Current opinion and controversies of dialyser reuse

Reuse of dialysers has been an integral part of hemodialysis since its inception. Over the past decade, reuse has increased significantly in many countries, most notably in the United States, while vanishing entirely in some other countries, such as Portugal and France. In the United States, which is most widely used as an example because of the large amount of data available, the mortality of dialysis patients has steadily decreased even as reuse has increased. This improvement is probably the result of a complex of factors including understanding the role of comorbidity, treatment unit characteristics, barriers to adequate dialysis, nutrition, anemia, high flux dialysis and dialyser membrane improvements and the desired dialysis dose. Reuse provides a significant economic benefit that allows the use of more efficient and expensive larger biocompatible synthetic membranes to provide high-quality dialysis in the face of cost inflation, limited medical resources and fixed reimbursement. Rather than being legitimized by clinical practice alone, reprocessing, supported by clinical studies, allows the provision of superior treatment to more patients safely and economically. Recent reports concerning dialyser reprocessing have centered not only on morbidity and mortality, but also on questions of the specific effects of different germicides on various types of dialyser membranes (e.g., cellulosic, synthetic, high-flux, etc.) and on the possible role of dialyser reprocessing in the transmission of hepatitis C.

Evaluation of a unique oral contraceptive in the treatment of premenstrual dysphoric disorder

Premenstrual dysphoric disorder (PMDD) is a severe form of premenstrual syndrome (PMS). This is the first trial of a unique oral contraceptive containing a combination of drospirenone (DRSP, 3 mg) and ethinyl estradiol (EE, 30 microg) for the treatment of PMDD. DRSP is a spironolactone-like progestin with antiandrogenic and antimineralocorticoid activity. Spironolactone has been shown to be beneficial in PMS, whereas oral contraceptives have shown conflicting results. In this double-blind, placebo-controlled trial, 82 women with PMDD (Diagnostic and Statistical Manual of Mental Disorders, 4th ed. [DSM IV]) were randomized to receive DRSP/EE or placebo for three treatment cycles. The primary end point was change from baseline in luteal phase symptom scores as assessed on the Calendar of Premenstrual Experiences (COPE) scale. Patients treated with DRSP/EE showed a numerically greater change from baseline compared with those treated with placebo on each of the 22 COPE items and each of the 4 symptom factors. Between-group differences in symptom improvement reached statistical significance in factor 3 only (appetite, acne, and food cravings, p = 0.027). The secondary end points, Beck Depression Inventory (BDI) and Profile of Mood States (PMS), were consistent with the primary end point in that patients treated with the oral contraceptive showed a numerically greater improvement from baseline compared with those treated with placebo. The results of this study show a consistent trend in the reduction of symptoms that suggested a beneficial effect of DRSP/EE for the treatment of PMDD, despite limitations of the study design.

The interaction of microgravity and ethylene on the ultrastructure cell and Ca2+ localization in soybean hook hypocotyl

Calcium ions are secondary messenger in numerous cellular processes of plant grown at 1 g. Ca2+ are connected with oxygen atoms, of pectin carboxy groups and/or with H(+)-groups of protein (Roux and Slocum, 1982; Hepler and Wayne, 1985). The influence of altered gravity on the calcium balance in some cells is established. The increased synthesis of ethylene in plant grown in microgravity caused the change of the structural-functional organization of cell (Hensel and Iversen, 1980; Hilaire et al., 1996). Available data put the new question: how do high ethylene level and microgravity influence on the redistribution of Ca2+ in cell of seedling in early stage of growth? Therefore, the goal of our data was the comparable study of the cell ulltrastructure and localization of Ca2+ in hook hypocotyl of soybean seedling under interaction of microgravity and ethylene.

Health assessment for the occupational and environmental health nurse. Skills update

The assessment and management of clinical problems of employees related to occupational and non-occupational health are key components within the scope of the occupational and environmental health nurse practice. Employees present with various physical or psychosocial problems. The occupational and environmental health nurse must be equipped to make appropriate assessments and decisions related to the employees' care and referral. Use of a structured health assessment tool provides a systematic approach to identification of health needs given the stated goals of maintaining employee health and securing a safe work setting.

