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Biomedical subjects

M Maywald

Publications and source records attributed to M Maywald.

6 recordsLinked to original sources
PubMed1998

In vitro studies of ferritin iron release and neurotoxicity.

The increase in brain iron associated with several neurodegenerative diseases may lead to an increased production of free radicals via the Fenton reaction. Intracellular iron is usually tightly regulated, being bound by ferritin in an insoluble ferrihydrite core. The neurotoxin 6-hydroxydopamine (6-OHDA) releases iron from the ferritin core by reducing it to the ferrous form. Iron release induced by 6-OHDA and structurally related compounds and two other dopaminergic neurotoxins, 1-methyl-4-phenylpyridinium iodide (MPP+) and 1-trichloromethyl-1,2,3,4-tetrahydro-beta-carboline (TaClo), were compared, to identify the structural characteristics important for such release. 1,2,4-Trihydroxybenzene (THB) was most effective in releasing ferritin-bound iron, followed by 6-OHDA, dopamine, catechol, and hydroquinone. Resorcinol, MPP , and TaClo were ineffective. The ability to release iron was associated with a low oxidation potential. It is proposed that a low oxidation potential and an ortho-dihydroxyphenyl structure are important in the mechanism by which ferritin iron is mobilized. In the presence of ferritin, both 6-OHDA and THB strongly stimulated lipid peroxidation, an effect abolished by the addition of the iron chelator deferoxamine. These results suggest that ferritin iron release contributes to free radical-induced cell damage in vivo.

1-Methyl-4-phenylpyridinium↗
PubMed1987

[Etiology of corneal ulcers with special reference to bacterial genesis].

The authors report on 134 patients (141 eyes) seen between May 1982 and December 1985 with corneal ulcers with or without hypopyon. Eight patients (11 eyes) had a facial palsy, 7 (7 eyes) a varicella zoster infection, 1 (2 eyes) a marginal ulcer ("furrow keratitis") associated with collagenosis, 29 (29 eyes) an ulcerative keratitis with endophthalmitis, 1 (2 eyes) a pemphigoid-associated ulcer and 90 (92 eyes) a herpetic infection. Pathogenic bacterial strains were isolated from 20 patients: 10 coagulase-positive Staphylococcus aureus (4 coinfections), 3 Pseudomonas aeruginosa (1 coinfection), 2 Proteus mirabilis (1 coinfection), 2 Escherichia coli and Enterobacter cloacae, Citrobacter freundii and beta-hemolyzing streptococci as well as enterococci in one case each, and non-hemolyzing streptococci and alpha-hemolyzing streptococci in two cases each as coinfections. A comparison of the range of bacterial strains of postoperative endophthalmitis and kerato-/conjunctivitis with bacterial corneal ulcers revealed a high percentage of gram-negative organisms in the latter. Laboratory work-up should include microscopy, agar plating and differentiation as well as antibiotic sensitivity testing and modern immunofluorescent direct techniques. Management includes bactericidal topical and systemic antibiotic regimens as well as surgical procedures if necessary, e.g., perforating tectonic and mini-keratoplasty, and conjunctival flapping followed by lamellar keratoplasty.

Anti-Bacterial Agents↗
PubMed1987

[Ocular involvement in ectodermal dysplasia].

The authors describe the ophthalmological findings and clinical course in two patients with EEC syndrome and one patient with anhydrotic ectodermal dysplasia. A retinal complication was seen in a 43-year-old patient which seems to be associated with the EEC syndrome and has not yet been described. A review of the literature indicates the frequency of ocular findings. So far, primary ocular changes in anhydrotic ectodermal dysplasia have never been observed. The older the patient, the more severe the secondary complications affecting the lids and cornea can be; the eye may even be lost.

Adult↗
PubMed1981

Comparison of distribution of doxycycline in mice after oral and intravenous application measured by a high-performance liquid chromatographic method.

Doxycycline levels in various organs of mice after i.v. and p.o. administration were measured by a high-performance liquid chromatography method. When given as a single dose (50 mg/kg) i.v. doxycycline accumulated in the lung. High concentrations were also measured in liver and kidneys. When 50 mg/kg doxycycline were administered by stomach tube to fed mice the antibiotic accumulated to a lesser degree in the lung. On the other hand, the antibiotic levels in the liver and the kidneys were higher as after i.v. injection. The absorption of doxycycline administered p.o. was about 92% and seemed not to be influenced by food in the stomach. The elimination half-life in mice was 170 min independent of the route of administration.

Administration, Oral↗
PubMed1981

Comparative evaluation of the effects of tetracycline and doxycycline on blood and liver lipids on male and female mice.

The effects of tetracycline and doxycycline (10-100 mg/g i.v.) on the triglyceride and cholesterol contents of liver and blood were studied comparatively in male and female mice. Only tetracycline increased the triglyceride content of the liver. The cholesterol content of the liver was raised by both tetracycline and doxycycline. Tetracycline and doxycycline increased the concentration of unesterified cholesterol and decreased esterified and total cholesterol in the serum. Most effects were more consistent or more pronounced in females than in males.

Animals↗