Antimuscarinic antibodies in primary Sjögren's syndrome reversibly inhibit the mechanism of fluid secretion by human submandibular salivary acinar cells

OBJECTIVE

Sjögren's syndrome (SS) is an autoimmune condition affecting salivary glands, for which a clearly defined pathogenic autoantibody has yet to be identified. Autoantibodies that bind to the muscarinic M3 receptors (M3R), which regulate fluid secretion in salivary glands, have been proposed in this context. However, there are no previous data that directly show antisecretory activity. This study was undertaken to investigate and characterize the antisecretory activity of anti-M3R.

METHODS

Microfluorimetric Ca2+ imaging and patch clamp electrophysiologic techniques were used to measure the secretagogue-evoked increase in [Ca2+]i and consequent activation of Ca2+-dependent ion channels in individual mouse and human submandibular acinar cells. Together, these techniques form a sensitive bioassay that was used to determine whether IgG isolated from patients with primary SS and from control subjects has antisecretory activity.

RESULTS

IgG (2 mg/ml) from patients with primary SS reduced the carbachol-evoked increase in [Ca2+]i in both mouse and human acinar cells by approximately 50%. IgG from control subjects had no effect on the Ca2+ signal. Furthermore, the inhibitory action of primary SS patient IgG on the Ca2+ signal was acutely reversible. We repeated our observations using rabbit serum containing antibodies raised against the second extracellular loop of M3R and found an identical pattern of acutely reversible inhibition. Anti-M3R-positive serum had no effect on Ca2+-dependent ion channel activation evoked by the direct intracellular infusion of inositol 1,4,5-triphosphate.

CONCLUSION

These observations show for the first time that IgG from patients with primary SS contains autoantibodies capable of damaging saliva production and contributing to xerostomia. The unusual but not unprecedented acute reversibility of the effects of anti-M3 autoantibodies is the subject of further research.

Clinical canine spinal cord injury provides an opportunity to examine the issues in translating laboratory techniques into practical therapy

STUDY DESIGN

Review.

OBJECTIVES

To highlight the value of investigating the effects of putative therapeutic interventions in clinical spinal cord injury (SCI) in domestic dogs.

SETTING

England, UK.

METHODS

Many experimental interventions in laboratory rodents have been shown to ameliorate the functional deficits caused by SCI; the challenge now is to determine whether they can be translated into useful clinical techniques. Important differences between clinical SCI in human patients and that in laboratory rodents are in the size of the spinal cord and heterogeneity of injury severity. A further key issue is whether the statistical difference in outcome in the laboratory will translate into a useful difference in clinical outcome. Here, we stress the value of investigating the effects of putative therapies in clinical SCI in domestic dogs. The causes of injury, ability to categorise the severity and methods available to measure outcome are very similar between canine and human patients. Furthermore, postmortem tissue more rapidly becomes available from dogs because of their short lifespan than from human patients.

RESULTS

The role that investigation of canine SCI might play is illustrated by our preliminary trials on intraspinal transplantation of olfactory glial cells for severe SCI.

CONCLUSIONS

This canine translational model provides a means of 'filtering' putative treatments before human application.

Acquired idiopathic laryngeal paralysis as a prominent feature of generalised neuromuscular disease in 39 dogs

A retrospective evaluation of 17 dogs treated surgically for idiopathic acquired laryngeal paralysis demonstrated a marked variability in outcome, with many dogs continuing to exhibit weakness and exercise tolerance. In a subsequent prospective study, 22 consecutive affected dogs were tested for neurological deficits by neurological examination, electrodiagnostic evaluation, and blood analysis to measure thyroxine and thyroid-stimulating hormone and to detect any evidence of myasthenia gravis. Clinical neurological deficits and/or electrodiagnostic abnormalities were found in each case. There was limited evidence that specific neurological deficits were associated with a poor prognosis for full recovery of exercise tolerance. None of the dogs was positive for anti-acetylcholine receptor antibodies, and only three showed evidence of thyroid dysfunction.

Spinal shock--comparative aspects and clinical relevance

Spinal shock is the loss of muscle tone and segmental spinal reflexes that develops caudal to a severe spinal cord injury. Although little recognized in the veterinary literature, spinal shock occurs in animals and is important in both accurate lesion localization and case management. In this review, we consider why spinal shock occurs and discuss the subsequent physiologic alterations, including the development of reflex hyperactivity. We also discuss differences in the expression of spinal shock between species and suggest why recovery of reflexes is relatively rapid in animals compared with humans. Finally, the implications for clinicians dealing with animals in the period immediately after severe spinal injury are considered.

Effects of caffeine ingestion on rating of perceived exertion during and after exercise: a meta-analysis

The purpose of this study was to use the meta-analytic approach to examine the effects of caffeine ingestion on ratings of perceived exertion (RPE). Twenty-one studies with 109 effect sizes (ESs) met the inclusion criteria. Coding incorporated RPE scores obtained both during constant load exercise (n=89) and upon termination of exhausting exercise (n=20). In addition, when reported, the exercise performance ES was also computed (n=16). In comparison to placebo, caffeine reduced RPE during exercise by 5.6% (95% CI (confidence interval), -4.5% to -6.7%), with an equivalent RPE ES of -0.47 (95% CI, -0.35 to -0.59). These values were significantly greater (P<0.05) than RPE obtained at the end of exercise (RPE % change, 0.01%; 95% CI, -1.9 to 2.0%; RPE ES, 0.00, 95% CI, -0.17 to 0.17). In addition, caffeine improved exercise performance by 11.2% (95% CI; 4.6-17.8%). Regression analysis revealed that RPE obtained during exercise could account for approximately 29% of the variance in the improvement in exercise performance. The results demonstrate that caffeine reduces RPE during exercise and this may partly explain the subsequent ergogenic effects of caffeine on performance.

Expression of the full-length form of gp2 of equine herpesvirus 1 (EHV-1) completely restores respiratory virulence to the attenuated EHV-1 strain KyA in CBA mice

Wild-type equine herpesvirus 1 (EHV-1) strains express a large (250-kDa) glycoprotein, gp2, that is encoded by EUs4 (gene 71) located within the unique short region of the genome. DNA sequence analysis revealed that EUs4 of the pathogenic EHV-1 strain RacL11 is an open reading frame of 2,376 bp that encodes a protein of 791 amino acids. The attenuated EHV-1 vaccine strain KyA harbors an in-frame deletion of 1,242 bp from bp 222 to 1461 and expresses a truncated gp2 of 383 amino acids. To determine the relative contribution of gp2 to EHV-1 pathogenesis, we compared the course of respiratory infection of CBA mice infected with either wild-type RacL11, attenuated KyA, or a recombinant KyA that expresses the full-length gp2 protein (KyARgp2F). Mice infected with KyA lost a negligible amount of body weight (0.18% total weight loss) on day 1 postinfection and regained weight thereafter, whereas mice infected with KyARgp2F or RacL11 steadily lost weight beginning on day 1 and experienced a 20 and 18% loss in body weight, respectively, by day 3. Immunohistochemical and flow cytometric analyses revealed higher numbers of T and B lymphocytes and an extensive consolidation consisting of large numbers of Mac-1-positive cells in the lungs of animals infected with KyARgp2F compared to animals infected with KyA. RNase protection analyses revealed increased expression of numerous cytokines and chemokines, including interleukin-1beta (IL-1beta), IL-6, tumor necrosis factor alpha, macrophage inflammatory protein 1alpha (MIP-1alpha), MIP-1beta, MIP-2, interferon gamma-inducible protein, monocyte chemotactic protein 1, and T-cell activation gene 3 at 12 h postinfection with KyARgp2F. Three independent DNA array experiments confirmed these results and showed a 2- to 13-fold increase in the expression of 31 inflammatory genes at 8 and 12 h postinfection with KyARgp2F compared to infection with KyA. Taken together, the results indicate that expression of full-length gp2 is sufficient to restore full respiratory virulence to the attenuated KyA strain and raise caution concerning the inclusion of full-length gp2 in the development of EHV-1 vaccines.

