The Cambridge encyclopedia of human growth and development

The Cambridge Encyclopedia of Human Growth and Development. Edited by Stanley J. Ulijaszek, Francis E. Johnson, and Michael A. Preece. Cambridge, UK: Cambridge University Press. 1998. 497 pp. ISBN 0-521-56046-2. $95.00 (cloth).     

Damaged-bone adaptation under steady homogeneous stress

In this work an extension of the adaptive-elasticity theory is proposed in order to include the contribution of bone microdamage as a stimulus. Some aspects of damaged-bone tissue adaptation, brought about by a change of the daily loading history, are investigated. In particular, under the assumption of a small strain approximation and isothermal conditions, the solution of the remodeling rate equation for steady homogeneous stress is discussed and the damage effect upon the remodeling time constant is shown. The result is both theoretical and numerical, based on a recent theory of internal damaged-bone remodeling (Ramtani, S., and Zidi, M., 1999, "Damaged-Bone Remodeling Theory: Thermodynamical Approach, " Mechanics Research Communications, Vol. 26, pp. 701-708. Ramtani, S., and Zidi, M., 2001, "A Theoretical Model of the Effect of Continum Damage on a Bone Adaption Model," Journal of Biomechanics, Vol. 34, pp. 471-479) and motivated by the works of Cowin, S. C., and Hegedus, D. M., 1976, "Bone Remodeling I: Theory and Adaptive Elasticity," Journal of Elasticity, Vol. 6, pp. 471-479 and Hegedus, D. H., and Cowin, S. C., 1976, "Bone Remodeling II: Small Strain Adaptive Elasticity," Journal of Elasticity, Vol. 6, pp. 337-352.     

Hyperelastic anisotropic microplane constitutive model for annulus fibrosus

In a recent paper, Peng et al. (2006, "An Anisotropic Hyperelastic Constitutive Model With Fiber-Matrix Interaction for the Human Annulus Fibrosis," ASME J. Appl. Mech., 73(5), pp. 815-824) developed an anisotropic hyperelastic constitutive model for the human annulus fibrosus in which fiber-matrix interaction plays a crucial role in simulating experimental observations reported in the literature. Later, Guo et al. (2006, "A Composites-Based Hyperelastic Constitutive Model for Soft Tissue With Application to the Human Fibrosis," J. Mech. Phys. Solids, 54(9), pp. 1952-1971) used fiber reinforced continuum mechanics theory to formulate a model in which the fiber-matrix interaction was simulated using only composite effect. It was shown in these studies that the classical anisotropic hyperelastic constitutive models for soft tissue, which do not account for this shear interaction, cannot accurately simulate the test data on human annulus fibrosus. In this study, we show that the microplane model for soft tissue developed by Caner and Carol (2006, "Microplane Constitutive Model and Computational Framework for Blood Vessel Tissue," ASME J. Biomech. Eng., 128(3), pp. 419-427) can be adjusted for human annulus fibrosus and the resulting model can accurately simulate the experimental observations without explicit fiber-matrix interaction because, in microplane model, the shear interaction between the individual fibers distributed in the tissue provides the required additional rigidity to explain these experimental facts. The intensity of the shear interaction between the fibers can be adjusted by adjusting the spread in the distribution while keeping the total amount of the fiber constant. A comparison of results obtained from (i) a fiber-matrix parallel coupling model, which does not account for the fiber-matrix interaction, (ii) the same model but enriched with fiber-matrix interaction, and (iii) microplane model for soft tissue adapted to annulus fibrosus with two families of fiber distributions is presented. The conclusions are (i) that varying degrees of fiber-fiber and fiber-matrix shear interaction must be taking place in the human annulus fibrosus, (ii) that this shear interaction is essential to be able to explain the mechanical behavior of human annulus fibrosus, and (iii) that microplane model can be fortified with fiber-matrix interaction in a straightforward manner provided that there are new experimental data on distribution of fibers, which indicate a spread so small that it requires an explicit fiber-matrix interaction to be able to simulate the experimental data.     

