By analyzing bacterial communities in and on several people, scientists have begun to create an atlas of bacterial diversity that documents the different types of microbes that thrive in distinct regions of the human body. This research sets the stage for determining how changes in bacterial communities help to cause or prevent disease.

Our bodies play host to a wide variety of microbes, called the human microbiota, that outnumber our own cells by about 10 to 1. Many of these microbes help us stay healthy—for instance by aiding digestion or crowding out disease-causing microbes. But details about how microbial communities vary in different body regions, among people or over time are not yet well understood.

In a study funded in part by NIH’s National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), Dr. Rob Knight and his colleagues at the University of Colorado, Boulder, and George Washington University, St. Louis, began to chart a baseline map of the human microbiota in healthy people. The results were published on November 5, 2009, in the advance online edition of Science.

The scientists surveyed bacterial communities in up to 27 different locations on the bodies of 9 healthy adults. Sampled regions included hair on the head, ear canals, nostrils, mouth, lower gut and 18 different skin sites ranging from foreheads and armpits to navels and feet. Swabs from these regions were collected 4 times over 3 months.

As in other recent studies of the human microbiota, Knight and colleagues identified bacteria by extracting DNA from each sample and then analyzing a bacteria-specific gene, called the 16S ribosomal RNA gene. Overall, the detected microbes belong to 22 bacterial phyla. Four phyla were dominant, representing more than 90% of the identified bacteria.

The researchers found wide variability in bacterial communities on each person and between people. The greatest diversity over time was seen on hair, nostril and ear canal sites, as well as some skin regions, especially the forearms, palm, index finger, back of the knee and sole of the foot. These regions were also the most divergent between people, as was the lower gut. The mouth had the least bacterial variability of any tested region.

The researchers also tested how well bacteria from one body region could survive on another. They transferred bacteria from the tongue to the disinfected forearms and foreheads of some volunteers and tracked them for up to 8 hours. Tongue bacteria persisted longer on the forearms than foreheads, suggesting that the oily forehead may be too harsh a habitat for some bacteria. Bacterial communities transplanted from forehead to forearms and vice versa could not survive well in the new habitats, coming to resemble the native mix rather than the transplants within hours.

“This is the most complete view we have yet of the microbial side of ourselves, one that our group and others will be adding to over the coming years,” says Knight. “If we can better understand this variation, we may be able to begin searching for biomarkers for disease.”

—by Vicki Contie

Reference:
National Institutes of Health (November 16, 2009) Wide variety of bacteria mapped across the human body.  Retrieved November 16, 2009 from http://www.nih.gov/researchmatters/november2009/11162009bacteria.htm

Intensive Glucose Control Reduces Complications of Type 1 Diabetes
Near-normal control of glucose beginning as soon as possible after diagnosis greatly improves the long-term prognosis of type 1 diabetes, a new study found.

Nearly 24 million people nationwide have diabetes, with type 1 diabetes accounting for about 5-10% of confirmed cases. Formerly called juvenile-onset or insulin-dependent diabetes, type 1 diabetes develops when the body’s immune system destroys the cells that make the hormone insulin, which regulates blood glucose. Type 1 diabetes develops most often in children and young adults but can appear at any age.

The new study builds on the landmark Diabetes Control and Complications Trial (DCCT) and its follow-up study, the Epidemiology of Diabetes Interventions and Complications (EDIC). Both were funded by NIH. DCCT, conducted from 1983 to 1989, compared intensive management of blood glucose to conventional control. The intensive treatment group was asked to keep glucose levels as close to normal as possible, which requires at least 3 insulin injections a day or an insulin pump, guided by self-monitoring of blood glucose at least 4 times a day. At the time, conventional treatment consisted of 1 or 2 insulin injections a day with daily urine or blood glucose testing. DCCT found that intensive glucose control was superior to conventional control in delaying or preventing the complications of type 1 diabetes. EDIC continues to follow DCCT participants to track the long-term effects of the approaches.

In the new study, a team of researchers led by Dr. David M. Nathan of Massachusetts General Hospital and Dr. Trevor Orchard of the University of Pittsburgh looked at overall rates of eye, kidney and cardiovascular complications in people who were diagnosed with type 1 diabetes an average of 30 years earlier. The team looked at DCCT/EDIC participants as well as a subset of patients from another NIH-funded study of people diagnosed with type 1 diabetes from 1950 to 1980. The other study was observational, with the patients comparable to DCCT participants using conventional treatment.

