Epidemiological updates of post-traumatic related limb osteomyelitis in china: a 10 years multicentre cohort study

BACKGROUND

Post-traumatic related limb osteomyelitis (PTRLO) is a complex bone infection. Currently, there are no available microbial data on a national scale that can guide appropriate antibiotic selection, and explore the dynamic changes in dominant pathogens over time. This study aimed to conduct a comprehensive epidemiological analysis of PTRLO in China.

METHODS

The study was approved by the Institutional Research Board (IRB), and 3526 PTRLO patients were identified from 212 394 traumatic limb fracture patients at 21 hospitals between 1 January 2008 and 31 December 2017. A retrospective analysis was conducted to investigate the epidemiology of PTRLO, including changes in infection rate (IR), pathogens, infection risk factors and antibiotic resistance and sensitivity.

RESULTS

The IR of PTRLO increased gradually from 0.93 to 2.16% (Z=14.392, P <0.001). Monomicrobial infection (82.6%) was significantly higher than polymicrobial infection (17.4%) ( P <0.001). The IR of Gram-positive (GP) and Gram-negative (GN) pathogens showed a significant increase from the lowest 0.41% to the highest 1.15% (GP) or 1.62% (GN), respectively. However, the longitudinal trend of GP vs. GN's composition did not show any significance (Z=±1.1918, P >0.05). The most prevalent GP strains were Methicillin-sensitive Staphylococcus aureus (MSSA) (17.03%), Methicillin-resistant Staphylococcus aureus (MRSA) (10.46%), E. faecalis (5.19%) and S. epidermidis (4.87%). In contrast, the dominant strains GN strains were Pseudomonas Aeruginosa (10.92%), E. cloacae (10.34%), E. coli (9.47%), Acinetobacter Baumannii (7.92%) and Klebsiella Pneumoniae (3.33%). In general, the high-risk factors for polymicrobial infection include opened-fracture (odds ratio, 2.223), hypoproteinemia (odds ratio, 2.328), and multiple fractures (odds ratio, 1.465). It is important to note that the antibiotics resistance and sensitivity analysis of the pathogens may be influenced by complications or comorbidities.

CONCLUSIONS

This study provides the latest data of PTRLO in China and offers trustworthy guidelines for clinical practice. (China Clinical Trials.gov number, ChiCTR1800017597).

Major adverse cardiovascular events associated with testosterone treatment: a pharmacovigilance study of the FAERS database

Background and purpose: Testosterone is an essential sex hormone in maintaining masculine characteristics, which is prescribed for male hypogonadism as testosterone replacement treatment (TRT). Herein, we investigated long-standing controversies about the association between TRT and major adverse cardiovascular events (MACEs), based on real world adverse event (AE) reports, registered in the Food and Drug Administration Adverse Event Reporting System (FAERS). Methods: Publicly available FAERS data from 1 January 2004 to 31 December 2022 were retrieved from the Food and Drug Administration (FDA) website. The data mining protocol including the reporting odds ratio (ROR) and the Bayesian confidence propagation neural network (BCPNN) was applied to analyze overreporting caused by risk factors and MACEs, including TRT, morbidities, and ages. The ROR and the BCPNN were also applied to investigate the annually developing trend of pharmacovigilance (PV) signals in the real world, retrospectively. Results: A total of 3,057 cases referring to MACEs, with a median age of 57 years old (yo), were identified from 28,921 cases of testosterone users. MACEs related to PV signals have emerged since 2014, including cardiac death, non-fatal myocardial infarction, and non-fatal stroke. Myocardial infarction (MI) (ROR: 9.46; IC₀₂₅: 3.08), acute myocardial infarction (AMI) (ROR: 16.20; IC₀₂₅: 3.72), ischemic cardiomyopathy (ROR: 11.63; IC₀₂₅: 2.20), and cardiomyopathy (ROR: 5.98; IC₀₂₅: 1.96) were the most significant signals generated, and weaker signals included cardiac failure acute (ROR: 4.01; IC₀₂₅: 0.71), cardiac arrest (ROR: 1.88; IC₀₂₅: 0.56), and ventricular fibrillation (VF) (ROR: 2.38; IC₀₂₅: 0.38). The time-to-onset (TTO) of MACEs was calculated with a median of 246 days for AMI. Conclusion: For myocardial infarction and cardiomyopathy, TRT statistically tended to increase the risk of MACEs, while for cardiac arrhythmia, cardiac failure, and stroke, TRT demonstrated beneficial effects among the population with morbidities, such as testosterone deficiency (TD), diabetes mellitus (DM), and hypertension. MACEs were rare but led to serious outcomes including significant increase in death and disability. Since 2018, and before 2014, reports referring to TRT associated with MACEs were relatively scarce, which indicated that there might be a considerable number of cases that went unrecorded, due to neglection. Health workers and testosterone users might pay more attention to testosterone-induced MACEs.

