bluuebunny/crossref_metadata_2025 huggingface dataset:
Enhancement of low-temperature tolerance in watermelon (Citrullus lanatus) seedlings by cool-hardening germination
Authors: Guo Feng-Xia , Chen Yuan , Li Xin-Rong , Xu Shi-Jian , An Li-Zhe , Liu Dong-Shun
Published: May 2007

To determine and elucidate the role of cool-hardening germination in the subsequent development of low-temperature tolerance in tropical and subtropical plants, 10-day-old watermelon (Citrullus lanatus) seedlings of two hybrids, Jingxin No.1 and Longfengzaochen, germinated at 18 and 30°C, respectively, were removed from growth conditions of 25°C and exposed directly to growth conditions of –2°C for 24 h. The results showed that the seedlings germinated at 18°C, improved the subsequent seedling emergence rate at 25°C and developed tolerance to conditions of –2°C. Low-temperature injury-associated changes of electrolyte leakage and lipid peroxidation in cotyledons and lower radicle vigour, measured as 2,3,5-triphenyltetrazolium chloride reduction, were observed in the seedlings germinated at 30°C but not in those germinated at 18°C, presumably due to the accumulation of soluble proteins. Radicle vigour showed a significantly negative correlation with cotyledon lipid peroxidation. Seed germination at less than the optimal temperature may be a feasible way to improve the cold tolerance of watermelon plants.
Application of composted pig bedding litter on a Vertosol and Sodosol soil. 1. Effect on crop growth and soil water
Authors: Armstrong R. D. , Eagle C. , Matassa V. , Jarwal S. D.
Published: May 2007

Trials were undertaken at two sites with contrasting soil types in the Wimmera region of Victoria: a well-structured grey cracking clay soil (Vertosol) at Traynors Lagoon and a poorly structured sodic clay soil (Sodosol) at Gre Gre. The effect of a once-off application of three different types of bedding litter (wheat straw and two types of rice hulls) applied at three rates (20, 30 and 40 t/ha) was compared with that of a control (no amelioration), nitrogen fertiliser (46 kg N/ha) applied to each crop, or nitrogen plus a once-off application of gypsum (2.5 t/ha). The growth of three subsequent crops and soil water was examined.
Pig bedding litter (rice hulls 1, rice hulls 2 or wheat straw) produced marked improvements in the dry matter production and grain yield of the first crop (wheat) in 1997 and a following canola crop in 1998. In 1999, bedding litter significantly improved the growth of an oats crop at Gre Gre, but had no effect on a crop of field peas at Traynors Lagoon. The beneficial effects of bedding litter on grain yields, however, were matched by small but significant reductions in grain quality resulting from soil water limitations for the yield potential. Although crop growth was improved by the addition of nitrogen fertiliser each year or both nitrogen plus gypsum, the effect was usually small compared with that of adding litter and provided minimal residual value in the following year. There was a general trend for gravimetric soil water to be higher at sowing where bedding litter had been applied, especially at Gre Gre. In contrast, soil water tended to be lower at grain maturity at Traynors Lagoon, where bedding litter or nitrogen fertiliser had been applied, reflecting the enhanced crop growth in these treatments compared with the control. There was no consistent effect of treatments on soil water at maturity in either 1998 or 1999 at Gre Gre.
Impact of heavy metal toxicity on plant growth, symbiosis, seed yield and nitrogen and metal uptake in chickpea
Authors: Wani P. A. , Khan M. S. , Zaidi A.
Published: May 2007

Experiments were conducted to investigate the phytotoxic effects of heavy metals on chickpea, grown in unsterilised soils. Cadmium at 23 mg/kg soil, when used alone or in combination with other metals, was found to be the most toxic and significantly (P ≤ 0.05) reduced the plant growth, nodulation, chlorophyll content, and root and shoot N contents. Cadmium (23 mg/kg soil) and lead (390 mg/kg soil) reduced the number of nodules by 69.2 and 13.7%, respectively. Cadmium at 5.75 and 11.5 mg/kg soil decreased the seed yield by 14 and 19%, respectively, compared with the control. In contrast, lead at 97.5 and 195 mg/kg soil increased the seed yield by 12.3 and 8.8%, respectively, above the control. Generally, the chlorophyll content decreased with increasing rates of each metal. The root and shoot N content decreased by 33.3 and 30.7% at 23 mg/kg of cadmium, whereas lead at 390 mg/kg soil increased the root and shoot N content by 10 and 3%, respectively, above the control. The grain protein decreased gradually with increasing rates of each metal. An average maximum reduction (27%) in grain protein was observed with mixtures of 23 mg cadmium + 135 mg chromium + 580.2 mg nickel per kg soil. Flowering in chickpea plants was delayed following metal application. The degree of toxicity of heavy metals on the measured parameters decreased in the following order: cadmium, zinc, nickel, copper, chromium, then lead. Accumulation of heavy metals was higher in the roots relative to the shoots of chickpea and was significantly correlated with the concentration of the metals added to the soil.
Feed conversion efficiency as a key determinant of dairy herd performance: a review
Authors: Beever D. E. , Doyle P. T.
Published: May 2007

