Enhancing cancer therapy: The role of drug delivery systems in STAT3 inhibitor efficacy and safety

The signal transducer and activator of transcription 3 (STAT3), a member of the STAT family, resides in the nucleus to regulate genes essential for vital cellular functions, including survival, proliferation, self-renewal, angiogenesis, and immune response. However, continuous STAT3 activation in tumor cells promotes their initiation, progression, and metastasis, rendering STAT3 pathway inhibitors a promising avenue for cancer therapy. Nonetheless, these inhibitors frequently encounter challenges such as cytotoxicity and suboptimal biocompatibility in clinical trials. A viable strategy to mitigate these issues involves delivering STAT3 inhibitors via drug delivery systems (DDSs). This review delineates the regulatory mechanisms of the STAT3 signaling pathway and its association with cancer. It offers a comprehensive overview of the current application of DDSs for anti-STAT3 inhibitors and investigates the role of DDSs in cancer treatment. The conclusion posits that DDSs for anti-STAT3 inhibitors exhibit enhanced efficacy and reduced adverse effects in tumor therapy compared to anti-STAT3 inhibitors alone. This paper aims to provide an outline of the ongoing research and future prospects of DDSs for STAT3 inhibitors. Additionally, it presents our insights on the merits and future outlook of DDSs in cancer treatment.

Seizing the fate of lymph nodes in immunotherapy: To preserve or not?

Lymph node dissection has been a long-standing diagnostic and therapeutic strategy for metastatic cancers. However, questions over myriad related complications and survival outcomes are continuously debated. Immunotherapy, particularly neoadjuvant immunotherapy, has revolutionized the conventional paradigm of cancer treatment, yet has benefited only a fraction of patients. Emerging evidence has unveiled the role of lymph nodes as pivotal responders to immunotherapy, whose absence may contribute to drastic impairment in treatment efficacy, again posing challenges over excessive lymph node dissection. Hence, centering around this theme, we concentrate on the mechanisms of immune activation in lymph nodes and provide an overview of minimally invasive lymph node metastasis diagnosis, current best practices for activating lymph nodes, and the prognostic outcomes of omitting lymph node dissection. In particular, we discuss the potential for future comprehensive cancer treatment with effective activation of immunotherapy driven by lymph node preservation and highlight the challenges ahead to achieve this goal.

Nanoparticles Targeting Lymph Nodes for Cancer Immunotherapy: Strategies and Influencing Factors

Immunotherapy has emerged as a potent strategy in cancer treatment, with many approved drugs and modalities in the development stages. Despite its promise, immunotherapy is not without its limitations, including side effects and suboptimal efficacy. Using nanoparticles (NPs) as delivery vehicles to target immunotherapy to lymph nodes (LNs) can improve the efficacy of immunotherapy drugs and reduce side effects in patients. In this context, this paper reviews the development of LN-targeted immunotherapeutic NP strategies, the mechanisms of NP transport during LN targeting, and their related biosafety risks. NP targeting of LNs involves either passive targeting, influenced by NP physical properties, or active targeting, facilitated by affinity ligands on NP surfaces, while alternative methods, such as intranodal injection and high endothelial venule (HEV) targeting, have uncertain clinical applicability and require further research and validation. LN targeting of NPs for immunotherapy can reduce side effects and increase biocompatibility, but risks such as toxicity, organ accumulation, and oxidative stress remain, although strategies such as biodegradable biomacromolecules, polyethylene glycol (PEG) coating, and impurity addition can mitigate these risks. Additionally, this work concludes with a future-oriented discussion, offering critical insights into the field.

[Prognostic value of the Second Revision of the International Staging System in patients with newly diagnosed transplant-eligible multiple myeloma]

Objective: To verify the predictive value of the Second Revision of the International Staging System (R2-ISS) in newly diagnosed patients with multiple myeloma (MM) who underwent first-line autologous hematopoietic stem cell transplantation (ASCT) in a new drug era in China. Methods: This multicenter retrospective cohort study enrolled patients with newly diagnosed MM from three centers in China (Beijing Chao-Yang Hospital, Capital Medical University; the First Affiliated Hospital, Sun Yat-Sen University, and the Second Affiliated Hospital of Naval Medical University) from June 2008 to June 2018. A total of 401 newly diagnosed patients with MM who were candidates for ASCT were enrolled in this cohort, all received proteasome inhibitor and/or immunomodulator-based induction chemotherapy followed by ASCT. Baseline and follow-up data were collected. The patients were regrouped using R2-ISS. Progression-free survival (PFS) and overall survival (OS) were analyzed. The Kaplan-Meier method was used to analyze the survival curve and two survival curves were compared using the log-rank test. Cox regression analysis were performed to analyze the relationship between risk factors and survival. Results: The median age of the patients was 53 years (range 25-69 years) and 59.5% (240 cases) were men. Newly diagnosed patients with renal impairment accounted for 11.5% (46 cases). According to Revised-International Staging System (R-ISS), 74 patients (18.5 %) were diagnosed with stage Ⅰ, 259 patients (64.6%) with stage Ⅱ, and 68 patients (17.0%) with stage Ⅲ. According to the R2-ISS, the distribution of patients in each group was as follows: 50 patients (12.5%) in stage Ⅰ, 95 patients (23.7%) in stage Ⅱ, 206 patients (51.4%) in stage Ⅲ, and 50 patients (12.5%) in stage Ⅳ. The median follow-up time was 35.9 months (range, 6-119 months). According to the R2-ISS stage, the median PFS in each group was: 75.3 months for stage Ⅰ; 62.0 months for stage Ⅱ, 39.2 months for stage Ⅲ, and 30.3 months for stage Ⅳ; and the median OS was not reached, 86.6 months, 71.6 months, and 38.5 months, respectively. There were statistically significant differences in PFS and OS between different groups (both P<0.001). Multivariate Cox regression analysis showed that stages Ⅲ and Ⅳ of the R2-ISS were independent prognostic factors for PFS (HR=2.37, 95%CI 1.30-4.30; HR=4.50, 95%CI 2.35-9.01) and OS (HR=4.20, 95%CI 1.50-11.80; HR=9.53, 95%CI 3.21-28.29). Conclusions: The R2-ISS has significant predictive value for PFS and OS for transplant-eligible patients with MM in the new drug era. However, the universality of the R2-ISS still needs to be further verified in different populations.

[Resveratrol attenuates cardiac function impairment in plateau hypobaric hypoxia rats]

Objective: To study the protective effects of resveratrol (RSV) on cardiac function in rats with high altitude hypobaric hypoxia and its mechanisms. Methods: Thirty-six rats were randomly divided into control group, hypobaric hypoxia group (HH) and hypobaric hypoxia + RSV group (HH+RSV) according to the random number, 12 rats in each group. Rats in the HH and HH+RSV groups were subjected to chronic long-term high altitude hypobaric hypoxia intervention for 8 weeks in a hypobaric chamber at a simulated altitude of 6 000 m for 20 h / d. The rats of HH + RSV were fed with RSV at a dose of 400 mg/(kg·d). The rats were tested once a week for body weight and twice a week for food intake. Before execution, the rats were tested by blood cell analyzer for routine blood parameters and echocardiogram for cardiac function parameters in each group. The routine blood indexes of each group were measured by blood cell analyzer, the cardiac function indexes of each group were measured by echocardiography, myocardial hypertrophy was evaluated by HE staining, myocardial tissue reactive oxygen levels were evaluated by dihydroethidium (DHE) staining. Oxidative stress was evaluated by serum and myocardial tissue total antioxidant capacity (T-AOC), superoxide dismutase activity (SOD) and malondialdehyde (MDA) content. Results: Compared with the C group, the body mass and food intake of rats were decreased significantly (P＜0.05) in HH group, while compared with the C group, RSV had no significant effects on the body mass and food intake of rats in the HH+RSV group (P＞0.05). Compared with the C group, the levels of erythrocytes and hemoglobin of rats in the HH group were increased significantly (P＜0.05), while the platelet concentration was decreased significantly(P＜0.05); compared with the HH group, the erythrocyte and hemoglobin levels were decreased significantly (P＜0.05) and platelet concentration was increased significantly(P＜0.05) in rats of the HH+RSV group. Compared with the C group, the cardiac coefficient, myocardial fiber diameter and thickness were significantly increased in the HH group (P＜0.05); compared with the HH group, the cardiac coefficient and myocardial fiber thickness were significantly decreased in the HH+RSV group (P＜0.05). Echocardiographic analysis showed a significant increase in ventricular wall thickness (P＜0.05) and a significant decrease in ejection fraction and cardiac output (P＜0.05) in the HH group compared with the C group, and a significant decrease in ventricular wall thickness and a significant improvement in cardiac function (P＜0.05) in the HH+RSV group compared with the HH group. The results of DHE staining showed that myocardial tissue reactive oxygen levels were increased significantly in the HH group compared with the C group (P＜0.05); myocardial tissue reactive oxygen levels were significantly restored in the HH+RSV group compared with the HH group (P＜0.05). The oxidative/antioxidant results showed that the serum and myocardial T-AOC and SOD activities were decreased significantly (P＜0.05) and the MDA level was increased significantly (P＜0.05) in the HH group compared with the C group; the serum and myocardial T-AOC and SOD activities were increased significantly (P＜0.05) and the MDA level was decreased significantly(P＜0.05) in the HH+RSV group compared with the HH group. Conclusion: Long-term plateau hypobaric hypoxia exposure leads to myocardial hypertrophy and reduced cardiac function in rats. Resveratrol intervention significantly improves myocardial hypertrophy and cardiac function in rats caused by altitude hypobaric hypoxia exposure, which is closely related to reducing of reactive oxygen species and improving myocardial oxidative stress levels.

