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H Schott

Publications and source records attributed to H Schott.

At least 91 records · Page 5Linked to original sources
PubMed1984

[Isolation of oligonucleotides from partial hydrolysates of DNA using template chromatography].

Purine oligonucleotides are adsorbed at 0 degree C on poly(vinyl alcohol)-p(dC)n-DEAE-cellulose, and pyrimidine oligonucleotides on oligo(guanylic acid) gel according to the base-pairing mechanism, if their sequences contain at least three or more homologous, consecutive guanylic or cytidylic moieties. By increasing the temperature all base-paired oligonucleotides are desorbed. With this template chromatography mixtures of defined purine- or pyrimidine oligonucleotides could be isolated from fractionated partial hydrolyzates of herring sperm DNA. Afterwards these mixtures are rechromatographed on QAE-Sephadex and/or Nucleosil C18. Using this approach oligonucleotides up to nine monomer units can be isolated either as single substances or as mixtures with defined composition on a preparative scale, which would be not possible with the already existing separation procedures when partial hydrolyzates of herring sperm DNA as starting material are used. Purity and sequence of the isolated oligonucleotides are determined by the "fingerprint" method.

Animals↗
PubMed1984

[Preparative isolation of tetra-, penta- and hexapurine oligonucleotides from partial hydrolysates of depyrimidinated herring sperm DNA].

Herring sperm DNA is chemically degraded to a complex mixture of purine nucleotides. The oligonucleotides are separated from the partial hydrolysates by column chromatography. The resulting mixture of trimer to hexamer purine oligonucleotides is subsequently fractionated on QAE-Sephadex into different mixtures of sequence-isomeric purine oligonucleotides. In a final separation, which uses reversed-phase (Nucleosil C18) high-performance liquid chromatography, these mixtures are separated under isocratic conditions into 35 pure defined purine oligonucleotides with four to six monomer units, 14 defined mixtures of sequence-isomeric purine oligonucleotides and several unidentified products. Purity and sequence of the isolated oligonucleotides are determined by the "fingerprint" method. The results of the high-performance liquid chromatographic and the "fingerprint" methods of the isolated oligonucleotides are discussed.

Animals↗
PubMed1984

[Preparative isolation of hexa-, hepta-, octa-, nona- and decapyrimidine oligonucleotides from hydrolysates of depurinated herring sperm DNA].

The pyrimidine oligonucleotides (dT)5; (dT)6 and the mixtures of sequence isomers (dC, dT5); (dC2, dT5); (dC3, dT4); (dC4, dT3); (dC4, dT4); (dC3, dT5); (dC2, dT6); (dC4, dT5); (dC3, dT6); (dC2, dT7); (dC5, dT5); (dC4, dT6) and (dC3, dT7) with or without terminal phosphate groups have been isolated on a preparative scale from hydrolysates of depurinated herring sperm DNA by the following procedure. Herring sperm DNA (1 kg) is chemically depurinated and partially hydrolysed to a mixture of pyrimidine nucleotides. The partial hydrolysate is first separated into a low- and a high-molecular-weight pyrimidine nucleotide mixture by column chromatography on DEAE-cellulose. The mixture of high-molecular-weight pyrimidine nucleotides is subsequently fractionated on QAE-Sephadex. Impurities which are not fully removed by column chromatography are separated by paper chromatography. The compositions of the mixtures of sequence isomers are determined from the data of column, paper and homochromatography; from absorption characteristics and by enzymatic degradation.

Animals↗
PubMed1984

Colorimetric prednisolone assay and its application to dissolution studies.

The colorimetric method of Porter and Silber, originally developed for assaying cortisone and related corticosteroids, was adapted to the assay of prednisolone in the presence and absence of a surfactant, octoxynol 9. Optimal conditions for the colorimetric reaction between prednisolone and acidified phenylhydrazine solution were 30 min at 50 degrees C. The slight interference of octoxynol 9 with the absorbance of the yellow prednisolone-phenylhydrazine complex at 410 nm was corrected by adding an equal surfactant concentration to the blank. When freshly prepared acidified phenylhydrazine solutions were used, the colorimetric method had a sensitivity of 0.2 microgram/mL and a precision of 0.1 microgram/mL. Its averaged relative standard deviation was 3.7% in the prednisolone concentration range of 10-300 micrograms/mL.

