Tymovirus isolation and genomic RNA extraction.
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Genetic Techniques↗
Biomedical subjects
A Gibbs
Publications and source records attributed to A Gibbs.
Effect of Shear on the Strength of Polymer-Induced Flocs
Micromechanics was used to show that the rupture strength of polymer-induced flocs varied with the hydrodynamic conditions at which the flocs were formed. A maximum floc strength at an intermediate shear rate was observed. The overall performance of the polymeric flocculants, as determined by two independent methods, showed that the conditions for optimal flocculation did not coincide with those for maximum floc strength. The amount of flocculation was explained in terms of the competing effects of the particle collision frequency and the destructive hydrodynamic forces. The contributing forces to the floc strength are, however, more likely to be densification of the floc by shear and the weakening of reattachment strengths. The evidence presented here may be useful for explaining flocculation data that depart from the constant yield stress theory. Thus, the notion of the floc strength varying with shear rate may offer an alternative to multilevel floc structure models in the description of flocculation kinetics. Copyright 1997 Academic Press. Copyright 1997Academic Press
Journal Article↗
A primer pair for amplifying part of the genome of all potyvirids by RT-PCR.
Sequence analysis was used to design a pair of degenerate oligonucleotide primers that amplified a 1.6-2.1 kbp fragment from the 3' end of the genome (virion protein gene and part of the NIb gene) of 17 species of the Potyviridae ('potyvirids'); 11 potyviruses, 2 bymoviruses, 2 macluraviruses, an ipomovirus and a rymovirus. The 'potyvirid primer 1' hybridizes to the 3' terminal poly-A region of the genome, and 'potyvirid primer 2' to the genomic region encoding the-GNNSGQ-motif of the NIb protein. Database searches showed that the potyvirid 2 primer is specific for potyvirids. Associated analyses indicated that the published amino acid sequence of part of the wheat streak mosaic rymovirus NIb protein is probably incorrect in part.
Amino Acid Sequence↗
Completeness of reporting on prognostic factors for breast cancer: a regional survey.
BACKGROUND: Effective management of breast cancer is dependent on adequate pathological reporting of the surgical specimen. OBJECTIVE: To describe the frequency with which histopathological features of known prognostic importance are routinely recorded. STUDY POPULATION: 885 cases of invasive breast cancer diagnosed in NHS laboratories in Lancashire and Greater Manchester. METHODS: Pathology reports were reviewed for details for tumour histological type, size, and grade, the presence or absence of tumour in blood or lymphatic vascular channels, and a comment on the proximity of tumour to the lines of surgical excision. Laboratories were categorised according to their throughput of cases of breast cancer, involvement in the breast screening programme, and whether they were attached to a teaching hospital. RESULTS: Histological type, tumour size, presence or absence of tumour in vascular channels, and adequacy of excision were recorded for 843 (95%), 803 (91%), 436 (49%), and 761 (86%) cases, respectively. Non-screening and low throughput laboratories were significantly less likely to record certain histopathological features. No significant differences were observed between teaching and non-teaching hospitals. CONCLUSIONS: The substantial interlaboratory variation in the histopathological reporting of breast cancers can, in part, be related to throughput of cases and involvement in the breast screening programme.
Adult↗
Does additional lubrication reduce condom failure?
It has been suggested that using additional spermicide with condoms provides added contraceptive effect and protection from infection, and that water-based lubricants may lower condom breakage rates. This questionnaire-based study investigated the use of additional lubrication with condoms amongst 525 female students presenting for post-coital contraception, and the current and past experience of condom and additional lubrication use amongst 481 controls attending the same health centre. Of those requesting post-coital contraception, 83% claimed condom failure as the cause, with 66% of the control group having also experienced condom failure at some time. Use of additional water-based lubrication was significantly associated with lower condom failure rates (odds ratio 8.88, 95% C.I.: 3.79, 20.8). Gender, regularity of use of condoms and using oil-based lubricants were not associated with higher failure rates. Additional lubricant use was not significantly associated with increased condom slippage.
