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Biomedical subjects

A Herrmann

Publications and source records attributed to A Herrmann.

At least 127 records · Page 7Linked to original sources
PubMed1993

Characterization of two different glycosylated domains from the insoluble mucin complex of rat small intestine.

The highly glycosylated domains of rat small intestinal mucins were isolated after reduction and trypsin digestion and separated into two populations (A and B) by gel chromatography. The molecular mass values were 650 and 335 kDa, respectively, and the relative yields suggest that the two glycopeptides occur in equimolar proportions. Electron microscopy revealed linear structures with weight average lengths of 230 nm (A) and 110 nm (B) corresponding to a mass/unit length of about 3 kDa/nm. The protein cores (17-19%) contain large amounts of threonine (over 40%), serine (17-24%), and proline (18-19%). Carbohydrate and sulfate account for approximately 80 and 0.5%, respectively, and gas chromatography-mass spectrometry showed that the patterns of neutral and sialic acid-containing glycans are very similar in the two glycopeptides. Both contain a significant amount (7-10 mol %) of single GalNAc residues, the average oligosaccharide is about 4 sugar residues long, and the largest species observed are heptasaccharides. The major neutral and sialic acid-containing oligosaccharides are Fuc1-2Gal1-3GalNAcol and GlcNAc1-6(NeuGc2-Gal1-3)GalNAcol, respectively. Sialic acid is present as both N-acetyl- and N-glycoloyl-neuraminic acid. Repeated extractions of the tissue with guanidinium chloride left approximately 80% of the mucus glycoproteins as an insoluble glycoprotein complex whereas exposure to dithiothreitol or high speed homogenization accomplished complete solubilization. The "subunits" obtained after reduction with dithiothreitol are larger than glycopeptides A and B, and fragments corresponding in size to the latter are obtained after cleavage with trypsin. Most of the mucins from rat small intestine thus occurs as an insoluble glycoprotein complex composed of subunits joined with disulfide bonds. The subunits contain two highly glycosylated regions with different lengths substituted with very similar oligosaccharides.

Amino Acids↗
PubMed1993

Mathematical modelling of lipid transbilayer movement in the human erythrocyte plasma membrane.

A model is presented to simulate transverse lipid movement in the human erythrocyte membrane. The model is based on a system of differential equations describing the time-dependence of phospholipid redistribution and the steady state distribution between the inner and outer membrane monolayer. It takes into account several mechanisms of translocation: (i) ATP-dependent transport via the aminophospholipid translocase; (ii) protein-mediated facilitated and (iii) carrier independent transbilayer diffusion. A reasonable modelling of the known lipid asymmetry could only be achieved by introducing mechanism (iii). We have called this pathway the compensatory flux, which is proportional to the gradient of phospholipids between both membrane leaflets. Using realistic model parameters, the model allows the calculation of the transbilayer motion and distribution of endogenous phospholipids of the human erythrocyte membrane for several biologically relevant conditions. Moreover, the model can also be applied to experiments usually performed to assess phospholipid redistribution in biological membranes. Thus, it is possible to simulate transbilayer motion of exogenously added phospholipid analogues in erythrocyte membranes. Those experiments have been carried out here in parallel using spin labeled lipid analogues. The general application of this model to other membrane systems is outlined.

Adenosine Triphosphate↗
PubMed1993

Enhancement of viral fusion by nonadsorbing polymers.

Nonadsorbing polymers such as dextran and poly(ethylene glycol) enhance binding as well as extents of fusion of influenza virus with erythrocytes. Kinetics and extent of viral membrane fusion were measured using an assay based on lipid mixing of a fluorescent dye. The effects of nonadsorbing polymers were in the concentration range from 0 to 10 wt%, far below the concentration required to overcome hydration repulsion forces. The enhancing effects were dependent on the molecular weight of nonadsorbing polymer, and only occurred at molecular weight > 1500; this links the phenomena we observe to the so-called "excluded volume effect" of nonadsorbing polymers. The time delay between triggering and the onset of influenza virus fusion was significantly reduced in the presence of nonadsorbing polymers. High molecular weight poly(ethylene glycol) also induced fusion of vesicular stomatitis virus with intact erythrocytes, which do not serve as target of vesicular stomatitis virus fusion in the absence of the polymer. The forces between membranes which determine rate-limiting processes in viral fusion and how they are affected by nonadsorbing polymers are discussed.

