Spontaneous changes in tumour cell dissemination to bone marrow in colorectal cancer.

AIM: The study aimed to evaluate the incidence of disseminated tumour cells (DTCs) in bone marrow (BM) preoperatively and during follow up and to correlate these with established risk factors in patients with colorectal cancer. METHOD: We prospectively studied BM in 57 patients using the anti-cytokeratin antibody A45-B/B3. RESULTS: The overall detection rate of DTCs was 23% with a similar detection rate through all stages of the disease. No significant association was found between the presence of DTCs and clinicopathological parameters. After a median follow up of 35.4 months, no differences were found in relapse and overall survival between patients with and without DTC preoperatively. In 31 of 45 patients with local disease, we performed a follow-up BM examination after 1 year. In 26% of the patients, the BM status had changed as compared with the preoperative finding. CONCLUSION: This is the first study to report the follow up of DTC in BM in colorectal cancer using the A45-B/B3 antibody. The presence of tumour cells in the preoperative BM had no impact on outcome. The BM status had changed after 12 months in a quarter of patients.

Caspase-cleaved cytokeratin 18 fragment (M30) as marker of postoperative residual tumor load in colon cancer patients.

BACKGROUND: Soluble cytokeratin 18 (CK18; M65) and a caspase-cleaved fragment of CK18 (M30) have been used as biomarkers, corresponding to tumor cell death and apoptosis, respectively. METHODS: In the present study, M30 was quantified for the first time in serum samples of colon cancer patients pre- and postoperatively as well as during chemotherapy. Minimal residual disease (MRD) was assessed preoperatively by detection of pan-cytokeratin antibody A45-B/B3-positive cells in bone marrow aspirates. RESULTS: Out of 46 patients, those with colon tumors of stages I and IV had significantly elevated M30 serum concentrations compared to controls (n = 23). In 31 colon cancer patients, M30 determinations were performed prior to and seven days after tumor surgery. A group of 24 patients exhibited a significant decrease of M30 in response to tumor removal, in contrast to seven patients who revealed either persistent or higher M30 levels postoperatively. The frequency of MRD was not significantly different for patients with decreasing (4/24) and persisting (3/7) M30. However, M30 correlated significantly with the increased number of recurrences within 36 months in the group with persisting M30 (4/7 versus 2/24, p = 0.032; hazard ratio 8.3, p = 0.016). In a group of patients (n = 10) receiving capecitabine/oxaliplatin chemotherapy (CapOx), transient increases in M30 did not correlate with responses. CONCLUSION: The data obtained within the present limited pilot study in colon cancer patients demonstrate that perioperative changes of M30 may indicate systemic residual tumor load and increased risk of recurrence warranting further evaluation of this marker of apoptosis in a larger prospective clinical trial.

Sacral nerve stimulation in patients with severe constipation.

PURPOSE: Constipation is frequently a multifactorial disease. This study was designed to evaluate the potential effects of sacral nerve stimulation for patients suffering from severe chronic constipation. METHODS: Nineteen patients suffering from pathologic colonic transit time or rectal outlet obstruction were included. Only patients with severe rectal outlet obstruction who needed digital manipulation for defecation or patients suffering from pathologic colonic transit constipation with less than two bowel movements per week were regarded as candidates. A temporary stimulation lead was implanted into the sacral foramen that showed the best muscular response. After an evaluation period, the stimulation electrode was removed. An improvement in constipation (more than 2 bowel movements per week or defecation without digital manipulation, respectively) during the test stimulation, as well as a recurrence of prestimulation constipation symptoms during the following surveillance period of three weeks were prerequisites for implanting the permanent sacral nerve stimulating system. RESULTS: All of the patients showed a positive motor response to acute needle stimulation. After the evaluation period, eight patients (42 percent) reported an improvement of constipation, and permanent systems were implanted successfully. During the median follow-up of 11 (range, 2-20) months, a significant improvement in the Wexner constipation score was observed compared with the preoperative baseline level (baseline: median: 23, range, 18-27; 12 months after implantation: median, 8, range, 4-13). After successful sacral nerve stimulation, patients also showed a significant improvement in their quality of life. CONCLUSIONS: Patients suffering from severe constipation are a new challenge for sacral nerve stimulation but further research on pelvic floor function is needed.

Sacral nerve stimulation for neurogenic faecal incontinence.

