Limited value of platelet-related markers in diagnosing periprosthetic joint infection.

OBJECTIVE: To evaluate the diagnostic values of serum platelet count (PC), mean platelet volume ratio (MPV), platelet count to mean platelet volume ratio (PVR), platelet to lymphocyte ratio (PLR), platelet to neutrophil ratio (PNR), PC/Albumin-globulin ratio (PC/AGR), and PC/C-reactive protein (PC/ CRP) in the diagnosis of periprosthetic joint infection (PJI). METHODS: The medical records were retrospectively analyzed of the 158 patients who had undergone hip or knee revisions from January 2018 to May 2022. Of them, 79 cases were diagnosed with PJI and 79 with aseptic loosening (AL). PJI was defined using the Musculoskeletal Infection Society criteria. The plasma levels of CRP, the erythrocyte sedimentation rate (ESR), PC, MPV, PVR, PLR, PNR, PC/AGR, and PC/CRP in the 2 groups were recorded and analyzed. In addition, tests were performed according to different joint types. The receiver operating characteristic curve was used to calculate the sensitivity and specificity of each indicator. The diagnostic value for each indicator was calculated according to the area under the curve (AUC). RESULTS: The PC, PVR, PLR and PC/AGR levels in the PJI group were significantly higher than those in the AL group, while PC/CRP levels were significantly lower (P < 0.001). The AUC for PC/CRP, and PC/AGR was 0.804 and 0.802, respectively, which were slightly lower than that of CRP (0.826) and ESR (0.846). ROC analysis for PC/CRP, and PC/AGR revealed a cut-off value of 37.80 and 160.63, respectively, which provided a sensitivity of 73.42% and 84.81% and a specificity of 75.95% and 65.82% for PJI. The area under the curve of PLR and PC was 0.738 and 0.702. The area under the curve values for PVR, PNR, and MPV were 0.672, 0.553, and 0.544, respectively. CONCLUSIONS: The results of this study suggest that PC, PLR, PC/CRP, and PC/AGR values do not offer significant advantages over ESR or CRP values when employed for the diagnosis of PJI. PVR, PNR, and MPV were not reliable in the diagnosis of PJI.

Complete androgen insensitivity syndrome: a case report and literature review.

Complete androgen insensitivity syndrome (CAIS) is a rare disease that can be easily misdiagnosed. Before puberty, this condition is easily misdiagnosed as an inguinal hernia. This case report describes a 31-year-old phenotypically female patient with CAIS who was misdiagnosed twice previously with an inguinal hernia. Her karyotype analysis showed that she was 46, XY. She underwent a bilateral gonadectomy and long-term hormone replacement therapy. A Leydig cell tumour of the right testis was diagnosed postoperatively. This report also reviews the current understanding of the diagnosis and treatment of CAIS.

Albumin to Globulin ratio, Neutrophil to Lymphocyte ratio, and Globulin levels do not outperform ESR or CRP when diagnosing periprosthetic joint infection.