[Natural history of chronic hepatitis B virus infection under low-level viremia]

Low-level viremia (LLV) is a hot and difficult topic that has gradually attracted attention in the field of chronic hepatitis B for evaluating antiviral therapy response in recent years. The presence of LLV may increase drug-resistant mutations, the progression of liver fibrosis, and potentially the development of liver cancer following antiviral therapy. Natural history of chronic HBV infection patients also have LLV, but it is unclear whether these patients are also at risk of disease progression, what the risk is, and whether early antiviral therapy is necessary and beneficial. Therefore, this article provides a reference for the all-encompassing management of this group of patients by reviewing the prevalence and impact of LLV in chronically HBV-infected patients' natural histories.

Sodium-glucose co-transporter-2 inhibitor (SGLT2i) treatment and risk of osteomyelitis: A pharmacovigilance study of the FAERS database

Background and purpose: Several clinical trials have indicated that the use of canagliflozin increases the risk of lower extremity amputation. Although the US Food and Drug Administration (FDA) has withdrawn its black box warning about amputation risk for canagliflozin, the risk still exists. We sought to estimate the association between hypoglycemic medications, especially sodium-glucose co-transporter-2 inhibitors (SGLT2is), and adverse events (AEs) before the irreversible outcome of amputation as a promising early warning, based on the FDA Adverse Event Reporting System (FAERS) data. Methods: Publicly available FAERS data were analyzed using a reporting odds ratio (ROR) method and validated by a Bayesian confidence propagation neural network (BCPNN) method. The developing trend of the ROR was investigated by a series of calculations based on the accumulation of data in the FAERS database quarter by quarter. Results: Ketoacidosis, infection, peripheral ischemia, renal impairment, and inflammation including osteomyelitis might be more likely to occur among users of SGLT2is, especially canagliflozin. Osteomyelitis and cellulitis are AEs unique to canagliflozin. Among 2,888 osteomyelitis-related reports referring to hypoglycemic medications, 2,333 cases were associated with SGLT2is, with canagliflozin accounting for 2,283 of these cases and generating an ROR value of 360.89 and a lower limit of information component (IC₀₂₅) of 7.79. No BCPNN-positive signal could be generated for drugs other than insulin and canagliflozin. Reports suggesting that insulin could generate BCPNN-positive signals span from 2004 to 2021, whereas reports with BCPNN-positive signals emerged only since the second quarter (Q2) of 2017, 4 years since the approval of SGLT2is in Q2 of 2013, for canagliflozin and drug groups containing canagliflozin. Conclusion: This data-mining investigation revealed a strong association between canagliflozin treatment and developing osteomyelitis that might be a crucial forewarning to lower extremity amputation. Further studies with updated data are needed to better characterize the risk of osteomyelitis associated with SGLT2is.

Serious adverse reaction associated with the COVID-19 vaccines of BNT162b2, Ad26.COV2.S, and mRNA-1273: Gaining insight through the VAERS

