Drought-tolerant Pseudomonas sp. showed differential expression of stress-responsive genes and induced drought tolerance in Arabidopsis thaliana

The growth and persistence of rhizobacteria in soils are highly impacted by moisture stress. In this study, we report the first transcript analysis of four Pseudomonas strains (PS1, PS2, PS3, and PS4) isolated from the root-soil interface of rice and maize associated with different moisture levels during water deprivation. Filtered Pseudomonas sp. cells incubated at low (RH10%) and high (RH85%) relative humidity showed decreased survival of all Pseudomonas sp. at RH10% when compared with RH85%. RT-PCR showed differential expression of treS (trehalose synthase), rpoS (sigma factor), mucA (alginate regulatory gene), and fliM (flagellar motor switch protein gene) in response to exposure to RH10%. However, molecular fingerprinting and nutrient assimilation profile of Pseudomonas strains demonstrated genetic and physiological variation between the four strains irrespective of water regime and host. In vitro testing of these strains showed ACC deaminase activity and gibberellic acid, abscisic acid, indole acetic acid, and exopolysaccharide production. We determined that 50 μl of 1.2 × 10³  CFU ml^-1 of these Pseudomonas strains was enough to protect Arabidopsis plants against drought stress in a pot experiment. Inoculated plants increased their root colonization ability and biomass; however, PS2 showed higher survival (95%), relative water content (59%), chlorophyll (30%), glycine betaine (38%), proline (23%), and reduced MDA (43%) in shoots than irrigated control under induced water deprivation. It can be concluded that all Pseudomonas strains were effective in mitigating drought stress, however, PS2 appears to impart more resistance to drought than the other strains by upregulating key defense mechanisms.

Real-time forecasting of pesticide concentrations in soil

Forecasting pesticide residues in soils in real time is essential for agronomic purposes, to manage phytotoxic effects, and in catchments to manage surface and ground water quality. This has not been possible in the past due to both modelling and measurement constraints. Here, the analytical transient probability distribution (pdf) of pesticide concentrations is derived. The pdf results from the random ways in which rain events occur after pesticide application. First-order degradation kinetics and linear equilibrium sorption are assumed. The analytical pdfs allow understanding of the relative contributions that climate (mean storm depth and mean rainfall event frequency) and chemical (sorption and degradation) properties have on the variability of soil concentrations into the future. We demonstrated the two uncertain reaction parameters can be constrained using Bayesian methods. An approach to a Bayesian informed forecast is then presented. With the use of new rapid tests capable of providing quantitative measurements of soil concentrations in the field, real-time forecasting of future pesticide concentrations now looks possible for the first time. Such an approach offers new means to manage crops, soils and water quality, and may be extended to other classes of pesticides for ecological risk assessment purposes.

A Simple Method to Estimate Entropy and Free Energy of Atmospheric Gases from Their Action

A convenient practical model for accurately estimating the total entropy (ΣS_i) of atmospheric gases based on physical action is proposed. This realistic approach is fully consistent with statistical mechanics, but reinterprets its partition functions as measures of translational, rotational, and vibrational action or quantum states, to estimate the entropy. With all kinds of molecular action expressed as logarithmic functions, the total heat required for warming a chemical system from 0 K (ΣS_iT) to a given temperature and pressure can be computed, yielding results identical with published experimental third law values of entropy. All thermodynamic properties of gases including entropy, enthalpy, Gibbs energy, and Helmholtz energy are directly estimated using simple algorithms based on simple molecular and physical properties, without resource to tables of standard values; both free energies are measures of quantum field states and of minimal statistical degeneracy, decreasing with temperature and declining density. We propose that this more realistic approach has heuristic value for thermodynamic computation of atmospheric profiles, based on steady state heat flows equilibrating with gravity. Potentially, this application of an action principle can provide better understanding of emergent properties of many natural or evolving complex systems, including modelling of predictions for global warming.

A service evaluation of self-referral to military mental health teams

BACKGROUND

The UK military runs a comprehensive mental health service ordinarily accessed via primary care referrals.

AIMS

To evaluate the feasibility of self-referral to mental health services within a military environment.

METHODS

Three pilot sites were identified; one from each service (Royal Navy, Army, Air Force). Socio-demographic information included age, rank, service and career duration. Clinical data included prior contact with general practitioner (GP), provisional diagnosis and assessment outcome.

RESULTS

Of the 57 self-referrals, 69% (n = 39) had not previously accessed primary care for their current difficulties. After their mental health assessment, 47 (82%) were found to have a formal mental health problem and 41 (72%) were offered a further mental health clinician appointment. The data compared favourably with a large military mental health department that reported 87% of primary care referrals had a formal mental health condition.

CONCLUSIONS

The majority of self-referrals had formal mental health conditions for which they had not previously sought help from primary care; most were offered further clinical input. This supports the view that self-referral may be a useful option to encourage military personnel to seek professional care over and above the usual route of accessing care through their GP.

Randomized controlled trial comparing impact on platelet reactivity of twice-daily with once-daily aspirin in people with Type 2 diabetes

AIMS

Reduced aspirin efficacy has been demonstrated in people with Type 2 diabetes. Because increased platelet reactivity and/or turnover are postulated mechanisms, we examined whether higher and/or more frequent aspirin dosing might reduce platelet reactivity more effectively.

METHODS

Participants with Type 2 diabetes (n = 24) but without known cardiovascular disease were randomized in a three-way crossover design to 2-week treatment periods with aspirin 100 mg once daily, 200 mg once daily or 100 mg twice daily. The primary outcome was platelet reactivity, assessed using the VerifyNow(™) ASA method. Relationships between platelet reactivity and aspirin dosing were examined using generalized linear mixed models with random subject effects.

RESULTS

Platelet reactivity decreased from baseline with all doses of aspirin. Modelled platelet reactivity was more effectively reduced with aspirin 100 mg twice daily vs. 100 mg once daily, but not vs. 200 mg once daily. Aspirin 200 mg once daily did not differ from 100 mg once daily. Aspirin 100 mg twice daily was also more effective than once daily as measured by collagen/epinephrine-stimulated platelet aggregation and urinary thromboxane levels, with a similar trend measured by serum thromboxane levels. No episodes of bleeding occurred.

