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Lesley A Osborn,1 Megan L Brenner,2 Samuel J Prater,1 Laura J Moore3 1Department of Emergency Medicine, The University of Texas Health Science Center, McGovern Medical School, Houston, TX, USA; 2Department of Surgery, The University of California – Riverside, Moreno Valley, CA, USA; 3Department of Surgery, The University of Texas Health Science Center, McGovern Medical School, Houston, TX, USA Abstract: Resuscitative endovascular balloon occlusion of the aorta (REBOA) has recently gained popularity as a minimally invasive alternative to open aortic cross-clamping in the management of patients with non-compressible hemorrhage arising below the diaphragm. The purpose of this review is to provide a description of the technical aspects of REBOA use along with an overview of the current animal and clinical data regarding its use. Keywords: REBOA, hemorrhagic shock, resuscitation

Abstract: Background: A 2021 report of the Aortic Occlusion for Resuscitation in Trauma and Acute Care Surgery multicenter registry described the outcomes of patients treated with Zone 3 resuscitative endovascular balloon occlusion of the aorta (REBOA zone 3). Our study builds upon that report, testing the hypothesis that REBOA zone 3 is associated with better outcomes than REBOA Zone 1 in the immediate treatment of severe, blunt pelvic injuries. Methods: We included adults who underwent aortic occlusion (AO) via REBOA zone 1 or REBOA Zone 3 in the emergency department for severe, blunt pelvic injuries [Abbreviated Injury Score ≥ 3 or pelvic packing/embolization/first 24 hours] in institutions with >10 REBOAs. Adjustment for confounders was accomplished with a Cox proportional hazards model for survival, generalized estimating equations for intensive care unit (ICU)-free days (IFD) and ventilation-free days (VFD) > 0 days, and mixed linear models for continuous outcomes (Glasgow Coma Scale [GCS], Glasgow Outcome Scale [GOS]), accounting for facility clustering. Results: Of 109 eligible patients, 66 (60.6%) underwent REBOA Zone 3 and 43 (39.4%) REBOA Zone 1. There were no differences in demographics, but compared with REBOA Zone 3, REBOA Zone 1 patients were more likely to be admitted to high volume centers and be more severely injured. These patients did not differ in systolic blood pressure (SBP), cardiopulmonary resuscitation in the prehospital/hospital settings, SBP at the start of AO, time to AO start, likelihood of achieving hemodynamic stability or requirement of a second AO. After controlling for confounders, compared with REBOA Zone 3, REBOA Zone 1 was associated with a significantly higher mortality (adjusted hazard ratio, 1.51; 95% confidence interval [CI], 1.04-2.19), but there were no differences in VFD > 0 (adjusted relative risk, 0.66; 95% CI, 0.33-1.31), IFD > 0 (adjusted relative risk, 0.78; 95% CI, 0.39-1.57), discharge GCS (adjusted difference, -1.16; 95% CI, -4.2 to 1.90) or discharge GOS (adjusted difference, -0.67; 95% CI -1.9 to 0.63). Conclusions: This study suggests that compared with REBOA Zone 1, REBOA Zone 3 provides superior survival and is not inferior regarding other adverse outcomes in patients with severe blunt pelvic injuries., (Copyright © 2023 by the Shock Society.)

Importance: Aortic occlusion (AO) is a lifesaving therapy for the treatment of severe traumatic hemorrhagic shock; however, there remains controversy whether AO should be accomplished via resuscitative thoracotomy (RT) or via endovascular balloon occlusion of the aorta (REBOA) in zone 1., Objective: To compare outcomes of AO via RT vs REBOA zone 1., Design, Setting, and Participants: This was a comparative effectiveness research study using a multicenter registry of postinjury AO from October 2013 to September 2021. AO via REBOA zone 1 (above celiac artery) was compared with RT performed in the emergency department of facilities experienced in both procedures and documented in the prospective multicenter Aortic Occlusion for Resuscitation in Trauma and Acute Care Surgery (AORTA) registry. Propensity score matching (PSM) with exact institution matching was used, in addition to subgroup multivariate analysis to control for confounders. The study setting included the ED, where AO via RT or REBOA was performed, and participants were adult trauma patients 16 years or older., Exposures: AO via REBOA zone 1 vs RT., Main Outcomes and Measures: The primary outcome was survival. Secondary outcomes were ventilation-free days (VFDs), intensive care unit (ICU)-free days, discharge Glasgow Coma Scale score, and Glasgow Outcome Score (GOS)., Results: A total of 991 patients (median [IQR] age, 32 [25-48] years; 808 male individuals [81.9%]) with a median (IQR) Injury Severity Score of 29 (18-50) were included. Of the total participants, 306 (30.9%) had AO via REBOA zone 1, and 685 (69.1%) had AO via RT. PSM selected 112 comparable patients (56 pairs). REBOA zone 1 was associated with a statistically significant lower mortality compared with RT (78.6% [44] vs 92.9% [52]; P = .03). There were no significant differences in VFD greater than 0 (REBOA, 18.5% [10] vs RT, 7.1% [4]; P = .07), ICU-free days greater than 0 (REBOA, 18.2% [10] vs RT, 7.1% [4]; P = .08), or discharge GOS of 5 or more (REBOA, 7.5% [4] vs RT, 3.6% [2]; P = .38). Multivariate analysis confirmed the survival benefit of REBOA zone 1 after adjustment for significant confounders (relative risk [RR], 1.25; 95% CI, 1.15-1.36). In all subgroup analyses (cardiopulmonary resuscitation on arrival, traumatic brain injury, chest injury, pelvic injury, blunt/penetrating mechanism, systolic blood pressure ≤60 mm Hg on AO initiation), REBOA zone 1 offered an either similar or superior survival., Conclusions and Relevance: Results of this comparative effectiveness research suggest that REBOA zone 1 provided better or similar survival than RT for patients requiring AO postinjury. These findings provide the ethically necessary equipoise between these therapeutic approaches to allow the planning of a randomized controlled trial to establish the safety and effectiveness of REBOA zone 1 for AO in trauma resuscitation.

Background: Intimate partner violence (IPV) is a significant cause of injury, and in pregnant patients (PIPV) poses a risk to both mother and fetus. Characteristics and outcomes for PIPV patients have not been well described. We hypothesize that PIPV patients have higher admission rates and mortality than non-IPV pregnant trauma (PT) patients and nonpregnant female IPV patients of childbearing age. We also hypothesize differences exist between PIPV and PT patient injury patterns, allowing for targeted IPV screening., Study Design: The Nationwide Emergency Department Sample database was queried from 2010 to 2014 to identify IPV in adult women patients by injury code E967.3. Patients were compared in 2 ways, PIPV vs PT and PIPV vs nonpregnant female IPV patients. Demographics, injury mechanisms, and National Trauma Data Standard injury diagnoses were surveyed. Primary outcomes were hospital admissions and mortality. Logistic regression was used to estimate risk factors of the outcomes of hospitalization and IPV victimization in pregnant injured patients., Results: There were 556 PIPV patients, 73,970 PT patients, and 56,543 nonpregnant female IPV patients. When comparing PIPV to PT, more PIPV patients had Medicaid coverage or were self-pay. Suffocation, head injuries, face/neck/scalp contusions, multiple contusions, and abrasions/friction burns were more prevalent in PIPV patients. Mortality and hospital admissions were scarce among all cohorts. Predictors of IPV victimization among injured pregnant patients include multiple injuries, head injuries, face/neck/scalp contusions, abrasions/friction burns, contusions of multiple sites, and those with Medicaid or self-pay coverage., Conclusions: Among injured pregnant patients, those with multiple injuries, head injuries, contusions of the face/neck/scalp, abrasions/friction burns, and multiple contusions should undergo IPV screening. Admissions and mortality are low; therefore, prevention measures should be implemented in the emergency department to reduce repeat victimization., (Copyright © 2022 by the American College of Surgeons. Published by Wolters Kluwer Health, Inc. All rights reserved.)

