Prevention of acute graft-vs.-host disease by targeting glycolysis and mTOR pathways in activated T cells.

Graft-versus-host disease (GvHD) is a common life-threatening complication that can occur following allogeneic hematopoietic stem cell transplantation. This occurs if donor T cells recognize the host as foreign. During acute GvHD (aGVHD), activated T cells utilize glycolysis as the main source of energy generation. Therefore, inhibition of T cell glycolysis is a potential treatment strategy for aGVHD. In the present study, the effects of the combination of the glycolysis inhibitor 3-bromopyruvate (3-BrPA) and the mTOR inhibitor rapamycin (RAPA) on a mode of aGVHD were explored. In vitro mixed lymphocyte culture model was established by using splenocytes from C57BL/6 (H-2b) mice as responder and inactivated splenocytes from BALB/c (H-2d) mice as stimulator. In this model, 3-BrPA treatment (0-100 µmol/l) was found to suppress cell viability, increase cell apoptosis and reduce IFN-γ secretion, in a concentration-dependent manner. 3-BrPA treatment (0-100 µmol/l) was found to suppress cell viability, increase cell apoptosis and reduce IFN-γ secretion, in a concentration-dependent manner. In addition, combined treatment with 3-BrPA (0-100 µmol/l) alongside RAPA (20 µmol/l) exhibited synergistic effects on inhibiting cell viability and IFN-γ production, compared with those following either treatment alone. An aGVHD model was established by injection of bone marrow cells and spleen cells from the donor-C57BL/6(H-2b) mice to the receptor-BALB/c(H-2d) mice which were underwent total body irradiation first. In the aGVHD model, 3-BrPA (10 mg/kg/day), RAPA (2.5 and 5 mg/kg/day) and both in combination (5 and 2.5 mg/kg/day for 3-BrPA and RAPA, respectively) were all found to alleviate the damage caused by aGVHD, in addition to prolonging the survival time of mice with acute GvHD. In particular, the combined 3-BrPA and RAPA treatment resulted in the highest median survival time among all groups tested. In addition, the effects induced by combined 3-BrPA and RAPA treatment were found to be comparable to those in the 5 mg/kg/day RAPA group but superior to the 3-BrPA group with regards to the cumulative survival profile, GvHD score and lung histological score. The 3-BrPA and RAPA combination group also exhibited the lowest IFN-γ levels among all groups. Therefore, the combination of inhibiting both glycolysis and mTOR activity is a promising strategy for acute GvHD prevention.

A computed tomography-based radiomics signature for predicting expression of programmed death ligand 1 in head and neck squamous cell carcinoma.

OBJECTIVES: Accurate prediction of the expression of programmed death ligand 1 (PD-L1) in head and neck squamous cell carcinoma (HNSCC) before immunotherapy is crucial. This study was performed to construct and validate a contrast-enhanced computed tomography (CECT)-based radiomics signature to predict the expression of PD-L1 in HNSCC. METHODS: In total, 157 patients with confirmed HNSCC who underwent CECT scans and immunohistochemical examination of tumor PD-L1 expression were enrolled in this study. The patients were divided into a training set (n = 104; 62 PD-L1-positive and 42 PD-L1-negative) and an external validation set (n = 53; 34 PD-L1-positive and 19 PD-L1-negative). A radiomics signature was constructed from radiomics features extracted from the CECT images, and a radiomics score was calculated. Performance of the radiomics signature was assessed using receiver operating characteristics analysis. RESULTS: Nine features were finally selected to construct the radiomics signature. The performance of the radiomics signature to distinguish between a PD-L1-positive and PD-L1-negative status in both the training and validation sets was good, with an area under the receiver operating characteristics curve of 0.852 and 0.802 for the training and validation sets, respectively. CONCLUSIONS: A CECT-based radiomics signature was constructed to predict the expression of PD-L1 in HNSCC. This model showed favorable predictive efficacy and might be useful for identifying patients with HNSCC who can benefit from anti-PD-L1 immunotherapy. KEY POINTS: • Accurate prediction of the expression of PD-L1 in HNSCC before immunotherapy is crucial. • A CECT-based radiomics signature showed favorable predictive efficacy in estimation of the PD-L1 expression status in patients with HNSCC.

[Mechanism analysis of repeatedly steamed and sundried Rehmanniae Radix Praeparata in delaying brain aging in ovariectomized mice based on proteomics].

