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Biomedical subjects

D Roberts

Publications and source records attributed to D Roberts.

At least 109 records · Page 6Linked to original sources
PubMed1998

Controlled trial of hypnotherapy for weight loss in patients with obstructive sleep apnoea.

OBJECTIVE: To assess if hypnotherapy assists attempts at weight loss. DESIGN: Randomised, controlled, parallel study of two forms of hypnotherapy (directed at stress reduction or energy intake reduction), vs dietary advice alone in 60 obese patients with obstructive sleep apnoea on nasal continuous positive airway pressure treatment. SETTING: National Health Service hospital in the UK. MEASURES: Weight lost at 1, 3, 6, 9, 12, 15 and 18 months after dietary advice and hypnotherapy, as a percentage of original body weight. RESULTS: All three groups lost 2-3% of their body weight at three months. At 18 months only the hypnotherapy group (with stress reduction) still showed a significant (P < 0.02), but small (3.8 kg), mean weight loss compared to baseline. Analysed over the whole time period the hypnotherapy group with stress reduction achieved significantly more weight loss than the other two treatment arms (P < 0.003), which were not significantly different from each other. CONCLUSIONS: This controlled trial on the use of hypnotherapy, as an adjunct to dietary advice in producing weight loss, has produced a statistically significant result in favour of hypnotherapy. However, the benefits were small and clinically insignificant. More intensive hypnotherapy might of course have been more successful, and perhaps the results of the trial are sufficiently encouraging to pursue this approach further.

Cohort Studies↗
PubMed1998

Investigating relationships between a range of potential indicators of general practice prescribing: an observational study.

OBJECTIVES: (i) to describe the variation in a number of potential prescribing indicators across a large number of general practices, (ii) to determine whether particular indicators are associated with higher or lower overall prescribing costs, (iii) to determine how particular indicators are correlated with each other, (iv) to determine whether the indicators are stable over time. DESIGN: Observational study based on the analysis of PACT (Prescribing Analysis and Cost) data for general practices. SETTING: The Trent region of England. SUBJECTS: 809 general practices. MAIN OUTCOME MEASURES: Variations in a range of potential prescribing performance indicators; correlations between these indicators and NIC (net ingredient costs) per ASTRO-PU (Age, sex and temporary resident originated prescribing unit); change in indicators between the financial year 1994-5 and 1995-6. RESULTS: Wide variations were found between practices in a range of potential prescribing performance indicators. There were positive correlation (P < 0.001) between NIC per ASTRO-PU and indicators of relatively high cost prescribing within different therapeutic areas. There were negative correlations (P < 0.001) with indicators of relatively low cost prescribing. There were positive intercorrelations (P < 0.001) between indicators of relatively high cost prescribing. For most indicators there were significant changes (P < 0.001) in values between the two years. CONCLUSION: There are considerable variations between general practices in prescribing performance indicators and the indicators show changes over time. We have demonstrated correlations between different indicators that lend support to the idea that such indicators might act as proxies for more general prescribing patterns. However, most of the correlations we observed were not strong. Further research is needed into the development and use of indicators based on PACT data.

Drug Prescriptions↗
PubMed1998

Overcrowding of Culex sitiens (Diptera: Culicidae) larvae: population regulation by chemical factors or mechanical interference.

Crowding of Culex sitiens Wiedemann larvae was investigated to determine whether pupation was delayed by the presence of chemical factors in the water or by mechanical interference. As the larval density increased from 0.05 to 1.0 larvae per milliliter of water, the duration of larval development increased from 7.5 to 23.0 d and larvae mortality increased from 1.7 to 99.6%. At high larval densities (2 larvae per milliliter), the larvae did not pupate, but remained alive as 4th instars for at least 50 d, even after their abundance subsequently declined due to mortality. When not crowded, 80% of the larvae fed at the surface; the remainder fed mainly on the bottom (even at a depth of 35 cm). Removal of chemical retardants by changing the water daily increased pupation to 65% (compared with 4% in controls, in which the water was not changed), but this was less than the effect of reducing mechanical interference by increasing the surface area, which increased pupation to 98%. Therefore, the main density-dependent factor was mechanical interference during feeding, but prolonged development to 19 d showed that chemical retardants also were important. The chemical retardant was not stable, so that 2nd generation larvae reared in the same water were unaffected, but its effect was irreversible, because most crowded larvae moved to clean water and a lower density did not pupate.

