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Biomedical subjects

T Hildebrandt

Publications and source records attributed to T Hildebrandt.

At least 19 recordsLinked to original sources
PubMed2006

The effect of body condition on ovarian activity of free ranging tropical jennies (Equus asinus).

Serial ultrasonography was performed on seven jennies to study the effect of seasonally fluctuating body condition on ovarian activity during the dry, short rainy and long rainy seasons. Kendall Tau correlations and differences of least square mean values were compared. A distinct seasonal pattern was observed both in body condition and ovarian activity. The mean (+/-SD) Body Condition Score (BCS) was lowest during the dry season 2.6 +/- 0.45 when compared with 3.5 +/- 0.52 and 3.9 +/- 0.58 during the short and long rainy seasons, respectively. The mean (+/-SD) number of total follicles was also proportionally low 7.3 +/- 1.6 during the dry season compared with 9.6 +/- 2.4 and 11.3 +/- 3.3 found during the short and the long rainy seasons, respectively. The BCS was positively correlated to the total number of follicles and the diameter of the largest follicle during all seasons. Periods of increasing BCS and transition between seasons with both increasing and decreasing body conditions were strongly correlated to the number and size of ovarian follicles. Seasonal fluctuation in the body condition was found to be the result of variation in feed resource and ovarian activity was also closely following this seasonal pattern. The improvement in body condition has generally, a positive impact on emergence of small growing follicles there by having influence on the total count of ovarian follicles.

Animals↗
PubMed2004

[Prevalence of anti-Yersinia antibodies in European brown hares in North-Rhine Westphalia, Germany].

Yersinia (Y.) pseudotuberculosis infections may lead to significant lethality in European brown hare (Lepus europaeus, Pallas) populations especially during the cold and wet seasons. In recent decades, also Y. enterocolitica was isolated from hares found dead. Consequently, a Western-blot technique proved to be valuable for the detection of antibodies against all pathogenic Yersinia isolates was applied to monitor the prevalence of antibodies in hare populations in North-Rhine Westphalia, Germany. A total of 89.6% of the 230 animals tested was seropositive. Further investigations should be performed to elucidate the role of subclinical yersiniosis in the decline of European brown hare populations in Germany.

Animals↗
PubMed2001

Dispersion and damping of a two-dimensional plasmon in a metallic surface-state band.

We have studied, for the first time, the energy and the linewidth dispersion of a plasmon in a dense two-dimensional electron system in a metallic surface-state band on a silicon surface. As expected from the considerably high effective density and long Fermi wavelength of the system, the plasmon energy dispersion exhibited an excellent agreement with the nearly free-electron theory. However, in a small wave number region below the Landau edge, we have observed an anomalous linewidth dispersion which nearly free-electron theories do not predict.

Journal Article↗
PubMed2001

Demonstration of 2-unsaturated C19-steroids in the urine of female Asian elephants, Elephas maximus, and their dependence on ovarian activity.

Air-borne volatile substances have been demonstrated to signal oestrus, induce ovulation and synchronize ovarian activity in different mammals. An oestrous-related pheromone of the female Asian elephant (Elephas maximus) is known to induce behavioural responses in elephant bulls. Additional data revealed that timing of oestrus in females with close social relationships tends to be synchronized. Therefore, urine from female Asian elephants might be expected to contain luteal phase-dependent volatile substances, which may function as additional chemical signals in this species. The aim of the present study was to identify such compounds and to investigate their pattern of excretion throughout the ovarian cycle. Urine samples were collected three times a week during the follicular phase and one to three times a week during the luteal phase from five adult female Asian elephants from a total of 13 non-conception cycles and one conception cycle, including the first 72 weeks of pregnancy. A simple headspace solid-phase microextraction method has been developed for quantification of urinary volatile substances and analysis was performed by gas chromatography. The comparison of urine collected during the follicular and the luteal phase indicated the presence of two luteal phase-dependent substances. Mass spectrometry was used to identify one substance as 5alpha-androst-2-en-17-one and a second substance as the corresponding alcoholic compound 5alpha-androst-2-en-17beta-ol. The 5alpha-androst-2-en-17beta-ol and -17-one profiles reflected cyclic ovarian activity with clear (10-20-fold) luteal phase increases. Furthermore, measurements of both compounds were correlated positively with the concentration of urinary pregnanetriol and indicated cycle duration (15.1 +/- 1.2 weeks) similar to that obtained from pregnanetriol measurements (15.2 +/- 1.6 weeks). The results demonstrate the presence of two luteal phase-specific steroidal volatile compounds in elephant urine. One of the substances, 5alpha-androst-2-en-17-one, has been demonstrated in human axillary bacterial isolates. The measurement of both volatile substances in elephant urine can be used for rapid detection of the stage of the ovarian cycle, as the analysis can be completed within 2 h.

