The Appearance and Destruction of Platelet-Clumping Substance in Serum Added with Trypsin

No platelet-clumping activity was detected in the serum collected from 10 rabbits. After incubation of the alkalinized serum for 2 to 4 min at 37° C with 1.6 or 3.2 mg/ml of trypsin, platelet-clumping activity was observed in all samples. The strongest response was observed in the serum incubated for 4 min with 3.2 mg/ml of trypsin. After incubation for over 8 min, the clumping activity decreased gradually. At any incubation time, the serum without trypsin or with 0.4 or 6.4 mg/ml of trypsin showed no clumping activity. After the above measurements of the activity, 100 u/ml of heparin was added to the serum and its pH value was adjusted to 5.6. In the serum without trypsin the clumping activity appeared. However, in the active serum with trypsin, the activity remained the same or decreased. The serum acidified to pH 5.6 with heparin, which showed platelet-clumping activity, was incubated at 37° C with 1.6, 3.2 or 6.4 mg/ml of trypsin. After incubation of the serum with 3.2 mg/ml of trypsin for 16 min, the activity was markedly reduced. After incubation with 6.4 mg/ml of trypsin for 2 min, the activity disappeared. After incubation with trypsin, the clumping activity was observed in BaSO4-adsorbed serum but was not observed in serum heated at 56° C for 1 min nor in serum to which EDTA was added in a final concentration of 0.1%. These results suggest that the precursor of the platelet-clumping substance was activated by trypsin, and the platelet-clumping substance and/or its precursor was destroyed by trypsin.

Crystal Engineering of Self-Assembled Porous Protein Materials in Living Cells

Crystalline porous materials have been investigated for development of important applications in molecular storage, separations, and catalysis. The potential of protein crystals is increasing as they become better understood. Protein crystals have been regarded as porous materials because they present highly ordered 3D arrangements of protein molecules with high porosity and wide range of pore sizes. However, it remains difficult to functionalize protein crystals in living cells. Here, we report that polyhedra, a natural crystalline protein assembly of polyhedrin monomer (PhM) produced in insect cells infected by cypovirus, can be engineered to extend porous networks by deleting selected amino acid residues located on the intermolecular contact region of PhM. The adsorption rates and quantities of fluorescent dyes stored within the mutant crystals are increased relative to those of the wild-type polyhedra crystal (WTPhC) under both in vitro and in vivo conditions. These results provide a strategy for designing self-assembled protein materials with applications in molecular recognition and storage of exogenous substances in living cell as well as an entry point for development of bioorthogonal chemistry and in vivo crystal structure analysis.

Design of Enzyme-Encapsulated Protein Containers by In Vivo Crystal Engineering

Crystalline protein assemblies of polyhedra crystal (PhC) can be utilized as solid enzyme containers for long-term storage of enzymes with retention of their enzymatic activity. The enzymes can be released from the crystals at the optimum pH for the enzymatic activity by dissolution of the crystals using in vivo crystal engineering.

Cell proliferation by silk gut incorporating FGF-2 protein microcrystals

Silk gut processed from the silk glands of the silkworm could be an ideal biodegradable carrier for cell growth factors. We previously demonstrated that polyhedra, microcrystals of Cypovirus 1 polyhedrin, can serve as versatile carrier proteins. Here, we report the generation of a transgenic silkworm that expresses polyhedrin together with human basic fibroblast growth factor (FGF-2) in its posterior silk glands to utilize silk gut as a proteinaceous carrier to protect and slowly release active cell growth factors. In the posterior silk glands, polyhedrin formed polyhedral microcrystals, and FGF-2 became encapsulated within the polyhedra due to a polyhedron-immobilization signal. Silk gut powder prepared from posterior silk glands containing polyhedron-encapsulated FGF-2 stimulated the phosphorylation of p44/p42 MAP kinase and induced the proliferation of serum-starved NIH3T3 cells by releasing bioactive FGF-2. Even after a one-week incubation at 25 °C, significantly higher biological activity of FGF-2 was observed for silk gut powder incorporating polyhedron-encapsulated FGF-2 relative to silk gut powder with non-encapsulated FGF-2. Our results demonstrate that posterior silk glands incorporating polyhedron-encapsulated FGF-2 are applicable to the preparation of biodegradable silk gut, which can protect and release FGF-2 that is produced in a virus- and serum-free expression system with significant application potential.

Bombyx mori nucleopolyhedrovirus nucleic acid binding proteins BRO-B and BRO-E associate with host T-cell intracellular antigen 1 homologue BmTRN-1 to influence protein synthesis during infection

Previous reports have indicated that the Bombyx mori nucleopolyhedrovirus (BmNPV) nucleic acid binding proteins BRO-B and BRO-E are expressed during the early stage of infection and that the BRO family likely supports the regulation of mRNA; however, no study has directly examined the function of BRO family proteins in virus-permissive cells. Here, we show that BRO-B and BRO-E associate with cellular T-cell intracellular antigen 1 homologue (BmTRN-1), a translational regulator, and other cellular translation-related proteins in silkworm cells during viral infection. We created BM-N cells that expressed BRO-B/E to study molecular interactions between BmTRN-1 and BRO-B/E and how they influenced protein synthesis. Fluorescent microscopy revealed that BmTRN-1 was localized in cytoplasmic foci during BmNPV infection. Immunofluorescence studies confirmed that BmTRN-1 and BRO-B/E were colocalized in the amorphous conspicuous cytoplasmic foci. Reporter gene studies revealed that co-expression of BRO-B/E synergistically led to a significant decrease in protein synthesis from a designed transcript carrying the 5'untranslated region of a cellular mRNA with no significant change of transcript abundance. Additionally, RNA interference-mediated knockdown of BmTRN-1 resulted in a marked inhibition of the ability of BRO-B/E to regulate the transcript. These results suggested that the association of BmTRN-1 with BRO-B/E is responsible for the inhibitory regulation of certain mRNAs at the post-transcriptional level and add an additional mechanism for how baculoviruses control protein synthesis during infection.