The present study explored the effect and mechanism of repeatedly steamed and sundried Rehmanniae Radix Praeparata(RRP) in delaying brain aging in ovariectomized mice. After ovariectomy, the mice were randomly divided into a model group, an estradiol valerate group(0.3 mg·kg~(-1)), and low-(1.0 g·kg~(-1)), medium-(2.0 g·kg~(-1)), and high-dose(4.0 g·kg~(-1)) RRP groups, and a sham operation group was also set up, with 15 mice in each group. One week after the operation, intragastric administration was carried out for 15 consecutive weeks. The step-down test and Morris water maze test were used to detect the behavioral changes of mice. HE staining and Nissl staining were used to observe the morphological changes of mouse brain tissues. Immunohistochemistry was used to detect the expression of Aß and ER_ß in mouse brain tissues. The serum estrogen levels and cholinesterase and cholinesterase transferase levels in brain tissues of mice were detected by assay kits. The extracted hippocampal protein was detected by the Nano-ESI-LC-MS system, identified by the Protein Discovery, and analyzed quantitatively and qualitatively by the SIEVE. The PANTHER Classification System was used for GO analysis and KEGG pathway enrichment analysis of the differential proteins. Compared with the sham operation group, the model group showed decreased learning and memory ability, shortened step-down latency(P<0.05), prolonged escape latency(P<0.05), reduced platform crossings and residence time in the target quadrant, scattered nerve cells in the hippocampus with enlarged intercellular space, increased expression of Aß-positive cells(P<0.05), declining expression of ER_ß-positive cells and estrogen level(P<0.05), and weakened cholinergic function(P<0.05). Compared with the model group, the RRP groups showed improved learning and memory ability, prolonged step-down latency(P<0.05), increased estrogen level(P<0.05), neatly arranged nerve cells in the hippocampus with complete morphology, declining Aß-positive cells, and elevated expression of ER_ß-positive cells. A total of 146 differential proteins were screened out by proteomics, and KEGG pathway enrichment yielded 75 signaling pathways. The number of proteins involved in the dopaminergic synapse signaling pathway was the largest, with 13 proteins involved. In summary, RRP can delay brain aging presumedly by increasing the level of estrogen, mediating the dopaminergic synapse signaling pathway, and improving cholinergic function.

[Relationship between Muscle Mass of Limbs and aGVHD in Patients with Allogeneic Hematopoietic Stem Cell Transplantation].

OBJECTIVE: To explore the correlation of limb muscle mass and acute graft-versus-host disease. METHODS: Clinical data from 144 patients treated by allo-HSCT in Guangzhou First People's Hospital were collected and analyzed retrospectively. The age, sex, diagnosis, donor age, sex of the donors, preparative regimen, ATG dose, HLA match, graft source, and number of infused stem cells of the patients were collected as baseline information. Meanwhile, bioelectrical impedance principle (BIA) was used to measure the limb muscle mass, body weight, body mass index (BMI), waist-to-hip ratio, upper arm muscle circumference, triceps skinfold thickness, and body fat rate of the patients before and after transplantation, so as to compare the changes of limb muscle mass and investigate its correlation with aGVHD. RESULTS: It was found that 61.11% of allo-HSCT patients showed muscle mass loss, and the proportion of male and female was 35.42% and 25.69%, respectively. There were reduction in the body weight, BMI, upper arm muscle circumference and muscle mass of limbs after transplantation as compared with those before transplantation (P<0.05). By comparing with the cumulative incidence of aGVHD between the patients in low muscle mass group and normal muscle mass group, it was found that the cumulative incidence of Ⅱ-Ⅳdegree aGVHD in patients with low muscle mass (30.38%) was higher than those with normal muscle mass (8.93%), which showed statistical difference (P<0.05). Univariate analysis showed that muscle mass, the sex of the donors, and preparative regimen were the influencing factors of aGVHD (P<0.05). Binary logistic regression showed that low muscle mass was the independent risk factor affecting aGVHD (P<0.05). CONCLUSION: Patients treated by allo-HSCT shows a decline in muscle mass after transplantation, and the incidence of aGVHD is high in patients with low muscle mass. Therefore, the assessment of muscle quality in early stage in patients with HSCT can facilitate earlier detection of aGVHD.

Early Detection of Magnaporthe oryzae-Infected Barley Leaves and Lesion Visualization Based on Hyperspectral Imaging.