This paper focuses on dairy herd performance in the United Kingdom and southern Australia, where feed costs have been estimated to comprise between 40 and 67% of the total costs of production. The efficiency of conversion of grazed pasture, home grown forages and purchased feeds into milk has a major bearing on farm profit. Feed conversion efficiency (FCE), defined as ‘kg milk of standardised composition with respect to protein and fat concentrations produced per kg feed dry matter consumed’, is a useful measure of the performance of a farm feeding system, but is seldom used by dairy farmers. It could also be defined as ‘g protein plus fat produced per kg feed dry matter consumed’, given that farmers are often paid for these components. The value of estimating FCE on an annual or shorter-term basis is discussed in relation to accepted principles of feed utilisation and dairy cow energy requirements. The implications of feed intake, conversion of ingested nutrients into absorbed nutrients and the subsequent utilisation of these nutrients for milk production or other purposes, as well as the effects of stage of lactation on FCE, are reviewed. Measuring FCE and identifying opportunities for improvement is relatively straightforward in housed feeding systems, but is more problematic under grazing. Hence, approaches and the key assumptions in estimating FCE in grazing situations, as well as possible limitations of these estimates, are discussed. Finally, a case study examining the potential impact of improved nutritional strategies on FCE and on margin over feed costs is presented. It is concluded that, to remain profitable, dairy farmers need to have a sound knowledge of cow nutrition, along with appropriate measures of FCE to monitor the performance of their milk production system. Such indicators of the biological performance of the farming system are most useful when used in conjunction with appropriate measures of economic performance.
Effects of windbreak structure on shelter characteristics
Authors: Bird P. R. , Jackson T. T. , Kearney G. A. , Roache A.
Published: May 2007

Eleven windbreaks (Monterey cypress, Monterey pine, tuart, sugar gum, black wattle and mixed native species) were studied in south-west Victoria. Windrun (U) was measured with cup anemometers set above ground (Z) at 1.5 m and 0.5 m (eight windbreaks), 1.5 m (two windbreaks), or 0.5 and 0.25 m (0.95 m mesh). The U pattern (U/U0, where U0 is open windspeed) was: (1) to windward, a shelter effect to at least –3 H, (where H means windbreak height) with a reduction of 20% or more at –1 H and (2) to lee, Xmin (position of minimum windspeed, Umin) from 1–7 H; Umin (minimum U/Uo) varied with windbreak density; and XS (distance where U/U0 is <0.8) varied from 8–25 H. Optical porosity (βO) was 0.16–0.53 compared with 0.24–0.61 for aerodynamic porosity (βA), obtained from the ratio of Umin and U0. βA from present data and calculated for windbreaks of previous studies, showed a curvilinear effect of windbreak porosity (βA, %) on Xmin, but little effect on XS: Xmin (H) = 3.008LnβA – 6.6 (adjusted r2 = 0.33, P < 0.0001, r.s.d. = 1.8); XS (H) = 12.2+ 0.307βA – 0.0047βA2 (adjusted r2 = 0.07, P < 0.08, r.s.d. = 4.1). Effective shelter is best obtained by establishing tall, dense windbreaks and excluding browsing livestock.
Bodyweight QTL on mouse chromosomes 4 and 11 by selective genotyping: regression v. maximum likelihood
Authors: Benyamin Beben , Martin Ian C. A. , Cheung Carol C. , Buckley Michael F. , Thomson Peter C. , Visscher Peter M. , Moran Chris
Published: May 2007

Two quantitative trait loci (QTL) for mouse bodyweight have previously been reported on mouse chromosomes (MMU) 4 and 11 from crosses of a highly fecund and large mouse strain, Inbred Quackenbush-Swiss 5 (QSi5) and C57Bl/6J. QSi5 has now been crossed with CBA/CaH to produce 1128 F2 mice to confirm the existence and effect of these QTL. In total, 226 mice from the upper and lower deciles for bodyweight were genotyped using 12 microsatellite markers covering MMU4 and MMU11. Regression and maximum likelihood based interval mapping by either including all mice (ungenotyped mice were treated as having missing genotypes) or including only selectively genotyped mice in the analyses were used to estimate the positions and effects of the QTL. The results confirmed the existence and effects of both QTL. Although all methods estimated the same QTL positions, the QTL effects were overestimated compared with the estimates using a suggested method (maximum likelihood by including all mice in the analysis). However, the overestimated QTL effects could be mathematically corrected. Since the confidence intervals of both QTL are still too large for positional cloning, an advanced intercross line is being bred for finely mapping these bodyweight QTL.
Evaluation of garlic extract on bud dormancy release of 'Royal Gala' apple trees
Authors: Botelho R. V. , Müller M. M. L.
Published: May 2007

This study aimed to examine the effects of garlic extract (Bioalho) on bud break of ‘Royal Gala’ apple trees compared with the effects of the conventionally used hydrogen cyanamide (H2CN2). In the southern region of Brazil, immediately after winter pruning on 19 September 2005, the following treatments were sprayed at dormant bud stage using a hand sprayer: (1) control (untreated); (2) 1% garlic extract (GE); (3) 5% GE; (4) 10% GE; (5) 2% mineral oil (MO); (6) 1% GE + 2% MO; (7) 5% GE + 2% MO; (8) 10% GE + 2% MO; (9) 0.4% H2CN2 + 4% MO. GE at 1 or 5% + 2% MO showed similar effects compared with H2CN2 alone, achieving ~80% bud sprouting, whereas 2% MO and the untreated control attained 53 and 18% bud sprouting, respectively. The 10% GE + 2% MO treatment was superior to the others treatments, reaching 95% bud sprouting at 50 days after treatments. The application of 10% GE + 2% MO was also the most effective in advancing bloom. Unfortunately, in this experiment, this also contributed to reduced fruit yield, since the early anthesis coincided with an atypical rainfall in the beginning of spring.
Efficacy of a lasalocid supplement in the diet of dairy cows in early lactation in a pasture-based dairy system
Authors: Stockdale C. R.
Published: May 2007

