Biomedical subjects

F Müller

Publications and source records attributed to F Müller.

At least 307 records · Page 17Linked to original sources

PubMed1989

The temperature and pH dependence of some properties of p-hydroxybenzoate hydroxylase from Pseudomonas fluorescens.

The free and complexed flavoprotein, p-hydroxybenzoate hydroxylase, was studied by light-absorption, circular-dichroism and fluorescence techniques as a function of the pH. The following compounds served as ligands for the enzyme: p-hydroxybenzoate, p-fluorobenzoate, benzoate, p-aminobenzoate and tetrafluoro-p-hydroxybenzoate. Depending on the technique used, the various ligands exhibit pH-dependent physical properties and dissociation constants. The data can be fitted with pKa values in the range 7.7-7.9. It is suggested that this pKa value belongs to a tyrosine residue in the active center of the enzyme. This assignment is supported by published data and additional experiments.

4-Hydroxybenzoate-3-Monooxygenase↗

PubMed1989

13C, 15N, and 31P NMR studies on 6-hydroxy-L-nicotine oxidase from Arthrobacter oxidans.

The interaction between the apoprotein of 6-hydroxy-L-nicotine oxidase from Arthrobacter oxidans and the prosthetic group FAD has been investigated by 13C, 15N, and 31P NMR techniques. The FAD prosthetic group was selectively enriched in 13C and 15N isotopes by adding isotopically labeled riboflavin derivatives to the growth medium of riboflavin-requiring mutant cells. In the oxidized state the chemical shift of the C(7) and C(8) atoms indicates that the xylene moiety of the isoalloxazine ring is embedded in a hydrophobic environment. The polarization of the isoalloxazine ring as a whole is, however, much more comparable to that of free flavin in a polar and protic environment than to free flavin in an apolar environment. The polarization of the ring system can be ascribed to strong hydrogen bonds between the apoprotein and the two carbonyl groups. The binding of the competitive inhibitor, 6-hydroxy-D-nicotine, influences the resonances of the C(4a) and the N(5) atoms strongly. It is suggested that these shifts are due to a strong hydrogen-bonding interaction between the N(5) atom and the inhibitor. On reduction all resonances, except those of the C(10a) and the N(1) atoms, shift upfield, indicating the increased electron density in the ring system. In the dithionite-reduced enzyme, the ring system is bent at the N(5) position. Due to the bending of the N(5) atom and the sp2 hybridized N(10) atom, electron density from the N(10) atom is reallocated at the C(4) carbonyl group. In contrast, in the substrate-reduced enzyme the N(5) atom is almost completely sp2 hybridized, yielding a rather planar isoalloxazine ring.(ABSTRACT TRUNCATED AT 250 WORDS)

Arthrobacter↗

PubMed1989

Bidirectional closure of the rostral neuropore in the human embryo.

The length of each neuropore was measured in 23 human embryos of stages 10-12 (about 22-26 days), and the closure of the lips of the rostral neuropore was studied in 24 embryos of stage 11 (about 24 days), with particular reference to the terminal lip. Graphic reconstructions were prepared from two particularly suitable examples, and mitotic figures were plotted for one of these. The lengths of the rostral and caudal neuropores are basically similar, but the rostral opening closes 1 day earlier and more abruptly (within a few hours) than the caudal (which takes a day). Closure of the rostral neuropore in the human embryo is bidirectional, proceeding simultaneously from 1) midbrain and diencephalon 2 and 2) the telencephalic region adjacent to the chiasmatic plate. Species differences are emphasized. Closure at the terminal lip of the neuropore is by fusion of right and left neural folds, as occurs elsewhere during primary neurulation. The rostral end of the neural plate in the median plane is, in the human embryo, at the rostral limit of the chiasmatic plate. Histological differences, however, exist between closure at the terminal lip and that at the dorsal lip: the surface epithelium plays a more significant role at the terminal lip, and the seam is more visible and presumably stronger. In future anencephaly it has been found that fusion at the terminal lip may occur, although that at the dorsal lip is deficient.

Anencephaly↗

PubMed1989

Mediobasal prosencephalic defects, including holoprosencephaly and cyclopia, in relation to the development of the human forebrain.