Adsorption↗
PubMed1993

Dental status and oral hygiene in patients with head and neck cancer.

Poor oral hygiene is believed to play a role as a risk factor for head and neck cancer, especially for oral cancer. Only few epidemiologic data exist about dental status and oral hygiene in these patients. We performed a case-control study involving 100 patients with squamous cell carcinoma of the upper aerodigestive tract and 214 age- and sex-matched control subjects with no known tumorous disease. In the tumor patients, oral hygiene and dental status proved to be significantly worse: the majority of the tumor patients seldom or never brushed their teeth and the frequency of dental visits was significantly lower. Tartar of 3 mm or more was found in 40.9% of the tumor patients and in 22% of the control subjects. In the tumor group, the incidence of decayed teeth was significantly higher compared with the control subjects. Chronic inflammation of the gingiva was observed in 28% of the tumor patients vs. 13.5% in the control group. Oral hygiene was negatively correlated with alcohol as well as with tobacco consumption. The social status of subjects also correlated with oral hygiene, which was found to be worst in subjects from the lower social strata. The present study revealed a poor dental status and oral hygiene in patients with head and neck cancer. The pathogenetic mechanism being associated with this suspected risk factor remains to be investigated.

Adult↗
PubMed1993

[Daily "routine chest x-ray" in ventilated surgical intensive care patients].

We investigated the relevance of daily routine chest x-ray in intensive care for therapeutical decision. A special emphasis was put on clinical laboratory parameters according to the APACHE-II-score. Within a prospective study we investigated 40 intubated patients of our surgical intensive care unit with a total of 609 x-ray films. 26% of all pictures gained influence on therapeutical procedure. Analysis of different patient subgroups showed only between those under 50 and those above 70 years of age an important discrepancy quote of relevant films (19 vs. 31%).

Adult↗
PubMed1992

The influence of dextran sulfate on influenza A virus fusion with erythrocyte membranes.

Dextran sulfate suppresses the low pH-induced fusion of influenza virus A/Brazil 11/78 with erythrocyte membranes, as shown by fluorescence dequenching assay, using the fluorophore octadecylrhodamine B chloride (R18). Inhibition of fusion was maximal at pH 5.0, while at higher pH values (> 5.6) fusion was not affected. Hemolysis of intact red blood cells by influenza A virus at low pH values is also prevented by dextran sulfate. The inhibiting effect of the polymer is mainly ascribed to repression of virus attachment. Evidence is given that the conformational change of the virus envelope protein hemagglutinin (HA) responsible for triggering fusion is not affected by the polymer.

Anilino Naphthalenesulfonates↗
PubMed1992

The role of phospholipid asymmetry in calcium-phosphate-induced fusion of human erythrocytes.

To elucidate the role of phospholipid asymmetry in calcium-phosphate-induced fusion of human erythrocytes, we examined the interaction of erythrocyte membranes with asymmetric and symmetric bilayer distributions of phospholipids. Fusion of human erythrocytes was monitored by light microscopy as well as spectrophotometrically by the octadecylrhodamine dequenching assay. Phospholipid translocation and distribution between the inner and the outer leaflet of intact red blood cells were determined with spin-labeled phosphatidylserine (PS), phosphatidylethanolamine (PE), and phosphatidylcholine (PC). Significant fusion of lipid-asymmetric red blood cells where PS and PE are predominantly oriented to the inner leaflet was only observed at Ca2+ concentrations greater than or equal to 10 mM (in the presence of 10 mM phosphate buffer) while fusion of lipid-symmetric erythrocyte membranes was established at greater than or equal to 1.5 mM Ca2+. The Ca2+ threshold of fusion of lipid-asymmetric red blood cells was significantly reduced (i) after exposure of PS to the outer layer but not after redistribution of PE alone, and (ii) upon incorporation of spin-labeled PS into the outer leaflet of red blood cells. Spin-labeled PE or PC did not affect fusion, suggesting that the serine headgroup is an important factor in calcium-phosphate-induced fusion.

