Patterns of baseline autonomic nerve activity and the development of pacing-induced sustained atrial fibrillation

BACKGROUND

Whether autonomic nerve activity is important in the development of pacing-induced sustained atrial fibrillation (AF) is unclear.

OBJECTIVE

The purpose of this study was to test the hypothesis that patterns of baseline autonomic nerve activity are important in the development of pacing-induced sustained AF.

METHODS

Radiotransmitters were implanted in 12 ambulatory dogs to record left stellate ganglion nerve activity (SGNA) and vagal nerve activity (VNA). Sustained (>48 hours) AF was induced with intermittent rapid atrial pacing.

RESULTS

At baseline (before pacing), 1-minute integrated nerve activity between SGNA and VNA demonstrated either a single linear relationship with excellent correlation (group 1, N = 3, r = 0.816 ± 0.105) or nonlinear relationships with poor correlation (group 2, N = 9, r = 0.316 ± 0.162, P <.05 vs group 1). Group 1 dogs had higher VNA (97.0 ± 11.5 mV-s) compared to group 2 (33.4 ± 21.7 mV-s, P <.001). Group 1 dogs had more frequent sympathovagal co-activation episodes than did group 2 (50 ± 19 per day vs 15 ± 6 per day, P <.05) and more paroxysmal atrial tachycardia (PAT; 5 ± 1 per day vs 2 ± 1 per day, P <.05) at baseline. Sustained AF occurred after 16 ± 4 days (range 13-20 days) of pacing in group 1 and after 46 ± 18 days (range 23-72 days) of pacing in group 2 (P <.05). In the week before development of sustained AF, VNA of group 2 dogs was significantly increased compared to baseline (P <.05).

CONCLUSION

Ambulatory dogs with good linear sympathovagal correlation and higher vagal tone at baseline have more PAT episodes at baseline and faster induction of sustained AF by rapid pacing. Rapid atrial pacing increased the VNA of the remaining dogs before induction of sustained AF.

Delayed afterdepolarization in intact canine sinoatrial node as a novel mechanism for atrial arrhythmia

INTRODUCTION

Recent evidence indicates that spontaneous sarcoplasmic reticulum Ca release and Na-Ca exchanger current activation contribute to the sinoatrial node (SAN) automaticity. These findings suggest that SAN activity may share mechanisms that underlie both automaticity and triggered activity. The aim of this study is to test the hypothesis that spontaneous, nonvoltage gated, intracellular Ca (Ca(i)) elevation may induce delayed afterdepolarization (DAD) in intact SAN during isoproterenol infusion.

METHODS AND RESULTS

We simultaneously mapped Ca(i) and membrane potential in 31 isolated Langendorff-perfused canine right atriums (RA). Isoproterenol increased heart rate and late diastolic Ca(i) elevation (LDCAE) of the superior SAN, leading to consistent SAN automaticity in all 31 RAs. However, DAD-like diastolic depolarizations (DD) were transiently observed in 4 RAs during isoproterenol infusion. These DAD-like DDs were preceded by LDCAE, but did not trigger a full action potential. The LDCAE preceding DAD-like DDs had smaller amplitude (0.41 ± 0.08 AU vs 0.48 ± 0.07 AU, P = 0.001) and less steep slopes (3.7 ± 1.3 AU/s vs 4.8 ± 1.4 AU/s, P = 0.001) than that of sinus beats. The coupling interval of DAD-like DDs was longer than that of the preceding normal beats (407 ± 48 ms vs 371 ± 44 ms, P = 0.002).

CONCLUSION

The isoproterenol-induced LDCAE of superior SAN induced a full action potential in most cases. However, if the LDCAE was too small to trigger an action potential, then it induces only DAD-like DD. The failure of DAD-like DD to consistently trigger a sinus beat is a novel mechanism of atrial arrhythmogenesis.

Long-term prognosis of left ventricular lead

Transvenous left ventricular (LV) lead implantation is on the increase due to cardiac resynchronization therapy (CRT). However, there has been paucity of data on the prognosis of LV lead. Consecutive 32 patients with LV lead for CRT (n=22) or pacemaker (n=10) were subjected. Serial changes in pacing threshold and impedance along with lead-related complications were evaluated. Over 2 yr follow-up, there was no significant change in relative threshold voltage to the initial value (100%, 110%, 89.6%, and 79.6% at baseline, 1, 6, and 24 months respectively, P=0.62) as well as lead impedance (816±272, 650±178, 647±191, and 590±185 ohm at baseline, 1, 6, and 24 months respectively, P=0.80). The threshold change was not affected by lead position, lead polarity, and indication of lead implantation. The cumulative rates of lead revision were 6.3% (n=2) and 9.4% (n=3) in 6 month and 2 yr follow-up, respectively. One case of phrenic nerve capture at left lateral decubitus position was detected 1 month after the implantation. However, there were no serious complications over 2 yr period. In conclusion, transvenous LV lead implantation showed favorable long-term prognosis. Pacing parameters remained stable without significant changes over 2 yr follow-up.

Subclinical coronary artery disease as detected by coronary computed tomography angiography in an asymptomatic population

Background and Objectives

Primary prevention of coronary artery disease (CAD) has become a public health issue, according to increasing awareness of the substantial risks posed by asymptomatic atherosclerosis. The aims of this study were to determine the prevalence and characteristics of subclinical CAD using coronary computed tomography angiography (CCTA), and to evaluate the role of this advanced technology in identifying subclinical CAD in asymptomatic Korean individuals, compared with conventional risk stratification.

Subjects and Methods

We enrolled 4,320 consecutive asymptomatic individuals (61% males, aged 50±9 years), who underwent 64-slice CCTA during a routine health check.

Results

Coronary artery plaques were present in 1,053 (24%) individuals. Significant stenosis (diameter stenosis ≥50%) was identified in 139 (3%) subjects, and most of the significant lesions (87%) were located in the left anterior descending artery. CCTA revealed noncalcified plaques in 5% of subjects with a coronary calcium score of zero (n=801). Although 25% (n=10) of those with noncalcified plaque had significant stenosis, most of them (90%) were classified into low- or moderate-risk groups according to National Cholesterol Education Program risk stratification guidelines. In a young population (age ≤55 years for males, ≤65 years for females), 30% of subjects with significant stenosis were classified into a low-risk group and 60% had low (0 to 100) calcium scores.

Conclusion

Subclinical CAD in asymptomatic individuals cannot be ignored for its considerable prevalence, CCTA may be helpful in identifying at-risk subclinical CAD in a noninvasive manner, especially in the young and traditionally low-risk population.

Calcium dynamics and the mechanisms of atrioventricular junctional rhythm

OBJECTIVES

The purpose of this study was to test the hypothesis that rhythmic spontaneous sarcoplasmic reticulum calcium (Ca) release (the "Ca clock") plays an important role in atrioventricular junction (AVJ) automaticity.

BACKGROUND

The AVJ is a primary backup pacemaker to the sinoatrial node. The mechanisms of acceleration of AVJ intrinsic rate during sympathetic stimulation are unclear.

METHODS

We simultaneously mapped transmembrane potential and intracellular Ca in Langendorff-perfused canine AVJ preparations that did not contain sinoatrial node (n = 10).

