Systemic Hormonal Unloading (SHU) in secondary hypertension: Addressing the long-term adverse cardiovascular outcomes

@#Excess hormone production from adrenal tumors caused by primary hyperaldosteronism or pheochromocytoma are common etiologies for secondary hypertension. Studies have shown that sustained long-term circulating hormones in excess affect the blood vessels and cardiac structures. Inflammation of cardiomyocytes leads to fibrosis and eventual cardiomyopathy and is clinically presented as arrhythmia, nonfatal myocardial infarction, heart failure, or even death. The tissue changes and/or impaired cardiac function are reversible if early diagnosis and removal of the adrenal tumor by unilateral adrenalectomy is done. However, the condition becomes challenging if the adrenal lesions are bilateral. This article introduces the concept of systemic hormonal unloading and will discuss the philosophy of quality of life in managing bilateral adrenal disease.

Effects of repetitive transcranial magnetic stimulation on neuronal excitability and ion channels in hindlimb unloading mice / 生物医学工程学杂志

Weightlessness in the space environment affects astronauts' learning memory and cognitive function. Repetitive transcranial magnetic stimulation has been shown to be effective in improving cognitive dysfunction. In this study, we investigated the effects of repetitive transcranial magnetic stimulation on neural excitability and ion channels in simulated weightlessness mice from a neurophysiological perspective. Young C57 mice were divided into control, hindlimb unloading and magnetic stimulation groups. The mice in the hindlimb unloading and magnetic stimulation groups were treated with hindlimb unloading for 14 days to establish a simulated weightlessness model, while the mice in the magnetic stimulation group were subjected to 14 days of repetitive transcranial magnetic stimulation. Using isolated brain slice patch clamp experiments, the relevant indexes of action potential and the kinetic property changes of voltage-gated sodium and potassium channels were detected to analyze the excitability of neurons and their ion channel mechanisms. The results showed that the behavioral cognitive ability and neuronal excitability of the mice decreased significantly with hindlimb unloading. Repetitive transcranial magnetic stimulation could significantly improve the cognitive impairment and neuroelectrophysiological indexes of the hindlimb unloading mice. Repetitive transcranial magnetic stimulation may change the activation, inactivation and reactivation process of sodium and potassium ion channels by promoting sodium ion outflow and inhibiting potassium ion, and affect the dynamic characteristics of ion channels, so as to enhance the excitability of single neurons and improve the cognitive damage and spatial memory ability of hindlimb unloading mice.

Study of nonlinear viscoelastic mechanical properties of degenerated intervertebral discs / Estudio de las propiedades mecánicas viscoelásticas no lineales de discos intervertebrales degenerados

SUMMARY: Biomechanical factors are important factors in inducing intervertebral disc degeneration, in this paper, the nonlinear viscoelastic mechanical properties of degenerated intervertebral discs were analyzed experimentally. Firstly, the loading and unloading curves of intervertebral discs before and after degeneration at different strain rates were compared to analyze the changes of their apparent viscoelastic mechanical properties; The internal stress/strain distribution of the disc before and after degeneration was then tested by combining digital image technology and fiber grating technology. The results show that the intervertebral disc is strain-rate- dependent whether before or after degeneration; The modulus of elasticity and peak stress of the degenerated disc are significantly reduced, with the modulus of elasticity dropping to 50 % of the normal value and the peak stress decreasing by about 55 %; Degeneration will not change the distribution of the overall internal displacement of the intervertebral disc, but has a greater impact on the superficial and middle AF; The stress in the center of the nucleus pulposus decreases, and the stress in the outer AF increases after degeneration. Degeneration has a great impact on the nonlinear viscoelastic mechanical properties of intervertebral disc, which has reference value for the mechanism, treatment and prevention of clinical degenerative diseases.

