Ceramide modulates electrophysiological characteristics and oxidative stress of pulmonary vein cardiomyocytes

BACKGROUND

Ceramide is involved in regulating metabolism and energy expenditure, and its abnormal myocardial accumulation may contribute to heart injury or lipotoxic cardiomyopathy. Whether ceramide can modulate the electrophysiology of pulmonary veins (PVs) remains unknown.

MATERIALS AND METHODS

We used conventional microelectrodes to measure the electrical activity of isolated rabbit PV tissue preparations before and after treatment with various concentrations of ceramide with or without H₂ O₂ (2 mM), MitoQ, wortmannin or 740 YP. A whole-cell patch clamp and fluorescence imaging were used to record the ionic currents, calcium (Ca²⁺ ) transients, and intracellular reactive oxygen species (ROS) and sodium (Na⁺ ) in isolated single PV cardiomyocytes before and after ceramide (1 μM) treatment.

RESULTS

Ceramide (0.1, 0.3, 1 and 3 μM) reduced the beating rate of PV tissues. Furthermore, ceramide (1 μM) suppressed the 2 mM H₂ O₂ -induced faster PV beating rate, triggered activities and burst firings, which were further reduced by MitoQ. In the presence of wortmannin, ceramide did not change the PV beating rate. The H₂ O₂ -induced faster PV beating rate could be counteracted by MitoQ or wortmannin with no additive effect from the ceramide. Ceramide inhibited pPI3K. Ceramide reduced Ca²⁺ transients, sarcoplasmic reticulum Ca²⁺ contents, L-type Ca²⁺ currents, Na⁺ currents, late Na⁺ currents, Na⁺ -hydrogen exchange currents, and intracellular ROS and Na⁺ in PV cardiomyocytes, but did not change Na⁺ -Ca²⁺ exchange currents.

CONCLUSION

C2 ceramide may exert the distinctive electrophysiological effect of modulating PV activities, which may be affected by PI3K pathway-mediated oxidative stress, and might play a role in the pathogenesis of PV arrhythmogenesis.

Epicardial adipose tissue modulates arrhythmogenesis in right ventricle outflow tract cardiomyocytes

AIMS

Ventricular arrhythmia (VA) frequently occurs in fatty infiltrative cardiomyopathy or epicardial adipose tissue (EAT) abundant hearts. Right ventricular outflow tract (RVOT), commonly covered with EAT, is vital for VA genesis. This study explored whether EAT contributes to RVOT arrhythmogenesis.

METHODS AND RESULTS

Conventional microelectrodes and whole-cell patch clamp were used to record electrical activity and ionic currents in rabbit RVOT tissue preparation or isolated single cardiomyocytes with or without (control) connected EAT. Epicardial adipose tissue-connected (N = 6) RVOT had more portions of fibrosis than did control (N = 5) RVOT (160.3 ± 23.2 vs. 91.9 ± 13.4 μm2/mm2, P < 0.05). Epicardial adipose tissue-connected RVOT cardiomyocytes (n = 18) had lower negative resting membrane potential (-68 ± 1 vs. -73 ± 2 mV, P < 0.05); smaller action potential (AP) amplitude (108 ± 4 vs. 135 ± 6 mV, P < 0.005); and longer 90%, 50%, and 20% of AP duration repolarization (361 ± 18 vs. 309 ± 9 ms, P < 0.05; 310 ± 17 vs. 256 ± 13 ms, P < 0.05; and 182 ± 19 vs. 114 ± 24 ms, P < 0.05, respectively) than did control (n = 13) RVOT cardiomyocytes. Moreover, compared with control RVOT cardiomyocytes, EAT-connected RVOT cardiomyocytes had larger transient outward potassium currents, similar delayed rectifier potassium currents, smaller L-type calcium currents, and inward rectifier potassium currents. After ajmaline (10 μM, a sodium channel blocker) superfusion, high VA inducibility was observed through rapid pacing in EAT-connected RVOT but not in control RVOT.

CONCLUSIONS

Epicardial adipose tissue exerts distinctive electrophysiological effects on RVOT with a propensity towards VA induction, which might play a role in lipotoxicity pathogenesis-related ventricular arrhythmogenesis.

LncRNA RUSC1-AS1 promotes the proliferation of hepatocellular carcinoma cells through modulating NOTCH signaling

The long non-coding RNA (lncRNA) RUSC1-AS1 has been reported to be dysregulated in the progression of many cancers. Also, RUSC1-AS1 had been detected to be highly expressed in laryngeal squamous cell carcinoma and breast cancer cells, suggesting that RUSC1-AS1 may be a biomarker for cancers. However, the biological role and regulatory mechanism of RUSC1-AS1 in hepatocellular carcinoma (HCC) remain unknown. In this study, we found that RUSC1-AS1 was upregulated in HCC tissues and cells, and predicted unfavorable prognosis of HCC patients. The function assays including colony formation, EdU, TUNEL assay revealed that RUSC1-AS1 facilitated HCC cell proliferation and inhibited HCC cell apoptosis. Furthermore, mechanism assays including luciferase reporter assay and RIP assay demonstrated that RUSC1-AS1 could directly bind to hsa-miR-7-5p. Besides, hsa-miR-7-5p targeted and negatively regulated NOTCH3 expression. Moreover, RUSC1-AS1 sponged hsa-miR-7-5p to upregulate NOTCH3 and to trigger the NOTCH signaling pathway. The rescue assays depicted that RUSC1-AS1 regulated HCC cell proliferation and apoptosis through modulating NOTCH signaling. In conclusion, lncRNA RUSC1-AS1 promoted the proliferation and reduced the apoptosis of HCC cells through activation of NOTCH signaling via hsa-miR-7-5p/NOTCH3 axis.

