bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparative Study on Five Different Commercial Extenders for Boar Semen
Authors: Vyt P , Maes D , Dejonckheere E , Castryck F , Van Soom A
Published: January 2004

Contents

Increasing interest in a longer preservation of diluted boar sperm raises questions in the field concerning the choice of the extender. The aim of this study was to evaluate the longevity of boar sperm extended in currently used commercial semen extenders. Three long‐term extenders and two short‐term extenders were compared for different semen quality parameters that can be assessed under routine laboratory conditions. Sperm morphology, motility, pH and bacteriological contamination were investigated during a 7‐day period. The number of dead spermatozoa did not differ significantly among the extenders (p > 0.05). Sperm motility was not only related with storage period but most of all with pH, especially in long‐term extenders. Differences between the different extenders were prominent (p < 0.05); the sperm preserved in only one long‐term extender showed good motility during the whole test period. In all cases, the pH of the extended semen increased by 0.3–0.5 in the first days of storage and was significantly correlated with a decrease in motility. Bacteriological quality had no significant influence on motility or pH of the semen. In conclusion, we can state that in both short‐term extenders and in only one long‐term extender, sperm longevity, as evaluated by the parameters used in this study, was sufficient during the preservation period. To preserve the quality of diluted boar semen during long‐term storage, the choice of the long‐term extender is important. In addition, the monitoring of the pH of extended boar semen in our study emphasizes the importance of the buffering capacity of semen extenders.
Stage‐specific Expression of Leukaemia Inhibitory Factor and its Receptor in Rabbit Pre‐implantation Embryo and Uterine Epithelium During Early Pregnancy
Authors: Lei T , Yang ZQ , Xia T , Gan L , Chen XD , Yuan JH , Zhu Y
Published: January 2004

Contents

Leukaemia inhibitory factor (LIF) has been shown to play an important role in the development and implantation of blastocysts in mice. In the current study, the reverse transcription–polymerase chain reaction (RT‐PCR) was employed to examine the expression patterns of LIF and its receptor (LIFR) genes in rabbit embryos during pre‐implantation development, and the uterine expression of LIF and LIFR was also evaluated by Western blotting. Transcripts for LIFR were detected within morula and blastocyst‐stage embryos, while the LIF mRNA was only found in blastocysts (from early to fully expanded blastocoel cavities), indicating that embryo‐derived LIF can act in an autocrine manner on the process of blastocyst formation. The expression levels of LIF and LIFR in uterine epithelium were gradually increased during pre‐implantation period and reached their highest levels on days 6.5 of pregnancy, just before the time of blastocyst implantation, suggest that paracrine LIF circuit should exist between the endometrium and the early embryos, which may be involved in the embryo‐maternal dialogue and important for the blastocyst implantation. The data present here show the stage‐specific and dynamic expression patterns of LIF and LIFR, both in embryos and endometrium, during early pregnancy in rabbits, which indicated that LIF might play an important role in the pre‐implantation development and subsequent implantation of rabbit embryos.
Stored of Hsp72/Hsp73 in Germinal Vesicle‐stage Mouse Oocytes
Authors: Liu C‐H , Yang C‐C , Lin DP‐C , Wu M‐H , Tsai K‐J
Published: January 2004

Contents

Heat‐shock proteins (hsps) Hsp72 and Hsp73 are the stored maternal proteins found in mouse oocytes. Both hsps appear in mouse oocytes at germinal vesicle (GV) and metaphase II (M‐II)‐stages as previously demonstrated by immunoblotting analysis. In this report, we further determined the presences of Hsp72/Hsp73 proteins in mouse embryos at stages of 2‐pronucleus, arrested 1‐cell, 2‐cell, arrested 2‐cell, 4‐cell, arrested 4‐cell, 8‐cell to morula and blastocyst. Except for the blastocyst stage, the Hsp72/Hsp73 proteins were detectable in most embryo stages. The concentration of Hsp72/Hsp73 in GV‐stage oocytes was higher than that in M‐II‐stage oocytes, and in any stages of embryos before implantation. A dramatical increase in Hsp72/Hsp73 expression was found at the 2‐cell stage. Together with these findings, we speculated that hsps accumulated or stored earlier in the GV‐stage mouse oocytes to protect the oocytes against environmental influences acting on ovary, and hsps may be required for zygotic gene activation and provided a protective effect against apoptosis.
In vitro Development of Buffalo Oocytes in Media‐containing Fluids from Different Size Class Follicles
Authors: Nandi S , Raghu HM , Ravindranatha BM , Gupta PSP , Sarma PV
Published: January 2004

Contents

Studies were conducted to investigate the effect of supplementation of fluid from different sized class [small (SFF, <3 mm), medium (MFF, 3–8 mm) and large (LFF, >8 mm)] of normal and cystic (CFF) ovarian follicles in oocyte culture media on oocyte maturation rate and embryo development in vitro and to test the efficacy of follicular fluid (FF) from different size classes as a whole oocyte maturation medium. Results suggested that FF were capable of developing buffalo oocytes to embryonic stage in vitro although its efficacy was lower than that of serum. Regardless of high maturation rates after in vitro maturation (IVM) in media containing FF or IVM in whole FF, low blastocyst rates were obtained after in vitro fertilization (IVF) and culture of embryos. Follicular fluid from small follicles had significantly (p < 0.05) higher potential of developing buffalo oocytes to embryonic stage in vitro than that from medium and large follicles. Cystic FF was not capable of supporting development of buffalo oocytes in vitro.
Poly(ADP‐Ribose) Glycohydrolase in Bovine Retained and Not Retained Placenta
Authors: Kankofer M , Guz L , Wierciński J
Published: January 2004

