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PubMed2004

Assessment of the metabolic activity of bone grafts with (18)F-fluoride PET.

PURPOSE: The aims of this prospective study were to evaluate quantitative approaches to (18)F-fluoride positron emission tomography (PET) imaging in allogenic bone grafts of the limbs, and to assess the time course of graft healing after surgery. METHODS: We performed a total of 52 dynamic (18)F-fluoride PET studies in 34 patients with cancellous and full bone grafts. Seven patients were imaged three times at 6, 12, and 24 months after surgery, and four patients were imaged twice. PET data were quantitatively analyzed using non-linear regression (NLR) analysis, Patlak analysis, and standardized uptake value (SUV). RESULTS: Fluoride bone metabolism in cancellous grafts decreased by 25% from 6 to 12 months post surgery, and revealed a total decrease of 60-65% after 2 years for SUV, K(Pat), and K(NLR). Full bone grafts first showed an increase by 20% from 6 to 12 months and from then on decreased to 70% of the initial activity at the end of 2 years with either quantification method. In two patients with non-union of their full bone grafts, increases in SUV, K(Pat), K(NLR), and K(1) far above average and outside the normal time pattern were observed. Highly significant correlations were found between SUV, K(Pat), K(NLR), and K(1) for both grafts and normal limb bones. In patients imaged repeatedly, the percentage changes in fluoride graft metabolism were also significantly correlated between SUV, K(Pat), and K(NLR). CONCLUSION: Quantitative (18)F-fluoride PET is a promising tool for assessment of fluoride metabolism and normal healing in bone grafts of the limbs.

Adolescent↗

PubMed2000

A comparison of nonlinear regression and neural network models for ground-level ozone forecasting.

A hybrid nonlinear regression (NLR) model and a neural network (NN) model, each designed to forecast next-day maximum 1-hr average ground-level O3 concentrations in Louisville, KY, were compared for two O3 seasons--1998 and 1999. The model predictions were compared for the forecast mode, using forecasted meteorological data as input, and for the hindcast mode, using observed meteorological data as input. The two models performed nearly the same in the forecast mode. For the two seasons combined, the mean absolute forecast error was 12.5 ppb for the NLR model and 12.3 ppb for the NN model. The detection rate of 120 ppb threshold exceedances was 42% for each model in the forecast mode. In the hindcast mode, the NLR model performed marginally better than the NN model. The mean absolute hindcast error was 11.1 ppb for the NLR model and 12.9 ppb for the NN model. The hindcast detection rate was 92% for the NLR model and 75% for the NN model.

Forecasting↗

PubMed2026

Diverse haplotypes at a complex Solanum americanum locus confer resistance to Phytophthora infestans and P. capsici.

Plants encounter diverse pathogens and have evolved a two-layered innate immune system to detect pathogen molecules and activate defense mechanisms that restrict infection. Most cloned plant Resistance (R) genes encode NLR immune receptors. NLR genes are often found in clusters of paralogs with sequence and copy number variation; whether these NLR clusters evolve in response to single or multiple pathogens has been unclear. We report here the isolation of a Phytophthora capsici resistance gene, Rpc2, along with a novel P. infestans resistance gene, Rpi-amr5, from two Solanum americanum accessions. These orthologous genes reside in the Rpi-amr1 cluster, which has previously been associated with resistance to P. infestans. By screening RXLR effector libraries of P. infestans and P. capsici, we identified multiple effectors recognised by both NLRs. Our findings highlight the complexity of NLR clusters and evolution driven by interactions with multiple pathogens. This work will underpin efforts to elevate resistance against Phytophthora pathogens and enhances our understanding of NLR evolution.

Journal Article↗

PubMed2005

(18)F-fluoride PET for monitoring therapeutic response in Paget's disease of bone.

