[Left ventricular asynergy induced by positional change in a patient with ascending aortic aneurysm].
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Adult↗
Biomedical subjects
K Miyatake
Publications and source records attributed to K Miyatake.
The intron 5-inserted form of rat erythropoietin receptor is expressed as a membrane-bound form.
The cDNA encoding an intron 5-inserted form of the erythropoietin receptor (I5Epo-R) has been cloned from rat. DNA sequence analysis reveals that the insertion of intron 5, which consists of 79 bp, causes a shift in reading frame and results in termination in the region of exon 7. The deduced amino acid sequence is composed of 316 amino acid residues, which is a molecular weight of 34220. To study the function of rat I5Epo-R, we established a Chinese hamster ovary cell line expressing rat I5Epo-R. Western blot analysis and binding studies with 125I-recombinant human erythropoietin showed that the transfected cells expressed rat I5Epo-R with a molecular size of 36 kDa as a membrane-bound form, but not as a soluble form, and had a single class of binding sites with a Kd of 700 pM.
Alternative Splicing↗
Intravascular ultrasound evaluation of plaque distribution at curved coronary segments.
Although the distribution of atherosclerosis at the curved coronary segments has implications for atherogenesis and interventional procedures, few data exist regarding the plaque distribution in these sites. Therefore, we prospectively analyzed the intravascular ultrasound images of 55 coronary sites from 37 patients where the atherosclerotic plaque and pericardium were simultaneously demonstrated by intravascular ultrasound. The pericardial images were defined as a high-intensity linear echo image moving during cardiac cycles outside the vessel wall. By the line that was parallel to the pericardial image, the vessel area was divided into 2 semicircles with the same area, namely myocardial and pericardial sides. In each side, the maximal thickness, area, and percent area of plaque were measured. The plaque thickness and area of the myocardial side were significantly greater (1.5 +/- 0.5 mm, 4.9 +/- 2.1 mm or 66%, mean +/- SD) than those of the pericardial side (1.1 +/- 0.4 mm, 3.5 +/- 2.1 mm2 or 45%, p < 0.01). The maximal plaque thickness was positioned at the point with a mean angle of 139 +/- 37 degrees from the point just facing the pericardial image, indicating that atherosclerosis was eccentrically located on the opposite side of the pericardium in these coronary segments, and suggesting that the side of the pericardial image represents the outer curvature of the coronary artery. These results indicate that the pericardial images can be seen by intravascular ultrasound, facilitating the recognition of the disease distribution in situ. The eccentric plaque located on the inner wall at the curved coronary segments, probably due to uneven local shear stress, may have implications for the interventional procedures for these segments.
Aged↗
Suppressive effect of insulin on the synthesis of sucrase-isomaltase complex in small intestinal epithelial cells, and abnormal increase in the complex under diabetic conditions.
An abnormally high level of the sucrase-isomaltase (SI) complex in the small intestine of rats with streptozotocin-induced insulin-dependent diabetes mellitus (IDDM) was normalized in 11 h by the administration of insulin, in addition to normalization of the blood glucose level. Phlorizin, an inhibitor of renal glucose reabsorption, also caused normalization of the blood glucose level in the IDDM rats; however, the level of the SI complex was barely changed. When mucosa explants were cultured in a medium, the SI complex synthesized during the cultivation was accumulated as its precursor protein without maturation, owing to the absence of pancreatic proteases, and the amount of the precursor protein that accumulated in the explants was decreased by the addition of insulin into the medium. Further, the mRNA level of the SI complex in the explants incubated with insulin was obviously lower than that in the absence of insulin. These results indicate that insulin has a suppressive effect on the synthesis of the SI complex, presumably by decreasing the transcriptional level of the gene encoding the complex, in small-intestinal epithelial cells. Thus the synthesis of the SI complex might exceed normal levels in the epithelial cells as a direct result of the depletion of insulin under IDDM conditions.
Animals↗
Myocardial glucose metabolism in patients with hypertrophic cardiomyopathy: assessment by F-18-FDG PET study.
