bluuebunny/crossref_metadata_2025 huggingface dataset:
Fundamental Analysis of the Secondary Flows and Jet-Wake in a Torque Converter Pump—Part II: Flow in a Curved Stationary Passage and Combined Flows
Authors: Flack R. , Brun K.
Published: March 2005

Previously, experimental results for the velocity field in a torque converter pump showed strong jet/wake characteristics including backflows and circulatory secondary flows. Navier-Stokes flow models were developed herein to independently analyze the pump pressure-to-suction side jet/wake flow, the core-to-shell side jet/wake flow, and the secondary flows. Two relatively simple models were employed: (i) a rotating two-dimensional straight-walled duct and (ii) a 180 deg flow bend. Parametric studies were undertaken to evaluate the effect that operating conditions and geometry had on the characteristics. Results from the model showed that the core side wake, which was due to flow separation caused by rapid radial flow turning, was primarily a function of the Reynolds number; increasing the Reynolds number increased the core-to-shell side jet/wake flow. The passage length (or curvature) strongly affected the core-to-shell jet/wake. Using the modified equations for the generation of streamwise vorticity and the results from the two-dimensional jet/wake model for the normal and binormal vorticity components, trends for the secondary flows in the torque converter pump were predicted. Predicted secondary flows in the torque converter pump circulated in the counterclockwise direction (positive streamwise vorticity) in the pump midplane and in the clockwise direction (negative streamwise vorticity) in the pump exit plane. These trends agreed with experimental observations. Both the Reynolds number and the modified Rossby number were seen to have a significant influence on the streamwise vorticity and, thus, on the magnitude of the secondary flow velocities. The pump midplane counter-clockwise secondary flow circulation was primarily caused by the interaction of the pressure-to-suction side jet/wake nonuniform flow (and the associated normal vorticity component) with the high radial/axial flow turning angle the flow underwent while passing through blade passage. Similarly, the pump exit plane clockwise secondary flow circulation was caused by the core-to-shell side jet/wake nonuniform flow (and the associated binormal vorticity component) being rotated about a fixed centerline (pump shaft). Thus, the pump streamwise vorticity, which was responsible for the generation circulatory secondary flows, was directly related to the pump jet/wake phenomena.
A Review of the History of the National Advisory Committee for Aeronautics Centrifugal Compressor Program and Arrival at Current Computational Design Procedures
Authors: Hamrick Joseph T.
Published: March 2005

Before and during World War II, the design and development of single stage high pressure ratio centrifugal compressors was essentially a cut-and-try exercise. To reach a high pressure without substantial experimentation required multiple stages of impellers and diffusers with pressure ratios in the 2:1 range. While such arrangements were satisfactory for commercial use where weight was not a major consideration, they were not suitable for jet engines. The centrifugal compressor for the Whittle engine, the first British jet engine, was developed by trial and error with numerous modifications of the hub-shroud profile. The centrifugal compressor section of the National Advisory Committee for Aeronautics (NACA) designed, built, and tested three compressor impellers during and after World War II. They were part of a program designed to evaluate various blade shapes, but encountered such instabilities at the design pressure ratios that the experimental results led to no definitive conclusions. In 1948, the Centrifugal Compressor Section was given the assignment to further investigate the three impellers. The investigation led to the development of a quasi-three-dimensional design procedure that eliminated the guesswork from the basic design of a centrifugal impeller. Since the 1948 to 1955 time period over which the procedure was developed, the advances in computers have allowed refinements in the original computational methods. It is the objective of this presentation to review the history of the NACA centrifugal compressor program and efforts that have led to the latest developments in computational design procedures.
Natural Frequency Tuning Using Structural Patches
Authors: Wang P. W. , Cheng C. C.
Published: March 2005

A novel method for shifting the natural frequencies of a structure to specific values using structural patches is introduced. When a host structure is bonded with multiple structural patches, its natural frequencies can be shifted to the desired values by tuning the patch thickness and the patch location on the host structure. These parameters can be analytically determined using the methodology proposed in this paper. The time consuming process produced using the traditional optimal search method is thereby avoided. The results show that multiple natural frequencies can be changed simultaneously to the desired values. The number of natural frequencies shifted requires using the same number of structural patch pairs. Several examples using this technique are demonstrated and the results are experimentally validated.
Modeling and Experimental Methods for Dynamic Analysis of the Spaghetti Problem
Authors: Sugiyama Hiroyuki , Kobayashi Nobuyuki , Komaki Yoshimasa
Published: March 2005

The nonlinear dynamics of a very flexible body with time-variant length encompasses several industrial applications such as high-speed automatic coiling machines and copy machines. Among others, the significant increase in the vibration that occurs when the material length is shortened with time is known as the spaghetti problem. In this paper, the modeling method and the experimental procedure for the analysis of the spaghetti problem are presented. The change in the state of the forces and displacements at the boundary with a clearance is taken into consideration by modeling the mechanical interactions resulting from the clearance. A flexible beam is modeled using the finite segment method to account for the geometric nonlinearities due to the large rotation. The contact forces at the boundary are modeled using a set of springs and dampers. The numerical results obtained using the proposed modeling method agree well with the results obtained using the experiment. The effect of the transport velocity and the clearance are demonstrated, and the cause of the significant increase in the flexible body vibration is discussed from an energy balance viewpoint.
Contact Zone Force Profile and Machining Performance of Filamentary Brush1
Authors: Stango R. J. , Cariapa V. , Zuzanski M.
Published: March 2005

