Systematic review of benefits or harms of routine anaesthetist-inserted throat packs in adults: practice recommendations for inserting and counting throat packs: An evidence-based consensus statement by the Difficult Airway Society (DAS), the British Association of Oral and Maxillofacial Surgery (BAOMS) and the British Association of Otorhinolaryngology, Head and Neck Surgery (ENT-UK).

Throat packs are commonly inserted by anaesthetists after induction of anaesthesia for dental, maxillofacial, nasal or upper airway surgery. However, the evidence supporting this practice as routine is unclear, especially in the light of accidentally retained throat packs which constitute 'Never Events' as defined by NHS England. On behalf of three relevant national organisations, we therefore conducted a systematic review and literature search to assess the evidence base for benefit, and also the extent and severity of complications associated with throat pack use. Other than descriptions of how to insert throat packs in many standard texts, we could find no study that sought to assess the benefit of their insertion by anaesthetists. Instead, there were many reports of minor and major complications (the latter including serious postoperative airway obstruction and at least one death), and many descriptions of how to avoid complications. As a result of these findings, the three national organisations no longer recommend the routine insertion of throat packs by anaesthetists but advise caution and careful consideration. Two protocols for pack insertion are presented, should their use be judged necessary.

Species-specific in vitro pharmacological effects of the cannabinoid receptor 2 (CB2) selective ligand AM1241 and its resolved enantiomers.

BACKGROUND AND PURPOSE: Racemic (R,S) AM1241 is a cannabinoid receptor 2 (CB(2))-selective aminoalkylindole with antinociceptive efficacy in animal pain models. The purpose of our studies was to provide a characterization of R,S-AM1241 and its resolved enantiomers in vitro and in vivo. EXPERIMENTAL APPROACH: Competition binding assays were performed using membranes from cell lines expressing recombinant human, rat, and mouse CB(2) receptors. Inhibition of cAMP was assayed using intact CB(2)-expressing cells. A mouse model of visceral pain (para-phenylquinone, PPQ) and a rat model of acute inflammatory pain (carrageenan) were employed to characterize the compounds in vivo. KEY RESULTS: In cAMP inhibition assays, R,S-AM1241 was found to be an agonist at human CB(2), but an inverse agonist at rat and mouse CB(2) receptors. R-AM1241 bound with more than 40-fold higher affinity than S-AM1241, to all three CB(2) receptors and displayed a functional profile similar to that of the racemate. In contrast, S-AM1241 was an agonist at all three CB(2) receptors. In pain models, S-AM1241 was more efficacious than either R-AM1241 or the racemate. Antagonist blockade demonstrated that the in vivo effects of S-AM1241 were mediated by CB(2) receptors. CONCLUSIONS AND IMPLICATIONS: These findings constitute the first in vitro functional assessment of R,S-AM1241 at rodent CB(2) receptors and the first characterization of the AM1241 enantiomers in recombinant cell systems and in vivo. The greater antinociceptive efficacy of S-AM1241, the functional CB(2) agonist enantiomer of AM1241, is consistent with previous observations that CB(2) agonists are effective in relief of pain.

Both estrogen receptor alpha and estrogen receptor beta agonists enhance cell proliferation in the dentate gyrus of adult female rats.

