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PubMed2001

Demonstrating attainment of the air quality standards: integration of observations and model predictions into the probabilistic framework.

This paper introduces an integrated observational-modeling approach to transform the deterministic nature of attainment demonstrations of the National Ambient Air Quality Standard (NAAQS) into the probabilistic framework. While the methods presented here can be used to address any air quality standard that is based on extreme values, this paper focuses on the application to the 1-hr and 8-hr NAAQS for ozone. Extreme value statistics and resampling techniques are applied to estimate the probability of exceeding the NAAQS for both 1-hr and 8-hr ozone concentrations. Within the integrated observation-modeling analysis approach, we show that the model-to-model differences in the predicted responses to emission reductions are smaller than the model-to-model differences in predicted absolute ozone concentrations. We illustrate that the emission reductions stemming from a real-world emission control strategy would substantially reduce the probability of exceeding the NAAQS over a large portion of the eastern United States, especially for the 8-hr average ozone concentrations.

Air Pollution↗
PubMed1999

Stabilization and reactivation of the p53 tumor suppressor protein in nontumorigenic revertants of HeLa cervical cancer cells.

We demonstrated previously that loss of in vitro transformation and in vivo tumorigenicity in two independent revertant clones of HeLa cells (designated HA and HF) resulted from dominant-acting genetic changes. Analysis of the p53 tumor suppressor gene revealed stabilization and at least partial restoration of wild-type p53 transactivation properties pathways in both revertants of HPV-induced cell transformation. The half-lives of the p53 protein and both of the HA and HF clones were increased approximately 4 fold compared with the parental HeLa cells (16, 17, and 4 min, respectively). The levels of E6 viral protein expression were similar in the three cell lines, whereas the levels of the ubiquitin ligase protein, E6 associated protein (E6-AP), were elevated in the revertants. Western blot analysis of immunoaffinity-purified p53 demonstrated that stabilization of p53 in the revertants was correlated with a reduction in the in vivo formation of complexes involving the E6 oncoprotein and p53. Stabilization of p53 function in the revertants did not result from mutations in either the p53 or E6-AP genes. Despite the observed stabilization and restoration of p53 transactivation function in the revertants, exposure of the revertants to DNA-damaging agents did not result in elevated levels of p21(waf-1) protein and failed to induce growth arrest in the G1 phase of the cell cycle. However, p53-independent induction of p21(waf-1) protein also failed to induce the G1 phase of the cell cycle. Thus, restoration of wild-type p53 transactivation activity in the HA and HF revertants is insufficient to induce G1 arrest and reversion from HPV-induced cell transformation in our model system.

Cell Division↗
PubMed1981

Temperature-sensitive mutants of Fujinami sarcoma virus: tumorigenicity and reversible phosphorylation of the transforming p140 protein.

Several clones of Fujinami sarcoma virus (FSV) isolated from a laboratory stock or from mutagenized virus were temperature sensitive (ts) in transformation of cells in culture. When shifted from the permissive (37 degrees C) to the nonpermissive (41.5 degrees C) temperature, the cellular phenotype reverted to normal within 2 h, but it required about 48 h at 37 degrees C to revert back to the transformed morphology. A temperature-resistant (tr) FSV clone was isolated from a tumor of an animal. All ts mutants were tumorigenic in animals but induced tumors only after latent periods of 12 to 25 days, compared to 5 to 6 days with tr virus. The ts lesions of the FSV mutants affected 90% of the phosphorylation of the nonstructural, gag-related 140,000-kilodalton phosphoprotein coded by FSV (p140), but did not affect virus replication or the synthesis of p140. Upon shifting from the permissive to the nonpermissive temperature, p140 was 90% dephosphorylated with an approximate (32)P half-life of 20 min. When shifted back to the permissive temperature, the preexisting p140 was rephosphorylated in the absence of protein synthesis within a 90-min test period. Likewise, most of the phosphate of fully phosphorylated p140 was exchanged at the permissive temperature within 30 to 90 min even when protein synthesis was inhibited. However, the protein structure of p140 had a half-life of 5 h at both temperatures. These results prove p140 to be a substrate of reversible phosphorylation. Superinfection and transformation of ts FSV-infected cells maintained at the nonpermissive temperature with acute leukemia virus MC29 failed to phosphorylate p140. It would follow that in vivo phosphorylation of ts p140 is controlled by an FSV-specific mechanism and is a prerequisite, not a consequence, of transformation. p140 of ts FSV recovered from cells maintained at 41.5 degrees C with anti-gag serum was over 10 times less phosphorylated by associated kinase than the same protein recovered from cells at 37 degrees C if assayed in vitro at 20 degrees C. This kinase activity associated with or dissociated from p140 with a half-life of less than 30 min during temperature shifts of ts FSV-infected cells. However, p140 recovered from ts FSV-infected cells maintained at 37 degrees C was phosphorylated by associated kinase in vitro not only at 20 degrees C but also, and essentially at the same level, at 41.5 degrees C. This suggests that the kinase associated with the immunocomplex of p140 of ts FSV is not temperature sensitive. p140 translated in vitro from ts and tr FSV RNA lacked kinase activity. We conclude that a fully phosphorylated p140 is necessary for the maintenance of transformation by FSV. This is consistent with the notion that other highly oncogenic viruses also code for nonstructural phosphoproteins with probable transforming function. A model which postulates that p140 is a substrate of reversible phosphorylation and that the lesion of the ts FSV clones described herein affects association of p140 with a cellular kinase rather than a hypothetical intrinsic kinase activity of the protein is most compatible with our data.

