Negative predictive value of preoperative computed tomography in determining pathologic local invasion, nodal disease, and abdominal metastases in gastric cancer.

BACKGROUND: Before undergoing curative-intent resection of gastric adenocarcinoma (ga), most patients undergo abdominal computed tomography (ct) imaging to determine contraindications to resection (local invasion, distant metastases). However, the ability to detect contraindications is variable, and the literature is limited to single-institution studies. We sought to assess, on a population level, the clinical relevance of preoperative ct in evaluating the resectability of ga tumours in patients undergoing surgery. METHODS: In a provincial cancer registry, 2414 patients with ga diagnosed during 2005-2008 at 116 institutions were identified, and a primary chart review of radiology, operative, and pathology reports was performed for all patients. Preoperative abdominal ct reports were compared with intraoperative findings and final pathology reports (reference standard) to determine the negative predictive value (npv) of ct in assessing local invasion, nodal involvement, and intra-abdominal metastases. RESULTS: Among patients undergoing gastrectomy, the npv of ct imaging in detecting local invasion was 86.9% (n = 536). For nodal metastasis, the npv of ct was 43.3% (n = 450). Among patients undergoing surgical exploration, the npv of ct for intra-abdominal metastases was 52.3% (n = 407). CONCLUSIONS: Preoperative abdominal ct imaging reported as negative is most accurate in determining local invasion and least accurate in nodal assessment. The poor npv of ct should be taken into account when selecting patients for staging laparoscopy.

Topotecan and cyclophosphamide in adults with relapsed sarcoma.

UNLABELLED: Background. The combination of topotecan and cyclophosphamide (TC) has activity in pediatric patients with recurrent sarcoma, especially Ewing's sarcoma (EWS). We sought to determine the toxicity of and response to TC in adults with recurrent sarcoma. Patients and Methods. Adults treated with TC from 2005 to 2010 were reviewed who received T = topotecan at 0.75 mg/m(2)/day (days 1-5) and C = cyclophosphamide at 250 mg/m(2)/day (days 1-5) every 21 days. Results. Fifteen patients, median age 31 years (range 17.5-56) had nonpleomorphic rhabdomyosarcoma (RMS, n = 6), EWS, n = 5, synovial sarcoma (SS, n = 2) leiomyosarcoma (LMS, n = 1), and desmoplastic small round cell tumour (DSRCT, n = 1). Median time to progression was 2.5 months (range 1.6-13.0). Partial responses were seen in 2/6 RMS and 1/2 SS. Stable disease was seen in 2/5 EWS, 1/2 SS and 1 DSRCT. The most common reason for stopping treatment was progressive disease 12/15, (80%). Hematologic toxicity was common; 7 (47%) patients required blood product transfusion, 5 (33%) patients had fever/neutropenia. At median follow-up time of 7.7 months, all but 1 patient had died of disease. CONCLUSION: TC combination is tolerable but has only modest activity in adults with recurrent sarcoma. Other regimens deserve exploration for this high-risk group of patients.

Nitric oxide derived from L-arginine impairs cytoplasmic pH regulation by vacuolar-type H+ ATPases in peritoneal macrophages.

The ability of macrophages (Møs) to function within an acidic environment has been shown to depend on cytoplasmic pH (pHi) regulation by vacuolar-type H+ ATPases. Møs metabolize L-arginine via an oxidative pathway that generates nitric oxide, nitrate, and nitrite. Since each of these products could potentially inhibit vacuolar-type H+ ATPases, we investigated the effect of L-arginine metabolism on Mø pHi regulation in thioglycolate-elicited murine peritoneal Møs. H+ ATPase-mediated pHi recovery from an imposed cytoplasmic acid load was measured fluorometrically. When Møs were incubated with L-arginine (0.25-2.0 mM), their rate of pHi recovery declined progressively from 2 to 6 h of incubation. By contrast, the recovery rate of cells incubated in arginine-free medium remained stable over the same period. The impairment of pHi recovery was specific for L-arginine, and was blocked competitively by NG-monomethyl-L-arginine, demonstrating its dependence on L-arginine metabolism. In addition, the inhibition of pHi recovery was enhanced by lipopolysaccharide, an agent known to stimulate L-arginine metabolism by Møs. Scavenging the L-arginine metabolite nitric oxide with either ferrous sulphate or ferrous myoglobin prevented the inhibition of pHi recovery, implying that L-arginine-derived nitric oxide was the species responsible for the inhibition. This concept was supported by the finding of elevated nitrite levels in the supernatant of cells incubated in L-arginine. Furthermore, incubation of Møs with sodium nitroprusside mimicked the L-arginine-dependent inhibition of H+ ATPase activity. Treatment with the cyclic GMP analogue, 8-bromoguanosine 3':5'-cyclic monophosphate, similarly impaired Mø pHi recovery, suggesting that a nitric oxide-stimulated elevation of cyclic GMP may contribute to the L-arginine-dependent inhibition of pHi regulation.

