The more physically active you are, the less your blood pressure rises in response to a high-salt diet, researchers reported at the American Heart Association’s Nutrition, Physical Activity and Metabolism/Cardiovascular Disease Epidemiology and Prevention 2011 Scientific Sessions.

“Patients should be advised to increase their physical activity and eat less sodium,” said Casey M. Rebholz, M.P.H., lead author of the study and a medical student at the Tulane School of Medicine and doctoral student at the Tulane University School of Public Health & Tropical Medicine in New Orleans. “Restricting sodium is particularly important in lowering blood pressure among more sedentary people.”

Investigators compared study participants’ blood pressure on two one-week diets, one low in sodium (3,000 mg/day) and the other high in sodium (18,000 mg/day).

The American Heart Association recommends consuming less than 1,500 mg/day of sodium.

If a person’s average systolic blood pressure (the top number in the reading, measured when the heart is contracting) increased 5 percent or more from the low-sodium to the high-sodium regimen, the researchers labeled them as high salt-sensitive.

Based on physical activity questionnaires, researchers divided participants into four groups ranging from very active to quite sedentary.

The average increases in systolic blood pressure after switching from low to high sodium, adjusted for age and gender, were:

• 5.27 mm Hg in the least active group
• 5.07 mm Hg in the next-to-lowest activity group
• 4.93 mm Hg in the next to highest activity group
• 3.88 mm Hg in the most active group

Compared with the sedentary group, the odds of being salt-sensitive, adjusted for age and gender, fell:

• 10 percent in the next-to-lowest activity group
• 17 percent in the next-to-highest activity group
• 38 percent in the most active group

“In all the analyses we found a dose-response relationship with the more activity, the better,” Rebholz said.

The participants were 1,906 Han Chinese adults (average age 38) in the Genetic Epidemiology Network of Salt Sensitivity (GenSalt), a large project to identify genetic and environmental factors contributing to salt sensitivity. Siblings and their parents were invited to become involved in GenSalt if at least one sibling had pre-hypertension (blood pressure between 120/80 and 139/89 mm Hg) or stage-1 hypertension (between 140/90 and 159/99 mm Hg). No one was on blood pressure medication during the study.

The GenSalt project is located in rural China because the homogeneous population makes it more likely that genes influential to blood pressure control will be identified.

“The study needs to be repeated, but I suspect that the relationship between physical activity and salt-sensitivity will apply to other populations,” Rebholz said.

Co-authors are: Dongfeng Gu, Ph.D.; Jing Chen, M.D., M.S.; Jian-feng Huang, M.D.; Jie Cao, M.D., M.S.; Ji-chun Chen, M.D., M.S.; Jianxin Li, M.D.; Fanghong Lu, M.D.; Jianjun Mu, M.D.; Jixiang Ma, M.D.; Dongsheng Hu, M.D., M.S.; Xu Ji, M.D.; Lydia A. Bazzano, M.D., Ph.D.; Depei Liu, M.D., Ph.D.; and Jiang He, M.D., Ph.D.

Author disclosures and sources of funding are on the abstract.

Note: Actual presentation time is 5 p.m ET, Wednesday, March 23, 2011. Statements and conclusions of study authors that are presented at American Heart Association scientific meetings are solely those of the study authors and do not necessarily reflect the association’s policy or position. The association makes no representation or guarantee as to their accuracy or reliability. The association receives funding primarily from individuals; foundations and corporations (including pharmaceutical, device manufacturers and other companies) also make donations and fund specific association programs and events. The association has strict policies to prevent these relationships from influencing science content. Revenues from pharmaceutical and device corporations are available at www.americanheart.org/corporatefunding.

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Previous research has established that calcium supports bone formation and repair, while vitamin D helps the body absorb calcium.  Many experts have suggested the combination of vitamin D and calcium supplementation to reduce the risk of bone fracture among older people, particularly those at risk of or suffering from osteoporosis. M. Karkkainen, from the University of Kuopio (Finland), and colleagues analyzed data collected from participants in the Osteoporosis Risk Factor and Prevention-Fracture Prevention Study (OSTPRE-FPS), involving 3,432 women, ages 66 to 71 years.  A subset of 593 women were randomly selected for bone mineral density (BMD) measurements, with half of the women receiving the daily vitamin D plus calcium supplements, while the other group received nothing.  After three years of study, the researchers report that the total body BMD increased by 0.84% in the intervention group, compared with 0.19% increase in the control group.  Further, the team found that those women who complied the best with the supplementation protocol, taking at least 80% of the supplements, experienced the greatest benefits in BMD measurements.  The researchers conclude that: “Daily vitamin D and calcium supplementation have a positive effect on the skeleton in ambulatory postmenopausal women with adequate nutritional calcium intake. “

