bluuebunny/crossref_metadata_2025 huggingface dataset:
Rga5p is a specific Rho1p GTPase‐activating protein that regulates cell integrity in Schizosaccharomyces pombe
Authors: Calonge Teresa M. , Arellano Manuel , Coll Pedro M. , Perez Pilar
Published: March 2003

Schizosaccharomyces pombe
Rho1p regulates (1,3)β‐
d
‐glucan synthesis and is required for cell integrity maintenance and actin cytoskeleton organization, but nothing is known about the regulation of this protein. At least nine different
S. pombe
genes code for proteins predicted to act as Rho GTPase‐activating proteins (GAPs). The results shown in this paper demonstrate that the protein encoded by the gene named
rga5
+
is a GAP specific for Rho1p.
rga5
+
overexpression is lethal and causes morphological alterations similar to those reported for Rho1p inactivation.
rga5
+
deletion is not lethal and causes a mild general increase in cell wall biosynthesis and morphological alterations when cells are grown at 37°C. Upon mild overexpression, Rga5p localizes to growth areas and possesses both
in vivo
and
in vitro
GAP activity specific for Rho1p. Overexpression of
rho1
+
in
rga5Δ
cells is lethal, with a morphological phenotype resembling that of the overexpression of the constitutively active allele
rho1G15V.
In addition (1,3)β‐
d
‐glucan synthase activity, regulated by Rho1p, is increased in
rga5Δ
cells and decreased in
rga5
‐overexpressing cells. Moreover, the increase in (1,3)β‐
d
‐glucan synthase activity caused by
rho1
+
overexpression is considerably higher in
rga5Δ than in wild‐type cells. Genetic interactions suggest that Rga5p is also important for the regulation of the other known Rho1p effectors, Pck1p and Pck2p.
The crk1 gene encodes an Ime2‐related protein that is required for morphogenesis in the plant pathogen Ustilago maydis
Authors: Garrido Elia , Pérez‐Martín José
Published: March 2003

The fungal pathogen Ustilago maydis alternates between budding and filamentous growth during its life cycle. This dimorphic transition is regulated by environmental factors and mating. We cloned a new gene, crk1, which encodes a protein with sequence similarity to Ime2, a kinase involved in developmental choices in S. cerevisiae. Disruption of the crk1 gene in U. maydis resulted in cells that are unable to respond in an appropriate manner to environmental stimuli and show defects in morphogenesis and cell cycle adjustment to changing conditions. We have analysed the regulation of the crk1 gene and demonstrated that cAMP and MAPK pathways have opposite influences on the transcript levels for crk1. Furthermore, we have shown that alterations in the components of these pathways impair the ability of the cellular machinery to adapt to changing conditions. These results demonstrate an important role for the crk1‐ encoded protein in the morphogenesis and environmental adaptation in Ustilago maydis.
Domestication of wild Saccharomyces cerevisiae is accompanied by changes in gene expression and colony morphology
Authors: Kuthan Martin , Devaux Frédéric , Janderová Blanka , Slaninová Iva , Jacq Claude , Palková Zdena
Published: March 2003

Although colonies from Saccharomyces cerevisiae laboratory strains are smooth, those isolated from nature exhibit a structured fluffy pattern. Environmental scanning electron microscopy shows that the cells within wild fluffy colonies are connected by extracellular matrix (ECM) material. This material contains a protein of about 200 kDa unrelated to the flocculins, proteins involved in cell–cell adhesion in liquid media. The matrix material binds to concanavalin A. Within a few passages on rich agar medium, the wild strains switch from the fluffy to the smooth colony morphology. This domestication is accompanied by loss of the ECM and by extensive changes in gene expression as detected by DNA microarrays. The expression of about 320 genes was changed in smooth colonies. The major changes comprise carbohydrate metabolism, cell wall, water channels, Ty‐transposons and subtelomeric genes, iron homeostasis, vitamin metabolism and cell cycle and polarity. The growth in fluffy colonies may represent a metabolic strategy for survival of yeast under unfavourable conditions that is switched off under felicitous laboratory conditions.
Streptococcus pyogenes recruits collagen via surface‐bound fibronectin: a novel colonization and immune evasion mechanism
Authors: Dinkla Katrin , Rohde Manfred , Jansen Wouter T. M. , Carapetis Jonathan R. , Chhatwal Gursharan S. , Talay Susanne R.
Published: March 2003

This study aimed to characterize matrix assembly mechanisms on the surface of the human pathogen Streptococcus pyogenes. Among 125 S. pyogenes isolates, 61% were able to recruit collagen type IV via surface‐bound fibronectin. Streptococcus gordonii expressing the fibronectin‐binding repeat domain of S. pyogenes SfbI protein was equally potent in recruiting collagen, indicating that this domain was sufficient to promote fibronectin‐mediated collagen recruitment. Electron microscopic analysis of streptococci revealed that fibronectin‐mediated collagen recruitment led to matrix deposition on and between streptococcal cells, which induced the formation of large bacterial aggregates. Furthermore, collagen‐recruiting streptococci were able to colonize collagen fibres and were protected from adhering to human polymorphonuclear cells in the presence of op‐sonizing antibodies. Fibronectin‐mediated collagen recruitment thus represents a novel aggregation, colonization and immune evasion mechanism of S. pyogenes.
Activation mechanisms of the HACI‐mediated unfolded protein response in filamentous fungi
Authors: Saloheimo Markku , Valkonen Mari , Penttilä Merja
Published: March 2003

