Thrombolytic therapy for acute myocardial infarction-effects, problems and strategies

The effects and problems of coronary thrombolysis (CT) were investigated in 652 patients with initial acute myocardial infraction (AMI). Nosocomial mortality obtained by matching factors which determined prognosis was significantly lower in patients treated by CT (8.3%) than in those who did not undergo CT (18.1%). Regardless of whether the treatment was intracoronary arterial (ICT) or intravenous (IVCT), the primary cause of the decreased mortality was reperfusion of the coronary artery responsible for infarction (mortality 6.1% in the reperfused group vs 21.5% in the ineffective group). CT therapy improved left ventricular ejection fraction (LVEF), the nosocomial mortality rate, and regional wall motion at the site of infarction in cases that were reperfused less than 3 h, 3-6 h, and even 6 or more hours after the therapy. The long-term prognosis was significantly better in the reperfused group than in the ineffective group for 5 years and 7 months after therapy. However, CT was accompanied by both (1) poor prognosis in the ineffective group; and (2) unfavorable effects on the prognosis and on the daily life of patients with severe stenosis even after treatment. Accordingly, supplemental ICT and rescue PTCA (strategy (A)) were performed to treat the first problem, and deferred PTCA (strategy (B)) was conducted to treat the second problem in 80 patients with initial AMI. As a result, strategy (A) increased the coronary reperfusion rate to 94.3%, and strategies (A) and (B) together decreased the nosocomial mortality rate of 8.5% to 3.8%, and reduced the risk of death by 55.3%.

The efficacy of monatepil, a new calcium antagonist, in the treatment of essential hypertension

A multicenter, open-label trial in Japan examined the efficacy, safety, and optimal dose of monatepil (AJ-2615) as monotherapy and in combination therapy with angiotensin-converting enzyme (ACE) inhibitors or beta-blockers. Patients with essential hypertension who had never been treated or had been refractory to conventional antihypertensive agents were enrolled in the trial. During a 4-week control period patients assigned to monotherapy received placebo and those assigned to combination therapy received an ACE inhibitor or beta-blocker and placebo. Patients with systolic blood pressure (BP) > or = 160 mm Hg and diastolic BP > or = 95 mm Hg at the end of the control period were enrolled in the study. The initial dose of monatepil was 30 mg/day in monotherapy and 15 mg/day in combination therapy; the daily dose was titrated to 60 mg/day according to the antihypertensive response. The treatment period was 8 to 12 weeks. Blood pressure decreased from 168 +/- 8/100 +/- 6 to 142 +/- 9/85 +/- 7 mm Hg (SD) with monatepil monotherapy, from 171 +/- 11/102 +/- 6 to 141 +/- 9/84 +/- 6 mm Hg in combination with ACE inhibitors, and from 175 +/- 13/102 +/- 7 to 153 +/- 21/91 +/- 9 mm Hg in combination with beta-blockers (P < .001). When patients in whom mean BP decreased by > or = 13 mm Hg were defined as responders, the response rate was 80.4%, 78.1%, and 51.6% in the respective groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of manual and computer-assisted automatic measurements of wall thickness of the left ventricle in two-dimensional echocardiography

To investigate the clinical applicability of automatic analysis of wall thickness in two-dimensional echocardiography, computer-assisted and conventional manual methods were compared in 26 cases. An echo threshold was automatically set in short-axis echo images through a discriminatory variance analysis of the signal-to-noise ratio. A fixed standard was determined inside the left ventricle using the circle window method, which we developed previously. Two abrupt echo reflections were selected as candidate points for the borders, and an outward search was conducted in all directions from a fixed standard to separately delineate the endocardial and epicardial interfaces. Interpolation using a spline function was applied to these points to complete the border lines. Differentiation was also used to eliminate the anterior and posterior papillary muscles. Significant correlations of r = 0.98 were found between the computer and manual assessments of the epicardial and endocardial intraluminal ventricular areas (p < 0.01). A correlation of r = 0.87 was also obtained for myocardial wall thickness as determined by the 2 methods (p < 0.01). Variability of the reproducibility using the computer method was 0.22% for the epicardial area and 0.64% for the endocardial area. These results confirm that computer-aided automatic measurement of wall thickness is clinically applicable to two-dimensional echocardiography.

