EFSA's Panel on Animal Health and Welfare (AHAW) has published five scientific opinions and a scientific report on the overall effects of the most relevant farming systems on the welfare of dairy cows and related diseases. The Panel concluded that long term genetic selection for higher milk yield and the nature of the farming systems used - i.e. housing and equipment, as well as management and handling practices - are major factors affecting the health and welfare of dairy cows. Lameness and mastitis are the most significant indicators of poor dairy cow welfare, as well as reproductive, metabolic and behavioural disorders. The Panel proposed a series of recommendations which could be taken into account by risk managers in view of further improving welfare in the areas of housing, feeding and the genetic selection of dairy cows.
On request of the European Commission, the AHAW Panel considered, in its first opinions in the area of dairy cow welfare whether current farming and husbandry systems meet the welfare needs of dairy cows. The Panel also evaluated the impact of genetic selection aimed at increasing milk yield on dairy cow welfare in the various farming systems used , and highlighted the correlation between genetic selection and the incidence of lameness, mastitis, reproductive and metabolic disorders.
Over the last thirty years genetic selection for higher milk yield has changed the body shape and increased the size of dairy cows, therefore increasing their requirement for space. Scientific experts highlighted the importance of allocating enough space for cattle movement when designing resting, feeding and walking areas. The Panel recommended that the genetic selection of dairy cows should address their resistance to diseases such as lameness and mastitis, as well as improve their fertility, health and longevity.
Scientific experts took into account all available data in defining levels for light, indoor temperature and relative humidity for good welfare. They recommended that the design of resting, walking and feeding areas in the buildings should allow for sufficient movement and exercise. The Panel also said that while the use of tie-stalls continues, cows should have daily exercise that involves walking freely. On this point, six members of the AHAW Panel expressed a minority opinion highlighting evidence of poor welfare in dairy cattle held in tie-stalls and recommended that dairy cattle should not be routinely kept in tie-stalls
The Panel concluded that achieving reduction of mastitis can be obtained not only from treating the disease and preventing its transmission, but also from improving the animals' immune systems. This can be achieved by minimising stress factors and through controlled and nutritionally-balanced feeding (e.g. by providing the most appropriate type of dietary fibre for the digestive system of dairy cows).
The Panel also concluded that farms with a high prevalence of lameness in dairy cows (e.g. above 10%) do not have an adequate prevention programme and should improve housing conditions, genetic selection and management practices. Moreover, farmers who are well trained in recognising signs of disease at an early stage and in knowing when to seek veterinary advice can contribute to reducing the prevalence of lameness.
Source
EFSA
воскресенье, 15 мая 2011 г.
Prion Filter Could Prevent VCJD Spread From Donated Blood
A filter that takes prions (carriers of vCJD) out of infected blood has been successfully tested on hamsters and UK scientists are optimistic of getting similar results with human donated blood.
The results of this research are reported in The Lancet.
Prions are proteins that cause a range of diseases, including Bovine Spongiform Encephalopathy (BSE, mad cow disease), scrapie (like BSE but occurs in sheep) and variant Creutzfeldt-Jakob Disease (vCJD, the human form of mad cow disease). They latch onto brain tissue and create havoc by making the surrounding brain proteins change their shape, thus interfering with vital functions like message transmission from brain cell to brain cell.
Prion-related diseases can take many years to develop and are difficult to diagnose in the early or dormant stages.
The Cambridge-based scientists have found that a molecule called L13 sticks to prion protein (PrP) in blood that is infected with scrapie. Early tests show it could also stick to prions that cause vCJD in humans.
They processed a batch of hamster blood in two stages, and kept some unprocessed blood. The first stage removed the white blood cells (leucoreduction - a procedure performed on donated human blood before it is banked), and the second stage passed it through a filter using L13.
They also had a batch that was filtered with L13A, a version that is made on a manufactured scale.
They injected the leucoreduced blood into 99 hamsters. 15 of them were infected with scrapie 540 days later.
The L13 and L13A filtered blood was injected into 96 (100 for the L13A) hamsters, none of which became infected with scrapie.
The potential benefits of this process, if proven for humans, lie in the fact that you only need very low concentrations of prions (virtually impossible to detect) to cause vCJD in a recipient. The donor may not have any symptoms for years, making detection very difficult. In such a scenario the only safe option is to clean all donated blood.
However, blood transfusion experts are cautious, saying the results need to be repeated on human blood. Quite how this is to be done is not clear, since there are no precedents and they see many problems, for example how much precious blood might be lost, and how might filtering affect the other properties of human blood?