GM-CSF mediates alveolar macrophage proliferation and type II cell hypertrophy in SP-D gene-targeted mice

Mice deficient in surfactant protein (SP) D develop increased surfactant pool sizes and dramatic changes in alveolar macrophages and type II cells. To test the hypothesis that granulocyte-macrophage colony-stimulating factor (GM-CSF) mediates alveolar macrophage proliferation and activation and the type II cell hypertrophy seen in SP-D null mice, we bred SP-D and GM-CSF gene-targeted mice to obtain littermate double null, single null, and wild-type mice. Bronchoalveolar lavage levels of phospholipid, protein, SP-D, SP-A, and GM-CSF were measured from 1 to 4 mo. There was an approximately additive accumulation of phospholipid, total protein, and SP-A at each time point. Microscopy showed normal macrophage number and morphology in GM-CSF null mice, numerous giant foamy macrophages and hypertrophic type II cells in SP-D null mice, and large but not foamy macrophages and mostly normal type II cells in double null mice. These results suggest that the mechanisms underlying the alveolar surfactant accumulation in the SP-D-deficient and GM-CSF-deficient mice are different and that GM-CSF mediates some of the macrophage and type II cell changes seen in SP-D null mice.

Diagnosis, pathology, staging, treatment, and outcome of epithelial ovarian neoplasia in patients age < 21 years

BACKGROUND

Epithelial ovarian neoplasms are rare in patients under the age of 21 years. This is a report of a series of such patients documenting their presentation, histologic type, stage of disease, treatment, and outcome.

METHODS

Clinical findings, histology, stage, treatment, and outcomes of 19 patients with epithelial ovarian neoplasia are reported. All histology was rereviewed.

RESULTS

The median age at the time of diagnosis was 19.7 years (range, 14.1-21.8 years), and the median follow-up was 5.6 years (range, 0.2-19.5 years). The most common presenting symptom was dysmenorrhea (100%) followed by abdominal pain (68%), and the initial diagnosis usually was made ultrasonographically. There were nine (47%) serous tumors, 7 (37%) mucinous tumors, 2 (11%) small cell carcinomas, and 1 (5%) endometrioid carcinoma. Seventy-nine percent of tumors were unilateral, and 84% were low malignant potential or well differentiated tumors. Surgical treatment included unilateral salpingo-oophorectomy in 12 patients (63%), total abdominal hysterectomy and bilateral salpingo-oophorectomy in 6 patients (32%), and ovarian cystectomy in 1 patient (5%). Fifteen patients (79%) had Stage I disease, and 4 patients (21%) had Stage III disease at the time of diagnosis. There were two deaths in this series, and both occurred in patients with small cell anaplastic carcinoma.

CONCLUSIONS

Epithelial ovarian neoplasias are rare in patients in this age group but must be included in the differential diagnosis of an ovarian mass. Most patients present with Stage I tumors of low malignant potential. In these patients, good survival is achieved with unilateral salpingo-oophorectomy and preservation of fertility. In contrast, small cell carcinomas are very aggressive, and patients with this variant require intensive therapy.

Primary care patients' personal illness models for depression: a preliminary investigation

BACKGROUND

Despite the fact that more than half of depressed persons are treated for this disorder by primary care physicians, depression is often under-recognized or treated inadequately. There is continued emphasis on effective treatment of depression in primary care patients, but little attention has been paid to the role of the depressed person's illness cognitions in coping with this disorder. Given the often recurring and chronic nature of depression, the individual's self-management strategies may be critical to effective treatment, recovery and remaining well.

OBJECTIVES

The purpose of this pilot study was to determine whether primary care patients' personal illness cognitions for depression are associated with depression coping strategies and treatment-related behaviour.

METHODS

Forty-one primary care patients with depressive symptoms or disorder completed interviews and questionnaires assessing illness cognitions for depression, depression coping strategies and other treatment-related behaviour. Descriptive statistics are used to present patients' illness cognitions for depression. t-tests and correlational analyses were completed to assess the relationship between illness cognitions, depression coping strategies and treatment-related behaviour.

RESULTS

Preliminary data describing illness cognitions for depression are presented. Participants' illness cognitions for depression were significantly associated with current and past treatment-seeking behaviour, medication adherence and coping strategies.

CONCLUSIONS

Although preliminary, these findings indicate that patients' understanding of depression and its consequences are associated with how they manage this illness. Future research is needed to examine the mediating and moderating effects of illness cognitions for depression on medication adherence and other self-management behaviours of depressed primary care patients. Knowledge about primary care patients' personal illness models will aid in the development of adherence interventions, self-management training and support services appropriate to patients' needs in the primary care setting.