UNLABELLED: A prospective study was undertaken to evaluate PET with (18)F-fluoride for monitoring the response to bisphosphonates in Paget's disease of bones. METHODS: Fourteen patients with a monostotic (n = 9) or a polyostotic form (n = 5) of Paget's disease were scanned at baseline and at 1 and 6 mo after the beginning of treatment. Dynamic acquisition and arterial blood sampling were used to calculate the influx constant Ki (by both the Patlak [Ki-PAT] method and the nonlinear regression [Ki-NLR] method). Kinetic modeling was compared with maximal standardized uptake values (SUV(max)) and biochemical markers of bone remodeling. RESULTS: Baseline uptake of (18)F-fluoride by pagetic bones was significantly higher than in normal bones (P < 0.05). One month after the start of treatment, SUV(max), Ki-PAT, Ki-NLR, and K(1) (the unidirectional clearance of fluoride from plasma to the whole of the bone tissue) decreased significantly by 27.8%, 27.9%, 27.5%, and 23.6%, respectively. Biochemical markers were already normalized in 6 of 9 patients with monostotic disease, although all had high (18)F-fluoride uptake values. Six months after the start of treatment, (18)F-fluoride uptake further diminished by 22.3%-25.6%. Biochemical markers were normal in all but 2 patients, although 10 of 14 patients still showed high (18)F-fluoride uptake. One patient did not respond to treatment and maintained high uptake of (18)F-fluoride throughout the study. SUV(max) correlated with both Ki-PAT and Ki-NLR at baseline, 1 mo, and 6 mo (P < 0.05). Moreover, the change of SUV(max) between baseline and 1 mo, as well as between baseline and 6 mo, also correlated with the change of Ki-PAT and Ki-NLR (P < 0.05). CONCLUSION: Our results show that (18)F-fluoride PET can be used to noninvasively and accurately monitor the efficacy of treatment with bisphosphonates in Paget's disease of bones. SUV(max) correlates with Ki-PAT and Ki-NLR and, interestingly, varies in the same manner as kinetic indices. Therefore, the use of SUV(max) could avoid the need for dynamic acquisition and arterial blood sampling and would facilitate the use of whole-body PET in a clinical setting.

Adult↗

PubMed2005

Clinical validity of a negative computed tomography scan in patients with suspected pulmonary embolism: a systematic review.

CONTEXT: The clinical validity of using computed tomography (CT) to diagnose peripheral pulmonary embolism is uncertain. Insufficient sensitivity for peripheral pulmonary embolism is considered the principal limitation of CT. OBJECTIVE: To review studies that used a CT-based approach to rule out a diagnosis of pulmonary embolism. DATA SOURCES: The medical literature databases of PubMed, MEDLINE, EMBASE, CRISP, metaRegister of Controlled Trials, and Cochrane were searched for articles published in the English language from January 1990 to May 2004. STUDY SELECTION: We included studies that used contrast-enhanced chest CT to rule out the diagnosis of acute pulmonary embolism, had a minimum follow-up of 3 months, and had study populations of more than 30 patients. DATA EXTRACTION: Two reviewers independently abstracted patient demographics, frequency of venous thromboembolic events (VTEs), CT modality (single-slice CT, multidetector-row CT, or electron-beam CT), false-negative results, and deaths attributable to pulmonary embolism. To calculate the overall negative likelihood ratio (NLR) of a VTE after a negative or inconclusive chest CT scan for pulmonary embolism, we included VTEs that were objectively confirmed by an additional imaging test despite a negative or inconclusive CT scan and objectively confirmed VTEs that occurred during clinical follow-up of at least 3 months. DATA SYNTHESIS: Fifteen studies met the inclusion criteria and contained a total of 3500 patients who were evaluated from October 1994 through April 2002. The overall NLR of a VTE after a negative chest CT scan for pulmonary embolism was 0.07 (95% confidence interval [CI], 0.05-0.11); and the negative predictive value (NPV) was 99.1% (95% CI, 98.7%-99.5%). The NLR of a VTE after a negative single-slice spiral CT scan for pulmonary embolism was 0.08 (95% CI, 0.05-0.13); and after a negative multidetector-row CT scan, 0.15 (95% CI, 0.05-0.43). There was no difference in risk of VTEs based on CT modality used (relative risk, 1.66; 95% CI, 0.47-5.94; P = .50). The overall NLR of mortality attributable to pulmonary embolism was 0.01 (95% CI, 0.01-0.02) and the overall NPV was 99.4% (95% CI, 98.7%-99.9%). CONCLUSION: The clinical validity of using a CT scan to rule out pulmonary embolism is similar to that reported for conventional pulmonary angiography.

Humans↗

PubMed2004

Mini-laparoscopic appendectomy using a needle loop retractor offers optimal cosmetic results.

