bluuebunny/crossref_metadata_2025 huggingface dataset:
In vitro and in vivo evaluation of NCX 4040 cytotoxic activity in human colon cancer cell lines
Authors: Tesei Anna , Ulivi Paola , Fabbri Francesco , Rosetti Marco , Leonetti Carlo , Scarsella Marco , Zupi Gabriella , Amadori Dino , Bolla Manlio , Zoli Wainer
Published: February 2005

Background

Nitric oxide-releasing nonsteroidal antiinflammatory drugs (NO-NSAIDs) are reported to be safer than NSAIDs because of their lower gastric toxicity. We compared the effect of a novel NO-releasing derivate, NCX 4040, with that of aspirin and its denitrated analog, NCX 4042, in in vitro and in vivo human colon cancer models and investigated the mechanisms of action underlying its antitumor activity.

Methods

In vitro cytotoxicity was evaluated on a panel of colon cancer lines (LoVo, LoVo Dx, WiDr and LRWZ) by sulforhodamine B assay. Cell cycle perturbations and apoptosis were evaluated by flow cytometry. Protein expression was detected by Western blot. In the in vivo experiments, tumor-bearing mice were treated with NCX 4040, five times a week, for six consecutive weeks.

Results

In the in vitro studies, aspirin and NCX 4042 did not induce an effect on any of the cell lines, whereas NCX 4040 produced a marked cytostatic dose-related effect, indicating a pivotal role of the -NO2 group. Furthermore, in LoVo and LRWZ cell lines, we observed caspase-9 and -3-mediated apoptosis, whereas no apoptotic effect was observed after drug exposure in WiDr or LoVo Dx cell lines. In in vivo studies, both NCX 4040 and its parental compound were administered per os. NCX 4040 induced a 40% reduction in tumor weight. Conversely, aspirin did not influence tumor growth at all.

Conclusions

NCX 4040, but not its parental compound, aspirin, showed an in vitro and in vivo antiproliferative activity, indicating its potential usefulness to treat colon cancer.
HIV-1 Tat protein enhances Microtubule polymerization
Authors: de Mareuil Jean , Carre Manon , Barbier Pascale , Campbell Grant R , Lancelot Sophie , Opi Sandrine , Esquieu Didier , Watkins Jennifer D , Prevot Charles , Braguer Diane , Peyrot Vincent , Loret Erwann P
Published: February 2005

Background

HIV infection and progression to AIDS is characterized by the depletion of T cells, which could be due, in part, to apoptosis mediated by the extra-cellular HIV-encoded Tat protein as a consequence of Tat binding to tubulin. Microtubules are tubulin polymers that are essential for cell structure and division. Molecules that target microtubules induce apoptosis and are potent anti-cancer drugs. We studied the effect on tubulin polymerization of three Tat variants: Tat HxB2 and Tat Eli from patients who are rapid progressors (RP) and Tat Oyi from highly exposed but persistently seronegative (HEPS) patients. We compared the effect on tubulin polymerization of these Tat variants and peptides corresponding to different parts of the Tat sequence, with paclitaxel, an anti-cancer drug that targets microtubules.

Results

We show that Tat, and specifically, residues 38–72, directly enhance tubulin polymerization. We demonstrate that Tat could also directly trigger the mitochondrial pathway to induce T cell apoptosis, as shown in vitro by the release of cytochrome c from isolated mitochondria.

Conclusions

These results show that Tat directly acts on microtubule polymerization and provide insights into the mechanism of T cell apoptosis mediated by extra-cellular Tat.
Modulation of Mitochondrial Transition Pore Components by Thyroid Hormone
Authors: Yehuda-Shnaidman Einav , Kalderon Bella , Bar-Tana Jacob
Published: February 2005

Thyroid hormone (TH) modulates metabolic efficiency by controlling the coupling of mitochondrial oxidative phosphorylation. However, its uncoupling mode of action is still enigmatic. Treatment of Jurkat or GH3 cells with T3 is reported here to result in limited, Cyclosporin A-sensitive mitochondrial depolarization, conforming to low conductance gating of the mitochondrial transition pore (MTP). MTP protein components induced by T3 treatment were verified in T3-treated and hypothyroid rat liver as well as in Jurkat cells. T3 treatment resulted in increase in mitochondrial Bax and Bak together with decreased mitochondrial Bcl2. T3-induced mitochondrial depolarization was aborted by overexpression of Bcl2. In contrast to Bax-Bcl2 family proteins, some other MTP components were either not induced by T3 (e.g. voltage-dependent anion channel) or were induced, but were not involved in Cyclosporin A-sensitive MTP gating (e.g. Cyclophilin D and adenine nucleotide translocase-2) Hence, TH-induced mitochondrial uncoupling may be ascribed to low conductance MTP gating mediated by TH-induced increase in mitochondrial proapoptotic combined with a decrease in mitochondrial antiapoptotic proteins of the Bax-Bcl2 family.
The Receptor for Parathyroid Hormone and Parathyroid Hormone-Related Peptide Is Hydrolyzed and Its Signaling Properties Are Altered by Directly Binding the Calpain Small Subunit
Authors: Shimada Masako , Mahon Matthew J. , Greer Peter A. , Segre Gino V.
Published: February 2005