Calcimycin↗
PubMed1992

ph-dependent hydrophobicity profile of hemagglutinin of influenza virus and its possible relevance in virus fusion.

The hydropathy profile of hemagglutinin (HA) subunits HA1 and HA2 of influenza virus X31 and A/PR 8/34 is analyzed at different pH. At neutral pH (7.4) pronounced hydrophobic sequences of HA correspond to the N-terminus and the transmembrane spanning sequence of HA2. At pH 5.0 where influenza virus is known to fuse with biological membranes several hydrophobic sequences in the ectodomain exist which are comparable in both the hydrophobicity and length of the N-terminus of HA2. It is suggested that these hydrophobic stretches are important for the fusion complex, in addition to the N-terminal site of HA2.

Hemagglutinins↗
PubMed1992

The combined masseter muscle/intraoral cheek transposition (IOCT) flap for primary reconstruction of the dorsal oral cavity.

A method for primary reconstruction of the dorsal oral cavity after tumor resection of T2 or small T3 tumors is presented. By combination of the masseter muscle flap with a cranial pedicled intraoral cheek transposition (IOCT) flap, a reconstruction of the defects with two layers of tissue is possible. This easy and functional reconstruction method is especially useful for high-risk patients because of the markedly reduced operating time.

Aged↗
PubMed1992

[Septic granulomatosis (chronic granulomatous disease = CGD) in the jaw area. A case report].

A rare case of chronic granulomatous disease with manifestation in the mandible is presented. A 10-year-old boy showed the clinical picture of osteomyelitis without paresthesia (Vincent syndrome). Diagnosis was done by the nitroblue tetrazolium test (NBT) and by demonstration of a complete cytochrome-b deficiency of the granulocytes. In septic granulomatosis a continuous application of Sulfamethoxazol-Trimetoprim is recommended for prophylaxis of infection. For treatment of infection further antibiotics who pass into the granulocytes like rifampicin and fosfomycin are necessary. Oral surgical procedures request a careful tissue handling and a tight wound closure.

Child↗
PubMed1991

Interaction of influenza hemagglutinin amino-terminal peptide with phospholipid vesicles: a fluorescence study.

We have studied tryptophan fluorescence from a 20-residue synthetic peptide corresponding to the amino terminal of the HA2 subunit of the influenza virus hemagglutinin protein, a putative "fusion" peptide. Decay-associated spectra have been obtained at pH 7.4 and at pH 5 (the optimal pH for influenza virus fusion) in the presence and absence of liposomes. We demonstrate that a blue shift in the total steady-state fluorescence spectrum upon binding to liposomes is due to a movement in characteristic emission wavelength and increased lifetime of one of the resolved spectral components. In contrast, a further shift after lowering the pH is the product of a redistribution in the relative amplitudes of spectral components. Also, each decay component is quenched by spin-labels or anthroxyl groups normally located within the hydrocarbon interior of the membranes. Calculations are presented leading to an estimate of the distance of the tryptophan residue from the bilayer center, suggesting that the tryptophan residues are at or near the hydrocarbon-polar interface. No gross positional change was detected between pH values. Rotational depolarization is shown to be retarded by liposome binding, more so at low pH.

Amino Acid Sequence↗
PubMed1991

35S-beta-glucuronidase gene blocks biological effects of cotransferred iaa genes.

The iaaM and iaaH genes of Agrobacterium tumefaciens and Agrobacterium rhizogenes play an important role in crown gall and hairy root disease. The iaaM gene codes for tryptophan monooxygenase which converts tryptophan into indole-3-acetamide (IAM). IAM is converted into the auxin indole-3-acetic acid (IAA) by indoleacetamide hydrolase, encoded by the iaaH gene. In functional studies on the activity of the iaa genes of the TB region of the A. tumefaciens biotype III strain Tm4, the frequently used 35S-beta-glucuronidase (35S-UidA or GUS) marker gene was found to inhibit IAA synthesis and root induction encoded by the TB iaa genes. To exert this inhibition, the 35S-UidA gene must be cotransferred with the iaaH gene. The 35S promoter alone is sufficient to cause the inhibitory effect.

