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Biomedical subjects

G Hahn

Publications and source records attributed to G Hahn.

At least 19 recordsLinked to original sources
PubMed1992

Enantiospecific high-performance liquid chromatographic assay with fluorescence detection for the monoamine oxidase inhibitor tranylcypromine and its applicability in pharmacokinetic studies.

In order to be able to measure low concentrations of tranylcypromine enantiomers in biological material, chiral fluorescent derivatization and high-performance liquid chromatography (HPLC) were employed. The internal standard S-(+)-amphetamine and borate-sodium hydroxide buffer pH 11 were added to plasma or urine sample aliquots. o-Phthaldialdehyde was used for precolumn derivatization in combination with the chiral mercaptan N-acetylcysteine. HPLC resolution of the diastereoisomeric derivatives was possible on an octadecylsilane column. The mobile phase consisted of sodium phosphate buffer solution pH 6.5, methanol and tetrahydrofuran. The fluorescence of the eluate was monitored at 344/442 nm. The intra-day coefficients of variation were below 10%, the limit of determination was 0.5 ng/ml. The assay was found to be applicable for routine analyses in a preliminary pharmacokinetic study, in which an oral dose of 20 mg racemic tranylcypromine sulfate was administered to three healthy volunteers. The plasma concentrations were generally low, and those of S-(-)-tranylcypromine significantly exceeded those of the R-(+)-enantiomer. Average maximum concentrations were 57.5 and 6.3 ng/ml for S- and R-tranylcypromine, respectively. While S-tranylcypromine was well detectable within the whole study period (8 h), R-tranylcypromine concentrations fell below the detection limit after 4 h in two out of the three studied volunteers.

Chromatography, High Pressure Liquid↗
PubMed1991

Rapid assay for the quantification of piretanide in biological fluids.

Piretanide was determined from plasma and urine using reversed-phase high-performance liquid chromatography. Plasma was extracted with diethylether at pH 4 using bumetanide as internal standard. The chromatographic separation was performed on an octadecylsilane column (ODS) with acetonitrile/pH 7 phosphate buffer (3:7, v/v). In order to determine piretanide in urine, bumetanide was added to a urine aliquot. Then the sample was centrifuged and the supernatant directly injected without extraction followed by chromatography on an ODS column with a mixture of methanol and pH 7 phosphate buffer (12:13, v/v). The compounds were detected by their intrinsic fluorescence, monitoring the eluate at 287/450 nm. Total chromatography times were 8 min for plasma and 13 min for urine samples. The method was applied for the assay of piretanide in plasma of healthy volunteers after i.v. or p.o. dosage of 6 mg piretanide.

Administration, Oral↗
PubMed1991

Comparison of chromogenic and fluorogenic substances for differentiation of coliforms and Escherichia coli in soft cheese.

In food hygiene the differentiation of Escherichia coli and coliforms as index resp. indicator organisms is very important as a basis for the assessment of good manufacturing practice (gmp). Using a fluorogenic (MUG) and chromogenic (X-gal) substrate the laborious methods have become more simple and reliable. A new German DIN standard method (10.183, part 3) was used as a base to examine 200 soft cheese samples for coliforms and Escherichia coli comparing different media, parameters and incubation times. It could be shown that an incubation of 48 h is absolutely necessary for E. coli and coliforms in both media, that X-gal is a quicker and more sensitive parameter for total coliforms than gas production and that the combination of fluorescence and indole is slightly superior to fluorescence and gas for the identification of E. coli. To sum up, the new fluorescence principle, integrated in new standard methods will be an excellent tool to simplify the differentiation of E. coli and coliforms in food hygiene. Additionally, X-gal as a chromogenic substrate for all coliforms, including E. coli, may be integrated in further standard methods.

Bacteriological Techniques↗
PubMed1979

Erythromelalgia.

Erythromelalgia is an extraordinary disorder of unknown etiology and pathophysiology that resembles the post-traumatic reflex dystrophy syndromes but has not been described previously in the orthopedic literature. Its distinctive triad of intense burning extremity pain associated with erythema and increased skin temperature are diagnostic. Primary or idiopathic and a secondary or associated form have been identified. The latter occurs in association with an underlying disease process, especially myeloproliferative disorders. Treatment with pharmacologic agents and surgery are ineffective except in the secondary group where treatment of the associated disorder generally results in a remission. Symptoms in the primary group can be minimized by appropriate environmental control with cooling and avoiding heat-producing situations that would raise skin temperature above a critical thermal threshold.

Adolescent↗
PubMed1979

[Results from the Central Laboratory for Streptococci Research in Kiel from 1965 to 1977 - a survey (author's transl)].

