bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparison of Lipoprotein(a) Levels between Elderly and Middle‐Aged Men with Coronary Artery Disease
Authors: CICEK HULYA , BAYIL SIBEL , ZER YASEMIN , CELIK AHMET , GEYIKLI ICLAL
Published: April 2007

Abstract:  Lipoprotein(a) [Lp(a)] is known to be a risk factor for atherosclerotic disease in middle‐aged men, but the role of Lp(a) in women and in the elderly is less clear. In most studies, excess Lp(a) is not associated with increased risk for persons >65 years of age. This study examined the strength of association of a number of risk factors to coronary artery disease (CAD) in groups of men <65 years (n= 108) and >65 of age (n= 66) with angiographically documented significant narrowing of coronary arteries. Serum Lp(a) concentrations were determined; elevated Lp(a) is positively associated with CAD for men <65 years (adjusted OR: 2.45, P <0.05) but not for men >65 of age (adjusted OR: 0.56, P= NS). For middle‐aged men, elevated Lp(a) appears to be an independent risk factor for premature CAD, and the importance of Lp(a) as a risk factor appears to decrease with age. These data suggest that the utility of Lp(a) lipoprotein levels in predicting the risk of CAD in older men is limited. Factors, such as age; sex; levels of total cholesterol, low‐density lipoprotein (LDL) cholesterol, and triglycerides; carotid‐wall thickness; smoking status; the presence or absence of diabetes and systolic and diastolic hypertension; body mass index (BMI); and other traditional risk factors, must be evaluated together to determine the risk of CAD for the entire population.
Pseudoexfoliation Syndrome and Trace Elements
Authors: YILDIRIM ZUHAL , UÇGUN N. IREM , KILIÇ NEDRET , GÜRSEL E. , SEPICI‐DINÇEL AYLIN
Published: April 2007

Abstract:  To investigate the role of zinc and copper in the development of pseudoexfoliation (PSX) syndrome, 34 cataract patients with PSX syndrome and 27 cataract patients without PSX syndrome were included in the study and groups were matched for age and gender. During the cataract surgery, lenses were obtained intraoperatively, frozen under liquid nitrogen, and kept at −70°C until processing. Zinc and copper concentrations were measured by atomic absorption spectrophotometric method after the homogenization (acid hydrolysis) of dried lenses. The mean concentration of zinc in the lens from patients with PSX (20.33 ± 8.76 μg/g tissue; range 11.04–42.94 μg/g tissue) was significantly lower than that measured in the lens of patients without PSX (28.88 ± 15.32 μg/g tissue; range 12.02–64.32 μg/g tissue) (P < 0.05). The mean concentration of copper in the lens from patients with PSX (29.51 ± 10.05 μg/g tissue; range 12.69–59.71 μg/g tissue) and in the lens of patients without PSX (39.72 ± 25.64 μg/g tissue; range 12.38–92.14 μg/g tissue) was not statistically different. The decreased content of zinc could increase oxidative stress. The results support the role of oxidative stress in the development of PSX in cataract patients.
The Importance of Serum Lipids in Exudative Diabetic Macular Edema in Type 2 Diabetic Patients
Authors: UÇGUN NIL IREM , YILDIRIM ZUHAL , KILIÇ NEDRET , GÜRSEL EMIN
Published: April 2007

Abstract:  To evaluate the relationship between serum lipid levels and exudative diabetic maculopathy in patients with nonproliferative diabetic retinopathy, 27 patients with exudative diabetic macular edema were included in group A and 27 patients without exudative diabetic macular edema were included in group B. All 54 patients have nonproliferative diabetic retinopathy. Blood cholesterol, triglyceride, high‐density lipoprotein (HDL) cholesterol, low‐density lipoprotein (LDL) cholesterol, very low‐density lipoprotein (VLDL) cholesterol, hemoglobin A1c (HbA1c), and hemoglobin levels were measured in patients in group A and group B. The mean concentration of cholesterol in group A (224.30 ± 49.49 mg/dL), in group B (197.78 ± 41.49 mg/dL); triglyceride in group A (199.11 ± 90.51 mg/dL), in group B (160.78 ± 65.30 mg/dL); HDL in group A (43.48 ± 10.62 mmol/L), in group B (42.37 ± 10.92 mmol/L); LDL in group A (150.59 ± 43.96 mg/dL), in group B (124.37 ± 40.28 mg/dL); VLDL in group A (40.52 ± 16.54 mg/dL), in group B (37.89 ± 23.70 mg/dL); HbA1c in group A (9.62 ± 2.50), in group B (7.36 ± 1.62 g/dL); and hemoglobin in group A (13.46 ± 1.6 g/dL), in group B (13.90 ± 1.77 g/dL). Serum cholesterol (P= 0.38), LDL (P= 0.026), and HbA1c (P= 0.000) levels were different between the two groups. Triglyceride, HDL, VLDL, and hemoglobin levels were not different between the two groups. We must consider regulation of high blood sugar and elevated total serum cholesterol or LDL levels in patients with macular edema and high hard exudates.
Age‐Related Paraoxonase Activity Changes in Turkish Population
Authors: SARUHAN ERCAN , OLGUN ABDULLAH , ÖZTÜRK KAMILE , AKMAN SERIF , ERBIL M. KEMAL
Published: April 2007

