Mean Arc Distance (MAD): a quantity to compare trajectory 4πsampling in single target cranial stereotactic radiotherapy

Purpose:C-arm linac-based radiotherapy has seen a recent interest in 4 methods of delivery using simultaneous rotations of couch and gantry to reduce doses to organs-at-risk (OARs) and increase dose compactness. While many methods use heuristics to generate trajectories that avoid OARs, combined with arbitrary trajectory restrictions to prevent oversampling, a quantity has not yet been developed to succinctly compare sampling of the 4 space for candidate trajectories as a surrogate for dosimetric compactness.Methods:Evenly spaced sampling points were distributed across a 4 sphere centred on isocentre. A metric, mean arc distance (MAD), was defined that quantifies the average arc distance between all fields in a radiotherapy trajectory and their nearest sampling point. The relationship between isodose volume and MAD was examined in 2,047 plans: 900 unique trajectories of fixed port DCA plans, 900 unique trajectories of contiguous field DCA plans, 192 VMAT plans (eight volumes in four locations, each with six trajectories) in matRad with 5 VMAT plans repeated for validation in a clinical planning system, and 10 clinical VMAT cases replanned with five trajectories in a clinical treatment planning system.Results:All isodose volumes greater than 10 % of the prescription dose decreased with decreasing MAD in all comparisons. In the range of 10 % to 100 % of the prescription dose, the rate of isodose volume decrease was exponential as a function of MAD in all comparisons. Reduction of absolute isodose volume is seen with increased 4 sampling, with larger target volumes exhibiting larger absolute reductions. Very low isodoses (0 % to 10 % of prescription) increased with decreasing MAD.Conclusions:MAD is a 4 sampling quantity useful in quantifying the decrease of isodose volume, relevant for sparing normal tissues. By quantifying this feature, candidate dynamic trajectories can be efficiently compared for 4 sampling. This quantity is explored here for single target cranial radiotherapy but may have applications to other radiotherapy treatment site.

Spectrum of MRI brain lesion patterns in neuromyelitis optica spectrum disorder: a pictorial review

Neuromyelitis optica is a neurotropic autoimmune inflammatory disease of the central nervous system traditionally thought to exclusively involve the optic nerves and spinal cord. With the discovery of the disease-specific aquaporin-4 antibody and the increasing recognition of clinical and characteristic imaging patterns of brain involvement in what is now termed neuromyelitis optica spectrum disorder (NMOSD), MRI now plays a greater role in diagnosis of NMOSD based on the 2015 consensus criteria and in distinguishing it from other inflammatory disorders, particularly multiple sclerosis (MS). Several brain lesion patterns are highly suggestive of NMOSD, whereas others may serve as red flags. Specifically, long corticospinal lesions, hemispheric cerebral white matter lesions and periependymal lesions in the diencephalon, dorsal brainstem and white matter adjacent to lateral ventricles are typical of NMOSD. In contrast, juxtacortical, cortical, or lesions perpendicularly oriented to the surface of the lateral ventricle suggests MS as the diagnosis. Ultimately, a strong recognition of the spectrum of MRI brain findings in NMOSD is essential for accurate diagnosis, and particularly in differentiating from MS. This pictorial review highlights the spectrum of characteristic brain lesion patterns that may be seen in NMOSD and further delineates findings that may help distinguish it from MS.

Intrapatient study comparing 3D printed bolus versus standard vinyl gel sheet bolus for postmastectomy chest wall radiation therapy

PURPOSE

This patient study evaluated the use of 3-dimensional (3D) printed bolus for chest wall radiation therapy compared with standard sheet bolus with regard to accuracy of fit, surface dose measured in vivo, and efficiency of patient setup. By alternating bolus type over the course of therapy, each patient served as her own control.

METHODS AND MATERIALS

For 16 patients undergoing chest wall radiation therapy, a custom 5.0 mm thick bolus was designed based on the treatment planning computed tomography scan and 3D printed using polylactic acid. Cone beam computed tomography scanning was used to image and quantify the accuracy of fit of the 2 bolus types with regard to air gaps between the bolus and skin. As a quality assurance measure for the 3D printed bolus, optically stimulated luminescent dosimetry provided in vivo comparison of surface dose at 7 points on the chest wall. Durations of patient setup and image guidance were recorded and compared.

RESULTS

In 13 of 16 patients, the bolus was printed without user intervention, and the median print time was 12.6 hours. The accuracy of fit of the bolus to the chest wall was improved significantly relative to standard sheet bolus, with the frequency of air gaps 5 mm or greater reduced from 30% to 13% (P < .001) and maximum air gap dimension diminished from 0.5 ± 0.3 to 0.3 ± 0.3 mm on average. Surface dose was within 3% for both standard sheet and 3D printed bolus. On average, the use of 3D printed bolus reduced the setup time from 104 to 76 seconds.

CONCLUSIONS

This study demonstrates 3D printed bolus in postmastectomy radiation therapy improves fit of the bolus and reduces patient setup time marginally compared with standard vinyl gel sheet bolus. The time savings on patient setup must be weighed against the considerable time needed for the 3D printing process.

Advancing the framework for considering the effects of climate change on worker safety and health

In 2009, a preliminary framework for how climate change could affect worker safety and health was described. That framework was based on a literature search from 1988-2008 that supported seven categories of climate-related occupational hazards: (1) increased ambient temperature; (2) air pollution; (3) ultraviolet radiation exposure; (4) extreme weather; (5) vector-borne diseases and expanded habitats; (6) industrial transitions and emerging industries; and (7) changes in the built environment. This article reviews the published literature from 2008-2014 in each of the seven categories. Additionally, three new topics related to occupational safety and health are considered: mental health effects, economic burden, and potential worker safety and health impacts associated with the nascent field of climate intervention (geoengineering). Beyond updating the literature, this article also identifies key priorities for action to better characterize and understand how occupational safety and health may be associated with climate change events and ensure that worker health and safety issues are anticipated, recognized, evaluated, and mitigated. These key priorities include research, surveillance, risk assessment, risk management, and policy development. Strong evidence indicates that climate change will continue to present occupational safety and health hazards, and this framework may be a useful tool for preventing adverse effects to workers.

The use of personal flotation devices in the Northeast lobster fishing industry: An examination of the decision-making process

BACKGROUND

This study explored perspectives of Northeast commercial lobstermen regarding the use of personal flotation devices (PFDs). Researchers sought to identify factors contributing to low PFD use, and motivators that could lead to increased use of PFDs.