Colorimetry↗
PubMed1984

Solubility parameter and hydrophilic-lipophilic balance of nonionic surfactants.

The solubility parameters of various polyoxyethylated nonionic surfactants were compared with their hydrophilic-lipophilic balance (HLB) numbers. The compounds included three homologous surfactant series based on dodecanol, octylphenol, and fatty acid esters of sorbitan, respectively, a polyoxyethylated sorbitol ester, and a polyethylene glycol. Solubility parameters were calculated from measured heats of vaporization for the polyoxyethylated dodecanol series and from molar attraction constants for all three surfactant series. The values remained nearly constant and independent of the degree of polyoxyethylation, increasing at most by 1 (cal/cm3) 1/2 while the HLB increased from 0 to 10. This discrepancy arose because HLB values are based on emulsification experiments, in which the polyoxyethylene or polyol moiety of the surfactants is hydrated, while the solubility parameter was calculated for anhydrous conditions. When the solubility parameter was corrected for hydration by including a hydrogen-bonding component, plots of HLB versus this new solubility parameter were nearly linear and parallel for the three series of surfactants, with slopes of 5.0 +/- 0.2. The three lines were spaced apart only approximately 1.2 (cal/cm3) 1/2 despite structural differences among the surfactants, indicating that the chemical nature of the hydrocarbon moiety exerts only a limited effect on the solubility parameter. The HLB, which considers only the weight percent of the hydrocarbon moieties of nonionic surfactants and completely disregards differences in structural features, is, therefore, not as bad an approximation as had previously been thought.

Chemical Phenomena↗
PubMed1984

Effect of inorganic additives on solutions of nonionic surfactants VI: Further cloud point relations.

Disperse dosage forms stabilized with nonionic surfactants frequently contain electrolytes as active ingredients or adjuvants. Salting out of the surfactants by these electrolytes may cause breakdown of the dosage forms. The cloud point of an aqueous solution of octoxynol 9 was used to measure the salt effects. Electrolytes which salt octoxynol 9 out lower its cloud point, while salting-in electrolytes raise it. The observed cloud point effects are discussed according to the mechanisms involved. Salting out by dehydration in competition with octoxynol 9 for the available water was observed with sulfate and phosphate anions, sodium, potassium, and ammonium tribasications, and the nonelectrolyte sorbitol. The extensive self-association of water by hydrogen bonds at and below room temperature weakens its solvent power. Ions which reduce this self-association, breaking the structure of water, increased the cloud point of octoxynol 9. Among them were the iodide, thiocyanate, and nitroprusside anions. Ions which tighten the structure of water and enhance its self-association salted the surfactant out, lowering its cloud point. Among these were the fluoride and hydroxide anions. Complex formation between the ether linkages of octoxynol 9 and the following cations increased its cloud point: hydrogen (from strong acids), silver, magnesium, and zinc. Including published data, the only cations which do not form complexes with polyoxyethylated surfactants (and are, therefore, unable to salt them in) were the alkali metal ions sodium, potassium, and cesium and the ammonium ion.(ABSTRACT TRUNCATED AT 250 WORDS)

Acids↗
PubMed1984

Isolation and functional property of mRNAs coding for human interleukin 2.

Interleukin 2 (IL 2) is a lymphokine with specific growth promoting properties for activated T cells. The isolation and purification of specific mRNAs coding for this protein is reported. The analysis of total poly A + containing RNA from PHA stimulated T lymphocytes on agarose gels reveals the existence of at least two different IL-2 mRNAs. Isolated RNAs have been microinjected separately into Xenopus laevis oocytes for translation and consecutively the synthesized proteins were tested for activity on alloactivated T cell lines which were dependent on IL-2 for growth. Both RNAs coded for a protein which displayed clearly detectable IL-2 activity.

Animals↗
PubMed1984

[Surgical indications in craniofacial injuries].

