Seaweed biogeochemistry: Global assessment of C:N and C:P ratios and implications for ocean afforestation.

Algal carbon-to-nitrogen (C:N) and carbon-to-phosphorus (C:P) ratios are fundamental for understanding many oceanic biogeochemical processes, such as nutrient flux and climate regulation. We synthesized literature data (444 species, >400 locations) and collected original samples from Tasmania, Australia (51 species, 10 locations) to update the global ratios of seaweed carbon-to-nitrogen (C:N) and carbon-to-phosphorus (C:P). The updated global mean molar ratio for seaweed C:N is 20 (ranging from 6 to 123) and for C:P is 801 (ranging from 76 to 4102). The C:N and C:P ratios were significantly influenced by seawater inorganic nutrient concentrations and seasonality. Additionally, C:N ratios varied by phyla. Brown seaweeds (Ochrophyta, Phaeophyceae) had the highest mean C:N of 27.5 (range: 7.6-122.5), followed by green seaweeds (Chlorophyta) of 17.8 (6.2-54.3) and red seaweeds (Rhodophyta) of 14.8 (5.6-77.6). We used the updated C:N and C:P values to compare seaweed tissue stoichiometry with the most recently reported values for plankton community stoichiometry. Our results show that seaweeds have on average 2.8 and 4.0 times higher C:N and C:P than phytoplankton, indicating seaweeds can assimilate more carbon in their biomass for a given amount of nutrient resource. The stoichiometric comparison presented herein is central to the discourse on ocean afforestation (the deliberate replacement of phytoplankton with seaweeds to enhance the ocean biological carbon sink) by contributing to the understanding of the impact of nutrient reallocation from phytoplankton to seaweeds under large-scale seaweed cultivation.

Less is more: balancing noise reduction and data retention in fMRI with data-driven scrubbing.

Functional MRI (fMRI) data may be contaminated by artifacts arising from a myriad of sources, including subject head motion, respiration, heartbeat, scanner drift, and thermal noise. These artifacts cause deviations from common distributional assumptions, introduce spatial and temporal outliers, and reduce the signal-to-noise ratio of the data-all of which can have negative consequences for the accuracy and power of downstream statistical analysis. Scrubbing is a technique for excluding fMRI volumes thought to be contaminated by artifacts and generally comes in two flavors. Motion scrubbing based on subject head motion-derived measures is popular but suffers from a number of drawbacks, among them the need to choose a threshold, a lack of generalizability to multiband acquisitions, and high rates of censoring of individual volumes and entire subjects. Alternatively, data-driven scrubbing methods like DVARS are based on observed noise in the processed fMRI timeseries and may avoid some of these issues. Here we propose "projection scrubbing", a novel data-driven scrubbing method based on a statistical outlier detection framework and strategic dimension reduction, including independent component analysis (ICA), to isolate artifactual variation. We undertake a comprehensive comparison of motion scrubbing with data-driven projection scrubbing and DVARS. We argue that an appropriate metric for the success of scrubbing is maximal data retention subject to reasonable performance on typical benchmarks such as the validity, reliability, and identifiability of functional connectivity. We find that stringent motion scrubbing yields worsened validity, worsened reliability, and produced small improvements to fingerprinting. Meanwhile, data-driven scrubbing methods tend to yield greater improvements to fingerprinting while not generally worsening validity or reliability. Importantly, however, data-driven scrubbing excludes a fraction of the number of volumes or entire sessions compared to motion scrubbing. The ability of data-driven fMRI scrubbing to improve data retention without negatively impacting the quality of downstream analysis has major implications for sample sizes in population neuroscience research.

ciftiTools: A package for reading, writing, visualizing, and manipulating CIFTI files in R.

