bluuebunny/crossref_metadata_2025 huggingface dataset:
The Death-Associated Protein Kinases: Structure, Function, and Beyond
Authors: Bialik Shani , Kimchi Adi
Published: February 2006

Death-associated protein kinase (DAPk) is the founding member of a newly classified family of Ser/Thr kinases, whose members not only possess significant homology in their catalytic domains, but also share cell death–associated functions. The realization that DAPk is a tumor suppressor gene, whose expression is lost in multiple tumor types, has spurred a flurry of interest in the kinase family and produced an impressive body of literature concerning its function, regulation, and connection to disease. The DAPk family has been linked to several cell death–related signaling pathways, and functions other than cell death have also been proposed. This review presents a thorough structural analysis of the kinases, discusses methods of regulation, clarifies their cellular targets and functions, and shows how these functions are integrated. Although many gaps in our knowledge still remain, the data generated to date can be combined to delineate a place for the DAPk family within the general cell death-signaling network.
LKB1-Dependent Signaling Pathways
Authors: Alessi Dario R. , Sakamoto Kei , Bayascas Jose R.
Published: February 2006

This review focuses on remarkable recent findings concerning the mechanism by which the LKB1 protein kinase that is mutated in Peutz-Jeghers cancer syndrome operates as a tumor suppressor. We discuss evidence that the cellular localization and activity of LKB1 is controlled through its interaction with a catalytically inactive protein resembling a protein kinase, termed STRAD, and an armadillo repeat-containing protein, named mouse protein 25 (MO25). The data suggest that LKB1 functions as a tumor suppressor by not only inhibiting proliferation, but also by exerting profound effects on cell polarity and, most unexpectedly, on the ability of a cell to detect and respond to low cellular energy levels. Genetic and biochemical findings indicate that LKB1 exerts its effects by phosphorylating and activating 14 protein kinases, all related to the AMP-activated protein kinase. The work described in this review shows how a study of an obscure cancer syndrome can uncover new and important regulatory pathways, relevant to the understanding of multiple human diseases.
Cytosolic potassium controls CFTR deactivation in human sweat duct
Authors: Reddy M. M. , Quinton P. M.
Published: February 2006

Absorptive epithelial cells must admit large quantities of salt (NaCl) during the transport process. How these cells avoid swelling to protect functional integrity in the face of massive salt influx is a fundamental, unresolved problem. A special preparation of the human sweat duct provides critical insights into this crucial issue. We now show that negative feedback control of apical salt influx by regulating the cystic fibrosis transmembrane conductance regulator (CFTR) Cl− channel activity is key to this protection. As part of this control process, we report a new physiological role of K+ in intracellular signaling and provide the first direct evidence of acute in vivo regulation of CFTR dephosphorylation activity. We show that cytosolic K+ concentration ([K+]c) declines as a function of increasing cellular NaCl content at the onset of absorptive activity. Declining [K+]c cause parallel deactivation of CFTR by dephosphorylation, thereby limiting apical influx of Cl− (and its co-ion Na+) until [K+]c is stabilized. We surmise that [K+]c stabilizes when Na+ influx decreases to a level equal to its efflux through the basolateral Na+-K+ pump thereby preventing disruptive changes in cell volume.
Cross bridges account for only 20% of total ATP consumption during submaximal isometric contraction in mouse fast-twitch skeletal muscle
Authors: Zhang Shi-Jin , Andersson Daniel C. , Sandström Marie E. , Westerblad Håkan , Katz Abram
Published: February 2006

It is generally believed that cross bridges account for >50% of the total ATP consumed by skeletal muscle during contraction. We investigated the effect of N-benzyl- p-toluene sulfonamide (BTS), an inhibitor of myosin ATPase, on muscle force production and energy metabolism under near-physiological conditions (50-Hz stimulation frequency at 30°C results in 35% of maximal force). Extensor digitorum longus muscles from mice were isolated and stimulated to perform continuous isometric tetanic contractions. Metabolites of energy metabolism were analyzed with fluorometric techniques. ATP turnover was estimated from the changes in phosphocreatine (PCr), ATP, and lactate (−2ΔATP − ΔPCr + [1.5Δlactate]). During contractions (2–10 s), BTS decreased force production to ∼5% of control. Under these conditions, BTS inhibited ATP turnover by only 18–25%. ATP turnover decreased markedly and similarly with and without BTS as the duration of contraction progressed. In conclusion, cross bridges (i.e., actomyosin ATPase) account for only a small fraction (∼20%) of the ATP consumption during contraction in mouse fast-twitch skeletal muscle under near-physiological conditions, suggesting that ion pumping is the major energy-consuming process.
Channel phosphorylation and modulation of L-type Ca2+ currents by cytosolic Mg2+ concentration
Authors: Wang Min , Berlin Joshua R.
Published: February 2006

