bluuebunny/crossref_metadata_2025 huggingface dataset:
Critical role of the N‐terminal residues of listeriolysin O in phagosomal escape and virulence of Listeria monocytogenes
Authors: Lety Marie‐Annick , Frehel Claude , Berche Patrick , Charbit Alain
Published: March 2003

A putative PEST sequence was recently identified close to the N‐terminus of listeriolysin O (LLO), a major virulence factor secreted by the pathogenic Listeria monocytogenes. The deletion of this motif did not affect the secretion and haemolytic activity of LLO, but abolished bacterial virulence. Here, we first tested whether the replacement of the PEST motif of LLO by two different sequences, with either a very high or no PEST score, would affect phagosomal escape, protein stability and, ultimately, the virulence of L. monocytogenes. Then, we constructed LLO mutants with an intact PEST sequence but carrying mutations on either side, or on both sides, of the PEST motif. The properties of these mutants prompted us to construct three LLO mutants carrying single amino acid substitutions in the distal portion of the PEST region (P49A, K50A and P52A; preprotein numbering). Our data demonstrate that the susceptibility of LLO to intracellular proteolytic degradation is not related to the presence of a high PEST score sequence and that the insertion of two residues immediately downstream of the intact PEST sequence is sufficient to impair phagosomal escape and abolish bacterial virulence. Furthermore, we show that single amino acid substitutions in the distal portion of the PEST motif are sufficient to attenuate bacterial ­virulence significantly, unravelling the critical role of this region of LLO in the pathogenesis of L. ­monocytogenes.
Evolution of signalling in the sporulation phosphorelay
Authors: Stephenson Keith , Hoch James A.
Published: March 2003

Two‐component and phosphorelay signal transduction systems are believed to function as environ‐mental sensors that programme gene expression to the composition of the ecological niche in which a microbe normally resides. The question of how evolutionarily related bacteria that occupy different environments change their signal transduction pathways to adapt to such environments was asked of the sporulation phosphorelay of Bacillus subtilis, Bacillus halodurans, Bacillus anthracis and Bacillus stearothermophilus. Comparison of the primary amino acid sequence of phosphorelay proteins with the known structural and interactive properties of the B. subtilis proteins revealed that the amino acid residues of interaction surfaces between phosphorelay proteins and between a phosphorelay protein and DNA resist evolutionary change. The absolute conservation of interaction surfaces allowed the identification of sporulation sensor kinases in B. halodurans, B. anthracis and B. stearothermophilus. In these sensor kinases, the signal‐sensing domains are vastly different in size and subdomain composition, with little apparent conservation between species, whereas the catalytic domains of these sensor kinases retain the high level of homology observed for the other phosphorelay proteins. Adaptation to new environments appears to result in rapid evolution of signalling domains to maximize environmental impact while maintaining identical protein–protein and protein–DNA contacts in the entire phosphorelay. In Clostridial genomes, only the Spo0A protein was found, suggesting that the anaerobic relatives of the Bacilli do not use a phosphorelay and phosphorylate Spo0A directly with sensor kinases.
Conjugative transposons: the tip of the iceberg
Authors: Burrus Vincent , Pavlovic Guillaume , Decaris Bernard , Guédon Gérard
Published: March 2003

Elements that excise and integrate, such as prophages, and transfer by conjugation, such as plasmids, have been found in various bacteria. These elements appear to have a diversified set of characteristics including cell‐to‐cell contact using pili or cell aggregation, transfer of single‐stranded or double‐stranded DNA, low or high specificity of integration and serine or tyrosine recombinases. This has led to a highly heterogeneous nomenclature, including conjugative transposons, integrative ‘plasmids’, genomic islands and numerous unclassified elements. However, all these elements excise by site‐specific recombination, transfer the resulting circular form by conjugation and integrate by recombination between a specific site of this circular form and a site in the genome of their host. Whereas replication of the circular form probably occurs during conjugation, this replication is not involved in the maintenance of the element. In this review, we show that these elements share very similar characteristics and, therefore, we propose to classify them as integrative and conjugative elements (ICEs). These elements evolve by acquisition or exchanges of modules with various transferable elements including at least ICEs and plasmids. The ICEs are probably widespread among the bacteria.
Primary and secondary metabolism, and post‐translational protein modifications, as portrayed by proteomic analysis of Streptomyces coelicolor
Authors: Hesketh A. R. , Chandra G. , Shaw A. D. , Rowland J. J. , Kell D. B. , Bibb M. J. , Chater K. F.
Published: March 2003

The newly sequenced genome of Streptomyces coelicolor is estimated to encode 7825 theoretical proteins. We have mapped approximately 10% of the theoretical proteome experimentally using two‐dimensional gel electrophoresis and matrix‐assisted laser desorption ionization time‐of‐flight (MALDI‐TOF) mass spectrometry. Products from 770 different genes were identified, and the types of proteins represented are discussed in terms of their anno‐tated functional classes. An average of 1.2 proteins per gene was observed, indicating extensive post‐translational regulation. Examples of modification by N‐acetylation, adenylylation and proteolytic processing were characterized using mass spectrometry. Proteins from both primary and certain secondary metabolic pathways are strongly represented on the map, and a number of these enzymes were identified at more than one two‐dimensional gel location. Post‐translational modification mechanisms may therefore play a significant role in the regulation of these pathways. Unexpectedly, one of the enzymes for synthesis of the actinorhodin polyketide antibiotic appears to be located outside the cytoplasmic compartment, within the cell wall matrix. Of 20 gene clusters encoding enzymes characteristic of secondary metabolism, eight are represented on the proteome map, including three that specify the production of novel metabolites. This information will be valuable in the characterization of the new metabolites.
A novel repressor of nif and glnA expression in the methanogenic archaeon Methanococcus maripaludis
Authors: Lie Thomas J. , Leigh John A.
Published: March 2003

