bluuebunny/crossref_metadata_2025 huggingface dataset:
Field-monitored variations of soil moisture and matric suction in a saprolite slope
Authors: Li A G , Yue Z Q , Tham L G , Lee C F , Law K T
Published: March 2005

A full-scale field experiment has been conducted in an instrumented saprolite slope in Hong Kong. Soil moisture probes, tensiometers, piezometers, inclinometers, earth pressure cells, and a rain gauge were installed in the slope before and during excavation of a cut. This paper presents the results from soil moisture probes, tensiometers, and piezometers to reveal the surface infiltration process. The soil moisture and matric suction results show that the maximum "wetting front" during the wet season was limited to the top 3 m of soil, and a transient perched water table could develop in the soil during a very heavy rainstorm. A new method based on the variation of volumetric water content in the soil is proposed to analyze rainfall infiltration. The results indicate the following phenomena: (i) rainfall infiltration was around 70% of the total rainfall, (ii) the infiltrated water mainly increased the soil moisture content of the soil at shallow depths, and (iii) the surface vertical infiltration had a very limited effect on the permanent groundwater table at depth. The wetting-front analysis shows that the unsaturated wetting band theory can be used to assess the movement of the wetting front in the unsaturated saprolite soil.Key words: rainfall infiltration, moisture content, matric suction, wetting front, field instrumentation.
An analysis of stressstrain behaviour and wetting effects on quarried rock shells
Authors: Escuder Ignacio , Andreu Joaquin , Rechea Manuel
Published: March 2005

The analysis of stressstrain behaviour and the effects of submergence on quarried rock shells, used mainly in dams but also in road construction, is of major importance from both economic and safety points of view. The research work presented here starts with an in-depth review of the nonlinear elastic procedure widely used in rockfill analyses since 1970, its later application to simulate wetting effects, and the latest published modifications to the so-called hyperbolic stressstrain model. An update of the existing wetting simulation procedure has been formulated, calculation routines to analyze constructional behaviour and wetting effects on rockfills have been implemented, and the methodology developed has been applied to a structure 100 m high. Calculation routines have been written to run in FLAC, a finite difference based code that incorporates a programming language. The analyzed structure is part of a road rockfill located at the Contreras Reservoir in Spain and consists specifically of two shell-shaped cross sections subjected to the influence of submergence. The results are expected to be useful in estimating collapse settlements in the upstream shells of earth-core dams.Key words: elasticity, stressstrain, rockfills, behaviour, numerical, dams.
A concise algorithm for computing the factor of safety using the MorgensternPrice method
Authors: Zhu D Y , Lee C F , Qian Q H , Chen G R
Published: March 2005

A concise algorithm is proposed in this paper for the calculation of the factor of safety of a slope using the MorgensternPrice method. Based on force and moment equilibrium considerations, two expressions are derived for the factor of safety Fs and the scaling factor λ, respectively, both in relatively simple forms. With this algorithm and assumed initial values of Fs and λ, the solutions for Fs and λ are found to converge within a few iterations. Compared to other procedures, the present algorithm possesses the advantages of simplicity and high efficiency in application. It is rather straightforward to implement this algorithm into a computer program.Key words: slope, stability, factor of safety, limit equilibrium method.
A new mathematical model for resonant-column measurements including eddy-current effects
Authors: Cascante Giovanni , Vanderkooy John , Chung Wilson
Published: March 2005

Wave velocity and attenuation are commonly studied in the laboratory with the resonant-column device (American Society for Testing and Materials standard), which is driven by a set of coils and magnets. This paper presents a new and robust mathematical model of the electromechanical resonant-column system. The model is used to compute various transfer functions. Eddy currents, a new source of damping identified in the resonant-column device, introduce damping proportional to the velocity of the magnets. Eddy-current damping is considered in the mathematical model. A testing program is devised to calibrate the resonant column with three aluminum probes. Experimental and theoretical results show an excellent agreement (4% maximum error). Exploratory results are presented for a dry-sand specimen. A resonant-column device is modified to demonstrate the significant effect of the induced voltage (electromotive force (EMF)) on damping ratio if tests are not based on current measurements. Free-vibration tests on aluminum specimens and a dry-sand specimen show a significant effect of the induced EMF (up to 400% increase in damping for the sand specimen). The induced voltage depends on the resonant frequency and damping of the specimen. In the case of aluminum probes, eddy-current damping represents 20150 times the material damping of the specimen. Preliminary results on dry sand show that eddy-current damping represents up to a 15% increase in damping ratio. However, the magnitude of eddy-current damping depends on the configuration and materials used in the resonant-column device. The smaller the damping ratio of the specimen is, the more important the eddy-current damping becomes.Key words: damping, eddy currents, mechanical waves, resonant-column device, shear modulus, wave velocity.
Impact of density on the hydraulic properties of peat and the time domain reflectometry (TDR) moisture calibration curve
Authors: Shibchurn Anushka , Van Geel Paul J , Kennedy Paula L
Published: March 2005

