bluuebunny/crossref_metadata_2025 huggingface dataset:
Mid-infrared absorption spectroscopy across a 14.4THz spectral range using a broadband femtosecond optical parametric oscillator
Authors: Tillman K. A. , Maier R. R. J. , Reid D. T. , McNaghten E. D.
Published: October 2004

We describe the implementation of optical absorption spectroscopy in which a Ti:sapphire pumped femtosecond optical parametric oscillator based on periodically poled lithium niobate was used as a broadband source to directly acquire a midinfrared absorption spectrum of methane gas. Fourier-transform spectroscopy was performed using the idler output from the optical parametric oscillator to directly acquire spectra spanning over 600nm (14.4THz or 480cm−1) with around 3nm (78GHz or 2.6cm−1) resolution. This approach combines the advantages of spectroscopy using broadband thermal sources with the high power and excellent beam quality of a mode-locked laser source.
Efficient single-layer “twistacene”-doped polymer white light-emitting diodes
Authors: Xu Qianfei , Duong Hieu M. , Wudl Fred , Yang Yang
Published: October 2004

Bright, efficient, and stable white polymer light-emitting diodes based on blue polyfluorene doped by a “twistacene,” 6, 8, 15, 17-tetraphenyl-1.18, 4.5, 9.10, 13.14-tetrabenzoheptacene (3) (TBH), are demonstrated. In “twistacene” the terminal pyrene moieties serve two functions: (i) to stabilize the inherently unstable heptacene and (ii) to enable the oligoacene to be a strongly fluorescent molecule. As a result, efficient and very bright white polymer light-emitting diodes are obtained. The maximum luminance of the devices exceeds 20000cd∕m2. The maximum luminous efficiency is 3.55cd∕A at 4228cd∕m2 while the maximum power efficiency is 1.6lm∕W at 310cd∕m2. The device obtains a stable white balance by a combination of energy transfer from the blue polyfluorene to TBH by 1% TBH doping plus the host emission. The device emission color is not a function of bias current, which is ideal for various applications, from lighting to the backlight for liquid crystal displays.
Si
∕
ZnS
and Si∕ZnSe core/shell nanocrystal structures
Authors: Hu J. Q. , Bando Y. , Zhan J. H. , Golberg D.
Published: October 2004

We report on the synthesis of the Si∕ZnS and Si∕ZnSe core/shell nanocrystal structures produced via a two-stage thermal evaporation of SiO and ZnS or SiO and ZnSe powder mixtures. These core/shell structures display spherical and elliptical polycrystalline particles. Most of the Si∕ZnS core/shell nanocrystal structures have diameters of ∼90–160nm; the diameters of the cores and the thicknesses of the shells vary in a range of ∼50–100nm. The diameters of the Si∕ZnSe core/shell nanocrystal structures range from ∼150 to ∼200nm; the thicknesses of the shells are rather uniform, ∼30nm, and the diameters of the cores are thus in the range of ∼120–170nm. Room-temperature photoluminescence was also investigated from as-synthesized Si/ZnS and Si/ZnSe core/shell nanocrystal structures, respectively.
Suppressed surface morphology instabilities in amorphous hydrogenated silicon deposition
Authors: Dalakos George T. , Plawsky Joel L. , Persans Peter D.
Published: October 2004

The surface chemistry associated with a-Si:H growth by plasma-enhanced chemical vapor deposition is unique in that the hydrogen-passivated surface results in a low threshold energy for surface diffusion relative to the cohesive energies of the material. We show that helium ion bombardment enhances the hopping rate of loosely bound film precursors without substantially affecting the condensed a-Si:H material. Our investigative approach consists of examination of the temporal evolution of the surface topography under different substrate bias conditions. Without biasing the substrate, the surface morphology becomes unstable, producing mounded-type structures, consistent with shadowing growth instability. Biasing the substrate suppresses these instabilities and allows an initially rough a-Si:H surface to be smoothed during subsequent deposition.
Multiple layer local oxidation for fabricating semiconductor nanostructures
Authors: Sigrist M. , Fuhrer A. , Ihn T. , Ensslin K. , Driscoll D. C. , Gossard A. C.
Published: October 2004

Coupled semiconductor nanostructures with a high degree of tunability are fabricated using local oxidation with a scanning force microscope. Direct oxidation of the GaAs surface of a Ga[Al]As heterostructure containing a shallow two-dimensional electron gas is combined with the local oxidation of a thin titanium film evaporated on top. A four-terminal quantum dot and a double quantum dot system with integrated charge readout are realized. The structures are tunable via in-plane gates formed by isolated regions in the electron gas and by mutually isolated regions of the Ti film acting as top gates. Coulomb blockade experiments demonstrate the high quality of this fabrication process.
Simultaneity Constancy
Authors: Kopinska Agnieszka , Harris Laurence R
Published: October 2004

Sound and light take different amounts of time to reach their respective receptors, to be transduced, and to be transmitted to the cortex. Their processing times also vary with factors such as intensity and retinal eccentricity. We assessed the capability of subjects to perceive simultaneity correctly despite these variations. Temporal asynchronies of up to 200 ms were introduced between the components of sound/light pairs. Using the method of constant stimuli, seven subjects judged which came first. Distance, and hence the times of arrival of paired visual and auditory targets, was varied from 1 to 32 m. Visual intensity was varied by viewing the target through 1.8 dB attenuating glasses, and a retinal eccentricity of 20° was compared to central presentation. Despite large differences in reaction times, which varied in a predictable way with the stimulus parameters, the timing of sound/light pairings judged as simultaneous corresponded to when the light and sound left the source simultaneously. Almost complete compensation was found in all conditions tested, showing that these substantial but predictable variations in timing can be taken into account in creating simultaneity constancy.
The contribution of lateral rooting to phosphorus acquisition efficiency in maize (Zea mays) seedlings
Authors: Zhu Jinming , Lynch Jonathan P.
Published: October 2004