The unfolded protein response (UPR) is a regulatory pathway activating genes involved in multiple functions related to folding, quality control and transport of secreted proteins. Characterization of the hac1/hacA genes encoding the UPR transcription factors from the filamentous fungi Trichoderma reesei and Aspergillus nidulans is described in this article. The corresponding gene in Saccharomyces cerevisiae is activated through a non‐spliceosomal intron‐splicing reaction. The T. reesei hac1 and A. nidulans hacA mRNAs undergo an analogous splicing reaction of a 20‐nt‐long intron during UPR induction. This splicing changes the reading frame of the mRNA and thus could bring in an activation domain to the HACI/HACA proteins. In addition to the non‐spliceosomal splicing, the hac1/A mRNAs of the filamentous fungi are truncated at the 5′‐flanking region upon UPR induction. An upstream open reading frame is omitted from the mRNAs due to the truncation, and evidence is presented showing that the truncated T. reesei hac1 mRNA is translated more efficiently than a full‐length mRNA. This paper reports a novel combination of two different regulatory mechanisms of a transcription factor gene, both operational at the mRNA level.
Conjugal immunity of Streptomyces strains carrying the integrative element pSAM2 is due to the pif gene (pSAM2 immunity factor)
Authors: Possoz Christophe , Gagnat Josette , Sezonov Guennadi , Guérineau Michel , Pernodet Jean‐luc
Published: March 2003

Mechanisms of conjugal immunity preventing redundant exchange between two cells harbouring the same conjugative element have been reported in diverse bacteria. Such a system does exist for pSAM2, a conjugative and integrative element of Streptomyces. The apparition of the conjugative free form of pSAM2 in the donor strain during mating can be considered as the initial step of transfer. We analysed the genes involved in transfer inhibition by mating donors harbouring pSAM2 with recipient strains containing different regions of pSAM2. The conjugal immunity was previously thought to be mediated by the transcriptional repressor KorSA. Although the transfer efficiency is reduced by its presence in the recipient, the initiation of the transfer process is not affected. In contrast, the presence in the recipient strain of a single pSAM2 gene, pif (pSAM2 immunity factor), was sufficient to abolish both transfer and initiation of transfer. Thus, the clustered genes korSA and pif act complementarily to maintain pSAM2 in a ‘prophage’ state under non‐conjugal conditions. KorSA is involved in intracellular signalling, whereas Pif participates in intercellular signalling. The Pif nudix motif is essential for its activity. This is the first protein of the nudix family shown to be involved in bacterial conjugation.
Adaptation of the Lyme disease spirochaete to the mammalian host environment results in enhanced glycosaminoglycan and host cell binding
Authors: Parveen Nikhat , Caimano Melissa , Radolf Justin D. , Leong John M.
Published: March 2003

The Lyme disease spirochaete, Borrelia burgdorferi, is transmitted to mammals by Ixodes ticks and can infect multiple tissues. Host cell attachment may be critical for tissue colonization, and B. burgdorferi cultivated in vitro recognizes heparin‐ and dermatan sulphate‐related glycosaminoglycans (GAGs) on the surface of mammalian cells. To determine whether growth of the spirochaete in the mammalian host alters GAG binding, we assessed the cell attachment activities of B. burgdorferi grown in vitro or in dialysis membrane chambers implanted intraperitoneally in rats. Host‐adapted B. burgdorferi exhibited approximately threefold better binding to purified heparin and dermatan sulphate and to GAGs expressed on the surface of cultured endothelial cells. Three B. burgdorferi surface proteins, Bgp, DbpA and DbpB, have been demonstrated previously to bind to GAGs or to GAG‐containing molecules, and we show here that recombinant derivatives of each of these proteins were able to bind to purified heparin and dermatan sulphate. Immunofluorescent staining of in vitro‐cultivated or host‐adapted spirochaetes revealed that DbpA and DbpB were present on the bacterial surface at higher levels after host adaptation. Recombinant Bgp, DbpA and DbpB each partially inhibited attachment of host‐adapted B. burgdorferi to cultured mammalian cells, consistent with the hypothesis that these proteins may promote attachment of B. burgdorferi during growth in the mammalian host. Nevertheless, the partial nature of this inhibition suggests that multiple pathways promote mammalian cell attachment by B. burgdorferi in vivo. Given the observed increase in cell attachment activity upon growth in the mammalian host, analysis of host‐adapted bacteria will facilitate identification of the cell binding pathways used in vivo.
Post‐ and presynaptic effects of norepinephrine in guinea‐pig colonic submucous plexus
Authors: DOBREVA  , NEUNLIST  , FRIELING  , SCHEMANN
Published: March 2003

Intracellular recording techniques were used to investigate the effects of norepinephrine on submucous neurones in the guinea‐pig distal colon. In 81% of the neurones, pressure microejection of norepinephrine produced a membrane hyperpolarization associated with a decrease in excitability and input resistance. Microejection of clonidine (1 μm) mimicked the norepinephrine‐induced hyperpolarization, whereas both phentolamine (1 μm) and yohimbine (1 μm) reversibly suppressed it. Superfusion of norepinephrine (1 n m– 10 μm) hyperpolarized the cells in a concentration‐dependent manner. Norepinephrine and clonidine (1 n m– 10 μm) caused a concentration‐dependent presynaptic inhibition of stimulus‐evoked cholinergic fast excitatory postsynaptic potential. Slow inhibitory postsynaptic potentials (sISPSs) were induced by focal electrical stimulation of the interganglionic fibre tracts in 43% of the neurones tested. Superfusion of both phentolamine (1 μm) and yohimbine (1 μm) reduced the sIPSPs while prazosin (1 μm) had no significant effect. We concluded that norepinephrine acted post‐ and presynaptically via α2‐adrenoreceptors to have an inhibitory effect on the guinea‐pig colonic submucous. In addition, our study strongly supported the role of norepinephrine as a mediator of the sIPSPs. As a result, norepinephrine would primarily suppress information transfer within the neuronal circuits in guinea‐pig colonic submucosal plexus.
Role of kinin B1 and B2 receptors and mast cells in post intestinal infection‐induced hypersensitivity to distension
Authors: MCLEAN  , PICARD  , GARCIA‐VILLAR  , LAHITTE J. DUCOS DE , MORÉ  , FIORAMONTI  , BUÉNO
Published: March 2003

