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Biomedical subjects

R Hull

Publications and source records attributed to R Hull.

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

In vitro inhibition of Helicobacter pylori NCTC 11637 by organic acids and lactic acid bacteria.

In this study the effects of both pH and organic acids on Helicobacter pylori NCTC 11637 were tested. Lactobacillus acidophilus, Lact. casei, Lact. bulgaricus, Pediococcus pentosaceus and Bifidobacterium bifidus were assayed for their lactic acid production, pH and inhibition of H. pylori growth. A standard antimicrobial plate well diffusion assay was employed to examine inhibitory effects. Lactic, acetic and hydrochloric acids demonstrated inhibition of H. pylori growth in a concentration-dependent manner with the lactic acid demonstrating the greatest inhibition. This inhibition was due both to the pH of the solution and its concentration. Six strains of Lact. acidophilus and one strain of Lact. casei subsp. rhamnosus inhibited H. pylori growth where as Bifidobacterium bifidus, Ped. pentosaceus and Lact. bulgaricus did not. Concentrations of lactic acid produced by these strains ranged from 50 to 156 mmol l-1 and correlated with H. pylori inhibition. The role of probiotic organisms and their metabolic by-products in the eradication of H. pylori in vivo remains to be determined.

Acetates↗
PubMed1995

Kallikrein rK10-induced kinin-independent, direct activation of NO-formation and relaxation of rat isolated aortic rings.

1. rK10, a weak T-kininogenase isolated from the rat submandibular gland, is a protein belonging to the rat kallikrein family. In the present work, we have studied the biological effects of rK10 with respect to its ability to alter vascular resistance, either directly like rK9, i.e. another kallikrein-like protein, trypsin and thrombin, or through the release of kinins like tissue kallikrein (rK1). The direct effect was studied by its vasomotor activity on rat isolated aortic rings since this preparation was insensitive to the action of kinins. Its ability to induce altered vascular resistance through kinin-generation was investigated by blood pressure studies in whole animals. The studies were performed in comparison to rK1. 2. Unlike rK1, which induces hypotension when administered intravenously to rats (delta BP = -56 +/- 5 mmHg, 5 micrograms kg-1), rK10 did not have any effect on systemic blood pressure (delta BP = -3 +/- 1, 5 micrograms kg-1, i.v.). 3. rK10 was without effect on uncontracted aortic rings, but showed a concentration-dependent (10(-8)-10(-6) M) relaxant effect on tissue precontracted with phenylephrine (10(-6) M). After removal of endothelial cells, no relaxation was observed. The relaxant response to rK10 was transient. rK1 (with and without endothelium), bradykinin and T-kinin (with endothelium) had no effect on contracted or uncontracted aortic rings. 4. The relaxant effect of rK10 was dependent on its enzymatic activity since preincubation with aprotinin (1.02 mM) significantly reduced vasorelaxation from 74 +/- 4% to 24 +/- 3%. 5. The relaxant effect was not inhibited by the kinin antagonist Hoe 140 (10-7 M; 34 +/- 4% without,versus 30 +/- 2% with Hoe 140), but was totally inhibited by the NO-synthase inhibitor N omega.nitro-L-arginine methyl ester (L-NAME) (2.5 x 10-4 M; 27 +/- 3% without and 2 +/- 1% with L-NAME).6. These results show that rKlO has the ability to induce vascular relaxation by a specific, direct effect on endothelial cell NO-synthesis, dependent on rK1O proteolytic activity, but independent of its ability to generate kinin. This effect, or its T-kininogenase activity in blood, was not sufficient for rK1O to have an effect on peripheral vascular resistance since intravenous injections of rK1O, unlike rKl, did not induce hypotension. Thus, rKlO does not seem to play a role in blood pressure homeostasis but may have a local effect on vascular resistance.

Adrenergic beta-Antagonists↗
PubMed1995

Molecular cloning of Proteus mirabilis uroepithelial cell adherence (uca) genes.

