The Effect of Teaching Via Telecommunications: A Comparison of the Academic Performance of RN-BSN Students in Satellite Centers and On Campus

The overall success of the delivery of courses in the nursing major via telecommunication requires careful planning and coordination among the on-campus course faculty, satellite area faculty facilitators, the personnel responsible for the technology, and contact persons in satellite areas responsible for classroom scheduling. Maintaining satellite programs for RN students is a project that requires ongoing evaluation.

Impairment of pulmonary macrophage function with total parenteral nutrition

OBJECTIVE

The effects of total parenteral nutrition (TPN) administration on pulmonary macrophage function and host response to gram-negative pulmonary infection were evaluated.

SUMMARY BACKGROUND DATA

Administration of TPN resulted in increased infectious complications in traumatized and perioperative patients, but underlying mechanisms are unclear.

METHODS

Twenty-six male Wistar rats underwent central vein cannulation and were randomized to isocaloric feeding of a regular chow diet (RD) plus saline infusion or TPN without chow diet for 7 days. Pulmonary alveolar macrophage (PAM phi) superoxide production, Candida albicans phagocytosis and killing, and tumor necrosis factor (TNF) production in response to endotoxin (LPS) were assessed. Mesenteric lymph nodes (MLN) were cultured. A second group of rats (n = 6/group) were inoculated intratracheally with a sublethal dose of 9 x 10(9) live Escherichia coli per animal, and the lungs were cultured quantitatively 72 hours later to assess bacterial clearance. Finally, 11 RD-fed rats and 13 TPN-fed rats received intratracheal inoculation of 1.4 x 10(10) live E. coli and were included in follow-up.

RESULTS

Administration of TPN was associated with a significant increase in bacteria positive MLN compared with those in the RD group (p < 0.01). Pulmonary alveolar macrophage superoxide production, Candida albicans phagocytosis and killing, TNF production, and pulmonary clearance of bacteria were decreased significantly in TPN-fed rats compared with those fed a regular chow diet (p < 0.05). These pulmonary macrophage function changes were associated with a significantly higher mortality in TPN-fed rats compared with RD-fed rats after higher dose pulmonary E. coli inoculation.

CONCLUSIONS

Defective host pulmonary antimicrobial immune responses during TPN are associated with intestinal bacterial translocation, and may explain increased infectious complications.

Inhibition of nitric oxide synthesis is detrimental during endotoxemia

BACKGROUND

Increased production of nitric oxide has been implicated as a mediator during septic shock and sepsis syndrome. Inhibition of nitric oxide production could be beneficial during endotoxemia to improve the individual's hemodynamic status and possibly outcome.

OBJECTIVE

To evaluate the effects of nitric oxide inhibition on macrophage function and survival in a murine sepsis model.

DESIGN

Sixty-eight female Swiss-Webster (ND4) mice were injected with a sublethal dose of Escherichia coli lipopolysaccharide (25 mg/kg).

INTERVENTION

The treated group (n = 34) received 10 mg/kg of NG-nitro-L-arginine methyl ester at the time of lipopolysaccharide injection.

MAIN OUTCOME MEASURES

Blood samples and peritoneal macrophages were obtained at baseline and at 2, 4, and 8 hours after injection. Nitrite levels were measured in 36 mice from plasma and supernatant samples of cultured peritoneal macrophages stimulated with interferon gamma (100 micrograms/mL) for 48 hours. Thirty-two animals were observed for survival.

RESULTS

Administration of N-nitro-L-arginine methyl ester after lipopolysaccharide injection caused significant reductions in macrophage mean nitrite production from 13 and 15 mumol/L to 7 and 11 mumol/L (P < .05) and reduced mean plasma nitrite concentrations from 100 and 118 mumol/L to 46 and 108 mumol/L (P < .05) at 2 and 4 hours, respectively. The rate of survival was significantly decreased to 0% in the group receiving N-nitro-L-arginine methyl ester after septic challenge compared with 87.5% in controls (P < .005).

CONCLUSIONS

Inhibition of nitric oxide production is detrimental in this murine model of endotoxemia.

