114 resultados para hindlimb


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Myelodysplasia is a general term referring to abnormal development of the spinal cord. Unless associated with vertebral malformations, it can be difficult to distinguish clinically from other causes of spinal cord disease. These case reports describe the clinical and pathological findings in two calves with a distinctive non-progressive pelvic limb ataxia. The syndrome was observed in two calves on a large, extensively managed beef cattle property near Richmond, north Queensland. Both calves had similar clinical signs, including hindlimb ataxia with swaying of the pelvis and a well-coordinated bilateral hopping-like action. The differential diagnoses are discussed. A focal or diffuse myelodysplasia should be suspected in calves that have exhibited a non-progressive hindlimb ataxia from birth.

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In anesthetized rats, we characterized the contributions of norepinephrine (NE) and ATP to changes in tail and hindlimb (femoral) vascular resistances (TVR and FVR, respectively) evoked by three patterns of sympathetic stimulation: 1) couplets (2 impulses at 20 Hz), 2) short trains (20 impulses at 20 Hz), and 3) a natural irregular pattern previously recorded from a sympathetic fiber innervating the rat tail artery. All stimuli evoked greater changes in TVR than FVR. Judging from the effects of the -adrenoceptor antagonist phentolamine, the purinergic receptor antagonist suramin, or ,-methylene ATP (which desensitizes P2X receptors), we propose that NE has a major role in the constriction evoked by the couplet, as well as by the short train and by the low- and high-frequency components of the natural pattern, but that considerable synergy occurred between the actions of ATP and NE. This contrasts with previous in vitro studies that indicated that ATP dominates vascular responses evoked by sympathetic stimulation with a few impulses at low frequency and that NE dominates responses to longer trains or at high frequencies.

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Contraction-mediated lipolysis increases the association of lipid droplets and mitochondria, indicating an important role in the passage of fatty acids from lipid droplets to mitochondria in skeletal muscle. PLIN3 and PLIN5 are of particular interest to the lipid droplet–mitochondria interaction because PLIN3 is able to move about within cells and PLIN5 associates with skeletal muscle mitochondria. This study primarily investigated: 1) if PLIN3 is detected in skeletal muscle mitochondrial fraction; and 2) if mitochondrial protein content of PLIN3 and/or PLIN5 changes following stimulated contraction. A secondary aim was to determine if PLIN3 and PLIN5 associate and whether this changes following contraction. Male Long Evans rats (n = 21;age, 52 days; weight = 317 6 g) underwent 30 min of hindlimb stimulation (10 msec impulses, 100 Hz/3 sec at 10–20 V; train duration 100 msec). Contraction induced a ~50% reduction in intramuscular lipid content measured by oil red-O staining of red gastrocnemius muscle. Mitochondria were isolated from red gastrocnemius muscle by differential centrifugation and proteins were detected by western blotting. Mitochondrial PLIN5 content was ~1.6-fold higher following 30 min of contraction and PLIN3 content was detected in the mitochondrial fraction, and unchanged following contraction. An association between PLIN3 and PLIN5 was observed and remained unaltered following contraction. PLIN5 may play a role in mitochondria during lipolysis, which is consistent with a role in facilitating/regulating mitochondrial fatty acid oxidation. PLIN3 and PLIN5 may be working together on the lipid droplet and mitochondria during contraction-induced lipolysis.

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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In previous studies using bilateral carotid occlusion in conscious freely moving rats we suggested that aortic baroreceptors may play a more important role in the regulation of hindlimb than in renal and mesenteric vascular resistances. In the present study we performed electrical stimulation of the aortic baroreceptor nerve and analyzed the changes in mean arterial pressure and in hindlimb, renal, and mesenteric vascular resistances. All the experiments were performed under urethan anesthesia. Unilateral electrical stimulation (3 V, 2 ms, 50 Hz) of the aortic baroreceptor nerve produced a fall in arterial pressure (-27 +/- 3 mmHg) and an important reduction in hindlimb vascular resistance (-43 +/- 5%), with an increase in renal (+3 +/- 14%) and mesenteric (+48 +/- 12%) vascular resistances. Similar changes in arterial pressure as well as in the resistance of the three vascular beds studied were also observed during electrical stimulation of the aortic baroreceptor nerve in rats with bilateral carotid baroreceptor denervation or in rats treated with methylatropine. The data obtained with electrical stimulation indicated that aortic baroreceptors play a more important role in the regulation of blood flow in hindlimb than in renal and mesenteric vascular beds.

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We investigated the importance of daily free activity in the cage and body weight gain during the recovering of bone structural and mechanical properties in growing rats after hindlimb unloading. Eight-week-old male Wistar rats were randomly divided into control (CG, n=24) and suspended (SG, n=24) groups. Animals from SG underwent a four-week hindlimb unloading period by tail-suspension. Animals from CG and those from SG after release were kept in collective cages and sacrificed at the age of 12, 16 and 20 weeks. Both femurs were removed and its area, bone mineral density (BMD), resistance to failure and stiffness were determined. Four-week hindlimb unloading decreased (p < 0.05) body weight (CG, 373.00 +/- 9.47 vs. SG, 295.86 +/- 9.19 g), BMD (CG, 0.19 +/- 0.01 vs. SG, 0.15 +/- 0.01 g/cm(2)), bone resistance to failure (CG, 147.75 +/- 5.05 vs. SG, 96.40 +/- 5.95 N) and stiffness (CG, 0.38 +/- 0.01 vs. SG, 0.23 +/- 0.02 N/m). Eight weeks of free activity in cage recovered (p > 0.05) the body weight (CG, 472.75 +/- 14.11 vs. SG, 444.75 +/- 18.91 g), BMD (CG, 0.24 +/- 0.01 vs. SG, 0.22 +/- 0.01 g/cm(2)), bone resistance to failure (CG, 195.73 +/- 10.06 vs. SG, 178.45 +/- 8.48 N) and stiffness (CG, 0.56 +/- 0.02 vs. SG, 0.47 +/- 0.03 N/m) of SG animals. Body weight correlated strongly with bone structural and mechanical properties (p < 0.0001). In conclusion, free activity in the cage associated with body weight gain restored bone structural and mechanical properties in growing rats after hindlimb unloading.

