Strategies for three dimensional deployment of tethered satellites

Tethered satellites deployed from the Space Shuttle have been proposed for diverse applications. A funda- mental issue in the utilization of tethers is quick deployment and retrieval of the attached payload. Inordinate librations of the tether during deployment and retrieval is undesirable. The structural damping present in the system is too low to contain the librations. Rupp [1] proposed to control the tether reel located in the parent spacecraft to alter the tension in the tether, which in turn changes the stiffness and the damping of the system. Baker[2] applied the tension control law to a model which included out of plane motion. Modi et al.[3] proposed a control law that included nonlinear feedback of the out-of plane tether angular rate. More recently, nonlinear feedback control laws based on Liapunov functions have been proposed. Two control laws are derived in [4]. The first is based on partial decomposition of the equations of motion and utilization of a two dimensional control law developed in [5]. The other is based on a Liapunov function that takes into consideration out-of-plane motion. It is shown[4] that the control laws are effective when used in conjunction with out-of-plane thrusting. Fujii et al.,[6] used the mission function control approach to study the control law including aerodynamic drag effect explicitly into the control algorithm.

The role of fsh and lh in the initiation of ovulation in rats and hamsters: a study using rabbit antisera to ovine fsh and lh

The relative rôles of FSH and LH in ovulation induction in immature and adult cycling rats and hamsters have been evaluated. Both heterologous purified pituitary hormones and homologous crude pituitary extracts have been used as ovulatory stimuli in immature animals primed with PMSG. Well-characterized FSH and LH antisera have been used in the above model systems to achieve specific neutralization of FSH and LH. The present study revealed that LH is the physiological trigger needed for induction of ovulation in both rats and hamsters and FSH cannot, by itself, induce ovulation in the total absence of LH.

Evaluation of anti-inflammatory potential of Chloranthus erectus (Buch.-Ham.) Verd. leaf extract in rats

Aim of the study: Chloranthus erectus (Buch.-Ham.) Verdcourt (Chloranthaceae) is a shrub native to tropical and temperate zone of Eastern Himalaya of India and South-East Asia and have traditionally been used as a folklore medicine to treat localised swelling, joint pain, skin inflammation, fever and bodyache. In this study, an attempthas been made to demonstrate the anti-inflammatory activity of methanol extract obtained from Chloranthus erectus leaves (MECEL) in acute, sub-acute and chronic mouse models. Materials and methods: Inflammation in the hind paw of Wistar albino rat was induced by carrageenan, histamine and serotonin, and tissue granuloma pouch was induced by cotton pellet method. Antiinflammatory drug-phenylbutazone was used as standard drug for comparison. Results: In acute carrageenan-induced rat hind paw edema, oral administration of MECEL at 200 mg/kg produced significant inhibition of edema by 38.34 % (p<0.01) while the histamine- and serotonin-induced sub-acute model, the inhibition of paw edema reached 52.54 % (p < 0.001) and 25.5 % (p < 0.01), respectively. in a 7-day study, MECEL at 20 and 50 mg/kg produced significant suppression of cotton pellet-induced tissue granuloma formation in rats. Conclusions: This preliminary study revealed that the methanol extract of Chloranthus erectus exhibited significant anti-inflammatory activity in the tested models, and may provide the scientific rationale for its popular folk medicine as anti-inflammatory agent.

Model For Regulation Of Delta-Aminolevulinate Synthetase Induction In Rat-Liver

A reciprocal relationship exists between the cytochrome P-450 content and d-aminolaevulinate synthetase activity in adult rats. In young rats the basal d-aminolaevulinate synthetase activity is higher and the cytochrome P-450 content is lower compared with the adult rat liver. Administration of allylisopropylacetamide neither induces the enzyme nor causes degradation of cytochrome P-450 in the young rat liver, unlike adult rat liver. Allylisopropylacetamide fails to induce d-aminolaevulinate synthetase in adrenalectomized–ovariectomized animals or intact animals pretreated with successive doses of the drug, in the absence of cortisol. The cortisol-mediated induction of the enzyme is sensitive to actinomycin D. Allylisopropylacetamide administration degrades microsomal haem but not nuclear haem. Haem does not counteract the decrease in cytochrome P-450 content caused by allylisopropylacetamide administration, but there is evidence for the formation of drug-resistant protein-bound haem in liver microsomal material under these conditions. Phenobarbital induces d-aminolaevulinate synthetase under conditions when there is no breakdown of cytochrome P-450. On the basis of these results and those already published, a model is proposed for the regulation of d-aminolaevulinate synthetase induction in rat liver.