Fibroblast growth factor-2 is an important factor that maintains cellular immaturity and contributes to aggressiveness of osteosarcoma

Osteosarcoma is the most frequent, nonhematopoietic, primary malignant tumor of bone. Histopathologically, osteosarcoma is characterized by complex mixtures of different cell types with bone formation. The role of environmental factors in the formation of such a complicated tissue structure as osteosarcoma remains to be elucidated. Here, a newly established murine osteosarcoma model was used to clarify the roles of environmental factors such as fibroblast growth factor-2 (Fgf2) or leukemia-inhibitory factor (Lif) in the maintenance of osteosarcoma cells in an immature state. These factors were highly expressed in tumor environmental stromal cells, rather than in osteosarcoma cells, and they potently suppressed osteogenic differentiation of osteosarcoma cells in vitro and in vivo. Further investigation revealed that the hyperactivation of extracellular signal-regulated kinase (Erk)1/2 induced by these factors affected in the process of osteosarcoma differentiation. In addition, Fgf2 enhanced both proliferation and migratory activity of osteosarcoma cells and modulated the sensitivity of cells to an anticancer drug. The results of the present study suggest that the histology of osteosarcoma tumors which consist of immature tumor cells and pathologic bone formations could be generated dependent on the distribution of such environmental factors. The combined blockade of the signaling pathways of several growth factors, including Fgf2, might be useful in controlling the aggressiveness of osteosarcoma.

The use of leukemia inhibitory factor immobilized on virus-derived polyhedra to support the proliferation of mouse embryonic and induced pluripotent stem cells

Human leukemia inhibitory factor (LIF) was immobilized into insect virus-derived microcrystals (polyhedra) to generate LIF polyhedra (LIF-PH) that can slowly release LIF into embryonic stem (ES) cell culture media and thus maintain ES cells in an undifferentiated state. Assays of the biological activities of LIF-PH indicated that a single addition of LIF-PH to the ES cell culture medium can support the proliferation of mouse ES and induced pluripotent stem (iPS) cells continuously for 14 days, and suggest that LIF-PH can be successfully used in the place of a periodic addition of recombinant LIF to the media every 2-3 days. The release of LIF protein from LIF-PH was determined by enzyme-linked immunosorbent assay (ELISA). Maintenance of undifferentiated state of mouse ES and iPS cells cultured with LIF-PH was determined by the detection of pluripotency-related biomarkers Oct3/4 and stage-specific embryonic antigen-1 (SSEA-1) through immunostaining and measurement of alkaline phosphatase activity. In this paper, we propose a closed culture system for mass production of ES and iPS cells that utilize a slow-releasing agent of LIF.

Structure-based targeting of bioactive proteins into cypovirus polyhedra and application to immobilized cytokines for mammalian cell culture

Certain insect viruses produce stable infectious micro-crystals called polyhedra which function to protect the virus after the death of infected larvae. Polyhedra form within infected cells and contain numerous virus particles embedded in a crystalline lattice of the viral protein polyhedrin. We have previously demonstrated that the N-terminal 75 amino acids of the Bombx mori cypovirus (BmCPV) turret protein (VP3) can function as a polyhedrin recognition signal leading to the incorporation of foreign proteins into polyhedra. Foreign proteins tagged with the VP3 polyhedrin recognition signal were incorporated into polyhedra by co-expression with polyhedrin in insect cells. We have used this method to encapsulate a wide variety of foreign proteins into polyhedra. The atomic structure of BmCPV polyhedrin showed that the N-terminal H1 alpha-helix of polyhedrin plays a significant role in cross-linking and stabilizing polyhedra. Here we show that the polyhedrin H1-helix can also function as a polyhedrin recognition signal and can be used like the VP3 N-terminal sequence to target foreign proteins into polyhedra. In addition, the two targeting methods can be used together to produce polyhedra containing both EGFP and Discosoma sp. Red Fluorescent Protein (DsRed). The modified polyhedra were imaged using dual-wavelength confocal microscopy showing that the two foreign proteins are uniformly incorporated into polyhedra at similar levels. We have investigated the biological and physiological properties of fibroblast growth factor-2 (FGF-2), FGF-7 and epidermal growth factor (EGF) immobilized on polyhedra with either the H1 or the VP3 tag. Growth factors produced by both methods were functional, inducing the growth of fibroblast cells and keratinocytes. The results demonstrate the utility and flexibility of modified polyhedra for encapsulating and stabilizing bioactive proteins.

Restored atrial excitability after late recanalization in a patient with atrial standstill and acute myocardial infarction

Atrial standstill is electrophysiologically characterized by the loss of spontaneous excitation in atrial muscle and the inability to cause action potential firing upon electrical stimulation. Clinical diagnosis of transient standstill of the right atrium was made in a patient with acute occlusion of the right coronary artery and acute renal failure. Percutaneous coronary intervention, performed 5 days after the onset, restored the coronary blood flow and resulted in full recovery of electrical activity and regular sinus rhythm.

