Distribution of a sub-class of bacterial ABC polar amino acid transporter and identification of an N-terminal region involved in solute specificity.

A new sub-class of binding protein-dependent transporter with specificity for a broad range of polar amino acids has been identified by sequence comparison, in Rhizobium leguminosarum, Rhodobacter capsulatus, Escherichia coli and Pseudomonas fluorescens. Southern blotting and PCR analysis has shown that transporters from this new sub-class are widely distributed in Gram-negative bacteria, including, in addition to the above, Citrobacter freundii, Erwinia carotovorum and Rhizobium meliloti. ABC transporters of polar amino acids can be divided into two groups: those with narrow solute specificity and the newly identified sub-class with broad solute specificity. The binding and inner membrane proteins from transporters with a broad solute specificity are larger by approximately 30% than those with a narrow solute specificity. Multiple alignment of the inner membrane proteins from all sequenced polar amino acid transporters indicates there is an N-terminal conserved region that may be involved in solute specificity. A conserved arginine or lysine at residue 30 of this region is changed to glutamate in arginine transporters. Residue 53 also has a strong correlation with the charge on the transported solute, with basic amino acid transporters replacing an aliphatic amino acid at this position with a negatively charged amino acid. The general amino acid permease from R. leguminosarum, which will transport aliphatic as well as basic and acidic amino acids, juxtaposes two prolines at residues 52 and 53 of the N-terminal conserved region.

The general amino acid permease of Rhizobium leguminosarum strain 3841 is negatively regulated by the Ntr system.

Cosmid-borne and chromosomal lacZ fusions to aapJ. aapQ and aapM were used to examine the nitrogen regulation of the general amino acid permease (Aap) of Rhizobium leguminosarum strain 3841. Transcription of the first gene of the operon (aapJ), which encodes the periplasmic binding protein, was 2-4-fold higher than aapQ and aapM, which encode the integral membrane proteins, under various growth conditions. This may be due to the presence of a putative stem loop in the intergenic region between aapJ and aapQ. All aap fusions were derepressed 3-5-fold after growth on glutamate as a nitrogen source, which effectively causes nitrogen limitation. An ntrC mutant was derepressed for transcription of the aap operon and had high rates of amino acid transport when grown on ammonia as the nitrogen source. Thus NtrC negatively regulates the aap operon, contrary to its usual role in positive gene activation. These results confirm that the aap-operon is subject to complex regulation involving both transcriptional and post-transcriptional factors.

Drink and drugs: from medical students to doctors.

Drinking and illicit drug use were assessed longitudinally in a cohort of medical students who were surveyed in the second and fifth year of their undergraduate studies and after 1 year as PRHOs. Mean alcohol consumption had increased significantly (P<0.015) over the three time points; 15.2-16.0-18.8 units/week. Experimentation with illicit drugs had increased from 50 to 63 to 65%. Although education on alcohol and illicit drugs should be part of core curriculum in medical schools, support and intervention in the workplace is also needed for individuals with alcohol and/or drug problems.

Quantification of relative afferent pupillary defects induced by posterior sub-Tenon's, peribulbar, and retrobulbar anaesthetics.

AIMS: The effect of local anaesthetics on optic nerve function can be investigated by quantifying the relative afferent pupillary defect (RAPD). METHODS: The study compared the depth of induced RAPD following posterior sub-Tenon's, retrobulbar, and peribulbar local anaesthetics using crossed polarising filters before cataract surgery (time 1 = 5 minutes), immediately after surgery (time 2 = 42 minutes (av)), and once again on the ward (time 3 = 107 minutes (av)). RESULTS: All patients developed a RAPD. There was no significant difference in the depth of RAPD between the groups at any one time period. The peribulbar group had a significantly steeper decay in RAPD from time 1 to time 2 (p = 0.014). This effect was reduced when the shorter operation time for this group was entered as a cofactor (p = 0.063). By time 3 the RAPDs for all groups had decayed similarly so that no differences could be detected. CONCLUSION: All three anaesthetic methods caused a similar level of disruption to optic nerve conduction immediately following administration and at the time of day case discharge.

An interesting byproduct of screening: assessing the effect of HRT on arterial calcification in the female breast.

Arterial calcification in the female breast (BAC) is a common but unreported finding on breast screening mammograms. Accumulating evidence suggests that BAC may have importance as a marker for generalised vascular disease. In this study, we have assessed the influence of HRT usage on the prevalence of BAC in 4400 women undergoing mammography for breast cancer screening. Significantly increased levels of breast arterial calcification were observed in women who had never used HRT compared with a group of women presently using HRT.