Previous studies have shown that inhibition of L-type Ca2+ current ( ICa) by cytosolic free Mg2+ concentration ([Mg2+]i) is profoundly affected by activation of cAMP-dependent protein kinase pathways. To investigate the mechanism underlying this counterregulation of ICa, rat cardiac myocytes and tsA201 cells expressing L-type Ca2+ channels were whole cell voltage-clamped with patch pipettes in which [Mg2+] ([Mg2+]p) was buffered by citrate and ATP. In tsA201 cells expressing wild-type Ca2+ channels (α1C/β2A/α2δ), increasing [Mg2+]p from 0.2 mM to 1.8 mM decreased peak ICa by 76 ± 4.5% ( n = 7). Mg2+-dependent modulation of ICa was also observed in cells loaded with ATP-γ-S. With 0.2 mM [Mg2+]p, manipulating phosphorylation conditions by pipette application of protein kinase A (PKA) or phosphatase 2A (PP2A) produced large changes in ICa amplitude; however, with 1.8 mM [Mg2+]p, these same manipulations had no significant effect on ICa. With mutant channels lacking principal PKA phosphorylation sites (α1C/S1928A/β2A/S478A/S479A/α2δ), increasing [Mg2+]p had only small effects on ICa. However, when channel open probability was increased by α1C-subunit truncation (α1CΔ1905/β2A/S478A/S479A/α2δ), increasing [Mg2+]p greatly reduced peak ICa. Correspondingly, in myocytes voltage-clamped with pipette PP2A to minimize channel phosphorylation, increasing [Mg2+]p produced a much larger reduction in ICa when channel opening was promoted with BAY K8644. These data suggest that, around its physiological concentration range, cytosolic Mg2+ modulates the extent to which channel phosphorylation regulates ICa. This modulation does not necessarily involve changes in channel phosphorylation per se, but more generally appears to depend on the kinetics of gating induced by channel phosphorylation.
Activation of hypoxia-inducible factor 1 during macrophage differentiation
Authors: Oda Tomoyuki , Hirota Kiichi , Nishi Kenichiro , Takabuchi Satoshi , Oda Seiko , Yamada Hiroko , Arai Toshiyuki , Fukuda Kazuhiko , Kita Toru , Adachi Takehiko , Semenza Gregg L. , Nohara Ryuji
Published: February 2006

Monocytes/macrophages of the myeloid lineage are the main cellular effectors of innate immunity. Hypoxia-inducible factor 1 (HIF-1) is essential for myeloid cell activation in response to inflammatory stimuli. However, it has not been established whether HIF-1 activity is induced during differentiation from monocyte to macrophage. We demonstrate that macrophage differentiation of THP-1 cells or monocytes from peripheral blood induces increased expression of both HIF-1α and HIF-1β as well as increased HIF-1 transcriptional activity leading to increased expression of HIF-1 target genes. The increased HIF-1 activity in differentiated THP-1 cells resulted from the combined effect of increased HIF-1α mRNA levels and increased HIF-1α protein synthesis. Differentiation-induced HIF-1α protein and mRNA and HIF-1-dependent gene expression was blocked by treating cells with an inhibitor of the protein kinase C or MAP kinase signaling pathway. THP-1 cell differentiation was also associated with increased phosphorylation of the translational regulatory proteins p70 S6 kinase, S6 ribosomal protein, eukaryotic initiation factor 4E, and 4E binding protein 1, thus providing a possible mechanism for the modulation of HIF-1α protein synthesis. RNA interference studies demonstrated that HIF-1α is dispensable for macrophage differentiation but is required for functional maturation.
Bax inhibition protects against free fatty acid-induced lysosomal permeabilization
Authors: Feldstein Ariel E. , Werneburg Nathan W. , Li ZhengZheng , Bronk Steven F. , Gores Gregory J.
Published: February 2006

Lysosomal permeabilization is a key feature of hepatocyte lipotoxicity, yet the mechanisms mediating this critical cellular event are unclear. This study examined the mechanisms involved in free fatty acid (FFA)-induced lysosomal permeabilization and the role of Bax, a Bcl-2 family member, in this event. Exposure of liver cells to palmitate induced Bax activation and translocation to lysosomes. Studies to suppress Bax activation either by pharmacological approaches or small interfering-RNA-mediated inhibition of Bax expression showed that lysosomal permeabilization is Bax dependent. In addition, palmitate treatment resulted in a significant decrease in Bcl-XL, a Bax antagonist. Moreover, forced Bcl-XL expression blocked lysosomal permeabilization. Lysosomal permeabilization by FFA was ceramide and caspase independent. Finally, paradigms that inhibit lysosomal permeabilization also reduced apoptosis. In conclusion, these data strongly support a regulatory role for Bax in FFA-mediated lysosomal permeabilization and subsequent cell death.
Prostanoids contribute to cutaneous active vasodilation in humans
Authors: McCord Gregg R. , Cracowski Jean-Luc , Minson Christopher T.
Published: February 2006

The specific mechanisms by which skin blood flow increases in response to a rise in core body temperature via cutaneous active vasodilation are poorly understood. The primary purpose of this study was to determine whether the cyclooxygenase (COX) pathway contributes to active vasodilation during whole body heat stress ( protocol 1; n = 9). A secondary goal was to verify that the COX pathway does not contribute to the cutaneous hyperemic response during local heating ( protocol 2; n = 4). For both protocols, four microdialysis fibers were placed in forearm skin. Sites were randomly assigned and perfused with 1) Ringer solution (control site); 2) ketorolac (KETO), a COX-1/COX-2 pathway inhibitor; 3) NG-nitro-l-arginine methyl ester (l-NAME), a nitric oxide synthase inhibitor; and 4) a combination of KETO and l-NAME. During the first protocol, active vasodilation was induced using whole body heating with water-perfused suits. The second protocol used local heaters to induce a local hyperemic response. Red blood cell flux (RBC flux) was indexed at all sites using laser-Doppler flowmetry, and cutaneous vascular conductance (CVC; RBC flux/mean arterial pressure) was normalized to maximal vasodilation at each site. During whole body heating, CVC values at sites perfused with KETO (43 ± 9% CVCmax), l-NAME (35 ± 9% CVCmax), and combined KETO/l-NAME (22 ± 8% CVCmax) were significantly decreased with respect to the control site (59 ± 7% CVCmax) ( P < 0.05). Additionally, CVC at the combined KETO/l-NAME site was significantly decreased compared with sites infused with KETO or l-NAME alone ( P < 0.05). In the second protocol, the hyperemic response to local heating did not differ between the control site and KETO site or between the l-NAME and KETO/l-NAME site. These data suggest that prostanoids contribute to active vasodilation, but do not play a role during local thermal hyperemia.
Does experimental pain response vary across the menstrual cycle? A methodological review
Authors: Sherman Jeffrey J. , LeResche Linda
Published: February 2006