Total parenteral nutrition, bacterial translocation, and host immune function

Total parenteral nutrition (TPN) is associated with increased infectious complications in trauma and perioperative patients compared with enteral nutrition support. This study evaluated the effects of TPN on splenocyte and peritoneal macrophage (PM phi) function and intestinal bacterial translocation. Male Wistar rats underwent central vein cannulation and were randomized to isocaloric feeding of a regular chow diet (RD) plus saline infusion or TPN for 7 days. Splenocytes and PM phi were harvested to assess concanavalin A mitogenesis, superoxide production, and Candida albicans phagocytosis. Bacteria-positive mesenteric lymph nodes (MLNs) were found in 77% (10 of 13) of TPN-fed rats compared with 17% (2 of 12) of RD-fed rats (p < 0.05). Splenocyte mitogenesis, PM phi superoxide production, and C. albicans phagocytosis were significantly decreased in the TPN group compared with results in the RD group. In a second study, rats received RD, TPN, and parenteral nutrition (PN) with 10% or 20% of calories given as oral chow (PN and 10% chow and PN and 20% chow) for 7 days. PN and 10% chow reversed the TPN-induced suppression of C. albicans phagocytosis. PN + 20% chow significantly increased splenocyte mitogenesis, PM phi superoxide production, and C. albicans phagocytosis and killing to normal levels and was associated with a decreased incidence of bacteria-positive MLN. Thus, administration of TPN is associated with impaired PM phi microbicidal and splenocyte proliferative function. These defective cellular functions were reversed with a small amount of oral feeding.

The effect of dietary protein depletion on hepatic 5-fluorouracil metabolism

BACKGROUND

Protein calorie malnutrition, which is highly prevalent in tumor-bearing hosts, increases toxicity to 5-fluorouracil (5-FU), but the mechanisms are unclear. This study investigated the effects of protein depletion on 5-FU in vivo hepatic metabolism using F19-nuclear magnetic resonance spectroscopy (19F-NMRS).

METHODS

Rats received normal (21.5%) or low (2.5%) protein diet for 25 days. 5-FU was injected intraperitoneally, and hepatic fluorine spectra were obtained. Parallel experiments were conducted to determine serum 5-FU pharmacokinetics using high-performance liquid chromatography (HPLC) and to measure hepatic dihydropyrimidine dehydrogenase (DPD) activity.

RESULTS

The mean time of initial detection of fluoro-beta-alanine and the mean duration of the 5-FU signal in the liver were significantly prolonged in the low-protein group. 5-FU clearance and hepatic DPD activity were significantly lower in the low-protein group. Low-protein animals demonstrated increased toxicity, with diarrhea, weight loss, leukopenia (P < 0.001), and an 85% mortality, compared with regular diet animals, who had mild diarrhea and weight loss but no leukopenia and a 12% mortality.

CONCLUSION

Protein depletion results in increased toxicity to 5-FU, which is associated with a significantly decreased rate of hepatic metabolism and clearance of 5-FU and a significant decrease in hepatic DPD activity. 19F-NMRS can noninvasively identify these alterations of 5-FU metabolism in vivo and may serve as a useful guide to determining chemotherapy dosage adjustments to reduce toxicity.

Enteroenteric intussusception due to a metastatic malignant fibrous histiocytoma

Intussusception secondary to metastatic sarcoma is an unusual cause of small bowel obstruction. When a patient who has no history of a previous laparotomy, and has a known malignancy which metastasized hematogenously, presents with small bowel obstruction, the diagnosis of intussusception should be considered. The patient should be evaluated and treated accordingly.

Diagnosis and management of distant recurrence in soft-tissue sarcomas

Understanding of the patterns of, and treatments for, metastatic disease from soft-tissue sarcoma is of vital importance in caring for these patients. Metastasis can occur independently of adequate local control. When metastasis occurs, it usually causes no symptoms. Thus, all patients with malignant soft-tissue sarcomas must be followed with a careful surveillance regimen. When metastasis is discovered, the overriding goals of surgical treatment must be total resection of all tumor with the minimal loss of functional lung tissue. Multiple subsequent resections may be needed for recurrent metastasis but the goals remain the same. Postoperative chemotherapy may be of benefit in eradicating residual micrometastases. With ongoing research and the advent of more effective and better-tolerated adjuvant therapies, we should continue to make progress obtaining better cure rates and longer duration of survival for these patients.