CONCLUSIONS

In Type 2 diabetes, aspirin 100 mg twice daily reduced platelet reactivity more effectively than 100 mg once daily, and numerically more than 200 mg once daily. Clinical outcome trials evaluating primary cardiovascular disease prevention with aspirin in Type 2 diabetes may need to consider using a more frequent dosing schedule.

Does language dominance affect cognitive performance in bilinguals? Lifespan evidence from preschoolers through older adults on card sorting, Simon, and metalinguistic tasks

This study explores the extent to which a bilingual advantage can be observed for three tasks in an established population of fully fluent bilinguals from childhood through adulthood. Welsh-English simultaneous and early sequential bilinguals, as well as English monolinguals, aged 3 years through older adults, were tested on three sets of cognitive and executive function tasks. Bilinguals were Welsh-dominant, balanced, or English-dominant, with only Welsh, Welsh and English, or only English at home. Card sorting, Simon, and a metalinguistic judgment task (650, 557, and 354 participants, respectively) reveal little support for a bilingual advantage, either in relation to control or globally. Primarily there is no difference in performance across groups, but there is occasionally better performance by monolinguals or persons dominant in the language being tested, and in one case-in one condition and in one age group-lower performance by the monolinguals. The lack of evidence for a bilingual advantage in these simultaneous and early sequential bilinguals suggests the need for much closer scrutiny of what type of bilingual might demonstrate the reported effects, under what conditions, and why.

Expanded HIV testing in high-prevalence areas in England: results of a 2012 audit of sexual health commissioners

OBJECTIVES

The aim of the study was to examine whether UK HIV testing guidelines which recommend the expansion of HIV testing in high HIV prevalence areas have been implemented in England.

METHODS

An online survey tool was used to conduct an audit of sexual health commissioners in 40 high HIV prevalence areas (diagnosed prevalence > 2 per 1000) between May and June 2012. Responders were asked to provide details of expanded HIV testing programmes that they had commissioned in nontraditional settings and perceived barriers and facilitators involved in introducing expanded testing.

RESULTS

The response rate was 88% (35 of 40). Against the key audit standards, 31% (11 of 35) of areas had commissioned routine testing of new registrants in general practice, and 14% (five of 35) routine testing of general medical admissions. The majority of responders (80%; 28 of 35) had commissioned some form of expanded testing, often targeted at risk groups. The most common setting for commissioning of testing was the community (51%; 18 of 35), followed by general practice (49%; 17 of 35) and hospital departments (36%; 13 of 35). A minority (11%; four of 35) of responders had commissioned testing in all three settings. Where testing in general practice took place this was typically in a minority of practices (median 10-20%). Most (77%; 27 of 35) expected the rate of HIV testing to increase over the next year, but lack of resources was cited as a barrier to testing by 94% (33 of 35) of responders.

CONCLUSIONS

Not all high HIV prevalence areas in England have fully implemented testing guidelines. Scale-up of existing programmes and continued expansion of testing into new settings will be necessary to achieve this.

Perspectives on communicating risks of chemicals

The Agrochemicals Division symposium "Perfecting Communication of Chemical Risk", held at the 244th National Meeting and Exposition of the American Chemical Society in Philadelphia, PA, August 19-23, 2012, is summarized. The symposium, organized by James Seiber, Kevin Armbrust, John Johnston, Ivan Kennedy, Thomas Potter, and Keith Solomon, included discussion of better techniques for communicating risks, lessons from past experiences, and case studies, together with proposals to improve these techniques and their communication to the public as effective information. The case studies included risks of agricultural biotechnology, an organoarsenical (Roxarsone) in animal feed, petroleum spill-derived contamination of seafood, role of biomonitoring and other exposure assessment techniques, soil fumigants, implications of listing endosulfan as a persistant organic pollutant (POP), and diuron herbicide in runoff, including use of catchment basins to limit runoff to coastal ecozones and the Great Barrier Reef. The symposium attracted chemical risk managers including ecotoxicologists, environmental chemists, agrochemists, ecosystem managers, and regulators needing better techniques that could feed into better communication of chemical risks. Policy issues related to regulation of chemical safety as well as the role of international conventions were also presented. The symposium was broadcast via webinar to an audience outside the ACS Meeting venue.

Computer-aided molecular modeling study on antibody recognition of small molecules: an immunoassay for triazine herbicides

Most immunoassays for determination of small molecules are still designed on the basis of the "trial and error" method, due to the lack of understanding of antibody recognition. In the present study, we developed a heterologous indirect competitive enzyme-linked immunosorbent assay for determination of triazine herbicides, with limits of detection for 11 triazines ranging from 0.05 to 29.4 μg/L. Mechanisms of the antigen-antibody interaction were studied by computer-aided molecular modeling (CAMM)-based quantitative structure-activity relationship analyses. Co-effects of the analytes' substructural hydrophobic, electrostatic, and steric fields on antibody recognition were further revealed. Hydrophobicity of the antigens was demonstrated to have the most important impact. Even less exposed substituents provided hydrophobic force to the antigen-antibody interaction. Dislocated orientation of analyte functional groups could lead to steric hindrance and hydrophobic misleading of antibody recognition. This may happen even when the antigens contained the same substituent as the hapten. Frontier orbital energies also affect the reaction significantly. This study highlights of the power of CAMM-based analyses, providing insights into antibody recognition of small molecules.

