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S Robinson

Publications and source records attributed to S Robinson.

At least 37 records · Page 2Linked to original sources
PubMed2004

Performance of a block detector PET scanner in imaging non-pure positron emitters--modelling and experimental validation with 124I.

The key performance measures of resolution, count rate, sensitivity and scatter fraction are predicted for a dedicated BGO block detector patient PET scanner (GE Advance) in 2D mode for imaging with the non-pure positron-emitting radionuclides 124I, 55Co, 61Cu, 62Cu, 64Cu and 76Br. Model calculations including parameters of the scanner, decay characteristics of the radionuclides and measured parameters in imaging the pure positron-emitter 18F are used to predict performance according to the National Electrical Manufacturers Association (NEMA) NU 2-1994 criteria. Predictions are tested with measurements made using 124I and show that, in comparison with 18F, resolution degrades by 1.2 mm radially and tangentially throughout the field-of-view (prediction: 1.2 mm), count-rate performance reduces considerably and in close accordance with calculations, sensitivity decreases to 23.4% of that with 18F (prediction: 22.9%) and measured scatter fraction increases from 10.0% to 14.5% (prediction: 14.7%). Model predictions are expected to be equally accurate for other radionuclides and may be extended to similar scanners. Although performance is worse with 124I than 18F, imaging is not precluded in 2D mode. The viability of 124I imaging and performance in a clinical context compared with 18F is illustrated with images of a patient with recurrent thyroid cancer acquired using both [124I]-sodium iodide and [18F]-2-fluoro-2-deoxyglucose.

Computer Simulation↗
PubMed2004

Increased leucine turnover in women during the third trimester of uncomplicated pregnancy.

Plasma amino acid concentrations decrease in pregnancy despite increased requirements for both maternal and fetal protein accretion. There are few published data on changes in amino acid turnover in pregnancy. The aim of this study is to test the hypotheses that (1) whole body nonoxidative leucine disposal (NOLD) is higher and (2) whole body oxidative leucine disposal (OLD) is lower in the third trimester of pregnancy than in the nonpregnant state. After an overnight fast 8 pregnant women between 33 and 35 weeks gestation had a primed infusion of labeled [1-(13)C] leucine and a prime dose of NaH(13)CO(3). Carbon dioxide production was measured using indirect calorimetry. Gas chromatography-mass spectrometry was used to determine (13)CO(2) enrichment of expired air and oxidative and nonoxidative leucine turnover by measuring (13)C keto-isocaproate plasma enrichment, which reflects intracellular leucine enrichment. Women acted as their own controls after the puerperium. Whole body leucine turnover expressed per unit body weight was increased in pregnancy (median [interquartile range or IQR]: pregnant = 103.1 [14.9] v nonpregnant = 90.1 [10.9] micromol/kg/h). The mean (+/-SD) of the differences was 11.4 +/- 5.6 micromol/kg/h, P =.0006. NOLD was increased in pregnancy (pregnant = 86.8 [10.1] v nonpregnant = 73.3 [9.5] micromol/kg/h). The mean (+/-SD) of the differences was 10.6 +/- 5.4 micromol/kg/h, P =.0008. OLD was not significantly altered in pregnancy (pregnant = 17.3 [4.5] v nonpregnant = 15.91 [2.4] micromol/kg/h). The mean (+/-SD) of the differences was 0.84 +/- 1.94 micromol/kg/h, P =.26. In conclusion, women have significantly higher NOLD in the third trimester of pregnancy than when not pregnant but there are no significant changes in OLD.

Adult↗
PubMed2004

Optimized 3 T EPI of the amygdalae.

The optimum parameters for single-shot gradient-recalled (GR) EPI-based fMRI studies of the limbic region are systematically established at 3 T via their ability to mitigate intravoxel dephasing-measured via SNR and T2* in the amygdalae-and their implications for temporal resolution (or brain coverage). Conventional imaging parameters (64 x 64 matrix size and 4-6 mm thick slices) are confirmed to be inadequate for functional studies at 3 T. Measurements of main magnetic field variations across the amygdalae suggest that such variations are equal in the craniocaudal and anterior-posterior directions, and slightly lower in the mediolateral direction, with this and other considerations leading us to conclude an oblique axial orientation to be most suitable. In-plane resolution of approximately 1.7 mm was sufficient to recover signal in the area of the amygdalae. SNR was found to peak at a slice thickness of between 2.0 and 2.5 mm, dependent on the subject. T2* time in the amygdalae was measured with a standard EPI protocol to be 22 +/- 3 ms. Using the optimized (high resolution) EPI protocol proposed here, the measured T2* time increased to 48 +/- 2 ms (compared with 43 +/- 3 ms for a reference FLASH scan), only slightly lower than the cortex (49 +/- 2 ms measured with optimized EPI and 52 +/- 2 ms with FLASH). The FLASH measurement of 43 ms is taken to be a suitable effective echo time (TE(eff)) to achieve maximum BOLD sensitivity in the amygdalae. Time series data acquired with these parameters showed a 60% increase in SNR in the amygdala over that obtained with a standard low-resolution protocol and suggest sufficient SNR and BOLD sensitivity to make functional studies feasible. Arteries, but no substantial draining veins, were found in high-resolution BOLD venograms of the region. Our results indicate that EPI protocols need to be carefully optimized for structures of interest if reliable results from single subjects are to be established in this brain region.

