Cesarean Delivery: Lower Immunity Building in Infants?


  Cesarean delivery may result in lower bacterial diversity, lower abundance of the phylum Bacteroidetes, and lower circulating levels of Th1 chemokines in infants compared with vaginal delivery, according to a study published online August 7 in Gut. Lower diversity may lead to higher exposure to health risks such as allergies later in life.

Hedvig E. Jakobsson, MSc, from the KTH Royal Institute of Technology and Karolinska Institutet, Stockholm, Sweden, and colleagues followed-up 24 infants born by healthy women, 15 by vaginal delivery and 9 by cesarean delivery, from birth through age 24 months. The women and children were part of a larger study on prevention of allergies by probiotics, and 20 (83%) of the babies were partly breast-fed up until 6 months of age.

The researchers analyzed stool samples collected from the mothers 1 week after delivery and from the infants at 1 week and 1, 3, 6, 12, and 24 months after delivery. They compared microbial gene sequences isolated from mother and infant stool samples. They also collected venous blood samples from the infants at 6, 12, and 24 months of age. None of the infants received antibiotics, and any mothers who received antibiotics did so only after birth.

Although microbiota developed in a similar fashion at the phylum level for infants in both delivery-method groups, the researchers found that vaginal delivery infants had significantly higher proportions of Bacteroidetes than cesarean delivery infants, particularly at 1 week, 3 months, and 12 months. They also found moderately lower levels of Th1-associated chemokines in blood samples from cesarean delivery infants, which could increase risk for immune-mediated diseases such as allergy, diabetes, and inflammatory bowel disease.

This study comes only a few months after another study found that cesarean delivery, combined with lack of breast feeding, may negatively influence gut bacteria development and lead to health risks later in life.

“[Cesarean delivery] was associated with a lower diversity of the Bacteroidetes phylum when considering all time points (p=0.002),” the authors of the current study write.

“Our study corroborates earlier studies reporting a delayed colonization of Bacteroides in babies delivered by [cesarean delivery].” In addition, they write, the new gene sequencing data indicate that “specific lineages of the intestinal microbiota, as defined by 16S rRNA gene sequences, are transmitted from mother to child during vaginal delivery.”

The researchers point out that more knowledge of how delivery mode affects microbiota composition and building of immunity may lead to improved allergy prevention strategies.

Source: Gut.

 

DNA: the ‘smartest’ molecule in existence?.


DNA is the molecule that contains and passes on our genetic information. The publication of its structure on the 25th of April 1953 was vital to understanding how it achieves this task with such startling efficiency.

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In fact, it’s hard to think of another molecule that performs so many intelligent functions so effortlessly. So what is it that makes DNA so smart?

Multi-millennial survivor

For such a huge molecule, DNA is very stable so if it’s kept in cold, dry and dark conditions, it can last for a very, very long time. This is why we have been able to extract and analyse DNA taken from species that have been extinct for thousands of years.

Scientists have ‘resurrected’ blood protein from preserved mammoths after harvesting their DNA

It’s the double-stranded, double-helix structure of DNA that stops it falling apart.

DNA’s structure is a bit like a twisted ladder. The twisted ‘rails’ are made of sugar-phosphate, which give DNA its shape and protect the information carrying ‘rungs’ inside. Each sugar-phosphate unit is joined to the next by a tough covalent bond, which needs a lot of energy to break.

In between the ‘rails’, weaker hydrogen bonds link the two halves of the rungs together. Individually each hydrogen bond is weak – but there are thousands of hydrogen bonds within a single DNA molecule, so the combined effect is an extremely powerful stabilising force.

It’s this collective strength of DNA that has allowed biologists to study genes of ancient species like the woolly mammoth – extinct but preserved in the permafrost.

Our cells need to divide so we can grow and re-build, but every cell needs to have the instructions to know ‘how to be’ a cell.

Intelligent error correction

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The consequences of wrongly read or copied information can be disastrous and cause deformities in the proteins.

So as DNA replicates, enzymes carry out a proof-reading job and fix any rare errors.

They tend to repair about 99% of these types of errors, with further checks taking place later.

DNA provides those instructions – so a new copy of itself must be made before a cell divides.

It’s the super-smart structure that makes this easy. The ‘rungs’ of the DNA ladder are made from one of four nitrogen-based molecules, commonly known as A, T, G and C. These form complementary pairs – A always joins with T and G always joins with C.

So one side of the double-stranded DNA helix can be used as a template to produce a new side that perfectly complements it. A bit like making a new coat zip, but by using half of the old zip as a template.

The original side and the new one combine together to form a new DNA double helix, which is identical to the original.

Cleverly, human DNA can unzip and ‘replicate’ at hundreds of places along the structure at the same time – speeding up the process for a very long molecule.

Molecular contortionist

Two metres of DNA coils like a telephone cord to fit into each cell

DNA is one of the longest molecules in the natural world. You possess enough DNA, stretched out in a line, to reach from here to the sun and back more than 300 times.

Yet each cell nucleus must contain two metres of DNA, so it has to be very flexible. It coils – much like a telephone cord – into tight complex structures called chromatins without corrupting the vital information within.