Four very early synophthalmic embryos were studied in serial sections and reconstructed graphically by the point-plotting method. Three belonged to stage 16 (5 weeks) and one to stages 19/20 (7 weeks). Recently completed accounts and reconstructions of the normal brains of staged human embryos served as controls for comparison with the abnormal examples. The embryos shared in common: holoprosencephaly, arhinencephaly sensu stricto (absence of olfactory nerve fibers, bulbs, and tracts), presence of a proboscis, synophthalmia with two lens vesicles, a retarded telencephalic wall, absence of the mediobasal part of the telencephalon (the future septal area and the commissural plate: future anterior commissure and corpus callosum), irregularity of the diencephalon, mensural changes in the brain, absence of the rostral part of the notochord and consequent cranial defects, and small ganglia of the cranial nerves. Where it could be determined (at least in the three less advanced specimens), the adenohypophysial primordium was either small and isolated or was absent; a tentorial condensation appeared to be missing; and disturbances of the primordia of the orbital muscles and their innervation were noted. The corpus striatum is single and corresponds to only the diencephalic part (medial eminence) of normal embryos. Interference with induction by the prechordal plate at or before stage 8 (18 days) would be expected to affect the future mediobasal part of the neural plate (median prosencephalic dysgenesis) and the future optic primordium (cyclopia sensu stricto). Insufficient formation of material from the prechordal plate would account for disorders of the orbital musculature and, possibly, for inadequacy of the tentorium cerebelli. Disturbance a couple of days later (stage 9) would result in synophthalmia. Cyclopia and synophthalmia entail arhinencephaly and holoprosencephaly, both of which may arise independently. Defective distribution of the cephalic mesenchyme points to a derangement of the mesencephalic neural crest (stages 10 and 11), causing such features as an incomplete chondrocranium and reduction in size of the ganglia of the cranial nerves. Failure of bilateral division of the telencephalon would occur at or before 4 weeks (stages 13 and 14). It is concluded that all the above conditions arise during the first 4 postovulatory weeks.

Abnormalities, Multiple↗

PubMed1989

Interpretation of some median anomalies as illustrated by cyclopia and symmelia.

Anomalies that involve the median plane are heterogeneous, and their embryological basis varies widely. Cyclopia and symmelia present a number of similarities: 1) They would appear to arise by neither fusion nor merging but mainly through a failure in lateralization. 2) Mesenchymal deficiency is important in both: possibly disturbance of the prechordal plate in cyclopia and failure of the caudal eminence in symmelia. The caudal eminence is an important developmental feature that is only recently becoming clearer in the human embryo. 3) Disturbance of axial material seems to be essential in both. 4) The results of experimental teratogenesis and an analysis of normal human development confirm that these conditions arise early. The teratogenetic termination-periods in the human are probably 2 1/2 weeks for cyclopia sensu stricto (a median eye in a single orbit) and 3 weeks for cyclopia sensu lato, i.e., synophthalmia (paired ocular structures in a single orbit); 2 1/2 weeks for symmelia of the upper limbs (e.g., in cephalothoracopagus) and 3 1/2 weeks for symmelia of the lower limbs in a single individual. It is pointed out that in symmelia the limb buds, upper or lower, have failed to separate at their postaxial margins. This is in contrast to dimelia, in which the preaxial borders are missing and the postaxial margins are duplicated (postaxial dominance).

Humans↗

PubMed1989

The human brain at stage 17, including the appearance of the future olfactory bulb and the first amygdaloid nuclei.