Simultaneous effect of lead and cadmium on granulosa cells: A cellular model for ovarian toxicity

Lead (Pb) and cadmium (Cd) are known reproductive toxicants, which accumulate in granulosa cells of the ovary. Female Charles foster rats were treated with sodium acetate (control), lead acetate and cadmium acetate either alone or in combination at a dose 0.05 mg/kg body weight intra-peritoneally for 15 days daily. Animals were killed at proestrous stage and granulosa cells were isolated from the ovaries. Binding of I-125-luteinizing hormone (I-125-LH), I-125-follicle stimulating hormone (I-125-FSH) and 17 beta-hydroxysteroid dehydrogenase activity were measured. As these receptors are localized on the surface of the cell membrane, we also estimated the membrane parameters of these cells. Our results demonstrated that both lead and cadmium caused a significant reduction in gonadotropin binding, which altered steroidogenic enzyme activity of granulosa cells. These changes exhibited a positive correlation with membrane changes of the granulosa cells.

Antiulcerogenic activity of Terminalia chebula fruit in experimentally induced ulcer in rats

Objective: The present study is to evaluate the antiulcer effect of hydroalcoholic (70%) extract of Terminalia chebula fruit. Materials and methods: Aspirin, ethanol and cold restraint stress-induced ulcer methods in rats were used for the study. The effects of the extract on gastric secretions, pH, total and free acidity using pylorus ligated methods were also evaluated. Results: Animals pretreated with doses of 200 and 500 mg/kg hydroalcoholic extract showed significant reduction in lesion index, total affected area and percentage of lesion in comparison with control group (P < 0.05 and P < 0.01) in the aspirin, ethanol and cold restraint stress-induced ulcer models. Similarly extracts increased mucus production in aspirin and ethanol-induced ulcer models. At doses of 200 and 500 mg/kg of T. chebula extract showed antisecretory activity in pylorus ligated model, which lead to a reduction in the gastric juice volume, free acidity, total acidity, and significantly increased gastric pH. Discussion and conclusion: These findings indicate that hydroalcoholic extract of the fruit T. chebula displays potential antiulcerogenic activity. This activity thus lends pharmacological credence to the suggested use of the plant as a natural remedy in the treatment or management of ulcer.

Modulating effect of gelonin gp330 conjugate on Heymann's nephritis induced in rats - A pathomorphological evaluation

Heymann's nephritis (HN) in rats induced by injecting renal proximal tubule brush border protein gp330, is an animal model replicating human autoimmune membranous glomerulonephritis(1). Endogenous IgG gets deposited between the foot processes in the epithelial side of the glomerulus and causes complement-mediated membrane injury, leading to proteinuria and basement membrane thickening. We investigated the effect of a toxin, gelonin conjugated to gp330 and targetted against antigp330-producing cells in ameliorating immune injury and nephrotic state in rats. The groups of animals injected with purified gp330 revealed by immunofluorescence, characteristic granular deposits of IgG along the basement membrane. The rats intravenously injected with gelonin gp330 conjugate, four days after the antigenic challenge with gp330 in two doses, showed amelioration of the nephrotic state and appreciable reduction in glomerular IgG deposits against immune injury. This substantiates our earlier biochemical results and corroborates the possibility of using toxins conjugated to specific antigen in treating antibody-mediated autoimmune diseases.

The force distribution function of an oscillator model of polymer stretching at constant velocity

Recent simulations of the stretching of tethered biopolymers at a constant speed v (Ponmurugan and Vemparala, 2011 Phys. Rev. E 84 060101(R)) have suggested that for any time t, the distribution of the fluctuating forces f responsible for chain deformation is governed by a relation of the form P(+ f)/ P(- f) = expgamma f], gamma being a coefficient that is solely a function of v and the temperature T. This result, which is reminiscent of the fluctuation theorems applicable to stochastic trajectories involving thermodynamic variables, is derived in this paper from an analytical calculation based on a generalization of Mazonka and Jarzynski's classic model of dragged particle dynamics Mazonka and Jarzynski, 1999 arXiv:cond-\textbackslashmat/9912121v1]. However, the analytical calculations suggest that the result holds only if t >> 1 and the force fluctuations are driven by white rather than colored noise; they further suggest that the coefficient gamma in the purported theorem varies not as v(0.15)T-(0.7), as indicated by the simulations, but as vT(-1).

