Unknown peptide sequencing using matrix-assisted laser desorption/ionization and in-source decay

The results of a study to determine the utility of in-source decay fragmentation of matrix-assisted laser-desorbed ions for obtaining useful sequence information on unknown peptides are presented. Six peptides were purified by high-performance liquid chromatography and submitted as single blind unknowns. The in-source decay fragment ion data were collected on a linear time-of-flight mass spectrometer equipped with delayed extraction. These fragment ion data were manually interpreted on the basis of known fragmentation pathways to determine a proposed sequence. The proposed sequences for three of the unknowns were essentially correct, with a few minor errors. A fourth unknown had significant errors associated with its proposed sequence due to misinterpretation of the fragmentation data. Two unknowns were found to have undergone significant sample degradation prior to analysis, which compromised the results for these samples. An example of the use of protein database searching of a partial peptide sequence to aid in a sequence determination is also presented.

Acute regulation of glucose uptake in cardiac muscle of the American eel Anguilla rostrata

We investigated the effects of anoxia and contractile activity on glucose uptake and the intracellular location of hexokinase in cardiac muscle of the American eel Anguilla rostrata. Uptake of 2-deoxyglucose (2-DG) by ventricle strips at 15 °C was increased by 45 % by anoxia and by 85 % by contractile activity over basal conditions. The anoxia- and contraction-induced increase in basal 2-DG uptake was inhibited completely by 25 µmol l-1 cytochalasin B, suggesting that facilitated glucose transporters are involved. Maximal activity of hexokinase in whole homogenates (approximately 10 µmol min-1 g-1 tissue) was 200 times higher than the maximal rate of 2-DG uptake measured in vitro (46 nmol min-1 g-1 tissue). Only 20­25 % of hexokinase activity was localized to the mitochondrial fraction, and this was not altered by perfusion of the hearts with anoxic media. It is therefore unlikely that anoxia-induced stimulation of 2-DG uptake is mediated by intracellular translocation of hexokinase. As in the case of mammalian muscle, glucose 6-phosphate is a potent inhibitor of hexokinase in eel cardiac muscle (IC50=0.44 mmol l-1). In summary, anoxia and contractile activity significantly increase 2-DG uptake in cardiac muscle of American eels, and glucose transport may be rate-limiting for glucose utilization. Increased utilization of glucose during anoxia or contractile activity may involve the recruitment of facilitative glucose transport proteins to the cell surface of myocytes or an increase in the intrinsic activity of glucose transporters already residing at the cell surface.

Imagery of craving in opiate addicts undergoing detoxification

Craving is a significant factor in opiate addiction that is associated with drug-dependence and in relapse to drug use after treatment. In order to better understand the psychological and physiological mechanisms of craving for opiates, we have developed an imagery-based procedure using personal verbal descriptions of craving in abstinent opiate addicts. Thirteen opiate addicts in detoxification were required to imagine and describe their craving experiences while autonomic measures of heart rate and arterial pressure were taken. Subjects displayed a significant increase in systolic blood pressure and heart rate while describing drug craving compared with neutral descriptions. Furthermore, an increase in systolic blood pressure during imagery of craving descriptions compared with neutral descriptions was observed. These results provide preliminary evidence that imagery is powerful in eliciting craving for opiates, as indicated by subjective ratings and autonomic measures. The implications of the results of this paper for the cue-exposure paradigm and contemporary models of addiction are being discussed.

RIGUI, a putative mammalian ortholog of the Drosophila period gene

The molecular components of mammalian circadian clocks are elusive. We have isolated a human gene termed RIGUI that encodes a bHLH/PAS protein 44% homologous to Drosophila period. The highly conserved mouse homolog (m-rigui) is expressed in a circadian pattern in the suprachiasmatic nucleus (SCN), the master regulator of circadian clocks in mammals. Circadian expression in the SCN continues in constant darkness, and a shift in the light/dark cycle evokes a proportional shift of m-rigui expression in the SCN. m-rigui transcripts also appear in a periodic pattern in Purkinje neurons, pars tuberalis, and retina, but with a timing of oscillation different from that seen in the SCN. Sequence homology and circadian patterns of expression suggest that RIGUI is a mammalian ortholog of the Drosophila period gene, raising the possibility that a regulator of circadian clocks is conserved.

