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  • 1
    Electronic Resource
    Electronic Resource
    Histological changes in the normal rat brain after gamma irradiation (1996)
    Springer
    Acta neurochirurgica 138 (1996), S. 451-459 
    Details
    ISSN: 0942-0940
    Keywords: Radiosurgery ; Gamma Knife ; radiation necrosis ; rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Radiation-induced changes in the parietal cortex of Wistar rats were observed at various time points after gamma surgery. Maximum dosages of 50, 75, and 120 Gy were given at the iso-center of the radiation using a 4-mm collimator. Conventional histochemical and immunocytochemical analyses, and computer-assisted videomicroscopy were utilized to examine perfusion-fixed brain tissue. Irradiation at a dosage of 50 Gy elicited morphological changes of astrocytes in the parietal cortex at 3 months. Vasodilatation became obvious at 12 months; fibrin deposition was observed in the dilated capillary wall. Neither leakage of Evans Blue from the vasculature into the tissue nor necrosis was observed across the 12 month observation period. Irradiation at a dosage of 75 Gy resulted in morphological changes of astrocytes within 1 month. Dilatation of vessels and capillary thickening were observed at 3 months. Evans Blue leakage and necrosis were observed at 4 months after 75 Gy irradiation. At this time, the walls of arterioles became thickened by subintimal accumulation of fibrin and hyaline substance; this sometimes resulted in occlusion of the lumen. Significant hemispheric swelling was observed at 4 months. Irradiation at a dosage of 120 Gy elicited changes in astrocytic morphology within 3 days. Evans Blue leakage into the tissue was observed by 3 weeks. Vasodilatation became marked at this time point and rarefaction was observed in the irradiated cortex. Necrosis was observed at 4 weeks, however, no significant swelling was observed. Taken together, these findings demonstrate time-dependent and dosage-dependent changes in normal cerebral tissue after Gamma Knife irradiation. These results provide a basis for gauging the impact of gamma surgery in regions of eloquent tissue. An enhanced understanding of the cellular responses to radiosurgery will contribute to developing and evaluating future applications for gamma surgery.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01420308
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  • 2
    Electronic Resource
    Electronic Resource
    Enhanced magnetic resonance imaging of the rat brain using a stereotaetic device with a small head coil: Technical note (1995)
    Springer
    Acta neurochirurgica 133 (1995), S. 87-92 
    Details
    ISSN: 0942-0940
    Keywords: MRI ; rat, brain ; stereotactic atlas ; Gamma Knife
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A stereotactic device (SDM) was developed for performing consistent magnetic resonance imaging (MRI) of the rat brain. The SDM was developed by adapting a radiofrequency transmit/receive head coil of 4.4 cm inner diameter (quadrature birdcage head coil), and utilizing partial acrylic construction for the positioning elements. The small head coil provides improved resolution and accuracy of the image, while the stereotactic holder permits repeatable and accurate imaging of identified brain structures. This system provides several advantages over existing experimental MRI devices. The SDM ensures that the head is always placed in the center of the coil in a uniform fashion. Standardized positioning of the skull optimizes image quality and provides a consistent orientation of the brain. In addition, a widely-utilized coordinate system described by Paxinos and Watson can be employed to assist in the identification of structures and to facilitate surgical planning. The SDM is compatible with a recently-developed stereotactic device for radiosurgery with the Gamma Knife, thus permitting the planning and performance of experimental radiosurgery using the same coordinate system. The SDM also provides the ability to perform MRI and radiosurgery at different times, thus avoiding the need for prolonged anesthesia during an experimental study. Finally, the SDM allows repeated MRI of the same, identifiable positions in the brain during longitudinal experimental studies. The utility of this device is demonstrated here by examining the time course of cerebral damage that evolved within a radiosurgical focus after gamma irradiation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01404955
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  • 3
    Electronic Resource
    Electronic Resource
    A stereotactic device for experimental Gamma Knife radiosurgery in rats (1993)
    Springer
    Acta neurochirurgica 125 (1993), S. 156-160 
    Details
    ISSN: 0942-0940
    Keywords: Gamma Knife ; radiosurgery ; rat ; stereotaxis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A rat stereotactic device was designed for use in Gamma Knife radiosurgery. Experimental radiosurgical lesions were made in superficial and deep cerebral structures to verify the accuracy of the coordinate system, which is based on a standard rat stereotactic atlas. Calculated dosages were shown to be accurate utilizing thermoluminescence dosimetry. Two additional features of the device permit the surgical positioning and placement of electrodes, and postmortem slicing of the brain according to the same coordinate system. This new apparatus allows precise and repeatable gamma irradiation of the rat brain without the need for expensive and time-consuming imaging techniques. Studies of this type will provide a rapid means for examining the effects of radiosurgery on the central nervous system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01401844