The lasalocid supplement, Bovatec, was fed to dairy cows at 300 mg of active ingredient for ~3 weeks precalving to up to 16 weeks postcalving in a pasture-based system. Sixty primiparous cows and 120 multiparous cows were allocated to equivalent control and lasalocid groups based on expected calving date, size and previous production history. To facilitate the feeding of the lasalocid, it was mixed with maize silage (~1 kg DM/cow.day) and fed as one feed on a concrete feed pad early in the morning each day before calving and before the afternoon milking during lactation. The control group received the maize silage without lasalocid. Otherwise, the feeding of both groups was exactly the same. The key response associated with adding lasalocid to the diet differed between the primiparous and multiparous cows. Although the average daily milk yield responses to lasalocid were not significant (P > 0.05) at 1.1 and 0.6 kg/cow for the primiparous and multiparous cows, respectively, significant (P < 0.05) increases in the milk yield of the primiparous cows were consistently recorded between weeks 5 and 15 of lactation. With the multiparous cows, there was a significant (P < 0.05) decrease in the circulating concentrations of serum β-hydroxybutyrate in those fed the lasalocid, with this being related to a tendency (P = 0.087) for these animals to maintain higher body condition scores for much of the early lactation treatment period. There were no other treatment differences of biological importance.
Multiple effects of the starch synthase II mutation in developing wheat endosperm
Authors: Kosar-Hashemi Behjat , Li Zhongyi , Larroque Oscar , Regina Ahmed , Yamamori Makoto , Morell Matthew K. , Rahman Sadequr
Published: May 2007

A line of wheat (Triticum aestivum L.), sgp-1, that does not express starch synthase II (SSII, also known as SGP-1) has previously been reported. In this study, F1 derived doubled haploid lines with homozygous wild type or mutant alleles for SGP-1 genes were identified from a cross between the original mutant and a wild type Australian cultivar. Analysis of the starch granules showed that in the mutant lines they are markedly distorted from 15 days postanthesis during grain development. Starch branching patterns showed an increase in the proportion of short chains (DP 6–10) at an earlier stage, but this increase became much more pronounced at 15 days postanthesis and persisted until maturity. There was also a consistent and drastic reduction throughout seed development in the relative amounts of starch branching enzyme II (SBEII, comprising SBEIIa and SBEIIb) and starch synthase I (SSI) bound to the starch granules. In the soluble phase, however, there was relatively little change in the amount of SBEIIb, SBEIIa or SSI protein. Therefore loss of SSII specifically leads to the loss of SBEIIb, SBEIIa and SSI protein in the granule-bound phase and the effect of this mutation is clearly manifest from the mid-stage of endosperm development in wheat.
Decrease in the capacity for RuBP carboxylation and regeneration with the progression of cold-induced photoinhibition during winter in evergreen broadleaf tree species in a temperate forest
Authors: Miyazawa Yoshiyuki , Kikuzawa Kihachiro , Otsuki Kyoichi
Published: May 2007

We measured the photosynthetic capacity (RuBP carboxylation and electron transport capacity at 25°C) and the maximum photochemical efficiency (Fv/Fm) from autumn to spring in saplings of two evergreen broadleaf tree species and examined the negative effects of photoinhibition on the photosynthetic capacity. Saplings were grown in pots under three simulated natural light environments typical of temperate forests: an open site, deciduous understorey and evergreen understorey. During winter, the photosynthetic capacity and Fv/Fm synchronously decreased in leaves in the sun, but not those in the shade. We found large differences in Fv/Fm and photosynthetic capacity, along with a positive correlation between Fv/Fm and the photosynthetic capacity among leaves in different light environments. In photoinhibited leaves that were transferred to the shade in mid-winter, photosynthetic capacity increased synchronously with the increment of Fv/Fm. The decrease in photosynthetic capacity in photoinhibited leaves and the synchronous recovery of photosynthetic capacity with photoinhibition supported the hypothesis that photoinhibition depressed the photosynthetic capacity during winter. We showed that difference in the degree of photoinhibition was responsible for the different winter photosynthetic capacity among leaves exposed to different light environments.
Soil moisture heterogeneity during deficit irrigation alters root-to-shoot signalling of abscisic acid
Authors: Dodd Ian C.
Published: May 2007

The effects of different irrigation techniques on leaf xylem ABA concentration ([X-ABA]leaf) were compared in tomato (Lycopersicon esculentum Mill.). During partial rootzone drying (PRD), water was distributed unevenly to the root system such that part was irrigated while the remainder was allowed to dry the soil. During conventional deficit irrigation (DI), plants received the same volume of water as PRD plants, but water was distributed evenly to the entire root system. When the plant root system was allowed to explore two separate soil compartments, DI plants had a higher [X-ABA]leaf than PRD plants with moderate soil drying, but PRD plants had a higher [X-ABA]leaf than DI plants as the soil dried further. The difference in [X-ABA]leaf between the two sets of plants was not because of differences in either whole pot soil water content (θpot) or leaf water potential (Ψleaf). To investigate the contribution of different parts of the root system to [X-ABA]leaf, individual shoots were grafted onto the root systems of two plants grown in two separate pots, so that the graft union had the appearance of an inverted ‘Y’. After sap collection from detached leaves, removal of the shoot below the graft union allowed sap collection from each root system. Again, DI plants had a higher [X-ABA]leaf than PRD plants when the soil was relatively wet, but the opposite occurred as the soil dried. Root xylem ABA concentration ([X-ABA]root) increased exponentially as soil water content (θ) declined. In DI plants, [X-ABA]root from either pot (or the arithmetic mean of [X-ABA]root) accounted for a similar amount of the variation in [X-ABA]leaf. In PRD plants, [X-ABA]root from the watered side underestimated [X-ABA]leaf, whereas [X-ABA]root from the dry side overestimated [X-ABA]leaf. The arithmetic mean of [X-ABA]root best explained the variation in [X-ABA]leaf, implying continued sap flow from the dry part of the root system (Jdry) at soil water potentials (Ψsoil) at which Jdry had ceased in previous studies of PRD plants (Yao et al. 2001). Evaluating the relationship between Jdry and Ψsoil may assist in maintaining export of ABA (and other growth regulators) from the drying part of the root system, to achieve desirable horticultural outcomes during PRD.
Selenium-induced oxidative stress in coffee cell suspension cultures
Authors: Gomes-Junior Rui A. , Gratão Priscila L. , Gaziola Salete A. , Mazzafera Paulo , Lea Peter J. , Azevedo Ricardo A.
Published: May 2007

