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PubMed2000

[Effects of tail suspension on learning and memory function of mice].

Objective. To study the effects of simulated weightlessness on learning and memory capability of the brain. Method. Accuracy fraction, error frequency and pass rate were observed among control, restrained control, tail suspended (TS) control, restrained, and tail suspended mice in square water maze tests. And latent period and error time were observed in control and 30 degrees tail suspension mice in step down test. Result. The indices did not change significantly during learning period. Accuracy fraction of tail suspended group was reduced significantly in the tests as compared with pretest values. In step down test, latent period and error time showed no difference between TS 5 h and 2 d in untrained mice, but shortened evidently after TS 2 d and prolonged after TS 7 d in trained mice, which suggested the degradation of learning and memory ability after TS 5 h and 2 d respectively. Conclusion. Acute tail suspension depressed brain's learning ability and quality, while tail suspension of 7 d and 12 d impaired the spatial memory in mice.

Animals↗

PubMed2002

Air-righting responses to chronic hindlimb suspension and ambulation recovery in adult rats.

Laouris et al. (1990) reported that the development of air-righting in growing new-born rats was clearly suppressed when their neck and/or back rotations were prevented. Thus, it is suggested that the neck and back muscles play an important role for a quick righting in response to drop from supine position. Further, we reported that an inhibiton of posture adjustment in response to head-down drop from a height of approximately 30 cm following chronic hindlimb suspension of adult rats was accompanied by a decrease of electromyogram (EMG) activity in both neck and back muscles (Kawano et al., 2002). However, it is still unclear how the air-righting performance is influenced by hindlimb suspension in adult rats. Thus, the effects of chronic hindlimb suspension of adult rats on the patterns and time of air-righting and role of neck and back muscles in the air-righting were investigated in the current study.

Animals↗

PubMed2003

[Morphofunctional changes in the endocrine system of male rats during microgravity and suspension].

Morphofunctional changes in somatotrophs and gonadotrophs of the adenohypophysis and Leydig's cells in the testicles were investigated histologically and hystomorphometrically in male rats following microgravity or tail-suspension. Deficient loading of the musculoskeletal system in microgravity was shown to suppress the functional activity of somatotrophs, gonadotrophs and, seemingly, Leydig's cells. As a consequence, blood levels of the growth hormone and testosterone reduced in the space-flown rats. Reduction of the production of the main anabolic hormones is one of the causes for growth inhibition, prevalence of catabolism and consequent muscular atrophy and osteopenia. Simulation of the lack of weight loading inherent to the zero-g environment by suspension also leads to suppression of the somatotrophs activity, whereas the concentration and functional activity of gonadotrophs make a sharp rise. Proliferation of Leydig's cells in the testicles was noted to be very high despite desolation of the seminal canals and disintegration of the testicle epithelium. These findings drive to the conclusion that suspension affects deeply the spermiogenous and androgenous functions of the testicle which is not observed in animals exposed to microgravity. These differences evidence that genesis of the musculoskeletal atrophy in the suspended and space-flown rats was dissimilar.

Animals↗

PubMed2002

Effects of chronic hindlimb suspension on landing performance in response to head-down drop in rats.

Effects of hindlimb unloading and reloading on the patterns of landing and posture adjustment in response to head-down drop from a height of approximately 30 cm were investigated in rats. Seven weeks old male Wistar rats were hindlimb-unloaded by tail suspension for 9 consecutive weeks. Motor tests were performed immediately after the termination of suspension and recovery patterns were checked during 8 weeks of ambulation recovery. Although all of the control rats were able to land smoothly by using the four limbs as the shock absorber, the unloaded rats landed by hitting their abdomen. The hindlimb-unloaded, but not control, rats dorsi-flexed their trunk during fall. The mean angle of abdominal side was approximately 145 degrees in control and approximately 215 degrees in unloaded rats. Even though such phenomena were maintained for approximately 12 hours, the response of the trunk angle recovered significantly 2 days later. However, it was not normalized completely even after 8 weeks. Hyper-extension of ankle joints and eversion of hindlimbs at landing were also noted in the unloaded rats. These phenomena were not recovered at all. It was generally suggested that severe detrimental effects on the landing performance of rats are induced following 9-weeks of suspension. And some of the responses are irreversible.

Abdominal Muscles↗

PubMed2003

Palliative treatment of cancer anorexia with oral suspension of megestrol acetate.