Filamentary brushing tools are used in a wide range of surface finishing processes, such as deburring, edge radiusing, polishing, and surface decontamination applications. Moreover, these tools are easily adapted to automation because the filament tips, which perform the machining operation, readily conform to the workpart surface without the need for sophisticated control systems technology. However, little is known about the material removal mechanics of filamentary brushes and, therefore, trial-and-error experimentation is often necessary before the tool is implemented in a production environment. This uncertainty of performance can be traced to a lack of understanding of the actual forces that are generated within the contact zone, that is, along the interface of the filament tip and workpart surface. Although previous experimental research has focused on the overall (i.e., resultant) brush force exerted onto the workpart, no information exists in the literature regarding the variation of force within the contact zone. Such information is essential for understanding the material removal profile within the contact zone, and could provide valuable information regarding the most active machining site along the contact surface. In this paper, a novel experiment is proposed for evaluating the force profile of filament tip forces that are generated within the contact region of a brushed surface. A specially designed workpart fixture is constructed and used in conjunction with a multiaxis force sensor for measuring the detailed force variation within the contact zone. The experiment is conducted using a wire brush at several different rotational speeds, which enables one to ascertain the role of filament inertia in the material removal process. Findings are reported which suggest that a significantly enhanced material removal rate can be achieved at a selective location within the contact zone at moderately elevated spindle speeds.
K-THEORETIC INVARIANTS AND CONFORMAL MEASURES OF THE DYCK SHIFTS
Authors: MATSUMOTO KENGO
Published: March 2005

The K-groups and the Bowen–Franks groups for subshifts are invariant under not only topological conjugacy but also flow equivalence. In this paper, the K-groups and the Bowen–Franks groups for the Dyck shift D2with 4 brackets are calculated. The spectrum of D2with bounded nonnegative eigenvectors is shown to be the singleton {3}. We then prove that a unique conformal probability measure on the right one-sided subshift XD2exists. These results are extended to general Dyck shifts DNwith 2N brackets.
CURRENT HARMONIC COMPENSATION USING PREDICTIVE CONTROLLERS
Authors: HAERI MOHAMMAD , KORDARI KAMIAR
Published: March 2005

The power quality has become a major concern since late 1980's. There has been increasing interest in studying power quality problems, one of which is the existence of the current/voltage harmonics. In order to eliminate these harmonics, different methods have so far been proposed and developed. In this paper, line current harmonics reduction is achieved by using an active filter. More specifically, our aim is to introduce a proper control design method for the current control part of the active filter. To achieve the goal, two different predictive controllers are examined. Due to the existing physical constraints (switching frequency and computational limits) in real applications, a new predictive control approach is proposed. The performance of this controller is compared to those obtained by two existing predictive controllers as well as commonly used PI controller through computer simulations considering various circumstances.
TEXTUAL-BASED CLUSTERING OF WEB DOCUMENTS
Authors: BRZEMINSKI PAWEL , PEDRYCZ WITOLD
Published: March 2005

In our study we presented an effective method for clustering of Web pages. From flat HTML files we extracted keywords, formed feature vectors as representation of Web pages and applied them to a clustering method. We took advantage of the Fuzzy C-Means clustering algorithm (FCM). We demonstrated an organized and schematic manner of data collection. Various categories of Web pages were retrieved from ODP (Open Directory Project) in order to create our datasets. The results of clustering proved that the method performs well for all datasets. Finally, we presented a comprehensive experimental study examining: the behavior of the algorithm for different input parameters, internal structure of datasets and classification experiments.
OUTCOME OF SURGERY IN PATIENTS WITH PAINFUL DORSAL WRIST GANGLIA AND ARTHROSCOPIC CONFIRMED LIGAMENT INJURY: A FIVE-YEAR FOLLOW-UP
Authors: Povlsen Bo , Tavakkolizadeh Adel
Published: March 2005

We report the outcome of a five-year follow-up after wrist arthroscopy and excision of painful dorsal wrist ganglia. The findings at the time of surgery have previously been published. Patients responded to a validated postal questionnaire regarding ganglion recurrence, wrist pain and function. None of the responding patients had recurrence of the ganglia since surgery but only one patient had remained pain free with normal function following surgery. Three of the remaining patients reported moderate to severe problems with work and four reported minimal work problems. Our findings suggest patients with arthroscopic confirmed ligament injuries leading to joint instability or localised osteoarthritis may develop functional disability but less severe injuries are unlikely to cause persistent problems in the short- to medium-term. Surgical excision of the ganglion can give lasting satisfactory cosmetic outcome despite persisting underlying ligament pathology.
TRAUMATIC EXTRUSION AND REPLACEMENT OF AUTOCLAVED DIAPHYSEAL SEGMENT OF RADIUS: A CASE REPORT
Authors: Rao Harish , Patil Sandeep R.
Published: March 2005

A 17-year-old patient had a traumatic extrusion of 10 cm distal radial segment. The segment of bone was replaced after cleaning and autoclaving. At four years follow-up, there was complete incorporation with almost full functional recovery. We report this case for its rarity and successful result.
RADIOCARPAL ARTHRODESIS FOR OSTEOARTHRITIS FOLLOWING FRACTURES OF THE DISTAL RADIUS
Authors: Yajima Hiroshi , Kobata Yasunori , Shigematsu Koji , Kawamura Kenji , Takakura Yoshinori
Published: March 2005

