[Efficacy and safety of VRD regimen of autologous hematopoietic stem cell transplantation in patients with newly diagnosed multiple myeloma]

Objective: To explore the stem cell collection rate and efficacy and safety of patients aged 70 and below with newly diagnosed multiple myeloma (MM) treated with the VRD (bortezomib, lenalidomide and dexamethasone) regimen followed by autologous stem cell transplantation (ASCT). Methods: Retrospective case series study. The clinical data of 123 patients with newly diagnosed MM from August 1, 2018, to June 30, 2020, at the First Affiliated Hospital of Soochow University and Suzhou Hopes Hematology Hospital, who were eligible for VRD regimen sequential ASCT, were collected. The clinical characteristics, efficacy after induction therapy, mobilization regimen of autologous stem cells, autologous stem cell collection rate, and side effects and efficacy of ASCT were retrospectively analyzed. Results: Of the 123 patients, 67 were males. The median patient age was 56 (range: 31-70) years. Patients with IgG, IgA, IgD, and light-chain types accounted for 47.2% (58/123), 23.6% (29/123), 3.2% (4/123), and 26.0% (32/123) of patients, respectively. In addition, 25.2% (31/123) of patients had renal insufficiency (creatinine clearance rate<40 ml/min). Patients with Revised-International Staging System (R-ISS) Ⅲ accounted for 18.2% (22/121) of patients. After induction therapy, the rates of partial response and above, very-good partial response (VGPR) and above, and complete response (CR)+stringent CR were 82.1% (101/123), 75.6% (93/123), and 45.5% (56/123), respectively. Overall, 90.3% (84/93) of patients were mobilized with cyclophosphamide+granulocyte colony-stimulating factor (G-CSF) and 8 patients with G-CSF or G-CSF+plerixafor due to creatinine clearance rate<30 ml/min and one of them was mobilized with DECP (cisplatin, etoposide, cyclophosphamide and dexamethasone)+G-CSF for progressive disease. The rate of autologous stem cell collection (CD34⁺cells≥2×10⁶/kg) after four courses of VRD regimen was 89.1% (82/92), and the rate of collection (CD34⁺cells≥5×10⁶/kg) was 56.5% (52/92). Seventy-seven patients treated with the VRD regimen sequential ASCT. All patients had grade 4 neutropenia and thrombocytopenia. Among the nonhematologic adverse events during ASCT, the highest incidence was observed for gastrointestinal reactions (76.6%, 59/77), followed by oral mucositis (46.8%, 36/77), elevated aminotransferases (44.2%, 34/77), fever (37.7%, 29/77), infection (16.9%, 13/77) and heart-related adverse events (11.7%, 9/77). Among the adverse events, grade 3 adverse events included nausea (6.5%, 5/77), oral mucositis (5.2%, 4/77), vomiting (3.9%, 3/77), infection (2.6%, 2/77), elevated blood pressure after infusion (2.6%, 2/77), elevated alanine transaminase (1.3%, 1/77), and perianal mucositis (1.3%, 1/77); there were no grade 4 or above nonhematologic adverse events. The proportion of patients who achieved VGPR and above after VRD sequential ASCT was 100% (75/75), and the proportion of patients who were minimal residual disease-negative (<10^-4 level) was 82.7% (62/75). Conclusion: In patients aged 70 and below with newly diagnosed MM treated with VRD induction therapy, the collection rate of autologous stem cells was good, and good efficacy and tolerability were noted after follow-up ASCT.

[Genomic epidemiology of Vibrio parahaemolyticus from acute diarrheal patients in Shenzhen City from 2013 to 2021]

Objective: To characterize the prevalence and genomic epidemiology of Vibrio parahaemolyticus from acute diarrheal patients in Shenzhen City from 2013 to 2021. Methods: Based on the Shenzhen Infectious Diarrhea Surveillance System, acute diarrheal patients were actively monitored in sentinel hospitals from 2013 to 2021. Whole-genome sequencing (WGS) of Vibrio parahaemolyticus isolates was performed, and the genomic population structure, serotypes, virulence genes and multilocus sequence typing were analyzed. Outbreak clusters from 2019 to 2021 were explored based on single-nucleotide polymorphism analysis. Results: A total of 48 623 acute diarrhea cases were monitored in 15 sentinel hospitals from 2013 to 2021, and 1 135 Vibrio parahaemolyticus strains were isolated, with a positive isolation rate of 2.3%. Qualified whole-genome sequencing data of 852 isolates were obtained. Eighty-nine serotypes, 21 known ST types and 5 new ST types were identified by sequence analysis, and 93.2% of strains were detected with toxin profile of tdh+trh-. 8 clonal groups (CGs) were captured, with CG3 as the absolute predominance, followed by CG189. The CG3 group was dominated by O3:K6 serotype and ST3 sequence type, while CG189 group was mainly O4:KUT, O4:K8 serotypes and ST189a and ST189 type. A total of 13 clusters were identified, containing 154 cases. About 30 outbreak clusters with 29 outbreak clusters caused by CG3 strains from 2019 to 2021. Conclusion: Vibrio parahaemolyticus is a major pathogen of acute infectious diarrhea in Shenzhen City, with diverse population structures. CG3 and CG189 have been prevalent and predominant in Shenzhen City for a long time. Scattered outbreaks and persistent sources of contamination ignored by traditional methods could be captured by WGS analysis. Tracing the source of epidemic clone groups and taking precise prevention and control measures are expected to significantly reduce the burden of diarrhea diseases caused by Vibrio parahaemolyticus infection in Shenzhen City.

[The expression level of secretory mature B cell surface antigen in primary diagnosed multiple myeloma and its clinical significance]

