Hamiltonian Engineering with Multicolor Drives for Fast Entangling Gates and Quantum Crosstalk Cancellation

Quantum computers built with superconducting artificial atoms already stretch the limits of their classical counterparts. While the lowest energy states of these artificial atoms serve as the qubit basis, the higher levels are responsible for both a host of attractive gate schemes as well as generating undesired interactions. In particular, when coupling these atoms to generate entanglement, the higher levels cause shifts in the computational levels that lead to unwanted ZZ quantum crosstalk. Here, we present a novel technique to manipulate the energy levels and mitigate this crosstalk with simultaneous off-resonant drives on coupled qubits. This breaks a fundamental deadlock between qubit-qubit coupling and crosstalk. In a fixed-frequency transmon architecture with strong coupling and crosstalk cancellation, additional cross-resonance drives enable a 90 ns CNOT with a gate error of (0.19±0.02)%, while a second set of off-resonant drives enables a novel CZ gate. Furthermore, we show a definitive improvement in circuit performance with crosstalk cancellation over seven qubits, demonstrating the scalability of the technique. This Letter paves the way for superconducting hardware with faster gates and greatly improved multiqubit circuit fidelities.

Demonstration of a High-Fidelity cnot Gate for Fixed-Frequency Transmons with Engineered ZZ Suppression

Improving two-qubit gate performance and suppressing cross talk are major, but often competing, challenges to achieving scalable quantum computation. In particular, increasing the coupling to realize faster gates has been intrinsically linked to enhanced cross talk due to unwanted two-qubit terms in the Hamiltonian. Here, we demonstrate a novel coupling architecture for transmon qubits that circumvents the standard relationship between desired and undesired interaction rates. Using two fixed frequency coupling elements to tune the dressed level spacings, we demonstrate an intrinsic suppression of the static ZZ while maintaining large effective coupling rates. Our architecture reveals no observable degradation of qubit coherence (T_{1},T_{2}>100  μs) and, over a factor of 6 improvement in the ratio of desired to undesired coupling. Using the cross-resonance interaction, we demonstrate a 180 ns single-pulse controlled not (cnot) gate, and measure a cnot fidelity of 99.77(2)% from interleaved randomized benchmarking.

Tunable Coupling Architecture for Fixed-Frequency Transmon Superconducting Qubits

Implementation of high-fidelity 2-qubit operations is a key ingredient for scalable quantum error correction. In superconducting qubit architectures, tunable buses have been explored as a means to higher-fidelity gates. However, these buses introduce new pathways for leakage. Here we present a modified tunable bus architecture appropriate for fixed-frequency qubits in which the adiabaticity restrictions on gate speed are reduced. We characterize this coupler on a range of 2-qubit devices, achieving a maximum gate fidelity of 99.85%. We further show the calibration is stable over one day.

New insight of Arctic cloud parameterization from regional climate model simulations, satellite-based and drifting station data

Cloud observations from the CloudSat and CALIPSO satellites helped to explain the reduced total cloud cover (Ctot) in the atmospheric regional climate model HIRHAM5 with modified cloud physics. Arctic climate conditions are found to be better reproduced with (1) a more efficient Bergeron-Findeisen process and (2) more generalized subgrid-scale variability of total water content. As a result, the annual cycle of Ctot is improved over sea ice, associated with an almost 14% smaller area average than in the control simulation. The modified cloud scheme reduces the Ctot bias with respect to the satellite observations. Except for autumn, the cloud reduction over sea ice improves low-level temperature profiles compared to drifting station data. The HIRHAM5 sensitivity study highlights the need for improving accuracy of low-level (< 700m) cloud observations, as these clouds exert a strong impact on the near-surface climate.

Anti-Gal titers in healthy adults and inflammatory bowel disease patients

INTRODUCTION

ALPHA-GAL is a glycoconjugate present on cell membranes of mammals and bacteria but not humans who display anti-Gal antibodies (AB) in high titers provoked by the commensal gut flora. In the present study, we sought to determine the longitudinal course of alpha-Gal specific AB titers of all isotypes over 8 weeks among healthy adult subjects. Furthermore, we hypothesized that inflammatory bowel disease (IBD) patients display increased anti-Gal titers.

