Hyperbolic Correlation Research Articles

Risk and Energy Based Optimization for Fire Monitoring System in Utility Tunnel Using Cellular Automata

Fire is one of the biggest threats to the safety of utility tunnels, and establishing camera-based monitoring systems is conducive to early fire finding and better understanding of the evolution of tunnel fires. However, conventional monitoring systems are being faced with the challenge of high energy consumption. In this paper, the camera operation in a utility tunnel was optimized considering both fire risk and energy consumption. Three design variables were investigated, namely the camera sight, the number of cameras in simultaneous operation, and the duration of camera operation. Cellular automata were used as a simple but effective method to simulate the spread of fire in a utility tunnel. Results show that as the number of cameras in simultaneous operation increases, the probability of fire capture also increases, but the energy consumption decreases. A shorter duration of camera operation can lead to a higher probability of fire capture, and meanwhile, lower energy consumption. For the duration of camera operation shorter than or equal to the allowable time, the probability of fire capture is significantly higher than that for the duration longer than the allowable time. Increasing the camera sight will significantly increase the probability of fire capture and lower the total energy consumption when a blind monitoring area exists. The total energy consumption of a camera-based monitoring system roughly satisfies hyperbolic correlation with the duration of camera operation, while the probability of fire capture can be predicted based on the number of cameras in simultaneous operation through a power model. The optimal design for the modeled tunnel section is two cameras in simultaneous operation with a tangent monitoring area. The duration of camera operation should be as short as possible, at least shorter than the allowable time. The study is expected to provide a reference for the sustainable design of energy-saving utility tunnels with lower fire risk.

Capacity for thermal adaptation in Nile tilapia (Oreochromis niloticus): Effects on oxygen uptake and ventilation

Standard metabolic rate (SMR) and maximum metabolic rate (MMR) were determined for Nile tilapia acclimated to six different experimental temperatures from 18 °C to 38 °C. SMR increased exponentially with temperature, from 79.8 mg O2 kg−1 h−1 at 18 °C, to 255.1 mg O2 kg−1 h−1 at 38 °C (Q10 = 1.79). The main increase in Q10 occurred within the highest temperature range, whereas in the lower temperature from 18 °C to 22 °C, temperature did not significantly affect SMR. MMR showed a hyperbolic correlation with increasing temperature, rising from 240.5 mg O2 kg−1 h−1 at 18 °C to a peak of 373.8 mg O2 kg−1 h−1 at 30 °C, before decreasing again at higher temperatures. Absolute aerobic scope (AAS) peaked at 26.0 °C, which we conclude to be the optimal temperature for Nile tilapia. The optimal temperature range, defined as the thermal range where 80% or more of the metabolic scope (MS) can be maintained, occurred between 19.5 and 32.1 °C. The lower (TCMIN) and upper (TCMAX) critical temperatures occurred at 13.1 °C and 38.8 °C. Nile tilapia showed a 4-fold scope for increasing ventilation frequency from 24 opercular beats min−1 (OB min−1) during SMR at 18 °C, to a maximum of 100 OB min−1 which occurred during MMR at 34 °C. fV during MMR increased with temperature, but above 30 °C became uncoupled with MO2, as fish were unable to sustain their rates of oxygen consumption despite a high fV. There was a strong correlation between fV and SMR (r2 = 0.83) across all temperatures indicating that fV is a good predictor of SMR. However, the correlation between MMR and fV was weak (r2 = 0.06), due to a strong interacting effect of temperature. When selecting data from the thermal optimum range, a good correlation between fV and MO2 was obtained (r2 = 0.74).

Influence of hybrid nano-structures on thermal performance of shear rate dependent viscosity fluid over a heated rotating cone with Hall and ion slip currents

