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Biomedical subjects

P Fritzsche

Publications and source records attributed to P Fritzsche.

At least 19 recordsLinked to original sources
PubMed2005

Indicators for post-surgery recovery in Mongolian gerbils (Meriones unguiculatus).

Telemetric investigations of various parameters are widely used to estimate an animal's state. However, the implantation of the transmitters includes anaesthesia and surgery and has short and longer lasting impacts on the studied object. The aim of the present paper was to evaluate these effects in Mongolian gerbils, namely the hypothermia caused by the anaesthetic and the enduring disturbance of daily rhythmicity until complete recovery. The surgery associated with the implantation of the transmitters differed both in severity and type of anaesthesia. Whereas normal values of body temperature were restored within hours, restoration of daily rhythm required several days, depending on the severity of the surgical procedure. Also, the sensitivity of the body temperature to activity changes was different until the rhythms were re-established. A method based on the rhythm magnitude and shape was proposed to estimate the time until complete recovery of the animals.

Anesthetics, Inhalation↗
PubMed2002

Comparative studies of body mass, body measurements and organ weights of wild-derived and laboratory golden hamsters (Mesocricetus auratus).

All laboratory golden hamsters originate from a sibling pairing back in 1930. To investigate possible differences between domesticated and wild conspecifics, descendants of both strains were maintained under standardized laboratory conditions individually and in unisexual groups. Body mass and food consumption were monitored from birth to 22 weeks of age. The animals were subsequently sacrificed, and body measurements and body composition were analysed. In addition, the absolute and relative masses of different organs were measured. Laboratory hamsters gained more body mass through higher food consumption. However, they did not get fatter, since relative fat values were the same for both strains. Body measurements revealed only minor differences (in body and ear lengths). As deducible from the body mass, the organs (spleen, kidneys, adrenal glands, testes, epididymis and ovaries) were seen to be heavier in laboratory hamsters. Furthermore, with the exception of the kidneys, the same went for the relative values. There were distinct sexual specific differences in both strains only for body fat ( male symbol male symbol upward arrow ) and adrenal glands ( male symbol male symbol upward arrow ). In females, group housing induced an elevated level of aggression. In general, these housing conditions led to social stress symptoms, such as heavier adrenal glands. Additionally, spleen, kidneys, ovaries, body length and mass, body water and body fat were increased in group-housed hamsters. In conclusion, no major differences between laboratory and wild-derived hamsters were observed.

Animals↗
PubMed2001

Activity rhythms of wild and laboratory golden hamsters (Mesocricetus auratus) under entrained and free-running conditions.

The golden hamster (Mesocricetus auratus) is one of the most frequently used laboratory animals, particularly in chronobiological studies. One reason is its very robust and predictable rhythms, although the question arises whether this is an inbreeding effect or rather is typical for the species. We compared the daily (circadian) activity rhythms of wild and laboratory golden hamsters. The laboratory hamsters were derived from our own outbred stock (Zoh:GOHA). The wild hamsters included animals captured in Syria and their descendants (F1). Experiments were performed under entrained (light: dark [LD] 14h:0h) and under free-running (constant darkness, DD) conditions. Locomotor activity was recorded using passive infrared detectors. Under entrained conditions, the animals had access to a running wheel for a certain time to induce additional activity. After 3 weeks in constant darkness, a light pulse (15 min, 100 lux) was applied at circadian time 14 (CT14). Both laboratory and wild hamsters showed well-pronounced and very similar activity rhythms. Under entrained conditions, all hamsters manifested about 80% of their total 24h activity during the dark portion of the LD cycle. The robustness of the daily rhythms was also similar. However, interindividual variability was higher in wild hamsters for both measures. All animals used the running wheels almost exclusively during the dark portion of the LD cycle, although the wild hamsters were three times more active. The period length, measured in constant darkness, was significantly shorter in wild (23.93h +/- 0.10h) than in laboratory hamsters (24.06 +/- 0.07h). The light-induced phase changes were not different (about 1.5h). In summary, these results indicate that the laboratory hamster is not much different from the wild type.

Activity Cycles↗
PubMed2000

Effects of social stress on behavior and corpus luteum in female golden hamsters (Mesocricetus auratus).

The consequences of group-keeping as a social stressor on the solitary-living golden hamster were studied. Two females at the same stage of the estrous cycle were kept together for 5 weeks. Behavioral observations showed that the dominance structures within groups were unstable. Intensity of aggression was highest at metestrous, whereas the greatest activity was observed during the estrous stage. After 1 week, the body masses of singly kept and group-kept hamsters were different. Five weeks after the onset of the experiment, the body mass of the singly kept hamsters had increased by 3.6%, and that of the group-kept hamsters by 25%. The plasma progesterone level of group-kept females was 60 to 70% higher than that of singly kept females. The absolute masses of the adrenal glands and the ovaries were higher in group-kept females. Nevertheless, the relative masses did not differ. Whereas a significant positive correlation between the weights of both organs and the body mass was observed in singly kept females, in group-kept females such a correlation was only observed between body and ovary weight. Number and size of corpora lutea were enlarged in group-kept individuals, and this seems to be responsible for elevated plasma progesterone titres. These results indicate social stress in group-kept female hamsters.

Adrenal Glands↗
PubMed1987

Complex and simple renal cysts: comparative evaluation with MR imaging.

Magnetic resonance (MR) imaging was performed in two groups of patients to determine its usefulness in evaluating fluid-containing renal masses deemed complex with computed tomography (CT). Twenty-two patients in group 1 had indeterminate renal masses by CT, five of which were also indeterminate by ultrasound (US). The results in this group were compared with histologic findings. Group 2 consisted of 20 patients with simple renal cysts diagnosed according to rigid CT criteria. On MR imaging, 11 of the 23 masses in group 1 and 19 of the 20 in group 2 were diagnosed as benign cysts. Fluid within the cyst had long T1 and T2, resulting in a low signal intensity on T1-weighted images. In the 12 remaining lesions in group 1 and in one lesion in group 2, the fluid content was indeterminate and MR did not permit differentiation of cystic renal carcinoma from old hemorrhage or adenoma. When fluid within the cystic mass did not have the MR characteristics of simple fluid, MR was not helpful in characterizing the mass, but when the fluid intensity was similar to normal urine, the cyst was benign.

Adenoma↗
PubMed1986

Glucose-6-phosphate-dehydrogenase (G6PDH) activity in the liver of golden hamsters--its dependence from estrous cycle and consequences on planning experiments.

Glucose-6-phosphate-dehydrogenase activity in the liver of female golden hamsters being in various stages of the estrous cycle were investigated. Animals of the pro- and diestrous stage showed a significantly higher activity than those of the met- and estrous stage. The interpretation of the results in test series has to consider this fact. Possibilities for it have been discussed.

Animals↗