Transcriptional squelching by ectopic expression of E2F-1 and p53 is alleviated by proteasome inhibitors MG-132 and lactacystin.

The transcription factors p53 and E2F-1 play important roles in the control of cell cycle progression. In transient transfection experiments, expression of E2F-1, other E2F family members, or p53 squelched transcription from cotransfected plasmids in a dose-dependent manner. Although the proteasome inhibitors MG-132 and lactacystin markedly increased the level of expression of E2F-1 and p53, these inhibitors completely alleviated squelching by both proteins. Several observations indicate MG-132 alleviates squelching by influencing the conformation of newly synthesized p53 and E2F-1:MG-132 increased the fraction of wild type p53 bound by a monoclonal antibody which preferentially recognizes mutant conformers of p53, increased binding of hsp70 to p53 and inhibited nuclear accumulation of both p53 and E2F-1, but not the pocket protein p107. The protease inhibitors ALLN and ALLM did not influence expression of E2F-1 or p53, nor did they alleviate squelching by either transcription factor. Because MG-132 and lactacycstin are highly specific inhibitors of the proteasome protease, our results suggest that the proteasome influences post-translational processes involved in proper folding and cytoplasmic clearing of E2F-1 and p53.

Assessment of noninvasive markers in identifying patients at risk in the Brugada syndrome: insight into risk stratification.

OBJECTIVES: The aim of this study was to compare the use of various noninvasive markers for detecting risk of life-threatening arrhythmic events in patients with Brugada syndrome. BACKGROUND: The role of conduction disturbance in arrhythmogenesis of the syndrome is controversial, whereas it is well established that repolarization abnormalities are responsible for arrhythmias. The value of noninvasive markers reflecting conduction or repolarization abnormalities in identifying patients at risk for significant arrhythmias has not been shown. METHODS: We assessed late potentials (LP) using signal-averaged electrocardiography (ECG), microvolt T-wave alternans (TWA), and corrected QT-interval dispersion (QTD) in 44 consecutive patients who had ECGs showing a pattern of right bundle branch block and ST-segment elevation in leads V1 to V3 but structurally normal hearts. The patients were compared with 30 normal individuals. RESULTS: Eleven patients were excluded from data analysis because of an absence of ECG manifestations of Brugada syndrome at the time of the tests. A history of life-threatening events defined as syncope and aborted sudden death was present in 19 of 33 patients (58%); in 15 of the 19 patients, stimulation induced ventricular fibrillation or polymorphic ventricular tachycardia. The LP were present in 24 of 33 patients (73%); TWA were present in 5 of 31 patients (16%); and a QTD >50 ms was present in 9 of 33 patients (27%). The incidence of LP in Brugada patients was significantly (p < 0.0001) higher than in the controls, whereas incidences of TWA and QTD were not significantly different. Multivariate logistic regression analysis revealed that the presence of LP had the most significant correlation to the occurrence of life-threatening events (p = 0.006). CONCLUSIONS: Late potentials are a noninvasive risk stratifier in patients with Brugada syndrome. These results may support the idea that conduction disturbance per se is arrhythmogenic.

A possible role of prostaglandins in PUVA-induced inflammation: implication by organ cultured skin.

The role of arachidonate metabolites in UV-induced inflammation was analyzed by measuring the amounts of prostaglandins or leukotrienes released into a culture medium in the organ culture of biopsied guinea pig skin following UV exposure. Increased concentrations of prostaglandin E2, F2 alpha, and 6-oxo-F1 alpha were found in the medium subjected to UVB radiation followed by 24 h incubation in the organ culture, compared to medium from non-exposed skin, whereas LTC4 was at an undetectable level in both. This release occurred in UVB dose-dependent fashion and was completely inhibited by the addition of indomethacin to the medium. Exposure to monochromatic UV light of 250, 300, and 350 nm released prostaglandin E2, F2 alpha, and 6-oxo-F1 alpha, in increasing order of 250, 300, and 350 nm, but not LTC4. This order of amount released almost paralleled the intensity of inflammation that occurred with each wavelength. Exposure of skin to UVA following intraperitoneal injection of 8-methoxypsoralen (PUVA) was also found to stimulate the synthesis of prostaglandin E2 in UVA dose-dependent fashion, and the stimulation through an increasing dose of UVA occurred more significantly than UVB exposure. The time course of prostaglandin release following UVB and PUVA exposures was found to have a pattern similar to their dynamics in association with erythema and edema, conditions which could be significantly diminished by the topical application of indomethacin. The present studies demonstrate that prostaglandins play an important role in the production of inflammation by UVB as well as UVA and PUVA.