Proteus mirabilis bacteria are a common cause of hospital-acquired urinary tract infection. In a previous study, we described a P. mirabilis fimbrial protein, UCA, that adhered to human uroepithelial cells. Genes sufficient for expression of UCA adherence were cloned into Escherichia coli K-12. E. coli bacteria that contained the uca recombinant plasmid adhered to human uroepithelial cells. In addition, the ucaA gene encoding the structural component of UCA pili was subcloned, and its DNA sequence was determined. Amino acid sequence homology (30 to 50%) was found between mature UcaA protein and pilins from pathogenic bacteria representing several genera, including E. coli F17, G, and type 1C pilins, Haemophilus M43 pilin, and a Bordetella pilin.

Amino Acid Sequence↗
PubMed1994

Replication intermediates of rice tungro bacilliform virus DNA support a replication mechanism involving reverse transcription.

Rice tungro bacilliform virus (RTBV) replication intermediates have been studied in rice plants infected with the virus. Unencapsidated virus-specific molecules were identified which had open circular, linear, supercoiled (SC), strong-stop, single-stranded, linear double-stranded hairpin, and double-stranded with single-stranded extension DNA forms. The structures of these different DNA forms were consistent with the replication model of cauliflower mosaic virus and support other results that reverse transcription is involved in the replication of RTBV. The existence of nonspecific and defective (+)-strand priming is suggested. The relative amount of SC DNAs differs in various tissues of the same plant and in the same tissue at different ages. This indicates host regulation of the virus replication cycle and a feedback regulatory mechanism in controlling the SC DNA level. There are no obvious differences in the composition of the replication intermediates between insect-infected and agroinoculated rice plants.

DNA Replication↗
PubMed1994

Splicing in a plant pararetrovirus.

Analysis of expression in rice cells of plasmids in which an ATG-less chloramphenicol acetyl transferase ORF was placed in frame with the coding sequence of the pararetrovirus rice tungro bacilliform virus (RTBV) ORF IV, and which contained much of the upstream full-length transcript sequence of RTBV, gave evidence to suggest that a splicing event occurred. Reverse transcription/PCR of RNA from transfected protoplasts and from RTBV-infected plants yielded a product which confirmed that the 5' end of ORF IV was spliced in frame to a short ORF (sORF) in the RTBV leader sequence removing an intron of about 6.3 kb. Most of the translation is initiated at the ATG codon in the sORF with only about 10% at the ORF IV ATG codon. The efficiency of splicing appears to be inversely related to the length of the intron. The finding of splicing in a pararetrovirus blurs the differences between them and retroviruses but is in accord with the hypothesis that retroelements acquire genes and sequences which adapt them to specific niches.

Base Sequence↗
PubMed1994

Detection of rice tungro bacilliform virus gene products in vivo.

To study the products of the open reading frames (ORFs) of rice tungro bacilliform virus in rice plants the sequences containing ORFs I (encoding a 24-kDa protein, P24) and IV (P46) and the protease and polymerase (reverse transcriptase+RNaseH) domains of ORF III were cloned into a pGEX expression vector. The proteins, which were C-terminal fusions to glutathione S-transferase, were expressed in Escherichia coli and antisera were raised against them which, together with an antiserum against virus particles, was used to probe blots of proteins from infected and uninoculated plants and from virus preparations. The P24 antiserum detected virus-specific proteins of 74, 60, and 52 kDa, which are much bigger than expected. These proteins were found in virus preparations and immunogold labeling suggested that they might be internal in the particles. Virus-specific proteins of 33, 37, 62, and > 150 kDa were revealed by antiserum to virus particles. The antiserum to the protease revealed proteins of 13.5, 37, and 68 kDa both in extracts from infected plants and in purified virus preparations. This antiserum decorated intact virus particles as did the particle antiserum. The polymerase domain antiserum reacted with products of 56, 65, and 68 kDa in extracts from infected plants but not in virus particles. The antiserum to the ORF IV product did not detect any bands in either infected plant extracts or virus preparations. The significance of these products is discussed.

Aspartic Acid Endopeptidases↗
PubMed1994

Sequence analysis of rice hoja blanca virus RNA 3.