We show calcium-dependent, direct binding between the N-terminal portion of the PTH/PTHrP receptor (PTH1R) C-terminal intracellular tail and the calpain small subunit. Binding requires, but may not be limited to, amino acids W474, S475, and W477. The wild-type, full-length rat (r) PTH1R, but not rPTH1R with W474A/W477A substitutions, copurifies with the endogenous calpain small subunit in HEK293 cells. Calpain hydrolyzes ΔNt-rPTH1R, a receptor with a 156-amino acid N-terminal deletion, in a calcium-dependent manner in vitro and in intact cells. Most importantly, PTH stimulation increases the cleavage of ΔNt-rPTH1R and rPTH1R-yellow fluorescent protein in HEK293 cells, and of talin in HEK293 cells expressing rPTH1R-yellow fluorescent protein and in ROS17/2.8 osteoblast-like cells that express rPTH1R endogenously. The absence of calpain in Capn4-null embryonic fibroblasts and the lowered calpain activity in MC3T3-E1 osteoblastic cells due to stable expression of the calpain inhibitor, calpastatin, reduce PTH-stimulated cAMP accumulation. The calpain small subunit is the second protein, in addition to the sodium-hydrogen exchanger regulatory factor, and the first enzyme that binds the PTH1R; PTH1R bound to both of these proteins results in altered PTH signaling.
Cobalt Chloride-Induced Estrogen Receptor α Down-Regulation Involves Hypoxia-Inducible Factor-1α in MCF-7 Human Breast Cancer Cells
Authors: Cho Jungyoon , Kim Dukkyung , Lee SeungKi , Lee YoungJoo
Published: February 2005

The estrogen receptor (ER) is down-regulated under hypoxia via a proteasome-dependent pathway. We studied the mechanism of ERα degradation under hypoxic mimetic conditions. Cobalt chloride-induced ERα down-regulation was dependent on the expression of newly synthesized protein(s), one possibility of which was hypoxia-inducible factor-1α (HIF-1α). To examine the role of HIF-1α expression in ERα down-regulation under hypoxic-mimetic conditions, we used a constitutively active form of HIF-1α, HIF-1α/herpes simplex viral protein 16 (VP16), constructed by replacing the transactivation domain of HIF-1α with that of VP16. Western blot analysis revealed that HIF-1α/VP16 down-regulated ERα in a dose-dependent manner via a proteasome-dependent pathway. The kinase pathway inhibitors PD98059, U0126, wortmannin, and SB203580 did not affect the down-regulation. A mammalian two-hybrid screen and immunoprecipitation assays indicated that ERα interacted with HIF-1α physically. These results suggest that ERα down-regulation under hypoxia involves protein-protein interactions between the ERα and HIF-1α.
Unmodified Prolactin (PRL) and S179D PRL-Initiated Bioluminescence Resonance Energy Transfer between Homo- and Hetero-Pairs of Long and Short Human PRL Receptors in Living Human Cells
Authors: Tan Dunyong , Johnson David A. , Wu Wei , Zeng Lingfang , Chen Yen Hao , Chen Wen Y. , Vonderhaar Barbara K. , Walker Ameae M.
Published: February 2005

We have used bioluminescence resonance energy transfer (BRET) to examine the interaction between human prolactins (PRLs) and the long (LF) and two short isoforms (SF1a and SF1b) of the human PRL receptor in living cells. cDNA sequences encoding the LF, SF1a, and SF1b were subcloned into codon-humanized vectors containing cDNAs for either Renilla reniformis luciferase (Rluc) or a green fluorescent protein (GFP2) with a 12- or 13-amino acid linker connecting the parts of the fusion proteins. Transfection into human embryonic kidney 293 cells demonstrated maintained function of Rluc and GFP2 when linked to the receptors, and confocal microscopy demonstrated the localization of tagged receptors in the plasma membrane by 48 h after transfection. All three tagged receptors transduced a signal, with the LF and SF1a stimulating, and SF1b inhibiting, promoter activity of an approximately 2.4-kb β-casein-luc construct. Both unmodified PRL (U-PRL) and the molecular mimic of phosphorylated PRL, S179D PRL, induced BRET with all combinations of long and short receptor isoforms except SF1a plus SF1b. No BRET was observed with the site two-inactive mutant, G129R PRL. This is the first demonstration, 1) that species homologous PRL promotes both homo- and hetero-interaction of most long and short PRLR pairs in living cells, 2) that both U-PRL and S179D PRL are active in this regard, and 3) that there is some aspect of SF1a-SF1b structure that prevents this particular hetero-receptor pairing. In addition, we conclude that preferential pairing of different receptor isoforms is not the explanation for the different signaling initiated by U-PRL and S179D PRL.
Three’s Company: Two or More Unrelated Receptors Pair with the Same Ligand
Authors: Ben-Shlomo Izhar , Hsueh Aaron J. W.
Published: February 2005

Intercellular communication relies on signal transduction mediated by extracellular ligands and their receptors. Although the ligand-receptor interaction is usually a two-player event, there are selective examples of one polypeptide ligand interacting with more than one phylogenetically unrelated receptor. Likewise, a few receptors interact with more than one polypeptide ligand, and sometimes with more than one coreceptor, likely through an interlocking of unique protein domains. Phylogenetic analyses suggest that for certain triumvirates, the matching events could have taken place at different evolutionary times. In contrast to a few polypeptide ligands interacting with more than one receptor, we found that many small nonpeptide ligands have been paired with two or more plasma membrane receptors, nuclear receptors, or channels. The observation that many small ligands are paired with more than one receptor type highlights the utilitarian use of a limited number of cellular components during metazoan evolution. These conserved ligands are ubiquitous cell metabolites likely favored by natural selection to establish novel regulatory networks. They likely possess structural features useful for designing agonistic and antagonistic drugs to target diverse receptors.
Traumatic Atlanto-occipital Dislocation: Presentation of a New Posterior Occipitoatlantoaxial Fixation Technique in an Adult Survivor: Technical Case Report
Authors: Payer Michael , Sottas Cyrille C.
Published: February 2005

OBJECTIVE AND IMPORTANCE:

More survivors of traumatic atlanto-occipital dislocation (AOD) in adults have recently been reported. Surgical management options are therefore of increasing interest. We present a new technique of posterior C0–C1–C2 fixation.

