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PubMed1988

Embryonic temperature determines adult sexuality in a reptile.

Gonadal differentiation in amniote vertebrates is controlled by one of two mechanisms: genotypic sex determination (GSD) or environmental sex determination (ESD). After differentiation the fetal gonad produces sex steroid hormones which govern the development of other components of sexuality. Thus, the primary sex determiner is thought to operate solely as a trigger that initiates a cascade of events culminating in adult sex differences. In the leopard gecko (Eublepharis macularius), gonadal and morphological sex is determined by incubation temperature, with relatively 'hot' temperatures (32 degrees C) resulting in mostly male offspring and relatively 'cold' temperatures (26 degrees C) resulting in only female offspring. We report here that the reproductive behaviour and endocrine physiology of an adult is influenced by the temperature experienced as an embryo. Also, the perception of a female to courtship by a male is influenced by incubation temperature. These data indicate that incubation temperature, the primary determiner of sex in this species, has differential effects on adult sexuality.

Animals↗
PubMed1986

Orphenadrine citrate increases and prolongs the antinociceptive effects of paracetamol in mice.

Orphenadrine, a muscle relaxant with antinociceptive effects, was shown to increase and prolong the antinociceptive effects of paracetamol in mice. Both in the increasing temperature hot plate test and in the formalin test, a combination of the two drugs showed a significantly improved effect compared to either of the drugs alone. The time course of the effects was tested in the increasing temperature hot plate test. The group treated with the drug combination showed a prolonged effect compared to both single drug treated groups, the effect lasting longer than 120 min. for the combination and about 80 min. for the single drugs. Orphenadrine and paracetamol increased antinociception even when orphenadrine was injected 90 min. after paracetamol, which by that time did not exert antinociceptive effects by itself. Thus the combination of orphenadrine and paracetamol enhances the antinociceptive effect of either drug in mice.

Acetaminophen↗
PubMed1987

The effect of diazepam on nociception in mice.

The antinociceptive properties of diazepam were evaluated in mice, using four different pain tests and different doses of the drug (0.2, 0.5, 1.0 and 2.0 mg/kg). In the tail flick test and the increasing temperature hot plate test there were no effects. In the formalin test reduced licking was observed for the highest dose of diazepam. However, this dose also induced clear sedation possibly causing the reduced licking response. In the constant temperature hot plate test a hyperalgesia was found for all doses tested. This hyperalgesia was not observed in animals adapted to the test apparatus, suggesting that the "hyperalgesic" effect of diazepam may be due to reduced stress analgesia. The serum concentrations of the drug were comparable to therapeutic levels in humans. It was concluded that the sedative and anxiolytic effects of diazepam may influence the results of nociceptive tests, but the drug has probably no effect on nociception in itself.

Analgesics↗
PubMed1987

Involvement of central serotonergic pathways in nefopam-induced antinociception.

The possible involvement of central serotonergic pathways in the mechanism of action of nefopam was investigated in male albino mice. Nefopam (15 mg/kg i.p.) did not alter the concentration of serotonin or its metabolite 5-hydroxyindole acetic acid in frontal cortex or spinal cord. Lesions of the ascending serotonergic pathways were made by systemic administration of p-chloroamphetamine (PCA). Serotonin depletion in all serotonergic systems was obtained by means of p-chlorophenylalanine (PCPA). Two different nociceptive assays were used, the formalin test and the increasing temperature hot plate test. PCPA pretreatment significantly reduced the effect of nefopam (15 mg/kg) in the formalin test. In contrast, nefopam-induced analgesia was not affected by PCA pretreatment, either in the formalin test or in the increasing temperature hot plate test. In conclusion, the data suggest that descending serotonergic pathways are involved in nefopam-induced antinociception.

Analgesics↗
PubMed1976

Effect of temperature-season on bovine adrenal cortical function, blood cell profile, and milk production.

