Correlation of TIRADS scoring in thyroid nodules with preoperative fine needle aspiration biopsy and postoperative specimen pathology.

INTRODUCTION: The aim of our study is to determine the value of Thyroid Imaging Reporting and Data Systems (TIRADS) scoring in predicting malignancy in thyroid nodules by examining its relationship with fine needle aspiration biopsy and postoperative histopathological results. MATERIALS AND METHODS: In this study, patients who underwent surgery after ultrasonographic examination and fine needle aspiration biopsy for thyroid nodules at the General Surgery Clinic of Çukurova University Faculty of Medicine between January 2014 and November 2021 were retrospectively analyzed. The thyroid ultrasonography and fine needle aspiration biopsy of the included patients were performed by a clinician with 15 years of experience. The ultrasonographic features of the nodules were re-evaluated by the same clinician, and the American College of Radiology (ACR) TIRADS score was determined. Fine needle aspiration biopsy results were grouped according to Bethesda criteria. Postoperative histopathological examination results were divided into two groups: benign and malignant. The ACR TIRADS score was compared with fine needle aspiration biopsy and histopathological results. The performance of the ACR TIRADS score in predicting malignancy was determined. RESULTS: 79.8% of the 397 patients were female, and the mean age was 50.9 ± 12.8 years. The mean diameter of the nodules was 27.4 ± 15.8 mm. There was a significant, positive, but weak correlation between ACR TIRADS and Bethesda (p < 0.001) (r = 0.33). When the ACR TIRADS score was compared with histopathological results, it was found that the rate of malignancy increased as the TIRADS score increased (p < 0.001). The rates of malignancy diagnosis were 0% for TR1, 13.2% for TR2, 21.7% for TR3, 50.3% for TR4, and 72.4% for TR5. The area under the receiver operating characteristic curve for TIRADS in predicting malignancy was 0.747 (95% CI: 0.699-0.796, p < 0.001). TIRADS can distinguish malignancy with 75% accuracy. The optimal cutoff point was determined as TR4 with 80.3% sensitivity and 60.8% specificity. CONCLUSION: The ACR TIRADS scoring system is an effective risk classification system for thyroid nodules, providing 75% accuracy in predicting malignancy, with 80.3% sensitivity and 60.8% specificity values.

Preoperative Immunonutrition and Postoperative Outcomes in Radical Pancreaticoduodenectomy Patients.

BACKGROUND/AIMS: This study aimed to compare the patient groups who received and did not receive immunonutrition in terms of mortality and morbidity in patients who underwent radical pancreaticoduodenectomy. MATERIALS AND METHODS: Two groups were formed from 40 patients who underwent radical pancreaticoduodenectomy in our clinic in 2021. The patients in study group were given enteral immunonutrition support for 5 days preoperatively. For this purpose, a standard enteral immunonutrition product containing arginine, omega-3 fatty acids, and RNA (dietary nucleotides) was used. Patients' data of demographical, laboratory, postoperative complications, and current clinical status were analyzed. RESULT: Mortality developed in 5 (25 %) patients in the treatment group and 4 (20 %) patients in the control group in the following months (P > .05). The estimated survival rate in the treatment group was 21.8 ± 2.8 months in the treatment group 19.1 ± 1.7 months in the control group (P > .05). The length of hospital stay was 12.89 ± 3.3 days in the treatment group, while it was 16.47 ± 6.83 days in the control group (P < .05). In the postoperative follow-ups, delayed gastric emptying symptoms developed in 3 patients in the treatment group, while the same complication was observed in 9 patients in the control group (P < .05). Surgical site infections occurred in 4 patients in the treatment group and 9 patients in the control group (P < .05). CONCLUSION: It was observed that preoperative oral immunonutrition before pancreaticoduodenectomy was effective in reducing the risk of delayed gastric emptying after surgery and the length of hospital stay.

The Effect of Preoperative Fear of Pain on Postoperative Pain Levels and the Amount of Analgesic Consumption.