Low soil phosphorus availability is a primary constraint for plant growth in many terrestrial ecosystems. Lateral root initiation and elongation may play an important role in the uptake of immobile nutrients, such as phosphorus, by increasing soil exploration and phosphorus solubilisation. The overall objective of this study was to assess the value of lateral rooting for phosphorus acquisition through assessment of the ‘benefit’ of lateral rooting for phosphorus uptake and the ‘cost’ of lateral roots in terms of root respiration and phosphorus investment at low and high phosphorus availability. Five recombinant inbred lines (RILs) of maize derived from a cross between B73 and Mo17 with contrasting lateral rooting were grown in sand culture in a controlled environment. Genotypes with enhanced or sustained lateral rooting at low phosphorus availability had greater phosphorus acquisition, biomass accumulation, and relative growth rate (RGR) than genotypes with reduced lateral rooting at low phosphorus availability. The association of lateral root development and plant biomass accumulation under phosphorus stress was not caused by allometry. Genotypes varied in the phosphorus investment required for lateral root elongation, owing to genetic differences in specific root length (SRL, which was correlated with root diameter) and phosphorus concentration of lateral roots. Lateral root extension required less biomass and phosphorus investment than the extension of other root types. Relative growth rate was negatively correlated with specific root respiration, supporting the hypothesis that root carbon costs are an important aspect of adaptation to low phosphorus availability. Two distinct cost–benefit analyses, one with phosphorus acquisition rate as a benefit and root respiration as a cost, the other with plant phosphorus accumulation as a benefit and phosphorus allocation to lateral roots as a cost, both showed that lateral rooting was advantageous under conditions of low phosphorus availability. Our data suggest that enhanced lateral rooting under phosphorus stress may be harnessed as a useful trait for the selection and breeding of more phosphorus-efficient maize genotypes.
The history of Solidago canadensis invasion and the development of its mycorrhizal associations in newly-reclaimed land
Authors: Jin Liang , Gu Yongjian , Xiao Ming , Chen Jiakuan , Li Bo
Published: October 2004

This study examined the associations between an invasive alien plant (Solidago canadensis L.) and arbuscular mycorrhizal fungi (AMF) in relation to the invasion history of S. canadensis on Chongming Island, China. A significant positive correlation was found between invasion time and AMF colonisation rate. The total number of AMF species increased with increasing invasion time and was positively related to the number of plant species occurring in plant communities, suggesting that the invasion time and plant diversity influence the diversity of AMF species. The relative abundance of two dominant AMF species, Glomus mosseae and G. constrictum, varied systematically with invasion time. In dry habitats, the relative abundance of G. mosseae increased with the invasion time of S. canadensis, while that of G. constrictum decreased with the invasion time. However, these relationships did not exist in the wet habitats. Our results suggest that certain AMF species might have helped S. canadensis colonise newly-reclaimed habitats and that succession of belowground AMF communities may occur concomitantly with the development of the aboveground plant communities.
Kiwifruit L-galactose dehydrogenase: molecular, biochemical and physiological aspects of the enzyme
Authors: Laing William A , Frearson Nicky , Bulley Sean , MacRae Elspeth
Published: October 2004

l-Galactose dehydrogenase, an enzyme in the pathway of ascorbate biosynthesis, was purified to homogeneity from leaves of kiwifruit [Actinidia deliciosa (A.Chev.) CF Liang et AR Ferguson var. deliciosa ‘Hayward’]. The enzyme had a molecular mass of 34.2 kD, and behaved as a monomer during gel filtration. The Km(galactose) and Km(NAD) decreased as pH increased from 6.5 to 9, while the Vmax increased over this range. A number of related sugars were tested as alternative substrates or inhibitors, but these were ineffective. Ascorbate caused slow inactivation of the enzyme, possibly through metal catalysed generation of oxygen radicals. Inactivation appeared to be active-site directed as it was protected by the substrate NAD, and not by NADH or l-galactose. This is not likely to be physiologically significant. Through partially sequencing the protein, the gene was identified in the HortResearch Actinidia EST database, and the translation of the full length sequence of this cDNA showed a high homology (80% identity, 90% similarity) to the translation of an Arabidopsis gene (accession CAD10386) and to translations of other genes identified in GenBank. Levels of l-GalDH activity decreased during fruit and leaf development, and levels of mRNA showed a similar reduction. Activity varied between flower parts, with ovaries and styles showing equivalent activity to young fruitlets and sink leaves. Nucleotide sequences reported are available in the Genbank database under the accession number AY176585 (kiwifruit) and AY264803 (apple).
Crystal structure of the dimeric protein core of decorin, the archetypal small leucine-rich repeat proteoglycan
Authors: Scott Paul G. , McEwan Paul A. , Dodd Carole M. , Bergmann Ernst M. , Bishop Paul N. , Bella Jordi
Published: October 2004