The influence of step and ramp type protocols on the attainment of peak physiological responses during arm crank ergometry

The present study examined the impact of two exercise protocols on the attainment of peak physiological responses during arm crank ergometry (ACE). Fourteen physically active, although non-specifically trained male subjects completed two V.O (2) peak tests using an electrically braked arm ergometer (Lode Angio, Groningen, Netherlands). The tests consisted of a stepwise or rampwise increase in external workload. The order of tests was randomised and each test was separated by at least two days. Respiratory data were collected continuously using an on-line gas analysis system with sample time set at 30 s. Fingertip capillary blood samples ( approximately 20 microL) were collected at volitional exhaustion and at minute intervals for 7 min of passive recovery for the determination of peak whole blood lactate concentration. Time on the test (T (lim); s), peak minute power (PMP; W), and total work done (TWD; kJ) were also recorded. In addition to determining systematic bias using separate independent t-tests, the level of agreement was also examined by way of calculating the 95 % limits of agreement. Sub-maximal values of V.O (2), V.E, and HR were similar (p > 0.05) between test when the amount of external work completed was taken into consideration. There was no systematic bias (p > 0.05) for mean (+/- s) peak values of V.O (2) (3.12 [0.37] vs. 3.04 [0.38] L . min (-1)) or any other parameter between the step and ramp tests, respectively. Mean values of T (lim), PMP, and TWD were also similar (p > 0.05) between tests. However, the level of agreement for peak values of all test parameters was low. It is therefore concluded that while either test can be considered as being suitable for the purpose of eliciting V.O (2) peak and other physiological responses using ACE, they should not be used interchangeably for the purpose of assessing parameters linked to the aerobic capacity of the upper-body.

Hydroxychloroquine therapy in patients with primary Sjogren's syndrome may improve salivary gland hypofunction by inhibition of glandular cholinesterase

OBJECTIVE

To determine whether (i) cholinesterase activity is increased in the saliva of patients with primary Sjogren's syndrome (pSS), (ii) increased levels of cholinesterase of lymphocyte origin could interfere with the secretory activity of submandibular acinar cells, and (iii) hydroxychloroquine at therapeutic doses could interfere with cholinesterase activity.

METHODS

The Ellman method was used to determine the levels of salivary cholinesterase activity and the K(i) of both chloroquine and hydroxychloroquine for serum cholinesterase. The ability of lymphocyte cholinesterase to inhibit the acetylcholine (ACh)-evoked rise in [Ca(2+)](i) in mouse submandibular acinar cells was determined using fura-2 microfluorimetry.

RESULTS

Patients with pSS had significantly higher levels of cholinesterase activity in both their unstimulated (P < 0.05) and stimulated saliva (P < 0.0001) compared with control subjects. Lymphocyte cholinesterase was capable of inhibiting the ACh-evoked rise in [Ca(2+)](i). The in vitro K(i) for hydroxychloroquine inhibition of cholinesterase was 0.38 +/- 1.4 microM.

CONCLUSION

These data suggest that increased levels of cholinesterase present in the salivary glands of patients with pSS may contribute to glandular hypofunction and provide evidence that the therapeutic enhancement of salivary secretion in patients with pSS by hydroxychloroquine may be mediated by inhibition of glandular cholinesterase activity, although further in vivo investigation is needed.

Effects of the rotor pedalling system on the performance of trained cyclists during incremental and constant-load cycle-ergometer tests

The aim of this study was to determine the effects of Rotor, a new cycle crank configuration that effectively allows the pedals to move independently throughout the duty cycle, on indices of endurance cycling performance in trained cyclists. Ten cyclists (5 Rotor users and 5 non-users; age (mean +/- SD): 22 +/- 5 y; VO(2)max: 69.5 +/- 5.1 mL. kg(-1).min(-1)) volunteered to participate in the study. On four separate days, the subjects performed four cycle-ergometer tests, i.e. two incremental tests and two 20-min tests. An imposed crank rate of 75 rev.min(-1) was used during all tests. The incremental protocol started at 112.5 W, and the power output was increased by 37.5 W every 3 min until volitional exhaustion. The 20-min tests were performed at a fixed power output equivalent to 80 % of the highest power output that the cyclists maintained for a complete 3-min period during incremental tests. Both types of tests were performed with the conventional crank system and the Rotor following a counter-balanced, cross-over design. Gas exchange parameters were measured in all the tests and blood lactate was determined at the end of each 3-min period (incremental tests) and at the end of the 20-min tests. A three factor (pedalling system used during the tests x habitual pedalling system x power output [incremental tests] or time [20-min tests]) ANOVA with repeated measures on power output (incremental tests) or time (20-min tests) was used to analyse several indices of performance, e.g. peak power output, VO(2)max, lactate threshold, onset of blood lactate accumulation, economy, delta, and gross efficiency. No differences (p > 0.05) were found between the Rotor and conventional systems for any of the aforementioned variables. It seems that the theoretical advantage brought about by the Rotor system, i.e. improved contra-lateral cooperation of both legs, would be minimized in trained cyclists. Although field studies are needed to assess the possible implications, in terms of actual racing, of the new system, commonly used indicators of endurance cycling performance do not seem to be improved with the Rotor in trained cyclists.

Local and global calcium signals and fluid and electrolyte secretion in mouse submandibular acinar cells

Polarized Ca(2+) signals that originate at and spread from the apical pole have been shown to occur in acinar cells from lacrimal, parotid, and pancreatic glands. However, "local" Ca(2+) signals, that are restricted to the apical pole of the cell, have been previously demonstrated only in pancreatic acinar cells in which the primary function of the Ca(2+) signal is to regulate exocytosis. We show that submandibular acinar cells, in which the primary function of the Ca(2+) signal is to drive fluid and electrolyte secretion, are capable of both Ca(2+) waves and local Ca(2+) signals. The generally accepted model for fluid and electrolyte secretion requires simultaneous Ca(2+)-activation of basally located K(+) channels and apically located Cl(-) channels. Whereas a propagated cell-wide Ca(2+) signal is clearly consistent with this model, a local Ca(2+) signal is not, because there is no increase in intracellular Ca(2+) concentration at the basal pole of the cell. Our data provide the first direct demonstration, in submandibular acinar cells, of the apical and basal location of the Cl(-) and K(+) channels, respectively, and confirm that local Ca(2+) signals do not Ca(2+)-activate K(+) channels. We reevaluate the model for fluid and electrolyte secretion and demonstrate that Ca(2+)-activation of the Cl(-) channels is sufficient to voltage-activate the K(+) channels and thus demonstrate that local Ca(2+) signals are sufficient to support fluid secretion.

Examining the associations between physical work demands and work injury rates between men and women in Ontario, 1990-2000

AIMS

To describe the decline in injury rates between 1990 and 2000 within occupations stratified across three levels of physical demands and gender, adjusting for industry, in Canada's largest province.

METHODS

Records of injury compensation claims were obtained from the Ontario Workplace Safety & Insurance Board. The population likely to be insured by the Ontario Workplace Safety & Insurance Board was estimated from Statistics Canada's Labour Force Survey. Injury rates were calculated by three broad levels of physical demands, separately for men and women.