In an investigation of myocardial metabolic abnormalities in hypertrophic myocardium, the myocardial glucose metabolism was evaluated with F-18-fluorodeoxyglucose (FDG) positron emission tomography (PET) in 32 patients with hypertrophic cardiomyopathy, and the results were compared with those in 9 patients with hypertensive heart disease. F-18-FDG PET study was performed in the fasting and glucose-loading states. The myocardial regional %dose uptake was calculated quantitatively. The average regional %dose uptake in the fasting state in the patients with asymmetric septal hypertrophy and dilated-phase hypertrophic cardiomyopathy was significantly higher than that in the patients with hypertensive heart disease (0.75 +/- 0.34%, 0.65 +/- 0.25%, and 0.43 +/- 0.22%/100 g myocardium, respectively). In contrast, the average %dose uptake in the glucose-loading state in the patients with asymmetric septal hypertrophy and dilated-phase hypertrophic cardiomyopathy was not significantly different from that in patients with hypertensive heart disease (1.17 +/- 0.49%, 0.80 +/- 0.44% and 0.99 +/- 0.45%, respectively). The patients with apical hypertrophy had also low %dose uptake in the fasting state (0.38 +/- 0.21%) as in the hypertensive heart disease patients, so that the characteristics of asymmetric septal hypertrophy and dilated-phase hypertrophic cardiomyopathy are considered to be high FDG uptake throughout the myocardium in the fasting state. Patients with apical hypertrophy are considered to belong to other disease categories metabolically. F-18-FDG PET study is useful in the evaluation of the pathophysiologic diagnosis of patients with hypertrophic cardiomyopathy.
Blood Glucose↗
Serial Doppler echocardiographic evaluation of Carpentier-Edwards pericardial valve dysfunction: comparison with Ionescu-Shiley valve.
BACKGROUND: Doppler echocardiography is a valuable noninvasive method for evaluating of the occurrence and degree of either prosthetic valve stenosis or regurgitation. By using serial Doppler echocardiographic examination, we evaluated the incidence and the mode of the Carpentier-Edwards pericardial valve (CEPX) dysfunction compared with that of the Ionescu-Shiley valve (IS). METHODS AND RESULTS: After aortic and/or mitral valve replacement, 80 patients with CEPX and 111 with IS underwent Doppler echocardiography at intervals of at least 2 years after surgery. The average durations of follow-up were 6.1 +/- 2.9 years for patients with CEPX and 7.2 +/- 3.0 years for those with IS. Bioprosthetic valve stenosis was defined as reduced excursion of the bioprosthetic valve leaflets and peak gradient > or =60 mm Hg after aortic valve replacement and mean gradient > or =7 mm Hg after mitral valve replacement. Bioprosthetic valve regurgitation caused by bioprosthetic valve dysfunction was defined as grade > or =3 transvalvular regurgitation. In the aortic position, although there was no significant difference in the actuarial rate of freedom from bioprosthetic valve stenosis between patients with IS and those with CEPX (10 years after surgery, 88% +/- 7% vs 90%, NS), bioprosthetic regurgitation caused by bioprosthetic valve dysfunction occurred less frequently in patients with CEPX than in those with IS (10 years after surgery, 86% vs 54% +/- 9%, p < 0.05). In the mitral position, bioprosthetic valve stenosis occurred more frequently in patients with CEPX than in those with IS (10 years after surgery, 54% +/- 11% vs 72% +/- 8%, p < 0.01). Although grade > or =3 transvalvular bioprosthetic regurgitation occurred later in patients with CEPX than in those with IS, there was no significant difference in the actuarial rate of freedom from that regurgitation between patients with CEPX and those with IS (10 years after surgery, 63% +/- 10% vs 54% +/- 7%, NS). CONCLUSIONS: For aortic valve replacement, CEPX has good long-term durability because of the low incidence of bioprosthetic regurgitation. For mitral valve replacement, long-term durability of CEPX is poor, although medium-term durability is satisfactory.
Aortic Valve↗
Application of tissue Doppler imaging technique in evaluating early ventricular contraction associated with accessory atrioventricular pathways in Wolff-Parkinson-White syndrome.