To compare the radioscapholunate (RSL) arthrodesis and radiolunate (RL) arthrodesis as a treatment for radiocarpal osteoarthritis following fractures of the distal radius, nine patients, 23 to 70 years old (average 41) at the time of surgery, were assessed two to 33 years after surgery. The periods between injury and surgery ranged from four months to 30 years. RSL arthrodesis was performed in three cases and RL arthrodesis in six. Post-operative wrist pain disappeared in six and was decreased in the other three. In the RSL group, the total arc of wrist flexion and extension was reduced from 50° pre-operatively to 35° post-operatively. In the RL group, it was increased from 72° to 76° after surgery. Grip strength improved in most patients, from 7 to 18 kg in the RSL group, and from 16 to 27 kg in the RL group. On roentogenogram, three patients showed arthritic changes in the adjacent joints, but there were no symptoms in two of the three patients. We concluded that partial radiocarpal arthrodesis (preferably RL arthrodesis) is a reliable procedure for radiocarpal osteoarthritis following fractures of the distal radius.
RADIOGRAPHIC MORPHOLOGY OF THE ULNAR HEAD
Authors: Hyams E. , Yazaki N. , Nakamura R. , Nakao E. , Watanabe K.
Published: March 2005

Posteroanterior radiographs of 102 normal wrists were studied to determine the morphological characteristics of the ulnar head associated with the value of ulnar variance. Ulnar variance, ulnar styloid length, ulnar head diameter, ulnar seat inclination, and the distance of ulnar head peak to the distal radioulnar joint were measured together with the third metacarpal length as a reference of the size of the wrist. Moderate correlation was confirmed not only between ulnar variance and ulnar seat inclination but also between ulnar variance and the distance of the ulnar head peak. Furthermore, we found a statistically significant correlation between ulnar variance and ulnar head diameter. The results showed that whole ulnar head configurations are affected by ulnar variance although there are considerable variations.
KIENBÖCK DISEASE TREATED BY EXCISIONAL ARTHROPLASTY WITH A PALMARIS LONGUS TENDON BALL: A COMPARATIVE STUDY OF CASES WITH OR WITHOUT BONE CORE
Authors: Sakai A. , Toba N. , Oshige T. , Menuki K. , Hirasawa H. , Nakamura T.
Published: March 2005

We hypothesised that using a palmaris longus tendon ball (PLTB) with bone core (w bc) after excisional arthroplasty for Kienböck disease would maintain post-operative carpal height compared to a PLTB without bone core (w/o bc). Seventeen hands of 16 consecutive patients with Kienböck disease at Lichtman stage IIIA or IIIB were treated by replacement of the lunate with a PLTB w bc or w/o bc. We evaluated the clinical and radiological outcomes at one, three and 12 months after surgery. According to Dornan and Lichtman criteria respectively, there were no significant differences between the two groups. In the w bc group, the post-operative values of the carpal height ratio (CHR) were maintained at the same level as pre-operative values for one year, while the post-operative CHR values in the w/o bc group were significantly lower than those in the w bc group. Our results indicate that in Kienböck disease, arthroplasty using a PLTB w bc can maintain CHR at one year after surgery compared to arthroplasty using a PLTB w/o bc.
A REMARK ON MONOTONIC CONVOLUTION
Authors: BERCOVICI H.
Published: March 2005

Muraki has shown that monotonic convolution of probability measures corresponds with composition of the reciprocal Cauchy transforms corresponding with these measures. We provide a new proof of this fact, not involving the combinatorics of moments.
apoE4 allele and the natural history of cardiovascular risk factors
Authors: Scuteri Angelo , Najjar Samer S. , Muller Denis , Andres Reubin , Morrell Christopher H. , Zonderman Alan B. , Lakatta Edward G.
Published: March 2005

The aims of the present study were to compare the longitudinal changes in traditional cardiovascular (CV) risk factors (blood pressure, BMI, total and HDL-cholesterol, triglycerides, and blood glucose) in men with and without the apolipoprotein (apo)E4 allele. Three hundred six men from the Baltimore Longitudinal Study of Aging, ranging in age from 20 to 92 yr, were studied. Repeated measurements of CV risk factors were performed over a median follow-up time of 7 yr (maximum 14.3 yr) for men. Longitudinal changes in these CV risk factors were analyzed by linear mixed-effects models. The prevalence of the apoE4 allele was 25.5%. apoE4 was independently associated with accelerated changes over time in fasting plasma glucose (+9.5% vs. no change in those without apoE4 in the 6th age-decade over 10 yr). No significant effect of apoE4 on longitudinal changes in total or HDL-cholesterol, triglycerides, or blood pressures was observed. In conclusion, apoE4 influences fasting plasma glucose and its changes over time. This could explain, in part, the increased CV risk associated with the apoE4 genotype observed in men.
Measurement of interstitial insulin in human adipose and muscle tissue under moderate hyperinsulinemia by means of direct interstitial access
Authors: Bodenlenz Manfred , Schaupp Lukas A. , Druml Tatjana , Sommer Romana , Wutte Andrea , Schaller Helga C. , Sinner Frank , Wach Paul , Pieber Thomas R.
Published: March 2005

