Normal and disrupted lumbar longitudinal ligaments: correlative MR and anatomic study

The posterior and anterior longitudinal ligaments of the lumbar spine appear on magnetic resonance (MR) images as thin lines of very low signal intensity in all spin-echo sequences. They cover the periphery of the outer fibers of the anulus fibrosus on sagittal images. The lumbar spine of 17 patients with 19 disk herniations was prospectively evaluated with MR imaging, and these findings were correlated with surgical findings. At surgery the posterior ligament was found to be disrupted in eight cases and intact in 11. Absence of a low-signal peripheral line around the herniated nucleus pulposus (HNP) was the most reliable sign of ligament rupture (no false-negative or false-positive findings). The peripheral line appeared to be interrupted in four cases, two of which were falsely positive. The two false-positive cases were related to a chemical shift artifact between epidural fat and the HNP. Presence of a normal and continuous peripheral line outlining the HNP excluded ligament disruption. The overall sensitivity for detecting disruption was 100%, and the specificity was 78%.     

Relationship between peptide binding and T cell epitope selection: a study with subtypes of HLA-B27

The effect of HLA-B27 polymorphism on antigen presentation was analysed by comparing the binding of three Epstein-Barr virus-derived peptide epitopes to HLA-B27 subtypes with their immunogenicity and antigenicity in the context of these subtypes. The effect of altering the major anchor residue Arg2 on binding or on recognition by peptide-specific cytotoxic T lymphocytes (CTL) was also examined. The three peptides bound significantly to all the B*2701-B*2706 subtypes. This did not correlate with the peptides being immunogenic or recognized by specific CTL in the context of only particular subtypes. In addition, of the three viral epitopes tested, those that were immunogenic in B*2702- or B*2705-restricted responses bound to these subtypes less efficiently than one peptide that was immunogenic only in the B*2704 context. Thus, among several potentially immunogenic peptides from the same virus, the antiviral response is not necessarily directed against the one that binds best to the restricting subtype. These results indicate that HLA- B27 polymorphism influences antigen presentation in ways other than simply peptide affinity. Synthetic analogues lacking the canonical Arg2 motif of HLA-B27-bound peptides, even when binding much worse to the restricting subtype, were recognized equally by CTL specific for the parental peptide. This indicates that Arg2 is not required to maintain the structure of the epitope. The implications of these results for pathogenetic models of HLA-B27-associated disease are discussed.      

Positive margins in basal cell carcinoma: relationship to clinical features and recurrence risk. A retrospective study of 248 patients

BACKGROUND: Incomplete resection of a basal cell carcinoma does not necessarily imply tumour recurrence. OBJECTIVE: The purpose of our study was to determine the clinical features most often associated with positive surgical margins and to establish whether positive margins effectively imply tumour recurrence. METHODS: We did a retrospective evaluation of 273 basal cell carcinomas in a total of 248 subjects. For each case, data regarding tumour location, sex, histological type and the presence or absence of affected surgical margins were collected. Follow-up was available in 151 cases. RESULTS: Positive margins were most often observed in facial lesions, particularly in the nasal and perioral areas, and for morphoeic histological types. Tumours with margin involvement exhibited a higher recurrence rate (26%) than those with free margins (14%) over a 5-year follow-up period. CONCLUSIONS: Individualized management, with special considerations depending on tumour location and histological type, is needed to treat basal cell carcinomas and cases with affected margins. Re-excision, preferably with Mohs' surgery, is advised in the latter as recurrences are much more complicated to treat. Furthermore, all cases need adequate follow-up, even in cases with unaffected surgical margins.     

Role of endothelial cells in restenosis after coronary angioplasty

Summary— Percutaneous transluminal coronary angioplasty (PTCA) is today a procedure of choice in many patients with atherosclerotic coronary artery disease. Despite high rates of initial success, restenosis, occurring in 30 to 40 percent of patients within the first six months, remains the major problem limiting the long-term efficacy of the procedure. Animal models have enhanced our knowledge in the understanding of the mechanisms involved in the restenotic process after experimental angioplasty. In fact, the two known determinants of restenosis are the proliferative and migrative response of underlying smooth muscle cells with production of extracellular matrix and the recently highlighted vascular remodeling. Endothelium, which regenerates from the leading edge of the de-endothelialized area within the weeks following arterial injury, is of particular interest in the modulation of the healing process after the procedure. Endothelial dysfunction, as an imbalance between relaxing and contracting factors, between anti- and procoagulant mediators or growth-inhibiting and growth-promoting factors, occurs at sites of regenerating endothelium. Experimental studies, using drugs that enhance endothelium-derived relaxing factors release or drugs that diminish endothelium-derived contracting factors production, have often been shown to be effective in the restenosis prevention. Thus, impairment in endothelial cell function may be considered as one of the major regulatory element in the restenotic process. This review discusses the interactions between endothelial and smooth muscle cells and has for aim to point out the major role of endothelial cells in the development of neointimal thickening and arterial remodeling.     

The relationship of blood transfusion, tumor staging, and cancer recurrence

Previous research demonstrated a relationship between transfusions of whole blood, or large numbers of red cell concentrates, and later recurrence of cancers of the colon, rectum, cervix, and prostate. It is possible that the transfusion of whole blood may represent a surrogate marker for advanced or more aggressive clinical disease. The relationship of clinical or histologic tumor stage, blood transfusion status, and disease outcome was studied in detail. Patients receiving no transfusions or small numbers of red cells (less than or equal to 3 units) had uniformly better recurrence and survival experiences than patients receiving similar amounts of blood that included at least 1 unit of whole blood, regardless of the patient's clinical or histologic tumor stage. In multivariate analyses, stage was an independent predictor of outcome, and transfusion status was not a surrogate marker for stage. The effects on recurrence of stage and transfusion appear to be cumulative. These results are consistent with but do not prove the hypothesis that the transfusion of large amounts of stored plasma and cellular debris impairs the host defenses against cancer, regardless of the underlying biologic and clinical aggressiveness of the cancer.