Body temperature in the mouse,hamster, and rat exposed to radiofrequency radiation: An interspecies comparison

• 1.1.|Colonic temperatures of BALB/c and CBA/J mice, golden hamsters, and Sprague-Dawley rats were taken immediately after exposure for 90 min to radiofrequency (RF) radiation.
• 2.2.|Exposures were made in 2450 MHz (mouse and hamster) or 600 MHz (rat) waveguide exposure systems while the dose rate, specific absorption rate (SAR), was continuously recorded. Experiments were performed on naive, unrestrained animals at ambient temperatures (T_a) of 20 and 30°C.
• 3.3.|Body mass and T_a) were found to be significant factors in influencing the threshold SAR for the elevation of colonic temperature. The threshold SARs at T_a's of 20 and 30°C were respectively: 27.5 and 12.1 W/kg for the BALB/c mouse; 40.7 and 8.5 W/kg for the CBA/J mouse; 8.7 and 0.61 W/kg for the golden hamster; and 1.58 and 0.4 W/kg for the Sprague-Dawley rat.
• 4.4.|The relationship between threshold SAR or SAR for a 1.0°C elevation in colonic temperature vs body mass were linearly and inversely related on a double logarithmic plot. The results of this study suggest that the thermoregulatory sensitivity to RF radiation in these rodent species is heavily dependent on body mass and T_a.

     

A simple technique for estimating operative environmental temperature

• 1.1.|Operative environmental temperature (T_c) is commonly measured using a taxidermic mount consisting of a hollow copper cast of an animal's body covered by the animal's integument. We compare estimates of T_c made using such mounts with those derived from use of painted metal sphere thermometers, which are easier to construct and more rugged than taxidermic mounts.
• 2.2.|Comparison of data for 4 bird species indicates that metal spheres may be acceptable T_c-thermometers for analyses involving multiple measurements over moderately long time-scales (e.g. several hours).
• 3.3.|In this case, positive and negative differences between operative temperature estimated from use of taxidermic mounts and painted spheres tend to compensate and the average difference is usually less than 2°C. This difference is similar to that resulting from postural variation of taxidermic mounts or variation among individual mounts in identical postures.
• 4.4.|Sensitivity analysis indicates that use of painted spheres is unlikely to be an important source of error in estimates of total daily energy expenditure.
• 5.5.|In contrast, use of painted sphere thermometers in analyses involving fewer measurements over shorter-time scales can produce unacceptable discrepancies from values obtained from taxidermic mounts (i.e. up to 6.3°C).

     

Significance of scrotal afferents within the general thermoafferent system

• 1.1.|Switching neurons, in the past referred to as a special scrotal afferent system, intergrate information not only from the scrotum, but from various body areas.
• 2.2.|They are present in male and female rats, as well as in guinea-pigs.
• 3.3.|They are present in midbrain, thalamus, hypothalamus and cortical areas.
• 4.4.|Information processing from the scrotum, is not a special system, but part of the general thermo-and noci-afferent system.
• 5.5.|Switching neurons seem to interact with behavioral, perhaps with autonomic thermoregulatory mechanisms, too.

     

Dehydration does not influence the summer versus winter thermal adaptation changes in rabbits (oryctolagus cuniculus), living in natural photoperiod

• 1.1.|Resting metabolic rate of laboratory rabbits kept indoors is susceptible to seasonal fluctuations and is higher in winter than in summer.
• 2.2.|Thermoneutral zone of rabbits under these conditions may shift downwards in winter and upwards in summer.
• 3.3.|Both of these adjustments in thermoregulation seem to be related to the seasonally changing photoperiod.
• 4.4.|Dehydration does not influence these thermoregulatory adaptive changes.

     

A two-peak circadian system in body temperature and activity in the domestic cat,Felis catus L.

• 1.1.|The body temperature and activity of cats exhibit two-peak patterns during the 24 hr period.
• 2.2.|The two peaks are retained when the temperature and activity are permitted to freerun.
• 3.3.|A third prominent peak appears in the actograms in cats in the main colony, induced by the presence of humans.

     

Diurnal temperature sensitivity of dairy cattle in a naturally cycling environment

• 1.1.|Vaginal temperatures of 15 Bos taurus cattle were monitored for 17 days in daily pens exposed to normal environmental fluctuations.
• 2.2.|Regressions of vaginal temperature on ambient temperature were made for each collection time in the 24 h cycle. Slopes of regressions provided an index of animal sensitivity to environmental temperature.
• 3.3.|Fluctuations in sensitivity occurred throughout the day with positive slopes excepts at 0630 h.

