Effectiveness and safety of implementing an enhanced patient comfort programme for elective neurosurgical patients: a randomised controlled trial protocol.

INTRODUCTION: Patient comfort is an important quality indicator of healthcare. According to Kolcaba's comfort theory, enhanced comfort is achieved by meeting the needs in four contexts: physical, psychospiritual, sociocultural and environmental. An enhanced patient comfort (EPC) programme based on this theory has been designed for elective neurosurgical patients. This study aims to assess its feasibility, effectiveness and safety. METHODS AND ANALYSIS: The EPC programme patients will be evaluated in a single institutional randomised controlled trial. A total of 110 patients admitted for elective neurosurgery (including craniotomy, endoscopic trans-sphenoidal surgery and spine surgery) will be randomised in a 1:1 ratio to two groups. Patients in the EPC group are managed under the newly developed EPC programme, which aims to enhance patient experience and includes care coordination since admission (such as appointment of a care support coordinator, personalised setting, and cultural and spiritual support), preoperative management (such as lifestyle intervention, potential psychological and sleep intervention, and prerehabilitation), intraoperative and anaesthetic management (such as nurse coaching, music playing, and pre-emptive warming), postoperative management (such as early extubation, early diet advancement, mood and sleep management, and early ambulation) and optimised discharge planning; while those in the control group receive conventional perioperative care. The primary outcome is patient satisfaction and comfort measured by the Chinese Surgical Inpatient Satisfaction and Comfort Questionnaire. The secondary outcomes include postoperative morbidity and mortality, postoperative pain score, postoperative nausea and vomiting, functional recovery status (Karnofsky performance status and Quality of Recovery-15 score), mental status (anxiety and depression), nutritional status, health-related quality of life, hospital length of stay, reoperation and readmission rates, overall cost and patient experience. ETHICS AND DISSEMINATION: Ethical approval to conduct the study has been obtained from Institutional Review Board of Xi'an International Medical Center (No. 202028). The results will be presented at scientific meetings and published in peer-reviewed journals. TRIAL REGISTRATION NUMBER: Chinese clinical trial registry ChiCTR2000039983.

Dexmedetomidine attenuates hippocampal neuroinflammation in postoperative neurocognitive disorders by inhibiting microRNA-329-3p and activating the CREB1/IL1RA axis.

RATIONALE: Due to its anti-inflammatory effect, dexmedetomidine (DEX) can confer neuroprotection in postoperative neurocognitive disorders (NCD). Here, the mechanism responsible for this effect of DEX is rarely ascertained. OBJECTIVES: Our research was implemented to figure out mechanism governing the protection of DEX against hippocampal neuroinflammation in postoperative NCD. METHODS: Exploratory laparotomy was applied for generating a postoperative NCD mouse model before bilateral hippocampal injection with microRNA (miR)-329-3p-agomir and intraperitoneal injection with DEX. Cognitive function of mice was evaluated by water maze test and fear conditioning test. Immunofluorescence was performed to assess microglial activation in hippocampus. After cell transfection and DEX treatment, mouse microglial cells (BV-2) were stimulated by lipopolysaccharide (LPS). IL-1ß, IL-6, and TNF-α levels and the number of phagocytes were assessed by ELISA and flow cytometry. Dual-luciferase reporter assay was adopted to assess the relationship between miR-329-3p and CREB1. RESULTS: miR-329-3p expression was reduced in the postoperative NCD mice after DEX treatment. DEX treatment or miR-329-3p downregulation caused attenuated cognitive dysfunction and microglia activation as well as reduced IL-1ß, IL-6, and TNF-α levels in the hippocampus of the postoperative NCD mice. Mechanistically, miR-329-3p inversely targeted CREB1 that activated IL1RA in LPS-induced BV-2 cells. DEX treatment, miR-329-3p inhibition, or CREB1 or IL1RA upregulation curtailed the release of proinflammatory proteins and the number of phagocytes in LPS-induced BV-2 cells. CONCLUSIONS: Collectively, our data provided the novel insight of the neuroprotective mechanism of DEX in postoperative NCD pertaining to the miR-329-3p/CREB1/IL1RA axis.

A novel time-resolved fluoroimmunoassay based on magnetic microspheres method for detecting antibodies against the phospholipase A2 receptor.