Qualitative assessment of patient experiences following sacrectomy.

BACKGROUND AND OBJECTIVES: The primary objective was to investigate patient experiences following sacral resection as a component of curative surgery for advanced rectal cancers, soft tissue and bone sarcomas. METHODS: Qualitative methods were used to examine the experiences, decision-making, quality of life, and supportive care needs of patients undergoing sacrectomy. Patients were identified from two prospective databases between 1999 and 2007. A semi-structured interview guide was generated and piloted. Patient interviews were transcribed verbatim and analyzed using standard qualitative research methodology. Grounded theory guided the generation of the interview guide and analysis. RESULTS: Twelve patients were interviewed (6 female, 32-82 years of age). The mean interview time was 34 min. Five themes were identified, including: (1) the life-changing impact of surgery on both patients' and their family's lives, (2) patient satisfaction with immediate care in hospital, (3) significant chronic pain related to sacrectomy, (4) patients' need for additional information regarding long-term recovery, and (5) patients' gratitude to be alive. CONCLUSIONS: Sacrectomy is a life-changing event for patients and their families. Patients undergoing sacrectomy need further information regarding the long-term consequences of this procedure. This need should be addressed in both preoperative multi-disciplinary consultations and at follow-up visits.

Germline variants and phenotypic spectrum in a Canadian cohort of individuals with diffuse gastric cancer.

Background: CDH1 pathogenic variants (pvs) cause most cases of inherited diffuse gastric cancer (dgc), but have low detection rates and vary geographically. In the present study, we examined hereditary causes of dgc in patients in Ontario. Methods: CDH1 testing through single-site or multi-gene panels was conducted for patients with dgc meeting the 2015 International Gastric Cancer Linkage Consortium (igclc) criteria, or with isolated dgc at less than 50 years of age, or with a strong family history of cancer identified at the Zane Cohen Centre (zcc). All CDH1-positive patients at zcc, regardless of cancer history, were summarized. Results: In 15 of 85 patients with dgc (17.6%), a pv or likely pv was identified through CDH1 single-site (n = 43) or multi-gene panel (n = 42) testing. The detection rate was 9.4% overall (8 of 85) and 11% using igclc criteria (7 of 65). No CDH1 pvs were identified in patients with isolated dgc at less than 40 years of age, but 1 pv was identified in a patient with isolated dgc at less than 50 years of age. Multi-gene panels identified 9 pvs (21.4%), including CDH1, STK11, ATM, BRCA2, MLH1, and MSH2. Review of 81 CDH1 carriers identified 10% with dgc (median age: 48 years; range: 38-59 years); 41% were unaffected (median age: 53 years; range: 26-89 years). Observed malignancies other than dgc or lobular breast cancer (lbc) included colorectal, gynecologic, kidney or bladder, prostate, testicular, and ductal breast cancers. Lobular-breast cancer was seen only in 3 families. Conclusions: In Ontario, the detection rate of CDH1 pvs in patients with dgc was low: no pvs were identified in patients with isolated dgc at less than 40 years of age, and 1 was identified in a patient with isolated dgc at less than 50 years of age. Isolated lbc with no dgc was observed in CDH1-positive families, as were pathology-confirmed nondgc or non-lbc malignancies, which had not previously been reported. Given a phenotype that overlaps with other hereditary conditions, multi-gene panels are recommended for all patients with dgc at less than 50 years of age and for those meeting igclc criteria.

In situ hypothermic liver preservation during radical liver resection with major vascular reconstruction.