In the July 27, 2009, issue of the Archives of Internal Medicine, the researchers reported that intensive glucose control significantly lowered rates of eye damage, kidney damage and cardiovascular disease events. Among DCCT participants, those randomly assigned to intensive glucose control had about half the rate of eye damage after 30 years of diabetes than those assigned to conventional glucose control (21% vs. 50%), less than half the rate of kidney damage (9% vs. 25%) and a lower rate of cardiovascular events (9% vs. 14%). Results from the other NIH-funded study were consistent with those from DCCT’s conventionally treated participants.

The researchers also found that, after 30 years of living with diabetes, less than 1% of those receiving intensive glucose control in the DCCT had significantly impaired vision or kidney failure or needed a limb amputation due to diabetes.

“Tight control is difficult to achieve and maintain, but its benefits have changed the course of diabetes,” says Dr. Saul Genuth of Case Western University, who co-chairs the EDIC study. Major technology improvements in the past decade, such as continuous glucose monitoring devices and improved insulin pump technology, are now helping patients control their blood glucose more precisely and conveniently.

Related Links:
Type 1 Diabetes:

http://health.nih.gov/result.asp?terms=diabetes&disease_id=379

DCCT and EDIC:
http://diabetes.niddk.nih.gov/dm/pubs/control/ Intensive Glucose Control Reduces Complications of Type 1 Diabetes
Near-normal control of glucose beginning as soon as possible after diagnosis greatly improves the long-term prognosis of type 1 diabetes, a new study found.

Nearly 24 million people nationwide have diabetes, with type 1 diabetes accounting for about 5-10% of confirmed cases. Formerly called juvenile-onset or insulin-dependent diabetes, type 1 diabetes develops when the body’s immune system destroys the cells that make the hormone insulin, which regulates blood glucose. Type 1 diabetes develops most often in children and young adults but can appear at any age.

The new study builds on the landmark Diabetes Control and Complications Trial (DCCT) and its follow-up study, the Epidemiology of Diabetes Interventions and Complications (EDIC). Both were funded by NIH. DCCT, conducted from 1983 to 1989, compared intensive management of blood glucose to conventional control. The intensive treatment group was asked to keep glucose levels as close to normal as possible, which requires at least 3 insulin injections a day or an insulin pump, guided by self-monitoring of blood glucose at least 4 times a day. At the time, conventional treatment consisted of 1 or 2 insulin injections a day with daily urine or blood glucose testing. DCCT found that intensive glucose control was superior to conventional control in delaying or preventing the complications of type 1 diabetes. EDIC continues to follow DCCT participants to track the long-term effects of the approaches.

In the new study, a team of researchers led by Dr. David M. Nathan of Massachusetts General Hospital and Dr. Trevor Orchard of the University of Pittsburgh looked at overall rates of eye, kidney and cardiovascular complications in people who were diagnosed with type 1 diabetes an average of 30 years earlier. The team looked at DCCT/EDIC participants as well as a subset of patients from another NIH-funded study of people diagnosed with type 1 diabetes from 1950 to 1980. The other study was observational, with the patients comparable to DCCT participants using conventional treatment.

In the July 27, 2009, issue of the Archives of Internal Medicine, the researchers reported that intensive glucose control significantly lowered rates of eye damage, kidney damage and cardiovascular disease events. Among DCCT participants, those randomly assigned to intensive glucose control had about half the rate of eye damage after 30 years of diabetes than those assigned to conventional glucose control (21% vs. 50%), less than half the rate of kidney damage (9% vs. 25%) and a lower rate of cardiovascular events (9% vs. 14%). Results from the other NIH-funded study were consistent with those from DCCT’s conventionally treated participants.

The researchers also found that, after 30 years of living with diabetes, less than 1% of those receiving intensive glucose control in the DCCT had significantly impaired vision or kidney failure or needed a limb amputation due to diabetes.

“Tight control is difficult to achieve and maintain, but its benefits have changed the course of diabetes,” says Dr. Saul Genuth of Case Western University, who co-chairs the EDIC study. Major technology improvements in the past decade, such as continuous glucose monitoring devices and improved insulin pump technology, are now helping patients control their blood glucose more precisely and conveniently.

Related Links:
Type 1 Diabetes:

http://health.nih.gov/result.asp?terms=diabetes&disease_id=379

DCCT and EDIC:
http://diabetes.niddk.nih.gov/dm/pubs/control/

Reference:
NIH.gov (2009). Intensive glucose control reduces complications of type 1 diabetes.  Retrieved August 3, 2009, from http://www.nih.gov/news/research_matters/august2009/08032009diabetes.htm