BACKGROUND: Do conventional laparoscopic appendectomy (LA) techniques provide truly satisfying results for patients and surgeons? We have devised a more advanced technique that improves cosmesis. METHODS: A 2-mm scope is inserted at the umbilicus, and a 12-mm working trocar is inserted through a suprapubic incision placed below the line of pubic hair. A needle loop retractor (NLR) is inserted to hold the appendix in the lower right abdomen. In this NLR, a stainless steel wire is placed within a needle having a diameter of 2 mm. From the suprapubic trocar, a bipolar coagulator is inserted to transect the appendiceal mesentery. A series of 30 patients underwent this procedure. RESULTS: There were no conversions to laparotomy and no intra- or postoperative complications. CONCLUSIONS: Laparoscopic appendectomy using a 2-mm scope, suprapubic trocar, and an NLR yields optimal cosmetic results. For surgeons, the NLR allows the appendix to be held more firmly than then a 5- or 2-mm grasping forceps is used.

Adult↗

PubMed2005

Nonlinear regression and ARIMA models for precipitation chemistry in East Central Florida from 1978 to 1997.

Continuous monitoring of precipitation in East Central Florida has occurred since 1978 at a sampling site located on the University of Central Florida (UCF) campus. Monthly volume-weighted average (VWA) concentration for several major analytes that are present in precipitation samples was calculated from samples collected daily. Monthly VWA concentration and wet deposition of H(+), NH(4)(+), Ca(2+), Mg(2+), NO(3)(-), Cl(-) and SO(4)(2-) were evaluated by a nonlinear regression (NLR) model that considered 10-year data (from 1978 to 1987) and 20-year data (from 1978 to 1997). Little change in the NLR parameter estimates was indicated among the 10-year and 20-year evaluations except for general decreases in the predicted trends from the 10-year to the 20-year fits. Box-Jenkins autoregressive integrated moving average (ARIMA) models with linear trend were considered as an alternative to the NLR models for these data. The NLR and ARIMA model forecasts for 1998 were compared to the actual 1998 data. For monthly VWA concentration values, the two models gave similar results. For the wet deposition values, the ARIMA models performed considerably better.

Acid Rain↗

PubMed2006

Reduction of paracetamol metabolism after hepatic resection.

INTRODUCTION: Paracetamol is often used as an analgesic following hepatic resection. During liver resection, vascular clamping is carried out to reduce blood loss. Previous studies have described transient postoperative rises in serum aminotransferase levels and decreases in prothrombin time and factor V levels. We have examined paracetamol metabolism after liver resection. METHODS: A prospective observational study was performed. All patients undergoing liver resection were included. Propacetamol was given every 6 h. Blood samples for plasma paracetamol concentrations were collected before, 1 h after the end of the first injection (T1), just before the second injection (6 h: T6), and just before the fifth injection (24 h: T24). RESULTS: 37 patients were recruited. 13 had hepatic vascular exclusion (HVE group), 13 had portal triad clamping (PTC group) and 11 had abdominal surgery with no liver resection (NLR group: control group). At T6, the plasma paracetamol concentration in the HVE group was significantly higher than in the NLR groups; at T24, this concentration was significantly higher in the HVE group than in the NLR and PTC groups, and was higher in the PTC group than in the NLR group. Prothrombin time and factor V was significantly lower in the HVE group than in the PTC group on the first postoperative day. DISCUSSION: This study showed a reduction of paracetamol metabolism in the liver resection group with significantly increased paracetamol levels. However, the maximum mean plasma concentration reached was not clinically or toxicologically significant. For these reasons, we cannot suggest that paracetamol should or should not be avoided in patients undergoing liver resection.

Acetaminophen↗

PubMed2006

NALP3: a key player in caspase-1 activation.

The NLR (NACHT-LRR) family of proteins have been implicated in the regulation of immune responses and cell death pathways. Some NLR family members can form multiprotein complexes, called inflammasomes, involved in the activation of pro-inflammatory caspases. Mutations in the NALP3/CIAS1/cryopyrin gene, a member of the NLR family, are linked to three auto-inflammatory disorders: Muckle-Wells syndrome, familial cold auto-inflammatory syndrome and neonatal-onset multisystem inflammatory disease. NALP3 along with the adaptor molecule ASC activates caspase-1 in response to a wide variety of stimuli. Here we review recent findings on the biology of NALP3 suggesting that it has functions beyond that of pathogen recognition.