     

Energy metabolism and body temperature in 13 sunbird species (Nectariniidae)

• 1.1. Diurnal cycles of body temperature, T_b, and energy metabolism, M, at different ambient temperatures (T_a: +5 −+ 32°C) were tested in 13 sunbird species from various habitats and of different body masses (5.2–14.2 g) including one of the smallest passerines, Aethopyga christinae.
• 2.2. Resting M-level (night) reaches T_a-dependent mean values of 54% (+5°C) and 49% (+25°C) of activity M-levels (day). Expected level is ca 75%.
• 3.3. Resting metabolic rate of sunbirds lies within the range of theoretically expected values for birds.
• 4.4. Mean linear metabolism-weight regression of the night values follows: M = 0.102 × W^0.712 (M = energy metabolism in kJ/hr and W = body mass in g).
• 5.5. Thermal conductances, T_c, are lower (−24%) than the predicted values. This is caused by a decrease of T_b at low T_a. Mean nocturnal T_c is 3.2 J/g × hr × °C, mean day-time value is 4.3 J/g × hr × °C.
• 6.6. The zone of thermoneutrality is, in most species, within a T_a-range of 24–28°C.
• 7.7. Normal day and night levels of T_b are in the same range as reported for other birds of the same weight class. T_b decreases slightly with falling T_a (partial heterothermia). Lowest recorded T_b was 34.2°C.
• 8.8. No species tested showed any sign of torpor at night, independent of T_a, body mass or habitat origin.

     

Thermal acclimation of metabolism and preferred body temperature in lizards

• 1.1.|The standard metabolic rates (SMRs) and preferred body temperatures (PBTs) of the tropical cordylid Cordylus jonesi and temperature lacertid Lacerta lilfordi were determined following acclimation to constant environmental temperatures of 20 and 30°C.
• 2.2.|Although after 5 weeks the SMRs of Cordylus jonesi and Lacerta lilfordi displayed partial compensations of 20.9 and 10.5%, respectively, their PBTs did not alter over this period. Therefore, acclimation does not maintain complete metabolic homeostasis during either the active or inactive phase of the lizard.
• 3.3.|Cordylus jonesi allowed to thermoregulate behaviourally at their PBT during activity possessed similar SMRs to control animals maintained continually at the same background temperatures, indicating that acclimation state in lizards is determined by the body temperatures experienced while at rest.
• 4.4.|The particular acclimatory problems of animals exhibiting behavioural homeothermy are discussed.

     

Thermoregulation in the cicada Platypedia putnami variety lutea (Homoptera: Tibicinidae) with a test of a crepitation hypothesis

• 1.Measurements of body temperature (T_b) in the field demonstrate that Platypedia putnami var. lutea Davis regulates T_b through behavioral mechanisms.
• 2.Thermal responses (minimum flight temperature 17.3°C, maximum voluntary tolerance-temperature 32.5°C, and heat torpor temperature 44.4°C) of P. putnami var. lutea are related to the altitude of their habitat.
• 3.Water loss rates increase with ambient temperature (T_a). Water loss rates are not significantly different at the extremes of the active T_b range but increase significantly when exposed to elevated T_a.
• 4.Acoustic activity was restricted at 6.7°C T_b range. This is similar to the lower end of the T_b range for singing measured in cicada species that produce sound with a timbal mechanism.
• 5.The use of the wing musculature to produce acoustic signals in P. putnami var. lutea does not increase the T_b range over which the species can call compared to timbal calls produced by other cicada species.

     

Environmental and genetic influences on the thermal physiology of Rana sylvatica

• 1.1.|Intraspecific variation in the thermal physiology of Rana sylvatica was examined.
• 2.2.|Heat and cold tolerances of both adult and larval representatives were determined for animals representing populations from New York, Maryland, Kentucky, Ohio, Michigan and Canada.
• 3.3.|In general, frogs from more northern localities exhibited lower heat tolerances.
• 4.4.|There was no evidence of interpopulational differences in cold tolerance. Similar trends were revealed by larval testing.
• 5.5.|Interpopulational differences among laboratory-reared tadpoles suggests a strong genetic component to Rana sylvatica thermal physiology.

     

Alteration of 5-hydroxytryptophan-induced hypothermia by serotonergic agents in the adult domestic fowl (Gallus domesticus)

• 1.1.|5-Hydroxytryptophan (5-HTP) induced a dose-dependent hypothermia in adult fowls.
• 2.2.|The hypothermic effect of 5-HTP was potentiated by carbidopa, citalopram, additive with (±), (−) and (+) propanolol and antagonised by methysergide and metitepine.
• 3.3.|Cyproheptadine, xylamidine and ketanserin did not antagonised 5-HTP-induced hypothermia.
• 4.4.|The results suggest that the hypothermic effect of 5-HTP in fowls may be mediated mainly via activation of central 5-HT receptors, probably 5-HT₁ receptors.

