Desflurane consumption during automated closed-circuit delivery is higher than when a conventional anesthesia machine is used with a simple vaporizer-O2-N2O fresh gas flow sequence

Background

Current analgesics have drawbacks such as delays in acquisition, lag-times for effect, and side effects. We recently presented a preliminary report of a new analgesic method involving a two-minute sciatic nerve press, which resulted in immediate short-term relief of pain associated with dental and renal diseases. The present study investigated whether this technique was effective for pain associated with other disease types, and whether the relief was effective for up to one hour.

Methods

This randomized, placebo-controlled, parallel-group trial was conducted in four hospitals in Anhui Province, China. Patients with pain were sequentially recruited by participating physicians during clinic visits, and 135 patients aged 15 – 80 years were enrolled. Dental disease patients included those with acute pulpitis and periapical abscesses. Renal disease patients included those with kidney infections and/or stones. Tumor patients included those with nose, breast, stomach and liver cancers, while Emergency Room patients had various pathologies. Patients were randomly assigned to receive a "sciatic nerve press" in which pressure was applied simultaneously to the sciatic nerves at the back of both thighs, or a "placebo press" in which pressure was applied to a parallel region on the front of the thighs. Each fist applied a pressure of 11 – 20 kg for 2 minutes. Patients rated their level of pain before and after the procedure.

Results

The "sciatic nerve press" produced immediate relief of pain in all patient groups. Emergency patients reported a 43.5% reduction in pain (p < 0.001). Significant pain relief for dental, renal and tumor patients lasted for 60 minutes (p < 0.001). The peak pain relief occurred at the 10 – 20^th minutes, and the relief decreased 47% by the 60^th minutes.

Conclusion

Two minutes of pressure on both sciatic nerves produced immediate significant short-term conduction analgesia. This technique is a convenient, safe and powerful method for the short-term treatment of clinical pain associated with a diverse range of pathologies.

Trial registration

Current Controlled Trials ACTRN012606000439549     

Amphibian Melanophore Technology as a Functional Screen for Antagonists of G-Protein Coupled 7-Transmembrane Receptors

Xenopus laevis melanophores stably expressing 7-transmembrane G-protein-coupled receptors were established and evaluated, either as a primary screening utility for antagonists of the human calcium receptor, or as a screen to assign function to binding inhibitors of human cannabinoid receptors. Stably or transiently expressing melanophores responded selectively to respective effectors of the human calcium, cannabinoid, and neurokinin-1 receptors. Several selective cannabinoid receptor-binding inhibitors of known potency were characterized as agonists or antagonists of the human peripheral cannabinoid (CB(2)) receptor. The results were consistent with changes in cAMP content of hCB(2)-transfected human embryonic kidney (HEK) cells challenged with the same CB(2)-binding antagonists. A stable melanophore cell line expressing the human calcium receptor was used to screen a compound collection directly for functional antagonists, several of which were confirmed as antagonists in secondary screens by stimulating parathyroid hormone (PTH) secretion from bovine parathyroid cells. The percentage of hits in this cell-based screen was reasonably low (1.2%), indicating minimal interference due to toxic effects and validating melanophores as a primary screening modality. Also described is the development of a novel procedure for cryopreservation and reconstitution of cells retaining functional human receptors. ()     

Reproducibility of Frankfort Horizontal Plane on 3D Multi-Planar Reconstructed MR Images

Objective

The purpose of this study was to determine the accuracy and reliability of Frankfort horizontal plane identification using displays of multi-planar reconstructed MRI images, and propose it as a sufficiently stable and standardized reference plane for craniofacial structures.

Materials and Methods

MRI images of 43 subjects were obtained from the longitudinal population based cohort study SHIP-2 using a T1-weighted 3D sequence. Five examiners independently identified the three landmarks that form FH plane. Intra-examiner reproducibility and inter-examiner reliability, correlation coefficients (ICC), coefficient of variability and Bland-Altman plots were obtained for all landmarks coordinates to assess reproducibility. Intra-examiner reproducibility and inter-examiner reliability in terms of location and plane angulation were also assessed.

Results

Intra- and inter-examiner reliabilities for X, Y and Z coordinates of all three landmarks were excellent with ICC values ranging from 0.914 to 0.998. Differences among examiners were more in X and Z than in Y dimensions. The Bland–Altman analysis demonstrated excellent intra- as well as inter-examiner agreement between examiners in all coordinates for all landmarks. Intra-examiner reproducibility and inter-examiner reliability of the three landmarks in terms of distance showed mean differences between 1.3 to 2.9 mm, Mean differences in plane angulation were between 1.0° to 1.5° among examiners.

Conclusion

This study revealed excellent intra-examiner reproducibility and inter-examiner reliability of Frankfort Horizontal plane through 3D landmark identification in MRI. Sufficiently stable landmark-based reference plane could be used for different treatments and studies.     

