Assessment of HOPE fixation in vitrectomy specimens in patients with chronic bilateral uveitis (masquerade syndrome)

Background Cytological examination of rapidly transported, unfixed vitreous specimens is considered the gold standard in exclusion of primary intraocular lymphoma (PIOL) in patients with idiopathic steroid resistant chronic uveitis. These specimens are difficult to interpret, and reports of false negatives or false positives are common. Fixation using HOPE solution (Herpes-glutamic acid buffer mediated Organic solvent Protection Effect) has been successfully applied in the investigation of cytospin preparations using immunocytology, in situ hybridisation and polymerase chain reaction (PCR). The purpose of this study was to compare the cytologic features of vitrectomy specimens from patients with clinical reactive vitritis and PIOL prepared following HOPE fixation with those in conventional cytospins and to identify any diagnostic pitfalls.Methods Pars plana vitrectomy was performed in 15 cases of patients with chronic uveitis. The vitreous samples were halved: one half was fixed in HOPE solution; the other half remained unfixed. All samples were subject to conventional staining, immunocytology and clonality analysis using polymerase chain reaction (IgH-PCR) and GeneScan. The specimens were assessed following by two pathologists who were masked to the cytological preparation method. The specimens were evaluated for cellularity, cellular appearance, cytoplasmic and nuclear features as well as quality of the immunostains.Results Twelve of the fifteen vitreous samples were diagnosed as reactive vitritis; in three specimens, a primary intraocular lymphoma of B-cell type was diagnosed. Compared to the unfixed vitreal specimens, the quality of the cytomorphology and immunocytology improved in the HOPE-fixed specimens. IgH-PCR and GeneScan analysis demonstrated polyclonal amplification products in the reactive cases, and monoclonal B-cell populations in the B-PIOL.Conclusion Our results demonstrate that cytomorphology and immunoreactivity of vitreous specimens are well preserved following HOPE fixation. DNA of sufficient quality could be extracted from HOPE-fixed vitreous biopsies, in order to perform clonality analyses. HOPE fixation appears to be promising in simplifying the transportation of these specimens, and may improve the diagnostic reliability of vitreous specimens in patients with masquerade syndrome.     

Is prior knowledge of object geometry used in visually guided reaching?

We investigated whether humans use prior knowledge of the geometry of faces in visually guided reaching. When viewing the inside of a mask of a face, the mask is often perceived as being a normal (convex) face, instead of the veridical, hollow (concave) shape. In this "hollow-face illusion," prior knowledge of the shape of faces dominates perception, even when in conflict with information from binocular disparity. Computer images of normal and hollow faces were presented, such that depth information from binocular disparity was consistent or in conflict with prior knowledge of the geometry. Participants reached to touch either the nose or cheek of the faces or gave verbal estimates of the corresponding distances. We found that reaching to touch was dominated by prior knowledge of face geometry. However, hollow faces were estimated to be flatter than normal faces. This suggests that the visual system combines binocular disparity and prior assumptions, rather than completely discounting one or the other. When comparing the magnitude of the hollow-face illusion in reaching and verbal tasks, we found that the flattening effect of the illusion was similar for verbal and reaching tasks.     

The dynamics of visual pattern masking in natural scene processing: a magnetoencephalography study

We investigated the dynamics of natural scene processing and mechanisms of pattern masking in a scene-recognition task. Psychophysical recognition performance and the magnetoencephalogram (MEG) were recorded simultaneously. Photographs of natural scenes were briefly displayed and in the masked condition immediately followed by a pattern mask. Viewing the scenes without masking elicited a transient occipital activation that started approximately 70 ms after the pattern onset, peaked at 110 ms, and ended after 170 ms. When a mask followed the target an additional transient could be reliably identified in the MEG traces. We assessed psychophysical performance levels at different latencies of this transient. Recognition rates were reduced only when the additional activation produced by the pattern mask overlapped with the initial 170 ms of occipital activation from the target. Our results are commensurate with an early cortical locus of pattern masking and indicate that 90 ms of undistorted cortical processing is necessary to reliably recognize a scene. Our data also indicate that as little as 20 ms of undistorted processing is sufficient for above-chance discrimination of a scene from a distracter.     