A prospective study on the effects of early surgery on vasospasm after subarachnoid hemorrhage.

BACKGROUND: To test the hypothesis that early surgery prevents vasospasm, a prospective analysis used strictly selected cases of anterior communicating artery aneurysms with symmetric distribution of subarachnoid hemorrhage. METHODS: Seven patients underwent early surgery (9-29 hours after ictus) through a standard pterional approach. Subarachnoid blood clots surrounding the ipsilateral major cerebral arteries were meticulously irrigated and suctioned. Comparison was made between the hemispheres with surgical intervention and those without, in terms of incidence of delayed ischemic neurologic deficits and cerebral infarction on computed tomographic scans, degree of angiographic vasospasm, and cerebral blood flow (CBF). RESULT: The degree of angiographic vasospasm, quantified by measuring the alterations in the ratio of the diameters of the intracranial arteries (C1, M1) to the extracranial internal carotid artery (C5), did not differ significantly between the surgical and nonsurgical sides. The mean CBF was also comparable between both sides in the chronic spasm phase (Day 6-9) as well as in the early postoperative period (Day 1-3). A significant reduction of CBF was observed during the early postoperative period in the basal frontal lobe of the surgical side. This CBF reduction seems to correspond to brain retraction. CONCLUSIONS: The results suggest that the effect of clot removal may be offset by the negative aspect of early surgery, and early surgery per se seems to have little effect on the course of the chronic vasospasm.

[A distal posterior inferior cerebellar artery aneurysm in the fourth ventricle: a case report].

The authors reported a case of a fourth ventricle aneurysm originating from the choroidal branch of the posterior inferior cerebellar artery (PICA). A 65-year-old woman became comatose following the acute onset of a severe headache and vomiting. She was moribund on admission, showing decerebrate posture. CT scan revealed a massive hematoma in the fourth ventricle up to the lateral ventricle. Extension of blood to the cisterna magna through the cerebellar vermis was also noted. Angiography demonstrated an aneurysm distally located on the right PICA across the midline. The aneurysm lodged in the choroid plexus which was exclusively fed by the right PICA was excised without difficulty through suboccipital craniectomy. Postoperative course was uneventful. She regained her full consciousness by two days after the operation, and was discharged with a minimal truncal ataxia. To our knowledge, this is the first report of a ruptured aneurysm developing in the choroid plexus of the fourth ventricle. Hemodynamic stress is speculated to be a causative factor of such a lesion.

[Preexisting seizure was enhanced under general anesthesia in a AVM patient].

A 21-year-old patient with right basal ganglial AVM was scheduled twice for cranioplasty under general anesthesia (nitrous oxide oxygen isoflurane anesthesia and modified neurolept anesthesia), after a surgery for removal of hematoma from the AVM three months previously. After this operation and before anesthesia for cranioplasties, he showed tremor-like seizure around the left arm and leg about once a day. During anesthesia for cranioplasties, he developed the similar and enhanced seizure frequently in response to intravenous injections of thiopental and midazolam, needle injections into the skin, intratracheal as well as oral suctions and other stimuli. The reason of decreased cerebral perfusion is probably due to the previous operation and administrations of thiopental and midazolam. Because of decreased perfusion around this cerebral lesion, concentrations of the anesthetics might have remained low around the lesion under general anesthesia. Therefore, the resulting hypoxia and prolonged light anesthesia in the basal ganglia, might have enhanced the seizure.

[Effects of oral flecainide treatment of refractory tachyarrhythmias].

Oral flecainide treatment was given to five patients who were refractory to conventional antiarrhythmic agents. The five patients included one with atrioventricular reentrant tachycardia (AVRT), one with non-sustained ventricular tachycardia (nsVT) and three with sustained VT (sVT). Flecainide produced favorable responses in patients of AVRT, nsVT and sVT with arrhythmogenic right ventricular dysplasia (ARVD). In the case of AVRT, flecainide exhibited a preventive effect on tachycardia induced by programmed electrical stimulation (PES). In the case of nsVT, flecainide markedly reduced the number of VPC and abolished the VT on the Holter ECG. In the case of sVT with ARVD, sVT was not induced by PES after the flecainide. Long-term treatment with flecainide on these three cases produced complete prevention of tachycardias. As an adverse effect of flecainide, an aggravation of congestive heart failure was recognized in one case with cardiac sarcoidosis. PQ interval and QRS interval in all the cases were prolonged after flecainide. The results indicate that flecainide is a useful antiarrhythmic agent for tachyarrhythmias refractory to treatment with conventional drugs.