Megestrol acetate (MA) is a progestational agent, currently known as one of the most effective appetite stimulants in patients suffering from cancer anorexia/cachexia syndrome. Oral suspension of this drug may be particularly useful in patients with far advanced disease, where taking larger amount of pills may lead to the decrease of patient compliance. The influence of oral MA suspension on quality of life and nutritional status was evaluated in 22 patients with far advanced cancer suffering from anorexia and more than 5 per cent weight loss, all beyond the scope of anticancer treatment. Most patients had lung or gastrointestinal cancer. QLQ-C30 questionnaire, visual analogue scale (VAS) for appetite, anthropometry, maximal handgrip strength and laboratory data were obtained before treatment and then after 2, 4, and 8 weeks of therapy. Despite of a known high mortality in this prognostically unfavorable group of patients (36% within two months in this study), overall quality of life after the daily dose of 480-840 mg of MA was improved in 63, 56, and 55% of patients remaining on therapy after 2, 4, and 8 weeks, respectively. Appetite was the most successfully influenced parameter with an improvement in VAS in 95% of cases after 2 weeks of therapy (p=0.0001). The drug was well tolerated by the great majority of patients. Oral suspension of megestrol acetate maybean effective palliative treatment for many patients with far advanced cancer suffering from anorexia/cachexia syndrome.

Administration, Oral↗

PubMed1962

Problems in standardization of turbidity determinations on bacterial suspensions.

The concentration of bacterial suspensions can be rapidly and conveniently determined by measuring the turbidity. Although turbidimetry offers advantages over the more laborious methods of weighing or counting, it is necessary to be aware of the possible sources of error. It is therefore advisable for every type of instrument used to specify, in terms of the International Opacity Reference Preparation, the turbidities of known suspensions of the organisms under study. Only bacterial suspensions having the same extinction coefficient can be adjusted to the same content of bacteria by means of the International Opacity Reference Preparation.

Bacteria↗

PubMed2003

[Comparative histomorphometric studies of shin bones of male and female rats following tail suspension].

In a 30-d experiment with tail-suspension of male and female rats histomorphometric studies were performed to compare impacts of deficient weight loading on the tibial spongy tissue. The 30-d suspension was found to slow down the body and adrenal mass gain irrespective of sex; however, this effect was more pronounced in male rats suggesting a greater stress to males as compared to females. Also, suspension caused tibial osteopenia in either of sexes. Decreases in the tibial spongy mass in suspended male and female rats were similar to control. At the same time, inhibition of the longitudinal bone growth attested by diminished height of the cartilaginous growth plate was more noticeable in males as compared with females. We attribute this observation to the reduction in testosterone production and a more violent stress reaction.

Adrenal Glands↗

PubMed2004

Effects of tail suspension on electrophysiological characteristics of muscle spindles in isolated rat soleus muscle.

OBJECTIVE: To study changes in electrophysiological characteristics of muscle spindles induced by simulated weightlessness in isolated rats soleus. METHOD: Weightlessness was simulated by tail-suspension in female rats. Using electro-physiological technique, the spontaneous discharge of muscle spindle and its response to ramp-and-hold stretch were observed in isolated soleus of 7 d, 14 d tail-suspended and control rats. RESULT: Soleus muscle spindles of rat manifest a sharp decrease in spontaneous discharge frequency and the response to ramp-and-hold stretch after 7 d tail-suspension. More significant changes were observed in rats after 14 d tail-suspension. CONCLUSION: Simulated weightlessness could induce time-related changes in electrophysiological characteristics of soleus muscle spindles in rat.

Animals↗

PubMedDate not supplied

[Adaptive responses of the secretory cardiomyocytes of the right atrium during simulation of the long-term and repeated gravity by antiorthostatic suspension of rats].

Reactive changes in right atrium cardiomyocytes during antiorthostatic tail suspension of rats commonly used to simulate low gravity have been studied by electron microscopy and morphometry. A 14 day suspension proved to increase contractile and secreting activities of cardiomyocytes. At the same time, signs of depleted activity are observed in some cells. Elongation of the experiment to 30 days leads to development of adaptive compensatory responses and increases their secreting capacity. A 30 day return to normal orthostatic position does not completely restores the structure and functioning of cardiomyocytes and leads to accumulation of internal secretion. A repeated 14 day suspension to a certain extent facilitates cardiomyocyte adaptation to altered conditions as compared to a single exposure; apparently, secretion release decreases while its production is activated.

Adaptation, Physiological↗

PubMedDate not supplied

Preparation of peanut butter suspension for determination of peanuts using enzyme-linked immunoassay kits.