RESULTS

Injury rates decreased across each grouping of lower physical demands at work for both men and women, with the largest absolute differences in manual occupational groups (high physical demands). Occupations classified as manual (high physical demands) and mixed (moderate physical demands) showed larger differences in injury rates between genders than did non-manual (low physical demands), although the directions of these differences were not always consistent across different natures of injury classification.

CONCLUSIONS

The absolute reduction in injury rates in Ontario between 1990 and 2000 was dominated by the reduction in injury rates for men and women in manual and mixed occupations. However, not all types of injury have declined to the same extent. A large proportion of differences in injury rates between men and women can be attributed to the differential labour force participation across occupations and industries, as well as the differential tasks within occupational groups.

Meningoencephalitis in mice infected with an equine herpesvirus 1 strain KyA recombinant expressing glycoprotein I and glycoprotein E

One of the consequences of equine herpesvirus 1 (EHV-1) infection in the natural host is a neurological disease that can lead to paralysis. The pathology associated with EHV-1-induced neurological disease includes vasculitis of the small blood vessels within the central nervous system and subsequent damage to the surrounding neural tissue. In a previous study, an EHV-1 recombinant KyA virus (KgI/gE/75) was generated in which the sequences encoding glycoprotein I (gI) and glycoprotein E (gE) were repaired [Frampton et al. 2002 (Virus Research 90: 287-301)] using genes of the pathogenic EHV-1 strain 89c25. In contrast to the parental KyA virus that lacks gI and gE, the recombinant KgI/gE/75 was able to spread to the brains of CBA mice after intranasal infection. Infection resulted in a meningoencephalitis characterized by lymphocytic cuffing of small blood vessels within the brain, consistent with that observed in EHV-1-infected horses exhibiting neurological signs. KgI/gE/75 was able to elicit cytopathology in the lung prior to spread to the brain. However, like the attenuated KyA strain, KgI/gE/75 did not persist in the lung and was completely cleared from lung tissue by day 5 postinfection. We propose that gI and gE are neurovirulence factors for EHV-1, and that the CBA mouse model can be extended to study neurologic sequelae resulting after EHV-1 infection.

Putative anti-muscarinic antibodies cannot be detected in patients with primary Sjogren's syndrome using conventional immunological approaches

OBJECTIVE

To determine whether autoantibodies directed against muscarinic M3 receptors are present in the serum of patients with primary Sjogren's syndrome (pSS), and if so whether these autoantibodies inhibit secretion by intact salivary acinar cells.

METHODS

IgG was purified by affinity chromatography using protein G from sera collected from 15 patients with pSS. Antibody detection was by Western blotting, whole-cell enzyme-linked immunosorbent assay (ELISA) and immunoblotting. The antisecretory activity of the IgG faction was determined using fura-2 microfluorimetry to measure changes in intracellular Ca(2+) activity ([Ca(2+)](i)) in human and mouse salivary gland acinar cells and in Chinese hamster ovary (CHO) cells transfected with human M3 receptors (CHO-M3).

RESULTS

We found no specific M3 receptor recognition by the IgG fraction obtained from pSS patients using either Western blotting or ELISA or immunoblot techniques in which epitope conformation were preserved. Chronic exposure to pSS IgG had no effect on agonist-evoked Ca(2+) signals measured in human or mouse submandibular acinar cells or in CHO-M3 cells. However, acute application of IgG from Sjogren's syndrome patients produced a rapidly reversible reduction in the agonist-stimulated elevation in [Ca(2+)](i).

CONCLUSION

These data represent the first demonstration of salivary acinar cell inhibition by pSS IgG; however, this inhibition was found to be reversible. Our data also show that pSS IgG binding to M3R cannot be visualized by conventional immunological approaches.

HCMV activates PI(3)K in monocytes and promotes monocyte motility and transendothelial migration in a PI(3)K-dependent manner

Human cytomegalovirus (HCMV) is a leading cause of morbidity and mortality in immunocompromised hosts. In immunocompetent hosts, HCMV is associated with chronic inflammatory diseases including atherosclerosis. Monocytes and macrophages are proposed to play key roles in HCMV dissemination to host tissue, and their infection provides a biological link between the lifecycle of HCMV and disease pathology. We hypothesize that viral spread occurs via a mechanism in which infected peripheral blood monocytes, which are nonpermissive for viral replication, extravasate into host tissue and subsequently differentiate into permissive macrophages. Supporting this hypothesis, we recently showed that HCMV specifically induced the differentiation of monocytes into macrophages that become permissive for viral replication. To expand our understanding of HCMV pathogenesis, we next examined monocyte activation and migration, the first events in viral pathogenesis. We show here that HCMV up-regulates phosphatidylinositol 3,4,5 triphosphate kinase [PI(3)K] activity and that this increased PI(3)K activity is essential for infected monocyte-transendothelial migration. This increase in migration occurs through the up-regulation of cell motility in a PI(3)K-dependent process. Last, we show that these activated monocytes express a number of inflammatory mediators via PI(3)K signaling. We propose that the up-regulation of monocyte migration and immune mediators by HCMV infection is required for the hematogenous dissemination of the virus and as a consequence, could promote chronic inflammatory diseases associated with HCMV infection.

Cytokine profiles and long-term virus-specific antibodies following immunization of CBA mice with equine herpesvirus 1 and viral glycoprotein D

Equine herpesvirus 1 (EHV-1)-specific antibody-secreting cells (ASC) isolated from the lung and spleen of mice at 12 months after immunization with attenuated EHV-1 KyA, heat-killed KyA, or recombinant viral glycoprotein D (rgD) assessed by ELISPOT showed a three- to fivefold increase in three immunoglobulin isotypes at 3 days post-challenge with pathogenic EHV-1 RacL11 as compared to control mice. ELISPOT assays demonstrated a high frequency of cells secreting proinflammatory tumor necrosis factor-alpha (TNF-alpha), interferon gamma (IFN-gamma), and interleukin 4 (IL-4) in the lungs in response to infection with KyA or RacL11 or immunization with rgD. Cytokine production elicited by EHV-1 KyA or RacL11 infection revealed similar frequencies of EHV-1-specific IFN-gamma and IL-4 spot forming cells in the mediastinal lymph nodes and spleen. However, KyA induced significantly greater amounts of IFN-gamma producing cells in the lungs than did RacL11. Intranasal immunization with KyA or rgD induced long-term immunity that provided protection against pathogenic EHV-1 challenge infection at 12 months post-immunization. Overall, the data indicate that immunization with infectious KyA or rgD induces significant levels of cytokines, virus-specific ASC in the lungs and spleen, and long-term virus specific B-cell responses.

Reliability of a combined 3-min constant load and performance cycling test

Most fitness assessments either use a constant load to exhaustion (exercise capacity test) or an "all-out" effort (performance test). The purpose of this study was to determine the reliability of a high-intensity assessment that combined a constant load element with a performance test. Ten moderately trained male cyclists completed a ramp test to voluntary exhaustion in order to measure maximum minute power output (mean +/- s, 349.3 w +/- 55.0 w). On two other occasions subjects cycled at a constant load at maximum minute power output for 2-min immediately followed by a 1-min performance test. All tests were conducted on the subjects' own bicycles using a Kingcycle trade mark test rig. Power output was measured each second using SRM trade mark Power Cranks. The data were analysed by measuring the reliability of each 30 s of the 3-min test together with the peak power and the peak cadence achieved in the performance element of the test. There was no systematic bias in the data from trial 1 to trial 2 for any of the 6, 30 s blocks of the test, the peak power (mean, 95 % CI, 413.8 w, 357.8 - 469.7 w and 403.8 w, 339.9 - 467.6 w, trial 1 and trial 2, respectively) or peak cadence (95.0 rev x min(-1), 89.5 - 100.5 rev x min(-1) and 95.1 rev x min(-1), 90.0 - 100.1 rev x min(-1), trial 1 and trial 2, respectively). Mean (+/- s) total distance over the 3-min was 2.23 +/- 0.23 km and 2.26 +/- 0.26 km for trial 1 and trial 2 respectively (p > 0.05). The coefficients of variation ranged from 0.9 - 5.4 % and the intraclass correlation coefficients ranged from 0.96 - 0.99. It is concluded that in moderately trained subjects, the 3-min combination test provides reliable data and could therefore be used for short-term, high-intensity cycling intervention studies.