To examine the feasibility of a tissue Doppler imaging (TDI) technique for evaluating the early contraction sites in Wolff-Parkinson-White (WPW) syndrome, we analyzed the time-sequential changes in ventricular wall motion in WPW syndrome by TDI. Fifty patients with WPW syndrome were examined by the TDI system in which the high-speed scanning technique allowed for a frame rate up to 38 frames/sec. Among 42 patients in whom the acceptable images were obtained by TDI, the early contraction, which was represented by a red or blue spot appearing on the subendocardial side at the time of the delta wave in the electrocardiogram, was demonstrated in 25 of 29 patients with left-sided accessory pathways. However, in 13 patients with right-sided pathways, the early contraction sites could be identified in only five patients. The TDI-determined early contraction sites were well coincided with the sites of the accessory pathways determined by the electrophysiologic examination (p < 0.01). After the successful radiofrequency catheter ablation, early contraction sites were found to disappear by TDI in all patients. These results demonstrate the feasibility of the TDI technique to evaluate the early ventricular contraction associated with the atrioventricular accessory pathways. We suggest that the TDI system is helpful to localize the accessory pathways and to evaluate the results after radiofrequency ablation, although further studies are necessary to demonstrate the advantage of TDI over conventional echocardiography and electrophysiologic study in the evaluation of the accessory pathways in WPW syndrome.
Adolescent↗
Comparative usefulness of myocardial velocity gradient in detecting ischemic myocardium by a dobutamine challenge.
OBJECTIVES: We tested the hypothesis that ischemic myocardium can be sensitively detected using tissue Doppler-derived myocardial velocity gradient (MVG) by a dobutamine challenge. BACKGROUND: Although tissue Doppler imaging (TDI) has recently emerged to quantify regional myocardial contraction, increased translational motion during a dobutamine challenge may affect the measurements. MVG is an indicator of regional myocardial contraction independent of the translational motion. METHODS: We studied 19 patients with (n = 13) and without (n = 6) confirmed single-vessel coronary artery disease. Left ventricular short-axis tissue Doppler images were obtained along with conventional echocardiograms during a submaximal two-step dobutamine challenge (10 and 30 microg/kg body weight per min). Endocardial velocity as well as MVG were derived from TDI using computer analysis in the anteroseptal and posterior segments and were compared with visual interpretation. RESULTS: MVG demonstrated a significant dose-responsive increase in the nonischemic segments (anteroseptal: 2.6 +/- 0.8/s to 6.0 +/- 1.0/s [mean +/- SD], p < 0.05; posterior: 3.9 +/- 0.7/s to 7.6 +/- 1.8/s, p < 0.05) but remained unchanged in the ischemic segments (anteroseptal: 2.5 +/- 0.8/s to 2.7 +/- 0.7/s, p = NS; posterior: 3.4 +/- 1.0/s to 4.1 +/- 0.9/s, p = NS). Endocardial velocity failed to clearly demonstrate the differing responses between the nonischemic (anteroseptal: -2.3 +/- 1.2 to -2.7 +/- 1.6 cm/s, p = NS; posterior: 3.8 +/- 1.1 to 73 +/- 2.7 cm/s, p < 0.05) and ischemic segments (anteroseptal: -2.1 +/- 0.5 to -2.8 +/- 0.8 cm/s, p = NS; posterior: 4.2 +/- 0.8 to 6.5 +/- 2.6 cm/s, p = NS). Wall motion abnormality was hardly detectable with visual interpretation (wall motion score range 1.00 to 1.33). CONCLUSIONS: Abnormal segments could be sensitively detected by using MVG in a submaximal dobutamine challenge, even where conventional methods failed to detect the abnormality.
Aged↗
Comparative efficacy of the maze procedure for restoration of atrial contraction in patients with and without giant left atrium associated with mitral valve disease.
OBJECTIVES: We sought to determine the effectiveness of the maze procedure for restoring atrial contraction in patients with and without giant left atrium (GLA). BACKGROUND: Although the maze procedure has been reported to be effective for refractory atrial fibrillation, it is unknown whether this procedure can restore effective atrial contraction in patients with GLA. METHODS: Nineteen patients with and 32 patients without GLA were studied with Doppler echocardiography before and after the maze procedure. Peak velocity and the time-velocity integral of the left ventricular diastolic filling wave during atrial contraction (A wave) and the atrial filling fraction calculated as the ratio of the time-velocity integral of the A wave to that of total diastolic filling were compared between patients with and without GLA. A peak A wave velocity > or =10 cm/s was considered to indicate echocardiographic evidence of effective atrial contraction. RESULTS: Regular rhythm with P waves was restored in 10 patients (53%) with and 26 (81%, p < 0.05) without GLA. Four patients (21%) with and 21 patients (66%, p < 0.01) without GLA showed effective atrial contraction by echocardiography. Once atrial contraction was resumed, the degree of atrial contraction was comparable between patients with and without GLA (17+/-5% vs. 17+/-4% for atrial filling fraction at 12 months, respectively). CONCLUSIONS: Although most patients without GLA had restored atrial contraction by the maze procedure, it was resumed in fewer patients with GLA. However, once atrial contraction was resumed, the degree of atrial contraction was comparable between patients with and without GLA. Therefore, the maze procedure may be an option in selected patients with GLA.
