Обычная пищевая добавка изменяет кишечную микробиоту у мышей

Было обнаружено, что обычная пищевая добавка, недавно запрещенная во Франции, но разрешенная в США и многих других странах, значительно изменяет кишечную микробиоту у мышей, вызывая воспаление толстой кишки и изменения в экспрессии белка в печени, согласно исследованиям, проведенным под руководством учёного Массачусетского университета Амхерст.

Вместе с коллегами из Umass Amherst и в Китае, Сяо опубликовал исследование в Small, еженедельно рецензируемом междисциплинарном журнале, который охватывает нанотехнологии.

Кишечная микробиота, которая относится к разнообразному и сложному сообществу микроорганизмов в кишечнике, играет жизненно важную роль в человеческом здоровье. Дисбаланс кишечной микробиоты связан с целым рядом проблем здоровья, включая воспалительные заболевания кишечника, ожирение и сердечно-сосудистые заболевания.

Воздействие АЭС Tio2 на человека происходит главным образом от пищевой добавки, известной как E171, которая состоит из частиц Tio2 различного размера, включая одну треть или более наноразмерных частиц. E171, что делает продукты более белыми и более непрозрачными, встречается в таких продуктах, как десерты, конфеты, напитки и жвачка. E171 экспозиция в 2-4 раза выше у детей в США, чем у взрослых. Сяо указывает, что одно исследование было найдено.

Наноразмерные частицы фосодера размером менее 100 нанометров могут иметь уникальные физиологические свойства, вызывающие обеспокоенность. "Большие частицы не будут легко впитываться, но меньшие могут попасть в ткани и где-то накапливаться", - говорит Сяо.

В своих исследованиях Сяо и его команда кормили двумя популяциями мышей либо E171, либо Tio2 NP. Одному населению был предоставлен режим питания с высоким содержанием жиров, аналогичный режиму питания многих американцев, две трети которых страдают ожирением или избыточным весом; другая группа мышей питалась диетой с низким содержанием жира. Мыши питались диетой с высоким содержанием жира, но в конечном итоге стали тучными, в то время как мыши с низким содержанием жира - нет.

Исследователи обнаружили, что NP Tio2 понизили цекальные уровни короткоцепных жирных кислот, которые необходимы для здоровья толстой кишки, и увеличили пропорциональные иммунные клетки и цитокины в толстой кишке, что указывает на воспалительное состояние.

Для оценки прямого воздействия микробиоты кишечника на здоровье, нарушенной Tio2 NP, Сяо и его коллеги провели исследование фекальной трансплантации. Они давали мышам антибиотики, чтобы очистить их первобытную кишечную микробиоту, а затем пересаживали фекальные бактерии из Tio2 NP-обработанных мышей в обработанных антибиотиками мышей. "Результаты подтверждают нашу гипотезу о том, что включение АЭС Tio2 в диету нарушает гомеостаз кишечной микробиоты", - говорит Сяо, - "что, в свою очередь, приводит к воспалению мышей."

В ходе исследования были также измерены уровни Тио2 в образцах табуретов человека, что позволило выявить широкий диапазон. Сяо говорит, что необходимы дальнейшие исследования для определения последствий воздействия ЯИЭ Tio2 на здоровье человека в долгосрочной перспективе - например, в течение всей жизни и в течение нескольких поколений.

 

 

БИЛЕТ 4

1. High Blood Pressure in Children. By Sally Robertson, B.Sc.

 

Although people usually assume that only middle-aged or elderly people develop high blood pressure (hypertension), it is also possible for the condition to arise in teenagers, children and even babies.

The American Heart Association advises that all children should be checked for high blood pressure on a yearly basis, as detecting the condition and treating it early will improve the child’s health and reduce or prevent the harmful effects of the condition.

Causes

Hypertension in children is usually caused by another underlying health condition such as heart disease or kidney disease. Itis therefore referred to as secondary hypertension and once the medical condition is resolved, the blood pressure typically returns to normal. Secondary hypertension may also be caused by the following conditions:

Hyperthyroidism

Adrenal disorder

Sleep problems, particularly sleep apnea

Renal artery stenosis

Some medications can increase blood pressure, but, again, the blood pressure usually returns to normal if the medication is discontinued.

