bluuebunny/crossref_metadata_2025 huggingface dataset:
AraC/XylS family members, HilD and HilC, directly activate virulence gene expression independently of HilA in Salmonella typhimurium
Authors: Akbar Samina , Schechter Lisa M. , Lostroh C. Phoebe , Lee Catherine A.
Published: March 2003

Salmonella typhimurium
is a Gram‐negative enteric pathogen that can infect intestinal epithelial cells and induce inflammation of the intestinal mucosa. These processes are mediated by a type III secretion system (TTSS), which is encoded on
Salmonella
pathogenicity island 1 (SPI1). Previous studies showed that four SPI1‐encoded transcriptional regulators, HilD, HilC, HilA and InvF, act in an ordered fashion to co‐ordinately activate expression of the SPI1 TTSS. HilD and HilC derepress
hilA
transcription. HilA activates
invF
as well as SPI1 genes that encode components of the TTS apparatus. InvF then activates genes that encode proteins secreted by the SPI1 TTS apparatus. In this scheme, HilD and HilC indirectly activate expression of the SPI1 TTS apparatus and its secreted substrates by affecting
hilA
expression. Here, we report that HilD and HilC can also activate expression of a subset of SPI1 genes independently of HilA. Our studies show that HilD and HilC activate transcription of
invF
from a promoter that is far upstream of its HilA‐dependent promoter. This activation is most probably through direct binding of HilD and HilC to sequences upstream and downstream of this alternative HilA‐independent promoter. We conclude that HilD and HilC have a second role in SPI1 gene regulation that is separate from their role in co‐ordinating expression of the SPI1 TTSS through
hilA .
SseA acts as the chaperone for the SseB component of the Salmonella Pathogenicity Island 2 translocon
Authors: Zurawski Daniel V. , Stein Murry A.
Published: March 2003

The Salmonella Pathogenicity Island 2 (SPI2) encodes a type III secretion system (TTSS) shown to be critical for adaptation to the intracellular environment within both phagocytic and epithelial cell types. Within SPI2, the Effector region encodes several exported proteins that comprise the SPI2 translocon (SseB, C, D). SseA is the first protein encoded within the Effector region but remains an unclassified factor that is essential for SPI2 function. In the present study, we determined that SseA shares several features with TTSS chaperones: it is small (12.5 kDa), located directly upstream of a TTSS export target (SseB), and contains an amphipathic, C‐terminal α‐helix. Construction and analysis of a ΔsseA mutant demonstrated that the total amount of SseB is significantly reduced and SPI2 export of SseB to the bacterial surface is prevented. SseB accumulation and export were restored when SseA was provided in trans. Loss of SseA does not cause a generalized defect in SPI2 secretory function as export of SseC, encoded downstream of SseB, still occurs in the ΔsseA strain. Quantitative PCR indicates that the loss of SseB in ΔsseA does not occur at the transcriptional level. Co‐purification studies demonstrate that SseA directly binds to SseB. Collectively, these results demonstrate that SseA functions as a TTSS chaperone for the SPI2 translocon component, SseB.
A hexA homologue from Photorhabdus regulates pathogenicity, symbiosis and phenotypic variation
Authors: Joyce Susan A. , Clarke David J.
Published: March 2003

Photorhabdus
is a genus of entomopathogenic Gram‐negative bacteria that belong to the family Enterobactericeae. Remarkably, at the same time as being pathogenic to insect larvae,
Photorhabdus
also have a mutualistic relationship with entomophagous nematodes of the family Heterorhabditiae.
Photorhabdus
can be isolated in two phenotypically distinct forms, termed the primary and secondary variant. Both variants grow equally well and are equally virulent when injected into insect larvae. However, only the primary variant can colonize the intestinal tract of the IJ stage of the nematode and support nematode growth and development. The primary variant expresses several phenotypes that are absent from the secondary variant, including the production of extracellular enzymes, pigments, antibiotics and light. In this study, we use
Photorhabdus temperata
strain K122 to show that these primary‐specific products are symbiosis factors, i.e. factors that are required for nematode growth and development. We also show that, in
P. temperata
K122, the production of these symbiosis factors is repressed in the secondary variant by the protein encoded by a gene with homology to
hexA
from
Erwinia
. Moreover, the derepression of the symbiosis factors in the secondary variant results in a significant attenuation of virulence to larvae of the greater wax moth,
Galleria mellonella . This suggests that, during a normal infection, pathogenicity and symbiosis must be temporally separated and that HexA is involved in the regulation of this pathogen–symbiont transition.
Streptococcus dysgalactiae‐derived mitogen (SDM), a novel bacterial superantigen: characterization of its biological activity and predicted tertiary structure
Authors: Miyoshi‐Akiyama Tohru , Zhao Jizi , Kato Hidehito , Kikuchi Ken , Totsuka Kyoichi , Kataoka Yasushi , Katsumi Masanori , Uchiyama Takehiko
Published: March 2003

