Thursday, August 23, 2012

Pneumonia bug evolves to evade vaccine

This is an old, old news, but if all true, and continuing, it is a cause of alarm: our drugs are no longer effective!

Posted: 30 January 2012

Researcher with blood sample
PARIS, France: Bugs that cause childhood pneumonia and meningitis have evolved to evade vaccines by swapping bits of their genome with other bacteria, according to a study published on Sunday.

The findings, published in Nature Genetics, show how quickly these life-threatening pathogens can disguise themselves with borrowed genetic decoys, and how hard it is for medicine to keep up.

Diseases caused by Streptococcus pneumoniae are thought to kill over a million young children around the world each year.

Vaccines that protect against these so-called pneumoccoccal infections are designed to recognise a material on the outer surface of a bacterium's cell called polysaccharide.

Each of over 90 kinds, or "serotypes", of these bacteria have a different polysaccharide coating.

In 2000, a vaccine that targeted seven serotypes proved highly effective when introduced in the United States. The same formula - which also prevented transmission from children to adults - was adopted in Britain.

Over time, however, the vaccine worked less well, so researchers led by Rory Bowden at the University of Oxford set out to discover why.

Combining cutting-edge genetic analysis with epidemiology, which examines how disease spreads, they found that the deadly pathogens escaped detection by swapping genes with other, slightly different, bacteria.

Remarkably, the exchanged genetic material came from precisely that part of the genome responsible for making the cell's coating - the area targeted by the vaccine.

The bacteria, in other words, had kept their virulence intact but changed their outward appearance.

"Imagine that each strain of the pneumoccoccus bacteria is a class of schoolchildren all wearing the school uniform," explained Bowden.

"If a boy steals from the corner shop, a policeman - the vaccine - can easily identify which school he belongs to by his uniform."

But if the boy swaps his sweater with a friend from another school, Bowden continued, the policeman will no longer know where to look and the thief, like the bacteria, will escape.

The researchers identified several such "recombined" serotypes resistant to the vaccine, and one in particular that had spread across the United States from east to west over several years.

They also observed - for the first time outside a laboratory - that the bugs were able to swap several parts of their respective genomes at once.

"This is of particular concern, as recombination involving multiple fragments of DNA allows rapid and simultaneous exchange of key regions of the genome within the bug, potentially allowing it to quickly develop antibiotic resistance," the researchers said.

In both the United States and Britain, the original vaccine has now been replaced with a new one that targets 13 rather than seven of the telltale serotypes.

But the scientists caution that the bacteria will continue to morph into new forms.

"The current vaccine strategy ... is extremely effective," co-author Bernard Beall, a scientist at the Centres for Disease Control and Prevention in Atlanta, said in a statement.

"However, our observations indicate that the organism will continue to adapt to this strategy with some measurable success."

- AFP/de

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Pneumonia bug evolves to evade vaccine

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S'pore scientists discover cells that cause HPV-related cervical cancers

Man, this is another local news...

Posted: 12 June 2012

Test tubes
SINGAPORE: Scientists in Singapore have discovered a set of cells in the womb that causes human papillomaviruses or HPV-related cervical cancers.

Cervical cancer is the seventh most common female cancer in Singapore and about 200 cases are diagnosed every year.

Infection with HPV is the most common cause or risk factor for cervical cancer.

HPV infection causes a pre-invasive cancer, known as Cervical Intraepithelial Neoplasia, which are pre-cancerous lesions that can progress and potentially become invasive cancer if left untreated.

The team of scientists, from research agency A*A*STAR's Institute of Medical Biology and Genome Institute of Singapore, worked with clinicians from Boston's Brigham and Women's Hospital (BWH) in this study.

They found that a set of cells, located at the cervix, have unique biomarkers that are seen in all forms of invasive cervical cancers linked to HPV. This means that the signature markers of these particular group of cells can provide a way of distinguishing potentially dangerous pre-cancerous lesions from benign ones.

Their research was published in the prestigious journal, Proceedings of the National Academy of Sciences this week.

The team also showed that these cells do not regenerate when excised. It said these findings have immense clinical implications in the diagnosis, prevention and treatment of cervical cancer.

For example, it raises the distinct possibility that removing this set of cells in young women could reduce their risk of cervical cancer.

Dr Christopher P. Crum, Director of Women's and Perinatal Pathology in the Department of pathology at BWH, said: "It has been a decades-old mystery why cervical cancers caused by HPV arise only from a discrete region of the cervix, known as the 'squamocolumnar junction', despite the presence of the virus throughout the genital tract.