Rat renin promoter activity in cultured cells and transgenic mice

Renin, a key enzyme controlling blood pressure, is mainly synthesized in kidney. To characterize the rat renin promoter, we have constructed a reporter gene containing the 238-bp putative regulatory region linked to a bacterial chloramphenicol acetyltransferase (CAT), and analyzed its promoter activity by in vitro transfection and introduction of the CAT fusion gene into germline of mice. CAT activity was detected in transfected embryonic kidney-derived 293 cells, but not in HeLa cells derived from cervical carcinoma, showing that the putative promoter region of the rat renin gene directs transcription in a cell type-dependent manner. To examine whether the sequence was sufficient to regulate the expression of the CAT chimeric gene in mice, we generated seven transgenic mice carrying the reporter construct. Unexpectedly, the transgene was not expressed in any of the independent transgenic mice examined. These results suggest one possibility that an additional control region may be required for efficient expression of the rat renin promoter in developing mice.

Production of transgenic rats using pregnant and pseudopregnant rats prepared at a breeding farm

We used pregnant and pseudopregnant Wistar-Imamichi rats, prepared at a breeding farm, for production of transgenic rats. The donor and recipient rats were transported to our facility for ova manipulation and embryo implantation, respectively. As a foreign gene, 1.9 kb of a hybrid gene was constructed with the rat renin promoter and chloramphenicol acetyltransferase-coding gene. Fertilized oocytes were collected from the donor and the foreign DNA was microinjected into the pronuclei of 539 oocytes by the method of Hochi. The manipulated oocytes were cultured to the 2-cell stage. One hundred seventeen 2-cell embryos were implanted in the recipient rats. Of 67 newborns, 55 rats grew up to be 3-week-old weanlings. Genomic DNA was extracted from the tail of these weanlings and examined by polymerase chain reaction analysis. Six transgenic rats were found to have been generated by the present method. In this way, transgenic rats were produced by an efficient combination of breeding farm utilization and laboratory research.

Neurotropism of mouse-adapted haemagglutinating encephalomyelitis virus

The propagation of a mouse-adapted strain (67N) of haemagglutinating encephalomyelitis virus in infected mice and murine cells was examined by viral re-isolation and immunostaining. Viral propagation was strictly limited to the neurons and to an established line of neuroblastoma cells in in-vivo and in-vitro experiments. These results provide adequate evidence that this virus is neurotropic.

Chimeric renin-angiotensin system demonstrates sustained increase in blood pressure of transgenic mice carrying both human renin and human angiotensinogen genes

A reaction between enzyme renin and its only natural substrate angiotensinogen is the initial and rate-limiting step for producing a potent vasoconstrictor angiotensin II as the final product of the renin-angiotensin system, a contributory factor in the pathogenesis of hypertension. In order to assess the role of the interaction of human renin with human angiotensinogen in the development of high blood pressure, we have constructed the chimeric renin-angiotensin cascade in mice comprising both human renin and human angiotensinogen as well as the endogenous angiotensin-converting enzyme and angiotensin II receptor by cross-mating separate lines of transgenic mice carrying either the human renin or human angiotensinogen genes. Although each single gene carrier did not develop hypertension despite the observed normal tissue-specific expression of the transgenes, dual gene strains exhibited a chronically sustained increase in blood pressure. Administration of a human renin-specific inhibitor (ES-8891) was effective in reducing the elevated blood pressure only against the cross-mated hybrid mice, but treatment of an angiotensin-converting enzyme inhibitor (captopril) and a selective antagonist (DuP 753) directed at the angiotensin II receptor decreased the basal level of blood pressure even in single gene carriers as well as in dual gene mice. These results clearly demonstrated that the sustained increase in blood pressure of the hybrid mice was initiated by the interaction between the products of the two human genes.

