Implications of alternative classifications and horizontal gene transfer for bacterial taxonomy

Following the publication of the Approved Lists, there has been a tendency to regard all subsequent revisions of classification as providing improved nomenclature, to be accepted without question. This takes no account of the fact that such revisions may be based on one of three alternative concepts, phenetic, phylogenetic or polyphasic classification, sometimes leading to different, valid, but incompatible nomenclature, or that some investigations are based only on subsets of relevant taxa and on limited data, leading to incomplete and sometimes confusing revisions of nomenclature. The polyphasic approach to classification has widespread support, although there appears to be a tendency to allow comparative sequence analyses of 16S rDNA to determine classification contrary to the indications of other data. In some cases, classification is based solely on 16S rDNA data. Examples are considered. Consideration is given to the criteria by which taxa are circumscribed, particularly at the level of genus and species. It is suggested that there is a need for reconciliation of the criteria by which taxa at these levels are circumscribed. Recent studies demonstrating the widespread occurrence of horizontal gene transfer suggest that there is a need for caution in monophyletic interpretations, especially when these are based on the analysis of single sequences.

Mecamylamine: new therapeutic uses and toxicity/risk profile

BACKGROUND

Mecamylamine hydrochloride was initially developed for its ganglion-blocking activity and has been marketed as an antihypertensive agent in the United States for >40 years. Several other potential therapeutic applications are being investigated, most of them focusing on the drug's ability to cross the blood-brain barrier and selectively antagonize neuronal nicotinic acetylcholine receptors. This central activity of mecamylamine is demonstrable at much lower doses than the effective antihypertensive dose, thus avoiding many of the bothersome side effects associated with the drug's inhibition of parasympathetic activity.

OBJECTIVE

Because investigations are being conducted in new patient populations, including pediatric patients, an update of the toxicity/risk profile of mecamylamine is timely. This review describes nonclinical and clinical data pertaining to the pharmacology, toxicity, and tolerability of mecamylamine, including some previously unpublished toxicology and clinical pharmacokinetics data. Potential new therapeutic applications are discussed, including the use of mecamylamine in treating autonomic dysreflexia; dependencies on nicotine, cocaine, and other substances of abuse; Tourette's syndrome; and other neuropsychiatric disorders.

METHODS

Information for this review of mecamylamine was identified through a search of MEDLINE from 1966 to the present, as well as from the master files of Merck & Co, Inc, the drug's original manufacturer, and Layton BioScience, Inc, its present manufacturer.

CONCLUSIONS

The available data concerning potential new applications of mecamylamine, although sparse, suggest that the drug's toxicity/risk profile may be much improved at lower doses.

In vitro HIV-specific CTL activity from HIV-seropositive individuals is augmented by interleukin-12 (IL-12)

IL-12 production is reduced in HIV infection, and recombinant human IL-12 (rhIL-12) augments in vitro HIV-specific proliferative responses in PBMC from HIV-seropositive individuals. To determine whether rhIL12 could also augment HIV-specific CTL responses we studied 41 HIV-seropositive individuals. Recombinant hIL-12 increased the detectable in vitro HIV-specific CD8 CTL activity of PBMC taken from HIV-seropositive individuals with CD4 counts >500 cells/microl and from some individuals with lower CD4 counts. IL-12 increased cell recovery in cultures of PBMC from HIV-seropositive individuals with CD4 counts >500 cells/microl and also increased the precursor CTL frequency. However, the increase in HIV-specific CTL activity was not due to IL-2 or IFN-gamma production or an increase in the number of cells with surface markers characteristic of CTL effector cells. This study demonstrates that rhIL-12 augments in vitro HIV-specific CTL activity and provides evidence to justify further investigation within clinical trials of this cytokine in HIV infection.

Implementing guidelines for smoking cessation advice in Australian general practice: opinions, current practices, readiness to change and perceived barriers

OBJECTIVE

The aim of this study was to ascertain opinions, current practices, likely readiness to change and perceived barriers to change among Australian GPs in order to develop a plan to implement national guidelines for smoking cessation advice.

METHOD

A postal survey of randomly selected GPs in New South Wales, Australia was carried out.

