bluuebunny/crossref_metadata_2025 huggingface dataset:
A new supercontinent self-destruct mechanism: evidence from the Late Triassic–Early Jurassic
Authors: VAUGHAN ALAN P.M. , STOREY BRYAN C.
Published: February 2007

We present a new conceptual model where supercontinents, by focusing subduction on narrow areas of the 670 km mantle discontinuity, trigger superplume events and initiate their own fragmentation. This supercontinent-triggered superplume mechanism for continental break-up is examined in light of the Mesozoic fragmentation of Pangaea–Gondwana. We summarize the evidence for a superplume event that occurred between 227 and 183 Ma ago, during the Late Triassic–Early Jurassic break-up of Pangaea–Gondwana. The evidence reviewed includes flood magmatism, kimberlite emplacement, plate reorganization and tectonism (including ophiolite obduction events), reversal rate frequency of the geomagnetic field, marine anoxia, deposition of carbon-rich sediments, including oil source rocks and coal, the carbon isotope record, major mass extinctions, and global sea levels. This Late Triassic–Early Jurassic superplume event was comparable in scale with those in the late Proterozoic (
c
. 800 Ma) and during Cretaceous times (
c
. 120–80 Ma). Similar to the mid-Cretaceous event, an extended phase of plume magmatism is implicated, with two oceanic and three continental large igneous provinces being emplaced.
Geochemistry and tectonic setting of mafic rocks in western Dronning Maud Land, East Antarctica: implications for the geodynamic evolution of the Proterozoic Maud Belt
Authors: Grosch Eugene G. , Bisnath Avinash , Frimmel Hartwig E. , Board Warwick S.
Published: February 2007

On the basis of new bulk major and trace element (including REE) as well as Sm–Nd and Rb–Sr isotope data, used in conjunction with available geochronological data, a post-tectonic mafic igneous province and four groups of pre- to syntectonic amphibolite are distinguished in the polymetamorphic Maud Belt of western Dronning Maud Land, East Antarctica. Protoliths of the Group 1 amphibolites are interpreted as volcanic arc mafic intrusions with Archaean to Palaeoproterozoic Nd model ages and depletion in Nb and Ta. Isotopic and lithogeochemical characteristics of this earliest group of amphibolite indicate that the Maud Belt was once an active continental volcanic arc. The most likely position of this arc, for which a late Mesoproterozoic age (
c
. 1140 Ma) is indicated by available U–Pb single-zircon age data, was on the southeastern margin of the Kaapvaal–Grunehogna Craton. The protoliths of Group 2 amphibolites are attributed to the 1110 Ma Borgmassivet–Umkondo thermal event on the basis of comparable Nd model ages and trace element distributions. Group 3 amphibolite protoliths are characterized by mid-ocean ridge basalt-type REE patterns and low Th/Yb ratios, and they are related to Neoproterozoic extension. Group 4 amphibolite protoliths are distinguished by high Dy/Yb ratios and are attributed to a phase of syntectonic Pan-African magmatism as indicated by Rb–Sr isotope data.
The Orange River, southern Africa: an extreme example of a wave-dominated sediment dispersal system in the South Atlantic Ocean
Authors: Bluck B.J. , Ward J.D. , Cartwright J. , Swart Roger
Published: February 2007

Sediments delivered to the South Atlantic Ocean by the Orange River are fractionated and dispersed northwards and westwards by a vigorous longshore drift system and a number of ocean currents. Gravels are accreted to the coastline for a distance >300 km north from the Orange River mouth. Sands are transported alongshore for >700 km but are, in places along this transport path, returned onshore by coastal winds to form the main Namib Sand Sea and other smaller dune fields. Mud is more widely dispersed westwards, northwards and southwards, probably by slow-moving, ocean-scale currents into basins on the shelf and onto the continental shelf edge. This dispersal system, operating since at least Eocene times, is believed to have originated during a time when there was a Late Cretaceous–Early Cenozoic uplift of southern Africa, which resulted in: (1) intensification of the existing southerly wind system; (2) incision of the Orange River, which, coupled with a shift in climate, resulted in a coarsening of its sediment load delivered to the coast; (3) a broad, weakly subsiding or mildly uplifting inner continental shelf with little accommodation space for the sediment load of the incising Orange River.
Tectonometamorphic evolution of high-pressure rocks from the island of Amorgos (Central Aegean, Greece)
Authors: Rosenbaum Gideon , Ring Uwe , Kühn Alexander
Published: February 2007

Structural and metamorphic data from the island of Amorgos (central Aegean Sea) show evidence for the existence of two distinct high-pressure units, the Metabasite Unit and the Basal Conglomerate Unit. These are exposed at the base of a thick marble sequence and overlying flysch deposits. The Metabasite Unit is characterized by a mineral assemblage of blue amphibole, garnet and clinopyroxene, indicating
P
–
T
conditions of 500–600 °C and >13 kbar. It is juxtaposed below carpholite-bearing metaconglomerates and quartz-rich micaschists of the Basal Conglomerate Unit, for which metamorphic conditions of 300–450 °C and 10–14 kbar are estimated. The contact between the two units is interpreted as a low-angle detachment fault that accommodated top-to-the-NW sense of motion. The Amorgos succession above the Basal Conglomerate Unit collectively resembles the stratigraphy of external units in the Hellenides and could possibly be correlated with the so-called ‘Basal Unit’, which crops out in a number of tectonic windows throughout the Aegean Sea. This means that the Metabasite Unit in Amorgos could possibly represent the lowermost structural unit in the central Aegean Sea.
The first Pacific record of the Late Aptian warming event
Authors: Takashima Reishi , Sano Shin-ichi , Iba Yasuhiro , Nishi Hiroshi
Published: February 2007

