bluuebunny/crossref_metadata_2025 huggingface dataset:
Microarray expression profiling: capturing a genome‐wide portrait of the transcriptome
Authors: Conway Tyrrell , K. Gary , Schoolnik
Published: March 2003

The bacterial transcriptome is a dynamic entity that reflects the organism's immediate, ongoing and genome‐wide response to its environment. Microarray expression profiling provides a comprehensive portrait of the transcriptional world enabling us to view the organism as a ‘system’ that is more than the sum of its parts. The vigilance of microorganisms to environmental change, the alacrity of the transcriptional response, the short half‐life of bacterial mRNA and the genome‐scale nature of the investigation collectively explain the power of this method. These same features pose the most significant experimental design and execution issues which, unless surmounted, predictably generate a distorted image of the transcriptome. Conversely, the expression profile of a properly conceived and conducted microarray experiment can be used for hypothesis testing: disclosure of the metabolic and biosynthetic pathways that underlie adaptation of the organism to chang‐ing conditions of growth; the identification of co‐ordinately regulated genes; the regulatory circuits and signal transduction systems that mediate the adaptive response; and temporal features of developmental programmes. The study of bacterial pathogenesis by microarray expression profiling poses special challenges and opportunities. Although the technical hurdles are many, obtaining expression profiles of an organism growing in tissue will probably reveal strategies for growth and survival in the host's microenvironment. Identifying these colonization strategies and their cognate expression patterns involves a ‘deconstruction’ process that combines bioinformatics analysis and in vitro DNA array experimentation.
The modular structure of Escherichia coli threonyl‐tRNA synthetase as both an enzyme and a regulator of gene expression
Authors: Caillet Joël , Nogueira Teresa , Masquida Benoît , Winter Flore , Graffe Monique , Dock‐Brégeon Anne‐Catherine , Torres‐Larios Alfredo , Sankaranarayanan Rajan , Westhof Eric , Ehresmann Bernard , Ehresmann Chantal , Romby Pascale , Springer Mathias
Published: March 2003

In addition to its role in tRNA aminoacylation, Escherichia coli threonyl‐tRNA synthetase is a regulatory protein which binds a site, called the operator, located in the leader of its own mRNA and inhibits translational initiation by competing with ribosome binding. This work shows that the two essential steps of regulation, operator recognition and inhibition of ribosome binding, are performed by different domains of the protein. The catalytic and the C‐terminal domain of the protein are involved in binding the two anticodon arm‐like structures in the operator whereas the N‐terminal domain of the enzyme is responsible for the competition with the ribosome. This is the first demonstration of a modular structure for a translational repressor and is reminiscent of that of transcriptional regulators. The mimicry between the operator and tRNA, suspected on the basis of previous experiments, is further supported by the fact that identical regions of the synthetase recognize both the operator and the tRNA anticodon arm. Based on these results, and recent structural data, we have constructed a computer‐derived molecular model for the operator‐threonyl‐tRNA synthetase complex, which sheds light on several essential aspects of the regulatory mechanism.
SB‐207266: 5‐HT4 receptor antagonism in human isolated gut and prevention of 5‐HT‐evoked sensitization of peristalsis and increased defaecation in animal models
Authors: SANGER  , BANNER  , SMITH  , WARDLE
Published: March 2003

SB‐207266 is a new 5‐HT4 receptor antagonist which in a pilot study reduced the symptoms of irritable bowel syndrome. To help validate this and further studies, we examined the ability of SB‐207266 to antagonize at the human 5‐HT4 receptor (human isolated intestine) and to affect the mechanisms of peristalsis (guinea‐pig isolated ileum) and defaecation (conscious, fed mice). In the human intestine, the potency of 5‐HT4 receptor antagonism (pKB 9.98) was similar to that previously demonstrated using a guinea‐pig model of the receptor, validating the use of SB‐207266 in clinical trials. In each of the animal models, SB‐207266 did not affect normal patterns of intestinal motility measured in the absence of exogenous 5‐HT. However, SB‐207266 10–1000 p
M concentration‐dependently antagonized the ability of 5‐HT (0.1 μM) to sensitize the peristaltic reflex and lower the distension threshold at which peristalsis was evoked. In mice, oral or subcutaneous (s.c.) doses of SB‐207266 dose‐dependently prevented the ability of the 5‐HT precursor, 5‐hydroxytryptophan (5‐HTP, 10 mg kg−1 s.c.) to increase both the rate of defaecation of formed faecal pellets and their fluid content. SB‐207266 was maximally active at 10 μg kg−1 s.c. and 1000 μg kg−1 p.o. SB‐207266 may therefore represent a new class of therapeutic agent, capable of preventing the actions of an important sensitizer of gut function.
Altered myoelectrical activity in noninflamed ileum of rats with colitis induced by trinitrobenzene sulphonic acid
Authors: AUBE  , CHERBUT  , BARBIER  , XING  , ROZE  , GALMICHE
Published: March 2003