Systemic circulatory parameters. comparison between patients with normal tension glaucoma and normal subjects using ambulatory monitoring

PURPOSE

To compare circadian changes of systemic circulation in patients with normal tension glaucoma (NTG) and normal subjects.

METHODS

Forty-three patients with NTG and 226 normal subjects were enrolled in this study. Circulatory parameters, including blood pressure (BP) and pulse rate (PR), were measured in all subjects for 49 hours using an ambulatory monitoring system. In addition to a comparison between NTG patients and normal controls, the same parameters were compared between NTG patients who had progressive field defects and NTG patients who had stable field defects.

RESULTS

The BP in NTG patients was significantly higher than in normal subjects. The nocturnal dip of BP in NTG patients was similar to the dip in normal subjects. However, the BP dip in NTG patients showing progressive visual field defects was significantly smaller than in patients with NTG showing stable visual field defects. Blood pressure fluctuation in sleep in the "progressive" patients was significantly greater than in the "stable" patients. Patients with NTG whose random BP was in a normal range showed a higher BP than normal subjects. The dip in PR in NTG patients was significantly lower than in normal subjects.

CONCLUSIONS

An insufficient physiological nocturnal BP dip or a greater nocturnal fluctuation in BP may disturb the microcirculation of, and/or may directly damage, the optic nerve, resulting in increasing field loss in NTG.

Changes in plasma atrial natriuretic peptide after angiocardiography

BACKGROUND

Angiocardiography is an important diagnostic modality for evaluation of heart disease. It is well known that the concentration of plasma atrial natriuretic peptide (ANP) increases after injection of contrast medium. On the other hand, some patients with hypertension, heart failure or cardiac hypertrophy have an increased plasma ANP concentration at baseline; however, whether ANP increases after angiography in these patients is unknown.

OBJECTIVES

To investigate changes in plasma ANP concentrations after angiocardiography in patients with high ANP concentrations at baseline.

PATIENTS AND METHODS

Plasma ANP concentrations of 32 patients with angina pectoris were measured before and after angiocardiography. They were then classified into two groups according to their ANP concentration before examination.

RESULTS

ANP concentration after the injection of contrast medium increased significantly in patients with normal ANP concentrations before angiography but did not change in patients with high ANP concentrations at rest.

CONCLUSIONS

These results suggest that the absence of an increase in ANP after angiography may in part be due to reduced sensitivity to the angiography stimulus or to an already maximal activation of ANP secretion at baseline.

Successfully Treated Unstable Angina Pectoris in a Young Japanese Female

A 25-year-old Japanese female complaining chest oppression and palpitation was admitted to hospital under the presumptive diagnosis of ischemic heart disease (IHD), although no obvious underlying disease associated with IHD was detected. Coronary angiography showed stenosis at the proximal site of left anterior descending artery (LAD), with dilatation and tortuosity at the bifurcation of the first and the second septal branches. Intravascular ultrasound imaging of the LAD showed intimal thickness without calcification at the site of stenosis. The stenosis was successfully and smoothly dilated by percutaneous transluminal angioplasty. Even with precise evaluation, the cause of the coronary artery disease in this young female patient was not clarified. Further careful follow-up is needed.

Improvement of exercise tolerance by single lead VDD pacemaker: evaluation using cardiopulmonary exercise test

We used a cardiopulmonary test to assess the physiological benefit of single lead VDD pacing in ten patients (six men, four women; aged 32-84 years, mean 69 years) with atrioventricular block. Maximal symptom-limited treadmill exercise test using a ramp protocol was performed under VDD and VVIR or VVI pacing (VVI) in random sequence. The pacemaker was then programmed to the VDD mode, and Holter ECG was recorded in nine patients. Compared with findings during the VVI, the VDD mode had a greater chronotropic response (mean maximal heart rate, VDD 106 +/- 17 beats/min vs VVI 79 +/- 19 beats/min, P = 0.03), and was associated with prolongation of exercise duration (VDD 11.2 +/- 2.9 minute vs VVI 10.5 +/- 3.1 minute; P = 0.01), and the onset of anaerobic threshold at a higher oxygen uptake (VDD 12.4 +/- 3.4 mL/min per kilogram vs VVI 10.0 +/- 2.1 mL/min per kilogram; P < 0.01). Atrial sensing was recognized in almost all normal sinus P waves for all cases examined using Holter ECG. Thus, chronotropic response during exercise by VDD pacemaker improved exercise tolerance, indicating that a VDD pacemaker might be useful for patients requiring physical activity.

Hypertrophic cardiomyopathy complicated with cardiac amyloidosis

The echocardiographic findings of hypertrophic cardiomyopathy (HCM) are very similar to those of cardiac amyloidosis. A 76-year-old Japanese man was admitted for treatment of early stage gastric cancer in July 1996. His electrocardiogram indicated left ventricular hypertrophy and echocardiography showed left ventricular hypertrophy with asymmetric septal hypertrophy. He was re-admitted complaining of dyspnea on effort and pretibial edema in October 1998. The amplitude of QRS complex on electrocardiogram was decreased. Echocardiogram showed left ventricular wall thickening with granular sparkling. He was diagnosed as HCM with cardiac amyloidosis.