Nitrogen assimilation in the methanogenic archaeon Methanococcus maripaludis is regulated by transcriptional repression involving a palindromic ‘nitrogen operator’ repressor binding sequence. Here we report the isolation of the nitrogen repressor, NrpR, from M. maripaludis using DNA affinity purification. Deletion of the nrpR gene resulted in loss of nitrogen operator binding activity in cell extracts and loss of repression of nif (nitrogen‐fixation) and glnA (glutamine synthetase) gene expression in vivo. Genetic complementation of the nrpR mutation restored all functions. NrpR contained a putative N‐terminal winged helix–turn–helix motif followed by two mutually homologous domains of unknown function. Comparison of the migration of NrpR in gel‐filtration chromatography with its subunit molecular weight (60 kDa) suggested that NrpR was a tetramer. Several lines of evidence suggested that the level of NrpR itself is not regulated, and the binding affinity of NrpR to the nitrogen operator is controlled by an unknown mechanism. Homologues of NrpR were found only in certain species in the kingdom Euryarchaeota. Full length homologues were found in Methanocaldococcus jannaschii and Methanothermobacter thermoautotrophicus, and homologues lacking one or more of the three polypeptide domains were found in Archaeoglobus fulgidus, Methanopyrus kandleri, Methanosarcina acetivorans, and Methanosarcina mazei. NrpR represents a new family of regulators unique to the Euryarchaeota.
A conserved sequence at the C‐terminus of MinD is required for binding to the membrane and targeting MinC to the septum
Authors: Hu Zonglin , Lutkenhaus Joe
Published: March 2003

MinD is a key component of an oscillatory system that spatially regulates cell division in Escherichia coli. It is a peripheral membrane ATPase that recruits MinC and oscillates between the two halves of the cell in a MinE dependent manner. In vitro MinD binds to phospholipid vesicles in an ATP‐dependent manner and is released through MinE‐stimulated ATP hydrolysis. In this study we examined the function of the conserved C‐terminus of MinD. Short truncations of three and ten amino acids dramatically decreased the ability of MinD to localize to the membrane and spatially regulate division. These truncations bound MinC but were deficient in targeting MinC to the septum. In vitro they dimerized, but were deficient in binding to phospholipid vesicles and undergoing MinE stimulation. We suggest a model in which the ATP‐dependent dimerization of MinD affects the conformation of the C‐terminal region, a potential amphipathic helix, triggering membrane binding.
AREA directly mediates nitrogen regulation of gibberellin biosynthesis in Gibberella fujikuroi, but its activity is not affected by NMR
Authors: Mihlan Martina , Homann Veronika , Liu Ta‐Wei D. , Tudzynski Bettina
Published: March 2003

AREA (NIT2) is a general transcription factor involved in derepression of numerous genes responsible for nitrogen utilization in Gibberella fujikuroi and many other fungi. We have previously shown that the deletion of areA‐GF resulted in mutants with significantly reduced gibberellin (GA) production. Here we demonstrate that the expression level of six of the seven GA biosynthesis genes is drastically reduced in mutants lacking areA. Furthermore, we show that, despite the fact that GAs are nitrogen‐free diterpenoid compounds, which are not obviously involved in nitrogen metabolism, AREA binds directly to the promoters of the six N‐regulated genes. The binding of AREA was analysed in more detail using the promoter of one of the GA‐biosynthesis genes encoding the ent‐kaurene oxidase (P450‐4). Deletion/mutation analysis of the P450‐4 promoter fused to the Escherichia coli uidA gene, which encodes β‐glucuronidase, allowed the in vivo identification of functional GATA motifs. We have also analysed the nmr gene of G. fujikuroi (nmr‐GF) which has high similarity to the Neurospora crassa nmr‐1 and Aspergillus nidulans nmrA genes, both involved in nitrogen metabolite repression. In contrast to our expectation, deletion of nmr‐GF did not result in significant derepression of the GA biosynthesis genes in the presence of ammonium, glutamine or glutamate. Overexpression of the nmr‐GF gene fused to the strong promoter of the G. fujikuroi glutamine synthetase (gs) gene revealed only a very slight repression of the nitrate reductase (niaD) gene, resulting in weak resistance to chlorate. Surprisingly, this effect was only observed in the presence of high amounts of glutamate; cultivation on ammonium failed to induce any resistance to chlorate. Despite the limited effect of gene replacement and overexpression of nmr‐GF on the nitrogen metabolism of G. fujikuroi itself, the gene fully restored nitrogen metabolite repression in A. nidulans and N. crassa nmr mutants. Therefore, we postulate that, in contrast to A. nidulans and N. crassa, NMR does not function independently as the main modulator of AREA in G. fujikuroi.
Acyl‐homoserine lactone acylase from Ralstonia strain XJ12B represents a novel and potent class of quorum‐quenching enzymes
Authors: Lin Yi‐Han , Xu Jin‐Ling , Hu Jiangyong , Wang Lian‐Hui , Ong Say Leong , Leadbetter Jared Renton , Zhang Lian‐Hui
Published: March 2003