A mitogenic substance, designated Streptococcus dysgalactiae‐derived mitogen (SDM), was purified from S. dysgalactiae culture supernatant, and the gene encoding the mitogen was cloned. Both native and recombinant SDM expressed in Escherichia coli significantly activated human Vβ1+ and Vβ23+ T cells in association with major histocompatibility complex (MHC) class II molecules on accessory cells, indicating that SDM possesses superantigenic properties. The sdm gene consists of two segments encoding a signal peptide and a mature 25 kDa protein composed of 212 amino acids. Three of 34 S. dysgalactiae strains but none of 28 Streptococcus pyogenes strains examined carried sdm. Phylogenetic analysis indicated that SDM belongs to a family distinct from established bacterial superantigens. SDM showed around 30% homology with other superantigens at the amino acid sequence level. The tertiary structure of SDM was predicted by modelling onto streptococcal pyrogenic exotoxin C and streptococcal mitogenic exotoxin Z‐2, both of which share highly homologous structure‐determining regions. SDM showed overall structural similarity to both these superantigens. This is the first study to characterize fully a bacterial superantigen from S. dysgalactiae.
Correlation of electrophysiology, neurochemistry and axonal projections of guinea‐pig sphincter of Oddi neurones
Authors: Hillsley K. , Mawe G.M.
Published: March 2003

Sphincter of Oddi (SO) ganglia are comprised of two main types of neurones based either on their electrical or neurochemical properties. This study investigated whether any correlation exists between the electrical and neurochemical properties of these cells. SO neurones were characterized electrically as either Tonic or Phasic cells, labelled with neurobiotin, fixed, and processed for β‐nicotinamide adenine dinucleotide phosphate diaphorase (NADPH‐DA) staining and choline acetyltransferase immunoreactivity to identify whether electrically characterized neurones were nitrergic or cholinergic. A total of 119 cells were analysed in this manner; 45% of cells were Tonic and 37% were Phasic. An equivalent number of Tonic (58.1%, 18/31) and Phasic cells (60%, 21/35) were choline acetyltransferase (ChAT) positive. Three of 34 Phasic cells were NADPH‐DA positive, whereas 11/33 Tonic cells were NADPH‐DA positive. In none of the preparations was ChAT immunoreactivity and NADPH‐DA reactivity ever observed in the same neurone. Calretinin immunoreactivity was present in a subpopulation of both Tonic and Phasic neurones. No correlation was observed between the direction of axon projections and the electrophysiological or neurochemical properties of the cell. These results suggest that there is a lack of correlation between the electrical properties and the neurochemical content of SO neurones. Various explanations for these findings are discussed.
Autonomic dysfunction in patients with achalasia of the oesophagus
Authors: HERBAY  , HEYER  , OLK  , KIESEWALTER  , AUER  , ENCK  , HÄUSSINGER  , FRIELING
Published: March 2003

It has been suggested that achalasia is associated with extraoesophageal sympathetic and parasympathetic dysfunction. In a prospective study we applied conventional ultrasonography and duplex sonography to investigate basal and postprandial peak systolic velocity (PSV), pulsatility index (PI) and resistance index (RI) of superior mesenteric artery and PSV of portal vein in nine patients with achalasia and 10 healthy controls (study I). In addition, in eight of these patients autonomic nervous function was investigated by pupillary function tests as well as cardiovascular reflex tests and compared with eight age‐ and sex‐matched controls (study II). The results indicated that postprandial increase of PSV in the superior mesenteric artery was significantly lower, and postprandial decrease of PI and RI significantly higher in achalasia compared to healthy controls. In contrast, postprandial increase of PSV in the portal vein was not significantly different between both groups. Autonomic function tests revealed significant lower maximal pupillary contraction and redilatation velocities, significantly lower heart rate variation during orthostasis, deep respiration test and Valsalva manoeuvre in achalasia compared to controls. It is concluded that achalasia is associated with extraoesophageal autonomic nervous dysfunction that involves cardiovascular and pupillary function as well as regulation of mesenteric arterial blood flow.
Serotonin stimulates migrating myoelectric complex via 5‐HT3‐receptors dependent on cholinergic pathways in rat small intestine
Authors: LÖRDAL  , HELLSTRÖM
Published: March 2003

We have investigated the effect of 5‐hydroxytryptamine (5‐HT) and different 5‐HT‐receptor antagonists and atropine on the migrating myoelectric complex in the rat small intestine.

Infusion of 5‐HT dose‐dependently shortened the interval between phase III of the migrating myoelectric complex (MMC). In untreated animals the interval in upper jejunum was 19.1 (16.0–22.1) min. At doses of 10 and 20 nmol kg–1 min–1, the interval decreased to 15.2 (12.0–18.4) and 10.2 (9.4–11.0) min, respectively. The 5‐HT3‐receptor antagonist ondansetron (0.5 mg kg–1) alone increased the MMC interval from 20.8 (15.1–26.5) to 33.9 (19.4–48.4) min. Neither methiothepin (0.5 mg kg–1) nor ketanserin (0.5 mg kg–1), selective for 5‐HT15‐HT2‐and 5‐HT2‐receptors, respectively, changed the MMC interval. The 5‐HT4‐receptor antagonist GR 113808 (0.5 mg kg–1) disrupted the MMC and induced irregular spiking activity.

Ondansetron and atropine antagonized the 5‐HT‐induced shortening of the MMC interval. Neither methiothepin nor ketanserin affected the response to 5‐HT. GR 113808 did not block the response to 5‐HT in half of the animals; however, in the remaining ones MMC was disrupted and irregular spiking induced.