The hydraulic properties of a peat used in a commercial peat biofilter were evaluated to determine their relationship with density and to establish a time domain reflectometry (TDR) calibration curve for water content as a function of the measured dielectric constant. The peat studied was a milled Sphagnum peat with a high organic content (99%). The dry densities evaluated in this study ranged from 90 to 180 kg/m3. The saturated hydraulic conductivity (Ks) decreased with an increase in dry density (ρdry) and was found to follow a log-linear relationship (Ks = 0.2462 exp(0.0438ρdry), correlation coefficient R2 = 0.9789). As expected, the soil moisture curve was impacted by density, with a higher density resulting in higher water contents for a given suction. The data were fit to the van Genuchten relationship. A TDR calibration curve was generated at five different densities. A comparison of the curves indicates that the water content as a function of dielectric constant was not dependent on density because of the significantly larger dielectric constant (Ka) of water compared with those of peat solids and air-filled voids. The TDR calibration curve for the peat evaluated in this study (volumetric water content Θv = 0.2667 ln(Ka)  0.1405, R2 = 0.9564) predicted higher water contents for a given dielectric constant compared with those from similar calibration curves for peat published in the literature. The data were compared with those from six other studies and indicated that the TDR calibration varied for different organic soils. The density-dependent hydraulic parameters and TDR calibration curve are important parameters needed to study the hydraulics of peat biofilters.Key words: peat, TDR, time domain reflectometry, density, hydraulics, soil moisture.
Seismic triggering of catastrophic failures on shear surfaces in saturated cohesionless soils
Authors: Trandafir Aurelian Catalin , Sassa Kyoji
Published: March 2005

This paper is concerned with an analysis of the seismic performance of infinite slopes in undrained conditions. The material assumed on the sliding surface is a loose saturated sand susceptible to a gradual loss in undrained shear strength after failure with the progress of unidirectional shear displacement. The undrained monotonic and cyclic shear behavior of this sand was investigated through an experimental study based on ring shear tests, with initial stresses corresponding to the static conditions on the sliding surface of the analyzed slopes. These tests provide the experimental framework for a modified sliding block method to estimate the earthquake-induced undrained shear displacements for conditions of no shear stress reversals on the sliding surface. The proposed estimation procedure incorporates the shearing resistance obtained from undrained monotonic ring shear tests to approximate the undrained yield resistance at a certain displacement during an earthquake. The term catastrophic failure is used in this study to define the accelerated motion of a potential sliding soil mass due to the static driving shear stress exceeding the reduced undrained yield resistance of the soil on the shear surface. The critical displacement necessary to trigger a catastrophic failure on the shear surface under seismic conditions was derived based on the shear resistance  shear displacement curve obtained under monotonic loading conditions. Using the shear resistance  shear displacement data from undrained monotonic ring shear tests and several processed horizontal earthquake accelerograms, the minimum peak earthquake acceleration necessary to cause a catastrophic shear failure under various seismic waveforms was estimated for conditions of no shear stress reversals on the sliding surface.Key words: earthquakes, slopes, critical shear displacement, sand, ring shear tests, undrained shear strength.
Thermally induced bark swelling in four North American tree species
Authors: Butler B W , Webb B W , Jimenez D , Reardon J A , Jones J L
Published: March 2005

Bark protects both the living phloem and the vascular cambium of trees. For some tree species the bark has been observed to swell in the radial direction when heated by nearby flames, possibly providing additional protection from thermal injury. In this study, detailed measurements of bark swelling (tumescence) are reported for four species: Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco), ponderosa pine (Pinus ponderosa Dougl. ex Laws.), chestnut oak (Quercus prinus L.), and red maple (Acer rubrum L.). Tests were conducted on over 574 samples extracted from 44 separate trees. The results clearly show that bark swelling occurs in the mature bark of Douglas-fir and to a lesser degree in chestnut oak. Ponderosa pine and red maple did not exhibit statistically significant swelling, but rather a modest decrease in overall bark thickness with heating. Significant swelling in Douglas-fir bark began at approximately 125 °C and resulted in a 15%80% increase in overall bark thickness. Swelling of chestnut oak was observed to begin at an average temperature of 225 °C and resulted in a 5%10% increase in total bark thickness. The increase in bark thickness occurred primarily in the radial direction in mature bark.
CONTROLLING CHAOS IN HIGHER-ORDER DYNAMICAL SYSTEMS
Authors: BOUKABOU ABDELKRIM , MANSOURI NORA
Published: March 2005

In this paper, we investigate a continuous extension of the Ott, Grebogi and Yorke control method [Ott et al., 1990]. This extension allows the control of chaotic behavior in higher-order dynamical systems. To begin with, studying the so-called Poincaré Sections (PS) enables determining fixed points and the effect of small changes in the control parameter on the system trajectory. Introduction of a stabilizer parameter in the control law keeps the dynamical properties and maintains them on a cyclic trajectory. The effectiveness of the proposed method is tested by numerical examples on the two typical Chen and Chua chaotic systems.
ALFVÉN CHAOTIC SADDLES
Authors: REMPEL E. L. , CHIAN A. C.-L.
Published: March 2005

We examine the dynamical roles of nonattracting chaotic sets known as chaotic saddles in an Alfvén wave system described by the driven-dissipative derivative nonlinear Schrödinger equation. These Alfvén chaotic saddles have gaps which are filled at the onset of chaos via a saddle-node bifurcation and at a chaotic transition via an interior crisis. It is shown that after an interior crisis an Alfvén chaotic attractor consists of two chaotic saddles connected by a set of coupling unstable periodic orbits.
A LIFE COURSE APPROACH TO CHRONIC DISEASE EPIDEMIOLOGY
Authors: Lynch John , Smith George Davey
Published: March 2005