Changes in gastric emptying and orocaecal transit time in patients with ulcerative colitis suggest that disturbances in gut motility may not be restricted to inflamed sites. This study sought to characterize changes in the motility of noninflamed ileum in a rat colitis model and to explore the mechanism(s) potentially involved. The myoelectrical activity of the ileum was recorded in rats with trinitrobenzene sulphonic acid (TNBS)‐induced colitis. The degree of ileal and colonic inflammation was assessed by quantification of macroscopic damage and myeloperoxidase activity (MPO). The effect on ileal motility of pretreatment with atropine, indomethacin and NG‐nitro‐
L‐arginine‐methyl ester (L‐NAME) was investigated. TNBS‐induced inflammation was restricted to the distal colon, as evidenced by morphological scores and MPO. Colitis was associated with increased frequency of ileal migrating motor complexes, characterized mainly by a decrease in the duration of phases I and III. The occurrence of ileal giant migrating complexes remained unchanged. The myoelectrical changes observed in the ileum persisted after treatment with atropine, indomethacin and L‐NAME. Distal colitis is associated with abnormal myoelectrical activity in the noninflamed ileum of rats. Neither acetylcholine nor prostaglandins and nitric oxide seem to be involved.
Mechanical activity of small and large intestine in normal and mdx mice: a comparative analysis
Authors: MULÉ  , D'ANGELO  , TABACCHI  , AMATO  , SERIO
Published: March 2003

The aim of this study was to compare the motor pattern (recorded as changes in intraluminal pressure) of isolated duodenum and proximal colon between dystrophic mdx and normal mice. When duodenal recordings from control preparations were compared with mdx mice there was no significant difference in the spontaneous motor pattern, responses to electrical nerve stimulation or sensitivity to pharmacological agents. Colonic segments from mdx mice showed a more complex motor pattern, consisting of contractions with amplitude and frequency similar to those of controls and by additional contractions with lower amplitude and higher frequency. Moreover, 70% of the colonic preparations from mdx mice developed active tone. TTX (1 μM), both in control and in mdx mice, changed the motor pattern, revealing regular rhythmic contractions similar in both preparations. L‐NAME (100 μM) in both preparations increased contractile activity, revealing additional low contractions in control and potentiating them in mdx colon. In both control and mdx mice, inhibitory responses elicited by electrical field stimulation (EFS) were significantly attenuated by L‐NAME. Our results provide evidence for the presence of a different motor pattern in mdx proximal colon and suggest that mdx mice can be considered a suitable animal model for investigating the dystrophic process.
Control systems of gastrointestinal motility are immature at birth in dogs
Authors: Daniel  , Wang Yu‐Fang
Published: March 2003

Networks of interstitial cells of Cajal (ICC) in the myenteric plexus (Myp) or circular muscle (CM) function as pacemakers for gastrointestinal slow waves. ICC in contact with muscle and closely associated with nerves in the CM may mediate inhibitory neurotransmission. We wondered if ICC in Myp and CM and their connections are immature at birth and mature first in the proximal gut in association with nerves. Tissues from lower esophageal sphincter (LES), pylorus (PYL), small intestine (SI) and colon (CO) of 18 term fetal dogs taken from six females were fixed and prepared for ultrastructural examination and studied. Ganglia were present where expected in the Myp and submucous plexus (SMP). ICC cells were present in the Myp of PYL, SI and CO and appeared to have normal relationships to the outer border of CM as in adults. ICC in CM were found associated with nerves in the LES and in PYL, but not in SI or CO. However, axons in CM were everywhere usually free of glial covering, indicating ongoing migration or development. No organized deep muscular plexus (DMP) in SI or submuscular plexus (SP) in colon was present. Visible gap junctions were absent everywhere except for very rare ones between circular muscle cells. We conclude that at birth the neural and ICC networks of CM are more immature in intestine and colon than in oesophagus and stomach. Development of nerve and ICC of CM in oesophagus and stomach apparently precedes that in the remaining gut. However networks in these regions have not achieved adult organization and ICC and smooth muscle cells are anatomically poorly coupled. These findings suggest the reasons that gut motility at birth will not be adult in pattern are because ICC, nerve and muscle control systems are not fully differentiated. Further developmental delays in ICC and nerve maturation could have serious consequences for feeding of infant animals.
The search for the origin of rhythmicity in intestinal contraction; from tissue to single cells
Authors: Huizinga  , Robinson  , Thomsen
Published: March 2003

More than a century ago, rhythmic propulsive contractile activity was observed in the intestine after blockade of nerve conduction, thus demonstrating a form of peristalsis that appeared to be under myogenic control. During this century, light and electron microscopic investigations provided the hypothesis that interstitial cells of Cajal (ICC) could be the cells of origin for this rhythmicity. In recent years, physiological studies demonstrated a link between the presence of electrical slow wave activity and the presence of ICC. The recognition that the ICC cell membrane harbours the Kit protein sparked rapid advancement in ICC research, and has been essential in the identification of ICC in tissue and in culture through Kit immunohistochemistry and kit mRNA reverse transcriptase polymerase chain reaction (RT‐PCR). With these techniques, electrophysiology was carried out on positively identified single ICC in culture. These methods revealed that single ICC generate spontaneous rhythmic inward currents and slow waves in membrane potential, thus providing strong evidence that ICC generate the electrical pacemaker activity for the gut musculature.
Retrograde tracing of enteric neuronal pathways
Authors: Brookes S. J. H.
Published: March 2003