Distension of the rat intestine causes a capsaicin‐sensitive, pressure‐dependent depressor response which is indicative of nociception. A hypersensitivity of jejunal distension which possibly involves tachykinin NK2 receptors and is restricted to areas with mast cell hyperplagia is observed in rats infected 30 days previously with Nippostrongylus brasiliensis. This study aimed to further investigate the role of mast cells, tachykinins and kinins in this intestinal hypersensitivity. The activity of a mast cell stabilizer (doxantrazole), kinin antagonists (des‐Arg 10‐[Leu9]‐kallidin, B1, HOE 140, B2) and tachykinin antagonists (CP 99, 994, NK1, SR 142801, NK3) were tested against the distension‐induced depressor responses in control and post‐infected rats. The 30‐day post‐infection‐induced hypersensitivity was significantly reduced by the mast cell stabilizer doxantrazole. The hypersensitivity had resolved in 90‐day post‐infected rats when mast cells levels had normalized. Des‐Arg 10‐[Leu9]‐kallidin and HOE 140 did not inhibit the depressor responses in controls but produced a significant inhibition in 30‐day post‐infected rats. CP 99,994 inhibited the depressor responses in post‐infected rats with an equal potency to that in control rats. SR 142801 was inactive in both groups. In conclusion, mast cells and kinin‐mediated nociception appear to be involved in post‐infection intestinal hypersensitivity whereas tachykinin NK1 and NK3 receptors do not.
Alteration of swallowing and oesophageal peristalsis by different initiators of deglutition
Authors: PATERSON
Published: March 2003

It has long been believed that once initiated, the involuntary phase of deglutition follows a stereotypical pattern, that is modified only by ongoing sensory input from the transported bolus. To test the hypothesis that the mode of sensory activation of deglutition can modify the motor response irrespective of bolus characteristics, the mylohyoid, lower oesophageal sphincter (LES) and oesophageal body response to swallows induced in anaesthetized opossums by pharyngeal stroking or superior laryngeal nerve (SLN) stimulation (unilateral and bilateral) were compared. In comparison with unilateral SLN stimulation, swallows triggered by pharyngeal stroking resulted in a greater mylohyoid spike burst and LES relaxation. There was no significant difference in the oesophageal and LES motor response to pharyngeal stroking vs bilateral SLN stimulation, although the mylohyoid response was of greater magnitude with pharyngeal stroking. These studies demonstrate that the motor component of deglutition can be altered by different sensory initiators of swallowing, and provides a possible link between oropharyngeal and oesophageal motor disorders.
Development of a computer‐controlled tensiometer for real‐time measurements of tension in tubular organs
Authors: GREGERSEN  , BARLOW  , THOMPSON
Published: March 2003

A computer‐controlled tensiometer for studying wall tension in tubular organs has been developed. The system consisted of a probe with an inflatable balloon, an impedance planimeter, pressure transducer and amplifier, a pump with RS232 interface and a PC with dedicated software. Circumferential wall tension was computed in real time from pressure and cross‐sectional area measurements (tension measurement mode). Wall tension can be maintained on a preset level or be changed as a step or ramp function by a feedback control of the infusion/withdrawal pump (tension control mode). A software regulator adjusted the volume rate (low volume rate when the computed tension was close to the preset value) to minimize overshoot and oscillation. Validation tests were performed and the technique was applied in the human oesophagus. Volume‐ and tension‐controlled balloon distensions elicited secondary peristalsis of increasing intensity that was decreased significantly by the antimuscarinic agent Hyoscine butyl bromide. In tension control mode Hyoscine butyl bromide caused oesophageal relaxation, i.e. CSA to increase and pressure to decay. Furthermore, pronounced pressure relaxation and tension relaxation were observed during volume‐controlled distension after administration of Hyoscine butyl bromide.
Cortical activation during oesophageal stimulation: a neuromagnetic study
Authors: LOOSE  , SCHNITZLER  , SARKAR  , SCHMITZ  , VOLKMANN  , FRIELING  , FREUND  , WITTE  , ENCK
Published: March 2003

We investigated the neuromagnetic responses to mechanical stimulation of the oesophagus. In six healthy right‐handed volunteers (mean age 31.6 years) the proximal and distal oesophagus were stimulated by electronically controlled pump‐inflation of a silicone balloon once every 4.5–5.5 sec (dwell time 145 msec). The balloon volume was adjusted to induce different sensation levels (i) just above threshold of perception, (ii) strong sensation and (iii) painful sensation. Evoked magnetic brain responses were recorded time‐locked to stimulus onset with a Neuromag‐122TM whole‐head neuromagnetometer and modelled as equivalent current diploe (ECD) sources. ECDs were superimposed on individual magnetic resonance imaging (MRI) scans. Magnetic brain responses following distal oesophageal stimulation were adequately explained by a time‐varying 2–4 dipole model with unilateral or bilateral sources in second somatosensory cortex and later sources in the frontal cortex. With increasing stimulus intensities, latencies of the sources decreased and amplitudes increased. Proximal oesophageal stimulation led to activation of source areas spatially similar to those of distal oesophageal stimulation but with shorter response latencies. Both painful and nonpainful mechanical stimulation of the oesophagus activate the second somatosensory cortex (SII). Evidence for topographic organization of oesophageal afferents in SII is poor.
Identification of the optimal parameters for recording cortical potentials evoked by mechanical stimulation of the human oesophagus
Authors: Hobson  , Sarkar  , Furlong  , Thompson  , Aziz
Published: March 2003

