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Biomedical subjects

M Klemm

Publications and source records attributed to M Klemm.

At least 55 records · Page 3Linked to original sources
PubMed1993

[Physical technical calibration of a new self-tonometer].

The microprocessor-controlled applanation tonometer was calibrated in force measurement and area detection by using weights and silicon calibration pistons. This makes it possible to compare the technical precision of the instrument under standardized conditions and the results of previous clinical examinations. With the instrument in a vertical position, the force measurements meets the official calibration requirement. Force measurements in a horizontal position will follow in order to demonstrate that exact measurements can be taken with the instrument irrespective of position. A suitable method for calibrating the optical sensor by using the silicone pistons for area detection is shown. This method is to be extended by using calibration pistons of different diameters, which are within the permitted calibration tolerances.

Calibration↗
PubMed1993

[Optimizing the automatic self-tonometer by an acoustic control signal and changed fixation optics].

An automatic self-tonometer must fulfill special requirements from the point of view of precision as well as user-friendliness. The sensor that applanates the cornea must be perfectly centered on the vertex in order to measure the intraocular pressure correctly. The modified version of the self-tonometer has been equipped with an acoustic control signal and a modified fixation lamp that facilitate its use. In order to analyze the effectiveness of these hardware changes, we compared the modified tonometer to the existing self-tonometer in a randomized study with 30 patients. Reference was the Draeger hand-held applanation tonometer. The results show comparable precision; however, the percentage of error measurements in the modified tonometer was considerably lower. This is a definite improvement in the development of the self-tonometer.

Adolescent↗
PubMed1992

Structure of autonomic neuromuscular junctions in the sinus venosus of the toad.

The structure of cholinergic and adrenergic neuromuscular junctions in the sinus venosus of the toad, Bufo marinus, was determined by electron microscopy. From random sections of sinus venosus tissue it appeared that there were variable separations between cholinergic or adrenergic varicosities and the nearest sinus venosus muscle cell. However, when the structure of complete cholinergic and adrenergic varicosities was determined by examining serial electron micrographs, virtually all varicosities that lost their covering of Schwann cell were found to form an area of close apposition with an adjacent muscle cell. At the region of close apposition, the neuromuscular cleft was filled with a single layer of basal lamina to give a neuromuscular separation of about 70 nm. Synaptic vesicles within a varicosity were usually found to be concentrated towards the region of close apposition. These observations are discussed in relationship to the idea that when transmission occurs at these neuromuscular junctions the transmitters act on discrete pools of specialized subsynaptic receptors.

Animals↗
PubMed1992

Transmission at autonomic neuroeffector junctions.

For organs innervated by the autonomic nervous system, it is generally held that neuroeffector transmission is achieved by varicosities releasing transmitters some distance from the membranes of target cells. Transmitters are thought to diffuse through the extracellular space and interact with post-junctional receptors that are widely distributed over the cell membranes. This article presents an alternative view, suggesting that transmission can occur at organized neuroeffector contacts, that transmitters interact with restricted pools of specialized junctional receptors, and that many receptors on target cells are not involved in neuroeffector transmission.

Animals↗
PubMed1992

[Meningioma of the optic nerve sheath. Diagnostic problems despite use of modern imaging procedures].

In spite of modern optical examination techniques such as sonography, nuclear magnetic resonance tomography (NMR) and x-ray computer tomography up to now the meningioma of the optic nerve sheath still poses a problem in respect of differential diagnosis. This problem is illustrated by two case reports. In both patients a meningioma of the optic nerve sheath could be diagnosed only after various attempts using all the imaging techniques mentioned above. NMR in combination with Gadolinium injection gave most important information.

Cranial Nerve Neoplasms↗
PubMed1991

Subzonal microinjection of mouse spermatozoa: insufficient sperm motility might induce phagocytosis.