Amidohydrolases↗
PubMed1991

[Frey's syndrome (gustatory sweating) after fracture of the temporomandibular joint].

Damage of the auriculo-temporal nerve with consecutive Frey's syndrome (gustatory sweating) can occur with fractures of the temporomandibular joint (TMJ) as a result of the anatomic proximity. A case of marked gustatory sweating as a rare complication of a mandibular joint fracture and alternation of therapy are reported.

Fracture Fixation, Internal↗
PubMed1991

Parotid sialography with a new Zonarc program.

The use of panoramic zonography with the Zonarc-MLA and LAT-PA program for parotid sialography is presented. It provides curved layer tomograms, and shadows of the bony structures are therefore not disturbingly superimposed on the image of the sialogram. The visibility in the retromandibular region tended to be better. Radiation doses in plain film radiography are up to 60 times higher than in Zonarc radiography.

Aged↗
PubMed1991

Calcium phosphate-induced fusion of human erythrocyte ghosts monitored by dilution of a membrane bound fluorescence probe.

Calcium-phosphate induced fusion of human erythrocytes was investigated using an assay based on the relief of the fluorescence selfquenching of a fluorescent amphiphile incorporated into ghost membranes as it occurs when labeled membranes are fused with unlabeled membranes. Measuring ghost fusion up to Ca(2+)-concentrations of 4 mM in the presence of 10 mM phosphate, both an acceleration of the fusion process and an enhancement of the fusion extent with increasing amounts of calcium were observed. Fusion takes place even in the case when calcium-phosphate complexes were formed in the suspension medium prior to the addition of ghosts. These results are in contrast to previous observations, obtained by an internal aqueous content mixing assay, where fusion of ghosts was inhibited at Ca(2+)-concentrations greater than 1.75 mM, and preformed calcium-phosphate complexes were not able to induce fusion. The results point to the necessity of utilizing content mixing assays in conjunction with the lipid dilution assay to get a more detailed insight in membrane fusion mechanism(s).

Adenosine Triphosphate↗
PubMed1991

[Panoramic zonography in the diagnosis of TMJ fractures].

The radiological diagnosis of fractures of the mandibular condyle may be quite difficult. In a study of 237 patients the value of panoramic zonography is evaluated. Advantages of the new method are orthoradial projection, examination in a supine position, and good visibility of the anatomical structures in the TMJ-S and TMJ-PA program. Radiation doses in conventional radiography are 40-60 times higher than in panoramic zonography. High resolution CT should be reserved for special indications.

Humans↗
PubMed1991

Regulatory elements required for light-mediated expression of the Petroselinum crispum chalcone synthase gene.

Chalcone synthase (CHS) catalyzes the committed enzymatic step in flavonoid biosynthesis. In parsley (Petroselinum crispum), CHS is encoded by a single gene locus. Transcriptional activation of the gene in response to UV-containing white light has been demonstrated. Analysis of the CHS gene promoter by in vivo footprinting revealed four short sequences, designated Boxes I, II, III, and IV, which contain guanosine residues with altered reactivity to the methylating agent dimethylsulfate in UV-treated versus untreated parsley cells. Studies were performed to characterize the functional components of the CHS gene promoter using a parsley protoplast transient expression system. By deletion and block-mutation analyses it was shown that Boxes I and II act together as a cis-acting unit and are necessary components of the minimal, light-responsive CHS gene promoter. The Box II sequence, which is similar to the conserved G Box sequence defined in promoters of ribulose 1,5-bisphosphate carboxylase small subunit (RBCS) genes, has been subjected to detailed analysis by site-directed mutagenesis. The heptameric sequence 5'-ACGTGGC-3' has been defined as the critical core of Box II required for light induction in the context of the CHS gene minimal promoter. Box II is functionally equivalent to a second, sequence-related element (Box III) that can replace Box II in an orientation-dependent manner. Chimaeric promoter-fusion constructs to the GUS reporter gene demonstrated that Boxes I and II, together constituting a cis-acting unit, are necessary and sufficient for light-mediated activation of the CHS gene promoter.

Acyltransferases↗