In conclusion, these results show that 5‐HT dose‐dependently stimulates the cycling of the MMC in the small intestine via 5‐HT3‐receptors and a cholinergic final pathway. Our findings encourage further studies on the role of the 5‐HT3‐receptor in the control of gastrointestinal motility.
The effect of vesical filling and voiding on the anorectal function with evidence of a `vesico‐anorectal reflex'
Authors: SHAFIK
Published: March 2003

The aim was to evaluate the effect of vesical filling and voiding on anal continence and rectal pressure. Fourteen healthy volunteers (age 37.2 ± 9.6 years; 10 men, four women) were studied. The response of the rectal pressure and EMG of the external (EAS) and internal (IAS) anal sphincters to slow vesical filling and voiding was recorded before and after individual anaesthetization by xylocaine of the EAS, rectum and urinary bladder. Saline instead of xylocaine was used as control testing. The rectal pressure and EAS EMG activity showed no response to vesical filling (P > 0.05, P > 0.05, respectively) while a momentary increase in both parameters occurred upon voiding (P < 0.05, P < 0.01, respectively). The IAS EMG exhibited no response to either filling or voiding. Separate anaesthetization of either of the EAS, rectum or bladder produced no response of the rectal pressure or EAS EMG activity upon vesical voiding, whereas a response was registered after saline administration. The increase of the rectal pressure and EAS EMG activity upon voiding suggests the presence of a reflex relationship between the two actions. This relationship is evidenced by reproducibility and by abolition of the response on anaesthetizing either of the proposed two arms of the reflex: the anorectum and the bladder. We call this reflex `vesico‐anorectal reflex'. The clinical significance of this vesico‐anorectal reflex remains to be established.
The pharmacological properties of the novel selective 5‐HT3 receptor antagonist, alosetron, and its effects on normal and perturbed small intestinal transit in the fasted rat
Authors: CLAYTON  , SARGENT  , BUTLER  , GALE  , MAXWELL  , HUNT  , BARRETT  , CAMBRIDGE  , BOUNTRA  , HUMPHREY
Published: March 2003

The purpose of this study was to investigate the pharmacological properties of the novel, selective 5‐HT3 receptor antagonist, alosetron, and its effects on transit time in both the normal and perturbed small intestine of the rat. Alosetron concentration‐dependently inhibited radioligand binding in membranes containing rat and human 5‐HT3 receptors with estimated pKi values of 9.8 (n = 3) and 9.4 (n = 6), respectively. In selectivity studies alosetron had little or no significant affinity for any of the many other receptors and ion channels studied. Alosetron potently antagonized the depolarization produced by 5‐HT in the rat vagus nerve (estimated pKB value of 9.8, n = 25). In anaesthetized rats, i.v. administration of alosetron inhibited 2‐methyl‐5‐HT induced bradycardia (Bezold Jarisch index) at 1 and 3 μg kg–1, with an agonist dose ratio of approximately 3.0 at 1.0 μg kg–1, = 3–5). Alosetron administered via the duodenum also inhibited this reflex, with duration of action that was significantly longer than that seen with ondansetron (120–60 min, respectively, n = 6). Alosetron had no significant effect on normal small intestinal propulsion in the rat, but fully reversed the increase in intestinal propulsion (96%, n = 3) produced by egg albumin challenge. Alosetron is a highly selective 5‐HT3 antagonist which normalizes perturbed small intestinal propulsion. Previous clinical data in IBS patients together with the transit data provide a good rationale for further studies with alosetron in IBS patients.
Rectal visceral sensitivity in healthy volunteers: influences of gender, age and methods
Authors: Sloots  , Felt‐Bersma  , Cuesta  , Meuwissen
Published: March 2003

The barostat is a device that maintains a constant pressure within an air‐filled polyethylene bag by means of a feedback mechanism. The system measures variations in rectal tone by recording changes in the intrarectal pressure and volume. Different procedures, such as ramp distension or intermittent distension, are used to test visceral sensitivity and rectal wall compliance. It is not quite clear which method is preferable and how the barostat measurements compare with those of the conventional latex balloon. In 28 healthy volunteers (11 males, mean age 36, range 22–67 years) rectal distension was performed in two ways:

1  Pressure‐controlled distension, by both intermittent and ramp methods, with measurement on the Visual Analogue Scale (VAS, 0–5) at 8, 12, 16, 20, 24, 28, 32 and 36 mmHg. Hysteresis (comparing area under the curve during deflation and inflation with ramp pressure distension) and compliance were calculated.

2  Volume‐controlled distension, with registration of first sensation, urge to defecate and maximal tolerated distension. This procedure was compared to conventional water‐filled latex balloon distension.

No differences were found between intermittent and ramp distension comparing VAS scores at the same pressures. Gender or age did not affect the VAS score. Males had larger volumes at the same pressures than females. Females had larger hysteresis than males. Older females had larger hysteresis than younger females. The pressure volume curves were S‐shaped. Compliance at maximal tolerated distension (V/p) and maximal dynamic compliance (ΔV/Δp) was higher in males than females. The polyethylene bag had higher MTV and MTP compared to the latex balloon. In conclusion, no differences were found in volumes, compliance or VAS between the intermittent and the ramp pressure‐controlled inflation, indicating potential for simplification of the procedure. Males had larger rectal volumes and compliances; females had more pronounced hysteresis. A systemic difference was found between distension with the water‐filled latex balloon and with the air‐filled polyethylene bag. This should be taken into account when interpreting results.
Isolation of enteric glia and establishment of transformed enteroglial cell lines from the myenteric plexus of adult rat
Authors: Rühl A. , Trotter J. , Stremmel W.
Published: March 2003

