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LE Magazine October 2002
Studies
from throughout the world that can help you live
longer
October 2002 Table of
Contents
1. Periodontal disease and elevated
cholesterol
Periodontitis is associated with increased prevalence of
cardiovascular morbidity and mortality. It is thought that the
presence of periodontal pockets, which can harbor pathogenic
microorganisms and cause an immune response, could elicit a
systemic effect. Therefore, a study examined if periodontal
pockets may be associated with elevated blood lipid levels, a
known risk factor for atherosclerotic disease. The periodontal
health of 10,590 Israeli military service men and women was
assessed using the Community Periodontal Index of Treatment
Needs (CPITN). The relationship of blood lipids and
periodontal disease and CPITN index was tested, controlling
for factors that are related to elevated cholesterol levels,
including high body mass index (BMI), age, diastolic blood
pressure and smoking. The results showed that the presence of
periodontal pockets was positively associated with higher
cholesterol and LDL cholesterol blood levels in men. No
significant association was found in women. The findings
support the reports linking increased prevalence of
cardiovascular mortality among those with periodontal
disease.
JOURNAL OF PERIODONTOLOGY, 2002, Vol
73, Iss 5, pp 494-500
2. Cognitive
performance and death in the oldest old
A study examined the cognition-survival relationship among
466 nondemented individuals (age 80 to 98). There were three
examinations at two-year intervals. During the six years of
follow-up, 206 individuals died. Tests of cognitive
functioning encompassed crystallized knowledge, inductive
reasoning, visuospatial ability, short-term memory, episodic
memory and speed. There were significant associations found
between cognitive performance at the start of the study, and
subsequent survival. After adjusting for stroke and indicators
of cardiovascular disease, only three out of six cognitive
areas remained significant predictors of survival. There was
limited evidence for an accelerated decline before death. The
main results suggest that the level of cognitive performance
in late life is associated with proximity to death, and that
this relationship is longstanding, and partially influenced by
compromised functioning of the heart and brain.
JOURNALS OF GERONTOLOGY SERIES
B-PSYCHOLOGICAL SCIENCES AND SOCIAL SCIENCES, 2002, Vol 57,
Iss 3, pp P268-P276
3. Risk and
protection of physical functioning in older adults
The inevitability of declining health in older age may be
exaggerated, including declines for those with chronic health
conditions. Data from the MacArthur Study of Successful Aging
were used to examine the impact of sociodemographic, health
status, health behavior and social and psychological factors
on patterns of change in physical functioning over a 2.5-year
period for groups of older adults with prevalent hypertension,
diabetes, cardiovascular disease (CVD), cancer, or fractures,
and those with no chronic conditions at the start. The results
revealed a consistently protective effect of regular physical
activity with respect to patterns of change in physical
functioning in nearly all groups. For those with CVD, greater
emotional support was associated with higher starting
functioning levels and less declines in functioning. Greater
social conflict was associated with greater decline among
those with high blood pressure or diabetes. For those with a
history of cancer, helpful self-efficacy beliefs were
protective, and lower psychological symptoms was associated
with less risk of decline among those with a history of
fracture. Social and psychological factors were unrelated to
changes in functioning for those with no chronic conditions.
The findings suggest that risks for decline in physical
functioning are influenced by a number of potentially
modifiable factors. These factors could be targets for
intervention and treatment to promote better functioning, even
among older adults with various types of chronic
conditions.
JOURNALS OF GERONTOLOGY SERIES
B-PSYCHOLOGICAL SCIENCES AND SOCIAL SCIENCES, 2002, Vol 57,
Iss 3, pp S135-S144
4. Cardio
respiratory fitness and cancer mortality in men
A study investigated the association between cardio
respiratory fitness and smoking-related, nonsmoking-related,
and total cancer mortality in 25,892 men (age 30 to 87), who
had a preventive medical evaluation, including a maximal
exercise test and self-reported health habits. There were 335
cancer deaths (133 from smoking-related cancer, 202 from
nonsmoking-related cancer) during an average of a 10-year
follow-up. The results showed an opposite association between
cardio respiratory fitness levels and smoking-related,
nonsmoking-related and total cancer mortality. Moderate and
high levels of cardio respiratory fitness were associated with
lower risk of smoking-related and nonsmoking-related cancer
mortality when compared with low fitness in men.
