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Biomedical subjects

D Thiessen

Publications and source records attributed to D Thiessen.

9 recordsLinked to original sources
PubMed1991

Lipopolysaccharide increases ambient temperature preference in C57BL/6J adult mice.

The hypothesis was tested that animals exposed to a potentially dangerous endotoxin would attempt to behaviorally elevate their body temperature, perhaps in an effort to engage those immunological mechanisms which would counter the adverse effects of the endotoxin. Lipopolysaccharide (LPS) from Escherichia coli injected subcutaneously (100 micrograms) in adult C57BL/6J mice increased gradient temperature preference by 2.4 degrees C over saline controls. The increase in body temperature of 1.1 degrees C after LPS injection was due to the preference for higher ambient temperatures and was not the result of a systemic reaction to LPS (animals not exposed to the gradient did not differ in body temperature). In summary, our data indicate that adult mice self-induce a febrile response, perhaps as an attempt to compensate for the physiological impact of the endotoxin.

Animals↗
PubMed1991

The effects of odors from stressed mice on conspecific behavior.

Four experiments correlate conspecific reactions to odors from stressed (foot shocked) BALB/cJ mice with the frequency of specific motor activities and taste avoidance. Where behavior was restricted to forward and backward movement in a tube, animals tended to avoid the side where the odors from stressed animals entered. In a more socially complex home cage (3 recipients) a wide variety of behaviors were affected by odors from stressed conspecifics. Animals were alerted by the odor, searched out the source of the odor and showed increases in general activity, rearing, and air sampling. Many of these behaviors habituated with continuous exposure. The major response to odors from stressed animals was to increase "vigilance." A restriction of behavioral opportunities will lead to odor avoidance; however, when the environment permits, the behavioral reaction to odors becomes more complex. These odors failed to produce conditioned taste aversion, suggesting a sensory specificity in the use of these odors.

Animals↗
PubMed1991

Phlebotomy reverses the hemodynamic consequences of thoracic aortic cross-clamping: relationships between central venous pressure and cerebrospinal fluid pressure.

In dogs (n = 11) anesthetized with sodium pentobarbital (to an isoelectric EEG), the authors investigated the influence of thoracic aortic cross-clamping (AXC) on systemic hemodynamics and cerebrospinal fluid pressure (CSFP) with concurrent measurement of total brain flow (tCBF) and regional (cervical, thoracic, and lumbar) spinal cord blood flow (SCBF). The effect of phlebotomy (to control the hemodynamic consequences of AXC) on tCBF and SCBF was assessed. Radioactive microspheres were injected at four time periods in each animal: 1) at baseline; 2) with application of the AXC; 3) after phlebotomy, to reduce the proximal mean arterial pressure (MAPp) to baseline values; and 4) 2 min after removal of the AXC (mean AXC time 68 +/- 6 min). With application of the AXC, the MAPp, central venous pressure (CVP), and CSFP significantly increased (104 +/- 6 to 156 +/- 6 mmHg, 3.4 +/- 0.4 to 5.2 +/- 0.7 mmHg, and 3.3 +/- 0.7 to 5.2 +/- 0.8 mmHg, respectively), while distal mean aortic pressure (MAPd) significantly decreased (98 +/- 6 to 14 +/- 1 1 mmHg). Phlebotomy (24 +/- 3 ml.kg-1) significantly decreased MAPp (to 106 +/- 6 mmHg), CVP (to 1.6 +/- 0.6 mmHg), and CSFP (to 1.2 +/- 1.1 mmHg). The CSFP changed in parallel with the changes in CVP, a result suggesting that the alterations in CSFP depended on cardiac preload. The spinal cord perfusion pressure (SCPP; SCPP = MAPd - CSFP) was unchanged after phlebotomy, since both MAPd and CSFP decreased. The tCBF and cervical SCBF were unchanged when MAPp increased by 50% with application of the AXC; this indicated that autoregulation was intact.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

The use of a sociobiological questionnaire (SQ) for the assessment of sexual dimorphism.

A sociobiology questionnaire (SQ) (Thiessen and Kittrell, 1980) was administered to 527 undergraduate males and females. Twenty-seven predictions were tested. Sixteen of the predictions were statistically confirmed, and eight were in the expected direction. Overall, females appeared to be more interested in their mate's success than their own and were more selective in the choice of mates. Males gave more evidence of competitiveness and tended to mate polygamously. The results are compatible with theoretical expectations about mating strategies (Buss, 1987; Rushton et al., 1984; Thiessen and Gregg, 1980). A number of problems with regard to the application of sociobiological and sociocultural theories to human behavior are discussed.

Adolescent↗
PubMed1989

The possible interaction of Harderian material and saliva for thermoregulation in the Mongolian gerbil, Meriones unguiculatus.

Self-grooming in Meriones unguiculatus is associated with saliva spread and the release and spread of Harderian material from the external nares. Saliva spread results in evaporative cooling and Harderian spread insulates the pelage. Two experiments tested the predictions that (1) saliva production and Harderian material decrease systematically following a self-groom, (2) high ambient temperature (34 degrees C) increases saliva production but decreases Harderian release, and (3) low ambient temperature (7 degrees C) decreases saliva production but increases Harderian release. The predictions were generally confirmed, suggesting that short-term and long-term thermoregulatory reactions are differentially affected by ambient temperatures. Thus, an animal will tend to emphasize saliva production when evaporative cooling is needed and will exaggerate Harderian release when insulation of the pelage is required.

Animals↗
PubMed1989

Ventral marking in the male Mongolian gerbil reflects present and future reproductive investments.

Ventral scent-marking in the male Mongolian gerbil, Meriones unguiculatus, may be related to reproductive potential. In four experiments involving nine groups, males' marking during 5-min. open field tests correlated with their social and reproductive status. The lowest levels of marking occurred among individually housed or subordinate males of a pair, followed by males exposed to ovariectomized females, and dominant males of a pair. Higher levels of marking occurred with vasectomized males living with intact females or following the removal of males from a nuclear family. The most frequent marking occurred when males were housed with pregnant females and with females and their offspring. The proximate stimuli leading to high marking appear to be the sexual availability of reproductively competent females.

Animals↗
PubMed1971

Behavioral genetics.

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Adaptation, Physiological↗