EMG Biofeedback as a Tool for Simulating the Effects of Specific Leg Muscle Weakness on a Lifting Task

This study investigated the use of EMG biofeedback to simulate weakened rectus femorii and gastrocnemii muscles during the performance of a lifting task. Eight healthy women performed 15 kg free-style lifts from floor level. Three conditions were tested: unconstrained lifting, lifting with rectus femorii activity volitionally limited bilaterally through EMG biofeedback to less than 45% of maximal EMG activity, and lifting with the gastrocnemii limited to a similar level. Limiting leg muscle activity through biofeedback led to an alteration of lifting strategy, with resulting performance variables (joint angles and torques, angular velocities, center of pressure excursion, and segment coordination) comparing favorably with those from lifting trials performed by six women with moderate leg muscle weaknesses. The data indicate that EMG biofeedback can be used to simulate the effects of leg muscle weakness during these lifts, providing a new tool to study the biomechanics of muscle weakness.     

Computed radiography versus screen-film radiography: detection of pulmonary edema in a rabbit model that simulates neonatal pulmonary infiltrates.

PURPOSE: To determine if computed radiography is equivalent to screen-film radiography in depicting pulmonary edema and to determine if radiation exposure can be reduced with computed radiography while maintaining equivalent diagnostic accuracy for pulmonary edema. MATERIALS AND METHODS: Oleic acid was intravenously injected into three rabbits at each of four doses: 0, 0.02, 0.04, and 0.06 mL/kg. Two hours later, chest computed radiographs and screen-film radiographs were obtained at 60 kVp and 1.1 mAs. Additional computed radiographs were obtained after reducing milliampere seconds or by reducing milliampere seconds and increasing the kilovolt peak, which reduced bone marrow exposure by up to 20%. The presence of pulmonary opacities, "truth," was established by the wet-dry weight ratio and by chest computed tomography (CT). The radiographs were masked and randomized. Four observers rated the images for the presence of parenchymal opacities with a dichotomous score and judged the quality of the radiographs on a scale from 1 (worst) to 6 (best). Cochran Q tests and McNemar tests were used to analyze the differences in paired comparisons. Image quality was evaluated with logistic regression analysis. RESULTS: There was no significant difference between truth and observer ability to detect opacity for either modality or for any exposure (P > .05). There was no significant difference between computed radiography and screen-film radiography for image quality (P > .05). CONCLUSION: Computed radiography is equivalent to screen-film radiography in the detection of pulmonary edema. Radiation exposure reduction of 20% can be achieved without affecting pulmonary edema detection or image quality.     

The application of Ion chromatographic method for bioavailability and stability test of iron preparations

Postabsorptive serum iron level was determined after oral administration of the compounds to human. In serum and whole blood, Fe3+ was measured by ion chromatography (IC) using a pyridine-2,6-dicarboxylic acid (PDCA) as an eluent. The serum sample solutions were pretreated with I N HCI and 50% TCA. The whole blood sample solutions were treated with 3 N HCI for 30 min at 125 degrees C. The limit of detection (LOD) of the IC technique is 0.2 microM for Fe2- and 0.1 microM for Fe3+. The area under concentration (AUC) can be obtained by the above analytical condition. In addition, to compare the stability of Fe2+ to that of Fe3+ in pharmaceutical preparations, accelerated stability test was carried out. After storing the samples under 40 degrees C, 75%RH in light-resistant container for various time intervals, the contents of iron of different valencies were determined separately by the IC technique and the change and/or the interchange of among those iron species in preparations was investigated. Iron raw materials are stable, but Fe2+ in Fe3+ source materials was slightly converted to Fe3+ by oxidation. Fe2+ in Fe3+ source raw materials and Fe3+ in Fe2+ raw materials are determined as impurities. Therefore, IC technique is found to be an appropriate method for comparative evaluation of dissimilar bioavailability of Fe2+ and Fe3+, stability of Fe2+ and Fe3+ raw materials and preparations.     