[The prognostic value of dynamic minimal residual disease after autologous hematopoietic stem cell transplantation in patients with multiple myeloma in novel-agent era]

Objective: To investigate the clinical prognostic value of dynamic minimal residual disease (MRD) after autologous hematopoietic stem cell transplantation (AHSCT) in patients with multiple myeloma (MM). Methods: Patients with MM who underwent AHSCT in Beijing Chao-Yang Hospital from February 2016 to December 2019 were enrolled in this study. All the patients in the study had complete baseline data at the diagnosis. AHSCT was performed after induction chemotherapy. Response evaluation was performed after induction therapy. All the patients were assessed at approximately 100 days after AHSCT. Bone marrow MRD by NGF was performed every three months and dynamically monitored for at least 12 months. All the patients were divided into different groups according to cytogenetics and MRD status. Survivals in different groups were analyzed by IBM SPSS 22.0 statistical software. Results: A total of 150 patients with MM were enrolled in this study at last, including 66 patients in the cytogenetic standard risk group and 84 patients in the cytogenetic high-risk group. The median age was 54 years (range 30-68 years) and 87 male patients (58.0%) was in the study. The median follow-up was 36 months (range 16-72 months). Patients in the standard-risk group had better clinical prognosis than those in the high-risk group [median PFS in the standard-risk group was not achieved, and median PFS in the high-risk group was 45 months (P<0.001); median OS of both groups was not reached, and the estimated 3-year OS rate of the standard-risk group and the high-risk group was 95.2% and 78.9%, respectively (P=0.001)]. According to MRD status of patients, patients in each group were divided into three subgroups: persistent positive (Ppos), transient negative (Tneg) and persistent negative (Pneg). The median OS and median PFS of all subgroups in the standard-risk group was not reached (P=0.324 and P=0.086). In high-risk group, the median OS of MRD Pneg subgroup was not reached, and the estimated 3-year OS rate was 100%; The median OS of MRD Ppos subgroup was 52 months, and MRD Tneg subgroup only 31 months (P=0.002); the median PFS of MRD Pneg group was not reached, and the estimated 3-year PFS rate was 85.4%; median PFS of MRD Ppos subgroup was 40 months, and MRD Tneg subgroup only 17 months (P=0.001). Conclusions: MRD Pneg might overcome the adverse prognosis of MM patients with high-risk cytogenetics. However, MRD Tneg might be a poor prognostic factor for the patients with cytogenetic high-risk MM.

Chinese Herbal Preparation SaiLuoTong Alleviates Brain Ischemia via Nrf2 Antioxidation Pathway-Dependent Cerebral Microvascular Protection

Stroke is one of the most devastating diseases worldwide. The Chinese herbal preparation SaiLuoTong (SLT) capsule showed outstanding therapeutic effects on stroke and its sequelae. The aim of this study was to further elucidate its therapeutic mechanism. We duplicated a permanent cerebral ischemia model in rats by MCAO and used SLT (33 and 16.5 mg/kg) to intervene. The results showed SLT dose dependently decreased infarction volumes, relieved neuron degeneration and loss, and ameliorated neurological functions, and the dose of 33 mg/kg had statistical significance (compared with the model group, p < 0.05); SLT of 33 mg/kg also significantly inhibited the elevation in brain water content and the loss in claudin-1 and occludin expressions; additionally, it significantly increased nucleus translocation of Nrf2, elevated the expression of HO-1, and raised the activity of SOD and content of GSH (compared with the model group, p < 0.05 or 0.01). These results testified SLT’s anti-brain ischemia effect and hint this effect may be related to the protection of brain microvascular endothelial cells (BMECs) that is dependent on the Nrf2 pathway. To further testify, we cultured hCMEC/D3 cells, duplicated OGD/R model to simulate ischemia, and used SLT (3.125, 6.25, and 12.5 mg/L) to treat. SLT dose dependently and significantly inhibited the drop in cell viabilities, and activated the Nrf2 pathway by facilitating Nrf2 nucleus translocation, and increasing HO-1 expression, SOD activity, and GSH content (compared with the model group, p < 0.05 or 0.01); last, the anti-OGD/R effects of SLT, including raising cell viabilities, inhibiting the elevation in dextran permeability, and preserving expressions of claudin-1 and occludin, were all abolished by Nrf2 siRNA interference. The in vitro experiment undoubtedly confirmed the direct protective effect of SLT on BMECs and the obligatory role of the Nrf2 pathway in it. Collectively, data of this study suggest that SLT’s therapeutic effect on brain ischemia is related to its Nrf2-dependent BMECs protection.

Histochemistry of microinfarcts in the mouse brain after injection of fluorescent microspheres into the common carotid artery

The mouse model of multiple cerebral infarctions, established by injecting fluorescent microspheres into the common carotid artery, is a recent development in animal models of cerebral ischemia. To investigate its effectiveness, mouse models of cerebral infarction were created by injecting fluorescent microspheres, 45–53 µm in diameter, into the common carotid artery. Six hours after modeling, fluorescent microspheres were observed directly through a fluorescence stereomicroscope, both on the brain surface and in brain sections. Changes in blood vessels, neurons and glial cells associated with microinfarcts were examined using fluorescence histochemistry and immunohistochemistry. The microspheres were distributed mainly in the cerebral cortex, striatum and hippocampus ipsilateral to the side of injection. Microinfarcts were found in the brain regions where the fluorescent microspheres were present. Here the lodged microspheres induced vascular and neuronal injury and the activation of astroglia and microglia. These histopathological changes indicate that this animal model of multiple cerebral infarctions effectively simulates the changes of various cell types observed in multifocal microinfarcts. This model is an effective, additional tool to study the pathogenesis of ischemic stroke and could be used to evaluate therapeutic interventions. This study was approved by the Animal Ethics Committee of the Institute of Acupuncture and Moxibustion, China Academy of Chinese Medical Sciences (approval No. D2021-03-16-1) on March 16, 2021.

[Autologous stem cell transplantation improve the survival of newly diagnosed multiple myeloma patients]

目的

评估自体造血干细胞移植（auto-HSCT）对初治多发性骨髓瘤（MM）疗效及生存的影响。

方法

回顾性分析2008年10月1日至2019年10月1日243例65岁以下接受auto-HSCT的初治MM患者，同时以同期176例≤65岁适合移植但未进行auto-HSCT的初治MM患者作为对照，评估auto-HSCT对患者疗效及生存的影响。为平衡auto-HSCT和非auto-HSCT患者之间各因素的分布，利用倾向性评分匹配技术按照1∶1比例匹配以减少组间的偏差。

结果

通过倾向性评分匹配分析，共筛选出128例患者（每组64例）。64例患者诱导治疗后接受auto-HSCT，24例（37.5％）获得严格意义的完全缓解（sCR），16例（25.0％）获得完全缓解（CR），15例（23.4％）获得非常好的部分缓解（VGPR），9例（14.1％）获得部分缓解（PR），auto-HSCT组疗效明显优于非auto-HSCT组（P＝0.032）。与非auto-HSCT组相比，auto-HSCT组总生存（OS）和无进展生存（PFS）期明显延长［OS：87.6（95％ CI 57.3～117.9）个月对53.9（95％ CI 36.1～71.7）个月，P＝0.011；PFS：42.2（95％ CI 29.9～54.5）个月对22.4（95％ CI 17.1～27.7）个月，P＝0.007］。多因素分析显示auto-HSCT是OS（HR＝0.448，95％CI 0.260～0.771，P＝0.004）和PFS（HR＝0.446，95％CI 0.280～0.778，P＝0.003）的独立保护因素。

