Biomedical subjects
Publications and source records attributed to J Althoff.
The effect of cyclophosphamide and N-nitrosomethylurea(NMU) was intensified by combining these alkylizing substances. The effects of the combination (variable malformations of the teeth) appear after a shorter latency period.
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The postnatal development and differentiation of the tracheal epithelium in Syrian golden hamsters was examined by SEM. Surface structures indicate a proliferative growth for the first 10 days after delivery, but differentiation into a mature respiratory epithelium is still incomplete on the 30th day post partum. Cells with microvilli (less differentiated cells, mucus cell precursors and mucus-producing cells) outnumbered ciliated cells up to the 20th day. The topographical distribution of ciliated cells was different at various stages of development in the pars membranacea, pars intercartilaginea and pars cartilaginea. Depending on the time of their development and differentiation, the different cell types in the respiratory epithelium provide useful information on induced alterations because of the high degree of specialisation on their surface.
Differentiation of the Syrian golden hamster respiratory epithelium (trachea) was followed sequentially for 28 days in vitro after explantation of fetal tissue. It was shown that the epithelium stays alive, develops and differentiates at time periods and with patterns similar to those observed in vivo. In general, the surface structure and topographical distribution of cell types are identical to those seen in vivo. Differentiation into mucogenic cells appeared to be enhanced to some extent towards the end of the observation period.
In an inhalation study, two groups of male Syrian golden hamsters were exposed to 9.8 and 44.8 mg BP/m3 air respectively for 16 weeks. No significant histological or pathological alterations were seen, and no tumours were found which could be related to BP exposure.
The effect of a single subcutaneous injection of different DEN doses was examined in adult Syrian hamsters observed for life. The minimal effective dose (threshold dose) for neoplastic response, reflected by induction of papillary polyps in the larynx and/or trachea, was 1.03 mg DEN/kg body weight. No tumors were found which could be related to treatment in other segments of the respiratory epithelium nor in other tissues.
Different doses of benzo(a)pyrene, cigarette smoke condensate (CSC) and its nitromethane fraction (NMF), in wax pellets, were directly implanted into the lungs of Syrian golden hamsters. Pleomorphic sarcomas were induced in the B(a)P treated animals. Several epithelial proliferative lesions and a few bronchiogenic adenomas were induced in CSC and NMF treated hamsters. A species-specific effect has been observed in this investigation.
Surface epithelial cells from 55 biopsies including lichen planus, leukoplakia and squamous cell carcinoma were studied by scanning electron microscopy. The surface structures of the various oral lesions demonstrated morphological differences. After more information has been collected, the method of SEM may be of value for the recognition of pre- and early neoplastic lesions in the oral cavity.
Hamsters of three types designated as inbred cream (Epp/e/e), linebred white (EPP/cdcd/RB/A), and linebred albino (EPP/cdcde/e) were thoroughly examined histopathologically for spontaneous diseases. All hamsters were maintained simultaneously for life under identical standard laboratory conditions. Marked differences were found in longevity of the animals and in incidence, sites, patterns, and types of spontaneous diseases. In cream hamsters (CH), survival time was shorter than in white hamsters (WH) and albino hamsters (AH). More tumors and malignant lesions unrelated to survival were found in AH compared to CH and WH; also, the multiplicity of neoplasms were more pronounced in AH. The predominating tumor types differed in each line: Pancreatic islet cell neoplasms were most common in CH, adrenal gland tumors predominated in WH, and thyroid gland tumors in AH. Also, the relative incidence of spontaneous tumors varied among the lines. Some tumors seemed strain-specific and were not seen in other lines; malignant melanomas, for example, occurred only in CH and WH. Certain neoplasms, e.g., those of the thyroid and adrenal glands, were found more often in one sex than the other. The three hamster groups differed also in nonneoplastic diseases. Detailed histopathologic findings are presented and compared with data on the Syrian golden hamster, the ancestral line of these three groups.
Sprague-Dawley rats received intragastrically a single dose of 226Ra or 224Ra once weekly for 21 weeks. During this period the animals of both groups were thus exposed to comparable doses. After 12 weeks, a shortening of the maxillary incisors was observed, and this progressed during the course of the 55-week experiment. Radiologically, a loss of pulpal transparency and an apical irregular opacity in the maxillary incisors were demonstrable. Histologically, dysplastic changes of the maxillary incisors and multiple resorptions at the cemento-enamel junction of the molars were seen. The observed alterations were more pronounced in the 226Ra group than in the 224Ra treated group. The experimentally induced resorptions were comparable to those observed in patients who had incorporated 224Ra or 226Ra. Clinical, radiological, histological, gamma-spectrometrical, and autoradiographical findings, as well as dose-estimations, are described.
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The carcinogenic effects of low doses of 10 nitrosamines were determined in pregnant Syrian golden hamsters and their offspring. Compounds studied included dimethylnitrosamine, di-n-propylnitrosamine, di-n-butylnitrosamine, nitrosopiperidine, nitrosohexamethyleneimine, 2-dydroxypropyl-propyl-nitrosamine, 2-oxopropyl-propyl-nitrosamine, methylpropylnitrosamine, di(2-hydroxypropyl) nitrosamine, and 4-hydroxybutyl-butyl-nitrosamine. Tumor incidences of all organ systems were almost always higher and latencies shorter in the mothers than in the offspring. Exceptions occurred in the respiratory system in which several compounds induced a low incidence of tumors in the offspring but none in the mothers. Fetal susceptibility appeared greatest toward the end of gestation. For purposes of bioassay, transplacental exposure was less efficient than conventional adult treatment.
Alkaline phosphatase from tibia tendon of Meleagris gallopavo L. was highly purified. The enzyme activation by different ions was measured. Mg2+ showed a high activation with a broader spectrum of phosphomonoester hydrolization. The in vivo Mg2+ concentration was an optimum for in vitro activation.