The findings on sex differences in human experimental pain research are inconsistent. One possible factor contributing to the inconsistent findings is the female hormonal cycle, as hormone levels may affect pain sensitivity. A number of studies suggest that women's responses to experimentally evoked pain vary across the menstrual cycle. However, at least an equal number of studies suggest a lack of variability. The purpose of this article is to review the literature with emphasis on what we believe could be the reasons for the inconsistent findings, namely, differences in populations sampled, timing of experimental sessions across the menstrual cycle, and nomenclature used to identify the time (phases) in the cycle when measurements were done, nature of the pain stimuli chosen, and outcomes measured. These inconsistencies and other methodological problems associated with most experimental pain studies make it difficult to draw inferences from this literature. For the science to improve, replication of significant findings using standardized timing of sessions, pain stimulus procedures, outcomes, and hormonal assessment is necessary.
Enhanced sympathetic outflow and decreased baroreflex sensitivity are associated with intermittent hypoxia-induced systemic hypertension in conscious rats
Authors: Lai C. J. , Yang C. C. H. , Hsu Y. Y. , Lin Y. N. , Kuo T. B. J.
Published: February 2006

Long-term exposure to intermittent hypoxia (IH), such as that occurring in association with sleep apnea, may result in systemic hypertension; however, the time course changes in arterial pressure, autonomic functions, and baroreflex sensitivity are still unclear. We investigated the changes in cardiovascular neural regulations during the development of chronic IH-induced hypertension in rats. Sprague-Dawley rats were exposed to repetitive 1.25-min cycles (30 s of N2 + 45 s of 21% O2) of IH or room air (RA) for 6 h/day during light phase (10 AM-4 PM) for 30 days. Arterial pressure was measured daily using the telemetry system during RA breathing. The mean arterial pressure (MAP) and interpulse interval (PPI) signals were then used to assess the autonomic functions and spontaneous baroreflex sensitivity by auto- and cross-spectral analysis, respectively. Stable MAP, low-frequency power of MAP (BLF), and low-frequency power (LF)-to-high frequency power (HF) ratio of PPI (LF/HF) were significantly higher in IH-exposed rats, compared with those of RA-exposed rats. Elevation of the MAP, BLF, LF/HF, and minute ventilation started 5 days after IH exposure and lasted until the end of the 30-day observation period. Additionally, IH-exposed rats had significant lower slope of MAP-PPI linear regression (under a successively descending and ascending) and magnitude of MAP-PPI transfer function (at frequency ranges of 0.06–0.6 Hz or 0.6–2.4 Hz) after IH exposure for 17 days. However, RA-exposed rats did not exhibit these changes. The results of this study indicate that chronic IH-induced hypertension is associated with a facilitation of cardiovascular sympathetic outflow and inhibition of baroreflex sensitivity in conscious rats.
Scaling of maximal oxygen uptake by lower leg muscle volume in boys and men
Authors: Tolfrey Keith , Barker Alan , Thom Jeanette M. , Morse Christopher I. , Narici Marco V. , Batterham Alan M.
Published: February 2006

The aim of this study was to critically examine the influence of body size on maximal oxygen uptake (V̇o2 max) in boys and men using body mass (BM), estimated fat-free mass (FFM), and estimated lower leg muscle volume (Vol) as the separate scaling variables. V̇o2 max and an in vivo measurement of Vol were assessed in 15 boys and 14 men. The FFM was estimated after percentage body fat had been predicted from population-specific skinfold measurements. By using nonlinear allometric modeling, common body size exponents for BM, FFM, and Vol were calculated. The point estimates for the size exponent (95% confidence interval) from the separate allometric models were: BM 0.79 (0.53–1.06), FFM 1.00 (0.78–1.22), and Vol 0.64 (0.40–0.88). For the boys, substantial residual size correlations were observed for V̇o2 max/BM0.79 and V̇o2 max/FFM1.00, indicating that these variables did not correctly partition out the influence of body size. In contrast, scaling by Vol0.64 led to no residual size correlation in boys or men. Scaling by BM is confounded by heterogeneity of body composition and potentially substantial differences in the mass exponent between boys and men. The FFM is precluded as an index of involved musculature because Vol did not represent a constant proportion of FFM [Vol∝FFM1.45 (95% confidence interval, 1.13–1.77)] in the boys (unlike the men). We conclude that Vol, as an indicator of the involved muscle mass, is the most valid allometric denominator for the scaling of V̇o2 max in a sample of boys and men heterogeneous for body size and composition.
Form and Function of on-off Amacrine Cells in the Amphibian Retina
Authors: Miller Robert F. , Staff Nathan P. , Velte Toby J.
Published: February 2006