Abstract:  Paraoxonase1 (PON1) is a high‐density lipoprotein (HDL)‐associated enzyme capable of hydrolyzing diverse substrates from organophosphate (OP) toxins to oxidized phospholipids. As such, it has been linked with both the prevention of OP poisoning and inhibition of atherosclerosis initiated by oxidatively modified low‐density lipoprotein (LDL). The aim of this study was to investigate, with aging, the activity of PON1 associated with HDL and partially responsible for its antiatherogenic activity. The study involved 187 individuals (67 males and 120 females) divided into three groups according to their ages, young (n= 49; 20–44 years, mean age = 30.12 ± 6.6 years), middle aged (n= 25; 45–64 years, mean age = 52 ± 5.6 years), and elderly subjects (n= 113; 65–95 years, mean age = 78.94 ± 6.2 years). Interestingly, serum total cholesterol and LDL‐cholesterol levels significantly decreased with age (P < 0.05). The elderly aged group had also significantly lower body mass index than the middle aged group (P < 0.05). Serum paraoxonase activity and HDL cholesterol levels remained unchanged with age. The prevalence of phenotype AA, AB, and BB in our subjects' group was 40.6%, 45.9%, and 13.5%, respectively.
Mitochondrial DNA Alterations in Aging
Authors: ÖZTÜRK KAMILE , OLGUN ABDULLAH , SARUHAN ERCAN , ERGEN AYDAN , AKMAN SERIF , ERBIL M. KEMAL
Published: April 2007

Abstract:  During the aging process, the increase of mitochondrial DNA (mtDNA) alterations has been reported. In this study, we investigated deletions/insertions in the ∼ 2.4‐kb region (from 14680 to 578 bp) of mtDNA covering D‐loop region. A total of 96 individuals (ages between 20 and 94 years) were screened in this study. Genomic DNA was purified from whole blood samples. The 2.4‐kb region of mtDNA was amplified with PCR and visualized by agarose gel electrophoresis. The sequence of the amplicon was confirmed in one sample by sequencing. We detected mtDNA deletions in only two cases (ages 26 and 30 years) at this resolution. As a result, there is no increase in the major deletions/insertions in the analyzed mtDNA region with aging. Complete sequencing of this region is needed to detect any age‐dependent changes.
Involvement of Mortalin in Cellular Senescence from the Perspective of its Mitochondrial Import, Chaperone, and Oxidative Stress Management Functions
Authors: YAGUCHI TOMOKO , AIDA SATOSHI , KAUL SUNIL C. , WADHWA RENU
Published: April 2007

Abstract:  Mortalin (mtHSP70/GRP75) is a heat uninducible member of hsp70 family of proteins. Some of the established features of mortalin include its various subcellular sites, multiple binding partners, and differential subcellular distribution in normal and immortal cells. Overexpression of mortalin leads to extended life span in nematode and normal human cells. On the other hand, it serves as a major target for oxidation and was shown to be involved in old age pathologies including Parkinson's and Alzheimer's disease. Since mortalin interacts with many proteins, its modifications in response to stress and damage caused by intracellular oxidation are likely to generate pleiotropic effects. For example, (a) inefficient import of mitochondrial proteins by mortalin–Tim complexes may result into inefficient mitochondrial genesis, energy generation, and functional decline and (b) inefficient chaperoning of proteins can result into a garbage catastrophe.
Knocking Down p53 with siRNA Does Not Affect the Overexpression of p21WAF‐1 after Exposure of IMR‐90 hTERT Fibroblasts to a Sublethal Concentration of H2O2 Leading to Premature Senescence
Authors: ZDANOV STEPHANIE , DEBACQ‐CHAINIAUX FLORENCE , TOUSSAINT OLIVIER
Published: April 2007

Abstract:  Premature senescence of IMR‐90 human diploid fibroblasts (HDFs) expressing telomerase was induced by exposure to sublethal concentration of H2O2, with appearance of several biomarkers of cellular senescence like enlarged cell shape, senescence‐associated β‐galactosidase (SA ß‐gal) activity, and cell cycle arrest. The induction of stress‐induced premature senescence (SIPS) was associated with a transient increase in DNA‐binding activity of p53 and an increased expression of p21WAF‐1. p53 small interferent RNA (siRNA) affected the basal level of p21WAF‐1 mRNA but did not affect the overexpression of p21WAF‐1 after stress. This siRNA approach confirms previous results obtained with other methods.
Age‐Dependent Effects on Functional Aspects in Human Satellite Cells
Authors: BECCAFICO S. , PUGLIELLI C. , PIETRANGELO T. , BELLOMO R. , FANÒ G. , FULLE S.
Published: April 2007

Abstract:  In humans aging is a complex process that determines many physical and metabolic alterations correlated to the accumulation of oxidative damage in different tissues. Sarcopenia is an age‐related nonpathological condition that includes a progressive loss of mass and strength in skeletal muscle, associated with a decline in the fibers' functional capability. This condition could be correlated to abnormal reactive oxygen species (ROS) accumulation with consequent fiber oxidative damage. This complex situation is not only evident in mature muscle fibers but also in muscle resident satellite cells (involved in fiber damage repairing) in which some functional parameters, at least for that concerns the Ca2+ homeostasis, seem to be modified. In fact, our data show that there is an age‐dependent increase of lipid peroxidation, in cultured myotubes (differentiated and fused satellite cells) after 7 days of in vitro differentiation. In these substrates also the capacity of these cells to produce Ca2+ transient in response to various stimuli (ATP, caffeine, nicotine, KCl) is, sometimes, drastically modified. In particular, the presence of an age‐dependent defective status of excitation–contraction (EC) coupling apparatus is supported by a single cell Ca2+ analysis obtained from myotubes (derived from aged muscles) in the presence of 40 mM caffeine or 40 mM KCl. The alkaloid presence induces a complete emptying of ryanodine‐dependent calcium stores indicating a probable integrity both of SR‐terminal cisternae and/or the specific Ca2+ channel known as RyR1. However, if a sarcolemmal depolarization is induced by the addition of 40 mM KCl in the experimental medium then Ca2+ release RyR1‐dependent can be observed only if Ca2+ is present in the experimental solution. These results suggest that the EC uncoupling status could be due to the alteration of the interaction between RyR and DHPR. The two receptors are present and functionally active in myotubes from aged donors but they are probably still not in the right localization. These results suggest that during donor's life the satellite cells undergo an aging process similar to the one observed in skeletal muscle tissue, even if they are in a quiescence status for most of the time.
Markers of Oxidative Stress in Erythrocytes during Aging in Humans
Authors: RIZVI SYED IBRAHIM , MAURYA PAWAN KUMAR
Published: April 2007