Condoms↗
Sex- and age-related changes in the biophysical properties of cuticular lipids of the housefly, Musca domestica.
We examined the biophysical properties of cuticular lipids isolated from the housefly, Musca domestica. Melting temperatures (Tm) of surface lipids isolated from female houseflies decreased from 39.3 degrees C to 35.3 degrees C as the females attained sexual maturity and produced sex pheromone, whereas those prepared from males did not change with age. Lipids melted over a 10-25 degrees C temperature range, and their physical properties were a complex function of the properties of the component lipids. The Tm of total cuticular lipids was slightly below that of cuticular hydrocarbons (HC), the predominant lipid fraction. Hydrocarbons were further fractionated into saturated, unsaturated, and methyl-branched components. The order of decreasing Tm was total alkanes > total HCs > methyl-branched alkanes > alkenes. For 1-day-old flies, measured TmS of hydrocarbons were 1.3-5.5 degrees C lower than TmS calculated from a weighted average of TmS for saturated and unsaturated components. For 4-day-old flies, calculated TmS underestimated Tm by 11-14 degrees C.
Aging↗
DIPLOMO: the tool for a new type of evolutionary analysis.
A package of computer programs called DIPLOMO (DIstance PLOt MOnitor) has been developed for making pairwise comparisons of different estimates of the distances between a set of taxa by plotting them against each other in a simple scatter plot. Taxa with similar relative distance characteristics are thereby grouped graphically. Groupings of different taxa may be directly identified, and the distance characteristics of chosen groups visualised and compared using devices to give them different colours or symbols. The program is particularly useful for detecting and analysing subtle trends in gene sequence evolution. This is done by comparing different components of change, for example synonymous versus non-synonymous nucleotide changes, transversions versus transitions and changes in different genes of the same set of taxa, etc. The program has a wide range of other uses, for example comparing different methods of sequence analysis, assessing which components of genetic change correlate best with phenotypic change or with geographical separation. This paper describes the DIPLOMO package, and illustrates typical DIPLOMO analyses using lentivirus gene sequence data.
Biological Evolution↗
Replication slippage in the evolution of potyviruses.
Recently published evidence for sequence repetition in potyvirus genomes prompted us to analyse the published complete genome sequences and coat protein gene sequences of viruses of this family for evidence of replication slippage. Five of nine complete genomic sequences and 17 of 32 coat protein genes had significant sequence repetitions. Most of these were in coat protein genes, although the 5' region of the turnip mosaic virus genome also showed evidence of slippage. The results suggest that replication slippage may be involved in the evolution of viruses, as well as prokaryotes and eukaryotes, and that slippage can occur in both RNA and DNA when it is being replicated.
Biological Evolution↗
Spontaneous ovulatory cycle donor insemination programme: prognostic indicators of a successful pregnancy.
The effects of female and male infertility factors as well as the insemination regime on the outcome of donor insemination (DI) during 1001 spontaneous ovulatory cycles were assessed. Overall, the average monthly fecundability was 4.4% and the cumulative conception rate after nine cycles was 45%. Female DI recipients' age, nulligravidity or the presence of other infertility factors were associated with a significantly lower pregnancy rate. DI recipients of azoospermic partners had a significantly higher pregnancy rate. The likelihood of a successful pregnancy was higher when more frequent (> or = 1) inseminations were used or in association with higher cervical score and larger follicle diameter at the time of insemination. We suggest that female recipients of DI should be fully investigated before commencing DI treatment. Early resort to other methods of assisted reproduction should be considered in DI recipients aged > or = 35 years, or in younger women if they fail to conceive after nine cycles of DI. More frequent and better timing of inseminations is expected to improve the fecundability rate during spontaneous ovulatory DI cycles.
Adult↗
Plant viruses: master explorers of evolutionary space.
