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PubMed1985

Dynamic light scattering from dilute suspensions of thin discs and thin rods as limiting forms of cylinder, ellipsoid and ellipsoidal shell of revolution.

A previous formulation of the field correlation function G1(tau) of light quasielastically scattered from suspensions of rigid rods undergoing anisotropic translational as well as rotational diffusion (T. Maeda and S. Fujime, Macromolecules 17 (1984) 1157) was extended to the cases of suspensions of cylinders (length L and radius R), ellipsoids and ellipsoidal shells of revolution (x2/b2 + y2/b2 + z2/a2 = 1). The present formulation includes that for suspensions of rigid rods in the limit of KR 1 or in the limit of b/a 1 and Kb 1 (an extremely prolate ellipsoid), and also that for suspensions of discs in the limit of KL 1 or in the limit of b/a 1 and Ka 1 (an extremely oblate ellipsoid), where K is the length of the scattering vector. Explicit forms of G1(tau), of the first cumulant Gamma of G1(tau) and of the dynamic form factors will be given, and numerical methods suitable for computation of dynamic form factors will be discussed. The present results can be applied to the analysis of experimental data for dilute suspensions of thin rods and thin discs. When the situation is favorable, our method can provide transport coefficients D1, D3, and Theta from dynamic light-scattering data only, where D(1) and D(3) are, respectively, the translational diffusion coefficients parallel with the x (y) and z axes, and Theta the rotational diffusion coefficient around the x (y) axis.

Journal Article↗
PubMed1996

Continuous monitoring of mitochondrial membrane potential in hepatocyte cell suspensions.

We report a simple fluorometric method for the continuous monitoring of mitochondrial membrane potential and cell viability in suspensions of hepatocytes exposed in vitro to cytotoxic agents. Suspensions of freshly isolated hepatocytes (10(6) cells/mL) preloaded with rhodamine 123 (Rh 123, 100 mumol/L) are transferred to a thermostatically controlled mixed cuvette to which the desired cytotoxic agent is added. Rh 123 is a cationic fluorophore that is actively accumulated by cells in direct proportion to the mitochondrial membrane potential. Cell viability was estimated by monitoring propidium iodide (PI) fluorescence. Exposure of cell suspensions to the mitochondrial uncoupling agent FCCP caused an immediate and titratable increase in Rh 123 fluorescence. Subsequent treatment with digitonin did not change Rh 123 fluorescence, suggeseting that Rh 123 equilibrates rapidly across the intact cell membrane. Likewise, treatment of hepatocyte suspensions with inhibitors of mitochondrial respiration (rotenone, cyanide, or menadione) caused an immediate increase in Rh 123 fluorescence. This was accompanied by a progressive increase in PI fluorescence, suggesting a causal relationship between mitochondrial depolarization and cell injury. In contrast, 1,4-benzoquinone caused a time-dependent and linear increase in PI fluorescence that paralleled changes in Rh 123 fluorescence. Comparing the time courses for changes in PI and Rh 123 fluorescence suggests that for benzoquinone, the depolarization of the mitochondria is a consequence rather than a cause of the cell injury. This modified procedure provides a simple and specific technique for continuously monitoring mitochondrial membrane potential and cell viability in suspensions of freshly isolated hepatocytes. The advantage is that there is no need to separate cells from the incubation medium, making it possible to record real-time changes in mitochondrial membrane potential and cell viability throughout the in vitro exposure period.

Animals↗
PubMed2006

Sensory nerve injury after uterosacral ligament suspension.

OBJECTIVE: Uterosacral ligament suspension is a technique that is performed commonly to suspend the prolapsed vaginal apex. This case series describes our experience with the clinical evaluation and management of lower extremity sensory nerve symptoms after uterosacral ligament suspension. STUDY DESIGN: Hospital and office medical records from our 2 institutions were reviewed from January 2002 to August 2005, and all women who underwent uterosacral ligament suspension through a vaginal approach were identified. Women with symptoms of buttock and posterior thigh pain during the 6-week postoperative period were identified, and detailed clinical information was abstracted from the charts. RESULTS: From 182 uterosacral ligament suspension procedures, 7 women were identified. The age range was 42 to 70 years. Concurrent procedures included 6 vaginal hysterectomies, 5 anterior repairs, 4 posterior repairs, 2 slings, and 1 bilateral salpingo-oophorectomy. Within 24 hours of the surgical procedure, all the women experienced similar, substantial sharp buttock pain and numbness that radiated down the center of the posterior thigh to the popliteal fossa in 1 or both lower extremities. The ipsilateral uterosacral ligament suture was removed within 2 days of the procedure in 3 women who had immediate subjective reduction in their pain and complete resolution of pain by 6 weeks. The remaining 4 women were treated with gabapentin and narcotics. Three women had resolution of the pain by 12 to 14 weeks after the operation, and the last woman's pain resolved gradually by 6 months. CONCLUSION: Women who undergo uterosacral ligament suspension are at risk of postoperative pain and numbness in a S2-4 distribution. These symptoms appear to be related to the placement of uterosacral ligament sutures and may be relieved either by prompt removal of the ipsilateral uterosacral ligament suture or with prolonged medical therapy.