Enhancing preventive and primary care for children with chronic or disabling conditions served in health maintenance organizations

Health maintenance organizations serve an estimated 20 percent of the child population, approximately 12 million children, many of whom have chronic conditions or disabling conditions. These children consume a disproportionate share of health resources and represent an important challenge in terms of care management. As HMOs increasingly enroll children with private insurance and Medicaid who have various physical, developmental, behavioral, and emotional disorders, they must find new and innovative ways to provide their care. Almost one third of children are affected by chronic conditions, and a smaller percentage (6 percent) suffer from chronic disabling conditions. Seven design elements for enhancing preventive and primary care for children with chronic conditions are presented in this article with illustrative examples from HMOs and state Medicaid programs.     

Cerebral blood flow velocity after mannitol infusion in children

Purpose

There is conflicting evidence as to whether the effect of mannitol on brain bulk arises from haemodynamic, rheologic, or osmotic mechanisms. If mannitol alters cerebral haemodynamics by inducing vasoconstriction, this change should be reflected in cerebral blood flow velocity (CBFV) in the middle cerebral artery (MCA). The purpose of this study was to evaluate the effect of mannitol on CBFV in children.

Methods

Children scheduled for intracranial surgery were enrolled. After a loading dose of 10 μg · kg^?1 of fentanyl, general anaesthesia was maintained with fentanyl (3 μg · kg^?1 · hr^?1), 66% nitrous oxide, and isoflurane (0.2–0.5% inspired). Mean and systolic CBFV (Vm and Vs) and pulsatility index (PI) were recorded with a transcranial Doppler (TCD) directed at the M1 segment of the MCA. Mannitol was administered, 1 gm · kg^?1 iv over 15 min. The osmolality (Osm), haematocrit (Hct), mean arterial pressure (MAP), heart rate (HR), and TCD variables were recorded before and 15, 30, 45, and 60 min after the mannitol infusion.

Results

Mannitol infusion resulted in an increase in Osm and decrease in Hct (P < 0.05). Heart rate, MAP and arterial carbon dioxide tensions did not change (P > 0.05) during the measuring period. The Vm did not vary from baseline. The Vs and P1 both increased briefly (P < 0.01 at 15 min and P < 0.05 at 30 min) after the mannitol, suggesting an increase in resistance distal to the MCA.

Conclusion

The time course of CBFV changes produced by mannitol corresponds with previous animal data concerning cerebrovascular tone. Our results suggest that mannitol briefly increases cerebrovascular resistance and thereby diminishes cerebral blood volume.     

Definition of inseparably fused ventricular myocardium in thoracopagus: Fetal echocardiographic utility and pathologic refinement

Summary Correlative echocardiographic and pathological findings in a thoracopagus with conjoined hearts are reported. One twin had tricuspid atresia with discordant atrioventricular connections and concordant ventriculoarterial connections. The morphologic right ventricle was hypoplastic and there was a large muscular ventricular septal defect. The other twin had hypoplasia of the mitral valve anulus and left ventricle with double-outlet right ventricle and pulmonary valve atresia. The tricuspid valve was severely insufficient in part because of a large orifice and redundant, elongated leaflets with abnormal chordal attachments. The left ventricles of these two twins shared a perforated common free wall with at least two large defects allowing mixing of the circulations at that level. Not all anatomic details were established conclusively by fetal echocardiography; however, sufficient diagnostic information was obtained to support a decision not to aggressively resuscitate these twins after elective cesarean delivery at 31 weeks' gestation.     

Flexible fiberoptic sigmoidoscopy—The monroe clinic experience

Analysis of 5000 consecutive flexible fiberoptic sigmoidoscopies form the basis of this report. It is concluded that this method of examination of the distal large bowel is not only safe and comfortable for the patient but is a more appropriate examination than the rigid proctosigmoidoscopy because of the significant increase in pathologic material found. This examination has proven practical and acceptable in a multispecialty clinic setting and has completely replaced rigid proctosigmoidoscopy. Flexible sigmoidoscopy is now the standard "routine" examination of the rectum and distal colon. The rationale for this conclusion is presented in this timely report.