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MONITORING INTRAVENOUS-INFUSION AND THE VENOUS CIRCULATION

ANESTHESIOLOGY CLINICS OF NORTH AMERICA 1988年第4期6卷 865-889页

作者： PHILIP, JH [*]Department of Anesthesia Brigham and Women’s Hospital Boston Massachusetts [**]Harvard Medical School and Harvard-MIT Division of Health Sciences and Technology Boston Massachusetts

This is an exciting time for IV therapy. Use of the IV route of administration continues to increase as patient acuity in today’s hospitals increases. IV therapy is not without risks, however, and a fuller understanding of the physical principles employed could help clinicians to reduce the incidence and severity of injuries resulting from drug extravasation (that is, tissue infiltration) and separate this dangerous phenomenon from less serious partial vein *** article summarizes a new conceptual model that can be demonstrated and used by making simple measurements during IV therapy. The model and technique employ an infusion pump that measures pressure, allowing the user to manually calculate resistance to fluid flow. Observing a rise in resistance at the IV site is an early indicator of undesirable changes at the catheter tip (that is, drug extravasation, catheter infiltration), even before the effect of these changes is visible or palpable on inspection of the IV *** insights obtained from the model, we observe that a properly used pressure-monitoring pump can detect resistance and obstruction to flow and differentiate between them. Also, it appears that suboptimal location of the catheter tip can be detected, and CVP can sometimes be measured from a peripheral IV *** for “instrument-assisted IV site monitoring” are (1) a flow source (IV pump), (2) a pressure monitoring system (transducer with pressure readout), and (3) the ability to analyze the PFR. This can be done most simply by measuring pressure at two or more flow rates and calculating P0 and R, the intercept and slope of the pressure versus flow graph. PFR analysis (computing R and P0) is subject to electronic software programming and could easily be added to the software of existing pressure-monitoring infusion instruments to provide intermittent IV site evaluation. If R and P0 monitoring were performed continuously and automatically, infiltration and obstruction could b

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Transcriptional network classifiers

Transcriptional network classifiers

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作者： Chang, Hsun-Hsien Ramoni, Marco F. Childrens' Hospital Informatics Program Harvard-MIT Division of Health Sciences and Technology Harvard Medical School Boston Massachusetts United States

Background: Gene interactions play a central role in transcriptional networks. Many studies have performed genome-wide expression analysis to reconstruct regulatory networks to investigate disease processes. Since biological processes are outcomes of regulatory gene interactions, this paper develops a system biology approach to infer function-dependent transcriptional networks modulating phenotypic traits, which serve as a classifier to identify tissue states. Due to gene interactions taken into account in the analysis, we can achieve higher classification accuracy than existing methods. Results: Our system biology approach is carried out by the Bayesian networks framework. The algorithm consists of two steps: gene filtering by Bayes factor followed by collinearity elimination via network learning. We validate our approach with two clinical data. In the study of lung cancer subtypes discrimination, we obtain a 25-gene classifier from 111 training samples, and the test on 422 independent samples achieves 95% classification accuracy. In the study of thoracic aortic aneurysm (TAA) diagnosis, 61 samples determine a 34-gene classifier, whose diagnosis accuracy on 33 independent samples achieves 82%. The performance comparisons with three other popular methods, PCA/LDA, PAM, and Weighted Voting, confirm that our approach yields superior classification accuracy and a more compact signature. Conclusions: The system biology approach presented in this paper is able to infer function-dependent transcriptional networks, which in turn can classify biological samples with high accuracy. The validation of our classifier using clinical data demonstrates the promising value of our proposed approach for disease diagnosis. © 2009 Chang and Ramoni;licensee BioMed Central Ltd.

关键词： Bayesian networks

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Negative-impedance ventilation and pressure support ventilation: A comparative study

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RESPIRATION PHYSIOLOGY 1997年第2期108卷 117-127页

作者： Poon, CS Lebowitz, HH Sidney, DA Li, SX Harvard-MIT Division of Health Sciences and Technology Rm 20A–126 Massachusetts Institute of Technology Cambridge MA 02 139 USA

Negative impedance ventilation (NIV) is a novel mode of assisted mechanical ventilation (AMV) in which the pressure support is regulated to continuously track inspiratory flow and/or volume. In this study, we have evaluated the efficacies of NIV and inspiratory pressure support (IFS) ventilation in a model of central airway obstruction in six rabbits. For both AMV modes there was an inverse relationship between the intrinsic work of breathing and alveolar pressure. Compared to IFS, NIV was found to: (1) achieve the same degree of ventilatory unloading and similar level of pulmonary ventilation with considerably lower alveolar pressure;(2) better restore the normal tidal volume and respiratory frequency;(3) yield a shorter inspiratory duty cycle, thereby helping to rest the respiratory muscles and preclude intrinsic positive end-expiratory pressure. We conclude that NIV is more efficacious than IFS in negating airway obstruction and offers a better trade-off between the risks of respiratory muscle fatigue and pressure induced complications. (C) 1997 Elsevier Science B.V.