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Studies have suggested a role of black raspberries, by way of the polyphenolic compounds they contain, in reducing the risk of a variety of cancers. Wancai Yang, from the University of Illinois at Chicago (Illinois, USA), and colleagues examined the potential activity of black raspberries in the colorectal tract of two mouse models of colorectal cancer. The first strain – Apc1638 – is engineered to develop intestinal tumors, whereas the second strain – Muc2 – induces colitis, an  inflammation of the large intestine that is suspected to contribute to the development of colorectal cancer.  Both sets of mice ate a Western-style diet, high in fat and low in vitamin D and calcium, or the same diet with an additional 10% freeze-dried black raspberry powder.  After 12 weeks, the researchers found that Apc1638 mice that ate the additional raspberries displayed a 45% reduction in tumor incidence and a 60% reduction in the number of tumors. As well, the Muc2 mice fed the additional raspberries showed a reduction in chronic inflammation, with a 50% reduction in both tumor incidence and the number of tumors.  The team concludes that: “Collectively, our data suggest that [black raspberries] are highly effective in preventing intestinal tumor development … through targeting multiple signaling pathways.”

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Purple Pain A new bandage developed by German scientists changes color to indicate infection.Fraunhofer Labs via Gizmag

Researchers in Germany have created bandages that turn purple at the first sign of infection.

A new wound dressing, developed at the Fraunhofer Research Institution for Modular Solid State Technologies EMFT in Munich, includes a special dye that reacts to different pH values.

The new trauma bandage insulates wounds just like any other bandage, but it provides a special window into how a wound is healing. Typically, healthy skin and healed wounds have a slightly acidic pH, around 5 or 6. If this value increases into the alkaline range, that can indicate infection, reports Gizmag.

If the pH value is between 6.5 and 8.5, the new bandage will turn purple, according to Dr. Sabine Trupp, a scientist at the EMFT. The indicator strip can allow patients and doctors to monitor for infection without having to change dressings. This is an advantage because removing a bandage can let in germs. The next step is to test the strips at a German hospital’s dermatology clinic.

Eventually, the researchers want to integrate an optical sensor, which could measure pH values and indicate the results on a screen, providing precise data about whether a wound is getting better.

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Fiber has been suggested by previous studies to be of value in reducing the risk of cardiovascular disease by lowering cholesterol and improving glucose tolerance.  Barley is a food rich in beta glucans, a type of soluble fiber.   Nancy Ames, from the Cereal Research Centre at Agriculture and Agri-Food Canada, and colleagues completed a meta-analysis of eleven studies, finding that barley and beta-glucan isolated from barley significantly lowered both total and low-density lipoprotein (LDL) cholesterol concentrations. Observing that beta-glucan has unique characteristics relating to solubility and molecular weight, which may help it to confer its cholesterol-lowering properties, the team concludes that: “Increased consumption of barely products should be considered as a dietary approach to reduce LDL cholesterol concentrations.”

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Falls are responsible for 90% or more of all hip fractures, which are injuries that are associated with high mortality rates.  Raija Korpelainen, from Oulu Deaconess Institute (Finland), and colleagues followed 160 women who participated in a trial aimed at reducing risk factors for fractures in elderly women with osteopenia (a reduction in bone mass, or low levels of bone calcium):  84 women were assigned to an exercise group, while the remaining 76 women served as controls.  Women in the exercise group attended supervised balance, leg strength and impact training sessions once a week for a 6-month period annually or 4 years.  During the 7.1 year follow-up period, 17 women in the exercise group were hospital-treated for fractures, while 23 fractures occurred in the control group. Additionally, the total incidence rate of fractures in the exercise group was 0.05 per 1,000 women per year versus 0.08 in the control group. The authors found that: “Fractures were proximal in 52.2 percent of the control group and 17.6 percent of the exercise group. Moderate lifelong physical activity decreased the overall risk of having any fractures during the total follow-up period.” Additionally, no hip fractures occurred in the exercise group during the follow-up period, while five hip fractures occurred in the control group.  The researchers also report that the exercise group also “demonstrated a significant gain compared with the control group in mean leg strength during the trial.”  The researchers report that:  “30 months of supervised, mainly home-based exercises followed by voluntary home training had a positive long-term effect on balance and gait in high-risk elderly women,” and that “life-long physical activity was associated with reduced risk of fractures.”