MATERIALS AND METHODS

We drew serum from healthy probands (n=20) weekly for 8 weeks and obtained plasma samples of from patients suffering from Crohn's disease (n=20) and ulcerative colitis (n=20). We measured anti-Gal ABs of all isotypes and total immunoglobulin (Ig) content using an enzyme-linked immunosorbent assay technique. For statistical evaluation of the longitudinal titers, we calculated confidence intervals for the slopes of a random intercept model, comparing variances between and within the probands. For group comparisons, we performed paired student t-tests and Pearson correlations.

RESULTS

Alpha-Gal specific IgG, IgM, IgD, and IgA titers remained unvaried within a narrow range upon longitudinal observation. Most probands did not display alpha-Gal specific IgE ABs. Crohn's disease patients showed highly increased alpha-Gal-specific IgA titers compared with control subjects (P<.01).

CONCLUSION

Apart from IgE, alpha-Gal-specific ABs of all isotypes remained constant over longer time periods in healthy subjects. Thus, significant titer changes actually represent increased antigen exposure and a specific anti-alpha-Gal response. Crohn's disease patients display increased anti-Gal IgA titers compared with healthy controls, which reflects a chronically impaired mucosal gut barrier in this patient cohort.

The Antiproliferative Effect of Calcitriol on Breast Cancer Cell Lines Depends on Vitamin D Receptor Status and the Expression of Prostaglandin Metabolizing Enzymes

Background: Both first studies in prostate cancer and our results in breast cancer suggest a link between vitamin D and prostaglandin metabolism. There is a growing body of evidence that COX-2 expression is a fundamental step in breast cancer pathogenesis acting through prostaglandin-dependent and independent mechanisms. The antiproliferative effects of calcitriol (1,25(OH)2D3) mediated via the vitamin D receptor (VDR), render the biologically active form of vitamin D a promising target in breast cancer therapy.Materials and methods: The expression of VDR, COX-2 and 15 PGDH was determined by Western blot in MCF-10F cells, a human benign epithelial cell line, in MCF-7 cells, a moderate invasive and in MDA-MB-231 cells, a highly invasive breast cancer cell line. Measurement of basal PGE2 secretion was performed with ELISA. The influence of calcitriol on cell proliferation was determined by 5-bromo-2-deoxyuridine (BrDU) incorporation (BrDU ELISA). In addition we examined the effect of calcitriol on COX-2, 15 PGDH and VDR protein levels compared to untreated cells.Results: After 72 hours the proliferation of MCF-10F cells was dose-dependent inhibited to 0.83± 0.1 by 1 nM calcitriol. Concurrently, we observed a reduction of COX-2 expression to 0.63± 0.05 as compared to the untreated control group, but we also found a reduction of 15 PGDH to 0.73± 0.16. These effects were associated with a higher expression of VDR to 1.64± 0.16. Interestingly, MCF-7 cell growth was reduced to 0.52± 0.04 by 10 nM calcitriol and to 0.7± 0.06 by 1 nM. These effects do not seem to be associated with COX-2 and 15 PGDH and are independently of VDR. VDR was detected neither in stimulated nor in unstimulated cells. A PGE2 secretion could not be detected by ELISA. In contrast, we found no effect on cell growth, COX-2 and 15-PGDH expression of the MDA-MB-231 cells when treated by calcitriol (10 nM and 1 nM). Although PGE2 was synthesized 2.3-fold more by MDA-MB-231 cells than MCF-10F cells; the COX-2 expression was consistent with the MCF-10F cells, but 15-PDGH was expressed about 50 % less. As we have shown in MCF-7 cells, an expression of the VDR could not be detected.Conclusions: The growth inhibiting effect of calcitriol in MCF10F cells is associated with the increasing expression of VDR. and a remaining question is whether the loss of VDR goes along with the invasiveness of the breast cancer cell lines. Additionally, we suggest that the invasiveness of the breast cells is abetted by the increased COX-2 expression (MCF-7) or by the decreased expression of 15 PGDH (MDA-MB-231). These results suggest even more a link between vitamin D and prostaglandin metabolism and therefore a possible synergism between COX-2 inhibition and calcitriol in breast cancer cells.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 5155.