Objective: To explorer Secretory mature B cell surface antigen (sBCMA) expression level, changes during treatment and clinical significance in newly diagnosed MM patients. Methods: Clinical data of 158 MM patients admitted to the Department of Hematology, the First Affiliated Hospital of Soochow University from August 2018 to September 2020 were analyzed retrospectively. The concentration of sBCMA in the patients was determined by BCMA ELISA and compared with the normal range. The results were compared with clinical efficacy, age, type, R-ISS stage, renal impairment, and humoral immune function. Results: The median age of the patients was 57 (31-73 years old), 86 (54.5%) males and 72 (45.5%) females, mainly IgG type, 81 patients(51.2%). SBCMA value M(Q₁,Q₃) was 76.50 (55.50, 94.40) μg/L, 100% higher than the upper limit of normal value. According to the efficacy evaluation, the patients were divided into complete remission(CR) group, very good partial remission(VGPR) group, partial remission(PR) group and ineffiecacy group, the results showed the level of sBCMA in CR group[80.10 (58.05, 96.90) vs 15.70 (9.85, 28.65) μg/L] and VGPR group[74.60 (52.20, 93.00) vs 17.20 (13.30, 38.80) μg/L]was significantly higher than that before treatment(all P<0.001), and there was no significant difference in PR group and ineffective group before and after treatment (all P>0.05).The amount of serum intact protein M protein was positively correlated with the level of sBCMA expression in newly diagnosed patients (r=0.22, P=0.040), and there was no correlation between the proportion of bone marrow plasma cells and sBCMA expression (r=0.07, P=0.449).The correlation between sBCMA levels at initial diagnosis and MM type[IgG type, IgA type vs light chain type:(78.6±3.5), (72.4±5.4) vs (83.8±6.9)μg/L], age[≥65 vs<65 years: (73.6±5.5)vs (79.3±3.1)μg/L], R-ISS stage[stage Ⅰ, Ⅱ vs Ⅲ:(80.2±3.1) vs (69.4±6.1)μg/L], renal impairment [Creatinine clearance rate (Ccr) ≤30 vs>30 ml/min:(81.6±4.8) vs (76.5±3.4)μg/L], and high-risk karyotype[high-risk vs standard-risk:(73.6±5.7) vs (80.2±3.2)μg/L] were not associated (all P>0.05). Expression levels of sBCMA were negatively correlated with IgM levels in MM patients (r=-0.39, P=0.002) and after treatment (r=-0.25, P=0.015). Conclusions: The expression of sBCMA in MM patients is a reliable indicator of the clinical efficacy of MM and is related to the occurrence of MM immune deficiency and recovery after treatment. sBCMA can be used as a new independent marker for monitoring and predicting the efficacy of MM patients.

[Analysis of positive rate of sinusitis in children with head and pituitary MRI]

Objective: To investigate the incidence of asymptomatic sinusitis in children by magnetic resonance imaging. Method: Collected the head MRI of 1-12 years old children. According to the examination site,the MRI group and the pituitary MRI group (both sinus level) were included.The nasal-sinusitis-like changes in the field were used as positive criteria. Statistical analysis was conducted on the test results. Result: In 3 900 children with MRI, the positive rate of sinusitis was 30.21%. The positive rate increased from 2 years old to 3 years old and remained at the age of 11 years.The higher positive rate was slightly decreased at 12 years old; 1 228 cases of pituitary MRI examination, the positive rate of nasal-sinusitis was 38.27%, the positive rate increased significantly from the age of 2, reached the peak at 6 years old, and then fell back, still kept high positive rate, the lowest to 12 years old. The positive rate of total sinusitis was 32.14%. No obvious difference was found between two groups. Conclusion: Children's skull and pituitary MRI imaging suggests that the positive rate of nasal-innocuous sinusitis is related to age, peaking at 3 to 8 years old, and then gradually decreasing.

Characterization of Thermostable and Chimeric Enzymes via Isopeptide Bond-Mediated Molecular Cyclization

Mannooligosaccharides are released by mannan-degrading endo-β-1,4-mannanase and are known as functional additives in human and animal diets. To satisfy demands for biocatalysis and bioprocessing in crowed environments, in this study, we employed a recently developed enzyme-engineering system, isopeptide bond-mediated molecular cyclization, to modify a mesophilic mannanase from Bacillus subtilis. The results revealed that the cyclized enzymes showed enhanced thermostability and ion stability and resilience to aggregation and freeze-thaw treatment by maintaining their conformational structures. Additionally, by using the SpyTag/SpyCatcher system, we generated a mannanase-xylanase bifunctional enzyme that exhibited a synergistic activity in substrate deconstruction without compromising substrate affinity. Interestingly, the dual-enzyme ring conformation was observed to be more robust than the linear enzyme but inferior to the single-enzyme ring conformation. Taken together, these findings provided new insights into the mechanisms of molecular cyclization on stability improvement and will be useful in the production of new functional oligosaccharides and feed additives.

[Polymorphisms of mTORC1 genes and risk of primary colorectal adenocarcinoma in Chinese populations]

Objective: To study the associations between variants of mTORC1 of PI3K/AKT/mTOR pathway and colorectal cancer. Methods: In this hospital-based case-control study, at the First Affiliated Hospital, Xinjiang Medical University from 2000 to 2013, 665 primary colorectal cancer cases and 695 cancer-free controls were genotyped at 10 potentially functional single nucleotide polymorphism (SNPs) loci of mTORC1 (mTOR: rs1034528, rs2295080; Raptor: rs1062935, rs3751934; mLST8: rs3160, rs26865; DEPTOR: rs2271900, rs4871827; AKT1S1: rs2290774, rs2353005) to assess their associations with risk of colorectal cancer by Logistic regression analysis. Results: In single-locus analysis, found a significantly decreased risk of colorectal cancer associated with mLST8 rs26865 by recessive genetic model, especially in populations of ≤68 years of age (OR=0.64; 95%CI=0.43-0.96, P=0.031), female (OR=0.61; 95%CI=0.38-0.99, P=0.046), non-smoking (OR=0.55; 95%CI=0.35-0.87, P=0.010). mTOR rs1034528 CC genotypes were associated with higher risk of colorectal cancer in >68-year-old populations (OR=3.34; 95%CI=1.12-9.91, P=0.030). Raptor rs3751934 CA/AA genotypes were associated with lower colorectal cancer risk in population of body mass index(BMI)>25 kg/m(2) (OR=0.68; 95%CI=0.47-0.98, P=0.038); and AKT1S1 rs2290774 CC genotypes were associated with lower colorectal cancer risk in non-smoking population (OR=0.67; 95%CI=0.45-0.99, P=0.048). Furthermore, found that populations carrying more than two low-risk genotypes were associated with lower colorectal cancer risk, compared with that of populations carrying less than two low-risk genotypes (OR=0.74, 95%CI=0.58-0.95, P=0.017), especially in population of ≤68 years of age, male and BMI>25 kg/m(2,) and non-smoking. Conclusions: SNPs of mTORC1-related genes individually or jointly contribute to colorectal cancer susceptibility in Chinese. Further studies of larger cohorts are needed to validate the findings.

Clinical significance of fibrotic, haemostatic and endotoxic changes in patients with liver cirrhosis

BACKGROUND AND STUDY AIMS

To investigate the relationship among fibrotic, haemostatic and endotoxic changes in patients with different degrees of liver cirrhosis.

PATIENTS AND METHODS

Liver fibrotic markers, including hyaluronic acid (HA), Ccollagen IV (Col-IV), laminin (LN), and N-terminal pro-peptide of collagen type III (PIIINP), were determined by radioimmunoassay. A series of haemostatic tests, including prothrombin time (PT), international normalized ratio, activated partial thromboplastin time, antithrombin-III, thrombin time, fibrinogen, fibrin(ogen) degradation product and D-dimer were determined using an automatic coagulation analyszer. Plasma levels of endotoxin were detected quantitatively using an endotoxin detection kit. Correlation analysis of the data was performed.

