Hemipelvectomy hernia: case series and literature review.

PURPOSE: Hemipelvectomy is a major operation in which significant portions of the pelvic girdle and lower extremity are resected. The development of hernia following hemipelvectomy is a complex surgical challenge with limited published guidelines for management. We present our experience with three cases of hernia repair following internal hemipelvectomy and review the previously described ten cases of similar patients. METHODS: A systematic review of the current literature regarding hernias in the setting of hemipelvectomy was performed. A comprehensive search strategy on MEDLINE/PUBMED database searching for the key words of hemipelvectomy and hernia was used. RESULTS: There were 13 reported cases of incisional hernia after hemipelvectomy. The indication for hemipelvectomy was sarcoma in 77% of cases. The median time to presentation for hernia repair was 3 years following initial resection. Mesh repair was used in 77%. Identified risk factors for the development of incisional hernia included chemoradiation, wound infection, multiple operations, and weight gain. There was one event of hernia recurrence with a mean follow-up of 16 months. CONCLUSION: Hernia in the setting of hemipelvectomy is an infrequently reported problem. General principles in management are similar to all hernia repairs and include local approximation of tissues, avoidance of contamination or wound infection, and use of prosthetic mesh when local tissue is inadequate for a tension-free repair.

Contamination of commercial preparations of calmodulin by phospholipase A2.

In the course of studies of the possible regulation of cellular phospholipase A2 activities by calcium and calmodulin, it was observed that some of the commercial preparations of calmodulin contained significant phospholipase A2 activity. Six commercially available calmodulin sources were compared for the presence of contaminating phospholipase A2 activity, relative purity by SDS-gel electrophoresis, and relative biological activity in stimulating calmodulin-deficient phosphodiesterase. One of the commercial calmodulin sources contained a relatively high specific phospholipase A2 activity (1.30 +/- 0.11 nmol [1-14C]arachidonic acid released/mg protein per h) and yielded two major bands in SDS-gel electrophoresis. Two of the calmodulin sources tested were relatively free of phospholipase A2 activity, were quite pure (one band on SDS-gel) and had high biological activity in stimulating calmodulin-deficient phosphodiesterase. Thus, investigators using commercially available preparations of calmodulin should be aware of the contamination of some of these sources by phospholipase A2 activity. These findings may be of importance to investigators considering the role of calmodulin in activating a variety of calcium-dependent enzymes, including phospholipase A2.

Ro 19-3704 directly inhibits immunoglobulin E-dependent mediator release by a mechanism independent of its platelet-activating factor antagonist properties.

Rat basophilic leukemia (RBL 2H3) cells were passively sensitized by exposure to monoclonal anti-trinitrophenol mouse immunoglobulin E (anti-trinitrophenol IgE) (0.5 microgram/ml) and triggered by exposure to a sub-optimal concentration of trinitrophenol ovalbumin conjugate (5 ng/ml). At this concentration, trinitrophenol-ovalbumin increased histamine release from a basal rate of 4.8 +/- 0.5 to 28.5 +/- 4.6% and peptidoleukotrienes from less than 0.1 to 4.2 +/- 1.3 ng/10(6) cells in the activated cells. Ro 19-3704 and Ro 19-1400, platelet activating factor (PAF) antagonists which are structural analogs of PAF, potently inhibited both the IgE-dependent release of histamine (IC50 values of 3.0 and 3.6 microM, respectively) and LT release (IC50 values of 5.0 microM for both compounds) from the cells. These effects appeared to be independent to the ability of the compounds to act as PAF antagonists since PAF on its own had no effect on mediator release, and WEB 2086 and BN 52021, structurally distinct PAF antagonists, were relatively ineffective as inhibitors of mediator release. Ro 19-3704 and Ro 19-1400 were observed to be potent inhibitors of the soluble phospholipase A2 activity in synovial fluid from rheumatoid arthritic patients (IC50 values of 6.5 and 8.4 microM, respectively). In contrast, WEB 2086 and BN 52021 had no effect on this phospholipase A2. Ro 19-3704 significantly inhibited the IgE-dependent formation of inositol phosphates in RBL 2H3 cells (IC50 value of 7.0 microM). These data suggest that the mediator release inhibitory action of these compounds may be related to the ability of these compounds to inhibit phospholipase A2 and/or phospholipase C.

Retinoids inhibit phospholipase A2 in human synovial fluid and arachidonic acid release from rat peritoneal macrophages.

