Anesthetic MS-222 eliminates nerve and muscle activity in frogs used for physiology teaching laboratories

Frogs are routinely used in physiology teaching laboratories to demonstrate important physiological processes. There have been recent directives that promote the use of the anesthetic MS-222 (tricaine methanesulfonate), rather than lowering body temperature with a cold water bath to prepare reptiles and amphibians for physiological experiments or euthanasia. Indeed, the most recent edition of the American Veterinary Medical Association (AVMA) Guidelines for the Euthanasia of Animals proclaims that chilling in water is not an appropriate method and advocates for the usage of MS-222 or other anesthetics. However, prominent researchers have responded to this position by highlighting evidence that cooling ectothermic vertebrates is, in fact, an effective and appropriate method. Furthermore, MS-222 is a known voltage-gated Na+ channel blocker, and this anesthetic’s impact on the physiology of excitable tissues suggests that its use might be incompatible with experiments on nerve and muscle tissues. In the present study, I examined the effects of MS-222 at a concentration of 1.5 g/l on nerve, skeletal muscle, and cardiac muscle physiology of frogs. I found that immersion of frogs in this anesthetic blocked basic nerve and muscle physiology, making the frogs unsuitable for laboratory experiments. Applying MS-222 directly to the sciatic nerve dramatically blocked normal excitation-contraction coupling in skeletal muscle preparations, and direct application to the heart caused the organs to stop contracting. Based on these results, I conclude that MS-222 at the concentration studied may be incompatible with physiological preparations that rely on electrically excitable tissues for their normal function. Physiology educators who must use MS-222 with frogs should empirically determine an appropriate dosage and recovery time before using the anesthetic in the teaching laboratory.

Postexercise Impact of Ice-Cold Water Bath on the Oxidant-Antioxidant Balance in Healthy Men

The aim of the study was to determine the effect of a 5 min head-out ice-cold water bath on the oxidant-antioxidant balance in response to exercise. The crossover study included the subjects (n=24; aged28.7±7.3years) who performed two identical stationary cycling bouts for 30 min and recovered for 10 min at room temperature (RT=20°C; session 1) or in a pool with ice-cold water (ICW=3°C, 5 min immersion; session 2). The concentration of thiobarbituric acid reactive substances (TBARS) in blood plasma (TBARSpl) and erythrocytes (TBARSer) and the erythrocytic activity of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) were measured three times during each of the two study sessions: before the exercise (baseline) and 20 and 40 min after the appropriate recovery session. Lower concentration of TBARSpl 40 min after postexercise recovery in ICW was revealed as compared with that after recovery at RT (P<0.05). Moreover, a statistically significant postexercise increase in the TBARSpl and TBARSer concentrations was found (P<0.01andP<0.05, resp.). A short-term ice-cold water bath decreases postexercise lipid peroxidation.

A Study on Moulding Technology of Starch-Based Totally-Biodegradable Plastic Products

Based on monofactorial comparison experiment, the following two excellent technological formations was derived for the production of starch-based totally-biodegradable tray via extruding, pelleting, slicing, and sucking molding: The first formulation: 40% of starch, 12.5% of DOP, 5% of EVA, 15% of polyvinyl alcohol, 20% of talc power and calcium carbonate, and 7.5% of other materials. The material temperature in high-speed kneader was about 90°C, rotation velocity was 600 r/min, kneading duration was 5~10 minutes, diameter of screw stem of extruder was 90 mm, ratio of length versus diameter of screw stem (L/D) was 44, rotation velocity of the screws stem was 40~50 r/min. Temperature in four segments of extruder were 145°C, 155 °C, 150°C, and 160°C respectively, and temperature in extruder head was 170 °C; the material rod extruded was set while passing a cold water bath, and then was cut to pellets whose size was 3 mm×3 mm; the latter was transformed into slices and subject to sucking molding after predrying; temperature of sucking molding was 180~190°C, and sucking molding duration was 15~20 seconds. The second formulation: 60% of starch, 15% of DOP, 5% of PHB, 15% of polyvinyl alcohol, and 5% of other materials. All technological parameters were the same with that for the first formulation. According to the test result of Chinese institute of plastic processing, the biodegradation ratio of the tray made through the above treatment 1 and 2 in 30 days amounted to 54.2% and 70.6% respectively, which showed that a satisfied biodegradation effect was realized.

