mtDNA diversity in human populations highlights the merit of haplotype matching in gene therapies.

STUDY QUESTION: Does mitochondrial DNA (mtDNA) diversity in modern human populations potentially pose a challenge, via mtDNA segregation, to mitochondrial replacement therapies? SUMMARY ANSWER: The magnitude of mtDNA diversity in modern human populations is as high as in mammalian model systems where strong mtDNA segregation is observed; consideration of haplotype pairs and/or haplotype matching can help avoid these potentially deleterious effects. WHAT IS KNOWN ALREADY: In mammalian models, substantial proliferative differences are observed between different mtDNA haplotypes in cellular admixtures, with larger proliferative differences arising from more diverse haplotype pairings. If maternal mtDNA is 'carried over' in human gene therapies, these proliferative differences could lead to its amplification in the resulting offspring, potentially leading to manifestation of the disease that the therapy was designed to avoid-but existing studies have not investigated whether mtDNA diversity in modern human populations is sufficient to permit significant amplification. STUDY DESIGN, SIZE, DURATION: This theoretical study used over 7500 human mtDNA sequences from The National Center for Biotechnology Information (NCBI), a range of international and British mtDNA surveys, and 2011 census data. PARTICIPANTS/MATERIALS, SETTING, METHODS: A stochastic simulation approach was used to model random haplotype pairings from within different regions. In total, 1000 simulated pairings were analysed using the basic local alignment search tool (BLAST) for each region. Previous data from mouse models were used to estimate proliferative differences. MAIN RESULTS AND THE ROLE OF CHANCE: Even within the same haplogroup, differences of around 20-80 single-nucleotide polymorphisms (SNPs) are common between mtDNAs admixed in random pairings. These values are sufficient to lead to substantial segregation in mouse models over an organismal lifetime, even given low starting heteroplasmy, inducing increases from 5% to 35% over 1 year. Substantial population mixing in modern UK cities increases the expected genetic differences. Hence, the likely genetic differences between humans randomly sampled from a population may well allow substantial amplification of a disease-carrying mtDNA haplotype over the timescale of a human lifetime. We report ranges and mean differences for all statistics to quantify uncertainty in our results. LIMITATIONS/REASONS FOR CAUTION: The mapping from mouse and other mammalian models to the human system is challenging, as timescales and mechanisms may differ. Reporting biases in NCBI mtDNA data, if present, may affect the statistics we compute. We discuss the robustness of our findings in the light of these concerns. WIDER IMPLICATIONS OF THE FINDINGS: Matching the mtDNA haplotypes of the mother and third-party donor in mitochondrial replacement therapies is supported as a means of ameliorating the potentially deleterious results of human mtDNA diversity. We present a chart of expected SNP differences between mtDNA haplogroups, allowing the selection of optimal partners for therapies. LARGE SCALE DATA: N/A STUDY FUNDING/COMPETING INTERESTS: The authors report no external funding sources or conflicts of interest.

Self-assembly, modularity, and physical complexity.

We present a quantitative measure of physical complexity, based on the amount of information required to build a given physical structure through self-assembly. Our procedure can be adapted to any given geometry, and thus, to any given type of physical structure that can be divided into building blocks. We illustrate our approach using self-assembling polyominoes, and demonstrate the breadth of its potential applications by quantifying the physical complexity of molecules and protein complexes. This measure is particularly well suited for the detection of symmetry and modularity in the underlying structure, and allows for a quantitative definition of structural modularity. Furthermore we use our approach to show that symmetric and modular structures are favored in biological self-assembly, for example in protein complexes. Lastly, we also introduce the notions of joint, mutual and conditional complexity, which provide a useful quantitative measure of the difference between physical structures.

The pulmonary artery catheter in Australasia: a survey investigating intensive care physicians' knowledge and perception of future trends in use.

A survey was conducted to assess the knowledge and trends of use of the pulmonary artery catheter amongst intensive care practitioners in Australasia. A 31-item multiple choice questionnaire, identical to one previously trialled in studies in the United States and Europe, was distributed to all registered intensive care specialists and trainees working in intensive care units in Australasia. Five-hundred-and-forty-one questionnaires were distributed and 151 (27.9%) were returned, with an average mark of 82.7% +/- 9.3% and a range of 53.3 to 100%. Total score was significantly associated with years of experience in intensive care (P < 0.04), number of pulmonary artery catheters inserted (P < 0.015) and whether or not the respondent had passed the Joint Faculty of Intensive Care Medicine examination (P < 0.01). Scores were significantly higher amongst trainees (P < 0.0001) and physicians who had passed the Joint Faculty of Intensive Care Medicine examination (P < 0.0001). Overall, 44.9% of respondents indicated their use of the pulmonary artery catheter was decreasing, with 42.6% indicating their use was the same over the past five years. Sixty-one percent of respondents indicated they either agreed or strongly agreed with the statement that the use of echocardiography should supersede the use of the pulmonary artery catheter by intensive care specialists in the future. We concluded that in this study, knowledge of the pulmonary artery catheter and its use is better in Australasia than in previous studies in North America and Europe. The majority of respondents in Australasia believe that echocardiography will supersede the use of the pulmonary artery catheter in the future.

