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INTRODUCTION AND IMPORTANCE: Total hip arthroplasty is one of the most performed surgical interventions in the world. Adverse local tissue reactions and pseudotumors are infrequent but dangerous eventualities, which are often related with metal-on-metal or metal-on-polyethylene implants. This study wants to highlight how adverse local tissue reactions and pseudotumors must be taken into consideration during the diagnostic process. CASE PRESENTATION: We report the case of a patient with ceramic-on-ceramic modular total hip arthroplasty with titanium neck. 12 years after surgery, he complained of pain and swelling on the hip. Diagnostic tests revealed the presence of a bulky pseudotumor. During the revision surgery biopsy samples were taken and microscopical analysis revealed the presence of fibrous tissue, fibrin hemorrhagic collections, histiocytes and chronic inflammation due to foreign body, with dark refractive material of an exogenous nature. CLINICAL DISCUSSION: The possible formation of pseudotumor and metallosis reactions in hip prostheses with metal-on-metal coupling or in couplings with polyethylene is known. Many cases of pseudotumor are reported after revision of prostheses due to the breakage of ceramic components, but we did not observe any damage or corrosion of the prosthetic elements; on the other hand, we noticed an excessive retroversion of the femoral neck. It may be possible that an accurate microscopic analysis could clarify the failure of this implant. CONCLUSION: To date ceramic-ceramic coupling remains the gold standard in terms of resistance and durability for hip arthroplasty but there is still a gap of knowledge in the field of tribology and individual immune response mechanisms.

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BACKGROUND: Prosthetic valve endocarditis presents unique challenges for both diagnosis and treatment. A potential role of biofilm has been hypothesized in the pathogenesis of these infections. METHODS: A patient with infective endocarditis involving a stentless (Freestyle) porcine prosthetic aortic valve with annular abscess and paravalvular leak 8 months after implantation is reported. RESULTS: The infected valve did not show vegetations or perforations, but histiocytic inflammation was seen along the endocardial surfaces of the valve. Auramine-rhodamine staining revealed many acid-fast organisms associated with the inflammation. There was also an acellular matrix material with ultrastructural features of biofilm. Blood cultures grew Mycobacterium fortuitum, a biofilm-associated microbe. CONCLUSIONS: The role of biofilm in prosthetic valve endocarditis is discussed. The importance of microscopy for prosthetic valves, even when no vegetations are present, is highlighted along with correlation of pathologic findings with culture results.

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Multicentric osteosarcoma (M-OGS) is characterized by multicentricity of osseous osteosarcomas, either synchronous or metachronous, without visceral involvement. The study's purpose was to clinicopathologically and radiographically analyze 56 cases of M-OGS (22 synchronous and 34 metachronous). The distal femur was the most common site. Histologically, all tumors were high grade. Of 22 patients with synchronous M-OGS, 16 had 3 or more simultaneous tumors; the axial skeleton was involved in 14 (64%) of 22 cases. In metachronous M-OGS, the second malignancy occurred after a median of 22 months. Treatment was surgery, chemotherapy, radiotherapy, or a combination of these. Patients with metachronous osteosarcoma had a median survival longer than did patients with synchronous tumors. Overall, 8 long-term survivors were treated by aggressive surgery with wide margins (plus chemotherapy and/or radiotherapy). M-OGS combines multiple skeletal locations of high-grade conventional osteosarcomas and has a poor prognosis. Aggressive surgery may result in improved long-term survival, particularly in patients with metachronous disease.

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AIMS: The aim of our study was to examine the effects of statin therapy (atorvastatin) on post-implant structural changes of bovine pericardial tissue in a subcutaneous animal model. METHODS AND RESULTS: Sixty male C57BL/6 mice underwent subcutaneous dorsal implantation of bovine pericardial fragments. Animals were randomized to treatment with atorvastatin (50 mg/kg) (statin group - SG) or to vehicle (control group - CG). After 1.5 months, all fragments were explanted and submitted to histopathological assessment (semi-quantitative analysis) to elucidate extent of inflammatory infiltrate, signs of tissue injury, or presence of microcalcification. Calcium determination of the implanted pericardial tissue was also performed by inductively coupled plasma mass spectrometry (ICP-MS) assessment. ICP-MS analysis showed that pericardial fragments in SG had significantly (p<0.01) less calcium content than CG (625+/-142 vs. 962+/-590 microg/g, respectively). Light microscopy showed marked inflammatory infiltrates and tissue injury of pericardial specimens in CG animals, whereas SG animals maintained a better preserved original pericardial structure. CONCLUSIONS: Our findings indicate that atorvastatin significantly attenuates the post-implant structural degeneration of artificial valve bovine pericardial tissue in a subcutaneous animal model. Further observations are mandatory to assess the effects of statins on the implanted bioprosthetic valve tissue in the blood circulation.