Odontoblast transport of sulphate--the in vitro influence of fluoride

The present study reports the development of a culture system for the analysis of 35S-sulphate release from odontoblasts in vitro. Pulpless longitudinally split rat incisors were cultured in supplemented minimum essential medium (alphaMEM) with 20 microCi 35S-sulphate per ml, 20 microCi 3H-mannitol per ml for 1h. Teeth were then transferred to fresh unlabelled media and aliquots of media were removed and the level of 35S-sulphate 3H-mannitol determined. Results indicated a two phase release of 35S-sulphate into the media, and comparison with pulp tissue indicated a specific release pattern. Transport of sulphate is essential for correct synthesis and glycosylation of macromolecules such as proteoglycans (PG). Previous studies have shown that post-translational modifications of these proteins can be influenced by excess fluoride, resulting in decreased sulphation and elongation of glycosaminoglycan (GAG) chains. Therefore the influence of fluoride on sulphate transport, using the optimised culture system was also investigated. Inclusion of 6mM fluoride during pulse labelling caused a significant decrease of 35S-sulphate (P<0.0001) during the initial release phase. Inclusion of 3 and 6mM fluoride only in the post-labelling incubation media resulted in a significant decrease in the release of 35S-sulphate (P<0.0001), during the total time course. The influence of fluoride was not dose dependent. Inclusion of a specific chloride channel blocker SITS, into the culture system indicated that 35S-sulphate transport may in part be via this route. Fluoride would therefore appear to influence the transport of 35S-sulphate across the odontoblast membrane, potentially via a chloride channel.

Contribution of gene products encoded within the unique short segment of equine herpesvirus 1 to virulence in a murine model

The pathogenesis of three equine herpesvirus 1 (EHV-1) recombinants was assessed in a CBA mouse model. Sequences encoding the majority of glycoproteins I (gI) and E (gE) were deleted from the pathogenic EHV-1 strain RacL11 (L11deltagIdeltagE), and sequences comprising the 3859 bp deletion within the strain KyA U(S) segment, which includes genes 73 (gI), 74 (gE), and 75 (putative 10 kDa protein 75), were re-inserted into attenuated KyA (KgI/gE/75). In addition, genes gE and 75 were inserted into KyA to generate the EHV-1 recombinant KgE/75. The insertion of the 3859 bp U(S) segment was sufficient to confer virulence to KyA, as indicated by pronounced signs of clinical disease including substantial weight loss. A large plaque morphology was observed in cells infected with KgI/gE/75 compared with KyA, and a small plaque phenotype was observed in cells infected with L11deltagIdeltagE compared with RacL11. These data indicate that gI and/or gI and gE contribute to the ability of EHV-1 to spread directly from cell-to-cell. The deletion of both gI and gE from the pathogenic RacL11 strain did not reduce clinical signs of disease in infected mice, but did decrease mortality compared with RacL11. Furthermore, the insertion of genes 74 (gE) and 75 into the vaccine strain KyA did not alter the attenuated phenotype of this virus. Finally, KgI/gE/75 and RacL11 elicited the production of the proinflammatory chemokines MIP-1alpha, MIP-1beta, and MIP-2 in the lungs of infected mice, while KyA did not, suggesting that gI and/or gI and gE contribute to the up-regulation of these mediators of inflammation. These findings show that gI, and/or gI and gE restore a virulent phenotype to the EHV-1 KyA strain, and indicate that virulence factors, in addition to gI and gE, contribute to the pathogenesis of the RacL11 strain.

Cryopreserved cells isolated from the adult canine olfactory bulb are capable of extensive remyelination following transplantation into the adult rat CNS

Naturally occurring spinal cord injury in dogs provides a potentially powerful intermediate model for testing the efficacy of therapeutic strategies developed in experimental rodent models before phase 1 trials in human patients. A particularly promising strategy involves transplantation of olfactory ensheathing cells (OECs) that both promote axon regeneration and generate new myelin sheaths. As a first step in developing OEC transplantation in the canine intermediate model we describe the isolation, purification, and characterization of OECs from adult dog olfactory bulb. We also show that the canine OEC behaves in a manner similar to its rodent counterpart following transplantation into demyelinating lesions in rat spinal cord and that these properties are retained following cryopreservation.

Subfornical organ neurons projecting to paraventricular nucleus: whole-cell properties

The subfornical organ (SFO) has been repeatedly identified as a CNS site that plays a critical role in sensing multiple physiological variables of the "milieu interieur" and, through efferent projections to other CNS sites, initiating physiological responses to change. Many recent in vitro patch-clamp studies have examined the cellular mechanisms underlying the sensory abilities of these specialized CNS neurons. The primary limitation of these studies, however, has been the inability to identify homogeneous groups of SFO neurons for such investigation. We report here the development of techniques to permit patch clamp recording from dissociated SFO neurons identified according to their in vivo projection site. SFO neurons were labeled by injection of fluorescently labeled, retrogradely transported microspheres into the hypothalamic paraventricular nucleus (PVN) 3 days prior to cell dissociation. Patch-clamp recordings from these SFO-PVN neurons revealed both sodium currents, potassium currents, action potentials, input resistance and membrane potential which were all similar to SFO cells prepared from animals with no prior tracer injection. Labeled SFO-->PVN cells were also found to be osmosensitive and responsive to angiotensin II, suggesting specific functional roles for this anatomically defined group of SFO neurons. Intriguingly, our post hoc analysis also demonstrated that all labeled neurons demonstrated a unique electrophysiological profile dominated by a large transient potassium conductance such that the transient/sustained potassium current ratio, or degree of inactivation was, on average, greater than 4.0. Utilization of these tracing techniques to permit the in vitro recording from cells with known in vivo connections will permit study of intrinsic mechanisms that underlie physiological responses of anatomically defined populations of neurons.

Satisfaction with medical rehabilitation in patients with cerebrovascular impairment

OBJECTIVE

Overall satisfaction has important social and economic implications for patients who have received inpatient medical rehabilitation. We conducted this study to examine the overall satisfaction level at 3- to 6-mo follow-up for inpatients with cerebrovascular impairments discharged from medical rehabilitation.

DESIGN

The study was retrospective using information from a national database representative of medical rehabilitation patients across the United States. Information submitted in 1997 and 1998 to the Uniform Data System for Medical Rehabilitation by 177 hospital and rehabilitation facilities from 40 states was examined. The final sample included 8,900 patient records. The main outcome measure was the level of satisfaction with medical rehabilitation at 80-180 days postdischarge follow-up.

RESULTS

A logistic regression model including ten independent variables was used to predict satisfied vs. dissatisfied at follow-up. Three statistically significant variables were included in the final model and correctly classified 95.1% of the patients. Higher FIM instrument discharge scores were associated with increased satisfaction. Further analysis of the FIM instrument subscales indicated that higher ratings in transfers, social cognition, and locomotion were significantly associated with increased satisfaction.

