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At least 649 records · Page 36Linked to original sources
PubMed1993

A prospective study to evaluate the efficacy of modified swim-up preparation for male sex selection.

A previously published study reporting the use of a modified swim-up technique for sperm preparation prior to insemination which resulted in a high percentage of male births has been criticized for its lack of controls. The present prospective study was initiated to investigate further the efficacy of modified swim-up preparation for male sex-selection when applied in a properly defined control group. Our results showed that the proportion of males born in singleton pregnancies was approximately 50% in the group inseminated following sperm preparation with Percoll and in the control group with no sperm preparation compared with 88.5% in the group treated with the modified method of swim-up sperm preparation prior to insemination. This high rate of males in the group treated with modified swim-up was also observed in singleton pregnancies of women taking ovulation inducing drugs (primarily clomiphene citrate). This contrasts with previous publications in which a higher rate of females was found in clomiphene citrate patients using the albumin separation technique. How the mechanism of the swim-up procedure may result in a high male birth rate remains unclear. A high percentage of y enriched semen was found using fluorochrome quinacrine mustard staining but this procedure may falsely stain autosomal chromosomes. If analysis using sensitive DNA probes fails to confirm the y enrichment of the spermatozoa, one must hypothesize that the modified swim-up procedure damages the x-spermatozoa.

Female↗
PubMed1992

Modulation of swimming rhythmicity by 5-hydroxytryptamine during post-embryonic development in Xenopus laevis.

During the first 24 h of post-embryonic development in Xenopus laevis, a rapid change in the neural activity underlying swimming occurs in which the duration of ventral root discharge on each cycle increases from a single compound impulse to discrete bursts of activity. Moreover, this change in motor output progresses rostrocaudally, suggesting that it could result from the influence of a descending neural pathway upon the spinal rhythm-generating circuitry during early post-embryonic development. To begin to examine whether serotonergic neurons of brainstem raphe nuclei might have a role in this swimming development, we have studied the effects of 5-hydroxytryptamine (5HT) on fictive swimming in embryonic and larval animals. As previously demonstrated for other vertebrate locomotor rhythms, we find that bath-applied 5HT enhances the duration of motor activity on each cycle of larval fictive swimming. In addition, our results show that the sensitivity of the swimming rhythm to exogenous 5HT follows a strict rostrocaudal gradient. In young embryos (stages 32-36) 5HT does not affect the duration of ventral root impulses per cycle; by the time of hatching (stage 37/38), rostral but not caudal discharge is enhanced, and by stage 42 (24 h post-hatching) 5HT can increase motor burst durations along most of the length of the animal. These reversible changes induced by bath-applied 5HT closely resemble the normal rostrocaudal development of burst discharge during swimming in animals some 12 h older.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMedDate not supplied

Swim-down separation of progressively motile sperm from poor quality human semen by the modified funnel procedure.

The simultaneous swimming up and down from identical semen specimens suggested that the separation efficiency of progressively motile sperm by the swim-down method was superior to that of the swim-up method. The swimming down was performed in a small plastic funnel, the bottom of which was plugged with a 2.5 ml disposable syringe. In this funnel, 2.0 ml of 70% Percoll was poured and then the sperm resuspension was overlaid. After 1 h, progressively motile sperm penetrating into the lower part of Percoll layer (1.6 ml) was collected in the syringe. The technical strategies to yield higher density of progressively motile sperm were found to be centrifugal concentration of the sperm from whole ejaculate prior to the swimming down, and subsequent re-centrifugation of the separated sperm after the swimming down. Oligo-asthenozoospermic semen (22 +/- 4.4 x 10(6) ml1, 5.5 +/- 4.4% motility, n = 8) was processed by the present method, yielding sperm qualities of 32 +/- 19 x 10(6) ml1, 74 +/- 14% in the final preparations. Overall improvement in fertility index (sperm density ml1 x motility % x 10(8)) reached 27-folds on average.

Cell Separation↗
PubMed2005

Comparative study on density gradients and swim-up preparation techniques utilizing neat and cryopreserved spermatozoa.

