[Real-time localization for port-implanted catheter tip by echocardiographic guidance]

The clinical data of 23 patients undergoing real-time echocardiography-guided infusion port implantation in the Breast Center of Tsinghua Changgung Hospital in Beijing from January to July 2021 were analyzed. The length of catheter insertion L1 was initially estimated using surface measurement method in all patients. Intraoperatively, transthoracic echocardiography was applied using the parasternal four-chamber view to visualize the catheter image within the right atrium, and the length of catheter insertion L2 was recorded under the guidance of echocardiography. Postoperatively, chest radiographs were taken in the upright position to observe the position of the catheter tip. According to chest CT scans, the ideal length (L) for catheter tip placement was calculated when it was located at the junction of superior vena cava and right atrium. Bland-Altman scatter plot analysis and linear regression fitting test were used on L1 and L2 respectively with L to evaluate the consistency. A total of 23 patients were included in this study, among which one case of left breast cancer patient undergoing breast-conserving surgery had difficulty in identifying the catheter tip position due to residual pleural effusion obscuring the imaging of the cardiac apex four-chamber view. In 22 patients, the results of intraoperative ultrasound imaging were good, including 1 case of catheter ectopic to azygos vein, and 21 cases of right atrial catheter could be detected by ultrasound. Statistical analysis showed that there was a good consistency between L1 and L, L2 and L, and the difference between them was d=0.28 cm (95%CI:-1.76-2.31 cm) and d=0.20 cm(95%CI:-0.84-1.23 cm), respectively, with no statistical significance (P>0.05). In the linear regression model, L2 and L had a higher fit than L1, and the difference was statistically significant (R²=0.954, P<0.001). This study found that real-time echocardiographic localization technique can be applied in adult port surgery to replace X-ray-guided real-time catheter tip detection and adjustment to the optimal position.

[Application of transbronchial cryobiopsy in the diagnosis of postoperative complications after lung transplantation: a report of 6 cases]

Objective: To investigate the efficacy and safety of transbronchial cryobiopsy (TBCB) after lung transplantation. Methods: The clinical characteristics, TBCB procedure, diagnosis and treatment, and outcomes of lung transplant recipients of 6 patients (all male, aged 33-67 years) with TBCB in China-Japan Friendship Hospital from May to November 2021 were retrospectively analyzed. Results: Among the 6 patients diagnosed by TBCB, there were 2 cases of organizing pneumonia, 1 acute cellular rejection, 1 antibody-mediated rejection, and 1 bronchiolitis obliterans, and 1 diffuse alveolar damage. After the clinical diagnosis was confirmed, the condition improved after adjustment of the treatments followed. There were no serious complications related to the TBCB procedure. Conclusion: TBCB is valuable and relatively safe in the diagnosis of complications after lung transplantation, but the indications need to be strictly controlled.

[Pneumatosis cystoides intestinalis in lung transplant recipients: three cases report and literature review]

Objective: To report the clinical characteristics and treatment courses of pneumatosis cystoides intestinalis(PCI) after lung transplantation(LT). Methods: We included all cases of PCI after LT from March 2017 to June 2021 in China-Japan Friendship Hospital. In addition to our cases, we searched literatures published in Chinese and English languages using China National Knowledge Infrastructure (CNKI), Wanfang Data and PubMed/MEDLINE with the search terms"pneumatosis intestinalis"and"lung transplantation". The clinical characteristics and treatment courses of all cases were summarized and analyzed. Results: Three cases of PCI occurred after LT in this study, with an incidence of 0.804% (3/373). Thirteen related literatures were retrieved, with 51 cases enrolled. The median age of the 54 patients was 55.4 years (22-79 years), with 33 males and 21 females. 64.81% (35/54) of the 54 patients underwent LT for interstitial lung disease and 90.74% (49/54) underwent bilateral LT. Twenty-two cases(40.7%) were asymptomatic when PCI occurred. Thirty-eight cases (38/54,70.37%)had involvement of ascending colon, and 35 cases(35/54,64.81%)had involvement of transverse colon. Forty-three cases(43/54, 79.63%) were treated conservatively. The average interval between transplantation and PCI was 210 (5-2 495) days. Conclusion: PCI is a rare complication after lung transplantation, most often occurring in the colon. Most patients were asymptomatic and could improve by conservative treatments.

Artificial intelligence for detecting superficial esophageal squamous cell carcinoma under multiple endoscopic imaging modalities: A multicenter study

BACKGROUND AND AIM

Diagnosis of esophageal squamous cell carcinoma (ESCC) is complicated and requires substantial expertise and experience. This study aimed to develop an artificial intelligence (AI) system for detecting superficial ESCC under multiple endoscopic imaging modalities.

METHODS

Endoscopic images were retrospectively collected from West China Hospital, Sichuan University as a training dataset and an independent internal validation dataset. Images from other four hospitals were used as an external validation dataset. The AI system was compared with 11 experienced endoscopists. Furthermore, videos were collected to assess the performance of the AI system.

RESULTS

A total of 53 933 images from 2621 patients and 142 videos from 19 patients were used to develop and validate the AI system. In the internal and external validation datasets, the performance of the AI system under all or different endoscopic imaging modalities was satisfactory, with sensitivity of 92.5-99.7%, specificity of 78.5-89.0%, and area under the receiver operating characteristic curves of 0.906-0.989. The AI system achieved comparable performance with experienced endoscopists. Regarding superficial ESCC confined to the epithelium, the AI system was more sensitive than experienced endoscopists on white-light imaging (90.8% vs 82.5%, P = 0.022). Moreover, the AI system exhibited good performance in videos, with sensitivity of 89.5-100% and specificity of 73.7-89.5%.

CONCLUSIONS

We developed an AI system that showed comparable performance with experienced endoscopists in detecting superficial ESCC under multiple endoscopic imaging modalities and might provide valuable support for inexperienced endoscopists, despite requiring further evaluation.

[Clinical value of TDI combined with 2D-STI on evaluating the microcirculation dysfunction and left ventricular dysfunction in patients with non-obstructive coronary angina]