Role of bactericidal permeability-increasing protein in the treatment of gram-negative pneumonia

BACKGROUND

Gram-negative infections are a major cause of morbidity and death. Bactericidal permeability-increasing protein (BPI) is an endotoxin-neutralizing protein that also exhibits potent bactericidal activity. This study compared the efficacy of a 23 kd recombinant N-terminal fragment of BPI (rBPI23) with that of antiendotoxin antibody E5 in a model of gram-negative sepsis.

METHODS

Sixty Swiss-Webster mice (Carworth farm) received an intratracheal inoculation of Escherichia coli (7 x 10(6) colony-forming units) and were randomized to three groups (20 per group). Starting immediately after inoculation, the groups received either rBPI23 (4 mg/kg intravenously every 2 hours for four doses), E5 (11 mg/kg intravenously every 24 hours for two doses), or an isotype control antibody B55 (11 mg/kg intravenously every 24 hours for two doses) and were followed up for survival. In a second survival study, 40 mice received the same intratracheal inoculation of E. coli and were randomized to two groups. Starting 2 hours after inoculation, the groups received either rBPI23 (4 mg/kg intravenously every 2 hours for four doses) or E5 (8 mg/kg intravenously every 12 hours for four doses) and were followed up for survival. In a third study, mice received an intratracheal inoculation of 3 x 10(6) colony-forming units E. coli, a sublethal dose, and were killed to determine pulmonary and blood clearance of bacteria.

RESULTS

rBPI23 conferred significantly greater protection from death than either E5 or B55 when started immediately (95% survival vs 20% and 10%, respectively; p < 0.001) or 2 hours after inoculation (65% survival vs 25% for E5; p < 0.05). Both pulmonary and vascular clearance of bacteria was enhanced significantly by treatment with rBPI23.

CONCLUSIONS

rBPI23 may be a novel therapeutic agent in the management of gram-negative sepsis.

Macrophage-dependent candidacidal mechanisms in the murine system. Comparison of murine Kupffer cell and peritoneal macrophage candidacidal mechanisms

Candida albicans infection is common in immunocompromised patients. The role of fixed tissue macrophages (M phi), including Kupffer cells (KC) and peritoneal macrophages (PM phi), in host defense against C. albicans is unclear. This study examined murine M phi candidacidal mechanisms and evaluated the in vitro role of the macrophage-activating factor IFN-gamma in augmenting these mechanisms. The effect of in vivo administration of IFN-gamma on survival after lethal C. albicans challenge in the murine system was also assessed. Percent PM phi and KC ingestion of C. albicans were similar. Prior opsonization of Candida increased the percentage of M phi ingestion of this pathogen. PM phi and KC phagocytic function was similar for both nonopsonized and opsonized C. albicans, but KC demonstrated markedly decreased ability to kill this pathogen (O2-, Candida killing). IFN-gamma enhanced KC and PM phi candidacidal activity. PM phi and KC Ag presentation was increased in early Candida infection, but diminished in established infection, when the majority of animals died. C. albicans failed to elicit significant amounts of either IL-1 or TNF compared with LPS stimulation of PM phi and KC in vitro. IFN-gamma treatment in vivo was associated with significantly improved survival (p &lt; 0.01).

Macrophage-dependent candidacidal mechanisms in the murine system. Comparison of murine Kupffer cell and peritoneal macrophage candidacidal mechanisms

Candida albicans infection is common in immunocompromised patients. The role of fixed tissue macrophages (M phi), including Kupffer cells (KC) and peritoneal macrophages (PM phi), in host defense against C. albicans is unclear. This study examined murine M phi candidacidal mechanisms and evaluated the in vitro role of the macrophage-activating factor IFN-gamma in augmenting these mechanisms. The effect of in vivo administration of IFN-gamma on survival after lethal C. albicans challenge in the murine system was also assessed. Percent PM phi and KC ingestion of C. albicans were similar. Prior opsonization of Candida increased the percentage of M phi ingestion of this pathogen. PM phi and KC phagocytic function was similar for both nonopsonized and opsonized C. albicans, but KC demonstrated markedly decreased ability to kill this pathogen (O2-, Candida killing). IFN-gamma enhanced KC and PM phi candidacidal activity. PM phi and KC Ag presentation was increased in early Candida infection, but diminished in established infection, when the majority of animals died. C. albicans failed to elicit significant amounts of either IL-1 or TNF compared with LPS stimulation of PM phi and KC in vitro. IFN-gamma treatment in vivo was associated with significantly improved survival (p < 0.01).