There is significant interest in adopting surface- and grayordinate-based analysis of MR data for a number of reasons, including improved whole-cortex visualization, the ability to perform surface smoothing to avoid issues associated with volumetric smoothing, improved inter-subject alignment, and reduced dimensionality. The CIFTI grayordinate file format introduced by the Human Connectome Project further advances grayordinate-based analysis by combining gray matter data from the left and right cortical hemispheres with gray matter data from the subcortex and cerebellum into a single file. Analyses performed in grayordinate space are well-suited to leverage information shared across the brain and across subjects through both traditional analysis techniques and more advanced statistical methods, including Bayesian methods. The R statistical environment facilitates use of advanced statistical techniques, yet little support for grayordinates analysis has been previously available in R. Indeed, few comprehensive programmatic tools for working with CIFTI files have been available in any language. Here, we present the ciftiTools R package, which provides a unified environment for reading, writing, visualizing, and manipulating CIFTI files and related data formats. We illustrate ciftiTools' convenient and user-friendly suite of tools for working with grayordinates and surface geometry data in R, and we describe how ciftiTools is being utilized to advance the statistical analysis of grayordinate-based functional MRI data.

Sources of residual autocorrelation in multiband task fMRI and strategies for effective mitigation.

Introduction: Analysis of task fMRI studies is typically based on using ordinary least squares within a voxel- or vertex-wise linear regression framework known as the general linear model. This use produces estimates and standard errors of the regression coefficients representing amplitudes of task-induced activations. To produce valid statistical inferences, several key statistical assumptions must be met, including that of independent residuals. Since task fMRI residuals often exhibit temporal autocorrelation, it is common practice to perform "prewhitening" to mitigate that dependence. Prewhitening involves estimating the residual correlation structure and then applying a filter to induce residual temporal independence. While theoretically straightforward, a major challenge in prewhitening for fMRI data is accurately estimating the residual autocorrelation at each voxel or vertex of the brain. Assuming a global model for autocorrelation, which is the default in several standard fMRI software tools, may under- or over-whiten in certain areas and produce differential false positive control across the brain. The increasing popularity of multiband acquisitions with faster temporal resolution increases the challenge of effective prewhitening because more complex models are required to accurately capture the strength and structure of autocorrelation. These issues are becoming more critical now because of a trend toward subject-level analysis and inference. In group-average or group-difference analyses, the within-subject residual correlation structure is accounted for implicitly, so inadequate prewhitening is of little real consequence. For individual subject inference, however, accurate prewhitening is crucial to avoid inflated or spatially variable false positive rates. Methods: In this paper, we first thoroughly examine the patterns, sources and strength of residual autocorrelation in multiband task fMRI data. Second, we evaluate the ability of different autoregressive (AR) model-based prewhitening strategies to effectively mitigate autocorrelation and control false positives. We consider two main factors: the choice of AR model order and the level of spatial regularization of AR model coefficients, ranging from local smoothing to global averaging. We also consider determining the AR model order optimally at every vertex, but we do not observe an additional benefit of this over the use of higher-order AR models (e.g. (AR(6)). To overcome the computational challenge associated with spatially variable prewhitening, we developed a computationally efficient R implementation using parallelization and fast C++ backend code. This implementation is included in the open source R package BayesfMRI. Results: We find that residual autocorrelation exhibits marked spatial variance across the cortex and is influenced by many factors including the task being performed, the specific acquisition protocol, mis-modeling of the hemodynamic response function, unmodeled noise due to subject head motion, and systematic individual differences. We also find that local regularization is much more effective than global averaging at mitigating autocorrelation. While increasing the AR model order is also helpful, it has a lesser effect than allowing AR coefficients to vary spatially. We find that prewhitening with an AR(6) model with local regularization is effective at reducing or even eliminating autocorrelation and controlling false positives. Conclusion: Our analysis revealed dramatic spatial differences in autocorrelation across the cortex. This spatial topology is unique to each session, being influenced by the task being performed, the acquisition technique, various modeling choices, and individual differences. If not accounted for, these differences will result in differential false positive control and power across the cortex and across subjects.

Sequential Magnetic Resonance Imaging Reveals Individual Level Deformities of Vertebrae and Discs in the Growing Scoliotic Spine.

