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Biomedical subjects

C Johnson

Publications and source records attributed to C Johnson.

At least 19 recordsLinked to original sources
PubMed2006

Structural characterization of Salmonella typhimurium YeaZ, an M22 O-sialoglycoprotein endopeptidase homolog.

The Salmonella typhimurium "yeaZ" gene (StyeaZ) encodes an essential protein of unknown function (StYeaZ), which has previously been annotated as a putative homolog of the Pasteurella haemolytica M22 O-sialoglycoprotein endopeptidase Gcp. YeaZ has also recently been reported as the first example of an RPF from a gram-negative bacterial species. To further characterize the properties of StYeaZ and the widely occurring MK-M22 family, we describe the purification, biochemical analysis, crystallization, and structure determination of StYeaZ. The crystal structure of StYeaZ reveals a classic two-lobed actin-like fold with structural features consistent with nucleotide binding. However, microcalorimetry experiments indicated that StYeaZ neither binds polyphosphates nor a wide range of nucleotides. Additionally, biochemical assays show that YeaZ is not an active O-sialoglycoprotein endopeptidase, consistent with the lack of the critical zinc binding motif. We present a detailed comparison of YeaZ with available structural homologs, the first reported structural analysis of an MK-M22 family member. The analysis indicates that StYeaZ has an unusual orientation of the A and B lobes which may require substantial relative movement or interaction with a partner protein in order to bind ligands. Comparison of the fold of YeaZ with that of a known RPF domain from a gram-positive species shows significant structural differences and therefore potentially distinctive RPF mechanisms for these two bacterial classes.

Amino Acid Sequence↗
PubMed2006

The DNA sequence and biological annotation of human chromosome 1.

The reference sequence for each human chromosome provides the framework for understanding genome function, variation and evolution. Here we report the finished sequence and biological annotation of human chromosome 1. Chromosome 1 is gene-dense, with 3,141 genes and 991 pseudogenes, and many coding sequences overlap. Rearrangements and mutations of chromosome 1 are prevalent in cancer and many other diseases. Patterns of sequence variation reveal signals of recent selection in specific genes that may contribute to human fitness, and also in regions where no function is evident. Fine-scale recombination occurs in hotspots of varying intensity along the sequence, and is enriched near genes. These and other studies of human biology and disease encoded within chromosome 1 are made possible with the highly accurate annotated sequence, as part of the completed set of chromosome sequences that comprise the reference human genome.

Base Sequence↗
PubMed2006

Challenges associated with the definition and assessment of inappropriate sexual behaviour amongst individuals with an acquired neurological impairment.

The subject of Inappropriate Sexual Behaviour (ISB) amongst clients with neurological impairment, specifically Acquired Brain Injury (ABI) and dementia, has received limited coverage to date within the literature. This paper discusses some of the problems encountered in the definition and quantification of ISB, in particular the absence of standardized measurement tools to record ISB within an inpatient setting. Whilst ISB is reported to be less prevalent than other behavioural sequelae of brain injury or dementia, it is suggested that its impact on patients and carers can be significant. Ill-defined terminology and the absence of relevant assessment tools add to the specific challenges of understanding and managing ISB within a care or rehabilitation setting. As a result, it is argued that the subjective attitudes of staff and the culture of an institution can dominate the approach taken to dealing with ISB for these client groups.

Aged↗
PubMed2006

Measurement of stain removal in vitro: a comparison of two instrumental methods.