RESULTS

Baseline AVJ rate was 37.5 +/- 4.0 beats/min. The wavefront from leading pacemaker site propagated first through the slow pathway, then the fast pathway and atria. There was no late diastolic Ca elevation (LDCAE) at baseline. Isoproterenol up to 3 micromol/l increased heart rate to 100 +/- 6.8 beats/min, concomitant with the appearance of LDCAE that preceded the phase 0 of action potential by 97.3 +/- 35.2 ms and preceded the onset of late diastolic depolarization by 23.5 +/- 3.5 ms. Caffeine also produced LDCAE and AVJ acceleration. The maximal slope of LDCAE and diastolic depolarization always colocalized with the leading pacemaker sites. Ryanodine markedly slowed the rate of spontaneous AVJ rhythm. Isoproterenol did not induce LDCAE in the presence of ryanodine. The I(f) blocker ZD 7288 did not prevent LDCAE or AVJ acceleration induced by isoproterenol (n = 2).

CONCLUSIONS

Isoproterenol and caffeine induced LDCAE and accelerated intrinsic AVJ rhythm. Consistent colocalization of the maximum LDCAE and the leading pacemaker sites indicates that the Ca clock is important to the intrinsic AVJ rate acceleration during sympathetic stimulation.

Short-term autonomic denervation of the atria using botulinum toxin

Background and Objectives

Major epicardial fat pads contain cardiac ganglionated plexi (GP) of the autonomic nervous system. Autonomic denervation may improve the success rate of atrial fibrillation (AF) ablation. This study was designed to elucidate the acute effects of blocking the right atrium-pulmonary vein (RA-PV) and left atrium-inferior vena cava (LA-IVC) fat pads on the electrophysiologic characteristics of the atrium and AF inducibility with a botulinum toxin injection.

Materials and Methods

Eight mongrel dogs were studied. The RA-PV and LA-IVC fat pads were exposed through a median thoracotomy. Botulinum toxin (BT, 50 U to each fat pad, n=6) or normal saline (NS, n=2) was injected in the entire area of two fat pads. The study protocol was applied before injection and repeated at 1, 2, 3, 4, and 5 hours thereafter. The sinus rate, ventricular rate during rapid atrial pacing with a cycle length of 50 ms, and AF inducibility were measured with and without vagal stimulation (VS). Bilateral cervical VS was applied (20 Hz, 0.2 ms, 5.6±2.0 V). AF inducibility was evaluated with burst pacing with 200 impulses at a 50-ms cycle length.

Results

VS effects on the sinus node and AF inducibility were eliminated a few hours after injection of BT; these changes were not observed after injection of NS.

Conclusion

Short-term autonomic denervation of the atria was achieved by blocking the major epicardial GP with BT.

Tachybradycardia in the isolated canine right atrium induced by chronic sympathetic stimulation and pacemaker current inhibition

The mechanisms of sinoatrial node (SAN) dysfunction in patients with chronically elevated sympathetic tone and reduced pacemaker current (I(f); such as heart failure) are poorly understood. We simultaneously mapped membrane potential and intracellular Ca(2+) in the Langendorff-perfused canine right atrium (RA). Blockade of either I(f) (ZD-7288) or sarcoplasmic reticulum Ca(2+) release (ryanodine) alone decreased heart rate by 8% (n = 3) and 16% (n = 3), respectively. Combined treatment of ZD-7288 and ryanodine consistently resulted in prolonged (> or =3 s) sinus pauses (PSPs) (n = 4). However, the middle SAN remained as the leading pacemaking site after these treatments. Prolonged exposure with isoproterenol (0.01 micromol/l) followed by ZD-7288 completely suppressed SAN but triggered recurrent ectopic atrial tachycardia. Cessation of tachycardia was followed by PSPs in five of eight RAs. Isoproterenol initially increased heart rate by 75% from baseline with late diastolic intracellular Ca(2+) elevation (LDCAE) from the superior SAN. However, after a prolonged isoproterenol infusion, LDCAE disappeared in the superior SAN, the leading pacemaker shifted to the inferior SAN, and the rate reduced to 52% above baseline. Caffeine (2 ml, 20 mmol/l) injection after a prolonged isoproterenol infusion produced LDCAE in the SAN and accelerated the SAN rate, ruling out sarcoplasmic reticulum Ca(2+) depletion as a cause of Ca(2+) clock malfunction. We conclude that in an isolated canine RA preparation, chronically elevated sympathetic tone results in abnormal pacemaking hierarchy in the RA, including suppression of the superior SAN and enhanced pacemaking from ectopic sites. Combined malfunction of both membrane and Ca(2+) clocks underlies the mechanisms of PSPs.

Intrinsic cardiac nerve activity and paroxysmal atrial tachyarrhythmia in ambulatory dogs

BACKGROUND

Little is known about the relationship between intrinsic cardiac nerve activity (ICNA) and spontaneous arrhythmias in ambulatory animals.

METHODS AND RESULTS

We implanted radiotransmitters to record extrinsic cardiac nerve activity (ECNA; including stellate ganglion nerve activity and vagal nerve activity) and ICNA (including superior left ganglionated plexi nerve activity and ligament of Marshall nerve activity) in 6 ambulatory dogs. Intermittent rapid left atrial pacing was performed to induce paroxysmal atrial fibrillation or atrial tachycardia. The vast majority (94%) of ligament of Marshall nerve activity were preceded by or coactivated with ECNA (stellate ganglion nerve activity or vagal nerve activity), whereas 6% of episodes were activated alone without concomitant stellate ganglion nerve activity or vagal nerve activity. Paroxysmal atrial fibrillation and atrial tachycardia were invariably (100%) preceded (<5 seconds) by ICNA. Most paroxysmal atrial tachycardia events (89%) were preceded by ICNA and sympathovagal coactivation, whereas 11% were preceded by ICNA and stellate ganglion nerve activity-only activation. Most paroxysmal atrial fibrillation events were preceded only by ICNA (72%); the remaining 28% were preceded by ECNA and ICNA together. Complex fractionated atrial electrograms were observed during ICNA discharges that preceded the onset of paroxysmal atrial tachycardia and atrial fibrillation. Immunostaining confirmed the presence of both adrenergic and cholinergic nerve at ICNA sites.

CONCLUSIONS

There is a significant temporal relationship between ECNA and ICNA. However, ICNA can also activate alone. All paroxysmal atrial tachycardia and atrial fibrillation episodes were invariably preceded by ICNA. These findings suggest that ICNA (either alone or in collaboration with ECNA) is an invariable trigger of paroxysmal atrial tachyarrhythmias. ICNA might contaminate local atrial electrograms, resulting in complex fractionated atrial electrogram-like activity.

Diastolic intracellular calcium-membrane voltage coupling gain and postshock arrhythmias: role of purkinje fibers and triggered activity

RATIONALE

Recurrent ventricular arrhythmias after initial successful defibrillation are associated with poor clinical outcome.

OBJECTIVE

We tested the hypothesis that postshock arrhythmias occur because of spontaneous sarcoplasmic reticulum Ca release, delayed afterdepolarization (DAD), and triggered activity (TA) from tissues with high sensitivity of resting membrane voltage (V(m)) to elevated intracellular calcium (Ca(i)) (high diastolic Ca(i)-voltage coupling gains).

METHODS AND RESULTS

We simultaneously mapped Ca(i) and V(m) on epicardial (n=14) or endocardial (n=14) surfaces of Langendorff-perfused rabbit ventricles. Spontaneous Ca(i) elevation (SCaE) was noted after defibrillation in 32% of ventricular tachycardia/ventricular fibrillation at baseline and in 81% during isoproterenol infusion (0.01 to 1 micromol/L). SCaE was reproducibly induced by rapid ventricular pacing and inhibited by 3 mumol/L of ryanodine. The SCaE amplitude and slope increased with increasing pacing rate, duration, and dose of isoproterenol. We found TAs originating from 6 of 14 endocardial surfaces but none from epicardial surfaces, despite similar amplitudes and slopes of SCaEs between epicardial and endocardial surfaces. This was because DADs were larger on endocardial surfaces as a result of higher diastolic Ca(i)-voltage coupling gain, compared to those of epicardial surfaces. Purkinje-like potentials preceded TAs in all hearts studied (n=7). I(K1) suppression with CsCl (5 mmol/L, n=3), BaCl(2) (3 micromol/L, n=3), and low extracellular potassium (1 mmol/L, n=2) enhanced diastolic Ca(i)-voltage coupling gain and enabled epicardium to also generate TAs.

