The potential for artificial intelligence to predict clinical outcomes in patients who have acquired acute kidney injury during the perioperative period.

Acute kidney injury (AKI) is a common medical problem in hospitalised patients worldwide that may result in negative physiological, social and economic consequences. Amongst patients admitted to ICU with AKI, over 40% have had either elective or emergency surgery prior to admission. Predicting outcomes after AKI is difficult and the decision on whom to initiate RRT with a goal of renal recovery or predict a long-term survival benefit still poses a challenge for acute care physicians. With the increasing use of electronic healthcare records, artificial intelligence may allow postoperative AKI prognostication and aid clinical management. Patients will benefit if the data can be readily accessed andregulatory, ethical and human factors challenges can be overcome.

Effect of Ultraviolet C Disinfection Treatment on the Nanomechanical and Topographic Properties of N95 Respirator Filtration Microfibers.

Ultraviolet germicidal irradiation (UVGI) N95 filtering facepiece respirator (FFR) treatment is considered an effective decontamination approach to address the supply shortage of N95 FFRs during the ongoing Covid-19 pandemic. In this study, we investigated the nanomechanical and topographic properties of filtration fibers that have been exposed to different doses of UVC radiation. UVC exposure was shown to decrease both Young's modulus (E), hardness (H) and fiber width, as measured on individual polypropylene (PP) fibers. Our results also show that the PP microfiber layer loses its strength when N95 respirators are exposed to an accumulated UVC dose during the process of decontamination, and the PP fiber width also exhibits a logarithmic decrease during UVC exposure. The nanoscale measurement results on individual fibers suggest that maximum cycles of UVC disinfection treatment should be limited due to excessive accumulated dose, which has the potential to decrease the fiber breaking strength.

Effects of Anticholinesterase Reversal Under General Anesthesia on Postoperative Cardiovascular Complications: A Retrospective Cohort Study.

BACKGROUND: The anticholinesterase neostigmine and the muscarinic inhibitor glycopyrrolate are frequently coadministered for the reversal of neuromuscular blockade. This practice can precipitate severe bradycardia or tachycardia, but whether it affects the incidence of cardiovascular complications remains unclear. We hypothesized that anticholinesterase reversal with neostigmine and glycopyrrolate versus no anticholinesterase reversal increases the risk of postoperative cardiovascular complications among adult patients undergoing noncardiac surgery with general anesthesia. METHODS: We conducted a prespecified retrospective analysis of hospital registry data from a major health care network for patients undergoing surgery with general anesthesia from January 2007 to December 2015. The primary outcome was a composite of cardiac dysrhythmia, acute heart failure, transient ischemic attack, ischemic stroke, and acute myocardial infarction within 30 days after surgery. We performed sensitivity analyses in subgroups and propensity score adjustment and explored the association between exposure and outcome in subgroups of patients with high risk of cardiovascular complications. RESULTS: Of the 98,147 cases receiving neuromuscular blockade, 73,181 (74.6%) received neostigmine and glycopyrrolate, while 24,966 (25.4%) did not. A total of 5612 patients (7.7%) in the anticholinesterase reversal group and 1651 (6.6%) in the control group (P < .001) experienced the primary outcome. After adjustment for clinical covariates, neostigmine and glycopyrrolate exposure was significantly associated in a dose-dependent fashion (P for trend <.001, respectively) with tachycardia (adjusted odds ratio = 2.1 [95% CI, 1.97-2.23]; P < .001) and bradycardia (adjusted odds ratio = 2.84 [95% CI, 2.49-3.24]; P < .001) but not with postoperative cardiovascular complications (adjusted odds ratio = 1.03 [95% CI, 0.97-1.1]; P = .33). We identified a significant effect modification of anticholinesterase reversal by high age, high-risk surgery, and history of atrial fibrillation (P for interaction = .002, .001, and .02, respectively). By using linear combinations of main effect and exposure-risk interaction terms, we detected significant associations between anticholinesterase reversal and cardiovascular complications toward a higher vulnerability in these patient subgroups. CONCLUSIONS: Neuromuscular blockade reversal with neostigmine and glycopyrrolate was associated with an increased incidence of intraoperative tachycardia and bradycardia but not with 30-day postoperative cardiovascular complications. Exploratory analyses suggest that a high postoperative cardiovascular complication risk profile may modify the effects of anticholinesterase reversal toward clinical relevance.