     

Brain temperature regulation of panting and non-panting pigeons exposed to extreme thermal conditions

• 1.1. Brain (hypothalamic), skin and body temperatures were measured in hand-reared acclimated (Acc, n = 5) and non-acclimated (NAcc, n =7) rock pigeons (Columba livia, mean body mass 237 g) exposed to increasing ambient temperatures (T_a) (30–60°C) and low humidities.
• 2.2. In non-panting Acc birds, brain temperature gradually increased from 40.1 ± 0.4°C at 30°C to 41.2 ± 0.4°C at 60°C T_a. A mean body temperature (T_b) of 41.2 ± 0.2°C was measured at T_a up to 50°C; an increase of 1.1°C was observed at 60°C (T_b 42.2 ±0.6°C).
• 3.3. In Acc panting birds exposed for 2 hr to 60°C, T_hy was 41.9 ± 0.8°C and T_s was somewhat (but insignificantly) higher, i.e., 42.2 ± 0.7°C. It looks as if both values were increased as a result of a slight hyperthermia that developed (T_b = 43.5 ± 0.9°C).
• 4.4. The significance of the present results for evaluating neuronal thermoresponsiveness of birds' hypothalamus is discussed.

     

Thermoreceptor distribution in different skin layers and its significance for thermoregulation

• 1.1.|The activity pattern of 50 cold receptors of the rabbit nose back skin was investigated.
• 2.2.|The latency of the response of individual cold receptors to identical cold stimuli varied between 0.8 ± 0.3 to 29.4 ± 4.5 s; maximal firing rates are attended after 5.5 ± 0.5 to 72.2 ± 6.2 s. Characteristic phasic responses are only demonstrated by short latency receptors.
• 3.3.|The results suggest that cold receptors are distributed throughout the skin of the rabbit's nose.
• 4.4.|Changes of temperature gradients between different skin layers were measured at different ambient temperatures.
• 5.5.|It is suggested that cold receptors might indicate heat flow through the skin.

     

The temperature of the air within the external auditory meatus compared with esophageal temperature during anaesthesia and surgery

• 1.1.|Air temperature within the external auditory meatus, sensed by a thermistor insulated from the walls of the aural canal, was compared with the temperature recorded from a probe in the esophagus in patients under general anaesthesia.
• 2.2.|In the first study of 14 patients, aural temperatures at the time of induction of anaesthesia were more than 3°C lower, and the changes during surgery were more variable, than those recorded from the esophagus.
• 3.3.|In a second study of 35 patients in which heat loss from the external ear was reduced by ear protectors, there was also a poor correlation between temperatures of the ear and esophagus. Aural temperature was initially lower and rose over time in most cases whereas esophageal temperature generally decreased.
• 4.4.|These results suggest that air temperature within the aural canal is not a useful estimate of deep body temperature since it reflects mainly skin temperature.

     

Phosphorylation in crayfish (Procambarus clarkii) eggs during hatching

• 1.1.|The high-energy phosphorylation metabolism in crayfish, Procambarus clarkii eggs during brooding and juvenile crayfish after hatching was studied by in vivo³¹P nuclear magnetic resonance (³¹P NMR) spectroscopy.
• 2.2.|Inorganic phosphoric acid (Pi) and adenosine-5′-triphosphate ATP(γ-,α-,β-) were detected in the dark brownish red eggs after oviposition.
• 3.3.|In orange unhatched eggs, only sugar phosphate (SP), Pi and resolved phosphometabolite from ATP were observed.
• 4.4.|Peaks of SP, Pi, arginine phosphate (Arg-P), and ATP (γ,α,β) appeared in larvae of crayfish after hatching (nauplius, zoea and juvenile crayfish).
• 5.5.|The high-energy phosphorylation metabolism changed to an anaerobic condition along with a decrease in the concentration of dissolved oxygen in fresh water.