RESULTS

We received 311 returned questionnaires (73% response rate). Only 34% of respondents reported providing cessation advice during every routine consultation with a smoker, in accordance with national guidelines. Specific evidence-based approaches recommended in guidelines were under-utilized, with only 54% 'always' or 'frequently' arranging follow-up, 32% providing written materials and 28% setting a 'quit date'. Respondents were no more likely to advise quitting completely than the less effective method of nicotine fading. More than one in four respondents (28%) indicated readiness to change their behaviour. Respondents rated their patients' lack of motivation and uninterest as the most important barriers to smoking cessation advice in general practice. Neither uncertainty about effective smoking cessation strategies nor lack of reimbursement for smoking cessation advice were identified as barriers.

CONCLUSIONS

A multicomponent intervention to address suboptimal behaviour and barriers as revealed by this survey holds considerable potential to plan effective implementation of smoking cessation guidelines in general practice. The use of readiness to change as a tool to 'individualize' strategies for guideline implementation should be explored.

A revision of Rhizobium Frank 1889, with an emended description of the genus, and the inclusion of all species of Agrobacterium Conn 1942 and Allorhizobium undicola de Lajudie et al. 1998 as new combinations: Rhizobium radiobacter, R. rhizogenes, R. rubi, R. undicola and R. vitis

Rhizobium, Agrobacterium and Allorhizobium are genera within the bacterial family Rhizobiaceae, together with Sinorhizobium. The species of Agrobacterium, Agrobacterium tumefaciens (syn. Agrobacterium radiobacter), Agrobacterium rhizogenes, Agrobacterium rubi and Agrobacterium vitis, together with Allorhizobium undicola, form a monophyletic group with all Rhizobium species, based on comparative 16S rDNA analyses. Agrobacterium is an artificial genus comprising plant-pathogenic species. The monophyletic nature of Agrobacterium, Allorhizobium and Rhizobium and their common phenotypic generic circumscription support their amalgamation into a single genus, Rhizobium. Agrobacterium tumefaciens was conserved as the type species of Agrobacterium, but the epithet radiobacter would take precedence as Rhizobium radiobacter in the revised genus. The proposed new combinations are Rhizobium radiobacter, Rhizobium rhizogenes, Rhizobium rubi, Rhizobium undicola and Rhizobium vitis.

The interaction of U-73122 with the histamine H1 receptor: implications for the use of U-73122 in defining H1 receptor-coupled signalling pathways

U-73122, an N-aminosteroid homologue of N-ethylmaleimide (NEM), widely used as an inhibitor of phospholipase C, was found to be a potent inhibitor (IC50 5.5+/-0.5 microM) of the binding of [3H]mepyramine to guinea-pig cerebellar membranes. The succinimido analogue, U-73343, also inhibited the binding of [3H]mepyramine (estimated IC50 24+/-1 microM), but NEM was only a weak inhibitor, even at 10 mM. The interaction of U-73122 and U-73343 with the H1 receptor was effectively irreversible, on the time-scale of the experiment. There is no indication that reaction with a receptor thiol residue is involved in the binding of U-73122, since preincubation of membranes with 2 mM NEM did not significantly increase the IC50 for the inhibition of [3H]mepyramine binding by U-73122. We conclude that U-73122 binds to the histamine H1 receptor in the concentration range in which it acts as an inhibitor or PLC. This compromises the use of U-73122 to provide evidence that an H1 agonist action is mediated via PLC. The tight binding of U-73343 to the receptor appears to be primarily a function of the hydrophobic nature of the compound.

Postpartum headache after epidural blood patch: investigation and diagnosis

Use of an epidural blood patch to treat spinal headache after accidental dural puncture is well recognized. The high success rate associated with this practice has been questioned and it is not uncommon for patients to suffer recurring headaches after a supposedly successful blood patch. We describe a patient in labour who suffered accidental dural puncture, and whose headache was treated twice with an epidural blood patch. Despite this, the headache persisted. The case highlights the difficulty in the diagnosis of headache in the postnatal period in patients who have had regional analgesia and the importance of considering an alternative pathology, even if epidural blood patching has been successful. In this case, a diagnosis of cortical vein thrombosis was made. The incidence, presentation, aetiology and treatment of this rare condition is described.