关键词： mechanical ventilation pressure support ventilation work of breathing respiratory muscle fatigue barotrauma hemodynamic instability airway obstruction

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ADAPTIVE NEURAL-NETWORK THAT SUBSERVES OPTIMAL HOMEOSTATIC CONTROL OF BREATHING

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ANNALS OF BIOMEDICAL ENGINEERING 1993年第5期21卷 501-508页

作者： POON, CS 1. Harvard-MIT Division of Health Sciences and Technology Rm 20A-126 Massachusetts Institute of Technology 77 Massachusetts Avenue 02139 Cambridge MA

An adaptive neural network model that exhibits the optimality and homeostasis characteristics of the respiratory control system is described. Based upon the Hopfield network structure and a postulated Hebb-like respiratory synapse with correlational short-term potentiation, the model is capable of mimicking the normal ventilatory responses to exercise and CO2 inputs without the need for an explicit exercise stimulus. Results suggest the possibility of an adaptive neuronal mechanism that effects optimal homeostatic regulation of respiration in mammals.

关键词： RESPIRATION MUSCULAR EXERCISE ASSOCIATIVE LEARNING HEBBIAN SYNAPSE ADAPTATION

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Novel Genetic Risk Variants Associated with Oral Tongue Squamous Cell Carcinoma

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Head and Neck Pathology 2025年第1期19卷 45-45页

作者： Nikkilä, Rayan Mäkitie, Antti Joensuu, Heikki Markkanen, Saara Elenius, Klaus Monni, Outi Palotie, Aarno Saarentaus, Elmo Salo, Tuula Bizaki-Vallaskangas, Argyro Department of Otorhinolaryngology - Head and Neck Surgery University of Helsinki and HUS Helsinki University Hospital Helsinki Finland Finnish Cancer Registry Institute for Statistical and Epidemiological Cancer and Research Helsinki Finland Research Program in Systems Oncology Faculty of Medicine University of Helsinki Helsinki Finland Department of Oncology HUS Helsinki University Hospital and University of Helsinki Helsinki Finland Department of Otolaryngology Faculty of Medicine and Health Technology Tampere University Tampere Finland The Wellbeing Services County of Pirkanmaa Tampere Finland Institute of Biomedicine and MediCity Research Laboratory University of Turku Turku Finland Turku Bioscience Centre University of Turku and Åbo Akademi University Turku Finland Department of Oncology Turku University Hospital Turku Finland iCAN Digital Precision Cancer Medicine Flagship University of Helsinki Helsinki Finland Applied Tumor Genomics Research Program Faculty of Medicine University of Helsinki Helsinki Finland Institute for Molecular Medicine Finland and the Helsinki Institute of Life Science University of Helsinki Helsinki Finland The Stanley Center for Psychiatric Research and Program in Medical and Population Genetics The Broad Institute of MIT and Harvard Cambridge MA United States Analytic and Translational Genetics Unit Department of Medicine Department of Neurology and Department of Psychiatry Massachusetts General Hospital Boston MA United States Department of Oral and Maxillofacial Diseases University of Helsinki Helsinki Finland Translational Immunology Research Program Faculty of Medicine University of Helsinki Helsinki Finland Department of Pathology HUS Helsinki University Hospital Helsinki Finland Research Unit of Population Health Faculty of Medicine University of Oulu Oulu Finland Medical Research Center Oulu University Hospital Oulu Finland

