Skin-Related complications of Klippel-Trenaunay Syndrome: a retrospective review of 410 patients

BACKGROUND

Little is known about skin-related complications in Klippel-Trenaunay syndrome (KTS), a complex vascular anomaly defined by capillary malformation (CM), venous malformation (VM) ± lymphatic malformation (LM) and limb overgrowth. Reported skin-related complications of KTS include ulceration, vascular ectasias (blebs), bleeding and infection.

OBJECTIVE

To determine the spectrum, prevalence and predictors of skin-related complications in KTS.

METHODS

A retrospective review of 410 patients fulfilling KTS criteria was performed to assess for the presence of skin-related complications.

RESULTS

Skin-related complications were present in 45% of patients. Most prevalent were CM-related complications including blebs, bleeding, thickening (25%), cellulitis (22%) and ulceration (21%). Features positively associated with skin-related complications were presence of LM (OR 17.17; P < 0.001), VM on the buttocks/perineum/genitalia (OR 1.92; P = 0.009), CM on the feet (OR 1.77; P = 0.039) and male sex (OR 1.63; P = 0.034). Features negatively associated with skin-related complications were CM on the trunk (OR 0.59; P = 0.029) and tissue hypertrophy of the hands (OR 0.27; P = 0.025).

CONCLUSION

Skin-related complications affect nearly half of patients with KTS. Those with lymphatic involvement or malformation presence in the undergarment area or feet are most at risk.

The 2018 rift eruption and summit collapse of Kīlauea Volcano

In 2018, Kīlauea Volcano experienced its largest lower East Rift Zone (LERZ) eruption and caldera collapse in at least 200 years. After collapse of the Pu'u 'Ō'ō vent on 30 April, magma propagated downrift. Eruptive fissures opened in the LERZ on 3 May, eventually extending ~6.8 kilometers. A 4 May earthquake [moment magnitude (M _w) 6.9] produced ~5 meters of fault slip. Lava erupted at rates exceeding 100 cubic meters per second, eventually covering 35.5 square kilometers. The summit magma system partially drained, producing minor explosions and near-daily collapses releasing energy equivalent to M _w 4.7 to 5.4 earthquakes. Activity declined rapidly on 4 August. Summit collapse and lava flow volume estimates are roughly equivalent-about 0.8 cubic kilometers. Careful historical observation and monitoring of Kīlauea enabled successful forecasting of hazardous events.

Juvenile idiopathic arthritis and future risk for cardiovascular disease: a multicenter study

OBJECTIVES

To evaluate the frequency of cardiovascular disease (CVD) and CVD risk factor development in adult patients previously diagnosed with juvenile idiopathic arthritis (JIA).

METHOD

A cohort study was conducted utilizing patients at two academic institutions (cohorts 1 and 2). Each institution evaluated the common endpoint of CVD outcomes and CVD risk factor development in adults aged ≥ 30 years and at the 29-year follow-up from disease onset in cohorts 1 and 2, respectively, with comparison to control groups of similar age and sex.

RESULTS

Cohort 1 included 41 patients with JIA and follow-up ≥ 30 years of age with comparison to 41 controls. Three patients (7%) had CVD, compared to one control (2%; p = 0.31). Cohort 2 included 170 patients with JIA and a median of 29 years of follow-up from disease onset with comparison to 91 controls. Two patients (2%) had CVD, compared to none of the controls (p = 0.29). The presence of CVD risk factors was found to be increased in the JIA group compared to the controls in three categories: family history of CVD (cohort 1), hypertension (cohort 2), and ever smokers (cohorts 2).

CONCLUSIONS

There is no increase in CVD events in patients with JIA 29 years following disease onset when compared to the general population. As these cohorts age, it will be informative to evaluate whether this baseline risk remains present or a trend towards increasing CVD emerges. Continued longitudinal follow-up of these cohorts and larger population-based studies are needed to establish a definitive relationship between JIA and CVD.

Influence of secondary aspiration on human aspiration efficiency

Computational fluid dynamics (CFD) was used to evaluate the contribution of secondary aspiration to human aspiration efficiency estimates using a humanoid model with realistic facial features. This study applied coefficient of restitution (CoR) values for working-aged human facial skin to the facial regions on the humanoid CFD model. Aspiration efficiencies for particles ranging from 7 to 116 μm were estimated for bounce (allowing for secondary aspiration) and no-bounce (CoR=0) simulations. Fluid simulations used the standard k-epsilon turbulence model over a range of test conditions: three freestream velocities, two breathing modes (mouth and nose breathing, using constant inhalation), three breathing velocities, and five orientations relative to the oncoming wind. Laminar particle trajectory simulations were used to examine inhaled particle transport and estimate aspiration efficiencies. Aspiration efficiency for the realistic CoR simulations, for both mouth- and nose-breathing, decreased with increasing particle size, with aspiration around 50% for 116 μm particles. For the CoR=0 simulations, aspiration decreased more rapidly with increasing particle size and approached zero for 116 μm compared to realistic CoR models (differences ranged from 0% to 80% over the particle sizes and velocity conditions). Differences in aspiration efficiency were larger with increasing particle size (>52 μm) and increased with decreasing freestream velocity and decreasing breathing rate. Secondary aspiration was more important when the humanoid faced the wind, but these contributions to overall aspiration estimates decreased as the humanoid rotated through 90°. There were minimal differences in aspiration between uniform CoR values of 0.5, 0.8, 1.0 and realistic regionally-applied CoR values, indicating differences between mannequin surfaces and between mannequin and human skin will have negligible effect on aspiration for facing-the-wind orientation.

Variability in coefficient of restitution in human facial skin

BACKGROUND

If particles rebound on human facial skin, they can be re-entrained into the airflow and subsequently inhaled, increasing aspiration efficiency estimates. A realistic estimate of facial skin coefficient of restitution (CoR) is necessary to accurately model particle bounce. This study investigated the effects of sampling location, temperature, humidity levels, age, gender, and BMI on facial skin CoR.

METHODS

A torsional ballistometer was used to measure facial CoR for 30 participants divided into three age groups (18-30, 31-40, and 41-65 years), at three temperatures and three humidity levels. The study was repeated twice: once in the late winter and once in the early summer to capture the seasonal variability.