BACKGROUND: Sacral nerve stimulation (SNS) has emerged as a promising technique for the treatment of faecal incontinence. This study assessed the outcome of SNS in a cohort of patients with incontinence of neurological aetiology. METHODS: Thirty-six patients were included in a trial of SNS. Twenty-nine subsequently had a permanent implant. Evaluation consisted of a continence diary, anal manometry, saline retention testing and quality of life assessment. RESULTS: After a median follow-up of 35 (range 3-71) months, 28 patients showed a marked improvement in or complete recovery of continence. Incontinence to solid or liquid stool decreased from a median of 7 (range 4-15) to 2 (range 0-5) episodes in 21 days (P = 0.002). Saline retention time increased from a median of 2 (range 0-5) to 7 (range 2-15) min (P = 0.002). Maximum resting and squeeze anal canal pressures increased compared with preoperative values. Quality of life on all scales among patients who received a permanent implant increased at 12 and 24 months after operation. CONCLUSION: SNS is of value in selected patients with neurogenic faecal incontinence.

Aetiology and surgical management of toxic megacolon.

OBJECTIVE: The purpose of this article is to review the surgical management and outcome of toxic megacolon and to update the aetiology of toxic megacolon. PATIENTS AND METHOD: A retrospective chart review of three academic colorectal surgery units was undertaken. Over a period of 20 years, 70 patients with surgically managed toxic megacolon were identified: 32 men and 38 women, median age 63 years (range, 23-87 years). RESULTS: In 33 (48%) patients the main cause of toxic megacolon was inflammatory bowel disease. Thirty-seven (52%) patients had toxic megacolon of different aetiology. Sixty-three patients underwent colonic resection: 49 (70%) subtotal colectomies and 14 (20%) total colectomies, including 4 (6%) proctocolectomies. Seven (10%) patients had decompression (n=3) or faecal diversion (n=4) only. Forty-four of the resected patients underwent a Hartmann's procedure and an ileostomy; 13 (19%) patients had primary anastomoses, 11 (16%) ileorectal anastomoses (IRA) and 2 (3%) patients had ileal pouch-anal anastomosis (IPAA). Twenty-six (37%) patients subsequently had continuity restored. Total surgical complication rate was 19% (n=13), 8% (n=4) in patients treated with subtotal colectomy, 21% (n=3) in patients treated with total proctocolectomy and 86% (n=6) in patients treated with either decompression or diversion. The total mortality rate was 16% (n=11). CONCLUSIONS: Toxic colitis complicated by toxic megacolon can occur after various diseases of the colon and remains a life-threatening disorder associated with a significant risk of postoperative complications. Subtotal colectomy with ileostomy remains the procedure of choice. Surgical colonic decompression with faecal diversion alone is associated with a high rate of complications.

Improving the safety of laparoscopic cholecystectomy: the routine use of preoperative magnetic resonance cholangiography.

BACKGROUND: The aim of this study was to determine the value of routinely performed preoperative magnetic resonance cholangiography (MRC) in detecting common bile duct (CBD) stones in patients stated to undergo elective laparoscopic cholecystectomy. In addition, we used MRC to investigate possible variants of the cystic duct. METHODS: Magnetic resonance cholangiography was performed preoperatively in 773 patients (311 male and 462 female; median age 55 years, range 16-91) who had no clinical signs of cholestasis prior to undergoing elective laparoscopic cholecystectomy. In cases where the MRC was positive for CBD stones, endoscopic retrograde cholangiopancreatiography (ERCP) was then performed. A total of 532 patients were available for continuous postoperatively follow-up (median 54 months, range 36-85). In 462 patients (247 female, and 215 male), MR images were also reviewed for variants of the cystic duct. RESULTS: In 705 patients (91%), MRC was negative for CBD stones. In 64 patients (9%) MRC was positive. Of these patients, 47 (6%) had CBD stones on ERCP. In 12 patients (2%), MRC was false positive. In five cases (0.6%), ERCP had an inconclusive result postoperative follow-up (532 patients, or 69%) revealed evidence of CBD stones in three patients (10.4%) despite a preoperative negative MRC result. Anatomical variants in the course of the cystic duct and its confluence with the common bile duct were found in 27 of 462 patients (6%). CONCLUSIONS: Magnetic resonance cholangiography proved to be a reliable screening technique in the preoperative evaluation of patients with silent CBD stones. Imaging of the course of the cystic duct is possible in a high percentage of cases. Therefore, MRC can be recommended as a screening technique before laparoscopic cholecystectomy.