▪ Abstract  A life course approach to chronic disease epidemiology uses a multidisciplinary framework to understand the importance of time and timing in associations between exposures and outcomes at the individual and population levels. Such an approach to chronic diseases is enriched by specification of the particular way that time and timing in relation to physical growth, reproduction, infection, social mobility, and behavioral transitions, etc., influence various adult chronic diseases in different ways, and more ambitiously, by how these temporal processes are interconnected and manifested in population-level disease trends. In this review, we discuss some historical background to life course epidemiology and theoretical models of life course processes, and we review some of the empirical evidence linking life course processes to coronary heart disease, hemorrhagic stroke, type II diabetes, breast cancer, and chronic obstructive pulmonary disease. We also underscore that a life course approach offers a way to conceptualize how underlying socio-environmental determinants of health, experienced at different life course stages, can differentially influence the development of chronic diseases, as mediated through proximal specific biological processes.
THE RISE AND FALL OF MENOPAUSAL HORMONE THERAPY
Authors: Barrett-Connor Elizabeth , Grady Deborah , Stefanick Marcia L.
Published: March 2005

▪ Abstract  Clinical trials show that hormone therapy (HT) is an effective treatment for vasomotor symptoms and vaginal dryness. HT improves other symptoms including sleep and quality of life in women who have menopause symptoms. In the Women's Health Initiative controlled clinical trials, both estrogen therapy (ET) and estrogen plus progestin therapy (EPT) reduced fracture risk, neither reduced the risk of heart disease, and both increased the risk of stroke, deep vein thrombosis, and dementia. EPT, but not ET, increased breast cancer risk and reduced colon cancer risk. Differences between EPT and ET may reflect chance, baseline differences between the EPT and ET cohorts, or a progestin effect. Studies of younger women and lower HT doses with intermediate endpoints are beginning.
Differential P1-purinergic modulation of human Schlemm's canal inner-wall cells
Authors: Karl Mike O. , Fleischhauer Johannes C. , Stamer W. Daniel , Peterson-Yantorno Kim , Mitchell Claire H. , Stone R. A. , Civan M. M.
Published: March 2005

Intraocular pressure is directly dependent on aqueous humor flow into, and resistance to flow out of, the eye. Adenosine has complex effects on intraocular pressure. Stimulation of A1 and A2A adenosine receptors changes intraocular pressure oppositely, likely through opposing actions on the outflow of aqueous humor. While the cellular sites regulating outflow resistance are unknown, the cells lining the inner wall of Schlemm's canal (SC) are a likely regulatory site. We applied selective adenosine receptor agonists to SC cells in vitro to compare the responses to A1 and A2A stimulation. Parallel studies were conducted with human inner-wall SC cells isolated by a novel enzyme-assisted technique and with cannula-derived mixed inner- and outer-wall SC cells. A1 agonists increased whole cell currents of both inner-wall and cannula-derived SC cells. An A2A agonist reduced currents most consistently in specifically inner-wall SC cells. Those currents were also increased by A2B, but not consistently affected by A3, stimulation. A1, A2A, and A3 agonists all increased SC-cell intracellular Ca2+. The electrophysiological results are consistent with the possibility that inner-wall SC cells may mediate the previously reported modulatory effects of adenosine on outflow resistance. The results are also consistent with the presence of functional A2B, as well as A1, A2A, and A3 adenosine receptors in SC cells.
Peroxisome proliferator-activated receptor-γ ligands regulate endothelial membrane superoxide production
Authors: Hwang Jinah , Kleinhenz Dean J. , Lassègue Bernard , Griendling Kathy K. , Dikalov Sergey , Hart C. Michael
Published: March 2005

Recently, we demonstrated that the peroxisome proliferator-activated receptor-γ (PPAR-γ) ligands, either 15-deoxy-Δ12,14-prostaglandin J2 (15d-PGJ2) or ciglitazone, increased endothelial nitric oxide (·NO) release without altering endothelial nitric oxide synthase (eNOS) expression ( 4 ). However, the precise molecular mechanisms of PPAR-γ-stimulated endothelial·NO release remain to be defined. Superoxide anion radical (O2−·) combines with ·NO to decrease·NO bioavailability. NADPH oxidase, which produces O2−·, and Cu/Zn-superoxide dismutase (Cu/Zn-SOD), which degrades O2−·, thereby contribute to regulation of endothelial cell·NO metabolism. Therefore, we examined the ability of PPAR-γ ligands to modulate endothelial O2−· metabolism through alterations in the expression and activity of NADPH oxidase or Cu/Zn-SOD. Treatment with 10 μM 15d-PGJ2 or ciglitazone for 24 h decreased human umbilical vein endothelial cell (HUVEC) membrane NADPH-dependent O2−· production detected with electron spin resonance spectroscopy. Treatment with 15d-PGJ2 or ciglitazone also reduced relative mRNA levels of the NADPH oxidase subunits, nox-1, gp91 phox (nox-2), and nox-4, as measured using real-time PCR analysis. Concordantly, Western blot analysis demonstrated that 15d-PGJ2 or ciglitazone decreased nox-2 and nox-4 protein expression. PPAR-γ ligands also stimulated both activity and expression of Cu/Zn-SOD in HUVEC. These data suggest that in addition to any direct effects on endothelial·NO production, PPAR-γ ligands enhance endothelial·NO bioavailability, in part by altering endothelial O2−· metabolism through suppression of NADPH oxidase and induction of Cu/Zn-SOD. These findings further elucidate the molecular mechanisms by which PPAR-γ ligands directly alter vascular endothelial function.
Skeletal muscle glycogen synthase subcellular localization: effects of insulin and PPAR-α agonist (K-111) administration in rhesus monkeys
Authors: Ortmeyer Heidi K. , Adall Yohannes , Marciani Karina R. , Katsiaras Andreas , Ryan Alice S. , Bodkin Noni L. , Hansen Barbara C.
Published: March 2005