CONCLUSIONS

Higher diastolic Ca(i)-voltage coupling gain is essential for genesis of TAs and may underlie postshock arrhythmias arising from Purkinje fibers. I(K)(1) is a major factor that determines the diastolic Ca(i)-voltage coupling gain.

Assessment of subclinical coronary atherosclerosis in asymptomatic patients with type 2 diabetes mellitus with single photon emission computed tomography and coronary computed tomography angiography

We evaluated the characteristics of coronary artery disease in asymptomatic patients with type 2 diabetes mellitus (DM) using single photon emission computed tomography (SPECT) and coronary computed tomographic angiography (CCTA). A total of 116 patients with DM without abnormal electrocardiographic findings or evidence of peripheral arterial disease (number of risk factors > or =2; 62 +/- 7 years, 59% men) underwent CCTA and SPECT. Of the 116 patients with DM, 88 (76%) had a normal single photon emission computed tomographic findings, and 28 (24%) had abnormal perfusion defects. Of the 116 patients, 92 (79%) had atherosclerotic plaques (2 +/- 2 segments per subject), and 20 (17%) had significant stenosis seen on CCTA. Patients with DM and normal findings on SPECT had a similar prevalence of atherosclerotic plaque (78% vs 82%), significant stenosis (15% vs 25%), severe stenosis (7% vs 7%), and calcified (40% vs 43%), mixed (49% vs 57%), and noncalcified plaques (26% vs 29%) and a high (>100) coronary artery calcium score (32% vs 29%; all p >0.05) compared to those with abnormal findings on SPECT. During the mid-term follow-up (24 +/- 4 months), 5 cardiac events occurred in patients with DM and normal findings on SPECT, only in those with occult CAD on CCTA: 1 sudden cardiac death and 4 revascularization procedures. In conclusion, a significant percentage of patients with DM and normal eletrocardiographic findings, no peripheral arterial disease, and normal findings on SPECT have evidence of occult CAD on CCTA. Furthermore, a small percentage had had a cardiac event by mid-term follow-up. SPECT showed limited capability to differentiate the coronary risks between patients with DM and no coronary plaque and from those with a certain degree of disease; 2 circumstances that represent different coronary risks.

Association of traditional cardiovascular risk factors with coronary plaque sub-types assessed by 64-slice computed tomography angiography in a large cohort of asymptomatic subjects

OBJECTIVE

Although prior studies have shown that traditional cardiovascular (CV) risk factors are associated with the burden of coronary atherosclerosis, less is known about the relationship of risk factors with coronary plaque sub-types. Coronary computed tomography angiography (CCTA) allows an assessment of both, total disease burden and plaque characteristics. In this study, we investigate the relationship between traditional CV risk factors and the presence and extent of coronary plaque sub-types in a large group of asymptomatic individuals.

METHODS

The study population consisted of 1015 asymptomatic Korean subjects (53+/-10 years; 64% were males) free of known CV disease who underwent 64-slice CCTA as part of a health screening evaluation. We analyzed plaque characteristics on a per-segment basis according to the modified American Heart Association classification. Plaques in which calcified tissue occupied more than 50% of the plaque area were classified as calcified (CAP), <50% calcified area as mixed (MCAP), and plaques without any calcium as non-calcified (NCAP).

RESULTS

A total of 215 (21%) subjects had coronary plaque while 800 (79%) had no identifiable disease. Multivariate regression analysis demonstrated that increased age (per decade) and gender are the strongest predictors for the presence of any coronary plaque or the presence of at least one segment of CAP and MCAP (any plaque-age: OR 2.89; 95% CI 2.34, 3.56; male gender: OR 5.21; 95% CI 3.20, 8.49; CAP-age: OR 2.75; 95% CI 2.12, 3.58; male gender: 4.78; 95% CI 2.48, 9.23; MCAP-age: OR 2.62; 95% CI 2.02, 3.39; male gender: OR 4.15; 95% CI 2.17, 7.94). The strongest predictors for the presence of any NCAP were gender (OR 3.56; 95% CI 1.96-6.55) and diabetes mellitus (OR 2.87; 95% CI 1.63-5.08). When looking at the multivariate association between the presence of >/=2 coronary segments with a plaque sub-type and CV risk factors, male gender was the strongest predictor for CAP (OR 7.31; 95% CI 2.12, 25.20) and MCAP (OR 5.54; 95% CI 1.84, 16.68). Alternatively, smoking was the strongest predictor for the presence of >/=2 coronary segments with NCAP (OR 4.86; 95% CI 1.68, 14.07). Low-density lipoprotein cholesterol (LDL-C) was only a predictor for the presence and extent of mixed coronary plaque.

CONCLUSION

Age and gender are overall the strongest predictors of atherosclerosis as assessed by CCTA in this large asymptomatic Korean population and these two risk factors are not particularly associated with a specific coronary plaque sub-type. Smoking is a strong predictor of NCAP, which has been suggested by previous reports as a more vulnerable lesion. Whether a specific plaque sub-type is associated with a worse prognosis is yet to be determined by future prospective studies.

Recombinant human epidermal growth factor treatment of radiation-induced severe oral mucositis in patients with head and neck malignancies

Mucositis of the oral cavity and pharynx is a major dose-limiting factor in the application of radiotherapy (RT) to patients with head and neck cancer. Therefore, we evaluated the wound healing effect of human recombinant epidermal growth factor (rhEGF) in head and neck cancer and lymphoma patients with irradiation (with or without combined chemotherapy-induced oral mucositis). Patients at Asan Medical Center who had undergone definitive RT of the head and neck region with or without combined chemotherapy and who had developed severe oral mucositis (higher than the Radiation Therapy Oncology Group grade 3) were treated with topical rhEGF twice daily for 7 days. The evaluation of response with regard to oral mucositis was performed 1 week later. Of the 11 treated patients, three had nasopharyngeal carcinoma, three had carcinoma of the oropharynx, two had carcinoma of the oral cavity, one had carcinoma of the hypopharynx and two had lymphoma of the head and neck. Six patients received RT only, and five patients received concurrent chemoradiotherapy. All patients showed improvements in their oral mucositis after topical treatment with rhEGF in that the Radiation Therapy Oncology Group grade was significantly decreased (P = 0.0000). This finding suggests that rhEGF is effective and safe for the treatment of radiation-induced mucositis. Further studies are needed to determine the optimal dosage and fractionation schedule.

Usefulness of 64-slice multidetector computed tomography as an initial diagnostic approach in patients with acute chest pain

BACKGROUND

Recently, multidetector computed tomography (MDCT) has been proposed as an accurate diagnostic tool to evaluate for coronary artery disease. However, the role of MDCT as part of the initial diagnostic for evaluating acute chest pain is less well established.