     

Populational analysis of thermal responses—I. Changes in the heat resistance of muscle tissue and contractile muscle models of Salamandra salamandra larvae

• 1.1.|Study has been made of the heat resistance of m. rectus superficialis and their contractile models of larvae of 12 families of Salamandra salamandra kept at three different temperatures: 14, 21 (optimal) and 27°C. The heat resistance of the organism has been studied only in larvae kept at 21°C.
• 2.2.|An inverse linear relation has been found between the level of the average heat resistance of muscles for offspring, of the same family, under optimal conditions and its increase caused by a change in environmental temperature. A similar relationship was observed in contractile muscle models. This implies that a population responds to a change in environmental temperature as a function al system.
• 3.3.|The analysis of individual differences in the pattern of response of muscles, and their contractile models, to changes in environmental temperature allows the systemal and individual components to be isolated. The extent of co-ordination in responses of different individuals of the population can be evaluated from the proportion of the systemal component. The value of this component varies from 0.60 to 0.90.
• 4.4.|Selective advantage during thermal selection belongs to individuals with lower heat resistance of muscles.

     

Thermotolerance and thermal sensitization in a differentiating murine erythroleukemia cell line

• 1.1.|Friend erythroleukemia cells (FELC, a differentiating cell line) were heated at various temperatures and heating sequences. Heat treatments which ranged from 41.0 to 45.0°C and did not cause differentiation in FELC and inhibited the differentiation response to DMSO in FELC.
• 2.2.|Heating resulted in cell killing which increased with temperature and heating time. Protracted low temperature heating (40.0–42.0°C) or incubation at 37°C between two heat treatments at 45.0°C resulted in thermotolerance for both the endpoints of cell killing and differentiation.
• 3.3.|High temperature heating (45.0°C) before heating at 41.0–42.0°C resulted in increased thermal sensitivity to the latter heat treatments. This was observed for both the survival and differentiation endpoints.
• 4.4.|A comparison was made of the thermal sensitivity for the two endpoints of cell killing and differentiation.

     

Ascaris suum: Influence of embryonation temperature on the viability of the infective larva

• 1.1.|The infective larvae of Ascaris suum develop in the egg between the temperatures 16 ± 1°C and 34 ± 1°C. Within this temperature range, increases in temperature increase the rate of development. The maximum rate of egg development is attained at 31 ± 1°C.
• 2.2.|Eggs embryonated at 28 ± 1°C and above give rise to infective larvae which have less ability to hatch in vitro, shorter longevity when aged in phosphate buffered saline (pH 7.2) at 37°C, and more limited ability to penetrate tissue membranes in vitro, when compared with those larvae from eggs embryonated at lower temperatures.
• 3.3.|Maximum larval viability and ability to penetrate tissues in vitro was achieved when eggs were embryonated at 22 ± 1°C. These results suggest that the optimal temperature for rate of development and larval viability, or survivability are not the same, a point which has not previously been emphasised.
• 4.4.|The practical significance of these results are discussed in relation to the epidemiology of Ascarias and the known biology of the parasite.

     

Influence of repeated hyperthermia on the early development of carcinogen-induced rat mammary cancers; Refinement of a technique for hyperthermia research

• 1.1.|Hyperthermia (c. 41°C) occurs in mammals (e.g. humans) during normal life-history events such as fever and vigorous exercise. The effects of such episodic hyperthermia on early developmental stages of cancer are of potential importance, yet have been investigated hardly at all.
• 2.2.|We injected female Sprague-Dawley rats with the mammary-gland carcinogen 7,12-dimethylbenzathracene and, over a 4-week period before cancer onset, subjected them to 20 1-h episodes of whole-body hyperthermia (41.2°C colonic) to determine effects on subsequent appearance of carcinomas.
• 3.3.|Hyperthermia did not have significant effects on the development of clinical disease in this system, indicating that precancerous or incipient cancerous cells are not susceptible to damage by the levels of hyperthermia associated with normal life-history events.
• 4.4.|For repeated induction of hyperthermia with minimal confounding effects of stress, we refined a technique in which hyperthermia-treated animals, as well as controls, were anesthetized with sodium pentabarbital during thermal treatments, thus suppressing thermoregulation and higher brain functions.

     

The rate of development in poikilothermic animals calculated in astronomical and relative time units

• 1.1.|The problem of comparing the rate of development of various species of poikilothermic animals, using the astronomical time units and relative units of development duration (in the unit of τ₀ — the duration of one mitotic cycle in the period of synchronous cleavage divisions) is considered, a number of fish and amphibian species is taken by example.
• 2.2.|A dimensionless criterion of the relative rate of development (CRR) is proposed. In closely related animal species and genera in the early development CCR = 1, and only later on do some species begin to develop faster than the others, as it takes them less time (measured in a lesser number of τ₀) to pass the identical developmental periods (τ_n).
• 3.3.|In more distant animal groups the same name but not identical developmental periods have different relative duration from the early stages of development, due to gastrulation beginning at different stages of the blastulation, i.e. as a result of heterochronies.