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Biomedical subjects

D Peters

Publications and source records attributed to D Peters.

At least 37 records · Page 2Linked to original sources
PubMed1995

Occurrence and role of an early antigen and evidence for transforming ability of porcine circovirus.

By means of indirect immunofluorescence assay (IFA) using natural swine immune serum and hyperimmune serum from rabbits infected with porcine circovirus (PCV), a PCV antigen was detected present prior to the onset of viral and cellular DNA synthesis in nucleoli of cells of synchronized and growth stimulated infected PS cell cultures grown for more than 12 h in the presence of hydroxyurea. The number of cells containing specifically fluorescing nucleoli increased with increasing time of growth in the presence of hydroxyurea. The concomitant increase in the number of cells containing virus structural (VS) antigen in the nuclei and the increase in the amount of replicative (RF) DNA and accompanying 5 S DNA after release from the hydroxyurea block suggest that EA is involved in induction of PCV DNA replication. Primary pig kidney cell cultures persistently infected with PCV survived mock-infected control cultures for 16 passages. They had lost contact inhibition and formed cell colonies in soft agar at a ratio of 0.1 to 0.4%. Cell lines derived from agar colonies showed properties of transformed cells e.g. low requirement for serum growth factors, ability to overgrow a continuous cell layer, anchorage independence of growth. In transformed cells stimulated to growth and grown in the presence of hydroxyurea, non-structural viral antigen visible by IFA in nucleoli and VS antigen located in the cytoplasm were expressed. Contrary to virus bound nuclear VS antigen in productive infection, accumulation of cytoplasmatic VS antigen was independent of DNA synthesis and caused cell destruction, thus limiting growth of cell layers and colonies in soft agar.

Animals↗
PubMed1995

Pharmacological profile and anti-ischemic properties of the Ca(2+)-channel blocker NS-638.

Included in the sequence of events leading to neuronal death in ischemic tissue following stroke is an excessive and toxic rise in the intracellular Ca(2+)-concentration, predominantly due to an influx of Ca2+ through nonselective cation-channels as well as Ca(2+)-channels. In the present study we have characterized the pharmacological profile and anti-ischemic effects of 2-amino-1-(4-chlorobenzyl)-5-trifluoromethylbenzimidazole (NS-638), a small nonpeptide molecule with Ca(2+)-channel blocking properties. NS-638 dose dependently inhibited K(+)-stimulated [45Ca2+]-uptake in chick cortical synaptosomes and 2-amino-3-(3-hydroxy-5-methylisoxazol-4-yl)propionic acid (AMPA)-stimulated [3H]GABA-release from cultured cortical neurons with IC50 values of 2.3 and 4.3 microM, respectively. K(+)-stimulated intracellular Ca(2+)-elevation in cultured cerebellar granule cells was equipotently blocked with an IC50 value of 3.4 microM. At this concentration no effect on Ca(2+)-induced contractions in K(+)-depolarized guinea pig taenia coli was observed. The effect of NS-638 on neuronal Ca(2+)-channels was evaluated using whole cell patch clamp techniques. The compound reversibly blocked N- and L-type Ca(2+)-channels in cultured chick dorsal root ganglion cells in the concentration range of 1-30 microM. In the mouse middle cerebral artery occlusion (MCAO) model, NS-638 administered i.p. (50 mg kg-1) at 1 h and 6 h post-ischemia, and once a day for the next two days, resulted in a 48% reduction in total infarct volume. The compound did not show protection against ischemic neuronal damage in the gerbil model of bilateral carotid artery occlusion (BCAO). This data suggests, that neuronal Ca(2+)-channel blockers may have potential in ameliorating the pathological damage after focal ischemia.

Animals↗
PubMed1994

Expression and subcellular location of the NSM protein of tomato spotted wilt virus (TSWV), a putative viral movement protein.

The 33.6-kDa nonstructural (NSM) protein gene, located on the ambisense M RNA segment of tomato spotted wilt virus (TSWV), was cloned and expressed using the Escherichia coli pET-11t expression system. The protein thus produced was purified and used for the production of a polyclonal antiserum. Western immunoblot analyses of TSWV-infected Nicotiana rustica plants showed NSM synthesis only during a short period early in systemic infection. Although NSM was found associated with cytoplasmic nucleocapsid preparations, it was absent from purified virus particles. Analyses of subcellular fractions from young, systemically infected leaves showed the presence of NSM in fractions enriched for cell walls and cytoplasmic membranes, respectively. Furthermore, immunogold labeling of tissue sections of TSWV-infected N. rustica plants showed that this protein was found associated with nucleocapsid aggregates in the cytoplasm and in close association with plasmodesmata. The data obtained provide evidence that NSM represents the viral movement protein of TSWV, involved in cell-to-cell movement of nonenveloped ribonucleocapsid structures.

