bluuebunny/crossref_metadata_2025 huggingface dataset:
A three-compartment thermometry model for the improved estimation of changes in body heat content
Authors: Jay Ollie , Gariépy Louise M. , Reardon Francis D. , Webb Paul , Ducharme Michel B. , Ramsay Tim , Kenny Glen P.
Published: August 2006

The aim of this study was to use whole body calorimetry to directly measure the change in body heat content (ΔHb) during steady-state exercise and compare these values with those estimated using thermometry. The thermometry models tested were the traditional two-compartment model of “core” and “shell” temperatures, and a three-compartment model of “core,” “muscle,” and “shell” temperatures; with individual compartments within each model weighted for their relative influence upon ΔHb by coefficients subject to a nonnegative and a sum-to-one constraint. Fifty-two participants performed 90 min of moderate-intensity exercise (40% of V̇o2 peak) on a cycle ergometer in the Snellen air calorimeter, at regulated air temperatures of 24°C or 30°C and a relative humidity of either 30% or 60%. The “core” compartment was represented by temperatures measured in the esophagus (Tes), rectum (Tre), and aural canal (Tau), while the “muscle” compartment was represented by regional muscle temperature measured in the vastus lateralis (Tvl), triceps brachii (Ttb), and upper trapezius (Tut). The “shell” compartment was represented by the weighted mean of 12 skin temperatures (T̄sk). The whole body calorimetry data were used to derive optimally fitting two- and three-compartment thermometry models. The traditional two-compartment model was found to be statistically biased, systematically underestimating ΔHb by 15.5% (SD 31.3) at 24°C and by 35.5% (SD 21.9) at 30°C. The three-compartment model showed no such bias, yielding a more precise estimate of ΔHb as evidenced by a mean estimation error of 1.1% (SD 29.5) at 24°C and 5.4% (SD 30.0) at 30°C with an adjusted R2 of 0.48 and 0.51, respectively. It is concluded that a major source of error in the estimation of ΔHb using the traditional two-compartment thermometry model is the lack of an expression independently representing the heat storage in muscle during exercise.
17β-Estradiol supplementation reduces tubulointerstitial fibrosis by increasing MMP activity in the diabetic kidney
Authors: Mankhey Richard W. , Wells Corinne C. , Bhatti Faizah , Maric Christine
Published: August 2006

We previously reported that supplementation with 17β-estradiol (E2) attenuates albuminuria, glomerulosclerosis, and tubulointerstitial fibrosis in diabetic nephropathy. The present study examined the mechanisms by which E2 regulates extracellular matrix (ECM) metabolism, a process that contributes to the development of glomerulosclerosis and tubulointerstitial fibrosis. The study was performed in female nondiabetic (ND), streptozotocin-induced diabetic (D), and diabetic with E2 supplementation (D+E2) Sprague-Dawley rats for 12 wk. Diabetes was associated with an increase in the renal expression of collagen α type IV [ND, 0.22 ± 0.02; D, 0.99 ± 0.09 relative optical density (ROD); P < 0.05] and fibronectin protein (ND, 0.36 ± 0.08; D, 1.47 ± 0.08 ROD; P < 0.05), as measured by Western blot analysis. E2 supplementation partially attenuated this increase in collagen α type IV (D+E2, 0.47 ± 0.10 ROD) and fibronectin (D+E2, 0.71 ± 0.16 ROD) protein expression associated with D. Diabetes was also associated with a decrease in the expression of matrix metalloproteinase (MMP) isoform MMP-2 (ND, 0.79 ± 0.01; D, 0.62 ± 0.06 ROD; P < 0.05) and MMP-9 protein (ND, 0.49 ± 0.02; D, 0.33 ± 0.03 ROD; P < 0.05). E2 supplementation restored MMP-2 and MMP-9 protein to levels similar or even greater than in the ND kidneys (MMP-2, 0.75 ± 0.06; MMP-9, 0.73 ± 0.01 ROD). The activities of MMP-2 (ND, 7.88 ± 0.44; D, 5.60 ± 0.54 ROD; P < 0.05) and MMP-9 (ND, 29.9 ± 1.8; D, 12.9 ± 2.3 ROD; P < 0.05), as measured by zymography, were also decreased with D. E2 supplementation restored MMP-2 and MMP-9 activity to levels similar to that in ND kidneys (MMP-2, 7.66 ± 0.35; MMP-9, 21.4 ± 2.9 ROD). We conclude that E2 supplementation is renoprotective by attenuating glomerulosclerosis and tubulointerstitial fibrosis by reducing ECM synthesis and increasing ECM degradation.
Obestatin acts in brain to inhibit thirst
Authors: Samson Willis K. , White Meghan M. , Price Christopher , Ferguson Alastair V.
Published: August 2006

Derived from the same prohormone, obestatin has been reported to exert effects on food intake that oppose those of ghrelin. The obestatin receptor GPR39 is present in brain and pituitary gland. Since the gene encoding those two peptides is expressed also in those tissues, we examined further the possible actions of obestatin in vivo and in vitro. Intracerebroventricular administration of obestatin inhibited water drinking in ad libitum-fed and -watered rats, and in food-and water-deprived animals. The effects on water drinking preceded and were more pronounced than any effect on food intake, and did not appear to be the result of altered locomotor/behavioral activity. In addition, obestatin inhibited ANG II-induced water drinking in animals provided free access to water and food. Current-clamp recordings from cultured, subfornical organ neurons revealed significant effects of the peptide on membrane potential, suggesting this as a potential site of action. In pituitary cell cultures, log molar concentrations of obestatin ranging from 1.0 pM to 100 nM failed to alter basal growth hormone (GH) secretion. In addition, 100 nM obestatin failed to interfere with the stimulation of GH secretion by GH-releasing hormone or ghrelin and did not alter the inhibition by somatostatin in vitro. We conclude that obestatin does not act in pituitary gland to regulate GH secretion but may act in brain to alter thirst mechanisms. Importantly, in rats the effects of obestatin on food intake may be secondary to an action of the peptide to inhibit water drinking.
Diaphragmatic nitric oxide synthase is not induced during mechanical ventilation
Authors: Van Gammeren Darin , Falk Darin J. , Deering Melissa A. , DeRuisseau Keith C. , Powers Scott K.
Published: August 2006