Differential modulation of mitogenic and metabolic actions of insulin-like growth factor I in rat glomerular mesangial cells in high glucose culture

In order to explore the possible contribution of insulin-like growth factor I to the development of diabetic nephropathy, the effect of glucose on the mitogenic and metabolic actions of insulin-like growth factor I in cultured rat glomerular mesangial cells was examined. The stimulation of [3H]-thymidine incorporation by insulin-like growth factor I in the cells exposed to high concentrations (55 mmol/l) of glucose (4.6 +/- 1.3 fold stimulation) was significantly suppressed as compared with that in the cells cultured in 11 mmol/l glucose (17.5 +/- 0.8 fold). In contrast, [3H]-amino-isobutylic acid uptake into the mesangial cells was significantly enhanced by glucose (2.03 +/- 0.03 nmol.mg protein-1. 15 min-1 at 55 mmol/l glucose vs 0.59 +/- 0.01 at 11 mmol/l glucose), while 2-deoxyglucose uptake remained unchanged. [125I]-insulin-like growth factor I binding was slightly but significantly increased in the cells exposed to high concentrations of glucose. Thus, glucose may modulate the mitogenic and metabolic actions of insulin-like growth factor I differently in cultured mesangial cells probably at the post-insulin-like growth factor I receptor level. These results may indicate that the differential modulation of the actions of insulin-like growth factor I by glucose could result in the increase in amino acid uptake and decrease in the cell proliferation in the mesangial cells, possibly leading to enhanced mesangial matrix synthesis with a relatively small increase in mesangial cell volume as seen in diabetic nephropathy.

[Quantitative cytochemical analysis of T1 breast cancer]

The authors attempted to estimate the relationship between three biological parameters (nuclear DNA content, PCNA (proliferating cell nuclear antigen)/cyclin, HER-2/neu oncoprotein) and lymph node metastasis. We evaluated 37 breast cancers which were less than 2 cm in maximum dimension. Quantitative analysis was performed using a CAS 200 Image Analysis System, after Feulgen staining and immunochemical staining using anti-PCNA/cyclin monoclonal antibody and anti-HER-2/neu oncoprotein polyclonal antibody. In lymph node-negative cases 20.0% were aneuploid, while in lymph node-positive cases 58.8% were aneuploid. A total of 20.0% lymph node-negative cases were in the high proliferation group, as opposed to 52.9% of lymph node-positive cases. This analysis revealed a significant relationship between cell proliferation and lymph node metastasis. Analysis of the expression of HER-2/neu oncoprotein revealed no significant relationship between overexpression of HER-2/neu oncoprotein and lymph node metastasis, but the expression of HER-2/neu oncoprotein was significantly related to a shorter relapse-free survival.

Nipradilol inhibits rat mesangial cell mitogenesis through the activation of soluble guanylate cyclase

Nipradilol is a beta-adrenoreceptor blocking agent, whose structure contains an NO2 group. Thus, it is possible that it modulates the function of glomerular mesangial cells through the activation of soluble guanylate cyclase. To prove this hypothesis, we examined the effect of nipradilol on soluble guanylate cyclase, intracellular cyclic guanosine monophosphate (cGMP) accumulation, and the mitogenesis of cultured rat glomerular mesangial cells. Nipradilol increased intracellular cGMP accumulation in a dose-dependent manner through the activation of soluble guanylate cyclase. Furthermore, nipradilol inhibited the incorporation of [3H]thymidine into the mesangial cells stimulated by 2.5% fetal bovine serum in a dose-dependent manner. These results indicate that nipradilol may modulate mesangial cell function through an increase in intracellular cGMP resulting from the activation of soluble guanylate cyclase.

[Effect of glucose on soluble guanylate cyclase in cultured rat mesangial cells]

The intracellular content of cyclic GMP (cGMP) is known to mediate the effects of various vasodilating substances on glomerular mesangial cells. However, little is known about the role of soluble guanylate cyclase (SGC) in these cells in diabetes. We, therefore, investigated the changes in SGC activity as well as the cGMP content in rat mesangial cells (MC) cultured under high glucose or hypertonic conditions. The following results were obtained. 1. Sodium nitroprusside (SNP) (10(-4) M, 10min.) increased cyclic GMP (cGMP) content in MC from 8.17 +/- 0.99 pmol/mg protein to 981.6 +/- 86.3. 2. SNP (10(-4) M) stimulated SGC activity from 38.3 +/- 10.8 pmol cGMP formed/mg protein/10 minutes to 74.4 +/- 5.2. 3. In the coincubation experiment with bovine aortic endothelial cells, bradykinin (10(-6) M, 10min.) increased cGMP content in MC from 6.24 +/- 1.35 to 348.3 +/- 45.3. However, 4. the activity of SGC and SNP-induced increase of cGMP were not influenced by culturing MC in high glucose or hypertonic media. Similarly, the cGMP increase in MC coincubated with BAEC under bradykinin stimulation was not altered by culturing under high glucose or hypertonic conditions. These data suggested that SGC may play an important role in the regulation of cGMP content in MC. However, this enzyme may not be involved in the increase of cGMP content in MC cultured under high glucose condition.