BACKGROUND: The in situ hypothermic liver preservation technique may allow a more aggressive approach to tumours of the caval confluence and/or all three hepatic veins, which would otherwise be deemed irresectable. METHODS: All descriptive data regarding patient demographics, operative characteristics, perioperative complications and outcomes of nine patients in whom this technique was used were collected prospectively. RESULTS: Seven patients underwent liver trisegmentectomy and two had primary retrohepatic venal caval resection. Total hepatic vascular occlusion with in situ hypothermic liver preservation was used for venous reconstruction in all patients. The vena cava was reconstructed with prosthetic graft in seven patients. All main hepatic veins were reconstructed in the seven liver resections. In situ hypothermic liver preservation was well tolerated as evidenced by preserved hepatic synthetic function early after operation. One patient died 66 days after surgery. There were two recurrences after a median follow-up of 14 (range 2-33) months; local recurrence was identified in one patient after 4 months and distant metastasis in another after 8 months. CONCLUSION: The in situ hypothermic liver preservation technique appears to be a useful adjunct to radical hepatobiliary tumour excision procedures that require total hepatic vascular exclusion and major vascular reconstruction.

Glove and instrument changing to prevent tumour seeding in cancer surgery: a survey of surgeons' beliefs and practices.

Background: Some surgeons change gloves and instruments after the extirpative phase of cancer surgery with the intent of reducing the risk of local and wound recurrence. Although this practice is conceptually appealing, the evidence that gloves or instruments act as vectors of cancer-cell seeding in the clinical setting is weak. To determine the potential effect of further investigation of this question, we surveyed the practices and beliefs of a broad spectrum of surgeons who operate on cancer patients. Methods: Using a modified Dillman approach, a survey was mailed to all 945 general surgeons listed in the College of Physicians and Surgeons of Ontario public registry. The survey consisted of multiple-choice and free-text response questions. Responses were tabulated and grouped into themes, including specific intraoperative events and surgeon training. Predictive variables were analyzed by chi-square test. Results: Of 459 surveys returned (adjusted response rate: 46%), 351 met the inclusion criteria for retention. Of those respondents, 52% reported that they change gloves during cancer resections with the intent of decreasing the risk of tumour seeding, and 40%, that they change instruments for that purpose. The proportion of respondents indicating that they take measures to protect the wound was 73% for laparoscopic cancer resections and 31% for open resections. Training and years in practice predicted some of the foregoing behaviours. The most commonly cited basis for adopting specific strategies to prevent tumour seeding was "gut feeling," followed by clinical training. Most respondents believe that it is possible or probable that surgical gloves or instruments harbour malignant cells, but that a cancer recurrence proceeding from that situation is unlikely. Conclusions: There is no consensus on how gloves and instruments should be handled in cancer operations. Further investigation is warranted.

Outcomes by treatment modality in elderly patients with localized gastric and esophageal cancer.

Background: We aimed to assess current treatment patterns and outcomes in elderly patients with localized gastric and esophageal (ge) cancers. Methods: This retrospective analysis considered patients 75 years of age or older with ge cancers treated during 2012-2014. Patient demographics and tumour characteristics were collected. Overall survival (os) and disease-free survival were assessed by univariable and multivariable Cox proportional hazards regression, adjusting for demographics. Logistic regression analyses were used to examine factors affecting treatment choices. Results: The 110 patients in the study cohort had a median age of 81 years (range: 75-99 years). Primary disease sites were esophageal (55%) and gastric (45%). Treatment received included radiation therapy alone (29%), surgery alone (26%), surgery plus perioperative therapy (14%), chemoradiation alone (10%), and supportive care alone (14%). In multivariable analyses, surgery (hazard ratio: 0.48; 95% confidence interval: 0.26 to 0.90; p = 0.02) was the only independent predictor for improved os. Patients with a good Eastern Cooperative Oncology Group performance status (p = 0.008), gastric disease site (p = 0.02), and adenocarcinoma histology (p = 0.01) were more likely to undergo surgery. Conclusions: At our institution, few patients 75 years of age and older received multimodality therapy for localized ge cancers. Outcomes were better for patients who underwent surgery than for those who did not. To ensure optimal treatment selection, comprehensive geriatric assessment should be considered for patients 75 years of age and older with localized ge cancers.

Late mitotic failure in mice lacking Sak, a polo-like kinase.