Selenium (Se) is an essential element for humans and animals that is required for key antioxidant reactions, but can be toxic at high concentrations. We have investigated the effect of Se in the form of selenite on coffee cell suspension cultures over a 12-day period. The antioxidant defence systems were induced in coffee cells grown in the presence of 0.05 and 0.5 mm sodium selenite (Na2SeO3). Lipid peroxidation and alterations in antioxidant enzymes were the main responses observed, including a severe reduction in ascorbate peroxidase activity, even at 0.05 mm sodium selenite. Ten superoxide dismutase (SOD) isoenzymes were detected and the two major Mn-SOD isoenzymes (bands V and VI) responded more to 0.05 mm selenite. SOD band V exhibited a general decrease in activity after 12 h of treatment with 0.05 mm selenite, whereas band VI exhibited the opposite behavior and increased in activity. An extra isoenzyme of glutathione reductase (GR) was induced in the presence of selenite, which confirmed our previous results obtained with Cd and Ni indicating that this GR isoenzyme may have the potential to be a marker for oxidative stress in coffee.
Short-term interactions between nitrate and iron nutrition in cucumber
Authors: Nikolic Miroslav , Cesco Stefano , Römheld Volker , Varanini Zeno , Pinton Roberto
Published: May 2007

Cucumber (Cucumis sativus L.) plants were precultured for 7 days in either optimal (10 µm) or low (0.5 µm) Fe conditions and then grown for further 5 days in a N-free nutrient solution with (+Fe) or without (–Fe) 10 µm Fe. Thereafter NO3– (4 mm) was added to the nutrient solution for 24 h and, concomitantly, half of the –Fe plants were treated with 1 µm Fe complexed to water extractable humic substances (WEHS). Supply of NO3– to +Fe–N-deprived plants caused a large induction in the capacity to take up the anion by roots, which was accompanied by a rise in root–shoot NO3– concentration. The –Fe plants showed a lower level of induction of NO3– uptake and hence a lower accumulation of the anion in the tissues, these effects being reversed by supply of Fe-WEHS. Supply of either NO3–- or NH4+-N (+/– Fe-WEHS) to –Fe plants promoted the development of the root FeIII-chelate reductase activity, but the capacity of roots to take up the Fe2+ remained unaffected. Results show that an inadequate Fe supply can limit the acquisition of NO3–, whereas NO3– supply can affect Fe uptake by influencing the development and maintenance of a high FeIII-chelate reducing capacity.
Nonlinear relaxation dynamics in elastic networks and design principles of molecular machines
Authors: Togashi Yuichi , Mikhailov Alexander S.
Published: May 2007

Analyzing nonlinear conformational relaxation dynamics in elastic networks corresponding to two classical motor proteins, we find that they respond by well defined internal mechanical motions to various initial deformations and that these motions are robust against external perturbations. We show that this behavior is not characteristic for random elastic networks. However, special network architectures with such properties can be designed by evolutionary optimization methods. Using them, an example of an artificial elastic network, operating as a cyclic machine powered by ligand binding, is constructed.
NRAS mutation causes a human autoimmune lymphoproliferative syndrome
Authors: Oliveira João B. , Bidère Nicolas , Niemela Julie E. , Zheng Lixin , Sakai Keiko , Nix Cynthia P. , Danner Robert L. , Barb Jennifer , Munson Peter J. , Puck Jennifer M. , Dale Janet , Straus Stephen E. , Fleisher Thomas A. , Lenardo Michael J.
Published: May 2007

The p21 RAS subfamily of small GTPases, including KRAS, HRAS, and NRAS, regulates cell proliferation, cytoskeletal organization, and other signaling networks, and is the most frequent target of activating mutations in cancer. Activating germline mutations of KRAS and HRAS cause severe developmental abnormalities leading to Noonan, cardio-facial-cutaneous, and Costello syndrome, but activating germline mutations of NRAS have not been reported. Autoimmune lymphoproliferative syndrome (ALPS) is the most common genetic disease of lymphocyte apoptosis and causes autoimmunity as well as excessive lymphocyte accumulation, particularly of CD4
−
, CD8
−
αβ T cells. Mutations in ALPS typically affect CD95 (Fas/APO-1)-mediated apoptosis, one of the extrinsic death pathways involving TNF receptor superfamily proteins, but certain ALPS individuals have no such mutations. We show here that the salient features of ALPS as well as a predisposition to hematological malignancies can be caused by a heterozygous germline Gly13Asp activating mutation of the
NRAS
oncogene that does not impair CD95-mediated apoptosis. The increase in active, GTP-bound NRAS augments RAF/MEK/ERK signaling, which markedly decreases the proapoptotic protein BIM and attenuates intrinsic, nonreceptor-mediated mitochondrial apoptosis. Thus, germline activating mutations in
NRAS
differ from other p21 Ras oncoproteins by causing selective immune abnormalities without general developmental defects. Our observations on the effects of NRAS activation indicate that RAS-inactivating drugs, such as farnesyltransferase inhibitors should be examined in human autoimmune and lymphocyte homeostasis disorders.
Quantitative Analysis of Membrane Remodeling at the Phagocytic Cup
Authors: Lee Warren L. , Mason David , Schreiber Alan D. , Grinstein Sergio
Published: May 2007