STUDY DESIGN: The aim of this study was to measure contributions of individual vertebra and disc wedging to coronal Cobb angle in the growing scoliotic spine using sequential magnetic resonance imaging (MRI). Clinically, the Cobb angle measures the overall curve in the coronal plane but does not measure individual vertebra and disc wedging. It was hypothesized that patients whose deformity progresses will have different patterns of coronal wedging in vertebrae and discs to those of patients whose deformities remain stable. METHODS: A group of adolescent idiopathic scoliosis (AIS) patients each received two to four MRI scans (spaced 3-12 months apart). The coronal plane wedge angles of each vertebra and disc in the major curve were measured for each scan, and the proportions and patterns of wedging in vertebrae and discs were analyzed for subgroups of patients whose spinal deformity did and did not progress during the study period. RESULTS: Sixteen patients were included in the study; the mean patient age was 12.9 years (standard deviation 1.7 years). All patients were classified as right-sided major thoracic Lenke Type 1 curves (9 type 1A, 4 type 1B, and 3 type 1C). Cobb angle progression of ≥5° between scans was seen in 56% of patients. Although there were measurable changes in the wedging of individual vertebrae and discs in all patients, there was no consistent pattern of deformity progression between patients who progressed and those who did not. The patterns of progression found in this study did not support the hypothesis of wedging commencing in the discs and then transferring to the vertebrae. CONCLUSION: Sequential MRI data showed complex patterns of deformity progression. Changes to the wedging of individual vertebrae and discs may occur in patients who have no increase in Cobb angle; therefore, the Cobb method alone may be insufficient to capture the complex mechanisms of deformity progression.

Vascular endothelial growth factor protects post-ganglionic sympathetic neurones from the detrimental effects of hydrogen peroxide by increasing catalase.

AIM: Vascular production of hydrogen peroxide (H(2)O(2)) is implicated in the development and progression of vascular disease. Hydrogen peroxide also promotes neuronal degeneration, which suggests that vascular H(2)O(2) would promote degeneration of perivascular sympathetic nerves. Vascular cells also produce vascular endothelial growth factor (VEGF), which could protect perivascular nerves from the detrimental effects of H(2)O(2) . The aim of this study was to test these hypotheses. METHODS: The effects of H(2)O(2) and VEGF on neuronal survival and noradrenaline uptake were studied in cultures of rat post-ganglionic sympathetic neurones. Western analyses of catalase and growth associated protein 43 were performed and reactive oxygen species (ROS) were measured using the fluorescent indicator 5-(and-6)-chloromethyl-2'7'-dichlorodihydrofluorescein diacetate, acetyl ester. RESULTS: Hydrogen peroxide (30 µm) decreased the survival of post-ganglionic sympathetic neurones (57.8 ± 4.8% of control) and decreased noradrenaline uptake into the neurones (14 ± 6% of control). Hyperglycaemia, which is known to increase H(2)O(2), also decreased survival (31.4 ± 12% of control) and noradrenaline uptake (42 ± 18.4% of control). VEGF reduced the effects of H(2)O(2) (94.3 ± 12% of control) and hyperglycaemia (83.5 ± 23.6% of control) on survival. VEGF increased catalase, a primary determinant of intracellular concentrations of H(2)O(2) , and decreased H(2)O(2) -induced increases in ROS. CONCLUSION: These results indicate that VEGF protects post-ganglionic sympathetic neurones from the detrimental effects of H(2)O(2). Our data suggest that an increase in catalase is the mechanisms underlying this neuroprotection.

Pancreatic arteriovenous malformation: a case report and literature review.

Most pancreatic arteriovenous malformations (PAVM) present due to gastrointestinal bleeding or abdominal pain, but these patients may be asymptomatic. Increased portal vein flow from these malformations can lead to portal hypertension and gastrointestinal bleeding. Diagnosis is often made by imaging, and early diagnosis has led to successful surgical resection or percutaneous embolization. We report a patient with PAVM, diagnosed by CT and angiography, who has remained asymptomatic for 2 years without treatment.