Polo-like kinases in yeast, flies, and mammals regulate key events in mitosis. Such events include spindle formation at G2/M, the anaphase-promoting complex (APC) at the exit from mitosis, the cleavage structure at cytokinesis, and DNA damage checkpoints in G2/M. Polo-like kinases are distinguished by two C-terminal polo box (pb) motifs, which localize the enzymes to mitotic structures. We previously identified Sak, a novel polo-like kinase found in Drosophila and mammals. Here, we demonstrate that the Sak kinase has a functional pb domain that localizes the enzyme to the nucleolus during G2, to the centrosomes in G2/M, and to the cleavage furrow during cytokinesis. To study the role of Sak in embryo development, we generated a Sak null allele, the first polo-like kinase to be mutated in mice. Sak(-/-) embryos arrested after gastrulation at E7.5, with a marked increase in mitotic and apoptotic cells. Sak(-/-) embryos displayed cells in late anaphase or telophase that continued to express cyclin B1 and phosphorylated histone H3. Our results suggest that Sak is required for the APC-dependent destruction of cyclin B1 and for exit from mitosis in the postgastrulation embryo.

Clinical features and outcomes of 20 patients with abdominopelvic desmoplastic small round cell tumor.

INTRODUCTION: Desmoplastic small round cell tumor (DSRCT) is a rare mesenchymal malignancy. We describe our experience with treating DSRCT at a large sarcoma referral center. METHODS: A retrospective chart review was performed on DSRCT patients referred to our institution (1998-2014). Pathology specimens were reviewed to confirm the diagnosis. Clinical and imaging were extracted and summarized with descriptive statistics. Univariate analysis was performed to evaluate the association between patient, tumor, and treatment variables and overall survival (OS). RESULTS: In this study cohort of 20 patients, median age at presentation was 29 y (range 18-43) and 90% were male. Fifty-five percent presented with metastasis. Patients underwent chemotherapy (n = 20), radiation therapy (n = 3), and cytoreductive surgery (CRS) (n = 5). Median OS was 22 m (interquartile range: 12-28 m). Five-year OS rate was 20%. Extra-abdominal metastasis was associated with a higher hazard ratio (HR) of mortality (HR: 3.1, 95% C.I. 1.0-9.4, p = 0.04), while CRS improved OS (HR: 0.1, 95% C.I. 0.03-0.7, p = 0.02). CONCLUSIONS: Despite aggressive treatment, less than half of the patients were dead of DSRCT within 2 years of presentation. Although a select group of patients who underwent CRS had improved OS, novel treatments are urgently needed.

Regulation of cytoplasmic pH in resident and activated peritoneal macrophages.

Cytoplasmic pH (pHi) has been shown to be an important determinant of the activity of the NADPH oxidase in phagocytic cells. We hypothesized that a difference in pHi and/or its regulation existed between activated and resident macrophages (RES MOs) which might explain the increased NADPH oxidase activity observed in the former. The pHi of RES and lipopolysaccharide (LPS)-elicited MOs was examined using the fluorescent dye BCECF. Resting pHi did not differ between resident (RES) and elicited (ELI) MOs (7.16 +/- 0.05 and 7.20 +/- 0.05, respectively). pHi recovery after intracellular acid loading was partially dependent on the presence of Na+ in the extracellular medium, and was partially inhibited by the Na+/H+ antiport inhibitor, amiloride. At comparable pHi, the rate of acid extrusion during recovery was not different in RES and ELI MOs (1.48 +/- 0.12 and 1.53 +/- 0.06 mM/min, respectively). In both RES and ELI MOs, approx. 40% of total pHi recovery was insensitive to amiloride and independent of extracellular Na+. In both RES and ELI MOs, stimulation with TPA resulted in a biphasic pHi response: an initial acidification followed by a sustained alkalinization to a new steady-state pHi. This alkalinization was Na(+)-dependent and amiloride-sensitive, consistent with a TPA-induced increase in Na+/H+ antiport activity. The new steady-state pHi attained after TPA stimulation was equivalent in RES and ELI MOs (7.28 +/- 0.04 and 7.31 +/- 0.06, respectively), indicating comparable stimulated Na+/H+ antiport activity. However, the initial acidification induced by TPA was greater in ELI than in RES MOs (0.18 +/- 0.02 vs. 0.06 +/- 0.02 pH unit, respectively, P less than 0.05). The specific NADPH oxidase inhibitor diphenylene iodonium (DPI) completely inhibited the respiratory burst but reduced the magnitude of this pHi reduction by only about 50%. This suggested that the TPA-induced pHi reduction was due in part to acid produced via the respiratory burst, and in part to other acid-generating pathways stimulated by TPA.