Mechanical ventilation (MV) is associated with diaphragmatic oxidative stress that contributes to both diaphragmatic atrophy and contractile dysfunction. However, the pathways responsible for oxidant production in the diaphragm during MV remain unknown. To address this issue, we tested the hypothesis that diaphragmatic nitric oxide synthase (NOS) activity is elevated during MV, resulting in nitration of diaphragmatic proteins. Rats were mechanically ventilated for 18 h, and time-matched, anesthetized but spontaneously breathing animals served as controls. Protein levels of endothelial NOS, inducible NOS, and neuronal NOS were measured in diaphragms from all animals. 3-Nitrotyrosine levels were also measured as an index of protein nitration, and S-nitrosothiol levels were measured as a marker of nitric oxide reactions with molecules containing sulfhydryl groups. Levels of nitrates and nitrites were measured as markers of stable end products of nitric oxide metabolism. Finally, as a marker of oxidative stress, diaphragmatic levels of reduced GSH were also analyzed. MV did not promote an increase in diaphragmatic protein levels of endothelial NOS or neuronal NOS. Moreover, inducible NOS was not detected in the diaphragms of either experimental group. Consistent with these findings, MV did not elevate diaphragmatic 3-nitrotyrosine levels in any subcellular fraction of the diaphragm, including the cytosolic, mitochondrial, membrane, and insoluble protein fractions. Moreover, prolonged MV did not elevate diaphragmatic levels of S-nitrosothiols, nitrate, or nitrite. Finally, prolonged MV significantly reduced diaphragmatic levels of GSH, which is consistent with diaphragmatic oxidative stress. Collectively, these data reveal that MV-induced oxidative stress in the diaphragm is not due to increases in nitric oxide production by NOS.
Cardiac mitochondrial damage and loss of ROS defense after burn injury: the beneficial effects of antioxidant therapy
Authors: Zang Qun , Maass David L. , White Jean , Horton Jureta W.
Published: August 2006

Mechanisms of burn-related cardiac dysfunction may involve defects in mitochondria. This study determined 1) whether burn injury alters myocardial mitochondrial integrity and function; and 2) whether an antioxidant vitamin therapy prevented changes in cardiac mitochondrial function after burn. Sprague-Dawley rats were given a 3° burn over 40% total body surface area and fluid resuscitated. Antioxidant vitamins or vehicle were given to sham and burn rats. Mitochondrial and cytosolic fractions were prepared from heart tissues at several times postburn. In mitochondria, lipid peroxidation was measured to assess oxidative stress, mitochondrial outer membrane damage and cytochrome- c translocation were determined to estimate mitochondrial integrity, and activities of SOD and glutathione peroxidase were examined to evaluate mitochondrial antioxidant defense. Cardiac function was measured by Langendorff model in sham and burn rats given either vitamins or vehicle. Twenty-four hours postburn, mitochondrial outer membrane damage was progressively increased to ∼50%, and cytosolic cytochrome- c gradually accumulated to approximately three times more than that measured in shams, indicating impaired mitochondrial integrity. Maximal decrease of mitochondrial SOD activity occurred 8 h postburn (∼63.5% of shams), whereas maximal decrease in glutathione peroxidase activity persisted 2–24 h postburn (∼60% of shams). In burn animals, lipid peroxidation in cardiac mitochondria increased 30–50%, suggesting burn-induced oxidative stress. Antioxidant vitamin therapy prevented burn-related loss of membrane integrity and antioxidant defense in myocardial mitochondria and prevented cardiac dysfunction. These data suggest that burn-mediated mitochondrial dysfunction and loss of reactive oxygen species defense may play a role in postburn cardiac dysfunction.
Dual PPARα/γ Agonist Tesaglitazar Reduces Atherosclerosis in Insulin-Resistant and Hypercholesterolemic ApoE*3Leiden Mice
Authors: Zadelaar A. Susanne M. , Boesten Lianne S.M. , Jukema J. Wouter , van Vlijmen Bart J.M. , Kooistra Teake , Emeis Jef J. , Lundholm Erik , Camejo German , Havekes Louis M.
Published: August 2006

Objective—

We investigated whether the dual PPARα/γ agonist tesaglitazar has anti-atherogenic effects in ApoE*3Leiden mice with reduced insulin sensitivity.

Methods and Results—

ApoE*3Leiden transgenic mice were fed a high-fat (HF) insulin-resistance–inducing diet. One group received a high-cholesterol (HC) supplement (1% wt/wt; HC group). A second group received the same HC supplement along with tesaglitazar (T) 0.5 μmol/kg diet (T group). A third (control) group received a low-cholesterol (LC) supplement (0.1% wt/wt; LC group). Tesaglitazar decreased plasma cholesterol by 20% compared with the HC group; cholesterol levels were similar in the T and LC groups. Compared with the HC group, tesaglitazar caused a 92% reduction in atherosclerosis, whereas a 56% reduction was seen in the cholesterol-matched LC group. Furthermore, tesaglitazar treatment significantly reduced lesion number beyond that expected from cholesterol lowering and induced a shift to less severe lesions. Concomitantly, tesaglitazar reduced macrophage-rich and collagen areas. In addition, tesaglitazar reduced inflammatory markers, including plasma SAA levels, the number of adhering monocytes, and nuclear factor κB-activity in the vessel wall.

