Biomedical subjects

D Peters

Publications and source records attributed to D Peters.

At least 19 recordsLinked to original sources

PubMed2006

Molecular and biological comparison of two Tomato yellow ring virus (TYRV) isolates: challenging the Tospovirus species concept.

Two strains of Tomato yellow ring virus (TYRV, genus Tospovirus), one from tomato (referred to as TYRV-t) and the other from soybean and potato (denoted TYRV-s), collected from different geographical regions in Iran, were compared. Their genomic S RNA segments differed in size by 55 nucleotides. Comparison of the S RNA intergenic regions revealed the absence of a stretch of 115 nucleotides within the S RNA segment of TYRV-s and, conversely, of 56 nts in that of TYRV-t, apparently a stable genetic difference as it was also found in another isolate of TYRV-s collected from potato. Sequence comparison of the N protein ORFs revealed an identity of 92% between the N proteins of both strains, and the observed strong cross-reaction of TYRV-s in DAS-ELISA with a polyclonal antiserum directed against the TYRV-t N protein confirmed this high identity. Host range analysis revealed several differences, e.g. TYRV-s, but not TYRV-t, being able to systemically infect Nicotiana species, and TYRV-s being localised in tomato. The observed molecular and biological differences of both viruses call into question the currently used criteria for Tospovirus species demarcation.

Base Sequence↗

PubMed2006

A 13-week dietary toxicity and toxicokinetic study with l-theanine in rats.

This study was conducted to evaluate the safety of l-theanine (Suntheanine) when administered as a dietary admixture to male and female Crl:CD (SD)GS BR rats at concentrations providing doses of 0, 1500, 3000 or 4000 mg/kg bw/day for 13 weeks. The study design was consistent with OECD Guideline 408 and USFDA Redbook II (1993) and GLP. There were no consistent, statistically significant treatment-related adverse effects on behavior, morbidity, mortality, body weight, food consumption and efficiency, clinical chemistry, hematology, or urinalysis. There were no consistent treatment-related adverse effects in gross pathology, organ weights or ratios or histopathology. The increased incidence of renal tubular cell adenomas in high-dose females only were not consistent with the characteristics of a renal carcinogen (due to early onset and low number of animals affected) but were more consistent with a genetic predisposition than with direct organ toxicity. The no-observed-adverse-effect-level (NOAEL) was 4000 mg/kg bw/day, the highest dose tested.

Animals↗

PubMed2005

Variation in practice of ileal intubation among diverse endoscopy settings: results from a national endoscopic database.

BACKGROUND: Terminal ileum intubation rates at colonoscopy are variable. One of the major indications for terminal ileum intubation is to identify Crohn's disease. Signs and symptoms which raise a suspicion of Crohn's include abdominal pain/bloating, anaemia and diarrhoea. AIM: To determine the proportion of terminal ileal intubation in patients undergoing evaluation of abdominal pain/bloating, anaemia or diarrhoea with normal endoscopic findings at colonoscopy. METHODS: The Clinical Outcomes Research Initiative national endoscopic database was analysed to determine the proportion of terminal ileum intubation in patients undergoing evaluation of either abdominal pain/bloating, anaemia or diarrhoea with normal endoscopic findings at colonoscopy and to characterize this population of patients. Patients with known or suspected inflammatory bowel disease were excluded from the analysis. RESULTS: Between January 2000 and December 2003, 21 638 patients underwent complete colonoscopy for evaluation of either abdominal pain/bloating, anaemia or diarrhoea with normal colon findings. Overall, 3858 patients (18%) underwent terminal ileum evaluation. Intubation rates differed according to procedure indication: abdominal pain (13%), anaemia (13%), diarrhoea (28%). Terminal ileum assessment declined with advancing patient age and was least frequent in Black patients (12% vs. 18% in non-Blacks, P < 0.0001). Ileal intubation rates also varied among endoscopy site types: community (17%), academic (21%), Veterans Affairs Medical Centres (17%), P < 0.0001. Multiple logistic regression identified patients with the indication of diarrhoea (OR: 2.58) as more likely to undergo terminal ileum intubation when compared with those with abdominal pain/bloating. Patients in Veterans Affairs (OR: 1.26) and academic (OR: 1.29) sites were more likely to undergo terminal ileum intubation compared with community sites. CONCLUSION: Less than one-fifth of patients with either abdominal pain/bloating, anaemia or diarrhoea underwent ileal intubation in the setting of a normal colonoscopy. Significant practice variation was observed in rates of terminal ileum evaluation. Further study is required to determine whether terminal ileum examination impacts patient management or outcome.