The causes of fever in children attending hospital in the north of England.

OBJECTIVES: Fever is a common symptom in children presenting to casualty. Identifying the seriously ill is difficult. Previous studies, mainly from North America, suggest that symptoms, signs and simple investigations may help to do this. The aim of the present study was to assess the causes of fever and identify clinical and laboratory features suggesting serious disease in U.K. children presenting to hospital with temperatures >or=38 degrees C. METHODS: All children with a temperature of >or=38 degrees C seen in two hospitals between August and October 1999. RESULTS: One hundred and forty one children between 8 days and 16 years of age were studied, 64% male, 55% aged under 2 years. Eighty three percent had temperatures between 38 and 39 degrees C. Ninety six percent were casualty or GP referrals and 4% were tertiary referrals. Twenty nine percent (41/141) had serious disease but microbiologically or radiologically proven in only 22% (31/141); pneumonia (nine), meningitis (seven), sepsis (five), urinary tract infection (five), brain abscess (two), toxic shock syndrome (one), appendicitis (one), ischiorectal abscess (one). Forty two percent (5/12) of microbiologically proven meningitis and sepsis and 36% (8/22) of all meningitis and sepsis were meningococcal. Seventy one percent had non-serious diseases. In cases of serious disease the temperature was >39 degrees C in 15% (sensitivity: 14%, specificity: 82%, PPV: 25%). Poor feeding and restlessness predicted serious disease with a sensitivity of 78% and 76%, respectively. Full blood count (FBC) was taken in 50% of patients on admission; in 44% of serious and 24% of non-serious diseases WBC was between 5000 and 15,000/mm(3) and WBC >or=15,000/mm(3) was seen in 39% of serious diseases (sensitivity:10%, specificity: 95%, PPV: 44%). CONCLUSIONS: One out of three of children referred with fever had a serious disease. Degree of temperature and WBC count were poor predictors of serious disease. Interestingly, poor feeding and restlessness were more sensitive predictors, suggesting high fever and WBC count can not replace clinical assessment of the child with a temperature.

Transcranial magnetic-stimulation mapping of the cortical topography of the human masseter muscle.

The cortical topography of several limb and trunk muscles has been disclosed using transcranial magnetic stimulation, but the corticomotor representation of the human jaw muscles has not yet been described. An experimental paradigm incorporating transcranial magnetic stimulation of verified sites on the scalp was used (a) to determine the cortical topography of the human masseter muscle and (b) to assess the reproducibility of the motor map, in seven healthy individuals. The results showed that the masseter was discretely represently on the motor and premotor cortex with interindividual variation in map area, volume and height (p < 0.05). Coefficients of variation and reliability were low (15-18%) and high (89-96%), respectively, for motor maps obtained at experimental sessions 2 weeks apart, indicating high reproducibility. The findings have clinical relevance in the management of patients with cerebral injury involving corticobulbar projections to the masseter.

Effect of motor tasks on the cortical topography of the human masseter muscle.

Non-invasive magnetic stimulation of the brain was earlier used to reveal the corticomotor representation of the human masseter muscle but it is unclear how motor tasks affect this map. An experimental approach incorporating transcranial magnetic stimulation of verified locations on the scalp, surface electromyography, and controlled muscle facilitation was used to disclose the corticomotor output map of the masseter during three isometric tooth-contact tasks, viz., tooth clenching in the intercuspal position, biting on the left molar teeth, and biting on the incisors. Map area was significantly different for all tasks, and map height and volume were also different for biting on the incisor teeth (p<0.05). There was evidence of task-related modulation of corticobulbar activity that appeared to be mainly of corticomotoneuronal origin, although the role of differential, task-associated peripheral afferent input from orofacial receptors could not be discounted.

Improved reproducibility of magnetic stimulation-evoked motor potentials in the human masseter by a new method for locating stimulation sites on the scalp.

In magnetic-stimulation studies where motor-evoked potentials (MEP) are measured on different occasions, accurate relocation of the stimulation site on the scalp is essential. Here a novel method of locating neural stimulation sites was tested and the reproducibility of MEPs in the human masseter assessed. The heads of the participants were immobilized in a plastic mask that incorporated a grid overlying the left cerebral hemisphere. A figure-of-eight coil was oriented with a micromanipulator. Electrodes were placed over the right masseter using a standardized method. Two discrete sites on the grid were stimulated alternately at threshold + 10% whilst participants clenched their teeth. Recordings were repeated after the mask and electrodes had been removed and replaced. Within individual participants, the latency and amplitude of the MEP were reproducible between trials and when the mask and electrodes were replaced. The new method appears to be accurate and practical when recording longitudinal MEP data in the masseter.

