[Development of an experimental rat model of intraabdominal abscess by Escherichia coli alone. II. Interactions between an intraabdominal abscess and a host]

It has been demonstrated that an intraabdominal abscess by Escherichia coli alone can be developed without fail although anaerobes or barium sulfate are not used. We investigated the properties and the influence of this abscess on the host. We took the method of bacterial implantation by insertion of a double gelatin capsules containing Escherichia coli suspension of which concentration was adjusted to five grades into the peritoneal cavity of Wister rats. Abscesses were developed in the survived rats on which live bacteria had been inoculated. Only Escherichia coli were found in these abscesses by culture whereas no death was occurred and no abscess was developed in the rats on which no bacterium or heat-killed ones had been inoculated. As for non-survivors at the 7th postoperative day, all of them died of panperitonitis and no abscess was developed. An abscess was developed without fail when live bacteria of which number within the order of 10(7) colony forming units were inoculated. Blood endotoxin concentration 24 hours after inoculation increased exponentially according to the inoculum size. However, that at the 7th postoperative day returned to the levels at zero time. Microscopic examination revealed a thick abscess wall, poor infiltration of inflammatory cells, and poor neovascularsis into the wall. These findings suggest that endotoxin is prevented from release into the blood stream since abscess contents are isolated by thick wall.

[Development of an experimental rat model of intraabdominal abscess by Escherichia coli alone. I. Materials for abscess formation]

To develop a new animal model of intraabdominal abscess by Escherichia coli alone, we reevaluated anaerobes and other additions which had been believed necessary to produce an intraabdominal abscess. We took the method of bacterial implantation by insertion of a double gelatin capsules containing microbes and the additions into the peritoneal cavity of male Wister rats. We examined the requirement of causative bacteria for an abscess including both aerobes and anaerobes, sterilized feces, and barium sulfate. It has been proven that a simple and well reproducible intraabdominal abscess can be developed without fail at the seventh day after inoculation although anaerobic bacteria, sterilized feces, and barium sulfate are not used. However, we have failed to produce an abscess without sterilized gauze fiber which should be a core of an abscess and is used instead of sterilized feces. This animal model will contribute to a major simplification of the original one heretofore in use, and is expected to serve as an aid to elucidate the mechanisms of abscess formation.

[Prediction of postoperative pulmonary hemodynamics for the second lobectomy after the contralateral lobectomy]

We presented 7 cases who were performed the second lobectomy for the second lung cancer after the first successful lobectomy on the contralateral lung (3 cases for right upper lobectomy + left lower lobectomy and 4 cases for right upper lobectomy + left lower lobectomy). In 6 patients, the predicted postoperative FEV1 estimated by multiplying the preoperative FEV1 by the fraction of perfusion to the contralateral lung was less than 800 ml/m2BSA, which is our first cut-off for identifying lung resection candidates. Unilateral pulmonary arterial occlusion test (UPAO) revealed that total pulmonary vascular resistance (TPVRI) in 3 of those 6 patients was lower than 700 dyne.sec.cm-5/m2BSA, our second cut-off for lung resection. More precise postlobectomy pulmonary hemodynamics in another 3 of those 6 patients were then estimated by adapting selective pulmonary occlusion test (SPAO). Since TPVRI during SPAO was lower than the cut-off value, it was suggested that second lobectomy would be feasible with low incidence of post operative cardiopulmonary complication. There was no serious complications in all 7 cases during their postoperative course. We believe that more precise prediction of postoperative pulmonary hemodynamics by adapting UPAO and SPAO could be one of the tools to minimumize postoperative cardiopulmonary complications in those patients needed second lobectomy for the second lung cancer after the first successful lobectomy on the contralateral lung even though their impaired lung fung function.

Transesophageal echocardiographic prediction of initially successful electrical cardioversion of isolated atrial fibrillation. Effects of left atrial appendage function

Left atrial appendage (LAA) flow velocities prior to electrical cardioversion were recorded using transesophageal pulsed Doppler echocardiography to predict initially successful cardioversion of isolated atrial fibrillation (AF). Patients with AF were placed into either a success group (19 patients) in which sinus rhythm was maintained for at least 2 days or a failure group (12 patients). The duration of AF was shorter in the success group. The maximum left atrial diameter was the same for the two groups. The maximum LAA area was smaller in the success group. The maximum forward and backward LAA velocities were greater in the success group, as were the mean forward and backward LAA velocities. In the patients with mean LAA flow velocities greater than 19 cm/sec, the success of cardioversion could be predicted with high sensitivity (80%) and specificity (88%). We conclude that the duration of AF, the maximum LAA area, and LAA flow velocities prior to cardioversion predict the initial recovery of sinus rhythm for isolated AF.