Neuroanatomical tracing techniques, and retrograde labelling in particular, are widely used tools for the analysis of neuronal pathways in the central and peripheral nervous system. Over the last 10 years, these techniques have been used extensively to identify enteric neuronal pathways. In combination with multiple‐labelling immunohistochemistry, quantitative data about the projections and neurochemical profile of many functional classes of cells have been acquired. These data have revealed a high degree of organization of the neuronal plexuses, even though the different classes of nerve cell bodies appear to be randomly assorted in ganglia. Each class of neurone has a predictable target, length and polarity of axonal projection, a particular combination of neurochemicals in its cell body and distinctive morphological characteristics. The combination of retrograde labelling with targeted intracellular recording has made it possible to target small populations of cells that would rarely be sampled during random impalements. These neuroanatomical techniques have also been applied successfully to human tissue and are gradually unravelling the complexity of the human enteric nervous system.
Effects of the enterokinetic prucalopride (R093877) on colonic motility in fasted dogs
Authors: Briejer M. R. , Prins N. H. , Schuurkes J. A. J.
Published: March 2003

The novel enterokinetic drug prucalopride was tested at various intravenous and oral doses in fasted dogs to assess: (i) the effects on colonic contractile motility patterns; and (ii) the mediation of these effects by 5‐hydroxytryptamine (5‐HT4) receptors. Colonic motility patterns were assessed in conscious dogs with four chronically implanted strain‐gauge force transducers that were sutured on the serosal side of the colon. Prucalopride altered colonic contractile motility patterns in a dose‐dependent fashion by stimulating high‐amplitude clustered contractions in the proximal colon and by inhibiting contractile activity in the distal colon. Prucalopride was equipotent after oral and intravenous administration, as reflected by the values for the effective dose that induced 50% of maximum effect (95% confidence limits): 0.04 mg kg–1 p.o. (0.01–0.1 mg kg–1) and 0.01 mg kg–1 i.v. (0.006–0.04 mg kg–1). Prucalopride also caused a dose‐dependent decrease in the time to the first giant migrating contraction (GMC); at higher doses of prucalopride, the first GMC generally occurred within the first half‐hour after treatment. Subcutaneous pretreatment with the 5‐HT4 receptor antagonist GR125487 (40 μg kg–1 bodyweight) completely prevented the effects of orally administered prucalopride (0.31 mg kg–1 bodyweight). Prucalopride, given orally or intravenously, alters colonic motility in the fasted conscious dog in a dose‐dependent fashion. It induces GMCs and causes proximal colon stimulation and distal colon inhibition of contractile motility patterns by stimulating 5‐HT4 receptors.
Calcium signalling and removal mechanisms in myenteric neurones
Authors: VANDEN BERGHE P. , MISSIAEN L. , JANSSENS J. , TACK J.
Published: March 2003

To characterize further the Ca2+ signalling mechanisms of myenteric neurones, we studied the effect of thapsigargin, a blocker of the Ca2+‐store ATPase, and the mechanisms involved in restoring the intracellular Ca2+ concentration ([Ca2+]i) after activation. Thapsigargin (5 × 10−6 mol L−1) induced an oscillatory [Ca2+]i response in 86.6% of the neurones (n=276), which was blocked by the removal of extracellular Ca2+ and by ω‐conotoxin MVIIA (5 × 10−7 mol L−1). The IP3‐blocker, 2‐aminoethyl‐diphenyl‐borate (75 × 10−6 mol L−1), blocked or reduced the responses in 74.5% of the neurones. The oscillatory responses induced by the depletion of Ca2+ stores suggest that myenteric neurones might recruite N‐type Ca2+ channels as a refill mechanism. Thapsigargin pretreatment increased the amplitude, the upstroke and duration of the K+‐induced [Ca2+]i responses. Mitochondrial blockers (rotenone and antimycin/oligomycin) also prolonged the responses, but without affecting the amplitude. Furthermore, it was found that for high [Ca2+]i, the thapsigargin‐sensitive Ca2+ uptake was crucial, while mitochondrial blockade affected the Ca2+ uptake over a wide range of concentrations. The Ca2+‐sequestering components might also have been compensating for each other, as most drugs only delayed and not inhibited Ca2+ removal.
The role of remote gut inflammation in duodenojejunal dysmotility
Authors: LE BLANC‐LOUVRY I. , DENIS P. , DUCROTTÉ P.
Published: March 2003

The aim of this prospective study was to determine the role of remote inflammation of the gut on duodenojejunal motor status by comparing patients with acute cholecystitis (AC) to those with biliary colic (BC). Thirty‐six gallstone patients (11 AC and 25 BC) were explored. Manometric recordings were performed during fasting and after a 750‐kcal meal and ended by an intravenous injection of 100 mg trimebutine. Patient data were compared to those of 20 healthy controls. Phases III were more frequently absent in AC patients than in BC patients (P < 0.01) and controls (P < 0.05). When phase III characteristics were similar between the AC and BC group, the phase III amplitude was lower in both groups than in controls (P < 0.0001). After the meal, the mean motor index in the jejunum expressed by the area under the curve (AUC) per 30‐min period was higher in the AC group than in BC group and controls (P < 0.05). Specific motor phenomena were observed after the meal. In particular, propagating clusters of contractions (PCCs) were more frequent in AC patients than in BC (P < 0.05) and controls (P < 0.01). A lack of the expected decrease in the AUC during recording occurred with the same frequency in the AC and BC groups but was more frequent in patients than in controls (P < 0.05). In 8/11 patients in the AC group with duodenojejunal tracings before and 3 months after surgery, preoperative motor disturbances disappeared in 5/8 patients and improved in 3/8 patients. The higher frequency of duodenojejunal motor disturbances especially after a meal in patients with AC and their disappearance in most of the pateints after removal of the infected gallbladder suggest that remote inflammation of the gut affects duodenojejunal motility.
Ca2+ involvement in the action potential generation of myenteric neurones in the rat oesophagus
Authors: DE LAET A. , CORNELISSEN W. , ADRIAENSEN D. , VAN BOGAERT P‐P. , SCHEUERMANN D. W. , TIMMERMANS J‐P.
Published: March 2003

