bluuebunny/crossref_metadata_2025 huggingface dataset:
Spectral analysis of coupled Euler‐Bernoulli and Timoshenko beam model
Authors: Balakrishnan A.V. , Shubov M.A. , Peterson C.A.
Published: March 2004

The present paper is devoted to the asymptotic and spectral analysis of a system of coupled Euler‐Bernoulli and Timoshenko beams. The model is governed by a system of two coupled differential equations and a two parameter family of boundary conditions modelling the action of the self‐straining actuators. The above equations of motion form a coupled linear hyperbolic system, which is equivalent to a single operator evolution equation in the energy space. That equation defines a semigroup of bounded operators. This is a dynamics generator of the semigroup which is our main object of interest in the present paper. We prove that for each set of boundary parameters, the dynamics generator has a compact inverse and this inverse operator belongs to class \documentclass{article}\pagestyle{empty}\usepackage{amsfonts}\begin{document}$\mathfrak{S}_p$\end{document} of compact operators with p > 1. We also show that if both boundary parameters are not purely imaginary numbers, then the dynamics generator is a nonselfadjoint operator in the energy space. However, its inverse operator is a finite‐rank perturbation of a selfadjoint operator. The latter fact is crucial for the proof of the fact that the root vectors of the dynamics generator form a complete and minimal set in the energy space. We will use the spectral results in our forthcoming papers to prove that the dynamics generator of the system is a Riesz spectral operator in the sense of Dunford and to use the latter fact for the solution of several boundary and distributed controllability problems via the spectral decomposition method.
Fundamental matrices of homogeneous hyperbolic systems. Applications to crystal optics, elastodynamics, and piezoelectromagnetism
Authors: Ortner N. , Wagner P.
Published: March 2004

Modifying L. Gårding's derivation in the scalar case we deduce Herglotz‐Petrovsky formulae for fundamental matrices (“Green's tensors”) for real homogeneous hyperbolic systems of partial differential operators. As an application, we calculate the fundamental matrix for elastodynamic systems of hexagonal symmetry with reducible determinant (Props. 1, 2). A special case thereof is the fundamental matrix of the system of uniaxial optics (Prop. 3). The calculations are based on integrals of the type $\int_C ([\xi,p]/[\xi,q]) \delta([\xi,x]) \hbox{d}o(\xi)$ where the 1904. conic section C in \documentclass{article}\pagestyle{empty}\usepackage{amssymb}\begin{document}$\mathbb{R}^4$\end{document} is defined as the intersection of [ξ,ξ] = 0 with [ξ,N] = 1.
A Refinement Strategy for
Circus
Authors: Cavalcanti Ana , Sampaio Augusto , Woodcock Jim
Published: March 2004

We present a refinement strategy for
Circus
, which is the combination of Z, CSP, and the refinement calculus in the setting of Hoare and He’s unifying theories of programming. The strategy unifies the theories of refinement for processes and their constituent actions, and provides a coherent technique for the stepwise refinement of concurrent and distributed programs involving rich data structures. This kind of development is carried out using
Circus
’s refinement calculus, and we describe some of its laws for the simultaneous refinement of state and control behaviour, including the splitting of a process into parallel subcomponents. We illustrate the strategy and the laws using a case study that shows the complete development of a small distributed program.
Mutation Testing in the Refinement Calculus
Authors: Aichernig Bernhard K.
Published: March 2004

This article discusses mutation testing strategies in the context of refinement. Here, a novel generalisation of mutation testing techniques is presented to be applied to contracts ranging from formal specifications to programs. It is demonstrated that refinement and its dual abstraction are the key notions leading to a precise and yet simple theory of mutation testing. The refinement calculus of Back and von Wright is used to express concepts like contracts, useful mutations, test cases and test coverage.
Cancer of the Nasopharynx: Functional Surgical Salvage
Authors: Wei William Ignace
Published: March 2004

The primary treatment modality for nasopharyngeal carcinoma is radiotherapy (RT). When tumor persists or recurs at the nasopharynx or in the neck after irradiation, then further courses of radiotherapy are associated with recognized morbidities. The swallowing, speech abilities as well as the cervical musculoskeletal functions of the patient may be significantly affected. Surgical salvage of neck disease with radical neck dissection contributes to better tumor control with acceptable morbidity. For localized tumor in the nasopharynx, adequate extirpation of the disease together with the removal of paranasopharyngeal tissue is possible with the anterolateral approach. The operation is not difficult and the associated morbidity is minimal. After a median follow up of 3 years, the 82 patients who underwent this operation demonstrate that with adequate exposure and surgical salvage, satisfactory tumor control rate with good functional outcome is possible.
Definition and Classification of Chronic Pancreatitis
Authors: Keith Roger G.
Published: March 2004

Chronic pancreatitis has been defined by features that are clinical and etiologic in origin. From such definitions a number of classifications have been developed, starting with the Marseille Classification in 1963. Defining features of chronic pancreatitis must consider the etiology of the disease, which then presents characteristic clinical evidence through symptomatic sequelae of organ pathology, including complications of the disease. Advancing technology has improved the imaging capabilities available to document derangements of the pancreas. The main purpose of international classifications of disease states is to provide a common language for purposes of clinical, research, and health outcomes studies. Modification of the 10th World Health Organization I.C.D. classification may provide this tool.
Nerve Blocks and Neuroablative Surgery for Chronic Pancreatitis
Authors: Bradley Edward L. , Bem Jiri
Published: March 2004

