Effects of different stocking densities on the development of reproductive and immune functions in young breeder pigeons during the rearing period

1. Stocking density (SD) is closely related to animal performance. This experiment was designed to evaluate the development of reproductive and immune functions of young pigeons under different SDs.2. A total of 288 (half male and half female) 40-day-old pigeons (body weight 400 ± 15 g) were allocated into four groups: High stocking density (HSD; 0.308 m3/bird), standard stocking density (SD; 0.616 m3/bird), and low stocking density (LSD; 1.232 m3/bird) and a caged (control; 0.04125 m3/bird). Every group had six replicates of the same sex.3. The results showed that caged male pigeons had the highest testis index, testosterone content, and gene expression of the androgen receptor gene. LSD treatment induced the highest concentrations of oestradiol, progesterone and mRNA levels of reproductive hormone receptor genes in female pigeons. In male pigeons, the spleen index (organ weight calculated as a percentage of total body weight) showed a peak level (0.09 ± 0.020) in the LSD group, and the thymus index peaked (0.23 ± 0.039) in SD group. However, the index for ovary, spleen, thymus and bursa of Fabricius in female pigeons showed no significant changes among different groups.4. The IL-1β, IL-8, IFN-γ, TGF-β and toll-like receptor 2 (TLR-2) mRNA levels reached their maximum values in both male and female pigeon spleens in the LSD group.5. Young male pigeons housed in cages showed increased testicular development while low stocking density increased the development of reproductive function in young female pigeons. A larger activity space could help enhance the immune function of both male and female pigeons.

Thyroid hormone-responsive protein mediates the response of chicken liver to fasting mainly through the cytokine-cytokine receptor interaction pathway

1. The objective of this study was to explore the mediating role of thyroid hormone-responsive protein (THRSP) in the response of chicken liver to fasting.2. A batch of 7-d-old chicks with similar body weights were randomly divided into the control group and the fasting group (n = 10). The control group was fed ad libitum, while the test group fasted for 24 h. The liver and pectoral muscle tissues were collected. Chicken primary hepatocytes or myocytes were treated with different concentrations of thyroxine, glucose, insulin, oleic acid and palmitic acid, separately. Chicken primary hepatocytes were transfected with THRSP overexpression vector vs. empty vector, and the cells were used for transcriptome analysis. The mRNA expression of THRSP and other genes was determined by quantitative PCR.3. The expression of THRSP in chicken liver and pectoral muscle tissues was significantly inhibited by fasting (P < 0.05). In chicken primary hepatocytes, the expression of THRSP was significantly induced by thyroxine (0.25, 0.5, 1 mmol/l), glucose (50, 100 mmol/l), and insulin (20 nmol/l), and was significantly inhibited by palmitic acid (0.125, 0.25 mmol/l). In the myocytes, expression of THRSP was significantly induced by thyroxine (0.25, 0.5, 1 mmol/l), glucose (50 mmol/l) and oleic acid (0.125, 0.25 mmol/l), was significantly inhibited by insulin (5 nmol/l) and was not significantly affected by palmitic acid.4. Transcriptome analysis showed that overexpression of THRSP significantly affected the expression of 1411 DEGs, of which 1007 were up-regulated and 404 were down-regulated. The GO term and KEGG pathway enrichment analyses showed that these DEGs were mainly enriched in the interaction between cytokine and cytokine receptor and its regulation and signal transduction, cell growth and apoptosis and its regulation, immune response and retinol metabolism.5. In conclusion, the THRSP gene mediates biological effects of fasting by influencing the expressional regulation of the genes related to biological processes such as cytokine-cytokine receptor interaction, cell growth and apoptosis, immune response, retinol metabolism, including TGM2, HSD17B2, RUNX3, IRF1, ANKRD6, UPP2, IKBKE, and PYCR1 genes, in chicken liver.

Therapy-associated remodeling of pancreatic cancer revealed by single-cell spatial transcriptomics and optimal transport analysis

In combination with cell intrinsic properties, interactions in the tumor microenvironment modulate therapeutic response. We leveraged high-plex single-cell spatial transcriptomics to dissect the remodeling of multicellular neighborhoods and cell-cell interactions in human pancreatic cancer associated with specific malignant subtypes and neoadjuvant chemotherapy/radiotherapy. We developed Spatially Constrained Optimal Transport Interaction Analysis (SCOTIA), an optimal transport model with a cost function that includes both spatial distance and ligand-receptor gene expression. Our results uncovered a marked change in ligand-receptor interactions between cancer-associated fibroblasts and malignant cells in response to treatment, which was supported by orthogonal datasets, including an ex vivo tumoroid co-culture system. Overall, this study demonstrates that characterization of the tumor microenvironment using high-plex single-cell spatial transcriptomics allows for identification of molecular interactions that may play a role in the emergence of chemoresistance and establishes a translational spatial biology paradigm that can be broadly applied to other malignancies, diseases, and treatments.

Machine learning guided structure function predictions enable in silico nanoparticle screening for polymeric gene delivery

Developing highly efficient non-viral gene delivery reagents is still difficult for many hard-to-transfect cell types and, to date, has mostly been conducted via brute force screening routines. High throughput in silico methods of evaluating biomaterials can enable accelerated optimization and development of devices or therapeutics by exploring large chemical design spaces quickly and at low cost. This work reports application of state-of-the-art machine learning algorithms to a dataset of synthetic biodegradable polymers, poly(beta-amino ester)s (PBAEs), which have shown exciting promise for therapeutic gene delivery in vitro and in vivo. The data set includes polymer properties as inputs as well as polymeric nanoparticle transfection performance and nanoparticle toxicity in a range of cells as outputs. This data was used to train and evaluate several state-of-the-art machine learning algorithms for their ability to predict transfection and understand structure-function relationships. By developing an encoding scheme for vectorizing the structure of a PBAE polymer in a machine-readable format, we demonstrate that a random forest model can satisfactorily predict DNA transfection in vitro based on the chemical structure of the constituent PBAE polymer in a cell line dependent manner. Based on the model, we synthesized PBAE polymers and used them to form polymeric gene delivery nanoparticles that were predicted in silico to be successful. We validated the computational predictions in two cell lines in vitro, RAW 264.7 macrophages and Hep3B liver cancer cells, and found that the Spearman's R correlation between predicted and experimental transfection was 0.57 and 0.66 respectively. Thus, a computational approach that encoded chemical descriptors of polymers was able to demonstrate that in silico computational screening of polymeric nanomedicine compositions had utility in predicting de novo biological experiments. STATEMENT OF SIGNIFICANCE: Developing highly efficient non-viral gene delivery reagents is difficult for many hard-to-transfect cell types and, to date, has mostly been explored via brute force screening routines. High throughput in silico methods of evaluating biomaterials can enable accelerated optimization and development for therapeutic or biomanufacturing purposes by exploring large chemical design spaces quickly and at low cost. This work reports application of state-of-the-art machine learning algorithms to a large compiled PBAE DNA gene delivery nanoparticle dataset across many cell types to develop predictive models for transfection and nanoparticle cytotoxicity. We develop a novel computational pipeline to encode PBAE nanoparticles with chemical descriptors and demonstrate utility in a de novo experimental context.

The utility of a genetic progression risk test for Barrett esophagus

This study sought to characterize the utility of a gene methylation-based biomarker test that has been validated to predict progression towards esophageal adenocarcinoma. Barrett esophagus (BE) is a precursor condition for esophageal adenocarcinoma (EAC) with somewhat variable approaches among gastroenterologists toward managing neoplastic progression risk. Capsulomics has developed a validated multigene DNA methylation-based biomarker assay performed on BE biopsies designed to address this variability by classifying BE patients into progression risk groups. In the current study, a survey was administered to practicing gastroenterologists in order to assess the potential impact of this assay on clinical practice. In this context, 89% (95% Cl: 85.4-92.6%) of surveyed physicians felt strongly that the multigene Barrett Esophagus test helped resolve uncertainties and optimize care of patients with BE by impacting their decisions on surveillance intervals and use of active treatments, such as ablation. The assay significantly impacted surveillance intervals for both high-risk (22.0 no assay vs 12.3 months with assay; P = 1.7E-8) and low-risk (7.9 no assay vs 11.4 months with assay, P = 8.8E-4) stratified case results. Finally, the assay also significantly impacted decisions to pursue active ablation treatments in both high-risk (5% recommending ablation without assay vs 42% with assay; P = 3.7E-11) and low-risk (42% recommending ablation without assay vs 29% with assay; P = .049) stratified case results. Results demonstrated a strong effect of the assay on clinical decision making, even in conjunction with established clinical guidelines.