Purpose: Limited data from genome-wide association studies (GWAS) focusing on oral tongue squamous cell carcinoma (OTSCC) are available. The present study was conducted to explore genetic associations for OTSCC. Methods: A GWAS on 376 cases of OTSCC was conducted using the FinnGen Data Freeze-12 dataset. The case-cohort included 205 males and 171 females. Cases with malignancies involving the base of the tongue or lingual tonsil were excluded from the case-cohort. Individuals with no recorded history of malignancy were used as controls (n = 407,067). A Phenome-wide association study (PheWAS) was performed for the lead variants to assess their co-associations with other cancers. Results: GWAS analysis identified three genome-wide significant loci associated with OTSCC (p < 5 × 10–8), located at 5p15.33 (rs27067 near gene LINC01511), 10q24 (rs1007771191 near RPS3AP36), and 20p12.3 (rs1438070080 near PLCB1), respectively. PheWAS showed associations of rs27067 mainly with prostate cancer (OR = 1.06, p = 5.41 × 10^–7), and seborrheic keratosis (OR = 1.11, p = 1.51 × 10^–11). A co-directional effect with melanoma was also observed (OR = 0.93, p = 6.24 × 10^–5). Conclusion: The GWAS detected two novel genetic associations with OTSCC. Further research is needed to identify the genes at these loci that contribute to the molecular pathogenesis of OTSCC. © The Author(s) 2025.

关键词： FinnGen Genetic variant Genome-wide association Single nucleotide polymorphism Tongue cancer

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Electroporation: a unified, quantitative theory of reversible electrical breakdown and mechanical rupture in artificial planar bilayer membranes

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Journal of Electroanalytical Chemistry 1991年第2期320卷 163-182页

作者： Barnett, Alan Weaver, James C. Harvard - MIT Division of Health Sciences and Technology Cambridge MA 02139 United States

We present a quantitative theory of electroporation of artificial planar lipid bilayer membranes. Assuming that aqueous pores are involved in electroporation, we describe the pore population of the membrane by the density function n (r, t), where n (r, t) dr is the number of pores with radius between r and r + dr at time t. We further assume that there is a minimum pore size r_min, that pores of radius r_min are created and destroyed by thermal fluctuations, and that the pore creation rate is proportional to exp(aΔφ²_m/kT), where a is a constant, Δφ_m is the membrane voltage, k is Boltzmann's constant, and T is the absolute temperature. We use a simple formula for the conductance of a pore as a function of radius, the expression for the pore energy previously derived by Pastushenko and Chizmadzhev, and a simple model of the external circuit. We solve the equations numerically and compare the solutions to the results of charge pulse experiments. In a charge-pulse experiment a membrane suffers one of four possible fates: (1) a slight increase in electrical conductance, (2) mechanical rupture, (3) incomplete reversible electrical breakdown, resulting in incomplete discharge of the membrane, or (4) reversible electrical breakdown (REB), resulting in complete discharge of the membrane. In agreement with experiment, this theory describes these four fates and predicts that the fate in any particular experiment is determined by the properties of the membrane and the duration and amplitude of the charging pulse. © 1991.

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Demographic variation in charitable giving and helping across 22 countries in the Global Flourishing Study

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Scientific Reports 2025年第1期15卷 1-16页

作者： Nakamura, Julia S. Węziak-Białowolska, Dorota Woodberry, Robert D. Kubzansky, Laura D. Shiba, Koichiro Padgett, R. Noah Johnson, Byron R. VanderWeele, Tyler J. Department of Psychology University of British Columbia 2136 West Mall Vancouver V6T 1Z4 BC Canada Department of Quantitative Methods and Information Technology Kozminski University Warsaw Poland Human Flourishing Program Institute for Quantitative Social Science Harvard University Cambridge United States Institute for Studies of Religion Baylor University Waco United States Department of Social and Behavioral Sciences Harvard T.H. Chan School of Public Health Boston United States School of Public Health Boston University Boston United States Department of Biostatistics Harvard T.H. Chan School of Public Health Boston United States Department of Epidemiology Harvard T.H. Chan School of Public Health Boston United States

Prosocial behaviors play a vital role in promoting individual and societal well-being. Charitable giving and helping strangers are two important expressions of prosociality;yet we know little about how these behaviors differ across sociodemographic indicators cross-nationally. Using data from the Global Flourishing Study, a diverse and international sample of 202,898 individuals across 22 countries, we examined distributions of charitable giving and helping (binary variables, yes/no) across nine demographic factors (age, gender, marital status, employment status, religious service attendance, education, immigration status, race and ethnicity, and religious affiliation) and culturally diverse countries. Unadjusted proportions of charitable giving and helping in the past month varied substantially between countries for charitable giving (from 0.10 [Japan] to 0.79 [Indonesia]) and helping (from 0.11 [Japan] to 0.83 [Nigeria]). Random effects meta-analyses confirmed that rates of charitable giving and helping differed among some demographic groups (e.g., more charitable giving with older age, less helping with older age, increased charitable giving and helping with more education) and that rates of charitable giving and helping across all demographic factors differed between countries. Better understanding how various sociodemographic factors may be associated with prosocial behaviors, and how these associations differ internationally, may help to inform interventions designed to enhance prosociality around the world. © The Author(s) 2025.