[Collateral circulation of the left colon: historic considerations and actual clinical significance]. / Die kollaterale Gefässversorgung des linken Hemikolons. Historische Beobachtungen und aktuelle klinische Bedeutung.

INTRODUCTION: The arterial communication between the superior and inferior mesenteric arteries is important in surgery of the colon and aorta. METHODS: The anastomosis between the median colic artery (ACM) and the superior colic artery (AMS) was studied on 52 cadavers (32 female, 20 male). The length of the artery was measured using a flexible scale, and its diameter was determined at three different locations (origin, middle, end). RESULTS: The median lengths of the arteries were: 6.8 cm (range 3.9-9.7) for ACM, 12.2 cm (range 7-17.4) for ACS, and 23 cm (range 13.6-34.2) for margin artery. The median diameters were: 3.4 mm (range 2.7-4.1) for ACM, 3.1 mm (range 2.1-4.1) for ACS, and 2.7 mm (range 2-3.4) for margin artery. In 9.6% of the cadavers ( n=5), additional anastomoses between the AMS and inferior mesenteric arteries were proven. In 90.4% ( n=47), only margin arteries were found. SUMMARY: The low incidence of an additional communication (Riolan's arch) and possible additional impairment of the blood supply should be taken into account during operation.

[Immunocytochemical and molecular detection of minimal residual disease in blood and bone marrow in colorectal cancer]. / Immunzytochemischer und molekularer Nachweis der minimalen Resterkrankung in Blut und Knochenmark bei kolorektalem Karzinom.

Immunocytochemical and molecular biological methods to analyze minimal residual disease (MRD) in colorectal cancer in blood and bone marrow were compared. The concept of a study in the Donauspital will be presented which will permit a comparative judgement of minimal residual disease in blood and bone marrow in patients with colorectal cancer.

p53 expression in fallopian tube carcinomas.

Sixty-three women treated for primary carcinoma of the fallopian tube (PFTC) from 1980-1995 were retrospectively analyzed to study the impact of p53 expression on survival in primary carcinoma of the fallopian tube. The mean age of the patients was 61.2 years (range 37.3-80.2). Twenty-four (38%) patients were FIGO stage I, 11 (18%) stage II, 19 (30%) stage III and nine (14%) stage IV. Complete radical resection was achieved in 45 (71%) patients. In 56 (89%) women, surgery involved removal of the uterus, the adnexa, and/or the omentum or lymph nodes. Adjuvant therapy consisted of either chemotherapy (n: 31; 49%) or irradiation (n: 21; 33%). The 5-year survival rate for all cases was 43%. For stages I+II and III+IV the 5-year survival rate was 59 and 19%, respectively (P<0.00001). Twelve samples (19%) were p53-negative (tumours with <10% of nuclear staining) and 51 (81%) samples were p53 positive tumours with >10% of nuclear staining. The median survival for the p53-negative group was 40 and 21 months for the p53 positive group. No statistical significance between p53 expression and different FIGO stages was observed, however, a trend for a slightly better survival for the p53-negative group was observed.

Identification of women with early breast cancer by analysis of p43-positive lymphocytes.

Regular screening mammographies and increasing knowledge of high-risk groups have resulted in an improvement in the rate of detection of smaller malignant lesions. However, uncertain minimal mammographic features frequently require further costly and often uncomfortable investigation, including repeat radiological controls or surgical procedures, before cancerous lesions can be identified. Placental isoferritin (p43), a protein with immunosuppressive effects, has been detected on the surface of lymphocytes taken from peripheral blood in patients with breast cancer. In this study we evaluated the sensitivity and specificity of the expression of p43-positive lymphocytes as a marker in early stage breast cancer and also investigated its expression on T-cell subpopulations. The presence of p43-positive lymphocytes was investigated using the monoclonal antibody CM-H-9 and flow cytometry in 76 women with controversial, non-palpable mammographic findings who were undergoing surgical biopsy. Patients with early breast cancer (n = 48) had significantly higher p43-positive cell values (median 3.83%, range 0.98-19.4) than patients with benign lumps (n = 28, median 1.43%, range 0.17-3.7) or controls (n = 22, median 1.3%, range 0.4-1.87) (P < 0.0001). At a cut-off level of 2% p43-positive cells a sensitivity of 91.7% and a specificity of 89.3% for detection of breast cancer could be reached. While the median ratio of total CD4+/CD8+ cells was 2.6, a ratio of 1.3 was found for the p43-positive subpopulation (P < 0.001), thus indicating a significant link between p43 and CD8+ cells. The determination of p43-positive lymphocytes in peripheral blood could serve as an additional diagnostic tool in patients with controversial mammographic findings and could also reduce the need for cost-intensive and often uncomfortable management of these patients.