METHODS

This qualitative research (n = 72) included 25 commercial fishermen who participated in in-depth, semi-structured interviews, and 47 attendees of Lobstermen's meetings who engaged in focus groups.

RESULTS

The results showed substantial barriers to PFD use. Fishermen described themselves as being proactive about safety whenever possible, but described a longstanding tradition of not wearing PFDs. Key factors integrally linked with the lack of PFD use were workability, identity/social stigma, and risk diffusion.

CONCLUSION

Future safety interventions will need to address significant barriers to PFD use that include issues of comfort and ease of use, as well as social acceptability of PFDs and reorientation of risk perceptions related to falls overboard.

The Adolescent Mentalization-based Integrative Treatment (AMBIT) approach to outcome evaluation and manualization: adopting a learning organization approach

AMBIT (Adolescent Mentalization-Based Integrative Treatment) is a developing team approach to working with hard-to-reach adolescents. The approach applies the principle of mentalization to relationships with clients, team relationships and working across agencies. It places a high priority on the need for locally developed evidence-based practice, and proposes that outcome evaluation needs to be explicitly linked with processes of team learning using a learning organization framework. A number of innovative methods of team learning are incorporated into the AMBIT approach, particularly a system of web-based wiki-formatted AMBIT manuals individualized for each participating team. The paper describes early development work of the model and illustrates ways of establishing explicit links between outcome evaluation, team learning and manualization by describing these methods as applied to two AMBIT-trained teams; one team working with young people on the edge of care (AMASS - the Adolescent Multi-Agency Support Service) and another working with substance use (CASUS - Child and Adolescent Substance Use Service in Cambridgeshire). Measurement of the primary outcomes for each team (which were generally very positive) facilitated team learning and adaptations of methods of practice that were consolidated through manualization.

Case report: cytokine and CD4+ T-cell profiles of monozygotic twins with autism and divergent comorbidities and drug treatment

Autism spectrum disorders are neurodevelopmental disorders that are thought to be caused by a gene-by-environment interaction and in which various immune alterations are reported. We investigate CD4(+) T-cell cytokine profiles and subpopulations in 19-year-old monozygotic twins with autism and different comorbidities. CD4(+) T cells from the twin with epilepsy produce more interferon-gamma, less interleukin-17, and have an increased interferon-γ/interleukin-4 ratio. CD4(+) T cells from the twin with multiple sclerosis exhibit a cytokine profile similar to an age and gender-matched control and a higher percentage of T regulatory (Treg) cells. The twins' mother's T cells produce very high levels of both interleukin-17 and interferon-γ. Cytokine and CD4(+) T-cell abnormalities in the twins could contribute to or be a result of the manifestation of their divergent comorbidities. A proinflammatory, autoimmune-polarized cytokine profile is observed in this unique family with autism.

A microfluidic shear device that accommodates parallel high and low stress zones within the same culturing chamber

Fluid shear stress (FSS) plays a critical role in regulating endothelium function and maintaining vascular homeostasis. Current microfluidic devices for studying FSS effects on cells either separate high shear stress zone and low shear stress zone into different culturing chambers, or arranging the zones serially along the flow direction, which complicates subsequent data interpretation. In this paper, we report a diamond shaped microfluidic shear device where the high shear stress zone and the low shear stress zone are arranged in parallel within one culturing chamber. Since the zones with different shear stress magnitudes are aligned normal to the flow direction, the cells in one stress group are not substantially affected by the flow-induced cytokine/chemokine releases by cells in the other group. Cell loading experiments using human umbilical vein endothelial cells show that the device is able to reveal stress magnitude-dependent and loading duration-dependent cell responses. The co-existence of shear stress zones with varied magnitudes within the same culturing chamber not only ensures that all the cells are subject to the identical culturing conditions, but also allows the resemblance of the differential shear stress pattern in natural arterial conditions. The device is expected to provide a new solution for studying the effects of heterogeneous hemodynamic patterns in the onset and progression of various vascular diseases.

Selective responses of myenteric neurons to oxidative stress and diabetic stimuli

BACKGROUND

Diabetes has a differential effect on different subpopulations of myenteric neurons. Our aim was to investigate an in vitro model to examine the pathways underlying the development of nerve changes in diabetes.

METHODS

The proportions of neuronal cell bodies containing vasoactive intestinal polypeptide (VIP), neuronal nitric oxide synthase (nNOS) and calbindin relative to the pan-neuronal marker HuC/D were quantified in wholemount preparations of the myenteric plexus of adult rat ileum using double labeling immunohistochemistry. Preparations were maintained in culture for 24 h in the presence and absence of stimuli mimicking the diabetic environment including oxidative stress, carbonyl stress, high glucose and advanced glycation end products (AGEs). Data were compared with the effect of streptozotocin-induced diabetes in vivo. KEY RESULTS Only oxidative stress in vitro produced the same pattern as observed in diabetes with an increase in VIP-, decrease in nNOS-, and no change in calbindin-positive neurons. Carbonyl stress and high glucose caused an increase in VIP-containing neurons without affecting nNOS expression. In contrast, exposure to AGEs only caused a decrease in nNOS-positive neurons. Calbindin expression was unaffected by any of the stimuli. The effects of the stimuli were prevented by the antioxidant, α-lipoic acid, or the carbonyl scavenger, aminoguanidine.

CONCLUSIONS & INFERENCES

The results provide evidence that oxidative stress is the common factor in the development of neuronal changes in diabetes; however, the mechanism by which oxidative stress occurs depends on the individual subpopulation of myenteric neurons examined. The presence of calbindin appears to protect myenteric neurons against harmful stimuli.