RNA 3 of rice hoja blanca tenuivirus (RHBV) has 2299 nucleotides and resembles RNA 3 of other tenuiviruses such as maize stripe (MStV) and rice stripe (RStV) viruses in potentially coding with an ambisense strategy for two proteins. Both the viral-sense protein of 23K and the complementary-sense protein of 35K have about 46% amino acid identity with the analogous proteins encoded by RNA 3 of MStV and RStV. As the proteins of MStV and RStV have about 65% identity between themselves, RHBV cannot be a South and Central American strain of the Asian RStV. The intergenic region resembles those of other tenuiviruses, being rich in A and U residues, but its predicted folding pattern is unlike those of other tenuiviruses. Instead, the predicted folding of the intergenic region was indistinguishable from that of the coding regions and there was no evidence for a distinct hairpin-loop structure. The significance to the evolution of tenuiviruses of the similarities that the two proteins have with their analogues in other tenuiviruses is discussed.

Amino Acid Sequence↗
PubMed1993

A comparison of subcutaneous low-molecular-weight heparin with warfarin sodium for prophylaxis against deep-vein thrombosis after hip or knee implantation.

BACKGROUND: Deep-vein thrombosis is a potentially life-threatening complication of total hip or knee replacement. There are few data on the effectiveness and safety of warfarin as compared with low-molecular-weight heparin as prophylaxis against this problem. METHODS: We therefore performed a randomized, double-blind trial in 1436 patients to evaluate the effectiveness and safety of low-molecular-weight heparin (given subcutaneously once daily) as compared with adjusted-dose warfarin to prevent venous thrombosis after hip or knee replacement. Treatment with the drugs was started postoperatively. The primary end point was deep-vein thrombosis as detected by contrast venography (performed a mean of 9.4 days after surgery in each group). RESULTS: Among the 1207 patients with interpretable venograms, 231 of 617 patients (37.4 percent) in the warfarin group and 185 of 590 patients (31.4 percent) in the low-molecular-weight-heparin group had deep-vein thrombosis (P = 0.03). The reduction in risk with low-molecular-weight heparin as compared with warfarin was 16 percent, and the absolute difference in the incidence of venous thrombosis was 6 percent in favor of low-molecular-weight heparin (95 percent confidence interval, 0.8 to 11.4 percent). The incidence of major bleeding was 1.2 percent (9 of 721 patients) in the warfarin group and 2.8 percent (20 of 715 patients) in the low-molecular-weight-heparin group (P = 0.04), and the absolute difference was 1.5 percent in favor of warfarin (95 percent confidence interval, 0.1 to 3.0 percent). CONCLUSIONS: Our data demonstrate that the small reduction in the incidence of venous thrombosis with low-molecular-weight heparin, as compared with warfarin, was offset by an increase in bleeding complications. Although the use of low-molecular-weight heparin is simpler, because it is administered subcutaneously without the need for monitoring, it may be more costly than warfarin. Warfarin is inexpensive, but the overall cost of its use is increased by the need to monitor the intensity of anticoagulation. At this time it is unclear which of these approaches is the most cost effective.

Administration, Oral↗
PubMed1993

Transcoronary cardiac pacing during myocardial ischemia.

Severe bradyarrhythmias are a rare but potentially life threatening complication of percutaneous transluminal coronary angioplasty (PTCA). Previous work has outlined a technique for coronary pacing using the angioplasty guidewire. To examine the effectiveness of this technique during severe ischemia, seven swine underwent placement of an unmodified 0.014 inch angioplasty guidewire and 3.0 mm balloon catheter in the left anterior descending (LAD) artery. Baseline pacing thresholds were obtained. Pacing was begun at twice diastolic threshold and ischemia was produced by balloon inflation. Repeat capture thresholds were obtained after 1 and 8 minutes of ischemia. Transcoronary pacing was successfully performed in all seven animals and was continued for a mean of 13.8 +/- 1.5 minutes. The baseline capture threshold was 4.0 +/- 0.5 mA. The mean capture threshold was 3.3 +/- 0.3 mA and 4.5 +/- 0.9 mA at 1 and 8 minutes of ischemia, respectively. We conclude that transcoronary pacing using the angioplasty guidewire can be successfully performed during myocardial ischemia and may serve as a reliable backup system during interventional procedures complicated by bradyarrhythmias.

