Obstructive sleep apnea: the effect of bariatric surgery after 12 months. A prospective multicenter trial.

BACKGROUND: Obstructive sleep apnea (OSA) is a highly prevalent sleep disorder, particularly in bariatric patients. It is known to be tightly linked with metabolic abnormalities and cardiovascular morbidity. Obesity is the most noteworthy individual risk factor for OSA. The aim of this study was to investigate the effect of a laparoscopic Roux-en-Y gastric bypass (LRYGB) on OSA one year after surgery. METHODS: In this prospective multicenter study standard overnight cardiorespiratory recording was conducted 12 months after bariatric surgery in 132 patients who had OSA in the baseline recording prior to the operation. The main outcome measures were changes in the prevalence of OSA and apnea-hypopnea index (AHI). In addition, the changes in anthropometric and demographic measurements including weight, body mass index (BMI), and waist and neck circumference were evaluated. A sleep symptom questionnaire was administered at baseline and at 12 months. RESULTS: The prevalence of OSA decreased from 71% at baseline to 44% at 12 months after surgery (p < 0.001). OSA was cured in 45% and cured or improved in 78% of the patients, but moderate or severe OSA still persisted in 20% of the patients after the operation. De novo OSA occurred in eight percent of the patients, and total AHI decreased from 27.8 events/h to 9.9 events/h (p < 0.001). CONCLUSIONS: LRYGB is effective in treating OSA. However, the findings demonstrate that a postoperative cardiorespiratory recording is needed in order to identify the patients with persistent moderate to severe OSA after the operation. CLINICAL TRIAL REGISTRATION: ClinalTrials.gov; No.: NCT01080404; URL: www.clinicaltrials.gov.

Prevalence of Obstructive Sleep Apnoea Among Patients Admitted for Bariatric Surgery. A Prospective Multicentre Trial.

BACKGROUND: Obesity has become one of the greatest public health concerns worldwide and is known to be the most important risk factor for obstructive sleep apnoea (OSA). Prevalence of OSA has increased over the last two decades, but it is estimated that the majority of cases still remain undiagnosed. The aim of this study was to investigate the prevalence of OSA in Finnish bariatric surgery candidates. METHODS: In this prospective multicentre study, standard overnight cardiorespiratory recording was conducted in 197 consecutive patients from three different hospitals. A sleep questionnaire was also administered. Anthropometric and demographic measurements included age, weight, body mass index (BMI) and waist and neck circumference. RESULTS: Altogether, 71 % of the patients were diagnosed with OSA. The prevalence was higher in males (90 %) than in females (60 %) (p < 0.001). In OSA patients' group, the mean neck and waist circumference was larger (p < 0.001) and the body weight higher (p < 0.01) than in non-OSA group. When separating patients by gender, a significant difference remained only concerning neck circumference in female patients. CONCLUSIONS: OSA is very common among bariatric surgery patients, especially in men. Considering this and the increased long-term morbidity and mortality generally related to OSA, a routine screening for OSA seems indicated in bariatric patients, particularly men.

Quality of life and sexual function 1 year after laparoscopic rectosigmoid resection for endometriosis.

AIM: Endometriosis is relatively common condition in fertile women and may affect the alimentary tract. Laparoscopic rectosigmoid resection for endometriosis has been found to be both feasible and safe. The aim of the present study was to prospectively evaluate the quality of life and sexual function of patients who have undergone rectosigmoid resection for endometriosis. METHOD: All patients undergoing rectal or sigmoid resection for endometriosis in two specialist hospitals were prospectively recruited in the study. Details regarding demography, endometriosis-related symptoms, procedure and postoperative recovery were collected. One year after the operation patients were sent a postal questionnaire asking about endometriosis-related symptoms, quality of life and sexual functioning. The 15D Questionnaire and McCoy Female Sexuality Questionnaire were used for this purpose. RESULTS: A total of 26 patients responded to the 15D questionnaire. Endometriosis-related bowel symptoms decreased significantly after the operation. The responses showed improvements in the overall score and scores for five different dimensions (usual activities, P = 0.04; discomfort and symptoms, P < 0.001; distress, P < 0.001; vitality, P < 0.001; sexual activity, P < 0.001). Sexual satisfaction was greater 1 year after the operation (P = 0.01). Sexual problems and partner satisfaction scores had not changed significantly. CONCLUSION: Laparoscopic rectal and sigmoid resection for endometriosis significantly reduce endometriosis-related symptoms and improve quality of life and sexual well-being.