RESULTS

Based on Child-Pugh classification, statistically significant differences in fibrotic markers and haemostatic parameters were found in 249 patients with liver cirrhosis, while no significant differences in endotoxin levels were observed. Based on ascites classification, statistically significant differences in fibrotic markers (such as HA, Col-IV and PIIINP, except for LN) and haemostatic parameters were found. As for endotoxin levels, there were significant differences between the ascites, spontaneous bacterial peritonitis (SBP) and no-ascites groups, while no significant differences were observed between the ascites and SBP groups. Correlation analysis demonstrated some correlation among fibrotic markers, haemostatic parameters and endotoxin.

CONCLUSIONS

A close relationship exists between the severity of cirrhosis and fibrotic changes, as well as haemostatic changes. Endotoxin may be an important contributing factor to the development of ascites in cirrhosis. Some correlation may exist between fibrosis, haemostatic and endotoxin.

[Primary central nervous system diffuse large B cell lymphoma: a clinicopathologic and molecular study]

Objective: To investigate clinicopathologic characteristics, immunophenotype and EB virus-related molecular genetic alterations in primary central nervous system diffuse large B cell lymphoma (DLBCL) along with correlation with clinical prognosis. Methods: A total of 30 cases of primary central nervous system DLBCL were retrospectively studied by retrieving clinical data, histological evaluation and immunophenotyping by EnVision two steps methods. The expression of EBER mRNA was detected by in situ hybridization and bcl-2, bcl-6 and C-MYC gene abnormalities were analyzed by interphase fluorescence in situ hybridization. Results: The cases included 18 males and 12 females (sex ratio of 1.5∶1.0) with an age ranging from 24 to 78 years (average age of 52 years, the median age of 53 years). The single primary clinical presentation was focal neurologic deficits. Tumor locations were supratentorial (21 cases), subtentorial (7 cases), involving both locations in 2 cases. Diffuse growth pattern was observed with large lymphoid cells mostly resembling centroblasts with abundant basophilic cytoplasm with oval to round, vesicular nuclei containing fine chromatin. An angiocentric and angiodestructive growth pattern was also present. Other features included perivascular space invasion. Immunohistochemical staining using a panel of CD10, bcl-6 and MUM1, six cases were germinal center-like (GCB) and 24 cases were non-germinal central-like (non-GCB). The positive rates of bcl-2, bcl-6 and C-MYC were 53.3% (16/30), 80.0% (24/30) and 20.0% (6/30), respectively. Genetic alterations were detected by FISH and the gene arrangement rates of bcl-2, bcl-6 and C-MYC were 3.3% (1/30), 16.7% (5/30) and 3.3% (1/30), respectively. There were 19 cases in stage 0-1 disease and 11 cases had stage 2-3 disease. Postoperative follow-up for average 13.6 months showed the median survival of 10 months, one-year survival of 46.7% and 16 patients died within a year. Conclusions: The clinical prognosis of primary central nerve system DLBCL depends on age, clinical performence status score, IPI score, immune classification and treatment. Patients typically progress rapidly with the high mortality within one year of diagnosis. Surgical resection combined with high-dose methotrexate or cytarabine chemotherapy offer the best treatment option.

[Role of neutrophils in treatment of rats with D-galactosamine-induced acute liver failure with bone marrow mesenchymal stem cells]

Objective: To investigate the therapeutic effect of bone marrow mesenchymal stromal cell (BMSC) transplantation on D-galactosamine-induced acute liver failure in Sprague-Dawley (SD) rats, as well as the mechanism of neutrophils in this process. Methods: A total of 39 male SD rats were divided into control group (8 rats, intraperitoneal injection of isotonic saline), model group (10 rats, intraperitoneal injection of D-galactosamine), solvent group (9 rats, tail vein injection of isotonic saline at 2 hours after intraperitoneal injection of D-galactosamine), and treatment group (12 rats, tail vein injection of MSCs at 2 hours after intraperitoneal injection of D-galactosamine). The rats were sacrificed at 24 hours after the model of D-galactosamine-induced acute liver failure was established, and the blood and liver tissue were harvested. The serum levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) and total bilirubin (TBil) were measured, and blood analysis was performed to measure the number and percentage of neutrophils in peripheral blood. Immunofluorescence assay was used to measure the expression of the neutrophil marker Ly6g in the liver, the myeloperoxidase (MPO) kit was used to measure the activity of MPO in liver, and RT-PCR was used to measure the mRNA expression of inflammatory cytokines and chemokines in the liver, i.e., tumor necrosis factor-α(TNF-α), interleukin-1β(IL-1β), interferon-γ(IFN-γ), interleukin-10 (IL-10), CXC chemokine ligand 1 (CXCL1), and CXC chemokine ligand 2 (CXCL2). Another 64 male SD rats were randomly divided into groups, and the survival rates of rats in each group were observed for 7 days. The independent samples t-test was used for comparison between any two groups (Levene homogeneity test of variance, and the corrected t-test was used for a P value of < 0.05), and the log-rank test was used for comparison of survival rates between any two groups. Results: At 24 hours after acute liver failure was induced by D-galactosamine in the SD rats, there were significant increases in the liver function parameters (ALT: 2884.1±541.0 U/L vs 45.4±11.0 U/L,P< 0.001; AST: 3634.9±755.9 U/L vs 143.9±23.7 U/L,P< 0.001; TBil: 44.4±8.4μmmol/L vs 0.9±0.2μmmol/L,P< 0.001) and the number and percentage of peripheral blood neutrophils [number: (4.7±1.1)×109 vs (1.4±0.4)×109,P< 0.001; percentage: 44.9%±8.0% vs 18.3%±4.4%,P< 0.001]. A large number of neutrophils aggregated in the liver tissue, and there were significant increases in the MPO activity (4.72±1.09 U/g vs 1.13±0.24 U/g,P< 0.001), inflammatory cytokines, and chemokines. Compared with the model group, the treatment group showed significant improvements in liver function (ALT: 1 823.9±389.2 U/L vs 2 884.1±541.0 U/L,P< 0.001; AST: 2173.0±567.3 U/L vs 3634.9±755.9 U/L,P< 0.001; TBil: 30.9±6.5μmmol/L vs 44.4±8.4μmmol/L,P< 0.001) and survival rate (50% vs 12.5%,P= 0.023). Meanwhile, the treatment group also showed significant reductions in the number and percentage of peripheral blood neutrophils [number: (3.5±1.0)×109 vs (4.7±1.1)×109,P= 0.012; percentage: 35.9%±8.9% vs 44.9%±8.0%,P= 0.021], number of neutrophils in the liver, and MPO activity (3.52±1.03 U/g vs 4.72±1.09 U/g,P= 0.040), as well as significantly inhibited expression of inflammatory cytokines and chemokines (TNF-α: 2.458±0.762 vs 3.778±1.046, P = 0.005; IL-1β: 2.498±0.547 vs 4.065 ± 0.953,P= 0.002; IFN-γ: 3.977±1.039 vs 5.418±1.255, P = 0.025; IL-10: 6.056±1.542 vs 3.368±0.952,P= 0.001; CXCL1: 7.988±1.911 vs 10.366±1.239,P= 0.010; CXCL2: 3.441±1.005 vs 4.847±1.113,P= 0.019). Conclusion: BMSC transplantation has a therapeutic effect on D-galactosamine-induced acute liver failure in rats, and this process is accompanied by reduced aggregation and activity of neutrophils in peripheral blood and liver. Inflammatory cytokines and chemokines may be involved in the mechanism of regulation of these two aspects.