Abstract:  The correlation between antioxidant capacity and oxidative damage during aging has been reported in several tissues in different species; however, data on changes of oxidative stress markers in plasma and erythrocytes of healthy populations during aging are few and sometimes contradictory. Since antioxidant capacity of the plasma is related to dietary intake of antioxidants, it is important to study the correlation between antioxidant capacity of the plasma and markers of oxidative stress in different populations. In the present study we report the age‐dependent alteration in erythrocyte malondialdehyde (MDA), intracellular‐reduced glutathione (GSH), and membrane sulphydryl (SH) groups in the Indian population and also correlate these parameters with total plasma antioxidant potential. We show an age‐dependent increase in erythrocyte MDA level and a decrease in GSH and membrane −SH group concentration. The alterations in these parameters correlated significantly with total antioxidant capacity of the plasma. We observe a higher oxidative stress in the Indian population compared to values reported for European subjects emphasizing the need to establish age‐dependent reference values for oxidative stress markers in different populations and in studies involving their role in different disease conditions.
Deuteronation and Aging
Authors: OLGUN ABDULLAH , ÖZTÜRK KAMILE , BAYIR SELDA , AKMAN SERIF , ERBIL M. KEMAL
Published: April 2007

Abstract:  Deuterium has one proton and one neutron in its atomic nucleus, but hydrogen has only proton. The natural abundance of deuterium is 1 per ∼6600 hydrogen atoms. Therefore deuterated water (both HOD + D2O [heavy water]) abundance is 1 per ∼3300 water molecules. One dissociation product of deuterated and heavy water is deuteron (proton + neutron, D+, H2OD+/D3O+). Because heavy water has a lower ionization constant than water, the D+/H+ ratio is ∼1/15,000 in biological fluids. O‐D bond length is shorter than O‐H, and D‐O‐D angle is lesser than H‐O‐H. Once a deuteron exchanges with proton on the water‐exposed surface of a macromolecule, it can lead to a conformational change and the reverse exchange will be less likely. Deuteron bonds are stronger than proton bonds. Therefore an increase of deuteronated macromolecules can be expected in due course of time. In order to test this hypothesis, we conducted a pilot study and measured the D/H ratio in the tails of three Sprague–Dawley rats at different ages (4 weeks, 5 weeks, and >1‐year old) by elemental analysis coupled with isotope ratio mass spectrometry (EA‐IRMS) technique. To prevent the effect of daily water consumption, the homogenized tails were lyophilized before analysis. The results, as mean of several measurements, of 4 weeks, 5 weeks, and >1‐year‐old rats were ‰–94 ± 9.56, ‰–101.71 ± 6.89, ‰–83.68 ± 3.46 δ(2H) relative to VSMOW, respectively. Although there is a slight increase in >1‐year‐old rat, the difference among the animals was not significant. We propose that, before reaching to a final conclusion about the accumulation of deuterium with aging, the measurements should be done not in whole tissue samples but in purified macromolecules from a larger set of animals.
Hemodialysis and Protein Oxidation Products
Authors: COŞKUN CİHAN , KURAL ALEV , DÖVENTAŞ YASEMİN , KOLDAŞ MACİT , ÖZTURK HÜMEYRA , İNAL BERRİN BERÇİK , GÜMÜŞ ALPER
Published: April 2007

Abstract:  The presence of a chronic inflammatory state has also been widely documented in end‐stage renal disease patients receiving maintenance hemodialysis (HD). It is commonly attributed to the constantly renewed activation of circulating neutrophils and monocytes following blood passage through dialysis circuits and subsequent generation of activated complement components due to contact of plasma with bioincompatible membranes and/or transfer of endotoxins from the dialyzate to the blood compartment. This conjunction leads to a massive generation of reactive oxygen species (ROS), for example, superoxide anion, hydrogen peroxide, hydroxyl radical, and chlorinated oxidants, such as hypochlorous acid by activated neutrophils. The exquisite vulnerability of proteins to ROS is now well documented. Oxidation of amino acid residues, such as tyrosine, leads to the formation of dityrosine, protein aggregation, cross‐linking, and fragmentation. Dityrosine‐containing protein cross‐linking products in the plasma of dialysis patients are named as advanced oxidation protein products (AOPP). In addition, advanced glycation end‐products (AGE) is a protein carbonyl compound and produced by protein–ROS interaction. We investigated both the effect of the renewed activation of the immune cells, due to blood–dialyzer interaction over protein oxidation products like AOPP and AGE, among chronic renal failure (CRF) patients receiving maintenance HD, and choice of dialyzers like high flux or the other group on protein oxidation product levels.
The Natural Biogerontology Portfolio
Authors: GREY AUBREY D. N. J. DE
Published: April 2007