Objective: To explore the value of tissue Doppler imaging (TDI) combined with two-dimensional speckle tracking imaging (2D-STI) at rest on evaluating microcirculation dysfunction and left ventricular dysfunction in patients with angina and no obstructive coronary artery disease(ANOCA). Methods: This retrospective study recruited 78 ANOCA patients, who hospitalized in the People's Hospital of Liaoning Province from August 2019 to July 2021. These patients underwent conventional echocardiography examination, including TDI and 2D-STI, to evaluate the left ventricular dysfunction, and adenosine stress echocardiography (SE) to evaluate the coronary flow velocity reserve (CFVR). ANOCA patients were divided into coronary microcirculation dysfunction CMD group (CFVR<2) and control group (CFVR≥2) according to CFVR. Clinical data, routine echocardiographic parameters, TDI parameters including isovolumic contraction time (IVCT), isovolumic relaxation time (IVRT), ejection time (ET), and STI parameters including global longitudinal peak strain (GLS), time to peak (TTP); peak strain dispersion (PSD) were compared between the two groups. Binary logistic regression was used to analyze the risk factors of CMD and the predictive value of each parameter to construct a joint prediction model for the diagnosis of CMD in this patient cohort. Results: The mean age was (55.5±11.2) years, 43 (55%) patients were females in this patient cohort, 38 (49%) patienst were didvided into the CMD group and 40 (51%) into the control group. Age, prevalence of hypertension, diabetes, dyslipidemia, and smokers were significantly higher in the CMD group than in the control group (all P<0.05). Tei index was higher, IVCT and TTP were longer, PSD was higher, ET was shorter, and absolute GLS was lower in the CMD group than in the control group (all P<0.05). The results of logistic regression analysis showed that longer IVCT, higher Tei index, higher time to PSD and lower absolute GLS were the independent risk factors of CMD. The ROC curve revealed that the predicting efficacy on CMD was satisfactiory with the combined predictors: AUC=0.884, sensitivity of 82% and specificity of 80%. Conclusions: TDI combined with 2D-STI is associated with a good diagnostic value on the diagnosis of CMD and left ventricular dysfunction in patients with ANOCA, which provides a feasible non-invasive tool for the diagnosis of CMD and risk stratification of patients with ANOCA.

Four-Component Reaction Access to Nitrile-Substituted All-Carbon Quaternary Centers

A four-component reaction strategy for access to acyclic nitrile-substituted all-carbon quaternary centers is disclosed. In the presence of a DABCO-based ionic liquid catalyst, the reactions proceed smoothly with a wide range of substrates efficiently to deliver nitrile-substituted all-carbon quaternary centers under mild reaction conditions. This protocol is further demonstrated as an efficient method for the construction of contiguous all-carbon quaternary centers. All the reactions are easily operated in a green manner, producing water as the only byproduct. Some of the products show excellent activity against specific fungi.

[Pulmonary mucormycosis after lung transplantation:3 cases report with literature review]

Objective: To report the risk factors, clinical characteristics and treatment courses of pulmonary mucormycosis after lung transplantation(LT). Methods: We included 3 cases with pulmonary mucormycosis after LT from March 2017 to July 2020 in the centre for lung transplantation of China-Japan Friendship Hospital. Twelve cases from Chinese and English literature from China National Knowledge Infrastructure (CNKI), China Biomedical Literature Service System and Pubmed Database from March 1980 to July 2020 were added. The risk factors, clinical characteristics and treatment courses of all cases were summarized and analyzed. Results: Pulmonary mucormycosis occurred in 1.06% (3/284) in our centre. A total of 15 cases with 12 cases from literature included 10 males and 5 females with a mean age of(47±20)years. Thirteen cases occurred after LT, and 2 cases occurred after heart-lung transplantation (HLT). Nine probable cases were diagnosed by positive isolation of the pathogen from bronchoalveolar lavage fluid or sputum. Three proven cases were diagnosed by transbronchial lung biopsy. Meanwhile, the other 3 proven cases diagnosed by CT-guided percutaneous lung biopsy, autopsy and surgical operation respectively. Ten cases (66.7%) were diagnosed with pulmonary mucormycosis within 90 days after lung transplantation. The mortality was as high as 46.67% (7/15), but if it occurred within 90 days, the mortality reached 70% (7/10). The average interval between transplantation and positive isolation of the pathogen was 112.3 (5-378) days. Conclusions: The clinical and radiographic features of pulmonary mucormycosis after LT were nonspecific. It had a high mortality, especially in those occurred within 90 days after LT. The combination of antifungal therapy and surgical resection may contribute to a better outcome of the disease.

[Prevalence of CYP2C19 gene mutations in patients with coronary heart disease and its biological activation effect in clopidogrel antiplatelet response]

Objective: The purpose of this study was to investigate the effects of CYP2C19 gene mutations on clopidogrel antiplatelet activity in the patients with coronary heart disease treated by percutaneous coronary intervention. Methods: Patients with coronary heart disease, who hospitalized in the Second Affiliated Hospital of Nanchang University from March 2011 to June 2019, and healthy individuals with matching genetic background, gender, and age as controls were included in this study. Basic clinical data were analyzed and blood samples of all research subjects were obtained for extraction of DNA, and Sanger first-generation sequencing method was used to detect CYP2C19 gene mutation from full exon and exon and intron junction. CYP2C19 gene variations in patients with coronary heart disease were compared with the 1000 Genomes Browse database and the sequencing results of healthy controls to determine whether the gene variation was a genetic mutation or a genetic polymorphism. After that, PolyPhen-2 prediction software was used to analyze the harmfulness of gene mutations to predict the effect of mutations on protein function. The same dose of CYP2C19 wild-type plasmid and the CYP2C19 gene mutant plasmids were transfected into human normal liver cells HL-7702. After transfection of 24 h, the expression of CYP2C19 protease in each group was detected. The liver S9 protein was incubated with clopidogrel, acted on platelets to detect the platelet aggregation rate and the activity of human vasodilator-activated phosphoprotein (VASP). Results: A total of 1 493 patients with coronary heart disease (59.36%) were enrolled, the average age was (64.5±10.4) years old, of which 1 129 were male (75.62%). Meanwhile, 1 022 healthy physical examination volunteers (40.64%) were enrolled, and the average age was (64.1±11.0) years old, of which 778 were male (76.13%). A total of 5 gene mutations of CYP2C19 gene were identified in 12 patients (0.80%), namely, 4 known mutations T130K (1 case), M136K (6 cases), N277K (3 cases), V472I (1 case) and one new mutation G27V (1 case), no corresponding gene mutation was found in healthy controls. It was found that T130K and M136K were probably damaging, G27V was possibly damaging, and N277K and V472I were benign mutations. In vitro, we demonstrated that the platelet aggregation rate of the M136K gene mutation group was 24.83% lower than that of the wild type (59.58% vs. 34.75%; P<0.05), and the phosphorylated VASP level was 23.0% higher than that of the wild type (1.0 vs. 1.23; P<0.05). However, the platelet aggregation rate and phosphorylated VASP level were similar between of G27V, T130K, N277K, V472I gene mutation groups and wild type group (P>0.05). Conclusions: In this study, 5 gene mutations are defined in patients with coronary heart disease, namely G27V, T130K, M136K, N277K, V472I. In vitro functional studies show that CYP2C19 gene mutation M136K, as a gain-of-function gene mutation, can enhance the activation of CYP2C19 enzyme on clopidogrel, thereby inhibiting the platelet aggregation rate.

Endoscopic palliative resection of a giant 26-cm esophageal tumor: A case report

BACKGROUND

Esophageal carcinosarcoma, usually presenting as a pedunculated polypoid mass, is a rare malignancy with coexisting sarcomatoid and carcinomatous components. Its imaging and endoscopic characteristics are similar to those of leiomyosarcoma, liposarcoma and so forth. The diagnosis needs histological confirmation. Surgical resection is the traditional therapy. Endoscopic resection is minimally invasive but still controversial. This paper reports the case of a patient with a giant esophageal carsinosarcoma who underwent a palliative endoscopic resection.