[Restriction of salt intake in the whole population promises great long-term benefits]

Restricting salt intake not only leads to a decrease of blood pressure and a reduction in the incidence of arterial hypertension but also to a fall in cardiovascular morbidity and mortality. But high sodium intake is not only a risk factor for hypertension but also for cardiovascular diseases. Moderate reduction of daily salt intake in the entire population of Germany from the present level of 8-10 mg to 5-6 mg is of great benefit for disease load and to the economy. Any possible risk for a few groups of persons is predictable and can be coped with. General sodium reduction cannot be achieved only by individual advice, instruction or information campaigns but requires a reduction in the sodium content of industrially processed foods, in fast-food chains, restaurants and canteens because they supply 80% of total daily sodium intake. To achieve the target of restricting the sodium intake of the whole population it is recommended that an interdisciplinary and interprofessional task force, "Less salt for all" be established. This is to bring together the expertise of scientific societies and institutions that see their main task in the reduction of cardiovascular mortality and morbidity by primary prevention. Individual prevention in patients at risk can be very significantly improved by population-related preventive measures. These include, in addition to general limitation of sodium intake, continuing change in lifestyle.

Analysis of a spacecraft life support system for a Mars mission

This report summarizes a trade study conducted as part of the Fall 2002 semester Spacecraft Life Support System Design course (ASEN 5116) in the Aerospace Engineering Sciences Department at the University of Colorado. It presents an analysis of current life support system technologies and a preliminary design of an integrated system for supporting humans during transit to and on the surface of the planet Mars. This effort was based on the NASA Design Reference Mission (DRM) for the human exploration of Mars [NASA Design Reference Mission (DRM) for Mars, Addendum 3.0, from the world wide web: http://exploration.jsc.nasa.gov/marsref/contents.html.]. The integrated design was broken into four subsystems: Water Management, Atmosphere Management, Waste Processing, and Food Supply. The process started with the derivation of top-level requirements from the DRM. Additional system and subsystem level assumptions were added where clarification was needed. Candidate technologies were identified and characterized based on performance factors. Trade studies were then conducted for each subsystem. The resulting technologies were integrated into an overall design solution using mass flow relationships. The system level trade study yielded two different configurations--one for the transit to Mars and another for the surface habitat, which included in situ resource utilization. Equivalent System Mass analyses were used to compare each design against an open-loop (non-regenerable) baseline system.

Effects of space flight, clinorotation, and centrifugation on the substrate utilization efficiency of E. coli

Cultures of Escherichia coli grown in space reached a 25% higher average final cell population than those in comparably matched ground controls (p<0.05). However, both groups consumed the same quantity of glucose, which suggests that space flight not only stimulated bacterial growth as has been previously reported, but also resulted in a 25% more efficient utilization of the available nutrients. Supporting experiments performed in "simulated weightlessness" under clinorotation produced similar trends of increased growth and efficiency, but to a lesser extent in absolute values. These experiments resulted in increases of 12% and 9% in average final cell population (p<0.05), while the efficiency of substrate utilization improved by 6% and 9% relative to static controls (p=0.12 and p<0.05, respectively). In contrast, hypergravity, produced by centrifugation, predictably resulted in the opposite effect--a decrease of 33% to 40% in final cell numbers with corresponding 29% to 40% lower net growth efficiencies (p<0.01). Collectively, these findings support the hypothesis that the increased bacterial growth observed in weightlessness is a result of reduced extracellular mass transport that occurs in the absence of sedimentation and buoyancy-driven convection, which consequently also improves substrate utilization efficiency in suspended cultures.