Background/purpose: Resuscitative endovascular balloon occlusion of the aorta (REBOA) has emerged as an alternative technique for traumatic hemorrhage control in the adult population. The purpose of this study is to describe the details of REBOA placement in adolescent trauma patients., Methods: Patients 18 years of age or less who received REBOA for aortic occlusion (AO) from August 2013 to February 2017 at 2 urban tertiary care centers were included., Results: 7 adolescent trauma patients received REBOA by trauma surgeons for both blunt (n = 4) and penetrating mechanisms (n = 3); mean age was 17 + 1.5 years, mean admission lactate 13.0 + 4.85 mmol/L, and mean Hgb 10.7 + 2.7 g/dL. 3 patients received REBOA through a 12Fr sheath and 4 through a 7Fr sheath. AO occurred mostly at the distal thoracic aorta (Zone I) (85.7%) and also in the distal abdominal aorta (Zone III) (14.3%). 57% of patients were in arrest with ongoing CPR at the time of REBOA. In-hospital mortality was 57%; all of these patients were in arrest at the time of REBOA, had return of spontaneous circulation (ROSC), and survived to the operating room. No complications from REBOA were identified., Conclusion: REBOA appears to be feasible for use in adolescents despite their smaller caliber vessels, even with use of a 12Fr sheath. REBOA results in improved physiology and can bridge adolescent trauma patients presenting in extremis to the operating room., Type of Study: Treatment/therapeutic study LEVEL OF EVIDENCE: Level IV., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Purpose: Aortic occlusion (AO) increases proximal perfusion and may improve rates of return of spontaneous circulation (ROSC). The objective of this study was to investigate the hemodynamic effects of cardiopulmonary resuscitation (CPR) and AO by REBOA on patients in traumatic cardiac arrest., Methods: Patients admitted between February 2013 and May 2017 at a tertiary center who suffered traumatic arrest, had an arterial line placed during resuscitation, and received CPR and REBOA which were included. In-hospital CPR data were obtained from videography. Arterial waveforms were recorded at 240 Hz., Results: 11 consecutive patients were included, 82% male; mean (± SD) age 37 ± 19 years. 55% suffered blunt trauma and the remaining penetrating injuries. 64% arrested out of hospital. During compressions with AO, the mean systolic blood pressure (SBP) was 70 ± 22 mmHg, mean arterial pressure (MAP) 43 ± 19 mmHg, and diastolic blood pressure (DBP) 26 ± 17 mmHg. Nine (82%) had ROSC, with eight having multiple periods of ROSC and arrest in the initial period. In-hospital mortality was 82%. Cardiac ultrasonography was used during arrest in 73%. In two patients with arterial line data before and after AO, SBP (mmHg) improved from 51 to 73 and 55 to 96 during arrest after AO., Conclusions: High-quality chest compressions coupled with aortic occlusion may generate adequate perfusion pressures to increase the rate of ROSC. New technology capable of transducing central arterial pressure may help us to understand the effectiveness of CPR with and without aortic occlusion. REBOA may be a useful adjunct to high-quality chest compressions during arrest.

Resuscitative endovascular balloon occlusion of the aorta (REBOA) is a temporizing maneuver for noncompressible torso hemorrhage. To our knowledge, this single-center brief report provides the most extensive anesthetic data published to date on patients who received REBOA. As anticipated, patients were critically ill, exhibiting lactic acidosis, hypotension, hyperglycemia, hypothermia, and coagulopathy. All patients received blood products during their index operations and received less inhaled anesthetic gas than normally required for healthy patients of the same age. This study serves as an important starting point for clinician education and research into anesthetic management of patients undergoing REBOA.

Objectives: The aim of this study was to evaluate the effect of a recently active endovascular trauma service (ETS) on case volume and time to hemostasis, as a complement to an existing interventional radiology (IR) service., Summary Background Data: Endovascular techniques are vital for trauma care, but timely access can be a challenge. There is a paucity of data on the effect of a multispecialty team for delivery of endovascular hemorrhage control., Methods: The electronic medical record of trauma patients undergoing endovascular procedures between 2013 and 2018 was queried for provider type (IR or ETS). Case volume and rates were expressed per 100 monthly admissions, normalizing for seasonal variation. Interrupted time series analysis was used to model the case rate pre- and post-introduction of the ETS. Admission-to-procedure-time data were collected for pelvic angioembolization as a marker of patients requiring emergency hemostasis., Results: During 6 years, 1274 admission episodes required endovascular interventions. Overall case volume increased from 2.7 to 3.6 at a rate of 0.006 (P = 0.734) after introduction of the ETS. IR case volume decreased from 3.3 to 2.6 at a rate of 0.03 (P = 0.063). ETS case volume increased at a rate of 0.048 (P < 0.001), which was significantly different from the IR trend (P < 0.001). Median (interquartile range) time-to-procedure (hours) was significantly shorter for pelvic angioembolization [3.0 (4.4) vs 4.3 (3.6); P < 0.001] when ETS was compared to IR., Conclusion: A surgical ETS increases case volume and decreases time to hemostasis for trauma patients requiring time sensitive interventions. Further work is required to assess patient outcome following this change.

Background: The objective of this study was to investigate the hemodynamic effects of aortic occlusion (AO) during Resuscitative Endovascular Balloon Occlusion of the Aorta (REBOA) using a sophisticated continuous vital sign (CVS) monitoring tool., Methods: Patients admitted between February 2013 and May 2017 at a tertiary center that received REBOA were included. Patients in cardiac arrest before or at the time of REBOA were excluded. Time of AO was documented by time-stamped videography and correlated with CVS data., Results: 28 patients were included, mean (standard deviation) ISS was 38 (11). 18 received Zone 1 (distal thoracic aorta) and 10 received Zone 3 (distal abdominal aorta) AO. Among Zone 1 patients the pre-AO systolic blood pressure (SBP) nadir was 64 (19) mmHg, which increased to a mean of 124 (29) mmHg within 5 min after AO (p < 0.01). Among Zone 3 patients the pre-AO SBP nadir was 75 (19) mmHg, which increased to a mean of 98 (14) mmHg within 5 min after AO (p < 0.01). 72% of Zone 1 patients had episodes during AO where SBP was less than 90 mmHg as compared to 80% of Zone 3 patients (p = 0.51). 100% of Zone 1 patients had periods during AO where SBP was greater than 140 mmHg as compared to 70% Zone 3 patients (p = 0.04). The overall mean decrease in SBP after balloon deflation was 13 (20) mmHg (p < 0.01), with similar decreases among groups (14 (21) mmHg vs 12 (18) mmHg for Zone 1 and 3 patients, respectively (p = 0.85)). Patients undergoing Zone 1 AO were more likely to have an acute change (increase or decrease) in their heart rate immediately after AO as compared to Zone 3 AO (p = 0.048)., Conclusions: Significant hemodynamic alterations occur before, during, and after AO. The effects of Zone 1 AO on blood pressure and heart rate appear different than Zone 3 AO. This may have important implications for cardiac or cerebral function and perfusion goals, particularly with concomitant injuries such as cardiac contusion or traumatic brain injury., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Background: Resuscitative endovascular balloon occlusion of the aorta (REBOA) is a torso hemorrhage control adjunct. Aortic branch vessel flow (BVF) during REBOA is poorly characterized and has implications for ischemia-reperfusion injury. The aim of this study is to quantify BVF in hypovolemic shock with and without REBOA., Methods: Female swine (79-90 kg) underwent anesthesia, 40% controlled hemorrhage and sonographic flow monitoring of the carotid, hepatic, superior mesenteric, renal, and femoral arteries. Animals were randomized to REBOA (n = 5) or no-REBOA (n = 5) for 4 hours, followed by full resuscitation and balloon deflation for 1 hour., Results: All animals were successfully induced into hemorrhagic shock with a mean decrease of flow in all vessels of 50% from baseline (p < 0.001). Deployment of REBOA resulted in a 200% to 400% increase in carotid flow, but near complete abolition of BVF distal to the balloon. The no-REBOA group saw recovery of BVF to 100% of baseline in all measured vessels, except the hepatic at 50% to 75%. two-way analysis of variance confirmed a significant difference between the groups throughout the protocol (p < 0.001). During resuscitation, the REBOA group saw BVF restore to between 25% and 50%, but never achieving baseline values. The lactate at 4 hours was significantly higher in the REBOA versus no-REBOA group (17.2 ± 0.1 vs. 4.9 ± 1.4; p < 0.001)., Conclusion: REBOA not only abolishing BVF during occlusion, but appears to have a post-REBOA effect, reducing visceral perfusion. This may be a source of REBOA associated ischemia-reperfusion injury and warrants further investigation in order to mitigate this effect.