CASE SUMMARY

A 55-year-old male patient presented with dysphagia and weight loss for 1 mo. Imaging and endoscopy showed a gray-white, polypoid, stalk-like mass, with a bulky pedicle located in the middle and lower esophagus. The mass almost filled the whole esophageal lumen, but the endoscope could still pass through. Despite the suspicion of a malignancy, repeated biopsies indicated necrosis and inflammation. After multidisciplinary team consultation, an endoscopic resection to diagnose and relieve the obstruction was recommended. The pedicle of the mass was cut off, the bleeding was stopped, and the mass was cut into pieces and pulled out. The mass was 26 cm × 5 cm × 4 cm in size. The final diagnosis was esophageal carcinosarcoma. No postoperative complications occurred. After 1 mo, the patient gained 6 kg and endoscopic reexamination revealed no obstruction. Radical surgery with lymph node dissection was carried out successfully. This lesion was the largest endoscopically resected esophageal carcinosarcoma reported to date.

CONCLUSION

Endoscopic palliative resection can help obtain adequate tissue for diagnosis and relieve obstructions in patients with giant esophageal carcinosarcoma.

Artificial intelligence-assisted esophageal cancer management: Now and future

Esophageal cancer poses diagnostic, therapeutic and economic burdens in high-risk regions. Artificial intelligence (AI) has been developed for diagnosis and outcome prediction using various features, including clinicopathologic, radiologic, and genetic variables, which can achieve inspiring results. One of the most recent tasks of AI is to use state-of-the-art deep learning technique to detect both early esophageal squamous cell carcinoma and esophageal adenocarcinoma in Barrett’s esophagus. In this review, we aim to provide a comprehensive overview of the ways in which AI may help physicians diagnose advanced cancer and make clinical decisions based on predicted outcomes, and combine the endoscopic images to detect precancerous lesions or early cancer. Pertinent studies conducted in recent two years have surged in numbers, with large datasets and external validation from multi-centers, and have partly achieved intriguing results of expert’s performance of AI in real time. Improved pre-trained computer-aided diagnosis algorithms in the future studies with larger training and external validation datasets, aiming at real-time video processing, are imperative to produce a diagnostic efficacy similar to or even superior to experienced endoscopists. Meanwhile, supervised randomized controlled trials in real clinical practice are highly essential for a solid conclusion, which meets patient-centered satisfaction. Notably, ethical and legal issues regarding the black-box nature of computer algorithms should be addressed, for both clinicians and regulators.

Risk factors for distal migration of biliary plastic stents and related duodenal injury

BACKGROUND

The risk factors of duodenal injury from distal migrated biliary plastic stents remain uncertain. The aim of this study was to determine the risk factors of distal migration and its related duodenal injury in patients who underwent placement of a single biliary plastic stent for biliary strictures.

METHODS

We retrospectively reviewed all patients with biliary strictures who underwent endoscopic placement of a single biliary plastic stent from January 2006 to October 2017.

RESULTS

Two hundred forty-eight patients with 402 endoscopic retrograde cholangiopancreatography procedures were included. The incidence of distal migration was 6.2%. The frequency of duodenal injury was 2.2% in all cases and 36% in cases with distal migration. Benign biliary strictures (BBS), length of the stent above the proximal end of the stricture (> 2 cm), and duration of stent retention (< 3 months) were independently associated with distal migration (p = 0.018, p = 0.009, and p = 0.016, respectively). Duodenal injury occurred more commonly in cases with larger angle (≥ 30°) between the distal end of the stent and the centerline of the patient's body (p = 0.018) or in cases with stent retention < 3 months (p = 0.031).

CONCLUSIONS

The risk factors of distal migration are BBS and the length of the stent above the proximal end of the stricture. The risk factor of duodenal injury due to distal migration is large angle (≥ 30°) between the distal end of the stent and the centerline of the patient's body. Distal migration and related duodenal injury are more likely to present during the early period after biliary stenting.

Real-time automated diagnosis of precancerous lesions and early esophageal squamous cell carcinoma using a deep learning model (with videos)

BACKGROUND AND AIMS

We developed a system for computer-assisted diagnosis (CAD) for real-time automated diagnosis of precancerous lesions and early esophageal squamous cell carcinomas (ESCCs) to assist the diagnosis of esophageal cancer.

METHODS

A total of 6473 narrow-band imaging (NBI) images, including precancerous lesions, early ESCCs, and noncancerous lesions, were used to train the CAD system. We validated the CAD system using both endoscopic images and video datasets. The receiver operating characteristic curve of the CAD system was generated based on image datasets. An artificial intelligence probability heat map was generated for each input of endoscopic images. The yellow color indicated high possibility of cancerous lesion, and the blue color indicated noncancerous lesions on the probability heat map. When the CAD system detected any precancerous lesion or early ESCCs, the lesion of interest was masked with color.

RESULTS

The image datasets contained 1480 malignant NBI images from 59 consecutive cancerous cases (sensitivity, 98.04%) and 5191 noncancerous NBI images from 2004 cases (specificity, 95.03%). The area under curve was 0.989. The video datasets of precancerous lesions or early ESCCs included 27 nonmagnifying videos (per-frame sensitivity 60.8%, per-lesion sensitivity, 100%) and 20 magnifying videos (per-frame sensitivity 96.1%, per-lesion sensitivity, 100%). Unaltered full-range normal esophagus videos included 33 videos (per-frame specificity 99.9%, per-case specificity, 90.9%).

CONCLUSIONS

A deep learning model demonstrated high sensitivity and specificity for both endoscopic images and video datasets. The real-time CAD system has a promising potential in the near future to assist endoscopists in diagnosing precancerous lesions and ESCCs.

[A single-center experience of venous thromboembolism after adult lung transplantation]

Objective: To investigate the incidence of venous thromboembolism (VTE) in lung transplant (LT) recipients. Methods: The clinical data on 124 consecutive patients who underwent lung transplant at Lung Transplantation Center of China-Japan Friendship Hospital from March 2017 to September 2018 were retrospectively collected. Deep venous thrombosis (DVT) was ascertained by vascular ultrasound. Pulmonary embolism (PE) was diagnosed by either chest computed tomography pulmonary angiogram or ventilation/perfusion scan. The risk factors in those patients with postoperative VTE were studied. Results: A total of 124 lung transplant recipients including 78 single lung transplant recipients (62.9%) and 46 bilateral lung transplant recipients(37.1%) were enrolled. Preoperative and postoperative prophylactic anticoagulant was used in 52 patients(52/124, 41.9%) and 69 patients(69/124, 55.6%) respectively. Thirty-two patients developed postoperative VTE among 124 consecutive patients. The overall incidence rate of VTE among 124 LT recipients was 25.8%. The median time to VTE episode following lung transplant was 22.5 days (range 4-295 days). The percentage of DVT in VTE was 93.8%(30/32), involving 1-8 (2.83±1.86) veins. And 60.0% of DVT was from lower extremities and 56.7% located in upper extremities (P>0.05). Four patients (4/32,12.5%) had PE episodes, and half of them suffered from only PE without DVT. The use of extracorporeal membrane oxygenation (ECMO) in 32 patients with VTE was 90.6% (29/32), which was significantly higher than that without VTE (64/92,69.6%, P=0.033). However, there was no difference in the use of peripherally inserted central catheter (PICC) between two groups (96.9% vs 81.5%, P=0.067). Resolution of VTE was successfully accomplished by anticoagulant therapy with long-term use of low molecular weight heparin in 30 patients (93.7%) and followed by oral warfarin in 2 patients (6.3%). Three months follow-up data after anticoagulant therapy showed that total and partial vascular recanalization rate was 65.6%(21/32) and 34.4%(11/32), respectively. Despite anticoagulation-related bleeding complications in three patients, no serious consequences occurred. Conclusions: VTE was frequent in LT recipients. It was speculated that ECMO utilization may be a major risk factor for high incidence of VTE in LT recipients. Aggressive VTE screening/treatment protocols were suggested to be implemented in LT recipients.

