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Key Points RUNX1 reduces cell cycle and immediate early gene expression in naive B cells.BCR stimulation triggers a switch from RUNX1 to RUNX3 binding at cell cycle genes.Notch signaling is downregulated by RUNX1 in follicular B cells., RUNX1 is a transcription factor that plays key roles in hematopoietic development and in hematopoiesis and lymphopoiesis. In this article, we report that RUNX1 regulates a gene expression program in naive mouse B cells that affects the dynamics of cell cycle entry in response to stimulation of the BCR. Conditional knockout of Runx1 in mouse resting B cells resulted in accelerated entry into S-phase after BCR engagement. Our results indicate that Runx1 regulates the cyclin D2 (Ccnd2) gene, the immediate early genes Fosl2, Atf3, and Egr2, and the Notch pathway gene Rbpj in mouse B cells, reducing the rate at which transcription of these genes increases after BCR stimulation. RUNX1 interacts with the chromatin remodeler SNF-2–related CREB-binding protein activator protein (SRCAP), recruiting it to promoter and enhancer regions of the Ccnd2 gene. BCR-mediated activation triggers switching between binding of RUNX1 and its paralog RUNX3 and between SRCAP and the switch/SNF remodeling complex member BRG1. Binding of BRG1 is increased at the Ccnd2 and Rbpj promoters in the Runx1 knockout cells after BCR stimulation. We also find that RUNX1 exerts positive or negative effects on a number of genes that affect the activation response of mouse resting B cells. These include Cd22 and Bank1, which act as negative regulators of the BCR, and the IFN receptor subunit gene Ifnar1. The hyperresponsiveness of the Runx1 knockout B cells to BCR stimulation and its role in regulating genes that are associated with immune regulation suggest that RUNX1 could be involved in regulating B cell tolerance.

The regenerative potential of mammalian peripheral nervous system (PNS) neurons after injury is critically limited by their slow axonal regenerative rate1. Since a delayed target re-innervation leads to irreversible loss of function of target organs2, accelerated axonal regeneration is required to enhance functional outcomes following injury. Regenerative ability is influenced by both injury-dependent and injury-independent mechanisms3. Among the latter, environmental factors such as exercise and environmental enrichment have been shown to affect signalling pathways that promote axonal regeneration4. Several of these pathways, including modifications in gene transcription and protein synthesis, mitochondrial metabolism and release of neurotrophins, can be activated by intermittent fasting (IF)5,6. IF has in turn been shown to increase synaptic plasticity7,8 and neurogenesis9, partially sharing molecular mechanisms with axonal regeneration. However, whether IF influences the axonal regenerative ability remains to be investigated. Here we show that IF promotes axonal regeneration after sciatic nerve crush in the mouse via an unexpected mechanism that relies upon the gram + gut microbiome and an increase of the gut bacteria-derived metabolite indole-3-propionic acid (IPA) in the serum. IPA production by Clostridium sporogenes is required for efficient axonal regeneration, and delivery of IPA after sciatic injury significantly enhances axonal regeneration, accelerating recovery of sensory function. Mechanistically, RNA sequencing analysis from sciatic dorsal root ganglia suggested a role for neutrophil chemotaxis in the IPA-dependent regenerative phenotype that was confirmed by the inhibition of neutrophil chemotaxis. Our results demonstrate for the first time the ability of a microbiome derived metabolite, such as IPA, in facilitating regeneration and functional recovery of sensory axons via an immune-mediated mechanism. Since IPA is a naturally occurring metabolite with a very favourable toxicity profile, it represents a realistic translational possibility for human axonal injuries.