The Stop the Bleed initiative empowers and trains citizens as immediate responders, to recognize and control severe hemorrhage. We sought to determine the retention of short-term knowledge and ability to apply a Combat Application Tourniquet (CAT) in 10 nonmedical personnel. A standard "Stop the Bleed" (Bleeding Control) course was taught including CAT application. Posttraining performance was assessed at 30 days using a standardized mannequin with a traumatic below-knee amputation. Technique, time, pitfalls, and feedback were all recorded. No participant had placed a CAT before the initial class. After the initial class, self-report by a Likert scale survey revealed an increased confidence in tourniquet application from 2.4 pretraining to 4.7 posttraining. At 30 days, confidence decreased to 3.4 before testing. Six of 10 were successful at tourniquet placement. Completion time was 77.75 seconds (43-157 seconds). Successful participants reported a confidence level of 4.7 versus those unsuccessful at 3.3. The "Stop the Bleed" initiative teaches lifesaving skills to the public through a short training course. This information regarding the training of nonmedical personnel may assist in strengthening training efforts for the public. Further investigations are needed to characterize skill degradation and retention over time.

Resuscitative endovascular balloon occlusion of the aorta (REBOA) is a temporizing maneuver used to decrease hemorrhage, and thus perfusion, below the level of aortic occlusion (AO). We sought to investigate lower extremity ischemia in patients who received REBOA. Between February 2013 and September 2016 patients at a tertiary center that received REBOA and survived more than six hours were enrolled. Thirty-one patients were identified, the mean ISS was 40 ± 14 and inhospital mortality was 39 per cent. Twenty received REBOA in zone 1 (distal thoracic aorta). Three (15%) developed lower extremity compartment syndrome (LECS) after zone 1 REBOA. Injury of iliofemoral arteries and veins was each associated with calf fasciotomies (both P = 0.005). A longer duration of AO at zone 1 was associated with calf and thigh fasciotomy (P = 0.046 and P = 0.048, respectively). Iliofemoral arterial injury was associated with thigh fasciotomy (P = 0.04). Eleven patients received REBOA in zone 3 (distal abdominal aorta). Five (45%) patients underwent fasciotomy; four (36%) due to LECS. Femoral arterial injury was associated with calf fasciotomies (P = 0.02). There was no association with sheath size or laterality and need for fasciotomy. Neither groin access for REBOA or AO solely caused limb loss or LECS. The contribution to distal ischemia by REBOA remains unclear in patients with lower extremity injury.

Background: Resuscitative endovascular balloon occlusion of the aorta (REBOA) is used to decrease hemorrhage below the level of aortic occlusion (AO); however, the amount of collateral blood flow below the level of occlusion is unknown. Our aim was to investigate blood flow patterns during complete AO in patients who underwent CT scan after REBOA., Study Design: Between February 2013 and January 2017, patients who received REBOA and underwent CT scan with intravenous contrast during full AO were included. Patients were excluded if they had a CT scan performed with the balloon partially or fully deflated., Results: Nine patients (8 men) were included; all had blunt trauma. Mean Injury Severity Score (±SD) was 48 ± 8 and mean age was 45 ± 19 years. Four had supra-celiac AO, and 5 had infra-renal AO. Arterial contrast enhancement was noted below the level of AO in all patients, and distal to REBOA sheath placement in 5. Collateralization from arteries above and below the AO was identified in all patients. Contrast extravasation distal to AO was identified in 4 patients, and hematomas in 8. Distal vascular enhancement patterns varied by level of AO and contrast administration site., Conclusions: Aortic occlusion appears to dramatically decrease, but does not completely impede, distal perfusion during REBOA due to multiple pathways of collateralization. Active extravasation and hematomas can still be detected in the setting of full AO, with purposefully timed contrast and image acquisition. Blood flow persists below the level of both the AO and in-dwelling sheath. Dynamic flow studies are needed to determine the contribution of AO and sheath placement to distal tissue ischemia., (Copyright © 2017 American College of Surgeons. All rights reserved.)

Background: Resuscitative endovascular balloon occlusion of the aorta (REBOA) is a torso hemorrhage control technique. To expedite deployment, inflation is frequently performed as a blind technique with minimal imaging, which carries a theoretical risk of aortic injury. The objective of this study was to examine the relationship between balloon inflation, deformation and the risk of aortic rupture., Methods: Compliant balloon catheters were incrementally inflated in segments of cadaveric swine aorta. Serial longitudinal and circumferential measurements were recorded, along with the incidence of aortic rupture., Results: Fourteen cadaveric swine aorta segments were tested with mean (±SD) baseline aortic diameter (mm) of 14.2±3.4. Rupture occurred in three aortas. The mean baseline diameters (mm) of the aortic segments that were ruptured were significantly smaller than those that did not rupture (8.9±1.2 vs 15.6±1.9; P<0.001). The maximal circumferential stretch ratios were significantly higher in the aorta segments that ruptured compared with those that did not (1.9±0.1 vs 1.5±0.1; P<0.001). The maximal amount of balloon longitudinal deformation was 80 mm (116% longer than the intended working length)., Conclusions: Inflation of aortic balloon catheters carries an inherent risk of aortic injury, which may be minimized through an understanding of the intrinsic characteristics of the aorta and compliant balloons. Smaller diameter aortic segments undergoing overinflation, particularly beyond a circumferential stretch ratio of 1.8, are at risk of aortic rupture., Level of Evidence: Level II., Competing Interests: Competing interests: JJM and MLB are clinical advisory board members for Prytime Medical Inc.

Despite technological advancements, REBOA is associated with significant risks due to complications of vascular access and ischemia-reperfusion. The inherent morbidity and mortality of REBOA is often compounded by coexisting injury and hemorrhagic shock. Additionally, the potential for REBOA-related injuries is exaggerated due to the growing number of interventions being performed by providers who have limited experience in endovascular techniques, inadequate resources, minimal training in the technique, and who are performing this maneuver in emergency situations. In an effort to ultimately improve outcomes with REBOA, we sought to compile a list of complications that may be encountered during REBOA usage. To address the current knowledge gap, we assembled a list of anecdotal complications from high-volume REBOA users internationally. More importantly, through a consensus model, we identify contributory factors that may lead to complications and deliberate on how to recognize, mitigate, and manage such events. An understanding of the pitfalls of REBOA and strategies to mitigate their occurrence is of vital importance to optimize patient outcomes.