Adult↗

PubMed2004

Mouse antibody production test: can we do without it?

Introduction of microbiologically contaminated materials into mice can cause infections of the recipients and jeopardize experimental protocols. As such, the methods used to screen biological materials should be sensitive, reliable and suitable for routine diagnostic work. In this report, the sensitivity of the viral plaque assay, mouse antibody production test and polymerase chain reaction (PCR) for detection of MHV-A59 and MMVp, two of the most prevalent pathogenic viruses in experimental mouse facilities, was compared. Analysis of serial tenfold dilutions of virus stocks revealed that the sensitivity of the mouse antibody production test on day 28 (10(-10) dilution) was at least 10 times higher than that of the viral plaque assay (10(-9) dilution) and 10(4) times more than that of the RT-PCR (10(-6) dilution) for detection of MHV-A59. For detection of MMVp, the PCR (10(-10) dilution) proved to be 10(6) times more sensitive than the viral plaque assay (10(-4) dilution) and the mouse antibody production test on day 28 (10(-4) dilution) which were equally sensitive. Based on the present study, it was shown that the method for diagnosis of viruses in biological materials should be employed only after the sensitivity has been determined for the viruses of interest implying that the most sensitive method needs to be determined independently for each virus.

Animals↗

PubMed2003

Characterisation of the feeding behaviour of western flower thrips in terms of electrical penetration graph (EPG) waveforms.

Western flower thrips, Frankliniella occidentalis (Pergande) causes damage to plants when they are feeding. Also, this thrips species transmits Tomato spotted wilt virus (TSWV) during stylet penetration. We investigated the penetration behaviour (probing) of thrips on pepper leaves and on liquid diet by electrical penetration graph (EPG, DC-system) recording. In addition, we used high-magnification video observations to correlate EPG waveforms with the insect's posture, head movements, and muscle contractions. Also, EPGs were correlated with probing on liquid diets containing radio-active tracers to distinguish and quantify ingestion waveforms. The previously described waveforms P, Q, and R were distinguished and additionally, a new waveform 'S' was distinguished. Waveform P could be linked with mandibular leaf penetration, waveform Q presumably with insertion of the maxillary stylets, and waveform R with ingestion of cell contents, whereas waveform S could not be correlated with any behavioural activity. Histology of the feeding damage in pepper leaves shows that thrips ingests the contents of multiple cells per probe.

Animals↗

PubMed2003

Prenatal nicotine exposure and behavior.

Prenatal exposure to nicotine has been associated with changes in behavioral indices in offspring. Flank marking, a scent-marking behavior in golden hamsters, appears to be controlled by arginine vasopressin (AVP) neurons in the hypothalamus. The present study examines the effects of prenatal exposure to nicotine on the vasopressinergic system associated with flank marking behavior.

Animals↗

PubMed2002

The route of tomato spotted wilt virus inside the thrips body in relation to transmission efficiency.