Androstenes↗
PubMed2001

Control of reproduction with anti-progestin and oestrogens in captive bears.

The aim of this study was to establish new methods for controlling reproduction in bears. Anti-progestins were used to interrupt pregnancies. In two consecutive years, the anti-progestin J956 was administered to 11 female bears (nine Ursus arctos, one Ursus tibethanus, one Tremarctos ornatus) living in zoos. The anti-progestin J956 was given orally (n = 4) or parenterally (n = 12). The anti-progestin was administered alone or in combination with ethinyloestradiol, and before or after embryo implantation. The effects of anti-progestin treatment were determined using ultrasonographic examination of the urogenital tract and by monitoring progesterone concentrations in the blood and faeces. Oral administration of anti-progestin was not successful (successful in 0 of 4); however, in contrast, none of the parenteral treated animals remained pregnant (successful in 12 of 12). Parenteral treatment with J956, with or without ethinyloestradiol, was effective in disrupting pregnancy before implantation (successful in 6 of 6) and after implantation (successful in 6 of 6), but administration one month after implantation (n = 2) resulted in incomplete resorption of the fetuses. In conclusion, the administration of anti-progestins may be a useful method for preventing embryo implantation in captive bears.

Abortifacient Agents↗
PubMed2000

Free-operant performance on variable interval schedules with a linear feedback loop: no evidence for molar sensitivities in rats.

Four experiments examined rats' sensitivity to molar and molecular factors on instrumental schedules of reinforcement. Rats were exposed to a variable interval schedule with a positive feedback loop (VI+), such that faster responding led to a shorter interreinforcement interval. In Experiments 1 and 2, rats responded faster on a variable response (VR) schedule than on either a VI schedule matched for reinforcement rate or a VI+ schedule matched for the feedback function. In Experiment 3, rats responded no differently on a VI schedule than they did on a VI+ schedule with equated rates of reinforcement. In Experiment 4, rats responded faster on a VI+ schedule with an interresponse time requirement yoked to that experienced on a VR schedule, than on a VI+ schedule with the same feedback function as the VR schedule. Taken together these results suggest that rats are more sensitive to the molecular than the molar properties of the schedules.

Animals↗
PubMed1999

Novel endotheliotropic herpesviruses fatal for Asian and African elephants.

A highly fatal hemorrhagic disease has been identified in 10 young Asian and African elephants at North American zoos. In the affected animals there was ultrastructural evidence for herpesvirus-like particles in endothelial cells of the heart, liver, and tongue. Consensus primer polymerase chain reaction combined with sequencing yielded molecular evidence that confirmed the presence of two novel but related herpesviruses associated with the disease, one in Asian elephants and another in African elephants. Otherwise healthy African elephants with external herpetic lesions yielded herpesvirus sequences identical to that found in Asian elephants with endothelial disease. This finding suggests that the Asian elephant deaths were caused by cross-species infection with a herpesvirus that is naturally latent in, but normally not lethal to, African elephants. A reciprocal relationship may exist for the African elephant disease.

Africa↗
PubMed1998

Analysis of parotid and mixed saliva in Roe deer (Capreolus capreolus L.).