Nascent phagosomes, which are derived from the plasma membrane, acquire microbicidal properties through multiple fusion and fission events collectively known as maturation. Here we show that remodeling of the phagosomal membrane is apparent even before sealing, particularly when large particles are ingested. Fluorescent probes targeted to the plasma membrane are cleared from the region lining the particle before engulfment is completed. Extensive clearance was noted for components of the inner as well as outer monolayer of the plasmalemma. Segregation of lipid microdomains was ruled out as the mechanism underlying membrane remodeling, because markers residing in rafts and those that are excluded were similarly depleted. Selective endocytosis was also ruled out. Instead, several lines of evidence indicate that endomembranes inserted by exocytosis at sites of ingestion displace the original membrane constituents from the base of the phagosomal cup. The Fcγ receptors that trigger phagocytosis remain associated with their ligands. By contrast, Src-family kinases that are the immediate effectors of receptor activation are flushed away from the cup by the incoming membranes. Together with the depletion of phosphoinositides required for signal transduction, the disengagement of receptors from their effectors by bulk membrane remodeling provides a novel means to terminate receptor signaling.
Urokinase Receptor Cleavage: A Crucial Step in Fibroblast-to-Myofibroblast Differentiation
Authors: Bernstein Audrey M. , Twining Sally S. , Warejcka Debra J. , Tall Edward , Masur Sandra K.
Published: May 2007

Fibroblasts migrate into and repopulate connective tissue wounds. At the wound edge, fibroblasts differentiate into myofibroblasts, and they promote wound closure. Regulated fibroblast-to-myofibroblast differentiation is critical for regenerative healing. Previous studies have focused on the role in fibroblasts of urokinase plasmingen activator/urokinase plasmingen activator receptor (uPA/uPAR), an extracellular protease system that promotes matrix remodeling, growth factor activation, and cell migration. Whereas fibroblasts have substantial uPA activity and uPAR expression, we discovered that cultured myofibroblasts eventually lost cell surface uPA/uPAR. This led us to investigate the relevance of uPA/uPAR activity to myofibroblast differentiation. We found that fibroblasts expressed increased amounts of full-length cell surface uPAR (D1D2D3) compared with myofibroblasts, which had reduced expression of D1D2D3 but increased expression of the truncated form of uPAR (D2D3) on their cell surface. Retaining full-length uPAR was found to be essential for regulating myofibroblast differentiation, because 1) protease inhibitors that prevented uPAR cleavage also prevented myofibroblast differentiation, and 2) overexpression of cDNA for a noncleavable form of uPAR inhibited myofibroblast differentiation. These data support a novel hypothesis that maintaining full-length uPAR on the cell surface regulates the fibroblast to myofibroblast transition and that down-regulation of uPAR is necessary for myofibroblast differentiation.
A Developmentally Regulated Chaperone Complex for the Endoplasmic Reticulum of Male Haploid Germ Cells
Authors: van Lith Marcel , Karala Anna-Riikka , Bown Dave , Gatehouse John A. , Ruddock Lloyd W. , Saunders Philippa T.K. , Benham Adam M.
Published: May 2007

Glycoprotein folding is mediated by lectin-like chaperones and protein disulfide isomerases (PDIs) in the endoplasmic reticulum. Calnexin and the PDI homologue ERp57 work together to help fold nascent polypeptides with glycans located toward the N-terminus of a protein, whereas PDI and BiP may engage proteins that lack glycans or have sugars toward the C-terminus. In this study, we show that the PDI homologue PDILT is expressed exclusively in postmeiotic male germ cells, in contrast to the ubiquitous expression of many other PDI family members in the testis. PDILT is induced during puberty and represents the first example of a PDI family member under developmental control. We find that PDILT is not active as an oxido-reductase, but interacts with the model peptide Δ-somatostatin and nonnative bovine pancreatic trypsin inhibitor in vitro, indicative of chaperone activity. In vivo, PDILT forms a tissue-specific chaperone complex with the calnexin homologue calmegin. The identification of a redox-inactive chaperone partnership defines a new system of testis-specific protein folding with implications for male fertility.
Mesenchymal Stem Cells Use Integrin β1 Not CXC Chemokine Receptor 4 for Myocardial Migration and Engraftment
Authors: Ip James E. , Wu Yaojiong , Huang Jing , Zhang Lunan , Pratt Richard E. , Dzau Victor J.
Published: May 2007

Recent evidence has demonstrated the importance of bone marrow-derived mesenchymal stem cells (BM-MSCs) in the repair of damaged myocardium. The molecular mechanisms of engraftment and migration of BM-MSCs in the ischemic myocardium are unknown. In this study, we developed a functional genomics approach toward the identification of mediators of engraftment and migration of BM-MSCs within the ischemic myocardium. Our strategy involves microarray profiling (>22,000 probes) of ischemic hearts, complemented by reverse transcription-polymerase chain reaction and fluorescence-activated cell sorting of corresponding adhesion molecule and cytokine receptors in BM-MSCs to focus on the coexpressed pairs only. Our data revealed nine complementary adhesion molecules and cytokine receptors, including integrin β1, integrin α4, and CXC chemokine receptor 4 (CXCR4). To examine their functional contributions, we first blocked selectively these receptors by preincubation of BM-MSCs with specific neutralizing antibodies, and then we administered these cells intramyocardially. A significant reduction in the total number of BM-MSC in the infarcted myocardium was observed after integrin β1 blockade but not integrin α4 or CXCR4 blockade. The latter observation is distinctively different from that reported for hematopoietic stem cells (HSCs). Thus, our data show that BM-MSCs use a different pathway from HSCs for intramyocardial trafficking and engraftment.
Myosin Vb Interacts with Rab8a on a Tubular Network Containing EHD1 and EHD3
Authors: Roland Joseph T. , Kenworthy Anne K. , Peranen Johan , Caplan Steve , Goldenring James R.
Published: May 2007