Restrictions on blood donation because of potential infection by prions were triggered in 2004 when a report in The Lancet suggested that vCJD could be passed from human to human (as opposed to ingesting BSE infected products) via blood transfusion. Fearful of an epidemic, the UK authorities banned anyone who had received a blood transfusion since 1980 from giving blood.
And in 2002 in the US, the Food and Drug Administration (FDA), introduced a ban that stops people who stayed in certain European countries for 6 months or more (3 months in the UK) between 1980 and 1996 from giving blood. Australia has a similar policy, as does Canada.
"Reduction in infectivity of endogenous transmissible spongiform encephalopathies present in blood by adsorption to selective affinity resins."
Luisa Gregori PhD, Patrick V Gurgel PhD, Julia T Lathrop PhD, Peter Edwardson PhD, Brian C Lambert, Prof Ruben G Carbonell PhD, Steven J Burton PhD, David J Hammond PhD and Dr Robert G Rohwer PhD.
The Lancet 2006; 368:2226-2230
DOI:10.1016/S0140-6736(06)69897-8
Click here for abstract.
The results of this research are reported in The Lancet.
Prions are proteins that cause a range of diseases, including Bovine Spongiform Encephalopathy (BSE, mad cow disease), scrapie (like BSE but occurs in sheep) and variant Creutzfeldt-Jakob Disease (vCJD, the human form of mad cow disease). They latch onto brain tissue and create havoc by making the surrounding brain proteins change their shape, thus interfering with vital functions like message transmission from brain cell to brain cell.
Prion-related diseases can take many years to develop and are difficult to diagnose in the early or dormant stages.
The Cambridge-based scientists have found that a molecule called L13 sticks to prion protein (PrP) in blood that is infected with scrapie. Early tests show it could also stick to prions that cause vCJD in humans.
They processed a batch of hamster blood in two stages, and kept some unprocessed blood. The first stage removed the white blood cells (leucoreduction - a procedure performed on donated human blood before it is banked), and the second stage passed it through a filter using L13.
They also had a batch that was filtered with L13A, a version that is made on a manufactured scale.
They injected the leucoreduced blood into 99 hamsters. 15 of them were infected with scrapie 540 days later.
The L13 and L13A filtered blood was injected into 96 (100 for the L13A) hamsters, none of which became infected with scrapie.
The potential benefits of this process, if proven for humans, lie in the fact that you only need very low concentrations of prions (virtually impossible to detect) to cause vCJD in a recipient. The donor may not have any symptoms for years, making detection very difficult. In such a scenario the only safe option is to clean all donated blood.
However, blood transfusion experts are cautious, saying the results need to be repeated on human blood. Quite how this is to be done is not clear, since there are no precedents and they see many problems, for example how much precious blood might be lost, and how might filtering affect the other properties of human blood?
Restrictions on blood donation because of potential infection by prions were triggered in 2004 when a report in The Lancet suggested that vCJD could be passed from human to human (as opposed to ingesting BSE infected products) via blood transfusion. Fearful of an epidemic, the UK authorities banned anyone who had received a blood transfusion since 1980 from giving blood.
And in 2002 in the US, the Food and Drug Administration (FDA), introduced a ban that stops people who stayed in certain European countries for 6 months or more (3 months in the UK) between 1980 and 1996 from giving blood. Australia has a similar policy, as does Canada.
"Reduction in infectivity of endogenous transmissible spongiform encephalopathies present in blood by adsorption to selective affinity resins."
Luisa Gregori PhD, Patrick V Gurgel PhD, Julia T Lathrop PhD, Peter Edwardson PhD, Brian C Lambert, Prof Ruben G Carbonell PhD, Steven J Burton PhD, David J Hammond PhD and Dr Robert G Rohwer PhD.
The Lancet 2006; 368:2226-2230
DOI:10.1016/S0140-6736(06)69897-8
Click here for abstract.
USA - some quarantined cows could be killed
At least some cows from two Washington state herds quarantined since discovery of a Holstein with mad cow disease will have to be killed, some who may have been exposed to the infection and others because of public fear.
A decision on the first cows to be euthanized will be made very soon, Dr. Ron DeHaven, the Agriculture Department's chief veterinarian, said Friday.
'It would be safe to assume that ... some or all of those animals will need to be sacrificed,' DeHaven said of the two Washington state herds.
Two of the quarantined herds contain calves of the infected Holstein, and mother-to-calf transmission is considered unlikely but can't be ruled out.