Extended Indications for Extracorporeal Membrane Oxygenation in the Operating Room.

BACKGROUND: The use of extracorporeal life support (ECLS) for cardiorespiratory support is increasing. Traditional absolute contraindications are currently deemed relative contraindications. Extracorporeal life support is now considered for a wider cohort of patients on a case-by-case basis. METHOD: We performed a review of the literature and examined current Extracorporeal Life Support Organization guidelines that support the use of ECLS in the operating room, based on the underlying pathology and surgical procedure proposed. We discuss specific surgical populations and different modes of ECLS and cannulation strategies. RESULTS: Based on the available literature, veno-venous extracorporeal membrane oxygenation (ECMO) can be used for the management of complex tracheobronchial and lung surgery, both in the elective and in the emergent setting. Elective veno-arterial (V-A) ECMO for cardiocirculatory support should be considered in high-risk patients undergoing ventricular tachycardia ablation. Extracorporeal life support should be considered as a potential life-saving intervention in almost all parturients with severe respiratory failure or refractory cardiogenic shock. V-A ECMO should be considered in unanticipated intraoperative cardiac arrest in patients without preexisting end-organ failure. CONCLUSION: As the number of indications for ECLS in the operating room is growing, anesthesiology and surgical staff should become familiar with the perioperative management of patients on ECLS.

The Effects of Postoperative Residual Neuromuscular Blockade on Hospital Costs and Intensive Care Unit Admission: A Population-Based Cohort Study.

BACKGROUND: Postoperative residual neuromuscular blockade continues to be a frequent occurrence with a reported incidence rate of up to 64%. However, the effect of postoperative residual neuromuscular blockade on health care utilization remains unclear. We conducted a retrospective cohort study to investigate the effects of postoperative residual neuromuscular blockade on hospital costs (primary outcome), intensive care unit admission rate, and hospital length of stay (secondary outcomes). METHODS: We performed a prespecified secondary analysis of data obtained in 2233 adult patients undergoing surgery under general anesthesia. Postoperative residual neuromuscular blockade was defined as a train-of-four ratio <0.9 in the postanesthesia care unit (PACU). Our confounder model adjusted for a variety of patient, surgical, and anesthesia-related factors. We fitted truncated negative binomial regression models for hospital cost and hospital length of stay analyses and a logistic regression model for our intensive care unit admission analysis. RESULTS: Overall, 457 (20.5%) patients in our cohort had residual neuromuscular blockade on admission to the PACU. Postoperative residual neuromuscular blockade was not independently associated with increased hospital costs (adjusted incidence rate ratio, 1.04, CI, 0.98-1.11; P = .22). There were significantly higher odds of intensive care unit admission in those with postoperative residual neuromuscular blockade compared to those without (adjusted odds ratio, 3.03, CI, 1.33-6.87; P < .01). Further, we found a trend toward increased hospital length of stay in patients with postoperative residual neuromuscular blockade (adjusted incidence rate ratio, 1.09; P = .06). Sensitivity analysis using the same model in the day of surgery admissions and ambulatory surgery confirmed our findings. CONCLUSIONS: Postoperative residual neuromuscular blockade at PACU admission was not significantly associated with increased hospital costs, but was associated with higher rates of intensive care unit admission. These findings support the view that clinicians should continue to work to reduce the rate of postoperative residual neuromuscular blockade.

Assessing biological effects of fluoxetine in developing zebrafish embryos using gas chromatography-mass spectrometry based metabolomics.