Cortical evoked potentials (CEP) have been recorded in response to both electrical stimulation (ES) and mechanical stimulation (MS) of the oesophagus. While the optimal parameters for recording reproducible oesophageal CEP to ES have recently been established, they have not yet been determined for MS, and reported CEP to MS show considerable variability. This study aimed to identify the optimal parameters required to record reproducible MS induced CEP. CEP were recorded from the vertex (Cz) in six subjects (one female; age range 23–47 years). MS was performed 5 cm above the lower oesophageal sphincter by rapidly inflating a 2‐cm long silicone balloon at a frequency of 0.2 Hz. The rise time to maximum inflation was 165 ms. In order to determine the minimum number of stimuli required to produce optimal signal‐to‐noise quality, we acquired data in runs of 25, 50, 100 and 300 stimuli and to determine the stimulation intensity that produced the shortest latency and the largest amplitude CEP, we averaged four runs of 50 stimuli at five different intensities ranging from sensory threshold to pain. CEP reproducibility was then assessed in three subjects on three separate occasions using parameters determined from these measurements. We found that optimal signal‐to‐noise quality was achieved by averaging four runs of 50 stimuli; that P1 latency was shortest and P1‐N1 amplitude largest at intensities of 75% and pain threshold and that highly reproducible CEP were obtained in all individuals. We conclude that it is possible to obtain highly reproducible oesophageal CEP to MS which can now be compared to those obtained by ES in order to identify which is most suitable for clinical studies.
Arginosuccinate synthetase, arginosuccinate lyase and NOS in canine gastrointestinal tract: immunocytochemical studies
Authors: Daniel  , Wang  , Salapatek  , Mao  , Mori
Published: March 2003

Nitric oxide synthase (NOS) requires the substrate L‐arginine for NO production to support multiple gastrointestinal functions. We asked, ‘Where do enzymes to regenerate
L‐arginine from
L‐citrulline exist?’. We examined loci of immunoreactivities in the canine gastrointestinal tract for arginosuccinate synthetase and arginosuccinate lyase, enzymes that resynthesize
L‐arginine from
L‐citrulline, in relation to the distribution of nNOS immunoreactivity or NADPH‐diaphorase histochemistry. Arginosuccinate synthetase and lyase were present in many neurones and nerve fibres in the myenteric plexus of the lower oesophageal sphincter (LOS), antrum, pylorus, ileum and colon; in the submucosal plexus of ileum and colon; in longitudinal muscle of ileum and colon; and in nerve bundles in circular muscle everywhere. LOS muscle was also immunoreactive for both enzymes. Circular and longitudinal muscle cells of the ileum and colon and cells resembling interstitial cells of Cajal in the deep muscular plexus of the ileum and the submuscular plexus of the colon also appeared immunoreactive. In neurones, arginosuccinate synthetase and nNOS were usually co‐localized. NADPH diaphorase activity was present in LOS and likely in pylorus, but not in muscularis externa of ileum or colon. We conclude that resynthesis of
L‐arginine probably occurs in enteric nerves, interstitial cells of Cajal (ICC) and LOS muscle; also apparently in some cells without NOS to utilize it.
Involvement of tachykinin NK2 receptors in the modulation of spontaneous motility in rat proximal colon
Authors: Mulè  , D’Angelo  , Tabacchi  , Serio
Published: March 2003

The role of endogenous tachykinins and the mechanisms whereby they act on NK2 receptors, modulating spontaneous motility, were investigated in rat isolated proximal colon. The mechanical activity was detected as changes in intraluminal pressure. The NK2 receptor antagonist, MEN 10627, produced a concentration‐dependent reduction of the contraction amplitude. [β‐Ala8]‐neurokinin A(4–10), an NK2 receptor agonist, and [Sar9, Met(O2)11]‐Substance P ([Sar9, Met(O2)11]‐SP), an NK1 receptor agonist, induced a concentration‐dependent contractile response, characterized by an increase in basal tone with superimposed phasic contractions. MEN 10627 antagonized the response to [β‐Ala8]‐neurokinin A(4–10), without affecting that to [Sar9, Met(O2)11]‐SP. Tetrodotoxin (TTX), hexamethonium and Nω‐nitro‐
L‐arginine methyl ester (
L‐NAME) significantly reduced the response to MEN 10627. The NK3 receptor agonist, senktide, was able to activate the nitrergic inhibitory pathway, as it induced a TTX‐and
L‐NAME‐sensitive inhibitory effect. [β‐Ala8]‐neurokinin A(4–10) was able to antagonize the inhibitory response to senktide. These findings suggest that tachykinins acting on NK2 receptors play a role in the modulation of the spontaneous mechanical activity. The mechanism of this action would be, in part, acting directly on the smooth muscle cells, and, in part neurogenic, sustained by nicotinic inputs, and possibly due to inhibition of NO tonic release.
Involvement of spinal calcitonin gene‐related peptide in the development of acute visceral hyperalgesia in the rat
Authors: Gschossmann J. M. , Coutinho S. V. , Miller J. C. , Huebel K. , Naliboff B. , Wong H. C. , Walsh J. H. , Mayer E. A.
Published: March 2003