BACKGROUND: Preoperative fear of pain can increase the surgical stress response along with anxiety, increasing postoperative pain and the amount of analgesia consumption. AIMS: To determine the effect of preoperative fear of pain on postoperative pain level and analgesic consumption. DESIGN: A descriptive, cross-sectional design was used. METHODS: A total of 532 patients who were scheduled for a variety of surgical procedures in a tertiary hospital were included in the study. Data were collected using Patient Identification Information Form and Fear of Pain Questionnaire-III. RESULTS: 86.1% of the patients thought that they would experience postoperative pain, and 70% of the patients reported moderate-to-severe postoperative pain. The examination of the postoperative first 24-hour pain levels indicated that there was a significant positive correlation between patients' pain levels within 0-2 hours and their mean scores on the fear of severe and minor pain sub-dimensions and the total scale and between pain experienced within 3-8 hours and their scores on the fear of severe pain sub-dimension (p <.05). Also, a significant positive correlation was found between patients' mean scores on the total fear of pain scale and the amount of nonopioid (diclofenac sodium) consumption (p <0.05). CONCLUSIONS: The fear of pain increased patients' postoperative pain levels, and thus the amount of analgesic consumption. Therefore, patients' fear of pain should be determined in the preoperative period, and pain management practices should be initiated in this period. As a matter of fact, effective pain management will positively affect patient outcomes by reducing the amount of analgesic consumption.

Complete mesocolic malposition of the gallbladder: An unusual case report with literature's review.

Anatomic variations and congenital anomalies involving the gallbladder position, shape, and number are frequently encountered on routine abdominal imagings and at surgery. However, most have no clinical significance, but their recognition is important because they may predispose to gallbladder diseases, serve as a potential source of confusion and diagnostic pitfalls for radiologists and surgeons, and increase the risk of inadvertent injury during biliary tract surgery or intervention. We observed an intra-mesocolic gallbladder found unexpectedly during the cholecystectomy in a 65-year-old male patient who was being operated on for acute calculous cholecystitis. An abdominal ultrasonography and computed tomography scan reported no anomalous or malpositioned gallbladder pre-operatively. As the location of this organ could not be definitely clarified in his previous operation elsewhere, we performed an explorative lapa-rotomy. There was no gallbladder at the normal position. The organ was found embedded deeply within the proximal portion of the transverse mesocolon, and then it was successfully excised. We established the diagnosis of an ectopic gallbladder in mesocolic position.

Migration of Tenckhoff Catheter to Sigmoid Colon: A Rare Delayed Complication.

Bowel perforation associated with inserted peritoneal dialysis (PD) catheter mainly occurs during the perioperative period. Delayed bowel perforation is difficult to diagnose because of its different clinical signs and rarity. A 53-year-old woman developed acute abdomen after her PD catheter was changed. It was found that the changed catheter perforated the sigmoid colon. Primary repair of the perforated area of the sigmoid colon was performed, and the last inserted PD catheter was removed. The postoperative period and recovery were uneventful. Perforations due to the PD catheter may remain silent until the catheter is replaced. In patients with frequent episodes of peritonitis, a perforation area due to PD catheter which limited itself should be considered as the etiology.

Modified techniques versus Hadfield's procedure in patients with periductal mastitis.

BACKGROUND: Periductal mastitis (PM) is a rare disease characterized by chronic inflammation of the terminal mammary ducts. Complete removal of terminal lactiferous ducts with Hadfield procedure is a previously defined technique in treatment but carries various complications risks. This study aims to evaluate the effectiveness of modified techniques in the treatment of PM. METHODS: Twenty women who underwent surgery due to PM between January 2012 and December 2019 were retrospectively analyzed. Types of PM were determined. All patients were operated on with three different incisions [Hadfield's operation with periareolar incision (n:11), periareolar combined radial incision (n:7), and round block incision (n:2)]. RESULTS: The mean age was 37.5 ± 6.5 years (range: 24-49). Sixty percent of patients had type 3 PM. In Hadfield's procedure, NAC retraction (n:2), seroma (n:1), and hematoma (n:1) were seen. In the periareolar incision combined radial incision group only one patient had complications (seroma) and none in the round block method. Follow-up was 12 ± 1.5 months and disease relapse occurred in two patients in the Hadfield group. Patients who underwent round block were more satisfied with the appearance of the nipple. CONCLUSIONS: In the treatment of PM, the main principle of surgical treatment is the excision of the affected canal with a clear margin. Apart from the classical Hadfield procedure, the round block method and periareolar combined radial incision techniques can be performed in the treatment of PM.

The usefulness of drainage-internal capitonnage with/without selective bile duct repair technique for liver hydatid cyst.