Validation of a pressure diameter method for determining modulus and strain of collagen engagement for long branches of bovine pulmonary arteries

Recent studies have shown that capacitance measurements of large arteries provide better prognosis and diagnosis than tests of resistance alone in pulmonary hypertension (Mahapatra et al., 2006, "Relationship of Pulmonary Arterial Capacitance and Mortality in Idiopathic Pulmonary Arterial Hypertension," J. Am. Coll. Cardiol., 47(4), pp. 799-803; Reuben, 1971, "Compliance of the Human Pulmonary Arterial System in Disease," Circ. Res., 29, pp. 40-50]. Decreased arterial capacitance causes increased load to the heart and is the direct result of increased stiffness and elastic modulus of the arterial wall. Here, we validate a pressure-diameter (PD) method for comparing the elastic modulus and collagen engagement for post-hilar pulmonary arteries with a large range of arterial diameter. The tissue mechanics of the post-hilar arteries are not well-characterized in pulmonary hypertension. It is believed that future studies with this method will provide useful insight into the role of passive tissue mechanics of these arteries in the pathophysiology of pulmonary hypertension, eventually improving clinical diagnosis, prognosis, and treatment. Post-hilar pulmonary arteries, excised from healthy and hypertensive calves and healthy cows, were inflated over a range of 0 [mm Hg] to 110 [mm Hg] in an isolated tissue bath. Internal pressure was recorded with an electric pressure catheter. Artery diameter and longitudinal stretch were recorded photographically. Stress-strain data curves were extracted using Lame's law of thick-walled tubes. Radial strips were removed from each section and tested in a uniaxial (MTS) tester for validation. Both the elastic modulus and collagen engagement strain were similar to results obtained by more traditional means. The average difference between measured values of the two methods for collagen engagement strain was 3.3% of the average value of the engagement strain. The average difference between the measured values of the two methods for modulus of elasticity was 7.4% of the average value of the modulus. The maximum, theoretical, relative error for the stress determined with the PD method was calculated at 20.3%. The PD method proved to be a suitable replacement for uniaxial strain tests in comparing collagen engagement strains. The method allowed faster testing of tissues of multiple diameters, while removing the effect of end conditions. The PD method will be of further utility in continued study of tissue mechanics in pulmonary hypertension studies.     

BOOK REVIEWS

Book reviewed in this issue. Lambers, H., Cambridge, M. L., Konigs, H. & Pons, T. L. (eds.) 1989. Causes and Consequences of Variation in Growth Rate and Productivity of Higher Plants , x + 354 pp. SPB Academic Publishing, The Hague. ISBN 90–5103–033–9. Price: USD 90.00.     

Membrane stress and internal pressure in a red blood cell freely suspended in a shear flow.

Presented is an algorithm for the approximate calculation of the membrane stress distribution and the internal pressure of a steadily tank-treading red cell. The algorithm is based on an idealized ellipsoidal model of the tank-treading cell (Keller, S.R., and R. Skalak, 1982, J. Fluid Mech., 120:27-47) joined with experimental observations of projected length, width, and tank-treading frequency. The results are inexact because the membrane shape and velocity are assumed a priori, rather than being determined via appropriate material constitutive relations for the membrane; these results are, nevertheless, believed to be approximately correct, and show that internal pressure builds up slowly as cell elongation increases, rising more rapidly as the deformed cell approaches the limiting geometry of a prolate ellipsoid. The maximum shear stress resultant in the membrane was found to be below but approaching the yield point range at the highest shear rate applied.     

Numerical simulation of mass transport in a microchannel bioreactor with cell micropatterning

Micropatterning of two different cell types based on surface modification allows spatial control over two distinct cell subpopulations. This study considers a micropatterned coculture system, which has release and absorption parts alternately arranged at the base, and each part has a single cell type. A micropattern unit was defined and within each unit, there are one release part and one absorption part. The cells in the absorption parts consume species, which are secreted by the cells in the release parts. The species concentrations at the micropatterned cell base were computed from a three-dimensional numerical flow model incorporating mass transport. Different combined parameters were developed for the release and absorption parts to make the data collapse in each part. Combination of the collapse data in the release and absorption parts can be used to predict the concentration distribution through the whole channel. The correlated results were applied to predict the critical length ratio of the release and absorption parts for an actual micropatterned system (Bhatia et al., 1999, "Effect of Cell-Cell Interactions in Preservation of Cellular Phenotype: Co-Cultivation of Hepatocytes and Nonparenchymal Cell," FASEB J. 13, pp. 1883-1900) to avoid species insufficiency based on basic fibroblast growth factor (bFGF). The mass transfer effectiveness was found to be higher with more numbers of micropattern units. The optimal condition for micropatterned coculture bioreactors is achieved by having the product of the length ratio and the reaction ratio equal to 1. This condition was used to optimize the mass transfer in the micropatterned system (Bhatia et al., 1999, "Effect of Cell-Cell Interactions in Preservation of Cellular henotype: Co-Cultivation of Hepatocytes and Nonparenchymal Cell," FASEB J. 13, pp. 1883-1900) based on bFGF.     