Early detection of foliar diseases is vital to the management of plant disease, since these pathogens hinder crop productivity worldwide. This research applied hyperspectral imaging (HSI) technology to early detection of Magnaporthe oryzae-infected barley leaves at four consecutive infection periods. The averaged spectra were used to identify the infection periods of the samples. Additionally, principal component analysis (PCA), spectral unmixing analysis and spectral angle mapping (SAM) were adopted to locate the lesion sites. The results indicated that linear discriminant analysis (LDA) coupled with competitive adaptive reweighted sampling (CARS) achieved over 98% classification accuracy and successfully identified the infected samples 24 h after inoculation. Importantly, spectral unmixing analysis was able to reveal the lesion regions within 24 h after inoculation, and the resulting visualization of host-pathogen interactions was interpretable. Therefore, HSI combined with analysis by those methods would be a promising tool for both early infection period identification and lesion visualization, which would greatly improve plant disease management.

[Detection of Lead Chrome Green Illegally Added in Tea Based on Confocal Raman Spectroscopy].

In this paper, confocal Raman spectroscopy was applied to detect the contents of lead chrome green as a heavy-metal stain illegally added in tea. Firstly, Raman spectra of five different concentrations of lead chrome green in tea infusion were acquired based on specific concentration method. The qualitative analysis of sample added with lead chrome green was achieved with comparing the Raman spectra of sample and standard substance. Four main Raman characteristic wavenumbers, 1 341, 1 451, 1 527 and 1 593 cm(-1), were extracted for the qualitative identification of lead chrome green in tea. After spectral preprocessing of the raw Raman spectra, backward interval PLS (biPLS), competitive adaptive reweighted sampling (CARS) and successive projections algorithm (SPA) were combined to deeply mine the characteristic wavenumbers of lead chrome green in Raman spectra, and finally 14 characteristic wavenumbers were optimized. Partial least squares (PLS) and least square support vector machine (LS-SVM) were separately used to build the model based on the extracted 14 wavenumbers. As a result, these two models both had good robustness and high ability to predict and all the determination coefficient (R(2)) of calibration, validation and prediction were higher than 0.9, which proved the effectiveness of the extracted characteristic wavenumbers. Compared with the PLS model, the nonlinear model built by LS-SVM got a better result, R(2) of prediction was 0.964 and the root mean square error of prediction (RMSEP) was 0.535. This study indicated that it is feasible to detect the contents of lead chrome green illegally added in tea based on confocal Raman spectroscopy combined with specific sample treatment and chemometrics methods. This study helped the valid supervision of food safety problem on lead chrome green illegally added in tea.

Transcription factor SCL/TAL1 mediates the phosphorylation of MEK/ERK pathway in umbilical cord blood CD34⁺ stem cells during hematopoietic differentiation.

Transcription factor stem cell leukemia (SCL), also known as the T-cell acute lymphocytic leukemia 1 (TAL1), plays a key role in the regulation of hematopoiesis, but the molecular mechanisms are not well understood. The aim of the present study is to elucidate the effects of the epidermal growth factor receptor (EGFR) signal pathways underlying the biologic activity of SCL/TAL1 on normal hematopoietic development. Lentiviral vectors with up or down-regulation of SCL/TAL1 were transfected into umbilical cord blood CD34 stem cells. EGFR signaling pathways (including MEK/ERK and Akt/mTOR) and surface hematopoietic markers were analyzed in the process of hematopoietic differentiation. The data revealed that up or down-regulation of SCL/TAL1 gene was accompanied positively by the expressions of p-MEK and p-ERK1/2 protein, but the changes of Akt/mTOR were unobvious. MEK/ERK inhibitor U0126 and SCL/TAL1 down-regulation showed similar inhibitory effects on erythroid, myeloid, and megakaryoid differentiation. However, Akt/mTOR pathway altered insignificantly. MEK/ERK inhibitor U0126 could not affect the expression of SCL/TAL1 mRNA or protein. Taken together, these findings fully illustrated that SCL/TAL1 is located in the up-stream of MEK/ERK pathway and partially regulates hematopoiesis by modulating the phosphorylation level of the key proteins in MEK/ERK pathway.

[The optimization of method for lentiviral vector to transfect CD34+ hematopoietic stem cells from human cord].