Survey of intensive care nurses' knowledge relating to the pulmonary artery catheter.

In 2003 there was an increase in the use of pulmonary artery catheters in Australia from 12,000 to 16,000 units in intensive care and peri-operative care. This survey of intensive care nurses in five intensive care units in Queensland addressed knowledge of use, safety and complications of the pulmonary artery catheter, using a previously validated 31 question multiple choice survey. One hundred and thirty-nine questionnaires were completed, a response rate of 46%. The mean score was 13.3, standard deviation +/-4.2 out of a total of 31 (42.8% correct). The range was 4 to 25. Scores were significantly higher in those participants with more ICU experience, higher nursing grade, a higher self-assessed level of knowledge and greater frequency of PAC supervision. There was no significant correlation between total score and hospital- or university-based education, or total score and public or private hospital participants. Fifty-one per cent were unable to correctly identify the significant pressure change as the catheter is advanced from the right ventricle to the pulmonary artery.

Which women want food during labour?: results of an audit in a Scottish DGH.

OBJECTIVE: To assess the proportion of women who would want to eat during labour and to identify any distinguishing characteristics of this group. DESIGN: Audit questionnaire, completed within 36 hours of delivery. SUBJECTS: One hundred and forty nine post-natal women, over a five-week period. RESULTS: A significant minority (30%) of women would wish to eat during labour. A quarter of these feel that eating would have significantly enhanced their satisfaction during the event. In addition, some of these women admitted to eating secretly during labour. CONCLUSIONS: Clinicians involved in the care of pregnant women should be aware of the arguments for and against allowing food during labour, in order to help these women reach an informed decision.

Molecular cloning of a novel mRNA using an antibody directed against synaptic glycoproteins.

It has been suggested by a number of investigators that glycoproteins may play a role in the development and/or maintenance of synapses in the mammalian CNS. For many synaptic glycoproteins, however, little precise structural or functional information is available. In an effort to isolate probes specific to individual glycoproteins, we have screened a rat brain cDNA expression library with a mixed polyclonal antibody directed against concanavalin A-binding synaptic junctional glycoproteins. Using this approach, we have previously reported the cloning of SC1, a putative extracellular matrix glycoprotein found in adult brain (Johnston et al., Neuron 2:165-176, 1990). We now report the cloning and characterization of a second novel cDNA, which has been designated SC2. Northern blots show that this cDNA recognizes a 1.2-kb mRNA that is present throughout postnatal development in the rat. It is expressed at high levels in brain and is also found at lower levels in several other tissues. In situ hybridization suggests that the SC2 mRNA is strongly expressed by many types of neurons. Sequence data reveals a single open reading frame in the cDNA, encoding a putative hydrophobic protein with a calculated molecular weight of 36.1 kDa. Sequence analysis reveals some similarity between SC2 and 5 alpha-reductase, a microsomal membrane protein important in testosterone metabolism.

Determination of contamination of a chemical warfare-proof operating theatre with volatile anaesthetic agents and assessment of anaesthetic gas scavenging systems.

Three types of anaesthetic waste scavenging systems (active antipollution system, Papworth Block passive system and activated charcoal absorber system) were compared with a non-scavenging control to assess their effectiveness in reducing waste halothane concentrations in a chemical warfare-proof operating theatre. All three systems were found to reduce the level of pollution significantly.

Flumazenil in ketamine and midazolam anaesthesia.

A double-blind, parallel group study using flumazenil and placebo was carried out to determine whether patients who received flumazenil would awake more quickly and whether this drug would reverse the protection conferred by midazolam on the psychic sequelae of ketamine. Fifty female patients were studied. The results showed that there was a significant reduction in awakening time (p = 0.02) and a very significant increase (p = 0.001) in the incidence of dreams in the flumazenil group.

Anaesthesia in the field. Spontaneous ventilation--a new technique.

In recent years the British Army has used the Triservice Anaesthetic Apparatus in the field. Trichloroethylene is no longer manufactured in the United Kingdom and halothane is not recommended for closely repeated anaesthetics. A method based on existing equipment is described for patients breathing spontaneously. A background infusion of ketamine, midazolam and alfentanil supplements the inhalation of isoflurane in oxygen-enriched air.

Molecular cloning of SC1: a putative brain extracellular matrix glycoprotein showing partial similarity to osteonectin/BM40/SPARC.

We describe the cloning of SC1, a novel cDNA that was selected from a rat brain expression library using a mixed polyclonal antibody directed against synaptic junction glycoproteins. SC1 detects a 3.2 kb mRNA expressed throughout postnatal development of the brain and present at high levels in the adult. In situ hybridization reveals that the SC1 mRNA is expressed widely in the brain and is present in many types of neurons. DNA sequence data suggest that the SC1 product is a secreted, calcium binding glycoprotein. Strikingly, the carboxy-terminal region of the SC1 protein shows substantial similarity to the extracellular matrix glycoprotein osteonectin/BM40/SPARC. These data are consistent with the hypothesis that SC1 is an extracellular matrix glycoprotein in the brain.