The regenerative potential of mammalian peripheral nervous system neurons after injury is critically limited by their slow axonal regenerative rate

RUNX1 is a transcription factor that plays key roles in haematopoietic development and in adult haematopoiesis and lymphopoiesis. Here we report that RUNX1 is also involved in controlling the dynamics of cell cycle entry of naïve resting B cells in response to stimulation of the B cell receptor (BCR). Conditional knockout ofRunx1in mouse resting B cells resulted in accelerated entry of the cells into S-phase following BCR engagement. Our results indicate that Runx1 regulates the cyclin D2 (Ccnd2) gene, the immediate early genes,Fosl2,Atf3andEgr2, and the Notch effectorRbpj, in B cells, reducing the rate at which transcription of these genes increases following BCR stimulation. RUNX1 interacts with the chromatin remodeller SRCAP, recruiting it to promoter and enhancer regions of theCcnd2gene. BCR-mediated activation triggers switching between binding of RUNX1 and its paralog RUNX3 and between SRCAP and the SWI/SNF remodelling complex member BRG1. We also find that RUNX1 regulates expression of a number of immunomodulatory genes in resting B cells. These include the interferon receptor subunit geneIfnar1, which is upregulated in B cells from lupus patients, thePtpn22gene, which has been identified as a major lupus risk allele, and theLrrk2gene, which is mutated in familial Parkinson’s disease. The hyperresponsiveness of theRunx1knockout B cells to antigen stimulation and its role in regulating a suite of genes that are known to be associated with autoimmune disease suggest that RUNX1 is a major regulator of B cell tolerance and autoimmunity.

IgE is the least abundant circulating antibody class but is constitutively present in healthy tissues bound to resident cells via its high-affinity receptor, FcεRI. The physiological role of endogenous IgE is unclear but it is suggested to provide host protection against a variety of noxious environmental substances and parasitic infections at epithelial barrier surfaces. Here we show that skin inflammation enhances levels of IgE with natural specificities and with a similar repertoire, VDJ rearrangements and CDRH3 characteristics as in healthy tissue. IgE-bearing basophils are recruited to inflamed skin via CXCL12 and TSLP/IL-3-dependent upregulation of CXCR4. In the inflamed skin, IgE/FcεRI-signalling in basophils promotes epithelial cell growth and differentiation, partly through histamine engagement of H1R and H4R. Furthermore, this natural IgE response strongly drives tumour outgrowth of epithelial cells harbouring oncogenic mutation. These findings indicate that natural IgE support skin barrier defences however during chronic tissue inflammation this may be subverted to promote tumour growth.

IgE is the least abundant circulating antibody class but is constitutively present in healthy tissues bound to resident cells via its high-affinity receptor, FcεRI. The physiological role of endogenous IgE antibodies is unclear but it has been suggested that they provide host protection against a variety of noxious environmental substances and parasitic infections at epithelial barrier surfaces. Here we show, in mice, that skin inflammation enhances levels of IgE antibodies that have natural specificities and a repertoire, VDJ rearrangements and CDRH3 characteristics similar to those of IgE antibodies in healthy tissue. IgE-bearing basophils are recruited to inflamed skin via CXCL12 and thymic stromal lymphopoietin (TSLP)/IL-3-dependent upregulation of CXCR4. In the inflamed skin, IgE/FcεRI-signalling in basophils promotes epithelial cell growth and differentiation, partly through histamine engagement of H1R and H4R. Furthermore, this IgE response strongly drives tumour outgrowth of epithelial cells harbouring oncogenic mutation. These findings indicate that natural IgE antibodies support skin barrier defences, but that during chronic tissue inflammation this role may be subverted to promote tumour growth.

IgE is an ancient and conserved immunoglobulin isotype with potent immunological function. Nevertheless, the regulation of IgE responses remains an enigma, and evidence of a role for IgE in host defense is limited. Here we report that topical exposure to a common environmental DNA-damaging xenobiotic initiated stress surveillance by γδTCR+ intraepithelial lymphocytes that resulted in class switching to IgE in B cells and the accumulation of autoreactive IgE. High-throughput antibody sequencing revealed that γδ T cells shaped the IgE repertoire by supporting specific variable-diversity-joining (VDJ) rearrangements with unique characteristics of the complementarity-determining region CDRH3. This endogenous IgE response, via the IgE receptor FceRI, provided protection against epithelial carcinogenesis, and expression of the gene encoding FceRI in human squamous-cell carcinoma correlated with good disease prognosis. These data indicate a joint role for immunosurveillance by T cells and by B cells in epithelial tissues and suggest that IgE is part of the host defense against epithelial damage and tumor development.