on-off amacrine cells were studied with whole cell recording techniques and intracellular staining methods using intact retina-eyecup preparations of the tiger salamander ( Ambystoma tigrinum) and the mudpuppy ( Necturus maculosus). Morphological characterization of these cells included three-dimensional reconstruction methods based on serial optical sections obtained with a confocal microscope. Some cells had their detailed morphology digitized with a computer-assisted tracing system and converted to compartmental models for computer simulations. The dendrites of on-off amacrine cells have spines and numerous varicosities. Physiological recordings confirmed that on-off amacrine cells generate both large- and small-amplitude impulses attributed, respectively, to somatic and dendritic generation sites. Using a multichannel model for impulse generation, computer simulations were carried out to evaluate how impulses are likely to propagate throughout these structures. We conclude that the on-off amacrine cell is organized with multifocal dendritic impulse generating sites and that both dendritic and somatic impulse activity contribute to the functional repertoire of these interneurons: locally generated dendritic impulses can provide regional activation, while somatic impulse activity results in rapid activation of the entire dendritic tree.
Endogenous Activation of Adenosine A1 Receptors, but Not P2X Receptors, During High-Frequency Synaptic Transmission at the Calyx of Held
Authors: Wong Adrian Y. C. , Billups Brian , Johnston Jamie , Evans Richard J. , Forsythe Ian D.
Published: February 2006

Activation of presynaptic receptors plays an important role in modulation of transmission at many synapses, particularly during high-frequency trains of stimulation. Adenosine-triphosphate (ATP) is coreleased with several neurotransmitters and acts at presynaptic sites to reduce transmitter release; such presynaptic P2X receptors occur at inhibitory and excitatory terminals in the medial nucleus of the trapezoid body (MNTB). We have investigated the mechanism of purinergic modulation during high-frequency repetitive stimulation at the calyx of Held synapse. Suppression of calyceal excitatory postsynaptic currents (EPSCs) by ATP and ATPγS (100 μM) was mimicked by adenosine application and was blocked by DPCPX (10 μM), indicating mediation by adenosine A1 receptors. DPCPX enhanced EPSC amplitudes during high-frequency synaptic stimulation, suggesting that adenosine has a physiological role in modulating transmission at the calyx. The Luciferin-Luciferase method was used to probe for endogenous ATP release (at 37°C), but no release was detected. Blockers of ectonucleotidases also had no effect on endogenous synaptic depression, suggesting that it is adenosine acting on A1 receptors, rather than degradation of released ATP, which accounts for presynaptic purinergic suppression of synaptic transmission during physiological stimulus trains at this glutamatergic synapse.
Growth Hormone Enhances Excitatory Synaptic Transmission in Area CA1 of Rat Hippocampus
Authors: Mahmoud Ghada S. , Grover Lawrence M.
Published: February 2006

The hippocampus produces growth hormone (GH) and contains GH receptors, suggesting a potential role for GH signaling in the regulation of hippocampal function. In agreement with this possibility, previous investigations have found altered hippocampal function and hippocampal-dependent learning and memory after chronic GH administration or deficiency. In this study we applied GH to in vitro rat hippocampal brain slices, to determine whether GH has short-term effects on hippocampal function in addition to previously documented chronic effects. We found that GH enhanced both AMPA- and NMDA-receptor–mediated excitatory postsynaptic potentials (EPSPs) in hippocampal area CA1, but did not alter GABAA-receptor–mediated inhibitory synaptic transmission. GH enhancement of excitatory synaptic transmission was gradual, requiring 60–70 min to reach maximum, and occurred without any change in paired-pulse facilitation, suggesting a possible postsynaptic site of action. In CA1 pyramidal neurons, GH enhancement of EPSPs was correlated with significant hyperpolarization and decreased input resistance. GH enhancement of EPSPs required Janus kinase 2 (JAK2), phosphatidylinositol-3 (PI3) kinase, mitogen-activated protein (MAP) kinase kinase (MEK), and synthesis of new proteins. Although PI3 kinase and MEK were required for initiation of GH effects on excitatory synaptic transmission, they were not required for maintained enhancement of EPSPs. GH treatment and tetanus-induced long-term potentiation were mutually occluding, suggesting a common mechanism or mechanisms in both forms of synaptic enhancement. Our results demonstrate that GH has powerful short-term effects on hippocampal function, and extend the timescale for potential roles of GH in regulating hippocampal function and hippocampal-dependent behaviors.
Middle Ear Forward and Reverse Transmission in Gerbil
Authors: Dong Wei , Olson Elizabeth S.
Published: February 2006

The middle ear transmits environmental sound to the inner ear. It also transmits acoustic energy sourced within the inner ear out to the ear canal, where it can be detected with a sensitive microphone as an otoacoustic emission. Otoacoustic emissions are an important noninvasive measure of the condition of sensory hair cells and to use them most effectively one must know how they are shaped by the middle ear. In this contribution, forward and reverse transmissions through the middle ear were studied by simultaneously measuring intracochlear pressure in scala vestibuli near the stapes and ear canal pressure. Measurements were made in gerbil, in vivo, with acoustic two-tone stimuli. The forward transmission pressure gain was about 20–25 dB, with a phase–frequency relationship that could be fit by a straight line, and was thus characteristic of a delay, over a wide frequency range. The forward delay was about 32 μs. The reverse transmission pressure loss was on average about 35 dB, and the phase–frequency relationship was again delaylike with a delay of about 38 μs. Therefore to a first approximation the middle ear operates similarly in the forward and reverse directions. The observation that the amount of pressure reduction in reverse transmission was greater than the amount of pressure gain in forward transmission suggests that complex motions of the tympanic membrane and ossicles affect reverse more than forward transmission.
A Continuum Mechanical Model of Mechanoreceptive Afferent Responses to Indented Spatial Patterns
Authors: Sripati Arun P. , Bensmaia Sliman J. , Johnson Kenneth O.
Published: February 2006