Surgical decompressive procedures for “large‐duct” chronic pancreatitis have been notably successful in relieving pain. However, management of patients with intractable pain from “small‐duct” chronic pancreatitis has been difficult, often resulting in narcotic addiction and/or malnutrition from major pancreatic resection. In view of the disappointing results from extensive pancreatic resections in these cases, denervation of pancreatic sympathetic pain afferents has been suggested as an alternative. Although denervation procedures have been attempted at multiple anatomical levels, results have unfortunately been mixed. The observed variability in results has been attributed to poor patient selection, incomplete understanding of neurophysiology of pancreatic pain, and perhaps inadequate knowledge of pancreatic neuroanatomy. At present, the preferred form of neural ablation is splanchnicectomy. However, a consistent and reliable method for identifying candidates for splanchnicectomy is critical, as it is clinically difficult to distinguish true pancreatic pain from other nociceptive conditions masquerading as pancreatic pain. Differential epidural anesthesia (DEA) is a promising, safe test for initial evaluation and patient selection, although it is not as precise as sometimes claimed. Patients responding to sympathetic block during DEA seem to be the best candidates for operative sympathetic ablation. At the moment, the optimal surgical approach to splanchnic ablation, which offers the least morbid technique, most favorable results, and an attractive risk–benefit ratio, is bilateral thoracoscopic splanchnicectomy. More experience and longer follow‐up will be necessary to evaluate this approach.
Carcinoma of the Head of the Pancreas versus Chronic Pancreatitis: Diagnostic Dilemma with Significant Consequences
Authors: Taylor Bryce
Published: March 2004

Although carcinoma of the head of the pancreas and chronic pancreatitis are usually easy to distinguish on clinical presentation and subsequent investigation, there can be enough overlap in the presenting features and on imaging studies that differentiation is sometimes extremely difficult. As this confusion may lead to either major pancreatic resection for benign disease, or rejection of surgery for a potentially curable lesion, all attempts to arrive at a correct diagnosis should be pursued. This article provides an update of investigative techniques in pancreatic disease, and offers an algorithm for the clinical approach to the patient who appears to present with this diagnostic and therapeutic dilemma.
Rapidly Involuting Congenital Hemangioma: Clinical and Histopathologic Features
Authors: Berenguer Beatriz , Mulliken John B. , Enjolras Odile , Boon Lawrence M. , Wassef Michel , Josset Patrice , Burrows Patricia E. , Perez-Atayde Antonio R. , Kozakewich Harry P.W.
Published: March 2004

We define the histopathologic findings and review the clinical and radiologic characteristics of rapidly involuting congenital hemangioma (RICH). The features of RICH are compared to the equally uncommon noninvoluting congenital hemangioma (NICH) and common infantile hemangioma. RICH and NICH had many similarities, such as appearance, location, size, and sex distribution. The obvious differences in behavior served to differentiate RICH, NICH, and common infantile hemangioma. Magnetic resonance imaging (MRI) of the three tumors is quite similar, but some RICH also had areas of inhomogeneity and larger flow voids on MRI and arterial aneurysms on angiography. The histologic appearance of RICH differed from NICH and common infantile hemangioma, but some overlap was noted among the three lesions. RICH was composed of small-to-large lobules of capillaries with moderately plump endothelial cells and pericytes; the lobules were surrounded by abundant fibrous tissue. One-half of the specimens had a central involuting zone(s) characterized by lobular loss, fibrous tissue, and draining channels that were often large and abnormal. Ancillary features commonly found were hemosiderin, thrombosis, cyst formation, focal calcification, and extramedullary hematopoiesis. With one exception, endothelial cells in RICH (as in NICH) did not express glucose transporter-1 protein, as does common infantile hemangioma. One RICH exhibited 50% postnatal involution during the 1st year, stopped regressing, was resected at 18 months, and was histologically indistinguishable from NICH. In addition, several RICH, resected in early infancy, also had some histologic features suggestive of NICH. Furthermore, NICH removed early (2–4 years), showed some histologic findings of RICH or were indistinguishable from RICH. We conclude that RICH, NICH, and common infantile hemangioma have overlapping clinical and pathologic features. These observations support the hypothesis that these vascular tumors may be variations of a single entity ab initio. It is unknown whether the progenitor cell for these uncommon congenital vascular tumors is the same as for common infantile hemangioma.
Mechanical properties of the scapholunate ligament correlate with bone mineral density measurements of the hand
Authors: Johnston James D. , Small Carolyn F. , Bouxsein Mary L. , Pichora David R.
Published: March 2004

The mechanical properties of the scapholunate ligament have been previously examined in small sample sizes, with ultimate load and occasionally stiffness reported. The present study examined 16 scapholunate ligaments in uniaxial extension at two rates and determined stiffness, ultimate load, and stress relaxation properties. Mean stiffness values of 66.4 ± 28.6 N/mm at an elongation rate of 50 mm/min and 94.5 ± 44.4 N/mm at an elongation rate of 100 mm/min were found. Relaxation behavior, determined by the percent load remaining after 100 s, was found to be 68.1 ± 12%. Mean ligament ultimate loads were 357 ± 110 N (n = 8). In eight specimens, failure occurred in bone. Positive correlations were observed between bone mineral density of the hand and ligament stiffness, ligament ultimate load, and bone ultimate load. No correlation was observed between bone mineral density and ligament load relaxation behavior. The results provide a comprehensive understanding of scapholunate ligament biomechanics and demonstrate a relationship between bone and ligament properties. © 2004 Orthopaedic Research Society. Published by Elsevier Ltd. All rights reserved.
The use of a non‐ionic surfactant (P188) to save chondrocytes from necrosis following impact loading of chondral explants
Authors: Phillips Daniel M. , Haut Roger C.
Published: March 2004