Cardiac arrhythmias and left ventricular hypertrophy in dipper and nondipper patients with essential hypertension

To evaluate the behavior of cardiac arrhythmias in dipper and nondipper hypertensive patients, 48-h ambulatory blood pressure monitoring, 24-h Holter electrocardiogram recording and echocardiographic studies were performed in 56 untreated outpatients with essential hypertension. These patients were divided into 2 groups according to the presence (dipper, n=33) or absence (nondipper, n=23) of reduction of both systolic and diastolic blood pressure during nighttime by an average of more than 10% of daytime blood pressure. Mean 48-h systolic and diastolic blood pressures did not differ between the 2 groups. Nondipper patients had a significantly larger left atrial dimension (31.9+/-3.8 vs 35.6+/-3.7 mm; p<0.01), left ventricular mass index (114+/-26 vs 136+/-36 g/m2; p<0.05), as well as a larger number of total supraventricular (16+/-19 vs 89+/-197 beats; p<0.05) and ventricular ectopic beats (7+/-14 vs 47+/-96 beats; p<0.05) during daytime as compared with dippers. In conclusion, nondipper hypertensive patients are likely to experience supraventricular and ventricular arrhythmias more frequently than dippers. A blunted nocturnal blood pressure fall may be involved in the appearance of cardiac arrhythmias in patients with essential hypertension.

Circadian rhythm of autonomic nervous function in patients with normal-tension glaucoma compared with normal subjects using ambulatory electrocardiography

PURPOSE

To compare circadian rhythm of autonomic nervous function in patients with normal-tension glaucoma with subjects with normal eyes.

METHODS

Thirty-two patients with normal-tension glaucoma and 32 age-matched normal subjects who had no history of systemic disorders and no currently treated systemic disorders, especially diseases of the autonomic nervous system, were studied. An ambulatory electrocardiogram was installed that recorded heartbeats for 48 hours. Low-frequency and high-frequency values were calculated as markers of the autonomic nervous system status based on heart-rate variability using a power-spectrum analysis.

RESULTS

The low-frequency values of patients with normal-tension glaucoma during the spans of an active day and a resting night were significantly greater than those of normal subjects, and this difference was emphasized during the night resting span. However, the high-frequency values of patients with normal-tension glaucoma were similar to those of normal subjects. The normal subjects showed a significant age-related decrease in all investigated parameters except the low-frequency values during the resting span. However, the patients with normal-tension glaucoma showed a significant age-related decrease only in low-frequency values during the active day. Patients with normal-tension glaucoma with progressive visual field defects showed much greater values than other cases, although the values were not significantly different.

CONCLUSION

These results indicate that a disturbance of the circadian rhythm of the autonomic nervous system may exist in patients with normal-tension glaucoma.

Pathological findings of the isthmus between the inferior vena cava and tricuspid annulus ablated by radiofrequency application

Anatomically guided radiofrequency ablation for the treatment of atrial flutter was performed in a 41-year-old man with interstitial pneumonia. He died of respiratory failure 2 months after ablation, and an autopsy was performed. The whole layer of the ablation site showed a transluminal fibrosis.

The inhibitory effects of carvedilol against arrhythmias induced by coronary reperfusion in anesthetized rats

BACKGROUND

Previous study has shown the antiarrhythmic effects of carvedilol on isolated rat hearts, but little is known about the mechanism of this protective action. This article examines the inhibitory effect of carvedilol against arrhythmias induced by reperfusion in anesthetized rats. In addition, the results are compared with those with propranolol, superoxide dismutase (SOD) plus catalase, and a combination of both in order to elucidate the mechanism of the protective actions.

METHODS AND MATERIALS

Ninety percent of the rats in the control group showed lethal ventricular fibrillation (VF). Carvedilol at the doses of 0.03, 0.1, and 0.3 mg/kg significantly reduced the incidence of lethal VF to 0%, 0%, and 10%, respectively (P <.05). In contrast, propranolol at the doses of 0.3, 1.0, and 3.0 mg/kg and SOD (35,000 units/kg) plus catalase (400,000 units/kg) did not reduce the incidence of lethal VF (80%, 60%, 70%, and 70%, respectively). However, administration of a combination of propranolol (1.0 mg/kg) and SOD plus catalase completely inhibited the occurrence of lethal VF to 0% (P<.05).

CONCLUSION

These results indicate that carvedilol has the inhibitory effect against reperfusion arrhythmias in rats and suggest that the mechanism of action of this compound is related to the combined effects of beta-blocking and antioxidant.

Successfully treated complete atrioventricular block with corticosteroid in a patient with cardiac sarcoidosis: usefulness of gallium-67 and thallium-201 scintigraphy

A 71-year-old male with sarcoidosis was followed for 6 years without steroid therapy. He was admitted because of complete atrioventricular block. Chest X-ray showed hilar lymphadenopathy. Echocardiogram showed mild left ventricular hypertrophy without local wall thinning. Cardiac sarcoidosis was diagnosed by a defect of Thallium-201 (Tl-201) imaging and abnormal uptake of Gallium-67 (Ga-67). After the start of corticosteroid therapy, complete atrioventricular block was recovered. Abnormal uptake of Ga-67 was improved. Tl-201 and Ga-67 are useful to diagnose cardiac sarcoidosis, to evaluate the lesion of cardiac involvement and to estimate the efficacy of corticosteroid therapy.