OBJECTIVE: To evaluate the relative performance of clinical readouts including serum C-reactive protein (CRP) levels, the erythrocyte sedimentation rate (ESR), globulin (GLB) levels, the albumin to GLB ratio (A/G), and the neutrophil to lymphocyte ratio (NLR) when diagnosing periprosthetic joint infection (PJI). METHODS: Clinical data was collected from 115 individuals diagnosed in our department between January 2017 and December 2020 with either chronic PJI (29 female, 24 male; median age 71.00 years [range, 41-94 years]) or aseptic loosening (30 female, 32 male; median age 68.50 years [range, 34-85 years]). Patient demographic data were compared, and the relative sensitivity and specificity of preoperative GLB, ESR, CRP, NLR, and A/G values as predictors of PJI diagnosis were assessed. RESULTS: Median globulin levels in the PJI and aseptic groups were 31.700 g/L (interquartile range [IQR], 28.400-35.300) and 26.600 g/L (IQR, 24.375-30.550), respectively (p < 0.001). The median A/G values in the PJI and aseptic groups were 1.150 (IQR, 0.960-1.255) and 1.510 (IQR, 1.265-1.670), respectively (p < 0.001). The median NLR values in the PJI and aseptic groups were 2.510 (IQR, 1.900-3.335) and 1.850 (IQR, 1.425 to 2.362), respectively (p < 0.001). The median ESR values in the PJI and aseptic groups were 53.000 mm/h (IQR, 35.000-76.500) and 16.000 mm/h (IQR, 7.000-33.000), respectively (p < 0.001). Median CRP levels in the PJI and aseptic groups were 24.890 mg/L (IQR, 10.595-54.095) and 2.245 mg/L (IQR, 0.865-8.6075), respectively (p < 0.001). Area under the receiver operating characteristic (ROC) curve (AUC) values for CRP, ESR, GLB, A/G, and NLR were 0.841 (95% confidence interval, 0.761-0.903), 0.850 (0.771-0.910), 0.747 (0.658-0.824), 0.779 (0.692-0.851), and 0.708 (0.616-0.789), respectively. When GLB > 26.6 g/L, A/G < 1.32, and NLR > 2.1 were utilized as threshold values to diagnose PJI, GLB and A/G were found to exhibit superior sensitivity (90.57%, 81.13%) to that observed for CRP (71.70%) and ESR (79.25%), but the specificity of these two metrics (GLB: 51.61%, A/G: 72.58%) was significantly reduced relative to that for CRP (87.10%) or ESR (75.81%). ROC analyses further revealed that NLR did not exhibit significant advantages in sensitivity (73.58%) or specificity (70.97%) relative to CRP or ESR. CONCLUSION: Globulin levels, NLR values, and A/G values do not outperform ESR or CRP levels when used to diagnose PJI.

[Imaging characteristic of Stafne bone cavity：a retrospective study based on cone-beam CT].

PURPOSE: To guide clinical decision-making more efficiently via collecting and analyzing the imaging data of patients with Stafne bone cavity(SBC). METHODS: Six patients with SBC were retrospectively reviewed in Stomatological Hospital of Shandong University. By assessing cone-beam CT (CBCT) data, age, sex, complaint, cavity location, diameter at three dimension, maximal cross-sectional area of multi-planar reconstruction planes, content gray scale, morphological classification and its relationship with mandibular canal were recorded respectively. RESULTS: A total of 6 cases were inadvertently found on CBCT, with no symptoms. The locations of SBC were between mandibular molar region and mandibular angle, inferior border of mandible and mandibular canal, mostly at lingual side. Three were on the left and three were on the right. The bone cavity was elliptic and its long axis was consistent with the long axis of the mandible, with an average long axis diameter of (16.43±4.54) mm, horizontal axis diameter of (6.91±1.48) mm, vertical axis diameter of (10.24±2.10) mm. According to the multi-planar reconstruction planes readings, the maximal cross-sectional area of the bone cavity was (91.93±25.52) mm2, the maximal coronal area was (57.26±23.23) mm2, and the maximal sagittal area was (127.80±51.22) mm2. In view of the classification in the relationship between SBC marginal line and buccal cortical bone, there were 2 cases of type I cavity, 3 cases of type II cavity and 1 case of type III cavity. The connection between the bone cavity and the surrounding anatomical structure was classified into 3 conditions: covering penetration, adjacency and separation on the basis of the relative position between the cavity boundary with the mandibular inferior margin and the mandibular canal in sagittal plane. In addition, the content type could be primarily identified depending on estimation of corrected grey scale in the center of bone cavity. CONCLUSIONS: CBCT can make an intuitive and clear diagnosis of Stafne bone cavity, which brings great significance into the early clinical decision-making, thus not only avoiding unnecessary surgery, reducing the waste of additional medical resources, but also decreasing the physical and mental trauma of patients.