Contents

Poly(ADP‐ribose) glycohydrolase (PARG) is the enzyme which degrades poly(ADP‐ribose) polymers synthesized by poly(ADP‐ribose) polymerase (PARP). Both enzymes are activated in response to different stimuli like oxidative stress and are involved in DNA repair processes. The retention of bovine foetal membranes (RFM) is supposed to be connected with oxidative stress conditions. The aim of the study was to detect the presence of PARG protein in bovine placenta in order to find the relationship between the process of releasing/retaining placenta and DNA repair. Placentomes, collected after spontaneous delivery or caesarian section were divided into maternal as well as foetal part of placenta, homogenized and subjected to electrophoresis. Animals were divided into six groups as follows: A – caesarian section before term with RFM; B – caesarian section before term without RFM; C – spontaneous delivery at term with RFM; D – spontaneous delivery at term without RFM; E – caesarian section at term with RFM; F – caesarian section at term without RFM. PARG protein was detected in nitrocellulose membranes using commercially available bovine anti‐PARG antibody and Western blotting technique. Single bands referred to bovine PARG standard were observed in all examined tissues as well as in human placenta used as the control of procedure. In addition, the intensity of staining was stronger in retained than properly released term placenta and in foetal than in maternal part of the placenta. These results may suggest the differences in enzyme protein content and careful conclusions can be drawn that the activities of PARG may be altered between compared groups of animals. It may confirm the presence of oxidative stress conditions and their consequences on metabolic pathways, the content of biologically active substances and processes of proper releasing placenta. Further experiments on PARG activity in bovine foetal membranes with respect to proper and improper placental release are necessary.
Benign Fibrous Histiocytoma of Prepuce in the Mule
Authors: Rapisarda G , Marino F , Ferrara G , Gioffrè F , Galofaro V
Published: January 2004

Contents

Here we present a case of preputial benign fibrous histiocytoma in a 7‐year‐old mule. This case was treated surgically. Pathologic analysis and diagnosis of these lesions were based on a combination of light microscopy and immunohistochemistry. Histologically, the tumour was composed primarily of a storiform pattern of fibroblastic and poligonal cells. In immunohistochemistry, except for consistent immunoreactivity for vimentin, nearly all tumour cells were positive for CD68, S‐100 protein, pan‐cytokeratin, alpha‐smooth muscle actin, and desmin. Benign fibrous histiocytoma of the prepuce in mule is rarely reported in veterinary literature.
Pregnancy Diagnosis in Miniature Pig by Direct ELISA of Oestrone Derivatives in Faeces
Authors: Isobe N , Nakao T
Published: January 2004

Contents

The objectives of the present study were to measure oestrone derivatives [oestrone, oestrone sulphate (E1S) and oestrone glucuronide] in sow faeces by direct enzyme‐linked immunosorbent assay (ELISA) and to explore the changes of oestrone derivative profile in faeces of miniature pig for demonstrating the possibility of pregnancy diagnosis. Faecal samples (1.5 g) were put into 6 ml of buffer, shaken and centrifuged. Then supernatant was added to the wells of multi‐plate without extraction and incubated with anti‐oestrone antibody and horseradish peroxidase‐labelled oestrone. Standard solution was prepared at various concentrations of E1S. Sensitivity was estimated as 0.035 ng/ml (0.14 ng/g). Intra‐ and inter‐assay coefficient variations were 3.5–7.7% and 10.9–15.3%, respectively. When 1–5 ng/ml E1S were added to a faecal solution, recovery rates ranged between 80.0 and 103.3%. There is a temporal increase in the E1S equivalent concentration of miniature pig faeces from day 25 to 31 after mating. From day 35 to 70, the E1S equivalent concentrations remained low. Thereafter its concentrations increased again towards farrowing. On day 27 and 29 after mating pregnancy diagnosis by the faecal E1S equivalent concentrations agreed with the results of farrowing (seven of seven animals). These results suggest that the present direct ELISA is practical and suitable as a routine assay for measuring the faecal concentration of oestrone derivatives and that this assay might be usable for pregnancy diagnosis in sows at day 27–29.
Flow Cytometry Identification of X‐ and Y‐Chromosome‐Bearing Goat Spermatozoa
Authors: Parrilla I , Vazquez JM , Roca J , Martinez EA
Published: January 2004

Contents

Flow cytometric sorting technology was used to measure the difference in DNA content between X‐ and Y‐chromosome‐bearing spermatozoa in bucks. Spermatozoa were analysed by flow cytometry to characterize X‐ and Y‐chromosome‐bearing sperm populations and to quantify the DNA difference between them. Two symmetrical, overlapping and clearly separated peaks, corresponding to X‐ and Y‐bearing spermatozoa, were detected. The difference in fluorescence intensity between the peaks was 4.4 ± 0.03% without any significant inter‐ or intra‐animal variations. Therefore, the identification and selection of high‐purity samples of sperm populations for sex sorting is easier in bucks compared with other domestic species.
Analogies between colored Lévy noise and random channel approach to disordered kinetics
Authors: Vlad Marcel O. , Velarde Manuel G. , Ross John
Published: January 2004