Animals↗

PubMed2004

Attenuation of nicotine's discriminative stimulus effects in rats and its locomotor activity effects in mice by serotonergic 5-HT2A/2C receptor agonists.

RATIONALE: Reports have indicated that administration of nicotine inhibits, while withdrawal of chronically administered nicotine augments effects of serotonergic 5HT2A/2C agonists. OBJECTIVE: It was our objective to determine whether 5HT2A/2C agonists can modulate the discriminative stimulus effects of nicotine in rats or its locomotor activity effects in mice. METHODS: Adult male Sprague-Dawley rats were trained to discriminate 0.3 mg/kg nicotine base from saline in a two-lever, fixed-ratio (FR10), food-reinforced, operant-conditioning task during daily (Monday-Friday) 15-min experimental sessions. After characterizing a dose-response curve for nicotine, we tested the ability of the 5HT(2A/2C) agonists (+/-)-1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane HCL (DOI; 0.18-1.0 mg/kg) and 1-(4-bromo-2, 5-dimethoxyphenyl)-2-aminopropane (DOB; 0.1-1.0 mg/kg), the 5HT2C agonist 6-chloro-2-(1-piperazinyl)pyrazine hydrochloride (MK 212; 0.1 mg/kg-1.0 mg/kg), and the 5HT1A agonist (+/-)-8-hydroxy-2-(di-n-propylamino)tetralin hydrobromide (8-OH-DPAT; 0.01 mg/kg-1.0 mg/kg) to modulate nicotine's discriminative stimulus effects. After finding that DOI was able to attenuate the percentage nicotine lever responding (%NLR), we tested for it to also reverse nicotine's effects on locomotor activity in mice. RESULTS: The 5HT2A/2C agonists-in particular DOI-dose dependently attenuated %NLR. The effects of DOI were reversed by the 5HT2A/2C antagonist ketanserin. MK 212 and 8-OH-DPAT had irregular effects among rats and only reduced %NLR to below 50% levels at doses markedly suppressing responding. DOI also dose dependently blocked nicotine's acute rate-lowering locomotor activity effects. CONCLUSIONS: These results indicate that activation of serotonin 5HT2A/2C receptors can blunt the discriminative stimulus and locomotor activity effects of nicotine and presents the possibility that activation of these receptors might also be able to attenuate other effects of nicotine.

8-Hydroxy-2-(di-n-propylamino)tetralin↗

PubMed2004

Comparison of methodologies for the in vivo assessment of 18FLT utilisation in colorectal cancer.

Fluorine-18 3'-deoxy-3'-fluorothymidine (18FLT) is a tissue proliferation marker which has been suggested as a new tumour-specific imaging tracer in positron emission tomography (PET). The objectives of this study were to investigate the pharmacokinetics of 18FLT in patients with colorectal cancer, defining methodologies for the quantitative analysis of the in vivo 18FLT uptake and subsequently assessing the accuracy of semi-quantitative measures. Dynamic acquisitions over a single field of view of interest identified by computed tomography were carried out for up to 60 min following injection of 18FLT (360 +/- 25 MBq). Dynamic arterial blood sampling was carried out in order to provide a blood input function. Simultaneous venous samples were also taken in order to investigate their potential utilisation in deriving a hybrid input function. Arterial and venous blood samples at 5, 15, 30, 60 and 90 min p.i. were used for metabolite analysis. Eleven patients with primary and/or metastatic colorectal cancer were studied on a lesion by lesion basis (n = 21). All acquired images were reconstructed using ordered subsets expectation maximisation and segmented attenuation correction. Time-activity curves were derived by image region of interest (ROI) analysis and image-based input functions were obtained using abdominal or thoracic aorta ROIs. Standardised uptake values (SUVs) were calculated to provide semi-quantitative indices of uptake, while non-linear regression (NLR) methodology in association with a three-compartment model and Patlak analysis were carried out to derive the net influx constant Ki. The metabolite analysis revealed two radioactive metabolites, with the parent compound representing approximately 80% of the total radioactivity in the 30-min plasma sample. In the case of NLR, better fits were obtained with a 3k model (i.e. k4 = 0) for both lesion and bone marrow time-activity curves. For the same lesions, a high correlation was observed between the Ki derived from either Patlak analysis or NLR(3k) and the corresponding SUVs. Our results also suggest that the quantitative behaviour of 18FLT in vivo (up to 60 min p.i.) may be characterised using a 3k model or Patlak analysis in combination with image-derived input functions. The good correlation found between the SUVs (at 60 min) and Ki values supports the use of semi-quantitative indices to assess the proliferation rate of colorectal cancer lesions in vivo with 18FLT.