SET8 expression is associated with overall survival in gastric cancer

SET8, a member of the SET domain-containing methyl-transferase, has been implicated in various biological processes. In this study, SET8 was immunostained in 100 samples of gastric cancer tissues and semi-quantified using the HSCORE method to determine the predictive value of SET8 expression levels for gastric cancer outcome. The relationship between SET8 expression and the 5-year survival rate of gastric cancer patients was assessed. High expression of SET8 was associated with a shorter survival time in gastric cancer patients, and the level of SET8 expression was found to be an independent predictor of gastric cancer outcome (relative risk = 1.939; 95% confidence interval = 1.025-3.668; P = 0.042). Analysis of SET8 levels may help in the identification of patient subgroups that are at high risk for poor disease outcomes.

Anti-platelet and anti-thrombosis characteristics of Z4A5, a novel selective platelet glycoprotein IIb/IIIa inhibitor, compared with eptifibatide under long-term infusion

Platelet Glycoprotein IIb/IIIa inhibitors are approved for the treatment of acute coronary syndromes and percutaneous coronary interventions due to their effects on the final common pathway of platelet aggregation. Z4A5 is a new hexapeptide IIb/IIIa inhibitor with antiplatelet and antithrombotic effects. This study was performed to assess the characteristics of Z4A5 compared with another IIb/IIIa inhibitor eptifibatide. Light-transmission aggregometry was used to measure platelet aggregation to assess the antiplatelet efficacy of Z4A5 in vitro and ex vivo in beagles. The time course of platelet inhibition and bleeding time prolongation during i.v. bolus plus infusion and after infusion of the Z4A5 were evaluated in beagles following two 2 x 2 Latin square designs. We also compared the antithrombotic activity of Z4A5 with eptifibatide in arterial thrombosis and arteriovenous shunt thrombosis model in beagles. Our data showed that Z4A5 completely inhibited adenosine diphosphate (ADP)-, thrombin- and arachidonic acid-induced in vitro platelet aggregation with values of IC50 of 260 nM, 128.6 and 56.4 n respectively. Z4A5 also markedly and stably prevented ADP-induced ex vivo platelet aggregation and prolonged the bleeding time throughout the 8-hour infusion. Both platelet function and bleeding time returned to normal sooner after cessation of Z4A5 infusion than after eptifibatide. Z4A5 inhibited thrombosis and had the same potent antithrombotic activity as eptifibatide. In conclusion, Z4A5 has the same potent antiplatelet effect and antithrombotic activity with the advantage of a faster on and off time compared to eptifibatide.

Weak cation magnetic separation technology and MALDI-TOF-MS in screening serum protein markers in primary type I osteoporosis

We investigated weak cation magnetic separation technology and matrix-assisted laser desorption ionization-time of flight-mass spectrometry (MALDI-TOF-MS) in screening serum protein markers of primary type I osteoporosis. We selected 16 postmenopausal women with osteoporosis and nine postmenopausal women as controls to find a new method for screening biomarkers and establishing a diagnostic model for primary type I osteoporosis. Serum samples were obtained from controls and patients. Serum protein was extracted with the WCX protein chip system; protein fingerprints were examined using MALDI-TOF-MS. The preprocessed and model construction data were handled by the ProteinChip system. The diagnostic models were established using a genetic arithmetic model combined with a support vector machine (SVM). The SVM model with the highest Youden index was selected. Combinations with the highest accuracy in distinguishing different groups of data were selected as potential biomarkers. From the two groups of serum proteins, 123 cumulative MS protein peaks were selected. Significant intensity differences in the protein peaks of 16 postmenopausal women with osteoporosis were screened. The difference in Youden index between the four groups of protein peaks showed that the highest peaks had mass-to-charge ratios of 8909.047, 8690.658, 13745.48, and 15114.52. A diagnosis model was established with these four markers as the candidates, and the model specificity and sensitivity were found to be 100%. Two groups of specimens in the SVM results on the scatterplot were distinguishable. We established a diagnosis model, and provided a new serological method for screening and diagnosis of osteoporosis with high sensitivity and specificity.

Opg/Rankl mRNA dynamic expression in the bone tissue of ovariectomized rats with osteoporosis

We established animal models of osteoporosis in ovariectomized rats to detect osteoprogerin (Opg)/receptor activator of nuclear factor-κB ligand (Rankl) mRNA expression levels in the tibias and serum estradiol concentrations at different time points. Sixty Sprague-Dawley female rats were randomly selected and divided into an ovariectomized (OVX) group and sham-operated (SHAM) group. In the SHAM group, only a small amount of abdominal fat and tissues was removed from the rats. Ten rats in each group were sacrificed at 0, 6, and 12 months after establishing the animal models (12 weeks). Opg mRNA expression and serum estradiol concentration in the OVX group were significantly lower than those in the SHAM group (P < 0.05). In contrast, Rankl mRNA expression in the OVX group was significantly higher than that in the SHAM group (P < 0.05). In the OVX group, Opg mRNA expression and serum estradiol concentrations decreased significantly from 0 to 12 months (P < 0.05), whereas Rankl mRNA expression increased significantly (P < 0.05). Opg mRNA expression and serum estradiol concentrations in the OVX group continually decreased, whereas Rankl mRNA expression continually increased. The Opg/Rankl ratio showed a decrease. The OPG/RANKL ratio may be a key factor affecting the osteoblast-mediated reaction.

Possible anticipation in familial epidermolytic palmoplantar keratoderma with the p.R163W mutation of Keratin 9

Epidermolytic palmoplantar keratoderma (EPPK) is an autosomal dominant disease characterized by diffuse hyperkeratosis of the epidermis of the palm and sole with an erythematous margin. The Keratin 9 (KRT9) and Keratin 1 genes are responsible for EPPK. Several previous studies have focused on the genetic basis of EPPK; however, genetic anticipation has not yet been reported. We described a four-generation family with EPPK and identified a p.R163W mutation of KRT9. We observed a decrease in the age of onset in three consecutive generations in the family of the proband, indicating possible genetic anticipation in this familial EPPK. Further studies are needed to elucidate the mechanisms of anticipation in EPPK.