Intracellular recordings were used to study the physiological behaviour of rat oesophageal myenteric neurones, which are embedded in striated muscle. Injection of depolarizing pulses evoked action potentials with a clear `shoulder' in all neurones. This shoulder disappeared under low Ca2+/high Mg2+ conditions. Tetrodotoxin (TTX; 1 μmol L−1) did not impede spike firing, whereas under combined TTX and low Ca2+/high Mg2+ conditions the action potentials were completely abolished, indicating that TTX‐ resistant action potentials are mediated by a Ca2+ current. Further experiments with ω‐conotoxin GVIA (100 nmol L−1) revealed that these Ca2+ currents enter the cell via N‐type voltage‐activated Ca2+ channels (see also accompanying paper). Tetraethylammonium (10 mmol L−1) caused broadening of the action potentials, which probably resulted from prolonged Ca2+ influx due to blockade of the delayed rectifier K+ channel. Although Ca2+ appears to be involved in the spike generation of all rat oesophageal myenteric neurones, only a minority (14%) shows a slow afterhyperpolarization. Thus, no strict correlation exists between the presence of a shoulder and a slow afterhyperpolarization. Furthermore, morphological identification of 25 of the impaled neurones revealed that there was no strict correlation between morphology and electrophysiological behaviour. Consequently, rat oesophageal myenteric neurones appear to differ in several aspects from myenteric neurones in smooth muscle regions of the gastrointestinal tract.
Immunohistochemical localization of voltage‐activated calcium channels in the rat oesophagus
Authors: DE LAET A. , ADRIAENSEN D. , VAN BOGAERT P‐P. , SCHEUERMANN D. W. , TIMMERMANS J‐P.
Published: March 2003

Voltage‐activated calcium channels play an important role in the physiology of the enteric nervous system. To determine which types of voltage‐activated calcium channels are present in the rat oesophagus, an immunohistochemical study was performed using specific antibodies for the alpha1 subunits of Cav2.1 (P/Q‐type), Cav2.2 (N‐type), Cav1.2 and Cav1.3 (L‐type) calcium channels. All myenteric cell bodies showed Cav2.2 immunoreactivity, whereas labelling for this N‐type channel was absent in nerve fibres. Cav1.2 immunoreactivity was found on nerve fibres in the myenteric plexus and on fibres innervating the striated muscle of the rat oesophagus, whereas no labelling was detected on neuronal somata. Immunoreactivity against Cav1.3 was not detected in the myenteric plexus or at the level of the striated muscle. Labelling for Cav2.1 was absent at the level of the myenteric plexus, but present in the striated muscle layer at the level of the motor endplates. Comparison with recent literature data from rat small intestine reveals region‐specific distribution patterns of the various subtypes of voltage‐activated calcium channels within the enteric nervous system. In addition, the present immunohistochemical data corroborate our physiological data (see accompanying paper), which indicate that the Cav2.2 (N‐type) channel is the predominant channel involved in the generation of the calcium‐dependent action potential evoked by intrasomatic depolarizing current pulses in all rat oesophageal myenteric neurones.
Electrical behaviour of interleukin‐1 beta (IL‐1β) and prostaglandin‐E2 (PGE2) on colonic myenteric neurones
Authors: Kelles A. , Janssens J. , Tack J.
Published: March 2003

Abstract
 Intracellular recordings were used to examine the effects on electrical and synaptic behaviour of interleukin (IL)‐1β and prostaglandin E2(PGE2) on myenteric neurones of the guinea‐pig colon. Application of IL‐1β and PGE2resulted in a concentration‐dependent slow depolarization with enhanced spike discharge in, respectively, 45% (21/47) and 83% (33/41) of the impaled colonic neurones. Administration of IL‐1β in three neurones (6%) elicited a hyperpolarization. Responses remained during tetrodotoxin application, indicative of a direct effect of both substances on the impaled neurones. The effects of IL‐1β remained in the presence of indomethacine, a prostaglandin synthase inhibitor. Responses were seen in both nitric oxide synthase‐ and choline acetyl transferase‐immunoreactive neurones. IL‐1β evoked a 26% reduction of the fast excitatory postsynaptic potential. These results indicate that the application of IL‐1β and PGE2evoke direct excitatory actions on a subset of myenteric neurones. For IL‐1β, direct inhibition and presynaptic inhibition of the fast excitatory postsynaptic potential has also been found. In the distal colon, responses to IL‐1β are not mediated through PGE2pathways.
Small intestinal transections decrease the occurrence of tapeworm‐induced myoelectric patterns in the rat
Authors: Dwinell K. L. , Bass P. , Zou F. , Oaks J. A.
Published: March 2003

