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R Yates

Publications and source records attributed to R Yates.

At least 19 recordsLinked to original sources
PubMed2005

A comparison of a reformulated potassium citrate desensitising toothpaste with the original proprietary product.

OBJECTIVES: The recent tendency for toothpaste manufacturers to combine active ingredients for benefits to a number of oral problems requires that such combinations do not vitiate the action of any one agent. The aim of this study was to compare the desensitising effects of a modified formulation with the established product. MATERIALS AND METHODS: The study was a randomised, double blind, two treatment parallel design comparing an existing potassium citrate toothpaste product (Positive Control) with the same formulation to which triclosan and zinc citrate had been added (Test). A total of 56 subjects with dentine hypersensitivity (DH) completed the 8 week study period. At baseline, days 14 and 56 visual analogue scale scores were recorded by the subjects in response to air evaporative and cold water stimuli. RESULTS: Both groups showed improvements, mostly statistically significant, from baseline to day 14 and through to day 56. Most data favoured the Test paste but differences were, for the most part, not significant. CONCLUSIONS: It is concluded that the addition of known anti-plaque agents to an established potassium salt based desensitising toothpaste did not adversely affect the activity of the product in the treatment of DH.

Anti-Infective Agents, Local↗
PubMed2005

Improving response rates to primary and supplementary questionnaires by changing response and instruction burden: cluster randomised trial.

OBJECTIVE: Supplementary questionnaires provide additional information from subgroups, but may have an attritional effect on response rates. We examined the effects of different instruction methods on response rates to a two-part questionnaire. METHODS: The ACT Kindergarten Health Survey comprises a health questionnaire for all school-entry children. A supplementary questionnaire targets children with respiratory symptoms. We cluster-randomised 109 schools in the ACT (4,494 children) to two instruction groups. Group 1 (instruction burden) had instructions to complete the supplementary questionnaire if certain questions in the primary questionnaire were answered. Group 2 (response burden) had instructions to complete both questionnaires irrespective of answers to the primary questionnaire. RESULTS: Instructing all respondents to complete both questionnaires regardless of eligibility resulted in a statistically significantly lower primary questionnaire response rate (82% vs. 87%), but a statistically significantly higher response rate to the supplementary questionnaire (99% vs. 91%). The net effect was a small overall gain (82% vs. 79%) for the response burden group. CONCLUSION: Increasing the response burden had a minor impact on response rate to the primary questionnaire, but increased the response rate for most items to the supplementary questionnaire. IMPLICATIONS: Large surveys may be broken into primary and supplementary questionnaires, if strategies to maximise response rates are used. Questionnaires may need to be modified to take into account the likely attrition on response to either questionnaire resulting from instruction and response burdens.

Child↗
PubMed2005

Distribution of intranasal C-zolmitriptan assessed by positron emission tomography.

Nine healthy volunteers aged 18-28 years were recruited into this open, single-centre, two-phase trial. In phase 1, two volunteers received a single dose of 11C-zolmitriptan 2.5 mg administered as a nasal spray and then underwent positron emission tomography (PET) scanning to determine the most appropriate times for scanning in phase 2. In phase 2, six volunteers received two doses and an additional volunteer one dose of 11C-zolmitriptan 2.5 mg intranasally. Volunteers underwent PET scanning over sectors covering one of the nasopharynx, lungs or abdomen, for up to 1.5 h postdose. The brain was also scanned and plasma zolmitriptan levels were measured. Almost 100% of the administered dose was detected in the nasopharynx immediately after dosing. This declined thereafter to about 50% at 20 min and to 35% at 80 min after dosing. Radioactivity appeared slowly in the upper abdomen, with 25% of given radioactivity detected at 20 min and persisting until 80 min after dosing. Minimal radioactivity was detected in the lungs. Radioactivity was detectable within brain tissue suggesting central penetration of zolmitriptan. Zolmitriptan in plasma had approached its maximum concentration by 15 min postdose. The data indicate initial absorption across the nasal mucosa contributing to an early systemic availability. 11C-Zolmitriptan administered intranasally was well tolerated.

Administration, Inhalation↗
PubMed2004

A methodology using subjective and objective measures to compare plaque inhibition by toothpastes.