Lipopolysaccharide impairs macrophage cytoplasmic pH regulation under conditions simulating the inflammatory microenvironment.

Within the acidic inflammatory milieu, macrophages (m phi s) must maintain their cytoplasmic pH (pHi) within a range conducive to optimal function. It was previously shown that metabolism of L-arginine at concentrations present in vitro in RPMI medium (1.14 mM) impairs the ability of m phi s to regulate pHi. However, concentrations of L-arginine in vivo reportedly range from approximately 100 microM in serum to less than or equal to 50 microM in wounds. To investigate the potential in vivo relevance of this inhibition, m phi pHi regulation was examined following incubation with low concentrations of L-arginine that mimic the inflammatory microenvironment, in the presence or absence of lipopolysaccharide (LPS). pHi regulation was evaluated as the ability of thioglycolate-elicited murine peritoneal m phi s to recover from an imposed cytoplasmic acid load. The m phi pHi was measured using a pH-sensitive fluorescent probe. Following incubation for 2 h in the absence of LPS, the pHi recovery rate was equivalent in cells incubated with and without L-arginine. Coincubation with LPS, however, resulted in marked inhibition of pHi recovery at L-arginine concentrations as low as 12.5 microM. The inhibition was not due to LPS alone, since LPS without L-arginine was not inhibitory. Inhibition of pHi recovery was observed at LPS concentrations ranging from 10 ng/ml to 10 micrograms/ml. The L-arginine-dependent inhibition was apparent within 60 min of exposure to LPS, in both freshly harvested cells and cells preincubated for 2 h in the absence of L-arginine and then exposed to both L-arginine and LPS. Under conditions mimicking the in vivo setting, LPS-stimulated L-arginine metabolism impairs m phi pHi regulation. Modulation of pHi by this mechanism may compromise m phi function within the acidic microenvironment of inflammation.

Post-operative radiochemotherapy for gastric cancer: adoption and adaptation.

AIMS: Intergroup study 0116 (INT-0116) showed an 11% absolute improvement in 3-year survival with post-operative radiochemotherapy for gastric cancer, but reported 33% severe acute GI toxicity using conventional simulation with large fields. We adapted the treatment using conformal radiotherapy techniques and assessed toxicity and outcome in 20 consecutive patients. METHODS: A conformal radiotherapy technique previously developed for gastric lymphoma was adapted to treat the target volume defined in INT-0116. The five-field plan used a large anterior field, plus asymmetrically matched upper AP:PA fields and lower lateral fields. Consecutive patients with ECOG PS 0-2 and stage IB-IV non-metastatic gastric cancer were treated with 5-FU (425 mg/m2 daily x 5 days) and leucovorin (20 mg/m2 daily x 5 days) for one cycle prior to and two cycles following concurrent radiation (45 Gy/25 fractions) with identical drug dosages on the first 4 and last 3 days of radiation. Acute toxicity was prospectively recorded weekly using RTOG and NCI common toxicity criteria. Patient charts were reviewed in November 2003 and late toxicity and outcome were recorded. RESULTS: Nineteen of 20 patients completed radiotherapy and 14 completed all chemotherapy cycles. One patient died of neutropenic sepsis. Maximum acute toxicity [grade (number)] was: 5(1), 4(0), 3(4), 2(10), 1(4), 0(1). There were two grade 1 late toxicities. Two-year overall survival is 70% (95% confidence interval: 50-90). CONCLUSIONS: Conformal radiotherapy may improve acute toxicity (25% grade 3 or greater toxicity as compared with 41% reported in INT-0116). Survival is comparable to that achieved in the INT-0116 treatment arm (approximately 60% at 2 years). INT-0116 results can be achieved outside a study setting; however, further efforts to improve treatment efficacy and minimize toxicity are warranted.

A novel role for Plk4 in regulating cell spreading and motility.