Drynaria total flavonoids decrease cathepsin K expression in ovariectomized rats

This study investigated the effects of Drynaria total flavonoids on cathepsin K serum concentrations and gene expression, biomechanics and bone mineral density (BMD) of the tibial shaft in ovariectomized rat models of osteoporosis, and mechanism in the prevention and cure of osteoporosis. Seventy-two female Sprague-Dawley rats were divided into six groups. The rats in each group were subjected to gastric lavage after the model was established. The tibial shaft of the right hindlimb was obtained to measure the BMD. Serum cathepsin K concentrations were determined. The cathepsin K mRNA expression was also determined using fluorescent quantitative polymerase chain reaction. The three-point bending method was performed to measure the maximum bending load of the tibial shaft. The total flavonoid and normal groups had significant differences in serum cathepsin K concentrations compared with that in the estrogen group (P<0.05). The total flavonoid and sham-operated groups also showed significant differences in cathepsin K mRNA expression compared with that in the normal group (P<0.01). The maximum bending load of the rats in the total flavonoid group was significantly different from that in the estrogen group (P<0.05) and the sham-operated and normal groups (P<0.01). The high-dose total flavonoid group elicited a better effect on BMD than that by the medium- and low-dose groups (P<0.05). Thus, Drynaria total flavonoids inhibited the serum cathepsin K concentration and increased the maximum bending load of the tibial shaft in ovariectomized rats.

Review of chromium (VI) apoptosis, cell-cycle-arrest, and carcinogenesis

Hexavalent chromium combines with glutathione in chloride intracellular channel carrier to form tetravalent and pentavalent chromium in plasma and organelle membranes. It also combines with NADH/NADPH to form pentavalent chromium in mitochondria. Tetravalent- and pentavalent- chromium (directly and indirectly) mediated DNA double strand breaks activate DNA damage signaling sensors: DNA-dependent-protein-kinase signals p53-dependent intrinsic mitochondrial apoptosis, and ataxia-telangiectasia-mutated and ataxia-telangiectasia-Rad3-related signal cell-arrest for DNA repair. Tetravalent chromium may be the most potent species since it causes DNA breaks and somatic recombination, but not apoptosis. Upon further failure of apoptosis and senescence/DNA-repair, damaged cells may become immortal with loss-of-heterozygosity and genetic plasticity.

Effect of reflux ratio on COD and nitrogen removals from coke plant wastewaters

A laboratory-scale anaerobic-anoxic-aerobic-moving bed biofilm reactor (A1-A2-O-MBBR) system was undertaken to treat coke plant wastewaters from two different factories (wastewater A and B). Wastewater B had higher BOD5/COD ratio and COD/TN ratio than wastewater A. The effects of reflux ratios on COD, TN and NH3-N removals were studied. Results indicated that, with the reflux ratio increased from 2 to 5, COD removals of wastewater A and wastewater B increased from 57.4% to 72.6% and 78.2% to 88.6%, respectively. Meanwhile, TN removals were also increased accompanying reflux ratio rise, from 53.1% to 74.4% for wastewater A and 64.2% to 83.5% for wastewater B. At the same reflux ratio, compared with wastewater A, higher COD and TN removal efficiencies were observed in wastewater B, which had higher BOD5/COD and COD/TN ratio. Reflux ratio had no significant influence on NH3-N removal; 99.0% of the overall NH3-N removal efficiency was achieved by the system for both coke plant wastewaters at any tested reflux ratio. MBBR was effective in NH3-N removal, and about 95% of the NH3-N was removed in the MBBR.

Mutation L437P in the 2B domain of keratin 1 causes diffuse palmoplantar keratoderma in a Chinese pedigree

Diffuse palmoplantar keratoderma (DPPK) is an autosomal dominant genodermatosis characterized by uniform hyperkeratosis of the palm and sole epidermis. This disorder can be caused by mutations in the genes keratin 1, keratin 9, keratin 16, desmoglein 1 and plakoglobin. Here we present a DPPK Chinese pedigree and identify the aetiology as a novel missense mutation, L437P, located in a highly conserved helix motif in domain 2B of KRT1. Functional analysis shows that overexpression of the L437P mutant in cultured cells leads to abnormal intermediate filament networks and filament aggregation. This gain-of-function mutation highlights the role of domain 2B in mediating filament assembly.

[Study on analysis of concentration of surfactant PS in injected-produced liquor used in ASP flooding with HPLC]

Ion exchanger and ODS bonded silica gel for HPLC packing were prepared. An HPLC method for the analysis of surfactant PS concentration in injected-produced liquor has been established to meet the need of ASP flooding developed in Gudao West Block of Shengli Oilfield, with a minimum detectable limit of 0.4 mg/L, a linear range of 50 mg/L-1,000 mg/L and recoveries of 95.7%-99.8%. This method has provided great technical support in a variety of fields to the design of the prescription for ASP flooding, the regulation of injection measurement, the quality control of products and the study on the mechanism of oil flooding etc.

Silica-induced pulmonary inflammation in rats: activation of NF-kappa B and its suppression by dexamethasone

The goal of this study was to examine the relationship of the transcriptional regulatory factor nuclear factor-kappaB (NF-kappa B) to the early inflammatory events involved with silica exposure. Male F-344 rats received an intratracheal (i.t.) instillation of silica (100 mg/kg in a volume of 1 ml/kg) of saline. At 1, 3, 6, and 18 h postinstillation, and the rats were sacrificed and underwent bronchoalveolar lavage (BAL) for functional analysis of inflammation. Beginning at 1 h postinstillation, the silica-instilled (Si) rats displayed significant increases in neutrophils in BAL fluid compared to the saline controls. BAL cells from the Si group displayed a significant increase in luminol-dependent chemiluminescence (LDCL) compared to the controls. NF-kappa B activation was measurable at 3 h postinstillation, and this activation continued throughout the 18-h time course. Treatment with dexamethasone (5 mg/kg) at -3 h prior to silica instillation, at the time of instillation (0 h), and +1.5 h postinstillation resulted in both a reduction in NF-kappa B expression (by 70%) at 3 h postinstillation and corresponding reductions in LDCL, BAL cell count, and BAL neutrophils. These results show that activation of NF-kappa B is associated with silica-induced pulmonary inflammation, and the inhibition of its activation correlates temporally with suppression of inflammation.