Atherogenic lipoprotein changes in the absence of hyperlipidemia in patients with chronic renal failure treated by hemodialysis

We compared plasma lipid and lipoprotein parameters between 210 chronic renal failure patients treated by hemodialysis and 223 age- and sex-matched healthy control subjects to examine whether atherogenic lipoprotein changes were present in hemodialysis patients in the absence of hyperlipidemia. The hemodialysis group showed higher levels of plasma triglycerides, very low density lipoprotein (VLDL) cholesterol, and intermediate density lipoprotein (IDL) cholesterol and a lower level of high density lipoprotein (HDL) cholesterol. Low density lipoprotein (LDL) cholesterol of the hemodialysis group was not elevated but their LDL was significantly more triglyceride-enriched than that of controls. Subjects were then divided into five categories according to their plasma triglyceride levels at an interval of 50 mg/dl, and comparison was made between the two groups in the same range of plasma triglycerides. Hemodialysis patients again showed higher levels of VLDL- and IDL-cholesterol, and lower levels of HDL-cholesterol than the control group even in the plasma triglycerides-matched comparisons. Similarly, higher VLDL- and IDL-cholesterol levels in hemodialysis patients were significant in plasma total cholesterol-matched subgroup comparisons. Multiple regression analysis indicated that the relationship between plasma lipid concentrations and individual lipoprotein levels were substantially altered in uremic state. The 95th percentile level of IDL-cholesterol in the nonuremic controls was 15 mg/dl, and 45% of hemodialysis patients exceeded this level. Decreased HDL-cholesterol levels < or = 35 mg/dl were seen in 6% of the control and 38% of the hemodialysis group. Elevated IDL-cholesterol and decreased HDL-cholesterol were persistently found in hemodialysis patients with normal lipid levels. It is concluded that hemodialysis patients exhibited more atherogenic lipoprotein profile than nonuremic subjects with comparable levels of plasma triglycerides and total cholesterol. Especially, increased IDL- and decreased HDL-cholesterol levels in hemodialysis patients persisted even at very low levels of plasma lipids. Since elevated IDL and decreased HDL-cholesterol are implicated in the progression of atherosclerosis, these findings are of clinical importance in the diagnosis of lipoprotein disorder in chronic renal failure.

[Effect of thoracoscopic procedure versus standard posterolateral/muscle-sparing thoracotomy on pulmonary lung function]

To understand the effects of thoracoscopic approach to thoracotomy on lung function, we investigated the changes in lung function after thoracoscopic operation (n = 7) and compared them to those after standard posterolateral (n = 5) or muscle-sparing thoracotomy (n = 6). In 18 patients with benign lung tumor in which surgical treatment resected in partial resection of the lung tissue, we measured TLC, VC, RV, FEV1.0, FEV1.0%, Peak Flow and DLco preoperatively and at 2, 4 weeks postoperatively. In the standard posterolateral or muscle-sparing thoracotomy groups, FVC, TLC, FEV1.0 and Peak Flow decreased to about 80% of preoperative value at 2 weeks. At 4 weeks after operation, these values showed to increase some what, but did not reach to the preoperative value. Whereas, the thoracoscopic procedure group, did not show the decrease in lung function through the time course. There was not significant different between standard posterolateral and muscle-sparing thoracotomy. We conclude that thoracoscopic approach is an useful technique to thoracotomy because of its minimizing after thoracotomy effect of lung function loss.