AIM: The aim of this study was to compare an established spectrophotometrical approach for the measurement of stain removal in vitro with a new digital image analysis system. METHOD: Eighteen acrylic blocks were stained by cycling them through human saliva (2 min), chlorhexidine (2 min) and tea (1 h), rinsed with deionized water and left to air dry. The absorbance of each block was then measured at 395 nm using a single-beam spectrophotometer. The lightness (L-value) of the stained blocks (after a baseline correction) was measured using digital image analysis. Image acquisition and L-values were obtained using Adobe Photoshop software. The stain removal ability of two whitening toothpastes and deionized water was tested by immersing each stained block in a test slurry (15 g paste/60 ml deionized water) for 1 min, rinsing and finally left to air dry. This cycle was repeated until the blocks had 5 min exposure to the slurry. Absorbance values from spectrophotometry and L-values by image analysis were obtained after each cycle. RESULTS: Fleiss' coefficient of reliability for intra-operator repeatability of the image analysis system and spectrophotometry was 0.999 for both methods which shows excellent reliability. Pearson's correlation coefficients for the two methods (stain build-up) were 0.976. Test products A, B and C gave correlations of 0.962, 0.998 and 0.817 respectively (stain removal), significant at the 0.01 level. CONCLUSION: The image system is a reliable alternative measurement method validated here against spectrophotometry for stain removal in vitro, and can provide full colour measurement.

Anti-Infective Agents, Local↗
PubMed2006

Item 291--progress in cooperation between GPs and psychiatrists.

With a 12 month prevalence for mental health disorders at just over 17% and data indicating that 75% of those who seek help for a mental health problem do so in the first instance from a general practitioner, there is a strong need for GPs and psychiatrists to work together in providing mental health care for Australians.

Australia↗
PubMed2005

Tissue-specific accumulation of cadmium in subcellular compartments of eastern oysters Crassostrea virginica Gmelin (Bivalvia: Ostreidae).

Cadmium distribution was studied in different subcellular fractions of gill and hepatopancreas tissues of eastern oysters Crassostrea virginica. Oysters were exposed for up to 21 days to low sublethal Cd concentrations (25 microg L(-1)). Gill and hepatopancreas tissues were sampled and divided into organelle fractions and cytosol by differential centrifugation. Organelle content of different fractions was verified by activities of marker enzymes, citrate synthase and acid phosphatase for mitochondria and lysosomes, respectively. In both tissue types, there was a significant accumulation of cadmium in cytosol reaching 230-350 ng mg(-1) protein. Among organelles, mitochondria were the main target for Cd bioaccumulation in gills (250-300 ng mg(-1) protein), whereas in hepatopancreas tissues, the highest cadmium accumulation occurred in lysosomes (90-94 ng mg(-1) protein). Although 75-83% of total cadmium burden was associated with the cytosol reflecting high volume fraction of this compartment, Cd concentrations in organelle fractions reached levels that could cause dysfunction of mitochondria and lysosomes. Organ- and organelle-specific patterns of cadmium bioaccumulation support our previous in vivo studies, which showed adverse effects of cadmium exposures on mitochondrial oxidation in gills and on the lysosomal system of hepatopancreas. This may have important implications for the development of biomarkers of effect for heavy metals and for understanding the mechanisms of toxic effects of metals.

Acid Phosphatase↗
PubMed2005

The relationship between potentially erosive storm energy and daily rainfall quantity in England and Wales.

Erosive storm energy is the primary driver of soil detachment, and hence a major determinant of transfer of sediment and particulate phosphorus (P) to surface waters. Modelling of sediment and P loss at catchment scale, for example for the development of catchment and national mitigation policies, requires a spatially interpolated estimate of variation in erosion risk. To this end we present a method of estimating total rainfall erosivity, as kinetic energy (KE), for any location in England and Wales, from daily rainfall data or monthly climate data. Analysis of detailed, high-resolution records from eleven contrasting sites showed strong predictive correlations between daily rainfall quantity and associated daily total kinetic energy estimated from hourly rainfall intensities. The coefficients showed systematic seasonal variation, with greatest KE per unit of rainfall in late summer and autumn months. In contrast, no systematic spatial variation was found as a function of location or continentality index. The relationships were integrated with probability distributions of rainfall quantity per rain day derived from spatial climate data (monthly rainfall totals and numbers of rain days). The resulting map captures and quantifies the effects of rainfall quantity and intensity patterns on risk of sediment detachment, and as such provides a critical input layer to catchment-scale models of sediment and P transfer.

England↗
PubMed2004

Regulation of 5alpha-reductase isoforms by oxytocin in the rat ventral prostate.