A unique role: the peer mentor on the spinal cord team at G.F. Strong Rehab Centre

The peer mentor is a full time paid staff member of the G. F. Strong Rehab Centre Spinal Cord Program. To qualify for the position, an individual with a high lesion spinal cord injury must live a self-managed life in the community. The peer mentor's role bridges professional, lay, and client perspectives, and is a voice for both clients and staff unlike any other team member. This report focuses on the peer mentor's facilitation of communication between clients and staff and on two initiatives that promote clients' perspectives.

Laryngeal mask airway use in children with acute burns: intraoperative airway management

Paediatric patients with acute burns often require many operative procedures in short succession; yet due to inhalation injury or recent extubation their airways may be susceptible to tracheal tube induced damage. We proposed the laryngeal mask airway (LMA) as a useful airway management tool in this setting. In this prospective study, 80 eight (88) patients with mean age (+/- SD) of 7.8 +/- 4.7 years and average percentage total body surface area burned (%TBSA) of 21 +/- 18% had their airways managed with an LMA while in the operating room for 141 procedures. Twenty-five patients (28.4%) had been previously intubated for burn management and 19 (21.6%) had evidence of inhalation injury. During each procedure, the patient was evaluated for airway obstruction, laryngospasm, inability to ventilate, hypoxaemia, evidence of aspiration/regurgitation or any situation which required intraoperative manipulation/removal of the LMA. Of the 141 procedures, 122 were without airway problems. Of the remaining 19, nine required only a simple reseating of the LMA for correction. The other 10 events include arterial desaturation (n = 3), partial laryngospasm (5), airway obstruction (1) and regurgitation without aspiration (1). In each case, corrective action led to resolution of the problem with no patient morbidity. This series demonstrates the LMA is a safe and efficacious airway management device in the paediatric burn population.

Characterisation of alpha1B-adrenoceptors linked to inositol phosphate formation and calcium mobilisation in human astrocytoma U373 MG cells

The human U373 MG astrocytoma cell line has been widely used as a model system for the investigation of astrocyte function. The aim of this study was to establish which alpha1-adrenoceptors are present on these cells. The specific binding of [3H]prazosin to membranes of U373 MG cells (Bmax 32+/-3 fmol mg(-1) protein, Kd 0.27+/-0.03 nM) was inhibited in a monophasic manner by alpha1-antagonists that have different affinities for alpha1A-, alpha1B- and alpha1D-adrenoceptors. Estimates for pKi values were: prazosin 9.69+/-0.06, 5-methylurapidil 7.10+/-0.21; (+)-niguldipine 7.06+/-0.26; WB 4101 8.26+/-0.16; and BMY 7378 6.60+/-0.21. The specific binding of [3H]prazosin was reduced to low levels by pretreatment of cells with 10 microM chloroethylclonidine for 15 min. In the presence of 30 mM LiCl, 100 microM noradrenaline stimulated [3H]inositol phosphate accumulation by 2.1+/-0.1-fold of basal after 30-min incubation. The EC50 for the accumulation of [3H]IP1, the major product detected (85+/-2% of total [3H]IP1 + [3H]IP2 + [3H]IP3), was 0.38+/-0.05 microM. Noradrenaline-induced [3H]IP1 accumulation was also inhibited by alpha1-antagonists. Estimates for pKi values were: 5-methylurapidil 6.95+/-0.01; WB 4101 8.31+/-0.07; and BMY 7378 6.71+/-0.28. The accumulation of [3H]IP1 in response to 100 microM noradrenaline was not significantly affected by raising the extracellular Ca2+ concentration from 1.3 to 4 mM. Noradrenaline (100 microM) also produced an increase in intracellular Ca2+ (mean peak 86+/-5 nM above basal). Pretreatment with chloroethylclonidine (10 microM, 15 min) abolished noradrenaline-induced [3H]IP1 accumulation and Ca2+ mobilisation. Activation of the alpha1B-adrenoceptors by 10 microM phenylephrine increased [3H]thymidine uptake to 140+/-5% of control uptake. Taken together, these results indicate that U373 MG cells express a single class of alpha1-adrenoceptors, the alpha1B-subtype, which are coupled to phosphoinositide hydrolysis and calcium mobilisation, and which mediate a mitogenic response to alpha1-agonists.

Population-based cancer control: where is the greatest benefit from proven strategies to 'regain' years of life lost prematurely?

OBJECTIVE

To apply a 'health gain' approach to population-based cancer control.

