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Biomedical subjects

M Meyer

Publications and source records attributed to M Meyer.

At least 703 records · Page 39Linked to original sources
PubMed1976

Mutagenesis in bacteriophage T7. I. Chemically induced mutagenesis.

The mutagenesis in phage T7 after MMS-, HNO2-, hydroxylamine-, 5-BUdR-, and 2-AP-treatment in relation to host controlled functions is investigated. There was no dependence of the induction of mutations on the character of the host strains (rec, hcr). A back mutation system (amber system) and a forward mutation system (host range system) have been used. Substances which cause mainly transitions from GC to AT do not lead or only rarely lead to reversions of the amber system; but chemicals producing transitions from AT to GC do so.

2-Aminopurine↗
PubMed1976

Mutagenesis in bacteriophage T7. II. UV induced mutagenesis.

UV induced mutagenesis of bacteriophage T7 was investigated by using a forward mutation system (host range system) and a back mutation system (amber system). The results indicate a dependence of mutation of T7 after UV irradiation only on the rec gene controlled functions of the bacterial host. The functions controlled by pol and uvr genes have no influence. Among other types of mutations UV irradiation leads to transitions from AT to GC.

Caffeine↗
PubMed1976

Gas-blood CO2 equilibration in parabronchial lungs of birds.

We have conducted two experimental series in the chicken in order to study CO2 exchange in the parabronchial lungs of birds. In the first series, the animals were artifically ventilated and end-expired PCO2, PE'CO2, was measured and compared with mixed venous PCO2, PVCO2. On the average, PECO2 exceeded PVCO2 by 2.8 Torr. In the second series, rebreathing was used to investigate the mechanism of this positive (PE'-PV)CO2 difference. Lung gas PCO2 was found to equilibrate with PVCO2 if both CO2 and O2 exchange in the lung was abolished during rebreathing. Only if O2 uptake continued, we observed a positive gas-to-mixed venous blood PCO2 difference. The results suggest that positive gas-blood PCO2 differences both during rebreathing and steady-state ventilation are brought about by the Haldane effect. Model calculations show that in the homogeneous avian lung, unlike in the alveolar lung, the Haldane effect can produce positive (PE'-PV)CO2 differences during steady-state breathing due to the peculiarities of the crosscurrent arrangement and parabronchial ventilation and blood perfusion.

Animals↗
PubMed1976

[Therapeutic modification of blood circulation disorders of the intestine due to strophantin].

The vasoconstrictor effects of strophanthin on mesenteric hemodynamics were studied using mechanical ventricular massage to exclude the cardiac effects of the drug. The administration of a calcium antagonistic compound prior to digitalis, together with and after digitalis application, prevented the vasoconstrictor response completely. From our experimental experience the combination of cardiac glycosides with calcium antagonistic compounds seems rational.

Animals↗
PubMed1976

Weight-bearing deficiency of the 1st metatarsal ray.

The authors have analysed a special disturbance of the statics and dynamics of the forefoot - deficient weight-bearing on the first metatarsal ray whilst walking. From the clinical point of view, the condition resulted in the development of a dorsal bunion and metatarsalgia. Forty-nine cases were treated and seven causative factors were discovered: Club foot, Paralysis, Congenital deformity, Fracture-dislocation of Lisfranc's joint, Sequelae of surgery for hallux valgus, Sequelae of subtaler arthrodesis, "Functional" abnormality.

Adolescent↗
PubMed1976

Unsuitability of porcelain crucibles for dry ashing of biological tissues for calcium analysis.

At temperatures required for complete release of calcium from beef liver by dry ashing, porcelain crucibles release significant amounts of calcium into the ash, which leads to erroneously high calcium values in the samples. Heated, empty porcelain crucibles do not show released calcium. Both fused silica and platinum crucibles fail to show any significant interaction with the sample. Samples dry-ashed in fused silica crucibles were compared to samples subjected to the hot trichloracetic acid-acetic acid extraction method, which gave results not significantly different if the tissue was first minced. However, calcium was incompletely extracted by the hot acid from whole segments of liver weighing about 0.2 g.

Animals↗
PubMed1976

[Differential diagnosis of ptosis (author's transl)].