The route of tomato spotted wilt virus (TSWV) in the body of its vectors, Frankliniella occidentalis and Thrips tabaci (Thysanoptera: Thripidae) was studied during their development. First instar larvae were allowed, immediately upon hatching, to acquire virus from mechanically infected Datura stramonium plants for 24 h. The rate of transmission by adults was determined in inoculation access feeding test on Emilia sonchifolia leaf disks. Thrips tissues were analysed for infection at 24 h intervals after the acquisition-access feeding period, and assayed by the whole-mount immuno-fluorescent staining technique. The virus was initially detected in the proximal midgut region in larvae of both species, and then in the second and third midgut regions, foregut, and salivary glands. Occasionally the first infections of the salivary glands were already detected in one-day-old second stage larvae. The intensity of the infection in the various organs of the thrips of each species was positively related to the transmission efficiency. In both thrips populations good agreement was found between the percentage of second instar larvae and adults with at least one infected salivary gland lobe and the percentage of transmitting adults. These results support the contention that the virus must reach the salivary glands before thrips pupation in order to be transmitted by old second instar larvae and adults.

Animals↗

PubMed2002

Genetic organisation of Iris yellow spot virus M RNA: indications for functional homology between the G(C) glycoproteins of tospoviruses and animal-infecting bunyaviruses.

The complete nucleotide sequence (4838 nucleotides) of Iris yellow spot virus (IYSV) M RNA indicates, typical for tospoviruses, the presence of two genes in ambisense arrangement. The vRNA ORF codes for the potential cell-to-cell movement (NSm) protein (34.8 kDa) and the vcRNA ORF for the viral glycoprotein (G1/G2) precursor (128.6 kDa). Multiple sequence alignment of the NSm and G1/G2 precursor proteins of IYSV with those of other tospoviruses, showed highest homologies to Peanut bud necrosis virus (PBNV) and Watermelon silver mottle virus (WSMV). The potential cell-to-cell movement protein of tospoviruses is highly conserved (40-70% identity), with the exception of the first 60 N terminal amino acids, a domain that clearly diverged. For the G1 and G2 viral glycoproteins, blast searches revealed a significant homology between the C-terminally located tospoviral G1 (G(C)) protein with the counterpart of the animal-infecting bunyaviruses, suggesting a functional homology for these proteins.

Amino Acid Sequence↗

PubMed2002

Sahaja yoga in the management of moderate to severe asthma: a randomised controlled trial.

BACKGROUND: Sahaja Yoga is a traditional system of meditation based on yogic principles which may be used for therapeutic purposes. A study was undertaken to assess the effectiveness of this therapy as an adjunctive tool in the management of asthma in adult patients who remained symptomatic on moderate to high doses of inhaled steroids. METHODS: A parallel group, double blind, randomised controlled trial was conducted. Subjects were randomly allocated to Sahaja yoga and control intervention groups. Both the yoga and the control interventions required the subjects to attend a 2 hour session once a week for 4 months. Asthma related quality of life (AQLQ, range 0-4), Profile of Mood States (POMS), level of airway hyperresponsiveness to methacholine (AHR), and a diary card based combined asthma score (CAS, range 0-12) reflecting symptoms, bronchodilator usage, and peak expiratory flow rates were measured at the end of the treatment period and again 2 months later. RESULTS: Twenty one of 30 subjects randomised to the yoga intervention and 26 of 29 subjects randomised to the control group were available for assessment at the end of treatment. The improvement in AHR at the end of treatment was 1.5 doubling doses (95% confidence interval (CI) 0.0 to 2.9, p=0.047) greater in the yoga intervention group than in the control group. Differences in AQLQ score (0.41, 95% CI -0.04 to 0.86) and CAS (0.9, 95% CI -0.9 to 2.7) were not significant (p>0.05). The AQLQ mood subscale did improve more in the yoga group than in the control group (difference 0.63, 95% CI 0.06 to 1.20), as did the summary POMS score (difference 18.4, 95% CI 0.2 to 36.5, p=0.05). There were no significant differences between the two groups at the 2 month follow up assessment. CONCLUSIONS: This randomised controlled trial has shown that the practice of Sahaja yoga does have limited beneficial effects on some objective and subjective measures of the impact of asthma. Further work is required to understand the mechanism underlying the observed effects and to establish whether elements of this intervention may be clinically valuable in patients with severe asthma.

