Automatic fitting procedures for EPR spectra of disordered systems: matrix diagonalization and perturbation methods applied to fluorocarbon radicals.

Two types of automatic fitting procedures for EPR spectra of disordered systems have been developed, one based on matrix diagonalization of a general spin Hamiltonian, the other on 2nd order perturbation theory. The first program is based on a previous Fortran code complemented with a newly written interface in Java to provide user-friendly in and output. The second is intended for the special case of free radicals with several relatively weakly interacting nuclei, in which case the general method becomes slow. A least squares' fitting procedure utilizing analytical or numerical derivatives of the theoretically calculated spectrum with respect to the g- and hyperfine structure (hfs) tensors was used to refine those parameters in both cases. 'Rigid limit' ESR spectra from radicals in organic matrices and in polymers, previously studied experimentally at low temperature, were analyzed by both methods. Fluorocarbon anion radicals could be simulated, quite accurately with the exact method, whereas automatic fitting on, e.g. the c-C(4)F(8)(-) anion radical is only feasible with the 2nd order approximative treatment. Initial values for the (19)F hfs tensors estimated by DFT calculations were quite close to the final. For neutral radicals of the type XCF(2)CF(2)* the refinement of the hfs tensors by the exact method worked better than the approximate. The reasons are discussed. The ability of the fitting procedures to recover the correct magnetic parameters of disordered systems was investigated by fittings to synthetic spectra with known hfs tensors. The exact and the approximate methods are concluded to be complementary, one being general, but limited to relatively small systems, the other being a special treatment, suited for S=1/2 systems with several moderately large hfs.

A bone-anchored hearing aid for patients with pure sensorineural hearing impairment: a pilot study.

This pilot study assesses the potential benefits of an optimized bone-anchored hearing aid (BAHA) for patients with a mild to moderate pure sensorineural high frequency hearing impairment. The evaluation was conducted with eight first-time hearing aid users by means of psycho-acoustic sound field measurements and a questionnaire on subjective experience; all of the patients benefited from the BAHA. On average, the eight patients showed improvement in PTA threshold of 3.4 dB and in speech intelligibility in noise of 14%. Seven of the subjects, also fitted with present standard air conduction hearing aids (ACHA) found the ACHA thresholds to be improved more than the BAHA ones. In speech tests, the ACHA was only slightly better; these patients chose between their different hearing aids according to the sound environment. Although the BAHA was preferred for wearing and sound comfort, it cannot be used as the sole aid for patients with pure sensorineural impairment.

Combination of blood-saving methods decreases homologous blood requirements in scoliosis surgery.

A study was conducted in patients undergoing surgery for idiopathic scoliosis, to determine whether combining blood-saving methods would decrease the need for homologous blood. Five groups were compared in a prospective, randomized fashion. In control patients (n = 13), blood loss was replaced by colloids. Preoperative haemodilution (PHD group) was used in ten patients. In the intraoperative autotransfusion (IAT) group (n = 11), washed red cells were returned to the patient. In the PHD+IAT group, both methods were combined (n = 13). In the fifth group, in addition, arterial hypotension was maintained with sodium nitroprusside (the PHD+IAT+HA group, n = 10). The haemoglobin value was kept above 79 g/l. Total blood loss did not differ between groups. The use of homologous blood in the PHD+IAT and PHD+IAT+HA groups was significantly less than in controls. It is concluded that blood-saving measures can be combined with an augmentative effect.

Effects of calprotectin in avridine-induced arthritis.

Plasma levels of calprotectin correlate with disease activity and clinical assessments of arthritis in various rheumatic diseases, and high levels have been demonstrated in the synovial fluid of patients with rheumatoid arthritis. However, the role of calprotectin in rheumatic inflammation is unclear. The purpose of the present study was to investigate potential intra-articular effects of calprotectin. Calprotectin was injected into joints of healthy male Lewis rats and into joints of rats in the latency period before onset of avridine-induced arthritis. In addition, a group of animals had IgG antibodies to rat calprotectin injected into joints before onset of avridine-induced arthritis. Injection of 0.2 or 10 micrograms calprotectin into the ankles of healthy male Lewis rats resulted in histologically minor and reversible inflammatory changes, but without any circulating antibodies to calprotectin. Furthermore, animals with 40 micrograms calprotectin injected into ankles before the expected onset of avridine-induced arthritis had lower scores for cellular infiltration than were seen in control joints. This difference did not quite reach statistical significance in the two-sided test used. However, the induced arthritis increased in joints injected with IgG antibodies to calprotectin. These findings may indicate that increased local concentrations of calprotectin are partially protective against avridine-induced arthritis. In contrast, reduced local concentrations appear to exacerbate the severity of arthritis. Calprotectin may thus be involved in the regulation of inflammatory processes in joints.

Immunohistochemical characterization of synovial cells in arthritic MRL-lpr/lpr mice.

MRL-lpr/lpr (MRL/l) mice spontaneously develop an autoimmune disease associated with arthritic manifestations. We used a recently developed mild demineralization procedure, followed by immunohistochemical staining of frozen sections, to investigate cell patterns in the hindlimbs of MRL/l mice at various stages of arthritic disease. Large numbers of Mac-1 (Mas 034)-positive, macrophage-like cells were seen both within the thickened synovial lining layer and in the deeper layers of the synovial tissue in all stages of arthritis. Ia-expressing cells were scarce in the lining layer, but occurred in moderate numbers in the deeper layers of synovial tissue. Lymphocytes were totally absent in MRL/l joints in all stages of arthritis, as demonstrated by lack of staining with Ly-1, Lyt-2, GK 1,5, and antiimmunoglobulin antibodies. Our findings are discussed and related to other types of experimental arthritis and to rheumatoid arthritis in humans.

A demineralization procedure for immunohistopathological use. EDTA treatment preserves lymphoid cell surface antigens.

An evaluation of the usefulness of EDTA treatment for decalcification of murine bone tissue in order to preserve both morphological details and immunologically intact cell surface antigens has been performed. The ABC immunohistochemical staining technique employing monoclonal antibodies to subsets of T-lymphocytes, B-lymphocytes and to Ia antigens was used on frozen sections. Treatment of mouse hindlegs with EDTA for 14 days resulted in an efficient decalcification and good preservation of morphological details. When lymphoid tissues were handled in the same manner monoclonal antibodies, defining Ly 1, Ly 2, L3T4, MAS 034 and Ia molecules, were shown to retain their reactivity comparable to that of directly frozen tissues. In contrast, formic acid, the commonly used decalcification agent, destroyed most of the antigenic reactivity. We conclude that EDTA treatment of non-fixed, bone-containing tissues provides a suitable demineralization procedure in the immunohistochemical study of, e.g., arthritis and periodontitis.