In some cases, a doctor cannot determine what is causing the hypertension, in which case the condition is referred to as primary or essential hypertension. Various factors that are known to contribute to the risk of primary hypertension include:

Overweight or obesity (body mass index >25)

Family history of hypertension

High cholesterol and triglycerides

Type 2 diabetes or raised fasting blood sugar

Complications

Children with hypertension often develop sleep apnea and breathe abnormally while they sleep, particularly if the child is overweight. If the hypertension persists into adulthood, the person is at an increased risk of kidney disease, stroke, heart attack and heart failure.

Tests and diagnosis

Blood pressure is measured using an inflatable arm cuff and blood pressure gauge. The blood pressure measurement is made up of two readings. The first (upper) number is a measurement of systolic blood pressure, which is the pressure in the arteries when the heart beats. The second (lower) number is a measurement of the diastolic pressure, which is the pressure in the arteries between heartbeats.

One blood pressure measurement is not sufficient to diagnose hypertension. In order to be diagnosed, the child needs to have an abnormal reading on at least three visits to the doctor, and during a visit, the measurement may be taken several times to ensure it is accurate.

 

What is considered as “normal” blood pressure is relative and depends on the child’s gender, age and height. If hypertension is diagnosed, the child should then be checked approximately every six months. A doctor may also perform the following tests to check for other underlying conditions that may be causing the problem:

Echocardiogram to check blood flow through the heart

Ultrasound to assess the kidneys

Blood test to check blood cell counts, blood glucose and function of the kidneys

Urine analysis

Treatment

Hypertension in children is generally managed by making lifestyle changes such as exercising regularly, eating a diet that is good for the heart and maintaining a healthy weight. If these measures alone are not enough to resolve the problem, medications may be prescribed.

 

2. Detecting Brain Disease Using the Eye. By Susha Cheriyedath, M.Sc.

 

The human eye shares several vascular and neural similarities to the brain, and hence, our eyes have been found to offer a direct window to brain pathology. The unique characteristics of our eyes allow them to be a relatively affordable biomarker for Alzheimer's disease (AD) and other illnesses of the brain.

Currently, the diagnosis of AD is only possible after patients start showing early cognitive loss. A formal diagnosis is made using cognitive or mental state examinations, but the diagnosis can only be confirmed after examining the brain post mortem.

Well-established biomarkers for AD presently used include Aβ-42, T-tau, and p-tau found in the cerebrospinal fluid, and fluorodeoxyglucose and Pittsburg Compound B found in the brain. Although these biomarkers are crucial for AD monitoring, the widespread implementation of these biomarkers is still a challenge.

Visual biomarkers for AD

Alzheimer's patients usually report visual symptoms, and this encouraged scientists to look for potential ocular biomarkers for AD. Studies showed that certain visual symptoms could be an indication of dementia onset as well as the development of senile plaques in the visual regions in the brain.

As more and more details about the sequence of events, as well as the neurodegenerative changes in AD, are discovered, structural retinal biomarkers were found to have the potential to help in the early diagnosis of AD. Commonly reported vascular issues in AD are a blood-brain-barrier compromise, impaired Aβ clearance, vasoconstriction, reduced blood vessel density, and blood flow.

Direct visualization of the hallmarks of AD in the retina can be the most promising AD biomarker because of its specificity for AD. However, ongoing work is necessary to verify that Aβ plaques are present in retinal tissues and that these retinal deposits are predictive of cerebral deposits. In addition, VVAD, a visual variant of AD, has been found to affect relatively younger people. VVAD patients present with visual symptoms in their 50s or 60s and eventually follow the course of cognitive decline typically seen in patients with AD.

Non-retinal biomarkers for AD include pupillary reactions such as pupil size and pupillary response to light. Eye movements also play a crucial role because AD patients have trouble with reading due to suboptimal eye movements said to be linked to memory. AD sufferers have been shown to present with higher latency during voluntary eye movements, and show decreased eye movement speed. They may also fail to fixate on or follow a moving target.

Apart from being crucial and early indicators of brain illness, these visual changes are easy to examine since the eye is very accessible, and retinal imaging is a simple procedure, all of which make ocular biomarkers very attractive.

 

БИЛЕТ 5

1. Can Antibiotics Increase the Risk of Arthritis? By Ratan-NM

 

Rheumatoid arthritis (RA) is an autoimmune disorder that causes inflammation of the joints. RA is a chronic and progressive condition that causes debilitating effects on the patient. The condition is characterized by pain and stiff joints.

Another typical feature of this disorder is bone and joint destruction and the presence of autoantibodies in the serum and synovial fluid. Synovial fluid is the fluid that lubricates the synovial joints.