RESULTS

The CoR significantly varied across five facial locations, with values ranging from 0.55 to 0.75. Gender, sampling season and the interaction between sampling location and age were found to be significant, but changes in values were relatively small (0.05 at most) and are not considered practically significant.

CONCLUSION

CoR was non-uniform across the face. The use of uniform CoR value as modeling input parameters or for mannequin facial surfaces in experimental wind tunnel studies may not be accurate due to the high variability in CoR between facial sampling locations.

Gene delivery to dendritic cells facilitated by a tumor necrosis factor alpha-competing peptide

Efficient gene delivery systems tailor-designed for dendritic cells (DCs) would allow the possibility of therapeutic manipulation of a wide spectrum of immune functions. Toward achieving this goal, we have identified a novel heptameric peptide (YTYQGKL) that functions as a localization moiety to mediate gene transfer in murine DCs. The sequence was identified by screening a phage display library against a DC cell line (JAWSII) using mouse TNFalpha as the eluting ligand. Alignment analysis reveals YTYQGKL resembles a solvent accessible region in mouse and human TNFalpha structures. A cyclized synthetic peptide bearing the sequence CYTYQGKLC binds to DCs in a concentration-dependent manner. Appending the cyclic peptide to a DNA binding domain (16 consecutive lysine residues) enhances transfection of reporter gene-encoding plasmids in JAWSII cells and in bone marrow derived primary DCs (BMDC). Further enhancement of gene transfer was observed when the peptide-DNA construct was anchored onto polymeric microspheres, with up to 25% of BMDC expressing the transgene. Exposing cells to the free peptide prior to transfection significantly diminished transgene expression. These results demonstrate that YTYQGKL can be used to facilitate gene transfer in DCs.

Mechanosensitive endothelial gene expression profiles: scripts for the role of hemodynamics in atherogenesis?

The possibility that hemodynamic forces can act as a "local risk factor" for endothelial dysfunction provides a conceptual framework for the longstanding observation that the earliest lesions of atherosclerosis develop in a nonrandom pattern, the geometries of which correlate with branch points and other regions of altered blood flow. This has led us to hypothesize that hemodynamic forces, in particular wall shear stresses generated by complex patterns of blood flow, can function as both positive and negative stimuli in atherogenesis via effects on endothelial cell gene expression. To understand how endothelial cells in different regions of the arterial tree acquire both functional and dysfunctional phenotypes due to regional hemodynamics, it was important to begin to delineate, in a comprehensive fashion, the mechanoresponsiveness of endothelial cells. To address this fundamental question, we undertook high-throughput transcriptional profiling to assess the global patterns of gene expression in cultured endothelial cells exposed to two defined biomechanical stimuli. Analyses of the transcriptional activity of thousands of genes have revealed unique patterns of gene expression associated with certain types of stimuli. These unique gene expression programs and their associated functional phenotypes constitute the strongest evidence to date that vascular endothelial cells can discriminate among different types of biomechanical stimuli. The results of these studies and the working hypotheses inspired by detailed molecular analyses of biomechanically activated vascular endothelium promise to provide new insights into the role of hemodynamics in the pathogenesis of atherosclerosis.

Biomechanical activation of vascular endothelium as a determinant of its functional phenotype

One of the striking features of vascular endothelium, the single-cell-thick lining of the cardiovascular system, is its phenotypic plasticity. Various pathophysiologic factors, such as cytokines, growth factors, hormones, and metabolic products, can modulate its functional phenotype in health and disease. In addition to these humoral stimuli, endothelial cells respond to their biomechanical environment, although the functional implications of this biomechanical paradigm of activation have not been fully explored. Here we describe a high-throughput genomic analysis of modulation of gene expression observed in cultured human endothelial cells exposed to two well defined biomechanical stimuli-a steady laminar shear stress and a turbulent shear stress of equivalent spatial and temporal average intensity. Comparison of the transcriptional activity of 11,397 unique genes revealed distinctive patterns of up- and down-regulation associated with each type of stimulus. Cluster analyses of transcriptional profiling data were coupled with other molecular and cell biological techniques to examine whether these global patterns of biomechanical activation are translated into distinct functional phenotypes. Confocal immunofluorescence microscopy of structural and contractile proteins revealed the formation of a complex apical cytoskeleton in response to laminar shear stress. Cell cycle analysis documented different effects of laminar and turbulent shear stresses on cell proliferation. Thus, endothelial cells have the capacity to discriminate among specific biomechanical forces and to translate these input stimuli into distinctive phenotypes. The demonstration that hemodynamically derived stimuli can be strong modulators of endothelial gene expression has important implications for our understanding of the mechanisms of vascular homeostasis and atherogenesis.

Endothelial gene regulation by laminar shear stress

Endothelial cells, because of their unique localization, are constantly exposed to fluid mechanical forces derived by the flowing blood. These forces, and more specifically shear stresses; affect endothelial structure and function, both in vivo and in vitro, and are implicated as contributing factors in the development of cardiovascular diseases. We have demonstrated earlier that the shear stress selectively induces the transcription of several endothelial genes, and have defined a shear stress response element (SSRE) in the promoter of platelet-derived-growth-factor B (PDGF-B), that is shared by additional endothelial shear stress responsive genes. Here we further characterize this SSRE and the nuclear factors that bind to it, and imply the possible role of the endothelium cytoskeleton in transducing shear stress, leading to the expression of PDGF-B/SSRE constructs in transfected endothelial cells exposed to shear stress. We also present, yet a new shear stress response element in the Platelet Derived Growth Factor A promoter, that contains a binding site to the transcription factors egr1/sp1. These results further demonstrate the complexity of gene regulation by hemodynamic forces, and support the important part that these forces have in the physiology and pathophysiology of the vessel wall.

Anti-inflammatory and lung function effects of montelukast in asthmatic volunteers exposed to sulfur dioxide

BACKGROUND

Sulfur dioxide (SO(2)) gas may induce acute asthmatic responses when inhaled by individuals in the setting of community or occupational air pollution during exercise. Some asthma medications mitigate the SO(2) response, which is not fully understood but appears to involve multiple mechanisms.

