Thursday, June 30, 2011

Using gene therapy to prevent heart failure

ScienceDaily (Nov. 15, 2010) — A Nova Southeastern University (NSU) researcher has discovered how to use gene therapy to block a protein that can contribute to heart failure. The finding will appear in an upcoming issue of the Journal of the American College of Cardiology.

Anastasios Lymperopoulos, Ph.D., an NSU College of Pharmacy assistant professor of pharmacology, has discovered a novel method, using gene therapy, to block the actions of a gene-encoded protein known as beta-arrestin 1, which causes an increase of aldosterone production from the body's adrenal glands into the blood. Aldosterone is a hormone. It increases the reabsorption of sodium and water into the kidneys, causing high blood volume and blood pressure. It also has several direct damaging effects on the heart, such as fibrosis, hypertrophy, and inflammation.

An increase in blood volume causes high blood pressure. This in turn decreases the pumping action of the heart, and is one of the causes of heart failure.

By finding a way to block beta-arrestin 1 through this gene therapy approach, Prof. Lymperopoulos hopes it will lead to the reduction of the severity of heart failure. He is now testing new and existing heart failure medications such as Cozaar, Diovan and Atacand, to see how effective they are at blocking this damaging effect of beta-arrestin on the heart.

Lymperopoulos receives funding from the American Heart Association through a Scientist Development Grant for his research at NSU.

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The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Nova Southeastern University, via EurekAlert!, a service of AAAS.

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Bioactive compounds in berries can reduce high blood pressure

ScienceDaily (Jan. 15, 2011) — Eating blueberries can guard against high blood pressure, according to new research by the University of East Anglia (UEA) and Harvard University.

High blood pressure -- or hypertension -- is one of the major cardiovascular diseases worldwide. It leads to stroke and heart disease and costs more than $300 billion each year. Around a quarter of the adult population is affected globally -- including 10 million people in the UK and one in three US adults.

Published next month in the American Journal of Clinical Nutrition, the new findings show that bioactive compounds in blueberries called anthocyanins offer protection against hypertension. Compared with those who do not eat blueberries, those eating at least one serving a week reduce their risk of developing the condition by 10 per cent.

Anthocyanins belong to the bioactive family of compounds called flavonoids and are found in high amounts in blackcurrants, raspberries, aubergines, blood orange juice and blueberries. Other flavonoids are found in many fruits, vegetables, grains and herbs. The flavonoids present in tea, fruit juice, red wine and dark chocolate are already known to reduce the risk of cardiovascular disease.

This is the first large study to investigate the effect of different flavonoids on hypertension.

The team of UEA and Harvard scientists studied 134,000 women and 47,000 men from the Harvard established cohorts, the Nurses' Health Study and the Health Professionals Follow-up Study over a period of 14 years. None of the participants had hypertension at the start of the study. Subjects were asked to complete health questionnaires every two years and their dietary intake was assessed every four years. Incidence of newly diagnosed hypertension during the 14-year period was then related to consumption of various different flavonoids.

During the study, 35,000 participants developed hypertension. Dietary information identified tea as the main contributor of flavonoids, with apples, orange juice, blueberries, red wine, and strawberries also providing important amounts. When the researchers looked at the relation between individual subclasses of flavonoids and hypertension, they found that participants consuming the highest amounts of anthocyanins (found mainly in blueberries and strawberries in this US-based population) were eight per cent less likely to be diagnosed with hypertension than those consuming the lowest amounts. The effect was even stronger in participants under 60.

The effect was stronger for blueberry rather than strawberry consumption. Compared to people who ate no blueberries, those eating at least one serving of blueberries per week were 10 per cent less likely to become hypertensive.

"Our findings are exciting and suggest that an achievable dietary intake of anthocyanins may contribute to the prevention of hypertension," said lead author Prof Aedin Cassidy of the Department of Nutrition at UEA's Medical School.