Animals↗
PubMed1994

Nitrogen regulation in fungi.

Nitrogen regulation has been extensively studied in fungi revealing a complex array of interacting regulatory genes. The general characterisation of the systems in Aspergillus nidulans and Neurospora crassa shall be briefly described, but much of this paper will concentrate specifically on the recent molecular characterisation of areA, the principle regulatory gene from A. nidulans which mediates nitrogen metabolite repression. Three areas shall be explored in detail, firstly the DNA binding domain, which has been characterised extensively by both molecular and genetic analysis. Secondly we shall report recent analysis which has revealed the presence of related DNA binding activities in A. nidulans. Finally we shall discuss the mechanism by which the nitrogen state of the cell is monitored by the areA product, in particular localisation of the domain within the areA product which mediates the regulatory response within the protein.

Amino Acid Sequence↗
PubMed1994

In situ localisation of beet necrotic yellow vein virus (BNYVV) in rootlets of susceptible and resistant beet plants.

Mechanisms of resistance to beet necrotic yellow vein virus (BNYVV) were studied by comparing the multiplication and distribution of BNYVV in root tissue of some beet accessions. Seedlings were infected either by soil containing resting spores of Polymyxa betae with BNYVV, or by a viruliferous zoospore suspension. With both inoculation methods high virus concentrations were obtained in rootlets of the susceptible cultivar 'Regina'. Using infested soil, low virus concentrations were found in the partially resistant cultivar 'Rima' and in the resistant accessions Holly and WB42. When a zoospore suspension was used, similar virus concentrations occurred in 'Rima' and Holly as in 'Regina', while a low virus concentration was found in WB42. By in situ localisation studies, using immunogold-silver labelling, virus was detected in 'Regina' after infection by soil or a zoospore suspension, but it could only be detected in the resistant accessions after infection by a zoospore suspension. In rootlets of 'Regina', 'Rima' and Holly, virus was found in the epidermis, cortex parenchyma, endodermis, and interstitial parenchyma, but in general not inside the vascular tissue. In WB42 the virus, occurring in small aggregates, seemed to be restricted to the epidermis and some cortex parenchyma cells. Comparing both the multiplication and distribution of BNYVV in rootlets of the accessions studied, it is concluded that the virus resistance mechanism in 'Rima' and Holly is different from that in WB42.

Immunohistochemistry↗
PubMed1994

Sarcoplasmic reticulum Ca2+ pump expression in denervated skeletal muscle.

This study was undertaken as one approach to better understand how contractile activity regulates excitation-contraction coupling phenotype in skeletal muscle. The effects of denervation on the expression of the sarcoplasmic reticulum (SR) Ca(2+)-adenosinetriphosphatase (ATPase), a key protein of the contraction-relaxation cycle, was analyzed in fast-twitch (FT) and slow-twitch (ST) skeletal muscle. Muscle mass, mRNA, and protein expression of specific isoforms of the sarco(endo)plasmic reticulum Ca(2+)-ATPase (SERCA) and contractile parameters related to muscle relaxation were measured in rat soleus and extensor digitorum longus (EDL) muscles at 1, 4, 7, 14, and 28 days after sciatic nerve transection. Wet muscle mass decreased to 35% of control by 28 days of denervation in both soleus and EDL muscles (P < 0.05). Northern and Western analyses showed decreases in mRNA and protein expression of the slow Ca2+ pump isoform (SERCA2a) in the denervated soleus muscle and in the fast Ca2+ pump isoform (SERCA1) in the denervated EDL muscle, particularly at later time points. There was no change in the expression of the alternate isoform in either muscle type. Prolongation of twitch contraction times, slowed rates of tension development, and leftward shifts in frequency-tension curves were consistent with the reduced Ca2+ pump density and suggested slowed Ca2+ handling in SR or denervated ST and FT muscles. The results are in marked contrast with those previously reported in non-weight-bearing muscle induced by biomechanical unloading.

Animals↗
PubMed1994

Musculoskeletal clinic in general practice: study of one year's referrals.