Thrombin and factor Xa promote premature senescence and remodeling in areas at risk of the left appendage and in atrial endothelial cells: potential modulation by SGLT1 and/or SGLT2 inhibition

Introduction

Atrial fibrillation (AF), the most common cardiac arrhythmia, promotes prothrombotic responses particularly in the distal part of the left atrial appendage (LAA) characterized by reduced flow and low shear stress. AF occurrence and duration are closely associated with endothelial dysfunction and left atrium remodeling.

The contribution of coagulation factors thrombin and factor Xa (FXa) to LA remodeling remains poorly studied. This study investigated whether thrombin and FXa promote endothelial dysfunction and profibrotic and prothrombotic responses in the distal and proximal parts of the LAA. Since SGLT2 inhibitors have shown pronounced cardiac protection, the contribution of SGLT2 was examined.

Methods

LAAs were harvested from porcine hearts. Proximal (low stasis, high shear) and distal (high stasis, low shear) parts were cut and incubated with a coagulation factor (thrombin or FXa). Left atrial endothelial cells (AECs) were collected enzymatically, cultured and used at passage 1. The level of oxidative stress was assessed using the redox-sensitive probe dihydroethidium (DHE), fibrosis by Sirius red histological staining, senescence-associated β-galactosidase (SA-β-gal) activity using X-gal staining in tissues and the fluorogenic substrate C12FDG and flow cytometry in cells. The expression of target proteins was detected by immunofluorescence staining and Western blot analysis.

Results

The distal part of LAA displayed higher levels of oxidative stress in the endothelium and the atrial wall than the proximal part. SA-β-gal activity, ICAM-1, VCAM-1, and MMP-9 staining was more pronounced in the endothelium of the distal part compared to the proximal part whereas eNOS staining was decreased. The distal LAA wall showed higher levels of fibrosis. Western blot analysis showed higher expression levels of tissue factor (TF), VCAM-1, MCP-1, MMP-9, TGF-β and SGLT-2 in the distal part compared to the proximal one. Both thrombin and FXa increased these signals to a greater extent in the distal part of the LAA whereas the eNOS expression level was decreased. Exposure of AECs to either thrombin or FXa induced a pro-oxidant response and increased the expression level of ICAM-1, TGF-β, MMP-2, MMP-9, SGLT1 and SGLT-2. Thrombin promoted SA-β-gal activity in AECs. The selective SGLT-2 inhibitor empagliflozin and the dual SGLT1/2 inhibitor sotagliflozin prevented the pro-oxidant response and SA-β-gal activity in response to thrombin.

Conclusion

Thus, the distal part of the LAA is prematurely affected by endothelial dysfunction and senescence associated with a pro-oxidant, pro-remodeling and pro-inflammatory response that is further increased by thrombin and FXa. Hence, the coagulation cascade appears to prematurely promote atrial endothelium and wall dysfunction predominantly in areas at risk that may pave the way to thrombus formation. The findings also suggest a potential protective effect of SGLT1 and/or SGLT2 inhibition on atrial dysfunction.

Funding Acknowledgement

Type of funding sources: Private company. Main funding source(s): Unrestricted research grant from Boehringer Ingelheim Pharma GmbH & Co. KG, Biberach, Germany

Protective effects of dapagliflozin on vascular remodeling in the carotid artery following balloon injury – potential role of angiotensin and purinergic signaling

Introduction

Sodium-glucose co-transporter 2 (SGLT2) inhibitors have been shown to reduce the risk of cardiovascular events independently of glycemic control. The possibility that SGLT2 inhibitors improve endothelial regeneration and vascular restenosis is unknown.

Purpose

To examine whether dapagliflozin, a selective SGLT2 inhibitor, could prevent neointima thickening induced by balloon injury and, if so, to determine the underlying mechanisms. The effect of dapagliflozin was compared to that of losartan, an angiotensin type 1 receptor (AT1R) antagonist.

Methods

Saline, dapagliflozin (1.5 mg/kg/day), or losartan (30 mg/kg/day) were administered orally for 5 weeks to male Wistar rats. Balloon injury of the left carotid artery was performed 1 week after starting the treatment and sacrificed 4 weeks later. Vascular reactivity was assessed on left (injured) and right (healthy) carotid artery rings. The extent of neointima was assessed by histomorphometric analysis, changes of target factors by immunofluorescence, RT-qPCR and histochemistry.

Results

Dapagliflozin and losartan treatments reduced neointima thickening by 32% and 27%, respectively. Blunted contractile responses to phenylephrine and relaxations to acetylcholine and down-regulation of eNOS were observed in the injured artery. These effects were not modified by the dapagliflozin or the losartan treatments. RT-qPCR investigations indicated an increased in gene expression of inflammatory (IL-1beta, ITGAM, VCAM-1), oxidative (p47phox, p22phox) and fibrotic (TGF-beta1) markers and a decreased of eNOS in the injured carotid. However, these changes were not affected by the pharmacological treatments. By contrast, significant increased levels of AT1R angiotensin receptor and NTPDase1 (CD39) ectonucleotidase were observed in the restenotic carotid artery of the dapagliflozin group. Histochemical analysis evidenced important NTPDase1 activity in the neointima.

Conclusions

Dapagliflozin effectively reduced neointimal thickening. As the contribution of AT1R and P2Y2 ATP receptor in smooth muscle cell proliferation and neointima formation has been reported in the literature, the present data suggest that dapagliflozin prevents restenosis through interfering with angiotensin and/or extracellular nucleotides signaling. SGLT2 transporter represent potential new target for limiting vascular restenosis.

Funding Acknowledgement

Type of funding sources: Private company. Main funding source(s): This work was supported by AstraZeneca

Totally endoscopic sublay (TES) repair for lateral abdominal wall hernias: technique and first results

BACKGROUND

The optimal surgical treatment for lateral hernias of the abdominal wall remains unclear. The presented prospective study assesses for the first time in detail the clinical value of a totally endoscopic sublay (TES) technique for the repair of these hernias.

METHODS

Twenty-four consecutive patients with a lateral abdominal wall hernia underwent TES repair. This technique is naturally combined with a transversus abdominis release maneuver to create a sufficient retromuscular/preperitoneal space that can accommodate, if necessary, a giant prosthetic mesh.

RESULTS

The operations were successful in all but one patient who required open conversion because of dense intestinal adhesion. The mean defect width was 6.7 ± 3.9 cm. The mean defect area was 78.0 ± 102.4 cm² (range 4-500 cm²). The mean mesh size used was 330.2 ± 165.4 cm² (range 108-900 cm²). The mean operative time was 170.2 ± 73.8 min (range, 60-360 min). The mean visual analog scale score for pain at rest on the first day was 2.5 (range 1-4). The average postoperative stay was 3.4 days (range 2-7 days). No serious complications (Dindo-Clavien Grade 2-4) were seen within a mean follow-up period of 13.3 months.

CONCLUSIONS

A totally endoscopic technique (TES) for the treatment of lateral hernias is described. The technique revealed to be reliable, safe and cost-effective. The first results are promising, but larger studies with longer follow-up periods are recommended to determine the real clinical value.

Retroperitoneal totally endoscopic prosthetic repair of primary lumbar hernia

PURPOSE

A primary lumbar hernia is a rare entity that requires surgical management, but the preferred technique has not been established. We herein describe a standardized and reproducible retroperitoneal totally endoscopic prosthetic (TEP) repair technique for primary lumbar hernias.

METHODS

Ten adult patients with primary lumbar hernias underwent retroperitoneal TEP repair from February 2019 to July 2020. A sufficient retroperitoneal space was established to accommodate a non-coated polypropylene mesh to reinforce the weakened flank area, and hernia content reduction and defect closure were then performed. The patients' clinical data were prospectively collected and analyzed.

RESULTS

Nine patients had a primary superior lumbar hernia and one patient had a primary diffuse lumbar hernia. All operations were successfully performed without serious intraoperative complications. The mean defect area was 6.4 ± 2.8 cm² (range 4-12 cm²), and the mean mesh area was 144.6 cm² (range 130-180 cm²). The average operative time (skin to skin) was 49.0 ± 5.7 min (range 40-60 min), and intraoperative bleeding was minimal. The mean visual analog pain scale score at rest on the first postoperative day was 2.2 (range 2-3). The average length of postoperative stay was 1.5 days (range 1-2 days). No serious postoperative complications occurred. No recurrence, chronic pain, or mesh infection occurred during a mean follow-up period of 7.5 months.