While current injury criteria for the automotive industry are based on bone fracture, the majority of knee injuries suffered in collisions each year do not involve fracture of bone. Instead, clinical studies of traumatic joint injury often document early pain and development of chronic diseases, such as osteoarthritis. Previous studies suggest chronic disease can be initiated by cell death that occurs in articular cartilage during mechanical trauma to the joint. In the current investigation early necrosis of chondrocytes was investigated after blunt trauma to chondral explants. A non‐ionic surfactant (P188) was explored as a potential tool for early intervention into the disease process, as this surfactant has been shown to repair damaged membranes in other cell lines. Three groups of adult bovine chondral explants were equilibrated for 48 h in culture media. Two groups were then loaded to 25 MPa in unconfined compression. Half the specimens in each group were incubated in media supplemented with 8 mg/ml P188 immediately after loading, while the other half was returned to standard media. At 1 and 24 h the percentages of live and dead cells in compressed and control groups were determined with a cell viability stain. At 1 h post‐trauma, P188 incubated specimens had a significantly increased percentage of live cells in the superficial zone versus the no‐P188 group. At 24 h the percentages of live cells in all three zones of the P188‐treated explants were significantly greater than in the no treatment group. This study showed that P188 surfactant could help restore the integrity of cell membranes in cartilage damaged by blunt mechanical trauma. With the ability of P188 to “save” chondrocytes from early necrotic death using in vitro chondral explants, its role in prevention of a post‐traumatic osteo‐arthritis in a diarthrodial joint should be further explored using in vivo animal models. © 2004 Orthopaedic Research Society. Published by Elsevier Ltd. All rights reserved.
EXPERIMENTAL ASSESSMENT OF THE IMPACT OF DEFOLIATION ON GROWTH AND PRODUCTION OF WATER-STRESSED MAIZE AND COTTON PLANTS
Authors: YANG Z. , MIDMORE D. J.
Published: March 2004

In this study, different levels of defoliation were imposed on a determinate species (maize) and a relatively indeterminate species (cotton). The aim was to quantify the effects of defoliation on plant growth and production, under either optimum or water-stressed conditions. Under well-watered conditions, 33% defoliation twice (conducted 28 and 35 days after emergence) resulted in a 16% reduction in grain yield of maize while 67% defoliation once (conducted 28 days after emergence) had no significant effect on yield. Under water stress, the grain yields of maize plants with 33% (twice) and 67% defoliation were 13.5% and 25% greater than that of non-defoliated control plants, respectively. For cotton, the reproductive yields (seed and lint) with 33% and 67% defoliation (conducted 43 days after emergence) were reduced, under well-watered conditions, by 28% and 37% of that of the non-defoliated control, respectively. Defoliated cotton plants lost less fruiting forms (squares and young bolls) than non-defoliated plants during water stress. Therefore, under water stress the harvestable product of cotton plants with 67% defoliation was double that of non-defoliated control plants. In non-defoliated cotton plants, a second flush of flowering after release from water-stress permitted further compensatory fruit set and boll harvest. Defoliated plants did not show such levels of compensation. Defoliation significantly reduced water use by maize and cotton. The relative yield advantage of defoliated plants under water-stress conditions can be attributed to defoliation-induced improvement in water status as reflected in measures of photosynthetic rate and stomatal conductance. Under anticipated drought stress, defoliation could be an important management practice to reduce drought-induced yield decrease, but this needs to be tested under field conditions.
EARLY ADOPTION OF THE TROPICAL FORAGE LEGUME ARACHIS PINTOI IN HUETAR NORTE, COSTA RICA
Authors: WÜNSCHER T. , SCHULTZE-KRAFT R. , PETERS M. , RIVAS L.
Published: March 2004

The legume Arachis pintoi has a number of characteristics which enable it to make a valuable contribution to the development of sustainable and productive pastures in the tropics. It was introduced to Costa Rica for this reason, in 1987. The objective of this study was to analyse the adoption of A. pintoi as a forage legume in Huetar Norte, a region in the north of Costa Rica. The adoption process was analysed to identify the contributory factors and to make recommendations for measures which could be taken to promote the process. To collect the data, 115 randomly selected livestock holders and an additional 34 farmers known to have planted A. pintoi were interviewed. Farmers see improved pastures to be the most important technology to enhance forage and cattle production. It was confirmed that A. pintoi is a potential improved pasture alternative. Although A. pintoi was well known., the adoption rate was low. Lack of availability of seed, technical assistance and information about the use and management of A. pintoi hinder adoption. Difficulties in establishment and maintenance were also recorded.
Erzählen und Analysieren - Kreatives Schreiben für Therapie und Fiktion
Authors: Buslau Oliver
Published: March 2004

Zusammenfassung. Therapeutisches und literarisches Schreiben besitzen Berührungspunkte - zumal das therapeutische Schreiben ein Einstieg zum literarischen Schreiben sein kann. In den amerikanischen Ausbildungsmethoden sind diese Berührungspunkte zu erkennen. Möglichkeiten zur Grenzüberschreitung der beiden Schreib-Bereiche finden sich vor allem bei James N. Frey und Christopher Vogler - bei Frey im Rahmen der Figurenentwicklung, bei Vogler im Konzept der so genannten “Heldenreise“.
Tritium budget of the South Atlantic
Authors: Butzin Martin , Roether Wolfgang
Published: March 2004

