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At least 451 records · Page 25Linked to original sources
PubMed1998

Determination of muscle contractile properties: the importance of the nerve.

Contractile phenotype of muscle fibres is strongly influenced by hormones, stretch and influences from the motor neurones, although cell lineage probably also plays a role. Motor neurones can affect muscle fibres by releasing neurotrophic substances and by evoking electrical activity in the muscle. For regulating contractile properties such as speed, strength and endurance it has been demonstrated that electrical activity is crucial, while the role of putative neurotrophic substances remains unclear. The signal to change is coded in the pattern of electrical activity. Thus, high amounts of activity lead to slow shortening velocity and myosin heavy chains, while low amounts of activity lead to a fast phenotype. For regulation of twitch duration frequency also plays a role, and for preventing atrophy in denervated muscles high frequency seems to be beneficial, particularly in fast muscles. Little is known about the excitation-adaptation pathway linking action potentials to expression of genes that are relevant for contractile properties. Muscle specific transcription factors of the helix-loop-helix family such as myoD and myogenin could be important for regulating genes related to metabolic profile and fibre size/strength, while their role in determining myosin heavy chain expression and classical fibre type is more uncertain.

Humans↗
PubMed2000

Identification and characterization of a new allele for the beta subunit of follicle-stimulating hormone in Chinese pig breeds.

During evaluation of follicle-stimulating hormone-beta (FSHB) expression in anterior pituitary glands by an RNase protection assay (RPA), the expected fragment of 205 nucleotides at positions 759-963 was not detected in one boar that had moderate plasma and pituitary FSH concentrations. After subcloning and sequencing, mRNA from this boar lacked an 11-bp fragment (5'-CATTTGGAAAC-3') at nucleotide positions 807-817 of the 3'-untranslated region (3'-UTR, D allele). Wild-type FSHB (WT allele) was present in pituitary RNA and genomic DNA in both Meishan (MS) and White Composite (WC) pigs; whereas the D allele was present only in MS pigs (P < 0.01; 5/6 MS vs. 0/6 WC). Also, we found the D allele in five other Chinese breeds but absent in ten American Landrace, 11 Yorkshire and 17 Berkshire pigs. Additionally, the D allele had one silent nucleotide change in the coding region plus six, single nucleotide changes in the 3'-UTR.

3' Untranslated Regions↗
PubMed2003

A double-screening method to identify reliable candidate non-synonymous SNPs from chicken EST data.

Discovery of non-synonymous single nucleotide polymorphisms (nsSNP), which cause amino acid substitutions, is important because they are more likely to alter protein function than synonymous SNPs (sSNP) or those SNPs that do not result in amino acid changes. By changing the coding sequences, nsSNP may play a role in heritable differences between individual organisms. In the chicken and many other vertebrates, the main obstacle for identifying nsSNP is that there is insufficient protein and mRNA sequence information for self-species referencing and thus, determination of the correct reading frame for expressed sequence tags (ESTs) is difficult. Therefore, in order to estimate the correct reading frame at nsSNP in chicken ESTs, a double-screening approach was designed using self- or cross-species protein referencing, in addition to the ESTScan coding region estimation programme. Starting with 23 427 chicken ESTs, 1210 potential SNPs were discovered using a phred/phrap/polyphred/consed pipeline process and among these, 108 candidate nsSNP were identified with the double screening method. A searchable SNP database (chicksnps) for the candidate chicken SNPs, including both nsSNPs and sSNPs is available at http://chicksnps.afs.udel.edu. The chicken SNP data described in this paper have been submitted to the data base SNP under National Center for Biotechnology Information assay ID ss4387050-ss4388259.

Animals↗
PubMedDate not supplied

Does cortical motion adaptation exhibit functional properties analogous to light adaptation in the retina?

PURPOSE: The retina codes variations in luminance by adapting to and hence discounting, the mean luminance. During adaptation to a moving pattern, perceived speed decreases. Thus we know that the adapted visual system does not simply code the absolute speed of a stimulus. We hypothesize that adaptation to a moving stimulus serves to optimize coding of changes in speed at the expense of maintaining an accurate representation of absolute speed. In this case we would expect discrimination of speeds around the adapted level to be preserved or enhanced by motion adaptation. METHODS AND RESULTS: After adaptation to motion in the same direction as a subsequent test stimulus, seven of eight subjects showed a reduction of perceived speed in the adapted region and seven showed enhanced discrimination. CONCLUSIONS: We conclude that motion adaptation preserves or enhances differential speed sensitivity at the expense of an accurate representation of absolute speed in a manner analogous to retinal light adaptation.