Decorin is a ubiquitous extracellular matrix proteoglycan with a variety of important biological functions that are mediated by its interactions with extracellular matrix proteins, cytokines, and cell surface receptors. Decorin is the prototype of the family of small leucine-rich repeat proteoglycans and proteins (SLRPs), characterized by a protein core composed of leucine-rich repeats (LRRs), flanked by two cysteine-rich regions. We report here the crystal structure of the dimeric protein core of decorin, the best characterized member of the SLRP family. Each monomer adopts the curved solenoid fold characteristic of LRR domains, with a parallel β-sheet on the inside interwoven with loops containing short segments of β-strands, 3
10
helices, and polyproline II helices on the outside. Two main features are unique to this structure. First, decorin dimerizes through the concave surfaces of the LRR domains, which have been implicated previously in protein-ligand interactions. The amount of surface buried in this dimer rivals the buried surfaces of some of the highest-affinity macromolecular complexes reported to date. Second, the C-terminal region adopts an unusual capping motif that involves a laterally extended LRR and a disulfide bond. This motif seems to be unique to SLRPs and has not been observed in any other LRR protein structure to date. Possible implications of these features for decorin ligand binding and SLRP function are discussed.
Association of Hepatitis C with Posttransplant Diabetes in Renal Transplant Patients on Tacrolimus
Authors: Bloom Roy D. , Rao Vinaya , Weng Francis , Grossman Robert A. , Cohen Debbie , Mange Kevin C.
Published: October 2004

Posttransplant diabetes mellitus (PTDM) remains a common complication of immunosuppression. Although multiple risk factors have been implicated, none have been clearly identified as predisposing to the increased PTDM frequency observed in patients on tacrolimus. Hepatitis C virus (HCV) has been associated with diabetes and is a significant renal transplant comorbidity. In this study, records of 427 kidney recipients who had no known diabetes before transplantation were retrospectively examined. A multivariate logistic regression model was fit with covariates that had unadjusted relationships with PTDM to examine the independent relationship of HCV and the odds of development of PTDM by 12 mo posttransplant. A potential interaction between HCV and the use of tacrolimus as maintenance therapy on the odds of the development of PTDM was examined. Overall, PTDM occurred more frequently in HCV+ than HCV− patients (39.4% versus 9.8%; P = 0.0005). By multivariate logistic regression, HCV (adjusted odds ratio [OR], 5.58; 95% confidence interval [CI], 2.63 to 11.83; P = 0.0001), weight at transplantation (adjusted OR 1.028; 95% CI, 1.00 to 1.05; P = 0.001), and tacrolimus (adjusted OR, 2.85; 95% CI, 1.01 to 5.28; P = 0.047) were associated with PTDM. A significant interaction (P = 0.0001) was detected between HCV status and tacrolimus use for the odds of PTDM. Among the HCV+ cohort, PTDM occurred more often in tacrolimus-treated than cyclosporine A–treated patients (57.8% versus 7.7%; P < 0.0001). PTDM rates in HCV− patients were similar between the two calcineurin inhibitors (10.0% versus 9.4%; P = 0.521, tacrolimus versus cyclosporine A). In conclusion, HCV is strongly associated with PTDM in renal transplant recipients and appears to account for the increased diabetogenicity observed with tacrolimus.
Angiotensin II Directly Stimulates ENaC Activity in the Cortical Collecting Duct via AT1 Receptors
Authors: Peti-Peterdi János , Warnock David G. , Bell P. Darwin
Published: October 2004

Angiotensin II (AngII) helps to regulate overall renal tubular reabsorption of salt and water, yet its effects in the distal nephron have not been well studied. The purpose of these studies was to determine whether AngII stimulates luminal Na+ transport in the cortical collecting duct (CCD). Intracellular Na+ concentration ([Na+]i), as a reflection of Na+ transport across the apical membrane, was measured with fluorescence microscopy using sodium-binding benzofuran isophthalate (SBFI) in isolated, perfused CCD segments dissected from rabbit kidneys. Control [Na+]i, during perfusion with 25 mM NaCl and a Na+-free solution in the bath containing the Na+-ionophore monensin (10 μM, to eliminate basolateral membrane Na+ transport) averaged 19.3 ± 5.2 mM (n = 16). Increasing luminal [NaCl] to 150 mM elevated [Na+]i by 9.87 ± 1.5 mM (n = 7; P < 0.05). AngII (10−9 M) added to the lumen significantly elevated baseline [Na+]i by 6.3 ± 1.0 mM and increased the magnitude (Δ = 25.2 ± 3.7 mM) and initial rate (≈5 fold) of change in [Na+]i to increased luminal [NaCl]. AngII when added to the bath had similar stimulatory effects; however, AngII was much more effective from the lumen. Thus, AngII significantly increased the apical entry of Na+ in the CCD. To determine if this apical entry step occurred via the epithelial Na+ channel (ENaC), studies were performed using the specific ENaC blocker, benzamil hydrochloride (10−6 M). When added to the perfusate, benzamil almost completely inhibited the elevations in [Na+]i to increased luminal [NaCl] in both the presence and absence of AngII. These results suggest that AngII directly stimulates Na+ channel activity in the CCD. AT1 receptor blockade with candesartan or losartan (10−6 M) prevented the stimulatory effects of AngII. Regulation of ENaC activity by AngII may play an important role in distal Na+ reabsorption in health and disease.
The Position of the Polycystic Kidney Disease 1 (PKD1) Gene Mutation Correlates with the Severity of Renal Disease
Authors: Rossetti Sandro , Burton Sarah , Strmecki Lana , Pond Gregory R. , San Millán Jośe L. , Zerres Klaus , Barratt T. Martin , Ozen Seza , Torres Vicente E. , Bergstralh Erik J. , Winearls Christopher G. , Harris Peter C.
Published: October 2004

