PubMed Health⌕ Search

Biomedical subjects

M Neumann

Publications and source records attributed to M Neumann.

At least 127 records · Page 7Linked to original sources
PubMed1996

Noise in models of neurological and psychiatric disorders.

The concept of noise has only recently been applied to modelling neuropsychiatric disorders. Two examples of such models are presented. 1. A phantom limb is a neurological condition after the amputation of an extremity. It consists of sensations of the presence of the lost limb and has been attributed to cortical as well as non-cortical mechanisms. A neural network model of phantom limbs is proposed which can parsimoniously account for a large number of clinical features and recent findings of cortical map plasticity after deafferentation. In trained self-organizing feature maps, deafferentation was simulated. Reorganization is shown to be driven by input noise. According to the model, the production of input noise by the deafferented primary sensory neuron drives cortical reorganization in amputees. No such noise is generated and/or conducted to the cortex in paraplegics. 2. Several clinical features of schizophrenia have been related to the ratio of signal to noise in neuronal information processing. In particular, dopamine--which has been implicated in the causation of schizophrenia for decades--has been proposed to modulate signal-to-noise ratio. Data are presented which suggest that schizophrenic thought disorder is the result of a hypodopaminergic state and concomitant increased effects of noise in semantic information processing. Possible functions of noise in the nervous systems are discussed.

Computer Simulation↗
PubMed1995

[Alcohol drinking--problems in assessing the public economic impact].

Alcohol consumption is usually regarded as sizeable economic burden to society. Here it is argued that only the external costs of alcohol consumption represent the true costs to society. The methodological and empirical difficulties encountered in assessing these costs may explain the inadequacy of most of the empirical studies available. Therefore, at the moment a valid assessment of the economic burden of alcohol consumption in Germany is not feasible. Anyhow, such an assessment seems to be of questionable value because the actual situation is compared with a hypothetical non-alcohol situation. Therefore, economists should focus on cost-benefit-analysis of real-world policy options.

Alcohol Drinking↗
PubMed1995

Are long-chain polyunsaturated fatty acids essential nutrients in infancy?

We investigated whether the disparity in neural maturation between breastfed and formula-fed term infants could be corrected by the addition of fish oil, a source of docosahexaenoic acid (DHA, 22:6 omega 3), to infant formula. Healthy, term infants were randomised at birth to receive either a supplemented or placebo formula if their mothers had chosen to bottle feed. Breastfed term infants were enrolled as a reference group. Infant erythrocyte fatty acids and anthropometry were assessed on day 5 and at 6, 16, and 30 weeks of age. Visual evoked potential (VEP) acuity was determined at 16 and 30 weeks. VEP acuities of breastfed and supplemented-formula-fed infants were better than those of placebo-formula-fed infants at both 16 and 30 weeks of age (p < 0.001 and p < 0.01). Erythrocyte DHA in breastfed and supplemented-formula-fed infants was maintained near birth levels throughout the 30-week study period but fell in placebo-formula-fed infants (p < 0.001). Erythrocyte DHA was the only fatty acid that consistently correlated with VEP acuity in all infants at both ages tested. A continuous supply of DHA may be required to achieve optimum VEP acuity since infants breastfed for short periods (< 16 weeks) had slower development of VEP than infants receiving a continuous supply of DHA from either breastmilk or supplemented formula. Erythrocyte arachidonic acid (20:4 omega 6) in supplemented-formula-fed infants was reduced below that of infants fed breastmilk or placebo formula at 16 and 30 weeks (p < 0.001), although no adverse effects were noted, with growth of all infants being similar. DHA seems to be an essential nutrient for the optimum neural maturation of term infants as assessed by VEP acuity. Whether supplementation of formula-fed infants with DHA has long-term benefits remains to be elucidated.

Adult↗
PubMed1995

RelA/p65 is a molecular target for the immunosuppressive action of protein kinase A.