One of the calves lives in the mother's own herd in Mabton, Washington, home also to nine other cows that entered the United States from Canada along with the infected Holstein.
The infected mother was born before August 1997, when cow parts were prohibited from cattle feed, the main way that mad cow disease is thought to spread through livestock -- and thus the chief suspect in how she became infected. The question now is how many other cows in that Mabton herd would have eaten pre-1997 feed, too, and thus need to be sacrificed.
But other cows may ultimately be sacrificed, too, DeHaven said.
'Even though we know with a very good degree of certainty that there's no direct disease spread animal to animal, simply being on the same farm there are some public perception issues related to those animals,' he said.
Mad cow disease is a concern because humans can develop a brain-wasting illness, variant Creutzfeldt-Jakob disease, from consuming contaminated beef products. Although 153 people worldwide have contracted that illness, most in Britain, it has never been diagnosed in an American.
A total of 81 animals were believed shipped across the border with the Holstein from Canada in 2001, and USDA has accounted for 11 of them. One is at a dairy farm in Mattawa, Washington, which recently was quarantined, the third herd to be contained.
A decision on the first cows to be euthanized will be made very soon, Dr. Ron DeHaven, the Agriculture Department's chief veterinarian, said Friday.
'It would be safe to assume that ... some or all of those animals will need to be sacrificed,' DeHaven said of the two Washington state herds.
Two of the quarantined herds contain calves of the infected Holstein, and mother-to-calf transmission is considered unlikely but can't be ruled out.
One of the calves lives in the mother's own herd in Mabton, Washington, home also to nine other cows that entered the United States from Canada along with the infected Holstein.
The infected mother was born before August 1997, when cow parts were prohibited from cattle feed, the main way that mad cow disease is thought to spread through livestock -- and thus the chief suspect in how she became infected. The question now is how many other cows in that Mabton herd would have eaten pre-1997 feed, too, and thus need to be sacrificed.
But other cows may ultimately be sacrificed, too, DeHaven said.
'Even though we know with a very good degree of certainty that there's no direct disease spread animal to animal, simply being on the same farm there are some public perception issues related to those animals,' he said.
Mad cow disease is a concern because humans can develop a brain-wasting illness, variant Creutzfeldt-Jakob disease, from consuming contaminated beef products. Although 153 people worldwide have contracted that illness, most in Britain, it has never been diagnosed in an American.
A total of 81 animals were believed shipped across the border with the Holstein from Canada in 2001, and USDA has accounted for 11 of them. One is at a dairy farm in Mattawa, Washington, which recently was quarantined, the third herd to be contained.
Seeking The Cause Of Mad Cow Disease
The cause of diseases such as BSE in cattle and Creutzfeld-Jakob disease in humans is a prion protein. This protein attaches to cell membranes by way of an anchor made of sugar and lipid components (a glycosylphosphatidylinositol, GPI) anchor. The anchoring of the prions seems to have a strong influence on the transformation of the normal form of the protein into its pathogenic form, which causes scrapie and mad cow disease. A team headed by Christian F. W. Becker at the TU Munich and Peter H. Seeberger at the ETH Zurich has now "recreated" the first GPI-anchored prion in the laboratory. As they report in the journal Angewandte Chemie, they have been able to develop a new general method for the synthesis of anchored proteins.
The isolation of a complete prion protein that includes the anchor has not yet been achieved, nor has it been possible to produce a synthetic GPI-anchored protein. The function of the GPI anchor has thus remained in the dark. A new synthetic technique has now provided an important breakthrough for the German and Swiss team of researchers.
The sugar component of natural prion GPI anchors consists of five sugar building blocks, to which further sugars are attached through branches. Details of the lipid component have not been determined before. As a synthetic target, the researchers thus chose a construct made of the five sugars and one C18-lipid chain and worked out the corresponding synthetic route. First, the anchor was furnished with the sulfur-containing amino acid cysteine. The prion protein was produced with the use of bacteria and was given an additional thioester (a sulfur-containing group). The centerpiece of the new concept is the linkage of the protein and anchor by means of a native chemical ligation, in which the cysteine group reacts with the thioester. This allowed the prion protein to firmly attach to the vesicle membranes by way of the artificial anchor.
This new concept will allow production of sufficient quantities of proteins modified with GPI anchors for in-depth studies. Experiments with the artificial GPI prion protein should help to clarify the influence of membrane association on conversion of the protein into the pathogenic scrapie form. This should finally make it possible to track down the infectious form of the prion.
