Benefits of spinal anesthesia for urologic surgery in the youngest of patients.

INTRODUCTION: Increasing concerns regarding potential negative effects of early use of inhalational and intravenous anesthetics on neurocognitive development have led to a growing interest in alternative forms of anesthesia in infants. The study institution's outcomes with spinal anesthesia (SA) for urologic surgery in infants aged less than 90 days are reported and their outcomes with a matched cohort of patients who underwent general anesthesia (GA) are compared. METHODS: This is a retrospective single-center analysis. Patients aged less than 90 days who underwent SA for four urologic surgeries (inguinal hernia repair, scrotal exploration, posterior urethral valve ablation, and ureterocele puncture) were identified from the study institution's SA database. An age- and procedure-matched control cohort was identified from a list of patients who underwent the aforementioned four procedures under GA since 2013. Outcomes of interest included success rate of SA, complications from spinal placement, narcotic use, need for supplemental medications and oxygen, and length of hospital stay. RESULTS: Forty patients were identified; 20 in the SA and 20 in the GA group. Mean patient age was 54 (standard deviation, 35) days. There were no significant differences between the groups in age, gender, weight, history of prematurity, or presence of comorbidities. Eighty percent of SA patients had successful SA; reasons for conversion to GA included failure of spinal needle placement (75%) and agitation during operative procedure (25%). Ninety-six percent of patients who received GA (primarily or converted) had an endotracheal tube (ETT) placed. No patient in the SA group had a complication from spinal needle placement. Patients in the SA group were less likely to receive narcotics during the operative procedure (P = 0.001) and also had a lower mean morphine equivalent dose/kilogram (P = 0.002). Patients in the SA group were also less likely to receive any supplemental medications during the operative procedure (P = 0.001), particularly intravenous corticosteroids (P < 0.001). There were no significant differences in the length of hospital stay. CONCLUSIONS: The use of SA has clear advantages for this medically vulnerable population. For the majority of patients, it obviates the need for ETT placement and airway management and avoids the potential negative effects of GA on neurocognitive development. It also decreases the use of narcotics and other supplemental medications. In scenarios in which the benefit of surgery must be weighed against the risk of GA, such as neonatal torsion, SA may allow a paradigm shift in the timing of surgery.

Urinary antimicrobial peptides: Potential novel biomarkers of obstructive uropathy.

INTRODUCTION: Antimicrobial peptides (AMPs) have historically been evaluated for their role in protecting against uropathogens. However, there is mounting evidence to support their expression in noninfectious injury, with unclear meaning as to their function. It is possible that AMPs represent urothelial injury. Urinary tract obstruction is known to alter the urothelium; however, AMPs have not been evaluated for expression in this noninfectious injury. OBJECTIVE: A pilot study to compare urinary AMP expression in children undergoing surgical intervention for ureteropelvic junction obstruction (UPJO) with nonobstructed controls. STUDY DESIGN: Bladder urine was collected from consenting/assenting pediatric patients with UPJO at intervention. Control bladder urines were obtained from age-matched and sex-matched healthy children without known obstruction or infection. Enzyme-linked immunosorbent assays were run for the following AMPs: ß defense 1 (BD-1), neutrophil gelatinase-associated lipocalin (NGAL), cathelicidin (LL-37), hepatocarcinoma-intestine-pancreas/pancreatitis-associated protein (HIP/PAP), and human α defensin 5 (HD-5); and normalized to urine creatinine. Results were analyzed with Student's t-test or Mann-Whitney U test, when appropriate, and receiver operating characteristic curves. A P-value of <0.05 was considered significant. RESULTS: Thirty bladder urine samples were obtained from children with UPJO at the time of decompressive intervention. Mean patient age was 4.7 years (range 0.3-18.4); 20 (67%) patients were male. Fifteen bladder urine samples were obtained from age-matched and sex-matched controls. Urinary AMP levels were significantly higher in UPJO patients than controls for BD-1 (P = 0.015), NGAL (P < 0.001), LL-37 (P < 0.001), and HIP/PAP (P = 0.046). Optimal threshold values of these AMPs were determined, with each demonstrating significant odds ratios of predicting urinary obstruction. DISCUSSION: Certain urinary AMPs are altered even in noninfectious urinary tract pathology. This represents a novel induction of AMP expression, as the current study is the first to report elevations in BD-1 and HIP/PAP in urinary tract obstruction. This suggests other roles for these AMPs outside of their antimicrobial properties, and likely is a reflection of the urothelial and tubular stress resulting from obstructive uropathy. CONCLUSIONS: Induction of AMPs BD-1, NGAL, LL-37, and HIP/PAP was found to occur in urinary tract obstruction. Further evaluation of AMP expression as a biomarker of uroepithelial injury outside of infection is indicated.

