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Biomedical subjects

R Hull

Publications and source records attributed to R Hull.

At least 91 records · Page 5Linked to original sources
PubMed1993

Paracrystalline structure of cauliflower mosaic virus aphid transmission factor produced both in plants and in a heterologous system and relationship with a solubilized active form.

Cauliflower mosaic virus (CaMV) aphid transmission factor (ATF), produced in a baculovirus expression system, forms paracrystalline structures, as demonstrated by electron microscopic observations. Similar paracrystals were also found in CaMV-infected plants, using immunogold techniques, thus providing the first evidence of such a structure for the CaMV ATF (P18). We demonstrated that the paracrystals can be solubilized to provide an active form of the CaMV ATF which can also be reverted into the paracrystalline aggregated form. This suggests that the paracrystalline structures might act as a source of active CaMV ATF or be the form in which it is stored within the infected cells. A point mutation within the CaMV gene II (which encodes the ATF) leads to the loss of both the paracrystalline structures and the ATF activity. Hence, the paracrystalline structure seems to be a feature of the native (unmodified ) CaMV ATF.

Animals↗
PubMed1993

Mapping the 5'-terminus of rice tungro bacilliform viral genomic RNA.

The initiation site of the major transcript of rice tungro bacilliform virus (RTBV) has been located by mapping the 5' end of the RNA to nucleotides 7404 and 7405 of the RTBV genome using an RNase protection method. This was confirmed by the 5' RACE PCR procedure which mapped the 5' end of the RNA to nucleotide 7405. These results are consistent with data from our analysis of the strong-stop DNA of RTBV. A eukaryotic RNA polymerase II promoter sequence (TATATAA) was located at nucleotide 7373 of RTBV genome which is 31-32 nucleotides upstream from the proposed initiation site of the RTBV transcript.

Base Sequence↗
PubMed1993

Molecular cloning and sequencing of coat protein-encoding cDNA of rice tungro spherical virus--a plant picornavirus.

Rice tungro spherical virus (RTSV) was shown to have three coat protein (CP) species by high resolution NaDodSO4-PAGE and Western blot analyses. The sequence of a coat protein-expressing cDNA clone that was identified and selected from a RTSV cDNA library showed that the insert was composed of 2823 bp with only one large open reading frame (ORF) coding for 941 amino acids. The positions of the three coat proteins were located in the putative polyprotein by N-terminal microsequencing and were shown to start at amino acids 287, 495, and 698 for CP-1, CP-2, and CP-3, respectively. The coat proteins are expressed as a polyprotein at the 5' region of the viral RNA genome, and all are cleaved at glutamine carboxy termini, presumably by picornavirus 3C-type of protease(s). Sequence comparisons of coat proteins revealed that there are high amino acid homologies between CP-2 of RTSV and VP3s of encephalomyocarditis virus (EMCV) and Theiler's murine encephalomyelitis virus (TMEV). These results indicate that RTSV is a plant picornavirus.

Amino Acid Sequence↗
PubMed1993

A strong-stop DNA in rice plants infected with rice tungro bacilliform virus.

A virus-specific small nucleic acid (strong-stop DNA) was identified in rice plants infected with rice tungro bacilliform virus, but not in the virus particles. This nucleic acid was shown to consist of about 595 deoxyribonucleotides with about 70 ribonucleotides covalently linked at the 5' end. Hybridization with sequence-specific oligonucleotides showed that the ribonucleotides were from the plant cytoplasmic tRNA(iMet) sequence. PCR analysis detected hairpin structures at the 3' end of the DNA.

Base Sequence↗
PubMed1993

Duplex ultrasonography for the detection of deep vein thrombi after total hip or knee arthroplasty.

The usefulness of real-time duplex ultrasonography (DU) as a screening test for deep vein thrombosis (DVT) in high-risk patients remains uncertain. To determine the sensitivity and specificity of DU for the detection of DVT, the authors prospectively studied 178 consecutive patients after total hip (n = 113) or total knee (n = 66) arthroplasty. The deep veins from the inguinal ligament to the ankle were examined first by continuous wave and then by pulsed Doppler signals as needed with real-time gray-scale ultrasound imaging using the criteria of vein noncompressibility to define DVT. Ascending contrast venography was performed within twelve hours after DU studies. Venograms and DU were interpreted independently. DU was attempted on 177 lower extremities (2 patients refused) but was judged adequate for interpretation for only 145 (82%). Venography could not be performed for 28 lower extremities and was technically inadequate for 8 studies. The primary analysis included 119 examinations for which adequate DU and ascending venograms were interpreted. DU was positive in 17 of 27 lower extremities with DVT (23 calf, 4 proximal) diagnosed by venography (sensitivity = .63; 95% confidence interval [CI] = .42 to .81), and DU was negative in 85 of 92 lower extremities with normal venograms (specificity = .92; 95% CI = .85 to .97). A secondary analysis of 81 prospectively collected anatomically complete DU studies demonstrated a sensitivity of .80 (95% CI = .56 to .94) and a specificity of .90 (95% CI = .80 to .96).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1992

Characterization of a new kallikrein-like enzyme (KLP-S3) of the rat submandibular gland.