Data collected monthly for one calendar year from Holstein cows lactating under Louisiana ambient climatic conditions comprised a total of 264 cow-months. The year was divided into seasons of cool, intermediate, and hot temperatures. The hot season elicited depressions in circulating corticoids and percent hematocrit. Leukocytosis was a response to increasing ambient temperature primarily accounted for by an increase in circulating neutrophils. Progression from intermediate to hot season gave evidence of eosinophila, and in addition, a relative eosinopenia may have been induced by increased adrenal cortex activity. Milk production was depressed during the hot temperature-season and showed no significant relationship with corticoids of plasma. Rectal temperatures and respiration rates were indicative of heat stress in the hot temperature-season and gave significant negative correlations with circulating corticoid concentration.

Adrenal Cortex↗
PubMed1985

Minimum temperature felt as hot (MTH)--a new concept for grading the loss of temperature sensation in leprosy patients.

In order to grade the loss of the temperature sensation in the skin of leprosy patients, a newly designed instrument called the Temperature-Sensation-Testing-and-Grading device has been employed to determine the minimum temperature felt as hot (MTH) at the skin area. The MTH in normal subjects was observed to vary from one region of the body to another; it was generally higher on the distal parts of the extremities compared to the proximal parts; and it was also higher on the lower extremities compared to the upper ones. The abdomen and the back generally had the lowest values. There were no variations according to age (11-80 years) or sex and no differences on symmetrical sites of the body. The MTH value, however, showed a dependence on the environmental temperature, the values being lower at low environmental temperatures and higher at high environmental temperatures. But at the same site and the same environmental temperature, the MTH value was found to be almost constant. Different individuals had different MTH values at the same body site and even at the same environmental temperature. The unaffected skin of leprosy patients showed values comparable to the controls. At the leprosy lesions, however, the degree of sensory loss could easily be determined in comparison with the MTH at the contralateral/adjoining unaffected skin. Out of 54 leprosy patients, 7 patients had no sensory loss; in 27 patients the loss varied between 1 degree C and 20 degrees C; while in 20 patients the loss was complete--they could not perceive even 50 degrees C as hot.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1975

Quantification of the analgesic activity of narcotic antagonists by a modified hot-plate procedure.

The analgesic activity of morphine and the narcotic antagonists, pentazocine, cyclazocine, levallorphan and nalorphine, was assessed in the rat using two hot plates: one maintained at 49.5 degrees C and the other at the "standard" 54.5 degrees C. The analgesic effects of morphine using the 49.5 degrees C hot plate were of a significantly greater magnitude than its effects using the 54.5 degrees C hot plate for both nontolerant and morphine-tolerant subjects. Dose-related effects were observed with all of the narcotic antagonists tested using the 49.5 degrees C hot plate; only the highest dose of pentazocine exhibited activity using the 54.5 degrees C hot plate. Naloxone (3.0 mg/kg) antagonized the analgesic effects of morphine and all of the narcotic antagonists, but was without activity itself when tested using the 49.5 degrees C hot plate at doses as high as 30 mg/kg. Aspirin was also inactive using the 49.5 degrees C plate, whereas physostigmine increased latencies only at a dose that produced severe motor deficit. A low temperature hot plate is recommended for evaluating the analgesic activity of narcotic antagonists in the rat. This simple procedure provides results which are dose-related, quantifiable, reproducible, of a large magnitude and specific.

Analgesia↗
PubMed1975

Efficiency and loading characteristics of EPA's high-temperature quartz fiber filter media.