We point out some interesting analogies between colored Lévy noise and the random channel approach to disordered kinetics. These analogies are due to the fact that the probability density of the Lévy noise source plays a similar role as the probability density of rate coefficients in disordered kinetics. Although the equations for the two approaches are not identical, the analogies can be used for deriving new, useful results for both problems. The random channel approach makes it possible to generalize the fractional Uhlenbeck–Ornstein processes (FUO) for space- and time-dependent colored noise. We describe the properties of colored noise in terms of characteristic functionals, which are evaluated by using a generalization of Huber’s approach to complex relaxation [Phys. Rev. B 31, 6070 (1985)]. We start out by investigating the properties of symmetrical white noise and then define the Lévy colored noise in terms of a Langevin equation with a Lévy white noise source. We derive exact analytical expressions for the various characteristic functionals, which characterize the noise, and a functional fractional Fokker–Planck equation for the probability density functional of the noise at a given moment in time. Second, by making an analogy between the theory of colored noise and the random channel approach to disordered kinetics, we derive fractional equations for the evolution of the probability densities of the random rate coefficients in disordered kinetics. These equations serve as a basis for developing methods for the evaluation of the statistical properties of the random rate coefficients from experimental data. Special attention is paid to the analysis of systems for which the observed kinetic curves can be described by linear or nonlinear stretched exponential kinetics.
Star exponentials for any ordering of the elements of the inhomogeneous symplectic Lie algebra
Authors: Maillard Jean-Marie
Published: January 2004

We compute for any ordering the star exponentials of all polynomials of degree not greater than two on the 2ℓ-dimensional phase space of a quantum system with ℓ degrees of freedom, and we show in the particular case of the Moyal star product that the Weyl transform of the Moyal star exponential of the one-dimensional harmonic oscillator Hamiltonian is the evolution operator of this quantum system.
The Euler characteristic and the first Chern number in the covariant phase space formulation of string theory
Authors: Cartas-Fuentevilla R.
Published: January 2004

Using a covariant description of the geometry of deformations for extendons, it is shown that the topological corrections for the string action associated with the Euler characteristic and the first Chern number of the normal bundle of the world sheet, although do not give dynamics to the string, modify the symplectic properties of the covariant phase space of the theory. Future extensions of the present results are outlined.
Existence of mesons and mass splitting in strong coupling lattice quantum chromodynamics
Authors: Neto A. Francisco , Faria da Veiga P. A. , O’Carroll M.
Published: January 2004

We consider one flavor lattice quantum chromodynamics in the imaginary time functional integral formulation for space dimensions d=2, 3 with 4×4 Dirac spin matrices, small hopping parameter κ, 0<κ≪1, and zero plaquette coupling. We determine the energy-momentum spectrum associated with four-component gauge invariant local meson fields which are composites of a quark and an antiquark field. For the associated correlation functions, we establish a Feynman–Kac formula and a spectral representation. Using this representation, we show that the mass spectrum consists of two distinct masses ma and mb, given by mc=−2 ln κ+rc(κ), c=a,b, where rc is real analytic. For d=2, ma and mb have multiplicity two and the mass splitting is κ4+O(κ6); for d=3, one mass has multiplicity one and the other three, with mass splitting 2κ4+O(κ6). In the subspace of the Hilbert space generated by an even number of fermion fields the dispersion curves are isolated (upper gap property) up to near the two-meson threshold of asymptotic mass −4 ln κ.
The role of M cells and the long QT syndrome in cardiac arrhythmias: Simulation studies of reentrant excitations using a detailed electrophysiological model
Authors: Henry Hervé , Rappel Wouter-Jan
Published: January 2004

In this numerical study, we investigate the role of intrinsic heterogeneities of cardiac tissue due to M cells in the generation and maintenance of reentrant excitations using the detailed Luo–Rudy dynamic model. This model has been extended to include a description of the long QT 3 syndrome, and is studied in both one dimension, corresponding to a cable traversing the ventricular wall, and two dimensions, representing a transmural slice. We focus on two possible mechanisms for the generation of reentrant events. We first investigate if early-after-depolarizations occurring in M cells can initiate reentry. We find that, even for large values of the long QT strength, the electrotonic coupling between neighboring cells prevents early-after-depolarizations from creating a reentry. We then study whether M cell domains, with their slow repolarization, can function as wave blocks for premature stimuli. We find that the inclusion of an M cell domain can result in some cases in reentrant excitations and we determine the lifetime of the reentry as a function of the size and geometry of the domain and of the strength of the long QT syndrome.
Relativistic stars in differential rotation: bounds on the dragging rate and on the rotational energy
Authors: Pareja M. J.
Published: January 2004

For general relativistic equilibrium stellar models (stationary axisymmetric asymptotically flat and convection-free) with differential rotation, it is shown that for a wide class of rotation laws the distribution of angular velocity of the fluid has a sign, say “positive,” and then both the dragging rate and the angular momentum density are positive. In addition, the “mean value” (with respect to an intrinsic density) of the dragging rate is shown to be less than the mean value of the fluid angular velocity (in full general, without having to restrict the rotation law, nor the uniformity in sign of the fluid angular velocity); this inequality yields the positivity and an upper bound of the total rotational energy.
Existence of initial data satisfying the constraints for the spherically symmetric Einstein–Vlasov–Maxwell system
Authors: Noundjeu P. , Noutchegueme N. , Rendall A. D.
Published: January 2004