The growth of the cerebral hemispheres rostrally and caudodorsally brings about a deepening of the interlongitudinal fissure, in which blood capillaries for the future choroid plexus develop. Accumulation of mesenchyme basally presages the formation of the nasal septum. The olfactory bulb and tubercle become outlined. The three main areas of the telencephalon, future archi-, paleo-, and neocortex, can be recognized. The amygdaloid body, which is related to the medial ventricular eminence, contains either one or two nuclei. Nerve fibres from the olfactory tubercle arrive and pass through the amygdaloid area. The first indication of a septal nucleus is recognizable. The lateral ventricular eminence is present but not pronounced. The hemispheric stalk joins the cerebral hemispheres to the ventral thalamus and to the diencephalic part of the medial ventricular eminence. The beginning of the future choroid plexus consists in the formation of blood vessels and necrotic changes in the roof of the telencephalon medium and in rostral growth of the anterior choroid artery. Necrotic processes in the future choroid epithelium are now localized at the periphery of the still multilaminar tissue. The sulcus medius and zona intrathalamica delimit the dorsal from the ventral thalamus. The dimesencephalic borderline passes through the commissural fibres in the roof: the rostral part of the commissure is the posterior commissure, the caudal part, the commissure of the superior colliculi. In the mesencephalon, the red nucleus has a laterorostral position with regard to the nucleus of the oculomotor nerve. The cells of the locus coeruleus are well distinguishable. The gustatory fibres begin to separate from the common afferent tract as the tractus solitarius. Inferior and superior salivatory nuclei are delineated.

Amygdala↗

PubMed1989

The human brain at stage 16, including the initial evagination of the neurohypophysis.

Thirty-nine sectioned embryos of stage 16 were studied. Up to this stage the amygdaloid body is derived entirely from the medial eminence, which was purely diencephalic in stage 14, but now extends also to the telencephalon. The area of the future olfactory bulb is indicated by the presence of olfactory fibres entering the brain wall; the future olfactory tubercle is characterized by cellular islands. The presence of the hippocampal thickening and various histological features make it possible to outline the main, future cortical areas already at this early stage: archi-, paleo-, and neopallium. Hippocampus and area dentata correspond to the areas identified by Hines (1922) and Bartelmez and Dekaban (1962) but not to those identified by Humphrey (1966). The interventricular foramen is wide. The cerebral hemispheres grow rostrally and dorsally, thereby forming the beginning of the longitudinal fissure. Apart from the commissure of the superior colliculi, which began to appear in advanced embryos of stage 14, fibres of the posterior commissure are now present in some specimens. The neurohypophysis is apparent in fewer than half of the embryos. The marginal ridge (zona limitans intrathalamica) separates the dorsal from the ventral thalamus. Cranial nerve 3 emerges from M2. M1 has become shorter. Important pathways are beginning: the olfactory route by the olfactory fibres and the medial forebrain bundle; the vestibular by vestibulocerebellar and vestibulospinal fibres; gustatory by chorda tympani, nervus intermedius, and tractus solitarius. Fibres of the cochlear nerve are noted. The first parasympathetic ganglia, submandibular and ciliary, are identifiable. Asymmetry of the cerebral hemispheres was noted in one specimen.

Brain↗

PubMed1989

Molecular cloning and sequence determination of the lpd gene encoding lipoamide dehydrogenase from Pseudomonas fluorescens.

The lpd gene encoding lipoamide dehydrogenase (dihydrolipoamide dehydrogenase; EC 1.8.1.4) was isolated from a library of Pseudomonas fluorescens DNA cloned in Escherichia coli TG2 by use of serum raised against lipoamide dehydrogenase from Azotobacter vinelandii. Large amounts (up to 15% of total cellular protein) of the P. fluorescens lipoamide dehydrogenase were produced by the E. coli clone harbouring plasmid pCJB94 with the lipoamide dehydrogenase gene. The enzyme was purified to homogeneity by a three-step procedure. The gene was subcloned from plasmid pCJB94 and the complete nucleotide sequence of the subcloned fragment (3610 bp) was determined. The derived amino acid sequence of P. fluorescens lipoamide dehydrogenase showed 84% and 42% homology when compared to the amino acid sequences of lipoamide dehydrogenase from A. vinelandii and E. coli, respectively. The lpd gene of P. fluorescens is clustered in the genome with genes for the other components of the 2-oxoglutarate dehydrogenase complex.

Amino Acid Sequence↗

PubMed1989

Nitroblue tetrazolium reduction in monocytes and monocyte-derived macrophages. Effect of oxidative burst stimulants and interferons.