Mutations in the gene encoding gap junction protein beta-3 associated with autosomal dominant hearing impairment

Hearing impairment is the most commonly occurring condition that affects the ability of humans to communicate. More than 50% of the cases of profound early-onset deafness are caused by genetic factors. Over 40 loci for non-syndromic deafness have been genetically mapped, and mutations in several genes have been shown to cause hearing loss. Mutations in the gene encoding connexin 26 (GJB2) cause both autosomal recessive and dominant forms of hearing impairment. To study the possible involvement of other members of the connexin family in hereditary hearing impairment, we cloned the gene (GJB3) encoding human gap junction protein beta-3 using homologous EST searching and nested PCR. GJB3 was mapped to human chromosome 1p33-p35. Mutation analysis revealed that a missense mutation and a nonsense mutation of GJB3 were associated with high-frequency hearing loss in two families. Moreover, expression of Gjb3 was identified in rat inner ear tissue by RT-PCR. These findings suggest that mutations in GJB3 may be responsible for bilateral high-frequency hearing impairment.

Synergistic activation of transcription by CBP and p53

The tumour suppressor p53 is a transcriptional regulator whose ability to inhibit cell growth is dependent upon its transactivation function. Here we demonstrate that the transcription factor CBP, which is also implicated in cell proliferation and differentiation, acts as a p53 coactivator and potentiates its transcriptional activity. The amino-terminal activation domain of p53 interacts with the carboxy-terminal portion of the CBP protein both in vitro and in vivo. In transfected SaoS-2 cells, CBP potentiates activation of the mdm-2 gene by p53 and, reciprocally, p53 potentiates activation of a Gal4-responsive target gene by a Gal4(1-147)-CBP(1678-2441) fusion protein. A double point mutation that destroys the transactivation function of p53 also abolishes its binding to CBP and its synergistic function with CBP. The ability of p53 to interact physically and functionally with a coactivator (CBP) that has histone acetyltransferase activity and with components (TAFs) of the general transcription machinery indicates that it may have different functions in a multistep activation pathway.

[The effect of stimulation and toxicity of rhizoma Pinelliae processed by ginger juice on animals]

Rhizoma Pinelliae boiled with ginger juice has less stimulation and toxicity on animals, which is similar to Rhizoma Pinelliae processed by alum solution. The effect of Rhizoma Pinelliae that has been immersed in ginger juice is not as good as that of the ginger-boiled. It was also observed that the stimulation of raw Rhizoma Pinelliae on mice could be reduced when the mice was given fresh or boiled ginger juice. The Rhizoma Pinelliae processed by ginger juice and alum has very little toxicity on mice.

The role of superoxide radical in chromium (VI)-generated hydroxyl radical: the Cr(VI) Haber-Weiss cycle

To understand the role of the superoxide (O-2) radical in chromate-related genotoxicity, we investigated whether Cr(VI) can catalyze the Haber-Weiss cycle in vitro: O-2 + Cr(VI)----Cr(V) + O2 Cr(V) + H2O2----Cr(VI) + .OH + OH-. ESR and spin trapping techniques were utilized to monitor the O-2 (produced using xanthine/xanthine oxidase), .OH, and Cr(V) species. Superoxide dismutase as well as catalase inhibited the .OH radical radical formation, attesting to the direct involvement of O-2 and H2O2 in the process. ESR measurements also provided direct evidence for the formation of Cr(V). Kinetic measurements were consistent with the role of Cr(V) and H2O2 as intermediates in .OH formation. These results indicate that in cellular media, especially during chromate phagocytosis, the O-2 radical can become a significant source of .OH radicals and hence a significant factor in the biochemical mechanism of cellular damage due to Cr(VI) exposure.

One-electron reduction of carcinogen chromate by microsomes, mitochondria, and Escherichia coli: identification of Cr(V) and .OH radical

Earlier studies have shown that a long-lived Cr(V) species is produced during the reduction of chromate (Cr(VI] by microsomes/NADPH, mitochondria, and other cellular constituents and that this Cr(V) species plays a significant role in the mechanism of Cr(VI) toxicity. The present work indicates that this species is a Cr(V) complex involving the diol moieties of NADPH as the ligand. Additionally, ESR spin trapping investigations show that the hydroxyl (.OH) radical is also generated in the reduction process. Hydrogen peroxide (H2O2) enhances the .OH generation but suppresses the Cr(V)-NADPH complex formation. Catalase decreases the .OH radical generation and enhances the Cr(V)-NADPH formation. Measurements under anaerobic atmosphere show decreased .OH radical generation, indicating that during the cellular Cr(VI) reduction process molecular oxygen is reduced to H2O2, which reacts with the Cr(V)-NADPH complex to generate the .OH radical via a Fenton-like mechanism.

Flavoenzymes reduce vanadium(V) and molecular oxygen and generate hydroxyl radical

ESR spectroscopic evidence is presented for the formation of vanadium(IV) in the reduction of vanadium(V) by three typical, NADPH-dependent, flavoenzymes: glutathione reductase, lipoyl dehydrogenase, and ferredoxin-NADP+ oxidoreductase. The vanadium(V)-reduction mechanism appears to be an enzymatic one-electron reduction process. Addition of superoxide dismutase (SOD) showed that the generation of vanadium(IV) does not involve the superoxide (O2-) radical significantly. Measurements under anaerobic atmosphere showed, however, that the enzymes-vanadium-NADPH mixture can cause the reduction of molecular oxygen to generate H2O2. The H2O2 and vanadium(IV) thus formed react to generate hydroxyl (.OH) radical. The .OH formation is inhibited strongly by catalase and to a lesser degree by SOD, but it is enhanced by exogenous H2O2, suggesting the occurrence of a Fenton-like reaction. The inhibition of vanadium(IV) formation by N-ethylmaleimide indicates that the SH group on the flavoenzyme's cystine residue plays an important role in the enzyme's vanadium(V) reductase function. These results thus reveal a new property of the above-mentioned, NADPH-dependent flavoenzymes--their function as vanadium(V) reductases, as well as that as generators of .OH radical in the vanadium(V) reduction mechanism.

8-Hydroxy-2'-deoxyguanosine formation during the catalytic oxidation of hydrazines in the presence of 2'-deoxyguanosine

The reaction of 2'-deoxyguanosine (1), substituted hydrazines (Hy) and oxygen, in the presence of Cu(II) as catalyst, yields 8-hydroxy-2'-deoxyguanosine (2). The rate of formation of 2 was found to be dependent upon the oxidation potential of the Hy and on structural factors of the Hy. The conversion of 1 to 2 under these conditions suggested that a Haber-Weiss/Fenton type of process was involved with Hy acting as reductant. However, the dependence of the rate of the conversion of 1 to 2 upon the structure of Hy suggested that the Hy substrates studied may be more directly involved in the process than that of a reducing agent. Additional studies of this reaction system, including the oxygen consumption, radical trapping studies and direct ESR measurements suggest that the conversion of 1 to 2, under the conditions used, involves the intermediacy of complex composed of the metal catalyst, 1, Hy and oxygen. The rate data for the conversion of 1 to 2 appear to be correlated with the carcinogenicity of Hy and therefore 2 may be an important DNA adduct in the carcinogenesis of hydrazines.