AIM: To 1) compare post-wash and post-thaw parameters of sperm processed with PureSperm density gradient technique and swim-up method; and 2) test the efficacy of two commonly available density gradient media PureSperm and ISolate. METHODS: This prospective study used semen specimens from 22 patients. Specimens from nine patients were processed by both PureSperm density gradient and swim-up method. These specimens were then cryopreserved. Thirteen specimens were processed by both PureSperm (40 % and 80 %) and Isolate (50 % and 90 %) double density gradient techniques. The two fractions processed by both PureSperm and swim-up were analyzed for post-wash sperm characteristics. Post-thaw analysis was done after 24 hours. Sperm fractions obtained after processing with PureSperm and ISolate were compared for post-wash sperm characteristics and ROS levels. RESULTS: Specimens prepared with PureSperm had significantly higher median total motile sperm counts (TMSC) (32.2 x 10(6) vs. 17.6 x 10(6)), recovery rates (69.2 % vs. 50.0 %), and longevity at 4 hours (83.0 % vs. 55.0 %) compared to specimen prepared by swim-up. Post-thaw specimens also had a higher recovery and longevity at 4 hours with PureSperm as compared to the swim-up. Semen specimens processed by PureSperm had significantly higher total sperm count, TMSC, and percentage recovery rates (30.0 % vs. 19.7 %) than ISolate. CONCLUSION: Semen quality is better preserved in fresh and cryopreserved semen prepared with PureSperm density gradient compared to swim-up. A significant enrichment of sperm is observed with PureSperm compared to ISolate. Higher recovery rates of mature motile sperm obtained after PureSperm sperm preparation may be beneficial for successful ART.

Cell Separation↗
PubMed1999

Roles of chemosensory pathways in transient changes in swimming speed of Rhodobacter sphaeroides induced by changes in photosynthetic electron transport.

The response of free-swimming Rhodobacter sphaeroides to increases and decreases in the intensity of light of different wavelengths was analyzed. There was a transient (1 to 2 s) increase in swimming speed in response to an increase in light intensity, and there was a similar transient stop when the light intensity decreased. Measurement of changes in membrane potential and the use of electron transport inhibitors showed that the transient increase in swimming speed, following an increase in light intensity, and the stop following its decrease were the result of changes in photosynthetic electron transport. R. sphaeroides has two operons coding for multiple homologs of the enteric chemosensory genes. Mutants in the first chemosensory operon showed wild-type photoresponses. Mutants with the cheA gene of the second operon (cheAII) deleted, either with or without the first operon present, showed inverted photoresponses, with free-swimming cells stopping on an increase in light intensity and increasing swimming speed on a decrease. These mutants also lacked adaptation. Transposon mutants with mutations in cheAII, which also reduced expression of downstream genes, however, showed no photoresponses. These results show that (i) free-swimming cells respond to both an increase and a decrease in light intensity (tethered cells only show the stopping on a step down in light intensity), (ii) the signal comes from photosynthetic electron transfer, and (iii) the signal is primarily channelled through the second chemosensory pathway. The different responses shown by the cheAII deletion and insertion mutants suggest that CheWII is required for photoresponses, and a third sensory pathway can substitute for CheAII as long as CheWII is present. The inverted response suggests that transducers are involved in photoresponses as well as chemotactic responses.

Antimycin A↗
PubMed1994

UNDERWATER SWIMMING AT LOW ENERGETIC COST BY PYGOSCELID PENGUINS

Energetic requirements of under-water swimming in pygoscelid penguins were studied in Antarctica, using respirometry together with a 21 m long swim canal and externally attached devices recording the swimming speed and dive duration of unrestrained animals. Field measurements were compared with measurements of the hydrodynamic properties of an Adelie penguin model in a circulating water tank. Minimium transport costs during underwater swimming in Adelie (Pygoscelis adeliae), chinstrap (P. antarctica) and gentoo (P. papua) penguins averaged 4.9, 3.7 and 7.6 J kg-1 m-1, respectively, at their preferred swimming speeds of 2.2, 2.4 and 1.8 m s-1, allowing the birds to dive aerobically for 110, 130 and 93 s, respectively. From the swim canal measurements, we calculated a drag coefficient (CD) of 0.0368 for a typical Adelie penguin at 2.2 m s-1. This value is significantly lower than the CD of 0.04 of an ideal spindle and the CD of 0.0496 measured on the model in the laboratory. The reasons for this difference are discussed.