Peanuts are one of the 8 most common allergenic foods and a large proportion of peanut-allergic individuals have severe reactions, some to minimal exposure. Specific protein constituents in the peanuts are the cause of the allergic reactions in sensitized individuals who ingest the peanuts. To avoid accidental ingestion of peanut-contaminated food, methods of analysis for the determination of the allergenic proteins in foods are important tools. Such methods could help identify foods inadvertently contaminated with peanuts, thereby reducing the incidence of allergic reactions to peanuts. Commercial immunoassay kits are available but need study for method performance, which requires reference materials for within- and between-laboratory validations. In this study, National Institute of Standards and Technology Standard Reference Material 2387 peanut butter was used. A polytron homogenizer was used to prepare a homogenous aqueous Peanut Butter suspension for the evaluation of method performance of some commercially available immunoassay kits such as Veratox for Peanut Allergen Test (Neogen Corp.), Ridascreen Peanut (R-Biopharm GmbH), and Bio-Kit Peanut Protein Assay Kit (Tepnel). Each gram of the aqueous peanut butter suspension contained 20 mg carboxymethylcellulose sodium salt, 643 microg peanut, 0.5 mg thimerosal, and 2.5 mg bovine serum albumin. The suspension was homogenous, stable, reproducible, and applicable for adding to ice cream, cookies, breakfast cereals, and chocolate for recovery studies at spike levels ranging from 12 to 90 microg/g.

Arachis↗

PubMed2004

Physical transformation of niclosamide solvates in pharmaceutical suspensions determined by DSC and TG analysis.

This study reports the preparation of four niclosamide solvates and the determination of the stability of the crystal forms in different suspension vehicles by DSC and TG analysis. Thermal analysis showed that the niclosamide solvates were extremely unstable in a PVP-vehicle and rapidly changed to monohydrated crystals. A suspension in propylene glycol was more stable and TG analysis showed that crystal transformation was less rapid. In this vehicle, the crystals transformed to the anhydrate, rather than the monohydrate, since the vehicle was non-aqueous. The TEG-hemisolvate was the most stable in suspension and offered the best possibility of commercial exploitation.

Algorithms↗

PubMed1992

Stability of flecainide acetate in an extemporaneously compounded oral suspension.

The stability of flecainide acetate in an oral diluent stored for 45 days under various conditions was studied. A suspension was prepared by triturating 100-mg tablets of flecainide acetate with a commercially available oral diluent. The final theoretical drug concentration was 5 mg/mL. The suspension was poured into 12 2-oz amber glass prescription bottles for a per-bottle volume of 60 mL. Three bottles were refrigerated at 5 degrees C and shaken before analysis, three were stored at room temperature and shaken, three were refrigerated and not shaken, and three were kept at room temperature and not shaken. On days 0, 15, 30, and 45, flecainide acetate concentrations were determined by stability-indicating high-performance liquid chromatography. The concentration of flecainide acetate in the sediment in each bottle was determined on day 46. On day 45, the mean flecainide acetate concentration for each group of bottles remained above 90% of the initial concentration. Mean +/- S.D. flecainide acetate concentrations in sediment ranged from 0.53 +/- 0.30 to 1.18 +/- 0.36 mg per gram. Eight of the 12 samples contained microbial growth on at least one of the test days. Flecainide acetate 5 mg/mL oral suspension was stable for up to 45 days under the conditions investigated.

Bacteria↗

PubMedDate not supplied

A simple and rapid method for purification of triamcinolone acetonide suspension for intravitreal injection.

Purification of triamcinolone acetonide suspension is important to avoid the potential toxic effects of the vehicle. The aim of this article is to describe a simple and rapid technique to remove the vehicle, instead of the long procedure described in the literature. Triamcinolone acetonide suspension was sedimented by density gradient centrifugation. In a few minutes, this new technique yielded a clear supernatant that was easily replaced by a nontoxic sterile solution. More prolonged procedures may not be convenient for unplanned treatments and may also contribute to a greater chance for contamination of the triamcinolone acetonide suspension.

Glucocorticoids↗

PubMedDate not supplied

Suspension made with amniotic membrane: clinical trial.