Adnexa Uteri↗
PubMed2005

Labile and non-labile desorption rate constants for 33 PCB congeners from lake sediment suspensions.

Lake sediments contaminated with polychlorinated biphenyls (PCBs) were purged using a gas stripping technique to estimate desorption rate constants. Desorption profiles and modeling of the data clearly show a two-step release of PCBs from sediment suspensions that can be described as a labile (fast) release followed by a non-labile (slow) release. Data are summarized by labile and non-labile rate constants and by mass in each phase as a function of suspended solids concentration for twelve pure congeners and nine co-eluting data sets (twenty-one chromatograph peaks total). Labile desorption rate constants range from 113 days(-1) to 1.43 days(-1) for the 100 mg/l sediment suspension, from 67.7 days(-1) to 2.45 days(-1) for the 1000 mg/l sediment suspension, and from 8.41 days(-1) to 0.946 days(-1) for the 5000 mg/l sediment suspension. Labile rate constants consistently decreased with increasing suspended solids, and, in general, decreased with increasing degree of chlorination (reflected in increasing retention time in the chromatogram). No consistent trend was observed for the non-labile rate constants with suspended solids concentration or degree of chlorination. The average non-labile rate constant for the PCB congeners studied here was 0.154 days(-1) (s.d.=0.158; n=63). The distribution between the labile and non-labile phases also failed to indicate dependence on suspended solids concentration, chlorine substitution pattern, or molecular weight of the congener, although the data from the 5000 mg/l suspension consistently contained less labile components. The average distributions (n=63) were 60.1% in the labile phase and 39.9% in the non-labile phase.

Adsorption↗
PubMed2004

Flocculation of cellular suspensions by polyelectrolytes.

The regularities, kinetics and mechanisms of flocculation of Escherichia coli and B. thuringiensis var. israelensis (Bti) cellular suspensions by water-soluble polymers-and first of all cationic polyelectrolytes of different charge density and stiffness of the macromolecule chain have been investigated. The effect of the focculant dose and nature, its charge density, the hydrophobic-hydrophilic balance in macromolecule, the suspension concentration, the mode of adding the reagent, the pH and the medium composition on the degree of aggregation of cells both in perikinetic regime and in a flowing system is considered. It has been shown that the main laws of microorganism's suspension flocculation are the same as the laws of flocculation of inorganic dispersions but at the same time the first process is much more complicated because the cell-flocculant interactions are strongly affected by products of cell metabolism, components of the culture liquor, pH value, electrolyte content as well as by the changing structure of the cell surface. On the basis of complex measurements of polymer adsorption and its effect on the electrokinetic potential and degree of aggregation of cells, a conclusion is made that the aggregation of E. coli cells by flexible polyelectrolytes like polydiethylaminoethylmetacrylate and its copolymers with acrylic acid, acrylamide and vinylpyrrolidone is due to charge neutralization, while the flocculation in the presence of rigid-chain chitosan and its derivatives is caused mainly by "bridging" between cells via adsorbed macromolecules. Extraction of cells from suspension can be enhanced by combination of electroflotation and flocculation by cationic polyelectrolytes. It has been shown that dilute suspensions of Bti bacteria can be effectively flocculated and concentrated using different cationic and anionic polyelectrolytes that is necessary for its formulation and use as anti-mosquito agent.

Bacillus thuringiensis↗
PubMed2004

Comparison of the pharmacokinetics of lansoprazole 15- and 30-mg sachets for suspension versus intact capsules.