Improvement in Bone Properties by Using Risedronate Adsorbed Hydroxyapatite Novel Nanoparticle Based Formulation in a Rat Model of Osteoporosis

A superior drug formulation capable of achieving efficient osteogenesis is in imperative demand for the treatment of osteoporosis. In the present study we investigated the potential of using novel risedronate-hydroxyapatite (HA) nanoparticle based formulation in an animal model of established osteoporosis. Nanoparticles of HA loaded with risedronate (NHLR) of various sizes (80-130 nm) were generated for bone targeted drug delivery. Three months after ovariectomy, 36 ovariectomized (OVX) rats were divided into 6 equal groups and treated with various doses of NHLR (500,350 and 250 mu g/kg intravenous single dose) and sodium risedronate (500 mu g/kg, intravenous single dose). Untreated OVX and sham OVX served as controls. One month after drug administration, the left tibia and femur were tested for bone mechanical properties and histology, respectively. In the right femur, bone density was measured by method based on Archimedes principle and bone porosity analyses were performed using X-ray imaging. NHLR (250 mu g/kg) showed a significant increase in bone density and reduced bone porosity when compared with OVX control. Moreover, NHLR (250 mu g/kg) significantly increased bone mechanical properties and bone quality when compared with OVX control. The results strongly suggest that the NHLR, which is a novel nanoparticle based formulation, has a therapeutic advantage over risedronate sodium monotherapy for the treatment of osteoporosis in a rat model of postmenopausal osteoporosis.

Osteoprotective effect of propranolol in ovariectomized rats: a comparison with zoledronic acid and alfacalcidol

Currently beta-adrenergic receptor blockers are considered to be potential drugs under investigation for preventive or therapeutic effect in osteoporosis. However, there is no published data showing the comparative study of beta-blockers with well accepted agents for the treatment of osteoporosis. To address this question, we compared the effects of propranolol with well accepted treatments like zoledronic acid and alfacalcidol in an animal model of postmenopausal osteoporosis. Five days after ovariectomy, 36 ovariectomized (OVX) rats were divided into 6 equal groups, randomized to treatments zoledronic acid (100 mu g/kg, intravenous single dose); alfacalcidol (0.5 mu g/kg, oral gauge daily); propranolol (0.1 mg/kg, subcutaneously 5 days per week) for 12 weeks. Untreated OVX and sham OVX were used as controls. At the end of treatment serum calcium and alkaline phosphatase were assayed. Femurs were removed and tested for bone density, bone porosity, bone mechanical properties and trabecular micro-architecture. Propranolol showed a significant decrease in alkaline phosphatase levels and bone porosity in comparison to OVX control. Moreover, propranolol significantly improved bone density, bone mechanical properties and inhibited the deterioration of trabecular microarchitecture when compared with OVX control. The osteoprotective effect of propranolol was comparable with zoledronic acid and alfacalcidol. Based on this comparative study, the results strongly suggest that propranolol can be a candidate therapeutic drug for the management of postmenopausal osteoporosis.

Zoledronic acid in combination with alfacalcidol has additive effects on trabecular microarchitecture and mechanical properties in osteopenic ovariectomized rats

We conducted the present study to investigate the therapeutic effects of the antiresorptive agent zoledronic acid (ZOL), alone and in combination with alfacalcidol (ALF), in a rat model of postmenopausal osteoporosis. Female Wistar rats were ovariectomized (OVX) or sham-operated at 3 months of age. Twelve weeks post surgery, rats were randomized into six groups: (1) sham + vehicle, (2) OVX + vehicle, (3) OVX + ZOL (100 mu g/kg, i.v. single dose), (4) OVX + ZOL (50 mu g/kg, i.v. single dose), (5) OVX + ALF (0.5 mu g/kg, oral gauge daily) and (6) OVX + ZOL (50 mu g/kg, i.v. single dose) + ALF (0.5 mu g/kg, oral gauge daily) for 12 weeks. After treatment, we evaluated the mechanical properties of the lumbar vertebra and femoral mid-shaft. Femurs were also tested for bone density, porosity and trabecular micro-architecture. Biochemical markers in serum and urine were also determined. With respect to improvement in the mechanical strength of the lumbar spine and the femoral mid-shaft, the combination treatment of ZOL and ALF was more effective than each administered as a monotherapy. Moreover, combination therapy using ZOL and ALF preserved the trabecular micro-architecture and cortical bone porosity. Furthermore, the combination treatment of ZOL and ALF corrected the decrease in serum calcium and increase in serum alkaline phosphatase and the tartarate-resistant acid phosphatase level better than single-drug therapy using ZOL or ALF in OVX rats. In addition, the combination treatment of ZOL and ALF corrected the increase in urine calcium, phosphorous and creatinine levels better than single-drug therapy using ZOL or ALF in OVX rats. These data suggest that the combination treatment of ZOL and ALF has a therapeutic advantage over each monotherapy for the treatment of osteoporosis.