Oceanic tritium inventories of the South Atlantic are deduced from tritium observations and are compared with estimated tritium deliveries. In 1993 the total water column tritium inventory between 0°S and 50°S based on World Ocean Circulation Experiment data amounted to 2.88 × 1016 TU 81 m3 (i.e., tritium units decay corrected to 1981; 3.44 × 1018 Bq, uncertainty ±10%) with 80% residing in the upper 800 m. This is about 10% higher than observed during the South Atlantic Ventilation Experiment program in 1987–1989 but twice the amount reported for the Geochemical Ocean Sections Study survey 1972–1973. Maximum tritium water column contents are found in the subtropics, where in 1993 the bomb signal penetrated to approximately 1000 m depth and where the decay‐corrected surface water tritium concentrations were highest and still slowly increasing. The total tritium inventories agree with integrated tritium deliveries that were estimated building upon previously published global input functions, adjusted to the conditions of the South Atlantic. The agreement supports the delivery estimates, which by themselves have considerable uncertainty margins. Tritium surface water time histories of the South Atlantic are inferred for the period 1952–1995 by combining the available observations and atmospheric tritium depositions within a simple scheme. The estimated deliveries (effective uncertainty ±30%) and surface water tritium concentrations (±15%) can serve as boundary conditions in water mass dating and for employing tritium in ocean general circulation models.
Global shape of the magnetotail current sheet as derived from Geotail and Polar data
Authors: Tsyganenko N. A. , Fairfield D. H.
Published: March 2004

An analytical approximation is developed for the shape of the nightside tail current sheet, representing it as a function of the Earth's dipole tilt angle, solar wind ram pressure, and the interplanetary magnetic field (IMF). The model is based on 5‐min average magnetometer data of the Geotail and Polar spacecraft, spanning the periods 1994–2002, and 1999–2001, respectively. All the magnetospheric data were tagged by concurrent values of the solar wind dynamic pressure and IMF By and Bz components, averaged over 30‐min intervals immediately preceding the magnetospheric observations. Warping and twisting parameters were calculated by minimizing the number of mismatches between the observed and predicted orientation of the magnetic field on both sides of the model current sheet. The model is valid within the nightside magnetosphere in the range of tailward distances −50 RE ≤ XGSM ≤ 0. Variations of the solar wind pressure P change the shape of the deformed current sheet in such a way that an increase of P results in a decrease of the magnetotail “hinging distance” RH, but increases the magnitude of its transverse warping. The IMF Bz component affects the magnitude of the seasonal/diurnal motion of the current sheet in the north‐south direction, and it also controls the degree of the IMF By‐related twisting, which becomes much larger during the periods with northward IMF Bz.
Parameterization of ocean self‐attraction and loading in numerical models of the ocean circulation
Authors: Stepanov Vladimir N. , Hughes Christopher W.
Published: March 2004

The effect of ocean self‐attraction and loading (SAL) is considered in a global, barotropic ocean model forced by atmospheric wind stress, atmospheric pressure, and tidal forcing. Periods shorter than 7 days are considered. The model is integrated with a proper calculation of these effects in terms of a (very expensive) Green's function convolution at each time step. SAL effects produce a perturbation of typically about 10% of the computed ocean bottom pressure, but much more in places, for both tidal and atmospherically forced motions. An investigation into simple parameterizations of these effects by means of a term proportional to local bottom pressure reveals the following results: For tides, the best coefficient is systematically dependent on depth, ranging from less than 0.08 in shallow water to about 0.12 in the deepest water, and incorporating this effect improves the parameterization. For atmospherically forced motions, there is still some effect of depth but more an effect of latitude (increasingly so for longer periods), regional variation is greater, and correlation between the SAL effect and bottom pressure is weaker. Parameterization with a constant coefficient of 0.1 reduces errors due to failing to include SAL by about 30%. To do better than this, a proper scale‐dependent representation of SAL must be used.
Variations of 0.7–6.0 MeV electrons at geosynchronous orbit as a function of solar wind
Authors: Li Xinlin
Published: March 2004

The variations of MeV electron flux at geosynchronous orbit are predictable based on solar wind measurements. Using a model based on the standard radial diffusion equation applied for the years 1995–1999, a prediction efficiency of 64.4% and a linear correlation of 0.81 were achieved for the logarithm of average daily flux of 0.7–1.8 MeV electrons. The same model with different parameters gave a prediction efficiency of 70.2% and 72.4% and a linear correlation of 0.84 and 0.85, respectively, for 1.8–3.5 MeV and 3.5–6.0 MeV electrons during the same time period. The radial diffusion coefficient in the model is a function of location, solar wind velocity, interplanetary magnetic field, season, and solar cycle. The average lifetime of the electrons is a function of the radial distance and solar cycle. The radial diffusion equation is solved with given boundary conditions. These results suggest that MeV electrons at geosynchronous orbit, extending over a wide energy range, have a systematic response to the solar wind variations. This model has been updated and is making real‐time forecasts of daily averaged >2 MeV electron fluxes at geosynchronous orbit.
Crystal structure of the PsbP protein of photosystem II from Nicotiana tabacum
Authors: Ifuku Kentaro , Nakatsu Toru , Kato Hiroaki , Sato Fumihiko
Published: March 2004