OBJECTIVE: To identify the best transfect conditions for lentiviral vector to transfect CD34+ stem cells from human cord blood. METHODS: CD34+ hematopoietic stem cells from human cord blood were transduced with pTRIPdU3-RNAiTALh-EF1a-GFP plasmid expressing GFP by the second generation and third generation lentiviral vector system. The transfect conditions such as the concentration of the virus, polybrene, transfect volume and media, multiplicity of infection (MOI) values, incubating time and centrifugation in 12-well plate at 200 x g were tested to obtain optimal transfect conditions. The number of CFU were counted and the types of CFU were identified by light microscope after the transfected cells (non-infected stem cells served as control) were cultured for 14 days at a 37 degrees C, 5% CO2 incubator. RESULTS: The second-generation lentiviral vector plasmid had higher infect rate than the third-generation. The optimal transfect conditions were determined as: fresh sorting CD34+ cells, 10(7) TU virus concentration, Polybrene 2 microg/mL in opti-MEM medium, centrifuged at 200 x g for 1 h and then co-culture 8 h for cells and virus mixture in one well in flat-bottomed 12-well plate (repeated once). Both infected and non-infected CD34+ stem cells developed CFUs with similar numbers and types of colonies after being cultured for 14 days in the cytokine-containing 1:1 liquid medium/semi-solid medium. CONCLUSION: The identified optimal conditions can enable effective lentiviral vector transduction of CD34+ without interrupting the differentiation potential of the hematopoietic stem cells.

[Multidrug resistant gene MDR1 contributes to development of imatinib-resistance in Ph (+) acute lymphoblastic leukemia cell line SUP-BS15RI].

OBJECTIVE: To investigate the contribution of multidrug-resistant gene MDR1 to development of imatinib-resistance in Ph(+) acute lymphoblastic leukemia cell line SUP-B15/RI. METHODS: RT-PCR was used to examine MDR1 mRNA levels, cytotoxic effects of imatinib (IM), daunorubicin (DNR), vincristine (VCR), etoposide (VP-16) and the synergetic antiproliferation with P-gp inhibitor verapamil on sensitive SUP-B15 and SUP-B15/RI cell lines were detected by the MTT assay. The P-gp function was measured by flow cytometry. RESULTS: Increased expression of MDR1 gene in SUP-B15/RI than that of SUP-B15 cell line (P < 0.05) was observed when detected with RT-PCR. The IC50 values of SUP-B15/RI cell line inhibited by IM, DNR, VCR, VP-16 for 72 hours was higher than that of SUP-B15 (P < 0.05) and the resistant factor (RF) was (20.52 +/- 2.34), (10.33 +/- 1.88), (9.78 +/- 1.27), (3.84 +/- 0.69) respectively. The IC50 values of IM, DNR, VCR, VP-16 combined with P-gp inhibitor verapamil were decreased in SUP-B15/RI cells (P < 0.05), reversal of drug resistance was (1.44 +/- 0.43), (3.20 +/- 0.17), (1.44 +/- 0.12), (1.33 +/- 0.14) respectively. The activity of P-gp in SUP-B15/RI measured by flow cytometry was higher than that of P-gp in SUP-B15/RI cell line. CONCLUSION: The overexpression of MDR1 mRNA and higher activity of P-gp is partially responsible for acquiring of imatinib resistance in SUP-B15/RI cell line. P-gp inhibitor verapamail can partially restored the sensitivity of the SUP-B15/RI cell line to anticancer agents.

[Anti-leukemia effect of oridonin on Ph(+) acute lymphoblastic leukemia cell SUP-B15].