This release is available in German.
Author: Christian F. W. Becker, Max-Planck-Institut f??r molekulare Physiologie, Dortmund (Germany), ch.tum.de/proteinchemie/
Title: Semisynthesis of a Glycosylphosphatidylinositol-Anchored Prion Protein
Angewandte Chemie International Edition 2008, 47, No. 43, 8215-8219, doi: 10.1002/anie.200802161
The isolation of a complete prion protein that includes the anchor has not yet been achieved, nor has it been possible to produce a synthetic GPI-anchored protein. The function of the GPI anchor has thus remained in the dark. A new synthetic technique has now provided an important breakthrough for the German and Swiss team of researchers.
The sugar component of natural prion GPI anchors consists of five sugar building blocks, to which further sugars are attached through branches. Details of the lipid component have not been determined before. As a synthetic target, the researchers thus chose a construct made of the five sugars and one C18-lipid chain and worked out the corresponding synthetic route. First, the anchor was furnished with the sulfur-containing amino acid cysteine. The prion protein was produced with the use of bacteria and was given an additional thioester (a sulfur-containing group). The centerpiece of the new concept is the linkage of the protein and anchor by means of a native chemical ligation, in which the cysteine group reacts with the thioester. This allowed the prion protein to firmly attach to the vesicle membranes by way of the artificial anchor.
This new concept will allow production of sufficient quantities of proteins modified with GPI anchors for in-depth studies. Experiments with the artificial GPI prion protein should help to clarify the influence of membrane association on conversion of the protein into the pathogenic scrapie form. This should finally make it possible to track down the infectious form of the prion.
This release is available in German.
Author: Christian F. W. Becker, Max-Planck-Institut f??r molekulare Physiologie, Dortmund (Germany), ch.tum.de/proteinchemie/
Title: Semisynthesis of a Glycosylphosphatidylinositol-Anchored Prion Protein
Angewandte Chemie International Edition 2008, 47, No. 43, 8215-8219, doi: 10.1002/anie.200802161
Active vaccine prevents mice from developing prion disease
NYU School of Medicine scientists have created the first active vaccine that can significantly delay and possibly prevent
the onset of a brain disease in mice that is similar to mad cow disease. The new findings, published online this week in the
journal Neuroscience, could provide a platform for the development of a vaccine to prevent a group of fatal brain diseases
caused by unusual infectious particles called prions.
Although no cure for these diseases -- which include scrapie, mad cow disease, and chronic wasting disease -- is on the
horizon, many research groups in both the United States and Europe are working on prion vaccines. But the NYU study is
important because it breaks new ground in demonstrating that active immunization can protect a significant percentage of
animals from developing symptoms of prion disease, explains Thomas Wisniewski, M.D., Professor of Neurology, Pathology, and
Psychiatry, and the lead author of the study.
The vaccines that provide active immunization are made, in part, from proteins found on disease-causing organisms. In
response to these proteins, the animal's immune system produces antibodies that will destroy them any time they appear in the
body. Most vaccines in use today provide such active immunization.
The prion vaccine developed at NYU would most likely first be used to protect livestock, since most prion infections occur in
animals and are thought to be transmitted orally, explains Dr. Wisniewski. The version of prion disease that affects humans
usually occurs spontaneously, and only rarely as a result of eating contaminated meat.
"The potential use for a prion vaccine in humans is still theoretical," says Dr. Wisniewski. "But if, for example, there is
ever a more significant outbreak of chronic wasting disease and if this disease were found to be transmissible to humans,
then we would need a vaccine like this to protect people in hunting areas."
Currently, an outbreak of chronic wasting disease is occurring in some Western states, and the disease's geographic range is
expanding. Two cases in wild deer have recently been reported for the first time in New York State, according to the New York
State Department of Environmental Conservation.
First mucosal prion vaccine
The NYU study is also the first to use a mucosal prion vaccine, given by mouth rather than through the skin, which localizes
the initial immune response to the gut and mainly stimulates an antibody response, says Dr. Wisniewski. "By giving our
vaccine orally, we're stimulating an immune response mainly in the digestive tract," he explains. "Thus, harmful prions in
contaminated food will be destroyed in the gut and will not reach other organs in the body." Because the research was
conducted in normal mice, the NYU researchers say it will be easier to apply in animals in the wild, which are at risk for
developing prion disease.