Acrosome-reacted CB6F1 mouse spermatozoa with slight flagellar motility were microinjected under the zona pellucida of CB6F1 mouse oocytes. Electron microscopy revealed the presence of swollen and decondensed sperm heads in the oocyte cytoplasm. Sixty-one percent of the microinjected oocytes reached a morphologically apparent two-cell stage, but chromosomal analysis demonstrated only haploid chromosomal complements in all cases. The exposure of microinjected oocytes to suspensions of spermatozoa of mice homozygous for a 2,4 reciprocal translocation resulted in normal fertilization and embryonic development with a maternally as well as a paternally derived haploid genome. Identical results were obtained with oocytes microinjected with medium and subjected to in vitro fertilization thereafter. Thus it can be suggested that the microinjected spermatozoa with insufficient flagellar motility are incorporated into the oocyte cytoplasm by phagocytosis. These spermatozoa do not induce a polyspermy block but induce the oocyte to parthenogenetic development.

Animals↗
PubMed1991

Mission statements: selling corporate values to employees.

This article investigates the reasons for the increasing use of the Company Mission Statement. Using information from a survey of U.K. companies in 1989 it looks at the types of statements issued by companies, their content, usage, and value to managers. Of particular interest is whether the mission is primarily used for the motivation of staff, or for external image building. Related issues are the value of the mission drafting process in bringing managers together to agree common objectives and the use of a hierarchy of statements to reconcile internal and external stakeholders' interests. The conclusion is that the Mission, which includes a statement of company values, is an important tool for managers to assert their leadership within the organization.

Data Collection↗
PubMed1987

Nonoptical definition of applanation surface.

Based on the Imbert-Fick law and the theoretical considerations of Goldmann, new applanation tonometers were designed, still using an applanation diameter of 3.06 mm to avoid a new biometric calibration. Three different electronic recording devices were used for the area assessment. An optical, a capacitance and a digital line sensor were tested in first calibration experiments.

Animals↗
PubMedDate not supplied

Permanent embryonic germ cell lines of BALB/cJ mice--an in vitro alternative for in vivo germ cell mutagenicity tests.

To offer a sensitive and predictive in vitro method to assess germ cell mutagenicity, we established primordial germ (PG) cell-derived permanent female and male embryonic germ (EG) cell lines of the mouse (strain BALB/cJ). The differences in developmental sensitivity of EG cells and differentiated fibroblast cells of the mouse cell line 3T3 to genotoxicants were tested comparatively under identical test conditions. Cytotoxicity assay was measured by the MTT test and genotoxic effects were determined by sister chromatid exchanges (SCE) rates induced by standard reference mutagens. Both methods are used to assign the chemicals to two classes of in vivo reproductive toxicity, non- and strongly genotoxic to germ cells. Applying linear discriminant analysis, a biostatistical prediction model (PM) was developed for the female cell line EG(3). This procedure identified a single variable, the Ig(SCE(200)EG(3)) as the statistically significant concentration related increase of 200% in the mean number of SCEs per metaphase spread after 3 h of exposure to be sufficient for separation into the classes: non- and strongly genotoxic to germ cells. Applying this PM to the training set of five genotoxic and three non-genotoxic test chemicals, 100% correct classifications were obtained.

3T3 Cells↗
PubMedDate not supplied

[Local school attendance by students with cancer during and after therapy].

The pilot project brought to attention in this study aims to improve social integration and reintegration at school of pupils inflicted by cancer. The guidelines include an intensive, long-range individual care and accompanied visits in the patients' own classes. Conversations are offered by hospital-teachers and, eventually, by physicians in the classroom proper. This approach results in reducing fear, insecurity and ignorance of both school-mates and teachers at the school of origin, thus mediating better human implications facing children and adolescents involved. The experience attained from over 80 visits in schools of origin indicates that these contacts strengthen the patients' prospects and reduce their social and school-associated problems in terms of promotising their psycho-social conditions.

Absenteeism↗