BACKGROUND: the level of serum antibodies against the M-type phospholipase A2 receptor (anti-PLA2R-IgG) is closely related to the disease activity of idiopathic membranous nephropathy (IMN). Therefore, the establishment of a sensitive and rapid method for detecting anti-PLA2R-IgG will be beneficial for the differential diagnosis of IMN. METHODS: magnetic microspheres coupled with the PLA2R antigen were used to capture anti-PLA2R-IgG in serum samples, and europium-labeled goat anti-human IgG antibodies were used for tracking. An anti-PLA2R-IgG-time-resolved fluoroimmunoassay (TRFIA) based on magnetic microspheres using an indirect method was established and analyzed. Various indicators of this method were evaluated. RESULTS: the sensitivity of the anti-PLA2R-IgG-TRFIA based on magnetic microspheres was 0.51 RU mL-1, and the linear detection range was 0.51-1000 RU mL-1. The average intra- and inter-assay coefficients of variation (CVs) were 3.62% and 4.45%, respectively, and the average recovery was 95.60%. No cross-reactivity with IgA was observed. The median (interquartile range) concentration of anti-PLA2R-IgG in patients with IMN was 40.37 RU mL-1 (11.33 to 83.05 RU mL-1). The cut-off values of the anti-PLA2R-IgG concentration for healthy volunteers and those with other kidney diseases were determined to be 8.06 RU mL-1 and 13.23 RU mL-1, respectively. Additionally, the positive rates of anti-PLA2R-IgG in patients with IMN corresponding to the above cut-off values were 91.07% and 71.32%, respectively. The correlation coefficient between the magnetic microsphere-based anti-PLA2R-TRFIA and the PLA2R-ELISA kit for detecting anti-PLA2R-IgG was 0.944. CONCLUSION: a highly sensitive and rapid magnetic microsphere-based anti-PLA2R-IgG-TRFIA was successfully established to detect the concentrations of anti-PLA2R-IgG in the sera of patients with IMN.

Establishment of time-resolved fluoroimmunoassay of IgG4 based on magnetic microspheres.

BACKGROUND: The abnormal increase in serum IgG4 level is an important clinical symptom of IgG4-related disease (IgG4-RD), and the detection of serum IgG4 level is a powerful tool for the diagnosis of IgG4-RD. This study was conducted to establish a simple and rapid immunoassay for the determination of human serum IgG4 levels. METHODS: Based on the competition method, a novel immunoassay was established for the determination of human serum IgG4 using a combination of time-resolved fluoroimmunoassay (TRFIA) and magnetic microspheres. IgG4 was coupled with magnetic microspheres and competed with IgG4 in the samples to bind the Eu3+ -labeled anti-IgG4 antibody. The immunocomplex was separated and washed in a magnetic field, and the fluorescence counts were measured according to the number of dissociated europium ions. RESULTS: The analytical sensitivity of IgG4-TRFIA based on magnetic microspheres was 0.006 g/L, and the detection range was 0.006-20 g/L under optimal conditions. The precision, recovery, and specificity of this immunoassay were demonstrated to be acceptable. The clinical application of IgG4-TRFIA based on magnetic microspheres was evaluated and compared with that of immunonephelometry. The results showed that the two detection methods had a good correlation, with a correlation coefficient of .9871. CONCLUSION: IgG4-TRFIA based on magnetic microspheres has the advantages of high sensitivity, wide detection range, and short analysis time and has the potential to become a useful tool for the diagnosis of IgG4-RD.

Endoscopic Endonasal Transsphenoidal Approach for Third Ventriculostomy in the Management of Obstructive Hydrocephalus.

ABSTRACT: Endoscopic third ventriculostomy (ETV) is a safe and effective method for the management of obstructive hydrocephalus. Traditional approach is a transfrontal trajectory through the foramen of Monro to access and open the third ventricle floor. Though endoscopic endonasal transsphenoidal approach (EETA) for pituitary and skull base tumors has become increasingly popular, no published literature has explored its utility in performing an ETV. Here, the authors reported a successful ETV for obstructive hydrocephalus through the EETA. A 57-year-old male presenting with progressive headache and gait disturbance for 3 months was diagnosed with obstructive hydrocephalus. Brain MRI revealed an obstruction of cerebrospinal fluid (CSF) flow at the cerebral aqueduct and supratentorial hydrocephalus, accompanied with dilatation and downward herniation of the third ventricle floor. Considering the displacement of the third ventricle floor and the indication for surgery, an ETV was successfully performed through the EETA. No postoperative complication was observed. Both radiological and clinical evaluation postoperatively confirmed ETV success with decreased ventricular size, increased CSF flow across the floor of the third ventricle, and improved clinical signs. EETA is a feasible approach for ETV in selected cases of obstructive hydrocephalus. This approach provides a short trajectory to directly visualize and open the Liliequist's membrane and the displaced floor of the third ventricle, while minimizes damage to normal brain tissue. Skull base repair with nasoseptal flap ensures the success rate by preventing postoperative CSF leak and infection.