PsbP is a membrane‐extrinsic subunit of the water‐oxidizing complex photosystem II (PS II). The evolutionary origin of PsbP has long been a mystery because it specifically exists in higher plants and green algae but not in cyanobacteria. We report here the crystal structure of PsbP from Nicotiana tabacum at a resolution of 1.6 Å. Its structure is mainly composed of β‐sheet, and is not similar to any structures in cyanobacterial PS II. However, the electrostatic surface potential of PsbP is similar to that of cyanobacterial PsbV (cyt c550), which has a function similar to PsbP. A structural homology search with the DALI algorithm indicated that the folding of PsbP is very similar to that of Mog1p, a regulatory protein for the nuclear transport of Ran GTPase. The structure of PsbP provides insight into its novel function in GTP‐regulated metabolism in PS II.
Detection of circulating antibodies against malondialdehyde-acetaldehyde adducts in patients with alcohol-induced liver disease
Authors: Rolla Roberta , Vay Daria , Mottaran Elisa , Parodi Monica , Traverso Nicola , Aricó Sarino , Sartori Massimo , Bellomo Giorgio , Klassen Lynell W. , Thiele Geoffrey M. , Tuma Dean J. , Albano Emanuele
Published: March 2004

Acetaldehyde and malonildialdehyde can form hybrid protein adducts, named MAA adducts that have strong immunogenic properties. The formation of MAA adducts in the liver of chronic alcohol-fed rats is associated with the development of circulating antibodies that specifically recognized these adducts. The aim of this study was to examine whether MAA adducts might participate in the immune response associated with human alcohol-induced liver disease. Circulating antibodies against MAA adducts were evaluated in 50 patients with alcohol-induced hepatitis or cirrhosis, in 40 patients with non-alcohol-induced liver disease, in 15 heavy drinkers without liver damage and in 40 healthy controls by enzyme-linked immunosorbent assays (ELISA). Immunoglobulin G (IgG) reacting with MAA-modified proteins were significantly increased in the patients with alcohol-induced cirrhosis or hepatitis. The individual levels of anti-MAA IgG in those patients were associated with the severity of liver damage. Anti-MAA antibodies were also positively correlated with the levels of IgG recognizing epitopes generated by acetaldehyde and malonildialdehyde. However, competitive inhibition experiments indicated that the anti-MAA antibodies were unrelated to those against acetaldehyde- or malonildialdehyde-derived antigens and mainly recognized a specific, cyclic MAA epitope. Some degree of immune reactivity towards MAA adducts was also observed in patients with non-alcohol-induced liver injury. However, competitive ELISA showed that the antigens recognized by these sera were not the cyclic MAA adducts. Altogether, these results showed the formation of MAA antigens during alcohol-induced liver disease and suggest their possible contribution to the development of immunologic reactions associated with alcohol-related liver damage.
Detection of adenovirus and initiation of apoptosis in hepatocellular carcinoma cells after ad- p53 treatment
Authors: Mitry Ragai R. , Sarraf Catherine E. , Havlík Roman , Habib Nagy A.
Published: March 2004

Transcription of the p53 gene can regulate progression of apoptosis in a wide variety of tissues. Three categories of human hepatocyte culture have been used to show the initiation of apoptosis after treatment with p53-bearing adenovirus. Chang liver cells are derived from normal liver tissue and express native p53, whereas hepatocellular carcinoma (HCC)-derived cell lines were Hep3B (p53-deleted) and PLC/PRF/5 (p53-mutant). Cultures were infected with Ad-p53 (15 particles per cell; 36 hours), and after treatment, morphological changes in all cell categories were observed by electron microscopy. Infection was evident in the cytoplasm of all treated cell types: after entry across the plasma membrane viruses translocated and came to rest surrounding and adjacent to nuclei, cytoplasm proximal to nuclear membranes became dense with virus- and membrane-derived debris, but intact viruses did not enter nuclei. Apoptosis, recognized morphologically by characteristic chromatin and cytoplasmic condensation, occurred more frequently in HCC-derived cells, and the ultimate fate of apoptotic bodies was phagocytosis and degradation by neighboring cells.
Fractional allelic loss in non-end-stage cirrhosis: Correlations with hepatocellular carcinoma development during follow-up
Authors: Roncalli Massimo , Bianchi Paolo , Grimaldi Giorgia Ceva , Ricci Daniele , Laghi Luigi , Maggioni Marco , Opocher Enrico , Borzio Mauro , Coggi Guido
Published: March 2004

