The loss of sensory perception secondary to diabetic distal symmetrical sensory neuropathy has a markedly detrimental effect on postural stability. The deficit is greatest when visual or vestibular cues are absent or degraded. Patients with neuropathy need to be informed of the postural consequences of this condition to limit the potential morbidity caused by falls.
In the present study we used regression analyses to evaluate the effects of stearic acid (18:0) on total cholesterol (TC), low-density-lipoprotein-cholesterol (LDL-C), and high-density-lipoprotein-cholesterol (HDL-C) concentrations (mmol/L). Using data from 18 articles, we developed the following predictive equations (monounsaturated fatty acids, MUFAs; polyunsaturated fatty acids, PUFAs): delta TC = 0.0522 delta 12:0-16:0 - 0.0008 delta 18:0 - 0.0124 delta MUFA - 0.0248 delta PUFA; delta LDL-C = 0.0378 delta 12:0-16:0 + 0.0018 delta 18:0 - 0.0178 delta MUFA - 0.0248 delta PUFA; delta HDL-C = 0.0160 delta 12:0-16:0 - 0.0016 delta 18:0 + 0.0101 delta MUFA + 0.0062 delta PUFA. Our analyses revealed that unlike the other long-chain saturated fatty acids (SFAs), stearic acid had no effect on TC and lipoprotein cholesterol concentrations in men and women. MUFAs elicited an independent hypocholesterolemic effect that we believe is due to the small amount of 12:0-16:0 in the experimental diets evaluated. The observation that stearic acid has unique effects on TC, LDL-C, and HDL-C provides additional compelling evidence that it be distinguished from the other major SFAs in blood cholesterol predictive equations.
Peripheral neuropathy secondary to diabetes mellitus is believed to cause postural instability and uncoordinated gait, although this is not well documented. Two groups of patients from the Pittsburgh Epidemiology of Diabetes Complications Study, matched for age and duration of Type 1 diabetes, but with significantly different vibratory sensation thresholds as determined by Vibratron II testing, were therefore surveyed. The mean ages were 32.9 and 31.9 years and durations of diabetes were 22.0 and 18.8 years for the neuropathic and control groups, respectively. Patients provided details of fall injuries, and perception of safety during standing and walking. Multiple linear and logistic regression models were used to account for potentially associated variables such as gender, retinopathy, and duration of diabetes. The neuropathic group had adjusted odds ratios for reported injuries during gait of 15.0 relative to the control group (95% confidence intervals 1.04-216.59). The neuropathic group also reported significantly lower scores (less safe, p = 0.004) than the control group on perceived safety in unusual conditions. It is concluded that peripheral neuropathy has an effect on gait and posture which is clinically significant and that this effect merits further biomechanical study in neuropathic patients.
Older men and women respond to local and reflex-mediated heat stress with an attenuated increase in cutaneous vascular conductance (CVC). This study was performed to test the hypothesis that an augmented or sustained noradrenergic vasoconstriction (VC) may play a role in this age-related difference. Fifteen young (22 +/- 1 yr) and 15 older (66 +/- 1 yr) men exercised at 50% peak oxygen uptake in a 36 degrees C environment. Skin perfusion was monitored at two sites on the right forearm by laser-Doppler flowmetry: one site pretreated with bretylium tosylate (BT) to block the local release of norepinephrine and thus VC and an adjacent control site. Blockade of reflex VC was verified during whole body cooling using a water-perfused suit. CVC (perfusion divided by mean arterial pressure) at each site was reported as a percentage of the maximal CVC (%CVCmax) induced at the end of each experiment by prolonged local heating at 42 degrees C. Neither age nor BT affected the %CVCmax (75-86%) attained at high core temperatures. During the early rise phase of CVC, the %CVCmax-change in esophageal temperature (delta T(es)) curve was shifted to the right in the older men (effective delta T(es) associated with 50% CVC response for young, 0.22 +/- 0.04 and 0.39 +/- 0.04 degrees C and for older, 0.73 +/- 0.04 and 0.85 +/- 0.04 degrees C at control and BT sites, respectively). BT had no interactive effect on this age difference, suggesting a lack of involvement of the VC system in the attenuated CVC response of individuals over the age of 60 yr. Additionally, increases in skin vascular conductance were quantitatively compared by measuring increases in total forearm vascular conductance (FVC, restricted to the forearm skin under these conditions). After the initial approximately 0.2 degrees C increase in T(es), FVC was 40-50% lower in the older men (P < 0.01) for the remainder of the exercise. Decreased active vasodilator sensitivity to increasing core temperature, coupled with structural limitations to vasodilation, appears to limit the cutaneous vascular response to exertional heat stress in older subjects.
Ten women with iron-deficiency anemia, 8 with depleted iron stores (nonanemic), and 12 control women, all of similar body fatness, were exposed to a 28 degrees C water bath to test the hypothesis that iron-deficiency anemia impairs thermoregulatory performance. The anemic women had lower rectal temperatures than did control women (36.0 +/- 0.2 vs 36.2 +/- 0.1 degree C, respectively, P = 0.001) and a lower rate of oxygen consumption (5.28 +/- 0.26 vs 5.99 +/- 0.29 mL.min-1.kg body wt-1, respectively, P = 0.04) at 100 min of cold exposure. Plasma thyroxine and triiodothyronine concentrations were significantly (P less than 0.002) lower in anemic than in control women at baseline and during cold exposure. Responses of iron-depleted subjects were similar to those of control subjects. Iron supplementation corrected the anemia, significantly (P = 0.03) improved rectal temperature at 100 min, and partially normalized plasma thyroid hormone concentrations. Plasma catecholamines were unaffected by iron status. This experiment demonstrates a functional consequence of iron-deficiency anemia in the balance of heat production and loss and suggests that thyroid-hormone metabolism may be responsible.
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