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Biomedical subjects

K Hildebrandt

Publications and source records attributed to K Hildebrandt.

12 recordsLinked to original sources
PubMed2000

Adult treatment with methamphetamine transiently decreases dentate granule cell proliferation in the gerbil hippocampus.

The objective of the present study was to examine whether acute treatment with the recreational drug methamphetamine influences adult granule cell proliferation in the dentate gyrus of the hippocampus. For that purpose, at the age of postnatal day 90 adult male gerbils (Meriones unguiculatus) received a single dose of either methamphetamine (25 mg/kg; i.p.) or saline. Proliferation of granule cells was identified by in-vivo labeling with 5-bromo-2'-desoxyuridine (BrdU) which was applied either simultaneously with methamphetamine or 36 h after administration of the drug. BrdU-labeled granule cell nuclei were identified in consecutive horizontal slices along the mid-septotemporal axis of the hippocampus and light-microscopically quantified 7 days after the BrdU-labeling. It was found that in both saline- and methamphetamine-treated animals there was a highly significant spatial septotemporal gradient in granule cell proliferation with numbers of BrdU-labeled cells gradually declining from the septal towards the temporal pole. The acute treatment with methamphetamine suppressed granule cell proliferation by about 28% and the septotemporal gradient of mitotic activity became significantly attenuated. It was further found that 36 h after the drug challenge granule cell proliferation rates had been restored almost to the control values along the whole septotemporal axis of the hippocampus. The present results are discussed with regard to (1) pharmacological regulation of neurogenesis in the hippocampus and (2) probable clues they may provide for both understanding the biological correlates of psychotic disorders and evolution of future concepts in neuropharmacological intervention.

Age Factors↗
PubMed2000

Granule cell proliferation and axon terminal degradation in the dentate gyrus of gerbils (Meriones unguiculatus) during maturation, adulthood and aging.

The objective of the present study was to examine both naturally occurring degrading events in axon terminals of the dentate gyrus and granule cell proliferation in the dentate gyrus of gerbils (Meriones unguiculatus) throughout postnatal life. For that purpose, (1) a selective silver staining technique was applied to analyze neuronal lysosome accumulation (LA), indicating synaptic degradation during development. LA was quantified by counting silver grains in the inner third and outer two thirds of the molecular layer, granular layer, subgranular layer and the hilus of the dentate gyrus. (2) Proliferation of granule cells was identified by in-vivo labeling with 5-bromo-2'-desoxyuridine (BrdU). BrdU-labeled granule cell nuclei were identified in consecutive horizontal slices along the mid-septotemporal axis of the hippocampus and light-microscopically quantified 4h after the BrdU-labeling. It was found (1) that in young animals LA significantly increased within all layers and reached adult levels after about 3 months. During subsequent development LA kept on this level throughout aging with highest values within the inner molecular layer. (2) There was a highly significant temporal gradient in granule cell proliferation with numbers of BrdU-labeled cells exponentially declining during juvenile life. Nevertheless, granule cell proliferation occurred throughout adult life and aging. The present results are discussed (1) with concepts of ongoing neuroplasticity and remodeling of neuronal networks in the developing and adult brain, and (2) with regard to pharmacologically induced neuromorphogenesis.

Aging↗
PubMed1999

A single neonatal dose of methamphetamine suppresses dentate granule cell proliferation in adult gerbils which is restored to control values by acute doses of haloperidol.

A single non-invasive dose of methamphetamine (50 mg/kg; i.p.) was administered to neonatal male gerbils (Meriones unguiculatus) aged 14 days. The first objective of the present study was to examine whether this early drug challenge, which has been shown to induce suppressive postnatal maturation of prefrontal dopamine (DA) innervation (Dawirs et al., 1994), interferes with adult granule cell proliferation in the dentate gyrus. Proliferation of granule cells was identified by in-vivo labeling with 5-bromo-2'-desoxyuridine (BrdU). BrdU-labeled granule cell nuclei were identified in consecutive horizontal sections along the mid-septotemporal axis of the hippocampus and light-microscopically quantified 7 days after BrdU-labeling. It was found that a single neonatal dose of methamphetamine was a stimulus strong enough to significantly attenuate adult granule cell proliferation. This effect was clearly lateralized with significant suppression of mitotic activity becoming apparent solely in the left dentate gyrus (-34%). The second objective of the present study was to examine whether acute doses of haloperidol, which have been found to stimulate granule cell proliferation in healthy adult animals (Dawirs et al., 1988), might restore mitotic activity to control values. For that purpose, at the age of postnatal day 90 adult animals which had been challenged with methamphetamine as juveniles received 4 doses of haloperidol (5 mg/kg; i.p.). Proliferation of granule cells was identified by BrdU-labeling. It was found that this neuroleptic treatment acutely restored granule cell proliferation rates to control values. The present results are discussed with regard to (1) factors, regulating mitotic activity in the hippocampus and (2) probable clues they may provide for understanding the neurobiological basis of psychotic behavior.

Aging↗
PubMed1998

Adult treatment with haloperidol increases dentate granule cell proliferation in the gerbil hippocampus.

