Comparing the preventive effect of midazolam and midazolam-dexamethasone on postoperative nausea and vomiting in elective middle ear surgery

Background:

Nausea and vomiting are common postoperative complications with incidence of 20–80% depends on the surgery type, anesthetic drugs, age, sex, etc. This complication may lead to patient discomfort, intraocular, and intracerebral pressures increase, sutures rupture, esophageal injury, and rarely death. Many studies reported that midazolam and dexamethasone alone can decrease postoperative nausea and vomiting (PONV), but their combination has never been studied yet. The aim of this study was to compare the effect of midazolam and midazolam-dexamethasone on PONV after middle ear surgery.

Materials and Methods:

66 ASA I and II patients aged 15–65 year scheduled for elective middle ear surgery under general anesthesia randomly divided into two groups. Immediately after induction of the anesthesia group one (M) received midazolam 0.075 mg/kg and group two (M+D) received combination of midazolam (0.075 mg/kg) plus dexamethasone (0.05 mg/kg). Then the severity of nausea was measured by visual analog scales 0–10 (VAS) in recovery room at 6, 12, and 24 h after surgery. Metoclopramid (0.1 mg/kg) was administrated I.V. slowly if nausea score was above 3 or patient had vomiting. The postoperative need for antiemetics and the duration of stay in recovery room were recorded. Values of P<0.05 were considered statistically significant.

Results:

There were no significant differences in age, gender, and weight between the two groups. There was no significant difference in the mean nausea scores between two groups except after 12 h postoperatively (1.39 ± 3.19 in M group vs. 0.42 ± 1.71 in M+D group). The mean vomiting frequency was significantly less in midazolam-dexamethasone group in the recovery room (0.9 ± 0.29 vs. 0 ± 0) and at 6–12 h (1.09 ± 2.41 vs. 0.3 ± 0.8), and 12–24 h (0.42 ± 1.32 vs. 0.03 ± 0.17) postoperatively. During the first 24 h postoperatively, the metoclopramid consumption was significantly less in combination therapy (6.48 ± 9.54) than in the midazolam group (12.9 ± 23.44) (Value<0.5).

Conclusion:

The combination of midazolam-dexametazone is more effective than midazolam alone in prevention of postoperative vomiting after middle ear surgery. Therefore, we recommend combination therapy for patients who are prone to PONV.

Birc1e is the gene within the Lgn1 locus associated with resistance to Legionella pneumophila

In inbred mouse strains, permissiveness to intracellular replication of Legionella pneumophila is controlled by a single locus (Lgn1), which maps to a region within distal Chromosome 13 that contains multiple copies of the gene baculoviral IAP repeat-containing 1 (Birc1, also called Naip; refs. 1-3). Genomic BAC clones from the critical interval were transferred into transgenic mice to functionally complement the Lgn1-associated susceptibility of A/J mice to L. pneumophila. Here we report that two independent BAC clones that rescue susceptibility have an overlapping region of 56 kb in which the entire Lgn1 transcript must lie. The only known full-length transcript coded in this region is Birc1e (also called Naip5).

The hippocampal neurons of neuronal apoptosis inhibitory protein 1 (NAIP1)-deleted mice display increased vulnerability to kainic acid-induced injury

The neuronal apoptosis inhibitory protein (NAIP) is a member of a novel family of inhibitor of apoptosis (IAP) proteins. The IAP genes are highly conserved from baculovirus to metazoans and suppress apoptosis induced by a variety of triggers both in vitro and in vivo. Here we describe the generation and characterization of mice with the targeted deletion of NAIP1. We demonstrate that the NAIP1-deleted mice develop normally. However, the survival of pyramidal neurons in the hippocampus after kainic acid-induced limbic seizures is greatly reduced in the NAIP1 knock-out animals. Thus, although NAIP1 is not necessary for normal development of murine central nervous system, the endogenous NAIP1 is required for neuronal survival in pathological conditions.