Using ODE techniques we prove the existence of large classes of initial data satisfying the constraints for the spherically symmetric Einstein–Vlasov–Maxwell system. These include data for which the ratio of total charge to total mass is arbitrarily large.
Warped product approach to universe with nonsmooth scale factor
Authors: Choi Jaedong , Hong Soon-Tae
Published: January 2004

In the framework of Lorentzian warped products, we study the Friedmann–Robertson–Walker cosmological model to investigate nonsmooth curvatures associated with multiple discontinuities involved in the evolution of the universe. In particular we analyze nonsmooth features of the spatially flat Friedmann–Robertson–Walker universe by introducing double discontinuities occurred at the radiation-matter and matter-lambda phase transitions in astrophysical phenomenology.
2-geometries and the Hamilton–Jacobi equation
Authors: Garcı́a-Godı́nez Patricia , Newman Ezra Ted , Silva-Ortigoza Gilberto
Published: January 2004

By using two different procedures we show that on the space of solutions of a certain class of second-order ordinary differential equations, u″=Λ(s,u,u′), a two-dimensional definite or indefinite metric, gab, can be constructed such that the two-dimensional Hamilton–Jacobi equation, gabu,au,b=1 holds. Furthermore, we show that this structure is invariant under a certain subset of contact transformations (canonical transformations). Two examples are given.
On the classification of type D space–times
Authors: Ferrando Joan Josep , Sáez Juan Antonio
Published: January 2004

We give a classification of the type D space–times based on the invariant differential properties of the Weyl principal structure. Our classification is established using tensorial invariants of the Weyl tensor and, consequently, besides its intrinsic nature, it is valid for the whole set of the type D metrics and it applies on both, vacuum and nonvacuum solutions. We consider the Cotton-zero type D metrics and we study the classes that are compatible with this condition. The subfamily of space–times with constant argument of the Weyl eigenvalue is analyzed in more detail by offering a canonical expression for the metric tensor and by giving a generalization of some results about the nonexistence of purely magnetic solutions. The usefulness of these results is illustrated in characterizing and classifying a family of Einstein–Maxwell solutions. Our approach permits us to give intrinsic and explicit conditions that label every metric, obtaining in this way an operational algorithm to detect them. In particular a characterization of the Reissner–Nordström metric is accomplished.
A system of nonlinear algebraic equations connected with the multisoliton solution of the Benjamin–Ono equation
Authors: Matsuno Yoshimasa
Published: January 2004

The multisoliton solution of the Benjamin–Ono equation is derived from the system of nonlinear algebraic equations. This finding is unexpected from the scheme of the inverse scattering transform method, which constructs the multisoliton solution through the system of linear algebraic equations. The anlaysis developed here is also applied to the rational multisoliton solution of the Kadomtsev–Petviashvili equation.
The influence of nitrogen supply on antioxidant enzymes in plant roots
Authors: Medici Leonardo Oliveira , Azevedo Ricardo Antunes , Smith Richard John , Lea Peter John
Published: January 2004

Plants of Zea mays L., Hordeum vulgare L. and Arabidopsis thaliana (L.) Heynh. were grown at different concentrations of nitrogen, as NH4NO3, and the antioxidant enzyme activities and quantities in the roots, were studied. Maize plants were grown at 1 and 10 mM N for 32 d after germination and their roots were analysed by native PAGE for the isoenzymic profiles of glutathione reductase (GR; EC 1.6.4.2), catalase (CAT; EC 1.11.1.6) and superoxide dismutase (SOD; EC 1.15.1.1) and by spectrophotometric assays for total activity of CAT and GR. Barley and A. thaliana plants were grown at five N concentrations (0.25, 0.5, 1, 10 and 20 mM) for 27 and 26 d, respectively, and the isoenzymic profile of the three enzymes were analysed in their roots. The number of GR isoforms in the three plant species was increased at high N supply compared with low N. In addition, the CAT and GR activities detected in the roots were increased in plants grown at higher N. The increase in activity and number of bands of GR at high N in the roots of all three plants studied was not accompanied by a change in activity or the number of SOD isoforms. The possibility that the application of high N promotes the formation of reactive oxygen species by stimulating an increased rate of growth is discussed.
Structural changes in acclimated and unacclimated leaves during freezing and thawing
Authors: Ball Marilyn C. , Canny Martin J. , Huang Chen X. , Heady Roger D.
Published: January 2004

Freeze-induced damage to leaf tissues was studied at different states of acclimation to low temperatures in snow gum, Eucalyptus pauciflora Sieber ex Sprengel. Intact, attached leaves of plants grown under glasshouse or field conditions were frozen at natural rates (frost-freezing) and thawed under laboratory conditions. Leaves were cryo-fixed unfrozen, during frost-freezing or after thawing for observation in a cryo-scanning electron microscope. Frost-freezing in unacclimated tissues caused irreversible tissue damage consistent with tissue death. Intracellular ice formed in the cambium and phloem, killing the cells and leaving persistent gaps between xylem and phloem. Many other cells were damaged by frost-freeze-induced dehydration and failed to resorb water from thawed extracellular ice, leaving substantial amounts of liquid water in intercellular spaces. In contrast, acclimated leaves showed reversible tissue displacements consistent with leaf survival. In these leaves during freezing, massive extracellular ice formed in specific expansion zones within the midvein. On thawing, water was resorbed by living cells, restoring the original tissue shapes. Possible evolutionary significance of these expansion zones is discussed. Acclimated leaves showed no evidence of intracellular freezing, nor tissue lesions caused by extracellular ice. While the observations accord with current views of freeze-sensitivity and tolerance, cryo-microscopy revealed diverse responses in different tissue types.
The 2003 Extenza telemarketing effectiveness survey
Authors: Erzin Pinar
Published: January 2004

