bluuebunny/crossref_metadata_2025 huggingface dataset:
Selection on Gamete Recognition Proteins Depends on Sex, Density, and Genotype Frequency
Authors: Levitan Don R. , Ferrell David L.
Published: April 2006

Gamete recognition proteins can evolve at astonishing rates and lie at the heart of reproductive isolation and speciation in diverse taxa. However, the source of selection driving this evolution remains unknown. We report on how the sperm bindin genotype influences reproductive success under natural conditions. An interaction between genotype frequency and spawning density determines how sperm bindin genotype influences reproductive success. Common genotypes are selected under sperm-limited conditions, whereas rare genotypes are selected under conditions of intense sperm competition and sexual conflict. Variation in the evolutionary rates of bindin may reflect historic differences in sperm availability.
Conformational Switches Modulate Protein Interactions in Peptide Antibiotic Synthetases
Authors: Koglin Alexander , Mofid Mohammad R. , Löhr Frank , Schäfer Birgit , Rogov Vladimir V. , Blum Marc-Michael , Mittag Tanja , Marahiel Mohamed A. , Bernhard Frank , Dötsch Volker
Published: April 2006

Protein dynamics plays an important role in protein function. Many functionally important motions occur on the microsecond and low millisecond time scale and can be characterized by nuclear magnetic resonance relaxation experiments. We describe the different states of a peptidyl carrier protein (PCP) that play a crucial role in its function as a peptide shuttle in the nonribosomal peptide synthetases of the tyrocidine A system. Both apo-PCP (without the bound 4′-phosphopantetheine cofactor) and holo-PCP exist in two different stable conformations. We show that one of the apo conformations and one of the holo conformations are identical, whereas the two remaining conformations are only detectable by nuclear magnetic resonance spectroscopy in either the apo or holo form. We further demonstrate that this conformational diversity is an essential prerequisite for the directed movement of the 4′-PP cofactor and its interaction with externally acting proteins such as thioesterases and 4′-PP transferase.
High Natural Aerosol Loading over Boreal Forests
Authors: Tunved P. , Hansson H.-C. , Kerminen V.-M. , Ström J. , Maso M. Dal , Lihavainen H. , Viisanen Y. , Aalto P. P. , Komppula M. , Kulmala M.
Published: April 2006

Aerosols play a key role in the radiation balance of the atmosphere. Here, we present evidence that the European boreal region is a substantial source of both aerosol mass and aerosol number. The investigation supplies a straightforward relation between emissions of monoterpenes and gas-to-particle formation over regions substantially lacking in anthropogenic aerosol sources. Our results show that the forest provides an aerosol population of 1000 to 2000 particles of climatically active sizes per cubic centimeter during the late spring to early fall period. This has important implications for radiation budget estimates and relevancy for the evaluation of feedback loops believed to determine our future climate.
Piezoelectric Nanogenerators Based on Zinc Oxide Nanowire Arrays
Authors: Wang Zhong Lin , Song Jinhui
Published: April 2006

We have converted nanoscale mechanical energy into electrical energy by means of piezoelectric zinc oxide nanowire (NW) arrays. The aligned NWs are deflected with a conductive atomic force microscope tip in contact mode. The coupling of piezoelectric and semiconducting properties in zinc oxide creates a strain field and charge separation across the NW as a result of its bending. The rectifying characteristic of the Schottky barrier formed between the metal tip and the NW leads to electrical current generation. The efficiency of the NW-based piezoelectric power generator is estimated to be 17 to 30%. This approach has the potential of converting mechanical, vibrational, and/or hydraulic energy into electricity for powering nanodevices.
Mass Spectrometry and Protein Analysis
Authors: Domon Bruno , Aebersold Ruedi
Published: April 2006

Mass spectrometry is a central analytical technique for protein research and for the study of biomolecules in general. Driven by the need to identify, characterize, and quantify proteins at ever increasing sensitivity and in ever more complex samples, a wide range of new mass spectrometry–based analytical platforms and experimental strategies have emerged. Here we review recent advances in mass spectrometry instrumentation in the context of current and emerging research strategies in protein science.
New Tools Provide New Insights in NMR Studies of Protein Dynamics
Authors: Mittermaier Anthony , Kay Lewis E.
Published: April 2006

There is growing evidence that structural flexibility plays a central role in the function of protein molecules. Many of the experimental data come from nuclear magnetic resonance (NMR) spectroscopy, a technique that allows internal motions to be probed with exquisite time and spatial resolution. Recent methodological advancements in NMR have extended our ability to characterize protein dynamics and promise to shed new light on the mechanisms by which these molecules function. Here, we present a brief overview of some of the new methods, together with applications that illustrate the level of detail at which protein motions can now be observed.
Diels-Alder in Aqueous Molecular Hosts: Unusual Regioselectivity and Efficient Catalysis
Authors: Yoshizawa Michito , Tamura Masazumi , Fujita Makoto
Published: April 2006

Self-assembled, hollow molecular structures are appealing as synthetic hosts for mediating chemical reactions. However, product binding has inhibited catalytic turnover in such systems, and selectivity has rarely approached the levels observed in more structurally elaborate natural enzymes. We found that an aqueous organopalladium cage induces highly unusual regioselectivity in the Diels-Alder coupling of anthracene and phthalimide guests, promoting reaction at a terminal rather than central anthracene ring. Moreover, a similar bowl-shaped host attains efficient catalytic turnover in coupling the same substrates (although with the conventional regiochemistry), most likely because the product geometry inhibits the aromatic stacking interactions that attract the planar reagents to the host.
Thermal Preference and Tolerance of Alvinellids
Authors: Girguis Peter R. , Lee Raymond W.
Published: April 2006