PURPOSE: The aim of the present study is to describe the cavity-reducing internal capitonnage technique that we used for the surgical therapy of liver hydatid cyst, and contribute to the literature by presenting the short- and long-term outcomes of the patients who were operated on with this technique. METHODS: A drainage and internal capitonnage technique was performed on 12 cases due to liver hydatid cyst in our clinic between January 2016 and December 2019. RESULTS: The mean age of cases was 36.25 ± 12.5 years, with 7 females and 5 males. All cases had pain in the right upper quadrant, and a sense of fullness in 5 cases. None of the cases had ruptured cysts, jaundice, or other clinical manifestations. The preoperative laboratory findings were normal in 8 cases. Intraoperative biliary-cyst communication was demonstrated in 8 cases (66.7%). Cases were followed up for a mean duration of 38.1 months (range, 24-88 months). CONCLUSION: The drainage/internal capitonnage with/without selective bile duct repair is a technique that can be performed with very low morbidity and mortality rates in experienced hands, especially for centrally located hydatid cysts.

Xanthogranulomatous cholecystitis: a rare gallbladder pathology from a single-center perspective.

PURPOSE: The aim of this study was to review patients with xanthogranulomatous cholecystitis (XGC). METHODS: A total of 79 patients diagnosed with XGC were included in the study. The criteria for XGC in the pathology specimens were the presence of histiocytes, cholesterol deposits, lipids, and focal or widespread wall enlargement. RESULTS: Patients were diagnosed with XGC, of which 52 (65.8%) were male and 27 (34.2%) were female, creating a male-to-female ratio of 2:1. The mean age was 65.8 ± 14.3 years (range, 36-97 years). The most common presenting symptom was abdominal pain (63.3%), and the least common presenting symptom was jaundice (8.9%). Of the total, 25 patients were found to have pathological conditions with the potential to obstruct the bile duct or to slow bile flow. A frozen section examination was performed on 20 patients due to suspicion of a tumor by intraoperative macroscopic examination. However, no malignancy was detected in the cases who underwent a frozen section examination. An increase in wall thickness of the gallbladder was observed in 81.6% (n = 31) of the patients on computed tomography scans and in 81.8% (n = 18) of the patients on magnetic resonance imaging scans in which possible tumor lesions were reported, but no tumor was detected. CONCLUSION: It is difficult to diagnose XGC either preoperatively or intraoperatively, and further imaging methods are needed in the preoperative period other than ultrasonography. However, a definitive diagnosis depends exclusively on pathologic examination.

The efficacy of 18F-FDG PET/CT in the preoperative evaluation of pancreatic lesions.

PURPOSE: Since the treatment strategy for benign and malignant pancreatic lesions differ, we aimed to evaluate the clinical value of PET/CT in the diagnosis and management of pancreatic lesions. METHODS: Ninety patients who had a histologically confirmed pancreatic lesion were studied. Receiver operating characteristic (ROC) curve analysis was used to investigate the ability of PET/CT to differentiate malignant lesions from benign tumors. RESULTS: The malignant and benign groups comprised 64 and 26 patients, respectively. Despite the similarity in the size of primary tumors (P = 0.588), the mean maximum standardized uptake values (SUVmax) obtained from PET/CT imaging were significantly higher in malignant lesions (9.36 ± 5.9) than those of benign tumors (1.04 ± 2.6, P < 0.001). ROC analysis showed that the optimal SUVmax cutoff value for differentiating malignant lesions (to an accuracy of 91%; 95% confidence interval, 83%-98%) from benign tumors was 3.9 (sensitivity, 92.2%; specificity, 84.6%). CONCLUSION: PET/CT evaluation of pancreatic lesions confers advantages including fine assessment of malignant potential with high sensitivity and accuracy using a threshold SUVmax value of 3.9.

Hemosuccus pancreaticus A case report and review of the literature.

