Tuyển tập các báo cáo nghiên cứu về sinh học được đăng trên tạp chí sinh học Journal of Biology đề tài: Genetic effects of static magnetic fields. Body size increase and lethal mutations induced in populations of Drosophila melanogaster after chronic exposure
Bacterial biofilms are regarded to be the primary aetiological factor in the initiation of
gingival inflammation and subsequent destruction of periodontal tissues (Offenbacher 1996)
and three major specific pathogens have been repeatedly identified as etiologic agents,
namely Aggregatibacter (Actinobacillus) actinomycetemcomitans (Aa), Porphyromonas gingivalis
(Pg) and Tannerella forsythia (Tf) (Socransky et al. 1998).
For benefits of chronic alcohol consumption, see page 187. Central nervous system. The development of dependence on alcohol appears to involve alterations in central nervous system neurotransmission. The acute effect of alcohol is to block NMDA receptors for which the normal agonist is glutamate, the main excitatory transmitter in the brain. Chronic exposure increases the number of NMDA receptors and also 'L type' calcium channels, while the action of the (inhibitory) GABA neurotransmitter is reduced.
Investor base: participation by different investors in the government bond market has grown
more diversified. Of the various actors in this market, banks tend to invest in relatively
shorter term bonds to match their short-term liability. Pension funds and insurance
companies prefer hedging long-term inflation risks by investing more in inflation linked
bonds. Non-residents concentrate their direct exposure to fixed rate instruments, but with
maturity less than 3 years.
This paper focuses on developing an empirical strategy for measuring the effect of pollution on
health. Specifically, I look at the effect of air pollution on children's hospitalization for asthma. Childhood
asthma is of particular interest for two reasons: 1) asthma is the leading chronic condition affecting children;
and 2) current pollution standards are based on adult health responses to pollution and children face a greater
risk from pollution exposure due to the sensitivity of their developing biological systems.
This study builds on earlier work in five ways.
The term stress was introduced into the biomedical field by Hans Selye (1936) in reference to
a General Adaptation Syndrome which would consist of all non-specific systemic reactions
that occur during an intense and chronic exposure to a stressor (e.g., pressure at work and
poor diet). This syndrome would be different from the specific adaptive reactions (such as
muscle hypertrophy caused by exercise performed on a regular basis) and immune
responses (Selye, 1936).
Estuaries are areas of high productivity, crucial in the life histories of many fish,
invertebrates, and birds, for example, and the sustainability of estuarine biodiversity
is vital to the ecological and economic health of coastal regions. On the other
hand, estuarine ecosystems are exposed to toxic anthropogenic effluents transported
by rivers from remote and nearby conurbations and industrial and agricultural concerns.
Over the past 25 years the discipline of ecotoxicology has undergone two
major developments. Firstly, new assays have been developed, deploying
organisms that bear added relevance to the specific environment under
investigation. Several new procedures assess the effects on organisms after
exposure to environmental samples rather than to spiked water or sediment
samples. Also noteworthy is the considerable attention given to effects of
chronic exposure to low levels of contaminants.
Sulfur trioxide irritates the mucous membranes of the respiratory tract. A concentration of 1
volume of SO3 in a million volumes of air (one part per million or 1 ppm) is enough to
cause coughing and choking. Sulfur trioxide dissolves in water to form sulfuric acid,
which is a strong acid capable of corroding or destroying many materials. Sulfur trioxide
can absorb moisture from the atmosphere to form very fine droplets of sulfuric acid.
Inhalation of these droplets can harm the respiratory system. Chronic exposure leads to a
much greater likelihood of suffering from bronchitis.
The National Council on Radiation Protection and Measurements
(NCRP) was requested by the US Department of Energy (DOE) to
review the literature on the effects of radiation on aquatic organisms
and develop a document that reviews the present understanding of
such effects and provides guidance for a standard for the protection of
populations of aquatic organisms.
The population exposure without PM10 fraction attributable to road traffic is shown in Figure 6.
Compared to total PM10, the frequency distribution changes considerably. Most people would live in
areas with PM10 values less than 20 µg/m3. In France and Switzerland, less than 3% of the population
would live in areas with PM10 greater than 20 µg/m3. In Austria, this portion is higher due to an
increased non-traffic caused regional PM10 background.
A study of physician office visits in London showed associations between air pollution
and doctor visits for asthma and other lower respiratory disease. For children, levels of
nitrogen dioxide, carbon monoxide, and sulfur dioxide were associated with increased
numbers of medical consultations. However, in adults, the only consistent association
was with levels of airborne particles. This suggests that children and adults might
respond differently to pollution exposures.
Prenatal Effects of Carbon Monoxide
Carbon monoxide may also have prenatal effects.
In the fully watered camel thyroid activity is higher in summer than in winter, but activity
is reduced in camels deprived of water. The decline in activity is important because the
generation of metabolic heat is reduced and respiratory water losses are also reduced.
Chronic exposure to heat results in depressed thyroid activity as well as reduced plasma,
cortisol and growth hormone concentrations and turnover rates. All three sources
normally create heat and act in cooperation, so the net result of habituation to heat is
some reduction in metabolic rate (Wilson, 1998). ...
The main risks in acute poisoning are: hyperpyrexia, tachycardia, and a rise in the metabolic
rate leading to death by cardiac arrest. In chronic exposure, the main riss are: skin, blood,
neurological and respiratory disorders, porphyria, non-specific symptoms, and the possibility of
Tuyển tập các báo cáo nghiên cứu về y học được đăng trên tạp chí y học 'Respiratory Research cung cấp cho các bạn kiến thức về ngành y đề tài:" Characterisation of the proximal airway squamous metaplasia induced by chronic tobacco smoke exposure in spontaneously hypertensive rat...
Tuyển tập các báo cáo nghiên cứu về y học được đăng trên tạp chí y học 'Respiratory Research cung cấp cho các bạn kiến thức về ngành y đề tài:: " Regional differences in the pattern of airway remodeling following chronic allergen exposure in mice...
Limited data suggest that the risk of squamous cell carcinoma is similarly increased after first use
as a teenager. Artificial tanning confers little if any protection against solar damage to the skin, nor
does use of indoor tanning facilities grant protection against vitamin D deficiency. Data also suggest
detrimental effects from use of indoor tanning facilities on the skin’s immune response and possibly
on the eyes (ocular melanoma).
Knowledge of levels of UV exposure during indoor tanning is very imprecise.
Tuyển tập các báo cáo nghiên cứu về y học được đăng trên tạp chí y học Critical Care giúp cho các bạn có thêm kiến thức về ngành y học đề tài: Chronic productive cough in school children: prevalence and associations with asthma and environmental tobacco smoke exposure...