The medical advancements made during the wars in Iraq and Afghanistan have resulted in an unprecedented survival rate, yet there is still a significant number of deaths that were potentially survivable. Additionally, the ability to deliver casualties to definitive surgical care within the "golden hour" is diminishing in many areas of conflict. Resuscitative endovascular balloon occlusion of the aorta (REBOA) has been implemented successfully in the hospital setting. REBOA may be a possible adjunct for the Role I and point-of-injury (POI) care to provide temporary control of noncompressible torso hemorrhage (NCTH) and junctional hemorrhage. Here the authors advocate for the development of the Role I Resuscitation Team (RT) and a training pathway to meet the challenge of the changing battlefield., (2017.)

Background: Resuscitative endovascular balloon occlusion of the aorta (REBOA), used to temporize noncompressible and junctional hemorrhage, may be deployable to the forward environment. Our hypothesis was that nonsurgeon physicians and high-level military medical technicians would be able to learn the theory and insertion of REBOA., Methods: US Army Special Operations Command medical personnel without prior endovascular experience were included. All participants received didactic instruction of the Basic Endovascular Skills for Trauma Course™ together, with individual evaluation of technical skills. A pretest and a posttest were administered to assess comprehension., Results: Four members of US Army Special Operations Command-two nonsurgeon physicians, one physician assistant, and one Special Operations Combat Medic-were included. REBOA procedural times moving from trial 1 to trial 6 decreased significantly from 186 ± 18.7 seconds to 83 ± 10.3 seconds (ρ < .0001). All participants demonstrated safe REBOA insertion and verbalized the indications for REBOA insertion and removal through all trials. All five procedural tasks were performed correctly by each participant. Comprehension and knowledge between the pretest and posttest improved significantly from 67.6 ± 7.3% to 81.3 ± 8.1% (ρ = .039)., Conclusion: This study demonstrates that nonsurgeon and nonphysician providers can learn the steps required for REBOA after arterial access is established. Although insertion is relatively straightforward, the inability to gain arterial access percutaneously is prohibitive in providers without a surgical skillset and should be the focus of further training., (2017.)

Introduction: Major pelvic disruption with hemorrhage has a high rate of lethality. Angiographic embolization remains the mainstay of treatment. Delays to angiography have been shown to worsen outcomes in part because time spent awaiting mobilization of resources needed to perform angiography allows ongoing hemorrhage. Alternative techniques like pelvic preperitoneal packing and aortic balloon occlusion now exist. We hypothesized that time to angiographic embolization at our Level 1 trauma center would be longer than 90 minutes., Methods: A retrospective review was performed of patients with pelvic fracture who underwent pelvic angiography at our trauma center over a 10-year period. The trauma registry was queried for age, sex, injury severity score, hemodynamic instability (HI) on presentation, and transfusion requirements within 24 hours. Charts were reviewed for time to angiography, embolization, and mortality., Results: A total of 4712 patients were admitted with pelvic fractures during the study period, 344 (7.3%) underwent pelvic angiography. Median injury severity score was 29. Median 24-hour transfusion requirements were five units of red blood cells and six units of fresh frozen plasma. One hundred fifty-one patients (43.9%) presented with HI and 104 (30%) received massive transfusion (MT). Median time to angiography was 286 minutes (interquartile range, 210-378). Times were significantly shorter when stratified for HI (HI, 264 vs stable 309 minutes; p = 0.003), and MT (MT, 230 vs non-MT, 317 minutes; p < 0.001), but still took nearly 4 hours. Overall mortality was 18%. Hemorrhage (35.5%) and sepsis/multiple-organ failure (43.5%) accounted for most deaths., Conclusion: Pelvic fracture hemorrhage remains a management challenge. In this series, the median time to embolization was more than 5 hours. Nearly 80% of deaths could be attributed to early uncontrolled hemorrhage and linked to delays in hemostasis. Earlier intervention by Acute Care Surgeons with techniques like preperitoneal packing, aortic balloon occlusion, and use of hybrid operative suites may improve outcomes., Level of Evidence: Therapeutic study, level V.

Introduction: Large arterial sheaths currently used for resuscitative endovascular balloon occlusion of the aorta (REBOA) may be associated with severe complications. Smaller diameter catheters compatible with 7Fr sheaths may improve the safety profile., Methods: A retrospective review of patients receiving REBOA through a 7Fr sheath for refractory traumatic hemorrhagic shock was performed from January 2014 to June 2015 at five tertiary-care hospitals in Japan. Demographics were collected including method of arterial access; outcomes included mortality and REBOA-related access complications., Results: Thirty-three patients underwent REBOA at Zone 1 (level of the diaphragm). Most patients were male (70%), with a mean age (+SD) 50 ± 18 years, mean BMI 23 ± 4, and a median [IQR] ISS of 38 [34, 52]. Ninety-four percent of patients presented after sustaining injuries from blunt mechanisms. Twenty-four percent underwent CPR before arrival, and an additional 15% received CPR after admission. Percutaneous arterial access without ultrasound or fluoroscopy was achieved in all patients. Systolic blood pressure increased significantly following balloon occlusion (mean 62 ± 36 to 106 ± 40 mm Hg, p < 0.001). Median total duration of complete initial occlusion was 26 [range 10-35] minutes. Sixteen patients (49%) survived beyond 24 hours, and 14 patients (42%) survived beyond 30 days. Twenty-four-hour and 30-day survival were 48% and 42%, respectively. Of the patients surviving 24 hours (n = 16), median duration of sheath placement was 28 [range 18-45] hours with all removed using manual pressure to achieve hemostasis. Of 33 REBOAs, 20 were performed by Emergency Medicine practitioners, 10 by Emergency Medicine practitioners with endovascular training, and 3 by Interventional Radiologists. No complication related to sheath insertion or removal was identified during the follow-up period, including dissection, pseudoaneurysm, retroperitoneal hematoma, leg ischemia, or distal embolism., Conclusions: 7Fr REBOA catheters can significantly elevate systolic blood pressure with no access-related complications. Our results suggest that a 7Fr introducer device for REBOA may be a safe and effective alternative to large-bore sheaths, and may remain in place during the post-procedure resuscitative phase without sequelae., Level of Evidence: Therapeutic/care management, level V.

Background: Open chest cardiac massage (OCCM) is a commonly performed procedure after traumatic cardiac arrest (TCA). OCCM has been reported to be superior to closed chest compressions (CCC) in animal models and in non-TCA. The purpose of this study is to prospectively compare OCCM versus CCC in TCA using end-tidal carbon dioxide (ETCO2), the criterion standard for determining the effectiveness of chest compressions and detection of return of spontaneous circulation (ROSC), as the surrogate for cardiac output and marker for adequacy of resuscitation., Methods: This prospective observational study enrolled patients over a 9-month period directly presenting to a level 1 trauma center after TCA. Continuous high-resolution ETCO2 measurements were collected every 6 seconds for periods of CCC and OCCM, respectively. Patients receiving CCC only were compared with patients receiving CCC followed by OCCM. Student's t tests were used to compare ETCO2 within and between groups., Results: Thirty-three patients were enrolled (16 OCCM, 17 CCC-only). Mean time of CCC before OCCM was 66 seconds. Within the OCCM group, final, peak, mean, and median ETCO2 levels significantly increased when comparing the initial CCC period to the OCCM interval. Using a time-matched comparison, significant increases were observed in the final and peak but not mean and median values when comparing the first minute of CCC to the remaining time in the CCC-only group. However, when periods of OCCM were compared with equivalent periods of CCC-only, there were no differences in the initial, final, peak, mean, or median ETCO2 values. Correspondingly, no difference in rates of ROSC was observed between groups (OCCM 23.5% vs. CCC 38.9%; p = 0.53)., Conclusion: Although we could not control for confounders, we found no significant improvement in ETCO2 or ROSC with OCCM. With newer endovascular techniques for aortic occlusion, thoracotomy solely for performing OCCM provides no benefit over CCC., Level of Evidence: Therapeutic study, level III.