CLINICAL PRESENTATION:

A 29-year-old motorcyclist survived a traumatic vertical AOD of 15 mm. No spinal cord or medullary lesion was present. Brain contusion and diffuse axonal injuries led to a cortical biplegia, which recovered progressively over a period of 6 months. Twelve months after surgery, no neurological deficit was present except for slightly increased deep tendon reflexes.

INTERVENTION:

Posterior C0–C1–C2 fixation was performed with two bicortical occipital screws, one bicortical lateral mass screw in the atlas, and one monocortical pars screw in the axis on each side, connected to a plate-rod on the right and left sides. Fusion was performed with monocortical bone graft from the posterior iliac crest.

CONCLUSION:

The surgical technique described was thought to be safe to perform and resulted in immediate stability without external immobilization. Solid fusion was achieved 6 months after surgery.
Frameless Stereotaxy to Facilitate Anterolateral Thoracolumbar Surgery: Technique
Authors: Chappell E Thomas , Pare Laura , Dolich Matthew O. , Lekawa Michael E. , Salepour Mohammed
Published: February 2005

WITH THE ADVENT of frameless stereotaxy and its application to the spine, more precise and less invasive spinal procedures are possible. In addition to being less invasive, these techniques may increase surgeon confidence and allow shorter operating times. Described here is a case of Pott's disease of the thoracolumbar spine and how intraoperative image guidance can facilitate operative progress and accuracy in a patient in whom the underlying disease has severely deformed the normal anatomy of the spine. Added confidence about the location of vital structures as the surgeon proceeds with resection of the vertebral bodies and discs is depicted. Facilitation with image-guided placement of bicortical vertebral body screws and an interbody device is demonstrated. A diagram of the recommended positioning of the equipment in the operating room is provided along with “pearls” learned from our experience with this application. We believe that even the most experienced and skilled surgeon will find facilitation of anterior thoracolumbar surgery with image guidance to be of considerable benefit.
Endoscopic Aqueductal Stenting via the Fourth Ventricle under Navigating System Guidance: Technical Note
Authors: Hamada Hideo , Hayashi Nakamasa , Kurimoto Masanori , Endo Shunro
Published: February 2005

OBJECTIVE:

We report three patients with symptomatic isolated fourth ventricle after ventriculoperitoneal shunt placement for hydrocephalus associated with ventricular hemorrhage. All three patients were treated successfully with our new method of endoscopic aqueductal stenting under navigating system guidance.

METHODS:

A therapeutic rigid endoscope was inserted through the thin cerebellar hemisphere, and endoscopic aqueductal stenting was performed via the enlarged fourth ventricle under navigating system guidance.

RESULTS:

All three patients underwent successful procedures with good outcomes.

CONCLUSION:

Our method of aqueductal stenting is a reasonable choice for initial treatment of patients with isolated fourth ventricle, and it entails less invasive neurosurgery.
Techniques for the Ventral Correction of Postsurgical Cervical Kyphotic Deformity
Authors: Stewart Todd J. , Steinmetz Michael P. , Benzel Edward C.
Published: February 2005

PROGRESSIVE KYPHOTIC DEFORMITY of the cervical spine may be a late sequela of congenital cervical anomalies, degenerative disc disease, neoplasm, cervical trauma, and surgical procedures. Of these, postsurgical kyphosis is the most common and can occur after ventral and dorsal surgeries of the cervical spine. The purpose of this article is to review the causes and clinical presentation of postsurgical cervical kyphosis and to focus on the operative planning and ventral correction techniques.
Anatomic and Surgical Basis of the Sphenoid Ridge Keyhole Approach for Cerebral Aneurysms
Authors: Nathal Edgar , Gomez-Amador Juan Luis
Published: February 2005

IN VASCULAR NEUROSURGERY, the pterional approach has been used primarily for the treatment of a wide variety of diseases (cavernous angiomas, arteriovenous malformations, etc.), and it is used to take advantage of naturally occurring planes and spaces to expose the major structures of the circle of Willis. It provides access to the major part of the anterior circulation aneurysms and those occurring in the upper and most proximal part of the posterior circulation. Conversely, there has been an increasing interest in the so-called minimally invasive procedures or keyhole approaches to treating cerebral aneurysms in specific locations. In this work, we describe a novel keyhole approach that was conceived to achieve the angle of vision and advantages of the classic pterional approach. This surgical approach is based on the anatomic location of the sphenoid ridge and its relationship with the sylvian fissure and basal cisterns. The initial incision is made over the hairline behind the external border of the eye on the side selected. A skin and muscular flap is reflected anteriorly, and a small 3 × 3-cm craniotomy is completed around the external landmarks of the sphenoid ridge. Further extradural drilling is completed down to the anterior clinoid process. The dura is opened in a semilunar manner, and the sylvian fissure is opened completely to reach the sylvian and basal cisterns. Thereafter, the aneurysm is dissected and clipped according to the standard microtechnique of the neurosurgeon. A step-by-step description of the approach is offered in this work to facilitate a clear understanding of it. We recommend this approach for treatment of aneurysms arising at the anterior part of the circle of Willis. It has the advantages of less operative time, fewer days of hospitalization, and similar morbidity and mortality compared with the standard pterional craniotomy (5.7% on our service for nongiant ruptured aneurysms).
Cortical Surface Tracking Using a Stereoscopic Operating Microscope
Authors: Sun Hai , Roberts David W. , Farid Hany , Wu Ziji , Hartov Alex , Paulsen Keith D.
Published: February 2005

OBJECTIVE:

To measure and compensate for soft tissue deformation during image-guided neurosurgery, we have developed a novel approach to estimate the three-dimensional (3-D) topology of the cortical surface and track its motion over time.