关键词： Charitable giving Cross-national Demographics Global Flourishing Study Helping strangers Prosocial behavior

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Reptation of microtubules in F-actin networks: Effects of filament stiffness and network topology on reptation dynamics

Reptation of microtubules in F-actin networks: Effects of fi...

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Proceedings of the 1997 MRS Fall Meeting

作者： Shah, Jagesh V. Flanagan, Lisa A. Bahk, David Janmey, Paul A. Harvard-MIT Div of Health Sciences and Technology Cambridge United States

The thermally driven motions of fluorescently labeled microtubules embedded in a network of filamentous actin polymers are analyzed as the diffusion of a rod-like polymer within a virtual tube formed by the surrounding semiflexible actin filaments. The apparent diffusion constant parallel to the tube scales with the inverse of the microtubule length and the magnitude is consistent with diffusion through a medium with a viscosity of approximately 10 centipoise. Introduction of crosslinks between the actin filaments does not alter the diffusion of the microtubules in the actin network.

关键词： Proteins

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Mutual information analysis of temporal patterns of occurrence of ventricular premature beats

Mutual information analysis of temporal patterns of occurren...

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Proceedings of the 1995 IEEE Engineering in Medicine and Biology 17th Annual Conference and 21st Canadian Medical and Biological Engineering Conference. Part 2 (of 2)

作者： Osaka, Motohisa Saitoh, Hirokazu Someya, Tomoko Hayakawa, Hirokazu Cohen, Richard J. Harvard-MIT Div of Health Sciences and Technology Cambridge United States

The importance of ventricular premature beats (VPB's) results from their possible association with an increased risk for cardiac sudden death. However, little is known about patterns of VPB generation. We applied mutual information (MI) to quantify how VPB's are generated with mutual dependence over time, with larger numbers indicating more mutual relation, and examined its relationship with VPB's/day and Lown grading system. Twenty subjects (Lown grade3, n=1;4A, n=9;4B, n=10) were identified retrospectively as having more than 3000 of VPB's during 24-hour Holter monitoring. Ten of these patients had no apparent heart disease (N-group). The other ten had coronary heart disease (C-group). MI had no significant correlation with VPB's/day and showed no significant difference between Lown grades (4A, 2.1±1.4bits vs 4B, 2.3±1.4bits). We found that values of MI were variable among N-group (2.2±1.3bits) and C-group (2.4±1.5bits). The values of MI of time series of random numbers were all zeros. We thought that the mechanism of VPB's in patients with strong generalized dependence of VPB's might be different from that in patients with weak generalized dependence, particularly with random generation of VPB's. The absent relations with VPB's/day and Lown grades suggested that MI of VPB's could be an independent marker.

关键词： Electrocardiography

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Variable block-sized vector quantization of grayscale images with unconstrained tiling

Variable block-sized vector quantization of grayscale images...

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Visual Communications and Image Processing '90

作者： Boxerman, Jerrold L. Lee, Ho John Harvard MIT Div of Health Sciences and Technology Cambridge United States

ISBN: (纸本)0819404217

This paper discusses the design and performance of a variable block-sized vector qunatizer with unconstrained tiling (UTVQ), a novel block coder that segments the input image into an unconstrained tiling of various-sized, non-overlapping rectangular regions, each of which is then coded with a vector quantizer. UTVQ is compared with the more constrained quadtree vector quantizer (QTVQ) approach. A transmission scheme is described which reduces the overhead required to convey UTVQ segmentation geometry. Several UTVQ segmentation strategies are presented, and mean-residual codebook generation methods with appropriate side stream compression techniques are discussed. UTVQ outperforms QTVQ in a projected rate sense, since it can segment an image into fewer blocks, each of which satisfies a specified homogeneity constraint. Furthermore, UTVQ outperforms QTVQ in a rate-distortion sense for certain applications. The maximum separation which we have observed between our experimental UTVW rate-distortion curves and those for the QTVQ system is 0.4 dB.

关键词： Image Processing

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