Adult↗
PubMed2004

Metabolic effects of Troglitazone in patients with diet-controlled type 2 diabetes.

BACKGROUND: In order to study the mechanisms of action of Troglitazone (TGZ) in vivo in Type 2 diabetes, its effects were studied on glucose metabolism, lipolysis and very low-density lipoprotein (VLDL) apolipoprotein B100 (apoB) kinetics. MATERIALS AND METHODS: A placebo-controlled, double-blind study was performed in 24 diet-treated patients randomized to receive TGZ 600 mg day(-1), TGZ 200 mg day(-1) or placebo for 8 weeks. Glucose and glycerol turnover were assessed after an overnight fast, and during sequential low-dose insulin infusions (0.01 U kg(-1) h(-1) followed by 0.015 U kg(-1) h(-1)) using 6,6-2H Glucose and 1,2,3-2H Glycerol. Very low-density lipoprotein apoB secretion was measured using l-13C-leucine, monitoring isotopic enrichment by gas chromatography-mass spectrometry. Treatment effects were analyzed by analysis of covariance, adjusting for baseline. RESULTS: Therapy resulted in a significant group differences in fasting plasma glucose adjusting for baseline (P=0.039). This was most evident at TGZ 600 mg daily [glucose decrease from (mean +/- SD) 9.2 +/- 2.7 to 6.6 +/- 0.9 mmol L(-1)]. HbA1c and insulin levels did not change significantly. Plasma nonesterified fatty acid (NEFA) levels decreased (P=0.045), most evidently at TGZ 200 mg daily, but glycerol was not significantly affected. Although no significant effects were observed on VLDL apoB or triglyceride concentrations, there were treatment differences in the absolute secretion rate of VLDL apoB of borderline (P=0.056) statistical significance, with a decrease observed at TGZ 600 mg daily [geometric mean, SD range, 0.94 (0.41-2.15) to 0.40 (0.14-1.13 mg kg(-1) h(-1))]. Very low-density lipoprotein apoB fractional secretion rate and pool size were unaffected. The VLDL triglyceride: apoB molar ratio differed between treatment groups (P=0.013), being higher in the TGZ 600 mg group [5714 (4128-7741) to 8092 (5669-11552)]. Neither glucose nor glycerol rates of appearance were significantly altered by TGZ and nor did TGZ affect their suppression by insulin. DISCUSSION: The PPARgamma agonist, troglitazone, decreases fasting glucose and NEFA levels in diet-treated Type 2 diabetes. It may also decrease VLDL particle secretion. These effects would be considered beneficial. The biological importance of the increase in VLDL-triglyceride enrichment warrants further study.

Apolipoprotein B-100↗
PubMed2004

A survey of factor prophylaxis in the Canadian haemophilia A population.

High-dose factor prophylaxis, defined as the infusion of 25-40 factor (F) VIII International Units (IU) kg bodyweight (bw)(-1)> or = x 3 per week, started at age 1-2 years of life in boys with severe haemophilia A prevents the development of significant bleed-related arthropathy. However, programmes of prophylaxis are very expensive and venous access is a challenge. To ascertain patterns of prophylaxis in Canada during the period of a global shortage of recombinant FVIII concentrate a survey was conducted in 2001. The response rate was 83% and the survey identified 247 inhibitor-negative haemophilia A cases receiving prophylaxis, defined as the regular administration of FVIII at least once weekly, from 14 Canadian haemophilia treatment centres. The median age of the group identified was 13 years (range: 1-65) and 95% of cases had severe haemophilia A defined by a circulating factor level of <1%. The median FVIII infusion dose was 26 (range: 16-33) IU kg(-1); infusions were administered > or = x 3 per week in 67% of cases. High-dose factor prophylaxis was used most frequently in boys <5 years of age (23 of 28 cases, 82%) as compared with 56% (56 of 100), 66% (40 of 61) and 62% (36 of 58) of males ages 5-12, 13-18 and >18 years. Prophylaxis accounted for 50% of the annual Canadian FVIII consumption and was a major driving force in the 10% increase (=19.3 million FVIII IU) in the FVIII consumption in Canada in the 4-year period 1999-2003. Given the economic implications of increased use of prophylaxis prospective studies are warranted to better define optimal prophylaxis regimens in the haemophilia A population.