Prion disease is contracted when an animal eats the body parts of other animals contaminated with prions. What makes these
infectious particles unusual is that they are proteins that have the same amino acid composition as equivalent proteins
occurring naturally in the body. But the prions turn deadly by changing shape. These "misfolded" proteins tend to aggregate
in toxic, cell-killing clumps. As an infection takes hold, prion proteins invade brain tissue and force normal proteins to
adopt their configuration. In time, the diseased animal develops dementia, loses control of its limbs, and eventually dies.
There are no treatments for prion-related diseases, and prions can easily infect the body because they do not elicit any
immune response.
To create a vaccine that could rally the immune system of mice, the NYU researchers designed a vaccine in which scrapie
prions were attached to a genetically modified strain of Salmonella. This bacterium is also used in several animal vaccines
and in human vaccines for cholera and typhoid fever. Among mice vaccinated prior to prion exposure, approximately 30%
remained alive and symptom-free for 500 days, according to the study. By comparison, mice that didn't receive the vaccine
survived only an average of 185 days, and all were dead by 300 days.
The NYU scientists are in the process of redesigning the vaccine for deer and cattle. After choosing the appropriate bacteria
for each vaccine, they must genetically modify it to carry the prion protein. "These technical issues are not major hurdles,"
says Dr. Wisniewski. "Developing a marketable vaccine for livestock is something that is very achievable."
The authors of the new study are: Fernando Go?i, Elin Knudsen, Henrieta Scholtzova, Joanna Pankiewicz, Einar M. Sigurdsson,
and Thomas Wisniewski of the NYU School of Medicine; Fernanda Schreiber and Jose Alejandro Chabalgoity of the University of
Uruguay; Richard Carp and Harry C. Meeker of the New York State Institute for Basic Research in Developmental Disabilities,
New York City; David R. Brown of the University of Bath, United Kingdom; and Man-Sun Sy of Case Western Reserve University
School of Medicine, Cleveland, Ohio.
Contact: Pamela Mcdonnell
pamela.mcdonnellnyumc
212-404-3555
New York University Medical Center and School of Medicine
med.nyu
the onset of a brain disease in mice that is similar to mad cow disease. The new findings, published online this week in the
journal Neuroscience, could provide a platform for the development of a vaccine to prevent a group of fatal brain diseases
caused by unusual infectious particles called prions.
Although no cure for these diseases -- which include scrapie, mad cow disease, and chronic wasting disease -- is on the
horizon, many research groups in both the United States and Europe are working on prion vaccines. But the NYU study is
important because it breaks new ground in demonstrating that active immunization can protect a significant percentage of
animals from developing symptoms of prion disease, explains Thomas Wisniewski, M.D., Professor of Neurology, Pathology, and
Psychiatry, and the lead author of the study.
The vaccines that provide active immunization are made, in part, from proteins found on disease-causing organisms. In
response to these proteins, the animal's immune system produces antibodies that will destroy them any time they appear in the
body. Most vaccines in use today provide such active immunization.
The prion vaccine developed at NYU would most likely first be used to protect livestock, since most prion infections occur in
animals and are thought to be transmitted orally, explains Dr. Wisniewski. The version of prion disease that affects humans
usually occurs spontaneously, and only rarely as a result of eating contaminated meat.
"The potential use for a prion vaccine in humans is still theoretical," says Dr. Wisniewski. "But if, for example, there is
ever a more significant outbreak of chronic wasting disease and if this disease were found to be transmissible to humans,
then we would need a vaccine like this to protect people in hunting areas."
Currently, an outbreak of chronic wasting disease is occurring in some Western states, and the disease's geographic range is
expanding. Two cases in wild deer have recently been reported for the first time in New York State, according to the New York
State Department of Environmental Conservation.
First mucosal prion vaccine
The NYU study is also the first to use a mucosal prion vaccine, given by mouth rather than through the skin, which localizes
the initial immune response to the gut and mainly stimulates an antibody response, says Dr. Wisniewski. "By giving our
vaccine orally, we're stimulating an immune response mainly in the digestive tract," he explains. "Thus, harmful prions in
contaminated food will be destroyed in the gut and will not reach other organs in the body." Because the research was
conducted in normal mice, the NYU researchers say it will be easier to apply in animals in the wild, which are at risk for
developing prion disease.
Prion disease is contracted when an animal eats the body parts of other animals contaminated with prions. What makes these
infectious particles unusual is that they are proteins that have the same amino acid composition as equivalent proteins
occurring naturally in the body. But the prions turn deadly by changing shape. These "misfolded" proteins tend to aggregate
in toxic, cell-killing clumps. As an infection takes hold, prion proteins invade brain tissue and force normal proteins to
adopt their configuration. In time, the diseased animal develops dementia, loses control of its limbs, and eventually dies.
