Dental implants are frequently used as a replacement for missing teeth in order to restore the patient's tooth function and appearance. Previous research demonstrates that the placement of a dental implant disrupts the host tissue in the area of the implant, so practitioners often focus their treatment planning to carefully maintain the patient's bone and gum tissue surrounding the implant. A recent study published in the Journal of Periodontology found that the majority of bone remodeling occurred in the time between the implant placement and final prosthesis placement.

Subsequently, little mean bone change was observed in the five years following the implant placement, independent of type of restoration or implant length. The study, conducted at the University of Texas Health Science Center at San Antonio, evaluated 596 dental implants placed in 192 patients over the age of 18. Patients were screened for adequate oral hygiene and bone volume. Exclusion criteria included heavy smoking, chewing tobacco use, drug abuse, and untreated periodontal disease, amongst others.

Iron chelating drugs have been heavily promoted for use in patients with primary myelofibrosis (PMF), a form of blood cancer often treated with blood transfusion. These drugs, however, which withhold available iron in the body, are highly expensive and potentially toxic. A new study published in American Journal of Hematology finds that their increased use has been propagated by non-evidence based, and often industry-sponsored, statements and opinions, rather than original research, and that the conclusions are often based on poor data.

The study shows that the degree of anemia in patients suffering from PMF, age and need for red blood cell transfusion at diagnosis were stronger predictors for patient survival than serum ferritin level (a protein that stores iron), which is often used as a proxy for iron overload in the blood.

"Although iron chelation therapy in PMF would probably lower serum ferritin level in such patients, its value in terms of meaningful health outcomes remains dubious," says Dr. Ayalew Tefferi of the Mayo Clinic, principle author of the study.

In a related editorial in the journal, Dr. Thomas G. DeLoughery of Oregon Health & Science University states that "hematologists are under increasing pressure to prescribe iron chelation for seemingly any patient being transfused. However, there is no evidence that iron overload affects survival or morbidity."

The findings should impact clinical practice by discouraging the indiscriminate use of an expensive, potentially toxic and unproven therapy. The future challenge in treating myelofibrosis is to avoid transfusions by better therapies to reverse the stem cell defect. "Unfortunately, the recent focus on iron overload as a priority and not the stem cell defect is leading to a misallocation of resources on both the patient and practitioner's part," says DeLoughery.

A recently completed international multi-center clinical trial has found that acyclovir, a drug widely used as a safe and effective treatment to suppress herpes simplex virus-2 (HSV-2), which is the most common cause of genital herpes, does not reduce the risk of HIV transmission when taken by people infected with both HIV and HSV-2.

The majority of people with HIV infection also have HSV-2 infection. Multiple studies have shown that frequent genital herpes recurrences increase the amount of HIV in the blood and genital tract. The HIV virus is also shed from genital herpes ulcers and individuals with such ulcers transmit HIV to others more efficiently. Five preliminary studies showed that it is possible to decrease the amount of HIV in the blood and genital tract through treatment to suppress HSV-2, but these studies did not measure whether this translated into a reduction in HIV transmission. Researchers had hoped that acyclovir's ability to suppress the herpes virus, which causes symptomatic genital sores and breaks in the skin but also frequently is active without symptoms, could reduce the likelihood of sexual transmission of HIV from a person with HIV and HSV-2. The study being reported today is the first to determine whether twice daily use of acyclovir by individuals who are infected with both HSV-2 and HIV reduced the transmission of HIV to their sexual partners.

Led by the University of Washington in Seattle and funded by the Bill & Melinda Gates Foundation, the Partners in Prevention HSV/HIV Transmission Study was conducted among 3,408 African HIV discordant couples, in which one partner had HIV and the other did not. In all the couples, the partner who had HIV also had HSV-2 infection. The study took place at 14 sites in seven countries in eastern and southern Africa (Botswana, Kenya, Rwanda, South Africa, Tanzania, Uganda and Zambia). In sub-Saharan Africa, the majority of new HIV infections occur among heterosexual HIV discordant couples, many of whom are in stable partnerships and unaware that one partner has HIV and the other does not. Genital herpes is thought to be a factor in a substantial proportion of new HIV infections in Africa.