Alpharetrovirus↗
PubMed1986

A biophysical model of cochlear processing: intensity dependence of pure tone responses.

A mathematical model of cochlear processing is developed to account for the nonlinear dependence of frequency selectivity on intensity in inner hair cell and auditory nerve fiber responses. The model describes the transformation from acoustic stimulus to intracellular hair cell potentials in the cochlea. It incorporates a linear formulation of basilar membrane mechanics and subtectorial fluid-cilia displacement coupling, and a simplified description of the inner hair cell nonlinear transduction process. The analysis at this stage is restricted to low-frequency single tones. The computed responses to single tone inputs exhibit the experimentally observed nonlinear effects of increasing intensity such as the increase in the bandwidth of frequency selectivity and the downward shift of the best frequency. In the model, the first effect is primarily due to the saturating effect of the hair cell nonlinearity. The second results from the combined effects of both the nonlinearity and of the inner hair cell low-pass transfer function. In contrast to these shifts along the frequency axis, the model does not exhibit intensity dependent shifts of the spatial location along the cochlea of the peak response for a given single tone. The observed shifts therefore do not contradict an intensity invariant tonotopic code.

Acoustic Stimulation↗
PubMed2026

Prevalence of Claudin 18.2 Expression in Gastric and Gastroesophageal Junction Adenocarcinoma: A Systematic Review and Meta-Analysis.

BACKGROUND: Claudin 18 isoform 2 (CLDN18.2) has emerged as a clinically validated therapeutic target in gastric and gastroesophageal junction (GEJ) adenocarcinoma following the regulatory approval of zolbetuximab in combination with first-line chemotherapy. Accurate prevalence data at the clinically validated immunohistochemical threshold are essential for patient selection, healthcare resource planning, and treatment strategy. Reported prevalence estimates vary widely across studies due to differences in populations, methodologies, and immunohistochemical protocols. This systematic review and meta-analysis aimed to generate a robust pooled prevalence estimate of CLDN18.2 expression at the threshold used in pivotal phase III trials. METHODS: PubMed, Embase, and the Cochrane Library were searched from database inception through March 12th, 2026. Studies reporting CLDN18.2 expression in gastric or gastroesophageal junction adenocarcinoma using the ≥ 75% moderate-to-strong membranous staining threshold were included. Prevalence proportions were pooled using a random-effects model with logit transformation and restricted maximum-likelihood estimation of between-study variance. Heterogeneity was assessed using the I² statistic and Cochran's Q test, and a 95% prediction interval was calculated. Pre-specified subgroup analyses assessed antibody clone and geographic region, with additional exploratory analyses according to disease setting and specimen type. Sensitivity analyses were performed to assess the robustness of the pooled estimate. RESULTS: Twenty-two predominantly retrospective cohort studies comprising 12,173 patients were included. The pooled prevalence of CLDN18.2 positivity using a random-effects model was 33.99% (95% CI: 30.13%-38.07%; 95% prediction interval: approximately 18%-55%), with high between-study heterogeneity (I² = 92.4%). Subgroup analysis by antibody clone showed no statistically significant difference between studies using the 43-14 A clone (32.79%, 95% CI: 28.86%-36.97%) and those using other reported antibody clones (41.74%, 95% CI: 26.76%-58.42%; p = 0.281). One study with an unreported antibody clone was excluded from this subgroup analysis. Geographic subgroup analysis excluding the multinational Shitara et al. cohort demonstrated a non-significant trend toward higher prevalence in non-Asian populations (37.85%, 95% CI: 31.59%-44.54%) compared with Asian populations (32.10%, 95% CI: 27.28%-37.34%; p = 0.169). All three sensitivity analyses confirmed robustness of the pooled estimate. No significant evidence of publication bias was detected (Egger's test p = 0.56). CONCLUSIONS: Approximately one-third of patients with gastric and GEJ adenocarcinoma express CLDN18.2 at the clinically validated ≥ 75% threshold. However, because the included studies encompassed heterogeneous disease settings and were predominantly HER2-unselected, the pooled estimate should not be interpreted directly as the proportion of patients eligible for zolbetuximab. The estimate was robust across sensitivity analyses and provides an evidence base for understanding CLDN18.2 prevalence and biomarker-testing requirements. Standardisation of immunohistochemical assessment methods is warranted to reduce between-study heterogeneity in future research.