Hepatocellular carcinoma (HCC) is usually preceded by cirrhosis whose genetic background is still poorly understood. The aim of this study was to evaluate, in non-end-stage cirrhosis, the fractional allelic loss (FAL) at loci mostly reported to be altered in HCC and the microsatellite instability (MSI). Twenty cases of cirrhosis were retrospectively selected. Eleven had developed an HCC during the follow-up (HCC-prone group), while 9 remained HCC-free (HCC-free group). Microdissected hepatocellular cirrhotic nodules from basal liver biopsies, were studied at 20 loci (on the chromosomal arms 1p and 1q, 3p, 4q, 6q, 7q, 8p, 13q, and 18q) and with the mononucleotide repeats BAT26andTGFbIIR. Genetic changes were detected in both groups. Overall, the FAL index was statistically increased in the HCC-prone group (0.213) as compared to the HCC-free group (0.094; P = .044). Allelic loss at chromosomal arms 1p, 4q, 13q, 18q, and concurrent losses at more than 3 loci were confined to the HCC-prone group. In both groups, MSI was never ascertained using BAT26and TGFbIIR. In conclusion, an increased FAL index and the lack of MSI characterize the non-end-stage cirrhosis of patients undergoing HCC during follow-up. These data emphasize the role of early clonal changes in chronic liver disease, and their potential predictive significance for clinical use.
Intensive expansion of natural killer T cells in the early phase of hepatocyte regeneration after partial hepatectomy in mice and its association with sympathetic nerve activation
Authors: Minagawa Masahiro , Oya Hiroshi , Yamamoto Satoshi , Shimizu Takao , Bannai Makoto , Kawamura Hiroki , Hatakeyama Katsuyoshi , Abo Toru
Published: March 2004

When C57BL/6 mice were partially hepatectomized (PHx), severe lymphocytosis was induced in the liver in the early phase of hepatocyte regeneration (4 to 12 hours after PHx). A major lymphocyte subset expanding in this organ was estimated to be natural killer 1.1+ (NK1.1+) intermediate CD3 (CD3int) cells (i.e., NKT cells). CD3int cells are extrathymic T cells generated in situ in the liver. These changes were suppressed when mice with PHx were pretreated with a β-adrenergicD antagonist (i.e., β-blocker), propranolol (PPL). This might have been caused by sympathetic nerve stimulation during hepatocyte regeneration. An α-blocker showed a similar effect, although the magnitude of suppression was lower than that of the β-blocker. We previously showed that NK and NKT cells express surface β-adrenergic receptors and are activated in number by sympathetic nerve stimulation. In the present study, NK cytotoxicity mediated by liver lymphocytes obtained from mice with PHx decreased, whereas NKT cytotoxicity against syngeneic thymocytes increased. Purified CD3int cells were also found to be able to mediate NKT cytotoxicity against regenerating hepatocytes. These results suggest that sympathetic nerve stimulation after PHx results in subsequent activation of NKT cells and that these NKT cells might be associated with immunologic surveillance during hepatocyte regeneration.
Effect of maternal cholestasis on bile acid transfer across the rat placenta-maternal liver tandem
Authors: Macias Rocio I. , Pascual Maria J. , Bravo Ana , Alcalde Maria P. , Larena Monica G. , St.-Pierre Marie V. , Serrano Maria A. , Marin Jose J.G.
Published: March 2004

Cholestasis of pregnancy induces alterations in bile acid transport by human trophoblast plasma membrane (TPM) vesicles. We investigated whether maternal cholestasis affects the overall ability of the rat placenta to carry out vectorial bile acid transfer from the fetus to the mother. Complete obstructive cholestasis (OCP) was maintained during the last week of pregnancy and released at term (day 21), before experiments were performed. In situ single-pass perfusion of one placenta per rat with 250 nmol [14C]glycocholic acid (GC) revealed an impaired uptake in OCP rats (2.28 vs. 5.53 nmol in control rats). Approximately 100% of GC taken up by control placentas was secreted in maternal bile over 120 minutes (5.38 nmol), whereas this was only 61% (1.40 nmol) of the GC taken up by OCP placentas. When 5 nmol GC was administered through the jugular vein no significant difference between both groups in total GC bile output was found. The efficiency (V
max /K
M) of adenosine triphosphate (ATP)-dependent GC transport by vesicles from the maternal side of TPM was decreased (−41%) in OCP. Moreover, histological examination of the placentas suggested a reduction in the amount of functional trophoblast in the OCP group. This was consistent with a lower antipyrine diffusion across the placenta in these animals. In sum, our results indicate that maternal cholestasis affects the ability of the placenta to efficiently carry out bile acid transfer from fetal to maternal blood. Changes in both the structure and the functionality of the chorionic tissue may account for this impairment.
p27Kip1 expression in normal epithelia, precancerous lesions, and carcinomas of the gallbladder: Association with cancer progression and prognosis
Authors: Hui Ai-Min , Li Xin , Shi Ya-Zhou , Torzilli Guido , Takayama Tadatoshi , Makuuchi Masatoshi
Published: March 2004

p27Kip1 is a cyclin-dependent kinase inhibitor that negatively regulates cell proliferation. This study was designed to evaluate the roles of p27Kip1 in gallbladder carcinogenesis and the prognostic value of p27Kip1 in patients with gallbladder carcinoma. p27Kip1 expression was examined immunohistochemically in surgically resected specimens of 8 normal epithelia, 8 adenomyomatosis lesions, 6 precancerous adenomas, and 37 carcinomas of the gallbladder. Decreased p27Kip1 expression (<50% nuclear staining) was observed in 16 of the 37 (43%) gallbladder carcinomas, but not in any specimen of normal epithelium, adenomyomatosis, or adenoma. The fact that all of the adenomas showed normal p27Kip1 expression suggests that decreased p27Kip1 expression is probably not an early event in gallbladder carcinogenesis. Decreased p27Kip1 expression was significantly associated with less marked tumor cell differentiation (P = .017), lymphatic invasion (P = .046), lymph node metastasis (P = .007), and advanced TNM stage (stage IV vs. stage I, P = .026; stage IV vs. stage II, P = .005). This suggests that down-regulation of p27Kip1 expression is a late event in gallbladder carcinogenesis, possibly promoting tumor progression and metastasis. Kaplan-Meier curves showed that decreased p27Kip1 expression was significantly associated with shorter overall survival (P = .001) in patients with gallbladder carcinomas who had undergone radical surgery. Cox’s proportional hazards model revealed decreased p27Kip1 expression to be an independent predictor for death (P = .034; risk ratio, 3.9; 95% confidence interval, 1.1-13.7). In conclusion, decreased p27Kip1 expression significantly correlates with tumor progression and predicts poor prognosis in gallbladder carcinomas.
Hypogonadism precedes liver feminization in chronic alcohol-fed male rats
Authors: Tadic Stasa D. , Elm Mary S. , Subbotin Vladimir M. , Eagon Patricia K.
Published: March 2004