METHODS

We prospectively enrolled patients presenting with acute chest pain to the emergency department (ED) and risk stratified them based on the pretest probability for an acute coronary syndrome (ACS): (1) very low, (2) low, (3) intermediate, (4) high, and (5) very high or definite. After exclusion of very low and very high risk patients, 268 patients were randomized to either immediate 64-slice cardiac MDCT or a conventional diagnostic strategy. Number of admissions, ED and hospital length of stay (LOS), and major adverse cardiac events over 30 days of follow-up were compared between the strategies based on the pretest probability for ACS.

RESULTS

The number of patients ultimately diagnosed with an ACS did not differ between the 2 strategies. Emergency department LOS and total admissions were not different between strategies. Patients in the MDCT-based strategy had a decreased hospital LOS (P = .049) and fewer admissions deemed unnecessary (P = .007). Reductions in unnecessary admissions were more prominent in intermediate-risk patients (P = .015). None of the patients discharged from the ED in the MDCT-based strategy experienced major adverse cardiac events at follow-up.

CONCLUSION

Use of an MDCT-based strategy in the ED as part of the initial diagnostic approach for patients presenting with acute chest pain is safe and efficiently reduces avoidable admissions in patients with an intermediate pretest probability for ACS.

Typical atrioventricular nodal reentrant tachycardia in a patient with fasciculoventricular pathway

We report a 34-year-old female patient with preexcitation electrocardiogram and recurrent paroxysmal palpitations. Standard 12-lead electrocardiogram showed minimal preexcitation with normal PR interval and normal frontal QRS axis. The electrophysiologic study showed normal AH intervals, short HV intervals, and no change in the degree of preexcitation by rapid atrial pacing. These findings were compatible with the fasciculoventricular pathway. Typical atrioventricular nodal reentrant tachycardia with narrow QRS complex and normal HV interval was induced reproducibly by programmed electrical stimulation. Slow pathway was ablated successfully with radiofrequency catheter ablation, and then the patient remained asymptomatic during a follow-up of 12 months. Although the fasciculoventricular pathway is rare and supraventricular tachycardia in a patient with fasciculoventricular pathway may mimic Wolff-Parkinson-White syndrome, possibility of typical atrioventricular nodal reentrant tachycardia with fasciculoventricular pathway should be considered as a mechanism of supraventricular tachycardia in a patient showing preexcitation electrocardiogram.

Phagocytosis plays an important role in clearing dead cells caused by mono(2-ethylhexyl) phthalate administration

The role of phagocytosis in eliminating apoptotic spermatogenic cells caused by mono(2-ethylhexyl) phthalate (MEHP) was studied. Twenty-one-day-old C57Bl/6N male mice were given a single dose of 800 mg/kg MEHP in corn oil by oral gavage and sacrificed at 1, 3, 5, 7 and 9 days after initial exposure. At the same time, the role of phagocytosis in MEHP related apoptosis was examined using microinjection of annexin V into the seminiferous tubules of living mice. Results showed that mice treated with MEHP had a lower rate of testis weight gain (lower regression line) and a significant TUNEL-positive spermatogenic cell number compared to control. However, this incident was reversible, and the number of TUNEL-positive cells returned to normal after 9 days. Mice microinjected with annexin V and later treated with MEHP showed a large amount of TUNEL-positive cells compared to mice treated with MEHP only. This clearly proves that phagocytosis plays an efficient and highly important role in eliminating dead cells in the injured testis of mice treated with MEHP.

Endoscopic removal of biliary self-expandable metallic stents: a prospective study

BACKGROUND AND STUDY AIMS

The transpapillary endoscopic insertion of self-expandable metallic stents (SEMSs) has been widely used for the palliation of unresectable malignant biliary obstruction. We attempted the endoscopic removal of malfunctioning SEMSs. The aim of this study was to assess the feasibility and safety of the endoscopic removal of SEMSs by comparing the results between removal of covered and uncovered SEMSs.

PATIENTS AND METHODS

30 patients with a malfunctioning biliary SEMS prospectively underwent an attempt at endoscopic removal of the biliary SEMS over a 2-year period. Removal of the malfunctioning SEMS was done with a therapeutic duodenoscope (ED-450XT5 or TJF-240), using a rat-tooth forceps. Of the 30 SEMS used, 22 were silicone-covered Wallstents, while eight were uncovered SEMSs including five uncovered Wallstents and three Zilver stents. The time for an attempt at each endoscopic removal was limited to 15 minutes in a single endoscopic procedure session.

RESULTS

The covered SEMSs were easily removed in 19 out of 22 patients (86.4 %), whereas none of the eight uncovered SEMSs (0 %) could be removed. The only factor predicting successful stent removal was the presence of a stent covering ( P = 0.000). There was no morbidity or mortality related to endoscopic removal of malfunctioning stents.

CONCLUSIONS

In contrast to uncovered biliary SEMSs, in most cases malfunctioning covered biliary SEMSs can be easily and safely removed endoscopically using a rat-tooth forceps.

Endoscopic removal of biliary self-expandable metallic stents: a prospective study

BACKGROUND AND STUDY AIMS

The transpapillary endoscopic insertion of self-expandable metallic stents (SEMSs) has been widely used for the palliation of unresectable malignant biliary obstruction. We attempted the endoscopic removal of malfunctioning SEMSs. The aim of this study was to assess the feasibility and safety of the endoscopic removal of SEMSs by comparing the results between removal of covered and uncovered SEMSs.

PATIENTS AND METHODS

30 patients with a malfunctioning biliary SEMS prospectively underwent an attempt at endoscopic removal of the biliary SEMS over a 2-year period. Removal of the malfunctioning SEMS was done with a therapeutic duodenoscope (ED-450XT5 or TJF-240), using a rat-tooth forceps. Of the 30 SEMS used, 22 were silicone-covered Wallstents, while eight were uncovered SEMSs including five uncovered Wallstents and three Zilver stents. The time for an attempt at each endoscopic removal was limited to 15 minutes in a single endoscopic procedure session.

RESULTS

The covered SEMSs were easily removed in 19 out of 22 patients (86.4 %), whereas none of the eight uncovered SEMSs (0 %) could be removed. The only factor predicting successful stent removal was the presence of a stent covering ( P = 0.000). There was no morbidity or mortality related to endoscopic removal of malfunctioning stents.

CONCLUSIONS

In contrast to uncovered biliary SEMSs, in most cases malfunctioning covered biliary SEMSs can be easily and safely removed endoscopically using a rat-tooth forceps.

Novel index of coronary collateral development as a useful predictor of clinical outcome in type 2 diabetic patients with coronary artery disease

BACKGROUND

There is a paucity of information regarding the impact of the coronary collaterals on prognosis in type 2 diabetic (T2DM) patients. We developed a novel index, which considers not only the degree of collateral circulation but also the stimulus of collateral development, and investigated its prognostic value in T2DM patients with coronary artery disease (CAD).

METHODS AND RESULTS

One hundred and ninety four consecutive T2DM patients were analyzed and followed for an average of 30 months. We measured the diameter stenosis (DS; %), corrected TIMI frame count (CTFC) and Rentrop score at 3 major epicardial coronary arteries. The collateral development (CD) score was calculated by: (Sigma Rentrop score +1)/Sigma [DS (%) x CTFC] x1,000. During the follow-up, acute cardiovascular events occurred in 49 patients. By multivariate analysis, the CD score was an independent predictor of adverse events not only in the total population (p<0.001), but in all 3 subgroups (p=0.020 for coronary artery bypass grafting, p=0.030 for percutaneous transluminal coronary angioplasty (PTCA) and p=0.003 for the medical group). Furthermore, patients in the tertile with the highest CD score showed improved survival by Kaplan-Meier analysis in the total population, the PTCA and the medical group.