The highest oceanic temperatures are found at hydrothermal vents, where the polychaete
Paralvinella sulfincola
lives on vent sulfides within steep and dynamic thermal gradients. To determine
P. sulfincola
thermotolerance and preference, we developed a high-pressure aquarium that mimics in situ thermal gradients and permits
P. sulfincola
to move within the gradient. These polychaetes were thermotaxic, preferring temperatures of 40° to 50°C. Some individuals remained at 50°C for 7 hours (the duration of the experiment), whereas others endured exposure to 55°C for over 15 minutes, demonstrating that alvinellids prefer high temperatures and are among the most thermotolerant of marine organisms.
Living Cells as Test Tubes
Authors: Xie X. Sunney , Yu Ji , Yang Wei Yuan
Published: April 2006

The combination of specific probes and advanced optical microscopy now allows quantitative probing of biochemical reactions in living cells. On selected systems, one can detect and track a particular protein with single-molecule sensitivity, nanometer spatial precision, and millisecond time resolution. Metabolites, usually difficult to detect, can be imaged and monitored in living cells with coherent anti-Stokes Raman scattering microscopy. Here, we describe the application of these techniques in studying gene expression, active transport, and lipid metabolism.
Clinically Relevant Chromosomally Encoded Multidrug Resistance Efflux Pumps in Bacteria
Authors: Piddock Laura J. V.
Published: April 2006

Efflux pump genes and proteins are present in both antibiotic-susceptible and antibiotic-resistant bacteria. Pumps may be specific for one substrate or may transport a range of structurally dissimilar compounds (including antibiotics of multiple classes); such pumps can be associated with multiple drug (antibiotic) resistance (MDR). However, the clinical relevance of efflux-mediated resistance is species, drug, and infection dependent. This review focuses on chromosomally encoded pumps in bacteria that cause infections in humans. Recent structural data provide valuable insights into the mechanisms of drug transport. MDR efflux pumps contribute to antibiotic resistance in bacteria in several ways: (i) inherent resistance to an entire class of agents, (ii) inherent resistance to specific agents, and (iii) resistance conferred by overexpression of an efflux pump. Enhanced efflux can be mediated by mutations in (i) the local repressor gene, (ii) a global regulatory gene, (iii) the promoter region of the transporter gene, or (iv) insertion elements upstream of the transporter gene. Some data suggest that resistance nodulation division systems are important in pathogenicity and/or survival in a particular ecological niche. Inhibitors of various efflux pump systems have been described; typically these are plant alkaloids, but as yet no product has been marketed.
Raised troponin T and echocardiographic abnormalities after prolonged strenuous exercise—the Australian Ironman Triathlon
Authors: Tulloh L , Robinson D , Patel A , Ware A , Prendergast C , Sullivan D , Pressley L
Published: April 2006

Background:There is concern about whether cardiac damage occurs as a result of prolonged strenuous exercise.

Objective:To investigate whether competing in a triathlon is associated with cardiac damage based on a sustained increase in cardiac troponin T (cTnT), and whether such an increase correlates with echocardiographic changes

Methods:cTnT and echocardiographic measurements were made in 38 participants in the 2001 Australian ironman triathlon. cTnT was measured the day before, immediately after, and the day following the race. Echocardiography was done the day before, immediately after, and two to six weeks later for measurement of ejection fraction, stroke volume, cardiac output, wall motion analysis, and global left ventricular function (LVF).

Results:No subject had detectable cTnT in the pre-race sample. Following the race, 32 subjects (86.5%) had detectable levels of cTnT (>0.01 ng/ml), with six (16.2%) having >0.10 ng/ml. The day after the race, nine subjects (23.7%) still had detectable cTnT, with two recording a level >0.10 ng/ml. Previously described echocardiographic changes of “cardiac fatigue” were observed in the whole cohort. There was a modest but significant correlation between change in ejection fraction and peak cTnT level (p = 0.02,r = 0.39). Athletes with a post-race cTnT >0.10 ng/ml had a greater decrease in global LVF (p = 0.02) and a trend toward a greater fall in ejection fraction and stroke volume than athletes with cTnT levels <0.10 ng/ml. Cardiac output fell in the group with cTnT >0.10 ng/ml (p>0.05).

Conclusions:Participation in ironman triathlon often resulted in persistently raised cTnT levels, and the troponin rise was associated with echocardiographic evidence of abnormal left ventricular function. The clinical significance and long term sequelae of such damage remains to be determined.
AN ALGORITHM TO COMPUTE THE UPPER ENTROPY FOR ORDER-2 CAPACITIES
Authors: ABELLÁN JOAQUIN , MORAL SERAFIN
Published: April 2006

The upper entropy of a credal set is the maximum of the entropies of the probabilities belonging to it. Although there are algorithms for computing the upper entropy for the particular cases of credal sets associated to belief functions and probability intervals, there is none for a more general model. In this paper, we shall present an algorithm to obtain the upper entropy for order-2 capacities. Our algorithm is an extension of the one presented for belief functions, and proofs of correctness are provided. By using a counterexample, we shall also prove that this algorithm is not valid for general lower probabilities as it computes a value which is strictly greater than the maximum of entropy.
INTERVAL METHODS IN KNOWLEDGE REPRESENTATION
Authors: Kreinovich Vladik
Published: April 2006

This section is maintained by Vladik Kreinovich. Please send your abstracts (or copies of papers that you want to see reviewed here) to vladik@utep.edu, or by regular mail to: V. Kreinovich, Department of Computer Science, University of Texas, El Paso, TX 79968, USA.
Denervation produces different single fiber phenotypes in fast- and slow-twitch hindlimb muscles of the rat
Authors: Patterson M. F. , Stephenson G. M. M. , Stephenson D. G.
Published: April 2006

