchymal spindle cells that resembled fibroblasts. The tumor cells blended into a loosely arranged stromal tissue background. The general appearance of pigmented cells was very similar to the nonpigmented spindle cells. The pigment appeared to be a mature form of melanin granules. The lack of premelanosomes, cell injections, basal lamina, and pinocytotic vesicles was inconsistent with a neural origin/neural differentiation hypothesis for this tumor.