RESUMEN: Los factores biomecánicos son importantes en la inducción de la degeneración del disco intervertebral. En este estudio se analizaron experimentalmente las propiedades mecánicas viscoelásticas no lineales de los discos intervertebrales degenerados. En primer lugar se compararon las curvas de carga y descarga de los discos intervertebrales, antes y después de la degeneración, a diferentes velocidades de deformación para analizar los cambios aparentes de sus propiedades mecánicas viscoelásticas. La distribución interna de tensión/deformación del disco antes y después de la degeneración se probó luego combinando tecnología de imagen digital y tecnología de rejilla de fibra. Los resultados mostraron que el disco intervertebral depende de la velocidad de deformación antes o después de la degeneración; El módulo de elasticidad y la tensión máxima del disco degenerado se reducen significativamente, cayendo el módulo de elasticidad al 50 % del valor normal y la tensión máxima disminuyendo en aproximadamente un 55 %; La degeneración no cambiará la distribución del desplazamiento interno general del disco intervertebral, pero tiene un mayor impacto en la FA superficial y media; El estrés en el centro del núcleo pulposo disminuye y el estrés en el FA externo aumenta después de la degeneración. La degeneración tiene un gran impacto en las propiedades mecánicas viscoelásticas no lineales del disco intervertebral, que tiene valor de referencia para el mecanismo, tratamiento y prevención de enfermedades clínicas degenerativas.

A Successful Case of Central ECMO with a Transapical Left Ventricular Vent for Fulminant Myocarditis / 日本心臓血管外科学会雑誌

We report a successful case of fulminant myocarditis treated with central ECMO with a transapical left ventricular vent (TLVV). A 33-year-old man was diagnosed with fulminant myocarditis with acute biventricular failure. Using a cardio-pulmonary bypass, we introduced central ECMO with ascending aortic perfusion, right atrial venous drainage and TLVV. After ancillary circulation, his cardiac function gradually improved. The endotracheal tube was removed 5 days after the surgery (POD 5), and he was weaned from ECMO on POD 7 and discharged on POD 38. Although there are many cases in which peripheral veno-arterial ECMO (VA-ECMO) is used for fulminant myocarditis, there is a drawback to VA-ECMO : left ventricle (LV) unloading may be incomplete. Insufficient LV unloading may cause pulmonary congestion or disadvantage in myocardial recovery. TLVV can be used as a solution to unload the left ventricle. Central ECMO with TLVV should be useful therapy for fulminant myocarditis.

Systemic hormonal unloading in unilateral adrenalectomy in a patient with bilateral adrenal hyperplasia: A case report

Background @#Unilateral adrenalectomy has not been recommended in the guidelines as a treatment for primary hyperaldosteronism secondary to bilateral adrenal hyperplasia (BAH). Interestingly, recent studies have shown that increased circulation of aldosterone increased oxidative stress, cardiovascular (CV) complications such as atrial fi brillation, myocardial infarction and heart failure; and that unilateral adrenalectomy led to improved CV function. Therefore, recognizing the role of unilateral adrenalectomy in BAH, specifi cally for improved quality of life is important.@*Clinical case@# A 47‐year-old hypertensive (highest blood pressure [BP] 150/90 mmHg) woman had a severe headache, muscle weakness, polyuria, and polydipsia. Her serum potassium (K) was low at 3.1 mmol/L (3.5–5 mmol/L). Initial tests showed elevated plasma aldosterone, suppressed plasma renin activity and elevated aldosterone-renin ratio (6.61 ng/ dL, <0.1 ng/mL and 66, respectively). Plasma aldosterone after saline suppression test (12.70 ng/dL) confi rmed the diagnosis of primary aldosteronism (PA). MRI showed a well-defi ned, oval-shaped solid nodule in the medial limb of the left adrenal gland (1.8 x 1.2 cm). Bilateral adrenal vein sampling with adrenocorticotropic hormone (ACTH) stimulation test was compatible with BAH (cortisol-corrected aldosterone ratio pre-ACTH stimulation 1.29 and postACTH 1.66), with dominant aldosterone secreting left adrenal gland (7200 vs 3760 ng/dL). She was started on spironolactone 200 mg/day and amlodipine 10 mg/day and eventually shifted to eplerenone. Despite the optimal dose of eplerenone and amlodipine, she still experienced severe headaches, palpitations and breakthrough elevations of BP that led to her recurrent admissions. Eplerenone was shifted back to spironolactone (150-200 mg/day) with amlodipine dose (10 mg/day) normalizing her blood pressure and potassium level, yet with persistent headache and muscle weakness. Repeat imaging using CT scan with contrast showed consistent results. Postoperatively, with all medications discontinued the patient was asymptomatic, normotensive (110/70 mmHg) and normokalemic (4.0 mmol/L). One month later, her BP started to increase again at 140/80 mmHg and her K decreased to 3.4 mmol/L. Normalization of said parameters (BP:120/70 mmHg K: 4.1 mmol/L), with stabilization following lower doses of amlodipine (5mg/day) and spironolactone (25 mg/day). Also, all the symptomatology of the patient resolved completely.@*Conclusion@#This present case exemplifi es a unilateral adrenalectomy approach in BAH, which led to improvement in BP and K levels, despite low medication doses. Furthermore, symptom relief and improved quality of life, as desired outcomes, were achieved.