Humans↗
PubMed2004

Realistic protein-protein association rates from a simple diffusional model neglecting long-range interactions, free energy barriers, and landscape ruggedness.

We develop a simple but rigorous model of protein-protein association kinetics based on diffusional association on free energy landscapes obtained by sampling configurations within and surrounding the native complex binding funnels. Guided by results obtained on exactly solvable model problems, we transform the problem of diffusion in a potential into free diffusion in the presence of an absorbing zone spanning the entrance to the binding funnel. The free diffusion problem is solved using a recently derived analytic expression for the rate of association of asymmetrically oriented molecules. Despite the required high steric specificity and the absence of long-range attractive interactions, the computed rates are typically on the order of 10(4)-10(6) M(-1) sec(-1), several orders of magnitude higher than rates obtained using a purely probabilistic model in which the association rate for free diffusion of uniformly reactive molecules is multiplied by the probability of a correct alignment of the two partners in a random collision. As the association rates of many protein-protein complexes are also in the 10(5)-10(6) M(-1) sec(-1) range, our results suggest that free energy barriers arising from desolvation and/or side-chain freezing during complex formation or increased ruggedness within the binding funnel, which are completely neglected in our simple diffusional model, do not contribute significantly to the dynamics of protein-protein association. The transparent physical interpretation of our approach that computes association rates directly from the size and geometry of protein-protein binding funnels makes it a useful complement to Brownian dynamics simulations.

Computer Simulation↗
PubMed2004

Advanced statistics: linear regression, part II: multiple linear regression.

The applications of simple linear regression in medical research are limited, because in most situations, there are multiple relevant predictor variables. Univariate statistical techniques such as simple linear regression use a single predictor variable, and they often may be mathematically correct but clinically misleading. Multiple linear regression is a mathematical technique used to model the relationship between multiple independent predictor variables and a single dependent outcome variable. It is used in medical research to model observational data, as well as in diagnostic and therapeutic studies in which the outcome is dependent on more than one factor. Although the technique generally is limited to data that can be expressed with a linear function, it benefits from a well-developed mathematical framework that yields unique solutions and exact confidence intervals for regression coefficients. Building on Part I of this series, this article acquaints the reader with some of the important concepts in multiple regression analysis. These include multicollinearity, interaction effects, and an expansion of the discussion of inference testing, leverage, and variable transformations to multivariate models. Examples from the first article in this series are expanded on using a primarily graphic, rather than mathematical, approach. The importance of the relationships among the predictor variables and the dependence of the multivariate model coefficients on the choice of these variables are stressed. Finally, concepts in regression model building are discussed.

Bias↗
PubMed2002

[Effects of soy extract on energy balance in ovariectomized rats].

OBJECTIVE: In order to study on effects of soy extract on energy metabolims in ovariectomized rats. METHOD: 90 Wistar rats were randomly divided into 9 groups: control group, sham group, model group, estrogen group, soy isoflavone group of high dose, soy isoflavone of low dose, soy extract of high dose, soy extract of low dose, 10 rats each group. Beside of control and sham groups, the rest rats were ovariectomized. One week after operation, the rats were treatmented with different drugs, measument of body weigh and feed weigh each week. Six week after operation, the rats were killed, serum were taken, abdomen lipid were removed and weight. RESULT: The ovariectomized rats took more food and got weight gain significantly; Body mess index(BMI), Abdomen lipid weigh and food transform rate in Model group increased significantly than control and sham groups. Administration of estrogen or soy extract or soy isoflavone could block these changes in ovariectomized rats, but soy polysaccharides did not have the effects. CONCLUSION: Ovariectomized rats have imbalance of energy metabolism, weigh gain and accumulation of abdomen lipid; administration of estrogen, soy extracts or soy isoflavone could attenuate these changes induced by ovariectomizing.