Polo family kinase 4 (Plk4) is required for mitotic progression, and is haploinsufficient for tumor suppression and timely hepatocyte polarization in regenerating liver. At the same time, recent evidence suggests that Plk4 expression may have a role in clinical cancer progression, although the mechanisms are not clear. Here we identify a gene expression pattern predictive of reduced motility in Plk4(+/-) murine embryonic fibroblasts (MEFs) and validate this prediction with functional assays of cell spreading, migration and invasion. Increased Plk4 expression enhances cell spreading in Plk4(+/-) MEFs and migration in human embryonic kidney 293T cells, and increases invasion by DLD-1 colon cancer cells. Plk4 depletion impairs invasion of wild-type MEFs and suppresses invasion by MDA-MB231 breast cancer cells. Cytoskeletal reorganization and development of polarity are impaired in Plk4-deficient cells that have been stimulated to migrate. Endogenous Plk4 phosphorylated at the autophosphorylation site S305 localizes to the protrusions of motile cells, coincident with the RhoA GEF Ect2, GTP-bound RhoA and the RhoA effector mDia. Taken together, our findings reveal an unexpected activity of Plk4 that promotes cell migration and may underlie an association between increased Plk4 expression, cancer progression and death from metastasis in solid tumor patients.

Approaches to local salvage of soft tissue sarcoma after primary site failure.

Improvements in pretreatment evaluation and the wider application of specialized multidisciplinary care have substantially reduced the risk of local recurrence for patients with soft tissue sarcomas arising at any site, and the recurrences that are still seen are often those that are most difficult to manage effectively. The management strategy for an isolated local recurrence of soft tissue sarcoma is usually similar to that used for primary disease. With appropriate pretreatment evaluation and salvage therapy that includes a multidisciplinary approach, most patients with local recurrence can expect local disease control and a good functional outcome. The development of effective management of a local recurrence is often a complex problem. The necessary decisions are influenced by the tumor location, disease extent, and previous local therapy. The need for specialized care is stressed. Patient evaluation, management strategies, and expected outcome for various clinical scenarios are discussed.

The local management of soft tissue sarcoma.

Soft tissue sarcomas (STS) are rare tumors arising from the connective tissues. STS can arise at any anatomic site, can demonstrate varied behavior and prognosis, and therefore present a formidable challenge in management. The local treatment of STS demands technical complexity in the application of diagnostic tools, including pathology and imaging, as well as treatment approaches, including surgical ablation and reconstruction, radiotherapy, and, in defined cases, chemotherapy. The understanding of the management of these lesions is profoundly dependent on the multidisciplinary setting, where experience has been gained and skills are available to increase the likelihood of a successful result. Several proven options are available for optimal local management, and the choice of approach depends on the prevailing practice and resource profile of the treating center. With modern approaches, the local control rate can be expected to be at least 90% for extremity lesions, which constitute the most common STS. The experience in other anatomic sites is less favorable as a result of a combination of late diagnosis, technically difficult access sites, and possibly less familiarity with these less common presentations. The disappointing results make it all the more important for patients to be referred to a multidisciplinary setting with experience in sarcoma management to maximize the chance of successful local outcome.

Metastatic colorectal cancer cells induce matrix metalloproteinase release by human monocytes.

Matrix metalloproteinases-2 (MMP-2) and -9 (MMP-9) facilitate tumor invasion and metastasis via basement membrane degradation. In colorectal cancer (CRC) specimens, MMP production is largely stromal in origin, implicating monocytes (M phi s) and fibroblasts. We hypothesize that CRC cells induce stromal cell MMP production. This study examines the differential effect of metastatic and non-metastatic CRC cells on M phi MMP production. The human M phi line THP-1 was co-cultured with either a non-metastatic human CRC cell line (SW620-P) or a metastatic clone (SW620-S5) established by serial cecal transplantation of SW620-P in nude mice. Conditioned medium MMP activity and cellular MMP mRNA expression were assessed by gelatinase zymography and Northern blot analysis, respectively. Neither CRC line released MMP-2 or MMP-9. Isolated THP-1 M phi s produced basal levels of both MMP-2 and MMP-9. The level of MMP-9 activity was increased moderately by co-culture of M phi s with the metastatic SW620-S5 clone, but decreased by the non-metastatic SW620-P cells. MMP-2 activity was greatly augmented by co-culturing M phi s with SW620-S5 cells, but was not affected by SW620-P cells. The stimulatory effect of SW620-S5 cells on MMP-2 secretion was confirmed by Western blot analysis. Both isolated and co-cultured M phi s expressed MMP-2 mRNA while SW620-S5 cells under similar conditions did not, implicating M phi s as the source of increased MMP-2 activity. Since the induction of MMP-2 activity was not associated with a parallel increase in M phi MMP-2 mRNA, the modulation of M phi MMP-2 release appears to be post-transcriptionally regulated. Metastatic CRC cells are distinct from non-metastatic cells in their ability to induce M phi MMP release. This observation emphasizes the role of M phi-derived MMPs in facilitating CRC invasion and metastasis and suggests modulation of stromal cell MMP production by CRC cells in a paracrine fashion.