Logistic regression when binary predictor variables are highly correlated

Standard logistic regression can produce estimates having large mean square error when predictor variables are multicollinear. Ridge regression and principal components regression can reduce the impact of multicollinearity in ordinary least squares regression. Generalizations of these, applicable in the logistic regression framework, are alternatives to standard logistic regression. It is shown that estimates obtained via ridge and principal components logistic regression can have smaller mean square error than estimates obtained through standard logistic regression. Recommendations for choosing among standard, ridge and principal components logistic regression are developed. Published in 2001 by John Wiley & Sons, Ltd.

Normal personality traits and comorbidity among phobic, panic and major depressive disorders

High comorbidity among anxiety and depressive conditions is a consistent but not well-understood finding. The current study examines how normal personality traits relate to this comorbidity. In the Baltimore Epidemiologic Catchment Area Follow-up Study, psychiatrists administered the full Schedules for Clinical Assessment in Neuropsychiatry to 320 subjects, all of whom completed the Revised NEO Personality Inventory. The disorders of interest were simple phobia, social phobia, agoraphobia, panic disorder, and major depression. Analyses were carried out with second-order generalized estimating equations. The unadjusted summary odds ratio (SOR - or weighted mean odds ratio) for all five disorders was 1.72 (95% confidence interval=1.21-2.46). Neuroticism, introversion, younger age, and female gender were all significant predictors of prevalence of disorders. After adjustment for the relationships between these personality and demographic predictors and prevalence, the association among disorders was much weaker (SOR=1.11, 95% CI=0.79-1.56). However, subjects with high extraversion had a SOR 213% as high (95% CI=102-444%) as those with low extraversion (1.60 vs. 0.75). Therefore, neuroticism and introversion are associated with increased comorbidity due to relationships in common with the prevalence of the different disorders. In contrast, extraversion is associated with increased comorbidity per se.

Absence of germline and somatic p53 alterations in children with sporadic brain tumors

Cancers of the central nervous system are the most common solid tumors of childhood. Although somatic alterations of the p53 tumor suppressor gene have been implicated in brain tumorigenesis, the role of germline p53 mutations in the development of childhood brain tumors has not been well defined. As a component of an ongoing extensive study of the epidemiology of childhood brain tumors, we prospectively examined the germline and tumor p53 gene status in 85 children without a family history of cancer who were diagnosed with a sporadic malignant central nervous system tumor. Using PCR/single-strand conformational polymorphism analysis and direct DNA sequencing, 85 children were screened for the presence of constitutional p53 sequence alterations in exons 2 and 4 through 11. No mutations were identified. Commonly reported sequence polymorphisms were observed at codon 72, as well as in 2 other previously described nucleotide residues. Forty-four brain tumor samples were available for analysis and of these 40 were paired with peripheral blood. Once again, no p53 mutations were found. Of the 5 germline samples with the 2 common polymorphisms, only one had a paired tumor sample for comparison and the tumor contained the same alteration as the germline. Of note, one tumor, a PNET of the cerebellum (medulloblastoma), showed loss of heterozygosity at codon 72. We can conclude that the frequency of germline and somatic p53 mutations in sporadic childhood brain tumors is very low, probably less than 1%, and there is no need to screen these patients routinely for their germline p53 status. However, the potential significance of LOH at codon 72 remains to be elucidated.

Long-term results of arthroscopic partial lateral meniscectomy in knees without associated damage

We evaluated the outcome of partial lateral meniscectomy of 31 knees in 29 patients whose knees were otherwise normal. The mean follow-up was 10.3 years.

According to the Lysholm score, 14 knees were rated as excellent, four as good, five as fair and eight as poor, with a mean score of 80.5 points. Radiologically, only one lateral compartment was classified as grade 0, eight as grade 1, nine as grade 2, 11 as grade 3, and two as grade 4 according to Tapper and Hoover. No significant (p < 0.05) correlation was found between the amount of tissue resected and the subjective, clinical and radiological outcome.

Although early results of lateral meniscectomy may be satisfactory, we have demonstrated that in the long term there was a high incidence of degenerative changes, a high rate of reoperation (29%) and a relatively low functional outcome score.