Using a single, mechanically skinned fiber approach, we tested the hypothesis that denervation (0 to 50 days) of skeletal muscles that do not overlap in fiber type composition [extensor digitorum longus (EDL) and soleus (SOL) muscles of Long-Evans hooded rats] leads to development of different fiber phenotypes. Denervation (50 day) was accompanied by 1) a marked increase in the proportion of hybrid IIB/D fibers (EDL) and I/IIA fibers (SOL) from 30% to >75% in both muscles, and a corresponding decrease in the proportion of pure fibers expressing only one myosin heavy chain (MHC) isoform; 2) complex muscle- and fiber-type specific changes in sarcoplasmic reticulum Ca2+-loading level at physiological pCa ∼7.1, with EDL fibers displaying more consistent changes than SOL fibers; 3) decrease by ∼50% in specific force of all fiber types; 4) decrease in sensitivity to Ca2+, particularly for SOL fibers (by ∼40%); 5) decrease in the maximum steepness of the force-pCa curves, particularly for the hybrid I/IIA SOL fibers (by ∼35%); and 6) increased occurrence of biphasic behavior with respect to Sr2+ activation in SOL fibers, indicating the presence of both slow and fast troponin C isoforms. No fiber types common to the two muscles were detected at any time points ( day 7, 21, and 50) after denervation. The results provide strong evidence that not only neural factors, but also the intrinsic properties of a muscle fiber, influence the structural and functional properties of a particular muscle cell and explain important functional changes induced by denervation at both whole muscle and single cell levels.
Release of iron from ferritin requires lysosomal activity
Authors: Kidane Theodros Z. , Sauble Eric , Linder Maria C.
Published: April 2006

How ferritin-Fe becomes available for cell functions is unknown. Our previous studies with rat hepatoma cells indicated ferritin had to be degraded to release its Fe. In these studies, we investigated whether this occurs in other cell types and whether lysosomes are required. Release of ferritin-Fe was induced with desferoxamine (DFO) in 59Fe-preloaded hepatoma, Caco2, and erythroid K562 cells and measured by rocket immunoelectrophoresis and autoradiography. The half-lives for ferritin-59Fe and protein were parallel (23, 16, and 11 h for the hepatic, Caco2, and K562 cells, respectively). Co-treatment with 180 μM Fe, leupeptin, chymostatin, or chloroquine markedly decreased rates of ferritin-Fe release and ferritin degradation. Lactacystin had no effect except for a small one in erythroid cells. Fractionation of hepatoma cell lysates on iodixanol gradients showed rapid depletion of cytosolic ferritin by DFO treatment but no accumulation in lysosomes. We conclude that regardless of cell type, release of Fe from ferritin occurs mainly through lysosomal proteolysis.
A simplified noninvasive method to measure airway blood flow in humans
Authors: Wanner Adam , Mendes Eliana S. , Atkins Neal D.
Published: April 2006

Our laboratory has previously developed and validated a noninvasive soluble gas uptake method to measure airway blood flow (Q̇aw) in humans (Onorato DJ, Demirozu MC, Breitenbücher A, Atkins ND, Chediak AD, and Wanner A. Am J Respir Crit Care Med 149: 1132–1137, 1994; Scuri M, McCaskill V, Chediak AD, Abraham WM, and Wanner A. J Appl Physiol 79: 1386–1390, 1995). The method has the disadvantage of requiring eight breath-hold maneuvers for a single Qaw measurement, a complicated data analysis, and the inhalation of a potentially explosive gas mixture containing dimethylether (DME) and O2. Because of these shortcomings, the method thus far has not been used in other laboratories. We now simplified the method by having the subjects inhale 500 ml of a 10% DME-90% N2 gas mixture to fill the anatomical dead space, followed by a 5- or 15-s breath hold, and measuring the instantaneous DME and N2 concentrations and volume at the airway opening during the subsequent exhalation. From the difference in DME concentration in phase 1 of the expired N2 wash-in curve multiplied by the phase 1 dead space volume and divided by the mean DME concentration and the solubility coefficient for DME in tissue, Qaw can be calculated by using Fick's equation. We compared the new method to the validated old method in 10 healthy subjects and found mean ± SE Q̇aw values of 34.6 ± 2.3 and 34.6 ± 2.8 μl·min−1·ml−1, respectively ( r = 0.93; upper and lower 95% confidence limit +2.48 and −2.47). Using the new method, the mean coefficient of variation for two consecutive measurements was 4.4% (range 0–10.4%); inhalation of 1.2 mg albuterol caused a 53 ± 14% increase in Q̇aw ( P = 0.02) and inhalation of 2.4 mg methoxamine caused a 32 ± 7% decrease in Q̇aw ( P = 0.07). We conclude that the new method provides reliable values of and detects the expected changes in Q̇aw with vasoactive drugs. The simplicity and improved safety of the method should improve its acceptability for the noninvasive assessment of Q̇aw in clinical research.
Respiratory and circulatory effects of parietal pleural afferent stimulation in rabbits
Authors: Jammes Yves , Delpierre Stéphane
Published: April 2006