BACKGROUND: A musculoskeletal clinic, staffed by a general practitioner trained in osteopathy, medical acupuncture and intralesional injections, was set up in an inner London general practice in 1987. AIM: A retrospective study was undertaken of one year's referrals to the clinic in 1989-90 to determine how general practitioners were using the clinic in terms of problems referred; consultation patterns of patients attending the clinic and 12 months after initially being seen; and how access to the clinic influenced referrals to relevant hospital departments. METHOD: Day sheets were studied which recorded information on demographic characteristics of patients referred to the clinic and their problems, diagnoses made, duration of symptoms, number and range of treatments given, and recurrence of problems. Use of secondary referral sources was also examined. RESULTS: During the study year 154 of 3264 practice patients were referred to the musculoskeletal clinic, and attended a mean of 3.5 times each. Of all the attenders 64% were women and 52% were 30-54 years old. Eighty one patients (53%) presented with neck, back or sciatic pain. A specific traumatic, inflammatory or other pathological process could be ascribed to only 19% of patients. Regarding treatment, 88% of patients received osteopathic manual treatment or acupuncture, or a combination of these treatments and 4% received intralesional injections. Nine patients from the clinic (6%) were referred to an orthopaedic specialist during the year, two with acute back pain. Referrals to orthopaedic specialists by the practice as a whole were not significantly lower than the national average, although the practice made fewer referrals to physiotherapy and rheumatology departments than national figures would have predicted. Seventeen patients (11%) returned to the clinic with a recurrence of their main complaint within a year of their initial appointment; second courses of treatment were usually brief. CONCLUSION: The clinic encouraged a relatively low referral rate to musculoskeletal specialists outside the practice. However, a need was identified for better communication about the potential of the approaches used in order that referrals to secondary specialists, particularly orthopaedic specialists, could be further reduced.

Acupuncture Therapy↗
PubMed1993

Detection of the L protein of tomato spotted wilt virus.

The 5'-terminal and 3'-terminal parts of the single open reading frame (ORF) in the L RNA of tomato spotted wilt virus (TSWV) were expressed using a prokaryotic expression system. Using antibodies raised against the translational products obtained a 330-kDa protein could be specifically detected in preparations of purified virions and in nucleocapsid preparations from TSWV-infected leaf tissue. The results obtained indicate that the L protein of TSWV, though much larger than that of the animal-infecting bunyaviruses, is present in virus particles in an unprocessed, intact form.

Base Sequence↗
PubMed1993

Icelandic families with autosomal dominant polycystic kidney disease: families unlinked to chromosome 16p13.3 revealed by linkage analysis.

We have mainly used 3 highly polymorphic DNA markers, 3'HVR (D16S85), 16AC2.5 (D16S291) and SM7 (D16S283), flanking the PKD1 region on chromosome 16p13.3 to establish linkage status in seven Icelandic families with autosomal dominant polycystic kidney disease (ADPKD). In four families, the disease locus is in the PKD1 region, and three families are "unlinked" to chromosome 16p13.3. In one of the "unlinked" families, the disease locus is excluded from a part of the long arm of chromosome 2, and we support a theory of more than 2 loci being responsible for ADPKD. Our data confirm the location of the locus YNH24 (D2S44) to chromosome 2q13-q24.

Adult↗
PubMed1993

Distinct levels of relationships between tospovirus isolates.

The taxonomic relations of a number of tospovirus isolates, collected in different geographical areas and from different host plants, were studied. To delineate these isolates, properties such as susceptibility of a limited range of host plants, symptomatology, cytopathology, nucleocapsid composition, serology of their nucleocapsid proteins, and nucleotide sequence homology were compared. The results show that isolates which have previously been discriminated as members of three different serogroups, should in fact be regarded as representatives of at least three distinct virus species in the tospovirus genus.

Blotting, Northern↗
PubMed1993

Classification of tospoviruses based on phylogeny of nucleoprotein gene sequences.

The nucleotide sequences of the nucleoprotein (N) genes of seven tospovirus isolates representing three serogroups were determined and used to establish phylogenetic parameters to delineate species within the Tospovirus genus of the Bunyaviridae. A high sequence divergence (55.9% identity at the nucleotide level) was observed between isolates of serogroup I (tomato spotted wilt virus) and isolates of serogroup III (Impatiens necrotic spot virus). The serogroup II isolates take an intermediate position. Their N genes have 75% identity with those of serogroup I isolates and 57% with those of serogroup III isolates. Whereas the isolates within serogroups I or III have almost identical sequences, the two isolates BR-03 and SA-05 of serogroup II diverged significantly from each other (82.1% sequence identity). The results obtained support the conclusion that, in addition to the species TSWV and INSV, the serogroup II isolates BR-03 and SA-05 have to be considered as distinct species within the genus Tospovirus for which the names tomato chlorotic spot virus and groundnut ringspot virus, respectively, are proposed.