Information about the spatial structure of tactile stimuli is conveyed by slowly adapting type 1 (SA1) and rapidly adapting (RA) afferents innervating the skin. Here, we investigate how the spatial properties of the stimulus shape the afferent response. To that end, we present an analytical framework to characterize SA1 and RA responses to a wide variety of spatial patterns indented into the skin. This framework comprises a model of the tissue deformation produced by any three-dimensional indented spatial pattern, along with an expression that converts the deformation at the receptor site into a neural response. We evaluated 15 candidate variables for the relevant receptor deformation and found that physical quantities closely related to local membrane stretch were most predictive of the observed afferent responses. The main outcome of this study is an accurate working model of SA1 and RA afferent responses to indented spatial patterns.
Sex-specific telomere length profiles and age-dependent erosion dynamics of individual chromosome arms in humans
Authors: Mayer S. , Brüderlein S. , Perner S. , Waibel I. , Holdenried A. , Ciloglu N. , Hasel C. , Mattfeldt T. , Nielsen K.V. , Möller P.
Published: February 2006

During aging, telomeres are gradually shortened, eventually leading to cellular senescence. By T/C-FISH (telomere/centromere-FISH), we investigated human telomere length differences on single chromosome arms of 205 individuals in different age groups and sexes. For all chromosome arms, we found a linear correlation between telomere length and donor age. Generally, males had shorter telomeres and higher attrition rates. Every chromosome arm had its individual age-specific telomere length and erosion pattern, resulting in an unexpected heterogeneity in chromosome- specific regression lines. This differential erosion pattern, however, does not seem to be accidental, since we found a correlation between average telomere length of single chromosome arms in newborns and their annual attrition rate. Apart from the above-mentioned sex-specific discrepancies, chromosome arm-specific telomere lengths were strikingly similar in men and women. This implies a mechanism that arm specifically regulates the telomere length independent of gender, thus leading to interchromosomal telomere variations.
Assignment of the NAD-dependent deacetylase sirtuin 5 gene (SIRT5) to human chromosome band 6p23 by in situ hybridization
Authors: Mahlknecht U. , Ho A.D. , Letzel S. , Voelter-Mahlknecht S.
Published: February 2006

Sirtuin 5 (SIRT5) is a nicotinamide adenine dinucleotide (NAD+)-dependent deacetylase and belongs to the Silent information regulator 2 (Sir2) family of sirtuin histone deacetylases (HDACs), which play a central role in epigenetic gene silencing, DNA repair and recombination, cell-cycle, microtubule organization, and in the regulation of aging. We have isolated and characterized the human SIRT5 genomic sequence, which spans a region of 28,182 bp and which has one single genomic locus. Human SIRT5 consists of eight exons and is found in two isoforms, which encode a 310 aa and a 299 aa protein, respectively. Human SIRT5 is most predominantly expressed in heart muscle cells and in lymphoblasts. Fluorescence in situ hybridization analysis localized the human SIRT5 gene to chromosome 6p23.
Different breakage-prone regions on chromosome 1 detected in t(11;14)-positive mantle cell lymphoma cell lines and multiple myeloma cell lines are associated with different tumor progession-related mechanisms
Authors: Rudolph C. , Liehr T. , Steinemann D. , Emura M. , Daibata M. , Matsuo Y. , Emi N. , Abe M. , Lai R. , Mrasek K. , Claussen U. , Schlegelberger B.
Published: February 2006

To better define secondary aberrations that occur in addition to translocation t(11;14)(q13;q32) in mantle cell lymphomas (MCL) and in multiple myelomas (MM), seven t(11;14)-positive MCL cell lines and four t(11;14)-positive MM cell lines were analysed by fluorescence R-banding and spectral karyotyping (SKY). Compared with published data obtained by G-banding, most chromosome aberrations were redefined or further specified. Furthermore, several additional chromosome aberrations were identified. Thus, these cytogenetically well defined t(11;14)-positive MCL and MM cell lines may be useful tools for the identification and characterization of genes that might be involved in the pathogenesis of MCL and MM, respectively. Since MCL and MM were found to have different alterations of chromosome 1, these were investigated in more detail by fluorescence in situ hybridization (FISH) and multicolor banding (MCB) analyses. The most frequently altered and deletion-prone loci in MCL cell lines were regions 1p31 and 1p21. In contrast, breakpoints in MM cell lines most often involved the heterochromatic regions 1p12→p11, and the subcentromeric regions 1q12 and 1q21. These data are in accordance with previously published data of primary lymphomas. Our findings may indicate that different pathways of clonal evolution are involved in these morphologically distinct lymphomas harboring an identical primary chromosome aberration, t(11;14).
Sperm nuclei analysis of 1/29 Robertsonian translocation carrier bulls using fluorescence in situ hybridization
Authors: Bonnet-Garnier A. , Pinton A. , Berland H.M. , Khireddine B. , Eggen A. , Yerle M. , Darré R. , Ducos A.
Published: February 2006