N
‐acylhomoserine lactones (AHLs) are used as signal molecules by many quorum‐sensing Proteobacteria. Diverse plant and animal pathogens use AHLs to regulate infection and virulence functions. These signals are subject to biological inactivation by AHL‐lactonases and AHL‐acylases. Previously, little was known about the molecular details underlying the latter mechanism. An AHL signal‐inactivating bacterium, identified as a
Ralstonia
sp., was isolated from a mixed‐species biofilm. The signal inactivation encoding gene from this organism, which we call
aiiD
, was cloned and successfully expressed in
Escherichia coli
and inactivated three AHLs tested. The predicted 794‐amino‐acid polypeptide was most similar to the aculeacin A acylase (AAC) from
Actinoplanes utahensis
and also shared significant similarities with cephalosporin acylases and other N‐terminal (Ntn) hydrolases. However, the most similar homologues of AiiD are deduced proteins of undemonstrated function from available
Ralstonia
,
Deinococcus
and
Pseudomonas
genomes. LC‐MS analyses demonstrated that AiiD hydrolyses the AHL amide, releasing homoserine lactone and the corresponding fatty acid. Expression of AiiD in
Pseudomonas aeruginosa PAO1 quenched quorum sensing by this bacterium, decreasing its ability to swarm, produce elastase and pyocyanin and to paralyse nematodes. Thus, AHL‐acylases have fundamental implications and hold biotechnological promise in quenching quorum sensing.
Regulation of the central glycolytic genes in Bacillus subtilis: binding of the repressor CggR to its single DNA target sequence is modulated by fructose‐1,6‐bisphosphate
Authors: Doan Thierry , Aymerich Stéphane
Published: March 2003

Glycolysis is one of the best and widely conserved general metabolic pathways. Bacillus subtilis enzymes catalysing the central part of glycolysis, gathering the steps of interconversion of the triose phosphates from dihydroxyacetone‐phosphate to phosphoenolpyruvate, are encoded by five genes, gapA, pgk, tpi, pgm and eno. They are transcribed in a hexacistronic operon together with cggR, the first cistron, encoding the repressor of this gapA operon. Using deletion analysis, we have localized the CggR operator between the promoter and the first gene of the operon. CggR was purified and used in gel mobility shift assays and DNase I footprinting experiments to delimit its target sequence. Site‐directed mutagenesis and in vivo tests demonstrated that it consists of two direct‐repeats (CGGGACN6TGTCN4CGGGACN6TG TC). Sequence analysis and transcriptome comparison of a wild‐type and a cggR mutant strain strongly suggested that CggR regulates only the gapA operon. The presence of glycolytic carbon sources induces expression of the gapA operon. Genetic experiments allowed us to identify the metabolic steps required for the formation of the CggR effector. In vitro experiments with the suggested candidates allowed us to demonstrate that fructose‐1,6‐biphosphate (FBP) acts as an inhibitor of CggR DNA‐binding activity (10 mM for full inhibition). FBP is thus the major signal for both CcpA‐dependent catabolite repression (or activation) and activation of the central glycolytic genes. Genomic sequence comparisons suggest that these results can apply to numerous low‐G+C, Gram‐positive bacterial species.
IL‐1β and IL‐10 have dual effects on enteric glial cell proliferation
Authors: Rühl A. , Franzke S. , Stremmel W.
Published: March 2003

Inflammatory bowel disease is typically accompanied by functional and structural changes of the enteric nervous system. In pathological studies, cellular loss and axonal degeneration have been described in the myenteric plexus. However, more recent studies suggest that the proliferation rate of myenteric glial cells is enhanced in animal models of intestinal inflammation. Therefore, we have investigated the effect of different cytokines on the proliferative response of enteric glial cells (EGCs), comparing transformed enteric glial cell lines, primary astrocyte cultures and transformed oligodendrocytes. Cells were incubated in serum‐free chemically defined medium in the presence or absence of either interleukin (IL)‐1β or IL‐10 at concentrations ranging between 0.1 and 100 ng mL–1 for 48 h. Subsequently, [3H]thymidine was added to each culture dish for an additional 6 h, and the amount of incorporated [3H] was assessed. IL‐1β significantly and dose‐dependently suppressed [3H]‐uptake by EGCs. In contrast, IL‐10 induced a biphasic response; IL‐10 at low concentrations (0.1 ng mL–1) caused a significant suppression of [3H]‐uptake, whereas high concentrations (5–100 ng mL–1) significantly enhanced [3H] uptake. These results indicate that EGC proliferation can be modulated by cytokines. The differential effects of IL‐1β and IL‐10 suggest that during intestinal inflammation there may be a regulatory interplay between different classes of cytokines modulating EGC proliferation.
Oesophageal pressure–cross‐sectional area distributions and secondary peristalsis in relation to subclassification of systemic sclerosis
Authors: Villadsen G. E. , Storkholm J. , Zachariae H. , Hendel L. , Bendtsen F. , Gregersen H.
Published: March 2003