Effects of equine grass sickness on sympathetic neurons in prevertebral and paravertebral ganglia

Acute equine grass sickness (EGS) is a fatal disease of horses that is thought to be due to ingestion of a neurotoxic agent causing extensive damage to autonomic neurons. The aim of this study was to compare the effects of EGS on neurons in two sympathetic ganglia, the paravertebral cranial cervical ganglion (CCG) and the prevertebral coeliac/cranial mesenteric ganglion (CG/CMG). Specimens from horses with EGS and controls were obtained post mortem and processed using single and double immunofluorescence labelling for PGP 9.5 and HuC/HuD (pan-neuronal markers), TUNEL and caspase 3 (markers for apoptosis), vasoactive intestinal polypeptide (VIP) and galanin (markers of the cell body response to injury following axotomy or exposure to sympathetic neurotoxins) and tyrosine hydroxylase (TH, marker for noradrenaline synthesis). In control horses, all neurons contained PGP 9.5 and HuC/HuD. There was a significant loss of PGP 9.5 and HuC/HuD expression in samples from horses with EGS that occurred to a greater extent in the CG/CMG than the CCG. The number of caspase 3-positive neurons increased significantly in both ganglia, but TUNEL staining of sympathetic neurons was only significantly increased in the CG/CMG in EGS. No VIP was observed in any ganglia; however, there was a significant increase in galanin-positive neurons in both ganglia in EGS. In the CCG, there was a significant shift towards increased fluorescence intensity for TH, possibly indicating an initial accumulation of TH within the cell body. In contrast, TH fluorescence intensity was significantly reduced in the CG/CMG in EGS correlating with the greater loss of neurons. These results demonstrate that EGS can induce a cell body response that is similar to the response of sympathetic neurons to a chemical neurotoxin. EGS also causes loss of sympathetic neurons, some of which occurs via apoptosis. Changes were more marked in the CG/CMG than the CCG indicating that the prevertebral ganglia were affected earlier than the paravertebral ganglia in the pathological process and had undergone greater neurodegeneration.

Efficacy of treatment of MS with IFNbeta-1b or glatiramer acetate by monthly brain MRI in the BECOME study

BACKGROUND

There are no published MRI studies comparing interferon beta 1b (IFNbeta-1b) and glatiramer acetate (GA) for treatment of relapsing multiple sclerosis (MS).

OBJECTIVE

To compare the efficacy of IFNbeta-1b and GA for suppression of MS disease activity as evidenced on frequent brain MRI.

METHODS

A total of 75 patients with relapsing-remitting MS or clinically isolated syndromes were randomized to standard doses of IFNbeta-1b or GA and followed by monthly brain MRI for up to 2 years with a protocol optimized to detect enhancement. The primary outcome was the number of combined active lesions (CAL) per patient per scan during the first year, which included all enhancing lesions and nonenhancing new T2/fluid-attenuated inversion recovery (FLAIR) lesions. Secondary outcomes were the number of new lesions and clinical exacerbations over 2 years.

RESULTS

Baseline characteristics were similar between the groups. The primary outcome showed similar median (75th percentile) CAL per patient per scan for months 1-12, 0.63 (2.76) for IFNbeta-1b, and 0.58 (2.45) for GA (p = 0.58). There were no differences in new lesion or clinical relapses for 2 years. Only 4.4% of CAL on monthly MRI scans were nonenhancing new T2/FLAIR lesions.

CONCLUSION

Patients with relapsing multiple sclerosis randomized to interferon beta 1b or glatiramer acetate showed similar MRI and clinical activity.

Young people at risk of offending: their views on a specialist mental health service in south east London

This article explores the views of young people regarding their involvement with a specialist mental health service for adolescents who offend or are at risk of offending. The main aims are to shed light on means of engaging this group in therapeutic work, and to illustrate the use of qualitative techniques in the evaluation of health services. Twenty clients and ex-clients were interviewed using a semistructured schedule. Responses were analysed using a thematic indexing technique. Findings show that the majority felt the service had helped them to some extent, despite initial resistance to referral. Five factors which helped practitioners overcome this resistance were identified: (1) A manner which demonstrates respect and commitment; (2) being able to operate flexibly and offer outreach appointments; (3) clinical effectiveness; (4) making therapeutic sessions seem personally relevant; and (5) explaining clearly the role of the service. Attention should be paid to these areas if mental health services are to support this challenging client group.

Engineering and public health at CDC

Engineering is the application of scientific and technical knowledge to solve human problems. Using imagination, judgment, and reasoning to apply science, technology, mathematics, and practical experience, engineers develop the design, production, and operation of useful objects or processes. During the 1940s, engineers dominated the ranks of CDC scientists. In fact, the first CDC director, Assistant Surgeon General Mark Hollis, was an engineer. CDC engineers were involved in malaria control through the elimination of standing water. Eventually the CDC mission expanded to include prevention and control of dengue, typhus, and other communicable diseases. The development of chlorination, water filtration, and sewage treatment were crucial to preventing waterborne illness. Beginning in the 1950s, CDC engineers began their work to improve public health while developing the fields of environmental health, industrial hygiene, and control of air pollution. Engineering disciplines represented at CDC today include biomedical, civil, chemical, electrical, industrial, mechanical, mining, and safety engineering. Most CDC engineers are located in the National Institute for Occupational Safety and Health (NIOSH) and the Agency for Toxic Substances and Disease Registry (ATSDR). Engineering research at CDC has a broad stakeholder base. With the cooperation of industry, labor, trade associations, and other stakeholders and partners, current work includes studies of air contaminants, mining, safety, physical agents, ergonomics, and environmental hazards. Engineering solutions remain a cornerstone of the traditional "hierarchy of controls" approach to reducing public health hazards.

Alveolar macrophage activation by myeloperoxidase: a model for exacerbation of lung inflammation

Inflammation of the lung is characterized by the influx of increased numbers of various leukocytes including polymorphonuclear leukocyte (PMN) neutrophils. In addition to cells, numerous studies have pointed to the role of tumor necrosis factor-alpha in the inflammatory process. This study addresses a previously unrecognized interaction between neutrophil-derived myeloperoxidase (MPO) and resident alveolar macrophages (AMø). Rat AMø exposed to either enzymatically active recombinant MPO or enzymatically inactive MPO (iMPO) exhibited an increased respiratory burst (RB). When iMPO was employed, the enhancement of the RB was greater than that observed with MPO. Although the RB was greater with iMPO, macrophage (Mø)-mediated intracellular candidic activity was equivalent for both MPO and iMPO. It is known that pro- inflammatory cytokines contribute to the inflammatory process. When rat AMø were exposed to both forms of myeloperoxidase, iMPO demonstrated greater upregulation of cytokine genes as well as product. These data suggest that at the site of inflammation, neutrophil-derived MPO and iMPO stimulate AMø, resulting in an increased inflammatory and cytotoxic state, and thereby contributing to the general lung inflammatory response.

Improving safety in the Alaskan commercial fishing industry

OBJECTIVES

Over 90% of deaths in Alaska's commercial fishing industry were due to drowning, following vessel sinkings. In the early 1990's, the U.S. Commercial Fishing Industry Vessel Safety Act required the implementation of safety measures for all fishing vessels. The purpose of our study was to examine the effectiveness of these measures in reducing the high fatality rate of Alaska's commercial fishermen.

