A study by researchers from the University of California, San Diego School of Medicine, in collaboration with Mexican researchers and health officials, shows that as many as 67 percent of injection drug users in Tijuana test positive for tuberculosis (TB) infection. The analysis, which underscores the urgent need for TB screening and treatment for populations that are also at risk for HIV infection, will be published in the May issue of the International Journal of Tuberculosis and Lung Disease (IJTLD).

"While injection drug users are known to be at risk for TB, this is one of the highest infection rates ever reported among this group," said principal investigator Richard Garfein, PhD, MPH, associate professor in the Division of Global Public Health and Department of Medicine at UC San Diego. The analysis is part of a bi-national, community-based study called Proyecto El Cuete that includes more than 1,000 illicit drug injectors residing in Mexico's largest U.S. border city.

What most concerns Garfein is that injection drug users are not only likely to have weakened immune system due to illicit drug use, but are also at high risk for HIV infection. This makes the situation much worse for individuals infected with TB, because HIV further weakens a patient's immune system.

Worldwide, tuberculosis is a leading cause of death among persons with AIDS. Once a person becomes infected from breathing in TB bacteria, the immune system generally encapsulates the bacteria and prevents it from growing. When this happens, the bacteria remain alive in an inactive state called latent TB infection. But the TB bacteria can become active at a later date if the person's immune system is weakened, for example, in those with AIDS.

"Persons with latent TB infection are not sick and are not contagious," said co-investigator Dr. Rafael Laniado-Laborin, MD, chief of Tijuana General Hospital's tuberculosis clinic, adding that, in otherwise healthy individuals, the chance of the latent TB becoming active is about 10 percent over their lifetime. "However, if individuals become infected with HIV, their chance of developing active TB increases to 10 percent per year."

Once active, TB bacteria replicate in the lungs. Symptoms include coughing, which facilitates the airborne spread of bacteria to others.

"Given that two-thirds of Tijuana's injection drug users have latent TB infection, the majority of those who become HIV infected - a risk that is increasing - are also likely to develop active, contagious TB," said Garfein.

TB is endemic in Mexico, where children are routinely vaccinated with the Bacillus Calmett-Guerin (BCG) vaccine, which is not highly effective but can prevent some serious forms of childhood TB. Unfortunately, the vaccine can cause false-positive results with the tuberculin skin test (TST), used for over a century to detect TB infection. For this reason, estimates of TB prevalence using the TST are unreliable in areas of Mexico where the BCG vaccine is given, making it difficult to anticipate future health care needs for at-risk populations.

Instead of TST, participants in this study were given a TB test called interferon-gamma release assay (IGRA) which measures the substance released by sensitized immune cells when they are exposed to TB bacteria. Neither test can differentiate between latent and active TB. However, the IGRA is more sensitive and specific in testing for TB because it doesn't cross-react with the BCG vaccine.

Injection drug users, age 18 years or older, were asked about past TB diagnosis, illness and treatment as well as the presence of TB symptoms such as persistent cough, fever or chills, shortness of breath, fatigue and unexplained weight loss. Participants with TB symptoms were referred to a municipal health clinic for further evaluation.

Of the 1,025 participants who received IGRA results, 681 (67%) tested positive for TB, with 13 individuals reporting symptoms. Injection drug users recruited from two neighborhoods nearest the U.S./Mexico border had 64% higher odds of being IGRA-positive than non-drug users. These odds increased by 20% for every five years of reported injection drug use.

Additional years of residence in Tijuana were also associated with greater prevalence of IGRA-positive results. One explanation is that more time spent among other injection drugs users in Tijuana increased the likelihood of exposure to TB. Only 4% of study participants tested positive for HIV infection. However, if HIV is not controlled and its prevalence increases, the number of injection drug users whose latent TB infection becomes active is destined to increase, according to the researchers.

"This at-risk population urgently needs better screening and treatment for TB,"said Laniado-Laborin. "Treatment reduces the TB reactivation risk by nearly 75%, while cutting the death rate of patients with HIV and TB in half."

Contrary to common stereotypes, individuals with major mental disorders are more likely to become victims of violent crimes when they are experiencing an increase in symptoms than they are to commit crime, according to a new study by Brent Teasdale, an assistant professor of criminal justice at Georgia State University.