Aged↗
Noninvasive differential diagnosis between chronic pulmonary thromboembolism and primary pulmonary hypertension by means of Doppler ultrasound measurement.
OBJECTIVES: The purpose of this investigation was to differentiate chronic pulmonary thromboembolism (CPTE) from primary pulmonary hypertension (PPH) by using noninvasive Doppler ultrasound techniques. BACKGROUND: A recent investigation in our laboratory has indicated that the pulmonary artery (PA) pressure waveform conveys significant information that can be used to differentiate CPTE from PPH. Pulse pressure was markedly larger in CPTE than in PPH, indicating that the major occlusive site is central in CPTE and peripheral in PPH. METHODS: In 19 patients with CPTE and 16 patients with PPH, we estimated PA systolic pressure and diastolic pressure from the velocities of tricuspid regurgitation and pulmonary regurgitation, respectively. RESULTS: Estimated systolic pressure was not significantly different between CPTE and PPH (mean [+/-SD] 81+/-20 and 79+/-21 mm Hg, respectively, p=NS). Pulse pressure normalized by systolic pressure was higher in CPTE than in PPH (0.82+/-0.05 vs. 0.63+/-0.10, respectively, p < 0.01). Pulse pressure normalized by mean pressure was also higher in CPTE than in PPH (1.65+/-0.30 vs. 0.94+/-0.25, respectively, p < 0.01). Receiver operating characteristic analysis indicated that pulse pressure normalized by systolic pressure separated CPTE from PPH, with a sensitivity of 0.95 and a specificity of 1.00. Pulse pressure normalized by mean pressure also separated them, with a sensitivity of 0.95 and a specificity of 1.00. CONCLUSIONS: Normalized pulse pressures estimated from Doppler ultrasound measurements enable us to noninvasively differentiate between CPTE and PPH.
Adult↗
Peak negative myocardial velocity gradient in early diastole as a noninvasive indicator of left ventricular diastolic function: comparison with transmitral flow velocity indices.
OBJECTIVES: We sought to assess the clinical significance of peak negative myocardial velocity gradient (MVG) in early diastole as a noninvasive indicator of left ventricular (LV) diastolic function. BACKGROUND: Peak systolic MVG has been shown useful for the quantitative assessment of regional wall motion abnormalities, but limited data exist regarding the diastolic MVG as an indicator of LV diastolic function. METHODS: Peak negative MVG was obtained from M-mode tissue Doppler imaging (TDI) in 43 subjects with or without impairment of systolic and diastolic performance: 12 normal subjects, 12 patients with hypertensive heart disease (HHD) with normal systolic performance and 19 patients with dilated cardiomyopathy (DCM), and was compared with standard Doppler transmitral flow velocity indices. In a subgroup of 30 patients, effects of preload increase on these indices were assessed by performing passive leg lifting. In an additional 11 patients with congestive heart failure at the initial examination, the measurements were repeated after 26+/-16 days of volume-reducing therapy. RESULTS: Peak negative MVG was significantly depressed both in HHD (-3.9+/-1.3/s, p < 0.01 vs. normal=-7.7+/-1.5/s) and DCM (-4.4+/-1.4/s, p < 0.01 vs. normal). In contrast, transmitral flow indices failed to distinguish DCM from normal due to the pseudonormalization. Transmitral flow velocity indices were significantly altered (peak early/late diastolic filling velocity [E/A]=1.1+/-0.5 to 1.5+/-0.7, p < 0.01; E deceleration time=181+/-41 to 153+/-38 ms, p < 0.01), while peak negative MVG remained unchanged (-5.3+/-2.2 to -5.3+/-2.0/s, NS) by leg lifting. Volume-reducing therapy resulted in the apparent worsening of the transmitral flow velocity pattern toward abnormal relaxation, as opposed to peak negative MVG, which improved by the therapy (p < 0.05). CONCLUSIONS: Peak negative MVG derived from TDI may be a noninvasive indicator of LV diastolic function that is less affected by preload alterations than the transmitral flow velocity indices, and thereby could be used for the follow-up of patients with nonischemic LV dysfunction presenting congestive heart failure.