Flumazenil in alcohol withdrawal: a double-blind placebo-controlled study

The purpose of the present study was to study gamma-aminobutyric acid (GABA)-A receptor function in alcohol-dependent subjects during withdrawal, using the benzodiazepine antagonist flumazenil. In particular, we wanted to examine the hypotheses that an endogenous inverse agonist ligand at the GABA-A benzodiazepine receptor (GBzR) is active during withdrawal (in which case flumazenil should be anxiolytic), or whether chronic alcohol intake results in a shift in sensitivity of the receptor in the inverse agonist direction (in which case flumazenil should be anxiogenic). Results from 15 alcohol-dependent subjects in a double-blind placebo-controlled cross-over study showed that flumazenil was neither anxiolytic nor anxiogenic, although withdrawal scores were reduced during the course of the study. The fact that flumazenil was not anxiogenic, as it is in panic disorder, suggests that the GBzR is functioning differently in these two clinically similar conditions.

An MRI study of autism: the cerebellum revisited

We addressed the controversies surrounding the size of the neocerebellar vermis in autism and examined cerebellar size in light of recent reports of enlarged brain size in this disorder. In this study we use detailed MRI (1.5 mm) to examine the area of cerebellar lobules I through V and VI and VII and the volume of the total cerebellum in 35 autistic subjects and 36 controls. No abnormalities in the size of cerebellar lobules VI and VII in autistic individuals were detected, but the volume of the total cerebellum was significantly increased. We conclude that selective neocerebellar size abnormalities are not present in autistic individuals. Enlarged total cerebellar volume detected in this study is consistent with previous reports of regional brain enlargement in autism and also consistent with theories hypothesizing that the primary defect in autism is the result of abnormal development of a distributed neural network involving a number of regions of the brain.

An MRI study of the corpus callosum in autism

OBJECTIVE

The purpose of this study was to examine the size of subregions of the corpus callosum in autistic individuals.

METHOD

The areas of three subregions (anterior, body, and posterior) of the corpus callosum were examined on midsagittal magnetic resonance images of 35 autistic subjects whose mean age was 18 years and 36 healthy comparison subjects matched on age and IQ.

RESULTS

After controlling for total brain volume, gender, and performance IQ, the authors detected a significantly smaller size of the body and posterior subregions of the corpus callosum in the autistic individuals.

CONCLUSIONS

In the context of recent reports of increased brain size in autism, several possible mechanisms are considered in exploring the significance of a smaller relative size of the corpus callosum in autism.

Molecular cloning, over-expression, developmental regulation and immunolocalization of fragminP, a gelsolin-related actin-binding protein from Physarum polycephalum plasmodia

FragminP is a Ca2+-dependent actin-binding and microfilament regulatory protein of the gelsolin family. We screened a Physarum polycephalum cDNA library with polyclonal fragminP antibodies and isolated a cDNA clone of 1,104 bp encoding 368 amino acids of fragminP, revealing two consensus phosphatidylinositol 4,5 bisphosphate-binding motifs in the central part of the protein. The first methionine is modified by an acetyl group, and three amino acids were missing from the protein coded for by the cDNA clone. Full-length recombinant fragminP was generated by PCR, purified after over-expression from Escherichia coli and displayed identical properties to native Physarum fragminP. Northern blot analysis against RNA, isolated from cultures at various stages of development, indicated that fragminP is absent from amoebae and that expression is initiated at an early stage during apogamic development, in a similar way to that observed for the profilin genes. In situ immunolocalization of fragminP in Physarum microplasmodia revealed that the protein is localized predominantly at the plasma membrane, suggesting a role in the regulation of the subcortical actin meshwork. Our data indicate that we have isolated the plasmodium-specific fragminP cDNA (frgP) and suggest that, in each of its two vegetative cell types, P. polycephalum uses a different fragmin isoform that performs different functions.

Environmental Impact Assessment and Management: An UnderexploredRelationship

/ Some 25 years of environmental impact assessment (EIA) practicehas seen the development of a wealth of experience. The bulk of our exposureto EIA exists in the form of actual practice, perhaps recorded as publishedcase studies. There also exists a substantial literature reporting theresults of empirical and theoretical research. In this paper a perceiveddeficiency in the theoretical literature is identified. This deficiency liesin the exploration of the relationship between EIA and subsequentenvironmental management.In this paper the existing body of theory is reviewed to highlight the needfor further attention to be paid to the EIA/management relationship. Inparticular it is shown that the majority of the literature to date hasconcentrated on the influence of EIA leading up to and including the decisionto proceed or not with the proposed action. Less attention has been paid tothe extension of the influence of EIA beyond this point to inform the processof ongoing environmental management.This relationship is then explored by reference to the Western Australian EIAsystem. One of the strengths of this system is its focus upon theimplementation and management of proposed developments. The outcome of EIA isgenerally an approval to proceed with the development subject to meeting asuite of environmental design and management objectives.KEY WORDS: Environmental impact assessment; Ongoing management