Immunoassay for phenylurea herbicides: application of molecular modeling and quantitative structure-activity relationship analysis on an antigen-antibody interaction study

An indirect competitive enzyme-linked immunosorbent assay (icELISA) for 12 phenylurea herbicides (PUHs) was established with the half-maximum inhibition concentration (IC(50)) of 1.7-920.7 μg L(-1). A method of computer-aided molecular modeling was established in quantitative structure-activity relationship (QSAR) studies to obtain a deeper insight into the PUHs' antibody interactions on how and which molecular properties of the analytes quantitatively affect the antibody recognition. A two-dimensional (2D)-QSAR model based on the Hansch equation and a hologram QSAR (HQSAR) model were constructed, and both showed highly predictive abilities with cross-validation q(2) values of 0.820 and 0.752, respectively. It was revealed that the most important impact factor of the antibody recognition was the PUHs' hydrophobicity (log P), which provided a quadratic correlation to the antibody recognition. Hapten-carrier linking groups were less exposed to antibodies during immunization; thus, groups of the analytes in the same position were generally considered to be less contributive to antibody recognition during immunoassay. But the results of substructure-level analysis showed that these groups played an important role in the antigen-antibody interaction. In addition, the frontier-orbital energy parameter E(LUMO) was also demonstrated as a related determinant for this reaction. In short, the result demonstrated that the hydrophobicity and the lowest unoccupied molecular orbital energy (E(LUMO)) of PUH molecules were mainly responsible for antibody recognition.

Survey of Vietnamese peanuts, corn and soil for the presence of Aspergillus flavus and Aspergillus parasiticus

Aspergillus flavus and Aspergillus parasiticus cause perennial infection of agriculturally important crops in tropical and subtropical areas. Invasion of crops by these fungi may result in contamination of food and feed by potent carcinogenic aflatoxins. Consumption of aflatoxin contaminated foods is a recognised risk factor for human hepatocellular carcinoma (HCC) and may contribute to the high incidence of HCC in Southeast Asia. This study conducted a survey of Vietnamese crops (peanuts and corn) and soil for the presence of aflatoxigenic fungi and used microsatellite markers to investigate the genetic diversity of Vietnamese Aspergillus strains. From a total of 85 samples comprising peanut (25), corn (45) and soil (15), 106 strains were isolated. Identification of strains by colony morphology and aflatoxin production found all Vietnamese strains to be A. flavus with no A. parasiticus isolated. A. flavus was present in 36.0% of peanut samples, 31.1% of corn samples, 27.3% of farmed soil samples and was not found in virgin soil samples. Twenty-five per cent of the strains produced aflatoxins. Microsatellite analysis revealed a high level of genetic diversity in the Vietnamese A. flavus population. Clustering, based on microsatellite genotype, was unrelated to aflatoxin production, geographic origin or substrate origin.

Survey of Vietnamese coffee beans for the presence of ochratoxigenic Aspergilli

Vietnamese coffee beans were investigated for the presence of ochratoxigenic Aspergilli. Ninety-three percent of the coffee samples studied were positive for A. niger. No other ochratoxigenic species were present. HPLC analysis determined that 8.7% of the A. niger strains were positive for ochratoxin A (OA) production. There was no significant difference in the level of contamination or incidence of toxigenic strains in samples that had been rejected by manual sorting and those that were destined for human consumption. No OA-producing fungi were uncovered in a fresh coffee bean sample analysed, suggesting that the OA problem most likely occurs post-harvest.

Analysis of sulphonamide residues in edible animal products: A review

The methods of analysis for sulphonamide residues in edible animal products are reviewed. Sulphonamides are widely used for therapeutic and prophylactic purposes in both humans and animals, sometimes as growth promoters as additives in animal feed. As a result of their widespread use, there is concern about whether the levels used of these drugs can generate serious problems in human health, e.g., allergic or toxic reactions. Several methods for the determination of sulphonamides have been reported in the literature and this review considers high-performance liquid chromatography (HPLC), liquid chromatography-mass spectrometry (LC/MS), gas chromatography (GC), thin-layer chromatography (TLC), high-performance capillary electrophoresis (HPCE), enzyme-linked immunosorbant assay (ELISA), biosensor immunoassay (BIA) and microbiological methods. Specific aspects of analysing sulphonamides, such as sample handling, chromatographic conditions and detection methods are discussed. Methods for drug residue monitoring should be accurate, simple, economical in both time and cost, and capable of detecting residues below the maximum residue limits (MRL). The current sulphonamide detection technologies are based on chromatographic methods or bacteriological growth inhibition. The instrumental methods such as HPLC and GC are both sensitive and specific, but are laborious and expensive. Because of the labour-intensive processes, only a few cases of GC methods applied to residue analysis have been published. These methods are suitable for confirmation but not for screening of large numbers of samples. Microbiological methods do not require highly specialized and expensive equipment. They also use highly homogeneous cell populations for testing and thus result in better assay precision. Although HPCE has powerful separation ability, the precision is poor and the instrument still needs to be improved. To date, this technique has not been widely applied to routine analysis. Currently, TLC has been almost replaced by other instrumental analysis. A rapid, sensitive and specific assay is required to detect positive samples in routine analysis, which can then be confirmed for the presence of sulphonamides by HPLC. Immunochemical methods such as ELISA can be simple, rapid and cost-effective, with enough sensitivity and specificity to detect small molecules. This review can be considered as a basis for further research aimed at identifying the most efficient approaches.

Strabismus in infants of opiate-dependent mothers

AIM

At a follow-up clinic for infants of opiate-dependent mothers it was noted that more infants than expected developed strabismus. This study aimed to assess the prevalence of strabismus and the need for active strabismus surveillance in this population.

METHODS

Consecutive infants of opiate-dependent mothers born over an 18 mo period were recalled for ophthalmological assessment by an ophthalmologist and orthoptist. Those unable to attend were surveyed by telephone using a questionnaire.

RESULTS

49 (69%) of the 71 eligible infants were recalled at a mean age of 21 mo (range 6-39); 29 had a full ophthalmological examination and the remaining 20 completed the questionnaire only. Seven (14%) of the 49 recalled infants had strabismus on examination; 4 needed glasses or patching. A further seven (14%) had a history of intermittent strabismus but declined formal examination. Another child had significant hypermetropia without strabismus. The mean age at which strabismus was observed was 8.3 mo (range birth to 19 mo). The presence of strabismus was not significantly influenced by conditions at birth, maternal drug doses, family history or need for or duration of abstinence treatment.