The neuronal apoptosis inhibitory protein (Naip) is expressed in macrophages and is modulated after phagocytosis and during intracellular infection with Legionella pneumophila

Legionella pneumophila is an intracellular pathogen that causes Legionnaires' disease in humans. Inbred mouse strains are uniformly resistant to L. pneumophila infection with the notable exception of A/J, where the chromosome 13 locus Lgn1 renders A/J macrophages permissive to L. pneumophila replication. The mouse Lgn1 region is syntenic with the spinal muscular atrophy (SMA) locus on human chromosome 5 and includes several copies of the neuronal apoptosis inhibitory protein (Naip) gene. We have analyzed a possible link among Lgn1, Naip, and macrophage function. RNA expression studies show that Naip (mostly copy 2) mRNA transcripts are expressed in macrophage-rich tissues, such as spleen, lung, and liver and are abundant in primary macrophages. Immunoblotting and immunoprecipitation analyses identify Naip protein expression in mouse macrophages and in macrophage cell lines RAW 264.7 and J774A. Interestingly, macrophages from permissive A/J mice express significantly less Naip protein than their nonpermissive C57BL/6J counterpart. Naip protein expression is increased after phagocytic events. Naip protein levels during infection with either virulent or avirulent strains of L. pneumophila increase during the first 6 h postinfection and remain elevated during the 48-h observation period. This enhanced expression is also observed in macrophages infected with Salmonella typhimurium. Likewise, an increase in Naip protein levels in macrophages is observed 24 h after phagocytosis of Latex beads. The cosegregation of Lgn1 and Naip together with the detected Naip protein expression in host macrophages as well as its modulation after phagocytic events and during intracellular infection make it an attractive candidate for the Lgn1 locus.

Expression and regulation of neuronal apoptosis inhibitory protein during adipocyte differentiation

We have used the 3T3-L1 and 3T3-F442A preadipocyte cell lines to examine the expression and regulation of neuronal apoptosis inhibitory protein (NAIP) during adipocyte differentiation. When 3T3-L1 preadipocytes differentiated into adipocytes, they developed resistance to apoptosis induced by growth factor deprivation, as assessed by terminal deoxynucleotide transferase (TdT)-mediated dUTP nick end labeling. Protein expression of NAIP was markedly elevated in 3T3-L1 and 3T3-F442A adipocytes compared with that in their fibroblast-like precursors. NAIP was also present in rat white adipocytes. In 3T3-L1 cells, the increase in NAIP occurred by day 4 of the 8-day differentiation protocol, which includes exposure of confluent preadipocytes to insulin, dexamethasone, and isobutylmethylxanthine. Incubation of confluent 3T3-L1 preadipocytes with any of these components alone had no effect on NAIP expression. When 3T3-C2 cells, a control cell line that does not differentiate, were subjected to the differentiation protocol, the low NAIP levels remained unaltered. Addition of rapamycin, a p70 S6 kinase inhibitor that blocks adipocyte differentiation, to the 3T3-L1 differentiation medium prevented the rise in NAIP expression. These data demonstrate for the first time that NAIP is expressed in adipocyte cell lines and primary adipocytes. The differentiation-dependent augmentation of NAIP protein levels in 3T3-L1 adipocytes is closely correlated with the development of resistance to apoptosis induced by growth factor deprivation, suggesting a potential role for NAIP in these cells.

Cloning and characterization of the multiple murine homologues of NAIP (neuronal apoptosis inhibitory protein)

The spinal muscular atrophies (SMAs), characterized by degeneration of spinal cord motor neurons, are among the most common autosomal recessive disorders. We have previously reported the characterization of an SMA-associated gene designated NAIP (neuronal apoptosis inhibitory protein). This gene, which encodes a protein homologous to the baculoviral inhibitor of apoptosis proteins, is deleted in a significant proportion of individuals with type I SMA, is expressed in motor neurons, and inhibits apoptosis both in vitro and in vivo. Here we present the cloning and characterization of multiple copies of the mouse homologue of NAIP, Naip1-Naip6. Our analysis of the genomic organization of Naip indicated the existence of a minimum of six distinct Naip loci in the 129/SvJ mouse strain. However, Southern blot analysis revealed that only three of these loci contained the 5'UTR element essential for translation in the CNS. The coding region of one of these three potentially functional loci (Naip1) demonstrates 77% homology to NAIP at the nucleotide level and 68% identity at the amino acid level.