A simple screen for permissive sites in proteins: analysis of Escherichia coli lac permease

Proteins can be remarkably tolerant of major mutational changes. Sites that accomodate large insertions without loss of function ("permissive" sites) appear generally to correspond to surface regions at which the added sequences do not disrupt overall folding. The identification of such sites can aid in the engineering of functional derivatives of a protein with novel properties. To screen for permissive sites, we developed a simple two-step procedure for generating 31-codon insertions in cloned genes. In a first step, a beta-galactosidase or alkaline phosphatase gene fusion is generated by insertion of a transposon derivative into the target gene. Requiring beta-galactosidase or alkaline phosphatase activity fixes the translational reading frame of the transposon relative to the target gene. In a second step, most of the transposon sequences are excised in vitro, leaving the in-frame insertion. Insertions may be targeted either to cytoplasmic or exported protein sequences, and the inserted sequence acts as an epitope in a variety of proteins. As a test case, a set of 31-codon insertions in the Escherichia coli lac permease gene was generated. The lactose transport activities of the mutant proteins followed a simple pattern: most of the proteins (10/12) with insertions in sequences thought to face the cytoplasm or periplasm were at least partially active, whereas all proteins (9/9) with insertions in membrane-spanning sequences were inactive. The only exceptions were two inactive proteins with insertions in the third cytoplasmic region. Most of the inactive proteins were detected at reduced levels in cells, presumably due to proteolytic breakdown. These studies thus illustrate the use of the new method to identify permissive sites and help document the remarkable sequence flexibility of many of the hydrophilic loops in lac permease. In addition to screening for permissive sites, 31-codon insertion mutagenesis may be useful in epitope-tagging proteins at multiple internal positions, in analyzing membrane protein topology, and in dissecting structure-function relationships in proteins.

Autosomal dominant cerebellar ataxia (SCA6) associated with small polyglutamine expansions in the alpha 1A-voltage-dependent calcium channel

A polymorphic CAG repeat was identified in the human alpha 1A voltage-dependent calcium channel subunit. To test the hypothesis that expansion of this CAG repeat could be the cause of an inherited progressive ataxia, we genotyped a large number of unrelated controls and ataxia patients. Eight unrelated patients with late onset ataxia had alleles with larger repeat numbers (21-27) compared to the number of repeats (4-16) in 475 non-ataxia individuals. Analysis of the repeat length in families of the affected individuals revealed that the expansion segregated with the phenotype in every patient. We identified six isoforms of the human alpha 1A calcium channel subunit. The CAG repeat is within the open reading frame and is predicted to encode glutamine in three of the isoforms. We conclude that a small polyglutamine expansion in the human alpha 1A calcium channel is most likely the cause of a newly classified autosomal dominant spinocerebellar ataxia, SCA6.

Isolation, mapping, and genomic structure of an X-linked gene for a subunit of human mitochondrial complex I

We report here the isolation, mapping, and genomic organization of the human NDUFA1 gene, which is a component of NADH:ubiquinone oxidoreductase (complex I). The NDUFA1 cDNA clone and associated genomic cosmid clones were isolated by reciprocal probing of an arrayed human heart cDNA library with a X-chromosome cosmid library and were mapped to Xq24. The NDUFA1 gene, which is highly expressed in human cardiac and skeletal muscle, has an open reading frame of 70 amino acids and shows 80% homology to the bovine MWFE subunit of complex I. By primer extension, the major and minor transcription initiation sites were identified, 99 and 141 nucleotides upstream of the translation initiator ATG, respectively. The NDUFA1 gene is composed of 3 exons and spans about 5.0 kb of genomic DNA. The 5' region of the NDUFA1 gene (approximately 450-bp fragment) lacks conventional TATA and CAAT boxes, but it contains several potential binding sites for transcription factors including SP-1, AP-2, NF1, NRF2-like, APRRE, CRE, MyoD1, CArG, MEF-2, and BRE.

Using nursing theory to introduce change in practice

This article outlines the theoretical basis of nursing using Carper's (1978) fundamental patterns of knowing and explains how this theory can be integrated with practice. The authors also describe how Carper's theory was used to introduce change related to the reduction in junior doctors' hours through the development, implementation and evaluation of nurse practitioners. Using a SWOT analysis exercise and various workshops, practitioners have been able to develop professionally and integrate the art and science of nursing.

