Comparative efficacy of vancomycin in treating ST5 and ST764 methicillin-resistant Staphylococcus aureus infections in adult patients

IMPORTANCE

Methicillin-resistant Staphylococcus aureus (MRSA) is a bacterium that is resistant to multiple drugs and can cause serious infections. In recent years, one of the most widespread strains of MRSA worldwide has been the clonal complex 5 (CC5) type. Sequence type 5 (ST5) and ST764 are two prevalent CC5 strains. Although ST5 and ST764 are genotypically identical, ST764 is classified as a hybrid variant of ST5 with characteristics of community-associated MRSA (CA-MRSA). In contrast to ST5, ST764 lacks the tst and sec genes but carries the staphylococcal enterotoxin B (seb) gene. Vancomycin is commonly used as the first-line treatment for MRSA infections. However, it is currently unclear whether the genetic differences between the ST5 and ST764 strains have any impact on the efficacy of vancomycin in treating MRSA infections. We conducted a prospective observational study comparing the efficacy of vancomycin against ST5-MRSA and ST764-MRSA in five hospitals in China. There were significant differences in bacteriological efficacy between the two groups, with virulence genes, such as the tst gene, being a risk factor for bacterial persistence (adjusted odds ratio, 4.509; 95% confidence interval, 1.216 to 16.724; P = 0.024). In the future, it may be necessary to consider personalized vancomycin treatment strategies based on the genetic characteristics of MRSA isolates.

Heterozygous CARD9 mutation favors the development of allergic bronchopulmonary aspergillosis

BACKGROUND

Previous research demonstrated that a homozygous mutation of g.136372044G>A (S12N) in caspase recruitment domain family member 9 ( CARD9 ) is critical for producing Aspergillus fumigatus -induced ( Af -induced) T helper 2 (T H 2)-mediated responses in allergic bronchopulmonary aspergillosis (ABPA). However, it remains unclear whether the CARD9S12N mutation, especially the heterozygous occurrence, predisposes the host to ABPA.

METHODS

A total of 61 ABPA patients and 264 controls (including 156 healthy controls and 108 asthma patients) were recruited for sequencing the CARD9 locus to clarify whether patients with this heterozygous single-nucleotide polymorphisms are predisposed to the development of ABPA. A series of in vivo and in vitro experiments, such as quantitative real-time polymerase chain reaction, flow cytometry, and RNA isolation and quantification, were used to illuminate the involved mechanism of the disease.

RESULTS

The presence of the p.S12N mutation was associated with a significant risk of ABPA in ABPA patients when compared with healthy controls and asthma patients, regardless of Aspergillus sensitivity. Relative to healthy controls without relevant allergies, the mutation of p.S12N was associated with a significant risk of ABPA (OR: 2.69 and 4.17 for GA and AA genotypes, P = 0.003 and 0.029, respectively). Compared with patients with asthma, ABPA patients had a significantly higher heterozygous mutation (GA genotype), indicating that p.S12N might be a significant ABPA-susceptibility locus ( aspergillus sensitized asthma: OR: 3.02, P = 0.009; aspergillus unsensitized asthma: OR: 2.94, P = 0.005). The mutant allele was preferentially expressed in ABPA patients with heterozygous CARD9S12N , which contributes to its functional alterations to facilitate Af -induced T H 2-mediated ABPA development. In terms of mechanism, Card9 wild-type ( Card9WT ) expression levels decreased significantly due to Af -induced decay of its messenger RNA compared to the heterozygous Card9S12N . In addition, ABPA patients with heterozygous CARD9S12N had increased Af -induced interleukin-5 production.

CONCLUSION

Our study provides the genetic evidence showing that the heterozygous mutation of CARD9S12N , followed by allele expression imbalance of CARD9S12N , facilitates the development of ABPA.

The role of long-acting muscarinic antagonist/long-acting β agonist fixed-dose combination treatment for chronic obstructive pulmonary disease in China: a narrative review

Objective

To provide an overview of the existing international and Chinese evidence regarding dual bronchodilator inhalation therapy and to make recommendations for the further improvement of chronic obstructive pulmonary disease (COPD) management in clinical practice in China.

Background

COPD is a progressive lung disease that is characterized by persistent airflow limitation and is a major contributor to the disease burden in China. Symptoms in Chinese patients are relatively more severe. Currently, many Chinese COPD patients are undertreated. Dual bronchodilator therapy consisting of a long-acting muscarinic antagonist (LAMA) and a long-acting β agonist (LABA) is considered a good choice for COPD patients due to the increased bronchodilation without an increase in adverse events; these combinations can fill in the gap in currently available COPD treatments and provide new pharmacotherapy options for Chinese patients. LAMA/LABA fixed-dose combinations (FDCs) have become more important in clinical practice and guidelines in China regarding their therapeutic effects and safety.

Methods

Clinical trials on LAMA/LABA in COPD were retrieved in ClinicalTrials.gov, while important COPD guidelines published in English or Chinese were found in PubMed and Wanfang Database.

Conclusions

We recommend the adoption of a clinical pathway in China that includes an assessment and management algorithm that considers the clinical characteristics in China and classifies the phenotypic characteristics of COPD according to a suitable system. Based on the current information, we can conclude that LAMA/LABA FDCs are a suitable and economically viable choice to reduce symptoms and improve the quality of life (QoL) of patients.

Short-acting beta-2 agonist prescription patterns and clinical outcomes in Chinese patients with asthma: an observational study in mainland China for the SABINA programme

Objectives:

The SABINA CHINA study aimed to determine prescription data for asthma medication with a focus on SABA and ICS in a representative population of patients with asthma in China.

Methods:

SABINA China was a multicentre, observational, cross-sectional study with data collected retrospectively from a convenience sample of 25 tertiary centres across China. Patients (age ⩾ 12 years) with ⩾3 consultations/year were enrolled. Data were collected on clinical characteristics, asthma severity, and symptom control (as per GINA 2017), treatment and history of severe exacerbations over the past year. SABA over-prescription was defined as ⩾3 SABA canisters/year. Descriptive statistics are presented.

Results:

Between March and August 2020, 498 patients were included in the outcome analysis. Mean (SD) age was 48.7 (15.0) years, 57.9% were female and 91% had moderate-to-severe asthma (n = 453). Overall, 12.5% (n = 62) and 26.4% (n = 131) of patients had uncontrolled and partly controlled asthma, respectively. SABA add-on was prescribed to 20.3% (n = 101) of patients; one patient with moderate-to-severe asthma was prescribed SABA-alone. SABA over-prescription in the overall population was 4.0% (n = 20; all with moderate-to-severe asthma) and 19.8% (20/101) among those prescribed SABA add-on. In the mild asthma group, 50% (n = 22) were prescribed ICS/LABA and 43.2% (n = 19) were prescribed LTRA. Among those with moderate-to-severe asthma, 97.4% (n = 441) were prescribed ICS/LABA and 55.0% (n = 249) were prescribed LTRA. Approximately 30% of patients (n = 149) experienced ⩾1% and 6.6% (n = 33) ⩾3 severe exacerbations in the preceding year; mean annual number of severe exacerbation/patient was 0.6 (1.2). Among those prescribed SABA add-on, ICS/LABA and LTRA (non-mutually exclusive groups due to overlapping prescriptions), 54.5%, 29.9%, and 35.3% had ⩾1 severe exacerbations, respectively.

