Mean corpuscular volume as a prognostic factor for 30-day mortality in major trauma patients: a retrospective cohort study.

We investigated the clinical implications of the mean corpuscular volume (MCV) in patients with major trauma. This single-center retrospective review included 2021 trauma patients admitted to the intensive care unit between January 2016 and June 2020. We included 1218 patients aged [Formula: see text] 18 years with an injury severity score [Formula: see text] 16 in the final analysis. The clinical and laboratory variables were compared between macrocytosis (defined as MCV [Formula: see text] 100 fL) and non-macrocytosis groups. Cox regression analysis was performed to calculate the hazard ratios (HRs) of variables for 30-day mortality, with adjustment for other potential confounding factors. The initial mean value of MCV was 102.7 fL in the macrocytosis group (n = 199) and 93.7 fL in the non-macrocytosis group (n = 1019). The macrocytosis group showed a significantly higher proportion of initial hypotension, transfusion within 4 and 24 h, and 30-day mortality than the non-macrocytosis group. Age ([Formula: see text] 65 years), hypotension (systolic blood pressure [Formula: see text] 90 mmHg), transfusion (within 4 h), anemia (Hb < 12 g/day in women, < 13 g/day in men), and macrocytosis were significantly associated with 30-day mortality (adjusted HR = 1.4; 95% confidence interval 1.01-1.94; p = 0.046) in major trauma patients. Thus, initial macrocytosis independently predicted 30-day mortality in patients with major trauma at a Level I trauma center.

Successful endovascular treatment of an obstruction following the surgical repair of a traumatic portal vein injury: a case report.

Traumatic portal vein injury is rare, but the associated mortality rate ranges from 50% to 70%. The management of this injury is difficult and remains controversial. In this case report, we describe the successful endovascular treatment of an obstruction that developed following the surgical repair of a traumatic portal vein injury. A man in his mid-40s who had been injured in a car accident presented to our trauma center with abdominal pain, abdominal distension, and open wounds over both knees. Emergency laparotomy revealed a longitudinal rupture from the upper border of the pancreas to the mid-portion of the portal vein; his hemorrhage was successfully controlled surgically. However, postoperative abdominal computed tomography imaging revealed portal vein obstruction. One week after admission to the intensive care unit, an endovascular stent was successfully inserted into the patient's portal vein via a percutaneous transhepatic approach. The associated injuries, including the distal common bile duct obstruction, were successfully managed by choledochojejunostomy. The patient's postoperative recovery was uneventful. Thus, endovascular stent placement is an effective and safe means of treating an obstruction following the surgical repair of a traumatic portal vein injury.

Comparing machine learning and logistic regression for acute kidney injury prediction in trauma patients: A retrospective observational study at a single tertiary medical center.

Acute kidney injury (AKI) is common in patients with trauma and is associated with poor outcomes. Therefore, early prediction of AKI in patients with trauma is important for risk stratification and the provision of optimal intensive care unit treatment. This study aimed to compare 2 models, machine learning (ML) techniques and logistic regression, in predicting AKI in patients with trauma. We retrospectively reviewed the charts of 400 patients who sustained torso injuries between January 2016 and June 2020. Patients were included if they were aged > 15 years, admitted to the intensive care unit, survived for > 48 hours, had thoracic and/or abdominal injuries, had no end-stage renal disease, and had no missing data. AKI was defined in accordance with the Kidney Disease Improving Global Outcomes definition and staging system. The patients were divided into 2 groups: AKI (n = 78) and non-AKI (n = 322). We divided the original dataset into a training (80%) and a test set (20%), and the logistic regression with stepwise selection and ML (decision tree with hyperparameter optimization using grid search and cross-validation) was used to build a model for predicting AKI. The models established using the training dataset were evaluated using a confusion matrix receiver operating characteristic curve with the test dataset. We included 400 patients with torso injury, of whom 78 (19.5%) progressed to AKI. Age, intestinal injury, cumulative fluid balance within 24 hours, and the use of vasopressors were independent risk factors for AKI in the logistic regression model. In the ML model, vasopressors were the most important feature, followed by cumulative fluid balance within 24 hours and packed red blood cell transfusion within 4 hours. The accuracy score showed no differences between the 2 groups; however, the recall and F1 score were significantly higher in the ML model (.94 vs 56 and.75 vs 64, respectively). The ML model performed better than the logistic regression model in predicting AKI in patients with trauma. ML techniques can aid in risk stratification and the provision of optimal care.