Animals↗
PubMed1995

Astrocytes derived from p53-deficient mice provide a multistep in vitro model for development of malignant gliomas.

Loss or mutation of p53 is thought to be an early event in the malignant transformation of many human astrocytic tumors. To better understand the role of p53 in their growth and transformation, we developed a model employing cultured neonatal astrocytes derived from mice deficient in one (p53 +/-) or both (p53 -/-) p53 alleles, comparing them with wild-type (p53 +/+) cells. Studies of in vitro and in vivo growth and transformation were performed, and flow cytometry and karyotyping were used to correlate changes in growth with genomic instability. Early-passage (EP) p53 -/- astrocytes achieved higher saturation densities and had more rapid growth than EP p53 +/- and +/+ cells. The EP p53 -/- cells were not transformed, as they were unable to grow in serum-free medium or in nude mice. With continued passaging, p53 -/- cells exhibited a multistep progression to a transformed phenotype. Late-passage p53 -/- cells achieved saturation densities 50 times higher than those of p53 +/+ cells and formed large, well-vascularized tumors in nude mice. p53 +/- astrocytes exhibited early loss of the remaining wild-type p53 allele and then evolved in a manner phenotypically similar to p53 -/- astrocytes. In marked contrast, astrocytes retaining both wild-type p53 alleles never exhibited a transformed phenotype and usually senesced after 7 to 10 passages. Dramatic alterations in ploidy and karyotype occurred and were restricted to cells deficient in wild-type p53 following repeated passaging. The results of these studies suggest that loss of wild-type p53 function promotes genomic instability, accelerated growth, and malignant transformation in astrocytes.

Animals↗
PubMed1997

Suppression of malignant phenotype of a transformed mouse mammary epithelial cell line (11A1) by tumor suppressor gene RB.

A malignant transformed mammary epithelial cell line (11A1) was transfected with liposome encapsulated eukaryotic expression plasmid pCMV-neo-RB, yielding 4 constant clones which have obvious phenotypic reversion changes, and named 11A1-R1-R4 respectively. Further experiments showed that the 11A1-R1 behaved like normal epithelial cells in both morphological and biological characteristics, with decreased clonogenicity in solid argar medium as well as decreased tumorigenicity. Northern blot hybridization showed increased expression of RB gene and decreased expression of c-myc gene in 11A1-R1, 11A1-R2 cells compared to 11A1 cells. This was an ideal phenotypic reversion model for epithelial transformed cell line and demonstrated that the RB gene can reexpress and suppress malignant phenotype in RB inactive cells.

Animals↗
PubMed1988

Coordinates transformation and learning control for visually-guided voluntary movement with iteration: a Newton-like method in a function space.

In order to control visually-guided voluntary movements, the central nervous system (CNS) must solve the following three computational problems at different levels: (1) determination of a desired trajectory in the visual coordinates, (2) transformation of the coordinates of the desired trajectory to the body coordinates and (3) generation of motor command. In this paper, the second and the third problems are treated at computational, representational and hardware levels of Marr. We first study the problems at the computational level, and then propose an iterative learning scheme as a possible algorithm. This is a trial and error type learning such as repetitive training of golf swing. The amount of motor command needed to coordinate activities of many muscles is not determined at once, but in a step-wise, trial and error fashion in the course of a set of repetitions. Actually, the motor command in the (n + 1)-th iteration is a sum of the motor command in the n-th iteration plus two modification terms which are, respectively, proportional to acceleration and speed errors between the desired trajectory and the realized trajectory in the n-th iteration. We mathematically formulate this iterative learning control as a Newton-like method in functional spaces and prove its convergence under appropriate mathematical conditions with use of dynamical system theory and functional analysis. Computer simulations of this iterative learning control of a robotic manipulator in the body or visual coordinates are shown. Finally, we propose that areas 2, 5, and 7 of the sensory association cortex are possible sites of this learning control. Further we propose neural network model which acquires transformation matrices from acceleration or velocity to motor command, which are used in these schemes.

Central Nervous System↗
PubMed1992

Cell surface oligosaccharide modulation during differentiation: VI. The effect of biomodulation on the senescent and neoplastic cell phenotype.

