Noninvasive pacing: what you should know

Noninvasive pacing is a valuable therapy in emergency cardiac care. The more experience clinicians have with the noninvasive pacing procedure, the greater their confidence and the easier the job becomes. Effective troubleshooting during pacing becomes less problematic with increased experience with the therapy. Noninvasive pacing allows rapid initiation of emergency pacing and "buys time" to stabilize the patient and plan further care.

A randomized trial of three iron dextran infusion methods for anemia in EPO-treated dialysis patients

Forty-three hemodialysis patients receiving recombinant erythropoietin (rHuEPO, epoietin alpha) were randomized to receive intravenous iron dextran as a total-dose infusion, 500-mg infusion to total dose, or 100-mg bolus to total dose, in each case during the dialysis procedure. The dose of iron dextran was calculated from the patient's existing hemoglobin to achieve a desired hemoglobin. Patients were eligible to receive intravenous iron dextran if they had a serum ferritin of < or = 100 ng/mL or a serum ferritin of 100 to 200 ng/mL, along with a transferrin saturation of < or = 19%. Patients were excluded if they had prior therapy with iron dextran, aluminum intoxication, or transfusion during the study. The time to the maximum hemoglobin, acute adverse reactions, and delayed adverse reactions were analyzed statistically, and no differences were seen in any of the three groups. Total-dose intravenous iron dextran infusion is safe, convenient, less expensive, and as efficacious as divided-dose infusions.

Conformation of the 3'-end of beet necrotic yellow vein benevirus RNA 3 analysed by chemical and enzymatic probing and mutagenesis

Secondary structure-sensitive chemical and enzymatic probes have been used to produce a model for the folding of the last 68 residues of the 3'-non-coding region of beet necrotic yellow vein benevirus RNA 3. The structure consists of two stem-loops separated by a single-stranded region. RNA 3-derived transcripts were produced containing mutations which either disrupted base pairing in the helices or maintained the helices but with alterations in the base pairing scheme. Other mutants contained substitutions in single-stranded regions (loops or bulged sequences). With a few exceptions all three types of mutation abolished RNA 3 replication in vivo, suggesting that both secondary structure and specific sequences are required for efficient recognition of the 3'-terminal region of RNA 3 by viral RNA-dependent RNA polymerase.

BIM1 encodes a microtubule-binding protein in yeast

A previously uncharacterized yeast gene (YER016w) that we have named BIM1 (binding to microtubules) was obtained from a two-hybrid screen of a yeast cDNA library using as bait the entire coding sequence of TUB1 (encoding alpha-tubulin). Deletion of BIM1 results in a strong bilateral karyogamy defect, hypersensitivity to benomyl, and aberrant spindle behavior, all phenotypes associated with mutations affecting microtubules in yeast, and inviability at extreme temperatures (i.e., >/=37 degrees C or Collapse

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MESH Headings

• Alleles
• Amino Acid Sequence
• Cell Cycle
• Cell Cycle Proteins/chemistry
• Cell Cycle Proteins/genetics
• Cell Cycle Proteins/metabolism
• Cell Nucleus/chemistry
• Cell Nucleus/metabolism
• Cell Size
• Cytoskeleton/chemistry
• Cytoskeleton/genetics
• Cytoskeleton/metabolism
• Fungal Proteins/chemistry
• Fungal Proteins/genetics
• Fungal Proteins/metabolism
• Genes, Fungal/genetics
• Genes, Fungal/physiology
• Genes, Lethal/genetics
• Humans
• Microtubule Proteins/chemistry
• Microtubule Proteins/genetics
• Microtubule Proteins/metabolism
• Microtubule-Associated Proteins/chemistry
• Microtubules/chemistry
• Microtubules/genetics
• Microtubules/metabolism
• Molecular Sequence Data
• Mutation/genetics
• Nuclear Proteins/chemistry
• Nuclear Proteins/genetics
• Nuclear Proteins/metabolism
• Phenotype
• Protein Binding
• Recombinant Fusion Proteins/chemistry
• Recombinant Fusion Proteins/genetics
• Recombinant Fusion Proteins/metabolism
• Saccharomyces cerevisiae/cytology
• Saccharomyces cerevisiae/genetics
• Saccharomyces cerevisiae Proteins
• Spindle Apparatus/chemistry
• Spindle Apparatus/metabolism
• Tubulin/chemistry
• Tubulin/genetics
• Tubulin/metabolism
• Two-Hybrid System Techniques

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Grants

• R01 GM046406 NIGMS NIH HHS
• R37 GM046406 NIGMS NIH HHS
• GM-46406 NIGMS NIH HHS

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The N-terminal region of the luteovirus readthrough domain determines virus binding to Buchnera GroEL and is essential for virus persistence in the aphid

Luteoviruses and the luteovirus-like pea enation mosaic virus (PEMV; genus Enamovirus) are transmitted by aphids in a circulative, nonreplicative manner. Acquired virus particles persist for several weeks in the aphid hemolymph, in which a GroEL homolog, produced by the primary endosymbiont of the aphid, is abundantly present. Six subgroup II luteoviruses and PEMV displayed a specific but differential affinity for Escherichia coli GroEL and GroEL homologs isolated from the endosymbiotic bacteria of both vector and nonvector aphid species. These observations suggest that the basic virus-binding capacity resides in a conserved region of the GroEL molecule, although other GroEL domains may influence the efficiency of binding. Purified luteovirus and enamovirus particles contain a major 22-kDa coat protein (CP) and lesser amounts of an approximately 54-kDa readthrough protein, expressed by translational readthrough of the CP into the adjacent open reading frame. Beet western yellows luteovirus (BWYV) mutants devoid of the readthrough domain (RTD) did not bind to Buchnera GroEL, demonstrating that the RTD (and not the highly conserved CP) contains the determinants for GroEL binding. In vivo studies showed that virions of these BWYV mutants were significantly less persistent in the aphid hemolymph than were virions containing the readthrough protein. These data suggest that the Buchnera GroEL-RTD interaction protects the virus from rapid degradation in the aphid. Sequence comparison analysis of the RTDs of different luteoviruses and PEMV identified conserved residues potentially important in the interaction with Buchnera GroEL.