OBJECTIVES: Plaque scoring usually employs subjective indices. The aim was to compare plaque inhibition of three toothpastes using two objective and one subjective measures of plaque. MATERIAL AND METHODS: Formulations were: (1) an experimental anti-plaque paste (test); (2) an experimental paste (minus active or negative control); and (3) a proprietary anti-plaque toothpaste product (positive control). The study was a blind, randomised crossover design using a 4-day, no tooth brushing, plaque regrowth model and involving 22 healthy subjects. After baseline plaque removal, subjects rinsed twice a day with slurries of the allocated paste. On day 5, plaque was scored by index, wet weight and optical density of extracted disclosing solution from the plaque (stain intensity). RESULTS: All data showed the same pattern. There were highly significant subject and treatment effects but not period effects. The positive control was highly significantly more effective in plaque control than the test and minus active experimental formulations, which in turn were not significantly different from each other. There were strong and significant correlations between pairs of scoring methods particularly wet weight and stain intensity. CONCLUSION: The use of objective methods of plaque alongside conventional subjective indices provided convincing evidence for increased discriminatory power in a study comparing plaque inhibition by toothpastes.

Adult↗
PubMed2003

Successful early in utero management of fetal hydrothorax in a twin pregnancy.

We present a case of dichorionic diamniotic twin pregnancy in which one of the fetuses was found to have a major pleural effusion at 15 weeks of gestation. A single-needle pleural fluid aspiration was performed at 15 and 16 weeks, but the fluid reaccumulated quickly after each procedure and at 16 weeks, the fetus was found to become progressively hydropic. A shunt was then successfully inserted at 17 weeks, which is the earliest gestation reported so far in the literature for such a procedure to treat isolated hydrothorax. Because we felt that the fetus would be too small for a classical double-pigtail pleuroamniotic shunt, we used a multilength double-pigtail bladder stent (Harrison drain; Cook; Spencer; Indiana; USA) via a 13-gauge echo tip trocar. This shunt could be used for both singleton and twin pregnancies presenting with fetal pleural effusion from as early as 16 to 17 weeks to prevent the development of fetal hydrops and polyhydramnios and subsequent premature delivery. Treatment at this stage of gestation would also minimize the risk of lung hypoplasia, which is the main clinical issue when shunts are inserted after 24 weeks.

Amnion↗
PubMed2002

A method to compare four mouthrinses: time to gingivitis level as the primary outcome variable.

BACKGROUND AND AIM: The experimental gingivitis model is a well-established method in comparing the chemical antiplaque activity of agents and products. The aim of the present study was to use time in order to achieve an exit level of bleeding on probing (BOP) as the primary outcome variable. METHODS: The study was a single blind, randomised four treatment parallel group design employing 76 healthy volunteers. The cohort was accepted into the study proper if they achieved a level of </= 25% BOP after a 5-week pre-study oral hygiene phase. At baseline, 1, 2, 3, 4, 5 weeks BOP, modified gingival index (MGI) and plaque index scores were obtained from each subject. After baseline, oral hygiene was suspended and subjects rinsed twice daily with one of the test rinses, namely: 1 0.05% cetylpyridinium chloride 2 Control fluoride 3 0.2% chlorhexidine 4 0.3% triclosan Subjects were removed from the study when they achieved >/= 50% BOP. Using the baseline and exit BOP, MGI and plaque, a deterioration rate for each parameter was derived and used as the unit of analysis. RESULTS: There were highly significant treatment differences for all three parameters. Paired analyses revealed chlorhexidine was highly significantly more effective than the other rinses for all three parameters. CPC and triclosan were not different from the control for BOP, but CPC was significantly different from the control for MGI and plaque, and triclosan was different from the control for plaque. There were no differences between the CPC and triclosan rinses. CONCLUSIONS: The method achieved the expected result of differentiating between the chlorhexidine and the other rinses. Some modification of the method, primarily to group sizes, should improve specificity. The method has the considerable volunteer appeal of early exit, particularly when allocated to control or low activity treatments for plaque.

Adult↗
PubMed2002

Dynamic three-dimensional color Doppler ultrasound of human fetal intracardiac flow.