Doxorubicin hydrochloride enhanced antitumour effect of CEA-regulated oncolytic virotherapy in live cancer cells and a mouse model.

Oncolytic adenovirus (OA) has attracted increasing attention due to their specific proliferation in tumour cells and resulting in lysis of tumour cells. To further improve the antitumour effect of OA, in this study, we combined CD55-TRAIL-IETD-MnSOD (CD55-TMn), a CEA-controlled OA constructed previously, and chemotherapy to investigate their synergistic effect and possible mechanisms. MTT assay was performed to detect antitumour effects. Hoechst 33 342 and flow cytometric analysis were used to examine cell apoptosis. Western blotting was performed to examine cell pyroptosis and apoptosis mechanism. Animal experiment was used to detect antitumour effect of doxorubicin hydrochloride (Dox) combined with CD55-TMn in vivo. We firstly found that Dox promotes gene expression mediated by CEA-regulated OA and virus progeny replication by activating phosphorylation of Smad3, and Dox can enhance antitumour effect of CEA-regulated CD55-TMn by promoting cell apotopsis and cell pyroptosis. Thus, our results provide an experimental and theoretical basis on tumour therapy by combination treatment of the oncolytic virotherapy and chemotherapy and it is expected to become a novel strategy for liver cancer therapy.

Management of Postoperative Pain after Elective Craniotomy: A Prospective Randomized Controlled Trial of a Neurosurgical Enhanced Recovery after Surgery (ERAS) Program.

Objective: To prospectively evaluate the efficacy of a neurosurgical enhanced recovery after surgery (ERAS) protocol on the management of postoperative pain after elective craniotomies. Methods: This randomized controlled trial was conducted in the neurosurgical center of Tangdu Hospital (Fourth Military Medical University, Xi'an, China). A total of 129 patients undergoing craniotomies between October 2016 and July 2017 were enrolled in a randomized clinical trial comparing an ERAS protocol to a conventional postoperative care regimen. The primary outcome was the postoperative pain score assessed by a verbal numerical rating scale (NRS). Results: Patients in the ERAS group had a significant reduction in their postoperative pain scores on POD 1 compared to patients in the control group (p < 0.05). More patients (n = 44, 68.8%) in the ERAS group experienced mild pain (NRS: 1 to 3) on POD1 compared with patients (n = 23, 35.4%) in the control group (p < 0.05). A further reduction in pain scores was also observed on POD 2 and maintained on POD 3 in the ERAS group compared with that in the control group. In addition, the median postoperative length of hospital stay was significantly decreased with the incorporation of the ERAS protocol compared to controls (ERAS: 4 days, control: 7 days, P<0.001). Conclusion: The implementation of a neurosurgical ERAS protocol for elective craniotomy patients has significant benefits in alleviating postoperative pain and enhancing recovery leading to early discharge after surgery compared to conventional care. Further evaluation of this protocol in larger, multi-center studies is warranted.

Cumulative Live Birth Rates After the First ART Cycle Using Flexible GnRH Antagonist Protocol vs. Standard Long GnRH Agonist Protocol: A Retrospective Cohort Study in Women of Different Ages and Various Ovarian Reserve.