Teasdale found that patients experiencing delusions, hallucinations and worsening symptoms generally are most likely to become victims of violence. In addition, individuals with mental disorders are particularly vulnerable for victimization during times of homelessness and when suffering from alcohol abuse.

"They actually have higher rates of victimization than they have of violence commission, which I think is counter to the stereotype that highly symptomatic, obviously delusional, visibly mentally disordered people are dangerous, unpredictable and violent," Teasdale said. "There's no one size fits all approach to these delusions, but the odds of victimization are multiplied almost by a factor of two when a person experiences these delusions."

Teasdale analyzed data from the MacArthur Violence Risk Assessment Study, a longitudinal study of psychiatric patients released from three psychiatric hospitals in Pittsburgh, Pa., Kansas City, Mo., and Worchester, Mass. During the MacArthur study, participants were interviewed every 10 weeks for one year about violence committed against them, stress, symptoms and social relationships.

When individuals with mental disorders experience increases in delusions, symptom severity and alcohol problems they may be more focused on their internal states and have fewer cognitive resources available to devote to interactions with other people, Teasdale said. Other research suggests that victimization happens because caretakers may be driven away, leaving the disordered unprotected.

"If the stigma is that those are people we need to protect ourselves from, one of the ways in which we might do that is self defensive violence. We might strike first and that would lead to the victimization of these folks," Teasdale said. "If there's a person that could intercede before that happens, that may be one strategy for reducing victimization risk."

The findings of the study are important for clinicians who must pay attention to warning signs of worsening disorders as potential risk markers for violent behavior committed by their client, Teasdale said. They could also aid in the creation of assessment tools that focus on victimization risk and classes that better educate families about caring for the mentally ill.

Researchers have identified tiny molecules that may lead to big breakthroughs in the treatment of hearing loss and deafness.

An international team, including researchers from Tel Aviv University in Israel and Purdue University, found that lack of these molecules causes abnormal development of the inner ear and leads to progressive hearing loss.

Donna Fekete, the Purdue professor of biological sciences involved in the study, said this new information could provide promising leads to treat hearing loss.

"The molecules we identified could be used as a molecular tool delivered directly into the ears of deaf people to induce regeneration of important sensory cells that would improve hearing," she said. "The molecules also could potentially help people with balance disorders related to inner ear function such as Meniere's disease."

The National Institutes of Health National Institute on Deafness and Other Communication Disorders, or NIDCD, reports that 36 million American adults have some degree of hearing loss.

In many cases of non-congenital hearing loss, the cause is degeneration of specialized sensory cells in the inner ear, called hair cells. Hair cells convert sound waves into electrical impulses that can be interpreted by the brain. According to the NIDCD, excessive noise, certain medications, aging and disease can damage or destroy hair cells. Because humans are unable to replace lost hair cells, hearing declines as they are lost.

The international research team identified microRNAs - tiny pieces of the genetic building block ribonucleic acid, or RNA - critical to the survival of hair cells. MicroRNAs regulate genes by selectively preventing certain genes from making proteins.

Karen Avraham, the Tel Aviv University professor who led the study, said this research shows that a loss of certain microRNAs can cause deafness.

"We found that hair cell microRNAs are regulators involved in the normal development and survival of cells in the inner ear and are necessary for proper hearing," said Avraham, who is a professor in the Department of Human Molecular Genetics. "Until very recently, science only knew that mutation in protein-coding genes caused deafness. We went a layer deeper and discovered that the loss of microRNAs leads to deafness as well."

In recent separate studies conducted in Spain and the United Kingdom, mutations in a single microRNA were reported to cause deafness in humans and mice, showing the importance of microRNAs in the inner ear and the link to human hearing loss, Avraham said.

Earlier research had shown microRNAs to be involved in ear development, but this study is the first to remove the microRNAs at the time when hair cells are just beginning to form, Fekete said. A paper detailing the work was published in the April 14 issue of the Proceedings of the National Academy of Sciences.

In addition to Avraham and Fekete, co-authors of the paper include assistant research scientist Takunori Satoh and research assistant Deborah J. Biesemeier from Purdue; Lilach Friedman, Amiel Dror, Eyal Mor, Tamar Tenne, Ginat Toren and Noam Shomron from Tel Aviv University; and Eran Hornstein from The Weizmann Institute of Science in Rehovot, Israel.