Adult↗
Impact of presence of abnormal wall motion on echocardiographic determination of left ventricular function with automated boundary detection technique: re-evaluation.
It is still unclear whether echocardiography with an automated boundary detection technique (ABD) can accurately determine the left ventricular (LV) volume and function particularly in the presence of LV wall asynergy. We intended to re-evaluate the reliability and application of the ABD, which was based on the acoustic quantification technique (Sonos 2500, Hewlett Packard) for the LV volume measurement in patients without or with LV wall asynergy. A total of 80 patients (mean age 56 years) who underwent left ventriculography (LVG) were divided into two groups. The group A consisted of 29 patients with normal LV wall motion and the group B consisted of 51 patients with generalized or regional LV wall motion abnormality. In group A patients, the LV end-diastolic volume (LVEDV) was 96 +/- 25 ml by ABD and 112 +/- 33 ml by LVG and those of LV end-systolic volume (LVESV) were 44 +/- 14 ml by ABD and 48 +/- 17 ml by LVG, thus resulting in the underestimation of LV volume by 12% in average. Under these conditions, the LV ejection fraction (LVEF) by ABD, 54 +/- 8%, correlated well with that by LVG, 58 +/- 7%. Although underestimation of LV volume by 17% in average also occurred in groups B (N.S.), LVEF was found to correlate well with that by LVG; 27 +/- 8% vs 30 +/- 11% (r = 0.87, SEE = 3.1%) for 21 patients with the generalized LV asynergy; 39 +/- 10% vs 39 +/- 12% (r = 0.86. SEE = 3.3%) for 30 patients with the regional LV asynergy. These results demonstrate the feasibility of the ABD in determining the LVEF, although underestimation can occur in measuring the absolute LV volume in patients with or without LV asynergy.
Case-Control Studies↗
Hemodynamic effect of amrinone depends on pretreatment vascular resistance in patients with evolving congestive heart failure: correlation between vascular resistance and neurohormonal activity.
We investigated the hemodynamic effects of amrinone and assessed its effects on neurohormonal factors in 15 patients with evolving congestive heart failure with various origins. We serially determined the pulmonary and systemic vascular-resistance indices after amrinone infusion and examined the relation between changes in hemodynamic parameters and changes in concentrations of norepinephrine, atrial natriuretic peptide, angiotensin II, and endothelin-1 in the pulmonary capillary wedge region (PCWR) and in the peripheral veins. Amrinone significantly reduced pulmonary vascular-resistance index (PVRI; Wood x m2) in patients with high PVRI (> or =15) before the infusion, significantly reduced systemic vascular-resistance index (SVRI; Wood x m2) in patients with high SVRI (> or =50) before the infusion, and had little effect on vascular resistances in patients with low PVRI (<15) and low SVRI (<50). The reduction in PVRI was correlated with the reduction in the endothelin-1 level (r = 0.75) in the PCWR, and the reduction in SVRI with norepinephrine level (r = 0.70) in the peripheral veins. The angiotensin II level did not change throughout the study. These findings suggest that amrinone had selective hemodynamic effects on pulmonary and systemic circulations with neurohormonal effects, according to PVRI and SVRI before infusion.
Aged↗
Preload and incident angle independent index of left ventricular contractility determined by continuous wave Doppler echocardiography.
Although left ventricular dP/dtmax can be accurately assessed using Doppler echocardiography, the fact that Doppler-derived dP/dtmax depends both on preload and Doppler incident angle limits its clinical value. We investigated the clinical usefulness of Doppler-derived (dP/dtmax)/IP (IP, isovolumic pressure), which is known to be relatively insensitive to preload and theoretically independent of the incident angle in 9 subjects. We conclude that Doppler-derived (dP/dtmax)/IP is relatively insensitive to both the incident angle and preload. In addition to its noninvasiveness, these unique features makes it very attractive as a clinical index of ventricular contractility.
Echocardiography, Doppler↗
Comparison of automatic boundary detection and manual tracing technique in echocardiographic determination of left atrial volume.
