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D Ziegler

Publications and source records attributed to D Ziegler.

107 records · Page 6Linked to original sources
PubMed1977

An analysis of transport, exchange, and binding of sodium and potassium in isolated amphibian follicles and denuded oocytes.

The uptake and efflux of 22Na and 42K were studied in fully grown, prophase-arrested Rana pipiens follicles and denuded oocytes. Follicles and denuded oocytes contained large stores of both cations, although only 15--30% of the total Na+ and 1--2% of the total K+ pools exchanged within the 12-h period studied. 22Na uptake and efflux in follicles exhibited two-step kinetics with a smaller rapidly exchanging fraction (12--15%, t0-5 approximately 15 min), and a larger slow fraction (t0-5 approximately 0-5 day). Denuded oocytes displayed a single kinetic fraction with a rate constant similar to the slow fraction of follicles, suggesting that the fast fraction was associated with the follicular epithelium. Both follicles and denuded oocytes exhibited fast and slow 42K uptake kinetic fractions, although the follicular fast fraction was considerably larger. Conversely, whereas follicular 42K efflux also proceeded with two-step kinetics, 42K efflux from denuded oocytes appeared as a single slow fraction. Thus, a large portion of the fast K+ fraction taken up by the follicles is attributable to the somatic cells of the follicular envelopes. Na+ and K+ activities were measured in the cytoplasm of the in situ (follicular) oocyte using cation-selective microelectrodes. After correcting for Na+ and K+ associated with the follicular envelopes, only about 6% of the total ooplasmic Na+ and less than 1% of the K+ could be accounted for as bound or sequestered.

Animals↗
PubMed1977

Selective isolation of Vibrio cholerae neuraminidase using an immobilized 4-(nitrophenyl)oxamic acid.

N-(4-Nitrophenyl)oxamic acid[1] (1) was coupled with Sepharose 4B containing 1,6-diaminohexane as spacer group. This material was used as a specific adsorbent in the purification of Vibrio cholerae neuraminidase. The enzyme was completely retarded and separated from the bulk of the protein when washed with 50mM sodium acetate buffer, pH 5.0. A stepwise increase of sodium chloride concentration from 1.0 to 2.0M was found to be necessary for a sharp elution of neuraminidase activity. The purification was tenfold, and a recovery of more than 90% was obtained. Neuraminidase is only weakly retarded on a column of 1,6-diaminohexane coupled with Sepharose 4B and is not adsorbed by Sepharose 4B.

Chromatography, Affinity↗
PubMed1977

Inhibition studies on Vibrio cholerae neuraminidase.

A series of viral neuraminidase inhibitors showing no structural analogy to neuraminic acids have been tested to find whether they are effective inhibitors of V. cholerae neuraminidase, too. Here we report the results obtained with the N-phenyloxamic acid derivatives 2 to 6 (R-NH-CO-COOR'; R = -C6H5NO2, -C6H5OH, -C6H5NH2; R' = -H, -C2H5; see Table 1) and with simple aromatic compounds structurally related to R, i.e. 4-nitroaniline (7), N-acetyl-4-nitroaniline (8), 4-nitrophenol (9), 2,4-dinitrophenol (10), and 4-aminophenol (11) (see Table 2). The inhibitory effects of 2 to 11 were studied according to the method of Dixon[19] in 0.1m sodium acetate buffer, pH 5.5, 2mM CaCl2, at 37 degrees C using the benzyl-alpha-ketoside of N-acetyl-D-neuraminic acid (1) as a substrate. The compounds 2 to 11 are shown to be competitive inhibitors of the enzymatic hydrolysis of the alpha-ketoside 1. The competitive inhibition kinetics are supported by the method of Lineweaver and Burk[20]. The inhibition constants (Ki) are found to be in the range of 0.03 to 5.7 mM. The simple aromatic compounds 7 to 11 show higher inhibitory activities than the phenyloxamic acid derivatives 2 to 6. In addition, significant differences in the Ki values were observed within the two series of inhibitors, whereby those containing a nitro group were most effective.

Aniline Compounds↗
PubMed1976

Control of chromosome behavior in amphibian oocytes. II. The effect of inhibitors of RNA and protein synthesis on the induction of chromosome condensation in transplanted brain nuclei by oocyte cytoplasm.