Introduction: Resuscitative endovascular balloon occlusion of the aorta (REBOA) is a technique that has been shown to provide central vascular control to support proximal aortic pressure and minimize hemorrhage in a wide variety of clinic settings, however the role of REBOA for emergency general surgery is less defined., Case Description: This is a report of a 44 year old man who experienced hemorrhagic shock during video-assisted retroperitoneal debridement (VARD) for necrotizing pancreatitis where REBOA was used to prevent ongoing hemorrhage and death., Discussion: This is the first documented report REBOA being used during pancreatic debridement in the literature and one of the first times it has been used in emergency general surgery. The use of REBOA is an option for those in hemorrhagic shock whom conventional aortic cross-clamping or supra-celiac aortic exposure is either not possible or exceedingly dangerous., Conclusion: REBOA allows for adequate resuscitation and can be used as a bridge to definitive therapy in a range of surgical subspecialties with minimal morbidity and complications. The risks associated with insertion of wires, sheaths, and catheters into the arterial system, as well as the risk of visceral and spinal cord ischemia due to aortic occlusion mandate that the use of this technique be utilized in only appropriate clinical scenarios., (Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Background: Blunt abdominal aortic injury (BAAI) is a rare injury. The objective of the current study was to examine the presentation and management of BAAI at a multi-institutional level., Methods: The Western Trauma Association Multi-Center Trials conducted a study of BAAI from 1996 to 2011. Data collected included demographics, injury mechanism, associated injuries, interventions, and complications., Results: Of 392,315 blunt trauma patients, 113 (0.03%) presented with BAAI at 12 major trauma centers (67% male; median age, 38 years; range, 6-88; median Injury Severity Score [ISS], 34; range, 16-75). The leading cause of injury was motor vehicle collisions (60%). Hypotension was documented in 47% of the cases. The most commonly associated injuries were spine fractures (44%) and pneumothorax/hemothorax (42%). Solid organ, small bowel, and large bowel injuries occurred in 38%, 35%, and 28% respectively. BAAI presented as free aortic rupture (32%), pseudoaneurysm (16%), and injuries without aortic external contour abnormality on computed tomography such as large intimal flaps (34%) or intimal tears (18%). Open and endovascular repairs were undertaken as first-choice therapy in 43% and 15% of cases, respectively. Choice of management varied by type of BAAI: 89% of intimal tears were managed nonoperatively, and 96% of aortic ruptures were treated with open repair. Overall mortality was 39%, the majority (68%) occurring in the first 24 hours because of hemorrhage or cardiac arrest. The highest mortality was associated with Zone II aortic ruptures (92%). Follow-up was documented in 38% of live discharges., Conclusion: This is the largest BAAI series reported to date. BAAI presents as a spectrum of injury ranging from minimal aortic injury to aortic rupture. Nonoperative management is successful in uncomplicated cases without external aortic contour abnormality on computed tomography. Highest mortality occurred in free aortic ruptures, suggesting that alternative measures of early noncompressible torso hemorrhage control are warranted., Level of Evidence: Epidemiologic study, level III; therapeutic study, level IV.

Penetrating injuries to the aorta usually result in immediate life-threatening hemorrhage. Because these lesions are typically either fatal or identified and controlled surgically, chronic pseudoaneurysms after penetrating aortic trauma are rare. Most of these patients present with rupture or local complications, and management before the endovascular era has historically been open repair. As such, there are limited data to guide the modern management of an asymptomatic, posttraumatic aortic pseudoaneurysm. Here, we describe a 54-year-old man who was diagnosed with an incidental, supraceliac aortic pseudoaneurysm 14 years after an abdominal stab wound. He underwent successful and uncomplicated endovascular repair., (Copyright © 2014 Elsevier Inc. All rights reserved.)

Objective: Blunt iliac arterial injuries (BIAI) require complex management but are rare and poorly studied. We investigated the presentation, management, and outcomes of patients with blunt common or external iliac arterial injuries., Methods: We identified and reviewed 112 patients with BIAI admitted between 2000 and 2011 at a Level I trauma center. Patients with common/external iliac artery injuries (CE group) were primarily analyzed, with patients with injuries of the internal iliac artery or its major branches (IB group) included for comparison of pelvic arterial trauma., Results: Twenty-four patients had CE and 88 had IB injuries. Mean ages (45 ± 19 years) and gender (86% male) were similar between groups. The mean injury severity score was 40 ± 14 (CE, 36 ± 15; IB, 40 ± 14; P = .19), indicating severe trauma. Twenty (83%) of the CE patients presented with signs of leg malperfusion. Admission factors associated with CE injury were crush mechanism of injury (37% vs 17%; P = .03) and pelvic soft tissue trauma (50% vs 15%; P < .01). The CE group had higher early mortality rates, both within 3 hours of admission (50% vs 19%; P = .04) and prior to iliac intervention (42% vs 3%; P < .01). Among those surviving to management, CE patients were more likely to undergo open repair or revascularization (68% vs 3%; P < .01) and had a higher rate of leg amputation (50% vs 6%; P < .01), with 8/12 (67%) culminating in hemipelvectomy. Risk factors for amputation included leg malperfusion, high-grade pelvic fractures, pelvic soft tissue trauma, and increasing leg injury severity. Overall mortality was 40%, and was similar between the injury groups. Among CE patients, need for amputation, pelvic fractures, and wounds were associated with inpatient mortality., Conclusions: This is the largest series to date of blunt CE injuries and demonstrates distinct clinical features and outcomes for these patients. They have high risk for early death and proximal leg amputation. CE injury is specifically associated with serious open pelvic soft tissue injury, which, along with high-grade pelvic fractures, is a risk factor for amputation and death. On-demand emergent endovascular intervention may play an important role in improving management of these complex injuries., (Copyright © 2014 Society for Vascular Surgery. Published by Mosby, Inc. All rights reserved.)