Pressure-pain threshold in the human tongue.

AIMS: A new pressure algometer was used to quantify the pressure-pain threshold (PPT) in the human tongue. METHODS: A custom-made device controlled by software and a personal computer was used to measure the PPT in the anterior part of the tongues of 14 young, healthy subjects. The PPT was measured at 3 different rates of pressure application on 3 occasions, 1 week apart. Data were evaluated with analysis of covariance and intraclass correlations. RESULTS: The prototype device had linear output characteristics within the operational range. The mean PPT ranged from 18 to 44 g. The PPT appeared to increase approximately linearly with increasing rate of pressure application (P < 0.001). There were no significant differences in the PPT on different experimental occasions. In individual subjects, the PPT was reliable and uniform. There were significant inter-subject differences in the PPT (P < 0.001). CONCLUSION: The PPT can be measured consistently in the anterior part of the tongue, provided the pressure rate is controlled. The new-pressure algometer appears to have potential clinical utility for quantifying sensation in the human tongue.

A comparison of the validity of generic- and disease-specific measures in the assessment of oral health-related quality of life.

UNLABELLED: In recent years, a number of instruments have been developed to measure the outcomes of oral disease. The Oral Health Impact Profile (OHIP) is the most sophisticated and comprehensive measure developed to date. At present, reports of the use of this measure are confined to descriptive population studies. OBJECTIVES: The aim of this study was to compare the validity of the OHIP with a generic health-related quality of life measure, the SF36. METHODS: Study subjects were in three groups, namely, edentulous patients seeking dental implants ("implant subjects", n = 32), edentulous patients seeking conventional dentures ("edentulous control", n = 35) and dentate patients ("dentate control", n = 21). All subjects completed an OHIP and SF36 prior to receiving any treatment. The edentulous subjects also completed a subjective assessment of satisfaction with their existing conventional dentures. OHIP data were computed using the simple count and weighted scores methods. RESULTS: The median number of negative impacts reported for each group was: 17 (implant subjects), six (conventional control) and one (dentate control). OHIP sub-scale scores were significantly higher (P < 0.001) for implant subjects than control subjects. There were no significant differences between the SF36 sub-scale scores. There was a significant correlation (P < or = 0.01) between aspects of satisfaction with conventional dentures worn by the edentulous subjects and OHIP sub-scale scores. Correlations between denture satisfaction variables and SF36 scores were not significant. CONCLUSIONS: It was concluded that the OHIP shows good discriminant and construct validity properties. As it is oral specific, it will be of greater use in measuring outcomes of oral disorders than generic measures such as SF36. This finding will be relevant when considering the use of health-related quality of life measures to target resources and measure the outcome of clinical intervention.

Patient expectations of oral implant-retained prostheses in a UK dental hospital.

STATEMENT OF PROBLEM: The loss of the natural dentition leads to severe functional impairment in many edentulous adults. A prosthesis retained and supported by osseointegrated dental implants may provide a satisfactory solution for people who have lost all their natural teeth. However, little information is available as to what patients requesting implants expect of implant-retained prostheses. AIM: The aim of this study was to assess the expectations of a group of edentulous patients requesting implant therapy. METHOD: The study included two groups: (1) a group of edentulous adults who requested implant therapy ('implant group'); and (2) an edentulous control group, of similar age and gender distribution as the implant group, receiving conventional complete dentures. Following a clinical and radiographic examination of the patients, data were collected using validated questionnaires. Both groups made a subjective assessment of current dentures. The implant group also completed a questionnaire which assessed expectations of implant-retained prostheses. RESULTS: Baseline satisfaction with current dentures was low in both groups, with the implant group being significantly less satisfied with comfort and stability of their mandibular dentures. Perceived ability of the implant group to chew hard foods was less than the control group. The implant group's expectations of an implant-retained prosthesis were significantly greater than for a conventional denture. CONCLUSION: Careful assessment of patient expectation of implant therapy is essential to determine appropriate treatment need, and to highlight unrealistic expectations.