An account of the overall results from Extenza telemarketing campaigns in 2003 is given, with details of rates of success.
The ALPSP Learned Journals Collection
Authors: Bonald Laura , Morris Sally
Published: January 2004

Selling journals to consortia and other large customers is increasingly difficult for small publishers, and yet libraries want their journals. The ALPSP Learned Journals Collection (ALJC) was put together, after considerable research, as an attempt to overcome this problem for ALPSP member publishers. Working through Swets Information Services, 247 journals from 25 publishers can be sold as a single package. Despite the difficulties, a single publisher agreement, customer licence, and pricing and revenue‐sharing model were all agreed upon. Customer reactions indicate that this is a real win–win solution for publishers and libraries.
Book Reviews
Authors: Peters John , Beckwith Kimberly M. , Dryburgh Alastair
Published: January 2004

The Bangladesh Journal of Communication and Publishing, Editor: Fazle Rabbi. The Editing and Publication Association of Bangladesh. Subscription (forinstitutions in developed countries) US$50.

Getting and Staying Noticed on the Web by Phil Bradley. Facet Publishing, London, 2002, 219pp. ISBN 1‐85604‐455‐6

The Innovator's Dilemma by Clayton M. Christensen

HarperBusiness 2003, Price $17.95, 285pp. paperback, ISBN 0‐06‐052199‐6
Effects of ε-Aminocaproic Acid and Aprotinin on Leukocyte–Platelet Adhesion in Patients Undergoing Cardiac Surgery
Authors: Greilich Philip E. , Brouse Chad F. , Rinder Christine S. , Smith Brian R. , Sandoval Bernardo A. , Rinder Henry M. , Eberhart Robert C. , Jessen Michael E.
Published: January 2004

Background

The administration of aprotinin during cardiopulmonary bypass (CPB) is hypothesized to decrease activation of leukocytes and platelets and possibly reduce their adhesion. Although epsilon-aminocaproic acid (EACA) shares the ability of aprotinin to inhibit excessive plasmin activity after CPB, its effect on leukocyte and platelet activation and leukocyte-platelet (heterotypic) adhesion is largely unknown. This study was performed to determine the relative effectiveness of the antifibrinolytics, aprotinin and EACA, at reducing leukocyte and platelet activation and leukocyte-platelet conjugate formation in patients undergoing CPB.

Methods

Thirty-six patients scheduled to undergo cardiac surgery with CPB were randomized in a double-blind fashion to receive EACA, aprotinin, or saline (placebo). Markers of plasmin activity (D-dimer concentrations), platelet activation (CD62P), leukocyte activation (CD11b), and leukocyte-platelet adhesion (monocyte- and neutrophil-platelet conjugates) were measured before, during, and after CPB.

Results

Platelet CD62P (P-selectin), monocyte CD11b, and monocyte-platelet conjugates were all significantly increased (compared with baseline) in the saline group during and after CPB. Despite equivalent reductions in D-dimer formation in patients receiving EACA (P < 0.0001) and aprotinin (P < 0.0001), decreases in platelet CD62P and monocyte CD11b expression were incomplete (not significantly different from saline control). In contrast, peak monocyte-platelet conjugate formation was significantly reduced by both EACA (P = 0.026) and aprotinin (P = 0.039) immediately after CPB.

Conclusions

EACA seems to be as effective as aprotinin at reducing peak monocyte-platelet adhesion after CPB. Furthermore, inhibition of excessive plasmin activity seems to influence monocyte-platelet adhesion. The findings suggest that monocyte-platelet conjugate formation may be a useful marker of monocyte and platelet activation in this clinical setting.
Early Onset Pneumonia
Authors: Bronchard Régis , Albaladejo Pierre , Brezac Gilles , Geffroy Arnaud , Seince Pierre-François , Morris William , Branger Catherine , Marty Jean
Published: January 2004

Background

Early onset pneumonia occurs frequently in head trauma patients, but the potential consequences and the risk factors of this event have been poorly studied.

Methods

This prospective observational study was undertaken in the surgical intensive care unit of a university teaching hospital in Clichy, France. Head trauma patients requiring tracheal intubation for neurologic reasons and ventilation for at least 2 days were studied to assess the risk factors and the consequences of early onset pneumonia.

Results

During a 2-yr period, 109 head trauma patients were studied. The authors found an incidence of early onset pneumonia of 41.3%. Staphylococcus aureus was the most common bacteria involved in early onset pneumonia. Patients with early onset pneumonia had a lower worst arterial oxygen tension:fraction of inspired oxygen ratio, more fever, more arterial hypotension, and more intracranial hypertension, factors known to worsen the neurologic prognosis of head trauma patients. Nasal carriage of S. aureus on admission (odds ratio, 5.1; 95% confidence interval, 1.9-14.0), aspiration before intubation (odds ratio, 5.5; 95% confidence interval, 1.9-16.4) and barbiturate use (odds ratio, 3.9; 95% confidence interval, 1.2-12.8) were found to be independent risk factors of early onset pneumonia.