[Relationship between angiopoietin-2 and vascular endothelial factor and vasodilation function in hypertensive patients]

Objective: To analyze the relationship between angiopoietin 2 (Ang2) and vascular endothelial factor and vasodilation function in hypertensive patients. Methods: Patients with new onset grade 1~2 hypertension (n=40) and healthy control group (n=25) wereenrolledprospectively. Serum Ang2 and nitric oxide (NO), nitric oxide synthase (eNOS), endothelin-1 (ET-1) were measured in both groups. Flow-mediated vasodilation (FMD) were measured in hypertensive patients. The above indicators were reviewed in hypertensive patients after antihypertensive treatment until blood pressure<140/90 mmHg. Results: Compared with the control group, serum Ang2 (P=0.049) and ET-1 (P<0.001) were significantly higher. Serum NO (P<0.001) and eNOS (P<0.001) was significantly lower in the hypertensive group. Compared with baseline, serum Ang2 (P=0.049) and ET-1 (P<0.001) were decreased significantly, meanwhile serum NO (P<0.001) and eNOS (P<0.001) were significantly increased. Serum Ang2 after antihypertensive treatment was not significantly different from that of the control group, but no statistical difference was observed in FMD after antihypertensive therapy. Correlation analysis found that serum Ang2 was positively correlated with mean arterial pressure (R=0.432, P<0.001), and negative correlated with serum NO(R=-0.374, P=0.001) and FMD (R=-0.368 0, P=0.002). Multiple linear regression found that serum Ang2 was independently associated with body mass index, mean arterial pressure, and serum NO. Conclusion: Serum Ang 2 can reflect the degree of endothelial and vasodilation impairment in hypertensive patients. Antihypertensive therapy can improve endothelial function, but whether it can restore damaged vasodilation function needs further verification.

[Related factors for the development of fulminant myocarditis in adults]

Objective: To determine the early recognizable factors related to patients with fulminant myocarditis. Methods: Medical records from 60 adult patients who were diagnosed with acute viral myocarditis from January 2003 to September 2016 in our hospital were retrospectively reviewed, and divided into the fulminant group (n=9) and the non-fulminant group (n=51). Clinical presentations, biochemical markers, electrocardiography and echocardiography features on admission were analyzed. Results: Prevalence of syncope (33.3%(3/9) vs. 2.0% (1/51), P=0.009) and fatigue (77.8% (7/9) vs. 21.6% (11/51) , P=0.002) was significantly higher, while the duration from flu-like syndromes to chest discomfort was shorter ((2.0±1.8) days vs. (4.5±3.5) days, P=0.041) in the fulminant group than that in the non-fulminant group. Systolic blood pressare (SBP) ((94±14) mmHg(1 mmHg=0.133 kPa) vs. (117±12)mmHg, P=0.001) and left ventricular ejection fraction((49±12)% vs. (60±13)%, P=0.016) were significantly lower, while heart rate ((99±20)bpm vs. (84±19)bpm, P=0.040) and NT-proBNP concentration ((7 962 (1 470, 23 849) ng/L vs. 1 771 (45, 2 380) ng/L, P=0.000) were significantly higher in the fulminant group than those in the non-fulminant group. PR interval was longer (199 (140, 416) ms vs. 156 (112, 204) ms, P=0.021), QRS complex was wider ((127±14)ms vs. (95±13)ms, t=-6.647, P<0.001) in the fulminant group than those in the non-fulminant group. Prolonged QRS duration≥120 ms was more often in fulminant group (77.8%(7/9) vs. 5.9%(3/51), P=0.000). Multivariate analysis revealed that PR interval (adjusted odd ratio 1.044, 95%CI 1.005-1.084, P=0.025) and QRS complex width (adjusted odd ratio 1.252, 95%CI 1.045-1.501, P=0.015) were the independent risk factors significantly associated with fulminant myocarditis. Conclusions: The risk of a fulminant course of acute myocarditis is higher in patients with elevated NT-proBNP, reduced left ventricular ejection fraction, and conduction disturbances at admission. Prolonged PR interval and widened QRS complex on admission are independent risk factors for developing fulminant myocarditis in adult patients with acute viral myocarditis.

[Feasibility and value of index of microcirculatory resistance in patients with acute myocardial infarction after primary percutaneous coronary intervention]

Objective: To evaluate the feasibility of detecting index of microcirculatory resistance (IMR) and the relationship between IMR and left ventricular (LV) systolic function after acute myocardial infarction (AMI) undergoing primary percutaneous coronary intervention (PCI). Methods: The patients with first AMI received primary PCI in Peking University Third Hospital were enrolled from January 2014 to March 2016. IMR were measured immediately after PCI by using pressure/temperature wire. The relationship between IMR and left ventricular ejection fraction (LVEF) assessed by echocardiography at first day and 6 months after admission was evaluated. Results: Twenty-eight patients with anterior wall AMI were enrolled, with an average age (56±13) years. The success rate of IMR detection was 100%. The mean IMR was (33±18 )mmHg·s. There was no complication related to intravenous adenosine triphosphate (ATP) (140 μg· kg(-1)· min(-1)). The IMR was negatively correlated with TIMI blood flow grade after primary PCI (r=-0.386, P=0.043), and positively correlated with female gender, CK peak value and TnT peak value (r=0.430, P=0.022; r=0.431, P=0.025; r=0.434, P=0.024). After 6 months of follow-up, no adverse cardiovascular events (including cardiac death, nonfatal myocardial infarction, malignant arrhythmia, unplanned revascularization, hospitalization for unstable angina pectoris and severe heart failure requiring hospitalization) occurred. LVEF increased significantly compared with the first day after PCI (0.54±0.08 vs 0.47±0.06, P=0.001), and IMR was negatively correlated with LVEF after 6 months (r=-0.477, P=0.014). Multivariable linear regression analysis showed that CK peak and IMR were predictors of LVEF after six months ( β=-0.595, t=-3.814, P=0.01; β=-0.352, t=-2.26, P=0.036). Conclusions: Immediate detection of IMR in patients with anterior wall AMI after PCI is safe and feasible. The immediate IMR after PCI reflects the extent of myocardial necrosis and myocardial perfusion, and is a predictor of LVEF at 6 months after PCI.