Value of systemic hormonal unloading in pheochromocytoma

@#Systemic unloading of adrenaline improves blood pressure (BP), but the effect on quality of life is not emphasized. This report aims to examine the outcome of systemic hormonal unloading through unilateral adrenalectomy in three pheochromocytoma cases.

Manejo pré-abate, parâmetros fisiológicos do estresse e seus efeitos na qualidade da carne suína: revisão / Pre-slaughter management, physiological parameters of stress and its effects on pork quality: review / Manejo pre matanza, parámetros fisiológicos del estrés y sus efectos sobre la calidad de la carne de cerdo: revisión

As atividades que antecedem o abate exigem um padrão e ainda algumas mudanças que priorizem em particular o bem-estar do animal. Dessa forma, o bem-estar na espécie suína assume grande importância quando se observa o manejo da granja ao frigorífico correlacionando com a atuação de fatores estressores que implicam em perdas tanto aos produtores quanto à indústria frigorífica. As falhas no manejo pré-abate podem resultar em carcaças com desvios, como carne pálida, flácida e exsudativa (PSE) e carne escura, firme e seca (DFD). Para assegurar o bem-estar e obter carne suína de qualidade é necessário que o manejo pré-abate seja realizado de forma adequada considerando as características comportamentais e fisiológicas dos animais, que se trata do ajuste com o ambiente e com os indivíduos, estabelecendo uma harmonia entre homem e animal. Em função do que foi relatado, objetivou-se revisar os fatores que interferem no manejo pré-abate de suínos e suas influências sobre os indicadores de estresse e qualidade da carne. O manejo pré-abate deve ser estabelecido conforme padrões conhecidos, no entanto, existe a necessidade de rever cada procedimento e estabelecer estudos regionais que envolvam todos os procedimentos, desde o embarque até o período de espera dos suínos na indústria frigorífica.(AU)

The activities that take place before slaughtering require a standard and also a few changes prioritizing the animal's welfare. Thus, the wellness of pigs is very important when analyzing their handling from the farm to the slaughterhouse, correlated with the stressing factors that imply in losses to both the producers and the meat industry. Flaws in the pre-slaughter management can result in carcasses presenting deviations, such as pale, limp and exudative (PSE) meat, and dark, firm and dry (DFD) meat. In order to ensure the well-being and obtain a quality pork meat, the pre-slaughter management must be appropriately carried out, considering the behavioral and physiological characteristics of the animals. Such characteristics are related to both the environment and the individuals, establishing harmony between humans and animals. Therefore, this paper aimed to review the factors interfering in the pre-slaughter management of pigs and their influence on stress indicators and meat quality. The pre-slaughter management must follow known standards; however, each procedure must be reviewed, developing regional studies involving all procedures, from shipping to the waiting period of the animals at the slaughterhouses.(AU)