Underutilizers of mammography screening today: characteristics of women planning, undecided about, and not planning a mammogram

Using concepts from the Precaution Adoption Process Model, we identified behavioral factors, sociodemographic and psychosocial variables, and beliefs about breast cancer that discriminated among women at different stages with regard to their intention to obtain mammography screening. An independent survey company conducted telephone interviews with 2,507 women aged 50 to 80 who were identified as underutilizers of mammography screening. Each underutilizer was assigned to one of three stages with regard to intention to get a mammogram: (a) definitely planning, (b) thinking about, and (c) not planning. Estimated actual risk of breast cancer, perceived risk to breast cancer, worry about breast cancer, and fear of learning from a mammogram that one has breast cancer were variables found to be significantly associated with intention to obtain a mammogram for several subgroups of underutilizing women. There are significant behavioral and psychosocial variables, beliefs and feelings about breast cancer, and demographic characteristics that distinguish underutilizing women at various stages with regard to intention to obtain mammography screening. Our findings provide new information that could help the health care professional motivate women who are not planning to utilize this preventive health measure to become regular utilizers.

[Comparison of invasive blood pressure measurement in the aorta with indirect oscillometric blood pressure measurement at the wrist and forearm]

Indirectly measured blood pressure at the wrist or upper arm was compared with directly measured values in the aortic arch during routinely performed diagnostic cardiac catheterization in 100 patients (31-80 years, mean 59.3 years, 60% males). The noninvasive measurements were carried out by oscillometric devices, NAiS Blood Pressure Watch for measurements at the wrist, and Hestia OZ80 at the upper arm. Systolic blood pressure measured at the wrist was 4.3 +/- 14.1 mm Hg, and the diastolic value 6.0 +/- 8.9 mm Hg higher than when measured at the aortic arch; the difference was significant in both cases. Correlation coefficients were 0.85 for systolic and 0.71 for diastolic blood pressure. In 16% of the patients the systolic blood pressure at the wrist differed more than +/- 20 mm Hg. The diastolic blood pressure at the wrist measured more than +/- 20 mm Hg higher than in the aorta in 5% of the patients. At the upper arm mean systolic values were not different to the aorta. The diastolic pressure was 9.3 +/- 9.8 mm Hg higher in the aorta than at the upper arm. To verify the accuracy of values measured with the NAiS Blood Pressure Watch compared with the standard technique at the upper arm, sequential measurements were made at wrist and ipsilateral upper arm in the same group of 100 patients. The systolic blood pressure at the left wrist was 3.4 +/- 13.3 mm Hg higher and the diastolic pressure 3.8 +/- 9.5 mm Hg lower than at the upper arm. Only 53% of systolic values lay within a range of +/- 10 mm Hg. The correspondence between wrist and upper arm values was better for diastolic blood pressure, the values differing by less than +/- 10 mm Hg in two-thirds of patients. Self-measurement of arterial blood pressure with an oscillometric device at the wrist can be recommended only in individual cases with a difference of simultaneously measured values at the upper arm of less than +/- 10 mm Hg for systolic and diastolic blood pressures. The standard method for indirectly measuring arterial blood pressure remains the measurement at the upper arm site, which nevertheless showed a systolic pseudohypertension (deviation of more than 10 mm Hg) in comparison to the invasively measured values in 15% of our selected patients and a diastolic pseudohypertension (deviation of more than 15 mm Hg) in 23% of the patients.

[Treatment of hypertension with a fixed calcium antagonist-diuretic combination. Observations from treatment of 5,595 patients]

METHOD

In an observational study lasting 6 months, 5,595 patients with essential hypertension were treated with a combination of a calcium antagonist and a diuretic, with the aim of testing the efficacy and safety of the drug. Some 63.8% oft the patients had already received anti-hypertensive treatment; 67.3% of the patients also had accompanying diseases. Treatment was begun with a single daily tablet comprising 160 mg verapamil, 50 mg triamterene and 25 mg hydrochlorothiazide (Veratide), and the dose could be reduced to one-half or increased to two daily as indicted by the response of the blood pressure.

RESULTS

At the end of 6 months of treatment, the overall groups showed a decrease in both systolic and diastolic blood pressure of 15.2% (26/15 mmHg). Breakdown oft the patients into various age groups revealed no differences in the results. Responder rates varied between 62.0 and 71.8%. Among patients with isolated systolic hypertension, the response rate was 66.4%. In this form of hypertension only the systolic blood pressure was lowered. During the course of treatment, 6.8% of the patients developed side effects, which were severe in 0.9% of the cases. In only 143 of the 5,595 patients did the treatment have to be broken off.