CONCLUSION

We identified several functional variables associated with increased satisfaction after medical rehabilitation in persons with stroke. The ability to objectively assess patient satisfaction is important as consumer-based outcome measures are integrated in accreditation and healthcare evaluation.

SCIP/Oct-6, Krox-20, and desert hedgehog mRNA expression during CNS remyelination by transplanted olfactory ensheathing cells

Olfactory ensheathing cells (OECs), although having a separate developmental origin to Schwann cells, are able to generate myelin sheaths following transplantation into areas of CNS demyelination that are remarkably similar to those made by Schwann cells. The transcriptional control of Schwann cell myelination has been well documented, in particular the role of SCIP/Oct-6 and Krox-20. It is not known, however, whether these transcription factors are also expressed when OECs assume a myelinating phenotype. In this study, we addressed this question by using a transplantation approach to generate myelinating OECs and then examined the expression of SCIP/Oct-6 and Krox-20 mRNA by in situ hybridization using oligonucleotide probes. We also examined the expression of desert hedgehog (Dhh), a Schwann cell-derived signaling molecule that is responsible for regulating the development of the connective tissue elements in peripheral nerve, which bear similarities to the morphologies adopted by nonmyelinating transplanted cells. Our results indicate that both Krox-20 and Dhh mRNA are strongly expressed by transplanted OECs, with SCIP mRNA present at much lower levels. The expression of Krox-20 relative to the expression of P0 mRNA by the transplanted OECs is consistent with its playing a similar role in OEC myelination to that in Schwann cell myelination, while the expression of Dhh suggests a possible mechanism for the diverse morphologies that cells adopt following OEC transplantation into the damaged CNS. Taken together, our results provide further evidence for the close similarity of OECs and Schwann cells and suggest that, despite their separate origins, the manner in which they generate a peripheral-type myelin sheath involves similar regulatory mechanisms.

The influence of crank rate on peak oxygen consumption during arm crank ergometry

The aim of this study was to assess the influence of three imposed crank rates on the attainment of peak oxygen consumption (VO2peak) and other physiological responses during incremental arm crank ergometry. Twenty physically active, although non-specifically trained, males volunteered for the study. They completed an exercise protocol using an electrically braked arm ergometer (Lode Angio, Groningen, Netherlands) at crank rates of 60, 70 and 80 rev x min(-1). The order of tests was randomized and they were separated by at least 2 days. Peak VO2 was significantly higher (P < 0.05) at 70 and 80 rev x min(-1) than at 60 rev x min(-1). Peak ventilation volume increased as a function of crank rate and was higher (P < 0.05) at 80 than at 60 rev x min(-1). Peak heart rate was higher (P < 0.05) at 70 and 80 rev x min(-1) than at 60 rev x min(-1). Furthermore, 70 and 80 rev x min(-1) resulted in an extended test time compared with 60 rev x min(-1). The greater physiological responses observed during the tests at the two faster crank rates might have been the result of a postponement of acute localized neuromuscular fatigue, allowing for more work to be completed. We recommend, therefore, that an imposed crank rate between 70 and 80 rev x min(-1) should be used to elicit VO2peak and other physiological responses in arm crank ergometry.

Rating of perceived exertion during high-intensity treadmill running

PURPOSE

The purpose of this investigation was 1) to evaluate the time course of the rating of perceived exertion (RPE; 6-20 Borg scale) during short-term, high-intensity, constant-load running (ST); and 2) to determine the reproducibility of RPE during ST.

METHODS

Fifteen well-trained males (VO2max = 58.0 +/- 4.6 mL x kg(-1) x min(-1), mean +/- SD) performed treadmill running (i.e., between 3 and 4 m.s-1 at 10.5% incline) to volitional exhaustion (Tlim) at an exercise intensity equivalent to 125% VO2max. A total of four RPE measurements were taken during each test, one every 30 s during the first 120 s of the exercise. The tests were repeated at the same time of day on three occasions within a 3-wk period.

RESULTS

Tlim for the three tests was 197.6 +/- 34.8 s. RPE was linearly related with exercise time (mean +/- SD for the three tests: RPE at 30 s = 10.8 +/- 2.2; RPE at 60 s = 12.6 +/- 1.8; RPE at 90 s = 14.5 +/- 1.7; RPE at 120 s = 16.0 +/- 1.9; RPE = 9.06 + (0.06 x time (s)); r = 0.71, SEE = 2.0, P < 0.01). Repeated ANOVA revealed no systematic bias between the three tests for RPE, and other measures of reliability were also favorable. These included intraclass correlation coefficients ranging from 0.78 to 0.87 and sample coefficients of variation of between 4.4% and 6.0%. The 95% limits of agreement ranged between 0.0 +/- 2.3 and 0.0 +/- 2.5.

CONCLUSION

ST RPE displays a positive linear response during the first 2 min. The measurement of ST RPE appears to be reliable and could thus add a new dimension to ST investigations.

Comparison of logistic regression and neural networks to predict rehospitalization in patients with stroke

CONTEXT

Rehospitalization following inpatient medical rehabilitation has important health and economic implications for patients who have experienced a stroke.

OBJECTIVE

Compare logistic regression and neural networks in predicting rehospitalization at 3-6-month follow-up for patients with stroke discharged from medical rehabilitation.

DESIGN

The study was retrospective using information from a national database representative of medical rehabilitation patients across the US.

SETTING

Information submitted to the Uniform Data System for Medical Rehabilitation from 1997 and 1998 by 167 hospital and rehabilitation facilities from 40 states was examined.

PARTICIPANTS

9584 patient records were included in the sample. The mean age was 70.74 years (SD = 12.87). The sample included 51.6% females and was 77.6% non-Hispanic White with an average length of stay of 21.47 days (SD = 15.47).

MAIN OUTCOME MEASURES

Hospital readmission from 80 to 180 days following discharge.

RESULTS

Statistically significant variables (P <.05) in the logistic model included sphincter control, self-care ability, age, marital status, ethnicity and length of stay. Area under the ROC curves were 0.68 and 0.74 for logistic regression and neural network analysis, respectively. The Hosmer-Lemeshow goodness-of-fit chi-square was 11.32 (df = 8, P = 0.22) for neural network analysis and 16.33 (df = 8, P = 0.11) for logistic regression. Calibration curves indicated a slightly better fit for the neural network model.

CONCLUSION

There was no statistically significant or practical advantage in predicting hospital readmission using neural network analysis in comparison to logistic regression for persons who experienced a stroke and received medical rehabilitation during the period of the study.

Characteristics of persons rehospitalized after stroke rehabilitation

OBJECTIVE

To develop classification models for risk of hospital readmission 80 to 180 days after discharge based the demographic and functional characteristics of persons discharged from acute inpatient rehabilitation after stroke.

DESIGN

Retrospective, using information from US facilities subscribing to the Uniform Data System for Medical Rehabilitation (UDS(MR)).

SETTING

Information submitted to the UDS(MR) from 1994 through 1996 by 167 hospital and rehabilitation facilities from 40 states was examined.

PARTICIPANTS

A total of 15,992 records of patients (mean age +/- standard deviation, 70.97 +/- 12.19yr) with a diagnosis of stroke were included in the final sample. The sample included 52.7% women and was 80% non-Hispanic white with an average length of stay (LOS) of 25.31 +/- 14.72 days.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Six subscales of the FIM instrument (self-care, sphincter control, transfers, locomotion, communication, social cognition), total FIM, and other predictor variables for regression analysis (gender, age, ethnicity, marital status, prehospital living setting, LOS, primary payer source, level of function-related group).

