Antigenic and virulence properties of Pasteurella haemolytica leukotoxin mutants.

Antigenic properties of two mutants of Pasteurella haemolytica, strains 59B0071 and 59B0072, that do not produce detectable leukotoxin were investigated. Western blot (immunoblot) analysis with a number of polyclonal sera from animals recovering from pasteurellosis revealed that both mutants secreted a variety of antigens that were also present in cultures of several wild-type strains. These antigens ranged from about 100 to 15 kDa. Mutant strain 59B0071 was found to be totally deficient in leukotoxin, as judged not only by Western blotting but also by cytotoxicity assays with bovine lymphoma (BL-3) cells or bovine polymorphonuclear cells as targets. The mutant strain 59B0071 had normal levels of a secreted sialylglycoprotease, however. When strains were tested for virulence in goat and cattle challenge experiments, a reduction in mortality and lung lesions was observed with the mutant 59B0071 in comparison with results obtained with wild-type strains. These results are consistent with an important role for leukotoxin in P. haemolytica virulence and suggest that leukotoxin-negative mutants may be useful tools in the investigation of other virulence properties involved in P. haemolytica infections.     

Long-term results of DeVega tricuspid annuloplasty

DeVega tricuspid annuloplasty was performed in 74 patients undergoing mitral or mitral and aortic valve replacement between January, 1972, and December, 1985. Sixty-two hospital survivors have been followed up for a mean of 85.3 +/- 6.6 months. Actuarial survival at 14 years was 71.5 +/- 8.2%. None of the late deaths was related to the tricuspid annuloplasty. Three patients required tricuspid valve replacement for recurrence of tricuspid regurgitation (0.68% per annum). Eleven asymptomatic patients studied hemodynamically at a mean period of 53 months after the operation showed maintenance of the hemodynamic improvement. We recommend DeVega annuloplasty as the method of choice for moderate to severe tricuspid regurgitation in the absence of an organically diseased or deformed valve.     

Effects of restricted feeding cycle on the locomotor activity rhythm in the mouse Mus booduga

The effect of restricted feeding (RF) cycles on the circadian locomotor activity rhythm was studied in the nocturnal field mouse Mus booduga. Mice were presented with a 2-h meal schedule every 24 h in continuous darkness (DD), in continuous light (LL), and in a light-dark (LD) cycle. Additionally, in DD, two groups of mice were subjected to RF cycles of periodicities 22 (T22) and 26 h (T26), respectively, in order to assess the limits of entrainment. The T22 and T26 RF cycles failed to produce any entrainment of the locomotor activity rhythm, whereas some of the animals that had a free-running period (tau) close to 24 h showed stable entrainment or "relative coordination" to daily (T24) RF cycle. In LD, the locomotor activity rhythm phase advanced under the influence of the daily RF cycle when the food presentation preceded the light to dark (L to D) transition by 5-6 h. However, when the timing of food presented in the RF cycle coincided with the L to D transition, locomotor activity rhythm dissociated into two components. Some of the mice whose locomotor activity rhythm disappeared in LL showed prominent meal-AA. These results suggest that RF modifies the expression of the light-entrainable pacemaker (LEP) directly and also that in the absence of the expression of the LEP, RF can induce meal-AA.     

The relevance of donor T cell-directed immunoglobulin G in historic sera in the age of flow cytometry

BACKGROUND: Renal transplant recipients with a positive historic cross-match due to donor T cell-directed IgG antibodies are considered to have decreased graft survival, even if their current serum is negative prior to transplantation. With the use of flow cytometric cross-match for testing current sera, false-negative results could be eliminated and the outcome of transplantation in this group of patients could be improved, assuming that immunological memory is effectively controlled with immunosuppression. METHODS: We reviewed our records to identify those patients who underwent cadaveric renal transplant, with a historic IgG positive cytotoxic T cell cross-match and a current negative flow cytometric T cell cross-match. RESULTS: Eighteen patients underwent cadaveric renal transplant in the face of a historic IgG positive T cell cross-match and a current negative flow cytometric T cell cross-match. In 14 patients treated with cyclosporine-based immunosuppression the 1-, 2-, and 3-year cumulative graft survival rates were 57, 50, and 43%, respectively. Ten of the 14 patients (71%) ultimately lost their grafts. CONCLUSIONS: Even with negative flow cytometric cross-match in current serum, a positive historic conventional cross-match suggests a high risk of graft failure.     

Eco-friendly microbial route to synthesize cobalt nanoparticles using Bacillus thuringiensis against malaria and dengue vectors

The developments of resistance and persistence to chemical insecticides and concerns about the non-target effects have prompted the development of eco-friendly mosquito control agents. The aim of this study was to investigate the larvicidal activities of synthesized cobalt nanoparticles (Co NPs) using bio control agent, Bacillus thuringiensis against malaria vector, Anopheles subpictus and dengue vector, Aedes aegypti (Diptera: Culicidae). The synthesized Co NPs were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR), Field-emission scanning electron microscopy (FESEM) with energy dispersive X-ray spectroscopy, and Transmission electron microscopy (TEM). XRD analysis showed three distinct diffraction peaks at 27.03°, 31.00°, and 45.58° indexed to the planes 102, 122, and 024, respectively on the face-centered cubic cobalt acetate with an average size of 85.3 nm. FTIR spectra implicated role of the peak at 3,436 cm^?1 for O–H hydroxyl group, 2924 cm^?1 for methylene C–H stretch in the formation of Co NPs. FESEM analysis showed the topological and morphological appearance of NPs which were found to be spherical and oval in shape. TEM analysis showed polydispersed and clustered NPs with an average size of 84.81 nm. The maximum larvicidal mortality was observed in the cobalt acetate solution, B. thuringiensis formulation, and synthesized Co NPs against fourth instar larvae of A. subpictus and A. aegypti with LC₅₀ values of 29.16, 8.12, 3.59 mg/L; 34.61, 6.94, and 2.87 mg/L; r ² values of 0.986, 0.933, 0.942; 0.962, 0.957, and 0.922, respectively.