Continuous low-dose exposure of pharmaceutically active compounds (PhACs) in aquatic ecosystems is a concern worldwide. In this study, we utilized a gas chromatography mass spectrometry (GC-MS) based metabolomics approach to assess endogenous metabolite changes in developing zebrafish embryos exposed to different concentrations of the widely used antidepressant, fluoxetine. Embryos were exposed from 2 h post fertilization (hpf) until 96 hpf. Using the Fiehn GC-MS library, a total of 31 metabolites were positively identified in embryos. Statistical analyses revealed significant dysregulation of 11 metabolites in fluoxetine exposed embryos. Metabolite classes that were significantly altered included, amino acids, monosaccharides, glycerophosphates, fatty acids, carboxylic acid derivatives and sugars. Concentrations of amino acids, maltose, d-malic acid, 3-phosphoglycerate and d-glucose were significantly reduced in exposed embryos. Conversely, concentrations of citric acid were in some cases significantly elevated in exposed embryos. Metabolic pathway analysis revealed perturbation of five main pathways, including (i) alanine, aspartate and glutamate metabolism, (ii) phenylalanine, tyrosine and tryptophan biosynthesis, (iii) phenylalanine metabolism. (iv) tyrosine metabolism and (v) starch and sucrose metabolism. The results indicate fluoxetine exposure causes perturbation of energy and amino acid metabolism, which may adversely impact embryogenesis due to depletion of energy reserves during this period. Also, the observed alterations in aspartic acid, phenylalanine and tyrosine in fluoxetine exposed embryos suggests potential disruption of normal neurobehavioral and liver function. The results further demonstrate that GC-MS based metabolomics is an effective approach for assessing toxicodynamics and threshold effect levels of environmental pollutants in aquatic organisms.

Occurrence and distribution of halogenated flame retardants in an urban watershed: Comparison to polychlorinated biphenyls and organochlorine pesticides.

Due to restrictions on polybrominated diphenyl ethers (PBDEs), market demand for alternative flame retardants is projected to increase, worldwide. Information regarding the environmental behavior of these compounds is limited. The present study involved field measurements of several alternative halogenated flame retardants (HFRs), along with PBDEs and legacy persistent organic pollutants (POPs) in surface water, bottom sediments and suspended particulate matter (SPM) within a highly urbanized watershed in Singapore. Several alternative HFRs were detected in water and sediments. Dechlornane Plus stereoisomers (syn- and anti-DP) were detected in all samples, exhibiting relatively high concentrations in water, sediments and SPM. The maximum syn-DP concentrations in water, sediments and SPM were 24.30 ng/L, 2.48 ng/g dry wt. and 7774 ng/g dry wt., respectively. 1,2-Bis(2,4,6-tribromophenoxy) ethane (BTBPE), pentabromotoluene (PBT), hexabromobenzene (HxBBz) and tetrabromoethylcyclohexane (TBECH) were routinely detected. PBDE concentrations were relatively low and often non-detectable. Polychlorinated biphenyl (PCB) concentrations ranged from 0.017 to 8.37 ng/L in water, 9.86-27.92 ng/g dry wt. in SPM, and 6.48-212.3 ng/g dry wt. in sediments. Congener and isomer patterns suggested no recent inputs of PBDEs or dichlorodiphenyltrichloroethane (DDT). Rainfall was found to be an important factor influencing temporal and spatial patterns of DPs, BTBPE, PBDEs and some organochlorines in surface water. Land use index was found to be important for several organochlorines, but not HFRs. The observed sediment-water partitioning behavior of the studied HFRs and legacy POPs was highly dependent on chemical hydrophobicity. The data demonstrate that the studied HFRs have a relatively high affinity for SPM and bottom sediments. For example, the log KOC,OBS for TBECH, syn-DP and anti-DP and BTBPE in bottom sediments ranged between 8.1 and 9.6. The findings will aid future studies regarding fate, transport and bioaccumulation of these current-use contaminants of concern.

How to better identify patients at high risk of postoperative complications?

PURPOSE OF REVIEW: Preoperative risk assessment and perioperative factors may help identify patients at increased risk of postoperative complications and allow postoperative management strategies that improve patient outcomes. This review summarizes historical and more recent scoring systems for predicting patients with increased morbidity and mortality in the postoperative period. RECENT FINDINGS: Most prediction scores predict postoperative mortality with, at best, moderate accuracy. Scores that incorporate surgery-specific and intraoperative covariates may improve the accuracy of traditional scores. Traditional risk factors including increased ASA physical status score, emergent surgery, intraoperative blood loss and hemodynamic instability are consistently associated with increased mortality using most scoring systems. SUMMARY: Preoperative clinical risk indices and risk calculators estimate surgical risk with moderate accuracy. Surgery-specific risk calculators are helpful in identifying patients at increased risk of 30-day mortality. Particular attention should be paid to intraoperative hemodynamic instability, blood loss, extent of surgical excision and volume of resection.