OBJECTIVE: The pharmacokinetic profiles of single doses of lansoprazole 15- and 30-mg sachets for suspension were compared with those of corresponding doses of lansoprazole oral capsules. METHODS: Healthy adult male and female subjects were randomized (1:1 ratio) into 2 Phase 1, open-label, single-dose, 2-sequence, 2-period complete crossover studies. In the first study, each subject received 1 lansoprazole 15-mg sachet mixed with water and 1 lansoprazole 15-mg oral capsule; in the second study, each subject received 1 lansoprazole 30-mg sachet mixed with water and 1 lansoprazole 30-mg oral capsule. Administration of the 2 formulations was separated by a washout period of > or =7 days. Blood samples were collected before and after each administration to assess the pharmacokinetic parameters of lansoprazole and bioequivalence between suspension and capsule. RESULTS: Thirty-six subjects (19 males, 17 females) with a mean (SD) age of 32.0 (9.6) years and mean (SD) body weight of 68.6 (10.5) kg received lansoprazole 15 mg. Thirty-six subjects (22 males, 14 females) with a mean (SD) age of 38.0 (8.3) years and mean (SD) body weight of 75.1 (9.7) kg received lansoprazole 30 mg. The pharmacokinetic parameters of the 15- and 30-mg lansoprazole sachets for suspension were similar to those of the corresponding doses of the oral capsules. The mean (SD) values for C(max) and AUC from time 0 to infinity (AUC(0-infinity) for the lansoprazole 15-mg sachet (591.9 [242.3] ng/mL and 1614 [2065] ng.h/mL, respectively) did not differ significantly from those for the lansoprazole 15-mg capsules (578.6 [275.2] ng/mL and 1620 [2290] ng.h/mL, respectively). These parameters also did not differ significantly between the lansoprazole 30-mg sachet and 30-mg capsule: mean (SD) C(max), 1103 (428.3) and 1077 (465.6) ng/mL, respectively; mean (SD) AUC(0-infinity), 2655 (1338) and 2669 (1311) ng.h/mL, respectively. The 90% Cls for C(max) and AUC(0-infinity) ratios were contained within the 0.80 to 1.25 equivalence range, supporting bioequivalence. CONCLUSIONS: These findings suggest that the 15- and 30-mg lansoprazole sachets for suspension are bioequivalent to the corresponding doses of oral capsules. The sachet for suspension may provide an alternative route of administration to patients who have difficulty swallowing solid oral formulations.

2-Pyridinylmethylsulfinylbenzimidazoles↗
PubMed2004

Experimental designed optimisation and stability evaluation of dry suspensions with artemisinin derivatives for paediatric use.

There is a great need for oral anti-malaria preparations especially for small children, which are easy to administer and keep their stability under tropical conditions. The purpose of this work was therefore to develop a dry suspension, containing one of the artemisinin derivatives, namely artesunate, artemether and dihydroartemisinin using fast wetting suspending agents, i.e. xanthan gum and Avicel CL611. For the optimisation of these two variables, namely the suspending agent's content, a Doehlert design was applied. Via preliminary tests on sedimentation behaviour, the limits of both products were determined, respectively 0.1-0.4% (w/v) and 1.0-2.5% (w/v). As responses, sedimentation as a function of time, viscosity and price of the suspension, were evaluated. The stability tests of the reconstituted suspensions showed bad results for artesunate, even when the pH was adapted. In contrast, dihydroartemisinin showed only 10% degradation within 10 days and artemether was stable at least 21 days. Practically the last one was able to foresee a chemically and physically stable suspension at least during the administration period (5 to 7 days) and was therefore selected for further optimisation concerning taste and appearance. Based on the results of selection tests for the colourant, sweetener and taste masking agent, the following composition was proposed for a suitable dry powder with artemether (AM) as active compound to prepare 100 ml reconstituted suspension: AM 300 mg, Avicel CL611 2 g, xanthan gum 200 mg, crystalline saccharose 35 g, citric acid monohydrate 150 mg, Nipagine 80 mg, Nipasol 20 mg, sodium saccharinate 250 mg, tutti-frutti 250 mg and Sunset yellow 10 mg.

Adult↗
PubMed2004

Measuring the electrophoretic mobility of concentrated suspensions in nonaqueous media.

We present a new method of measuring the electrophoretic mobility of a particle in a concentrated suspension. The method is used to measure the electrophoretic mobility of PMMA particles (diameter 10 microm) suspended in a mixture of liquid hydrocarbons. The particle volume fraction of the suspension is varied from 0 up to 0.30 and the resulting variation of the electrophoretic mobility is discussed. The suspending liquid is such that its refractive index is very close to that of the particles. Thus the suspension is almost transparent and it is possible to follow through a microscope the motion of one particle. The suspension is subjected to a low-frequency electric field (0.5 Hz). The cell containing the suspension is mounted on a piezoelectric crystal. The displacement that compensates for the particle motion (when the particle image is steady) is determined.