At the Central Laboratory for Streptococci Research at the Institute for Hygiene of the Federal Dairy Research Centre in Kiel a data bank has been established which comprises as well bibliographical data (until now more than 8000 titles out of the international literature concerning streptococci) as laboratory data of all strains which have been identified since 1965. For this present publication as a survey the total material covering 34,935 strains was analyzed and interpreted. Besides a short introduction describing the general examination procedure for streptococci and the encoding of results for the data bank the material is condensed in different tables considering the incidence of pathogenic species occuring mainly in man and animals. In addition findings of enterococci and lactic streptococci are presented. 41.8% of the strains examined were isolated from human specimens, 46.7% from cattle and the remaining ones from pigs, horses, dogs, laboratory animals and others. Only 2.0% of all cultures could not be identified as one of the known species. Remarkable observations are - the high incidence of group B-Streptococci in man - the unexpected frequency of typical "human" streptococci as those of group F and G and also Sc. milleri and Sc. MG in different animals - the possible interrelation of group L- and P-streptococci in pigs and cattle - the overlap of Sc. faecalis and Sc. faecium in man and animals showing no typical distribution as it is postulated in the literature - the high percentage of unidentifiable streptococci from pigs and laboratory animals as an eventual indication for some new species. In consecuting papers some problems emerging from the presented material and own experiments will be discussed as - interrelation of group B-Streptococci in man and cattle - incidence and importance of enterococci in humans, animals and foodstuffs and - classification of species not to identify by serological grouping.

Animals↗
PubMed1977

Mandibular reconstruction.

The stainless steel 316 mesh tray with cancellous bone offers a method of mandibular reconstruction which theoretically is appealing from the viewpoint of basic osseous healing. The results in fity-two patients at twenty different institutions indicates encouraging results. Further evaluation of this method is recommended.

Adolescent↗
PubMed1977

Lymphocyte activation by streptococcal antigens in psoriasis.

Cell-mediated immune responses in 28 hospitalized patients with psoriasis and in 36 healthy controls were studied using the two-step leukocyte migration agarose test. Specific cell-mediated immunity to A-streptococcal cell wall and cell membrane antigens occurred significantly more often in patients with psoriasis than in the control group. A statistically significant correlation between psoriasis-associated antigens of the HLA-B locus and cellular immune reactivity to A-streptococcal antigens or clinical course was not found. When patients with guttate psoriasis were compared separately with the control group, leukocyte migration inhibition induced by cell-free supernatants of A-streptococcal antigen-exposed mononuclear cell cultures was found to be more frequent than in other forms of psoriasis.

Adolescent↗
PubMed1976

Identification of streptococcal groups A,B,C, and G by slide co-agglutination of antibody-sensitized protein A-containing staphylococci.

A total of 98.7% of streptococci, groups A,B,C, and G, isolated from various sources was correctly identified by the co-agglutination technique. The active components in this technique are protein A-containing staphylococci coated with antibodies specific for group A,B,C, and G streptococci. A suspension of streptococci belonging to one of these four groups co-agglutinates with the antibody-sensitized staphylococci specific for this group. The technique is extremely rapid and simple and requires no special equipment. It should therefore be a valuable alternative to other techniques used in the grouping of streptococci and is shown here to be as reliable as the Lancefield technique.

Agglutination Tests↗
PubMed1976

[Comparative studies of dental plawue in students with and without dental caries. I. Enzymatic determination of the capacity to synthesize lactic acid in an aerobic medium].

In cultures of dental plaque taken from healthy dental surfaces of children susceptible to caries and children free from caries, the lactic acid content was determined. The cultures had an initial germ count of between 10(3) and 10(4) organisms per ml. After the cultures had been kept in artifical saliva for 7 hours under aerobic conditions, the samples of caries-susceptible children showed a considerably higher acid content than those of caries-free children. In comparative tests carried out in plaque samples simultaneously taken from the same dentitions, the micro-organisms of the samples taken from carious dental surfaces produced more lactic acid under the above mentioned conditions than those of the plaque samples taken from healthy dental surfaces.

Adolescent↗
PubMed1976

Homograft and prosthetic aortic valve replacement: a comparative study.

Homograft aortic valve replacement was done in 103 patients and prosthetic aortic valve replacement in 106 between January 1962 and December 1973. Patients who received homograft and prosthetic valves were compared with respect to age, sex, preoperative functional impairment, infection, dyspnea, angina, hemodynamics, chest X-ray, electrocardiogram, associated operations, early and late mortality, and valve failure. Combined total mortality was 28% (12% operative, 8% first postoperative year, 8% late). Ten percent of valve required replacement. One year after operation, 70% of survivors were asymptomatic, 27% were improved, and 3% were unchanged or between homograft and prosthetic valve replacement. Valve-related failure and infections were more common after homograft aortic valve replacement. Emboli, hemorrhage, and hemolysis were commoner after prosthetic valve replacement. Fungal infections occurred in five homograft patients but in no patient with a prosthetic aortic valve. Severe properative symptoms or recent endocarditis was associated with greater mortality and valve failure in both the homograft and the prosthetic series. Increased mortality and failure was also seen in patients with either preoperative aortic regurgitation with high left ventricular end-diastolic pressure and low cardiac index, or aortic stenosis with cardiomegaly or roentgenographic evidence of congestive heart failure. Therefore, in two series of patients at equal risk, mortality and valve failure were similar for homograft and prosthetic aortic valve replacement.

Adolescent↗