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Biomedical subjects

H Peil

Publications and source records attributed to H Peil.

7 recordsLinked to original sources
PubMed1990

Age-related retinal changes--comparison between albino and pigmented rats.

To characterize aging as a factor responsible for structural changes the retinae of 47 Wistar-derived albino rats and 50 pigmented rats of the Norway and BDE (Han) strains between the ages of 1 and maximal 36 month were examined by light and electronmicroscopy and analysed for changes in cell densities. In all 3 rat strains there was an overall decline in nuclear densities of outer layer nuclei by 38 - 50% and inner layer nuclei by 27 - 33% between the ages of 1 and 27 months. Over the same age-range the ganglion cell loss was comparable to the decline in the inner nuclear layer. Neuronal cell death occurred at all ages and was more pronounced in albino rats. Moreover, in albino rats, cones were more resistant than rods to destruction by age and ambient light. Age-related ultrastructural changes in the retinal pigment epithelial cells (RPE) were in both pigmented strains: (1) a substantial accumulation of lipofuscin, (2) an apparent thickening of the basement membrane and (3) absent or greatly enlarged pleomorphic basal infoldings. In up to 27-month old BDE (Han) and 36-month old Norway rats besides mature stage IV-melanosomes also stage III-melanosomes can be observed. Characteristic of RPE-cells in old rats of these two strains were also compound granules and compound melanosomes. In peripheral RPE-cells of albino rats premelanosomes can be sporadically detected up to 31 months of age. Age-related changes in retinal vessels were found in the superficial and deep capillary network. The only finding was a 2-3 fold increase in thickness of the capillary basement membrane.

Aging↗
PubMed1989

Sustained active ingredient release from drugs: statistical model for random sample assessment in vitro.

A method is presented according to which tolerances for active ingredient release from pharmaceutical dosage forms are calculated. The procedure is based on a statistical model. In accordance with this, the mean value is specified as a measure of the amount of active ingredient released, and the standard deviation as a measure of the uniformity of the active ingredient release. The determination of drug release tolerances is standardized. Based on clinically tested samples, changes arising from the manufacture and the storage are taken into account, thus establishing a manufacturing standard. Depending on the information available, a dynamic adaption of drug release tolerances (e.g., during the development phase) is recommended.

Delayed-Action Preparations↗
PubMed1986

A contribution to indirect ophthalmotonometry in beagles.

A test of suitability of the electroimpression tonometer from Fritz Schwarzer GmbH, Munich, for measuring intraocular pressure in dogs was performed. Intraocular pressure of 63 clinically healthy English beagles was measured in both eyes using the instrument with different plunger weights. Intraocular pressure and volume of corneal depression during measurement were determined as a function of the plunger weight from readings on the tonometer with the aid of Friedenwald's tables (2). Using Friedenwald's law and with knowledge of the rigidity coefficient, an intraocular pressure of 32.7 mmHg was found, with individual variations between 12.8 and 54.2 mmHg. The rigidity coefficient for dogs, which was determined by linear regression, was, on average, 0.0103. Differences between male and female dogs were not significant for either parameter. A conversion table for eyes with a rigidity factor of 0.0103 is attached. Intraocular pressure as a function of plunger weight and the reading of measurement is shown in mmHg. In our measurements the Schwarzer electrotonometer for determination of intraocular pressure provided easily reproducible readings.

Animals↗
PubMed1985

Pharmacokinetics of adimolol after single and multiple dose administration in healthy volunteers.

The pharmacokinetic properties of adimolol (MEN 935), a new antihypertensive agents with predominantly beta-receptor blocking and additional alpha-adrenolytic activity were investigated in healthy volunteers. Study A subjects (n = 6) received single intravenous doses of 5 mg adimolol and single oral doses of 200 mg capsules, 200 mg tablets and 100 mg tablets on four occasions separated by at least two weeks. Study B subjects (n = 6) were given single intravenous doses of 5 mg and single oral doses of 100 mg of the 14C-labelled drug on two different occasions. Study C subjects (n = 6) were administered multiple oral doses of 100 mg adimolol daily for five days, and three weeks later 50 mg daily for five days. Adimolol plasma concentrations were assayed over seven days following each single dose using a specific and sensitive high-pressure liquid chromatographic method. The plasma concentration data obtained from the single i.v. dose studies were individually fitted to an open four-compartment model. To describe mathematically the single oral dose plasma level data, two compartments were added to the model to take care of the absorption. Irrespective of the route of administration, the doses and formulations given, all plasma concentration curves could be described with similar pharmacokinetic parameters. Plasma concentration curves predicted by the open four-compartment model were fully confirmed by the actual data obtained after chronic oral administration. The terminal half-life averaged 12 h following intravenous and 15 h after oral administration. The peak plasma concentration was reached on average 4 h following oral administration.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗
PubMed1985

[Diminished increase in body length in rats as an indicator of toxic injuries].

In four subchronic and three chronic toxicity studies in rats, in which the application of pharmacologically active substances led to a reduction in body weight development, the lengths of the animals were also measured. It could be shown that a lower body weight gain was always accompanied by a reduction in body length increase. With increasing doses or higher toxicity the within-group variations of individual values were smaller and the correlation between body weight and length of the rats was generally greater.

Aging↗
PubMed1985

[Statistical tests for bioequivalence].

The application of statistical tests of hypotheses in the evaluation of bioavailability studies is discussed. The necessity of correctly indicating the risk of false decisions in accordance with the hypothesis to be tested is emphasized. The procedure of evaluation presented here is performed analogously to the methods of the statistical quality control and always takes errors of the 1st kind and the 2nd kind into account. The advantageous use of the operating characteristic is pointed out. It is possible to read from these curves the effects which the size of the random sample and the experimental variation have on the reliability of the statement. The procedure is illustrated by means of numerical examples from literature.

Biological Availability↗