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Biomedical subjects

W Müller

Publications and source records attributed to W Müller.

At least 631 records · Page 35Linked to original sources
PubMed1986

New phase supports for liquid-liquid partition chromatography of biopolymers in aqueous poly(ethyleneglycol)-dextran systems. Synthesis and application for the fractionation of DNA restriction fragments.

New phase supports for liquid-liquid partition chromatography, using aqueous poly(ethyleneglycol)-dextran systems have been developed by grafting linear polyacrylamide chains on to premanufactured chromatographic supports carrying primary or secondary aliphatic hydroxyl functions on their surface. Columns prepared from such supports have a higher binding capacity for the dextran-rich stationary phase and much higher performances than columns prepared from cellulose, the previously used phase support for this system. Test separations of DNA restriction fragments, ranging from 11 base pairs to 3829 base pairs, document a high resolution for DNA fragments larger than 200 base pairs.

Base Composition↗
PubMed1986

Cell-cooling in flow cytometry by Peltier elements.

We have built a cooling device for cell suspensions in flow cytometry that makes use of the Peltier effect (Barnard RD, Thermo electricity in Metals and Alloys, Taylor and Francis, London; Siemens-Z 34:383-88, 1963). The prototype described here is used for cooling collection tubes during long-duration cell sorting and is capable of maintaining a temperature of 2-5 degrees C in a cell suspension of up to 3 ml. In general, Peltier element-based cooling is useful for equilibrating the temperature of small volumes of fluids. Furthermore, Peltier element-based cooling devices are easy to build and handle.

Animals↗
PubMed1986

Fluorescent styryl dyes applied as fast optical probes of cardiac action potential.

Several styryl dyes were tested as fast optical probes of membrane action potentials in mammalian heart muscle tissue. After staining, atrial specimens were superfused in physiological salt solution, and fluorescence was excited by an argon ion laser. Excitation spot size on the surface of the preparation was 60 microns in diameter. Dyes RH 160, RH 237, and RH 421 performed excellently as fast fluorescent probes of cardiac membrane potential. Fractional fluorescence changes, delta F/F, due to the action potential were in the range 2 to 6% at 514.5 nm excitation. Rise times of the action potential onset detected with each of the dyes were less than 0.5 ms, which is as fast or even faster than microelectrode measurements (atria of the rat). Thus membrane potential changes could be monitored with high resolution in both time and space. Emission spectra from heart muscle preparations stained with these dyes were shifted to shorter wavelengths by 70 nm and more as compared to spectra of the dyes in ethanol solution. The fluorescence spectrum of RH 160 at resting potential and the spectrum recorded during the plateau phases of the action potential were measured and showed no difference within the spectral resolution. As can be concluded from measurements of fluorescence changes at different excitation wavelengths, electrochromism cannot be the only mechanism causing the potential response.

Action Potentials↗
PubMed1986

Supratentorial lobar pilocytic astrocytomas: report of 45 operated cases, including 9 recurrences.

45 cases with supratentorial, lobar--mainly temporo-parietal--pilocytic astrocytoma are analysed. The mostly highly vascularized tumours frequently present with histologically different tissue components. Formation of cysts of various size was found in 67%. The tumour usually ran a benign clinical course with a comparatively low incidence of recurrence. Malignant transformation of recurrent tumours was not observed. Radiotherapy of conventional dosage did not prove to have any influence on survival, neither post-operatively nor after re-operation. Transformation of persisting pluripotential cells of the subependymal periventricular plate after migration to the surface of the brain is being discussed as the origin of this variant of pilocytic astrocytoma.

Adolescent↗
PubMed1986

Versatile kanamycin-resistance cartridges for vector construction in Escherichia coli.