CONCLUSIONS

The efficacy and safety oft the combination preparation investigated have been confirmed under doctor's office conditions. The decrease in diastolic blood pressure was more marked among smokers than among non-smokers.

In-vivo investigation of material quality of bone tissue by measuring apparent phalangeal ultrasound transmission velocity

The square of ultrasound transmission velocity in a material is related to the modulus of elasticity, which is known to be an indicator of stability in bone. The aim of our study was to use ultrasound transmission velocity to obtain information about the material properties of bone tissue, keeping other factors possibly influencing ultrasound transmission as constant as possible. Apparent phalangeal ultrasound transmission velocity (APU) measured in 54 isolated, fresh pig phalanges was shown to be independent of bone mineral density (BMD) measured by SPA. Fastest sound transmission led exclusively through cortical bone so that intertrabecular connectivity in spongious bone could not influence the result. In humans APU was measured in the mediolateral direction at the midphalanx of the middle finger. In 53 healthy subjects (15-81 years old; 27 women, 26 men), there was a decrease of APU with age (r = -0.30, p < 0.05). Further, when comparing the results of both hands intraindividually almost identical values indicated constant intraindividual architecture of bone at this location. There was no evidence for a relation of APU to physical load comparing dominant and nondominant hand and relating the results to subjectively estimated physical load. In a second group of 43 perimenopausal women (47-60 years old), APU, which again decreased with age (r = -0.33, p < 0.05), was found not to be correlated to BMD measured by SPA at the distal forearm (cortical bone).(ABSTRACT TRUNCATED AT 250 WORDS)

A case study in planning for public health education: the organ and tissue donation experience

The chasm between the supply and demand of donated organs and tissues continues to grow despite widespread public awareness of transplantation and numerous efforts to educate the public about organ donation. It is fast becoming a significant public health problem in this country. The need for more effective public education is well documented in the literature on transplantation and is a primary objective of organizations in the transplant field. In response to this need, the Division of Organ Transplantation in the Health Resources and Services Administration of the Public Health Service initiated a project to examine the nature and scope of donation education initiatives throughout the country, to identify shortcomings, and to suggest ways the Federal Government could contribute to the effectiveness of public education in organ and tissue donation. The project resulted in the development of a protocol that also is applicable to other health education programs. Its major steps consisted of assessing the status of donation-related public education in the United States, identifying existing needs in donation education by applying principles learned from other public health education programs, and identifying roles that could be assumed to help strengthen the American public's commitment to organ and tissue donation. These roles, which could be adopted by an transplant-related organization, were as broker of knowledge, producer of educational strategies, energizer through communications research, and catalyst by bringing together other groups. This approach to needs assessment and planning may provide useful insights both for those concerned with transplants and for professionals conducting education campaigns related to other public health issues.

[The value of diuretics in monotherapy of hypertension]

AIM

To represent the usefulness of thiazide diuretics as monotherapy of primary hypertension.

MAIN POINTS

Moderate doses of thiazide diuretics can produce a reduction in blood pressure equal to that of beta blockers, calcium antagonists and ACE inhibitors, and achieve an equally high response rate. The advantages and disadvantages of the specific action profile of these diuretics are described. Discussions about the reduction in cardiovascular mortality is represented and practical conclusions drawn. The specific indications for monotherapy with thiazide diuretics include systolic, diastolic and isolated systolic hypertension in the elderly hypertensive, and hypertension in NYHA III and IV cardiac insufficiency. Suggestions for their use in practice are given.