Previous reports have indicated that echocardiography with automatic boundary detection (ABD) is useful for the noninvasive estimation of left ventricular volume. However, few data exist regarding the measurement of left atrial (LA) volume, which also provides pivotal information in the clinical setting. Therefore, the feasibility of LA volume measurement by ABD in comparison with the manual tracing using modified Simpson's method (SM) was evaluated. Fifty-nine patients with coronary artery-disease with sinus rhythm were examined. Using ABD, a region of interest was set around the LA border and mitral annulus from an apical four-chamber view. The maximal and minimal LA volume (Vmax and Vmin) were measured from the volume waveform. Using the SM, the maximal and minimal LA volume were measured by the manual tracing on frozen frames at the apical four-chamber view. The ABD displayed a curve of LA volume change that consisted of passive emptying, diastasis, and active emptying phases during the left ventricular diastolic period. Under these conditions, the Vmax and Vmin were 43.7 +/- 11.2 ml and 21.1 +/- 7.6 ml, respectively, yielding the volume change of 22.6 +/- 6.0 ml. By the SM, Vmax and Vmin were 43.1 +/- 9.9 ml (r = 0.94, p < 0.0001, y(ABD) = 0.91x (SM) + 3.6) and 22.0 +/- 9.0 ml (r = 0.91, p < 0.0001, y = 0.94x + 0.7), respectively, and the volume change was 22.8 +/- 6.1 ml (r = 0.82, p < 0.0001, y = 0.84x + 3.8). These results indicate that the ABD from the apical four-chamber approach could provide an accurate estimation of LA volume change, suggesting the potential value of this method in assessing LA function, although some technical difficulties need to be further overcome.
Adult↗
Suppression by water extracts of Sophora plants of sucrose-induced hyperglycemia in rats and inhibition of intestinal disaccharidases in vitro.
Partially purified hot-water extracts of the roots of plants of the Sophora family suppressed the increase in blood glucose concentration of rats in the oral sugar tolerance test. The extracts also inhibited rat intestinal sucrase and maltase. The most potent sample was about 15 times more active than catechin, a positive control, in these experiments.
Animals↗
Alpha 2-adrenoceptor-mediated antisecretory effect of hypoxia in conscious rats.
Gastric acid secretion is suppressed, resulting in a significant rise in gastric pH, when conscious rats are exposed to hypoxia (Yamaji et al., 1996). When adrenal medullectomized rats were exposed to moderate (10.5% O2) hypoxia for 3 h, gastric acid secretion was restored to nearly the level in normoxia by the adrenal medullectomy. In severe (7.6% O2) hypoxia, the operation also caused an increase in the level of gastric acid output, although the extent was lower than that under 10.5% O2 hypoxic conditions. Gastric pH was normalized by the operation even with 7.6% O2 hypoxia. Similar results were obtained when reserpine, which causes an adrenergic discharge, was administered. When an alpha 2-adrenoceptor blocking agent, yohimbine, was administered, the inhibitory effect of 10.5% and 7.6% O2 hypoxia on gastric acid secretion was almost completely removed. However, neither prazosin (an alpha 1-adrenoceptor blocker) nor propranolol (a beta-adrenoceptor blocker) showed any significant effects on gastric acid output in hypoxia. These results indicate that acute hypoxia stimulated the adrenergic response from the adrenal medulla, and that gastric acid secretion was consequently suppressed through alpha 2-adrenoceptor.
Adrenal Medulla↗
Low sucrase activity in the small intestine of a senescence-accelerated strain of mouse, SAMP1.
The small intestinal sucrase activity in a senescence-accelerated strain of mouse, SAMP1, was significantly lower than that in other strains, including its control strain, SAMR1. In contrast, the activity of isomaltase, which usually associates with sucrase to form a complex enzyme (SI complex), in SAMP1 was comparable to that in other strains. Thus, the ratio of the sucrase to isomaltase activities (S/I ratio) in SAMP1 was very low (about 0.15), compared with that in other strains (around 0.7). The S/I ratio in SAMP1 was abnormally low, even at a young age, indicating that senescence did not result in the low sucrase activity. Western blot analysis suggests that a large part of the isomaltase subunit occurred alone without the association of the sucrase subunit in this strain. In contrast, Northern blot analysis shows that the level of mRNA for the SI complex in SAMP1 was comparable to that in SAMR1. When the pancreatico-biliary ducts were ligated in SAMP1 to reduce the level of pancreatic proteases, a remarkable increase was observed in the sucrase activity, whereas the isomaltase activity was increased to a much smaller extent. This marked increase in sucrase activity resulted in the S/I ratio increasing to 0.84 18 h after the ligation. These results suggest the sucrase subunit of the SI complex to be abnormally unstable against pancreatic proteases in SAMP1.
Aging↗