The submandibular gland of the rat contains several enzymes belonging to the kallikrein family. These include tissue kallikrein, antigen gamma (T-kininogenase), esterase B and tonin. In the present study, a new member of this family, which we have named KLP-S3, was identified and purified from the submandibular gland. KLP-S3 was classified as a kallikrein-like enzyme on the basis of its immunological similarity to other kallikrein-like enzymes and its showing 70% and 73% identity in partial amino acid sequence with tissue kallikrein and tonin respectively. Furthermore, the 44 sequenced amino acid residues showed complete correspondence to the mRNA S3 of the kallikrein gene family, which was the rationale for the name kallikrein-like protein (KLP) S3. KLP-S3 consisted of three isoenzymes with pI 6.75, 6.90 and 6.95, which significantly differed from those of other kallikrein-like enzymes. In conjunction with its immunological relationship to kallikrein, this parameter (pI) was considered robust enough to identify the enzyme during purification, since a specific physiological substrate for KLP-S3 has yet to be identified. In SDS/PAGE the three isoenzymes ran as one band with a molecular mass of 25,800 Da, which after reduction with 2-mercaptoethanol was split into two chains with molecular masses of 16,500 and 13,300 Da. In common with other kallikrein-like enzymes, KLP-S3 was inhibited by phenylmethanesulphonyl fluoride, and was thus classified as a serine protease. It was also inhibited by soya-bean trypsin inhibitor but not by aprotinin. It showed weak reactivity against the chromogenic substrates S2288, S2266, S2366 and S2302 (D-Ile-Pro-Arg 4-nitroanilide, D-Val-Leu-Arg 4-nitroanilide, Glu-Pro-Arg 4-nitroanilide and D-Pro-Phe-Arg 4-nitroanilide respectively) and did not cleave rat T-kininogen or dog high-molecular-mass/low-molecular-mass kininogen. Its specific angiotensin II-generating activity (angiotensin I as substrate) was 0.04% of that of rat tonin. KLP-S3 (1-100 nM) induced a statistically significant angiotensin-independent contraction of isolated rat aorta rings. The maximum contraction was 15% of the response to the alpha-adrenoceptor agonist phenylephrine (1 microM). The concentration of KLP-S3 in the rat submandibular gland was by single radial immunodiffusion estimated to be 47 +/- 3 micrograms/mg of protein.

Amino Acid Sequence↗
PubMed1992

Description of an adenovirus type 8 outbreak in hospitalized neonates born prematurely.

An adenovirus (Ad) type 8 outbreak was prospectively studied in a neonatal intensive care unit. Nasopharyngeal secretions were cultured weekly for viruses and clinical information was obtained daily in each infant. Eleven of 112 neonates were infected with Ad; 8 of 9 available isolates represented one variant of Ad 8. The median age at infection was 54 days and the median duration of virus shedding was 2 days. Seven of 11 infants had onset of new symptoms and/or required acute respiratory support; only 2 infants had eye disease. Maternal characteristics, race, gender, age at entry into study and respiratory distress syndrome at birth were similar for both groups. Ad-infected infants tended to have earlier gestations and lower birth weights. Ad-infected neonates stayed longer in the neonatal intensive care unit, required more days of respiratory support and were more likely to develop bronchopulmonary dysplasia. Thus an association was established between lung disease in premature neonates and Ad infection.

Adenovirus Infections, Human↗
PubMed1992

Characterization of the discontinuities in rice tungro bacilliform virus DNA.

The dsDNA of rice tungro bacilliform virus (RTBV) has two discontinuities, one on each strand, each in a specific position as found in other pararetroviruses. The 5' end of discontinuity 1 was mapped to nucleotide 1 of the published RTBV DNA sequence which suggests that tRNAiMet serves as a primer for negative strand DNA synthesis. This 5' terminus contains up to two ribonucleotides and the 3' terminus overlaps it by five to 25 nucleotides. The discontinuity 2 (D2) did not map to a purine-rich region as has been found in other similar viruses. Both the 5' and 3' termini of D2 were heterogeneous in position giving structures varying from a gap of 10 nucleotides to an overlap of 103 nucleotides.

Base Sequence↗
PubMed1992

Expression of cauliflower mosaic virus ORF II in a baculovirus system.