The severity of renal cystic disease in the major form of autosomal dominant polycystic kidney disease (PKD1) is highly variable. Clinical data was analyzed from 324 mutation-characterized PKD1 patients (80 families) to document factors associated with the renal outcome. The mean age to end-stage renal disease (ESRD) was 54 yr, with no significant difference between men and women and no association with the angiotensin-converting enzyme polymorphism. Considerable intrafamilial variability was observed, reflecting the influences of genetic modifiers and environmental factors. However, significant differences in outcome were also found among families, with rare examples of unusually late-onset PKD1. Possible phenotype/genotype correlations were evaluated by estimating the effects of covariants on the time to ESRD using proportional hazards models. In the total population, the location of the mutation (in relation to the median position; nucleotide 7812), but not the type, was associated with the age at onset of ESRD. Patients with mutations in the 5′ region had significantly more severe disease than the 3′ group; median time to ESRD was 53 and 56 yr, respectively (P = 0.025), with less than half the chance of adequate renal function at 60 yr (18.9% and 39.7%, respectively). This study has shown that the position of the PKD1 mutation is significantly associated with earlier ESRD and questions whether PKD1 mutations simply inactivate all products of the gene.
Mesangial Cell-Binding Anti-DNA Antibodies in Patients with Systemic Lupus Erythematosus
Authors: Chan Tak-Mao , Leung Jack Kok-Hung , Ho Stephen Kar-Nung , Yung Susan
Published: October 2004

The mechanisms by which anti-DNA antibodies contribute to the pathogenesis of lupus nephritis (LN) remain to be elucidated. This study investigates the binding of polyclonal anti-DNA immunoglobulins from patients with systemic lupus erythematosus (SLE) to human mesangial cells (HMC) in vitro. Testing of cross-sectional serum samples from 280 LN patients (108 during active disease; 172 during remission), 35 SLE patients without renal involvement, 72 patients with non-lupus primary glomerular diseases, and 37 healthy subjects with a cellular enzyme-linked immunosorbent assay showed significant IgG mesangial cell-binding activity in patients with SLE, particularly those with active LN (P < 0.0001). Significant HMC-binding activity was demonstrated in 83.9%, 42.8%, and 47.1% of patients with active LN, inactive LN, and non-renal SLE, respectively. This was predominantly attributed to binding by anti-DNA antibodies, and immune complex binding accounted for 4.6%, 3.5%, and 2.8% of seropositive samples in the respective groups. Longitudinal studies in 27 LN patients demonstrated correlation between serial levels of anti-DNA antibodies, serum HMC-binding activity, and disease activity in 18 patients (66.7%). Affinity-purified polyclonal IgG anti-DNA antibodies from sera with HMC-binding activity showed significant binding to cultured HMC, and to a lesser extent glomerular and proximal tubular epithelial cells and human umbilical vein endothelial cells, but not tumor cell lines, peritoneal mesothelial cells, bronchial epithelial cells, or fibroblasts. The binding of anti-DNA antibodies to HMC was increased 1.47-fold (P = 0.0059) after the removal of Ig-associated DNA by DNase treatment, but it was unaffected by DNase treatment of HMC membrane. Controlled trypsinization of membrane proteins in HMC resulted in a 1.26-fold (P = 0.0025) increase in their binding by anti-DNA antibodies. In conclusion, subsets of anti-DNA antibodies from patients with SLE are capable of binding to HMC. The association of such binding with renal involvement and disease activity and its modulation by DNA concentration suggest that Ig binding to HMC can be a potential marker for disease activity in selected patients and that the binding of anti-DNA antibodies to HMC may be a pathogenetic mechanism in LN.
Racial Differences in the Progression from Chronic Renal Insufficiency to End-Stage Renal Disease in the United States
Authors: Hsu Chi-yuan , Lin Feng , Vittinghoff Eric , Shlipak Michael G
Published: October 2004

Black Americans experience a disproportionate burden of ESRD compared with whites. Whether this is caused by the increased prevalence of chronic renal insufficiency (CRI) among blacks or by their increased progression from CRI to ESRD was investigated. A birth cohort analysis was performed using data from the Third National Health and Nutrition Examination Survey and the United States Renal Data System. It was assumed that those who developed ESRD in 1996 aged 25 to 79 yr came from the source population with CRI aged 20 to 74 yr that was sampled in the Third National Health and Nutrition Examination Survey (midpoint 1991). GFR was estimated using the Modification of Diet in Renal Disease study equation. The prevalence of CRI (GFR 15 to 59 ml/min per 1.73 m2) was not different among black compared with white adults (2060 versus 2520 per 100,000; P = 0.14). For each 100 blacks with CRI in 1991, five new cases of ESRD developed in 1996, whereas only one case of ESRD developed per 100 whites with CRI (risk ratio, 4.8; 95% confidence interval, 2.9 to 8.4). The increased risk for blacks compared with whites was only modestly affected by adjustment for age, gender, and diabetes. Blacks with CRI had higher systolic (147 versus 136 mmHg; P = 0.001) and diastolic (82 versus 77 mmHg; P = 0.02) BP and greater albuminuria (422 versus 158 μg urine albumin/mg urine creatinine; P = 0.01). The higher incidence of ESRD among blacks is not due to a greater prevalence of CRI among blacks. The key to understanding black–white differences in ESRD incidence lies in understanding the extreme differences in their progression from CRI to ESRD. E-mail: hsuchi@medicine.ucsf.edu
The Fine Specificity and Cytokine Profile of T-Helper Cells Responsive to the α3 Chain of Type IV Collagen in Goodpasture’s Disease
Authors: Cairns Lindsay S. , Phelps Richard G. , Bowie Laura , Hall Andrew M. , Saweirs Walaa W.M. , Rees Andrew J. , Barker Robert N.
Published: October 2004