METHODS:

We use stereopsis to estimate the 3-D cortical topology during neurosurgical procedures. To facilitate this process, two charge-coupled device cameras have been attached to the binocular optics of a stereoscopic operating microscope. Before surgery, this stereo imaging system is calibrated to obtain the extrinsic and intrinsic camera parameters. During surgery, the 3-D shape of the cortical surface is automatically estimated from a stereo pair of images and registered to the preoperative image volume to provide navigational guidance. This estimation requires robust matching of features between the images, which, when combined with the camera calibration, yields the desired 3-D coordinates. After the 3-D cortical surface has been estimated from stereo pairs, its motion is tracked by comparing the current surface with its previous locations.

RESULTS:

We are able to estimate the 3-D topology of the cortical surface with an average error of less than 1.2 mm. Executing on a 1.1-GHz Pentium machine, the 3-D estimation from a stereo pair of 1024 × 768 resolution images requires approximately 60 seconds of computation. By applying stereopsis over time, we are able to track the motion of the cortical surface, including the pulsatile movement of the cortical surface, gravitational sag, tissue bulge as a result of increased intracranial pressure, and the parenchymal shape changes associated with tissue resection. The results from 10 surgical patients are reported.

CONCLUSION:

We have demonstrated that a stereo vision system coupled to the operating microscope can be used to efficiently estimate the dynamic topology of the cortical surface during surgery. The 3-D surface can be coregistered to the preoperative image volume. This unique intraoperative imaging technique expands the capability of the current navigational system in the operating room and increases the accuracy of anatomic correspondence with preoperative images through compensation for brain deformation.
Surgical Technique of Lumbar Artificial Disc Replacement with the Charité Artificial Disc
Authors: Geisler Fred H.
Published: February 2005

LUMBAR ARTIFICIAL DISC technology has been commercially available outside the United States for nearly 2 decades. With the Food and Drug Administration approval of the Charité Artificial Disc in October 2004, an entirely new spinal surgeon population will be able to offer this technology to their patients as a treatment option. As with other techniques in spinal surgery, indications for lumbar total disc replacement are paramount to the success of the procedure. The correct surgical technique is also important to a successful outcome. This article describes the technique for placement of the Charité Artificial Disc in indicated patients. The technique is similar to that of an anterior lumbar interbody fusion procedure, but many differences between the techniques make lumbar total disc replacement a unique procedure in the spinal surgeon's armamentarium. Although this article is thorough in its description of the surgical technique for total disc replacement with the Charité Artificial Disc, it should not be used as a substitute for company-sponsored training.
Cervical Arthroplasty with the Bryan Disc
Authors: Wang Michael Y. , Leung Clarence H.S. , Casey Adrian T.H.
Published: February 2005

CERVICAL ARTHROPLASTY IS a promising nonfusion alternative for the treatment of degenerative disc disease. After anterior cervical discectomy for neurological decompression, the intervertebral space is reconstructed by use of a metal and polymer prosthesis, allowing semiconstrained motion in multiple planes. This approach allows for preservation of cervical motion, potentially reducing the risk of transitional-level disease.
Her odours make him deaf: crossmodal modulation of olfaction and hearing in a male moth
Authors: Skals Niels , Anderson Peter , Kanneworff Morten , Löfstedt Christer , Surlykke Annemarie
Published: February 2005

All animals have to cope with sensory conflicts arising from simultaneous input of incongruent data to different sensory modalities. Nocturnal activity in moths includes mate-finding behaviour by odour detection and bat predator avoidance by acoustic detection. We studied male moths that were simultaneously exposed to female sex pheromones indicating the presence of a potential mate, and artificial bat cries simulating a predation risk. We show that stimulation of one sensory modality can modulate the response to information from another, suggesting that behavioural thresholds are dynamic and depend on the behavioural context. The tendency to respond to bat sounds decreased as the quality and/or the amount of sex pheromone increased. The behavioural threshold for artificial bat cries increased by up to 40 dB when male moths where simultaneously exposed to female sex pheromones. As a consequence, a male moth that has detected the pheromone plume from a female will not try to evade an approaching bat until the bat gets close, hence incurring increased predation risk. Our results suggest that male moths'reaction to sensory conflicts is a trade-off depending on the relative intensity of the input to CNS from the two sensory modalities.
Odor-modulated orientation in walking male cockroachesPeriplaneta americana, and the effects of odor plumes of different structure
Authors: Willis M. A. , Avondet J. L.
Published: February 2005

