Biosurfactants Produced by Phyllosphere-Colonizing Pseudomonads Impact Diesel Degradation but Not Colonization of Leaves of Gnotobiotic Arabidopsis thaliana.

Biosurfactant production is a common trait in leaf surface-colonizing bacteria that has been associated with increased survival and movement on leaves. At the same time, the ability to degrade aliphatics is common in biosurfactant-producing leaf colonizers. Pseudomonads are common leaf colonizers and have been recognized for their ability to produce biosurfactants and degrade aliphatic compounds. In this study, we investigated the role of biosurfactants in four non-plant-pathogenic Pseudomonas strains by performing a series of experiments to characterize their surfactant properties and their role during leaf colonization and diesel degradation. The biosurfactants produced were identified using mass spectrometry. Two strains produced viscosin-like biosurfactants, and the other two produced massetolide A-like biosurfactants, which aligned with the phylogenetic relatedness between the strains. To further investigate the role of surfactant production, random Tn5 transposon mutagenesis was performed to generate knockout mutants. The knockout mutants were compared to their respective wild types with regard to their ability to colonize gnotobiotic Arabidopsis thaliana and to degrade diesel or dodecane. It was not possible to detect negative effects during plant colonization in direct competition or individual colonization experiments. When grown on diesel, knockout mutants grew significantly slower than their respective wild types. When grown on dodecane, knockout mutants were less impacted than during growth on diesel. By adding isolated wild-type biosurfactants, it was possible to complement the growth of the knockout mutants.IMPORTANCE Many leaf-colonizing bacteria produce surfactants and are able to degrade aliphatic compounds; however, whether surfactant production provides a competitive advantage during leaf colonization is unclear. Furthermore, it is unclear if leaf colonizers take advantage of the aliphatic compounds that constitute the leaf cuticle and cuticular waxes. Here, we tested the effect of surfactant production on leaf colonization, and we demonstrate that the lack of surfactant production decreases the ability to degrade aliphatic compounds. This indicates that leaf surface-dwelling, surfactant-producing bacteria contribute to degradation of environmental hydrocarbons and may be able to utilize leaf surface waxes. This has implications for plant-microbe interactions and future studies.

Identification of genes deregulated during serum-free medium adaptation of a Burkitt's lymphoma cell line.

OBJECTIVE: Serum is usually added to growth media when mammalian cells are cultured in vitro to supply the cells with growth factors, hormones, nutrients and trace elements. Defined proteins and metal ions, such as insulin, growth factors, transferrin and sodium selenite, are sometimes also included and can in some cases substitute serum components. How adaptation to serum free media influences cells has not been studied in detail. MATERIALS AND METHODS: We have adapted the Burkitt's lymphoma line Ramos to a serum-free medium that supports long-term survival and studied gene expression changes that occurred during the adaptation process. RESULTS AND CONCLUSIONS: The adaptation process was characterized by initial cell population growth arrest, and after that extensive cell death, followed by proliferation and long-term survival of clonal cultures. Proliferation and cell cycle progression of the serum-free cultures closely mimicked that of serum-dependent cells. Affymetrix micro-array technology was used to identify gene expression alterations that had occurred during the adaptation. Most changes were subtle, but frequently the genes with altered expression were involved in basal cellular functions such as cell division, cell cycle regulation, apoptosis and cell signalling. Some alterations were restored when the cells were transferred back to serum-containing medium, indicating that expression of these genes was controlled by components in serum. Others were not, and may represent changes that were selected during the adaptation process. Among these were, for example, several genes within the Wnt signalling pathway.

Competitive formation of helical cycloocta- and cyclododecapyrroles.

In connection with a study aimed at the evaluation of electronic effects in spiro-dicorrole (1a) and its binuclear Ni(II) complex (1b) we became interested in gem-dimethyl-substituted cyclotetrapyrrole (2a) and the corresponding Ni(II) complex (2b). Attempts to prepare 2a as the 12,13,16,17-tetraethyl-2,3,7, 8-tetramethyl derivative (5) by an acid-catalyzed (1 + 1) condensation of dimethyldipyrrylmethane 3 and diformylbipyrrole 4 resulted in the formation of the (2 + 2) and (3 + 3) condensation products, i.e., the cyclooctapyrrole 6 and the cyclododecapyrrole 7, respectively, rather than in that of the desired gem-dimethyl cyclotetrapyrrole. The cyclododecapyrrole 7, isolated as the major product, is among the largest cyclopolypyrroles known to date. These two new macrocycles have been structurally characterized by variable temperature 1D and 2D NMR experiments, as well as by single-crystal X-ray diffraction analysis. In solution both the cyclooctapyrrole 6 and cyclododecapyrrole 7 exhibit dynamic behavior. At 337 K 6 adopts a D(2)-symmetric conformation, whereas at 196 K two equivalent C(2) conformers that interconvert through the D(2)-symmetric intermediate are observed. The energy barrier for the interconversion process between these two degenerate conformers is found to be 10.6 kcal mol(-)(1). The solution dynamics of 7 could be described in an analogous manner, with the time-averaged conformation at 378 K displaying D(3)(h)() symmetry. X-ray analyses showed that for both macrocycles, 6 and 7, the solid state structures were nearly identical to the low-temperature solution conformers.

"Figure Eight" Cyclooctapyrroles: Enantiomeric Separation and Determination of the Absolute Configuration of a Binuclear Metal Complex.