Although enteroglial cells (EGCs) may play a key role in the inflammatory response of the enteric nervous system, little is known about their immunophysiological properties. To facilitate further characterization of enteric glia, we have developed a novel method to isolate and purify EGCs from the myenteric plexus. Myenteric plexus preparations were enzymatically dissociated and EGCs purified by complement‐mediated cytolysis of contaminating cells and transformed by retroviral gene transfer. Primary and transformed cells were characterized immunohistochemically and by dot‐blot analysis. Functionally, c‐fos mRNA expression was assessed in primary and transformed enteroglial cells. All cells displayed robust glial fibrillary acidic protein, S‐100 and vimentin immunoreactivities, but no Thy‐1.1, desmin, smooth muscle α‐actin or C3 complement receptor immunoreactivity. This confirmed their enteroglial lineage and excluded contamination with other cell types. Both primary and transformed EGCs displayed little constitutive c‐fos mRNA expression. This, however, could be upregulated by various stimuli, including proinflammatory cytokines. In summary, we present a novel method to purify EGCs from rat myenteric plexus for tissue culture and to establish transformed EGC lines that retain their glial nature and functional properties. Such cell lines are now available for physiological studies of the functional properties of enteric glia in vitro.
Oesophageal morphometry and residual strain in a mouse model of osteogenesis imperfecta
Authors: Gregersen H. , Weis S. M. , Mcculloch A. D.
Published: March 2003

Recently, it was demonstrated in the oesophagus that the zero‐stress state is not a closed cylinder but an open circular cylindrical sector. The closed cylinder with no external loads applied is called the no‐load state and residual strain is the difference in strain between the no‐load state and the zero‐stress state. To understand the physiology and pathology of the oesophagus, it is necessary to know the zero‐stress state and the stress–strain relationships of the tissues in the oesophagus, and the changes of these states and relationships due to biological remodelling of the tissues under stress. The aim of this study was to investigate the morphological and biomechanical remodelling at the no‐load and zero‐stress states in mutant osteogenesis imperfecta murine (oim) mice with collagen deficiency. The oesophagi of seven oim and seven normal wild‐type mice were excised, cleaned, and sectioned into rings in an organ bath containing calcium‐free Krebs solution with dextran and EGTA. The rings were photographed in the no‐load state and cut radially to obtain the zero‐stress state. Equilibrium was awaited for 30 min and the specimens were photographed again. Circumferences, submucosa and muscle layer thicknesses and areas, and the opening angle were measured from the digitized images. The oesophagi in oim mice had smaller layer thicknesses and areas compared to the wild types. The largest reduction in layer thickness in oim mice was found in the submucosa (approximately 36%). Oim mice had significantly larger opening angles (120.2 ± 4.5°) than wild‐type mice (93.0 ± 11.2°). The residual strain was compressive at the mucosal surface and tensile at the serosal surface in both oim and wild types. In the oim mice, the residual strains at the serosal and mucosal surfaces and the mucosa‐submucosal–muscle layer interface were higher than in the wild types (P < 0.05). The gradient of residual strain per unit thickness was higher in oim mice than in wild‐type mice, and was highest in submucosa (P < 0.05). The only morphometric measure that was similar in oim and wild‐type mice was the inner circumference in the no‐load state. In conclusion, our data show significant differences in the residual strain distribution and morphometry between oim mice and wild‐type mice. The data suggest that the residual stress in oesophagus is caused by the tension in the muscle layer rather than the stiffness of the submucosa in compression and that the remodelling process in the oim oesophagus is due mainly to morphometric and biomechanical alterations in the submucosa.
Structural and mechanical remodelling of the common bile duct after obstruction
Authors: DUCH B. U. , ANDERSEN H. L. , SMITH J. , KASSAB G. S. , GREGERSEN H
Published: March 2003

Biliary obstruction in man, most often caused by cholelithiasis, induces remodelling of the bile ducts. Obstruction‐induced structural remodelling of the common bile duct (CBD) has been previously described. The mechanical changes that accompany the structural remodelling, however, have not been studied in detail. The aim of this study is to quantify the structural and mechanical changes in the CBD at different time intervals after acute obstruction. The CBD was ligated in the pig, near the duodenum, and studied after 3 h, 12 h, 2 days, 8 days and 32 days (n=5 in each group). One additional animal in each group was sham‐operated. At each scheduled time, the CBD was mechanically tested in vitro with a computer‐controlled volume infusion system to study the pressure–volume relationship of the CBD segment. A video camera provided simultaneous measurements of the outer dimensions of the CBD at the various pressures. The diameter and wall thickness of the CBD increased about three‐fold in the 32‐day group compared to the sham group (P < 0.001). The circumferential stress–strain relationship differed between groups (P < 0.001); it was shifted to the right, indicating softening, in the 3‐h, 12‐h, and 2‐day groups and to the left, indicating stiffening, in the 8‐day and 32‐day group, compared to the sham group. The longitudinal stress–strain curves were all shifted to the left of the circumferential stress–strain curves (P < 0.05). The collagen area increased during obstruction (P < 0.001) but no correlation between the size of the collagen area and the biomechanical parameters was found. A practical implication of the present study serves as a warning to surgeons. A reduction in the wall stiffness in the first several days of obstruction along with an increased duct diameter and a decreased wall thickness suggest that operative procedures such as suturing, anastomosis and procedures related to ERCP must be performed with special care to avoid damage to the CBD.
Effects of pramlintide, an amylin analogue, on gastric emptying in type 1 and 2 diabetes mellitus
Authors: VELLA A. , LEE J. S. , CAMILLERI M. , SZARKA L. A. , BURTON D. D. , ZINSMEISTER A. R. , RIZZA R. A. , KLEIN P. D.
Published: March 2003