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Methylation of the exocyclic amino group of guanine is a relatively common modification in rRNA and tRNA. Single methylation (N(2)-methylguanosine, m(2)G) is the second most frequently encountered nucleoside analog in Escherichia coli rRNAs. The most prominent case of dual methylation (N(2),N(2)-dimethylguanosine, m(2) (2)G) is found in the majority of eukaryotic tRNAs at base pair m(2) (2)G26:A44. The latter modification eliminates the ability of the N(2) function to donate in hydrogen bonds and alters its pairing behavior, notably vis-à-vis C. Perhaps a less obvious consequence of the N(2),N(2)-dimethyl modification is its role in controlling the pairing modes between G and A. We have determined the crystal structure of a 13-mer RNA duplex with central tandem m(2) (2)G:A pairs. In the structure both pairs adopt an imino-hydrogen bonded, pseudo-Watson-Crick conformation. Thus, the sheared conformation frequently seen in tandem G:A pairs is avoided due to a potential steric clash between an N(2)-methyl group and the major groove edge of A. Additionally, for a series of G:A containing self-complementary RNAs we investigated how methylation affects competitive hairpin versus duplex formation based on UV melting profile analysis.

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Cardiac involvement in Morquio syndrome, mucopolysaccharidosis IV, is characterized by aortic and mitral valve thickening and infiltration of the coronary arteries. There are few reports concerning surgical interventions in patients with mucopolysaccharidoses. We report a case of a patient affected by Morquio syndrome who underwent aortic valve replacement surgery for severe aortic valve stenosis, with an uneventful postoperative course. Cardiac surgery appears safe and feasible in these patients and improves the quality of life, even if the future prognosis related to the underlying disorder should be considered.

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Atrial fibrillation becomes a self-perpetuating arrhythmia as a consequence of electrophysiologic and structural remodeling involving the atrium. Oxidative stress may be a link between this rhythm disturbance and electrophysiologic remodeling. The aim of this study was to evaluate whether the heme oxygenase-1 (HO-1) marker of oxidative stress was more expressed in left atrial sites with stronger structural remodeling in patients affected by chronic atrial fibrillation (CAF) and mitral valve disease (MD). Myocardial samples were taken from the left atrial posterior wall (LAPW) and left atrial appendage (LAA) of 24 patients with CAF-MD in addition to 10 autopsy controls. The levels of HO-1 messenger RNA (mRNA) and HO-1 protein in each pathologic LAPW and LAA were quantified using reverse transcriptase polymerase chain reaction and enzyme-linked immunosorbent assay. Furthermore, light microscopy was used to morphometrically evaluate the differential myocyte and interstitial changes in the same CAF-MD LAPW and LAA samples. In controls, HO-1 protein was quantified using enzyme-linked immunosorbent assay. Unlike controls, patients with CAF-MD had higher levels of HO-1 mRNA and its protein product, expressed as LAPW/LAA ratios, in the LAPW (2.18 +/- 1.18, P < .0001, and 1.55 +/- 0.67, P < .005), and their LAPW also showed greater histologic changes in myocytolytic myocytes (15.1% +/- 3.1% versus 6.9% +/- 3.3%, P < .0001), interstitial fibrosis (8.2% +/- 2.2% versus 2.8% +/- 1.2%, P < .0001), and capillary density (816 +/- 120 number/mm(2) versus 1114 +/- 188 number/mm(2); P < .05). In addition, markers of oxidative stress were immunohistochemically studied with antinitrotyrosine and anti-iNOS antibodies. In patients with CAF-MD, the inducible enzyme HO-1 is more expressed in the left atrial areas that show greater structural remodeling. This finding strongly suggests a pathogenetic relationship between oxidative stress and the degree of histologic change.

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It has been found that the pulmonary veins and adjacent left atrial posterior wall (LAPW) are deeply involved in both the initiation and maintenance of atrial fibrillation (AF), and the identification of these high-risk sites has aroused great interest in investigating their histopathologic substrate. We used light and conventional electron microscopy to evaluate the differential myocyte and interstitial changes in LAPW and left atrial appendage (LAA) samples from 28 patients with chronic AF undergoing mitral valve surgery and from 12 autoptic controls. There were always more myocytes with loss of sarcomeres in the LAPW than in the LAA (19.9% +/- 7.7% versus 8.2% +/- 5.0%; P < .0001), and the LAPW showed more marked immunohistochemical evidence of dedifferentiation, characterized by the reexpression of smooth muscle actin. In pathological left atria, myocyte diameter in the LAPW and LAA was comparable (19.0 +/- 1.5 versus 18.5 +/- 2.0 microm; not significant) but larger than in the controls (11.9 +/- 0.8 and 12.1 +/- 1.3 microm, respectively; P < .0001). A terminal deoxynucleotidyltransferase assay did not reveal any myocyte apoptosis. The LAPW also showed more interstitial fibrosis than the LAA (7.49% +/- 3.34% versus 2.80% +/- 1.35%; P < .0001). Ultrastructural examination confirmed the presence of myocyte myocytolysis in the perinuclear area and showed changes in mitochondrial shape. In conclusion, the LAPW in patients with chronic AF related to mitral valve disease seems to be a particular anatomical site in which major myocyte and interstitial changes are concentrated, whereas the LAA is more protected. This remodeling may increase the heterogeneity of LAPW electrical conduction, thus confirming this location as an elective target for the ablation treatment of AF.

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