The aim of the present study was to correlate the severity of oesophageal motor dysfunction with the severity of cutaneous disease in systemic sclerosis (SS). Patients were divided into three groups based on the degree of skin involvement: type I, acrosclerosis distal to the wrist; type II, scleroderma extending above the wrist in proximal direction; type III, diffuse cutaneous systemic sclerosis. Impedance planimetry employing distensions with pressures up to 5 kPa with the concomitant measurement of oesophageal cross‐sectional area (CSA) was used in combination with standard oesophageal manometry. Measurements were made at 7 and 15 cm above the lower oesophageal sphincter (LOS). Thirty patients (16 type I, six type II and eight type III patients) and 23 normal controls were included. LOS pressure was lower in SS patients than in normal patients, with the lowest values in type III. The CSAs were higher in SS patients than in controls at both sites (P < 0.001). The CSAs at the distal site were highest in type III, as compared to type I and II (P < 0.03). The CSA at the highest induced pressure (5.0 kPa) was 613 ± 45, 719 ± 79, and 808 ± 115 mm2 in types I, II and III, respectively. No differences in CSA were found at the proximal site between the three types of SS. The distensibility did not differ between SS and normal patients at the distal site. The distensibility was lowest in SS patients (P < 0.001) at the proximal distension site. The distensibility did not vary with the type of SS at either site. Significant differences in contraction frequency of the secondary peristalsis as function of wall tension were demonstrated between the SS patients and controls at the distal site (P < 0.05). No differences were found at the proximal site. The contraction frequency and amplitude at the distal and proximal sites did not differ among the three types. In conclusion for most parameters studied, SS patients differed from normal patients. Among SS types, the most pronounced changes were found in type III.
ATP‐gated ion channel P2X3 is increased in human inflammatory bowel disease
Authors: Yiangou Y. , Facer P. , Baecker P. A. , Ford A. P. , Knowles C. H. , Chan C. L. H. , Williams N. S. , Anand P.
Published: March 2003

P2X3 is a novel ATP‐gated cation channel that is selectively expressed by small‐diameter sensory neurones in rodents, and may play a role in nociception by binding ATP released from damaged or inflamed tissues. We have studied, for the first time, P2X3 immunoreactivity in human inflammatory bowel disease, using Western blotting and immunohistochemistry. A major 66‐kDa specific protein was found by Western blotting in all colon extracts. In the inflamed group there was a significant two‐fold increase in the relative optical density of the 66‐kDa band (21.2 ± 3.1; n=8) compared to controls (11.4 ± 3.7; n=8; P=0.009). In the control colon, P2X3‐immunoreactive neurones were scattered throughout the myenteric and submucosal plexuses, with some neurones showing immunopositive axons/dendrites. The pattern of immunostaining was similar to the neuronal marker peripherin. In general, the intensity of the staining was greater in myenteric than submucosal neurones. The number of P2X3‐immunoreactive neurones was significantly increased in the myenteric plexus of inflamed colon compared to controls (n=13; P=0.01). In humans, unlike rodents, P2X3 is thus not restricted to sensory neurones. Increased P2X3 in inflamed intestine suggests a potential role in dysmotility and pain, for which it represents a new therapeutic target.
Enteric nerve stimulation evokes a premature colonic migrating motor complex in mouse
Authors: Spencer N. J. , Bywater R. A.
Published: March 2003

Abstract The effects of enteric nerve stimuli were investigated on spontaneously occurring colonic migrating motor complexes (CMMCs) in isolated mouse colon. Changes in circular smooth muscle tension were recorded simultaneously from the proximal, mid and distal regions of an in vitro preparation of whole mouse colon at 36 ± 1 °C. The CMMCs were recorded from all preparations with a mean interval between contractions ranging from 135.2 ± 9.3 to 163.3 ± 22.4 s. The CMMCs migrated spontaneously from the proximal to distal colon and were abolished by tetrodotoxin (1 μmol L−1). In approximately half of all trials (57 of 103, n = 31), trains of stimuli (20 Hz, 2–5 s, 1 ms, 40–70 V) delivered to the mid or distal regions of colon, during the intervals between CMMCs, elicited a premature CMMC. However, similar trains of stimuli delivered to the proximal colon were without similar effects (33 trials, n = 13). It is suggested that in isolated whole mouse colon, CMMCs can be evoked prematurely by trains of electrical stimuli applied to the enteric nerves. The observation that nerve stimuli failed to evoke a premature CMMC from the proximal colon suggests that selective activation of functional ascending pathways may be required to initiate a premature CMMC.
Degeneration of the cerebellar granule cell layer in transgenic mice expressing genes of human foamy virus
Authors: Lampe  , Marino  , Rethwilm  , Aguzzi
Published: March 2003

J. Lampe, S. Marino, A. Rethwilm and A. Aguzzi (1998) Neuropathology and Applied Neurobiology24, 36–43

Degeneration of the cerebellar granule cell layer in transgenic mice expressing genes of human foamy virus

Transgenic mice expressing various combinations of structural and regulatory genes of human foamy virus (HFV) develop a neurodegenerative syndrome. Δgpe transgenic mice (which express the auxiliary bel‐1 and bet genes along with truncated forms of gag, pol, and env) develop a severe neurological syndrome consisting mainly of spastic tetraparesis and blindness, and show neuronal loss in the hippocampus and cerebral cortex. In addition, mice in two of eight Δgpe lines developed an ataxic gait. Here we studied the phenotype of these two lines, and show that these mice exhibit progressive degeneration of their cerebellar granule cells beginning at 4–8 weeks of age. Transgenic mRNA and HFV proteins accumulate in cerebellar granule cells immediately before the onset of degeneration. The Purkinje cell layer is largely unaffected by this pathological process. Probably due to the loss of granule cell processes, the cerebellar molecular layer is narrowed in the late stages of the disease. These findings indicate that HFV gene products can be neurotoxic for cerebellar granule cells.
Expression of brain‐derived neurotrophic factor protein in activated microglia of human immunodeficiency virus type 1 encephalitis
Authors: Soontornniyomkij  , Wang  , Pittman  , Wiley  , Achim
Published: March 2003

