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Biomedical subjects

H Hahn

Publications and source records attributed to H Hahn.

At least 163 records · Page 9Linked to original sources
PubMed1990

[Radiologic findings and differential diagnosis of bronchial asthma in childhood].

In children with asthma, routine chest X-ray typically shows bilaterally increased air volume, low diaphragms, wide diaphragmatic angles, and often a slender cardiac silhouette with a prominent pulmonic arch. Such an X-ray is not diagnostic of asthma itself, however, but rather of its complications: pneumonitis (particularly in toddlers with infectious asthma), atelectasis due to mucus obstruction, and, rarely, extra-alveolar air trapping (pneumomediastinum with or without cutaneous emphysema more often than pneumothorax). The differential diagnosis has to rule out "pseudo asthma" due to cystic fibrosis, alveolitis, achalasia, and foreign body aspiration.

Adolescent↗
PubMed1989

Acquired resistance to Listeria monocytogenes is mediated by Lyt-2+ T cells independently of the influx of monocytes into granulomatous lesions.

Facultative intracellular bacteria induce specific T cell responses of both the CD4+ and the CD8+ subsets. The immunohistological study of the tissue responses to Listeria monocytogenes in T cell subset-depleted, Listeria-primed mice revealed that CD4+ cells not only represent the predominant lymphocyte population in granulomatous lesions but mediate the attraction and accumulation of blood-borne monocytes into inflammatory foci. On the other hand, CD8+ T cells are able to mediate protection in the absence of CD4+ T cells, invading monocytes, and granulomatous inflammation, and therefore appear to activate resident macrophages for listericidal activity.

Animals↗
PubMed1989

[Quantitative assessment of heliotherapy in psoriasis vulgaris in high altitude climate].

At the Davos Clinic for Dermatology and Allergy (Alexanderhausklinik), patients suffering from psoriasis were treated with natural UV irradiation over 6 weeks in 1987: the average doses applied amounted to 1.042 J/cm2 UVB (= 41.7 sunburn units (SU] and 41.511 J/cm2 UVA. These doses were far below those of artificial UV sources usually required in the treatment of psoriasis. The doses were also far below those which statistically increase the incidence of non-melanotic skin cancer.

Altitude↗
PubMed1989

Determinants of invasion and survival of Yersinia enterocolitica in intestinal tissue. An in vivo study.

The invasion of intestinal tissue by Yersinia enterocolitica was studied after infection of mice with plasmid-bearing or with plasmidless strains of serotype 08 and 03. Within the first 15 h of infection each strain colonized the mouse ileum to the same extent, indicating that the initial binding and invasion are not plasmid dependent. This conclusion is supported by the finding that the plasmidless and the plasmid-bearing Yersiniae (serotype 08) colonize the ileum in a quantitatively similar, dose-dependent manner. The data show that the virulence of Yersiniae depends primarily on their ability to survive and to proliferate within the tissue. This character was expressed by the plasmid-bearing 08 strain, but not by the plasmidless 08 and 03 strain nor by the plasmid-bearing 03 strain. An orally induced rabbit antiserum was used to identify plasmid-coded antigens (relative molecular masses = 47, 45 and 42 kDa), which are expressed in vivo by the plasmid-bearing 08 strain, but not by the three other strains investigated. These antigens may be crucial for virulence of the 08 strain.

Animals↗
PubMed1989

[In-vitro activity of enoxacin: a multicenter study].

The in vitro activity of enoxacin was tested in 14 German microbiological centers shortly after the introduction of the drug in Germany. 2748 unselected clinical isolates including 15 bacterial species were analysed using microtiter plates. The MIC90-values were as follows: Staphylococcus aureus 4 mg/l, Enterococcus faecalis 16 mg/l, Enterobacteriaceae 0.5 mg/l, Pseudomonas aeruginosa 8 mg/l. There is good correlation between these results and those of former investigations. It is known that quinolones are only moderately active against enterococci. 8.5% of S. aureus, and 1.4% of Enterobacteriaceae were found to be resistant (MIC greater than 4 mg/l). As to P. aeruginosa, the study revealed that despite a generally low rate of resistance in specific clinical settings, specific problems can arise: in one institution, the MIC90 of P. aeruginosa was 32 mg/l, with a resistance rate of 56.1% (n = 57). In the other centers the MIC90 was 2 mg/l and the resistance rate 5.0% (n = 302). In the first center, many of the isolates were from paraplegic patients or patients with cystic fibrosis pretreated with quinolones. This study will be repeated in two years' time in order to determine an eventual change in resistance.

Bacteria↗
PubMed1989

Synergism between ciprofloxacin and fosfomycin against gram-negative bacteria in vitro.

A combination of ciprofloxacin and fosfomycin was evaluated for synergism employing time-kill experiments. A total of 59 clinical isolates of gram-negative bacteria was examined. All organisms were moderately sensitive or resistant to ciprofloxacin; 72.9% also showed moderate sensitivity or resistance to fosfomycin. After 24 h, synergism was seen in 22% of the strains, i.e. less than reported by other authors. There was no correlation between synergistic action and sensitivity to ciprofloxacin and fosfomycin, respectively.

Ciprofloxacin↗
PubMed1989

The minimum inhibitory concentrations of various bismuth salts against Campylobacter pylori.

The minimum inhibitory concentrations of five bismuth salts (bismuth subcitrate, bismuth subgallate, bismuth subnitrate, bismuth subsalicylate and tripotassium dicitrato bismuthate, a water soluble compound of bismuth subcitrate) were assayed against 48 strains of Campylobacter pylori employing the agar dilution method. Tripotassium dicitrato bismuthate was most effective (MIC50 8 mg/l), the other bismuth salts exhibited somewhat lower inhibitory activities. It is concluded that bismuth salts are suitable agents for inhibiting growth of Campylobacter pylori.