CONCLUSIONS

The CD score, a novel index of collateral development, may be a useful predictor of clinical outcome in T2DM patients with CAD.

Association between plasma lipids, and apolipoproteins and coronary artery disease: a cross-sectional study in a low-risk Korean population

BACKGROUND

Due to the lower level of the traditional lipid profiles in Koreans than in the series of patients from the western countries, the need to investigate other lipid parameters to help identify the individuals at high risk of CAD has been emphasized.

AIM AND METHODS

To investigate whether apolipoprotein B (apo B), apolipoprotein A-I (apo A-I) and their ratio give additional information to the traditional lipid risk factors for discriminating the individuals at high-risk for coronary artery disease (CAD), 544 subjects, who met the lipid criteria of total cholesterol (TC) <230 mg/dl, low-density lipoprotein cholesterol (LDL-C) <120 mg/dl and high-density lipoprotein cholesterol (HDL-C) >40 mg/dl were recruited. Patients were considered to be CAD(+) if they had > or =50% stenosis in at least one coronary artery.

RESULTS

In men, TC and apo B/apo A-I ratio were significantly different between groups with and without CAD after adjusting for age and diabetes (P = 0.037 and 0.035), and in women, triglyceride (TG), HDL-C and apo B/apo A-I ratio were significantly different after adjusting for age, diabetes and smoking status (P = 0.006, 0.007 and 0.030, respectively). In the lowest quartile of TC, TG and LDL-C, and the highest quartile of HDL-C, only apo B/apo A-I ratio was associated with CAD in both men and women. The only variable showing a significant difference between patients with and without CAD was apo B/apo A-I ratio. In models assessing whether apolipoproteins give additional information to traditional lipid risk factors, HDL-C, LDL-C, apo B/apo A-I ratio and in women but not in men, TG and apo B were all independent markers for the presence of CAD. Among the nontraditional lipid factors, only apo B/apo A-I ratio showed its additional value for identifying the presence of CAD.

CONCLUSION

Apo B/apo A-I ratio is the only variable that differentiates the patients with CAD from those without and, furthermore, gives additional information to that supplied by traditional lipid risk factors in a low-risk Korean population.

Electrocardiographic Characteristics of Fasciculoventricular Pathways

INTRODUCTION

Fasciculoventricular (FV) pathways are rare variants of preexcitation, and their ECGs may be misinterpreted as Wolff-Parkinson-White syndrome with anteroseptal accessory pathways (WPW-AS). We analyzed the electrocardiographic characteristics of the patients with FV pathways to find out the different findings from WPW-AS.

METHODS AND RESULTS

Five patients with FV pathways and four patients with WPW-AS who underwent electrophysiologic studies were evaluated. Intervals and amplitudes of each wave and QRS morphologies were analyzed in standard 12-lead ECGs of these patients by two independent cardiologists without the information of the electrophysiologic findings. PR intervals were longer in FV pathways (122 +/- 11.0 vs 83 +/- 21 ms, FV pathways vs WPW-AS, P = 0.017). In lead V1, narrower width of R waves (25 +/- 6 vs 45 +/- 13 ms, P = 0.037) and smaller amplitude of S waves (12.8 +/- 8.3 vs 26.6 +/- 7.4 mm, P = 0.037) were observed in FV pathways. The polarity of delta waves in V1 was flat or negative in contrast with the cases of WPW-AS in which the polarity was positive. Three of five patients had notching in the descending limb of S waves in V1, which was not observed in WPW-AS.

CONCLUSION

FV pathways have different ECG characteristics from WPW-AS in PR interval and morphology of QRS complexes in lead V1 of the standard 12-lead ECG.

Relation between deranged antioxidant system and cervical neoplasia

The purpose of this study was to compare the plasma levels of the anti-oxidant system and oxidative stress between a cervical neoplasia group and a normal control group and to investigate the relationship between the levels of micronutrients of antioxidant system and various clinicopathological parameters of cervical carcinoma. A cross-sectional sample of 180 women, including 90 normal controls, was recruited from November 2000 to January 2001. Plasma concentration of malondialdehyde (MDA) was spectrophotometrically measured as the parameter of lipid peroxidation. Plasma levels of antioxidant vitamins were analyzed with the help of reverse-phase, high-pressure liquid chromatography, whereas glutathione peroxidase activity was evaluated by using coupled enzyme procedure. While the activity of glutathione peroxidase and the plasma levels of antioxidant vitamins, such as lutein, beta-carotene, lycopene, and zeaxanthin, were all significantly lower, the concentration of MDA was significantly higher in women with cervical intraepithelial neoplasia (CIN) or invasive cervical cancer, compared to those of the normal control group. The status of the plasma antioxidant system showed no significant correlation with the prognostic factors of cervical cancer. These findings suggest a potential role of oxidative stress-induced lipid peroxidation and the impairment of the anti-oxidant system in the pathogenesis of CIN and carcinoma of the uterine cervix.

Induction of apoptosis by carboplatin and hyperthermia alone or combined in WERI human retinoblastoma cells

This paper investigated the induction of apoptosis and perturbation of cell cycle progression caused by carboplatin (CPt) and hyperthermia alone or combined in WERI human retinoblastoma cells in vitro. An incubation of the cells with 25 or 50 microm of CPt at 37 degrees C caused apoptosis, which progressively increased during the 24-72 h treatment. Hyperthermia at 42.5 degrees C for 1 h induced apoptosis, which became significant from 24 h after the heating. Heating the cells in the presence of CPt and subsequent incubation with CPt was far more effective than treating the cells with hyperthermia or CPt treatment alone in inducing apoptosis in the WERI cells, indicating that the combination of these two modalities is potentially useful for the treatment of retinoblastoma. It appeared that the apoptosis in WERI cells caused by hyperthermia and CPt occurs during G1 phase. An interesting observation was that caspase 9 activation preceded the release of cytochrome C from mitochondria during apoptosis in WERI cells, contrary to the general notion that caspase 9 is activated by cytochrome C.

Phosphorylation of calsenilin at Ser63 regulates its cleavage by caspase-3

Calsenilin is a member of the neuronal calcium sensor (NCS) family of proteins that interacts with the presenilins. Calsenilin has been found to act as a Kv4alpha channel interactor and as a transcriptional repressor. We have recently shown that calsenilin can be cleaved by caspase-3 and that its cleavage separates the conserved calcium-binding domain from the variable N-terminal domain. Here, we demonstrate that calsenilin can be phosphorylated by casein kinase I and that its phosphorylation can be regulated by intracellular calcium. In addition, phosphorylated calsenilin is a substrate for serine/threonine protein phosphatase (PP) 1 and/or 2A. Phosphorylation within the N-terminal domain at Ser63, the major phosphorylation site of calsenilin, inhibits cleavage of the molecule by caspase-3. Given that the N-terminal domain of calsenilin is not conserved in the larger NCS family including other KChIP/CALP proteins, phosphorylation of calsenilin may regulate a functional role that is unique to this member of the superfamily.