CONCLUSIONS

The retroperitoneal TEP repair for primary lumbar hernias is safe, efficient, and reproducible. Anti-adhesive coated meshes and fixation tackers are not required, making this a cost-effective procedure that is worthy of recommendation.

Single-site laparoscopic percutaneous extraperitoneal closure (SLPEC) of hernia sac high ligation using an ordinary taper needle: a novel technique for pediatric inguinal hernia

PURPOSE

Laparoscopic high ligation of the internal inguinal ring is an alternative procedure for treatment of pediatric inguinal hernia (PIH), with a major trend toward increasing use of extracorporeal knotting and decreasing use of working ports. We have utilized this laparoscopic technique to treat the entire spectrum of PIH (including incarcerated cases) for more than 17 years, and the technique continues to evolve and improve. We herein report our latest modification of this minimally invasive technique, namely single-site laparoscopic percutaneous extraperitoneal closure (SLPEC) of hernia sac high ligation using an ordinary taper needle, and evaluate its safety and efficacy.

METHODS

From July 2016 to July 2019, 790 children with indirect PIH were treated by laparoscopic surgery. All patients underwent high ligation surgery with a modified single-site laparoscopic technique mainly performed by extracorporeal suturing with an ordinary closed-eye taper needle (1/2 arc 11 × 34). The clinical data were retrospectively analyzed.

RESULTS

All surgeries were successful without serious complications. A contralateral patent processus vaginalis (CPPV) was found intraoperatively and subsequently repaired in 190 patients (25.4%). The mean operative time was 15 min (8-25 min) for 557 unilateral hernias and 21 min (14-36 min) for 233 bilateral hernias. The mean postoperative stay was 20 h. Minor complications occurred in five patients (0.63%) and were managed properly, with no major impact on the final outcomes. No recurrence was noted in the patients who were followed up for 6-42 months. No obvious scar was present postoperatively.

CONCLUSION

Modified SLPEC of hernia sac high ligation using an ordinary taper needle for repair of indirect PIH is a safe, reliable, and minimally invasive procedure with satisfactory outcome, with no special device being needed. It is easy to learn and perform and is worthy of popularization in the clinical setting.

[Optical coherence tomography angiography of acute Vogt-Koyanagi-Harada disease]

Objective: To measure vascular density in retinal and choroidal capillary layers by optical coherence tomography angiography (OCTA) and to explore their potential clinical values in Vogt-Koyanagi-Harada disease (VKH). Methods: This is a cross-sectional case-control study. Twenty-one acute VKH cases presented to Peking Union Medical College Hospital between April 2015 and July 2015 and 49 healthy controls were enrolled in this study. OCTA was performed with a split-spectrum amplitude-decorrelation angiography-optical coherence tomography (SSADA-OCT) system borrowed from Optovue Inc. Vascular densities of the capillary layers were analyzed by the built-in software. Bilateral independent sample t-test was used to compare retinal and choroidal vascular density of eyes in acute phase VKH with healthy controls. Spearman correlation test was used to analyze the correlation between the vascular density of retina and choroid in acute phase VKH and LogMAR best corrected visual acuity (BCVA). Results: Mean vascular density of superficial capillary plexus (SCP), deep capillary plexus (DCP) and choriocapillaris (CC) in eyes of the acute VKH group were statistically lower than those of healthy control group (51.56%±2.88%, 56.51%±2.31%, 58.14%±2.10% vs. 53.55%±2.51%, 58.14%±2.10%, 58.14%±2.10%, t=-3.890, 3.910,-6.554, all 3 P values were<0.01). In VKH patients, eyes with retinal detachment (RD) had statistically lower mean vascular density in the CC layer than those without (NRD) (63.46%±2.19% vs. 65.85%±1.79%, t=3.890, P<0.01), while no statistically significant differences were found in vascular densities of SCP and DCP layers between RD and NRD eyes. Spearman's correlation test revealed a negative correlation between vascular density of the CC layer and logMAR BCVA(r=-0.437, P<0.01), while no statistically significant associations were found between logMAR BCVA and vascular densities of SCP and DCP. Conclusions: OCTA can be used for quantitative detection of vascular density of retina and choroidal capillary in acute VKH. There is circulatory disturbance in SCP, DCP and CC of acute VKH. Vascular density of CC is associated with visual acuity and retinal detachment. (Chin J Ophthalmol, 2017, 53: 735-739).

[Progress on Determination and Analysis of Zopiclone in Biological Samples]

As a new hypnotic, zopiclone is widely used in clinical treatment. There are many methods for determination of zopiclone, including spectrophotometry, chromatography and chromatography mass spectrum, etc. Present paper reviews different kinds of biological samples associated with zopiclone, extraction and purification methods, and determination and analysis methods, which aims to provide references for the relevant research and practice.

Depurative capacity of molecular adsorbent recycling system (MARS): A focus on bilirubin removal

The molecular adsorbent recycling system (MARS) is now widely used in the treatment of patients with hepatic failure (HF). A great deal of interest has been directed toward its effect on clinical outcome, whereas its depurative capacity also needs attention. Bilirubin, a tightly albumin-bound toxin accumulating in patients with HF, is regarded as a surrogate to evaluate the depurative capacity of albumin-bound toxins by blood purification modalities. The removal of bilirubin by MARS is difficult to predict, because both the clearance of bilirubin and the reduction ratio of bilirubin after a single session differ between patients and sessions. A reduction of depurative capacity over the course of a treatment is observed. Furthermore, the later sessions are likely less efficient than previous ones. It cannot be taken for granted that the reduction of depurative capacity is due to the saturation and reduced efficiency of the adsorbent columns used in MARS. The answer lies in the property of bilirubin/albumin binding. The removal of bilirubin by MARS is a diffusion process, dependent on the free bilirubin concentration. Bilirubin binds to albumin in 3 ways with different affinity. High-affinity binding bilirubin is difficult to dissociate from albumin and is accompanied by a smaller free fraction, which means it is also difficult for MARS to remove. The factors affecting the free fraction of bilirubin will impact on bilirubin removal by MARS. Among them, the molar ratio of bilirubin to albumin is the most important one. Other factors include the interaction of other agents with bilirubin/albumin binding, the albumin concentration, plasma ion strength, and pH.

Significant Decrease in Dialysate Albumin Concentration during Molecular Adsorbent Recirculating System (M.A.R.S.) Therapy

Aim

The molecular adsorbent recirculating system (M.A.R.S.) is widely used as liver support therapy in patients with hepatic dysfunction. The goal of this study was to measure changes in dialysate albumin and bilirubin concentrations during clinical MARS treatments.

Methods

Eight patients with acute liver dysfunction and hyperbilirubinemia were enrolled in this study. Five of them received a total of 10 treatments with MARS, in which 600 mL of 20% human albumin was used as dialysate, continuously regenerated by two adsorbent columns in the circuit. Three patients received 4 treatments of a modified MARS, in which the two adsorbent columns were bypassed in the first course for 4 h, and then connected to the circuit in the second course for another 4 h. The total, conjugated and unconjugated bilirubin (TB, CB, UCB) and albumin concentrations in serum and albumin dialysate were dynamically measured, and the adsorbent column inlet pressures were recorded during each session. In one session, dialysate albumin levels were measured during the priming process, at the time points prior to the priming process, immediately after priming, and at the end of the treatment.

Results

During MARS therapies, the reduction ratio of serum TB, CB and UCB was 26.6±9.0%, 29.5±9.6% and 14.8±12.3%, respectively. The molar ratio of TB/albumin in serum was approximately 20-fold higher than dialysate at all time points. A significant albumin concentration decrease from baseline in the dialysate was found (mean±SD, 34.6±16.6%). For the first four hours of modified treatments, in which only albumin dialysis without albumin regeneration by adsorbent columns was performed, the dialysate albumin decrease was substantially smaller (mean, 8.3±1.5%). After switching to standard MARS, there was a further decrease in the dialysate albumin concentration of 35.1±14.5%. In one session, dialysate albumin concentrations were measured during the priming process, and levels decreased from 196.9 g/L to 144.4 g/L. Adsorber inlet pressure increased from 40±10mmHg at the start of priming to 150±50mmHg at the end of priming, and further increased to 340±100mmHg at the end of treatment.