STUDY DESIGN

Alaska Occupational Injury Surveillance System and AlaskaTrauma Registry data were used to examine fishing fatalities and injuries. Demographic, risk factor, and incident data were analyzed for trend.

RESULTS

During 1991-1998, there was a significant (p<0.001) (decrease in Alaskan commercial fishing deaths. Significant progress has been made in saving lives of fishermen involved in vessel sinkings. During 1991-1997, 536 fishermen suffered severe injuries (437/100,000/year). These injuries resulted from being entangled, struck or crushed by equipment (60%) and from falls (25%).

CONCLUSIONS

Vessel sinkings still continue to occur, placing fishermen at substantial risk. Efforts toward improving vessel stability and hull integrity and avoidance of harsh weather conditions must be made to further reduce the fatality rate. The nature of non-fatal injuries reflect that modern fishing vessels are complex industrial environments posing multiple hazards. Measures are needed to prevent falls and improve equipment handling and machinery guarding.

Characterisation of Wnt gene expression during the differentiation of murine embryonic stem cells in vitro: role of Wnt3 in enhancing haematopoietic differentiation

The first haematopoietic stem cells in mammalian and non-mammalian vertebrates are derived from mesoderm, therefore genes that are important in mesoderm patterning and formation might also play an essential role in haematopoietic stem cell commitment and differentiation. Several members of the Wnt gene family are expressed in very specific patterns in embryonic mesoderm and have previously been shown to act as haematopoietic growth factors. In order to investigate in detail the role that such secreted proteins play in the biology of early haematopoietic commitment we have used in vitro differentiation of murine embryonal stem (ES) as a model system. Using reverse-transcriptase polymerase chain reaction analysis we identified several candidate Wnt genes whose expression pattern was consistent with a role in generation, maintenance and/or differentiation of early haematopoietic progenitor cells including three genes previously shown to have a role in haematopoiesis (Wnt5a, Wnt2b and Wnt10b). The most interesting candidate was Wnt3, because of its strong and regulated expression during in vitro differentiation of murine ES cells as well as its early embryonic expression in mesoderm. Overexpression of Wnt3 was sufficient to cause a consistent increase in the number of embryoid bodies committing to haematopoiesis further strengthening the evidence that this protein can enhance haematopoietic commitment during in vitro differentiation of ES cells. In addition, overexpression of Wnt3 caused a marked upregulation of Brachyury expression, thus providing some evidence that Brachyury may be one of the target genes for the Wnt3 signalling pathway.

mTert expression correlates with telomerase activity during the differentiation of murine embryonic stem cells

Telomerase, the enzyme which maintains the ends of linear chromosomes in eukaryotic cells, is found at low levels in somatic stem cells but while this is incapable of preventing the progressive erosion of telomeres occurring as a consequence of cell division, such cells show greater proliferative capacity than normal somatic cells hence examination of telomerase activity in such stem cells is of interest. Our aim in this work was to examine the relationship between expression of the reverse transcriptase component (mTert) of murine telomerase. We report here the insertion of a reporter cassette comprising a segment of the promoter sequence of murine Tert gene coupled to the coding sequence of green fluorescent protein (GFP) into murine embryonic stem (ES) cells and show that this is sufficient for mimicking the expression of mTert. We show that the expression of mTert is very closely linked to telomerase activity and that both are substantially reduced upon differentiation of ES cells into more committed lineages giving us a potential reporter system for the selection and isolation of ES cells possessing different levels of telomerase activity.

The endothelium and cytokine secretion: the role of peroxidases as immunoregulators

The endothelium is frequently exposed to many proinflammatory mediators. The present study was done to determine the effects of human recombinant myeloperoxidase (MPO) and porcine eosinophil peroxidase (EPO) on certain endothelial cell (HUVEC) functions. The following areas were evaluated: (1) production of reactive oxygen intermediates (ROI), (2) cytokine secretion, and (3) regulation of mRNA cytokine transcripts. Both MPO and EPO induced the production of ROI, but an enzymatically inactive form of MPO (iMPO) was the most effective. Enzymatically inactive MPO, but not MPO, induced the secretion of interleukins 6 and 8 and granulocyte-monocyte colony-stimulating factor. A ribonuclease protection assay indicated that both iMPO and MPO upregulated mRNA cytokine transcripts; however, the former was markedly more effective. The simultaneous addition of EPO and iMPO resulted in a decrease in cytokine-specific mRNA. These data indicate a major role for peroxidases in the regulation of inflammation.

Mitogenic activity of steroidogenesis-inducing protein (SIP) during hypoxic stress of human ovarian carcinoma cells

Steroidogenesis-inducing protein (SIP) is a novel growth factor isolated from human ovarian follicular fluid. While the steroidogenic and mitogenic effects appear to be restricted towards gonadal cell types, we have recently demonstrated that SIP is also a potent mitogen for cell lines derived from ovarian surface epithelial carcinomas. Here, we demonstrate that SIP reverses hypoxia-induced cell proliferation arrest of the human ovarian carcinoma cell line SKA, as determined by flow cytometry and cell proliferation assays. Concomitant with this reversal of proliferation arrest is an increase in expression of cyclins D and E and a reduction in expression of the cyclin-dependent kinase inhibitor p27. Pretreatment of hypoxic SKA cells with SIP is also shown to increase Taxol sensitivity of these cells by two-fold. These studies further characterize the mitogenic activity of SIP at the molecular level and suggest that this protein may be an effective biological response modifier for ovarian carcinoma cells.

Postnatal development of nitric oxide synthase activity in fast and slow muscles of the rat

Nitric oxide synthase (NOS) activity was measured in extensor digitorum longus (EDL) and soleus muscles during postnatal development in the rat. At 1 and 2 weeks of age, similar low levels were found in both muscles. After 2 weeks, activity increased significantly only in EDL. Adult NOS activity was significantly higher in EDL than soleus. Thus, the preferential expression of NOS in fast muscle only occurs once the adult pattern of motor activity is established.

Prevalence of inadvertent hypothermia during the perioperative period: a quality assurance and performance improvement study

The inadvertent hypothermia that is often seen after anesthesia in a cool environment has been associated with delays in recovery from anesthesia and longer stays in the PACU. This quality assurance/performance improvement study was undertaken to determine the following: (1) the effectiveness of current interventions for preventing intraoperative hypothermia, (2) whether there were any apparent differences in effectiveness among the current methods for preventing intraoperative hypothermia, and (3) was intraoperative hypothermia associated with delays in discharge from the PACU. Data were completed on 502 patients. Despite longer surgical procedures, those patients treated intraoperatively with the Bair Hugger (Augustine Medical Inc, Eden Prairie, MN) were less likely to arrive in the PACU hypothermic than those who did not receive this treatment. Patients who arrived in the PACU hypothermic had longer PACU stays than patients who arrived normothermic. As a result of these findings, changes in nursing practice in the PACU and in the availability of the Bair Hugger in the operating rooms were made.