Viruses represent the epitome of genetic diversity, encompassing both DNA and RNA genomes. Their variability probably results from high mutation rates, extensive genetic recombination, gene duplication, large populations and ancient origins. In addition, at least a third of all viral genes may have de novo origins. There is also recent evidence that additional novelty may be generated by genetic recombination between viruses and their plant hosts. Viruses are indeed master explorers of evolutionary space.
Biological Evolution↗
Pulmonary veno-occlusive disease and Hodgkin's lymphoma.
Pulmonary veno-occlusive disease (PVOD) is a rare cause of pulmonary hypertension, and is of unknown aetiology. It has seldom been described in association with malignant disease and cytotoxic chemotherapy, and there have been only two previous reports of an association with Hodgkin's disease [1, 2]. We report a third case which developed 14 yrs after Hodgkin's disease had been diagnosed and treated, initially with radiotherapy and subsequently with chemotherapy.
Adult↗
Origins of genes: "big bang" or continuous creation?
Many protein families are common to all cellular organisms, indicating that many genes have ancient origins. Genetic variation is mostly attributed to processes such as mutation, duplication, and rearrangement of ancient modules. Thus it is widely assumed that much of present-day genetic diversity can be traced by common ancestry to a molecular "big bang." A rarely considered alternative is that proteins may arise continuously de novo. One mechanism of generating different coding sequences is by "overprinting," in which an existing nucleotide sequence is translated de novo in a different reading frame or from noncoding open reading frames. The clearest evidence for overprinting is provided when the original gene function is retained, as in overlapping genes. Analysis of their phylogenies indicates which are the original genes and which are their informationally novel partners. We report here the phylogenetic relationships of overlapping coding sequences from steroid-related receptor genes and from tymovirus, luteovirus, and lentivirus genomes. For each pair of overlapping coding sequences, one is confined to a single lineage, whereas the other is more widespread. This suggests that the phylogenetically restricted coding sequence arose only in the progenitor of that lineage by translating an out-of-frame sequence to yield the new polypeptide. The production of novel exons by alternative splicing in thyroid receptor and lentivirus genes suggests that introns can be a valuable evolutionary source for overprinting. New genes and their products may drive major evolutionary changes.
Biological Evolution↗
Familial mesothelioma. Details of 17 cases with histopathologic findings and mineral analysis.
Nine new cases of mesothelioma clustering in four families are described, and additional information is provided on four previously reported families. All of the members of these families had some exposure to asbestos. Diagnoses were confirmed histologically, and the relevance of the histologic pattern is discussed after the literature review. The lung mineral fiber burden was quantified in patients by transmission electron microscopic examination and energy-dispersive x-ray analysis, and this confirmed significant exposure to amphibole asbestos in all patients. Evidence supporting an increased incidence of mesothelioma in family members is discussed.
Aged↗
Comparisons of the genomic sequences of erysimum latent virus and other tymoviruses: a search for the molecular basis of their host specificities.
The nucleotide sequence of the genome of erysimum latent tymovirus (ELV) has been determined. It closely resembles those of the other four sequenced tymoviral genomes in its gene organization and composition, but is the smallest (6034 nucleotides) and most distinct of them. Furthermore the 78 non-coding nucleotides at the 3' terminus of the ELV genome are unable to form a complete tRNA-like structure like that reported for other tymoviruses. Comparisons of the five tymovirus genomes and their encoded proteins indicate that they have probably evolved from the progenitor tymovirus by independent progressive mutational change without genetic recombination. Comparisons of the sequences of the two non-virion proteins of five tymoviruses, and virion proteins of 17 tymoviruses, revealed no specific similarities between those of ELV and turnip yellow mosaic virus that could explain why their host ranges and symptoms are so similar, yet differ, in this respect, from ononis yellow mosaic, kennedya yellow mosaic and eggplant mosaic tymoviruses.
Amino Acid Sequence↗
Bacterial toxins: a possible cause of cot death.