"The discovery of these cells finally resolves this mystery and will have wide-ranging impact, from developing more meaningful animal models of early cervical carcinogenesis to clinical implications."

Dr Wa Xian, Principal Investigator at IMB, said: "Our study also revealed that this exotic population of cells does not reappear after ablation by cone biopsy.

"This finding helps to explain the low rate of new HPV infections in the cervix after excisional therapy and also raises the distinct possibility that pre-emptive removal of these cells in young women could reduce their risk of cervical cancer. This could be an alternative to current vaccines which only protect against HPV types 16 and 18."

Added Dr Frank Mckeon, Senior Group Leader at GIS: "Our previous work on esophageal cancer opened up the possibility of 'preventive therapy' to stamp out the disease by eliminating this small group of cells. This recent work in the cervix further validates this concept and raises important possibilities for early intervention to prevent malignancies linked to very small populations of these unusual, discrete population of cells."

In a landmark paper published in Cell in June 2011, Dr Wa and Dr Mckeon identified a novel mechanism for the evolution of highly aggressive cancers in collaboration with BWH and NUS.

They discovered that a discrete population of cells at the junction of the esophagus and stomach were linked to precursors of esophageal cancer (Barrett's metaplasia).

It was the first time scientists realised that some cancers originate from just a small set of cells that are unique from the other cells that reside around them.


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S'pore scientists discover cells that cause HPV-related cervical cancers

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Health woes persist for young cancer survivors: study

Posted: 11 June 2012

A technician in a hospital observing the production of isotopes used in medical diagnosis to locate cancerous cells. (AFP Photo/Francois Guillot)
WASHINGTON: People who survive cancer when they are teenagers or young adults are more likely than their peers who never had cancer to engage in risky behaviors like smoking later on, a US study said on Monday.

They also are more likely to be overweight and have mental health issues and financial problems than their cancer-free counterparts, said the research in the journal Cancer, a peer-reviewed publication of the American Cancer Society.

"There are a lot of factors that play into it," said lead author Eric Tai of the US Centers for Disease Control and Prevention's Division of Cancer.

"Part of it may be that adolescent and young adult cancer survivors are not aware of their medical history and they are not aware of the long-term risks associated with their cancer and their cancer treatment," he told AFP.

"Because of that, they may engage in behaviors not knowing the long-term consequences of them."

Also, people diagnosed with cancer between age 15 and 29 are developmentally very different than older cancer survivors, and so they tend to cope with their illnesses in ways that elders might not, he added.

Finally, they are not being tracked by health care providers as well as younger and older patients.

"There hasn't been very good follow-up of cancer survivors in this group in terms of screening, health checks, those kinds of things looking for early signs of problems that may come up and also looking at risk behaviors."

The data for the study came from a nationwide survey known as the 2009 Behavioral Risk Factor Surveillance System (BRFSS).

Researchers identified people who were diagnosed with cancer when they were adolescents or young adults, and compared their responses to questions about their health to a group of 345,592 cancer-free respondents.

A large majority of the young cancer survivors group was female -- 81 percent -- and the most commonly reported type of cancer was cervical (38 percent) followed by other female reproductive cancers (13 percent) and melanoma (nine percent).

The young survivors were more likely to smoke (26 percent compared to 18 percent in the group that never had cancer) and more of them were obese (31 percent versus 27 percent).

Twice as many reported being disabled (36 percent compared to 18 percent) and 24 percent said they were in poor physical health while just 10 percent of the cancer-free group said the same.

Poor mental health was mentioned by 20 percent of young cancer survivors, twice as many as in the control group, and they were also more likely to forgo medical care because of the cost (24 percent versus 15 percent).

Adolescent and young adult cancer survivors also reported higher rates of heart disease, high-blood pressure, asthma and diabetes.

Many of these problems could be avoided with better follow-up care, Tai said.

"Health care providers really need to be aware of established follow-up guidelines, which includes information on potential latent effects, risk factors, screening and evaluation, counselling, and other interventions."

- AFP/al

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Health woes persist for young cancer survivors: study

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Pneumonia, diarrhea are top killers of kids: UNICEF

Posted: 08 June 2012

Malian refugees with their babies at the UNICEF medical centre in the M'bere refugee camp near Bassiknou in the Nema region of southwestern Mauritania. (AFP Photo/Abdelhak Senna)
UNITED NATIONS: Pneumonia and diarrhea are among the top causes of childhood deaths around the world, particularly among the poor, said a report out Friday by the UN Children's Fund.