We studied the effects of actinomycin D, alpha-amanitin, puromycin, and cycloheximide on the cytoplasmic activity of maturing Rana pipiens oocytes that induces chromosome condensation in transplanted brain nuclei. Treatment of oocytes with each inhibitor suppressed the chromosome condensation induced by metaphase oocytes to varying degrees depending upon the dose of inhibitor, despite the fact that untreated metaphase I oocytes already possessed chromosome condensation activity (CCA). Treatment of brain nuclei before injection completely suppressed condensation at all doses used. Chromosome condensation induced by metaphase II oocyte cytoplasm, however, was insensitive to all the inhibitors, even when the brain nuclei were pretreated. Oocytes treated with alpha-amanitin throughout maturation induced chromosome condensation when tested at metaphase II. Removal of the oocyte chromosomes after the germinal vesicle (GV) broke down did not prevent the development of CCA, whereas removal of the entire GV before initiation of maturation deprived oocytes of CCA. The results suggest that metaphase I oocyte cytoplasm stimulates synthesis of brain nuclear RNAs that are translated into proteins necessary for chromosome condensation, whereas metaphase II oocytes possess all the factors for chromosome condensation. In both cases, GV nucleoplasm appears indispensable for the development of CCA, whereas immediate activity of the oocyte genome is not required.

Amanitins↗
PubMed1975

Simultaneous assay of neutral sugars and amino sugars by an automatic sugar analyzer: applications to glycoproteins.

The simultaneous assay of neutral sugars and amino sugars commonly found in glycoproteins is described. The automatic sugar analyzer used for the determination is based on the ion-exchange chromatography of sugar-borate complexes on a strong anion-exchange resin. The sugars are identified with the orcinol/sulfuric acid reagent. While less than 40 nmol of mannose, fucose, galactose, glucose, xylose, or arabinose is sufficient for analysis at least 200 nmol mannosamine, glucosamine, or galactosamine is required; acidic monosaccharides cannot be determined. The technique of sugar analysis is applied to structural studies on natural compounds, e.g. the monosaccharide composition of lichenan and the carbohydrate moiety of the glycoproteins ovomucoid and Collocalia mucoid.

Amino Sugars↗
PubMedDate not supplied

The epidemiology of diabetic neuropathy. Diabetic Cardiovascular Autonomic Neuropathy Multicenter Study Group.

Although neuropathy has long been recognized as a complication of diabetes, the impact of this condition has not been adequately established. The prevalence of diabetic neuropathy is virtually unknown because the published studies differ considerably with regard to definition, method of assessment, and patient selection. Furthermore, the determination of prevalence has been hampered by the fact that there is no generally accepted classification of the variety of manifestations of diabetic neuropathy. The introduction of new sensitive diagnostic methods aids in the detection of less severe stages of neuropathy, as compared with clinically based assessment, and renders the disease more prevalent. The prevalence of diabetic neuropathy in the few reported population-based studies was approximately 30%. We have evaluated the prevalence of cardiovascular autonomic neuropathy in a group of approximately 1000 diabetic patients randomly included from 21 hospitals in Germany, Austria, and Switzerland. The results of this study and those of a prospective study on the natural history of neural dysfunction during the first 5 years after diagnosis of type 1 diabetes will be presented.

Adolescent↗
PubMedDate not supplied

Differential effects of near-normoglycaemia for 4 years on somatic nerve dysfunction and heart rate variation in type 1 diabetic patients.

To evaluate the long-term effects of near-normoglycaemia on somatosensory and autonomic nerve dysfunction, 55 poorly controlled Type 1 diabetic patients were allocated to intensified insulin treatment using continuous subcutaneous insulin infusion or multiple insulin injections and were studied prospectively for 48 months. They were divided into three groups according to their mean HbA1 levels during the study. Group 1 (n = 19) had mean HbA1 during months 3-48 in the normal range of less than 7.8% (near-normoglycaemic control), Group 2 (n = 18) showed moderately elevated mean HbA1 between 7.8 and 8.5% (satisfactory control), and Group 3 (n = 18) had clearly elevated mean HbA1 of greater than or equal to 8.6% (poor control). In the three groups studied, the changes in nerve conduction over baseline in the median and peroneal motor nerves as well as median and ulnar sensory nerves after 4 years were inversely related to the mean HbA1 levels of months 3-48 (all p less than 0.05). No significant associations with mean HbA1 were noted for the ulnar motor and sural sensory nerve conduction, vibration perception threshold, and heart rate variation. The percentages of patients with neuropathic symptoms decreased from 32 to 14% in Group 1, remained fairly constant in Group 2, and increased from 41 to 73% in Group 3 after 48 months when compared to baseline (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMedDate not supplied