Genetic and antigenic analysis of an equine influenza H 3 isolate from the 1989 epidemic

The haemagglutinin (HA) gene from the equine influenza H3N8 isolate Suffolk/89 has been cloned by reverse transcription and polymerase chain reaction amplification. The nucleotide sequence of the HA gene was determined from two independently cloned copies of the gene and was found to be most closely related to recent American isolates supporting the idea that most isolates of equine H3N8 are evolving as a single lineage. When the predicted amino acid sequence of the Suffolk/89 HA was examined, changes had taken place in at least four of the major antigenic sites, A, B, C, and D when compared to the sequences of the isolates used in the current vaccines (Miami/63 and Fontainebleau/79). Surprisingly, when the Suffolk/89 isolate was tested in haemagglutination inhibition (HI) assays with a panel of six mouse monoclonal antibodies, no differences were observed between the Suffolk/89 and the Fontainebleau/79 isolates, suggesting that this panel of monoclonal antibodies may recognise a limited subset of the major antigenic sites. Three anti-HA horse heterohybridoma monoclonals were able to distinguish between the Suffolk/89 and Fontainebleau/79 viruses, demonstrating that the horse does recognise these isolates as being antigenically different. The results of the work suggest that the isolates used in current equine influenza vaccines may need updating.

Perioperative care of the oncology patient

Cancer patients are often at high risk for perioperative complications because of preexisting conditions, the magnitude of surgery, and the use of aggressive multimodality treatment. It is essential to identify risk factors preoperatively, correct any deficits, and monitor organ dysfunction. During the perioperative period prophylaxis and surveillance for cardiopulmonary, hematologic, and septic complications should minimize morbidity and mortality. Finally, nutritional support should be given to malnourished patients undergoing extensive operative procedures.

Malnutrition, injury, and the host immune response: nutrient substitution

Improvements in surgical management and intensive care therapy have enabled many patients to initially survive severe life-threatening trauma or major surgical procedures only to die after delayed bouts of sepsis. This paper reviews literature published within the past year on the effects of nutrient substitution on malnutrition, injury, and the host immune response. Topics discussed include immunodeficiencies in trauma and malnutrition, immunomodulation by nutrition, and parenteral versus enteral nutrition. We also discuss the roles of arginine, glutamine, omega-3 fatty acids, and dietary nucleotides in the host immune response.

Use of radiolabelled monoclonal antibodies in patients with primary and metastatic large bowel cancer

Accurate assessment of the extent of primary and metastatic large bowel cancer is critical to surgical decision making and to providing reliable prognostic information. This prospective study compared external gamma camera images and an intraoperative hand-held gamma detecting probe for detection of radiolabelled monoclonal antibody (B72.3) in 28 patients with primary and metastatic large bowel cancer. Fourteen patients received 0.2 to 20 mg (2 or 5 mCi) 111indium-labelled monoclonal antibody B72.3 followed by whole body imaging scan with an external gamma detector/camera on two occasions 24 h apart within 7 days after injection. Fourteen patients received 1.0 mg (2.0 mCi) 125iodine-B72.3 followed by intraoperative probe evaluation 2-3 weeks postinjection. Mean patient ages for the two groups were 60 years (range 28-75 years) and 63 years (range 43-77 years), respectively. Disease sites were primary in the large bowel in six patients and primary as well as metastatic in 22 patients. External scanning detected 111indium-B72.3 uptake in 1/5 primary lesions, 1/7 hepatic and 1/3 extrahepatic sites. The intraoperative gamma probe localized disease in 1/3 primary lesions, 7/11 hepatic and 3/3 extrahepatic sites. The intraoperative gamma probe had a sensitivity of 71% for detection of metastases compared with a 20% sensitivity using the external gamma scan method (P = 0.03). 125iodine-labelled B72.3 influenced the extent of the operative procedure in 4/14 (29%) patients; immunolocalization with external gamma detection did not alter the operative procedure in the 14 patients studied.(ABSTRACT TRUNCATED AT 250 WORDS)