RESULTS

A logistic regression model included the following statistically significant variables (p <.05): ethnicity, sphincter control, self-care ability, gender, and LOS. The greatest variability occurred among men. Exactly 18.1% of non-Hispanic white men and 17.9% of African-American men were rehospitalized. In contrast, only 10.1% of Hispanic men and 11.4% of Asian men were rehospitalized. The odds of rehospitalization were lowest for Hispanic men.

CONCLUSION

As prospective payment systems are introduced for postacute care, it is important that the relationship among functional abilities, demographic characteristics, and incidence of hospital readmission following medical rehabilitation be examined.

The effect of immunosuppressive protocols on spontaneous CNS remyelination following toxin-induced demyelination

Glial cell transplantation is a potential therapy for human demyelinating disease, though obtaining large numbers of human myelinating cells for transplantation remains a major stumbling block. Autologous transplantation is currently not possible, since the adult human CNS is not a good source of oligodendrocyte precursors, and long-term immunosuppression of engrafted allogeneic or xenogeneic cells is therefore likely to be necessary. Immunosuppressive drugs may need to be used in situations where more recent, active areas of demyelination are undergoing endogenous remyelination. It is therefore pertinent to establish the extent to which immunosuppressive protocols will suppress spontaneous remyelination. In order to investigate this issue, we created demyelinating lesions in the spinal cord of adult rats and compared the extent of remyelination in animals receiving different immunosuppressive treatments. In animals given only cyclosporin A, there was no difference in the extent of either Schwann cell or oligodendrocyte remyelination of ethidium bromide-induced demyelinating lesions. However, in animals given cyclophosphamide, either alone or in combination with cyclosporin, there was a significant reduction in the extent of oligodendrocyte-mediated remyelination. These results demonstrate that cyclophosphamide is deleterious to oligodendrocyte remyelination and for this reason should be used with caution in patients with demyelinating disease.

SpL201: a conditionally immortalized Schwann cell precursor line that generates myelin

Dramatic progress has been made over recent years toward the elucidation of the mechanisms regulating lineage determination and cell survival in the developing peripheral nervous system. However, our understanding of Schwann cell development is limited. This is partly due to the difficulties in culturing primary Schwann cell precursor cells, the earliest developmental stage of the Schwann cell lineage defined to date. Both the inability to maintain cultured Schwann cell precursor cells in an undifferentiated state and the technical difficulties involved in their isolation have hampered progress. We have conditionally immortalized rat Schwann cell precursor cells using a retrovirally encoded EGFR/neu fusion protein to circumvent these problems and to generate a source of homogeneous cells. The resulting SpL201 cell line expresses p75 and nestin, two proteins expressed by neural crest-derived cells, as well as peripheral myelin protein 22, protein zero, and Oct-6 as markers of the Schwann cell lineage. When cultured in EGF-containing medium, the SpL201 cells proliferate and maintain an undifferentiated, Schwann cell precursor cell-like state. The cell line is dependent on EGF for survival but can differentiate into early Schwann cell-like cells in response to exogenous factors. Like primary rat Schwann cells, SpL201 cells upregulate Oct-6 and myelin gene expression in response to forskolin treatment. Furthermore, the SpL201 cell line can form myelin in the presence of axons in vitro and is capable of extensively remyelinating a CNS white matter lesion in vivo. Thus, this cell line provides a valuable and unique tool to study the Schwann cell lineage, including differentiation from the Schwann cell precursor cell stage through to myelination.

Vector volume analysis of the lower esophageal sphincter in achalasia and the effect of balloon dilation

Assessment of the effect of balloon dilation of the lower esophageal sphincter in achalasia currently relies on symptom scores, radiologic studies, or manometry. We have used vector volume analysis which constructs a three-dimensional (3D) pressure profile to examine the effects of balloon dilation on the sphincter. Studies were performed in 26 normal subjects and in 11 patients with achalasia in whom vector volume was determined before and/or after balloon dilation. Vector volume analysis was performed using a multilumen manometry catheter with eight side-reading ports. The catheter was withdrawn through the sphincter using a continuous pull-through technique. A 3D pressure profile was constructed. Vector volume of the lower esophageal sphincter shows a marked radial and linear asymmetry in normal subjects. 3D pressure profiles showed a symmetrical increase in lower esophageal sphincter pressure in untreated achalasia. Mean vector volumes pre and postdilation fell from 254 to 88 cm3 respectively. This was associated with a fall in the mean radial symmetry index from 0.83 to 0.76. Improvement in dysphagia occurred in those patients in whom pressure fell to 15 mmHg or below in at least three adjacent segments. This technique may be a useful tool in the assessment of patients with achalasia and postdilation results may help to predict the long-term outcome of treatment.

Bridging the divide: spinal cord repair by cellular transplantation--from research laboratory to therapeutic application

Spinal cord injury remains a clinical problem for which new therapeutic options are required. Recent developments in spinal cord injury research have suggested that promotion of axonal regeneration by cellular transplantation may be a feasible future treatment modality and it is possible that small animal clinical patients may be the first to benefit from these new approaches. This article describes the experiments which have generated this optimism and considers the steps that will be required to make the transition from laboratory experiments to clinical application.

An antigenomic strategy for treating heteroplasmic mtDNA disorders

In mammals, mitochondrial DNA (mtDNA) is the only autonomously replicating source of DNA outside the nucleus. Housed in the mitochondrial matrix, this molecule encodes thirteen polypeptides, all of which are believed to be essential components of the mitochondrial respiratory chain. Defects of the mitochondrial genome can cause severe neurological and multi-systemic disorders. As the genetic defect causes a dysfunction in the terminal stage of oxidative metabolism, there is little potential for pharmacological intervention. Thus, there is currently no effective therapy for these chronic progressive disorders. In the disease state, pathogenic mtDNA molecules often cohabit the same cell and tissue with wild type mtDNA, a situation termed heteroplasmy. Manifestation of biochemical and clinical defects occur only when a threshold level of heteroplasmy has been passed. The mitochondrial genome must be continually turned over. Consequently, if a pathogenic mtDNA molecule were to be targeted to prevent it from replicating, the wild type copy would be given a propagative advantage. Over time, therefore, the biochemical and, potentially, the clinical deficiency could be reversed. This manuscript summarises our attempts to identify such an antigenomic molecule, to localise this molecule to mitochondria and to assess its function in whole cells. Finally, we discuss the importance of identifying and designing new antigenomic molecules which may prove effective in treating patients with disorders of the mitochondrial genome.

Acetylcholine-evoked calcium mobilization and ion channel activation in human labial gland acinar cells from patients with primary Sjögren's syndrome

Recent evidence has indicated that the salivary gland dysfunction associated with Sjögren's syndrome (SjS) is not necessarily due to immune-mediated destruction of acinar tissue. SjS sufferers may possess substantial reserves of acinar tissue but nevertheless be incapable of maintaining salivary flow rates in the normal range. We have investigated the ability of isolated labial gland acinar cells from SjS patients to fluid secrete by measuring agonist-evoked changes in intracellular Ca(2+) ([Ca(2+)](i)) using fura-2 microfluorimetry and activation of K(+) and Cl(-) channels using the patch-clamp whole cell technique. We can confirm that stimulation with a super-maximal dose of acetylcholine (ACh) increased [Ca(2+)]i equally in both control acinar cells and those derived from SjS patients. However, at submaximal concentrations, the dose-response curve for ACh was shifted to the right by approximately one order of magnitude in acinar cells from SjS patients compared to control acinar cells. Patch-clamp measurements consistent with the presence of Ca(2+)-activated K(+) and Cl(-) conductances were obtained from both control acinar cells and those obtained from SjS patients. Dose-dependent activation of the ion channels by acetylcholine was also right-shifted in acinar cells from SjS patients compared to control cells. Our data show that labial gland acinar cells from SjS patients were capable of responding to agonist stimulation by mobilizing [Ca(2+)](i) and activating K(+) and Cl(-) channels consistent with the requirements of fluid secretion. However, the persistent loss of sensitivity to ACh observed in from SjS patients may account for the lack of saliva production observed in these patients in vivo.