Utility of skin testing in nutritional assessment: a critical review.

To evaluate the claim that delayed cutaneous hypersensitivity skin testing is useful in nutritional assessment of hospitalized patients, we reviewed the English language literature of the last 12 years. Although several hundred publications discussed delayed cutaneous hypersensitivity testing and nutritional status, only 15 provided new, objective data correlating these variables in hospitalized adults. Of these, only three provided age-matched control groups to control for antigen variability, lack of prior exposure, and other technical problems. The majority of reports took no account of diseases (cancer, immune disease, infection) or therapies (radiation, drugs, surgery) known to affect skin test response. In the reports specifying different degrees of malnutrition, the most important group, those with less than obvious malnutrition, were not abnormal by skin testing. Ten reports described serial skin testing during nutritional intervention. Non reported serially tested controls without nutritional intervention, important since serial testing alone can augment skin test response. Nonnutritional intercurrent therapy which might affect skin tests was seldom mentioned. In the few reports specifying that nutritional repletion was even achieved, repleted patients were not separated from unrepleted in subsequent analyses. No report examined skin testing for its predictive accuracy, cost/benefit ratio, or influence on outcome. Because of these problems in experimental design, the frequent lack of appropriate controls, and the low specificity of abnormal delayed cutaneous hypersensitivity responses, we conclude that the utility of skin testing in nutritional assessment remains unproved.

Humans↗
PubMedDate not supplied

Erythromycin facilitates postpyloric placement of nasoduodenal feeding tubes in intensive care unit patients: randomized, double-blinded, placebo-controlled trial.

BACKGROUND: To determine whether administration of erythromycin (E) could facilitate passage of a nasoenteric feeding tube into the duodenum for postpyloric feedings, this randomized, double-blind, placebo-controlled trial was performed. METHODS: Fifty-seven patients were accrued from the surgical intensive care units (ICUs) of a tertiary-care university hospital. Patients enrolled were categorized as to the presence or absence of diabetes mellitus (DM). Those patients without DM were then subdivided into those with normal or depressed mental status. The three groups, normal (NMS), depressed mental status (DMS), or diabetes mellitus (DM), were then randomized independently to receive either E or placebo (P), followed by blind placement of a feeding tube. Tube placement was verified by an abdominal radiograph. RESULTS: Overall, the rate of postpyloric placement was 61% (19/31) in the E group, significantly better than 35% (9/26) in the P group (p < .05). In patients with NMS, the success rate with E was improved (64%, 9/14) compared with that with P (9%, 1/11) (p < .0005). In the DMS group, there was a 50% success rate (6/12) with E versus 63% (5/8) with P (not significant [NS]). In the DM group, 80% (4/5) of the patients had placement of the tube in the duodenum with E and 43% (3/7) with P (NS). CONCLUSIONS: These data suggest that, overall, E is effective in facilitating placement of a nasoenteric feeding tube into the duodenum in ICU patients. It is clearly beneficial in those patients with normal mental status and may be useful in patients with diabetes mellitus.

Adult↗
PubMedDate not supplied

Aberrant stress response associated with severe hypoglycemia in a transgenic mouse model of Alzheimer's disease.