OBJECTIVE

We tested the hypothesis that pretreatment with the cysteinyl-leukotriene inhibitor montelukast sodium protects against the inflammatory and bronchoconstrictive effects of SO(2) in the airways of asthmatic subjects.

METHODS

Asthmatic volunteers (enrolled, 12 subjects; completed study, 11 subjects) were exposed to 0.75 ppm SO(2) for 10-min periods during exercise (mean ventilation, 35 L/min) and were exposed similarly to filtered air (control condition) after double-blinded pretreatments with montelukast (10 mg/d for 3 days) and placebo.

RESULTS

After montelukast pretreatment, specific airways resistance, FEV(1), symptoms, and eosinophil counts in induced sputum showed statistically and clinically significant improvements in preexposure measurements and/or decreased responses to SO(2) exposure or exercise. The mean FEV(1) immediately after exposure was 95% of baseline FEV(1) with montelukast pretreatment vs 82% with placebo.

CONCLUSION

Montelukast significantly protects against airways eosinophilic inflammation and bronchoconstriction from SO(2) exposure during exercise. This implies a role for leukotrienes in SO(2)-induced lung effects.

CT for the evaluation of flank pain

Unenhanced helical CT allows rapid and accurate determination of whether a stone is present anywhere in the urinary tract. There is a learning curve for both radiologist and urologist, but a number of signs are highly predictive of stone. Helical CT scans should always be accompanied by a "scoutogram" to convey an idea of what the stone might look like. The scan requires no contrast medium and takes only 5 to 10 minutes of imaging time, making it cost effective. It behooves both urologists and radiologists to familiarize themselves with the techniques for reading these scans.

Simple nephrectomy: managing the difficult case: xanthogranulomatous pyelonephritis and autosomal dominant polycystic kidney disease

Laparoscopic surgery for kidneys with xanthogranulomatous pyelonephritis or autosomal dominant polycystic disease has proved to be technically difficult but is possible. The Harmonic Scalpel facilitates the dissection of inflammatory tissues and does not inflict burns. Hand-assisted laparoscopy may be useful. Pain relief is obtained by most patients undergoing cyst drainage, although recurrence after a year or two is common. A specific and detailed preoperative diagnosis and treatment plan are essential to a successful outcome.

Laparoscopic lower urinary tract reconstruction

In the past decade laparoscopy has been successfully utilized for both the obliterative and reconstructive management of urologic disease. We have seen not only an advance in the technology available to perform these procedures, but also an effort on the part of laparoscopic urologists to refine their techniques to allow them to perform more complicated procedures. In the lower urinary tract, the development of reconstructive procedures has been slow. While early interest in laparoscopy prompted several pioneers to perform the initial reconstructive procedures, the difficulties associated with these procedures at that time largely precluded their widespread application or adoption. Recently, improvements in the skills of laparoscopic urologists and the advent of instruments to facilitate suturing (e.g. EndoStitch semi-automatic suturing device, Lapra-Ty clips to replace intracorporeal knotting, and advances in staple and clip technology) have facilitated a renewed interest in laparoscopic reconstructive surgery of the lower urinary tract. At present, almost all types of urologic open reconstructive procedures have been accomplished laparoscopically: urinary diversion (e.g. ureteroileal loop urinary diversion and continent diversion), bladder reconstruction (e.g. ureterovesicostomy, bladder augmentation, bladder diverticulectomy, partial cystectomy), ureteral reimplantation, and, most recently, urethrovesical anastomosis following radical prostatectomy. This article will review the development of these procedures.

Endothelial dysfunction, hemodynamic forces, and atherogenesis

Phenotypic modulation of endothelium to a dysfunctional state contributes to the pathogenesis of cardiovascular diseases such as atherosclerosis. The localization of atherosclerotic lesions to arterial geometries associated with disturbed flow patterns suggests an important role for local hemodynamic forces in atherogenesis. There is increasing evidence that the vascular endothelium, which is directly exposed to various fluid mechanical forces generated by pulsatile blood flow, can discriminate among these stimuli and transduce them into genetic regulatory events. At the level of individual genes, this regulation is accomplished via the binding of certain transcription factors, such as NF kappa B and Egr-1, to shear-stress response elements (SSREs) that are present in the promoters of biomechanically inducible genes. At the level of multiple genes, distinct patterns of up- and downregulation appear to be elicited by exposure to steady laminar shear stresses versus comparable levels of non-laminar (e.g., turbulent) shear stresses or cytokine stimulation (e.g., IL-1 beta). Certain genes upregulated by steady laminar shear stress stimulation (such as eNOS, COX-2, and Mn-SOD) support vasoprotective (i.e., anti-inflammatory, anti-thrombotic, anti-oxidant) functions in the endothelium. We hypothesize that the selective and sustained expression of these and related "atheroprotective genes" in the endothelial lining of lesion-protected areas represents a mechanism whereby hemodynamic forces can influence lesion formation and progression.

A new mathematical approach predicts individual cell growth behavior using bacterial population information

A theoretical methodology has been developed for studying the growth kinetics of bacterial cells. It utilizes the steady-state cell length distribution in a bacterial population to predict the dependency of growth and division rates on cell length and age. The mathematical model has been applied to the analysis of two bacterial populations, a wild-type strain of Bacillus subtilis, and a minicell-producing strain that carries the divIVB1 mutation. The results show that our model describes the wild-type population very well and that the assumptions typically used in traditional methods are unrealistic. In the case of the minicell-producing mutant we find evidence that the rate of cell division must be a function not only of cell size but also of cell age.

From paper to electron: how an STM journal can survive the disruptive technology of the Internet

The Internet represents a different type of technology for publishers of scientific, technical, and medical journals. It is not a technology that sustains current markets and creates new efficiencies but is, rather, a disruptive technology that could radically alter market forces, profit expectations, and business models. This paper is a translation and amplification of the research done in this area, applied to a large-circulation new science journal, Pediatrics. The findings suggest that the journal of the future will be electronic, have a less volatile cost structure, be supported more by services than by content, be less able to rely on subscription revenues, and abandon certain elements of current value networks. It also provides a possible framework for other publishers to use to evaluate their own journals relative to this disruptive technology.