Adaptation, Ocular↗
PubMed1999

Rapid and simple determination of hereditary haemochromatosis mutations by multiplex PCR-SSCP: detection of a new polymorphic mutation.

Hereditary haemochromatosis is a common inherited disorder leading to excessive accumulation of iron in various organs. Two missense substitutions at the HFE-gene have recently been associated with the disease, 187C G and 845G-->A (mutations H63D and C282Y, respectively). We present a simple, rapid PCR-SSCP multiplex screening method allowing the simultaneous detection of both substitutions. Furthermore, testing the method on 420 Danish blood donors revealed the presence of a hitherto undetected third substitution in 13 individuals. The new substitution, a 193A-->T transversion, affects codon 65 changing the code for serine to that of cysteine (S65C). It may thus have functional consequences for the HLA class protein encoded by the HFE-gene. The allele frequencies observed were: H63D 14.8%, C282Y 6.2% and S65C 1.5%, which for the two former alleles are in agreement with frequencies reported for other North European population samples.

Adolescent↗
PubMedDate not supplied

Prenatal exclusion of Ehlers-Danlos syndrome type VI by mutational analysis.

We have performed the first prenatal assessment of clinical phenotype in a family affected by Ehlers-Danlos syndrome type VI (EDS VI), an inherited collagen disorder, by screening the fetal DNA for mutations in the lysyl hydroxylase (LH) gene. We have previously reported that the affected child in this family is compound heterozygous for mutations in the LH gene. One allele has a paternally inherited C1557 to G change that codes for a premature stop codon (Y511X) in exon 14 and the other allele has a deletion of exon 5 that results from a maternally inherited mutation in the consensus donor splice site of intron 5. To perform the prenatal diagnosis, we sequenced genomic DNA isolated from cultured chorionic villus cells at 10 weeks of gestation. One allele had the maternally inherited gt --> at splice-site mutation in exon 5, and the other paternally inherited allele was normal. As EDS VI is a recessive disorder, we predicted that although a carrier, the baby should be unaffected. This conclusion, which was supported by a normal level of LH activity in the chorionic villus cells, was confirmed by the birth of a healthy unaffected baby.

Alleles↗
PubMed1996

Casemix funding in psychiatry: some problems and common pitfalls.

The aims of this study were to evaluate the accuracy of AN-DRG version 2.0 codings. Ninety-two separations, covering three of the most commonly occurring AN-DRG in psychiatry, were reviewed by a psychiatrist. The AN-DRG diagnosis was then compared to that given by morbidity coders. There was agreement for 69 (79 per cent) separations and disagreement for 18 (21 per cent) separations. Recoding of the 18 separations altered average length of stay data and the funding received. The high error rate of coding stimulated changes to the training of morbidity coders and registrars.

Abstracting and Indexing↗
PubMed2003

Adaptive evolution in the Arabidopsis MADS-box gene family inferred from its complete resolved phylogeny.

Gene duplication is a substrate of evolution. However, the relative importance of positive selection versus relaxation of constraints in the functional divergence of gene copies is still under debate. Plant MADS-box genes encode transcriptional regulators key in various aspects of development and have undergone extensive duplications to form a large family. We recovered 104 MADS sequences from the Arabidopsis genome. Bayesian phylogenetic trees recover type II lineage as a monophyletic group and resolve a branching sequence of monophyletic groups within this lineage. The type I lineage is comprised of several divergent groups. However, contrasting gene structure and patterns of chromosomal distribution between type I and II sequences suggest that they had different evolutionary histories and support the placement of the root of the gene family between these two groups. Site-specific and site-branch analyses of positive Darwinian selection (PDS) suggest that different selection regimes could have affected the evolution of these lineages. We found evidence for PDS along the branch leading to flowering time genes that have a direct impact on plant fitness. Sites with high probabilities of having been under PDS were found in the MADS and K domains, suggesting that these played important roles in the acquisition of novel functions during MADS-box diversification. Detected sites are targets for further experimental analyses. We argue that adaptive changes in MADS-domain protein sequences have been important for their functional divergence, suggesting that changes within coding regions of transcriptional regulators have influenced phenotypic evolution of plants.

Arabidopsis↗
PubMed1992

Evolution of the mouse t haplotype: recent and worldwide introgression to Mus musculus.