The cauliflower mosaic virus ORF II encoding the aphid transmission factor (ATF) was mutagenized to introduce a BamHI restriction site upstream from the initiation codon and then cloned into an eukaryotic viral expression vector (Autographa californica nuclear polyhedrosis virus). All recombinant viruses tested in Spodoptera frugiperda (SF21) cells expressed a protein of about 18 kD which comigrated in PAGE with ATF from infected plants. Western blotting using an oligopeptide antiserum to ATF confirmed the identity of the 18-kD protein from infected cells as the product of the ORF II sequences (P18). Subcellular fractionation of cells infected with the recombinant AcMNPV demonstrated that the expressed P18 accumulated intracellularly in an insoluble form. Antiserum was produced in rabbit against the partially purified P18 expressed in SF21 cells. When used to immunogold label ultrathin sections of cauliflower mosaic virus (CaMV)-infected turnip tissue, this antiserum was shown to be highly specific, labelling only the electronlucent inclusion bodies (containing P18) and not other plant cellular components.

Animals↗
PubMed1991

An analysis of the sequence of an infectious clone of rice tungro bacilliform virus, a plant pararetrovirus.

The nucleotide sequence of an infectious clone of rice tungro bacilliform virus (RTBV) DNA has been determined. The circular genome has 8002 bp and one strand contains four open reading frames (ORFs). One ORF is potentially capable of encoding a protein of 24 kD (P24) and has no initiation (ATG) codon. The other three ORFs potentially encode proteins of 12 kD, 194 kD and 46 kD (P12, P194, P46) respectively. The functions of P24, P12 and P46 are unknown. Comparative analyses with retroviruses and Commelina yellow mottle virus suggest that the 194 kD putative product is a polyprotein that is proteolytically cleaved to yield the virion coat protein, a protease and replicase (reverse transcriptase and RNase H) characteristic of retroelements. The DNA sequence reveals other features which strongly support our belief that RTBV is a pararetrovirus. These include sequences at the mapped positions of two discontinuities in the virion DNA which are complementary to tRNA metinit and purine-rich, and may be the priming sites for minus- and plus-strand DNA synthesis respectively. As the positions of likely transcriptional signals suggest, a full-length viral transcript is observed by northern analysis. The predicted folding of the 645 bp 5'-region of this RNA resembles that of caulimoviruses. Comparisons with other reverse transcribing elements are discussed.

Amino Acid Sequence↗
PubMed1991

Nucleotide sequence of cDNA encoding the coat protein of beet yellows virus.

A cDNA clone of beet yellows viral RNA expressed the viral coat protein gene in E. coli. The sequence of the 2724 nucleotide insert revealed three open reading frames, the 3' of which was shown to be the coat protein cistron. This cistron is expressed in E. coli, in spite of there being no obvious ribosome binding site upstream.

Amino Acid Sequence↗
PubMed1991

Cauliflower mosaic virus gene II product forms distinct inclusion bodies in infected plant cells.

Turnip leaves infected with the aphid transmissible isolate of cauliflower mosaic virus (CaMV Cabb B-JI) showed two types of virus-containing inclusion bodies (IBs), which differed morphologically and in their protein composition when analyzed by immunogold labeling of ultrathin sections. Vacuolated IBs, typical of CaMV infections, contained P62 (the generally accepted IB protein) but lacked P18 (the aphid transmission factor), while electron-lucent IBs did not contain P62 but were the only detectable sites of P18 accumulation within the infected leaf cells. Both types of inclusions were detected in cells of the epidermis, vascular bundles, mesophyll, and spongy parenchyma. Electron-lucent IBs were not found in the aphid nontransmissible isolates of CaMV, Campbell and CM4-184.

Animals↗
PubMed1991

The tobacco mosaic virus 30K movement protein in transgenic tobacco plants is localized to plasmodesmata.

Transgenic tobacco plants expressing a gene encoding the tobacco mosaic virus (TMV) movement protein (30K) were studied using immunocytochemical techniques. The movement protein was shown to be localized within or on most of the plasmodesmata observed in the transformed plant. These results are consistent with the idea that the movement protein interacts with the plasmodesmata to facilitate the cell-to-cell spread of TMV.

Capsid Proteins↗
PubMed1991

Expression of the tobacco mosaic virus movement protein using a baculovirus expression vector.

A cDNA clone of the tobacco mosaic virus 30K movement protein (MP) gene was constructed and introduced into an Autographa californica nuclear polyhedrosis baculovirus expression vector. Infection of Spodoptera frugiperda cells with the vector resulted in the synthesis of low levels of MP, which was detected by anti-MP serum as two closely related species of Mr approximately 34K and a third species of 32K. The authenticity of the recombinant MP was confirmed by comparison of the protein, on the basis of migration during SDS-PAGE, with authentic MP from several sources. It appeared that the recombinant MP was not modified by N-linked glycosylation, but was phosphorylated. The recombinant MP was produced in both a phosphorylated and an unphosphorylated state and the former species was shown to comigrate with plant-expressed MP during SDS-PAGE.

Animals↗