Adolescent↗
PubMed2004

Understanding the social context of violent and aggressive incidents on an inpatient unit.

The English National Service Framework for Mental Health stipulates that the highest quality of health care should be provided for mental health service users. Incidents of aggression and violence militate against achieving that goal, yet such incidents are frequently reported in inpatient settings. Much research in this area reflects a dualistic, perpetrator/victim conceptualization of incidents. This study aimed to take a more systemic approach by treating violent and aggressive incidents as social interactions and by seeking to understand the social contexts in which they took place. In this paper we describe and discuss the main themes to emerge from 15 staff accounts of 11 incidents on one ward. A striking theme reflected throughout the interview data was the lack of staff engagement with clients, and particularly an inability to look at the world through clients' eyes in interpreting their behaviour. We conclude that the 'zero tolerance' campaigns currently being conducted in the UK in relation to aggression towards NHS staff are unlikely to succeed without attention to understanding why aggressive behaviour arises and identifying features of the caring environment that may contribute to it. Rather than adopting a position of 'zero tolerance', we argue that three steps are required following an aggressive incident: emotional support; critical reflection and learning; and the pursuit of accountability.

Aggression↗
PubMed2003

Clinical use of rituximab in haematological malignancies.

Rituximab is a chimeric human/mouse monoclonal antibody that is approved for the treatment of relapsed and refractory non-Hodgkin's lymphoma (NHL) and in combination with CHOP (cyclophosphamide, doxorubicin, vincristine, prednisone) chemotherapy as first-line therapy for diffuse large B-cell NHL, where it has shown the first survival advantage over CHOP alone in more than 20 years. Strategies to help define the optimal therapeutic usage of rituximab are being assessed, including first-line and maintenance or extended therapy, and the combination of rituximab with chemotherapy in indolent NHL. Emerging data suggest that earlier use may yield higher response rates, extended therapy can prolong remission, and the addition of rituximab to chemotherapy can increase clinical and molecular remission rates when compared with those achieved using chemotherapy alone. Studies in the peritransplant setting suggest a role for rituximab in vivo purging prior to transplant and/or maintenance rituximab as a means of clearing minimal residual disease. Rituximab has also shown activity in other B-cell disorders such as chronic lymphocytic leukaemia. The full potential of this immunotherapeutic agent remains to be defined in ongoing and future clinical trials.

Antibodies, Monoclonal↗
PubMed2003

Ultrasound-guided radiofrequency submucosal tongue-base excision for sleep apnoea: a preliminary report.

Surgery for sleep apnoea is challenging, particularly in patients with macroglossia. This has led us to develop a new procedure for reduction of the tongue base with low morbidity. Two types of bipolar radiofrequency probe were used via a percutaneous approach under an aseptic technique and general anaesthesia on 15 consecutive patients with retropalatal and retrolingual collapse. The lingual neurovascular bundles and probe were simultaneously identified with intraoperative real-time ultrasound to prevent neurovascular damage, and five patients had additional tongue mucosal suture advancement. All patients had previous or concurrent palatal surgery. The increase in cephalometric (retrolingual) posterior airspace (PAS) was 4 mm with a Spinevac wand and mucosal suture advancement, which is comparable to current-staged monopolar radiofrequency protocols requiring treatment for up to 6 months. Overall, 40% polysomnographic success was achieved, but it was 80% when additional phase 1 procedures were used. Morbidity was minimal with careful adherence to the perioperative care protocol.

Adult↗
PubMed2003

Relation between insulin kinetics and insulin sensitivity in pregnancy.