[Anal sphincter restoration using dynamic graciloplasty--results of 50 patients]. / Analer Schliessmuskelersatz mittels dynamischer Gracilisplastik--Ergebnisse der Anwendung an 50 Patienten.

During the period from 1992 to 1998, 50 patients underwent anal sphincter restoration by dynamic graciloplasty for primary (n = 26) or secondary (n = 6) total anorectal reconstruction (TAR) following abdominoperineal rectal resection (APR) or acquired (n = 9) or congenital (n = 9) fecal incontinence, respectively. Forty-seven patients were operated on by a single-stage procedure using a modified technique for the muscle wrap ("split sling"). Muscle fiber transformation by controlled stimulation was achieved at the beginning of the learning curve within 8 weeks and in the meantime within 4 weeks. Rectal injury (n = 10) turned out to be the most serious postoperative complication and was observed mainly in patients following TAR (n = 8). As the most prominent functional problem constipation in patients following TAR hampered the postoperative functional result; however, this was overcome by regular enemas. An improvement in the continence status was observed in 80% of the patients treated for fecal incontinence, and following APR 66% of the patients had acceptable results without a permanent colostomy.

Activated lymphocytes from breast cancer patients express the characteristics of type 2 helper cells--a possible role for breast cancer-associated p43.

P43, a breast cancer-associated antigen, has been repeatedly described as an immunosuppressive factor. The objective of the present study was to investigate whether immune dysregulation induced by p43 affects the profile of cytokines secreted by mitogen-stimulated lymphocytes in breast cancer patients as compared with stimulated lymphocytes in women with benign tumors. The study consisted of 32 women undergoing surgical excision for a suspicious lesion in their breast. Histology revealed malignant breast disease in 20 patients and benign lesions in 10 patients. Lymphocytes isolated from peripheral blood were activated by Conconavalin A (Con A) with and without the addition of p43 and the concentrations of cytokines (IL-2, TNF-alpha, IFN-gamma, IL-4, IL-10 and IL-6) secreted into the culture medium were determined. Lymphocytes of patients with malignant breast disease stimulated with Con A secreted a significantly higher concentration of IL-10 compared with lymphocytes of patients with benign tumors. No significant differences were found between the two groups regarding the levels of IL-2, TNF-alpha, IFN-gamma and IL-4. Cytokine concentrations were analyzed according to the type 1/type 2 cytokine profile (IL-2, TNF and IFN-gamma and IL-4, IL-6 and IL-10, respectively). This analysis revealed no significant differences in IL-2, TNF or IFN-gamma between benign and malignant tumors. However, in the type 2 cytokines, lymphocytes from cancer patients secreted significantly higher levels of IL-4 (27.3 +/- 7.2 U/ml) and IL-10 (44.1 +/- 22.3 U/ml) than did the lymphocytes from patients with benign disease (21.4 +/- 7.3 and 1.8 +/- 0.3 U/ml, respectively). The addition of p43 to the culture medium significantly enhanced the levels of IL-4 secreted by lymphocytes in both groups of patients (malignant disease, from 27.3 +/- 9.2 to 40.7 +/- 6.3 U/ml; benign disease, from 21.4 +/- 7.3 to 28.4 +/- 2.1 U/ml). P43 antigen significantly enhanced the low levels of IL-10 in the benign lymphocytes (from 1.8 +/- 0.4 to 8.4 +/- 1.5 U/ml) while the high levels of IL-10 secreted by the PBL in patients with malignant tumors were not significantly increased (44.1 +/- 22.3 versus 50.1 +/- 12.6 U/ml). The study showed a difference in the immune response of lymphocytes between malignant and benign tumors. When the current results were analyzed according to the type of response, i.e. in terms of whether at least two cytokines of either type 1 or type 2 were elevated, a significant type 2 response was observed in the PBL of patients with malignant breast cancer (IL-10 and IL-4). These results may explain why antitumor response is impaired in patients with breast cancer.