Effects of an oral health education program for pregnant women.

PURPOSE: The purpose of this study was to evaluate the gain in knowledge of oral health after education to pregnant women on dental anticipatory guidance and to determine how much of this information pregnant women retain over time. METHODS: The study consisted of 40 pregnant women. Inclusion criteria included: (1) between the ages of 21-40; (2) in 12-40th week of pregnancy; and (3) spoke English. During the first visit, all subjects were asked to complete a pre-test (24 questions), watch a ten minute presentation and complete the post-test (24 questions). During the second visit (4 weeks/1 month after the first visit), all subjects were asked to complete the follow-up test (24 questions). RESULTS: All of the tests (pre, post and follow-up) were scored and used to determine the changes in knowledge of the pregnant women after the presentation. The mean age for all 40 pregnant women was 26.88 (SD +/- 4.3) years and the mean number of weeks pregnant was 25.2 at the first visit. The mean overall correct scores for the pre-test was 12.9 (53.75%), post-test was 20.9 (87.08%) and follow-up test was 20.17 (84.05%). These overall scores show an improvement of 8 (33.33%, p<0.05) questions correct from the first to second test, and a digression of 0.73 (3.08%) questions correct from the second to third test. CONCLUSIONS: These observations indicate that in this study population pregnant women's knowledge improved after a presentation on dental anticipatory guidance. These observations also indicate that after four weeks, pregnant women were able to retain most of the information, as only a slight digression in overall scores was noticed from the follow-up test to the post-test.

Effect of novel negative allosteric modulators of neuronal nicotinic receptors on cells expressing native and recombinant nicotinic receptors: implications for drug discovery.

Allosteric modulation of nAChRs is considered to be one of the most promising approaches for drug design targeting nicotinic acetylcholine receptors (nAChRs). We have reported previously on the pharmacological activity of several compounds that seem to act noncompetitively to inhibit the activation of alpha3beta4(*) nAChRs. In this study, the effects of 51 structurally similar molecules on native and recombinant alpha3beta4 nAChRs are characterized. These 51 molecules inhibited adrenal neurosecretion activated via stimulation of native alpha3beta4(*) nAChR, with IC(50) values ranging from 0.4 to 13.0 microM. Using cells expressing recombinant alpha3beta4 nAChRs, these molecules inhibited calcium accumulation (a more direct assay to establish nAChR activity), with IC(50) values ranging from 0.7 to 38.2 microM. Radiolabeled nAChR binding studies to orthosteric sites showed no inhibitory activity on either native or recombinant nAChRs. Correlation analyses of the data from both functional assays suggested additional, non-nAChR activity of the molecules. To test this hypothesis, the effects of the drugs on neurosecretion stimulated through non-nAChR mechanisms were investigated; inhibitory effects ranged from no inhibition to 95% inhibition at concentrations of 10 microM. Correlation analyses of the functional data confirmed this hypothesis. Several of the molecules (24/51) increased agonist binding to native nAChRs, supporting allosteric interactions with nAChRs. Computational modeling and blind docking identified a binding site for our negative allosteric modulators near the orthosteric binding site of the receptor. In summary, this study identified several molecules for potential development as negative allosteric modulators and documented the importance of multiple screening assays for nAChR drug discovery.

A facile synthesis of a polyhydroxylated 2-azabicyclo[3.2.1]octane.

Synthetic or natural aza-sugars have shown promise as a therapeutic approach to a variety of disease states by acting as transition state mimics to sugar processing enzymes. Although the synthesis of functionalized bicyclo[3.2.1]octanes has been reported, the procedures are relatively long and low yielding. Herein, we report the facile synthesis of polyhydroxylated 2-azabicyclo[3.2.1]octane that can be selectively functionalized.

Prevalence and denial of sexual abuse in a male psychiatric inpatient population.

