User:GeorgeVKach/sandbox

Assignment 3

 Original- "Gut Flora" 

Acquisition of gut flora in human infants
In humans, a gut flora similar to an adult's is formed within one to two years of birth. The gastrointestinal tract of a normal fetus is considered sterile, but microbial colonisation may occur in the fetus and Lactobacillus and Bifidobacterium species were present in placental biopsies in one study. During birth and rapidly thereafter, bacteria from the mother and the surrounding environment colonize the infant's gut. As of 2013, it was unclear whether most of colonizing arise from the mother or not. Infants born by caesarean section may also be exposed to their mothers' microflora, but the initial exposure is most likely to be from the surrounding environment such as the air, other infants, and the nursing staff, which serve as vectors for transfer. During the first year of life, the composition of the gut flora is generally simple and it changes a great deal with time and is not the same across individuals.

The initial bacterial population are generally facultative anaerobic organisms; investigators believe that these initial colonizers decrease the oxygen concentration in the gut, which in turn allows purely anaerobic bacteria like Bacteroides, Actinobacteria, and Firmicutes to become established and thrive. Breast-fed babies become dominated by bifidobacteria, possibly due to the contents of bifidobacterial growth factors in breast milk, and by the fact that breast milk carries prebiotic components, allowing for healthy bacterial growth. In contrast, the microbiota of formula-fed infants is more diverse, with high numbers of Enterobacteriaceae, enterococci, bifidobacteria, Bacteroides, and clostridia.

Copied from Gut flora

 Edit- "Gut Flora" 

Acquisition of gut flora in human infants
The establishment of a gut flora is crucial to the health of an adult, as well the functioning of the gastrointestinal tract. In humans, a gut flora similar to an adult's is formed within one to two years of birth.

The traditional view of the gastrointestinal tract of a normal fetus is that it is sterile. However, this view has been challenged in the past few years. Multiple lines of evidence have begun to emerge that suggest there may be bacteria in the intrauterine environment. In humans, research has shown that microbial colonization may occur in the fetus with one study showing Lactobacillus and Bifidobacterium species were present in placental biopsies. Several rodent studies have demonstrated the presence of bacteria in the amniotic fluid and placenta, as well as in the meconium of babies born by sterile cesarean section In another study, researchers administered a culture of bacteria orally to a pregnant dam, and detected the bacteria in the offspring. However, researchers caution that the source of these intrauterine bacteria, whether they are alive, and their role, is not yet understood.

During birth and rapidly thereafter, bacteria from the mother and the surrounding environment colonize the infant's gut. The exact sources of bacteria is not fully understood, but may include the birth canal, other people (parents, siblings, hospital workers), breastmilk, food, and the general environment with which the infant interacts. However, as of 2013, it remains unclear whether most of colonizing arise from the mother or not. Infants born by caesarean section may also be exposed to their mothers' microflora, but the initial exposure is most likely to be from the surrounding environment such as the air, other infants, and the nursing staff, which serve as vectors for transfer.

During the first year of life, the composition of the gut flora is generally simple and it changes a great deal with time and is not the same across individuals. The initial bacterial population are generally facultative anaerobic organisms; investigators believe that these initial colonizers decrease the oxygen concentration in the gut, which in turn allows purely anaerobic bacteria like Bacteroides, Actinobacteria, and Firmicutes to become established and thrive. Breast-fed babies become dominated by bifidobacteria, possibly due to the contents of bifidobacterial growth factors in breast milk, and by the fact that breast milk carries prebiotic components, allowing for healthy bacterial growth. In contrast, the microbiota of formula-fed infants is more diverse, with high numbers of Enterobacteriaceae, enterococci, bifidobacteria, Bacteroides, and clostridia.

Several other factors may influence the colonization pattern and the kind of bacteria that establish the gut flora. These factors include the delivery mode (vaginal versus cesarean section), being held in a neonatal intensive care unit, sanitary conditions, as well as presence of siblings in the family. Children treated with antibiotics have less stable, and less diverse floral communities. Various methods of microbiome restoration after cesarean section, antibiotics, or formula feeding are being explored, and typically involve exposing the infant to maternal vaginal contents, and oral probiotics.