This study aimed to characterize the role of the neuropeptide calcitonin gene‐related peptide (CGRP) in the development of mechanically induced visceral hyperalgesia. Tonic colorectal distension (CRD) was performed in fasted, conscious male Sprague–Dawley rats. The visceromotor reflex associated with noxious CRD was determined as the number of contractions during each of two consecutive tonic distensions (10 min at 60 mmHg), which were separated by a series of phasic distensions (repeated 15‐s distensions to 80 mmHg at 30‐s intervals). The effect of the CGRP receptor antagonist h‐CGRP8–37 given intrathecally (i.t.) (0.03–3 nmol rat–1) or intravenously (i.v.) (20 μg kg–1 bodyweight [bw]) on the visceromotor response was evaluated. The dose for i.v. administration was chosen based on previous results from similar studies. In addition, the effect of a CGRP monoclonal antibody (6 mg kg–1 bw) given intravenously was evaluated. Compared to the baseline response, a significant increase in the number of abdominal contractions was observed during the second tonic distension. The i.t. application of h‐CGRP8–37 dose‐dependently reduced the numbers of abdominal contractions both during the first and the second tonic distension period, with a maximum effect observed at a peptide concentration of 3 nmol. Intravenous administration of h‐CGRP8–37 or of the CGRP antiserum produced a small reduction of the visceromotor response induced by the second tonic distension and had no effect on colonic compliance. The development of mechanically induced colorectal hyperalgesia by repeated tonic distension involves the spinal release of CGRP, while peripheral release of CGRP plays only a minor role.
Elicitation of transient lower oesophageal sphincter relaxations in response to gastric distension and meal ingestion
Authors: Scheffer R. C. H. , Akkermans L. M. A. , Bais J. E. , Roelofs J. M. M. , Smout A. J. P. M. , Gooszen H. G.
Published: March 2003

Abstract The aim of this study was to compare the effect of graded gastric barostat distension and meal‐induced fundic relaxation on the elicitation of transient lower oesophageal sphincter relaxation (TLOSR). In 15 healthy subjects, stepwise fundic distension and oesophageal manometry were performed simultaneously. Next, the effect of meal ingestion on proximal stomach volume and lower oesophageal sphincter function was studied. During stepwise barostat distension of the proximal stomach, a significant linear correlation between intragastric pressure (r = 0.91; P < 0.01) and the TLOSR rate during inflation and subsequent deflation (r = 0.96; P < 0.01) was found. A similar relationship was found for volume. In addition, after meal ingestion, the TLOSR rate increased significantly from 1.40 ± 3 to 5.4 ± 1.5 h−1 (P < 0.01) and 5.2 ± 1.7 h−1 (P < 0.01), respectively, during the first and second 30‐min postprandially. However, at similar calculated intragastric volumes, barostat distension led to a significantly higher TLOSR rate than the meal. Similarly, distension‐induced increase in gastric wall tension, estimated from the measured bag pressure and volume using Laplace's law, was associated with significantly higher TLOSR rates (P < 0.01). In conclusion, the rate of TLOSRs in healthy volunteers is directly related to the degree of proximal gastric distension and pressure‐controlled barostat distension is a more potent trigger of TLOSRs than a meal. The latter finding suggests that tension receptor activation is an important stimulus for TLOSRs.
Prognostic significance of Ki67, p53 and epidermal growth factor receptor immunostaining in human glioblastomas
Authors: Bouvier‐Labit  , Chinot  , Ochi  , Gambarelli  , Dufour  , Figarella‐Branger
Published: March 2003

gabctgPrognostic significance of Ki67, p53 and epidermal growth factor receptor immunostaining in human glioblastomas

Since glioblastomas in adults are uniformly fatal, evaluation of easily reproducible prognostic criteria which would attempt to define groups of patients is required. However, there is lack of a clear consensus regarding the expression of some markers in the literature. Therefore, an immunohistochemical study was performed to determine the prognostic significance of Ki67, p53, and epidermal growth factor receptor (EGFR) in a retrospective series of 63 glioblastomas. Image analysis was carried out in positive specimens to quantify the immunoprecipitates. p53 and EGFR expression were specifically addressed in the 36 primary glioblastomas reported in this series. In all cases, clinical data (age, Karnofsky performance scale index [KPS] before surgery, extent of surgery) and immunohistochemical features were analysed using univariate and multivariate analysis to ascertain whether any significant correlation exists between [1] EGFR expression [2], p53 accumulation [3], Ki67 labelling index and prognosis (survival time and disease‐free survival time, DFST). The results showed that in this series of glioblastomas, none of these markers had any prognostic value. Among the clinical parameters, a high KPS before surgery was found to be indicative of a shorter DFST and survival time (P<0.05), whereas a younger age at onset and total or subtotal surgical excision were associated with a longer survival (P<0.001 and 0.05, respectively). EGFR protein accumulation was inversely correlated with p53 accumulation (P=0.01). The percentage of the primary glioblastomas expressing EGFR was much lower in our study (33%) than in the literature suggesting that the molecular distinction between primary and secondary glioblastomas is not so clear‐cut.
Skull base chordomas: correlation of tumour doubling time with age, mitosis and Ki67 proliferation index
Authors: Holton J. L. , Steel T. , Luxsuwong M. , Crockard H. A. , Revesz T.
Published: March 2003