The fluid of shear rate dependent viscosity has totally different rheology and exhibits dynamics which play a key role in heat transfer rate and friction experienced by surface over which this type of fluid is considered in this study as this type of fluids are extensively used in thermal processes. The governing laws and constitutive equations for hyperbolic tangent fluid and thermo-physical relation correlation for hybridity of nano-structures are simultaneously solved via finite element method (FEM). The predictions are recorded, and outcomes are explained. It is found from outcomes that suspension of hybrid nano-structures is the most approximate technique for the enhancement of thermal performance of coolant (hyperbolic tangent fluid). The process of diffusion of wall momentum into fluid speeds down as viscosity decreases as a function of shear rate. It is predicted from simulations that mono nanofluid is less shear thinning than hybrid nanofluid. Hence, if it is desired to reduce shear thinning phenomenon, enhance the thermal performance and suspension of hybrid nano-structures are recommended. The results are validated by comparing them with already published benchmarks. The parameters are varied, and simulations are recorded in term of numerical values and graphical data. The rotation of micro-structures has shown significant reduction in angular velocity of mono and hybrid nanofluids. Angular field has depicted an increasing trend when vortex viscosity parameter is varied through increasing values. Temperature decreases as a result of an increase in thermal relaxation time. Hence, thermal memory effects play a significant role in controlling the thermal boundary layer thickness.

Drug Permeability Profiling Using the Novel Permeapad® 96-Well Plate.

Here, first experiences with a prototype tool for high throughput (passive) permeability profiling, a 96-well plate comprising the Permeapad® membrane, are reported. The permeabilities of a set of drugs were determined and compared to published measures of oral absorption, such as human fraction absorbed (Fa) and in vitro permeability values obtained using other tools. The tool consists of a 96-well bottom and screen plate with the artificial, phospholipid-based barrier (Permeapad®) mounted between the plates' lower and upper compartments. The permeability of 14 model compounds including high- and low-absorption drugs, cationic, anionic, zwitterionic and neutral molecules, was determined by quantifying the compounds' transport over time, deriving the steady-state flux from the linear part of the cumulative curves and calculating the apparent permeability (Papp). The membrane structure was investigated in a high-resolution digital light microscope. The Permeapad® 96-well plate was found suited to distinguish high and low absorption drugs and yielded a hyperbolic correlation to Fa. The Papp values obtained were congruent with those determined with in-house prepared Permeapad® in the Franz cell set-up. Furthermore, good to excellent correlations were seen with Caco-2 permeability (R2= 0.70) and PAMPA permeability (R2= 0.89). Microscopic investigation of the Permeapad® barrier revealed the formation of phospholipid vesicles and myelin figures in aqueous environment. The Permeapad® 96-well plate permeation set-up is a promising new tool for rapid and reproducible passive permeability profiling.

Hyperbolic Correlation between the Viscosity Arrhenius Parameters at Liquid Phase of Some Pure Newtonian Fluids and Their Normal Boiling Temperature

Viscosity is the most important characteristic of hydraulic fluid and which is influenced by pressure and temperature. Using statistical methods for correlation analysis and regression, eventual causal relationship between parameters of the Arrhenius-type equation and principally the boiling point of some classical Newtonian liquids is attempted. Empirical validation utilizing data on viscosity of pure Newtonian liquids studied at atmospheric pressure and at different ranges of temperature gives excellent statistical results. Indeed, we found a significant strong correlation between the Arrhenius activation energy (Ea), the Arrhenius temperature (TA), and the boiling point (Tb). Consequently, an original hyperbole-type equation modeling this relationship is proposed which allows the prediction of the boiling temperature and the type of isobaric liquid-vapor diagram through information on viscosity Arrhenius parameters values, only in liquid phase, and will be thus very useful in the handling of engineering data especially for the study of hydraulic components and systems efficiency.

Numerical Simulation of Particle Breakage of Granular Assemblies in Discrete Element Analyses

This paper presents numerical simulations of high‐pressure biaxial tests on breakable granular soils with the discrete element method. The 2D setting is more economic in terms of computational cost, which allows simulation with a larger number of particles with a wider size distribution. The results of breakable and unbreakable agglomerates show that particle breakage has a significant influence on the macro‐ and micromechanical behaviors of the assembly. Higher confining pressure and larger axial strain result in the variation of particle grading and agglomerate numbers. The evolution of bond breakage during shearing makes it possible to trace the failure process and breakage mechanism at the microlevel. The breakage energy is found to account for a small fraction of total energy input compared with friction energy. A hyperbolic correlation between relative particle breakage and total energy input per unit volume was established regardless of the influence of confining pressure.