Sacral nerve stimulation for constipation and fecal incontinence in children: Long-term outcomes, patient benefit, and parent satisfaction.

OBJECTIVE: To evaluate the long-term efficacy of sacral nerve stimulation (SNS) in children with constipation and describe patient benefit and parent satisfaction. METHODS: Using a prospective patient registry, we identified patients <21 years old with constipation treated with SNS for >2 years. We compared symptoms, medical treatment, PedsQL Gastrointestinal Symptom Scale (GSS), Fecal Incontinence Quality of Life Scale (FIQL), and Fecal Incontinence Severity Index (FISI) before SNS and at follow-up. We contacted parents to administer the Glasgow Children's Benefit Inventory (GCBI) and a parent satisfaction questionnaire. KEY RESULTS: We included 25 children (52% male, median age 10 years): 16 had functional constipation, six anorectal malformation, two tethered spinal cord, and one Hirschsprung's disease. Defecation frequency did not change after SNS but patients reporting fecal incontinence decreased from 72% to 20% (P<.01) and urinary incontinence decreased from 56% to 28% (P=.04). Patients using laxatives decreased from 64% to 44% (ns) and patients using antegrade enemas decreased from 48% to 20% (P=.03). GSS, most FIQL domains, and FISI were improved at follow-up. Six (24%) patients had complications requiring further surgery. Of the 16 parents contacted, 15 (94%) parents indicated positive health-related benefit and all would recommend SNS to other families. CONCLUSIONS & INFERENCES: Sacral nerve stimulation is a promising and durable treatment for children with refractory constipation, and appears particularly effective in decreasing fecal incontinence. Although a quarter of patients experienced complications requiring additional surgery, nearly all parents reported health-related benefit. Future studies to identify predictors of treatment response and complications are needed.

The modified Ulaanbaatar procedure: Reduced complications and enhanced cosmetic outcome for the most severe cases of hypospadias.

INTRODUCTION/OBJECTIVE: Proximal hypospadias is one of the most challenging conditions that pediatric urologists have to deal with. Many procedures have been devised over the years, but nothing has been proven to be the best option. Although there have been some attempts at correcting severe hypospadias in one procedure, most have advocated a staged approach. The classic approach - laying penile skin or a graft within a split glans followed by glanuloplasty at the second stage - by definition requires two operations on the glans. In the Ulaanbaatar procedure the distal glanular urethra is constructed at the first stage, allowing for a single glans procedure and thus potentially better cosmetic outcomes. The present study discusses experience with the Ulaanbaatar procedure for severe hypospadias. STUDY DESIGN: The study retrospectively reviewed every child who underwent both stages of this procedure at the present institution. It reviewed age, associated diagnoses, surgical technique and outcomes. SURGICAL TECHNIQUE: The first stage was analogous to a classic first-stage procedure with regard to division of the urethral plate and correction of penile curvature. However, an island flap of preputial skin was mobilized and tubularized to create the glanular urethra. No attempt was made to bridge the native meatus and this reconstructed urethra, and the remaining penile skin was placed between the two. The second stage was performed 6 months later by tubularizing the penile skin between the two meatuses. RESULTS: The series consisted of 34 boys. Mean age at surgery was 18.3 months (range 6-118). Nineteen underwent evaluation for genital ambiguity at birth (56%). Thirty (88%) received pre-operative testosterone or human chorionic gonadotropin (HCG). After urethral plate transection, persistent curvature was addressed during the first stage, with dorsal plication in 12 (35%), urethral plate transection alone in six (18%) or ventral grafting with small intestinal submucosa in 16 (47%). Twenty-three boys (67%) had the neourethra tunneled through the glans, and 11 (33%) had the glans split followed by glanuloplasty. Average time between the two stages was 7 months (range 4.0-13.9). Four patients (12%) developed urethral diverticula that required repair. One developed recurrent epididymitis related to an abnormal ejaculatory duct (no stricture) and underwent vasectomy. No patient developed a fistula. Mean length of follow-up was 15.2 months (range 0.3-55.5). DISCUSSION: This modification of the classic staged hypospadias repair may allow for better cosmetic outcome, since the majority of boys required no formal glanuloplasty. There were reduced complications, perhaps because the urethral defect acted like a controlled fistula, allowing for better tissue healing prior to final urethral reconstruction.