Complement is a CD8 + T cell metabolic rheostat Systemic lupus erythematosus (SLE) is associated with deficiencies in the complement protein C1q. Although C1q plays a role in the clearance of apoptotic cells, there are several redundant clearance pathways. Disruption of one pathway does not lead to an autoimmune defect. In a chronic graft-versus-host disease model of SLE, Ling et al. show that C1q dampens CD8 + T cell responses to self-antigens. C1q modulates metabolism through the mitochondrial cell-surface protein p32/gC1qR. The lack of C1q during a viral infection also enhances CD8 + T cell responses. Thus, C1q plays a role as a “metabolic rheostat” for effector CD8 + T cells. Science , this issue p. 558

Context . Low birth weight (LBW) is associated with infant morbidity and mortality. This is the first study of LBW in Kansas using vital statistics to determine maternal and health care system factors associated with LBW. Outcomes . Low birth weight. Objective . Determine if prenatal care, maternal socio-demographic or medical factors, or insurance status were associated with LBW. Methods . Birth certificate data were merged with Medicaid eligibility data and subjected to logistic regression analysis. Results . Of the 37,081 single vaginal births, LBW rates were 5.5% overall, 10.8% for African Americans, and 5% for White Americans. Lacking private insurance was associated with 34% more LBW infants (AOR 1.34; 95% CI 1.13–1.58), increased comorbidity, and late or less prenatal care. Low birth weight was associated with maternal medical comorbidity and with previous adverse birth outcomes. Conclusions . Insurance status, prenatal care, and maternal health during pregnancy are associated with LBW. Private insurance was consistently associated with more prenatal care and better outcomes. This study has important implications regarding health care reform.

The currents forced by wind stress near the critical latitude (30°N or 30°S) appear enhanced as a result of the combination of natural modes of ocean currents (e.g., near-inertial motions) and diurnal land/sea breeze-driven currents. Here we assess the wind-current transfer function, derived from observations of coastal surface currents and surface winds off the U.S. West Coast (32°N to 47°N), as a function of the latitude (alongshore direction) and frequency. We compare the transfer functions at the diurnal frequency derived from observations and two analytical models (e.g., the Ekman model and a near-surface averaged Ekman model). The amplitude of the data-derived transfer function decreases with increasing distance from the critical latitude, and its argument varies nearly within the range estimated from two analytical models. Our results confirm that the resonant wind-current responses near the critical latitude are 8 to 12 times stronger than the purely diurnal land/sea breeze-forced currents in other latitudes.

[1] The network comprising 61 high-frequency radar systems along the U.S. West Coast (USWC) provides a unique, high resolution, and broad scale view of ocean surface circulation. Subinertial alongshore surface currents show poleward propagating signals with phase speeds of O(10) and O(100–300) km d −1 that are consistent with historical in situ observations off the USWC and that can be possibly interpreted as coastally trapped waves (CTWs). The propagating signals in the slow mode are partly observed in southern California, which may result from scattering and reflection of higher-mode CTWs due to curvature of shoreline and bathymetry near Point Conception, California. On the other hand, considering the order of the phase speed in the slow mode, the poleward propagating signals may be attributed to alongshore advection or pressure-driven flows. A statistical regression of coastal winds at National Data Buoy Center buoys on the observed surface currents partitions locally and remotely wind-forced components, isolates footprints of the equatorward propagating storm events in winter off the USWC, and shows the poleward propagating signals year round.