The role of neurotrophic factors and their therapeutic potential have been investigated in various neurodegenerative disorders. In neurodegeneration associated with human immunodeficiency virus (HIV) infection, neuronal function and survival may be affected by abnormal neurotrophic regulation involving HIV‐infected microglia and reactive astrocytes. To characterize the cellular localization of brain‐derived neurotrophic factor (BDNF) and its high‐affinity tyrosine kinase receptor, trkB, proteins in HIV‐1 encephalitis, we examined post‐mortem brains from patients with acquired immunodeficiency syndrome and brains from non‐HIV‐infected controls. Using double immunofluorescent confocal microscopy, we found that BDNF immunoreactivity was distributed in neocortical neuronal perikarya and neuritic processes, while in the striatum only neurites were BDNF‐immunoreactive. Additionally, the striatum with HIV infection was characterized by BDNF immunoreactivity in infiltrating activated microglia/macrophages and multinucleated giant cells. Catalytic trkB receptor immunoreactivity was observed in neuronal perikarya in the neocortex and striatum, as well as in reactive astrocytes within HIV‐infected regions. Our findings suggest that expression of BDNF by activated microglia in HIV‐1 encephalitis may affect neuronal survival and astroglial response through corresponding trkB receptors.
Changes in neuron size in cynomolgus macaques infected with various immunodeficiency viruses and poliovirus
Authors: Montgomery  , Wood  , Stott  , Sharp  , Luthert
Published: March 2003

gabctgChanges in neuron size in cynomolgus macaques infected with various immunodeficiency viruses and poliovirus

Human immunodeficiency virus (HIV) infection leads to clinically significant neuronal pathology, but the underlying mechanism remains unclear. Infection of rhesus macaques with the simian immunodeficiency virus SIVmac251has been shown to cause atrophy of hippocampal pyramidal cells. The aim of the current investigation was to determine whether SIVmac251and other viruses with differing abilities to cause immune suppression or encephalitis could cause neuronal atrophy in cynomolgus macaques. Animals infected with SIVmac251(n=22), HIV‐2 (n=6), SIVmac239(n=7) and poliovirus (n=10) were investigated, together with 16 controls. Hippocampal pyramidal cell diameter, averaged across the four CA subfields, was reduced by 16.6% in the SIVmac251group (P<0.0001) and by 13.3% in the HIV‐2 group (P<0.001), even though the latter virus does not generally cause immunosuppression. Conversely, SIVmac239 , which does cause immunosuppression, caused an average neuronal hypertrophy of 6.8% (P=0.033). Of possible relevance to the different behaviour of the two SIVs is that SIVmac239is lymphocyte tropic and does not infect CNS microgliain vivowhereas SIVmac251does. Animals inoculated with poliovirus into the lumbar spinal cord for polio vaccine neurovirulence testing acted as positive controls for CNS inflammation and they also showed an increase in neuronal diameter (4.1%,P=0.025). The atrophy seen with SIVmac251and HIV‐2 involved all CA subfields but the hypertrophy following SIVmac239or poliovirus infection was restricted to CA1 and CA2. These observations show a dissociation between the ability of immunodeficiency viruses to cause immune suppression and neuronal pathology and demonstrate that CNS inflammation per se may cause neuronal hypertrophy.
Trapidil‐mediated inhibition of CNS remyelination results from reduced numbers and impaired differentiation of oligodendrocytes
Authors: McKay  , Blakemore  , Franklin
Published: March 2003

In a previous study, we described the inhibitory effects of the growth factor‐antagonist, trapidil, on spontaneously occurring oligodendrocyte remyelination in the rat spinal cord following lysolecithin‐induced demyelination [30]. The objective of the present study was to further investigate the mechanisms of trapidil‐mediated impairment of remyelination and thus obtain greater insight into the steps at which growth factors may be involved in remyelination. To this end, an ultrastructural analysis of the cellular composition of lesions from control and trapidil‐treated animals was undertaken. Demyelination was created in the dorsal funiculus of 6‐week‐old female rats by the injection of 1.0 μl of 1% lysolecithin. The animals received daily intraperitoneal injections of trapidil (80 mg/kg) or saline for 21 days, beginning on the day of lesion induction. Quantitative electron microscopic examination of lesions from both groups of animals showed that trapidil‐treated lesions had reduced numbers of oligodendrocytes (P=0.02) with a higher relative proportion of immature phenotypes, but increased numbers of microglia (P=0.0009) and dystrophic axons (P0.02). In addition, the numbers of myelin lamellae around remyelinated axons were fewer in trapidil‐treated animals. These results suggest that trapidil‐mediated impairment of CNS remyelination is due to a blockage of growth factor‐mediated proliferation and/or recruitment of remyelinating cells. Furthermore, the presence of oligodendrocytes with a more immature phenotype and the decreased thickness of the myelin sheaths of remyelination in the trapidil‐treated animals indicate an impairment of growth factor‐mediated differentiation.
Spinal cord axonal loss in multiple sclerosis: a post‐mortem study
Authors: Ganter  , Prince  , Esiri
Published: March 2003

