Comparison of unilateral and bilateral spinal anesthesia with 2% hyperbaric prilocaine in day-case inguinal herniorrhaphy: a randomized controlled trial

BACKGROUND

Hyperbaric 2% prilocaine produces a faster onset and shorter duration of spinal anesthesia than a plain solution. The anesthetic profile could be improved by restricting the block to the operative side. We compared unilateral versus conventional bilateral spinal anesthesia with hyperbaric 2% prilocaine in day-case patients undergoing unilateral inguinal herniorrhaphy.

METHODS

Eighty patients were randomly assigned to receive either conventional bilateral (N.=40) or unilateral (N.=40) spinal anesthesia with 50 mg hyperbaric prilocaine 2%. In the unilateral group, lateral decubitus was maintained for 10 minutes. Sensory and motor block courses, time to first micturition, and side effects were recorded.

RESULTS

On the operated side, the highest sensory block was T8 (T12-T2) in the unilateral and T9 (T11-T4) in the bilateral group (P=0.0328); the time to motor (115 ± 26 min in the unilateral and 108 ± 24 min in the bilateral groups, P=0.2350) and sensory (156 ± 30 min in the unilateral and 158 ± 26 min in the bilateral groups, P=0.7550) block resolution was similar in both groups. On the non-operated side, the unilateral group had a faster motor (64 ± 48, P<0.001) and sensory (120 ± 47, P<0.001) time to block resolution than the conventional group. Restricted unilateral motor and sensory block was achieved in 30% and 12.5% of patients, respectively. Time to voiding was shorter in the unilateral than in the conventional group (220 ± 47 vs. 249 ± 51 min, respectively, P=0.0104). There were no significant differences in adequacy for surgery and side effects between the groups.

CONCLUSION

In day-case inguinal herniorrhaphy, attempting unilateral spinal anesthesia with 50 mg hyperbaric 2% prilocaine produced faster time to voiding.

trans-Arachidonic acids induce a heme oxygenase-dependent vasorelaxation of cerebral microvasculature

Nitrative stress is an important regulator of vascular tone. We have recently described that trans-arachidonic acids (TAA) are major products of NO(2)(.)-mediated isomerization of arachidonic acid in cell membranes and that nitrative stress increases TAA levels leading to neural microvascular degeneration. In the present study, we explored whether TAA exert acute effects on neuromicrovascular tone and investigated potential mechanisms thereof. TAA induced an endothelium-dependent vasorelaxation of rat brain pial microvasculature. This vasorelaxation was independent of nitric oxide, prostanoids, lipoxygenase products, and CYP(450) metabolite trans-hydroxyeicosatetraenoic acids. However, inhibition of heme oxygenase (using zinc protoporphyrin IX) and of dependent soluble guanylate cyclase (sGC; using ODQ) significantly diminished (by approximately 70%) the TAA-induced vasorelaxation. Consistent with these findings, TAA stimulated heme oxygenase (HO)-2-dependent bilirubin (using siRNA HO-2) and cGMP formation, and the HO product carbon monoxide (using CO-releasing CORM-2) reproduced the sGC-dependent cGMP formation and vasorelaxation. Further exploration revealed that TAA-induced vasorelaxation and bilirubin formation (HO activation) were nearly abrogated by large-conductance calcium-dependent potassium channels (BK(Ca)) (using TEA and iberiotoxin). Opening of BK(Ca) with the selective activator NS1619 induced a concentration-dependent vasorelaxation, which was inhibited by HO and sGC inhibitors. Coimmunoprecipitation suggested a molecular complex interaction between BK(Ca) and HO-2 (but not HO-1). Collectively, these findings identify new properties of TAA, specifically cerebral vasorelaxation through interactive activation of BK(Ca) with HO-2 and, in turn, sGC. Our findings provide new insights into the characterization of nitrative stress-derived TAA products, by showing they can act as acute mediators of nitrative stress on neurovascular tone.