Abstract
 Luminal infection by the noninvasive tapeworm, H. diminuta, alters rat small intestinal myoelectric activity. The significance of continuity between small intestinal enteric nervous system (ENS) and that of both the stomach/pylorus and colon/caecum regarding the induction of tapeworm‐altered myoelectric patterns was evaluated. A total of 32 rats were implanted with four serosal electrodes placed at sites in the duodenum through the mid‐jejunum. Sixteen of the 32 rats underwent intestinal transections and anastomoses at both the duodenum and ileum. After recording myoelectrical activity of both normal and transected intestines, eight rats from each group (normal and transected) were infected with H.diminuta. Phase III frequency, duration of the migrating myoelectric complex (MMC), slow wave frequency, percentage of slow waves associated with spike potentials and the occurrence of the the two tapeworm‐initiated myoelectric patterns, repetitive bursts of action potentials (RBAP) and sustained spike potentials (SSP), were measured. In infected rats, the frequency of the RBAP and SSP electric patterns were significantly reduced by the double transection. Intestinal transection did not affect the other changes caused by infection, such as decreased MMC phase III frequency and percentage of slow waves associated with spike potentials. In conclusion, a small intestinal ENS in continuity with other segments of the GI tract is required to generate maximal numbers of tapeworm‐induced SSP and RBAP myoelectric activity in the small intestine of the rat.
NF‐kB immunoreactivity is observed in association with βA4 diffuse plaques in patients with Alzheimer’s disease
Authors: Ferrer  , Martí  , López  , Tortosa
Published: March 2003

Transcription factor NF‐kB is widely expressed in the nervous system and, particularly, in synaptic terminals. Increased NF‐kB expression in synaptosomes has been observed as a result of activity, and βA4 deposition. In the present study we have examined NF‐kB immunoreactivity, by means of NF‐kB p65 immunohistochemistry, in the brains of seven patients with Alzheimer’s disease, two patients with Creutzfeldt‐Jakob disease associated with PrP amyloid deposition, and seven age‐matched controls. Our purpose was to examine possible NF‐kB induction associated to βA4 or PrP deposition in these diseases. Punctate NF‐kB immunoreactivity was constantly found in the neuropil of diffuse βA4 deposits but not in dystrophic neurites of senile plaques. In addition, NF‐kB immunoreactivity was found in the nuclei of neurons, but not in the nuclei of reactive astrocytes, in the vicinity of diffuse plaques, thus suggesting NF‐kB translocation to the nucleus. Finally, a few neurons with neurofibrillary degeneration showed increased cytoplasmic NF‐kB immunoreactivity probably secondary to abnormal compartmentation or impaired transport of NF‐kB. No similar modifications in NF‐kB immunoreactivity were observed in association with PrP deposits in patients with Creutzfeldt‐Jakob disease. Since it has been suggested that the presence of NF‐kB in synapses may indicate the existence of a new pathway of gene transcription, the present results support the concept that this pathway may be activated by the deposition of βA4 in diffuse plaques in Alzheimer’s disease.
Differential expression of MHC class II molecules by microglia and neoplastic astroglia: relevance for the escape of astrocytoma cells from immune surveillance
Authors: Tran  , Wolz  , Egensperger  , Kösel  , Imai  , Bise  , Kohsaka  , Mehraein  , Graeber
Published: March 2003

There is increasing evidence that microglia serve as antigen presenters in the human CNS. Although the occurrence of MHC class II immunoreactive cells has been reported in astrocytic gliomas, the relative contribution of microglia to this cell population has not been studied in detail. Using computer‐assisted image analysis, we have investigated the expression of MHC class II molecules and of the microglia/macrophage markers Ki‐M1P, RCA‐1, KP1 and iba1, in 97 astrocytic gliomas comprising all WHO grades to answer the question whether there is a correlation between tumour grade and the number of MHC class II positive microglia/macrophage profiles. Microglia expressing MHC class II were common in astrocytomas and anaplastic astrocytomas but rare in pilocytic tumours although there was significant variation within each group. MHC class II immunoreactivity was reduced in highly cellular areas of glioblastomas where large numbers of cells expressing macrophage markers were still present. Thus, there was no simple relationship between tumour grade and microglial/macrophage MHC class II expression. In addition, up to 55% of astrocytic gliomas contained MHC class II immunoreactive tumour cells. Microglia but not tumour cells were found to express the BB1/B7 costimulator. We conclude that microglia in astrocytic gliomas are well equipped to function as antigen presenting cells. Yet, neoplastic astroglia appear to acquire the capacity to downregulate microglial MHC class II expression and, at the same time, may induce T‐cell clonal anergy through aberrant expression of MHC class II molecules.
Identification of glial cell proliferation in early multiple sclerosis lesions
Authors: Schönrock  , Kuhlmann  , Adler  , Bitsch  , Brück
Published: March 2003

Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system which leads to destruction of myelin sheaths. The patterns of cell proliferation in the early course of the disease are largely unknown. The present study used immunohistochemical identification of proliferating glial cells in stereotactic brain biopsy material of eight patients with early chronic MS. Double‐labelling with the proliferation marker MIB‐1 detected proliferating oligodendrocytes (MOG), astrocytes (GFAP) and microglia/macrophages (Ki‐M1P). The majority of proliferating cells were macrophages/microglia when compared with oligodendrocytes (P>0.005) or astrocytes (P>0.0005); only a minor proportion of microglia/macrophages, however, proliferated in situ. Astrocytic and oligodendroglial proliferation was sparse to absent and showed significant variations between different patients. There were statistically significant differences when comparing the amount of proliferation between lesions of different demyelinating activity: highest numbers of proliferating cells were found in early active lesions compared with demyelinated and early remyelinated lesions (P>0.05) or the periplaque white matter (P>0.01). MOG‐positive oligodendrocytes proliferated occasionally in the early stages of lesion formation; this proliferation occurred in four cases but was independent of the stage of the disease. Since MOG is expressed by mature oligodendrocytes, and not by immature precursors, this might suggest a potential role for the proliferation of mature surviving oligodendrocytes with subsequent remyelination.
DNA breaks detected by in situ end‐labelling in dorsal root ganglia of patients with AIDS
Authors: Adle‐Biassette  , Bell  , Creange  , Sazdovitch  , Authier  , Gray  , Hauw  , Gherardi
Published: March 2003