Conclusion

There is a significant reduction in dialysate albumin concentration during MARS therapy. Binding of albumin to the adsorbent columns used for albumin regeneration is largely responsible for this decrease.

Improvement of Monocyte Secretion Function in a Porcine Pancreatitis Model by Continuous Dose-Dependent Veno-Venous Hemofiltration

Objective

Monocyte and its secreted cytokines play a crucial role in the process of severe acute pancreatitis (SAP). It has been known that continuous veno-venous hemofiltration (CVVH) can partially attenuate the inflammatory process by removal of cytokines, but the effect of CVVH on monocyte secretion function remains unknown. This study investigated the effect of different doses of CVVH on monocyte secretion function as well as the plasma cytokine profile in a SAP porcine model.

Methods

After successful induction of SAP by pressure-controlled (100 mmHg), intraductal injection of sodium taurocholate (4%, 1 ml/kg) and trypsin (2 U/kg), 24 swine were randomly assigned to 3 groups. Swine in group I (n=8) serving as SAP controls received only standard medical therapy (SMT). Besides SMT, swine in two other groups received zero-balanced CVVH, one hour after the induction of SAP, with low volume fluid exchange (group II, n=8, ultrafiltration rate (UFR) 20 ml/kg/h, LV-CVVH) or high volume (group III, n=8, UFR 100 ml/kg/h, HV-CVVH). Using heparin as anticoagulant, the filter (AN69, Hospal, Lyon, France) was changed every 24 hours. Monocytes were isolated from porcine blood at various timepoints for detection of cytokine secretion (interleukin-6, IL-6; interleukin-10, IL-10; tumor necrosis-α, TNF-α) after LPS stimulus; plasma cytokines were measured simultaneously.

Results

CVVH showed a dose-dependent beneficial effect on the animals’ survival time. In control animals, plasma pro-inflammatory cytokine levels exhibited a double-phase fluctuation after SAP induction: IL-6 and TNF-α rapidly increased to a peak level within 6–12 hours, then dropped to very low level in the late stage. Unlike pro-inflammatory cytokines, the plasma level of anti-inflammatory cytokine IL-10 reached a plateau within 6–12 hours but dropped little. In CVVH-treated animals, the peak-nadir patterns of 3 cytokines were all flattened, most prominently in the HV-CVVH group. Similarly to plasma cytokine patterns, the monocyte ex vivo response to LPS stimulus showed an over-production of cytokines within 6–12 hours, but low production in the late stage. Although unable to totally prevent the abnormality of the monocyte secretion function, CVVH showed a dose-dependent ameliorative effect on it.

Conclusions

Monocytes are over-reactive to stimulus in the early stage of SAP, accompanied by a high level of plasma cytokines, and hypo-reactive to stimulus in the late stage of SAP, accompanied with a low level of plasma cytokines. CVVH treatment has a dose-dependent improvement effect on monocyte responsiveness.

Clustering of Cancer Cell Lines Using A Promoter-Targeted Liquid Hybridization Capture-Based Bisulfite Sequencing Approach

DNA methylation plays a significant role in assuring cell identity, thus potentiating its application in molecular classification of cancers in respect to tissue-origins or clinically and etiologically distinct subtypes. In this study, we optimized our liquid hybridization capture-based bisulfite sequencing (LHC-BS) approach on the gene promoter regions of 11 cell lines. Our results indicated that promoter methylomes could not only cluster cancer cell lines with respect to tissue origins but also differentiate cancer subtypes based on CpG island methylator phenotype (CIMP). Promoter-targeted LHC-BS as means for comprehensive screening and classifying cancer cells with promoter methylomes provided a powerful strategy for further complex clinical studies.

First Report of Chilli ringspot virus on Chili Pepper in China

Viral diseases have been a major limiting factor in the production of chili pepper (Capsicum chinense Jacp. cv. Yellow Lantern) in Hainan Province, China. In a 2009 disease survey, we found heavily infected fields of chili pepper exhibiting typical viral disease symptoms in three counties in Hainan. Total RNA was extracted from leaves of 14 randomly sampled plants and used as templates for reverse transcription (RT)-PCR using a pair of primers (forward 5' CGTAGACAACACACTCATGGT 3', reverse 5' GTTTTCCCAGTCACGAC(T)₁₆ 3') that were originally designed to detect Chilli veinal mottle virus (ChiVMV) (2). PCR fragments of 1.6 kb were amplified from the diseased but not the symptom-free samples and were subsequently sequenced. While most samples were found to be infected with ChiVMV, sequences of PCR fragments from three samples showed identities greater than 90% to two sequences of Chilli ringspot virus (ChiRSV), a member of Potyviridae, available in GenBank (Accession Nos. DQ925439 and DQ925438) (1), but less than 60% to that of the Hainan isolate of ChiVMV (Accession No. GQ981316), a distinct potyvirus (2). Furthermore, two of the samples contained one ChiRSV genotype while the third sample contained a different ChiRSV genotype, with a sequence identity of 91.7% between the two. Using these sequences, we subsequently designed a pair of primers (forward 5' TGGGATAGAGCATCTGAGC 3' and reverse 5' GAGTCATTTAGGTCATAATCAGTTT 3') for specific amplification of ChiRSV but not ChiVMV by RT-PCR. A ChiRSV-specific 0.6-kb DNA fragment was amplified from 8 of the 14 samples. Sequencing of these amplicons confirmed the presence of ChiRSV in these samples. Flexuous, rod-shaped virus particles, typical of the potyviruses, were observed by electron microscopy in the virion preparations purified from chili plants infected only with ChiRSV. Virion protein was purified and subjected to analysis by the MALDI-TOF/TOF tandem mass spectrometer (BGI, Shenzhen, China), yielding 35 peptide fragments that share the highest sequence homology to the coat protein of Vietnamese ChiRSV C8 and C9 isolates (GenBank Accession Nos. ABL09413 and ABL09414) (1) with protein sequence coverage of 61.8% and 52.9%, respectively. On the basis of these data, we concluded that the chili plants in Hainan were infected with ChiRSV. This virus was first reported in Vietnam in 2008 (1) but has not been found elsewhere. Leaves of the chili plants infected only with the Hainan isolate of ChiRSV displayed green banding along the main and major lateral veins, light interveinal chlorosis, and crinkling, similar to the symptoms of ChiVMV previously reported in Hainan (2). However, ChiVMV-infected leaves were notably more distorted than those infected by ChiRSV. We did not observe the characteristic ringspots described on ChiRSV-infected chili peppers in Vietnam (1). The difference in the symptoms may be accounted for by different ChiRSV genotypes, chili varieties, or a combination of both. The finding of two distinct viruses causing similar symptoms will help to improve identification and management of viral diseases on chili peppers. References: (1) C. Ha et al. Arch. Virol. 153:45, 2008. (2) J. Wang et al. Plant Dis. 90:377, 2006.

Copper(II)-selective chelation improves function and antioxidant defences in cardiovascular tissues of rats as a model of diabetes: comparisons between triethylenetetramine and three less copper-selective transition-metal-targeted treatments

AIMS/HYPOTHESIS

Treatment with the Cu(II)-selective chelator triethylenetetramine (TETA) improves cardiovascular disease in human patients, and cardiac and vascular/renal disease in rats used as a model of diabetes. Here we tested two hypotheses: first, that TETA elicits greater improvement in organ function than less Cu-selective transition-metal-targeted treatments; second, that the therapeutic actions of TETA are consistent with mediation through suppression of oxidative stress.

METHODS

Rats were made diabetic with streptozotocin (55 mg/kg, i. v.) and treated from 8 weeks after disease induction for the following 8 weeks with effective dosages of oral TETA, or one of three less Cu-selective transition-metal-targeted treatments: D-penicillamine, deferiprone or Zn acetate. Treatment effects were measured in ex vivo cardiac and aortic tissues, plasma and urine.

RESULTS

Diabetes damaged both cardiac and renal/vascular function by impairing the ability of cardiac output to respond physiologically to rising afterload, and by significantly elevating the urinary albumin/creatinine ratio. Diabetes also lowered total antioxidant potential and heparan sulphate levels in cardiac and arterial tissues, and serum ferroxidase activity, whereas it elevated urinary heparan sulphate excretion. TETA treatment rectified or partially rectified all these defects, whereas the other three experimental treatments were ineffectual. By contrast, none of the four drug treatments lowered diabetes-mediated elevations of plasma glucose or lipid concentrations.