Chlorinated Polyfluoroalkyl Ether Sulfonic Acids in Matched Maternal, Cord, and Placenta Samples: A Study of Transplacental Transfer.

Currently, information regarding concentrations of chlorinated polyfluoroalkyl ether sulfonic acids (Cl-PFESAs) in human placenta does not exist. The main objective of this study was to assess the occurrence and distribution of two Cl-PFESAs, 6:2 Cl-PFESA and 8:2 Cl-PFESA, in maternal serum, umbilical cord serum, and placenta to better assess the transport pathways related to human prenatal exposure. The widely studied perfluorooctanesulfonate (PFOS) was studied for comparison. This study was a hospital-based survey involving quantitative determination of Cl-PFESA and PFOS concentrations in maternal serum (n = 32), cord serum (n = 32), and placenta (n = 32) samples from women in Wuhan, China. The results indicate that Cl-PFESAs can efficiently be transported across placenta, with median exposure levels of 0.60 and 0.01 ng/mL for 6:2 Cl-PFESA and 8:2 Cl-PFESA in the cord sera, respectively. Concentrations of the target compounds in maternal sera, cord sera, and placentas decreased in the following order: PFOS > 6:2 Cl-PFESA > 8:2 Cl-PFESA. Similar patterns were observed in maternal sera, cord sera, and placentas for Cl-PFESAs, with concentrations decreasing in the following order: maternal sera > cord sera > placentas. Significant correlations were observed among 6:2 Cl-PFESA, 8:2 Cl-PFESA, and PFOS concentrations in the maternal serum, cord serum, and placenta samples (r > 0.7; p < 0.001). The median value of RCM (ratio of cord serum to maternal serum concentration) of 6:2 Cl-PFESA was 0.403, indicating a relatively high (∼40%) placental transfer efficiency. 8:2 Cl-PFESA was transported across placenta to a greater extent than 6:2 Cl-PFESA was, likely because of its higher hydrophobicity and lower plasma protein binding affinity. To the best of our knowledge, this is the first study to report the occurrence and distribution of 6:2 Cl-PFESA and 8:2 Cl-PFESA in human placenta. The findings improve our understanding of the mechanisms of transplacental transfer and neonatal exposure to these important PFOS alternatives.

Associations of serum organohalogen levels and prostate cancer risk: Results from a case-control study in Singapore.

There is increasing evidence that elevated exposure to organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) may lead to an increased risk of prostate cancer. As part of a hospital-based case-control study of the Singaporean male population, we investigated associations between organohalogen exposure and risk of prostate cancer. Trace residue concentrations of 74 organohalogen contaminants, including several PCBs, OCPs and halogenated flame retardants (HFRs), were determined in serum samples (n = 120) using gas chromatography tandem mass spectrometry (GC-MS/MS). A variety of OCPs, PCBs and HFRs were detected in samples of both patients and controls. Mean concentrations of p,p' DDT, p,p' DDE, PCB 118, PCB 138, PCB 153 and PCB 187 were significantly higher (p < 0.05) in serum of patients. p,p' DDE measured in serum of patients was relatively high (mean:13,700 ng/g lipid, 95% CI:7000-26,800). Odds ratios (ORs) of OCPs and PCBs in many cases exceeded 1. ORs for p,p' DDE and PCB-153 at the highest tertile (>67th) were 5.67 (95% CI, 2.37-13.54) and 2.14 (95% CI, 0.99 to 4.66), respectively. The results suggest that exposure to DDTs and PCBs may be associated with prostate cancer risk in Singaporean males. No such association was observed for the organohalogen flame retardants studied, including polybrominated diphenyl ethers (PBDEs). The study provides novel information regarding the occurrence, levels and potential associations with prostate cancer risk for several organohalogen contaminants in the Singapore population. However, further investigation and analyses should be conducted to confirm these findings.

Multi-residue analysis of legacy POPs and emerging organic contaminants in Singapore's coastal waters using gas chromatography-triple quadrupole tandem mass spectrometry.