Carbonate platforms consisting of hermatypic coral, rudists and larger foraminifers formed along the margin of the NE Japanese islands during the mid-Late Aptian. The geographical northern limit of the carbonate platforms extended to
c
. 36°N at that time, which is the highest latitude for coral and/or rudist formation in the North Pacific region. This geographical extension of the carbonate platform in the NW Pacific indicates extreme climatic warmth in the mid-latitudes and strong poleward heat transport systems. Contemporaneous warming has been detected in European and Australian regions, as represented by the migration of Tethyan fauna toward the boreal realm and the positive excursion of δ
13
C and negative excursion of δ
18
O in deep-sea carbonates. Our new constraint on the northern limit of ‘reef’ growth reinforces the view that an interval of greenhouse-like warmth punctuated the Late Aptian climate.
Late Neoproterozoic to Early Palaeozoic palaoegeography of the Holy Cross Mountains (Central Europe): an integrated approach
Authors: Nawrocki J. , DunlAp J. , Pecskay Z. , Krzemiński L. , Żylińska A. , Fanning M. , Kozłowski W. , Salwa S. , Szczepanik Z. , Trela W.
Published: February 2007

Study of geochemistry, examination of isotope ages of detrital minerals, palaeomagnetic analysis, and a study of the trilobites were performed to provide constraints on the palaeogeographical position of the Holy Cross Mountains in Late Ediacaran–Early Palaeozoic time. The geochemical results indicate an active continental margin or continental island arc provenance of the Ediacaran sediments. Sediments from a passive continental margin were deposited here during the Cambrian and Ordovician. The palaeomagnetic pole isolated from Cambrian rocks of the Małopolska region of the Holy Cross Mountains corresponds to the Cambrian segment of the Baltic apparent polar wander path. Isotope age estimations indicate that Cambrian sediments of the Małopolska region contain detritus not only from a latest Neoproterozoic source but also from sources with ages of
c
. 0.8–0.9 Ga, 1.5 Ga and 1.8 Ga. The Małopolska, Brunosilesia, Dobrugea and Moesia terranes, which originally developed near the present southern edge of Baltica and were partly involved in the Cadomian orogen, were dextrally relocated along its Trans-European Suture Zone margin. The first stage of this movement took place as early as latest Ediacaran time, while Baltica rotated anticlockwise. Anticlockwise rotation of Baltica at the Cambrian–Ordovician boundary implies further dextral movement of the Małopolska block.
Relationships between right-lateral shear along the Karakoram fault and metamorphism, magmatism, exhumation and uplift: evidence from the K2–Gasherbrum–Pangong ranges, north Pakistan and Ladakh
Authors: SEARLE MICHAEL P. , PHILLIPS RICHARD J.
Published: February 2007

The Karakoram fault is a major NW–SE-aligned dextral strike-slip fault that has accommodated minor extrusion of thickened Tibetan crust since the Mid-Miocene. Controversy exists as to whether the fault is lithospheric in scale, resulting in synkinematic metamorphism and granite melting, or whether it is an upper crustal fault cutting through earlier metamorphic and granitic rocks. Structural, metamorphic and geochronological data from the Karakoram fault show that: (1) metamorphism and granite genesis occurred prior to strike-slip shearing, meaning that U–Pb zircon and monazite ages from deformed granites cannot be used as proxies for dating strike-slip shearing, only as a maximum age constraint on initiation of ductile shearing; (2) sheared Miocene leucogranites along the fault are equivalent to the Baltoro granite batholith, offset 40–150 km along the fault, and show a strain gradient from high ductile strain to undeformed away from the fault; (3)
40
Ar/
39
Ar and fission-track ages of K2 orthogneisses and Gasherbrum diorite show that rocks adjacent to the fault cooled during Cretaceous to mid-Tertiary time, and were not reset during shearing, indicating that shear heating was not important; (4) the Gasherbrum diorite, adjacent to the fault, has never been at depths greater than 6 km since the early Cretaceous and less than 3 km of material has been eroded off since then. We conclude that the Karakoram fault has had no significant influence on regional metamorphism or melting, at least at levels exposed today, and is restricted to the upper–middle crust.
Cybertectonic Earth and Gaia's weak hand: sedimentary geology, sediment cycling and the Earth system
Authors: Leeder Mike
Published: February 2007

Tectonics, climate and sea level are dominant controls on the nature and distribution of sedimentary environments. By inverse logic, recognition of influences on sedimentation from the stratigraphic record as a result of perturbations in these variables leads to clarification of past environmental and structural change. The succession of sedimentary environments in time and place is determined by a wider combination of variables; namely, sediment flux, biological evolution, atmosphere and water body productivity and chemistry. The feedbacks and interrelationships between all variables cause the complexity seen in sedimentation processes over geological time. The processes of global tectonics that cause widespread mountain belt and continental plateau uplift have produced numerous ‘severe’ events during Earth history: these often random workings-out of the plate tectonic cycle define the state of ‘Cybertectonic Earth’ (from
cyber
, after the Greek
kubernan
: to steer or govern). This has worked within a usually zonally arranged series of climatic belts and within the framework provided by biological evolution. At certain times in the geological past, a combination of factors arose as a response to continental uplift and have acted to cause certain Earth surface conditions and variables (notably mean global surface temperature, atmospheric
p
CO
2
,
p
O
2
) to have varied by very large amounts (×2–×10) compared with present values. These large fluctuations, such as those responsible for the Neoproterozoic, Late Palaeozoic and late Tertiary glaciations, lead one to doubt the reality of homeostatic control of surface conditions as proposed in Lovelock's Gaia hypothesis. The Gaian
kuberne0te0s
(steersman) had a weak hand on the helm, frequently unable to prevent vast areas of the globe experiencing rapid fluctuations in environmental conditions and inimical conditions to life for very long periods during Neoproterozoic and Phanerozoic times. At the same time, biogenic and abiogenic processes have proved capable of returning Earth to states of mean stability, although biogeochemical cycling models seem alarmingly
ad hoc
and largely untestable as scientific hypotheses in any true geological sense.
From orogenic hinterlands to Mediterranean-style back-arc basins: a comparative analysis
Authors: PLATT J.P.
Published: February 2007