Long-term results of arthroscopic partial lateral meniscectomy in knees without associated damage

We evaluated the outcome of partial lateral meniscectomy of 31 knees in 29 patients whose knees were otherwise normal. The mean follow-up was 10.3 years. According to the Lysholm score, 14 knees were rated as excellent, four as good, five as fair and eight as poor, with a mean score of 80.5 points. Radiologically, only one lateral compartment was classified as grade 0, eight as grade 1, nine as grade 2, 11 as grade 3, and two as grade 4 according to Tapper and Hoover. No significant (p < 0.05) correlation was found between the amount of tissue resected and the subjective, clinical and radiological outcome. Although early results of lateral meniscectomy may be satisfactory, we have demonstrated that in the long term there was a high incidence of degenerative changes, a high rate of reoperation (29%) and a relatively low functional outcome score.

Management of acute exacerbations of chronic obstructive pulmonary disease: a summary and appraisal of published evidence

PURPOSE

To review critically the available data on diagnostic evaluation, risk stratification, and therapeutic management of patients with acute exacerbations of chronic obstructive pulmonary disease (COPD).

DATA SOURCES

English-language articles were identified by searching MEDLINE (1966 to 2000, week 5), EMBASE (1974 to 2000, week 18), HealthStar (1975 to June 2000), and the Cochrane Controlled Trials Register (2000, Issue 1).

STUDY SELECTION

The best available evidence on each subtopic was selected for analysis. Randomized trials, sometimes buttressed by cohort studies, were used to evaluate therapeutic interventions. Cohort studies were used to evaluate diagnostic tests and risk stratification.

DATA EXTRACTION

Study design and results were summarized in evidence tables. Individual studies were rated by internal validity, external validity, and quality of design. Statistical analyses of combined data were not performed.

DATA SYNTHESIS

Data on the utility of most diagnostic tests are limited. However, chest radiography and arterial blood gas sampling seem useful while acute spirometry does not. Identifiable clinical variables are associated with risk for relapse and risk for death after hospitalization for an acute exacerbation. Evidence of efficacy was found for bronchodilators, corticosteroids, and noninvasive positive-pressure ventilation. There is also support for the use of antibiotics in patients with more severe exacerbations. On the basis of limited data, mucolytics and chest physiotherapy do not seem to be of benefit, and oxygen supplementation seems to increase the risk for respiratory failure only in an identifiable subgroup of patients.

CONCLUSIONS

Although suggestions for appropriate management can be made on the basis of available evidence, the supporting literature is scarce and further high-quality research is necessary. Such research will require an improved, generally acceptable, and transportable definition of acute exacerbation of COPD, as well as improved methods for observing and measuring outcomes.

HLA-B typing by reference strand mediated conformation analysis using a capillary-based semiautomated genetic analyzer

The application of reference strand conformation analysis (RSCA) to HLA-A typing using the ABI PRISM 310 capillary based genetic analyzer has recently been described. This study outlines the development and validation of capillary RSCA for HLA-B typing. Mobility values for 93 HLA-B alleles were defined following electrophoresis of known controls through the system. Three fluorescently labelled references, labelled with three different dyes can be electrophoresed simultaneously. The technique was validated by comparing results from 296 cord blood donors with those obtained using reverse SSO. Following capillary RSCA 14.5% of samples required confirmatory typing, compared with a repeat rate of 5.1% following reverse SSO. In samples where no other typing was necessary there was 100% correlation between the two methods. Capillary RSCA for HLA-B typing is quick, easy to implement, and with the introduction of new FLRs and gel matrices has the potential to evolve into a high resolution typing method.

Quorum-sensing genes in Pseudomonas aeruginosa biofilms: their role and expression patterns

Acylated homoserine lactone molecules are used by a number of gram-negative bacteria to regulate cell density-dependent gene expression by a mechanism known as quorum sensing (QS). In Pseudomonas aeruginosa, QS or cell-to-cell signaling controls expression of a number of virulence factors, as well as biofilm differentiation. In this study, we investigated the role played by the las and rhl QS systems during the early stages of static biofilm formation when cells are adhering to a surface and forming microcolonies. These studies revealed a marked difference in biofilm formation between the PAO1 parent and the QS mutants when glucose, but not citrate, was used as the sole carbon source. To further elucidate the contribution of lasI and rhlI to biofilm maturation, we utilized fusions to unstable green fluorescent protein in concert with confocal microscopy to perform real-time temporal and spatial studies of these genes in a flowing environment. During the course of 8-day biofilm development, lasI expression was found to progressively decrease over time. Conversely, rhlI expression remained steady throughout biofilm development but occurred in a lower percentage of cells. Spatial analysis revealed that lasI and rhlI were maximally expressed in cells located at the substratum and that expression decreased with increasing biofilm height. Because QS was shown previously to be involved in biofilm differentiation, these findings have important implications for the design of biofilm prevention and eradication strategies.