A gas chromatography-triple quadrupole mass spectrometry (GC-MS/MS) based method was developed for determination of 86 hydrophobic organic compounds in seawater. Solid-phase extraction (SPE) was employed for sequestration of target analytes in the dissolved phase. Ultrasound assisted extraction (UAE) and florisil chromatography were utilized for determination of concentrations in suspended sediments (particulate phase). The target compounds included multi-class hydrophobic contaminants with a wide range of physical-chemical properties. This list includes several polycyclic and nitro-aromatic musks, brominated and chlorinated flame retardants, methyl triclosan, chlorobenzenes, organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs). Spiked MilliQ water and seawater samples were used to evaluate the method performance. Analyte recoveries were generally good, with the exception of some of the more volatile target analytes (chlorobenzenes and bromobenzenes). The method is very sensitive, with method detection limits typically in the low parts per quadrillion (ppq) range. Analysis of 51 field-collected seawater samples (dissolved and particulate-bound phases) from four distinct coastal sites around Singapore showed trace detection of several polychlorinated biphenyl congeners and other legacy POPs, as well as several current-use emerging organic contaminants (EOCs). Polycyclic and nitro-aromatic musks, bromobenzenes, dechlorane plus isomers (syn-DP, anti-DP) and methyl triclosan were frequently detected at appreciable levels (2-20,000pgL(-1)). The observed concentrations of the monitored contaminants in Singapore's marine environment were generally comparable to previously reported levels in other coastal marine systems. To our knowledge, these are the first measurements of these emerging contaminants of concern in Singapore or Southeast Asia. The developed method may prove beneficial for future environmental monitoring of hydrophobic organic contaminants in marine environments. Further, the study provides novel information regarding several potentially hazardous contaminants of concern in Singapore's marine environment, which will aid future risk assessment initiatives.

Overview of the investigation and management of cystic neoplasms of the pancreas.

BACKGROUND: Cystic neoplasms of the pancreas contribute to 10-20% of pancreatic tumours. Malignant cystic tumours of the pancreas behave similar to adenocarcinomas and thus warrant aggressive management. However, certain benign cystic neoplasms do not require operative intervention. It is, therefore, important to differentiate benign lesions from malignant lesions and from those with malignant potential. AIMS: To provide an overview of the role of radiological investigations in the management of cystic neoplasms of the pancreas, with emphasis on the characteristic features of aggressive tumours. The role of different imaging modalities is discussed, and an investigative algorithm suggested. METHODS: A literature review was carried out on Medline, Cochrane library, and PubMed using the MeSH terms 'pancreas' and 'cysts' to source relevant papers. Search criteria were limited to English literature, meta-analyses, systematic reviews, prospective and retrospective case series, published during or after 1998. DISCUSSION: Each pancreatic cystic lesion has characteristic radiological findings. However, the diagnostic accuracy of individual imaging techniques is still limited. A combination of imaging modalities is essential for preoperative diagnosis. CT complemented by endoscopic ultrasound and cyst fluid analysis appears to be the most promising investigation in diagnosing cystic neoplasms. Follow-up with serial imaging is useful for lesions of uncertain aetiology.

Flesh residue concentrations of organochlorine pesticides in farmed and wild salmon from British Columbia, Canada.

The present study reports measured levels of organochlorine pesticides (OCPs) in commercial salmon feed (n = 8) and farmed Atlantic, coho, and chinook salmon (n = 110), as well as wild coho, chinook, chum, sockeye, and pink salmon (n = 91). Flesh residue concentrations (ng/g wet weight) of dichlorodiphenyltrichloroethanes (DDTs), hexachlorocyclohexanes (HCHs), chlordanes, chlorobenzenes (CBz) and cyclodiene pesticides (e.g., dieldrin, mirex) were 2 to 11 times higher (p < 0.05) in farmed salmon compared with wild salmon. Concentrations were positively correlated with flesh lipid levels. Farmed Atlantic salmon (12-15% lipid) typically exhibited the greatest OCP burdens compared with other salmon species. However, when expressed on a lipid weight basis, concentrations of OCPs (ng/g lipid weight) in wild salmon, in many cases, exceeded those levels in farmed salmon. Observed interspecies and site-specific variations of OCP concentrations in farmed and wild salmon may be attributed to divergent life history, prey/feed characteristics and composition, bioenergetics, or ambient environmental concentrations. Calculated biomagnification factors (BMF = C(F)/C(D), lipid wt) of OCPs in farmed salmon typically ranged between two and five. Biomagnification of chemicals such as DDTs, chlordanes, and mirex was anticipated, because those compounds tend to exhibit high dietary uptake and slow depuration rates in fish because of relatively high octanol-water partition coefficients (K(OW)s > 105). Surprisingly, less hydrophobic pesticides such as hexachlorocyclohexanes and endosulfans (K(OW) s < 105) consistently exhibited a high degree of biomagnification in farmed salmon species (BMFs > 5). This is contrary to previous laboratory and field observations demonstrating fish BMFs less than 1 for low K(OW) chemicals, because of efficient respiratory elimination of those compounds via gills. The results suggest that ambient seawater concentrations and bioconcentration-driven accumulation may play a key role in the bioaccumulation of these relatively more water-soluble contaminants in farmed salmon. Finally, OCP exposure through consumption of British Columbian salmon is found to be low relative to United States national average per capita total exposure levels and provisional tolerable daily intakes.