This study investigated the involvement of estrogen receptors alpha and beta in estradiol-induced enhancement of hippocampal neurogenesis in the adult female rat. Subtype selective estrogen receptor agonists, propyl-pyrazole triol (estrogen receptor alpha agonist) and diarylpropionitrile (estrogen receptor beta agonist) were examined for each receptor's contribution, individual and cooperative, for estradiol-enhanced hippocampal cell proliferation. Estradiol increases hippocampal cell proliferation within 4 h [Ormerod BK, Lee TT, Galea LA (2003) Estradiol initially enhances but subsequently suppresses (via adrenal steroids) granule cell proliferation in the dentate gyrus of adult female rats. J Neurobiol 55:247-260]. Therefore, animals received s.c. injections of estradiol (10 microg), propyl-pyrazole triol and diarylpropionitrile alone (1.25, 2.5, 5.0 mg/0.1 ml dimethylsulfoxide) or in combination (2.5 mg propyl-pyrazole triol+2.5 mg diarylpropionitrile/0.1 ml dimethylsulfoxide) and 4 h later received an i.p. injection of the cell synthesis marker, bromodeoxyuridine (200 mg/kg). Diarylpropionitrile enhanced cell proliferation at all three administered doses (1.25 mg, P<0.008; 2.5 mg, P<0.003; 5 mg, P<0.005), whereas propyl-pyrazole triol significantly increased cell proliferation (P<0.0002) only at the dose of 2.5 mg. Our results demonstrate both estrogen receptor alpha and estrogen receptor beta are individually involved in estradiol-enhanced cell proliferation. Furthermore both estrogen receptor alpha and estrogen receptor beta mRNA was found co-localized with Ki-67 expression in the hippocampus albeit at low levels, indicating a potential direct influence of each receptor subtype on progenitor cells and their progeny. Dual receptor activation resulted in reduced levels of cell proliferation, supporting previous studies suggesting that estrogen receptor alpha and estrogen receptor beta may modulate each other's activity. Our results also suggest that a component of estrogen receptor-regulated cell proliferation may take place through alternative ligand and/or cell-signaling mechanisms.

Modulational instability of spatially broadband nonlinear optical pulses in four-state atomic systems.

The modulational instability of broadband optical pulses in a four-state atomic system is investigated. In particular, starting from a recently derived generalized nonlinear Schrödinger equation, a wave-kinetic equation is derived. A comparison between coherent and random-phase wave states is made. It is found that the spatial spectral broadening can contribute to the nonlinear stability of ultrashort optical pulses. In practical terms, this could be achieved by using random-phase plate techniques.

The organization and expression of the light gene, a heterochromatic gene of Drosophila melanogaster.

The light (lt) gene is located in the centromeric heterochromatin of chromosome 2 of Drosophila melanogaster. This gene is necessary for normal levels of pigmentation in a number of adult and larval tissues and is required for viability. Hybrid dysgenic and X-ray induced mutations have been used to identify the gene and compare its organization to that of euchromatic genes. Molecular mapping of lt mutations and its major transcripts has shown that the lt gene is at least 17 kb. By injecting cosmid clones that include this region into lt mutant embryos, we have defined a 30-kb region that can transiently rescue the pigmentation defect in the Malpighian tubules. The major transcription unit of this gene is comprised of exons that are single copy. It is unusual in its organization in having a heterogeneous array of middle repetitive DNA sequences within its intronic and flanking regions.

Targeted selection experiments and enzyme polymorphism: negative evidence for octanoate selection at the G6PD locus in Drosophila melanogaster.

Published studies have reported significant selection with respect to the G6pd locus for Drosophila melanogaster reared on Na-octanoate food. We have reexamined the selective effects of Na-octanoate on egg to adult viability with respect to the G6pd polymorphism using specially constructed X chromosomes. Four experiments were carried out using different 6Pgd backgrounds in two recombinant sets of chromosomes segregating for the G6pd locus but constructed so as to minimize variation over most of the X chromosome. In addition, two measures of viability were used, and the size of the experiments and their associated degrees of freedom are approximately double those reported in the former studies. Our results find no evidence for differential selection on G6pd genotypes (males and females) by Na-octanoate and, therefore, do not corroborate the positive results of selection reported by other investigators. The reasons for our different results are discussed.

A functional polyadenylation signal is embedded in the coding region of chicken growth hormone receptor RNA.

A study of chicken GH receptor (cGHR) expression has revealed that the two major liver and skeletal muscle transcripts of the cGHR are developmentally expressed. Expression of the larger (4.7 kilobases) transcript increases with age. The smaller transcript (0.7 kilobases) is a truncation product, resulting from alternative usage of a functional polyadenylation [poly(A)] signal embedded in the coding sequence. The extent to which alternative cleavage and polyadenylation occur displays some tissue and sex specificity. Cleavage and polyadenylation occur down-stream of the AATAAA portion of the poly(A) signal (cGHR positions 304-309) and up-stream of a GT-rich sequence. The truncated transcript appears to be translated, based on its association in vivo with polyribosomes, although the physiological role of the putative protein product of this truncated transcript is as yet unknown. Three other avian species (quail, turkey, and duck) also show a polyadenylated truncation of the GHR message due to a poly(A) signal at the same location in the coding sequence. In cell culture expression, mutation of AATAAA to AACAAG prevents production of the truncated transcript. In a chimeric construct, the signal and neighboring sequence from the cGHR are sufficient to confer cleavage and polyadenylation upon the rat GHR, a gene that otherwise lacks the internal poly(A) signal. Alternative polyadenylation within the coding region of a structural gene is discussed as a heretofore unknown means of post-transcriptional regulation of a gene product.