Respiratory symptoms accompanying pleural diseases combine dyspnea, tachypnea, rapid shallow breathing, and sometimes hypotension. There are no experimental data on the changes in respiratory and circulatory functions elicited by the activation of pleural afferents. After removal of all muscles covering the 5th to 10th intercostal spaces, we investigated in paralyzed, vagotomized rabbits the changes in phrenic discharge, transpulmonary pressure, and systemic arterial pressure in response to an outwardly directed force exerted on the parietal pleura or the local application of solutions containing lactic acid or inflammatory mediators. Mechanical stimulation of the pleura induced an immediate decrease in both integrated phrenic discharge and arterial blood pressure, the responses being positively correlated with the magnitude of force applied on the pleura. No accompanying changes in ventilatory timing, transpulmonary pressure, or heart rate were measured. Lactic acid solution also elicited an inhibition of phrenic activity and a fall in blood pressure. Section of the internal intercostal nerves supplying the stimulated intercostal spaces totally abolished the responses to mechanical stimulation or lactic acid. An inflammatory mixture elicited only modest respiratory and circulatory effects. We concluded that an acute mechanical distension of the parietal pleura as well as its chemical stimulation by lactic acid elicit a marked inhibition of phrenic motoneurons combined to a reduction of the sympathetic outflow to the circulatory system.
Position Information But Not Force Information Is Used in Adapting to Changes in Environmental Dynamics
Authors: Milner Theodore E. , Hinder Mark R.
Published: April 2006

This study investigated how movement error is evaluated and used to change feedforward commands following a change in the environmental dynamics. In particular, we addressed the question of whether only position-error information is used or whether information about the force-field direction can also be used for rapid adaptation to changes in the environmental dynamics. Subjects learned to move in a position-dependent force field (PF) with a parabolic profile and the dynamics of a negative spring, which produced lateral force to the left of the target hand path. They adapted very rapidly, dramatically reducing lateral error after a single trial. Several times during training, the strength of the PF was unexpectedly doubled (PF2) for two trials. This again created a large leftward deviation, which was greatly reduced on the second PF2 trial, and an aftereffect when the force field subsequently returned to its original strength. The aftereffect was abolished if the second PF2 trial was replaced by an oppositely directed velocity-dependent force field (VF). During subsequent training in the VF, immediately after having adapted to the PF, subjects applied a force that assisted the force field for ∼15 trials, indicating that they did not use information about the force-field direction. We concluded that the CNS uses only the position error for updating the internal model of the environmental dynamics and modifying feedforward commands. Although this strategy is not necessarily optimal, it may be the most reliable strategy for iterative improvement in performance.
Circuits and Properties of Signal Transmission in the Retina
Authors: Witkovsky Paul , Stell William K. , Ishida Andrew T.
Published: April 2006

This essay looks at the historical significance of three APS classic papers that are freely available online:

Naka K-I and Nye PW.

Role of horizontal cells in organization of the catfish retinal receptive field. J. Neurophysiol 34:785–801, 1971.

Marmarelis PZ and Naka K-I.

Nonlinear analysis and synthesis of receptive-field responses in the catfish retina. II. One-input white-noise analysis. J. Neurophysiol 36: 619–633, 1973.

Naka K-I, Marmarelis PZ, and Chan RY.

Morphological and functional identifications of catfish retinal neurons. III. Functional identification. J. Neurophysiol 38: 92–131, 1975.
Mitochondrial Inhibition Prior to Oxygen-Withdrawal Facilitates the Occurrence of Hypoxia-Induced Spreading Depression in Rat Hippocampal Slices
Authors: Gerich Florian J. , Hepp Sebastian , Probst Irmelin , Müller Michael
Published: April 2006

Oxygen withdrawal blocks mitochondrial respiration. In rat hippocampal slices, this triggers a massive depolarization of CA1 neurons and a negative shift of the extracellular DC potential, the characteristic sign of hypoxia-induced spreading depression (HSD). To unveil the contribution of mitochondria to the sensing of hypoxia and the ignition of HSD, we modified mitochondrial function. Mitochondrial uncoupling by carbonyl cyanide 4-(trifluoromethoxy) phenylhydrazone (FCCP, 1 μM) prior to hypoxia hastened the onset and shortened the duration of HSD. Blocking mitochondrial ATP synthesis by oligomycin (10 μg/ml) was without effect. Inhibition of mitochondrial respiration by rotenone (20 μM), diphenyleneiodonium (25 μM), or antimycin A (20 μM) also hastened HSD onset and shortened HSD duration. 3-nitropropionic acid (1 mM) increased HSD duration. Cyanide (100 μM) hastened HSD onset and increased HSD duration. At higher concentrations, cyanide (1 mM), azide (2 mM), and FCCP (10 μM) triggered SD episodes on their own. Compared with control HSD, the spatial extent of the intrinsic optical signals of cyanide- and azide-induced SDs was more pronounced. Monitoring NADH (nicotinamide adenine dinucleotide) and FAD (flavin adenine dinucleotide) autofluorescence and mitochondrial membrane potential verified the mitochondrial targeting by the drugs used. Except 1 mM cyanide, no treatment reduced cellular ATP levels severely and no correlation was found between ATP, NADH, or FAD levels and the time to HSD onset. Therefore ATP depletion or a cytosolic reducing shift due to NADH/FADH2accumulation cannot serve as a general explanation for the hastening of HSD onset on mitochondrial inhibition. Additional redox couples (glutathione) or events downstream of the mitochondrial depolarization need to be considered.
Developmental Changes in Electrophysiological Properties and Synaptic Transmission in Rat Intracardiac Ganglion Neurons
Authors: Rimmer Katrina , Harper Alexander A.
Published: April 2006