Various subtypes of phosphodiesterase inhibitors differentially regulate pulmonary vein and sinoatrial node electrical activities

Phosphodiesterase (PDE)3-5 are expressed in cardiac tissue and play critical roles in the pathogenesis of heart failure and atrial fibrillation. PDE inhibitors are widely used in the clinic, but their effects on the electrical activity of the heart are not well understood. The aim of the present study was to examine the effects of various PDE inhibitors on spontaneous cardiac activity and compare those effects between sinoatrial nodes (SANs) and pulmonary veins (PVs). Conventional microelectrodes were used to record action potentials in isolated rabbit SAN and PV tissue preparations, before and after administration of different concentrations (0.1, 1 and 10 µM) of milrinone (PDE3 inhibitor), rolipram (PDE4 inhibitor) and sildenafil (PDE5 inhibitor), with or without the application of isoproterenol (cAMP and PKA activator), KT5823 (PKG inhibitor) or H89 (PKA inhibitor). Milrinone (1 and 10 µM) increased the spontaneous activity in PVs by 10.6±4.9 and 16.7±5.3% and in SANs by 9.3±4.3 and 20.7±4.6%, respectively. In addition, milrinone (1 and 10 µM) induced the occurrence of triggered activity (0/8 vs. 5/8; P<0.005) in PVs. Rolipram increased PV spontaneous activity by 7.5±1.3-9.5±4.0%, although this was not significant, and did not alter SAN spontaneous activity. Sildenafil reduced spontaneous activity in PVs to a greater extent than that seen in SANs. Both KT5823 and H89 suppressed milrinone-increased PV spontaneous activity. In the presence of isoproterenol, milrinone did not alter isoproterenol-induced PV arrhythmogenesis, suggesting that the effects of PDE3 are mediated by the protein kinase G and protein kinase A signaling pathways. In conclusion, inhibitors of different PDE subtypes exert diverse electrophysiological effects on PV and SAN activities.

Predictive Value of Noncontrast Head CT with Negative Findings in the Emergency Department Setting

BACKGROUND AND PURPOSE

Noncontrast head CTs are routinely acquired for patients with neurologic symptoms in the emergency department setting. Anecdotally, noncontrast head CTs performed in patients with prior negative findings with the same clinical indication are of low diagnostic yield. We hypothesized that the rate of acute findings in noncontrast head CTs performed in patients with a preceding study with negative findings would be lower compared with patients being imaged for the first time.

MATERIALS AND METHODS

We retrospectively evaluated patients in the emergency department setting who underwent noncontrast head CTs at our institution during a 4-year period, recording whether the patient had undergone a prior noncontrast head CT, the clinical indication for the examination, and the examination outcome. Positive findings on examinations were defined as those that showed any intracranial abnormality that would necessitate a change in acute management, such as acute hemorrhage, hydrocephalus, herniation, or interval worsening of a prior finding.

RESULTS

During the study period, 8160 patients in the emergency department setting underwent a total of 9593 noncontrast head CTs; 88.2% (7198/8160) had a single examination, and 11.8% (962/8160) had at least 1 repeat examination. The baseline positive rate of the "nonrepeat" group was 4.3% (308/7198). The 911 patients in the "repeat" group with negative findings on a baseline/first CT had a total of 1359 repeat noncontrast head CTs during the study period. The rate of positive findings for these repeat examinations was 1.8% (25/1359), significantly lower than the 4.3% baseline rate (P < .001). Of the repeat examinations that had positive findings, 80% (20/25) had a study indication that was discordant with that of the prior examination, compared with only 44% (593/1334) of the repeat examinations that had negative findings (P < .001).

CONCLUSIONS

In a retrospective observational study based on approximately 10,000 examinations, we found that serial noncontrast head CT examinations in patients with prior negative findings with the same study indication are less likely to have positive findings compared with first-time examinations or examinations with a new indication. This finding suggests a negative predictive value of a prior noncontrast head CT examination with negative findings with the same clinical indication.

Aging Modulates the Substrate and Triggers Remodeling in Atrial Fibrillation

Aging plays a critical role in the genesis of atrial fibrillation (AF) and also increases the risks of cardiac dysfunction and stroke in AF patients. AF is caused by increased AF triggering from abnormalities of the thoracic vein and/or modulated substrate (atrial) with enhancement of AF maintenance. Clinical and laboratory evidence indicates that aging is significant in the creation of atrial electrical and structural remodeling that leads to increased susceptibility to AF occurrence. Aging is commonly associated with cardiovascular comorbidities, oxidative stress, calcium dysregulation, atrial myopathy with apoptosis, and fibrosis, which all contribute to the genesis of AF. This review updates the current understanding of the effects of aging on the pathophysiology of AF.

Mitochondrial dysfunction on sinoatrial node and pulmonary vein electrophysiological activities

Atrial fibrillation (AF) is associated with mitochondrial dysfunction. Sinoatrial node (SAN) dysfunction increases arrhythmogenesis of pulmonary veins (PVs), which is the most important trigger of AF; however, it is not clear whether mitochondrial dysfunction differentially regulates electrical activity of SANs and PVs. In the present study, conventional microelectrodes were used to record the action potentials (APs) in isolated rabbit PVs, SANs, left atrium (LA) and right atrium (RA) before and after application of trifluorocarbonylcyanide phenylhydrazone (FCCP; a mitochondrial uncoupling agent) at 10, 100 and 300 nM. FCCP application at 100 and 300 nM decreased spontaneous rates in PVs and in SANs at 10, 100 and 300 nM. FCCP shortened the 20, 50 and 90% AP durations in the LA, and shortened only the 20% AP duration in the RA. FCCP caused a greater rate reduction in SANs than in PVs; however, in the presence of coenzyme-Q₁₀ (10 µM), FCCP reduced the beating rate in PVs and SANs to a similar extent. In SAN-PV preparations with intact electrical connections, FCCP (100 nM) application shifted the SAN-PV electrical conduction into PV-SAN conduction in 5 (62.5%) of 8 preparations. In conclusion, mitochondrial dysfunction modulates PV and SAN electrical activities, which may contribute to atrial arrhythmogenesis.

Self-adjustment and disintegration threshold of Langmuir solitons in inhomogeneous plasmas

Dynamics of Langmuir solitons in the presence of a background density gradient is investigated numerically, including cases with steep gradients to the extent the solitons can disintegrate. The disintegration threshold is explained by regarding the electric field part of the soliton as a point mass moving along the self-generated potential well corresponding to the density cavity. On the other hand, it is demonstrated that the Langmuir solitons are robust when the density gradient is below the threshold. During the acceleration phase toward low density regions, Langmuir solitons adjust themselves to balance the electric field pressure and the negative plasma pressure by expelling the imbalanced portion as density cavities at the sound velocity. When the density gradient is below the disintegration threshold, the electric field part of the soliton bounces back and forth within the potential well suggesting the solitons have internal structures.

B-Type Natriuretic Peptide Modulates Pulmonary Vein Arrhythmogenesis: A Novel Potential Contributor to the Genesis of Atrial Tachyarrhythmia in Heart Failure

BACKGROUND

Heart failure (HF) plays a critical role in the genesis of atrial fibrillation (AF). A high B-type natriuretic peptide (BNP) level occurs in patients with HF and in patients with AF. However, the role of BNP in the pathophysiology of AF is not clear. The purposes of this study were to evaluate the effects of BNP on pulmonary vein (PV) arrhythmogenesis.