In the primary analysis of HIV transmissions determined by laboratory testing to have occurred within the couple and not acquired from an outside partner, there were 41 infections in the acyclovir arm and 43 in the placebo arm - not a significant difference. Acyclovir suppressive treatment reduced the frequency of genital ulcers by 73% and the average amount of HIV in the blood (by 0.25 log10 copies/milliliter, a reduction of 40%), compared to the placebo arm.

"The Partners in Prevention Study is a direct assessment of the impact of herpes suppression on HIV transmission," explained Dr. Connie Celum, the leader of the study and a UW professor of Global Health and Medicine in the Division of Allergy and Infectious Diseases. "A clinical trial of genital herpes suppression in HIV discordant couples is the most direct way to see if we can make a person less infectious and less likely to transmit HIV to their partner. The study did find that acyclovir significantly reduced genital ulcers due to HSV-2 and modestly reduced HIV levels in the blood, consistent with what the preliminary studies of HSV-2 suppressive treatment had shown. However, it appears that these effects were not sufficient to reduce the risk of HIV transmission."

The study also determined whether acyclovir can slow HIV disease progression among individuals with HIV and HSV-2 who also have CD4 T-cell counts that are too high for HIV antiretroviral treatment under current national guidelines. Specifically, the investigators studied the number of participants in the acyclovir and placebo arms whose CD4 T-cell counts declined to below 200, who started HIV medications, or who died. In this analysis, HIV disease progression was slowed by 17% by acyclovir, an effect that was statistically significant. Given that low-cost, safe ways to delay progression of HIV disease are needed for individuals who are not yet taking HIV medications, this result is encouraging, but the modest effect observed in this study may not be sufficient to promote use of this dose of acyclovir for slowing HIV disease.

"Although the primary outcome of reducing HIV transmission was not observed, the study yielded important information that will inform HIV prevention research in a number of ways," Celum said. "Most importantly, we have demonstrated that interventions must achieve a bigger reduction in HIV levels in order to reduce HIV transmission, especially among persons with high HIV levels. This was an ambitious study, which required testing of an estimated 50,000 couples of unknown HIV status in Africa to recruit the 3,408 HIV discordant couples who volunteered to enroll in the study. This was an important and courageous study to undertake, and I applaud our collaborators at the University of Washington, the investigators and study teams in Africa, the study participants, and the communities where the study was done, for their dedication over the past five years. The findings will bear fruit for both the HIV prevention and the vaccine fields for years to come."

HSV-2 is one of the most common sexually transmitted infections worldwide and is especially prevalent in areas with high rates of HIV infection, with up to 90% of individuals who have HIV also being infected with HSV-2. Most people who are infected with HSV-2 do not know they have the virus because symptoms can be mild or absent. HSV-2 infection can cause recurrent sores and breaks in the skin of the genital region, which can be mild and often go unnoticed. HSV-2 infection also attracts immune cells called CD4 T-cells to the genital region, which HIV uses to establish or pass infection.

The Partners in Prevention HSV/HIV Transmission Study is the first clinical trial to directly test whether suppressing HSV-2 infection could reduce rates of HIV transmission and HIV disease progression. The study, which began recruitment at the 14 African sites in November 2004, ended follow-up of participants in October 2008. The study was randomized, placebo-controlled and double-blinded, meaning that both participants and care providers did not know which treatment the participants were receiving. Both the placebo and treatment groups received standard HIV prevention services, which included being supplied with condoms, treated for other sexually transmitted infections, and provided care for HIV infection. All participants received extensive counseling, both individually and as a couple, throughout the study period, on how to reduce the risk of HIV infection.

Scientists in the USA have discovered why smokers may be more prone to chronic gum disease (periodontitis). One of the bacteria responsible for this infection responds to cigarette smoke - changing its properties and the way it infects a smokers mouth.

The study published recently in the Society for Applied Microbiology journal Environmental Microbiology, showed that the bacterium Porphyromonas gingivalis adapts and changes its DNA and membrane proteins in response to cigarette smoke.

Several genes of P. gingivalis associated with its virulence (infectivity), detoxification, oxidative stress mechanisms and DNA repair are altered by exposure to cigarette smoke. As a result, the expression of a number of the proteins in the cell membrane is changed. This affects important characteristics of the bacterial cells themselves and how the immune system recognizes this pathogen.