We charted postnatal changes in the intrinsic electrophysiological properties and synaptic responses of rat intrinsic cardiac ganglion (ICG) neurons. We developed a whole-mount ganglion preparation of the excised right atrial ganglion plexus. Using intracellular recordings and nerve stimulation we tested the hypothesis that substantial transformations in the intrinsic electrical characteristics and synaptic transmission accompany postnatal development. Membrane potential ( Em) did not change but time constant (τ) and cell capacitance increased with postnatal development. Accordingly, input resistance ( Rin) decreased but specific membrane resistance ( Rm) increased postnatally. Comparison of the somatic active membrane properties revealed significant changes in electrical phenotype. All neonatal neurons had somatic action potentials (APs) with small overshoots and small afterhyperpolarizations (AHPs). Adult neurons had somatic APs with large overshoots and large AHP amplitudes. The range of AHP duration was larger in adults than in neonates. The AP characteristics of juvenile neurons resembled those of adults, with the exception of AHP duration, which fell midway between neonate and adult values. Phasic, multiply adapting, and tonic evoked discharge activities were recorded from ICG neurons. Most neurons displayed phasic discharge at each developmental stage. All neurons received excitatory synaptic inputs from the vagus or interganglionic nerve trunk(s), the strength of which did not change significantly with postnatal age. The changes in the electrophysiological properties of the postganglionic neuron suggest that increased complexity of parasympathetic regulation of cardiac function accompanies postnatal development.
Selective Inhibition of Spontaneous But Not Ca2+-Dependent Release Machinery by Presynaptic Group II mGluRs in Rat Cerebellar Slices
Authors: Glitsch Maike
Published: April 2006

Two main forms of neurotransmitter release are known: action potential-evoked and spontaneous release. Action potential-evoked release depends on Ca2+entry through voltage-gated Ca2+channels, whereas spontaneous release is thought to be Ca2+-independent. Generally, spontaneous and action potential-evoked release are believed to use the same release machinery to release neurotransmitter. This study shows, using the whole cell patch-clamp technique in rat cerebellar slices, that at the interneuron- Purkinje cell synapse activation of presynaptic group II metabotropic glutamate receptors suppresses spontaneous GABA release through a mechanism independent of voltage-gated Ca2+channels, store-operated Ca2+channels, and Ca2+release from intracellular Ca2+stores, suggesting that the metabotropic receptors target the release machinery directly. Voltage gated Ca2+channel-independent release following increased presynaptic cAMP production is similarly inhibited by these metabotropic receptors. In contrast, both voltage-gated Ca2+channel-dependent and presynaptic N-methyl-d-aspartate receptor-dependent GABA release were unaffected by activation of group II metabotropic glutamate receptors. Hence, the mechanisms underlying spontaneous and Ca2+-dependent GABA release are distinct in that only the former is blocked by group II metabotropic glutamate receptors. Thus the same neurotransmitter, glutamate, can activate or inhibit neurotransmitter release by selecting different receptors that target different release machineries.
Kinetics of Activity-Evoked pH Transients and Extracellular pH Buffering in Rat Hippocampal Slices
Authors: Tong Chi-Kun , Chen Kevin , Chesler Mitchell
Published: April 2006

The kinetics of activity-dependent, extracellular alkaline transients, and the buffering of extracellular pH (pHe), were studied in rat hippocampal slices using a fluorescein-dextran probe. Orthodromic stimuli generated alkaline transients ≤0.05 pH units that peaked in 273 ± 26 ms and decayed with a half-time of 508 ± 43 ms. Inhibition of extracellular carbonic anhydrase (ECA) with benzolamide increased the rate of rise by 25%, doubled peak amplitude, and prolonged the decay three- to fourfold. The slow decay in benzolamide allowed marked temporal summation, resulting in a severalfold increase in amplitude during long stimulus trains. Addition of exogenous carbonic anhydrase reduced the rate of rise, halved the peak amplitude, but had no effect on the normalized decay. A simulation of extracellular buffering kinetics generated recoveries from a base load consistent with the observed decay of the alkaline transient in the presence of benzolamide. Under control conditions, the model approximated the observed decays with an acceleration of the CO2hydration–dehydration reactions by a factor of 2.5. These data suggest low endogenous ECA activity, insufficient to maintain equilibrium during the alkaline transients. Disequilibrium implies a time-dependent buffering capacity, with a CO2/HCO3−contribution that is small shortly after a base load. It is suggested that within 100 ms, extracellular buffering capacity is about 1% of the value at equilibrium and is provided mainly by phosphate. Accordingly, in the time frame of synaptic transmission, small base loads would generate relatively large changes in interstitial pH.
Orexin Neurons Are Directly and Indirectly Regulated by Catecholamines in a Complex Manner
Authors: Yamanaka Akihiro , Muraki Yo , Ichiki Kanako , Tsujino Natsuko , Kilduff Thomas S. , Goto Katsutoshi , Sakurai Takeshi
Published: April 2006

We reported elsewhere that orexin neurons are directly hyperpolarized by noradrenaline (NA) and dopamine. In the present study, we show that NA, dopamine, and adrenaline all directly hyperpolarized orexin neurons. This response was inhibited by the α2 adrenergic receptor (α2-AR) antagonist, idazoxan or BRL44408 , and was mimicked by the α2-AR-selective agonist, UK14304. A low concentration of Ba2+ inhibited NA-induced hyperpolarization, which suggests that activation of G protein coupled inward rectifier potassium channels is involved in the response. In the presence of a high concentration of idazoxan, NA induced depolarization or inward current. This response was inhibited by α1-AR antagonist, prazosin, which suggests the existence of α1-ARs on the orexin neurons along with α2-AR. We also examined the effects of NA on glutamatergic and GABAergic synaptic transmission. NA application dramatically increased the frequency and amplitude of spontaneous inhibitory synaptic currents (sIPSCs) and inhibited excitatory synaptic currents (sEPSCs) in orexin neurons; however, NA decreased the frequency of miniature EPSCs (mEPSCs) and IPSCs and the amplitude of evoked EPSCs and IPSCs through the α2-AR, because the NA response on mPSCs was inhibited by idazoxan. These results suggest that the NA-induced increase in sIPSC frequency and amplitude is mediated via α1-ARs on the somata of GABAergic neurons that innervate the orexin neurons. Calcium imaging using orexin/YC2.1 transgenic mouse brain revealed that NA-induced inhibition of orexin neurons is not altered by sleep deprivation or circadian time in mice. The evidence presented here revealed that orexin neurons are regulated by catecholamines in a complex manner.
Changes in Cancer Registry Coding for Lymphoma Subtypes: Reliability Over Time and Relevance for Surveillance and Study
Authors: Clarke Christina A. , Undurraga Dawn M. , Harasty Patricia J. , Glaser Sally L. , Morton Lindsay M. , Holly Elizabeth A.
Published: April 2006