[Study on Behavioral Factors Affecting the Risk of New HBV Infection among Diabetic Patients].

OBJECTIVE: To analyze the behavioral factors influencing of new hepatitis B virus (HBV) infection in diabetic patients, so as to provide evidence for reducing the risk of new HBV infection in diabetic patients. METHODS: A nested case-control study was conducted to follow up and observe 4 586 diabetic patients. The 114 diabetic patients who newly developed HBV infection during the follow-up period were selected as the case group, and 228 diabetic patients who did not develop HBV infection in the same period were selected as the control group from the cohort population at a matching ratio of 1∶2 according to the age ±2 years. Questionnaire surveys and laboratory examinations were conducted in the cohort. The contents of the questionnaire included family history of hepatitis B, history of trauma, history of receiving/donating blood, individual-related behavioral characteristics, diabetes severity, and behavior related to diabetes treatment and management. In addition, the blood samples of the cohort were tested for hepatitis B surface antigen (HBsAg) by enzyme-linked immunosorbent assay (ELISA). The conditional logistic regression model was used to analyze the related behavioral factors affecting new HBV infection in diabetic patients. RESULTS: The median ages of the HBV group and the control group were 64 years old and 66 years old, respectively. There was no statistically significant difference in the composition of sex, age, ethnicity, occupation and amount of formal education between the two groups ( P>0.05). Multivariate analysis showed that diabetic patients with a family history of hepatitis B ( OR=13.052, 95% CI: 3.799 to 44.847) had a higher risk of new HBV infection, while diabetic patients who used blood collection/injection devices in a standardized way ( OR=0.189, 95% CI: 0.082 to 0.436), safety locking blood glucose needles ( OR=0.142, 95% CI: 0.073 to 0.276) and venous blood collection needles ( OR=0.019, 95% CI: 0.001 to 0.262) and self-testing of blood sugar at home ( OR=0.466, 95% CI: 0.222 to 0.980) had a lower risk of new HBV infection. CONCLUSION: Family history of hepatitis B is an independent factor that increases the risk for new HBV infection in diabetic patients. During the process of long-term blood glucose management of diabetic patients, standardized use of blood collection/injection devices, use of safer types of blood sampling lancet, and self-testing of blood glucose help can reduce the risk of HBV infection.

Exciting Performance of Plasma Fibrinogen in Periprosthetic Joint Infection Diagnosis.

OBJECTIVE: To test the significance of serum C-reactive protein (CRP), the erythrocyte sedimentation rate (ESR), the platelet count/mean platelet volume ratio (PC/MPV), plasma fibrinogen, and D-Dimer in periprosthetic joint infection (PJI) diagnosis. METHODS: We retrospectively analyzed the clinical data of 149 patients diagnosed from July 2016 to December 2019 with primary osteoarthritis (OA group, average age 63.18 years [range, 53-82 years] 18 males, 46 females), PJI (PJI group, average age 63.74 years [range, 52-81 years], 16 males, 31 females), and aseptic loosening (aseptic group, average age 63.18 years [range, 53-80 years], 12 male, 26 female) in our department. Demographic data and the sensitivity and specificity of preoperative CRP, ESR, PC/MPV, fibrinogen, and D-Dimer in PJI diagnosis were compared. RESULTS: There were no significant differences when the demographic data of the three groups were compared. The expression level of CRP (50.67 ± 58.98 mg/L), ESR (50.55 ± 25.81 mm/h), PC/MPV (35.79 ± 18.00), and fibrinogen (4.85 ± 1.33 µg/mL) in the PJI group were higher than in the OA group (CRP: 4.09 ± 9.68 mg/L; ESR:13.44 ± 9.32 mm/1 h; PC/MPV: 24.97 ± 7.58; fibrinogen: 3.09 ± 0.55 µg/mL) and the aseptic group (CRP: 7.01 ± 11.83 mg/L; ESR: 22.47 ± 17.53 mm/1 h; PC/MPV: 25.18 ± 11.48; fibrinogen: 3.39 ± 0.80 µg/mL), respectively. The expression level of plasma D-dimer (1.60 ± 1.29 mg/L) in the PJI group was higher than in the OA group (0.49 ± 0.42 mg/L) but similar to that in the aseptic group (1.21 ± 1.35 mg/L). Receiver operating characteristic (ROC) curve analysis demonstrated that the areas under the ROC curve (AUC) for CRP, ESR, PC/MPV, fibrinogen, and D-dimer were 0.892 (95% confidence interval, 0.829-0.954), 0.888 (0.829-0.947), 0.686 (0.589-0.784), 0.873 (0.803-0.943), and 0.835 (0.772-0.899), respectively. When PC/MPV > 31.70, fibrinogen >4.01 µg/mL, and D-dimer >1.17 mg/L were set as the threshold values for the diagnosis of PJI, the sensitivity of PC/MPV in PJI diagnosis was lower than that of ESR and plasma fibrinogen. In contrast, there was no significant difference when comparing the specificity of CRP, ESR, PC/MPV, fibrinogen, and D-dimer in PJI diagnosis. CONCLUSION: Plasma fibrinogen is a good new auxiliary diagnostic marker for PJI.