Determination of red blood cell membrane viscosity from rheoscopic observations of tank-treading motion.

Measurements of the dimensions and membrane rotational frequency of individual erythrocytes steadily tank-treading in a rheoscope are used to deduce the surface shear viscosity of the membrane. The method is based on an integral energy principle which says that the power supplied to the tank-treading cell by the suspending fluid is equal to the rate at which energy is dissipated by viscous action in the membrane and cytoplasm. The integrals involved are formulated with the aid of an idealized mathematical model of the tank-treading red blood cell (RBC) (Keller and Skalak, 1982, J. Fluid Mech., 120:24-27) and evaluated numerically. The outcome is a surface-averaged value of membrane viscosity which is representative of a finite interval of membrane shear rate. The numerical values computed show a clear shear-thinning characteristic as well as a significant augmentation of viscosity with cell age and tend toward agreement with those determined for the rapid phase of shape recovery in micropipettes (Chien, S., K.-L. P. Sung, R. Skalak, S. Usami, and A. Tozeren, 1978, Biophys. J., 24:463-487). The computations also indicate that the rate of energy dissipation in the membrane is always substantially greater than that in the cytoplasm.     

Modelling cartilage mechanobiology

The growth, maintenance and ossification of cartilage are fundamental to skeletal development and are regulated throughout life by the mechanical cues that are imposed by physical activities. Finite element computer analyses have been used to study the role of local tissue mechanics on endochondral ossification patterns, skeletal morphology and articular cartilage thickness distributions. Using single-phase continuum material representations of cartilage, the results have indicated that local intermittent hydrostatic pressure promotes cartilage maintenance. Cyclic tensile strains (or shear), however, promote cartilage growth and ossification. Because single-phase material models cannot capture fluid exudation in articular cartilage, poroelastic (or biphasic) solid/fluid models are often implemented to study joint mechanics. In the middle and deep layers of articular cartilage where poroelastic analyses predict little fluid exudation, the cartilage phenotype is maintained by cyclic fluid pressure (consistent with the single-phase theory). In superficial articular layers the chondrocytes are exposed to tangential tensile strain in addition to the high fluid pressure. Furthermore, there is fluid exudation and matrix consolidation, leading to cell 'flattening'. As a result, the superficial layer assumes an altered, more fibrous phenotype. These computer model predictions of cartilage mechanobiology are consistent with results of in vitro cell and tissue and molecular biology experiments.     

Identification of para-Cresol as a Growth Factor for Methanoplanus endosymbiosus

Growth of the methanogenic bacterium Methanoplanus endosymbiosus is dependent on the presence of ruminal fluid. Ruminal fluid could be replaced by the eluate of a rumen-derived anaerobic digester. From the eluate of the digester, a growth-stimulatory component was purified and identified as p-cresol. Authentic p-cresol supported a half-maximal growth rate of the organism at 50 nM concentration.     

Book reviews

Walter A. Jackson, GUNNAR MYRDAL AND AMERICA'S CONSCIENCE: SOCIAL ENGINEERING AND RACIAL LIBERALISM, 1938–1987, Chapel Hill, NC: University of North Carolina Press, 1990, xxi + 447pp., $38.45.

Sissela Bok, ALVA MYRDAL: A DAUGHTER'S MEMOIR, Reading, MA: Addison‐Wesley Publishing Co., 1991, xvi + 375pp., $22.00 and $12.95 (paper).

David W. Southern, GUNNAR MYRDAL AND BLACK WHITE RELATIONS: THE USE AND ABUSE OF AN AMERICAN DILEMMA 1944–1969, Baton Rouge, LA: Louisiana State University Press, 1987, xviii + 338pp., $37.50.