Goodpasture’s disease is a severe nephritis characterized by autoantibodies to the α3 chain of type IV collagen, α3(IV)NC1, in the glomerular basement membrane. The disease is very strongly associated with HLA-DR15, the affinities of α3(IV)NC1 peptides for DR15 are known, and elution experiments have identified major naturally processed sequences. Here, the fine specificity and cytokine profile of α3(IV)NC1-reactive T cells from patients with Goodpasture’s disease is defined. Peripheral blood mononuclear cells from patients at diagnosis proliferated in response to significantly more peptides (χ2 = 8.6, P = 0.004) from a panel spanning the sequence of α3(IV)NC1 than did those from control DR15-positive donors and were highly focused (P = 0.0002, binomial distribution) on two peptides, α371–90 and α3131–150. Some peptides induced interferon-γ, but none induced IL-4. Resolution of disease was accompanied by a striking deviation of the responses from proliferation to secretion of the T-regulatory cytokine IL-10, and addition of neutralizing antibody confirmed that such IL-10 production was suppressive. The affinity of the peptides for DR15 molecules was positively correlated (χ2 = 14.6, P = 0.00067) with the ability to elicit proliferation. However, unlike foreign antigens, this hierarchy is not due to responses against the major naturally processed peptides, which rarely stimulated proliferation and which have only intermediate affinity for DR15 molecules. It is inferred that the helper response to α3(IV)NC1 in Goodpasture’s disease is dominated by epitopes that are normally inefficiently presented because of processing constraints. E-mail: r.n.barker@abdn.ac.uk
Association of High Serum Creatinine and Anemia Increases the Risk of Coronary Events
Authors: Jurkovitz Claudine T. , Abramson Jerome L. , Vaccarino L. Viola , Weintraub William S. , McClellan William M.
Published: October 2004

Coronary heart disease (CHD) is a major cause of morbidity and mortality in patients with chronic kidney disease or anemia. The purpose of this study was to examine whether the association between renal function and risk of CHD is modified by hemoglobin (Hgb) status. Analyses were based on data from the Atherosclerosis Risk in Communities study, a community-based study of risk factors for CHD in middle-aged people. People with known CHD at baseline were excluded from the analysis. Participants were followed for 9 yr for the occurrence of CHD. Anemia was defined as Hgb <13 g/dl in men and <12 g/dl in women. Cox proportional hazards models were used to assess the relative risk (RR) of CHD occurrence according to Hgb status, after adjusting for other risk factors (demographics, lipids, diabetes, hypertension, smoking, body mass index, and carotid intima-media thickness). A total of 13,329 participants were included. The interaction between Hgb concentration and serum creatinine (Scr) was significant (P = 0.02). Among people with anemia, a Scr ≥1.2 mg/dl in women or ≥1.5 mg/dl in men was associated with a higher risk of CHD (RR, 2.74; 95% confidence interval, 1.42 to 5.28) than those with normal Scr. In contrast, among those without anemia, this association was not noted (RR, 1.20; 95% confidence interval, 0.86 to 1.67). In conclusion, this study indicates that high Scr is associated with almost a threefold risk of CHD among middle-aged people with anemia, whereas no increased risk is found in people with high Scr in the absence of anemia. E-mail: cjurkov@emory.edu
Preventing Bone Loss in Renal Transplant Recipients with Vitamin D
Authors: El-Agroudy Amgad E. , El-Husseini Amr A. , El-Sayed Moharam , Ghoneim Mohamed A.
Published: October 2004

Very rapid bone loss, osteopenia, and osteoporosis have been documented in the first 6 to 12 mo after renal transplantation. Investigated was the effect of treatment with active vitamin D on the prevention of posttransplantation bone loss. Forty adult men who were recent renal transplant recipients were enrolled onto the study. Patients were randomized into two groups: group 1 received daily alfacalcidol 0.5 μg by mouth, and group 2 (control) received placebo. Every patient in both groups received daily 500-mg calcium carbonate supplements. Parameters of bone metabolism and bone mineral density measured at three sites were assessed before and after the study period. Bone mineral density was increased by 2.1%, 1.8%, and 3.2% at lumbar spine, femoral neck, and forearm, respectively, in group 1, whereas it decreased by 3.2%, 3.8%, and 1.8% at the same sites in the control group (P < 0.05). Serum intact parathyroid hormone level decreased significantly in group 1 compared with the control group (P = 0.003). Early bone loss that occurs during the first 1 yr after renal transplantation could be prevented by alfacalcidol. Use of alfacalcidol early after transplantation is safe and well tolerated. E-mail: amgadelbaz@ahram0505.net
High Proteinase 3-Anti-Neutrophil Cytoplasmic Antibody (ANCA) Level Measured by the Capture Enzyme-Linked Immunosorbent Assay Method Is Associated with Decreased Patient Survival in ANCA-Associated Vasculitis with Renal Involvement
Authors: Westman Kerstin W. A. , Selga Daina , Isberg Per-Erik , Bladström Anna , Olsson Ha[Combining Ring Above]kan
Published: October 2004

Wegener granulomatosis (WG) and microscopic polyangiitis (MP), diseases associated with antineutrophil cytoplasmic antibodies (ANCA), had an extremely poor prognosis before the introduction of cyclophosphamide and corticosteroids for their treatment. However, there is still reduced patient survival, and some studies have documented severe side effects of the immunosuppressants used. This 10-yr follow-up study assessed 117 consecutive patients with WG or MP with biopsy-confirmed renal involvement. The cumulative relative patient survival was lower: 0.664 for women and 0.648 for men. The causes of death (n = 64) were in most cases registered as associated with the vasculitic disease. Analysis of possible predictive factors for patient survival by multiple Cox regression analysis revealed that a very high level of proteinase 3 (PR3)-ANCA measured by the capture ELISA method, a diagnosis of MP, and older age were factors predicting poorer patient survival. High levels of B-thrombocytes at time of diagnosis were associated with a better prognosis. For patients surviving the first year, remission-sustaining therapy with azathioprine for longer than 12 mo was associated with improved patient survival. Thirty-nine patients developed end-stage renal failure. Elevated serum creatinine at time of diagnosis and a very high level of PR3-ANCA by capture ELISA were factors predicting a higher risk for renal failure during follow-up. The epitope on PR3 assessed by capture ELISA needs to be further analyzed and explored: it seemed to implicate poorer patient and renal survival in WG or MP with renal involvement. E-mail: kerstin.westman@ skane.se
Risk Factors for Chronic Kidney Disease
Authors: Haroun Melanie K. , Jaar Bernard G. , Hoffman Sandra C. , Comstock George W. , Klag Michael J. , Coresh Josef
Published: October 2004

