Frequency Spectra Analysis of Drawbar Pulls Generated by Special Driving Wheels Improving Tractive Performance.

Driving wheel operation is characterized by force interactions with the ground, manifested in the form of vibrations. Signals generated by driving wheels can be analyzed in the frequency spectrum of tractor drawbar pull. The paper presents the analysis of a drawbar pull signal generated by a tractor equipped with two types of special driving wheels and standard tires. Beside the evaluation of special driving wheels' properties according to drawbar power, the frequency spectra of measured signals were analyzed using a fast Fourier transformation. The model spectrum intervals for the standard tires, spike tires, and blade wheels were calculated according to the number of rubber lugs, blades, or spikes and compared with the experimental results. The results showed that the specific frequencies typical for blades and spikes were identified in model spectrum intervals. In the case of standard tires, the spectrum components typical for rubber lugs of the tire tread pattern were not identified. The highest amplitude of the typical frequency component was detected in the case of blades wheels, which showed the highest difference in drawbar power in comparison with the standard tires. Smaller dimensions of spikes resulted in lower amplitude and lower difference in drawbar power in comparison with the standard tires.

Reconstruction of massive post-sternotomy defects with allogeneic bone graft: four-year results and experience using the method.

OBJECTIVES: Deep sternal wound infection poses a serious problem in cardiac surgery, with an up to 40% risk of mortality. Massive loss of sternum bone tissue and adjacent ribs results in major chest wall instability causing respiratory insufficiency and defects of soft tissue healing. Proposals for managing the situation have been published but the complexity of the issue precludes unequivocal resolution. Capitalizing on orthopaedic experience, we used allogeneic bone graft of sternum as a viable option. METHODS: We performed the transplantation of allogeneic bone graft in 10 patients. In 9 cases, an allograft of sternum was used and in 1 case an allograft of calva bone. After the primary cardiac surgery, a massive post-sternotomy defect of the chest wall had developed in all 10 patients. Vacuum wound drainage was applied in the treatment of all patients. To stabilize the transverse, titanium plates were used. Bone allograft was prepared by the official Tissue Centre. Crushed allogeneic spongy bone was applied to reinforce the line of contact of the graft and the edges of residual skeleton. In 9 cases, the soft tissue was closed by direct suture of mobilized pectoral flaps. In 1 case, V-Y transposition of pectoral flap was performed. RESULTS: In 6 cases, healing of the reconstructed chest wall occurred without further complications. In 3 cases, additional re-suture of the soft tissues and skin in the lower pole of the wound was necessary. Excellent chest wall stability along with the adjustment of respiratory insufficiency and good cosmetic effect was achieved in all cases. In 1 case, severe concomitant complications and no healing of the wound resulted in death within 6 months after the reconstruction. Median follow-up of all patients in the series was 14.1 months (1-36 months). In 4 patients, scintigraphy of the chest wall was performed. CONCLUSIONS: Our existing results show that allogeneic bone graft transplantation is a promising and easily applied method in the management of serious tissue loss in sternal dehiscence with favourable functional and cosmetic effects. The relatively small number of patients with such severe healing complications of sternotomy however puts critical limits to a more detailed comparison with other practices and evaluation of long-term results.

Individual myeloma-specific T-cell clones eliminate tumour cells and correlate with clinical outcomes in patients with multiple myeloma.

Despite novel treatment strategies, multiple myeloma (MM) remains an incurable disease with low immunogenicity and multiple immune defects. We developed an ex vivo strategy for inducing myeloma-specific cytotoxic T lymphocytes (CTLs) and demonstrate the possibility of identification and long-term in vivo monitoring of individual myeloma-specific T-cell clones using the most sensitive clonotypic assay that is able to detect low frequencies of T-cell clones (1 clonotypic cell in 10(6) cells). Ten patients with MM were examined for the presence of tumour-reactive T cells using dendritic cells loaded with autologous tumour cells. All patients had detectable myeloma-reactive T cells in vitro. Expanded myeloma-reactive T cells demonstrated specific cytotoxic effects against autologous tumour cells in vitro (median 39.6% at an effector:target ratio of 40:1). The clonality of myeloma-specific T cells was studied with a clonotypic assay, which demonstrated both oligoclonal and monoclonal populations of myeloma-specific T cells. CD8(+) CTLs were the most immunodominant myeloma-specific T-cell clones and clinical responses were closely associated with the in vivo expansion and long-term persistence of individual CD8(+) T-cell clones, usually at very low frequencies (10(-3)-10(-6)). We conclude that the clonotypic assay is the most sensitive tool for immunomonitoring of low-frequency T cells.

Long-term follow-up of Czech children with D+ hemolytic-uremic syndrome.

UNLABELLED: Fifty-seven children (f/m=31/26) who survived diarrhea (D) + hemolytic uremic syndrome (HUS) were evaluated. The examinations were performed 1-27 years (median 7 years) from the onset of the acute disease. Patients aged 2.3-27 years (median 10 years) were allocated to three groups: Recovery (R, complete recovery), Residual renal symptoms (RRS, hematuria and/or proteinuria and/or hypertension with glomerular filtration rate (GFR) >80 ml/min/1.73 m(2), or moderate renal insufficiency with slightly decreased GFR to 60-80 ml/min/1.73 m(2) with or without residual renal symptoms), and Chronic renal insufficiency/failure (CRI/F, dialysis, transplantation - GFR <60 ml/min/ 1.73 m(2)). Results from 18 patients who survived more than 10 years after HUS demonstrated a high prevalence of renal damage. Only 6/18 patients were in group R, 7/18 patients were in group RRS and 5/18 patients were in group CRI/F. An early onset of HUS (36 patients between 0 and 2 years) was associated with a better prognosis when compared with late onset (21 patients aged more than 2 years), P=0.009. Serology typing of Human leukocyte antigens (HLA) classes I and II in 64 patients revealed a significantly higher frequency of DR9 antigen ( P=0.0037) and a lower frequency of DQ1 antigen ( P=0.009) in D+HUS patients compared with healthy Czech blood donors. CONCLUSION: Our study demonstrates a high prevalence of late renal damage in Czech patients surviving after D+HUS. The HLA typing in our group revealed a significantly higher rate of HLA DR9 haplotypes in D+HUS patients.