The ability to mount an oxidative burst (OB) in response to medium, zymosan and phorbol myristate acetate (PMA) was assessed in human blood monocytes cultured for 1 day (MO) and monocyte-derived macrophages cultured for 10 days (MDM). Further, the effect of recombinant interferons (IFNs) on OB generation was examined. The OB was measured as a reduction of nitroblue tetrazolium (NBT). Unstimulated and stimulated NBT reduction per cell nucleus and the ratio of stimulated/unstimulated NBT reduction was not significantly different in cells cultured for 1 and 10 days. In MO, IFN-gamma stimulated the OB when co-stimulated with zymosan or PMA. IFN-alpha reduced MO adherence. When the lower adherence was corrected for, IFN-alpha enhanced NBT reduction. In MDM, a high concentration of IFN-gamma stimulated the OB without co-stimulation, in lower concentrations the presence of a co-stimulant was necessary for OB stimulation. IFN-alpha/beta enhanced the OB in response to PMA, suggesting that IFN-alpha/beta has a role in macrophage activation.

Cell Adhesion↗

PubMed1989

Altered IgG-subclass distribution in lymph node cells and serum of adults infected with human immunodeficiency virus (HIV).

The relative distribution of cells producing subclasses of IgG or IgA was examined by immunohistochemistry in lymph node biopsy specimens from 15 adults with persistent generalized lymphadenopathy due to infection with HIV and from 11 adults with lymph nodes enlarged from other causes. The IgG1 immunocyte fraction was significantly higher and the IgG2 fraction significantly lower associated with HIV infection than in the controls. The proportions of cells producing IgG3, IgG4, IgA I or IgA2 were similar in the two lymph node categories. The altered IgG-subclass distribution of immunocytes in HIV lymphadenopathy concorded with the serum levels that were significantly elevated for IgG1 and lowered for IgG2 compared with a panel of blood donor samples.

Adolescent↗

PubMed1989

[Atlas of stages of development of the human embryonic brain with graphic reconstructions of the median plane].

Reconstructed median sections of staged human embryos were prepared to provide fundamental insight into the developing human brain. 1. At its first appearance as neural plate at stage 8 and even better visible at stages 9 and 10, the rostral end of the CNS is at the chiasmatic plate, that is, at the rostral end of the diencephalon. The telencephalon is a later acquisition. 2. The main parts, already visible in the neural plate, become arranged as neuromeres as the neural tube develops. The neuromeres, defined by definite morphological features, are transversely arranged originally. As morphological entities they are visible longest in the rhombencephalon (up to stages 17-18). 3. The initially uniformly thick walls at stages 12 and 13 develop thickenings: medial and lateral eminences in the forebrain constitute parts of the corpus striatum. The hippocampus forms as a rostrocaudally growing C-shaped thickening in the medial wall of the cerebral hemisphere. The ventricular bulge develops in the alar areas of Rh 1 and the isthmic segment, and develops into the corpus cerebelli. 4. Internal sulci are important landmarks. The sulcus limitans separates alar and basal plates in the rhombencephalon and mesencephalon, but it does not continue into the forebrain. The hypothalamic sulcus separates the hypothalamus from the thalamus (epi-, dorsal, and ventral thalami); the sulcus circularis separates the olfactory bulb from the olfactory tubercle. 5. The embryonic brain develops from approximately day 18 to day 57, i.e., during a period of 5 1/2 weeks. It progresses from a neural plate to a highly complicated, almost spherical organ, parts of which, to judge from their morphology, should be capable of functional competence.

Anatomy, Artistic↗

PubMed1989

Zuclopenthixol and haloperidol/levomepromazine in the treatment of elderly patients with symptoms of aggressiveness and agitation: a double-blind, multi-centre study.

A double-blind study was carried out in 48 hospitalized, elderly demented patients with key symptoms of aggressiveness and agitation to evaluate the efficacy and tolerability of zuclopenthixol compared with that of haloperidol/levomepromazine. Patients were allocated at random to receive initial doses of either 4 mg zuclopenthixol daily or 1 mg haloperidol in the morning and 5 mg levomepromazine in the evening over a period of 4 weeks. In Week 4, the mean daily dose was 4.8 mg zuclopenthixol and 1.6/7.6 mg haloperidol/levomepromazine, respectively. After 1 week, the severity of illness was already significantly reduced, and was further reduced after 2 and 4 weeks of treatment in both groups: the reduction, however, was most pronounced in the zuclopenthixol group and after 2 weeks this difference was significant. Side-effects were few. The results of the study indicate that, whilst both zuclopenthixol and haloperidol/levomepromazine were effective and well tolerated in these elderly patients with aggressiveness and agitation, onset of therapeutic effect appeared more rapidly with zuclopenthixol, which furthermore provides the practical advantage that it may be administered once a day.