Reversal of glucose-insulin-potassium-induced hyperglycemia by aggressive insulin treatment in postoperative heart failure. An observational study

Metabolic support with glucose-insulin-potassium (GIK) significantly reduces the morbidity and mortality of patients in cardiogenic shock after hypothermic ischemic arrest for aortocoronary bypass surgery. However, a small subset of these patients develops postoperative insulin resistance regardless of their preoperative diabetic status. Whether GIK directly contributes to higher mortality in these patients is unknown. We reviewed the records of 322 patients whose treatment for postoperative cardiogenic shock included GIK. Ten patients (3%) had postoperative hyperglycemia (serum glucose > or =250 mg/dl or 13.9 mmol/l) due to insulin resistance. These were compared to randomly selected GIK-treated, insulin-responsive patients (n = 10) and non-GIK-treated patients (n = 10) for comparison. The insulin-resistant patients required increasing amounts of regular insulin up to 130 U/h until blood glucose levels fell below 250 mg/dl. However, short-term outcomes (IABP support time, length of stay in ICU, 7-day mortality) for insulin- resistant patients were indistinguishable from those for insulin-responsive patients. These data indicate that postoperative iatrogenic hyperglycemia in patients after cardiopulmonary bypass may not be detrimental per se and is reversible when treated with supplemental insulin.     

Reliable detection of epigenetic histone marks and nuclear proteins in tissue cryosections

Nuclear processes in real tissues often are significantly different from those in cultured cells. However, immunostaining on tissue sections needs long fixation which masks antigens and, respectively, antigen retrieval which restores antigen accessibility. These treatments affect the immunostaining results and complicate their interpretation. The problem is especially significant for nuclear antigens which often are very sensitive to both fixation and antigen retrieval. We targeted this problem by a study of several histone modifications and nuclear proteins in tissue sections of mouse retina which contains cells with both conventional and unique inverted nuclei. In the latter, the main chromatin classes form separate concentric shells which simplifies evaluation of the signal distribution. We show that as a rule, longer fixation demands longer antigen retrieval time. Nevertheless, antigens are remarkably diverse in this respect and need individual adjustment. We suggest a robust procedure for immunostaining on sections, that is, a method that allows controlling the differences in immunostaining caused by differences in fixation time and antigen retrieval duration, so that immunostaining protocol can be quickly optimized.     

Cytokeratin-positive epithelioid angiosarcoma presenting in the tonsil: a diagnostic challenge

Primary oral cavity sarcomas are exceedingly rare and may pose a great diagnostic challenge. A 71-year-old woman without history of malignancy or radiation to the head and neck presented with an antibiotic-refractory diffuse painful swelling of the right tonsil necessitating tonsillectomy. Histologic evaluation revealed subtotal replacement of the right tonsil by a high-grade epithelioid neoplasm displaying extensive ulceration, necrosis, and primitive vasoformation. Immunohistochemistry showed strong/diffuse expression of pancytokeratin antibodies KL-1 and Lu5, cytokeratin 8, cytokeratin 18, cytokeratin 19, vimentin, CD31, ERG, and Freund leukemia integration site 1 (FLI-1). High-molecular-weight cytokeratins (cytokeratin 5, 34β12), cytokeratin 7, cytokeratin 13, and cytokeratin 20 were not expressed. Within months, the patient underwent surgical resection of multiple bleeding intraoral and gastrointestinal metastases. She is currently alive with disease 9 months from diagnosis. To our knowledge, this case represents the first well-documented primary epithelioid angiosarcoma of the tonsil. The strong cytokeratin expression in epithelioid angiosarcomas represents a diagnostic pitfall. Thus, awareness of this rare and highly aggressive neoplasm is necessary for distinguishing it from poorly differentiated and acantholytic squamous cell carcinoma and diffuse large cell lymphoma.