Journal Article↗
PubMed2004

Aggregation behavior of single-walled carbon nanotubes in dilute aqueous suspension.

The aggregation behavior of colloidal single-walled carbon nanotubes (SWNT) in dilute aqueous suspensions was investigated using a novel light scattering measurement technique. The aggregation of SWNT in three suspensions was examined: (1) nanotubes after acid treatment; (2) as-received nanotubes stabilized by a nonionic surfactant; and (3) acid-treated nanotubes with nonionic surfactant. Continuous light scattering measurements of the SWNT suspensions (probing the 38-436 nm length scale) made over two weeks showed that the nanotubes in each sample formed networks with fractal-like structures. The as-received nanotubes were stable over the measurement period, while the acid-treated nanotube suspension showed greater dispersion variability over time, yielding looser structures at large length scales and more compact structures at smaller length scales. The addition of surfactant to the acid-treated suspension significantly enhanced nanotube dispersion.

Journal Article↗
PubMed2005

Adsorption of poly(acrylic acid) onto the surface of titanium dioxide and the colloidal stability of aqueous suspension.

The adsorption of poly(acrylic acid) (PAA) in aqueous suspension onto the surface of TiO(2) nanoparticles was investigated. FTIR spectroscopic data provided evidence in support of hydrogen bonding and chemical interaction in the case of the PAA-TiO(2) system. Adsorption isotherms demonstrated that part of the PAA initially added to the suspension was adsorbed onto the TiO(2) surface, after which there was a gradual attainment of an adsorption plateau. The adsorption density of PAA was found to increase with an increase of PAA molecular weight, while it decreased with an increase of pH. The thickness of the PAA adsorption layer was calculated based on measurements of suspension viscosities in the absence and presence of PAA. It was shown that the thickness of the adsorption layer increased with the increase of pH, PAA molecular weight, and its concentration. The surface charge density, the diffuse charge density, and the zeta potential of TiO(2) varied distinctly after PAA adsorption. The shift of pH(iep) toward a lower pH value was observed in the presence of PAA. PAA was found to stabilize the suspension of TiO(2) nanoparticles through electrosteric repulsion. The influence of factors such as PAA molecular weight and its concentration on the colloidal stability of the aqueous suspension was also investigated.

Journal Article↗
PubMed2006

Characterization of concentrated colloidal ceramics suspension: a new approach.

The dispersion behavior of a concentrated ceramic suspension (Al(2)O(3)) has been investigated in terms of capillary suction time (CST) with varying solids concentration both in the absence as well as in the presence of dispersant (APC). The CST value is found to be the lowest at the pH(iep) whereas it increases as the pH is changed either to the acid side or alkaline side due to the repulsive forces acting among the neighboring particles keeping them in more dispersed state. It has been further observed that the CST value increases with increasing concentration of solids in the suspension. The dispersability of the suspension has been quantified in terms of dispersion ratio (DR). The higher the dispersion ratio of a particular system above unity, the better is the dispersability and vice versa. Further, quantification of dispersion stability by the CST technique is found to be useful and practical for optimization of different parameters concerning suspension stability. A correlation is found among the CST, zeta potential, colloidal stability, and maximum solids loading. It has been finally concluded that the CST method could be potentially employed as a quantitative and diagnostic technique for characterizing concentrated ceramic suspension.

Ceramics↗
PubMed2006

A novel method for preparing and characterizing alcoholic EPD suspensions.

Ceramic suspensions composed of alumina and mixtures of alumina and zirconia powders in ethyl alcohol were prepared. A solution of citric acid and triethylamine was used as dispersant. The citric acid, which usually is used as dispersant in water alumina suspensions, gave excellent results in ethyl alcohol also if it was used in conjunction with triethylamine. A novel method consisting of combined measurements of grain size, zeta potential, and transmittance was optimized to study the dispersion and stability properties of the ceramic suspensions; by using this method the optimal dispersant amount was determined. The suspensions based on alumina and alumina-zirconia powders were used to coat stainless steel plates by electrophoretic deposition (EPD); the optimal composition of suspensions and the used EPD parameters made it possible to obtain coatings with uniform thickness and composition.