Ureteroureterostomy irrespective of ureteral size or upper pole function: a single center experience.

OBJECTIVE: Although ureteroureterostomy (UU) is an established procedure for the treatment of duplex anomalies, there may be a reluctance to apply this approach to patients with poor upper pole function and/or marked degrees of ureteral dilation. METHODS: An institutional review board (IRB)-approved retrospective analysis of all patients undergoing UU between 2006 and present was performed. All patients underwent an end-to-side anastomosis with a double-J stent left in the lower pole ureter. Laparoscopic repairs were done 'high' and open repairs were done 'low'. If the upper pole ureter remained massively dilated after transection, the ureter was partially closed to reduce the length of the anastomosis. Data collected included demographics, diagnosis, surgical interventions, imaging studies and outcomes. RESULTS: A total of 41 patients (43 renal units) were identified. There were 35 females and six males with an average age at surgery of 2.3 years (range 55 days to 15.9 years) and an average follow up of 2.8 years. Diagnosis included ureterocele (17), ectopic duplex ureter (25) and ureteral triplication (1). Thirty-six patients underwent UU only and five underwent UU with simultaneous lower pole reimplantation. Twelve of the 41 patients (29%) underwent laparoscopic repair. Twelve of the 43 renal units (28%) required ureteral tapering, of which three were performed laparoscopically. Preoperative median upper pole function was 17% (0-35%). Six patients had no measurable function and ten had < 15%. No patient developed lower pole hydronephrosis in the follow-up period. There were two complications: one patient was found to have a post-operative ureterovesical junction (UVJ) stricture and the second had an anastomotic stricture. CONCLUSION: Ureteroureterostomy is a safe and effective technique for the reconstruction of duplex anomalies, even with a massively dilated and poorly functioning upper pole moiety. With no identifiable negative effect on the lower pole system, the concept of automatically removing 'dysplastic' upper pole segments can be challenged.

Shared expectations for protection of identifiable health care information: report of a national consensus process.

OBJECTIVE: The Ethical Force Program is a collaborative effort to create performance measures for ethics in health care. This report lays out areas of consensus that may be amenable to performance measurement on protecting the privacy, confidentiality and security of identifiable health information. DESIGN: Iterative consensus development process. PARTICIPANTS: The program's oversight body and its expert panel on privacy include national leaders representing the perspectives of physicians, patients, purchasers, health plans, hospitals, and medical ethicists as well as public health, law, and medical informatics experts. METHODS AND MAIN RESULTS: The oversight body appointed a national Expert Advisory Panel on Privacy and Confidentiality in September 1998. This group compiled and reviewed existing norms, including governmental reports and legal standards, professional association policies, private organization statements and policies, accreditation standards, and ethical opinions. A set of specific and assessable expectations for ethical conduct in this domain was then drafted and refined through 7 meetings over 16 months. In the final 2 iterations, each expectation was graded on a scale of 1 to 10 by each oversight body member on whether it was: (1) important, (2) universally applicable, (3) feasible to measure, and (4) realistic to implement. The expectations that did not score more than 7 (mean) on all 4 scales were reconsidered and retained only if the entire oversight body agreed that they should be used as potential subjects for performance measurement. Consensus was achieved on 34 specific expectations. The expectations fell into 8 content areas, addressing the need for transparency of policies and practices, consent for use and disclosure of identifiable information, limitations on information that can be collected and by whom, individual access to one's own health records, security requirements for storage and transfer of information, provisions to ensure ongoing data quality, limitations on how identifiable information may be used, and provisions for meaningful accountability. CONCLUSIONS: This process established consensus on 34 measurable ethical expectations for the protection of privacy and confidentiality in health care. These expectations should apply to any organization with access to personally identifiable health information, including managed care organizations, physician groups, hospitals, other provider organizations, and purchasers. Performance measurement on these expectations may improve accountability across the health care system.

Electromyographic analysis of deltoid and rotator cuff function under varying loads and speeds.

The purpose of this study was to compare the effect of increasing loads and doubling speed on the deltoid and rotator cuff muscles during isotonic scapular plane abduction (scaption) with neutral humeral rotation. These muscles were studied in 16 volunteers with asymptomatic shoulders with the use of fine wire electromyography. The addition of load to the arm during scaption caused an increase in electromyographic activity during the first 90 degrees of motion. Furthermore electromyographic activity decreased during the final 30 degrees of motion with each increase in load. Doubling the speed caused an increase in electromyographic activity during the first 60 degrees of motion while causing a decrease in activity in the final 60 degrees. This study demonstrates the response of the rotator cuff and deltoid muscles to varying loads and speeds during the most basic shoulder motion. With the data obtained in this study, rehabilitation exercises and experimental shoulder models can be refined to reflect this more physiologic situation.