Unfounded worries about cancer in patients attending a routine otolaryngology clinic.

To investigate a suspicion that many ear, nose and throat patients have unfounded concerns about cancer, we questioned 50 patients who had attended a routine clinic after screening-out of those with possibly cancer-related features. None of the 50 proved to have cancer. 15 (30%) had been worried about cancer and 7 of these were still worried despite the consultation. Unwarranted fears about cancer are best dealt with by the referring clinician, especially when the wait for an appointment will be long. Such fears also need to be recognized and addressed by the specialist.

One class of growth hormone (GH) receptor and binding protein messenger ribonucleic acid in rat liver, GHR1, is sexually dimorphic and regulated by GH.

In the rat, alternatively spliced messenger RNA (mRNA) species encode GH receptor (GHR) and GH-binding protein (GHBP). Additionally, these mRNAs are alternatively spliced in the 5'-untranslated region, resulting in at least two classes of GHR and GHBP mRNA with distinct first exons and identical coding regions. These alternative first exons define two unique classes of GHR and GHBP mRNA (called GHR1 and GHR2). The GHR1 class of RNA is expressed only in the liver, is far more abundant in females than males, and is particularly abundant during pregnancy. GHR1 RNA is induced later in development than is GHR2. Additional classes of GHR and GHBP RNA may also exist. The genomic structure of the GHR1 first exon reveals a putative promotor region with no TATA box, CAAT box, or other sequence elements suggesting specific responses. An in vivo approach was used to investigate the regulation of GHR1 expression. In female rats, gonadectomy was found to reduce the percentage of steady state GHR1 RNA levels in the liver, whereas male castration resulted in an induction of GHR1 RNA. However, short-term treatment with estrogen or testosterone had little effect, suggesting that direct regulation of GHR1 expression may occur through effector(s) other than gonadal steroids. Hypophysectomy abolished GHR1 RNA in females. Treatment of hypophysectomized females and castrated males with GH by single injection did not significantly induce GHR1 RNA, but treatment by continuous infusion of GH did. Little change in non-GHR1 RNA levels was observed for each of these treatments. The results suggest that: 1) the sexual dimorphism observed in total GHR and GHBP RNA in rat liver is attributable to the sexually dimorphic expression of the GHR1 class of RNA; 2) the sexually dimorphic pattern of GH release in rats regulates the GHR1 class of RNA; 3) changes in GHR and GHBP expression observed on gonadectomy, hypophysectomy, GH treatment, and pregnancy are best attributed to GHR1 regulation; and 4) since GHR1 is liver specific, the observed increases in serum GHBP concentration in response to sex steroids, GH pattern, and pregnancy are likely to originate from the liver.

A rapid and sensitive binding assay for growth hormone releasing factor.

A binding assay for growth hormone releasing factor (GRF) has been developed using scintillation proximity assay (SPA) technology. Binding conditions were validated by several criteria. Equilibrium binding was attained within three hours at 22 degrees C in crude membrane fractions of HEK293 (293-P2) and GH4C1 (GH4-P1) cells transfected with the porcine GRF receptor. Saturation binding isotherms produced a KD of 296 pM and a Bmax of 4.7 pmols/mg membrane protein in 293-P2 cells. Cells not expressing the GRF receptor displayed no specific binding for the ligand. Competition binding curves produced the following rank order of potency for tested peptides: GRF analogs D-Ala2 = D-Arg2 (IC50 approximately 1 nM) >> PACAP > secretin, VIP (EC50 > 100 nM). Somatostatin (SRIF) binding was also adapted to the SPA format in a GH4C1 cell line transfected with the SRIF receptor subtype 2 (SSTR2) and in HEK293 cells transfected with the SRIF receptor subtype 5 (SSTR5). This assay represents a major improvement for binding measurements of these and potentially many other ligands for G-protein linked receptors, requiring no separation of bound from free hormone, allowing detailed pharmacological evaluations and enabling measurement of equilibrium binding in real time. In the 96-well format, it is suitable for high throughput screening.