Insulin covalently and allosterically regulates glycogen synthase (GS) and may also cause the translocation of GS from glycogen-poor to glycogen-rich locations. We examined the possible role of subcellular localization of GS and glycogen in insulin activation of GS in skeletal muscle of six obese monkeys and determined whether 1) insulin stimulation during a hyperinsulinemic euglycemic clamp and/or peroxisome proliferator-activated receptor (PPAR)-α agonist treatment (K-111, 3 mg·kg−1·day−1; Kowa) induced translocation of GS and 2) translocation of GS was associated with insulin activation of GS. GS and glycogen were present in all fractions obtained by differential centrifugation, except for the cytosolic fraction, under both basal and insulin-stimulated conditions. We found no evidence for translocation of GS by insulin. GS total (GST) activity was strongly associated with glycogen content ( r = 0.70, P < 0.001). Six weeks of treatment with K-111 increased GST activity in all fractions, except the cytosolic fraction, and mean GST activity, GS independent activity, and glycogen content were significantly higher in the insulin-stimulated samples compared with basal samples, effects not seen with vehicle. The increase in GST activity was strongly related to the increase in glycogen content during the hyperinsulinemic euglycemic clamp after K-111 administration ( r = 0.74, P < 0.001). Neither GS protein expression nor GS gene expression was affected by insulin or by K-111 treatment. We conclude that 1) in vivo insulin does not cause translocation of GS from a glycogen-poor to a glycogen-rich location in primate skeletal muscle and 2) the mechanism of action of K-111 to improve insulin sensitivity includes an increase in GST activity without an increase in GS gene or protein expression.
Insulin-Like Growth Factor I Levels in Healthy Adults
Authors: Landin-Wilhelmsen Kerstin , Lundberg Per-Arne , Lappas Georg , Wilhelmsen Lars
Published: March 2005

Insulin-like growth factor I (IGF-I) levels mainly reflect secretion of growth hormone (GH) in the body. The aims of this study were to compare different IGF-I assay methods in healthy individuals, test the reliability of the methods and discuss the utility of IGF-I measurement in adults. The Nichols Institute Diagnostics radioimmunoassay was used to evaluate IGF-I in two random population samples of men and women (aged 25–64 years, n = 392) taken 10 years apart, in 1985 and 1995. This method for IGF-I testing was also compared with an immunoradiometric assay (IRMA) method in 387 men and women participating in the World Health Organization MONICA (MONItoring of trends and determinants for CArdiovascular diseases) Project, Göteborg, Sweden, in 1995. Serum IGF-I decreased with increasing age in both men and women. IGF-I was higher in young women compared with young men in both cohorts, while the opposite was found in the highest age group. Age-adjusted significant correlations were found between IGF-I and smoking, fibrinogen, coffee consumption, lipoprotein (a), osteocalcin and IGF-binding protein 3. The two cohorts showed similar mean IGF-I concentrations irrespective of method. The correlation between the Nichols and the IRMA methods was high: r = 0.93 (p < 0.0001). Based on this and previous studies, population-based IGF-I measurements are robust irrespective of which commercially available method of assay is used. IGF-I levels can be used in diagnosing acromegaly as well as providing target values. IGF-I assay can be used as a complement to stimulation testing in the diagnosis of GH deficiency, and as a tool for GH dose titration.
Insulin-Like Growth Factor I Levels and the Diagnosis of Adult Growth Hormone Deficiency
Authors: Aimaretti Gianluca , Corneli Ginevra , Rovere Silvia , Granata Riccarda , Baldelli Roberto , Grottoli Silvia , Ghigo Ezio
Published: March 2005

The current guidelines state that, within the appropriate clinical context, the diagnosis of adult growth hormone (GH) deficiency must be made biochemically using provocative tests. Measurement of insulin-like growth factor I (IGF-I) and binding protein 3 (IGFBP-3) levels cannot always distinguish between healthy and GH-deficient individuals. In particular, IGFBP-3 as a marker of GH status is clearly less sensitive than IGF-I and there is general agreement that its measurement does not provide useful diagnostic information. However, the diagnostic value of measuring IGF-I levels has been revisited recently. It has been confirmed that normal IGF-I levels do not rule out severe GH deficiency (GHD) in adults, in whom the diagnosis has therefore to be based on the demonstration of severe impairment of the peak GH response to provocative tests. It has also been emphasized that very low IGF-I levels in patients with high suspicion of GHD could be considered to be definite evidence for severe GHD. This assumption particularly applies to patients with childhood-onset, severe GHD or with multiple hypopituitary deficiencies acquired in adulthood. In addition, the use of IGF-I levels to monitor the efficacy and adequacy of recombinant human GH replacement remains widely accepted.
The Role of Insulin-Like Growth Factor I Monitoring in Growth Hormone-Treated Children
Authors: Park Patricia , Cohen Pinchas
Published: March 2005

Growth hormone (GH) therapy has evolved rapidly over the past decade, and continuing research has established a clear role for therapeutic GH in a wide spectrum of disorders, including idiopathic GH deficiency (childhood- and adult-onset), Turner syndrome, Prader-Willi syndrome, small-for-gestational age children with failure of catch-up growth, AIDS-related catabolism, children with chronic renal failure, and idiopathic short stature. Although GH is used therapeutically in a wide variety of conditions, actual guidelines regarding the logistics of GH dosing continue to evolve, with data emerging regarding efficacy and safety. This review proposes a role for insulin-like growth factor I measurement in optimizing GH dosing.
Long-Term Monitoring of Insulin-Like Growth Factor I in Adult Growth Hormone Deficiency: A Critical Appraisal
Authors: Gibney James , Johannsson Gudmundur
Published: March 2005