The location of distant resources using odor information usually also requires information on the flow of air (or water) through the environment together with the expression of internally programmed steering responses. The orientation responses of virgin male Periplaneta americana L. to wind and the female sex-pheromone component (-)-periplanone-B were video-recorded in a laboratory wind tunnel and quantified. P. americana males showed no preferred walking orientation when released in zero wind in the absence of pheromone. When introduced into 25 cm s-1 wind in the absence of pheromone, 79% of males walked downwind. Upon introduction to a plume of(-)-periplanone-B in wind, 100% of males walked upwind in the pheromone plume to the source. Males were then challenged with wind-borne plumes of(-)-periplanone-B of four different temporal/spatial structures. In nearly all cases, the only statistically significant changes in behavioral parameters measured from their walking tracks were observed from males tracking the treatment consisting of the most turbulent plume. The plume-tracking performances of males challenged with the other three less turbulent plumes were visually and quantitatively similar, regardless of the width. Males tracking all four plumes showed evidence of turns resulting from multiple mechanisms. Some of the observed maneuvers were temporally regular counterturns, suggesting steering according to an ongoing internal program,while others could have been triggered by encountering the change in odor concentration between pheromone and clean air at the lateral boundary of the plume or chemotactically upon the detection of changes in odor concentration.
Sites and modes of action of proctolin and the FLP F2 on lobster cardiac muscle
Authors: Wilkens J. L. , Shinozaki T. , Yazawa T. , ter Keurs H. E. D. J.
Published: February 2005

At the threshold concentration (1-10 pmol l-1), the neuropeptide hormones proctolin (PR) and the FLRFamide-like peptide (FLP) F2cause an increase in amplitude of electrically evoked contractions (each contraction is a brief tetanus) of lobster heart ostial muscle. At higher concentrations each peptide also induces an increase in tonus (contracture). The PR-induced contracture and augmentation of tetani are proportional to increases in [Ca2+]i. The rate of onset and recovery of peptide-induced effects on both tetani and contracture appeared to reduced by Ca2+ storage by the sarcoplasmic reticulum (SR). Enhanced tetani following a contracture may be due to enhanced voltage-gated Ca2+current and sarcoplasmic reticular (SR) Ca2+ loading. The SR Ca2+ loading appears to be specific for PR and F2, since glutamic-acid-induced contractures are not followed by increased tetani. The prolonged elevation of [Ca2+]i during contracture causes a right-ward shift in the force-pCa curve indicating a decrease in myofibrillar sensitivity to Ca2+. Blocking voltage-gated Ca2+ channels with Cd2+, nifedipine or verapamil, while reducing tetani, does not prevent peptide-induced contracture and enhanced tetani. Opening SR Ca2+ channels and depleting SR Ca2+with either caffeine or ryanodine blocked tetani but permitted accelerated peptide-induced contractures. We conclude that PR and F2 at low concentration enhance voltage-dependent Ca2+ induced Ca2+ release from the SR, while higher hormone levels directly gate Ca2+ entry across the sarcolemma.
Walking on inclines: energetics of locomotion in the antCamponotus
Authors: Lipp Alexandra , Wolf Harald , Lehmann Fritz-Olaf
Published: February 2005

To assess energetic costs during rest and locomotion in a small insect, we measured metabolic rate in freely moving ants Camponotus sp.(average body mass 11.9 mg). The animals ran in a straight respirometric chamber in which locomotor speed and CO2 release were monitored simultaneously using flow-through respirometry and conventional video analysis. In resting intact ants, standard metabolic rate was on average 0.32 ml CO2 g-1 body mass h-1. During walking, the ants breathed continuously and metabolic rate increased between 4.3 times(level walking at 0-5 mm s-1) and 6.9 times (30° ascent at 85-95 mm s-1) over resting rates. Metabolic rate increased linearly with increasing walking speed but superficially leveled off beyond speeds of about 70 mm s-1. Walking on incline (uphill) or decline slopes(downhill) of up to 60° had only a small effect on energy consumption compared to level walking. During slope walking, total metabolic rate averaged over all running speeds ranged from a minimum of 1.55±0.4 (horizontal running) to a maximum of 1.89±0.7 ml CO2 h-1g-1 body mass (30° downhill). The mean cost of transport in Camponotus was approximately 130 J g-1 km-1. The metabolic requirements in the comparatively small insect Camponotus for walking were mostly in the range expected from data obtained from other insects and small poikilotherms, and from allometric scaling laws.
Intracellular calcium and survival of tadpole forebrain cells in anoxia
Authors: Hedrick Michael S. , Fahlman Christian S. , Bickler Philip E.
Published: February 2005

The frog brain survives hypoxia with a slow loss of energy charge and ion homeostasis. Because hypoxic death in most neurons is associated with increases in intracellular calcium ([Ca2+]i), we examined the relationship between [Ca2+]i and survival of a mixed population of isolated cells from the forebrain of North American bullfrog Rana catesbeiana tadpoles. Forebrain cells from stage V-XV tadpoles were isolated by enzymatic digestion and loaded with one of three different calcium indicators (Fura-2, Fura 2-FF and BTC) to provide estimates of [Ca2+]i accurate at low and high[Ca2+]i. Propidium iodide (PI) fluorescence was used as an indicator of cell viability. Cells were exposed to anoxia (100%N2) and measurements of [Ca2+]i and cell survival made from 1 h to 18 h. Intracellular [Ca2+] increased significantly after 3-6 h anoxia (P<0.05), regardless of the type of Ca2+ indicator used; however, there were substantial differences in the measurements of [Ca2+]i with the different indicators, reflecting their varying affinities for Ca2+. Resting[Ca2+]i was approximately 50 nmol l-1 and increased to about 9-30 μmol l-1 after 4-6 h anoxia. The significant increase in [Ca2+]i during anoxia was not associated with significant increases in cell death, with 85-95% survival over this time period. Cells exposed to anoxia for 18 h, or those made anoxic for 4-6 and reoxygenated for 12 h to 16 h, had survival rates greater than 70%,but survival was significantly less than normoxic controls. These results indicate that large increases in [Ca2+]i are not necessarily associated with hypoxic cell death in vertebrate brain cells.
Lifespan extension and elevatedhspgene expression inDrosophilacaused by histone deacetylase inhibitors
Authors: Zhao Yanmei , Sun Hui , Lu Jun , Li Xiaoxue , Chen Xia , Tao Dan , Huang Weifeng , Huang Baiqu
Published: February 2005