It was experimentally demonstrated that Gelman Type A and "Microquartz" filters are efficient collectors of nonvolatile particles at high temperatures. Submicron particles penetrated more than large particles, and most at the highest filtration velocity tested of 51 cm/sec. In all tests, however, aerosol penetration was never more than about 0.10%. Nonvolatile particles penetrated less with increasing temperature filter loading. Particles with vaporization points below the sampling temperature, including H2SO4, can vaporize, pass through the glass fiber filters, and then recondense when cooled below their dew points. Therefore, the definition of "particulate matter" must be based upon a prescribed temperature. Hot stack gases, sampled at different filter temperatures, should not necessarily be comparable. Particulate emission standards must involve a suitable reference temperature to allow proper enforcement. Filtration efficiencies calculated by theoretical equations change dramatically with small changes in assumed average filter fiber diameter and/or particle size (or size distribution) used in the calculations. Pinholes not visible to the naked eye do not appear to effect penetration of glass fiber filters enough to significantly alter stack sampling results. Effect of temperature on filtration of non-volatile particles simply resulted in an increasing collection of submicron particles with increasing temperature. The main problems encountered at elevated temperatures were vaporization of volatile particles and mechanical leakage of the filter holder.

Environmental Health↗
PubMed1988

Body temperature and grooming in the Mongolian gerbil.

The Mongolian gerbil, Meriones unguiculatus, like many other rodents, releases a complex mixture of pigments and lipids from the Harderian gland during a self-groom. The material exits from the external nares of the nose, is mixed with saliva, and spread widely over the pelage. Cold temperatures, especially, are effective in initiating grooming. A self-groom is associated with an increase in body temperature (compensatory thermogenesis in the cold). In addition to acting as a chemosignal, the Harderian material serves two major homeostatic functions: (1) the lipids on the pelage act to insulate the animal against cold and wetness, and (2) the lipids and pigments darken the pelage and increase radiant absorption. Body temperature is thus maintained at a higher level than would otherwise be the case. The amount of Harderian material found on the pelage varies with Harderianectomy, sandbathing, and ambient temperatures. Animals prevented from sandbathing accumulate excess lipids on the pelage, and cold temperatures facilitate the acquisition of lipids on the pelage. Under hot temperatures the grooming of Harderian substances is repressed and the frequency of sandbathing is increased. Thus pelage lipids are reduced in two ways. The amount of Harderian material released during an autogroom is inversely related to the ambient temperature, whereas the amount of saliva used for evaporative cooling is positively related to ambient temperature. The net effect is that pelage lipids are increased and maintained during cold conditions, and are reduced during hot conditions. In hot environments the gerbil switches from the spread of Harderian material for insulation to the spread of saliva for evaporative cooling. The gerbil optimizes its body temperature by varying the frequency of grooming and sandbathing, and by altering the amount of Harderian material and saliva released. Other species living in arid environments may use similar mechanisms to stabilize body temperature. Self-grooming is a critical behavior for meeting thermal needs, and is complexly integrated with related processes.

Adaptation, Physiological↗
PubMed1987

Temperature and aggression: effects on quarterly, yearly, and city rates of violent and nonviolent crime.

The hypothesized relation between uncomfortably hot temperatures and aggressive behavior was examined in two studies of violent and nonviolent crime. Data on rates of murder, rape, assault, robbery, burglary, larceny-theft, and motor vehicle theft were gathered from archival sources. The first three crimes listed are violent; the latter four are less violent (labeled nonviolent). On the basis of previous research and theory (Anderson & Anderson, 1984), it was predicted that violent crimes would be more prevalent in the hotter quarters of the year and in hotter years. Furthermore, it was predicted that this temperature-crime relation would be stronger for violent than for nonviolent crime. Study 1 confirmed both predictions. Also, differences among cities in violent crime were predicted to be related to the hotness of cities; this effect was expected to be stronger for violent than for nonviolent crimes. Study 2 confirmed both predictions, even when effects of a variety of social, demographic, and economic variables were statistically removed. Theoretical and practical implications are discussed.

Aggression↗
PubMed1992

Desipramine, administered chronically, influences 5-hydroxytryptamine1A-receptors, as measured by behavioral tests and receptor binding in rats.