The aim of the study was to assess the relationship between the rate of clinical tumour growth and various histological features, including Ki67 labelling index, in skull base chordoma. Cases of skull base chordoma from 19 patients (six female, 13 male; age range 8–63 years) were reviewed and the diagnosis confirmed based on histological and immunohistochemical features. In each biopsy cellularity, pleomorphism, mitotic activity, apoptotic bodies, necrosis and inflammatory cell infiltrate were graded and Ki67 labelling index (LI) calculated as a measure of proliferation. Tumour doubling time was assessed by quantitative analysis of tumour volumes in post‐operative magnetic resonance images and correlated with age, sex, histological parameters and Ki67 LI. It was shown that increasing patient age, the presence of mitotic figures or a Ki67 LI in excess of 6% were associated with faster growing tumours.
Ubiquitin immunoreactivity in presumed spinal interneurones in motor neurone disease
Authors: Stephens B. , Navarrete R. , Guiloff R. J.
Published: March 2003

Previous studies have demonstrated the presence of ubiquitin‐immunoreactivity (Ub‐IR) as inclusions and skeins in motor neurones of both the familial and sporadic forms of motor neurone disease (MND). There is evidence that interneurones also degenerate in MND, but Ub‐IR in ventral horn spinal interneurones has not been studied previously. Here, Ub‐IR was investigated in 1445 presumed interneurones and 1086 presumed motor neurones counted in three random 20‐µm sections of the ventral horn of the third lumbar segment of the spinal cord of each of seven controls and seven patients with MND. The ventral horn was divided into four quadrants; the dorsomedial quadrant contains almost exclusively interneurones and the ventrolateral quadrant largely motor neurones. The neurones were also classified by morphological and size criteria into presumed interneurones (< 25 µm) and presumed motor neurones (≥ 25 µm). Ub‐IR was classified as inclusions, skeins and dispersed cytoplasmic and nuclear staining. Ub‐IR inclusions or skeins were not observed in the controls but 6.6% of neurones (motor neurones and interneurones) showed the presence of dispersed cytoplasm staining and nuclear staining. The incidence of Ub‐IR cytoplasmic and nuclear staining was significantly greater in both motor neurones and interneurones of MND patients than controls. Ub‐IR was less frequent in MND cases in which a great loss of neurones was observed. Ub‐IR was significantly more frequent in motor neurones than interneurones, both in patients and controls. Ub‐IR inclusions and skeins were only observed in motor neurones from MND patients. Ub‐IR inclusions were not observed in presumed spinal interneurones, while skeins were only seen in three out of 565 of these cells (two of them in the dorsomedial quadrant) in two out of seven patients. Thus, although presumed spinal interneurones occasionally revealed Ub‐IR features similar to motor neurones, the rare staining of Ub‐IR skeins and the lack of Ub‐IR inclusions in interneurones in MND suggests that these neurones only occasionally form ubiquitin–protein conjugates. Neuronal size, rather than type, may be important in determining whether ubiquitin–protein conjugates form in the ventral horn neurones in MND.
Prognostic implications of microvessel morphometry in diffuse astrocytic neoplasms
Authors: Korkolopoulou P. , Patsouris E. , Kavantzas N. , Konstantinidou A. E. , Christodoulou P. , Thomas‐Tsagli E. , Pananikolaou A. , Eftychiadis C. , Pavlopoulos P. M. , Angelidakis D. , Rologis D. , Davaris P.
Published: March 2003

Astrocytic brain tumours, particularly malignant astrocytomas, are recognized to be highly vascular neoplasms with potent angiogenic activity. Recent research has shown that quantification of microvessel density (MVD), as a measure of the degree of angiogenesis, constitutes a strong prognostic indicator in patients with astrocytomas. However, the significance of other morphometric aspects of microvessel network has not been tested so far. In this report, histological sections from 70 astrocytomas (grades II to IV), immunostained for CD34, were evaluated by image analysis for the quantification of MVD, total vascular area (TVA), and microvascular branching, as well as several morphometric parameters related to vessel size or shape. Minor axis length increased with grade (P = 0.045) but MVD and TVA presented a peak in grade III (P = 0.033 andP < 0.001, respectively). Size and shape related parameters affected survival in univariate analysis of grade IV and grades II/III, respectively. In multivariate analysis, only branching counts, along with age and grade, were the independent predictors of survival. Although MVD, TVA and branching counts were adversely related to disease‐free survival in grades II and III (univariate analysis), only TVA remained statistically significant in multivariate analysis. It is concluded that TVA and branching counts are prognostically more informative than MVD for patients with diffuse astrocytic tumours.
Features of proliferation and in vitro drug resistance in central primitive neuro‐ectodermal tumours
Authors: Schouten van Meeteren A. Y. N. , Van Der Valk P. , Van Der Linden H. C. , Van Ouwerkerk W. J. R. , Broekhuizen A. J. F. , Huismans D. R. , Loonen A. H. , Veerman A. J. P.
Published: March 2003