Molecular dissection of a cosmid from a gene-rich region in 17q21 and characterization of a candidate gene for alpha-N-acetylglucosaminidase with two cDNA isoforms

A cosmid mapped to human Chromosome (Chr) 17q21, c140c10, was found to contain a CpG island. We completed the sequence analysis of c140c10 because of two considerations: the cosmid contained an STS from the 17-beta-hydroxysteroid dehydrogenase gene (17-HSD), which was believed to be a neighbor of the breast cancer susceptibility gene, BRCA1; CpG islands are usually associated downstream and/or upstream of human genes. Computer-based exon trapping of the cosmid sequence revealed putative additional exons. With two of those exons used as a probe to screen human placental cDNA libraries, two cDNA isoforms for a novel gene, designated as ufHSD, were isolated. The amino acid sequence of the open reading frames of the cDNA showed no significant homology to any protein in the data base. However, it is possible that our cDNAs are from the gene for alpha-acetylglucosaminidase, which has recently been localized to the same region. Northern analyses show that the major isoform is expressed in all tissues tested, with the highest expression in blood leukocytes and lowest in brain. Finally, our study has shown that the 46.7-kb cosmid c140c10 encompasses loci for five genes and pseudo-genes: PsiPTP4A, ufHSD, 17-HSDI, 17-HSDII, and 22A1.

Characterization and genomic mapping of genes and pseudogenes of a new human protein tyrosine phosphatase

Previously described protein tyrosine phosphatases (PTPs) are classified into three types according to their sequence homology and structural features. Here we describe the characterization of genes and pseudogenes of a member of a fourth type of PTP, designated protein tyrosine phosphatase 4A (PTP4A). The 167-amino-acid human PTP4A bears the signature active site of all PTPs, but does not show any other sequence homology to any of the previously described PTPs. Two cDNAs encoding PTP4A that differed in their noncoding regions were isolated. Another cDNA that has a high level of sequence identity with these two cDNAs and a deletion in the coding region was also isolated. Northern analysis using a probe from a common 3'-untranslated region of the cDNAs recognized mRNAs of about 2 and 4 kb. Both species of mRNA were seen in all human adult and fetal tissues tested. Fluorescence in situ hybridization mapping of the corresponding yeast artificial chromosome clones and sequence-tagged site analysis suggested that one of the PTP4A coding genes is located at 1p35 and the other is on chromosome 11. A processed pseudogene for PTP4A was found in the BRCA1 region of 17q21 and shares 96% sequence identity to one of the PTP4A coding cDNAs. Our studies also suggest the existence of another processed pseudogene on chromosome 11.

Transactional analysis: how to improve communication skills

Transactional analysis (TA) can be a useful framework for promoting effective communication. This article outlines the theoretical constructs of TA and suggests a strategy for teaching the model to diploma student nurses. The authors argue that an understanding of TA will allow nurses to analyse and adjust their skills to communicate more effectively.

Regional brain enlargement in autism: a magnetic resonance imaging study

OBJECTIVE

To determine whether increased brain volume in autism, suggested in previous studies, is the result of general or regional brain size differences and to study the effect of gender on brain size and pattern of enlargement.

METHOD

Total brain volume and cerebral cortical lobe volumes were examined in 35 autistic and 36 comparison subjects using magnetic resonance imaging and an automated method of brain volume measurement.

RESULTS

After controlling for height and nonverbal IQ, the authors detected a significant diagnosis x gender effect (F = 7.4; p = .009) for total brain volume. A repeated-measures analysis of variance indicated that the pattern of enlargement (brain region x diagnosis) in autistic subjects differed from that in controls (F = 4.88; p = .0004). Subsequent sex-specific analysis revealed significantly increased total brain volume in autistic males but not females. Analysis of lobe sizes showed significant enlargement in autistic subjects in temporal, parietal, and occipital, but not frontal lobes.

CONCLUSIONS

These results suggest that brain size is increased in autism and that differences are not generalized but appear to be the result of a pattern of enlargement with increases in the size of specific cortical lobes.