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  • 4
    Electronic Resource
    Electronic Resource
    Occlusion of the anterior cerebral artery after gamma knife irradiation in a rat (1996)
    Springer
    Acta neurochirurgica 138 (1996), S. 983-991 
    Details
    ISSN: 0942-0940
    Keywords: Gamma Knife ; radiosurgery ; artery ; arteriosclerosis ; vasculitis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The anterior cerebral artery of rats was irradiated at the level of the circle of Willis by Gamma Knife with a maximum dose of 25, 50, or 100 Gy. Occlusion of the anterior cerebral artery was observed in one rat which was followed for 20 months after irradiation of 100 Gy. Cerebral infarction was found at the midline-frontal region and the cingulate gyrus. Arterial wall thickening with fibrosis, splitting of the internal elastic membrane, luminal organized thrombus, and migration of smooth muscle cells into the thrombus were observed. In the anterior cerebral artery, thrombus formation seemed to occur after the endothelial injury and this may play a prominent role for occlusion. In small arteries, various changes were observed in the irradiated tissue. These included fibrosis and thrombus, thickened smooth muscle layer, lymphocytic infiltration, and thickening of vessel wall with fibrosis and fibrinous thrombosis with leakage of fibrin into the surrounding tissue after different doses of radiation and at different observation times. These changes were comparable to the ordinary vascular response to injury including healing vasculitis and arteriosclerosis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01411289
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  • 5
    Electronic Resource
    Electronic Resource
    Accuracy of an experimental stereotactic system for MRI-based Gamma Knife irradiation in the rat (1996)
    Springer
    Acta neurochirurgica 138 (1996), S. 1103-1108 
    Details
    ISSN: 0942-0940
    Keywords: Gamma Knife ; MRI ; Stereotactic atlas ; rat ; stereotactic device
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Stereotactic devices for experimental Gamma Knife irradiation and magnetic resonance imaging (MRI) have recently been developed for experimental studies using rats [6, 7]. The present study examined the accuracy of these devices using the following two approaches. In the first approach, Gamma Knife irradiation was performed using the stereotactic device with targets based on a standard stereotactic atlas. Gadolinium-enhanced T1-weighted magnetic resonance imaging was performed using the MRI stereotactic device. Animals were then sacrificed after Evans blue injection, and the rat brain was sliced using an attachment to the stereotactic device. The center coordinates of the gadolinium-enhanced area from the MRI and Evans blue-stained area from the tissue sections were obtained using a computer-assisted image analysis system. These coordinates were compared with the target coordinates planned from the stereotactic atlas. In the second approach, a thermoluminescence dosimeter was implanted in the rat brain. Stereotactic MRI was performed using the stereotactic MRI device, and the coordinates of the implant were obtained. Gamma Knife irradiation was then performed at this target using the stereotactic device. The absorbed dose was measured and compared with the planning dose. These experiments demonstrated a spatial error of 0.6 mm (standard error ± 0.07) between Gamma Knife irradiation based on a comparison of the atlas coordinates and the lesion, and a spatial error of 1.0 mm (standard error ± 0.13) based on a comparison of the stereotactic MR images and the lesion. Gamma Knife irradiation based on MR images using the stereotactic device demonstrated a maximum error of 10% in absorbed dose at the target center. Together, the stereotactic devices for Gamma Knife irradiation and magnetic resonance imaging provide useful tools for Gamma Knife research in an animal model.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01412315
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  • 6
    Electronic Resource
    Electronic Resource
    Histogenetic potential of rat hind-limb interdigital tissues prior to and during the onset of programmed cell death (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 236 (1993), S. 568-572 
    Details
    ISSN: 0003-276X