Day-to-day particulate exposures and health changes in Los Angeles area residents with severe lung disease

We measured particulate matter (PM2.5 and PM10) exposures, home temperature, arterial blood oxygen saturation, blood pressure, and lung function in 30 volunteer Los Angeles area residents during four-day intervals. Continuous Holter electrocardiograms were recorded in a subgroup on the first two days. Subjects recorded symptoms and time-activity patterns in diaries during monitoring, and during a reference period one week earlier/later. All subjects had severe chronic obstructive pulmonary disease. PM10 (24-hr mean) at monitoring stations near subjects' homes averaged 33 micrograms/m3, and ranged from 9 to 84 micrograms/m3. In longitudinal analyses, day-to-day changes in PM2.5 and PM10 outside subjects' homes significantly tracked concurrent station PM10 (r2 = 0.22 and 0.44, respectively). Indoor and personal concentrations were less related to station readings (r2 < or = 0.1), but tracked each other (r2 > or = 0.4). In-home temperatures tracked outdoor temperatures more for lows (r2 = 0.27) than for highs (r2 = 0.10). These longitudinal relationships of subject-oriented and station PM measurements were generally similar to cross-sectional relationships observed previously in similar subjects. Among health measurements, only blood pressure showed reasonably consistent unfavorable longitudinal associations with particulates, more with station or outdoor PM than with indoor or personal PM.

MEKK-1, a component of the stress (stress-activated protein kinase/c-Jun N-terminal kinase) pathway, can selectively activate Smad2-mediated transcriptional activation in endothelial cells

Smad proteins are essential components of the intracellular signaling pathways utilized by members of the transforming growth factor-beta (TGF-beta) superfamily of growth factors. Certain Smad proteins (e.g. Smad1, -2, and -3) can act as regulated transcriptional activators, a process that involves phosphorylation of these proteins by activated TGF-beta superfamily receptors. We demonstrate that the intracellular kinase mitogen-activated protein kinase kinase kinase-1 (MEKK-1), an upstream activator of the stress-activated protein kinase/c-Jun N-terminal kinase pathway, can participate in Smad2-dependent transcriptional events in cultured endothelial cells. A constitutively active form of MEKK-1 but not mitogen-activated protein kinase kinase-1 (MEK-1) or TGF-beta-activated kinase-1, two distinct intracellular kinases, can specifically activate a Gal4-Smad2 fusion protein, and this effect correlates with an increase in the phosphorylation state of the Smad2 protein. These effects do not require the presence of the C-terminal SSXS motif of Smad2 that is the site of TGF-beta type 1 receptor-mediated phosphorylation. Activation of Smad2 by active MEKK-1 results in enhanced Smad2-Smad4 interactions, nuclear localization of Smad2 and Smad4, and the stimulation of Smad protein-transcriptional coactivator interactions in endothelial cells. Overexpression of Smad7 can inhibit the MEKK-1-mediated stimulation of Smad2 transcriptional activity. A physiological level of fluid shear stress, a known activator of endogenous MEKK-1 activity in endothelial cells, can stimulate Smad2-mediated transcriptional activity. These data demonstrate a novel mechanism for activation of Smad protein-mediated signaling in endothelial cells and suggest that Smad2 may act as an integrator of diverse stimuli in these cells.

Organized cell swimming motions in Bacillus subtilis colonies: patterns of short-lived whirls and jets

The swimming motions of cells within Bacillus subtilis colonies, as well as the associated fluid flows, were analyzed from video films produced during colony growth and expansion on wet agar surfaces. Individual cells in very wet dense populations moved at rates between 76 and 116 microm/s. Swimming cells were organized into patterns of whirls, each approximately 1,000 microm2, and jets of about 95 by 12 microm. Whirls and jets were short-lived, lasting only about 0.25 s. Patterns within given areas constantly repeated with a periodicity of approximately 1 s. Whirls of a given direction became disorganized and then re-formed, usually into whirls moving in the opposite direction. Pattern elements were also organized with respect to one another in the colony. Neighboring whirls usually turned in opposite directions. This correlation decreased as a function of distance between whirls. Fluid flows associated with whirls and jets were measured by observing the movement of marker latex spheres added to colonies. The average velocity of markers traveling in whirls was 19 microm/s, whereas those traveling in jets moved at 27 microm/s. The paths followed by markers were aligned with the direction of cell motion, suggesting that cells create flows moving with them into whirls and along jets. When colonies became dry, swimming motions ceased except in regions close to the periphery and in isolated islands where cells traveled in slow whirls at about 4 microm/s. The addition of water resulted in immediate though transient rapid swimming (> 80 microm/s) in characteristic whirl and jet patterns. The rate of swimming decreased to 13 microm/s within 2 min, however, as the water diffused into the agar. Organized swimming patterns were nevertheless preserved throughout this period. These findings show that cell swimming in colonies is highly organized.

Human prostaglandin transporter gene (hPGT) is regulated by fluid mechanical stimuli in cultured endothelial cells and expressed in vascular endothelium in vivo

BACKGROUND

biomechanical forces generated by blood flow within the cardiovascular system have been proposed as important modulators of regional endothelial phenotype and function. This process is thought to involve the regulation of vascular gene expression by physiological fluid mechanical stimuli such as fluid shear stresses.

METHODS AND RESULTS

We demonstrate sustained upregulation of a recently identified gene encoding a human prostaglandin transporter (hPGT) in cultured human vascular endothelium exposed to a physiological fluid mechanical stimulus in vitro. This biomechanical induction is selective in that steady laminar shear stress is sufficient to upregulate the hPGT gene at the level of transcriptional activation, whereas a comparable level of turbulent shear stress (a nonphysiological stimulus) is not. Various biochemical stimuli, such as bacterial endotoxin and the inflammatory cytokines recombinant human interleukin 1beta cytokines (rhIL-1beta) and tumor necrosis factor-alpha (TNF-alpha), did not significantly induce hPGT. Using a specific antiserum to hPGT, we demonstrate endothelial expression within the arterial vasculature and the microcirculation of highly vascularized tissues such as the heart.