Elazar Barkan, THE RETREAT FROM SCIENTIFIC RACISM: CHANGING CONCEPTS OF RACE IN BRITAIN AND THE UNITED STATES BETWEEN THE WORLD WARS, Cambridge: Cambridge University Press, 1991, xxii + 508pp., £37.50.

Dorothy Ross, THE ORIGINS OF AMERICAN SOCIAL SCIENCE, Cambridge: Cambridge University Press, 1991, xxii + 508pp., £35.00 and £16.95 (paper).     

Haloarcula marismortui (Volcani) sp. nov., nom. rev., an extremely halophilic bacterium from the Dead Sea

An extremely halophilic red archaebacterium isolated from the Dead Sea (Ginzburg et al., J. Gen. Physiol. 55: 187-207, 1970) belongs to the genus Haloarcula and differs sufficiently from the previously described species of the genus to be designated a new species; we propose the name Haloarcula marismortui (Volcani) sp. nov., nom. rev. because of the close resemblance of this organism to "Halobacterium marismortui," which was first described by Volcani in 1940. The type strain is strain ATCC 43049.     

Cultural diversity and schooling

Ashley H. Robins, BIOLOGICAL PERSPECTIVES ON HUMAN PIGMENTATION, (Cambridge Studies in Biological Anthropology, 7), Cambridge: Cambridge University Press, 1991, xiii + 253 pp., £37.50.

Ulfried Geuter, THE PROFESSIONALIZATION OF PSYCHOLOGY IN NAZI GERMANY. Cambridge Studies in the History of Psychology, Cambridge: Cambridge University Press, 1992, v‐xxi + 335 pp., npl.

Clare Midgley, WOMEN AGAINST SLAVERY. THE BRITISH CAMPAIGNS, 1780–1870, London: Routledge, 1992, xii + 281 pp., £37.50.

Maryinez Lyons, THE COLONIAL DISEASE: A SOCIAL HISTORY OF SLEEPING SICKNESS IN NORTHERN ZAIRE, 1900–1940, Cambridge: Cambridge University Press, 1992, xvi + 335 pp., £50.00.

Wim van Binsbergen, TEARS OF RAIN: ETHNICITY AND HISTORY IN CENTRAL WESTERN ZAMBIA, London and New York: Kegan Paul International, 1992, 495 pp., £45.00.

Albert B. Robillard (ed.) SOCIAL CHANGE IN THE PACIFIC ISLANDS, London: Kegan Paul International, 1992, xvi + 507 pp., £45.

Sarah Radcliffe and Sallie Westwood (eds) ‘VIVA’: WOMEN AND POPULAR PROTEST IN LATIN AMERICA, London: Routledge, 1993, 270 pp., £12.99 pb; £40.00 hb.

Cindi Katz and Janice Monk (eds) FULL CIRCLES: GEOGRAPHIES OF WOMEN OVER THE LIFECOURSE, London: Routledge, 1993, 317 pp., £12.99 pb; £40 hb.

Hans van Amersfoort and Hans Knippenberg (eds), STATES AND NATIONS. THE REBIRTH OF THE ‘NATIONALITIES QUESTION’ IN EUROPE, Netherlands Geographical Studies 137, Amsterdam: Koninklijk Nederlands Aardrijkskundig Genootschap, 1991, 189 pp., Dfl. 29.50.

Elizabeth D. Huttman, Wim Blauw and Juliet Saltman (eds), URBAN HOUSING SEGREGATION OF MINORITIES IN WESTERN EUROPE AND THE UNITED STATES, Durham, NC: Duke University Press, 1991, xiii + 431 pp., npl.

Roger Daniels, Sandra C. Taylor, and Harry H. L. Kitano (eds) JAPANESE AMERICANS: FROM RELOCATION TO REDRESS, Seattle, WA: University of Washington Press, 1992, 264 pp., $17.95 US (paper only).

David J. O'Brien and Stephen S. Fugita, THE JAPANESE AMERICAN EXPERIENCE, Bloomington and Indianapolis: Indiana University Press, 1991, 178 pp., £8.99 (paper).