Permeability to solutes of polyamide capsules with different chemical compositions.

The permeability of nylon capsule membranes with different chemical compositions to solutes was studied at different temperatures. The rate of solute permeation through the membrane decreased with increasing hydrophobicity of the membrane in the temperature range of 293-323 K. Increase in the size of permeant molecules caused a decreased in their rate of permeation through all capsule membranes at all temperatures studied. Higher permeation rates were observed for all permeants at higher temperatures. The activation energy of permeation was evaluated for the permeants from the Arrhenius plots of their permeation data. From the values of activation energy evaluated the solute permeation through the nylon capsule membranes was demonstrated to proceed by a pore mechanism.

Double ventricular responses to a single atrial depolarization in a patient with dual AV nodal pathways.

Electrophysiological study was performed in a patient with atrioventricular nodal reentrant tachycardia (AVNRT). Double ventricular responses through dual AV nodal pathways were observed by atrial extrastimulus technique followed by initiation of AVNRT. The difference in conduction time between the slow and fast AV nodal pathways was longer than 320 msec. A ventricular extrastimulus delivered during sinus rhythm, which was not followed by ventriculoatrial conduction, also induced AVNRT. These findings indicated the presence of an antegrade critical delay and retrograde block in the slow AV nodal pathway, criteria necessary for the occurrence of a double ventricular response.

Association of humps on monophasic action potentials and ST-T alternans in a patient with Romano-Ward syndrome.

A case of Romano-Ward syndrome had episodes of torsade de pointes preceded by ST-T alternans. ST-T alternans was induced by isoproterenol and abolished by verapamil, lidocaine, mexiletine and MgSO4. A monophasic action potential (MAP) showed humps in MAPs at the right ventricular outflow tract but not at the right ventricular apex in alternate beats. Differences in the MAP duration were noted between the two areas and were associated with ST-T alternans. Atrial pacing abolished both humps and ST-T alternans. These results suggest that humps are a possible reflection of early afterdepolarizations and their appearance is limited to localized regions of the ventricles, which produces regional disparity of repolarization and ST-T alternans.

Significance of abnormal root mean square voltages in signal averaged electrocardiogram as a reliable predictor of sustained ventricular tachycardia.

The late potential is useful to predict patients with sustained ventricular tachycardia (VT). However, because positive predictive value for sustained VT is low, the validity of late potential for screening the patients to be studied by electrophysiological tests was not high. We examined 923 cases, including 63 cases of sustained VT. When we separated patients showing abnormal values of the root mean square voltage of the QRS end part 40 milliseconds (RMS40) into four groups, there was a tendency of a higher incidence of sustained VT with lower value of RMS40. When we conducted electrophysiological tests on 121 cases without sustained VT, it turned out a high induction rate of sustained VT in patients with low RMS40 values (RMS40 < 10 microV, 67%; < 20 microV, 30%; 20 microV, < or = 5%). We conclude abnormally low value (less than 10 microV) of RMS40 can be useful for screening the late potential-positive cases who are high risk for inducible sustained VT.

Immunocytochemical investigation of atherosclerotic changes observed in aortocoronary bypass vein grafts using monoclonal antibodies.

The authors have performed immunocytochemical surveys on atherosclerotic changes observed in saphenous vein aortocoronary bypass grafts, comparing the changes occurring in coronary and aortic lesions. The two monoclonal antibodies used in this study were obtained by T. Tsukada. One of them, named HHF35, exhibited specificity to smooth muscle cells; the other, named HAM56, was specific to macrophages. These immunocytochemical studies clearly demonstrated that cells encountered within the fibrous intimal thickening in the vein graft were inevitably smooth muscle cell in origin. Macrophages were seldom seen in the grafts examined. In contrast to vein grafts, macrophages were noted within the intima of all specimens from arterial atherosclerotic lesions obtained from the same patients. These studies suggest a difference in the progression of intimal thickening between the venous graft and the arterial atherosclerotic lesions.

[Transient obstruction of the left ventricular outflow tract induced by excessive alcohol intake: a case report].