An accurate differential diagnosis of ptosis results if one refers the functional disorders of the levator to the different levels of the motor unit: Muscle, synapsis, peripheral neuron and nucleus. Therefore ptosis can be classified into myogenic, synaptogenic and neurogenic forms. This classification is also based on electromyographic findings from the levator muscle. Myogenic forms of the ptosis are: Senile ptosis, chronic progressive ocular muscle dystrophy, acute exophthalmic myositis and affections of the levator together with general systemic myopathies. Synaptogenic forms of ptosis are: Botulism and myasthenia gravis. Neurogenic forms of ptosis are: Cortical ptosis, ptosis from lesions of the oculomotor nucleus (congenital ptosis, Moebius-syndrome), peripheral oculomotor palsy, ptosis in aberrant third nerve regeneration, sympathetic ptosis (Horner-syndrome), ptosis in cases of paradoxic innervation such as the Duane retraction-syndrome and the Marcus-Gunn-Jaw-Winking-syndrome (ptosis linked with jaw movement). According to the classification in myogenic, synaptogenic and peripheral-neurogenic forms of ptosis, the therapeutic possibilities (medical, surgical etc.) are discussed.

Blepharoptosis↗
PubMed1975

A quantitative electron microscopic analysis of the keratinizing epithelium of noral human hard palate.

The epithelium of normal human hard palate was subjected to sterologic analysis. Ten biosies were selected from a total of twenty specimens collected from 9 to 16 year old females, and processed for light- and electron microscopy. At two levels of magnification, electron micrographs were sampled from three strata (basale, spinosum, granulosum) in two locations (epithelial ridges and portions over connective tissue papillae). Stereologic point counting procedures were employed to analyse a total 1560 electron micrographs. In general, the thickness of the palate epithelium was 0.12 mm (over papillae) and 0.31 mm (in ridges), the epithelium is distinctly stratified, and homogeneously ortho-keratinized. From basal to granular layers, the composition of strata revealed decreasing densities of nuclei, mitochondria, membrane-bound organelles and aggregates of free ribosomes. Keratohyalin bodies and membrane coating granules increased, and cytoplasmic filaments with a constant diameter of about 85 A increased from 14 to 30% of cytoplasmic unit volume. The cytoplasmic ground substance occupied a stable 50% of the epithelial cytoplasm in all strata. The composition of basal layers in ridges differed from that over connective tissue papillae. The data are discussed in relation to the observations that (1) an increasing gradient of filament density is not the most characteristic feature of ortho-keratinizing oral epithelium and (2) differences in the degree of differentiation in cells of the stratum basale coincided with the comparable frequency distribution pattern of dividing cells.

Adolescent↗
PubMed1975

[Renal papillary necrosis in an infant].

Report of a case of renal papillary necrosis in an infant, following acute dehydration with cardio-vascular failure. Evolution was favourable and diagnosis was established retrospectively by I.V. urogram.

Acidosis↗
PubMed1975

[Ball cells and the structure of the epidermis of anuran larvae. I. Ascaphus truei Stejneger].

1. A special cell numerously occuring in the epidermis of the anuran larva of Ascaphus truei which must be called ball cell because of its usual shape, more thoroughly has been investigated by microscope. Especially plain preparations besides cross sections stained in customary way, respectively worked up histochemically with regard to orientation, were used for that. 2. The ball cell-the very characteristical epidermal attribute of Ascaphus larva-is an exocrine element with apparently far extending continuous merocrine secretion. The product contains mucous substances partly being of acid kind. The activity in any case is extending to metamorphosis. 3. Altogether the cells are forming a simple endoepidermal plain gland with differently displayed parts: strong condensation of the elements, for instance, in a circumoral zone, scanty distribution in the whole middle back over all.

Animals↗
PubMed1975

[Epidermal ball cells of the Ascaphus truei Stejneger (Amphibia, Salientia, Ascaphidae) larva: a biometric contribution].

1. With regard to orientation the in the larva of Ascaphus truei characteristic excretory special cell (mucosa cell) was analysed in plain preparations of epidermis from head-trune in four test regions - praeoral, postoral, craniodorsal and post spiracle -, the speciman (stage 32 according to Gosner 1960) being investigated was excellently fixed, 50 cells at times biometrically are used therefore. The element with adequate safety must be called ball cell because of its shape. 2. Elements only praeoral present a more little volume dividing from other average (and more unimportant occurence of an outlet). In respect of frequency distribution of different big ball cells in whole material significant differences are missed. A definite size of volume independent of region is prefered. 3. In 69% of all ball cells being considered there is an outlet, the existence is not fixed to a definite volume of cell. Shape of opening in 88% is round to a little ellipsoidal, its size is reaching to 10% more than half of maximal flat plain of cells; with regard to regions differences are absent. 4. In 3 regions thereupon being investigated (postoral, craniodorsal and post spiracle) a real correlation exists between height of single ball cells and thickness of epidermis.

Amphibians↗