Standards and practice guidelines as the foundation for clinical practice

The structure and organization of health care delivery are in the midst of rapid change. Health care providers from a variety of disciplines are being challenged to define their practice and the expected patient outcomes resulting from their processes of care delivery. Standards and clinical practice guidelines are important tools for enhancing the quality of health care delivery and for documenting care. The article describes a process for developing standards and clinical practice guidelines and presents an organizational scheme for them. Based on recommendations from diverse national groups, a format for practice guidelines is presented, and a system for implementation and ongoing evaluation is recommended.

Effects of mutations in the beet western yellows virus readthrough protein on its expression and packaging and on virus accumulation, symptoms, and aphid transmission

Virions of beet western yellows luteovirus contain a major capsid protein (P22.5) and a minor readthrough protein (P74), produced by translational readthrough of the major capsid protein sequence into the neighboring open reading frame, which encodes the readthrough domain (RTD). The RTD contains determinants required for efficient virus accumulation in agroinfected plants and for aphid transmission. The C-terminal halves of the RTD are not well conserved among luteoviruses but the N-terminal halves contain many conserved sequence motifs, including a proline-rich sequence separating the rest of the RTD from the sequence corresponding to the major coat protein. To map different biological functions to these regions, short in-frame deletions were introduced at different sites in the RTD and the mutant genomes were transmitted to protoplasts as transcripts and to Nicotiana clevelandii by agroinfection. Deletions in the nonconserved portion of the RTD did not block aphid transmission but had a moderate inhibitory effect on virus accumulation in plants and abolished symptoms. Deletion of the proline tract and the junction between the conserved and nonconserved regions inhibited readthrough protein accumulation in protoplasts by at least 10-fold. The mutants accumulated small amounts of virus in plants, did not induce symptoms, and were nontransmissible by aphids using agroinfected plants, extracts of infected protoplasts, or purified virus as a source of inoculum. Other deletions in the conserved portion of the RTD did not markedly diminish readthrough protein accumulation but abolished its incorporation into virions. These mutants accumulated to low levels in agroinfected plants and elicited symptoms, but could not be aphid-transmitted. A preliminary map has been produced mapping these functions to different parts of the RTD.

High resolution analysis of the readthrough domain of beet necrotic yellow vein virus readthrough protein: a KTER motif is important for efficient transmission of the virus by Polymyxa betae

The 5'-terminal cistron of beet necrotic yellow vein furovirus RNA 2 encodes the 21 kDa major viral coat protein and terminates with an amber stop codon which can undergo suppression to give rise to a 75 kDa readthrough (RT) protein referred to as P75. P75 is a minor component of virions and the 54 kDa RT domain following the coat protein sequence is important both for virus assembly and transmission by the fungal vector Polymyxa betae. To better define the regions of the RT domain involved in these two steps, RNA 2 transcripts encoding different in-frame RT domain deletion mutants were tested for their ability to form virions when inoculated to plants with the other viral RNAs and to be fungus-transmitted. All deletions in the N-terminal half of the RT domain interfered with virus assembly and partially or completely inhibited fungus transmission. A 4 1 1 nucleotide deletion within the C-terminal half of the RT domain did not inhibit assembly but blocked fungus transmission of the virus. Alanine scanning mutagenesis within the aforesaid 4 1 1 nucleotide subdomain identified a peptide motif (KTER) which is important for the fungus transmission process.

Occupational exposure to metal or wood dust and aetiology of cryptogenic fibrosing alveolitis

BACKGROUND

We have previously suggested that cryptogenic fibrosing alveolitis (CFA) may be caused by occupational exposures, particularly to metal or wood dust. We have specifically investigated this hypothesis in a case-control study of patients with CFA.

METHODS

We obtained lifetime occupational histories by postal questionnaire from 218 patients with CFA and 569 controls matched for age, sex, and community, living in the Trent region of the UK. Information was subsequently verified by telephone interview in 165 cases and 408 controls. Serum IgE, rheumatoid factor, and antinuclear antibodies and skin sensitivity to common allergens were measured in cases and in one matched control for each.

FINDINGS

The relative risk of CFA, after adjustment for smoking, was significantly increased in relation to questionnaire-reported exposure to metal dust (odds ratio 1.68 [95% CI 1.07-2.65], p = 0.024) or to wood dust (1.71 [1.01-2.92], p = 0.048). Similar results were obtained with the telephone interview data. Significant exposure-response effects were found for both metal-dust and wood-dust exposure. CFA was also associated with the presence of rheumatoid factor or antinuclear antibodies, but not with positive allergen skin tests or raised IgE concentrations. There was no evidence of interaction between the effects of rheumatoid factor, antinuclear antibodies, positive skin allergen tests, or IgE concentrations and exposure to metal or wood dust. The combined aetiological fraction attributable to exposure to metal or wood dust was of the order of 20%.

INTERPRETATION

Occupational exposures to metal or wood dust are independent risk factors for CFA. Avoidance or limitation of these exposures may provide an opportunity to prevent the disease.