Animals↗
PubMed1998

Modeling of airflow in the pharynx with application to sleep apnea.

A three-dimensional numerical modeling of airflow in the human pharynx using an anatomically accurate model was conducted. The pharynx walls were assumed to be passive and rigid. The results showed that the pressure drop in the pharynx lies in the range 200-500 Pa. The onset of turbulence was found to increase the pressure drop by 40 percent. A wide range of pharynx geometries covering three sleep apnea treatment therapies (CPAP, mandibular repositioning devices, and surgery) were modeled and the resulting flow characteristics were investigated and compared. The results confirmed that the airflow in the pharynx lies in the laminar-to-turbulence transitional flow regime and thus, a subtle change in the morphology caused by these treatment therapies can significantly affect the airflow characteristics.

Humans↗
PubMed1998

Ambient pH is a major determinant in the expression of cuticle-degrading enzymes and hydrophobin by Metarhizium anisopliae.

Secretion of proteolytic and chitinolytic enzymes is a hallmark of infection processes of Metralhizium anisopliae in response to host (insect) cuticular signals. The regulation of these enzymes (subtilisin-like proteases [Pr1a and Pr1b], trypsin-like proteases [Pr2], metalloproteases, aspartyl proteases, aminopeptidase, and chitinases) and a hydrophobin was investigated by Northern analysis and/or enzyme assay. The production of each enzyme showed a differential expression pattern in response to ambient pH; enzymes were synthesized only at pHs at which they function effectively, irrespective of whether the medium contained an inductive cuticle substrate. Three aspartyl proteases (pH optimum, 3), and chitinase (pH optimum, 5) showed maximal accumulation at acidic pHs. The highest level of aminopeptidase (pH optimum, 7) was detected at pH 7. The highest levels of five metalloproteases (pH optima, ca. 7) were detected over the pH range 6 to 8. Two trypsins and several subtilisin-like Pr1 isoforms with pH optima of ca. 8 were produced only under alkaline conditions. Northern analysis of RNA species corresponding to seven cDNA sequences encoding proteases and chitinase confirmed that the ambient pH played a major role in gene expression of secreted proteins. Hydrophobin was expressed almost equally at pHs 5 and 8 but was not expressed at pH 3. During fungal penetration, the pH of infected cuticle rises from about 6.3 to 7.7. Consistent with pH regulation of enzyme production, serine and metalloproteases were produced in situ during infection, but no production of aspartyl proteases was found. We propose that the alkalinity of infected cuticle represents a physiological signal that triggers the production of virulence factors.

Chitinases↗
PubMed1998

Evaluation of technician supervised treadmill exercise testing in a cardiac chest pain clinic.

OBJECTIVE: To determine the efficacy and safety of trained cardiac technicians independently performing treadmill exercise stress tests as part of the assessment of patients with suspected angina pectoris. DESIGN: Retrospective comparison of 250 exercise tests performed by cardiac technicians and 225 tests performed by experienced cardiology clinical assistants (general practitioners who perform regular NHS cardiology duties), and consultant cardiologists over the same time period. SETTING: Regional cardiac centre with a dedicated cardiac chest pain clinic. PATIENTS: All patients were referred by their general practitioners with a history of recent onset of chest pain, which was suspected to be angina pectoris. OUTCOME MEASURES: Peak workload achieved, symptoms, indications for termination, complications. RESULTS: The diagnostic yield of technician supervised tests (percentage positive or negative) was similar to that of medically supervised tests (76% v 69%, NS). The average peak workload achieved by patients was less by 1.2 mets (p < 0.005). This was probably due to more tests being terminated earlier due to chest pain and ST segment depression in the technician group compared with doctors (10% and 16% v 5% and 11% respectively, p = 0.06 and 0.07). One patient in the technician supervised group developed a supraventricular tachycardia during the recovery phase of the exercise test. CONCLUSIONS: Technician supervised stress testing is associated with a high diagnostic rate and low complication rate in patients with suspected ischaemic heart disease. Its efficacy is comparable to tests supervised by experienced doctors and its use should be encouraged.

Aged↗
PubMed1998

Longitudinal study of bone turnover after acute spinal cord injury.