Conclusions

The results suggest that early onset pneumonia leads to secondary injuries in head-injured patients. Nasal carriage of S. aureus, aspiration before intubation, and use of barbiturates are specific independent risk factors for early onset pneumonia and must be assessed to find and evaluate strategies to prevent early onset pneumonia.
Laryngeal Mask Airway Insertion by Anesthetists and Nonanesthetists Wearing Unconventional Protective Gear
Authors: Flaishon Ron , Sotman Alexander , Friedman Alan , Ben-Abraham Ron , Rudick Valery , Weinbroum Avi A.
Published: January 2004

Background

Mass casualty situations impose special difficulties in airway management, even for experienced caregivers. The laryngeal mask airway is part of the difficult airway algorithm. The authors evaluated the success rate and the time to secure airways by mask by anesthetists, surgeons, and novices when wearing either surgical attire or full antichemical protective gear that included butyl rubber gloves and a filtering antigas mask.

Methods

Twenty anesthetists and 22 surgeons with 2-5 yr of residency inserted a laryngeal mask airway in 84 anesthetized patients, and 6 novices repetitively inserted masks in 57 patients under both conditions in a prospective, randomized, crossover manner. The duration of insertion was measured from the time the device was first grasped until a normal capnography recording was obtained.

Results

Anesthetists needed 39 +/- 14 s to insert the masks when wearing surgical attire and 40 +/- 12 s with protective gear. In contrast, surgery residents needed 64 +/- 40 and 102 +/- 40 s (P = 0.0001), respectively. Anesthetists inserted masks in a single attempt, whereas the surgeons needed up to four attempts with no hypoxia or failure associated. The initial attire-wearing novices' insertions took as long as the surgeons'; three of them then reached the mean performance time of the anesthetists after four (protective gear) and two (surgical attire) trials, with only one occurrence of hypoxia and a failure rate similar to that of the surgeons.

Conclusions

Anesthesia residents insert laryngeal mask airways at a similar speed when wearing surgical attire or limiting antichemical protective gear and two to three times faster than surgical residents or novices wearing either outfit. Novices initially perform at the level of surgical residents, but their learning curve was quick under both conditions.
Obesity Decreases Perioperative Tissue Oxygenation
Authors: Kabon Barbara , Nagele Angelika , Reddy Dayakar , Eagon Chris , Fleshman James W. , Sessler Daniel I. , Kurz Andrea
Published: January 2004

Background

Obesity is an important risk factor for surgical site infections. The incidence of surgical wound infections is directly related to tissue perfusion and oxygenation. Fat tissue mass expands without a concomitant increase in blood flow per cell, which might result in a relative hypoperfusion with decreased tissue oxygenation. Consequently, the authors tested the hypotheses that perioperative tissue oxygen tension is reduced in obese surgical patients. Furthermore, they compared the effect of supplemental oxygen administration on tissue oxygenation in obese and nonobese patients.

Methods

Forty-six patients undergoing major abdominal surgery were assigned to one of two groups according to their body mass index: body mass index less than 30 kg/m2 (nonobese) or 30 kg/m2 or greater (obese). Intraoperative oxygen administration was adjusted to arterial oxygen tensions of approximately 150 mmHg and approximately 300 mmHg in random order. Anesthesia technique and perioperative fluid management were standardized. Subcutaneous tissue oxygen tension was measured with a polarographic electrode positioned within a subcutaneous tonometer in the lateral upper arm during surgery, in the recovery room, and on the first postoperative day. Postoperative tissue oxygen was also measured adjacent to the wound. Data were compared with unpaired two-tailed t tests and Wilcoxon rank sum test; P < 0.05 was considered statistically significant.

Results

Intraoperative subcutaneous tissue oxygen tension was significantly less in the obese patients at baseline (36 vs. 57 mmHg; P = 0.002) and with supplemental oxygen administration (47 vs. 76 mmHg; P = 0.014). Immediate postoperative tissue oxygen tension was also significantly less in subcutaneous tissue of the upper arm (43 vs. 54 mmHg; P = 0.011) as well as near the incision (42 vs. 62 mmHg; P = 0.012) in obese patients. In contrast, tissue oxygen tension was comparable in each group on the first postoperative morning.

Conclusion

Wound and tissue hypoxia were common in obese patients in the perioperative period and most pronounced during surgery. Even with supplemental oxygen tissue, oxygen tension in obese patients was reduced to levels that are associated with a substantial increase in infection risk.
Epidural Anesthesia, Hypotension, and Changes in Intravascular Volume
Authors: Holte Kathrine , Foss Nicolai B. , Svensén Christer , Lund Claus , Madsen Jan L. , Kehlet Henrik
Published: January 2004

Background

The most common side effect of epidural or spinal anesthesia is hypotension with functional hypovolemia prompting fluid infusions or administration of vasopressors. Short-term studies (20 min) in patients undergoing lumbar epidural anesthesia suggest that plasma volume may increase when hypotension is present, which may have implications for the choice of treatment of hypotension. However, no long-term information or measurements of plasma volumes with or without hypotension after epidural anesthesia are available.

Methods

In 12 healthy volunteers, the authors assessed plasma (125I-albumin) and erythrocyte (51Cr-EDTA) volumes before and 90 min after administration of 10 ml bupivacaine, 0.5%, via a thoracic epidural catheter (T7-T10). After 90 min (t = 90), subjects were randomized to administration of fluid (7 ml/kg hydroxyethyl starch) or a vasopressor (0.2 mg/kg ephedrine), and 40 min later (t = 130), plasma and erythrocyte volumes were measured. At the same time points, mean corpuscular volume and hematocrit were measured. Systolic and diastolic blood pressure, heart rate, and hemoglobin were measured every 5 min throughout the study. Volume kinetic analysis was performed for the volunteers receiving hydroxyethyl starch.