Conclusion:

Among patients with predominantly moderate-to-severe asthma managed in tertiary care and were prescribed SABA, 1 in 5 received ⩾3 canisters/year. Fewer patients who received ICS/LABA prescriptions experienced annual exacerbations than those prescribed SABA add-on.

Distribution of COPD Comorbidities and Creation of Acute Exacerbation Risk Score: Results from SCICP

Background

Chronic obstructive pulmonary disease (COPD) often coexists with multiple comorbidities which may have a significant impact on acute exacerbations of patients. At present, what kind of comorbidities affects acute exacerbations and how comorbidities lead to poor prognosis are still controversial. The purpose of our study is to determine the impact of comorbidities on COPD exacerbation and establish an acute exacerbation risk assessment system related to comorbidities.

Methods

A total of 742 COPD patients participated in the Shanghai COPD Investigation on Comorbidity Program (SCICP, ChiCTR2000030911). Finally, the baseline information of 415 participants and one-year follow-up data were involved in the analysis. We collected hemogram indices, pulmonary function tests and acute exacerbation of COPD with regular medical follow-up. Q-type cluster analysis was used to determine the clusters of participants. Receiver operating characteristic (ROC) analysis was constructed to assess the ability of indicators in predicting acute exacerbations.

Results

Almost 65% of the population we investigated had at least one comorbidity. The distribution and incidence of comorbidities differed between exacerbation group and non-exacerbation group. Three comorbidity clusters were identified: (1) respiratory, metabolic, immune and psychologic disease (non-severe cases); (2) cardiovascular and neoplastic disease (severe cases); (3) less comorbidity. Different sub-phenotypes of COPD patients showed significant distinction in health status. Anxiety (OR=5.936, P=0.001), angina (OR=10.155, P=0.025) and hypertension (OR=3.142, P=0.001) were found to be independent risk factors of exacerbation in a year. The novel risk score containing BODEx and four diseases showed great prognostic value of COPD exacerbation in developing sample.

Conclusion

Our study detailed the major interaction between comorbidities and exacerbation in COPD. Noteworthily, a novel risk score using comprehensive index – BODEx – and comorbidity parameters can identify patients at high risk of acute exacerbation.

Comparative analysis of effectiveness of asthma control test-guided treatment versus usual care in patients with asthma from China

OBJECTIVE

The present study compared the effectiveness of asthma control test (ACT)-guided treatment vs. usual care (UC) in patients with asthma from China.

METHODS

This prospective, phase IV, multicenter, cluster-randomized, open-label 24-week study was conducted in China; patients were randomized to either ACT-guided treatment or UC group. The patients recorded peak expiratory flow, symptoms, and medication in a diary card every day and completed ACT at every clinic visit. For the UC group, patients completed ACT after the physician's treatment decision.

RESULTS

In total, 83.6% patients (n = 443/530; ACT: n = 209, UC: n = 234) completed the study. A significantly higher proportion of patients (adjusted OR [95% CI]: 7.87 (1.29, 48.11; p = 0.027) responded to the treatment and had ACT total score ≥20 or demonstrated an improvement of >3 points in ACT total score in ≥1 post-baseline assessment in the ACT-guided treatment vs. UC group. A higher proportion of patients had an ACT total score ≥20 and an improvement of >3 points in ACT total score at Week 24 in the ACT-guided treatment vs. the UC group (adjusted OR (95% CI):2.28 (1.07, 4.85; p = 0.036). A significant difference (p = 0.005) in change from baseline in ACT total score was observed in ACT-guided treatment vs. UC group at Week 24. The mean annual exacerbation rate was similar in both the groups.

CONCLUSIONS

ACT-guided treatment was more effective in achieving ACT total score ≥20 or showing an improvement of >3 points in the ACT total score and well tolerated compared with UC treatment in the 24-week treatment period.

TRIAL REGISTRATION

Clinical trials.gov Identifier: NCT02868281, https://clinicaltrials.gov/; GlaxoSmithKline study ID: 201097, https://www.gsk-studyregister.com/.

The Combination of Hemogram Indexes to Predict Exacerbation in Stable Chronic Obstructive Pulmonary Disease

Background: Chronic obstructive pulmonary disease (COPD) is characterized by pulmonary and systemic inflammatory processes, and exacerbation of COPD represents a critical moment in the progression of COPD. Several biomarkers of inflammation have been proposed to have a predictive function in acute exacerbation. However, their use is still limited in routine clinical practice. The purpose of our study is to explore the prognostic efficacy of novel inflammatory hemogram indexes in the exacerbation among stable COPD patients. Method: A total of 275 stable COPD patients from the Shanghai COPD Investigation Comorbidity Program were analyzed in our study. Blood examinations, especially ratio indexes like platelet-lymphocyte ratio (PLR), platelet × neutrophil/lymphocyte ratio [systemic immune-inflammation index (SII)], and monocyte × neutrophil/lymphocyte ratio [systemic inflammation response index (SIRI)], lung function test, CT scans, and questionnaires were performed at baseline and routine follow-ups. Clinical characteristics and information of exacerbations were collected every 6 months. The relationship between hemogram indexes and diverse degrees of exacerbation was assessed by logistic regression. The receiver operating characteristic (ROC) curve and area under the curve (AUC) were used to evaluate the ability of hemogram indexes to predict exacerbation of COPD. Furthermore, the discrimination and accuracy of combined indexes were measured by ROC and calibration curve. Result: There was a significant positive correlation between PLR levels and total exacerbation of COPD patients in a stable stage in a year. Also, the predictive ability of PLR exceeded any other ratio indexes, with an AUC of 0.66. SII and SIRI ranked second only to PLR, with an AUC of 0.64. When combining PLR with other indexes (sex, COPD year, and St. George's Respiratory Questionnaire scores), they were considered as the most suitable panel of index to predict total exacerbation. Based on the result of the ROC curve and calibration curve, the combination shows optimal discrimination and accuracy to predict exacerbation events in COPD patients. Conclusion: The hemogram indexes PLR, SII, and SIRI were associated with COPD exacerbation. Moreover, the prediction capacity of exacerbation was significantly elevated after combining inflammatory hemogram index PLR with other indexes, which will make it a promisingly simple and effective marker to predict exacerbation in patients with stable COPD.

Model-based Evaluation of the Clinical and Microbiological Efficacy of Vancomycin: A Prospective Study of Chinese Adult In-house Patients

Background

Our aims in this prospective study were to evaluate the correlations between pharmacokinetic/pharmacodynamic (PK/PD) indices and the clinical/microbiological efficacy of vancomycin and to identify an appropriate PK/PD target in the Chinese population to guide vancomycin treatment in the clinic.