Effect of imidapril in dipper and nondipper hypertensive patients: comparison between morning and evening administration

The purpose of the study was to identify differences in the patterns of efficacy and duration of effects of imidapril administered at different times of the day (morning versus evening) in dipper and nondipper hypertensive patients. Twenty patients with untreated hypertension were classified into two groups: dippers (n = 9) and nondippers (n = 11). Imidapril (10 mg) was given at 07:00 or 18:00 for 4 weeks in a crossover fashion. Blood pressure (BP) and heart rate (HR) were monitored before and after morning and evening treatment every 30 min for 48h by ambulatory BP monitoring (ABPM). In dipper hypertension, the mean 48h BP was reduced with both doses. The decrease in the diurnal BP was stronger when the drug was administered in the evening than morning, but without significant difference. In nondipper hypertension, the systolic BP decreased at night with both doses, but the extent of the nocturnal reduction in systolic BP was greater after morning therapy. There were no significant differences in the decrease in BP during the day or night between the morning and evening administrations. When imidapril was administered in the morning, its serum concentration reached a maximum at 16:00, and when the drug was administered in the evening, it reached a maximum at 6:00. In dipper hypertension, the time taken for the blood concentration of imidapril to reach a maximum changed depending on its time of administration, and the time when the maximum antihypertensive effect of the drug appeared was different. In nondipper hypertension, decreases in the BP were confirmed at night regardless of the time of administration; this might be caused by angiotensin converting enzyme (ACE) inhibitors effectively blocking the BP from increasing by activating the parasympathetic nervous system. Therefore, when assessing the effectiveness of antihypertensive agents, factors such as the various patterns of BP before therapy and administration time must be considered.

Relation between QT interval dispersion and heart rate

Because the relation between QT dispersion (QTd) and heart rate (HR) are different from that between QT interval and HR, QTd could be overadjusted at a high HR and be underadjusted at a slow HR if we use Bazett's formula to adjust QTd. HR adjustment of QTd is not needed to evaluate repolarization dispersion.

Antiarrhythmic effect of magnesium sulfate against occlusion-induced arrhythmias and reperfusion-induced arrhythmias in anesthetized rats

The antiarrhythmic effect of magnesium sulfate (Mg) as well as the hemodynamics were studied using the coronary ligation and reperfusion models in rats. In the study on coronary ligation arrhythmia, i.v. administration of Mg (0.6, 2, 6, 20 and 60 micromol) was conducted at 5 min after coronary ligation. Mg had an action to decrease the total number of premature ventricular contraction (PVC), the duration of ventricular tachycardia (VT), the frequency of VT and ventricular fibrillation (Vf) and the mortality ratio for 30 min after coronary ligation. In the 6-60 micromol groups, significant antiarrhythmic action (p < 0.01 vs. control) was attained. In the study on reperfusion arrhythmia, i.v. administration of Mg (20, 60 and 200 micromol) was conducted at 4 min after coronary ligation, and at 1 min after ligation, the coronary artery was reperfused. Mg had an action to decrease the frequency of Vf, the mortality ratio and the duration of VT and Vf and to extend the interval between the initiation of reperfusion and the occurrence of VT and Vf for 10 min after reperfusion. In the 200 micromol group, significant antiarrhythmic action (p < 0.05 vs. control) was attained. Administration of Mg decreased the heart rate and blood pressure. We concluded that Mg can control myocardial ischemia-induced and reperfusion-induced arrhythmia and that sudden cardiac death which occurs as a result of arrhythmia can be prevented.

Exercise-induced uncommon atrioventricular nodal reentrant tachycardia with sick sinus syndrome: a case report

Exercise seldom provokes tachycardia in patients with paroxysmal supraventricular tachycardia (PSVT). This report presents a case of exercise-induced uncommon atrioventricular nodal reentrant tachycardia (AVNRT) with sick sinus syndrome. Treadmill exercise testing provoked AVNRT of long RP' with good reproducibility. Uncommon AVNRT was confirmed by the lack of atrial pre-excitation during PSVT and para-Hisian pacing. The patient has been successfully treated with verapamil and DDD pacing for 5 years.

Alterations of autonomic nervous activity in recurrence of variant angina

OBJECTIVE

To investigate whether autonomic nervous activity is involved in the recurrence of spontaneous coronary spasm in variant angina.

DESIGN

Retrospective analysis.

SETTING

Cardiology department of a university hospital.

PATIENTS

18 patients with variant angina were divided into single attack group (SA; nine patients) and multiple attack group (MA; nine patients) according to the frequency of ischaemic episodes with ST segment elevation during 24 hour Holter monitoring.

METHODS

Heart rate variability indices were calculated using MemCalc method, which is a combination of the maximum entropy method for spectral analysis and the non-linear least squares method for fitting analysis, at 30 second intervals for 30 second periods, from 40 minutes before the attack to 30 minutes after the attack. High frequency (HF; 0.04-0.15 Hz) was defined as a marker of parasympathetic activity, and the ratio of low frequency (LF; 0.15-0.40 Hz) to high frequency (LF/HF) as an indicator of sympathetic activity. The averaged value during the 40 to 30 minute period before an attack was defined as the baseline.

RESULTS

Compared with baseline, the HF component decreased in both groups at two minutes before the attack (p < 0.01), and the LF/HF ratio decreased at three minutes before the attack (p < 0.01). The baseline LF/HF was lower in the MA group than in the SA group (p < 0. 01).