Serum insulin-like growth factor I (IGF-I) levels predominantly reflect the hepatic effect of growth hormone (GH). Compared with serum GH levels, which reflect pulsatile GH secretion, serum IGF-I levels exhibit no major diurnal variation and thus provide a better estimate of integrated GH secretion in an individual patient. Measurement of serum IGF-I levels allows reliable identification of states of GH excess. In contrast, in a large proportion of adults with severe GH deficiency, serum IGF-I levels are within the normal range. Serum IGF-I levels increase markedly in response to GH administration and are often used as a surrogate variable for overall responsiveness to such treatment. Current data, however, suggest a poor relationship between changes in or levels of IGF-I and efficacy variables such as body composition, muscle function and well-being. The use of serum IGF-I as a guide during dose titration in the initial phase of treatment and during long-term monitoring of GH replacement therapy in adults, and its use as a safety marker or predictor of future morbidity and mortality are discussed here.
The Role of Insulin-Like Signalling in the Regulation of Ageing
Authors: Holzenberger M.
Published: March 2005

Inactivation of insulin-like growth factor I (IGF-I) signalling pathways have been shown to extend lifespans in various lower species, including the nematode Caenorhabditis elegans. In order to investigate this relationship in a mammalian species, a series of experiments were carried out with a mouse model heterozygous for a mutation in the IGF-I receptor gene. These heterozygous mice only had slight post-natal growth retardation, but had a lifespan 26% longer than normal. Their fertility and dietary intake were unaffected. The mechanism for increased lifespan in these mutant mice appears to be enhanced resistance to oxidative stress: heterozygous mice had a greater survival rate subsequent to severe oxidative stress generated in vivo than wild-type mice, and cells from heterozygous animals had a better resistance to hydrogen peroxide in vitro than cells from wild-type animals. Resistance to oxidative stress in these mutant animals could be caused by decreased phosphorylation of molecules downstream of the IGF-I receptor in the IGF-I signalling pathway, one of which is thought to be p66shc. Whether this link between reduced IGF-I signalling and longevity is conserved in other mammalian species, including humans, is presently not known. If it was, it could have implications for growth hormone therapy, which increases serum IGF-I levels.
Insulin-Like Growth Factor I and Impaired Glucose Tolerance
Authors: Dunger David , Yuen Kevin , Ong Ken
Published: March 2005

The effects of circulating insulin-like growth factor I (IGF-I) on glucose metabolism are well recognized. IGF-I is also important in maintaining β-cell mass and regulating endogenous growth hormone (GH) levels. Low IGF-I levels could explain links between small birth size and the risk of developing type 2 diabetes mellitus in short, obese adults. In a recent prospective study, childhood insulin secretion was related to IGF-I levels and statural growth, whereas insulin sensitivity was related to early post-natal weight gain. Common genetic polymorphisms in the IGF1 gene have been linked to small birth size, post-natal growth and future diabetes risk, but these results have been inconsistent. Recent adult studies have demonstrated that lower baseline IGF-I levels predict the subsequent development of impaired glucose tolerance (IGT), type 2 diabetes and cardiovascular disease. Administration of low-dose GH therapy, at a dose that minimizes the lipolytic effects of GH and has the ability to increase IGF-I levels, enhances insulin sensitivity in young healthy adults and in GH-deficient adults and increases insulin secretion in individuals with IGT. Whether the administration of low-dose GH, recombinant IGF-I or combined IGF-I/IGF-binding protein 3 therapy prevents future development of IGT or type 2 diabetes in high-risk normoglycaemic and GH-deficient individuals merits further long-term studies.
Glucocorticoid-Induced Osteoporosis: From Basic Mechanisms to Clinical Aspects
Authors: Alesci Salvatore , De Martino Massimo U. , Ilias Ioannis , Gold Philip W. , Chrousos George P.
Published: March 2005

Glucocorticoid (GC)-induced osteoporosis (GCOP) is the most common cause of osteoporosis in adults aged 20–45 years as well as the most common cause of iatrogenic osteoporosis. GC excess, either endogenous or exogenous, induces bone loss in 30–50% of cases. Indeed, bone loss leading to fractures is perhaps the most incapacitating, sometimes partially irreversible, complication of GC therapy. Nevertheless, GCOP is often underdiagnosed and left untreated. The following article provides an update on the cellular and molecular mechanisms implicated in the pathophysiology of GC-induced bone loss, as well as some guidelines on diagnostic, preventive and therapeutic strategies for this medical condition, in an effort to promote a better knowledge and greater awareness of GCOP by both the patient and the physician.
Rectal Distention Inhibits the Spinal Micturition Reflex via Glycinergic or GABAergic Mechanisms in Rats with Spinal Cord Injury
Authors: Miyazato Minoru , Sugaya Kimio , Nishijima Saori , Morozumi Makoto , Ohyama Choko , Ogawa Yoshihide
Published: March 2005