Pramlintide delays gastric emptying, possibly by a centrally mediated mechanism. Our aim was to determine whether the effects of pramlintide on gastric emptying differ in people with type 1 or type 2 diabetes who had no history of complications. Using a randomized, three‐period, two‐dose, crossover design, we studied the effects of 0, 30, or 60 μg t.i.d. pramlintide subcutaneously for 5 days each in six type 1 and six type 2 diabetic subjects. Gastric emptying of solids was measured by 13C‐Spirulina breath test. Plasma pancreatic polypeptide (HPP) response to the test meal was also measured. Relative to placebo [t 50% 91 ± 6 min (means ± SEM)], pramlintide equally delayed gastric emptying following 30 or 60 μg t.i.d. (268 ± 37 min, 329 ± 49 min, respectively; P < 0.01]. Postprandial HPP levels were lower in response to 30 and 60 μg pramlintide compared to placebo. There were no significant differences in the effects on gastric emptying or HPP levels between type 1 and type 2 diabetic subjects. Pramlintide delays gastric emptying in diabetes unassociated with clinically detected complications. Further studies are needed in diabetic patients with impaired gastric motor function.
Lower oesophageal sphincter relaxation evoked by stimulation of the dorsal motor nucleus of the vagus in ferrets
Authors: Abrahams T. P. , Partosoedarso E. R. , Hornby P. J.
Published: March 2003

Abstract
 
An understanding of the neural control of lower oesophageal sphincter (LOS) relaxation is clinically relevant because transient LOS relaxations (TLOSRs) are a mechanism of acid reflux into the oesophagus. Preganglionic motor neurones innervating the LOS are localized in the dorsal motor nucleus of the vagus (DMV). Based on a single study in cats, it is now widely accepted that these neurones are functionally organized into two separate populations, such that stimulation of the caudal and rostral DMV evokes LOS relaxation and contraction, respectively. Our goal was to map the functional LOS responses to chemical stimulation in the DMV and nucleus tractus solitarius (NTS) of ferrets, an animal model commonly used for conscious studies on TLOSRs, and to test whether DMV‐evoked LOS relaxation is mediated through hexamethonium‐sensitive vagal‐inhibitory pathways to the LOS. We used miniaturized manometry with Dentsleeve to monitor LOS and oesophageal pressures in decerebrate unanaesthetized ferrets. LOS relaxation was evoked readily in response to gastric insufflation, which shows that the vago–vagal reflex was intact in this preparation. Microinjections of l‐glutamate (12.5 nmol L−1in 25 nL) were made into the DMV from approximately − 1.5 to + 2.0 mm relative to the obex. Microinjections into the caudal (− 1.5 to + 0.0 mm behind obex) and intermediate (+ 0.1 to + 1.0 mm rostral to obex) DMV both significantly decreased LOS pressure, and complete LOS relaxation was noted in 28/32 and 11/18 cases, respectively. LOS relaxation responses to DMV microinjection were highly reproducible and abolished by bilateral vagotomy or hexamethonium (15 mg kg−1intravenously). A nitric oxide synthase inhibitor (l‐NAME 100 mg kg−1intramuscularly) significantly increased the time taken to reach the maximal response. Increases in LOS pressure (24 ± 4 mmHg; n = 3) were obtained only when stimulation sites were located equal to greater than 1.5 mm rostral to the obex. LOS relaxation (− 78 ± 10%; n = 6) was evoked by stimulation of the NTS but not immediately outside of the NTS (11 ± 27%; n = 5). We conclude that there is a very extensive population of ‘inhibitory’ motor neurones in the DMV that may account for the predominant vagal‐inhibitory tone in ferrets. As NTS stimulation evokes LOS relaxation and the predominant response to DMV stimulation is also LOS relaxation, this vago–vagal reflex may involve an excitatory interneurone between the NTS and DMV vagal inhibitory output.
Relationship between colonic motility and cholinergic mechanosensory afferent synaptic input to mouse superior mesenteric ganglion
Authors: Miller S. M. , Szurszewski J. H.
Published: March 2003

Abstract
 Abdominal prevertebral ganglion neurones receive excitatory synaptic input from intestinofugal neurones. To better understand the physiological significance of this input, we examined the relationship between synaptic input to mouse superior mesenteric ganglion (SMG) neurones and intracolonic pressure and volume changes that accompany spontaneous colonic contractions in vitro. Electrical activity was recorded intracellularly from SMG neurones in ganglia attached to a segment of distal colon. The majority of neurones examined received ongoing fast excitatory potentials (F‐EPSPs). F‐EPSP frequency increased when the colon was distended with fluid and during spontaneous increases in colonic volume that accompanied colonic relaxation. In contrast, F‐EPSP frequency in SMG neurones decreased when the colon emptied, and remained at a reduced frequency until the colon refilled and volume increased. Nicotinic blockade of the colon abolished spontaneous colonic contractions and reduced or abolished synaptic input to SMG neurones, suggesting that most of the synaptic input arose from second or higher order neurones. Retrograde labelling identified cell bodies of intestinofugal neurones in myenteric ganglia. Most had short, club‐like dendritic processes and appeared uni‐axonal. These results show that mechanosensory intestinofugal afferent nerves monitor intracolonic volume changes.
SCN5A is expressed in human jejunal circular smooth muscle cells
Authors: Ou Y. , Gibbons S. J. , Miller S. M. , Strege P. R. , Rich A. , Distad M. A. , Ackerman M. J. , Rae J. L. , Szurszewski J. H. , Farrugia G.
Published: March 2003