Tissue distribution and ontogeny of growth hormone receptor messenger ribonucleic acid and ligand binding to hepatic tissue in the midgestation sheep fetus.

While circulating GH concentrations are high in fetal life, skeletal growth is only slightly reduced by GH deficiency in utero. This has been explained by the relatively low binding of GH to fetal hepatic tissue, suggesting a lack of GH receptors (GHR). The GHR also recognizes ovine placental lactogen (oPL), which may have a specific role either as a fetal growth-promoting hormone or in regulating fetal metabolism. We investigated GHR expression and membrane binding of ovine (o) GH and oPL in various ovine fetal tissues and in maternal liver at different gestational stages. Singleton-bearing ewes at 51, 95, and 120 days gestation were killed. Liver, muscle, kidney, and brain samples were taken from the fetuses as well as placentas and livers from the ewes (n = 3/gestational age). GHR mRNA measured by Northern blot analysis was expressed at high levels in maternal liver at all gestational stages. A major band was observed at 4.4 kilobases (kb), and three minor bands were observed at 2.5, 1.7, and 8.1 kb. In fetal and placental tissue, only the 4.4-kb band was detected. This was present as early as day 51 of gestation in liver, kidney, lung, heart, and placenta and increased slightly with advancing gestation. On day 51, the expression of GHR mRNA in muscle was negligible, but by day 95, muscle expressed higher concentrations than fetal liver. Placental samples showed only a slight signal, with no change over the gestational range studied. In situ hybridization revealed the placental mRNA to be primarily associated with the decidua. Hepatic tissue showed specific binding to [125I]oGH and [125I]oPL from 51 days gestation. [125I]oPL showed a higher [51 days, 17.9 +/- 1.9% (mean +/- SEM); 95 days, 11.5 +/- 1.6%; 120 days, 16.3 +/- 0.9%] specific binding to the liver membranes than [125I]oGH (51 days, 2.1 +/- 0.7%; 95 days, 2.6 +/- 0.3%; 120 days, 3.5 +/- 0.4%). We conclude that oGHR are present as early as day 51 of gestation in various tissues, including liver. The message appears later in skeletal muscle than in liver. As the GH receptor binds oPL with higher potency than oGH, the parallel ontogenic changes in [125]oGH and [125]oPL binding in the liver do not support the presence of a PL receptor under independent developmental regulation.

Selective uptake of estrogenic compounds by Saccharomyces cerevisiae: a mechanism for antiestrogen resistance in yeast expressing the mammalian estrogen receptor.

Estrogen antagonists such as ICI164,384 do not inhibit 17 beta-estradiol (E2)-dependent gene activity in yeast expressing the mammalian estrogen receptor although these compounds bind to receptors isolated from these cells. Various explanations have been offered for antiestrogen resistance in yeast systems including differences in cell-specific components and lack of permeability of the yeast cell wall to these compounds. We have used a strain of Saccharomyces cerevisiae transformed with the human estrogen receptor gene, and two estrogen response elements linked to a lacZ reporter gene to study the pharmacology of estrogen agonists and antagonists. The rank order of potency of estrogen agonists in this strain (CY525) is similar to that in estrogen-dependent mammalian cells: DES > or = E2 > E1 > E3 = zeranol. Competitive binding with 3H-E2 by these compounds in cell-free extracts of CY525 results in a similar order of potency with a reverse order for E1 and E3. The pure estrogen antagonist ICI164,384 also binds to the receptor from cell-free extracts of CY525 with an IC50 of approximately 14nM. As in mammalian cells ICI164,384 does not induce E2-dependent gene activity. However, unlike mammalian cells, E2-induced gene activity in CY525 is not inhibited by ICI164,384. Intact CY525 cells incubated with 3H-17 beta estradiol were found to specifically bind the labeled ligand since excess unlabeled E2 effectively competed for binding. Unlabeled DES and E1 were also found to compete, however, excess unlabeled ICI164,384, E3 and the second generation antagonist ICI182,720 were unable to displace 3H-E2 binding in intact cells. These results indicate that certain compounds enter the intact yeast cell more readily than others and offer an explanation for antagonist resistance in these organisms.