Mouse t haplotypes are variants of chromosome 17, consisting of four inversions. Despite the homozygous lethality and pleiotropic effect on embryonic development, sperm production, and recombination, they have widely spread in natural populations of the house mouse (10-40% in frequency) because of the meiotic drive advantage. We sequenced 14 Tcp-1 (t-complex polypeptide 1) genes from four t haplotypes, nine wild mice, and a rat as a reference. From a comparison of intron sequences of 610 base pairs, we dated the origin of t haplotypes to 2.9 +/- 0.7 million years ago, which predates the splitting of Mus musculus subspecies (approximately 1 million years ago). However, the Tcp-1 intron sequences of t haplotypes from different M. musculus subspecies from various parts of the world show no divergence, indicating the recent introgression (no earlier than 0.8 million years ago) of a single ancestral type. Nucleotide changes in coding regions are also consistent with this conclusion. Hence, polymorphisms among t haplotypes including lethality factors have accumulated during this short time period independently in each M. musculus subspecies.

Animals↗
PubMed2005

WNK1 activates SGK1 by a phosphatidylinositol 3-kinase-dependent and non-catalytic mechanism.

WNK1 (with no lysine (K) 1) is a protein-serine/threonine kinase with a unique catalytic site organization. Deletions in the first intron of the WNK1 gene were found in a group of hypertensive patients with pseudohypoaldosteronism type II. No changes in coding sequence of WNK1 were found, but its expression was increased severalfold. We have been investigating actions of WNK1 and have found that WNK1 activates the serum- and glucocorticoid-induced protein kinase SGK1, which impacts membrane expression of the epithelial sodium channel. Here we explore the role of WNK1 in SGK1 regulation. Activation of SGK1 by WNK1 is blocked by phosphatidylinositol 3-kinase inhibitors. Neither the catalytic activity nor the kinase domain of WNK1 is required; rather the N-terminal 220 residues of WNK1 are necessary and sufficient to activate SGK1. Phosphorylation of WNK1 on Thr-58 contributes to SGK1 activation. Finally, we show that WNK1 is required for the activation of SGK1 by insulin-like growth factor 1.

Animals↗
PubMed2005

Heterozygous mutations of OTX2 cause severe ocular malformations.

Major malformations of the human eye, including microphthalmia and anophthalmia, are examples of phenotypes that recur in families yet often show no clear Mendelian inheritance pattern. Defining loci by mapping is therefore rarely feasible. Using a candidate-gene approach, we have identified heterozygous coding-region changes in the homeobox gene OTX2 in eight families with ocular malformations. The expression pattern of OTX2 in human embryos is consistent with the eye phenotypes observed in the patients, which range from bilateral anophthalmia to retinal defects resembling Leber congenital amaurosis and pigmentary retinopathy. Magnetic resonance imaging scans revealed defects of the optic nerve, optic chiasm, and, in some cases, brain. In two families, the mutations appear to have occurred de novo in severely affected offspring, and, in two other families, the mutations have been inherited from a gonosomal mosaic parent. Data from these four families support a simple model in which OTX2 heterozygous loss-of-function mutations cause ocular malformations. Four additional families display complex inheritance patterns, suggesting that OTX2 mutations alone may not lead to consistent phenotypes. The high incidence of mosaicism and the reduced penetrance have implications for genetic counseling.

Amino Acid Motifs↗
PubMed2000

IFN-alpha1a gene is the major variant in the North American population.

Thirteen interferon (IFN)-alpha functional genes have been reported. A number of these genes have allelic members (variants). In the case of IFN-alpha1, two variants, IFN-alpha1a and IFN-alpha1b, are known. The variants differ from each other by one base change in the coding region, leading to a single change in amino acid sequence and the presence of a restriction site. We have developed oligonucleotide primers for amplification of IFN-alpha1 gene(s) using polymerase chain reaction (PCR). Genomic DNA, obtained from over 23,000 normal healthy individuals and from four human cell lines, were used as templates in PCR to amplify the IFN-alpha1 gene sequences. The resulting PCR products were analyzed by restriction endonuclease digestion and DNA sequencing to identify the presence of variant sequences. The results show that IFN-alpha1a is predominant in the genomic DNA of the population examined. Among the cell lines studied, IFN-alpha1a is the only variant found in U-937 and Namalwa cells, whereas KG-1 cells have only IFN-alpha1b, and EB-3 cells have both IFN-alpha1a and IFN-alpha1b in the genome.

Alleles↗
PubMed2001

RNAi is antagonized by A-->I hyper-editing.