Smoking-related mortality rates were progressively lower
across low, moderate, and high fitness groups in former and
current smokers. They concluded that cardio respiratory
fitness may provide protection against cancer mortality in
men.
MEDICINE AND SCIENCE IN SPORTS AND
EXERCISE, 2002, Vol 34, Iss 5, pp 735-739
5. Physical
activity and stress in women
A study examined the relationship between physical activity
and levels of blood lipid peroxides, superoxide dismutase
(SOD, endogenous antioxidant) in erythrocytes (red blood
cells), and glutathione peroxidase (GSH-Px, endogenous
antioxidant) in whole blood activities of 488 Spanish women.
The study defined two categories of leisure time physical
activity, according to their intensity: 1) Low (less than or
equal to 6 METs (Metabolic Energy Equivalent) and 2) High
(greater than 6 METs). (A MET is the most precise measurement
of metabolic load, and therefore cardiovascular load. Resting
energy expenditure is considered 1 MET. Walking requires 2 to
4.5 METs, and running or bicycling requires 6 METs or more).
The amount of leisure time physical activity was associated
with high activity levels of SOD and GSH-Px. Similar results
were obtained when physical activity in household activities
was added to total leisure physical activity. Physical
activity of low intensity was associated with high SOD levels,
and physical activity of high intensity with high GSH-Px
activity levels. Thus, the amount and intensity of leisure
physical activity were directly related to both antioxidant
enzyme activity levels. The results suggest that leisure
physical activity intensity has a modulatory effect on
antioxidative balance in women.
MEDICINE AND SCIENCE IN SPORTS AND
EXERCISE, 2002, Vol 34, Iss 5, pp 814-819
6. DNA
damage: a predictor of atherosclerosis
Atherosclerosis and the development of cancer may share some
common mechanisms of exogenous compounds that cause disease by
damaging DNA (genotoxic), such as polycyclic aromatic
hydrocarbons (PAHs). A study tested whether DNA-adducts in
muscle cells of the largest artery, the aorta, are associated
with the stage of atherosclerosis. The data was taken at
autopsy from 133 sudden and accidental male deaths, (age 30 to
60). The main group (66) had severe atherosclerotic damage.
The control group had slight and moderate total
atherosclerotic body damage. The results showed significantly
higher DNA-adduct levels in the main group as compared with
the controls (2.11 adducts vs. 1.49). Those in the main group
were significantly older and had elevated heart weight and
blood cholesterol levels, and a higher frequency of being
overweight as compared with the control group. There were no
significant differences in DNA-adduct levels between smokers
and non-smokers within either group. Thus, DNA-adducts, which
are most likely related to environmental exposure to genotoxic
chemicals, remain a statistically significant predictor of the
stage of atherosclerosis. Since DNA-adduct levels predict the
progression of atherosclerosis, independently of smoking, this
indicates that the formation of atherosclerotic plaques may
also be caused by environmental exposures other than tobacco
smoke.
MUTATION RESEARCH-FUNDAMENTAL AND
MOLECULAR MECHANISMS OF MUTAGENESIS, 2002, Vol 501, Iss 1-2,
pp 115-128
7. Effect of
aloe against liver cell toxicity
Aloe is a familiar ingredient in a wide range of health care
and cosmetic products and has been reported to possess various
physiological effects, antioxidative, anticarcinogenic,
anti-inflammatory and laxative. Aloe has been reported to have
an effect on liver function. A study evaluated the
cytoprotective effect of aloe extract against artificially
induced liver toxicity, in cultured rat cells. After exposure
to the liver toxicity inducer, there was a decrease in cell
viability. Cellular glutathione (GSH) and protein-SH levels
were also significantly decreased in a time-dependent manner.
However, the addition of aloe extract resulted in a
dose-dependent improvement of these effects. This
cytoprotective effect of aloe could be attributed to its
inhibition of GSH depletion. The effect of the aloe extracts
were also dose-dependent. The results suggest that toxicity in
liver cells may be inhibited by aloe extract.