Hemosuccus pancreaticus is a rare clinical condition, defined as a bleeding from an artery around the pancreas or a lesion on the pancreas, to the pancreatic duct. The intensity of bleeding can vary from occult bleeding to life threatening massive acute bleeding. In this article, we aimed to present a 68-year-old man who presented to our clinic with recurrent upper gastrointestinal bleeding and abdominal pain. Endoscopy revealed hemorrhage from ampulla vateri, CT angiographic examination showed an aneurysm of the splenic artery and that the splenic artery was connected to the pancreatic duct.Splenectomy and subtotal pancreatectomy was performed on the patient. The patient was discharged with healing. Hemosuccus pancreaticus should be kept in mind in patients with a history of pancreatitis and peripancreatic aneurysm and upper gastrointestinal bleeding.The early diagnosis and treatment of HP is life-saving. In this study, we aimed to review the basic symptoms and clinical findings, along with the diagnosis and treatment methods of HP. KEY WORDS: Gastrointestinal bleeding, Pancreas, Splenic Artery.

Intractable external pancreatic fistula post-necrosectomy treated successfully with a fistulojejunostomy.

Pancreatic fistula formation is a known complication of pancreatic surgery, pancreatitis, and pancreatic injury. We here report a case of a 65-year-old man who was diagnosed with gallstone-induced acute pancreatitis with walledoff pancreatic necrosis. The patient initially underwent medical treatment and percutaneous drainage at 4 weeks. After a four-week period, a formal laparotomy with necrosectomy, and the catheter drainage of the cavity were performed. Having postoperatively developed a pancreatic fistula, the patient was managed conservatively. After 6 weeks of medical treatment, patient underwent an endoscopic retrograde pancreatography and was diagnosed with disconnected duct syndrome. The conservative management was continued for 3 more months. Pancreatic duct stenting was attempted but was not successful in cannulating the disconnected duct, and he was finally planned for a Roux-en-Y fistulojejnuostomy. The fistulojejunostomy was performed on an average of 6 months after placement of peri-pancreatic drain. The patient recovered uneventfully and is doing well at a 12-month follow-up. Refractory external pancreatic fistula is defined as an external pancreatic fistula not resolving with these measures for longer than 6 weeks. Most fistulas developing after acute pancreatitis are related directly to the need for necrosectomy to treat infected necrosis. Patients are initially approached conservatively. When patients fail to respond to either percutaneous drainage, endoscopic interventions, or novel techniques, operative intervention is the most viable approach to treat the fistula. Fistulojejunostomy is a safe and effective treatment for intractable pancreatic fistula having the benefit of avoiding a difficult major pancreatic resectional surgery, along with low postoperative morbidity and mortality. KEY WORDS: Acute pancreatitis, Pancreatic necrosis, Pancreatic fistula, Fistulojejunostomy.

Intracholecystic Papillary-Tubular Neoplasms (ICPN) of the Gallbladder.

Intracholecystic Papillary-Tubular Neoplasm (ICPN) is a rare tumor characterized by intraluminal papillary growth which may be associated with invasive carcinoma. In this study, we aimed to present the patient with the final pathologic diagnosis of end-stage ICPN presenting with the preliminary diagnosis of Gallbladder cancer. Key words: Cholecystectomy, Intracholecystic papillary neoplasm, Gallbladder cancer.

Importance of Multislice Computed Tomography in Determining the Severity of Chronic Liver Disease State.

BACKGROUND: In the present study, we aimed to put forward the relationship between multidetector computed tomography findings and scores for liver function evaluation. METHOD: Included in the study were 51 patients with liver cirrhosis. Preoperative creatinine levels, international normalized ratio and alpha-fetoprotein values, albumin and sodium levels, the presence of ascites and varices, Model for End-Stage Liver Disease (MELD) scores, MELD-Sodium (MELD-Na) scores, and Child-Turcotte-Pugh Classification, the presence of ascites and varices, the size of liver, the size and diameter of the spleen, portal vein diameter, splenic artery diameter, and proper hepatic and right hepatic artery diameter were all determined. RESULTS: Although the correlation between the spleen diameter and the MELD scores (P <.001) and MELD-Na scores (P = .02) was strong, there was no association with the Child-Turcotte-Pugh Classification (P = .08). Despite the correlations between portal vein diameter (P = .04) and splenic artery diameter (P = .04) and MELD scores, no association was detected with MELD-Na scores and the Child-Pugh scores. Even though a negative correlation between proper hepatic artery diameter (P = .18) and MELD-Na scores was noted, no statistically significant correlation could be identified with any scoring systems. In the multivariate linear regression analyses, the correlation between the portal vein diameter and MELD scores was significant as a radiologic finding. In the multiple linear regression analyses, the negative correlation between the right hepatic artery and MELD-Na scores diameter was statistically significant. In the multiple linear regression analyses, there was no statistically significant correlation between preoperative radiologic findings and Child-Turcotte-Pugh Classification. CONCLUSION: We believe that preoperative multislice computed tomography imaging in patients with chronic liver disease may contribute to the diagnosis of disease, the determination of vascular anomalies, and the grading of the severity of the disease.