Paul James Rutledge, THE VIETNAMESE EXPERIENCE IN AMERICA, Bloomington and Indianapolis: Indiana University Press, 1992, 173 pp., npl.     

Book Review

GuidetoStandardFlorasoftheWorld,2 nd Ed.,byDavidG .Frodin,CambridgeUniversityPress,NewYork.April2 0 0 1 .xxiv,1 1 0 0pp .ISBN 0 - 52 1 - 790 77- 8.Price:US＄2 4 0 0 0 (hardcover) .1 stEd .xx,61 9pp.CUP 1 984.ISBN 0 - 52 1 - 2 3688- 6 .Finallyaftermorethansixteenyears,thesecondeditionoftheGuidetoStandardFloraoftheWorldwaspublishedwithtwiceasmanypagesasfirsteditionin1 984.ThisrevisedGuidecertainlywillbeavaluablereferenceforbothama teursandprofessionalworldwide.Topresent,therehavebe…     

A mathematical framework for modelling cambial surface evolution using a level set method

Background and Aims

During their lifetime, tree stems take a series of successive nested shapes. Individual tree growth models traditionally focus on apical growth and architecture. However, cambial growth, which is distributed over a surface layer wrapping the whole organism, equally contributes to plant form and function. This study aims at providing a framework to simulate how organism shape evolves as a result of a secondary growth process that occurs at the cellular scale.

Methods

The development of the vascular cambium is modelled as an expanding surface using the level set method. The surface consists of multiple compartments following distinct expansion rules. Growth behaviour can be formulated as a mathematical function of surface state variables and independent variables to describe biological processes.

Key Results

The model was coupled to an architectural model and to a forest stand model to simulate cambium dynamics and wood formation at the scale of the organism. The model is able to simulate competition between cambia, surface irregularities and local features. Predicting the shapes associated with arbitrarily complex growth functions does not add complexity to the numerical method itself.

Conclusions

Despite their slenderness, it is sometimes useful to conceive of trees as expanding surfaces. The proposed mathematical framework provides a way to integrate through time and space the biological and physical mechanisms underlying cambium activity. It can be used either to test growth hypotheses or to generate detailed maps of wood internal structure.     

Managing postoperative pain in adult outpatients: a systematic review and meta-analysis comparing codeine with NSAIDs

BACKGROUND:Analgesics that contain codeine are commonly prescribed for postoperative pain, but it is unclear how they compare with nonopioid alternatives. We sought to compare the effectiveness of codeine and nonsteroidal anti-inflammatory drugs (NSAIDs) for adults who underwent outpatient surgery.METHODS:We conducted a systematic review and meta-analysis of randomized controlled trials comparing codeine and NSAIDs for postoperative pain in outpatient surgery. We searched MEDLINE and Embase from inception to October 2019 for eligible studies. Our primary outcome was the patient pain score, converted to a standard 10-point intensity scale. Our secondary outcomes were patient-reported global assessments and adverse effects. We used random-effects models and grading of recommendations assessment, development and evaluation (GRADE) to assess the quality of evidence.RESULTS:Forty studies, including 102 trial arms and 5116 patients, met inclusion criteria. The studies had low risk of bias and low-to-moderate heterogeneity. Compared with codeine, NSAIDs were associated with better pain scores at 6 hours (weighted mean difference [WMD] 0.93 points, 95% confidence interval [CI] 0.71 to 1.15) and at 12 hours (WMD 0.79, 95% CI 0.38 to 1.19). Stronger NSAID superiority at 6 hours was observed among trials where acetaminophen was coadministered at equivalent doses between groups (WMD 1.18, 95% CI 0.87 to 1.48). NSAIDs were associated with better global assessments at 6 hours (WMD −0.88, 95% CI −1.04 to −0.72) and at 24 hours (WMD −0.67, 95% CI −0.95 to −0.40), and were associated with fewer adverse effects, including bleeding events.INTERPRETATION:We found that adult outpatients report better pain scores, better global assessments and fewer adverse effects when their postoperative pain is treated with NSAIDs than with codeine. Clinicians across all specialties can use this information to improve both pain management and opioid stewardship.