Distal sensory axonal polyneuropathy (DSP) is the most frequent HIV‐associated peripheral neuropathy. DSPs tend to occur in full‐blown AIDS and worsen as CD4 cell counts decrease in blood. To assess a possible role for apoptosis in the pathogenesis of the neuropathy, we used in situ end‐labelling (ISEL) detecting DNA strand breaks in DRG neurons of 19 HIV‐infected patients, of whom nine had axonal polyneuropathy, and 11 controls. Sensory neurons with ISEL‐assessed DNA breaks were observed in 9/19 patients with AIDS, 0/3 patients with pre‐AIDS, and 1/11 controls. The prevalence of DNA breaks in neurons was higher in AIDS patients than in controls (P<0.05). Among AIDS patients, DNA breaks in neurons were more abundant in patients with peripheral neuropathy (P<0.04). It is possible that DNA breaks of DRG neurons induce the axonopathy and consequently play a role in the pathogenesis of DSP. It cannot be excluded, however, that DNA breaks could represent the result rather than the cause of axonopathy. We suggest that ISEL may detect neurons that were primed to apoptosis before death in relation with the HIV infection, and undergo DNA fragmentation at time of death, rather than neurons that underwent pre‐mortem both priming and triggering steps of the apoptotic process. This hypothesis could explain why most ISEL‐positive neurons lack typical apoptotic morphology and why normal controls do not show ISEL positive cells.
Cervical lymph nodes play the role of regional lymph nodes in brain tumour immunity in rats
Authors: Okamoto  , Yamashita  , Hasegawa  , Fujisawa  , Yamashima  , Hashimoto  , Nonomura  , Matsumoto  , Kida
Published: March 2003

Recent physiological and anatomical studies have demonstrated that a major fraction of brain interstitial and cerebrospinal fluid drains into cervical lymph nodes (CLN) in a number of experimental animals. To investigate the role of CLN in brain tumour immunity, temporal profiles of MHC class II molecule expression and T lymphocyte subsets in brain tumours, CLN and other lymphoid tissues were analysed by immunocytochemistry. A total of 64 Wistar rats weighing 250 g were used. Two weeks after the transplantation of C6 glioma cells (106 cells/1 μl) into a rat brain, expression of MHC class II molecules was induced in the brain and all systemic lymphoid tissues examined. However, the subsequent appearance of CD4 or CD8 positive cells was strictly confined to CLN, and coincided with the infiltration of such cells into the brain tumour 2 weeks after transplantation. In the group of animals in which cervical lymphadenectomy was followed by intracerebral transplantation of C6 glioma cells, infiltration of CD4 or CD8 positive cells into the brain tumour was delayed until 3 weeks after the transplantation, and the production of such cells was by the spleen. These results suggest that CLN act as regional lymph nodes in brain tumour immunity.
Low amyloid (Aβ) plaque load and relative predominance of diffuse plaques distinguish argyrophilic grain disease from Alzheimer’s disease
Authors: Tolnay  , Calhoun  , Pham  , Egensperger  , Probst
Published: March 2003

Argyrophilic grain disease constitutes one cause of late‐onset dementia. Its classification among dementia disorders is still unclear because most of the reported argyrophilic grain disease cases are associated with neurofibrillary lesions (e.g. neurofibrillary tangles) which are also typical of Alzheimer’s disease. In the present study we determine whether argyrophilic grain disease is associated with the senile plaques of Alzheimer’s disease. The distribution and density of senile plaques was systematically investigated in 11 demented argyrophilic grain disease cases using Aβ immunohistochemistry and stereological techniques, and the results were compared with 11 Alzheimer’s disease cases. All subjects with argyrophilic grain disease exhibited neurofibrillary changes corresponding to Braak stages I–III. Three of the 11 argyrophilic grain disease cases (27%) were completely devoid of Aβ deposits. In argyrophilic grain disease cases with senile plaques, the average total plaque‐load was significantly lower (1%) than in Alzheimer’s disease (3.1%) (P<0.005). The regional distribution of the senile plaques and the proportion of diffuse vs. primitive or mature plaques in argyrophilic grain disease resembled values of senile plaques reported in non‐demented elderly subjects, and was significantly different from Alzheimer’s disease. Similarly the immunocytochemical profile of the Aβ deposition in argyrophilic grain disease resembled that of non‐demented elderly subjects rather than that of subjects with Alzheimer’s disease. As all argyrophilic grain disease cases under investigation were demented, including those devoid of senile plaques, the present study further supports the thesis that dementia in argyrophilic grain disease correlates more with the density and distribution of argyrophilic grains than with associated lesions of the Alzheimer‐type.
Cocaine induces cell death within the primate fetal cerebral wall
Authors: He  , Song  , Lidow
Published: March 2003