[Associations between Takeaway Food Nutrients and Nutritional Literacy of Takeaway Platform Practitioners in Chengdu].

Objective To investigate the nutritional literacy levels of the takeaway platform practitioners in Chengdu,the takeaway food nutrients,and the correlation between them.Methods We employed a multi-stage random sampling method to investigate the nutritional literacy levels of 100 takeaway platform restaurants in the main urban area of Chengdu and examined the nutritional components of hot set meals in each restaurant.A questionnaire survey was conducted on the nutritional literacy levels of chefs and food matching staff.The correlations of nutrient energy supply rationality with nutritional literacy level and set meal price were then analyzed.Results The total pass rate of nutrition knowledge of chefs/food matching staff was 61.0%.Only 2.0% of the set meals had reasonable total energy supply.The set meals with reasonable energy supply of available carbohydrate,protein,and fat accounted for 3.0%,62.0%,and 21.0%,and those with over energy supply accounted for 97.0%,26.0%,and 73.0%,respectively.The rest set meals provided insufficient energy.There was a positive correlation between the nutritional literacy level and the rationality of protein energy supply(r=0.414,P=0.003).Conclusions The nutritional literacy levels of chefs/food matching staff of takeaway food restaurants in Chengdu are moderate.The hot set meals on the takeaway platform have the problem of excess energy supply.The nutrition knowledge of chefs/food matching staff cannot effectively satisfy rational nutrition matching.The nutritional literacy levels of chefs/food matching staff showed no significant correlation with the rationality of nutrient energy supply.

Identification of aberrantly methylated differentially expressed genes targeted by differentially expressed miRNA in osteosarcoma.

BACKGROUND: Osteosarcoma (OS) is the most common primary bone tumors diagnosed in children and adolescents. Recent studies have shown a prognostic role of DNA methylation in various cancers, including OS. The aim of this study was to identify the aberrantly methylated genes that are prognostically relevant in OS. METHODS: The differentially expressed mRNAs, miRNAs and methylated genes (DEGs, DEMs and DMGs respectively) were screened from various GEO databases, and the potential target genes of the DEMs were predicted by the RNA22 program. The protein-protein interaction (PPI) networks were constructed using the STRING database and visualized by Cytoscape software. The functional enrichment and survival analyses of the screened genes was performed using the R software. RESULTS: Forty-seven downregulated hypermethylated genes and three upregulated hypomethylated genes were identified that were enriched in cell activation, migration and proliferation functions, and were involved in cancer-related pathways like JAK-STAT and PI3K-AKT. Eight downregulated hypermethylated tumor suppressor genes (TSGs) were identified among the screened genes based on the TSGene database. These hub genes are likely involved in OS genesis, progression and metastasis, and are potential prognostic biomarkers and therapeutic targets. CONCLUSIONS: TSGs including PYCARD, STAT5A, CXCL12 and CXCL14 were aberrantly methylated in OS, and are potential prognostic biomarkers and therapeutic targets. Our findings provide new insights into the role of methylation in OS progression.