CONCLUSIONS/INTERPRETATION

TETA may limit the cardiac and renal/vascular damage inflicted by diabetes through its actions to reinforce antioxidant defence mechanisms, probably acting through selective chelation of 'loosely-bound'/chelatable Cu(II). It may also improve heparan sulphate homeostasis and bolster antioxidant defence by increasing vascular extracellular superoxide dismutase activity. Urinary albumin/creatinine ratio might prove useful for monitoring TETA treatment.

A copper(II)-selective chelator ameliorates diabetes-evoked renal fibrosis and albuminuria, and suppresses pathogenic TGF-beta activation in the kidneys of rats used as a model of diabetes

AIMS/HYPOTHESIS

The selective Cu(II) chelator triethylenetetramine (TETA) extracts systemic Cu(II) into the urine of diabetic humans and rats as a model of diabetes, and in the process also normalises hallmarks of diabetic heart disease. However, the role of Cu and its response to TETA in animals with diabetic nephropathy were previously unknown. Here, we report the effects of TETA treatment on Cu and other essential elements, as well as on indices of renal injury and known pathogenic molecular processes, in kidneys from a rat model of diabetes.

METHODS

Rats at 8 weeks after streptozotocin-induction of diabetes were treated with oral TETA (34 mg/day in drinking water) for a further 8 weeks and then compared with untreated diabetic control animals.

RESULTS

Renal tissue Cu was substantively elevated by diabetes and normalised by TETA, which also suppressed whole-kidney and glomerular hypertrophy without lowering blood glucose. The urinary albumin: creatinine ratio was significantly elevated in the rat model of diabetes but lowered by TETA. Total collagen was also elevated in diabetic kidneys and significantly improved by TETA. Furthermore, renal cortex levels of TGF-beta1, MAD homologue (SMAD) 4, phosphorylated SMAD2, fibronectin-1, collagen-III, collagen-IV, plasminogen activator inhibitor-1 and semicarbazide-sensitive amine oxidase all tended to be elevated in diabetes and normalised by TETA.

CONCLUSIONS/INTERPRETATION

Dysregulation of renal Cu homeostasis may be a key event eliciting development of diabetic nephropathy. Selective Cu(II) chelation can protect against pathogenic mechanisms that lead to or cause diabetic nephropathy and might be clinically useful in the treatment of early-stage diabetic kidney disease.

Selective albumin exchange: a novel and simple method to remove bilirubin

PURPOSE

Owing to its non-selectivity, plasma exchange has limited use in the treatment of patients with hepatic failure, although it is effective in removal of protein-bound toxins. This study reports a novel way to perform selective albumin exchange (SAE) by using a secondary plasma separator and aims to study its depurative capacity in the removal of bilirubin.

METHOD

In ex vivo experiments, the sieving coefficients (SCs) of plasma proteins for two secondary plasma separators, EC20W and EC30W (Asahi Medical, Tokyo, Japan), were measured. The EC20W membrane was chosen for use in clinical treatment because of its higher selectivity in separating albumin from plasma than the EC30W. The SCs of albumin, immunoglobumin G, A and M (IgG, IgA, IgM) for the EC20W were 0.3+/-0.021, 0.017+/-0.012, and 0, respectively. Five inpatients with plasma total bilirubin (TB) more than 200 micromol/L were enrolled in the present study and received a total of 10 SAE therapy sessions. Each session lasted 10 hours. SAE using the EC20W was conducted, making it similar to post-dilution continuous veno-venous hemofiltration (CVVH), with a filtrate rate of 2000 ml/h. Replacement fluid was composed by adding human albumin into conventional CVVH replacement fluid, with a final albumin concentration of 0.6%. During each treatment, the parameters of plasma and filtrate TB, direct bilirubin (DB), indirect bilirubin (IDB), and proteins were dynamically monitored. Hemostasis parameters were measured before and after sessions.

RESULTS

The reduction ratio of plasma TB, DB, and IDB after a single session was 29.1+/-3.0%, 31.3+/-4.5%, and 18.7+/-10.2%, respectively. The clearance of TB at initiation was 11.1+/-1.3 mL/min and declined to 4.4+/-0.5 ml/min at the end (p<0.01). This decline was accompanied by a reduction in albumin SC from 0.3+/-0.021 to 0.13+/-0.05. The molar ratio of bilirubin to albumin in filtrate was comparable to that in plasma. After a single treatment, plasma protein concentration including total protein, albumin, IgA and IgM remained unaffected, except for globulin and IgG, which were reduced by 11.5+/-7.8% and 11.1+/-2.3%, respectively. An improvement in hemostasis parameters, including plasma fibrinogen, prothrombase time and INR, was found after treatment. No obvious side effects were reported during any of the sessions.

CONCLUSION

Selective albumin exchange is a simple and effective method to remove bilirubin. However, further studies are required to verify its effects on clinical outcome.

Wedelolactone suppresses LPS-induced caspase-11 expression by directly inhibiting the IKK Complex

Caspase-11 is a key regulator of proinflammatory cytokine IL-1beta maturation and pathological apoptosis. Caspase-11 is not expressed in most tissues under normal condition, but highly inducible upon pathological stimulation such as in the presence of lipopolysaccharide (LPS). Here, we describe the identification and characterization of wedelolactone, a natural compound that inhibits LPS-induced caspase-11 expression in cultured cells by inhibiting NF-kappaB-mediated transcription. We demonstrate that wedelolactone is an inhibitor of IKK, a kinase critical for activation of NF-kappaB by mediating phosphorylation and degradation of IkappaBalpha.

[Effects and applications of ascorbic acid on the proliferation of Chlamydia trachomatis]

Two hundred and eighty-eight samples of patients with nongonococcal urethritis (NGU) and prostatitis were detected by cell culture and immunofluorescence assay for Chlamydia trachomatis (CT) and the effects of ascorbic acid(vitC) on the formation rate of inclusion of CT in positive samples were also studied. The results showed that the formation rate of inclusion of CT was 29.5% when the concentration of vitC was 5 micrograms.ml-1. The difference between test group and control group which contained cycloheximide in the media was insignificant (P > 0.05). The results suggested that vitC was a kind of nutrient needed for CT. The proliferation of CT in the cell can be promoted by vitC. We can replace cycloheximide by vitC in McCoy cell culture to detect clinic samples with CT.

Luciferase as a model for the site of inhaled anesthetic action

The in vivo potencies of anesthetics correlate with their capacity to suppress the reaction of luciferin with luciferase. In addition, luciferin has structural resemblances to etomidate. These observations raise the issues of whether luciferin, itself, might affect anesthetic requirement, and whether luciferase resembles the site of anesthetic action. Because the polar luciferin is unlikely to cross the blood-brain barrier (we found that the olive oil/water partition coefficient was 100 +/- 36 x 10(-7)), we studied these issues in rats by measuring the effect of infusion of luciferin in artificial cerebrospinal fluid into the lumbar subarachnoidal space and into the cerebral intraventricular space on the MAC (the minimum alveolar anesthetic concentration required to eliminate movement in response to a noxious stimulus in 50% of tested subjects) of isoflurane. MAC in rats given lumbar intrathecal doses of luciferin estimated to greatly exceed anesthetizing doses of etomidate, did not differ significantly from MAC in rats receiving only artificial cerebrospinal fluid into the lumbar intrathecal space. MAC slightly decreased when doses of luciferin estimated to greatly exceed anesthetizing doses of etomidate were infused intraventricularly (P < 0.05). In contrast to the absent or minimal effects of luciferin, intrathecal or intraventricular infusion of etomidate at similar or smaller doses significantly decreased isoflurane MAC. Luciferin did not affect +-aminobutyric acid type A or acetylcholine receptors expressed in Xenopus oocytes. These results suggest that luciferin has minimal or no anesthetic effects. It also suggests that luciferin/luciferase may not provide a good surrogate for the site at which anesthetics act, if this site is on the surface of neuronal cells.

IMPLICATIONS

In proportion to their potencies, anesthetics inhibit luciferin's action on luciferase, and luciferin structurally resembles the anesthetic etomidate. However, in contrast to etomidate, luciferin given intrathecally or into the third cerebral ventricle does not have anesthetic actions, and it does not affect +-aminobutyric acid or acetylcholine receptors in vitro. Luciferase may not provide a good surrogate for the site at which anesthetics act.