BACKGROUND: Different time-concentration profiles of plasma insulin following insulin modification of a frequently sampled intravenous glucose-tolerance-test (FSIVGTT) were observed in a study investigating maternal metabolism and fetal macrosomia. We aimed to investigate whether these differences were related to the volume of distribution of insulin, insulin clearance, or both. DESIGN: Forty-four women were studied between 33 and 35 weeks' gestation using an insulin-modified FSIVGTT. Specific insulin was assayed with an enzyme-linked immunosorbent assay. Insulin sensitivity was calculated using the minimal model and the homeostasis model assessment (HOMA). The volume of distribution and clearance of insulin were calculated from measurements between 2 and 155 min after insulin modification using a one-compartment model. RESULTS: In accordance with the method for deriving the volume of distribution, there was a significant negative correlation between the increment in insulin concentration and the volume of distribution (rho=-0.92, P<0.0001). The insulin increment was also related negatively to the clearance of insulin (rho=-0.88, P<0.0001). There was a significant correlation between the volume of distribution and both the insulin sensitivity index (rho=0.56, P<0.0001) and HOMA-%S (rho=0.30, P=0.048), and between the clearance of insulin and both the insulin sensitivity index (rho=0.83, P<0.0001)) and HOMA-%S (rho=0.34, P=0.025). CONCLUSION: The different time-concentration profiles of plasma insulin resulted from differences in the volume of distribution and clearance of insulin. There was a correlation between insulin kinetics and the insulin sensitivity index. Further research is required to investigate possible mechanisms by which insulin kinetics may be related to insulin sensitivity.

Enzyme-Linked Immunosorbent Assay↗
PubMed2003

Continuing education opportunities for recently qualified mental health diplomates.

While successive reports concerned with mental health services have emphasized the importance of continuing professional development for mental health nurses, there have been long-standing concerns about the provision of appropriate courses and opportunities for attendance. Drawing from a longitudinal study of the careers of a cohort of mental health diplomates, this paper focuses on fulfilment of their continuing education plans in the early post-qualification period. During the first 6 months, just under half the cohort had wanted to start a course but been unable to do so. For some, even at this early career stage, dissatisfaction with continuing education opportunities was cited as reason for leaving, or considering leaving, a first job. Reasons for starting courses included career progress and meeting the care-giving needs of the immediate work situation. Diplomates may need guidance on their continuing education needs; there was much uncertainty about plans to take courses and moreover, demand for courses which they had wanted to start but been unable to do so, was not always sustained.

Adult↗
PubMed2003

First magnetomyographic recordings of uterine activity with spatial-temporal information using 151 channel sensor array (SARA).

The lack of an effective method for the diagnosis and management of labor points to the need for a new device. SARA-SQUID Array for Reproductive Assessment, is capable of recording spatial-temporal biomagnetic activity. The SARA system is first of its kind in the world dedicated to maternal-fetal research. We non-invasively recorded the magnetomyographic (MMG) signals corresponding to the uterine electrical activity from 7 pregnant mothers. The detailed physiological information obtained simultaneously from 151 sensors spread over the entire abdomen, will help in understanding the origin and propagation of the uterine activity. This information could give us better insight into the mechanism of uterine contraction and may help in better diagnosis and management of labor.

Female↗
PubMed2002

Haemotoxicity of thiamphenicol in the BALB/c mouse and Wistar Hanover rat.

Chloramphenicol (CAP) is haemotoxic in man, inducing two forms of toxicity. First, a commonly-occurring, dose-related, reversible bone marrow depression, which develops during treatment. Second, a rarer aplastic anaemia (AA), developing after treatment, is irreversible, and often fatal. Thiamphenicol (TAP) was developed as a replacement for CAP; however, there are no toxicological investigations in the mouse or rat on the dose-related haemotoxicity of TAP, in repeat dose gavage studies. Therefore, we have conducted a comprehensive investigation in these species, administering TAP for 7-17 days, to define haematological changes. Female BALB/c mice were gavaged with TAP, daily for 7-17 days at 400-1500 mg/kg; female Wistar Hanover rats were dosed with TAP daily at 50-375 mg/kg for 9 or 10 days. Haematological changes were studied at 1, 7 and 14 days post-dosing. In mice at day 1, TAP caused decreases in RBC, HCT and Hb; reticulocytes and platelets were reduced; changes were dose-related and reversible. Marrow cell counts were reduced; marrow was hypocellular, with erythroid depletion and progenitor cell vacuolation; the myeloid/erythroid (M:E) ratio was increased. In the rat, changes were not as clear-cut; there was anaemia with indications of reduced reticulocyte and platelet counts, and evidence of decreased neutrophils and lymphocytes. Marrow erythroid cells were decreased, precursor cells vacuolated, and the M:E ratio increased. We conclude that TAP induced haematological changes in the mouse and rat, parallelling the dose-dependent, reversible marrow depression reported in man; TAP is more haemotoxic in the rat than in the mouse.

Anemia, Aplastic↗