Insulin’s action to stimulate glucose utilization is determined by the insulin concentration in interstitial fluid (ISF) of insulin-sensitive tissues. The concentration of interstitial insulin has been measured in human subcutaneous adipose tissue and skeletal muscle, however, never in parallel. The aim of this study was to compare interstitial insulin levels between both tissue beds by simultaneous measurements and to verify and quantify low peripheral ISF insulin fractions as found during moderate hyperinsulinemia. Nine healthy subjects (27.2 ± 0.8 yr) were investigated. A euglycemic-hyperinsulinemic clamp was started with a primed-constant intravenous insulin infusion of 1 mU·kg−1·min−1. For direct access to ISF, macroscopically perforated open-flow microperfusion catheters were inserted in both tissues. During steady-state conditions (9.5 h), interstitial effluents were collected in 30-min fractions using five different insulin concentrations in the inflowing perfusates (“no net flux” protocol). Regression analysis of insulin concentrations in perfusates and effluents yielded the relative recovery and the perfusate insulin concentration, which was in equilibrium with the surrounding tissue. Thus, in subcutaneous adipose tissue and skeletal muscle, the mean ISF-to-serum insulin level was calculated as 21.0% [95% confidence interval (CI) 17.5–24.5] and 26.0% (95% CI 19.1–32.8; P = 0.14), respectively. Recoveries for insulin averaged 51 and 64%, respectively. The data suggest that the concentrations of insulin arising in healthy subjects at the level of ISF per se are comparable between subcutaneous adipose and skeletal muscle tissue. The low interstitial insulin fractions seem to confirm reports of low peripheral insulin levels during moderate insulin clamps.
Age-dependent onset of liver-specific IGF-I gene deficiency and its persistence in old age: implications for postnatal growth and insulin resistance in LID mice
Authors: Tang Zhengyi , Yu Rong , Lu Yarong , Parlow A. F. , Liu Jun-Li
Published: March 2005

To explore the limitations of the liver-specific IGF-I gene-deficient (LID) model and to further evaluate the role of endocrine IGF-I in early postnatal life and old age, we have studied these mice during the prepubertal period (from birth to 3 wk of age) and when they are 2 yr old. During the first 2 wk of life, IGF-I gene deficiency and the resulting reduction in serum IGF-I levels in LID mice did not reach sufficiently low levels when mice experience the most rapid and growth hormone (GH)-independent growth. It suggests that the role of liver-derived IGF-I in prepubertal, GH-independent postnatal growth cannot be established. From our previous studies, liver IGF-I mRNA level was abolished in adult LID mice, which causes elevated GH level, insulin resistance, pancreatic islet enlargement, and hyperinsulinemia. Interestingly in 2-yr-old LID mice, although liver IGF-I mRNA and serum IGF-I levels were still suppressed, serum insulin and GH levels had returned to normal. Compared with same-sex control littermates, aged male LID mice had significantly reduced body weight and fat mass and exhibited normal insulin sensitivity. On the other hand, aged female LID mice exhibited normal weight and marginal resistance to insulin actions. The pancreatic islet percentage (reflecting islet cell mass) was also restored to normal levels in aged LID mice. Thus, although the IGF-I gene deficiency is well maintained into old age, the insulin sensitivity, islet enlargement, and hyperinsulinemia that occurred in young adult mice have been mostly restored to normal levels, further supporting the age-dependent and sexual dimorphic features of the LID mice.
Involvement of mitogen-activated protein kinases in adriamycin-induced cardiomyopathy
Authors: Lou H. , Danelisen I. , Singal P. K.
Published: March 2005

The current study investigated the phosphorylation of mitogen-activated protein kinases (MAPKs) as well as pro- and anti-apoptotic proteins in adriamycin (ADR)-induced cardiomyopathy (AIC) and heart failure in rats. Modulatory effects of antioxidant probucol on the activation of MAPKs were also examined. Male rats were administered with ADR (15 mg/kg body wt ip, over 2 wk) with and without probucol (120 mg/kg body wt for 4 wk ip). Hearts from these animals were studied at 1- to 24-h as well as at 3-wk posttreatment durations. In the 3-wk group, ADR depressed cardiac function, increased left ventricular end-diastolic pressure (LVEDP), and caused dyspnea and mortality. These changes were prevented by probucol. Phosphorylation of extracellular signal-regulated kinase (ERK)1/2, in the early stage of AIC, showed a biphasic response, with a maximum increase to 513% seen at 4 h, followed by a decrease to 66.8% at 3 wk after the last injection of ADR. Phosphorylation of p38 and c-Jun NH2-terminal kinases (JNKs) showed a steady increase through 2, 4, and 24 h and 3 wk (116% to 148%). In gene microarray analysis at 3 wk (heart failure stage), mRNA expression for both ERK1/2 and p38 kinases was decreased, whereas JNK mRNA was undetectable. Probucol completely prevented these MAPK changes. Activation of caspase-3 as well as the increase in the ratio of Bax to Bcl-xl were seen at early time points (1–24 h) as well as in the heart failure stage (3 wk). It is suggested that a transient increase in ERK1/2 at a shorter interval indicate an early adaptive response, and failure of this response corresponded with heart failure. In contrast, a gradual and persistent increase in p38 and JNK MAPKs as well as in caspase-3 and the Bax-to-Bcl-xl ratio may contribute in the initiation of apoptosis and progression of heart failure. Because probucol modulated changes in cellular signaling pathways and cardiac function, it is likely that oxidative stress plays a key role in AIC and heart failure.
Vigorous exercise acutely changes platelet and B-lymphocyte CD39 expression
Authors: Coppola Antonino , Coppola Ludovico , dalla Mora Liliana , Limongelli Francesco M. , Grassia Antonio , Mastrolorenzo Luigia , Gombos Giorgio , Lucivero Giacomo
Published: March 2005