A retrospective study of continuous renal replacement therapy versus intermittent hemodialysis in severe acute renal failure

OBJECTIVE

To investigate the efficacy of continuous renal replacement therapy (CRRT) versus intermittent hemodialysis (IHD) in patients with severe acute renal failure (ARF).

METHODS

One hundred and ninety-three severe ARF patients who received renal support between December 1978 and December 1998 were involved in this study. Of them, 101 (52.3%) were treated with CRRT (CRRT group), and 92 (47.7%) with IHD (IHD group).

RESULTS

Sixty (59.4%) patients in the CRRT group got through the acute phase of disease and 41 (40.6%) patients did not survive while in the IHD group 59 (64.1%) patients survived and 33 (35.9%) patients did not. No significant difference in survival rate was found between the two groups. 24 of 64 patients (37.5%) in the CRRT group with multiple organ dysfunction syndrome (MODS) survived, while in the IHD group, 8 out of 44 (27.3%) survived, their survival rate was much lower than that in the CRRT group. Patients in CRRT group were more severely ill, as manifested by lower mean arterial pressure, higher APACHE II score, more dysfunctioned organs and requiring mechanical ventilation and vasopressor support as compared with patients in the IHD group, CRRT was found to improve hemodynamic stability with a better fluid balance and control of biochemical status, increased nutritional intake and a shorter duration of acute renal failure (P < 0.05).

CONCLUSION

CRRT perhaps may be the best choice in the treatment of severe ARF patients, for it can offer several distinct advantages compared to IHD. These may contribute to improving the survival rate of ARF patients, particularly those that are critically ill patients.

Site-specific incorporation of a phosphotyrosine mimetic reveals a role for tyrosine phosphorylation of SHP-2 in cell signaling

The regulation of protein tyrosine phosphatase (PTPase) SHP-2 is proposed to involve tyrosine phosphorylation on two tail tyrosine residues. Using "expressed protein ligation", nonhydrolyzable phosphotyrosine analogs were introduced at known phosphorylation sites in SHP-2. Biochemical analysis suggests that a phosphonate at Tyr542 interacts intramolecularly with the N-terminal SH2 domain to relieve basal inhibition of the PTPase, whereas a phosphonate at Tyr-580 stimulates the PTPase activity by interaction with the C-terminal SH2 domain. Microinjection experiments indicate that a single phosphorylation of Tyr-542 of SHP-2 is sufficient to activate the MAP kinase pathway in living cells. These studies support a novel mechanism explaining how tyrosine phosphorylation of a PTPase is important in signal transduction.

Blockade of AMPA receptors and volatile anesthetics: reduced anesthetic requirements in GluR2 null mutant mice for loss of the righting reflex and antinociception but not minimum alveolar concentration

BACKGROUND

The alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) subtype of glutamate receptor mediates fast excitatory neurotransmission in the central nervous system. Many general anesthetics inhibit AMPA receptors in vitro; however, it is not certain if this inhibition contributes to the behavioral properties of these drugs. AMPA receptors lacking the GluR2 subunit are resistant to blockade by barbiturates in vitro. Paradoxically, GluR2 null mutant (-/-) mice are more sensitive to barbiturate-induced loss of the righting reflex (LORR) compared with wild-type (+/+) littermates. To determine if interactions between anesthetics and AMPA receptors account for the increased sensitivity of (-/-) mice, the effects of volatile anesthetics that do not directly inhibit AMPA receptors were examined.

METHODS

Isoflurane, halothane, desflurane, or sevoflurane were administered to (-/-) and (+/+) littermate controls. Anesthetic requirements for LORR, movement to tail clamp (minimum alveolar concentration [MAC]), and hind-paw withdrawal latency (HPWL) were determined. Electrophysiologic methods examined the inhibition of AMPA receptors by isoflurane and halothane.

RESULTS

Anesthetic requirements for LORR and HPWL were decreased, whereas MAC values were unchanged in (-/-) mice. Isoflurane and halothane caused minimal inhibition of AMPA receptors at clinically relevant concentrations.

CONCLUSIONS

Direct blockade of AMPA receptors did not account for the increased sensitivity to volatile anesthetics in GluR2 null mutant mice for HPWL or LORR. Thus, the deficiency of GluR2-containing AMPA receptors increases the sensitivity of neuronal circuitry mediating these end points, but not MAC. GluR2-containing receptors do not contribute appreciably to MAC in this mouse model. These results illustrate the difficulties in attributing behavioral responses to drug-receptor interactions in genetically engineered animals.

[The effects of dialysate and ultrafiltration flow rate on solute clearance during continuous renal replacement therapy]

OBJECTIVE

To study the solute clearance during various forms of continuous renal replacement therapy(CRRT) and test the formulas that allow the prediction of the influence of dialysate and ultrafiltration flow rate on small solute removal during CRRT.

METHOD

Five patients with acute renal failure were included in the study and were treated by venovenous CRRT using the PRISMA predilution system. Solute clearance of urea nitrogen(UN), creatinine(Cr), uric acid(Ua), phosphate(P) and beta(2)-microglobulin(beta(2)-M) were evaluated during CRRT with different dialysates and ultrafiltration flow rates.

RESULTS

The determined clearance of small molecular solutes during continuous venovenous hemofiltration (CVVH) and continuous venovenous hemodialysis(CVVHD) was similar with the following formulas: K(UF) = (Q(UF)/60) x Q(B)/(Q(B) + Q(UF)/60) (in CVVH), Kd = Q(D)/60 (in CVVHD), where K is the clearance, Q(B), Q(D) and Q(UF) are blood, dialysate and ultrafiltration flow rates, respectively. There was very significant correlation between calculated values of K(UF) and observed clearances of small solutes such as UN, Cr, Ua and P during CVVH, between calculated values of Kd and observed clearances of UN, Cr, Ua but not P during CVVHD (P < 0.001). Clearances of UN, Cr, Ua and P during CVVHD were greater than those during CVVH, but clearance of beta(2)-M during CVVHD was less than that during CVVH. Interaction between convection and diffusion was found during continuous venovenous hemodiafiltration (CVVHDF).

CONCLUSIONS

The previous formulas can provide with the prediction of the clearance of small molecular solutes during CVVH and CVVHD. The present results demonstrate that diffusion is more efficient in removing small solutes than convection but less efficient in removing large solutes than convection. There is interaction between convection and diffusion during CVVHDF.

Ly-49W, an activating receptor of nonobese diabetic mice with close homology to the inhibitory receptor Ly-49G, recognizes H-2D(k) and H-2D(d)

The diversity and ligand specificity of activating Ly-49 receptors expressed by murine NK cells are largely unknown. We cloned a new Ly-49-activating receptor, expressed by NK cells of the nonobese diabetic mouse strain, which we have designated Ly-49W. Ly-49W is highly related to the known inhibitory receptor Ly-49G in its carbohydrate recognition domain, exhibiting 97.6% amino acid identity in this region. We demonstrate that the 4D11 and Cwy-3 Abs, thought to be Ly-49G specific, also recognize Ly-49W. Rat RNK-16 cells transfected with Ly-49W mediated reverse Ab-dependent cellular cytotoxicity of FcR-positive target cells, indicating that Ly-49W can activate NK-mediated lysis. We further show that Ly-49W is allo-MHC specific: Ly-49W transfectants of RNK-16 only lysed Con A blasts expressing H-2(k) or H-2(d) haplotypes, and Ab-blocking experiments indicated that H-2D(k) and D(d) are ligands for Ly-49W. Ly-49W is the first activating Ly-49 receptor demonstrated to recognize an H-2(k) class I product. Ly-49G and Ly-49W represent a new pair of NK receptors with very similar ligand-binding domains, but opposite signaling functions.

Fractional distillation of acid contaminants from sevoflurane

On two occasions, sevoflurane distributed for clinical practice has been found to be contaminated with compounds thought to include hydrogen fluoride (HF) and silicon tetrafluoride (SiF(4)). Both compounds can produce pulmonary injury. However, injury would require fractional distillation of the compounds during the course of sevoflurane vaporization. We hypothesized that such distillation would occur and that the compounds would vaporize more rapidly than would sevoflurane. Thus, we tested whether fractional distillation occurs during vaporization of sevoflurane containing HF or SiF(4), or from sevoflurane containing HF converted to other compounds by contact with glass. Vaporization of < 10% of the sevoflurane distilled 65%-99% of these compounds, SiF(4) distilling most rapidly, HF (converted to other acidic compounds, including SiF(4)) distilling nearly as rapidly, and HF slowest. Nuclear magnetic resonance studies indicated that HF interaction with glass changed all HF to three other compounds, one being SiF(4) and the others being unknown. HF and SiF4 distill from sevoflurane more rapidly than sevoflurane is vaporized. Measurement of acidity after sevoflurane administration may not reveal a previous presence of such contaminants.