Outpatient surgical procedures are now more common than inpatient procedures, given the development of less invasive techniques, the drive for health care efficiency, and improvements in anesthesia and pain management. ^1–4 Postoperative pain management after outpatient procedures often includes low-potency or low-dose opioids.⁵ Codeine use is widespread in this setting and codeine remains the most commonly prescribed opioid in many countries, including Canada.^6–9 However, its efficacy is variable, its potency is low and its use is associated with risks of severe adverse effects and misuse.¹⁰ Amid the ongoing opioid crisis, management of pain and potential opioid misuse is important across all medical and dental specialties.¹¹Nonsteroidal anti-inflammatory drugs (NSAIDs) are an alternative to low-potency opioids. The potency, effects and toxicity of NSAIDs depend on the degree to which they inhibit cyclooxygenase 1 and 2 activity. Their main adverse effects are gastrointestinal bleeding, renal impairment and myocardial infarction with long-term use.^12–15 Postoperative pain can be effectively managed with NSAIDs, and NSAIDs have been shown to reduce opioid consumption in postoperative patients.¹⁶Given how commonly these medications are used, and the uncertainty in their comparative efficacy and safety, we sought to compare pain and safety outcomes for codeine-based medications and NSAIDs among adults who underwent outpatient surgery through a systematic review and meta-analysis of randomized controlled trials (RCTs).     

BOOK REVIEWS

Book reviewed in this article: Rundel, P.W., Smith, A.P. & Meinzer, F.C. (eds.) 1994. Tropical Alpine Environments. Plant form and function. xi + 376 pp. Cambridge University Press, Cambridge. ISBN 0–521–42089-X. Price: GBP 65.-.     

Rhodospirillum sodomense,sp. nov., a Dead Sea rhodospirillum species

A new species of halophilic anoxygenic purple bacteria of the genus Rhodospirillum is described. The new organism, isolated from water/sediment of the Dead Sea, was vibrio-shaped and an obligate halophile. Growth was best at 12% NaCl, with only weak growth occurring at 6% or 21% NaCl. Growth occurred at Mg²⁺ concentrations up to 1 M but optimal growth was obtained at 0.05–0.1 M Mg²⁺. Bromide was well tolerated as an alternative anion to chloride. The new organism is an obligate phototroph, growing photoheterotrophically in media containing yeast extract and acetate or a few other organic compounds. Growth of the Dead Sea Rhodospirillum species under optimal culture conditions was slow (minimum t_d 20 h). Cells contained bacteriochlorophyll a and carotenoids of the spirilloxanthin series and mass cultures were pink in color. Absorption spectra revealed the presence of a B875 (light-harvesting I) but no B800/B850 (light-harvesting II) photopigment complex. The new organism shares a number of properties with the previously described halophilic phototrophic bacterium Rhodospirillum salinarum and was shown to be related to this phototroph by 16S rRNA sequencing. However, because of its salinity requirements, photosynthetic properties, and isolation from the Dead Sea, the new phototroph is proposed as a new species of the genus Rhodospirillum, R. sodomense.     

A physical model of ATP-induced actin-myosin movement in vitro.

The nature of the mechanism limiting the velocity of ATP-induced unidirectional movements of actin-myosin filaments in vitro is considered. In the sliding process two types of "cyclic" interactions between myosin heads and actin are involved, i.e., productive and nonproductive. In the productive interaction, myosin heads split ATP and generate a force which produces sliding between actin and myosin. In the nonproductive interaction "cycle," on the other hand, myosin heads rapidly attach to and detach from actin "reversibly," i.e., without splitting ATP or generating an active force. Such a nonproductive interaction "cycle" causes irreversible dissipation of sliding energy into heat, because the myosin cross-bridges during this interaction are passive elastic structures. This consideration has led us to postulate that such cross-bridges, in effect, exert viscous-like frictional drag on moving elements. Energetic considerations suggest that this frictional drag is much greater than the hydrodynamic viscous drag. We present a model in which the sliding velocity is limited by the balance between the force generated by myosin cross-bridges in the productive interaction and the frictional drag exerted by other myosin cross-bridges in the nonproductive interaction. The model is consistent with experimental findings of in vitro sliding, including the dependence of velocity on ATP concentration, as well as the sliding velocity of co-polymers of skeletal muscle myosin and phosphorylated and unphosphorylated smooth muscle myosins.