A cross sectional study of the independent effect of occupation on lung function in British coal miners

BACKGROUND

Chronic bronchitis and emphysema are now recognised complications of occupational exposure to coal dust, and since 1992 compensation has been available for miners with impaired lung function provided that they also have x ray film evidence of pneumoconiosis. However, many miners with heavy exposure to coal dust and impairment of lung function therefore do not qualify for compensation because they do not have simple pneumoconiosis. In the present study attempts were made to determine whether coal mining is an independent risk factor for impairment of lung function in a group of Nottinghamshire miners with no evidence of simple pneumoconiosis, by comparing these men with a group of local controls who were not occupationally exposed.

METHOD

Forced expiratory volume in one second (FEV1) and forced vital capacity (FVC) were obtained on 1286 miners with no evidence of pneumoconiosis on x ray film. Lung function data were also obtained from a random sample of 567 men aged between 40 and 70 living in a district of Nottingham and who had never worked in the mining industry or in any other dusty occupation. Multiple linear regression in SPSS was used to estimate the mean independent effect of mining on FEV1 and FVC after adjustment for age, height, and smoking, in all miners and controls, and in a subgroup of men of 45 and under. In men of 45 and under, the independent effects of mining and smoking on the probability of a deficit of one litre or more from modelled predicted FEV1 values were computed with logistic regression in EGRET.

RESULTS

There was a significant mean effect of mining on FEV1 after adjustment for age, height, and smoking of -155 ml (95% confidence interval (95% CI) -74 to -236 ml, P < 0.001), but the size of effect was inversely related to age such that in men of 45 and under the estimated mean effect of mining was -251 ml (95% CI -140 to -361 ml, P < 0.001). In this subgroup of younger men, 4.7% of miners and 0.7% of controls had a deficit of one litre or more from predicted FEV1 values, and in logistic regression, there was a marginally significant independent effect of both smoking (P = 0.05) and mining (P = 0.07) for a deficit of this magnitude.

CONCLUSIONS

Occupational exposure to coal dust is associated with a small mean deficit in lung function even in the absence of simple pneumoconiosis, and independently from the effects of smoking. The requirement that miners should have evidence of pneumoconiosis to qualify for compensation for impaired lung function is therefore unjustified.

Synthesis of a full-length infectious cDNA clone of cucurbit aphid-borne yellows virus and its use in gene exchange experiments with structural proteins from other luteoviruses

A full-length cDNA of cucurbit aphid-borne yellows virus (CABYV) has been constructed and expressed either as an in vitro transcript, under control of a bacteriophage T7 RNA polymerase promoter, or in vivo, under control of the cauliflower mosaic virus 35S promoter in an agroinfection vector. The biological activity of the cloned cDNA was demonstrated by the ability of its in vitro transcript to replicate in protoplasts and of the agroinfection vector to infect agroinoculated plants. Virus in the agroinfected plants cold be transmitted by the aphid vectors Myzus persicae and Aphis gossypii. The specificity of luteovirus RNA packaging was investigated by replacing (1) the CABYV coat protein gene (and the overlapping ORF5) by the corresponding region of potato leafroll luteovirus or (2) the CABYV readthrough domain by the readthrough domain of beet western yellows luteovirus. The resulting chimeric transcripts replicated in protoplasts and produced virions.

The small cysteine-rich protein P14 of beet necrotic yellow vein virus regulates accumulation of RNA 2 in cis and coat protein in trans

The effect of null mutations of the small cysteine-rich protein P14 encoded by RNA 2 of beet necrotic yellow vein virus has been investigated using in vitro transcripts of viral RNA to infect Chenopodium quinoa protoplasts. The P14 mutations down-regulated RNA 2 accumulation by approximately 10- to 50-fold. Accumulation of minus-strand RNA 2 was also diminished but RNA 1 accumulation was much less affected. The inhibition of RNA 2 accumulation could not be complemented in trans by providing P14 from another source (either a second molecule of RNA 2 or an RNA 3-based replicon) containing and expressing the P14 gene. The P14 null mutations dramatically inhibited accumulation of viral coat protein, which is encoded by the 5'-proximal gene on RNA 2, but this effect could be complemented in trans, indicating that it occurs by a mechanism distinct from that affecting RNA 2 accumulation. Transient expression experiments were also carried out in which a plasmid expressing P14 and plasmids expressing a reporter gene placed downstream of potential translational control sequences (the 5'-noncoding sequences of RNAs 2, 3, or 4) were introduced into C. quinoa or Nicotiana tabacum leaves by microprojectile bombardment. Coexpression of P14 produced a 3- to 4-fold stimulation of reporter gene expression levels for all the constructs. The lack of sequence specificity suggests that this phenomenon is not directly related to the RNA 2-specific stimulation of coat protein accumulation observed in a viral infection.

Aphid transmission of beet western yellows luteovirus requires the minor capsid read-through protein P74

Beet western yellows luteovirus is obligately transmitted by the aphid Myzus persicae in a circulative, non-propagative fashion. Virus movement across the epithelial cells of the digestive tube into the hemocoel and from the hemocoel into the accessory salivary glands is believed to occur by receptor-mediated endocytosis and exocytosis. Virions contain two types of protein; the major 22 kDa capsid protein and the minor read-through protein, P74, which is composed of the major capsid protein fused by translational read-through to a long C-terminal extension called the read-through domain. Beet western yellows virus carrying various mutations in the read-through domain was tested for its ability to be transmitted to test plants by aphids fed on agro-infected plants and semi-purified or purified virus preparations. The results establish that the read-through domain carries determinants that are essential for aphid transmission. The findings also reveal that the read-through domain is important for accumulation of the virus in agro-infected plants.