Intestinal obstruction caused by small bowel entrapment within a lumbar fracture: A case report.

INTRODUCTION: Intestinal obstruction associated with traumatic vertebral fracture is extremely rare. We report a case of obstructive small bowel injury caused by entrapment of the small intestine at the fracture site of the 5th lumbar vertebra due to trauma. CASE PRESENTATION: A 55-year-old man fell from a height of 4 m and visited the emergency room of a local hospital with complain of back pain. During the examination, a 5th lumbar vertebral body fracture and left psoas muscle hematoma were observed, and the patient was admitted to the neurosurgery department for conservative treatment. The patient received conservative treatment for 2 days, but new symptoms of intestinal obstruction and fever occurred. A neurosurgeon at the hospital suspected duodenal perforation and transferred the patient to the regional trauma center for treatment. Our medical staff reviewed the patient's symptoms and imaging data and decided to perform an emergency operation because of small bowel entrapment in the 5th lumbar vertebrae fracture and perforation of the small intestine. We found that the small bowel, approximately 160 cm below the ligament of Treitz, was incarcerated at the 5th lumbar vertebral fracture site. After careful manual reduction of the entrapment of the small intestine, a small bowel resection of 25 cm, including the injury site, was performed with anastomosis. CONCLUSION: If symptoms of intestinal obstruction are observed in patients with traumatic spinal injury, medical staff must consider the exceedingly rare possibility of bowel entrapment.

Endovascular treatment of traumatic renal artery pseudoaneurysm with a Stanford type A intramural haematoma: A case report.

BACKGROUND: Aortic intramural hematoma (IMH) associated with aortic branch tear and intramurally located pseudoaneurysm after blunt trauma has not been reported. Here, we report a case of progressive type A aortic IMH associated with a pseudoaneurysm arising from the injured proximal renal artery after blunt trauma. CASE SUMMARY: During logging operations, a 66-year-old man experienced blunt force trauma after being injured by a fallen tree. He arrived at our trauma center with a left flank pain complaint. Computed tomography (CT) revealed a pseudoaneurysm arising from the proximal renal artery (localized within the aortic media) and Stanford type A IMH. A covered stent was deployed along the left main renal artery, bridging the pseudoaneurysm and covering the parent artery, successfully excluding the pseudoaneurysm as confirmed using aortography. However, although the degree of the pseudoaneurysm decreased, follow-up CT revealed remnant pseudoaneurysm, likely caused by an endoleak. Subsequently, a covered stent was additionally installed through the previously deployed covered stent. Successful exclusion of the pseudoaneurysm was confirmed using final aortography. In the 7-mo follow-up CT scan, the IMH and pseudoaneurysm completely disappeared with no evidence of stent-related complications. CONCLUSION: Endovascular treatment such as stent-graft placement can be an effective and safe treatment for traumatic renal artery injury.

Observational management of Grade II or higher blunt traumatic thoracic aortic injury: 15 years of experience at a single suburban institution.

Background: We aimed to investigate the outcomes after delayed management of ≥ Grade II blunt traumatic thoracic aortic injury (BTAI). Methods: Between January 2005 and December 2019, we retrospectively reviewed the medical records of 21 patients with ≥ Grade II thoracic aortic injury resulting from blunt trauma. Twelve patients underwent observation for the injury, whereas nine patients were transferred immediately after the diagnosis. Patients were divided into a nonoperative management group (n = 7) and delayed repair group (n = 5) based on whether they underwent thoracic endovascular aneurysm repair or surgery. Results: The most common dissection type was DeBakey classification IIIa (n = 9). Five patients underwent delayed surgery (including aneurysm repair), with observation periods ranging from 1 day to 36 months. The delayed repair group exhibited higher injury severity scores than the nonoperative management group (n = 7). The nonoperative management group was followed-up with blood pressure management without a change in status for a period ranging from 3 to 96 months. Conclusions: Our findings indicated that conservative management may be appropriate for select patients with Grade II/III BTAI, especially those exhibiting hemodynamic stability with anti-impulse therapy and minimally sized pseudoaneurysms. However, further studies are required to identify the risk factors for injury progression and long-term outcomes.