Lack of geographic variation in anonymous nuclear polymorphisms in the American oyster, Crassostrea virginica

Comparing geographic variation of noncoding nuclear DNA polymorphisms, which presumably are neutral to natural selection, with geographic variation of allozymes is potentially a good way to detect the effects of selection on allozyme polymorphisms. A previous study of four anonymous nuclear markers in the American oyster, Crassostrea virginica, found dramatic differences in allele frequency between the Gulf of Mexico and the Atlantic Ocean. In contrast, 14 allozyme polymorphisms were fairly uniform in frequency between the two areas. This led to the conclusion that all of the allozyme polymorphisms were kept uniform in frequency by balancing selection. To test the robustness of this pattern, six additional anonymous nuclear DNA polymorphisms were surveyed in oysters from Panacea, Fla, and Charleston, S.C. on the Gulf and Atlantic coasts, respectively. Unlike the previously studied DNA markers, the six DNA polymorphisms examined here show geographic variation that is not significantly greater than that of allozymes. The reason for the discrepancy between the two sets of DNA polymorphisms is unclear.      

Top-down Proteomics Reveals Concerted Reductions in Myofilament and Z-disc Protein Phosphorylation after Acute Myocardial Infarction

Heart failure (HF) is a leading cause of morbidity and mortality worldwide and is most often precipitated by myocardial infarction. However, the molecular changes driving cardiac dysfunction immediately after myocardial infarction remain poorly understood. Myofilament proteins, responsible for cardiac contraction and relaxation, play critical roles in signal reception and transduction in HF. Post-translational modifications of myofilament proteins afford a mechanism for the beat-to-beat regulation of cardiac function. Thus it is of paramount importance to gain a comprehensive understanding of post-translational modifications of myofilament proteins involved in regulating early molecular events in the post-infarcted myocardium. We have developed a novel liquid chromatography–mass spectrometry-based top-down proteomics strategy to comprehensively assess the modifications of key cardiac proteins in the myofilament subproteome extracted from a minimal amount of myocardial tissue with high reproducibility and throughput. The entire procedure, including tissue homogenization, myofilament extraction, and on-line LC/MS, takes less than three hours. Notably, enabled by this novel top-down proteomics technology, we discovered a concerted significant reduction in the phosphorylation of three crucial cardiac proteins in acutely infarcted swine myocardium: cardiac troponin I and myosin regulatory light chain of the myofilaments and, unexpectedly, enigma homolog isoform 2 (ENH2) of the Z-disc. Furthermore, top-down MS allowed us to comprehensively sequence these proteins and pinpoint their phosphorylation sites. For the first time, we have characterized the sequence of ENH2 and identified it as a phosphoprotein. ENH2 is localized at the Z-disc, which has been increasingly recognized for its role as a nodal point in cardiac signaling. Thus our proteomics discovery opens up new avenues for the investigation of concerted signaling between myofilament and Z-disc in the early molecular events that contribute to cardiac dysfunction and progression to HF.Despite recent advances in the treatment of heart failure (HF),¹ this devastating syndrome remains a leading cause of morbidity and mortality worldwide and imposes a significant economic burden, especially on developed countries (1–3). The most common cause of HF, myocardial infarction (MI), induces left ventricular (LV) remodeling characterized by chamber dilation and hypertrophy of the non-infarcted (remote) myocardium, which is ultimately maladaptive, leading to depressed global contractility and predisposing the heart to failure (4). Current treatments for HF have primarily focused on symptom management after the occurrence of irreversible remodeling and functional impairment, which only delays the syndrome (1). Understanding the molecular mechanisms driving cardiac dysfunction at the early stages could enable the development of therapeutic interventions to prevent the onset of HF. However, the molecular changes that occur immediately after MI but prior to the maladaptive remodeling remain poorly understood (5).Myofilaments are responsible for cardiac contraction and relaxation and play a central role in myocardial pathophysiology (6, 7). Moreover, recent evidence suggests that cardiac myofilaments have a critical role in signal reception and transduction in HF (8, 9). Myofilaments consist of thin filament proteins, which include actin, tropomyosin (Tm), and the troponin (Tn) complex (TnI, TnT, and TnC), and thick filament proteins including myosin (S-1 head domain, S-2 rod domain, essential light chain, and regulatory light chain (MLC2)), as well as a number of accessory proteins such as myosin binding protein C (6, 10–12). In addition to these major myofilament proteins, a significant number of proteins have been identified in the cardiac myofilament subproteome (13). Cardiac contraction requires the integrated activity of highly coordinated protein–protein interactions among myofilament proteins in the sarcomere (6, 8, 9). Post-translational modifications (PTMs) and mutations of myofilament proteins can change these protein–protein interactions, thereby altering cardiac contractility. Thus, it is of paramount importance to gain a comprehensive understanding of the PTM changes of myofilament proteins in the regulation of early molecular events in contractile dysfunction immediately after acute myocardial infarction (AMI).Top-down mass spectrometry (MS) (12, 14–22) has unique advantages for the comprehensive assessment of protein modifications through the detection and quantification of all proteoforms (a unified term used to define all of the different molecular forms arising from PTMs, mutations or polymorphisms, and alternative splicing events (23)). Subsequently, the modification sites can be precisely localized via MS/MS including but not limited to collisionally activated dissociation (CAD) and electron capture dissociation (ECD) (12, 14–22, 24, 25). We have successfully developed a novel liquid chromatography–mass spectrometry (LC/MS)-based top-down quantitative proteomics strategy to assess the concerted changes in myofilaments and their associated proteins in the myofilament subproteome. Specifically, we have rapidly separated and quantified intact proteins extracted from a minimal amount of myocardial tissue (∼500 μg of tissue per experiment) by means of LC/MS with high reproducibility and throughput. Notably, we discovered a concerted significant reduction in the phosphorylation of three crucial cardiac proteins in acutely infarcted myocardium using a clinically relevant swine AMI model (26): a thin filament regulatory protein, cardiac TnI (cTnI); a thick filament regulatory protein, MLC2; and, unexpectedly, a critical Z-disc protein, enigma homolog isoform 2 (ENH2). Subsequently, we unambiguously localized the phosphorylation sites of these three important proteins using ECD. Particularly, for the first time, we comprehensively sequenced swine ENH2 by means of top-down MS and identified it as a phosphoprotein with its phosphorylation site precisely pinpointed. ENH2 belongs to the PDZ-LIM protein family that co-localizes with α-actinin at the Z-disc (27, 28). Although traditionally viewed as a structural component in the sarcomere, the Z-disc is increasingly recognized for its prominent role as a nodal point for cardiac signaling (27, 29, 30). Thus, our proteomic discovery opens up new avenues for investigations of the concerted signaling between myofilament and Z-disc proteins in the early molecular events that may contribute to cardiac dysfunction and subsequent HF.     