The 5-hydroxytryptamine1A (5-HT1A) receptor subtype seems to be of importance in the pathogenesis of depression and in the mode of action of antidepressants. In this study, behavioural experiments were performed in rats after oral administration of desipramine for 18-20 days, followed by an acute injection of the selective 5-HT1A receptor agonist, 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT), either systemically or intrathecally. Chronic administration of desipramine prolonged the behavioural 5-HT syndrome in the animals injected systemically with 8-OH-DPAT. Treatment with desipramine was also found to potentiate and prolong the antinociceptive effect of an acute injection, systemically or intrathecally, of 8-OH-DPAT in the increasing temperature hot plate test. After systemic administration of 8-OH-DPAT, the colonic temperature was lowered similarly in the desipramine-treated group and in controls, whereas an intrathecal injection of 8-OH-DPAT resulted in a fall in the colonic temperature in the desipramine-treated group only. In vitro receptor binding studies, using [3H]8-OH-DPAT as the ligand, showed a statistically significant reduction of Kd and Bmax in the frontal cortex and of Kd in the spinal cord, after treatment with desipramine. No changes of Kd and Bmax were found in the hippocampus after this treatment. Thus, desipramine, administered chronically, resulted in a functional up-regulation of the 5-HT1A-receptors, both spinally and supraspinally, whereas in the in vitro receptor binding, a slight down-regulation or no change was found. It seems therefore that the results of in vitro receptor binding studies do not necessarily reflect the functional state of the neuronal system.(ABSTRACT TRUNCATED AT 250 WORDS)

8-Hydroxy-2-(di-n-propylamino)tetralin↗
PubMedDate not supplied

The influence of tissue layering on microwave thermographic measurements.

Non-invasive thermal imaging and temperature measurement by microwave radiometry has been investigated for medical diagnostic applications and monitoring hyperthermia treatment of cancer, in the context of heterogeneous body structure. The temperature measured by a radiometer is a function of the emission and propagation of microwaves in tissue and the receiving characteristics of the radiometric probe. Propagation of microwaves in lossy media was analysed by a spectral diffraction approach. Extension of this technique via a cascade transmission line model provides an efficient algorithm for predicting the field patterns of aperture antennas contacting multi-layered tissue. A coherent radiative transfer analysis was used to relate the field pattern of a radiating antenna to its receiving characteristics when used as a radiometer probe, leading to a method for simulating radiometric data. Measurements and simulations were used to assess the effect of overlying fat layers upon radiometer response to temperature hot spots in muscle-type media. Results suggest that dielectric layering in tissue greatly influences measured temperatures and should be accounted for in the interpretation of radiometric data.

Fats↗
PubMed1989

The apparent hyperalgesic effect of a serotonin antagonist in the tail flick test is mainly due to increased tail skin temperature.

It has been suggested that reduced activity in raphe-spinal serotonergic systems induces hyperalgesia. In rats, the serotonin antagonist metergoline (0.5 mg/kg intraperitoneally) reduced tail flick latency by 0.92 sec (p less than 0.001) and increased tail skin temperature by 2.4 degrees C (p less than 0.001) when measured 50 min after injection. Multiple regression analysis with tail flick latency as dependent variable and tail skin temperature and metergoline/vehicle as independent variables revealed a highly significant effect of tail temperature on tail flick latency. The increase of tail skin temperature explained a reduction of tail flick latency of 0.64 of the 0.92 sec observed [B = -0.267 +/- 0.034, t(37)= -7.75, p less than 0.0001]. When the effect on tail skin temperature was taken into account, metergoline reduced tail flick latency by 0.28 sec [B = -0.284 +/- 0.114, t(37) = -2.50, p less than 0.05]. Metergoline (0.5 and 2.0 mg/kg) did not significantly alter plantar paw skin temperature or the response temperature in the increasing temperature hot plate test. Thus, the observed effect of metergoline on tail flick latency is primarily due to an effect on tail skin temperature. The possibility exists that the remaining effect of metergoline may be due to inadequate correction for the skin temperature change, and it is concluded that the study provide no clear evidence for a tonic inhibition of nociception by serotonergic systems.

Animals↗