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Selected AbstractsPotentialities of quantile regression to predict ozone concentrationsENVIRONMETRICS, Issue 2 2009S. I. V. Sousa Abstract This paper aims: (i) to analyse the influence of ozone precursors (both meteorological variables and pollutant concentrations) on ozone concentrations at different ozone levels; and (ii) to predict next day hourly ozone concentrations using a new approach based on quantile regression (QR). The performance of this model was compared with multiple linear regressions (MLR) for the three following periods: daylight, night time and all day. QR as proven to be an useful mathematical tool to evidence the heterogeneity of ozone predictor influences at different ozone levels. Such heterogeneity is generally hidden when an ordinary least square regression model is applied. The influence of previous concentrations of ozone and nitrogen monoxide on next day ozone concentrations was higher for lower quantiles. When QR was applied, the wind direction (WD) was found to be significant in the medium quantiles and the relative humidity (RH) in the higher quantiles. On the contrary, using the MLR models, both variables were not statistically significant. Moreover, QR allowed more efficient previsions of extreme values which are very useful once the forecasting of higher concentrations is fundamental to develop strategies for protecting the public health. Copyright © 2008 John Wiley & Sons, Ltd. [source] Circadian patterns of gastric electrical and mechanical activity in dogsNEUROGASTROENTEROLOGY & MOTILITY, Issue 1 2008R. Aviv Abstract, Gastric motor function assessment, in humans and animals, is typically performed for short recording periods. The aim of this article was to monitor gastric electrical and motor activity in the antrum and fundus simultaneously, for long periods, using a new implantable system. Ten dogs were implanted with fundic and antral electrodes for assessment of impedance and electrical activity. Dogs were studied while in cages, for periods of 22,26 h. From late evening and until feeding on the next day, slow wave (SW) rhythm demonstrated a distinct pattern of intermittent pauses (mean duration = 22.8 ±4.1 s) that delineated groups of SW's. Phasic increases in fundic tone were seen mostly in association with SW pauses, and were highly correlated with antral contractions, R2 = 0.652, P < 0.05. The SW rate (events per minute) in the postprandial period, fasting and night time was 4.2 ± 0.2, 5 ± 0.2 and 4.7 ± 0.3, respectively, P < 0.05 postprandial vs other periods. Antral and fundic mechanical activities were highly correlated during fasting, particularly at night. This novel method of prolonged gastric recording provides valuable data on the mechanical and electrical activity of the stomach, not feasible by current methods of recording. During fasting, fundic and antral motor activities are highly correlated and are associated with periodic pauses in electrical activity. [source] Assessment of glycemic control by continuous glucose monitoring system in 50 children with type 1 diabetes starting on insulin pump therapyPEDIATRIC DIABETES, Issue 3 2004Dorothee Deiss Abstract:, Objective:, To report experience with a continuous glucose monitoring system (CGMS) and to identify factors influencing glycemic control in a large cohort of children and adolescents with type 1 diabetes and change to insulin pump therapy via continuous subcutaneous insulin infusion (CSII). Research design and methods:, In 50 patients [21 boys, 29 girls; median age 12.6 yr (range: 1.3,16.4 yr); diabetes duration 5.0 yr (0.2,13.3)], hemoglobin A1c (HbA1c) and ambulatory CGMS were performed before and 6 wk after starting CSII. Average glucose concentration per 24 h, during day and night time as well as number of excursions, duration, and area under the curve (AUC) of glucose values above 180 mg/dL and below 60 mg/dL were calculated from CGMS data. Simultaneously, metabolic control was documented by standardized self-monitoring of blood glucose (SMBG). Results:, In the total cohort, HbA1c improved from 8.1 ± 1.2% at baseline to 7.7 ± 0.9% after 6 wk of CSII (p < 0.001). This effect was more distinct in boys (8.0 ± 1.4 vs. 7.5 ± 1.1%, p = 0.007) than in girls (8.1 ± 1.1 vs. 7.8 ± 0.7%, p = 0.039) as well as in patients with poor glycemic control (HbA1c > 8.0%) at baseline (8.9 ± 0.6 vs. 8.1 ± 0.8%, p < 0.001) and in those older than 12 yr (8.2 ± 1.2 vs. 7.7 ± 1.0%, p < 0.001). At 6 wk of CSII, the values of glucose average per 24 h, AUC and time above 180 mg/dL, particularly during the day, improved. HbA1c was correlated with AUC above 180 mg/dL (r = 0.742, p < 0.001) and CGMS average glucose per 24 h (r = 0.628, p = 0.002), but to a lesser extent with SMBG values (r = 0.418, p = 0.054). Conclusion:, With the change to CSII, HbA1c improved significantly after 6 wk of therapy. CGMS usage provided additional information about glycemic control in these patients. [source] Postoperative pain relief using thoracic epidural analgesia: outstanding success and disappointing failuresANAESTHESIA, Issue 1 2001G. A. McLeod Six hundred and forty patients received epidural analgesia for postoperative pain relief following major surgery in the 6-year period 1993,1998. Although satisfactory pain relief was achieved in over two-thirds of patients for a median duration of 44 h after surgery, one-fifth of patients (133 individuals) still experienced poor pain relief. Almost one out of three patients (194 individuals) had a problem with their epidural. Eighty-three patients (13%) suffered a technical failure and 84 (13%) patients had their epidurals removed at night time when pain-free because of pressure on beds. Seven patients had their epidural replaced and subsequently experienced excellent pain relief for a median of 77 h. Lack of resources prevented a further 480 patients from receiving the potential benefits of epidural analgesia. These results would suggest that the practical problems of delivering an epidural service far outweigh any differences in drug regimens or modes of delivery of epidural solutions. [source] 2357: Autonomic nervous system and endothelial peripheral dysfunction in normal tension glaucoma patientsACTA OPHTHALMOLOGICA, Issue 2010J WIERZBOWSKA Purpose To define parameters of autonomic nervous system activity and peripheral vascular reactive hyperemia in normal tension glaucoma patients. Methods Ambulatory 24-hour electrocardiogram and blood pressure (BP) monitoring by using Lifecard CF and SpaceLab 90207-30 combined with occlusion provocation test were carried out in 54 NTG patients (44 women, mean age 59.7) and 43 matched control subjects (34 women, mean age 57.0). Heart rate variability (HRV) time and frequency domain parameters [low-frequency (LF), high-frequency (HR) and LF/HF ratio], and blood pressure variability (BPV) were calculated and analyzed for both study groups. Postocclusive hyperemia response parameters (TM - time to peak flow, TH ,half-time hyperaemia, TR ,time to rest flow, BZ-biological zero and MAX , maximum hyperemic response) were compared for patients with a nocturnal fall in mean BP (MPB) of less than 10% (non-dippers), of 10-20% (dippers) and of more than 20% (over-dippers) Results NTG patients demonstrated higher LF and LF/HF values for 24-hour period, day-time and night time than control subjects. There was no difference in BPV between study groups (10.4 ± 1.9 vs. 10.5 ± 2.1, p=0.790). In NTG patients, TH was significantly higher (79.0 ± 80.9 s vs. 51.5 ± 35.3 s, p=0.028) and BZ was significantly lower (2.3 ± 1.0 vs. 3.1 ± 2.0, p=0.009) as compared to the control group. There was statistically significant difference between NTG non-dippers, dippers and over,dippers in the BZ parameter (2.3 ± 0.9 vs. 2.7 ± 1.3 vs. 1.4 ± 0.4 p=0.024). Conclusion NTG patients exhibit abnormal ANS system activity and a different systemic hyperemia response as compared with healthy subjects. [source] | ||||||||||