G-protein-coupled receptors signalling at the cell nucleus: an emerging paradigm

G-protein-coupled receptors (GPCRs) comprise a wide family of monomeric heptahelical glycoproteins that recognize a broad array of extracellular mediators including cationic amines, lipids, peptides, proteins, and sensory agents. Thus far, much attention has been given towards the comprehension of intracellular signaling mechanisms activated by cell membrane GPCRs, which convert extracellular hormonal stimuli into acute, non-genomic (e.g., hormone secretion, muscle contraction, and cell metabolism) and delayed, genomic biological responses (e.g., cell division, proliferation, and apoptosis). However, with respect to the latter response, there is compelling evidence for a novel intracrine mode of genomic regulation by GPCRs that implies either the endocytosis and nuclear translocation of peripheral-liganded GPCR and (or) the activation of nuclearly located GPCR by endogenously produced, nonsecreted ligands. A noteworthy example of the last scenario is given by heptahelical receptors that are activated by bioactive lipoids (e.g., PGE(2) and PAF), many of which may be formed from bilayer membranes including those of the nucleus. The experimental evidence for the nuclear localization and signalling of GPCRs will be reviewed. We will also discuss possible molecular mechanisms responsible for the atypical compartmentalization of GPCRs at the cell nucleus, along with their role in gene expression.

Intracrine signaling through lipid mediators and their cognate nuclear G-protein-coupled receptors: a paradigm based on PGE2, PAF, and LPA1 receptors

Prostaglandins (PGs), platelet-activating factor (PAF), and lysophosphatidic acid (LPA) are ubiquitous lipid mediators that play important roles in inflammation, cardiovascular homeostasis, and immunity and are also known to modulate gene expression of specific pro-inflammatory genes. The mechanism of action of these lipids is thought to be primarily dependent on their specific plasma membrane receptors belonging to the superfamily of G-protein-coupled receptors (GPCR). Increasing evidence suggests the existence of a functional intracellular GPCR population. It has been proposed that immediate effects are mediated via cell surface receptors whereas long-term responses are dependent upon intracellular receptor effects. Indeed, receptors for PAF, LPA, and PGE(2) (specifically EP(1), EP(3), and EP(4)) localize at the cell nucleus of cerebral microvascular endothelial cells of newborn pigs, rat hepatocytes, and cells overexpressing each receptor. Stimulation of isolated nuclei with these lipids reveals biological functions including transcriptional regulation of major genes, namely c-fos, cylooxygenase-2, and endothelial as well as inducible nitric oxide synthase. In the present review, we shall focus on the nuclear localization and signaling of GPCRs recognizing PGE(2), PAF, and LPA phospholipids as ligands. Mechanisms on how nuclear PGE2, PAF, and LPA receptors activate gene transcription and nuclear localization pathways are presented. Intracrine signaling for lipid mediators uncover novel pathways to elicit their effects; accordingly, intracellular GPCRs constitute a distinctive mode of action for gene regulation.

Proangiogenic Effects of Protease-Activated Receptor 2 Are Tumor Necrosis Factor-α and Consecutively Tie2 Dependent

Objective— Angiogenesis is essential physiologically in growth and pathologically in tumor development, chronic inflammatory disorders, and proliferative retinopathies. Activation of protease-activated receptor 2 (PAR2) leads to a proangiogenic response, but its mechanisms have yet to be specifically described. Here, we investigated the mode of action of PAR2 in retinal angiogenesis.

Methods and Results— PAR2-activating peptide, SLIGRL, increased retinal angiogenesis associated with an induction of vascular endothelial growth factor and angiopoetin-2 and most notably tie2 in the retina in vivo as well as in cultured neuroretinal endothelial cells. SLIGRL also induced release of the proinflammatory and angiogenic mediator tumor necrosis factor-α (TNF-α) via the MEK/extracellular signal-regulated kinase (ERK) (MEK/ERK) pathway in these endothelial cells. TNF-α, in turn, elicited tie2 expression by activating the MEK/ERK pathway. PAR2-evoked tie2 expression, endothelium proliferation (in vitro), and retinal neovascularization (in vivo) were abrogated by selective TNF-α blockers (neutralizing antibody infliximab and soluble TNF-α receptor-Fc fusion protein etanercept) as well as the MEK inhibitor PD98059.

Conclusion— The proangiogenic properties of PAR2 are intertwined with its proinflammatory effects, such that in retinal vasculature, they depend on TNF-α and subsequent induction of tie2 via the MEK/ERK pathway.