Abnormal Multiple Charge Memory States in Exfoliated Few-Layer WSe2 Transistors

To construct reliable nanoelectronic devices based on emerging 2D layered semiconductors, we need to understand the charge-trapping processes in such devices. Additionally, the identified charge-trapping schemes in such layered materials could be further exploited to make multibit (or highly desirable analog-tunable) memory devices. Here, we present a study on the abnormal charge-trapping or memory characteristics of few-layer WSe₂ transistors. This work shows that multiple charge-trapping states with large extrema spacing, long retention time, and analog tunability can be excited in the transistors made from mechanically exfoliated few-layer WSe₂ flakes, whereas they cannot be generated in widely studied few-layer MoS₂ transistors. Such charge-trapping characteristics of WSe₂ transistors are attributed to the exfoliation-induced interlayer deformation on the cleaved surfaces of few-layer WSe₂ flakes, which can spontaneously form ambipolar charge-trapping sites. Our additional results from surface characterization, charge-retention characterization at different temperatures, and density functional theory computation strongly support this explanation. Furthermore, our research also demonstrates that the charge-trapping states excited in multiple transistors can be calibrated into consistent multibit data storage levels. This work advances the understanding of the charge memory mechanisms in layered semiconductors, and the observed charge-trapping states could be further studied for enabling ultralow-cost multibit analog memory devices.

Epidemiological features of gastroenteropancreatic neuroendocrine tumors in Chengdu city with a population of 14 million based on data from a single institution

AIM

Recent studies on gastroenteropancreatic neuroendocrine tumors (GEP-NETs) in the United States as well as the European studies demonstrate an increasing GEP-NETs incidence. Most information on the epidemiology of neuroendocrine tumors comes from western countries. However, the epidemiological profile of GEP-NETs in West China is still unclear. The aim of study was to reflect the regional features of GEP-NETs in Chengdu city of West China based on data from a single institution.

METHODS

West China Hospital (WCH), the largest university hospital located in Chengdu (West China) with population of 14.04 million, has established a serial of databases in recent years. According to the data from Medical Records Section of WCH and Chengdu Health Bureau, the total patients per year in WCH covered about 25.6-28% patients of Chengdu city during the 5 years. Therefore, we have used GEP-NETs diagnosed in WCH from 2009 to 2013 to reflect the regional epidemiological profile of GEP-NETs.

RESULTS

GEP-NETs proportion in WCH increased 1.6-folds during past 5 years from 1.28/10(5) to 2.03/10(5) , P < 0.05. The average duration of symptom before diagnosis was 16.8 months. About 46.6% (115/248) of GEP-NETs were metastatic. Seventy-seven percent (190/248) of patients were over 40 years. Proportions of GEP-NETs from primary sites were rectum 30.6% (76/248), pancreas 23.4% (58/248), gastric 13.3% (33/248) and esophagus 11.3% (28/248). Proportions of insulinoma, vipoma and nonfunctional pancreatic neuroendocrine tumors (P-NETs) were 43.1% (25/58), 1.7% (1/58) and 55.2% (32/58) separately in the P-NETs.

CONCLUSIONS

There is a distinct epidemiologic profile between West China and western countries based on a single institution data. The delayed diagnosis reflects inadequate disease awareness of GEP-NETs and paucity of research funding.

Somatostatin analogues do not prevent carcinoid crisis

BACKGROUND

Carcinoid crisis is a life-threatening syndrome of neuroendocrine tumors (NETs) characterized by dramatic blood pressure fluctuation, arrhythmias, and bronchospasm. In the era of booming anti-tumor therapeutics, this has become more important since associated stresses can trigger carcinoid crisis. Somatostatin analogues (SSTA) have been recommended for prophylactic administration before intervention procedures for functioning NETs. However, the efficacy is still controversial. The aim of this article is to review efficacy of SSTA for preventing carcinoid crisis.

MATERIALS AND METHODS

PubMed, Cochrane Controlled trials Register, and EMBASE were searched using 'carcinoid crisis' as a search term combining terms with 'somatostatin'; 'octreotide'; 'lanreotide' and 'pasireotide' until December 2013.

RESULTS

Twenty-eight articles were retrieved with a total of fifty-three unique patients identified for carcinoid crisis. The most common primary sites of NETs were the small intestine and respiratory tract. The triggering factors for carcinoid crisis included anesthesia/ surgery (63.5%), interventional therapy (11.5%), radionuclide therapy (9.6%), examination (7.7%), medication (3.8%), biopsy (2%) and spontaneous (2%). No randomized controlled trials (RCTs) were identified and two case-control studies were included to assess the efficacy of SSTA for preventing carcinoid crisis by meta-analysis. The overall pooled risk of perioperative carcinoid crisis was similar despite the prophylactic administration of SSTA (OR 0.44, 95% CI: 0.14 to 1.35, p=0.15).

CONCLUSIONS

SSTA was not helpful for preventing carcinoid crisis based on a meta-analysis of retrospective studies. Attentive monitoring and careful intervention are essential. Future studies with better quality are needed to clarify any effect of SSTA for preventing carcinoid crisis.

[Relationship between serum histamine levels and ST-segment resolution in patients with acute myocardial infarction treated with primary percutaneous coronary intervention]

OBJECTIVE

To investigate the dynamic changes in serum histamine levels and their association with ST-segment resolution in patients with acute ST-segment elevation myocardial infarction (STEMI) treated with primary percutaneous coronary intervention (PCI).

METHODS

A total of 84 consecutive STEMI patients who received primary PCI were enrolled in this study. The dynamic changes in serum histamine levels were observed from before PCI to 1 week after PCI. Factors associated with ST-segment resolution were identified by multivariate regression analysis.

RESULTS

The serum histamine levels of STEMI patients decreased during the first week after PCI. Multivariate regression analysis showed that the factors associated with ST-segment resolution 2 h after PCI were: the histamine level 2 h after PCI (r=-0.361, P=0.001), pain to balloon time, infarct related artery, and thrombolysis in myocardial infarction (TIMI) flow grade after PCI.

CONCLUSION

The higher histamine level 2 h after PCI was independently associated with poor myocardial reperfusion in STEMI patients.

[Hyperkalemia-induced failure of pacemaker capture and sensing: a case report]

Hyperkalemia may induce serious cardiac arrhythmia, with possible life-threatening effects. It may cause cardiac pacemaker (PMK) malfunctioning due to a reduction of the electronegativity of the resting myocardial potential. We report the case of a 71-year-old woman who had a previous history of chronic heart failure, chronic renal failure and DDI pacemaker. She was admitted for disturbance of consciousness. During hospitalization, she was observed for extreme hypotension, acute hyperkalemia, ventricular escape rhythm, associated with failure of pacemaker capture and sensing. She was treated with calcium chloride injection, followed by insulin/glucose and sodium bicarbonate infusions; the electrocardiogram recordings showed an correction of the PMK malfunctioning and serial improvement of the intraventricular conduction. This case supports that hyperkalemia should be closely monitored in the chronic heart failure patients combined with chronic renal failure.