Transferase dUTP nick‐end labelling (TUNEL) analysis was used to compare the occurrence of cell death in the cerebral wall of cocaine‐exposed and drug‐naïve monkey fetuses. The rhesus monkeys providing the drug‐exposed fetuses received 10 mg/kg of cocaine orally (in fruit treats) in the morning and in the evening between pregnancy days 50 and 65. The control pregnant animals received fruit treats only. The fetuses were removed for analysis by Caesarean section 10 h after the last cocaine treatment. The sections of the cerebral wall from the cocaine‐exposed fetuses contained significantly higher numbers of TUNEL‐positive nuclei (counted either per section area or per 1000 unlabeled nuclei) than the matching sections from the drug‐naïve fetuses. This elevation in the number of TUNEL‐positive cells was observed through the entire depth of the fetal cerebral wall including its proliferative and intermediate zones, cortical plate and the marginal zone. The present study demonstrates that consumption of cocaine during pregnancy can result in increased occurrence of cell death in the developing cerebrum.
3‐Nitropropionic acid induces a spectrum of Huntington’s disease‐like neuropathology in rat striatum
Authors: Vis  , Verbeek  , De Waal  , Ten Donkelaar  , Kremer
Published: March 2003

Systemic administration of the mitochondrial toxin 3‐nitropropionic acid (3‐NP) to rats results in selective striatal lesions and serves as an experimental model of Huntington’s disease (HD). However, the effects of the 3‐NP treatment are unpredictable and result in lesions of variable severity. The present study was aimed at further characterizing the variability of the striatal lesions induced by systemic administration of 3‐NP using osmotic pumps. Hematoxylin–eosin (HE) and Nissl stains as well as immunohistochemical labelling of astrocytes and striatal neurones were performed to analyse the neurotoxic effects of 3‐NP. In general, chronic systemic administration of 3‐NP resulted in obvious bilateral striatal lesions, which ranged from mild to severe, together with a subtle, but detectable behavioural lesion. Severe type lesions showed marked neuronal loss and an increased expression of glial fibrillary acidic protein (GFAP) in astrocytes surrounding the lesion area, whereas in the core of the lesion GFAP‐immunoreactivity was absent. The mild type lesion was characterized by a substantial loss of striatal neurones and an increased expression of GFAP‐positive astrocytes throughout the lesion. In a number of 3‐NP‐treated animals, neither type of lesion was observed, although these animals demonstrated behavioural changes in the paw test compared to controls. In the striatum of these tested 3‐NP‐treated animals, compromised rk’ neurones were detected, suggestive of subtle and early 3‐NP‐induced neuronal injury. Similar dark neurones were also detected in mild and severe lesions and were immunocytochemically characterized as γ‐aminobutyric acid (GABA) and substance P containing spiny neurones, which belong to the neuronal population that is affected in early HD. These results indicate that systemic administration of 3‐NP to rats may result in a spectrum of striatal pathology of which the morphology of the mild type lesion resembles the characteristic HD neuropathology most closely.
Prion protein immunoreactivity in brain samples from an unselected autopsy population: findings in 200 consecutive cases
Authors: Esiri M. M. , Carter J. , Ironside J. W.
Published: March 2003

Immunostaining for prion protein (PrP) using the KG9 monoclonal antibody was undertaken on brain sections from an unselected group of 200 post‐mortem cases. One case of clinically diagnosed vCJD was confirmed and showed widespread abundant PrP immunostaining with KG9 and somewhat less abundant PrP with another monoclonal antibody, 3F4. PrP immunostaining seen with KG9 was insensitive to proteinase K pretreatment in sections from this case of vCJD. Among the remaining 199 cases, sections from 84 (42%) showed small amounts of PrP immunoreactivity with the KG9 antibody, mainly localized to neurones, neural processes and argyrophilic plaques of the type seen in ageing and Alzheimer's disease. Purkinje cells, swollen (ischaemic) axons, macrophages and microglials cells were also occasionally labelled with this antibody in non‐CJD cases. Pre‐treatment of adjacent sections from non‐CJD cases with positive KG9 staining abolished this staining, indicating that it represented the cellular form of PrP. There were differences in age, sex and cause of death in non‐CJD cases with some PrP immunostaining patterns compared with cases lacking any staining. Specifically, a younger mean age, more females and fewer cardiac deaths were found among those with neuronal PrP staining patterns. Staining of some features was also significantly associated. These findings need to be taken into account when PrP immunostaining is used to diagnose prion diseases. They may indicate that cellular PrP is increased in the human brain under some circumstances and provide insight into the handling of this protein by human brain cells.
Influence of different fixation procedures on the quantification of infarction and oedema in a rat model of stroke
Authors: Overgaard K. , Meden P.
Published: March 2003