CONCLUSIONS

Our results identify hPGT as an inducible gene in vascular endothelium and suggest that biomechanical stimuli generated by blood flow in vivo may be important determinants of hPGT expression. Furthermore, this demonstration of regulated endothelial expression of hPGT implicates this molecule in the regional metabolism of prostanoids within the cardiovascular system.

Cardiovascular effects of ozone exposure in human volunteers

We hypothesized that ozone (O3) exposure acutely affects cardiovascular hemodynamics in humans and, in particular, in subjects with essential hypertension. We studied 10 nonmedicated hypertensive and six healthy male adults. Each subject, after catheterization of the right heart and a radial artery, was exposed in an environmentally controlled chamber to filtered air (FA) on one day and to 0.3 ppm O3 on the following day for 3 h with intermittent exercise. Relative to FA exposure, O3 exposure induced no statistically significant changes in cardiac index, ventricular performance, pulmonary artery pressure, pulmonary and systemic vascular resistances, ECG, serum cardiac enzymes, plasma catecholamines and atrial natriuretic factor, and SaO2. The overall results did not indicate major acute cardiovascular effects of O3 in either the hypertensive or the control subjects. However, mean preexposure to postexposure changes were significantly (p < 0.02) larger with O3 than with FA for rate-pressure product (1,353 beats/min/mm Hg) and for heart rate (8 beats/min); these responses were not significantly different between the hypertensive and the control subjects. Significant O3 effects were also observed for mean FEV1 (-6%), and AaPO2 (> 10 mm Hg increase), which were not significantly different between the two groups. These results suggest that O3 exposure can increase myocardial work and impair pulmonary gas exchange to a degree that might be clinically important in persons with significant preexisting cardiovascular impairment, with or without concomitant lung disease.

Endoscopic management of complete obstruction of a ureteroneocystostomy in an infant

We present the case of an 18-month-old female who, after bilateral ureteroneocystostomies, developed complete obstruction at the left ureteroneocystostomy site. Using endourologic techniques, patency of the ureteroneocystostomy was re-established and has remained unobstructed during her 4-year follow-up.

The value of unenhanced helical computerized tomography in the management of acute flank pain

PURPOSE

We developed an algorithm using unenhanced computerized tomography (CT) for the management of acute flank pain and suspected ureteral obstruction.

MATERIALS AND METHODS

During a 25-month interval 417 patients with acute flank pain underwent unenhanced helical CT. The final diagnosis was confirmed by additional imaging or clinical followup. For all patients who underwent additional imaging studies the official dictated radiology reports were used to determine whether the studies were recommended based on CT findings. Cases requiring intervention were evaluated to determine whether additional imaging was performed before the procedure. Medical records were reviewed and/or patients were interviewed to document the course of therapy and long-term outcome.

RESULTS

Unenhanced helical CT diagnosed ureteral stone disease with 95% sensitivity, 98% specificity and 97% accuracy. Of the 38 patients requiring intervention, including nephrostomy catheters in 18, lithotripsy in 3 and ureteroscopic stone extraction in 7, additional imaging (excretory urography) was performed in only 1. Additional imaging studies generated by CT were done in 3 cases in which the dictated reports were indeterminate for ureteral stones, including negative excretory urography in 2 and retrograde urography in 1. In 1 patient in whom CT misdiagnosed a ureteral stone unnecessary retrograde urography revealed the calcification to be a gonadal vein phlebolith. Seven patients with false-negative examinations reported spontaneous stone passage with no complications.

CONCLUSIONS

Unenhanced helical CT accurately determines the presence or absence of ureterolithiasis in patients with acute flank pain. CT precisely identifies stone size and location. When ureterolithiasis is absent, other causes of acute flank pain can be identified. In most cases additional imaging is not required.

Egr-1 is activated in endothelial cells exposed to fluid shear stress and interacts with a novel shear-stress-response element in the PDGF A-chain promoter

Exposure of vascular endothelial cells to fluid mechanical forces can modulate the expression of many genes involved in vascular physiology and pathophysiology. Here, we report that platelet-derived growth factor (PDGF) A-chain gene expression is induced at the level of transcription in cultured bovine aortic endothelial cells exposed to a physiologic level of steady laminar shear stress (10 dyn/cm2). 5' Deletion analysis of the human PDGF-A promoter revealed that a GC-rich region near the TATA box was required for shear-inducible reporter gene expression. This element conferred shear inducibility onto a heterologous promoter-reporter construct that was otherwise unresponsive to shear stress. The induction of PDGF-A expression by shear was preceded by rapid and transient induction in the expression of the immediate-early gene, egr-1, which binds to GC-rich sequences. Gel shift studies indicated that shear-induced Egr-1 bound to the proximal PDGF-A promoter in a specific and time-dependent manner, displacing Sp1 from their overlapping recognition elements. Overlapping consensus binding sites for Egr-1 and Sp1 also appear in the proximal promoters of several other endothelial genes, including transforming growth factor-beta 1 and tissue factor, whose expression is modulated by shear stress. These findings define the Egr-1 binding site in the proximal PDGF-A promoter as a shear-stress-responsive element and suggest that shear-stimulated Egr-1 gene expression may be a unifying theme in the induction of various other endothelial genes exposed to biomechanical forces.

Vascular MADs: two novel MAD-related genes selectively inducible by flow in human vascular endothelium

Vascular endothelium is an important transducer and integrator of both humoral and biomechanical stimuli within the cardiovascular system. Utilizing a differential display approach, we have identified two genes, Smad6 and Smad7, encoding members of the MAD-related family of molecules, selectively induced in cultured human vascular endothelial cells by steady laminar shear stress, a physiologic fluid mechanical stimulus. MAD-related proteins are a recently identified family of intracellular proteins that are thought to be essential components in the signaling pathways of the serine/threonine kinase receptors of the transforming growth factor beta superfamily. Smad6 and Smad7 possess unique structural features (compared with previously described MADs), and they can physically interact with each other, and, in the case of Smad6, with other known human MAD species, in endothelial cells. Transient expression of Smad6 or Smad7 in vascular endothelial cells inhibits the activation of a transfected reporter gene in response to both TGF-beta and fluid mechanical stimulation. Both Smad6 and Smad7 exhibit a selective pattern of expression in human vascular endothelium in vivo as detected by immunohistochemistry and in situ hybridization. Thus, Smad6 and Smad7 constitute a novel class of MAD-related proteins, termed vascular MADs, that are induced by fluid mechanical forces and can modulate gene expression in response to both humoral and biomechanical stimulation in vascular endothelium.