Male gerbils were bred and reared grouped under enriched semi-natural environmental conditions. The objective of the present study was to examine the influence of an acute treatment with the neuroleptic haloperidol on adult granule cell neurogenesis in the hippocampus. For that purpose, at the age of postnatal day 90 adult animals received 4 challenges of either haloperidol (5 mg/kg, i.p.) or saline. Proliferation of granule cells was identified by in-vivo labeling with 5-bromo-2'-desoxyuridine (BrdU) which was applied 1 hour after the final dose of haloperidol. BrdU-labeled granule cell nuclei were identified in consecutive horizontal slices along the mid-septotemporal axis of the hippocampus and light-microscopically quantified 7 days after the BrdU-labeling. It was found that in both saline- and haloperidol-treated animals there was a highly significant spatial septotemporal gradient in granular cell proliferation with numbers of BrdU-labeled cells gradually declining from the septal towards the temporal pole. The acute treatment with haloperidol stimulated granule cell proliferation by about 75% and the septotemporal gradient of mitotic activity became significantly enhanced. The present results are discussed with regard to known factors regulating cell proliferation in the hippocampus and other cell systems.

Animals↗
PubMed1997

ADP-ribosylation by the extracellular fibrils of Myxococcus xanthus.

The isolated, extracellular fibrils of the myxobacterium, Myxococcus xanthus, are capable of carrying out ADP-ribosylation. The substrate for the ADP-ribosylation is reactive with monoclonal antibody 2105, which has been shown to be directed specifically against the integral fibril proteins. The extracellular fibrils thus contain both the ADP-ribosyl transferase and the substrate for the ribosylation. This process may play a role in the contact-mediated cell-cell interactions that are an important part of the social behaviour of M. xanthus.

Adenosine Diphosphate↗
PubMed1995

[Animal welfare laws concerning air transportation of lobsters and langostinos].

According to scientific understanding the following statements are important to assure a successful transportation of crustaceans. 1. An exact definition of the kind (species) of lobster to be transported is necessary. 2. Providing a humid climate in the containers. 3. Application of ventilation holes of 3 cm size of the container. 4. Rinsing with clean oxygen-containing water of the respiratory apparatus after transportation. 5. Decapodes are not to be transported during 7 weeks after skinning. 6. Through adding of iced water in plastic bags a temperature of +2 degrees C should be created in the container. 7. No shaking during transportation. 8. According to experiences of myself and of that of traders too no more than 4 layers of lobsters may be piled up.

Aircraft↗
PubMed1985

Attributions, expectations, and coping with abortion.

We examined cognitive predictors of coping with a negative life event. Women undergoing first-trimester abortion were, before the procedure, surveyed regarding their attributions for their pregnancy, expectations for coping, the meaningfulness of the pregnancy, and the degree to which the pregnancy was intended. After the abortion and again at a follow-up visit, we assessed affective state, physical complaints, anticipated negative consequences, and depression. As predicted, women who blamed their pregnancy on their character coped less well than low self-character blamers, but contrary to predictions, self-behavior blame was unrelated to coping. Women who had high coping expectations before the abortion coped much better than those with low coping expectations. Women who found their pregnancy highly meaningful, however, coped worse immediately after the abortion than did women who found their pregnancy less meaningful. Intentionality of the pregnancy was related to depression three weeks after the abortion, and women accompanied by their partner to the abortion clinic coped less well immediately after the abortion than women unaccompanied by their partner.

Abortion, Induced↗
PubMed1984

Alteration of antibody-mediated responses of suckling mice to T-cell-dependent and independent antigens by maternal marginal zinc deficiency: restoration of responsivity by nutritional repletion.

To further characterize the effects of marginal zinc deficiency on the development of the immune system of the suckling A/J mouse, dams were fed marginal (1.6 micrograms Zn/g), intake restricted (30 micrograms Zn/g) or adequate (30 micrograms Zn/g) levels of dietary zinc days 5-17 postpartum. Marginal levels of zinc had little effect on the body weight of dams; however, their pups were only 71-75% the weight of control pups. In response to two T-cell independent (TI) antigens pups of low zinc dams could produce only 49 and 44% as many antibody-producing cells per spleen as control pups. Pups of restricted-fed dams produced about 60% as many cells as controls for each TI antigen. The avidities of the plaques produced by pups of restricted and control dams in response to TI antigens were nearly the same but were 5.5 times higher than the relative avidities of the antibodies produced by pups of low zinc dams. The responses of the deficient pups to sheep red blood cells (SRBC), a T-dependent (TD) antigen, were 25-30% of response of control and 56-75% of that of restricted pups depending on whether direct (IgM) or indirect (IgG) plaques were enumerated. The data demonstrate that marginal deficiencies in zinc during lactation greatly reduce the ability of suckling pups to mount antibody-mediated responses and suggest that the kinds of lymphocyte subsets found in deficient pups are altered. However, antibody-mediated response capacity was normal in the deficient pups following a short period of zinc supplementation.

Animal Population Groups↗