Successful treatment of symptomatic facet joint synovial cysts using C-arm fluoroscopy-guided percutaneous aspiration: report of two cases.

Lumbar facet-joint synovial cysts are an important cause of back pain and radiculopathy. Treatment options for facet-joint synovial cysts include surgical excision, facet-joint steroid injections, and facet-joint cyst aspiration. Although percutaneous facet-joint synovial cyst aspiration is an effective and minimally invasive procedure for treating patients with symptomatic facet-joint synovial cysts, its success rate is known to be low. Here, we report out experience with treating two men using this approach. The men presented with back pain or radiculopathy. In both cases, magnetic resonance imaging showed facet-joint synovial cysts in the lumbar spine at various locations. Depending on the location of the cysts, 2-3 needles and various needle approaches were required for treatment. The facet-joint synovial cysts were aspirated using the intra-articular, interlaminar, or safe triangle approach. After aspiration, both patients experienced immediate improvement in their symptoms, and neither of them relapsed during more than 12 months of follow-up. Percutaneous aspiration of symptomatic facet-joint synovial cysts under fluoroscopic guidance is a treatment option worth considering in patients with facet-joint synovial cysts.

Risk factors for ventilator-associated pneumonia in trauma patients with torso injury: a retrospective single-center study.

OBJECTIVE: We aimed to identify the risk factors for ventilator-associated pneumonia in patients admitted to critical care after a torso injury. METHODS: We retrospectively evaluated 178 patients with torso injury aged >15 years who were intubated in the emergency room and placed on a mechanical ventilator after intensive care unit (ICU) admission, survived for >48 hours, had thoracic and/or abdominal injuries, and had no end-stage renal disease. We compared clinico-laboratory variables between ventilator-associated pneumonia (n = 54, 30.3%) and non-ventilator-associated pneumonia (n = 124, 69.7%) groups. Risk factors for ventilator-associated pneumonia were assessed using multivariable logistic regression analysis. RESULTS: Ventilator-associated pneumonia was associated with a significantly longer stay in the ICU (11.3 vs. 6.8 days) and longer duration of mechanical ventilation (7 vs. 3 days). Injury Severity Score (adjusted odds ratio [AOR]: 1.048; 95% confidence interval [CI]: 1.008-1.090), use of vasopressors (AOR: 2.541; 95% CI: 1.121-5.758), and insertion of a nasogastric tube (AOR: 6.749; 95% CI: 2.397-18.999) were identified as independent risk factors of ventilator-associated pneumonia. CONCLUSION: Ventilator-associated pneumonia in patients with torso injury who were admitted to the ICU was highly correlated with Injury Severity Score, use of vasopressors, and insertion of a nasogastric tube.

Effect of clinical anesthesia preoperative evaluation on the length of preoperative period and total hospitalization of patients undergoing laparoscopic cholecystectomy.

OBJECTIVE: Anesthesia preoperative evaluation clinics (APECs) are currently operating in several South Korean hospitals. While several studies have investigated the impact of APEC operations on the length of total hospital stay (LTHS), few have investigated their impact on the length of preoperative hospital stay (LPHS) for patients. In this study, we aimed to determine whether APEC affected the LPHS and LTHS. METHODS: Data of all patients who underwent surgery at Chungbuk National University Hospital between September 2009 and August 2019 were analyzed retrospectively. All patients who had undergone laparoscopic cholecystectomy over the last 10 years were categorized into two groups: those who visited the APEC (Group A), and those who did not (Group B). The age, sex, American Society of Anesthesiologists physical status score, LPHS, and LTHS of the two groups were compared. RESULTS: The LPHS was 1.03±0.2 days in Group A and 1.61±1.6 days in Group B. The LTHS was 4.77±1.9 days in Group A and 5.63±2.6 days in Group B. The LPHS and LTHS of the two groups differed by 0.58 and 0.9 days, respectively. CONCLUSION: We evaluated the effect of APEC operations on the LPHS and LTHS of inpatients undergoing laparoscopic cholecystectomy and observed a decrease in both the LPHS and LTHS. Understanding and accepting the importance of APEC is significant for physicians and administrators working to improve hospital efficiency and patient outcomes. Further research is needed to investigate the need and benefits of APECs.