Abstract:  The early days of biogerontology were blessed with an undiluted forthrightness concerning the field's ultimate goals, epitomized by its leaders. Luminaries from Pearl to Comfort to Strehler declared the desirability of eliminating aging with no more diffidence than that with which today's oncologists aver that they seek a cure for cancer. The field's subsequent retreat from this position garnered a modicum of political acceptability and public financial support, but all biogerontologists agree that this fell, and continues to fall, vastly short of the funding that the prospect of even a modest postponement of aging would logically justify. The past 20 years' discoveries of life‐extending genetic manipulations in model organisms have weakened the argument that a policy of appeasement of the public's ambivalence about defeating aging is our only option; some of the biogerontologists responsible for these advances have espoused views of which our intellectual forefathers would be proud, without noticeably harming their own careers. With the recent emergence of a detailed, ambitious, but practical roadmap for the comprehensive defeat of aging, this process has moved further: our natural and most persuasive public stance is, more than ever, to reembrace the same unassailable logic that served pioneering biogerontologists perfectly well. In particular, we are in a position to explain that the disparate strands of contemporary biomedical gerontology are not in conflict, but rather that they constitute a portfolio of approaches with a range of potential efficacies and degrees of difficulty of implementation, which can save more lives together than any can save individually, and all of which thus merit intensive pursuit.
The Role of Cellular Senescence in Werner Syndrome
Authors: DAVIS TERENCE , WYLLIE FIONA S. , ROKICKI MICHAL J. , BAGLEY MARK C. , KIPLING DAVID
Published: April 2007

Abstract:  Werner syndrome (WS) is a premature aging disorder used as a model of normal human aging. WS individuals have several characteristics of normal aging, such as cataracts, hair graying, and skin aging, but manifest these at an early age. Additionally, WS individuals have high levels of inflammatory diseases, such as atherosclerosis and type 2 diabetes. The in vivo aging in WS is associated with accelerated aging of fibroblasts in culture. The cause of the accelerated senescence is not understood, but may be due to the genomic instability that is a hallmark of WS. Genome instability results in activation of stress kinases, such as p38, and the p38‐specific inhibitor SB203580, prevents the accelerated senescence seen in WS fibroblasts. However, oxidative damage plays a role, as low oxygen conditions and antioxidant treatment revert some of the accelerated senescence phenotype. The effects of oxidative stress appear to be suppressible by SB203580; however, it does not appear to be transduced by p38. As SB203580 is known to inhibit other kinases in addition to p38, this suggests that more than one kinase pathway is involved. The recent development of p38 inhibitors with different binding properties, specificities, and oral bioavailability, and of new potent and selective inhibitors of JNK and MK2, will make it possible to dissect the roles of various kinase pathways in the accelerated senescence of WS cells. If this accelerated senescence is reflective of WS aging in vivo, these kinase inhibitors may well form the basis of antiaging therapies for individuals with WS.
Improvement of Immune Cell Functions in Aged Mice Treated for Five Weeks with Soybean Isoflavones
Authors: BAEZA ISABEL , DE CASTRO NURIA M. , ALVARADO CARMEN , ÁLVAREZ PEDRO , ARRANZ LORENA , BAYÓN JULIÁN , DE LA FUENTE MÓNICA
Published: April 2007

Abstract:  Aging is associated with an impaired immune system as well as with a decline of several hormones, such as estrogens. Dietary phytoestrogens have been proposed as an alternative to hormone replacement therapy. The beneficial action of soybean compounds is probably due to isoflavones, whose role as immunomodulators has been investigated with increasing interest. The aim of the present work was to study whether a 5‐week administration of a diet enriched in soybean isoflavones and green tea could influence the immune function of mice that were sham‐operated or ovariectomized. Natural killer activity (NK) and lymphoproliferation in response to the mitogens concanavaline A (Con A) and lipopolysaccharide (LPS), were studied in peritoneal leukocytes. Both treatments with soybean or green tea plus soybean were highly effective in improving these immune parameters with respect to control groups. Since the immune system is a marker of health and a predictor of longevity, an adequate treatment with isoflavones could be useful in slowing down the effects of the aging process through an improvement in the two relevant immune functions studied.
The Effect of Intrahippocampal Beta Amyloid (1‐42) Peptide Injection on Oxidant and Antioxidant Status in Rat Brain
Authors: CETIN FERIHAN , DINCER SIBEL
Published: April 2007

