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Biomedical subjects

G Wöber

Publications and source records attributed to G Wöber.

At least 19 recordsLinked to original sources
PubMed1978

Continuous cultivation in a chemostat of the phototrophic procaryote, Anacystis nidulans, under nitrogen-limiting conditions.

Anacystis nidulans was grown photoautotrophically in a chemostat in the presence of light, air and CO2 as the sole carbon source. Either the amount of the nitrogen source in the medium or light intensity were used as growth-limiting parameters. 1. Cells of high glycogen content obtained by pre-incubation under nitrogen starvation conditions maintained their glycogen content during continuous cultivation. Both growth rate and the amount of cell-mass and of glycogen depended on the nitrate content of the medium and the light intensity. The values for the growth rate, the maximal rates of glycogen synthesis and of cell mass formation were 0.1 h-1, 6 mg/l.h and 17 mg/l.h, respectively. 2. Cells without glycogen which had been transferred from an exponentially growing batch culture to chemostat conditions showed increasing rates of growth and of cell mass formation when the light intensity was increased. A determination of specific values resulted in 0.15 h-1 for growth rate and 23 mg/1.h for cell mass formation. 3. The chemostat apparatus is described in detail.

Cell Division↗
PubMed1978

alpha-Glucosidase, a membrane-bound enzyme of alpha-glucan metabolism in Bacillus amyloliquefaciens. Purification and partial characterization.

The organism Bacillus amyloliquefaciens is capable of producing alpha-amylase (1,4-alpha-D-glucan glucanohydrolase, EC 3.2.1.1) and isoamylase (glycogen 6-glucanohydrolase, EC 3.2.1.68) extracellurlarly and a membrane-bound, intracellular alpha-glucosidase (alpha-D-glucoside glucohydrolase, EC 3.2.1.20). The amounts of alpha-glucosidase in cells of B. amyloliquefaciens grown on amylaceous polysaccharides were significantly higher then in cells grown on non-carbohydrate carbon sources. alpha-Glucosidase was exclusively found associated with membranes from ruptured spheroplasts by subcellular fractionation and solubilization studies. Salt solutions and chelating agents alone did not dislodge alpha-glucosidase from membranes, but in combination with detergents were most effective in solubilizing active enzyme (0.1% sodium cholate (pH 8.0)/0.4 M sodium chloride). Purified alpha-glucosidase very rapidly hydrolized p-nitrophenyl alpha-D-glucopyranoside and sucrose. Maltose, maltotriose, isomaltose and isomaltotriose were hydrolized at slower rates, whereas beta-glucosides and polymeric alpha-glucans were not attacked. Other properties of the purified enzyme were as follows: Temperature optimum for catalysis = 39 +/- 1 degrees C; pH optimum = 6.8; molecular weight = 27,000 +/- 1000. alpha-Glucosidase is proposed to function in the endogenous metabolism of alpha-glucans provided extracellularly as carbon sources for growth of B. amyloliquefaciens.

Bacillus↗
PubMed1977

[The management of urinary and fecal incontinence due to a neurinoma of the cauda equina with an electrode implanted in the pelvic muscles (Caldwell) (author's transl)].

A woman, aged 49, had a complete sensory and motor deficit of the S2-5 segments with urinary and fecal incontinence due to a neurinoma of the cauda. A Caldwell electrode was implanted surgically into the muscles of the pelvic floor in April 1974. The patient was observed for 2 years thereafter and had an excellent result. The medical and technical problems of treating urinary and fecal incontinence due to a lower motor neuron lesion of S2-5 can be handled satisfactorily with an implanted electrode.

Cauda Equina↗
PubMed1977

[The value of imprint cytology in neurosurgical diagnosis (author's transl)].

Cytological smear techniques have been found valuable in obtaining a rapid histological diagnosis during neurosurgical biopsies, although their accuracy is questioned. This method is particularly appropriate in the case of small pieces of tissue which may be difficult to cut in the cryostat. A method developed to obtain multiple touch preparations was used in 332 consecutive neurosurgical biopsies; these were examined and compared with subsequent paraffin sections of the same biopsies. The correct diagnosis was obtained from the smears in 93.7% of the cases, while the diagnostic accuracy of paraffin sections was 98.2%. The imprints also allowed correct grading of gliomas. Most of the errors or inconclusive cytological diagnoses stemmed from failure to distinguish between primary and secondary anaplastic CNS tumours, between neurinomas and fibroplastic meningiomas, or between glial scar or normal brain tissue and isomorphic astrocytomas. The differentiation of these lesions is, however, often difficult even in paraffin sections. In accordance with the results of other authors it is suggested that the touch cytology is one of the most appropriate techniques available for rapid neurosurgical diagnosis.

Cytological Techniques↗
PubMed1977

Morphological changes in anaplastic gliomas treated with radiation and chemotherapy.