Journal Article↗
PubMed2004

Human tonsillar tissue block cultures differ from autologous tonsillar cell suspension cultures in lymphocyte subset activation and cytokine gene expression.

Lymphoid tissues cultured either as tissue blocks or as cell suspensions are used to study the behaviour of immune cells within their habitat. The preservation of tissue structures in tissue blocks, which is considered to be a major advantage, has been poorly defined. We characterised the morphological evolution of tissue cultures from human palatine tonsils and compared their lymphocyte subsets and the constitutive cytokine gene expression to those in autologous tonsillar single-cell suspension cultures over time, and after adding cyclosporin A (CsA) to mimic the situation in individuals treated with immunosuppressive drugs. Density and morphology of follicles were conserved up to 4 days, during which tissue cultures exhibited similar cell viability as suspension cultures, but a significantly less frequent increase of CD95 expression in T cells, smaller variation of the proportion of CD4(+) cells and better CD21(+)/CD23(-) B-cell survival. Treatment with cyclosporin A at higher concentrations resulted in superior histologic preservation of lymphoid tissue structures and seemed to further prevent the expression of CD95 by CD3(+) cells and the activation in tissue culture of CD21(+) cells. Constitutive gene expression levels of the stromal cytokines interleukin (IL)-1beta and interleukin-6 in tissue culture were significantly higher than those in suspension cultures. These results suggest that tonsillar tissue cultures preserve their structure only for a limited time, during which they more closely reflect processes in vivo, including a state of iatrogenic immunosuppression, than do their cell suspension counterparts.

Antigens, CD↗
PubMedDate not supplied

A randomized comparison of vesicourethral function after laparoscopic hysterectomy with and without vaginal cuff suspension.

STUDY OBJECTIVE: To compare vesicourethral function following laparoscopic hysterectomy (LH) with and without vaginal cuff suspension. DESIGN: Prospective study (Canadian Task Force classification I). SETTING: Tertiary teaching hospital. PATIENTS: Sixty-eight women scheduled for LH randomly assigned to either LH without vaginal cuff suspension (LH group; n = 36) or LH with suspension (LHS group; n = 32). INTERVENTION: All subjects received urinalysis, pelvic examination, Q-tip test, introital ultrasonography, and a urinary questionnaire before and 6 months after surgery. MEASUREMENTS AND MAIN RESULTS: The prevalence of stress urinary incontinence (SUI) decreased significantly from 46.9% (n = 15) preoperatively to 18.8% (n = 6) postoperatively in the LHS group (p = .022), but this was not so in the LH group. Similarly, the mean straining urethral angle and the number of women exhibiting bladder neck (BN) hypermobility significantly decreased after surgery in only the LHS group (p <.05; p <.01, respectively). During straining, the postoperative position of the BN localized more dorsally (p <.01), and its ventral mobility decreased significantly (p <.01) in the LH group. In the LHS group, significant postoperative reduction was found in both ventral and caudal movements of the BN during stress (p <.01), causing a more cranial and dorsal position of the BN (p <.01). CONCLUSION: Laparoscopic hysterectomy with cuff suspension strengthens the traction effect on the endopelvic fascia, reducing both BN mobility during stress and the chance of SUI. However, simply performing a cuff suspension is not adequate for the treatment of severe SUI.

Adult↗
PubMed2006

Preparation of microbubble suspensions by co-axial electrohydrodynamic atomization.

In this paper we report a novel method, based on co-axial electrohydrodynamic jetting, for the preparation of microbubble suspensions containing bubbles <10 microm in size and having a narrow size distribution. No selective filtration is necessary and the suspensions are produced directly by the process. To demonstrate the method, glycerol was used as the liquid medium, flowing in the outer needle of the co-axial twin needle arrangement and undergoing electrohydrodynamic atomization in the stable cone-jet mode while air flowed through the inner needle at the same time. At zero applied voltage a hollow stream of liquid flowed from the outer needle. When the applied voltage was increased, eventually the hollow stream became a stable cone-jet and emitted a microthread of bubbles, which were collected in a container of glycerol to obtain microbubble suspensions. The size of the microbubbles was measured via optical microscopy and laser diffractometry. Several microbubble suspensions were prepared and characterised and the size distribution was found to be critically dependent on the ratio (n) of flow rates of liquid/air and, in particular the flow rate of the air. At n=1.5, with the flow rate of air set at approximately 1.7 microl/s, a microbubble suspension containing bubbles in the size range 2-8 microm was obtained.