Adolescent↗

PubMed2001

Graft survival in a rhesus renal transplant model after immunotoxin-mediated T-cell depletion is enhanced by mycophenolate and steroids.

BACKGROUND: Anti-CD3 immunotoxin (IT), a T-cell-depleting agent, prolongs survival of renal allografts in a rhesus monkey model without the need for long-term immunosuppression. In this study we sought to further prolong allograft survival by giving short-term conventional immunosuppression simultaneous with IT administration. METHODS: MHC class II mismatched, juvenile rhesus monkeys were paired as donor and recipient for renal transplantation. Recipients received two to three daily doses of IT starting on the day of transplantation. Additional immunosuppression was given for no more than 60 days. Graft function was monitored by serum creatinine and renal biopsies. Flow cytometry was used to monitor T-cell recovery. RESULTS: Graft survival time (GST) in animals receiving IT was prolonged compared with controls with 50% of IT-treated monkeys surviving >100 days. Animals treated with IT plus mycophenolate mofetil (MMF) and steroids had significantly enhanced GST (mean GST, 305 days) compared with those treated with IT alone (mean GST, 94 days). In contrast, addition of cyclosporine or 40-O-[2-Hydroxyethyl]rapamycin did not significantly increase graft survival time. A comparison among animals from all treatment groups with short (<100 days) and long (>100 days) GST demonstrated that those with the shorter GST had a higher blood T-cell count 2 weeks after transplantation. Full recovery of CD4+ T cells required longer than 6 months. CONCLUSIONS: A combination with MMF and steroids given for 4 days after renal allograft transplantation significantly increases GST in IT-treated monkeys. We hypothesize that MMF and steroids suppress the initial T-cell activation mediated by IT.

Animals↗

PubMed2001

Successful conversion from conventional immunosuppression to anti-CD154 monoclonal antibody costimulatory molecule blockade in rhesus renal allograft recipients.

BACKGROUND: Several conventional forms of immunosuppression have been shown to antagonize the efficacy of anti-CD154 monoclonal antibody- (mAb) based costimulatory molecule blockade immunotherapy. Our objective was to determine if allograft recipients treated with a conventional immunosuppressive regimen could be sequentially converted to anti-CD154 mAb monotherapy without compromising graft survival. METHODS: Outbred juvenile rhesus monkeys underwent renal allotransplantation from MHC-disparate donors. After a 60-day course of triple therapy immunosuppression with steroids, cyclosporine, and mycophenolate mofetil, monkeys were treated with: (1) cessation of all immunosuppression (control); (2) seven monthly doses of 20 mg/kg hu5C8 (maintenance), or; (3) 20 mg/kg hu5C8 on posttransplant days 60, 61, 64, 71, 79, and 88 followed by five monthly doses (induction+maintenance). Graft rejection was defined by elevation in serum creatinine>1.5 mg/dl combined with histologic evidence of rejection. RESULTS: Graft survival for the three groups were as follows: group 1 (control): 70, 75, >279 days; group 2 (maintenance): 83, 349, >293 days, and; group 3 (induction+maintenance): 355, >377, >314 days. Acute rejection developing in two of four monkeys after treatment with conventional immunosuppression was successfully reversed with intensive hu5C8 monotherapy. CONCLUSIONS: Renal allograft recipients can be successfully converted to CD154 blockade monotherapy after 60 days of conventional immunosuppression. An induction phase of anti-CD154 mAb appears to be necessary for optimal conversion. Therefore, although concurrent administration of conventional immunosuppressive agents including steroids and calcineurin inhibitors has been shown to inhibit the efficacy of CD154 blockade, sequential conversion from these agents to CD154 blockade appears to be effective.

Animals↗

PubMed2001

The pseudomolecule method and the structure of globular proteins. II. The example of ribonuclease F1 and T1.