~

Assignment 2

The gut flora topic is of high notability: there is a significant amount of coverage on the topic, and the present Wikipedia article has numerous reliable references including textbooks and research articles from reputable journals (including The Lancet and Nature, which are known for their stringent standards and high impact factor). Gut flora is an area of vibrant research independent of the subject. However, there is some information in the Wikipedia article that is out of date and which can be expanded upon.

The “Acquisition of gut flora in human infants” subheading is presently surprisingly short. Furthermore, the present entry states that the fetal gastrointestinal (GI) tract is considered sterile, and only briefly mentions that some microbial colonization can occur. This statement is a bit out of date: there is growing evidence that the uterine environment is not sterile.

Several studies have demonstrated the presence of bacteria in the amniotic fluid and placenta, as well as in the meconium of babies born by sterile cesarean section. Rat studies have also been used to confirm that mothers can transmit bacteria to children: in one study, a culture of bacteria were administered orally to a pregnant dam, and then detected in the offspring. This has many implications, one of which is the fact that if the mothers microbiome were to change, she could pass on those changes her offspring. For example, a high fat maternal diet leads to an altered offspring gut microbiome in primates, an effect also observed in human babies born to mothers consuming a high fat diet.

While the actual mechanism behind this transfer of dysbiosis is not yet clear, this contrasts with what the present Wikipedia article suggests, and is therefore worth mentioning.

I will be updating and expanding the article to reflect more closely the current state of knowledge.

~

Assignment 5: Incorporating Feedback

Acquisition of gut flora in human infants
The establishment of a gut flora is crucial to the health of an adult, as well the functioning of the gastrointestinal tract. In humans, a gut flora similar to an adult's is formed within one to two years of birth.

The traditional view of the gastrointestinal tract of a normal fetus is that it is sterile, although this view has been challenged in the past few years. Multiple lines of evidence have begun to emerge that suggest there may be bacteria in the intrauterine environment. In humans, research has shown that microbial colonization may occur in the fetus with one study showing Lactobacillus and Bifidobacterium species were present in placental biopsies. Several rodent studies have demonstrated the presence of bacteria in the amniotic fluid and placenta, as well as in the meconium of babies born by sterile cesarean section. In another study, researchers administered a culture of bacteria orally to a pregnant dam, and detected the bacteria in the offspring, likely resulting from transmission between the digestive tract and amniotic fluid via the blood stream. . However, researchers caution that the source of these intrauterine bacteria, whether they are alive, and their role, is not yet understood.

During birth and rapidly thereafter, bacteria from the mother and the surrounding environment colonize the infant's gut. The exact sources of bacteria is not fully understood, but may include the birth canal, other people (parents, siblings, hospital workers), breastmilk, food, and the general environment with which the infant interacts. However, as of 2013, it remains unclear whether most colonizing arises from the mother or not. Infants born by caesarean section may also be exposed to their mothers' microflora, but the initial exposure is most likely to be from the surrounding environment such as the air, other infants, and the nursing staff, which serve as vectors for transfer. During the first year of life, the composition of the gut flora is generally simple and changes a great deal with time and is not the same across individuals. The initial bacterial population are generally facultative anaerobic organisms; investigators believe that these initial colonizers decrease the oxygen concentration in the gut, which in turn allows obligately anaerobic bacteria like Bacteroides, Actinobacteria, and Firmicutes to become established and thrive. Breast-fed babies become dominated by bifidobacteria, possibly due to the contents of bifidobacterial growth factors in breast milk, and by the fact that breast milk carries prebiotic components, allowing for healthy bacterial growth. In contrast, the microbiota of formula-fed infants is more diverse, with high numbers of Enterobacteriaceae, enterococci, bifidobacteria, Bacteroides, and clostridia.

Caesarean section, antibiotics, and formula feeding may alter the gut microbiome composition. Children treated with antibiotics have less stable, and less diverse floral communities. Caesarean sections have been shown to be disruptive to mother-offspring transmission of bacteria, which impacts the overall health of the offspring by raising risks of disease such as celiacs, asthma, and type 1 diabetes. This further evidences the importance of a healthy gut microbiome. Various methods of microbiome restoration are being explored, typically involving exposing the infant to maternal vaginal contents, and oral probiotics.