结论

auto-HSCT可改善适合移植初治MM患者的OS和PFS。

[The expressions and diagnostic values of miR-18a and miR-21 in esophageal cancer]

Objective: To investigate the expressional levels and diagnostic values of miR-18a and miR-21 in esophageal carcinoma. Methods: The expressions of miR-18a and miR-21 in esophageal cancer tissues and adjacent tissues from 45 esophageal cancer patients, peripheral blood from 45 esophageal cancer patients and 50 healthy donors respectively were detected by RT-PCR. The expressions of miR-18a and miR-21 in normal esophageal epithelial cell HET-1A, esophageal cancer cell lines including ECA109, KYSE150 and TE1 were also detected. Chemiluminescence immunoassay was used to quantitatively detect the concentrations of carcinoembryonic antigen (CEA), squamous cell carcinoma antigen (SCC), CYRFA21-1 and TPA (tissue polypeptide antigen) in peripheral blood serum from esophageal cancer patients and healthy controls. Meanwhile, the diagnostic effects of miR-18a and miR-21 on esophageal cancer were compared with those of tumor markers in serum. Results: The expression levels of miR-18a and miR-21 in esophageal cancer cells ECA109, KYSE150 and TE1 were 1.64±0.17, 1.62±0.19, 1.46±0.12 and 20.52±1.48, 6.73±0.73, 1.43±0.19, respectively, higher than those in normal esophageal epithelial cells (both P<0.01). The expressions of miR-18a and miR-21 in esophageal cancer tissues were 32.48±28.62 and 8.67±11.98, respectively, significantly higher than those in adjacent tissues (all P<0.001). The expression levels of miR-18a and miR-21 in peripheral blood of patients with esophageal cancer were 12.66±11.92 and 9.15±8.14, respectively, significantly higher than those in the normal control group (both P<0.001). The receiver operating characteristic (ROC) curve analysis showed that the area under the curve of miR-18a and miR-21 for diagnosis of esophageal cancer were 0.948 and 0.913 5, respectively. Compared with traditional esophageal tumor markers, the expressions of miR-18a and miR-21 were more sensitive in the diagnosis of esophageal cancer. The sensitivity and accuracy of the expressions of miR-18a and miR-21 combined with traditional esophageal tumor markers in diagnosis of esophageal cancer can be further improved to 97.8% and 68.4%, respectively. Conclusion: Our study reveals that the expressions of miR-18a and miR-21 play important roles in the diagnosis of esophageal cancer and may be potentially novel biomarkers.

[Antimicrobial susceptibility and genotyping of Mycobacterium intracellulare]

Objective: To investigate the antimicrobial susceptibility and genotyping of Mycobacterium intracellulare. Methods: A total of 150 M. intracellulare isolates were collected. The susceptibility against 15 antimicrobial agents widely used for treatment of non-tuberculosis mycobacteria (NTM) infections, was tested by broth microdilution assay. Variable number of tandem repeats (VNTR) assay was also performed using the 16-loci genotyping method. Results: The drug susceptibility test revealed that clarithromycin (97.3%, 146/150), moxifloxacin (94.0%, 141/150) and amikacin (90.0%, 135/150) had the best antimicrobial activities in vitro against the M. intracellulare isolates. Secondly, 75.3%(113/150), 64.0%(96/150), 52.7%(79/150) and 8.7%(13/150) of the strains were susceptible to rifampicin, linezolid, capreomycin, and ethambutol, respectively. The MIC(50) and MIC(90) values of the 3 injectable anti-tuberculosis drugs were as follows: amikacin 4 mg/L and 16 mg/L, streptomycin 4 mg/L and 16 mg/L, capreomycin 8 mg/L and 16 mg/L. The MIC(50) and MIC(90) values of the 5 different fluoroquinolones were 0.5 mg/L and 2 mg/L for moxifloxacin , 1 mg/L and 8 mg/L for ciprofloxacin, 1 mg/L and 8ug/ml for levofloxacin, 2 mg/L and 16 mg/L for antoflolxacin, 2 mg/L and 16 mg/L for ofloxacin. The Hunter-Gaston Discriminatory Index (HGDI) value for the 16-loci VNTR typing of M. intracellulare isolates was 0.994. VNTR differentiated the 150 isolates into 21 clusters and acquired a total of 121 unique patterns. Drug resistance profile was not independently associated with cluster strains. Conclusions: Clarithromycin, moxifloxacin and amikacin had the best antimicrobial activities in vitro against M. intracellulare isolates. The 16-loci VNTR typing revealed a highly discriminatory power and drug resistance profile was not independently associated with cluster strains.

[Characterization and pathophysiological changes of cerebral infarction rat model with qi-deficiency and blood-stasis Syndrome]

This study aimed to observe the general state and changes in pathophysiological indexes of multiple cerebral infarction rat model with Qi-deficienty and Blood-stasis syndrome. Rats were randomly divided into 4 groups(with 30 in each group): the normal group, the sham group, the model group and the Yiqi Huoxue recipe group. Rats in the model group and Yiqi Huoxue group were provided with interruptable sleep deprivation for 7 days before the multiple cerebral infarction operation, and followed by another 4 weeks of sleep deprivation; rats in the Yiqi Huoxue group were intragastrically administrated with drug at a dose of 26 g·kg⁻¹, once a day for 4 weeks. The general state was observed, and the pathophysiological indexes were measured at 48 h, 2 weeks and 4 weeks after administration. The results showed that rats in the normal group and the sham group represented a good general state and behaviors, with a normal morphological structure of brain tissues; rats in the model group featured yellow fur, depression, accidie, loose stools and movement disorder, with obvious brain histomorphological damage, which became aggravated with the increase of modeling time; rats in the Yiqi Huoxue group showed release in the general state and above indexes. Compared with the sham group at three time points, rats in the model group showed decrease in body weight, exhaustive swimming time and RGB value of tongue surface image, and increase in whole blood viscosity of the shear rate under 5, 60 and 150 S⁻¹, reduction in cerebral cortex Na⁺-K⁺-ATPase, Ca²⁺-ATPase activity and contents of 5-HT, rise in TXB2 levels and decline in 6-keto-PGF1a in serum(P<0.05, P<0.01). Compared with the model group, rats in the Yiqi Huoxue group showed alleviations in the above indexes at 2 w and 4 w(P<0.05, P<0.01). The results showed that the characterization and pathophysiological indexes in the multiple cerebral infarction rat model with Qi-deficiency and blood-stasis syndrome were deteriorated; Yiqi Huoxue recipe could significantly alliviate the abnormal conditions, which suggested of the model was stable and reliable and the pathophysiologic evolutionary mechanism might be related to energy metabolism dysfunction, vasoactive substance abnormality and changes in neurotransmitters.

A TRPA1 channel that senses thermal stimulus and irritating chemicals in Helicoverpa armigera

Sensing and responding to changes in the external environment is important for insect survival. Transient receptor potential (TRP) channels are crucial for various sensory modalities including olfaction, vision, hearing, thermosensation and mechanosensation. Here, we identified and characterized a transient receptor potential gene named as HarmTRPA1 in Helicoverpa armigera antennae. HarmTRPA1 was abundantly expressed in the antennae and labial palps. Transcripts of HarmTRPA1 could also be detected in the head and proboscis. Furthermore, functional analyses of HarmTRPA1 were conducted in the Xenopus Oocyte system. The results showed that the HarmTRPA1 channel could be activated by increasing the temperature from 20 to 45 °C. No significant adaptation was observed when the stimulus was repeated. In addition to thermal stimuli, pungent natural compounds including allyl isothiocyanate, cinnamaldehyde and citronellal also activated HarmTRPA1. Taken together, we infer that HarmTRPA1 may function as both a thermal sensor involved in peripheral temperature detection and as a chemical sensor detecting irritating chemicals in vivo. Our data provide valuable insight into the TRPA1 channel in this moth and lay the foundation for developing novel strategies for pest control.