In ruminants, different functions have been ascribed to the different salivary glands according to the feeding type. In this context, possible adaptations of salivary functions were investigated regarding the secretion of various proteins by different types of salivary glands. To yield uncontaminated parotid saliva in large quantities, a non-surgical method has been developed. Parotid gland secretions were collected via endoscopic placement of guide wires into each parotid duct, which were subsequently used for placement of collection catheters. Salivary flow was stimulated by intra-glandular administration of the parasympathomimetic compound pilocarpine-hydrochloride into the parotid gland. Mixed saliva (excluding parotid saliva) was collected into sterile tubes by normal outflow during the sampling of parotid saliva. The total flow volume, flow rate and the content of proteins as well as of several ions (Na+, K+, Ca2+, inorganic phosphate) of both types of saliva were measured in sheep, fallow deer and roe deer. Roe deer secreted the highest amount of total salivary proteins relative to body mass [mg/kg body mass] and the highest relative volume [ml/10 min/kg body mass], both in parotid and mixed saliva, of all ruminant species examined. Additionally, the protein profile and the tannin-binding properties of parotid and mixed saliva in roe deer were investigated. Parotid saliva bound almost twice as much tannin as mixed saliva, underlining the importance of yielding uncontaminated parotid saliva for tannin-binding studies.

Adaptation, Physiological↗
PubMed1997

Transrectal ultrasonographic examination of the female urogenital tract in nonpregnant and pregnant captive bears (Ursidae).

The development of reliable methods for monitoring the reproductive cycle of bears is needed to optimise breeding management in captivity. The aim of the present study was to develop non-invasive procedures for obtaining basic data on the reproductive status of nonpregnant and pregnant bears. Eight female captive bears (five Ursus arctos arctos, two Tremarctos ornatus and one Melursus ursinus) were examined using transrectal adaptor ultrasonographic imaging. Plasma concentrations of progesterone and gestagens in faeces were determined simultaneously. The ultrasonographic appearance of the female urogenital tract was assessed during the nonbreeding season and verified in four adult bears post mortem. Pregnant bears were examined twice, as the reproductive physiology of bears is characterized by delayed implantation and pseudopregnancy. During embryonic diapause there was no difference between pseudopregnant and pregnant bears both by ultrasonographic imaging and endocrinological data. After implantation (early December) the pregnancies were visualised by ultrasonographic imaging, whereas plasma concentrations of progesterone and gestagens in faeces had not yet increased. In conclusion, both transrectal ultrasonographic imaging and gestagen monitoring in faeces are efficient methods for obtaining important data on reproduction in bears.

Animals↗
PubMed1996

[Mucociliary clearance of radically operated maxillary sinuses and effect of endoscopic ethmoid bone revision on the mucociliary system].

Twenty-six maxillary sinuses (of 20 patients) were studied following Caldwell-Luc procedures. Surgery had been performed between 1 to 27 years previously. Follow-up studies included nasal endoscopy, coronal computed tomography and camera-sequence scintigraphy. Findings demonstrated that normalization of disturbed mucosal function was possible after surgery. Indications for revision endoscopic sinus surgery are discussed, as are the limitations of surgery.

Ciliary Motility Disorders↗
PubMed1990

[Fractures of the head of the tibia. Evaluation of an East German multicenter study 1981-1985].

The successful therapy of fractures of caput tibiae has always been the "haut ecol" of every treatment of fractures. A study made by 52 surgical clinics of the GDR which examined 1,954 patients who were under medical therapy between 1981 to 1985 summarizes the results. The patients have been examined for a period of 4.5 years in average. The study comparing the results of conservative and surgical medical therapy shows that there is no difference between the results of both methods of medical therapy regardless whether all kinds of fractures or whether only the same kinds of fractures were compared. Even if we consider the impression-fractures we come to the same result although we were of the opinion up to now, that impression-fractures should be treated in a surgical way only. The results of the study make clear the necessity of a strong indication for a surgical treatment and also that an early functional conservative therapy has the same results.

Adult↗