"Anthocyanins are readily incorporated into the diet as they are present in many commonly consumed foods. Blueberries were the richest source in this particular study as they are frequently consumed in the US. Other rich sources of anthocyanins in the UK include blackcurrants, blood oranges, aubergines and raspberries."

The next stage of the research will be to conduct randomised controlled trials with different dietary sources of anthocyanins to define the optimal dose and sources for hypertension prevention. This will enable the development of targeted public health recommendations on how to reduce blood pressure.

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The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by University of East Anglia.

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Wednesday, June 29, 2011

Benefit of exercise in patients with hypertension has been insufficiently investigated, experts say

ScienceDaily (Oct. 26, 2010) — There are many good reasons to ensure sufficient exercise in everyday life. However, advising patients with increased blood pressure (hypertension) to exercise regularly is often regarded as a specific medical measure aiming to reduce the increased risk of late complications. But whether more exercise actually helps to avoid illnesses related to hypertension or at least delay their onset has been insufficiently investigated. In order to provide better advice to patients with hypertension, informative clinical studies are therefore needed.

This is the result of a report published by the German Institute for Quality and Efficiency and Health Care (IQWiG) on Sept. 22, 2010.

Comprehensive commission package on hypertension

This report is part of a comprehensive commission package awarded by the Federal Joint Committee (G-BA) in which the benefit of various non-drug treatment strategies for essential hypertension was to be assessed. This is the most common type of hypertension, for which no clear cause can be found.

People with increased blood pressure receive much well-meant advice, for example, to adopt stress-management strategies, smoke less and drink less alcohol. These measures are also recommended in clinical practice guidelines. IQWiG has already completed reports on the questions as to how a reduction in weight and salt intake affect blood pressure.

What should "more exercise" achieve?

Patients with hypertension have an increased risk of certain diseases of the heart and circulatory system. Strokes, heart attacks and also kidney failure are more common in people with hypertension than in those without this disorder.

The researchers at IQWiG were therefore particularly interested firstly, to know whether people with hypertension, by exercising more, can actually reduce the risk of heart attacks or stroke, for example, and secondly, to determine how more exercise affects their health-related quality of life.

Studies included only a few participants

The researchers searched for studies in which volunteers with hypertension had been randomly assigned to two groups. Patients in the intervention group had been advised to exercise more over a longer period of time (e.g. cycling, running, hiking, swimming), while those in the control group had not been given this advice. In addition, only studies lasting 24 weeks or more were considered.

Overall, IQWiG and its external experts included 8 randomized controlled trials lasting 6 to 12 months in the assessment. The studies were relatively small; most included a maximum of 20 people per study group. In addition, most studies were prone to bias, which greatly limited their informative value.

Side effects not investigated

As the assessment showed, the studies considered in the report allow no conclusions on patient-relevant aspects of the benefit of increased physical activity in hypertension. The studies did not provide sufficient results, neither on mortality, disease of the heart and circulatory system (cardiovascular morbidity), and kidney failure (end-stage renal disease), nor on health-related quality of life. Sufficient data were also lacking on side effects (adverse events): as many elderly patients suffer from hypertension they could potentially have a higher risk of falling or injuring themselves.

Systolic blood pressure lowered

In contrast, in all studies the effects of exercise on blood pressure were analysed. The data show that increased physical activity could lower the systolic (higher) value by 5 to 8 mmHg. In contrast, no differences between treatment groups were shown for the diastolic (lower) value. However, the researchers cannot safely predict whether the reduction in the systolic value is long term and what the effects on health are. A reduction in blood pressure is an indication that the risk of late complications may be diminished. However, it is well-known with regard to drugs that even if medications are similarly effective in reducing blood pressure, they may still fail to prevent late complications such as heart damage equally well, and also produce different side effects.

In addition, it could not be concluded from the studies whether participants could reduce the intake of blood-pressure lowering medications through exercising more often.