The heat shock proteins (Hsps) play a positive role in lifespan determination, and histone acetylation has been shown to be involved in transcription of hsp genes in Drosophila. To further determine if hsp22 and hsp70 expression is correlated with lifespan, and if histone acetylation participates in this process, RNA levels for hsp22 and hsp70 were analyzed throughout the lifespan in the long-lived and short-lived iso-female lines. The results showed that hsp22 and hsp70 RNA levels were higher in long-lived line than in short-lived line and that the long-lived flies responded more rapidly to heat but were more tolerant to high temperature. Moreover, we investigated the influences of histone acetylation modification on longevity and on hsp gene expression by using histone deacetylase (HDAC) inhibitors TSA and BuA. The results demonstrated that both inhibitors were able to extend the lifespan and promote hsp22 and hsp70 expression. However, the optimal concentrations of these inhibitors, and probably the mechanisms of their actions, vary with the genetic background. In addition, we showed that HDAC inhibitors caused the hyperacetylation of core histone H3,implicating the involvement of chromatin modulation in hsp gene transcription. These data suggested a close correlation among histone acetylation, hsp gene expression and longevity in D. melanogaster.
Increased Oxidative DNA Damage, as Assessed by Urinary 8-Hydroxy-2′-Deoxyguanosine Concentrations, and Serum Redox Status in Persons Exposed to Mercury
Authors: Chen Chunying , Qu Liya , Li Bai , Xing Li , Jia Guang , Wang Tiancheng , Gao Yuxi , Zhang Peiqun , Li Mei , Chen Wei , Chai Zhifang
Published: February 2005

Background: Mercury is a ubiquitous and highly toxic environmental pollutant. In this study, we evaluated the relationship between mercury exposure and oxidative stress, serum and urinary mercury concentrations, oxidative DNA damage, and serum redox status in chronically mercury-exposed persons compared with healthy controls.

Methods: We measured urinary 8-hydroxy-2′-deoxyguanosine (8-OHdG), which we used as a biomarker of oxidative DNA damage in the mercury-exposed persons, by HPLC with electrochemical detection (ECD). We evaluated antioxidant status by measuring the activities of superoxide dismutase and glutathione peroxidase and the concentrations of total reduced glutathione and protein-bound thiols in serum.

Results: The significant increase in 8-OHdG concentrations in urine indicated that mercury-induced oxidative damage to DNA occurred in vivo. Differences in body mercury burden and antioxidant enzyme activities were statistically significant between the mercury-exposed persons and controls. Serum and urinary mercury concentrations in the mercury-exposed persons were more than 40-fold higher than in controls.

Conclusions: Mercury exposure can induce oxidative DNA damage, whereas the antioxidative repair systems can be expected to minimize DNA lesions caused by mercury. Measurement of urinary 8-OHdG could be useful for evaluating in vivo oxidative DNA damage in mercury-exposed populations.
Dual concentration-dependent activity of thyroglobulin type-1 domain of testican: specific inhibitor and substrate of cathepsin L
Authors: Meh Primož , Pavšič Miha , Turk Vito , Baici Antonio , Lenarčič Brigita
Published: February 2005

The thyroglobulin type-1 (Tg-1) domain is a protein module that occurs in a variety of secreted and membrane proteins and is recognised as a potent inhibitor of cysteine peptidases. We present here some properties of the Tg-1 domain of human testican, a modularly organised proteoglycan secreted mainly by brain cells, the exactin vivofunction of which is not yet clear. The domain was prepared as a recombinant protein in aPichia pastorisexpression system and its activity was demonstrated by specific and selective inhibition of cathepsin L (Ki=0.14 nM). Interaction at high enzyme and inhibitor concentrations resulted in degradation of the domain by cathepsin L, which was not observed under conditions used for the determination of kinetic parameters. No inhibitory activity could be detected for cathepsin K, but it exhibited a very similar degradation pattern. Homology modelling provided a good explanation for the different behaviour observed with the two enzymes. Firstly, the steric fit between the interfaces of testican domain and cathepsin L is stabilised by numerous favourable forces, while no such interactions are evident in the complex with cathepsin K, and repulsive interactions even prevent access of the domain to the active site of papain. Secondly, the prolonged first loop of the domain occupies a position near the catalytic cysteine residue in a more substrate-like manner, enabling cleavage of the Gly22-Ala23bond.
50 Jahre Entdeckung des piezoresistiven Effekts – Geschichte und Entwicklungsstand piezoresistiver Sensoren (50 Years of Piezoresistive Sensors – History and State of the Art of Piezoresistive Sensors)
Authors: Gerlach Gerald , Werthschützky Roland
Published: February 2005