CONCLUSIONS

A reduction of sympathetic activity may play a key role in determining the recurrence of transient ischaemic events caused by spontaneous coronary spasm in patients with variant angina.

[Differences in exercise blood pressure response between dipper and non-dipper elderly patients with essential hypertension]

We evaluated the circadian variation and exercise stress response patterns of blood pressure (BP) in elderly patients with essential hypertension. Ambulatory BP monitoring for 48 hours every 30 minutes, and treadmill exercise test using a Bruce protocol at PM 3 to 5 were performed in 49 untreated patients with hypertension. Mean daytime (awake), and night-time (sleeping) systolic BP (SBP) and diastolic BP (DBP) values were analyzed by reviewing the patients' diaries, and the nocturnal reduction rate (NRR) of SBP and DBP were calculated according to the following formula. NRR (%) = [(daytime mean-nighttime mean)/daytime mean] x 100. The patients were divided into two groups according to the presence (dipper, n = 25) or absence (non-dipper, n = 24) of a reduction in both SBP and DBP during the night by an average of more than 10% of the daytime BP. Mean values of SBP and DBP measured over 48 hours in the dipper and non-dipper groups were similar. Responses of SBP to dynamic exercise at 2 to 5 minutes in the non-dipper group were significantly smaller than those in the dipper group (p < 0.05). Non-dipper patients with hypertension responded to dynamic exercise stress with smaller increases in SBP than did those in the dipper group. The differences in BP responses to exercise may affect the circadian blood pressure profile in dipper and non-dipper elderly patients with essential hypertension.

Exercise-induced monomorphic ventricular tachycardia from the left ventricle outflow tract

A case of exercise-induced idiopathic ventricular tachycardia (VT) arose from the left ventricular outflow tract. The QRS morphology of the VT was Rs pattern in V1 and R pattern in the lateral leads with inferior axis. The pacing at the superior interventricular septum near the mitral anulus produced the best pace mapping. Radiofrequency application to this site suppressed the VT.

Circadian blood pressure and heart rate profiles in normotensive patients with mild hyperthyroidism

We investigated the influence of thyroid hormones on the circadian blood pressure (BP) and heart rate (HR) variations in 12 normotensive subjects and 12 normotensive patients with mild hyperthyroidism. BP and HR were monitored every 30 minutes for 48 h, and electrocardiograms (ECGs) were recorded to measure the RR interval of the ECGs. We analyzed the circadian BP and HR variations, HR variability, and the morning rise in BP and HR. There was no significant difference in the average 24 h BP between groups. HR and pulse pressure were higher in the hyperthyroid group than in the control group. Though the circadian BP pattern was similar in both groups, HR decreased at night in the control group, but not in the hyperthyroid group. Spectrum analysis of the RR interval showed no increase in the high-frequency (HF) component at night in patients with hyperthyroidism. The HR did not show a morning rise in the hyperthyroid group. These findings indicate that the circadian rhythm of HR was not preserved in patients with mild hyperthyroidism. The circadian BP rhythm was similar in normotensive subjects and normotensive patients with mild hyperthyroidism, suggesting that it resulted from factors other than thyroid hormone.

Limited reproducibility of circadian variation in blood pressure dippers and nondippers

The relation between blood pressure (BP) variation and hypertensive organ damage is controversial. The reproducibility of the circadian variation pattern acceptable as the standard for discriminating between "dippers" and "nondippers" has not yet been evaluated. We evaluated the reproducibility of "dipper" and "nondipper" patterns in essential hypertensives by monitoring BP for 48 h. Noninvasive ambulatory BP and heart rate (HR) monitoring for 48 h every 30 min were performed in 253 untreated patients with mild-to-moderate essential hypertension. Mean daytime (awake) and nighttime (sleeping) systolic BP, diastolic BP, and HR values were analyzed by reviewing the patients' diaries. Patients were divided into two groups by presence (dippers) and absence (nondippers) of a reduction of both systolic and diastolic BP during the night of > 10% of the daytime pressure. A subject who was a dipper on day 1 remained a dipper on day 2 in 41% (n = 103, DD group) and changed to nondipper in 16% (n = 41, DN group). A subject who was a nondipper on day 1 remained a nondipper on day 2 in 30% (n = 75, NN group) and changed to a dipper in 13% (n = 34, ND group). Our findings indicate that there is a high risk of false-positive or false-negative results when 24-h recordings are used to identify dipper and nondipper profiles.

Dipyridamole thallium-201 single-photon emission computed tomography for prediction of perioperative cardiac events in patients with arteriosclerosis obliterans undergoing vascular surgery

The aim of the study was to determine whether or not dipyridamole thallium-201 single-photon emission computed tomography (201Tl-SPECT) has significant additive value for predicting perioperative cardiac events in patients with arteriosclerosis obliterans (ASO) undergoing vascular surgery. Routine preoperative 201Tl-SPECT was performed in 106 consecutive patients with ASO (age 68+/-8.9 years; 91 men and 15 women). The frequency of reversible defects in a clinical high-risk group (n=44) was significantly higher than in a low-risk group (n=62; 55% vs 24%, p<0.01). Perioperative cardiac events occurred in 9 patients, including 4 cardiac deaths, 1 non-fatal myocardial infarction, and 4 cases of unstable angina. Although clinical risk stratification was useful in predicting cardiac events (19% in the high-risk group vs 2% in the low-risk group, p<0.01), the positive predictive value was low. When considering a combination of 2 or more than 2 risk factors and a large reversible defect as a predictor, the positive predictive value and specificity increased from 19% to 47% and from 64% to 91%, respectively, whereas the sensitivity remained unchanged (89%). These results suggest that the addition of 201Tl-SPECT data to clinical risk-stratified patients with ASO allows better prediction of perioperative cardiac events.