Hinterland plateaux and Mediterranean-style back-arc basins both form behind active subduction zones or collisional megathrusts, and share many characteristics: (1) early crustal thickening to about twice normal continental thickness; (2) thin lithospheric mantle; (3) mixed magmatism including asthenospheric, lithospheric, and crustal melts; (4) late-stage horizontal extension accompanied by vertical shortening. Horizontal extension and vertical shortening are driven by high gravitational potential energy (GPE) contrasts between the hinterland and surrounding lithosphere, which may reach 7 × 10
12
N m
−1
, equivalent to about 2.5 times the ridge-push force. If extension is rapid relative to the rate of lithospheric cooling, GPE may remain positive even as extension continues, declining to the mid-ocean-ridge value as crustal thickness approaches zero. This suggests that hinterland plateaux could ultimately evolve into oceanic back-arc basins. The rate, direction, and amount of extension, and the rate of vertical shortening, depend on the plate boundary conditions and the GPE of the surrounding lithosphere. Vertical shortening in Tibet is limited by work required to deform the surrounding Asian lithosphere, whereas Mediterranean back-arc basins can extend at the expense of regions of thin continental or oceanic crust.
Sedimentary basin and detrital zircon record along East Laurentia and Baltica during assembly and breakup of Rodinia
Authors: Cawood Peter A. , Nemchin Alexander A. , Strachan Rob , Prave Tony , Krabbendam Maarten
Published: February 2007

Tectonic processes associated with supercontinent cycles result in a variety of basin types, and the isotopic dating of detrital minerals within sedimentary sequences assists palaeogeographical reconstructions. Basins located along the Laurentia–Baltica margin prior to assembly of Rodinia at 1.2–1.0 Ga are dominated by zircon detritus derived from contemporaneous magmatic arcs. Basins formed during assembly are also dominated by zircon detritus with ages similar to that of sediment accumulation, reflecting syn-collisional magmatism and rapid exhumation of the developing Grenville–Sveconorwegian orogen. Post-collision intracratonic basins lack input from syn-depositional magmatism, and are dominated by significantly older detritus derived from the mountain range as well as its foreland. Basins formed during late Neoproterozoic to Cambrian breakup of Rodinia are divisible into two types. Those within the Caledonides lie on the Grenville–Sveconorwegian foreland and incorporate Archaean and Palaeoproterozoic detritus derived from the cratonic interior and Mesoproterozoic detritus derived from the eroded remnants of the orogen. In the Appalachian orogen, such basins are dominated by Mesoproterozoic detritus with older detritus forming only a minor component, suggesting restricted input from the cratonic interior as a result of either the Grenville orogen still forming a drainage divide or the formation of rift shoulders.
Electromigration of Fe and Cr in Liquid Bi
Authors: Epstein S. G. , Weeks J. R.
Published: February 2007

Abstract not Available.
Hypoxia reduces KCa channel activity by inducing Ca2+ spark uncoupling in cerebral artery smooth muscle cells
Authors: Zhao Guiling , Adebiyi Adebowale , Xi Qi , Jaggar Jonathan H.
Published: February 2007

Arterial smooth muscle cell large-conductance Ca2+-activated potassium (KCa) channels have been implicated in modulating hypoxic dilation of systemic arteries, although this is controversial. KCa channel activity in arterial smooth muscle cells is controlled by localized intracellular Ca2+ transients, termed Ca2+ sparks, but hypoxic regulation of Ca2+ sparks and KCa channel activation by Ca2+ sparks has not been investigated. We report here that in voltage-clamped (−40 mV) cerebral artery smooth muscle cells, a reduction in dissolved O2 partial pressure from 150 to 15 mmHg reversibly decreased Ca2+ spark-induced transient KCa current frequency and amplitude to 61% and 76% of control, respectively. In contrast, hypoxia did not alter Ca2+ spark frequency, amplitude, global intracellular Ca2+ concentration, or sarcoplasmic reticulum Ca2+ load. Hypoxia reduced transient KCa current frequency by decreasing the percentage of Ca2+ sparks that activated a transient KCa current from 89% to 63%. Hypoxia reduced transient KCa current amplitude by attenuating the amplitude relationship between Ca2+ sparks that remained coupled and the evoked transient KCa currents. Consistent with these data, in inside-out patches at −40 mV hypoxia reduced KCa channel apparent Ca2+ sensitivity and increased the Kd for Ca2+ from ∼17 to 32 μM, but did not alter single-channel amplitude. In summary, data indicate that hypoxia reduces KCa channel apparent Ca2+ sensitivity via a mechanism that is independent of cytosolic signaling messengers, and this leads to uncoupling of KCa channels from Ca2+ sparks. Transient KCa current inhibition due to uncoupling would oppose hypoxic cerebrovascular dilation.
Gonadal steroid receptors colocalize with central nervous system neurons projecting to the rat prostate gland
Authors: Huddleston Gloria G. , Song C. Kay , Paisley Jacquelyn C. , Bartness Timothy J. , Clancy Andrew N.
Published: February 2007