RNA interference (RNAi) and adenosine to inosine conversion are both mechanisms that respond to double-stranded RNA (dsRNA) and have been suggested to have antiviral roles. RNAi involves processing of dsRNA to short interfering RNAs (siRNAs), which subsequently mediate degradation of the cognate mRNAs. Deamination of adenosines changes the coding capacity of the RNA, as inosine is decoded as guanosine, and alters the structure because A-U base pairs are replaced by I*U wobble pairs. Here we show that RNAi is inhibited if the triggering dsRNA is first deaminated by ADAR2. Moreover, we show that production of siRNAs is progressively inhibited with increasing deamination and that this is sufficient to explain the inhibition of RNAi upon hyper-editing of dsRNAs.

Adenosine↗
PubMed1989

The changing pattern of coronary heart disease in Australia.

In this paper we describe a method for constructing long series of comparable mortality statistics from published figures that are subject to periodic changes in coding practice. The case discussed in some detail is that of Australian coronary heart disease mortality 1931-1985, the coding of which has been liable to alteration on four occasions due to revisions to the procedures of the International Classification of Diseases. Reference is made to comparable work on US figures and it is shown that the Australian data require relatively smaller adjustments.

Adult↗
PubMed1999

Artefactual increasing frequency of omphaloceles in the Northern Netherlands: lessons for systematic analysis of apparent epidemics.

BACKGROUND: While monitoring birth defects in a registry, statistically significant increases in prevalence occasionally occur. In the European Registration Of Congenital Anomalies (EUROCAT) in the Northern Netherlands 20000 births are monitored every year. For omphaloceles, a steady increase in the prevalence from 0.86 per 10000 live- and stillbirths in 1981-1983 to 3.11 per 10000 live- and stillbirths in 1994 was seen in the three northern provinces of The Netherlands. METHODS: A stepwise enquiry into this increase, which included checking for misclassification and change in coding and ascertainment when necessary, was done. All cases of omphalocele and associated or similar birth defects registered at the EUROCAT registry were retrieved and if necessary recoded. RESULTS: This study showed that the increase reported previously was not a true time trend. A few cases of e.g. diastasis recti and trisomy 18 were misclassified. The prevalence in more recent years is comparable with that in the rest of Europe, whereas it used to be lower. There was an increase in isolated omphalocele, but the numbers are small. CONCLUSIONS: The stepwise enquiry described should be a standard procedure after noticing an increasing prevalence in a registry. A better subdivision, e.g. in isolated cases versus children with multiple congenital anomalies, before monitoring can contribute to a lower number of false positive signals.

Congenital Abnormalities↗
PubMed1992

Postnatal shift of tonotopic organization in the chick auditory cortex analogue.

The existence of an ontogenetic shift of tonotopic organization throughout the auditory pathway concomitant with cochlea maturation is a matter of controversy. Using the 2-deoxyglucose method we demonstrate here for the first time the shift phenomenon in an auditory forebrain structure, field L, the auditory cortex analogue of the chick. During the first postnatal month isofrequency contours move to positions where, in younger chicks, lower frequencies (up to half an octave) are represented. This developmentally changing place code of sound frequencies at the forebrain level is similar to the one previously reported for brain stem auditory nuclei. It raises the question of constancy of frequency-related pitch perception during development and may be a complication of early auditory learning and memory.

Acoustic Stimulation↗
PubMed2002

Continuous potential display of ictal electrocorticography.

The objective of this study was to determine whether the animation of electrical activity recorded on ictal electrocorticograms (ECoGs) can demonstrate the propagation of seizure discharges from the epileptogenic zone (EZ) to the surrounding cortical area. A computer program, continuous potential display (CPD), was designed to animate the color-coded potential changes in 5-msec intervals at each recorded site. This program was used to analyze 35 ictal ECoGs recorded by subdural grid electrodes from 11 subjects who underwent epilepsy surgery for intractable partial seizures. Continuous potential display demonstrated recurrent cycles of seizure propagation from the EZ to the surrounding cortical area even when seizure discharges appeared widespread on ECoG. Hence, the EZ could be mapped at any time during the seizure course. The EZ mapped by analyzing a small fraction of ECoG during widespread seizure discharges using CPD only overlapped 69 +/- 24% (mean +/- standard deviation) of the surgical area. The EZ mapped by CPD had 34 +/- 22% false positives and 35 +/- 27% false negatives. Animation of potential changes recorded by ictal ECoG can assist in studying the temporal and spatial patterns of seizure propagation and in mapping the EZ for surgical resection.

Action Potentials↗