Chronic kidney disease (CKD) is an increasing cause of morbidity and mortality in the United States. Prospective data on risk factors for CKD are limited to men, and few studies examine the importance of smoking. The authors performed a community-based, prospective observational study of 20-yr duration to examine the association between hypertension and smoking on the future risk of CKD in 23,534 men and women in Washington County, Maryland. CKD was identified as end-stage renal disease in the Health Care Financing Administration database or kidney disease listed on the death certificate. All cases were confirmed as CKD by medical chart review. Adjusted relative hazards of CKD were modeled using Cox proportional hazards regression including age as the time variable and baseline BP, cigarette smoking, gender, and diabetes status as risk factors. The adjusted hazard ratio (95% confidence interval) of developing CKD among women was 2.5 (0.05 to 12.0) for normal BP, 3.0 (0.6 to 14.4) for high-normal BP, 3.8 (0.8 to 17.2) for stage 1 hypertension, 6.3 (1.3 to 29.0) for stage 2 hypertension, and 8.8 (1.8 to 43.0) for stages 3 or 4 hypertension compared with individuals with optimal BP. In men, the relationship was similar but somewhat weaker than in women, with corresponding hazard ratios of 1.4 (0.2 to 12.1), 3.3 (0.4 to 25.6), 3.0 (0.4 to 22.2), 5.7 (0.8 to 43.0), and 9.7 (1.2 to 75.6), respectively. Current cigarette smoking was also significantly associated with risk of CKD in both men and women (hazard ratio in women 2.9 [1.7 to 5.0] and in men 2.4 [1.5 to 4.0]). A large proportion of the attributable risk of CKD in this population was associated with stage 1 hypertension (23%) and cigarette smoking (31%). In conclusion, CKD risk shows strong graded relationships to the sixth report of the Joint National Committee (JNC-VI) on Prevention, Detection Evaluation and Treatment of High BP criteria for BP, to diabetes, and to current cigarette smoking that are at least as strong in women as in men. E-mail: coresh@jhu.edu
O2microsensors for minimally invasive tissue monitoring
Authors: Wang W. , Vadgama P.
Published: October 2004

Tissue oxygenation is a key factor ensuring normal tissue functions and viability. Continuous real-time monitoring of the partial pressure of oxygen,pO2, in tissues gives insight into the dynamic fluctuations of O2supplies to tissues by blood circulation. Small oxygen sensors enable investigations of the spatial variation ofpO2in tissues at different locations in relation to local microvessels. In this paper,pO2measurement using microelectrodes and biocompatible sensors is discussed and recent progress of their application in human skin is reviewed. Emphasis is given to working principles of a number of existing oxygen sensors and their potential application in vivo and in tissue engineering. Results on spatial and temporal variations of thepO2in human skin introduced by localized ischaemia-reperfusion are presented when the surface of the skin is covered by an oxygen-free paraffin oil layer and the range of the tissuepO2is deduced to be between 0 and 60 mmHg. In the study,pO2increases from 8.0±3.2 mmHg (n=6) at the surface of the skin to 35.2±8.0 mmHg (n=9) at a depth just above the subpapillary plexus. Temporal decay inpO2following tissue compression and rise inpO2following pressure release can be described using mono-exponential functions. The time constant for the exponential decay,t=8.44±1.53 s (n=7) is consistently greater than that for the exponential rises,τ′=4.75±0.82 s (n=6). The difference inpO2change with the time following tissue compression and pressure release reveals different dynamic mechanisms involved in the two transient phases. The elevated steady statepO2following reperfusion, which is approximately 20% higher than the pre-occlusion value, indicates localized reactive hyperaemia. Possible applications of O2microsensors in diseases, e.g. tumours, pressure ulcers, are also discussed.
Comparable worth in a decentralized labour market: the case of Ontario
Authors: Baker Michael , Fortin Nicole M.
Published: October 2004

Abstract.  We document the application of pro‐active pay equity legislation to the private sector of the Canadian province of Ontario in the early 1990s. We report substantial lapses in compliance among smaller firms where the majority of men and women work. We also find that the pay equity law had no effect on aggregate wages in female jobs or on the gender wage gap. This experience provides unique perspectives on (1) the tensions between the workings of a decentralized labour market and the principles of comparable worth and (2) the obstacles to its extension to the private sector. JEL classification: J7, J3
Family income and child outcomes in Canada
Authors: Dooley Martin , Stewart Jennifer
Published: October 2004

Abstract.  A positive relationship between income and child outcomes has been observed in data from numerous countries. A key question concerns the extent to which this association represents a causal relationship as opposed to unobserved heterogeneity. We use data from the National Longitudinal Survey of Children and Youth to implement a series of empirical strategies for estimating the existence and size of the effect of income on three measures of cognition. Our results indicate that the effect of income on these outcomes may well be positive, but that it is likely to be smaller than conventional estimates. JEL Classification: I10
Multidivisional firms, internal competition, and the merger paradox
Authors: Creane Anthony , Davidson Carl
Published: October 2004

