Studies were carried out to determine if an intraspinal transplant (Trpl) of fetal spinal cord tissue or hind limb exercise (Ex) affected the changes in myosin heavy chain (MyHC) composition or myofiber size that occur following a complete transection (Tx) of the lower thoracic spinal cord of the adult rat. In one group of animals, transplants were made acutely, whereas in a second group, daily cycling exercise was initiated 5 days after injury, with animals in both groups being sacrificed 90 days after injury. The soleus muscle is normally composed of myofibers expressing either type I (90%) or type IIa (10%) MyHC. Following a spinal transection, expression of type I MyHC isoform decreased (18% of myofibers), type IIa MyHC expression increased (65% of myofibers), and the majority of myofibers (80%) expressed type IIx MyHC. Most myofibers coexpressed multiple MyHC isoforms. Compared with Tx only, with Ex or with Trpl, there was a decrease in the number of myofibers expressing type I or IIa isoforms but little change in expression of IIx MyHC. Myofibers expressing the IIb isoform appeared in several transplant recipients but not after exercise. Transection resulted in atrophy of type I myofibers to approximately 50% of normal size, whereas myofibers were significantly larger after exercise (74% of control) and in Trpl recipients (77% of control). Type IIa myofibers also were significantly larger in Trpl recipients compared with the Tx only group. Overall, the mean myofiber size was significantly greater after exercise and in Trpl recipients compared with myofibers in Tx only animals. Thus, although neither strategy shifted the MyHC profile towards the control, both interventions influenced the extent of atrophy observed after spinalization. These data suggest that palliative strategies can be developed to modulate some of the changes in hind limb muscles that occur following a spinal cord injury.

Animals↗

PubMed1999

Inhaled nitric oxide differentiates pulmonary vasospasm from vascular obstruction after surgery for congenital heart disease.

OBJECTIVE: To evaluate whether a trial of inhaled nitric oxide (NO) differentiates reversible pulmonary vasoconstriction from fixed anatomic obstruction to pulmonary blood flow after surgery for congenital heart disease in patients at risk for pulmonary hypertension. DESIGN: Prospective cohort study. SETTING: Tertiary care children's hospital. PATIENTS: 15 neonate and infants with elevated pulmonary artery or right ventricular pressure or with clinical signs suggestive of high pulmonary vascular resistance in the early postoperative period following repair of congenital heart disease. INTERVENTION: 30-min trial of 40 ppm inhaled NO. RESULTS: 5 patients responded to inhaled NO, 2 patients were weaned from extracorporeal support with NO. Four were maintained on continuous inhaled NO for 3 to 5 days. All the responders survived. Ten patients did not respond to NO. An important anatomic obstruction was found with echocardiography or angiography in all 10 patients. Reintervention was performed in 6/10 (4 stent placement, 1 balloon angioplasty of pulmonary arteries and 1 revision of systemic to pulmonary shunt). Six of the nonresponders died. CONCLUSION: A trial of inhaled NO after cardiac surgery in neonates and infants may be useful to differentiate reversible pulmonary vasoconstriction from fixed anatomic obstruction and may provide useful information if temporary support with extracorporeal membrane oxygenation is considered. Failure to respond to inhaled NO should prompt further investigations to rule out a residual obstruction.

Administration, Inhalation↗

PubMed1999

Gender differences in knee cartilage volume as measured by magnetic resonance imaging.

OBJECTIVE: The aim of this study was to analyze sex differences in knee cartilage volume. METHODS: Articulate cartilage volumes were determined by processing images acquired in the sagittal plane using T1-weighted fat saturation magnetic resonance on an independent work station. The knees of 28 subjects (17 male, 11 female) who underwent MRI for clinical indications (pain <3 months) but who had a normal X-ray and structurally normal MRI were examined. RESULTS: Males had significantly larger cartilage volumes than females, with difference in cartilage volume remaining statistically significant after adjusting for age, height, weight and bone volume. The differences for males relative to females were: femoral cartilage volume [4.1 ml 95% CI (2.0, 6.1)]; and patella cartilage volume [1.4 ml (0.2, 2.7)]. Although not statistically significant, the tibial cartilage volume also showed these sex differences. Exploratory analysis indicated an increasing gender difference with increasing age for patellar cartilage volume. CONCLUSION: Men have significantly larger knee cartilage volume than women, independent of body and bone size. The mechanisms for this will need to be determined.

Adult↗

PubMed1998

Treating HIV/AIDS information overload.

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Acquired Immunodeficiency Syndrome↗