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Biomedical subjects

K Wilke

Publications and source records attributed to K Wilke.

At least 37 records · Page 2Linked to original sources
PubMed1993

[Bacterial reducing qualities of copper-containing and non-copper-containing materials. I. Contamination and sedimentation in humid and dry conditions].

In this examination the bactericide qualities of different materials were tested. Particularly the effect of humidity was examined. 3 materials containing copper ("copper", "brass" and "brass sheet") and 2 materials not containing copper ("polyamide B" and "high-grade steel") were tested. The surfaces of the 5 types of material were contaminated with a suspension of 2 different bacteria species (Staphylococcus aureus and Micrococcus luteus). After defined exposure times the survival rate of the microorganisms on the surfaces was determined by the standardized method of the "Guidelines of the German Society of Hygiene and Microbiology". Additionally the sedimentation of airborne microorganisms on the materials was tested by determining the number of colony-forming-units after defined exposure times. In further examinations the materials were contaminated by hands, which were dipped into a suspension of different microorganisms (Micrococcus luteus, Staphylococcus aureus, Enterococcus faecium, Escherichia coli, Enterobacter cloacae and Pseudomonas aeruginosa). The following ways of contaminating the test materials were chosen: single contamination with wet hands, repeated contamination with wet and dry hands. After defined exposure times the survival rate of the microorganisms on the surfaces was determined. The results show, a bactericide quality of copper depends on the percent of copper-content of the tested materials, exposure time, humidity, frequency of contamination and bacteria species. Humidity and only single contamination cause a reduction of bacteria. Reduction of gram-negative bacteria is more easily than reduction of gram-positive bacteria. Enterococcus faecium shows the highest, Pseudomonas aeruginosa the lowest reduction rate of bacteria in the following sequence: Enterococcus faecium, Escherichia coli, Enterobacter cloacae, Micrococcus luteus, Staphylococcus aureus and Pseudomonas aeruginosa.

Air Microbiology↗
PubMed1992

Transplantation of embryonic retina to the subretinal space in rabbits.

Embryonic rabbit retina can be transplanted to the subretinal space of adult rabbit with a new method, which gives a high rate of successful short-term transplants. Embryonic (stage E 15) neural retina cells were injected through an incision just behind the sclerocorneal border with a thin (inner diameter 0.15-0.4 mm, outer diameter 0.3-0.5 mm) plastic tube attached to a specially designed instrument, by which the length of the protruding plastic tip could be controlled. The retina was penetrated from the vitreous side and the donor tissue was injected into the subretinal space. The cells survived in the host for at least 5 months, although the long-term survival rate tended to decrease. The transplanted cells matured and differentiated, forming an approximation of the layered, retinal structure with some anomalies (e.g. rosettes). The subretinal location offers an interesting and convenient way of studying the development of retinal cell transplants in rabbits. Large transplants can be produced, and the risk for failures due to erroneous vitreous placement is small.

Animals↗
PubMed1988

Sequential order of target-recognizing domains in multispecific DNA-methyltransferases.

In the multispecific DNA(cytosine-5)-methyltransferases (Mtases) of Bacillus subtilis phages SPR and phi 3T the domains responsible for recognition of DNA methylation targets CCA/TGG, CCGG, GGCC (SPR) and GCNGC, GGCC (phi 3T) represent contiguous sequences of approximately 50 amino acids each. These domains are tandemly arranged and do not overlap. They are part of a 'variable' segment within the enzymes which is flanked by 'conserved' amino acids, which are very similar amongst bacterial monospecific and the multispecific Mtases studied here. These results follow from a mutational analysis of the SPR and phi 3T Mtase genes. They further support our concept of a modular enzyme organization, according to which variability of type II Mtases with respect to target recognition is achieved by a combination of the same enzyme core with a variety of target-recognizing domains.

Amino Acid Sequence↗
PubMed1987

Construction and use of chimeric SPR/phi 3T DNA methyltransferases in the definition of sequence recognizing enzyme regions.

Multispecific DNA methyltransferases (Mtases) of temperate Bacillus subtilis phages SPR and phi 3T methylate the internal cytosine of the sequence GGCC. They differ in their capacity to methylate additional sequences. These are CCGG and CC(A/T)GG in SPR and GCNGC in phi 3T. Introducing unique restriction sites at equivalent locations within the two genes facilitated the construction of chimeric genes. These expressed Mtase activity at a level comparable to that of the parental genes. The methylation specificity of chimeric enzymes was correlated with the location of chimeric fusions. This analysis, which also included the use of mutant genes, showed that domains involved in the recognition of target sequences unique to each enzyme [CCGG, CC(A/T)GG or GCNGC] are represented by the central non-conserved parts of the proteins, whilst recognition of the sequence (GGCC), which is a target for both enzymes, is determined by an adjacent conserved region.

Bacillus subtilis↗
PubMed1986

Indications of trabeculectomy in open angle glaucoma.

The indications and frequency of trabeculectomy operations in Swedish eye clinics in 1980 and 1981 were assessed. The incidence of operations are significantly higher in the north than in the south of the country. The geographical influence was eliminated by excluding the 6 northernmost clinics, but the frequency of operations still varied with a factor of nearly 5 between the clinics. Most clinics seemed to allow individual modifications and exceptions to the rules of indication for surgery. An IOP surpassing a certain limit, locally fixed but varying greatly between clinics, was an indication in most places, even if the visual field was normal. An optic disc defect alone was an indication for surgery in one clinic only. In most clinics a progression of the glaucoma visual field defect with or without disc damage was an indication of surgical intervention.

Glaucoma, Open-Angle↗
PubMed1983

Histopathology in botryomycosis-like panophthalmitis due to Staphylococcus aureus. A light microscopic and electron microscopic study. A case report.

A Swedish farmer's wife aged 46 developed a unilateral panophthalmitis 6 weeks after a visit to Gambia in Africa. Vitreous puncture revealed growth of Staphylococcus aureus, but in spite of adequate treatment the eye had to be enucleated 5 weeks after the onset of symptoms. Gram-positive microorganisms in botryomycosis-like granules in the vitreal abscesses were at first suspected to be Histoplasma capsulatum. Electron microscopic examination revealed microorganisms, consistent with staphylococci. There was extensive proliferation of mesosomes, most probably due to the intense treatment. The poor nutrition and slow resorption of the dead microorganisms from the avascular vitreous did possibly also play a part in the proliferation of the mesosomes.

Anti-Bacterial Agents↗
PubMed1978

Topical atenolol versus pilocarpine: a double-blind study of the effect on ocular tension.

Topical atenolol (a beta1-adrenoceptive antagonist), pilocarpine, and placebo were tested in a randomised double-blind crossover trial of 8 patients with ocular hypertenion. Atenolol (2% 3 times a day) caused a fall in intraocular pressure (IOP) comparable to that achieved by topical application of pilocarpine (2% 3 times a day). The decrease in IOP by each compound was demonstrable on the second day of application and was significantly (P is less than 0.05) reduced on the seventh and 14th days of treatment. The combination of 2% pilocarpine and 2% atenolol administered 15 minutes apart (3 times a day) lowered the IOP significantly from the second day of treatment, and this reduction persisted throughout the trial period of 14 days. This combined of treatment, treatment lowered the IOP more than either substance alone. However, this further decrease was statistically significant only on the 14th day of treatment (atenolol versus atenolol + pilocarpine, P is less than 0.05). No change of the episcleral venous pressure was observed after 14 days' treatment with either atenolol or pilocarpine alone, or combined.

Adult↗