Because lymphoma comprises numerous histologic subtypes, understanding the reasons for ongoing increases in its incidence requires surveillance and etiologic study of these subtypes. However, this research has been hindered by many coexisting classification schemes. The Revised European American classification of Lymphoid Neoplasms (REAL)/WHO system developed in 1994 and now used in clinical settings was not incorporated into the International Classification of Diseases-Oncology (ICD-O), used by cancer registries, until the release of the third edition (ICD-O-3) in 2001. Studies including patients diagnosed before 2001 may have codes from earlier ICD-O versions that must be converted to ICD-O-3 and have higher proportions of unclassified (e.g., lymphoma and not otherwise specified) cases. To better understand (a) the agreement of computer-converted ICD-O-3 codes to ICD-O-3 codes generated directly from diagnostic pathology reports and (b) the reproducibility of unclassified status, we reviewed a population-based series of diagnostic pathology reports for lymphoma patients diagnosed before (1988-1994; n = 1,493) and after (1998-2000; n = 1,527) the REAL/WHO scheme was introduced. Overall, computer- and coder-assigned ICD-O-3 codes agreed for 77% of patients in both groups and improved slightly (82%) when codes were grouped. The most common lymphoma subtypes, diffuse large B cell and follicular, had relatively good reliability (84-89%) throughout the study period. T-cell and natural killer cell lymphomas had worse agreement than B-cell lymphomas, even when grouped. Many (42-43%) lymphomas reported as unclassifiable could be assigned a subtype upon pathology report review. These findings suggest that the study of lymphoma subtypes could be improved by (a) use of more standardized terminology in pathology reports, (b) grouping individual ICD-O-3 codes to reduce misclassification bias, and (c) routine secondary editing of unclassified lymphomas by central cancer registries. (Cancer Epidemiol Biomarkers Prev 2006;15(4):630–8)
Assessment of DNA Damage in WBCs of Workers Occupationally Exposed to Fumes and Aerosols of Bitumen
Authors: Marczynski Boleslaw , Raulf-Heimsoth Monika , Preuss Ralf , Kappler Martin , Schott Klaus , Pesch Beate , Zoubek Gerd , Hahn Jens-Uwe , Mensing Thomas , Angerer Jürgen , Käfferlein Heiko U. , Brüning Thomas
Published: April 2006

We conducted a cross-shift study with 66 bitumen-exposed mastic asphalt workers and 49 construction workers without exposure to bitumen. Exposure was assessed using personal monitoring of airborne bitumen exposure, urinary 1-hydroxypyrene (1-OHP), and the sum of 1-, 2 + 9–,3-,4-hydroxyphenanthrene (OHPH). Genotoxic effects in WBC were determined with nonspecific DNA adduct levels of 8-oxo-7,8-dihydro-2′-deoxyguanosine (8-oxodGuo) and the formation of DNA strand breaks and alkali-labile sites. Concentration of fumes and aerosols of bitumen correlated significantly with the concentrations of 1-OHP and OHPH after shift (rs = 0.27; P = 0.03 and rs = 0.55; P < 0.0001, respectively). Bitumen-exposed workers had more DNA strand breaks than the reference group (P < 0.0001) at both time points and a significant correlation with 1-OHP and OHPH in the postshift urines (rs = 0.32; P = 0.001 and rs = 0.27; P = 0.004, respectively). Paradoxically, we measured higher levels of DNA strand breaks, although not significant, in both study groups before shift. 8-OxodGuo adduct levels did not correlate with DNA strand breaks. Further, 8-oxodGuo levels were associated neither with personal exposure to bitumen nor with urinary metabolite concentrations. Significantly more DNA adducts were observed after shift not only in bitumen-exposed workers but also in the reference group. Only low-exposed workers had significantly elevated 8-oxodGuo adduct levels before as well as after shift (P = 0.0002 and P = 0.02, respectively). Our results show that exposure to fumes and aerosols of bitumen may contribute to an increased DNA damage assessed with strand breaks. (Cancer Epidemiol Biomarkers Prev 2006;15(4):645–51)
Do Testicular Seminoma and Nonseminoma Share the Same Etiology? Evidence from an Age-Period-Cohort Analysis of Incidence Trends in Eight European Countries
Authors: Bray Freddie , Richiardi Lorenzo , Ekbom Anders , Forman David , Pukkala Eero , Cuninkova Martina , Møller Henrik
Published: April 2006