[Myocardial protection of remote ischemic postconditioning during primary percutaneous coronary intervention in patients with acute ST-segment elevation myocardial infarction]

OBJECTIVE

To evaluate the cardioprotection of remote ischemic postconditioning (RIPostC) in patients with acute ST-segment elevation myocardial infarction (STEMI) who underwent primary percutaneous coronary intervention (PCI).

METHODS

Forty-six STEMI patients undergoing primary PCI at Peking University Third Hospital from January to April 2014 were randomized to RIPostC group (n=23) and control group (n=23).The RIPostC protocol was started within 1 min after reflow by thrombus aspiration or balloon inflation and consisted of 3 cycles of 5 min/5 min ischemia/reperfusion by cuff inflation/deflation of the lower left limb. The enzymatic infarct size, rate of complete ST segment resolution, corrected thrombolysis in myocardial infarction (TIMI) frame count (CTFC) in infarct-related artery (IRA) and plasma levels of malondialdehyde(MDA), endothelin-1(ET-1), tumor necrosis factor α (TNFα) of the two groups were compared.

RESULTS

There was no significant difference in enzymatic infarct size between the two groups (P>0.05). The rate of complete ST-segment resolution was significantly higher in RIPostC group than in control group (60.9%vs. 30.4%,P=0.04). There was a trend toward lower CTFC in RIPostC group than that in control group, but the difference was not statistically significant(28 ± 11 vs. 33 ± 11, P = 0.10). However, in the subgroup of anterior wall myocardial infarction CTFC in RIPostC group was significantly lower, compared with control group (25±9 vs. 39±10, P=0.01).There were lower plasma levels of MDA,ET-1,TNFα in RIPostC group than in control group at different time points after primary PCI (P<0.05).

CONCLUSION

In STEMI patients undergoing primary PCI, RIPostC may improve myocardial perfusion and attenuate ischemia reperfusion injury with the underlying mechanisms involving reduction of oxidative stress, protection of endothelial function and inhibition of inflammatory response.

[Establishment of a FVB/N mouse model of cardiac hypertrophy by isoprenaline]

OBJECTIVE

To investigate the condition of isoprenaline (ISO)-induced cardiac hypertrophy in the FVB/N mouse.

METHODS

ISO (30 mg/kg/d) was administered either by daily subcutaneous injection, or by continuous infusion via an implanted osmotic minipump. The mice in each mode of administration were randomly divided into two groups. For subcutaneous injection: the mice received ISO or saline through daily subcutaneous injection for 2 weeks. The mice for minipump: the mice received continuous infusion of ISO via an implanted osmotic minipump for 2 weeks, or received sham operation as the control to mimipump. The ratio of heart weight to tibia length (HW/TI), the diastolic left ventricular posterior wall thickness (dLVPW) were used to indicate cardiac hypertrophy. Interstitial fibrosis was examined with picrosirius red staining.

RESULTS

ISO (30 mg/kg/d) administered by daily subcutaneous injection did not lead to cardiac hypertrophy or fibrosis in the FVB/N mice, and 50% of the mice died before the end point. The mice receiving ISO via minipumps showed significant increase in HW/TI [(10.60±0.40 ) mg/mm vs. (7.93±0.19) mg/mm,P<0.001] and dLVPW [(0.87±0.03) mm vs. (0.68±0.06)mm,P=0.0116]. ISO administered via minipumps did not induce cardiac fibrosis. All the mice in this group survived to the end point.

CONCLUSION

ISO (30 mg/kg/d) administered by continuous infusion via a minipump for 2 weeks can lead to significant cardiac hypertrophy.

A study on dysbaric osteonecrosis in caisson workers

PURPOSE

To study the effects of exposure to compressed air on tunnel workers' health and to investigate the prevalence of dysbaric osteonecrosis (DON) in caisson workers.

METHODS

128 tunnel workers were divided into the exposed group (n = 58) and the control group (n = 70), and their shoulders, hips and knees were examined with X-ray, computed tomography (CT) and magnetic resonance imaging (MRI).

RESULTS

1) 34.5% of the exposed group were diagnosed with DON based on the national diagnostic criteria of decompression sickness. 2) The incidental difference of skeletal cystic changes between the exposed group and the control group was highly statistically significant (p < 0.01). 3) CT and MRI examination could detect early onset of DON lesions, and the cystic changes shown in CT and abnormal signals in MRI were diagnostic indicators in cases.

CONCLUSION

Cystic changes in CT and abnormal signals in MRI are key imaging findings of early DON.

Characterization of a broadband all-optical ultrasound transducer-from optical and acoustical properties to imaging

A broadband all-optical ultrasound transducer has been designed, fabricated, and evaluated for high- frequency ultrasound imaging. The device consists of a 2-D gold nanostructure imprinted on top of a glass substrate, followed by a 3 microm PDMS layer and a 30 nm gold layer. A laser pulse at the resonance wavelength of the gold nanostructure is focused onto the surface for ultrasound generation, while the gold nanostructure, together with the 30 nm thick gold layer and the PDMS layer in between, forms an etalon for ultrasound detection, which uses a CW laser at a wavelength far from resonance as the probing beam. The center frequency of a pulse-echo signal recorded in the far field of the transducer is 40 MHz with -6 dB bandwidth of 57 MHz. The signal to noise ratio (SNR) from a 70 microm diameter transmit element combined with a 20 microm diameter receive element probing a near perfect reflector positioned 1.5 mm from the transducer surface is more than 10 dB and has the potential to be improved by at least another 40 dB. A high-frequency ultrasound array has been emulated using multiple measurements from the transducer while mechanically scanning an imaging target. Characterization of the device's optical and acoustical properties, as well as preliminary imaging results, strongly suggest that all-optical ultrasound transducers can be used to build high-frequency arrays for real-time high-resolution ultrasound imaging.

Optoacoustic generation of high frequency sound for 3-D ultrasonic imaging in medicine

The most common form of optoacoustic generation is thermoelasticity. Thermoelastic transduction is easy to implement and can be very broadband. However, its major drawback has always been poor conversion efficiency when a metallic film is used as the transducer. We have investigated two alternate structures for high efficiency, one based on a thin polymer film and the other using a two-dimensional nanostructure.

Cyclosporine A (CsA) affects the pharmacodynamics and pharmacokinetics of the atypical antipsychotic amisulpride probably via inhibition of P-glycoprotein (P-gp)

The importance of P-glycoprotein (P-gp) in the pharmacokinetics of amisulpride and the effects of a P-gp inhibitor cyclosporine A (CsA) was investigated both, in vitro and in vivo. In vitro and in vivo results indicated amisulpride as a substrate of P-gp. Amisulpride was not metabolized by rat liver microsomes. Open field behavior showed time dependent abolishment in locomotion by amisulpride (50 mg kg(-1)). Co-administration of CsA (50 mg kg(-1)) resulted in a higher and significantly longer antipsychotic effect (24 h after drug administration). Accordingly, the area under concentration-time curve in serum and brain was higher in CsA co-treated rats (13.5 vs. 29.8 micromol h l(-1) for serum and 2.16 vs 2.98 micromol h l(-1) for brain tissue) while renal clearance was not affected. These results pointed to a pharmacokinetic drug interaction between CsA and amisulpride most likely caused by inhibition of P-gp.