Objective: To compare the cumulative live birth rates (cLBRs) after the first assisted reproductive technology (ART) cycle using flexible gonadotropin releasing hormone (GnRH)-antagonist protocol vs. standard long GnRH agonist protocol for controlled ovarian stimulation (COS) in infertile women with different ages and ovarian reserve. Methods: Women who underwent ART treatment at our center between June 1st, 2015 and December 31st, 2018 were screened. Among them, only women who underwent their first COS cycle with flexible GnRH antagonist protocol or standard long GnRH agonist protocol were included in this study. The main outcome measurement was cLBR. Results: A total of 4,402 patients were eligible for the analysis, of whom, 2,762 patients used the GnRH agonist protocol and 1,640 patients used the GnRH antagonist protocol. The cLBRs of women in the antagonist protocol group and long agonist protocol group were 45.3 and 50.0%, respectively. Subgroup multivariable regression analysis showed that, in patients with low ovarian reserve (AFC ≤ 7), the cLBR was significantly lower in the antagonist group than in the long agonist protocol group [OR (95% CI) 0.62 (0.41, 0.94)], which effect was more robust in younger patients (<30 y) [OR (95% CI) 0.29 (0.11, 0.74)]. The analysis also revealed remarkably lower cLBR in patients above 40 years regardless of their AFC, although the difference was not statistically significant. However, in patients with high ovarian reserve (AFC >24), the cLBR was higher in cycles with antagonist protocol than with the long agonist protocol [OR (95% CI) 1.43 (0.96, 2.12)], and the effect was of statistical significance in younger patients (< 30 y) [OR (95% CI) 1.78 (1.07, 2.96)]. Conclusion: The present study suggests that the flexible GnRH antagonist protocol might not be suitable for patients with low ovarian reserve (AFC ≤ 7) or patients aged over 40 years. However, flexible GnRH antagonist protocol might be strongly recommended for patients under 30 years old and with high ovarian reserve (AFC > 24). For the rest groups of patients in the present cohort, antagonist protocol was slightly favored because it had lower OHSS in general and in patients with poly-cystic ovarian syndrome (PCOS) according to previous publications.

Preconditioning with hydrogen sulfide ameliorates cerebral ischemia/reperfusion injury in a mouse model of transient middle cerebral artery occlusion.

Ischemic stroke and reperfusion injury are a common and serve medical situation in the elderly population. H2S is a gas neuromodulator which also possesses anti-oxidant and anti-inflammatory properties, and is found to play neuroprotective effect in neurodegenerative diseases. This study investigated the effect of endogenous and exogenous H2S in a mouse model of ischemic stroke. 129P2-Cbstm1Unc/J mice with heterozygous mutants in H2S generating enzyme cystathionine ß-synthase were used to study the effect of endogenous H2S. H2S donor NaHS was used as exogenous H2S. Animals were pretreated with H2S and then subjected to middle cerebral artery occlusion surgery. Behavioral outcome was evaluated by novel object recognition test. Inflammatory cytokines were measured using ELISA. Western blot was used to detect the activation of NF-κB. Aged 129P2-Cbstm1Unc/J mice showed exaggerated inflammation and more severe cognitive impairment after ischemia, while exogenous H2S treatment inhibited inflammation and attenuated behavioral impairment. The anti-inflammatory effect of H2S was mediated by inhibiting NF-κB. Our findings suggest that both endogenous and exogenous H2S are involved in the neuroprotection against ischemia/reperfusion-induced cerebral injury.

Developmental toxicity and alteration of gene expression in zebrafish embryo exposed to 6-benzylaminopurine.

6-benzylaminopurine (6-BA) is widely used in agriculture and horticulture as plant growth regulator. Its excessive use may pose a potential risk to both environment and human health, which is causing great concern. This study was undertaken to assess the acute developmental toxicity of 6-BA to zebrafish embryos based on OECD protocols and mortality, hatching rate and malformation were investigated. Results showed that the 96 h-LC50 and 96 h- EC50 values were 63.29 mg/L and 41.86 mg/L, respectively. No mortality or teratogenic effects were found at concentrations lower than 10 mg/L 6-BA at concentrations higher than 50 mg/L significantly inhibited hatchability and embryo development, induced serious toxicity characterized by morphologic abnormalities (elongated pericardium, heart and yolk sac edema, spine curvature) and functional failure (slow spontaneous movement and heart rate, growth retardation, yolk sac absorption retention). Moreover, 6-BA-induced apoptosis was observed in embryos by the acridine orange staining and confirmed by the apoptotic-related genes, all of which p53 was significantly up-regulated at concentrations higher than 10 mg/L, bax at concentrations higher than 12.5 mg/L, while bcl2 was down-regulated at concentrations higher than 25 mg/L. As for genes of cardiac development, qPCR results demonstrated that nkx2.5, gata5, and amhc were significantly down-regulated at concentrations higher than 25 mg/L, vmhc and atp2a2a at concentration of 50 mg/L, in contrast, hand2 was up-regulated at concentration of 50 mg/L. Our data indicate that 6-BA induces a dose-dependent toxicity resulting in apoptosis through the involvement of p53-dependent pathways and hindering normal heart development in zebrafish embryos.