Complete nucleotide sequence of peanut clump virus RNA 1 and relationships with other fungus-transmitted rod-shaped viruses

The complete nucleotide sequence of RNA 1 of the tentative furovirus peanut clump virus (PCV) has been determined by characterization of cloned cDNA and by direct RNA sequencing. The sequence is 5897 nucleotides in length and contains three long open reading frames (ORFs). The 5'-terminal proximal ORF has the potential to encode a polypeptide of M(r) 130942 (P131) containing methyltransferase and RNA helicase homologous domains and displaying homology with large nonstructural proteins of alpha-like viruses, which are known or thought to be involved in virus replication. The P131 ORF is followed in-frame by a second ORF which is probably expressed by partial readthrough of the UGA termination codon of the P131 ORF to produce a polypeptide of M(r) 191044 (P191). The readthrough region of P191 contains the characteristic 'core' RNA polymerase motif, indicating that the PCV replicase proteins are expressed as a pair of overlapping proteins as in the tobamoviruses, tobraviruses and the furovirus soil-borne wheat mosaic virus (SBWMV). Sequence comparisons indicate that P131 and P191 are most closely related to the replicase proteins of SBWMV and the hordeivirus barley stripe mosaic virus (BSMV) but are only distantly related to the replicase of the furovirus beet necrotic yellow vein virus (BNYVV). The 3'-terminal proximal ORF can encode a putative polypeptide of M(r) 14556 (P15) which displays homology to small cysteine-rich proteins of hordeiviruses and SBWMV. We have corrected four errors in the sequence of PCV RNA 2 published previously by Manohar et al. (Virology 195, 33-41, 1993). One of these changes causes two small ORFs near the 3' terminus of RNA 2 to be fused together to create an ORF for a putative polypeptide of M(r) 16833 (P17) which displays extensive homology with the third protein of the triple gene block of BSMV RNA beta.

Dietary sodium intake and the risk of airway hyperreactivity in a random adult population

BACKGROUND

High dietary sodium intake has been identified as a potential cause of asthma and airway hyperreactivity. This study was designed to test the hypothesis that dietary sodium intake is an independent determinant of the risk of hyperreactivity in the general population, and to assess the role of atopy in the association between these factors.

METHODS

Airway reactivity to methacholine, atopy, 24 hour urinary sodium excretion, and self-reported smoking and symptom history were measured in a random sample of 1702 adults aged 18-70 from an administrative district of Nottingham. Hyperreactivity was defined as a PD20FEV1 of 12.25 mumol or less, and atopy was defined quantitatively as the mean allergen skin weal response to Dermatophagoides pteronyssinus, cat fur, and grass pollen, and categorically as the occurrence of any allergen response 1 mm or greater than the saline control. Multiple logistic regression analysis was used to estimate the independent relative odds of hyperreactivity, atopy, or symptoms in relation to sodium excretion in all 1702 subjects, and multiple linear regression to assess the independent relation between sodium excretion and mean allergen skin weal diameter, and the PD20 value amongst hyperreactive subjects.

RESULTS

There was no relation between the relative odds of hyperreactivity to methacholine and 24 hour urinary sodium excretion, either before or after adjustment for age, smoking, allergen skin weal diameter, and sex, and similarly no relation if the analysis was restricted to men or women only. The relative odds of having at least one allergen skin test response 1 mm greater than the saline control were increased in relation to sodium excretion after adjustment for age, sex, and smoking by a ratio of 2.08 (95% CI 1.04 to 4.15) per log10 unit increase in sodium excretion, but there was no evidence of an association between sodium excretion and the occurrence of self-reported wheeze, hay fever, eczema, or asthma. There was no relation between 24 hour sodium excretion and the magnitude of the mean allergen skin weal response or the PD20 value.

CONCLUSIONS

These findings do not support the hypothesis that a high dietary sodium intake is a risk factor for airway hyperreactivity or atopic disease in the general adult population.

Dietary magnesium, lung function, wheezing, and airway hyperreactivity in a random adult population sample

Magnesium is involved in a wide range of biological activities, including some that may protect against the development of asthma and chronic airflow obstruction. We tested the hypothesis that high dietary magnesium intake is associated with better lung function, and a reduced risk of airway hyper-reactivity and wheezing in a random sample of adults. In 2633 adults aged 18-70 sampled from the electoral register of an administrative area of Nottingham, UK, we measured dietary magnesium intake by semiquantitative food-frequency questionnaire, lung function as the 1-sec forced expiratory volume (FEV1), and atopy as the mean skin-prick test response to three common environmental allergens. We measured airway reactivity to methacholine in 2415 individuals, defining hyper-reactivity as a 20% fall in FEV1 after a cumulative dose of 12.25 mumol or less. Mean (SD) daily intake of magnesium was 380 (114) mg/day. After adjusting for age, sex, and height, and for the effects of atopy and smoking, a 100 mg/day higher magnesium intake was associated with a 27.7 (95% CI, 11.9-43.5) mL higher FEV1, and a reduction in the relative odds of hyper-reactivity by a ratio of 0.82 (0.72-0.93). The same incremental difference in magnesium intake was also associated with a reduction in the odds of self-reported wheeze within the past 12 months, adjusted for age, sex, smoking, atopy, and kilojoule intake, by a ratio of 0.85 (0.76-0.95). Dietary magnesium intake is independently related to lung function and the occurrence of airway hyper-reactivity and self-reported wheezing in the general population. Low magnesium intake may therefore be involved in the aetiology of asthma and chronic obstructive airways disease.