Conclusions—

Tesaglitazar has anti-atherosclerotic effects in the mouse model that go beyond plasma cholesterol lowering, possibly caused by a combination of altered lipoprotein profiles and anti-inflammatory vascular effects.
U.S. Policy toward South Asia and Tibet during the Early Cold War
Authors: McMahon Robert J.
Published: August 2006

Events in South Asia in the 1950s and early 1960s had a long-term impact on the Cold War and on relations among the countries involved—China, India, Pakistan, the United States, and the Soviet Union. This article provides an overview of U.S. relations with South Asian countries during the early Cold War. It highlights the connections between U.S. policy priorities and commitments in South Asia on the one hand and developments in Tibet on the other. The article considers how U.S. policy priorities and actions in South Asia shaped, and were shaped by, China's reassertion of control over Tibet in the early 1950s and by the frictions that emerged between India and China in 1959 as a result of Beijing's brutal crackdown in Tibet.
The United States, Tibet, and the Cold War
Authors: Goldstein Melvyn C.
Published: August 2006

This article examines U.S. policy toward Tibet from the end of the 1940s to the end of the 1980s, especially the 1950s and 1960s. U.S. policy during this period operated on two levels. At the strategic level, the United States consistently supported China's claim of sovereignty over Tibet. But at the tactical level, U.S. policy varied a great deal over time, ranging from the provision of military and financial aid to Tibetan guerrilla forces in the 1950s and 1960s to the almost complete lack of official attention to Tibet in the 1970s and early 1980s. The article explains why the U.S. government has never accepted Tibet's claim to independence and why the question of Tibet, after falling into obscurity in the 1970s, reemerged on the U.S. agenda in the mid- to late 1980s. The article highlights the cynicism that has often characterized tactical shifts in U.S. policy.
The Tibetan Rebellion of 1959 and China's Changing Relations with India and the Soviet Union
Authors: Jian Chen
Published: August 2006

Tibet, which had enjoyed de facto independence from 1911 to 1950, was resubordinated to China in late 1950 and 1951 through a combination of political pressure and military force. On 10 March 1959 a mass revolt broke out in Lhasa, the capital of Tibet. Amid growing turmoil, the 14th Dalai Lama fled the capital. After Chinese troops moved into Lhasa on 20 March to crush the rebellion, the Tibetan leader took refuge in neighboring India. The Chinese People's Liberation Army quelled the unrest and disbanded the local government. This article looks back at those events in order to determine how the rebellion was perceived in China and what effect it had on relations with India.
Beyond Confrontation
Authors: Royo Sebastián
Published: August 2006

The proponents of globalization contend that European countries are now converging on an Anglo-American model of capitalism. Contrary to this prediction, this article shows that in Spain, globalization and the European Monetary Union have promoted rather than undermined cooperation among economic actors. Unable to escape from economic interdependence, they have developed coordinating capacities at the macro and micro levels to address and resolve tensions between economic interdependence and political sovereignty. In particular, this article analyzes the resurgence of national-level social bargaining in Spain in the 1990s. This development was partly the result of the reorientation of the strategies of trade unions. They have supported social bargaining as a defensive strategy to retake the initiative and influence policy outcomes. This article shows that successful social bargaining depends on not only the organization of the social actors, the main claim of the neocorporatist literature, but also the interests and strategies of the actors themselves.
Viral gene expression during the establishment of human cytomegalovirus latent infection in myeloid progenitor cells
Authors: Cheung Allen K. L. , Abendroth Allison , Cunningham Anthony L. , Slobedman Barry
Published: August 2006

Human cytomegalovirus (HCMV) establishes and maintains a latent infection in myeloid cells and can reactivate to cause serious disease in allograft recipients. To better understand the molecular events associated with the establishment of latency, we tracked the virus following infection of primary human myeloid progenitor cells at days 1, 2, 3, 5, and 11. At all time points, the viral genome was maintained in most cells at approximately 10 copies. Infectious virus was not detected, but virus could be reactivated by extended fibroblast coculture. In contrast to wild-type HCMV, the viral genome was rapidly lost from myeloid progenitors infected with ultraviolet (UV)–inactivated virus, suggesting viral gene expression was required for efficient establishment of latency. To identify viral genes associated with the establishment phase, RNA from each time point was interrogated using custom-made HCMV gene microarrays. Using this approach, we detected expression of viral RNAs at all time points. The pattern of expression differed from that which occurs during productive infection, and decreased over time. This study provides evidence that a molecular pathway into latency is associated with expression of a unique subset of viral transcripts. Viral genes expressed during the establishment phase may serve as targets for therapies to interrupt this process.
Wogonin sensitizes resistant malignant cells to TNFα- and TRAIL-induced apoptosis
Authors: Fas Stefanie C. , Baumann Sven , Zhu Jia Yun , Giaisi Marco , Treiber Monika K. , Mahlknecht Ulrich , Krammer Peter H. , Li-Weber Min
Published: August 2006