Modulation of the macrophage respiratory burst by an acidic environment: the critical role of cytoplasmic pH regulation by proton extrusion pumps.

Within the acidic milieu of an abscess or tumor, macrophages must be able to maintain their cytoplasmic pH (pHi) close to the physiologic range to ensure optimal cell function. Our recent studies have demonstrated that a proton-extrusion mechanism with the characteristics of an H+ adenosine triphosphatase mediates pHi recovery in acid-loaded macrophages. These studies were designed to examine the role of these H+ pumps in maintaining cell function in an acidic extracellular environment. Peritoneal macrophages were tested for superoxide production in response to phorbol myristate acetate at either physiologic or acidic extracellular pH (pHo; 7.35 or 6.70, respectively). pHi was measured with the fluorescent dye 2',7'-biscarboxy-ethyl-5(6)-carboxy-fluorescein. Bafilomycin A1, a specific H+ adenosine triphosphatase inhibitor, was used to examine the contribution of the H+ pump to pHi regulation and cell function. At pHo 7.35, bafilomycin A1 had no effect on pHi or phorbol myristate acetate-stimulated superoxide production. However, at pHo 6.70, bafilomycin A1 reduced pHi to 6.61 +/- 0.01 versus 6.79 +/- 0.01 in control cells (p less than 0.001) and caused a concomitant reduction in superoxide production to 4.8 +/- 1.2 versus 13.0 +/- 1.2 nmol/10(6) cells/40 min in control cells (p less than 0.001). To determine whether the observed reduction in superoxide formation was the result of the pHi reduction, superoxide production was measured in cells whose pHi was pharmacologically clamped at various levels according to the K+/nigericin method. Lowering pHi from 6.80 to 6.60 caused a significant reduction in superoxide production from 13.1 +/- 1.8 to 7.5 +/- 0.9 nmol/10(6) cells/40 min (p less than 0.01). Thus H+ extrusion pumps are important to maintenance of macrophage pHi at low pHo, permitting continued superoxide production under these conditions. By keeping pHi close to the physiologic range, these pumps serve to optimize cell function in an acidic extracellular environment.

Bacterial translocation induces procoagulant activity in tissue macrophages. A potential mechanism for end-organ dysfunction.

The ability of bacterial translocation to induce cell-associated procoagulant activity was examined in a rodent model. Intestinal decontamination with streptomycin sulfate and bacitracin followed by oral feeding with a streptomycin-resistant strain of Escherichia coli produced monoassociation of the gastrointestinal tract with this microorganism. Using this model, the rate of bacterial translocation at day 3 increased from 6% (1 of 17) to 90% (28 of 31). Cell-associated procoagulant activity was measured in the mononuclear cell population of mesenteric lymph nodes as well as portal and systemic blood and also in hepatic nonparenchymal cells. In monoassociated animals, the procoagulant activity of mesenteric lymph node mononuclear cells was significantly greater than in control animals at day 3 (210% +/- 28% vs 100% +/- 6%) but not at days 1 or 6. Procoagulant activity of hepatic nonparenchymal cells was elevated in monoassociated animals at days 3 and 6 compared with control animals. Both control and monoassociated animals remained well throughout the experiment. The histologic features of the gastrointestinal tract, mesenteric nodes, and liver did not differ between groups. These studies provide evidence that bacterial translocation, in the absence of external stimuli, is able to induce cell activation at sites remote from the gastrointestinal tract and may therefore contribute to the pathogenesis of multiple organ failure.