Amino Acid Sequence↗
PubMed1993

Multiplication of tomato spotted wilt virus in its insect vector, Frankliniella occidentalis.

The accumulation of two proteins, the nucleocapsid (N) protein and a non-structural (NSs) protein both encoded by the S RNA of tomato spotted wilt virus (TSWV), was followed in larvae during development and in adults of Frankliniella occidentalis after ingesting the virus for short periods on infected plants. The amounts of both proteins increased, as shown by ELISA and Western blot analysis, within 2 days above the levels ingested, indicating multiplication of TSWV in these insects. Accumulation of these proteins and of virus particles was further confirmed by in situ immunolabelling of the salivary glands and other tissues of adult thrips. The accumulation of large amounts of N and NSs protein, the occurrence of several vesicles with virus particles in the salivary glands and the massive numbers of virus particles in the salivary gland ducts demonstrate that the salivary glands are a major site of TSWV replication. The occurrence of virus particles in the salivary vesicles is indicative of the involvement of the Golgi apparatus in the maturation of the virus particles and its transport to the salivary ducts.

Animals↗
PubMed1993

Structure and function of proteins of the phosphotransferase system and of 6-phospho-beta-glycosidases in gram-positive bacteria.

New information about the proteins of the phosphotransferase system (PTS) and of phosphoglycosidases of homofermentative lactic acid bacteria and related species is presented. Tertiary structures were elucidated from soluble PTS components. They help to understand regulatory processes and PTS function in lactic acid bacteria. A tertiary structure of a membrane-bound enzyme II is still not available, but expression of Gram-positive genes encoding enzymes II can be achieved in Escherichia coli and enables the development of effective isolation procedures which are necessary for crystallization experiments. Considerable progress was made in analysing the functions of structural genes which are in close vicinity of the genes encoding the sugar-specific PTS components, such as the genes encoding the tagatose-6-P pathway and the 6-phospho-beta-glycosidases. These phosphoglycosidases belong to a subfamily of the beta-glycosidase family I among about 300 different glycosidases. The active site nucleophile was recently identified to be Glu 358 in Agrobacterium beta-glucosidase. This corresponds to Glu 375 in staphylococcal and lactococcal 6-phospho-beta-galactosidase. This enzyme is inactivated by mutating Glu 375 to Gln. Diffracting crystals of the lactococcal 6-P-beta-galactosidase allow the elucidation of its tertiary structure which helps to derive the structures for the entire glycosidase family 1. In addition, a fusion protein with 6-phospho-beta-galactosidase and staphylococcal protein A was constructed.

Amino Acid Sequence↗
PubMed1993

Abdominal fat deposition in 11-year-old children.

Although the metabolic complications accompanying visceral deposition of fat are well-established, the onset and extent of such fat patterning in children has not been fully documented. This has been due to the problem of computerized tomography exposing children to a prohibitive radiation risk. Nuclear magnetic resonance imaging (MRI) has provided a feasible alternative. Specifically, the purposes of this study were to use MRI (i) to assess the extent of intra-abdominal (IA) and subcutaneous abdominal (SA) fat deposition in 11-year-old boys and girls, and (ii) to identify the most useful anthropometric indicators of IA adiposity in children. Twenty-five boys and 25 girls were selected to represent, by quintiles, the body mass index range for their age. IA fat, SA fat, and total cross-sectional areas were measured from an MRI scan at the umbilicus. Body density was assessed by hydrostatic weighing, and skinfold thicknesses, circumferences and related ratios, and stage of sexual maturity were measured. Results showed that a wide variation in IA fat deposition was present with amounts ranging from 6 to 58 cm2 (mean = 17.8 +/- 10.0) for boys and 15 to 50 cm2 (mean = 24.8 +/- 8.8) for girls. Percentage of cross-sectional area taken up by visceral fat appears to be less than in normal weight adults. Fourteen children had intra-abdominal/subcutaneous abdominal fat ratios that have been associated with higher health risk in obese adults. Waist-hip circumference ratio (WHR), which is widely used as an indicator of IA deposition in adults, was not a useful predictor in these children.(ABSTRACT TRUNCATED AT 250 WORDS)

Abdomen↗