Results

Plasma volume did not change per se after thoracic epidural anesthesia despite a decrease in blood pressure. Plasma volume increased with fluid administration but remained unchanged with vasopressors despite that both treatments had similar hemodynamic effects. Hemoglobin concentrations were not significantly altered by the epidural blockade or ephedrine administration but decreased significantly after hydroxyethyl starch administration. Volume kinetic analysis showed that the infused fluid expanded a rather small volume, approximately 1.5 l. The elimination constant was 56 ml/min.

Conclusions

Thoracic epidural anesthesia per se does not lead to changes in blood volumes despite a reduction in blood pressure. When fluid is infused, there is a dilution, and the fluid initially seems to be located centrally. Because administration of hydroxyethyl starch and ephedrine has similar hemodynamic effects, the latter may be preferred in patients with cardiopulmonary diseases in which perioperative fluid overload is undesirable.
Wrist Hyperextension Leads to Median Nerve Conduction Block
Authors: Chowet Anne L. , Lopez Jaime R. , Brock-Utne John G. , Jaffe Richard A.
Published: January 2004

Background

It is common practice to hyperextend the wrist to facilitate insertion of a radial intra-arterial catheter. This position may be maintained for prolonged periods. Although there has been much discussion about optimal patient management to protect the ulnar nerve and brachial plexus, little attention has been paid to the median nerve during wrist hyperextension. The authors report the effects of wrist hyperextension on conduction in the median nerve.

Methods

Median nerve conduction was studied in 12 awake, healthy volunteers using standard nerve conduction tests consisting of the measurement of compound sensory and motor action potentials, as well as their amplitudes and latencies. With the contralateral hand as a control, the right wrist was placed in hyperextension (angled between 65 and 80 degrees), and compound action potentials were recorded to determine the onset and magnitude of effects. Subsequently, the hand was released from hyperextension and recovery was recorded.

Results

In 83% of subjects, hyperextension resulted in a significant decrease in compound sensory action potential amplitudes, sufficient to qualify as conduction block (16.6% of baseline). The average time to conduction block was 43 +/- 13.2 min. All subjects who manifested conduction block showed marked improvement 5 min after release from hyperextension.

Conclusions

Wrist hyperextension for arterial line placement and stabilization is likely to result in profound impairment of median nerve function. Although the effects were transient in this study, the results suggest that prolonged hyperextension may be associated with significant changes in median nerve conduction. To minimize the chance for nerve injury, the authors recommend that wrists be returned promptly to the neutral position following arterial line placement.
Mechanism by Which a Sustained Inflation Can Worsen Oxygenation in Acute Lung Injury
Authors: Musch Guido , Harris R. Scott , Vidal Melo Marcos F. , O’Neill Kevin R. , Layfield J. Dominick H. , Winkler Tilo , Venegas Jose G.
Published: January 2004

Background

Sustained lung inflations (recruitment maneuvers [RMs]) are occasionally used during mechanical ventilation of patients with acute lung injury to restore aeration to atelectatic alveoli. However, RMs do not improve, and may even worsen, gas exchange in a fraction of these patients. In this study, the authors sought to determine the mechanism by which an RM can impair gas exchange in acute lung injury.

Methods

The authors selected a model of acute lung injury that was unlikely to exhibit sustained recruitment in response to a lung inflation. In five sheep, lung injury was induced by lavage with 0.2% polysorbate 80 in saline. Positron emission tomography and [13N]nitrogen were used to assess regional lung function in dependent, middle, and nondependent lung regions. Physiologic data and positron emission scans were collected before and 5 min after a sustained inflation (continuous positive airway pressure of 50 cm H2O for 30 s).

Results

All animals showed greater loss of aeration and higher perfusion and shunting blood flow in the dependent region. After the RM, Pao2 decreased in all animals by 35 +/- 22 mmHg (P < 0.05). This decrease in Pao2 was associated with redistribution of pulmonary blood flow from the middle, more aerated region to the dependent, less aerated region (P < 0.05) and with an increase in the fraction of pulmonary blood flow that was shunted in the dependent region (P < 0.05). Neither respiratory compliance nor aeration of the dependent region improved after the RM.

Conclusions

When a sustained inflation does not restore aeration to atelectatic regions, it can worsen oxygenation by increasing the fraction of pulmonary blood flow that is shunted in nonaerated regions.
Molecular Mechanisms of the Inhibitory Effects of Propofol and Thiamylal on Sarcolemmal Adenosine Triphosphate–sensitive Potassium Channels
Authors: Kawano Takashi , Oshita Shuzo , Takahashi Akira , Tsutsumi Yasuo , Tomiyama Yoshinobu , Kitahata Hiroshi , Kuroda Yasuhiro , Nakaya Yutaka
Published: January 2004

Background

Both propofol and thiamylal inhibit adenosine triphosphate-sensitive potassium (KATP) channels. In the current study, the authors investigated the effects of these anesthetics on the activity of recombinant sarcolemmal KATP channels encoded by inwardly rectifying potassium channel (Kir6.1 or Kir6.2) genes and sulfonylurea receptor (SUR1, SUR2A, or SUR2B) genes.

Methods

The authors used inside-out patch clamp configurations to investigate the effects of propofol and thiamylal on the activity of recombinant KATP channels using COS-7 cells transfected with various types of KATP channel subunits.