There are no treatments for prion-related diseases, and prions can easily infect the body because they do not elicit any
immune response.
To create a vaccine that could rally the immune system of mice, the NYU researchers designed a vaccine in which scrapie
prions were attached to a genetically modified strain of Salmonella. This bacterium is also used in several animal vaccines
and in human vaccines for cholera and typhoid fever. Among mice vaccinated prior to prion exposure, approximately 30%
remained alive and symptom-free for 500 days, according to the study. By comparison, mice that didn't receive the vaccine
survived only an average of 185 days, and all were dead by 300 days.
The NYU scientists are in the process of redesigning the vaccine for deer and cattle. After choosing the appropriate bacteria
for each vaccine, they must genetically modify it to carry the prion protein. "These technical issues are not major hurdles,"
says Dr. Wisniewski. "Developing a marketable vaccine for livestock is something that is very achievable."
The authors of the new study are: Fernando Go?i, Elin Knudsen, Henrieta Scholtzova, Joanna Pankiewicz, Einar M. Sigurdsson,
and Thomas Wisniewski of the NYU School of Medicine; Fernanda Schreiber and Jose Alejandro Chabalgoity of the University of
Uruguay; Richard Carp and Harry C. Meeker of the New York State Institute for Basic Research in Developmental Disabilities,
New York City; David R. Brown of the University of Bath, United Kingdom; and Man-Sun Sy of Case Western Reserve University
School of Medicine, Cleveland, Ohio.
Contact: Pamela Mcdonnell
pamela.mcdonnellnyumc
212-404-3555
New York University Medical Center and School of Medicine
med.nyu
FDA Proposes Barring Certain Cattle Material From Medical Products As BSE Safeguard
The U.S. Food and Drug Administration is proposing to limit the materials used in some medical products in order to keep them free of the agent thought to cause mad cow disease, also known as bovine spongiform encephalopathy or BSE.
This is the latest in a series of BSE safeguards that would bar material that has been found to harbor the highest concentrations of this fatal agent in infected cattle. These materials would be prohibited from use as ingredients in medical products or elements of product manufacturing.
The proposed rule would cover drugs (prescription, over-the-counter, and homeopathic), biologics (such as vaccines) and medical devices intended for use in humans as well as drugs intended for use in ruminant animals like cattle and sheep. Cattle can get mad cow disease, while sheep can get a similar disease known as scrapie.
"These measures build on a series of barriers FDA and the U.S. Department of Agriculture have erected to further protect humans from exposure to the fatal agent linked to BSE," said Andrew von Eschenbach, M.D., Commissioner Food and Drugs. "This proposed rule adds one more safeguard that will reduce the risk of transmission even further."
The cattle materials prohibited in the proposed rule are those that pose the highest risk of containing infectious material and include:
-- the brain, skull, eyes and spinal cords from cattle 30 months and older;
-- the tonsils and a portion of the small intestines from all cattle regardless of their age or health;
-- any material from "downer" cattle--those that cannot walk;
-- any material from cattle not inspected and passed for human consumption;
-- fetal calf serum if appropriate procedures have not been followed to prevent its contamination with materials prohibited by this proposed rule;
-- tallow that contains more than 0.15 percent insoluble impurities if the tallow is derived from materials prohibited by this proposed rule and;
-- mechanically separated beef.
To ensure that companies comply with these prohibitions, FDA proposes to require that records be kept to demonstrate that any cattle material used as an ingredient in these medical products or as part of their manufacturing process meet the rule's requirements.
Since 1996, strong evidence has accumulated for a causal relationship between ongoing outbreaks of mad cow disease in Europe and a disease in humans called variant Creutzfeldt-Jakob (vCJD) disease. Both disorders, which are thought to be caused by an unconventional transmissible agent, are invariably fatal brain diseases with incubation periods typically measured in years. Transmission of the BSE agent to humans, leading to vCJD, is believed to occur via ingestion of cattle products contaminated with the BSE agent; however the specific products associated with this transmission are unknown.
About 200 cases of vCJD have been identified worldwide, including three cases in the U.S. However, there is no evidence that those three patients contracted the BSE agent in the U.S.