METHODS AND RESULTS

Whole-cell patch clamp and fluorescence were used to study the action potential, ionic currents, and calcium homeostasis in isolated single rabbit PV cardiomyocytes before and after a BNP infusion, with or without ODQ (10 μM), milrinone (50 μM), or ouabain (1 μM). BNP increased PV spontaneous activity by 28.2 ± 7.5% at 100 nM and by 23.8 ± 9.1% at 300 nM. Similar to those with BNP, milrinone 50 μM increased the PV beating rate from 3.0 ± 0.2 to 3.6 ± 0.3 Hz (P < 0.0005, n = 7). In the presence of ODQ application, BNP didn't change PV spontaneous activity. BNP (100 nM) increased calcium transients (F/F₀ from 1.6 ± 0.1 to 1.9 ± 0.2, n = 20, P < 0.05) and increased the pacemaker current (0.4 ± 0.1 to 1.0 ± 0.2 pA/pF, n = 17, P < 0.0005) in PV cardiomyocytes. Moreover, BNP (100 nM) increased the transient inward current, sodium currents, sodium-calcium exchanger currents, and L-type calcium current; but reduced late sodium currents and the Na-K pump in PV cardiomyocytes.

CONCLUSION

BNP increases PV arrhythmogenesis, which may contribute to the genesis of atrial tachyarrhythmogenesis in HF. Cyclic GMP activation, phosphodiesterase 3 inhibition and Na⁺ /K⁺ -ATPase inhibition might participate in the BNP modulation of PV electrophysiology.

Uremic Toxins - Novel Arrhythmogenic Factor in Chronic Kidney Disease - Related Atrial Fibrillation

Atrial fibrillation (AF) is the most common cardiac arrhythmia. Chronic kidney disease (CKD) is associated with a high prevalence of AF, and uremic toxins are an important risk factor for cardiovascular diseases associated with CKD. Uremic toxins can produce pro-fibrotic, pro-hypertrophic, and pro-inflammatory effects on cardiac tissues and enhance oxidative stress or neurohormonal phenomena of cardiovascular injury, which are recognized as arrhythmogenic factors of AF. This article reviews the clinical, molecular, and electrophysiological data of uremic toxins in CKD considered to induce AF through multiple mechanisms on structural and electrical remodeling of the cardiovascular system.

NSD1 mutations generate a genome-wide DNA methylation signature

Sotos syndrome (SS) represents an important human model system for the study of epigenetic regulation; it is an overgrowth/intellectual disability syndrome caused by mutations in a histone methyltransferase, NSD1. As layered epigenetic modifications are often interdependent, we propose that pathogenic NSD1 mutations have a genome-wide impact on the most stable epigenetic mark, DNA methylation (DNAm). By interrogating DNAm in SS patients, we identify a genome-wide, highly significant NSD1^+/−-specific signature that differentiates pathogenic NSD1 mutations from controls, benign NSD1 variants and the clinically overlapping Weaver syndrome. Validation studies of independent cohorts of SS and controls assigned 100% of these samples correctly. This highly specific and sensitive NSD1^+/− signature encompasses genes that function in cellular morphogenesis and neuronal differentiation, reflecting cardinal features of the SS phenotype. The identification of SS-specific genome-wide DNAm alterations will facilitate both the elucidation of the molecular pathophysiology of SS and the development of improved diagnostic testing.

Sotos syndrome is an growth syndrome characterized by advanced growth in childhood, characteristic facial appearance and intellectual disability. Here the authors identify a genome-wide DNA methylation signature that accurately diagnoses Sotos Syndrome and distinguishes it from similar conditions.

Synthesis and Characterization of 4,11-Diaminoanthra[2,3-b]furan-5,10-diones: Tumor Cell Apoptosis through tNOX-Modulated NAD(+)/NADH Ratio and SIRT1

A series of new 4,11-diaminoanthra[2,3-b]furan-5,10-dione derivatives with different side chains were synthesized. Selected 2-unsubstituted derivatives 11-14 showed high antiproliferative potency on a panel of mammalian tumor cell lines including multidrug resistance variants. Compounds 11-14 utilized multiple mechanisms of cytotoxicity including inhibition of Top1/Top2-mediated DNA relaxation, reduced NAD(+)/NADH ratio through tNOX inhibition, suppression of a NAD(+)-dependent sirtuin 1 (SIRT1) deacetylase activity, and activation of caspase-mediated apoptosis. Here, for the first time, we report that tumor-associated NADH oxidase (tNOX) and SIRT1 are important cellular targets of antitumor anthracene-9,10-diones.

Renal failure induces atrial arrhythmogenesis from discrepant electrophysiological remodeling and calcium regulation in pulmonary veins, sinoatrial node, and atria

BACKGROUND

Renal failure (RF) increases the risk of atrial fibrillation (AF), but arrhythmogenic mechanism is unclear. The present study investigated the electrophysiological effects of RF on AF trigger (pulmonary veins, PVs) and substrate (atria) and evaluated potential underlying mechanisms.

METHODS

Electrocardiographic, echocardiographic, and biochemical studies were conducted in rabbits with and without antibiotic-induced mild (creatinine=1.5-6.0 mg/dl) and advanced (creatinine>6.0 mg/dl) RF. Conventional microelectrode techniques, western blotting, and histological examinations were performed using the isolated rabbit PV, left atrium (LA), right atrium (RA) and sinoatrial node (SAN).

RESULTS

Advanced RF rabbits (n=18) had a higher incidence (33.3% vs. 11.1% and 0%, p<0.05) of atrial arrhythmia than mild RF (n=18) and control (n=18) rabbits. Advanced RF rabbits exhibited faster PV spontaneous activities, longer action potential duration (APD) in the LA, higher fibrosis in the LA, and slower SAN beating rates than control rabbits, but had a similar APD and fibrosis in the RA. Caffeine (1 mM) increased advanced RF PV arrhythmogenesis, which is blocked by flecainide (10 μM), or KB-R7943 (10 μM). Moreover, advanced RF rabbits had a higher expression of the Na+/Ca2+ exchanger, protein kinase A, phosphorylated ryanodine receptor (Serine 2808), and phosphorylated phospholamban (Serine 16) in PVs, and a higher expression of Cav 1.2 in the LA, and a lower expression of hyperpolarization-activated cyclic nucleotide-gated potassium channel 4 in the SAN.

CONCLUSIONS

Advanced RF increases atrial arrhythmia by modulating the distinctive electrophysiological characteristics of the PV, LA, and SAN.

Does ethnic variability exist in the systemic exposures of oatp1a2 substrates–fexofenadine in taiwanese?