Mating-induced Fos-immunoreactive (-ir) cells are colocalized with androgen receptors (AR), estrogen receptors (ER), or both in limbic and hypothalamic areas known to mediate male rat mating behavior. A steroid-responsive neural network might govern copulatory behavior in male laboratory rats that is analogous to the network described in female rats that governs the lordosis response. This hypothesized network in males may synchronize and coordinate sexual behavioral responses with physiological responses of the genitals and the internal organs of reproduction. Therefore, the pseudorabies virus (PRV; Bartha strain), a transneuronal, viral retrograde tract tracer, was microinjected into the prostate gland to label this network. After 7 days, brains from infected animals were processed for immunohistochemical labeling of AR, ER, and PRV. The majority of PRV-ir cells exhibited either AR or ER immunoreactivity in the medial preoptic area, median preoptic nucleus, bed nucleus of stria terminalis, hypothalamic paraventricular nucleus, and zona incerta, areas known to play roles in male rat mating behavior. Other structures such as the central tegmental field/subparafascicular nucleus of the thalamus, central nucleus of the amygdala, and medial amygdala, also important in the display of male copulatory behavior, were less reliably labeled. Collectively, a steroid receptor-containing neuronal circuit, largely contained in the diencephalon, was revealed that likely is involved in the autonomic control of the prostate gland and the consummatory aspects of male rat mating behavior.
Gating Information by Two-State Membrane Potential Fluctuations
Authors: Kepecs A. , Raghavachari S.
Published: February 2007

Two-state voltage fluctuations between a hyperpolarized down-state and a depolarized up-state have been observed experimentally in a wide variety of neurons across brain regions. Using a biophysical model, we show that synaptic input by NMDA receptors can cause such membrane potential fluctuations. In this model, when a neuron is driven by two input pathways with different AMPA/NMDA receptor content, the NMDA-rich input causes up-state transitions, whereas the AMPA-rich input generates spikes only in the up-state. Therefore the NMDA-rich pathway can gate input from an AMPA pathway in an all-or-none fashion by switching between different membrane potential states. Furthermore, once in the up-state, the NMDA-rich pathway multiplicatively increases the gain of a neuron responding to AMPA-rich input. This proposed mechanism for two-state fluctuations directly suggests specific computations, such as gating and gain modulation based on the distinct receptor composition of different neuronal pathways. The dynamic gating of input by up- and down-states may be an elementary operation for the selective routing of signals in neural circuits, which may explain the ubiquity of two-state fluctuations across brain regions.
Action Potential Initiation and Propagation in CA3 Pyramidal Axons
Authors: Meeks Julian P. , Mennerick Steven
Published: February 2007

Thin, unmyelinated axons densely populate the mammalian hippocampus and cortex. However, the location and dynamics of spike initiation in thin axons remain unclear. We investigated basic properties of spike initiation and propagation in CA3 neurons of juvenile rat hippocampus. Sodium channel alpha subunit distribution and local applications of tetrodotoxin demonstrate that the site of first threshold crossing in CA3 neurons is ∼35 μm distal to the soma, somewhat more proximal than our previous estimates. This discrepancy can be explained by the finding, obtained with simultaneous whole cell somatic and extracellular axonal recordings, that a zone of axon stretching to ∼100 μm distal to the soma reaches a maximum rate of depolarization nearly synchronously by the influx of sodium from the high-density channels. Models of the proximal axon incorporating observed distributions of sodium channel staining recapitulated salient features of somatic and axonal spike waveforms, including the predicted initiation zone, characteristic spike latencies, and conduction velocity. The preferred initiation zone was unaltered by stimulus strength or repetitive spiking, but repetitive spiking increased threshold and significantly slowed initial segment recruitment time and conduction velocity. Our work defines the dynamics of initiation and propagation in hippocampal principal cell axons and may help reconcile recent controversies over initiation site in other axons.
Multiple Contributions of an Input-Representing Neuron to the Dynamics of the Aplysia Feeding Network
Authors: Proekt Alex , Jing Jian , Weiss Klaudiusz R.
Published: February 2007

In Aplysia, mutually antagonistic ingestive and egestive behaviors are produced by the same multifunctional central pattern generator (CPG) circuit. Interestingly, higher-order inputs that activate the CPG do not directly specify whether the resulting motor program is ingestive or egestive because the slow dynamics of the network intervene. One input, the commandlike cerebral–buccal interneuron 2 (CBI-2), slowly drives the motor output toward ingestion, whereas another input, the esophageal nerve (EN), drives the motor output toward egestion. When the input is switched from EN to CBI-2, the motor output does not switch immediately and remains egestive. Here, we investigated how these slow dynamics are implemented on the interneuronal level. We found that activity of two CPG interneurons, B20 and B40, tracked the motor output regardless of the input, whereas activity of another CPG interneuron, B65, tracked the input regardless of the motor output. Furthermore, we show that the slow dynamics of the network are implemented, at least in part, in the slow dynamics of the interaction between the input-representing and the output-representing neurons. We conclude that 1) a population of CPG interneurons, recruited during a particular motor program, simultaneously encodes both the input that is used to elicit the motor program and the output elicited by this input; and 2) activity of the input-representing neurons may serve to bias the future motor programs.
Quantitative Detection of Micrometastases in Pelvic Lymph Nodes in Patients with Clinically Localized Prostate Cancer by Real-time Reverse Transcriptase-PCR
Authors: Miyake Hideaki , Hara Isao , Kurahashi Toshifumi , Inoue Taka-aki , Eto Hiroshi , Fujisawa Masato
Published: February 2007

Purpose: Routine pathologic examination can miss micrometastatic tumor foci in the lymph nodes of patients with prostate cancer, resulting in confusion during tumor staging and clinical decision-making. The objective of this study was to clarify the significance of micrometastases in pelvic lymph nodes in patients who underwent radical prostatectomy for prostate cancer.