What causes rheumatoid arthritis?

The exact mechanism by which patients develop RA is unknown; however, a combination of genetic and environmental factors is likely. Autoimmune antibody production is proposed to be the main mechanism responsible for bone and joint destruction, and the related RA pathology. Infections, hormonal alterations, and stress are some potential triggers of RA.

Recent research suggests an association between antibiotic use, gut microbiota changes, and RA flares.

Antibiotics and the gut microbiota

Antibiotics are widely used for the treatment of bacterial infections associated with the respiratory system, gastrointestinal system, and urinary tract. Although antibiotics act against pathogenic bacteria, they can also modify the normal gut microbiota.

The gut microbiota is a diverse system of microorganisms residing in the gastrointestinal tract of the human body. Gut microbiota plays a vital role in maintaining the body’s digestive health. Gut microbiota is also involved in the immune system and the synthesis of vitamin B and vitamin K.

Various epidemiological studies have demonstrated associations between the occurrence of bacterial infections and RA. Furthermore, microbiome alterations have been indicated as a potential mechanism for the effect of infection in RA pathogenesis. Antibiotics substantially disturb the gut microbiome, with studies demonstrating significant microbial shifts in the gastrointestinal tract following their use.

The alterations in the gut microbiome may last up to a year after treatment periods of only one week. As per a recent study by Nagra et al., the risk of RA flare was significantly increased in the 1–12 months after commencing treatment on sulphonamide and trimethoprim antibiotics.

Antibiotic usage and the risk of rheumatoid arthritis

Emerging research suggests that infections are potential risk factors for RA pathogenesis and flares. Respiratory infections have been particularly linked with the development of RA. Antibodies to citrullinated peptide antigens (ACPA) are one of the autoantibodies associated with RA.

ACPAs have been found to be produced in response to certain bacterial components, which suggests the potential role of infections in RA pathogenesis.

2. Brain Activity During Sleep. By Yolanda Smith.

Although it was historically believed that sleep was a passive but necessary process for healthy bodily functions, it is now known that brain activity continues during sleep. In fact, this brain activity is thought to play several important roles in the maintenance of physical, emotional and mental health.

Brainwaves in Sleep Stages. There are different stages of sleep, each of which is characterized by unique brain activity. Stage 1 sleep is the lightest stage of sleep that occurs as an individual is falling asleep. There is slow movement of the eyes and activity of the voluntary muscles in the body is reduced. The brainwaves in stage 1 sleep are smaller and more uniform than in the awake state, what are referred to as alpha and theta waves.

In stage 2 sleep, the movement of the eyes ceases and the brain waves become slower than in stage 1. There are also occasional bursts of waves that are more rapid, which are referred to as sleep spindles.

Stage 3 of sleep is characterized by slow, rhythmical brain waves called delta waves. This stage of sleep is very heavy with no movement of the eyes or voluntary muscles, and it is difficult to wake a person in this stage.

During REM sleep, an individual usually breathes more rapidly and there are quick movements of the eyes that characterize the state. In this stage, the brain activity is very similar to that of a person who is awake, suggesting that there are significant processes taking place in the central nervous system.

REM Brain Activity. It is believed that dreaming occurs for at least 2 hours each night during REM sleep and this activity plays an important role in the processing of information and creation of memory. During this stage of sleep, heart rate and blood pressure increase and the activity of the brain is markedly more dynamic. Sleep research with EEG monitoring has established that infants spend a greater proportion of sleep time (up to 50%) in comparison to adults, leading to the hypothesis that the brain activity helps in the development of the memory and learning.

The signals initiate at the base of the brain, in an area referred to as the pons, and then expand to the thalamus and cerebral cortex. The cerebral cortex is responsible for processes of learning, thinking and organizing information.

Sleep Stage Cycles. Over time, an individual progresses through the different stages of sleep and the activity of the brain changes accordingly. It begins with stage 1 for about 5-10 minutes, then stage 2 for about 10 minutes, then stage 3 for about 30 minutes, before reaching REM sleep more than an hour after first falling asleep.

Shortly after, the individual returns to stage 2 sleep, then stage 3 sleep and then REM sleep once again, repeating this cycle approximately five times before awakening.

It is unclear why this cycling through the stages of sleep and continual changes in the brain activity is required for the healthy function of humans and other mammals. Further research in this area is currently being undertaken to understand this area more comprehensively, particularly for the function of the brain activity.

БИЛЕТ 6