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PubMed2003

[The study of contents of trihalomethanes in brine of a therapeutic swimming pool and in the swimming pool hall air].

The chlorination of iodide-bromide brines during exploitation of therapeutic pools at health resorts brings a hazard of generation of toxic trihalomethanes (THMs), especially bromide derivatives. The study was undertaken to establish the time changes of THM concentration in the pool brine and air in the pool hall. In the pool brine the concentration of THM increased from 40 mg/l at the beginning of the exploitation cycle up to 100 mg/l after 2 months of recirculating the pool water. In the pool hall air the concentration of THM varied from approximately 6 micrograms/m3 to 16.32 micrograms/m3. The values are the concentrations of total THMs per CHCl3, and fall within the range of limits currently admissible for drinking water (so in sport and recreational pools as well). However, they are from 2 to 5 times higher than the admissible level of THMs in indoor pools given in German standards DIN. An interesting finding was over 80% contribution of CHBr3 in the total THMs determined in the pool brine and its 55-59% contribution in the total THMs determined in the pool hall air.

Air↗
PubMed2006

The comparison of immobility time in experimental rat swimming models.

Rat swimming models have been used in studies about stress and depression. However, there is no consensus about interpreting immobility (helplessness or adaptation) in the literature. In the present study, immobility time, glucose and glycogen mobilization, corticosterone and the effect of desipramine and diazepam were investigated in two different models: swimming stress and the forced swimming test. Immobility time was lower in swimming stress than in the forced swimming test. Both swimming models increased corticosterone levels in comparison with control animal levels. Moreover, swimming stress induced higher corticosterone levels than the forced swimming test did [F(2,14)=59.52; p<0.001]. Liver glycogen content values differed from one another (swimming stress<forced swimming test<control), [F(2,17)=32.08; p<0.001]. The glycogen content values in the gastrocnemius [F(2,16)=11.35; p=0.026] and soleus [F(2,16)=8.68; p=0.006] muscles were lower during swimming stress in comparison with the forced swimming test and control. The immobility time was recorded and measured in another group treated with desipramine and diazepam in two protocols: a single session of forced swimming test or swimming stress and two sessions (pre- and retest) of forced swimming model or swimming stress. Desipramine decreased the immobility time in the forced swimming test in both the single [F(2,25)=20.63; p<0.0001] and retest [F(2,37)=7.28; p=0.002] swimming session, without changes in the swimming stress model. Diazepam increased the immobility time in the swimming stress but not in the forced swimming test during the single [F(2,26)=11.24; p=0.0003] and retest sessions [F(2,38)=4.17; p=0.02]. It was concluded that swimming stress and the forced swimming test induced different behavior, hormonal and metabolic responses and represented different situations to the animal.

Animals↗
PubMed1985

Habituation of swimming activity in the medicinal leech.

Tactile stimulation (light stroking) of a body wall flap attached to the ventral nerve cord of the medicinal leech evokes episodes of swimming activity. This swimming response undergoes habituation, involving changes in swim initiation and swim maintenance. Repeated stimulation of the body wall flap evoked swimming activity between three and 39 times before this response failed. During repetitive stimulation, the length of swim episodes decreased by about 50%. The number of swim episodes which could be elicited was not correlated with swim episode length. Following habituation, swim initiation showed significant spontaneous recovery, but swim episode length returned only to 60% of control values. In preparations where spontaneous recovery was followed by rehabituation, the number of swim episodes elicited declined with each habituation-recovery sequence. Additional stimulation immediately following habituation trials had a dual effect: recovery of the swimming response was delayed, but the lengths of swim episodes following spontaneous recovery were increased. Pinching the body wall flap immediately restored the swimming response in an habituated preparation. Swim initiation habituated more rapidly during stimulation of anterior body wall flaps than during stimulation of mid-body or posterior flaps. However, swim length was independent of this regional variation in swim responsiveness. The number of swim episodes elicited by stimulation of body wall flaps attached to posterior or anterior segments depended upon whether this segment was stimulated before or after other flaps. In contrast, in mid-body segments there was no evidence for such stimulus generalization. The lengths of swim episodes elicited during sequential stimulation of several body wall flaps were independent of the stimulation sequence. We propose that separate processes control swim initiation and swim maintenance. These processes must be repeated in most, if not all, of the segmental ganglia of the leech ventral nerve cord.

Action Potentials↗
PubMed1995

Neuronal factors influencing the decision to swim in the medicinal leech.

The initiation of leech (Hirudo medicinalis) swimming in isolated segmental nerve cord preparations requires only excitation of segmental swim gating and swim oscillatory interneurons. However, several observations indicate that when the entire isolated central nervous system (head ganglion through tail ganglion) is used, neuronal inputs from the head ganglion other than excitatory inputs to the segmental swim-generating network influence whether swimming results in response to a given stimulus. In this study, experiments were performed to demonstrate that the initiation of swimming is controlled by two parallel pathways emanating from the head ganglion that have opposite effects on the segmental swim-generating network. One pathway, the swim-activating system, excites the segmental swim-generating network, while the other pathway, the swim-inactivating system, suppresses it. The balance between the effects that the swim-activating and inactivating systems have on the segmental swim-generating network determines whether swimming occurs. Moreover, we identified a pair of interneurons, cells SIN1, in the leech head ganglion whose spiking activity must be suppressed in order for swimming to be initiated since their activity is incompatible with swimming. Depolarization of cell SIN1 during swimming indirectly inhibits segmental swim-gating interneurons and terminates ongoing swimming activity. Thus, cells SIN1 are most likely part of the swim-inactivating system in the leech head ganglion.