    Keywords: Interdigital mesoderm ; Programmed cell death ; Chondrogenesis ; Rat embryo ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The histogenetic potential of interdigital tissues isolated from the autopod of rat embryonic hind-limbs between 14.5 and 16.5 days was investigated. A wedge of tissue containing ectoderm and mesoderm was excised from between the developing digits and grafted beneath the kidney capsule of adult rats for two weeks. We have previously demonstrated that the renal capsule is an excellent site for permitting limb tissues to proliferate and differentiate (Chan et al.: J. Exp. Zool., 260:74-83, 1991). At 14.5 days, when cell death (revealed with neutral red stains) within the interdigital zone was limited to the apical ectodermal ridge (AER), the interdigital mesoderm was capable of developing into bone, cartilage, and loose connective tissue in the kidney. It was estimated that the skeletal elements occupied approximately 38% of the overall area of the grafts. In addition, the ectoderm was able to produce keratinized epithelium, hair follicles, and sebaceous glands. In 15.5 day autopod, necrosis was present both in the AER and the mesoderm between the AER and marginal sinus. Interdigital mesoderm obtained from this stage of development formed cartilage but not as extensively as that derived from 14.5 day autopod (4% as compared with 38%). Necrotic cells were present in all of the interdigital zones at 16.5 days. Ten explants were introduced into the kidney at this stage, but only 4 grafts were recovered after 2 weeks. In all cases, the explants did not produce cartilage. Only a small amount of keratinized epithelium and loose connective tissue was found. In summary the interdigital mesoderm has the potential to develop bone, cartilage, and loose connective tissue, but this ability is progressively lost during morphogenesis. © 1993 Wiley-Liss, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1092360317
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  • 7
    Electronic Resource
    Electronic Resource
    Migration of myogenic cells from the somites to the fore-limb buds of developing mouse embryos (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Developmental Dynamics 203 (1995), S. 324-336 
    Details
    ISSN: 1058-8388
    Keywords: Somites ; Limb bud ; Myogenic cells ; Transgenic embryos ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: In this study, we have isolated newly formed somites from the caudal regions of 8.5 day mouse embryos and transplanted them orthotopically into correspondingly staged hosts at the level of the prospective limb-forming region. The experimental embryos were then cultured intact for 32-36 hr. The donor somites used were pre-labelled with DiI, a fluorescent lipophilic dye, or were obtained from transgenic embryos that carried a 1 kb 5′ regulatory sequence of the desmin gene linked to the gene encoding Escherichia coli β-galactosidase. The transgene is specifically expressed in skeletal muscles (Li et al. [1993] Development 117:947-959). The aim of these experiments was to show definitively that the musculature of the mammalian limb is derived from the somites. The results demonstrated that DiI-labelled cells from the implanted somites were able to invade the proximal region of the fore-limb bud during the course of development. The use of transgenic somites as grafts confirmed that some of the somitic cells found in the limbs were myogenic cells. To determine whether the displacement of somitic cells is an active or passive process, somatopleure obtained from the prospective limb-forming regions of day 8.5 day embryos was implanted into 8.5 day hosts. We did not detect the presence of DiI-labelled somatopleural cells in the fore-limb after 32-36 hr of culture. This suggests that somitic cells reached the limb bud via active locaomotion rather than as a result of being passively dragged there, as the limb elongates during development. In addition, we injected latex beads into the somites, as probes, to determine whether extracellular matrix-driven translocation plays a role in driving the somitic cells to the limb bud. In a majority of the specimens examined, we could not detect the presence of these beads in the limb bud. However, in the trunk of these embryos, the beads were found dispersed throughout the ventral neural crest pathway.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aja.1002030305
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  • 8
    Electronic Resource
    Electronic Resource
    Histochemical identification of primordial germ cells in diandric and digynic triploid mouse embryos (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 25 (1990), S. 364-368 
    Details
    ISSN: 1040-452X
    Keywords: Ploidy ; Alkaline phosphatase ; LT/Sv strain mice ; Nuclear micromanipulation ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Diandric and digynic triploid mouse embryos were isolated in the morning on day 10 of gestation. The embryos were separated from their extraembryonic membranes, and the latter were analysed cytogenetically by G-banding to establish the ploidy and sex chromosome constitution of these embryos. The diandric triploid embryos were produced by the technique of nuclear micromanipulation. Females were mated with male mice with a morphologically distinguishable “marker” chromosome to confirm the diandric status of these embryos. Digynic triploid and normal diploid embryos were isolated form LT/Sv strain females. These females spontaneously ovulate both primary and secondary oocytes, which are fertilisable and give rise to digynic triploid and normal diploid embryos, respectively. All the embryos were serially sectioned and processed in order to dmonstrate the presence of alkaline phosphatase enzyme activity. This histochemical technique allowed primordial germ cells to be readily recognised, due to their characteristic location, cellula morphology, and staining appearance. Primordial germ cells were found in all the embryos studied, being located within the visceral yolk sac, at the base of the allantois, and/or in association with the wall or mesentery of the hindgut. The total number of germ cells present was established in nine diandric triploids and in five digynic triploids. The findings presented here represent the first demonstration that primordial germ cells can differentiate in either diandric or digynic triploid mammalian embryos.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1080250409