Cells use multiple pathways to internalize and recycle cell surface components. Although Rab11a and Myosin Vb are involved in the recycling of proteins internalized by clathrin-mediated endocytosis, Rab8a has been implicated in nonclathrin-dependent endocytosis and recycling. By yeast two-hybrid assays, we have now demonstrated that Myosin Vb can interact with Rab8a, but not Rab8b. We have confirmed the interaction of Myosin Vb with Rab11a and Rab8a in vivo by using fluorescent resonant energy transfer techniques. Rab8a and Myosin Vb colocalize to a tubular network containing EHD1 and EHD3, which does not contain Rab11a. Myosin Vb tail can cause the accumulation of both Rab11a and Rab8a in collapsed membrane cisternae, whereas dominant-negative Rab11-FIP2(129-512) selectively accumulates Rab11a but not Rab8a. Additionally, dynamic live cell imaging demonstrates distinct pathways for Rab11a and Rab8a vesicle trafficking. These findings indicate that Rab8a and Rab11a define different recycling pathways that both use Myosin Vb.
Incidence of Propofol Infusion Syndrome during Noninvasive Radiofrequency Ablation for Atrial Flutter or Fibrillation
Authors: Cravens Grant T. , Packer Douglas L. , Johnson Michael E.
Published: May 2007

Background

Propofol infusion syndrome is first manifest by unexplained metabolic acidosis. Its incidence is unknown.

Methods

Charts of all patients undergoing nonsurgical, catheter radiofrequency ablation for atrial flutter or fibrillation from 1999 through 2001 at Mayo Clinic Rochester, who received propofol and had an arterial blood gas drawn during the procedure, were reviewed retrospectively for metabolic acidosis, prospectively defined as base excess -2 or less. Of 301 radiofrequency ablation cases, 55 had an arterial blood gas. Virtually all radiofrequency ablation patients received propofol, so they could not be used as nonpropofol controls. Instead, all carotid endarterectomy patients in 2000 who did not receive propofol and had an arterial blood gas drawn after anesthetic induction and before surgical incision were used as a comparator group.

Results

In propofol radiofrequency ablation patients with no apparent cause of metabolic acidosis besides propofol, 13 of 55 (24%) had base excess of -2 or less, versus 22 of 267 carotid patients (8.2%) (P<0.01). Maximal negative base excess was -4.2+/-1.7 in these propofol patients and was not correlated with propofol dose, age, or fluid dose, versus base excess of -3.2+/-1.5 in carotid patients (P>0.05). Propofol patients received prolonged anesthetics (7 h) and high-dose propofol (20 mg/kg).

Conclusions

This is the first incidence estimate of metabolic acidosis during prolonged propofol infusion and suggests that it is not rare. The study is limited by its retrospective nature and by the lack of baseline arterial blood gas data and will require confirmation by prospective study.
Volume Replacement Therapy during Major Orthopedic Surgery Using Voluven® (Hydroxyethyl Starch 130/0.4) or Hetastarch
Authors: Gandhi Sweeta D. , Weiskopf Richard B. , Jungheinrich Cornelius , Koorn Robert , Miller Diane , Shangraw Robert E. , Prough Donald S. , Baus Daniela , Bepperling Frank , Warltier David C.
Published: May 2007

Background

The purpose of this study was to test the equivalence of efficacy and compare the safety of the 6% hydroxyethyl starches (HES) Voluven (HES 130/0.4; Fresenius Kabi, Bad Homburg, Germany) and hetastarch (HES 670/0.75 in saline) for intravascular volume replacement therapy during major orthopedic surgery.

Methods

In a prospective, controlled, randomized, double-blind, multicenter trial of patients undergoing major orthopedic surgery, 49 patients were treated with HES 130/0.4 and 51 patients were treated with hetastarch. Infusion of colloids was guided by central venous and arterial blood pressures. The primary efficacy endpoint was the volume of colloid solution infused; the primary safety endpoints were calculated total erythrocyte loss, the nadir factor VIII activity, and the nadir von Willebrand factor concentration within 2 h of completion of surgery.

Results

The total volume of colloid solution required for intraoperative volume replacement did not differ between HES 130/0.4 and hetastarch (1,613+/-778 [SD] ml for HES 130/0.4 and 1,584+/-958 ml for hetastarch). The nadir factor VIII activity within 2 h of the end of surgery was lower for hetastarch than for HES 130/0.4 (P=0.0499); for those who received greater than 1,000 ml colloid, the nadir factor VIII activity and von Willebrand factor concentration within 2 h of end of surgery were lower for hetastarch than for HES 130/0.4 (P=0.0487 and P=0.008, respectively).

Conclusion

Voluven (HES 130/0.4) and hetastarch are equally efficacious plasma volume substitutes; however, HES 130/0.4 has a lesser effect on coagulation.
N-Terminal Pro-brain Natriuretic Peptide Identifies Patients at High Risk for Adverse Cardiac Outcome after Vascular Surgery
Authors: Mahla Elisabeth , Baumann Anneliese , Rehak Peter , Watzinger Norbert , Vicenzi Martin N. , Maier Robert , Tiesenhausen Kurt , Metzler Helfried , Toller Wolfgang
Published: May 2007

Background

Preoperative N-terminal pro-BNP (NT-proBNP) is independently associated with adverse cardiac outcome but does not anticipate the dynamic consequences of anesthesia and surgery. The authors hypothesized that a single postoperative NT-proBNP level provides additional prognostic information for in-hospital and late cardiac events.