Precise definition of indications for surgery in patients with craniofacial injury is impossible, and individual assessment of each case by the surgeon can be a source of errors. These may be due to excess or omission when confronted with bone lesions which fail to supply information on the state of the dura mater, and with rhinorrhea with lack of sufficient criteria to assess the condition of the dura mater and its capacity for healing. Indications should therefore be modulated as a function of the different anatomoclinical types involving different risks. On the other hand, one should not search for perfection since other factors are involved when operating under emergency conditions, and one must not err by presumption, knowing that no reconstruction is perfect.

Craniocerebral Trauma↗
PubMed1983

[Preparative isolation of mono-, di- and tripurine nucleotides from hydrolysates of depyrimidinated herring sperm DNA].

The purine nucleotides pdAp, pdGp, (dA)2, (dA-dG), (dG-dA), (dG)2, (dA)3, (dA-dG-dA), (dA-dA-dG), (dG-dA-dA), (dG-dA-dG) and known mixtures of purine nucleotide sequence isomers were separated by preparative scale chromatography of partial hydrolysates of depyrimidinated herring sperm DNA. Herring sperm DNA is first partially hydrolysed to a mixture of purine nucleotides. The low-molecular-weight oligonucleotides are then separated by column chromatography on DEAE-cellulose at pH 7.5, and fractionated by chromatography on QAE-Sephadex. Impurities which are not fully removed by column chromatography are separated by paper chromatography. The sequence of the isolated DNA fragments and the composition of the mixtures of sequence isomers were determined from the chromatographic data, absorption characteristics and by enzymatic degradation.

Animals↗
PubMed1983

Improved microscopic techniques for droplet size determination of emulsions.

A novel, disposable cell for microscopic determination of the droplet size of emulsions is described. It is made from a piece of adhesive tape in which a hole has been punched which is placed between a glass slide and a cover glass. This cell is easier to fill with emulsions thickened to reduce Brownian motion and creaming than commercial counting chambers, and it prevents field flow. Droplet size averages and distributions obtained with this cell and another counting chamber agreed, provided that the emulsion viscosity was approximately 20 cp or higher. The sample size required to provide arithmetic mean diameters with a specified accuracy at a preselected confidence probability was calculated.

Emulsions↗
PubMed1983

Effect of inorganic additives on solutions of nonionic surfactants V: Emulsion stability.

Electrolytes often break emulsions to which they were added as active ingredients, adjuvants, or impurities. The stability of oil-in-water emulsions containing octoxynol 9 NF as the emulsifier and various added electrolytes was investigated by measuring droplet size, turbidity, and oil separation on storage at various temperatures and in a centrifugal field at 25 degrees. Electrolytes were added to hexadecane emulsions after emulsification (direct addition); alternatively, hexadecane was emulsified in octoxynol 9-electrolyte mixtures (reverse addition). Xylene emulsions were prepared by direct addition only. Hexadecane emulsions containing 0.10% octoxynol 9 were considerably more stable than xylene emulsions containing 0.60% because the surfactant is practically insoluble in hexadecane, but miscible in all proportions with xylene. An emulsifier soluble in the disperse phase as well as the continuous phase evidently forms less stable interfacial films. The electrolytes investigated were sulfuric and hydrochloric acids, magnesium nitrate, and aluminum nitrate, which salt octoxynol 9 in by complexation between its ether groups and their cations; sodium thiocyanate, which salts the surfactant in by destructuring water; and sodium chloride and sodium sulfate, which salt octoxynol 9 out. The addition of these electrolytes at concentrations up to 2 or 3 m to hexadecane emulsions produced fast and extensive creaming, little or no flocculation, no coalescence, and only minor changes in droplet size or turbidity on storage at room temperature. The extent of coalescence during centrifugation was actually reduced by the additives. Such stability is unusual. Droplet size and turbidity depended mainly on octoxynol 9 concentration. The greatest decrease in the former and increase in the latter occurred when the concentration was increased from 0.10 to approximately 0.4%. All emulsions became slightly coarser on storage at 25 degrees. Stability at 50 degrees was impaired by aluminum nitrate and magnesium nitrate and to a lesser extent by sodium sulfate and sodium chloride. Reverse-addition emulsions differentiated better between the electrolytes than direct-addition emulsions. Electrolytes salting octoxynol 9 in, especially by complexation, generally produced the finest and most stable emulsions. Similarly, xylene emulsions were destabilized more by the electrolytes which salted the emulsifier out than by those salting it in. Centrifugation of hexadecane emulsions at 7800 X g compressed the creamed emulsion layer into a plug of clear, transparent, isotropic gel from which coalesced hexadecane separated slowly on further centrifugation.(ABSTRACT TRUNCATED AT 400 WORDS)