Las actividades que anteceden la matanza exigen un estándar y aún algunos cambios que prioricen en particular el bienestar del animal. Así, el bienestar en la especie porcina es de gran importancia cuando se observa el manejo de la granja al matadero, correlacionando con la actuación de factores de estrés que implican en pérdidas tanto a los productores como a la industria frigorífica. Las fallas en el manejo pre matanza pueden resultar en caparazones con desvíos, como carne pálida, flácida y exudativa (PSE), y carne oscura, firme y seca (DFD). Para asegurar el bienestar y obtener carne porcina de calidad es necesario que el manejo pre matanza sea realizado de forma adecuada, considerando las características comportamentales y fisiológicas de los animales, pues se trata del ajuste con el ambiente y con los individuos, estableciendo armonía entre hombre y animal. De acuerdo a lo informado, se ha buscado revisar los factores que interfieren en el manejo pre matanza de porcinos y sus influencias sobre los indicadores de estrés y calidad de la carne. El manejo pre matanza debe ser establecido conforme estándares conocidos, sin embargo, existe la necesidad de revisar cada procedimiento y establecer estudios regionales que involucran todos los procedimientos, desde el embarque hasta el periodo de espera de los porcinos en el matadero.(AU)

Research on rapid unloading and positioning of new-type medical shelter at night / 医疗卫生装备

Objective To study a new method for fast unloading and positioning of medical shelter at night to accelerate the deployment speed of medical shelter system at night and improve the rapid reaction of medical support forces.Methods Laser marking device was used to indicate the three baseline for vehicle positioning based on three line positioning method,and then the position of the self-contained vehicle was determined.Reversing radar assisted in monitoring the vehicle position,and facilitated parking at a predetermined location.Results The problems such as low visibility were solved during the deployment at night,and the time consumed was decreased to 40 min for shelter positioning and unloading,so that the workload and artificial errors were both reduced greatly.Conclusion The method realizes medical shelter unloading efficiently with high practicability and flexibility.

Research on rapid unloading and positioning of new-type medical shelter at night / 医疗卫生装备

Objective To study a new method for fast unloading and positioning of medical shelter at night to accelerate the deployment speed of medical shelter system at night and improve the rapid reaction of medical support forces.Methods Laser marking device was used to indicate the three baseline for vehicle positioning based on three line positioning method,and then the position of the self-contained vehicle was determined.Reversing radar assisted in monitoring the vehicle position,and facilitated parking at a predetermined location.Results The problems such as low visibility were solved during the deployment at night,and the time consumed was decreased to 40 min for shelter positioning and unloading,so that the workload and artificial errors were both reduced greatly.Conclusion The method realizes medical shelter unloading efficiently with high practicability and flexibility.

The biomechanical effect of bilateral unloading knee brace with internal-external rotation on knee joint / 医用生物力学

Objective Aiming at reducing the restrictions on lower limbs imposed by traditional knee brace, a design scheme for knee brace complying with internal-external rotation is proposed. Methods By adding the internal-external hinge, the knee brace could help to release the degree of freedom (DOM) of internal-external rotation of the knee. In the experimental group, the subject was required to wear the bilateral unloading knee brace with or without internal-external hinges, respectively, while in the control group, the subject did not wear the knee brace. Then gait experiment and mechanical testing were conducted. Results In gait experiment, the bilateral unloading knee brace with internal-external hinges imposed less restriction on the knee than that from the knee brace without internal-external hinges, and it could also provide some distractive force for the knee joint. Conclusions The internal-external hinge design can help to reduce restrictions on the knee imposed from bilateral unloading knee brace.