TNFα has previously been used in anticancer therapy. However, the therapeutic application of TNFα was largely limited due to its general toxicity and the fact that it activates the NF-κB–family transcription factors, which are proinflammatory and antiapoptotic. To overcome this problem in vitro, specific NF-κB inhibitors or transcription or protein synthesis inhibitors such as actinomycin D and cycloheximide are usually used in combination to increase TNFα killing of tumor cells. However, these agents also cause harmful side effects in vivo. We show here that wogonin, derived from the popular Chinese herb Huang-Qin, attenuates NF-κB activity by shifting TNFα-induced free radical ·O2– to a more reduced nonradical product, H2O2, and thereby sensitizes TNFα-resistant leukemia cells to TNFα-induced apoptosis. Importantly, wogonin does not affect the viability of normal peripheral blood T cells. Wogonin also sensitizes TRAIL-induced apoptosis. Our data suggest a potential use of wogonin as a TNFα or TRAIL adjuvant for cancer treatment. Our data also demonstrate how a herbal compound enhances killing of tumor cells with reduced side effects compared with other treatments.
Targeting the activation-induced antigen CD137 can selectively deplete alloreactive T cells from antileukemic and antitumor donor T-cell lines
Authors: Wehler Thomas C. , Nonn Marion , Brandt Britta , Britten Cedrik M. , Gröne Mark , Todorova Mariya , Link Irina , Khan Shamsul A. , Meyer Ralf G. , Huber Christoph , Hartwig Udo F. , Herr Wolfgang
Published: August 2006

In HLA-incompatible hematopoietic stem cell transplantation, alloreactive donor T cells recognizing recipient mismatch HLA cause severe graft-versus-host disease (GVHD). Strategies allowing the selective depletion of alloreactive T cells as well as the enhancement of graft-versus-malignancy immunity would be beneficial. We generated donor CD8 T-cell lines in vitro using allogeneic recipient cells mismatched at a single HLA class I allele or haplotype as stimulators. Recipient cells were obtained from acute myeloid leukemias, renal-cell carcinomas, and CD40L-induced B lymphoblasts. Resulting alloreactive T cells were activated by incubating day 21 T-cell cultures with HLA-mismatch transfected K562 cells or recipient-derived fibroblasts. Selective allodepletion (SAD) was subsequently performed by a newly developed immunomagnetic depletion approach targeting the tumor necrosis factor receptor molecule CD137 (4-1BB). Compared with other activation-induced antigens, CD137 showed a superior performance based on a consistently low baseline expression and a rapid up-regulation following alloantigen stimulation. In 15 different SAD experiments, the frequency of alloreactive CD8 T cells was reduced to a median of 9.5% compared with undepleted control populations. The allodepleted T-cell subsets maintained significant antitumor and antiviral CD8 responses. In vitro expansion of tumor-reactive T cells followed by CD137-mediated SAD might enhance the antitumor efficacy of T-cell allografts with lower risk of inducing GVHD.
Sustained alterations in biodistribution of stem/progenitor cells in Tie2Cre+α4f/f mice are hematopoietic cell autonomous
Authors: Priestley Gregory V. , Ulyanova Tatiana , Papayannopoulou Thalia
Published: August 2006

We have generated Tie2Cre+α4f/f mice with documented α4-integrin ablation in hematopoietic and endothelial cells. A prominent feature in this model is a sustained, significant increase in circulating progenitors at levels higher than the levels seen with Tie2Cre+VCAM-1f/f mice. To test whether phenotypic differences are due to contributions by ligands other than VCAM-1 in bone marrow, or to α4-deficient endothelial cells or pericytes, we carried out transplantation experiments using these mice as donors or as recipients. Changes in progenitor biodistribution after transplantation were seen only with α4-deficient donor cells, suggesting that these cells were necessary and sufficient to reproduce the phenotype with no discernible contribution by α4-deficient nonhematopoietic cells. Because several similarities are seen after transplantation between our results and those with CXCR4−/− donor cells, the data suggest that VLA4/VCAM-1 and CXCR4/CXCL12 pathways contribute to a nonredundant, ongoing signaling required for bone marrow retention of progenitor cells during homeostasis.
The risk of dialysis access thrombosis is related to the transforming growth factor–β1 production haplotype and is modified by polymorphisms in the plasminogen activator inhibitor–type 1 gene
Authors: Lazo-Langner Alejandro , Knoll Greg A. , Wells Philip S. , Carson Nancy , Rodger Marc A.
Published: August 2006

Transforming growth factor–β1 (TGF-β1) and plasminogen activator inhibitor–type 1 (PAI-1) might play a role in the development of fibrosis and stenosis of hemodialysis vascular accesses. We studied polymorphisms in the TGFβ1 (869T>C; 915G>C), and PAI-1 (4G/5G) genes in 416 hemodialysis patients (107 access thrombosis cases, 309 controls), to determine if they are related to vascular access thrombosis. Three TGF-β1 production haplotypes (low, intermediate, and high) were defined according to the combination of polymorphisms found. The adjusted odds ratio (OR) and 95% confidence interval (CI) for access thrombosis in low TGF-β1 producers was 7.31 (2.15-24.88; P = .001). The interaction between low TGF-β1 production haplotype and the 4G/4G PAI-1 genotype was strongly associated with access thrombosis (adjusted OR 19.3; 95% CI 2.82-132.40; P = .003). Mean access thrombosis–free survival times in years (95% CI) were 14.65 (12.05-17.25), 11.96 (8.67-15.25), and 4.94 (3.06-6.83) in high, intermediate, and low TGF-β1 producers, respectively (P = .044). Analysis of the synergy index and the case-only cross-product supported the presence of an interaction. We concluded that low TGF-β1 production haplotype is a risk factor for hemodialysis access thrombosis and that in the presence of the 4G/4G PAI-1 genotype there is an additional increase in risk.
Glucocorticoids Act Directly on Osteoclasts to Increase Their Life Span and Reduce Bone Density
Authors: Jia D. , O’Brien C. A. , Stewart S. A. , Manolagas S. C. , Weinstein R. S.
Published: August 2006