The hypothesized racemate separation of cyclooctapyrroles with chiral figure eight conformations-and of metal complexes derived from these ligands-has been realized. The cyclooctapyrrole 1 (as hexadecaethyl derivative), which according to NMR analysis exhibits restricted mobility, and its binuclear palladium and copper complexes could be separated into stable enantiomers by preparative chromatography on a chiral phase. In the case of the palladium complex and the free ligand 1 it was also possible to determine the absolute configuration of the enantiomers.

A randomized controlled trial of exercise therapy for dizziness and vertigo in primary care.

BACKGROUND: 'Vestibular rehabilitation' (VR) is an increasingly popular treatment option for patients with persistent dizziness. Previous clinical trials have only evaluated the effects of specialist therapy programmes in small, selective, or uncontrolled patient samples. AIM: To determine the benefits of VR compared with standard medical care, using a brief intervention for dizzy patients in primary care. METHOD: Adults consulting their general practitioner (GP) with dizziness or vertigo were randomly assigned to treatment or control groups. Patients in both groups received the same evaluation at baseline, six-week follow-up, and six-month follow-up, comprising examination of nystagmus, postural control, and movement-provoked dizziness, and a questionnaire assessment of subjective status, symptoms, handicap, anxiety, and depression. At baseline and six weeks later, the treatment group also received an individualized 30-minute therapy session, in which they were taught head, eye, and body exercises designed to promote vestibular compensation and enhance skill and confidence in balance. RESULTS: The treatment group (n = 67) improved on all measures, whereas the control group (n = 76) showed no improvement, resulting in a significant difference between the two groups on physical indices of balance and subjective indices of symptoms and distress. Odds ratios for improvement in treated patients relative to untreated patients were 3.1:1 at six weeks (95% CI = 1.4-6.8) and 3.8:1 at six months (95% CI = 1.6-8.7). CONCLUSION: VR is a simple, inexpensive, and beneficial treatment, and may be an appropriate first stage of management for many dizzy patients in primary care.

Voluntary, named testing for HIV in a community based antenatal clinic: a pilot study.

Despite the increasing advantages of identifying HIV infection in pregnant women, only some 12% of HIV positive women attending antenatal clinics in London have been identified by named testing. As virtually all antenatal care will be community based within the next two to three years, we assessed the problems of introducing named HIV testing during pregnancy into the primary care setting. Planning the service took a considerable time and required the production of educational material for both staff and pregnant women and some reorganisation of procedures. Over a one year period an uptake of 44% was noted. Several problems were encountered including an average of 21 minutes needed to give information on AIDS and HIV, an adverse effect on the midwife-mother relationship, and anxiety (affecting both women and midwives). Possible solutions to this difficult problem are discussed.

Is HIV testing in antenatal clinics worthwhile? Can we afford it?

Since 0.2-0.4% of pregnant women attending antenatal clinics (ANC) at St Thomas's Hospital are HIV positive, and as the Department of Health (DH) have recommended that universal voluntary HIV testing be made available to women attending ANC in areas of "known or suspected higher prevalence of HIV infection", we examined the implications of the DH initiative in an Inner London Teaching Hospital as well as in a General Practice involved in shared care. The cost of the programme (148,300 pounds to 193,900 pounds), 80% of which relates to the need to obtain informed consent, was approximately 2.7-3.5 times that calculated by the DH. The DH based much of their costing on additional time for counselling rather than calculating the additional staff required. We estimated that 25% of women will require specialized counselling since 17% are of African ethnicity and others are injecting drug users or 'worried well'. Various means of reducing costs were considered but, until such time as explicit, informed consent is no longer considered necessary, the above resources will be required. Unless the DH continues to provide central direction to Providing Agencies to give priority to these recommendations and, where necessary, provides additional funding, we fear that this important public health initiative will be unsuccessful.

Consultants' and patients' views about patient access to their general practice records.

Semi-structured interviews were conducted with 24 hospital consultants and 47 general practice patients, asking for their opinions about a proposed policy of partial access to records in one general practice. Eleven consultants were opposed to the policy, 10 were in favour and three were classified as ambivalent. Arguments against access were couched largely in terms of consultants' own interests whereas arguments in favour of access were couched in terms of patients' interests. Although 81% of patients interviewed said that they should in principle be allowed to see their own records, only 51% wanted access to their own records. Fears expressed by consultants on patients' behalf are not necessarily well founded.

The St. Thomas's Hospital maternity case notes study: a randomised controlled trial to assess the effects of giving expectant mothers their own maternity case notes.

At an antenatal clinic in St. Thomas's Hospital, London, 246 expectant mothers were randomly allocated to hold either their own maternity case notes or the standard co-operation card. Information was collected on three occasions during their care on attitudes and health behaviour. Clinical outcomes were recorded and the effects of the two systems on clinic administration were observed. More of the notes group expressed satisfaction with most aspects of their care and delivery and significantly more of the notes group felt well informed and satisfied with their companion during labour. There were no differences in clinical outcomes between the two groups except that, for no identifiable systematic reason, there were more assisted deliveries among the notes group. A number of administrative advantages resulted from mothers holding their own notes and although initial reservations were found amongst professional staff interviewed at the start of the study, the results proved persuasive and the practice of giving mothers their own notes is now to be extended throughout the department.

Evaluation of a computer assisted repeat prescribing programme in a general practice.

After introducing a computer assisted repeat prescribing programme into a south London practice improvements were made in several aspects of practice organisation. Time was saved by doctors and receptionists; prescriptions were produced more rapidly; information in the records about drugs that were available for repeat prescription was improved; and queries from chemists about prescriptions were reduced. The costs of the system in terms of computer operator time were estimated. Computerising prescribing data provides a source of data that may be used to enable doctors to audit their own prescribing.