OBJECTIVE: To investigate the anti-leukemia effect of oridonin on Ph(+) acute lymphoblastic leukemia (ALL) cell line SUP-B15. METHODS: Human Ph(+) ALL cell line was cultured in vitro. The 50% inhibition concentration (IC(50)) of oridonin against SUP-B15 cell line was examined using modified MTT assay. The cellular morphologic changes were observed using a light microscope. The percent of apoptosis of SUP-B15 cell line after drug treatment was evaluated by flow cytometric analysis. The active levels of ABL kinase and its downstream Akt/mTOR, Raf/MEK/ERK, STAT5 signaling pathways and the expression levels of Bcl-2 and BAX were examined by Western blot. RESULTS: Oridonin inhibited the growth of SUP-B15 cell line in both time- and dose-dependent manner with the IC(50) of oridonin as (7.08 ± 1.21) µmol/L after 72 h treatment. The cellular membrane of SUP-B15 cell line treated with oridonin became unsharp, some of them disintegrated. Oridonin induced apoptosis in SUP-B15 cell line with the apoptosis rates following 0, 5, 10 µmol/L oridonin treatment for 24 h were (6.67 ± 0.83)%, (18.30 ± 1.79)% and (37.63 ± 7.12)%, respectively. Oridonin inhibited activation of ABL kinase and its downstream Akt/mTOR, Raf/MEK/ERK and STAT5 signaling pathways, which were constitutively activated in SUP-B15 cell line, down-regulated the level of anti- apoptotic protein Bcl-2 and up-regulated the expression of pro-apoptotic protein Bax. CONCLUSION: Oridonin exerted anti-leukemia effect in Ph(+)ALL cell line SUP-B15 by inhibiting the activation of ABL kinase and its downstream Akt/mTOR, Raf/MEK/ERK and STAT5 signaling pathways, down-regulating the expression of Bcl-2 and up-regulating the expression of BAX.

[The effect of knockdown of transcription factor SCL/TAL-1 gene on the erythroid differentiation in EPO-induced K562 cell line].

OBJECTIVE: To investigate the role of transcript factor SCL/TAL-1 gene in the erythroid differentiation through the knockdown of SCL/TAL-1 mRNA by RNA interference. METHODS: The plasmid of pTRIP-dU3-RNAiTALh-EF1a-GFP with SCL/TAL1 shRNA was transfected into EPO-induced K562 cell line with erythroid differentiation via lentiviral vector system and the expression of SCL/TAL-1 mRNA decreased. The plasmid pTRIP-dU3- RNAiluc-EF1-GFP expressing EGFP gene was as control. The mRNA levels of SCL/TAL-1 and erythroid related RhD, GPA, CD47 in the cell lines were detected by RT-PCR, and erythroid antigen CD71, CD235a were examined by flow cytometry. RESULTS: (1) After 48 h of transfect, more than 95% of K562 cells were GFP positive, indicating the infection rate of the plasmids in the K562 cells more than 95%. (2) The results of RT-PCR showed SCL/TAL-1 mRNA expression in the K562 cell line of knockdown of SCL/TAL-1 was significantly lower than that in the control (P < 0.05). The mRNA levels of CD47 and RhD were also significantly lower, however, GPA decreased slightly in comparison with the control. (3) The expressions of CD71 and CD235a markedly reduced in the K562 cell line of knockdown of SCL/TAL-1 with positive rates as 10.4% and 76.5%, while the positive rates in the control as 94.3% and 83.6%. CONCLUSION: Our findings suggested that transcription factor SCL/TAL-1 might play an positive role in erythroid differentiation.

[Anti-tumor effect of tanshinone II A, tetrandrine, honokiol, curcumin, oridonin and paeonol on leukemia cell lines].

OBJECTIVE: To study the anti-tumor effect of tanshinon II A, tetrandrine, honokiol, curcumin, oridonin and paeonol on leukemia cell lines SUP-B15, K562, CEM, HL-60 and NB4. METHODS: To study the anti-tumor effect of tanshinone II A, tetrandrine, honokiol, curcumin, The leukemia cell lines were exposed to the six Chinese herbal components for 96 hours. The proliferative inhibitory effects were detected with MTT and described by IC50 value. RESULTS: Tanshinone II A inhibited the proliferations of SUP-B15, K562, CEM, HL-60 and NB4 cell lines, with HL-60 showing the least impact. Tetrandrine, honokiol, curcumin and oridonin inhibited the proliferations of SUP-B15, K562, CEM, HL-60 and NB4 cell lines and there was no significant difference between the cell lines. Paeonol did not have significant inhibitory effect on leukemia cell lines. CONCLUSION: Tetrandrine, honokiol, curcumin and oridonin inhibit the proliferation of five cell lines SUP-B15, K562, CEM, HL-60, NB4, and the effects are similar, which means that their anticancer effects are quite broad. Tanshinone II A has better anti-leukemia effects on SUP-B15, K562, CEM, NB4 than on HL-60. The effect of paeonol against leukemia cell lines is poor.

[Effects of bortezomib combined with daunorubicin on proliferation and apoptosis in primary adult acute leukemia].

