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A meta-analysis of swimming and water precautions.

OBJECTIVE: To reconcile conflicting reports concerning the incidence of otorrhea in children with tympanostomy tubes who swim without ear protection. STUDY SELECTION: Articles were identified by MEDLINE search, Current Contents, and references from review articles, textbook chapters, and retrieved reports. Controlled trials of water precautions following tympanostomy tube placement were selected by independent observers and scored on 10 measures of study validity. Five English-language articles met all inclusion criteria. DATA EXTRACTION: Data were abstracted for an endpoint of otorrhea following swimming without ear protection with a minimum follow-up of 6 weeks. DATA SYNTHESIS: Pooled analysis of 619 children revealed a rate difference of -5.04 (95% confidence interval [CI], -11.62 to 1.54). No significant difference in the incidence of otorrhea was noted between patients who swam without ear protection and nonswimmers. CONCLUSION: There is no increase in incidence of otorrhea in children who swim without ear protection compared with children who do not swim following tympanostomy tube placement.

Cerebrospinal Fluid Otorrhea↗

Effects of behavioral and morphological plasticity on risk of predation in a Neotropical tadpole.

Predator-induced phenotypic plasticity is widespread among aquatic animals, however the relative contributions of behavioral and morphological shifts to reducing risk of predation remain uncertain. We tested the phenotypic plasticity of a Neotropical tadpole ( Rana palmipes) in response to chemical cues from predatory Belostoma water bugs, and how phenotype affects risk of predation. Behavior, morphology, and pigmentation all were plastic, resulting in a predator-induced phenotype with lower activity, deeper tail fin and muscle, and darker pigmentation. Tadpoles in the predator cue treatment also grew more rapidly, possibly as a result of the nutrient subsidy from feeding the caged predator. For comparison to phenotypes induced in the experiment, we quantified the phenotype of tadpoles from a natural pool. Wild-caught tadpoles did not match either experimentally induced phenotype; their morphology was more similar to that produced in the control treatment, but their low swimming activity was similar to that induced by predator cues. Exposure of tadpoles from both experimental treatments and the natural pool to a free-ranging predator confirmed that predator-induced phenotypic plasticity reduces risk of predation. Risk of predation was comparable among wild-caught and predator-induced tadpoles, indicating that behavioral shifts can substantially alleviate risk in tadpoles that lack the typical suite of predator-induced morphological traits. The morphology observed in wild-caught tadpoles is associated with rapid growth and high competition in other tadpole species, suggesting that tadpoles may profitably combine a morphology suited to competition for food with behaviors that minimize risk of predation.

Analysis of Variance↗

An improved Morris Water Maze tracking algorithm for psychophysical studies.

An algorithm to track a rat swimming in a Morris Water Maze has been developed. The system is automatically configured to any pool and relative suitable light conditions. It tracks the rat's position and head pose 10 times per second. The output data is displayed in a bitmap and also in a text file. The system was tested with an X - Y plotter using a simulated rat swimming in the maze. Known signals were provided to a model rat and compared to the position and pose information provided by the tracking algorithm. The algorithm was able to track rat velocities up to 2.32 m/s, localize rat position to 4 mm within the maze, and provide head pose information. Early prototypes of the algorithm were also used to track actual rats in a water maze.

Algorithms↗

Effects of bovine spermatozoa preparation on embryonic development in vitro.

The aim of our research was to examine the ability of density gradient preparation BoviPure and swim up method on bull sperm separation and in vitro embryo production (IVP) systems. Frozen/thawed semen from six Simmental bulls was pooled and treated using both methods. The sperm motility, concentration, membrane activity, membrane integrity and acrosomal status were evaluated and compared before and after sperm processing using BoviPure and swim up methods. We also evaluated and compared cleavage rates, embryo yield and quality between the methods. There were significant differences (P < 0.05) between the sperm characteristics before and after BoviPure, but not after swim up method. However, there were significant differences for sperm results among those two mentioned methods. A total of 641 oocytes were matured and fertilized in vitro and cultured in SOFaaBSA. The percentage of cleavage (Day 2) and the percentage of hatched embryos (Day 9) were similar for both methods. However, embryo production rate (Day 7) was significantly higher using BoviPure method (P < 0.05). Also, total cell number and embryo differential staining (inner cell mass and trophectoderm cells) of Day 7 morulas and blastocysts showed that BoviPure treated sperm displayed higher quality embryos compared to swim up method (P < 0.05). Our results indicate that BoviPure method has an enhanced capacity in sperm selection for in vitro embryo production when compared with swim up method. So, we concluded that BoviPure could be considered as a better alternative to swim up method for separating bull spermatozoa from frozen/thawed semen for IVP of bovine embryos.