Serotonin promotes the differentiation of glutamate neurons in organotypic slice cultures of the developing cerebral cortex

The monoamines serotonin (5-HT), noradrenaline (NA), and dopamine (DA), which are present in the developing brain apparently before they assume their neurotransmitter functions, are regarded as strong candidates for a role in the maturation of the cerebral cortex. Here we sought to investigate their effects on the generation and differentiation of cortical cell types. Slice cultures, prepared from the cortices of embryonic day (E) 14, E16, and E19 rat fetuses, were kept in defined medium or in defined medium plus 5-HT for 7 d. E16 cortices were also exposed to NA or DA for the same period. At the end of this period, the proportions of the neuronal [glutamate (Glu)-, GABA-, calbindin-, calretinin-labeled], glial (GFAP), and neuroepithelial (nestin) cell types were estimated for all conditions. We found that in E16 cultures, application of 5-HT, but not of NA or DA, significantly increased the proportion of Glu-containing neurons without affecting the overall neuronal population or the proportions of any other cell types. A similar effect was observed in co-cultures of E16 cortex with slices through the midbrain raphe nuclei of E19 rats. The total amount of cortical Glu, as measured with HPLC, was also increased in these co-cultures. To investigate whether the effect of 5-HT was the result of changes in cell proliferation, we exposed slices to bromodeoxyuridine (BrdU) and found that the proportion of BrdU-labeled cells was similar in the 5-HT-treated and control slices. These results indicate that 5-HT promotes the differentiation of cortical Glu-containing neurons without affecting neuroepithelial cell proliferation.

Increase in nitric oxide synthase and NADPH-diaphorase in the adrenal gland of streptozotocin-diabetic Wistar rats and its prevention by ganglioside

Levels of nitric oxide synthase (NOS) and NADPH-diaphorase in adrenal glands of streptozotocin-diabetic rats of 8 and 12 weeks' duration compared with control rats were assessed with histo-chemical and biochemical techniques. Adrenal glands from streptozotocin-diabetic rats of 8 weeks' duration treated with ganglioside were examined also. In the adrenal medulla of 8-weeks- and 12-weeks-diabetic rats, NOS-immunoreactive nerve fibres were increased and decreased, respectively; additional NOS-immunoreactive and NADPH-diaphorase stained cells, which appeared to be cortical cells, were located in medulla and cortex compared with controls. Increased intensity in NADPH-diaphorase staining of the cortical cells of diabetic rats was observed also. Ganglioside treatment of the 8-weeks-diabetic rats prevented the diabetic-induced increase in NOS-immunoreactive nerve fibres. Also, it reduced most of the increase in the NOS-immunoreactive and NADPH-diaphorase stained cells and the intensity of NADPH-diaphorase staining of cortical cells. With biochemical assay, a significant increase in NOS activity was found in the adrenal glands from 8-weeks-diabetic rats, and this increase was reduced by ganglioside treatment in four out of six diabetic rats. In summary, streptozotocin-induced diabetes causes an initial increase in the levels of NOS and NADPH-diaphorase in the adrenal gland of rat, which was prevented by ganglioside treatment.

Effects of vitamin E deficiency on autonomic neuroeffector mechanisms in the rat caecum, vas deferens and urinary bladder

1. Modified sucrose-gap, standard organ-bath techniques and transmitter release studies were used to examine neuromuscular transmission in the caecum, vas deferens and urinary bladder in normal rats and in rats maintained for 12 months on a diet free of vitamin E. 2. In the caecum circular muscle, non-adrenergic, non-cholinergic inhibitory junction potentials were absent from 48 and 15% of preparations from vitamin E-deficient and control animals, respectively. Cholinergic excitatory junction potentials were absent from 83 and 8% of vitamin E-deficient and control preparations, respectively. Responses to applied noradrenaline (0.1-30 microM), alpha,beta-methylene ATP (3-100 microM) and acetylcholine (0.1-30 microM) were attenuated or absent in vitamin E-deficient tissues. Responses to applied KCl were similar in both groups. Release of [3H]noradrenaline or endogenous acetylcholine could not be evoked from vitamin E-deficient tissues. 3. In contrast, in isolated preparations of the vas deferens and urinary bladder, neuromuscular transmission by adrenergic, cholinergic and purinergic components were unaffected by long-term vitamin E deficiency. 4. In conclusion, vitamin E deficiency causes dysfunction of autonomic neuroeffector mechanisms in the smooth muscle of the rat caecum, at both a pre- and postjunctional level. The lesions in autonomic transmission mechanisms brought about by long-term vitamin E deficiency were found only in the caecum; no changes in sympathetic neuromuscular transmission were observed in the vas deferens, or in parasympathetic neuromuscular transmission in the urinary bladder.

Plasticity in the myenteric plexus of the rat ileum after long-term sympathectomy

To investigate the effect of chronic sympathectomy on the innervation of a tissue with an extensive intrinsic component, 1-week-old rat pups were treated with 50 mg/kg guanethidine for 3 weeks, a treatment shown to produce complete and long-lasting sympathectomy, and the ileum examined. Changes in the levels of noradrenaline, neuropeptide Y, calcitonin gene-related peptide, substance P and vasoactive intestinal polypeptide in the external muscle layers containing the myenteric plexus of the ileum were determined between 6 and 20 weeks of age. After sympathectomy, noradrenaline levels were initially depleted (3% of age-matched controls at 6 weeks, P < 0.001, and 18% of age-matched controls at 12 weeks, P < 0.001), but were not significantly reduced at 20 weeks (67% of age-matched controls). Such increases in noradrenaline content with time after sympathectomy did not occur in the mesenteric vein (levels in 20-week-old sympathectomized rats were 2% of the control values (P < 0.001). In the myenteric plexus, catecholamine fluorescent nerve fibers were seen in the 12-week-old sympathectomized rats, although tyrosine hydroxylase-immunoreactivity was absent. Guanethidine sympathectomy had no effect on the neuropeptide levels in 6-week-old rat ileum but there was a selective increase at 20 weeks; the levels of calcitonin gene-related peptide and substance P were increased (X3, P < 0.001 and X1.6, P < 0.05, respectively) while vasoactive intestinal polypeptide and neuropeptide Y levels were unchanged. Short-term sympathectomy (destruction of sympathetic nerve terminals by acute 6-hydroxydopamine treatment) had no affect on noradrenaline or peptide levels in this tissue.(ABSTRACT TRUNCATED AT 250 WORDS)