The incidence of the two main clinical subentities of testicular germ cell cancer (seminoma and nonseminoma) is increasing throughout Europe. Most studies have revealed little variation in risk factors between the two subtypes. This study compared generation-specific trends in eight European countries, hypothesizing that similar temporal pattern by birth cohort implied that seminoma and nonseminoma had a largely comparable etiology. The results are presented using the age-period-cohort model and the nonidentifiability problem highlighted by partitioning the age, period, and cohort effects in terms of their linear and curvature component parts, assuming a priori that cohort effects predominated. Despite uniform overall increases by calendar period, declining rates of nonseminoma but not pure seminoma were observed in the majority of countries during the 1990s. The subtype trends were, however, largely analogous on a birth cohort scale. Notable observations were a decline in rates of both subtypes among recent birth cohorts in Switzerland and a short-term wartime effect in several countries, involving an attenuation of increasing risk of both subtypes in men born in 1940 to 1945. Departures from the steady increases in testicular cancer over time were likely to occur for nonseminomas some years ahead of seminoma on a period scale. The importance of birth cohort coincided with the view that given a short time interval of susceptibility to exposures earlier in life and a biologically constant time to diagnosis, all temporal changes in rate-limiting exposures should appear as generational effects. Trends in seminoma and nonseminoma conform to largely the same temporal patterns on this scale, implying that they share important etiologic factors. (Cancer Epidemiol Biomarkers Prev 2006;15(4):652–8)
GSTP1 Genetic Polymorphism Is Associated with a Higher Risk of DNA Damage in Pesticide-Exposed Fruit Growers
Authors: Liu Yi-Jie , Huang Pei-Lin , Chang Yu-Fen , Chen Yen-Hui , Chiou Yu-Hu , Xu Zong-Lin , Wong Ruey-Hong
Published: April 2006

Pesticide exposure is associated with various neoplastic diseases and congenital malformations. Animal studies also indicated that pesticides may be metabolized by cytochrome P450 3A5 (CYP3A5) enzymes, paraoxonases (PON1 and PON2), or glutathione S-transferases (GSTM1, GSTT1, and GSTP1). However, little is known about the genotoxicity of pesticides in people with various genetic polymorphisms of human CYP3A5, PON1, PON2, GSTM1, GSTT1, and GSTP1. Thus, this study was designed to investigate whether various metabolic genotypes are more susceptible to DNA damage in pesticide-exposed fruit growers. Using the Comet assay, the extent of DNA damage was evaluated in the peripheral blood of 91 fruit growers who experienced pesticide exposure and 106 unexposed controls. Questionnaires were administered to obtain demographic data, cigarette smoking habits, medical, and occupational histories. The genotypes for CYP3A5, PON1, PON2, GSTM1, GSTT1, and GSTP1 genes were identified by PCR. The results showed that subjects experiencing high or low pesticide exposure had a significantly greater DNA tail moment (DAN damage) than did controls. The multiple regression model also revealed that age (P < 0.01), high pesticide exposure (P < 0.01), low pesticide-exposure (P < 0.01), and CYP3A5 (P = 0.04) and GSTP1 (P = 0.02) genotypes were significantly associated with an increased DNA tail moment. Further analysis of environmental and genetic interactions revealed a significant interaction for GSTP1 genotypes to influence DNA tail moment for the high pesticide exposure group. These results suggest that individuals with susceptible metabolic GSTP1 genotypes may experience an increased risk of DNA damage elicited by pesticide exposure. (Cancer Epidemiol Biomarkers Prev 2006;15(4):659–66)
OGG1Polymorphisms and Breast Cancer Risk
Authors: Rossner Pavel , Terry Mary Beth , Gammon Marilie D. , Zhang Fang Fang , Teitelbaum Susan L. , Eng Sybil M. , Sagiv Sharon K. , Gaudet Mia M. , Neugut Alfred I. , Santella Regina M.
Published: April 2006

The role of oxidative stress in breast cancer risk is still unclear. OGG1 encodes an 8-oxoguanine DNA glycosylase/AP lyase that catalyzes the removal of 8-oxodeoxyguanosine from DNA. 8-Oxodeoxyguanosine, the most abundant lesion generated by oxidative stress, is highly mutagenic. Environmental sources of oxidative stress, such as alcohol consumption, cigarette smoking, high body mass index (BMI), and low fruits and vegetables intake, may modify the association of genetic polymorphisms with breast cancer risk. We investigated the association between three genetic polymorphisms in OGG1 (Ser326Cys, 7143A/G, and 11657A/G) and breast cancer risk among 1,058 cases and 1,102 controls participating in the Long Island Breast Cancer Study Project. No associations were observed between individual OGG1 polymorphisms, haplotypes, or diplotypes and breast cancer. The association between having at least one variant allele and breast cancer risk was stronger among moderate alcohol drinkers for Ser326Cys [odds ratio (OR), 1.82; 95% confidence interval (95% CI), 1.06-3.10] relative to nondrinkers with the wild-type genotype and among those with higher BMI for 7143A/G (OR, 1.47; 95% CI, 1.10-1.96) and for 11657A/G (OR, 1.41; 95% CI, 1.05-1.88), relative to women with BMI < 25 kg/m2 and the wild-type genotype. However, the patterns were not seen for all three single nucleotide polymorphisms (SNP) nor were there any clear allele dose associations; only one interaction was statistically significant, assuming a multiplicative model (11657A/G, Pinteraction = 0.04). In summary, although we found some differences between the three OGG1 SNPs and breast cancer risk among moderate alcohol drinkers and women with higher BMI, replication of these results is needed to rule out spurious findings. In addition, data on functionality of these polymorphisms are crucial to understand if these modest differences are important. (Cancer Epidemiol Biomarkers Prev 2006;15(4):811–5)
Pancreatic Cancer Genetic Epidemiology Consortium
Authors: Petersen Gloria M. , de Andrade Mariza , Goggins Michael , Hruban Ralph H. , Bondy Melissa , Korczak Jeannette F. , Gallinger Steven , Lynch Henry T. , Syngal Sapna , Rabe Kari G. , Seminara Daniela , Klein Alison P.
Published: April 2006