Biochemical and immunocytochemical characterization of calsenilin in mouse brain

Mutations in the presenilin 1 and 2 genes cause the majority of early onset familial forms of Alzheimer's disease. Here we describe the biochemical and immunohistochemical characterization of calsenilin, a novel calcium binding protein that we have previously shown to interact with presenilins 1 and 2, in mouse brain. The co-immunoprecipitation of endogenous calsenilin and presenilin 1 demonstrates that these proteins are physiologic binding partners. Although calsenilin has been predicted to be a soluble protein, we have found that the majority of it is tightly associated with the cytoplasmic face of intracellular membranes and that it can only be dissociated using harsh treatments such as urea. In addition, we have demonstrated that calsenilin is a developmentally regulated protein that is mainly present in the brain, where it localizes to both the hippocampus and cerebellum. Calsenilin staining co-localized with the somatodendritic marker microtubule-associated protein-2 primarily in the granular cell layer of the cerebellum, indicating that calsenilin expression is primarily neuronal. In primary cultured neurons, calsenilin immunoreactivity was observed in cell bodies as well as in some neuronal processes. Co-localization experiments using specific axonal and dendritic markers indicate that these processes were mainly axonal in nature, although a smaller subset of dendrites also appears to contain calsenilin. In summary, we have established that calsenilin and presenilin 1 can interact at physiologic levels, and that calsenilin is a developmentally regulated protein that is expressed primarily in the cerebellum and hippocampus. Although calsenilin is a soluble protein, it is tightly associated with the membrane. Finally, the expression pattern of calsenilin, which is similar to that of the presenilin(s), suggests that the common locations of these two proteins provide an opportunity for physical interaction in vivo.

Calsenilin enhances apoptosis by altering endoplasmic reticulum calcium signaling

Calsenilin (also called DREAM and KChIP3), a member of the neuronal calcium sensor family, was isolated in a yeast two-hybrid screen using an apoptotic domain of presenilin 2 as bait. Calsenilin is a cytoplasmic protein, but interacts with the COOH-termini of both presenilin 1 and presenilin 2 at the endoplasmic reticulum and the Golgi apparatus. In this study, we have investigated calsenilin's effect on apoptosis. In stable neuroglioma cell lines, we observed that calsenilin enhances apoptosis in response to serum withdrawal or thapsigargin. Consistent with these observations, caspase and apparently calpain activities were increased during apoptosis in calsenilin-overexpressing cells. Moreover, using calcium imaging we were able to show that cells treated with thapsigargin released more calcium from intracellular stores when calsenilin was overexpressed. Taken together, these data suggest that calsenilin causes cells to be more susceptible to apoptotic triggers, possibly by altering calcium dynamics.

A case of mediastinal angiomyolipoma

Angiomyolipoma is a common tumor of the kidney but has rarely been found in the mediastinum. We report a case of angiomyolipoma of the posterior mediastinum in a 62-year-old woman. She experienced exertional dyspnea and intermittent cough at admission. Computed tomography indicated a tumor located at the left paravertebral and upper posterior mediastinum and MRI imaging demonstrated a mass with low signal intensity in T1-weighted image at T4-5 level. Thoracotomy was done for surgical removal of the tumor and histologic examination revealed a mesenchymal tumor composed of mature fat, capillaries and smooth muscle fibers. The tumor was immunohistochemically positive for CD34 and factor-VIII (for vascular component) smooth muscle actin (for smooth muscle component) and S-100 protein (for fat component). There have been four case reports about mediastinal angiomyolipoma, namely three Japanese cases and one French case. It is suggested that angiomyolipoma could be considered for the differential diagnosis of mediastinal tumors.

Calsenilin is a substrate for caspase-3 that preferentially interacts with the familial Alzheimer's disease-associated C-terminal fragment of presenilin 2

Calsenilin is a member of the recoverin family of neuronal calcium-binding proteins that we have previously shown to interact with presenilin 1 (PS1) and presenilin 2 (PS2) holoproteins. The expression of calsenilin can regulate the levels of a proteolytic product of PS2 (Buxbaum, J. D., Choi, E. K., Luo, Y., Lilliehook, C., Crowley, A. C., Merriam, D. E., and Wasco, W. (1998) Nat. Med. 4, 1177-1181) and reverse the presenilin-mediated enhancement of calcium signaling (Leissring, M. A., Yamasaki, T. R., Wasco, W., Buxbaum, J. D., Parker, I., and LaFerla, F. M. (2000) Proc. Natl. Acad. Sci. U. S. A. 97, 8590-8593). Here, we have used cultured mammalian cells that transiently or stably express calsenilin to extend the characterization of calsenilin and of the calsenilin-PS2 interaction. We have found that calsenilin has the ability to interact with endogenous 25-kDa C-terminal fragment (CTF) that is a product of regulated endoproteolytic cleavage of PS2 and that the presence of the N141I PS2 mutation does not significantly alter the interaction of calsenilin with PS2. Interestingly, when the 25-kDa PS2 CTF and the 20-kDa PS2 CTF are both present, calsenilin preferentially interacts with the 20-kDa CTF. Increases in the 20-kDa fragment are associated with the presence of familial Alzheimer's disease-associated mutations (Kim, T., Pettingell, W. H., Jung, Y., Kovacs, D. M., and Tanzi, R. E. (1997) Science 277, 373-376). However, the finding that the production of the 20-kDa fragment is regulated by the phosphorylation of PS2 (Walter, J., Schindzielorz, A., Grunberg, J., and Haass, C. (1999) Proc. Natl. Acad. Sci. U. S. A. 96, 1391-1396) suggests that it is a regulated physiological event that also occurs in the absence of the familial Alzheimer's disease-associated mutations in PS2. Finally, we have demonstrated that calsenilin is a substrate for caspase-3, and we have used site-directed mutagenesis to map the caspase-3 cleavage site to a region that is proximal to the calcium binding domain of calsenilin.

Preoperative hyperfractionated radiotherapy with concurrent chemotherapy in resectable esophageal cancer

PURPOSE

To evaluate the local control rates, survival rates, and patterns of failure for esophageal cancer patients receiving preoperative concurrent chemotherapy and hyperfractionated radiotherapy followed by esophagectomy.

METHODS AND MATERIALS

From May 1993 through January 1997, 94 patients with resectable esophageal cancers received continuous hyperfractionated radiation (4,800 cGy/40 fx/4 weeks), with concurrent FP chemotherapy (5-FU 1 g/m(2)/day, days 2-6, 30-34, CDDP 60 mg/m(2)/day, days 1, 29) followed by esophagectomy 3-4 weeks later. If there was evidence of disease progression on preoperative re-evaluation work-up, or if the patient refused surgery, definitive chemoradiotherapy was delivered. Minimum follow-up time was 2 years. RESULTS; All patients successfully completed preoperative treatment and were then followed until death. Fifty-three patients received surgical resection, and another 30 were treated with definitive chemoradiotherapy. Eleven patients did not receive further treatment. Among 91 patients who received clinical reevaluation, we observed 35 having clinical complete response (CR) (38.5%). Pathologic CR rate was 49% (26 patients). Overall survival rate was 59.8% at 2 years and 40.3% at 5 years. Median survival time was 32 months. In 83 patients who were treated with surgery or definitive chemoradiotherapy, the esophagectomy group showed significantly higher survival, disease-free survival, and local disease-free survival rates than those in the definitive chemoradiation group.

CONCLUSION

Preoperative chemoradiotherapy in this trial showed improved clinical and pathologic tumor response and survival when compared to historical results. Patients who underwent esophagectomy following chemoradiation showed decreased local recurrence and improved survival and disease-free survival rates compared to the definitive chemoradiation group.

Oxidative stress and neurodegeneration in prion diseases

Transmissible spongiform encephalopathies (TSEs), also termed prion diseases, are a group of fatal neurodegenerative diseases that affect humans and a number of other animal species. The etiology of these diseases is thought to be associated with the conversion of a normal protein, PrPC, into an infectious, pathogenic form, PrPSc. The PrPSc form shows greater protease resistance than PrPC and accumulates in affected individuals, often in the form of extracellular plaques. The pathogenesis and the molecular basis of neuronal cell death in these diseases are not well understood. Oxidative stress has been proposed to play an important role in the pathogenesis of several neurodegenerative disorders. In the present study, evidence of oxidative stress in scrapie, the archetype disease of the TSEs, is discussed. In addition, the mechanisms whereby oxidative stress could lead to neuronal degeneration are described.