The early outcome of laparoscopic sigmoid and rectal resection for endometriosis.

AIM: Deeply infiltrating endometriosis (DIE) is the most severe form of endometriosis and may affect the rectum and sigmoid colon. The most effective treatment is segmental resection. We report our results of rectal and sigmoid resection for this. METHOD: The study comprises all patients who have had laparoscopic bowel resection for rectal or sigmoid endometriosis in the Päijät-Häme Central Hospital between 1 January 2004 and 31 May 2007. Patient demographics, operative details, complications and early postoperative recovery were prospectively collected and analysed. RESULTS: A total of 31 patients were treated using a multidisciplinary approach. The mean age was 33.6 years (range 21.7-48.6) and body mass index 24.2 (17-40). The mean operation time was 253.5 min (range 56-484). There were three sigmoid and 28 rectal resections and 80 concomitant gynaecological procedures. Conversion to open surgery was not required. A total of 23 (74.2%) patients recovered without complications. There were two major complications, anastomotic leakage and rectovaginal fistula. Minor complications included transient urinary retention (2), wound infection (1), pneumonia (1) and undefined fever (2). The mean time to full peroral diet was 3.8 days (range 3-7), to first flatus 2.6 days (1-4), to first bowel movement 3.5 days (2-6) and to discharge 5.7 days (4-13). CONCLUSION: Laparoscopic rectal and sigmoid resection for deep intestinal endometriosis is safe with few severe complications and rapid recovery. The long-term outcome on symptoms requires further study.

Virtual reality laparoscopic simulator as an aid in surgical resident education: two years' experience.

BACKGROUND AND AIMS: Virtual reality (VR) laparoscopic simulator training has been shown to augment the learning of skills needed in real laparoscopic operations. We report here our two-year experience of using a VR simulator in the training of surgical residents. METHODS: A VR laparoscopic simulator was purchased for Päijät-Häme Central Hospital at the end of November 2005. From 1 December 2005 onwards surgical residents in our hospital were encouraged to voluntarily practise with the VR simulator. After the VR simulator had been in use for two years all the data stored in the simulator's computer memory was collected and analysed. RESULTS: In this two-year period a total of 79 persons practised with the simulator. The total number of performed tasks stored in the computer was 2,090. The training activity varied greatly between residents (6-171 tasks). The performance in simulator tasks differentiated between residents and GI surgeons. The learning curve of the residents in basic tasks was steep but their performance failed to reach the level of experienced laparoscopic surgeons in most tasks. CONCLUSIONS: The VR simulator was well used. Practising with a VR simulator on a voluntary basis can result in inadequate training. The VR laparoscopic simulator differentiates between subjects with different laparoscopic skills and shows good construct validity.

Undetected coeliac disease in the elderly: a biopsy-proven population-based study.

BACKGROUND: Up to 1% of the population suffer from coeliac disease. Data on the prevalence in elderly people is scant. We hypothesized that they would over time have developed obvious symptoms. Clinically silent or undiagnosed disease would thus be relatively uncommon. AIMS: To evaluate the prevalence of coeliac disease in elderly people. METHODS: The study comprised 2815 individuals aged 52-74 years. Clinical cases of coeliac disease were recorded. Sera from all subjects were screened by IgA class tissue transglutaminase antibodies, and seropositive underwent small bowel biopsy. RESULTS: Coeliac disease was detected in altogether 60 individuals, in 25 (0.89%) on clinical grounds, and screening found in 35 (1.24%) new biopsy-proven cases. Thus, a total prevalence of 2.13% (95% confidence intervals 1.60-2.67%) was reached. Of the screen-detected cases, 15 had symptoms, albeit mostly mild. Two out of the 60 had small bowel T-cell lymphoma and two had gastric cancer. The total frequency of biopsy-proven coeliac disease and seropositive cases without histological confirmation was 2.45% (1.88-3.02%). CONCLUSION: The prevalence of coeliac disease in elderly people was higher than what has been reported in the population in general. Active case finding by serologic screening is encouraged, since undetected cases may be prone to increased morbidity and mortality.

The cleansing result of oral sodium phosphate is inversely correlated with time between the last administration and colonoscopy.