Interleukin-6 Responses to Water Immersion Therapy After Acute Exercise Heat Stress: A Pilot Investigation

Context Cold-water immersion is the criterion standard for treatment of exertional heat illness. Cryotherapy and water immersion also have been explored as ergogenic or recovery aids. The kinetics of inflammatory markers, such as interleukin-6 (IL-6), during cold-water immersion have not been characterized. Objective To characterize serum IL-6 responses to water immersion at 2 temperatures and, therefore, to initiate further research into the multidimensional benefits of immersion and the evidence-based selection of specific, optimal immersion conditions by athletic trainers. Design Controlled laboratory study. Setting Human performance laboratory Patients or Other Participants Eight college-aged men (age = 22 ± 3 years, height = 1.76 ± 0.08 m, mass = 77.14 ± 9.77 kg, body fat = 10% ± 3%, and maximal oxygen consumption = 50.48 ± 4.75 mL·kg−1·min−1). Main Outcome Measures Participants were assigned randomly to receive either cold (11.70°C ± 2.02°C, n = 4) or warm (23.50°C ± 1.00°C, n = 4) water-bath conditions after exercise in the heat (temperature = 37°C, relative humidity = 52%) for 90 minutes or until volitional cessation. Results Whole-body cooling rates were greater in the cold water-bath condition for the first 6 minutes of water immersion, but during the 90-minute, postexercise recovery, participants in the warm and cold water-bath conditions experienced similar overall whole-body cooling. Heart rate responses were similar for both groups. Participants in the cold water-bath condition experienced an overall slight increase (30.54% ± 77.37%) in IL-6 concentration, and participants in the warm water-bath condition experienced an overall decrease (−69.76% ± 15.23%). Conclusions We have provided seed evidence that cold-water immersion is related to subtle IL-6 increases from postexercise values and that warmer water-bath temperatures might dampen this increase. Further research will elucidate any anti-inflammatory benefit associated with water-immersion treatment and possible multidimensional uses of cooling therapies.

Cold-Water Immersion and the Treatment of Hyperthermia: Using 38.6°C as a Safe Rectal Temperature Cooling Limit

Context: Cold-water immersion is recommended for the immediate field treatment of exertional heat stroke. However, concerns exist over potential overcooling of hyperthermic individuals during cold-water immersion. Objective: To evaluate the recommendation that removing previously hyperthermic individuals from a cold-water bath at a rectal temperature (Tre) of 38.6°C would attenuate overcooling. Design: Controlled laboratory study. Setting: University research laboratory. Patients or Other Participants: Participants included 6 men and 4 women (age = 22 ± 3 years, height = 172 ± 10 cm, mass = 67.8 ± 10.7 kg, body fat percentage = 17.1% ± 4.5%, maximum oxygen consumption = 59.3 ± 8.7 mL·kg−1·min−1). Intervention(s): After exercising at an ambient temperature of 40.0°C for 38.5 ± 9.4 minutes, until Tre reached 39.5°C, participants were immersed in a 2.0°C circulated water bath until Tre decreased to either 37.5°C or 38.6°C. Subsequently, participants were removed from the water bath and recovered for 20 minutes at an ambient temperature of 25°C. Main Outcome Measure(s): Rectal and esophageal temperatures were measured continuously during the immersion and recovery periods. Results: Because of the experimental design, the overall time of immersion was greater during the 37.5°C trial (16.6 ± 5.7 minutes) than the 38.6°C trial (8.8 ± 2.6 minutes) (t9 = −4.740, P = .001). During the recovery period after cold-water immersion, both rectal (F1,9 = 50.540, P &lt; .001) and esophageal (F1,6 = 20.365, P = .007) temperatures remained greater in the 38.6°C trial than in the 37.5°C trial. This was evidenced by low points of 36.47°C ± 0.70°C and 37.19°C ± 0.71°C for rectal temperature (t9 = 2.975, P = .016) and of 35.67°C ± 1.27°C and 36.72°C ± 0.95°C for esophageal temperature (t6 = 3.963, P = .007) during the recovery period of the 37.5°C and 38.6°C trials, respectively. Conclusions: Immersion for approximately 9 minutes to a rectal temperature cooling limit of 38.6°C negated any risk associated with overcooling hyperthermic individuals when they were immersed in 2°C water.

Size and Density Variation in Microtriches from Bothriocephalus Species Found in Cyprinus Carpio from Lake Powell, UTAH.

Absorption enhancing microtriches of Bothriocephalus sp. were studied in relation to location, size, density, structure, and possible function using SEM.Carp, C. carpio, were collected by gill nets set in Lake Powell, Utah. Tapeworms were collected from the carp intestine and relaxed in a cold water bath for 12 hours, placed in 1% cacodylate buffered glutaraldehyde, washed in a cacodylate buffer, soaked overnight in 1% OsO4, washed in buffer, dehydrated in an ETOH series, critical point dried, attached to stubs, and sputter coated for four minutes with gold. Bothriocephalus was viewed at varying magnifications using the JEOL 6100 scanning electron microscope. Density counts and measurements were conducted using digitized images and the program Semafore. Images were collected from the scolex and 8 equal body sections. Microtriches were measured from the tip to the base.