There is increasing interest in the contribution that axonal damage may make to clinical disability in multiple sclerosis (MS). The present study reports a post‐mortem examination of the area occupied by the lateral white matter columns of the spinal cord and nerve fibre density in the corticospinal tracts at C3 and T2 in 23 males and 20 females with MS, who lacked plaques at these levels, and in 31 controls who, although most had had some neurological disease, showed no sign of cervical or spinal cord thoracic disease. The lateral column cross‐sectional area, measured by low power image analysis of the outlined lateral columns, was reduced in MS by 17% at C3 and 21% at T2 in males and by 13% at C3 and 18% at T2 in females. These reductions were significant at both levels in males (P<0.004 at C3 and P<0.009 at T2 ) but only at T2 in females (P<0.03). The nerve fibre density, measured by automatic image analysis of ×200 microscopic fields in the region occupied by the crossed pyramidal tracts, was reduced by 41% at C3 and 42% at T2 in males and by 19% at both C3 and T2 in females. These reductions were likewise significant at both levels in males (P<0.003 and P<0.000 at C3 and T2 , respectively) and T2 only in females (P<0.045). In MS, nerve fibre density was significantly lower at C3 (P<0.004) and T2 (P<0.000) in males than females. No differences were seen in these parameters between males and females in controls. The reductions in total nerve fibre densities were entirely accounted for by reductions in small nerve fibres (cross sectional area less than 5 μm2 ). No significant reductions were seen in large fibre (cross sectional area 5 μm2 or more) densities. It is concluded that substantial axonal loss and spinal cord lateral column white matter atrophy occur at C3 and T2 in MS, and that these changes can be detected in some patients from early in the course of the disease.
Emerging and re‐emerging epidemic encephalitis: a tale of two viruses
Authors: Wong K. T.
Published: March 2003

Two major epidemics of viral encephalitis occurred in Asia in 1997 and 1998. The first was a re‐emergence of neurovirulent strains of enterovirus 71, which caused severe encephalomyelitis in children in Malaysia, Taiwan and Japan, on a background of hand, foot and mouth disease. Necropsy studies of patients who died of enterovirus 71 infection showed severe perivascular cuffing, parenchymal inflammation and neuronophagia in the spinal cord, brainstem and diencephalon, and in focal areas in the cerebellum and cerebrum. Although no viral inclusions were detected, immunohistochemistry showed viral antigen in the neuronal cytoplasm. Inflammation was often more extensive than neuronal infection, suggesting that other factors, in addition to direct viral cytolysis, may be involved in tissue damage. The second epidemic of viral encephalitis was the result of a novel paramyxovirus called Nipah, which mainly involved pig handlers in Malaysia and Singapore. Pathological evidence suggested that the endothelium of small blood vessels in the central nervous system was particularly susceptible to infection. This led to disseminated endothelial damage and syncytium formation, vasculitis, thrombosis, ischaemia and microinfarction. However, there was also evidence of neuronal infection by the virus and this may also have contributed to the neurological dysfunction in Nipah encephalitis. Some patients who seemed to recover from the acute symptoms have been re‐admitted with clinical findings suggestive of relapsing encephalitis. As these two epidemics indicate, the emergence and re‐emergence of viral encephalitides continue to pose considerable challenges to the neuropathologist, in establishing the diagnosis and unravelling the pathogenesis of the neurological disease.
Connective tissue growth factor is expressed by a subset of reactive astrocytes in human cerebral infarction
Authors: Schwab J. M. , Postler E. , Nguyen T. D. , Mittelbronn M. , Meyermann R. , Schluesener H. J.
Published: March 2003

Connective tissue growth factor (CTGF), a transforming growth factor (TGF)‐β1 downstream mediator, is a secreted cell matrix‐inducing peptide involved in both tissue regeneration mechanisms, such as wound repair, and also in aberrant deposition of extracellular matrix. The present study reports CTGF expression by cells associated with matrix deposition and glial scar formation in human cerebral infarction. CTGF was localized by immunohistochemistry in 17 brains of patients after focal infarction and in three neuropathologically normal control brains. CTGF expression was selectively localized to the cytoplasm of stellate reactive astrocytes. Compared to peripheral areas and brain controls without neuropathological findings, the total number CTGF+ astrocytes was significantly higher (P < 0.0001) in border zones adjacent to the core, corresponding to the penumbra. These numbers were significantly increased at day 1 and day 3 and remained persistently elevated up to several months post‐infarction (P < 0.0001). The restricted expression and accumulation of CTGF+ reactive astrocytes adds convincing evidence for CTGF participation in the gliotic astrocyte CNS injury response involved in glial scar formation. CTGF can be considered a sensitive marker of early human astrocyte activation and a possible target for pharmacological intervention of aberrant matrix deposition.
Genetic association of argyrophilic grain disease with polymorphisms in alpha‐2 macroglobulin and low‐density lipoprotein receptor‐related protein genes
Authors: Ghebremedhin E. , Schultz C. , Thal D. R. , Del Tredici K. , Rueb U. , Braak H.
Published: March 2003