Aged↗

PubMed1989

[Biofeedback as a part of the treatment of mandibular dysfunctions].

50 patients were treated with analogous acoustic EMG biofeedback in 5 sessions of 20 minutes each. 75% of the patients experienced improvement both of the clinical signs and their subjective symptoms. It is emphasized that 1. biofeedback training with acoustic analogous EGM biofeedback may support successful treatment of mandibular dysfunctions and 2. stress reduction and pretreatment with bite planes may increase the probability of successful treatment.

Adolescent↗

PubMed1989

[Scintigraphy of sustained-release agar-embedded insulin suppositories].

In earlier publications [1-3] we reported on the retardation and protective effect of insulin-agar-embeddings in triglyceride suppositories by in vitro and in vivo tests on rabbits. The discovered effects were visually followed by gammascintigraphic test of adequate rectally applied 131I-insulin-specimens in the rectum and thyroid gland and, in relation with the glucose lowering course, the liberation, distribution and bioavailability of the immobilized hormone was illustrated.

Agar↗

PubMed1989

[Glucose utilization in adipose tissue of rats in chronic somatotropin deficiency].

Injections of monosodium glutamate to neonate rats induce chronic growth hormone deficiency by hypothalamic lesions in the regions of the nucleus arcuatus and the eminentia mediana. The glutamate treated rats develop massive obesity. By this type of obesity hyperinsulinemia in the dynamic phase is not evident. The adipose tissue of the GOR (glutamate obese rat) is characterized by hypertrophic adipocytes and diminished number of adipocytes. In the GOR glucose oxidation and glucose lipid conversion are increased, but insulin sensitivity of glucose metabolism is diminished. The enhanced glucose utilization in adipose tissue of the GOR is discussed as being the consequence of the chronic growth hormone deficiency.

Adipose Tissue↗

PubMed1989

[Cervical ectopic thymus].

Two cases of cervical aberrant thymus in infants are reported; it's important to identify such ectopia because thymic tissue involutes spontaneously later on; neither surgery nor other treatment is needed. Ultrasonography is a method of choice for tissue characterization of ectopic thymus and differential diagnosis with other cervical masses.

Diagnosis, Differential↗

PubMed1989

[The anticomplementary effect of animal sera--a contribution to the precise definition of the complement-binding reaction].

Photometric procedures (standardised complement fixation reaction) were used to determine the anticomplementary action of animal sera. Multiplication factors, K, of 3.0 to 5.0, related to human sera, were recorded and were found to be capable of reducing or offsetting anticomplementary serum action in CFR in terms of a definitive complement excess. Anticomplementary action of animal sera, for all practical purposes, does no longer apply to dilution ratios of 1:16. The complement excess necessary for titres of 1:4 and 1:8 should be precisely defined and can then be calculated in constant measures. Hence, titres of 1:8 may be rendered accessible to safe assessment. Titres of 1:4 will continue to be problematic. The following order of animal sera was defined in comparison to human sera: cattle, pigeon, duck, sheep, cat, turkey, swine, coypu, hen, dog.

Animals↗

PubMed1989

Effect of gliadin on the distribution of sucrase among different fractions of fetal chick intestine.

The effect of peptic-tryptic digested gliadin (PT-gliadin) on the increase in sucrase activity in different fractions of tissue cultured fetal chick duodenum was investigated and compared with that of monensin, a known perturbant of the Golgi complex. PT-gliadin diminished the rise in sucrase activity in the tissue homogenate, in a brush border fraction, and in the high speed supernatant, whereas the activity in a Ca2+-pelleted fraction including endoplasmic reticulum and Golgi apparatus was unaffected. In contrast, monensin caused a proportional inhibition of the increase in sucrase activity in all fractions examined. The findings might suggest that PT-gliadin is able to affect intracellular processing of sucrase with the site of attack being distal to that of monensin in the biogenesis of the enzyme. Whether the effect of PT-gliadin on fetal gut is relevant also for celiac intestine remains to be established.

Animals↗