Increased bone turnover is a sequel of spinal cord injury (SCI) and predisposes to a number of clinically relevant complications, including osteoporosis and fractures. There are limited data available regarding the changes in modern markers of bone metabolism after SCI. We report a 6-month longitudinal follow-up of biochemical markers of bone metabolism (free and total deoxypyridinoline, total pyridinoline, N-telopeptide, osteocalcin, and total alkaline phosphatase) and bone mineral densitometry in 30 subjects with acute SCI. Markers of bone formation showed only a minor rise, remaining within the reference range. In contrast, markers of bone resorption showed a significant rise after acute SCI, peaking around weeks 10-16, with values up to 10 times the upper limit of normal. Paired bone mineral densities (n = 11; on the average, determined 14 weeks apart) showed no change at the hip, lumbar spine, or radius, but demonstrated a decrement in the entire lower limbs. changes in biochemical markers of bone formation and resorption were comparable in patients with quadriplegia and paraplegia, except for a greater increase in quadriplegics in pyridinoline, expressed as a percentage of baseline. In conclusion, a marked increase in bone resorption and modest changes in bone formation occur after SCI, and possibly increased bone resorption occurs in quadriplegia.

Adolescent↗
PubMed1998

The fetal outcome in pregnancies with isolated reduced amniotic fluid volume in the third trimester.

Our aim was to assess the outcome of pregnancies where oligohydramnios, defined by a published gestational reference range for amniotic fluid index, was the only abnormal finding at third trimester scan, and all other ultrasound parameters including biometry were within normal limits at initial scan. A retrospective case-control study was performed at The Liverpool Maternity Hospital. 103 pregnancies with reduced amniotic fluid index in the third trimester and apparently normal fetal growth profile ultrasonographically were identified from ultrasound reports throughout 1993. Pregnancies in the third trimester with normal amniotic fluid index on index scan were also identified from these reports and 103 were matched for parity, gestational age at delivery, mode of onset of labour, presentation at labour and medical conditions. Exclusion criteria were ruptured membranes, fetal abnormalities, estimated fetal weight below the fifth centile at index scan and multiple pregnancies. The outcome criteria were birthweight, Apgar scores at delivery, induction and emergency delivery for fetal reasons and admission to Neonatal Intensive Care Unit. Statistical analysis was performed by Fisher's exact test and Gart's odds ratio. Compared with controls, pregnancies in the reduced liquor group had a higher number of babies below the 5th centile (odds ratio 5.2, 95% confidence interval 1.6 to 22), a higher risk of induction for fetal reasons (odds ratio 34.4, 95% confidence interval 5.35 to 1425.5) and admission to Neonatal Intensive Care Unit (odds ratio 9.77, 95% confidence interval 1.3 to 432). Any observed difference in the need for emergency delivery due to fetal reasons was not clinically significant (odds ratio 2.16, 95% confidence interval 0.77 to 6.6) The definition used for oligohydramnios used in this study appears to identify a group of babies with a fourfold risk of low birthweight and a high risk of admission to the Neonatal Intensive Care Unit and induction of labour for fetal reasons. This would suggest that pregnancies with isolated oligohydramnios require some form of fetal monitoring and further prospective studies are required to determine the most appropriate method.

Apgar Score↗
PubMed1998

Function after anterior cruciate ligament injuries. Influence of visual control and proprioception.

Information about limb positions and movements consists of input from visual, vestibular, cutaneous, muscular, tendinous and joint receptors, but the relative contribution from each type and location of receptors is not known. The aim of this study was: a) to measure the contribution from visual control on extremity function, as measured with a one-leg hop test in healthy persons, in patients with an asymptomatic ACL injury, after non-operative treatment and in patients with a stable knee after an ACL reconstruction, b) to investigate if there was any relation between proprioception from the extremity, as measured with the threshold for detecting passive motion of the knee, and the one-leg hop test with a gradual decrease in visual control. There was a decrease in hop-length when the subjects were deprived of visual control that was significant when the dominant eye or both eyes were blinded, both in the 2 patient groups and the reference population. The magnitude of the length reduction did not differ between the groups or between injured and healthy limbs. In all 4 threshold tests performed as a measure of peripheral proprioception, a stronger relation to hop-length was recorded for the blinded hop than with full visual control in the patients with nonoperated ACL injuries. The coefficients of correlation between hop-length and the proprioceptive recordings in the injured limb were of the same magnitude as on the healthy side.

Adult↗
PubMed1998

The effect of cardiopulmonary bypass on blood cell filterability in children undergoing cardiac surgery.