Experimental Design: The expression of prostate-specific antigen (PSA) and prostate-specific membrane antigen (PSMA) in 2,215 lymph nodes isolated from 120 patients with clinically localized prostate cancer was assessed by a fully quantitative real-time reverse transcriptase-PCR. We regarded specimens in which either PSA or PSMA mRNAs were positive as proof of the “presence of micrometastasis.” Immunohistochemical staining of lymph node specimens with an antibody against PSA was also done.

Results: Pathologic examinations detected tumor cells in 29 lymph nodes from 11 patients, and real-time reverse transcriptase-PCR further identified micrometastasis in 143 lymph nodes from 32 patients with no pathologic evidence of lymph node involvement. The presence of micrometastatic cancer cells was confirmed by immunohistochemical staining in 61 lymph nodes from 17 patients with pathologically negative lymph nodes. The presence of micrometastases was significantly associated with other conventional prognostic variables, including serum PSA value, pathologic stage, Gleason score, and tumor volume. Biochemical recurrence was detected in 32 patients, 17 of whom were negative for lymph node metastasis by pathologic examination (including 4 patients with pathologically organ-confined disease), but were diagnosed as having micrometastasis. Biochemical recurrence–free survival rate in patients without micrometastasis was significantly higher than in those with micrometastasis irrespective of the presence of pathologically positive nodes. Furthermore, only the presence of micrometastasis was independently associated with biochemical recurrence regardless of other factors examined.

Conclusions: These findings suggest that ∼30% of clinically localized prostate cancers shed cancer cells to the pelvic lymph nodes, and that biochemical recurrence after radical prostatectomy could be explained, at least in part, by micrometastases in pelvic lymph nodes.
Gene Expression Profiling Reveals Potential Biomarkers of Human Hepatocellular Carcinoma
Authors: Jia Hu-Liang , Ye Qing-Hai , Qin Lun-Xiu , Budhu Anuradha , Forgues Marshonna , Chen Yidong , Liu Yin-Kun , Sun Hui-Chuan , Wang Lu , Lu Hong-Zhou , Shen Fang , Tang Zhao-You , Wang Xin Wei
Published: February 2007

Purpose: Hepatocellular carcinoma (HCC), a common cancer worldwide, has a dismal outcome partly due to the poor identification of early-stage HCC. Currently, one third of HCC patients present with low serum α-fetoprotein (AFP) levels, the only clinically available diagnostic marker for HCC. The aim of this study was to identify new diagnostic molecular markers for HCC, especially for individuals with low serum AFP.

Experimental Design: We used the microarray technique to determine the expression profiles of 218 HCC specimens from patients with either high or low serum AFP. From the microarray study, we selected five candidate genes (i.e., GPC3, PEG10, MDK, SERPINI1, and QP-C), which were overexpressed in HCCs. Using quantitative real-time PCR analyses, we validated the expression of these five genes in 50 AFP-normal and 8 AFP-positive HCC specimens and 36 cirrhotic noncancerous hepatic specimens, which include 52 independent specimens not used in microarray analysis.

Results: A significant increase in the expression of the five candidate genes could be detected in most of the HCC samples, including those with normal serum AFP and small tumors. GPC3, MDK, and SERPINI1 encode known serum proteins. Consistently, a significant increase in serum midkine, encoded by MDK, was associated with HCC patients, including those with normal serum AFP. Using prediction analysis of microarray, we showed that a combined score of these five genes can accurately classify noncancerous hepatic tissues (100%) and HCC (71%).

Conclusions: We suggest that a diagnostic signature approach using a combined score of these five biomarkers rather than a single marker may improve the prediction accuracy of HCC patients, including those with normal serum AFP and smaller-sized tumors.
A Phase I Pharmacokinetic and Pharmacodynamic Study of Intravenous Calcitriol in Combination with Oral Gefitinib in Patients with Advanced Solid Tumors
Authors: Fakih Marwan G. , Trump Donald L. , Muindi Josephia R. , Black Jennifer D. , Bernardi Ronald J. , Creaven Patrick J. , Schwartz James , Brattain Michael G. , Hutson Alan , French Renee , Johnson Candace S.
Published: February 2007

Purpose: In preclinical models, calcitriol and the tyrosine kinase inhibitor gefitinib are synergistic and modulate extracellular signal-regulated kinase (Erk) and Akt pathways. Therefore, we conducted a phase I study of calcitriol and gefitinib to determine the maximum tolerated dose (MTD) of this combination.

Experimental Design: Calcitriol was given i.v. over 1 h on weeks 1, 3, and weekly thereafter. Gefitinib was given at a fixed oral daily dose of 250 mg starting at week 2 (day 8). Escalation occurred in cohorts of three patients until the MTD was defined. Pharmacokinetic studies were done for calcitriol and gefitinib. Serial skin biopsies were done to investigate epidermal growth factor receptor (EGFR) pathway pharmacodynamic interactions.

