PubMed Health⌕ Search

Biomedical subjects

R Hull

Publications and source records attributed to R Hull.

At least 19 recordsLinked to original sources
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↗
PubMed1991

Rice tungro bacilliform virus DNA independently infects rice after Agrobacterium-mediated transfer.

In nature, rice tungro disease is caused by an RNA and a DNA virus complex, but we have obtained an independently infectious clone of rice tungro bacilliform virus (RTBV) DNA. Infectivity could be demonstrated only when a more than unit-length copy was cloned in the Agrobacterium binary vector Bin 19 and agroinoculated into rice plants. Rice plants thus agroinfected with cloned RTBV DNA showed typical symptoms of tungro disease, presence of viral DNA and bacilliform particles, and could be used as a source of virus to infect healthy plants by the green leafhopper (Nephotettix virescens). The importance of this infectious clone in understanding the molecular biology of RTBV and the rice tungro disease is discussed.

DNA, Viral↗
PubMed1991

Persistence of Escherichia coli bacteriuria is not determined by bacterial adherence.

The role of bacterial adherence in the persistence of bacteria in the human urinary tract was analyzed. Women with chronic symptomatic urinary tract infections were subjected to deliberate colonization with nonvirulent Escherichia coli, after eradication of their current infections. E. coli organisms were instilled into the bladder through a catheter. The strain used for colonization, E. coli 83972, was isolated from a patient with stable bacteriuria. It lacked expressed adherence factors and did not belong to the uropathogenic O:K:H serotypes. Strain 83972 was transformed with the pap and pil DNA sequences encoding Gal alpha 1-4Gal beta- and mannose-specific (type 1) adhesins. Patients were colonized with a mixture of the wild-type and the transformed strains. E. coli 83972 caused stable bacteriuria for greater than 30 days in 7 of 12 individuals. In contrast, the Gal alpha 1-4 Gal beta-recognizing or mannose-binding transformants were eliminated within 48 h. The consistent superiority of the wild-type strain in establishing stable bacteriuria when compared with the adhesive transformants did not appear to be due to differences in growth rates or to plasmid segregation. Rather, the transformants expressing the adhesin determinants were selectively eliminated by the host. This suggested that the acquisition of adherence factors is not sufficient to increase the fitness of E. coli for survival in the urinary tract of humans.

Adult↗