NADPH-dependent flavoenzymes catalyze one electron reduction of metal ions and molecular oxygen and generate hydroxyl radicals

This study reports a new property of the important NAD(P)H-dependent flavoenzymes, glutathione reductase, lipoyl dehydrogenase and ferredoxin-NADP+ oxidoreductase, that can catalyze a one electron reduction of metal ions such as chromium(VI) and vanadium(V). During the enzymatic reduction process, molecular oxygen is reduced to H2O2, which reacts with the reduced metal complexes to generate hydroxyl radicals. Since the hydroxyl radicals have been suggested to play an important role in Cr(VI) toxicity, this study provides a basis for a recent observation that Cr(VI) mutagenesis is strongly oxygen dependent. These results also point to an enzymatic pathway for the metabolism of some metal ions and concomitant generation of hydroxyl radicals.

The glutathionyl radical formation in the reaction between manganese and glutathione and its neurotoxic implications

Electron spin resonance (ESR) spin trapping methodology has been used to study the reactions of manganese dusts with glutathione, employing alpha-(4-pyridyl-1-oxide)-N-tert-butyl-nitrone (PBN) and 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) as spin traps. The results show evidence for the glutathionyl radical formation in the reactions of both MnO2 and manganese (III) acetate with glutathione. Based on these experimental observations, we hypothesise that the mechanism of neurotoxic effects of manganese might be due to the fact that the generation of glutathionyl radicals depletes the glutathione pool and reduces the glutathione shield against free radical products of dopamine metabolism and manganese induced reactive oxygenated species.

Reaction of vanadium(V) with thiols generates vanadium (IV) and thiyl radicals

The in vivo toxicity of vanadium(V) has been found to correlate with the depletion of cellular glutathione and related non-protein thiols. With a view to understanding the mechanism for this observation, we have investigated the oxidation of glutathione, cysteine N-acetylcysteine and penicillamine by vanadium(V), using electron spin resonance (ESR) and ESR spin trapping methodology. The spin trap used was 5,5-dimethyl-1-pyrroline 1-oxide (DMPO). It is found that the oxidation of these thiols by vanadium(V) generates the corresponding thiyl radicals and vanadium- (IV) complexes. The results suggest that free radical reactions play a significant role in the depletion of cellular thiols by vanadium(V) and hence in vanadium(V) toxicity.

One-electron reduction of chromate by NADPH-dependent glutathione reductase

Electron spin resonance (ESR) measurements provide evidence for the formation of Cr(V) intermediates in the enzymatic reduction of Cr(VI) by glutathione reductase (GSSG-R) in the presence of NADPH, indicating an initial single-electron transfer step in the reduction mechanism. Depending on the pH, at least two different Cr(V) species are generated which are relatively long-lived. In addition, we have detected the hydroxyl (.OH) radical formation during the GSSG-R catalyzed reduction of Cr(VI) by spin trapping, employing 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) and alpha-(4-pyridyl-1-oxide)-N-tert-butylnitrone (4-POBN) as spin traps. Superoxide dismutase (SOD) causes only a minor effect on the .OH radical and Cr(V) formation, indicating that the O2- is not significantly involved in the reaction mechanism. Catalase enhances the Cr(V) formation and substantially inhibits the .OH radical formation, indicating the involvement of hydrogen peroxide (H2O2) in the reaction mechanism. Addition of H2O2 suppresses Cr(V) and enhances the .OH radical formation. Measurements involving N-ethylmaleimide show that the Cr(V) species, produced enzymatically by the reduction of Cr(VI) by GSSG-R, react with H2O2 to generate .OH radicals, which might participate in the initiation of Cr(VI) carcinogenicity.

Evidence for a Fenton-type mechanism for the generation of .OH radicals in the reduction of Cr(VI) in cellular media

Electron spin resonance (ESR) spectroscopy has been employed to examine the role of tetraperoxochromate (V) ions (CrO3-8) and other Cr(V) species in the generation of hydroxyl (OH) radicals in the reaction of Cr(VI) with H2O2 in biological media. In contrast to earlier suggestions, the present ESR studies using crystalline K3CrO8 as a source of CrO3-8 show that decomposition of CrO3-8 in water or in H2O2 does not generate significant amounts of OH radicals. Addition of NADH to a solution containing CrO3-8 yields a Cr(V)-NADH complex, which readily reacts with H2O2 to generate OH radicals. Similar results obtained from several other biological reductants, including vitamin B2, indicate that a vacant coordination site on a Cr(V) complex facilitates its reaction with H2O2 to generate .OH radicals. We thus suggest that in biological media, reaction [3] instead of [1] or [2] is the major pathway for the .OH radical generation: [formula, see text]

Glutathione reductase functions as vanadate(V) reductase

The oxidation of NADPH by vanadate(V) in the presence of glutathione reductase showed typical enzymatic kinetics. The oxidation was inhibited by N-ethylmaleimide, a glutathione reductase inhibitor. Superoxide dismutase had no significant effect on the oxidation, indicating noninvolvement of the superoxide radical. The vanadate(V) reduction was found to be a one-electron transfer process. These results suggest a new pathway for vanadate(V) metabolism and a new function of glutathione reductase.

Role of free radicals in the mechanisms of hemolysis and lipid peroxidation by silica: comparative ESR and cytotoxicity studies

Electron spin resonance (ESR) and cytotoxicity measurements were made on newly fractured silica to examine specifically the role of the fracture-induced, silicon-based radicals (Si. and SiO.) and silica-generated hydroxyl (.OH) radicals in the mechanism of the cell membrane damage by silica. The concentration of the Si. and SiO. radicals was controlled through decay processes, thermal annealing, and boiling, while that of the .OH radicals was varied by using catalase, superoxide dismutase, KMnO4, Na2SeO3, ascorbic acid, and metal ions, and monitored via ESR spectroscopy. The dust's cytotoxicity potential was evaluated by measuring the silica-induced hemolysis and also by determining lipid peroxidation (using linoleic acid). From the comparison of hemolysis and ESR results it is deduced that the radicals play little or no role in the silica-induced hemolysis. However, the lipid peroxidation data indicate that the radicals might be involved in the initiation of an oxidative chain reaction leading to the macrophage membrane damage through lipid peroxidation.