Effect of protein kinase C inhibitor (PKCI) on radiation sensitivity and c-fos transcription

PURPOSE

The human genetic disorder ataxia-telangiectasia (AT) is a multisystem disease characterized by extreme radiosensitivity. Although ionizing radiation was known to induce c-fos transcription and cellular protein kinase C (PKC) induces the expression of this immediate response gene, little is known about how mutated AT (ATM) or PKC-mediated signal transduction pathway modulates the c-fos gene transcription and gene expression. Here we have studied the effect of PKC inhibitor (PKCI) on radiation sensitivity and c-fos transcription in normal and AT cells, and also studied whether PKCI effect on c-fos occurs in Ras-dependent pathway.

METHODS AND MATERIALS

Normal (LM217) and AT (AT5BIVA) cells were transfected with PKCI expression plasmid and integration and overexpression of PKCI was evaluated by polymerase chain reaction and northern blotting, respectively. Cells were irradiated at a dose of 5 Gy/min with 137Cs irradiator and harvested 48 h after irradiation and investigated apoptosis with TUNEL method. The c-fos transcription activity was studied by performing compute assisted tomography (CAT) assay of reporter gene after transfection of c-fos CAT plasmid into LM and AT cells. Overexpression of Ras protein in transfected cells was shown by western blotting.

RESULTS

Our results demonstrated for the first time a role of PKCI on the radiation sensitivity and c-fos transcription in LM and AT cells. PKCI increased radiation induced apoptosis in LM cells (5% to 20%) but reduced apoptosis slightly in AT cells. The basal c-fos transcription activity is 70 times lower in AT cells than in LM cells. This c-fos transcription activity was repressed by overexpression of PKCI in LM cells but not in AT cells. After induction of c-fos by Ras protein, overexpression of PKCI repressed c-fos transcription in LM cells but not in AT cells.

CONCLUSIONS

Overexpression of PKCI increased radiation sensitivity and repressed c-fos transcription in LM cells but not in AT cells, and this is related with Ras. These results suggest that the effect of PKCI on c-fos transcription activity is related with Ras dependent signal transduction pathways and these mechanisms are different between normal fibroblasts, LM and ATM mutated, AT cells. The data obtained by this study provided evidence for novel transcriptional difference between LM and AT cells and this may be a reason for increased radiation sensitivity of AT cells.

Increased ferric iron content and iron-induced oxidative stress in the brains of scrapie-infected mice

Scrapie is a transmissible neurodegenerative disease of sheep and goats. The neuropathological changes include vacuolation, astrocytosis, the development of amyloid plaques in some instances, and neuronal loss. The mechanisms involved in neuronal cell death in scrapie are not known. Recently, we reported the presence of oxidative stress in the brains of scrapie-infected animals and suggested that this is the main mechanism that induces neuronal cell loss. It is known that oxidative stress induced by free radicals is associated with iron accumulation; this association led to an examination of the levels of iron (total iron, Fe(2+) and Fe(3+)) in the brains of control and scrapie-infected mice by biochemical methods. In the scrapie-infected group, both the level of total iron and the Fe(3+) level were significantly increased in cerebral cortex, striatum, and brainstem as compared to the values in the control group. A shift in the ratio of Fe(2+)/Fe(3+) was observed in the same regions of infected mice. Additionally, in this scrapie model, we confirmed the presence of oxidative stress, as evidenced by the increase of free malondialdehyde. These results suggest that iron metabolism is changed and that iron-induced oxidative stress partly contributes to neurodegeneration in scrapie infection.

Induction of heme oxygenase-1 in the brains of scrapie-infected mice

Heme oxygenase-1 (HO-1) is an inducible enzyme that catalyzes the rate-limiting step in the degradation of heme to biliverdin, carbon monoxide and iron, and its expression can be used as a marker for oxidative stress. Oxidative stress has been reported to be associated with neurodegenerative diseases including Alzheimer's disease. It is possible that oxidative stress is also involved in the disease process seen in scrapie, the archetype transmissible spongiform encephalopathy. In this study, we report that HO-1 is significantly increased in the scrapie-infected group compared to an age-matched control group. Immunohistochemistry showed a pronounced increase of immunostaining of this protein in the infected group compared to the minimal amount of staining in the control group. These results support that oxidative stress is closely associated with the pathogenesis of scrapie and that it might contribute to neurodegeneration in this disease.

Expression of cyclin E in placentas with hydropic change and gestational trophoblastic diseases: implications for the malignant transformation of trophoblasts

BACKGROUND

Although much is known about the morphologic, cytogenetic, and clinical characters of gestational trophoblastic diseases, little information has appeared concerning the parameters related to their persistence or neoplastic transformation. Cell cycle alterations in tumor tissue were examined in this study in light of obvious changes in the clinical behavior of malignant cells. There is an increasing body of evidence suggesting that the abnormal expression of cyclins is considered one of the most important events in malignant transformation of various human cancers. Among these cell cycle regulators, the role of cyclin E in the neoplastic transformation of trophoblast populations has been poorly defined.

METHODS

Using formalin fixed, paraffin embedded trophoblastic tissues, the authors investigated the expression of cyclin E by immunohistochemistry in placentas with hydropic change and gestational trophoblastic diseases. The specimens examined included tissue from 29 patients with complete hydatidiform mole, 18 patients with partial hydatidiform mole, and 6 patients with choriocarcinoma after term pregnancy or abortion. The authors also studied four cases of hydropic abortion.

RESULTS

The cyclin E indexes (CEI) were as follows: 25.7% +/- 6.2% for hydropic change, 35.3% +/- 12.7% for triploid partial moles, 42.2% +/- 13.1% for diploid/tetraploid complete moles, and 63.6% +/- 9.5% for choriocarcinomas. There was a significant difference in CEI between placentas with hydropic change and partial mole (P = 0.04) and placentas with hydropic change and complete mole (P = 0.003). Choriocarcinomas had significantly higher cyclin E expression compared with placentas, partial moles, and complete moles, respectively. A significant correlation between the expression of cyclin E and S-phase fraction was observed in gestational trophoblastic diseases (rank correlation coefficient = 0.45, P < 0. 05). The relation between cyclin E expression and proliferation was abrogated in placentas with hydropic change, suggesting that cyclin E up-regulation represents a genuine aberration.

CONCLUSIONS

The results of this study were consistent with the concept that cyclin E overaccumulation may play an important role in the uncontrolled proliferation and neoplastic transformation of trophoblasts.

Differential expression of Bax and Bcl-2 in the brains of hamsters infected with 263K scrapie agent

To study the mechanism(s) of neuronal cell death during scrapie infection, we investigated the expression of Bax and Bcl-2 in brains of hamsters infected with 263K scrapie agent. The expression of Bcl-2 mRNA was significantly decreased in the brains of 263K scrapie-infected hamsters compared with controls, whereas the expression levels of Bax mRNA were significantly increased in scrapie-infected brain. The levels of Bax and Bcl-2 proteins in brains of scrapie and control animals reflected the difference in mRNA levels. Immunoreactivity for Bax and Bcl-2 were found predominantly within neurons. In scrapie-infected brains, the number of neuronal cells positive for Bcl-2 was significantly lower in the hippocampal CA3 region and was decreased in the cerebral cortex, whereas the number of neuronal cells positive for Bax was significantly increased in both regions. The possibility that differential regulation of Bax and Bcl-2 expression may play an important role in neuronal cell death induced by scrapie infection is discussed.