CONCLUSION

The rate of strabismus in infants of opiate-dependent mothers was at least 10 times that in the general population. As attendance at follow-up is often poor, paediatricians should be aware of the association to encourage opportunistic assessment and ophthalmological surveillance of this population.

The new chimaera: the industrialization of organ transplantation. International Forum for Transplant Ethics

Clinical organ transplantation has evolved through advances in patient care in parallel with investigations in associated biologies. It has developed from a cottage industry to an important medical specialty driven increasingly by the availability of newer and more effective immunosuppressive drugs, and dependent on consistently close collaborations between university-based clinical scientists and the pharmaceutical industry. Particularly during the past decade, however, this industry has undergone striking changes, consolidating into huge multi-national corporations, each competing for patients, their doctors, and for support of the allied hospitals. Because of the growth of "Big Pharma," the relationship between academia and industry has changed. There have been many advantages to such mutually dependent interactions. A combination of university-based expertise and the specialized knowledge and resources of industry have produced important scientific gains in drug development. Commercial sponsorship of applied research has been crucial. The orchestration of multicenter controlled clinical drug trials has provided invaluable information about the effectiveness of newer agents. But there are also disadvantages of increasing concern. Indeed, the power of "Big Pharma" in many medical fields including transplantation is such that presentation of data can be delayed, adverse results withheld, and individual investigations hampered. Clinical trials may be protracted to stifle competition. Monetary considerations may transcend common sense. Several measures to enhance the clinical relationship between the pharmaceutical industry and those involved with organ transplantation are suggested, particularly the use of third party advisors in the production of clinical trials, support for more basic research and in the dissemination of results. In this way, the increasingly problematic phenomenon of commercialization of the field of transplantation can be tempered and controlled.

Occupational exposure to HIV and post-exposure prophylaxis in healthcare workers

Healthcare workers are at risk of occupationally acquired HIV infection primarily due to percutaneous exposure to HIV infected blood. The average risk of HIV transmission after such exposure is approximately 0.3%. There is evidence of higher risk for exposures involving an increased volume of blood (deep injury, injury with a device visibly contaminated with source patient's blood and a procedure which involved a needle placed in the source patient's artery or vein) and exposures to source patients with a high viral load. Triple therapy with two nucleoside analogues (zidovudine, lamivudine) and a protease inhibitor (indinavir) is now widely used for post-exposure prophylaxis following occupational exposure to HIV. Most of the evidence for the efficacy of prophylaxis is based on zidovudine monotherapy. Little is known about the long-term toxicity of these drugs in non-infected individuals. Their use in these circumstances requires careful assessment of possible risks and benefits.

Initial paclitaxel improves outcome compared with CMFP combination chemotherapy as front-line therapy in untreated metastatic breast cancer

PURPOSE

To determine the place of single-agent paclitaxel compared with nonanthracycline combination chemotherapy as front-line therapy in metastatic breast cancer.

PATIENTS AND METHODS

Patients with previously untreated metastatic breast cancer were randomized to receive either paclitaxel 200 mg/m(2) intravenously (IV) over 3 hours for eight cycles (24 weeks) or standard cyclophosphamide 100 mg/m(2)/d orally on days 1 to 14, methotrexate 40 mg/m(2) IV on days 1 and 8, fluorouracil 600 mg/m(2) IV on days 1 and 8, and prednisone 40 mg/m(2)/d orally on days 1 to 14 (CMFP) for six cycles (24 weeks) with epirubicin recommended as second-line therapy.

RESULTS

A total of 209 eligible patients were randomized with a median survival duration of 17.3 months for paclitaxel and 13.9 months for CMFP. Multivariate analysis showed that patients who received paclitaxel survived significantly longer than those who received CMFP (P =.025). Paclitaxel produced significantly less severe leukopenia, thrombocytopenia, mucositis, documented infections (all P <.001), nausea or vomiting (P =.003), and fever without documented infection (P =.007), and less hospitalization for febrile neutropenia than did CMFP (P =.001). Alopecia, peripheral neuropathy, and myalgia or arthralgia were more severe with paclitaxel (all P <.0001). Overall, quality of life was similar for both treatments (P > = .07).

CONCLUSION

Initial paclitaxel was associated with significantly less myelosuppression and fewer infections, with longer survival and similar quality of life and control of metastatic breast cancer compared with CMFP.

Pamidronate reduces skeletal morbidity in women with advanced breast cancer and lytic bone lesions: a randomized, placebo-controlled trial. Protocol 18 Aredia Breast Cancer Study Group

PURPOSE

To assess whether pamidronate can reduce the frequency of skeletal morbidity in women with lytic bone metastases from breast cancer treated with hormone therapy.

PATIENTS AND METHODS

Three hundred seventy-two women with breast cancer who had at least one lytic bone lesion and who were receiving hormonal therapy were randomized to receive 90 mg of pamidronate or placebo as a 2-hour intravenous infusion given in double-blind fashion every 4 weeks for 24 cycles. Patients were evaluated for skeletal complications: pathologic fractures, spinal cord compression, irradiation of or surgery on bone, or hypercalcemia. The skeletal morbidity rate (the ratio of the number of skeletal complications to the time on trial) was the primary efficacy variable. Bone pain, use of analgesics, quality of life, performance status, bone tumor response, and biochemical parameters were also evaluated.

RESULTS

One hundred eighty-two patients who received pamidronate and 189 who received placebo were assessable. The skeletal morbidity rate was significantly reduced at 12, 18, and 24 cycles in patients treated with 90 mg of pamidronate (P = .028, .023, and .008, respectively). At 24 cycles, the proportion of patients having had any skeletal complication was 56% in the pamidronate group and 67% in the placebo group (P = .027). The time to the first skeletal complication was longer for patients receiving pamidronate than for those given placebo (P = .049). There was no statistical difference in survival or in objective bone response rate. Pamidronate was well tolerated.

CONCLUSION

Treatment with 90 mg of pamidronate as a 2-hour intravenous infusion every 4 weeks in addition to hormonal therapy significantly reduces skeletal morbidity from osteolytic metastases.