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A team of Japanese scientists may have discovered an ideal source of induced-pluripotent stem cells (iPS), a non-embryonic source of stem cells for future regenerative medical applications.  Hajime Ohgushi, from the National Institute of Advanced Industrial Science and Technology (Japan), and colleagues find that third molars, commonly known as wisdom teeth, are a rich source of mesenchymal stromal cells that are similar to cells found in bone marrow, a common stem-cell source. Collecting tooth samples from three donors, the team successfully generated a series of iPS cell lines by activating three key genes; the different cell lines displayed varying degrees of robustness but in some cases proliferated quite well, up to 100 times more efficiently than typical skin-cell-derived iPS cells. The molar-derived cells also could differentiate into many other cell types including beating cardiomyocytes (heart cells).  Noting that: “Because human third molars are discarded as clinical waste,” the researchers submit that: “our data indicate that clonally expanded [mesenchymal stromal cells] derived from human third molars are a valuable cell source for the generation of [induced-pluripotent stem] cells.”

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Among the most frequently consumed beverages worldwide, coffee is rich in antioxidants, with one cup providing 350 mg of phenolic compounds.  A team of researchers from the University of Vienna (Austria), the University of Belgrade (Serbia), and other European institutions enrolled 38 men and women for a controlled intervention trial with a cross-over design. Each subject consumed 800 ml of paper-filtered coffee or water daily over 5 days. The researchers found that coffee reduced the oxidative damage to DNA, as measured by a decreased formation of oxidized purines, by 12.3%. No significant changes in levels of antioxidants in the blood, or levels of reactive oxygen species in the blood, were observed.  The team concludes that: “Overall, the results indicate that coffee consumption prevents endogenous formation of oxidative DNA-damage in human, this observation may be causally related to beneficial health effects of coffee seen in earlier studies.”

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New research suggests that hand drying technique could be as important as hand washing technique.  Researchers at the University of Bradford in the UK investigated different methods of hand drying and their effect on transfer of bacteria from the hands to other surfaces. The methods investigated were paper towels, traditional hand dryers, which dry hands by evaporation, and a new type of hand dryer, which uses high velocity air to strip water off the hands. Volunteers were asked to wash their hands and place them onto contact plates which were then incubated to measure bacterial growth. The volunteers were then asked to dry their hands using either hand towels or one of three hand dryers, with or without rubbing their hands together, and levels of bacteria were re-measured. Results showed that rubbing the hands together while drying the hands could counteract the benefits of hand washing as bacteria present within the skin can be brought to the surface and then transferred to other surfaces, along with surface bacteria that were not removed by washing the hands. The most efficacious method at keeping bacterial counts low was paper towels. Study leader Dr Snelling concluded:  “Good hand hygiene should include drying hands thoroughly and not just washing. The most hygienic method of drying hands is using paper towels or using a hand dryer which doesn’t require rubbing your hands together.”

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The default mode network (DMN) is a brain circuit which dominates brain activity when a person is least engaged with the outside world (such as being a passive observer).  Previous studies have found that a loss of coordination in the DMN is a common symptom of aging and in extreme cases can be a marker of disease, and data has suggested that older adults who are more fit tend to have better connectivity in specific regions of the DMN than their sedentary peers. Arthur Kramer, from the University of Illinois (Illinois, USA), and colleagues followed 65 adults, ages 59 to 80 years, who were sedentary (two or fewer episodes of physical activity lasting 30 minutes or more in the previous six months), who joined a walking group or stretching and toning group for a year. The researchers measured participants’ brain connectivity and performance on cognitive tasks at the beginning of the study, at six months and after a year of either walking or toning and stretching. The team employed functional magnetic resonance imaging (fMRI) to determine whether aerobic activity increased connectivity in the DMN or other brain networks.  At the end of the year, DMN connectivity was significantly improved in the brains of the older walkers, but not in the stretching and toning group. Additionally, the walkers also had increased connectivity in parts of the fronto-executive network, which aids in the performance of complex tasks; and they performed significantly better on cognitive tests than their toning and stretching peers. The researchers write that: “The study provides the first evidence for exercise-induced functional plasticity in large-scale brain systems in the aging brain …  and offers new insight into the role of aerobic fitness in attenuating age-related brain dysfunction.”

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