Expression of the bumetanide-sensitive Na-K-Cl cotransporter BSC2 is differentially regulated by fluid mechanical and inflammatory cytokine stimuli in vascular endothelium

In vascular endothelium, the electroneutral Na-K-Cl cotransport system is thought to function in the maintenance of a selective permeability barrier in certain vascular beds (e.g., brain), as well as in the preservation of endothelial homeostasis in the face of fluctuating osmotic conditions that may accompany certain pathophysiological conditions (e.g., diabetes mellitus). Here we demonstrate that the gene encoding the bumetanide-sensitive cotransporter BSC2, one of the two major isoforms of Na-K-Cl cotransporters present in mammalian cells, can be differentially regulated by inflammatory cytokines and fluid mechanical forces in cultured endothelium. Interleukin-1beta and tumor necrosis factor-alpha significantly upregulate expression of BSC2 mRNA and protein in human umbilical vein endothelial cells, a response that is inhibited by pretreatment with interferon-gamma. Steady laminar fluid shear stress, at a physiologic magnitude (10 dyn/cm2), is also able to induce and maintain elevated expression of BSC2 in cultured human umbilical vein endothelial cells, while a comparable time-averaged magnitude of turbulent fluid shear stress is not. In vivo, BSC2 mRNA is upregulated after intraperitoneal administration of bacterial endotoxin (LPS) in murine lung and kidney, but not in cardiac tissue. These results provide the first experimental evidence that the BSC2 gene can be selectively regulated by different inflammatory cytokine and fluid mechanical stimuli in endothelium, and support a role for BSC2 in vascular homeostasis and inflammation.

Chamber exposures of children to mixed ozone, sulfur dioxide, and sulfuric acid

To help assess acute health effects of summer air pollution in the eastern United States, we simulated ambient "acid summer haze" as closely as was practical in a laboratory chamber. We exposed young volunteers who were thought to be sensitive to this pollutant mixture on the basis of previous epidemiologic evidence. Specifically, we exposed 41 subjects aged 9-12 y to mixed ozone (0.10 ppm), sulfur dioxide (0.10 ppm), and 0.6-microm sulfuric acid aerosol (100 +/- 40 microg/m3, mean +/- standard deviation) for 4 h, during which there was intermittent exercise. Fifteen subjects were healthy, and 26 had allergy or mild asthma. The entire group responded nonsignificantly (p > .05) to pollution exposure (relative to clean air), as determined by spirometry, symptoms, and overall discomfort level during exercise. Subjects with allergy/asthma showed a positive association (p = .01) between symptoms and acid dose; in healthy subjects, that association was negative (p = .08). In these chamber-exposure studies, we noted less of an effect than was reported in previous epidemiologic studies of children exposed to ambient "acid summer haze."

Laparoscopic evaluation and management of a child with ambiguous genitalia, ectopic spleen, and Meckel's diverticulum

Laparoscopy may be helpful in the evaluation and management of the child with intersex. Laparoscopic excision of dysgenetic gonads may be necessary due to the increased risk of malignancy. Residual müllerian duct structures are removed to prevent symptomatic complications at puberty. We present the case of a laparoscopic evaluation and management of a 46XY child with ambiguous genitalia, as well as the laparoscopic management of two unrelated anomalies discovered at the time of surgery.

Revised antitrust guidelines. Forming physician network joint ventures

What do physician executives need to know about antitrust guidelines? This article presents an overview of the revised "Statements of Antitrust Enforcement Policy in the Health Care Area," released in late 1996. Antitrust concepts and implicated federal statutes are described, and implications for forming physician network joint ventures are explored. Requirements of the revised standards used by the agencies to determine a permissible integration are addressed, as well as the factors considered in antitrust scrutiny of physician ventures.

Responses of older men with and without chronic obstructive pulmonary disease to prolonged ozone exposure

We tested responses to ozone (O3) under simulated "worst-case" ambient exposure conditions. Subjects included 9 men who had severe chronic obstructive pulmonary disease (COPD) with subnormal carbon monoxide diffusing capacity (i.e., an emphysemic component) and 10 age-matched healthy men. Each subject was exposed to 0.24 ppm O3 and to clean air (control) in an environmentally controlled chamber at 24 degrees C and 40% relative humidity. Exposures were randomized, they occurred 1 wk apart, and they lasted 4 h. During each half-hour interval, light exercise occurred (i.e., average ventilation 20 l/min) for 15 min. During both control and O3 exposures, group mean symptom intensity and specific airway resistance (SRaw) increased, whereas forced expiratory performance decreased. The healthy subgroup's mean arterial oxygen saturation (SaO2) rose slightly, and the COPD subgroup's mean SaO2 declined slightly, during exercise. Group mean forced expiratory volume in 1 s (FEV1.0) declined significantly in O3 exposures, compared with controls (p approximately .01). Mean excess FEV1.0 loss after 4 h in O3 (relative to control) was 8% of the preexposure value in the COPD subgroup, compared with 3% in the healthy subgroup (p > .05 [nonsignificant]). Overall FEV1.0 loss during O3 exposures, including exercise effects, averaged 19% in the COPD subgroup, compared with 2% in the healthy subgroup (p < .001). Symptoms, SRaw, and SaO2 responses, as well as healthy subjects' postexposure bronchial reactivity, differed little between O3-exposed and control subjects. We therefore concluded that in older men with or without severe COPD, O3 causes lung dysfunction under "worst-case" ambient exposure conditions, despite older subjects' comparative unresponsiveness to O3. The combined effect of O3 and exercise on lung dysfunction is markedly greater with COPD. It is still unclear whether COPD causes an increased response to O3 per se.