DNA bases – vital rungs in the ladder

There are four different nucleotide bases in each DNA molecule:

  • Adenine (A)
  • Thymine (T)
  • Guanine (G)
  • Cytosine (C)

These small molecules join DNA together and encode our genetic information.

And despite being packed in so tightly, the genetic material can still be accessed to create new copies and proteins as required.

Human cells contain 23 pairs of chromosomes, with each containing one long DNA molecule as well as the proteins which package it. It’s no wonder DNA needs to be extremely supple.

Amazingly, this folded and packed form of DNA is approximately 10,000 times shorter than the linear DNA strand would be if it was pulled taut.

This is why we have the ‘luxury’ of having the plans for our entire body in nearly every cell.

Biological database

DNA storage

 

research team has encoded data in artificially produced segments of DNA, including:

  • A 26-second snippet of Martin Luther King’s classic anti-racism address from 1963
  • A .pdf” of the seminal 1953 paper by Crick and Watson describing DNA’ structure

The total data package was equivalent to 760 kilobytes on a computer drive. Physically, the DNA carrying all that information is no bigger than a speck of dust.

Genes are made up of stretches of the DNA molecule which contain information about how to build proteins – the building blocks of life which make up everything about us.

Different sequences of the four types of DNA bases make ‘codes’ which can be translated into the components of proteins, called amino acids. These amino acids, in different combinations can produce at least 20,000 different proteins in the human body.

Think of it like Morse Code. It too uses only four symbols (dot, dash, short spaces and long spaces), but it’s possible to spell out entire encyclopaedias with that simple code.

Just one gram of DNA can hold about two petabytes of data – the equivalent of about three million CDs.

That’s pretty smart, especially when you compare it to other information-storing molecules. Using the same amount of space, DNA can store 140,000 times more data than iron (III) oxide molecules, which stores information on computer hard drives.

DNA may be tiny but with properties including stability, flexibility, replication and the ability to store vast amounts of data, there’s a reason why it must be one of the smartest known molecules.

With huge quantities of data being produced by ever-growing computer systems, traditional data storage solutions, like magnetic hard drives are becoming bulky and cumbersome. Researchers have now used DNA to store artificially-produced information, but could this be the future of data storage?

Source: BBC

 

SSRI Use During Pregnancy Doesn’t Increase Mortality Risk in Offspring.


Use of selective serotonin reuptake inhibitors (SSRIs) during pregnancy is not associated with stillbirth or infant mortality, according to a JAMA study.

Using national registries in five Nordic countries, researchers identified women who filled a prescription for an SSRI from 3 months before they became pregnant through birth. Of 1.6 million births from 1996 to 2007, 1.8% of mothers had filled an SSRI prescription during pregnancy.

There were increased rates of stillbirth and postneonatal mortality among children whose mothers used SSRIs, but the authors say this could be explained by the severity of maternal psychiatric disease and maternal characteristics, such as smoking. After adjusting for these factors, SSRI use was not associated with an increased mortality risk.

Source: JAMA

UK, Japan scientists win Nobel for stem cell breakthroughs.


STOCKHOLM – Scientists from Britain and Japan shared a Nobel Prize on Monday for the discovery that adult cells can be transformed back into embryo-like stem cells that may one day regrow tissue in damaged brains, hearts or other organs.

John Gurdon, 79, of the Gurdon Institute in Cambridge, Britain and Shinya Yamanaka, 50, of Kyoto University in Japan, discovered ways to create tissue that would act like embryonic cells, without the need to harvest embryos.

They share the $1.2 million Nobel Prize for Medicine, for work Gurdon began 50 years ago and Yamanaka capped with a 2006 experiment that transformed the field of “regenerative medicine” – the field of curing disease by regrowing healthy tissue.

“These groundbreaking discoveries have completely changed our view of the development and specialization of cells,” the Nobel Assembly at Stockholm’s Karolinska Institute said.

All of the body’s tissue starts as stem cells, before developing into skin, blood, nerves, muscle and bone. The big hope for stem cells is that they can be used to replace damaged tissue in everything from spinal cord injuries to Parkinson’s disease.

Scientists once thought it was impossible to turn adult tissue back into stem cells, which meant that new stem cells could only be created by harvesting embryos – a practice that raised ethical qualms in some countries and also means that implanted cells might be rejected by the body.

In 1958, Gurdon was the first scientist to clone an animal, producing a healthy tadpole from the egg of a frog with DNA from another tadpole’s intestinal cell. That showed developed cells still carry the information needed to make every cell in the body, decades before other scientists made headlines around the world by cloning the first mammal, Dolly the sheep.

More than 40 years later, Yamanaka produced mouse stem cells from adult mouse skin cells, by inserting a few genes. His breakthrough effectively showed that the development that takes place in adult tissue could be reversed, turning adult cells back into cells that behave like embryos. The new stem cells are known as “induced pluripotency stem cells”, or iPS cells.

“The eventual aim is to provide replacement cells of all kinds,” Gurdon’s Institute explains on its website.