This could explain why smokers are more likely to be resistant to treatment for periodontitis and are more susceptible to oral disease caused by infection with P. gingivalis.

Finding an effective treatment for smokers infected with P. gingivalis will be easier now that these changes in the bacterium's 'properties' have been identified.

University of Louisville researcher, Dr David Scott said: "It has long been known that smokers are more susceptible to periodontitis than are non-smokers. However, the reasons why are not so clear. Our study shows, for the first time, that components in cigarette smoke alter key characteristics of a major bacterial pathogen which, subsequently, changes how our immune system reacts to it. It may turn out that we need to develop alternate treatment plans for smokers and non-smokers".

The US Centers for Disease Control and Prevention (CDC) said that doctors should not delay giving antivirals to pregnant women with flu symptoms because the risks of premature labor, pneumonia and dehydration are too great and outweigh the risk of the drug affecting the baby.

Dr. Anne Schuchat, Interim Deputy Director for Science and Public Health at the CDC said in a press briefing about the H1N1 situation on Tuesday:

"We are ... seeing some severe complications among pregnant women in this year's novel H1N1 virus problem."

The CDC is currently investigating about 20 cases of pregnant women infected with the virus, some of them with severe complications.

One of the three H1N1 deaths in the US was a pregnant woman in Texas who did not take anti-flu drugs.

Flu usually affects pregnant women more severely than other people because their immune system is weaker. Shuchat said pregnant woment are more vulnearable to severe complications include pneumonia and dehydration as well as complications for the newborn, like premature labor".

She said the CDC urge doctors caring for pregnant women who they think may have flu to treat them promptly with antivirals.

"Sometimes, physicians are reluctant to treat pregnant women with medicines, and sometimes pregnant women are reluctant to take medicines because, of course, they are sometimes risky during pregnancy," said Shuchat.

But she said that experts who have looked at the situation in detail are adamant that the benefits to pregnant women with flu of taking antivirals are much greater than the "theoretical concerns about the drugs".

Without actually naming them, Shuchat said that either of the two medicines that the novel H1N1 is susceptible to should be used, but she was probably referring to Tamiflu and Relenza.

Relenza (zanamivir) and Tamiflu (oseltamivir) belong to the same class of drug known as neuraminidase inhibitors used to treat Influenzavirus A and Influenzavirus B.

In a separate briefing reported by the New York Times, CDC medical officer Dr Denise Jamieson, also advised doctors not to delay. If there is flu in the community, and you would otherwise not hesitate to give antivirals to a non-pregnant patient with flu symptoms, then:

"Don't delay because she's pregnant ... the benefit of giving Tamiflu outweighs the risk," said Jamieson.

She added that "Tamiflu and Relenza are fairly safe in pregnancy".

Shuchat said that while they didn't know a lot about this new H1N1 and pregnancy, it was important to look back on what is known about seasonal influenza and pregnancy, and the recommendation is that pregnant women are strongly urged to take the seasonal flu vaccine to protect themselves from complications during pregnancy.

She said the authorities are keen to stress the importance of prompt antiviral treatment in pregnancy and the CDC will be shortly be issuing a Morbidity and Mortality Weekly Report (MMWR) with some clinical data about the H1N1 pregnancy cases they have been investigating.

Schuhat also said that the way the US was using antivirals in response to the new H1N1 outbreaks was different to European countries. She said the circumstances in the US were very different to that of many countries in Europe.

In the US the virus is pretty much in every state, and she suspects it is also in the states that haven't reported confirmed cases yet.

"We don't have a situation where we can contain the virus's geographic distribution, and our focus is on reducing illness and death and mitigating the impact that this virus has as well as focusing our efforts on areas where they can have the most impact," said Schuhat.

So the priority is to use antivirals where the treatment will make a difference, she explained.

"And that's for people with severe illness presentation or for people who have underlying medical conditions or pregnancy, where the complications of an influenza infection might be worse than in other people," said Schuhat.

While other countries are still using the drug for preventive reasons, in the US the focus is on treatment. Prevention is not " likely to have a benefit here in the United States based on the transmission patterns we're seeing and the stage of the outbreak that was present by the time we recognized this virus", said Schuhat.