Human TDE1, a TDE1/TMS family member, inhibits apoptosis in vitro and stimulates in vivo tumorigenesis

We have previously described hTDE1, the human homologue of the recently described TDE1/TMS family of proteins whose members have been identified in several species. Although a defined biochemical activity has yet to be assigned to TDE1/TMS family members, previous results point to the overexpression of family members in tumor cell lines or tissues. To define whether hTDE1 may directly impact on neoplastic transformation, we derived and characterized stable Rat-1 transfectants that constitutively express hTDE1 at the plasma membrane. Expression of hTDE1 in Rat-1 transfectants had a significant effect on cell contact inhibition in vitro as judged by a focus formation assay. In addition, by monitoring caspase-3 activity and Hoechst staining, we determined that hTDE1 overexpression partially protects cells from serum starvation- and etoposide-induced apoptosis. Finally, hTDE1 Rat-1-expressing clones accelerated the formation of tumors in a nude mouse assay. Our results suggest that hTDE1 contributes directly to oncogenesis in vivo that may in part be explained by its effect on apoptosis in vitro.

Microarray analysis of gene expression mirrors the biology of an ovarian cancer model

We have previously described an ovarian cancer model based on four independent spontaneously immortalized epithelial ovarian cancer cell lines (TOV-21G, TOV-81D, TOV-112D and OV-90) from patients who were never exposed to chemotherapy or radiation therapy. These cell lines are particularly interesting since they retain characteristics of the original epithelial ovarian cancers (EOC) from which they were derived. Here we report the characterization of this model system using high-density DNA microarrays in order to assess gene expression. Expression profiles were generated from total RNAs extracted from the four EOC cell lines. For comparison, expression profiling is also provided for a primary culture of normal ovarian surface epithelium (NOV-31) and a fresh EOC sample (TOV-578G). Comparison of expression profiles revealed patterns of expression that distinguish NOV-31 from that of all tumor derived samples. The expression pattern of TOV-81D, an EOC cell line that was derived from a patient with indolent disease, most closely resembles NOV-31 while profiles of samples derived from patients with more aggressive disease (TOV-21G, OV-90, TOV-112D and TOV-578G) showed more divergent patterns of expression. The microarray analysis (http://genome.mcgill.ca) results confirm the usefulness of an ovarian cancer model based on the characterization of these EOC cell lines.

Polyomavirus large T-antigen protects mouse cells from Fas-, TNF-alpha- and taxol-induced apoptosis

Polyomavirus large T-antigen (PyLT-Ag), a nucleophosphoprotein essential for regulating viral gene expression, modulates the cell cycle by binding to the Rb tumor suppressor gene product. PyLT-Ag/Rb binding is essential for in vitro immortalization. However, the effect of PyLT-Ag on apoptosis has not been extensively studied. We have previously reported that FasR agonist antibodies (FasR(Ab)) treatment of Sertoli cells derived from transgenic mice expressing PyLT-Ag induces the growth arrest of these cells without concomitant apoptosis. Here we show that stable expression of PyLT-Ag in murine Sertoli TM4 and hybridoma NSO cell lines confers protection from FasR(Ab)-induced apoptosis. The protection was maintained up to 48 h when cells were grown continuously in the presence of FasR(Ab). Removal of the death stimulus after 24 h exposure was sufficient to allow full recovery of the PyLT-Ag expressing cells. The protective effect conferred by PyLT-Ag was associated with a delay in the sequential activation of caspase-8 and -3 after FasR(Ab) treatment. PyLT-Ag co-precipitated following immunoprecipitation of caspase-8 or FADD, both components of the DISC. Based on these results we suggest that PyLT-Ag directly impedes the recruitment or activation of caspase-8 by the FasR. PyLT-Ag expression in TM4 cells was also associated with protection from TNF-alpha- and taxol-induced apoptosis. In contrast, PyLT-Ag expression was not sufficient to confer protection from captothecin-induced apoptosis. Taken together, these results indicate that PyLT-Ag can be a potent inhibitor of Fas(R)(Ab)-, TNF-alpha- and taxol-induced apoptosis.