Adrenomedullin acts in the rat paraventricular nucleus to decrease blood pressure

Adrenomedullin is a recently discovered peptide involved in the control of fluid and electrolyte homeostasis and cardiovascular function through peripheral and central nervous system actions. The present study was undertaken to examine the cardiovascular effects of adrenomedullin microinjection directly into the paraventricular nucleus (PVN). Microinjection of adrenomedullin into the PVN of urethane anaesthetized male Sprague-Dawley rats resulted in site-specific, repeatable decreases in blood pressure. These hypotensive effects were found to be dose related, and were not mediated by activation of calcitonin gene-related peptide receptors. These data suggest that adrenomedullin influences cardiovascular regulation through receptor mediated actions at the PVN of the hypothalamus.

Remyelinating the demyelinated CNS

The CNS has an inherent capacity to generate remyelinating cells following episodes of myelin loss. However, persistent demyelination is the major pathology of multiple sclerosis and the leucodystrophies, and is also a feature of spinal cord trauma. There are potentially two approaches for achieving remyelination in situations where it fails; enhancement of the inherent remyelinating capacity of the CNS, or transplantation of an exogenous source of myelin forming cells. In experimental animals it is possible to remyelinate demyelinated CNS axons by transplanting cultures containing central or peripheral myelinogenic cells. Glial cell transplantation may thus provide a therapeutic strategy for remyelinating areas of chronic demyelination as well as for stimulating axon regeneration. This presentation will review four issues that have to be addressed before glial transplantation can be undertaken in humans: is the procedure safe, what cells would be used, where would the cells come from and can we predict how much remyelination will be achieved? It concludes that the most promising approach will be to use multipotent neural precursor cells that have been committed to oligodendrocyte lineage differentiation prior to implantation. However, even with such preparations, which have considerable myelinating potential, the extent of remyelination that would be achieved can not yet be predicted with any degree of certainty.

Cranial design and function in a large theropod dinosaur

Finite element analysis (FEA) is used by industrial designers and biomechanicists to estimate the performance of engineered structures or human skeletal and soft tissues subjected to varying regimes of stress and strain. FEA is rarely applied to problems of biomechanical design in animals, despite its potential to inform structure-function analysis. Non-invasive techniques such as computed tomography scans can be used to generate accurate three-dimensional images of structures, such as skulls, which can form the basis of an accurate finite element model. Here we have applied this technique to the long skull of the large carnivorous theropod dinosaur Allosaurus fragilis. We have generated the most geometrically complete and complex FEA model of the skull of any extinct or extant organism and used this to test its mechanical properties and examine, in a quantitative way, long-held hypotheses concerning overall shape and function. The combination of a weak muscle-driven bite force, a very 'light' and 'open' skull architecture and unusually high cranial strength, suggests a very specific feeding behaviour for this animal. These results demonstrate simply the inherent potential of FEA for testing mechanical behaviour in fossils in ways that, until now, have been impossible.

Role of Ins(1,4,5)P3, cADP-ribose and nicotinic acid-adenine dinucleotide phosphate in Ca2+ signalling in mouse submandibular acinar cells

cADP-ribose (cADPr) and nicotinic acid-adenine dinucleotide phosphate (NAADP) are two putative second messengers; they were first shown to stimulate Ca(2+) mobilization in sea urchin eggs. We have used the patch-clamp whole-cell technique to determine the role of cADPr and NAADP in relation to that of Ins(1,4,5)P(3) in mouse submandibular acinar cells by measuring agonist-evoked and second-messenger-evoked changes in Ca(2+)-dependent K(+) and Cl(-) currents. Both Ins(1,4,5)P(3) and cADPr were capable of reproducing the full range of responses normally seen in response to stimulation with acetylcholine (ACh). Low concentrations of agonist (10-20 nM ACh) or second messenger [1-10 microM Ins(1,4,5)P(3) or cADPr] elicited a sporadic transient activation of the Ca(2+)-dependent currents; mid-range concentrations [50-500 nM ACh, 50 microM Ins(1,4,5)P(3) or 50-100 microM cADPr] elicited high-frequency (approx. 2 Hz) trains of current spikes; and high concentrations [more than 500 nM ACh, more than 50 microM Ins(1,4,5)P(3) or more than 100 microM cADPr] gave rise to a sustained current response. The response to ACh was inhibited by antagonists of both the Ins(1,4,5)P(3) receptor [Ins(1,4,5)P(3)R] and the ryanodine receptor (RyR) but could be completely blocked only by an Ins(1,4,5)P(3)R antagonist (heparin). NAADP (50 nM to 100 microM) did not itself activate the Ca(2+)-dependent ion currents, nor did it inhibit the activation of these currents by ACh. These results show that, in these cells, both Ins(1,4,5)P(3)R and RyR are involved in the propagation of the Ca(2+) signal stimulated by ACh and that cADPr can function as an endogenous regulator of RyR. Furthermore, although NAADP might have a role in hormone-stimulated secretion in pancreatic acinar cells, it does not contribute to ACh-evoked secretion in submandibular acinar cells.

Analysis of SAW propagation in gratings on ZnO/diamond substrates

The space harmonic method is used to analyze surface acoustic wave (SAW) propagation under an infinite periodic metal grating on ZnO/diamond composite layered substrates. Dispersion properties for shorted and open gratings are derived as a function of the thickness of the grating electrodes. From these dispersion relations, the coupling of modes (COM) parameters are derived. Energy profiles inside ZnO/diamond show that the energies contained in each of the ZnO and diamond layers are of the same order when the thickness of the ZnO layer is P/pi (P = grating period) and that the energy is contained within two wavelengths below the ZnO/diamond interface.

Dyadic Green's functions for multi-layer SAW substrates

Recent formulations of the dyadic (or generalized) Green's function describe the relationship between sources (both mechanical stresses and electrical charge) and waves (both mechanical displacements and acoustic potential) on the surface of a substrate. The 16 elements of the function intrinsically describe all propagation modes, whether Rayleigh or leaky, and are therefore, extremely useful in the design of surface acoustic wave devices. In addition to requiring little computational effort, the dyadic Green's function provides much more information than the traditional effective permittivity function. In this paper, we extend the calculation of the dyadic Green's function to multi-layer substrates. We show that its computation involves a simple cascaded matrix multiplication. The resulting function fully contains the substrate characteristics and, once obtained, can be used to describe the surface behavior with no further regard to the substrate's composition.

Length of stay and hospital readmission for persons with disabilities

OBJECTIVES

Length of stay (LOS) and hospital readmission for persons receiving medical rehabilitation were examined.

METHODS

A total of 96,473 patient records (1994-1998) were analyzed. Mean age of patients was 68.97 years; 61% were female and 83% were non-Hispanic White.