Results: Thirty-two patients were treated. Dose-limiting hypercalcemia was noted in two of four patients receiving 96 μg/wk of calcitriol. One of seven patients developed dose-limiting hypercalcemia at the MTD 74 μg/wk calcitriol dose level. The relationship between calcitriol dose and peak serum calcitriol (Cmax) and systemic exposure (AUC) was linear. Mean (±SD) serum calcitriol Cmax at the MTD was 6.68 ± 1.42 ng/mL. Gefitinib treatment inhibited EGFR, Akt, and Erk phosphorylation in the skin. Calcitriol did not have consistent effects on skin EGFR or its downstream elements. The combination of gefitinib and calcitriol did not modulate tumor EGFR pathway in patients with serial tumor biopsies.

Conclusions: High doses of weekly i.v. calcitriol can be administered safely in combination with gefitinib. Calcitriol concentrations achieved at the MTD 74 μg calcitriol exceed in vivo concentrations associated with antitumor activity in preclinical models.
DNA Mismatch Repair Initiates 6-Thioguanine–Induced Autophagy through p53 Activation in Human Tumor Cells
Authors: Zeng Xuehuo , Yan Tao , Schupp Jane E. , Seo Yuji , Kinsella Timothy J.
Published: February 2007

Purpose: We investigate the roles of DNA mismatch repair (MMR) and p53 in mediating the induction of autophagy in human tumor cells after exposure to 6-thioguanine (6-TG), a chemotherapy drug recognized by MMR. We also examine how activation of autophagy affects apoptosis (type I cell death) after MMR processing of 6-TG.

Experimental Design: Using isogenic pairs of MLH1−/MLH1+ human colorectal cancer cells (HCT116) and MSH2−/MSH2+ human endometrial cancer cells (HEC59), we initially measure activation of autophagy for up to 3 days after 6-TG treatment using LC3, a specific marker of autophagy. We then assess the role of p53 in autophagic signaling of 6-TG MMR processing using both pifithrin-α cotreatment to chemically inhibit p53 transcription and small hairpin RNA inhibition of p53 expression. Finally, we use Atg5 small hairpin RNA inhibition of autophagy to assess the effect on apoptosis after MMR processing of 6-TG.

Results: We find that MMR is required for mediating autophagy in response to 6-TG treatment in these human tumor cells. We also show that p53 plays an essential role in signaling from MMR to the autophagic pathway. Finally, our results indicate that 6-TG–induced autophagy inhibits apoptosis after MMR processing of 6-TG.

Conclusions: These data suggest a novel function of MMR in mediating autophagy after a chemical (6-TG) DNA mismatch damage through p53 activation. The resulting autophagy inhibits apoptosis after MMR processing of 6-TG.
Computational Modeling to Predict Effect of Treatment Schedule on Drug Delivery to Prostate in Humans
Authors: Hu Leijun , Au Jessie L-S. , Wientjes M. Guillaume
Published: February 2007

Purpose: To evaluate a computational approach that incorporates experimental data in preclinical models to depict doxorubicin human tissue pharmacokinetics.

Experimental Design: Beagle dogs were given 2 mg/kg doxorubicin as i.v. bolus, 4-h infusion, or 96-h infusion. Concentrations in plasma, prostate (target tissue), heart (toxicity), and major tissues for disposition were determined and modeled. Model parameters were obtained after the bolus injection with model validation based on the 4-h and 96-h infusion data. Clinical pharmacokinetic data and scale-up gave doxorubicin profiles in human prostate and heart.

Results: In agreement with in vitro results, tissues were best modeled with two compartments, one rapidly and one slowly equilibrating. The developed tissue distribution model predicted concentrations for all three administration regimens well, with an average deviation of 34% (median, 29%). Interspecies scale-up to humans showed that the change from a bolus injection to a slow, 96-h infusion (a) had different effects on the drug partition and accumulation in heart and prostate, and (b) lowered the peak concentration in the plasma by ∼100-fold but had relatively little effect on maximal heart concentration (∼33% lower). The simulated drug exposure in a human prostate was above the exposure required to inhibit tumor proliferation but was 30 to 50 times below that needed for cell death.

Conclusion: The present study shows a computation-based paradigm for translating in vitro and in vivo preclinical data and to estimate and compare the drug delivery and pharmacokinetics in target tissues after different treatment schedules.
A Susceptibility Gene Set for Early Onset Colorectal Cancer That Integrates Diverse Signaling Pathways: Implication for Tumorigenesis
Authors: Hong Yi , Ho Kok Sun , Eu Kong Weng , Cheah Peh Yean
Published: February 2007

Purpose: The causative genes for autosomal dominantly inherited familial adenomatous polyposis (FAP) and hereditary nonpolyposis colorectal cancer have been well characterized. There is, however, another 10% to 15% of early onset colorectal cancers (CRC) in which the genetic components are unclear. In this study, we used microarray technology to systematically search for differentially expressed genes in early onset CRC.

Experimental Design: Young patients with non–FAP or non–hereditary nonpolyposis colorectal cancer, and healthy controls were age- (≤50 years old), ethnicity- (Chinese), and tissue-matched. RNAs extracted from colonic mucosa specimens were analyzed using GeneChip U133-Plus 2.0 Array.