Journal Article↗
PubMed1995

Serotonergic modulation of swimming speed in the pteropod mollusc Clione limacina. II. Peripheral modulatory neurons.

A symmetrical cluster of serotonin-immunoreactive neurons in the pedal ganglia of Clione limacina has been described morphologically and physiologically. At least five of the cluster neurons send axons to the ipsilateral wing that branch throughout the entire wing area. Activation of these cells did not produce a motor effect in non-swimming preparations, but did enhance contractility in swimming preparations. Activity in the pedal neurons did not produce detectable central effects as neither swim interneuron nor swim motor neuron activities were altered. Most notable was a lack of a change in swim frequency, a characteristic of swim acceleration. Activity in the pedal neurons did enhance the size of muscle junctional potentials and spike-like responses, but only in slow-twitch muscles. The peripheral modulatory effect was blocked by the serotonin antagonist mianserin.

Animals↗
PubMed1995

Neither the 5-HT1A- nor the 5-HT2-receptor subtype mediates the effect of fluvoxamine, a selective serotonin reuptake inhibitor, on forced-swimming-induced immobility in mice.

The effect of fluvoxamine, a selective serotonin (5-HT) reuptake inhibitor, was studied in the forced-swimming test, a model of depression, in mice. Fluvoxamine at 60 mg/kg, p.o. significantly decreased the immobility time in the forced-swimming test. A similar effect was observed by the selective norepinephrine reuptake inhibitor desipramine at the same dose. Furthermore, the suppression of immobility time was slightly potentiated by repeated administration of fluvoxamine, and a significant effect was observed at 30 mg/kg, p.o. The effect of fluvoxamine on forced-swimming was unaffected by the 5-HT2 antagonist ritanserin. On the other hand, the 5-HT1A antagonist NAN-190 (1-(2-methoxyphenyl)-4-[4-(2-phthalimido)butyl] piperazine) potentiated the effect of fluvoxamine on forced-swimming. It is expected, however, that a 5-HT1A antagonist should antagonize the effect of fluvoxamine when 5-HT1A mediates the suppressive effect of fluvoxamine on the immobility time in forced-swimming. From these results, neither the 5-HT1A- nor the 5-HT2-receptor subtype is involved in the suppressive effect of fluvoxamine on the immobility associated with forced-swimming.

Analysis of Variance↗
PubMed2005

Difference in bacterial motion between forward and backward swimming caused by the wall effect.

A bacterial cell that has a single polar flagellum alternately repeats forward swimming, in which the flagellum pushes the cell body, and backward swimming, in which the flagellum pulls the cell body. We have reported that the backward swimming speeds of Vibrio alginolyticus are on average greater than the forward swimming speeds. In this study, we quantitatively measured the shape of the trajectory as well as the swimming speed. The trajectory shape in the forward mode was almost straight, whereas that in the backward mode was curved. The same parameters were measured at different distances from a surface. The difference in the motion characteristics between swimming modes was significant when a cell swam near a surface. In contrast, the difference was indistinguishable when a cell swam >60 microm away from any surfaces. In addition, a cell in backward mode tended to stay near the surface longer than a cell in forward mode. This wall effect on the bacterial motion was independent of chemical modification of the glass surface. The macroscopic behavior is numerically simulated on the basis of experimental results and the significance of the phenomenon reported here is discussed.

Bacterial Physiological Phenomena↗
PubMed1995

Spermatozoa selected by a discontinuous Percoll density gradient exhibit better motion characteristics, more hyperactivation, and longer survival than direct swim-up.