Results

Propofol inhibited the activities of the SUR1/Kir6.2 (EC50 = 77 microm), SUR2A/Kir6.2 (EC50 = 72 microm), and SUR2B/Kir6.2 (EC50 = 71 microm) channels but had no significant effects on the SUR2B/Kir6.1 channels. Propofol inhibited the truncated isoform of Kir6.2 (Kir6.2DeltaC36) channels (EC50 = 78 microm) that can form functional KATP channels in the absence of SUR molecules. Furthermore, the authors identified two distinct mutations R31E (arginine residue at position 31 to glutamic acid) and K185Q (lysine residue at position 185 to glutamine) of the Kir6.2DeltaC36 channel that significantly reduce the inhibition of propofol. In contrast, thiamylal inhibited the SUR1/Kir6.2 (EC50 = 541 microm), SUR2A/Kir6.2 (EC50 = 248 microm), SUR2B/Kir6.2 (EC50 = 183 microm), SUR2B/Kir6.1 (EC50 = 170 microm), and Kir6.2DeltaC36 channels (EC50 = 719 microm). None of the mutants significantly affects the sensitivity of thiamylal.

Conclusions

These results suggest that the major effects of both propofol and thiamylal on KATP channel activity are mediated via the Kir6.2 subunit. Site-directed mutagenesis study suggests that propofol and thiamylal may influence Kir6.2 activity by different molecular mechanisms; in thiamylal, the SUR subunit seems to modulate anesthetic sensitivity.
Effects of the α2-Adrenoceptor Agonist Dexmedetomidine on Bronchoconstriction in Dogs
Authors: Groeben Harald , Mitzner Wayne , Brown Robert H.
Published: January 2004

Background

Tracheal intubation can elicit reflex bronchoconstriction in patients with asthma or chronic obstructive pulmonary disease, complicating mechanical ventilation and weaning from mechanical support. In vitro studies of human and animal bronchial tissue indicate that alpha2-adrenoceptor stimulation can lead to smooth muscle relaxation and prevention of bronchoconstriction. Dexmedetomidine is a selective alpha2-adrenoceptor agonist approved for sedation in the intensive care unit. Whether dexmedetomidine can affect reflex bronchoconstriction is unknown.

Methods

After the approval of the institutional animal care and use committee, five mongrel dogs were anesthetized with thiopental, endotracheally intubated, and ventilated, and their airways were challenged with histamine. High-resolution computed tomography was used to measure airway luminal areas at baseline and after nebulized histamine. After recovery to baseline, on separate days, dexmedetomidine (0.5 microg/kg) was administered either intravenously or as an aerosol, and the histamine challenge was repeated.

Results

At baseline, histamine constricted the airways to 66 +/- 27% (mean +/- SD) (P < 0.0001) and 59 +/- 30% (P < 0.0001) of maximum on the days dexmedetomidine was administered by intravenous and inhalational means, respectively. After recovery, intravenous administration of dexmedetomidine blocked the histamine-induced bronchoconstriction (87 +/- 30.4% of maximum, compared with histamine alone (P < 0.0001), whereas dexmedetomidine administered by inhalation showed no protective effect (45 +/- 30% of maximum; P < 0.0001 compared with histamine alone).

Conclusion

alpha2-Adrenoceptor stimulation with intravenous dexmedetomidine completely blocked histamine-induced bronchoconstriction in dogs. Therefore, dexmedetomidine might be beneficial to decrease airway reactivity in patients with chronic obstructive pulmonary disease or asthma, particularly during weaning from mechanical ventilation, when neurally mediated airway reflexes may be elicited.
Upregulation of Spinal Cyclooxygenase-2 in Rats after Surgical Incision
Authors: Kroin Jeffrey S. , Ling Zao D. , Buvanendran Asokumar , Tuman Kenneth J.
Published: January 2004

Background

Although upregulation of cyclooxygenase (COX)-2 in spinal cord after peripheral inflammation has been well documented, the effect of surgery on spinal COX-2 has not been examined in detail. The present study uses a bilateral foot incision in rats to examine the magnitude and duration of surgically induced changes in spinal COX-2 protein.

Methods

A longitudinal incision was made in both plantar hind paws of isoflurane-anesthetized rats. Spinal cords were removed at various postoperative times (1-48 h), and spinal COX-2 protein levels were compared with the results of Western blot analysis. Ropivacaine-induced blockade of sciatic nerve function was used to determine the importance of afferent nerve activity on spinal COX-2 after incision. Dexamethasone and the COX-2-selective inhibitor L-745,337 were administered intrathecally to modulate spinal COX-2 after incision.

Results

COX-2 protein levels increased in the lumbar spinal cord at 3 (1.32-fold) and 6 (1.26-fold) h after bilateral foot incision. At later times, lumbar COX-2 levels were no different than in control animals not undergoing surgery. Cervical COX-2 protein levels remained unchanged. Sciatic nerve blockade with ropivacaine did not prevent the increase in lumbar spinal COX-2 protein levels after incision. Intrathecal dexamethasone decreased lumbar spinal COX-2 levels after incision, and an intrathecal COX-2-selective inhibitor did not reduce the COX-2 upregulation.

Conclusions

After bilateral foot incision in rats, lumbar spinal COX-2 protein levels increase, although the magnitude and duration are less than reported in models of peripheral inflammation. This COX-2 upregulation does not seem to be mediated by afferent nerve activity.