Dynamic flexibility of double-stranded RNA activated PKR in solution

PKR, an interferon-induced double-stranded RNA activated serine-threonine kinase, is a component of signal transduction pathways mediating cell growth control and responses to stress and viral infection. Analysis of separate PKR functional domains by NMR and X-ray crystallography has revealed details of PKR RNA binding domains and kinase domain, respectively. Here, we report the structural characteristics, calculated from biochemical and neutron scattering data, of a native PKR fraction with a high level of autophosphorylation and constitutive kinase activity. The experiments reveal association of the protein monomer into dimers and tetramers, in the absence of double-stranded RNA or other activators. Low-resolution structures of the association states were obtained from the large angle neutron scattering data and reveal the relative orientation of all protein domains in the activated kinase dimer. Low-resolution structures were also obtained for a PKR tetramer-monoclonal antibody complex. Taken together, this information leads to a new model for the structure of the functioning unit of the enzyme, highlights the flexibility of PKR and sheds light on the mechanism of PKR activation. The results of this study emphasize the usefulness of low-resolution structural studies in solution on large flexible multiple domain proteins.     

Reduced male fertility is common but highly variable in form and severity in a natural house mouse hybrid zone

Barriers to gene flow between naturally hybridizing taxa reveal the initial stages of speciation. Reduced hybrid fertility is a common feature of reproductive barriers separating recently diverged species. In house mice (Mus musculus), hybrid male sterility has been studied extensively using experimental crosses between subspecies. Here, we present the first detailed picture of hybrid male fertility in the European M. m. domesticus-M. m. musculus hybrid zone. Complete sterility appears rare or absent in natural hybrids but a large proportion of males (~30%) have sperm count or relative testis weight below the range in pure subspecies, and likely suffer reduced fertility. Comparison of a suite of traits related to fertility among subfertile males indicates reduced hybrid fertility in the contact zone is highly variable among individuals and ancestry groups in the type, number, and severity of spermatogenesis defects present. Taken together, these results suggest multiple underlying genetic incompatibilities are segregating in the hybrid zone, which likely contribute to reproductive isolation between subspecies.     

Effect of lactoperoxidase on the antimicrobial effectiveness of the thiocyanate hydrogen peroxide combination in a quantitative suspension test

Background  

The positive antimicrobial effects of increasing concentrations of thiocyanate (SCN-) and H₂O₂ on the human peroxidase defence system are well known. However, little is known about the quantitative efficacy of the human peroxidase thiocyanate H₂O₂ system regarding Streptococcus mutans and sanguinis, as well as Candida albicans. The aim of this study was to evaluate the effect of the enzyme lactoperoxidase on the bactericidal and fungicidal effectiveness of a thiocyanate-H₂O₂ combination above the physiological saliva level. To evaluate the optimal effectiveness curve, the exposure times were restricted to 1, 3, 5, and 15 min.