Background: We examined the influence of rectal distention on the spinal micturition reflex and the mechanism underlying its inhibition of bladder contraction. Methods: Fourteen conscious female Sprague-Dawley rats were used in this study after transection of the lower thoracic cord. Isovolumetric cystometry was performed before and after distention of the rectum by inflation of a rectal balloon, followed by intrathecal injection of strychnine (a selective glycine receptor antagonist) or bicuculline (a GABAA receptor antagonist) into the lumbosacral cord. Results: Rectal distention (1.0–3.0 cm3) prolonged the interval, decreased the amplitude, and shortened the duration of bladder contraction, and eventually almost abolished bladder activity. After intrathecal injection of strychnine (0.001–10 µg) or bicuculline (0.001–1 µg) in animals with inhibition of bladder activity by rectal distention, the interval, amplitude, and duration of bladder contraction returned to baseline. Conclusion: These results suggest that there is an inhibitory rectovesical reflex in the lumbosacral cord of rats with spinal cord injury, which modulates the spinal micturition reflex via glycinergic or GABAergic mechanisms.
Prostate Fossa Packing: A Simple, Quick and Effective Method of Achieving Hemostasis in Suprapubic Prostatectomy
Authors: Mireku-Boateng A.O. , Jackson Aaron G.
Published: March 2005

Introduction: Suprapubic prostatectomy remains a very common surgical treatment for bladder outlet obstruction from an enlarged prostate in the developing world. It is a technically simple procedure which can be learned by nonurologists who perform the bulk of these procedures in the developing world. Intraoperative and postoperative bleeding, however, can be a problem. We describe our experience with prostatic fossa packing at the time of the procedure, as a very simple, quick and effective technique for maximal hemostasis. Material and Methods: We have used this technique for several years at our institution and the results have been excellent. However, the major advantages of this technique became highlighted when the primary author visited Eritrea on a medical mission trip and used it in 42 consecutive cases. We looked at the hemorrhagic complications, both intraoperatively and postoperatively, infections and other complications related to the technique. Results: The 42 patients were typical of the patients that are seen in the developing world for suprapubic prostatectomy. The age range was 49–102 years. 75% had indwelling urethral catheters secondary to urinary retention. The duration of the catheters was from 2 weeks to 10 months. All the patients who had the indwelling catheters had bacteriuria. 56% had associated bladder calculi and 25% had associated inguinal hernias. The average surgical time was 45 min. The average intraoperative blood loss was estimated at 160 ml. There were no blood transfusions. There were no infections and there were no complications related to the packing. Conclusion: Packing of the prostatic fossa at the time of enucleation of the adenoma is a very simple, quick and effective way to achieve hemostasis in suprapubic prostatectomy. It is also very easy to learn. With this technique we have achieved zero rate of transfusion and no infections. The surgical time is also reduced. We have had no morbidities associated with this technique and highly recommend it.
Effect of ex vivo Gene Transfer with an Adenoviral Vector on Human Eye Bank Corneas
Authors: Thiel Michael A. , Saydam Celalettin , Pavlovic Jovan , Hemmi Silvio
Published: March 2005

Background: Ex vivo gene transfer to donor corneas using adenoviral vectors has gained increasing attention. This study investigates the effect of adenovirus-mediated gene transfer on endothelial cell (EC) count in human eye bank corneas. Methods: A replication-defective adenoviral vector containing the gene for green fluorescent protein was used to transduce organ-cultured normal human eye bank and porcine corneas. Transgene expression and EC count were assessed by light and fluorescence microscopy. Results: The transgene was expressed earlier by porcine EC (27% of all EC on day 2) than by human EC (6% on day 2), but the maximal number of EC finally expressing the transgene was higher in human than in porcine corneas (45 vs. 31% of all EC on day 12). Gene transfer caused considerably less EC loss in human than in porcine corneas (2 vs. 60% EC loss after 10 days). Conclusions: Adenoviral vectors for ex vivo gene transfer are more efficient and less toxic in normal human eye bank corneas than in porcine corneas, but human EC require more time until expression of transgenic proteins.
Molecular Analysis of RIM1 in Autosomal Recessive Retinitis pigmentosa
Authors: Barragan Isabel , Marcos Irene , Borrego Salud , Antiñolo Guillermo
Published: March 2005

Retinitis pigmentosa (RP) is a frequent retinal dystrophy characterized by a progressive loss of photoreceptors along with retinal degeneration. RIM1, encoding a presynaptic protein involved in the glutamate neurotransmission, is the responsible gene for autosomal dominant cone-rod dystrophy CORD7, whose locus overlaps partially with a locus of autosomal recessive RP (arRP), RP25. Given the genetic heterogeneity that features RP, it is plausible that mutations in RIM1 are also implicated in the disease in arRP families genetically linked to the CORD7 region. To test our hypothesis we analysed the complete RIM1 gene in 8 arRP families by DNA sequencing. Even though the absence of pathogenic mutations suggests that RIM1 is notinvolved in arRP, a role for this gene in other inherited forms of RP as well as other retinal dystrophies needs to be elucidated.
Comparison of in vitro Susceptibilities of Ocular Bacterial Isolates to Gatifloxacin and Other Topical Antibiotics
Authors: Kaliamurthy J. , Nelson Jesudasan C.A. , Geraldine P. , Parmar P. , Kalavathy C.M. , Thomas P.A.
Published: March 2005