AIM: To test the hypothesis that sudden infant death syndrome (SIDS) may be caused by toxins of commonly occurring bacteria in infants lacking developed immunity. METHODS: Nasopharyngeal microbial isolates from 22 pairs of SIDS cases and healthy infants matched for age (by month), sex, and sampling time (by month) were compared for lethal toxigenicity. Crude toxin preparations were made from isolates cultured on dialysis membrane overlaid on agar, and these preparations were then tested for lethality by intravenous injection into 11 day old chick embryos. RESULTS: Fifteen (68%) of the SIDS cases were each found to have at least one lethally toxigenic organism in their nasopharyngeal flora; only eight (36%) of the flora of normal infants included a lethally toxigenic species. CONCLUSION: Infants who have died of SIDS have a significantly higher (p less than 0.05) probability than matched healthy infants of having a lethally toxigenic bacterial species in their nasopharyngeal flora.
Bacteria↗
Lethal synergistic action of toxins of bacteria isolated from sudden infant death syndrome.
AIM: To test the hypothesis that lethal toxins of bacteria associated with sudden infant death syndrome (SIDS) can act synergistically. METHODS: Bacteria occurring together in the nasopharynx of cases of cot death were studied. The lethal toxicity of crude toxin preparations was determined over a range of dilutions by injections into the chorioallantoic vein of the chick embryo. Toxin preparations of low lethality for the chick embryo SIDS model were then tested in combination. RESULTS: Staphylococcus aureus toxin preparations showed low lethality when tested alone, even at low dilution. At 1 in 100 dilution S aureus toxin was lethal to one out of 15 chick embryos. Escherichia coli toxin preparations showed high lethality except on high dilution (1 in 80) when lethality fell to two out of 15 of chick embryos. When the same toxin preparations were tested simultaneously in combination, lethality rose to 14 out of 15. Similar findings were observed over a range of toxin dilutions. This finding was highly significant (p = 0.0012). CONCLUSIONS: That synergy between toxins can enhance the lethality of toxins elaborated by bacteria associated with SIDS.
Animals↗
Optimal conditions for the analysis of Pasteurella haemolytica lipopolysaccharide by sodium dodecyl sulphate-polyacrylamide gel electrophoresis.
The optimal conditions for the analysis of the lipopolysaccharide (LPS) of two serotype A1 isolates and a serotype A2 isolate of Pasteurella haemolytica by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and silver staining were determined. The LPS of the A1 isolates possessed O side chains, consisting of high molecular mass bands with the appearance of a ladder-like pattern, as well as a low molecular mass core-oligosaccharide region; the LPS of the A2 isolate consisted only of the core-oligosaccharide region. Furthermore, the LPS of the two A1 isolates differed in the core-oligosaccharide region. Optimal resolution of low molecular mass LPS components was obtained in a 15% acrylamide resolving gel containing 4 M urea whereas optimal resolution of high molecular mass components was obtained when urea was omitted. Conventional silver staining resulted in excellent visualisation of LPS bands, whereas a modified staining method did not detect additional bands, as has been demonstrated with the LPS of Pseudomonas aeruginosa. Proteinase K digestion of outer membranes gave more clearly defined LPS profiles than did similar digestions of whole cells, and more closely resembled the profiles of purified LPS. With the exception of slight variation in the average molecular mass of a group of O side chains between logarithmic and stationary phases there were no differences in LPS profiles at various stages of the growth cycle; freezing and thawing of LPS samples had no effect on the profiles.
Animals↗
Genetic and acclimatory variation in biophysical properties of insect cuticle lipids.
Epicuticular lipids provide the primary barrier to water loss in insects and other terrestrial arthropods. Using Fourier transform infrared spectroscopy, we found that the melting temperatures for these lipids in the grasshopper Melanoplus sanguinipes varied by over 10 degrees C between individuals. The most significant determinant of lipid melting temperature was geographic population, followed by family effects and rearing regime. The width of the phase transition also showed population and family effects. Differences in lipid phase properties were correlated with habitat temperature. Our results provide evidence for genetically based intraspecific variation in epicuticular lipids and have important implications for physiological studies of water balance in arthropods.
Journal Article↗