Oxytocin (OT) is present in the male reproductive tract, where it is known to modulate contractility, cell growth, and steroidogenesis. Little is known about how OT regulates these processes. This study describes the localization of OT receptor in the rat ventral prostate and investigates if OT regulates gene expression and/or activity of 5alpha-reductase isoforms I and II. The ventral prostates of adult male Wistar rats were collected following daily sc administration of saline (control), OT, a specific OT antagonist or both OT plus antagonist for 3 d. Expression of the OT receptor was identified in the ventral prostate by RT-PCR and Western blot, and confirmed to be a single active binding site by radioreceptor assay. Immunohistochemistry localized the receptor to the epithelium of prostatic acini and to the stromal tissue. Real-time RT-PCR determined that OT treatment significantly reduced expression of 5alpha-reductase I but significantly increased 5alpha-reductase II expression in the ventral prostate. Activity of both isoforms of 5alpha-reductase was significantly increased by OT, resulting in increased concentration of prostatic dihydrotestosterone. In conclusion, OT is involved in regulating conversion of testosterone to the biologically active dihydrotestosterone in the rat ventral prostate. It does so by differential regulation of 5alpha-reductase isoforms I and II.

Animals↗
PubMed2004

The DNA sequence and comparative analysis of human chromosome 10.

The finished sequence of human chromosome 10 comprises a total of 131,666,441 base pairs. It represents 99.4% of the euchromatic DNA and includes one megabase of heterochromatic sequence within the pericentromeric region of the short and long arm of the chromosome. Sequence annotation revealed 1,357 genes, of which 816 are protein coding, and 430 are pseudogenes. We observed widespread occurrence of overlapping coding genes (either strand) and identified 67 antisense transcripts. Our analysis suggests that both inter- and intrachromosomal segmental duplications have impacted on the gene count on chromosome 10. Multispecies comparative analysis indicated that we can readily annotate the protein-coding genes with current resources. We estimate that over 95% of all coding exons were identified in this study. Assessment of single base changes between the human chromosome 10 and chimpanzee sequence revealed nonsense mutations in only 21 coding genes with respect to the human sequence.

Animals↗
PubMed2004

DNA sequence and analysis of human chromosome 9.

Chromosome 9 is highly structurally polymorphic. It contains the largest autosomal block of heterochromatin, which is heteromorphic in 6-8% of humans, whereas pericentric inversions occur in more than 1% of the population. The finished euchromatic sequence of chromosome 9 comprises 109,044,351 base pairs and represents >99.6% of the region. Analysis of the sequence reveals many intra- and interchromosomal duplications, including segmental duplications adjacent to both the centromere and the large heterochromatic block. We have annotated 1,149 genes, including genes implicated in male-to-female sex reversal, cancer and neurodegenerative disease, and 426 pseudogenes. The chromosome contains the largest interferon gene cluster in the human genome. There is also a region of exceptionally high gene and G + C content including genes paralogous to those in the major histocompatibility complex. We have also detected recently duplicated genes that exhibit different rates of sequence divergence, presumably reflecting natural selection.

Base Composition↗
PubMed2004

The DNA sequence and analysis of human chromosome 13.

Chromosome 13 is the largest acrocentric human chromosome. It carries genes involved in cancer including the breast cancer type 2 (BRCA2) and retinoblastoma (RB1) genes, is frequently rearranged in B-cell chronic lymphocytic leukaemia, and contains the DAOA locus associated with bipolar disorder and schizophrenia. We describe completion and analysis of 95.5 megabases (Mb) of sequence from chromosome 13, which contains 633 genes and 296 pseudogenes. We estimate that more than 95.4% of the protein-coding genes of this chromosome have been identified, on the basis of comparison with other vertebrate genome sequences. Additionally, 105 putative non-coding RNA genes were found. Chromosome 13 has one of the lowest gene densities (6.5 genes per Mb) among human chromosomes, and contains a central region of 38 Mb where the gene density drops to only 3.1 genes per Mb.

Chromosome Mapping↗
PubMed2004

[Buruli disease and plastic surgery].