Design and evaluation of an overall unloading knee brace / 医用生物力学

Objective To design an overall unloading knee brace, and analyze the relationship between the unloading force and the position of the brace as well as the thigh bracket-thigh pressure. Methods Based on biomechanical experimental platform, the mechanical and kinematic analysis on squatting down-standing upright motion was conducted to evaluate unloading capacity of the overall unloading knee brace. Results The unloading forces supplied by the brace ranged from 0 to 200 N. The forces were larger with the brace hinges installed on the front-top of the knee, and the unloading forces increased with the pressure between the thigh and thigh bracket increasing. Conclusions The proposed overall unloading knee brace can partly reduce knee force, and its unloading forces are related to the installation site of the brace as well as the elasticity of the belts.

Efeitos do desuso e da deficiência de estrógeno sobre a microarquitetura óssea e suas propriedades biomecânicas / Effects of disuse and estrogen deficiency on bone microarchitecture and its biomechanical properties

O objetivo desse estudo foi analisar se há diferenças no efeito do desuso e da deficiência de estrógeno sobre o tecido ósseo trabecular e cortical, e se estes efeitos influenciam na qualidade do tecido ósseo aumentando sua fragilidade. Para este estudo, 30 ratas Wistar com 19 semanas de idade foram distribuídas nos grupos: controle (CON), descarregamento dos membros posteriores (HLU) e ovariectomizado (OVX). As análises da densidade óssea in vivo (DXA) dos fêmures e tíbias e as dosagens plasmáticas de cálcio, fósforo, fosfatase alcalina, TRAP (espectrofotometria) e E2 (ELISA) foram realizadas no início e fim do experimento, com 19 e 27 semanas de idade respectivamente. Na 27a semana, os fêmures e as tíbias foram desarticulados e armazenados para avaliar a microestrutura do osso trabecular e cortical (microtomografia computadorizada), além das propriedades biomecânicas do colo femoral e da diáfise femoral e tibial (ensaio mecânico). O grupo HLU apresentou diminuição na concentração plasmática de cálcio e atividade da fosfatase alcalina total, diminuição na DMOa do fêmur com aumento na porosidade cortical e diminuição na resistência óssea, entretanto, não foram observadas estas alterações na tíbia. O grupo OVX apresentou diminuição nas concentrações plasmáticas de cálcio, diminuição da DMOa do fêmur, deterioração trabecular no fêmur e na tíbia, com maior deterioração nas trabéculas ósseas tibiais, sem alteração na resistência óssea em ambos os ossos. Esses resultados demonstram que apesar do grupo HLU e OVX apresentassem alterações na densidade mineral óssea e microarquitetura óssea, podemos concluir que o desuso determinou maior perda no tecido cortical e na resistência óssea em relação à deficiência de estrógeno. Portanto, as análises da estrutura do tecido cortical, como a porosidade cortical, podem ser preponderantes para prever o risco de fratura.

The objective of this study was to analyze whether there are differences in the effect of disuse and estrogen deficiency on trabecular and cortical bone tissue, and whether these effects influence the quality of bone tissue increasing its fragility. For this study, 30 Wistar rats with 19 weeks old, were divided into groups: control (CON), hindlimb unloading (HLU) and ovariectomy (OVX). In vivo analysis of bone density (DXA) from femurs and tibias and plasma levels of calcium, phosphorus, alkaline phosphatase, TRAP (spectrophotometry) and E2 (ELISA) were performed at the beginning and end of the experiment, and 19 age 27 weeks, respectively. In the 27th week, the femur and tibia were disjointed and stored to assess the microstructure of trabecular and cortical bone (microcomputed tomography) and biomechanical properties of the femoral neck and femoral shaft and tibial (mechanical tests). The HLU group showed a decrease in plasma calcium concentration and total alkaline phosphatase activity, decreased femoral BMAD with increased cortical porosity and decrease in bone strength, however, there were no such changes in the tibia. The OVX group showed a decrease in plasma concentrations of calcium, decreased femoral BMAD, trabecular deterioration in the femur and tibia, with further deterioration in the tibial trabecular bone, with no change in bone strength in both bones. These results demonstrate that although the HLU and OVX group showed changes in bone mineral density and bone microarchitecture, we can conclude that the in disuse determined higher cortical tissue loss and bone strength relative to estrogen deficiency. Therefore, the analysis of the cortical tissue structure, such as cortical porosity can be prevalent to predict fracture risk.