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Aging is associated with decline in muscle mass and strength and reduced bone density. Age-related bone loss is a primary factor in osteoporosis and all individuals are potential candidates for osteoporosis because bone loss with aging occurs in men and women, but less studied in men. To examine the appropriateness of hindlimb elevation, by tail suspension as a model for diminished mechanical loading, and to determine the influence of age on bone responsiveness to skeletal unloading, we use dual X ray absorptiometry (DXA) and digital radiographic images to analyze the response of the femur from mature rats to biomechanical loads. Femurs from male Wistar rats (9-mo-old) were scanned using DXA and DIGORA and measures obtained in ephipyseal and diaphyseal regions of interest. The mechanical testing was divided into compression load to fracture the head and a three-point bending load to fracture the femur middiaphysis. In femoral epiphysis from hindlimb unload (HU), animals presented significant differences between mineral bone content and density assessed by DXA. Detailed regions of femoral epiphysis (head, throcanteric fossa, throcanter and metaphysis) presented significant lower values from radiographic density. Only compressive load necessary to fracture the femoral head neck was also significantly diminished in HU animals. Disuse induced, as in elderly patients, deterioration of the trabecular bone architecture with critical effect on bone fragility. Rats with 21 days of hindlimb unloading can simulate disuse, suggesting that certain sub-regions of their aging bones are more susceptible to fracture, while other, i.e. diaphyses, are not.

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Introduction: Bone strength is influenced by a number of different determinants, such as mass, size, geometry and also by the intrinsic material properties of the tissue. Aims: The structure and mechanical properties of the femur were analyzed in aged (14 mo-old) animals submitted to hindlimb unloading (HU) for 21 days. Methods: Twenty Wistar rats were randomly divided into Control and HU groups and the femur was submitted to dual X ray absorptiometry (DXA), DIGORA radiographic density, mechanical compression testing and Knoop microhardness analyse in cortical and cancellous bone. Results: Femurs from HU group presented significantly lower failure load, decreased bone mineral density (BMD)/bone mineral content (BMC) in whole bone; proximal/distal epiphysis and middiaphyseal cortical bone measured by DXA were similar in the two groups; radiographic density from areas in proximal epiphysis was significantly lower in HU group, and microhardness measured at periosteal and endosteal levels were also signifcantly diminished in HU compared with Control group. Conclusion: Disuse induced damage in the trabecular femoral bone architecture with decisive effect on the head and trochanteric fossa, which became weaker. Bone diaphyseal cortical hardness also suffered effect of unloading, probably related to osteocyte/osteoblast activity.

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Objective: The purpose of this study was to determine the impact of pharmacologic treatment with cilostazol and pentoxifylline on gait biomechanics of ischemic rat hindlimbs compared with nonischemic controls. Methods: An experimental study was designed using 30 Wistar rats divided into five groups (n = 6): control (C); ischemia (I) - animals submitted to left common iliac artery interruption without pharmacologic treatment; pentoxifylline (Pen) - rats submitted to procedure and treated with pentoxifylline 3 mg/kg twice a day for 6 weeks; cilostazol (Cil) - animals submitted to procedure and treated with cilostazol 30 mg/kg twice a day for 6 weeks; and sham (S) - animals submitted to procedure without artery interruption. Gait analysis was performed using a computed treadmill. Time, number, and duration of each hindlimb contact were obtained. The total number of contacts (TNC) and the total duration of contacts (TDC) were compared between left and right hindlimb and among groups. Left hindlimb ischemic incapacitation index (LHII) was defined by the formula: LHII = (1 - TNCleft x TDCleft/TNCright x TDCright) x 100 Results: Left hindlimb TNC values were twofold lower in I, Pen, and Cil groups than in C and S groups (P < .01). In I, Pen, and Cil groups, TNC values for the left hindlimb were half of the right hindlimb ones (P < .01). Left hindlimb TDC values were lower in I and Pen groups than the other groups (P < .01). Cil group presented twofold increased values, not different from C and S groups (P = 0.16). Right hindlimb TNC values were greater for I group (P < .01). LHII was around zero in C and S groups and 82 in both I and Pen groups (P < .01). Cil group presented a LHII of 42; higher than C and S groups, but lower than I and Pen groups (P < .01). Conclusions: Cilostazol at a dose of 30 mg/kg twice a day promoted improvement in gait performance in rats submitted to chronic hindlimb ischemia. Pentoxifylline at a dose of 3 mg/kg twice a day did not show this effect. (J Vasc Surg 2012;56:476-81.)