Aged↗

PubMed2006

Diagnosis of infection in hip and knee revision surgery: intraoperative frozen section analysis.

UNLABELLED: In this study we validated intraoperatively the analysis of polymorphonuclear leucocyte frozen sections for diagnosis of infection in hip and knee revisions. Between 1996 and 2002 we examined sections and cultured periprosthetic tissues in prosthetic revision in 170 cases, including 146 cases (83 hips and 63 knees). We assessed sensitivity (SE), specificity (SP), positive predictive value (PPV), negative predictive value (NPV), Youden index, positive likelihood ratio (PLR) and negative likelihood ratio (NLR). We compared intraoperative findings and paraffin-embedded samples. The results in the knee group were SE=66.7%, SP=89.7% [95% confidence interval (CI)], PPV=81% (95% CI), NPV=81.4% (95% CI), Youden index=0.56, PLR=6.5 (95% CI) and NLR=0.4 (95% CI). In the paraffin-embedded samples the results were SE=91%, SP=87% (95% CI), PPV=81% (95% CI), NPV=94% (95% CI), PLR=7 (95% CI) and NLR=8.7 (95% CI). We found a significant difference. The results in the hip group were SE=50%, SP=100% (95% CI), PPV=100% (95% CI), NPV=94.9% (95% CI), Youden index=0.5 and PLR=0.5 (95% CI). In hip and knee prosthetic revision surgery the presence of polymorphonuclear cells correlates with infection, but their absence does not exclude it. It is a quick and inexpensive test that should be included in the diagnostic protocol in revision surgery. LEVEL OF EVIDENCE: diagnostic Study (investigating a diagnostic test), level I. See instructions to authors for a complete description of levels of evidence.

Aged↗

PubMed2005

Rubredoxin acts as an electron donor for neelaredoxin in Archaeoglobus fulgidus.

Archaeoglobus fulgidus neelaredoxin (Nlr) is an electron donor:superoxide oxidoreductase. The reaction of superoxide with reduced Nlr is almost diffusion-limited, but the overall efficiency for detoxifying superoxide in vivo depends on the rate of reduction of Nlr by electron donors. Here, we report the purification and characterization of the two type I rubredoxins from A. fulgidus (AF0880 and AF1349) and show that they act as efficient electron donors for neelaredoxin, in vitro, with a second-order rate constant of 10(7)M(-1)s(-1) at 10 degrees C and pH 7.2.

Amino Acid Sequence↗

PubMed2026

Association of time-averaged systemic immune-inflammation indices with in-hospital mortality after intracerebral hemorrhage: a retrospective study.

BACKGROUND: Systemic inflammation plays a central role in secondary brain injury following intracerebral hemorrhage (ICH). Although inflammatory indices such as the neutrophil-to-lymphocyte ratio (NLR), systemic immune-inflammation index (SII), and systemic inflammation response index (SIRI) are linked to poor outcomes, their associations with mortality are commonly assumed to be linear, potentially overlooking nonlinear patterns where mortality risk rises steeply at higher levels. METHODS: We conducted a retrospective study using the MIMIC-IV database, including 440 patients with non-traumatic ICH who were alive and remained in the ICU for at least 72 h after admission. Mean NLR, SII, and SIRI were calculated from measurements obtained during this period. Multivariable logistic regression and restricted cubic spline (RCS) analyses were applied to assess their independent and nonlinear associations with in-hospital mortality. Model discrimination and calibration were internally validated using 1,000 bootstrap resamples. RESULTS: The in-hospital mortality rate was 26.1%. After multivariable adjustment, NLR and SIRI remained independently associated with mortality. Patients in the highest SIRI quartile had the highest risk of death (aOR = 5.12; 95% CI: 2.57-12.24; p < 0.001). RCS analysis revealed a significant nonlinear association between SIRI and mortality (p-nonlinearity < 0.05), showing a steep risk increase at higher SIRI levels. Adding SIRI to the base model provided a modest improvement in discrimination (AUC 0.762 to 0.785, p = 0.045) and significantly improved risk reclassification (cNRI = 0.4778, p < 0.001; IDI = 0.0240, p = 0.0151). CONCLUSIONS: Among patients with ICH who met the 72-hour eligibility criterion, higher 72-hour average SIRI was independently associated with in-hospital mortality. As a time-averaged measure, SIRI should be interpreted as a dynamic marker integrating the initial inflammatory state and the early clinical course rather than as a purely baseline prognostic factor. Although adding SIRI to the base model modestly improved discrimination and risk reclassification, it should be considered a candidate prognostic marker requiring external validation before clinical application.