Facilitating return to practice

The government has recently announced its intention to recruit nurses back into the profession. In this article, the authors describe an initiative undertaken by their trust to facilitate return to practice programmes, outlining the programme objectives and outcomes to date.

ATP is released from rabbit urinary bladder epithelial cells by hydrostatic pressure changes--a possible sensory mechanism?

1. The responses of rabbit urinary bladder to hydrostatic pressure changes and to electrical stimulation have been investigated using both the Ussing chamber and a superfusion apparatus. These experiments enabled us to monitor changes in both ionic transport across the tissue and cellular ATP release from it. 2. The urinary bladder of the rabbit maintains an electrical potential difference across its wall as a result largely of active sodium transport from the urinary (mucosal) to the serosal surface. 3. Small hydrostatic pressure differences produced by removal of bathing fluid from one side of the tissue caused reproducible changes in both potential difference and short-circuit current. The magnitude of these changes increases as the volume of fluid removed increases. 3. Amiloride on the mucosal (urinary), but not the serosal, surface of the membrane reduces the transepithelial potential difference and short-circuit current with an IC50 of 300 nM. Amiloride reduces the size of, but does not abolish, transepithelial potential changes caused by alterations in hydrostatic pressure. 4. Field electrical stimulation of strips of bladder tissue produces a reproducible release of ATP. Such release was demonstrated to occur largely from urothelial cells and is apparently non-vesicular as it increases in the absence of calcium and is not abolished by tetrodotoxin. 5. It is proposed that ATP is released from the urothelium as a sensory mediator for the degree of distension of the rabbit urinary bladder and other sensory modalities.

A randomized study of paclitaxel versus cyclophosphamide/methotrexate/5-fluorouracil/prednisone in previously untreated patients with advanced breast cancer: preliminary results. Taxol Investigational Trials Group, Australia/New Zealand

When administered as a single agent to previously treated patients with advanced breast cancer, paclitaxel (Taxol; Bristol-Myers Squibb Company, Princeton, NJ) has good activity. This trial was undertaken to compare paclitaxel with standard chemotherapy as front-line treatment for this disease. Patients with measurable or evaluable metastatic breast cancer, no prior chemotherapy for metastatic disease, and Eastern Cooperative Oncology Group performance status of 0 to 2 were randomized to receive either paclitaxel 200 mg/m2 intravenously over 3 hours for eight cycles over 24 weeks or standard treatment with oral cyclophosphamide 100 mg/m2/d days 1 to 14, intravenous methotrexate 40 mg/m2 days 1 and 8, intravenous 5-fluorouracil 600 mg/m2 days 1 and 8, and oral prednisone 40 mg/m2 daily days 1 to 14 (CMFP) for six cycles over 24 weeks. Patients whose disease progressed or relapsed were recommended for second-line therapy with epirubicin. Accrual has been completed with 209 patients randomized, and an interim analysis of the first 100 patients is reported here. Analysis of quality of life, assessed by the linear analogue scale and overall quality of life indices, is ongoing. Objective response occurred in 31% (confidence interval, 19% to 45%) with paclitaxel and 35% (confidence interval, 22% to 51%) with CMFP, with stable disease in an additional 33% and 29%, respectively. Median time to progression was 5.5 months with paclitaxel and 6.4 months with CMFP, with a median survival of 17.3 months for patients treated with paclitaxel and 11.3 months for those given CMFP. Grades 3 and 4 neutropenia occurred in 64% of patients with paclitaxel and 63% with CMFP. However, febrile neutropenia was the primary reason for hospitalization in 1% of paclitaxel courses, compared with 8% with CMFP. Major infections (World Health Organization grade 4) were seen in 7% of patients treated with CMFP, but in none of those given paclitaxel. Moderate or severe mucositis occurred in 13% of paclitaxel and 27% of CMFP patients. Alopecia and peripheral neuropathy were more common with paclitaxel. Quality of life assessments in the first 100 patients suggest better overall results for those treated with paclitaxel compared with CMFP. Preliminary analyses suggest that single-agent paclitaxel is well tolerated and provides control of metastatic cancer comparable to that of CMFP combination therapy when used as front-line therapy in an outpatient setting.

Paclitaxel as first-line treatment for metastatic breast cancer. The Taxol Investigational Trials Group, Australia and New Zealand

When administered as a single agent in pretreated patients with advanced breast cancer, paclitaxel (Taxol) exhibits remarkable antitumor activity. This trial was undertaken to compare paclitaxel with standard chemotherapy as front-line therapy for this disease. Patients with measurable or evaluable metastatic breast cancer, no prior chemotherapy for metastatic disease, and an Eastern Cooperative Oncology Group performance status of 0 to 2 were randomized to receive paclitaxel 200 mg/m2 intravenously over 3 hours for eight cycles (6 months) or standard treatment with oral cyclophosphamide (Cytoxan) 100 mg/m2/d days 1 through 14, intravenous methotrexate 40 mg/ m2 days 1 and 8, intravenous 5-fluorouracil 600 mg/m2 days 1 and 8, and oral prednisolone 40 mg/m2/d (CMFP) days 1 through 14 for six cycles (6 months). Patients whose disease progressed or relapsed were recommended to receive second-line epirubicin. Accrual has been completed with 208 patients randomized, but a preplanned interim analysis of the first 100 patients is reported here. Analysis of quality of life, assessed by a linear analogue scale and overall quality of life indices, is ongoing. Objective response occurred in 31% (confidence interval, 19% to 45%) with paclitaxel and 35% (confidence interval, 22% to 51%) with CMFP with stable disease in an additional 33% and 29%, respectively. Median time to progression was 5.5 months for paclitaxel-treated patients and 6.4 months for those given CMFP, with median survival durations of 17.3 and 11.3 months, respectively. Grades 3 and 4 neutropenia occurred in 64% of patients treated with paclitaxel and in 63% treated with CMFP. However, febrile neutropenia was the primary reason for hospitalization in 1% of paclitaxel courses, compared with 8% of CMFP courses. Nine percent of the patients had major infections with CMFP, but none were seen with paclitaxel. Moderate or severe mucositis occurred in 13% of paclitaxel-treated and 27% of CMFP-treated patients. Alopecia and peripheral neuropathy were more common with paclitaxel. Quality of life assessments in the first 100 patients suggest better overall results on paclitaxel treatment as compared with CMFP. Preliminary analyses suggest that single-agent paclitaxel is well tolerated and provides comparable control of metastatic cancer to CMFP combination therapy when used as front-line treatment.