Particle breakage in triaxial shear of a coral sand

This paper presents a laboratory experimental study to comprehensively investigate the characteristics of particle breakage using numerous triaxial tests on a coral sand. Coral is a highly crushable granular material which fills the gaps between more crushable and less crushable granular materials. The monotonic tests and cyclic tests were terminated at the designated axial strains and the designated cyclic numbers, respectively. The grain size distributions were measured by sieve analyses of the specimens after the triaxial tests were performed. The relative breakage and relative fractal dimension were used to quantify the particle breakage. The cause of particle breakage that increased with increasing isotropic consolidation stress was shown to be isotropic stress. An almost linear increase in particle breakage in relative breakage was found as axial strain increased, whereas the increase in particle breakage in relative fractal dimension showed upward convexity. More particle breakage occurred in denser samples. During consolidation to the identical mean effective stress, the anisotropic stress state played a bigger role in particle breakage than the isotropic stress state, but during shearing particle breakage occurred more sharply in the triaxial tests with the isotropic consolidation to the higher confining pressure. In the cyclic shearing, the particle breakage in relative breakage and relative fractal dimension increased in upward convexity as the cyclic number increased, but in upward concavity with increasing axial strain. A hyperbolic model was proposed to correlate the relative fractal dimension with the relative breakage for use with both monotonic and cyclic tests. In the monotonic tests, a hyperbolic model was proposed to correlate the particle breakage in relative breakage and relative fractal dimension with the plastic work per unit volume. It is proposed that the loading-mode-induced (i.e., monotonic loading and cyclic loading) different mechanism of particle breakage meant that this model could not be applicable in the cyclic tests. The results suggested that the hyperbolic correlation of the particle breakage in relative fractal dimension and the plastic work per unit volume is the most reliable method of interpreting the energy consumption characteristics of particle breakage. This approach takes the fractal nature of soil into consideration. A microscopic view of particle breakage is also effective for observing the evolution of particle breakage.

Numerical investigations on breakage behaviour of granular materials under triaxial stresses

The effect of particle breakage and intermediate principal stress ratio on the behaviour of crushable granular assemblies under true triaxial stress conditions is studied using the discrete element method. Numerical results show that the increase of intermediate principal stress ratio <TEX>$b(b=({\sigma}_2-{\sigma}_3)/({\sigma}_1-{\sigma}_3))$</TEX> results in the increase of dilatancy at low confining pressures but the decrease of dilatancy at high confining pressures, which stems from the distinct increasing compaction caused by breakage with b. The influence of b on the evolution of the peak apparent friction angle is also weakened by particle breakage. For low relative breakage, the relationship between the peak apparent friction angle and b is close to the Lade-Duncan failure model, whereas it conforms to the Matsuoka-Nakai failure model for high relative breakage. In addition, the increasing tendency of relative breakage, calculated based on a fractal particle size distribution with the fractal dimension being 2.5, declines with the increasing confining pressure and axial strain, which implies the existence of an ultimate graduation. Finally, the relationship between particle breakage and plastic work is found to conform to a unique hyperbolic correlation regardless of the test conditions.

Numerical Solution of Single Piles Subjected to Pure Torsion

Torsional load on pile foundations is induced by the action of eccentric horizontal forces on the supporting structures. Such loading not only initiates twist at the pile head, but also reduces its axial capacity significantly associated with increased settlement of the foundation. Inadequate design of piles under torsion may lead to disastrous consequences. Although several theoretical and experimental investigations have already been carried out on piles under torsional load as evidenced from the available literature, there is ample scope for further contributions on the influence of torsional load on pile foundation. This paper presents a novel numerical model (boundary element method) to analyze the response of a single, vertical, floating pile subjected to pure torsional load. The nonlinear stress-strain response of soil has been incorporated in the model by hyperbolic correlation, whereas the pile material has been idealized as elastic–perfectly plastic. The effect of progressive pile-soil slippage at the interface is considered. Apart from predicting the load-displacement response with incremental angle of twist of pile under pure torsion, the profiles for shear stress and angle of twist and the depth of interface slippage are some of the salient features captured by the proposed model. Validation of the model developed by comparing with existing models and experimental data indicate the suitability and accuracy of the solutions developed. However, minor discrepancies in the solution appeared owing to the simplified assumptions of perfectly plastic postpeak soil behavior and the absence of residual stress in the soil owing to pile installation. The proposed model is also applied successfully to selected case studies on concrete piles (L/D ranged from 10–40) in medium-soft clay, medium-dense sand, and layered soil, and a set of design curves have been constructed.

