Publications by authors named "Dorn A"

The immunolocalization of thiol: protein disulfide oxidoreductase (TPO) in CNS of Wistar rats and homozygous Brattleboro rats was investigated by use of monospecific antiserum and Sternberger's unlabelled immunoenzyme technique. It was revealed that TPO is present in hypothalamic neurons belonging to nucleus supraopticus and paraventricularis. The number of immunopositive nerve cells was reduced in Brattleboro rats as compared to Wistar rats.

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The cellular localization and regional distribution of cathepsin B within rat CNS was revealed by immunohistochemistry using a monospecific antiserum. Cathepsin B protein was found to be widely but unevenly distributed throughout rat brain. Neurons were always cathepsin B immunoreactive.

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The occurrence of beta-lipotropin (beta-LTH) immunoreactive material was investigated in the inner ear of newborn and juvenile guinea pigs by means of Sternberger's PAP technique. Unlike met5-enkephalin and endorphin, beta-LTH could not be found in the organ of Corti but was identified in the spiral ganglion and the neuroepithelium of the crista ampullaris.

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We have recently shown that the aggregation factor (AF) from the sponge Geodia cydonium stimulates DNA synthesis in quiescent, dissociated cells from the same organism; this event was correlated with the release of the two second messengers: inositol trisphosphate and diacylglycerol. Here we describe that after binding of the AF to the plasma membrane-bound aggregation receptor, a rapid and drastic increase in the incorporation of 32Pi into a series of proteins in the pore complex-lamina fraction occurs. Addition of the tumor promoter, 12-O-tetradecanoylphorbol-13-acetate, to quiescent cells resulted in a similar stimulation of phosphorylation of nuclear proteins.

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NF-Y is a sequence-specific DNA-binding protein that interacts with the conserved Y motif of the major histocompatibility complex class II gene, E alpha. Since it is actually a CCAAT box-binding protein, NF-Y also attaches to other promoters bearing CCAAT sequences; yet, it is neither of the previously described transcription factors, CBP or CTF/NF-1. In this report, we document the cell-type distribution and various biochemical properties of NF-Y.

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NF-Y is a sequence-specific DNA-binding protein that recognizes the Y box, a promoter element common to all major histocompatibility complex class II genes. Since the 14-base Y element harbors a CCAAT box in reverse, we were prompted to ask whether NF-Y is actually a CCAAT box-binding protein and whether it is related to the previously described CCAAT-binding factors CBP and CTF/NF-I. Data from gel retardation, methylation interference, saturation mutagenesis, and cross-competition experiments establish definitively that NF-Y is an entirely distinct CCAAT box-binding entity.

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A conserved sequence motif exists at the 5' end of all major histocompatibility complex class II genes. This motif consists of the 14-base X and Y boxes separated by a short stretch of variable sequence. In this report, we provide evidence that the X and Y boxes play an important role in controlling transcription of the murine class II gene E kappa alpha.

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Soft tissue surgery of the head and neck.

Tijdschr Diergeneeskd

April 1987

A variety of surgical techniques and procedures have been described for diseases of soft tissues of the oral cavity. Mandibulectomy and maxillectomy have been described for the management of oral neoplasia. These procedures involve removal of parts of the mandible and maxilla in the affected regions of the mouth.

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Urinary tract trauma.

Tijdschr Diergeneeskd

April 1987

Trauma to the canine urinary tract is a common occurrence secondary to motor vehicle accidents. Radiology is an important diagnostic technique for determining the extent of traumatic injuries. The anatomic location of the urinary system in close association with the ribs, pelvis, epaxial muscles and spine may be an advantage because of the protection offered by these structures and a disadvantage because of increased injury when these structures are damaged.

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The medulla region of sponges (= mesohyl) is only rarely dispersed with cells (approximately 25% of the total tissue volume). In vivo studies with a series of anti-cytoskeletal drugs revealed that taxol caused a significant contraction of intact specimens. Therefore, we investigated the possibility that microtubules are one component of the dynamic extracellular network in sponges, especially in the mesohyl.

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Head segments and brains were extirpated from embryos of the tobacco hornworm, Manduca sexta, extracted and the resulting extracts assayed for prothoracicotropic hormone (PTTH) activity on prothoracic glands from day 3 fifth instar larvae and day 0 pupae. Dose-response curves were generated and indicated the presence of PTTH activity in embryonic brains and head segments, suggesting a role(s) for this neurohormone during embryogenesis. Maximal PTTH activity was found in brains from embryos 117 h post-oviposition, just prior to hatching, but activity was also noted in head segments as early as 24 h post-oviposition.

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L-Ornithine decarboxylase, the rate limiting enzyme of polyamine biosynthesis and a marker enzyme of tissue proliferation and maturation, was localized immunocytochemically in the developing rat central nervous system. It can be noted that the distribution of the enzyme protein underlies temporal alterations. Conclusions are drawn from the localization of the enzyme and possible functional roles played by ornithine decarboxylase in discrete brain areas.

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The degradation of insulin and glucagon was investigated in rat brain, kidney, and liver during postnatal ontogenesis. It was found that a maximal activity around 13 d is unique for CNS and differs remarkably from time-course in liver and kidney. It is concluded that this result supports the hypothesis of a growth promoting role of insulin in developing rat brain.

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An antiserum against rat liver cathepsin D, which was previously found to cross-react with human brain cathepsin(s) D, was used to immunolocalize the enzyme in developing CNS man. Cathepsin D protein was found in neurons as well as in glial cells. The aerliest occurrence of cathepsin D was observed in neuroblasts at the 12th gestational week.

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Monospecific antisera against cathepsins B, D, and H were used to immunolocalize these proteinases in neural structures of rat brain. Cathepsins B and D were found to be largely co-localized in nerve cells. Cathepsin H could not be identified by use of immunocytochemistry.

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By means of immunohistochemical techniques we have investigated the presence of dipeptidyl aminopeptidase IV immunoreactivity in brain material derived from human fetuses, newborns and aged persons. It was revealed that the enzyme protein is abundantly present in the immature human CNS. On the contrary the adult human brain contains much less dipeptidyl aminopeptidase immunoreactivity.

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The secondary metabolite avarol, a potent cytostatic and antibacterial sesquiterpenoid hydroquinone, is present in large amounts only in the sponge Dysidea avara (2.7 g avarol/1 kg of fresh material). The present study was designed to determine the storage site of this compound within the organism.

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Monoclonal antibodies (McAbs) were raised against the aggregation factor (AF) from the marine sponge Geodia cydonium. Two clones were identified that secrete McAbs against the cell binding protein of the AF complex. Fab fragments of McAbs: 5D2-D11 completely abolished the activity of the AF to form secondary aggregates from single cells.

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We determined the extracellular electrical current pattern around Drosophila follicles at different developmental stages (7-14) with a vibrating probe. At most stages a characteristic pattern can be recognized: current leaves near the oocyte end of the follicle and enters at the nurse cells. Only at late vitellogenic stages was an inward-directed current located at the posterior pole of many follicles.

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The aspartic endopeptidase cathepsin D was demonstrated in post mortem human brain by means of the peroxidase-antiperoxidase technique. The enzyme protein was found to be present in multiple neurons as well as in some glial cells. In embryonic nervous tissue cathepsin D was detected as early as at the 12th gestational week.

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