Animals↗
PubMed2005

Detection and risk assessment of adenoviruses in swimming pool water.

AIMS: The role of swimming pool water as a source of human adenovirus (HAd) infection has previously been demonstrated. In this study, the risk of infection of HAds detected in a survey of swimming pool water from two indoor and one outdoor swimming pools over a period of 1 year was assessed. METHODS AND RESULTS: The HAds were concentrated from 1 l grab samples of swimming pool water using a silicon dioxide-based method. The extracted HAd DNA was amplified by means of a nested PCR method. Adenoviruses were detected in four of 26 samples (15.4%) from the indoor swimming pool A, eight of 38 samples (21.1%) from the indoor swimming pool B and three of 28 samples (10.7%) from the outdoor swimming pool C. Application of these results in an exponential risk assessment model indicated a daily risk of infection of 2.61 x 10(-3) for swimming pool A, 3.69 x 10(-3) for swimming pool B and 1.92 x 10(-3) for swimming pool C assuming a daily consumption of 30 ml of swimming pool water. CONCLUSIONS: No acceptable (tolerable) risk of infection has yet been recommended for swimming pool water. However, the quality of swimming pool water is generally expected to be similar to that of drinking water. One infection per 10 000 consumers per year has been recommended for drinking water. The risk of HAd infections calculated for the swimming pool water under investigation exceeded this acceptable risk. SIGNIFICANCE AND IMPACT OF THE STUDY: The finding that swimming pool water which conforms to generally accepted specifications for treatment, disinfection and indicator organisms constituted a risk of HAd infection, has implications for the swimming pool industry. The formulation of acceptable (tolerable) risks of infection for swimming pool water may be essential. Specifications will, therefore, have to be formulated to ensure that swimming pool water conforms to the acceptable risk of infection.

Adenoviridae↗
PubMed1999

A kinematic comparison of forward and backward swimming in the eel anguilla anguilla

In addition to forward undulatory swimming, eels (and some other elongated swimmers) can swim backwards in a similar way. We compared the kinematics (wave speed, cycle frequency, amplitude, local bending and estimated muscle strain) of forward and backward swimming in the European eel Anguilla anguilla. Both swimming modes are characterised by a wave of undulation that travels over the body in the direction opposite to that of swimming. We observe two major kinematic differences. First, the slope of wave frequency against swimming speed is significantly higher for backward than for forward swimming. Second, the amplitude profile along the body of the propulsive wave differs greatly. During forward swimming, the yaw at the head is minimal and the amplitude of the propulsive wave increases to approximately 15 % (left-to-right) of total body length towards the tail tip. During backward swimming, the amplitude profile is rather uniform along the body (with values similar to the tail-tip amplitude during forward swimming), resulting in considerable lateral head oscillation. Strikingly, the head remains approximately parallel to the swimming direction, which presumably enhances visual and acoustico-lateral perception. Furthermore, muscle strain is much higher in the rostral part of the body during backward swimming than during forward swimming. Values for stride length and propeller efficiency suggest that backward undulatory swimming is mechanically less efficient than forward swimming. We suggest that the typical anguilliform body shape is an important feature that allows these animals to swim backwards using an undulatory mechanism that resembles the forward undulatory swimming mechanism. Most other fishes, if able to swim backwards at all, do so using fin oscillations or undulations.

Journal Article↗
PubMed1986

Initiation of swimming activity by trigger neurons in the leech subesophageal ganglion. I. Output connections of Tr1 and Tr2.

The aim of this study was to identify neurons in the subesophageal ganglion of the medicinal leech which initiate swimming activity and to determine their output connections. We found two bilaterally symmetrical pairs of interneurons, Tr1 and Tr2, located in the first division of the subesophageal ganglion which initiate swimming activity in the isolated nervous system when depolarized with brief (1-3 s) current pulses. Tr1 and Tr2 are considered trigger neurons because elicited swimming episodes outlast the stimulus duration, and because the length of elicited swim episodes is nearly independent of the intensity with which Tr1 and Tr2 are stimulated. Tr1 and Tr2 have similar morphologies. The neurites of both cells cross contralaterally in the subesophageal ganglion, project posteriorly, and exit the subesophageal ganglion in the contralateral connective. The axons of Tr1 and Tr2 extend as far posterior as segmental ganglion 18 of the ventral nerve cord. Tr1 provides direct excitatory drive to three groups of segmental neurons which are capable of initiating swimming: swim-initiating interneurons (cells 204 and 205), serotonin-containing interneurons (cells 61 and 21), and the serotonergic Retzius cells. In addition, all Retzius cells in the subesophageal ganglion are excited directly by Tr1. These three groups of neurons are excited even if Tr1 stimulation is subthreshold for swim initiation. In contrast to Tr1, Tr2 stimulation evokes transient inhibition in swim-initiating and serotonin-containing interneurons, and has little immediate effect on Retzius cells. In addition, Tr2 indirectly inhibits several oscillator neurons, including cells 208, 33, and 60. When Tr1 is stimulated during a swimming episode the swim period decreases for several cycles, while stimulation of Tr2 during swimming episodes reliably resets the ongoing swimming rhythm. Our findings indicate that Tr1 and Tr2 are trigger neurons which initiate swimming activity by different pathways. These neurons also have functional interactions with the swim oscillator network since either Tr1 or Tr2 stimulation during swimming can modulate the ongoing swimming rhythm.

Animals↗