BACKGROUND: There is some evidence that the timing of sodium phosphate (NaP) ingestion affects the cleansing result. The objective of this study was to evaluate the correlation of cleansing result with the timing of ingestion of NaP. METHODS: 214 consecutive outpatients scheduled to undergo colonoscopy were enrolled in the study. All patients filled out a detailed questionnaire concerning the execution of bowel cleansing. Concomitant with colonoscopy, patient characteristics were recorded and after the procedure the cleansing result was scored. The correlation between cleansing score and time from the last dose of NaP to colonoscopy was evaluated. For further analysis, patients were divided into three groups regarding the time lag from NaP taking to colonoscopy (group 1, 6 h or less; group 2, 6-12 h; group 3, 12 h or more). RESULTS: 204 patients had complete colonoscopy and enough data to be analyzed for the study. The Pearson correlation coefficient for the time between the last dose of NaP and colonoscopy was -0.450 (p=0.0001) showing an inverse correlation. The mean cleansing score (+/-SEM) of group 1 was 4.00+/-0.12, for group 2 it was 3.56+/-0.12, and for group 3 it was 2.64+/-0.14. There were statistically significant differences between all groups. CONCLUSION: The cleansing result of NaP is inversely correlated with the time between last dose of NaP and colonoscopy. Colonoscopy should be preferably performed within 12 hours of taking the second dose of NaP.

Neuromuscular and sensory disturbances in patients with well treated coeliac disease.

OBJECTIVES: A body of evidence shows that coeliac disease is associated with protean manifestations outside the intestine, and neurological disorders are well recognised. However, it remains obscure whether there are signs of clinical or subclinical nervous system involvement even in patients adopting an adequate gluten free diet. The aim of this study was to assess in a controlled study whether patients with treated coeliac disease carry an increased risk for neuropathy and characterise the type of possible neuropathy. METHODS: Electroneuromyographic findings and vibration, thermal, and tactile thresholds of 26 patients with coeliac disease and 23 patients with reflux disease were analysed. RESULTS: Six (23.1 %) coeliac disease patients and one (4.3 %) reflux disease patient showed findings of chronic axonal neuropathy in quantitative needle EMG. In addition, two coeliac disease patients showed findings suggestive for myopathy. There were no significant differences in warm, cold, or vibration thresholds between the groups but means of heat pain thresholds and tactile thresholds were significantly higher in coeliac patients than in controls. CONCLUSION: An increased occurrence of axonal neuropathy was observed in well treated coeliac disease. This further indicates that neurological manifestations occur even in patients without overt malabsorption.

Inoperable adenocarcinoma of the oesophagogastric junction: a comparative clinical study of laser coagulation versus self-expanding metallic stents with special reference to cost analysis.

AIMS: Neither clinical nor financial comparisons yet exist between self-expanding metallic stents (SEMS) and laser therapy, concentrating on the treatment of obstructive adenocarcinomas of the oesophagogastric junction. The aim of our study was to compare the relative lifetime costs and clinical results of the Nd:YAG laser to those of SEMS as alternative forms of primary palliation of dysphagia for adenocarcinoma near the oesophagogastric junction. METHODS: Fifty-two patients with distal oesophageal or oesophagogastric adenocarcinomas underwent palliative treatment for dysphagia: 32 treated with laser therapy and 20 with SEMS in this retrospective study. The clinical outcome and real cumulative costs as physical units and in financial terms were analysed for these study groups. RESULTS: Although patients palliated with SEMS underwent fewer procedures (1.9+/-1.6 vs 3.4+/-4.0, P=0.0048) and spent less time in endoscopic theatre (38+/-25min vs 118+/-152min, P=0.0048), they spent as many days in hospital (12.9 vs 15.1, P=0.370) and required as high overall costs for therapy (5360 EUR vs 5450 EUR, P=0.679) as those treated with laser therapy. In addition, they had higher morbidity rates (30 vs 6.3%, P=0.043), hospital mortality (20 vs 3.1%, P=0.066), and 30-day mortality (40 vs 3.1%, P=0.0011) than did patients with laser therapy, with no evidence of SEMS being the more effective treatment modality. CONCLUSIONS: In patients with adenocarcinoma at the distal oesophagus or at the oesophagogastric junction, laser therapy palliates dysphagia effectively with lower morbidity and mortality rates and without increased costs or hospital stays than does use of self-expanding metallic stents.