The features of proliferation in brain tumours are related with clinical prognosis for several types of brain tumours, especially gliomas. For childhood central primitive neuro‐ectodermal tumours (cPNET), including medulloblastoma, this relation has previously been unclear. The aim of this study is to investigate the relationship between proliferative features of cPNET and in vitro resistance for cytostatic drugs measured with the 3‐4,5‐dimethylthiazol‐2‐yl‐2,5‐diphenyltetrazolium‐bromide (MTT) assay. Tumour material was obtained from 23 surgical specimens of cPNET. The expression of the proliferation markers Ki‐67, proliferating cell nuclear antigen (PCNA) and cyclin D1 was determined with immunohistochemistry, while S‐phase and DNA ploidy were analysed by flowcytometric analysis cell scan (FACS). The in vitro resistance for 10 cytostatic drugs was determined with the MTT assay. Drug resistance levels were available in 19 (83%) of the 23 samples with a complete profile of 10 cytostatic drugs tested in 14 samples. An excellent correlation in drug resistance scores was found between pharmacologically related drugs. The Ki‐67 staining in 20 samples varied from 10 to 60% and from 30 to 100% for PCNA. Cyclin D1 staining was negative in 11 out of 18 samples. The S‐phase in 16 samples ranged from 2 to 16%. Increased staining of Ki‐67 was related with actinomycin D sensitivity (r −.603; P=0.022), while cells with a higher S‐phase percentage were more resistant to ifosfamide (r .952; P<0.0001). In vitro drug resistance testing of central primitive neuro‐ectodermal tumours (PNET) is feasible with the MTT assay. Ifosfamide resistance was related with increased Ki‐67 and S‐phase percentage of the tumour cells, while increased Ki‐67 was also related with actinomycin D sensitivity. These findings suggest a cell cycle dependent activity of cytostatic drugs in vitro.
Muscle pathology in dysferlin deficiency
Authors: Fanin M. , Angelini C.
Published: March 2003

Dysferlin deficiency is being increasingly recognized in limb‐girdle dystrophy and distal myopathy but its role in the development of muscle pathology is still poorly understood. For this purpose, 26 muscle biopsies from 25 dysferlinopathy patients were analysed by routine histochemistry and by immunohistochemistry with eight different antibodies, and scored for inflammatory response and type of cell infiltrate, fibre degeneration and regeneration, fibre type composition and severity of histopathological changes. In cases with an advanced‐stage dystrophic pattern we observed type 1 fibre predominance exceeding 80%, suggesting a selective loss of type 2 fibres or a conversion process.

The extent of muscle fibre regeneration and degeneration in dysferlinopathy was intermediate between sarcoglycanopathy and Duchenne dystrophy or myositis, suggesting a rather aggressive course of the disease. An increased inflammatory response was observed in the majority of our patients (16/26), who also showed an active dystrophic pattern. Type and localization of cellular infiltrates suggest that inflammatory reaction is secondary to necrosis. Major histocompatibility complex (MHC) class I molecules were overexpressed in dysferlinopathy, mainly in association with fibre phagocytosis and regeneration; their occasional expression in non‐necrotic fibres might represent a marker of ongoing necrosis. Muscle inflammation might be triggered by the structurally altered membrane consequent to dysferlin defect.
Congenital arteriovenous fistula of the brain with an atrial septal defect: case report
Authors: Hortobágyi T. , Szüts Á. , Csenki M. , Bódi I.
Published: March 2003

Introduction:  Aneurysmal malformation of the vein of Galen (AVG) is caused by an arteriovenous fistula (AVF) between the basal arteries and deep venous sinuses of the brain. Congenital forms of AVG are potentially fatal, leading to a left‐to‐right shunt and cardiomegaly, and the death is most commonly as a result of cardiac failure. We present a case with an AVF of brain with an ASD.

Material and methods:  A mature male baby born at gestational week 38 was admitted to PICU with tachydyspnoe 4 h after birth. Ultrasound (US) and computed tomography scans of the brain detected a large bilateral AVF with dilated basal arteries and venous sinuses (sinus petrosus, sinus confluens, sinus transvs. and sagittal inferior sinus), hydrocephalus and brain atrophy. Cardiac US showed right ventricular hypertrophy, persistent ductus Botall and ASD. The patient died of cardiac failure 6 days after birth.

Results:  Autopsy examination of the brain showed dilatation of the vein of Galen and venous sinuses, a large conglomerate of dilated blood vessels in the midline and left occipital lobe, oedema and hydrocephalus. Examination of the heart confirmed Us findings and showed an ostium secundum ASD. Histologically, the occipital mass revealed features of an AVF, consistent with AVG. Chronic ischaemic lesions with ferruginated neurons were also present.

Conclusions:  The presence of chronic hypoxic changes in the brain suggests intrauterine damage as a result of a congenital AVF. The left‐to‐right shunt, in addition to causing cardiomegaly, may also have interfered with the development of the atrial septum, leading to an ostium secundum ASD, aggravating the clinical course.
Squirrel monkeys in Costa Rica: drifting to extinction
Authors: Boinski Sue , Jack Katharine , Lamarsh Craig , Coltrane Jessica A.
Published: March 2003

Central American squirrel monkeysSaimiri oerstediiare limited to Costa Rica and Panama, and have never been abundant. The Costa Rican population is now decimated. Based on our survey of squirrel monkeys throughout a large portion of the Costa Rican range of this species in 1996, we can confirm that at least 1246 squirrel monkeys remain in 26 spatially dispersed localities. Despite probable undercounts of squirrel monkeys within sites and potentially missed localities, the total population size should be considered far below a size that would provide longterm genetic viability. Deforestation and habitat fragmentation spurred by agricultural and tourism development are the familiar culprits contributing to this decline. Our strong recommendation is that future conservation efforts be targeted at the level of each specific locality, perhaps recruiting local, national and international sponsors. A focused strategy would allow management efforts to be tailored to the circumstances specific to each site and thus allocate scarce resources more efficiently.
The population status of chameleons within Ranomafana National Park, Madagascar, and recommendations for future monitoring
Authors: Jenkins Richard K. B. , Brady Lee D. , Huston Kieron , Kauffmann Juliet L. D. , Rabearivony Jeanneney , Raveloson Georges , Rowcliffe J. Marcus
Published: March 2003