The Buruli ulcer is a skin infection with Mycobacterium ulcerans which progresses silently. This infection affects mostly women and children who live near stagnant waters. Buruli ulcer is disease that has terrible consequences if not promptly diagnosed and treated. It destroys progressively skin tissues and consequently leaves very important scars. There is no efficient medical treatment. This presentation proposes to take care efficiently of the Buruli ulcer by simple plastic surgery techniques. We relate our experience of a mission in Benin, in the context of the national programme of struggle against the Buruli ulcer.

Adolescent↗
PubMed2004

Interleukin-1beta up-regulates nitrite production: effects on ovarian function.

We have previously reported that Interleukin-1beta (IL-1beta) affects ovarian function in the rat, modulating prostaglandin and progesterone (P) production. As IL-1beta effects were associated to nitric oxide (NO) synthesis, in the present work we have further examined the role of ovarian NOS-system, in IL-1beta antisteroidogenic action. Mid-luteal explants from rats were incubated for 4 h in the presence of IL-1beta (1-35 ng/ml)-alone or in combination with NOS-inhibitors-and then assayed for P and nitrite production. IL-1beta treatment reduced P levels in a dose-dependent manner, returning to basal levels at 35 ng/ml. This reduction in steroid synthesis was paralleled by a dose-dependent increase in nitrite levels, reaching a maximum at 25 ng/ml but without effect at 35 ng/ml. L-Arginine (1 and 2 mM) was able to mimic IL-1beta actions and the NOS blocker L-Nitro-Arginin-Methyl Ester reverted these effects. Moreover, the selective iNOS inhibitor, 1400 W, completely abolished IL-1beta antisteroidogenic effect, therefore confirming the dependence of IL-1beta action upon iNOS activation. Finally, IL-1beta did not affect eNOS expression but up-regulated iNOS mRNA and protein levels. Our results suggest an interaction between IL-1beta and the NOS-system. Thus, we may conclude that in the rat iNOS-derived NO production, induced by IL-1beta, affects ovarian P biosynthesis and hence NO may be a major effector molecule of ovarian IL-1 system.

Animals↗
PubMed2003

The benefits of ribose in cardiovascular disease.

Cardiovascular disease still ranks as the leading cause of death in men and women. Adults have tried to lower their risk of cardiovascular disease by improving their diet, quitting smoking, controlling blood pressure and exercising regularly. Additionally, many adults have turned to nutriceutical or natural products. Myocardial ischemia, produces a depression in myocardial tissue levels of high energy compounds, along with a compromise in myocardial function. Ribose, a naturally occurring sugar, has been extensively investigated, both in animal and clinical studies, as an agent to enhance the recovery of these depressed energy compounds. Results of these studies have been promising in enhancing the recovery of these energy molecules along with an improvement in myocardial function. Therefore, ribose should be considered as a potential agent in the treatment of ischemic cardiovascular disease.

Animals↗
PubMed2003

The effect of cervical rotation on blood flow in the contralateral vertebral artery.

Twenty asymptomatic volunteers (mean age 33 years, range 26 - 54 years) underwent investigation using duplex Doppler ultrasound with real-time imaging and colour flow enhancement. With the subjects seated, peak velocity at C1-2 and volume flow rate at C5-6 were measured in the artery contralateral to the direction of rotation, in the four positions of neutral, 45 degrees and end range rotation, plus a subsequent neutral position. No change in peak velocity at C1-2 between the initial neutral measurement and the measurements at 45 degrees and end range rotation was found (P>0.05). Peak velocity was less in both vertebral arteries on return to the neutral position as compared with end range rotation, however the difference was significant for the left vertebral artery only (P=0.005). This lends support for the rest period, which is taken between cervical movement tests when conducting pre-manipulative testing, to allow for any latent effect on blood flow of the tests themselves. There was no change in volume flow rate between any of the test positions (P=0.349). There was no indication of a cumulative effect of the test procedure (P>0.05).

Adult↗
PubMed2003

Platelet storage solution improves the in vitro function of preserved platelet concentrate.