There can be turbulence in microfluidics at low Reynolds number

Turbulence is commonly viewed as a type of macroflow, where the Reynolds number (Re) has to be sufficiently high. In microfluidics, when Re is below or on the order of 1 and fast mixing is required, so far only chaotic flow has been reported to enhance mixing based on previous publications since turbulence is believed not to be possible to generate in such a low Re microflow. There is even a lack of velocimeter that can measure turbulence in microchannels. In this work, we report a direct observation of the existence of turbulence in microfluidics with Re on the order of 1 in a pressure driven flow under electrokinetic forcing using a novel velocimeter having ultrahigh spatiotemporal resolution. The work could provide a new method to control flow and transport phenomena in lab-on-a-chip and a new perspective on turbulence.

An odorant receptor from the common cutworm (Spodoptera litura) exclusively tuned to the important plant volatile cis-3-hexenyl acetate

Olfaction plays an important role in insect behaviours. The odorant receptor (OR) repertoire, housed within the dendritic membrane of sensory neurons, is one of the primary determinants of odour recognition. ORs in moths could be classified into pheromone receptors (PRs) and non-pheromone receptors (non-PR ORs). Much research in the field of insect olfaction recently has been focused on PRs of the male moth, but few Lepidoptera studies have been done on the functional study of non-PR ORs. In the present study, we identified and characterized four non-PR ORs from Spodoptera litura (Lepidoptera: Noctuidae) antennae. The tissue expression pattern showed that the four ORs were mainly expressed in adult antennae and further in situ hybridization revealed SlituOR12 was expressed in both long and short sensilla trichodea and sensilla basiconica. A functional analysis of the four SlituORs was conducted in the heterologous expression system Xenopus oocytes. SlituOR12 was exclusively and sensitively tuned to cis-3-Hexenyl acetate and SlituOR19 slightly responded to 4'-Ethylacetophenone; however, SlituOR44 and SlituOR51 did not respond to any chemicals tested in this study. It is proposed that SlituOR12 might partially account for some key behaviours of the female, such as detection of host location and oviposition site.

[Effect of sailuotong capsule on Glu and GABA levels as well as NMDA receptor subtypes expression in recovery period of rat multiple cerebral infarction]

The rat model of multi-infarct was adopted in this study to elucidate the protective mechanism of Sailuotong capsule (Sailuotong) in recovery period of multiple cerebral infarction. The effects of Sailuotong on levels of Glu, GABA and the expression of NMDA receptor subtypes including NR1, NR2A and NR2B, were detected. The multi-infarct model rats were established by injecting embolizing microsphere via internal carotid artery, and were given Sailuotong treatment (16.5 and 33.0 mg x kg(-1)) for 60 days. The pathological changes in brain ultrastructure were observed by transmission electron microscope. The levels of Glu and GABA in brain tissue were measured with high performance liquid chromatography. The expression of NMDA receptors including NR1, NR2A and NR2B in neurons was evaluated by immunohistochemical staining. Compared with the sham rats, abnormal changes were observed in ultrastructures of neurons, neuroglia cells and synapses of model rat brains. Moreover, significant decrease of Glu and GABA, as well as the elevated expression of NR1, NR2A and NR2B were detected in brain tissues. Sailuotong (16.5 and 33.0 mg x kg(-1)) could improve ultrastructure of cerebral tissue, facilitate synthesis of Glu and GABA, and down-regulate expression of NR1, NR2A and NR2B in neurons. The results demonstrated that Sailuotong could exert neuroprotective effects to some extent in the recovery phase of multiple cerebral infarction by promoting expression of NMDA receptors and synthesis of Glu and GABA.

Laser induced fluorescence photobleaching anemometer for microfluidic devices

We have developed a novel, non-intrusive fluid velocity measurement method based on photobleaching of a fluorescent dye for microfluidic devices. The residence time of the fluorescent dye in a laser beam depends on the flow velocity and approximately corresponds to the decaying time of the photobleaching of the dye in the laser beam. The residence time is inversely proportional to the flow velocity. The fluorescence intensity increases with the flow velocity due to the decrease of the residence time. A calibration curve between fluorescence intensity and known flow velocity should be obtained first. The calibration relationship is then used to calculate the flow velocity directly from the measured fluorescence intensity signal. The new method can measure the velocity very quickly and is easy to use. It is demonstrated for both pressure driven flow and electroosmotic flow.

Regularity of distribution of immunoreactive pulmonary surfactant protein A in rat tissues

Existing data has shown that SP-A-like protein or mRNA is widely distributed in lamellar bodies such as tissues and mucosal surfaces. Using immunohistochemistry method with a polyclonal antibody against human SP-A, in this study we investigated distribution of immunoreactive pulmonary surfactant protein A (IR-SP-A) in a number of rat tissues. The SP-A-like immunoreactivity was found in alveolar, parenchyma, pleura of lung; myelin sheath of brain; epithelia of Bowman's capsule, glomerulus and renal tubules of kidney; epithelia of colon, stomach, duct of salivary gland, pharynx; and blood vessel wall and connective tissue of extracellular matrix. The positive signal was blocked by pre-absorbed SP-A antigen from recombinant or bronchoalveolar lavage (BAL). SP-A has long been considered as an important frontier host defense molecule which participates in immune and inflammatory regulation of lung. With every inhalation, small particles, viruses, bacteria, and antigens from environment are continuously deposited onto the vast pulmonary epithelial surface. While a proper host defense is required to protect the lung, an over-exuberant response can disrupt the appropriate balance between pro- and anti-inflammatory. Traditional Chinese medicine believes that body is an open system relevant to the external environment. The physical, chemical and biological environmental factors constantly affect the open system, and the body properly reacts to maintain homeostasis of body machinery. The Chinese traditional medicine scholars have thus hypothesized that 'Qi' (meaning air) is the communication way between the body and external environment. What is 'Qi'? The results from our study suggest that IR-SP-A is a candidate of 'Qi'. It is compatible with the sites, theoretically containing collagenous and lectin domain molecules, also compatible with the primary injury sites of some autoimmune diseases. SP-A may be as one of 'Qi' molecules mentioned in traditional Chinese medicine that trigger some of autoimmune diseases.

New regulatory gene that contributes to control of Bacteroides thetaiotaomicron starch utilization genes

Bacteroides thetaiotaomicron uses starch as a source of carbon and energy. Early steps in the pathway of starch utilization, such as starch binding and starch hydrolysis, are encoded by sus genes, which have been characterized previously. The sus structural genes are expressed only if cells are grown in medium containing maltose or higher oligomers of glucose. Regulation of the sus structural genes is mediated by SusR, an activator that is encoded by a gene located next to the sus structural genes. A strain with a disruption in susR cannot grow on starch but can still grow on maltose and maltotriose. A search for transposon-generated mutants that could not grow on maltose and maltotriose unexpectedly located a gene, designated malR, which regulates expression of an alpha-glucosidase not controlled by SusR. Although a disruption in susR did not affect expression of the malR controlled gene, a disruption in malR reduced expression of the sus structural genes. Thus, MalR appears to participate with SusR in regulation of the sus genes. Results of transcriptional fusion assays and reverse transcription-PCR experiments showed that malR is expressed constitutively. Moreover, multiple copies of malR provided on a plasmid (5 to 10 copies per cell) more than doubled the amount of alpha-glucosidase activity in cell extracts. Our results demonstrate that the starch utilization system of B. thetaiotaomicron is controlled on at least two levels by the regulatory proteins SusR and MalR.

Production of two proteins encoded by the Bacteroides mobilizable transposon NBU1 correlates with time-dependent accumulation of the excised NBu1 circular form

NBU1 is a mobilizable transposon that excises from the Bacteroides chromosome to form a double-stranded circular transfer intermediate. Excision is triggered by exposure of the bacteria to tetracycline. Accordingly, we expected that the expression of NBU1 genes would be induced by tetracycline. To test this hypothesis, antibodies that recognized two NBU1-encoded proteins, PrmN1 and MobN1, were used to monitor production of these proteins. PrmN1 is essential for excision, and MobN1 is essential for transfer of the excised circular form. At first, expression of the genes encoding these two proteins appeared to be regulated by tetracycline, because the proteins were detectable on Western blots only after the cells were exposed to tetracycline. However, when the prmN1 gene and/or the mobN1 gene was cloned on a multicopy plasmid, production of the protein was constitutive. Initially, we assumed that the constitutive expression was due to loss of a repressor protein that was encoded by one of the other genes on NBU1. Deletions or insertions in the other genes (orf2 and orf3) on NBU1 and various integrated NBU1 derivatives abolished production of PrmN1 and MobN1. This is the opposite of what should have happened if one or both of these genes encoded a repressor. A second possibility was that when NBU1 excised, it replicated transiently, increasing the gene dosage of prmN1 and mobN1 and thereby producing enough PrmN1 and MobN1 for these proteins to become detectable. In fact, after the cells entered late exponential phase the copy number of NBU1 increased to 2 to 3 copies per cell. Production of PrmN1 and MobN1 showed a similar pattern. Any mutation in NBU1 that decreased or prevented excision also prevented elevated production of these two proteins. Our results show that the apparent tetracycline dependence of the production of PrmN1 and MobN1 is due to a growth phase- or time-dependent increase in the number of copies of the NBU1 circular form.

