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Biomedical subjects

F Müller

Publications and source records attributed to F Müller.

At least 469 records · Page 26Linked to original sources
PubMed1981

The first appearance of the human nervous system at stage 8.

Eleven embryos of stage 8 (18 days), including a set of twins, were studied in detail and graphic reconstructions were prepared. This is the first report based on more than two specimens, as well as the first account of embryos of excellent histological quality at this developmental stage. Detailed measurements of the embryos are provided. It is found that the neural groove, which is the first morphological manifestation of the nervous system, is present in one quarter of embryos of stage 8. The neural folds are very largely cerebral rather than spinal. Correlations with other developmental features suggest that the neural groove is seen only when a certain degree of size and maturity has been reached by embryos of this important stage.

Anthropometry↗
PubMed1981

Na dependence of monosaccharide absorption in isolated rabbit small intestine, perfused through lumen and vascular bed.

Na dependence of D-glucose and 3-O-methyl-D-glucose absorption was investigated using the isolated rabbit small intestine perfused through the lumen and the vascular bed, thus imitating in vivo conditions. No dependence of monosaccharide transport of luminal Na concentration was demonstrable if the lumen was perfused at low flow rate. Due to Na secretion, however, Na concentration in the lumen bulk phase, initially being zero, was raised to more than 20 mmol/l during the course of the experiments. Na dependence of sugar transport could be shown, however, if (1) Na secretion was decreased (by use of a vascular medium with low Na concentration) or if (2) unstirred layer thickness was reduced (by enhancement of luminal flow rate). Both conditions allowed the Na concentration near the brush border membrane to be controlled. The results provide an experimental explanation for the apparently low degree of Na dependence of monosaccharide absorption under in vivo conditions.

3-O-Methylglucose↗
PubMed1981

Bacterial bioluminescence: Spectral study of the emitters in the in vitro reaction.

Transient fluorescent species are observed in the bioluminescent reactions of three reduced flavin mononucleotides with aliphatic aldehydes and oxygen, catalyzed by bacterial luciferase. In each case the fluorescence spectral distribution is similar to that of the bioluminescence but is readily distinguishable from it on the basis of a significantly greater signal strength. The corrected bioluminescence maxima using Beneckea harveyi luciferase are 479 nm (iso-FMNH(2)), 490 nm (FMNH(2)), and 560 nm (2-thio-FMNH(2)). In an ethanol glass at 77 K, 2-thioriboflavin is fluorescent (varphi(F) = 0.03, lambda(max) = 562 nm). These results are interpreted by a sensitized chemiluminescence mechanism in which the flavins bound to luciferase act as acceptors of excitation energy. For 2-thio-FMNH(2), this acceptor species appears to be the oxidized 2-thio-FMN on the basis of the spectral evidence, whereas for the other flavins, some form of reduced species is a more likely candidate.

Journal Article↗
PubMed1981

On the molecular and submolecular structure of the semiquinone cations of alloxazines and isoalloxazines as revealed by electron-paramagnetic-resonance spectroscopy.

The thermodynamically stable and, therefore, analytically most important alloxazine and isoalloxazine radical cations have been studied in detail by electron paramagnetic resonance (EPR) spectroscopy. Isotopic and chemical substitutions have been made as in earlier studies with the less stable neutral and anionic species. The experimental spectra have been calculated with the aid of a more sophisticated computer-simulation program than previously used. Excellent fits were obtained only when all of the following atoms were taken into account in the hyperfine coupling scheme: N-5 H, N-10 H or CH3, C-6 H, C-7 H, C-8 H or CH3 and C-9 H. An additional but small coupling constant was required for the fit. This latter coupling constant is assigned to the nitrogen atom(s) of the pyrimidine subnucleus of (iso)alloxazine radical cations. The EPR-active proton is attached to N-5 as we also found for the neutral flavosemiquinone. The alloxazine and isoalloxazine radical cations exhibit an identical hyperfine coupling scheme but differ especially in the pyrazine nucleus with respect to the spin density distribution. This suggests that the geometrical structure of the two kinds of radicals is somewhat different. The highest spin density is, however, located at N-5 of (iso)alloxazine as has been found for the other flavosemiquinone species. The hyperfine coupling constants are interpreted in terms of spin densities and comparison is made with the most recently available quantum chemical calculations. All monomeric flavosemiquinone species are compared with each other and their differences in the submolecular structure are discussed briefly.

Benzoquinones↗
PubMed1981

Treponema-specific and antilipoidal 19S(IgM) antibodies in penicillin-treated and untreated rabbits after infection with Treponema pallidum.

The titres of treponema-specific and antilipoidal 19S(IgG) antibodies were determined in rabbits infected intratesticularly with Treponema pallidum. One group of rabbits was treated with penicillin the other served as control. Using different serological tests it was shown that 19S(IgM) antibodies were still detectable eight months after infection at about the same titres in both groups. In contrast, 19S(IgM) antibody titres in patients with syphilis became undetectable within three to six months after penicillin treatment. It is suggested therefore that the rabbit is not a reliable model for studying the effect of penicillin in human T pallidum infections.

Animals↗
PubMed1981

[Problems in the determination of pancreatic enzymes for the quantitative functional diagnosis of the pancreas in children].

Pancreozymin-secretin tests were carried out in children aged from 0,5 till 12 years by means of a two lumen tube of the Salem-Sump-type and a three lumen perfusion tube. For stimulation we used 2 U/kg of the hormones, each from BOOTs-Corp. Amylase was determined with dinitrosalicylic acid, lipase by titration of acidic equivalents after half hour incubation and trypsin and chymotrypsin with TAME and BTEE respectively. We used PEG 4000 as marker and quantified enzymes secretion as well as liquid secretion by it. We got up to 50% lower results by testing with the two lumen tube. If we are laying the perfusion tube we measured an elevation of the two lumen tube. If we are laying the perfusion tube we measured an elevation of the II-hydroxycorticoides. The concentration of the enzymes in the specimines before perfusion on 3 consecutive days fell by 90% on the average. We discussed some problems of the determination of enzymes and performing of the tests by means of the results.