Glucocorticoid administration to mice results in a rapid loss of bone mineral density due to an imbalance in osteoblast and osteoclast numbers. Whereas excess glucocorticoids reduce both osteoblast and osteoclast precursors, cancellous osteoclast number surprisingly does not decrease as does osteoblast number, presumably due to the ability of glucocorticoids to promote osteoclast life span. Whether glucocorticoids act directly on osteoclasts in vivo to promote their life span and whether this contributes to the rapid loss of bone with glucocorticoid excess remains unknown. To determine the direct effects of glucocorticoids on osteoclasts in vivo, we expressed 11β-hydroxysteroid dehydrogenase type 2, an enzyme that inactivates glucocorticoids, specifically in the osteoclasts of transgenic mice using the tartrate-resistant acid phosphatase promoter. Bone mass, geometry, and histomorphometry were similar in untreated wild-type and transgenic animals. Glucocorticoid administration for 7 d caused equivalent increases in cancellous osteoblast apoptosis, and equivalent decreases in osteoblasts, osteoid, and bone formation, in wild-type and transgenic mice. In contrast, glucocorticoids stimulated expression of the mRNA for calcitonin receptor, an osteoclast product, in wild-type but not transgenic mice. Consistent with the previous finding that glucocorticoids decrease osteoclast precursors and prolong osteoclast life span, glucocorticoids decreased cancellous osteoclast number in the transgenic mice but not wild-type mice. In accord with this decrease in osteoclast number, the loss of bone density observed in wild-type mice was strikingly prevented in transgenic mice. These results demonstrate for the first time that the early, rapid loss of bone caused by glucocorticoid excess results from direct actions on osteoclasts.
Insulin-Like Peptide 6: Characterization of Secretory Status and Posttranslational Modifications
Authors: Lu Chunxia , Walker William H. , Sun Jinhong , Weisz Ora A. , Gibbs Robert B. , Witchel Selma F. , Sperling Mark A. , Menon Ram K.
Published: August 2006

Insulin-like peptide 6 (Insl6) is a member of the insulin/relaxin superfamily with unknown biological function(s). In the current report, we establish that meiotic and postmeiotic germ cells of the testis are the principal sites of expression of Insl6. Analysis of stably or transiently transfected cells revealed that Insl6 is a secreted protein localized to the endoplasmic reticulum and Golgi. Secretion could be detected in both CHO and GC2 germ cells and was sensitive to brefeldin A treatment. In cell lysates, the predominant Insl6 band was approximately 28 kDa in size. In contrast, the predominant Insl6 species in the supernatant was 8 kDa in size, suggesting posttranslational processing of the precursor protein. Ectopically expressed Insl6 is processed and secreted in furin-deficient LoVo cells and in CHO cells treated with a furin inhibitor, although the size profile of the secreted protein is altered suggesting that Insl6 is a substrate for furin action. Furthermore, mutation of a putative furin cleavage site in the Insl6 peptide resulted in aberrant processing of the Insl6 peptide. Additional investigations of the structure of Insl6 protein provided evidence for posttranslational modifications of Insl6, including the presence of disulfide bonds, glycosylation, and ubiquitination. On the basis of the demonstrated secretory status of Insl6, we speculate that the physical proximity of the germ cell to the Sertoli cell renders the Sertoli cell a likely candidate for Insl6 action.
Nakagami and the Denial of Lineage: On Maternity, Abjection, and the Japanese Outcast Class
Authors: Long Margherita
Published: August 2006

margherita long is Assistant Professor in the Department of Comparative Literature and Foreign Languages at the University of California, Riverside. Her published conversation on Nakagami with participants at the Shingû Seminar appeared in Waseda Bungaku 29.5 (November 2004): 22-53. She is currently completing a manuscript called This Perversion Called Love: Tanizaki, Freud, and Feminist Theory.
Hex acts with β-catenin to regulate anteroposterior patterning via a Groucho-related co-repressor and Nodal
Authors: Zamparini Andrea L. , Watts Tim , Gardner Clare E. , Tomlinson Simon R. , Johnston Geoffrey I. , Brickman Joshua M.
Published: August 2006

In Xenopus, the establishment of the anteroposterior axis involves two key signalling pathways, canonical Wnt and Nodal-related TGFβ. There are also a number of transcription factors that feedback upon these pathways. The homeodomain protein Hex, an early marker of anterior positional information, acts as a transcriptional repressor, suppressing induction and propagation of the Spemman organiser while specifying anterior identity. We show that Hex promotes anterior identity by amplifying the activity of canonical Wnt signalling. Hex exerts this activity by inhibiting the expression of Tle4, a member of the Groucho family of transcriptional co-repressors that we identified as a Hex target in embryonic stem (ES) cells and Xenopus embryos. This Hex-mediated enhancement of Wnt signalling results in the upregulation of the Nieuwkoop centre genes Siamois and Xnr3, and the subsequent increased expression of the anterior endodermal marker Cerberus and other mesendodermal genes downstream of Wnt signalling. We also identified Nodal as a Hex target in ES cells. We demonstrate that in Xenopus, the Nodal-related genes Xnr1 and Xnr2, but not Xnr5 and Xnr6, are regulated directly by Hex. The identification of Nodal-related genes as Hex targets explains the ability of Hex to suppress induction and propagation of the organiser. Together, these results support a model in which Hex acts early in development to reinforce a Wnt-mediated, Nieuwkoop-like signal to induce anterior endoderm, and later in this tissue to block further propagation of Nodal-related signals. The ability of Hex to regulate the same targets in both Xenopus and mouse implies this model is conserved.
The disparate nature of “intergenic” polyadenylation sites
Authors: Lopez Fabrice , Granjeaud Samuel , Ara Takeshi , Ghattas Badih , Gautheret Daniel
Published: August 2006