FDA and USDA's efforts to help protect the public from vCJD have included several other significant steps such as the FDA's 1997 ruminant feed regulation, which forbids the use of certain mammalian-origin proteins in ruminant feed. Also, a 2005 interim final rule bans the use of certain high-risk cattle material in food, dietary supplements and cosmetics.
fda
This is the latest in a series of BSE safeguards that would bar material that has been found to harbor the highest concentrations of this fatal agent in infected cattle. These materials would be prohibited from use as ingredients in medical products or elements of product manufacturing.
The proposed rule would cover drugs (prescription, over-the-counter, and homeopathic), biologics (such as vaccines) and medical devices intended for use in humans as well as drugs intended for use in ruminant animals like cattle and sheep. Cattle can get mad cow disease, while sheep can get a similar disease known as scrapie.
"These measures build on a series of barriers FDA and the U.S. Department of Agriculture have erected to further protect humans from exposure to the fatal agent linked to BSE," said Andrew von Eschenbach, M.D., Commissioner Food and Drugs. "This proposed rule adds one more safeguard that will reduce the risk of transmission even further."
The cattle materials prohibited in the proposed rule are those that pose the highest risk of containing infectious material and include:
-- the brain, skull, eyes and spinal cords from cattle 30 months and older;
-- the tonsils and a portion of the small intestines from all cattle regardless of their age or health;
-- any material from "downer" cattle--those that cannot walk;
-- any material from cattle not inspected and passed for human consumption;
-- fetal calf serum if appropriate procedures have not been followed to prevent its contamination with materials prohibited by this proposed rule;
-- tallow that contains more than 0.15 percent insoluble impurities if the tallow is derived from materials prohibited by this proposed rule and;
-- mechanically separated beef.
To ensure that companies comply with these prohibitions, FDA proposes to require that records be kept to demonstrate that any cattle material used as an ingredient in these medical products or as part of their manufacturing process meet the rule's requirements.
Since 1996, strong evidence has accumulated for a causal relationship between ongoing outbreaks of mad cow disease in Europe and a disease in humans called variant Creutzfeldt-Jakob (vCJD) disease. Both disorders, which are thought to be caused by an unconventional transmissible agent, are invariably fatal brain diseases with incubation periods typically measured in years. Transmission of the BSE agent to humans, leading to vCJD, is believed to occur via ingestion of cattle products contaminated with the BSE agent; however the specific products associated with this transmission are unknown.
About 200 cases of vCJD have been identified worldwide, including three cases in the U.S. However, there is no evidence that those three patients contracted the BSE agent in the U.S.
FDA and USDA's efforts to help protect the public from vCJD have included several other significant steps such as the FDA's 1997 ruminant feed regulation, which forbids the use of certain mammalian-origin proteins in ruminant feed. Also, a 2005 interim final rule bans the use of certain high-risk cattle material in food, dietary supplements and cosmetics.
fda
Infectious Prions Can Arise Spontaneously In Normal Brain Tissue
In a startling new study that involved research on both sides of the Atlantic, scientists from The Scripps Research Institute in Florida and the University College London (UCL) Institute of Neurology in England have shown for the first time that abnormal prions, bits of infectious protein devoid of DNA or RNA that can cause fatal neurodegenerative disease, can suddenly erupt from healthy brain tissue.
The catalyst in the study was the metallic surface of simple steel wires. Previous research showed that prions bind readily to these types of surfaces and can initiate infection with remarkable efficiency. Surprisingly, according to the new research, wires coated with uninfected brain homogenate could also initiate prion disease in cell culture, which was transmissible to mice.
The findings are being published the week of July 26, 2010, in an advance, online edition of the journal Proceedings of the National Academy of Sciences (PNAS).
"Prion diseases such as sporadic Creutzfeldt-Jakob disease in humans or atypical bovine spongiform encephalopathy, a form of mad cow disease, occur rarely and at random," said Charles Weissmann, M.D., Ph.D., chair of Scripps Florida's Department of Infectology, who led the study with John Collinge, head of the Department of Neurodegenerative Disease at UCL Institute of Neurology. "It has been proposed that these events reflect rare, spontaneous formation of prions in brain. Our study offers experimental proof that prions can in fact originate spontaneously, and shows that this event is promoted by contact with steel surfaces."
Infectious prions, which are composed solely of protein, are classified by distinct strains, originally characterized by their incubation time and the disease they cause. These toxic prions have the ability to reproduce, despite the fact that they contain no nucleic acid genome.
Mammalian cells normally produce harmless cellular prion protein (PrPC). Following prion infection, the abnormal or misfolded prion protein (PrPSc) converts PrPC into a likeness of itself, by causing it to change its conformation or shape. The end-stage consists of large aggregates of these misfolded proteins, which cause massive tissue and cell damage.