[Increase in pulmonary vascular permeability caused by increased expression of Mac-1 on the surface of polymorphonuclear leukocytes]

We studied the expression of adhesion molecules on the surface of human polymorphonuclear leukocytes (PMNs). The effects of mechanical stimulation were measured with a flow cytometer and pulmonary vascular injury due to accumulation of PMNs in the lungs was assessed by a gravimetric method. The accumulation of PMNs in the lungs was studied by measuring the amount of myeloperoxidase. PMNs were stimulated by gentle agitation in a glass container for 10 s. Mac-1 (CD11b/CD18) was upregulated on the surface of PMNs that were mechanically stimulated. When unstimulated PMNs were exposed to isolated rat lungs, the filtration coefficient did not change from that under baseline conditions. However, when mechanically stimulated PMNs were exposed to isolated rat lungs, the filtration coefficient was about 5 times higher than that measured at baseline. When mechanically stimulated PMNs treated with anti-CD18 antibody were used, the increase in the filtration coefficient was completely blocked. The assay of myeloperoxidase revealed that PMNs stuck to isolated rat lungs only after stimulated PMNs were added. We conclude that when the adhesiveness of PMNs is increased by mechanical stimulation, these cells adhere to pulmonary vessels and increase pulmonary vascular permeability.

Clinical application of pulsed Doppler tissue imaging for assessing abnormal left ventricular relaxation

Conventional assessment of left ventricular (LV) relaxation by calculating the time constant of LV pressure decay during the isovolumic diastole requires an invasive approach. Conversely, noninvasive parameters obtained by measuring isovolumic relaxation time and transmitral flow velocity often give inaccurate information. Using LV pressure curve, pulsed Doppler echocardiography, and pulsed Doppler tissue imaging in 38 patients with heart disease and 12 control subjects, we calculated the time constant and recorded transmitral flow velocity and motion velocities at the endocardial portions of the ventricular septum and LV posterior wall. Compared with the controls, patients exhibited a prolonged time constant, a decreased peak early diastolic velocity of the LV posterior wall, and a prolonged time interval from the second heart sound to the peak of the early diastolic wave. The time constant correlated well with the isovolumic relaxation time and various parameters calculated from the transmitral flow velocity, except in patients with elevated LV end-diastolic pressure. In all subjects, the time constant correlated negatively with the peak early diastolic velocity of the posterior wall and positively with the time from the second heart sound to the peak of the early diastolic wave. Thus, early diastolic parameters derived from the motion velocity of the LV posterior wall by pulsed Doppler tissue imaging were closely related to the time constant. This technique may allow noninvasive evaluation of abnormal LV relaxation in patients with various heart diseases.

Evaluation of left atrial appendage function by measurement of changes in flow velocity patterns after electrical cardioversion in patients with isolated atrial fibrillation

We investigated temporary changes in left atrial appendage (LAA) flow velocity patterns in patients undergoing electrical cardioversion for chronic isolated atrial fibrillation, and evaluated the role of active LAA contraction in directing blood flow to the left atrial main chamber and left ventricle. The study consisted of 26 patients with chronic isolated atrial fibrillation treated with electrical cardioversion and 20 normal controls in sinus rhythm. Using transthoracic and transesophageal Doppler echocardiography, we recorded transmitral, pulmonary venous, and LAA flow velocity patterns before, 24 hours, and 1 week after cardioversion in all subjects. In the 15 patients who underwent successful cardioversion, the maximal LAA area 24 hours after cardioversion was smaller than the area before cardioversion, whereas LAA ejection fraction during atrial systole and peak atrial systolic emptying velocity of the LAA flow were lower 24 hours after cardioversion than those in the control group. One week after cardioversion, maximal LAA area and LAA peak atrial systolic emptying velocity were restored to levels approximately equivalent to those in the control group, although LAA ejection fraction was lower than in the control group. Maximal LAA area and LAA peak atrial systolic emptying velocity correlated negatively and positively with LAA ejection fraction, respectively, 24 hours and 1 week after cardioversion. These results suggest that LAA and the left atrial main chamber show stunning 24 hours after cardioversion, and the atrial systolic emptying wave of LAA flow is generated by active LAA contraction.

Cross sectional echocardiographic demonstration of the mechanisms of abnormal interventricular septal motion in congenital total absence of the left pericardium

OBJECTIVE

To investigate the influence of the absence of the pericardium on the left ventricular wall, particularly on interventricular septal motion, using M mode and cross sectional short axis echocardiography in patients with congenital total absence of the left pericardium.

METHODS

21 patients with, congenital total absence of the left pericardium were divided into three groups according to the interventricular septal motion; systolic type (n = 6) with paradoxical motion during systole, diastolic type (n = 11) with abnormal posterior motion during mid to late diastole, and mixed type (n = 4) with paradoxical motion during systole and abnormal posterior motion during diastole.