Dysphagia and oesophageal clearance after laparoscopic versus open Nissen fundoplication. A randomized, prospective trial.

BACKGROUND: An increase in postoperative dysphagia has been reported after laparoscopic fundoplication. Our aim was to compare laparoscopic Nissen-Rossetti fundoplication to open fundoplication regarding oesophageal clearance and dysphagia in a prospective, randomized study. METHODS: Twenty-eight consecutive patients with objectively observed gastro-oesophageal reflux disease referred to operative treatment were randomized to laparoscopic (13) or open (15) fundoplication. A standard formula was used in pre- and postoperative interview. Oesophageal clearance was measured by liquid bolus radionuclide transit before and 3 days, 1 month and 1 year after fundoplication. Endoscopy was done preoperatively and 1 year after the operation. RESULTS: Heartburn, regurgitation and ooesophagitis were cured with equal effectiveness (p = 0.001). New-onset dysphagia was observed in nine (69%) of the patients in the laparoscopic group and in nine (60%) in the open group during the first postoperative month. Food impaction occurred in four (31%) cases after laparoscopic and in two (13%) after open surgery (ns). One year after the operation, one patient (8%) in both groups had more than mild symptoms. Oesophageal radionuclide transit remained normal after open fundoplication, but after the laparoscopic procedure oesophageal clearance was disturbed--only one patient did not have a pathologic result during the first postoperative month. One year after the operation, clearance was normal. CONCLUSIONS: After laparoscopic operation, a tendency to more severe new-onset dysphagia was observed, and oesophageal clearance was transiently disturbed. Efforts should be made to minimize postoperative swallowing and clearance disturbances after laparoscopic fundoplication in order to get the full value out of otherwise more rapid recovery.

Partial aminomethylation of resorcarenes.

Aminomethylation of resorcarenes at the wider rim with bulky diisopropylamine and formaline leads to trisubstituted derivatives. Analogous reaction with C(2v)-symmetrical resorcarene tetratosylate gives the monoaminomethylated compound. Further reactions of remaining unsubstituted resorcinol rings result in new resorcarene derivatives. [reaction: see text]

The long term results of open antireflux surgery in a community-based health care center.

OBJECTIVE: There is no previous study concerning long term results of open Nissen fundoplication performed by general surgeons in a nonspecialized unit. METHODS: Of 45 consecutive patients in a general provincial center, 39 were available for follow-up after a mean period of 78 months. All patients were interviewed using a standard questionnaire, and 35 of them consented to undergo endoscopy. RESULTS: Of the patients, 85% had no or only mild reflux symptoms. The figures for dysphagia, flatulence, and bloating were 31%, 67%, and 46%, respectively. Endoscopy showed defective fundic wrap in 37% of the patients and erosive esophagitis in 29%. Five patients (13%) with recurrent esophagitis were referred for H2-blocker or omeprazole medication, and five others (13%) were scheduled for repeat antireflux surgery. CONCLUSIONS: The results were somewhat worse in regard to prevalence of defective fundic wrap and recurrent esophagitis than in other reports, which were from specialized units.

Randomized trial to study the effect of fundic mobilization on long-term results of Nissen fundoplication.

BACKGROUND: It has been suggested that fundic mobilization in Nissen fundoplication decreases adverse postoperative symptoms and increases the durability of the fundic wrap. There are no previous randomized, prospection long-term studies assessing this. This study addresses the question. METHODS: Fifty consecutive patients were randomized to undergo open Nissen-Rossetti fundoplication with total fundic mobilization (n == 26) or an identical procedure without mobilization (n == 24). After a median of 36 (range 6-53) months 49 had endoscopy and a personal interview. RESULTS: Oesophagitis was cured in 20 of 21 patients who had fundic mobilization and 18 of 19 who did not. a defective fundic wrap was observed in five and recurrent reflux symptoms in six of those who had fundic mobilization compared with two and one respectively of those who did not (P not significant). Recurrent sliding hiatal hernia was observed in nine of those with a mobilized fundus and one of those without (P == 0.02). There was no significant difference in incidence of new-onset long-term dysphagia, subjective belching ability, amount of flatus or bloating between the study groups. CONCLUSION: Fundic mobilization did not give any apparent advantage regarding postoperative adverse effects. Instead, it was associated with a higher rate of recurrent hiatal hernia.