The first microRNA was discovered in 1993, and the field has taken off within the last eight years, Fekete said.

"In a sense it is a whole new way of looking at gene regulation that we didn't know much about 10 years ago," she said. "Now people all over the world from different fields are trying to figure out the roles microRNAs play and how they can be used to improve human health."

Fekete and the Purdue team examined several microRNAs in zebrafish to determine what role each played.

"There are hundreds of microRNAs, and the question is which ones are doing what in terms of keeping hair cells alive and developing properly," Fekete said. "In this paper, we identified two microRNAs that, when removed, reduced the number of hair cells developed."

The missing microRNAs also each caused abnormal development of larger organs of the ear. One prevented development of the semicircular canals involved in balance, and the other prevented development of an organ called an ear-stone that is needed to sense movement, Fekete said.

Additional unpublished work by Satoh and Purdue graduate student Haiqiong Li in Fekete's lab expands the list of microRNAs that regulate hair cell numbers to seven, Fekete said.

Her team next plans to investigate other microRNAs thought to be involved in hair cell development and to look into whether overexpression of these molecules could lead to regeneration of these sensory cells from so-called supporting cells. In earlier research, Fekete showed that hair cells and supporting cells have the same biological origin.

"Research has shown that in other animals supporting cells can give rise to hair cells, so the real challenge is to determine why this doesn't happen in mammals," Fekete said. "One thought is that microRNAs might be able to turn off supporting cell genes and make them more susceptible to becoming hair cells, effectively getting them to switch fates."

A relatively low dietary intake of vitamins A and C boosts the risk of asthma, suggests a systematic analysis of the available evidence, published ahead of print in the journal Thorax.

These findings clash with a large review of the evidence, which was published last year.

Observational studies in recent years have pointed to a link between dietary antioxidant vitamins (A,C, and E) and asthma, but the results of clinical trials have proved inconclusive, claim the authors.

In a bid to try and clear up the confusion, they conducted a comprehensive search of major databases of peer reviewed research, abstracts of conference proceedings on asthma and wheeze, and bibliographies from 1980 to the end of 2007.

They found 40 relevant studies, which had looked at the association between vitamin intake and asthma and wheezing, out of more than 2,600.

The pooled results showed that dietary intake of vitamin A was significantly lower among those with asthma than in those who had not been diagnosed with the disease.

The average intake of 182 ug a day was equivalent to between a quarter and a third of the recommended daily amount of vitamin A.

Vitamin A intake was also significantly lower - equivalent to around half of the recommended daily amount - in those with severe disease than in those with mild asthma.

Low circulating levels of vitamin C in the bloodstream and lower dietary intake of foods containing vitamin C were also associated with a 12% heightened risk of asthma.

Vitamin E intake was not associated with a diagnosis of asthma, but blood levels were significantly lower among those with severe disease compared with those whose symptoms were mild.

This translates into an intake that is 2 mg/day or 20% lower than the recommended daily amount of vitamin E.

The findings for a link between dietary antioxidants and wheeze were less consistent.

Ah, spring is in the air and so are billions of grains of pollen released from grasses, trees and flowering plants. They're the culprit behind seasonal allergies, the "hay fever" many people experience with its stuffy and runny nose, sneezing, coughing and itching.

But allergies don't have to keep you from firing up the lawn mower, trimming trees, working in the garden or building that new patio. Ewen Tseng, M.D., otolaryngologist on the medical staff at Baylor Medical Center at Frisco, offers these tips to avoid allergens when you're doing your spring landscaping:

- If you've been prescribed an oral antihistamine by your doctor, be sure to take it before heading outdoors.

- Wear protective clothing, including gloves, to reduce exposure to allergens and avoid transferring pollen from your hands to your eyes and nose.

- Wear a mask. "Think of the nose as a filter," says Dr. Tseng. "For seasonal allergies, the nose is the first line of defense."

- Wash your hands, change clothes and shower after you're finished.

"An alternative to wearing a mask is nasal irrigation with saline [saltwater] to rinse allergens from the nose it's like cleaning your own air filter," adds Dr. Tseng. Irrigation kits are available at pharmacies and grocery stores.

You could attempt to "allergy-proof" your yard and garden by selecting plants that pollinate through insects rather than by releasing pollen. Unfortunately, you can't avoid the wind-blown pollens from other trees and plants, which often travel long