Regression of left ventricular hypertrophy during long-term antihypertensive treatment--a comparison between felodipine and the combination of felodipine and metoprolol

Seventy-six hypertensive patients with left ventricular hypertrophy (LVH) were randomized to receive felodipine or felodipine plus metoprolol in a double-blind parallel-group study. The doses of each treatment regimen were titrated to obtain a diastolic blood pressure (BP) of less than 95 mmHg. The duration of the treatment was 9 months. At the end of the study, BP was significantly reduced in both groups, and the reduction did not differ between the groups. Left ventricular posterior wall and septum thickness were significantly and similarly reduced in both groups. Left ventricular systolic and diastolic end diameters were not significantly changed. Left ventricular mass (LVM) was significantly and similarly reduced in both treatment groups, as was the ratio of LVM and left ventricular end diastolic volume. In conclusion, felodipine and the combination of felodipine and metoprolol reduced left ventricular hypertrophy to the same extent when BP was similarly reduced.

Management of hypertension in actively exercising patients. Implications for drug selection

In general, rises in systolic blood pressure to over 200 mm Hg during exercise with a workload of 100W are regarded as pathological. Excessive exercise blood pressure values are to be expected in principle in all hypertensives. However, there are so far no generally accepted criteria for diagnosis of isolated systolic exercise hypertension (with normal values of resting blood pressure). The incidence of isolated systolic exercise hypertension is estimated to be about 10% of a selected population. In patients with excessive rises in blood pressure during exercise who want to engage actively in sport, general measures (reduction of obesity, restriction of alcohol and salt intake) and endurance training should be recommended initially. For endurance training, sporting activities that involve dynamic exercise are to be recommended (walking, running, mountain hiking, cycling, swimming, cross-country skiing). Activities involving isometric exercise (rowing, diving, tennis) and sport of a competitive nature are not suitable. In moderately severe and severe hypertension (diastolic blood pressure values in excess of 105 mm Hg), sporting activities and endurance training are contraindicated. If the exercise blood pressure values cannot be lowered below 220 mm Hg with the general measures mentioned, pharmacotherapy is to be considered. The drugs of choice for suppressing excessive rises in blood pressure during exercise are beta-blockers. In this group, beta 1-blockers are to be preferred to non-selective beta-blockers because of the metabolic neutrality of the former. beta-Blockers without intrinsic sympathomimetic activity (ISA) lower the blood pressure-pulse rate product more effectively than beta-blockers with ISA. Alternatively, calcium antagonists of the verapamil type and ACE inhibitors can be employed.(ABSTRACT TRUNCATED AT 250 WORDS)

Noninvasive PtcO2 initial slope index and invasive PtcO2 arterial index as diagnostic criterion of the state of peripheral circulation

Transcutaneous PO2 (PtcO2), PaO2, PtcO2 arterial index (ARI; PtcO2/PaO2), and the initial slope index (ISI; [delta PO2/min]/starting PtcO2) were measured in 42 healthy volunteers, 12 patients with stable circulation and respiratory insufficiency, and ten patients with insufficient peripheral circulation in cardiogenic shock in order to investigate whether ARI and ISI can be used to detect insufficient circulation. The ISI was measured by placing a PtcO2 electrode on the forearm and interrupting blood flow by inflating a cuff until the PtcO2 dropped to zero. After releasing the cuff pressure, the initial slope of the PtcO2 trace was determined in order to calculate the ISI. In the PtcO2 range between 40 and 100 torr, the ARI and ISI did not depend on the PtcO2 magnitude. In all groups, the ISI behaved similarly to the ARI. We conclude that the noninvasive ISI and invasive ARI are able to differentiate between stable and insufficient peripheral circulation (ISI less than 0.75, ARI less than 0.8; p less than .001).

[Differential therapy of exercise hypertension]