Advice on lifestyle changes also investigated in studies

"To avoid misunderstandings: our conclusion is not that more exercise is useless or even harmful," says Professor Dr. med. Jürgen Windeler, IQWiG's Director. "However, it is a sobering fact that medications to lower blood pressure have been tested in dozens of large studies but we still know little about the advantages and disadvantages of physical activity, even though national and international professional associations have recommended this measure for a long time." This imbalance should be corrected. "Advising patients with hypertension to exercise more will often mean a substantial change in their life style; patients should know whether they benefit from this."

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The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Institute for Quality and Efficiency in Health Care, via EurekAlert!, a service of AAAS.

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Tuesday, June 28, 2011

Lead exposure may affect blood pressure during pregnancy

ScienceDaily (Feb. 6, 2011) — Even minute amounts of lead may take a toll on pregnant women, according to a study published by Lynn Goldman, M.D., M.S., M.P.H., Dean of George Washington University's School of Public Health and Health Services in D.C., and colleagues, in the journal Environmental Health Perspectives. Although the levels of lead in the women's blood remained far below thresholds set by the Centers for Disease Control and Prevention (CDC) and standards set by the Occupational Safety and Health Administration, women carrying more lead had significantly higher blood pressure.

"We didn't expect to see effects at such low levels of lead exposure," says Goldman, "but in fact we found a strong effect." If confirmed, this would indicate that pregnant women may be as sensitive to lead toxicity as young children.

Blood pressure is slightly higher during pregnancy, child labor, and delivery as the heart pumps harder. But prolonged high blood pressure during pregnancy (pregnancy-induced hypertension) can lead to complications called preeclampsia and then eclampsia. This potentially lethal condition also can predispose women to a heart attack in their future. While any increase in blood pressure during pregnancy is worrisome, the study did not find an association between lead and pregnancy-induced hypertension or preeclampsia.

The CDC advises to take action to reduce exposures when pregnant women or children have a blood lead level of 5 micrograms (ug) per deciliter (dL) or higher. However, very few studies have assessed the effect of lower levels of lead in pregnant women. Goldman feels that the recent study suggests that there are cardiovascular effects of lead in pregnant women at levels well below 5 ug/dL.

Of the 285 pregnant women monitored by the team at Johns Hopkins Hospital in Baltimore, Maryland, about 25% had a lead level higher than about 1 ug/dL of umbilical cord blood; it was these women who on average had a 6.9 mmHg increase in systolic pressure and a 4.4 mmHg increase in diastolic pressure. To arrive at these results, the team statistically controlled for other factors related to raised blood pressure, including ethnicity, obesity, anemia, household income and smoking.

"Hopefully our study will contribute to efforts to determine what a safe level of lead is for adults," said Ellen Wells, PhD, first author of the study and postdoctoral scholar at Case Western Reserve University School of Medicine in the Department of Environmental Health Sciences. The best way to reduce lead in women's blood is to prevent exposure, not only during but also prior to pregnancy. "Because lead is stored in bones for many years," Wells says, "even childhood exposure could impact lead levels in pregnancy."

Limiting levels of lead permitted in adults at the workplace might be a good place to start. "The occupational standard right now is a level of 40 um/dL," says Goldman, "and we see blood pressure changes at a level of 2."

Her words come at a pivotal time. On December 17, President Obama was asked to sign a bill into law that would reduce exposure to lead by tightening restrictions on lead in drinking water plumbing. The bill follows a series of investigations finding significant levels of lead in water in schools and in households in New York City and Washington, D.C. Although lead exposure has steadily declined in the U.S. since the nineties, primarily because of bans on lead in gasoline and drinking water regulations, this study suggests lead restrictions should remain a public health priority.

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by George Washington University.