To generate polylinker sequences which can be transferred together with an adjacent selectable marker, two plasmids (pWW-84 and pWW-97) were constructed which contain a kanamycin-resistance gene (KmR) flanked by various restriction sites. From these plasmids KmR-cartridges can be obtained as EcoRI, BamHI, SalI, AccI or HincII fragments for insertion into the appropriate restriction site of any plasmid. The following restriction sites can be introduced with these cartridges: BamHI, SalI (AccI, HincII), EcoRI, SacI, SphI and KpnI (Asp718) all adjacent to KmR, XhoI and HindIII, both within KmR. If desired, KmR can be removed by PstI digestion and religation, creating a single PstI site and leaving all adjacent sites intact.

Base Sequence↗
PubMed1986

Cow milk protein antigens and antibodies in serum of premature infants during the first 10 days of life.

Antigenic beta-lactoglobulin and alpha-casein were measured in the sera of 45 formula-fed infants of 31 to 41 weeks of gestation at 5 days and at 10 days of age. Quantitation was performed by a sensitive ELISA inhibition assay. On day 5 of life antigenic lactoglobulin was detected in 14 of 19 infants of less than 37 weeks gestation, but in only one of 10 infants of more than 36 weeks gestation. On day 10 of life the sera of all infants contained antigenic lactoglobulin. In contrast, on day 5 antigenic casein was present in four of 17 infants of less than 37 weeks gestation, but in 10 of 12 infants of the more mature group. On day 10 casein was detected in seven of 28 infants, with no difference between groups; anti-casein was found in eight of 12 infants. Infants of less than 37 weeks gestation have different absorption patterns than more mature infants do. "Gut closure" is an unlikely explanation for these findings.

Animals↗
PubMed1986

Class switch recombination is IgG1 specific on active and inactive IgH loci of IgG1-secreting B-cell blasts.

Mouse B lymphocytes can be activated polyclonally by bacterial lipopolysaccharide (LPS) to secrete Ig and perform Ig class switch. In the presence of the T-cell lymphokine B-cell differentiation factor, the frequency of IgG1-secreting cells is drastically enhanced. We show here that IgG1-secreting B cells isolated from such cultures have undergone a similar DNA rearrangement of the switch regions (S mu, S gamma 1) of the Ig heavy chain constant region genes C mu and C gamma 1 on both active and inactive IgH loci. This result argues against a stochastic model of class switch recombination and suggests programmed class-specific switch recombination in the case of the switch to IgG1. In accord with this notion, cells expressing IgM but not IgG on the surface have not deleted or rearranged C mu or S gamma 1 on either chromosome.

Animals↗
PubMed1986

Control of immunoglobulin class switch recombination.

The comparative analysis of Ig class switch recombination in a priori IgG/IgA-expressing myelomas and hybridomas, in switch variants and in activated normal B cells shows the following characteristics of class switch recombination in activated B cells: It is prevented during most of B cell ontogeny. It happens on both IgH loci of activated and switched B cells. The recombination is programmed in that on both IgH loci of switched cells the same switch regions recombine with Smu. This is true at least for the IgG1 pathway. IgM-expressing cells show no class switch recombination on the inactive IgH locus. Thus, physiological class switch recombination is a programmed rather than a random event and is controlled as such. The initial stages of class switching and the molecules involved in these are largely unclear: What is the nature of the protection of switch regions and how is this protection abrogated? Do specific recombinases exist? What is the role of large transcription units? Is the specificity of class switch recombination a result of specific "opening" of the DNA for transcription? Do all B cells use the same switch mechanism? What is the role of switch factors (such as lymphokines)? These and more questions await answers and although a variety of switch scenarios could be discussed at present a detailed speculation seems premature.

Animals↗
PubMed1986

Computer-aided electroretinography.

A description is given of a system of computer-aided electroretinogram (ERG) analysis. The system is the basis of a new quality in ERG evaluation. The statistical behavior of ERG components in healthy eye subjects is demonstrated by histograms. The new opportunities offered by the method are discussed.

Artificial Intelligence↗
PubMed1986

[Intravenous infusion of reproterol (a beta-2-mimetic agent) in the therapy of severe asthma attacks in childhood].