Abstract:  In some animal models, cognitive impairment and neurodegenerative disorders that mimic Alzheimer's disease (AD) can be reproduced by intracerebral or intracerebroventricular administration of peptide (Aβ) beta amyloid. Evidence suggests that oxidative stresses are involved in the mechanism of Aβ‐induced neurotoxicity and AD pathogenesis. Exposure to Aβ increases lipid peroxidation, protein oxidation, and the formation of hydrogen peroxide in cultured cells. Nitric oxide (NO) has significant physiological roles in the central nervous system and also it can be implicated in neurodegenerative diseases because of its free radical properties. The purpose of this study is to search the effects of intrahippocampal Aβ (1‐42) injection on malondialdehyde (MDA), glutathione (GSH), and nitrite plus nitrate (NOx) levels in temporal cortex and basal forebrain in rats. In this study, male adult Wistar albino rats were divided into two groups. Aβ (1‐42) peptide (10 μg/2 μL) was administered bilaterally as a single injection into the hippocampal fissure by a Hamilton microsyringe. Distilled water was administered to the control group by using the same procedure. Ten days after the Aβ (1‐42) injection, the rats were decapitated and brains were rapidly removed. MDA, GSH, and NOx levels were analyzed spectrophotometrically in temporal cortex and basal forebrain. MDA levels and NOx were increased 10 days after the injection of Aβ (1‐42) in temporal cortex and basal forebrain, but no statistical significance was found compared to control group. However, GSH levels were significantly higher in temporal cortex and basal forebrain in the Aβ (1‐42)‐injected group than the control group (P < 0.05). In conclusion, increased levels of GSH in temporal cortex and basal forebrain after the intrahippocampal Aβ (1‐42) injection show that a protective mechanism might develop due to oxidative stress.
Effects of Taurine in Cellular Responses to Oxidative Stress in Young and Middle‐Aged Rat Liver
Authors: YILDIRIM ZUHAL , KILIÇ NEDRET , OZER ÇIGDEM , BABUL AYDAN , TAKE GULNUR , ERDOGAN DENIZ
Published: April 2007

Abstract:  Aging is related with an increased cellular level of lipid peroxides and reactive oxygen species (ROS). The useful effects of taurine as an antioxidant in biological systems have been attributed to its capability to stabilize biomembranes, to scavenge ROS, and to decrease the peroxidation of unsaturated membrane lipids. The aim of the present study was to investigate the effects of taurine on malondialdehyde (MDA), glutathione (GSH), glutathione peroxidase (GPx), thioredoxin reductase (TR), and endothelial nitric oxide synthase (eNOS) in young and middle‐aged rat liver. There was not a significant difference in liver MDA levels between the control groups of young and middle‐aged rats (P > 0.05). However, liver GSH levels, and GPx and TR activities between the control groups of young and middle‐aged rats were significantly different (P < 0.05). Liver MDA level was significantly lower in the taurine group of middle‐aged rats (P < 0.05). Liver GSH levels, and GPx and TR activities were significantly increased in the taurine group of middle‐aged rats when compared to the control group (P < 0.05). Liver MDA level was significantly lower in the taurine group of young rats than the ones in the control group (P < 0.05). Liver TR activity was significantly increased in the taurine group of young rats when compared to the control group (P < 0.05). Liver GPx activity was not statistically different between the taurine and the control groups in young rats (P > 0.05). Liver GSH levels were not different between the young taurine and the control groups (P > 0.05). Immunohistochemical studies exhibited no change in eNOS activity after taurine injection in young rats. However, in middle‐aged rats, taurine lowered the eNOS reactivity to the same level found in young rats. These results suggested that exogenous taurine might play a role in aging by means of its reducing effects on free radical levels in parallel to an increase in the antioxidant capacity.
A Familial Thyrotropin (TSH) Receptor Mutation Provides in Vivo Evidence that the Inositol Phosphates/Ca2+ Cascade Mediates TSH Action on Thyroid Hormone Synthesis
Authors: Grasberger Helmut , Van Sande Jacqueline , Hag-Dahood Mahameed Ahmad , Tenenbaum-Rakover Yardena , Refetoff Samuel
Published: April 2007

Context: In the human thyroid gland, TSH activates both the cAMP and inositol phosphates (IP) signaling cascades via binding to the TSH receptor (TSHR). Biallelic TSHR loss-of-function mutations cause resistance to TSH, clinically characterized by hyperthyrotropinemia, and normal or reduced thyroid gland volume, thyroid hormone output, and iodine uptake.

Objective: We report and study a novel familial TSHR mutation (L653V).

Results: Homozygous individuals expressing L653V had euthyroid hyperthyrotropinemia. Paradoxically, patients had significantly higher 2-h radioiodide uptake and 2- to 24-h radioiodide uptake ratios compared with heterozygous, unaffected family members, suggesting an imbalance between iodide trapping and organification. In transfected COS-7 cells, the mutant TSHR had normal surface expression, basal activity, and TSH-binding affinity, equally (2.2-fold) increased EC50 values for TSH-induced cAMP and IP accumulation, and normal maximum cAMP generation. In contrast, the efficacy of TSH for generating IP was more than 7-fold lower with the mutant compared with wild-type TSHR.

Conclusions: We identified and characterized a TSHR defect, preferentially affecting the IP pathway, with a phenotype distinct from previously reported loss-of-function mutations. Results provide the first in vivo evidence for the physiological role of the TSHR/IP/Ca2+ cascade in regulating iodination. According to systematic in vitro mutagenesis studies, other TSHR mutations can result in even complete loss of IP signaling with retained cAMP induction. We hypothesize that such TSHR mutations could be the cause in unexplained partial organification defects.
Receptor Interacting Protein 140 Regulates Expression of Uncoupling Protein 1 in Adipocytes through Specific Peroxisome Proliferator Activated Receptor Isoforms and Estrogen-Related Receptor α
Authors: Debevec Darja , Christian Mark , Morganstein Daniel , Seth Asha , Herzog Birger , Parker Malcolm , White Roger
Published: April 2007

