Effects of weight loss on regional fat distribution and insulin sensitivity in obesity.
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Weight loss (WL) decreases regional depots of adipose tissue and improves insulin sensitivity, two parameters that correlate before WL. To examine the potential relation of WL-induced change in regional adiposity to improvement in insulin sensitivity, 32 obese sedentary women and men completed a 4-month WL program and had repeat determinations of body composition (dual-energy X-ray absorptiometry and computed tomography) and insulin sensitivity (euglycemic insulin infusion). There were 15 lean men and women who served as control subjects. VO2max was unaltered with WL (39.2 +/- 0.8 vs. 39.8 +/- 1.1 ml x fat-free mass [FFM](-1) x min(-1)). The WL intervention achieved significant decreases in weight (100.2 +/- 2.6 to 85.5 +/- 2.1 kg), BMI (34.3 +/- 0.6 to 29.3 +/- 0.6 kg/m2), total fat mass (FM) (36.9 +/- 1.5 to 26.1 +/- 1.3 kg), percent body fat (37.7 +/- 1.3 to 31.0 +/- 1.5%), and FFM (59.2 +/- 2.3 to 55.8 +/- 2.0 kg). Abdominal subcutaneous and visceral adipose tissue (SAT and VAT) were reduced (494 +/- 19 to 357 +/- 18 cm2 and 157 +/- 12 to 96 +/- 7 cm2, respectively). Cross-sectional area of low-density muscle (LDM) at the mid-thigh decreased from 67 +/- 5 to 55 +/- 4 cm2 after WL. Insulin sensitivity improved from 5.9 +/- 0.4 to 7.3 +/- 0.5 mg x FFM(-1) x min(-1) with WL. Rates of insulin-stimulated nonoxidative glucose disposal accounted for the majority of this improvement (3.00 +/- 0.3 to 4.3 +/- 0.4 mg x FFM(-1) x min(-1)). Serum leptin, triglycerides, cholesterol, and insulin all decreased after WL (P < 0.01). After WL, insulin sensitivity continued to correlate with generalized and regional adiposity but, with the exception of the percent decrease in VAT, the magnitude of improvement in insulin sensitivity was not predicted by the various changes in body composition. These interventional weight loss data underscore the potential importance of visceral adiposity in relation to insulin resistance and otherwise suggest that above a certain threshold of weight loss, improvement in insulin sensitivity does not bear a linear relationship to the magnitude of weight loss. (+info)
Clinical and radiological aspects of idiopathic diabetic muscle infarction. Rational approach to diagnosis and treatment.
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The systemic effects of diabetes mellitus are well recognised. The heart, kidney, central and peripheral nervous systems, and the distal parts of the limbs are often the site of end-organ damage resulting from ischaemia. Infarction of large muscle groups in the limb, not associated with gangrene, is uncommon. There have been few reported cases other than radiological descriptions of diabetic muscle infarcts. While previous reports have illustrated some of the clinical and radiological characteristics of this condition, the paucity of published cases makes it difficult to determine the most appropriate methods of diagnosis and treatment. During a five-year period we treated 14 patients with diabetes mellitus, aged from 32 to 59 years, who were referred to a musculoskeletal oncology service for suspected soft-tissue sarcoma, but were subsequently found to have a diabetic muscle infarct. Closed needle biopsy was performed in 13 without complications. In 12 patients, the symptoms resolved without surgical treatment. (+info)
Dynamic strength of the quadriceps muscle and sports activity.
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The study objectives were to examine the dynamic strength of the quadriceps muscle in athletes, and investigate its association with participation in sport. The study comprised 168 active competitive non-pregnant athletes, aged 14-24 years. The dynamic strength of their quadriceps muscle was measured, and they answered a questionnaire about sports activity and occupation. The dynamic strength of the quadriceps muscle was significantly higher in men than in women, and was positively associated with body weight, years of jogging, years of soccer, and weekly hours of basketball. In conclusion, the dynamic strength of the quadriceps muscle seems to be associated with sports activity. The results suggest sport specific adaptation, which may reflect high levels of running and jumping activity. (+info)
Cortical control of spinal pathways mediating group II excitation to human thigh motoneurones.
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1. The possibility was investigated that cortical excitation to human thigh motoneurones is relayed via lumbar premotoneurones. 2. Test responses were evoked by transcranial magnetic stimulation (TMS) in voluntarily contracting quadriceps (Q) and semitendinosus (ST) muscles: either a motor evoked potential (MEP) in surface recordings or a peak of cortical excitation in the post-stimulus time histogram (PSTH) of single motor units was used. These test responses were conditioned by stimuli to the common peroneal (CP) or gastrocnemius medialis (GM) nerves. 3. CP stimulation evoked a large biphasic facilitation of the Q MEP, with early, short-lasting, low-threshold (0.6-0.8 x motor threshold (MT)) and late, longer lasting and higher threshold (1.2-1.5 x MT) peaks separated by a period of depression. GM nerve stimulation evoked a similar early depression and late facilitation in the ST MEP. 4. CP-induced effects in the Q H reflex were different (smaller late facilitation not preceded by any depression), suggesting that CP and cortical volleys interact at a premotoneuronal level to modify the Q MEP. 5. Peaks of cortical excitation evoked by TMS in single motor unit PSTHs were modulated by the conditioning volley like the MEPs with, in Q motor units, early and late CP-induced facilitations separated by a depression, and in ST motor units a late GM-induced facilitation. Facilitations on combined stimulation (i) were greater than the sum of effects by separate stimuli and (ii) never affected the initial part of the cortical peak. 6. It is concluded that the features of the reported facilitatory interactions between cortical and peripheral volleys are consistent with interactions in a population of lumbar excitatory premotoneurones co-activated by group I and group II afferents. The potency of the effects suggests that a significant part of the cortical excitation to motoneurones of thigh muscles is relayed via these interneurones. 7. It is argued that the early depression in ST motoneurones and the separation of the two peaks of facilitation in Q motoneurones reflect a cortical facilitation of spinal inhibitory interneurones projecting on excitatory premotoneurones. (+info)
Recruitment order among motoneurons from different motor nuclei.