CD39/ATP diphosphohydrolase is expressed on B lymphocytes, cytotoxic T lymphocytes, monocytes, platelets, and endothelial cells, and it has a critical role in the inhibition of platelet responsiveness. To determine whether strenuous exercise could acutely change expression of CD39 in platelets and lymphocytes, eight healthy sedentary men, 34 yr old (SD 7), and eight physically active men, 34 yr old (SD 6), performed graded upright cycle ergometry to volitional exhaustion. Blood samples collected both at baseline and after exercise test were employed to measure CD39 expression in platelets and lymphocytes. The percentage of circulating platelet-platelet aggregates, the “in vitro” ADP and collagen-induced platelet aggregation, and the expression of both platelet glycoprotein IIb-IIIa (PAC-1) and P-selectin (CD62) were also considered markers of platelet activation. After strenuous exercise, all subjects demonstrated significant platelet activation as judged by the increased percentage of platelet-platelet aggregates. The in vitro ADP-induced platelet aggregation and the expression of CD62P on ADP-stimulated platelets significantly increased in sedentary but not in active subjects. After exercise, all of the subjects showed a significant reduction of CD39 expression in platelet [sedentary: from 2.2 (SD 0.8) to 1.1% (SD 0.8), P = 0.008; active: from 0.6 (SD 0.2) to 0.35% (SD 0.1), P = 0.009] and an increase of CD39 expression in B lymphocytes [sedentary: from 47 (SD 13) to 60% (SD 11), P = 0.0039; active: from 46 (SD 11) to 59% (SD 11), P = 0.0038]. Taken together, these findings confirm the critical role of this ADPase in inhibition of platelet responsiveness, also suggesting a possible role of B lymphocytes in thromboregulation mechanism.
Effect of acute hypoxia on microcirculatory and tissue oxygen levels in rat cremaster muscle
Authors: Johnson Paul C. , Vandegriff Kim , Tsai Amy G. , Intaglietta Marcos
Published: March 2005

Repeated exposure to brief periods of hypoxia leads to pathophysiological changes in experimental animals similar to those seen in sleep apnea. To determine the effects of such exposure on oxygen levels in vivo, we used an optical method to measure Po2in microcirculatory vessels and tissue of the rat cremaster muscle during a 1-min step reduction of inspired oxygen fraction from 0.21 to 0.07. Under control conditions, Po2was 98.1 ± 1.9 Torr in arterial blood, 52.2 ± 2.8 Torr in 29.0 ± 2.7-μm arterioles, 26.8 ± 1.7 Torr in the tissue interstitium near venous capillaries, and 35.1 ± 2.6 Torr in 29.7 ± 1.9-μm venules. The initial fall in Po2during hypoxia was significantly greater in arterial blood, being 93% complete in the first 10 s, whereas it was 68% complete in arterioles, 47% at the tissue sites, and 38% in venules. In the 10- to 30-s period, the fall in normalized tissue and venular Po2was significantly greater than in arterial Po2. At the end of hypoxic exposure, Po2at all measurement sites had fallen very nearly in proportion to that in the inspired gas, but tissue oxygen levels did not reach critical Po2. Significant differences in oxyhemoglobin desaturation rate were also observed between arterial and microcirculatory vessels during hypoxia. In conclusion, the fall in microcirculatory and tissue oxygen levels in resting skeletal muscle is significantly slower than in arterial blood during a step reduction to an inspired oxygen fraction of 0.07, and tissue Po2does not reach anaerobic levels.
Cell type-specific response to growth on soft materials
Authors: Georges Penelope C. , Janmey Paul A.
Published: March 2005

Many cell types respond to forces as acutely as they do to chemical stimuli, but the mechanisms by which cells sense mechanical stimuli and how these factors alter cellular structure and function in vivo are far less explored than those triggered by chemical ligands. Forces arise both from effects outside the cell and from mechanochemical reactions within the cell that generate stresses on the surface to which the cells adhere. Several recent reviews have summarized how externally applied forces may trigger a cellular response (Silver FH and Siperko LM. Crit Rev Biomed Eng 31: 255–331, 2003; Estes BT, Gimble JM, and Guilak F. Curr Top Dev Biol 60: 91–126, 2004; Janmey PA and Weitz DA. Trends Biochem Sci 29: 364–370, 2004). The purpose of this review is to examine the information available in the current literature describing the relationship between a cell and the rigidity of the matrix on which it resides. We will review recent studies and techniques that focus on substrate compliance as a major variable in cell culture studies. We will discuss the specificity of cell response to stiffness and discuss how this may be important in particular tissue systems. We will attempt to link the mechanoresponse to real pathological states and speculate on the possible biological significance of mechanosensing.
How Does the Kidney Filter Plasma?
Authors: Tryggvason Karl , Wartiovaara Jorma
Published: March 2005

The kidneys filter the plasma in special filtration units—glomeruli—and thereby excrete low-molecular-weight waste products into the urine. The mechanisms of glomerular filtration have been a matter of controversy for several decades, but recent data have revealed new details about the molecular nature of the filter and have demonstrated a central role for the podocyte slit diaphragm in the filtration process.
The Genetics of Heteromeric Amino Acid Transporters
Authors: Palacín Manuel , Nunes Virginia , Font-Llitjós Mariona , Jiménez-Vidal Maite , Fort Joana , Gasol Emma , Pineda Marta , Feliubadaló Lidia , Chillarón Josep , Zorzano Antonio
Published: March 2005

Heteromeric amino acid transporters (HATs) are composed of a heavy ( SLC3 family) and a light ( SLC7 family) subunit. Mutations in system b0,+(rBAT-b0,+AT) and in system y+L (4F2hc-y+LAT1) cause the primary inherited aminoacidurias (PIAs) cystinuria and lysinuric protein intolerance, respectively. Recent developments [including the identification of the first Hartnup disorder gene (B0AT1; SLC6A19)] and knockout mouse models have begun to reveal the basis of renal and intestinal reabsorption of amino acids in mammals.
DNA Diagnosis of Single Gene Disorders in Patients of Non-European Origin: Experience from Kuwait
Authors: Samilchuk E.
Published: March 2005