The pseudomolecule approach to the structure of globular proteins in which a small number of water molecules are incorporated into the "molecule" is tested again by comparing the ribbon of hydrogen bonds in two proteins, ribonuclease F1 and T1. These two molecules are 59% homologous and have the same backbone conformation both globally and locally. The two ribbons of hydrogen bonds that cover the whole of the backbone are conserved with an accuracy of some 95% providing that allowance is made for the intrusion into one of the pair of such extra factors as the presence of adducts or metal ions, the insertions and the absence of a few water molecules from one of the x-ray data sets. Without these corrections, the conservation of the ribbon is some 85%. There are 35 conserved hydrogen-bonding residues, nearly all of which show many unions to the backbone or interactions with the active site. There are 36 point mutations that involve one or two hydrogen-bonding side chains and nearly all of these have either none or one hydrogen bond to the backbone. These are minor contributors to the ribbon of hydrogen bonds. Of the 71 residues involved in these two categories, all but six fit into the pseudomolecular picture of the structure of globular proteins. The remaining 30 residues almost all contain conserved hydrocarbon side chains that may have a second order effect on the structure through their space filling effects.

Amino Acid Sequence↗

PubMed2001

Identification and characterization of a novel tospovirus species using a new RT-PCR approach.

A novel tospovirus serologically distinct from all established tospovirus species was found in Thailand in Physalis minima L. The S RNA of this virus was cloned by a new RT-PCR approach revealing a nucleotide sequence of 3257 nucleotides. The ambisense RNA segment encoded a nonstructural protein (NSs) of 469 amino acids, with a predicted Mr of 53.2 kDa, and a nucleoprotein (N) of 279 amino acids and a Mr of 31.0 kDa, so far the largest N protein known for any tospovirus species. N protein sequence comparisons revealed closet relationship to the species Watermelon bud necrosis virus (58% identity), Watermelon silver mottle virus and Peanut bud necrosis virus (57%) and a distant relationship to Peanut yellow spot virus (23%) and Peanut chlorotic fanspot virus (22%).

Amino Acid Sequence↗

PubMed2001

Novel AMPA receptor potentiators LY392098 and LY404187: effects on recombinant human AMPA receptors in vitro.

The present study describes the activity of two novel potent and selective AMPA receptor potentiator molecules LY392098 and LY404187. LY392098 and LY404187 enhance glutamate (100 microM) stimulated ion influx through recombinant homomeric human AMPA receptor ion channels, GluR1-4, with estimated EC(50) values of 1.77 microM (GluR1(i)), 0.22 microM (GluR2(i)), 0.56 microM (GluR2(o)), 1.89 microM (GluR3(i)) and 0.20 microM (GluR4(i)) for LY392098 and EC(50) values of 5.65 microM (GluR1(i)), 0.15 microM (GluR2(i)), 1.44 microM (GluR2(o)), 1.66 microM (GluR3(i)) and 0.21 microM (GluR4(i)) for LY404187. Neither compound affected ion influx in untransfected HEK293 cells or GluR transfected cells in the absence of glutamate. Both compounds were selective for activity at AMPA receptors, with no activity at human recombinant kainate receptors. Electrophysiological recordings demonstrated that glutamate (1 mM)-evoked inward currents in human GluR4 transfected HEK293 cells were potentiated by LY392098 and LY404187 at low concentrations (3-10 nM). In addition, both compounds removed glutamate-dependent desensitization of recombinant GluR4 AMPA receptors. These studies demonstrate that LY392098 and LY404187 allosterically potentiate responses mediated by human AMPA receptor ion channels expressed in HEK 293 cells in vitro.

Allosteric Regulation↗

PubMed2001

Synthesis and evaluation of racemic [(11)C]NS2456 and enantiomers as selective serotonin reuptake radiotracers for PET.