ESR spin trapping detection of hydroxyl radicals in the reactions of Cr(V) complexes with hydrogen peroxide

Electron spin resonance (ESR) measurements provide direct evidence for the involvement of Cr(V) in the reduction of Cr(VI) by NAD(P)H. Addition of hydrogen peroxide (H2O2) to NAD(P)H-Cr(VI) reaction mixtures suppresses the Cr(V) signal and generates hydroxyl (.OH) radicals (as detected via spin trapping), suggesting that Cr(V) reacts with H2O2 to generate the .OH radicals. Reaction between H2O2 and a Cr(V)-glutathione complex, and between H2O2 and several Cr(V)-carboxylato complexes also produces .OH radicals. These results suggest that Cr(V) complexes catalyze the generation of .OH radicals from H2O2, and that .OH radicals might play a significant role in the mechanism of Cr(VI) cytotoxicity.

ESR spin trapping and cytotoxicity investigations of freshly fractured quartz: mechanism of acute silicosis

Electron spin resonance (ESR) measurements show that grinding of quartz particles in air produces silicon-based (Si. and SiO.) radicals which decay with aging in air. ESR spin trapping measurements provide evidence for the generation of hydroxyl and possibly superoxide radicals from a suspension of fresh quartz particles. The hydroxyl radical generation potential of the fresh quartz particles decreases on storing in ambient air and on the addition of catalase, superoxide dismutase, desferroxamine, or DMSO. Silica-induced lipid peroxidation also decreases on storing the fresh particles in ambient air. These findings suggest that oxygenated radicals play a role in the biochemical mechanism of pneumoconiosis in general and acute silicosis in particular.

Chromium (V) and hydroxyl radical formation during the glutathione reductase-catalyzed reduction of chromium (VI)

Electron spin resonance measurements provide evidence for the formation of long-lived Cr(V) intermediates in the reduction of Cr(VI) by glutathione reductase in the presence of NADPH and for the hydroxyl radical formation during the glutathione reductase catalyzed reduction of Cr(VI). Hydrogen peroxide suppresses Cr(V) and enhances the formation of hydroxyl radicals. Thus Cr(V) intermediates catalyze generation of hydroxyl radicals from hydrogen peroxide through a Fenton-like reaction. Thus the mechanism of Cr(VI) toxicity might involve the interaction between macromolecules and the hydroxyl radicals.

The chemical properties of silica particle surface in relation to silica-cell interactions

Although silicosis has been studied extensively, the mechanism is still not fully understood. Experiments do provide evidence that the actions of unique properties of silica surface on the cell membrane are the starting point of silicotic processes. This paper summarizes literature on chemical properties of silica surface, and the effect of particle size on silica toxicity. This paper also discusses the ways in which silica dusts are thought to interact with the cell membrane, with emphasis on freshness, hydrogen bonding, and free-radical interactions.

On the formation of oxygenated radicals by fredericamycin A and implications to its anticancer activity: an ESR investigation

It has been recently suggested that the exceptionally high antitumor and antibacterial activity of natural fredericamycin A (FMA) is related to its ability to spontaneously generate the superoxide anion (O2-) and hydroxyl (.OH) radicals in aerobic solutions [Hilton, B. D., Misra, R., & Zweier, J. L. (1986) Biochemistry 25, 5533]. With a view to understand the mechanistic details, attempts were made to reproduce earlier electron spin resonance (ESR) evidence for the oxygenated free radical formation in well-aerated solutions of natural FMA in dimethyl sulfoxide and dilute H2O2. Little or no evidence was obtained for the formation of the O2- and methoxy (.OCH3) radicals, while the detected formation of the .OH and methyl (.CH3) radicals was attributable largely to mechanisms not involving FMA. These results thus reopen the question regarding the mechanism of its exceptionally high tumoricidal-bacteriocidal activity.

Generation of free radicals from freshly fractured silica dust. Potential role in acute silica-induced lung injury

Data presented here indicate that freshly fractured silica exhibits surface characteristics and biologic reactivity distinct from aged silica, and on this basis we propose that these surface features may lead to enhanced manifestations of lung injury. Grinding of silica produces approximately 10(18) Si and Si-O (silicon-based) radicals per gram of dust on the particulate surface which are characterized by an electron spin resonance (ESR) spectrum centered around g = 2.0015. These silicon-based radicals react with aqueous media to produce OH radicals, which are demonstrable using a DMPO spin trap. The concentration of silicon-based radicals in silica decreases with aging in air and exhibits a half-life of approximately 30 h, whereas its ability to generate OH radicals in aqueous solution decreases with a half-life of approximately 20 h. However, on storage in aqueous media, the concentration of silicon-based radicals and the dust's ability to generate OH radicals decrease significantly within a few minutes. Freshly ground silica is also more biologically reactive than aged silica, because freshly crushed silica activates a greater respiratory burst in alveolar macrophages than aged silica, i.e., storage of ground dust in air decreases silica-induced superoxide anion secretion, hydrogen peroxide release, and NBT reduction by 25%, 68%, and 43%, respectively. Furthermore, compared to aged silica, freshly ground silica exhibits a greater cytotoxic effect on cellular membrane integrity, i.e., a 1.5-fold increase in LDH release from macrophages, a 36-fold increase in hemolytic activity, and a three-fold increase in the ability to induce lipid peroxidation.(ABSTRACT TRUNCATED AT 250 WORDS)

On the mechanism of the chromate reduction by glutathione: ESR evidence for the glutathionyl radical and an isolable Cr(V) intermediate

With a view of elucidating the role of glutathione (GSH) in the biochemical pathways of the chromate-exposure related carcinogenesis, we carried out electron spin resonance (ESR) spectroscopic investigations of the chromate-GSH redox reactions. The ESR measurements, employing spin-traps, provide evidence for the involvement of the glutathione (GS) radical, as well as an isolable Cr(V)-glutathione intermediate. These results indicate a new mechanism for the reduction of chromate by GSH in in vitro cellular environment and help understand the (unexpected) increase in Cr(VI)-induced DNA strand breaks at elevated GSH levels.

ESR evidence for the hydroxyl radical formation in aqueous suspension of quartz particles and its possible significance to lipid peroxidation in silicosis

Electron spin resonance (ESR) spectrum of the hydroxyl (.OH) radical spin adduct with the spin trap 5,5-dimethyl-1-pyrroline-N-oxide has been obtained in suspensions of freshly ground quartz particles. The concentration of the spin adduct (and hence of the .OH radicals) increases with the amount of grinding. The dust's potential for the generation of the .OH radicals is maximum when fresh (i.e., immediately after grinding) and decreases to 50% in about a day on storage in air. Studies involving metal chelates indicate that the .OH radical formation involves mainly the silica surface and H2O rather than the Fenton reaction. The results suggest that hydroxyl radical reaction(s) could be important in the lipid peroxidation and fibrogenicity by quartz dust, particularly in acute silicosis.