A rare case of acute meningitis shortly after lumbar selective nerve root block: a case report.

A 57-year-old man underwent lumbar selective nerve root block (SNRB) for low back pain and lower radiating pain caused by left-sided L4 disc herniation. He presented to the emergency department with fever, headache and aggravated low back pain approximately 3 hours after the procedure. Infection was suspected; hence, blood tests, cerebrospinal fluid (CSF) tests, lumbar magnetic resonance imaging, and brain computed tomography were performed. Imaging findings were not suggestive of infection. The CSF was turbid and yellowish with pleiocytosis; however, the CSF culture was negative. Based on these findings, the patient was diagnosed with acute meningitis. Broad-spectrum antibiotics and steroid therapy were initiated considering the patient's age and general condition. From hospital day (HD) 2, fever and headache were reduced and disappeared completely by HD 5. At the last follow-up, 1 month after discharge, the patient had no symptoms. Acute meningitis is associated with a high mortality and neurologic deficits. Hence, timely tests, diagnosis, and treatment are critical for positive outcomes. Symptoms of meningitis following a nerve block generally occur within 24-48 hours after the procedure. This case is notable, as it involved a quicker and more sudden onset of symptoms; meningitis occurred only a few hours after lumbar selective nerve root block.

Risk factors for acute kidney injury in critically ill patients with torso injury: A retrospective observational single-center study.

ABSTRACT: Acute kidney injury (AKI) is common in trauma patients and associated with poor outcomes. Identifying AKI risk factors in trauma patients is important for risk stratification and provision of optimal intensive care unit (ICU) treatment. This study identified AKI risk factors in patients admitted to critical care after sustaining torso injuries.We performed a retrospective chart review involving 380 patients who sustained torso injuries from January 2016 to December 2019. Patients were included if they were aged >15 years, admitted to an ICU, survived for >48 hours, and had thoracic and/or abdominal injuries and no end-stage renal disease. AKI was defined according to the Kidney Disease Improving Global Outcomes definition and staging system. Clinical and laboratory variables were compared between the AKI and non-AKI groups (n = 72 and 308, respectively). AKI risk factors were assessed using multivariate logistic regression analysis.AKI occurred in 72 (18.9%) patients and was associated with higher mortality than non-AKI patients (26% vs 4%, P < .001). Multivariate logistic regression analysis identified bowel injury, cumulative fluid balance >2.5 L for 24 hours, lactate levels, and vasopressor use (adjusted odds ratio: 2.953, 2.058, 1.170, and 2.910; 95% confidence interval: 1.410-6.181, 1.017-4.164, 1.019-1.343, and 1.414-5.987; P = .004, .045, .026, and .004, respectively) as independent risk factors for AKI.AKI in patients admitted to the ICU with torso injury had a substantial mortality. Recognizing risk factors at an early stage could aid risk stratification and provision of optimal ICU care.

Predictive role of vitamin B12 in acute kidney injury in living donor liver transplantation: a propensity score matching analysis.

OBJECTIVES: We examine the association between vitamin B12 level and risk for acute kidney injury (AKI) in patients undergoing living donor liver transplantation (LDLT). DESIGN: Retrospective observational cohort study. SETTING: University hospital, from January 2009 to December 2018. PARTICIPANTS: A total of 591 patients who underwent elective LDLT were analysed in this study. Those with a preoperative history of kidney dysfunction, vitamin B12 supplementation due to alcoholism, low vitamin B12 (<200 pg/mL) or missing laboratory data were excluded. PRIMARY AND SECONDARY OUTCOME MEASURES: The population was classified into AKI and non-AKI groups according to Kidney Disease Improving Global Outcomes (KDIGO) criteria, and associations between perioperative factors and AKI were analysed. After 1:1 propensity score (PS) matching, the association between high vitamin B12 (>900 pg/mL) and postoperative AKI was evaluated. RESULTS: Preoperative vitamin B12 was higher in the AKI group. Potentially significant perioperative factors from univariate analyses were entered into multivariate analyses, including preoperative factors (vitamin B12, diabetes), intraoperative factors (hourly urine output) and donor graft fatty change in LDLT patients. PS matching analyses with adjustment using PS revealed that high serum vitamin B12 (>900 pg/mL) was associated with risk for AKI, and the risk was 2.8-fold higher in patients with high vitamin B12 than in those with normal vitamin B12. Higher vitamin B12 was also related to a higher AKI stage. In addition, inflammatory factors (C reactive protein, white blood cells and albumin) were associated with vitamin B12 level. CONCLUSIONS: Our study may improve the accuracy of predicting postoperative AKI by introducing preoperative vitamin B12 into risk assessments for patients undergoing LDLT.