OBJECTIVE: To assess effects of proteasome inhibitor Bortezomib (Bor) in combination with Daunorubicin (DNR) on proliferation, apoptosis and the expression of Bcl-2 mRNA in primary leukemia cells in vitro. METHODS: Primary leukemia cells were isolated from bone marrow of adult acute leukemia patients using Ficoll liquid, then the primary leukemia cells were treated with different concentration of these two drugs (Bor 5, 10, 20, 50 nmol/L, DNR 50, 100, 200, 500 nmol/L, and Bor 5, 10 nmol/L combined with DNR 50, 100, 200, 500 nmol/L respectively ). Cells proliferation, IC50 and CDI were analyzed by MTT assay, cellular apoptosis was observed by flow cytometry, Bcl-2 mRNA was analyzed by RT-PCR. RESULTS: Growth inhibition ratio of all the types of acute leukemia cells were increased with the treatment of DNR and Bor in dose-dependent manner. Combined with Bor (5, 10 nmol/L),the IC50 of DNR decreased from (102 +/- 27) nmol/L to (73 +/- 26), (55 +/- 22) nmol/L respectively. DNR 200 nmol/L combined with Bor 10 nmol/L showed a better synergism (CDI = 0. 17). Compared with control group and single drug (DNR or Bor) group, there were obvious increase of apoptosis ratio and obvious decrease of Bcl-2 in the group of DNR 100 nmol/L combined with Bor 20 nmol/L after 24 h or 48 h cultivation (P < 0.05). CONCLUSION: Bor combined with DNR shows synergetic effect in promoting the apoptosis of adult acute leukemia primary cells as well as inhibitory effect on the proliferation of leukemia cells.

[The anti-leukemic effects of imatinib, daunorubicin and bortezomib on two leukemia cell lines with Ph(+)].

OBJECTIVE: To study the proliferative inhibition effects of imatinib, daunorubicin and bortezomib on two leukemia cell lines with Ph(+), chronic myelogenous leukemia cell line K562 expressing P210 protein and acute lymphoblastic leukemia cell line SUP-B15 expressing P190 protein. METHODS: (1) The cells of the two cell lines treated with imatinib, daunorubicin and bortezomib for 72 hours were analyzed by MTT assay for proliferation. The proliferative activity was displayed by growth curve and IC50 value. (2) The bcr-abl transcriptant in the cells treated with imatinib (final concentration at 0, 0.35, 1 micromol/L) for 48 hours was detected by reverse transcription polymerase chain reaction (RT-PCR). RESULTS: (1) The IC50 values of K562 and SUP-B15 cell lines treated with imatinib, daunorubicin and bortezomib for 72 hours were respectively (0.286 +/- 0.060) micromol/L, (0.303 +/- 0.009) micromol/L, (22.127 +/- 3.592) nmol/L and (1.387 +/- 0.180) micromol/L, (0.117 +/- 0.017) micromol/L, (12.350 +/- 0.740) nmol/L. (2) There was no change of bcr-abl expression level in both cell lines after the treatment of imatinib. CONCLUSION: Imatinib, daunorubicin and bortezomib showed anti-cancer effects on Ph(+) leukemia cells in vitro. K562 cells were more sensitive to imatinib than the other two drugs, whereas SUP-B15 cells are more sensitive to daunorubicin and bortezomib. The short time intervention of imatinib has no effect on the expression of bcr-abl in Ph (+) leukemia cell lines.

[Correlation between postmortem intervals and the changes of electrical conductivity in vitreous humor in rabbits after death].

OBJECTIVE: To investigate the correlation between postmortem interval (PMI) and the changes of electrical conductivity in vitreous humor in rabbits after death. METHODS: The changes of electrical conductivity in vitreous humor in rabbits were measured using the conductivity meter under 30 degrees C during 0-48 hours and 20 degrees C during 0-120 hours after death. RESULTS: Electrical conductivity in vitreous humor in rabbits increased gradually under 30 degrees C and 20 degrees C from 0 to 48 hours and from 0-120 hours after death. The formulae of the relationship between PMI and conductivity under 30 degrees C and 20 degrees C were obtained by statistical analysis and the correlation coefficients were 0.970 and 0.983 (both P < 0.01), respectively. CONCLUSION: The increase of electrical conductivity in vitreous humor in rabbits after death may be used as the relatively objective parameter for PMI estimation.