Criteria for the diagnosis of exercise hypertension have not yet been established. Published values for blood pressure increase during dynamic exercise in normotensive healthy persons differ greatly dependent on age, sex, heart frequency and load of dynamic exercise. Upper normal systolic values during exercise reach levels between 200 and 230 mm Hg. The incidence of exercise hypertension is therefore reported to range from 1 to 10% of the total population. Follow-up studies show that 10 to 60% of persons with isolated exercise hypertension proceed to chronic arterial hypertension. No results are available on exercise hypertension as a risk factor in contrast to the well-known link between increased systolic and diastolic casual blood pressure and cardiovascular diseases. The development of left-ventricular hypertrophy depends mainly on the average systolic blood pressure during a 24-hour period. Peak values of systolic blood pressure during the day or blood pressure variability are less important. Drug treatment of isolated exercise hypertension is not generally accepted. Non-drug treatment is to be preferred, e.g. weight reduction in overweight, dietary sodium restriction and endurance training. Drug treatment must be considered, if non-drug treatment is unsuccessful and/or risk factors, for example hypercholesterolemia, diabetes, cigarette smoking, or complications of target organs, i.e. coronary heart disease or cerebral infarction, do exist. In antihypertensive treatment of increased exercise blood pressure, the influence of the drugs on the hemodynamic and metabolic parameters must be observed, especially in patients with concomitant coronary heart disease. Increases in blood pressure due to dynamic exercise are better attenuated by antihypertensive drugs than those caused by isometric exercise. The drugs of choice are beta-blockers, preferably beta 1-blockers without ISA. Alternatively, calcium antagonists of the verapamil-type or ACE-inhibitors may be used. In contrast to other antihypertensive drugs, labetalol, calcium antagonists and ACE-inhibitors have no influence on the exercise-induced increase of cardiac index and therefore little effect on the work capacity of the circulatory system.

[Primary hypoaldosteronism, pseudo-hypoaldosteronism and distal tubular acidosis]

Aldosterone deficiency is caused by various defects of aldosterone biosynthesis in the adrenal gland or hyporeninism. The most important symptoms are hyponatremia and hyperkalemia. These electrolyte disturbances are also found in pseudohypoaldosteronism. Pseudohypoaldosteronism type I is characterized by insensitivity of the distal nephron for aldosterone. Hyperabsorption of chloride in the distal nephron leads to pseudohypoaldosteronism type II, which is linked with hypertension, whereas blood pressure in the other mentioned disorders is decreased. Renal tubular acidosis, mainly type 4, with impaired production of ammonia due to hyperkalemia, is frequently observed in hypoaldosteronism and both types of pseudohypoaldosteronism as well. The therapeutic regimen is different: low doses of fludrocortisone in hypoaldosteronism, potassium restriction, sodium bicarbonate and loop diuretics in type I of pseudohypoaldosteronism, and sodium restriction and chloruretic diuretics (thiazide) in type II of pseudohypoaldosteronism. In some cases hyperkalemia requires the use of potassium-binding resins.

[Primary hypoaldosteronism and secondary pseudo-hypoaldosteronism]

We observed a 23-year-old man with pronounced hyperkalemia (max. 6.8 mmol/l) and hyponatremia (min. 112 mmol/l), which had been existent for 3 years without complaint except a transitory psychorganic syndrome due to hyponatremia. Physical examination showed no abnormality except hypotension (blood pressure 100/70 mmHg). Renal function tests were normal. Fractional clearance of sodium was significantly increased (0.8%), whereas that of potassium was decreased (2.4%). Plasma renin activity was tripled and rose after furosemide. Plasma aldosterone was lowered and showed no rise after furosemide. Suppression of plasma renin and aldosterone by saline infusion was normal. Pressor dose of angiotensin II was increased (17,9 ng AT II/kg/min). Urinary excretion of aldosterone and its conjugates was below normal, and aldosterone precursors were within normal range. The findings were interpreted as selective primary hypoaldosteronism caused by corticosterone methyl oxidase defect type II. However, neither fludrocortisone (0.5 mg/day) nor sodium chloride (200 mmol/day) led to a normalization of sodium and potassium in plasma. Additional pseudohypoaldosteronism was thus assumed. Aldosterone infusion (3 mg in 1 h) decreased renal excretion of sodium; potassium excretion failed, however, to increase in contrast to its pattern in normal man. These findings resemble additional pseudohypo-aldosteronism of type II. After 8 weeks' application of additional 80 mmol sodium (as sodium bicarbonate) plasma sodium and potassium showed normal values under combined treatment with fludrocortisone (0.1 mg/day) and sodium bicarbonate (80 mmol/day). It is to be assumed that the patient suffers from a reduced aldosterone biosynthesis in the presence of an additional transitory secondary pseudohypoaldosteronism.