Retinoids have demonstrated antiinflammatory activity in certain animal models and human disease states. The mechanism by which retinoids elicit this activity is unknown. Some retinoids are known to inhibit arachidonic acid (AA) release and metabolism in intact cells in vitro. Retinoids may exert their antiinflammatory effects by inhibiting phospholipase A2 (PLA2) and the resultant production of inflammatory AA metabolites. Retinoids were evaluated in vitro as inhibitors of the PLA2 activity in human synovial fluid (HSF-PLA2). Of the naturally occurring, nonaromatic retinoids tested, all-trans-retinal, all-trans-retinoic acid (all-trans-RA) and 13-cis-RA were the most potent inhibitors (IC50 S 6-15 microM), whereas all-trans-retinol was much less potent. Of the synthetic aromatic retinoids and arotinoids examined, the free carboxylic, sulfonic, and sulfinic acid forms were more than 15-fold more potent inhibitors of HSF-PLA2 than their corresponding ethyl esters. These retinoids also were evaluated as inhibitors of calcium ionophore A23187-induced AA release from rat peritoneal macrophages. All-trans-RA and 13-cis-RA were potent inhibitors of AA release from these cells (IC50 S 4 microM), while the other natural retinoids were inactive. Of the aromatic retinoids and arotinoids tested, the free acid forms (IC50 S 2-6 microM) were 5- to 21-fold more potent inhibitors of AA release from the macrophages than their corresponding ethyl esters. The potencies of the arotinoids as inhibitors of HSF-PLA2 appeared to correlate with their potencies as inhibitors of AA release from A23187-stimulated rat peritoneal macrophages. These data support the hypothesis that one possible mechanism for the known antiinflammatory activity of some retinoids may be by inhibition of phospholipase A2.

Antiflammin-2 (HDMNKVLDL) does not inhibit phospholipase A2 activities.

A basic nonapeptide P2 (antiflammin-2, HDMNKVLDL) which is identical to a portion of the amino acid sequence (residues 246-254) of lipocortin I, has been described to have antiinflammatory activity in a rat paw edema model (Nature 335: 726-730 [1988]). P2 (0.05 microM) was also reported to inhibit porcine pancreatic phospholipase A2 (PLA2). The effect of synthetic P2 (98% pure) on PLA2 was evaluated in two assay systems. Using porcine pancreatic PLA2 and phosphatidylcholine/deoxycholate mixed micellar substrate, P2 (0.005-50 microM) had no effect on PLA2 activity, even in the presence of 2-mercaptoethanol to prevent peptide oxidation. In another assay, using human synovial fluid PLA2 as the enzyme and [14C]-oleate-labelled E. coli substrate, P2 (0.005-50 microM) had no significant effect on PLA2 activity. A reported PLA2 inhibitor, manoalide, was a potent inhibitor of PLA2 in both assay systems. On the basis of these results, we conclude that P2 is devoid of PLA2 inhibitory activity.

Secretory phospholipase A2 inhibitors and calmodulin antagonists as inhibitors of cytosolic phospholipase A2.

Human cytosolic phospholipase A2 (cPLA2, 85 kDa) appears to be pharmacologically distinct from human secretory phospholipase A2 (sPLA2, 14 kDa). Marine natural products and PLA2 substrate and product analogs were potent inhibitors of human recombinant sPLA2 (r-sPLA2), whereas these compounds stimulated, weakly inhibited, or had no effect on cPLA2 activity from the human monocytic cell line U937. In contrast, within a series of seven reported calmodulin (CaM) antagonists tested, significant correlations among the rank order of potencies of these compounds as inhibitors of cPLA2, r-sPLA2, and a CaM-dependent phosphodiesterase were observed. The correlated inhibitory effects of the hydrophobic CaM antagonists on cPLA2 and sPLA2 may reflect a common feature (possibly a hydrophobic domain) shared by these two types of enzymes.

Influence of dietary vitamin E on prostaglandin biosynthesis in rat blood.

A vitamin E (alpha-tocopherol) deficient diet stimulated prostaglandin biosynthesis in coagulating rat blood. Prostaglandins were extracted from serum, purified and bioassayed. The identity of prostaglandin E2 was confirmed by gas chromatography-mass spectrometry. Withholding vitamin E from the diet caused a marked increase in PGE2 and a lesser increase in PGF2alpha production in serum. In rats maintained on diets containing different concentrations of vitamin E, serum concentrations of PGE2 and PGF2alpha were inversely related to serum concentrations of alpha-tocopherol. These data suggest that in vitro alpha-tocopherol inhibits the endogenous conversion of arachidonic acid into PGE2 and PGF2alpha. The possibility that alpha-tocopherol may inhibit the formation of endoperoxide intermediates of PGE2 and PGF2alpha biosynthesis and subsequent induction of platelet aggregation is discussed.