Conditions required for the measurement of nitric oxide synthase activity in a myenteric plexus/smooth muscle preparation from the rat ileum

Nitric oxide synthase (NOS) activity was measured, by the conversion of arginine to citrulline, in a preparation from the rat ileum consisting of the myenteric plexus and smooth muscle layers. A variety of incubating media were used in order to establish the optimal conditions required for the assay. NOS activity was present in the soluble fraction and was Ca(2+)- and calmodulin-dependent, characteristic of neuronal NOS. Exogenous Ca2+ was required for activity to be detectable but NOS activity progressively decreased with Ca2+ concentrations above 1.25 mM. Activity varied with arginine concentration, reaching saturation at 6 microM, and required the addition of the co-substrate NADPH. Endogenous levels of co-factors in the crude soluble fraction were not sufficient to maintain NOS activity. Omission of flavin adenine dinucleotide and tetrahydrobiopterin from the incubation medium reduced activity by 90%, and both co-factors had to be present for maximal activity to occur. These results emphasize the need to control assay conditions when measuring NOS activity in crude preparations from peripheral tissue.

Innervation of cerebral arteries by nerves containing 5-hydroxytryptamine and noradrenaline

Noradrenaline (NA)-containing nerves, mainly originating in the sympathetic superior cervical ganglia, supply large and small cerebral arteries. In large cerebral arteries, nerves containing serotonin (5-hydroxytryptamine, 5-HT) may represent neuronal uptake of circulating 5-HT by sympathetic nerves. 5-HT-containing nerves supplying small pial vessels probably have a central origin in the dorsal raphe nucleus. In most species, NA is a weak vasoconstrictor (alpha 1- or alpha 2-adrenoceptors), while 5-HT is a potent vasoconstrictor (5-HT2 or 5-HT1-like receptors) of large cerebral arteries. In contrast, both NA and 5-HT tend to cause vasodilatation in small pial vessels and arterioles. Adrenergic and serotonergic transmission can be modulated by pH, a range of putative neurotransmitters and neuromodulators, and by the endothelium. Sumatriptan, a 5-HT1-like receptor agonist, has been shown to be effective in the treatment of migraine. Changes in NA- or 5-HT-containing nerves and/or in the responses of cerebral vessels to NA and 5-HT have been observed in a variety of vascular disorders, including cerebral vasospasm following subarachnoid haemorrhage, hypertension, and atherosclerosis.

Effects of acrylamide on cotransmission in perivascular sympathetic and sensory nerves

The effects of chronic administration of acrylamide on sympathetic and sensory nerves were examined in the mesenteric artery of rabbits. The noradrenaline (NA) content of the artery was significantly decreased and the total contractile response to electrical field stimulation (4-64 Hz) markedly reduced in the acrylamide group. This was not due to an impairment of the contractility of the smooth muscle or to alterations in the postjunctional receptors. At 16 Hz, only the purinergic component of sympathetic cotransmission was significantly reduced by acrylamide. At 64 Hz, both the purinergic and the adrenergic components were significantly decreased. Field stimulation of the artery pretreated with guanethidine and precontracted with NA produced a frequency-dependent relaxation which was prevented by capsaicin and thus mediated by perivascular sensory nerves. In contrast to its effects on sympathetic cotransmission, acrylamide resulted in a trend, although not significant, towards increased responses at each frequency studied (2-16 Hz). 2-Methylthio-ATP (2Me-S-ATP) caused significantly greater relaxation following acrylamide treatment while vasodilator responses to calcitonin gene-related peptide and substance P were unchanged. It is concluded that, in addition to its known action in producing neuropathy in myelinated somatic motor and sensory nerves, acrylamide causes damage to unmyelinated perivascular sympathetic fibres. Purinergic mechanisms may be particularly susceptible to acrylamide since both the purinergic component of sympathetic vasoconstriction and the relaxation in response to 2Me-S-ATP were affected by acrylamide treatment.

Plasticity of autonomic nerves: differential effects of long-term guanethidine sympathectomy on the sensory innervation of the rat uterus during maturation

The sensory nerves, containing substance P and calcitonin gene-related peptide, and noradrenaline-containing sympathetic nerves of the rat uterus were analyzed following long-term sympathectomy with guanethidine in prepubertal (four weeks), young adult (eight weeks) and fully adult animals (18 weeks). Immunohistochemical and histochemical methods were used in association with nerve density measurements and biochemical assays. The main findings were as follows: (1) long-term guanethidine treatment completely abolished the noradrenergic innervation of the uterine horn and parametrial tissue and markedly reduced the tissue levels of noradrenaline in both regions at the three ages analysed; (2) in the uterine horn guanethidine treatment had no effect on the tissue levels of either calcitonin gene-related peptide or substance P or on the density of calcitonin gene-related peptide-containing nerves, at any of the three ages studied; (3) in the parametrial tissue increased levels of calcitonin gene-related peptide were observed at 8 and 18 weeks of age, together with a significant increase in the density of calcitonin gene-related peptide-containing nerves. Substance P levels showed a transient increase in this tissue at eight weeks. In conclusion, long-term sympathectomy with guanethidine resulted in an increase in calcitonin gene-related peptide and substance P in sensory nerves in the parametrial tissue, but not in the uterine horn. The changes in the parametrial tissue only occurred after puberty. It is suggested that sensory nerves in the uterine horn may be less responsive to sympathetic denervation since loss of sympathetic nerves occurs as part of a normal physiological process during pregnancy in this region.