Surgical experience improves the long-term results of Nissen fundoplication.

BACKGROUND: Nissen fundoplication relieves symptoms of gastro-oesophageal reflux and effectively heals oesophagitis. During long-term follow-up some cases of recurrent reflux are seen. We investigated the possibility that long-term cure of gastro-oesophageal reflux after fundoplication is influenced by the surgeon's experience and focused interest, in line with results of surgery for rectal, gastric, and breast cancer. METHODS: One hundred and five consecutive patients were evaluated a median of 77 months after open Nissen-Rossetti fundoplication for erosive oesophagitis. Follow-up included personal interviews and upper gastrointestinal endoscopy by an investigator not previously involved in the patients' treatment. The surgeons were classified as experienced (>10 of the operations in the series), less experienced (<10 operations), or trainees. RESULTS: Of the most experienced surgeons' patients, 97% had no or at most mild reflux symptoms at follow-up, compared with 88% of the of less experienced surgeons' patients (P = 0.04). Healing of erosive oesophagitis was commoner when the operations were performed by experienced specialist surgeons (88% versus 72%; P = 0.04). The reoperation rate fell as the surgeons' experience increased, from 12% to 4%. CONCLUSIONS: Surgery for gastro-oesophageal reflux should be centralized to units specializing in the techniques and with sufficient annual numbers of operations to optimize results. This policy becomes especially advisable as laparoscopic surgery increases the numbers of treated patients.

Antireflux surgery enhances gastric emptying.

OBJECTIVE: To evaluate the influence of antireflux surgery on gastric emptying. DESIGN: Nonrandomized controlled trial 3 months before and after surgical intervention. SETTING: Secondary and tertiary referral center. PATIENTS AND CONTROL SUBJECTS: Twenty consecutive patients (7 women, 13 men), mean age 49.2 years, with symptomatic, objectively confirmed gastroesophageal reflux disease and 10 healthy control subjects (3 women, 7 men), mean age 37.3 years. INTERVENTION: Laparoscopic or open Nissen fundoplication (in 1 case Toupet 180 degrees posterior hemifundoplication). MAIN OUTCOME MEASURES: Gastric emptying scintigraphy, using solid food, in control subjects and patients 3 months before and 3 months after the operation; time to halving of the maximal activity and the activity remaining at 60, 100, and 120 minutes. RESULTS: Preoperative symptoms included pyrosis in 19 of 20 patients and regurgitation in 18. Three months postoperatively, 19 patients were symptom-free. The mean time to halving of the maximal activity decreased from 113 to 78 minutes (P = .001). Delayed gastric emptying was found postoperatively in 3 patients, compared with preoperative values, using activity at 60, 100, 120 minutes and the mean time to halving of the maximal activity as the variables. Compared with control subjects, gastric emptying was slower in patients preoperatively and faster postoperatively, but the difference was not statistically significant. CONCLUSION: Gastric emptying is enhanced after antireflux surgery, along with cessation of symptoms and healing of esophagitis.

Late results of paraoesophageal hiatus hernia repair with fundoplication.

BACKGROUND: Most published reports on results of surgical treatment for paraoesophageal hiatus hernia have been based on patient questionnaires, and seldom included endoscopy or barium meal examinations. METHODS: Eight pure and 14 mixed-type paraoesophageal hernias were evaluated a median of 37 (range 2-241) months after surgical repair. An antireflux procedure was done in 19 cases. Before operation all had endoscopy or barium meal (20 and 19 patients respectively); after operation 19 had endoscopy and 12 also had barium meal examination. Oesophageal 24 h pH monitoring was done in five cases before surgery, and in 11 afterwards. RESULTS: Preoperative symptoms of reflux were reported by 18, and were often accompanied by dysphagia, postprandial vomiting or epigastric pain. Symptoms improved after operation, and 21 of the 22 patients were satisfied with the result. At follow-up examination, a recurrent hernia was found in eight of the 19 patients examined. Four of these hernias were sliding, two were mixed type and two purely paraoesophageal. DISCUSSION: Recurrence of symptoms was associated with persistence of reflux rather than hernia recurrence. Concomitant antireflux procedure is recommended in all operations for mixed-type hiatus hernia, but it should also be considered for purely paraoesophageal hernia if reflux cannot be excluded before operation, or if retro-oesophageal dissection is needed.