Stimulation of the protein kinase A (PKA) signalling pathway exerts an inhibitory effect on the proliferation of numerous cells, including T lymphocytes. In CD4+ T helper cells, stimulation of PKA leads to suppression of interleukin 2 (IL-2) induction, while induction of the genes coding for the lymphokines IL-4 and IL-5 is enhanced. We show that the differential effect of PKA activity on induction of the IL-2 and IL-4 genes is mediated through their promoters. One major target of the suppressive effect of PKA is the kappa B site in the IL-2 promoter. A kappa B site is missing in the IL-4 promoter. Mutations preventing factor binding to the IL-2 kappa B site result in a loss of PKA-mediated suppression of IL-2 promoter activity. Furthermore, activation of the PKA signalling pathway impairs the inducible activity of multiple kappa B sites of the IL-2 promoter, but not of other factor binding sites. The reduction in activity of kappa B sites in activated and PKA-stimulated T cells is accompanied by changes in the concentration and DNA binding of Rel/NF-kappa B factors. Stimulation of the PKA pathway in Jurkat T cells with the PKA activator forskolin leads to an increase in synthesis of c-Rel and p105/p50, while synthesis of p65/RelA remains unchanged. However, nuclear translocation and DNA binding of p65 is distinctly impaired, probably due to a retarded degradation of I kappa B-alpha. In a similar way, stimulation of the PKA signalling pathway inhibits nuclear translocation of p65 and generation of nuclear kappa B complexes in peripheral T lymphocytes from murine lymph nodes. These results indicate that PKA-mediated suppression of NF-kappa B activity plays an important role in the control of activation of peripheral T lymphocytes.

Animals↗
PubMed1995

Enterovirus 71 isolated from China is serologically similar to the prototype E71 BrCr strain but differs in the 5'-noncoding region.

Enterovirus 71 H (E71 H), an isolate from an adult patient with hand-food-mouth disease (HFMD) in China, was serologically similar to the prototype strain E71 BrCr, which was isolated from a patient with aseptic meningitis. The study further analyzed the similarity of E71 H to E71 BrCr at the 5'-noncoding region (NCR), a location in genomic RNA that recently was found to be related to neurovirulence in poliovirus and Venezuelan equine encephalitis virus. Using a reverse transcription-polymerase chain reaction (RT-PCR) technique and a unique primer pair I, a 397 bp product was detected from E71 BrCr, Cox A9 (Griggs), Cox A16 (NIH), Cox B1 (HA antigen 201-468), Cox B5 (wild type), and ECHO 11 (Gregory), but not from E71 H, Cox A24 (Joseph), and ECHO 5 (Noyce). However, all of the viruses generated a 154 bp product using a universal enterovirus primer pair II. Further comparative analysis using primer-directed sequencing of both the E71 H and E71 BrCr 154 bp products revealed that they differed by 12 bases. The variations between the two viruses were clustered in two loci, one in the region of nucleotides 43-61 with eight variations, and the other in the region of nucleotides 120-133 with three variations. The differences within the 5'-NCR between the E71 H (HFMD) and the E71 BrCr (aseptic meningitis) viruses might provide a clue to explain why E71 was associated with two different clinical patterns: polio-like disease in the United States. Australia, and Eastern Europe, HFMD in China, Japan, and Singapore.

Adult↗
PubMed1995

Codon 178 mutation of the human prion protein gene in a German family (Backer family): sequencing data from 72-year-old celloidin-embedded brain tissue.

Familial Creutzfeldt-Jakob disease was first described in a family from northern Germany in the 1920s (Backer family). PCR amplification of DNA extracted from brain tissue embedded in celloidin 72 years ago shows a GAC to AAC substitution at codon 178 of the prion protein gene. This mutation is associated with fatal familial insomnia and familial Creutzfeldt-Jakob disease in a number of families of diverse ethnic background.

Aged↗
PubMed1995

The influence of optimization target selection on the structure of arterial tree models generated by constrained constructive optimization.

The computational method of constrained constructive optimization was used to generate complex arterial model trees by optimization with respect to a target function. Changing the target function also changes the tree structure obtained. For a parameterized family of target functions a series of trees was created, showing visually striking differences in structure that can also be quantified by appropriately chosen numerical indexes. Blood transport path length, pressure profile, and an index for relative segment orientation show clear dependencies on the optimization target, and the nature of changes can be explained on theoretical grounds. The main goal was to display, quantify, and explain the structural changes induced by different optimization target functions.

Animals↗