RESULTS

On cross sectional short axis echocardiograms of the left ventricle, in the diastolic type the degree of angular displacement of the papillary muscles during end diastole to end systole showed excessive anticlockwise rotation about the long axis of the left ventricle without marked anteroposterior displacement. In the systolic type, there was shift of the left ventricle towards the anteromedial portion in systole and towards the posterolateral portion in diastole without significant rotation. There was a significantly positive correlation between the degree of angular displacement and the amplitude of diastolic interventricular septal motion during mid to late diastole in all patients.

CONCLUSIONS

There was abnormal interventricular septal motion during systole and diastole in patients with total absence of the left pericardium. Abnormal systolic motion was induced by anteroposterior displacement of the left ventricle, and abnormal diastolic motion by left ventricular rotation about the long axis of the heart during the cardiac cycle. Analysis using cross sectional echocardiography was useful for elucidating the mechanisms of abnormal interventricular septal motion.

The 'sail sound' and tricuspid regurgitation in Ebstein's anomaly: the value of echocardiography in evaluating their mechanisms

We describe a patient with Ebstein's anomaly in whom Doppler echocardiography was used to clarify the mechanism responsible for 'sail sound' and tricuspid regurgitation associated with this condition. Phonocardiography revealed an additional early systolic heart sound, consisting of a first low-amplitude component (T1) and a second high-amplitude component (T2, 'sail sound'). In simultaneous recordings of the tricuspid valve motion using M mode echocardiography and phonocardiography, the closing of the tricuspid valve occurred with T1 which originated at the tip of the tricuspid leaflets, while T2 originated from the body of the tricuspid leaflets. Using color Doppler imaging, the tricuspid regurgitant signal was detected during pansystole, indicating a blue signal during the phase corresponding to T1 and a mosaic signal during the phase corresponding to T2 at end-systole. Thus, 'sail sound' in patients with Ebstein's anomaly is not simply a closing sound of the tricuspid valve, but a complex closing sound which includes a sudden stopping sound after the anterior and/or other tricuspid leaflets balloon out at systole.

Tricuspid inflow and regurgitant flow dynamics after mitral valve replacement: differences relating to surgical repair of the tricuspid valve

BACKGROUND AND AIMS OF THE STUDY

Changes in tricuspid inflow and regurgitant flow dynamics were evaluated in patients with functional tricuspid regurgitation (TR) who underwent mitral valve replacement (MVR) with and without tricuspid annuloplasty (TAP).

METHODS

In a group of 30 patients, all with atrial fibrillation, 15 underwent TAP performed according to the modified De Vega technique; the remaining 15 did not undergo TAP. Patients were studied before and serially after surgery, using pulsed and color Doppler echocardiography. The mean follow up was 4.7 years in the TAP group and 5.1 years in the non-TAP group.

RESULTS

In the TAP group, immediately after surgery, the area of the TR jet decreased markedly, and the deceleration time of the tricuspid inflow velocity wave was significantly prolonged compared with that before surgery. By contrast, in the non-TAP group, both the area of the TR jet and deceleration time of tricuspid inflow velocity were virtually unchanged. The area of the TR jet remained small for a long period in the TAP group, but in non-TAP patients was increased in four cases over seven years, with two patients developing right-sided heart failure. Recent data showed the area of the TR jet to be significantly smaller, with maximum tricuspid inflow velocity significantly increased, and deceleration time of the tricuspid inflow velocity wave significantly prolonged in the TAP group compared with the non-TAP group.

CONCLUSIONS

In patients with functional tricuspid regurgitation undergoing MVR, concomitant TAP may cause mild tricuspid stenosis, but produces sustained preventive effects against TR. Careful follow up is needed in patients who have not undergone TAP, as TR is not markedly decreased and may even be exacerbated. Aggressive TAP is recommended in patients showing dilatation of the tricuspid annulus, even if TR is mild.