PHARMACOLOGY & TOXICOLOGY, 2002,
Vol 90, Iss 5, pp 278-284
8. Cell
phones linked with cell damage
A two-year study in Finland has found that mobile phone
radiation can cause changes in human cells that might affect
the brain. The study found that exposure to radiation from
mobile phones can cause increased activity in hundreds of
proteins in human cells grown in a laboratory. It was not yet
known whether the biological response that was detected could
have any physiological effects on the human brain or body. The
study focused on changes in cells that line blood vessels, and
on whether such changes could weaken the functioning of the
blood-brain barrier which prevents potentially harmful
substances from entering the brain from the blood stream.
Changes in the overall pattern of protein phosphorylation
suggest that mobile phone radiation activates a variety of
cellular signal transduction pathways, among them the hsp27
stress response pathway. They found that the hsp27 protein was
linked to the functioning of the blood-brain barrier and
showed increased activity due to irradiation. (Irradiation did
not alter the temperature of cell cultures, which remained
throughout the irradiation period at 37±0.3°C.)
There is a possibility that such activity could make the
shield more permeable. Increased protein activity might cause
cells to shrink. Then tiny gaps could appear between those
cells through which some molecules could pass. Based on the
known functions of hsp27, researchers hypothesized that mobile
phone radiation-induced activation of hsp27 may facilitate the
development of brain cancer. These events, when occurring
repeatedly over a long period, might become a health hazard
because of the possible accumulation of brain tissue damage.
Their hypothesis suggests that other brain damaging factors
may co-participate in mobile phone radiation-induced effects.
A Swedish group also suggested a possible link with
Alzheimer's disease. The study raises new questions about
whether mobile phone radiation can weaken the brain's
protective shield against harmful substances. More research is
needed to determine the seriousness of the cell changes and
their impact on the brain or the body.
DIFFERENTIATION 2002 May;70
(2-3):120-9
9. Pyruvate
blocks zinc-induced neurotoxicity
Zinc is an essential trace element and present at high
concentrations in the central nervous system. Recent studies
have revealed that excess amount of extracellular zinc is
neurotoxic, and that the disruption of zinc homeostasis may be
related to various neurodegenerative diseases. In a recent
study, zinc (25-100 muM) caused significant death of
immortalized (reproduce indefinitely) neurons in the
hypothalamus of the brain in a dose and time dependent manner.
(The hypothalamus regulates many metabolic processes,
including body temperature and certain emotional states.) The
results showed that pre-administration of sodium pyruvate (1-2
mM), however, inhibited the zinc-induced neurotoxicity.
Carnosine has also been shown to protect against this type of
zinc toxicity to the brain.
CELLULAR AND MOLECULAR NEUROBIOLOGY
2002;22(1):87-93.
10. CRP: an
independent predictor of diabetes
Accumulating evidence implicates inflammation in the
development of type 2 diabetes. Elevated CRP is a known
indicator of inflammation. A study assessed the ability of
C-reactive protein (CRP, a blood protein) to predict the
development of diabetes in 5,245 middle-aged men. During the
study, 127 transitioned from normal glucose control to overt
diabetes. The results showed CRP to be an important predictor
of diabetes development, independent of other predictors,
including starting level, bone BMI, fasting triglycerides and
glucose concentrations. In addition, there was an increase in
risk across CRP measurement groups even after one year. The
highest group (CRP greater than 4.18 mg/l) was associated with
a greater than three-fold risk (3.07) of developing diabetes
at five years. Thus, CRP predicts the development of type 2
diabetes in middle-aged men, independently of established risk
factors. These results have potential in helping to better
predict those destined to develop type 2 diabetes, as well as
adding to the notion that low-grade inflammation is important
in the development of type 2 diabetes.
DIABETES 2002;51(5):1596-1600
11. Vitamin
C prevents DNA mutations
The precise role of vitamin C in the prevention of DNA
mutations is controversial. Although vitamin C has strong
antioxidant properties, it also has pro-oxidant effects in the
presence of free transition metals. Vitamin C was recently
reported to induce the decomposition of lipid hydrogen
peroxides (H2O2), independent of interaction with metals,
suggesting that it may cause DNA damage. To directly address
the role of vitamin C in maintaining the integrity of genes, a
study developed a genetic system for quantifying mutations
induced in human cells under free radical stress. Cells were
loaded with vitamin C by exposing them to dehydroascorbic acid
(the reversibly oxidized form of vitamin C), thereby avoiding
transition metal-related pro-oxidant effects of vitamin C.