In 1964, Gustavsson and Rockborn first described the 1/29 Robertsonian translocation in cattle. Since then, several studies have demonstrated the negative effect of this particular chromosomal rearrangement on the fertility of carrier animals. During the last decade, meiotic segregation patterns have been studied on human males carrying balanced translocations using FISH on decondensed sperm nuclei. In this work, we have applied the ‘Sperm-FISH’ technique to determine the chromosomal content of spermatozoa from two bulls heterozygous for the 1/29 translocation and one normal bull (control). 5425 and 2702 sperm nuclei were scored, respectively, for the two heterozygous bulls, using whole chromosome painting probes of chromosomes 1 and 29. Very similar proportions of normal (or balanced) spermatozoa resulting from alternate segregation were observed (97.42% and 96.78%). For both heterozygous bulls, the proportions of nullisomic and disomic spermatozoa did not follow the theoretical 1:1 ratio. Indeed, proportions of nullisomic spermatozoa were higher than those of disomic sperma tozoa (1.40% vs 0.09% (bull 1) and 1.29% vs 0.15% (bull 2) for BTA1, and 0.65% vs 0.40% (bull 1) and 1.11% vs 0.63% (bull 2) for BTA29). The average frequencies of disomic and diploid spermatozoa in the normal bull were 0.11% and 0.05%, respectively.
Linkage mapping and physical localization of the major histocompatibility complex region of the marsupial Monodelphis domestica
Authors: Gouin N. , Deakin J.E. , Miska K.B. , Miller R.D. , Kammerer C.M. , Graves J.A.M. , VandeBerg J.L. , Samollow P.B.
Published: February 2006

We used genetic linkage mapping and fluorescence in situhybridization (FISH) to conduct the first analysis of genic organization and chromosome localization of the major histocompatibility complex (MHC) of a marsupial, the gray, short-tailed opossum Monodelphis domestica. Family based linkage analyses of two M. domestica MHC Class I genes (UA1, UG) and three MHC Class II genes (DAB, DMA, and DMB) revealed that these genes were tightly linked and positioned in the central region of linkage group 3 (LG3). This cluster of MHC genes was physically mapped to the centromeric region of chromosome 2q by FISH using a BAC clone containing the UA1 gene. An interesting finding from the linkage analyses is that sex-specific recombination rates were virtually identical within the MHC region. This stands in stark contrast to the genome-wide situation, wherein males exhibit approximately twice as much recombination as females, and could have evolutionary implications for maintaining equality between males and females in the ability to generate haplotype diversity in this region. These analyses also showed that three non-MHC genes that flank the MHC region on human chromosome 6, myelin oligodendrocyte glycoprotein (MOG), bone morphogenetic protein 6 (BMP6), and prolactin (PRL), are split among two separate linkage groups (chromosomes) in M. domestica. Comparative analysis with eight other vertebrate species suggests strong conservation of the BMP6–PRL synteny among birds and mammals, although the BMP6–PRL–MHC–ME1 synteny is not conserved.
Dilated Cardiomyopathy Associated with Toluene Abuse
Authors: Vural Mutlu , Ogel Kultegin
Published: February 2006

The use of paint thinner and glue to achieve an euphoric state has been associated with serious social and health problems in children and young adults. We present the case of a 21-year-old man with dilated cardiomyopathy occurring following abuse of paint thinner and glue containing toluene as main compound. After cessation of toluene abuse, the patient recovered rapidly and completely. Because of the increasing prevalence of toluene abuse, harmful effects of this volatile agent on the heart are also discussed.
Complete Clinical Remission and Disappearance of Liver Metastases after Treatment with Somatostatin Analogue in a 40-Year-Old Woman with a Malignant Insulinoma Positive for Somatostatin Receptors Type 2
Authors: Romeo Stefano , Milione Massimo , Gatti Alessandra , Fallarino Mara , Corleto Vito , Morano Susanna , Baroni Marco Giorgio
Published: February 2006

Insulinoma is the most common pancreatic endocrine tumor, accounting for 40% of all pancreatic functional neoplasm, and is characterized by hypersecretion of insulin and hypoglycemia. Elective treatment for insulinomas is surgical enucleation. Medical therapy with diazoxide, followed by somatostatin analogues in some cases, may be necessary to treat the hypoglycemic symptoms. We report a case of a patient affected by metastatic insulinoma with severe hypoglycemia. After surgery, histopathology confirmed the presence of a malignant insulinoma with multiple metastases in the liver. Due to the persistence of hypoglycemia, the patient was started on octreotide LAR treatment, which determined a complete clinical remission with regression of the metastatic lesions in the liver after one year. Repeated CT scans 2 and 3 years after surgery confirmed the remission. To our knowledge, the complete regression of the disease in insulinomas treated with long-standing somatostatin analogue therapy has never been reported. Immunohistochemical analysis in tissue specimens showed a strong membrane immunoreactivity for somatostatin receptors type 2 (SSTR2) in both the primary nodule and the metastases. The capacity of somatostatin analogues to negatively regulate cell proliferation through indirect and direct mechanisms has been experimentally demonstrated. Furthermore, SSTR2 activation may exert pro-apoptotic effects in neoplastic cells. Thus, both mechanisms may have been responsible of the remission of the disease in this patient. This case underlies the potential impact of the treatment of pancreatic insulinomas with somatostatin analogues, and, if confirmed, the usefulness of SSTR determination in these neoplastic specimens.
Mild Cognitive Impairment: Deficits in Cognitive Domains Other than Memory
Authors: Ribeiro F. , de Mendonça A. , Guerreiro M.
Published: February 2006