Animals↗

Oxygen consumption during exercise in a heated pool.

The heated hydrotherapy pool is a common exercise site for patients with painful musculoskeletal conditions. Oxygen consumption of swimming is 87 to 89% of maximum in postmyocardial infarction patients according to one recent investigation. We studied 13 able-bodied subjects to test the hypothesis that enough energy could be expended during various forms of hydrotherapy to produce both an aerobic training effect and a risk to patients with coronary artery disease. Oxygen consumption (VO2) was measured in six settings: resting supine; resting seated shoulder deep in the pool (36C); walking at comfortable speed in chest-deep water; running at the fastest speed possible in chest-deep water; using hand paddles; and running in place at shoulder depth. The mean VO2 expressed in ml/kg/min (and metabolic equivalents) were 4.91 (1.00), 4.93 (1.02), 9.34 (2.01), 27.79 (6.23), 18.25 (4.30) and 29.11 (7.09) respectively, suggesting that the more vigorous exercises stress aerobic capacity heavily but not excessively.

Adult↗

Characteristics of elite open-water swimmers.

Open-water swimming (5, 10, and 25 km) has many unique challenges that separate it from other endurance sports, like marathon running and cycling. The characteristics of a successful open-water swimmer are unclear. The purpose of this study was to determine the physical and metabolic characteristics of a group of elite-level open-water swimmers. The open-water swimmers were participating in a 1-week training camp. Anthropometric, metabolic, and blood chemistry assessments were performed on the athletes. The swimmers had a VO(2)peak of 5.51 +/- 0.96 and 5.06 +/- 0.57 ml.kg(-1).min(-1) for males and females, respectively. Their lactate threshold (LT) occurred at a pace equal to 88.75% of peak pace for males and 93.75% for females. These elite open-water swimmers were smaller and lighter than competitive pool swimmers. They possess aerobic metabolic alterations that resulted in enhanced performance in distance swimming. Trainers and coaches should develop dry-land programs that will improve the athlete's muscular endurance. Furthermore, programs should be designed to increase the LT velocity as a percentage of peak swimming velocity.

Adolescent↗

A dye mixture (Neurobiotin and Alexa 488) reveals extensive dye-coupling among neurons in leeches; physiology confirms the connections.

Although the neuronal circuits that generate leech movements have been studied for over 30 years, the list of interneurons (INs) in these circuits remains incomplete. Previous studies showed that some motor neurons (MNs) are electrically coupled to swim-related INs, e.g., rectifying junctions connect IN 28 to MN DI-1 (dorsal inhibitor), so we searched for additional neurons in these behavioral circuits by co-injecting Neurobiotin and Alexa Fluor 488 into segmental MNs DI-1, VI-2, DE-3 and VE-4. The high molecular weight Alexa dye is confined to the injected cell, whereas the smaller Neurobiotin molecules diffuse through gap junctions to reveal electrical coupling. We found that MNs were each dye-coupled to approximately 25 neurons, about half of which are likely to be INs. We also found that (1) dye-coupling was reliably correlated with physiologically confirmed electrical connections, (2) dye-coupling is unidirectional between MNs that are linked by rectifying connections, and (3) there are novel electrical connections between excitatory and inhibitory MNs, e.g. between excitatory MN VE-4 and inhibitory MN DI-1. The INs found in this study provide a pool of novel candidate neurons for future studies of behavioral circuits, including those underlying swimming, crawling, shortening, and bending movements.

Animals↗

Contribution of egocentric spatial memory to place navigation of rats in the Morris water maze.

