bluuebunny/crossref_metadata_2025 huggingface dataset:
Resolution of Sister Telomere Association Is Required for Progression Through Mitosis
Authors: Dynek Jasmin N. , Smith Susan
Published: April 2004

Cohesins keep sister chromatids associated from the time of their replication in S phase until the onset of anaphase. In vertebrate cells, two distinct pathways dissociate cohesins, one acts on chromosome arms and the other on centromeres. Here, we describe a third pathway that acts on telomeres. Knockdown of tankyrase 1, a telomeric poly(ADP-ribose) polymerase caused mitotic arrest. Chromosomes aligned normally on the metaphase plate but were unable to segregate. Sister chromatids separated at centromeres and arms but remained associated at telomeres, apparently through proteinaceous bridges. Thus, telomeres may require a unique tankyrase 1–dependent mechanism for sister chromatid resolution before anaphase.
Ultrafast Electron Crystallography of Interfacial Water
Authors: Ruan Chong-Yu , Lobastov Vladimir A. , Vigliotti Franco , Chen Songye , Zewail Ahmed H.
Published: April 2004

We report direct determination of the structures and dynamics of interfacial water on a hydrophilic surface with atomic-scale resolution using ultrafast electron crystallography. On the nanometer scale, we observed the coexistence of ordered surface water and crystallite-like ice structures, evident in the superposition of Bragg spots and Debye-Scherrer rings. The structures were determined to be dominantly cubic, but each undergoes different dynamics after the ultrafast substrate temperature jump. From changes in local bond distances (OH··O and O···O) with time, we elucidated the structural changes in the far-from-equilibrium regime at short times and near-equilibration at long times.
Seeing Through the Steam of Consciousness
Authors: Haggard Patrick
Published: April 2004

The Quest for Consciousness
A Neurobiological Approach.
Christof Koch
. Roberts, Englewood, CO, 2004. 447 pp. $45, £29.99. ISBN 0-9747077-0-8.

Using the neuronal correlates of consciousness framework that he and Frances Crick have constructed, Koch explores the biological basis of the subjective mind in humans and other animals.
Risk factors, prevalence, and treatment of anxiety and depressive disorders in Pakistan: systematic review
Authors: Mirza Ilyas , Jenkins Rachel
Published: April 2004

Objectives To assess the available evidence on the prevalence, aetiology, treatment, and prevention of anxiety and depressive disorders in Pakistan.

Design Systematic review of published literature.

Studies reviewed 20 studies, of which 17 gave prevalence estimates and 11 discussed risk factors.

Main outcome measures Prevalence of anxiety and depressive disorders, risk factors, effects of treatment.

Results Factors positively associated with anxiety and depressive disorders were female sex, middle age, low level of education, financial difficulty, being a housewife, and relationship problems. Arguments with husbands and relational problems with in-laws were positively associated in 3/11 studies. Those who had close confiding relationships were less likely to have anxiety and depressive disorders. Mean overall prevalence of anxiety and depressive disorders in the community population was 34% (range 29-66% for women and 10-33% for men). There were no rigorously controlled trials of treatments for these disorders.

Conclusions Available evidence suggests a major social cause for anxiety and depressive disorders in Pakistan. This evidence is limited because of methodological problems, so caution must be exercised in generalising this to the whole of the population of Pakistan.
Syntheses of novel modified acyclic purine and pyrimidine nucleosides as potential substrates of herpes simplex virus type-1 thymidine kinase for monitoring gene expression
Authors: Grote Michaela , Noll Steffi , Noll Bernhard , Johannsen Bernd , Kraus Werner
Published: April 2004

Suicide gene therapy with the herpes simplex virus type-1 thymidine kinase gene (HSV-1 tk) is considered to be a promising approach to the treatment of cancer. Making use of the lower specificity of the viral enzyme compared to human thymidine kinase, the therapy involves the administration of antiviral agents (e.g., ganciclovir) as prodrugs to induce enzymatic cell death in those cells that express the transferred gene. 18F-labelled derivatives have been described for monitoring location, duration, and magnitude of the viral kinase enzyme activity by positron emission tomography (PET). Since an optimal radiotracer has not been developed, novel substances were synthesized for monitoring gene expression. A group of 13 nucleoside analogues were synthesized, among them N1-methyl-9-[(1,3-dihydroxy-2-propoxy)methyl]guanine (5) and N1-methyl-9-[(4-hydroxy)-3-hydroxymethylbutyl]guanine (7) as methyl analogues of ganciclovir and penciclovir and their related fluoro compounds (6, 8). Further novel derivatives include N6-methyl-9-[(1,3-dihydroxy-2-propoxy)methyl]-, N6-methyl-9-[(4-hydroxy)-3-hydroxymethylbutyl]adenine (9, 10), as well as the uracil derivatives 5-hydroxy-1-[(1,3-dihydroxy-2-propoxy)methyl]uracil (11), 6-methyl-1-[(1,3-dihydroxy-2-propoxy)-methyl]uracil (12), and its 3-fluoro-derivative (13).Key words: fluorinated nucleoside analogues, gene therapy, PET, thymidine kinase.
Azo-functionalized dendrimers
Authors: Cheon Kap-Soo , Kazmaier Peter M , Keum Sam-Rok , Park Kuk-Tae , Buncel Erwin
Published: April 2004