Background and purpose: Serious adverse events following immunization (AEFI) associated with the COVID-19 vaccines, including BNT162b2 (Pfizer-BioNTech), Ad26.COV2.S (Janssen), and mRNA-1273 (Moderna), have not yet been fully investigated. This study was designed to evaluate the serious AEFI associated with these three vaccines. Methods: A disproportionality study was performed to analyze data acquired from the Vaccine Adverse Event-Reporting System (VAERS) between 1 January 2010 and 30 April 2021. The reporting odds ratio (ROR) method was used to identify the association between the COVID-19 vaccines BNT162b2, Ad26.COV2.S, and mRNA-1273 and each adverse event reported. Moreover, the ratio of the ROR value to the 95% CI span was applied to improve the credibility of the ROR. The median values of time from vaccination to onset (TTO) for the three vaccines were analyzed. Results: Compared with BNT162b2 and mRNA-1273, Ad26.COV2.S vaccination was associated with a lower death frequency (p < 0.05). Ad26.COV2.S vaccination was associated with a lower birth defect and emergency room visit frequency than BNT162b2 (p < 0.05). There were 6,605, 830, and 2,292 vaccine recipients who suffered from COVID-19-related symptoms after vaccination with BNT162b2, Ad26.COV2.S, and mRNA-1273, respectively, including people who were infected by COVID-19, demonstrated a positive SARS-CoV-2 test, and were asymptomatic. Serious AEFI, including thromboembolism, hemorrhage, thrombocytopenia, cardiac arrhythmia, hypertension, and hepatotoxicity, were associated with all three vaccines. Cardiac failure and acute renal impairment events were associated with BNT162b2 and mRNA-1273, while seizure events were associated with BNT162b2 and Ad26.COV2.S. The median values of TTO associated with the three vaccinations were similar. Conclusion: These findings may be useful for health workers and the general public prior to inoculation, especially for patients with underlying diseases; however, the risk/benefit profile of these vaccines remains unchanged. The exact mechanism of SARS-CoV-2 vaccine-induced AEFI remains unknown, and further studies are required to explore these phenomena.

Population pharmacokinetic and pharmacodynamic analysis of rivaroxaban in Chinese patients with non-valvular atrial fibrillation

Rivaroxaban, a direct factor Xa inhibitor, is widely used for stroke prevention in patients with non-valvular atrial fibrillation (NVAF). The aim of this study was to conduct a population pharmacokinetic-pharmacodynamic (PK-PD) analysis of rivaroxaban in Chinese patients with NVAF to assess ethnic differences and provide model-based precision dosing. A total of 256 rivaroxaban plasma concentrations and 244 prothrombin time (PT) measurements were obtained from 195 Chinese NVAF patients from a prospective clinical trial. The population PK-PD model was developed using nonlinear mixed effects modeling (NONMEM) software. The PK of rivaroxaban was adequately described using a one-compartment model with first-order adsorption and elimination. Estimated glomerular filtration rate (eGFR) was identified as a major covariate for apparent clearance. No single nucleotide polymorphism was identified as a significant covariate. PT exhibited a linear relationship with rivaroxaban concentration. Total bilirubin (TBIL) and eGFR were identified as significant covariates for baseline PT. According to the Monte Carlo simulation, 15 mg for Chinese patients with eGFR ≥50 mL/min and normal liver function yielded an exposure comparable to 20 mg for Caucasian patients. Patients with moderately impaired renal function may require a lower dose of rivaroxaban to avoid overexposure. Moreover, there was an approximate 26% increase in PT levels in patients with TBIL of 34 μmol/L and eGFR of 30 mL/min, which could increase the risk of major bleeding. The established population PK-PD model could inform individualized dosing for Chinese NVAF patients who are administered rivaroxaban.

Rationale and design of a prospective study evaluating population pharmacokinetics and pharmacodynamics of rivaroxaban in Chinese patients with non-valvular atrial fibrillation

INTRODUCTION

Rivaroxaban is one of the most commonly used non-vitamin K antagonists for stroke prevention in patients with non-valvular atrial fibrillation (NVAF). Different individual exposures exist for Asian and non-Asian populations, and dose selection is different for Japanese and non-Japanese subjects. Few studies have investigated the pharmacokinetics (PK) and pharmacodynamics (PD) of rivaroxaban in Chinese patients and provided a solid reference for dose selection and individualised therapy.

METHODS AND ANALYSIS

This is a single-centre prospective study. Rivaroxaban-treated Chinese NVAF patients will be recruited according to predetermined inclusion criteria. Blood samples will be collected from both outpatients and inpatients with different sampling strategies at steady state. Rivaroxaban plasma concentration, factor Xa activity, prothrombin time and single-nucleotide polymorphisms of candidate genes will be evaluated. Follow-up will be conducted following 3 and 6 months after enrolment to collect information about the safety and efficacy outcomes. A nonlinear mixed-effects modelling strategy will be used to develop a population PK-PD model of rivaroxaban.

ETHICS AND DISSEMINATION

The study has been approved by the Ethics Committee of Huashan Hospital, Fudan University (KY2020-016). The study findings will be submitted to peer-reviewed journals and shared with public health authorities.

TRIAL REGISTRATION NUMBER

ChiCTR2100046685.

