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Biomedical subjects

M Dieckmann

Publications and source records attributed to M Dieckmann.

13 recordsLinked to original sources
PubMed1998

Protein size resolution in human eye lenses by dynamic light scattering after in vivo measurements.

Dynamic light scattering (DLS) measurements were conducted with lowest intensity levels on human eye lenses (3.2 mW/cm2) within measurement times of 3-5 s. A characterisation of the human eye under in-vivo conditions along the optical axis is given and a careful interpretation of the data is made, referring not only to in-vitro results of investigated solutions of lens chemistry and various crystallin fractions but also to measurements performed on intact human lenses under various scattering angles. The clinical study was expanded to 79 subjects with ages varying from 9 to 85 years with no serious diseases of the ocular lenses. A normalisation of Scheimpflug photography density data to the data obtained by DLS enables comparison of the two techniques and shows good agreement. The bimodal character of the viscoelastic properties of healthy eye lenses was confirmed; with an assumed viscosity of 2 cP, the mean size parameter of the smaller component is 5.13 +/- 1.6 nm and of the polymeric fraction 690 nm.

Adolescent↗
PubMed1993

[The occurrence and significance of enterotoxin-producing Clostridium perfringens strains in the intestinal tract of horses].

100 faecal samples from clinically healthy horses of different age groups and feeding habits, 50 samples of faeces from horses suffering from enteropathy accompanied by diarrhoea and small and/or large intestine from 25 horses that had died after an intestinal disease were examined for the presence of Clostridium (Cl.) perfringens. The frequency with which Cl. perfringens was detected was 22% in clinically healthy horses, 32% in horses with diarrhoea and 52% in the dead horses. In two faecal samples from the horses with diarrhoea the microbial count of Cl. perfringens was ca. 10(6) cfu/g faeces. The occurrence of Cl. perfringens in clinically healthy horses was not influenced by age. In animals fed exclusively on grass silage Cl. perfringens was found more frequently. The enterotoxin of Cl. perfringens was identified in one of 36 faecal samples from horses with diarrhoea. 54 Cl. perfringens strains isolated from material examined were studied for their ability to sporulate and to produce enterotoxin. 98% of the strains formed spores. Enterotoxin production was negative in all cases. Experimental investigations with enterotoxin producing Cl. perfringens strains on four ponies did not show any signs of a possible durable colonization of the intestinal tract by this organism. The results of these investigations do not suggest any pathogenic relevance of enterotoxin producing Cl. perfringens strains to the development of enteropathy in horses.

Animals↗
PubMed1991

[Stomach ulcers in the horse--clinical and gastroscopic findings in 12 horses (1989-1990)].

Twelve horses with clinical symptoms of a gastric disorder were studied by gastroscopy. Symptoms of gastric disorders were periprandial colic, bruxism, ructus and reflux. Preliminary to gastroscopy the horses were fasted for 24 h. Access to water was not restricted. The gastroscopy could be conducted easily using a fiberscope 2.5 m in length and 11 mm in outer diameter. While ulcers were present in the squamous fundus of all horses only one horse showed ulceration of the glandular fundus. Solitary ulcers near the margo plicatus were found in horses with mild clinical symptoms. In contrast, diffuse gastroesophageal ulceration was accompanied by severe clinical symptoms. Four horses were affected by an acute gastroesophageal ulceration with gastric reflux and subsequent aspiration pneumonia. Two of those horses suffered from acute gastric ulceration 3-4 days following laparatomy. All horses were treated with cimetidine (5 mg/kg bwt/q.i.d.) until clinical symptoms ceased.

Animals↗
PubMed1990

Transduction of cellular neo mRNA by retrovirus-mediated recombination.