Composition of salt marsh vegetation is important to wetland ecosystem health, and monitoring invasive species is critical. The purpose of this study was to examine the utility of airborne hyperspectral imagery in mapping salt marsh vegetation in Humboldt Bay, California, USA. An unmixing algorithm was applied to spatial and spectral image subsets. Overall accuracy among Spartina densiflora, Salicornia virginica, and Distichlis spicata was assessed at 85.1%. Algorithm prediction between observed and predicted percent cover ranged from r2 = 0.32 to r2 = 0.53, an improvement on comparable studies. Percent cover prediction was least accurate for Distichlis spicata, due to initial endmember selection. Use of the Pixel Purity Index in conjunction with field work likely aided in identifying the best candidates for the linear unmixing technique.

A coupled 1D physical-biological model of Crater Lake is presented. The model simulates the seasonal evolution of two functional phytoplankton groups, total chlorophyll, and zooplankton in good quantitative agreement with observations from a 10-year monitoring study. During the stratified period in summer and early fall the model displays a marked vertical structure: the phytoplankton biomass of the functional group 1, which represents diatoms and dinoflagellates, has its highest concentration in the upper 40 m; the phytoplankton biomass of group 2, which represents chlorophyta, chrysophyta, cryptomonads and cyanobacteria, has its highest concentrations between 50 and 80 m, and phytoplankton chlorophyll has its maximum at 120 m depth. A similar vertical structure is a reoccurring feature in the available data. In the model the key process allowing a vertical separation between biomass and chlorophyll is photoacclimation. Vertical light attenuation (i.e., water clarity) and the physiological ability of phytoplankton to increase their cellular chlorophyll-to-biomass ratio are ultimately determining the location of the chlorophyll maximum. The location of the particle maxima on the other hand is determined by the balance between growth and losses and occurs where growth and losses equal. The vertical particle flux simulated by our model agrees well with flux measurements from a sediment trap. This motivated us to revisit a previously published study by Dymond et al. (1996). Dymond et al. used a box model to estimate the vertical particle flux and found a discrepancy by a factor 2.5–10 between their model-derived flux and measured fluxes from a sediment trap. Their box model neglected the exchange flux of dissolved and suspended organic matter, which, as our model and available data suggests is significant for the vertical exchange of nitrogen. Adjustment of Dymond et al.’s assumptions to account for dissolved and suspended nitrogen yields a flux estimate that is consistent with sediment trap measurements and our model.

Zhang et al. show that DOCK8-deficient T and NK cells develop cell and nuclear shape abnormalities that do not impair chemotaxis but contribute to a form of cell death they term cytothripsis. Cytothripsis of DOCK8-deficient cells prevents the generation of long-lived skin-resident memory CD8 T cells resulting in impaired immune response to skin infection., DOCK8 mutations result in an inherited combined immunodeficiency characterized by increased susceptibility to skin and other infections. We show that when DOCK8-deficient T and NK cells migrate through confined spaces, they develop cell shape and nuclear deformation abnormalities that do not impair chemotaxis but contribute to a distinct form of catastrophic cell death we term cytothripsis. Such defects arise during lymphocyte migration in collagen-dense tissues when DOCK8, through CDC42 and p21-activated kinase (PAK), is unavailable to coordinate cytoskeletal structures. Cytothripsis of DOCK8-deficient cells prevents the generation of long-lived skin-resident memory CD8 T cells, which in turn impairs control of herpesvirus skin infections. Our results establish that DOCK8-regulated shape integrity of lymphocytes prevents cytothripsis and promotes antiviral immunity in the skin.