METHOD

We calculated the potential years of life otherwise lost prematurely which could be 'regained' through implementation of cancer control programs for which Level I or Level II evidence already exists for population outcomes.

RESULTS

More potential years of life lost (PYLLs) would be 'regained' by enforcing a 'smoke-free' Australia than by any other possible scenario based on proven effectiveness. Even achievable scenarios for tobacco control (17% or 20% prevalence) would 'regain' more PYLL than either mammographic screening according to national policy or faecal occult blood testing (FOBT) of both men and women over 50 years for colorectal cancer.

CONCLUSIONS

As few commentators remain optimistic that more money will be allocated to health, strategic thinking for health gain needs to re-appraise resource allocation for population-based cancer control in Australia.

IMPLICATIONS

We recommend wider debate in response to our finding that, on the basis of best available evidence, the greatest potential for health gain lies less in cancer screening than fully funded tobacco control.

Aerosol and vapor control in the dental treatment room

As dental clinicians, common sense is still the best weapon for infection control--the use of antimicrobial cleaning products remains an integral component of any infection control procedure.

Strategies to improve cancer screening in general practice: are guidelines the answer?

BACKGROUND

GPs are ideally placed to recommend appropriate cancer screening for their patients. However, opportunities to discuss screening are often missed and screening procedures are not always recommended in accordance with national policy. The development of clinical practice guidelines represents one strategy for improving cancer screening in general practice.

OBJECTIVE

We aimed to ascertain Australian GPs' ratings of current clinical practice guidelines and their views of the likely usefulness of 18 strategies to improve cancer screening in general practice.

METHOD

A self-administered questionnaire was mailed to a national random sample of 1271 GPs in May 1996. Responders rated the usefulness of each of eight clinical practice guidelines current at the time of the survey. They then rated the usefulness of each of 18 strategies for support of cancer screening.

RESULTS

We received 855 completed questionnaires (a 67% response rate). There was greatest support for guidelines already available on breast and cervical cancer. The most popular strategy to improve cancer screening was seminars with experts in preventive care, rated as 'very useful' by 658 (77%), followed by NHMRC guidelines (597, 70%) and pamphlets for patients (587, 69%). There was less support for more innovative strategies including assessment and feedback (35%), case finding by nurse practitioners (11%) and academic detailing (10%).

CONCLUSION

Responders indicated that strategies involving passive dissemination of information would be most useful for improving cancer screening in general practice. Identification of an effective combination of acceptable initiatives is needed.

General practitioners' use of evidence databases

OBJECTIVE

To determine the awareness and use of the Cochrane Library and access to the Internet by general practitioners in New South Wales.

DESIGN

Cross-sectional postal survey in September 1997.

PARTICIPANTS

311 of 428 (73% response rate) randomly selected general practitioners in New South Wales.

MAIN OUTCOME MEASURES

Proportion of respondents with access to the Internet at home or at work; proportion of respondents aware of, with access to, and ever using the Cochrane Library; independent predictors of awareness of the Cochrane Library.

RESULTS

134 respondents (43%) had access to the Internet either at home or at work; 42 (14%) were "on line" at their workplace. Seventy (22%) were aware of the Cochrane Library, although only 20 (6%) had access to it and 13 (4%) had ever used it. Those in group practice and members of Divisions were independently more likely to be aware of the Cochrane Library.

CONCLUSIONS

As patient outcomes will improve with systematic implementation of evidence-based treatments, these low rates of access to useful evidence databases raise issues regarding the best ways to support general practitioners with information technology.

Influence of physician and patient gender on provision of smoking cessation advice in general practice

OBJECTIVE

To examine the association between physician and patient gender and physicians' self-reported likelihood of providing smoking cessation advice to smokers using hypothetical case scenarios in primary care.

DESIGN

Cross-sectional analysis of a self-administered questionnaire.

SUBJECTS

National random sample of Australian general practitioners (GPs).

MAIN OUTCOME MEASURES

Self-reported likelihood of advising hypothetical male and female smokers to stop smoking during a consultation for ear-syringing ("opportunistic" approach) or a dedicated preventive health "check up".