Nucleotide sequence of cucurbit aphid-borne yellows luteovirus

The nucleotide sequence (5669 residues) of the genomic RNA of cucurbit aphid-borne yellows luteovirus (CABYV) is presented. Analysis of genome organization and sequence homologies indicate that CABYV is a member of luteovirus Subgroup 2 (other sequenced members: beet western yellows virus, potato leafroll virus, and barley yellow dwarf virus, RPV isolate) and appears to be most closely related to beet western yellows virus.

Production of extracellular slime by coryneforms colonizing hydrocephalus shunts

Corynebacterium spp. are responsible for an important minority of cases of colonization of cerebrospinal fluid shunts used for the treatment of hydrocephalus. In common with coagulase-negative staphylococci, they present a serious therapeutic problem because they are often resistant to multiple antibiotics. We studied the morphologies of coryneforms in colonized hydrocephalus shunts removed from patients and observed extracellular slime similar in appearance to that seen in coagulase-negative staphylococci. We also studied a series of such isolates from other cases of hydrocephalus shunt colonization using an established laboratory model and consistently observed slime production in these shunts as well. We propose that this might be a further reason for failure to eradicate these organisms without shunt removal as well as a factor in their pathogenesis in device-related infections.

Factors influencing the occurrence of airway hyperreactivity in the general population: the importance of atopy and airway calibre

The factors that determine the occurrence of airway hyperreactivity in the general population are not clearly understood. This study was designed to assess the independent effects of age, atopy, smoking and airway calibre. In a random sample of 2,415 adults aged 18-70 yrs we measured reactivity to methacholine as the dose provoking a 20% fall (PD20) in one-second forced expiratory volume (FEV1), atopy as the mean skin wheal response to three common environmental allergens, and airway calibre as the baseline FEV1 in absolute terms, as percent predicted (FEV1 % predicted) and as percent forced vital capacity (FEV1 % FVC). Hyperreactivity, defined as a PD20 < or = 12.25 mumol, was present in 314 (13%) of the sample, and before adjustment for FEV1 was more common in females (independent odds ratio (OR) = 2.05 (95% confidence interval 1.6-2.7)), current smokers (OR = 1.89 (1.3-2.6)), atopics (OR = 1.39 (1.3-1.5) per mm skin wheal), and in older age groups (OR for age 60-70 yrs relative to 18-29 yrs = 2.70 (1.7-4.3)). However, the odds of hyperreactivity were also strongly and independently related to absolute FEV1 (OR = 0.46 (0.27-0.77) per litre), FEV1 % predicted (OR = 0.96 (0.94-0.98) per percent), and FEV1 % FVC (OR = 0.92 (0.90-0.94) per percent; combined chi-square on 3 df = 312, p << 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS)

Factors influencing the occurrence of airway hyperreactivity in the general population: the importance of atopy and airway calibre

The factors that determine the occurrence of airway hyperreactivity in the general population are not clearly understood. This study was designed to assess the independent effects of age, atopy, smoking and airway calibre. In a random sample of 2,415 adults aged 18-70 yrs we measured reactivity to methacholine as the dose provoking a 20% fall (PD20) in one-second forced expiratory volume (FEV1), atopy as the mean skin wheal response to three common environmental allergens, and airway calibre as the baseline FEV1 in absolute terms, as percent predicted (FEV1 % predicted) and as percent forced vital capacity (FEV1 % FVC). Hyperreactivity, defined as a PD20 < or = 12.25 mumol, was present in 314 (13%) of the sample, and before adjustment for FEV1 was more common in females (independent odds ratio (OR) = 2.05 (95% confidence interval 1.6-2.7)), current smokers (OR = 1.89 (1.3-2.6)), atopics (OR = 1.39 (1.3-1.5) per mm skin wheal), and in older age groups (OR for age 60-70 yrs relative to 18-29 yrs = 2.70 (1.7-4.3)). However, the odds of hyperreactivity were also strongly and independently related to absolute FEV1 (OR = 0.46 (0.27-0.77) per litre), FEV1 % predicted (OR = 0.96 (0.94-0.98) per percent), and FEV1 % FVC (OR = 0.92 (0.90-0.94) per percent; combined chi-square on 3 df = 312, p << 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS)

Identification of beet western yellows luteovirus genes implicated in viral replication and particle morphogenesis

The roles in replication and viral assembly of different beet western yellows luteovirus gene products were investigated in Chenopodium quinoa protoplasts using mutated transcripts. Of the six long open reading frames (ORFs) present on the viral RNA, only ORFs 2 and 3, which encode proteins containing conserved putative replicase domains, were essential for replication. Various deletions in the 3' part of the genome within ORFs 4, 5, and 6 did not affect viral replication. Analysis of the progeny of those mutants capable of replication showed that virus particles were produced in protoplasts infected with transcripts modified in ORFs 1, 5, or 6 but not with transcripts unable to produce coat protein, encoded by ORF 4.