The termination of mature eukaryotic mRNAs occurs at specific polyadenylation sites located downstream from stop codons in the 3′-untranslated region (UTR). An accurate delineation of these sites is essential for the study of 3′-UTR-based gene regulation and for the design of pertinent probes for transcriptome analysis. Although typical poly(A) sites are located between 0 and 2 kb from the stop codon, EST sequence analyses have identified sites located at unexpectedly long ranges (5–10 kb) in a number of genes. Here we perform a complete mapping of EST and full-length cDNA sequences on the mouse and human genome to observe putative poly(A) sites extending beyond annotated 3′-ends and into the intergenic regions. We introduce several quality parameters for poly(A) site prediction and train a classification tree to associate P-values to predicted sites. We observe a higher than background level of high-scoring sites up to 12–15 kb past the stop codon, both in human and mouse. This leads to an estimate of about 5000 human genes having unreported 3′-end extensions and about 3500 novel polyadenylated transcripts lying in present “intergenic” regions. These high-scoring, long-range poly(A) sites corresponding to novel transcripts and gene extensions should be incorporated into current human and mouse gene repositories.
Chlorite and Illite Compositions from Upper Silurian Rock Salts, Retsof, New York
Authors: Bodine M. W. , Standaert R. R.
Published: August 2006

Chlorite and illite are the major clay minerals in silicate assemblages from a rock salt bed in the Vernon Formation (Upper Silurian) at Retsof, New York. Textural features and Br content of the salt indicate precipitation from shallow marine brine with no subsequent postdepositional recrystallization. Sample mounting procedure for electron microprobe analysis involves clay particle dispersion, sedimentation, and transferral to a planar silver print surface. The 001 face of the flake, rather than the conventional polished plane, constitutes the analyzed surface. Microprobe analysis of the chlorite (80 grains from four samples) yields a mean aggregate Mg-rich clinochlore composition of
$$(M{g_{4.51}}Fe_{0.23}^ + A{l_{1.21}})(A{l_{1.09}}S{i_{2.91}}){O_{10}}{(OH)_{8,}}$$
which is relatively uniform among grains and among samples. Its unique composition when compared with normal shale chlorites suggests an authigenic origin in the marine evaporite environment. Illite (106 grains from five samples) has a mean aggregate composition of
$${{\rm{K}}_{0.85}}(A{l_{1.61}}Fe_{0.20}^{3 + }M{g_{0.23}})(A{l_{0.76}}S{i_{3.24}}){O_{10}}{(OH)_2}$$
with little variation among samples. The illite is distinctly less degraded than normal shale illite suggesting some recrystallization occurred in the hypersaline environment. Extensive compositional variation among illite flakes within each sample may reflect alteration of several different detrital micaceous minerals. The term hyperhalmyrolysis is introduced to denote mineral reactions which occur in the marine hypersaline environment.

Diagenesis effected improved crystallinity and undoubtedly involved isochemical recrystallization of the bulk silicate assemblage. Metasomatism of the assemblage during diagenesis, however, appears to be negligible.
Mössbauer Spectra of Dioctahedral Smectites
Authors: Rozenson I. , Heller-Kallai L.
Published: August 2006

Mössbauer spectra of 15 smectites were investigated. In these samples, ferric iron occupies both M(1) and M(2) octahedral sites, the distribution being partly determined by the relative covalency of the bonds formed.

The quadrupole splittings are linearly related to b−3. They show that Fe3+ octahedra are much more distorted in montmorillonite and beidellite than in nontronite and volkonskoite and that M(1) sites are more prone to change than M(2). Ferrous iron occurs in relatively undistorted octahedra in some otherwise distorted octahedral sheets and vice versa.
Hectorite Complexes with Cu(II) and Fe(II)-1,10-Phenanthroline Chelates
Authors: Berkheiser V. E. , Mortland M. M.
Published: August 2006

Characteristics and properties of complexes of a smectite (hectorite) with 1,10-phenanthroline (phen) chelates with iron or copper were determined by a variety of physical and chemical measurements. The complex ions showed high selectivity for the hectorite surface. Basal spacings of 17.4 Å were produced by Fe(II) or Cu(II) analogues of M(phen)32+ hectorite. Adsorption of gases and vapors by the M(phen)32+ hectorite complex revealed large surface areas and reflected intrinsic characteristics of the complex ions. Lower surface areas were found for copper phen hectorite than iron phen hectorite probably because of the loss of a ligand from the Cu(II) ion. ESR spectra confirmed that appreciable Cu(II) existed as the bis-phen complex under certain conditions. An increase in the oxidation potential of the Fe(phen)32+-Fe(phen)33+ couple above that in pure solvent was noted when these complexes were supported by the mineral surface.
Dissolution of Two Australian Palygorskites in Dilute Acid
Authors: Singer Arieh
Published: August 2006

The dissolution of two relatively pure Australian palygorskites in mild acid was studied. For both palygorskites, Si and Mg releases were linear with respect to added acid. The rate of Si release with acid addition is equal to 0.66 μmol Si for each μmol H+ added in both palygorskites. The corresponding releases of Mg were 1.2 μmol for the Al-poor and 0.47 μmol for the Al-rich minerals. Mg appears to be preferentially released into solution over Si, and both Mg and Fe appear to be preferentially released into solution over Al, suggesting a lower stability of Mg and Fe-rich palygorskites compared to Al-rich varieties. The free energy of formation of one of the palygorskites was estimated as equal to −1143.7 kcal/mol.
Mineralogy of Al-Hasa Desert Soils (Saudi Arabia)
Authors: Aba-Husayn Mansur M. , Sayegh Antoine H.
Published: August 2006

X-ray mineralogical examination of the 2–20 μm fraction of oriented samples from a highly calcereous swamp soil and neighbouring Mio-Pliocene strata in Al-Hasa showed a wide range in mineralogy: attapulgite, illite, montmorillonite, chlorite and kaolinite, in decreasing order. Powder X-ray diffraction revealed an abundance of attapulgite, calcite, quartz and in a few samples, traces of dolomite, Fe-oxides, feldspars and gypsum.