We report the synthesis of azo-functionalized Starburst polyamidoamine (PAMAM) dendrimers. The following three systems of azo-functionalized PAMAM dendrimers were prepared by different synthetic routes: (i) phenylazo derivatives; (ii) naphthalimide azo derivatives; and (iii) phthalimide azo derivatives. Model compounds in each system were synthesized for spectroscopic comparison. Confirmation of structure was achieved using a combination of NMR and IR spectroscopy to ascertain the functional sites (i.e., the azo and the cyclic imides), while mass spectrometry and UVvis spectrophotometry were employed to ascertain the extent of functionalization. Substitution by the azo pendent groups increased the thermal stability of PAMAM dendrimers (TGA weight loss of the naphthalimide azo-functionalized PAMAM dendrimers up to 300 °C, ca. 5%).Key words: dendrimers, azo compounds, hydrazones, tautomerism, hydrogen bonding.
Is coarse woody debris a net sink or source of nitrogen in the red spruce  Fraser fir forest of the southern Appalachians, U.S.A.?
Authors: Creed I F , Morrison D L , Nicholas N S
Published: April 2004

The red spruce (Picea rubens Sarg.)  Fraser fir (Abies fraseri (Pursh) Poir.) forest of the southern Appalachians contains a significant amount of coarse woody debris (CWD) that may affect the nitrogen (N) export signal in streams originating from this N-saturated system. Interpretation of the N sink versus source status of CWD of red spruce and Fraser fir was dependent on the method used. Over a chronosequence of decay, (1) N concentrations suggested a N sink (i.e., a net gain of N of 923% in red spruce and 563% in Fraser fir relative to N in live trees); (2) N contents that reflected changes in density suggested a smaller N sink (i.e., a net gain of N of 218% in red spruce and 125% in Fraser fir relative to N in live trees), but the stoichiometry of N and C suggested a N source in early stages of decay and a N source in the most advanced stage of decay only; and (3) N contents that reflected changes in volume suggested a N source (i.e., a net N loss of 172% in red spruce and 122% in Fraser fir). The C/N ratios in CWD suggested that the shift from a N source to a N sink represented a shift from the mobilization of dissolved organic N to the immobilization of ammonium N and (or) nitrate N. The magnitude of the net change in N contents in both red spruce and Fraser fir was amongst the highest reported in literature, suggesting that CWD plays a particularly important role in N dynamics in N saturated forests.
The effects of spatial aggregation of complex topography on hydroecological process simulations within a rugged forest landscape: development and application of a satellite-based topoclimatic model
Authors: Kang S , Lee D , Kimball J S
Published: April 2004

We evaluated the effects of topographic complexity on landscape carbon and hydrologic process simulations within a rugged mixed hardwood forest by developing and applying a satellite-based hydroecological model at multiple spatial scales. The effects of topographic variability were evaluated by aggregating raster-based digital elevation model and satellite-derived leaf area index inputs across eight different spatial resolutions from 30 m (62 208 pixels) to 2160 m (12 pixels). Our modeling analysis showed that the effect of topography was the strongest on solar radiation and temperature, intermediate on soil water and evapotranspiration, and ambiguous on soil respiration. Spatial aggregation of model inputs smoothed heterogeneous spatial patterns of modeled output variables relative to fine-scale results. Model outputs varied nonlinearly with different levels of spatial aggregation, while spatial variability of model inputs and outputs were dampened at increasingly coarse aggregation levels. Biases in spatially aggregated model predictions were generally less than ±10%, except for solar radiation, which showed biases of up to +50% at coarser spatial scales. The large positive bias in the solar radiation implies that overestimation of biophysical variables that are sensitive to solar radiation (e.g., photosynthesis and net primary production) may be considerable in rugged forested landscapes unless subgrid scale effects are accounted for.
The effects of gaps and liming on forest floor decomposition and soil C and N dynamics in aFagus sylvaticaforest
Authors: Bauhus J , Vor T , Bartsch N , Cowling A
Published: April 2004

Despite the importance of gaps in the dynamics and management of many forest types, very little is known about the medium- to long-term soil C and N dynamics associated with this disturbance. This study was designed to test the hypothesis that gap creation and lime application, a routine measure in many European forests to ameliorate soil acidity, lead to accelerated litter decomposition and thus a reduction in the forest floor and soil C and N pools. Four gaps were created in 1989 in a mature European beech (Fagus sylvatica L.) forest on acid soil with a moder humus, and lime (3 t dolomite·ha1) was applied to two of these and surrounding areas. Litter and fine-root decomposition was measured in 19921993 and 19961998 using litterbags. Forest floor (L, F, and H layers) and mineral soil (040 cm) C and N pools were determined in 1989 and 1997. Eight years following silvicultural treatments, there was no change in C and N over the entire forest soil profile including forest floor. Reductions in the F and H layers in limed gaps were compensated for by increases in soil C and N in the surface (010 cm) mineral soil. Decomposition of F litter was significantly accelerated in limed gaps, leading to the development of a mullmoder, whereas gap creation alone had no effect on mass loss of F material in litterbags. Gap size disturbances in this acid beech forest appear to have minimal influences on soil C and N stocks. However, when combined with liming, changes in the humus form and vertical distribution of soil C and N may occur.
Predicting crown class in three western conifer species
Authors: Nigh Gordon D , Love Bobby A
Published: April 2004