The aim of this study was to investigate differences in organic anion transporting polypeptide 1A2 activity among the Taiwanese population via an analysis of 3 pharmacokinetic studies completed in a total of 103 healthy male Taiwanese subjects. The pharmacokinetics of fexofenadine was measured as an indicator of organic anion transporting polypeptide 1A2 activity. Using the Kolmogorov-Smirnov test and quantile plots, the frequency distributions of area under the concentration-time curve and concentration were shown to be tri-modal and to represent 3 pharmacokinetic phenotypes. In a comparison with published data, the mean area under the concentration-time curve of fexofenadine in the Taiwanese subjects was similar to that in American, German, and Indian subjects, but significantly different from that in some Asian populations, including Korean and Japanese ethnic groups. These results suggested that Taiwanese subjects showed genetic variation in fexofenadine pharmacokinetics that was associated with differences in organic anion transporting polypeptide 1A2 activity.

Decoy receptor 3 suppresses B cell functions and has a negative correlation with disease activity in rheumatoid arthritis

OBJECTIVES

The decoy receptor 3 (DcR3) is a member of the tumour necrosis factor (TNF) receptor superfamily and may regulate inflammation. The aim of this study was to investigate the role of DcR3 in B cell functions and its correlation to disease activity in patients with rheumatoid arthritis (RA).

METHODS

The concentrations of DcR3 and TNF-α were measured by ELISA. B cell proliferation was assessed by quantification of 3H-thymidine uptake. Staphylococcus aureus Cowan (SAC) strain were used to stimulate B cell proliferation and TNF-α production.

RESULTS

Compared to the osteoarthritis (OA) patients, the RA group had higher synovial DcR3 levels (3273.6±1623.2 vs. 1594.8±1190.0 pg/ml, p=0.003), which were negatively correlated with the serum erythrocyte sedimentation rate and Disease Activity Score using 28 joint counts (DAS28) scores (r=-0.560, p=0.002; r=-0.579, p<0.001, respectively). Although the RA B cells have more active characteristics, B cell proliferation induced by SAC was successfully suppressed by recombinant DcR3.Fc fusion protein with an average inhibition of 44.8%. Moreover, DcR3.Fc fusion protein was found to suppress SAC-induced TNF-α production by B cells in 8 RA patients (average inhibition 47.0%).

CONCLUSIONS

The results of our study indicated that the inhibition of B cell functions by DcR3 may partially explain the negative correlation between DcR3 level and disease activity in RA patients. Our findings imply that DcR3 may be used as a biomarker for disease activity and a potential therapeutic agent in the treatment of RA.

A TR3/Nur77 Peptide-Based High-Throughput Fluorescence Polarization Screen for Small Molecule Bcl-B Inhibitors

Nuclear receptor TR3/Nur77/NR4A1 binds several antiapoptotic Bcl-2-family proteins (Bcl-B, Bcl-2, Bfl-1) in a non-BH3-dependent manner. A 9-amino-acid peptide derived from full-length TR3 with polyarginine tail (TR3-r8) recapitulates TR3's binding specificity, displaying high affinity for Bcl-B. TR3-r8 peptide was used to screen for small molecule Bcl-B inhibitors. A fluorescence polarization assay (FPA) employing fluorescein isothiocyanate (FITC)-labeled TR3-r8 peptide (FITC-TR3-r8) and Bcl-B protein was optimized, with nonfluorescent TR3-r8 serving to demonstrate reversible, competitive binding. Approximately 50,000 compounds were screened at 3.75 mg/L, yielding 145 reproducible hits with ≥50% FITC-TR3-r8 displacement (a confirmed hit rate of 0.29%). After dose-response analyses and counterscreening with an unrelated FITC-based FPA, 6 candidate compounds remained. Nuclear magnetic resonance (NMR) showed that 2 of these compounds bound Bcl-B, but not glutathione S-transferase (GST) control protein. One Bcl-B-binding compound was unable to displace FITClabeled BH3 peptides from Bcl-B, confirming a unique binding mechanism compared with traditional antagonists of antiapoptotic Bcl-2-family proteins. This compound bound Bcl-B with Kd1.94 ± 0.38 µM, as determined by isothermal titration calorimetry. Experiments using Bcl-B overexpressing HeLa cells demonstrated that this compound induced Bcl-B-dependent cell death. The current FPA represents a screen that can identify noncanonical inhibitors of Bcl-2-family proteins. ( Journal of Biomolecular Screening 2008:665-673)

Serotonin reuptake inhibitors attenuate morphine withdrawal syndrome in neonatal rats passively exposed to morphine

Previous investigations had shown that inhibitor of serotonin reuptake transporter (SERT) could attenuate morphine withdrawal syndrome in adult animals. In the present study, we determined whether postnatal injection of serotonin reuptake inhibitors, fluoxetine, clomipramine, or citalopram, is able to attenuate the expression of the naloxone-precipitated morphine withdrawal syndrome in 5-day-old neonatal Sprauge-Dawley rats born to dams rat that received morphine injection since a week before mating till 5 days after delivery. Withdrawal syndrome of morphine, manifested as frequent abdominal stretching and yawning, was generated by injection of naloxone on postnatal day 5. Pre-injection with fluoxetine, clomipramine, or citalopram, significantly attenuated the naloxone-precipitated syndrome in a dose-dependent manner without apparent side effect. The rank order of inhibitory potency is citalopram=clomipramine>fluoxetine. This result suggests that inhibitor of SERT may be of potential in treating neonatal morphine withdrawal syndrome.

Nutritional and Inflammatory Markers in the Prediction of Mortality in Chinese Hemodialysis Patients

BACKGROUND/AIMS

The prevalence of cardiovascular disease and mortality rate is relatively low in Chinese dialysis patients. This study aimed to evaluate the predictive value of nutritional and inflammatory markers in Chinese hemodialysis patients.

METHODS

A total of 158 patients (70 men and 88 women, age 59.9 +/- 13.2 years) were studied. Nutritional and inflammatory markers, including subjective global assessment (SGA), insulin-like growth factor-1, albumin, tumor necrosis factor-alpha, interleukin (IL)-1beta, IL-6, serum amyloid A (SAA), and C-reactive protein (CRP), were measured. These patients were followed up until April 2004 (36 months) to determine the incidence and causes of death.

RESULTS

SGA (p = 0.001), IL-1beta (p = 0.032), SAA (p = 0.031), IL-6 (p = 0.001) and CRP (p < 0.001) were found to be significant predictors of mortality. After adjusting with age, sex, diabetes, coronary artery disease, Kt/Vurea, and duration on dialysis, CRP (odds ratio = 4.58; p = 0.038) and SGA (odds ratio = 6.57; p = 0.004) remained the independent predictors of mortality. The adjusted mortality rate was highest for patients with a high CRP level and malnutrition (assessed by SGA).