Background: Blunt abdominal aortic injury (BAAI) is historically associated with significant morbidity and mortality. Our institutional experience was analyzed to define current patterns of injury and to help guide management., Methods: Adult patients with BAAI between January 2000 and July 2011 were identified from our trauma registry. Medical, radiographic, and autopsy records were reviewed for relevant clinical data. Management and outcomes were compared between patients with minimal aortic injury limited to the intima (MAI) compared to more significant aortic injury (SAI)., Results: Nine patients had MAI and 8 had SAI, including 2 dissections, 2 pseudoaneurysms, 2 branch avulsions, 1 thrombosis, and 1 transection. The MAI and SAI groups had similar demographics and patterns of injury, and all patients had significant polytrauma, with a mean injury severity score of 42. More MAI than SAI patients were managed nonoperatively (100% vs. 38%; P=0.01). All observed patients underwent repeat imaging during the index admission, 85% within 72 hours, and no observed lesions led to malperfusion, death, or progression during the index admission. One MAI progressed to a pseudoaneurysm within 8 months. Five SAI patients underwent aortic-related repairs, including 2 endovascular stent grafts, 2 open primary repairs, and 1 axillobifemoral bypass. Overall, 15 (88%) patients underwent procedures for any injury-9 required laparotomy (53%) and 2 underwent thoracotomy. There were 6 (35%) deaths, 2 attributable to aortic injury-1 from hemorrhage and 1 from hyperkalemic cardiac arrest after prolonged ischemia from infrarenal aortic occlusion. Among patients who survived the initial resuscitation, SAI was associated with a significantly higher mortality rate compared to MAI (50% vs. 0%; P=0.03)., Conclusions: Patients with MAI are at low risk of complications and may be considered for observation. Patients with SAI requiring intervention manifest clinically and/or radiographically at presentation. Those not associated with bleeding, malperfusion, or thromboembolism may be observed with interval imaging. For all observed patients, long-term surveillance is required to document complete resolution or stability, because even MAI can progress to a more complex lesion., (Copyright © 2013 Elsevier Inc. All rights reserved.)

Background: A requirement for improved methods of hemorrhage control and resuscitation along with the translation of endovascular specialty skills has resulted in reappraisal of resuscitative endovascular balloon occlusion of the aorta (REBOA) for end-stage shock. The objective of this report was to describe implementation of REBOA in civilian trauma centers., Methods: Descriptive case series of REBOA (December 2012 to March 2013) used in scenarios of end-stage hemorrhagic shock at the University of Maryland, R. Adams Cowley Shock Trauma Center, Baltimore, Maryland, and Herman Memorial Hospital, The Texas Trauma Institute, Houston, Texas., Results: REBOA was performed by trauma and acute care surgeons for blunt (n = 4) and penetrating (n = 2) mechanisms. Three cases were REBOA in the descending thoracic aorta (Zone I) and three in the infrarenal aorta (Zone III). Mean (SD) systolic blood pressure at the time of REBOA was 59 (27) mm Hg, and mean (SD) base deficit was 13 (5). Arterial access was accomplished using both direct cutdown (n = 3) and percutaneous (n = 3) access to the common femoral artery. REBOA resulted in a mean (SD) increase in blood pressure of 55 (20) mm Hg, and the mean (SD) aortic occlusion time was 18 (34) minutes. There were no REBOA-related complications, and there was no hemorrhage-related mortality., Conclusion: REBOA is a feasible and effective means of proactive aortic control for patients in end-stage shock from blunt and penetrating mechanisms. With available technology, this method of resuscitation can be performed by trauma and acute care surgeons who have benefited from instruction on a limited endovascular skill set. Future work should be aimed at devices that allow easy, fluoroscopy-free access and studies to define patients most likely to benefit from this procedure., Level of Evidence: Therapeutic study, level V.

Purpose: To define the beneficial and detrimental effects of adding exercise to direct magnetic resonance (MR) shoulder arthrography., Materials and Methods: Direct, intraarticular, gadolinium arthrography of the shoulder was performed in 41 patients, who underwent 1.5-T MR imaging before and after 1 minute of arm swinging. Fourteen milliliters of dilute gadolinium solution was injected. Two readers blinded to exercise independently graded the randomly distributed images with a five-point scale for capsular contrast material resorption; extraarticular contrast material leakage; rotator cuff, glenoid labrum, and anterior capsule conspicuity; and partial-thickness or full-thickness rotator cuff tear and labral tear detectability. The sign test was performed to evaluate the significance of differences between preexercise and postexercise grading for each reader. A second review was performed, with direct side-by-side comparison of preexercise and postexercise images., Results: There was evidence of increased capsular resorption after exercise but no alteration in the depiction of the rotator cuff tendons or glenoid labrum. There was no significant extraarticular contrast material leakage after exercise and no alteration in depiction of the anterior capsule. There was no difference in the detectability of rotator cuff or labral tears., Conclusion: Exercise with direct shoulder MR arthrography has no beneficial or detrimental effect on image quality or on the depiction of rotator cuff or labral tears.

Three new C20-gibberellins, GA97 (2 beta-hydroxy-GA53), GA98 (2 beta-hydroxy-GA44) and GA99 (2 beta-hydroxy-GA19), have all been isolated from spinach, GA97 also from tomato root cultures and pea pods, and GA98 from maize pollen. The structures of these compounds were established by GC-mass spectrometric comparisons of the trimethylsilylated methyl esters with authentic samples prepared from gibberellic acid (GA3).

Sucrose synthase is proposed to play an important role in the early stages of tomato fruit (Lycopersicon esculentum Mill.) growth. In this work, the temporal and spatial expression patterns of sucrose synthase during tomato fruit development were investigated. Fruit contained the majority of the sucrose synthase protein and mRNA relative to other organs. Only trace levels of sucrose synthase protein and mRNA were detected in the stem, petiole, and roots. Sucrose synthase mRNA was detected in pistils prior to anthesis, reached peak levels in fruit 5 to 7 d after anthesis (DAA), and was not detectable after 35 DAA. Sucrose synthase protein levels reached a maximum at 20 to 25 DAA and then declined to nondetectable levels after 45 DAA. The lack of coordination between protein and mRNA levels suggests that sucrose synthase expression may be controlled at the levels of both transcription and translation. Sucrose synthase mRNA was differentially localized in the fruit, being most abundant in the mesocarp cells adjacent to the placenta, the columella, and the cells surrounding the vascular bundle. Except around the vascular tissue, the localization of sucrose synthase mRNA positively correlates with starch granule accumulation at the cellular level.

Contrasting evidence has accumulated regarding the role of acid invertase and sucrose synthase in tomato fruit sink establishment and maintenance. In this work the relationships among the activities of sucrose synthase and acid invertase, Lycopersicon esculentum Mill cv UC-82B fruit growth, and starch accumulation were analyzed in fruit at 0 to 39 d after anthesis. Sucrose synthase, but not acid invertase, was found to be positively correlated with tomato fruit relative growth rate and with starch content in the pericarp tissue. A similar association between sucrose synthase activity and starch accumulation was also evident in the basal portion of the stem. Heat-shock treatments, which inhibited the increase in sucrose synthase activity at the beginning of the light period and had no effect on acid invertase activity, were used to examine the importance of sucrose synthase in relation to sucrose metabolism and starch synthesis. After the heat-shock treatment, concomitantly with the suppressed sucrose synthase activity relative to the controls, there was a reduction in sucrose cleavage and starch accumulation. These data substantiate the conclusion that, during the early phases of tomato fruit development, sucrose synthase rather than acid invertase is the dominant enzyme in metabolizing imported sucrose, which in turn plays a part in regulating the import of sucrose into the fruit.

Estimation of abscisic acid (ABA) content in potato (Solanum commersonii) suspension-cultured cells with an enzyme-immunoassay (EIA) was investigated. In crude extracts of potato cultured cells or even after simple clean-up using C18 cartridge, EIA based on commercial monoclonal antibodies (Idetek, Inc) failed to detect any ABA content. An interference could be removed by partitioning against ethyl acetate after the C18 cartridge so that the EIA yielded an estimate of ABA similar to that determined by high pressure liquid chromatography and gas chromatography-mass spectrometry analysis. These results demonstrate the presence of metabolites in potato cultured cell extract that prevent the binding of ABA to its binding site but not the binding of tracer.