Assessing the crown class (dominant, codominant, intermediate, suppressed) of a tree is a subjective procedure. Most definitions of crown class are based on the relative height of a tree and (or) the amount of light that is incident on the tree crown. With this research, we devised a classification scheme, based on easily measured tree variables, to assign a crown class to trees. Our data consisted of tree measurements, including crown class, from four stem-mapped 0.05-ha sample plots with buffers. The light model tRAYci was used to assess the light incident on each tree crown. These data gave us field-based and light-based assessments of crown class. The classification and regression tree technique  with diameter at breast height (DBH), height, relative DBH, relative height, height to the crown base, and crown depth as variables  was used to classify the trees. Accuracy rates of 91% and 82% were achieved for the field-based and light-based assessments of crown class, respectively.
Temperature-dependent rate models of vascular cambium cell mortality
Authors: Dickinson Matthew B , Johnson Edward A
Published: April 2004

We use two rate-process models to describe cell mortality at elevated temperatures as a means of understanding vascular cambium cell death during surface fires. In the models, cell death is caused by irreversible damage to cellular molecules that occurs at rates that increase exponentially with temperature. The models differ in whether cells show cumulative effects of heating. The temperature dependencies of the models' rate parameters were estimated from cell-count data after exposing live-bark tissues from four Canadian Rocky Mountain tree species to a range of fixed temperatures in a water bath. Based on both models, lodgepole pine's (Pinus contorta Dougl. ex Loud.) growing season vascular cambium cells experienced lower mortality rates at elevated temperatures than those of aspen (Populus tremuloides Michx.), Engelmann spruce (Picea engelmannii Parry ex Engelm.), and Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco). Growing and dormant season differences were marginal. With reservations for lodgepole pine, both models predicted cell survival after exposures to rising and falling temperatures such as would be experienced by live tissues during fires. A simulation involving conduction heat transfer from flames and vascular cambium cell mortality suggests that differences among species in thermal tolerance are small compared with the effects of bark thickness. Although stem vascular cambium cell mortality was complete when tissues reached 60 °C during simulated surface fires, it may not be warranted to apply the 60 °C threshold to other tissues exposed to contrasting temperature regimes during fires.
Multivariate patterns of adaptive genetic variation and seed source transfer in Picea mariana
Authors: Beaulieu Jean , Perron Martin , Bousquet Jean
Published: April 2004

A short-term retrospective test trial was carried out using 90 open-pollinated families representing 30 provenances of black spruce (Picea mariana (Mill.) BSP) from Quebec. Seedlings were transplanted on three sites along a latitudinal gradient, and eleven growth and phenological traits were measured during the second and the third growing seasons. Analyses of variance indicated for most of the traits significant differences among provenances and families-within-provenances. Principal component analysis was used to summarize the variation observed among provenances into two principal components, which accounted for 79% of the total variation for all traits. Regression models developed to relate each trait and the principal component scores to geoclimatic variables explained between 55% and 86% of the variation observed among provenances. Variation in growth traits and phenological traits appeared to be related to geoclimatic factors. The models were validated using data from a range-wide provenance test, and relative risks associated with seed source transfer were estimated. The R2 values between the transfer risk and the provenance heights ranged from 0.02 to 0.58, whereas they were slightly lower for diameters. On average, the relative risks varied from 36% to 67%. Individual provenance values ranged from 4% to 94%. A geographic information system tool was designed to assist the forest managers in making seed transfer decisions.
Assessing forest metrics with a ground-based scanning lidar
Authors: Hopkinson Chris , Chasmer Laura , Young-Pow Colin , Treitz Paul
Published: April 2004

A ground-based scanning lidar (light detection and ranging) system was evaluated to assess its potential utility for tree-level forest mensuration data extraction. Ground-based-lidar and field-mensuration data were collected for two forest plots: one located within a red pine (Pinus resinosa Ait.) plantation and another in a mixed deciduous stand dominated by sugar maple (Acer saccharum Marsh.). Five lidar point cloud scans were collected from different vantage points for each plot over a 6-h period on 5 July 2002 using an Optech Inc. ILRIS-3D laser imager. Field- validation data were collected manually over several days during the same time period. Parameters that were measured in the field or derived from manual field measures included (i) stem location, (ii) tree height, (iii) stem diameter at breast height (DBH), (iv) stem density, and (v) timber volume. These measures were then compared with those derived from the ILRIS-3D data (i.e., the lidar point cloud data). It was found that all parameters could be measured or derived from the data collected by the ground-based lidar system. There was a slight systematic underestimation of mean tree height resulting from canopy shadow effects and suboptimal scan sampling distribution. Timber volume estimates for both plots were within 7% of manually derived estimates. Tree height and DBH parameters have the potential for objective measurement or derivation with little manual intervention. However, locating and counting trees within the lidar point cloud, particularly in the multitiered deciduous plot, required the assistance of field-validation data and some subjective interpretation. Overall, ground-based lidar demonstrates promise for objective and consistent forest metric assessment, but work is needed to refine and develop automatic feature identification and data extraction techniques.
Cryopreservation of Pinus radiata zygotic embryo cotyledons: effect of storage duration on adventitious shoot formation and plant growth after 2 years in the field
Authors: Hargreaves Cathy , Grace Lynette , Maas Susan van der , Reeves Cathie , Holden Grant , Menzies Mike , Kumar Satish , Foggo Martin
Published: April 2004

