Biomechanical analysis of wheelchair athletes with paraplegia during cross-training exercises

CONTEXT

Extreme conditioning programs (ECPs), such as CrossFit^®, are a relatively new method of fitness with rapid growth in individuals with paraplegia. However, it is unknown if wheelchair users are at an additional risk of musculoskeletal injury during these exercises. Biomechanical characterization is necessary to determine the safety and efficacy of ECPs as an exercise modality for wheelchair users with paraplegia.

OBJECTIVE

To characterize the three-dimensional (3-D) thorax and upper extremity joint kinematics of paraplegic wheelchair athletes during exercises commonly prescribed as part of ECPs.

DESIGN

Observational study.

PARTICIPANTS

Three male wheelchair athletes, average age of 37.1 ± 4.6 years, with spinal cord injury levels of T8, L2, and T10, with varying exercise experience.

METHODS

3-D movement was acquired using motion capture during the performance of four exercises: battle ropes, sled pull, overhead press, and sledgehammer swing. A custom upper extremity inverse kinematics model was applied to compute 3-D joint angles.

OUTCOME MEASURES

3-D peak thorax, glenohumeral, elbow, and wrist joint angles and ranges of motion (ROM), Visual Analog Scale (VAS), and Borg Scale of Perceived Exertion.

RESULTS

Large joint motions were required for the exercises, at times demanding extreme shoulder and/or wrist flexion and extension, abduction, and external rotation, which are concerning for injury risk in wheelchair users. Participants, however, were able to perform the exercises pain free.

CONCLUSION

These quantitative findings highlight that wheelchair athletes may be exposed to potentially injurious positions during common ECP exercises. These findings provide insight that may lead to improved clinical guidelines for prescription and training of exercise regimens, particularly involving ECPs, for wheelchair users.

[Septic shock with purpura fulminans after a dog bite]

HISTORY AND CLINICAL FINDINGS

A 61-year-old man presented with a four-day history of back pain and nonspecific abdominal pain. His condition had significantly worsened since the day before admission with generalized weakness and dyspnea. His temperature was 39.1 C, he had tachycardia and was tachypneic. Peripheral cyanosis was noted. The abdomen was soft with mild epigastric tenderness. A diffuse skin rash developed with increasing petechial bleeding and central necrosis. It was revealed that he had been bitten by a dog several weeks before admission.

INVESTIGATIONS

Laboratory data indicated an acute inflammatory process with a marked increase in white blood cells and C-reactive protein. An elevated procalcitonin level suggested a systemic bacterial infection. Chest X-ray and abdominal CT scan were unremarkable. Echocardiography revealed a globally hypokinetic heart with no evidence of valvular vegetations. One set of blood cultures grew micro-aerophilic, Gram-negative rods. Gene sequencing identified the slow growing, fastidious bacillus as CAPNOCYTOPHAGA CANIMORSUS.

TREATMENT AND COURSE

The patient was admitted to the intensive care unit and initially treated with intravenous piperacillin/tazobactam and hydrocortisone for septic shock. Transfusions of platelets and blood products were given because of disseminated intravascular coagulation. The patient developed multi-organ failure requiring ventilation and hemodialysis; he died four days after admission.

CONCLUSIONS

As a rare cause of septicemia, especially in immunocompromised patients, Capnocytophaga canimorsus infection should be considered after an animal bite. Given the slow growth of this bacterium in culture, Gram-staining of a peripheral blood smear may provide an early diagnosis and avoid delay before appropriate antibiotic therapy, which may favorably influence the potentially fatal course, is started.

Isolation of catalase-negative Listeria monocytogenes strains from listeriosis patients and their rapid identification by anti-p60 antibodies and/or PCR

Two catalase-negative Listeria monocytogenes serovar 1/2b strains were isolated from listeriosis patients in 1995 in Germany. The infections appeared in individuals from different cities at different seasons and were caused by L. monocytogenes strains of different clonal types. In particular, the catalase reaction of one strain isolated from blood was consistently negative, whereas this reaction was only reversibly blocked when the strain was freshly isolated from ascitic fluid. After subculturing, the catalase-positive reaction was restored. Initially, identification of these isolates was difficult to achieve not only because of the lack of a catalase reaction, which generally distinguishes L. monocytogenes from other morphologically similar pathogenic gram-positive bacteria, but also because other routinely used biochemical tests such as CAMP and the commercial API test gave unclear results. However, rapid and unequivocal identification of these strains was possible by analyzing secretions of the p60 protein in culture supernatants by enzyme-linked immunosorbent assay or Western blot (immunoblot) analysis with our recently developed Listeria- and L. monocytogenes-specific anti-p60 antibodies. Additionally, the identifications were confirmed by Listeria- and L. monocytogenes-specific PCR analyses with primers derived from the iap, hly, and prfA genes. Immunoanalyses also allowed for the differentiation of these two strains, whereas no differentiation was possible by PCR when the internal, variable repetitive iap gene portion was analyzed. However, size variations of the PCR products comprising these gene portions which were obtained from a number of L. monocytogenes strains belonging to the same serotypes indicated that this type of PCR is not only useful for specific identifications but may be used in parallel as an additional marker for epidemiological studies. In conclusion, the data suggest that catalase production should not be taken as a strict criterion for the identification of listeriae. Furthermore, at least the infection caused by the stably catalase-negative strain supports the notion that catalase does not seem to be necessary for the intracellular growth of L. monocytogenes.

Adherence to bovine neutrophils and suppression of neutrophil chemiluminescence by Mycoplasma bovis

The adherence of viable and heat-treated Mycoplasma bovis to bovine peripheral blood neutrophils was studied by specific immunofluorescence staining and flow cytometry. Viable and heat-treated M. bovis cells, adhered to bovine neutrophils in dose-dependent fashion within a 30 min incubation. Fluorescence quenching using crystal violet indicated that unopsonized M. bovis cells remained on the surface of bovine neutrophils without experiencing significant ingestion. The effect of M. bovis adherence on neutrophil microbicidal function was examined by measuring luminol enhanced chemiluminescence (CL). Adherent M. bovis cells did not elicit a bovine neutrophil CL response over a 75 min incubation period. M. bovis inhibited the capacity of bovine neutrophils to mount a CL response. Inhibition occurred whether viable or heat-treated M. bovis cells were used and it occurred when neutrophils were stimulated with opsonized zymosan (OZ) or phorbol myristate acetate (PMA). Inhibition of the PMA stimulated neutrophil CL response required cytadherence by M. bovis cells. These findings suggest that activation of the bovine neutrophil respiratory burst was inhibited at or distal in the pathway to the activation of protein kinase C (PKC), the site of PMA stimulation, and that it was mediated by a direct interaction between the adhering M. bovis cells and the bovine neutrophil membrane.