Evaluation of the absorption line blackbody distribution function of CO2 and H2O using the proper orthogonal decomposition and hyperbolic correlations

Databases of the absorption line blackbody distribution function (ALBDF) of CO2 and H2O were generated over a wide range of gas and blackbody temperatures and the full range of gas concentration from line-by-line (LBL) calculations using the latest version of HITEMP. Proper orthogonal decomposition (POD) and the hyperbolic correlations (HC) were then used for rapid calculation the ALBDF value at an arbitrary combination of gas and blackbody temperatures and gas concentration. A novel hyperbolic correlation for H2O was proposed to fully account for the self-broadening effect. The accuracy of POD and the HC was evaluated by comparing the ALBDF values and the total gas emissivities from these two approximate methods at several selected conditions against those from LBL calculations. POD is significantly more accurate than HC at essentially no extra computational costs.

Hyperbolic correlation between insulin sensitivity and insulin secretion fades away in lean subjects with superb glucose regulation

The relationship between insulin sensitivity (Si) and insulin secretion (β) was analyzed in 533 health examinees. The subjects underwent a 75 g oral glucose tolerance test, with plasma glucose (PG) and immunoreactive insulin (IRI) determined at fasting, 30 min and 120 min, and were classified according to the current criteria as normal glucose tolerance (NGT, n=328), non-diabetic hyperglycemia (NDH, n=113) including impaired fasting glucose and impaired glucose tolerance, and diabetes mellitus (DM, n=72). NGT was subdivided by fasting PG (FPG) tertile, ≤4.9, 5.0-5.4 and 5.5-6.0 mM, into NGT(FPG1), NGT(FPG2) and NGT(FPG3), or by body mass index (BMI) tertile, ≤21.8, 21.9-24.4 and ≥24.5 kg/m², into NGT(BMI1), NGT(BMI2) and NGT(BMI3). As an index of Si and β, Matsuda index=10,000/sqrt[FPG·FIRI·2hPG·2hIRI] and δIRI₀₋₃₀/δPG₀₋₃₀, were employed respectively: FIRI, 2hPG and 2hIRI denote fasting IRI, 2h-post glucose PG and IRI, respectively. Correlation between Si and β was evaluated by Spearman's rank correlation and the parameters for [β]=a·[Si](b) were obtained by standardized major axis (SMA) regression. Si-β correlation was strongest in NDH (Spearman's rho=-0.546, SMA regression r²=0.277), intermediate in DM (rho=-0.432, r²=0.193) and weakest in NGT (rho=-0.201, r²=0.039). Spearman's rho for the Si-β correlation was significantly lower in NGT than in NDH (p=0.003). Si-β correlation was significant in NGT(FPG3), NGT(FPG2) and NGT(BMI3), but not in NGT(FPG1), NGT(BMI2) and NGT(BMI1). The slope, b, was -1.184˜-1.530 without significant differences between any groups. In conclusion, the hyperbolic Si-β correlation was weaker in NGT than in NDH and absent in NGT subjects belonging to the lowest FPG or BMI tertile.

Explorations of high-intensity therapeutic ultrasound and microbubble-mediated gene delivery in mouse liver

Ultrasound (US) combined with microbubbles (MBs) is a promising technology for non-viral gene delivery. Significant enhancements of gene expression have been obtained in our previous studies. To optimize and prepare for application to larger animal models, the luciferase reporter gene transfer efficacy of lipid-based Definity MBs of various concentrations, pressure amplitudes and a novel unfocused high-intensity therapeutic US (HITU) system were explored. Luciferase expression exhibited a dependence on MB dose over the range of 0-25 vol%, and a strong dependence on acoustic peak negative pressure at over the range of 0-3.2 MPa. Gene expression reached an apparent plateau at MB concentration ≥2.5 vol% or at negative pressures >1.8 MPa. Maximum gene expression in treated animals was 700-fold greater than in negative controls. Pulse train US exposure protocols produced an upward trend of gene expression with increasing quiescent time. The hyperbolic correlation of gene expression and transaminase levels suggested that an optimum gene delivery effect can be achieved by maximizing acoustic cavitation-induced enhancement of DNA uptake and minimizing unproductive tissue damage. This study validated the new HITU system equipped with an unfocused transducer with a larger footprint capable of scanning large tissue areas to effectively enhance gene transfer efficiencies.