20 children (age range 0.8-14.7 years) with acute severe asthma were alternately randomized to receive one of two different treatment regimes. 10 children (control-group) received Salbutamol inhalation (75 micrograms/kg in 2 ml Saline every two hours). 10 children (reproterol-group) received reproterol infusion (0.2-2.0 micrograms/kg/min in Saline) and inhaled Saline only. Other therapy regimen were identical in both groups: Theophylline infusion, i.v. Prednisolone, adequate fluids intake and oxygen insufflation. Age, severity and maintenance therapy of asthma, and severity of the acute episode, were not significantly different in both groups. Treatment efficacy, assessed with a simple clinical score, the heart and respiratory rates, the peak expiratory flow (PEF) and the blood gases, was comparable in both groups. Side effects, i.e. tachycardia, blood pressure changes and tremor, were also similar and clinically not relevant in both groups. In two children, who previously needed repeated mechanical ventilation, severe respiratory failure could be successfully controlled only when the reproterol dose was raised 10 folds (2.0 micrograms/kg/min). Reproterol infusion can be recommended in children with acute severe asthma, who do not respond satisfactorily to current therapy regimen, particularly in children who previously experienced numerous intubations.

Adolescent↗
PubMed1986

[Hygiene in international animal transport].

Animal hygiene at international animal transport can be discussed with respect to three main aspects: The hygienic prevention of contagious diseases where at legislation is to be emphasized. As there are: import and transit regulations, origin and health certificates and precautious disinfection. Some of the latter show the particularity of the sea and air transport. By the means of contagious disease-legislation animals of the respective territory, but also the human are protected. In dependence of the duration of transport, either defined symptoms of a disease can be evident during the transport or at arrival in the destination-port, on the other hand animals can be still within incubation time. In the latter case only a quarantine at the destination can provide full efficiency. The curative veterinary aspect. In this special case is referred to experiences with "Enterotoxaemia" of sheep during sea-transportation. The disease leads to heavy losses of animals depending on the duration of the voyage (influence of stress of transport). Preventive measures, like vaccination at beginning of the transport and using superphosphate in the pens, depressed the losses persistent. The aspect of animal protection. Exemplary proposals for sufficient ventilation rates during air transport were given.

Aircraft↗
PubMed1986

[Problems of AIDS].

Explore the source record for details and available documents.

Acquired Immunodeficiency Syndrome↗
PubMed1986

Computer processed fluoroscopic images for digital intravenous renal angiography.

We investigated intravenous digital angiography using computer processed fluoroscopic images. Computer processed fluoroscopy (CPF) was compared to conventional digital subtraction angiography (DSA) in 39 patients referred for renal vessel evaluation. For assessment of CPF the anterior-posterior images were compared with the corresponding digital subtraction angiograms. 79% percent of DSA and 71% of CPF studies were diagnostic. Peripheral injection of contrast medium caused deterioration of CPF images. Skin dose measurements were obtained in 24 patients. The median dose for DSA was 8.2 rad, compared to 1.1 rad for CPF. It is concluded that sophisticated algorithms should be investigated for digital angiography, so that high image quality can be achieved with a reduced radiation exposure.

Adult↗
PubMed1986

[The tenacity of bacteria in the airborne state. IV: Experimental studies on the viability of airborne E. coli 0:78 under the influence of different temperature and humidity].

In a static aerosol chamber the tenacity of airborne E. coli 0:78 was determined at a permanent temperature of 22 degrees C and different relative humidities (10, 15-20, 30, 75 and 85%) and also at a permanent humidity of 30-40% and different temperatures (22, 28, 30, 34 and 40 degrees C). The greatest viability of the bacteria with a half-life-time of 390 min was found at 22 degrees C and 85% humidity. At 10% humidity the half-life-time was only 55 min. At a humidity of 30-40% the tenacity decreased from 37 to 14 min half-life-time, when the temperature increased from 22 to 40 degrees C. In preliminary examinations it could be shown that the method of cultivation and age of the bacterial suspension had an influence on the tenacity in the airborne state.

Air Microbiology↗