The soils are believed to have been formed by deposition of highly calcareous wind-borne silt particles in an already formed swamp. The surface and subsurface horizons are underlain by an organic residue layer, 30–50 cm thick, containing 14–36% organic matter. The whole profile sits on hard, impervious, sedimentary layers that mineralogically resemble some strata of the outcrop.

Attapulgite and illite are the most abundant and common clay minerals in the soils and strata, but are most pronounced in the latter. Attapulgite not only occurs in Al-Hasa, but is widely distributed in the Arabian Peninsula; from east of the Mediterranean through the deserts of Syria and Iraq down to eastern Saudi Arabia, where it occurs only in association with limestone parent material. In this area of extreme aridity (Al-Hasa), the origin of the minerals and their relative abundance is believed to be associated with the source of sediment since minimum alteration seems to have taken place after deposition.
Internal Surface Area of Wyoming Bentonite from Swelling Relationships
Authors: Fink D. H.
Published: August 2006

The internal surface area of Na-Wyoming bentonite was determined for linearly swelling pastes, using a physically based equation which describes such swelling. Information required is simply the linear relationship between interplatelet spacing, determined by X-ray powder diffraction, vs total water content determined gravimetrically. However, before the three-unknown parameter equation can be so applied, that portion of external-pore water, which normally increases linearly commensurately as interstitial water increases, must be decreased to zero. This was accomplished by adding dilute quantities of NaCl salt to the clay-paste system to decrease the attractive forces between positive-edge and negative-face sites, and stirring vigorously to further destroy the card-house structure and align the clay platelets.
A Microprobe Analysis of Type X Molecular Sieve
Authors: Weeks T. J. , Passoja D. E.
Published: August 2006

Microprobe analysis of a synthetic large crystal type X zeolite shows that the silica to alumina molar ratio increases from the crystal center to the exterior.
The Hydrothermal Transformation Of Sodium And Potassium Smectite Into Mixed-Layer Clay
Authors: Eberl Dennis , Hower John
Published: August 2006

The transformation of sodium and potassium smectite into mixed-layer clay was followed in hydrothermal kinetic experiments. Glasses of beidellite composition and the Wyoming bentonite were used as starting materials. Temperatures ranged between 260 and 490°C at 2 kbar pressure, and run times ranged between 6 hr and 266 days.

The course of the reactions was found to be strongly affected by interlayer chemistry. When potassium was the interlayer cation, increasing reaction produced the series: randomly interstratified illite/smectite-ordered interstratified illite/smectite-illite. This sequence is equivalent to that formed in shales during burial diagenesis. With interlayer sodium and temperatures above 300°C, an aluminous beidellite (Black Jack analog)-rectorite-paragonite series was realized. The difference between these two diagenetic families is discussed. Below 300°C, sodium beidellite formed randomly interstratified mixed-layer clay much like potassium beidellite, except that a higher layer charge was required to produce sodium mica-like layers. The higher charge resulted from sodium's higher hydration energy. The difference in hydration energy between potassium and sodium may account for the fixation of potassium rather than sodium in illite during burial diagenesis.

The appearance of ordered interlayering in mixed-layer phases is also related to interlayer chemistry. Ordering formed in sodium clays at high expandabilities, whereas it never appeared in the potassium clays above approximately 35% expandable. The appearance of ordering may be partly related to the polarizing power of the mica-like layers.

Phase diagrams, constructed from the kinetic experiments and from the composition and occurrence of natural clays, are presented for the systems paragonite and muscovite-2 quartz-kaolinite-excess water. This study also reports the first synthesis of a Kalkberg-type mixed-layer clay.
A Natural Clay Organic Complex from Andalusian Black Earth
Authors: Perez Rodriguez J. L. , Weiss Armin , Lagaly Gerhard
Published: August 2006

Protein complexes of smectites in soils are difficult to detect if the usual smectite tests show no peculiarities. Andalusian black earths are typical examples. Investigation of the alkylam-monium derivatives, however, allows detection of adhered macromolecules which might be protein-like although this cannot be proved exactly.

Investigation of artificial clay-protein complexes reveals different types of clay protein interactions. Calcium smectites adsorb proteins mainly on the external surfaces, the macromolecules being anchored in the interlayer spaces. Sodium smectites give partial crystalline products in which the silicate layers are distributed in the protein matrix.