Am 1. April 1954 erschien in der Zeitschrift Physical Review ein Aufsatz von Charles S. Smith , in dem erstmalig über den piezoresistiven Effekt berichtet wurde, den er bei den kubischen Halbleitern Germanium und Silizium beobachtet hatte [1]. Mit dieser Entdeckung begann die Entwicklung diskreter Silizium-Dehnmessstreifen, die gegenüber Metall-DMS einen bis zu einem Faktor von 20...50 größeren K-Faktor aufweisen. Mit der Integration diffundierter Widerstände direkt in das Silizium und der Schaffung lokal abgedünnter Bereiche im Silizium, die dann als drucksensitiver Verformungskörper wirkten, wurden neben den piezoresistiven Wandlereigenschaften nun auch die ausgezeichneten mechanischen Eigenschaften von Silizium ausgenutzt. Rund zwei Jahrzehnte haben dann piezoresistive Sensoren die Entwicklung der Mikrosystemtechnik mit ihren vielfältigen Fertigungsverfahren mitbestimmt und damit vielen anderen mikroelektromechanischen Systemen (MEMS) den Weg bereitet [2;3;4] (Tabelle 1). Auch nach 50 Jahren der Entwicklung piezoresistiver Aufnehmer stellt diese Sensorklasse noch ein wissenschaftlich interessantes Gebiet dar.
Messunsicherheit piezoresistiver Sensoren (Uncertainty in the Measurement of Piezoresistive Sensors)
Authors: Hoa Phan L. P. , Suchaneck Gunnar , Gerlach Gerald
Published: February 2005

Dieser Beitrag betrachtet die Messunsicherheit piezoresistiver Drucksensoren entsprechend dem von der ISO herausgegebenen Guide to the „Expression of Uncertainty in Measurement“, kurz GUM genannt. Es wird gezeigt, dass das Rauschen im Sensor stark durch die Sensorpassivierung beeinflusst wird. Neben der Temperatur erwies sich die Feuchtigkeit als zweite bedeutsame Ursache der Messunsicherheit.
Role of gap junctions during early embryo development
Authors: Houghton Franchesca D
Published: February 2005

Gap junctional communication plays a central role in the maintenance of cellular homeostasis by allowing the passage of small molecules between adjacent cells. Gap junctions are composed of a family of proteins termed connexins. During preimplantation development several connexin proteins are expressed and assembled into gap junctions in the plasma membrane at compaction but the functional significance of connexin diversity remains controversial. Although, many of the connexin genes have been disrupted using homologous recombination in embryonic stem cells to obtain unique phenotypes, none of these studies has demonstrated a specific role for connexins during preimplantation development in the null mutants. This review surveys evidence for the involvement of gap junctional communication during embryo development highlighting discrepancies in the literature. Although some evidence suggests that gap junctions may be dispensable during preimplantation development this is difficult to envisage particularly for the process of cavitation and the maintenance of homeostasis between the differentiated trophectoderm cells and the pluripotent inner cell mass cells of the blastocyst.
Translocation of phospho-protein kinase Cs implies their roles in meiotic-spindle organization, polar-body emission and nuclear activity in mouse eggs
Authors: Zheng Zhen-Yu , Li Qing-Zhang , Chen Da-Yuan , Schatten Heide , Sun Qing-Yuan
Published: February 2005

The protein kinase Cs (PKCs) are a family of Ser/Thr protein kinases categorized into three subfamilies: classical, novel, and atypical. The phosphorylation of PKC in germ cells is not well defined. In this study, we described the subcellular localization of phopho-PKC in the process of mouse oocyte maturation, fertilization, and early embryonic mitosis. Confocal microscopy revealed that phospho-PKC (pan) was distributed abundantly in the nucleus at the germinal vesicle stage. After germinal vesicle breakdown, phospho-PKC was localized in the vicinity of the condensed chromosomes, distributed in the whole meiotic spindle, and concentrated at the spindle poles. After metaphase I, phospho-PKC was translocated gradually to the spindle mid-zone during emission of the first polar body. After sperm penetration and electrical activation, the distribution of phospho-PKC was moved from the spindle poles to the spindle mid-zone. After the extrusion of the second polar body (PB2) phospho-PKC was localized in the area between the oocyte and the PB2. In fertilized eggs, phospho-PKC was concentrated in the pronuclei except for the nucleolus. Phospho-PKC was dispersed after pronuclear envelope breakdown, but distributed on the entire spindle at mitotic metaphase. The results suggest that PKC activation may play important roles in regulating spindle organization and stabilization, polar-body extrusion, and nuclear activity during mouse oocyte meiosis, fertilization, and early embryonic mitosis.
Cats cloned from fetal and adult somatic cells by nuclear transfer
Authors: Yin X J , Lee H S , Lee Y H , Seo Y I , Jeon S J , Choi E G , Cho S J , Cho S G , Min W , Kang S K , Hwang W S , Kong I K
Published: February 2005

This work was undertaken in order to study the developmental competence of nuclear transfer (NT ) into cat embryos using fetal fibroblast and adult skin fibroblast cells as donor nuclei. Oocytes were recovered by mincing the ovaries in Hepes-buffered TCM199 and selecting the cumulus oocyte complexes (COCs) with compact cumulus cell mass and dark color. Homogenous ooplasm was cultured for maturation in TCM199+10% fetal bovine serum (FBS) for 12 h and used as a source of recipient cytoplast for exogenous somatic nuclei. In experiment 1, we evaluated the effect of donor cell type on the reconstruction and development of cloned embryos. Fusion, first cleavage and blastocyst developmental rate were not different between fetal fibroblasts and adult skin cells (71.2 vs 66.8; 71.0 vs 57.6; 4.0 vs 6.1% respectively; P < 0.05). In experiment 2, cloned embryos were surgically transferred into the oviducts of recipient queens. One of the seven recipient queens was delivered naturally of 2 healthy cloned cats and 1 stillborn from fetal fibroblast cells of male origin 65 days after embryo transfer. One of three recipient queens was delivered naturally of 1 healthy cloned cat from adult skin cells of female origin 65 days after embryo transfer. The cloned cats showed genotypes identical to the donor cell lines, indicating that adult somatic cells can be used for feline cloning.
Contribution of high p34cdc2 kinase activity to premature chromosome condensation of injected somatic cell nuclei in rat oocytes
Authors: Ito Junya , Hirabayashi Masumi , Kato Megumi , Takeuchi Ayumu , Ito Mayumi , Shimada Masayuki , Hochi Shinichi
Published: February 2005