Methods

Adult patients from 11 hospitals in China with gram-positive infections who received vancomycin therapy for ≥5 days and who were under therapeutic drug monitoring (TDM) were enrolled in this study. A 1-compartment population PK model was established and validated. The correlations between PK/PD indices (Cmin, Cmax, 0-24 hour area under the curve (AUC0-24), and AUC0-24/minimum inhibitory concentration (MIC) and clinical outcomes (clinical efficacy and bacterial eradication) were evaluated.

Results

In total, 402 adult Chinese patients were enrolled. Among them, 380 patients were evaluable for PK analysis, and 334 were evaluable for PK/PD analysis. In the final population PK model, creatinine clearance (CLCR) was the significant covariate on CL (typical value, 3.87 L/hour; between-subject variability (BSV), 12.5%), and age was the significant covariate on volume of distribution (V) (typical value, 45.1 L; BSV, 24.8%). The univariate analysis showed that Cmax, AUC0-24, and AUC0-24/MIC were significantly different or marginally significantly different (P values were 0.009, 0.0385, and 0.0509, respectively) between microbiological outcome groups with coagulase-negative Staphylococcus infections. However, there were no significant differences (P > .05) in the above PK parameters by multivariate logistic regression analysis, indicating there was no independently associated factor.

Conclusions

No significant correlations were identified between PK/PD indices and the clinical or microbiological efficacy of vancomycin in Chinese patients. The necessity of vancomycin TDM based on trough concentration and the current treatment target of AUC0-24/MIC ≥400 need to be further evaluated and confirmed in additional prospective studies.

Initial experience of robot-assisted Ivor-Lewis esophagectomy: 61 consecutive cases from a single Chinese institution

This study aims to report the technical details and preliminary outcomes of robot-assisted Ivor-Lewis esophagectomy (RAILE) using two different types of intrathoracic anastomosis from a single institution in China. From May 2015 to October 2017, 61 patients diagnosed with mid-lower esophageal cancer were treated with RAILE. The RAILE procedure was performed in two stages. The first 35 patients underwent circular end-to-end stapled intrathoracic anastomosis (stapled group), and the remaining 26 patients had a double-layered, completely hand-sewn intrathoracic anastomosis (hand-sewn group). Patient characteristics, surgical techniques, postoperative complications, and pathology outcomes were analyzed. The mean operating time and mean blood loss were 315.6 ± 59.4 minutes and 189.3 ± 95.8 mL, respectively. There was one patient who underwent conversion to thoracotomy. The 30-day and in-hospital mortality rates were 0%. Overall complications were observed in 22 patients (36.1%) according to the Clavien-Dindo (CD) and the Esophagectomy Complications Consensus Group (ECCG) classifications, of whom 6 patients (9.8%) had anastomotic leakage (ECCG, Type II). The median length of hospitalization (LOH) was 10 days (IQR, 5 days). Complete (R0) resection was achieved in all cases. The mean tumor size was 3.2 ± 1.5 cm, and the mean number of totally dissected lymph nodes was 19.3 ± 9.2. Regarding the operative outcomes between stapled and hand-sewn groups, there were no significant differences in the operative time (325.4 ± 66.6 vs. 302.3 ± 45.9 min, P = 0.114), blood loss (172.9 ± 74.1 vs. 211.5 ± 117.0 mL, P = 0.147), conversion rate (2.9 vs. 0%, P = 1.000), overall complication rate (37.1 vs. 34.6%, P = 0.839) or LOH (10 vs. 9.5 days, P = 0.415). RAILE using both stapled and hand-sewn intrathoracic anastomosis is safe and technically feasible with satisfactory perioperative outcomes for the treatment of mid-lower thoracic esophageal cancer.

Efficacy of sequential three-step empirical therapy for chronic cough

Background:

Empirical three-step therapy has been proved in just one hospital. This study aimed to demonstrate applicability of the sequential empirical three-step therapy for chronic cough in different clinical settings.

Methods:

Sequential empirical three-step therapy was given to patients with chronic cough in one tertiary and three secondary care respiratory clinics. Recruiters were initially treated with methoxyphenamine compound as the first-step therapy, followed by corticosteroids as the second-step therapy and the combination of a proton-pump inhibitor and a prokinetic agent as the third-step therapy. The efficacy of the therapy was verified according to the changes in cough symptom score between pre- and post-treatment, and compared among the different clinics.

Results:

In total 155 patients in one tertiary clinic and 193 patients in secondary care clinics were recruited. The total dropout ratio is significantly higher in the secondary care clinics than that in the tertiary clinic (9.3% versus 3.2%, p = 0.023). The therapeutic success rate for cough was 38.7% at first-step therapy, 32.3% at second-step therapy and 20.0% at third-step therapy in the tertiary clinic, and comparable to corresponding 49.7%, 31.1% and 4.1% in secondary care clinics. Furthermore, the overall cough resolution rate was not significantly different (91.0% versus 85.0%, p = 0.091). However, the efficacy of the third-step therapy is much higher (20.0% versus 4.1%, p = 0.001) in the tertiary clinic than in the secondary care clinics.

Conclusions:

Sequential empirical three-step therapy is universally efficacious and useful for management of chronic cough in different clinical settings.

Efficacy of add-on montelukast in nonasthmatic eosinophilic bronchitis: the additive effect on airway inflammation, cough and life quality

Background:

The efficacy of montelukast (MONT), a cysteinyl leukotriene receptor antagonist, in nonasthmatic eosinophilic bronchitis (NAEB), especially its influence on cough associated life quality is still indefinite. We evaluated the efficacy of MONT combined with budesonide (BUD) as compared to BUD monotherapy in improving life quality, suppressing airway eosinophilia and cough remission in NAEB.

Methods:

A prospective, open-labeled, multicenter, randomized controlled trial was conducted. Patients with NAEB (aged 18-75 years) were randomized to inhaled BUD (200 μg, bid) or BUD plus oral MONT (10 μg, qn) for 4 weeks. Leicester cough questionnaire (LCQ) life quality scores, cough visual analog scale (CVAS) scores, eosinophil differential ratio (Eos), and eosinophil cationic protein (ECP) in induced sputum were monitored and compared.

Results:

The control and MONT groups contained 33 and 32 patients, respectively, with similar baseline characteristics. Significant with-in group improvement in CVAS, LCQ scores, Eos, and ECP was observed in both groups during treatment. After 2-week treatment, add-on treatment of MONT was significantly more effective than BUD monotherapy for CVAS decrease and LCQ scores improvement (both P < 0.05). Similar results were seen at 4-week assessment (both P < 0.05). 4-week add-on therapy of MONT also resulted in a higher percentage of patients with normal sputum Eos (<2.5%) and greater decrease of ECP (both P < 0.05).