Positron emission tomography (PET) radiotracers are needed for quantifying serotonin uptake sites in the living brain. Therefore, we evaluated a new selective serotonin reuptake inhibitor, NS2456, to determine whether it is suited for use in PET. Racemic NS2456 [(1RS,5SR)-8-methyl-3-[4-trifluoromethoxyphenyl]-8-azabicyclo [3.2.1]oct-2-ene] and its N-demethylated analog, racemic NS2463, selectively inhibited serotonin uptake in rat brain synaptosomes; their IC(50) values were 3000-fold lower for [(3)H]serotonin than for either [(3)H]dopamine or [(3)H]noradrenaline. The enantiomers of NS2463 were also potent inhibitors of serotonin uptake in vitro, but they failed to show stereoselectivity. Racemic NS2463 as well as its enantiomers were radiolabelled by N-methylation with C-11, yielding [(11)C]NS2456 for use in PET of the living porcine brain. The compounds crossed the blood-brain barrier rapidly and accumulated preferentially in regions rich in serotonin uptake sites (e.g., brainstem, subthalamus and thalamus). However, their binding potentials were relatively low and no stereoselectivity was found. Thus, neither racemic [(11)C]NS2456 nor its [(11)C]-labelled enantiomers are ideal for PET neuroimaging of neuronal serotonin uptake sites.

Animals↗

PubMed2001

Sonolytic degradation of volatile pollutants in natural ground water: conclusions from a model study.

In order to evaluate the possibilities of an ultrasound-based cleaning technology, the effects of sonication on pollutants in a contaminated natural ground water were investigated. After the discussion of the results from this model study on the sonolytic degradation of volatile organic compounds, some consequences are reported and the important role of water components is described. Furthermore, the use of sonication as a cleaning technology for polluted water is discussed based on the conclusions from this study.

Hydrocarbons, Chlorinated↗

PubMed2001

Sarcomere number regulation maintained after immobilization in desmin-null mouse skeletal muscle.

The serial sarcomere number of skeletal muscle changes in response to chronic length perturbation. The role of the intermediate filament desmin in regulating these changes was investigated by comparing the architectural adaptations of the tibialis anterior, extensor digitorum longus (EDL) and soleus from wild-type mice with those of homozygous desmin knockout mice after hindlimb immobilization. After 28 days, serial sarcomere number increased significantly in the lengthened wild-type tibialis anterior (by approximately 9%) and EDL (by approximately 17%). Surprisingly, muscles from desmin knockout mice also experienced significant serial remodeling, with the serial sarcomere number of the tibialis anterior increasing by approximately 10% and that of the EDL by approximately 27%. A consistent result was observed in the shortened soleus: a significant decrease in sarcomere number was observed in the muscles from both wild-type (approximately 26%) and knockout (approximately 12%) mice. Thus, although desmin is not essential for sarcomerogenesis or sarcomere subtraction in mouse hindlimb muscles, the results do suggest subtle differences in the nature of sarcomere number adaptation. We speculate that desmin may play a role in regulating the optimal arrangement of sarcomeres within the muscle or in sensing the magnitude of the immobilization effect itself.

Animals↗

PubMed2001

Value of CD23 determination by flow cytometry in differentiating mantle cell lymphoma from chronic lymphocytic leukemia/small lymphocytic lymphoma.

Mantle cell lymphoma (MCL) and chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL) share many morphologic and immunophenotypic features. In addition to histomorphologic examination, it is customary to use the absence of CD23 to differentiate MCL from CLL/SLL, based primarily on reported comparisons of immunohistochemical staining of tissue sections. These findings are widely extrapolated to flow cytometric analysis, although available data are contradictory and not sufficiently detailed. We compared expression of CD23 by flow cytometry in 22 cases of MCL and 25 cases of CLL/SLL. Lymphoma cells in 12 of 22 MCLs were negative for CD23, and 10 showed dim expression. In contrast, none of 25 CLL/SLLs were negative for CD23, 4 were dimly positive, and 21 were moderately or brightly positive. Thus, a significant proportion of MCL exhibited overlap of CD23 expression in the low-intensity range with CLL/SLL. Clinically, there was no correlation between the intensity of CD23 expression and clinical stage at diagnosis or survival. These findings emphasize that by flow cytometry, MCL can be differentiated reliably from CLL/SLL using CD23 if negative expression is observed. However, with dimly positive expression, interpretation should be cautious.

Adult↗