Objective: The aim of this study was to establish genetic DNA-diagnostic service in Kuwait. Methods: Polymerase chain reaction, restriction fragment length polymorphisms, heteroduplex analysis and DNA sequencing were applied. Results: Direct testing for common mutations had variable success in Kuwaiti patients with different genetic disorders, and additional mutation analysis was required in many cases. Genetic heterogeneity, mutations of Mediterranean, African and Arabic/Middle Eastern origin, and homozygosity by descent are characteristic of patients from Kuwait. Conclusions: More efforts aimed at the identification of mutations underlying genetic disorders in Kuwait as well as in other Gulf countries are warranted. This can be achieved by focusing genetic research in the academic institutions of Gulf countries towards this goal.
Familial Predictors of Childhood Shyness: A Study of the United Arab Emirates Population
Authors: Eapen V. , Ghubash R. , Salem M.O. , Sabri S.
Published: March 2005

Objectives: Phobic anxiety disorders generally breed true. In this regard, family studies have suggested an association between childhood shyness and maternal social phobia. In this study, the relationship between childhood shyness and maternal social anxiety was examined. Subjects andMethods: 203 5-year-old children from an Arabian Gulf community and their mothers were evaluated. The children were assessed in stage 1 using the shyness scale of Stevenson-Hinde and Glover and the Preschool Behavior Checklist (PBCL), while mothers completed the Liebowitz Social Anxiety Scale. In the second stage, blind clinical interviews were carried out to ascertain the diagnosis of psychiatric diagnoses, if any, using DSM-IV criteria. Results: 27% of the children were identified as shy using the shyness scale of Stevenson-Hinde and Glover and 19% scored above the cutoff for behavioral disturbance on the PBCL. Child shyness was associated with female gender and maternal social anxiety as indicated by scores on the Liebowitz Social Anxiety Scale, while an inverse relationship was noted with behavioral disturbance. The odds of the child having a high shyness score was increased if the mother had social anxiety (odds ratio = 2.14) and the child lived in a family that was ‘not socially active’ (odds ratio = 1.42). Conclusion: Our initial findings suggest that there may be a complex interaction between maternal social anxiety and family sociability in childhood shyness. Prospective longitudinal work is indicated.
Dermal Capillary Clearance: Physiology and Modeling
Authors: Kretsos K. , Kasting G.B.
Published: March 2005

Substances applied to the skin surface may permeate deeper tissue layers and pass into the body’s systemic circulation by entering blood or lymphatic vessels in the dermis. The purpose of this review is an in-depth analysis of the dermal clearance/exchange process and its constituents: transport through the interstitium, permeability of the microvascular barrier and removal via the circulation. We adapt an ‘engineering’ viewpoint with emphasis on quantifying the dermal microcirculatory physiology, providing the theoretical framework for the physics of key transport processes and reviewing the available computational clearance models in a comparative manner. Selected experimental data which may serve as valuable input to modeling attempts are also reported.
Corneofungimetry Bioassay on Malassezia spp. under Ketoconazole and Desonide Influences
Authors: Piérard-Franchimont C. , Vroome V. , Cauwenbergh G. , Piérard G.E.
Published: March 2005

Background: Glucocorticoids can boost some Malassezia-driven dermatoses. However, both antifungals and topical corticosteroids improve lesions of seborrheic dermatitis. Objective: To revisit the topical activity of the antifungal ketoconazole and the corticosteroid desonide on Malassezia growth on human stratum corneum. Material and Methods: The computer-assisted corneofungimetry bioassay was used to compare the growth of M. furfur, M. globosa and M. restricta on human stratum corneum coated with olive oil. Four blinded gel formulations were tested. They contained either 2% ketoconazole, 0.05% desonide or a combination of 2% ketoconazole and 0.05% desonide; one gel was unmedicated. Untreated stratum corneum and specimens coated with a 2% ketoconazole cream were used as negative and positive comparators, respectively. A total of 45 samples (15 M. furfur, 15 M. globosa, and 15 M. restricta) were used for each test formulation in this randomized, double-blind study. Results: The 2% ketoconazole gel and cream and the combination of 2% ketoconazole and 0.05% desonide formulation abated similarly and significantly the M. furfur, M. globosa and M. restricta growth. The 3 species were similarly sensitive to these formulations. By contrast, no significant inhibitory effect was yielded by the 0.05% desonide gel and the vehicle. Conclusion: The presence of 0.05% desonide does not impair or improve the Malassezia susceptibility to 2% ketoconazole when growing on lipid-enriched human stratum corneum.
Calcium Loading, Calcium Accumulation, and Associated Cardiovascular Risks in Dialysis Patients
Authors: Klemmer Philip J.
Published: March 2005

Calcium and phosphate imbalances are important mutable risk factors for cardiovascular disease in chronic kidney disease (CKD). Nearly all dialysis patients require phosphate binders. These include traditional calcium-based compounds and, more recently, the calcium-free, metal-free, non-absorbed agent, sevelamer hydrochloride. Both binder types reduce serum phosphorus, but differ with respect to calcium load and metabolism. Absorption from calcium-based agents very likely promotes positive total calcium balance in many patients. Positive calcium balance is inappropriate in adults and may promote or accelerate soft-tissue and vascular calcification even in the absence of hypercalcemia. Calcium accumulation in heart and vascular tissues contributes to rapidly progressive cardiovascular calcification – a strong predictor of cardiovascular and all-cause mortality in stage 5 CKD. More than two-thirds of stage 5 CKD patients have calcification scores above the 75th percentile for matched controls – scores associated with extremely high risk of cardiovascular events and death.
Blood Component Transfusion in Primary Coronary Artery Bypass Surgery in Kuwait
Authors: Al-Shammari Fahad , Al-Duaij Ahmed , Al-Fadhli Jamal , Al-Sahwaf Emad , Tarazi Riyad
Published: March 2005