Prevalence of ventricular preexcitation in Japanese schoolchildren

BACKGROUND

Wolff-Parkinson-White syndrome is thought to be a congenital disease, however, its exact prevalence is not known. This may be because of the intermittent activity of accessory pathways in some cases and fluctuations in autonomic tone.

AIMS

To investigate the prevalence of ventricular preexcitation by electrocardiography and reported symptoms in each school age child in Yamanashi prefecture.

METHODS

From 1994 to 1996, answers to a questionnaire, results of physical examination, and electrocardiography were obtained from all schoolchildren in Yamanashi prefecture (n = 92,161; total population 880,000) on admission to elementary school (age 6 to 7 years, n = 28,395), junior high school (age 12 to 13 years, n = 31,206), and high school (age 14 to 15 years, n = 32,837).

RESULTS

Elementary and junior high school students had a significantly lower prevalence of preexcitation than high school students (0.073% and 0.070% v 0.174%, p < 0.001). The prevalence of left free wall pathway was highest in high school students (n = 27) compared with elementary (n = 6) and junior high school students (n = 5) (p < 0.005). The only symptom noted in the answers to the questionnaire was palpitations. The symptomatic cases were more frequent in high school (n = 13) than in elementary (n = 1) and junior high school (n = 2) children, but not significantly. No student with preexcitation had associated heart disease or family history of Wolff-Parkinson-White syndrome or sudden death.

CONCLUSIONS

The prevalence of preexcitation in younger schoolchildren was less frequent than previously reported. The prevalence of preexcitation and left free wall pathways increased with age. The symptoms were few and there was no significant morbidity.

QT dispersion in dipper- and nondipper-type hypertension

The aim of this study was to identify the relationship of QT dispersion on 12-lead electrocardiograms and left ventricular mass index on echocardiograms associated with the circadian rhythm of blood pressure (BP). Heart rate and BP were monitored every 30 min for 48 h in 62 patients with essential hypertension using an ambulatory BP monitoring device. The patients were divided into four groups according to gender and circadian BP pattern (nocturnal BP dipper or nondipper). The patients were classified as dippers if their daytime BP decreased by at least 10% during the night and all the other subjects were classified as nondippers. Age, body mass index, and 48-h mean BP were similar among the four groups. During the night-rest period, the systolic and diastolic BP were significantly decreased in dipper-type hypertensives. The maximum QTc interval and QTc dispersion were longer in nondippers than in dippers. Left ventricular mass index (LVMI) had a tendency to increase in nondippers. The nocturnal reduction of BP significantly correlated with QTc dispersion and LVMI. The QTc dispersion significantly correlated with LVMI and interventricular septum thickness.

[Circadian variation of blood pressure and heart rate in normotensive pre- and postmenopausal women]

The aim of this study was to assess the effect of menopause on circadian profile of blood pressure (BP) and heart rate (HR) in the normotensive pre- and postmenopausal women. Systolic BP (SBP), diagnostic BP (DBP) and HR were monitored every 30 min for 48 hrs using noninvasive ambulatory BP monitoring in 24 premenopausal and 40 postmenopausal women. Mean 48-hours, daytime (awake), and nighttime (sleeping) SBP, DBP and HR values were analyzed by reviewing the patients' diaries, and the nocturnal reduction rate (NRR) of SBP, DBP and HR were calculated according to the following formula. NRR (%9 = [(daytime mean-nighttime mean)/daytime mean] x 100. The study subjects were then divided into two groups according to the presence (dipper) or absence (nondipper) of a significant reduction in nocturnal BP (> 10%). Mean SBP, DBP and HR measured over 48 hours were similar between the premenopausal and the postmenopausal group. The NRR of DBP and HR in the postmenopausal group were significantly smaller than those in the premenopausal group (17.1 +/- 6.0% vs. 13.5 +/- 7.0%, 241.1 +/- 6.0% vs. 19.8 +/- 9.0%: p < 0.05). There tended to be higher prevalence of nondipper in the postmenopausal (37%) than in the premenopausal group (29%).

Chronotherapy for coronary heart disease

Traditionally the therapy for coronary heart disease has been focused on the "how-to" problem. However, the clustering of cardiovascular events around the specific time of the day has been clarified. To solve the problems of the clustering would give us the clue to treat the coronary heart disease timely and in time. Therefore, the research has been stressed to solve "when-to" problem. The circadian variabilities in coronary heart disease has been clarified to be the function of the biologic time. Therefore, three problems were discussed in this paper. 1) The circadian variabilities in biology should be assessed based on the biologic zero hour rather than the mid-night of the mechanical clock. Our concept of the biologic zero hours has been proposed to answer this problem. 2) Daily health care with circadian order and harmony for the prevention of the coronary risk factors should be recommended as the prevention of the acute coronary risk factors as the trigger mechanism of the cardiovascular events. 3) The chronotherapy to chronic coronary risk factors such as hypertension was discussed, In hypertension the anti-hypertensive therapy should be customized individually adjusting the circadian variability of blood pressure with the proper selection of agents and time of the administration.