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  • 9
    Electronic Resource
    Electronic Resource
    Interactions of dimethyl sulfoxide and granulocyte-macrophage colony-stimulating factors on the growth and maturation of HL-60 cells (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 132 (1987), S. 246-254 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We have studied the interactions of dimethyl sulfoxide (DMSO), Giant Cell Tumor (GCT) cell-conditioned medium (GCT CM), and highly purified granulocyte-macrophage colony-stimulating factors (GM-CSF) on the growth and maturation of a highly passaged population of HL-60 cells. DMSO produced dose-dependent inhibition of HL-60 growth in liquid and semisolid media. Growth was partially to completely restored by the addition of GCT CM to cultures. Experiments in which cell volume, cell cycle kinetics, tritiated thymidine (3HTdr) incorporation, cell number, and nitroblue tetrazolium (NBT) reduction were compared during culture indicated that DMSO inhibited the spontaneous increase in cell volume and flow of cells through the cell cycle which occurred in the first day of culture, the increase in 3HTdr incorporation which was detectable by day 2; and the increment in cell counts which occurred by day 3. These effects were opposed by GCT CM. In contrast, the DMSO-induced increase in NBT reduction which occurred by day 6 was not influenced by GCT CM. The major principle opposing DMSO was GM-CSF, since (1) highly purified GM-CSF from GCT cells and recombinant GM-CSF from COS cells transfected with the Mo cell GM-CSF gene overcame greater than 50% of DMSO inhibition; and (2) conditioned media from cells not producing CSF, G-CSF from GCT cells, and recombinant G-CSF from Escherichia coli transfected with the G-CSF gene from 5,637 cells were inactive. DMSO had little or no effect on the elaboration of autostimulatory activity by HL-60 cells. DMSO is a useful agent for inhibiting the spontaneous growth of HL-60 cells and restoring their dependence on GM-CSF, a property which may be mediated through the effects of DMSO on cell cycle kinetics and/or maturation.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041320208
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  • 10
    Electronic Resource
    Electronic Resource
    Dibutyryl cyclic adenosine monophosphate differentially regulates cell proliferation in low and high alkaline phosphatase SaOS-2 human osteosarcoma cells: Evidence for mediation by the insulin-like growth factor-II system (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 156 (1993), S. 462-468 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In the present study, we have sought to determine whether a given signal transduction pathway can have diverse effects on subpopulations of cells of a lineage depending upon the stage of differentiation. To test this hypothesis, we selected the cyclic adenosine monophosphate (cAMP) signal transduction pathway because of its recognized importance in mediating the actions of many hormones, e.g., parathyroid hormone which acts on the bone-forming cells, the osteoblasts. Subpopulations of human osteosarcoma SaOS-2 cells with low (LSaOS) and high (HSaOS) alkaline phosphatase (ALP) content were chosen as model systems for preosteoblasts (pre-OB) and osteoblasts (OB), respectively. Dibutyryl cyclic AMP (DBcAMP) treatment of serum free cultures produced a differential effect on the proliferation of LSaOS cells (40 ± 5% of control at 1 mM DBcAMP, P 〈 0.001) compared with HSaOS cells (no statistically significant effect). The finding supports the hypothesis. Next, we sought evidence for mediation, at least in part, by the insulin-like growth factor (IGF)-II regulatory system. We report that the basal expression of IGF-II, IGF binding protein (IGFBP)-3, and IGFBP-4 was higher in LSaOS cells than in HSaOS cells with the opposite true for type I IGF receptor. DBcAMP treatment of LSaOS cells decreased IGF-II and IGFBP-3 but increased IGFBP-4 and type I IGF receptor; no effect was observed for the type II IGF receptors. DBcAMP treatment of HSaOS cells had no detectable effect on IGF-II; IGFBP-3, or type I and type II IGF receptor expression; only IGFBP-4 expression increased with DBcAMP. These observations suggest that the differential regulation of cell proliferation by the cAMP signal transduction pathway may be mediated, at least in part, by the IGF-II regulatory system. © 1993 Wiley-Liss, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041560305
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