BACKGROUND: The extended use of cardiopulmonary bypass (CPB) in cardiac surgery is limited because of damage to blood which in adults has been assessed by alterations in blood cell rheology. Blood trauma assessment in children is difficult because of the restrictions in sample volume and frequency but needs to be established from time to time in order to study the tolerance to new surgical and extracorporeal techniques. MATERIALS AND METHODS: Fourteen pediatric patients undergoing cardiac surgery with CPB for congenital heart disease corrections were studied. Whole blood, red blood cell and white blood cell rheology (filterability) were monitored before, during and after CPB using the St. George filtrometer that used small amounts of blood. RESULTS: The results showed that all the rheologic parameters were altered during the blood trauma of CPB and were outside the reference values before, during and after CPB. CONCLUSIONS: This suggested that blood cell rheologic disturbances did not recover soon after CPB and this may be of interest in long term follow-up to understand responses and recovery patterns to disease and interventions associated with pediatric heart surgery using CPB.

Blood Cell Count↗
PubMed1998

Modification of the standard method used in the United Kingdom for counting Escherichia coli in live bivalve molluscs.

The standard method for counting Escherichia coli in live bivalve molluscs is labour intensive and takes three days to obtain a result. Modifications to the standard method were investigated in a collaborative trial conducted in five centres. No significant difference was found between results based on the presence of acid at 24 hours (h) in first stage tests and those based on the presence of acid and gas after 48 h (standard method). The use of the chromogenic medium BCIG (5-bromo-4-chloro-3-indolyl-beta-D glucuronide) agar incubated at 44 degrees C to confirm first stage tests was also found to give equivalent results to conventional confirmation tests. The preferred, modified method removes the presence of gas as a criterion of detection, uses a chromogenic agar medium to confirm the presence of E. coli, and gives results within 48 h. A distribution of simulated samples and selected strains of E. coli to other laboratories using the PHLS external quality assurance scheme for shellfish found no significant difference between results obtained by the standard and modified methods.

Animals↗
PubMed1998

Computerized dynamic visual acuity test in the assessment of vestibular deficits.

OBJECTIVE: The study was designed to measure dynamic visual acuity (DVA) during head movement as an assessment of the functional impact of vestibular deficits. STUDY DESIGN: The study design was a prospective, clinical study. SETTING: The study was performed in a tertiary, ambulatory referral center. PATIENTS: Forty-two normal subjects, 29 patients with unilateral vestibular loss, and 26 patients with bilateral vestibular hypofunction who were 19-87 years of age were examined. INTERVENTION: Diagnostic intervention was performed. MAIN OUTCOME MEASURE: Main outcome measures included the reliability, sensitivity, and specificity of a computerized test that measures visual acuity during head movement in normal subjects and in patients with vestibular deficits. RESULTS: The computerized DVA test was reliable in both normal subjects (intraclass correlation coefficient [ICC] r=0.87) and in patients with vestibular deficits (ICC r=0.83). The sensitivity of the DVA test was 94.5% and the specificity was 95.2%. The positive predictive value (individuals who test positive on the DVA test who will have a vestibular deficit) was 96.3%. The negative predictive value (individuals who test negative on the DVA test who will not have a vestibular deficit) was 93%. CONCLUSIONS: The computerized DVA test is reliable and is able to distinguish among normal subjects and patients with vestibular deficits.

Adult↗
PubMed1997

Intercellular adhesion molecule-1 and CD36 synergize to mediate adherence of Plasmodium falciparum-infected erythrocytes to cultured human microvascular endothelial cells.

We have compared the adhesion of Plasmodium falciparum-infected erythrocytes to human dermal microvascular endothelial cells (HDMEC) and human umbilical vein endothelial cells (HUVEC) and have assessed the relative roles of the receptors CD36 and intercellular adhesion molecule-1 (ICAM-1). HUVEC (a cell line that expresses high levels of ICAM-1 but no CD36) mediate low levels of adhesion, whereas HDMEC (which constitutively express CD36) mediate high levels of adhesion even before ICAM-1 induction ICAM-1 expression leads to yet greater levels of adhesion, which are inhibited both by anti-ICAM-1 and CD36 mAbs, despite no increase in the expression of CD36. The results indicate the presence of a substantial population of infected cells that require the presence of both receptors to establish adhesion. Synergy between these receptors could be demonstrated using a number of parasite lines, but it could not be predicted from the binding of these same parasite lines to purified ICAM-1 and CD36. This phenomenon could not be reproduced using either purified receptors presented on plastic, or formalin-fixed HDMEC, suggesting that receptor mobility is important. This is the first study to demonstrate receptor synergy in malaria cytoadherence to human endothelial cells, a phenomenon necessary for parasite survival and associated with disease severity.