Remodeling of the zero-stress state of femoral arteries in response to flow overload

The goal of this study is to quantitatively describe the remodeling of the zero-stress state of the femoral artery in flow overload. Increased blood flow, approximately as a unit step change, was imposed on the femoral artery by making an arteriovenous (a-v) fistula with the epigastric vein. The a-v fistula was created in the right leg of 36 rats, which were divided equally into six groups (2 days and 1, 2, 4, 8, and 12 wk after the fistula). The vessels in the left leg were used as controls without operative trauma. The in vivo blood pressure, flow, and femoral outer diameter and the in vitro zero-stress state geometry were measured. The in vivo shear rate at the endothelial surface increased approximately as a step function by approximately 83%, after 2 days, compared with the control artery. The arterial luminal and wall area significantly increased postsurgically from 0.15 +/- 0.02 and 0.22 +/- 0.02 mm(2) to 0.28 +/- 0.04 and 0.31 +/- 0.05 mm(2), respectively, after 12 wk. The wall thickness did not change significantly over time (P > 0.1). The opening angle decreased to 82 +/- 4.2 degrees postsurgically when compared with controls (102 +/- 4.4) after 12 wk and correlated linearly with the thickness-to-radius ratio. Histological analysis revealed vascular smooth muscle cell growth. The remodeling data are expressed mathematically in terms of indicial functions, i.e., change of a particular feature of a blood vessel in response to a unit step change of blood flow. The indicial function approach provides a quantitative description of the remodeling process in the blood vessel wall.

Characterization of a Bacteroides mobilizable transposon, NBU2, which carries a functional lincomycin resistance gene

The mobilizable Bacteroides element NBU2 (11 kbp) was found originally in two Bacteroides clinical isolates, Bacteroides fragilis ERL and B. thetaiotaomicron DOT. At first, NBU2 appeared to be very similar to another mobilizable Bacteroides element, NBU1, in a 2.5-kbp internal region, but further examination of the full DNA sequence of NBU2 now reveals that the region of near identity between NBU1 and NBU2 is limited to this small region and that, outside this region, there is little sequence similarity between the two elements. The integrase gene of NBU2, intN2, was located at one end of the element. This gene was necessary and sufficient for the integration of NBU2. The integrase of NBU2 has the conserved amino acids (R-H-R-Y) in the C-terminal end that are found in members of the lambda family of site-specific integrases. This was also the only region in which the NBU1 and NBU2 integrases shared any similarity (28% amino acid sequence identity and 49% sequence similarity). Integration of NBU2 was site specific in Bacteroides species. Integration occurred in two primary sites in B. thetaiotaomicron. Both of these sites were located in the 3' end of a serine-tRNA gene NBU2 also integrated in Escherichia coli, but integration was much less site specific than in B. thetaiotaomicron. Analysis of the sequence of NBU2 revealed two potential antibiotic resistance genes. The amino acid sequences of the putative proteins encoded by these genes had similarity to resistances found in gram-positive bacteria. Only one of these genes was expressed in B. thetaiotaomicron, the homolog of linA, a lincomycin resistance gene from Staphylococcus aureus. To determine how widespread elements related to NBU1 and NBU2 are in Bacteroides species, we screened 291 Bacteroides strains. Elements with some sequence similarity to NBU2 and NBU1 were widespread in Bacteroides strains, and the presence of linA(N) in Bacteroides strains was highly correlated with the presence of NBU2, suggesting that NBU2 has been responsible for the spread of this gene among Bacteroides strains. Our results suggest that the NBU-related elements form a large and heterogeneous family, whose members have similar integration mechanisms but have different target sites and differ in whether they carry resistance genes.

Genetic variation of Japanese encephalitis virus in Taiwan

A 280-nucleotide sequence from the capsid-premembrane (C/preM) gene region of 44 Japanese encephalitis (JE) virus strains isolated in Taiwan from mosquitoes from 1983 to 1994, and 3 strains, (Ling [1965], Chang [1965], and HV1 [1958]) isolated from human brain were analyzed by direct sequencing of reverse transcription-polymerase chain reaction (RT-PCR) amplified products and compared with the corresponding sequences of reference strains. The overall sequence homology of the 47 isolates was > or = 93.3%. Taking 12% nucleotide divergence as a cut-off value, all isolates fell into genotype 3, which included strains from Japan, China, the Philippines, Sri Lanka, India, and Nepal. High nucleotide homology was observed among isolates from different regions of Taiwan and different time periods; on the other hand, high variation existed among isolates from the same region and time period. Phylogenetic analysis showed that the 47 Taiwan isolates fell into three clusters. Twenty-five isolates formed cluster 1, 18 isolates cluster 2, and four isolates cluster 3. Isolates in cluster 1 showed greater (< or = 2.9%) intragroup divergence compared to those in cluster 2 (< or = 1.1%) or cluster 3 (< or = 0.7%). The majority of isolates from northern (73.3%) and central (60%) Taiwan belonged to cluster 1, whereas most isolates (66.7%) from southern Taiwan belonged to cluster 2. Comparison with other Asian JE virus strains showed that isolates of cluster 1 were more specific to Taiwan than isolates of cluster 2 and cluster 3.

Multiple gene products and sequences required for excision of the mobilizable integrated Bacteroides element NBU1

NBU1 is an integrated 10.3-kbp Bacteroides element, which can excise and transfer to Bacteroides or Escherichia coli recipients, where it integrates into the recipient genome. NBU1 relies on large, >60-kbp, conjugative transposons for factors that trigger excision and for mobilization of the circular form to recipients. Previously, we showed that a single integrase gene, intN1, was necessary and sufficient for integration of NBU1 into its target site on the Bacteroides or E. coli genome. We now show that an unexpectedly large region of NBU1 is required for excision. This region includes, in addition to intN1, four open reading frames plus a large region downstream of the fourth gene, prmN1. This downstream sequence was designated XRS, for "excision-required sequence." XRS contains the oriT of the circular form of NBU1 and about two-thirds of the adjacent mobilization gene, mobN1. This is the first time an oriT, which is involved in conjugal transfer of the circular form, has been implicated in excision. Disruption of the gene immediately downstream of intN1, orf2, completely abolished excision. The next open reading frame, orf2x, was too small to be disrupted, so we still do not know whether it plays a role in the excision reaction. Deletions were made in each of two open reading frames downstream of orf2x, orf3 and prmN1. Both of these deletions abolished excision, indicating that these genes are also essential for excision. Attempts to complement various mutations in the excision region led us to realize that a portion of the excision region carrying prmN1 and part of the XRS (XRS(HIII)) inhibited excision when provided in trans on a multicopy plasmid (8 to 10 copies per cell). However, a fragment carrying prmN1, XRS, and the entire mobilization gene, mobN1, did not have this effect. The smaller fragment may be interfering with excision by attracting proteins made by the intact NBU1 and thus removing them from the excision complex. Our results show clearly that excision is a complex process that involves several proteins and a cis-acting region (XRS) which includes the oriT. We suggest that this complex excision machinery may be necessary to allow NBU1 to coordinate nicking at the ends during excision and nicking at the oriT during conjugal transfer, to prevent premature nicking at the oriT before NBU1 has excised and circularized.

Bacteriophage T4 self-assembly: localization of gp3 and its role in determining tail length

Gene 3 of bacteriophage T4 participates at a late stage in the T4 tail assembly pathway, but the hypothetical protein product, gp3, has never been identified in extracts of infected cells or in any tail assembly intermediate. In order to overcome this difficulty, we expressed gp3 in a high-efficiency plasmid expression vector and subsequently purified it for further analysis. The N-terminal sequence of the purified protein showed that the initial methionine had been removed. Variant C-terminal amino acid sequences were resolved by determining the cysteine content of the protein. The molecular mass of 20.6 kDa for the pure protein was confirmed by Western blotting, using a specific anti-gp3 serum for which the purified protein was the immunogen. We also demonstrated, for the first time, the physical presence of gp3 in the mature T4 phage particle and localized it to the tail tube. By finding a nonleaky, nonpermissive host for a gene 3 mutant, we could clearly demonstrate a new phenotype: the slow, aberrant elongation of the tail tube in the absence of gp3.