Naturally occurring variability in anesthetic potency among inbred mouse strains

We measured the naturally occurring variability in anesthetic potency, defined by the minimum alveolar anesthetic concentrations (MACs) of inhaled anesthetics required to produce immobility in response to noxious stimuli, in seven widely used laboratory mouse strains. To these data, we added similar data for eight other mouse strains. The average MAC values for each anesthetic for the 15 strains were normally distributed, with a coefficient of variation (ratio of SD to mean) of 0.1. The range of MAC values was 39% for desflurane, 44% for isoflurane, and 55% for halothane. MAC values were highly reliable, with approximately 1% of the variance in MAC measurements for the strains being explained by measurement error. One hundred forty-six statistically significant differences among the 15 strains were found for the three inhaled anesthetics (isoflurane, desflurane, and halothane). Our results suggest that multiple genes underlie the observed variability in anesthetic potency.

IMPLICATIONS

Laboratory mouse strains differ significantly in susceptibility to anesthetics. These phenotypic differences may be exploited to help determine the genetic basis of anesthetic-induced immobility.

Mouse strain modestly influences minimum alveolar anesthetic concentration and convulsivity of inhaled compounds

In this study, we measured the minimum alveolar anesthetic concentration (MAC) in several mouse strains, including strains used in the construction of genetically engineered mice. This is important because defined genetic modifications are used increasingly to test mechanisms of inhaled anesthetic action, and background variability in MAC can potentially influence the interpretation of these studies. We investigated the effect of strain on MAC for desflurane, isoflurane, halothane, ethanol, the experimental anesthetic 1-chloro-1,2,2-trifluorocyclobutane, and convulsive 50% effective dose (the dose required to produce convulsions in 50% of animals) of the nonimmobilizer 1,2-dichlorohexafluorocyclobutane. These drugs were studied in eight inbred strains, including both laboratory and wild mouse strains (129/J, 129/SvJ, 129/Ola Hsd, C57BL/6NHsd, C57BL/6J, DBA/2J, Spret/Ei, and Cast/Ei), one hybrid strain (B6129F2/J, derived from the C57BL/6J and 129/J strains), and one outbred strain (CD-1). To test our ability to detect effects in a genetically modified mouse, we compared these data with those for a mouse lacking the gamma (neuronal) isoform of the protein kinase C gene (PKCgamma). We also assessed whether amputating the tail tip of mice (a standard method of obtaining tissue for genetic analysis) increased MAC (e.g., by sensitization of the spinal cord). MAC and convulsant 50% effective dose values differed modestly among strains, with a range of 17% to 39% from the lowest to highest values for MAC using conventional anesthetics, and up to 48% using the experimental anesthetic 1-chloro-1,2,2-trifluorocyclobutane. Convulsivity to the nonimmobilizer varied by 47%. Amputating the tail tip did not affect MAC. PKCgamma knockout mice had significantly higher MAC values than control animals for isoflurane, but not for halothane or desflurane, which implies that protein phosphorylation by PKCgamma can alter sensitivity to isoflurane.

IMPLICATIONS

Anesthetic potency differs by modest amounts among inbred, outbred, wild, and laboratory mouse strains. Absence of the neural form of protein kinase C increases minimum alveolar anesthetic concentration for isoflurane, indicating that protein phosphorylation by the gamma-isoform of protein kinase C (PKCgamma) can influence the potency of this anesthetic.

Polyhalogenated methyl ethyl ethers: solubilities and anesthetic properties

The several potent inhaled anesthetics released for clinical use in the past four decades have been halogenated ethers, and, with one exception, methyl ethyl ethers. In the present report, we detail some structural and physical properties associated with anesthetic potency in 27 polyhalogenated methyl ethyl ethers. We obtained new data for 22 compounds. We used response/nonresponse of rats to electrical stimulation of the tail as the anesthetic end point (i.e., we measured the minimum alveolar anesthetic concentration [MAC]). For compounds that did not produce anesthesia when given alone (they only produced excitation/convulsions), we studied MAC by additivity studies with desflurane. We obtained MAC values for 20 of 22 of the studied ethers, which gave products of MAC x oil/gas partition coefficient ranging from 1.27 to 18.8 atm, compared with a product of 1.82+/-0.56 atm for conventional inhaled anesthetics. Despite solubilities in olive oil and application of partial pressures predicted by the Meyer-Overton hypothesis to provide anesthesia, 2 of 22 ethers (CCIF2OCCIFCF3 and CCIF2OCF2CClF2) had no anesthetic (immobilizing) effect when given alone, did not decrease the anesthetic requirement for desflurane, and had excitatory properties when administered alone. As with other inhaled anesthetics, anesthetic potency seemed to correlate with both polar and nonpolar properties. These ethers, representing structural analogs of currently used clinical volatile anesthetics, may be useful in identifying and understanding the mechanisms by which inhaled anesthetics act.

IMPLICATIONS

The several potent, inhaled, polyhalogenated methyl ethyl ether anesthetics released for clinical use in the past four decades seem to have specific useful characteristics that set them apart from other methyl ethyl ethers. Properties of this class of compounds have implications for the future development of anesthetics and the mechanisms by which they act.

Minimum alveolar anesthetic concentration of fluorinated alkanols in rats: relevance to theories of narcosis

The Meyer-Overton hypothesis predicts that the potency of conventional inhaled anesthetics correlates inversely with lipophilicity: minimum alveolar anesthetic concentration (MAC) x the olive oil/gas partition coefficient equals a constant of approximately 1.82 +/- 0.56 atm (mean +/- SD), whereas MAC x the octanol/gas partition coefficient equals a constant of approximately 2.55 +/- 0.65 atm. MAC is the minimum alveolar concentration of anesthetic required to eliminate movement in response to a noxious stimulus in 50% of subjects. Although MAC x the olive oil/gas partition coefficient also equals a constant for normal alkanols from methanol through octanol, the constant (0.156 +/- 0.072 atm) is one-tenth that found for conventional anesthetics, whereas the product for MAC x the octanol/gas partition coefficient (1.72 +/- 1.19) is similar to that for conventional anesthetics. These normal alkanols also have much greater affinities for water (saline/gas partition coefficients equaling 708 [octanol] to 3780 [methanol]) than do conventional anesthetics. In the present study, we examined whether fluorination lowers alkanol saline/gas partition coefficients (i.e., decreases polarity) while sustaining or increasing lipid/gas partition coefficients, and whether alkanols with lower saline/gas partition coefficients had products of MAC x olive oil or octanol/gas partition coefficients that approached or exceeded those of conventional anesthetics. Fluorination decreased saline/gas partition coefficients to as low as 0.60 +/- 0.08 (CF3[CF2]6CH2OH) and, as hypothesized, increased the product of MAC x the olive oil or octanol/gas partition coefficients to values equaling or exceeding those found for conventional anesthetics. We conclude that the greater potency of many alkanols (greater than would be predicted from conventional inhaled anesthetics and the Meyer-Overton hypothesis) is associated with their greater polarity.

IMPLICATIONS

Inhaled anesthetic potency correlates with lipophilicity, but potency of common alkanols is greater than their lipophilicity indicates, in part because alkanols have a greater hydrophilicity--i.e., a greater polarity.

Nonimmobilizers and transitional compounds may produce convulsions by two mechanisms

Some inhaled compounds cause convulsions. To better appreciate the physical basis for this property, we correlated the partial pressures that produced convulsions in rats with the lipophilicity (nonpolarity) and hydrophilicity (polarity) of 45 compounds: 3 n-alkanes, 18 n-haloalkanes, 3 halogenated aromatic compounds, 3 cycloalkanes and 3 halocycloalkanes, 13 halogenated ethers, and 2 noble gases (He and Ne). In most cases, convulsions were quantified by averaging the alveolar partial pressures just below the pressures that caused and slightly higher pressures that did cause clonic convulsions (ED50). The ED50 did not correlate with hydrophilicity (the saline/gas partition coefficient), nor was there an obvious correlation with molecular structure. For 80% of compounds (36 of 45), the ED50 correlated closely (r2 = 0.99) with lipophilicity (the olive oil/gas partition coefficient). Perhaps because they block the effect of GABA on GABA(A) receptors, five compounds were more potent than would be predicted from their lipophilicity. Conversely, four compounds may have been less potent than would be predicted because they (like conventional inhaled anesthetics) enhance the effect of GABA on GABA(A) receptors.