In pharmacodynamic studies using focal ischaemia models, the size of the infarct measured by quantitative histology is the most important outcome measure. Precise, unbiased and reproducible assessment of infarct volume is of foremost importance. A frequent problem in interventional stroke models is the evaluation of infarcts in animals found dead, where instant post‐mortem fixation of the brain cannot be performed. The purpose of this study was to investigate possible bias from perfusion, immediate and 3‐h post‐mortem delayed immersion fixation on the measured volumes of cerebral infarction, oedema and hemispheres in a rat embolic stroke model. Thirty‐six male Sprague–Dawley rats were thromboembolized into the internal carotid artery. After survival for 24 h, the animals were divided into three groups: group 1 – immediate perfusion fixation; group 2 – immediate immersion fixation of the brain; and group 3 – animals left dead for 3 h at room temperature before removal of the brain for immersion fixation. Following histological preparation and evaluation, the volumes of the hemispheres and infarction were measured by quantitative histology and planimetry. Brains fixed by immersion were 7% larger than the perfusion‐fixed brains. Delaying the immersion fixation for 3 h may increase hemisphere volume by a further 12%. Independent of the fixation procedure, the size of infarction was ∼40% of the ipsilateral hemisphere, and the oedema was ∼11% of the size of the infarct. The used planimetric technique was accurate with measured values within ± 2% of the factual value. In conclusion, sizes of hemispheres, infarction and oedema in absolute volume measures are influenced by the effect of unwanted variation of brain size caused by biological factors and artificial shrinkage caused by fixation, dehydration and heat treatment of the specimens. Infarction and oedema expressed relatively in per cent of hemisphere and infarct, respectively, are robust measures independent of the investigated fixation procedures.
Ageing of substantia nigra in humans:  cell loss may be compensated by hypertrophy
Authors: Cabello C. R. , Thune J. J. , Pakkenberg H. , Pakkenberg B.
Published: March 2003

In a stereological study of the human substantia nigra (SN), the total number of melanin‐positive and melanin‐negative neurones from 28 male subjects aged 19–92 years was estimated using a uniform sampling design and optical disectors. There was a significant decrease in the total number of melanin‐positive neurones as a function of age (r2=0.18, residual‐CV=0.35, 2P=0.032). Using the rotator method, the size distribution of the melanin‐positive neurones was estimated and showed a significant difference in mean cell volume of melanin‐positive neurones between the seven youngest (21 077 µm3) and the seven oldest individuals (32 011 µm3), 2P=0.022. Using a combination of the total number of melanin‐positive neurones and their size distribution, the total perikaryon volume of melanin‐positive neurones could be estimated and showed no decrease with increasing age (r2=0.01, residual‐CV=0.41, 2P=0.62).

Age‐related decline in dopamine‐transporter neurones within the SN might explain the occurrence of extrapyramidal symptoms in many elderly individuals. Although age‐related cell hypertrophy is usually considered to be an indication of cell degeneration or necrosis, this might not always be the case. The fact that motor symptoms, although present in many of the elderly, are of a limited nature despite the high percentage of lost neurones could be due to a compensatory increase in the cell body of dopamine‐producing SN neurones. Thus, the total amount of cell substance capable of producing the essential transmitters might not be reduced to a critically low level as a result of ageing.
OLIG‐1 and 2 gene expression and oligodendroglial tumours
Authors: Hoang‐Xuan K. , Aguirre‐Cruz L. , Mokhtari K. , Marie Y. , Sanson M.
Published: March 2003

OLIG 1/2 genes encode basic helix‐loop‐helix transcription factors that play a critical role in motor neurone and oligodendrocyte fate specification during development. Two recent studies in which OLIG transcripts were detected by in situ hybridization have reported a high expression of the OLIG genes in oligodendrogliomas. This suggests that the detection of these lineage markers could become an adjunct to the classic morphological diagnosis of these tumours. There are problems in the diagnosis of oligodendroglioma. To date, all other known oligodendrocyte lineage markers have failed to label specifically neoplastic oligodendrocytes. Deletions on chromosome 1p and 19q are much more frequent in oligodendrogliomas than in astrocytomas but these molecular alterations are not constant. For the future, when routinely available, immunohistochemical techniques using anti‐OLIG antibodies on paraffin embedded tissues will allow a systematic study of a large series of tumours so that we will know the specificity and sensitivity of this investigation in diagnosis.

At another level, it is possible that expression of OLIG in neoplastic oligodendrocyte might participate in the oncogenesis of oligodendrogliomas. Initial work suggests that this is probably not the case. However further in vitro and in vivo studies analysing the functional consequence of OLIG overexpression in terms of proliferation and tumour progression are needed.
Brain biopsy in Creutzfeldt–Jakob disease: evolution of pathological changes by prion protein immunohistochemistry
Authors: Mahadevan A. , Shankar S. K. , Yasha T. C. , Santosh V. , Sarkar C. , Desai A. P. , Satishchandra P.
Published: March 2003

The formation of protease‐resistant prion protein (PrPsc) is considered to be an early event in the pathogenesis of Creutzfeldt–Jakob disease (CJD) and hence its demonstration in brain biopsies by immunohistochemistry is considered diagnostic. We analysed eight brain biopsies from the frontal cortex collected from different parts of India from cases diagnosed as CJD on clinical and pathological grounds for the expression of prion protein (PrP). The duration of illness in these cases varied from 2 months to 1 year. Immunohistochemistry was carried out on paraffin sections using two different clones (KG9 and 3F4) of monoclonal antibodies to PrP. Although all eight cases showed classical features of spongiform encephalopathy of varying severity, only five of the eight cases revealed PrPsc in the brain tissue. The immunolabelling was focal and all areas with spongiform change were not labelled. A temporal evolution in the staining pattern was evident – particulate diffuse labelling (synaptic type) in early stages (2 months), perivacuolar deposits in intermediate stages (5–6 months), and dense plaques in late stages (12 months).