The human TDE gene homologue: localization to 20q13.1-13.3 and variable expression in human tumor cell lines and tissue

Expression of the mouse testicular tumor differentially expressed (TDE) gene is increased in testicular tumors as well as in testicular tumor cell lines derived from transgenic mice carrying the polyomavirus large-T antigen under the control of the metallothionein-1 promoter. To determine whether the TDE gene has a role in the development of human cancers, we used the mouse TDE cDNA sequence to screen a human placental cDNA library. The human TDE cDNA homologue coded for a protein that was 78% homologous to the mouse TDE amino acid sequence. Like the mouse TDE protein, the human TDE protein had several predicted hydrophobic alpha-helices characteristic of transmembrane proteins. The human TDE gene was expressed in all cell lines and tissues examined. Four mRNA species were observed in placenta, where we identified an alternate splicing pattern and the use of two different polyadenylation sites. Using fluoresence in situ hybridization analysis, we localized the human TDE gene to the q13.1-13.3 region of chromosome 20, a region known to be amplified in several types of human cancers. We then observed, by northern blot analysis, that human TDE expression was increased in three of five lung tumors examined.

alpha 1-Antitrypsin (AAT) deficiency and ANCA-positive systemic vasculitis: genetic and clinical implications

A high incidence of alpha 1-antitrypsin (AAT) deficiency has been reported in patients with C-ANCA systemic vasculitis in association with antibodies against proteinase-3 (PR3). To clarify the role of AAT deficiency in the acute vasculitic process as well as in progression of the disease, we studied 84 patients with either C-ANCA or P-ANCA vasculitis with special reference to: (a) the AAT gene, (b) the phenotypic (Pi) variants and (c) the serum levels during both acute illness and remission. The PiZ gene was found in six patients (8% vs. 1.5% controls) irrespective of the type of autoantibodies (C-ANCA vs. P-ANCA). All PiZ patients displayed the ability to raise their AAT serum levels up to the normal range during acute illness. In contrast, 24 patients with the PiM phenotype presented low AAT serum levels during acute illness. In all these patients, the AAT levels returned to normal values during the remission. Low AAT levels were associated with low levels of C-reactive protein (PCR) (P < 0.001), with a less severe renal involvement or a minor risk of death, and, in one tested patient, with a novel point mutation (TCGA-->TCAA) at the enhancer-promoter region of the AAT gene. Low AAT serum levels did not correlate with either type/titre of autoantibody or distribution/severity of the vasculitis process. In the case-control study, high AAT levels emerged as a major determinant of progression towards end-stage renal failure [odds ratio 3 (95% CI 1.1-8.4)]. These results indicate: (a) a high incidence of the PiZ gene of AAT in systemic vasculitis irrespective of the type of autoantibodies; (b) a novel form of AAT deficiency associated with the normal PiM phenotype becoming manifest only during acute illness; (c) dysregulation of the acute-phase response affecting selectively AAT or both AAT and PCR; (d) correlation between low plasma levels of AAT and less severe renal involvement or risk of death.

The human skeletal muscle glycogenin gene: cDNA, tissue expression and chromosomal localization

Glycogen synthesis is impaired in first degree relatives of subjects with non-insulin-dependent diabetes mellitus and genes relevant to this metabolic pathway are considered reasonable candidates in the pathogenesis of the disease. In skeletal muscle the de novo synthesis of glycogen in primed by an enzyme named glycogenin. We have cloned the glycogenin cDNA from human skeletal muscle mRNA: human glucogenin is a 333 amino acid protein exhibiting 93% identity with rabbit glycogenin. A single transcript of about 2.4 kb, prominent in skeletal muscle, was detected by Northern blot analysis. In situ hybridization unequivocally located the human glycogenin gene to chromosome 3q25.1. Furthermore, we mapped two intronless glycogenin-related sequences to human chromosomes 12 and 13.

Cloning and characterization of a new human Xq13 gene, encoding a putative helicase

We describe the cloning and characterization of a new human Xq13 gene (XH2), extending over a 220 kb genomic stretch between MNK and DXS56. The gene, which undergoes X-inactivation, contains a 4 kb open reading frame and encodes a putative NTP-binding nuclear protein homologous to several members of the helicase II superfamily. The murine homologue maps to the syntenic genetic interval, between Pgk1 and Xist. In situ hybridization studies in mouse reveal precocious, widespread expression of the murine homologue of XH2 at early stages of embryogenesis, and more restricted expression during late developmental stages and at birth. XH2 is a new member of an expanding family of proven and putative helicases, sharing six conserved, collinear domains. In particular, the XH2 protein shows homology with yeast RAD54. Type II helicases have been implicated in nucleotide excision repair and the initiation of transcription. This new gene, represents a potential candidate for several genetic disorders mapped to human Xq13.