Humans↗

PubMedDate not supplied

Positron emission tomography using 2-deoxy-2-[18F]-fluoro-D-glucose for response monitoring in locally advanced gastroesophageal cancer; a comparison of different analytical methods.

PURPOSE: To determine the ability of 2-deoxy-2-[18F]-fluoro-D-glucose (FDG) positron emission tomography (PET) to monitor response in locally advanced gastroesophageal cancer (LAGEC). Additionally, optimal FDG-PET methods for response monitoring were selected. PROCEDURES: Sequential dynamic FDG-PET scans were performed in 13 patients with LAGEC (T2-3N0-1M0-1a) treated with neoadjuvant cisplatin and gemcitabine plus granulocyte macrophage colony stimulating growth factor at a three weekly schedule. The standard FDG-PET method, nonlinear regression (NLR), was compared with computed tomography (CT), endoscopic-ultrasound (EUS), and histopathology as well as with 21 simplified analytical FDG-PET methods. RESULTS: Five out of 12 operated tumors responded histopathologically with less than 10% residual tumorcells (42%). These had a higher decrease in FDG uptake compared with nonresponders (P=0.008). Early (after two cycles) and late (after completed induction therapy) response evaluation showed a specificity of 86% and 100%, respectively, and a sensitivity of 100%. Both FDG-PET and EUS were superior to CT. From 21 methods analyzing FDG uptake, the quantitative Patlak analysis, the simplified kinetic method (SKM), and the semiquantitative standardized uptake value corrected for bodyweight (SUV-BW) seemed to correlate best with NLR. CONCLUSIONS: FDG-PET reliably predicted response in LAGEC. FDG-PET measurements using Patlak analysis or the more clinical applicable SKM and SUV-BW were acceptable alternatives to NLR.

Esophageal Neoplasms↗

PubMed2005

Validity of screening for glaucomatous optic nerve damage using confocal scanning laser ophthalmoscopy (Heidelberg Retina Tomograph II) in high-risk populations: a pilot study.

PURPOSE: To evaluate whether confocal scanning laser ophthalmoscopy (Heidelberg Retina Tomograph II [HRT II], Heidelberg Engineering, Heidelberg, Germany) is a valid tool for the detection of glaucomatous optic nerve damage. DESIGN: Observational, cross-sectional, nonconsecutive study in Montreal, Canada. PARTICIPANTS: Three hundred three nonconsecutive, high-risk persons were enrolled during a 6-month period. METHODS: Participants underwent HRT II testing and a standard ophthalmologic examination, including gonioscopy, intraocular pressure measurement, and optic disc grading. MAIN OUTCOME MEASURES: Positive likelihood ratio (PLR) and negative likelihood ratio (NLR), sensitivities and specificities, positive predictive value (PPV) and negative predictive value (NPV), and kappa coefficients of agreement of Moorfields regression analysis (MRA), cup shape measure (CSM), height variation contour (HVC), and mean retinal nerve fiber layer thickness (MRNFL). RESULTS: Three hundred three participants were enrolled, and 291 were examined clinically; 21 (7.2%) were found to have glaucoma. Heidelberg Retina Tomograph II testing was performed successfully and was of acceptable quality in 531 of 601 eyes (88%). When MRA was compared with the clinically based diagnosis, the weighted kappa coefficient was kappa = 0.567 (95% confidence interval [CI], 0.42-0.71) for the right eye and kappa = 0.516 (95% CI, 0.37-0.66) for the left eye. Best kappa coefficient of agreement was seen when normals were grouped with suspects in both clinical and MRA diagnosis (kappa = 0.604; 95% CI, 0.409-0.799 in the right eye). Depending on the gold standard and test-positive definitions for glaucoma, specificity ranged from 87% to 97%, sensitivity from 25% to 100%, PPV from 28% to 68%, NPV from 84% to 100%, PLR from 5.0 to 19.2, and NLR from 1.3 to 6.2. When CSM, HVC, and MRNFLT were compared with clinical diagnosis, all outcome measures were found to have lower ranges: specificity from 46.9% to 83.7%, sensitivity from 36.5% to 76.9%, PPV from 6% to 36%, NPV from 80% to 99%, PLR from 0.8 to 4.0, NLR from 0.9 to 3.0. CONCLUSIONS: The results of this study suggest that a glaucoma screening program may be effective in detecting glaucoma when targeting high-risk populations. Heidelberg Retina Tomograph II testing may prove to be a useful tool in detecting glaucomatous optic nerve damage and could be used as part of a complete glaucoma screening protocol.