[A case of systemic origin of an aberrant artery to the basal segment of the lung]

We report on a rare case of systemic origin of an aberrant artery to the basal segment of the lung (Pryce I type intralobar pulmonary sequestration) that caused occasional bloody sputum. The patient was admitted to our hospital after an abnormal image was discovered in Chest X-ray film. The chest MRI showed an abnormal vessel originating from the descending aorta. The aortagram showed an abnormal artery originating from the descending aorta and entering the left lower lobe, and the left pulmonary angiogram revealed a poorly blood supply to the left basal segments. The preoperative diagnosis of systemic origin of an aberrant artery to the basal segment of the lung was given. The patient was subjected to surgical treatment. During surgery, it was found that the abnormal artery, 12 mm in diameter, which was connected from the descending aorta to the left basal segments. The abnormal artery was dissected, and the left basal segments was removed. The postoperative course was uneventful.

[Role of leukotriene B4 in monocrotaline-induced pulmonary hypertension]

Monocrotaline (MCT) causes lung inflammation and chronic pulmonary hypertension associated with lung vascular thickening in rats. We hypothesized that leukotriene B4 (LTB4) and LTB4-induced accumulation of leukocytes in the lung play a role in MCT-induced lung disease, and therefore measured LTB4 and myeloperoxidase (MPO) levels in lung tissue of MCT-treated rats. Next, we examined the effect of an orally active LTB4 receptor antagonist (ONO4057) on MPO levels in lung tissue, on pulmonary hypertension, and on pulmonary vascular remodeling induced by MCT. Lung LTB4 and MPO levels had increased by 3 days after MCT injection. In the ONO4057-treated MCT rats, lung MPO levels were significantly lower than in the rats given MCT but not ONO4057. By the third week after injection. MCT had caused increases in mean pulmonary arterial pressure, in the ratio of right ventricular weight to left ventricle+septum weight (RV/[VS + S]), and in media wall thickness of the muscular arteries of the lung. Treatment with ONO4057, either for 3 weeks or during the first week after MCT injection, significantly reduced pulmonary hypertension, right ventricular hypertrophy, and lung vascular thickening induced by MCT. These results indicate that ONO4057 reduces both the accumulation of leukocytes in lung tissue and the chronic pulmonary hypertension induced by MCT, and they suggest a role for LTB4 in the inflammatory process that contributes to pulmonary hypertension and lung vascular remodeling induced by MCT in rats.

Relation of disease activity during chronic hepatitis C infection to complexity of hypervariable region 1 quasispecies

We studied the heterogeneity in the E2/NS1 hypervariable region 1 of the hepatitis C virus (HCV) genome in relation to the natural course after infection. The subjects were composed of 38 chronic hepatitis C carriers who had been followed for 9 to 218 months after the onset of non-A, non-B (type C) hepatitis, being tested monthly for serum alanine aminotransferase levels. The complexity of the sequence heterogeneity was assessed by single-strand conformation polymorphism analysis. The quasispecies complexity had no relation to the route of infection, the time from infection and the duration of aminotransferase elevation after the onset. However, it had a significant relationship with the degree of aminotransferase elevation in the course of the disease. The quasispecies complexity was directly correlated with the first peak of serum aminotransferase at the onset (r = .48, P < .01) and the mean aminotransferase levels during the period of persistent aminotransferase elevation (r = .58, P < .01). Twenty-three of the 38 patients were further followed for 24 months with biweekly alanine transaminase (ALT) tests. Their aminotransferase levels remained within the normal range during follow-up, and no significant change was seen in the quasispecies complexity after this asymptomatic period. However among the 23 patients, the quasispecies complexity increased in six cases (26%) and decreased in five (22%). A significant direct relation was seen between changes in the quasispecies complexity and the mean aminotransferase levels during the asymptomatic period (r = .55, P = .01). These findings suggest that the development of the HCV quasispecies nature may be related to the severity of the hepatitis in the course of infection.

Inhibition of lymph node metastasis by an anti-angiogenic agent, TNP-470

We assessed the inhibitory action of TNP-470 on lymph node metastasis in a metastatic model system using athymic nude mice. Mice were injected subcutaneously with 5 x 10(6) HT-1080 cells in the right groin. TNP-470 (10, 30 and 100 mg kg-1) was injected subcutaneously nine times in total every other day from the 7th day after tumour inoculation. Axillar and inguinal lymph nodes were dissected, and DNA was extracted 5 weeks after tumour inoculation. Specific detection of a human beta-globin-related sequence in metastasized human tumour cells in nude mice was done by the polymerase chain reaction (PCR) technique and analysed by Southern blotting. Anti-tumour effects on primary sites were seen only in the 100 mg kg-1 treatment group. Lymph node metastasis of transplanted HT-1080 cells was seen in all mice of the no treatment group (5/5). On the other hand, incidences of lymph node metastasis in treated mice were 2/4 mice (100 mg kg-1, 2/5 mice (30 mg kg-1) and 4/5 mice (10 mg kg-1). The inhibition ratios of lymph node metastasis were 82.3% at 10 mg kg-1, 97.2% at 30 mg kg-1 and 97.5% at 100 mg kg-1 respectively. This agent may be useful to inhibit lymph node metastasis.