Effect of fluoride mouth rinses on various orthodontic archwire alloys tested by modified bending test: An in vitro study.

Objective: Fluorides can cause corrosion and degradation in mechanical properties of commonly used archwires by forming hydrofluoric acid HF and causing disruption of protective titanium oxide layer. Hence, the aim of this study was to assess the change in load deflection characteristics of Ni-Ti, Cu Ni-Ti, S.S, and β-Ti wires on immersing in fluoride mouth rinses of two types- Phosflur and neutral NaF mouth rinse utilizing a modified bending test and comparing it to control. Materials and Methods: Round preformed wires were immersed in 10 ml of control and test solution (Phosflur and S-Flo mouth rinse) for 1.5 hours and incubated at 37°C. Modified bending test was carried out to evaluate load-deflection characteristics of different wires using Instron. Analysis of variance (ANOVA) was applied to determine if statistically significant difference exist among the mean load values obtained at various deflections in control and test solutions. Results: There was no statistically significant reduction in load deflection characteristics of Ni-Ti, copper Ni-Ti, β-Ti, and S.S wires on immersing in Phosflur mouth rinse and neutral sodium fluoride mouth rinses as compared to control at 2.5 and 1 mm of deflection in unloading phase. Conclusion: Phosflur and a neutral sodium fluoride mouth rinse did not affect the mechanical bending properties of Ni-Ti, copper Ni-Ti, B-Ti, and SS wires in in vitro conditions.

Theoretical Estimation of Cannulation Methods for Left Ventricular Assist Device Support as a Bridge to Recovery

Left ventricular assist device (LVAD) support under cannulation connected from the left atrium to the aorta (LA-AA) is used as a bridge to recovery in heart failure patients because it is non-invasive to ventricular muscle. However, it has serious problems, such as valve stenosis and blood thrombosis due to the low ejection fraction of the ventricle. We theoretically estimated the effect of the in-series cannulation, connected from ascending aorta to descending aorta (AA-DA), on ventricular unloading as an alternative to the LA-AA method. We developed a theoretical model of a LVAD-implanted cardiovascular system that included coronary circulation. Using this model, we compared hemodynamic responses according to various cannulation methods such as LA-AA, AA-DA, and a cannulation connected from the left ventricle to ascending aorta (LV-AA), under continuous and pulsatile LVAD supports. The AA-DA method provided 14% and 18% less left ventricular peak pressure than the LA-AA method under continuous and pulsatile LVAD conditions, respectively. The LA-AA method demonstrated higher coronary flow than AA-DA method. Therefore, the LA-AA method is more advantageous in increasing ventricular unloading whereas the AA-DA method is a better choice to increase coronary perfusion.

Morphological changes in rat testes after Hindlimb Unloading model / 항공우주의학회지

BACKGROUND: The purpose of this study was to examine histological changes of testes induced by hindlimb unloading & position change of testis in mature adult male rats. METHOD: Eight month old (390~410g) 36 male Sprague-Dawley rats were weight-matched assigned to Ground Control (GC), Hindlimb Unloading (HU), Hindlimb Unloading & Testis Tie(HUT), Intra-abdominal Testis(IAT) for 24 days. Daily body weight was watched for status of animal. Testis weight, Seminiferous Tubule Diameter(STD), Seminiferous Tubule Perimeter(STP), Serminiferous Tubule Area(STA), Sertori Cell Height(SCH) were examined in each group. RESULTS: The 24-day hindlimb unloading of HU, HUT and IAT showed no significant change of body weight compared to GC. HUT maintained the weights, STD, STP, STA, SCH of their testes as GC while HU, IAT had significantly decreased the weights, STD, STP, STA of their testes. CONCLUSION: These results support that hindlimb unloading experiment induces serious morphological changes of testes. Therefore, on the hindlimb unloading experiment, IAT should be avoid or the effect of IAT should be correct. It will be necessary to study the pure effect of hindlimb unloading without IAT on the musculoskeltal system and so on which are associated with testosterone.