OBJECTIVE: To determine if a discontinuous Percoll density gradient selects spermatozoa with different motion characteristics than direct swim-up. DESIGN: Controlled prospective study of the effect of two preparation techniques on spermatozoa from normal semen samples using computer-aided sperm analysis (CASA). SETTING: The Fertility laboratory, Queen Charlotte's Hospital, London, United Kingdom. PATIENTS: Eighteen male patients. INTERVENTIONS: Semen samples were divided into two equal parts. The first part was prepared by a direct swim-up whereas the other half was subjected to a three-layer discontinuous Percoll density gradient centrifugation. The separated samples were then examined at 30 minutes and 3, 6, and 24 hours by CASA. RESULTS: Although swim-up selected a higher proportion of motile spermatozoa, Percoll produced a greater yield of motile cells. Straight line velocity was similar for both methods throughout study. In contrast, spermatozoa isolated by Percoll exhibited a significantly higher curvilinear velocity and amplitude of lateral head displacement, which lasted for > or = 6 hours. These changes were accompanied by a significant reduction in linearity of progression. The most dramatic effect of Percoll was to produce significantly greater numbers of spermatozoa expressing hyperactivation. After both swim-up and Percoll there was a decline in progressive motility over the 24 hours, although this was only significant for swim-up. CONCLUSIONS: In normal semen, a discontinuous Percoll density gradient selects spermatozoa with better motion characteristics, more hyperactivation, and improved longevity compared with direct swim-up. In view of the relationship between sperm motion characteristics and fertilizing ability, we conclude that the three-layer discontinuous Percoll density gradient be adopted as the preferred method for the preparation of spermatozoa for assisted reproduction.

Adult↗
PubMed1997

Effects of swimming training on brown-adipose-tissue activity in obese ob/ob mice: GDP binding and UCP m-RNA expression.

Brown adipose tissue (BAT) of obese animals is generally in a relatively atrophied and thermogenically quiescent state. The aim of the current study was to investigate the effect of swimming training on BAT activity in lean and obese (ob/ob) mice. The trained mice underwent a 6-week endurance swimming training (1 h/day, 5 days/week) in water at 35-36 degrees C. The swimming training significantly increased BAT mass and its protein content in both the lean and obese mice, suggesting hypertrophy. After swimming training, the amounts of protein and guanosine 5'-diphosphate binding in the mitochondria recovered from BAT of both mice increased significantly as compared with the respective sedentary groups, whereas the uncoupling protein (UCP) content increased significantly only in lean mice. After swimming training, the level of UCP mRNA expression did not change substantially in lean mice but appeared to increase in obese mice. The results obtained here suggest that swimming training leads to an increase in the nonshivering thermogenesis of obese mice in addition to lean mice.

Adipose Tissue, Brown↗
PubMed1998

Swimming kinematics and respiratory behaviour of xenopus laevis larvae raised in altered gravity

We examined the respiratory behaviours and swimming kinematics of Xenopus laevis tadpoles hatched in microgravity (Space Shuttle), simulated microgravity (clinostat) and hypergravity (3 g centrifuge). All observations were made in the normal 1 g environment. Previous research has shown that X. laevis raised in microgravity exhibit abnormalities in their lungs and vestibular system upon return to 1 g. The tadpoles raised in true microgravity exhibited a significantly lower tailbeat frequency than onboard 1 g centrifuge controls on the day of landing (day0), but this behaviour normalized within 9 days. The two groups did not differ significantly in buccal pumping rates. Altered buoyancy in the space-flight microgravity tadpoles was indicated by an increased swimming angle on the day after landing (day1). Tadpoles raised in simulated microgravity differed to a greater extent in swimming behaviours from their 1 g controls. The tadpoles raised in hypergravity showed no substantive effects on the development of swimming or respiratory behaviours, except swimming angle. Together, these results show that microgravity has a transient effect on the development of locomotion in X. laevis tadpoles, most notably on swimming angle, indicative of stunted lung development. On the basis of the behaviours we studied, there is no indication of neuromuscular retardation in amphibians associated with embryogenesis in microgravity.

Journal Article↗
PubMed1998

Comparative kinematics and hydrodynamics of odontocete cetaceans: morphological and ecological correlates with swimming performance.