RESULTS

855 GPs returned questionnaires (67% response rate). Significantly more respondents indicated they would be "highly likely" to initiate an opportunistic discussion about smoking with a male smoker (47.8% (95% confidence intervals (CI) = 44.5 to 51.2)) than a female smoker (36.3% (95% CI = 33.1 to 39.5]). Older, male GPs were less likely to adopt an opportunistic approach to smoking cessation for patients of either sex. Respondents were more likely to recommend that a male patient return for a specific preventive health check up. Furthermore, in the context of a health check up, a greater proportion in total of respondents indicated they would be "highly likely" to discuss smoking with a man (86.9%, 95% CI = 84.5 to 89.0) than a female smoker (82.5%, 95% CI = 79.8 to 84.9).

CONCLUSIONS

As measured by physician self-report, the likelihood of advising smokers to quit during primary care consultations in Australia appears to be influenced by gender bias. Gender-sensitive strategies to support cessation activities are recommended.

Ca2+/calmodulin-mediated regulation of agonist-induced sequestration of Gq protein-coupled histamine H1 receptors in human U373 MG astrocytoma cells

We investigated the regulation by intracellular Ca2+ of agonist-induced sequestration of Gq protein-coupled histamine H1 receptors in human U373 MG astrocytoma cells. Histamine-induced sequestration of H1 receptors from the cell surface membrane was detected as the loss of [3H]mepyramine binding sites on intact cells accessible to the hydrophilic H1-receptor antagonist pirdonium. The changes in the pirdonium-sensitive binding of [3H]mepyramine were mirrored by changes in the subcellular distribution of H1 receptors detected by sucrose density gradient centrifugation. The histamine-induced sequestration of H1 receptors did not occur in hypertonic medium, in which clathrin-mediated endocytosis is known to be inhibited, but was significantly accelerated in the absence of extracellular Ca2+ or in the presence of the calmodulin antagonists W-7 and calmidazolium. Inhibitors of protein kinase C (H-7 and GF109203X), Ca2+/calmodulin-dependent protein kinase II (KN-62), or protein phosphatase 2B (FK506) did not alter the time course of H1-receptor sequestration. These results provide the first evidence that agonist-induced, clathrin-mediated sequestration of Gq protein-coupled receptors is transiently inhibited by Ca2+/calmodulin, with the result that receptors remain on the cell surface membrane during the early stage of agonist stimulation.

Improving smoking cessation advice in Australian general practice: what do GPs suggest is needed?

Smoking cessation advice from a general practitioner (GP) significantly increases quit rates among patients who smoke. However, smoking is not discussed during most routine consultations with smokers. This study describes GPs' own views about strategies to support their cessation advice. In 1997, a random sample of 311 GPs in NSW (73% response rate) completed a self-administered questionnaire about smoking cessation. Most respondents were 'very confident' about discussing the health effects of smoking (81.7%). Fewer were as confident about negotiating a quit date (21.5%) or using evidence-based smoking cessation techniques (19.3%). The top three preferred strategies to support smoking cessation advice were all resources for patients: subsidised nicotine replacement therapy (rated as 'quite useful' by 60.5%), pamphlets (55.0%) and free access to smoking cessation clinics (50.8%). Skills training (39.7%) was the preferred resource to improve practitioner effectiveness. Interventions combining skills training with patient resources are likely to be well received by GPs.

SK&F 96365 (1-[beta-[3-(4-methoxyphenyl)propoxy]-4-methoxyphenylethyl]-1H- imidazole hydrochloride) stimulates phosphoinositide hydrolysis in human U373 MG astrocytoma cells

SK&F 96365 (1-[beta-[3-(4-methoxyphenyl)propoxy]-4-methoxyphenylethyl]-1H-imi dazole hydrochloride) stimulated the accumulation of [3H]inositol monophosphates ([3H]IP1) in human U373 MG astrocytoma cells prelabelled with [3H]inositol (EC50 15 +/- 1 microM, Hill coefficient 3.8 +/- 0.4). SK&F 96365-induced accumulation of [3H]IP1 increased linearly with time, but there was no initial rapid formation of [3H]IP3. SK&F 96365 also stimulated [3H]IP1 accumulation in human HeLa cells, but only to a small extent in slices of rat cerebral cortex and guinea-pig cerebellum. SK&F 96365-induced accumulation of [3H]IP1 in U373 MG cells increased as extracellular Ca2+ was increased from nominally zero to 4 mM, but there was no evidence that SK&F 96365 induced any marked entry of Ca2+ into cells; only an inhibition of store-refilling-induced Ca2+ entry was apparent. Further, the response to SK&F 96365 was additive with that to the Ca2+ ionophore ionomycin. Depolarization of the cells with raised K+ produced only a small stimulation of phosphoinositide hydrolysis. SK&F 96365 caused the release of Ca2+ from intracellular stores in U373 MG cells (EC50 26 +/- 14 microM), but thapsigargin induced only a small accumulation of [3H]IP1. Miconazole, another N-substituted imidazole, also stimulated [3H]IP1 accumulation in U373 cells.