While the link between sexual abuse and psychiatric morbidity is well established, there are only a few studies that have investigated the prevalence of sexual abuse in male psychiatric populations and these studies have typically employed designs that ignore methodological issues specific to male sexual abuse. The present study aims to contribute to this research using as methodologically sound approach as possible. Seventy-four male inpatients were interviewed using a questionnaire (J. N. Briere, 1992) about childhood sexual experiences. Approximately one third reported incidents that met this study's criteria for sexual abuse. Many of these men did not label such experiences as "sexual abuse." The results suggest that mental health professionals need to be aware that many of their male patients may have a history of sexual abuse and that potential minimization or denial of it is a barrier to disclosure.

Analysis of anabolic steroids in the horse: development of a generic ELISA for the screening of 17alpha-alkyl anabolic steroid metabolites.

Due to the potential for misuse of a wide range of anabolic steroids in horse racing, a screening test to detect multiple compounds, via a common class of metabolites, would be a valuable forensic tool. An enzyme-linked immunosorbent assay (ELISA) has been developed to detect 17alpha-alkyl anabolic steroid metabolites in equine urine. 16beta-Hydroxymestanolone (16beta,17beta-dihydroxy-17alpha-methyl-5alpha-androstan-3-one) was synthesised in six steps from commercially available epiandrosterone (3beta-hydroxy-5alpha-androstan-17-one). Polyclonal antibodies were raised in sheep, employing mestanolone (17beta-hydroxy-17alpha-methyl-5alpha-androstan-3-one) or 16beta-hydroxymestanolone conjugated to human serum albumin, via a 3-carboxymethyloxime linker, as antigens. Antibody cross-reactivities were determined by assessing the ability of a library of 54 representative steroids to competitively bind the antibodies. Antibodies raised against 16beta-hydroxymestanolone showed excellent cross-reactivities for all of the 16beta,17beta-dihydroxy-17alpha-methyl steroids analysed and an ELISA has been developed to detect these steroid metabolites. Using this 16beta-hydroxymestanolone assay, urine samples from horses administered with stanozolol (17alpha-methyl-pyrazolo[4',3':2,3]-5alpha-androstan-17beta-ol), were analysed raw, following beta-glucuronidase hydrolysis, and following solid-phase extraction (SPE) procedures. The suppressed absorbances observed were consistent with detection of the metabolite 16beta-hydroxystanozolol. Positive screening results were confirmed by comparison with standard LCMS analyses. Antibodies raised against mestanolone were also used to develop an ELISA and this was used to detect metabolites retaining the parent D-ring structure following methandriol (17alpha-methylandrost-5-ene-3beta,17beta-diol) administration. The ELISA methods developed have application as primary screening tools for detection of new and known anabolic steroid metabolites.

Detection of stanozolol and its metabolites in equine urine by liquid chromatography-electrospray ionization ion trap mass spectrometry.

The equine phase I and phase II metabolism of the synthetic anabolic steroid stanozolol was investigated following its administration by intramuscular injection to a thoroughbred gelding. The major phase I biotransformations were hydroxylation at C16 and one other site, while phase II metabolism in the form of sulfate and beta-glucuronide conjugation was extensive. An analytical procedure was developed for the detection of stanozolol and its metabolites in equine urine using solid phase extraction, acid solvolysis of phase II conjugates and analysis by positive ion electrospray ionization ion trap LC-MS.

Concurrent and adjuvant chemotherapy for nasopharyngeal carcinoma: a factorial study.