Bacteriophage T4 self-assembly: in vitro reconstitution of recombinant gp2 into infectious phage

T4 gene 2 mutants have a pleiotropic phenotype: degradation of injected phage DNA by exonuclease V (ExoV) in the recBCD(+) host cell cytoplasm and a low burst size due, at least in part, to a decreased ability for head-to-tail (H-T) joining. The more N terminal the mutation, the more pronounced is the H-T joining defect. We have overexpressed and purified the recombinant gene 2 product (rgp2) to homogeneity in order to test its role in H-T joining, during in vitro reconstitution. When we mix extracts of heads from a gp2(+) phage infection (H(+)) with tails from a gp2(+) or gp2(-) phage infection (T(+) or T(-)), the H-T joining is fast and all of the reconstituted phage grow equally well on cells with or without ExoV activity. When heads from gene 2 amber mutants (H(-)) are used, addition of rgp2 is required for H-T joining. In this case, H-T joining is slow and only about 10% of the reconstituted phage can form plaques on ExoV(+) cells. When extracts of heads with different gene 2 amber mutations are mixed with extracts of tails (with a gene 2 amber mutation) in the presence of rgp2, we find that the size of the gp2 amber peptide of the head extract is inversely related to the fraction of reconstituted phage with a 2(+) phenotype. We conclude that free rgp2 is biologically active and has a direct role in H-T joining but that the process is different from H-T joining promoted by natural gp2 that is incorporated into the head in vivo. Furthermore, it seems that gp2 has a domain which binds it to the head. Thus, the presence of the longer gp2am mutants (with this domain) inhibits their replacement by full-length rgp2.

The effect of allergen immunotherapy on in vitro IL-4 and IFN-gamma production by peripheral mononuclear cells in house dust-sensitive Chinese patients with bronchial asthma

The IFN-gamma produced by Th1 cells and IL-4 produced by Th2 cells are two most important cytokines in the regulation of IgE production. House dust immunotherapy has been tried in the treatment of house dust-sensitive Chinese asthmatic patients with good results. We examined the influence of such treatment on in vitro IL-4 and IFN-gamma production by peripheral blood mononuclear cells in house dust-sensitive asthmatic patients. Allergen immunotherapy in house-dust sensitive asthmatic patients can significantly decrease IL-4 production from peripheral mononuclear cells (p<0.05). The production levels of IL-4 in patients without treatment had higher levels than those in patients with hyposensitization (p<0.01). Such therapy also have some effect on promotion of IFN-gamma production in asthmatic patients. In conclusion, immunotherapy with house dust may have the potential ability to shift the Th1/Th2 balance of immune response to allergens and to create a favorable cytokine microenvironment to suppress the allergic reaction in the asthmatic airway.

The epidemiology of Japanese encephalitis on Taiwan during 1966-1997

Japanese encephalitis (JE) is an endemic disease in Taiwan. A mass vaccination program of children against JE was first implemented in 1968. Along with general improvements in various aspects of living conditions over the years, the program has brought JE well under control. The main characteristics of JE epidemiology in Taiwan in the past 3 decades are as follows. The transmission mode remains unchanged-that is, the amplification stage of the virus in pigs is followed by a human epidemic each year. The frequency of JE incidence has dropped significantly. The incidence rate of confirmed cases was 2.05 per 100,000 in 1967, the highest in record, and merely 0.03 per 100,000 in 1997. Confirmed cases occur sporadically all over the island. The peak of the epidemic season has shifted from August in the 1960s to June since the 1980s. The age distribution of confirmed cases has shifted gradually from mainly children to adults. Vaccine efficacy for those having received more than 2 doses of the vaccine is estimated to be about 85%.

Preliminary studies on target antigens for the diagnosis of Trichomonas vaginalis infection

Trichomonas vaginalis, a parasitic protozoa residing in the human urogenital tract, causes one of the most common sexually transmitted diseases, trichomoniasis. Clinical diagnosis of T. vaginalis infection mainly involves a wet-mount microscopic examination, and a culture method, and both of which are either laborious or time-consuming. An immunodiagnostic strategy is under development, which is based on the fact that T. vaginalis releases various protein factors, notably proteinases, into the culture medium, some of which can also be detected in vaginal washes. These factors are closely related to the clinical presentation of trichomonad vaginitis, and thusly may serve as potential earmarks for diagnosis. We have attempted to identify the most appropriate target antigen(s) by screening and analyzing the profile of T. vaginalis antigens existing in patient's vaginal secretion, using the antiserum raised against the total secretory antigens from T. vaginalis cultures. Two T. vaginalis antigens with molecular weights near 110 KDa have been demonstrated to be useful antigens as the diagnostic markers.

[Molecular typing of Taiwanese Orientia tsutsugamushi isolates by restriction fragment profile]

Scrub typhus, which is caused by Orientia tsutsugamushi, is one of the reportable diseases in Taiwan, ROC. Positive cases seemed to be increasing in recent years and our laboratory had confirmed a total of 247 cases in 1997. In this study, 71 strains of O. tsutsugamushi were isolated from heparinized blood of the patients by cell culture, and their DNA was isolated. Two-step polymerase chain reaction was then used to amplify a specific sequence from the DNA, which was digested with restriction enzymes, Hha I and Sfa NI, for typing. With this technique, 34 strains gave rise to the same profile as that of the Kuroki type, 6 as the Karp type and 2 as the Gilliam type. The remaining 28 strains produced fragment profiles different from those of types Karp, Kato, Kawasaki, Kuroki, Gilliam and Shimokoshi and, therefore, were classified as 6 new types designated Taiwan A to Taiwan F, respectively. These strains with profiles different from those of the standard Japanese strains may represent the local mutant strains.

Anti-GD1a antibody is associated with axonal but not demyelinating forms of Guillain-Barré syndrome

Immunopathological studies suggest that the target of immune attack is different in the subtypes of Guillain-Barré syndrome (GBS). In acute motor axonal neuropathy (AMAN), the attack appears directed against the axolemma and nodes of Ranvier. In acute inflammatory demyelinating polyneuropathy (AIDP), the attack appears directed against a component of the Schwann cell. However, the nature of the antigenic targets is still not clear. We prospectively studied 138 Chinese GBS patients and found that IgG anti-GD1a antibodies were closely associated with AMAN but not AIDP. With a cutoff titer of greater than 1:100, 60% of AMAN versus 4% of AIDP patients had IgG anti-GD1a antibodies; with a cutoff titer of greater than 1:1,000, 24% of AMAN patients and none of the AIDP patients had IgG anti-GD1a antibodies. In contrast, low levels of IgG anti-GM1 antibodies (> 1:100) were detected in both the AMAN and the AIDP forms (57% vs 35%, NS). High titers of IgG anti-GM1 (>1:1,000) were more common in the AMAN form (24% vs 8%, NS). Serological evidence of recent Campylobacter infection was detected in 81% of AMAN and 50% of AIDP patients, and anti-ganglioside antibodies were common in both Campylobacter-infected and noninfected patients. Our results suggest that IgG anti-GD1a antibodies may be involved in the pathogenesis of AMAN.

Enterovirus 71 from fatal and nonfatal cases of hand, foot and mouth disease epidemics in Malaysia, Japan and Taiwan in 1997-1998

Enterovirus 71 (EV71), one of the major causative agents for hand, foot and mouth disease (HFMD), is sometimes associated with severe central nervous system diseases. In 1997, in Malaysia and Japan, and in 1998 in Taiwan, there were HFMD epidemics involving sudden deaths among young children, and EV71 was isolated from the HFMD patients, including the fatal cases. The nucleotide sequences of each EV71 isolate were determined and compared by phylogenetical analysis. EV71 strains from previously reported epidemics belonged to genotype A-1, while those from recent epidemics could be divided into two genotypes, A-2 and B. In Malaysia, genotype A-2 was more prevalent, while in Japan and Taiwan, B genotype was more prevalent. Two isolates from fatal cases in Malaysia and one isolate from a fatal case in Japan were genotype A-2. However, all isolates from three fatal cases in Taiwan belonged to genotype B. The severity of the HFMD did not link directly to certain genotypes of EV71.