Journal Reference:

Ellen M. Wells, Ana Navas-Acien, Julie B. Herbstman, Benjamin J. Apelberg, Ellen K. Silbergeld, Kathleen L. Caldwell, Robert L. Jones, Rolf U. Halden, Frank R. Witter, Lynn R. Goldman. Low Level Lead Exposure and Elevations in Blood Pressure During Pregnancy. Environmental Health Perspectives, 2011; DOI: 10.1289/ehp.1002666

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Monday, June 27, 2011

Adherence course reduces hypertension

ScienceDaily (Feb. 16, 2011) — A high proportion of patients with high blood pressure are failing to take their medication properly and would benefit clinically from a course of 'adherence therapy', according to new research from the University of East Anglia (UEA).

High blood pressure -- or hypertension -- is one of the major cardiovascular diseases worldwide. It leads to stroke and heart disease and costs more than $300 billion each year. Around a quarter of the adult population is affected -- including 10 million people in the UK.

Around half of patients with hypertension fail to reduce their blood pressure because they are not taking their prescribed medication correctly. Some cease taking their medication altogether, others only take some of it, and others do not follow the instructions to take their medicine after food, for example.

The reasons for this non-adherence are complex and include ambivalence about taking drugs, concerns over side effects, and complexity of treatment regimes. Previous attempts to improve adherence with information leaflets, monthly outpatient visits, reminders and self-monitoring have been shown to be mostly ineffective.

The UEA resesarchers studied 136 patients with high blood pressure in three outpatient clinics in Jordan. Half were given a course of seven weekly 'adherence therapy' sessions and half continued with their usual treatment. The 20-minute face-to-face sessions allowed a trained clinician to provide tailored information about the illness and treatment, and explore the patient's individual beliefs, fears and lifestyle.

Published February 16 in the Journal of Human Hypertension, the results show that the patients given adherence therapy took 97 per cent of their medications (compared with only 71 per cent for those given treatment as usual) and, on average, reduced their blood pressure by around 14 per cent -- taking it to just above the healthy range.

Lead author Prof Richard Gray of UEA's School of Nursing and Midwifery said: "Our findings suggest a clear clinical benefit in these patient-centred sessions.

"High blood pressure affects millions of people in both the developed and developing world and the problem is likely to increase dramatically over the next 15 years. Tackling the widespread failure to take medication correctly would lead to a major reduction in stroke and heart disease.

"If adherence therapy were a new drug it would be hailed as a potentially major advance in hypertension treatment."

Adherence therapy was originally developed by Prof Gray for patients with mental health problems who failed to take their medication correctly. The total cost of delivering a course of seven weekly sessions is calculated to be approximately £80 per person. Although the UEA study was not designed to formally evaluate cost effectiveness, other studies predict that a long-term reduction of blood pressure would lead to a reduction in stroke of 56 per cent and a reduction in chronic heart disease of 37 per cent -- suggesting that adherence therapy would likely be a cost-effective intervention.

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The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by University of East Anglia, via EurekAlert!, a service of AAAS.

Journal Reference:

Fadwa Allalaiqa, Katherine Deane, Ahmed Nawafleh, Allan Clark and Richard Gray. Adherence therapy for medication non-compliant patients with hypertension: a randomised controlled trial. Journal of Human Hypertension, February 17 2011

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Consumption of 'good salt' can reduce population blood pressure levels, research finds

ScienceDaily (Sep. 15, 2010) — An increased intake of 'good' potassium salts could contribute significantly to improving blood pressure at the population level, according to new research. The favourable effect brought about by potassium is even estimated to be comparable with the blood pressure reduction achievable by halving the intake of 'bad' sodium salts (mostly from table salt).

Those are the conclusions drawn by Linda van Mierlo and her colleagues at Wageningen University, part of Wageningen UR, and Unilever in their investigation of the consumption of potassium in 21 countries. An article describing their findings appears in the journal Archives of Internal Medicine.

The risk of developing cardiovascular diseases rises as blood pressure increases. In Western countries only 20-30% of the population has 'optimal' blood pressure, with the systolic (maximum) pressure being lower than 120 mm Hg and the diastolic (minimum) pressure lower than 80 mm Hg. Blood pressure increases with age in most people. Men more often have a higher blood pressure than women.