What to do if your facility is raided by the federal government.

A raid at your facility? Federal agents with guns, bulletproof vests and handcuffs ... sounds impossible and scary, doesn't it? Learn how to prepare and reduce the trauma of this difficult situation.

15-HETE-substituted diglycerides selectively regulate PKC isotypes in human tracheal epithelial cells.

Human tracheal epithelial (TE) cells selectively incorporate their major lipoxygenase product, 15-hydroxyeicosatetraenoic acid (15-HETE), into the sn-2 position of phosphatidylinositol (PI) (S. E. Alpert and R. W. Walenga. Am. J. Respir. Cell Mol. Biol. 8: 273-281, 1993). Here we investigated whether 15-HETE-PI is a substrate for receptor-mediated generation of 15-HETE-substituted diglycerides (DGs) and whether these 15-HETE-DGs directly activate and/or alter conventional diacylglycerol-induced activation of protein kinase C (PKC) isotypes in these cells. Primary human TE monolayers incubated with 0.5 microM 15-[3H]-HETE or 15-[14C]HETE for 1-2 h were stimulated with 1 nM to 1 microM platelet-activating factor (PAF) for 30 s to 6 min, and the radiolabel in the medium, cellular phospholipids, and neutral lipids was assessed by high-performance liquid and thin-layer chromatography. PAF mobilized radiolabel from PI in a dose-dependent manner (22 +/- 5% decrease after 1 microM PAF) without a concomitant release of free intra- or extracellular 15-HETE. 14C-labeled DGs were present in unstimulated TE monolayers incubated with 15-[14C]HETE, and the major 14C band, identified as sn-1,2-15-[14C]HETE-DG, increased transiently in response to PAF. Western blots of freshly isolated and cultured human TE cells revealed PKC isotypes alpha, betaI, betaII, delta, epsilon, and zeta. In vitro, cell-generated sn-1, 2-15-[14C]HETE-DG selectively activated immunoprecipitated PKC-alpha and inhibited diacylglycerol-induced activation of PKC-alpha, -delta, -betaI, and -betaII. Our observations indicate that 15-HETE-DGs can modulate the activity of PKC isotypes in human TE cells and suggest an intracellular autocrine role for 15-HETE in human airway epithelia.

Decreased dopamine beta-hydroxylase activity in unipolar geriatric delusional depression.

BACKGROUND: Decreased dopamine beta-hydroxylase (DBH) activity has been reported in unipolar psychotic depression. DBH comparisons between elderly delusional and nondelusional depressives and controls and determination of whether pretreatment group differences persist have not been reported. Our objective was to compare DBH activity in elderly delusional major depressives with that of nondelusional depressives and normal control subjects before and after hospital treatment. METHODS: Enzyme activity was assessed after hospital admission. A subsample had predischarge assessments. Treatment was not controlled but accounted for in analyses. Electroconvulsive therapy subjects were medication-free for posttreatment assays. RESULTS: Baseline and predischarge DBH assays were lower in subjects with delusional depression than in either comparison group. Despite high intraindividual correlation, treatment was associated with significant increases in activity in the clinical groups. CONCLUSIONS: Patients with late-life delusional depression have lower DBH activity before and after hospital treatment than age-matched nondelusional patients or normal controls.

Ozone inactivates cyclooxygenase in human tracheal epithelial cells without altering PGHS-2 mRNA or protein.