Management of acute exacerbations of COPD: a summary and appraisal of published evidence

STUDY OBJECTIVES

To critically review the available data on the diagnostic evaluation, risk stratification, and therapeutic management of patients with acute exacerbations of COPD.

DESIGN, SETTING, AND PARTICIPANTS

English-language articles were identified from the following databases: MEDLINE (from 1966 to week 5, 2000), EMBASE (from 1974 to week 18, 2000), HealthStar (from 1975 to June 2000), and the Cochrane Controlled Trials Register (2000, issue 1). The best available evidence on each subtopic then was selected for analysis. Randomized trials, sometimes buttressed by cohort studies, were used to evaluate therapeutic interventions. Cohort studies were used to evaluate diagnostic tests and risk stratification. Study design and results were summarized in evidence tables. Individual studies were rated as to their internal validity, external validity, and quality of study design. Statistical analyses of combined data were not performed.

MEASUREMENT AND RESULTS

Limited data exist regarding the utility of most diagnostic tests. However, chest radiography and arterial blood gas sampling appear to be useful, while short-term spirometry measurements do not. In terms of the risk of relapse and the risk of death after hospitalization for an acute exacerbation, there are identifiable clinical variables that are associated with these outcomes. Therapies for which there is evidence of efficacy include bronchodilators, corticosteroids, and noninvasive positive-pressure ventilation. There is also support for the use of antibiotics in patients with more severe exacerbations. Based on limited data, mucolytics and chest physiotherapy do not appear to be of benefit, and oxygen supplementation appears to increase the risk of respiratory failure in an identifiable subgroup of patients.

CONCLUSIONS

Although suggestions for appropriate management can be made based on available evidence, the supporting literature is spotty. Further high-quality research is needed and will require an improved, generally acceptable, and transportable definition of the syndrome "acute exacerbation of COPD" and improved methods for observing and measuring outcomes.

Emergence of Salmonella enteritidis phage type 4 in the Caribbean: case-control study in Trinidad and Tobago, West Indies

A prospective case-control study involving 46 case patients and 92 age- and neighborhood-matched control subjects was conducted in Trinidad and Tobago (T&T) between March 1998 and May 1999 to determine the etiology, sources, and risk factors for Salmonella enteritidis (SE) infection. SE infection in T&T was found to be associated with the consumption of shell eggs, and in particular raw or undercooked eggs. SE isolates from 30 (88%) of 34 patients and from 9 implicated egg or egg-containing food samples were phage type 4. Homemade eggnog and ice cream, cake batter, and egg-containing beverages were the main raw egg-containing foods, reflecting the cultural practices of the people of T&T. Public health education on the risks of eating raw or undercooked eggs, thorough cooking of all egg dishes, and refrigeration of shell eggs and egg dishes; studies tracing infected eggs to their sources; and testing of flocks of layer chickens for SE are needed to reduce the incidence of this infection.

Erythroid Kruppel-like factor (EKLF) coordinates erythroid cell proliferation and hemoglobinization in cell lines derived from EKLF null mice

Erythroid Kruppel-like factor (EKLF) is a transcription factor of the C2H2 zinc-finger class that is essential for definitive erythropoiesis. We generated immortal erythroid cell lines from EKLF(-/-) fetal liver progenitor cells that harbor a single copy of the entire human beta-globin locus and then reintroduced EKLF as a tamoxifen-inducible, EKLF-mutant estrogen receptor (EKLF-ER) fusion protein. Addition of tamoxifen resulted in enhanced differentiation and hemoglobinization, coupled with reduced proliferation. Human beta-globin gene expression increased significantly, whereas gamma-globin transcripts remained elevated at levels close to endogenous mouse alpha-globin transcript levels. We conclude that EKLF plays a role in regulation of the cell cycle and hemoglobinization in addition to its role in beta-globin gene expression. The cell lines we used will facilitate structural and functional analyses of EKLF in these processes and provide useful tools for the elucidation of nonglobin EKLF target genes.