The CD4+ T lymphocyte is a site of steroid resistance in asthma.

Phytohaemagglutinin (PHA)-induced T-cell proliferation is suppressed completely in steroid-sensitive asthma (SSA) by fluticasone propionate (FP). By contrast, in patients with steroid-resistant asthma (SRA), this proliferative response is only partially attenuated by steroids, which suggests that the T lymphocyte may harbour a key molecular defect in these patients. Both CD4+ and CD8+ T cells may be involved in orchestrating the inflammation underlying asthma. We examined whether CD4+ or CD8+ T cells isolated from SRA and SSA patients are equally susceptible to steroid suppression of PHA-induced proliferation. Complete suppression of CD4+ T-lymphocyte proliferation was seen in both SSA and control subjects at concentrations of 10(-9) M FP. In contrast, proliferation of CD4+ T cells from SRA patients was only partially inhibited, even at 10(-6) M FP. CD8+ responses from SRA, SSA and controls were all similar, with only a partial suppression of proliferation at 10(-6) M FP. Differential suppression by FP of CD4+ T cells has thus been demonstrated between SRA and SSA patients.

Endonasal laser dacryocystorhinostomy: its role in anticoagulated patients.

OBJECTIVE: To report the results of endoscopic laser-assisted dacryocystorhinostomy in anticoagulated patients. STUDY DESIGN: A retrospective study of 16 consecutive anticoagulated patients with distal nasolacrimal duct obstruction treated by endoscopic laser-assisted dacryocystorhinostomy. METHODS: A case note review was made of all patients treated with endoscopic laser-assisted dacryocystorhinostomy who were taking coumadin in two centers between 1993 and 2000. The parameters of age, gender, indications for surgery, surgical findings, complications, and outcome were analyzed. The mean follow-up time was 14 months (range, 9-26 mo). RESULTS: Fifteen of the 16 patients who were treated had an eventual successful outcome, but 6 patients required revision surgery. The patient whose symptoms were not improved was shown to have functional epiphora. No patient had a problem with primary or secondary epistaxis, and no patient required admission. A major benefit was the lack of disruption of anticoagulant therapy. CONCLUSIONS: Endoscopic laser-assisted dacryocystorhinostomy is a safe, efficient technique for the relief of distal nasolacrimal duct obstruction in anticoagulated patients. Not only does it avoid any disruption to their anticoagulant therapy, but it also can be performed as an outpatient procedure.

The embryonic development of the lateral nasal wall from 8 to 24 weeks.

This histological study of 20 fetal heads aged between 8 and 24 weeks of gestation demonstrates and describes the embryonic development of the lateral wall of the nose. The three turbinates (inferior, middle, and superior) arise as soft-tissue swellings (preturbinates) by 8 weeks' gestation. A cartilage capsule surrounds the nose at 8 weeks and by 9 weeks, medially directed flanges of cartilage have invaded all three preturbinates. The uncinate process arises from the medial surface of the lateral cartilaginous capsule and is first identifiable by 10 weeks. An "air space" progressively develops from 11 to 12 weeks lateral to the cartilaginous uncinate process and from this space, the embryonic channel to the maxillary sinus develops. The embryonic woven bone of the maxilla can be identified from 9 to 10 weeks and enlarges both absolutely and relatively to the nasal cavity, so that by 13 to 14 weeks, this expanding bone forms the lateral wall of the inferior meatus as the cartilaginous nasal capsule regresses.

Lysine vasopressin undergoes rapid glycation in the presence of reducing sugars.

Lysine vasopressin (LVP) readily reacts with reducing saccharides both in lyophilized preparations and in aqueous solution. Incubation of LVP with, for example, lactose over a pH range of 3.0-8.5 in phosphate buffer or simply in water, gives rise to a number of reaction products, some of which form rapidly (in a matter of hours) even in the frozen state. Reaction mixtures were analysed by reversed-phase HPLC and the structures of the products were deduced from the amino-acid composition of isolated components, by comparison with product profiles obtained with analogues under similar conditions and by FAB mass-spectral analysis of derivatives isolated after reduction with cyanoborohydride. The primary products arise from the formation of Schiff's bases at one or both of the two amino functions. The alpha-amino group of the N-terminal cystine is considerably more reactive than is the epsilon-amino group of lysine and it is the N-terminal adduct which rapidly forms even at -20 degrees C. It is concluded that caution must be shown in using reducing sugars in formulations containing peptides and proteins, particularly the vasopressins and oxytocin.