OBJECTIVES: To develop dynamic three-dimensional ultrasound techniques for prenatal imaging of the intracardiovascular flow as well as the cardiovascular structure to address difficulties in assessing the spatially complex hemodynamics and morphology of the fetal heart. METHODS: Gray-scale and color (velocity) Doppler echocardiography were performed on 12 fetuses to provide serial anatomical and rheological tomograms which were spatially registered in three dimensions. Using a second ultrasound machine simultaneously, spectral Doppler ultrasound was performed to record umbilical arterial waveforms, thus providing the temporal (fourth) dimension in terms of the cardiac cycle and facilitating removal of motion artifacts. RESULTS: Acquisitions were successful in eight of 15 attempts. Imaging of the flow of blood in four dimensions was achieved in six of the eight datasets. In one case with complex cardiac malformations, three-dimensional reconstructions at systole and diastole offered dynamic diagnostic views not appreciated on the cross-sectional images. CONCLUSIONS: Our novel technique has made possible the prenatal visualization of the spatial distribution and true direction of intracardiac flow of blood in four dimensions in the absence of motion artifacts. The technique suggests that diagnosis of cardiac malformations can be made on the basis of morphological and hemodynamic changes throughout the entire cardiac cycle, offering unique and significant information complementary to conventional techniques. Further work to integrate the several non-purpose-built machines into a single system will improve the rate of acquisition of data, and may provide a new means of imaging and modeling structure and hemodynamics, not only for the fetal heart but for many other moving body parts.

Coronary Circulation↗
PubMed2001

Rapid and radical amniodrainage in the treatment of severe twin-twin transfusion syndrome.

We have evaluated the role of a rapid and radical method of amniodrainage in the treatment of severe twin-twin transfusion. The outcome of 15 patients with severe twin-twin transfusion for which a amniodrainage was performed by means of a vacuum bottle system was compared with the outcome of 15 patients with a similar condition, matched for gestational age at the time of the initial procedure and drained using a standard procedure. In the study group the amniodrainage ended when no amniotic fluid could be aspirated, whereas the women in the standard group were drained with a syringe system and the fluid was removed until the deepest amniotic fluid pool was <8 cm. At the initial procedure, the mean volume of amniotic fluid drained was significantly (p<0.05) higher (3252 vs 2153 ml) and the length of the procedure significantly (p<0.001) shorter (21 vs 41 min) in the study group than in the standard group. The mean post-procedure amniotic fluid index was significantly (p<0.001) smaller (2.9 vs 7.7 cm) after radical amniodrainage than after the standard amniodrainage. The mean number of procedures was significantly (p<0.001) lower (1.5 vs 5.6) in the study group compared to the standard group. In the study group the mean placental thickness increased significantly (p<0.001) from 9 mm before the procedure to 49 mm after, and the overall perinatal survival rate was 80% and the proportion of pregnancies with at least one survivor was 93%. The present data indicate that early, rapid and radical amniodrainage is an effective and low-cost therapy for severe twin-twin transfusion syndrome. Compared to the standard amniodrainage technique it also appears to reduce the need for multiple procedures.

Amnion↗
PubMed2001

An early bone tool industry from the Middle Stone Age at Blombos Cave, South Africa: implications for the origins of modern human behaviour, symbolism and language.

Twenty-eight bone tools were recovered in situ from ca. 70 ka year old Middle Stone Age levels at Blombos Cave between 1992 and 2000. These tools are securely provenienced and are the largest collection to come from a single African Middle Stone Age site. Detailed analyses show that tool production methods follow a sequence of deliberate technical choices starting with blank production, the use of various shaping methods and the final finishing of the artefact to produce "awls" and "projectile points". Tool production processes in the Middle Stone Age at Blombos Cave conform to generally accepted descriptions of "formal" techniques of bone tool manufacture. Comparisons with similar bone tools from the Later Stone Age at Blombos Cave, other Cape sites and ethnographic collections show that although shaping methods are different, the planning and execution of bone tool manufacture in the Middle Stone Age is consistent with that in the late Holocene. The bone tool collection from Blombos Cave is remarkable because bone tools are rarely found in African Middle or Later Stone Age sites before ca. 25 ka. Scarcity of early bone tools is cited as one strand of evidence supporting models for nonmodern behaviour linked to a lack of modern technological or cognitive capacity before ca. 50 ka. Bone artefacts are a regular feature in European sites after ca. 40 ka, are closely associated with the arrival of anatomically modern humans and are a key behavioural marker of the Upper Palaeolithic "symbolic explosion" linked to the evolution of modern behaviour. Taken together with recent finds from Klasies River, Katanda and other African Middle Stone Age sites the Blombos Cave evidence for formal bone working, deliberate engraving on ochre, production of finely made bifacial points and sophisticated subsistence strategies is turning the tide in favour of models positing behavioural modernity in Africa at a time far earlier than previously accepted.