Conclusions:

MONT combined with BUD was demonstrated cooperative effects in improvement of life quality, suppression of eosinophilic inflammation, and cough remission in patients with NAEB.

The changing epidemiology of asthma in Shanghai, China

OBJECTIVE

To investigate the prevalence of bronchial asthma in Putuo district in Shanghai, China.

METHODS

Cross-sectional, community-based study was performed with random sampling of a district with a population of one million. The subjects were residents of the district and six or more years of age. Questionnaire and spirometry were completed in all subjects. Asthma was defined as physician-diagnosed asthma. The results were compared with the asthma study of 40,000 population completed by the same team in Pudong area of Shanghai in 1997.

RESULTS

We surveyed 27,042 participants. The prevalence of asthma was 1.8% (488/27,042), much higher than the 0.41% (163/40,000) found in the 1997 survey in Pudong area of Shanghai. In subjects with asthma, current smoking, obesity, gender distribution and the combination of allergic diseases between the two studies had no differences. The most prominent causes of asthma exacerbation were cold air, respiratory infection and dust inhalation. Pulmonary function for 428 asthma patients in Putuo survey was analyzed: 228 (53.3%) patients had FEV1%pred lower than 80%. Asthmatics older than 65 years had lower FEV1%pred than other age groups (p < 0.01).

CONCLUSIONS

The prevalence of physician-diagnosed asthma in urban of Shanghai has increased in recent years. The most important causes of asthma exacerbations were cold air, respiratory infection and dust exposure. The proportion of individuals with decreased percent predicted forced expiratory volume of first second increased with age. Strengthening the prevention and treatment of asthma, especially in children with asthma, may decrease the health burden of asthma in the urban Chinese population.

Application of flexible bronchoscopy in inhalation lung injury

Background

As acute inhalational injury is an uncommon presentation to most institutions, a standard approach to its assessment and management, especially using flexible bronchoscopy, has not received significant attention.

Methods

The objective of this study is to evaluate the value of using flexible bronchoscopy as part of the evaluation and management of patients with inhalational lung injury. Twenty-three cases of inhalational lung injury were treated in our three hospitals after a fire in a residential building. The twenty cases that underwent bronchoscopy as part of their management are included in this analysis. After admission, the first bronchoscopy was conducted within 18-72 hours post inhalational injury. G2-level patients were reexamined 24 hours after the first bronchoscopy, while G1-level patients were reexamined 72 hours later. Subsequently, all patients were re-examined every 2-3 days until recovered or until only tunica mucosa bronchi congestion was identified by bronchoscopy.

Results

Twenty patients had airway injury diagnosed by bronchoscopy including burns to the larynx and glottis or large airways. Bronchoscopic classification of the inhalation injury was performed, identifying 12 cases of grade G1 changes and 8 cases of grade G2. The airway injury in the 12 cases of grade G1 patients demonstrated recovery in 2-8 days, in the airway injury of the 8 cases of grade G2 patients had a prolonged recovery with airway injury improving in 6-21 days averaged. The difference in recovery time between the two groups was significant (P <0.05).

Conclusions

The use of flexible bronchoscopy has great value in the diagnosis of inhalational injury without any complications. Its use should be incorporated into clinical practice.

Virtual slides

The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1476676925108926

Regulation network analysis in the esophageal squamous cell carcinoma

BACKGROUND

The incidence of esophageal squamous cell carcinoma (ESCC) has high regional selectivity. The molecular mechanisms of ESCC are complex and involve multiple oncogenes, tumor suppressor genes, receptor tyrosine kinases, cytoplasmic enzymes, and tumor interstitial elements.

AIM

Here we used bioinformatics to obtain some important genes and pathways involved in ESCC.

MATERIALS AND METHODS

In this article, we did Affymetrix microarray data collection from three big databases, and then selected all the differentially expressed genes (DEGs) according to some principles. On this basis, we carried out regulation network analysis and pathway enrichment analysis, obtaining ESCC related regulation network analysis, after which we selected significant pathways on regulation network and established TF-pathway regulation network.

RESULTS

In the transcription factors (TFs) regulation network we found SP1, E2F1, USF2 and SP3 form a local network which suggested that these TFs might play a more important role in ESCC. Some key pathways were also identified, such as P53 signaling pathway, melanoma and prostate cancer pathways.

CONCLUSIONS

The identification of crucial molecular pathways involved in ESCC would ultimately improve therapeutic effects and facilitate the development of new treatment strategies.

Increased expression of paxillin is found in human oesophageal squamous cell carcinoma: a tissue microarray study

Oesophageal cancer is one of the most common cancers worldwide. Currently, the tumour, node, metastasis (TNM) staging system is the primary method for determining its extent and prognosis, however, data suggest this system does not predict prognosis accurately. Research has, therefore, concentrated on searching for specific biomarkers. Paxillin has been shown to play an important role in controlling cell spread and migration. Its over-expression is considered to correlate with the prognosis of some types of cancers, however, the relationship between paxillin expression and clinical outcome in oesophageal cancer has not been investigated. This study determined the expression of paxillin by immunohistochemistry on the tissue microarray of 100 oesophageal squamous cell cancer patients followed up for a mean of 55 months. Paxillin was over-expressed in tumours in 27/100 cases, compared with 6/100 cases for adjacent non-tumoural cells. No correlation occurred between expression of paxillin and overall patient survival, hence paxillin is not an effective prognostic marker in these patients.

TNF polymorphisms modify endotoxin exposure-associated longitudinal lung function decline

OBJECTIVES

Endotoxin exposure induces airway inflammation, hyper-responsiveness and higher expression of tumour necrosis factor (TNF). This study was conducted to investigate whether TNF polymorphisms modify the effect of endotoxin exposure on chronic declines in lung function.

METHODS

Associations between TNF and LTA polymorphisms, endotoxin exposure and lung function were analysed in 263 cotton workers and 230 silk workers as a reference group, who were prospectively followed for 20 years. Multiple linear regression models were used to assess the association, with adjustment for smoking and other covariates.

RESULTS

Endotoxin exposure was associated with faster lung function decline among genotypes associated with higher TNF expression levels, with estimates of annual FEV1 change in relation to endotoxin exposure of -2.9 ml and -6.8 ml in the G/G and G/A+AA genotypes, respectively, for the TNF polymorphism; and -2.0 ml, -4.0 ml and -3.6 ml in A/A, A/G and G/G genotypes, respectively, for the LTA polymorphism. When joint effects of endotoxin exposure and smoking were considered, the effect modification of TNF and LTA polymorphisms was prominent in never smokers.

CONCLUSIONS

TNF and LTA polymorphisms may modify the association between occupational endotoxin exposure and longitudinal lung function decline, which was more clearly observed in never smokers.

Cancer mortality among textile workers in Shanghai, China: a preliminary study

OBJECTIVE

We assessed the association between cotton textile work and cancer mortality.