Argyrophilic grain disease (AGD) is a neurodegenerative disorder of the aged human brain associated with the formation of abnormal tau protein in specific neurones and macroglial cells. Previously, we reported the association between AGD and the ε2 allele of apolipoprotein E (ApoE). Here, the polymorphisms of the alpha‐2 macroglobulin gene (A2M) and those of the low‐density lipoprotein receptor‐related protein gene (LRP) were assessed in 115 AGD cases and compared with 170 controls. The results reveal an association between AGD and the C766T polymorphism of LRP (P=0.001). In addition, the present study shows that the valine to isoleucine (Val1000Ile) polymorphism of A2M is linked with AGD (P=0.03). By comparison, no relationship between AGD and the intronic 5‐bp deletion/insertion polymorphism of A2M is demonstrable (P=0.8). Finally, this report corroborates and extends our earlier finding in that the frequency of the ε2 allele of ApoE is higher in AGD cases than in controls (17.4% vs. 8.5%, P=0.003), whereas the ε4 allele frequency approximates that in control cases (13.9% vs. 13.2%, P=0.93). This association, however, is only apparent in the presence of the LRP CC genotype. In conclusion, the present study shows that AGD is associated with the LRP, A2M and ApoE genes.
Peripheral nerve regeneration in galactosaemic rats
Authors: King R. H. M. , Muddle J. R. , Nourallah M. , Wong J. , Workman J. M. , Thomas P. K.
Published: March 2003

The use of galactosaemia as a model for some aspects of diabetic polyneuropathy allows the influence of glycation to be studied independently of other effects. There are well‐studied abnormalities of the peripheral nerves in galactosaemic rats, one of which is that the efficiency of regeneration is initially reduced. One possible cause could be that glycated myelin debris in macrophages is less degradable and interferes with macrophage function. Macrophage recognition and ingestion of myelin glycosylated in vitro increases with the duration of incubation in a sugar‐rich medium. This study was performed to investigate a possible correlation between galactosaemia and regeneration, together with the role of macrophages. Galactosaemia was induced by adding galactose to the rats’ diet for 2 months before injury. Following a crush lesion to the sciatic nerve, regeneration was found to be delayed, demonstrated by a reduction in mean myelinated fibre size and density 1 month after crush, although, 2 and 3 months later, the differences did not reach statistical significance. There were also more macrophages in the galactosaemic rats than in the control animals at all time points. The initial delay in regeneration in galactosaemic rats was therefore only temporary and there was little evidence of long‐term deleterious effects. In addition to the morphometric results, immunohistochemistry showed that there were more macrophages in the galactosaemic rats than in the control animals at all time points. Correlating macrophage and myelinated fibre counts suggests that the persistence of debris‐containing macrophages does not appear to have a significant inhibitory effect on nerve regeneration. No evidence was found for persistent basal laminal tubes around the regenerating clusters.
Evidence for an ischaemic origin of deep white matter lesions in the ageing brain
Authors: Ince P. G. , Fernando M. ,   on behalf of the MRC Cognitive Function and Ageing Neuropathology Study
Published: March 2003

Introduction:  The pathogenesis of white matter lesions (WMLs) is not established. Evidence from clinical,. pathological and pathophysiological studies favours a vascular mechanism for subcortical WMLs (DWML) and a nonischaemic origin for periventricular (PV) hyperintensities. Small vessel degeneration giving rise to ischaemia is the hypothetical origin for subcortical WMLs.

Methods:  PV lesions (PVL) and deep subcortical lesions (DWML) demonstrated in MRI scans of fixed coronal brain slices, from elderly postmortem brain donors to the MRC CFAS(N) cohort, were sampled together with nonlesional WM from the same brains. Immunohistochemistry was performed to detect activated microglia (CD68), endothelial activation (ICAM‐1), capillary basement membrane (Collagen IV), and hypoxia‐inducible factor‐1α (HIF‐1α) expression. Quantitative analysis of microvasculature was performed with digital images using Image Pro Plus software. The sample consisted of 18 PV (seven nonlesional) and 23 DWML (11 nonlesional) regions from 15 subjects. Statistical analysis was performed using SPSS software.

Results:  Vascular changes in arterioles were related to ML and not to dementia. DWML arterioles had thicker walls (P < 0.001; 95%CI = 5.6–8.4), bigger external diameters (P < 0.001; 95%CI = 7.7–17.8) and larger perivascular spaces (P < 0.05; 95%CI = 13.3–19.4) than nonlesional areas. Vascular lumen diameters remained the same. The ICAM‐1/Collagen 4 ratio was significantly elevated in lesional DWML (P = 0.001) but not in the periventricular regions (P = 0.85) reflecting capillary endothelial activation. HIF‐1α expression (P = 0.004) and presence of activated microglia (P = 0.001) were more frequent in DWML. The prevalence (χ2 = 0.053; P = 0.82) and absolute counts (P = 0.07) of HIF‐1α expression, and the presence of activated microglia (P = 0.95) in PVL were not increased over control WM.