Association between cyclin-dependent kinase 4/6 inhibitors and venous thromboembolism: analysis of F.A.E.R.S. data

Objectives:Real world studies have started to emerged on occurrence of venous thromboembolism (VTE) with cyclin-dependent kinase 4 and 6 (CDK4/6) inhibitors, but still deserve constant surveillance and evaluation. This study was to analyze this association. Methods: Adverse event cases were acquired from the US Food and Drug Administration Adverse Event Reporting System (FAERS) database betweenJanuary 1st 2015 and December 31st 2020.Signals indicating association between CDK 4/6 inhibitors and VTE were identified by reporting odds ratio (ROR). Results: CDK 4/6 inhibitors had a total of 631 reports of VTE (ROR 1.44, 95% CI 1.33-1.55) compared with non-CDK 4/6 inhibitors. Palbociclib (ROR 1.42, 95% CI 1.09-1.88) demonstratedthe highest number of VTE reports, followed by ribociclib (ROR 1.41, 95% CI 1.29-1.54) and abemaciclib (ROR 0.92, 95% CI 0.72-1.17). Conclusions:Although it is not able to confirm the casual relationship between VTE and CDK4/6 inhibitors, this study suggested signal of VTE reporting in patients receiving CDK4/6 inhibitors, which is likely to reflect a potential association. The results may enhance physicians' awareness of the potential side effect of VTE associated with CDK 4/6 inhibitors. An early recognition of VTE signs/symptoms could decrease the morbidity and severity of such adverse events.

[Analysis of the clinical features and the risk factors of severe adenovirus pneumonia in children]

Objective: To analyze the clinical characteristics, risk factors for critical illness and death of severe adenovirus pneumonia in children, so as to provide clinical evidences for early diagnosis and reliable treatment. Methods: A total of 75 pediatric cases with severe adenovirus pneumonia admitted to Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology from January to October 2019 were studied. The clinical features, laboratory and imaging data, therapeutic approaches, efficacy of the treatments and prognosis were investigated retrospectively. Patients were divided into severe group and critical group. Chi square test and Mann-Whitney U rank sum test were used to analyze the data of the two groups. The risk factors for critical illness and death were analyzed by univariate and multivariate Logistic regression. Results: Among the 75 children, there were 52 males and 23 females, aged from 3 months to 8 years, including 30 of severe cases and 45 of critical case. The positive rate of adenovirus antigen in nasopharyngeal swab was 21% (15/72), and the positive rate of serum adenovirus IgM antibody was only 13% (10/75). However, the positive rate of adenovirus nucleic acid in nasopharyngeal swab was 75% (21/28). What is more, the positive rates of metagenomics next generation sequencing (mNGS) in plasma and bronchoalveolar lavage fluid were 92% (33/36) and 96% (54/56), respectively, of which 95% (63/66) were confirmed as adenovirus type 7. Relatively high dose of ribavirin and integrated therapeutic approaches (respiratory support, glucocorticoids, immunoglobulin and organ supportive therapies) were used. The recovery rate was 77% (58/75), the improvement rate was 8% (6/75) and the mortality rate was 15% (11/75). The proportion of children with the duration of fever longer than 3 days after ribavirin treatment in the critical group was significantly higher than that in the severe group(51% (18/35) vs. 8% (2/26), χ²=12.949, P<0.05). The risk factors for critical illness were younger than 4 years, longer duration of fever before and after admission to PICU, oxygenation index<300 mmHg (1 mm Hg=0.133 kPa), ferritin>1 000 μg/L, lactate dehydrogenase (LDH)>1 500 U/L, 5 lung lobes involvement, pleural effusion and (or) air leakage (all P<0.05). Among them, 5 lung lobes involvement was the independent risk factor for critical illness (adjusted OR=49.641, 95%CI 4.186-588.618, P=0.002). Risk factors for death included longer duration of fever after being admitted to PICU, oxygenation index<100 mmHg, ferritin>2 000 μg/L, interleukin (IL)-6>100 ng/L, LDH>1 500 U/L, pleural effusion and (or) air leakage (all P<0.05). Among them, IL-6>100 ng/L was the independent risk factor for the mortalities of critically ill children (adjusted OR=16.094, 95%CI 2.059-25.787, P=0.008). Conclusions: The mortality rate of severe pediatric adenovirus pneumonia caused by adenovirus type 7 is high. High positive rates of adenovirus nucleic acid in nasopharyngeal swabs and mNGS in plasma or bronchoalveolar lavage fluid contribute to early diagnosis, and mNGS can also be used for serotyping. Younger children under 4 years of age, persistent fever, extensive pulmonary lesions and significantly increased inflammatory cytokines such as IL-6 are warning indicators for critical illness and poor prognosis. Relatively high dose of ribavirin combined with integrated therapeutic approaches are beneficial for prognosis.