Vitamin C loading resulted in substantially decreased
mutations induced by H2O2. Without vitamin C, the depletion of
glutathione led to cell toxicity and an increase in
H2O2-induced mutation frequency. However, in cells preloaded
with vitamin C, glutathione depletion was substantially
decreased, as was a decrease in total 8-oxo-guanine measured
in the DNA of cells. This directly supports the concept that
high intracellular concentrations of vitamin C can prevent
oxidation-induced mutations in human cells.
JOURNAL OF BIOLOGICAL CHEMISTRY
2002;277(19):16895-9
12. Neuroprotective effects of
carnosine
Carnosine, a molecule composed of amino acids, has
demonstrated in numerous animal studies strong and specific
antioxidant properties, protection against radiation damage,
improvement in the function of the heart, and promotion of
wound healing. It is found in high concentration in skeletal
muscle, heart muscle and in the brain, and has been suggested
to provide neuroprotection. A study exposed cell cultures to
oxygen-glucose-deprivation (OGD) followed by reoxygenation
(after 18 hours) under regular atmospheric oxygen level. The
toxicity induced was partially caused by generation of free
radicals. It was found that 5 mM carnosine provided maximal
neuroprotection of about 50% against OGD trauma. This
neuroprotective effect was similar to that of a known
antioxidant drug and free radial scavenger, tempol. This
indicates that carnosine may act as an
antioxidant-neuroprotective agent in the brain.
JOURNAL OF NEUROSCIENCE RESEARCH
2002;68(4):463
13. Supplemental glutathione and diabetic
nephropathy
Recently, much attention has focused on the role of free
radical stress in the various forms of tissue damage in those
with diabetes. A study examined the involvement of free
radicals in the progression of kidney dysfunction and
neuropathy in diabetes, and evaluated the potential usefulness
of glutathione (GSH) in diabetes. Diabetic rats were treated
with 1 g/100 g GSH as a dietary supplement. GSH significantly
suppressed the diabetes-induced increase in urinary
8-hydroxy-2'-deoxyguanosine (indicator of free radical
stress). It also prevented the diabetes-induced increases in
albumin and creatinine in urine. The dietary GSH also
normalized the rats' tail flick reaction time to thermal
stimuli. Thus, GSH administration can beneficially affect
diabetes in rats, while preserving in vivo kidney and neural
function. This suggests a potential usefulness of supplemental
glutathione to reduce diabetic complications in humans.
JOURNAL OF NUTRITION
2002;132(5):897-900.
14. Relationship between walnuts and
CHD
Four independent experts evaluated the scientific evidence
for a potential beneficial health relationship between the
intake of walnuts (and other tree nuts and legumes) and the
reduction and prevention of coronary heart disease (CHD).
Compared to most other nuts, which contain monounsaturated
fatty acids, walnuts are unique because they are rich in n-6
(linoleic acid) and n-3 (linolenic acid) polyunsaturated fatty
acids. Walnuts contain multiple health-beneficial components,
such as having a low lysine: arginine ratio and high levels of
arginine, folic acid, fiber, tannins and polyphenols. Though
walnuts are energy rich, clinical dietary intervention studies
show that walnut consumption does not cause a net gain in body
weight when eaten as a replacement food. Five controlled,
peer-reviewed, human clinical walnut intervention trials,
involving approximately 200 individuals representative of the
51% of the adult population in the United States at risk of
CHD were reviewed. The trials consistently demonstrated that
walnuts, being part of a heart-healthy diet, lower blood
cholesterol concentrations. None of these studies, however,
were of extended duration that would be essential for
evaluation of the sustainability of the outcomes.
Nevertheless, the results were supported by several large
studies in humans, all demonstrating a dose response-related
opposite association of the relative risk of coronary heart
disease with the frequent daily consumption of small amounts
of nuts, including walnuts.
JOURNAL OF NUTRITION
2002;132(5):1062S-1101S.
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