RESULTS

A decrease in LOS of 6.07 days (SD = 3.23) and increase in hospital readmission were found across all impairment groups (P < .001). Readmission increases ranged from 6.7% for amputations to 1.4% for orthopedic conditions. LOS was longer (2.1 days) for readmitted patients (P < .01). Age was not a significant predictor of rehospitalization.

CONCLUSIONS

Understanding variables associated with rehospitalization is important as prospective payment systems are introduced for postacute care.

An investigation of interactions between the immune system and stimulus-secretion coupling in mouse submandibular acinar cells. A possible mechanism to account for reduced salivary flow rates associated with the onset of Sjögren's syndrome

OBJECTIVES

To determine whether chronic exposure to lymphocyte-derived cytokines could inhibit the fluid secretory mechanism in salivary gland acinar cells and so account for the loss of gland function seen in the early stages of Sjögren's syndrome.

METHODS

Mouse submandibular acinar cells maintained in primary culture were exposed to a profile of cytokines produced by concanavalin A-activated splenic lymphocytes in vitro for periods up to 72 h. Agonist-evoked changes in intracellular Ca(2+) were determined microfluorimetrically in both control and cytokine-treated cells.

RESULTS

Acinar cells maintained in primary culture in the presence of cytokines for up to 72 h were able to mobilize intracellular calcium in response to stimulus by acetylcholine in an identical fashion to those maintained in primary culture in the absence of cytokines. Acute application of the conditioned medium produced by the activated lymphocytes had an antisecretory effect on acetylcholine-evoked Ca(2+) mobilization, which was found to be mediated by cholinesterase rather than by cytokines.

CONCLUSION

Neither chronic nor acute exposure to the profile of cytokines released by concanavalin A-activated splenic lymphocytes interfered in any way with the second messenger cascade and fluid and electrolyte secretion in acinar cells. Our data suggest an alternative hypothesis, in which elevated levels of cholinesterase can metabolize acetylcholine released within the salivary glands and thus prevent fluid secretion.

Severe murine lung immunopathology elicited by the pathogenic equine herpesvirus 1 strain RacL11 correlates with early production of macrophage inflammatory proteins 1alpha, 1beta, and 2 and tumor necrosis factor alpha

The CBA mouse model was used to investigate the immunopathology induced in the lung by the pathogenic equine herpesvirus 1 (EHV-1) strain RacL11 in comparison to infection with the attenuated vaccine candidate strain KyA. Intranasal infection with KyA resulted in almost no inflammatory infiltration in the lung. In contrast, infection with the pathogenic RacL11 strain induced a severe alveolar and interstitial inflammation, consisting primarily of lymphocytes, macrophages, and neutrophils. Infection with either EHV-1 strain resulted in the accumulation of similar numbers and ratios of CD4 and CD8 T lymphocytes in the lung and bronchoalveolar lavage (BAL) fluid. Further analysis of these T-cell populations revealed identical EHV-1-specific cytotoxic T-lymphocyte responses. RNase protection analysis of RNA isolated from the BAL fluid of RacL11-infected mice on day 3 postinfection revealed much higher levels of RNA specific for macrophage inflammatory protein 1alpha (MIP-1alpha), MIP-1beta, and MIP-2 than were observed for KyA-infected mice. Furthermore, significantly higher levels of transcripts specific for tumor necrosis factor alpha were induced on day 3 postinfection with RacL11 compared with KyA. These findings suggest that the early production of proinflammatory beta chemokines plays a major role in the severe, most often lethal, respiratory inflammatory response induced by the pathogenic EHV-1 strain RacL11.

Porcine neural progenitors require commitment to the oligodendrocyte lineage prior to transplantation in order to achieve significant remyelination of demyelinated lesions in the adult CNS

Glial cell transplantation is a potential therapy for human demyelinating disease, though obtaining large numbers of oligodendrocyte precursors from nonrodent species is currently problematic. Culturing of multipotent neural progenitors may provide a solution to this problem, because these cells can be expanded in vitro whilst retaining the ability to differentiate into both neurons and glial cells. In order to investigate the myelinating capability of multipotent neural progenitors, we isolated cells from the porcine subventricular zone, a region rich in neural progenitors, and transplanted them into areas of persistent demyelination in the spinal cord of immunosuppressed rats, created by the injection of ethidium bromide and subsequent exposure to 40 Gy X-irradiation. Porcine SVZ cells were transplanted either within 12 h of isolation or after 7 days in B104-conditioned medium. Freshly isolated cells did not mature into myelinating oligodendrocytes following transplantation and instead remained as clusters of undifferentiated progenitors. However, cells exposed to B104-conditioned medium prior to transplantation were able to effect complete remyelination of the demyelinated axons. This suggests that neural progenitors must be manipulated in vitro for commitment to the oligodendrocyte lineage prior to transplantation if significant remyelination is to be achieved.

Atkinson tubes are a good cost-effective means of palliating inoperable oesophageal malignant strictures: an eight-year experience

OBJECTIVE

To determine how many oesophageal and oesophago-gastric malignancies could be successfully intubated endoscopically with an Atkinson tube, and how often a metal mesh tube would be required instead.

DESIGN

A consecutive series of 125 patients underwent endoscopy and intubation.

METHODS

A total of 142 Atkinson tubes were inserted into 122 patients, and four metal mesh stents were put into three patients. The median hospital stay was 3 days, and 28 patients were treated as day cases.

RESULTS

Atkinson tube insertion failed in only one patient. There were eight oesophageal perforations (5.6%); the procedure-related mortality was 4%. Three patients required a metal mesh stent, as dilatation proved difficult because of prior radiotherapy in two and prior surgery in one.

CONCLUSION

Atkinson tubes are the stents of choice for inoperable oesophageal tumours because of low complication rates and cost efficiency. In 20% of patients, day case insertion was successful. Metal mesh stents should be reserved for those patients with tight post-radiotherapy or post-surgical strictures when dilatation is difficult.

Reproducibility of the maximum accumulated oxygen deficit and run time to exhaustion during short-distance running

The aim of this study was to determine the reproducibility of the maximal accumulated oxygen deficit and the associated exercise time to exhaustion during short-distance running. Fifteen well-trained males (mean +/- s: VO2max = 58.0+/-4.6 ml x kg(-1) x min(-1)) performed the maximum accumulated oxygen deficit test at an exercise intensity equivalent to 125% VO2max. The test was repeated at the same time of day on three occasions within 3 weeks. There was no significant systematic bias between trials for either maximum accumulated oxygen deficit (man +/- s: trial 1 = 69.0+/-13.1; trial 2 = 71.4+/-12.5; trial 3 = 70.4+/-15.0 ml O2 Eq x kg(-1); ANOVA, F = 0.70, PP= 0.51) or exercise time to exhaustion (trial 1 = 194 + 31.1; trial 2 = 198 + 33.2; trial 3 = 201 + 36.8 s; F= 1.49, P = 0.24). In addition, other traditional measures of reliability were also favourable. These included intraclass correlation coefficients of 0.91 and 0.87, and sample coefficients of variation of 6.8% and 5.0%, for maximum accumulated oxygen deficit and exercise time to exhaustion respectively. However, the '95% limits of agreement' were 0+/-15.1 ml O2 Eq (1.01 multiply/divide 1.26 as a ratio) and 0+/-33.5 s (1.0 multiply/divide 1.18 as a ratio) for maximum accumulated oxygen deficit and exercise time to exhaustion respectively. We estimate that the sample sizes required to detect a 10% change in exercise time to exhaustion and maximum accumulated oxygen deficit after a repeated measures experiment are 10 and 20 respectively. Unlike the results of previous maximum accumulated oxygen deficit studies, we conclude that it is not a reliable measure.