Objective: The aims of this study were to determine the rate of blood product transfusion, associated perioperative factors and cost of such blood product transfusion in primary coronary artery bypass surgery (CABG). Subjects and Methods:The medical records of 159 consecutive primary CABG patients (142 male, 17 female) from January 1, 2003 to June 30, 2003 at Chest Diseases Hospital, Kuwait, were reviewed. Urgent and emergency cases were included. Results: The mean age of the patients was 57.2 (range 36–77 years). Overall, 128 (80.5%) patients received blood product transfusion during primary CABG: 113 (70.5%) packed red blood cells (RBC), 54 (33.9%) fresh frozen plasma, and 13 (8%) platelets. Overall, 23 patients (12.6%) received more than two RBC transfusions intraoperatively. Significant factors for intraoperative RBC transfusion were: age >60 years, female gender, preoperative hemoglobin <12 g/dl, and 3 or more coronary bypass grafts constructed. One hundred and fifty-nine patients consumed 342 units of RBC at an average of 2.1 RBC units per patient. The cost per patient was 80 Kuwaiti dinar (KD; USD 240). Conclusion:The findings indicate a high rate of blood component transfusion in primary CABG patients in Kuwait that could expose the patients to the possible adverse effects, and such transfusions have high economic impact.
Prevalence of Type 1 Diabetes among 6- to 18-Year-Old Kuwaiti Children
Authors: Moussa Mohamed A.A. , Alsaeid Mayra , Abdella Nabila , Refai Thanaa M.K. , Al-Sheikh Nashami , Gomez Joseph E.
Published: March 2005

Objectives: To determine the prevalence of type 1 diabetes among 6- to 18-year-old Kuwaiti children according to gender, age, and region. Subjects and Methods: Children with type 1 diabetes aged 6–18 years were identified at 182 schools (50 primary, 63 intermediate, and 69 secondary) in Kuwait during the study period October 2000 to September 2002. Schools were randomly selected using the 2000/01 educational districts’ registers as sampling frame proportional to the number of schools in each district. Prevalence rates were adjusted to the 2002 Kuwaiti population. Diagnosis of type 1 diabetes was based on the World Health Organization, and the American Diabetes Association criteria. Results: Prevalence of type 1 diabetes was 269.9 per 100,000 (95% confidence interval, CI 241.6–298.3). There was no significant difference in prevalence between male (247.6, 95% CI 205.2–290.0) and female (285.5, 95% CI 247.5–323.5). Type 1 diabetes was more prevalent in the age group 10–13 years (347.3), and lowest in the age group 6–9 years (182.6) per 100,000; the difference was significant at p < 0.001. The overall age-adjusted prevalence rate was 252.9 (95% CI 234.6–271.2), 229.1 (95% CI 204.6–253.6) in male and 277.4 (95% CI 250.0–304.7) in female children in the 2002 Kuwaiti population. The mean age at onset was 9.2, and 8.1 years in male and female children, respectively (p = 0.018). There was no significant difference in prevalence between regions. Conclusion: Type 1 diabetes is a common chronic disease in Kuwaiti children.
Effect of Indomethacin on the Hypercapnia-Associated Vasodilation of the Optic Nerve Head Vessels: An Experimental Study in Miniature Pigs
Authors: Petropoulos Ioannis K. , Pournaras Constantin J.
Published: March 2005

Purpose: To evaluate whether prostaglandins are mediators of the hypercapnia-associated vasodilation of the optic nerve head vessels. Methods: We measured the PO2 at intervascular areas of the optic disc in 9 anaesthetized miniature pigs using oxygen-sensitive microelectrodes placed at <50 µm from the optic disc. PO2 was measured continuously under normoxia, hyperoxia (breathing of 100% O2), carbogen breathing (95% O2, 5% CO2), and hypercapnia (40% increase in inhaled CO2). Similar measurements under these conditions were also done after intravenous administration of the prostaglandin inhibitor indomethacin. Results: Before the injection of indomethacin, we observed a slight increase in the optic disc PO2 during hypercapnia (ΔPO2 = 2.0 ± 1.7 mm Hg; p < 0.001; n = 18) or hyperoxia (ΔPO2 = 3.4 ± 1.6 mm Hg; p < 0.001; n = 23), but a much more important increase during carbogen breathing (ΔPO2 = 12.0 ± 5.1 mm Hg; p < 0.001; n = 23). After the injection of indomethacin, the increase in the optic disc PO2 was similar during hyperoxia (ΔPO2 = 5.6 ± 2.2 mm Hg; p < 0.001; n = 9) or carbogen breathing (ΔPO2 = 5.8 ± 3.2 mm Hg; p < 0.001; n = 9), while in hypercapnia the variation of the optic disc PO2 was minimal (ΔPO2 = 0.5 ± 1.9 mm Hg; p > 0.1; n = 6). Conclusions: Indomethacin inhibits the vasodilatory effect of increased systemic PaCO2 on the optic nerve head vessels, leading to a similar moderate increase in the optic disc PO2 during carbogen breathing as in hyperoxia. Indomethacin also inhibits the increase in the optic disc PO2 seen during hypercapnia. Those results indicate that prostaglandins are mediators of the hypercapnia-associated vasodilation of the optic nerve head vessels.
In vitro Activity of Levofloxacin against Recent Gram-Negative Nosocomial Pathogens
Authors: Lanzafame Agata , Bonfiglio Giovanni , Santini Luca , Mattina Roberto
Published: March 2005

