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C J Swallow

Publications and source records attributed to C J Swallow.

At least 19 recordsLinked to original sources
PubMed2001

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.

3T3 Cells↗
PubMed2001

Comparative expression of the mitotic regulators SAK and PLK in colorectal cancer.

BACKGROUND: Disruption of normal mechanisms for cell cycle regulation is important in carcinogenesis. SAK and PLK are members of the polo family of serine threonine kinases, which in lower organisms have been shown to be required for the precise regulation of mitosis. Studies of human polo family members have focused on PLK, which has been found to be overexpressed in several tumor types, with the degree of overexpression correlating with adverse clinical outcome. However, PLK expression had not previously been analyzed in colorectal cancer. SAK, a polo family member with unique properties, had not been systematically studied in any tumor type. METHODS: In this study, SAK expression was evaluated in a series of sporadic human colorectal cancer specimens (n = 74) and compared with that of PLK. Expression was assessed by reverse transcription-polymerase chain reaction. RESULTS: In the majority of cases, both SAK and PLK were more highly expressed in tumor tissue than in adjacent normal intestinal mucosa. Levels of SAK and PLK expression in tumor relative to paired normal mucosa correlated directly with patient age and with each other but did not correlate with tumor stage. These results suggest a mechanism for augmented disruption of mitotic regulation in older patients. CONCLUSIONS: The polo family mitotic regulators SAK and PLK are both aberrantly expressed in colorectal cancer. The potential prognostic significance of SAK and PLK expression in colorectal cancer will be evaluated in the future.

Adult↗
PubMed2001

Palliative general surgical procedures.

Two types of procedure may be indicated in incurable patients. The first is palliative, in which the goal of intervention is relief of symptoms. The second type is supportive, where the procedure is a technical intervention done as part of a multidisciplinary treatment plan. The most minimally invasive but effective procedure is chosen. Procedures are categorized by the type of symptom the procedure is intended to relieve. This article emphasizes the principles involved in patient selection and outcome assessment in order to identify areas where more research is needed.

General Surgery↗
PubMed2000

Regulation of human monocyte proMMP-9 production by fetuin, an endogenous TGF-beta antagonist.

Members of the matrix metalloproteinase family of enzymes degrade specific components of the extracellular matrix. MMP-9 is a type IV/V collagenase necessary for normal osteogenesis and is increased in inflammatory and neoplastic conditions. In such destructive diseases as emphysema and arthritis, and in epithelial cancers, MMP-9 is produced by cells of the monocyte lineage. Fetuin, a prominent serum glycoprotein, binds to and inactivates TGF-beta family members and through this mechanism regulates osteogenesis (Binkert et al., 1999, J Biol Chem 274:28514-28520.). We studied the effects of TGF-beta1 and fetuin on proMMP-9 release by the human monocyte line THP-1. Exogenous TGF-beta1 stimulated proMMP-9 release by THP-1 cells, with half-maximal stimulation at approximately 0.01 ng/ml TGF-beta1. Human fetuin (0.5-2 microM) partially inhibited this stimulation. Human fetuin alone stimulated THP-1 monocyte proMMP-9 release, with half maximal stimulation at approximately 0.25 microM fetuin. Neutralizing antibody specific for TGF-beta1 also stimulated proMMP-9 release, suggesting that endogenously-derived TGF-beta1 has an inhibitory effect. In freshly isolated human peripheral blood monocytes, fetuin stimulated proMMP-9 release with a dose-response curve similar to that observed in THP-1 cells. Human fetuin also activated proMMP-9 present in THP-1 conditioned medium. Taken together, these data suggest that under physiological conditions, fetuin facilitates matrix degradation by monocyte-derived MMP-9, both by opposing the autocrine inhibitory effect of endogenous TGF-beta1 on proMMP-9 release, and by activating proMMP-9 in the pericellular milieu. Conversely, fetuin may limit the stimulation of monocyte proMMP-9 release by high levels of exogenous TGF-beta1. Such modulation could prove important under pathological conditions where TGF-beta1 derived from paracrine sources is abundant, such as in epithelial malignancies.

Collagenases↗
PubMed1999

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.

Amputation, Surgical↗
PubMed1999

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.

Amputation, Surgical↗
PubMed1996

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.

Animals↗
PubMed1993

Relative roles of Na+/H+ exchange and vacuolar-type H+ ATPases in regulating cytoplasmic pH and function in murine peritoneal macrophages.