Dependence of angiotensin production in transgenic mice carrying either the human renin or human angiotensinogen genes on species-specific kinetics of the renin-angiotensin system

In order to study the functional role of the renin-angiotensin system in the control of blood pressure, projects were initiated using transgenic mice carrying either the human renin gene or the human angiotensinogen gene. To extend the usefulness of the transgenic model system of hypertension research, a two-tiered strategy for generation of transgenic mice with high blood pressure has been developed. This unique system allows the establishment of transgenic lines with a strict species specificity of the renin-angiotensinogen reaction exhibited by transgene products that are regulated in a tissue specific manner. In this report, the strategy concerning the "two-tiered method" is presented and evidence is provided the overproduction of angiotensin occurs only in the combined reaction with human renin and human angiotensinogen expressed in transgenic mice.

Species-specific kinetics of mouse renin contribute to maintenance of normal blood pressure in transgenic mice with overexpressed human angiotensinogen

Angiotensinogen, the precursor of a vasoactive octapeptide angiotensin II, is the only known natural substrate of renin, and its reaction exhibits strict species specificity and is the rate-limiting step in the renin-angiotensin system that controls the blood pressure. We measured blood pressure and heart rate of the transgenic mice with overproduced human angiotensinogen, and showed no significant difference in these parameters between transgenic and nontransgenic mice. We also provided evidence that mouse renin could not cleave human angiotensinogen, indicating a lack of angiotensin production from the human substrate. These results suggested that the blood pressure of transgenic mice is normally maintained, probably due to the inability of mouse renin to release angiotensin from the transgene products.

Hypertension and the development of complications in patients with non-insulin dependent diabetes mellitus in Japan

Hypertension is a very frequent condition in individuals with non-insulin dependent diabetes mellitus (NIDDM) in Japan and has affected the occurrence of late diabetic complications, especially stroke and nephropathy. Despite similar characteristics of hypertension among Japanese and white patients, the effect of hypertension on the development of coronary artery disease (CAD) in these two populations is strikingly different. In white NIDDM patients, hypertension is one of the major risk factors for the development of CAD. However, CAD is an infrequent complication in NIDDM patients in Japan, even though they have hypertension, lipid abnormalities, and renal complications.

Identification and characterization of aldose reductase in cultured rat mesangial cells

Although the enhanced activity of the polyol pathway has been detected in diabetic glomeruli, the intraglomerular localization of this pathway has not yet been well defined. In this study, we attempted to identify aldose reductase, a key enzyme of the polyol pathway, in cultured rat mesangial cells and to characterize the properties of this enzyme using enzymological and immunological methods. When the aldose reductase (DL-glyceraldehyde-reducing) activity was analyzed in mesangial cell extract, the Lineweaver-Burk plot showed concave downward curvature, and the Michaelis constant was 0.83 mM DL-glyceraldehyde, and this activity was noncompetitively inhibited by an aldose reductase inhibitor, ICI-128,436. The enzyme activity was enhanced by the addition of sulfate ion and partially suppressed by barbital. The enzyme cross-reacted with the antisera against rat lens and testis aldose reductases on Ouchterlony plate, and migrated to the region of molecular weight of about 36,500 Da on Western blotting. The presence of aldose reductase mRNA was also confirmed by Northern analysis using cDNA for rat aldose reductase, 10Q. From these results, it was concluded that the aldose reductase may exist in rat glomerular mesangial cells and may play a role in the development of diabetic glomerulopathy, though the coexistence of aldehyde reductase(s) may not be fully ruled out.