This work is the first report of the cryopreservation of conifer cotyledons without cryoprotectants and their subsequent shoot regeneration and successful establishment of a field trial. Multiple genotypes of radiata pine (Pinus radiata D. Don) embryo cotyledons were stored in liquid nitrogen following a desiccation treatment. Cotyledons that had been stored in liquid nitrogen for 7, 14, and 28 days were compared with noncryopreserved cotyledons for adventitious shoot production, root formation on the shoots, and plant growth after 2 years in the field. Of the 72 genotypes tested, 79%87% of them produced shoots on at least one treatment and 59% of them produced shoots on all treatments. Rooting rates of shoots were not affected by treatment, with the cryopreserved treatments rooting as well as the noncryopreserved controls. Height growth of plants in the nursery was similar across all treatments after 2 years but was influenced by setting date. The higher genotype capture possible with adventitious methodologies, compared with that of somatic embryogenesis, and the preservation of juvenile characteristics while material is stored in liquid nitrogen make adventitious methods worthy of intensive study for possible commercial application.
An evaluation of diagnostic tests and their roles in validating forest biometric models
Authors: Yang Yuqing , Monserud Robert A , Huang Shongming
Published: April 2004

Model validation is an important part of model development. It is performed to increase the credibility and gain sufficient confidence about a model. This paper evaluated the usefulness of 10 statistical tests, five parametric and five nonparametric, in validating forest biometric models. The five parametric tests are the paired t test, the Χ2 test, the separate t test, the simultaneous F test, and the novel test. The five nonparametric tests are the Brown-Mood test, the KolmogorovSmirnov test, the modified KolmogorovSmirnov test, the sign test, and the Wilcoxon signed-rank test. Nine benchmark data sets were selected to evaluate the behavior of these tests in model validation; three were collected from Alberta and six were published elsewhere. It was shown that the usefulness of statistical tests in model validation is very limited. None of the tests seems to be generic enough to work well across a wide range of models and data. Each model passed one or more tests, but not all of them. Because of this, caution should be exercised when choosing a statistical test or several tests together to try to validate a model. It is important to reduce and remove any potential personal bias in selecting a favorite test, which can influence the outcome of the results.
Comparing direct and indirect methods of assessing canopy structure in a northern hardwood forest
Authors: Rhoads Anne G , Hamburg Steven P , Fahey Timothy J , Siccama Thomas G , Kobe Richard
Published: April 2004

Several methods exist for measuring forest canopies following disturbance, and the biases and differences among them are unclear. We compared techniques for measuring the northern hardwood forest's canopy structure at the Hubbard Brook Experimental Forest, New Hampshire, following the severe ice storm of January 510, 1998. Methods included leaf area index (LAI) using LI-COR's LAI-2000, visual damage assessments based on tree branch loss, radiation estimates from hemispherical photographs, and LAI determined from litterfall. LAI-2000 measurements were not significantly related to visual damage class estimates, but were strongly correlated with radiation estimates from hemispherical photographs and average LAI values from litterfall. LAI from the LAI-2000 and litterfall differed on a point-by-point basis, but were similar at the stand scale. The LAI-2000 has the highest precision for large-scale measurements. Visual damage estimates appear adequate for assessing large-scale patterns of disturbance intensity in the northern hardwood forest, but the LAI-2000 is more accurate at quantifying canopy structure at large plot or stand scales. Hemispherical photographs may also accomplish this, but are better suited to characterizing the distribution of canopy gaps and light availability patterns over time. Litterfall provides accurate and precise measurements of small-scale LAI patterns in deciduous forests and reveals species-specific patterns.
Effects of stand tending on the estimation of aboveground biomass of planted juvenile white spruce
Authors: Pitt Douglas G , Bell F Wayne
Published: April 2004

Stem, branch, needle, and total aboveground biomass were assessed for three 9- to 12-year-old white spruce (Picea glauca (Moench) Voss) plantations, each subjected to three different stand tending options at age 4 to 7. Biomass components were predicted from measures of stem diameter with coefficients of variation between 24% and 29%. Diameter at breast height (DBH) generally provided lower prediction precision than did the lower stem measures tested (coefficient of variation > 35%). The addition of tree height in models reduced the standard error of the estimates for stem and total biomass by an average of 48% and 8%, respectively, and compensated for different height/diameter ratios imposed on the spruce by the stand tending treatments. Needle and branch biomass models were invariant to the tending treatments and, consequently, to the addition of height as an independent variable. Predictions from existing published white spruce equations suggest that extrapolation to this study area would have led to adequate stem biomass estimation but to serious (>55%) underestimates of branch, needle, and, correspondingly, total biomass. Slow self-pruning by plantation spruce, particularly before crown closure, is cited as a possible reason for these differences.
Productivity of Ontario initial-attack fire crews: results of an expert-judgement elicitation study
Authors: Hirsch Kelvin G , Podur Justin J , Janser Robert F , McAlpine Robert S , Martell David L
Published: April 2004