Expression of uncoupling protein 1 (Ucp1) mRNA is elevated in differentiated adipocytes derived from brown or white adipose tissue devoid of the nuclear receptor corepressor receptor interacting protein 140 (RIP140). Increased expression is mediated in part by the recruitment of peroxisome proliferator activated receptors α and γ, together with estrogen-related receptor α, which functions through a novel binding site on the Ucp1 enhancer. This demonstrates that regulation of Ucp1 expression in the absence of RIP140 involves derepression of at least three different nuclear receptors. The ability to increase expression of Ucp1 by β-adrenergic signaling is independent of RIP140, as shown by the action of the β3-adrenergic agonist CL 316,243 to stimulate expression in both brown and white adipocytes in the presence and absence of the corepressor. Therefore, the expression of this metabolic uncoupling protein in adipose cells is regulated by inhibition as well as activation of distinct signaling pathways.
Force activates smooth muscle α-actin promoter activity through the Rho signaling pathway
Authors: Zhao Xiao-Han , Laschinger Carol , Arora Pam , Szászi Katalin , Kapus Andras , McCulloch Christopher A.
Published: April 2007

In pressure or volume overload, hypertrophic growth of the myocardium is associated with myofibroblast differentiation, a process in which cardiac fibroblasts express smooth muscle α-actin (SMA). The signaling mechanisms that mediate force-induced myofibroblast differentiation and SMA expression are not defined. We examined the role of the Rho–Rho-kinase pathway in force-induced SMA expression in fibroblasts using an in vitro model system that applies static tensile forces (0.65 pN/μm2) to integrins via collagen-coated magnetite beads. Force maximally induced RhoA activation at 10 minutes that was localized to force application sites and required intact actin filaments. Force application induced phosphorylation of LIM kinase (5-10 minutes) and an early dephosphorylation of cofilin (5 minutes) that was followed by prolonged cofilin phosphorylation. These responses were blocked by Y27632, an inhibitor of Rho kinase. Force promoted actin filament assembly at force application sites (10-20 minutes), a process that required Rho kinase and cofilin. Force application induced nuclear translocation of the transcriptional co-activator MRTF-A but not MRTF-B. Nuclear translocation of MRTF-A required Rho kinase and intact actin filaments. Force caused 3.5-fold increases of SMA promoter activity that were completely blocked by transfection of cells with dominant-negative MRTF-A or by inhibition of Rho kinase or by actin filament disassembly. These data indicate that mechanical forces mediate actin assembly through the Rho–Rho-kinase–LIMK cofilin pathway. Force-mediated actin filament assembly promotes nuclear translocation of MRTF and subsequent activation of the SMA promoter to enhance SMA expression.
Post-translational integration of tail-anchored proteins is facilitated by defined molecular chaperones
Authors: Abell Benjamin M. , Rabu Catherine , Leznicki Pawel , Young Jason C. , High Stephen
Published: April 2007

Tail-anchored (TA) proteins provide an ideal model for studying post-translational integration at the endoplasmic reticulum (ER) of eukaryotes. There are multiple pathways for delivering TA proteins from the cytosol to the ER membrane yet, whereas an ATP-dependent route predominates, none of the cytosolic components involved had been identified. In this study we have directly addressed this issue and identify novel interactions between a model TA protein and the two cytosolic chaperones Hsp40 and Hsc70. To investigate their function, we have reconstituted the membrane integration of TA proteins using purified components. Remarkably, we find that a combination of Hsc70 and Hsp40 can completely substitute for the ATP-dependent factors present in cytosol. On the basis of this in vitro analysis, we conclude that this chaperone pair can efficiently facilitate the ATP-dependent integration of TA proteins.
Characterization ofSpo11-dependent and independent phospho-H2AX foci during meiotic prophase I in the male mouse
Authors: Chicheportiche Alexandra , Bernardino-Sgherri Jacqueline , de Massy Bernard , Dutrillaux Bernard
Published: April 2007

Meiotic DNA double strand breaks (DSBs) are indicated at leptotene by the phosphorylated form of histone H2AX (γ-H2AX). In contrast to previous studies, we identified on both zygotene and pachytene chromosomes two distinct types of γ-H2AX foci: multiple small (S) foci located along autosomal synaptonemal complexes (SCs) and larger signals on chromatin loops (L-foci). The S-foci number gradually declined throughout pachytene, in parallel with the repair of DSBs monitored by repair proteins suggesting that S-foci mark DSB repair events. We validated this interpretation by showing the absence of S-foci in Spo11–/– spermatocytes. By contrast, the L-foci number was very low through pachytene. Based on the analysis of γ-H2AX labeling after irradiation of spermatocytes, the formation of DSBs clearly induced L-foci formation. Upon DSB repair, these foci appear to be processed and lead to the above mentioned S-foci. The presence of L-foci in wild-type pachytene and diplotene could therefore reflect delayed or unregulated DSB repair events. Interestingly, their distribution was different in Spo11+/– spermatocytes compared with Spo11+/+ spermatocytes, where DSB repair might be differently regulated as a response to homeostatic control of crossing-over. The presence of these L-foci in Spo11–/– spermatocytes raises the interesting possibility of yet uncharacterized alterations in DNA or chromosome structure in Spo11–/– cells.
F-actin binding is essential for coronin 1B function in vivo
Authors: Cai Liang , Makhov Alexander M. , Bear James E.
Published: April 2007