“We would like to be able to find a way of obtaining spare heart or brain cells from skin or blood cells. The important point is that the replacement cells need to be from the same individual, to avoid problems of rejection and hence of the need for immunosuppression.”

The science is still in its early stages, and among important concerns is the fear that iPS cells could grow out of control and develop into tumors.

Nevertheless, in the six years since Yamanaka published his findings the discoveries have already produced dramatic advances in medical research, with none of the political and ethical issues raised by embryo harvesting.

“NOT A ONE-WAY STREET”

Thomas Perlmann, Nobel Committee member and professor of Molecular Development Biology at the Karolinska Institute said: “Thanks to these two scientists, we know now that development is not strictly a one-way street.”

“There is lot of promise and excitement, and difficult disorders such as neurodegenerative disorders, like perhaps Alzheimer’s and, more likely, Parkinson’s disease, are very interesting targets.”

The techniques are already being used to grow specialized cells in laboratories to study disease, the chairman of the awards committee, Urban Lendahl, told Reuters.

“You can’t take out a large part of the heart or the brain or so to study this, but now you can take a cell from for example the skin of the patient, reprogram it, return it to a pluripotent state, and then grow it in a laboratory,” he said.

“The second thing is for further ahead. If you can grow different cell types from a cell from a human, you might – in theory for now but in future hopefully – be able to return cells where cells have been lost.”

Yamanaka’s paper has already been cited more than 4,000 times in other scientists’ work. He has compared research to running marathons, and ran one in just over four hours in March to raise money for his lab.

In a news conference in Japan, he thanked his team of young researchers: “My joy is very great. But I feel a grave sense of responsibility as well.”

Gurdon has spoken of an unlikely career for a young man who loved science but was steered away from it at school. He still keeps a discouraging school report on his office wall.

“I believe he has ideas about becoming a scientist… This is quite ridiculous,” his teacher wrote. “It would be a sheer waste of time, both on his part and of those who have to teach him.” The young John “will not listen, but will insist on doing his work in his own way.”

Source: Yahoo News

 

Scientists create replacement organs using body’s own cells.


One of the problems of organ transplants is the potential for the body to reject the foreign organ. For this reason, organ donor recipients have to take drugs that suppress the immune system.

Scientists are having preliminary success with a new way to get patients new organs that they may need: bioartificial organs made of plastic and the patient’s own cells.

So far, only a few such organs have been created and transplanted, and the they aren’t complex organs — just simples one like bladders and a windpipe. But, the New York Times reports, scientists are working on creating more complex organs such as kidneys and livers with these techniques.

A windpipe made to order

The Times article features the case of Andemariam Beyene, whose doctors discovered a golf ball-sized tumor growing in his windpipe two-and-a-half years ago. When he was nearly out of options for treatment, he went to see Dr. Paolo Macchiarini, at the Karolinska Institute in Stockholm, who suggested making Mr. Beyene a windpipe out of plastic and his own cells.

In order to make it, Dr. Macchiarini began by using a porous, fibrous plastic to make a copy of Mr. Beyene’s windpipe. He then seeded it with stem cells from Mr. Beyene’s bone marrow and placed the windpipe in an incubator that spun the windpipe “rotisserie-style,” says the Times, in a nutrient solution.

Then, he substituted that in for Mr. Beyene’s cancerous windpipe.

Fifteen months after surgery, Mr. Beyene is cancer-free.

The blueprint

Scientists are looking to nature to guidance on how to create these bioartificial organs.

In Dr. Macchiarini’s lab, a researcher named Philipp Jungebluth took a heart and lungs from a rat and put them in a glass jar. A detergent-like liquid connected via tube dripped into the jar and out, slowly stripping the organs of their living cells. After all the cells were gone (in three days), what was left of the organs was the scaffold, the basic shape of the organ, composed of a matrix of proteins and other compounds that keep the right cells in the right places.

Human scaffolds could be better for building new organs than synthetic scaffolds that just try to imitate nature. For example, donor lungs could be stripped of cells and re-seeded with a patient’s own cells before implantation.

Dr. Macchiarini has used scaffolds to successfully replace windpipes from cadavers in about a dozen patients who don’t have the major problem facing other organ donor recipients: the risk of organ rejection.

But scaffolds still have some problems of traditional organ transplants: They require donor organs, for which there is a long waiting list, and the patient has to wait for the organ to be stripped of cells. Also, when it comes to windpipes, a donated windpipe may not be the right size. For that reason, Mr. Beyene’s windpipe, made of the plastic replica of his own windpipe, fit perfectly.

Dr. Macchiarini is looking at future improvements on this still preliminary work: The Times reports that someday, re-seeding the cells of a new organ may not take place outside the body:

“Instead, he envisions developing even better scaffolds and implanting them without cells, relying on drugs to stimulate the body to send cells to the site. His ultimate dream is to eliminate even the synthetic scaffold. Instead, drugs would enable the body to rebuild its own scaffold.”

“Don’t touch the patient,” Dr. Macchiarini told The Times. “Just use his body to recreate his own organ. It would be fantastic.”

Source: The New York Times /Smart planet