Maturational changes in sympathetic and sensory innervation of the rat uterus: effects of neonatal capsaicin treatment

The plasticity of the sympathetic and sensory innervation of the rat uterus was examined, before and after puberty, in controls and in animals where primary sensory nerves had been destroyed by neonatal capsaicin treatment. Immunohistochemical and histochemical methods were used in association with nerve density measurements and biochemical assays. The main findings were as follows: (1) Puberty was associated with a marked increase in the weight of the uterine horn, uterine cervix and parametrial tissue. This was unaffected by capsaicin treatment. (2) The sympathetic innervation of the uterine horn and parametrial tissue was reduced following puberty as revealed by a decrease in the density of noradrenaline-containing nerves and a marked decrease in the tissue concentration of noradrenaline. Sympathetic nerves supplying the uterine cervix and the blood vessels of the uterus appeared to be unaffected by puberty. (3) In contrast, the sensory supply of the uterus by substance P and calcitonin gene-related peptide-containing nerves increased in parallel with uterine growth during puberty resulting in no change in nerve density and only a slight reduction in peptide concentration. (4) Neonatal capsaicin treatment caused a long-lasting depletion of substance P- and calcitonin gene-related peptide-containing nerves. In the uterine horn and parametrial tissue, capsaicin-resistant calcitonin gene-related peptide, but not substance P, still increased with tissue weight during puberty, indeed, in the uterine horn, the relative increase was greater than in controls. (5) Sensory denervation resulted in an increase in the non-vascular sympathetic supply of the uterus, although there was a regional variation in the time course of the response. Perivascular sympathetic nerves were unaffected by capsaicin treatment. The pattern of change in non-vascular noradrenaline-containing nerves associated with puberty was similar in nature to controls. Thus, there is considerable plasticity in the innervation of the uterus both during puberty and following sensory denervation. A complex pattern of change occurs with differential responses in vascular and nonvascular nerves and in different regions of the uterus. Such differences may be due in part to the different origins of individual nerve populations and/or to their relative sensitivities to sex hormones.

Innervation of normal human sural and optic nerves by noradrenaline- and peptide-containing nervi vasorum and nervorum: effect of diabetes and alcoholism

Histochemical, immunohistochemical and neurochemical techniques were used to examine the innervation of epineurial nerve sheaths and fascicular nerve bundles of human sural and optic nerves from controls and patients with peripheral neuropathy due to diabetes or alcoholism. The normal distribution of autonomic nerves in both nerve trunk sheaths consisted of a dense innervation by noradrenaline (NA)-containing nerves of the vasa nervorum, together with some fibres in the nervi nervorum. Intrafascicular NA-containing nerves were only present in the sural nerve. Vasoactive intestinal polypeptide (VIP)- and neuropeptide Y (NPY)-containing nerves also innervated the vasa nervorum and nervi nervorum of the nerve sheaths, although their density was considerably less. Substance P (SP)-containing nerves were sparse and primarily intrafascicular. Neurochemical assays for NA, VIP, NPY and SP in fascicular and epineurial preparations from the sural and optic nerves confirmed the light microscopical observations. Post mortem delay significantly affected the NA levels in the sural nerve but not in the optic nerve while the NA fascicular/epineurial ratio for the sural nerve was independent of this factor. Age, sex and the presence of alcohol at time of death had no effect on transmitter levels in normal sural nerves. In the optic nerve fascicles NA levels were higher in females than in males. In patients with peripheral neuropathy there was a significant reduction in the SP fascicular/epineurial ratio in both the optic nerve, which was histologically normal, and in the sural nerve, where there was evidence of neuropathy. The NA fascicular/epineurial ratio was also significantly reduced in the sural nerve from patients with peripheral neuropathy with a possible greater effect in diabetes.(ABSTRACT TRUNCATED AT 250 WORDS)

Differential regulation of tyrosine hydroxylase protein and activity in rabbit sympathetic neurones after long-term cold exposure: altered responses in ageing

The aim of this study was to investigate the response of sympathetic neurones to prolonged neural stimulation, using cold exposure as a non-invasive experimental paradigm. We examined the effects of prolonged (8 days and 4 wk) cold exposure on tyrosine hydroxylase (TH) protein and activity and neuropeptide Y (NPY) levels in sympathetic neurones of the superior cervical ganglion (SCG), together with NPY levels in the ear artery from young and aged rabbits. The main findings were as follows. In young rabbits, TH levels and TH activity were differentially regulated in response to prolonged cold exposure. TH levels rose whilst TH activity tended to decline. Decentralization of SCG from young animals before cold exposure abolished the rise in TH levels. TH activity in SCG from young rabbits was reduced by decentralization whilst cold exposure resulted in an increase in TH activity. Thus, TH activity was induced in the SCG in the absence of pre-ganglionic input, demonstrating a non-synaptic regulatory mechanism. In old rabbits, cold-induced changes were either delayed or failed to occur, indicating that the responses of sympathetic neurones to cold stress are impaired in old age.

Postnatal development of noradrenaline-containing nerves of the rat uterus

The postnatal development of noradrenaline (NA)-containing nerves of the rat uterus and its associated blood vessels was investigated using histochemical and biochemical methods. These studies were carried out in conjunction with examination of the morphology of the uterus and the density of blood vessels at the prepubertal, peripubertal and adult stages. It was demonstrated that: (1) the rat uterus is innervated at birth; (2) the innervation of blood vessels develops earlier than that of the myometrium and the density of NA-containing perivascular nerves is not affected by puberty; (3) between birth and day 30 (prepubertal) there was a progressive increase in the innervation of the myometrium which was accompanied by a progressive increase in the total NA content of the organ; (4) at the first oestrus there was a marked increase in the weight of the uterus and isolated myometrial and parametrial tissue. Both muscle cell size and number were also increased. The density of myometrial innervation by NA-containing nerves was markedly reduced, although the total NA content did not change at this stage. This indicates a 'dilution' of myometrial NA-containing nerves in a greater amount of non-neuronal tissue; and (5) between the peripubertal and adult stages there was a further increase in uterine weight together with an increase in the number of smooth muscle cells and a reduction in the density of myometrial NA-containing nerves. Although the density of perivascular nerves was unaffected by puberty, the number of blood vessels supplying the uterus increased during the transition to the adult stage. This was reflected by a significant increase in the total NA content of the uterine horn and of isolated myometrial and parametrial preparations.