Purpose: To compare the in vitro activity of gatifloxacin with that of other topical antibiotics against fresh bacterial isolates from various types of human ocular infections. Methods: A total of 498 strains of ocular bacterial isolates were tested for their susceptibility to gatifloxacin, ofloxacin, ciprofloxacin, norfloxacin, gentamicin, tobramycin, neomycin, chloramphenicol, erythromycin, tetracycline and amikacin. Results: Ninety-nine percent of gram-positive and 92% of gram-negative bacterial strains were found to be susceptible in vitro to gatifloxacin, whereas lower percentages of gram-positive and gram-negative bacteria were found to be susceptible to other antibiotics. Conclusions: In vitro, gatifloxacin exhibits good activity against various bacterial species isolated from different ocular sites. This requires corroboration in the clinical setting.
A Combination of Budesonide and the SH-Metabolite I of Erdosteine Acts Synergistically in Reducing Chemiluminescence during Human Neutrophil Respiratory Burst
Authors: Dal Sasso Monica , Culici Maria , Guffanti Enrico Eugenio , Bianchi Tiziana , Fonti Elena , Braga Pier Carlo
Published: March 2005

Activated neutrophils can release superoxide anion and nitric oxide (NO), which subsequently combine with each other to yield peroxynitrite anions, powerful and harmful oxidants that preferentially mediate the oxidation of the thiol groups in proteins and non-protein molecules. These oxidants play a direct role in the inflammatory process in chronic obstructive pulmonary disease and asthma by increasing the number of neutrophils and macrophages that induce a self-sustaining phlogogenic loop. Budesonide (BUD) and erdosteine (a muco-active drug which, after metabolization, produces an active metabolite (Met I) with a sulfhydryl group) are both active in reducing the release of superoxide anion, NO and peroxynitrite, and can be administered to patients with respiratory diseases. The aim of this study was to investigate the possible synergistic in vitro effect of BUD and Met I on chemiluminescence generation during fMLP-stimulated respiratory bursts of human neutrophils with the NO donor L-arginine, added to the incubating medium. The investigated BUD concentrations ranged from 6 × 10–8 to 1 × 10–6 mol/l in logarithmic scale and a significant and progressive reduction in luminol-amplified chemiluminescence (LACL) was observed at concentrations ranging from 2.5 × 10–7 to 1 × 10–6 mol/l. The investigated concentrations of Met I varied from 0.62 to 10 µg/ml. No significant changes were observed at 0.62, 1.25, and 2.5 µg/ml, but a significant decrease in LACL was observed at 5 and 10 µg/ml. When the two drugs were combined, there was a greater significant decrease in LACL versus the single drugs with the combinations of BUD 1 × 10–6 mol/l plus Met I 10 µg/ml, BUD 5 × 10–7 mol/l plus Met I 5 µg/ml, BUD 2.5 × 10–7 mol/l plus Met I 2.5 µg/ml, and BUD 1.25 × 10–7 mol/l plus Met I 1.25 µg/ml. A further interesting finding was that the combination of BUD 2.5 × 10–7 mol/l plus Met I 2.5 µg/ml and BUD 1.25 × 10–7 mol/l plus Met I 1.25 µg/ml significantly decreased LACL, whereas the single concentrations had no significant effect, thus indicating the possibility of extending the duration of the effect. Our findings indicate a synergistic antioxidant effect when BUD and Met I are given together, which is of interest for counteracting the airway phlogosis involved in many respiratory diseases.
Effectiveness of the Jaw-Thrust Maneuver in Opening the Airway: A Flexible Fiberoptic Endoscopic Study
Authors: Uzun Lokman , Ugur Mehmet Birol , Altunkaya Hanife , Ozer Yetkin , Ozkocak Isil , Demirel Cengiz Bekir
Published: March 2005

Objective: A prospective study was carried out to find the exact site of obstruction in sleep model and to quantitatively evaluate the effect of Jaw-thrust maneuver (JTM) in opening the obstructed airway using flexible fiberoptic endoscope. Methods: Twenty-eight ASA physical status I or II patients with snoring symptom undergoing elective surgery were included. The patients were held in supine position without hyperextension of the neck. Having induced anesthesia, the base of the tongue and laryngeal inlet and/or epiglottis were visualized using endoscope. The patients’ epiglottides were classified as leaf-shaped, curved (concaved or omega-shaped) and floppy types. We graded the airway opening at the level of epiglottis into six grades and obstruction at the tongue base level into four grades. The grades during inspiration (GrIns), expiration (GrExp) and after JTM (GrJTM) were recorded and compared with Pearson chi-square test. Results: The strictly curved (Ω-shaped or concaved) epiglottis supplied a salvage pathway for airflow that resisted collapsing with the posterior movement of the tongue base in 2 patients. When we compared GrIns with GrExp for epiglottis the difference was statistically significant (χ2 = 0.001), but the difference for tongue base was not (χ2 = 0.152). After JTM, GrJTM for both epiglottis and tongue base were significantly better than GrIns and GrExp (χ2 < 0.001). Conclusion: Tongue base was the principal site of obstruction although during the respiratory cycle the position of epiglottis changed prominently and increased the obstruction in inspiration. JTM alone significantly relieved the obstruction at the tongue base and epiglottis levels and increased the retroglossal airway.
Regulation of Apoptosis in External Auditory Canal Cholesteatoma by Hepatocyte Growth Factor/Scatter Factor
Authors: Naim Ramin , Shen Ted , Riedel Frank , Bran Gregor , Sadick Haneen , Hormann Karl
Published: March 2005