We have organized the Pancreatic Cancer Genetic Epidemiology (PACGENE) Consortium to identify susceptibility genes in familial pancreatic cancer (FPC). The Consortium comprises seven data collection centers, a statistical genetics core, and a pathology/archival genotyping core. We recruit kindreds containing two or more affected blood relatives ascertained through incident pancreatic adenocarcinoma cases, physician referrals, and/or through Internet recruitment. Accrual to a database containing core clinical, demographic, lifestyle, and family history information from questionnaires is ongoing, along with biospecimen collection. To date, 13,147 patients have been screened for family history, of whom 476 (50% male) probands and 1,912 of their adult (99% unaffected) relatives have been enrolled. Of these, 379 kindreds meet criteria for FPC, having at least two first-degree relatives with pancreatic cancer. Cumulative incidence curves using available age of diagnosis (onset) among and affected relatives were compared with those for incident pancreatic cancer cases reported to 13 U.S. Surveillance Epidemiology and End Results (SEER) sites from 1973 to 2000 (N = 72,700). The mean age ± SD at diagnosis among 466 PACGENE probands and 670 affected relatives was 64.1 ± 11.8 and was 65.4 ± 11.6 for the subset of 369 FPC probands and 429 relatives. Both samples were significantly younger than the mean age at diagnosis in the SEER population (70.0 ± 12.1 years; differences in curves versus SEER, P < 0.001). Age at diagnosis (excluding probands) in FPC kindreds does not decrease with increasing number of affected individuals. In our sample, younger age at diagnosis was observed whether we grouped probands by recruitment sites that predominantly recruited through high-risk referrals, or through screening all pancreatic cancer patients for family history. Linkage studies are ongoing. The PACGENE Consortium will be a valuable family-based resource that will greatly enhance genetic epidemiology research in pancreatic cancer. (Cancer Epidemiol Biomarkers Prev 2006;15(4):704–10)
Bladder Tumor Contains Higher N7-Methylguanine Levels in DNA than Adjacent Normal Bladder Epithelium
Authors: Saad Abir A. , O'Connor Peter J. , Mostafa Mostafa H. , Metwalli Nabila E. , Cooper Donald P. , Margison Geoffrey P. , Povey Andrew C.
Published: April 2006

Schistosoma haematobium–infected patients are more likely to develop bladder cancer and be more exposed to carcinogenic N-nitroso compounds than uninfected patients. As N7-methylguanine is a marker of exposure to methylating agents of this type, we have measured N7-methyldeoxyguanosine 3′-monophosphate (N7-MedGp) by 32P postlabeling. DNA was isolated from 42 paired normal and tumor tissue of Egyptians with bladder cancer. N7-MedGp was detected in DNA from 93% of the tumors and 74% of the normal bladder tissue samples. Adduct levels were highly variable and ranged from 0.04 to 6.4 and from 0.02 to 0.72 μmol/mol deoxyguanosine 3′-monophosphate (dGp) in tumor and normal DNA, respectively. N7-MedGp levels in normal and tumor DNA were highly correlated with one another (P = 0.007). The mean difference (95% confidence interval) in adduct levels between tumor and normal DNA was 0.21 (0.13-0.32) μmol/mol dGp and this was statistically significant (P < 0.001). The adduct ratio (tumor DNA/normal DNA) varied between 0.2 and 136 (median, 4.6). N7-MedGp levels were not associated with gender, age, or the presence of schistosomiasis. However, lower N7-MedGp levels were found in normal DNA from individuals lacking the GSTM1 gene (P = 0.03) but not the GSTT1 gene or in subjects with the Ile105Val GSTP1 polymorphism. These results show that exposure to methylating agents is widespread and suggest that such exposure may play a role both in tumor initiation and progression. (Cancer Epidemiol Biomarkers Prev 2006;15(4):740–3)
Polymorphisms in Polycyclic Aromatic Hydrocarbon Metabolism and Conjugation Genes, Interactions with Smoking and Prostate Cancer Risk
Authors: Nock Nora L. , Liu Xin , Cicek Mine S. , Li Li , Macarie Flavius , Rybicki Benjamin A. , Plummer Sarah J. , MacLennan Gregory T. , Casey Graham , Witte John S.
Published: April 2006

The relationship between cigarette smoking and prostate cancer remains unclear. Any potential association may depend on the individuals' ability to metabolize and detoxify cigarette carcinogens—such as polycyclic aromatic hydrocarbons. To investigate this, we studied the association between prostate cancer and smoking, as well as the main and modifying effects of functional polymorphisms in genes that metabolize polycyclic aromatic hydrocarbons (CYP1A1 Ile462Val, microsomal epoxide hydrolase His139Arg) and detoxify reactive derivatives (GSTM1 null deletion, GSTT1 null deletion, GSTP1 Ile105Val and Ala114Val) using a family-based case-control design (439 prostate cancer cases and 479 brother controls). Within the entire study population, there were no main effects for smoking or any of the polymorphisms. However, the nondeleted GSTM1 allele was inversely associated with prostate cancer [odds ratio (OR), 0.50; 95% confidence interval (95% CI), 0.26-0.94] among men with less aggressive disease (Gleason score < 7 and clinical tumor stage < T2c) and positively associated (OR, 1.68; 95% CI, 1.01-2.79) with prostate cancer in men with more aggressive disease (Gleason score ≥ 7 or clinical tumor stage ≥ T2c). We also found a statistically significant negative multiplicative interaction between the GSTM1 nondeleted allele and heavy smoking (> 20 pack-years) in the total study population (P = 0.01) and in Caucasians (P = 0.01). Among Caucasians, heavy smoking increased prostate cancer risk nearly 2-fold in those with the GSTM1 null genotype (OR, 1.73; 95% CI, 0.99-3.05) but this increased risk was not observed in heavy smokers who carried the GSTM1 nondeleted allele (OR, 0.95; 95% CI, 0.53-1.71). Our results highlight the importance of considering genetic modifiers of carcinogens when evaluating smoking in prostate cancer. (Cancer Epidemiol Biomarkers Prev 2006;15(4):765–61)