Concealed left ventricular hypertrophy and diastolic dysfunction in hypertrophic cardiomyopathy in the presence of acute left ventricular volume overload. A case report

We report a patient in whom hypertrophic cardiomyopathy, with both left ventricular hypertrophy and diastolic dysfunction, was masked by acute severe aortic regurgitation and marked left ventricular dilation. Upon admission, 1) two-dimensional echocardiogram of the left ventricle revealed a dynamic and flail vegetation on the aortic right coronary cusp and marked left ventricular dilation, 2) a massive aortic regurgitant signal was recorded by color Doppler flow imaging, and 3) transmitral flow velocity by pulsed Doppler echocardiogram revealed a pseudonormalization. However, symmetric hypertrophy of the left ventricular wall, a decrease in early diastolic wave and a compensatory increase in atrial systolic wave of the transmitral flow velocity appeared after successful aortic valve replacement.

History of vitamin D treatment of renal osteodystrophy

Vitamin D treatment was tried when renal osteodystrophy was first recognized in the early 20th century, using vitamin D2, D3, or dihydrotachysterol. Large doses of vitamin D2 or D3 (150,000-500,000 IU) were prescribed by monitoring serum calcium, phosphate, and alkaline phosphatase. After the discovery of 1,25-dihydroxycholecalciferol, this compound or 1 alpha-hydroxycholecalciferol was applied to the treatment of renal osteodystrophy. In a preclinical study, especially of 1 alpha-hydroxycholecalciferol, nephritogenoside nephritis was the most responsive condition. These active vitamin D preparations are now widely used in patients with chronic renal failure under hemodialysis. Other active vitamin D compounds, such as hexafluoro-1,25-dihydroxycholecalciferol and 22-oxacalcitriol, are also under investigation.

Relationship between the angiotensin converting enzyme gene polymorphism and the effects of enalapril on left ventricular hypertrophy and impaired diastolic filling in essential hypertension: M-mode and pulsed Doppler echocardiographic studies

OBJECTIVE

To investigate the relationship between the angiotensin converting enzyme (ACE) gene polymorphism and the effects of the ACE inhibitor enalapril on left ventricular hypertrophy and impaired diastolic filling.

DESIGN AND METHODS

Enalapril (5-10 mg/day) was administered for 12 months to 60 previously untreated patients with essential hypertension. M-mode and pulsed Doppler echocardiography were performed before and after treatment, and changes in various parameters after treatment with enalapril were examined. ACE gene polymorphism was examined by the polymerase chain reaction method and the patients were classified as having the 190 bp deletion homozygous (DD) genotype, the 490 bp insertion homozygous (II) genotype or the 490 bp insertion 190 bp deletion heterozygous (ID) genotype.

RESULTS

The DD genotype was observed in 10 patients (17%), the ID genotype in 24 patients (40%) and the II genotype in 26 patients (43%). Plasma ACE activity before treatment with enalapril was significantly higher in seven patients with DD genotype than it was in 18 patients with ID genotype and in 14 patients with II genotype. In all of the 60 patients, the left ventricular mass index, the peak atrial systolic velocity:early diastolic velocity ratio and the deceleration time from the peak of the early diastolic wave to the baseline in transmitral flow velocity were decreased significantly after treatment with enalapril. The changes in left ventricular mass index and atrial systolic velocity:early diastolic velocity ratio after enalapril administration were significantly greater in the DD genotype group than they were in the other two genotype groups.

CONCLUSION

Enalapril-induced regression of left ventricular hypertrophy and improvement in left ventricular impaired diastolic filling were significantly greater in the DD genotype group than they were in the ID and II genotype groups, suggesting that the circulating and tissue renin-angiotensin systems, particularly the former system, are most active in hypertensive patients with the DD genotype.