Two distinct mechanisms have been shown to mediate cytoplasmic pH (pHi) recovery in acid-loaded peritoneal macrophages (M phi s): Na+/H+ exchange and H+ extrusion by vacuolar-type (V-type) H+ ATPases. The present studies examined the relative roles of these two systems in maintaining pHi and cell function. Measurements of M phi pHi and superoxide (O2-) production in response to stimulation with 12-O-tetradecanoyl phorbol 13-acetate (TPA) were made at physiological or acidic extracellular pH (pHo) levels. The V-type H+ ATPase inhibitor, bafilomycin A1, and the potent Na+/H+ exchange inhibitor, N-ethyl-N-propylamino amiloride (EPA), were used to examine the contributions of these ion transporters to pHi regulation and cell function. At pHo 7.35, the complementary activities of the Na+/H+ antiport and the V-type H+ ATPase mediate pHi homeostasis. At pHo 6.7, maintenance of pHi depends primarily on H+ ATPase activity: bafilomycin A1 reduced pHi from 6.8 +/- 0.02 in control cells to 6.59 +/- 0.01 (P < 0.01) while EPA was without effect. The functional importance of V-type H+ ATPase-activity in preserving pHi homeostasis at acidic extracellular pH levels was reflected by the impairment of O2- production at pHo 6.70 when H+ ATPase activity was inhibited: bafilomycin A1 reduced O2- production from 13.9 +/- 1.0 to 9.3 +/- 0.6 nmoles/10(6) cells/40 min, in control and bafilomycin A1-treated cells, respectively (P < 0.05), while EPA had no effect. In subsequent studies, pHi was independently manipulated using the ionophore nigericin. Lowering pHi from 6.80 to 6.60 reduced O2- production from 15.3 +/- 1.8 to 9.8 +/- 1.6 nmoles/10(6) cells/40 min (P < 0.05), indicating that the cytoplasmic acidification resulting from inhibition of H+ ATPases at low pHo could account for the associated impairment of O2- production. In a more profoundly acidic environment (pHo 6.35), H+ ATPases remained active in regulating pHi, but could not preserve a sufficiently physiological pHi to support respiratory burst activity. V-type H+ ATPases constitute the dominant mechanism by which the pHi of peritoneal M phi s is maintained in an acidic extracellular environment.

Adenosine Triphosphatases↗
PubMed1992

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.

Animals↗
PubMed1991

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.

Acid-Base Equilibrium↗
PubMed1991

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.

Animals↗
PubMed1991

Regulation of cytoplasmic pH in phagocytic cell function and dysfunction.

To ensure effective antimicrobial or tumouricidal function, phagocytic cells must maintain their cytoplasmic pH (pHi) at a level conductive to optimal intracellular enzyme activity. The mechanisms by which neutrophils and macrophages regulate their cytoplasmic pH include bicarbonate-independent ion transport systems, most notably the Na+/H+ exchanger, and bicarbonate-dependent ion transport systems, which can be subdivided into the cation-independent and Na(+)-dependent forms of chloride/bicarbonate exchange. In addition, macrophages have been shown to recover from intracellular acid loading by means of an ATP-dependent proton extrusion mechanism, which has the characteristics of a vacuolar-type H+ ATPase. In the microenvironment typically associated with abscesses, the low extracellular pH and the presence of short chain fatty acid by-products of bacterial metabolism tend to induce cytoplasmic acid loading. In this setting, the ability of the various pHi regulatory mechanisms to protect pHi may be overcome, leading to cytoplasmic acidification. Several investigators have shown that cytoplasmic acidification impairs the ability of neutrophils to migrate in response to chemotactic stimuli, and also impairs their ability to generate a respiratory burst, thus inhibiting the release of toxic oxygen radicals. This may result in the inability of phagocytes to effect complete abscess resolution.

Abscess↗
PubMed1991

Cytoplasmic pH regulation in monocytes and macrophages: mechanisms and functional implications.

Maintenance of cytoplasmic pH (pHi) within a narrow physiological range is critical to optimal cell function. Monocytes and macrophages (Møs) actively regulate their pHi through three distinct plasma membrane ion transport systems: (1) Na+/H+ exchange; (2) Na(+)-dependent anion exchange; and (3) vacuolar-type H+ ATPases. Alterations in the functional state of monocytes and Møs have been linked to changes in pHi and/or its regulation by these ion transport systems. Differentiation, proliferation, and activation of Møs in response to a variety of agents are associated with increased Na+/H+ exchange. The resultant cytoplasmic alkalinization typically observed in HCO3(-)-free media likely plays a permissive, rather than a triggering, role in mediating Mø response to most of these agents. Prevention of cytoplasmic acidification is essential during Mø activation, when production of metabolic acid increases. This is of particular importance within the in vivo microenvironment of an abscess or tumour, where pHi is further threatened by the low extracellular pH (pHo) which typically prevails. At low pHo, H+ ATPase-mediated H+ extrusion plays a critical role in maintenance of pHi, preserving the ability of Møs to generate a respiratory burst. The requirement for maintenance of pHi within a range conducive to efficient Mø function may explain why Møs have acquired a variety of parallel systems for pHi regulation.