Exposure of human tracheal epithelial (TE) cells to ozone (0.1-0.5 ppm) leads to a transient increase followed by decreased production of prostaglandin (PG) E2 concomitant with dose-dependent loss and delayed recovery of cyclooxygenase (CO) activity [S.E. Alpert and R.W. Walenga. Am. J. Physiol. 269 (Lung Cell. Mol. Physiol. 13): L734-L743, 1995]. Formation of reactive oxygen species (ROS) in cultured tracheobronchial epithelial cells during ozone exposure was recently demonstrated (L.C. Chen and Q.Qu. Toxicol. Appl. Pharmacol. 143: 96-101, 1997). In the present study, we investigated if ROS generated by ozone-exposed human TE cells contribute to PGE2 production and/or CO inactivation and whether the delay in recovery of CO activity after ozone reflects impaired gene transcription and/or protein synthesis. Rapid, dose-dependent ROS generation, assessed by fluorescence of dihydrorhodamine 123, was detected in human TE monolayers exposed to 0.21-0.63 ppm ozone. In a different system, TE cells were exposed to air or 0.5 ppm ozone for 1 h by serial renewal/collection of an adherent film of media. Ozone-induced ROS formation, the transient increase and decline in PGE2, and CO inactivation were attenuated by an intracellular hydroxyl radical scavenger, 1,3-dimethyl-2-thiourea. Ibuprofen, a reversible CO inhibitor, prevented PGE2 release during ozone exposure (and hence autocatalytic CO inactivation) but not loss of CO activity. Although CO activity remained depressed for hours after ozone exposure, compared with air-exposed cultures, no differences were detected in mRNA and protein levels of prostaglandin endoperoxide G/H synthase 2 (PGHS-2), the only CO isoform present in human TE cells, or in the rate of de novo PGHS-2 synthesis. Our findings suggest that ozone-induced PGE2 production and CO inactivation are primarily the result of formation of intracellular oxidant molecules and that delayed recovery of CO activity in human TE cells after short-term ozone exposure is due to persistent inactivation of PGHS-2, rather than to interference with its synthesis.

Pubic rami fracture: a benign pelvic injury?

OBJECTIVE: To present a consecutive series of older patients with pubic rami fractures and evaluate their long term functional outcome. STUDY DESIGN: Retrospective. METHODS: Sixty-three consecutive community-dwelling, ambulatory patients who sustained a public rami fracture and were treated at one hospital were reviewed. Fifty-two of sixty-three patients (83%) had radiographic evidence of pubic rami fracture at initial presentation; in the remaining eleven patients, the diagnosis of pubic rami fracture was made after additional imaging studies. Sixty patients (95%) required hospitalization for pain control and progressive mobilization. RESULTS: The hospital length of stay for the sixty admitted patients averaged fourteen days; patients who had three or more associated medical comorbidities or required use of a cane or walker for ambulation prior to fracture were more likely to have been hospitalized greater than two weeks. Thirty-eight patients were available for one year minimum follow-up; thirty-five of thirty-eight patients (92%) were living at home, 84% had no or mild complaints of hip/groin pain, 92% had returned to their prefracture ambulatory status, and 95% had returned to their performance function in activities of daily living. CONCLUSIONS: 1) Elderly patients with pubic rami fractures utilize substantial healthcare resources based upon length of stay and need for home care services; and 2) those patients who survive have a good prognosis with regard to long term pain relief and functional outcome.

Patient safety and efficacy as measured by clinical trials and regulatory policy.

Virtual Reality and other technological innovations in medicine provide new challenges to the regulatory framework of the premarket review process for medical devices. By reinventing the government-academia-industry partnership, clinical trial data necessary for a medical device to enter the market can be more efficiently obtained.

The relationship of granzyme A and perforin expression to cardiac allograft rejection and dysfunction.

The mechanisms underlying contractile dysfunction following heart transplantation are poorly defined. To investigate the role of cytotoxic T cells (CTL) in cardiac transplant rejection, and during episodic contractile dysfunction, we performed a prospective study analyzing the expression of granzyme A and perforin, two functional markers of activated CTL. Sixteen consecutive patients were analyzed during the first year posttransplantation. All patients received induction therapy with OKT-3 and received standard three-drug immunosuppression therapy. Rejection status was monitored using routine surveillance endomyocardial biopsy and graded according to the ISHLT scale. Granzyme A and perforin mRNA were detected by reverse transcription PCR at the time of each routine biopsy. A total of 64/123 biopsies were positive for granzyme expression, while 38/123 samples were positive for perforin expression. LV function was monitored using M-mode derived fractional shortening and Doppler assessment of diastolic function (isovolumic relaxation time [IVRT] and pressure half-time [P1/2]). As expected, the presence of granzyme A message was associated with rejection score (ANOVA, P = 0.001). In addition, granzyme A expression was correlated with a decrease in diastolic function (chi 2 = 6.4, P < 0.02), but was not associated with systolic function. The presence of perforin message was not correlated with functional changes or with rejection grade, but was associated with granzyme expression (chi 2 = 9.11, P = 0.0025). These studies suggest that the presence of granzyme A message may be an important predictor of graft function.