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Recruitment order among motoneurons from different motor nuclei. The principles by which motoneurons (MNs) innervating different multiple muscles are organized into activity are not known. Here we test the hypothesis that coactivated MNs belonging to different muscles in the decerebrate cat are recruited in accordance with the size principle, i.e., that MNs with slow conduction velocity (CV) are recruited before MNs with higher CV. We studied MN recruitment in two muscle pairs, the lateral gastrocnemius (LG) and medial gastrocnemius (MG) muscles, and the MG and posterior biceps femoris (PBF) muscles because these pairs are coactivated reliably in stretch and cutaneous reflexes, respectively. For 29/34 MG-LG pairs of MNs, the MN with lower CV was recruited first either in all trials (548/548 trials for 22 pairs) or in most trials (225/246 trials for 7 pairs), whether the MG or the LG MN in a pair was recruited first. Intertrial variability in the force thresholds of MG and LG MNs recruited by stretch was relatively low (coefficient of variation = 18% on average). Finally, punctate stimulation of the skin over the heel recruited 4/4 pairs of MG-LG MNs in order by CV. By all of these measures, recruitment order is as consistent among MNs from these two ankle muscles as it is for MNs supplying the MG muscle alone. For MG-PBF pairings, the MN with lower CV was recruited first in the majority of trials for 13/24 pairs and in reverse order for 9/24 pairs. The recruitment sequence of coactive MNs supplying the MG and PBF muscles was, therefore, random with respect to axonal conduction velocity and not organized as predicted by the size principle. Taken together, these findings demonstrate for the first time, that the size principle can extend beyond the boundaries of a single muscle but does not coordinate all coactive muscles in a limb. (+info)
Myositis ossificans demonstrated by positive gallium-67 and technetium-99m-HMDP bone imaging but negative technetium-99m-MIBI imaging.
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Gallium-67-citrate and 99mTc-diphosphate bone imaging agents are localized in myositis ossificans, a tumor-like benign soft-tissue mass that makes it impossible to differentiate between malignant tumor and the infection/inflammatory process. We present such a myositis ossificans patient whose bone and 67Ga-citrate imagings showed increased uptake in the left thigh and two foci of the right gluteal region leading to inconclusive results. Technetium-99m-MIBI imaging showed the absence of substantial uptake in these regions. ACT scan confirmed myositis ossificans. The lack of 99mTc-MIBI uptake in myositis ossificans means that 99mTc-MIBI imaging may be useful in the differential diagnosis. (+info)
Predicting composition of leg sections with anthropometry and bioelectrical impedance analysis, using magnetic resonance imaging as reference.
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Magnetic resonance imaging (MRI) was used to evaluate and compare with anthropometry a fundamental bioelectrical impedance analysis (BIA) method for predicting muscle and adipose tissue composition in the lower limb. Healthy volunteers (eight men and eight women), aged 41 to 62 years, with mean (S.D.) body mass indices of 28.6 (5.4) kg/m2 and 25.1 (5.4) kg/m2 respectively, were subjected to MRI leg scans, from which 20-cm sections of thigh and 10-cm sections of lower leg (calf) were analysed for muscle and adipose tissue content, using specifically developed software. Muscle and adipose tissue were also predicted from anthropometric measurements of circumferences and skinfold thicknesses, and by use of fundamental BIA equations involving section impedance at 50 kHz and tissue-specific resistivities. Anthropometric assessments of circumferences, cross-sectional areas and volumes for total constituent tissues matched closely MRI estimates. Muscle volume was substantially overestimated (bias: thigh, -40%; calf, -18%) and adipose tissue underestimated (bias: thigh, 43%; calf, 8%) by anthropometry, in contrast to generally better predictions by the fundamental BIA approach for muscle (bias: thigh, -12%; calf, 5%) and adipose tissue (bias: thigh, 17%; calf, -28%). However, both methods demonstrated considerable individual variability (95% limits of agreement 20-77%). In general, there was similar reproducibility for anthropometric and fundamental BIA methods in the thigh (inter-observer residual coefficient of variation for muscle 3.5% versus 3.8%), but the latter was better in the calf (inter-observer residual coefficient of variation for muscle 8.2% versus 4.5%). This study suggests that the fundamental BIA method has advantages over anthropometry for measuring lower limb tissue composition in healthy individuals. (+info)
Experimental study of lymph node auto-transplantation in rats.
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OBJECTIVE: To observe the restoration of structure and function of auto-transplanted lymph nodes. METHODS: Inguinal lymph nodes in Spregue-Dawley (SD) rats were auto-transplanted by free implantation, or with an intact vascular pedicle, or by free transplantation with microvascular anastomosis, to the popliteal fossa where lymph nodes were removed. The observation methods included emission computerized tomographic (ECT) scanning, staining of China ink and methylthionine chloride to observe the histological changes. RESULTS: After four weeks, these vascularized nodes showed normal histological appearances and spontaneously reestablished afferent and efferent lymphatic reconnection with the surrounding lymphatic vessels. ECT lymphoscintigraphy with 99mTc-Dx showed that vascularized lymph nodes had restored their normal function. CONCLUSION: Vascularized lymph node transplantation is a useful method for draining extremity lymph edema. (+info)