The effects of antineoplastic treatment on gliomas are related to tumour cell cycle and proliferation kinetics, glioma tissue architecture, and the surrounding environment. Morphological changes induced by radiation and chemotherapy are characterized by cell necrosis and severe alterations in cell and nuclear morphology caused by changes in the cell kinetic parameters which, however, may also occur spontaneously in untreated anaplastic gliomas. Comparative studies of cytological imprints and routine histological preparations of biopsy and autopsy specimens were performed in four groups of anaplastic astrocytomas and glioblastomas (78 cases) with postsurgical irradiation, combination chemotherapy, and CCNU treatment, and without specific postsurgical treatment (control group). Following radiation and chemotherapy, in addition to increased necrosis and vascular response, a variety of characteristic but nonspecific changes were observed in cell and nuclear morphology with prominent formation of multinucleated giant and monstrous cells, irregular and hyperchromatic nuclei, and severe cytoplasmic degeneration indicating both inhibition of cell division and cell damage. Statistically significant findings were a posttreatment increase in the number of multinucleated giant and monstrous cells and a decrease in the number of mitoses. These changes were more pronounced after chemotherapy than after radiation, while no significant dissimilarities were found between combination chemotherapy and CCNU. The implications of these changes on the mechanisms of antitumour treatment in anaplastic gliomas are discussed.

Brain Neoplasms↗
PubMed1976

Accumulation, mobilization and turn-over of glycogen in the blue-green bacterium Anacystis nidulans.

1. Accumulation of glycogen up to a constant amount per cell was observed during the postexponential phase of growth, in the presence of an excess of a utilizable carbon source. Cell multiplication was reproducibly controlled by growth of the organism in a nitrogen-limiting medium under photoautotrophic conditions (presence of light, air plus CO2). 2. Temporary starvation, i.e. by removal of light or by the addition to an illuminated culture of DCMU, 3-(3',4'-dichlorophenyl)-1,1'-dimethylurea, a specific inhibitor of photosystem II, lead to a mobilization of glycogen in the cell. Furthermore, Anacystis nidulans, having accumulated glycogen by virtue of preculture under nitrogen-limiting conditions, will resume cell division when the culture medium is complemented with a nitrogen source. The ability of the organism to use glycogen as an endogenous carbon source for growth was observed by addition of a nitrogen source to nitrogen-starving cells and simultaneous removal of CO2. 3. During the period of constant amount of glycogen per cell the reserve polysaccharide was subject to turnover as demonstrated with a pulse chase-labelling technique. The demonstration of a turnover--for the first time with a bacterial species--indicated a strict balance in the relative rate of synthesis and degradation.

Cell Division↗
PubMed1976

[Intramedullary oligodendroglioma with meningocerebral dissemination (author's transl)].

A 28 year old woman suffered from lumbar radicular signs and sensory deficit for three years before death. A progressive illness with increased intracranial pressure, cerebellar signs, and multiple cranial nerve palsies appeared one year after the onset of symptoms, but craniotomy of the posterior fossa was negative. After development of spastic paraparesis, an intramedullary oligodendroglioma of the lower thoracic cord was partly removed. Death occurred two months later from raised intracranial pressure. At autopsy a diffuse oligodendroglioma was found involving the periventricular regions of the brain, the entire subarachnoid space, the cerebral parenchyma, and the whole length of the thoracic cord. There was a small lumbar syrinx. It is suggested in this case that the dorsal intramedullary oligodendroglioma was the source from which tumour spread diffusely through the cerebrospinal fluid pathways and secondarily invaded the cerebrum. The diagnostic difficulties of diffuse meningeal gliomatosis are discussed.

Adult↗
PubMed1975

Variation in average unit chain length of glycogen in relation to developmental stage in Blastocladiella emersonii.

Synchronous, single generations of Blastocladiella emersonii were grown along either the ordinary colorless or resistant sporangial plant pathways. Samples of cells were withdrawn at different developmental stages and glycogen was extracted, purified, debranched by isoamylase treatment, and its component unit chains separated by gel permeation chromatography. The elution profiles showed the distribution of unit chains. Average unit chain length was determined for plants at different developmental stages and shown to vary between 9 and 16. Some of these variations were correlated with other developmental events in the fungus.

Amylases↗
PubMed1975

Comparative biochemistry of alpha-glucan-utilization in Pseudomonas amyloderamosa and Pseudomonas saccharophila: physiological significance of variations in the pathway.

Growth patterns on and utilization of various alpha-glucans were investigated in Pseudomonas amyloderamosa and P. saccharophila. Maltose, maltodextrins (average chain length 7 glycosyl units) and glycogen supported excellent growth of both organisms and were extensively metabolized, although glycogen utilization in P. saccharophila was preceded by a prolonged lag phase. P. amyloderamosa produced limited growth on amylopectin and the carbohydrate was only partly degraded. It seemed likely that many of the unit chains liberated from amylopectin had a length exceeding the substrate range accepted by the maltodextrin permease (transport) system. A correlation was established between the pH of the medium and the utilization of glycogen and amylopectin for growth in P. amyloderamosa. The carbohydrates were at least partly utilizable at pH 6.0, whereas they could not support any growth at pH 6.5. Most likely, the lack of growth at the higher pH reflected the low activity of isolamylase at this pH. The enzyme patterns of maltodextrin catabolism in the two bacteria were established. Intracellularly, maltodextrin phosphorylase and 4-alpha-glucanotransferase occurred in both. Degradation of extracellular alpha-glucans was mediated by a mainly intracellular isoamylase in P. amyloderamosa, whereas P. saccharophila possessed an extracellular alpha-amylase and a firmly cell-bound pullulanase.

Amylases↗