Coronins are conserved F-actin binding proteins that have been implicated in a variety of processes including fibroblast migration, phagocytosis, and chemotaxis. Recent data from our lab indicate that coronin 1B coordinates Arp2/3-dependent actin filament nucleation and cofilin-mediated filament turnover at the leading edge of migrating fibroblasts. Analysis of coronin function has been hampered by the lack of a clear understanding of how coronin interacts with F-actin. Here, we identify a surface-exposed conserved arginine residue at position 30 (R30), which is crucial for coronin 1B binding to F-actin both in vitro and in vivo. Using actin co-sedimentation, we demonstrate that coronin 1B binds with high affinity to ATP/ADP-Pi–F-actin (170 nM) and with 47-fold lower affinity to ADP–F-actin (8 μM). In contrast to a previous study, we find no evidence for enhanced cofilin binding to F-actin in the presence of either coronin 1B or coronin 1A. Instead, we find that coronin 1B protects actin filaments from cofilin-induced depolymerization. Consistent with an important role for interactions between coronin 1B and F-actin in vivo, an R30D coronin mutant that does not bind F-actin localizes inefficiently to the leading edge. Furthermore, our analysis indicates that F-actin binding is absolutely required for coronin 1B to exert its effects on whole-cell motility and lamellipodial dynamics.
Src-dependent phosphorylation of β2-adaptin dissociates the β-arrestin–AP-2 complex
Authors: Fessart Delphine , Simaan May , Zimmerman Brandon , Comeau Jonathan , Hamdan Fadi F. , Wiseman Paul W. , Bouvier Michel , Laporte Stéphane A.
Published: April 2007

β-arrestins are known to act as endocytic adaptors by recruiting the clathrin adaptor protein 2 (AP-2) complex to G-protein-coupled receptors (GPCRs), linking them to clathrin-coated pits (CCPs) for internalization. They also act as signaling molecules connecting GPCRs to different downstream effectors. We have previously shown that stimulation of the angiotensin II (Ang II) type 1 receptor (AGTR1, hereafter referred to as AT1R), a member of the GPCR family, promotes the formation of a complex between β-arrestin, the kinase Src and AP-2. Here, we report that formation of such a complex is involved in the AT1R-mediated tyrosine phosphorylation of β2-adaptin, the subunit of AP-2 involved in binding β-arrestin. We identify a crucial tyrosine residue in the ear domain of β2-adaptin and show in vitro that the phosphorylation of this site regulates the interaction between β-arrestin and β2-adaptin. Using fluorescently tagged proteins combined with resonance energy transfer and image cross-correlation spectroscopy approaches, we show in live cells that β2-adaptin phosphorylation is an important regulatory process for the dissociation of β-arrestin–AP-2 complexes in CCPs. Finally, we show that β2-adaptin phosphorylation is involved in the early steps of receptor internalization. Our findings not only unveil β2-adaptin as a new Src target during AT1R internalization, but also support the role of receptor-mediated signaling in the control of clathrin-dependent endocytosis of receptors.
Cortical centralspindlin and Gα have parallel roles in furrow initiation in earlyC. elegansembryos
Authors: Verbrugghe Koen J. C. , White John G.
Published: April 2007

Evidence from various systems suggests that either asters or the midzone of the mitotic spindle are the predominant determinants of cleavage plane position. Disrupting spindle midzone formation in the one-cell Caenorhabditis elegans embryo, such as by using mutants of the centralspindlin component ZEN-4, prevents completion of cytokinesis but does not inhibit furrowing. However, furrowing is inhibited by the simultaneous depletion of ZEN-4 with either PAR-2 or Gα, which are required for asymmetric divisions. Through studies of other genes required for the presence of an intact spindle midzone containing microtubule bundles, we found that furrowing failed in the absence of PAR-2 or Gα only when centralspindlin was absent from the furrow. We also found spindle length or microtubule distribution did not correlate with furrow initiation. We propose that centralspindlin acts redundantly with Gα to regulate furrow initiation.
Integrated control of suspension and front steering to enhance vehicle handling
Authors: March C , Shim T
Published: April 2007

Integration of vehicle chassis control system has gained increasing attention since it can improve the vehicle safety and performance through effective coordination of individual control systems. This paper presents the development of an integrated control system of active front steering and normal force control using fuzzy reasoning to enhance the vehicle-handling performance. Individual control systems were first developed, and then their performances were compared with that of the integrated system. The simulation results indicate that the integrated chassis control scheme utilizing the steering and suspension controllers has proven to be more effective in attaining the desired performance that would not be attained individually.
Characterization and dynamic response of an exhaust gas recirculation venturi for internal combustion engines
Authors: Luján J M , Galindo J , Vera F , Climent H
Published: April 2007

This article describes different measurement techniques used on an exhaust gas recirculation (EGR) venturi. The main objective of this study is to assess the effect produced by the EGR venturi on the manifold flows of reciprocating internal combustion engines. An understanding of this behaviour is important for performing optimum designs for the connected pipes within the venturi. The presentation of an engine modelled and combined with facilities of steady and pulsating flow allows rigorous characterization of the behaviour of such a feature to be obtained, while taking into account the different operating conditions in which it can function.
An investigation into differential braking strategies on a banked road for vehicle stability control
Authors: Chung Taeyoung , Yi Kyongsu
Published: April 2007

This paper presents a differential braking strategy on a bank road for vehicle stability control (VSC). Road bank angles have a direct influence on vehicle dynamics and lateral acceleration measurement. A three-degree-of-freedom yaw plane vehicle model with road bank angle disturbances has been used in the design of a differential braking control law. To incorporate the road bank angle into the differential braking strategy for VSC, estimated bank angles have been used. A dynamic road bank angle estimator has been tuned and validated using a test vehicle. Real-time human-in-the-loop simulation studies on the differential braking strategy on a banked road have been conducted using a vehicle simulator. Simulation results in realistic driving situations have shown that a VSC system with the control law incorporating the road bank angles has an advantageous capability in achieving the desired behaviour of the vehicle.
Experimental validation of a finite element model of a composite tibia
Authors: Gray H A , Zavatsky A B , Taddei F , Cristofolini L , Gill H S
Published: April 2007

Composite bones are synthetic models made to simulate the mechanical behaviour of human bones. Finite element (FE) models of composite bone can be used to evaluate new and modified designs of joint prostheses and fixation devices. The aim of the current study was to create an FE model of a composite tibia and to validate it against results obtained from a comprehensive set of experiments.