Results: Seven genes, CYR61, UCHL1, FOS, FOS B, EGR1, VIP, and KRT24, were consistently up-regulated in the mucosa of all six patients compared with the mucosa from four healthy controls. The overexpression of these genes was independently validated with a testing set of six patients and six healthy controls. Principal component analysis clustered the healthy control specimens separately from the patient specimens. Real-time PCR quantification with SYBR-Green on nine other patient specimens not previously used in microarray assays confirmed the up-regulation of these seven genes. These genes function in a multitude of biological processes ranging from transcription, angiogenesis, adhesion, and inflammatory regulation to protein catabolism in various cellular compartments, from extracellular to the nucleus. They integrate known tumorigenesis (Wnt, PI3K, MAP kinase, hypoxia, G protein–coupled receptor), neurologic, insulin-signaling, and NFAT-immune pathways into an intricate biological network.

Conclusions: The data suggest that the patient's mucosa is primed for tumorigenesis when cellular homeostasis is disrupted, and that the seven overexpressed genes could potentially predict early onset CRC.
Detection of Human Papillomavirus-16 in Fine-Needle Aspirates to Determine Tumor Origin in Patients with Metastatic Squamous Cell Carcinoma of the Head and Neck
Authors: Begum Shahnaz , Gillison Maura L. , Nicol Theresa L. , Westra William H.
Published: February 2007

Purpose: Patients with head and neck squamous cell carcinoma (HNSCC) often clinically present with metastases to regional lymph nodes. Fine-needle aspiration of neck masses is routinely used to establish the presence of metastatic carcinoma and in turn to initiate a subsequent workup to determine the site of tumor origin. Human papillomavirus (HPV) 16 is an important etiologic agent for HNSCCs that arise from the oropharynx but less so for tumors from non-oropharyngeal sites. HPV16 detection thus provides a strategy for localizing an important subset of HNSCCs, but this approach has not been applied to fine-needle aspiration specimens.

Experimental Design: We did in situ hybridization for HPV16 on 77 consecutive aspirated neck masses diagnosed as metastatic squamous cell carcinoma. P16 immunohistochemistry was also done because p16 overexpression may serve as a surrogate marker of HPV-associated HNSCC.

Results: HPV16 was detected in 13 of the 77 (17%) aspirates. By site of origin, HPV16 was detected in 10 of 19 metastases from the oropharynx but in none of 46 metastases from other sites (53% versus 0%; P < 0.0001). HPV16 was not detected in 2 branchial cleft cysts misdiagnosed as metastatic squamous cell carcinoma, but it was detected in 3 of 10 metastases from occult primary tumors. P16 expression was associated with the presence of HPV16: 12 of 13 HPV16-positive metastases exhibited p16 expression, whereas only 4 of 62 HPV16-negative metastases were p16 positive (92% versus 6%; P < 0.0001). P16 expression also correlated with site of tumor origin: 13 of 19 oropharyngeal metastases were p16 positive, whereas only 1 of 46 non-oropharyngeal metastases was p16 positive (68% versus 2%; P < 0.0001).

Conclusions: HPV16 status can be determined in tumor cells aspirated from the necks of patients with metastatic HNSCC. Its presence is a reliable indicator of origin from the oropharynx.
Abrogation of MAPK and Akt Signaling by AEE788 Synergistically Potentiates Histone Deacetylase Inhibitor-Induced Apoptosis through Reactive Oxygen Species Generation
Authors: Yu Chunrong , Friday Bret B. , Lai Jin-Ping , McCollum Andrea , Atadja Peter , Roberts Lewis R. , Adjei Alex A.
Published: February 2007

Purpose: To evaluate the effects of combining the multiple receptor tyrosine kinase inhibitor AEE788 and histone deacetylase (HDAC) inhibitors on cytotoxicity in a broad spectrum of cancer cell lines, including cisplatin-resistant ovarian adenocarcinoma cells.

Experimental Design: Multiple cancer cell lines were treated in vitro using AEE788 and HDAC inhibitors (LBH589, LAQ824, and trichostatin A), either alone or in combination. Effects on cytotoxicity were determined by growth and morphologic assays. Effects of the combination on cell signaling pathways were determined by Western blotting, and the results were confirmed using pathway-specific inhibitors and transfection of constitutively active proteins.

Results: Cell treatment with AEE788 and HDAC inhibitors (LBH589, LAQ824, and trichostatin A) in combination resulted in synergistic induction of apoptosis in non–small cell lung cancer (MV522, A549), ovarian cancer (SKOV-3), and leukemia (K562, Jurkat, and ML-1) cells and in OV202hp cisplatin-resistant human ovarian cancer cells. AEE788 alone or in combination with LBH589 inactivated mitogen-activated protein kinase (MAPK) and Akt cascades. Inhibition of either MAPK and/or Akt enhanced LBH589-induced apoptosis. In contrast, constitutively active MAPK or Akt attenuated LBH589 or LBH589 + AEE788–induced apoptosis. Increased apoptosis was correlated with enhanced reactive oxygen species (ROS) generation. The free radical scavenger N-acetyl-l-cysteine not only substantially suppressed the ROS accumulation but also blocked the induction of apoptosis mediated by cotreatment with AEE788 and LBH589.

Conclusion: Collectively, these results show that MAPK and Akt inactivation along with ROS generation contribute to the synergistic cytotoxicity of the combination of AEE788 and HDAC inhibitors in a variety of human cancer cell types. This combination regimen warrants further preclinical and possible clinical study for a broad spectrum of cancers.
Initial Modulation of the Tumor Microenvironment Accounts for Thalidomide Activity in Prostate Cancer
Authors: Efstathiou Eleni , Troncoso Patricia , Wen Sijin , Do Kim-Anh , Pettaway Curtis A. , Pisters Louis L. , McDonnell Timothy J. , Logothetis Christopher J.
Published: February 2007

Purpose: Disruption of stromal-epithelial interactions favoring prostate cancer progression may affect the phenotype of the disease. We did a preoperative study to test the hypothesis that thalidomide, an active agent in metastatic disease, is a modulator of the tumor microenvironment.