High Strength Natural Fibers for Improved Polymer Matrix Composites

A statistical evaluation based on the Weibull method was performed to correlate the mechanical properties and the diameter of different lignocellulosic fibers. The sisal, rami and curaua fibers were found to have a hyperbolic correlation between their ultimate strength and diameter. This permitted to select thinner high strength fibers, with over 1000 MPa, as reinforcement for the strongest polymer composites ever fabricated with these fibers. A structural analysis was conducted by electron microscopy to identify the strengthening mechanism for both, the high performance fiber and their improved polymer composites.

Diameter dependence of tensile strength by Weibull analysis: Part III sisal fiber

Environmental aspects and economical advantages are motivating the use of natural fiber as reinforcement of polymer composites in substitution for synthetic fiber composites such as fiber glass. In particular, the sisal fiber is one of the most investigated and being used in engineering systems. By contrast to synthetic fibers, natural fibers have the disadvantage of being heterogeneous in their dimensions specially the diameter. In several natural fibers it has been found that the smaller the diameter, the stronger is the fiber. In this work a Weibull analysis of sisal fibers tensile strength was performed to find a correlation with the diameter. The results revealed an inverse dependence of the tensile strength with the diameter. The observation of ruptured fibers by scanning electron microscopy suggested possible mechanisms that justify a hyperbolic correlation.

In vivo PET studies in non-human primate model of neuropsychiatric disorders and neurodegenerative diseases: the differences between macaques and marmosets

We evaluated correlation between neurochemical and functional alterations of the nigrostriatal dopaminergic system in rat brains lesioned with 6-hydroxydopamine (6-OHDA), that model hemi-Parkinson's disease (PD), by using three different quantitative in vivo and in vitro methods. Rats unilaterally lesioned with different doses of 6-OHDA underwent two types of in vivo experiments: (1) a rotational behavioral study with methamphetamine (MAP) or apomorphine (APO); and (2) a positron emission tomography (PET) study with [11C]PE2I (radioligand for dopamine transporters) or [11C]raclopride (radioligand for dopamine D2 receptors). An in vitro autoradiographic study with the same radioligands was also conducted. The number of rotations after the MAP or APO injection increased with increased doses of 6-OHDA. The in vitro and in vivo binding of [11C]PE2I dose-dependently decreased in response to the 6-OHDA injections, while that of [11C]raclopride dose-dependently increased. There was a significant negative hyperbolic correlation between the number of rotations after MAP injection and the binding of [11C]PE2I. In contrast, there was a significant positive linear correlation between the number of rotations after APO injections and the binding of [11C]raclopride. These results robustly reveal a molecular pharmacological basis of parkinsonian symptoms in animal models of PD, and indicate the utility and validity of in vivo PET measurements in assessing pre- and post-synaptic dopaminergic functions.

Left ventricular size determines tissue Doppler-derived longitudinal strain and strain rate

Tissue Doppler-derived indices of strain (epsilon) and strain rate (SR) have been developed to assess regional cardiac function. However, the effect of left ventricular (LV) size on epsilon and SR has not been studied in depth. The aim of this study was to assess to what extent heart size influence epsilon or SR. In 21 anaesthetized pigs ranging from 12.5 to 70.0 kg, tissue Doppler-derived epsilon and SR, and haemodynamic parameters, were assessed during controlled heart rates and different loading conditions. dP/dt did not correlate to pig weight, suggesting constant contractility during growth. Longitudinal epsilon and SR were significantly higher in smaller compared with larger hearts. The hyperbolic correlation between pigs weight and epsilon and SR was r(2)=0.621 and 0.372, respectively, both P<0.0001. Afterload elevation induced a reduction in longitudinal epsilon (from -24.2+/-3.2 to -12.1+/-5.5%, P=0.001) and SR (from -2.3+/-0.8 to -1.3+/-2.4 s(-1), P=0.034), whereas increasing preload increased epsilon (from -26.4+/-10.3 to -38.1+/-14.3%, P=0.006) and SR (from -2.3+/-0.9 to -4.22+/-1.8 s(-1), P=0.002). Longitudinal epsilon and SR decrease with increasing LV dimensions in spite of an unaltered contractility. These results show and confirm that heart size influences epsilon and SR, which are highly load-dependent parameters.