Abstract
 Tetrodotoxin‐resistant Na+currents are expressed in a variety of muscle cells including human jejunal circular smooth muscle (HJCSM) cells. The aim of this study was to determine the molecular identity of the pore‐forming α‐subunit of the HJCSM Na+channel. Degenerate primers identified a cDNA fragment of 1.5 kb with 99% nucleotide homology with human cardiac SCN5A. The identified clone was also amplified from single smooth muscle cells by reverse transcriptase–polymerase chain reaction (RT–PCR). Northern blot analysis showed expression of full‐length SCN5A. Laser capture microdissection was used to obtain highly purified populations of HJCSM cells. RT–PCR on the harvested cells showed that SCN5A was present in circular but not in longitudinal muscle. A similar result was obtained using a pan‐Na+channel antibody. The full‐length sequence for SCN5A was obtained by combining standard polymerase chain reaction with 5′ and 3′ rapid amplification of cDNA end techniques. The intestinal SCN5A was nearly identical to the cardiac SCN5A. The data indicate that SCN5A is more widely distributed than previously thought and encodes the pore‐forming α‐subunit of the tetrodotoxin‐resistant Na+current in HJCSM cells.
Model of rapid gastrointestinal transit in dogs: effects of muscarinic antagonists and a nitric oxide synthase inhibitor
Authors: Chiba T. , Bharucha A. E. , Thomforde G. M. , Kost L. J. , Phillips S. F.
Published: March 2003

Abstract
 Our aims were to establish a canine model of rapid gastrointestinal transit, and to test the effects of muscarinic receptor antagonists (atropine, pirenzepine, AF‐DX116, and darifenacin), and an NOS inhibitor, l‐nitro‐N‐arginine (l‐NNA) in this model. For gastric emptying and small bowel transit,99mTc‐labelled DTPA were added to a meal of skimmed milk (236 mL) that contained 2.4 g of magnesium hydroxide. Regional colonic transit was measured by111In‐labelled beads placed in a capsule that released isotope in the proximal colon. Scintiscans were taken at regular intervals and indices of transit were calculated. Drugs were administrated intravenously. Gastric emptying, small bowel and colonic transit were rapid. Atropine and darifenacin (a selective M3antagonist) delayed gastric emptying and colonic transit, the selective M1and M2muscarinic antagonists did not. The muscarinic blockers did not slow small bowel transit. l‐NNA delayed small bowel and colonic transit but did not slow gastric emptying. A model suitable for the preclinical study of antidiarrhoeals was established. M3receptors are important in the control of gastric emptying and colonic transit, and NOS inhibition slowed small bowel and colonic transit.
Intraduodenal capsaicin inhibits gastric migrating motor complex via an extrinsic neural reflex in conscious dogs
Authors: Shibata C. , Naito H. , Ueno T. , Jin X.‐L. , Funayama Y. , Fukushima K. , Matsuno S. , Sasaki I.
Published: March 2003

Abstract
 The aim was to study the effect of intraduodenal capsaicin on interdigestive gastric contractions. Mongrel dogs were equipped with strain‐gauge force transducers to measure gastroduodenal motility. The effects of intraduodenal capsaicin with or without pharmacological antagonists on spontaneous and motilin‐induced interdigestive gastric contractions and on plasma motilin were studied in dogs with intact stomachs. The effect of intraduodenal capsaicin on gastric contractions was also studied in vagally denervated gastric (Heidenhain) pouch and vagally innervated antral pouch. Intraduodenal capsaicin inhibited spontaneous and motilin‐induced gastric contractions. The spontaneous peak in plasma motilin was inhibited by intraduodenal capsaicin. The effect of intraduodenal capsaicin on motilin‐induced gastric contractions was not affected by blockade of nitric oxide synthase, or by β‐adrenoceptor antagonist. Administration of α‐adrenergic blocker inhibited basal interdigestive gastric motility. Intraduodenal capsaicin had no effect on contractions in the Heidenhain pouch but inhibited those in vagally innervated antral pouch. Duodenal afferent fibres stimulated by capsaicin inhibit gastric contractions via a nitric oxide‐independent extrinsic neural reflex.
Effect of the 5‐HT1 agonist sumatriptan on oesophageal motor pattern in patients with ineffective oesophageal motility
Authors: Grossi L. , Ciccaglione A. F. , Marzio L.
Published: March 2003

Abstract The 5‐HT1 agonist sumatriptan (SUM) elicits an increase in amplitude of oesophageal motor waves and of lower oesophageal sphincter (LOS) tone in healthy subjects. The aim of the study was to evaluate whether such an effect occurs also in patients with ineffective oesophageal motility (IOM). 16 patients (nine males and seven females, age range 34–55 years) with chest pain and mild to moderate dysphagia were studied; all had undergone previous cardiologic, radiologic and upper gastrointestinal endoscopic exams that were normal. An oesophageal manometry was performed using an electronic probe to record swallows, oesophageal, LOS and gastric motility. The patients whose motor pattern were compatible with IOM (>30% of motor waves with amplitude <30 mmHg and/or non‐transmitted) received SUM or placebo 6 mg s.c., injected in the morning and in the afternoon in a random order. The data analysis was limited to 1 h before and 1 h after the drug injections. Ten out of the 16 patients showed an IOM motor pattern. The administration of SUM caused a significant increase in the number of swallows (SUM 99.5 ± 15.4 vs 78.6 ± 16.1 basal, P = 0.03) and of primary oesophageal motor waves (SUM 89.6 ± 13.4 vs 67.2 ± 12.9 basal, P = 0.04) with no significant changes in the percentage of swallows associated with propagation. Placebo was not associated with increase in the number of swallows (80.3 ± 14.6, P = 0.9) or of primary oesophageal motor waves (70.1 ± 12.3, P = 0.7). The amplitude and the percentage of propagated oesophageal motor waves as well as the mean basal LOS tone were unaltered by SUM. There was no change in the symptoms reported after SUM. Although effective in healthy subjects, SUM 6 mg s.c. improves only the numbers but not the amplitude or propagation of oesophageal motility of patients with IOM. The 5‐HT1 pathway and its acute stimulation seem to play only a minor role in the pathogenesis of such a disease.
Why do we remember Dorothy Russell?
Authors: Geddes
Published: March 2003