Methods

Two hundred eighteen patients scheduled to undergo vascular surgery were enrolled and followed up for 24-30 months. Logistic regression and Cox proportional hazards model were performed to evaluate predictors of in-hospital and long-term cardiac outcome. The optimal discriminatory level of preoperative and postoperative NT-proBNP was determined by receiver operating characteristic analysis.

Results

During a median follow-up of 826 days, 44 patients (20%) experienced 51 cardiac events. Perioperatively, median NT-proBNP increased from 215 to 557 pg/ml (interquartile range, 83/457 to 221/1178 pg/ml; P<0.001). The optimum discriminate threshold for preoperative and postoperative NT-proBNP was 280 pg/ml (95% confidence interval, 123-400) and 860 pg/ml (95% confidence interval, 556-1,054), respectively. Adjusted for age, previous myocardial infarction, preoperative fibrinogen, creatinine, high-sensitivity C-reactive protein, type, duration, and surgical complications, only postoperative NT-proBNP remained significantly associated with in-hospital (adjusted hazard ratio, 19.8; 95% confidence interval, 3.4-115) and long-term cardiac outcome (adjusted hazard ratio, 4.88; 95% confidence interval, 2.43-9.81).

Conclusion

A single postoperative NT-proBNP determination provides important additional prognostic information to preoperative levels and may support therapeutic decisions to prevent subsequent structural myocardial damage.
A Series of Anesthesia-related Maternal Deaths in Michigan, 1985–2003
Authors: Mhyre Jill M. , Riesner Monica N. , Polley Linda S. , Naughton Norah N.
Published: May 2007

Background

Maternal Mortality Surveillance has been conducted by the State of Michigan since 1950, and anesthesia-related maternal deaths were most recently reviewed for the years 1972-1984.

Methods

Records for pregnancy-associated deaths between 1985 and 2003 were reviewed to identify 25 cases associated with a perioperative arrest or major anesthetic complication. Four obstetric anesthesiologists independently classified these cases, and disagreements were resolved by discussion. Precise definitions of anesthesia-related and anesthesia-contributing maternal death were constructed. Anesthesia-related deaths were reviewed to identify the chain of medical errors or care management problems that contributed to each patient death.

Results

Of 855 pregnancy-associated deaths, 8 were anesthesia-related and 7 were anesthesia-contributing. There were no deaths during induction of general anesthesia. Five resulted from hypoventilation or airway obstruction during emergence, extubation, or recovery. Lapses in either postoperative monitoring or anesthesiology supervision seemed to contribute to 5 of the 8 anesthesia-related deaths. Other characteristics common to these cases included obesity (n=6) and African-American race (n=6).

Conclusions

The 8 anesthesia-related and seven anesthesia-contributing maternal deaths in Michigan between 1985 and 2003 illustrate three key points. First, all anesthesia-related deaths from airway obstruction or hypoventilation took place during emergence and recovery, not during the induction of general anesthesia. Second, system errors played a role in the majority of cases. Of concern, lapses in postoperative monitoring and inadequate supervision by an anesthesiologist seemed to contribute to more than half of the deaths. Finally, this report confirms previous work that obesity and African-American race are important risk factors for anesthesia-related maternal mortality.
Respiratory Variations in Pulse Oximetry Plethysmographic Waveform Amplitude to Predict Fluid Responsiveness in the Operating Room
Authors: Cannesson Maxime , Attof Yassin , Rosamel Pascal , Desebbe Olivier , Joseph Pierre , Metton Olivier , Bastien Olivier , Lehot Jean-Jacques
Published: May 2007

Background

Respiratory variations in pulse oximetry plethysmographic waveform amplitude (DeltaPOP) are related to respiratory variations in pulse pressure (DeltaPP) and are sensitive to changes in preload. The authors hypothesized that DeltaPOP can predict fluid responsiveness in mechanically ventilated patients during general anesthesia.

Methods

Twenty-five patients referred for cardiac surgery were studied after induction of general anesthesia. Hemodynamic data (cardiac index, central venous pressure, pulmonary capillary wedge pressure, DeltaPP, and DeltaPOP) were recorded before and after volume expansion (500 ml hetastarch, 6%). Fluid responsiveness was defined as an increase in cardiac index of 15% or greater.

Results

Volume expansion induced changes in cardiac index (2.0+/-0.4 to 2.3+/-0.5 mmHg; P<0.05), DeltaPP (11+/-7 to 6+/-5%; P<0.05), and DeltaPOP (12+/-9 to 7+/-5%; P<0.05). DeltaPOP and DeltaPP were higher in responders than in nonresponders (17+/-8 vs. 6+/-4 and 14+/-7 vs. 6+/-4%, respectively; P<0.05 for both). A DeltaPOP greater than 13% before volume expansion allowed discrimination between responders and nonresponders with 80% sensitivity and 90% specificity. There was a significant relation between DeltaPOP before volume expansion and percent change in cardiac index after volume expansion (r=0.62; P<0.05).