New insights on P2X purinoceptors

Significant advances in understanding of P2X purinoceptor pharmacology have been made in the last few years. The limitations of nucleotide agonists as drug tools have now been amply demonstrated. Fortunately, inhibitors of the degrading ecto-ATPase enzymes are becoming available and it has become apparent that the complete removal of all divalent cations can be used experimentally in some systems to prevent nucleotide breakdown. Despite these issues, convincing evidence for P2X receptor heterogeneity, from data with agonists, has recently been reported. A number of new antagonists at P2X purinoceptors have also recently been described which to some degree appear to be more specific and useful than earlier antagonists like suramin. It is now apparent that suramin is a poor antagonist of ATP in many tissues because it potently inhibits ATPase activity at similar concentrations to those at which it blocks the P2X purinoceptor. Advances in the use of radiolabelled nucleotides as radioligands for binding studies has allowed the demonstration of P2X purinoceptors in a variety of tissues throughout the body including the brain. These studies have also provided evidence for receptor heterogeneity. Excitingly, two P2X purinoceptor genes have been cloned but operational studies suggest that more than two types exist. The cloning studies have also demonstrated a unique structure for the P2X purinoceptor which differentiates it from all other ligand-gated ion channel receptors. Further studies on P2X purinoceptor operation and structure are needed to help resolve controversies alluded to regarding the characterization and classification of nucleotide receptors. Hopefully such studies will also lead to a better understanding of the physiological and pathological importance of ATP and its activation of P2X purinoceptors. This will require the identification of better drug tools, in particular antagonists which may also provide the basis for novel therapeutic agents.

Implantation of sutured posterior chamber intraocular lenses

We describe a technique for implanting sutured posterior chamber intraocular lenses. Results of a small series using this technique in different clinical situations with at least 12 months follow-up are presented.

Effects of divalent cations on the potency of ATP and related agonists in the rat isolated vagus nerve: implications for P2 purinoceptor classification

1. By use of a 'grease-gap' technique, the depolarizing effects of adenosine 5'-triphosphate (ATP) and ATP analogues on the rat isolated vagus nerve were determined in normal and in Ca2+/Mg(2+)-free (+ 1 x 10(-3) M ethylenediamine tetraacetic acid) physiological salt solution (PSS). 2. In normal PSS, ATP produced concentration-dependent depolarization responses but the concentration-effect curve to ATP was incomplete and a maximum effect was not achieved. The threshold concentration for depolarization was 1 x 10(-5) M and at the highest concentration tested (1 x 10(-3) M) the peak amplitude of the response to ATP only amounted to 71% of the depolarization produced by a near maximal response to 5-hydroxytryptamine (5-HT, 1 x 10(-5) M). 3. In Ca2+/Mg(2+)-free PSS, ATP produced depolarization responses at much lower concentrations and of markedly larger amplitude. Under these conditions, the threshold concentration for depolarization was 1-3 x 10(-7) M and the maximal response to ATP amounted to 526% of the response to 5-HT (1 x 10(-5) M) in normal PSS. The concentration-effect curve to ATP was sigmoid, with a defined maximum effect and a mean EC50 value of 1.2 x 10(-6) M. 4. In contrast to the effects on responses to ATP, the absence of divalent cations in the PSS did not modify the effective concentrations of either alpha, beta-methylene ATP or 5-HT. However, the maximum responses to both alpha, beta-methylene ATP and 5-HT were significantly increased in Ca2+/Mg(2+)-free PSS. 5. The depolarizing effects of several analogues of ATP were determined in Ca2+/Mg2+-free PSS.ATP-gamma-S and 2-methylthioATP were of similar potency to ATP (respective equi-effective molar ratios(EMRs) of 1.9 and 1.3, where ATP = 1) and similar maximum responses were obtained. Alpha, beta-MethyleneATP, beta, gamma-methylene ATP and ,beta, gamma-imido ATP were considerably less potent than ATP, analysis yielding mean EMRs of 48.9, 85.0 and 60.0, respectively. Maximum responses to these latter three agonists were not obtained at the highest concentrations tested (1 x 10-4-3 X 10- M). Benzoyl ATP, adenosine 5'-0-(2-thiodiphosphate) and adenosine diphosphate produced only small depolarizing responses at high concentrations (>1 x 10-4 M). Adenosine monophosphate, adenosine and uridine S'-triphosphate each had little or no depolarizing effect in Ca2+/Mg2+-free PSS.6. These data demonstrate that in the absence of divalent cations the excitatory actions of some, but not all, purine nucleotides in the rat vagus nerve are markedly potentiated. In Ca2+/Mg2+-free PSS, the rank order of agonist potencies was ATP = 2-methylthioATP = ATP-gamma-S>> alpha,beta-methylene ATP = beta, gamma imido ATP = P,y-methylene ATP. These findings are in stark contrast to our previous observations in normal PSS where the rank order of agonist potencies for these nucleotides was alpha,beta-methyleneATP> ATP-gamma-S > beta,gamma-imido ATP = beta,gamma-methylene ATP> 2-methylthioATP> ATP.7. We suggest that the two different rank orders of potency can be explained by differential metabolism involving Ca2+/Mg2+-dependent ectonucleotidases. If so, these data indicate that ATP and 2-methylthioATP are inherently more potent than alpha,beta-methylene ATP as agonists at neuronal P2X purinoceptors in the rat vagus nerve. The possible implications of these findings to the present system for subclassifying P2 purinoceptors are profound.