Place navigation in the Morris water maze can be directed by memory of the target coordinates relative to remote landmarks (allocentric) or by the memory of the start-goal route (egocentric). When the start and goal positions remain constant and visual cues are eliminated by darkness, memory of the route may become decisive. This assumption was tested in 10 male hooded rats using an infrared television tracking system allowing navigation training in the dark. In Expt. 1, these animals were trained to swim in the dark from the start at the S rim of the pool to the goal position in the center of the NW quadrant of the pool. Mean escape latencies decreased from 47 s initially to 16 s during the 24 daily sessions. Another group of 10 male hooded rats learned the same task in the light. Mean escape latencies decreased from 20 s initially to 5 s during 4 daily sessions. In Expt. 2, possible allocentric location of the target was tested in the same rats by rotating both the start and goal positions by 90 degrees counterclockwise (i.e., to E-SW and later to N-SE). Mean escape latency during 5 days after the first rotation increased to 24 s, but returned back to the asymptotic level of 18 s after the second rotation. The same change of the start and goal position (from S-NW to E-SW) in the light only increased escape latency in the first session. In Expt. 3, both the goal position and route direction were changed to N-SW. Surprisingly, the animals rapidly acquired a new heading angle at the start and mean escape latencies were not significantly changed. It is concluded that overtrained place navigation in darkness can be easily changed to a new direction.

Animals↗

Training techniques to improve endurance exercise performances.

In previously untrained individuals, endurance training improves peak oxygen uptake (VO2peak), increases capillary density of working muscle, raises blood volume and decreases heart rate during exercise at the same absolute intensity. In contrast, sprint training has a greater effect on muscle glyco(geno)lytic capacity than on muscle mitochondrial content. Sprint training invariably raises the activity of one or more of the muscle glyco(geno)lytic or related enzymes and enhances sarcolemmal lactate transport capacity. Some groups have also reported that sprint training transforms muscle fibre types, but these data are conflicting and not supported by any consistent alteration in sarcoplasmic reticulum Ca2+ ATPase activity or muscle physicochemical H+ buffering capacity. While the adaptations to training have been studied extensively in previously sedentary individuals, far less is known about the responses to high-intensity interval training (HIT) in already highly trained athletes. Only one group has systematically studied the reported benefits of HIT before competition. They found that >or=6 HIT sessions, was sufficient to maximally increase peak work rate (W(peak)) values and simulated 40 km time-trial (TT(40)) speeds of competitive cyclists by 4 to 5% and 3.0 to 3.5%, respectively. Maximum 3.0 to 3.5% improvements in TT(40) cycle rides at 75 to 80% of W(peak) after HIT consisting of 4- to 5-minute rides at 80 to 85% of W(peak) supported the idea that athletes should train for competition at exercise intensities specific to their event. The optimum reduction or 'taper' in intense training to recover from exhaustive exercise before a competition is poorly understood. Most studies have shown that 20 to 80% single-step reductions in training volume over 1 to 4 weeks have little effect on exercise performance, and that it is more important to maintain training intensity than training volume. Progressive 30 to 75% reductions in pool training volume over 2 to 4 weeks have been shown to improve swimming performances by 2 to 3%. Equally rapid exponential tapers improved 5 km running times by up to 6%. We found that a 50% single-step reduction in HIT at 70% of W(peak) produced peak approximately 6% improvements in simulated 100 km time-trial performances after 2 weeks. It is possible that the optimum taper depends on the intensity of the athletes' preceding training and their need to recover from exhaustive exercise to compete. How the optimum duration of a taper is influenced by preceding training intensity and percentage reduction in training volume warrants investigation.

Adaptation, Physiological↗

Nonfatal and fatal drownings in recreational water settings--United States, 2001-2002.

Drowning is the seventh leading cause of unintentional injury deaths for all ages and the second leading cause of all injury deaths in children aged 1-14 years. Many of these injuries occur in recreational water settings, including pools, spas/hot tubs, and natural water settings (e.g., lakes, rivers, or oceans). To examine the incidence and characteristics of nonfatal and fatal unintentional drownings in recreational water settings, CDC analyzed 2001-2002 data from the National Electronic Injury Surveillance System All Injury Program (NEISS-AIP) and National Vital Statistics System (NVSS) death certificate data from 2001. This report summarizes that analysis, which indicated that, during 2001-2002, an estimated 4,174 persons on average per year were treated in U.S. hospital emergency departments (EDs) for nonfatal unintentional drowning injuries in recreational water settings. Approximately 53% of persons required hospitalization or transfer for more specialized care. During 2001, a total of 3,372 persons suffered fatal unintentional drownings in recreational settings. Nonfatal and fatal injury rates were highest for children aged < or =4 years and for males of all ages. To reduce the number of drownings, environmental protections (e.g., isolation pool-fences and lifeguards) should be adopted; alcohol use should be avoided while swimming, boating, or water skiing or while supervising children; and all participants, caregivers, and supervisors should be knowledgeable regarding water-safety skills and be trained in cardiopulmonary resuscitation (CPR).