Conclusions

DeltaPOP can predict fluid responsiveness noninvasively in mechanically ventilated patients during general anesthesia. This index has potential clinical applications.
Long-term Effects of Botulinum Toxin on Neuromuscular Function
Authors: Frick Christiane G. , Richtsfeld Martina , Sahani Nita D. , Kaneki Masao , Blobner Manfred , Martyn J A. Jeevendra
Published: May 2007

Background

Recent reports indicate increased incidence of Clostridium botulinum infections, particularly among drug abusers and tissue allograft recipients. Botulinum toxin also has potential application in biochemical warfare. The neurotoxin-induced paralysis often requires mechanical ventilation with and without muscle relaxants. The authors investigated the long-term effects of botulinum toxin on muscle function, expression of nicotinic acetylcholine receptors (nAChRs), and their interaction with muscle relaxant, atracurium.

Methods

Rats (n=30) were injected with varying doses (0.625, 2.5, and 10 U) of botulinum toxin into the tibialis muscle. Control animals (n=9) received an equivalent volume of saline. At 128 days after injection, neuromuscular function, pharmacodynamics of atracurium, and nAChRs were evaluated.

Results

Nerve-evoked tensions, including tetanic tension and muscle mass, were decreased on the toxin-injected side in a dose-dependent manner relative to saline-injected controls as well as the contralateral side. Specific muscle tension and specific tetanic muscle tension (tensions/muscle mass) were not reduced. The ED10 of atracurium was reduced, the ED50 was unchanged, and the ED90 was increased in the highest (10-U) dose of toxin group. The atracurium plasma concentration to maintain a steady state 50% paralysis was significantly reduced in the 10-U toxin group. The nAChR concentrations in the tibialis muscle were significantly increased in a dose-dependent manner in all experimental groups.

Conclusion

Botulinum toxin causes dose-dependent long-term neuromuscular changes. The loss of tension generating capacity is almost exclusively related to muscle atrophy, because the specific tension did not change. The decreased ED10, unaltered ED50, and increased ED90 to atracurium suggest its interactions with different isoforms of receptors having varying sensitivity to atracurium. The absence of fade, despite the persistent botulinum toxin-induced denervation (increased nAChRs), suggests that the up-regulated nAChRs may have compensated for the prejunctional effects of botulinum toxin.
Cholinergic Modulation of Sevoflurane Potency in Cortical and Spinal Networks In Vitro
Authors: Grasshoff Christian , Drexler Berthold , Hentschke Harald , Thiermann Horst , Antkowiak Bernd
Published: May 2007

Background

Victims of organophosphate intoxication with cholinergic crisis may have need for sedation and anesthesia, but little is known about how anesthetics work in these patients. Recent studies suggest that cholinergic stimulation impairs gamma-aminobutyric acid type A (GABAA) receptor function. Because GABAA receptors are major targets of general anesthetics, the authors investigated interactions between acetylcholine and sevoflurane in spinal and cortical networks.

Methods

Cultured spinal and cortical tissue slices were obtained from embryonic and newborn mice. Drug effects were assessed by extracellular voltage recordings of spontaneous action potential activity.

Results

Sevoflurane caused a concentration-dependent decrease in spontaneous action potential firing in spinal (EC50=0.17+/-0.02 mM) and cortical (EC50=0.29+/-0.01 mM) slices. Acetylcholine elevated neuronal excitation in both preparations and diminished the potency of sevoflurane in reducing action potential firing in cortical but not in spinal slices. This brain region-specific decrease in sevoflurane potency was mimicked by the specific GABAA receptor antagonist bicuculline, suggesting that (1) GABAA receptors are major molecular targets for sevoflurane in the cortex but not in the spinal cord and (2) acetylcholine impairs the efficacy of GABAA receptor-mediated inhibition. The latter hypothesis was supported by the finding that acetylcholine reduced the potency of etomidate in depressing cortical and spinal neurons.

Conclusions

The authors raise the question whether cholinergic overstimulation decreases the efficacy of GABAA receptor function in patients with organophosphate intoxication, thereby compromising anesthetic effects that are mediated predominantly via these receptors such as sedation and hypnosis.
Amnesic Concentrations of the Nonimmobilizer 1,2-Dichlorohexafluorocyclobutane (F6, 2N) and Isoflurane Alter Hippocampal θ Oscillations In Vivo
Authors: Perouansky Misha , Hentschke Harald , Perkins Mark , Pearce Robert A.
Published: May 2007

Background

Drug-induced temporary amnesia is one of the principal goals of general anesthesia. The nonimmobilizer 1,2-dichlorohexafluorocyclobutane (F6, also termed 2N) impairs hippocampus-dependent learning at relative, i.e., lipophilicity-corrected, concentrations similar to isoflurane. Hippocampal theta oscillations facilitate mnemonic processes in vivo and synaptic plasticity (a cellular model of memory) in vitro and are thought to represent a circuit level phenomenon that supports memory encoding. Therefore, the authors investigated the effects of F6 and isoflurane on theta oscillations (4-12 Hz).

Methods

Thirteen adult rats were implanted with multichannel depth electrodes to measure the microelectroencephalogram and were exposed to a range of concentrations of isoflurane and F6 spanning the concentrations that produce amnesia. Five of these animals also underwent control experiments without drug injection. The authors recorded the behavioral state and hippocampal field potentials. They confirmed the electrode location postmortem by histology.

Results

The tested concentrations for isoflurane and F6 ranged from 0.035% to 0.77% and from 0.5% to 3.6%, respectively. Isoflurane increased the fraction of time that the animals remained immobile, consistent with sedation, whereas F6 had the opposite effect. Electroencephalographic power in the theta band was less when the animals were immobile than when they explored their environment. F6 suppressed the power of oscillations in the theta band. Isoflurane slowed theta oscillations without reducing total power in the theta band.

Conclusions

Drug-induced changes in theta oscillations may be a common basis for amnesia produced by F6 and isoflurane. The different patterns suggest that these drugs alter network activity by acting on different molecular and/or cellular targets.