The efficacy of Emla and 5% lignocaine gel for anaesthesia of human gingival mucosa.

OBJECTIVE: To compare the analgesic effect of a mixture of 2.5% lignocaine and 2.5% prilocaine (Emla) with that of lignocaine gel alone for minor operations on the gingiva. DESIGN: Randomized double-blind trial. SETTING: Teaching hospital, UK. SUBJECTS: 10 healthy dental students (7 men and 3 women, 20-21 years old). INTERVENTIONS: Construction of a reservoir within a splint on each side of the mouth and insertion of splints. The volunteers acted as their own controls, and the sides used for each anaesthetic were chosen at random. MAIN OUTCOME MEASURES: Measurement of pressure-pain threshold by a standard technique. RESULTS: The median (range) duration of anaesthesia after Emla (22.5, 12-30) was significantly longer than after lignocaine alone (12.5, 0-25) (P=0.01), and the area under the curve for the pressure-pain threshold for Emla (2053, 199-4564) was significantly greater than for lignocaine alone (986, 169-2942) (P=0.01). CONCLUSION: Emla is a more effective topical anaesthetic agent than lignocaine alone. Although its duration of action is relatively short it is adequate for minor operations on the gingiva.

The general L-amino acid permease of Rhizobium leguminosarum is an ABC uptake system that also influences efflux of solutes.

A general L-amino acid permease (Aap) from the ABC transporter family, encoded by four genes (aapJ, Q, M, P), has been cloned and characterized in Rhizobium leguminosarum. It transports a wide range of L-amino acids but has a preference for those with polar side-chains. A single binding protein of broad specificity (AapJ) is required for transport of all solutes. Unusually for an ABC transporter, Aap has both high affinity for and supports high rates of solute uptake. Genes for putative amino acid permeases with broad specificity for amino acids also exist in Escherichia coli and probably in Pseudomonas fluorescens, although the permease from E. coli does not appear to be expressed. Aap is an active uptake system that also affects the efflux of a broad range of amino acids. Efflux can be measured both as the loss of an intracellular amino acid after the addition of an excess of a homologous or heterologous amino acid, and as excretion of intracellularly synthesized glutamate. Mutation of Aap prevented efflux of intracellular amino acids caused by the addition of an extracellular heterologous amino acid, while overexpression increased the rates of such efflux. Furthermore, excretion of glutamate synthesized inside the cell was reduced by 76% in an aap strain. All four gene products, including the binding protein (AapJ), appear to be needed for efflux. Aap from R. leguminosarum expressed in E. coli also promoted efflux on addition of an extracellular heterologous amino acid. These results indicate either that Aap regulates an efflux channel/transporter or that solute has access to the translocation pathway of Aap from both sides of the membrane.

Aspartate transport by the Dct system in Rhizobium leguminosarum negatively affects nitrogen-regulated operons.

Amino acid uptake by the general amino acid permease (Aap) of Rhizobium leguminosarum strain 3841 was severely reduced by the presence of aspartate in the growth medium when glucose was the carbon source. The reduction in transport by the Aap appeared to be caused by inhibition of uptake and not by transcriptional repression. However, as measured with lacZ fusions, the Ntr-regulated gene glnII was repressed by aspartate. The negative regulatory effect on both the Aap and glnII was prevented by mutation of any component of the dicarboxylate transport (Dct) system or by the inclusion of a C4- dicarboxylate in the growth medium, including the non-metabolizable analogue 2-methylsuccinate. As measured by total uptake and with a dctA-lacZ fusion, aspartate was an efficient inducer of the Dct system, but slightly less so than succinate alone or succinate and aspartate together. Thus, aspartate does not cause overexpression of DctA leading to improper regulation of other operons. Transport measurements revealed that the Dct system has an apparent Km for succinate of 5 microM and an apparent Ki for aspartate inhibition of succinate uptake of 5 mM. These data imply that the Dct-mediated accumulation of aspartate causes an unregulated build-up of aspartate or a metabolic product of it in the cell. This accumulation of aspartate is prevented either by mutation of the dct system or by the presence of a higher affinity substrate that will reduce access of aspartate to the carrier protein. Elevation or disruption of the intracellular aspartate pool is predicted to disrupt N-regulated operons and nitrogen fixation.

A patient-based assessment of implant-stabilized and conventional complete dentures.