A Highly Sensitive Test
In the new study, the scientists used the Scrapie Cell Assay, a test originally created by Weissmann that is highly sensitive to minute quantities of prions.
Using the Scrapie Cell Assay to measure infectivity of prion-coated wires, the team observed several unexpected instances of infectious prions in control groups where metal wires had been exposed only to uninfected normal mouse brain tissue. In the current study, this phenomenon was investigated in rigorous and exhaustive control experiments specifically designed to exclude prion contamination. Weissmann and his colleagues in London found that when normal prion protein is coated onto steel wires and brought into contact with cultured cells, a small but significant proportion of the coated wires cause prion infection of the cells - and when transferred to mice, they continue to spawn the disease.
Weissmann noted that an alternative interpretation of the results is that infectious prions are naturally present in the brain at levels not detectable by conventional methods, and are normally destroyed at the same rate they are created. If that is the case, he noted, metal surfaces could be acting to concentrate the infectious prions to the extent that they became quantifiable by the team's testing methods.
The first author of the study, "Spontaneous Generation of Mammalian Prions," is Julie Edgeworth of the UCL Institute of Neurology. Other authors of the study include Nathalie Gros, Jack Alden, Susan Joiner, Jonathan D.F. Wadsworth, Jackie Linehan, Sebastian Brandner, and Graham S. Jackson, also of the UCL Institute of Neurology.
The study was supported by the U.K. Medical Research Council.
The catalyst in the study was the metallic surface of simple steel wires. Previous research showed that prions bind readily to these types of surfaces and can initiate infection with remarkable efficiency. Surprisingly, according to the new research, wires coated with uninfected brain homogenate could also initiate prion disease in cell culture, which was transmissible to mice.
The findings are being published the week of July 26, 2010, in an advance, online edition of the journal Proceedings of the National Academy of Sciences (PNAS).
"Prion diseases such as sporadic Creutzfeldt-Jakob disease in humans or atypical bovine spongiform encephalopathy, a form of mad cow disease, occur rarely and at random," said Charles Weissmann, M.D., Ph.D., chair of Scripps Florida's Department of Infectology, who led the study with John Collinge, head of the Department of Neurodegenerative Disease at UCL Institute of Neurology. "It has been proposed that these events reflect rare, spontaneous formation of prions in brain. Our study offers experimental proof that prions can in fact originate spontaneously, and shows that this event is promoted by contact with steel surfaces."
Infectious prions, which are composed solely of protein, are classified by distinct strains, originally characterized by their incubation time and the disease they cause. These toxic prions have the ability to reproduce, despite the fact that they contain no nucleic acid genome.
Mammalian cells normally produce harmless cellular prion protein (PrPC). Following prion infection, the abnormal or misfolded prion protein (PrPSc) converts PrPC into a likeness of itself, by causing it to change its conformation or shape. The end-stage consists of large aggregates of these misfolded proteins, which cause massive tissue and cell damage.
A Highly Sensitive Test
In the new study, the scientists used the Scrapie Cell Assay, a test originally created by Weissmann that is highly sensitive to minute quantities of prions.
Using the Scrapie Cell Assay to measure infectivity of prion-coated wires, the team observed several unexpected instances of infectious prions in control groups where metal wires had been exposed only to uninfected normal mouse brain tissue. In the current study, this phenomenon was investigated in rigorous and exhaustive control experiments specifically designed to exclude prion contamination. Weissmann and his colleagues in London found that when normal prion protein is coated onto steel wires and brought into contact with cultured cells, a small but significant proportion of the coated wires cause prion infection of the cells - and when transferred to mice, they continue to spawn the disease.
Weissmann noted that an alternative interpretation of the results is that infectious prions are naturally present in the brain at levels not detectable by conventional methods, and are normally destroyed at the same rate they are created. If that is the case, he noted, metal surfaces could be acting to concentrate the infectious prions to the extent that they became quantifiable by the team's testing methods.
The first author of the study, "Spontaneous Generation of Mammalian Prions," is Julie Edgeworth of the UCL Institute of Neurology. Other authors of the study include Nathalie Gros, Jack Alden, Susan Joiner, Jonathan D.F. Wadsworth, Jackie Linehan, Sebastian Brandner, and Graham S. Jackson, also of the UCL Institute of Neurology.
The study was supported by the U.K. Medical Research Council.
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