A 15-year overview of management and prognosis in primary fallopian tube carcinoma. Austrian Cooperative Study Group for Fallopian Tube Carcinoma.

143 women treated in 28 departments from 1980 to 1995 were retrospectively analysed to study the impact of prognostic factors in primary carcinoma of the fallopian tube. The mean age of the patients was 62.5 years. Sixty (42%) tumours were FIGO stage I, 28 (20%) stage II, 38 (27%) stage III, 17 (12%) stage IV. Complete radical resection was achieved in 102 (71%) patients. In 122 (85%) women, surgery involved removal of the uterus, the adnexa, and/or the omentum or lymph nodes. Postoperative therapy consisted of either irradiation (n = 40; 28%) or chemotherapy (n = 70; 49%); 33 women (23%) did not receive any treatment after surgery. The 5-year survival rate for all cases was 43%. The 5-year survival rate was 59% for stages I and II and 19% for stages III and IV (P < 0.00001). FIGO stage, histological grade and presence of residual tumour had an independent prognostic impact in multivariate analysis. In order to investigate the role of p53 in primary fallopian tube carcinomas, we analysed the immunohistochemical expression of p53 protein regarding survival and FIGO stage in 63 patients (44%). No statistical significance was observed.

Placental isoferritin in pregnancies with small-for-gestational age fetuses.

The secretion of placental isoferritin (PLF) during pregnancy could be responsible for the diminished immunoreaction of maternal lymphocytes against the embryo. In this study, serum levels of PLF in 335 pregnant women were correlated with birth weight, percentile of birth weight, gestational age, and pulsatility index of the uterine artery, as well as with diastolic notching. Women with small-for-gestational age (SGA) infants (birth weight below or equal to the tenth percentile) showed significantly lower PLF levels (11.7 U/ml) compared with women whose newborns were of normal weight (19.4 U/ml) (P < 0.05). In line with this finding, a strong correlation was observed between PLF levels and the percentile of birth weight, pulsatility index of the uterine artery, and the presence of diastolic notching. The strong correlation of low PLF values and SGA newborns suggests that determination of PLF could serve as a marker to identify women at risk of having such babies.

[The value of adjuvant and neoadjuvant chemotherapy in treatment of stomach carcinoma]. / Die Bedeutung der adjuvanten und neoadjuvanten Chemotherapie in der Behandlung des Magenkarzinoms.

The incidence of gastric adenocarcinoma has decreased dramatically in most Western countries over the past five decades. However, the five-year survival rate remains poor and late diagnosis is one of the main reasons for the lack of marked improvement in outcome. More than 50% of the patients found to have advanced local (stage T III), or systemic (stage T IV) gastric cancer at the time of diagnosis. This review article examines the current state of chemotherapeutic regimens additive to surgery, based on a computer-supported literature search (MED-LINE and CANCERLIT). Since 1980 15 randomized studies have been performed to evaluate the efficacy of systemic adjuvant chemotherapy. Of these, 13 were published in the Western English literature and 2 were Japanese studies, encompassing a total of over 2000 patients. In 3 studies adjuvant chemotherapy was administered intraperitoneally. An evaluation of these studies failed to demonstrate any advantage for the outcome of chemotherapy on patients with curative resected gastric carcinoma. Thus, according to present knowledge, this form of adjuvant treatment cannot be recommended for routine clinical management. In order to evaluate the effect of neoadjuvant chemotherapy, 17 randomized studies have been reviewed. In 6 studies (3 Western studies, 3 Japanese studies) neoadjuvant chemotherapy was investigated in patients with potentially curative resectable gastric carcinoma. 11 Western studies reported the results of neoadjuvant chemotherapy in cases of locally advanced disease. It appears that neoadjuvant chemotherapy of locally advanced non-resectable gastric cancer in patients who do not have distant metastases and/or "carcinosis peritonei" reduces tumor size in 30-40% of the patients, thus enabling radical resection in a second look operation. The efficacy of neoadjuvant chemotherapy in potentially resectable gastric carcinoma cannot be definitely assessed at the present time since only scant, preliminary findings are available. Future goals for the treatment of gastric carcinoma should include studies evaluating preoperative chemotherapy using effective, but less toxic substances, based on exact tumor-staging by means of endoluminal sonography. Furthermore, research projects investigating the value of intraperitoneal therapeutic regimens such as hyperthermic chemoperfusion or intraperitoneal instillation of the requisite substances in the prevention of intraperitoneal carcinomatosis and local recurrence will be of great importance.