High blood pressure is a risk factor for the development of microalbuminuria in Japanese subjects with non-insulin-dependent diabetes mellitus

In this study, 52 nonproteinuric Japanese patients with non-insulin-dependent diabetes (NIDDM) were followed from 1985 to 1990 to investigate the rate of development and progression of microalbuminuria and the factors which influence it. In 1985, 34 patients were normoalbuminuric, and 18 patients were microalbuminuric. Five years later, 11 of 34 initially normoalbuminuric patients (32.4%) developed microalbuminuria, and 6 of 18 initially microalbuminuric patients (33.3%) developed overt proteinuria. At the beginning of the study, hypertension existed more frequently in the patients who later developed microalbuminuria (8 of 11, 72.7%) than in the patients who stayed normoalbuminuric (4 of 23, 17.4%). Age-adjusted values of mean blood pressure (+/- SEM) at the beginning of the study in the patients who developed microalbuminuria (98.2 +/- 3.4 mm Hg, n = 11) were significantly higher than those in the patients who stayed normoalbuminuric (87.3 +/- 2.4 mm Hg, n = 23). In six patients who developed overt proteinuria, initial urinary albumin excretion rates (AER) were higher than those in the patients who stayed microalbuminuric, and four patients who presented with initial AER greater than 100 micrograms/min all developed overt proteinuria. These results indicate that, in Japanese patients with NIDDM, the rate of development of microalbuminuria is faster than that reported in Caucasian IDDM, and preexisting hypertension with relatively poor control of blood pressure may be a risk factor for the development of microalbuminuria.

[Role of superoxide anion on onset and maintenance of hypertension in spontaneously hypertensive rats]

Endothelium-derived relaxing factor (EDRF) is a substance that is released by the vascular endothelium and mediates vasodilator responses induced by various substances including acetylcholine (AC). Superoxide anion (O2-) inactivates EDRF. It is well known that the endothelium-dependent vascular relaxations to AC are depressed in the aorta of spontaneously hypertensive rats (SHR). We studied the role of O2- on onset and maintenance of hypertension in SHR. Male 4- and 17-week old SHR (4SHR, 17SHR), and enalapril treated 17-week old SHR (5 mg/kg/day for 4 weeks: ETSHR), and age-matched normotensive Wistar-Kyoto rats (WKY; 4WKY, 17WKY) were used. Relaxation responses to AC or superoxide dismutase (SOD) were measured in isolated aortae from rats. Mean arterial pressure (MAP) was measured after injection of SOD in rats under conscious state. Systolic blood pressure of 4SHR, 17SHR, ETSHR, 4WKY, and 17WKY were 129 +/- 2 mmHg, 203 +/- 3 mmHg, 158 +/- 3 mmHg, 97 +/- 1 mmHg, and 138 +/- 2 mmHg, respectively. Although relaxation responses to AC were decreased in aortae from 4SHR, 17SHR, and ETSHR compared with those from age-matched WKY, relaxation responses to SOD dit not differ between SHR and corresponding WKY. Whereas the injection of SOD(10000 U/kg) elicited a significant reduction of MAP in 4SHR (-11 +/- 3 mmHg) and 17SHR (-24 +/- 5 mmHg), it has no effect in WKY. These data suggest that AC mediated endothelium-dependent relaxation is attenuated in SHR and that excessive O2- in the endothelium resulted from hypertension may contributes the decreased response in SHR.

Development of mouse oocytes superovulated at different ages

The development of oocytes superovulated at 25, 50, or 90 days in four mouse strains (C57BL/6N, DBA/2N, ICR, and B6D2F1) was examined using the techniques of in vitro fertilization, culture, and transfer of two-cell embryos to pseudopregnant recipients. The highest number of ova were obtained from superovulated 25-day-old mice in all strains. Approximately 80% of oocytes developed to the two-cell stage after in vitro fertilization. Of these living oocytes, 60% developed to weanling stage through the recipient. These results suggested that donor age among 25, 50, or 90-day-old mice has no influence on the viability of superovulated oocytes. Consequently, we conclude that superovulated 25-day-old mice offer an economical and efficient source of viable oocytes for the production of transgenic mice.