Data collected in Barrow Strait during April and May 1995 indicate that turbulence can occur throughout the water column, with the most energetic turbulence being associated with strong currents during spring tides. In the surface mixed layer (SML) under the first-year, land-fast ice, the average effective vertical diffusivity was proportional to current speed, with mean values ranging up to 0.02 m 2 s -1 . Current speeds in the SML during tidal maxima sometimes exceeded 20 cm s -1 but turbulent stress levels remained low because the ice undersurface was hydrodynamically smooth. An asymmetry observed in under surface drag during the tidal cycle is associated with changes in eddy viscosity, possibly in response to the advection of a horizontal salinity gradient in the SML in this region. In the sharp halocline ( N ≈15–20 cycles h -1 ) at the base of the SML, mixing was often too weak to transport heat, salt, and other scalars vertically. During such periods the halocline acts as a barrier to the transport of properties, such as nutrients, from the deeper water to the surface. Within the deeper, less-stratified, water ( N ≈3–5 cycles h -1 ), energetic mixing frequently occurred, and was modulated by both the spring/neap tidal variability and within each tidal cycle. The water column was, on average, fresher than observed in previous spring measurements from this area, suggesting interannual variability in the Archipelago hydrography.

BACKGROUND: Motor vehicle collisions (MVCs) are the second leading cause of injury among octogenarians. Physicians and families lack outcomes-based data to assist in the decision-making process concerning injury treatment in this population. The purpose of this study was to evaluate 1-year postdischarge mortality in octogenarian MVC patients, cause of death, and patterns predictive of mortality. METHODS: A 10-year retrospective review was conducted of trauma patients 80 years and older who were involved in an MVC and were subsequently discharged alive. Data collected included demographics, injury severity and patterns, hospitalization details, and outcomes. State death database and hospital records were queried to determine cause of death for patients who died within 12 months of hospital discharge. Analyses were conducted to explore if a relationship existed between severity of injury and injury patterns to 12-month postdischarge mortality. RESULTS: Among the 199 patients included in this study, mean (SD) age and Injury Severity Score (ISS) was 84.2 (3.3) years and 9.3 (8.2), respectively. Twenty-two patients (11.1%) died within 12 months. Among these patients, cause of death was directly related to trauma in nine (40.9%), likely related to trauma in seven (31.8%), and unrelated to trauma in six (27.3%). More severely injured patients (ISS >15, p = 0.0041) and those admitted to the intensive care unit (ICU) (p = 0.0051) were more likely to die within 12 months of discharge. Results indicated a trend toward higher mortality in patients with pneumonia. Rib, hip, and pelvic fractures; spinal injuries; intubation upon hospital arrival; and need for mechanical ventilation were not associated with higher postdischarge mortality rates. CONCLUSION: The commonly held belief that the majority of octogenarians with MVC-related trauma die within 1 year of hospital discharge is refuted by this study. Only injury severity, ICU admission, and ICU duration were predictive of mortality within 12 months following discharge. LEVEL OF EVIDENCE: Prognostic study, level III. Language: en

Patients with the dedicator of cytokinesis 8 (DOCK8) immunodeficiency syndrome suffer from recurrent viral and bacterial infections, hyper-immunoglobulin E levels, eczema, and greater susceptibility to cancer. Because natural killer T (NKT) cells have been implicated in these diseases, we asked if these cells were affected by DOCK8 deficiency. Using a mouse model, we found that DOCK8 deficiency resulted in impaired NKT cell development, principally affecting the formation and survival of long-lived, differentiated NKT cells. In the thymus, DOCK8-deficient mice lack a terminally differentiated subset of NK1.1(+) NKT cells expressing the integrin CD103, whereas in the liver, DOCK8-deficient NKT cells express reduced levels of the prosurvival factor B-cell lymphoma 2 and the integrin lymphocyte function-associated antigen 1. Although the initial NKT cell response to antigen is intact in the absence of DOCK8, their ongoing proliferative and cytokine responses are impaired. Importantly, a similar defect in NKT cell numbers was detected in DOCK8-deficient humans, highlighting the relevance of the mouse model. In conclusion, our data demonstrate that DOCK8 is required for the development and survival of mature NKT cells, consistent with the idea that DOCK8 mediates survival signals within a specialized niche. Accordingly, impaired NKT cell numbers and function are likely to contribute to the susceptibility of DOCK8-deficient patients to recurrent infections and malignant disease.