STATEMENT OF PROBLEM: Outcomes of oral implant therapy have been described primarily in terms of implant survival rates and the durability of implant superstructures. Reports of patient-based outcomes of implant therapy have been sparse, and none of these studies have used oral-specific health status measures. PURPOSE: This study assessed the impact of implant-stabilized prostheses on the health status of complete denture wearers using patient-based, oral-specific health status measures. It also assessed the influence of preoperative expectations on outcome. MATERIAL AND METHODS: Three experimental groups requesting replacement of their conventional complete dentures completed an Oral Health Impact Profile (OHIP) and a validated denture satisfaction scale before treatment. One group received an implant-stabilized prosthesis (IG), and 2 groups received new conventional complete dentures (CDG1 and CDG2). After treatment, all subjects completed the health status measures again; preoperative data were compared with postoperative data. RESULTS: Before treatment, satisfaction with complete dentures was low in all 3 groups. Subjects requesting implants (IG and CDG1) had high expectations for implant-stabilized prostheses. Improvement in denture satisfaction and OHIP scores was reported by all 3 groups after treatment. Subjects who received their preferred treatment (IG and CDG2 subjects) reported a much greater improvement than CDG1 subjects. Preoperative expectation levels did not appear to influence satisfaction with the outcomes of implant therapy in IG subjects. CONCLUSION: Subjects who received implants (IG) that replaced conventional complete dentures reported significant improvement after treatment, as did subjects who requested conventional replacement dentures (CDG2). The OHIP appears useful in identifying patients likely to benefit from implant-stabilized prostheses.

Response of psoriasis to sunbed treatment: comparison of conventional ultraviolet A lamps with new higher ultraviolet B-emitting lamps.

BACKGROUND: Sunbeds fitted with conventional ultraviolet (UV) A lamps that have about 0.7% UVB emission are widely used by patients with psoriasis even though they are minimally effective. A new fluorescent sunbed lamp has been developed that emits a higher proportion of UVB (4.6%) than conventional lamps and also requires shorter exposure times to achieve equivalent erythema. OBJECTIVES: To perform a randomized, within-patient comparison of conventional sunbed lamps (Cleo Performance) with the new lamps (Cleo Natural) in the treatment of psoriasis. METHODS: A sunbed and canopy unit were modified to allow exposure to Cleo Performance lamps on one side of the body (front and back) and Cleo Natural lamps to the other side of the body. Two studies were done. In study 1, equal erythemal doses were given from the two lamp types. In study 2, equal exposure times were given. We treated 34 patients with psoriasis, giving 12 exposures over a period of 4 weeks. Assessment was made using a modified Psoriasis Area and Severity Index (PASI) score, individual plaque assessment and patient questionnaire. RESULTS: Fourteen patients completed each study. In study 1, there was no significant difference in median improvement in half-body PASI score for the two lamp types. In study 2, there was a significant difference in PASI score improvement between the two lamps (median Cleo Performance change minus median Cleo Natural change was - 2.20; 95% confidence interval - 3.75 to - 0.65; P = 0.006). CONCLUSIONS: That no difference in response was found when equal erythemal doses were given suggests that the spectral emission of the Cleo Natural lamp is of no greater advantage for clearance of psoriasis than conventional lamps. However, the Cleo Natural lamps are more erythemally powerful, and exposure times similar to those used in conventional sunbeds result in a significant improvement of psoriasis. The risk of non-melanoma skin cancer from different patterns of exposure to Cleo Natural lamps can be estimated using established numerical models.

Snoring, daytime sleepiness and stroke: a case-control study of first-ever stroke.

Previous reports have shown an association between snoring and stroke but it is not clear whether this reflects confounding factors nor whether the association is attributable to obstructive sleep apnoea (OSA). We performed a case-control study of 181 patients admitted to hospital with first-ever stroke and community control subjects matched individually for age, sex and general practitioner. Subjects were interviewed with a structured questionnaire to identify snoring, daytime sleepiness and stroke risk factors. The association between snoring alone and stroke was not statistically significant: odds ratio (95% CI) 1.44 (0.88, 2.41). Daytime sleepiness was, however, significantly associated with stroke: odds ratio 3.07 (1.65, 6.08). Multiple logistic regression showed that hypertension, current smoking, taking alcohol regularly (negatively) and a higher Epworth sleepiness score were independently associated with stroke. The results suggest that the previously reported association between 'simple' snoring and stroke might have been due to poor controlling for confounding variables. Our study suggests an association with greater sleepiness prestroke, the cause of which is unclear, although OSA is a possible candidate.