Evidence for the presence of two types of P2 purinoceptor in the guinea-pig ileal longitudinal smooth muscle preparation

The effects of some agonists acting at P2 purinoceptors on guinea-pig isolated ileum longitudinal smooth muscle have been examined. The preparation contracted in response to ATP, alpha,beta-methylene ATP and 2-methylthio ATP, but not UTP. In this respect, alpha,beta-methylene ATP and 2-methylthio ATP were approximately equipotent and both were 10-50 times more active than ATP. Responses to alpha,beta-methylene ATP, but not 2-methylthio ATP or ATP, were antagonised by atropine and tetrodotoxin, suggesting that alpha,beta-methylene ATP activates cholinergic nerves in the ileum, whilst the other two compounds act on the smooth muscle. Two other purine nucleotide analogues, beta,gamma-methylene ATP and beta,gamma-imido ATP, did not cause contraction. However, both compounds antagonised responses to alpha,beta-methylene ATP, but not those to 2-methylthio ATP. Suramin antagonised responses to both alpha,beta-methylene ATP and 2-methylthio ATP, whilst Cibacron blue was without effect on responses to either agonist. We conclude that the purinoceptor on cholinergic nerves has some of the characteristics of the P2x purinoceptor, whilst the purinoceptor on ileal smooth muscle has some of the characteristics of the P2Y purinoceptor. However, further work will be necessary before definitive classification is possible.

The use of antagonists to characterize the receptors mediating depolarization of the rat isolated vagus nerve by alpha, beta-methylene adenosine 5'-triphosphate

1. We have previously found that the P2x-purinoceptor agonist, alpha, beta-methylene adenosine 5'-triphosphate (alpha, beta-methylene ATP), depolarizes the rat cervical vagus nerve, measured with a 'grease-gap' extracellular recording technique. This effect was attenuated by the P2 purinoceptor antagonist, suramin. In the present study we have investigated in more detail the antagonism produced by suramin and have also investigated the actions of two other putative P2 purinoceptor antagonists, cibacron blue and pyridoxal-phosphate-6-azophenyl-2', 5'-disulphonic acid (iso-PPADS). Furthermore, we have studied the interactions between suramin and cibacron blue or iso-PPADS in an attempt to determine whether these antagonists act at a common receptor site. 2. Suramin (1 x 10(-5)-1 x 10(-4) M) produced reversible, concentration-related rightward displacements of the concentration-effect curve to alpha, beta-methylene ATP. Schild analysis of this antagonism yielded a pA2 value of 5.90 with a slope value of 0.47. 3. Cibacron blue (3 x 10(-5)-1 x 10(-4) M) also antagonized depolarizations induced by alpha, beta-methylene ATP. The antagonistic effects of cibacron blue were slow to reach equilibrium but could be readily reversed on washout. At low concentrations for antagonism, cibacron blue (1 x 10(-5) M and 3 x 10(-5) M) produced enhancement of the maximal response to alpha, beta-methylene ATP. At the highest concentration tested (1 x 10(-4) M) the concentration-effect curve to alpha, beta-methylene ATP was shifted to the right in a parallel manner, yielding a pKB estimate of 4.96. 4. Iso-PPADS (1 X 10-6 1 X 10-5- M) produced a concentration-related depression in the maxima ofthe concentration-effect curves to alpha,beta-methylene ATP. Analysis of these data by a double reciprocal plot yielded a pKB estimate of 6.02. This profile of insurmountable antagonism could not be attributed to irreversible binding of iso-PPADS to the receptor since the effect of iso-PPADS could be reversed on washing, albeit slowly.5. In the presence of suramin (1 x 10-4 M), cibacron blue (1 x 10-4 M) produced no further rightward displacement of the alpha,beta-methylene ATP concentration-effect curve. The mean agonist concentration ratios in the presence of suramin or cibacron blue alone (11.7 and 10.3, respectively) were not significantly different from the mean concentration-ratio in the presence of both antagonists (11.8). This finding suggests that high concentrations of alpha,beta-methylene ATP activate a receptor population which is resistant to blockade by either antagonist.6. The antagonistic effect of iso-PPADS (1 x 10-5 M) was partially attenuated by suramin (1I x 10-4 M).It is possible that this interaction reflects a slow dissociation of iso-PPADS from the receptor with which suramin and alpha,beta-methylene ATP interact.7. Suramin, cibacron blue or iso-PPADS had no marked effect on depolarization produced by 5-hydroxytryptamine (5-HT, 1 x 10-7-3 x 10-5 M), indicating their specificity in antagonizing responses to alpha, beta-methylene ATP.8. Responses to alpha,beta-methylene ATP were not antagonized by 8-para-sulphophenyltheophylline (3 x 10-5M), ondansetron (1 x 10-7 M), bicuculline (1 x I0-5 M), phentolamine (1 X 10-6 M) or hexamethonium(1 X 10-4 M), which are antagonists at P1-purinoceptors, 5-HT3 receptors, GABAA receptors, a-adrenoceptors and nicotinic cholinoceptors, respectively, thereby excluding the involvement of these receptors.Indomethacin (3 X 10-6 M) had no effect on responses to alpha,beta-methylene ATP.9. The results obtained with three purinoceptor antagonists confirm and extend our original supposition that alpha,beta-methylene ATP-induced depolarization of the rat vagus nerve is mediated predominantly via P2 purinoceptors, thought to be of the P2,X subtype. The finding that responses induced by high concentrations of agonist were resistant to blockade by suramin and cibacron blue, but could be attenuated by iso-PPADS, adds further weight to our speculation that the purinoceptor population in the rat vagus nerve is heterogeneous.