Anthropology, Physical↗
PubMed2001

Online motion-gated dynamic three-dimensional echocardiography in the fetus--preliminary results.

The aim of this study was to visualise the fetal heart in dynamic three dimensions (4-D) during an ultrasound (US) scan (online), rather than after (offline). With special pairing and sequential setting to minimise interference between two scanners, umbilical arterial Doppler waveforms (UADWs) from one scanner were used as an online motion gating source to trigger simultaneous 3-D cardiac structural data acquisition by another. Of 25 data sets from 10 fetuses, 18 were acquired in 15 to 30 s per set with > or = 50% Doppler waveforms efficiently converted to triggering signals. Of 15 valid 4-D data sets, 10 were reconstructed in 2 to 20 min, compared to over 2 h previously reported (mainly for offline gating). Fine structures (including chordae tendinae and trabecular muscles) were depicted in six sets. The main problems in degrading 4-D images were extensive shadowing (6) from bony structures during rigid mechanical scanning, and random motion artefacts (6) from prolonged setting-up time with a complex combination of several systems. Integration of these systems is, therefore, recommended.

Artifacts↗
PubMed2001

The erosive effects of some mouthrinses on enamel. A study in situ.

BACKGROUND: There are both anecdotal clinical and laboratory experimental data suggesting that low pH mouthrinses cause dental erosion. This evidence is particularly relevant to acidified sodium chlorite (ASC) formulations since they have plaque inhibitory properties comparable to chlorhexidine but without the well known local side effects. AIM: Studies in situ and in vitro were planned to measure enamel erosion by low pH mouthrinses. The study in situ measured enamel erosion by ASC, essential oil and hexetidine mouthrinses over 15-day study periods. The study was a 5 treatment, single blind cross over design involving 15 healthy subjects using orange juice, as a drink, and water, as a rinse, as positive and negative controls respectively. 2 enamel specimens from unerupted human third molar teeth were placed in the palatal area of upper removable acrylic appliances which were worn from 9 a.m. to 5 p.m., Monday to Friday for 3 weeks. Rinses were used 2x daily and 250 ml volumes of orange juice were imbibed 4x daily. Enamel loss was determined by profilometry on days 5, 10 and 15. The study in vitro involved immersing specimens in the 4 test solutions together with a reduced acid ASC formulation for a period of 4 h under constant stirring; Enamel loss was measured by profilometry every hour. RESULTS: Enamel loss was in situ progressive over time with the 3 rinses and orange juice but negligible with water. ASC produced similar erosion to orange juice and significantly more than the two proprietary rinses and water. The essential oil and hexetidine rinses produced similar erosion and significantly more than water. Enamel loss in vitro was progressive over time, and the order from low to high erosion was reduced acid ASC, ASC, Essential oil, and hexetidine mouthrinses and orange juice. CONCLUSION: Based on the study in situ, it is recommended that low pH mouthrinses should not be considered for long term or continuous use and never as pre-brushing rinses. In view of the plaque inhibitory efficacy of ASC, short- to medium-term applications similar to those of chlorhexidine would be envisaged.

Adult↗
PubMed2001

Pharmacokinetics and tolerability of the orally active selective epidermal growth factor receptor tyrosine kinase inhibitor ZD1839 in healthy volunteers.

OBJECTIVE: To investigate the pharmacokinetics and tolerability of ZD1839 (Iressa), an orally active selective epidermal growth factor receptor-tyrosine kinase inhibitor, in healthy volunteers. DESIGN: Two randomised, double-blind, placebo-controlled, parallel-group studies of pharmacokinetics and tolerability, followed by a nonblind, randomised, 2-period crossover study to assess the effect of food on bioavailability. SETTING: Two centres in the UK. STUDY PARTICIPANTS: Healthy male volunteers aged between 18 and 62 years. INTERVENTIONS: The first study investigated the pharmacokinetics and tolerability of ascending single oral doses of ZD1839 (1 to 75mg). The second study investigated the pharmacokinetics and tolerability of multiple doses of ZD1839 (100mg once daily for 3 days). The third study investigated the effect of food on the bioavailability of a single 50mg dose of ZD1839. OUTCOME MEASURES AND RESULTS: Peak plasma drug concentrations (Cmax) of ZD 1839 occurred between 3 and 7 hours after administration. Cmax and area under the concentration-time curve (AUC) were dose-proportional from 10 to 100mg. The terminal elimination half-life (t1/2beta) was 28 hours (range 12 to 51 hours). Cmax was reduced by 34% and AUC by 14% by ingestion of food; t1/2beta was not affected. Urinary recovery of ZD1839 was <0.5%, indicating that this was not a major route of elimination. The pharmacokinetics of ZD1839 during administration of multiple doses could be predicted from day 1 values. There were no serious adverse events or withdrawals, and the frequency of adverse events was similar that with placebo. CONCLUSIONS: These data support the further clinical investigation of ZD 1839. The elimination half-life suggests that once daily oral administration is appropriate.