The objective of our study was to evaluate the in vitro activity of levofloxacin in comparison with other antibiotics (coamoxiclav, ceftriaxone, ceftazidime, meropenem, aztreonam, ciprofloxacin and netilmicin) against about 500 Gram-negative nosocomial microorganisms, isolated during 2003. The bactericidal activities (minimal bactericidal activity and killing curve) of levofloxacin and the other antibiotics were also evaluated. The results confirm the excellent in vitro activity of levofloxacin against multiresistant nosocomial Gram-negative pathogens, including the 73 extended spectrum β-lactamase producer strains (90% of Escherichia coli, Enterobacter cloacae and Klebsiella pneumoniae were inhibited at 0.5 mg/l). Of particular interest is its susceptibility and bactericidal activity against Stenotrophomonas maltophilia strains. In conclusion, due to the favorable pharmacokinetics and pharmacodynamics of the molecule, associated with its safety, levofloxacin may represent a valid therapeutic option in the treatment of severe Gram-negative nosocomial infections.
Nutritional and Inflammatory Markers in the Prediction of Mortality in Chinese Hemodialysis Patients
Authors: Hung Chung-Ying , Chen Yi-Ann , Chou Chia-Chi , Yang Chwei-Shiun
Published: March 2005

Background/Aims: The prevalence ofcardiovascular disease and mortality rate is relatively low in Chinese dialysis patients. This study aimed to evaluate the predictive value of nutritional and inflammatory markers in Chinese hemodialysis patients. Methods: A total of 158 patients (70 men and 88 women, age 59.9 ± 13.2 years) were studied. Nutritional and inflammatory markers, including subjective global assessment (SGA), insulin-like growth factor-1, albumin, tumor necrosis factor-α, interleukin (IL)-1β, IL-6, serum amyloid A (SAA), and C-reactive protein (CRP), were measured. These patients were followed up until April 2004 (36 months) to determine the incidence and causes of death. Results: SGA (p = 0.001), IL-1β (p = 0.032), SAA (p = 0.031), IL-6 (p = 0.001) and CRP (p < 0.001) were found to be significant predictors of mortality. After adjusting with age, sex, diabetes, coronary artery disease, Kt/Vurea, and duration on dialysis, CRP (odds ratio = 4.58; p = 0.038) and SGA (odds ratio = 6.57; p = 0.004) remained the independent predictors of mortality. The adjusted mortality rate was highest for patients with a high CRP level and malnutrition (assessed by SGA). Conclusions: SGA and CRP levels are the most significant predictors of mortality in Chinese dialysis patients. Chinese dialysis patients with a high CRP level tend to be at higher risk of mortality only if they are malnourished.
All-trans-Retinoic Acid Inhibits the Development of Mesangial Proliferative Glomerulonephritis in Interleukin-6 Transgenic Mice
Authors: Shima Yoshihito , Iwano Masayuki , Yoshizaki Kazuyuki , Tanaka Toshio , Kawase Ichiro , Nishimoto Norihiro
Published: March 2005

All-trans-retinoic acid (ATRA), a vitamin A derivative, was reported to suppress the interleukin-6 (IL-6) production and to downregulate the IL-6 receptor (IL-6R) and/or its signal transducer glycoprotein 130. We investigated the in vivo antinephritic effect of ATRA on IL-6 transgenic mice which had developed mesangial proliferative glomerulonephritis (PGN) as well as its in vitro inhibitory effect on the proliferation of rat mesangial cells. In vivo experiments on IL-6 transgenic mice showed that ATRA administration suppressed proteinuria and hematuria and reduced the IL-6 concentrations; furthermore, histological examination demonstrated that it improved PGN. In vitro experiments using rat mesangial cells demonstrated that ATRA inhibited cell growth in a dose-dependent manner within a range from 10–4 to 10–6M. This inhibition by ATRA was partially counteracted by the addition of IL-6. RT-PCR assay results showed that ATRA also reduced IL-6R, but not the glycoprotein 130 expression in mesangial cells. These findings indicate that, by blocking of the IL-6 function, ATRA may be therapeutically effective in PGN.
Variability of Drop Size Distributions: Time-Scale Dependence of the Variability and Its Effects on Rain Estimation
Authors: Lee Gyu Won , Zawadzki Isztar
Published: March 2005

A systematic and intensive analysis is performed on 5 yr of reliable disdrometric data (over 20 000 one-minute drop size distributions, DSDs) to investigate the variability of DSDs in the Montreal, Quebec, Canada, area. The scale dependence (climatological scale, day to day, within a day, between physical processes, and within a physical process) of the DSD variability and its effect on rainfall intensity R estimation from radar reflectivity Z are explored in terms of bias and random errors. Detail error distributions are also provided. The use of a climatological R–Z relationship for rainfall—affected by all of the DSDs’ variability—leads on average to a random error of 41% in instantaneous rain-rate estimation. This error decreases with integration time, but the decrease becomes less pronounced for integration times longer than 2 h. Daily accumulations computed with the climatological R–Z relationship have a bias of 28% because of the day-to-day DSD variability. However, when daily R–Z relationships are used, a random error of 32% in instantaneous rain rate is still present because of the DSD variability within a day. This illustrates that most of the variability of DSDs has its origin within a storm or between storms within a day. Physical processes leading to the formation of DSDs are then classified according to the vertical structure of radar data as measured by a UHF profiler collocated with the disdrometer. The DSD variability among different physical processes is larger than the day-to-day variability. A bias of 41% in rain accumulations is due to the DSD variability between physical processes. Accurate rain-rate estimation (∼7%) can be achieved only after the proper underlying physical process is identified and the associated R–Z relationship is used.