Objectives: External auditory canal cholesteatomas (EACC) are characterized by focal invasion of squamous cell epithelium and accumulation of keratin debris in the apical part of the matrix. Apoptosis appears to be important in understanding the pathogenesis of EACC. Here the possible regulatory effect of the apoptosis mediated by hepatocyte growth factor (HGF)/scatter factor (SF)-c-Met-Fas in EACC is dicussed. Methods: We examined 17 EACC specimens for immunohistochemical expression of HGF/SF, c-Met, caspase 3 and Fas. The staining reaction was evaluated semiquantitatively. Results: HGF/SF was detected in mesenchymal tissue below the EACC epithelium. c-Met was expressed throughout the epithelium. Fas and caspase 3 were detected at increasing levels towards the apical layers of the EACC matrix. Conclusions: High levels of HGF/SF result in binding of HGF/SF to c-Met, releasing Fas to aggregate and bind to its death-inducing signaling complex. The result is apoptosis, marked by formation of dead squamous cells and sequestered keratin debris on the apical side of the cholesteatoma.
Thalamocortical Connections in the Pond Turtle Pseudemys scripta elegans
Authors: Zhu Dantong , Lustig Kurt H. , Bifulco Katherine , Keifer Joyce
Published: March 2005

Thalamocortical connections are a neuroanatomical feature shared among vertebrates, although the extent and organization of these connections vary among species. From an evolutionary standpoint, reptiles represent early stages of the pattern of connectivity between the thalamus and cortex, and elucidation of these pathways may help to reveal the biological significance of these projections. The present tract tracing study was performed to examine the organization of thalamocortical projections in the pond turtle, Pseudemys scripta elegans. All experiments were carried out using in vitro brain preparations. Injections of neurobiotin into the medial cortex resulted in labeled neurons in the ipsilateral dorsomedial anterior nucleus of the thalamus, those in the dorsomedial cortex labeled neurons in the dorsolateral anterior nucleus, and injections into the dorsal cortex resulted in labeled neurons in the dorsal lateral geniculate nucleus of the thalamus. Injections of neurobiotin into these thalamic nuclei confirmed the projections to the cortex. Finally, neurobiotin injections primarily into the medial cortex resulted in bilateral label of axons and terminals in the suprapeduncular nucleus of the hypothalamus. The results of the neurobiotin injections revealed a topographic pattern of thalamocortical connections such that medial cortical regions connect with medial thalamic nuclei and lateral cortical regions connect with lateral nuclei. These findings suggest that the presence of functionally segregated thalamocortical projections is a conserved feature of brain organization among amniotes. Moreover, this work describes a descending pathway linking cortical regions with the red nucleus via the hypothalamus thereby providing indirect cortical control of the reptilian rubrospinal system.
Nasal Resistance in Patients with Obstructive Sleep Apnea
Authors: Li Hsueh-Yu , Wang Pa-Chun , Hsu Chung-Yao , Cheng Ming-lung , Liou Chin-Chia , Chen Ning-Hung
Published: March 2005

The aim of this study was to investigate the relationship between the severity of obstructive sleep apnea (OSA) and nasal resistance (NR). Eighty-five consecutive patients were recruited owing to their symptoms indicating OSA. All patients received polysomnography and anterior rhinomanometry (performed during wakefulness in the supine position). Patients were divided into low and high NR groups according to their rhinomanometric results; their polysomnographic, anthropometric and demographic data were compared. Correlation and regression analyses were conducted to investigate the associations between polysomnography and rhinomanometric measurements. The two studied groups were not different in body mass index, sex and age (p > 0.05), but the high NR group showed a significantly higher snoring index (p = 0.03). Furthermore, unilateral higher NR correlated significantly with respiratory disturbance index (r = 0.30, p = 0.006) and minimal oxygen saturation (r = –0.22, p = 0.04); total NR also correlated with the snoring index (r = 0.23, p = 0.04). Stepwise multivariate regression models revealed that unilateral higher NR was predictive of respiratory disturbance index (R2 = 0.087, p = 0.006). The research implied that NR is a possible contributing factor to snoring, with a need for further investigation to confirm the correlation between unilateral higher NR and the severity of OSA.
Connective Tissue Growth Factor Is Overexpressed in Complicated Atherosclerotic Plaques and Induces Mononuclear Cell Chemotaxis In Vitro
Authors: Cicha Iwona , Yilmaz Atilla , Klein Michael , Raithel Dieter , Brigstock David R. , Daniel Werner G. , Goppelt-Struebe Margarete , Garlichs Christoph D.
Published: March 2005

Objective—

Atherosclerotic blood vessels overexpress connective tissue growth factor (CTGF) mRNA, but the role of CTGF in atherosclerosis remains controversial. To assess the hypothesis that CTGF is involved in atherosclerotic plaque progression, we investigated CTGF protein expression and distribution in the different types of plaque morphology.

Methods and Results—

Serial cross-sections of 45 human carotid plaques were immunohistochemically analyzed for the presence of CTGF protein, neovascularization (von Willebrand factor), macrophages (CD68), and T cells (CD3). The lesions were categorized according to American Heart Association (AHA) classification as fibrous (type IV and V) or complicated plaques (type VI). The levels of CTGF were significantly higher in complicated compared with fibrous plaques (
P
=0.002). CTGF accumulated particularly in the rupture-prone plaque shoulder and in the areas of neovascularization or infiltration with inflammatory cells. Macrophage-like cells stained positive for CTGF protein in plaques. Subsequent in vitro studies showed that although monocyte-derived macrophages do not produce CTGF on stimulation with transforming growth factor-β, lipopolysaccharide, or thrombin, they take it up from culture medium. Furthermore, CTGF induces mononuclear cell chemotaxis in a dose-dependent manner.

Conclusion—

CTGF protein is significantly increased in complicated compared with fibrous plaques and may enhance monocyte migration into atherosclerotic lesions, thus contributing to atherogenesis.