Urinary Crystallization Index: A risk marker for Calcium Oxalate Lithiasis

PURPOSE To determine the value of Bonn Risk Index (BRI) in Calcium Oxalate stone formers before and after stone removal. MATERIAL AND METHODS Twenty four hours urinary and stat urine samples were collected from 66 patients with Calcium Oxalate stones before and one month after stone removal with dietary and medical interventions. BRI was estimated in 2 ml of native urine at 37 °C. Ammonium Oxalate 40 mmol/L was added at minute interval with constant mixing in 0.050 ml increments and absorbance measured at 620λ in spectrophotometer. Nucleation was recorded with the increase of absorbance. Ionic Calcium was measured by an Ion selective electrode. BRI was calculated by the formula: BRI = [Ca + 2] mmol/L/ [Ox-2]. BRI > 1/L was taken as risk and BRI of < 1/L as low to no risk for stone formation. Urinary calcium, magnesium, oxalate, citrate, sodium, potassium, phosphate and pH were recorded in all samples. RESULTS The mean BRI before surgery in 24 hour urine was 3.4 ± 1.8/L as compared to post-operative mean value of BRI 1.4 ± 1.4/L (p = 0.002). Mean urinary calcium before surgery was 1.8 ± 0.6 mmol/L vs 1.2 ± 0.4 (p = 0.01) after surgery. Mean oxalate added was 0.8 ± 0.3 vs 1.3 ± 0.5 mmol after surgery. Urinary magnesium showed a hyperbolic correlation with BRI. No correlation was found with citrate. In comparison to 24 hour urine the mean BRI in 14 stat samples was 4.6 ± 5.29 vs 2.1 ± 1.8 in stat urine post-operative. CONCLUSIONS BRI is a valuable tool to assess risk of Calcium Oxalate stone formation and clearly reflects the influence of dietary and medical intervention post operatively. It can be used to monitor effects of dietary and medical interventions.

Awaking TIM22, a Dynamic Ligand-gated Channel for Protein Insertion in the Mitochondrial Inner Membrane

Aqueous channels are at the core of the translocase of the outer membrane (TOM) and the translocase of the inner membrane for the transport of preproteins (TIM23), the translocases mediating the transport of proteins across the outer and inner mitochondrial membranes. Yet, the existence of a channel associated to the translocase of the inner membrane for the insertion of multitopic protein (TIM22) complex has been arguable, as its function relates to the insertion of multispanning proteins into the inner membrane. For the first time, we report conditions for detecting a channel activity associated to the TIM22 translocase in organelle, i.e. intact mitoplasts. An internal signal peptide in the intermembrane space of mitochondria is a requisite to inducing this channel, which is otherwise silent. The channel showed slightly cationic and high conductance activity of 1000 pS with a predominant half-open substate. Despite their different composition, the channels of the three mitochondrial translocases were thus remarkably similar, in agreement with their common task as pores transiently trapping proteins en route to their final destination. The opening of the TIM22 channel was a step-up process depending on the signal peptide concentration. Interestingly, low membrane potentials kept the channel fully open, providing a threshold level of the peptide is present. Our results portray TIM22 as a dynamic channel solely active in the presence of its cargo proteins. In its fully open conformation, favored by the combined action of internal signal peptide and low membrane potential, the channel could embrace the in-transit protein. As insertion progressed and initial interaction with the signal peptide faded, the channel would close, sustaining its role as a shunt that places trapped proteins into the membrane.