CONCLUSIONS

SGA and CRP levels are the most significant predictors of mortality in Chinese dialysis patients. Chinese dialysis patients with a high CRP level tend to be at higher risk of mortality only if they are malnourished.

High-dose CEB vs BEAM with autologous stem cell transplant in lymphoma

Between January 1996 and July 2002, 72 patients with non-Hodgkin's lymphoma or Hodgkin's disease underwent high-dose chemotherapy with autologous stem cell transplant conditioned with either cyclophosphamide, etoposide, carmustine (CEB) or carmustine, etoposide, cytarabine, melphalan (BEAM) at a single institution. In all, 52 patients received CEB and 20 patients received the BEAM regimen. Patient characteristics that were significantly different between the two groups are tumor grade and extranodal involvement (P = 0.0196, 0.0341, respectively). Regimen-related toxicities examined yielded only diarrhea occurring at a higher rate in the BEAM group (81 vs 51%, P = 0.0026), although cases were milder (92 vs 57%). Patients treated with CEB developed mucositis at a slightly higher rate (79%) than patients treated with BEAM (75%), but this difference did not reach statistical significance. However, the mucositis that occurred within the BEAM group was predominately mild (67%) in contrast to the predominance of moderate to severe cases in the CEB group (74%). In addition, patients treated with CEB required growth factor support for a longer time than patients treated with BEAM (P = 0.0399). Response rates were high in both groups, with trends favoring the BEAM group. Overall survival was higher after treatment with BEAM than with CEB (84 vs 60%).

Calcium Regulation of Exocytosis in PC12 Cells

The calcium (Ca(2+)) regulation of neurotransmitter release is poorly understood. Here we investigated several aspects of this process in PC12 cells. We first showed that osmotic shock by 1 m sucrose stimulated rapid release of neurotransmitters from intact PC12 cells, indicating that most of the vesicles were docked at the plasma membrane. Second, we further investigated the mechanism of rescue of botulinum neurotoxin E inhibition of release by recombinant SNAP-25 COOH-terminal coil, which is known to be required in the triggering stage. We confirmed here that Ca(2+) was required simultaneously with the SNAP-25 peptide, with no significant increase in release if either the peptide or Ca(2+) was present during the priming stage as well as the triggering, suggesting that SNARE (soluble N-ethylmaleimide-sensitive fusion protein attachment protein receptor) complex assembly was involved in the final Ca(2+)-triggered event. Using this rescue system, we also identified a series of acidic surface SNAP-25 residues that rescued better than wild-type when mutated, due to broadened Ca(2+) sensitivity, suggesting that this charged patch may interact electrostatically with a negative regulator of membrane fusion. Finally, we showed that the previously demonstrated stimulation of exocytosis in this system by calmodulin required calcium binding, since calmodulin mutants defective in Ca(2+)-binding were not able to enhance release.

A Discontinuous SNAP-25 C-terminal Coil Supports Exocytosis

Membrane fusion requires the formation of four-helical bundles comprised of the SNARE proteins syntaxin, vesicle-associated membrane protein (VAMP), and the synaptosomal-associated protein of 25 kDa (SNAP-25). Botulinum neurotoxin E cleaves the C-terminal coil of SNAP-25, inhibiting exocytosis of norepinephrine from permeabilized PC12 cells. Addition of a 26-mer peptide comprising the C terminus of SNAP-25 that is cleaved by the toxin restores exocytosis, demonstrating that continuity of the SNAP-25 C-terminal helix is not critical for its function. By contrast, vesicle-associated membrane protein peptides could not rescue botulinum neurotoxin D-treated cells, suggesting that helix continuity is critical for VAMP function. Much higher concentrations of the SNAP-25 C-terminal peptide are required for rescuing exocytosis (K(assembly) = approximately 460 microm) than for binding to other SNAREs in vitro (Kd < 5 microm). Each residue of the peptide was mutated to alanine to assess its functional importance. Whereas most mutants rescue exocytosis with lower efficiency than the wild type peptide, D186A rescues with higher efficiency, and kinetic analysis suggests this is because of higher affinity for the cellular binding site. This is consistent with Asp-186 contributing to negative regulation of the fusion process.

Model systems for investigating mucin gene expression in airway diseases

Overproduction of mucus and of mucin glycoproteins and goblet cell hyperplasia occurs in chronic obstructive airway diseases, including asthma and cystic fibrosis. Mucus overproduction results from alterations in several cellular processes, including altered regulation of airway mucin genes on exposure to environmental and infectious agents and to inflammatory mediators. Seven of the nine identified MUC genes (which encode the protein backbone of mucins) are normally expressed in human respiratory tract tissues. Several inflammatory mediators have now been shown to regulate expression of MUC2, MUC5AC, and MUC5B genes. Importantly, mucin gene expression can be regulated both transcriptionally and posttranscriptionally. Current information on airway mucin gene expression is summarized in this review along with an overview of airway epithelial model systems. In vitro model systems include airway epithelial carcinoma cell lines and primary normal human bronchial epithelial (NHBE) cells. In vivo systems include human respiratory tract tissues and rodent airways. Our laboratory has begun to investigate the role of cytokines on mucin gene expression in vitro and in vivo and on goblet cell metaplasia in vivo. Because cytokines can alter cell proliferation, we characterized the effect of interleukin (IL)-4 and IL-13 on the proliferation of NHBE cells and three human lung carcinoma cell lines--A549, NCI-H292, and Calu-3--that are frequently used for analyses of airway mucin gene expression. Both IL-4 and IL-13 had cell-specific effects. They increased proliferation moderately (1.2-3.0-fold) in NHBE and Calu-3 cells, but markedly inhibited proliferation of A549 cells in a dose-dependent manner. IL-4 increased proliferation of NCI-H292 cells moderately, although IL-13 had no significant effect. We also examined the role of IL-13 and IL-4 on MUC5AC messenger RNA (mRNA) expression in A549, Calu-3, and H292 cell lines and did not observe any significant effect. However, we recently showed an increase in Muc-5ac mRNA and protein expression in a murine model of ovalbumin-induced allergic asthma and in murine airways when IL-13 was delivered intranasally (Alimam, N.Z., et al. Am J. Respir. Cell Mol. Biol. 22:253--260). Thus, we speculate that IL-13 plays a role in the differentiation of murine airway epithelial cells into goblet cells, which then express Muc-5ac mRNA. A detailed analysis of the role of cytokines in airway cell differentiation and mucin gene expression both in vitro and in vivo is required to elucidate the roles of mucins in airway health and diseases. Identification of Muc-5ac as a major gene and gene product in goblet cell metaplasia should facilitate delineation of the molecular mechanisms underlying the induction and reversal of airway goblet cell metaplasia and goblet cell hyperplasia.