Multiple rare causes of post-traumatic elbow stiffness in an adolescent patient: A case report and review of literature

BACKGROUND

Joint stiffness after elbow surgery is not a rare complication, and is always accompanied by deformity. The causes of joint stiffness are multiple in different patients, and divided into intrinsic and extrinsic causes. Herein, we report an unusual case of posttraumatic elbow stiffness due to multiple and rare causes.

CASE SUMMARY

A 19-year-old male was hospitalized with the loss of motion of the left elbow for over ten years. Left limb computed tomography revealed left elbow stiffness with bony block and connection. The patient underwent surgery, and the etiology of joint stiffness was found to be a rare combination of common and uncommon causes. During an 18-mo follow-up period, the patient’s left elbow had normal motion and he was symptom-free.

CONCLUSION

However, this case combined with multiple and rare causes highlights that the patient with scar physique is likely to be accompanied with more severe soft tissue, nerve contracture, and heterotypic ossification, even during recurrence.

Safety assessment of concurrent statin treatment and evaluation of drug interactions in China

Objectives

Acute muscle injury and potentially fatal rhabdomyolysis may occur with the use of statins and certain enzyme inhibitors, but data on this topic from China are quite limited. This study aimed to measure the concomitant exposure of patients to different statins and their enzyme inhibitors or interacting medications in 76 hospitals in six Chinese cities.

Methods

Prescription database was retrieved from Hospital Prescription Analysis Cooperation Project from January 2015 to December 2015, covering 76 tertiary facilities in six cities in China. Every evidence-based enzyme inhibitor was included, and labeled enzyme inhibitors and other relevant information were identified and obtained using the Drug Safety Update from the UK Medicines and Healthcare Products Regulatory Agency. The proportions of different statin types among all patients and those co-medicated with their inhibitors were examined.

Results

A total of 296,765 patients exposed to statins were included in this study. 80% of patients (n = 144,863, 80.5%) were concomitantly prescribed a CYP3A4-metabolized statin with an interacting drug during the study period. Among those prescribed a non-CYP3A4-metabolized statin, 40.0% of patients were concomitantly given an interacting drug, and approximately 20% of patients were concomitantly given a labeled inhibitor, predominantly calcium channel blockers, other statins, and fibrates. Rates of co-prescription were higher in patients aged over 65 years and in patients taking high-dose statins.

Conclusion

Statins were frequently co-prescribed with metabolic inhibitors in China, where drug safety strategy on highlighting warnings and contraindications of statins are still lacking. For high-dose statins patients who are over 65 years and co-administered with any metabolic inhibitors, prescribers and pharmacists should be more concerned in order to prevent adverse drug reactions.

Interplay between unfolded protein response and autophagy promotes tumor drug resistance

The endoplasmic reticulum (ER) is involved in the quality control of secreted protein via promoting the correct folding of nascent protein and mediating the degradation of unfolded or misfolded protein, namely ER-associated degradation. When the unfolded or misfolded proteins are abundant, the unfolded protein response (UPR) is elicited, an adaptive signaling cascade from the ER to the nucleus, which restores the homeostatic functions of the ER. Autophagy is a conserved catabolic process where cellular long-lived proteins and damaged organelles are engulfed and degraded for recycling to maintain homeostasis. The UPR and autophagy occur simultaneously and are involved in pathological processes, including tumorigenesis, chemoresistance of malignancies and neurodegeneration. Accumulative data has indicated that the UPR may induce autophagy and that autophagy is able to alleviate the UPR. However, the detailed mechanism of interplay between autophagy and UPR remains to be fully understood. The present review aimed to depict the core pathways of the two processes and to elucidate how autophagy and UPR are regulated. Moreover, the review also discusses the molecular mechanism of crosstalk between the UPR and autophagy and their roles in malignant survival and drug resistance.