Abstract.  Traditional modelling of mergers has the merged firms (insiders) cooperate and maximize joint profits. This approach has several unappealing results in quantity‐setting games, for example, mergers typically are not profitable for insiders, but are profitable for non‐merging firms (outsiders). We take a different approach and allow for a parent company that can play each insider off one another. In quantity‐setting games, with our approach mergers are profitable for insiders, unprofitable for outsiders, socially beneficial, and involve (in a non‐monopolizing merger) a small number of firms. Finally, we find that the optimal strategy depends on whether firms compete in quantity or prices. JEL classification: L000
Price stickiness, trend inflation, and output dynamics: a cross‐country analysis
Authors: Khan Hashmat
Published: October 2004

Abstract.  Sticky price models based on menu costs predict that countries with high trend inflation should have (i) smaller impact effects of demand shocks on output and (ii) less persistent output fluctuations, relative to low‐trend inflation countries. These predictions are tested, controlling for changes in trend inflation, using a country‐specific approach. The results do not support the second prediction. That prediction is also not robust to a modified measure of trend inflation that excludes episodes of hyperinflation. These findings suggest that while price stickiness is important for understanding short‐run impact effects, real propagation mechanisms may drive persistence in output fluctuations.
Trade, product cycles, and inequality within and between countries
Authors: Chun Zhu Susan
Published: October 2004

Abstract.  This paper incorporates Northern product innovation and product‐cycle‐driven technology transfer into the continuum‐of‐goods Heckscher‐Ohlin model. The creation of very skill‐intensive goods induces the North to transfer production of older, less skill‐intensive goods to the South. These relocated goods are the most skill intensive by Southern standards. Hence, product cycles raise the relative demand for skilled workers and thus wage inequality within both regions. This runs contrary to the Stolper‐Samuelson theorem, but accords well with the fact that wage inequality has risen in both Northern and Southern countries. Moreover, product cycles increase income inequality between countries. JEL classification: F1
Total factor productivity and the measurement of technological change
Authors: Lipsey Richard G. , Carlaw Kenneth I.
Published: October 2004

Abstract. TFP is interpreted in the literature in different, mutually contradictory ways. Changes in TFP are shown to measure not technological change, only the super‐normal returns to investing in such change – returns that exceed the full opportunity cost of the activity. Thus, in the limit, technological change can proceed with unchanged TFP. Measuring the effects of technological change instead requires counterfactual estimates. Reasons why changes in TFP are imperfect measures of super normal returns are also studied – reasons connected with the timing of output responses, the treatment of R&D in the national accounts, the omission of resource inputs, and two types of aggregation.
COMPARISON OF GROWTH AND SINKING RATES OF NON‐COCCOLITH‐ AND COCCOLITH‐FORMING STRAINS OF EMILIANIA HUXLEYI(PRYMNESIOPHYCEAE) GROWN UNDER DIFFERENT IRRADIANCES AND NITROGEN SOURCES1
Authors: Lecourt Maude , Muggli Deborah L. , Harrison Paul J.
Published: October 2004

We examined the effect of the presence or absence of coccoliths on the growth and sinking rates of an oceanic isolate of the coccolithophore Emiliania huxleyi (Lohmann) Hay et Mohler isolated from the northeastern subarctic Pacific. Coccolith‐forming and non‐coccolith‐forming (i.e. naked, nonmotile) strains were obtained from the same isolate and grown under both saturating and limiting irradiance levels with either nitrate or ammonium as the primary nitrogen source. Sinking rate, growth rate, and cell volume (excluding coccoliths) were measured for each culture. Under saturating irradiance, coccolith‐forming cells grew significantly slower than naked cells, had significantly higher sinking rates, and had larger cell volumes than naked cells. Under limiting irradiance levels, growth rates of the two strains were identical, sinking rates were higher for coccolith‐forming cells in stationary‐phase cultures only, and cell volumes remained greater for coccolith‐forming cells.

The sinking rates achieved for this ubiquitous coccolithophore ranged from <0.1 to 0.5 m · d−1. Sinking rates were not statistically different between coccolith‐forming and naked strains of E. huxleyi under limiting irradiance conditions for log‐phase cultures, but sinking rates were greater for coccolith‐forming cells under some of the other conditions tested. However, the average sinking rate was never more than twice as great as for coccolith‐forming cells, with the exception of nitrate‐grown, senescent cells under limiting irradiance (3.4 times greater). Cell volumes (excluding coccoliths) were consistently ca. 1.5 times greater for coccolith‐forming cells than for naked cells.

Nitrogen source had an effect on growth rate and cell volume, with ammonium‐grown cultures growing faster and having larger cell volumes than nitrate‐grown cultures of both strains. However, despite the difference in growth rate and cell volume, nitrogen source had little if any effect on sinking rate.
CYANOBACTERIAL BUOYANCY REGULATION: THE PARADOXICAL ROLES OF CARBON1
Authors: Klemer Andrew R. , Cullen John J. , Mageau Michael T. , Hanson Kathryn M. , Sundell Richard A.
Published: October 2004