Mechanism of platelet inhibition by nitric oxide: in vivo phosphorylation of thromboxane receptor by cyclic GMP-dependent protein kinase

Nitric oxide (NO) is a potent vasodilator and inhibitor of platelet activation. NO stimulates production of cGMP and activates cGMP-dependent protein kinase (G kinase), which by an unknown mechanism leads to inhibition of Galphaq-phospholipase C-inositol 1, 4,5-triphosphate signaling and intracellular calcium mobilization for several important agonists, including thromboxane A2 (TXA2). To explore the mechanism of platelet inhibition by NO, activation of platelet TXA2 receptors in the presence of cGMP was studied. The nonhydrolyzable analog 8-bromo-cyclic GMP (8-Br-cGMP) potently inhibited activation of the TXA2-specific GTPase in platelet membranes in a concentration-dependent fashion, suggesting that G kinase catalyzes the phosphorylation of some proximal component of the receptor-G protein signaling pathway. Nanomolar concentrations of G kinase were found to catalyze the phosphorylation of platelet TXA2 receptors in vitro, but not Galphaq copurifying with the TXA2 receptors in these experiments. Using immunoaffinity methods, in vivo phosphorylation of TXA2 receptors by cyclic GMP was demonstrated from 32P-labeled cells treated with 8-Br-cGMP. Peptide mapping studies of in vivo phosphorylated TXA2 receptors demonstrated cGMP mediates phosphorylation of the carboxyl terminus of the TXA2 receptor. G kinase also catalyzed the phosphorylation of peptides corresponding to the cytoplasmic tails of both alpha and beta forms of the receptor but not control peptide or a peptide corresponding to the third intracytoplasmic loop of the TXA2 receptor. These data identify TXA2 receptors as cGMP-dependent protein kinase substrates and support a novel mechanism for the inhibition of cell function by NO in which activation of G kinase inhibits signaling by G protein-coupled receptors by catalyzing their phosphorylation.

Surveillance of anti-hantavirus antibodies among certain high-risk groups in Taiwan

Hemorrhagic fever with renal syndrome is a serious health concern in neighboring countries of Taiwan, such as mainland China and Korea. In Taiwan, only two suspected cases were recorded before 1994. The first confirmed case was reported in 1995, but this proved to be imported. To study hantavirus infection in Taiwan, we tested blood collected from garbage collectors, animal handlers, patients with febrile illness of unknown origin, and field rats, the host of hantavirus, for the presence of antibody against hantavirus using an indirect immunofluorescent antibody technique. The positive rates were 1.55% (3/193), 3.45% (1/29), 1.42% (3/211), and 5.56% (9/162), respectively. The subtypes of hantavirus involved were either Hantaan-like or Seoul-like. These results showed that hantavirus may have already invaded Taiwan without our knowledge and physicians should be aware of this.

Identification of a measles virus isolate from a recent outbreak in northern Taiwan

Specimens were collected during a recent outbreak. Those specimens displaying both CPE positive in B95-8 lymphocyte cell culture and positive by IFA were checked by a RT-PCR with a specific set of measles virus primers derived from the C-terminal of the nucleoprotein. Such RT-PCR method was found ideal for routine diagnostic purposes. Product from this RT-PCR was treated for plasmid construction before transformed into E. coli. One of those transformed clones, i. e. T94, was further studied for its DNA sequence. Since T94 is found to bear several evident different characteristics from those ever published, we conclude that this isolate is neither a vaccine derived strain nor one of those reported previously with specific amino acid residues, but unique in its own right. This isolate can well be a local lineage of wild measles virus in Taiwan.

Temperature effect on the sensitivity of ELISA, PA and WB to detect anti-HIV-1 antibody and infectivity of HIV-1

BACKGROUND

This study is designed to resolve the problem of whether temperature or freeze/thaw cycle will have any impact on the sensitivity for detection of anti-HIV-1 antibody by particle agglutination (PA), enzyme-linked immunosorbent assay (ELISA) and western blotting (WB). To reduce potential risk for laboratory personnel exposed to HIV-infection, it will be useful to determine the temperature effect on HIV infectivity.

METHODS

Testing sera were incubated at different temperatures or treated with several cycles of freeze and thaw. PA, ELISA and WB were used to detect anti-HIV-antibodies, whereas syncytia formation assay and polymerase chain reaction (PCR) were applied to detect HIV-infection.

RESULTS

The data showed that certain temperature points (no treatment, 25 degrees C for 1 hr, 2 hrs and 4 hrs, 37 degrees C for 30 minutes and 60 minutes, 56 degrees C for 30 minutes and 60 minutes, 65 degrees C for 15 minutes and 30 minutes) had no impact on the testing results of ELISA, PA and WB in detection of anti-HIV-1 antibody. In addition, testing results of 50 normal human serum samples which had been heated to 56 degrees C for 30 minutes were still negative by ELISA and PA. Only the samples incubated at 65 degrees C for 60 minutes had slight differences in results. Freeze and thaw treatments of the serum did not alter anti-HIV testing results, either. Treatments of supernatant of HTLV-IIIB culture at 56 degrees C for 30 minutes and 60 minutes, 65 degrees C for 15 minutes and 30 minutes could eliminate the syncytia formation caused by HIV-infection. Further analysis of the samples by PCR was able to detect HIV-specific sequences in all the treatments.

CONCLUSIONS

Anti-HIV antibody is quite stable in serum, even when it is pre-heated to 56 degrees C for 30 minutes. Freeze and thaw treatment of serum samples up to seven cycles did not change the results, either. In addition, to minimize the potential risk of laboratory personnel exposed to HIV infection, pre-treatment of serum samples with heat at 56 degrees C for 30 minutes or 60 minutes can reduce HIV infectivity. However, laboratories still must emphasize the importance of universal precautions rather than heat-inactivation of serum to prevent occupational transmission of HIV.

[Primary surveillance of spotted fever group antibodies on rats in the Kinmen area]

The positive rate of rickettsial antibodies of 107 rats in the Kinmen area by indirect immunofluorescent antibody (IFA) technique was 0% (0/107) in typhus fever, 38.3% (41/107) in scrub typhus and 66.4% (71/107) in spotted fever group; the positive rate (42.9%) of spotted fever group of 21 rats in Taiwan island also higher than scrub typhus (19.0). It suggests that spotted fever group patients may be present in our country but have not been discovered.

Force measurement on fracture site with external fixation

A force measurement device has been designed to monitor the mechanical properties of fracture site with external fixation. Forces are measured through electric resistance strain gauges mounted on fixation framework and the measurement results are displayed on an LCD screen. The device features a force range of 0-10 kg with linearity and repeatability less than 1% and accuracy less than 0.1 kg.

Characterization of four outer membrane proteins that play a role in utilization of starch by Bacteroides thetaiotaomicron

Results of earlier work had suggested that utilization of polysaccharides by Bacteroides spp. did not proceed via breakdown by extracellular polysaccharide-degrading enzymes. Rather, it appeared that the polysaccharide was first bound to a putative outer membrane receptor complex and then translocated into the periplasm, where the degradative enzymes were located. In a recent article, we reported the cloning and sequencing of susC, a gene from Bacteroides thetaiotaomicron that encoded a 115-kDa outer membrane protein. SusC protein proved to be essential for utilization not only of starch but also of intermediate-sized maltooligosaccharides (maltose to maltoheptaose). In this paper, we report the sequencing of a 7-kbp region of the B. thetaiotaomicron chromosome that lies immediately downstream of susC. We found four genes in this region (susD, susE, susF, and susG). Transcription of these genes was maltose inducible, and the genes appeared to be part of the same operon as susC. Western blot (immunoblot) analysis using antisera raised against proteins encoded by each of the four genes showed that all four were outer membrane proteins. Protein database searches revealed that SusE had limited similarity to a glucanohydrolase from Clostridium acetobutylicum and SusG had high similarity to amylases from a variety of sources. SusD and SusF had no significant similarity to any proteins in the databases. Results of 14C-starch binding assays suggested that SusD makes a major contribution to binding. SusE and SusF also appear to contribute to binding but not to the same extent as SusD. SusG is essential for growth on starch but appears to contribute little to starch binding. Our results demonstrate that the binding of starch to the B. thetaiotaomicron surface involves at least four outer membrane proteins (SusC, SusD, SusE, and SusF), which may form a surface receptor complex. The role of SusG in binding is still unclear.

Immunopotentiating activity of Clostridium butyricum in mice

Bacterial vaccine, as generated by heat-inactivated Clostridium butyricum cells, displayed antitumor activity against sarcoma 180 in DDY mice and antimetastatic activity against B16-F10 melanoma in BDF1 mice. According to our results, the vaccine has no direct growth inhibitory effect toward the tumor cell lines tested in this study. The vaccine increased gamma-interferon production, elicited delayed type hypersensitivity reaction, and enhanced IgM antibody formation and mitogenicity. The phagocytic activity of macrophage and killing activity of NK cells from mice were enhanced in a dose-dependent manner by stimulating with the heat-inactivated vaccine. Among those responses in the mice treated with CB, elevated NK cell activity may play a prominent role in manifesting antitumor activity in the B16-F10 metastasis experiment.