Antacids↗
PubMed1989

Induction of SOS repair by monofunctional methanesulphonates in various Escherichia coli strains. Structure-activity relationships in comparison with mutagenicity in Salmonella typhimurium.

Seventeen monofunctional alkylmethanesulphonates of widely varying structures were investigated in the SOS Chromotest using the Escherichia coli strains PM21, PQ37 and GC4798. As a measure of the SOS-inducing activity, the beta-galactosidase enzyme units (Up/mumol) were determined. Strains PM21 and PQ37 gave similar results in spite of the presence of different genetic markers. In general, the SN1 type secondary compounds (O-alkylation) induced higher SOS repair than the SN2 type primary compounds (N-alkylation). However, methylmethanesulphonate exerted the highest SOS induction of all tested strains, presumably due to its extremely high SN2 reactivity. In general, strain GC4798, which lacks 3-alkyladenine-DNA glycosylases I and II, was more sensitive towards monofunctional alkylating compounds and in particular towards the SN2 type compounds. A good correlation was found between the SOS repair response in the E. coli strains PM21 and PQ37 and the mutagenicity in Salmonella typhimurium TA100. There was, however, little correspondence when comparing the two measures used for the SOS-inducing activity in this work, the SOSIP (SOS-inducing potency) and the specific beta-galactosidase activity (Up/mumol). This effect was explained by the different toxicity corrections used for the calculation of the two measures. Whereas for the SOSIP value the single constitutive enzyme alkaline phosphatase is used, for the Up/mumol the absorbance at 600 nm, which indicates the growth delay (overall toxicity), is utilized. The influence of the toxicity corrections is discussed in more detail.

Alkylating Agents↗
PubMed1989

Contact allergy due to colophony (III). Sensitizing potency of resin acids and some related products.

7 resin acids, 3 synthetically prepared derivatives and the neutral fraction of Chinese colophony were studied by experimental sensitization using a modified FCA method. 4 resin acids, laevopimaric, abietic, podocarpic and tetrahydroabietic, proved to be weak sensitizers. Neoabietic, dehydroabietic, isopimaric acid and larixol remained negative. However, the derivatives, methyl abietate and calcium abietate, were shown to be moderate sensitizers, and the maleic-modified adduct to be a moderate to strong sensitizer. As laevopimaric acid plays only a minor rôle in colophony, abietic acid must be considered a major, even if weak, allergen in non-modified colophony. The neutral fraction of colophony is also partially involved in colophony allergy.

Animals↗
PubMed1989

Immunohistochemical and electron microscopic study of interaction of Yersinia enterocolitica serotype O8 with intestinal mucosa during experimental enteritis.

The experimental infection of mice with Yersinia enterocolitica serotype O8 was investigated in a quantitative and histological study. The course of bacterial penetration and spreading was precisely determined by immunohistochemical staining. After oral administration, the bacteria passed the epithelial barrier of the ileum and spread into the lamina propria. By preference they entered Peyer's patches, which were about 1,000 times more heavily colonized than the surrounding epithelium of a comparable surface area. The bacteria proliferated in the follicles, from which they spread into the lamina propria of the villi. At either site most of the bacteria multiplied extracellularly, with only a small percentage observed to be present within the phagocytes. The bacteria did not appear to be able to pass the intact basement membrane; hence, the integrity of the basement membrane is likely to play a role in determining the route of entry and limit of spread of Y. enterocolitica infection.

Animals↗
PubMed1988

Comparative efficacy of ciprofloxacin, ceftazidime and gentamicin, given alone or in combination, in a model of experimental septicemia due to Klebsiella pneumoniae in neutropenic mice.

The therapeutic efficacy of ciprofloxacin, used alone and in combination with either ceftazidime or gentamicin, was evaluated in a model of experimental Klebsiella pneumoniae septicemia in neutropenic mice. Therapeutic results were compared to those achieved by treatment with ceftazidime or gentamicin alone, as well as their combination. Infections were induced by i.v. injection of two strains of K. pneumoniae. Therapy with i.m. antibiotics was performed in 8 h intervals for a total of 13 doses, and survival rates were recorded at the end of treatment as well as seven days later. Ciprofloxacin alone proved to be significantly more effective than ceftazidime and gentamicin, producing survival rates similar to the combination of ceftazidime plus gentamicin. Bacterial counts of spleens and blood confirmed the superior bactericidal activity of ciprofloxacin. Except for the combination of ciprofloxacin with ceftazidime, there was no apparent advantage of combinations of ciprofloxacin with the other agents compared to ciprofloxacin alone. These data suggest a high in vivo activity of ciprofloxacin in systemic infection due to K. pneumoniae.

Agranulocytosis↗
PubMed1988

The influence of ciprofloxacin treatment in vivo on cell-mediated immunity to Listeria monocytogenes.

The intravenous and intraperitoneal administration of ciprofloxacin in very high doses (2 x 1 mg/d up to 2 x 2 mg/d) can reduce the bacterial load of mice experimentally infected with the intracellular bacterium, Listeria monocytogenes. The T-cell response generated during the treated infection is affected in much the same way as it is during antibiotic treatment with ampicillin, i.e. the protective immunity established directly correlates with the number of bacteria present during an extended period of time during the primary infection. Although an additional anti-proliferative effect of ciprofloxacin on expanding T-cells as evidenced in in vitro experiments cannot be excluded, our data in summary favour the view that in vivo this effect is at most of minor importance.

Ampicillin↗