PURPOSE: To investigate if a suspension made with amniotic membrane could have a beneficial effect on ocular surface diseases. METHODS: In the Imola branch of the Eye Bank of Emilia Romagna, the authors prepared a suspension containing homogenized amniotic membrane previously conserved at -80 degrees Celsius. Subsequently, the authors gave this preparation to 21 patients: 8 had undergone lamellar keratoplasty, 4 had undergone penetrating keratoplasty, 2 had undergone photorefractive keratectomy with a delay of epithelialization, 3 had neurotrophic corneal ulcers, 2 had corneal burning, 1 had torpid corneal ulcer, and 1 had Sjogren syndrome. Each patient had been treated with conventional therapy for at least, 4 months without any clinical improvement. In this sample of eyes the authors evaluated the transparency and integrity of epithelium before and after the therapy by means of a fluorescein staining test, examining the area of epithelial defect as well as the phlogistic situation and the symptoms referred by patients. Nine eyes from this group of patients were studied by impression cytology before and after 3 months of use of suspension. The follow-up was 5 months of once-weekly visits. RESULTS: In all patients, after 15 to 30 days the corneas became negative to fluorescein staining test and the epithelium seemed more complete and regular, there was an evident decrease of phlogistic situation in the conjunctiva, and an improvement of symptoms was referred by patients. The situation was stable during the whole follow-up. No side effects were noted. The impression cytology repeated 3 months after the treatment showed a significant corneal recovery of the cytologic situation with an important decrease of CK19+ cells on the corneal surface. CONCLUSIONS: This new therapy, which is less traumatic than an implant of amniotic membrane, is safe, and can be repeated for a long period, could help patients with corneal superficial defects.

Amnion↗

PubMedDate not supplied

[Effect of two-week tail suspension on the reactivity of rat's cerebral vessels].

Reactivity of the cerebral vessels feeding two different brain regions was studied in rats after the hind limb unloading during two-wk tail-suspension. The basilar and middle cerebral arteries were isolated and perfused with a steady flow of the Krebs solution. Constriction responses to serotonin (10(8)-10(5) M) and high-K+ solution (100 mM) and dilatation responses to the beta-adrenoceptor agonist isoproterenol (10(8)-3 x 10(6) M) were evaluated. Tail suspension had no effect on the reactivity of the middle cerebral artery. The basilar artery reaction to K+ and isoproterenol remained unchanged compare to the control, whereas the reaction to serotonin was augmented significantly. Therefore, regional differences in the cerebral vessels reactivity were observed in rats after two weeks of tail suspension.

Adrenergic beta-Agonists↗

PubMed2006

Stochastic probability modeling to predict the environmental stability of nanoparticles in aqueous suspension.

The term "nanomaterial" describes a preparation in which the particle size is on the order of 10 to 100 nm in diameter. Such particles have the ability to form suspensions in fluid media such as air and water that can dramatically increase the environmental transport potential in comparision with like materials of larger particle sizes. Quantifying such transport requires an ability to predict the stability of such suspensions as to their tendency to aggregate or interact with other environmental constituents. In this paper, we present a method for predicting the magnitude and uncertainty associated with nanoparticle suspension stability. The critical buoyancy properties are predicted using the Boltzmann equation. The rates of aggregation are then predicted on the basis of molecular collision and adhesion coefficients. The progress of particle growth is simulated across all potential pathways probabalistically using the Gillespie model to characterize the uncertainty. Discussion is provided regarding potential environmental applications and further potential development in predicting particle behavior and effects on the environment.

Models, Theoretical↗

PubMed1990

[Determination of the dispersity of suspensions using photoelectric colorimeters of different makes].

Different conditions of measuring the suspension dispersity of photoelectric colorimeters of two brands,KFK-2 and FEK-56, result in distorted data: the dispersity index (DI) measured by KFK according to the method developed for FEK is inaccurate. The presence of 2 photoreceptors in the KFK apparatus, in contrast to the FEK one, results in elevated values of optic density (D) when the apparatus sensitivity is changed, starting from 590 nm wavelength (this fact is mentioned in the operation instructions) and eventually breaks the inversely proportional relationships between the D value and wavelength. DI estimation is based on the proportional relationships between wavelengths and D values obtained with a selected light filter pair. The wavelength selection mode had to be changed in the procedure of DI measurement by KFK-2 (or by KFK-MP) so that the light filter pair was placed in the same sensitivity zone; the distance between the cuvette and photo element was also changed (the cuvette with the sample was placed not in the cuvette holder but at a maximum distance from the photo element, closer to the source of light). Such modifications helped obtain compatible results of optic density measurements and DI values with photoelectric colorimeters of various brands. This is true only for suspensions rather than for transparent solutions, which fact is explained by the theory of light dispersion by suspension particles.

Colorimetry↗

PubMedDate not supplied

[Comparative study of Aujeszky's disease virus reproduction in a suspension of poultry embryonic cells and tissues (author's transl)].

Reproduction of Aueski disease virus in suspension cultures of trysinized cells and mechanically minced tissue of chick, duck and quail embryos was compared. The optimal conditions for cultivation of vaccine and virulent strains of virus in these systems were determined. The advantages and prospects of using suspension cultures of minced avian embryo tissue for preparation of virus materials with high biological activity and in large volumes in comparison with trypsinized cell suspensions were demonstrated.

Animals↗