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Biomedical subjects

M Wilms

Publications and source records attributed to M Wilms.

7 recordsLinked to original sources
PubMed2005

Natural course of autoimmune thyroiditis in type 1 diabetes: association with gender, age, diabetes duration, and puberty.

AIMS: To investigate the natural history and incidence of autoimmune thyroiditis (AIT) in paediatric patients with type 1 diabetes (T1D). METHODS: Since 1990, annual screening for thyroid disease has been performed in children and adolescents with T1D. Antibodies against thyroperoxidase (anti-TPO) and thyroglobulin (anti-TG) as well as TSH were measured in 659 patients (54.3% boys). In 126 patients, anti-TPO and anti-TG levels were followed at yearly intervals from onset up to five years of T1D. Anti-TPO above 30 U/ml and anti-TG above 20 U/ml were considered positive, values above 100 U/ml as significantly raised and indicative of AIT. L-thyroxine treatment was started if TSH was higher than 4.5 microU/ml and/or thyroid gland enlargement on thyroid ultrasound was present. RESULTS: At initial screening, 15.4% of patients had raised anti-TPO and 14.4% anti-TG. Girls had more frequently raised antibodies than boys. Sixty two patients (9.4%, 61% girls) required treatment with L-thyroxine. The cumulative incidence (SE) of AIT after 10 years of diabetes was 0.14 (0.02), being significantly higher in females (0.18 (0.03)), particularly after the age of 12 years. At T1D onset, positive anti-TPO and anti-TG were present in 21 of 126 patients (16.7%), each. All patients with significantly increased values of anti-TPO (n = 17, 148-5340 U/ml) and anti-TG (n = 11, 140-2000 U/ml) at T1D onset remained positive during the following five years. CONCLUSIONS: For early detection of autoimmune thyroiditis in children with T1D, measurement of anti-TPO and TSH at T1D onset and in yearly intervals after the age of 12 years is recommended.

Adolescent↗
PubMed2001

[Physiological functional evaluation of retinal implants in animal models].

Retinal implants can--by electrical stimulation--create visual impressions in people with certain kinds of degenerative retinal diseases (e.g. Retinitis Pigmentosa). Electrically evoked potentials in the retina must be transferred into the visual cortex in an orderly manner, a prerequisite for any kind of form- and movement-perception. In the current developmental stage the difficult investigations are performed in various animal models: isolated retinae of intact chicken and of RCS-rats (a model for Retinitis Pigmentosa), as well as in anesthetised rabbits, pigs and cats with intact retinae. Our investigations show that spatially selective ganglion-cell responses can be recorded following focal electrical stimulation, in healthy and as well in degenerated retinae. Registration of activities in area 17 of the visual cortex demonstrate that electrical retinal stimulation can indeed activate it.

Animals↗
PubMed2000

Implantation of retina stimulation electrodes and recording of electrical stimulation responses in the visual cortex of the cat.

BACKGROUND: Simple basic visual perception may be restored by epiretinal electrical stimulation in patients that are blind due to photoreceptor loss. To stimulate ganglion cells, epiretinally flat platinum microelectrodes embedded in thin polyimide film were developed and tested in the cat. METHODS: After removal of the lens and the vitreous body a thin microfilm electrode array was implanted through a corneoscleral incision in the cat eye (n = 4). In two eyes no further attempt was made to fixate the tip of the electrode, which was pressed onto the retinal surface due to the tension of the curved polyimide film. In two eyes the tip of the electrode was fixed with cyanoacrylate adhesive. The exterior part of the microelectrode film was directed under the skin towards the forehead which allowed fixation of the microplug to a head fixation bolt. Retinal stimulation experiments were performed within 1 week after implantation. Success of stimulation was assessed by recording neuronal activities from areas 17 and 18. Retinal microelectrodes were removed 2 weeks or longer after implantation. RESULTS: Intraocular inflammation or retinal detachment were not observed after implantation of the microelectrode film. In two eyes the tip of the microelectrodes dislocated spontaneously within the first few days. The lowest threshold of electrical stimulation was 35 microA, corresponding to a charge transfer of 14 nC per phase. These values were ten times higher than those obtained by needle electrodes used in prior experiments. CONCLUSIONS: Intraocular implanted flat microelectrodes made of platinum and polyimide were well tolerated. Because of the flat configuration of the microelectrodes higher stimulation thresholds than for needle electrodes were found, indicating insufficient contact to the retinal surface. An alternative shape and fixation technique is required to minimise electrodes' threshold of stimulation.

Animals↗
PubMed1980

[Pharmacokinetics of etomidate in man (author's transl)].

The pharmacokinetic behaviour of etomidate was investigated in 7 patients. A method for the analysis of etomidate is described using gas-liquid chromatography for separation and alkali flame ionization detection. The lower limit of detection for etomidate in plasma was 0.005 microgram/ml. The pharmacokinetic behaviour of etomidate after an intravenous bolus injection of 20 mg may be described in terms of an open two-compartment model. The plasma half-life of etomidate was in the alpha-phase about 3 minutes, the biological half-life of the beta-phase was about 70 minutes. The total volume of distribution was calculated at 165 litres. The total plasma clearance amounted to 1600 ml/min. These pharmacokinetic data were used to establish an intravenous infusion scheme for etomidate.

Aged↗
PubMed1980

[Infusion model for etomidate (author's transl)].

An intravenous infusion scheme was established in five healthy volunteers on the basis of pharmacokinetic analysis as described by J.G. Wagner. Concentrations of etomidate in plasma were measured by gas chromatography after solvent extraction. The monitoring of EEG background activity was used for the correlation to the pharmacodynamic effect. The minimal plasma level producing an hypnotic effect was about 0.3 microgram/ml) etomidate. An infusion model was developed for a therapeutic plasma concentration of 0.5 microgram/ml etomidate. An initial fast constant-rate infusion (8 mg/min) was followed by an infusion with 0.8 mg/min for the entire duration of the application. The measured plasma levels coincided fairly well with the predicted steady state plasma levels and were accompanied by a distinct hypnotic effect in all volunteers.

Adult↗
PubMed1975

Flash photometric experiments on the photochemical cycle of bacteriorhodopsin.

The photochemical reaction cycle of bacteriorhodopsin was investigated by means of flash photometric methods. Three different intermediates with absorption maxima at about 630 nm, 411 nm, and 646 nm could be detected. Kinetic data of the occurrence of these intermediates were obtained from isolated purple membrane in different mediums and from intact halobacteria. An activation energy of 14.1 +/- 0.4 kcal-mol-1 and of about 19 kcal-mol-1 for formation of bacteriorhodopsin 411 and of bacteriorhodopsin 565, resp., was calculated. pH-changes in the medium caused by the reaction cycle of bacteriorhodopsin were detected by use of the pH-indicator bromocresol green.

Bacteriorhodopsins↗