Patients with mild cognitive impairment (MCI) typically present with memory complaints, but may have mild deficits in other cognitive domains. We compared the neuropsychological profiles of a series of consecutive MCI patients (n = 116) with a control group of healthy elderly subjects (n = 63). The presence of a memory deficit on delayed recall was consistent in the MCI sample, as it was an inclusion criterion in the study. Impairment on immediate recall was present in 62.6% of the patients on paragraph recall of the logical memory test and in 63.1% of the patients on the word paired-associate learning test. Remarkably, patients with MCI frequently had deficits in cognitive domains beyond memory. As much as 68.7% of the patients had deficits in temporal orientation, 30.2% had deficits in semantic fluency, 33.7% in the Token test, 23.4% in calculation, and 23.9% in motor initiative. If detailed neuropsychological testing is performed, the majority of MCI patients will have deficits in cognitive domains other than memory.
Clinicopathologic Characteristics of Hepatitis C Virus-Associated Intrahepatic Cholangiocarcinoma
Authors: Hai Seikan , Kubo Shoji , Yamamoto Satoshi , Uenishi Takahiro , Tanaka Hiromu , Shuto Taichi , Takemura Shigekazu , Yamazaki Osamu , Hirohashi Kazuhiro
Published: February 2006

Background: Although hepatitis C virus (HCV) infection is a possible pathogenetic factor for intrahepatic cholangiocarcinoma (ICC), clinicopathologic features of ICC patients with HCV infection remain unclear. Patients and Methods: Of 50 patients with ICC treated, 19 were infected with HCV (HCV-positive group) and 38 underwent surgical treatment. Clinicopathologic features and postoperative outcome were compared between patients with and without HCV infection. Results: In 15 patients in the HCV-positive group, ICC was detected during follow-up for chronic hepatitis C. The proportion of patients who underwent curative resection was significantly higher in the HCV-positive than in the HCV-negative group, and tumors were significantly smaller in the HCV-positive than in the HCV-negative group. In the HCV-positive group, tumors were significantly smaller in patients who were followed up for chronic hepatitis C than in patients who were not followed up. Although cumulative survival rates did not differ significantly between groups, prognoses of patients with small ICC were significantly better than those with large ICC. Conclusion: Follow-up for patients with chronic hepatitis C by imaging series at regular intervals is important and provides the possibility to detect a small ICC as well as a hepatocellular carcinoma. Resection should be guided by liver function and the tumor stage in patients with HCV-associated ICC.
External Pancreatic Fistula as a Sequel to Management of Acute Severe Necrotizing Pancreatitis
Authors: Sikora Sadiq S. , Khare Ritu , Srikanth Gadiyaram , Kumar Ashok , Saxena Rajan , Kapoor Vinay K.
Published: February 2006

Background/Aims: External pancreatic fistula (EPF) is a common sequel to surgical or percutaneous intervention for infective complications of acute severe pancreatitis. The present study was aimed at studying the clinical profile, course and outcome of patients with EPF following surgical or percutaneous management of these infective complications. Methods: A retrospective analysis of clinical data of patients with EPF following intervention (surgical or percutaneous) for acute severe pancreatitis managed between January 1989 and April 2002 recorded on a prospective database was done. Univariate analysis of various factors (etiology, imaging findings prior to intervention, fistula characteristics and management) that could predict early closure of fistula was performed. Results: Of 210 patients with acute severe pancreatitis, 43 (20%) patients developed EPF (mean age 38 (range 16–78) years, M:F ratio 5:1) following intervention for infected pancreatic necrosis (n = 23) and pancreatic abscess (n = 20) and constituted the study group. The fistula output was categorized as low (<200 ml), moderate (200–500 ml) and high (>500 ml) in 29 (67%), 11 (26%) and 3 (7%) patients, respectively. Fifteen patients (35%) had morbidity in the form of abscess (n = 5), bleeding (n = 1), pseudoaneurysm (n = 2) and fever with no other focus of infection (n = 7). Spontaneous closure of the fistula occurred in 38 (88%) patients. The average time to closure of fistula was 109 ± 26 (median 70) days. Fistula closed after intervention in 5 patients (2 after endoscopic papillotomy, 1 after fistulojejunostomy and 2 after downsizing the drains). Of the 38 patients with spontaneous closure, 9 (24%) patients developed a pseudocyst after a mean interval of 123 days of which 7 underwent surgical drainage of the cyst. Univariate analysis of various factors (etiology, imaging findings prior to intervention, fistula characteristics and management) failed to identify any factors that could predict early closure of fistula. Conclusions: EPF is a common sequel following intervention in acute severe pancreatitis. The majority of these are low output fistulae and close spontaneously with conservative management. One-fourth of patients with spontaneous closure develop a pseudocyst as a sequel, requiring surgical management.
Can Endoscopic Ultrasonography-Guided Fine-Needle Aspiration Predict Response to Chemoradiation in Non-Small Cell Lung Cancer?
Authors: Varadarajulu Shyam , Eloubeidi Mohamad
Published: February 2006