Perioperative nutrition in cancer patients

Cancer patients have the highest incidence of protein-calorie malnutrition seen in hospitalized patients, with significant malnutrition occurring in more than 30% of cancer patients undergoing major upper gastrointestinal procedures. Clinically significant malnutrition occurs as a result of diminished nutrient intake, increased nutrient losses, and tumor-induced derangements in host metabolism. In the absence of adequate exogenous nutrients, the body utilizes endogenous substrates to satisfy the ongoing requirements of both host and tumor for energy and protein. In those patients with malignant obstruction of the gastrointestinal tract, the tumor itself may induce diminished nutrient intake. Present day treatment modalities including gastrointestinal resection, chemotherapy, and radiotherapy compound these metabolic derangements, further increasing the risk of postoperative morbidity and death. The presence of malnutrition in cancer patients has prognostic importance. In a review of more than 3000 cancer patients, DeWys and colleagues identified significantly improved survival in those patients without weight loss compared with those had lost 6% of their body weight (Am J Med 69:491-497, 1980). Other investigators have noted increased postoperative morbidity and mortality associated with malnutrition. Early hypotheses suggested that reversal of weight loss would improve survival. The development and refinements of enteral and parenteral nutrition have provided the opportunity for studying the relationship between nutritional supplementation and postoperative prognosis. Nutrition support is therefore often instituted to improve nutritional status and thereby reduce the risks of postoperative complications. This article addresses the beneficial role of preoperative nutrition therapy in cancer patients.

Presacral myelolipoma. Report of a case with fine needle aspiration cytology and immunohistochemical and histochemical studies

The cytomorphologic features of a case of the rare presacral myelolipoma, diagnosed by computed tomography (CT)-guided percutaneous fine needle aspiration (FNA) biopsy, are presented. It occurred in a 40-year-old man on prolonged steroid therapy for bronchial asthma. On the air-dried, Diff-Quik-stained smear, hematopoietic cells of all lineages and fragments of collapsed stroma were seen in a background of fat droplets. Megakaryocytic, myelocytic and eosinophilic lineages were further demonstrated by Factor VIII immunostain, chloroacetate esterase and LUNA-E histochemical stain, respectively. The reticulum stain of the resected tumor demonstrated that the hematopoietic cells and fat were supported by numerous reticulum fibers of varying thickness; that accounted for the collapsed stroma in the aspirated material. Presacral myelolipoma, occurring predominantly in female adults and presenting secondarily as a space-occupying lesion, is best regarded as encapsulated, heterotopic bone marrow supported by a network of reticulum fibers; it has a characteristic image on CT scan and can be diagnosed by FNA.

Loco-regional nodal relapse in melanoma

Two-hundred and seven patients without evidence of disease following lymph node dissection (LND) were stratified into three groups: Group A, lymph node relapse within the site of prior LND; Group B, lymph node relapse in a different, but regional, lymph node group; Group C, no lymph node relapse. Decreased survival was noted in both Groups A and B versus Group C. Prognostic factors were identified as: (i) axial or subungal/volar (subvolar) location and the number of positive lymph nodes at initial LND for nodal relapse within the same lymph node group; (ii) male gender, axial/subvolar location, and the number of histologically positive lymph nodes at initial LND for nodal relapse in a different, but regional lymph node group; (iii) relapse within the initial LND site for a decreased survival. Six of 10 patients with both axial/subvolar primaries and four or more positive lymph nodes developed a relapse within the dissection site post-LND. These prognostic factors describe a subset of patients who would be candidates for postoperative adjuvant local/regional and systemic therapy trials.

Azaserine-induced pancreatic foci: detection, growth, labelling index and response to raw soya flour

Atypical acinar cell foci were induced in the pancreases of rats by injection of azaserine. An incubation period of 6 weeks was sufficient for the detection of all glutathione S-transferase mu positive foci. In chow-fed rats, the labelling index of foci was 12-fold higher than normal pancreatic tissue. Feeding rats raw soya flour (RSF) for up to 20 weeks did not increase the number of foci per pancreas but did produce significant increases in labelling index and growth rate. In normal pancreatic tissue, the trophic response was complete after 4 weeks of RSF feeding. In foci, however, the trophic response to RSF was prolonged. Involution of normal pancreatic tissue was seen in rats fed RSF for 19 weeks and then switched to chow 1 week prior to death. No evidence for involution was seen in the foci of these animals, although a 40-fold reduction was seen in labelling index. The labelling index of these foci was reduced to the level seen in normal tissue of chow-fed rats. These results are consistent with increased cholecystokinin (CCK) responsiveness and CCK dependence in azaserine-induced pancreatic foci.