Effect of inhaled salmeterol on sulfur dioxide-induced bronchoconstriction in asthmatic subjects

This study tested the capability of a single 42-microgram dose of inhaled salmeterol xinafoate, a long-acting beta 2-agonist, to protect against bronchoconstrictive effects of exposure to 0.75 ppm sulfur dioxide (SO2) during exercise, for up to 24 h. Ten SO2-responsive adult volunteers with stable asthma were studied under 4 conditions of drug pretreatment/exposure, administered in random order, double-blind: salmeterol/SO2, placebo/SO2, salmeterol/clean air, and placebo/clean air. Each subject underwent 10-min exposure/exercise challenges in a chamber 1, 12, 18, and 24 h after pretreatment. Exercise ventilation rates averaged 29 L/min. Response was measured as the decrement in FEV1 between preexposure and postexposure (lowest value within 30 min). After salmeterol, mean decrement post-SO2 was 7% at 1 h and 12% at 12 h. At 18 and 24 h after salmeterol, and at all times after placebo, mean decrements were 25 to 30%. After 18 and 24 h, salmeterol still improved base-line FEV1 relative to placebo, although improvement was not statistically significant at 24 h. Acute symptom increases accompanied FEV1 decrements.

CONCLUSION

In our asthmatic subjects, pretreatment with salmeterol imparted clinically and statistically significant (p < 0.01) protection against bronchoconstriction induced by SO2/exercise for at least 12 h, and maintained an improvement in lung function for as much as 18 h.

Short-term air pollution exposures and responses in Los Angeles area schoolchildren

We studied 269 school children from three Southern California communities of contrasting air quality in two successive school years, to investigate short-term effects of ambient ozone (O3), nitrogen dioxide (NO2), or particulate matter (PM) on respiratory health. We measured lung function and symptoms twice daily for one week each in fall, winter and spring; and concurrently assessed time-activity patterns and personal exposures. Average daily personal exposures correlated with pollutant concentrations at central sites (r = 0.61 for O3, 0.63 for NO2, 0.48 for PM). Questionnaire-reported outdoor activity increased slightly in communities/seasons with higher pollution. Lung function differences between communities were explainable by age differences. Morning forced vital capacity (FVC) decreased significantly with increase in PM or NO2 measured over the preceding 24 hours. Morning-to-afternoon change of forced expired volume in one second (FEV1) became significantly more negative with increase in PM, NO2, or O3 on the same day. Predicted FVC or FEV1 loss on highest- vs lowest-pollution days was < 2%. Daily symptoms showed no association with current or prior 24-hour pollution, but increased with decreasing temperature. Parents' questionnaire responses suggested excess asthma and allergy in children from one polluted community while children in the other polluted community reported more symptoms, relative to the cleaner community. We conclude that Los Angeles area children may experience slight lung function changes in association with day-to-day air quality changes, reasonably similar to responses seen by others in less polluted areas. Although short-term pollution effects appear small, they should be assessed in longitudinal lung function studies when possible, to allow maximally accurate measurement of longer-term function changes.

Physiology and evaluation of ureteropelvic junction obstruction

Ureteropelvic junction (UPJ) obstruction is not a single anatomic entity but rather a set of processes with multiple causes. In the obstructed system, histologic changes are apparent that have implications for healing. The role of crossing vessels In UPJ obstruction and its treatment is of growing interest. Various methods are available to assess the functional characteristics of the UPJ, of which the diuretic renogram, Whitaker perfusion test, and Doppler ultrasound resistive index may be the most useful. The treatment must be individualized according to the patient's symptoms, the status of renal function, and the potential complications of intervention.

Exposures of health-care workers to ribavirin aerosol: a pharmacokinetic study

We assessed health risks to nurses and therapists exposed occupationally to ribavirin aerosol, a known rodent teratogen, by measuring uptake as a function of exposure concentration. During a 4-d period, healthy, nonsmoking, young adult volunteers (N = 14) were exposed 4 h/d respirable ribavirin aerosol at concentrations that exceeded occupational levels. Intermittent exercise occurred during exposure, and all activities occurred in a simulated hospital room. Ribavirin was assayed in plasma, red cells, and urine; lung function and symptoms were also measured. In 7 volunteers who were exposed to 30 mg/m3 (i.e., received approximately 10% of therapeutic dose), postexposure ribavirin concentrations in plasma and urine were similar on all 4 d, averaging (0.89 mumol/l and 131 mumol/l, respectively. These concentrations decreased after exposure, with half-times of 37-39 h. Red-cell concentrations averaged 31 mumol/l on d 4, accounting for < 5% of inhaled ribavirin mass, and they remained stable for 4 d afterward. In 7 volunteers exposed to 3 mg/m3 (i.e., approximately 1% of therapeutic dose), plasma averaged 0.075 mumol/l and red cells averaged 3 mumol/l on d 4 (i.e., near detection limits). Small variations occurred in lung function, reported symptoms, and hematologic values for exposures to both 3 and 30 microgram/m3; therefore, these effects were most likely not caused by ribavirin. Typical occupational exposures to ribavirin, without recommended protective measures, should result in undetectable or barely detectable body burdens, i.e., approximately 0.1%-1% of levels reported to be toxic to laboratory animals.

Laparoscopic assisted continent urinary diversion in the pig

PURPOSE

The ideal urinary reservoir would be low pressure, nonrefluxing and simple to construct. Hohenfellner recently described creating an in situ ureterosigmoidostomy with a 5 to 6 cm. detubularized portion of sigmoid colon and rectum (sigmoid-rectum pouch). In an effort to further study the reconstructive applications of laparoscopy, we sought to laparoscopically create a sigmoid-rectum pouch in an animal model. In addition, we sought to compare a "dunked" (right ureter) with a hand-sewn end-to-side ureterocolonic anastomosis (left ureter).

MATERIALS AND METHODS

Nine male domestic pigs underwent laparoscopic creation of a continent urinary diversion. Pouch creation and the ureterocolonic anastomoses were done extracorporeally; ureteral stents were not used. Average operative time was 122 minutes. Eight pigs survived the 10 to 12 week study period.

RESULTS

Mean pouch capacity was 360 cc and pouch pressure remained < 20 cm.H2O. Stones were noted on the bowel staple line in 44% of the animals. Ureterocolonic obstruction occurred in 11% of the right ureters and 33% of the left ureters.