Ozone exposure of human tracheal epithelial cells inactivates cyclooxygenase and increases 15-HETE production.

We assessed the immediate and prolonged effects of ozone on arachidonic acid (AA) metabolism by primary cultured human tracheal epithelial (TE) cells. TE monolayers were exposed at a gas-fluid interface to air or 0.1, 0.25, or 0.5 ppm ozone (15 min air, then 45 min air/ozone), and serially collected effluents were analyzed by thin-layer chromatography (TLC) and/or high-performance liquid chromatography. Release of prostaglandin E2 (PGE2) and AA, but not 15-hydroxyeicosatetraenoic acid (15-HETE) or its metabolites, was detected from cultures prelabeled with [14C]AA. PGE2 production, measured by immunoassay, was nearly constant during air exposure. In contrast, PGE2 increased two- to threefold during the first 15-min exposure to all concentrations of ozone, but then progressively declined to 78 +/- 17, 57 +/- 12 (P < or = 0.05), and 45 +/- 15% (P < or = 0.05) of air controls after exposure to 0.1, 0.25, and 0.5 ppm ozone. Ozone did not induce a new spectrum of AA metabolites; only PGE2, lesser amounts of PGF2 alpha, and 15-HETE were present in media and cell extracts of air- or ozone-exposed cultures provided with 30 microM exogenous AA. However, cyclooxygenase (CO) activity (PGE2 produced from 30 microM AA) decreased to 82 +/- 9, 53 +/- 8 (P < or = 0.05), and 28 +/- 6% (P < or = 0.05) vs. controls after 0.1, 0.25, and 0.5 ppm ozone, whereas 15-HETE production was unimpaired. When cells exposed to 0.5 ppm ozone were maintained for up to 6 h in 5% CO2-air, spontaneous PGE2 production remained decreased and recovery of CO activity was extremely slow. TLC analysis of lipid extracts from [14C]AA-labeled cells revealed a nearly twofold increase in free intracellular 15-HETE, and hydrolysis of phospholipids demonstrated increased esterified 15-HETE. Exposure of human TE cells to ozone leads to a transient increase followed by prolonged decrease in PGE2 production and increased intracellular retention of 15-HETE. Loss of the bronchodilator and anti-inflammatory properties of epithelial PGE2, with or without increased 15-HETE, might contribute to ozone-induced airway dysfunction.

Exposure to shear stress alters endothelial adhesiveness. Role of nitric oxide.

BACKGROUND: Shear stress increases the release of nitric oxide (NO) by endothelial cells (ECs). We and others have provided evidence that endothelium-derived NO inhibits monocyte adhesion to the vessel wall. We therefore hypothesized that previous exposure to shear stress would inhibit endothelial adhesiveness for monocytes by virtue of its effect to increase NO release. METHODS AND RESULTS: Confluent monolayers of bovine aortic endothelial cells, human aortic endothelial cells, or human venous endothelial cells were exposed to laminar fluid flow. Culture media were collected for measurement of NO (by chemiluminescence) and the prostacyclin metabolite 6-keto-prostaglandin F1 alpha. NOx and 6-keto-prostaglandin F1 alpha accumulated in the conditioned medium during laminar fluid flow from 30 minutes to 24 hours in a time-dependent fashion. In another set of studies, ECs previously exposed to flow or to static conditions were washed with Hanks' buffer and exposed to THP-1 cells for 30 minutes. Adherent cells were counted by microscopy. Previous exposure to flow reduced endothelial adhesiveness for monocytes by 50% (P < .05). The effect of flow on endothelial adhesiveness occurred within 30 minutes. This effect was abrogated by nitro-L-arginine (an antagonist of NO synthesis), as well as by tetraethylammonium ion (an antagonist of the flow-activated potassium channel); the effects of these inhibitors were reversed by the NO donor SPM-5185. Although the cyclo-oxygenase inhibitor indomethacin totally inhibited the flow-induced production of prostacyclin by ECs, it minimally affected adherence of THP-1 cells. The early effect of flow on endothelial adhesiveness was not mediated by alterations in the expression of the endothelial adhesion molecules VCAM-1 or ICAM-1 as assessed by fluorescent activated cell sorting. CONCLUSIONS: Shear stress alters endothelial adhesiveness for monocytes; at early time points, this effect is largely due to flow-stimulated release of NO and, to a lesser extent, prostacyclin. This effect of flow occurs within 30 minutes and is probably due to alterations in the signal transduction or activation state (rather than the expression) of endothelial adhesion molecules.