In vitro studies on the mechanism of action of a new antiallergic, Ro 21-7634.

The effects of Ro 21-7634 and disodium cromoglycate (cromoglycate) on the in vitro release of mediators of anaphylaxis from rat peritoneal cells and guinea pig lung tissue were compared. Ro 21-7634 was 25 fold more potent than cromoglycate as an inhibitor of antigen-induced histamine release from passively sensitized (IgE) rat peritoneal cells. Ro 21-7634 was also the more potent inhibitor of both compound 48/80- and concanavalin A-induced histamine release from rat peritoneal cells. The two drugs shared the common properties of producing the same maximal level of inhibition in each of the above releasing systems and exhibiting a time and concentration dependent loss of inhibitory activity when added to the cells prior to the releasing agent. Neither drug inhibited ionophore A23187-or ionophore X537A-induced histamine release from these cells. Ro 21-7634 inhibited antigen-induced (IgG1) histamine and SRS-A release from actively sensitized guinea pig lung fragments, whereas cromoglycate did not. The results indicate that Ro 21-7634 and cromoglycate act through a common mechanism to inhibit allergic mediator release and that Ro 21-7634 is the more potent inhibitor.

Interleukin-1 beta stimulates cytosolic phospholipase A2 in rheumatoid synovial fibroblasts.

Phospholipase A2 (PLA2) activities in rheumatoid synovial fibroblasts (RSF) stimulated with interleukin-1 beta (IL-1 beta) were investigated. RSF incubated in the presence of IL-1 beta (120 pg/ml) for 18 h secreted 35 fold more PGE2 than did those incubated without IL-1 beta. IL-1 beta treatment did not increase the level of secretory PLA2 (sPLA2) activity or sPLA2 protein in the conditioned medium or subcellular fractions of lysed RSF. In contrast, the cell-associated PLA2 activity increased 3 to 4 fold in IL-1 beta stimulated RSF when compared with the control. The IL-1 beta stimulated, cell-associated PLA2 required submicromolar concentrations of calcium for activity, a characteristic consistent with the calcium sensitivity of cytosolic PLA2 (cPLA2) activity reported in other cell types, such as U937 cells. These findings demonstrate that an elevation in a cytosolic PLA2, rather than a sPLA2, is associated with increased PGE2 production in IL-1 beta stimulated RSF.

Comparative study of natural and synthetic retinoids as inhibitors of arachidonic acid release and metabolism in rat peritoneal macrophages.

The effect of several natural and synthetic retinoids on the release and metabolism of arachidonic acid (20:4) in rat peritoneal macrophages (M phi), stimulated in vitro by either Ca2+ ionophore A23187 (A23187), opsonized zymosan (OZ) or 12-O-tetradecanoylphorbol-13-acetate (TPA), was investigated. With the exception of Ro 10-1670, the retinoids containing a free carboxylic acid group [i.e., all-trans-retinoic acid (all-trans-RA), 13-cis-RA, Ro 13-7652, Ro 12-7310 and Ro 13-7410] inhibited 20:4 metabolite formation in A23187- and OZ-stimulated Mø at 1-33 microM. However, only all-trans-RA, Ro 12-7310 and Ro 13-7410 inhibited the formation of 20:4 metabolites in TPA-stimulated Mø. These data suggest that part of the therapeutic effect of retinoids in inflammatory, hyperproliferative dermatologic conditions might be attributed to reduced 20:4 metabolite production.

Ro 22-3747: a new antiallergic agent for the treatment of immediate hypersensitivity diseases.

Ro 22-3747 was orally active in two animal models of immediate hypersensitivity diseases mediated by immunoglobulin E: the rat passive cutaneous anaphylaxis test (ID50 of 0.65 mg/kg) and a model in which anaphylactic bronchospasm was studied in passively sensitized rats (ID50 of 0.022 mg/kg). In the latter model system Ro 22-3747 was also found efficacious by the aerosol route (Ro 22-3747 was 23-fold more potent than disodium cromoglycate by this route of administration). Like disodium cromoglycate (cromoglycate), Ro 22-3747 appears to act in these in vivo models by inhibition of allergic mediator release because it was a potent inhibitor of antigen-induced histamine release from passively sensitized rat peritoneal cells in vitro (IC50 values of 0.25 and 1.5 microM for Ro 22-3747 and cromoglycate, respectively) and did not exhibit end organ antagonism to histamine, serotonin or slow reacting substance of anaphylaxis. The mechanism by which Ro 22-3747 inhibits mediator release does not appear to involve inhibition of delta 5-lipoxygenase, phospholipase A2 or thromboxane synthase. Cromoglycate and Ro 22-3747 appear to have some similarities with regard to their mechanism of action, as they both exhibit a time-dependent loss of inhibitory activity when preincubated with peritoneal cells in vitro before antigen challenge. In addition, pretreatment with one prevented the subsequent inhibition of histamine release by the other. Unlike cromoglycate, however, Ro 22-3747 (10(-5) to 10(-3) M) also inhibited the release of histamine (3-59%), slow reacting substance of anaphylaxis (12-49%) and thromboxane (0-55%) from antigen-challenged (immunoglobulin G1-mediated) guinea-pig lung fragments.(ABSTRACT TRUNCATED AT 250 WORDS)