Discussion:  DWML show vascular degenerative changes in arterioles, reactive changes in capillaries and persistent HIF expression, all consistent with chronic ischaemia. The study raises the possibility that an age‐related impairment of the neovascular response to ischaemia results in WM lesions.
‘Back to sleep’: the position in Oxfordshire and Northampton
Authors: Rose Mandy , Murphy Mike , Macfarlane Aidan J. , Sefi Sue , Shribman Sheila , Hales Vee
Published: March 2003

We examined hospital and domestic infant care practices in Oxfordshire and Northampton Health Districts to measure changes in prevalence of sudden infant death syndrome (SIDS) risk factors, and to evaluate a specific educational intervention restricted to Oxfordshire. We sent a postal questionnaire to 2781 parents of babies newly born in January 1992, July 1992 and January 1993 and achieved an 88% response rate. Overall, in hospital a relatively constant proportion (81%) slept on their sides and few prone, whereas at home 52% (but increasing) slept supine and 8% prone part or all of the time. Significant differences existed by district, both in hospital and at home, with more sleeping supine in Oxfordshire and more side‐sleeping/propping in Northampton. First‐time parents were more receptive to safety guidelines about sleeping position and several other risk factors also. We detected no modifying effect of the Oxfordshire advice. Professional practice can influence parental behaviour but general media coverage may produce the biggest effects.
Evidence for an association between environmental tobacco smoke exposure and birthweight: a meta‐analysis and new data
Authors: Windham  , Eaton  , Hopkin
Published: March 2003

Because of the strong association of active smoking with fetal growth retardation, increasing interest has focused on whether there is also an association with exposure to environmental tobacco smoke (ETS). We examined this issue in a retrospective study and by conducting a review of the literature and data pooling. In our study, nonsmoking women with singleton livebirths born in 1986–87 (n = 992) provided information on exposure to ETS for 1 h or more per day and paternal smoking. The risk of low birthweight (LBW, < 2500 g) was not increased in infants of ETS‐exposed women, but there was a somewhat increased risk for LBW at term (adjusted odds ratio [OR] 1.8, 95% confidence interval [CI] 0.6, 4.8) and small‐for‐gestational‐age (< 10th percentile of weight; OR = 1.4, 95% CI = 0.8, 2.5). These results were in the range of 16 other studies in the literature that had odds ratios from 1.0 to 2.2. A weighted average of the results of all studies on LBW at term or small‐for‐gestational‐age yielded a pooled estimate of 1.2 [95% CI = 1.1, 1.3] in nonsmoking women. The pooled estimate of mean birthweight indicated a decrement of 28 g with ETS exposure of nonsmoking women [95% CI = −41, −16], with a greater decrement (about 40 g) seen among more homogeneous studies.
Repeated neonatal deaths in families with special reference to causes of death
Authors: Alam  , Van Ginneken
Published: March 2003

It is recognized that one infant death in a family indicates an increased risk of death of a subsequent sibling. This study examines which cause of death of a sibling is related to the mortality of the younger sibling and when. Longitudinal vital events data from the maternal and child health and family planning (MCH‐FP) project and the comparison areas in Matlab, Bangladesh, were used. Primary causes of 868 neonatal deaths and 624 post‐neonatal deaths resulting from 18 865 singleton live births in 1989–92 and those (967 as neonates and 708 as post‐neonates) of their immediate elder siblings were categorised into infectious and non‐infectious diseases. Multinomial logistic regression was used to estimate the risk of younger siblings dying in each age period from infectious and non‐infectious diseases given the age and cause of deaths of older siblings and controlling for other biosocial correlates of infant mortality. A neonatal death of non‐infectious causes in a family was twice as likely to be followed by another one occurring at the same age from similar causes compared with a surviving infant followed by a neonatal death from non‐infectious causes. The MCH‐FP project, though successful in reducing the risk of neonatal and post‐neonatal mortality from infectious diseases, did not reduce the risk of dying from non‐infectious diseases.
Maternal height and prepregnancy body mass index as risk factors for selected congenital anomalies
Authors: Shaw G.M. , Todoroff K. , Schaffer D.M. , Selvin S.
Published: March 2003

Previous studies have observed an increased risk of approximately twofold or more for neural tube defects (NTD) associated with maternal obesity before pregnancy based on a body mass index (BMI) of > 29 kg/m2. No additional maternal factor appeared substantially to influence this association. Here, we explore further the association between BMI and NTD risk by considering the separate contributions of maternal prepregnant BMI and height. We also explore whether selected congenital anomalies, in addition to NTDs, were associated with maternal height or prepregnant BMI. Data were derived from two California population‐based case–control studies. One study comprised 538 NTD cases and 539 non‐malformed control infants. The other study included an additional 265 NTD cases, as well as 207 conotruncal cases, 165 limb anomaly cases, 662 orofacial cleft cases and 734 non‐malformed controls. Maternal interviews in both studies elicited information on maternal height and prepregnant weight. Anomaly risk was described using additive linear logistic regression models. Results revealed increasing NTD risk with increasing maternal prepregnant BMI, controlling for maternal height. These patterns were observed overall as well as for most race/ethnic groups. Increasing NTD risk for decreasing height controlling for maternal BMI was also observed in one NTD study, but was not as evident in the other. Elevated risks for increasing maternal BMI and decreasing maternal height were not observed consistently for the other studied anomalies. The mechanisms underlying the association between maternal weight, or possibly maternal height, and NTD‐affected pregnancy risk are unknown. Exploration of other data sets will be needed to determine whether similar patterns of NTD risk or lack of risk for other anomalies are associated with the two maternal anthropometric variables, height and prepregnant weight.
Preterm delivery: a public health perspective
Authors: Mattison Donald R. , Damus Karla , Fiore Ellen , Petrini Joann , Alter Caroline
Published: March 2003

And his daughter‐in‐law, the wife of Phinehas, was pregnant near to giving birth, and got to hear the report that the ark of the true God was captured and that her father‐in‐law and her husband had died. At that she bowed herself and began giving birth, because her pangs came unexpectedly upon her.