With collaborated research efforts in the regional coastal ocean observing systems (SCCOOS, CeNCOOS, and NANOOS) off the U.S. West Coast (USWC), the nearly completed high-frequency radar (HFR) network provides an unprecedented capability to monitor and understand coastal ocean dynamics and phenomenology through hourly surface current measurements at up to 1 km resolution. The dynamics of the surface currents off the USWC are governed by tides, winds, Coriolis force, low-frequency pressure gradients (less than 0.4 cycles per day (cpd)), and nonlinear interactions of those forces. The HFR surface currents resolve coastal surface ocean variability continuously across scales from sub-mesoscale to mesoscale (O(1) km to O(1000) km). Their spectra decay with k-2 at high wave number (less than 100 km) in agreement with theoretical sub-mesoscale spectra below the observational limits of present-day satellite altimeters.

Deficiency in the guanine nucleotide exchange factor dedicator of cytokinesis 8 (DOCK8) causes a human immunodeficiency syndrome associated with recurrent sinopulmonary and viral infections. We have recently identified a DOCK8-deficient mouse strain, carrying an ethylnitrosourea-induced splice-site mutation that shows a failure to mature a humoral immune response due to the loss of germinal centre B cells. In this study, we turned to T-cell immunity to investigate further the human immunodeficiency syndrome and its association with decreased peripheral CD4 + and CD8 + T cells. Characterisation of the DOCK8-deficient mouse revealed T-cell lymphopenia, with increased T-cell turnover and decreased survival. Egress of mature CD4 + thymocytes was reduced with increased migration of these cells to the chemokine CXCL12. However, despite the two-fold reduction in peripheral naïve T cells, the DOCK8-deficient mice generated a normal primary CD8 + immune response and were able to survive acute influenza virus infection. The limiting effect of DOCK8 was in the normal survival of CD8 + memory T cells after infection. These findings help to explain why DOCK8-deficient patients are susceptible to recurrent infections and provide new insights into how T-cell memory is sustained. © 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim.

signals with phase speeds of O(10) and O(100 to 300) km day −1 and time scales of 2 to 3 weeks. The signals with slow phase speed are only observed in southern California. It is hypothesized that they are scattered and reflected by shoreline curvature and bathymetry change and do not penetrate north of Point Conception. The seasonal transition of alongshore surfacecirculationforcedbyupwelling‐favorablewindsandtheirrelaxationiscapturedinfine detail.Submesoscaleeddies,identifiedusingflowgeometry,haveRossbynumbersof0.1to3, diameters in the range of 10 to 60 km, and persistence for 2 to 12 days. The HFR surface currents resolve coastal surface ocean variability continuously across scales from

To investigate the connectivity between central California marine protected areas (MPAs), back-projections were calculated using the network of high-frequency (HF) radar ocean surface current mapping stations operated along the California coast by the member institutions of the Coastal Ocean Currents Monitoring Program with funding provided by California voters through Propositions 40 & 50 and administered by the State Coastal Conservancy. Trajectories of 1 km resolution grids of water particles were back-projected from ten MPAs each hour, out through 40 days in the past, from each day in 2008, producing a map of where surface waters travel over a 40-day period to reach the MPAs — and visualizations of the length of time the waters travel along these paths. By comparing the travel times of those back-projected track-points that crossed between MPA regions, the connection time between MPAs along the State's central coast was assessed. Repeating these calculations resulted in a connectivity matrix between the MPAs in the region, and may be useful for assessing connectivity for the important invertebrate and fish larvae that are restricted to the surface ocean during a fraction of their lifecycle.