Angioplasty, Balloon, Coronary↗
PubMed1993

Itraconazole affects single-dose terfenadine pharmacokinetics and cardiac repolarization pharmacodynamics.

The object of this study was to examine prospectively the effects of itraconazole on the pharmacokinetics and electrocardiographic repolarization pharmacodynamics (QTc intervals) of single-dose terfenadine in six healthy volunteers. It was designed as a prospective cohort study with each subject serving as his own control, set in an outpatient cardiology clinic. The participants were six healthy volunteers (two men, four women; ages 24-35) not taking any prescription or over-the-counter medications. Single-dose terfenadine administration (120 mg) was accompanied by pharmacokinetic profiles and serial determination of the QTc interval for 12 hours. The subjects then began daily oral itraconazole (200 mg each morning) for 7 days. Repeat pharmacokinetic and pharmacodynamic determinations were made after administration of a second dose (120 mg) of terfenadine while receiving itraconazole. The main outcome measures were terfenadine and acid metabolite serum concentrations; corrected QT intervals as determined by 12-lead electrocardiogram (ECG); and presence or absence of late potentials as determined by signal-averaged ECGs over 150 cardiac cycles. There were significant changes in the pharmacokinetic parameters of acid metabolite after treatment with itraconazole. All subjects had detectable levels of unmetabolized terfenadine after addition of itraconazole, which was associated with QT prolongation. There was no evidence of late depolarization as manifested by an increase in QRS duration found using signal-averaged electrocardiography. Itraconazole influences the metabolism of terfenadine in normal volunteers and results in the accumulation of unmetabolized parent drug associated with altered cardiac repolarization. This drug combination should be avoided.

Adult↗
PubMed1993

Biological activity of cauliflower mosaic virus aphid transmission factor expressed in a heterologous system.

Aphid transmission factor (ATF) activity of cauliflower mosaic virus (CaMV) gene II product was recovered after expression of the gene by a baculovirus recombinant. The expression product, when first acquired by aphids through parafilm membrane, was able to mediate the transmission of two aphid nontransmissible isolates (CM1841, CM4-184) providing the first direct evidence that the product of the gene II is the CaMV ATF. The CaMV ATF in its active conformation has a strong tendency to aggregate and all attempts at solubilizing it resulted in the loss of the ATF activity. The CaMV ATF was also expressed in Escherichia coli, using the pGEX 3X plasmid vector, as a fusion protein to glutathione S-transferase (GST) and was purified. The fusion product (GST-P18), whether purified or not, was not able to complement the transmission of transmission-defective isolates. However, when GST-P18 was added to some extracts from a plant infected with an aphid-transmissible isolate (Cabb B-JI), the transmission was inhibited. This suggests that it could be possible to block the in vitro transmission of CaMV using a molecule analogous to the ATF.

Amino Acid Sequence↗
PubMed1993

Gene II product of an aphid-nontransmissible isolate of cauliflower mosaic virus expressed in a baculovirus system possesses aphid transmission factor activity.

A new baculovirus expression system was used to express the gene II which encodes the 18-kDa aphid transmission factor (ATF) protein of two isolates of cauliflower mosaic virus (CaMV), the aphid-transmissible (AT+) Cabb B-JI and the aphid-nontransmissible (AT-) CM1841 isolates. ATF activity was shown to be associated with the baculovirus expression product of CaMV gene II from both the AT+ and the AT- isolates. No differences could be detected in the stability of the P18s from AT+ and AT- isolates expressed in the baculovirus system. These results indicate that the AT- phenotype of CM1841 isolate might not be due to a defective P18 but to an insufficient concentration of it in infected plant tissue.

Animals↗
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↗