IMPLICATIONS

Nonimmobilizers and transitional compounds may produce convulsions by two mechanisms. One correlates with lipophilicity (nonpolarity), and the other correlates with an action on GABA(A) receptors.

Rat strain minimally influences anesthetic and convulsant requirements of inhaled compounds in rats

We assessed the effect of rat strain on susceptibility to anesthesia and convulsions produced by inhaled compounds. We determined the minimum alveolar anesthetic concentration (MAC) of desflurane and nitrous oxide, and the convulsive 50% effective dose (ED50) of 1,2-dichlorohexafluorocyclobutane, flurothyl, and difluoromethyl-1-chlorotetrafluoroethyl ether in five strains (three inbred [Long Evans, Sprague-Dawley, and Wistar] and two outbred [Fischer and Brown Norway]). Strain had slight effects on anesthetic potency, the strains with the highest MAC values (Long Evans and Brown Norway) having values < or =28% greater than the strains with the lowest values (Sprague Dawley and Wistar). MAC for nitrous oxide correlated directly with MAC for desflurane as a function of strain. MAC for either desflurane or nitrous oxide correlated inversely with the convulsive ED50 of 1,2-dichlorohexafluorocyclobutane, but correlated poorly (and directly) with the convulsive ED50 of the remaining compounds. Convulsivity varied little as a function of strain (greatest difference 21%) and did not vary consistently as a function of strain. No consistent difference was seen between inbred versus outbred strains.

IMPLICATIONS

Rat strain has a minimal effect on the potency of inhaled anesthetics or the convulsant activity of inhaled compounds. It seems that the sites acted on by inhaled compounds to produce anesthesia and convulsions are conserved across common rat strains.

Minimum alveolar concentrations of noble gases, nitrogen, and sulfur hexafluoride in rats: helium and neon as nonimmobilizers (nonanesthetics)

We assessed the anesthetic properties of helium and neon at hyperbaric pressures by testing their capacity to decrease anesthetic requirement for desflurane using electrical stimulation of the tail as the anesthetic endpoint (i.e., the minimum alveolar anesthetic concentration [MAC]) in rats. Partial pressures of helium or neon near those predicted to produce anesthesia by the Meyer-Overton hypothesis (approximately 80-90 atm), tended to increase desflurane MAC, and these partial pressures of helium and neon produced convulsions when administered alone. In contrast, the noble gases argon, krypton, and xenon were anesthetic with mean MAC values of (+/- SD) of 27.0 +/- 2.6, 7.31 +/- 0.54, and 1.61 +/- 0.17 atm, respectively. Because the lethal partial pressures of nitrogen and sulfur hexafluoride overlapped their anesthetic partial pressures, MAC values were determined for these gases by additivity studies with desflurane. Nitrogen and sulfur hexafluoride MAC values were estimated to be 110 and 14.6 atm, respectively. Of the gases with anesthetic properties, nitrogen deviated the most from the Meyer-Overton hypothesis.

IMPLICATIONS

It has been thought that the high pressures of helium and neon that might be needed to produce anesthesia antagonize their anesthetic properties (pressure reversal of anesthesia). We propose an alternative explanation: like other compounds with a low affinity to water, helium and neon are intrinsically without anesthetic effect.

Circuit absorption of halothane, isoflurane, and sevoflurane

Uptake of inhaled anesthetics may be measured as the amount of anesthetic infused to maintain a constant alveolar concentration of anesthetic. This method assumes that the patient absorbs all of the infused anesthetic, and that none is lost to circuit components. Using a standard anesthetic circuit with a 3-L rebreathing bag simulating the lungs, and simulating metabolism by input of carbon dioxide, we tested this assumption for halothane, isoflurane, and sevoflurane. Our results suggest that after washin of anesthetic sufficient to eliminate a material difference between inspired and end-tidal anesthetic, washin to other parts of the circuit (probably the ventilator) and absorbent (soda lime) continued to remove anesthetic for up to 15 min. From 30 min to 180 min of anesthetic administration, circuit components absorbed trivial amounts of isoflurane (12 +/- 13 mL vapor at 1.5 minimum alveolar anesthetic concentration, slightly more sevoflurane (39 +/- 15 mL), and still more halothane (64 +/- 9 mL). During this time, absorbent degraded sevoflurane (321 +/- 31 mL absorbed by circuit components and degraded by soda lime). The amount degraded increased with increasing input of carbon dioxide (e.g., the 321 +/- 31 mL increased to 508 +/- 48 mL when carbon dioxide input increased from 250 mL/min to 500 mL/min). Measurement of anesthetic uptake as a function of the amount of anesthetic infused must account for these findings.

IMPLICATIONS

Systems that deliver inhaled anesthetics may also remove the anesthetic. Initially, anesthetics may diffuse into delivery components and the interstices of material used to absorb carbon dioxide. Later, absorbents may degrade some anesthetics (e.g., sevoflurane). Such losses may compromise measurements of anesthetic uptake.

The effect of anesthetic duration on kinetic and recovery characteristics of desflurane versus sevoflurane, and on the kinetic characteristics of compound A, in volunteers

This study documents the differences in kinetics of 2 h (n = 7) and 4 h (n = 9) of 1.25 minimum alveolar anesthetic concentration (MAC) of desflurane (9.0%) versus (on a separate occasion) sevoflurane (3.0%), both administered in a fresh gas inflow of 2 L/min. These data are extensions of our previous 8-h (n = 7) studies of these anesthetics. By 10 min of anesthetic administration, average inspired (F(I)) and end-tidal concentration (F(A)) (F(I)/F(A); the inverse of the more commonly used F(A)/F(I)) decreased to less than 1.15 for both anesthetics, with the difference from 1.0 nearly twice as great for sevoflurane as for desflurane. During all sevoflurane administrations, F(A)/F(I) for Compound A [CH2F-O-C(=CF2) (CF3); a vinyl ether resulting from the degradation of sevoflurane by Baralyme] equaled approximately 0.8, and the average inspired concentration equaled approximately 40 ppm. Compound A is of interest because at approximately 150 ppm-h, it can induce biochemical and histological evidence of glomerular and tubular injury in rats and humans. During elimination, F(A)/F(A0) for Compound A (F(A0) is the last end-tidal concentration during anesthetic administration) decreased abruptly to 0 after 2 h and 4 h of anesthesia and to approximately 0.1 (F(A) approximately 3 ppm) after 8 h of anesthesia. In contrast, F(A)/F(A0) for desflurane and sevoflurane decreased in a conventional, multiexponential manner, the decrease being increasingly delayed with increasing duration of anesthetic administration. F(A)/F(A0) for sevoflurane exceeded that for desflurane for any given duration of anesthesia, and objective and subjective measures indicated a faster recovery with desflurane. Times (mean +/- SD) to initial response to command (2 h 10.9 +/- 1.2 vs 17.8 +/- 5.1 min, 4 h 11.3 +/- 2.1 vs 20.8 +/- 4.8 min, 8 h 14 +/- 4 vs 28 +/- 8 min) and orientation (2 h 12.7 +/- 1.6 vs 21.2 +/- 4.6 min, 4 h 14.8 +/- 3.1 vs 25.3 +/- 6.5 min, 8 h 19 +/- 4 vs 33 +/- 9 min) were shorter with desflurane. Recovery as defined by the digit symbol substitution test, P-deletion test, and Trieger test results was more rapid with desflurane. The incidence of vomiting was greater with sevoflurane after 8 h of anesthesia but not after shorter durations. We conclude that for each anesthetic duration, F(I) more closely approximates F(A) with desflurane during anesthetic administration, F(A)/F(A0) decreases more rapidly after anesthesia with desflurane, and objective measures indicate more rapid recovery with desflurane. Finally, it seems that after 2-h and 4-h administrations, all Compound A taken up is bound within the body.

IMPLICATIONS

Regardless of the duration of anesthesia, elimination is faster and recovery is quicker for the inhaled anesthetic desflurane than for the inhaled anesthetic sevoflurane. The toxic degradation product of sevoflurane, Compound A, seems to bind irreversibly to proteins in the body.