Adolescent↗
PubMed2000

Scientific, ethical, and logistical considerations in introducing a new operation: a retrospective cohort study from paediatric cardiac surgery.

OBJECTIVE: To review the initial impact on mortality of infants with congenital heart disease of a new surgical technique that is now taken for granted. DESIGN: Retrospective cohort study. SETTING: A tertiary paediatric cardiology centre. SUBJECTS: 325 consecutive neonates with simple transposition of the great arteries admitted before, during, and after the preferred management changed from the Senning operation to the arterial switch (1978-98); and 100 consecutive neonates requiring a different neonatal open heart operation that did not change in that period. MAIN OUTCOME MEASURES: Mortality before and early after operation reconstructed sequentially as the series evolved and retrospectively once the series was complete; actuarial survival associated with the different treatment strategies. RESULTS: For both the transposition and the comparison group, early mortality in 1998 was lower than in 1978. During that period, however, there was a phase temporally related to the adoption of the switch operation in which early mortality for transposition increased. Actuarial survival of recent patients with "intention to treat" with arterial switch is superior to those with intention to treat with the Senning operation, as predicted when the switch operation was first adopted. CONCLUSIONS: A period of increased hazard for individual patients may occur when a specialist community, a particular unit, and an individual surgeon are all learning a new technique concurrently. Obtaining informed consent during this time of uncertainty is helped by clarity about the objectives of treatment and availability of relevant local and international data.

Child↗
PubMed2000

Transposition of the great arteries, ventricular septal defect and diaphragmatic hernia in a fetus: the role of prenatal diagnosis in helping to predict postnatal survival.

Congenital heart disease and congenital diaphragmatic hernia are frequently associated. The combination of these lesions is predictive of poor postnatal survival. The identification of both lesions during prenatal life may facilitate improved survival in carefully selected cases. We present a case of left-sided diaphragmatic hernia with transposition of the great arteries and a ventricular septal defect (VSD) that survived following repair of both defects within the first six weeks of life.

Adult↗
PubMed2000

Effects of the aromatase inhibitor anastrozole on serum oestrogens in Japanese and Caucasian women.

PURPOSE: Substantial differences in plasma oestrogen disposition have been reported between Japanese and Caucasian women, but there are currently few data available on the relative endocrinological effects of aromatase inhibitors in these two groups. Hence, the effects of the nonsteroidal aromatase inhibitor anastrozole on serum oestrogen concentrations were compared in 24 healthy postmenopausal Japanese women and 24 healthy postmenopausal Caucasian women. METHODS: Anastrozole, 1 mg/day, was given once daily for 16 days. Serum oestradiol and oestrone sulphate levels were measured on three consecutive days beginning 2 days before the first dose, and on a further three consecutive days beginning on the penultimate day of dosing. Trough concentrations of anastrozole (measured 24 h after dosing) were also determined during the same periods. RESULTS: There were no substantial differences in plasma oestrogen concentrations between the Japanese and Caucasian women at baseline. On average, anastrozole suppressed serum oestradiol and oestrone sulphate levels by approximately 87% and 93%, respectively, for both Japanese and Caucasian women, and minimum plasma anastrozole concentrations at steady-state (anastrozole C(min)) were also similar in both groups. Statistical analysis of serum oestradiol and serum oestrone sulphate levels, and plasma anastrozole C(min) showed that there were no statistically significant differences between the Japanese and Caucasian women. CONCLUSION: Neither the pharmacodynamic effects of anastrozole on serum oestrogens nor the pharmacokinetics of anastrozole differ between postmenopausal Japanese and Caucasian women. Hence, these findings suggest that the therapeutic benefits of anastrozole in Caucasians will be predictive of the drug's effect in Japanese women and support the use of anastrozole in postmenopausal Japanese women with breast cancer.

Aged↗