METHODS

The cancer mortality experience of 912 (444 cotton, 468 silk) textile workers in Shanghai, China, was compared. Workers were followed from 1981 to 2003. The associations between cotton textile work and death due to all cancers combined (with and without lung cancer) and to gastrointestinal cancers were estimated with Cox models, adjusting for age, work years, and pack-years.

RESULTS

There were 69 deaths. The adjusted hazard rate ratio (HR) was 2.10 (95% confidence interval [CI], 0.98-4.47) for all cancers combined and 2.56 (95% CI, 1.14-5.74) after excluding lung cancer. For gastrointestinal cancers, the adjusted HR was 2.09 (95% CI, 0.83-5.27).

CONCLUSIONS

These preliminary data suggest that, with the exception of lung cancer, cotton workers have significantly higher cancer mortality rates than silk workers.

Cloning of novel laccase isozyme genes from Trametes sp. AH28-2 and analyses of their differential expression

Three novel laccase isozyme genes, lacA, lacB, and lacC, have been identified from basidiomycete Trametes sp. AH28-2. These genes display a high similarity with other basidiomycete laccases at the amino acid level. An inferred TATA box and several putative CAAT, MRE, XRE, and CreA consensus sequences were identified in the lacA, lacB, and lacC promoter regions. Different from the TATA boxes of lacA and lacB at about -100, the TATA box of lacC is located at -172. For all the isozymes, copper ion is essential for laccase synthesis in Trametes sp. AH28-2. More interestingly, different aromatic compounds can selectively induce the production of distinct laccase isozymes, with o-toluidine inducing the expression of laccase A (LacA) while 3,5-dihydroxytoluene mainly stimulating the production of laccase B (LacB). Quantitative reverse transcriptase-polymerase chain reaction showed that the accumulation of laccase messenger RNA transcripts is accompanied by the increase of corresponding enzyme activity in cultures. The glucose-repression effect on laccase expression in Trametes sp. AH28-2 was also observed. Furthermore, lower Cu2+ concentration (lower than 0.5 mM) can induce LacA and a novel laccase (LacC), and the latter will disappear when Cu2+ concentration is increased up to 1-2 mM. Upon induction by 3,5-dihydroxytoluene, the ratio of LacA to LacB decreased in the later phase of induction.

TLR4 Asp299Gly and Thr399Ile polymorphisms are very rare in the Chinese population

Endotoxin is an important component of bio-aerosols that contribute to airway inflammation and airflow obstruction. Toll-like receptor 4 (TLR4) mediates the host response to bacterial lipopolysaccharide (LPS), and the Asp299Gly and Thr399Ile polymorphisms have been associated with the development of respiratory diseases. We hypothesized that TLR4 polymorphisms may be associated with a decline of lung function in cotton workers who were exposed continuously to endotoxin. We investigated these two polymorphisms in our 20-year longitudinal cohort of Han Chinese cotton and silk textile workers. The two polymorphisms were genotyped using TaqMan and PCR-restriction fragment length polymorphism methods. No homozygous or heterozygous variant genotypes of the Asp299Gly and Thr339Ile polymorphisms were detected in 491 samples of this population. Our results suggest that the TLR4 Asp299Gly and Thr339Ile polymorphisms are very rare in the Chinese population.

Microsomal Epoxide Hydrolase, Endotoxin, and Lung Function Decline in Cotton Textile Workers

Occupational exposure to endotoxin in organic dust may induce lung function decline. Microsomal epoxide hydrolase (mEH) detoxifies reactive oxygen species generated by endotoxin exposure, and polymorphisms of the mEH gene are associated with altered enzyme activity. We investigated the associations between mEH polymorphisms, endotoxin exposure, and lung function decline in a 20-year prospective study of 265 workers exposed to endotoxin and 234 control subjects. mEH Tyr113His and His139Arg polymorphisms were genotyped by the 5' nuclease assay, and data were analyzed using multivariate linear regression models, adjusting for important covariates. Overall, the annual decline rate of FEV1 was 29.47 ml during the 20-year follow-up. Endotoxin exposure was associated with faster lung function decline among genotypes associated with slower enzyme activity: estimates (SE) of annual FEV1 decline rates for endotoxin exposure were -2.33 (2.07), -2.81 (1.66), and -6.73 (2.83) ml for Tyr/Tyr, Tyr/His, and His/His genotype groups, respectively, for the Tyr113His polymorphism; and -1.82 (2.58) and -4.27 (1.33) ml for Arg/Arg + His/Arg and His/His genotypes, respectively, for the His139Arg polymorphism. We conclude that mEH polymorphisms modify the association between occupational endotoxin exposure and longitudinal lung function decline.

Selective induction, purification and characterization of a laccase isozyme from the basidiomycete Trametes sp. AH28-2

The white-rot fungus Trametes sp. AH28-2 can synthesize extracellular laccase by induction in cellobiose-based liquid culture medium. Both yields and composition of laccase isozymes, produced by Trametes sp. AH28-2, would be quite different with induction by different small-molecule aromatic compounds, o-toluidine, guaiacol and 3,5-dihydroxytoluene, which affected microbial growth and the synthesis of laccase isozymes differentially. Higher concentrations of the three inducers could considerably increase laccase isozymes yields but not change the laccase composition. Coculturing of Trametes sp. AH28-2 with either Aspergillus oryzae or Gloeophyllum trabeum showed a few effects on laccase production. Laccase isozyme, laccase B, was selectively induced by 3,5-dihydroxytoluene and purified to homogeneity by two-step chromatography. Purified laccase B appeared as blue, with a broad peak at about 600 nm and a shoulder peak at about 330 nm. The ratio of absorbance at 280 nm to that at 600 nm was 21. Every molecule of laccase B had approximately four copper atoms. Molecular mass of laccase B was estimated to be 74 kDa on SDS-PAGE, 72 kDa by FPLC and was determined to be 71 454 Da by mass spectrum. After being treated with N-glycosidase F, laccase B lost 25% of its molecular mass. The isoelectric point of laccase B was 4.0. Its optimal pH and temperature for oxidizing guaiacol were respectively 4.7 and 45 C. The half-life of the enzyme at 60 C was 14.0 min. The enzyme showed a good stability in a range of pH value of 3.5-7.5. The K(m) values of the enzyme toward substrates syringaldazine, guaiacol, ABTS, and DMOP were respectively 28.0, 1249.0, 177.0 and 109.8 μM. The corresponding V(max) are 504.0, 1910.0, 117.4 and 159.0 μM min(-1) mg(-1). In addition, activity of laccase B was inhibited strongly by sodium azide and cyanide, mildly by SDS and trifluoroacetic acid, but only weakly by dimethyl sulfoxide.