Cyst of the canal of Nuck mimicking inguinal hernia.

INTRODUCTION: Coley, in 1892, reported 14 cases of a hydrocele in women. He described this "affection" as being "too rare an anomaly to deserve consideration. The rarity of this finding continues to be described in more current literature of 400 cases. CASE PRESENTATION: 42-year-old woman presented to the clinic with a palpable mass in her left inguinal region. On physical examination, a soft-consistency, mobile mass of about 4 cm in size was seen in the left inguinal region. The cystic lesion which was seen to be originated from the inguinal canal was excised in the exploration made by suspending the round ligament by passing through the anatomical folds with the incision made from the left inguinal region. The defect was repaired with prolene mesh after high ligation. Patient was discharged on the 1st postoperative day. DISCUSSION: In women, a round ligament is attached to the uterus close to the origin of the fallopian tubes, and the extension of the parietal peritoneum follows the round ligament as it passes to the inguinal canal through the internal ring. Hydroceles of the canal of Nuck were not conclusively diagnosed until surgery was performed on a suspected inguinal hernia. The treatment of Nuck canale hydroceles are surgery. Ligating the prosessus vaginalis and excision of the cyst in surgical treatment will prevent recurrences. CONCLUSIONS: Nuck canal cysts should be considered in the differential diagnosis of cases of female patient's complaints of swelling in the inguinal region.

A rare complication in a liver transplant patient: Meckel diverticulum perforation due to biliary stent.

INTRODUCTION: Meckel's diverticulum is the most common congenital lesion of the small intestine. The incidence varies between 0.5% and 2% Biliary stents can be used for the treatment of patients with bile duct complications. Intestinal perforation due migrated stents is a very rare and life threatening complication. "Perforation of the Meckel diverticulum due to stent", and no case was found in the literature. For this reason, our case has been identified as the first case seen in the literature. CASE PRESENTATION: A 20 year old male patient liver transplantation was performed from a live donor. 3 years ago The patient presented at our clinic with abdominal pain, nausea and vomiting that has been present for 2 days. Abdominal computed tomography showed a foreign body in the small intestines Patient was operated in emergency conditions. Meckel Diverticulum 40 cm proximal to the ileocecal valve and a biliary drainage catheter perforating the diverticule was seen Meckel's diverticulum was excised, primary repair was performed, Postoperative recovery was uneventful. DISCUSSION: Complication rates due to a biliary stent range between 8-10% with a mortality below 1% (Konstantinidis et al. [1]). The most feared complication due to a biliary stent is stent migration. The perforation rate due to stent migration is below 1%. It most commonly occurs in the duodenum. Patients with stent related perforations are surgically managed as other GIS perforations. CONCLUSIONS: Perforation due to stent migration should also be considered in differential diagnosis in patients with a biliary stent and Acute Abdomen.

18F-FDG activitiy PET/CT and CA-19.9 levels for the prediction of histopathological features and localization of peri- ampullary tumors.

BACKGROUND/AIMS: We sought to investigate the roles of maximum standardized uptake value (SUVmax) and serum carbohydrate antigen 19-9 (CA 19-9) in predicting the histopathological features of periampullary tumors. MATERIALS AND METHODS: Thirty-four patients with histologically confirmed periampullary tumors were classified into two groups, according to the localizations of their tumors (ampulla Vateri or pancreas). SUVmax was obtained from [(18)F]-fluorodeoxyglucose positron emission tomography computed tomography (18F-FDG PET/CT). SUVmax and CA 19-9 levels were measured and compared with histopathological features of the tumors. Logistic regression was used to assess the significance and independence of predictive factors. RESULTS: 18F-FDG PET/CT SUVmax (<2.5 vs. ≥2.5; p=0.031) and CA 19-9 level (normal vs. elevated; p=0.045) were significantly and independently predictive of the histopathological origin of the tumors (ampulla Vateri vs. pancreas). The ratio of CA 19-9 levels and SUVmax were found to be higher in cases of poorly differentiated tumors and tumors greater than 2 cm in diameter. CONCLUSION: A surgical approach to treatment may be considered for patients who have both i) an established or suspected diagnosis of periampullary tumors and ii) low SUVmax and CA 19-9 levels.