Patients with Alzheimer's disease (AD) exhibit alterations in glucose metabolism and dysregulation of the stress-responsive hypothalamic-pituitary-adrenal (HPA) neuroendocrine system. The mechanisms responsible for these alterations and their possible contributions to the neurodegenerative process in AD are unknown. We now report that transgenic mice expressing a mutant form of human amyloid precursor protein (APP) that causes inherited early-onset AD exhibit increased sensitivity to physiological stressors, which is associated with aberrancies in HPA function and regulation of blood glucose levels. Specifically, APP mutant mice exhibit severe hypoglycemia and death following food restriction, and sustained elevations of plasma glucocorticoid levels and hypoglycemia following restraint stress. The alterations in HPA function and glucose regulation were evident in relatively young mice prior to overt deposition of amyloid beta-peptide (A beta). However, diffuse accumulations of A beta were present in the hypothalamus of older mice, suggesting a role for soluble forms of A beta in dysregulation of HPA function. Our data demonstrate disturbances in neuroendocrine function in APP mutant mice similar to those seen in AD patients. These impairments in stress response, glucocorticoid signaling, and regulation of blood glucose should be considered in interpretations of data from past and future studies of APP mutant mice.

Alzheimer Disease↗
PubMedDate not supplied

Oedema extension in cerebral metastasis and correlation with the expression of nitric oxide synthase isozymes (NOS I-III).

BACKGROUND: The development of a peritumoral oedema is a common radiological sign in preoperative CT- and MRI scans of patients with cerebral metastasis. Large tumours can be accompanied by a marginally extended oedema and vice versa. Several cytokines (VEGF) have been identified as mediators of vascular induction and permeability. Transmitters such as nitric oxide (NO) have been identified as specific mediators of vascular dilation and tumour blood flow in primary brain tumours in which different NOS isozymes (NOS I and III) are induced as a result of the latent hypoxic metabolic scenery. Other authors have considered NO as an endothelial stabilising metabolite. Inducible NOS II is expressed by microglia and macrophages invading during tumour growth. At present, no data exist on NO synthesising enzymes in cerebral metastasis. MATERIALS AND PATIENTS: Cryosections (N = 96) of metastatic resections were investigated immunohistologically using a 4-step grading evaluation for the expression of NOS I-III, VEGF-receptor FLT-1, a pan-macrophage marker Ki-M1P, and capillary vessel presence by endothelial Von-Willebrand-Factor staining. The tumour and oedema extension was measured in preoperative MRI scans by an image processing device (Kontron) and calculated for the ratios of oedema volumes to total tumour volumes. The data were analysed statistically (Pearson Chi2 and Kruskal-Wallis analysis of variances) and correlated with the clinical data. Inducible NOS II was further investigated by in situ hybridization with a (4x30 mer) DNA oligoprobe cocktail. RESULTS: Between 1987 and 1996 289 patients in our department suffered from a metastatic disease in the brain or spinal cord. In 96 cases resected tumour material was processed for the immunohistological investigation. The age distribution ranged from 14 to 85 years with a median age of 58 years. The mean duration of symptoms before diagnosis was estimated as 53 days. The expression of NO synthase was frequently observed. NOS I was detected in 83.6%, gradings 2 and 3 in 40.5% of them. NOS III, the endothelial isoform, was observed in 39.4% (gradings 2 and 3), inducible NOS II in 29.4% (grading 2 and 3) of the specimens. The VEGF receptor FLT-1 could be detected in 70% of them, 24% in higher expression 2 and 3. The pan macrophage marker Ki-M1P was observed in 72% of all cases. Fifty seven percent of the specimens exhibited strong labelling with antibodies against VWF. Coexpressions were statistically significant for the VEGF receptor and NOS I-III (p < 0.01), Ki-M1P and NOS I and II (p < 0.05). A negative correlation was detected for the oedema index (oedema volume/total volume) and the labelling data for NOS III (r = -0.44, p = 0.13) and VEGF-R (r = -0.42, p = 0.022). No correlation existed for Ki-M1P, VWF and NOS I. CONCLUSIONS: The objective of the study was to investigate oedema morphometry, expression of NOS I-III and VEGF-R, presence of capillary vessels and macrophages in cerebral metastasis. A further aim was to investigate a putative oedema induction by NO producing isozymes. Nitric oxide synthase expression was statistically significantly correlated with the expression of the VEGF receptor and the presence of macrophages and microglia. There was a negative correlation between oedema extension and the presence of NOS III and VEGF-R. The results seem to indicate a specific oedema modulating role of NO in cerebral metastasis.

Adolescent↗