Comments on Bu et al. "P16(INK₄a) overexpression and survival in osteosarcoma patients: a meta analysis"

Recently, we read the article "P16(INK4a) overexpression and survival in osteosarcoma patients: a meta analysis" by Jie Bu and his colleagues, published in the recent issue of International Journal Of Experimental Pathology. This research performed a meta-analysis to uncover the role of P16(INK4a) expression in overall survival rate in patients with osteosarcoma. The investigators concluded as follows: (i) the pateints with overexpression of P16(INK4a) had a longer overall survival rate than that with loss expression of P16(INK4a); (ii) P16(INK4a) was an effective biomarker of prognosis in patients with osteosarcoma.The findings are valubale and encouraging. However, some flaws and imperfections rooted in this work.

Tectorigenin regulates adipogenic differentiation and adipocytokines secretion via PPARγ and IKK/NF-κB signaling

CONTEXT

Obesity is associated with a number of diseases with metabolic abnormalities such as type 2 diabetes (T2D).

OBJECTIVE

We investigate the effects of tectorigenin on 3T3-L1 preadipocyte differentiation and adipocytokines secretion.

MATERIALS AND METHODS

The effects of tectorigenin on adipocyte differentiation were studied using Oil Red O staining. Effects of tectorigenin on adipogenesis-related genes expression and adipocytokines secretion were measured by the real-time quantitative RT-PCR and ELISA method, respectively. Reporter gene assays were performed to determine the PPARγ and NF-κB transactivation. We also used [(3)H]-2-deoxy-d-glucose to study the glucose uptake, and the IKK/NF-κB signaling pathway was assessed by western blot analysis. HFD/STZ rats were used to evaluate the therapeutic efficacies of tectorigenin.

RESULTS

Tectorigenin 10, 25, 50, and 75 μM inhibited 3T3-L1 adipogenesis and related genes transcription. TNF-α-induced changes of IL-6, MCP-1, as well as adiponectin in 3T3-L1 were markedly reversed by tectorigenin at 75 μM. Further investigation using reporter gene revealed that tectorigenin was a partial PPARγ agonist with an IC50 value of 13.3 μM. Tectorigenin improved basal and insulin-stimulated glucose uptake in mature 3T3-L1 adipocytes. Moreover, tectorigenin antagonized TNF-α-induced NF-κB transactivation and p65 nuclear translocation. Although tectorigenin (50 and 100 mg/kg) displayed the ability to promote insulin sensitivity and improve glucose metabolism in HFD/STZ rats, it did not cause significant side effects such as body weight gain, fluid retention, or cardiac hypertrophy.

DISCUSSION AND CONCLUSION

These results suggest that tectorigenin may ameliorate hyperglycemia by blocking preadipocyte differentiation and adipocytokines secretion in which PPARγ and NF-κB signaling pathways were involved.

Enhanced extraction of astragalosides from Radix Astragali by negative pressure cavitation-accelerated enzyme pretreatment

The optimal conditions for extraction of astragalosides III and IV (AGs III and IV) in Radix Astragali by negative pressure cavitation-accelerated enzyme pretreatment were studied on the basis of a Box-Behnken design and response surface methodology. Experimental results showed that negative pressure, amount of enzyme and incubation temperature were the main factors governing the enzyme pretreatment of Radix Astragali. The optimum parameters were obtained as follows: negative pressure -0.08 Mpa, amount of enzyme 1.48% (w/w of materials) and incubation temperature 45 degrees C. Under the optimal conditions, the maximal extraction yields of AGs III and IV were 0.103 and 0.325 mg/g, which were 41.67% and 65.31% increased as compared to those without enzyme pretreatment, respectively. The effect of negative pressure cavitation and enzyme pretreatment on the structural changes of plant cells was observed by scanning electron microscopy. In conclusion, negative pressure cavitation-accelerated enzyme pretreatment was proved to be environment-friendly and economical, and could be used in secondary metabolites production.

[Studies on the constituents from the herba of Erigeron acer]

OBJECTIVE

To investigate the chemical constituents of the aerial part of Erigeron acer.

METHODS

The chemical constituents were isolated by various columns and thin layer chromatographic methods. The structures were identified by spectral data.

RESULTS

Five compounds were isolated and identified as alpha-amyrin (1), beta-amyrin (2), caffeic acid (3), quercetin (4), 4'-hydroxywogonin-7-O-beta-D-glucuronic acid glycoside (5).

CONCLUSION

The five compounds are obtained from this plant for the first time. The signals of 13C-NMR of the compound(5) are reassigned by means of DEPT, HMQC, HMBC, the signals of 1H-NMR of 2" - 5"-H of the glucuronic acid moiety are assigned by means of HMBC, HMQC, 1H-1H COSY for the first time.