Interleukin-1 beta induces cytosolic PLA2 in parallel with prostaglandin E2 in rheumatoid synovial fibroblasts.

We investigated the temporal relationship between the increase in enzymatic activity and protein of a high molecular weight (100 kDa), cytosolic PLA2 (cPLA2) in interleukin-1 beta (IL-1 beta)-treated rheumatoid synovial fibroblasts (RSF). Both of these responses increased according to a similar time-course which correlates with PGE2 production by these cells. In contrast, 14 kDa, secreted PLA2 (sPLA2), which was also produced by RSF, was not affected by IL-1 beta treatment. These findings support that an augmentation of CPLA2 activity, caused by an induction of cPLA2 protein, rather than sPLA2, is temporally associated with increased PGE2 production in IL-1 beta-treated RSF.

Analogs of arachidonic acid methylated at C-7 and C-10 as inhibitors of leukotriene biosynthesis.

The syntheses and biological activity of (all Z)-7,7-dimethyl-5,8,11,14- eicosatetraenoic acid, (all Z)-7,7,-dimethyl-5,8,11-eicosatrienoic acid, (Z,Z)-7,7-dimethyl-5,8-eicosadienoic acid, (all Z)-10,10-dimethyl-5,8,11,14-eicosatetraenoic acid, (all Z)-10,10-dimethyl-5,8,11-eicosatrienoic acid, and rac.-(Z,Z)-15-hydroxy-7,7-dimethyl-5,8-eicosadienoic acid are described. These arachidonic acid analogs are all inhibitors of ionophore-induced SRS-A biosynthesis in rat peritoneal cells. Their mode of action may involve inhibition of phospholipase A2 rather than delta 5-lipoxygenase. These compounds failed to exhibit significant activity in an in vivo model designed to detect inhibitors of antigen-induced, leukotriene-mediated bronchoconstriction in sensitized guinea pigs.

Interleukin-1 beta induces cytosolic phospholipase A2 and prostaglandin H synthase in rheumatoid synovial fibroblasts. Evidence for their roles in the production of prostaglandin E2.

OBJECTIVE: In order to investigate potential regulatory mechanisms for the increased production of prostaglandin E2 (PGE2) in interleukin-1 beta (IL-1 beta)-stimulated rheumatoid synovial fibroblasts (RSF), this study examined the induction of phospholipase A2 (PLA2) and prostaglandin H synthase (PGHS) enzymes and the correlation of these events with PGE2 production in IL-1 beta-stimulated RSF. METHODS: Protein and messenger RNA (mRNA) levels of cytosolic PLA2 (cPLA2) and PGHS-2 enzymes in IL-1 beta-stimulated RSF were measured by Western and Northern blotting, respectively, using specific antisera and complementary DNA probes. Enzymatic activity of cPLA2 was determined in cell-free reaction mixtures utilizing mixed micelles of 14C-phosphatidylcholine and Triton X-100 as the substrate. PGE2 levels were quantitated using a commercial enzyme immunoassay kit. RESULTS: Incubation of RSF with IL-1 beta increased the mRNA and protein levels for the high molecular weight cPLA2 as well as for the mitogen/growth factor-responsive PGHS (PGHS-2). The IL-1 receptor antagonist completely abolished the induction of these two enzymes and the stimulation of PGE2 production by IL-1 beta in RSF. In contrast, levels of the other known forms of these enzymes, i.e., the 14-kd secretory group II PLA2 (sPLA2) and the constitutive form of PGHS (PGHS-1), were unaffected by IL-1 beta treatment. CONCLUSION: These are the first data to demonstrate the coordinate induction by IL-1 of cPLA2 and PGHS-2 in RSF. The time-course for the induction of these enzymes suggests that their increase contributes to the increased production of PGE2 in IL-1-treated RSF, and may help explain the capacity of RSF to produce large amounts of PGE2.