Nucleotide sequence and genetic organization of peanut clump virus RNA 2 and partial characterization of deleted forms

The complete nucleotide sequence of peanut clump virus RNA 2 has been determined by characterization of cloned cDNA and by direct RNA sequencing. The sequence is 4503 residues in length and contains six long open reading frames (ORFs). The cistron for the coat protein (ORF 1) is located nearest the 5' end of the RNA and is separated from the 5' extremity by a noncoding region of 389 nucleotides. ORF 2 starts one nucleotide upstream of the first residue of the UGA termination codon of the coat protein cistron and encodes a polypeptide of 39300 M(r). Four additional ORFs with the potential to encode polypeptides with approximate M(r)'s of 51,000 (ORF 3), 13,800 (ORF 4), 9400 (ORF 5), and 6800 (ORF 6) are found on the 3' proximal half of the RNA. ORFs 3, 4, and 5 resemble the Triple Gene Block found in potexviruses, carlaviruses, a hordeivirus, and a furovirus. The 276 nucleotide 3' noncoding region of RNA 2 displays extensive sequence homology with the 3' noncoding region of RNA 1. Several peanut clump virus isolates propagated on Nicotiana benthamania contain RNA 2's significantly shorter than that of the type isolate. Partial characterization of two such isolates reveals that their RNA 2's have undergone deletions within ORF 2.

The secondary structure of the 5'-noncoding region of beet necrotic yellow vein virus RNA 3: evidence for a role in viral RNA replication

Secondary structure-sensitive chemical and enzymatic probes have been used to produce a model for the folding of the first 312 residues of the long 5'-noncoding region of beet necrotic yellow vein virus RNA 3. The structure consists of two major domains, one of which includes long distance base-pairing interactions between two short sequence elements (Box I and Box II) situated between positions 237 and 292 and complementary elements (Box I' and II') near the 5'-terminus. Previous studies have shown that base pairing between these sequence elements (in either the plus-strand or minus-strand RNA) is important for RNA 3 accumulation during infection. RNA 3 transcripts were produced containing mutations which preferentially disrupted Box II-II' base pairing in either the plus- or minus-strand. In infection experiments, transcripts with mutations which disrupted the Box II-II' interaction in the plus-strand structure replicated less efficiently than mutants in which the Box II-II' interaction was disrupted in the minus-strand. These findings indicate that the complex 5'-proximal plus-strand structure to which the Box II-II' interaction contributes comprises at least part of the promoter for plus-strand RNA synthesis.

Mapping the promoter for subgenomic RNA synthesis on beet necrotic yellow vein virus RNA 3

During infection of Tetragonia expansa leaves, RNA 3 of the quadripartite genome of beet necrotic yellow vein virus directs synthesis of a subgenomic RNA (RNA 3sub) which corresponds to the 3'-terminal 600 residues of the RNA 3 molecule. Biologically active run-off transcripts have been prepared from full-length cDNA of RNA 3 cloned behind a bacteriophage T7-RNA polymerase promoter. RNA 3 transcripts carrying deletions in the vicinity of the RNA 3sub initiation site were produced by site-directed mutagenesis at the cDNA level and then tested for their capacity to direct RNA 3sub synthesis in infected leaves. The cis-acting domain essential for normal levels of RNA 3sub production in planta (the 'core' promoter) did not extend in the 5'-direction beyond position -16 relative to the RNA 3sub transcription initiation site. The 3'-boundary of the core promoter domain was located somewhere between positions +100 and +208. Displacement of the promoter domain to an upstream site in RNA 3 produced a new subgenomic RNA starting at or near the predicted upstream site.

Agroinfection as an alternative to insects for infecting plants with beet western yellows luteovirus

Beet western yellows luteovirus, like other luteoviruses, cannot be transmitted to host plants by mechanical inoculation but requires an aphid vector, a feature that has heretofore presented a serious obstacle to the study of such viruses. In this paper we describe use of agroinfection to infect hosts with beet western yellows virus without recourse to aphids. Agroinfection is a procedure for introducing a plant virus into a host via Agrobacterium tumefaciens harboring a Ti plasmid, which can efficiently transfer a portion of the plasmid (T-DNA) to plant cells near a wound. The viral genome must be inserted into the T-DNA in such a way that it can escape and begin autonomous replication, a requirement that has, so far, limited agroinfection to pathogens with a circular genome. We have cloned cDNA corresponding to the complete beet western yellows virus RNA genome between the cauliflower mosaic virus 35S promoter and the nopaline synthase transcription termination signal. In one construct, a self-cleaving (ribozyme) sequence was included so as to produce a transcript in planta with a 3' extremity almost identical to natural viral RNA. When inoculated mechanically to host plants, the naked plasmid DNA was not infectious but, when introduced into T-DNA and agroinfected to plants, both the construct with and without the ribozyme produced an infection. This approach should be applicable to virtually any plant virus with a linear plus-strand RNA genome.

cis-active sequences near the 5'-termini of beet necrotic yellow vein virus RNAs 3 and 4

RNAs 3 and 4 of the multicomponent genome of beet necrotic yellow vein virus are dispensable for infection of Chenopodium quinoa leaves. We have used mutagenesis of biologically active RNA 3 transcripts to identify 5'-proximal sequences essential in cis for RNA 3 amplification. One such element, Box I, (nucleotides 283-292) was complementary to the first 10 residues (Box I') following the 5'-terminal cap. A second cis-active element (Box II) was identified between nucleotides 237-244 and was complementary to nucleotides 16-23 (Box II'). Other cis-active sequences exist between Box II' and II but have not been mapped to fine scale. Most sequence substitutions in Boxes I and II or in the 5'-proximal complementary sequences were lethal but compensatory mutations designed to restore Box I/I' or Box II/II' base pairing restored viability, suggesting that secondary structure involving these elements rather than their exact sequence is the critical feature. Transcripts bearing short deletions near residue 200 were replicated but did not assemble into virions, indicating that this region contains or contributes to a cis-active encapsidation signal. Similar experiments with RNA 4 transcript have shown that 5'-proximal cis-essential elements are limited to the first 400 residues of this RNA. Essential subdomains within this region have not been mapped but there are no structures obviously homologous to Boxes I/I' and II/II' of RNA 3.