Tissue-specific expression and gabapentin-binding properties of calcium channel alpha2delta subunit subtypes

We report here the tissue-specific expression and gabapentin-binding properties of calcium channel alpha2delta subunits. Northern blot analysis demonstrated that human alpha2delta-1, -2, and -3 mRNA all had high levels of expression in brain, heart and skeletal muscle. However, the highest expression of human alpha2delta-2 mRNA was found in lung. Human alpha2delta-1, -2, and -3 mRNAs were detected in all portions of brain tested. Western blotting revealed that alpha2delta-2 protein was predominantly expressed in cerebellar cortex (brain) and undetectable in lung. The dissociation between mRNA and protein levels of human alpha2delta-2 in lung suggests possible post-transcriptional regulation. Although mouse alpha2delta-1 proteins exhibited a similar tissue distribution profile as that of human, tissue distribution of mouse alpha2delta-2 and -3 mRNA revealed a different profile. Mouse alpha2delta-3 mRNA was restricted to brain and mouse alpha2delta-2 mRNA was not detectable in lung. Gel electrophoresis under a reduced condition resulted in a mobility shift of both alpha2delta-1 and alpha2delta-2 proteins, suggesting that alpha2 and delta of alpha2delta-2 protein are linked by disulfide bond as are alpha2 and delta of alpha2delta-1. Scatchard plots revealed a single population of gabapentin binding sites for human alpha2delta-2 with the KD value twofold higher than that of porcine alpha2delta-1 (156 +/- 25 nm vs. 72 +/- 9 nm). Inhibition of gabapentin binding to alpha2delta-2 by selected amino acids and gabapentin analogs produced a binding profile similar, but not identical to that of alpha2delta-1.

[Factors of laccase producing and fermentation conditions by a new white-rot fungus AH28-2]

White-rot fungus AH28-2, a newly isolated strain, produced effectively laccase by induction when grown on a synthetic medium. Aromatic compounds of low molecular weight had an inducing influence on laccase production and its isoenzyme compositions. The using of o-toluidine or syringic acid had the best inducing effect. Cu2+ concentration in medium had distinguished effect on laccase production. Enzyme activity was notably increased by Cu2+ and reached the maximum when Cu2+ final concentration was 5 mumol/L. Mn2+ inhibited the synthesis of laccase. Carbon and nitrogen limitation were not beneficial to laccase synthesis, while high nutrient organic medium was beneficial to the growth of cell and the synthesis of laccase. Using cellobiose as the sole carbon source, the highest level enzyme activity reached 82,923. 7 u/L under the condition of optimum fermentation with ABTS as substrate. This enzyme activity was 2.9-fold higher compared to the reported data on international references in recent years.

Ligand binding and structural properties of segments of GABAA receptor alpha 1 subunit overexpressed in Escherichia coli

The gamma-aminobutyric acid, type A (GABA(A)), receptor is the target for numerous therapeutic compounds. In the present study, the Gln(28)-Leu(296), Gln(28)-Arg(276), Gln(28)-Arg(248), and Gln(28)-Glu(165) (numbering of bovine precursor protein) segments of its alpha(1) subunit were overexpressed in Escherichia coli, along with Cys(166)-Leu(296) produced previously, for structural analysis by circular dichroism and ligand binding studies by fluorescence spectroscopy. Results showed that the protein segments were rich in beta-sheet structures. Binding of the fluorescent benzodiazepine Bodipy-FL Ro-1986 was evident from fluorescence resonance energy transfer and fluorescence anisotropy measurements. The binding affinity was in the micromolar range. The binding was attributable more to Cys(166)-Leu(296) than to Gln(28)-Glu(165) and was inhibited by known central benzodiazepine site ligands. Three point mutations, Y187A, T234A, and Y237A, were found to perturb protein secondary structures. Studies with the single Trp mutants W198Y and W273Y indicated that Trp(273) was closer to the binding site than Trp(198).

[Community characteristics of rare trees at Dalaoling of Three-Gorge reservoir area in western Hubei Province]

The quantitative characteristics, plant frequency in layers and species diversity of David involucrata var. vilnoriniara, Euptlea pleiosperma, Stewartia sinensis and Pterostyrax psilophtila communities at Dalaoling National Forest Park Reserve of Yichang were studied qualitatively and quantitatively. The community composition and structure were made clear, the succession courses and stages of the communities were revealed, and the role of these rare trees on the succession course of communities and the cause of being in imminent danger were analyzed, which provided a theoretical basis for protecting the rare trees in the Three-Gorge reservoir area.

NMR studies of Bacillus subtilis tRNA(Trp) hyperexpressed in Escherichia coli. Assignment of imino proton signals and determination of thermal stability

15N-Labeled Bacillus subtilis tRNA(Trp) wild type and a series of mutants were hyperexpressed in Escherichia coli and purified for NMR studies with the use of two-dimensional nuclear Overhauser effect spectroscopy (NOESY) and heteronuclear single quantum correlation (HSQC) and three-dimensional NOESY-HSQC techniques. These made possible chemical shift assignments of imino protons and determination of the thermal stability of the tRNA(Trp) molecules. Almost all of the imino protons in the helical regions and the tertiary base pairs were assigned, except three imino protons of the AU base pairs whose peaks were not clearly observed. Several base triplets found in the crystal structure of tRNA were observed in the present study as well. These studies also revealed two components of tRNA(Trp), which could not be separated by high pressure liquid chromatography, corresponding to s(4)U and U at position 8 of the tRNA(Trp), as indicated by two different sets of peaks for the TpsiC and D arms. The modification at position 8 altered the local conformation of the core region of the tRNA. Thermal unfolding experiments showed that the unfolding process is cooperative in the presence of a high concentration of magnesium ions and that the component corresponding to the s(4)U8 is more stable than the U8 component, thus providing evidence that the thiolation of U8 stabilizes the tertiary structure of tRNA.

Increasing the thermostability of D-xylose isomerase by introduction of a proline into the turn of a random coil

Thermostability can be increased by introducing prolines at suitable sites in target proteins. Two single (G138P, G247D) mutants and one double (G138P/G247D) mutant of xylose isomerase from Streptomyces diastaticus No.7, strain M1033 have been constructed by site-directed mutagenesis. With respect to the wild-type enzyme, G138P showed about a 100% increase in thermostability, and G247D showed an increased catalytic activity. Significantly, the double mutant, G138P/G247D displayed even higher activity than G247D and better heat stability than G138P. Its half life was about 2.5-fold greater than the wild-type enzyme, using xylose as a substrate. Molecular modelling suggested that the introduction of a proline residue in the turn of a random coil may cause the surrounding conformation to be tightened by reducing the backbone flexibility. The change in thermostability can, therefore, be explained based on changes in the molecular rigidity. Furthermore, the improvements in the properties of the double mutant indicated that the advantages of two single mutants can be combined effectively.

Detection of premalignant oral lesions in hamsters with an endoscopic fluorescence imaging system

BACKGROUND

Various methods of detecting cancer with fluorescence have been developed. One type of fluorescence is based on the tumor-localizing properties of certain dyes. However, the phototoxicity of most known tumor-localizing dyes hinders the safe use of such diagnostic methods. The authors have developed a fluorescence imaging system to detect the distribution of a nontoxic dye, fluorescein, and they have evaluated the feasibility of the system by using it to detect oral dysplastic lesions in hamsters.