NVP-BEZ235 synergizes cisplatin sensitivity in osteosarcoma.

Osteosarcoma(OS) remains a major health concern in childhood and adolescence, although cisplatin is one of the gold standard chemotherapeutic drugs in the treatment of OS, chemoresistant to cisplatin is common. Phosphoinositide 3-kinase (PI3K)-Akt-mammalian target of rapamycin inhibitor (mTOR) pathway and autophagy regulates chemosensitivity incancer cells. In this study, we hypothesized that NVP-BEZ235, a dual inhibitor of PI3K/mTOR, could synergize cisplatin sensitivity in OS. In vitro, NVP-BEZ235 plus cisplatinexerted a synergistic effect on cell proliferation inhibition and apoptosis induction. Cisplatin could activate PI3K-Akt-mTOR pathway activity in early times, whereas, NVP-BEZ235 could inhibit PI3K-Akt -mTOR pathway activity all the times alone or combined with cisplatin. What's more, NVP-BEZ235 could switch function of autophagy induced by cisplatin to synergize cisplatin sensitivity. In vivo, pronounced decrease in tumor cell proliferation and increase in apoptosisin combination-treated mouse xenograft models compared with cisplatin or NVP-BEZ235 treated models. All these results suggest NVP-BEZ235 could synergize cisplatin sensitivity in OS, combination of NVP-BEZ235 with cisplatin could represent a novel therapeutic strategy for treatment of OS.

Finite element analysis of the stability of combined plate internal fixation in posterior wall fractures of acetabulum.

OBJECTIVE: This study aims to explore the mechanical stability of combined plate internal fixation in posterior wall fractures of the acetabulum. METHODS: The fracture and internal fixation models were established in this study and they were divided into four kinds of internal fixation models, finite element analysis was performed. The four groups were 2 mini-plates and 1 reconstruction plate fixation (A), Reconstruction plate internal fixation group (B), 2 screws internal fixation group (C) and mini-plates internal fixation group (D). The displacement of each node was measured and evaluated. RESULTS: There was no distortion in the geometric shape of the finite element model. The results of stress showed that it was less in the anterior pelvic ring and distributed uniform in labrum acetabulare; the stress was bigger in the upper and middle of sacroiliac joint and sciatic notch in sitting position. CONCLUSIONS: Combined plate internal fixation for posterior wall fractures of acetabular were stable and reliable, it is better than the other three methods.

Clinical effectiveness analysis of dextran 40 plus dexamethasone on the prevention of fat embolism syndrome.

This study aims to investigate the clinical efficacy of Dextran 40 plus dexamethasone on the prevention of fat embolism syndrome (FES) in high-risk patients with long bone shaft fractures. According to the different preventive medication, a total of 1837 cases of long bone shaft fracture patients with injury severity score (ISS) > 16 were divided into four groups: dextran plus dexamethasone group, dextran group, dexamethasone group and control group. The morbidity and mortality of FES in each group were analyzed with pairwise comparison analysis. There were totally 17 cases of FES and 1 case died. The morbidity of FES was 0.33% in dextran plus dexamethasone group and significantly lowers than that of other groups (P < 0.05). There was no significant difference among other groups (P > 0.05). Conclusion from our data is dextran 40 plus dexamethasone can effectively prevent long bone shaft fractures occurring in high-risk patients with FES.

Allosteric modulation of related ligand-gated ion channels synergistically induces long-term potentiation in the hippocampus and enhances cognition.