Sequential SNARE assembly underlies priming and triggering of exocytosis

Changes in SNARE conformations during MgATP-dependent priming of cracked PC12 cells were probed by their altered accessibility to various inhibitors. Dominant negative soluble syntaxin and, to a much lesser extent, VAMP coil domains inhibited exocytosis more efficiently after priming. Neurotoxins and an anti-SNAP25 antibody inhibited exocytosis less effectively after priming. We propose that SNAREs partially and reversibly assemble during priming, and that the syntaxin H3 domain is prevented from fully joining the complex until the arrival of the Ca2+ trigger. Furthermore, we find that mutation of hydrophobic residues of the SNAP25 C-terminal coil that contribute to SNARE core interactions affects the maximal rate of exocytosis, while mutation of charged residues on the surface of the complex affects the apparent affinity of the coil domain for the partially assembled complex.

SNARE-mediated membrane fusion

SNARE proteins have been proposed to mediate all intracellular membrane fusion events. There are over 30 SNARE family members in mammalian cells and each is found in a distinct subcellular compartment. It is likely that SNAREs encode aspects of membrane transport specificity but the mechanism by which this specificity is achieved remains controversial. Functional studies have provided exciting insights into how SNARE proteins interact with each other to generate the driving force needed to fuse lipid bilayers.

SNAREs contribute to the specificity of membrane fusion

Intracellular membrane fusion is mediated by the formation of a four-helix bundle comprised of SNARE proteins. Every cell expresses a large number of SNARE proteins that are localized to particular membrane compartments, suggesting that the fidelity of vesicle trafficking might in part be determined by specific SNARE pairing. However, the promiscuity of SNARE pairing in vitro suggests that the information for membrane compartment organization is not encoded in the inherent ability of SNAREs to form complexes. Here, we show that exocytosis of norepinephrine from PC12 cells is only inhibited or rescued by specific SNAREs. The data suggest that SNARE pairing does underlie vesicle trafficking fidelity, and that specific SNARE interactions with other proteins may facilitate the correct pairing.

Calmodulin and protein kinase C increase Ca(2+)-stimulated secretion by modulating membrane-attached exocytic machinery

The molecular mechanisms underlying the Ca(2+) regulation of hormone and neurotransmitter release are largely unknown. Using a reconstituted [(3)H]norepinephrine release assay in permeabilized PC12 cells, we found that essential proteins that support the triggering stage of Ca(2+)-stimulated exocytosis are enriched in an EGTA extract of brain membranes. Fractionation of this extract allowed purification of two factors that stimulate secretion in the absence of any other cytosolic proteins. These are calmodulin and protein kinase Calpha (PKCalpha). Their effects on secretion were confirmed using commercial and recombinant proteins. Calmodulin enhances secretion in the absence of ATP, whereas PKC requires ATP to increase secretion, suggesting that phosphorylation is involved in PKC- but not calmodulin-mediated stimulation. Both proteins modulate release events that occur in the triggering stage of exocytosis. The half-maximal increase was elicited by 3 nM PKC and 75 nM calmodulin. These results suggest that calmodulin and PKC increase Ca(2+)-activated exocytosis by directly modulating the membrane- or cytoskeleton-attached exocytic machinery downstream of Ca(2+) elevation.

SNARE complex formation is triggered by Ca2+ and drives membrane fusion

Neurotransmitter exocytosis, a process mediated by a core complex of syntaxin, SNAP-25, and VAMP (SNAREs), is inhibited by SNARE-cleaving neurotoxins. Botulinum neurotoxin E inhibition of norepinephrine release in permeabilized PC12 cells can be rescued by adding a 65 aa C-terminal fragment of SNAP-25 (S25-C). Mutations along the hydrophobic face of the S25-C helix result in SNARE complexes with different thermostabilities, and these mutants rescue exocytosis to different extents. Rescue depends on the continued presence of both S25-C and Ca2+ and correlates with complex formation. The data suggest that Ca2+ triggers S25-C binding to a low-affinity site, initiating trans-complex formation. Pairing of SNARE proteins on apposing membranes leads to bilayer fusion and results in a high-affinity cis-SNARE complex.

Syntaxin 13 mediates cycling of plasma membrane proteins via tubulovesicular recycling endosomes

Endocytosis-mediated recycling of plasma membrane is a critical vesicle trafficking step important in diverse biological processes. The membrane trafficking decisions and sorting events take place in a series of heterogeneous and highly dynamic organelles, the endosomes. Syntaxin 13, a recently discovered member of the syntaxin family, has been suggested to play a role in mediating endosomal trafficking. To better understand the function of syntaxin 13 we examined its intracellular distribution in nonpolarized cells. By confocal immunofluorescence and electron microscopy, syntaxin 13 is primarily found in tubular early and recycling endosomes, where it colocalizes with transferrin receptor. Additional labeling is also present in endosomal vacuoles, where it is often found in clathrin-coated membrane areas. Furthermore, anti-syntaxin 13 antibody inhibits transferrin receptor recycling in permeabilized PC12 cells. Immunoprecipitation of syntaxin 13 revealed that, in Triton X-100 extracts, syntaxin 13 is present in a complex(es) comprised of betaSNAP, VAMP 2/3, and SNAP-25. This complex(es) binds exogenously added alphaSNAP and NSF and dissociates in the presence of ATP, but not ATPgammaS. These results support a role for syntaxin 13 in membrane fusion events during the recycling of plasma membrane proteins.

An alpha-helical minimal binding domain within the H3 domain of syntaxin is required for SNAP-25 binding

The interaction between the proteins syntaxin 1A and SNAP-25 is a key step in synaptic vesicle docking and fusion. To define the SNAP-25 binding domain on syntaxin, we have prepared peptides that span the syntaxin H3 domain (residues 191-266), the region previously shown to be important for binding to SNAP-25, and then determined the affinities of these peptides for binding to SNAP-25. A minimal binding domain was identified within a region of 32 amino acids (residues 189-220). Its affinity for SNAP-25 is substantially enhanced by C-terminal extension (residues 221-266). Circular dichroism revealed the presence of substantial alpha-helicity in the H3 domain and in the 32-mer minimal binding domain, but not in H3 peptides that do not bind to SNAP-25. At temperatures that denature the alpha-helix of the minimal binding domain peptide, SNAP-25 binding is lost. Selected mutations in evolutionarily conserved residues of the amphiphilic alpha-helix within the minimal binding domain (e.g., residues 205 and 209) greatly reduce the affinity for SNAP-25 but have no major effect on secondary structure, suggesting that these residues may interact directly with SNAP-25. The H3 domain peptide and the minimal binding domain peptide inhibit norepinephrine release from PC12 cells. These results suggest that specific amino acid residues in the H3 domain, positioned by the underlying alpha-helical structure, are important for its binding to SNAP-25 and support the notion that this interaction is important for presynaptic vesicular exocytosis.

