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Biomedical subjects

G Gassner

Publications and source records attributed to G Gassner.

8 recordsLinked to original sources
PubMed1998

[Observations on the side effects after application of non-steroidal anti-inflammatory agents in dogs].

This review describes with some examples possible side-effects after oral treatment with the non-steroidal anti-inflammatory drug meloxicam in dogs. Adverse effects include gastrointestinal and renal irritation such as nausea, vomiting and hemorrhagic gastroenteropathy. Therefore in case of long-term administration a dose reduction of 50 percent (single dose of 0.2 mg/kg followed by 0.1 mg/kg once daily) is recommended in dogs with chronic locomotor disorders.

Animals↗
PubMed1994

Reaction of phthalate dioxygenase reductase with NADH and NAD: kinetic and spectral characterization of intermediates.

Phthalate dioxygenase reductase (PDR) is an electron transferase that contains FMN, which accepts a hydride from NADH, and a [2Fe-2S] center, which transfers electrons to phthalate dioxygenase. The reduction of PDR by NADH has been studied by stopped-flow spectroscopy. Data from studies using both portio- and deuterio-NADH were analyzed by nonlinear curve fitting and numerical simulation techniques. The results of these analyses indicate that the reductive half-reaction of PDR consists of five distinct kinetic phases: (a) NADH binds to form a primary Michaelis complex (MC-1) (Kd = 50 microM). (b) The enzyme undergoes a structural change (116 +/- 5 s-1) resulting in a charge-transfer complex (CT-1). (c) The next phase in the reaction shows a deuterium isotope effect of 7.0 when (4R)-[2H]NADH (NADD) is substituted for NADH, identifying this step as the one involving hydride transfer. The rate of hydride transfer from NADH to FMN is 70 s-1, and this process results in a charge-transfer intermediate between the flavin hydroquinone anion and NAD (CT). (d) Internal electron transfer from the flavin to the iron-sulfur center, which is only 35 +/- 4 s-1, then results in an intermediate consisting of a reduced [2Fe-2S] center and a neutral flavin semiquinone (SQ). It is surprising that this rate is so slow, since the shortest interatomic distance between these centers is only 4.7 A [Correll, C. C., et al. (1992) Science 258, 1604-1610]. The 2-electron-reduced form of PDR (SQ in Figure 1) binds weakly to the reaction product, NAD (Kd = 3.7 mM), but forms a tight complex with NADH (Kd = 10 microM). (e) Two molecules of the reduced iron-sulfur flavin semiquinone (SQ) form of PDR then undergo a relatively slow second-order disproportionation reaction, resulting in one molecule of 3-electron-reduced PDR and one molecule of 1-electron-reduced PDR. The latter reacts rapidly with excess NADH to form a 3-electron-reduced PDR.

Burkholderia cepacia↗
PubMed1987

Combined proton NMR imaging and spectral analysis of locust embryonic development.

Images and spectra of desert locust [Schistocerca gregaria (Forskal)] embryos were collected in vivo using a 4.7-tesla proton ((1)H) NMR imaging spectrometer. The 100 x 100 x 500 mum image resolution and 125-nl localized spectral volumes were obtained within minutes of each other. The dynamics of embryonic development were slow enough that the time delay between imaging and spectral measurements is negligible. Thus, image and spectral data correspond closely and approximate real-time observations of embryonic changes. The above procedure was applied every 12 hr during the entire course of development. This analytical approach demonstrates that imaging and localized spectroscopy can be used to visualize and assess changes in embryonic water and lipid content in concert with the development of a living embryo.

Journal Article↗
PubMed1986

Modification of N-methyl-N-nitrosourea-induced urinary bladder carcinogenesis in rats following stimulation of urothelial proliferation by a partial cystectomy.

The present experiments are concerned with the question whether stimulation of urothelial proliferation modifies tumor development in the urinary bladder. To induce proliferative activity of the urothelium a partial cystectomy (one-third resection of the bladder) was performed in female Wistar rats. N-Methyl-N-nitrosourea (MNU) was used as a carcinogen which acts directly on the urothelium without requiring metabolic activation. MNU was given as a single intravesicular dose of 5 mg/kg body weight via a urethral catheter. After an experimental period of 15 months rats with an intact quiescent bladder showed a tumor incidence of 32.6%. Rats having received MNU 45 h following partial cystectomy - when proliferative activity reached its peak - had developed bladder tumors with a frequency of 17.9%. Initial administration of MNU followed 24 h later by a one-third resection of the bladder resulted in a tumor incidence of only 8.8%. The histologic types of tumors induced proved to be similar to those found with other carcinogens. However, by contrast the majority of urothelial tumors were characterized by a squamous metaplasia. There was no substantial difference between the various histologic tumor types found in the resting and regenerating bladder. The mechanisms responsible for the observed inhibition of tumor development in the regenerating bladder are unknown. It is assumed that an increased capacity of the proliferating urothelial cells to repair carcinogen-induced DNA damage may play an important role.

Animals↗
PubMedDate not supplied

[Chronic thallium intoxication in five German pointers of one litter].

The difficulty of diagnosis and therapy of chronic thallium intoxication is described in five German Pointers with the same skin disease. The detection of thallium in cases of skin lesions like the cutaneous erythema with oedema and crusts or in chronic cases with multifocal alopecia is difficult. The first diagnostic information was gathered in this case from the high thallium level in the urine. The thallium concentration in the hair is subject to great variations, even in physiologic conditions. The trichogramme showed in this case pathognomonic changes like adhesion of the hair follicles. Differential diagnosis for this symmetric alopezia without pruritus are hormonal disturbances or, in puppies, the generalized form of demodicosis. The five affected dogs were treated with Fe III-Hexacyanoferrat. The clinical appearance of the skin improved slowly during a period of 1-2 months.

Animals↗