A structured expert-judgement elicitation technique was used to develop probability distributions for fireline production rates for Ontario's three- and four-person initial-attack crews for seven common fuel types and two distinct levels of fire intensity (i.e., low, 500 kW/m; moderate, 1500 kW/m). A total of 141 crew leaders provided 900 estimates of the minimum, maximum, and most likely (mode) time to construct 610 m (2000 ft) of fireline. This information was used to estimate parameters for beta probability distributions for each individual and scenario. Analysis of variance (ANOVA) of the beta-distribution parameters (α and β) and the three time estimates indicated that fuel type, intensity, crew size, and crew-leader experience all have a statistically significant (p < 0.05) influence on estimated crew productivity. The 28 scenario-specific and 7 aggregated distributions and expected values can be used in many operational fire-management activities (e.g., presuppression planning, initial-attack dispatching, initial-fire assessments) and incorporated into initial-attack containment models. These results also provide baseline data on crew productivity that can be used in larger strategic analyses to gauge the benefits of new fire-suppression equipment and techniques for the entire fire-management program.
Effects of different sources and rates of sulphur on the growth and foliar nutrition of nitrogen-fertilized lodgepole pine
Authors: Brockley R P
Published: April 2004

The effects of nitrogen (N) fertilizer, alone and in combination with different sources and rates of sulphur (S), on foliar nutrients and tree growth are reported over 3 and 6 years, respectively. After 3 years, foliar S levels in the N+S treatments were significantly higher than those in N-only treatments at all six study locations. Temporal patterns of foliar S response varied significantly with S source. When applied as ammonium sulphate (AS), foliar levels increased sharply in year 1 and slowly declined over the next 2 years. Conversely, additions of elemental S (S0), in the form of S0  sodium bentonite fertilizer, usually did not increase foliar S concentration in year 1, but had increasingly positive effects on foliar S in years 2 and 3. An increase in the S application rate from 50 to 100 kg/ha resulted in only a modest improvement in foliar S concentration for both S sources. Differences in individual-tree basal area increment between N and N+S treatments were statistically significant in only two of six trials. Prefertilization levels of foliar N and sulphate S, and probable induced deficiencies of nonadded nutrients following N fertilization, largely explained basal area and height responses to N and N+S additions at the six study sites. Despite delayed oxidation, S0 was as effective as the more readily available AS in stimulating radial growth after 6 years. However, the relative effectiveness of S source varied with S application rate in two trials. In both cases, basal area increment was positively related to application rate when S was applied as AS. Conversely, the effect of application rate was distinctly negative when S0 was applied. Despite large differences in short-term availability of AS and S0, the results from this study support the conclusion that the two S sources are likely equally effective in alleviating S deficiencies and in promoting tree growth of S-deficient lodgepole pine (Pinus contorta Dougl. var. latifolia Engelm.).
Aboveground interactions and productivity in mixed-species plantations of Acacia mearnsii and Eucalyptus globulus
Authors: Bauhus Jürgen , van Winden Aaron P , Nicotra Adrienne B
Published: April 2004

This study compared productivity in mixed-species plantations of Eucalyptus globulus ssp. pseudoglobulus (Naudin ex Maiden) Kirkpatr. and Acacia mearnsii de Wild with pure stands of each species and investigated how this might be explained by canopy stratification between species and changes in leaf characteristics of eucalypts. Investigations were carried out at a trial using the replacement series design, which consisted of the following combinations: 100% eucalypts (100%E), 75% eucalypts + 25% acacia (75%E:25%A), 50% eucalypts + 50% acacia (50%E:50%A), 25% eucalypts + 75% acacia (25%E:75%A), and 100% acacia (100%A). At 9.5 years, stem volume and biomass were highest in 50%E:50%A treatments. Canopy stratification occurred in all mixtures, with acacias in the lower and eucalypts in the upper canopy stratum. This and the increasing canopy light interception with increasing proportion of acacia in the mixture indicated that A. mearnsii is substantially more shade tolerant than E. globulus. Midcanopy foliage of E. globulus in the 50%E:50%A mixture had higher foliage nitrogen (N) but lower phosphorus (P) concentrations and lower light-saturated net photosynthesis rates (Amax) than those in the 100%E treatment. In addition, similar relationships between eucalypt crown volume and stem biomass across treatments indicated that eucalypt crowns were not more efficient in mixture. Our study indicates that the productivity gains in these mixtures may be partially attributable to aboveground niche separation between species.
INCORPORATING CONCEPTS OF BUSINESS PRIORITY INTO QUALITY FUNCTION DEPLOYMENT
Authors: TAN KAY CHUAN , RAGHAVAN VIJAYALAKSHMI
Published: April 2004

While QFD has established itself as an important tool that relates the voice of the customer to a product's technical requirements, much remains unresolved in terms of coordination among the multi-department QFD team members. In implementing the technical requirements, conflicting resource constraints between departments translate into business risk. This paper presents two concepts — circle-of-control (COC) and effort-impact matrix (EI) — to help bridge the gap between the technical importance ranking and the business perspective attached to the technical requirements. COC is the concept of feasibility analysis with respect to implementing the requirements. EI is the concept of identifying an organisation's efficiency in implementing the requirements.
EXPLORING PROCESSES OF RESOURCE EXCHANGE AND CO-CREATION IN STRATEGIC PARTNERING FOR NEW PRODUCT DEVELOPMENT
Authors: PERKS HELEN
Published: April 2004