Oncolytic viro-chemotherapy exhibits antitumor effect in laryngeal squamous cell carcinoma cells and mouse xenografts.

Background: Oncolytic virus can specifically replicate in and then lyse tumor cells, but seldom in normal cells. Further studies have shown the significant therapeutic effect of oncolytic virotherapy combining with other strategies, such as chemo-, radio-, and immunotherapy et al. In this study, we investigated the combinational effect of oncolytic virus ZD55-TRAIL and chemotherapy drug doxorubicin (DOX) on human laryngeal squamous cell carcinoma (LSCC). Methods: The effect of ZD55-TRAIL combined with DOX on cell growth was assessed in LSCC Hep2 cells and normal cells by MTT assay. Hochest 33342 staining was performed to observe cell morphological changes. Western blot was used to detect the expression of apoptotic activation proteins. The in vivo antitumor efficacy of combination treatment was estimated in laryngeal cancer xenograft models. Results: The combination of ZD55-TRAIL and DOX exhibited enhanced inhibitory effects on laryngocarcinoma cell growth, and had few side effects to normal cells in vitro. Chemotherapy drug increased the inducement of tumor cell apoptosis mediated by oncolytic virus. In vivo experiment confirmed that the combination treatment significantly inhibited Hep2 laryngocarcinoma xenografts growth in mice. Conclusion: The oncolytic viro-chemotherapy is a potent therapeutic approach for in vitro cytotoxicity evaluation of Hep2 cells and xenograft growth in vivo.

GOLPH2-regulated oncolytic adenovirus, GD55, exerts strong killing effect on human prostate cancer stem-like cells in vitro and in vivo.

GOLPH2 (also called GP73) is a Golgi glycoprotein, which has been identified as a novel tumor marker upregulated in various cancers, including prostate cancer (PCa). GD55 is a novel GOLPH2-regulated oncolytic adenovirus that exhibits a strong killing effect on hepatoma cells. Here, we investigate the antitumor effect of GD55 on prostate cancer stem cell (CSC)-like cells in vitro and in vivo. Prostate CSC-like sphere cells were acquired and enriched by culturing DU145, LNCap or P3 prostate cancer cells in suspension. The prostate CSC-like sphere cells were capable of self-renewal, differentiation and quiescence, displaying tumorigenic feature and chemo-resistance to 5-FU, doxorubicin and DDP. Treatment with GD55 (1, 5, 10 MOI) dose-dependently suppressed the viability of DU145 sphere cells, which was a more pronounced compared to its cytotoxic action on the parental DU145 cells. In a mouse xenograft prostate CSC-like model, intratumoral injection of GD55 markedly suppressed the growth rate of xenograft tumors and induced higher levels of cell death and necrosis within the tumor tissues. Our results demonstrate that GD55 infection exerts strong anticancer effects on prostate CSC-like cells in vitro and in vivo, and has a potential to be used in the clinical therapy of PCa.

Combination of oncolytic adenovirus and luteolin exerts synergistic antitumor effects in colorectal cancer cells and a mouse model.

In recent years, oncolytic viruses have attracted increasing interest due to their potent antitumor effects. Luteolin, a natural product, has additionally been observed to exhibit various pharmacological antitumor activities. Previously, a novel dual­targeting oncolytic adenovirus, complement decay­accelerating factor (CD55)­tumor necrosis factor ligand superfamily member 10 (TRAIL), was constructed, which exhibited significant growth inhibitory effects in various types of tumor cell. The present study investigated whether the combination of luteolin and CD55­TRAIL was able to exert a synergistic antitumor effect in colorectal carcinoma (CRC) cells. The cytotoxicity and tumor cell apoptosis mediated by combination treatment in CRC cells were detected via an MTT assay, Hoechst staining and western blotting, respectively. Tumor growth in vivo was examined in a CRC mouse xenograft model following various treatments. The results demonstrated that the addition of luteolin enhanced oncolytic adenovirus­mediated enhanced green fluorescent protein, early region 1A and TRAIL expression. The combination of CD55­TRAIL with luteolin synergistically inhibited tumor growth and promoted CRC cellular apoptosis in vitro and in vivo. Additionally, the combination of CD55­TRAIL with luteolin significantly decreased cytotoxicity in lung/bronchial normal epithelial cells, compared with single treatment. Therefore, the combination of CD55­TRAIL with luteolin may be a novel efficient therapeutic strategy for CRC in the future.