Room-Temperature, Low-Pressure Nanoimprinting Based on Cationic Photopolymerization of Novel Epoxysilicone Monomers

A new UV-curable liquid resist based on cationic polymerization of silicone epoxies has been developed for UV-assisted nanoimprint lithography. Uniform films with thicknesses ranging from below 50 nm to over 1 μm can be easily spin-coated using a suitable undercoating layer on a substrate. Patterns with feature sizes ranging from tens of micrometers to 20 nm are imprinted at room temperature with a pressure of less than 0.1 MPa.

Membrane-type matrix metalloproteinase-1 (MT1-MMP) is down-regulated in estrogen-deficient rat osteoblast in vivo

Our previous study showed that estrogen stimulates membrane-type matrix metalloproteinases-1 (MT1-MMP) production in osteoblastic cells culture, but has no effect on MMP-2 and TIMP-2 synthesis. Osteoblast-derived MT1-MMP have been recently implied to play a role in bone metabolism by degrading tumor necrosis factor-alpha (TNF-alpha), resolving extracellular matrix and activating proMMP-2, which requires the process of activation mediated by MT1-MMP/tissue inhibitor of metalloproteinase (TIMP-2) complex on the cell surface. To investigate the mechanism of bone loss following estrogen deficiency, we examined the effects of estrogen on osteoblast synthesis of MT1-MMP, MMP-2 and TIMP-2. In situ hybridization and immunohistochemistry of rat bone samples were used to document the synthesis of MT1-MMP, MMP-2, and TIMP-2 mRNA and protein. Osteoblasts from distal femoral head showed an increase in the pattern of MT1-MMP mRNA and protein production in sham-operated controls and 17beta-estradiol (E2)-treated rats, compared with the ovariectomized group; the synthesis of MMP-2 and TIMP-2 mRNA and protein was unaffected. Our data show a down-regulation of MT1-MMP synthesis by osteoblast in vivo following estrogen withdrawal, and treatment with E2 resulted in induced MT1-MMP expression in vivo. There is evidence suggesting a role for MT1-MMP in the process of bone loss during the pathogenesis of osteoporosis.

Coherent electron transport in a Si quantum dot dimer

We show that the coherence of charge transfer through a weakly coupled double-dot dimer can be determined by analyzing the statistics of the conductance pattern, and does not require a large phase coherence length in the host material. We present an experimental study of the charge transport through a small Si nanostructure, which contains two quantum dots. The transport through the dimer is shown to be coherent. At the same time, one of the dots is strongly coupled to the leads, and the overall transport is dominated by inelastic cotunneling processes.

Effect of phenolic alkaloids from Menispermum dauricum on myocardial-cerebral ischemia-reperfusion injury in rabbits

AIM

To explore the mechanism underlying the effect of phenolic alkaloids from Menispermum dauricum (PAMd) on simultaneous myocardial-cerebral ischemia-reperfusion injury in rabbits.

METHODS

Both left anterior descending coronary artery and bilateral carotid arteries were occluded to induce myocardial-cerebral ischemia-reperfusion injury in rabbits. At 30 min after ischemia, the occlusion was removed and shed blood was rapidly reinfused. Two mL of blood was taken fr om femoral artery at 10 min before ischemia, 1, 10, and 30 min after ischemia, and 1, 10, 30, 60, 120, 180, and 240 min after reperfusion. Each rabbit was sacrificed at the end of reperfusion, and left ventricle, hippocampus, cortex, and cerebellum were taken out. Malondialdehyde (MDA) content and superoxide dismutase (SOD) activity were determined.

RESULTS

At 10 min after reperfusion, MDA content in serum was significantly higher and SOD activity was lower in ischemia-reperfusion (I-R) group than those of control group (P < 0.05). After administration of PAMd, MDA content was lower and SOD activity was higher in serum than those of I-R group (P < 0.05). Both MDA content and SOD activity in tissues had the similar results with those in serum.

CONCLUSION

PAMd could attenuate the injury induced by lipid peroxidation and enhance the activity of SOD, thus PAMd might play a protective role in simultaneous myocardial-cerebral ischemia-reperfusion injury.

Magnetically induced reconstruction of the ground state in a few-electron Si quantum dot

We report unexpected fluctuations in the positions of Coulomb blockade peaks at high magnetic fields in a small Si quantum dot. The fluctuations have a distinctive sawtooth pattern: as a function of magnetic field, linear shifts of peak positions are compensated by abrupt jumps in the opposite direction. The linear shifts have large slopes, suggesting formation of the ground state with a nonzero angular momentum. The value of the momentum is found to be well defined, despite the absence of the rotational symmetry in the dot.

No subacute thrombosis and femoral bleeding complications under full anticoagulation in 150 consecutive patients receiving non-heparin-coated intracoronary Palmaz-Schatz stents

Intracoronary stenting has been shown to have better immediate and long-term clinical outcomes and less restenosis than standard balloon angioplasty. However, the benefit was achieved at the cost of higher rates of coronary thrombosis, bleeding complications, the need for anticoagulation, and longer hospital stay. For the latter reasons there is a tendency to replace the anticoagulants by antiplatelet agents alone after stenting. However, we prospectively monitored 150 consecutive patients (133 men, 17 women, mean age 58.5 years) from two centers since February 1993. They all had coronary artery disease and underwent percutaneous implantation of non-heparin-coated Palmaz-Schatz coronary stents under a full but lower dose of anticoagulation. The femoral approach was used in all patients except one. In the 150 patients, 200 stents were implanted in 165 target arteries with 172 lesions. Stenting was performed without the guidance of intravascular ultrasonography; high-pressure poststenting inflation was used in only 17.3% of patients with less than optimal angiographic results. Coronary angiography was performed at baseline, immediately after the procedure, and after 6 months (mean 207 +/- 53.6 days SD) of stenting. The mean (+/-SD) coronary minimum luminal diameter increased from 0.52 0.31 mm to 3.13 +/- 0.42 mm immediately after stenting was performed and was 2.12 +/- 0.91 mm at 6 months. There was a 0% subacute thrombosis rate and a 0% femoral bleeding complication rate in the whole series. Only three (2%) major events occurred: one Q-wave myocardial infarction from closure of an angioplasty site distal to the stent on a very long lesion, one cerebrovascular accident, and one noncoronary-related death. The only patient who underwent the brachial approach had hematoma; otherwise no other minor event occurred. The mean hospital stay was 4.5 days in one of the two study centers. The long-term clinical follow-up rate was 97.3%. The mean (+/- SD) clinical follow-up period was 589 +/- 363 days. Clinical symptoms improved; the percentage of patients who had angina according to the Canadian Cardiovascular Society functional class II, III, and IV was 31.3%, 44.7%, and 4%, respectively, before stenting was performed and was reduced to 4.7%, 3.7%, and 0%, respectively at 6-month follow-up after stenting was performed. The 6-month angiographic restudy rate was 90.6%, and the restenosis rate was 18.3%. In contrast to other reported series, these results support the idea that with careful puncture technique and meticulous postoperative wound care, intracoronary stenting can be successfully performed with the patient under full anticoagulation without major risks of bleeding and femoral vascular complications. Furthermore with a full but comparatively lower dose of anticoagulation, subacute thrombotic complications can be reduced to 0% even with non-heparin-coated stents without the use of intravascular ultrasound guidance and without the use of adjunctive high-pressure poststenting inflation in most patients. The restenosis rate and long-term clinical outcomes remained very favorable.