This study articulates and explains the process of resource evolution in long-term new product development collaboration between competing large firms. By adopting a resource-based view of collaboration, the study maps, at a micro level, the evolution of R&D skills within an Italian manufacturer (Olivetti), co-developing mid-range photocopiers with a Japanese manufacturer (Canon), throughout four periods of time (from 1985 to 1998). The study identifies and explores activities leading to resource changes in each period and unravels the underlying explanatory processes behind such behaviour and outcomes. Findings from the study indicate that value in long-term co-development derives from the enduring exchange processes developed throughout the collaboration. The results suggest that investment in processes and mechanisms to adapt and evaluate resources, over time, acts as a critical precursor to effective resource exchange and value creation.
Effects of cytochrome c on the mitochondrial apoptosis-induced channel MAC
Authors: Guo Liang , Pietkiewicz Dawn , Pavlov Evgeny V. , Grigoriev Sergey M. , Kasianowicz John J. , Dejean Laurent M. , Korsmeyer Stanley J. , Antonsson Bruno , Kinnally Kathleen W.
Published: April 2004

Recent studies indicate that cytochrome c is released early in apoptosis without loss of integrity of the mitochondrial outer membrane in some cell types. The high-conductance mitochondrial apoptosis-induced channel (MAC) forms in the outer membrane early in apoptosis of FL5.12 cells. Physiological (micromolar) levels of cytochrome c alter MAC activity, and these effects are referred to as types 1 and 2. Type 1 effects are consistent with a partitioning of cytochrome c into the pore of MAC and include a modest decrease in conductance that is dose and voltage dependent, reversible, and has an increase in noise. Type 2 effects may correspond to “plugging” of the pore or destabilization of the open state. Type 2 effects are a dose-dependent, voltage-independent, and irreversible decrease in conductance. MAC is a heterogeneous channel with variable conductance. Cytochrome c affects MAC in a pore size-dependent manner, with maximal effects of cytochrome c on MAC with conductance of 1.9–5.4 nS. The effects of cytochrome c, RNase A, and high salt on MAC indicate that size, rather than charge, is crucial. The effects of dextran molecules of various sizes indicate that the pore diameter of MAC is slightly larger than that of 17-kDa dextran, which should be sufficient to allow the passage of 12-kDa cytochrome c. These findings are consistent with the notion that MAC is the pore through which cytochrome c is released from mitochondria during apoptosis.
The COOH-terminal tail of the GAT-2 GABA transporter contains a novel motif that plays a role in basolateral targeting
Authors: Brown Andrea , Muth Theodore , Caplan Michael
Published: April 2004

The ability of polarized epithelia to perform vectorial transport depends on the asymmetrical distribution of transmembrane proteins among their plasma membrane domains. The establishment and maintenance of these polar distributions relies on molecular signals embedded in the proteins themselves and the interpretation of these signals by cellular sorting machinery. Using Madin-Darby canine kidney (MDCK) cells as an in vitro model of polarized epithelia, our laboratory has previously shown that the COOH-terminal cytoplasmic 22 amino acids of the GAT-2 isoform of the γ-amino butyric acid (GABA) transporter are necessary for its basolateral distribution. We demonstrate that the COOH-terminal tail of the transporter can function as an autonomous basolateral distribution signal, independently of the rest of the transporter. We find that the three-amino acid PDZ domain-interacting motif at the COOH-terminus of GAT-2 is not necessary for its basolateral distribution. Instead, the more proximal seven amino acids are necessary both for targeting and for steady-state distribution. Because this sequence resembles no other known basolateral sorting information, we conclude that these seven amino acids contain a novel basolateral targeting and distribution motif.
Subcellular targeting and function of osteoblast nucleotide pyrophosphatase phosphodiesterase 1
Authors: Vaingankar Sucheta M. , Fitzpatrick Thomas A. , Johnson Kristen , Goding James W. , Maurice Michele , Terkeltaub Robert
Published: April 2004

The ectonucleoside pyrophosphatase phosphodiesterase 1 (NPP1/PC-1) is a member of the NPP enzyme family that is critical in regulating mineralization. In certain mineralizing sites of bone and cartilage, membrane-limited vesicles [matrix vesicles (MVs)] provide a sheltered internal environment for nucleation of calcium-containing crystals, including hydroxyapatite. MV formation occurs by budding of vesicles from the plasma membrane of mineralizing cells. The MVs are enriched in proteins that promote mineralization. Paradoxically, NPP1, the type II transmembrane protein that generates the potent hydroxyapatite crystal growth inhibitor inorganic pyrophosphate (PPi), is also enriched in MVs. Although osteoblasts express NPP1, NPP2, and NPP3, only NPP1 is enriched in MVs. Therefore, this study uses mineralizing human osteoblastic SaOS-2 cells, a panel of NPP1 mutants, and NPP1 chimeras with NPP3, which does not concentrate in MVs, to investigate how NPP1 preferentially targets to MVs. We demonstrated that a cytosolic dileucine motif (amino acids 49–50) was critical in localizing NPP1 to regions of the plasma membrane that budded off into MVs. Moreover, transposition of the NPP1 cytoplasmic dileucine motif and flanking region (AAASLLAP) to NPP3 conferred to NPP3 the ability to target to the plasma membrane and, subsequently, concentrate in MVs. Functionally, the cytosolic tail dileucine motif NPP1 mutants lost the ability to support MV PPi concentrations and to suppress calcification. The results identify a specific targeting motif in the NPP1 cytosolic tail that delivers PPi-generating NPP activity to osteoblast MVs for control of calcification.
Diarrhea-associated HIV-1 APIs potentiate muscarinic activation of Cl- secretion by T84 cells via prolongation of cytosolic Ca2+ signaling
Authors: Rufo Paul A. , Lin Patricia W. , Andrade Adriana , Jiang Lianwei , Rameh Lucia , Flexner Charles , Alper Seth L. , Lencer Wayne I.
Published: April 2004