Propulsive morphology and swimming performance were compared for the odontocete cetaceans Delphinapterus leucas, Orcinus orca, Pseudorca crassidens and Tursiops truncatus. Morphological differences were apparent among the whales. The general body contour and low-aspect-ratio caudal flukes of D. leucas indicated that this species was a low-performance swimmer compared with the other species. Propulsive motions were video-taped as animals swam steadily in large pools. Video tapes were analyzed digitally using a computerized motion-analysis system. Animals swam at relative velocities ranging from 0.4 to 2.4 body lengths s-1. The stroke amplitude of the flukes decreased linearly with velocity for D. leucas, but amplitude remained constant for the other species. Tail-beat frequencies were directly related to relative swimming velocity, whereas the pitch angle of the flukes was inversely related to relative swimming velocity. Unsteady lifting-wing theory was used with regression equations based on kinematics to calculate thrust power output, drag coefficients and propulsive efficiency. Compared with other species, O. orca generated the largest thrust power (36.3 kW) and had the lowest drag coefficient (0.0026), whereas T. truncatus displayed the largest mass-specific thrust power (23.7 W kg-1) and P. crassidens had the highest efficiency (0.9). D. leucas did not swim as rapidly as the other species and had a comparatively higher minimum drag coefficient (0.01), lower mass-specific thrust power (5.2 W kg-1) and lower maximum efficiency (0.84). Minimum drag coefficients were associated with high swimming speeds, and maximum efficiencies corresponded with velocities in the range of typical cruising speeds. The results indicate that the kinematics of the propulsive flukes and hydrodynamics are associated with the swimming behaviors and morphological designs exhibited by the whales in this study, although additional factors will influence morphology.

Journal Article↗
PubMed1993

Health effects of attending a public swimming pool: follow up of a cohort of pupils in Paris.

OBJECTIVES: This study aimed to determine the health effects of attending a well-kept school swimming pool maintained according to French public health regulations. METHODS: This prospective month long study was carried out on a randomised sample of pupils aged 5 to 18 years who attended a private French school with two swimming pools. The children surveyed, helped by their parents, had to fill in questionnaires about their bathing habits and symptoms during the survey period. Inspections of the pool complex were made and these included physicochemical and bacteriological analyses of the pools' water. PARTICIPATION: The response rates achieved were 70% at primary and middle school levels but only 25% in the high school pupils. Because of this older teenagers were excluded from the final analysis (of 246 children). RESULTS: Compared with non-bathers, bathers experienced fatigue and eye irritation significantly more often (p < 0.001). The eyes were red (38% of bathers) and/or watery (16%) after swimming but this resolved spontaneously within 24 hours. Bathing behaviour (bath duration, head immersion, wearing swimming goggles) did not affect these incidence rates noticeably. There were no differences between bathers and non-bathers with regard to other symptoms, especially otolaryngological ones. This survey does not allow definite conclusions to be made about verrucas because 22% of non-bathers were exempted from swimming because of verrucas that they might have caught previously in a pool. CONCLUSIONS: Except for verrucas, the methodology was adequate and daily self reporting of symptoms was feasible. This college largely recruits pupils from higher social classes and is not therefore representative of schools in Paris.

Adolescent↗
PubMed1996

Hopping and swimming in the leopard frog, Rana pipiens: I. Step cycles and kinematics.

This study presents a model for the step cycle patterns used during both hopping and swimming by the leopard frog, Rana pipiens. The two behaviors are essentially similar in movement pattern and in the ways they are modified from quadrupedal gaits. In hopping, there is marked hind limb extension throughout stance. The swing begins with a suspension equivalent to the leap that occurs in a galloping or bounding quadruped. Following suspension, as the frog descends from the apex of its leap, the hind limbs remain posterior and in line with the spine while they flex. Near the end of flexion, there is a rapid downward rotation of the hindquarters to bring the hind feet underneath the body. This movement utilizes the planted forelimb as a pivot. A similar pattern of movement occurs in swimming; the stance (propulsion) phase involves extension at all hind limb joints. The swing (recovery) phase begins with the hind feet fully extended and includes a protracted gliding phase, equivalent to the suspension in the hop. The hind limb then recovers to its initial position during a flexion phase. Since there is no landing and the hind limbs remain lateral rather than ventral to the pelvis, less flexion occurs in the spine or the limb joints. In both behaviors, the extensor muscles of hip (M. semimembranosus), knee (M. cruralis), and ankle (M. plantaris longus) achieve their longest lengths, when they likely can produce near maximal force, at the beginning of extension. All three muscles shorten during extension, but, because they are multiple-joint muscles, the amount of shortening is relatively small (approximately 15%). Hopping and swimming in frogs are comparable asymmetrical gaits with the same relative contact intervals (25% of stride). The step cycles in both gaits are modified from quadrupedal locomotion in the same ways: by 1) loss of knee and ankle extension toward the ground prior to landing (or end of flexion in swimming), 2) loss of a yield phase on landing (or end of flexion in swimming), and 3) inclusion of extended suspensions in both gaits.