Assessment of VIE image quality using helical CT angiography: in vitro phantom study.

The aim of this study is to quantify the effects of helical CT acquisitions parameters on the magnitude of three-dimensional stair-step artefacts, visualization of renal ostium and morphologies of suprarenal stents observed using virtual intravascular endoscopy. This was performed in a phantom of the human abdominal aorta with a stent graft in situ. Stair-step artefacts were quantified by measuring the standard deviation of signal intensity on surface shaded images and the influence of these artefacts on the visualization of arterial ostia and stent morphologies were assessed by three radiologists. The methodology may be used to optimise the CT system performance for helical CT angiography in aortic stent grafting.

Diagnostic value of CT virtual intravascular endoscopy in aortic stent-grafting.

PURPOSE: To investigate the diagnostic value of postprocessing techniques for 3-dimensional (3D) computed tomography (CT), with emphasis on CT virtual intravascular endoscopy (VIE), in patients with abdominal aortic aneurysms (AAA) treated with suprarenal stent-grafts. METHODS: The preprocedural and postprocedural CT datasets from 47 AAA patients (40 men; mean age 75 years, range 61-87) undergoing aortic stent-grafting with suprarenal fixation were examined. The CT datasets were processed to create various 3D reconstructions: shaded surface display (SSD), maximum intensity projection (MIP), and VIE. Three independent radiologists assessed various diagnostic parameters for each 3D reconstruction method and compared them to axial CT images. RESULTS: Scores for VIE reconstructions were inferior to axial CT images in the visualization of normal arterial branches, measurement of the aneurysm diameter and neck length, as well as assessment of vessel patency and presence of endoleaks. VIE was rated superior to axial CT and other 3D imaging methods in visualizing the configuration of stent struts relative to the aortic branch ostia and the number of stent wires crossing the ostia in >80% of cases. CONCLUSIONS: VIE was not found to play a role in most preoperative situations compared to axial CT images. However, VIE provided additional postgrafting information on the 3D relationship of the suprarenal stent struts to the aortic branch ostia (in particular the renal and superior mesenteric arteries). VIE findings might aid clinicians in accurately assessing the effect of suprarenal stent-grafting on the renal arteries.

Sputum retention after lung operation: prospective, randomized trial shows superiority of prophylactic minitracheostomy in high-risk patients.

BACKGROUND: Sputum retention after lung operation is a potentially life-threatening condition. The minitracheostomy (Minitrach II, SIMS Portex, Hythe, Kent, UK) is a 4-mm percutaneous cricothyroidotomy device, which allows immediate and repeated aspiration of the tracheobronchial tree by minimally trained staff, and can effectively treat sputum retention. This trial was designed to test the hypothesis that prophylactic minitracheostomy could prevent sputum retention in a high-risk group. METHODS: Between March 1997 and October 1999, 102 patients undergoing lung procedures and considered to be at high risk were prospectively randomized to postoperative, prophylactic minitracheostomy insertion in the recovery room with regular aspiration, or to standard postoperative respiratory therapy. RESULTS: Sputum retention developed in 15 patients (30%) in the standard group (n = 52) compared to 1 patient (2%) in the minitracheostomy group (n = 50) (p < 0.005). There were three deaths related to sputum retention in the standard group compared to none in minitracheostomy group during the perioperative period. CONCLUSIONS: It is possible to identify a group of patients at high risk for sputum retention who will benefit from prophylactic therapy. Minitracheostomy is effective as prophylaxis and treatment.