METHODS

Dysplasia was induced in the cheek pouches of hamsters by application of the carcinogen 9,10-dimethyl-1,2-benzantracene. Fluorescein was administered to the hamsters either intravenously or orally before the fluorescence examination. The endoscopic fluorescence system produced dye-distribution images of both treated and control pouches. Two fluorescence images in different spectral regions were processed for each dye image. Biopsy material from both pouches was examined histopathologically.

RESULTS

The accumulation of fluorescein was detected in 22 of 23 specimens containing dysplastic lesions.

CONCLUSIONS

These results demonstrate the utility of this fluorescein accumulation method in the detection of dysplasia. The accumulation of fluorescein in dysplastic lesions may point to acidification of interstitial medium in such lesions.

Delineation of a membrane-proximal beta-rich domain in the GABAA receptor by progressive deletions

The type A gamma-aminobutyric acid (GABAA) receptor plays a major inhibitory role in the central nervous system. Structural elucidation of the GABAA receptor has been impeded by the large size of the receptor. We present here the delineation of a minimal structural domain as the first step of dissecting the receptor structure. This was achieved through prediction-assisted progressive deletions: the prediction of a candidate structural domain rich in beta-strands with no close similarity to known structures was tested by deleting putative secondary structure elements from the ends of the proposed domain, as well as mutations within the terminal secondary structures. Such progressive deletions revealed the limits of an integral domain, spanning Cys180 to Met293 (numbering of human alpha1 subunit). Below these limits the intact domain structure, as indicated by its circular dichroism, collapses. Based on its putative position, this domain is provisionally designated the membrane-proximal beta-rich domain of GABAA receptor. The inclusion of sequences from the first two out of four previously suggested transmembrane segments and one of the two conserved Cys residues in this domain defines important constraints to the receptor structure.

Possible involvement of P13K in prolactin-stimulated milk product formation and iodide transport in mouse mammary explants

The in vitro effect of wortmannin, an inhibitor of P13 kinase, on prolactin (PRL) stimulated p70S6K, iodide transport, and milk product synthesis were investigated in cultured mouse mammary tissues. Mouse mammary gland explants were initially incubated for 24 hr in media M199 containing 1 microg/ml insulin and 10(-7)M cortisol. A subsequent treatment with wortmannin impeded, in a dose-dependent fashion, the PRL stimulation of casein, lipid, and lactose synthesis as well as the PRL stimulation of iodide transport. Rapamycin (25 ng/ml), an inhibitor of p70S6K, also inhibited the effect of PRL on iodide transport; this drug was earlier shown to inhibit PRL effects on milk product synthesis. These results suggest the possible involvement of p70S6K and P13-kinase in PRL-stimulated milk product formation and iodide transport in mouse mammary explants. Since wortmannin caused a diminished cellular content of p70S6K and a reduced extent of P70S6K migration in polyacrylamide gels (likely due to dephosphorylation), P13-kinase likely lies upstream in the PRL signaling pathway for p70S6K activation.

Fragment of GABA(A) receptor containing key ligand-binding residues overexpressed in Escherichia coli

GABA(A) receptor plays a major role in inhibitory synaptic transmission in the central nervous system and is the target of drugs such as the benzodiazepine tranquilizers. The polymeric membrane protein nature of GABA(A) receptor has rendered structural elucidation of the receptor a formidable task, greatly hampering structure-based drug design. We report here the first expression in Escherichia coli of a fragment of GABA(A) receptor. This 131-residue fragment, spanning Cys166 to Leu296 of human GABAA receptor alpha1 subunit, contains residues previously suggested to be involved in benzodiazepine binding. The overexpressed non-fusion recombinant protein was purified to near homogeneity and characterized by circular dichroism (CD), which showed that the recombinant protein has well defined secondary structures where beta-strands are dominant. The stability of the secondary structures was demonstrated by CD spectra at high pH and elevated temperature. Excluding part of the sequences from the carboxyl terminal of the fragment resulted in dramatic changes in the secondary structures comparable to the effects caused by SDS denaturation. Our results therefore suggest that the 131-residue fragment harbors an integral structural domain of the receptor. The overexpression of the recombinant protein fragment thus opens the way to the biochemical and structural studies of a functionally important region of the receptor, and exemplifies an effective approach of expression and characterization that potentially may be extended to other members of the ligand gated channel receptor superfamily, to which the GABA(A) receptor belongs.

Effect of rapamycin on prolactin-stimulated S6 kinase activity and milk product formation in mouse mammary explants

The in vitro effects of rapamycin on prolactin (PRL)-stimulated S6 kinase activity and milk product synthesis were investigated in cultured mouse mammary tissues. Mouse mammary gland explants were initially incubated for 24 h in M199 media containing 1 microgram/ml insulin and 10(-7) M cortisol. A subsequent treatment of the tissues with 1 microgram/ml PRL for 12 h caused a 98% increase in S6 kinase activity in the cytosolic fraction; effects were not observed at earlier times. PRL at or above 500 ng/ml was needed to elicit a maximum stimulation of S6 kinase activity, and this response was specific for lactogenic hormones (PRL, hPL, hGH). Rapamycin, an inhibitor of 70 K S6 kinase, was employed to assess the possible physiological role of S6 kinase in the PRL stimulation of milk product formation. Rapamycin (25-100 ng/ml) impeded, in a dose-dependent fashion, the PRL stimulation of casein, lipid and lactose synthesis in concert with its inhibition of cytoplasmic S6 kinase activity. These results suggest a possible role for the activation of 70 K kinase in the signalling pathway for the PRL regulation of milk product synthesis in the mammary gland.

Prolactin's effects on lipoprotein lipase (LPL) activity and on LPL mRNA levels in cultured mouse mammary gland explants

The in vitro effects of prolactin (PRL) on lipoprotein lipase (LPL) activity and on LPL mRNA levels were studied in cultured mammary tissues derived from mid-pregnant mice. Mouse mammary gland tissues were initially incubated for 24 hr in M199 media containing 1 microg/ml insulin and 10(-7) M cortisol. A subsequent treatment of the tissues with 1 microg/ml PRL caused a 76% increase in heparin-releasable LPL (hrLPL) activity after 24 hr. A significant increase in LPL activity was detected 16 hr after PRL addition, but not at earlier times. PRL at 100 ng/ml elicited a maximum stimulation of LPL activity. When Northern hybridization techniques were employed, PRL was also found to increase the tissue content of LPL mRNA; this effect was initially detected after a 6-hr PRL treatment employing PRL concentrations of 50 ng/ml and above. Specificity studies revealed that only lactogenic hormones stimulated LPL activity and LPL mRNA accumulation in cultured mammary tissues. PRL also expressed a small (25% increase), but significant, effect on ATP citrate-lyase activity in mammary tissues cultured for more than 6 hr with the hormone.