Characterization of purinoceptors mediating depolarization of rat isolated vagus nerve

1. As part of a broader study to characterize neuronal purinoceptors, the effects of adenosine 5'-triphosphate (ATP) and a range of ATP analogues were investigated on the extracellularly recorded membrane potential of the rat isolated vagus nerve, using a 'grease-gap' technique. 2. ATP evoked depolarization of the rat vagus nerve. The concentration-effect curve to ATP was not monophasic: at the lower concentrations (1 x 10(-5)-1 x 10(-3) M) the curve was shallow (< 50% of the near maximal response to 5-hydroxytryptamine (5-HT)) whilst at higher concentrations the relationship between concentration and amplitude of depolarization was steeper (> 135% of the response to 5-HT at the highest concentration tested, 1 x 10(-2) M). On washout of the high drug concentrations large after-hyperpolarizations were often observed. 3. alpha,beta-methylene ATP (1 x 10(-6)-3 x 10(-4) M), beta,gamma-methylene ATP (1 x 10(-6)-1 x 10(-3) M), and 5'-adenylylimidodiphosphate (beta,gamma-imido ATP; 1 x 10(-6)-1 x 10(-3) M) were all more potent than ATP and produced large depolarizations of the rat vagus nerve at the highest concentrations tested (> 150% of the response to 5-HT). The overall rank order of potency was alpha,beta-methylene ATP > beta,gamma-methylene ATP = beta,gamma-imido ATP > ATP. 4. In contrast, 2-methylthio ATP (1 x 10(-6)-1 x 10(-3) M) produced relatively small depolarizations (< 100% of the response to 5-HT). As was the case with low concentrations of ATP, the concentration-effect curve to 2-methylthio ATP was very shallow. 5. Adenosine 5'-diphosphate (ADP), adenosine 5'-monophosphate (AMP), adenosine and adenosine 5'-O-(2-thiodiphosphate) (ADP-beta-s; all 1 x 10-6 1 x 10-3M) evoked only small depolarizations of the vagus nerve, amounting to 47 +/- 2.5%, 40.8 +/- 7.8%, 33.7 +/- 3.3% and 62.4 +/- 12.7% of the response to 5-HT, respectively. Uridine 5'-triphosphate (UTP; 1 X 10-6 1 X 10-3M) was inactive.6. The P2 purinoceptor antagonist, suramin (1 x 10-5-M-1 X 10-4 M), antagonized responses to alpha-beta-methylene ATP. The nature of this antagonism was not, however, consistent with simple competitive kinetics between agonist and antagonist. Depolarizations produced by beta,gamma-methylene ATP and beta,gamma-imido ATP were also attenuated by suramin (1 x 10-4 M), but in contrast, suramin had no effect on responses to ADP, 2-methylthio ATP, ADP-beta-S or 5-HT.7. In addition to its antagonist effects, suramin (10-4 M) markedly increased the maximum amplitude of the depolarization produced by ATP.8. It is concluded that a heterogeneous receptor population mediates depolarization of the rat vagus nerve by purine nucleotides. Importantly, the large amplitude depolarizations to alpha,beta-methylene ATP,beta,gamma-methylene ATP and beta,gamma-imido ATP are mediated via receptors that share many characteristics of the classical P2, receptor. In contrast, the relatively small depolarizing effects of ADP, ADP-beta-S and 2-methylthio ATP were suramin-resistant. Although it appears that other purinoceptors are present,these data suggest that the rat vagus nerve may serve as a useful preparation for studying the pharmacology of neuronal P2x receptors.

Functional characterization of three adenosine receptor types

1. The purpose of the present study was to classify adenosine receptors into A1 and A2 subtypes in a wide range of isolated tissues and cell types (rat adipocytes and atria, guinea-pig ileum and atria (A1); guinea-pig aorta, dog coronary artery and human platelets and neutrophils (A2)) using the R- and S-diastereoisomers of N-phenylisopropyladenosine (PIA), N-cyclopentyladenosine (CPA), the novel compound, N-[(1S,trans)-2-hydroxycyclopentyl]adenosine (GR79236), N-[(2-methylphenyl)methyl]adenosine (metrifudil), 2-(phenylamino)adenosine (CV1808), and 2[[2-[4-(2-carboxyethyl)phenyl]ethyl]amino]-N- ethylcarboxamidoadenosine (CGS21680); N-ethylcarboxamidoadenosine (NECA) was used as a standard. 2. Results obtained in all tissue preparations previously reported to contain A1-receptors could be described by a single rank order of agonist potency: CPA > or = GR79236, R-PIA > or = NECA >> S-PAI > or = metrifudil > or = CV1808, CGS21680. 3. In contrast, two distinct rank orders of agonist potency were observed in preparations previously reported to contain A2-receptors. In dog coronary artery, human neutrophils and platelets the rank order of potency was: CV1808, CGS21680 > or = NECA > R-PIA > or = metrifudil > or = CPA > GR79236 S-PIA. However, in guinea-pig aorta the rank order was: NECA > metrifudil > R-PIA, CPA > CV1808, GR79236 > or = S-PIA, CGS21680. 4. The results of this study are consistent with the existence of three types of adenosine receptor: A1-and two subtypes of A2-receptor. The receptor present in dog coronary artery, human platelets and neutrophils, probably corresponds to the A2a subtype, whilst that present in the guinea-pig aorta may be of the A2b subtype.

Suppression of non-esterified fatty acids and triacylglycerol in experimental animals by the adenosine analogue GR79236

1. This is the first description of the metabolic activity of a novel adenosine A1-receptor agonist, GR79236. GR79236 inhibited catecholamine-induced lipolysis in human, rat and dog isolated adipocytes. 2. Oral administration of GR79236 (0.1-10 mg/kg) to fed rats induced minimal changes in the plasma concentration of non-esterified fatty acids and in the blood concentrations of glucose and lactate. 3. Intravenous infusion of GR79236 to fasted pithed rats, or oral administration of GR79236 to fasted conscious rats and dogs, produced time- and dose-dependent decreases in the plasma non-esterified fatty acid concentration. In the fasted rats, doses of GR79236 that lowered plasma levels of non-esterified fatty acids also produced hypotriglyceridaemia and anti-ketotic effects. 4. Only in the pithed rats were acute effects on the plasma glucose and lactate concentrations observed. Hypoglycaemia and hyperlactataemia occurred over the dose range studied (1 x 10(-11)-1 x 10(-8) mol min-1 kg-1). 5. This profile of activity suggests that compounds such as GR79236 might be agents which can be used to define the role of excessive lipolysis in experimental (and human) pathophysiology.