α5 Subunit-containing GABA(A) receptors (GABA(A)Rs) and α7 neuronal nicotinic-acetylcholine receptors (nAChRs) are members of the Cys-loop family of ligand-gated ion channels (LGICs) that mediate cognitive and attentional processes in the hippocampus. α5 GABA(A)Rs alter network activity by tonic inhibition of CA1/CA3 pyramidal cells of the hippocampus. Postsynaptic α7 nAChRs in the hippocampus regulate inhibitory GABAergic interneuron activity required for synchronization of pyramidal neurons in the CA1, whereas presynaptic α7 nAChRs regulate glutamate release. Can simultaneous allosteric modulation of these LGICs produce synergistic effects on cognition? We show that combined transient application of two allosteric modulators that individually 1) inhibit α5 GABA(A)Rs and 2) enhance α7 nAChRs causes long-term potentiation (LTP) of mossy fiber stimulation-induced excitatory postsynaptic currents (EPSC) from CA1 pyramidal neurons of rat hippocampal slices. The LTP effect evoked by two compounds is replicated by 3-(2,5-difluorophenyl)-6-(N-ethylindol-5-yl)-1,2,4-triazolo[4,3-b]pyridazine (522-054), a compound we designed to simultaneously inhibit α5 GABA(A)Rs and enhance α7 nAChRs. Selective antagonists for either receptor block sustained EPSC potentiation produced by 522-054. In vivo, 522-054 enhances performance in the radial arm maze and facilitates attentional states in the five-choice serial reaction time trial with similar receptor antagonist sensitivity. These observations may translate into therapeutic utility of dual action compounds in diseases of hippocampal-based cognitive impairment.

Limiting activity at beta1-subunit-containing GABAA receptor subtypes reduces ataxia.

GABA(A) receptor (R) positive allosteric modulators that selectively modulate GABA(A)Rs containing beta(2)- and/or beta(3)- over beta(1)-subunits have been reported across diverse chemotypes. Examples include loreclezole, mefenamic acid, tracazolate, and etifoxine. In general,"beta(2/3)-selective" GABA(A)R positive allosteric modulators are nonbenzodiazepines (nonBZs), do not show alpha-subunit isoform selectivity, yet have anxiolytic efficacy with reduced ataxic/sedative effects in animal models and humans. Here, we report on an enantiomeric pair of nonBZ GABA(A)R positive allosteric modulators that demonstrate differential beta-subunit isoform selectivity. We have tested this enantiomeric pair along with a series of other beta(2/3)-subunit selective, alpha-subunit isoform-selective, BZ and nonBZ GABA(A) positive allosteric modulators using electrophysiological, pharmacokinetic, and behavioral assays to test the hypothesis that ataxia may be correlated with the extent of modulation at beta(1)-subunit-containing GABA(A)Rs. Our findings provide an alternative strategy for designing anxioselective allosteric modulators of the GABA(A)R with BZ-like anxiolytic efficacy by reducing or eliminating activity at beta(1)-subunit-containing GABA(A)Rs.

Enaminone amides as novel orally active GABAA receptor modulators.

A series of enaminone esters and amides have been developed as potent allosteric modulators of gamma-aminobutyric acidA (GABAA) receptors. The compounds bind to a novel modulatory site that is independent of the benzodiazepine (BZ), isosteric GABA, and neuroactive steroid binding sites. Structure-activity relationship (SAR) studies resulted in the synthesis of the c-Bu amide 16h with an in vitro potency of 7 nM based on inhibition of [35S]TBPS binding. The activity of the enaminones as positive allosteric modulators was confirmed with electrophysiological measurements in oocytes expressing alpha1beta2gamma2L GABAA receptors. The i-Pr, s-Bu, c-Pr, and c-Bu amides (16e-h) were orally active in mice with profound central nervous system depressant effects. The i-Pr amide 16e was an orally active anxiolytic in the mouse light-dark paradigm.

DiPOA ([8-(3,3-diphenyl-propyl)-4-oxo-1-phenyl-1,3,8-triazaspiro[4.5]dec-3-yl]-acetic acid), a novel, systemically available, and peripherally restricted mu opioid agonist with antihyperalgesic activity: I. In vitro pharmacological characterization and pharmacokinetic properties.