Capillary-to-fiber surface ratio in rat fast-twitch hindlimb muscles after chronic electrical stimulation

We examined the relative plasticity of capillaries and fiber mitochondria in rat fast-twitch hindlimb muscles in response to chronic electrical stimulation. Specifically we addressed whether the size of the capillary-fiber interface increases in proportion to fiber mitochondrial volume, inasmuch as fiber aerobic capacity increases severalfold with chronic stimulation. Tibialis anterior and extensor digitorum longus muscles of six rats [367 +/- 17 (SD) g body wt] were stimulated (10 Hz, 8 h/day, 7 days/wk) for 28 consecutive days. Subsequently they were perfusion fixed in situ and stimulated, and contralateral control samples from the midbelly were processed for electron microscopy and morphometry. Capillary length density, capillary-to-fiber ratio, and fiber mitochondrial volume density increased two- to threefold in stimulated muscles, with no change in fiber or capillary diameter. Capillary-to-fiber surface area ratio per fiber unit mitochondrial volume was unchanged in stimulated muscles compared with contralateral controls, indicating a proportional increase in the size of the capillary-fiber interface and fiber mitochondrial volume in the muscles after chronic electrical stimulation.

VEGF gene expression is upregulated in electrically stimulated rat skeletal muscle

Vascular endothelial growth factor (VEGF; also called vascular permeability factor) is a secreted mitogen with distinct target cell specificity for vascular endothelial cells. Hypoxia upregulates VEGF expression, making it a likely mediator of the angiogenesis that occurs in poorly perfused tissues. The purpose of this study was to determine whether VEGF gene expression is upregulated in chronically stimulated skeletal muscles, where hypoxia is thought to trigger the growth of blood vessels. The right anterior tibialis and extensor digitorum longus muscles of 12 rats were stimulated electrically (10 Hz, 300 microseconds pulses) for up to 21 days by way of the peroneal motor nerve. The contralateral muscles served as control. Northern analysis showed that VEGF mRNA levels increased by approximately sixfold after 4 days of stimulation and then decreased gradually over the next several days. VEGF mRNA levels were still elevated by two- to threefold after 21 days of stimulation. Higher VEGF mRNA levels in the early stages of muscle stimulation and gradually decreasing levels in later stages are consistent with a metabolic hypothesis in which tissue oxygenation controls VEGF expression. These studies support the hypothesis that VEGF has a physiological role in promoting angiogenesis in stimulated skeletal muscle.

Long-term electrical stimulation of rabbit skeletal muscle increases growth of paired arteries and veins

We tested whether chronic stimulation of skeletal muscle can increase the growth of paired arteries and veins in rabbit extensor digitorum longus muscle (EDL). The right EDL of female New Zealand White rabbits was stimulated via the common peroneal nerve at 10 Hz using 300 microseconds square waves at 3-4 V. Two-hour periods of stimulation was alternated with 4-h periods of rest, 7 days/wk for approximately 60 days. The left EDL served as control. The hindlimb vascular system was maximally dilated and perfuse-fixed with 3% glutaraldehyde and 2% paraformaldehyde at arterial and venous pressures of 80-100 and 15-20 mmHg, respectively. Muscles were postfixed in OsO4 and embedded in EPOX 812 resin. One millimeter-thick transverse sections were cut at uniform locations through the entire breadth of the muscle and analyzed using videomicroscopy along with computerized morphometric and stereological techniques. All paired arteries and veins on each full muscle section were analyzed. Chronic muscle stimulation caused the wall volume of paired arteries and veins to increase by an average of approximately twofold and the lumen volume to increase by an average of approximately threefold compared with the contralateral muscles. The wall-to-lumen area ratio of the arteries and veins was not affected. Muscle stimulation also caused the numerical density of arteries having a diameter > 100 microns to increase by approximately fourfold and the density of veins having a perimeter > 500 microns to increase by approximately 10-fold.(ABSTRACT TRUNCATED AT 250 WORDS)

Miniaturized electrical stimulator with controllable duty cycles

A stimulator with adjustable duty cycles is described for chronic electrical stimulation of skeletal muscles by way of a motor nerve. The stimulator is unique in that it can stimulate a muscle or group of muscles for 2-h intervals that alternate with variable periods of rest (2, 4, 6, 8, or 10 h). A given duty cycle is selected with a rotary switch at the beginning of an experiment and will continue automatically, without human intervention, for the duration of the experiment. Other features include an adjustable voltage output, a stimulation indicator light-emitting diode (LED), and a low-battery indicator LED. The stimulator is powered by two 9-V batteries or can be used with a bench-top power supply. The stimulation frequency (10 Hz) and pulse width (300 microseconds) are fixed in our design but can be changed to other values by substituting two of the resistors and one capacitor in accordance with simple formulas. We have used the stimulator in rat and rabbit experiments to stimulate the anterior tibialis and extensor digitorum longus muscles for up to 60 days. The timing and output of the stimulator were found to be stable and accurate over the entire 60-day period. The stimulator and batteries were carried in a jacket worn by the rabbits. In the rat experiments, the stimulator was used in a remote fashion with the electrical leads connected to the animals by way of a tethering system. In both animals, the electrodes were implanted adjacent to the common peroneal nerve.(ABSTRACT TRUNCATED AT 250 WORDS)

A stereological method for estimating length density of the arterial vascular system

We developed a stereological method for quantitating length density (Lv; vessel length per unit reference volume) of the arterial system. Accurate estimation of Lv for a sparse system of blood vessels in a three-dimensional specimen requires information on individual vessel orientation. The method we present extracts the necessary information on vessel orientation from profile geometry. Major and minor diameters of elliptical profiles of sectioned tubular structures are used to calculate Lv. The method does not require special sectioning alignment and does not assume a prior distribution of blood vessels; however, the method does assume that arteries are cylindrical. A physical model consisting of boiled spaghetti mixed with agar in a cylinder was used to test the stereological method. Measurements of over 1,000 elliptical profiles in 5 separate trials have demonstrated that the method can accurately estimate Lv with < 5% error even when tortuosity is high, i.e., when anisotrophy coefficient is 1.55. This method may facilitate a better understanding of the mechanisms of artery growth by making it possible to quantify linear growth of the arterial system.

Evidence for heat-stable liver cytosol substance(s) capable of causing oxidative activation of fructose 1,6-bisphosphatase

The endogenous fructose 1,6-bisphosphatase (FBPase) in chicken liver extract undergoes a drastic increase in activity if the pH of the extract is in the alkaline range. Greater and more consistent activation occurs when purified FBPase, placed inside dialysis sack, is incubated in liver extract. Maximal activation (over 16-fold) is accompanied by the disappearance of 4 highly reactive sulfhydryl groups (SH) per molecule of enzyme. The activating effect of the extract remains essentially unchanged after heating to 100 degrees C. Activation can be reversed by dithiothreitol. These data show the existence in liver cytosol of heat-stable substance(s) capable of activating FBPase presumably by forming disulfide bonds with the enzyme's highly reactive SH groups.