Background: Accurate prediction of pathologic response to chemoradiation (CHEMO-XRT) has a significant impact on the treatment of patients with non-small cell lung cancer (NSCLC) and mediastinal lymph node (LN) metastasis (N2 disease). Objective: This pilot study evaluates the ability of EUS-FNA to predict pathologic response in LN following CHEMO-XRT in NSCLC patients with N2 disease. Patients and Methods: Retrospective analysis of prospectively collected data on patients with NSCLC and biopsy-proven N2 disease who underwent restaging by EUS following CHEMO-XRT. At restaging, FNA was performed on the same LN, if present, or any other visible LN in the posterior mediastinum. Response to therapy (N0 disease) was defined by either absence of mediastinal LN or residual disease on FNA. Those staged N0 by EUS underwent tumor resection with complete LN dissection. Results: Fourteen patients met the criteria for evaluation. Restaging by EUS suggested disease response in 7 patients and residual disease in 6; tissue yield was unsatisfactory in 1 patient. Eleven of 14 patients in whom mediastinal LN were seen at restaging by EUS underwent FNA: the aspirate was benign in 4, residual disease was found in 6, and an inadequate sample was obtained in 1 patient. In 3 patients no mediastinal LN were evident at EUS. Final diagnosis on the 7 patients in whom EUS suggested N0 disease was established at surgery: EUS was true negative in 6 and false negative in 1. Of the 6 patients with residual disease, 5 underwent palliative CHEMO-XRT and 1 underwent extended tumor resection. The patient in whom tissue sampling was inadequate was found to have residual disease at surgery. The diagnostic accuracy of EUS-FNA for predicting mediastinal response to preoperative CHEMO-XRT was 86%. Conclusions: EUS-FNA appears to qualify as an accurate, safe and minimally invasive diagnostic technique for restaging of mediastinal LN after CHEMO-XRT in NSCLC patients. Given this promising preliminary data, a prospective evaluation is justified.
The procoagulant effects of factor V Leiden may be balanced against decreased levels of factor V and do not reflect in vivo thrombin formation in newborns
Authors: Hyytiäinen Satu , Wartiovaara-Kautto Ulla , Ulander Veli-Matti , Kaaja Risto , Heikinheimo Markku , Petäjä Jari
Published: February 2006

Thrombin regulation in newborns remains incompletely understood.We studied tissue factor-initiated thrombin formation in cord plasma in vitro, and the effects of Factor VLeiden (FVL) heterozygosity on thrombin regulation both in vitro and in vivo in newborns. Pregnant women with known thrombophilia (n=27) were enrolled in the study. Cord blood and venous blood at the age of 14 days were collected from 11 FVL heterozygous newborns (FVL-positive) and from 16 FVL-negative newborns. Prothrombin fragment F1+2 and coagulation factors were measured. Tissue factor-initiated thrombin formation was studied in cord platelet-poor plasma (PPP) of FVL-negative and -positive newborns, and in both PPP and platelet-rich plasma (PRP) of healthy controls. The endogenous thrombin potential (ETP) in cord PPP or PRP was ∼60% of that in adult plasma, while thrombin formation started ∼55% and ∼40% earlier in cord PPP and PRP, respectively. Further, in FVL-positive newborns thrombin formation started significantly earlier than in FVL-negative newborns. Exogenous activated protein C (APC) decreased ETP significantly more in cord than in adult PRP. In FVL-negative cord plasma 5nM APC decreased ETP by 17.4±3.5% (mean±SEM) compared with only 3.5±3.8% in FVL-positive cord plasma (p=0.01). FVL-positive newborns showed similar levels of F1+2 but significantly decreased levels of factor V compared with FVL negative newborns both in cord plasma (FV 0.82±0.07 U/ml vs. 0.98±0.05 U/ml, p=0.03) and at the age of two weeks (FV 1.15±0.04 U/ml vs. 1.32±0.05 U/ml, p=0.03). In conclusion, newborn plasma showed more rapid thrombin formation and enhanced sensitivity to APC compared with adult plasma. FVL conveyed APC resistance and a procoagulant effect in newborn plasma. Lack of elevated F1+2 levels in FVL-positive infants, however, suggested the existence of balancing mechanisms; one could be the observed lower level of factor V in FVL heterozygous newborns.
Gender differences in the expression of erythrocyte aggregation in relation to Bβ-fibrinogen gene polymorphisms in apparently healthy individuals
Authors: Assayag Einor , Bova Irena , Berliner Shlomo , Peretz Hava , Usher Sali , Shapira Itzhak , Bornstein Natan
Published: February 2006

An increased erythrocyte aggregation (EA) is associated with capillary slow flow, tissue hypoxemia and endothelial dysfunction. Fibrinogen is a major determinant in the formation of aggregated red blood cells. It has been suggested that the Bβ-fibrinogen –455G/A polymorphism is associated with erythrocyte hyperaggregability in men with coronary artery disease.The purpose of this study was to investigate the influence of the β-fibrinogen –455G/A polymorphism on erythrocyte aggregation in apparently healthy individuals. Plasma fibrinogen, red blood cell count, serum lipids, erythrocyte sedimentation rate, and the genotype of the Bβ-fibrinogen –455G/A polymorphism were examined in a cohort of 545 apparently healthy individuals and those with atherothrombotic risk factors. A whole blood erythrocyte aggregation test was performed by using a simple slide test and image analysis. In men, EA levels and plasma fibrinogen levels were significantly higher in subjects carrying the –455A allele compared to subjects with the –455 GG genotype.This association did not exist in women carrying the fibrinogen –455A allele.The –455GA/AA men presented significantly higher correlation between the plasma fibrinogen concentrations and EA. This observation raises the prospect of possible change in the functional properties of the –455GA/AA fibrinogen, enhancing its ability to induce EH. This study suggests that the Bβ-fibrinogen –455A allele is related to EH in men only. Putative mechanism could be hyperfibrinogenemia anda functional change in the fibrinogen molecule that alters its ability to interact with red blood cells and supports the aggregability of these cells.