Animals↗
PubMed1996

The development of swimming behavior in the neurological mutant weaver mouse.

Weaver (wv/wv) mice have well-specified ontogenetic defects in both the cerebellum and striatum, but have not previously been evaluated systematically for patterns of motor development. In this study, the effects of the weaver mutation were evaluated through an examination of swimming behavior over the first 3 postnatal weeks. Detailed movement analyses of individual limb movements as well as interlimb coordination were used to evaluate the effects of the weaver mutation. Weaver mutant mice displayed a developmental lag in terms of swimming style relative to controls. They also displayed a generalized slowness in limb movements during the swim, which correlated with the developmental onset of use of a particular limb during the swim. However, basic motor patterns in weaver swimming continue to exhibit good overall coordination through the 3rd postnatal week, even though locomotor ataxia has become pronounced by this time. Our results indicate that specific and limited alterations in movement can be traced to very early in development (postnatal Day 3) in weaver mutant mice, a time at which the earliest biochemical and neuroanatomical deficits in these animals have been established. Our results also emphasize the need for systematic contextual analyses of movement to understand interlocking processes both in movement ontogeny and its disorders.

Animals↗
PubMedDate not supplied

Protective effects of long term dietary restriction on swimming exercise-induced oxidative stress in the liver, heart and kidney of rat.

In this study, we evaluated the hypothesis that long term dietary restriction would have beneficial effects on the oxidative stress and antioxidant enzyme systems in liver, heart and kidney in adult male rats undergoing different intensities of swimming exercise. Sixty male, Sprague-Dawley rats were assigned as either dietary restricted on every other week day (DR) or fed ad libitum (AL) groups, and each group was further subdivided into sedentary, endurance swimming exercise training (submaximal exercise) and exhaustive swimming exercise (maximal exercise) groups. Animals in the submaximal exercise group swam 5 days/week for 8 weeks, while maximal exercise was performed as an acute bout of exercise. In parallel with the increase in the intensity of the exercise, the degree of lipid peroxidation and protein oxidation were increased in both the DR and AL groups; however the rate of increase was lower in the DR group. Reduced glutathione (GSH), glutathione peroxidase (GSH-Px) and glutathione reductase (GR) enzyme activities were lower in the DR group than in the AL group. In parallel with the increase in exercise intensity, GSH and GR enzyme activities decreased, whereas an increase was observed in GSH-Px enzyme activity. In conclusion, the comparison between the DR and AL groups with the three swimming exercise conditions shows that the DR group is greatly protected against different swimming exercise-induced oxidative stress compared with the AL group.

Animals↗
PubMed2006

Swim test immobility in a genetic rat model of depression is modified by maternal environment: a cross-foster study.

The Flinders sensitive line (FSL) genetic animal model of depression exhibits marked immobility during forced swimming, an accepted index of depressive like behavior in rodent depression models. The present experiment tested the hypothesis that swim test behavior in the FSL rats is influenced in part by early experience, specifically maternal environment. Male FSL and control Flinders resistant line (FRL) pups were cross fostered onto dams of the same or complementary strain. Nest quality and dam behavior during pup retrieval were measured on PN5 and PN8, and swim test behavior assessed in the adult males on PN60. FSL rats reared by foster FRL dams were significantly less immobile than FSL rats raised by FSL dams, but still significantly more immobile that the two FRL groups, which did not differ from each other. FSL dams took significantly longer to retrieve their pups and dropped them more often than the FRL control dams. Moreover, strain differences in maternal retrieval behavior significantly predicted later swim test immobility in the FSL animals. These findings suggest that swim test immobility in the FSL rats is modified by maternal environment. In contrast, the FRL control rats were relatively insensitive to the influence of maternal environment. The FSL model offers promise for understanding the interactions of genetic vulnerabilities and environmental influences in the etiology of clinical depression.

Animals↗