Malagasy chameleons are threatened by the relentless pace of habitat destruction. Their great popularity amongst herpetoculturalists has also resulted in collection for international animal markets. Most previous fieldwork has focused on the compilation of much needed species inventories, but little attention has been given to estimating chameleon population densities. This lack of information prevents a reliable assessment of the effects ofhabitat loss and direct exploitation on wild populations. A simple and repeatable methodology for the monitoring of chameleon populations is therefore urgently required. The present study developed survey techniques based on distance sampling within an area of relatively undisturbed rain forest at Ranomafana National Park. In total 394 individuals from six species were recorded and population densities (± SE) of 27.2 ± 5.4/ha Brookesia spp. and 21.4±4.0/ha Calumma spp. were estimated using the computer program DISTANCE. The authors propose that monitoring of chameleons in areas subject to different threats should begin immediately using the methods outlined in this paper.
First steps towards the conservation of the microendemic Patagonian frogAtelognathus nitoi
Authors: Úbeda Carmen , Zagarese Horacio , Diaz Mónica , Pedrozo Fernando
Published: March 2003

Atelognathus nitoiis a microendemic leptodactylid frog restricted to the area surrounding the pond Laguna Verde in the Nahuel Huapi National Reserve, north-west Patagonia, Argentina. Its habitat is potentially threatened by a number of anthropogenic and natural factors. The aim of this study was to obtain basic knowledge of the biology and habitat of the species, which would be useful for selecting management measures to ensure its conservation. The area was surveyed during all four seasons in 1996 and 1997 and Laguna Verde was sampled intensively in winter and in summer.Atelognathus nitoiis distributed patchily. The preferred microhabitats of adults and juveniles are the most humid areas of the forest. Reproduction and larval development occurs only in lentic environments. Laguna Verde is the only known permanent waterbody suitable for reproduction every year. During rainy years reproduction can also take place in temporary ponds. Action towards the conservation ofA.nitoishould be aimed at preserving both the terrestrial and aquatic habitats. Laguna Verde appears to be a key site for theA. nitoisource population and plays an essential part in the conservation of this species. In terrestrial habitats it is vital to preserve the heterogeneity of the lower strata in the forest. The knowledge gained through this study has allowed the authors to suggest protective measures to mitigate or eliminate the impact of certain stressors on the ecology of the species.
Przewalski's horse—adaptation to semi-wild life in desert conditions
Authors: Pereladova O. B. , Sempéeré A. J. , Soldatova N. V. , Dutov V. U. , Fisenko G. , Flint V. E.
Published: March 2003

In 1989 an experiment was started at the Bukhara Breeding Centre, Kyzylkum Desert, Uzbekistan, to discover whether zoo-bred Przewalski's horses Equus przewalskiicould adapt to semi-wild desert conditions. One stallion and four mares of different ages were released into a 5126-ha fenced area and monitored over a period of 17 years. This paper presents the information gained from the studies concerning home ranges, interactions with other ungulate species, adaptation to new food resources and comparative changes in daily activity. The results of breeding and changes in the structure of the group are also presented. The horses appeared to adapt well to the new conditions and there appeared to be no negative effects of interspecific interaction with introduced kulans Equus hemionus kulan in the release area.
Conserving the African wild dog Lycaon pictus. II. Is there a role for reintroduction?
Authors: Woodroffe Rosie , Ginsberg Joshua R.
Published: March 2003

African wild dogs Lycaon pictus have been extirpated across most of West and central Africa, and greatly depleted in eastern and southern Africa. Given an urgent need for population recovery, especially in West and central Africa, this paper discusses the possibilities for using reintroduction to re-establish wild dog populations. Reintroduction is probably now technically possible, as long as release groups include wildcaught animals; several past attempts failed because captive-reared animals lacked skills needed to survive in the wild. However, reintroduction has only a limited role to play in wild dog conservation. Ideally, it should involve animals of the appropriate local genotype. Limited genetic data indicate that wild dogs from West and central Africa may be distinct from those in eastern and southern Africa. Because there are no wild dogs with West or central African genotypes in captivity, and no wild populations in the region large enough to be harvested for translocation, future reintroductions might have to use animals with non-native genotypes. In addition, there appear to be no suitable sites for wild dog reintroduction in West or central Africa, and few in eastern and southern Africa. Releases currently planned in the Republic of South Africa will be locally valuable, but will not establish a population likely to remain viable without intensive management in perpetuity. For these reasons, protecting remaining wild dog populations currently represents a better investment than any attempt at reintroduction.
Elephant corridors in India: lessons for other elephant range countries
Authors: Johnsingh A. J. T. , Williams A. Christy
Published: March 2003

The conservation status of five elephant corridors in different regions of India is discussed. Elephants have not used the 13-km-wide corridor between Ariankavu and Thenmalai, in the southern portion of the Western Ghats for several decades because a rail track and road, both of which are bordered by human habitations, cross it. The future of the Chilla–Motichur and Rajaji–Corbett corridors, which hold the Rajaji–Corbett elephant population in north-west India as one entity, is bleak. It is still possible for elephants to use the Kallar–Jaccanari corridor linking the 4000-strong elephant population of northern and southern Nilgiri Biosphere Reserve in southern India. It may be possible to save the Siju–Rewak corridor, which connects the elephant populations on either side of the River Simsang in north-east India. The authors suggest that other Asian countries that have elephant populations and that are capable of establishing large conservation units, should have master plans that should detail possible developmental activities around existing wildlife habitats. Establishing vast protected areas for large mammals, however, would need political will and regular communication among the nations' development planners, wildlife managers and researchers.