Influence of Hindlimb-unloading on the Morphology of Nerve Endings in Soleus Muscle Spindles / 航天医学与医学工程

Objective To investigate changes induced by hindlimb unloading in morphology of nerve endings in soleus muscle spindles.Method Hindlimb unloading model was simulated by tail suspension in female rats.Fast silver-staining was used to observe morphology of nerve endings of single muscle spindle in 7 d,14 d,21 d and 28 d tail-suspended and control rats.Result Nerve endings of muscle spindles in control rats were intact and clear,and there was no obvious abnormality in single soleus muscle spindle of 7 d tail-suspended rats.Slight fragmentation of nerve endings was observed in Equatorial Region of soleus muscle spindle in 14 d tail-suspended rats,while reduction in density and disruption of nerve endings were observed in soleus muscle spindle in 21 d tail-suspended rats.Serious degeneration and distortion of nerve endings were found in soleus muscle spindle in 28 d tail-suspended rats.Conclusion Hindlimb-unloading can induce time-related changes in morphology of nerve endings of muscle spindle in rats soleus muscle.

Influence of Various Packaging Methods and Controlling Method Toward Hidden Wet Pack after Steam Sterilization / 中华医院感染学杂志

OBJECTIVE To study the influence of various packing methods and controlling method toward the hidden wet pack after steam sterilization to ensure the sterilization quality and hygiene safety.METHODS The medical equipment was packed with three types of methods,then unloaded from the steam autoclave after being cooled at different time to observe their heating speed respectively.To choose two types of cotton fabric packaging methods,prolong the heating time,and cool in the steam autoclave for 30 minutes,then observe the heating speed of the inside pack and the dry qualification status after 12 hours respectively.RESULTS The heating speed was the fastest with the medical crinkly paper method;the heating speed of the inside pack didn't have any improvement after prolonging the heating time;the dry qualification rate had distinct difference between the two types of cotton fabric methods after 12 hours(P

Effect of Hindlimb Unloading of the Mechanical Properties of Bone in Mature Adult Male Rats: with Emphasis on the Bone Strength / 항공우주의학회지

BACKGROUND: The purpose of this study was to examine site-specific bone strength changes induced by hindlimb unloading in mature adult male rats. METHODS: Eight month old (390-410 g) 26 male Sprague-Dawley rats were weight-mated assigned to either a Ground control (CON) or a Hindlimb Unloading (HU) for 24 days. Daily body weight was watched for status of animal. Weight, BMD, strength, geometry of femur, tibia and humerus were examined in both groups. RESULTS: The 24-day hindlimb unloading of HU showed no significant change of body weight, total bone mineral, and bone geometry compared to CON. HU showed that the upper limb had maintained total bone mineral, bone geometry, and bone mechanical strength compared to CON. The hindlimb of HU had significantly decreased bone strength and ultimate stress (F/B) compared to CON. DEXA analysis of BMD and BMC in HU showed inconsistent changes at femur and tibia, although a relatively constant increase was shown in humerus. In HU rats, mechanical stress testing of compulsive fracture showed that more significant decreases in UL (ultimate load) and ultimate stress (F/B) was seen in femur than in tibia. CONCLUSION: These results support the theory that hindlimb unloading contribute to deleterious effects in femur rather than in tibia. It induced higher loss of mechanical bone strength in femur. In testing for BMD, pQCT, 2D, or 3D is recommended. DEXA is not recommended because it has inconsistent results and limitation with respect to the characteristics of area BMD (g/cm2) as a surrogate of volume BMD (g/cm3).