Increased expression of CaM kinase II alpha in the brains of scrapie-infected mice

We investigated the distribution of calcium/calmodulin-dependent protein kinase II (CaM kinase II) in the brains of mice infected with ME7 scrapie strain. CaM kinase II is an enzyme that plays a major role in the regulation of long-term potentiation, a form of synaptic plasticity associated with learning and memory. Immunoreactivity of CaM kinase II alpha, measured by Western blot, increased markedly in scrapie-infected brains compared with control brains. Immunohistochemically, CaM kinase II alpha immunoreactivity was upregulated in the cerebral cortex and hippocampal CA1 area of scrapie-positive mice infected with ME7 scrapie strain. This result implies that this enzyme is associated with aberrant function of synaptic transmission and LTP of the pyramidal neurons in the hippocampal CA1 area of mice infected with ME7 scrapie strain.

Increased expression of prion protein is associated with changes in dopamine metabolism and MAO activity in PC12 cells

Prion diseases of humans and animals occur following infection with infectious agents containing PrP(Sc) or in situations in which there is a mutation of the prion protein (PrP) gene. The cellular prion protein (PrP(C)) is a sialoglycoprotein that is expressed predominantly in neurons. PrP(C) is converted into a pathogenic form of PrP (PrP(Sc)), which is distinguishable from PrP(C) by its relative resistance to protease digestion. A number of postulates have been advanced for the function of normal PrP (PrP(C)), but this issue has not been resolved. To investigate the function(s) of PrP(C), we established clonal PC12 cell lines, which have elevated PrP(C) expression. The results show that there were alterations in dopamine metabolism and in monoamine oxidase (MAO) activity in transfected PC12 cells that overexpress PrP(C). There was an increase in concentration of DOPAC, a metabolite of dopamine, and in MAO activity in cells overexpressing PrP(C). MAO is involved in oxidative degradation of dopamine (DA). Our data suggest that PrP(C) plays a role in DA metabolism by regulating MAO activity.

Calsenilin: a calcium-binding protein that interacts with the presenilins and regulates the levels of a presenilin fragment

Most early-onset familial Alzheimer disease (AD) cases are caused by mutations in the highly related genes presenilin 1 (PS1) and presenilin 2 (PS2). Presenilin mutations produce increases in beta-amyloid (Abeta) formation and apoptosis in many experimental systems. A cDNA (ALG-3) encoding the last 103 amino acids of PS2 has been identified as a potent inhibitor of apoptosis. Using this PS2 domain in the yeast two-hybrid system, we have identified a neuronal protein that binds calcium and presenilin, which we call calsenilin. Calsenilin interacts with both PS1 and PS2 in cultured cells, and can regulate the levels of a proteolytic product of PS2. Thus, calsenilin may mediate the effects of wild-type and mutant presenilins on apoptosis and on Abeta formation. Further characterization of calsenilin may lead to an understanding of the normal role of the presenilins and of the role of the presenilins in Alzheimer disease.

Mitochondrial dysfunction induced by oxidative stress in the brains of hamsters infected with the 263 K scrapie agent

Scrapie, one of the prion diseases, is a transmissible neurodegenerative disease of sheep and other animals. Clinical symptoms of prion diseases are characterized by a long latent period, followed by progressive ataxia, tremor, and death. To study the induction of neurodegeneration during scrapie infection, we have analyzed the activities of various antioxidant enzymes and mitochondrial enzymes in cerebral cortex, brain stem, and cerebellum of scrapie-infected hamsters. The activity of mitochondrial Mn-superoxide dismutase (SOD) was decreased, while the activities of cytosolic Cu/Zn-SOD and catalase were not altered in infected brains. The activities of glutathione peroxidase and glutathione reductase were increased in scrapie-infected hamsters. The decreased activity of Mn-SOD might result in increasing oxidative stress in the mitochondria of infected brain; this concept is supported by our findings of a high level of lipid peroxidation, and low levels of ATPase and cytochrome c oxidase activity in the infected cerebral mitochondria. In addition, structural abnormalities of mitochondria have been observed in the neurons of hippocampus and cerebral cortex of infected brain. These results suggest that mitochondrial dysfunction caused by oxidative stress gives rise to neurodegeneration in prion disease.

Expression of inducible nitric oxide synthase in the brains of scrapie-infected mice

The neuronal cell damage caused by inducible nitric oxide synthase (iNOS) in brain has been reported to be associated, at least in part, with many neurodegenerative diseases including Alzheimer's disease. We recently observed vacuolation and astrocytosis in the brains of ME7 scrapie strain-infected C57BL mice. To investigate if these phenomena might have a relationship to iNOS, the level of iNOS expression was measured immunohistochemically and molecular biologically in the brains of scrapie-infected C57BL mice. The number and size of astrocytes were increased and immunoreactivity of glial fibrillary acidic protein (GFAP) was significantly enhanced. iNOS immunoreactivity was observed in the astrocytes of the scrapie-infected group, but not in the control group. iNOS mRNA levels were increased in scrapie-infected mice compared to the levels in non-infected mice of the same age. Our results suggest that iNOS induction in reactive astrocytes is a part of the neurodegenerative mechanisms in scrapie infection.

Molecular analysis of prion protein gene (PRNP) in Korean patients with Creutzfeldt-Jakob disease

Creutzfeldt-Jakob disease (CJD), a relatively uncommon human dementia, is caused by an unconventional slow infectious agent. Several cases of CJD, clinically or histopathologically diagnosed, have been reported in Korea. In order to confirm the diagnosis of CJD and also differential diagnosis of sporadic and familial types of CJD in Korea, we studied two patients who had symptoms of CJD. The histopathological and immunohistochemical studies showed spongiform neurodegeneration and expression of abnormal isoform of prion protein (PrPSc) in astrocytes. Thus, these two patients were diagnosed CJD. To investigate whether these patients were sporadic or familial type of CJD, the molecular analyses of the prion protein gene (PRNP) were done by restriction fragment length polymorphism (RFLP) and DNA sequencing. In the cases of a healthy Korean and two CJD patients, no point mutation was detected in the known hot spots (178, 180, 200, 210, and 232) and they exhibited wild type PRNP sequences. We concluded that both patients have a sporadic type of CJD, but not familial type.

Extensive degeneration of catecholaminergic neurons to scrapie agent 87V in the brains of IM mice

Scrapie is a degenerative disease of the central nervous system of sheep and goats. The causative agent has been passaged to a number of laboratory species, including mice and hamster. Amyloid plaque formation and vacuolation, the signs of senile dementia, are found in the brains of mice infected with 87V scrapie agent. Dopamine (DA) and norepinephrine (NE) concentrations in the brains of scrapie-infected mice were measured with high-performance liquid chromatography-electrochemical detector (HPLC-ECD). A significant decrease in NE level was exhibited in all regions tested, whereas the level of DA decreased significantly only in cerebral cortex. Immunohistochemistry was used to examine immunoreactive catecholamine neurons in substantia nigra and locus ceruleus using antisera against tyrosine hydroxylase (TH). The population of TH-immunoreactive neurons in the substantia nigra and locus ceruleus were significantly decreased in scrapie-infected mice compared to controls. These data suggest that both the noradrenergic and dopaminergic system are sensitive to the action of scrapie agent 87V and that changes in the catecholamine levels in the brains of scrapie-infected mice may contribute to some of the clinical symptoms of the diseases, such as ataxia and apraxia.