[R-wave amplitude during left ventricular volume changes in healthy hearts]

The relationship between R-wave amplitude and left ventricular volume was studied in four tests, each including six normal adults. The means of 10 heart cycles of the R-wave amplitude in surface ECG lead V5 (RV5) and the echocardiographically determined left ventricular enddiastolic dimension (LVEDD) were compared before and during different interventions. After inhalation of 0.3 ml isoamylnitrit, LVEDD was reduced to 7.7%, RV5 to 15.0% below control. During a maneuver of Valsalva, LVEDD decreased to 8.6%, RV5 to 12.9% below control. In both tests heart rates increased markedly. After oral application of propranolol (0.7 to 1.0 mg/kg) LVEDD did not change, whereas RV5 decreased to 8.2% below control. During rapid intravenous infusion of 1 l NaCl 0.9% in 10 to 15 minutes, LVEDD increased to 15.7% above control. R-wave amplitude remained constant. Thus the results of these last two tests let us doubt whether the Brody-effect can be translated without limitation on the in-vivo situation in man.

[ST-segment depression and R-amplitude changes during bicycle stress test in patients with coronary artery disease (author's transl)]

56 patients were examined with bicycle stress tests. Sensitivity and specificity of ST-segment depression were compared with R-wave amplitude changes. All patients had a coronary angiography because of suspected coronary artery disease (CAD). The specificity of ST-segment depression was 71%, for R-wave amplitude changes 50%. The sensitivity for ST-segment depression was 76% and for R-wave amplitude changes 50%. In addition in 7 patients with angiographically demonstrated CAD repeated stress tests were done. The ST-segment changes were nearly constant in all examinations, whereas the R-wave amplitude in V5 in 5 out of 7 patients changed considerably between decrease and increase. Considering these intraindividual changes, it seems doubtful whether the evaluation of the R-wave amplitude proves to be an improvement of the non-invasive diagnostic procedures of CAD.

[Captopril in the treatment of essential hypertension (author's transl)]

The antihypertensive effect of captopril was tested on 19 patients with essential hypertension, WHO grade I or II. In 11 patients blood pressure levels returned to normal over an observation period of 12 weeks at a dose of 3 C 50-150 mg daily (group A). In eight patients with grade II hypertension the absolute blood-pressure reduction was the same, but did not reach normal levels (group B). Although additional intake of propranolol, at a dose of 3 X 40 mg daily, achieved further reduction, normal pressures were still not attained. Initial blood pressure levels were higher and plasma-renin activity lower in patients of group B than of group A. There was a definite rise in plasma-renin activity with captopril, but corresponding to the suppression of plasma-renin in severe hypertension it was less. There was a fall in plasma-aldosterone levels, corresponding to a reduced angiotensin II level as a result of inhibition of the converting enzyme. The fall in plasma-aldosterone activity was less in severe hypertension, although there was the same inhibition of converting enzyme activity in both groups. Normochromic anaemia was noted in three patients, requiring further observation and explanation. No patient developed orthostatic hypotension or reflex tachycardia.

[Treatment of essential hypertension with a combination of propranolol, spironolactone-thiabutazide and dihydralazine (author's transl)]

In 61 out-patients with essential hypertension, grade I or II, propranolol was administered alone in increasing doses (3 x 40 mg/d or 3 x 80 mg/d) or, if there was insufficient response, with a double or triple combination consisting additionally of spironolactone (50 mg/d)-thiabutazide (5 mg/d) and dihydralazine (3 x 25 mg/d). This treatment schedule achieved normal pressures in 51 patients, in 22 on 40 mg, in 7 on 80 mg propranolol, in 16 after the addition of the diuretic, and in 6 with the triple combination. Four patients had to be excluded from the study because they developed either marked bradycardia or anxiety states or paraesthesias after propranolol (3 x 40 mg/d). On chronic beta-adrenergic blockade the serum potassium level increased slightly, but remained within normal limits. The initial value of plasma-renin activity was highest in the group of those who responded to the propranolol treatment.