Dorothy Russell (1895–1983), one of the leading figures in the brief history of British neuropathology, is remembered by the Society in a biennial Memorial Lecture. So rapid is progress in the Neurosciences and so short our memories, that for a younger generation of neuropathologists she is probably no more than a name associated with a large recently revised textbook on brain tumours. However, together with Godwin Greenfield, Dorothy Russell had a profound and lasting influence on the development and practice of Neuropathology throughout the world.
Non–rabies Lyssavirus human encephalitis from fruit bats: Australian bat Lyssavirus (pteropid Lyssavirus) infection
Authors: Samaratunga  , Searle  , Hudson
Published: March 2003

A 39‐year‐old woman died of encephalitis a few weeks after being scratched by fruit bats. Autopsy disclosed meningoencephalomyelitis, and revealed neuronal intracytoplasmic inclusions which had similarities to Negri bodies of rabies. Laboratory investigations detected a Lyssavirus type previously identified only in fruit bats. This appears to be the first human case of encephalitis due to this Lyssavirus type.
Cellular localization of PDGF mRNAs in developing human forebrain
Authors: Maxwell  , Galanopoulos  , Neville‐Golden  , Hedley‐Whyte  , Antoniades
Published: March 2003

Platelet‐derived growth factor (PDGF) has been implicated in the processes regulating gliogenesis in the CNS. Conflicting in vivo data in rodents have variously implicated either glia or neurons as being the primary source of PDGF. We have used in situ hybridization and immunocytochemical analysis to study the in vivo expression and cellular localization of PDGF‐A, sis/PDGF‐B, together with the two PDGF receptors α and β, in developing human forebrain. In this study we demonstrate the strong expression of mRNA and protein of both PDGF chains, A and B, and their receptors, α and β, in human embryonic glial cells. The neurons, in contrast to glial cells, expressed lower levels of PDGF and PDGF‐receptor mRNAs and protein. Identification of the cell types expressing the PDGF and PDGF‐receptor mRNAs was achieved by counterstaining with antibodies specific for glial cells (GFAP) and neurons (NF). The predominant glial‐specific expression of both PDGF‐A and PDGF‐B, together with the coexpression of their receptors α and β, suggests an important role for the PDGF isoforms in the development of human embryonic glial cells and neurons in vivo.
Expression of angiogenic factors in rabbit spinal cord after transient ischaemia
Authors: Hayashi  , Sakurai  , Abe  , Sadahiro  , Tabayashi  , Itoyama
Published: March 2003

It is known that angiogenic factors are induced in brain by ischaemia, and new vessel formation is correlated with better prognosis in patients of stroke. However, the role of angiogenesis and expression of angiogenic factors in spinal cord ischaemia is uncertain. We here investigated expression of three highly potent angiogenic peptides, i. e. basic fibroblast growth factor (bFGF), vascular endothelial growth factor (VEGF), and hepatocyte growth factor (HGF) in the rabbit spinal cord after transient ischaemia, by Western blot and immunohistochemical analysis. Western blot analysis revealed that bFGF was induced at 8 h after transient ischaemia and decreased thereafter. Immunoreactive VEGF was also induced at 8 h, and it disappeared thereafter. HGF was not detected in the spinal cord with sham‐operation or ischaemic injury. By immunohistochemical analysis, bFGF was weakly expressed in only a few small interneurons in sham‐operated spinal cords. However, it was induced to a marked degree in motor neurons and interneurons of the anterior horn at 8 h after reperfusion. It was also induced in small neurons of the posterior horn. The expression in the anterior horn decayed thereafter though it lasted until 7 d in the posterior horn. VEGF was not expressed in sham‐operated spinal cords, but the expression was induced in large motor neurons and interneurons at 8 h with marked reduction at 1 d. In contrast, HGF was not expressed in the spinal cord with sham‐operation or ischaemic injury. These factors are known to play pivotal roles in angiogenesis, regulation of blood flow, and protection of endothelial cells. Through induction of these angiogenic peptides, protection of vascular endothelial cells and improvement of regional blood flow might be occurring in the spinal cord after ischaemia.
Progressive dendritic pathology in cynomolgus macaques infected with simian immunodeficiency virus
Authors: Montgomery  , Dean  , Taffs  , Stott  , Lantos  , Luthert
Published: March 2003

Neuronal pathology in acquired immunodeficiency syndrome (AIDS) is of interest in relation to cognitive impairment in AIDS patients and from the broader perspective of the pathogenesis of neurodegeneration. Cortical dendritic spine loss has been described in patients with AIDS and the aim of this study was to test the hypothesis that similar pathology is present in cynomolgus macaques infected with simian immunodeficiency virus (SIV). These animals develop an AIDS‐like illness, but multinucleated giant cell encephalitis is not a feature and CNS virus load is found to be very low. Four animals infected for 2.5–3 months and four infected for 2–3 years were compared with four controls. The Golgi‐Cox technique was employed to demonstrate dendritic morphology in the frontal cortex and the diameter of apical dendrites, dendritic spine density and dendritic spine lengths were measured in layer V pyramidal cells. Immunohistochemistry for microtubule‐associated protein‐2 (MAP‐2), MHC class II and glial fibrillary acidic protein (GFAP) was also performed. In infected animals there was progressive spine loss and atrophy of remaining spines with loss of MAP‐2 immunoreactivity at late time points. No parallel increase in GFAP immunostaining or MHC‐class II expression in microglial cells was seen. We conclude that progressive neuronal dendritic pathology is a feature of SIVmac251infection of cynomolgus macaques and is apparent relatively early in disease. Furthermore, dendritic abnormalities occur in the absence of either multinucleated giant cell pathology or substantial CNS virus load.
A new case of frontotemporal dementia and parkinsonism resulting from an intron 10 +3‐splice site mutation in the tau gene: clinical and pathological features
Authors: Tolnay M. , Grazia Spillantini M. , Rizzini C. , Eccles D. , Lowe J. , Ellison D.
Published: March 2003