Development, in vitro and in vivo characterization of zoledronic acid functionalized hydroxyapatite nanoparticle based formulation for treatment of osteoporosis in animal model

We investigated the potential of using novel zoledronic acid (ZOL)-hydroxyapatite (HA) nanoparticle based drug formulation in a rat model of postmenopausal osteoporosis. By a classical adsorption method, nanoparticles of HA loaded with ZOL (HNLZ) drug formulation with a size range of 100-130 nm were prepared. 56 female Wistar rats were ovariectomized (OVX) or sham-operated at 3 months of age. Twelve weeks post surgery, rats were randomized into seven groups and treated with various doses of HNLZ (100, 50 and 25 mu g/kg, intravenous single dose), ZOL (100 mu g/kg, intravenous single dose) and HA nanoparticle (100 mu g/kg, intravenous single dose). Untreated OVX and sham OVX served as controls. After three months treatment period, we evaluated the mechanical properties of the lumbar vertebra and femoral mid-shaft. Femurs were also tested for trabecular microarchitecture. Sensitive biochemical markers of bone formation and bone resorption in serum were also determined. With respect to improvement in the mechanical strength of the lumbar spine and the femoral mid-shaft, the therapy with HNLZ drug formulation was more effective than ZOL therapy in OVX rats. Moreover, HNLZ drug therapy preserved the trabecular microarchitecture better than ZOL therapy in OVX rats. Furthermore, the HNLZ drug formulation corrected increase in serum levels of bone-specific alkaline phosphatase, procollagen type I N-terminal propeptide, osteocalcin, tartrate-resistant acid phosphatase 5b and C-telopeptide of type 1 collagen better than ZOL therapy in OVX rats. The results strongly suggest that HNLZ novel drug formulation appears to be more effective approach for treating severe osteoporosis in humans. (C) 2014 Elsevier B.V. All rights reserved.

Changes in the expression of DNA double strand break repair genes in primordial follicles from immature and aged rats

Oocytes present at birth undergo a progressive process of apoptosis in humans and other mammals as they age. Accepted opinion is that no fresh oocytes are produced other than those present at the time of birth. Studies have shown that DNA repair genes in oocytes of mice and women decline with age, and lack of these genes show higher DNA breaks and increased oocyte death rates. In contrast to the ethical problems associated with monitoring the changes in DNA double-strand breaks in oocytes from young and old humans, it is relatively easy to carry out such a study using a rodent model. In this study, the mRNA levels of DNA repair genes are compared with protein products of some of the genes in the primordial follicles isolated from immature (18-20 days) and aged (400-450 days) female rats. Results revealed a significant decline in mRNA levels of BRAC1 (P < 0.01), RAD51 (P < 0.05), ERCC2 (P < 0.05), and H2AX (P < 0.01) of DNA repair genes and phospho-protein levels of BRAC1 (P < 0.01) and H2AX (P < 0.05) in primordial follicles of aged rats. Impaired DNA repair is confirmed as a mechanism of oocyte ageing. (C) 2014 Reproductive Healthcare Ltd. Published by Elsevier Ltd. All rights reserved.

Additive effect of zoledronic acid and alfacalcidol in the treatment of disuse osteoporosis in rats

Objectives: Disuse by bed rest, limb immobilization or space flight causes rapid bone loss. We conducted the present study to investigate the therapeutic effects of zoledronic acid (ZOL), alone and in combination with alfacalcidol (ALP) in a rat model of disuse osteoporosis. Methods: In the present study, 3-month-old male Wistar rats had their right hind-limb immobilized (RHLI) for 10 weeks to induce osteopenia, then were divided into four groups: 1 - RHLI positive control; 2 - RHLI plus ZOL (50 mu g/kg, i.v. single dose); 3 - RHLI plus ALP (0.5 mu g/kg, oral gauge daily); 4- RHLI plus ALP (0.5 mu g/kg, oral gauge daily) plus ZOL (50 mu g/kg, i.v. single dose) for another 10 weeks. One group of non-immobilized rats was used as negative control. At the end of the treatment, the femurs were removed and tested for bone porosity, bone mechanical properties, and bone dry and ash weight. Results: Combination therapy with ZOL plus ALP was more effective in decreasing bone porosity than each drug administered as monotherapy in RHLI rats. With respect to improvement in the mechanical strength of the femoral mid-shaft, the combination treatment of ZOL plus ALP was more effective than each drug administered as a monotherapy. Moreover, combination therapy using ZOL plus ALF was more effective in improving dry bone and ash weight, than single-drug therapy using ZOL or ALP in RHLI rats. Conclusions: These data suggest that combination therapy with ZOL plus ALP represents a potentially useful therapeutic option for the treatment of disuse osteoporosis. (C) 2014 Elsevier Editora Ltda. All rights reserved.