Correlation between quantitative imaging and behavior in unilaterally 6-OHDA-lesioned rats

We evaluated correlation between neurochemical and functional alterations of the nigrostriatal dopaminergic system in rat brains lesioned with 6-hydroxydopamine (6-OHDA), that model hemi-Parkinson's disease (PD), by using three different quantitative in vivo and in vitro methods. Rats unilaterally lesioned with different doses of 6-OHDA underwent two types of in vivo experiments: (1) a rotational behavioral study with methamphetamine (MAP) or apomorphine (APO); and (2) a positron emission tomography (PET) study with [ 11C]PE2I (radioligand for dopamine transporters) or [ 11C]raclopride (radioligand for dopamine D2 receptors). An in vitro autoradiographic study with the same radioligands was also conducted. The number of rotations after the MAP or APO injection increased with increased doses of 6-OHDA. The in vitro and in vivo binding of [ 11C]PE2I dose-dependently decreased in response to the 6-OHDA injections, while that of [ 11C]raclopride dose-dependently increased. There was a significant negative hyperbolic correlation between the number of rotations after MAP injection and the binding of [ 11C]PE2I. In contrast, there was a significant positive linear correlation between the number of rotations after APO injections and the binding of [ 11C]raclopride. These results robustly reveal a molecular pharmacological basis of parkinsonian symptoms in animal models of PD, and indicate the utility and validity of in vivo PET measurements in assessing pre- and post-synaptic dopaminergic functions.

A High Calcium-Phosphate Product Is Associated with High C-Reactive Protein Concentrations in Hemodialysis Patients

Background: An elevated Ca×PO₄ product and C-reactive protein (CRP) have been associated with coronary artery calcification and increased cardiovascular mortality in hemodialysis (HD) patients. However, it has not been defined, so far, whether and how both parameters are related to each other. For this reason we have evaluated in a cross-sectional and in an interventional study the possible correlation between Ca×PO₄ and CRP and the effect of the correction of a high Ca×PO₄ on CRP levels. Methods: 47 uremic patients (age 65 ± 16 years) on regular chronic HD were selected from a total population of 125 prevalent patients treated at our Institution. Patients had no clinical evidence of either acute infectious or inflammatory diseases for at least 4 weeks before the study. They were on regular bicarbonate HD for 6–329 months (median 42). CRP, hemoglobin (Hb), serum albumin (sAlb), protein catabolic rate (PCRn), serum calcium (Ca), serum phosphorus (PO₄), Ca×PO₄, intact PTH, Kt/V, presence of ischemic heart disease (IHD) and/or peripheral vascular disease (PVD) were recorded. CRP was Ln-transformed in all statistical analyses because of positive skewness. Results: The main findings were: LnCRP 2.17 ± 0.77 mg/l, Ca 10.1 ± 0.4 mg/dl, PO₄ 5.8 ± 0.6 mg/dl, Ca×PO₄ 59 ± 6 mg²/dl², andPTHint 218 ± 195 ng/ml. 18/47 had IHD, 18/47 PVD. A significant hyperbolic correlation between Ca×PO₄ and CRP was observed. A piecewise linear regression model analysis identified a break-point for Ca×PO₄ at 55 mg²/dl². Comparison of CRP levels after the division of the patients into two groups according to Ca×PO₄ break-point (group A, Ca×PO₄ ≤55 mg²/dl², n = 16 patients; group B, Ca×PO₄ >55 mg²/dl², n = 31 patients) showed that CRP levels were significantly lower in patients in group A (LnCRP 1.43 ± 0.22 mg/l) than in group B (LnCRP 2.55 ± 0.67 mg/l, p < 0.0001). Multiple regression analysis bearing LnCRP as dependent variable confirmed Ca×PO₄ as the most significant variable among the other variables examined. In 22 patients with Ca×PO₄ ≧60 mg²/dl², we performed intensive lowering of the Ca×PO₄ product in order to reach and maintain a Ca×PO₄ ≤55 mg²/dl² for 3 months. At the end of observation, a significant reduction in Ca×PO₄ and LnCRP was observed (Ca×PO₄ pre 62.8 ± 1.9 vs. post 46.3 ± 6.2 mg²/dl²: p < 0.0001; LnCRP pre 2.32 ± 0.36 vs. post 1.83 ± 0.14 mg/l: p < 0.0001). No significant variation in the other biochemical parameters was observed. Conclusions: Our data show that in chronic HD patients in steady clinical conditions with no clinical evidence of either infectious or inflammatory diseases, a high Ca×PO₄ is associated with high CRP concentrations. Intensive lowering of Ca×PO₄ reduces CRP.