These investigations test the hypothesis developed previously, that there are biomolecules which control and integrate cellular differentiation. Our specific interest in cellular differentiation lies in the area of what we refer to as basal or primitive cellular differentiation mechanisms. These mechanisms are common to all cells, and are required for simple recognition and growth regulation. We have investigated two models, the IMR-90 human fetal lung fibroblast model as a representative of normal growth control, and the CG model, canine glioma cells, a transplantable growth transformed cell line. These two models represent normal, and aberrant cellular differentiation control. In previous studies we have shown that the arrangement of the cell surface oligosaccharide structure on these cell types are predictive of phenotypic transition. We have developed, and partially characterized a series of BIOMODULATORS (BM) which delay the onset of display of neoplastic cells. Three classes of BIOMODULATOR have been explored; (1) a large molecular weight natural product (25-35 kDa), PokeWeed Mitogen (PWM); (2) a small molecular weight natural product (500 Da) Cellular Activator and Differentiator (CAD) and a number of natural and synthetic analogs; and (3) an indolizidine alkaloid natural product, Swainsonine (Sw) which has a known cellular target (oligosaccharide biosynthesis). Preliminary data is presented which structurally links some of these BIOMODULATORS in terms of their effective stereochemistry. These BIOMODULATORS, when used before PDL 38, prevent the cell surface oligosaccharide display changes typical of morphological senescence and delay their onset to PDL 100 or more. These BIOMODULATORS also appear to have regulatory effects on the neoplastic cell models. This re-regulation results in increases in generation time and an increase in the ability of these cells to be recognized by cytotoxic lymphocytes. Proton NMR linewidth measurements of the fraction of 'bound' water associated with the cellular surface of treated and untreated cell populations showed induced physical changes in the cell surface related to the use of the BIOMODULATOR and correlated to the oligosaccharide display changes. These data were interpreted as indicating an increase in the organizational level of these cells. The data for normal and neoplastic cell populations are compared and contrasted in an effort to form the basis for an analytical approach to the control and integration of differentiation mechanisms.

Animals↗
PubMed2005

[Preclinical models of prostate cancer].

Although prostate cancer is a major cause of cancer death and morbidity in Western countries, one major hindrance in the study of the biology of prostate cancer has been the limited number of laboratory models, compared with the number of models available for other neoplasms. For a long time, only three cell lines, namely LNCaP, PC3, and DU145, were routinely used to study prostate cancer in the lab. The success rate to establish cell lines from human prostate cancer tissues is low, in the 1% range. Currently, only about 10 prostate cancer cell lines are available, and many of them do not reproduce typical features of the human disease, like androgen receptor expression or prostate specific antigen (PSA) secretion. Spontaneous models in animals (including rat and dog) are practically not convenient for research purposes. Several in vivo models were artificially established by transforming prostate cells by potent oncogenes. Other models were developed by injecting prostate cancer cell lines into the prostate (orthotopic model), the vessel, or the bones of immuno-deficient mice, to mimic localized and metastatic prostate cancer. This was successfully done with the MDA PCa2b cell line. This cell line was also used to generate an in vitro model of bone metastases by a co-culture system with osteoblasts. This model allows to study the paracrine cross-talk between the two cell compartments and the resulting molecular modifications. The objective of the present article is to review the currently available model systems of prostate cancer.

Animals↗
PubMed1996

[The prognostic criteria in the primary myelodysplastic syndrome].

Basing on computer processing of 126 primary clinical and laboratory parameters obtained from 92 patients with myelodysplasia and using multifactorial regression analysis, the authors have developed prognostic models of life span and probability of transformation into acute leukemia. The model of life span enabled recognition of 3 prognostic groups of myelodysplasia patients: of high (median 10 months), moderate (median 22 months) and low (median 35 months) risk. This makes it possible to prognosticate the disease and assume optimal therapeutic policy.

Adult↗
PubMed2003

Mechanism of proton transport in bacteriorhodopsin from crystallographic structures of the K, L, M1, M2, and M2' intermediates of the photocycle.