Colloids↗
PubMed2001

The osmolality of the cell suspension regulates phycobilisome-to-photosystem I excitation transfers in cyanobacteria.

The chlorophyll a (Chla) fluorescence of cyanobacteria, which at physiological temperature originates from photosystem (PS) II holochromes, is suppressed in hyperosmotic suspension, and enhanced in hypo-osmotic suspension (G.C. Papageorgiou, A. Alygizaki-Zorba, Biochim. Biophys. Acta 1335 (1997) 1-4). We investigated the mechanism of this phenomenon by comparing Synechococcus sp. PCC 7942 cells that had been treated with N-ethylmaleimide (NEM) in order to inhibit electronic excitation transfers from phycobilisomes (PBS) to Chlas of PSI (A.N. Glazer, Y.M. Gindt, C.F. Chan, K. Sauer, Photosynth. Res. 40 (1994) 167-173) with untreated control cells. The NEM-treated cells were indistinguishable from the control cells with regard to PSII-dependent oxygen evolution, reduction of post-PSII oxidants, and osmotically induced volume changes, but differed in the following properties: (i) they could not photoreduce post-PSI electron acceptors; (ii) they diverted more PBS excitation to PSII; (iii) the rise of Chla fluorescence upon light acclimation of darkened (state 2) cells was smaller; and (iv) the Chla fluorescence of light-acclimated (state 1) cells was insensitive to the cell suspension osmolality. These properties suggest that osmolality regulates the core-mediated excitation coupling between PBS and PSI, possibly by influencing mutual orientation and/or distance between core holochromes (ApcE, ApcD) and PSI holochromes. Thus, in hyper-osmotic suspension, PBS deliver more excitation to PSI (hence less to PSII); in hypo-osmotic cell suspension they deliver less excitation to PSI (hence more to PSII).

Bacterial Proteins↗
PubMed1977

Turbulent flow of red cells in dilute suspensions. Effect on kinetics of O2 uptake.

The turbulent flow properties of dilute (0.06% by volume) suspensions of human red blood cells in 4-mm-bore glass tubing were estimated by laser anemometry. The flow properties of the dilute red cell suspension were similar to those of a dilute suspension of polystyrene spheres (0.5 micron diameter) in isotonic NaCl solution. Flow was found to be laminar when the Reynolds number was below 2,000, transitional in the range of Reynolds numbers from 2,000 to 3,000, and fully turbulent above Reynolds number 3,000. These results differ from previous studies of more concentrated red cell suspensions. The length scales of the turbulence were also estimated: at a Reynolds number near 4,000 the macroscale is about 1.25 mm, the Taylor microscale is about 0.85 mm, and the Kolmogoroff scale is near 0.075 mm. The results are discussed in relation to previous measurements of the rate of oxygen uptake by dilute red cell suspensions in the flow-type rapid reaction apparatus. Our results suggest that under the conditions of most of these oxygen uptake measurements, the turbulent flow is characterized by eddies about 1 mm across, mixing with each other on a time scale of about 45 ms. Since most of the reported oxygen uptake measurements involve a similar time scale, it is possible that an effective "unstirred layer" influenced the reported rate of oxygen uptake.

Blood Flow Velocity↗
PubMed2001

Group housing of mice increases immobility and antidepressant sensitivity in the forced swim and tail suspension tests.

The forced swim test and tail suspension test are often used in laboratory practice to identify compounds that possess antidepressant-like activity. This experiment was conducted to determine whether housing conditions per se influence the response of mice in these antidepressant screening procedures. Male NIH Swiss mice were housed individually or in groups (five per cage) for 8 weeks prior to testing. After 8 weeks, the animals were exposed to the forced swim and tail-suspension tests. Group housed mice displayed high levels of immobility in the forced swim and tail suspension tests. Desipramine injection 60 min prior testing, in doses 7.5 and 15 mg/kg, produced significant reductions in the immobility time in forced swimming and tail suspension tests. Individually housed mice, when exposed to these tests, displayed lower levels of immobility with a magnitude comparable to the effect of desipramine in group housed mice. Desipramine given to individually housed mice did not reduce the duration of immobility either in the forced swim test or in the tail suspension test. These results indicate that both tests are sensitive to housing conditions. This observation suggests that long lasting group housing may be critical to the behavioral response in these preclinical screening procedures in mice.

Animals↗