Associations of Serum Retinol and α-Tocopherol Levels with Uric Acid Concentrations: Analysis of a Population-Based, Nationally Representative Sample.

The effects of serum retinol and α-tocopherol on serum uric acid levels have not been established, especially in Asian people. This study evaluated the independent associations of retinol and α-tocopherol with serum uric acid levels in the Korean population. We included 6023 participants aged ≥ 19 years from the Korean National Health and Nutrition Examination Survey (KNHANES). Serum retinol and α-tocopherol levels were divided into quintiles, and a multivariate linear regression model was used to evaluate the association of serum retinol and α-tocopherol levels with uric acid concentration. Additionally, we used multivariate logistic regression to examine the relationships between the levels of these micronutrients and hyperuricemia. Serum retinol levels were positively associated with uric acid concentrations in a dose-dependent fashion in both sexes (ptrend < 0.001); the difference in serum uric acid levels between the highest and lowest quintiles of retinol levels was 0.57 mg/dL in men and 0.54 mg/dL in women. In the multivariable logistic model, the hyperuricemia risk increased linearly with the increase in serum retinol level, regardless of sex (ptrend < 0.001). Although the serum α-tocopherol level appeared to be significantly associated with increased uric acid levels, this association was nullified after adjusting for serum retinol levels. Serum retinol levels were positively associated with serum uric acid levels and hyperuricemia in a dose-response fashion. Maintaining serum retinol concentrations under sub-toxic levels might be necessary to prevent hyperuricemia-related adverse health outcomes.

Pneumatic Colorectal Injury Caused by High Pressure Compressed Air.

The pneumatic colorectal injury caused by high pressure compressed air are rare and can be fatal. Herein, we present a case of 45-year-old male who developed sudden onset of severe abdominal pain after cleaning the dust on his pants with high pressure compressed air gun dust cleaner. Emergent exploratory laparotomy was done which findings are a huge rectal perforation with multiple serosal and subserosal tear in sigmoid to splenic flexure of colon. Anterior resection with left hemicolectomy, and temporary transverse colostomy was performed. Postoperative course was uneventful. Recently, prognosis is generally favorable because of prompt diagnosis and emergent surgical management.

Right-sided diaphragmatic rupture in a poly traumatized patient.

Traumatic diaphragmatic rupture (TDR) is uncommon, and may be associated with other severe life-threatening injuries after blunt trauma. Recently, we experienced a right-sided TDR patient with other multiple life-threatening injuries. A 59-year-old female inflicted with a right-sided TDR accompanied by herniated liver was treated with thoracoscopic exploration. We successfully managed associated life-threatening injuries such as traumatic brain injury and pelvic bone fractures with bleeding, simultaneously.

Anodic WO3 mesosponge @ carbon: a novel binder-less electrode for advanced energy storage devices.

A novel design for an anodic WO3 mesosponge @ carbon has been introduced as a highly stable and long cyclic life Li-ion battery electrode. The nanocomposite was successfully synthesized via single-step electrochemical anodization and subsequent heat treatment in an acetylene and argon gas environment. Morphological and compositional characterization of the resultant materials revealed that the composite consisted of a three-dimensional interconnected network of WO3 mesosponge layers conformally coated with a 5 nm thick carbon layer and grown directly on top of tungsten metal. The results demonstrated that the carbon-coated mesosponge WO3 layers exhibit a capacity retention of 87% after completion of 100 charge/discharge cycles, which is significantly higher than the values of 25% for the crystalline (without carbon coating) or 40% for the as-prepared mesosponge WO3 layers. The improved electrochemical response was attributed to the higher stability and enhanced electrical conductivity offered by the carbon coating layer.

Synthesis and biological evaluation of 2'-substituted-4'-selenoribofuranosyl pyrimidines as antitumor agents.