[A study on the change of myocardial neuropeptide Y release induced by electric stimulation and myocardial ischemia in guinea pig heart]

Electrical stimulation of the left stellate ganglion in guinea pig heart evoked a calcium-dependent, exocytotic release of neuropeptide Y (NPY). Stimulation after 10 min of global ischemia (S2), compared with control period stimulation (S1), had no significant effect on the NPY release. The release of NPY produced by the same stimulation after 20 min of ischemia was inhibited to certain extent (S2/S1: 0.72, P < 0.05), whereas the inhibition of NPY release disappeared after 5 min of reperfusion (with a S2/S1 of 1.01). Ischemia alone, without electric stimulation, did not apparently induce NPY release, suggesting that electrical stimulation may induce a calcium-dependent, exocytotic release of NPY. It is further suggested that the inhibition of NPY release may be produced by some metabolites and the abolishment of the inhibition after reperfusion may be due to washout of the metabolites.

Serotonin outflow in the hypothalamus of conscious rats: origin and possible involvement in cardiovascular control

The push-pull technique was used to investigate the effects of neuroactive compounds and experimentally induced blood pressure changes on the release of endogenous serotonin in the posterior hypothalamic area of the rat. Hypothalamic superfusion with artificial cerebrospinal fluid which contained 80 mM K+ or 1 microM veratridine enhanced the rate of serotonin release. Superfusion with tetrodotoxin (5 microM) led to a pronounced decrease in the serotonin release rate. Increases in blood pressure elicited by intravenous infusions of noradrenaline (3-4 micro g/kg/min) or phenylephrine (10 microg/kg/min) enhanced the release of serotonin in the hypothalamus. Similarly, the serotonin release rate was enhanced by hypervolaemia. Decreases in blood pressure elicited by intravenous administration of nitroprusside (30-40 microg/kg/min) or chlorisondamine (3 mg/kg) reduced the release of serotonin. Likewise, the serotonin release rate was decreased by hypovolaemia. With one exception (hypothalamic superfusion with tetrodotoxin) neither neuroactive drugs, nor experimentally elicited blood pressure changes modified the release rate of the metabolite 5-hydroxyindoleacetic acid (5-HIAA). These findings show that changes in blood pressure lead to counteractive alterations in the release of serotonin. Thus, serotoninergic neurons of the posterior hypothalamus seem to be involved in the homeostasis of blood pressure by exerting a hypotensive function. At least in the hypothalamus, the concentration of 5-HIAA in the superfusate does not seem to be a reliable marker for the activity of serotoninergic neurons.

Ionic and haemodynamic changes influence the release of the excitatory amino acid glutamate in the posterior hypothalamus

The push-pull technique was used to investigate the release of the excitatory amino acid glutamate in the posterior hypothalamic area of the conscious rat. The hypothalamus was superfused through the push-pull cannula with artificial cerebrospinal fluid (CSF), and the superfusate was collected in time periods of 10 min when ionic conditions in the CSF were changed, or in short periods of 3 min when blood pressure changes were evoked. The mean glutamate release rate was 2.8 +/- 0.7 pmol/min. Depolarization by hypothalamic superfusion with CSF containing 50 mM K+ enhanced the release of glutamate in the presence of Ca2+. The K(+)-induced release was attenuated by 40% when the hypothalamus was superfused with Ca(2+)-free CSF. Replacement of Ca2+ by Mg2+ abolished the K(+)-induced release of glutamate. Hypovolaemia elicited by haemorrhage enhanced the release rate of glutamate. Similarly, a hypotension elicited by i.v. injection of chlorisondamine (3 mg/kg) led to a pronounced and permanent enhancement in glutamate release. The effects of hypovolaemia and chlorisondamine on glutamate release were abolished in aortic denervated rats, indicating that this response is due to a decrease of impulse generation in baroreceptors. A hypervolaemia elicited by blood infusion did not affect the release of glutamate. Similarly, a pronounced pressor response to phenylephrine (15 micrograms/kg per minute) infused intravenously for 9 min was ineffective. The results show that the K(+)-induced release of glutamate in the hypothalamus is dependent on the presence of Ca2+. The increase in glutamate release rate by hypovolaemia or chlorisondamine suggests that the glutamatergic neurons in the posterior hypothalamic area respond to unloading of aortic baroreceptors and possess a counteracting, hypertensive function.

Effects of hemodynamic changes on taurine release from posterior hypothalamus of freely moving rats

AIM

To study the effects of blood volume and vascular resistance on taurine release.

METHODS

We used push-pull superfusion technique in the posterior hypothalamus of conscious freely moving rats. Taurine was determined in the superfusate by HPLC with fluorescence detection following automatic precolumn o-phthaldialdehyde (OPA) derivatization.

RESULTS

Hypervolemia increased the release of taurine in the hypothalamus. Intravenous infusion of levarterenol (3 micrograms kg-1 min-1) elicited a pronounced pressor response and an increase in the release of taurine. Conversely, a controlled hemorrhagic hypotension or iv infusion of nitroprusside (30 micrograms kg-1 min-1) elicited a hypotension and a decrease in the release of taurine from the posterior hypothalamus.

CONCLUSION

In the posterior hypothalamus, taurine might play an important role in central blood pressure regulation.

Taurine release in the hypothalamus is altered by blood pressure changes and neuroactive drugs

The release of endogenous taurine was determined in the posterior hypothalamus of the conscious, freely moving rat by using the push-pull superfusion technique. At the start of superfusion, the outflow of endogenous taurine declined rapidly with a half-time of 7.9 min and reached a steady state after approximately 1 h. Thereafter, the release rate was constant and amounted to 2.6 +/- 0.3 pmol/min. During depolarization either with K+ (50 or 90 mM) or veratridine (1 or 10 microM), taurine outflow was increased in a concentration-dependent way. Hypothalamic superfusion with tetrodotoxin (1 microM) elicited a sustained decrease in the taurine release to 60% of the control values. Intravenous infusion of noradrenaline led to a rise in blood pressure (45 mm Hg) and enhanced the release of taurine in the hypothalamus. A fall of blood pressure (30 mm Hg) caused by an intravenous infusion of nitroprusside diminished taurine outflow. The results suggest that a considerable amount of the taurine detected is released from hypothalamic neurons. Changes in the release rate of taurine by experimentally induced alterations of blood pressure indicate that, in the posterior hypothalamus, the amino acid might play an important role as a neurotransmitter or neuromodulator possessing a hypotensive function.