NBU1, a mobilizable site-specific integrated element from Bacteroides spp., can integrate nonspecifically in Escherichia coli

NBU1 is an integrated Bacteroides element that can he mobilized from Bacteroides donors to Bacteroides recipients. Previous studies have shown that a plasmid carrying the internal mobilization region of NBU1 could be transferred by conjugation from Bacteroides thetaiotaomicron to Escherichia coli. In this report, we show that NBU1 can integrate in E. coli. Whereas integration of NBU1 in B. thetaiotaomicron is site specific, integration of NBU1 in E. coli was relatively random, and the insertion frequency of NBU1 into the E. coli chromosome was 100 to 1,000 times lower than the frequency of integration in B. thetaiotaomicron. The frequency of NBU1 integration in E. coli could be increased about 10- to 70-fold, to a value close to that seen with B. thetaiotaomicron, if the primary integration site from B. thetaiotaomicron, BT1-1, was provided on a plasmid in the E. coli recipient or the NBU1 integrase gene, intN1, was provided on a high-copy-number plasmid to increase the amount of integrase available in the recipient. When the primary integration site was available in the recipient, NBU1 integrated site specifically in E. coli. Our results show that NBUs have a very broad host range and are capable of moving from Bacteroides spp. to distantly related species such as E. coli. Moreover, sequence analysis of NBU1 integration sites provided by integration events in E. coli has helped to identify some regions of the NBU1 attachment site that may play a role in the integration process.

The Bacteroides mobilizable insertion element, NBU1, integrates into the 3' end of a Leu-tRNA gene and has an integrase that is a member of the lambda integrase family

NBU1 is a 10.3-kbp integrated Bacteroides element that can be induced to excise from the chromosome and can be mobilized to a recipient by trans-acting functions provided by certain Bacteroides conjugative transposons. The NBU1 transfer intermediate is a covalently closed circle, which is presumed to be the form that integrates into the recipient genome. We report here that a 2.4-kbp segment of NBU1 was all that was required for site-specific integration into the chromosome of Bacteroides thetaiotaomicron 5482. This 2.4-kbp region included the joined ends of the NBU1 circular form (attN1) and a single open reading frame, intN1, which encoded the integrase. Previously, we had found that NBU1 integrates preferentially into a single site in B. thetaiotaomicron 5482. We have now shown that the NBU1 target site is located at the 3' end of a Leu-tRNA gene. The NBU1 integrase gene, intN1, was sequenced. The predicted protein had little overall amino acid sequence similarity to any proteins in the databases but had limited carboxy-terminal similarity to the integrases of lambdoid phages and to the integrases of the gram-positive conjugative transposons Tn916 and Tn1545. We also report that the intN1 gene is expressed constitutively.

Identification of serotypes of Rickettsia tsutsugamushi by nested polymerase chain reaction

Nested polymerase chain reaction (PCR) was applied to identify the serotypes of Rickettsia tsutsugamushi isolated from patients. The primers used for PCR were based on the nucleotide sequences encoding a 56 kDa antigen of rickettsiae. Comparing to the conventional immunofluorescence assay (IFA), which displays a considerable degree of cross-reactivity among different species, the result obtained suggests that the polymerase chain reaction method is much more reliable than IFA.

Improved fluorometric quantification of urinary xanthurenic acid

Measurement of urinary xanthurenic acid (XA) has been used clinically to study a variety of disorders caused by vitamin B6 deficiency. To obviate some cumbersome steps of current methods for measuring XA in human urine, we have developed a simple fluorometric method. We apply the urine sample to a solid-phase extraction column containing trimethylaminopropyl group bound to silica, which enables us to purify and concentrate the XA from the urine without contamination from various tryptophan metabolites. The XA in the acidic eluate can then be quantified fluorometrically. The linearity of the proposed method extends from 0.2 to 10.0 mg/L. The method is precise, yielding day-to-day CVs for two pooled control specimens (1.08 and 1.90 mg/L) of 1.2% and 2.6%, respectively. Correlation studies with an established HPLC method and with a spectrophotometric procedure showed correlation coefficients of 0.99 and 0.98, respectively. Interference from vitamin C, uric acid, salicylate, acetaminophen, vanillylmandelic acid, and homovanillic acid was insignificant. The proposed method for urinary XA is rapid, simple, and suitable for routine use in the clinical laboratory.

Improved fluorometric quantification of urinary xanthurenic acid

Measurement of urinary xanthurenic acid (XA) has been used clinically to study a variety of disorders caused by vitamin B6 deficiency. To obviate some cumbersome steps of current methods for measuring XA in human urine, we have developed a simple fluorometric method. We apply the urine sample to a solid-phase extraction column containing trimethylaminopropyl group bound to silica, which enables us to purify and concentrate the XA from the urine without contamination from various tryptophan metabolites. The XA in the acidic eluate can then be quantified fluorometrically. The linearity of the proposed method extends from 0.2 to 10.0 mg/L. The method is precise, yielding day-to-day CVs for two pooled control specimens (1.08 and 1.90 mg/L) of 1.2% and 2.6%, respectively. Correlation studies with an established HPLC method and with a spectrophotometric procedure showed correlation coefficients of 0.99 and 0.98, respectively. Interference from vitamin C, uric acid, salicylate, acetaminophen, vanillylmandelic acid, and homovanillic acid was insignificant. The proposed method for urinary XA is rapid, simple, and suitable for routine use in the clinical laboratory.

ELISA-based colorimetric detection of Rickettsia tsutsugamushi DNA from patient sera by nested polymerase chain reaction

A rapid diagnostic system for scrub typhus was established using colorimetric detection of nested polymerase chain reaction (PCR). This system relied on binding the amplified DNA via a sequence in one of oligodeoxyribonucleotide to the DNA-binding protein GCN4 coated on the well of a micotiter dish. The primer pairs used for the nested PCR were designed on the basis of the homologous nucleotide sequence of the gene that encodes the 56 kDa antigen of serovariants. With this colorimetric PCR, diagnosis can be performed easily from serum samples of patients before the antibody titer increases or in the early stage of the disease. Furthermore, these positive results are able to be confirmed by pathogenic isolation.

Use of a modified Bacteroides-Prevotella shuttle vector to transfer a reconstructed beta-1,4-D-endoglucanase gene into Bacteroides uniformis and Prevotella ruminicola B(1)4

A carboxymethyl cellulase (CMCase) gene from Prevotella ruminicola B(1)4 was reconstructed by adding a cellulose binding domain from a Thermomonospora fusca cellulase and was conjugally transferred from Escherichia coli to Bacteroides uniformis 0061 by using a chloramphenicol and tetracycline resistance shuttle vector (pTC-COW). pTC-COW was specifically constructed to facilitate conjugal transfer of vectors from B. uniformis donors to P. ruminicola recipients. B. uniformis transconjugants containing CMCase constructs cloned into pTC-COW expressed Cmr, but they did not produce the reconstructed CMCase until a xylanase promoter from P. ruminicola 23 was added upstream of the CMCase (pTC-XRCMC). The xylanase promoter allowed the B. uniformis transconjugants to produce large amounts of the reconstructed CMCase, which was present on the outside surface of the cells. Although the reconstructed CMCase alone did not allow B. uniformis to grow on acid-swollen cellulose, rapid growth was observed when two exocellulases were added to the culture supernatant. Under these conditions, the reconstructed CMCase permitted faster growth than the wild-type CMCase. The frequency of transfer of pTC-XRCMC from B. uniformis to P. ruminicola B(1)4 was increased 100-fold when strictly anaerobic conditions, nitrocelluose filters (cell immobilization), and more stringent selections were employed. Although the P. ruminicola B(1)4 (pTC-XRCMC) transconjugates expressed Tcr and had DNA that hybridized with a probe to the shuttle vector, these transconjugants did not produce detectable levels of the reconstructed CMCase even when xylan was the carbon source. On the basis of these results, it appears that not all of the promoters recognized by B. uniformis and P. ruminicola 23 are functional in P. ruminicola B(1)4. However, the results with B. uniformis suggest that the introduction of a P. ruminicola B(1)4 promoter should allow expression of the reconstructed CMCase in P. ruminicola B(1)4.