High prevalence of vitamin D insufficiency in healthy elderly people living at home in Argentina.

OBJECTIVE: To evaluate the nutritional status of vitamin D in urban populations of healthy elderly people living at home, in different regions of Argentina. DESIGN: Cross-sectional study. SUBJECTS: In total, 386 ambulatory subjects over 65 y of age from seven cities (between latitude 26 degrees S and 55 degrees S) were asked to participate between the end of winter and the beginning of spring. Of these, 369 accepted, 30 were excluded because of medical history or abnormal biochemical determinations. Finally, 339 subjects (226 women and 113 men) (X+/-s.d.) (71.3+/- 5.2 y) were included. RESULTS: Serum 25OHD levels were lowest in the South (latitude range: 41 degrees S-55 degrees S): 14.2+/-5.6 ng/ml (P<0.0001vs North and Mid regions); highest in the North (26 degrees S-27 degrees S): 20.7+/-7.4 ng/ml (P<0.03 vs Mid, P<0.0001vs South); and intermediate in the Mid region (33 degrees S-34 degrees S) 17.9+/-8.2 ng/ml. Serum mid-molecule PTH (mmPTH) and 25OHD were inversely related: (r=-0.24, P<0.001). A cutoff level of 25OHD at which serum mmPTH levels began to increase was established at 27 ng/ml. A high prevalence (87-52%) of subjects with 25OHD levels in the deficiency-insufficiency range (25OHD levels <20 ng/ml) was detected. CONCLUSION: This study shows that vitamin D deficiency/insufficiency in the elderly is a worldwide problem. Correction of this deficit would have a positive impact on bone health of elderly people.

Objective quantification of spastic hypertonia: correlation with clinical findings.

To develop a reliable and objective technique for quantifying spastic hypertonia, ten chronically hemiplegic patients with varying degrees of spasticity were studied on three occasions during several weeks. The modified Ashworth scale, a clinical assessment of extremity tone, was performed before and after each of the following objective tests: (1) torque and EMG measurements during ramp and hold angular displacement about the elbow, (2) pendulum test of the lower extremity, and (3) H/M ratio studies of upper and lower extremities. Subject motor function was also quantified using the Fugl-Meyer motor assessment scale. A regression analysis was performed to determine how successfully each of the objective measures correlated with the clinical yardstick, the modified Ashworth scale. A similar correlation between the objective measures and the Fugl-Meyer motor assessment scale was performed. Temporal reproducibility of a test for a given subject was evaluated by performing an ANOVA of repeated measures for each test over the three study sessions in a given subject. We conclude that (1) both the ramp and hold threshold measurements and pendulum test offer acceptable objective measures of spastic hypertonia since they correlate closely with clinical perception, (2) the Fugl-Meyer motor assessment scale also correlates closely with the severity of spastic tone, and (3) objective measures of spastic hypertonia are often surprisingly reproducible when repeatedly applied to a selected group of chronic hemiplegic patients with long-standing spasticity.

Strategies for muscle activation during isometric torque generation at the human elbow.

1. We studied the patterns of electromyographic (EMG) activity in elbow muscles of 14 normal human subjects. The activity of five muscles that act in flexion-extension and forearm supination-pronation was simultaneously recorded during isometric voluntary torque generation, in which torques generated in a plane orthogonal to the long axis of the forearm were voluntarily coupled with torques generated about the long axis of the forearm (i.e., supination-pronation). 2. When forearm supination torques were superimposed on a background of elbow flexion torque, biceps brachii activity increased substantially, as expected; however, brachioradialis and brachialis EMG levels decreased modestly, a less predictable outcome. The pronator teres was also active during pure flexion and flexion coupled with mild supination (even though no pronation torque was required). This was presumably to offset inappropriate torque contributions of other muscles, such as the biceps brachii. 3. When forearm supination torque was superimposed on elbow extension torque, again the biceps brachii was strongly active. The pronator teres also became mildly active during extension with added pronation torque. These changes occurred despite the fact that both the pronator and biceps muscles induce elbow flexion. 4. In these same elbow extension tasks, triceps brachii activity was also modulated with both pronation or supination loads. It was most active during either supination or pronation loads, again despite the fact that it has no mechanical role in producing forearm supination-pronation torque. 5. Recordings of EMG activity during changes in forearm supination-pronation angle demonstrated that activation of the biceps brachii followed classic length-tension predictions, in that less EMG activity was required to achieve a given supination torque when the forearm was pronated (where biceps brachii is relatively longer). On the other hand, EMG activity of the pronator teres did not decrease when the pronator was lengthened. Triceps EMG was also more active when the forearm was supinated, despite its having no direct functional role in this movement. 6. Plots relating EMG activity in biceps brachii, brachialis, and brachioradialis at three different forearm positions revealed that there was a consistent positive near-linear relationship between brachialis and brachioradialis and that biceps brachii is often most active when brachioradialis and brachialis are least active. 7. We argue that, for the human elbow joint at least, fixed muscle synergies are rather uncommon and that relationships between muscle activities are situation dependent.(ABSTRACT TRUNCATED AT 400 WORDS)