Enzyme assisted extraction of luteolin and apigenin from pigeonpea [Cajanuscajan (L.) Millsp.] leaves

Luteolin and apigenin are naturally occurring flavones with a wide spectrum of pharmacological properties. In the present study, enzyme assisted extraction of luteolin and apigenin from pigeonpea leaves using commercial plant cell wall degrading enzyme preparations including cellulase, beta-glucosidase and pectinase were examined. We found that pectinase offered a better performance in enhancement of the extraction yields of luteolin and apigenin than cellulase and beta-glucosidase. The pectinase assisted extraction process was further optimized by varying different parameters such as pectinase concentration, time of incubation, pH of pectinase solution, and incubation temperature. The optimum parameters were obtained as follows: 0.4mg/ml pectinase, incubation for 18h at 30-35°C, pH of pectinase solution 3.5-4. Under the optimum conditions, the extraction yields of luteolin and apigenin achieved 0.268 and 0.132mg/g in pectinase treated sample, which increased 248% and 239%, respectively, compared with the untreated ones.

Preliminary report on the effect of Nd: YAG laser irradiation on canine tooth pulps

OBJECTIVE

To study the effects of Nd: YAG laser irradiation on the canine tooth pulps.

METHODS

The crown pulp of dog was exposed and excised by ND: YAG laser irradiation. Histopathological examination was used to check changes of the tissues in root canal and periodontium.

RESULTS

The pulp of the crown could be successfully excised by Nd: YAG laser without harmful changes in either root canal or periodontal tissues.

CONCLUSION

This study may provide an experimental basis for the clinical possibility of crown pulp excision by using Nd: YAG laser irradiation.

Structure, interaction and electron transfer between cytochrome b5, its E44A and/or E56A mutants and cytochrome c

Site-directed mutagenesis has been used to produce variants of a tryptic fragment of bovine liver cytochrome b5 in which Glu44 and Glu56 are mutated to alanine. The reduction potentials measured by spectroelectrochemical titration (in the presence of 1 mM (Ru(NH3)6)3+, pH 7.0 and I=0.1 M) are 4.5, 6.0, 6.0 and 7.5 mV versus the standard hydrogen electrode (SHE) for the wild-type and E44A, E56A and E44/56A mutants of cytochrome b5, respectively. A comparative two-dimensional NMR study of cytochrome b5 and its E44/56A mutant in water solution has been achieved. Resonance assignments of side-chains have been completed successfully. The NMR results suggest that the secondary structures and global folding of the E44/56A mutant remain unchanged, but the mutation of both Glu44 and Glu56 to hydrophobic alanine may lead to the two helices containing mutated residues contracting towards the heme center. The inner mobility of the Gly42 approximately Glu44 segment in cytochrome b5 may be responsible for the difference of the binding mode between Glu44 and Glu56 with cytochrome c. The binding between cytochrome c and cytochrome b5 was studied by optical difference spectra of cytochrome c and variants of cytochrome b5. The association constants (KA) for the wild-type, E44A, E56A, and E44/56A mutants of cytochrome b5 with cytochrome c, are 4.70(+/-0. 10)x10(6) M-1, 1.88(+/-0.03)x10(6) M-1, 2.70(+/-0.13)x10(6) M-1, and 1.14(+/-0.05)x10(6) M-1, respectively. This is indicative that both Glu44 and Glu56 are involved in the complex formation between cytochrome b5 and cytochrome c. The reduction of horse heart ferricytochrome c by recombinant ferrocytochrome b5 and its mutants has been studied. The rate constant of the electron transfer reaction between ferricytochrome c and wild-type ferrocytochrome b5 (1.074(+/-0.49)x10(7) M-1 s-1) is higher than those of the mutant protein E44A (8.98(+/-0.20)x10(6) M-1 s-1), E56A (8.76(+/-0. 39)x10(6) M-1 s-1), and E44/56A (8.02(+/-0.38)x10(6) M-1 s-1) at 15 degreesC, pH 7.0, I=0.35 M. The rate constants are strongly dependent on ionic strength and temperature. These studies, by means of a series of techniques, provide conclusive results that the interaction between cytochrome b5 and cytochrome c is electrostatically guided, and, more importantly, that both Glu44 and Glu56 participate in the electron transfer reaction.