What time is the "biologic zero hour" of circadian variability?

Most ambulatory blood pressure monitoring (ABPM) studies have used a mechanical clock as the reference time, but there is no biologic background for assuming that midnight by the mechanical clock is zero hour by the biologic clock. The aim of this study was to determine the biologic zero hour as the zero reference time by evaluating the circadian rhythm of blood pressure, heart rate, and activity. Twenty healthy medical students (18 men, 2 women, mean age 26 years old) were recruited and blood pressure, heart rate, and physical activity were monitored simultaneously by an ABPM device every 30 min for 48 h. Four concepts of zero time were selected in this study and analyzed regarding biologic zero hour: 24:00 by the mechanical clock (clock time); the time of awakening, based on a diary (diary time); the time of a sudden increment in physical activity in the morning (activity time); and the middle of the total sleeping time, based on the diary (midsleeping time). The awakening time is a better individual index than the mechanical clock, and the midsleeping time as the zero reference point is better than the awakening time. We assessed the reproducibility of the data regarding the circadian troughs between the first and second day. The reproducibility of the day-to-day variation of the blood pressure and heart rate was poor. The reproducibility of physical activity was fairly good, but the magnitude of activity was small. A 48-h monitoring profile is superior to a 24-h monitoring period.

Administration-time-dependent effects of diltiazem on the 24-hour blood pressure profile of essential hypertension patients

The aim of this study was to identify differences in the patterns of efficacy and duration of effect by diltiazem given in different dosage forms and schedules. Blood pressure (BP) and heart rate (HR) were monitored before and after treatment by ambulatory blood pressure monitoring for 48 h every 30 min. Patients were divided for treatment assignment into 4 groups -nocturnal BP dippers and nondippers. In dipper hypertension, diltiazem-retard at 08:00 (n = 7) had the most marked antihypertensive effects during nighttime rest (SBP; 136 +/- 14/118 +/- 9 mmHg, p < 0.01 before vs. after treatment). Diltiazem-retard at 19:00 (n = 6) exerted greatest effect during daytime activity (152 +/- 7/139 +/- 6, p < 0.01) with inhibition of the morning BP rise. Diltiazem (t.i.d., n = 5) had the best effect during daytime activity (151 +/- 16/136 +/- 9, p < 0.05). However, in nondipper hypertensive patients, diltiazem (t.i.d., n = 8) had the most pronounced antihypertensive effects during nightly rest (144 +/- 12/127 +/- 12, p < 0.05). Evening medication with diltiazem retard appears to be more efficacious than the other dosage schedules.

Inhibitory effect of CV4151, a thromboxane A2 synthetase inhibitor, on ventricular arrhythmias induced by coronary artery occlusion in rats

The purpose of this study was to determine whether thromboxane A2 (TXA2) is involved in the development of ventricular arrhythmias produced by coronary artery occlusion. Ventricular arrhythmias were induced by coronary artery occlusion in 66 male Sprague-Dawley rats. Rats were separated into 4 groups, and saline (n = 19) or CV4151 (a TXA2 synthetase inhibitor)(10 mg/kg, n = 14; 30 mg/kg, n = 15; or 100 mg/kg, n = 18) was injected intravenously 5 min before coronary artery occlusion. The antiarrhythmic effect of CV4151 was assessed in terms of the number of ventricular premature complexes (VPCs), the combined duration of ventricular tachycardia (VT) and ventricular fibrillation (Vf), the incidence of Vf, and the mortality rate within 30 min after occlusion. The total number of VPCs was as follows; control: 1789 +/- 330 beats: 10 mg/kg group: 1289 +/- 302 beats: 30 mg/kg group: 1008 +/- 229 beats: 100 mg/kg group: 986 +/- 275 beats, with no significant differences between groups. The incidence of Vf was significantly reduced in the 30 mg/kg and 100 mg/kg groups, as was the combined duration of VT and Vf and the mortality rate. Our results indicate that the TXA2 synthetase inhibitor CV4151 reduces the incidence of lethal arrhythmias induced by coronary artery occlusion in rats.

Effects of bidisomide (SC-40230), a new class I antiarrhythmic agent, on ventricular arrhythmias induced by coronary artery occlusion and reperfusion in anesthetized rats; comparison with mexiletine and disopyramide

We investigated the antiarrhythmic effects of bidisomide (SC-40230), a new class I antiarrhythmic drug, in early-phase ventricular arrhythmias induced by coronary artery occlusion and reperfusion in anesthetized rats. The effects of bidisomide were compared with those of mexiletine (MXT) and disopyramide (DSP), established class I antiarrhythmic drugs. Drugs were administered intravenously, 5 min before induction of coronary occlusion. Bidisomide (5 mg/kg) reduced the number of premature ventricular complexes and the incidence of ventricular tachycardia and ventricular fibrillation similarly to MXT and DSP in rats with ventricular arrhythmias induced by coronary artery occlusion. In rats with ventricular arrhythmias induced by coronary artery reperfusion following a 5-min coronary occlusion, the antiarrhythmic effects of 5 mg/kg of bidisomide were similar to those of the same doses of MXT and DSP. All three drugs significantly slowed the heart rate. Our results suggest that bidisomide may effectively reduce the severity of life-threatening ventricular arrhythmias that occur during acute coronary syndrome.