Immunosuppressive activity of lymphocyte mitogenesis by breast cancer-associated p43.

Placental isoferritin (PLF), an acidic isoform of ferritin, and its unique superheavy chain of 43 kDa (p43) has been described to be synthesized by human breast cancer cells. Physiologically, p43 PLF produced by the placenta is involved in immune suppression of maternal lymphocytes aimed at fetal antigens. A study was carried out to elucidate a paradigm of p43 occurrence in breast cancer patients. Immunosuppression of cytotoxic CD8+ lymphocytes was measured via inhibition of blast transformation in concanavalin A (ConA) stimulated peripheral blood lymphocytes (PBL) using 3H-thymidine uptake in vitro. PBLs were cultivated from 29 women having benign lesions in the breast as well as from 41 patients with breast adenocarcinoma. In breast cancer patients addition of p43 significantly inhibited the activation of lymphocytes proliferation by ConA compared to women with benign tumors. The addition of indomethacin or levamisole did not influence this inhibitory effect of p43 in breast cancer patients. Presence of interleukin-2 in cultures was able to overcome the inhibitory effect of p43 on CD8+ lymphocytes proliferation from women having breast adenocarcinomas and to increase its value in patients with benign lesions.

Immunosuppression by breast cancer associated p43-effect of immunomodulators.

It has been previously shown that p43- a breast cancer associated antigen-has immunosuppressive properties. The present study was carried out in order to elucidate the pathomechanisms of immunosuppression in breast cancer patients influenced by the expression of p43. Lymphocytes were cultured from blood of 29 women with benign lesions in the breast as well as from 41 female patients with breast cancer. Lymphocyte stimulation was performed by addition of Concanavalin (Con A) in cultures with lymphocytes alone (CONLYM) or in lymphocytes incubated with p43 (CONAg). In other series immunomodulation was tried by addition of indomethacin (INDLYM, INDAg), levamisole (LEVLYM, LEVAg), or interleukin-2 (ILLYM, ILAG). In breast cancer patients, addition of p43 significantly inhibited the activation of lymphocyte proliferation by Con A compared to women with benign tumors. The addition of indomethacin or levamisole did not influence this inhibitory effect of p43 in breast cancer patients. Contrary to these observations, addition of IL-2 resulted in increased proliferation of lymphocytes from patients with benign as well as malignant tumors, which was inhibited after addition of p43. Analysis of the correlation of the immunosuppressive properties of p43 in correlation with prognostic factors for breast cancer showed evidence for a stronger activity of p43 in early stage tumors (i.e. smaller than 2 cm, lymph node negative, histologic grading GI), confirming previous observations of a higher expression of p43 in early stages of breast cancer.

Alterations of cell surface antigens induced by placental isoform of ferritin in human carcinoma cell lines.

AIM: the ability of the breast cancer-associated placental acid isoform of ferritin (p43-PLF) to modulate cell surface expression of HLA, CD59 (protectin) and CD66 antigen (adhesion antigen related to CEA) was examined. METHODS: the expression of these antigens in human breast carcinoma cell lines BT-20, T47D and MDA-MB-468 was determined with the aid of flow cytometry and monoclonal antibodies. RESULTS: PLF induced a transient up-regulation followed by a down regulation of cell surface protectin (CD59 antigen) on the cell surface of T47D and to a lesser extent, BT-20 human breast carcinoma cell lines. Furthermore, PLF down-regulated cell surface expression of CEA-related CD66 antigen on both these cell lines. No PLF-induced alterations of protectin, CD66 antigen and HLA class I antigen were found on the MDA-MB-468 breast cancer cell line. CONCLUSIONS: breast cancer-associated p43 induces alterations of the expression of cell surface molecules in breast cancer cells which could have an effect on the modulation of cancer cell adhesive interactions.