Iron-binding affinity of bacterial vaccine polysaccharides which contain phosphodiester linkages as part of the polymer chain and of other polyphosphates, including DNA.

The interaction of iron (II) with bacterial polysaccharides, possessing phosphodiester bonds as part of their polymer chain, has been studied by equilibrium binding dialysis using atomic absorption spectrophotometry. Ferrous ions were found to bind with a stoichiometry of one per two phosphates and with a binding constant of about 2.5 x 10(3) M-1. Similar results, but with larger (ca 1 x 10(4) M-1) binding constants were observed with DNA. This interaction helps explain the depolymerization of polyphosphates which has been observed in the presence of iron salts, and highlights the need to avoid iron contamination of vaccines (and other substances) which contain phosphodiester bonds. The interaction may also be a means of iron sequestration in bacteria which possess these cell-surface polyphosphates.

Ultraviolet Radiation and Distribution of the Solitary Ascidian Corella inflata (Huntsman).

The solitary ascidian Corella inflata is a common fouling organism in many areas of Puget Sound and the San Juan Archipelago, Washington, USA. Despite its abundance, it is conspicuously absent from areas that receive direct sunlight. Previous work suggests that ascidians in unshaded habitats can be overgrown and killed by algal overgrowth. In this study, we tested the hypothesis that UV irradiation contributes to C. inflata distribution by killing individuals exposed to direct sunlight. To test this, we exposed C. inflata embryos, larvae, juveniles, and adults to UV irradiation and measured the responses. We also tested for UV-absorbing compounds in larvae, juveniles, and adults. In the laboratory, UV significantly damaged all life stages; the earliest stages were most vulnerable. A 3-week UV exposure significantly shortened adult life span. Juveniles suffered 100% mortality after only 3 days. Tadpole larvae decreased settlement and metamorphosis after 1 day of UV exposure, and embryos exhibited developmental abnormalities after only 30 minutes of exposure. None of the life-history stages had apparent UV-absorbing compounds. Given the vulnerability of this species to UV, we suggest that its unique life-history traits (i.e., time of spawning, brooding behavior, length of larval life) help it persist in its preferred habitat and avoid dispersal into inappropriate, UV-exposed areas.

Can nasal endoscopy be used to predict residual symptoms after adenoidectomy for nasal obstruction?

BACKGROUND: the efficacy of adenoidectomy in relieving nasal symptoms has been questioned. Although enlarged adenoids are often blamed for nasal obstruction, other causes can be missed if examination is not thorough. We suggest that endoscopy at the time of adenoidectomy may be useful to confirm large adenoids and exclude other causes, and the findings may help predict residual symptoms 2 years after adenoidectomy. METHOD: a prospective study of a consecutive series of children undergoing adenoidectomy for nasal obstruction was performed. All underwent endoscopy with a 4-mm rigid endoscope without decongestants under GA immediately prior to adenoidectomy. Two years later a postal symptom questionnaire was sent, with telephone follow up for non-responders. The findings on endoscopy were compared with residual symptoms at 2 years. RESULTS: Forty-eight children aged 2-9 (mean 4) years were enrolled, 26 of them female. At 2 years follow up, data were available for 34 children (71%). Complete obstruction of the posterior choanae of the nose by adenoids was seen in 21 (62%). Additional findings (e.g. septal deviation, hypertrophic mucosa on the turbinates) were present in 22 (65%). Of them 9 (26%) had residual nasal symptoms. Of the children with less than occlusive adenoids, six (50%) out of 12 had residual symptoms, compared with three (14%) out of 21 with occlusive adenoids (chi(2)=4.91, P<0.05). Although residual symptoms were more common in those with additional findings on the original endoscopy (32 vs. 17%), this did not reach statistical significance. CONCLUSIONS: residual nasal symptoms are common when children are followed up in the medium term. The findings on endoscopy may predict the success of adenoidectomy in relieving the symptoms, and may help to guide further treatment.