UNICEF said that while these two diseases kill more than two million children each year, making up 29 per cent of child deaths under age five worldwide, some simple interventions could save lots of lives in the coming years.

The report urges the 75 countries with the highest mortality rates to aim to treat poor children with diarrhea and pneumonia the same way they do those from the top 20 per cent of households, a so-called "equity approach."

Key interventions include vaccinating against the major causes of pneumonia and diarrhea, encouraging infant breastfeeding, improving access to clean water and sanitation, offering antibiotics for pneumonia and rehydration solutions for diarrhea.

"Modeled estimates suggest that by 2015 more than two million child deaths due to pneumonia and diarrhea could be averted across the 75 countries with the highest mortality burden," said the report.

"If national coverage of key pneumonia and diarrhea interventions were raised to the level in the richest 20 per cent of households in each country," it added.

About half of childhood deaths in the world due to diarrhea or pneumonia take place in five countries: India, Nigeria, Democratic Republic of the Congo, Pakistan and Ethiopia, said the report.

There has been some progress in offering vaccines against Hemophilus influenza type b, as well as pneumococcal conjugate vaccines and rotavirus vaccines in the poorest countries, but more effort is needed, it said.

Water and sanitation is another key hurdle, with 783 million people globally not using an improved drinking water source, and 2.5 billion not using sanitation facilities.

"Nearly 90 per cent of deaths due to diarrhea worldwide have been attributed to unsafe water, inadequate sanitation and poor hygiene," said the report.

"Hand washing with water and soap, in particular, is among the most cost-effective health interventions to reduce the incidence of both childhood pneumonia and diarrhea."

Pneumonia is responsible for 18 per cent of childhood deaths worldwide each year, and diarrhea is linked to 11 per cent.

In contrast, AIDS is responsible for two per cent of global childhood deaths annually and malaria for seven per cent, according to the report.

- AFP/ck

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Pneumonia, diarrhea are top killers of kids: UNICEF

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New drug shows promise against skin cancer

Posted: 07 June 2012

A dermatologist examining a patient for skin cancer. (AFP Photo/Mychele Daniau)
WASHINGTON: A newly approved drug has shown promise in keeping two rare variations of skin cancer at bay, according to research published in the New England Journal of Medicine on Wednesday.

The drug, Erivedge (vismodegib), is made by Genentech, a US subsidiary of the Swiss drug giant Roche, and was approved by the US Food and Drug Administration in January after an expedited review.

It aims to treat basal cell carcinoma, which is the most common form of skin cancer in the world but which is rarely deadly. Basal cell carcinoma accounts for 80 percent of non-melanoma cancers and some two million new cases in the US each year.

The journal published two studies that show how it helped some patients with two unusual variations of basal cell carcinoma: metastatic basal cell carcinoma and Gorlin syndrome, also known as Basal Cell Nevus Syndrome.

There is no other treatment for Gorlin syndrome, which strikes one in 50,000 people and involves the constant growth of tumours, which are often not deadly but can cause scarring and require frequent surgeries.

Subjects with Gorlin syndrome who took vismodegib developed an average of two new tumours per year, compared with 29 new tumours in subjects taking a placebo, the study said.

When it came to people whose basal cell carcinoma had spread, the study showed 30 percent of 33 patients with metastatic basal cell carcinoma responded to treatment, meaning their tumours shrank.

Forty-three percent of 63 subjects with locally advanced basal cell carcinoma responded in kind.

The phase II study showed a median progression-free survival time of 9.5 months, but overall survival rates have not yet been established.

"It is a landmark day for patients with basal cell carcinoma and all those involved in their care -- the greatest advance in therapy yet seen for this disease," said an accompanying editorial by John Lear, consultant dermatologist at Manchester Royal Infirmary in Britain.

However, he pointed out the high rate of adverse effects, including loss of taste, hair loss and muscle cramps, which led to a high rate of people dropping out of the study early.

"Side effects are considerable and frequent, resulting in high rates of drug discontinuation, and these rates will probably be even higher in clinical practice," Lear said.

More study is needed to determine how long the drug may work to ward off cancer, what populations it may best serve, and when it should be optimally administered, he added.

- AFP/al

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New drug shows promise against skin cancer

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