Men who chronically abuse alcohol may display a spectrum of endocrine abnormalities including hypogonadism and feminization, with elevated serum estradiol and low serum testosterone. We examined factors that may result in disruption of hepatic sex hormone homeostasis in alcohol-fed male rats and possible consequences of such changes. Rats were fed alcohol-containing or isocaloric diets for 30, 60, and 90 days. In alcohol-fed rats, serum testosterone levels and hepatic activity of 2 androgen-dependent estrogen metabolizing enzymes were reduced (P < .05) at all times, as was activity of androgen receptor. There was also a significant early and progressive decrease in testes/body ratio in alcohol-fed rats. Compared with this early decrease in testosterone-related parameters, there was a significant increase in serum estrogen levels (at 30 and 90 days, 132% and 168% of control values, respectively). An increase in serum ceruloplasmin, an estrogen-responsive liver protein, was apparent at 60 and 90 days, but not at 30 days of alcohol exposure, suggesting that hypogonadism precedes liver feminization. Hepatic estrogen receptor activity was decreased in alcohol-fed rats at 60 and 90 days, the latter despite elevated serum estrogen levels. Hepatic aromatase was slightly increased in alcohol-fed rats, an elevation probably not sufficient to account for observed increases in serum estrogen. Taken together, these data suggest that (1) alcohol induces profound reduction of serum testosterone, resulting in loss of androgen-regulated hepatic functions such as estrogen-metabolizing enzyme activity and activity of androgen receptors; and (2) such alcohol-induced hypogonadism precedes changes in hepatic sex hormone homeostasis and subsequent feminization.
Molecular mechanisms of tumor necrosis factor α-stimulated leukocyte recruitment into the murine hepatic circulation
Authors: Fox-Robichaud Alison , Kubes Paul
Published: March 2004

To date, much of the adhesion work in the liver has been restricted to sinusoids and postsinusoidal venules. However, selectins have been localized on the portal (presinusoidal) venules and these vessels have been shown to be important in metastasis of tumors. The purpose of this study was to characterize the leukocyte-endothelial interactions within the 3 compartments of the hepatic microvasculature under baseline conditions and in response to tumor necrosis factor α (TNF-α). Mice deficient in P-selectin or both E- and P-selectin were compared with wild-type (C57Bl/6, wild type) mice. Animals were injected with murine TNF-α (15 μg/kg intraperitoneally [IP]) and the liver was examined by fluorescence intravital microscopy 4 hours later. Under baseline conditions, leukocyte flux in the portal venules was 1.42 ± 0.42 cells/min. Leukocyte flux in the portal venules of wild-type mice increased 8-fold in response to 4 hours of TNF-α stimulation. This was reduced by 50% in the P-selectin-deficient mice but was not reduced further by either the addition of an E-selectin antibody (9A9, 100 μg intravenously [IV]) to these mice or in mice deficient in both E- and P-selectin. In P-selectin-deficient mice, the addition of an antibody against α4-integrin (R1-2, 75 μg IP) reduced rolling to baseline. But in the E- and P-double-selectin-deficient mice the addition of an antibody against L-selectin (Mel 14, 3 μg/kg IV) had no effect on TNF-α-induced recruitment. Similar responses were seen in the central venules, however, in the sinusoids the increased number of stationary leukocytes seen in response to 4 hours of TNF-α stimulation in the wild-type mice was not reduced in P-selectin-deficient mice with or without the α4-integrin antibody. These data suggest that leukocytes can use α4-integrin independent of the selectins in the venules. Within the sinusoids, however, inhibition of E-selectin, P-selectin, and α4-integrin was insufficient to reduce leukocyte recruitment.
Intragraft localization of activated nuclear factor κB in recurrent hepatitis C virus disease following liver transplantation
Authors: Gaweco Anderson S. , Wiesner Russell H. , Porayko Michael , Rustgi Vinod K. , Yong Sherri , Hamdani Raza , Harig James , Chejfec Gregorio , McClatchey Kenneth D. , Van Thiel David H.
Published: March 2004