Experimental Osteoporosis in Tail Suspended Rat / 대한정형외과연구학회지

PURPOSE: To clarify whether the bone resorption in femur measured by the expression of OPG & RANK-L was increased in tail suspended rat. MATERIALS AND METHODS: Four-week-old female Sprague Dawley rats were divided into two groups. The experimental group (n=79) was housed and fed with 2 weeks of tail suspension, and reloaded for 8 weeks without tail suspension. The control group (n=46) was housed and fed for 10 weeks without tail suspension. Bone mineral densities, serum levels of ALP and TRAP were measured in both groups. The expressions of the mRNAs of OPG and RANK-L were analyzed by RT-PCR. RESULTS: The ALP and TRAP were increased in the experimental group during both tail suspension and reloading, which reflected the increased bone metabolism in the experimental group. In femur of the experimental group, the expression of the mRNA of RANK-L was increased during tail suspension, and the expression the mRNA of OPG was decreased. With reloading, the expression of the mRNA of RANK-L in femur was decreased, while the expression of the mRNA of OPG was increased.

Responses of Bone Mineral Density to Isometric Resistance Exercise During Hindlimb Unloading and Subsequent Recovery / 体力科学

The objective of this study was to investigate whether isometric resistance exercise (IRE) can attenuate musculoskeletal atrophy during unloading and accelerate its recovery during reloading. Twenty-six female Fischer 344 rats, aged 16 weeks, had their hindlimbs suspended for 3 weeks (unloading) ; 12 of these rats were allowed subsequent cage activity (reloading) for 3 weeks with or without IRE. IRE (stationary support on a cylindrical grid inclined 60 or 80 degrees) was done for 30 min/day, 6 days/week, with an additional load of 30% or 50% body mass attached to the tail during the unloading and reloading periods. The tibial bone and hindlimb skeletal muscles from four experimental and two age-matched control groups were evaluated with dual-energy X-ray absorptiometry, mechanical testing, and muscle mass measurement. Bone mineral density (BMD) was measured in the whole tibia and in 7 regions divided equally along the long axis of the epiphysis from proximal (R1) to distal (R7) . After unloading, fat-free dry mass (FFDM), bone mineral content (BMC), and BMD of the whole tibia decreased by 8%, 10%, and 6%, respectively. FFDM and BMC, but not BMD, returned to the levels of age-matched controls during reloading. Unloading-induced decreases in BMD were observed in the regions from the proximal epiphysis to the diaphysis (R1 to R4) and the distal epiphysis (R7) . The rate of decrease in BMD was regionally specific and was particularly pronounced (12%) in the most proximal region (R1) . These findings indicate regional variations in responses of BMD to skeletal unloading. The BMD in R2 to R4 remained less than that in age-matched control after reloading. No significant changes were observed in maximum breaking load, energy, and deformation after unloading and reloading. Hindlimb-unloading induced loss of mass in the soleus (38%), plantaris (14%), gastrocnemius (25%), tibialis anterior (8%), extensor digitorum longus ( 8%), and rectos lemons (17%) muscles, but the mass of muscles, except for the soleus muscle, recovered during reloading. IRE ameliorated the loss of mass in the soleus and gastrocnemius muscles during unloading but did not promote the recovery of mass in any muscles during reloading. Moreover, IRE showed no effect on bone responses after unloading and reloading. This lack of beneficial effects of IRE on osteopenia may be due, in part, to insufficient exerciseinduced load. We concluded that 1) regional analysis of BMD can be used to assess local bone metabolism, 2) the response of BMD to altered loading conditions does not necessarily depend on the response of muscle mass, 3) recovery from osteopenia progresses more slowly than that from sarcopenia, and a longer time than the unloading period is required to restore BMD. Further studies are needed to develop more effective countermeasures against osteopenia and sarcopenia.