The present study was undertaken to clarify the relationship between the p34cdc2kinase activity ofin vitro-aged or enucleated rat oocytes and the premature chromosome condensation (PCC) of microinjected cumulus cell nuclei. Wistar rat oocytes were placedin vitroup to 120 min after the animal was killed. The p34cdc2kinase activity of the oocytes decreased in a time-dependent manner. The incidence of PCC was higher when nuclear injection into intact oocytes was completed in 15–45 min rather than 46–120 min. When rat oocytes were enucleated for subsequent nuclear injection, the p34cdc2kinase activity transiently increased soon after enucleation but drastically decreased after 30 min. Removal of the cytoplasm instead of the meta-phase-plate did not affect the p34cdc2kinase activity even after 60 min. PCC occurred in intact and cytoplasm-removed oocytes but not in enucleated oocytes. In contrast, oocytes from BDF1 mice exhibited a p34cdc2kinase level twice that of rat oocytes and supported PCC despite enucleation. The p34cdc2kinase level of intact rat oocytes was reduced to the equivalent level of aged (120 min) or enucleated (+60 min) oocytes by a 45 min treatment with roscovitine, an inhibitor of p34cdc2kinase. None of the roscovitine-treated oocytes supported PCC while half of the control oocytes did. When rat oocytes were treated with MG132, a proteasome inhibitor, delayed inactivation of the p34cdc2kinase was observed in the MG132-treated oocytes. A significantly higher proportion of the MG132-treated oocytes supported PCC when compared with the control oocytes. Moreover, a higher proportion of MG132-treated and enucleated oocytes carried two pseudo-pronuclei after cumulus cell injection and developed to the two-cell stage when compared with the enucleated oocytes at the telophase-II stage. These results suggest that the decreased level of p34cdc2kinase activity in aged or enucleated rat oocytes is responsible for their inability to support PCC of microinjected donor cell nuclei and that inhibition of p34cdc2kinase inactivation by chemicals such as MG132 is in part effective for rat oocytes to promote PCC and further development.
Photoperiod-induced differential expression of angiogenesis genes in testes of adult Peromyscus leucopus
Authors: Pyter Leah M , Hotchkiss Andrew K , Nelson Randy J
Published: February 2005

Non-pathological angiogenesis in adults is rare and is largely thought to be restricted to wound healing and female reproductive cycles. Adult male rodents, however, display seasonal angiogenesis to support seasonal changes in reproductive tissue morphology. Non-tropical rodents use photoperiod (day length) to determine the time of year. During short days, the reproductive system undergoes involution and mating behaviours stop, adaptations which presumably allow energy resources to be shifted to processes necessary for winter survival. We compared the patterns of gene expression involved in angiogenesis in testes of white-footed mice (Peromyscus leucopus) following 7, 14, 21 or 34 weeks of long or short day lengths. Short days decreased body mass, reproductive tract mass and seminiferous tubule diameter. Potential genes involved in seasonal angiogenesis were screened by hybridizing testicular RNA from each group to angiogenesis-specific microarrays. Genes that were ≥6-fold different between long- and short-day testes (i.e. hypoxia-inducible factor 1α(Hif1α), plasminogen activator inhibitor 1 (Serpine1), transforming growth factor β receptor 3 (Tgfβr3) and tumour necrosis factor (Tnf)) were sequenced and expression differences were compared throughout gonadal regression and recrudescence using quantitative RT-PCR. Our results suggest that short days trigger expression ofHif1α,Serpine1, andTgfβr3to inhibit angiogenesis or promote apoptosis during testicular regression, and also trigger expression ofTnfto promote angiogenesis during testicular recrudescence.
Mechanisms of action of angiotensin II on mammalian sperm function
Authors: Mededovic Samra , Fraser Lynn R
Published: February 2005

Angiotensin II (AII) stimulates capacitation and fertilizing ability in mammalian spermatozoa, with the binding of AII to its receptors resulting in stimulation of cAMP production in both uncapacitated and capacitated cells. This study investigated possible mechanisms whereby AII affects cAMP availability. The first question was whether extracellular Ca2+is required for responses in mouse spermatozoa and, using chlortetracycline fluorescence analysis, it was clear that cells responded to AII only when the medium contained CaCl2, with both 90 μM and 1.80 mM supporting a significant acceleration of capacitation. Consistent with those results, AII significantly stimulated cAMP production in both CaCl2-containing media tested, the response being greater in that containing 1.80 mM. Several different agents that might affect the signalling pathway stimulated by AII were then evaluated in uncapacitated suspensions. Chlortetracycline analysis revealed that pertussis toxin abolished responses to AII, suggesting the involvement of an inhibitory Gα subunit; dideoxyadenosine, a specific membrane-associated adenylyl cyclase (mAC) P-site inhibitor, also blocked responses, suggesting involvement of an mAC. cAMP determinations con-firmed that both reagents also abolished AII’s stimulation of cAMP. In contrast, nifedipine, a Ca2+channel blocker, did not inhibit AII’s effects on spermatozoa. Finally, in capacitated suspensions, both pertussis toxin and dideoxyadenosine were again shown to block AII’s stimulation of cAMP. These results suggest that responses to AII involve an inhibitory G protein and an mAC, but it is likely that AII–receptor coupling does not stimulate directly mAC but rather does so in an indirect manner, perhaps by altering the intracellular Ca2+concentration.