Adolescent↗

Post-swim orthostatic intolerance in a marathon swimmer.

Two swims (1993 and 1994) are described which led to post-swim orthostatic intolerance and one episode of syncope in a 50/51-yr-old well-trained and experienced marathon swimmer. The swims of 33 km and 38 km took 12 h 30 s and 17 h 35 min, respectively. Water temperature in each swim was above 23 degrees C and rectal core-temperature stayed above 37.0 degrees C. Air temperatures differed, ranging from 23 degrees to 37 degrees C and 15 degrees to 21 degrees C, respectively. Regular fluid consumption totalled approximately 5.0 and 6.0 1, respectively. Fifteen minutes after completing the 1993 swim, the swimmer experienced orthostatic intolerance and fainted at the lakeside; hospital tests revealed an elevated creatine phosphokinase (CK) of 521 U.l-1. The 1994 swim was abandoned due to severe muscle cramps and CK was found to be markedly elevated at 909 U.l-1. Orthostatic intolerance was recorded in both cases; however, no cardiac abnormalities were found. After overnight rest and intravenous saline infusions of 3.0 and 1.5 l, respectively, the orthostatic intolerance was relieved. Based on previous descriptions of exercise-associated collapse in marathon runners, the swimmer's orthostatic intolerance and syncope are attributed to blood pooling in his legs due to inactivation of the venous muscle pump on completion of the swim.

Body Temperature↗

Identification of Naegleria fowleri in domestic water sources by nested PCR.

The free-living amoeboflagellate Naegleria fowleri is the causative agent of primary amoebic meningoencephalitis (PAM), a rapidly fatal disease of the central nervous system. In the United States, the disease is generally acquired while swimming and diving in freshwater lakes and ponds. In addition to swimming, exposure to N. fowleri and the associated disease can occur by total submersion in bathwater or small backyard wading pools. In the present study, swipe samples and residual pipe water from homes in Arizona were examined for N. fowleri by nested PCR due to the death of two previously healthy children from PAM. Since neither child had a history of swimming in a freshwater lake or pond prior to the onset of disease symptoms, the domestic water supply was the suspected source of infection. Of 19 samples collected from bathroom and kitchen pipes and sink traps, 17 samples were positive for N. fowleri by PCR. A sample from a Micro-Wynd II filter was obtained by passing water from bathtubs through the filter. Organisms attached to the filter also tested positive by PCR. The two samples that tested negative for N. fowleri were one that was obtained from a kitchen sink trap and a swipe sample from the garbage disposal of one home.

Amebiasis↗

Effect of exercise training on plasma cholesterol and cholesterol kinetics in adult female rats.

Adult female rats fed laboratory chow of low cholesterol content were trained by swimming for 77 days. Plasma cholesterol concentration decreased 38% compared to sedentary controls. Whole body cholesterol metabolism was studied by injection of [14C]cholesterol tracer and determination of the plasma cholesterol-specific activity during the last 49 days of the experiment. The rate constant for elimination of cholesterol from the body was 31% higher in swimming than in sedentary animals, and the size of the rapidly-exchanging cholesterol pool was 28% smaller. These results suggest that enhanced cholesterol excretion or catabolism accompanies exercise training in the rat.

Animals↗

Rats exposed prenatally to alcohol exhibit impairment in spatial navigation test.

Prenatal exposure to ethanol causes learning disabilities and low I.Q. scores. The objective of the present studies was to investigate whether exposure of rats to ethanol in utero, would induce a deficit in spatial memory in adult life. Pregnant rats were fed with an ethanol diet from day 1 of pregnancy till parturition. Control rats were either pair-fed with an isocaloric sucrose diet or were fed with lab-chow ad libitum. On the first day of birth, offspring exposed to ethanol in utero were placed with a control mother fed with lab-chow, while offspring of the lab-chow fed dams were placed with ethanol-treated dams. At 40, 60 and 90 days postnatally, behavioral testing was performed using the Morris swim maze, a test of spatial memory. Results indicated that the offspring exposed to ethanol in utero presented deficits in spatial memory processes. Ethanol did not completely block the learning of the swim maze task but the alcohol-exposed offspring exhibited longer latencies to perform the task, swam longer distances prior to locating and climbing onto the platform, and when the platform was removed, searched for it in all 4 quadrants of the pool. Restricted caloric intake during gestation and maternal behavior in early postnatal life also induced deficits in the performance on the swim maze task. However, these deficits were mild and short-lasting being absent at 60 and 90 days of age. In contrast, the deficits induced by ethanol were more severe and longer-lasting, being present in adult life.