Melbourne:Therapeutic Guidelines Limited; 2005.369 pages. Price: $39, students $30, plus postage

“Water filled view of balloon dilation”—a new technique, to enhance the visualization of esophageal stricture dilation

Introduction/Aim: Management options for PCES following HN 2M & 3F) underwent endoscopic dilation of PCES following H&N cancer treatment. The following protocol to access PCES for endoscopic dilation was used in a stepwise approach (Step 1,2,3). Endoscopic dilation techniques: 1) Antegrade dilation-Conventional technique: In 3 patients, wire guided endoscopic dilation with Savary dilators was performed under conscious sedation. Dilation to 15 mm was achieved in 4 wks. 2) Antegrade dilation- Laryngeal Jack assisted technique: In a 57 yr. female, the stricture opening could not be identified at endoscopy. A novel approach, the Laryngeal Jack technique (elevation of the larynx from the posterior pharyngeal wall and maintaining the position with a Dedo laryngoscope suspended in a stabilizer) was used to identify the opening of the PCES under general anesthesia with the assisance of ENT team.Wire guided endoscopic dilation of the PCES was done to 12 mm. In 2 mo, the stricture was dilated to 16 mm. 3) Combined approach- Laryngeal Jack technique and Retrograde Esophageal Membranotomy: In a 41 yr. female with complete dysphagia (even to saliva), PCES opening could not be identified despite the Laryngeal Jack technique under general anesthesia. After the removal of PEG tube(24 Fr), a 6-mm endoscope(EG1840, Pentax)was passed into the stomach and up into the esophagus. A complete esophageal membranous obstruction was noted. After transillumination from above through the laryngoscope, the thinnest portion of the membrane was punctured with a 5-4-3 catheter, followed by wire guided balloon dilation to 8 mm. In 3 mo, the stricture was dilated to 12-mm. Outcome: All patients gained weight & their PEG tubes were removed. Complications:nil. Conclusions: PCES can be successfully managed by endoscopic dilation without significant morbidity or mortality. Special techniques like the Laryngeal Jack assistance or the combined approach can be useful in difficult cases. Reconstructive surgery can be avoided.

Introduction: There is little data on the time spent by the patient for endoscopy. Information on the time spent for various components may help identify areas for future improvement to contain the cost of endoscopy. Aim: To prospectively study the time spent by the patient in the endoscopy unit (before, during, and after the procedure) for conscious sedation endoscopy in an academic center. Methods & Results: Data was collected on a proforma prospectively by the endoscopy unit nurses on all the pts undergoing GI endoscopy for four weeks in August & September 1999. 165 endoscopies were done on 160 pts. Data collection was complete (100%) in 121 (73%) procedures and data of this 121 pts forms the basis for this report. Demography of the endoscopy unit: a) Endoscopy Unit: Procedure rooms for endocopy: 2 (3rd room for bronchoscopy, liver biopsy, paracentesis, and bone biopsy); Preparation & recovery beds for all the procedures: 5; b) Staff: One endoscopist supervised 2 fellows in training for the day; a nurse & a technician assisted the procedure in each room; 2 nurses staffed the preparation & recovery area; 2 secretaries ran the endoscopy office. c) Endoscopy equipment: EGD: 5 (3 adult, 1 Pediatric, 1 Therapeutic); colonoscopes: 4; ERCP scopes: 2; scope cleaning units: 2. Time study: See table Conclusions: Our findings suggest that efforts should be directed towards reducing preparation & recovery time & waiting prior to the procedure. Alternatives include unsedated endoscopy & reversal of sedation.

Tatarski [V. I. Tatarski, Wave Propagation in a Turbulent Medium (McGraw‐Hill, New York, 1960)] has derived an expression for the effective scattering cross section of an acoustic wave incident on a remote volume of atomospheric turbulence. His result is subject to the single scatter approximation and the restriction that both transmitter and receiver be in the farfield of the large scale inhomogeneities within the volume. We derive an expression for the effective scattering cross section valid in both the near and farfield and extend these results to include the scatter of acoustic waves from underwater turbulence.