Chemical Phenomena↗
PubMed1982

The role of surfactants in the release of very slightly soluble drugs from tablets.

The ability of surfactants to accelerate the in vitro dissolution of very slightly soluble drugs has been ascribed to wetting and/or micellar solubilization. Deflocculation as a mechanism to accelerate dissolution has not been investigated. In the present study, the effect of a surfactant on the dissolution kinetics of prednisolone from tablets and the mode of action of the surfactant were investigated. The dissolution of prednisolone at 37 degrees in 0.1 N HCl containing different concentrations of the nonionic surfactant, octoxynol 9, followed zero-order kinetics. The rate constant was increased by 15, 150, and 950% when octoxynol was added to the dissolution medium at 0.0039 and 0.032% (approximately 0.5 and 4.0 times the critical micelle concentration) and incorporated into the tablets (for a final concentration of 0.0039%), respectively. The surface tensions of the dissolution media were 71, 35, and 31 dyne/cm for 0, 0.0039, and 0.032% octoxynol, respectively. The largest decrease in surface tension corresponded to the smallest increase in dissolution rate, indicating that wetting was unimportant. The micellar solubilization capacity of octoxynol was much too small to account for the increases in dissolution rate. Microscopic particle size measurements and sedimentation volume determinations showed the pronounced deflocculation of prednisolone by the surfactant. The observed increases in specific surface area at the two octoxynol concentrations were in good quantitative agreement with the increases in dissolution rate according to the Noyes-Whitney equation.

Chemistry, Pharmaceutical↗
PubMed1982

Solubility parameter, specific molar cohesion, and the solubility of ethylene oxide in polymers.

The polarity of polymers is commonly characterized by their solubility parameter to describe their interaction with small molecules or by their specific molar cohesion to describe interchain attraction. A linear relation between these two parameters is demonstrated. Ethylene oxide (EO) is used to sterilize containers and devices containing plastics or elastomers. The solubility parameter concept is applicable to the sorption of EO by such polymers provided crystallinity and rubbery/glassy state are taken into account. The delta value of EO, calculated from the temperature dependence of its vapour pressure, is 10.8 (cal/cm3)1/2. The highest EO solubility is in polyvinyl chloride and polycarbonate, whose solubility parameters match that of EO closely. The solubility in other polymers decreases as their solubility parameters diverge increasingly from 10.8. At comparable delta values, polymers in the rubbery state dissolve 6000 to 8000 ppm EO more than polymers in the glassy state. EO solubility in the amorphous fraction of polymers above their glass transition temperatures ranges from 20 800 ppm for plasticized polyvinyl chloride (delta = 9.2) to 800 ppm for polytetrafluorethylene (delta = 6.2).

Ethylene Oxide↗
PubMed1982

[Not Available].

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Cocaine↗
PubMed1982

[Differential diagnosis of pancreatitis: metastasis to the pancreas].

A case report is given of a patient with a metastasizing teratocarcinoma of the testis (ripe teratoma and embryonal carcinoma), which was misinterpreted in the beginning as acute pancreatitis. At post mortem, metastases of this tumour were found in the pancreas, which apparently had led to inflammatory lesions of this organ, which could not explain however all of the clinical symptoms seen before. The literature dealing with cases suffering from acute pancreatitis induced by tumours is reviewed. A list of possible associations between pancreatitis and tumours is given.

Acute Disease↗