Breast cancer screening in Australian general practice: results of a national survey

OBJECTIVE

To determine current beliefs and knowledge about, and use of, two screening tests for breast cancer (mammography and clinical breast examination [CBE]) among general practitioners (GPs).

DESIGN, PARTICIPANTS AND SETTING

National postal survey of randomly selected GPs from throughout Australia in May 1996.

MAIN OUTCOME MEASURES

Belief in the effectiveness of each screening test in reducing premature deaths from breast cancer; recommended age group and screening interval for each test; likelihood of including each opportunistically or in a health check-up. Predictors were determined by regression analyses.

RESULTS

The response rate was 67% (855/1271). Significantly more respondents believed in the effectiveness of mammography than of CBE (92% v. 66%). About half identified women 50 years and over as the appropriate target group for mammography. Only 40% indicated they would be "highly likely" to discuss mammography opportunistically, although 82% would be "highly likely" to discuss it in a health check-up. After adjusting for confounders, female GPs were more likely to discuss mammographic screening and to advocate a biennial frequency. Older GPs and those from New South Wales were least likely to recommend mammography (consistent with the national policy). Significantly more respondents were "highly likely" to discuss CBE than mammography in a health check-up.

CONCLUSIONS

GPs are convinced of the effectiveness of mammography, but as respondents were more likely to screen by CBE than to recommend mammography in a dedicated health check-up a consistent national policy about CBE would be highly desirable.

Cellular and molecular regulation of eosinophil trafficking to the lung

Airway inflammation is central to the pathogenesis of allergic asthma, and molecules that mediate this process obviously represent targets for therapy. In the present article, we discuss our experiments, which point to CD4+ T cells and IL-5-driven eosinophilia as potential targets for the relief of bronchial hyperreactivity in late-phase asthma.

Preliminary description of biocidal (syringomycin) activity in fluorescent plant pathogenic Pseudomonas species

Strains representing the fluorescent plant pathogenic Pseudomonas spp., Ps. agarici, Ps. asplenii, Ps. avellanae, Ps. beteli, Ps. caricapapayae, Ps. cichorii, Ps. corrugata, Ps. ficuserectae, Ps. flectens, Ps. fuscovaginae, Ps. marginalis, Ps. meliae, Ps. savastanoi, Ps. syringae, Ps. tolaasii and Ps. viridiflava were tested for biocidal activity using Aspergillus niger as assay organism. Inhibitory behaviour was found in strains of Ps. asplenii, Ps. blatchfordae, Ps. cichorii, Ps. corrugata, Ps. fuscovaginae, Ps. marginalis, Ps. marginalis pv. pastinacea, Ps. syringae pv. syringae, Ps. syringae pv. aptata, Ps. syringae pv. atrofaciens, Ps. syringae pv. lapsa, Ps. tolaasii, and strains of a Pseudomonas sp. pathogenic to Actinidia, in the Ps. savastanoi genomic sp. Antifungal activity could be identified with the production of members of the syringomycin family of toxins by strains in Ps. syringae, Ps. asplenii and Ps. fuscovaginae. These toxin reactions support suggestions made elsewhere of the synonym of the latter two species. In a preliminary characterization using tests for stability to heat, protease, acid and alkaline treatments, unknown toxins consistent with syringomycin-like toxins the strains from Actinidia species. The toxins from Ps. cichorii and from Ps. corrugata differed in their reactions from all other agents. Pseudomonas tolaasii produces the antifungal compound tolaasin. The white line reaction with Ps. reactions, a test for tolaasin production by strains of Ps. tolaasii, was confirmed as specific for this compound. Some of these low molecular weight toxins may be produced by some of these plant pathogenic strains.