Cross-Sectional Studies↗

PubMed2001

A model for peak and width of signaling windows: Ips duplicatus and Chilo partellus pheromone component proportions--does response have a wider window than production?

Pheromone communication systems have a reliable signal with a restricted window of amounts and ratios released and perceived. We propose a model based on a Gaussian response profile that allows a quantification of the response peak (location of optimum) and a measure of the peak width (response window). Interpreting the Gaussian curve, fitted by nonlinear regression (NLR), as a standard normal distribution, the peak location equals the mean (it) and the window width equals 2 x the standard deviation (2sigma). The NLR procedure can provide an objective measure for both peak location and width for a wide range of data sets. Four empirical data sets as well as 10 literature data sets were analyzed. The double-spined spruce engraver, Ips duplicatus, was field tested in four populations to find the optimum proportion for attraction to the two male aggregation pheromone components, ipsdienol (Id) and (E)-myrcenol(EM), ranging from 0 to 100% of Id. Tests in Norway and the Czech Republic confirmed the preference of western populations for a blend between 50 and 90% Id. A population in Inner Mongolia showed a preference for traps with the 10 and 50% Id baits. The NLR fitted values for response peak and width (mu; 2sigma) were: Norway 0.64, 0.73; Czech Republic 0.53, 0.73; NE China 0.77, 0.29; and Inner Mongolia 0.33, 0.50. The signal produced by Norwegian field-collected males had a narrower window width (2sigma = 0.12). Males of the maize stem borer, Chilo partellus, were tested in a flight tunnel for their response to variation in the two major female sex pheromone gland components, (Z)- l1-hexadecenal and the corresponding alcohol (OH). Variation of the alcohol in seven levels from 2 to 29% OH showed the highest male response for 17% OH. For all behavioral steps, the peak of male response was near mu = 0.14, while the window width fell from 2sigma = 0.5 to 0.2 for eight sequential behavioral steps from take-off to copulation. Female production had a similar peak location (mu = 0.13) but a narrower width, 2sigma = 0.14. Literature data from other moth species showed similar patterns, with a wider male response relative to the female production windows. Literature data on response to enantiomer ratios in a hymenopteran and to pheromone amounts in a dipteran were also described by our model. In a bark beetle population (Ips pini), with two hybridizing enantiomeric strains, the production peaks were narrower (0.1) than the response peaks (0.5). Thus, it in general, seems that in the pheromone systems analyzed, the width of the response window (2sigma = 0.1 to 0.8) is larger than that of the production window (2sigma = 0.03 to 0.14), irrespective of the sex of the sender.

Animals↗

PubMed2004

Presliding friction identification based upon the Maxwell Slip model structure.

The problem of presliding friction identification based upon the Maxwell Slip model structure, which is capable of accounting for the presliding hysteresis with nonlocal memory, is considered. The model structure's basic properties are examined, based upon which a priori identifiability is established, the role of initial conditions on identification is investigated, and the necessary and sufficient conditions for a posteriori identifiability are derived. Using them, guidelines for excitation signal design are also formulated. Building upon these results, two new methods, referred to as Dynamic Linear Regression (DLR) and NonLinear Regression (NLR), are postulated for presliding friction identification. Both may be thought of as different extensions of the conventional Linear Regression (LR) method that uses threshold preassignment: The DLR by introducing extra dynamics in the form of a vector finite impulse response filter, and the NLR by relaxing threshold preassignment through a special nonlinear regression procedure. The effectiveness of both methods is assessed via Monte Carlo experiments and identification based upon laboratory signals. The results indicate that both methods achieve significant improvements over the LR. The DLR offers the highest accuracy, with the NLR striking a very good balance between accuracy and parametric complexity.

Journal Article↗