NaHS Protects against the Impairments Induced by Oxygen-Glucose Deprivation in Different Ages of Primary Hippocampal Neurons.

Brain ischemia leads to poor oxygen supply, and is one of the leading causes of brain damage and/or death. Neuroprotective agents are thus in great need for treatment purpose. Using both young and aged primary cultured hippocampal neurons as in vitro models, we investigated the effect of sodium hydrosulfide (NaHS), an exogenous donor of hydrogen sulfide, on oxygen-glucose deprivation (OGD) damaged neurons that mimick focal cerebral ischemia/reperfusion (I/R) induced brain injury. NaHS treatment (250 µM) protected both young and aged hippocampal neurons, as indicated by restoring number of primary dendrites by 43.9 and 68.7%, number of dendritic end tips by 59.8 and 101.1%, neurite length by 36.8 and 66.7%, and spine density by 38.0 and 58.5% in the OGD-damaged young and aged neurons, respectively. NaHS treatment inhibited growth-associated protein 43 downregulation, oxidative stress in both young and aged hippocampal neurons following OGD damage. Further studies revealed that NaHS treatment could restore ERK1/2 activation, which was inhibited by OGD-induced protein phosphatase 2 (PP2A) upregulation. Our results demonstrated that NaHS has potent protective effects against neuron injury induced by OGD in both young and aged hippocampal neurons.

Oncolytic viruses against cancer stem cells: A promising approach for gastrointestinal cancer.

Gastrointestinal cancer has been one of the five most commonly diagnosed and leading causes of cancer mortality over the past few decades. Great progress in traditional therapies has been made, which prolonged survival in patients with early cancer, yet tumor relapse and drug resistance still occurred, which is explained by the cancer stem cell (CSC) theory. Oncolytic virotherapy has attracted increasing interest in cancer because of its ability to infect and lyse CSCs. This paper reviews the basic knowledge, CSC markers and therapeutics of gastrointestinal cancer (liver, gastric, colon and pancreatic cancer), as well as research advances and possible molecular mechanisms of various oncolytic viruses against gastrointestinal CSCs. This paper also summarizes the existing obstacles to oncolytic virotherapy and proposes several alternative suggestions to overcome the therapeutic limitations.

Anti-tumor effects of Astragalus on hepatocellular carcinoma in vivo.

OBJECTIVE: The objective of the present study is to investigate the anti-proliferation activity of Astragalus on human hepatocellular carcinoma (HCC) cells and its mechanism. MATERIALS AND METHODS: Hepatic cancer H22 bearing mice were used to study the anti-hepatocarcinoma activity of Astragalus in vivo. The growth curve and inhibitory rate of tumor growth were measured. Cell apoptosis of each group was measured by flow cytometry (FCM). Protein expression of Bax and Bcl-2 were analyzed by immunohistochemistry (IHC). The Statistical Package for Social Sciences version 13.0 (SPSS Inc, Chicago, IL) was used for standard statistical analysis including one-way ANOVA and Student's t-test. A value of P<0.05 was considered to be statistically significant. RESULTS: Astragalus significantly inhibited the growth of H22 carcinoma, with an inhibitory rate of 17.28-52.36%. FCM and immunohistochemical assay show that the cell apoptosis rate and protein expression of Bax and Bax/Bcl-2 ratio of H22 transplanted tumor in Astragalus treated group were significantly higher than the control group (P<0.05). The protein expression of Bcl-2 was significantly lower than control (P<0.05). CONCLUSION: The results of the present study suggest that Astragalus has significant anti-tumor effect in vivo in inducing apoptosis of H22 tumor cells by promoting protein expression of Bax, decreasing protein expression of Bcl-2 gene, and markedly increasing the Bax/Bcl-2 ratio.