A recombination event occurring within two complex 5q13.1 microsatellite repeat polymorphisms suggests a telomeric mapping of spinal muscular atrophy

The gene for the childhood spinal muscular atrophies (SMAs) has been mapped to 5q13.1. The interval containing the SMA gene has been defined by linkage analysis as 5qcen-D5S629-SMA-D5S557-5qter. We have identified a recombination event within this interval on a type-I SMA chromosome. The recombination maps to a region of multilocus microsatellite repeat (MSR) markers, and occurs between different subloci of two such markers, CMS-1 and 7613. While the possibility of a novel mutation caused by the recombination cannot be discounted, we believe when viewed in the context of a similar recombination in a Dutch SMA family, a centromeric boundary at the recombination site for the critical SMA interval is likely. This new proximal boundary would reduce the minimal region harboring the SMA locus from approximately 1.1 Mb to approximately 600 kb.

Refined physical map of the spinal muscular atrophy gene (SMA) region at 5q13 based on YAC and cosmid contiguous arrays

The gene for the autosomal recessive neurodegenerative disorder spinal muscular atrophy has been mapped to a region of 5q13 flanked proximally by CMS-1 and distally by D5S557. We present a 2-Mb yeast artificial chromosome (YAC) contig constructed from three libraries encompassing the D5S435/D5S629/CMS-1-SMA-D5S557/D5S112 interval. The D5S629/CMS-1-SMA-D5S557 interval is unusual insofar as chromosome 5-specific repetitive sequences are present and many of the simple tandem repeats (STR) are located at multiple loci that are unstable in our YAC clones. A long-range restriction map that demonstrates the SMA-containing interval to be 550 kb is presented. Moreover, a 210-kb cosmid array from both a YAC-specific and a chromosome 5-specific cosmid library encompassing the multilocus STRs CATT-1, CMS-1, D5F149, D5F150, and D5F153 has been assembled. We have recently reported strong linkage disequilibrium with Type I SMA for two of these STRs, indicating that the gene is located in close proximity to or within our cosmid clone array.

The gene for neuronal apoptosis inhibitory protein is partially deleted in individuals with spinal muscular atrophy

The spinal muscular atrophies (SMAs), characterized by spinal cord motor neuron depletion, are among the most common autosomal recessive disorders. One model of SMA pathogenesis invokes an inappropriate persistence of normally occurring motor neuron apoptosis. Consistent with this hypothesis, the novel gene for neuronal apoptosis inhibitory protein (NAIP) has been mapped to the SMA region of chromosome 5q13.1 and is homologous with baculoviral apoptosis inhibitor proteins. The two first coding exons of this gene are deleted in approximately 67% of type I SMA chromosomes compared with 2% of non-SMA chromosomes. Furthermore, RT-PCR analysis reveals internally deleted and mutated forms of the NAIP transcript in type I SMA individuals and not in unaffected individuals. These findings suggest that mutations in the NAIP locus may lead to a failure of a normally occurring inhibition of motor neuron apoptosis resulting in or contributing to the SMA phenotype.

Nucleotide sequences of the fecBCDE genes and locations of the proteins suggest a periplasmic-binding-protein-dependent transport mechanism for iron(III) dicitrate in Escherichia coli

The fec region of the Escherichia coli chromosome determines a citrate-dependent iron(III) transport system. The nucleotide sequence of fec revealed five genes, fecABCDE, which are transcribed from fecA to fecE. The fecA gene encodes a previously described outer membrane receptor protein. The fecB gene product is formed as a precursor protein with a signal peptide of 21 amino acids; the mature form, with a molecular weight of 30,815, was previously found in the periplasm. The fecB genes of E. coli B and E. coli K-12 differed in 3 nucleotides, of which 2 gave rise to conservative amino acid exchanges. The fecC and fecD genes were found to encode very hydrophobic polypeptides with molecular weights of 35,367 and 34,148, respectively, both of which are localized in the cytoplasmic membrane. The fecE product was a rather hydrophilic but cytoplasmic membrane-bound protein of Mr 28,189 and contained regions of extensive homology to ATP-binding proteins. The number, structural characteristics, and locations of the FecBCDE proteins were typical for a periplasmic-binding-protein-dependent transport system. It is proposed that after FecA- and TonB-dependent transport of iron(III) dicitrate across the outer membrane, uptake through the cytoplasmic membrane follows the binding-protein-dependent transport mechanism. FecC and FecD exhibited homologies to each other, to the N- and C-terminal halves of FhuB of the iron(III) hydroxamate transport system, and to BtuC of the vitamin B12 transport system. FecB showed some homology to FhuD, suggesting that the latter may function in the same manner as a binding protein in iron(III) hydroxamate transport. The close homology between the proteins of the two iron transport systems and of the vitamin B12 transport system indicates a common evolution for all three systems.