Efficient cell-to-cell movement of beet necrotic yellow vein virus requires 3' proximal genes located on RNA 2

RNA 2 of beet necrotic yellow vein virus (BNYVV) carries six open reading frames. The four 3' proximal frames encode the proteins P42, P13, P15, and P14. The first three species present homologies to proteins encoded by three overlapping open reading frames (the triple gene block) in potexviruses, carlaviruses, and barley stripe mosaic virus. P14 does not display homology with other known plant viral proteins. The functions of P42, P13, P15, and P14 were investigated by site-directed mutagenesis. Full-length transcripts of wild-type BNYVV RNAs 1 and 2 were infectious when coinoculated to protoplasts or leaves of Chenopodium quinoa. RNA 2 transcripts in which P42, P13, and P15 were prematurely terminated by frameshift mutations replicated in protoplasts (when inoculated with wild-type RNA 1) but were not infectious to leaves, indicating that the triple gene block proteins of BNYVV are essential for viral cell-to-cell spread. Mutations in P14 were not lethal in leaf infections but smaller local lesions and lesser amounts of viral RNA were produced. RNA 2-related subgenomic RNA species of 2.6, 1.4, and 0.7 kb were detected; they presumably direct synthesis of P42, P13, and P14. No species of the length predicted for a P15-specific subgenomic RNA was detected.

Synthesis of full-length transcripts of beet western yellows virus RNA: messenger properties and biological activity in protoplasts

Full-length cDNA of beet western yellows virus genomic RNA has been cloned behind the bacteriophage T7 RNA polymerase promoter of the transcription vector BS(-). The in vitro run-off transcription product obtained in the presence of T7 RNA polymerase and m7GpppG cap has the same messenger properties as natural viral RNA in in vitro translation systems. The full-length transcript was also able to infect Chenopodium quinoa protoplasts inoculated by electroporation. Infection could be followed by the appearance of viral coat protein in the inoculated protoplasts and the de novo synthesis of viral RNA. Site-directed mutagenesis experiments revealed that expression of beet western yellows virus open reading frame 1 and the C-terminal portion of open reading frame 6 were not required for infection of protoplasts. Additional experiments with these mutants and mutants in the other viral open reading frames should provide information concerning the requirements for beet western yellows virus replication and, ultimately, the role of virus genes in other important steps in the virus infection cycle, such as aphid transmission.

Rapid antimicrobial susceptibility testing of gram-negative bacilli using Baxter MicroScan rapid fluorogenic panels and autoSCAN-W/A

The MicroScan Rapid Neg MIC/Combo panels and autoSCAN-W/A (Walk Away) system utilize automated fluorescence technology for rapid antimicrobial susceptibility testing of Gram-negative bacilli. In a three site clinical study eleven antimicrobial agents were evaluated by comparing results obtained with 741 clinical isolates, using rapid fluorogenic expanded dilution MIC panels and corresponding frozen microdilution reference panels determined visually. Results for 31%, 40%, 12% and 9% of the isolates were available within 3.5, 4.5, 5.5 and 7.0 hours respectively. Results for 7.3% were not available within that time period. For the seven drugs analyzed using a Minimum Inhibitory Concentration range of dilutions, overall agreement (+/- 1 dilution) was 94%, with 1.5% very major, 0.9% major and 2.5% minor errors. For the four drugs analyzed using a Breakpoint range of dilutions, overall agreement (+/- 1 dilution) was 97%, with two percent very major, and one percent major errors. The MicroScan Rapid Neg MIC system is an accurate and rapid method for same day determination of susceptibility of Gram-negative bacilli.

Shortened forms of beet necrotic yellow vein virus RNA-3 and -4: internal deletions and a subgenomic RNA

Beet necrotic yellow vein virus RNA-3 and RNA-4, produced as full-length biologically active transcripts in vitro, can undergo spontaneous internal deletions when inoculated onto Chenopodium quinoa leaves along with RNA-1 and -2. The deletion process is specific, giving rise to only a few major species, and can be rapid; deleted forms appear after only one or two passages in leaves. In one of the shortened forms of RNA-4, the deletion precisely eliminated one copy of a 15 nucleotide (nt) direct sequence repeat from the full-length prototype sequence, suggesting that 'copy-choice' switching of the replicase-template complex from one repeat to the other during RNA replication was responsible for the generation of this deletion. The deletion found in a major shortened form of RNA-3, on the other hand, did not occur near sequence repeats but began with GU and ended with AG like a nuclear intron sequence. Thus it is possible that the deleted sequence has been removed by splicing. However, two other deletions that were characterized were not associated with either of these types of sequence feature. An approximately 600 nt 5'-terminally truncated non-encapsidated form of RNA-3 was also detected in infected plant tissue. The evidence suggests that it is a subgenomic RNA derived from RNA-3.

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Multiplication of beet necrotic yellow vein virus RNA 3 lacking a 3' poly(A) tail is accompanied by reappearance of the poly(A) tail and a novel short U-rich tract preceding it

Beet necrotic yellow vein virus RNAs 1 and 2 but not RNAs 3 and 4 are required for viral multiplication in Chenopodium quinoa leaves. Elimination of the 3' poly(A) tail from RNA 3 transcripts markedly attenuated their ability to be amplified when co-inoculated with RNAs 1 and 2 to this host. Successful multiplication of the tailless RNA 3 was accompanied by the reappearance of new 3' poly(A) tails on the progeny. The evidence suggests that the newly acquired poly(A) sequence results from the action of a poly(A) polymerase rather than recombination with the homologous 3' terminal domains of RNAs 1 or 2. An unexpected feature of these progeny RNA 3 molecules was the presence of a novel short heterogenous U-rich tract separating the poly(A) tail from the 3' end of the heteropolymeric RNA 3 sequence proper.