Hrs-2 is an ATPase implicated in calcium-regulated secretion

Associations between proteins present on neurotransmitter-containing vesicles and on the presynaptic membrane are thought to underlie docking and fusion of synaptic vesicles with the plasma membrane, which are obligate steps in regulated neurotransmission. SNAP-25 resides on the plasma membrane and interacts with syntaxin (a plasma membrane t-SNARE) and VAMP (a vesicle v-SNARE) to form a core protein complex thought to be an intermediate in a biochemical pathway that is essential for vesicular transport. We have now characterized a protein, Hrs-2, that interacts with SNAP-25. The binding of Hrs-2 to SNAP-25 is inhibited by calcium in the physiological concentration range that supports synaptic transmission. Furthermore, Hrs-2 binds and hydrolyses nucleoside triphosphates with kinetics that suggest that ATP is the physiological substrate for this enzyme. Hrs-2 is expressed throughout the brain and is present in nerve terminals. Moreover, recombinant Hrs-2 inhibits calcium-triggered 3H-noradrenaline release from permeabilized PC12 cells. Our results suggest a role for Hrs-2 in regulating secretory processes through calcium- and nucleotide-dependent modulation of vesicle-trafficking protein complexes.

Intrathecal morphine for neuropathic pain in a pregnant cancer patient

Although they have been documented, opioid treatments in obstetrics are mostly limited to methadone maintenance treatment in pregnant addicts or analgesia/anesthesia for labor. A literature search revealed no previous studies describing analgesic techniques for relief of severe cancer pain in pregnant patients. As response to morphine is dose-dependent, its conventional use can be problematic in pregnant women suffering from severe cancer pain because it is important to prevent opioid intoxication of the fetus. Furthermore, long-term exposure to morphine may result in physical dependence on the drug by the fetus, causing acute withdrawal syndrome and growth retardation after delivery. We report our experience in treating a 35-year-old pregnant female, in her 32nd gestational week, suffering from neuropathic pain due to advanced ovarian cancer. Using a microcatheter technique, we administered small doses of morphine intrathecally and successfully controlled the pain before delivery without complications in the mother and fetus. Treatment options of systemic vs spinal and epidural vs intrathecal opioids under such unique circumstances are discussed.

["Pinch-off sign" and spontaneous fracture of an implanted central venous catheter: report of a case]

Percutaneous subclavian implantation of an indwelling central venous catheter is an easy technique and provides convenient venous access for long-term intravenous therapy. Although rarely reported, spontaneous fracture of the catheter is an ominous complication which requires a prompt diagnosis and urgent treatment. We present a case of "pinch-off sign" resulting in a spontaneous fracture of an indwelling central venous catheter. A 49-year-old female breast cancer patient was admitted and Port-A-Cath was implanted for chemotherapy. Immediately after the implantation, fluid infusion and blood withdrawal was smooth until clinical "pinch-off sign" developed 3 weeks later. Chest X ray revealed no abnormal findings. Extravasation of antineoplastic drugs was noted 113 days after operation. Fracture of the indwelling catheter was found at the clavicle-rib junction. The fractured fragment was removed with a transvenous snare under fluoroscope. There was no hemodynamic derangement during the peri-operative period. Microscopy studies suggested that intermittent pressure on the catheter between the clavicle and the first rib may be responsible. The catheter wore on the medial side ue to a tearing and scissoring effect associated with free shoulder joint movement exerted additional forces on this wearing point which led to catheter fracture. The relationship between the spontaneous catheter fracture and "pinch-off sign" is reviewed. Our suggestions are: (1) By avoiding the traditional cannulation of the median subclavian vein, the lateral subclavian vein, infraclavicular axillary vein or internal jugular vein should be better routes for implantation. (2) Chest X ray (anterior-posterior and lateral view) should be examined routinely 3 weeks after the operation.(ABSTRACT TRUNCATED AT 250 WORDS)

Continuous succinylcholine infusion and phase II block in short surgical procedures

The study was designed to observe continuous succinylcholine infusion and phase II block in short surgical procedures (duration < 90 min). The characteristics of neuromuscular blockade produced by continuous succinylcholine infusion were observed in 15 adult patients anesthetized with nitrous-oxide-isoflurane (0.7% end tidal concentration) and fentanyl, and were compared with the single-dose technique (n = 13) in recovery time. Ulnar nerve was stimulated supramaximally with repeated train-of-four (interval = 10 sec, frequency = 2 Hz) via surface electrodes at the wrist using an electromyographic monitor (Datex, Relaxograph, Finland). The infusion rate was adjusted to maintain the height of the first twitch (T1) in each train of four at 5-10% of control twitch height. The mean duration of infusion was 50.74 +/- 18.06 minutes. The steady state infusion rate required to maintain 90% to 95% twitch depression was 83.5 +/- 21.4 micrograms/kg/min. Five patients developed phase II block (T4/T1 < 0.5) designated as IB. The other ten did not develop phase II block as IA. Recovery times (T1 = 10.50%, 10-100%) between IA and IB were not statistically significantly different. The recovery time of train-of-four fade (T1 = 10% to T1 = 100% and train of four > 75%) was 5.73 +/- 0.43 minutes. However, recovery times between continuous infusion group and single dose group were significantly different.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of the combined effects of atropine and neostigmine with atropine and edrophonium on the occurrence of postoperative nausea and vomiting

To investigate the effects of different types of anticholinesterase on the incidence of the postoperative nausea and vomiting, 100 ASA class I-II adult premenopausal female patients undergoing elective lower abdominal surgery were randomized into two groups. In both groups, anesthesia was induced with thiopental and fentanyl and 50% nitrous oxide and 0.5-1.5% of isoflurane were used for anesthetic maintenance with succinylcholine 1 approximately 1.5 mg/kg for intubation and atracurium 0.3 mg/kg/hr for maintenance of muscle relaxation. Patients received reversal agents for neuromuscular blockade after operation when the evoked train-of-four (TOF) count returned to four visual responses. A mixture of atropine 8 micrograms/kg and edrophonium 0.75 mg/kg was given to the first group of patients while atropine 15 micrograms/kg and neostigmine 40 micrograms/kg was given to another group of patients. All the patients were observed for the occurrence of nausea or vomiting for 2 hours after the operation in the recovery room. The incidence of nausea was not statistically significantly different in both groups (20% in neostigmine group and 26% in edrophonium group). The occurrence of vomiting was also similar in both groups (8% in neostigmine group and 6% in edrophonium group). We concluded that there were no difference in the incidence of postoperative nausea or vomiting with the use of either neostigmine or edrophonium with atropine for antagonizing neuromuscular blockade after the lower abdominal surgery.