Animals↗
PubMed1997

Skin cancer prevention.

The Health of the Nation objectives for skin cancer will only be achieved through prevention and early detection. The key Health of the Nation objective to halt the year on year increase in skin cancer by 2000 means that this ambitious target must be tackled through a multidisciplinary approach. In this article, the authors suggest that most future strategies for reducing skin cancer will be based in primary care and some of these will be led by nurses.

Health Priorities↗
PubMed1997

Identification of a zinc-finger gene at 6q25: a chromosomal region implicated in development of many solid tumors.

We have used a rat model of epithelial ovarian cancer to identify a gene that shows decreased or lost expression in independently transformed rat ovarian surface epithelial cell lines compared to the normal progenitor cells. Hence, we refer to this gene as Lot-1 (Lost on transformation 1, GenBank accession no. U72620). Here, we report the cloning of the likely human homologue and its initial characterization. The deduced amino acid sequences of the cDNAs for rat and human LOT-1 (GenBank accession no. U72621) contain seven zinc finger motifs of the C2H2 type as well as proline and glutamine rich areas. The genes share 76.4% identity at the nucleotide level, 67.7% at the amino acid level and 85.5% within the seven zinc finger motifs. LOT-1 is ubiquitously expressed in normal human tissues but was not expressed in four of 11 (36%) human ovarian cancer cell lines or spontaneously transformed human ovarian surface epithelial cells. The human gene maps to chromosome 6 at band q25. We show that there is a 38% incidence of allelic loss at this chromosomal location in human ovarian cancers. This chromosomal region has also been implicated in the genesis of breast, kidney, and pleural mesothelial cancers. We suggest that this newly identified gene is not only of intrinsic interest as a ubiquitously expressed probable transcription factor but is a plausible candidate for the tumor suppressor gene which likely resides in the region of chromosome 6 defined by band q25.

Amino Acid Sequence↗
PubMed1997

Synthesis and evaluation of 2-(arylamino)imidazoles as alpha 2-adrenergic agonists.

A series of 2-(arylamino)imidazoles was synthesized and evaluated for activity at alpha 1- and alpha 2-adrenoceptors. This class of agents has been shown to have potent and selective agonist activity at the alpha 2-adrenoceptors. The most potent member of this class, 2-[(5-methyl-1,4-benzodioxan-6yl)amino]imidazole, proved efficacious for the reduction of intraocular pressure upon topical administration and for the reduction of blood pressure upon intravenous administration. During the course of our studies, we developed a new reagent that allowed rapid assembly of the target compounds. This reagent, N-(2,2-diethoxyethyl)carbodiimide, was convenient to prepare and was stable under low-temperature storage conditions.

Adrenergic alpha-2 Receptor Agonists↗
PubMed1997

Proprioception after an acute knee ligament injury: a longitudinal study on 16 consecutive patients.

A defect in proprioception has been found in selected patient groups that have an anterior cruciate ligament deficient knee at different times after the original injury. The time of development and the extent of such defects were studied longitudinally on 16 consecutive patients. During the first year after a primary knee injury, which included a complete rupture of the anterior cruciate ligament, we repeatedly performed three tests of proprioception: (a) one to determine the threshold for detecting a passive motion from starting positions of 20 and 40 degrees, (b) an active reproduction of a passive angular change, and (c) a visual estimation of a passive angular change. The injured limb was compared with the uninjured limb and with the limbs of an age-matched reference group of healthy subjects. The population did not have a normal distribution, and some patients had consistently extreme recordings in the threshold tests at the various times of testing. Significant differences were found between the groups at the starting position of 20 degrees, when the injured knee was compared with the uninjured knee, after 1 month (p = 0.05), and after 2 months (p = 0.03). There was a trend toward a higher threshold for detecting a passive motion when the injured side was compared with the knees of the reference group at 1 month (p = 0.06) but not later on. A similar pattern was found for the injured knee at the starting position of 40 degrees, but it was not significant. An impaired ability to detect a passive motion was registered for the nearly extended knee 1 and 2 months after a primary injury. In the active reproduction and visual estimation tests, no significant defects were found at any time during the first year in these consecutively studied patients.

Adolescent↗