Guanethidine sympathectomy of mature rats leads to increases in calcitonin gene-related peptide and vasoactive intestinal polypeptide-containing nerves

Changes in the innervation of the heart (right atrium), mesenteric blood vessels, vas deferens and superior cervical ganglia have been examined following long-term sympathectomy of the mature rat. Patterns of innervation were investigated by histochemical and immunohistochemical techniques, while levels of noradrenaline and neuropeptides were measured by neurochemical assays. Large doses of guanethidine (80 mg/kg) were given daily for four weeks to 12-14 week-old male rats which were killed at 18-20 weeks of age. Catecholamine-containing nerves were severely depleted or absent in all tissues, together with a reduction in noradrenaline content. Neuropeptide Y levels were depleted by 97% in vas deferens, 78% in mesenteric vein and 50% in right atrium and superior cervical ganglion. Increases in levels of calcitonin gene-related peptide were seen in the mesenteric vein (up seven-fold), superior cervical ganglia (up 11-fold) and vas deferens (prostatic portion up three-fold), which were also evident by assessment of immunolabelling of nerve fibres. Calcitonin gene-related peptide levels were not increased in the right atrium. In addition, an increase in vasoactive intestinal polypeptide-immunoreactive nerve fibre density was seen in the mesenteric artery and vas deferens, although no significant differences were observed in assays of vasoactive intestinal peptide levels in any tissue. No changes were seen in the innervation of any of the tissues by substance P-immunoreactive nerve fibres either by immunohistochemical or immunochemical assay assessment. This study indicates that there are selective changes in the mature nervous system in response to the loss of sympathetic nerves. Differences between these changes and the response of the developing nervous system to long-term sympathectomy are discussed.

Changes in sympathetic and endothelium-mediated responses in the rabbit central ear artery after acrylamide treatment

The effect of acrylamide intoxication on the innervation and local control of the rabbit central ear artery was investigated. There was no difference in the noradrenaline, neuropeptide Y and calcitonin gene-related peptide tissue content between control and experimental animals. There was, however, a slight reduction in catecholamine histofluorescence. Although the contractile efficiency of the rabbit central ear artery as measured by responses to potassium chloride was unchanged, nerve-mediated contractile responses were significantly attenuated in acrylamide-treated animals. Contractile responses induced by exogenous alpha,beta-methylene ATP were markedly increased after acrylamide treatment, in contrast to contractions induced by exogenous noradrenaline which were attenuated at maximal concentrations. Modulatory effects of nerve-mediated contractile responses by neuropeptide Y were unaffected by acrylamide intoxication. It therefore appears that acrylamide intoxication damages sympathetic cotransmission, perhaps with preferential action on the purinergic component. Endothelium-dependent relaxant responses to acetylcholine and substance P were attenuated in acrylamide-treated animals, whereas relaxant responses mediated by calcitonin gene-related peptide (endothelium independent) were unaffected. The question of whether the damage to the endothelial cell action is a primary effect, or a secondary consequence of sympathetic nerve damage, is discussed.

Neuropeptide Y in non-sympathetic nerves of the rat: changes during maturation but not after guanethidine sympathectomy

Non-sympathetic neuropeptide Y-containing nerves were demonstrated by their persistence after destruction of sympathetic nerve terminals by acute 6-hydroxydopamine treatment for 48 h. In order to examine whether these neuropeptide Y-containing nerves reinnervate tissues following the loss of sympathetic nerves we administered guanethidine sulphate to one-week-old rat pups for three weeks to produce a complete and long-lasting sympathectomy and we monitored the innervation of the superior cervical ganglion, mesenteric vein, vas deferens and urinary bladder by noradrenaline- and neuropeptide Y-containing nerves two and 16 weeks later (assay and histochemical observations). By two weeks the reduction in neuropeptide Y content of tissues was similar to the reduction after acute sympathectomy with 6-hydroxydopamine treatment, indicating that there was no early reinnervation by non-sympathetic neuropeptide Y-containing nerve fibres at a time when sensory transmitters increase. Furthermore, there was no reinnervation by neuropeptide Y-containing nerve fibres by the time these sympathectomized animals had reached maturity, 16 weeks after cessation of treatment. Neuropeptide Y levels increased in the superior cervical ganglion with normal maturation but decreased in the prostatic end of the vas deferens. A non-sympathetic source of neuropeptide Y demonstrated in the immature rat vas deferens was no longer evident in the mature animal.

Sympathetic neurotransmission in the rabbit isolated central ear artery is affected as early as one week following a single dose of X-irradiation

1. The short-term effect of a single dose of 4500 rad X-irradiation on sympathetic neurotransmission (involving both noradrenergic and purinergic components) was assessed in the rabbit central ear artery, 1, 4 and 6 weeks post-irradiation. 2. Neurally mediated contractions were reduced as early as 1 week post-irradiation, with responses to lower frequency stimulation being initially most affected. This suggest that the purinergic component of the contractile response is affected earlier than the adrenergic component. 3. There was no change in the amplitude or sensitivity of treated preparations to the cumulative application of noradrenaline when compared with untreated preparations. In contrast, contractions to alpha, beta-methylene ATP (1 microM), a P2-purinoceptor agonist, were significantly increased at 4 and 6 weeks post-irradiation, although not at 1 week post-irradiation. 4. There were no apparent changes in the pattern of catecholamine fluorescence as a result of irradiation. However, the tissue content of noradrenaline was significantly reduced 6 weeks post-irradiation when compared with control preparations. 5. It is concluded that damage to sympathetic cotransmission is one of the early effects of irradiation, with initial impairment predominantly of the purinergic component.

Neuropeptide immunoreactivity and choline acetyltransferase activity in the mouse urinary bladder following inoculation with Semliki Forest Virus

The effect of Semliki Forest Virus, a known central demyelinating agent and a proposed model for multiple sclerosis, on the innervation of the mouse urinary bladder has been examined 3, 6, 9 and 12 weeks after inoculation. Three weeks after Semliki Forest Virus inoculation, vasoactive intestinal polypeptide content of the bladder was reduced and the density of vasoactive intestinal polypeptide-immunoreactive nerves was decreased in the smooth muscle, but not in the mucosa. Choline acetyltransferase activity and neuropeptide Y and substance P content was normal, as was the pattern of innervation by acetylcholinesterase-containing and neuropeptide Y- and substance P-immunoreactive nerve fibres. Six weeks after Semliki Forest Virus inoculation, the choline acetyltransferase activity was significantly reduced. Between 6 and 9 weeks the level of vasoactive intestinal polypeptide in the bladder of Semliki Forest Virus-infected mice significantly increased, so that at 9 weeks it was higher than the control value. However, by 12 weeks both choline acetyltransferase activity and vasoactive intestinal polypeptide content were normal. At this time, the substantial age-related increase in substance P content of the bladder was more pronounced in the Semliki Forest Virus-treated animals. Thus there are transitory changes in the innervation of the mouse bladder by vasoactive intestinal polypeptide-containing and cholinergic nerve fibres after exposure to a central demyelinating agent which may reflect changes in bladder dysfunction seen in multiple sclerosis patients.