Nuclear factor κB (NF-κB) is activated during viral infection and is central to the regulation of host immune responses. The NF-κB activation status and its morphological sources were assessed by immunohistochemistry in allograft biopsy specimens of orthotopic liver transplantation patients with recurrent hepatitis C virus (HCV). Hepatocellular NF-κB immunostaining was detected in HCV cases compared with controls (nontransplant: P < .001; transplant: P = .006), which correlated with the number of NF-κB positive hepatocytes (P = .007) and contrasted to the absent to weak staining of controls (nontransplant: P = .001; transplant: P = .009). Enhanced NF-κB staining of cytokeratin 19-positive bile ducts and proliferating ductules in the HCV group was in contrast to controls. Intense NF-κB immunoreactivity was detected in CD68-positive Kupffer cells and macrophages of all HCV specimens compared with a few controls (nontransplant: P < .001; transplant: P = .001) and contrasted to the weak staining of controls (nontransplant: P < .001; transplant: P = .001). NF-κB-positive immunoreactivity correlated with the number of T cell receptor (TCR) α/β-positive lymphocytes (P < .001), which was not observed in controls. In those HCV cases showing evidence of necroinflammatory activity (grade) and individual features of portal inflammation, periportal inflammation/piecemeal necrosis, lobular inflammation, and fibrosis (stage), higher NF-κB staining intensity scores within bile ducts, proliferating ductules, hepatocytes (piecemeal necrosis: P = .016; stage: P = .030), and lymphocytes (stage: P = .044) and increased number of NF-κB-positive cells within bile ducts, proliferating ductules (grade, lobular inflammation, piecemeal necrosis, stage: P = .022), hepatocytes, and lymphocytes were observed. Increased staining intensity and frequency of NF-κB-positive cells were similarly observed in HCV-positive allografts obtained from patients under tacrolimus- compared with cyclosporine-based immunosuppression. These data implicate an immunoregulatory role of intragraft NF-κB activation in the pathogenesis and progression of posttransplantation HCV disease recurrence.
Acute Exacerbation of Chronic Hepatitis B Virus Infection After Withdrawal of Lamivudine Therapy
Authors: Honkoop Pieter , de Man Robert A. , Niesters Hubert G.M. , Zondervan Pieter E. , Schalm Solko W.
Published: March 2004

Acute exacerbations of chronic hepatitis B virus (HBV) infection occur after withdrawal of lamivudine therapy in approximately 16% of patients and are considered of little clinical significance. We observed “lamivudine withdrawal hepatitis” accompanied by jaundice and incipient liver failure, but also followed by complete recovery and viral clearance. To investigate the incidence, severity, timing, and virologic characteristics of “lamivudine withdrawal hepatitis” we monitored 41 patients for at least 6 months after discontinuation of nucleoside analogue therapy. The incidence of hepatitis flares was estimated to be 7 of 41 (17%); in 2 of 41 cases (5%), hepatitis flares were associated with jaundice and incipient liver failure. A noticeable feature of the “lamivudine withdrawal hepatitis” flares were the high HBV-DNA levels at the time of the alanine transaminase (ALT) peak. All were wild-type HBV, even the one that emerged from a lamivudine-resistant strain during therapy. To minimize the risk of liver failure and to enhance the elimination of HBV following flares, lamivudine therapy was reinstituted in an icteric patient. Clinical and biochemical remission ensued, followed by loss of HBV DNA and hepatitis B e antigen (HBeAg) seroconversion. Such a virologic response did not occur in 5 other patients with a nonicteric “lamivudine withdrawal hepatitis,” who were not retreated with lamivudine. Hepatitis after withdrawal of lamivudine resembles acute hepatitis B with a predominance of anicteric flares within a time frame of 6 months. Active management of hepatitis flares following withdrawal of nucleoside analogue therapy should be investigated further.
The Impact of Interferon Gamma Receptor Expression on the Mechanism of Escape From Host Immune Surveillance in Hepatocellular Carcinoma
Authors: Nagao Mitsuo , Nakajima Yoshiyuki , Kanehiro Hiromichi , Hisanaga Michiyoshi , Aomatsu Yukio , Ko Saiho , Tatekawa Yukihiro , Ikeda Naoya , Kanokogi Hideki , Urizono Yasuyuki , Kobayashi Tsunehiro , Shibaji Takamune , Kanamura Tetsuhiro , Ogawa Sanehito , Nakano Hiroshige
Published: March 2004

Interferon gamma (IFN-γ) plays an important role in host defense mechanism and participates in the progression of chronic liver disease. IFN-γ exerts its pleiotrophic effects by transcriptional regulation of expression of numerous genes, such as major histocompatibility complex (MHC) class I and Fas, through interaction with IFN-γ receptor (IFN-γ-R). Although hepatocytes in normal liver express weak or no IFN-γ-R, those in acute and chronic liver disease up-regulate its expression. A study using IFN-γ-R α-chain knock-out mice revealed the actions of IFN-γ on tumor cells as an extrinsic tumor-suppressor mechanism. However, it is unclear whether or how hepatocellular carcinoma (HCC) blocks the signal transduction of IFN-γ to evade host immune surveillance. We examined the expression of IFN-γ-R and IFN-γ-inducible genes in 44 cases with HCC using real-time reverse-transcriptase polymerase chain reaction (RT-PCR) and immunohistochemistry. In noncancerous liver tissues (n = 38), IFN-γ-R expression on the cell surface was up-regulated in 27 cases. In IFN-γ-R-negative cases (n = 15), tumor size was larger (P = .032), serum α-fetoprotein (AFP) level was higher (P = .001), intrahepatic and extrahepatic metastasis was more common (P = .044 and .013, respectively), and Ki-67 labeling index (LI) was higher (P = .041), compared with IFN-γ-R-positive cases. Accordingly, the evasion mechanism may play an important role in progression, especially metastasis, in HCC. The significant correlation between the status of IFN-γ-R and the expression of Fas and MHC implies that the loss of IFN-γ-R might contribute to the mechanism of escape from host immune rejection in HCC.