BACKGROUND AND OBJECTIVES: Stored platelets develop biochemical lesions, manifest as depressed haemostatic function, clot retraction and wound healing. ViaCyte trade mark, a proprietary experimental preservative solution (comprising D-ribose, D-glucose, Hanks solution, Hepes solution, bovine serum albumin, tic anticoagulant peptide and sterile water), was tested in comparison with the presently accepted storage solution, citrate-dextrose-phosphate-plasma (CDP-P), to evaluate its ability to preserve platelet function during storage. MATERIALS AND METHODS: Platelets stored in ViaCyte and platelets suspended in CDP-P were transferred to polypropylene tubes with PL732 covers and analysed for adenine nucleotide levels (ATP molecules), in vitro agonist-mediated P-selectin expression and aggregation. RESULTS: After 5 days of storage at room temperature, 12.2% of platelets stored in ViaCyte exhibited P-selectin expression at rest, and 64.2% exhibited P-selectin expression upon activation with thrombin challenge, an increase of 52%. Platelets stored in CDP-P exhibited 44.4% P-selectin expression at rest, suggesting significant activation during storage, and thrombin stimulation resulted in P-selectin expression of 47.9%, an increase of only 2.5% (P< or =0.002, untreated vs. treated). ViaCyte also maintained ATP levels throughout the storage period, while these levels became depressed in platelets stored in CDP-P (P< or =0.02, untreated vs. treated). Storing platelets in the experimental preservative solution maintained their ability to aggregate, while control platelets lost their ability to aggregate in response to agonist. CONCLUSIONS: ViaCyte appears to protect platelets during storage, reflected by a low level of induced lesions. Platelets stored in ViaCyte maintain energy levels at their resting state, which preserves their ability to aggregate and secrete granule contents, and ensures the availability of additional platelets for activation upon in vitro challenge.

Adenosine Triphosphate↗
PubMed2003

The effect of feeding ractopamine (Paylean) on muscle quality and sensory characteristics in three diverse genetic lines of swine.

The present experiment utilized Berkshire (n = 76), Duroc (n = 81), and high-lean commercial crossbred (n = 75) barrows and gilts with an initial BW of approximately 85.1 kg. Pigs were fed a standard commercial diet (17.6% CP, 1.02% lysine) supplemented with ractopamine hydrochloride at a level of 0 or 10 ppm for 28 d. The experiment was conducted in a randomized complete block design, with animals blocked within genetic line according to litter, gender, and weight, for a total of four blocks per genetic line for each treatment. Pigs were harvested at a commercial abattoir and chilled for 24 h at 1 to 4 degrees C. At 24 h postmortem, wetness and firmness scores and ultimate muscle pH were measured in the center of the longissimus muscle (LM) at the 10th to 11th rib interface. Visual and instrumental color and marbling score were measured at 48 h postmortem on a fresh cut LM surface. Percentage of chemically extracted intramuscular fat (IMF) was measured, and a trained sensory panel evaluated cooked LM chops for juiciness, tenderness, and chewiness. Cooking loss (%) and instrumental measurement of tenderness also were measured on cooked LM chops. Ractopamine treatment increased ADG (P < 0.01) and LM area (P < 0.05), but had no effect (P > 0.05) on LM quality, sensory attributes, or instrumental measures of palatability. Berkshire LM received higher tenderness and juiciness (P < 0.05) scores and had lower cooking losses (P < 0.05) and instrumental tenderness (P < 0.05) than LM from the Duroc and high-lean lines. Loins from barrows were firmer (P < 0.05), had lower drip loss percentages (P < 0.05), and received greater tenderness scores (P < 0.05) than the LM from gilts. Genetic line x treatment and gender x treatment interactions were detected for IMF. The LM of Berkshire pigs fed ractopamine had lower (P < 0.05) IMF than Berkshires fed the control diet, with no interaction in the other lines. Purebred barrows (Berkshire and Duroc) had greater (P < 0.001 and P < 0.05, respectively) IMF than their respective purebred gilts, with no gender difference in IMF in the high-lean line. Results from the present study indicate that feeding ractopamine does not affect most muscle quality and palatability characteristics. However, the genetic line x treatment interaction for loin IMF suggests that feeding ractopamine might reduce IMF within the loin muscle of genetic lines that have a propensity to produce greater levels of IMF.

Adipose Tissue↗