Animals↗

Thalamic and hippocampal mechanisms in spatial navigation: a dissociation between brain mechanisms for learning how versus learning where to navigate.

Various studies of hippocampus and medial thalamus (MT) suggest that these brain areas play a crucial, marginal, or no essential role in spatial navigation. These divergent views were examined in experiments using electrolytic Lesions of fimbria-fornix (FF) or radiofrequency or neurotoxic Lesions of MT of rats subsequently trained to find a stable visible (experiment 1) or hidden platform (experiments 2 and 3) in a water maze (WM) pool. Rats with electrolytic Lesions of FF or radiofrequency Lesions of MT were impaired in swimming to a stable visible platform, particularly the MT Lesion Group, suggesting impairment of WM strategies acquisition. Additional Lesioned rats were then tested in a hidden platform version of the WM task. Some rats were given Morris's nonspatial pretraining prior to Lesioning to provide them with training in the required WM behavioral strategies. Nonspatially Pretrained rats with FF Lesions eventually were able to navigate to the hidden platform, but the accuracy of place responding was impaired. This impairment occurred without problems in the motoric control of swimming or the use of WM behavioral strategies, suggesting that these rats had a spatial mapping impairment. Radiofrequency MT Lesions blocked acquisition of WM behavioral strategies by Naive rats throughout 3 days of training, severely impairing performance on all aspects of the hidden platform task. Nonspatially Pretrained rats given the same MT Lesions readily learned the hidden platform location and were indistinguishable from controls throughout spatial training. Rats given neurotoxic Lesions of MT for removal of cells were only mildly impaired and improved considerably during training, suggesting an important role for fibers of passage in WM strategies learning. The results provide a clear dissociation between a role for MT in learning WM behavioral strategies and the hippocampal formation in spatial mapping and memory. This is the first identification of a brain area, MT, that is essential for learning behavioral strategies that by themselves do not constitute the solution to the task but are necessary for the successful use of an innate learning ability: place response learning using spatial mapping.

Analysis of Variance↗

Does human semen contain a functional haemostatic system? A possible role for Tissue Factor Pathway Inhibitor in fertility through semen liquefaction.

There is already evidence that a few components of the haemostatic system exist in semen. If these comprise a functional system, they may have a role in seminal clotting and liquefaction processes and ultimately may influence fertility. What might be expected in semen as collected from fertility clinics i.e., after having both coagulated and subsequently liquefied is uncertain. It does however still contain significant amounts of Tissue Factor (TF) although its effect on semen quality remains poorly understood. The present study analyses semen for Tissue Factor Pathway Inhibitor (TFPI). Measurements were made in seminal plasma, swim-up sperm and prostasomes and its relationship with conventional fertility parameters assessed. TFPI antigen levels in seminal plasma were measured in a total of 176 subjects using an Enzyme-linked immunosorbent assay (ELISA). These include sub-fertile (n=37), normally fertile (n=40), fertile sperm donor (n=34), vasectomized subjects (n=65) and in a further group defined by normality in several parameters derived from the World Health Organization (WHO) fertility criteria and termed "pooled normal semen parameters" (PNSP). For characterization studies, both TFPI activity and antigen were measured on whole semen, swim-up sperm and prostasome-rich fraction (n=5). TFPI levels were significantly higher in normal men as compared to sub-fertile (P<0.01) or vasectomized subjects (P<0.001). TFPI levels were even higher in the donor quality semen and the PNSP group. TFPI levels also correlated with semen liquefaction time, normal semen viscosity, sperm progression, percentage of motile sperm and sperm counts (density). In conclusion, the present finding substantiates the concept of an active clotting system in human semen. TFPI could regulate the activity of abundant TF, as it does elsewhere. Given a functional set of coagulation factors in semen, the TF/TFPI balance might impinge on its liquefaction and hence on global fertility.

Adult↗