PURPOSE: To study the efficacy of concurrent chemoradiotherapy (CRT) and adjuvant chemotherapy (AC) for nasopharyngeal carcinoma (NPC). PATIENTS AND METHODS: Patients with Ho's stage T3 or N2/N3 NPC or neck node > or = 4 cm were eligible. Patients were randomly assigned to have radiotherapy (RT) or CRT with uracil and tegafur and to have AC or no AC after RT/CRT. AC comprised alternating cisplatin, fluorouracil, vincristine, bleomycin, and methotrexate for six cycles. There were four treatment groups: A, RT; B, CRT; C, RT and AC; D, CRT and AC. For CRT versus RT, groups B and D were compared with groups A and C. For AC versus no AC, groups C and D were compared with groups A and B. RESULTS: Three-year failure-free survival (FFS) and overall survival (OS) for CRT versus RT were 69.3% versus 57.8% and 86.5% versus 76.8%, respectively (P =.14 and.06; n = 110 v 109). Distant metastases rate (DMR) was significantly reduced with CRT (14.8% v 29.4%; P =.026). Locoregional failure rates (LRFR) were similar (20% v 27.6%; P =.39). Three-year FFS and OS for AC versus no AC were 62.5% versus 65% and 80.4% versus 83.1%, respectively (P =.83 and.69; n = 111 v 108). DMR and LRFR were not reduced with AC (P =.34 and.15, respectively). Cox model showed CRT to be a favorable prognostic factor for OS (hazard ratio, 0.42; P =.009). CONCLUSION: An improvement in OS with CRT was observed but did not achieve statistical significance. The improvement seemed to be associated with a significant reduction in DMR. AC did not improve outcome.

Pharmacological evaluation of (S)-8-[123I]iodobretazenil: a radioligand for in vivo studies of central benzodiazepine receptors.

In vitro studies on cortical membranes indicated (S)-8-[(123)I]iodobretazenil bound saturably to a single population of binding sites (B(max) = 2.33 pmol/mg protein) with a dissociation constant K(d) = 1.9 nM. (R)-8-[(123)I]Iodobretazenil displayed only non-specific binding. In vivo biodistribution of (S)-8-[(123)I]iodobretazenil in rats indicated high accumulation in regions of high BZR density. Radioactivity was blocked by preadministration with iodobretazenil and flumazenil, while non-BZR drugs had no effect on the uptake of activity in any brain region. (S)-8-[(123)I]Iodobretazenil uptake was saturable in a dose dependent manner (ID(50) = 0.13 mg/kg) in all brain regions. With the (R)-enantiomer no specific uptake was observed. Metabolite studies at 1-3 h p.i. indicated that greater than 95% of activity extracted from brain tissue corresponded to unchanged radiotracer while that in plasma was over 70%. (S)-8-[(123)I]Iodobretazenil potently and selectively labels BZR in vivo and deserves further investigation as a possible SPECT radiotracer.

Mining the Chemical Abstracts database with pharmacophore-based queries.

A method is described to convert 3D patterns of pharmacophoric groups into 2D queries for molecular substructure searches of the Chemical Abstracts database with SciFinder Scholar. The results of such searches and the options for refinement of the hit lists are presented using a rigid tetrahydroisoquinoline-carbazole (IQC) hybrid molecule fitted onto previously developed pharmacophores for subtype-selective alpha1-adrenergic receptor antagonists as an example. The compounds retrieved were further analysed by limiting their physical properties to 'drug-like' ranges and by enumerating the ring skeletons they contain. Selected ring skeletons were evaluated by fitting them on to the original pharmacophores. Several structurally novel rigid ring skeletons were found with this new database mining technique which are potentially useful as leads in the design of alpha1B selective adrenergic receptor antagonists.

PC12 cells stimulate vascular smooth muscle growth.

Sympathetic nerves stimulate vascular growth. The mechanisms underlying this stimulation have not been fully elucidated. PC12 cells and cultures of vascular smooth muscle were used to study sympathetic stimulation of vascular smooth muscle growth. Media conditioned by undifferentiated and differentiated PC12 cells stimulated the growth of vascular smooth muscle (446 +/- 47%). Differentiated PC12 cells produced more growth-stimulatory activity (61.5 +/- 9.6 per 10(6) cells) than undifferentiated PC12 cells (28.5 +/- 8.8 per 10(6) cells). PC12 stimulation of vascular smooth muscle growth was not inhibited by adrenergic receptor antagonists but was reduced by an endothelin antagonist, suramin, and an antibody that neutralized the activity of platelet-derived growth factor. These data suggest that endothelin and platelet-derived growth factor, but not catecholamines, play a role in sympathetic stimulation of vascular smooth muscle growth.