Membrane-perturbing domains of HIV type 1 glycoprotein 41

Structural and functional studies were performed to assess the membrane actions of peptides based on HIV-1 glycoprotein 41,000 (gp41). Previous site-directed mutagenesis of gp41 has shown that amino acid changes in either the N-terminal fusion or N-leucine zipper region depressed viral infection and syncytium formation, while modifications in the C-leucine zipper domain both increased and decreased HIV fusion. Here, synthetic peptides were prepared corresponding to the N-terminal fusion region (FP-I; gp41 residues 519-541), the nearby N-leucine zipper domain (DP-107; gp41 residues 560-597), and the C-leucine zipper domain (DP-178; gp41 residues 645-680). With erythrocytes, FP-I or DP-107 induced dose-dependent hemolysis and promoted cell aggregation; FP-I was more hemolytic than DP-107, but each was equally effective in aggregating cells. DP-178 produced neither hemolysis nor aggregation, but blocked either FP-I- or DP-107-induced hemolysis and aggregation. Combined with previous nuclear magnetic resonance and Fourier transform infrared spectroscopic results, circular dichroism (CD) spectroscopy showed that the alpha-helicity for these peptides in solution decreased in the order: DP-107 >> DP-178 > FP-I. CD analysis also indicated binding of DP-178 to either DP-107 or FP-I. Consequently, DP-178 may inhibit the membrane actions mediated by either FP-I or DP-107 through direct peptide interactions in solution. These peptide results suggest that the corresponding N-terminal fusion and N-leucine zipper regions participate in HIV infection, by promoting membrane perturbations underlying the merging of the viral envelope with the cell surface. Further, the C-leucine zipper domain in "prefusion" HIV may inhibit these membrane activities by interacting with the N-terminal fusion and N-leucine zipper domains in unactivated gp41. Last, exogenous DP-178 may bind to the N-terminal and N-leucine zipper domains of gp41 that become exposed on HIV stimulation, thereby preventing the fusogenic actions of these gp41 regions leading to infection.

Providing information on complementary and alternative therapies and practitioners by producing a directory of practitioners

This article describes the experience of the authors in producing a booklet to provide information on complementary and alternative therapies (CAM) in their local area. The practical steps needed to produce a booklet are described, including ways of involving local general practitioners, meeting with local therapists, recruiting contact persons for each therapy, designing and producing a booklet and launching the final version. The feedback from general practitioners and CAM practitioners is reported.

Role of the 5-HT(2A)receptor and alpha(1)-adrenoceptor in the contractile response of rat pulmonary artery to 5-HT in the presence and absence of nitric oxide

This study investigated the role of 5-HT(2A)receptors and alpha(1)-adrenoceptors in the contractile response to 5-HT in the first branch pulmonary artery of the rat and their interaction with endogenous nitric oxide. 5-HT and phenylephrine induced concentration-dependent contractions. The alpha(1)-adrenoceptor antagonists prazosin, HV723 and phentolamine produced concentration-dependent rightward shifts of the 5-HT concentration-response curves (CRC) consistent with an action at alpha(1)-adrenoceptors. The 5-HT(2)receptor antagonists ritanserin, ketanserin and methysergide produced rightward shifts that were less than would have been predicted for an action solely at 5-HT(2A)receptors. 5-HT and phenylephrine CRCs were shifted to the left by l -NAME. Endothelium denudation also increased the tissue sensitivity to 5-HT. In the presence of l -NAME, ketanserin produced greater antagonism of the 5-HT CRC but not the phenylephrine CRC. Ketanserin also produced greater antagonism of the 5-HT CRC in endothelium denuded rings compared with endothelium intact rings. These findings indicate (a) that both the alpha(1)-adrenoceptor class and the 5-HT(2A)receptor is involved in the contractile response to 5-HT; (b) in the presence of endogenous nitric oxide the contractile response to 5-HT is mediated predominently by alpha(1)-adrenoceptors; (c) inhibition of endogenous nitric oxide potentiates the 5-HT(2A)receptor-mediated component of the contraction.