CONCLUSIONS

A laparoscopically created continent sigmoid-rectum diversion appears to be feasible. A "dunked" ureterocolonic anastomosis provides equivalent or better drainage than a traditional hand-sewn ureterocolonic anastomosis. Problems with stone formation on the titanium staple line need to be resolved.

Controlled exposures of young asthmatics to mixed oxidant gases and acid aerosol

To help assess short-term respiratory responses to summertime air pollution, we exposed 24 asthmatic volunteers aged 11-18 in a chamber to respirable acid aerosol (mass median aerodynamic diameter 0.66 micron) plus 0.3 ppm nitrogen dioxide (NO2) plus 0.2 ppm ozone (O3). The aerosol contained available hydrogen ions (H-) at an average concentration of 2.6 mumol/m-, equivalent to 127 micrograms/m3 sulfuric acid (H2SO4); some H+ probably was in NH4HSO4 rather than H2SO4. The volunteers were exposed separately to O3/NO2 without acid and to clean air. Exposures lasted 90 min, including three 15-min exercise sessions with ventilation averaging 32 L/min, at 21 degrees C and 50% relative humidity. Asthma medications were withheld before and during exposures. Subjects gargled lemonade to minimize acid neutralization by oral ammonia (NH3). Exercise-induced bronchospasm was evident in all exposures. Differences in group mean lung function response among H2SO4/O3/NO2, O3/NO2, and clean-air exposures were not statistically significant. Individuals' measured oral NH3 concentrations or estimated inhaled doses of H2SO4 did not significantly predict their lung function changes. A few subjects showed unfavorable function changes during pollutant exposures, which might be chance occurrences or might indicate the existence of an acid-pollution-susceptible subgroup among young asthmatic subjects.

Laparoscopic pneumodissection: a unique means of tissue dissection

PURPOSE

To study the acute and chronic tissue effects of using high pressure CO2 to dissect tissues during laparoscopic procedures.

MATERIALS AND METHODS

A 5-mm. laparoscopic pneumodissector, capable of delivering brief bursts of high pressure CO2 (20 to 100 psi), was discharged on a variety of porcine tissues including the renal hilum. Acute and chronic histological sections, intraoperative blood gases and perioperative renal scans were obtained.

RESULTS

The only tissue with significant acute damage was the spleen. Acute changes in other tissues were minimal; long-term studies revealed no discernible damage to these same tissues. Intraoperative blood gases revealed no significant changes in the serum pCO2 or pH. Likewise, there was no renal damage discernible by renal scans.

CONCLUSIONS

Pneumodissection at 50 psi is a safe method for dissecting the porcine kidney and the vessels of the renal hilum. Clinical studies are pending.

Effect of piezoelectric energy on porcine kidneys using the EDAP LT.02

EDAP International (Cambridge, Massachusetts) has developed a new piezoelectric lithotripter (LT.02) that differs from their earlier model (LT.01) in two important respects: method of stone visualization and available power. The LT.02 provides both in-line fluoroscopy as well as real time ultrasound. The maximum energy is 1400 Bar (compared with 1100 Bar in the LT.01). The purpose of this study was to determine whether treatment with the EDAP LT.02 piezoelectric lithotripter would cause significant renal injury in minipigs. Accordingly, 18 minipigs were divided into 3 groups of 6. Each group received a treatment of 20, 40 or 60 minutes; the power level and shock wave frequency were kept at maximal levels throughout the treatment period. Three pigs from each group were sacrificed at 72 hours (acute). The remaining 9 pigs were sacrificed 1 month following LT.02 treatment (chronic). Histopathologic analysis of the treated kidney revealed that 33% of the 9 acute pigs developed a small capsular hematoma, whereas 66% showed only a small parenchymal contusion ( < or = 1% of total renal volume). Among the chronic pigs, 66% had a small cortical scar, whereas 33% had no macroscopic pathology. Despite the differences in the number of shock waves delivered, these changes were evenly distributed among the 3 groups. Histologic acute changes included circumscribed areas of hemorrhagic infarction, vascular thrombosis with recanalization and focal tubular obstruction and damage. At 30 days, however, these acute injuries had completely resolved in 3 pigs and were only notable as minute areas of focal tubular loss in 6 pigs.

Effects of prolonged, repeated exposure to ozone, sulfuric acid, and their combination in healthy and asthmatic volunteers

To evaluate effects of "acid summer haze" on individuals who exercise extensively outdoors, we exposed 45 adult volunteers (15 normal or atopic, 30 asthmatic) in a chamber to a mixture of 0.12 ppm ozone (O3) and approximately 100 micrograms/m3 of respirable sulfuric acid aerosol (H2SO4). On separate occasions we exposed the same subjects to O3 alone, to H2SO4 alone, and to clean air. In exposures involving H2SO4, excess acid was generated to consume ammonia released by the subjects, and the aerosol therefore contained ammonium salts in addition to H2SO4. Subjects were exposed to each atmosphere on two successive days, for 6.5 h/d, with six 50-min exercise periods at ventilation rates averaging 29 L/min. Exposures were conducted during four successive weeks, in random order. Lung function and symptoms were measured before exposure and hourly during exposure. Bronchial reactivity to inhaled methacholine was measured just after the end of each exposure. Exposure to H2SO4 alone caused no significant changes in lung function, symptoms, or bronchial reactivity relative to clean air. Exposure to O3 alone or O3 + H2SO4 caused a progressive, statistically significant (p < 0.05) decline in forced expiratory function, smaller on the second day than the first, as previously found by others for O3 exposure. Bronchial reactivity increased significantly after exposure to O3 with or without H2SO4. Changes in mean lung function and bronchial reactivity with O3 + H2SO4 exposure were modestly larger than changes with O3 exposure, but the differences were nonsignificant or marginally significant. A minority of individual asthmatic and nonasthmatic subjects showed substantially greater declines in function with exposure to O3 + H2SO4 relative to O3 alone. Repeat exposure studies of these subjects again showed an excess response to O3 + H2SO4 on the average, but there was no significant correlation between the excess responses of individual subjects in the original and repeat studies. We conclude that for typical healthy or asthmatic adults heavily exposed to acid summer haze, O3 is more important than H2SO4 as a cause of short-term respiratory irritant effects.