Endothelial cell-specific knockout of connexin 43 causes hypotension and bradycardia in mice.

Connexin 43 (Cx43) is a protein expressed in a variety of mammalian tissues. However, the lack of specific blockers and the absence of known genetic mutants have hampered the investigation of the function of this protein. Cx43-null mice die shortly after birth, thus preventing functional studies in vivo. Here, we report the generation and characterization of a vascular endothelial cell-specific deletion of the Cx43 gene (VEC Cx43 KO) in mice by using the loxP/Cre system. Using homologous recombination, a mouse line was created carrying loxP sites flanking exon 2 of the Cx43 gene ("floxed" mice). To produce cell specific deletion of the Cx43 gene, these mice were crossed with animals from a line carrying the Tie 2-Cre transgene. The homozygous VEC Cx43 KO mice survived to maturity. However, they were hypotensive and bradycardic when compared with heterozygous VEC Cx43 KO mice, or to the floxed Cx43 gene mice. The hypotension was associated with marked elevation of plasma nitric oxide (NO) levels as well as elevated plasma angiotensin (Ang) I and II. We hypothesize that endothelial cell Cx43 plays a key role in the formation and/or action of NO, and that the elevation of Ang II is a secondary event. The specific cellular basis for the hypotension remains to be established, but our findings support the idea that endothelial Cx43 gap junctions are involved in maintaining normal vascular function; moreover, these animals provide the opportunity to determine more clearly the role of endothelial Cx43 in vascular development and homeostasis.

NGF-independent survival of postganglionic sympathetic neurons in neuronal-vascular smooth muscle cocultures.

The present study tests the hypothesis that vascular cells promote the survival of postganglionic sympathetic neurons in the absence of nerve growth factor (NGF). To test this hypothesis, neurons isolated from superior cervical ganglia of 2- to 4-day-old rat pups were grown in the absence of NGF and in the absence and presence of vascular smooth muscle cells (VSM). Neuronal survival was assessed as a function of time in culture. At all time points studied, VSM promoted the survival of the neurons. After 5 days in the absence of NGF, 7 +/- 2% of neurons survived in the absence and 28 +/- 7% survived in the presence of VSM. An endothelin receptor antagonist reduced neuronal survival in cocultures grown in the absence of NGF. These data indicate that VSM produce factors other than NGF that promote the survival of cultured postganglionic sympathetic neurons. The data also indicate that endothelin contributes to this effect and suggest that endothelin as well as other VSM-derived factors may play a role in the development of sympathetic innervation to the vasculature.

Transforming growth factor-beta regulation of endothelin expression in rat vascular cell and organ cultures.

Transforming growth factor (TGF)-beta increases the production of the vasoactive peptide endothelin (ET) in cultures of vascular endothelial cells (EC) and vascular smooth muscle cells (VSMC), but the physiologic or pathologic significance of this regulation has not been determined. The present studies test the hypothesis that when EC and VSMC are in direct contact or close proximity, ET expression is, at least in part, dependent on TGF-beta. The effects of TGF-beta on ET-1 mRNA (Northern analysis and reverse transcription polymerase chain reaction) and peptide (radioimmunoassay) levels were assessed in rat EC and VSMC and vascular organ cultures. TGF-beta2 (1 ng/ml) increased ET-1 mRNA in VSMC and EC plus VSMC cultures and increased ET-1 peptide in EC, VSMC, and EC plus VSMC cultures. TGF-beta2 also increased ET-1 mRNA and peptide in vascular organ cultures. Antibodies that neutralized the activities of TGF-beta1 and TGF-beta2 decreased ET-1 mRNA in EC plus VSMC cultures and in vascular organ cultures. These data indicate that when EC and VSMC are in direct contact or close proximity, TGF-beta increases ET expression and active TGF-beta is present and promotes ET expression. These data suggest that TGF-beta is a determinant of vascular ET expression in vivo, and that TGF-beta regulation of ET expression would affect cardiovascular function in health and disease.