We produced the L intermediate of the photocycle in a bacteriorhodopsin crystal in photo-stationary state at 170 K with red laser illumination at 60% occupancy, and determined its structure to 1.62 A resolution. With this model, high-resolution structural information is available for the initial bacteriorhodopsin, as well as the first five states in the transport cycle. These states involve photo-isomerization of the retinal and its initial configurational changes, deprotonation of the retinal Schiff base and the coupled release of a proton to the extracellular membrane surface, and the switch event that allows reprotonation of the Schiff base from the cytoplasmic side. The six structural models describe the transformations of the retinal and its interaction with water 402, Asp85, and Asp212 in atomic detail, as well as the displacements of functional residues farther from the Schiff base. The changes provide rationales for how relaxation of the distorted retinal causes movements of water and protein atoms that result in vectorial proton transfers to and from the Schiff base.

Bacteriorhodopsins↗
PubMed2001

Color line search for illuminant estimation in real-world scenes.

The estimation of illuminant color is mandatory for many applications in the field of color image quantification. However, it is an unresolved problem if no additional heuristics or restrictive assumptions apply. Assuming uniformly colored and roundly shaped objects, Lee has presented a theory and a method for computing the scene-illuminant chromaticity from specular highlights [H. C. Lee, J. Opt. Soc. Am. A 3, 1694 (1986)]. However, Lee's method, called image path search, is less robust to noise and is limited in the handling of microtextured surfaces. We introduce a novel approach to estimate the color of a single illuminant for noisy and microtextured images, which frequently occur in real-world scenes. Using dichromatic regions of different colored surfaces, our approach, named color line search, reverses Lee's strategy of image path search. Reliable color lines are determined directly in the domain of the color diagrams by three steps. First, regions of interest are automatically detected around specular highlights, and local color diagrams are computed. Second, color lines are determined according to the dichromatic reflection model by Hough transform of the color diagrams. Third, a consistency check is applied by a corresponding path search in the image domain. Our method is evaluated on 40 natural images of fruit and vegetables. In comparison with those of Lee's method, accuracy and stability are substantially improved. In addition, the color line search approach can easily be extended to scenes of objects with macrotextured surfaces.

Algorithms↗
PubMed2000

Implementing a new model of integrated women's health in academic health centers: lessons learned from the National Centers of Excellence in Women's Health.

The National Centers of Excellence in Women's Health Program (CoE) represents a new model for women's health in academic health centers that unites women's health research, teaching, clinical care, public education and outreach, and career advancement for women in the health sciences. Lessons learned from the first 3 years of implementation indicate that this type of model requires a transformation from the traditionally fragmented set of activities in academic health centers to an integrated system united around the goal of advancing women's health. The transformation requires institutional commitment, dedicated players, and an ability to build on existing resources and bring added value to the institution. Challenges and strategies to link women's health activities and increase collaboration are also discussed.

Academic Medical Centers↗
PubMed1998

Estimation of blood pressure variability from 24-hour ambulatory finger blood pressure.

Portapres is a noninvasive, beat-to-beat finger blood pressure (BP) monitor that has been shown to accurately estimate 24-hour intra-arterial BP at normal and high BPs. However, no information is available on the ability of this device to accurately track ambulatory BP variability. In 20 ambulatory normotensive and hypertensive subjects, we measured 24-hour BP by Portapres and through a brachial artery catheter. BP and pulse interval variabilities were quantified by (1) the SDs of the mean values (overall variability) and (2) spectral power, computed either by fast Fourier transform and autoregressive modeling of segments of 120-second duration for spectral components from 0.025 to 0.50 Hz or in a very low frequency range (between 0.00003 and 0.01 Hz) by broadband spectral analysis. The 24-hour SD of systolic BP obtained from Portapres (24+/-2 mm Hg) was greater than that obtained intra-arterially (17+/-1 mm Hg, P<0.01), but the overestimation was less evident for diastolic (3+/-1 mm Hg, P<0.01) and mean (3+/-1 mm Hg, P<0.01) BP. The BP spectral power <0.15 Hz was also overestimated by Portapres more for systolic than for diastolic and mean BPs; similar findings were obtained by the fast Fourier transform, the autoregressive approach, and focusing on the broadband spectral analysis. BP spectral power >0.15 Hz obtained by the Portapres was similar during the day but lower during the night when compared with those obtained by intra-arterial recordings (P<0.01). No differences were observed between Portapres and intra-arterial recordings for any estimation of pulse interval variabilities. The overestimation of BP variability by Portapres remained constant over virtually the entire 24-hour recording period. Thus, although clinical studies are still needed to demonstrate the clinical relevance of finger BP variability, our study shows that Portapres can be used with little error to estimate 24-hour BP variabilities if diastolic and mean BPs are used. For systolic BP, the greater error can be minimized by using correction factors.

Adult↗