Neural isolation of the jejunoileum. Effect on tissue morphometry, mucosal disaccharidase activity, and tissue peptide content

The aim of this study was to determine the effects of a model of intestinal extrinsic denervation on mucosal structure and function. Six dogs underwent in situ neural isolation of the jejunoileum (Group 2); six other dogs served as operated controls (Group 1), and five nonoperated dogs were naive controls (Group 3). Thirty-centimeter segments of proximal jejunum and distal ileum were excised before (time zero) and at 2 weeks and 8 weeks postoperatively in Groups 1 and 2, while similar regions were removed at time zero in Group 3. Tissues were analyzed for morphology with quantitative morphometry, mucosal disaccharidase activities (sucrase, maltase, and lactase), and tissue content of selected regulatory peptides in transmural, mucosa/submucosa, and muscularis regions. In situ neural isolation had no significant or consistent effects on morphology/morphometry or on mucosal disaccharidase activities. Tissue content of neuropeptide Y decreased markedly (P < 0.002) in all layers of the jejunal and ileal walls, but tissue content of vasoactive inhibitory polypeptide, substance P, cholecystokinin, neurotensin, met-enkephalin, neurokinin A, somatostatin, and calcitonin gene-related peptide demonstrated only minor changes. The physiologic effects of intestinal transplantation (extrinsic denervation and disruption of intrinsic, enteric neural continuity, and lymphatic drainage) have little effect on morphology, mucosal disaccharidase activity, and tissue content of most regulatory peptides. How these minor alterations might affect enteric function, however, needs to be investigated.

The psychoeducational profile of boys with Klinefelter syndrome

Klinefelter syndrome (KS) affects about 1 in 900 males due to an extra X chromosome. Although there are no obvious physical features associated with childhood KS, many boys demonstrate a cognitive deficit in verbal processing. The first section of this article integrates the extant literature on intelligence and achievement outcomes in boys with KS. The second section presents our findings from a 20-year study involving one of the largest unselected cohorts of boys with KS. We followed 36 boys with KS and 33 sibling controls from 6 until 20 years of age. Boys with KS are shown to demonstrate a verbal cognitive deficit and significant underachievement in reading and spelling, as well as in arithmetic. These problems, which are evident from early school years, increase with age such that by late adolescence, boys with KS are four to five grade levels behind. In addition, we also found that they were most likely to have a generalized type of learning disability, with very few boys indicating a pure reading or pure arithmetic problem. They also showed deficits in written language skills and acquisition of knowledge-based subject material were also problematic. Despite significant underachievement and frequent grade failure, many boys with KS had completed high school, and a few were also pursuing postsecondary educations. The discussion section examines how their language-based disability affects comprehension and learning, leading to underachievement.

Sedative antidepressants impair visual detection mechanisms in humans

The safety of sedative antidepressants is a topical issue in the treatment of depression, with driving impairment being of particular concern. We have recently completed a study with normal male volunteers comparing the actions of dothiepin (a traditional, sedating antidepressant) with those of fluvoxamine (one of the selective serotonin re-uptake-inhibiting SSRI class of newer antidepressants) on psychomotor functions relevant to driving. We set out to investigate whether these drugs impair visual selective attention (focused and divided) by employing the 'odd-ball' task. Subjects were required to respond to letters of the alphabet (T for target and other letters for non-targets) that were presented at the centre and/or periphery of the computer screen. The task has been shown to be useful in detecting differences between drugs in their effects on selective attention. Preliminary results show that dothiepin delayed responses to single targets compared with fluvoxamine and placebo. There was also preliminary evidence that it mainly affected response times to peripheral targets. Furthermore, there was preliminary evidence that both drugs delayed responses to central targets compared with placebo on the divided attention trials. Finally, response accuracy in detecting peripheral targets was greater under placebo compared with fluvoxamine and dothiepin. The impairment produced by dothiepin is presumably a consequence of the central blockade of cholinergic muscarinic or histaminergic H1 receptors. It could contribute to the reported association between the tricyclic class of antidepressants and road traffic accidents, and would be worth further investigation in depressed patients taking both classes of drug.

Intelligence and achievement in children with extra X aneuploidy: a longitudinal perspective

Forty-seven children (35 male, 12 female) identified as having a supernumerary X chromosome by neonatal screening were studied psychologically from childhood to late adolescence. This paper compares their findings relative to sibling controls on tests of intelligence and achievement collected over a 14-year period. Children with a supernumerary X chromosome were found to score consistently below controls on Verbal IQ and subtests comprising the Verbal Comprehension factor but they did not differ on Performance IQ, which was in the normal range. At all ages, they showed poorer reading and arithmetic achievement; relative risk for reading and arithmetic impairment was 2.6 and 2.6 in males and 1.1 and 1.7 in females. Males with an extra X chromosome were more likely to receive special education than females, who more often failed a grade. Academic achievement was not affected in aneuploid children with higher levels of intelligence. Overall, these results suggest milder impairment than previously reported, particularly among trisomy X females.