Exchange of alkylammonium ions can be used as a tool for detection of the protein. If this is adsorbed on external surfaces (calcium smectites) the increased layer separation during the cation exchange enables the macromolecules to slip between the layers and the basal spacing of the alkylammonium derivatives are changed in characteristic ways. The partial crystalline sodium clay-protein complexes are reorganized by alkylammonium ions to regular structures. The proteins are not displaced completely from the silicate surfaces so that the basal spacing of the alkylammonium derivatives are enhanced in comparison with pure montmorillonite.
The Determination of Adsorbed Na, K, Mg and Ca on Sediments Containing CaCO3 and MgCO3
Authors: Neal Colin
Published: August 2006

A method for the determination of the cations of Na, K, Mg and Ca adsorbed on clay minerals mixed with CaCO3 and MgCO3 is described. An ethanolic solution of LiCl-CsCl is used to displace the exchangeable cations. Blank determinations performed using either a second ethanolic leach or a second LiCl-CsCl leach, are used to correct for carbonate dissolution. Details of the methods development are given.

The method has been tested using mixtures of homoionic forms (Na, K, Mg, Ca) of smectite and kaolinite with either CaCO3 or MgCO3. The smectite and kaolinite were found to have total CECs (with standard deviations) of 765 (4.4) and 39.8 (0.52) mequiv kg−1, respectively. The amount of cation exchanged was found to vary directly with the proportion of clay mineral in the mixture; regression coefficients consistently greater than 0.997 were obtained.

Other tests with smectite-CaCO3 mixtures in sea-waters of various salinity vindicated the use of the method with heteroionic forms of smectite. These tests also suggest that the phenomenon of fixation observed in most other studies of clay minerals in estuarine conditions might be redundant. It is contended that there is an urgent need for this suggestion to be tested.
A Proposed Phase Diagram for Illite, Expanding Chlorite, Corrensite and Illite-Montmorillonite Mixed Layered Minerals
Authors: Velde Bruce
Published: August 2006

New and published experimental data on hydrothermally treated (2-kbar water pressure, 300–400°C natural clay minerals is used to construct phase diagrams in composition and pressure-temperature space which define the phase relations of mixed layering solid solution in dioctahedral (illite-montmorillonite) and trioctahedral expanding chlorite and corrensite-like minerals. Three major relations are established:

(1)

The R3+, i.e. Al13+ and/or Fe3+, content of the assemblage will control whether or not an expanding chlorite or corrensite phase will appear. These minerals are R3+-rich in composition as well as R2+ (Mg and Fe2+)-rich.

(2)

Temperature-pressure variables control the type and composition of the mixed layered illite-montmorillonite mineral which is stable with aluminous phases. A sequence of different types of mixed layered ordering can be established which might be correlated with diagenetic or epimetamorphic grade.

(3)

The presence of ‘metamorphic’ trioctahedral phyllosilicate phases, i.e. those due to the effects of earliest metamorphism, is correlated with the P-T-X variables. These phases include 7 Å chlorite (iron-rich), 14 Å chlorite and the expanding chlorite and corrensite-like minerals.

It is not possible to give absolute temperatures for the different reactions implied by the phase diagram due to the slow rate of crystallization in the experiments. However, the general sequence of assemblages and the phase relations proposed should correspond to those which are encountered in nature when pressure and temperature vary.
Experimental Transformation of 2M Sericite into a Rectorite-Type Mixed-Layer Mineral by Treatment with Various Salts
Authors: Tomita Katsutoshi
Published: August 2006

Some dehydroxylated sericites were boiled with solutions of various salts. A rectorite-like regular mixed-layer was formed when 2M sericite was treated with solution containing salts such as NaNO3, Na2SO4, CaSO4, CaCl2, MgCl2 and MgSO4 respectively. A random mica/montmorillonite mixed-layer was formed from 1M sericite. In order to change the 2M sericite into a regularly interstratified mineral, they are heated to the temperature range of dehydroxylation. The formation of a regularly interstratified mineral from 2M sericite can be explained by the change in the (OH) bond direction after the extraction of the potassium ion.
Porphyrin Adsorption by Clay Minerals
Authors: Kosiur David R.
Published: August 2006

A study was undertaken to investigate the adsorption of hemin, protoporphyrin and hematoporphyrin by kaolinite and a Ca-montmorillonite in aqueous solutions buffered at pH 4 and 9.

Although experimental restrictions at pH 4 prevented the complete characterization of the adsorption isotherms, kaolinite did exhibit a saturation of exchange sites by the cationic porphyrins. Both kaolinite and montmorillonite displayed a similar saturation of sites by the porphyrins in their anionic forms at pH 9. The major differences in the adsorption isotherms are attributed to differences in the exchange capacities of the clays.

Adsorption of the porphyrins at pH 9 was inhibited largely by phosphate treatment of the clays; this effect is interpreted as blockage of the anion exchange sites by irreversibly-bound phosphate.
The Co-Ordination of Hydrated Cu(II)- and Ni(II)-Ions on Montmorillonite Surface
Authors: Velghe Firmin , Schoonheydt Robert A. , Uytterhoeven Jan B.
Published: August 2006

The optical spectra of Cu2+ and Ni2+ on Camp Berteau montmorillonite after lyophilization and evacuation at room temperature are characteristic for the presence of Cu(H2O)42+ and Ni(H2O)62+ in the interlamellar space. The most probable ligand field parameters for Cu(H2O)2+4 are Dqxy = 1310 cm−1, Ds = 1807 cm−1 and Dt = 664cm−1. The covalent character of the Cu2+-OH2 bond is not negligible as indicated by the orbital reduction factors k∣∣2 = 0.66 and k⊥2 = 0.76. This is also the case for Ni(H2O)62+ which is characterized by a ligand field strength, Dq = 850 cm−1 and an electronic repulsion parameter B = 920 cm−1. After desorption in vacuum the optical spectra of Cu2+ were poorly resolved, while Ni2+ was present partially as (Ol)3Ni2+, partially as (Ol)3Ni-OH2 where Ol means an oxygen of the hexagonal rings in the tetrahedral layers.