Exogenous applications of gibberellins (GAs) increased the extractable activity of leaf sucrose phosphate synthase (SPS) in soybean (Glycine max [L.]) and spinach (Spinacia oleracea [L.]). The response to GA applications was detectable within 2 h postapplication and was still observed 6 h, 24 h, and 7 d after treatment. When paclobutrazol, a GA biosynthesis inhibitor, was applied to intact soybean and spinach plants, decreased extractable SPS activity resulted within 24 h following the treatment. Different methods of GA application (spray, injection, capillary wick, and excised leaf systems) produced similar effects on SPS activity of soybean leaves. Protein synthesis in soybean leaves appeared to be necessary for GA-promoted SPS activity because gibberellic acid only partially reversed the inhibitory effect of pretreatment with cycloheximide. Levels of SPS protein from crude extracts of spinach plants were measured by a dot blot technique using monoclonal antibodies against SPS. Application of gibberellic acid to spinach leaves increased levels of SPS protein 2 h, 24 h, and 7 d after treatment. The results suggest that, in both soybean and spinach, GA is one of the endogenous hormonal factors that regulate the steady-state level of SPS protein and, hence, its activity.

An important part in the understanding of the regulation of carbon partitioning within the leaf is to investigate the endogenous variations of parameters related to carbon metabolism. This study of diurnal changes in the activities of sucrose-synthesizing enzymes and levels of nonstructural carbohydrates in intact leaves of field-grown soybean plants (Glycine max [L.]) showed pronounced diurnal fluctuations in sucrose phosphate synthase (SPS) activity. However, there was no distinct diurnal change in the activity of fructose-1,6-bisphosphatase (F1,6BPase). SPS activity in leaves from plants grown in controlled environments presented two peaks during the light period. In contrast to field-grown plants, F1,6BPase activity in leaves from growth chamber-grown plants manifested one peak during the first half of the light period. In plants grown under both conditions, sucrose and starch accumulation rates were highest during early hours of the light period. By the end of the dark period, most of the starch was depleted. A pattern of diurnal fluctuations of abscisic acid (ABA) levels in leaves was also observed under all growing conditions. Either imposition of water stress or exogenous applications of ABA inhibited F1,6BPase activity. However, SPS-extractable activity increased following water deficit but did not change in response to ABA treatment. Gibberellin application to intact soybean leaves increased levels of both starch and sucrose. Both gibberellic acid (10(-6)m) and gibberellins 4 and 7 (10(-5)m) increased the activity of SPS but had an inconsistent effect on F1,6BPase. Correlation studies between the activities of SPS and F1,6BPase suggest that these two enzymes are coordinated in their function, but the factors that regulate them may be distinct because they respond differently to certain environmental and physiological changes.

Pea fruit (Pisum sativum L.) is a model system for studying the effect of seeds on fruit growth in order to understand coordination of organ development. The metabolism of (14)C-labeled gibberellin A(12) (GA(12)) by pea pericarp was followed using a method that allows access to the seeds while maintaining pericarp growth in situ. Identification and quantitation of GAs in pea pericarp was accomplished by combined gas chromatography-mass spectrometry following extensive purification of the putative GAs. Here we report for the first time that the metabolism of [(14)C]GA(12) to [(14)C]GA(19) and [(14)C]GA(20) occurs in pericarp of seeded pea fruit. Removal of seeds from the pericarp inhibited the conversion of radiolabeled GA(19) to GA(20) and caused the accumulation of radiolabeled and endogenous GA(19). Deseeded pericarp contained no detectable GA(20), GA(1), or GA(8), whereas pericarp with seeds contained endogenous and radiolabeled GA(20) and endogenous GA(1). These data strongly suggest that seeds are required for normal GA biosynthesis in the pericarp, specifically the conversion of GA(19) to GA(20).

Gibberellins (GAs) are either required for, or at least promote, the growth of the pea (Pisum sativum L.) fruit. Whether the pericarp of the pea fruit produces GAs in situ and/or whether GAs are transported into the pericarp from the developing seeds or maternal plant is currently unknown. The objective of this research was to investigate whether the pericarp tissue contains enzymes capable of metabolizing GAs from [(14)C]GA(12)-7-aldehyde ([(14)C]GA(12)ald) to biologically active GAs. The metabolism of GAs early in the biosynthetic pathway, [(14)C]GA(12) and [(14)C]GA(12)ald, was investigated in pericarp tissue isolated from 4-day-old pea fruits. [(14)C]GA(12)ald was metabolized primarily to [(14)C]GA(12)ald-conjugate, [(14)C]GA(12), [(14)C]GA(53), and polar conjugate-like products by isolated pericarp. In contrast, [(14)C]GA(12) was converted primarily to [(14)C]GA(53) and polar conjugate-like products. Upon further investigations with intact 4-day-old fruits on the plant, [(14)C]GA(12) was found to be converted to a product which copurified with endogenous GA(20). Lastly, [(2)H]GA(20) and [(2)H]GA(1) were recovered 48 hours after application of [(2)H]- and [(14)C]GA(53) to pericarp tissue of intact 3-day-old pea fruits. These results demonstrate that pericarp tissue metabolizes GAs and suggests a function for pericarp GA metabolism during fruit growth.

It has been proposed that abscisic acid (ABA) may stimulate sucrose transport into filling seeds of legumes, potentially regulating seed growth rate. The objective of this study was to determine whether the rate of dry matter accumulation in seeds of soybeans (Glycine max L.) is correlated with the endogenous levels of ABA and sucrose in those sinks. The levels of ABA and sucrose in seed tissues were compared in nine diverse Plant Introduction lines having seed growth rates ranging from 2.5 to 10.0 milligrams dry weight per seed per day. At 14 days after anthesis (DAA), seeds of all genotypes contained less than 2 micrograms of ABA per gram fresh weight. Levels of ABA increased rapidly, however, reaching maxima at 20 to 30 DAA, depending upon tissue type and genotype. ABA accumulated first in seed coats and then in embryos, and ABA maxima were higher in seed coats (8 to 20 micrograms per gram fresh weight) than in embryos (4 to 9 micrograms per gram fresh weight. From 30 to 50 DAA, ABA levels in both tissues decreased to less than 2 micrograms per gram fresh weight. Levels of sucrose were also low early in development, less than 10 milligrams per gram fresh weight at 14 DAA. However, by 30 DAA, sucrose levels in seed coats had increased to 20 milligrams per gram fresh weight and remained fairly constant for the remainder of the filling period. In contrast, sucrose accumulated in embryos throughout the filling period, reaching levels greater than 40 milligrams per gram fresh weight by 50 DAA. Correlation analyses indicated that the level of ABA in seed coats and embryos was not directly correlated to the level of sucrose measured in those tissues or to the rate of seed dry matter accumulation during the linear filling period. Rather, the ubiquitous pattern of ABA accumulation early in development appeared to coincide with water uptake and the rapid expansion of cotyledons occurring at that time. Whole tissue sucrose levels in embryos and seed coats, as well as sucrose levels in the embryo apoplast, were generally not correlated with the rate of dry matter accumulation. Thus, it appears that, in this set of diverse soybean genotypes, seed growth rate was not limited by endogenous concentrations of ABA or sucrose in reproductive tissues.

Mefluidide, N-(2,4-dimethyl-5[([trifluoromethyl]sulfonyl) amino] phenyl)acetamide, a synthetic plant growth regulator, was capable of triggering an increase in endogenous free abscisic acid content when corn (Zea mays L.) plants were grown in a nonstress, day/night, temperature regime (26 degrees C) with sufficient moisture supply. The relevance of such an abscisic acid increase prior to chilling exposure and the water relations during chilling are discussed in reference to the mefluidide protection of the chilled corn plants.