Mu opioid receptors are present throughout the central and peripheral nervous systems. Peripheral inflammation causes an increase in mu receptor levels on peripheral terminals of primary afferent neurons. Recent studies indicate that activation of peripheral mu receptors produces antihyperalgesic effects in animals and humans. Here, we describe the in vitro pharmacological and in vivo pharmacokinetic properties of a novel, highly potent, and peripherally restricted mu opioid agonist, [8-(3,3-diphenyl-propyl)-4-oxo-1-phenyl-1,3,8-triaza-spiro[4.5]dec-3-yl]-acetic acid (DiPOA). In a radioligand binding assay, DiPOA inhibited [(3)H]-diprenorphine binding to recombinant human mu receptors with a K(i) value of approximately 0.8 nM. The rank order of affinity for DiPOA binding to recombinant human opioid receptors was mu > kappa approximately ORL-1 >> delta. DiPOA showed potent agonist effects in a human mu receptor guanosine 5'-O-(3-[(35)S]thio)triphosphate functional assay, with an EC(50) value of approximately 33 nM and efficacy of approximately 85% [normalized to the mu agonist, [d-Ala2,MePhe4,Gly(ol)5]enkephalin]. Low potency agonist activity was also seen at ORL-1 and kappa receptors. DiPOA bound competitively to the opioid binding site of human mu receptors as demonstrated by a parallel rightward shift in its concentration-response curve in the presence of increasing concentrations of naltrexone. High and sustained (> or =5 h) plasma levels for DiPOA were achieved following intraperitoneal administration at 3 and 10 mg/kg; central nervous system penetration, however, was < or =4% of the plasma concentration, even at levels exceeding 1500 ng/ml. As such, DiPOA represents a systemically available, peripherally restricted small molecule mu opioid agonist that will aid in understanding the role played by mu opioid receptors in the periphery.

MX1013, a dipeptide caspase inhibitor with potent in vivo antiapoptotic activity.

1. Caspases play a critical role in apoptosis, and are considered to be key targets for the design of cytoprotective drugs. As part of our antiapoptotic drug-discovery effort, we have synthesized and characterized Z-VD-fmk, MX1013, as a potent, irreversible dipeptide caspase inhibitor. 2. MX1013 inhibits caspases 1, 3, 6, 7, 8, and 9, with IC50 values ranging from 5 to 20 nm. MX1013 is selective for caspases, and is a poor inhibitor of noncaspase proteases, such as cathepsin B, calpain I, or Factor Xa (IC50 values >10 microm). 3. In several cell culture models of apoptosis, including caspase 3 processing, PARP cleavage, and DNA fragmentation, MX1013 is more active than tetrapeptide- and tripeptide-based caspase inhibitors, and blocked apoptosis at concentrations as low as 0.5 microm. 4. MX1013 is more aqueous soluble than tripeptide-based caspase inhibitors such as Z-VAD-fmk. 5. At a dose of 1 mg kg-1 i.v., MX1013 prevented liver damage and the lethality caused by Fas death receptor activation in the anti-Fas mouse-liver apoptosis model, a widely used model of liver failure. 6. At a dose of 20 mg kg-1 (i.v. bolus) followed by i.v. infusion for 6 or 12 h, MX1013 reduced cortical damage by approximately 50% in a model of brain ischemia/reperfusion injury. 7. At a dose of 20 mg kg-1 (i.v. bolus) followed by i.v. infusion for 12 h, MX1013 reduced heart damage by approximately 50% in a model of acute myocardial infarction. 8. Based on these studies, we conclude that MX1013, a dipeptide pan-caspase inhibitor, has a good combination of in vitro and in vivo properties. It has the ability to protect cells from a variety of apoptotic insults, and is systemically active in three animal models of apoptosis, including brain ischemia.