Analyses of surface membrane carbohydrates in parasitic flagellates of the order kinetoplastida using lectins

Crithidia fasciculata, Leishmania donovani, Leishmania major, Leishmania mexicana amazonensis, Leishmania tropica, Leishmania tarentolae, Trypanosoma sp. from Formosan bats (Tb), Trypanosoma lewisi, Trypanosoma musculi, and different strains of Trypanosoma cruzi (Tc) were cultivated at 27 degrees C in a liquid culture medium. Flagellates harvested from log phase culture were analyzed for their lectin agglutinating characteristics with concanavalin A (Con A), Peanut agglutinin, Ricinus communis agglutinin 120, soybean agglutinin (SBA), Ulex europeus agglutinin (UEA) and wheat germ agglutinin (WGA). Results indicated that all these flagellates might have D-galactose and methyl- alpha-D-manopyranoside on their surface. The presence of L-Fucose, which complexes specifically with UEA, could not be demonstrated on the surface of these flagellates. Results from quantitative comparison of surface molecules of Tb and the Tulahuen strain of Tc suggested that Tb may have more WGA-binding molecules while Tc may have more ConA-binding molecules. Pretreatment of the flagellates with 0.05% trypsin at 37 degrees C for 30 minutes caused some reduction of agglutination titers. Cell agglutination with lectins was completely inhibited or reversed in the presence of the specific lectin-binding monosaccharides.

Evidence of the non-infectivity of herpes simplex viral particles in Trichomonas vaginalis

Fan et al., employing an indirect immunofluorescent antibody (IFA) technique, reported the presence of herpes simplex virus type 2 (HSV-2) in Trichomonas vaginalis. However, using the same method, we found that the protozoa showed autofluorescence immediately after acetone fixation. In order to demonstrate the non-infectivity of HSV-2 in T. vaginalis, several other methods were performed in this study. Trichomonads were experimentally incubated together with HSV-2 and examined after immunofluorescent staining procedures. Organisms without any contact with HSV-2 were used as control. Results obtained from both vital stained and methanol-fixed organisms failed to show any fluorescence. Data from DNA fluorochrome staining, immunoblot, electron microscopy and viral titer assay were in accordance with the results of the IFA method. No obvious difference between the freshly isolated and the long term-cultured organisms could be detected by these methods. All strains of T. vaginalis investigated by this study failed to show the presence of intracellular HSV-2.

Studies on growth and distribution of Angiostrongylus cantonensis larvae in Ampullarium canaliculatus

The intramolluscan development of Angiostrongylus cantonensis larvae in Ampullarium canaliculatus, a fresh-water migrant snail which multiplies in tremendous rate in Taiwan, was followed for 28 consecutive days in this study. The snails were infected with first stage larvae of A. cantonensis and groups of three snails were sacrificed daily to study various larval stages in different organs. A. cantonensis larvae were found in all snails examined. During the first four days, they were obtained only from the digestive tract. Mouth is thus suggested as the primary route of natural infection. The first molt was observed on the fifth day of infection, and the second molt, the 12th day. Molting occurred in almost all kinds of organs examined. Studies on tissue tropism showed that the predilection site of A. cantonensis in this freshwater snail was headfoot region. Relatively few larvae were found in visceral organs including liver, heart, and ovary. Most parasites, 62.1%, recovered on the 28th day of infection were third-stage larvae.

Multiple loop purification method for selective cultivation of Pentatrichomonas hominis

It is always troublesome having protozoan cultures contaminated with other organisms in the laboratory. The method described here produces high efficiencies of purification for fast moving flagellate protozoa. A human strain Pentatrichomonas hominis was employed in the study to examine the effects of multiple loop tubes on the purification of flagellates. Trichomonads were harvested from a trypticase yeast extract iron-serum-33 (TYI-S-33) medium, adjusted to 2 X 10(5) organisms/ml, and mixed with an equal volume of 2 X 10(6) organisms/ml of bacteria. The isolation was performed at 37 degrees C in TYI-S-33 medium containing a suitable amount of antibiotics (1000 U/ml of penicillin, 1000 micrograms/ml of streptomycin, and 4 micrograms/ml of fungizone). Four days later, 10(6) organisms/ml of protozoa, free of bacteria, were observed at the other end of the single loop and the double loop tubes. About the same amount of flagellates could be found at the other end of the triple loop tube six days after incubation. The traditional U-shaped tubes were used as controls and 10(5) cells/ml of flagellates were recovered in the presence of bacteria two days after incubation. An axenic culture of P. hominis was successfully isolated from the feces of a Formosan rock-monkey, Macaca cyclopsis, by this method. Purified trichomonads were recovered from a double loop purification tube five days after incubation.

Studies on taeniasis in Taiwan. V. Field trial on evaluation of therapeutic efficacy of mebendazole and praziquantel against taeniasis

Taeniasis is a major public health problem among the aboriginal populations on Taiwan, and is highly prevalent and wide spread in the mountain areas of 10 Counties. Over 27,000 cases of tapeworm infection are estimated influencing the health and economy in the endemic areas. A treatment of taeniasis with mebendazole and praziquantel followed by a re-treatment with atabrine has been done in the field trial, and confirmed that praziquantel is highly effective agent against tapeworm infection, but mebendazole is not. Based upon experiments reported here praziquantel in a single dose of 150 mg, and 450 mg are highly effective against taeniasis and hymenolepiasis respectively.

Comparative studies on epimastigote and metacyclic stages of Trypanosoma cruzi. II. Selective lysis by rodent sera

In a series of immunological studies on Trypanosoma cruzi, the lytic titers of epimastigotes and metacyclic trypomastigotes by sera obtained from normal and infected rodents were compared. Lysis of culture forms of T. cruzi by normal mouse or rat serum was restricted to the epimastigote form. Freezing reduced the lytic titers of rodent sera. This serum lytic activity was also depressed during the acute infection phase. Metacyclic trypomastigotes were more resistant than epimastigotes to both nonspecific and specific lysis by sera, However, provided with fresh complement, antisera collected from mice or rats lysed 12-26% of metacyclic trypomastigotes.