A case of transient obstruction of the left ventricular outflow tract after excessive intake of alcohol was reported. This 41-year-old man was admitted to the Hiroo Hospital because of a syncopal attack experienced while walking. He had been drinking excessively for one week until the day before admission. On admission, physical examination revealed a bifid carotid pulse and a grade 3/6 systolic ejection murmur accentuated by Valsalva maneuvers and prompt standing. The second heart sound was paradoxically split. Echocardiography showed typical systolic anterior motion of the mitral valve (SAM). The interventricular septal and left ventricular posterior wall thicknesses were 13 mm and 11 mm, respectively. No enlargement or displacement of the papillary muscles was noted. The redundant mitral chordae tendineae protruded into the left ventricular outflow tract in systole, and both the anterior and posterior mitral valve leaflets were retracted upwards approximating the interventricular septum by these chordae, resulting in obstruction of the left ventricular outflow tract. All signs of left ventricular outflow obstruction, including SAM, disappeared within several days after admission, and prolapse of the anterior mitral leaflet became evident. Since ejection fraction was markedly increased and the corrected QT interval was prolonged on admission, this patient was considered to be in hyperadrenergic state induced by excessive alcohol intake. In this case, left ventricular outflow tract obstruction was attributed to hyperadrenergic state and a redundant mitral apparatus.

Proliferative potential and malignant transformation of ganglioglioma: immunohistochemical studies by MIB-1 and p53 staining.

We studied two cases of ganglioglioma immunohistochemically by MIB-1 and p53 staining. The positive rate of MIB-1 in the ganglionic cells was 5.5% in Case 1 and 7.8% in Case 2, and that of MIB-1 in the gliomatous cells was 1.4 and 6.6% respectively. The labeling index of p53 in the ganglionic cells was 7.3% in Case 1 and 7.7% in Case 2, and that of the gliomatous cells was 1.9 and 3.4% respectively. MIB-1 and p53 did not stain ganglionic precursor cells. These results indicate that the ganglionic cells also take part in proliferation and have potential of malignant transformation.

[Tricuspid and mitral regurgitation due to congenital hypoplasia of atrioventricular valves in the aged: a case report].

A 76-year-old woman with a history of repeated right-sided cardiac failure during the past 2 years presented with tricuspid and mitral regurgitation due to congenital hypoplasia of atrioventricular valves. Two-dimensional echocardiography demonstrated enlarged right atrium and right ventricle, and discoaptation between the leaflets. Color Doppler echocardiography revealed severe tricuspid regurgitation through the gap between the leaflets. Autopsy showed congenital hypoplasia of the leaflets and the chordae tendineae in the tricuspid and mitral valvular apparatus.

[Lassa fever associated with effusive constrictive pericarditis and bilateral atrioventricular annular constriction: a case report].

A case of Lassa fever associated with effusive constrictive pericarditis and bilateral atrioventricular annular constriction was reported. A 49-year-old man, who had been diagnosed by indirect fluorescent antibody test as the first case of Lassa fever in Japan, was referred to the Hiroo Hospital because of syncope, progressive hepatomegaly, ascites and pericardial effusion in spite of pericardiocentesis and corticosteroid therapy. On admission, his blood pressure was 92/60 mmHg and he had a paradoxical pulse. Two-dimensional echocardiography revealed a localized pericardial effusion adjacent to the right ventricular wall and behind the left ventricular posterior wall. Bilateral atrioventricular annular constriction was also present. On pulsed Doppler echocardiography, the peak inflow velocities of the right and left ventricles increased during atrial systole. Right heart catheterization revealed a mean diastolic pressure gradient of 8 mmHg across the tricuspid valve. After pericardiectomy, a diastolic dip and plateau pattern became evident in the right ventricular pressure tracing, suggesting the presence of residual constriction. However, the atrioventricular annular constriction was no longer evident on two-dimensional echocardiography. This is considered the first reported case of subacute effusive constrictive pericarditis caused by Lassa fever.

mdm2 and bax, downstream mediators of the p53 response, are degraded by the ubiquitin-proteasome pathway.

Upon activation in response to cellular stress or DNA damage, the p53 tumor suppressor induces the expression of gene products involved in cell cycle arrest and apoptosis. Using the proteasome-specific inhibitors, MG132 (N-acetyl-L-leucinyl-L-leucinal-L-leucinal) and lactacystin, here we show that the p53-response proteins, bax and mdm2 as well as p21, are degraded by the ubiquitin-proteasome pathway in HeLa cells. MG132 also increased expression of the three proteins in cells that lack p53, showing that stabilization of the p53 response proteins is not due to increased levels of p53 itself. Increases in mdm2 protein levels by MG132 was accompanied by increases in polyubiquitinated forms of the proteins. Our results indicate that ubiquitin-dependent protein degradation influences the turnover of downstream targets of p53, therefore suggesting that the proteasome plays a role in regulating apoptosis and cell cycle arrest in response to p53.