Colorectal cancer. Principles of postoperative follow-up

Monitoring patients after primary large bowel surgery for malignancy is predicated on the concept that early detection of recurrence may provide salvage treatment for cure. Knowledge of the pathologic site and stage provides important information as to the probability of recurrence and the patterns of failure that are likely to occur. Available methods to detect recurrence include clinical, roentgenographic, and serum tests that are done more frequently during the first 2 years after surgery. Monitoring plasma carcinoembryonic antigen levels can lead to identification of asymptomatic recurrences, but there is controversy about the curability of recurrences outside the liver. Newer techniques (such as computed tomographic portography, intraoperative ultrasonography, and radioimmunoguided surgery) provide greater diagnostic accuracy and lead to more appropriate procedures during "second-look" operations. For example, hepatic resection in properly selected patients offers up to a 30% chance of cure and should be pursued aggressively. A search for metachronous cancers by endoscopy also should be done. Knowledge of the potential and patterns of failure can provide a useful guide during the postoperative follow-up care of the patient with large bowel cancer.

Parenteral arginine infusion in humans: nutrient substrate or pharmacologic agent?

When given as a dietary supplement, arginine enhances lymphocyte mitogenesis and improves nitrogen balance. The purpose of this study was to evaluate arginine's ability to mediate these same effects when given as the sole nitrogen source with minimum additional calories. Thirty patients were randomized to receive 20 g/day arginine hydrochloride or a mixed amino acid solution (Travasol) by intravenous infusion for 7 days after abdominal operations. Mean patient age, body weight, gender ratios, and preoperative degree of weight loss were similar between groups. Mean plasma arginine and ornithine levels rose to 228 +/- 50 mumol/L and 191 +/- 76 mumol/L in the arginine group during infusion. Mean nitrogen balance was -8.8 g/day and -9.2 g/day in the arginine and Travasol groups, respectively. Mean lymphocyte stimulation indices to concanavalin A and phytohemagglutinin fell on postoperative day 1 in both groups. No significant differences in patterns of lymphocyte mitogenesis changes were noted between groups. The mean total number of circulating T cells increased in the arginine group at postoperative day 7. Thus, parenteral arginine infusion in postoperative patients provided comparable nitrogen balance to a balanced amino acid solution but did not increase peripheral blood lymphocyte mitogenesis. When arginine is given parenterally as the sole nitrogen source with minimal additional calories to postoperative patients, no enhancement of mitogen-stimulated lymphocyte proliferation could be demonstrated.

Enteral nutrition with supplemental arginine, RNA, and omega-3 fatty acids in patients after operation: immunologic, metabolic, and clinical outcome

The individual nutrients arginine, RNA, and omega-3 fatty acids improve immune function, but prospective trials have not demonstrated their effects on clinical outcome. Patients (n = 85) who underwent operation for upper gastrointestinal malignancies were randomized to receive the supplemental diet or a standard enteral diet after surgery. Clinical patient characteristics were similar between the two groups. Mean caloric intakes (1421 vs 1285 kcal/day) were similar between groups. Mean nitrogen intakes (15.6 vs 9.0 gm/day) and nitrogen balances (-2.2 vs -6.6 gm/day) measured in the first 20 patients were significantly greater in the supplemented group than in the standard group (p = 0.05). In vitro lymphocyte mitogenesis was measured in the first 31 patients and was decreased on postoperative day 1 in both groups, but normal levels were regained only in the supplemented group. In the cohort of 77 eligible patients, infectious and wound complications occurred significantly less often (11% vs 37%) in the supplemented group than in the standard group (p = 0.02). Linear logistic models for infectious/wound complications with control for the amount of nitrogen suggested (p = 0.10) dietary treatment as the major factor. Mean length of stay in the hospital was significantly shorter (p = 0.01) for the supplemented group (15.8 +/- 5.1 days) than for the standard group (20.2 +/- 9.4 days). These results suggest that postoperative enteral nutrition with supplemental arginine, RNA, and omega-3 fatty acids instead of a standard enteral diet significantly improved immunologic, metabolic, and clinical outcomes in patients with upper gastrointestinal malignancies who were undergoing major elective surgery.