Comparison of Diverting Colostomy and Bowel Management Catheter Applications in Fournier Gangrene Cases Requiring Fecal Diversion.

In some patients of Fournier gangrene originated from perianal region, it is important to prevent fecal contamination in order to provide healing without wound infection. For this purposes, diverting colostomy or bowel management catheter methods were performed. In this study, it is aimed to carry out a comparison of prognosis and cost efficiency between diverting colostomy and bowel management catheter methods applied for preventing fecal contamination in Fournier's gangrene patients. Fourty-eight patients with diagnosis of Fournier's gangrene, serious perianal infections, and preserved sphincters and without rectum injury after debridement were included in the study. The cases were divided into two groups as patients who were subjected to colostomy for fecal diversion and who were subjected to bowel management catheter without colostomy. Then, the groups were compared in terms of age, predisposing factors, duration of hospital stay, mortality, additional surgery requirements, and cost. Fourty-eight patients were included the study. Sixteen patients were treated without colostomy. Decreased duration of total hospital stay, additional surgery requirements, and hospital expense in bowel management catheter group has determined. It is thought that preferring bowel management catheter method instead of colostomy in patients without rectum injury, who require diverting colostomy and have undamaged anal sphincters, can relieve patients, patients' relatives, healthcare organizations, and the national economy of a serious burden. In addition, although patients' satisfaction and workforce loss factors are not taken into consideration in this study, the bowel management catheter method is thought to have positive effects also on these parameters.

A case of uneventful ABO-incompatible liver transplantation from a deceased donor managed with routine immunosuppressive treatment.

ABO-incompatible liver transplantation (ILT) was formerly contraindicated because of the increased risk of antibody-mediated humoral graft rejection due to preformed anti-A/-B antibodies on recipient endothelial cells. A 2.5-year-old girl with end-stage liver disease underwent cadaveric donation ILT because of acute liver failure and esophageal variceal bleeding before transplantation. The patient's blood type was A Rh (-) and the donor's blood type B Rh (+). The operation and postoperative course were uneventful. The immunosuppression consisted of steroids, and tacrolimus was initiated on the day of the surgery. The patient's hemoglobin level did not change, and direct Coombs test performed daily was consistently negative. Anti-B titer was observed at a maximum of 1/8. The patient was followed up during the first year. This case of ILT from a cadaveric donor is significant because the 2.5-year-old recipient did not experience any complications after undergoing routine immunosuppressive treatment.

A rare cause of obstructive jaundice: Fasciola hepatica mimicking cholangiocarcinoma.

Fasciola hepatica is an endemic zoonotic disease in Turkey and neighboring countries. The usual definitive host is the sheep; humans are accidental hosts in the life cycle of the Fasciola. There are two disease stages: the hepatic (acute) and biliary (chronic) stages. When the flukes enter the bile ducts, the symptoms of cholestasis and cholangitis may present, which can easily be misdiagnosed as obstructive jaundice of other causes. We present a case of fascioliasis, which was difficult to differentiate from cholangiocarcinoma. A 47-year-old woman from Eastern Turkey presented with fever, right upper quadrant abdominal pain, and jaundice. Total bilirubin was 4.2 mg/dl, aspartate aminotransferase 55 IU/L, alanine aminotransferase 65 IU/L, alkaline phosphatase 325 IU/L, and gamma-glutamyl transpeptidase 172 IU/L. All tumor markers including carcinoembryonic antigen and Ca19-9 were in normal values. After extended evaluation, an explorative laparotomy with cholecystectomy, choledochostomy and T-tube drainage was performed. Multiple flukes were removed from the choledochus. One of the parasites was sent to the parasitological clinic for identification. The result of an indirect hemagglutination test for F. hepatica was 1/320 (+). In conclusion, the chronic phase of this zoonotic infection can be easily misdiagnosed as any other cause of obstructive jaundice. Thus, F. hepatica should be considered in the differential diagnosis of common bile duct obstruction, especially in endemic areas.