Acid-Base Equilibrium↗
PubMed1990

A vacuolar type H(+)-ATPase regulates cytoplasmic pH in murine macrophages.

An Na(+)- and HCO3(-)-independent mechanism of cytoplasmic pH (pHi) recovery was previously demonstrated in acid-loaded macrophages (Swallow, C. J., Grinstein, S., and Rotstein, O. D. (1988) J. Biol. Chem. 263, 19558-19563). Acid extrusion was found to be ATP-dependent and sensitive to N-ethylmaleimide and N,N'-dicyclohexylcarbodiimide, suggesting involvement of an H(+)-pumping ATPase. In this report, the properties and mode of activation of this putative pump were studied in detail. In acid-loaded cells, pHi recovery, measured using a fluorescent probe, was found to be insensitive to azide or oligomycin, which are inhibitors of F0F1 (mitochondrial) H(+)-ATPases, and to vanadate, an inhibitor of E1E2-type ATPases. Instead, the recovery was sensitive to the vacuolar type H(+)-ATPase inhibitors 7-chloro-4-nitrobenz-2-oxa-1,3-diazole, p-chloromercuribenzenesulfonic acid, and bafilomycin A1. Using the fluorescent probes bisoxonol and 3,3'-dipropylthiodicarbocyanide iodide to measure the membrane potential of intact cells, acid loading of macrophages was shown to result in an N,N'-dicyclohexylcarbodiimide-sensitive hyperpolarization of approximately 15 mV. This hyperpolarization was not inhibited by charybdotoxin, suggesting that it was not due to efflux of K+ through Ca2(+)-activated K+ channels, but may instead be due to electrogenic pumping of protons across the plasma membrane. This was consistent with the partial dependence of the Na(+)- and HCO3(-)-independent pHi recovery on the presence of intracellular Cl-. As in vacuolar membranes, Cl- appears to act as a counterion to H+, preserving electroneutrality and thus facilitating pHi recovery. In acid-loaded urinary epithelial cells, activation of H+ pumping occurs by exocytic insertion of intracellular (vacuolar) H(+)-ATPases into the plasma membrane. In this system, exocytosis is triggered by an associated increase in the cytoplasmic free Ca2+ concentration and is microtubule-dependent. We determined whether an analogous process exists in macrophages. Acid loading of macrophages induced an approximately 120 nM increase in cytoplasmic free Ca2+ concentration due to mobilization of Ca2+ from an intracellular source. However, preventing this increase by preloading macrophages with bis(O-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid did not inhibit the Na+ and HCO3(-)-independent pHi recovery, neither was the recovery inhibited by microtubular disruption using 0.1 mM colchicine. Furthermore, cytoplasmic acid loading did not cause a detectable release of secretory granular, endosomal, or lysosomal contents, suggesting that activation of H+ pumping at the cell surface is not mediated by exocytic fusion of these compartments with the plasma membrane. Taken together, these data suggest that H(+)-ATPases are constitutively present in the macrophage plasma membrane.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1990

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.

Amiloride↗
PubMed1990

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.

Acids↗
PubMed1990

Management of pyogenic liver abscess in the era of computed tomography.

The advent of high-resolution imaging has allowed earlier diagnosis of pyogenic liver abscess. Because radiologically guided percutaneous drainage (PCD) of liver abscesses is controversial, the authors studied 40 patients with liver abscess admitted to the Toronto Hospital between 1982 and 1987 to determine the role of PCD versus operative drainage (OD). The diagnosis of pyogenic liver abscess was made at autopsy (4 patients), at laparotomy (6) or by radiologically guided aspiration of pus (30). Ultrasonography and computed tomography were highly sensitive (85% and 96% respectively) in detecting liver abscess. Of the 36 patients treated for liver abscess all received antibiotics intravenously; 31 also underwent a drainage procedure. Treatment with antibiotics alone was associated with a success rate of 80% and a death rate of 20%. The success rate for those who had PCD was 75% with a death rate of 13%; 2 patients in this group of 16 subsequently required OD for cure. In the 15 patients initially treated with OD, success and death rates were 87% and 13% respectively. For solitary abscesses, success rates wer comparable for PCD and OD (86% and 90% respectively). For unilobar multiple abscesses the success rate was 100% for both PCD and OD, but for bilobar multiple abscesses the rates were only 40% and 67% respectively. Complication rates were similar for both methods of drainage. The authors conclude that pyogenic liver abscess can now be safely and efficaciously managed with a combination of antibiotics and PCD.

Adult↗