In stratified lakes, dominance of the phytoplankton by cyanobacteria is largely the result of their buoyancy and depth regulation. Bloom‐forming cyanobacteria regulate the gas vesicle and storage polymer contents of their cells in response to interactive environmental factors, especially light and nutrients. While research on the roles of nitrogen and phosphorus in cyanobacterial buoyancy regulation has reached a consensus, evaluations of the roles of carbon have remained open to dispute. We investigated the various effects of changes in carbon availability on cyanobacterial buoyancy with continuous cultures of Microcystis aeruginosa Kuetz. emend. Elenkin (1924), a notorious bloom‐former. Although CO2 limitation of photosynthesis can promote buoyancy in the short term by preventing the collapse of turgor‐sensitive gas vesicles and/or by limiting polysaccharide accumulation, we found that sustained carbon limitation restricts buoyancy regulation by limiting gas vesicle as well as polysaccharide synthesis. These results provide an explanation for the positive effects of bicarbonate enrichment on cyanobacterial nitrogen uptake and bloom formation in lake experiments and may help to explain the pattern of cyanobacterial dominance in phosphorus‐enriched, low‐carbon lakes.
SPECIES‐SPECIFIC CHARACTERISTICS EXPLAIN THE PERSISTENCE OFSTIGEOCLONIUM TENUE(CHLOROPHYTA) IN A WOODLAND STREAM1
Authors: Rosemond Amy D. , Brawley Susan H.
Published: October 2004

The heterotrichous algaStigeoclonium tenueKüetzing is dominant in many streams with high densities of herbivores. Previousin situstudies in Walker Branch (WB), a woodland stream in eastern Tennessee, indicated that dominance byStigeocloniumbasal cells was “grazer‐dependent”; however,Stigeocloniumalso appeared to have a lower biomass–specific productivity rate than other species that dominated when snails were experimentally removed. Here, an explicit test of the grazing dependence ofStigeocloniumwas made with unialgal cultures established in the laboratory. Five different “assemblage types” were tested: 1 and 2) unialgal cultures ofStigeocloniumat low and high biomass, 3 and 4) a mixed assemblage of diatoms at low and high biomass, and 5) a natural stream community. Reduction in chlorophyllaafter exposure to snail grazing was dependent on assemblage type (one‐way ANOVA,P< 0.0001); low biomassStigeocloniumtiles and tiles from the stream (on which basal cells ofStigeocloniumwere dominant) were most grazer‐resistant. In addition,Stigeocloniumhad a lower biomass‐specific productivity rate (measured as H14CO3−uptake) than a mixed assemblage of diatoms, regardless of biomass level, suggesting an underlying tradeoff between resistance to herbivory and competitive ability. Additional laboratory experiments were conducted to determine the response ofStigeocloniumto high (approx. 150 μmol quanta ·m−2· s−1)and low (approx. 25 μmol quanta · m−2· s−1) irradiance when nutrients were at 1) ambient WB concentrations and 2) increased 1000× ambient concentrations. There was a positive response of growth to increased irradiance only under high nutrient conditions. This suggests that observed reductions in the abundance ofStigeocloniumunder high irradiance/low nutrient conditions that occur on a seasonal basis in WB can be explained in part by autecological resource requirements of this alga. We use these results to model the response of algal communities dominated by basal‐regenerating species (e.g.Stigeoclonium)to gradients in herbivory and productivity. The results of our culture studies, combined with an overview of factors affecting communities dominated by grazer‐resistant species, illustrate how both broad‐scale (e.g. functional form) and species‐specific studies can be combined to achieve an understanding of community dynamics.
EFFECTS OF HARVEST STAGE AND LIGHT ON THE BIOCHEMICAL COMPOSITION OF THE DIATOM THALASSIOSIRA PSEUDONANA1
Authors: Brown Malcolm R. , Dunstan Graeme A. , Norwood Suzanne. J. , Miller Kelly A.
Published: October 2004

The marine diatom Thalassiosira pseudonana (Hustedt, clone 3H) Hasle and Heimdal was cultured under three different light regimes: 100 μmol photon · m−2· s−1 on 12:12 h light : dark (L:D) cycles; 50 μmol photon · m−2· s−2 on 24:0 h L:D; and 100 μmol photon · m−2· s−1 on 24:0 h L:D. It was harvested during logarithmic and stationary phases for analysis of biochemical composition. Across the different light regimes, protein (as % of organic weight) was highest in cells during logarithmic phase, whereas carbohydrate and lipid were highest during stationary phase. Carbohydrate concentrations were most affected by the different light regimes; cells grown under 12:12 h L:D contained 37–44% of the carbohydrate of cells grown under 24:0 h L:D. Cells in logarithmic phase had high proportions of polar lipids (79 to 89% of total lipid) and low triacylglycerol (≤10% of total lipid). Cells in stationary phase contained less polar lipid (48 to 57% of total lipid) and more triacylglycerol (22 to 45% of total lipid). The fatty acid composition of logarithmic phase cells grown under 24:0 h L:D were similar, but the 100 μmol photon · m−2· s−1 (12:12 h L:D) cells at the same stage contained a higher proportion of polyunsaturated fatty acids (PUFAs) and a lower proportion of saturated and monounsaturated fatty acids due to different levels of 16:0, 16:1(n‐7), 16:4(n‐1), 18:4(n‐3), and 20:5(n‐3). With the onset of stationary phase, cells grown at 100 μmol photon · m−2· s−1 (both 12:12 and 24:0 h L:D) increased in proportions of saturated and monounsaturated fatty adds and decreased in PUFAs. Concentrations (% organic or dry weight) of 14:0, 16:0, 16:1(n‐7), 20:5(n‐3), and 22:6(n‐3) increased in cells of all cultures during stationary phase. The amino acid compositions of cells were similar irrespective of harvest stage and light regime. For mariculture, the recommended light regime for culturing T. pseudonana will depend on the nutritional requirements of the animal to which the alga is fed. For rapidly growing bivalve mollusc larvae, stationary‐phase cultures grown under a 24:0 h L:D regime may provide more energy by virtue of their higher percentage of carbohydrate and high proportions and concentrations of energy‐rich saturated fatty acids.