Aspartyl protease inhibitors (APIs) effectively extend the length and quality of life in human immunodeficiency virus (HIV)-infected patients, but dose-limiting side effects such as lipodystrophy, insulin resistance, and diarrhea have limited their clinical utility. Here, we show that the API nelfinavir induces a secretory form of diarrhea in HIV-infected patients. In vitro studies demonstrate that nelfinavir potentiates muscarinic stimulation of Cl- secretion by T84 human intestinal cell monolayers through amplification and prolongation of an apical membrane Ca2+-dependent Cl- conductance. This stimulated ion secretion is associated with increased magnitude and duration of muscarinically induced intracellular Ca2+ transients via activation of a long-lived, store-operated Ca2+ entry pathway. The enhanced intracellular Ca2+ signal is associated with uncoupling of the Cl- conductance from downregulatory intracellular mediators generated normally by muscarinic activation. These data show that APIs modulate Ca2+ signaling in secretory epithelial cells and identify a novel target for treatment of clinically important API side effects.
Protection against hypoxia-induced blood-brain barrier disruption: changes in intracellular calcium
Authors: Brown Rachel C. , Mark Karen S. , Egleton Richard D. , Davis Thomas P.
Published: April 2004

Tissue damage after stroke is partly due to disruption of the blood-brain barrier (BBB). Little is known about the role of calcium in modulating BBB disruption. We investigated the effect of hypoxic and aglycemic stress on BBB function and intracellular calcium levels. Bovine brain microvessel endothelial cells were treated with A-23187 to increase intracellular calcium without hypoxia or treated with a calcium chelator (BAPTA) or calcium channel blockers (nifedipine or SKF-96365) and 6 h of hypoxia. A-23187 alone did not increase paracellular permeability. Hypoxia increased intracellular calcium, and hypoxia or hypoxia-aglycemia increased paracellular permeability. Treatment with nifedipine and SKF-96365 increased intracellular calcium under normoglycemic conditions, instead of blocking calcium influx, and was protective against hypoxia-induced BBB disruption under normoglycemia. Protection by nifedipine and SKF-96365 was not due to antioxidant properties of these compounds. These data indicate that increased intracellular calcium alone is not enough to disrupt the BBB. However, increased intracellular calcium after drug treatment and hypoxia suggests a potential mechanism for these drugs in BBB protection; nifedipine and SKF-96365 plus hypoxic stress may trigger calcium-mediated signaling cascades, altering BBB integrity.
Spontaneous mitochondrial depolarizations are independent of SR Ca2+ release
Authors: O'Reilly Catherine M. , Fogarty Kevin E. , Drummond Robert M. , Tuft Richard A. , Walsh John V.
Published: April 2004

The mitochondrial membrane potential (ΔΨm) underlies many mitochondrial functions, including Ca2+ influx into the mitochondria, which allows them to serve as buffers of intracellular Ca2+. Spontaneous depolarizations of ΔΨm, flickers, have been observed in isolated mitochondria and intact cells using the fluorescent cationic lipophile tetramethylrhodamine ethyl ester (TMRE), which distributes across the inner mitochondrial membrane in accordance with the Nernst equation. Flickers in cardiomyocytes have been attributed to uptake of Ca2+ released from the sarcoplasmic reticulum (SR) via ryanodine receptors in focal transients called Ca2+ sparks. We have shown previously that an increase in global Ca2+ in smooth muscle cells causes an increase in mitochondrial Ca2+ and depolarization of ΔΨm. Here we sought to determine whether flickers in smooth muscle cells are caused by uptake of Ca2+ released focally in Ca2+ sparks. High-speed three-dimensional imaging was used to monitor ΔΨm in freshly dissociated myocytes from toad stomach that were simultaneously voltage clamped at 0 mV to ensure the cytosolic TMRE concentration was constant and equal to the low level in the bath (2.5 nM). This approach allows quantitative analysis of flickers as we have previously demonstrated. Depletion of SR Ca2+ not only failed to eliminate flickers but rather increased their magnitude and frequency somewhat. Flickers were not altered in magnitude or frequency by ryanodine or xestospongin C, inhibitors of intracellular Ca2+ release, or by cyclosporin A, an inhibitor of the permeability transition pore. Focal Ca2+ release from the SR does not cause flickers in the cells employed here.
Calcium-regulated changes in mitochondrial phenotype in skeletal muscle cells
Authors: Freyssenet Damien , Irrcher Isabella , Connor Michael K. , Di Carlo Martino , Hood David A.
Published: April 2004