Transduction of cellular oncogenes by retroviruses is thought to be a multistep process, involving transcriptional activation of a cellular gene by upstream proviral integration and joining of cellular DNA to retroviral transcriptional signals, followed by copackaging and recombination with a helper virus genome during reverse transcription. To examine the molecular mechanism of the reverse transcriptase-mediated recombination, we introduced into mouse fibroblast cells a variety of constructs in which the neo selectable marker was joined to flanking retroviruslike or cell-like sequences. After superinfection and copackaging with a replication-competent Mo-MuLVsupF virus, the formation of recombinant neo transducing viruses was assessed in a second round of virus infection by the ability to confer G418 resistance to infected cells. Our results showed that recombinant neo proviruses were generated from neo RNA containing either a 5' or 3' retroviral end, implying that one recombination event with helper virus RNA was sufficient to incorporate the neo gene into proviral DNA. Recombination occurred with an apparent frequency of 10(-4) to 10(-5) per replication cycle in the absence of homology between the two recombining partners. This frequency, however, increased at least 100-fold if homology was provided at the site of recombination. Our results support the hypothesis that neo-transducing viruses arise via reverse transcriptase-mediated recombination of RNA rather than by recombination proceeding through DNA intermediates. Unexpectedly, removal of the retroviral packaging site psi reduced the number of neo recombinants only slightly. Our data indicated that although RNAs lacking the psi site are poorly packaged into virions, those RNAs that are included in the virions undergo frequent recombination, even if there is no selection for recombination. Many of the neo recombinants formed with the psi- constructs had undergone additional recombinations and often incorporated the psi site from the helper RNA.

DNA, Viral↗
PubMed1990

[Fallot's tetralogy in a calf--a case report].

A report is given on a calf with tetralogy of Fallot. This is the most common cyanotic congenital heart lesion in calves. Diagnosis was made by two-dimensional echocardiography and heart catheterisation. Tetralogy of Fallot was confirmed by necropsy.

Animals↗
PubMed1988

[Pregnancy during cyclosporin medication following a kidney transplant].

A 33-year-old patient became pregnant two years after transplantation of a cadaver kidney and continuous cyclosporine administration. An uncomplicated spontaneous delivery of a healthy boy weighing 3360 g took place in the 40th week. Cyclosporine was demonstrated in umbilical cord and neonatal blood and in the mother's milk, but not in amniotic fluid. Because mother's milk contained one sixth the concentration of cyclosporine in maternal blood, the mother was dissuaded from breast feeding.

Adult↗
PubMed1981

Cimetidine plasma concentration-response relationships.

Cimetidine plasma concentration-response relationships were investigated in six healthy subjects using suppression of gastric acid secretion under continuous pentagastrin stimulation (1.5 micrograms/kg/hr) as a test model. With the Hill equation the sigmoid was preferable to the linear relationship between plasma concentration and effect, and there were significant correlations of 0.78 micrograms/ml (range 0.54 to 1.04 micrograms/ml) for 50% inhibition of gastric acid secretion was determined; mean concentration for 90% inhibition was calculated to be 3.9 micrograms/ml. The model described should allow determination of whether different patient populations (e.g., healthy subjects, patients with ulcers, male and female patients, patients with renal or liver disease) differ from one another in concentration-response relationships to histamine H2-receptor antagonists, so that appropriate drug plasma levels should be achieved for specific degrees of inhibition of gastric acid secretion.

Adult↗
PubMed1975

Electron microscope localization of a protein bound near the origin of simian virus 40 DNA replication.

A salt-stable complex of protein and viral DNA obtained from Simian virus 40 (SV40)-infected monkey cells or mature SV40 virions has a novel structure. When viewed by high resolution electron microscopy, the circular SV40 DNA molecule has bound to it one to three globular protein "knobs". Using ecoRI and hpaII restriction endonucleases, each of which can cleave SV40 DNA once at a known location (10, 11, 12, 14), the bound protein can be localized at 0.7 plus or minis 0.05 on the SV40 DNA physical map (SV40 fractional length, clockwise from the ecoRI endonuclease-cleavage site).

Animals↗