Immunodetection in vivo of beet necrotic yellow vein virus-encoded proteins

Open reading frames identified on the four genomic RNAs of beet necrotic yellow vein virus were cloned into bacterial expression vectors and resulting cl-fusion proteins expressed in Escherichia coli were used to raise polyclonal antibodies. This set of antisera was used to show the presence of 7 of 9 predicted viral proteins in mechanically inoculated Chenopodium quinoa leaves by the Western blot technique. Viral coat protein (p22) and its readthrough protein p85 encoded by RNA-2 could be detected in all subcellular fractions. Two other RNA-2-encoded proteins, p42 and p13, are predominantly associated with membranous structures. Another RNA-2-encoded protein, p14, as well as the two polypeptides p25 and p31, encoded by RNA-3 and -4, respectively, are soluble proteins. The viral proteins could first be detected about the time lesions became visible and increased thereafter except for p85, in which case the amount of the soluble form decreased with time. No protein could be detected corresponding to the RNA-1-encoded p237 protein or to the p15 species encoded by open reading frame V of RNA-2.

Mapping sequences required for productive replication of beet necrotic yellow vein virus RNA 3

Of the four genome components of beet necrotic yellow vein virus only RNAs 1 and 2 are essential for viral replication in leaves. We have mapped cis-regulatory elements on RNA 3 by introducing deletions into expressible cDNA clones and inoculating leaves with the altered transcripts along with RNAs 1 and 2. Transcripts carrying internal deletions extending to within 69 residues of the 3' poly(A) tail or to within about 300 residues of the 5' terminus were efficiently amplified and encapsidated in vivo. The 3' terminal cis-essential domain can be folded into a secondary structure which is conserved among all four genomic RNAs and which probably contains the minus-strand promoter. RNA 3 transcripts with 75% of the central core of the sequence deleted or replaced by the beta-glucuronidase (GUS) gene were also viable. GUS activity was detected in infected tissue in the latter case.

The triceps-dividing approach to open reduction of complex distal humeral fractures in adolescents: a Cybex evaluation of triceps function and motion

Triceps function and elbow motion were evaluated in nine elbows after open reduction of complex distal humeral fractures through a triceps dividing approach. At 3-year 6-month follow-up, the patients had an average flexion/extension of 136 degrees to -6 degrees. Triceps peak torque decreased slightly, measured by Cybex testing with a 6% deficit at 60 degrees/s, 3% deficit at 120 degrees/s, and 3% deficit at 180 degrees/s. We recommend triceps division rather than olecranon osteotomy in children who require open reduction of complex distal humeral fractures.

In vitro synthesis of biologically active beet necrotic yellow vein virus RNA

Beet necrotic yellow vein virus (BNYVV) has a quadripartite plus-strand RNA genome in which the two smallest genome components, RNA 3 and 4, are not necessary for virus multiplication in leaves. Infectious transcripts of BNYVV RNA 3 and 4 have already been described (V. Ziegler-Graff, S. Bouzoubaa, I. Jupin, H. Guilley, G. Jonard, and K. Richards (1988) J. Gen. Virol. 69, 2347-2357). In this paper we describe synthesis of a full-length RNA-1 transcript by bacteriophage T7 RNA polymerase-directed run-off transcription of cloned viral cDNA. A recombinant plasmid containing a full-length cDNA insert of RNA 2 could not be maintained in Escherichia coli. Therefore full-length transcript of RNA 2 was produced by transcription of cDNA ligation products without amplification in bacteria. When inoculated together to leaves of Chenopodium quinoa or Tetragonia expansa the RNA 1 and 2 transcripts were infectious; they also supported multiplication of the BNYVV RNA 3 and 4 transcripts, providing a totally synthetic inoculum of the virus. In one recombinant clone of RNA 2 a point mutation causing an arginine to serine substitution at position 119 of the viral coat protein was discovered. The mutation was detected because the resulting coat protein had altered electrophoretic mobility. RNA 2 transcripts containing this mutation were infectious but viral RNA was not encapsidated. The mutation also interfered with long distance movement of the virus in spinach, presumably as a consequence of the packaging deficiency.

Nucleotide sequence of beet western yellows virus RNA

The nucleotide sequence of the genomic RNA (5641 nt) of beet western yellow virus (BWYV) isolated from lettuce has been determined and its genetic organization deduced. The sequence of the 3'terminal 2208 nt of RNA of a second BWYV isolate, obtained from sugarbeet, was also determined and was found to be very similar but not identical to that of the lettuce isolate. The complete sequence of BWYV RNA contains six long open reading frames (ORFs). A cluster of three of these ORFs, including the coat protein cistron, display extensive amino acid sequence homology with corresponding ORFs of a second luteovirus, the PAV isolate of barley yellow dwarf virus (BYDV) (1,2). The ORF corresponding to the putative viral RNA-dependant RNA polymerase, on the other hand, resembles that of southern bean mosaic virus. There is circumstantial evidence that expression of the BWYV RNA polymerase ORF may involve a translational frameshift mechanism. The ORF immediately following the coat protein cistron may be translated by in-frame readthrough of the coat protein cistron amber termination codon. Similar mechanisms have been proposed for expression of the corresponding ORFs of BYDV(PAV) (1).