Pea (Pisum sativum L. cv Alsweet) plants were exposed to mixtures of ozone plus sulfur dioxide at different times of the day. Injury, evaluated either as necrosis or chlorophyll, was greatest at midday when stomatal conductance was greatest. Abscisic acid levels were similar over the day, and showed no relation to stomatal conductance.

Cytokinins exported from the root may be involved in the correlative control of plant development. To test this hypothesis in soybean ((Glycine max [L.] Merr. cv. McCall, cv Chippewa 64, and cv Hodgson 78), cytokinins were intercepted en route from the root to the shoot by collecting root pressure exudate from detopped roots. The quantities of four cytokinins in the exudate were studied throughout the development of plants grown in the field and in controlled environment chambers. Zeatin, zeatin riboside, and their dihydro derivatives, dihydrozeatin and dihydrozeatin riboside, were isolated and quantitated using high-performance liquid chromatography.Cytokinin fluxes (pmoles per plant per hour) were independent of exudate flux (grams per plant per hour). All fluxes are averages for a 6- or 8-h collection period. The ribosides accounted for the majority of the observed cytokinin transport. The fluxes of zeatin riboside and dihydrozeatin riboside increased from low levels during vegetative growth to maxima during late flowering or early pod formation. Before the seeds began rapid dry matter accumulation, zeatin riboside and dihydrozeatin riboside fluxes decreased and remained at low levels through maturation. The fluxes of zeatin and dihydrozeatin were low throughout development.No correlation was found between cytokinin fluxes and nodule dry weight or specific nodule activity (acetylene reduction).The timing of distinct peaks in zeatin riboside and dihydrozeatin riboside fluxes during flowering or pod formation suggests that cytokinins exported from the root may function in the regulation of reproductive growth in soybean.

In G2 peas (Pisum sativum L.) apical senescence occurs only in long days (LD), and indeterminate growth is associated with elevated gibberellin (GA) levels in the shoot in short days (SD). Metabolism of GA(12) aldehyde was investigated by feeding shoots grown in SD or LD with [(14)C]GA(12) aldehyde through the cut end of the stem for 0.5 to 6 hours in the light and analyzing the tissue extract by high performance liquid chromatography. More radioactive products were detected than can be accounted for by the two GA metabolic pathways previously known to be present in peas. Three of the major products appear to be GA conjugates, but an additional pathway(s) of GA metabolism may be present. The levels of putative C(20) GAs, [(14)C]GA(53), [(14)C]GA(44), [(14)C]GA(19), and/or [(14)C] GA(17), were all elevated in SD as compared to LD. Putative [(14)C]GA, was slightly higher in LD than in SD. Putative [(14)C]GA(53) was a major metabolite after 30 minutes of treatment in SD but had declined after longer treatment times to be replaced by elevated levels of putative [(14)C] GA(44) and [(14)C]GA(19/17). Metabolism of GA(20) was slow in both photoperiods. Although GA(20) and GA(19) are the major endogenous GAs as determined by gas chromatography-mass spectrometry, putative [(14)C]GA(20) and [(14)C]GA(19) were never major products of [(14)C]GA(12) aldehyde metabolism. Thus, photoperiod acts in G2 peas to change the rate of GA(53) production from GA(12) aldehyde, with the levels of the subsequent GAs on the 13-OH pathway being determined by the amount of GA(53) being produced.

The distribution of abscisic acid (ABA) within maize (Zea mays L.) kernels was studied in kernels from nontreated plants, from plants in which assimilate supply had been altered by source/sink manipulations, and in kernels cultured in vitro on ABA-free media. Prior to growth of the embryo, both the pedicel/placento-chalazal complex and the endosperm contained high concentration of ABA; however, the quantity of ABA in these tissues declined as the concentration in the embryo increased during the early stages of embryo growth. Peaks in the levels of ABA appeared to occur prior to and not concurrent with physiological events during grain filling. During most of the grain filling period, ABA concentration in the embryo was higher than that found in other kernel components. Altering assimilate supply by partial defoliation at two stages of development resulted in variable and transient effects on the relative distribution and concentration of ABA in kernel components. The concentration and distribution of ABA among components of kernels grown in vitro was similar to that observed for field-grown kernels. On the basis of these findings, in situ synthesis of ABA by kernel components is implicated and the putative role of ABA in the regulation of kernel development is discussed.

A one-step, enzymatic assay for sucrose using sucrose phosphorylase is described. Sucrose phosphorylase, which is now commercially available, was isolated from Leuconostoc mesenteroides strain B-1200 and partially purified by ammonium sulfate precipitation. Samples containing 5 to 80 nmol of sucrose are mixed with potassium phosphate, NAD, sucrose phosphorylase, and two commercial enzymes, phosphoglucomutase and NAD-accepting glucose-6-phosphate dehydrogenase. After 30 min incubation at room temperature, absorbance at 340 nm is proportional to initial sucrose content. A 20-fold molar excess of glucose or a twofold excess of fructose have no effect on the assay, while a fourfold excess of fructose interferes with the assay by decreasing absorbance ca. 20%. This assay was designed to provide a rapid method for determining sucrose in studies of sugar transport by plants. To test the assay, corn pedicel extracts were assayed enzymatically and by high-pressure liquid chromatography. Estimates of sucrose content made by the two methods were equivalent, and exogenous addition of sucrose to these samples resulted in the expected increase in apparent sucrose content.

Photosynthetic rate, ribulose 1,5-bisphosphate carboxylase activity, specific leaf weight, and leaf concentrations of carbohydrates, proteins, chlorophyll, and inorganic phosphate were determined periodically from midbloom until maturity in leaves of soybean plants (Glycine max L., var. Hodgson) from which reproductive and vegetative sinks had been removed 32 hours before measurement, or continuously since midbloom.Leaf photosynthesis, measured in the top of the canopy, was partially inhibited by both sink removal treatments. This inhibition was of constant magnitude from midbloom until maturity.Leaf photosynthesis in the top of the canopy declined from midbloom until maturity in the control as well as in the desinked plants. The decline in photosynthesis was gradual at first, but later became more abrupt. The photosynthetic decline was equally evident in the yellowing leaves of control plants and in the dark green leaves of the continuously desinked plants.Neither the inhibition of photosynthesis by sink removal nor the decline in photosynthetic rate with time was clearly related to any of the measured traits.

Short-term transport studies were conducted using excised whole Zea mays kernels incubated in buffered solutions containing radiolabeled sugars. Following incubation, endosperms were removed and rates of net (14)C-sugar uptake were determined. Endogenous sugar gradients of the kernel were estimated by measuring sugar concentrations in cell sap collected from the pedicel and endosperm. A sugar concentration gradient from the pedicel to the endosperm was found. Uptake rates of (14)C-labeled glucose, fructose, and sucrose were linear over the concentration range of 2 to 200 millimolar. At sugar concentrations greater than 50 millimolar, hexose uptake exceeded sucrose uptake. Metabolic inhibitor studies using carbonylcyanide-m-chlorophenylhydrazone, sodium cyanide, and dinitrophenol and estimates of Q(10) suggest that the transport of sugars into the developing maize endosperm is a passive process. Sucrose was hydrolyzed to glucose and fructose during uptake and in the endosperm was either reconverted to sucrose or incorporated into insoluble matter. These data suggest that the conversion of sucrose to glucose and fructose may play a role in sugar absorption by endosperm. Our data do not indicate that sugars are absorbed actively. Sugar uptake by the endosperm may be regulated by the capacity for sugar utilization (i.e. starch synthesis).