Cytochrome c expression and mitochondrial biogenesis can be invoked by elevated intracellular Ca2+ in muscle cells. To characterize the potential role of Ca2+ as a messenger involved in mitochondrial biogenesis in muscle, we determined the effects of the Ca2+ ionophore A-23187 on the expression of nuclear- and mitochondrially encoded genes. Treatment of myotubes with 1 μM A-23187 for 48–96 h increased nuclear-encoded β-subunit F1ATPase and malate dehydrogenase (MDH) mRNA levels by 50–100% ( P < 0.05) but decreased mRNA levels of glutamate dehydrogenase (GDH) by 19% ( P < 0.05). mRNA levels of the cytochrome c oxidase (COX) nuclear-encoded subunits IV, Vb, and VIc were unchanged, whereas the mitochondrially encoded subunits COX II and COX III were decreased by 30 and 70%, respectively ( P < 0.05). This was paralleled by a 20% decrease ( P < 0.05) in COX activity. These data suggest that cytoplasmic Ca2+ differentially regulates the mRNA level of nuclear and mitochondrial genes. The decline in COX II and III mRNA may be mediated by Tfam, because A-23187 modestly reduced Tfam levels by 48 h. A-23187 induced time-dependent increases in Egr-1 mRNA, along with the activation of ERK1/2 and AMP-activated protein kinase. MEK inhibition with PD-98059 attenuated the increase in Egr-1 mRNA. A-23187 also increased Egr-1, serum response factor, and Sp1 protein expression, transcription factors implicated in mitochondrial biogenesis. Egr-1 overexpression increased nuclear-encoded cytochrome c transcriptional activation by 1.5-fold ( P < 0.05) and reduced GDH mRNA by 37% ( P < 0.05) but had no effect on MDH or β-subunit F1ATPase mRNA. These results indicate that changes in intracellular Ca2+ can modify mitochondrial phenotype, in part via the involvement of Egr-1.
Distinctive G protein-dependent signaling in smooth muscle by sphingosine 1-phosphate receptors S1P1 and S1P2
Authors: Zhou Huiping , Murthy Karnam S.
Published: April 2004

We examined expression of sphingosine 1-phosphate (S1P) receptors and sphingosine kinase (SPK) in gastric smooth muscle cells and characterized signaling pathways mediating S1P-induced 20-kDa myosin light chain (MLC20) phosphorylation and contraction. RT-PCR demonstrated expression of SPK1 and SPK2 and S1P1 and S1P2 receptors. S1P activated Gq, G13, and all Gi isoforms and stimulated PLC-β1, PLC-β3, and Rho kinase activities. PLC-β activity was partially inhibited by pertussis toxin (PTX), Gβ or Gαq antibody, PLC-β1 or PLC-β3 antibody, and by expression of Gαq or Gαi minigene, and was abolished by a combination of antibodies or minigenes. S1P-stimulated Rho kinase activity was partially inhibited by expression of Gα13 or Gαq minigene and abolished by expression of both. S1P stimulated Ca2+ release that was inhibited by U-73122 and heparin and induced concentration-dependent contraction of smooth muscle cells (EC50 1 nM). Initial contraction and MLC20 phosphorylation were abolished by U-73122 and MLC kinase (MLCK) inhibitor ML-9. Initial contraction was also partially inhibited by PTX and Gαq or Gβ antibody and abolished by a combination of both antibodies. In contrast, sustained contraction and MLC20 phosphorylation were partially inhibited by a PKC or Rho kinase inhibitor (bisindolylmaleimide and Y-27632) and abolished by a combination of both inhibitors but not affected by U-73122 or ML-9. These results indicate that S1P induces 1) initial contraction mediated by S1P2 and S1P1 involving concurrent activation of PLC-β1 and PLC-β3 via Gαq and Gβγi, respectively, resulting in inositol 1,4,5-trisphosphate-dependent Ca2+ release and MLCK-mediated MLC20 phosphorylation, and 2) sustained contraction exclusively mediated by S1P2 involving activation of RhoA via Gαq and Gα13, resulting in Rho kinase- and PKC-dependent MLC20 phosphorylation.
Role of CC chemokines in skeletal muscle functional restoration after injury
Authors: Warren Gordon L. , O'Farrell Laura , Summan Mukesh , Hulderman Tracy , Mishra Dawn , Luster Michael I. , Kuziel William A. , Simeonova Petia P.
Published: April 2004

The purpose of this study was to determine whether certain chemokines, which are highly expressed in injured skeletal muscle, are involved in the repair and functional recovery of the muscle after traumatic injury. In wild-type control mice, mRNA transcripts of macrophage inflammatory protein (MIP)-1α, MIP-1β, and monocyte chemoattractant protein (MCP)-1 as well as their major receptors, CCR5 and CCR2, increased after freeze injury and gradually returned to control (uninjured) levels by 14 days. Muscle function and histological characteristics were monitored in injured mice that were genetically deficient for the CCR5 receptor (a major receptor for MIP-1α and MIP-1β) and also rendered MCP-1 deficient with neutralizing antibodies. To dissect the role of these chemokines, additional studies were conducted in CCR5- and CCR2-deficient mice. CCR5-/- mice injected with MCP-1 antiserum for the first 3 days after injury exhibited a twofold greater maximal isometric tetanic torque deficit at 14 days after injury than did controls (i.e., 33% vs. 17%; P = 0.002). The impaired functional recovery was accompanied with an increased fat infiltration within the regenerating muscle without a significant difference in the influx of inflammatory cells, including macrophages. Strength recovery was also impaired in mice deficient for the receptor of MCP-1, CCR2, but not in CCR5-/- mice that were not injected with MCP-1 antiserum. The data suggest that MCP-1/CCR2 plays a role in the regeneration and recovery of function after traumatic muscle injury.