Diet and lifestyle plays an important role in managing blood pressure. High intakes of sodium and low intakes of potassium have unfavorable effects on blood pressure. Therefore, reducing the consumption of sodium and increasing the consumption of potassium are both good ways to improve blood pressure.

The study carried out by food researchers from the Human Nutrition department at Wageningen University and from the Nutrition & Health department at Unilever demonstrates that the average potassium intake in 21 countries including the US, China, New Zealand, Germany and the Netherlands varies between 1.7 and 3.7 g a day. This is considerably lower than the 4.7 g a day, which has been recommended based on the positive health effects observed at this level of intake.

A hypothetical increase in the potassium intake to the recommended level would reduce the systolic blood pressure in the populations of these countries by between 1.7 and 3.2 mm Hg. This corresponds with the reduction that would occur if Western consumers were to take in 4 g of salt less per day. The intakes of both potassium and sodium are therefore of importance in preventing high blood pressure.

Earlier studies have shown that salt reduction of 3 g per day in food could reduce blood pressure and prevent 2500 deaths per year due to cardiovascular diseases in the Netherlands. In Western countries, salt consumption can be as high as 9-12 g a day whereas 5 g is the recommended amount according to WHO standards. Most household salt is to be found in processed foods such as bread, ready-made meals, soups, sauces and savoury snacks and pizzas. An effective way of increasing potassium intake is to follow the guidelines for healthy nutrition more closely, including a higher consumption of vegetables and fruit. In addition, the use of mineral salts in processed foods -- by which sodium is partly replaced by potassium -- would contribute to an improved intake of both sodium and potassium.

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The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Wageningen University and Research Centre, via AlphaGalileo.

Journal Reference:

Linda A. J. van Mierlo; Arno Greyling; Peter L. Zock; Frans J. Kok; Johanna M. Geleijnse. Suboptimal Potassium Intake and Potential Impact on Population Blood Pressure. Archives of Internal Medicine, 2010; 170 (16): 1501-1502 DOI: 10.1001/archinternmed.2010.284

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Sunday, June 26, 2011

Small BMI change in overweight children could have big blood pressure impact

ScienceDaily (Oct. 15, 2010) — Small changes in weight can make bigger differences in the blood pressure for overweight children, compared to those at normal weight, according to a new study.

Researchers tracked blood pressure, height and weight of 1,113 children over time, with the longest follow-up exceeding 10 years. They then compared the children's body mass index (BMI, a measure of body weight) to national charts adjusted for age, sex and height. Kids with BMIs in the 85th percentile or higher are considered overweight.

"Below the 85th percentile, BMI effects on blood pressure appear to be fairly linear," said Wanzhu Tu, co-author of the study. "After the 85th, particularly after the 90th percentile, the BMI effect became noticeably stronger."

Analysis indicated the effect on systolic blood pressure of overweight boys' BMI percentile was 4.6 times that in normal-weight boys. Systolic blood pressure is a measure of the force of the blood pumped by the heart against the arteries when the heart is contracted. Findings were similar for diastolic pressure in boys, and both readings in girls. Diastolic blood pressure is a measure of the force of the blood against the arteries when the heart is relaxed and is the top number in a blood pressure reading.

In normal-weight children, BMI percentile and blood pressure remained related but the associations were weaker.

BMI and blood pressure studies typically don't separate normal-weight and overweight children, so findings tend to overestimate BMI's effect on blood pressure in normal-weight children but underestimate it in overweight kids, Tu said.

"Because our estimate of the BMI effect was much greater in overweight kids, the results suggest that even a modest reduction in BMI may produce a much greater benefit in blood pressure in overweight kids," Tu said. "Conversely, a small increase in BMI could put them at much greater risk of blood pressure elevation."

The paper was presented October 15 at the American Heart Association's High Blood Pressure Research 2010 Scientific Sessions (HBPR 2010) held in Washington, DC, USA.

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The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by American Heart Association, via EurekAlert!, a service of AAAS.

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