Histological improvement of oesophagitis after Nissen fundoplication.

Nissen fundoplication gives lasting relief from symptoms of gastro-oesophageal reflux and cures endoscopic oesophagitis effectively. The histological effect on the oesophageal mucosa is less clear. We studied the long-term histological effect of Nissen fundoplication on refractory gastro-oesophageal disease with erosive oesophagitis or Barrett's metaplasia in 33 patients with biopsy both before and after antireflux surgery. The median postoperative interval to re-examination was 80 (range 37-110) months. Symptoms of reflux were greatly relieved; 31 (94%) of the 33 patients had none or, at the most, mild symptoms. Endoscopic oesophagitis was healed in 26 (79%) of the cases. The histological appearance of the oesophageal mucosa had been abnormal in all the patients preoperatively, but at follow-up it was normal in 22 cases (67%): in 89% of the patients without objectively observed recurrent reflux and in 45% of those with recurrence. Both the pre- and postoperative severity of the histological changes correlated significantly with the endoscopic grade of oesophagitis (r=0.42, P=0.017 and r=0.837, P=0.0001, respectively), but not with the clinical reflux score. In conclusion, Nissen fundoplication resulted in histological healing in the great majority of patients with oesophagitis.

Enteral or parenteral feeding after total gastrectomy: prospective randomised pilot study.

OBJECTIVE: To compare the efficacy and cost of enteral and parenteral feeding after total gastrectomy. DESIGN: Prospective randomised open study. SETTING: University hospital, Finland. SUBJECTS: 29 patients undergoing curative total gastrectomy for gastric cancer. INTERVENTIONS: 13 patients were given early enteral feeding by nasojejunal tube and 16 patients parenteral nutrition by central venous catheter. MAIN OUTCOME MEASURES: Postoperative complications, duration of hospital stay, serum CRP and albumin concentrations, cost, and postoperative abdominal symptoms. RESULTS: One patient in the enteral feeding group discontinued the study on day 1. Oesophagojejunal leaks developed in one patient in each group. Infective complications occurred in 3 (23%) in the enteral group and 5 (31%) in the parenteral group. Serum CRP concentration on day six was lower in the enteral feeding group than in the parenteral feeding group (32 (16) g/L compared with 61 (41) g/L; p = 0.02). Enteral feeding was well tolerated. Diarrhoea developed earlier in the enteral than in the parenteral group (days 3-5 compared with 5-7, respectively) but there was a tendency to an increased risk of diarrhoea in the parenteral group. Parenteral feeding was more than four times as expensive as enteral feeding. CONCLUSION: Enteral nasojejunal feeding is safe and well tolerated after total gastrectomy. It is also cheaper than parenteral nutrition.

Complications of open and laparoscopic antireflux surgery: 32-year audit at a teaching hospital.

BACKGROUND: Open or laparoscopic surgery for gastroesophageal reflux disease gives longterm freedom from symptoms in 83-100% of cases but has a certain percentage of complications. This study was undertaken to evaluate the early and late complication rates after primary or repeat antireflux operations. STUDY DESIGN: The records of all patients who underwent surgery for gastroesophageal reflux disease during a 32-year period at a university teaching hospital were reviewed retrospectively. Records for 793 adults (448 men and 345 women) aged 16-85 years (mean, 51) were retrieved for calculation of complication rates and statistical analysis. RESULTS: A total of 827 operations were performed: 793 primary and 41 for recurrent disease (2 patients were each reoperated on twice). There were 49 laparoscopic operations. Only two patients died (mortality, 0.3%), both after open operation. Morbidity was 24% after open surgery and 14% after laparoscopic operation. The total (early and late) complication rate was higher after reoperations than that after open or laparoscopic procedures. The overall complication rate in the open operations was similar in the first and the third decade of the study, namely, 24.6% and 26.1%, respectively. CONCLUSIONS: Surgical treatment of gastroesophageal reflux disease carries very low mortality when performed in a specialized unit. The main causes of morbidity after open operation are infectious complications. The incidence of complications is substantially lower after laparoscopic surgery than after open operation. Reoperation is seldom required, but it carries higher morbidity than the primary operations.