The 2'-substituted-4'-selenoribofuranosyl pyrimidines 3a-3j were synthesized from D-ribose and assayed for anticancer activity. The 2'-azido and 2'-fluoro groups with a ribo configuration were introduced by the regioselective opening of the O2,2'-anhydronucleosides with sodium azide and (HF)x-pyridine, respectively. Among the compounds tested, only 2'-fluoro derivative 3j was found to exhibit significant anticancer activity, but was much less potent than the corresponding 2'-arabino analogue 2c. This study will provide medicinal chemists with the insight into the identification of structural requirements for the anticancer activity for the developments of biologically active nucleosides.

Comparative electrochemical analysis of crystalline and amorphous anodized iron oxide nanotube layers as negative electrode for LIB.

This work is a comparative study of the electrochemical performance of crystalline and amorphous anodic iron oxide nanotube layers. These nanotube layers were grown directly on top of an iron current collector with a vertical orientation via a simple one-step synthesis. The crystalline structures were obtained by heat treating the as-prepared (amorphous) iron oxide nanotube layers in ambient air environment. A detailed morphological and compositional characterization of the resultant materials was performed via transmission electron microscopy (TEM), field-emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), and Raman spectroscopy. The XRD patterns were further analyzed using Rietveld refinements to gain in-depth information on their quantitative phase and crystal structures after heat treatment. The results demonstrated that the crystalline iron oxide nanotube layers exhibit better electrochemical properties than the amorphous iron oxide nanotube layers when evaluated in terms of the areal capacity, rate capability, and cycling performance. Such an improved electrochemical response was attributed to the morphology and three-dimensional framework of the crystalline nanotube layers offering short, multidirectional transport lengths, which favor rapid Li(+) ions diffusivity and electron transport.

Structure-activity relationships of 2'-modified-4'-selenoarabinofuranosyl-pyrimidines as anticancer agents.

Based on the potent anticancer activity of the D-arabino-configured cytosine nucleoside ara-C, novel 2'-substituted-4'-selenoarabinofuranosyl pyrimidines 3a-3u, comprising azido, fluoro, and hydroxyl substituents at C-2' were designed, synthesized, and evaluated for anticancer activity. The 2'-azido group was stereoselectively introduced by the Mitsunobu reaction using diphenylphosphoryl azide (DPPA), and the 2'-fluoro group was stereoselectively introduced through the double inversions of stereochemistry via the episelenium intermediate, which was formed by the participation of the selenium atom. Among the compounds tested, the 2'-fluoro derivative 3t (X = NH2, Y = H, R = F) was found to be the most potent anticancer agent and showed more potent anticancer activity than the control, ara-C in all tested human cancer cell lines (HCT116, A549, SNU638, T47D, and PC-3) except the leukemia cell lines (K562). The anticancer activity of the 2'-substituted-4'-selenonucleosides is in the following order: 2'-F > 2'-OH > 2'-N3.

The effect of midazolam dose and age on the paradoxical midazolam reaction in Korean pediatric patients.

BACKGROUND: Although midazolam administration may occasionally induce a paradoxical episode, such as threatened crying and violent behavior in children, systematic studies on the causes of paradoxical reaction are limited. We investigated the effect of children's age and a dose of midazolam on the paradoxical reaction. METHODS: A total of one hundred sixty four children of 1-3 years and 3-5 years, were enrolled in this study. Each age group randomly received 0.05 mg/kg or 0.1 mg/kg of intravenous midazolam (41 patients/group). RESULTS: The incidence of paradoxical midazolam reaction in the study groups, 1-3 years with 0.1 mg/kg of intravenous midazolam, 1-3 years with 0.05 mg/kg, 3-5 years with 0.1 mg/kg, and 3-5 years with 0.05 mg/kg were as follows: 29.3%, 12.2%, 7.3% and 2.4%, respectively. The incidence among the 4 groups was significantly different (P = 0.002), highest in the 1-3 years receiving 0.1 mg/kg of midazolam (29.3%). Both age (P = 0.004, OR [95%CI] = 5.3 [1.7-16.8]) and dose of midazolam (P = 0.036, OR [95%CI] = 3.0 [1.1-8.4]) were risk factors. Perioperative clinical data including anxiety scales of children were not associated with the paradoxical midazolam reaction. CONCLUSIONS: In conclusion, we suggest that children less than 3 years old receiving higher dose of intravenous midazolam are at risk for the paradoxical midazolam reaction.