Experimental Design: Eighteen men with high-risk prostate cancer were given thalidomide at doses escalated to 600 mg for 12 weeks, followed by radical prostatectomy. We constructed tissue microarrays from prostatectomy specimens from 15 treated patients and 15 matched untreated control subjects to assess effects of thalidomide on the tumor microenvironment. We compared the immunohistochemical expression of three groups of markers linked to angiogenesis, stromal-epithelial interactions, or the epithelial compartment. Levels of circulating basic fibroblast growth factor, interleukin-6, tumor necrosis factor-α, and vascular endothelial growth factor were also assessed.

Results: Thalidomide was well tolerated and induced a median reduction in prostate-specific antigen of 41% without affecting testosterone. Tissue microarray analyses indicated modulation of vascular marker expression accompanied by a reduction in microvessel density in the treated group. Comparison of broader stromal-epithelial interaction markers between treated and control groups suggested a transition to a less aggressive phenotype as a result of thalidomide treatment. Hedgehog signaling was attenuated and the ratio of matrix metalloproteinases to E-cadherin shifted to favor E-cadherin. No differences were noted in proliferation or apoptosis in the epithelial compartment.

Conclusions: These findings are the first clinical evidence to support the hypothesis that the reported thalidomide clinical efficacy is attributable to early modulation of the tumor microenvironment and suggest that stromal-targeting therapies will be effective against prostate cancer.
Toll-like Receptor-4 Is Up-Regulated in Hematopoietic Progenitor Cells and Contributes to Increased Apoptosis in Myelodysplastic Syndromes
Authors: Maratheftis Christos I. , Andreakos Evangelos , Moutsopoulos Haralampos M. , Voulgarelis Michael
Published: February 2007

Purpose: To investigate the function and expression of Toll-like receptors (TLR) in bone marrow cells of myelodysplastic syndrome (MDS) patients and to examine their involvement in the apoptotic phenomenon characterizing MDS hematopoiesis.

Experimental Design: TLR mRNA and protein expression was investigated in bone marrow cell populations of MDS patients and controls. TLR-4 ability to recognize lipopolysaccharide and up-regulate self mRNA and protein expression was examined. Tumor necrosis factor involvement in the constitutive and lipopolysaccharide (LPS)-induced TLR expression was also evaluated. Possible correlation between TLR-4 overexpression and apoptosis was investigated by simultaneous staining with Annexin V and TLR-4.

Results: TLR-2 and TLR-4 are expressed in almost all bone marrow cell lineages including megakaryocytes, erythroid cells, myeloid precursors, monocytes, and B lymphocytes and are up-regulated in MDS patients compared with controls. In hematopoietic CD34+ cells, TLR-4 is also expressed and significantly up-regulated at both the mRNA and protein levels. Treatment with an anti–tumor necrosis factor antibody reduces both constitutive and LPS-induced TLR-4 levels. Increased TLR-4 expression correlates with increased apoptosis as TLR-4 is almost exclusively found in apoptotic bone marrow mononuclear and CD34+ cells. The addition of the TLR-4 ligand LPS further enhances the apoptosis of these cells.

Conclusions: TLR-4 and other TLRs are significantly up-regulated in MDS patients whereas TLR-4 is involved in promoting apoptosis, possibly contributing to MDS cytopenia.
Phase II Trial of Bevacizumab and Irinotecan in Recurrent Malignant Glioma
Authors: Vredenburgh James J. , Desjardins Annick , Herndon James E. , Dowell Jeannette M. , Reardon David A. , Quinn Jennifer A. , Rich Jeremy N. , Sathornsumetee Sith , Gururangan Sridharan , Wagner Melissa , Bigner Darell D. , Friedman Allan H. , Friedman Henry S.
Published: February 2007

Purpose: Recurrent grade III-IV gliomas have a dismal prognosis with minimal improvements in survival seen following currently available salvage therapy. This study was conducted to determine if the combination of a novel antiangiogenic therapy, bevacizumab, and a cytotoxic agent, irinotecan, is safe and effective for patients with recurrent grade III-IV glioma.

Experimental Design: We conducted a phase II trial of bevacizumab and irinotecan in adults with recurrent grade III-IV glioma. Patients with evidence of intracranial hemorrhage on initial brain magnetic resonance imaging were excluded. Patients were scheduled to receive bevacizumab and irinotecan i.v. every 2 weeks of a 6-week cycle. Bevacizumab was administered at 10 mg/kg. The dose of irinotecan was determined based on antiepileptic use: patients taking enzyme-inducing antiepileptic drugs received 340 mg/m2, whereas patients not taking enzyme-inducing antiepileptic drugs received 125 mg/m2. Toxicity and response were assessed.

Results: Thirty-two patients were assessed (23 with grade IV glioma and 9 with grade III glioma). Radiographic responses were noted in 63% (20 of 32) of patients (14 of 23 grade IV patients and 6 of 9 grade III patients). The median progression-free survival was 23 weeks for all patients (95% confidence interval, 15-30 weeks; 20 weeks for grade IV patients and 30 weeks for grade III patients). The 6-month progression-free survival probability was 38% and the 6-month overall survival probability was 72%. No central nervous system hemorrhages occurred, but three patients developed deep venous thromboses or pulmonary emboli, and one patient had an arterial ischemic stroke.

Conclusions: The combination of bevacizumab and irinotecan is an active regimen for recurrent grade III-IV glioma with acceptable toxicity.