Amylases↗
PubMed1981

[Introduction to the study of embryonic stages in man].

The internationally accepted Carnegie system of 23 developmental stages for the embryonic period proper (the first 8 post-ovulatory weeks) is outlined. At the end of this period the human embryo measures about 30 mm in C.-R. length. Some common misusages are noted, e.g., arabic numerals should be used for the states and the term "horizon" is obsolete; embryonic length is not a stage; STREETER's ages were based on the macaque and do not apply to the human. The introduction includes a discussion of the Carnegie Embryological Collection, the embryonic period, developmental stages, and finally a guide to embryonic staging in the human. An atlas of photographs of external views of embryos at the various Carnegie states is provided. Stages 1 to 8 (the presomite period, up to about 18 days) are described briefly and illustrated with photographs and photomicrographs. Stages 9 to 12 (the somitic period, about 20 to 26 days) and stages 13 to 23 (the postsomitic period, 4 to 8 post-ovulatory weeks) are summarized with reference to both external and internal development, and illustrated with photographs of the external appearances. In addition to (A) certain references cited in the introduction and in the text, the bibliography includes : (B) an annotated list of general works on staged human embryos, (C) an annotated list of selected examples of stages 1 to 15, and (D) an annotated list of references to information concerning staged embryos arranged according to the various systems of the body.

Bibliographies as Topic↗
PubMed1980

The early development of the nervous system in staged insectivore and primate embryos.

The early development of the nervous system was studied in stage embryos of hemicentetes semispinosus, Microcebus murinus, Alouatta seniculus, Cebus appella, Cebus albifrons, macaca mulatta, and Homo sapiens. The specimens were assigned to Carnegie stages 11-13. Serial transverse sections were examined and graphic reconstructions were prepared. The early development of the neural tube is basically similar in all the species investigated but differences in detail are noticeable. The mesencephalic flexure serves in all cases as a landmark for malpighi's tripartite subdivision of the brain. The nonhuman embryos seem to show a little more variation than the human in the closure of the neuropores in relation to somitic count. With the exception of the later-appearing terminal-vomeronasal component, all major portions of the neural crest as classified by O'Rahilly ('65) are represented in both the nonhuman and the human embryos studied. No crest is present at the level of rhombomere 1, nor at rhombomere 3 except in the platyrrhines and some human embryos, nor at rhombomere 5 except in certain human specimens. An indication of the division of the trigeminal ganglion into its primary divisions is rare at stage 11 (C. apella), may be visible at stage 12 (Alouatta, macaca, Homo), and is definite (in Homo) at stage 13. Ganglionic contributions from head ectoderm (epipharyngeal placodes), as previously described in the human and some other vertebrate embryos, were sought and found in Cebus apella. In both nonhuman and human, a tendency is noted whereby the rostral limit of the occipitospinal crest, high at stage 11, seems to descend relatively at stage 12, and ascend again at stage 13 (at least in the human) to become associated with the appearance of the accessory and hypoglossal nerves. In general, the motor components of the nerves are identifiable before the sensory elements, and, in the present study, nerve fibers were first observed in the human at stage 13 in some of the cranial nerves and in the ventral roots of the spinal nerves.

Animals↗
PubMed1980

The human chondrocranium at the end of the embryonic period, proper, with particular reference to the nervous system.

The chondrocranium at stage 23 (27-32 mm C.-R., 8 postovulatory weeks) was studied in detail to fill the descriptive gap between 7 and 9 weeks. Serial sections of ten embryos, all belonging to the same developmental stage, were investigated and compared. Graphic and Perspektomat reconstructions were made from three embryos. The chondrocranium forms a continuous mass of well-formed cartilage, which blends with early cartilage in the nasal, orbital, and otic regions, around the future foramen rotundum, and at the site of the parietal lamina. The chondrocranium and "membrane" bones cover a relatively small portion of the brain, namely 1) the medulla and pons, 2) the caudal half of the lateral portion of the cerebellar primordium, and 3) the rostroventral part of the cerebral hemispheres. The relationships of the cranial nerves were are also investigated. The degree of cranial development is intermediate between that at stage 20 (21 mm) studied by Lewis (the only other skull so far studied adequately in a staged embryo) and that of fetuses of 40 and 43 mm investigated by Macklin. On the whole, the resemblances to the fetal skulls are greater: ossification is beginning in the tectum posterius (to form the supraoccipital), and most of the "membrane" bones (except the parietal, tympanic, lacrimal, and nasal) show osseous areas. The foramen rotundum is present. The lower angle between the chordal and prechordal parts of the basal stem ranges from 129 degrees (which resembles that at stage 20, namely 122 degrees) to 115 degrees (which is the same as that at 40-43 mm). An orbito-parietal commissure is not yet present. The lower border of the larynx is at the level of the lower border of the fourth cervical vertebra. In the larynx, the thyroid laminae have usually not fused, the hyoid cartilage possesses greater and lesser cornua, the cricoid cartilage displays its signet-ring form, and the arytenoids are identifiable as condensed mesenchyme with some early cartilage. The cartilage of the first pharyngeal arches is covered in its ventral three-fourths by an osseous mandibular plate. Morphological variations within stage 23 are minor and appeared not to be related closely to each other, so that it was not possible to arrange the embryos in a linear developmental series based on their level of cranial morphogenesis.

Brain↗