Hereditary frontotemporal dementia and parkinsonism (FTDP) linked to chromosome 17 (FTDP‐17) constitutes a new form of tauopathy, and mutations in the tau gene have recently been reported in some affected families. This report presents clinical and neuropathological data from a member of a British family (SOT 254) with a history of dementia and movement disorder. The medical history of the affected patient, a woman aged 44 years, was reviewed, and a detailed post‐mortem examination of the brain was undertaken. A panel of well characterized phosphorylation‐dependent and independent anti‐tau antibodies was used to assess tau pathology, and inclusions were examined by electron microscopy. Neuronal loss and gliosis were widely distributed, but most severe in neocortical regions, and were associated with abundant neuronal and glial tau inclusions which consisted of a mixture of paired helical filaments (PHFs), similar to those in Alzheimer’s disease, and distinct twisted ribbon‐like filaments. Genomic DNA was obtained from post‐mortem tissue from the index patient, and blood from two unaffected members of the same family. For the index case only, sequencing of intronic sequences flanking exon 10 of the tau gene identified a G to A transition at position +3 of the splice‐donor site downstream of exon 10, identical to that reported in multiple system tauopathy with presenile dementia (MSTD). The clinical, neuropathological and genetic findings strongly suggest that SOT 254 represents a new example of FTDP‐17 resulting from a mutation in the tau gene. These results are compared with those reported for other FTDP‐17 families, i.e. for MSTD.
Possible role of the superoxide anion in the development of neuronal tolerance following ischaemic preconditioning in rats
Authors: Mori T. , Muramatsu H. , Matsui T. , Mckee A. , Asano T.
Published: March 2003

There is a large body of evidence that reactive oxygen species play a major role in the pathogenesis of ischaemic brain damage. On the other hand, it has recently been suggested that superoxide anions participate in the development of neuronal tolerance against lethal ischaemia following ischaemic preconditioning (PC). The present study aimed to examine whether or not the intravenous administration of human recombinant Cu/Zn superoxide dismutase (hr SOD) prior to PC would affect the subsequent development of neuronal tolerance. Animals were randomly assigned to the following three groups: group 1, sham PC treated with vehicle; group 2, PC treated with hr SOD and group 3, PC treated with vehicle. For PC, 10 min occlusion of the middle cerebral artery (MCA) by a modified intraluminal suture method was followed by 60 min recirculation and this procedure was successively repeated three times. The procedures were similar for sham PC except that the MCA was kept unoccluded. Just prior to PC or sham PC, a bolus of hr SOD (6 × 103 IU/2 ml/kg) was administered intravenously. Seventy‐two hours thereafter, rats were subjected to lethal ischaemia, i.e. MCA occlusion for 100 min followed by recirculation for 48 h. The infarct area and volume were assessed with the 2,3,5‐triphenyltetrazolium stain. A significant difference in the infarct volume was revealed between the sham PC/vehicle and the PC/vehicle groups (total and cortex P < 0.01; striatum P < 0.05), showing that PC induced a marked neuronal tolerance against lethal ischaemia. The infarct volume in the PC/SOD group was close to that in the sham PC/vehicle group, being significantly greater than that in the PC/vehicle group (total and cortex P < 0.01) and showing that the administration of hr SOD suppressed the development of neuronal tolerance induced by PC. In a parallel experiment, expression of 72‐kDa heat‐shock protein (hsp 72) at 72 h after PC was considerably reduced in rats treated with hr SOD compared with those treated with vehicle. These results suggest that superoxide anions intraluminally generated within cerebral microvessels participate in the development of neuronal tolerance as well as the induction of hsp 72 following PC.
Hypoglycaemia is a cause of axonal injury
Authors: Dolinak D. , Smith C. ,   D. I. Graham
Published: March 2003

Axonal injury as demonstrated immunohistochemically is increasingly being recognized at post‐mortem in patients who have been unconscious, and in some cases the cause of the coma may not be immediately apparent. Considerations include microscopical diffuse traumatic axonal injury and axonal injury associated with a range of metabolic encephalopathies. In this study, extensive neurohistological examination was undertaken in 13 patients in whom coma was attributed to hypoglycaemia and in whom neurohistological examination had revealed varying degrees of widely distributed neuronal necrosis: in five of these cases there was also evidence that the intracranial pressure had been high with internal hernation. It is concluded that a significant amount of axonal injury found in these 13 cases can be attributed to hypoglycaemia per se although the amount and distribution of the axonal damage is altered in the presence of raised intracranial pressure. However, in some cases axonal damage is seen in the absence of an elevated intracranial pressure and in one case its distribution closely mimicked that seen in microscopical diffuse traumatic axonal injury. This further demonstrates that not all axonal pathology is traumatic, and that adequate sampling and care in interpretation of Aβ‐PP staining is required in forensic practice.