For this, 17 strain rosettes were attached to a composite tibia (model 3101, Pacific Research Laboratories, Vashon, Washington, USA). Surface strains and displacements were measured under 13 loading conditions. Two FE models were created on the basis of computed tomography scans. The models differed from each other in the mesh and material properties assigned. The experiments were simulated on them and the results compared with experimental results. The more accurate model was selected on the basis of regression analysis.

In general, experimental strain measurements were highly repeatable and compared well with published results. The more accurate model, in which the inner elements representing the foam were assigned isotropic material properties and the elements representing the epoxy layer were assigned transversely isotropic material properties, was able to simulate the mechanical behaviour of the tibia with acceptable accuracy. The regression line for all axial loads combined had a slope of 0.999, an intercept of -6.24 microstrain, and an R2 value of 0.962. The root mean square error as a percentage was 5 per cent.
Concentric and eccentric shoulder rehabilitation biomechanics
Authors: Kohles S S , Gregorczyk K N , Phillips T C , Brody L T , Orwin J F , Vanderby R
Published: April 2007

The use of an impulse-momentum (IM) exercise technique was investigated for end-stage shoulder rehabilitation. The objectives of this study were to: (a) quantify the net shoulder joint forces and moments while using an IM system and (b) test the influence of gender and muscle loading type (concentric or eccentric) on kinetic and kinematic parameters. Fourteen healthy adults (eight males, six females) performed a repeated measures experiment on an instrumented device utilizing a cabled shuttle system. While maintaining 90° of shoulder abduction and 90° of elbow flexion, the subjects externally rotated their upper arm from 0° to 90° (concentric acceleration) and then internally rotated their upper arm back from 90° to the 0° position (eccentric deceleration). Shoulder joint forces and moments as well as rotational work and power were calculated using inverse dynamics (free-body forces and moments calculated at intersegmental joint centres). Overall concentric peak forces and moments were greater than eccentric peak forces and moments ( P < 0.0001). Joint forces and moments reached a maximum during the initial phase of concentric loading (0° to 45°) compared with any other rotational position in the loading cycle (concentric 45° to 90° or eccentric 90° to 0°). The results also indicate that males experienced higher ( P < 0.0001) average resultant peak joint forces (concentric 0° to 45°=108.0 N and eccentric 90° to 45°=87.2 N) than females (concentric 0° to 45°=74.7 N and eccentric 45° to 0°=56.0 N). In addition, males experienced higher ( P < 0.0001) average resultant peak joint moments (concentric 0° to 45°=30.4 N m and eccentric 45° to 0°=21.0 N m) than females (concentric 0° to 45°=19.7 N m and eccentric 45° to 0°=12.8 N m).
The influence of femoral condylar lift-off on the wear of artificial knee joints
Authors: Jennings L M , Bell C J , Ingham E , Komistek R D , Stone M H , Fisher J
Published: April 2007

In vivo fluoroscopic studies of patients with total knee replacements (TKRs) have shown lift-off of the femoral condyles from the tibial insert. This study investigated the influence of femoral condylar lift-off on the ultra-high molecular weight polyethylene (UHMWPE) wear of fixed bearing (FB) and rotating platform mobile bearing (RP MB) total knee replacements, using a physiological knee joint simulator. In the absence of lift-off, the RP MB knees exhibited a lower wear rate of 5.2;;2.2 mm3 per million cycles (mm3/MC) compared with 8.8;;4.8 mm3/MC for the FB knees. The presence of femoral condylar lift-off was found to accelerate the wear of the FB and RP MB knees tested in this study to 16.4;;2.9 and 16.9;;2.9 mm3/MC respectively. For the RP MB knees the increase in wear rate was more marked, resulting in a similar wear rate for both designs of knee under lift-off conditions. In both cases the medial condyle displayed more wear damage. This study has shown that a small amount of abduction/adduction lift-off and medial-lateral shift increases wear and that the increase in wear is design dependent. In this simulator test, lift-off was simulated on every cycle, whereas the amount of wear and effect of lift-off clinically would depend on the frequency of occurrence of lift-off in vivo.
Increase of load-carrying capacity under follower load generated by trunk muscles in lumbar spine
Authors: Kim Kyungsoo , Kim Yoon Hyuk , Lee SuKyoung
Published: April 2007

The load-carrying capacity of the spine has been experimentally shown to increase substantially when the resultant force of all loads applied on the spine is directed in accordance to its curvature, which is called a ‘follower load (FL)’. However, there have been few studies to investigate the muscle forces producing the FL owing to the difficulty of the relevant experimental measurements. This study investigated whether trunk muscle activations could be found for transmitting an external load within a range of FL direction. A two-dimensional finite element model of a lumbar spine and 117 pairs of trunk muscles was developed in the sagittal plane. An optimization technique was utilized to estimate the muscle forces generating the FL and the corresponding responses of the lumbar spine under two loading cases: the upright neutral standing posture and the posture holding 200 N in the hands. For each loading case, the muscle forces required to generate the FL could be found and the corresponding responses of the lumbar spine validated that the FL could increase the load-carrying capacity. The results showed that the FL could be produced in vivo by trunk muscles to increase the load-carrying capacity.